UPTEC-F11061

Examensarbete 30 hpDecember 2011

Environmental analysis of zirconium alloy production

Mikael Lundberg

Teknisk- naturvetenskaplig fakultet UTH-enheten Besöksadress: Ångströmlaboratoriet Lägerhyddsvägen 1 Hus 4, Plan 0 Postadress: Box 536 751 21 Uppsala Telefon: 018 – 471 30 03 Telefax: 018 – 471 30 00 Hemsida: http://www.teknat.uu.se/student

Abstract

Environmental analysis of zirconium alloy production

Mikael Lundberg

The generation of electricity in light water nuclear power plants uses zirconium alloys as the primary containment and cladding of the nuclear fuel. The environmental impacts of the production of zirconium alloys have been analyzed form a lifecycle perspective. From the mining of the zirconium-bearing mineral zircon to the finished zirconium alloy tube. A qualitative study indentifying the production processes and their potential environmental impacts have been performed. A quantitative study to perform a lifecycle analysis of the zircon mining and mineral separation was carried out. The life cycle analysis for the zircon mining was compared to the current lifecycle analysis (LCA) in Vattenfall's Forsmark nuclear power plant environmental product declaration (EPD). The results showed that the additional impact on Forsmark's EPD, when including the mining of zircon, is below 0.1% of the current levels for all parameters analyzed. A lifecycle analysis for the production of zirconium metal and zirconium alloy tube could not be performed due to lack of data from the zirconium metal industry. The major direct emissions from the zircon mining industry are related to the use of fossile fuels in machinery. The major direct emissions from the zirconium metal manufactoring industry are related to the use of acids.

Sponsor: Vattenfall ABISSN: 1401-5757, UPTEC-F11061Examinator: Thomas NybergÄmnesgranskare: Mattias LantzHandledare: Lasse Kyläkorpi

0.1 Popularvetenskaplig sammanfattning

Zirkoniumlegeringen zircalloy anvands som konstruktionsmaterial vid tillverkn-ing av karnbranslet i dagens karnkraftverk av lattvattentyp. Legeringen zircal-loy som anvands for att innesluta uranet som ar sjalva kallan till energiutvinnin-gen i ett karnkraftverk. Vid tillverkningen av karnbransle placeras uran i formav sma kutsar i langa ror av zircalloy, dessa ror monteras sedan ihop paket om etthundratal ror for att bygga upp ett bransleelement. Det ar dessa bransleelementsom laddas in i karnkraftveken varje ar vid revisionsavstallningen. Bransle-inkapslingen av zicalloy har tva huvudsakliga funktioner, dels att halla urankut-sarna pa plats, dels att fungera som en barriar for att forhindra spridningav radioaktiva amnen. Anledningen till att zirkoniumlegeringar anvands sombransleinkapsling ar att zirkonium ar motstandskraftigt mot korrosion samt attdet latt slapper igenom de neutroner som bildas vid karnklyvningar och somkravs for att uppratthalla klyvningen av uranatomerna.

Denna rapport syftar till att undersoka miljoaspekterna av tillverkningen avzirkoniumlegeringar, fran gruvbrytning av den zirkoniuminnehallande mineralenzirkon till tillverkningen av de zircalloy-ror som anvands for karnbransletillverkning.Rapporten behandlar inte sjalva tillverkningen av karnbransle dar urankutsarmonteras i zircalloy-ror for att bilda bransleelement. Fokus i rapporten liggerpa att kvalitativt beskriva hur gruvbrytningen och tillverkningsprocessen gartill samt att kvantitativt beskriva hur stora de utslapp som forekommer ar.

Zirkonium utvinns ur mineralen zirkon som ar en zirkonium-kisel-oxid som arvanligt forekommande i naturen. Mineralen forekommer i laga koncentrationeni vulkanisk berggrund. Nar berggrunden eroderar frigors mineraler som sand-korn som sprids med vatten och vind. Pa grund av att zirkon ar tyngre anden vanlig kiseloxid sand sedimenteras och koncentreras zirkonsanden i sand-bankar pa strander och sanddyner tillsammans med andra tyngre metaller somtitan, uran, torium och sallsynta jordartsmetaller. Dagens gruvbrytning skerfran fyndigheter dar zirkonsanden koncentrerats under perioderna mellan desenaste istiderna. Den storsta delen av brytningen sker fran nuvarande ellerhistoriska havsstrander. De lander med de storsta fyndigheterna och storstaproduktionen ar Australien och Sydafrika som tillsammans star for ca 2/3 avbade fyndigheterna och produktionen.

Gruvbrytningen sker fran oftast fran sanddyner som aterfinns ett flertal me-ter under markytan, darmed behover de ovre jordlagren flyttas. Detta skervanligtvis med lastmaskiner, dumpers och bulldozers men om grundvatten-forutsattningarna ar de rattas anvands en mudderteknik dar sanden blandasmed vatten och sugs upp. Marken aterstalls kontinuerligt i takt med att bryt-ningen foljer malmkroppen framat. Sanden fors till ett anrikningsverk som kon-centrerar den tunga mineralsanden. Denna process bygger enbart pa fysikaliskseparering, inga kemikalier anvands. Zirkonet anrikas genom sedimentering,elektrostatiskt och magnetisk separation. Den stora miljopaverkan fran bryt-nings och anrikningsprocesserna kommer ifran de stora markytorna som skovlasfor att komma at malmen och fran de utslapp som sker fran forbranning av fos-sila branslen i de maskiner som anvands. Uran och toriumhalten i mineralernamedfor aven radiologiska krav pa arbetsmiljoatgarder.

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Det anrikade zirkonet skeppas sedan till producenterna av zirkonium metalldar sanden genomgar en serie kemiska processer for att separera zirkonium frankisel och sedan zirkonium fran hafnium. For att avlagsna kisel anvands enhogtemperaturprocess med tillsats att kol och klor. For separationen av zirko-nium fran hafnium anvands en av tva olika metoder beroende pa tillverkareden ena processen anvander en kalium-aluminium-klorid saltsmalte-separationden andra processen anvander losningsmedlet metylisobutylketon samt saltsyra,svavelsyra och ammoniumhydroxid. Metallen reduceras med magnesium foratt rena bort kloridrester och vakuumdestilleras tills en poros substans kallad”zirkoniumsvamp” aterstar. Den stora miljopaverkan har ar utslapp av badelosningsmedel och syror samt de rester av uran och torium som falls ut i pro-cessen.

Den rena porosa zirkoniumsvampen smalts ner till solida zirkonium stavar somsedan smids i en serie av processer for att producera de somlosa ror som anvandsvid tillverkningen av karnbransle. Forst kompakteras zirkoniumsvampen i enpress till nagot som kan liknas med gigantiska svetspinnar, som sedan smaltsner i en vakuumugn som fungerar som en gigantisk pinnsvets. Smaltan stel-nar till en cylinder som sedan smids ut till langre cylindrar som kapas uppmin kortare bitar. Ett hal borras genom centrum av de kortare cylindrarna,sedan klas de med ett smorjande material innan de pressas ut till langa somlosaror. Det smorjande materialet tas bort med vatefluorid och salpetersyra in-nan roren ratas upp och kapas till sin slutliga langd. Den storsta miljopaverkanfran denna process ar energiatgangen fran smaltnings och smidnings processernasamt anvandandet av vatefluorid och salpetersyra.

Ett mal med rapporten ar att genomfora en analys for att se hur stor paverkanzirkonium legerings tillverkningen har pa utslappen fran 1kWh el produceradvid ett svenskt karnkraftverk. Malet var att genomfora en livscykelanalys avtillverkningen av zircalloy-ror, detta kunde tyvarr inte genomforas pa grund avbrist pa data fran tillverkarna av zirkoniumsvamp och zircalloy-ror. Endast enanalys av gruvbrytningen och dess paverkan pa en livscykelanalys av elen pro-ducerad i Forsmarks karnkraftverk kunde genomforas.

De undersokta parametrarna ar utslapp av: vaxthusgaser, forsurande amnen,ozonskapande amnen, overgodande amnen och partiklar samt resursanvandandetav ravatten och energi. Resultatet av denna livscykelanalys var att om utslappenfran tillverkningen av de zirkonium legeringar laggs till Forsmarks nuvarandelivscykelanalys sa kommer utslappen inte att oka med mer an 0,1% for nagonav de analyserade parametrarna.

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Contents

0.1 Popularvetenskaplig sammanfattning . . . . . . . . . . . . . . . . 3

1 Introduction 111.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111.2 Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111.3 Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121.4 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

1.4.1 Availability of data . . . . . . . . . . . . . . . . . . . . . . 121.5 Structure of the report . . . . . . . . . . . . . . . . . . . . . . . . 13

2 The Manufacturing of zirconium alloys 142.1 Introduction to zirconium . . . . . . . . . . . . . . . . . . . . . . 142.2 Zircon mining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

2.2.1 Preparing for mining . . . . . . . . . . . . . . . . . . . . . 202.2.2 Mining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212.2.3 Heavy minerals concentration . . . . . . . . . . . . . . . . 232.2.4 Radiological concerns . . . . . . . . . . . . . . . . . . . . 252.2.5 Mine rehabilitation . . . . . . . . . . . . . . . . . . . . . . 262.2.6 Environmental impacts . . . . . . . . . . . . . . . . . . . 28

2.3 Mineral separation . . . . . . . . . . . . . . . . . . . . . . . . . . 282.3.1 Radiological concerns . . . . . . . . . . . . . . . . . . . . 312.3.2 Environmental impacts . . . . . . . . . . . . . . . . . . . 32

2.4 Zirconium sponge production . . . . . . . . . . . . . . . . . . . . 322.4.1 Zirconium-hafnium separation process . . . . . . . . . . . 342.4.2 Zirconium sponge production process . . . . . . . . . . . . 352.4.3 Environmental impacts . . . . . . . . . . . . . . . . . . . 36

2.5 Zircaloy ingot production . . . . . . . . . . . . . . . . . . . . . . 372.5.1 Zirconium alloy ingot production processes . . . . . . . . 372.5.2 Environmental impacts . . . . . . . . . . . . . . . . . . . 40

2.6 Zircaloy tube production . . . . . . . . . . . . . . . . . . . . . . . 412.6.1 Zircaloy tube production processes . . . . . . . . . . . . . 412.6.2 Environmental impacts . . . . . . . . . . . . . . . . . . . 43

3 LCA of zirconium production 453.0.3 Data sources . . . . . . . . . . . . . . . . . . . . . . . . . 46

3.1 LCA of zircon production . . . . . . . . . . . . . . . . . . . . . . 473.1.1 Data sources . . . . . . . . . . . . . . . . . . . . . . . . . 473.1.2 Impact on the LCA for Forsmark NPP . . . . . . . . . . . 48

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4 Discussion 50

5 Conclusions 525.1 Further work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Appendices 57

A List of companies 58

B Production flowcharts 60

C LCA study 76

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List of Figures

2.1 Generalized zirconium alloy tube production process . . . . . . . 152.2 Zirconium consumption by end use in 2008 [17] . . . . . . . . . . 182.3 Overview of zirconium mining . . . . . . . . . . . . . . . . . . . . 202.4 Bulldozer feeding mineral sand into a hopper. The hopper is

slowly moving to the right, through the deposit. The feed waterand slurry pipelines are shown in the bottom left. [20] . . . . . . 22

2.5 Dredge barges and wet concentration plant in an artificial dredgepond. Dredge barge spraying water to erode shores of dredgepond [22] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2.6 Left: Bank of spiral separators [3], Right: Spiral separator whereheavy minerals concentrate towards the center of the spiral [3] . . 24

2.7 Heavy mineral mining on North Stradbroke Island [27] . . . . . . 252.8 Mining with integrated rehabilitation [30] . . . . . . . . . . . . . 272.9 Overview of mineral separation . . . . . . . . . . . . . . . . . . . 292.10 Magnetic separation concept . . . . . . . . . . . . . . . . . . . . 302.11 Electrostatic separation concept . . . . . . . . . . . . . . . . . . . 312.12 Overview of zirconium sponge production . . . . . . . . . . . . . 332.13 Left: Raw zirconium sponge [46]. Right: Crushed zirconium

sponge [47] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 362.14 Overview of zircaloy ingot production . . . . . . . . . . . . . . . 382.15 Concept of zirconium alloy mixing, compacting and production

of consumable electrode . . . . . . . . . . . . . . . . . . . . . . . 392.16 Vacuum arc remelting process . . . . . . . . . . . . . . . . . . . . 392.17 Production of zirconium alloy materials . . . . . . . . . . . . . . 402.18 Overview of zirconium tube production . . . . . . . . . . . . . . 412.19 Left: Preheating of zirconium ingot in a furnace, Right: Reducing

zirconium ingot diameter by forging . . . . . . . . . . . . . . . . 422.20 Extrusion process . . . . . . . . . . . . . . . . . . . . . . . . . . . 432.21 Cold pilgering, pickling, annealing and straightening process . . . 43

3.1 Concept of environmental impact categories . . . . . . . . . . . . 46

B.1 Zircon mining flow chart . . . . . . . . . . . . . . . . . . . . . . . 61B.2 Wet concentration plant flow chart (1/2) . . . . . . . . . . . . . . 62B.3 Wet concentration plant flow chart (2/2) . . . . . . . . . . . . . . 63B.4 Mineral separation plant flow chart (1/2) . . . . . . . . . . . . . 64B.5 Mineral separation plant flow chart (2/2) . . . . . . . . . . . . . 65B.6 Zirconium-Hafnium separation flow chart (1/4) . . . . . . . . . . 66B.7 Zirconium-Hafnium separation flow chart (2/4) . . . . . . . . . . 67

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B.8 Zirconium-Hafnium separation flow chart (3/4) . . . . . . . . . . 68B.9 Zirconium-Hafnium separation flow chart (4/4) . . . . . . . . . . 69B.10 Zirconium sponge production flow chart (1/1) . . . . . . . . . . . 70B.11 Zirconium ingot production flow chart (1/1) . . . . . . . . . . . . 71B.12 Zirconium tube production flow chart (1/4) . . . . . . . . . . . . 72B.13 Zirconium tube production flow chart (2/4) . . . . . . . . . . . . 73B.14 Zirconium tube production flow chart (3/4) . . . . . . . . . . . . 74B.15 Zirconium tube production flow chart (4/4) . . . . . . . . . . . . 75

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List of Tables

2.1 World production and reserves of zirconium minerals 2009 in kilo-tonnes, (two different sources.) . . . . . . . . . . . . . . . . . . . 17

2.2 World leading zircon producers 2008 . . . . . . . . . . . . . . . . 192.3 Top five largest emissions by weight, reported by Australian zir-

con mining companies [33] . . . . . . . . . . . . . . . . . . . . . . 282.4 Properties of minerals commonly found in heavy mineral deposits 302.5 Example of substances reported from two Australian mineral sep-

aration plants [33] . . . . . . . . . . . . . . . . . . . . . . . . . . 322.6 Example of emissions reported from two American and one French

zirconium sponge producer [48] [49] . . . . . . . . . . . . . . . . . 372.7 Chemical composition of the two most common zirconium alloys 382.8 Example of emissions reported from two American and one French

zirconium alloy tube producer [48] [49] . . . . . . . . . . . . . . . 44

3.1 Zircon mining companies analyzed in the LCA study . . . . . . . 473.2 Emissions and resource consumption for the production of 1 kg

zircon in Australia, based on 2009 year production . . . . . . . . 483.3 Emissions and resource consumption for the production of 1 kWh

electricity form Forsmark NPP excluded zircon production com-pared to emissions and resource consumption contribution fromthe zircon production . . . . . . . . . . . . . . . . . . . . . . . . 49

A.1 List of zirconium mining companies . . . . . . . . . . . . . . . . . 58A.2 List of zirconium sponge manufacturers . . . . . . . . . . . . . . 59A.3 List of zirconium alloy manufacturers . . . . . . . . . . . . . . . . 59

C.1 Australian Zircon Emissions 2009 [33] . . . . . . . . . . . . . . . 76C.2 Australian Zircon Production 2009 [56] . . . . . . . . . . . . . . . 76C.3 Australian Zircon Facilities 2009 [33] . . . . . . . . . . . . . . . . 76C.4 Bemax Resources Limited Emissions 2009 [33] . . . . . . . . . . . 77C.6 Bemax Resources Limited Facilities 2009 [33] . . . . . . . . . . . 77C.7 Exxaro Production 2009 [57] . . . . . . . . . . . . . . . . . . . . 77C.8 Exxaro Emissions and Resource Consumption 2009 [57] . . . . . 77C.9 Iluka Resources Limited Emissions 2009 [33] . . . . . . . . . 78C.10 Iluka Resources Limited Production 2009 [58] . . . . . . . . . . . 78C.11 Iluka Resources Limited Facilities 2009 [33] . . . . . . . . . . . . 78C.12 Iluka Resources Limited Emissions and Resource Consumption

2009 [58] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79C.13 Tiwest Emissions 2009 [33] . . . . . . . . . . . . . . . . . . . . . 79

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C.14 Tiwest Production 2009 [57] . . . . . . . . . . . . . . . . . . . . . 79C.15 Tiwest Facilities 2009 [33] . . . . . . . . . . . . . . . . . . . . . . 79C.16 Kenmare Resources Production 2009 [59] . . . . . . . . . . . . . 80C.17 Kenmare Resources Emissions and Resource Consumption 2009

[59] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80C.18 USGS Mineral Prices 2009 [55] . . . . . . . . . . . . . . . . . . . 80

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Chapter 1

Introduction

1.1 Background

In recent years, the public and the electricity custumers have started to showa growing interest in how the electricity is generated and how it affects theenvironment. As a response to this 99% of Vattenfall’s Swedish generationcapacity produce Environmental Product Declarations (EPD) [1]. An EPD is adeclaration of the environmental impact a product causes during its completelife-cycle and is based on the ISO 14025 standard for environmental lables anddeclarations. The EPD system provides the costumers and general public witha lifecycle based assessment of environmental impacts of the related product. Inthis case, the product is 1 kWh of electricity. The EPD is based on quantitativedata on significant environmental aspects verified by a third party. The certifiedEPDs do not include any form of subjective judgement or valuation of theenvironmental performance. In addition to the EPDs, the electricity producedat the Swedish nuclear power plants in Forsmark and Ringhals are since 1999certified according to the ISO 14001 standard for environmental managementsystems. In the continuous work of Vattenfall to improve the quality of theEPDs for the electricity from nuclear power plants, the production of zirconiumalloy products are one of the few remaining potential significant environmentalimpacts to be analyzed in detail.

1.2 Objectives

This report aims to qualitatively describe the processes used in the productionof nuclear grade zirconium alloy tubes and identify the potential environmentalimpacts of these processes. The objective is:

• to perfrom a lifecycle analysis to quantitatively determine the resourceconsumption and emissions associated with the production of 1 kilogramof nuclear grade zirconium alloy.

• To identify if the zirconium alloy production has a significant impact onthe environmental performance of the production of 1 kWh of electricityfrom Vattenfalls nuclear power plants.

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1.3 Limitations

This report includes a qualitative analysis of the processes used from the min-ing of zircon to the production of nuclear grade zirconium alloy tube. Theproduction of other zirconium alloy material such as spacer grids, channels etc.were not included. The assembly of zirconium; tubes, sheet and spacer grids toform nuclear fuel elements and the loading of uranium fuel into these are notincluded. The construction and decommissioning of the infrastructure requiredfor the zirconium metal production processes have not been included due to lackof data, i.e. only the operational impacts are analyzed.

1.4 Method

The qualitative study was predominantly performed as literature a study witha visit to Sandvik’s zirconium tube production at Sandviken in Sweden. Theliterature study has focused on online sources, such as company and governmentenvironmental control agency web pages, academic research articles and patents.The quantitative study aimed to perform a life-cycle analysis of zirconium alloyproduction, to be able to calculate the emissions and resource consumptionrequired to produce 1 kg of nuclear grade zirconium alloy tube. A survey withquestions was sent to the companies involved, (see Appendix A). Unfortunatelythe number of companies willing to participate in this study was too low toavoid company proprietary data to be singled out in the low sample of responses,therefore the survey was abbandoned.

Instead, only publicly available sources were used, such as company environ-mental and annual reports and governmental agency databases. However thelack of direct responses from the industry made it the zirconium sponge andalloy producers were scarce.

1.4.1 Availability of data

To perform a lifecycle study, data on resource consumption, emissions and pro-duction have to be obtained. This is not the kind of data companies willinglyshare, due to its proprietary nature. Emissions of substances with environmentalimpacts are something governments control by law and is therefore monitoredby control agencies. How these governmental agencies manage and publish thisdata varies between countries.

The quantitative study was intended to be carried out as a survey sent outto all involved companies from the zircon mines to the zirconium alloy tubeproducers. However this was not possible due to the low response rate fromthe industry. Instead only official available information could be obtained. Thismeant that only data from transparent companies and environmental controlagencies were available. Hence, only companies with an already strong environ-mental focus or operating in countries with transparent government agenciescould be included in this study. The lack of direct response from the industrylead to a lack of data in how potential waste streams are treated, recycled/reusedor discarded.

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Of the major mining countries investigated, only Australia and USA werefound to have controlling government agencies that openly publish environmen-tal reports online, for individual mining facilities. Some of the zircon miningcompanies publish detailed material on their production processes and wastetreatment.

For the zirconium metal producing countries only western countries wereinvestigated in detail and Canada, France, Sweden and USA were found to pub-lish facility level environmental reports online. The zirconium metal producingcompanies are very secretive about their proprietary information and publishvery little material on the production processes. However, since the zirconiummetal producers do not publish production rates of production price levels, noallocation of emissions could be performed and no lifecycle analysis could becarried out.

1.5 Structure of the report

This report is divided into two main parts. Chapter 2 contains a qualitativestudy to analyze the production processes and determine the processes with thelargest potential environmental impacts. The production process is divided intosubchapters according to the majors subprocess which each end with a discus-sion on the environmental impacts. Chapter 3 contains a lifecycle analysis onthe production of nuclear grade zirconium alloy and a discussion on the results.The overall results of the report will be discussed in chapter 4. Finally, the con-clusions and suggestions for further work will be presented in chapter 5. TheAppendix includes an extensive flowchart representation of the manufacturingprocesses.

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Chapter 2

The Manufacturing ofzirconium alloys

This chapter will explain the basic production processes used for manufacturingnuclear grade zirconium alloy material and the environmental impacts associ-ated with these processes. The manufacturing of zirconium alloys can be roughlydivided into five stages according to separation of production between differentfacilities, (see Figure 2.1).

• Mining and concentration of heavy minerals

• Separation of the zirconium bearing-mineral zircon

• Separation of zirconium from hafnium and the production of zirconiumsponge

• Production of zirconium alloy ingots

• Production of zirconium alloy tubes

2.1 Introduction to zirconium

Zirconium (Zr) is a metal with atomic number 40, it is located in the groupIVb period in the periodical table in the same period as Titanium (Ti) andHafnium (Hf). Zirconium occurs in nature in over 150 different minerals [2] butnever in its metallic form. Zirconium is the 18th most abundant element in theEarths crust [3]. Pure zirconium metal oxidize at ambient temperature to form apotective oxide layer that gives it special corrosion resistance. Small fragmentsof zirconium metal (with high surface area to mass ratio) can spontaneouslyignite at room temperature. Solid zirconium metal can not self-ignite at roomtemperature but will rapidly oxidize at temperatures above 900◦C. Zirconiumhas a melting point of 1852◦C and a boiling point of 4377◦C, at atmosphericpressure.

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Figure 2.1: Generalized zirconium alloy tube production process

The primary source for economically recoverable zirconium is the zirconiumsilicate mineral zircon (ZrSiO4). Minor amounts of zirconium is also recoveredfrom the mineral baddeleyite (ZrO2). Zircon occurs alongside titanium miner-als in so called heavy mineral sand deposits. Heavy mineral sands is the termused to describe minerals with a specific gravity greater than 2.9g/cm3, this canbe compared to the most common mineral in sand, quartz (SiO2) with a spe-cific gravity of 2.7g/cm3. [4] The most notable titanium minerals usually foundtoghether with zircon is rutile (TiO2), ilmenite (Fe2O3 · 3 TiO2) and leucox-ene (Fe2O3 ·TiO2 ·mH2O) which are all commercially mined for their titaniumcontent. Historically zircon was recovered as a byproduct from the titaniumminerals but in recent years the higher demand and price for zircon have shiftedthe balance and new mining projects have zircon as their primary economicalmineral.

Zircon occurance

Heavy mineral sands are found in alluvial or aeolian placer deposits which aresedimentary deposits where the accumulation of mineral have occurred due togravitational concentration over time. Alluvial deposits are formed througherosion and concentration by water and aeolian deposits are from erosion andconcentration by wind. The concentration occurs due to the relative differencein specific gravity of heavy mineral sand and quartz.

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Alluvial deposits are formed through erosion by water when waves wash inover ocean beaches and carry away the lighter materials leaving the heavierbehind, or by running water in rivers where the denser materials are sedimentedbefore the lighter. This lead to a concentration of heavy mineral on beaches or inriverbanks. Most of the historic accumulated deposits are from the Quaternaryperiod i.e. the last 2.6 million years. [5] In this period, minerals deposits wereaccumulated during the cycle of glacial and interglacial periods when the sealevels rose and fell hundreds of meters. When the sea level rose old depositswere eroded, reshaped and concentrated. When the sea level fell, deposits wereleft behind as beaches. [5]

In the case of the historically accumulated deposits, these may now be locatedseveral hundred kilometers inland due to the marine regression since the lastintergalacial period. The deposits may since then have been covered by laterdeposited material and may now be located a few to tens of meters under ground.A beach deposit may have a mineralization of up to 90% heavy minerals, buttypical grades are 5-20% heavy minerals. [5] The Murray and Eucla Basinsin Australia are examples of historic shoreline deposits, the Indian beaches inOrissa, Kerala and Tamil Nadu are examples of contemporary beach deposits.[6]

Aeolian deposits are formed by erosion by wind where the wind carry sandfrom beaches inland to form dunes. As the dunes migrate the lighter mate-rials are carried away further and the heavier minerals are left behind andare concentrated into heavy mineral deposits. Dunal deposits tend to have alower mineralization than the beach deposits, typically 0.5-15% heavy minerals.What the dunal deposits lack in concentration they make up for in size. Atypical dunal deposit is larger than a beach deposit, both in physical size andtotal mineralization. The South African Kwa-Zulu Natal and Australian NorthStradbroke Island dunes are examples of historic, now vegetated, sand duneswhile the Senegalese Grande Cote dunes are examples of contemporary movingsand dunes.

High heavy mineral concentration does not necessarily mean a high zircongrade. The zircon share of the total heavy minerals varies greatly betweendifferent deposits from 0-60% with a typical concentration of 10% [7]. Themineral zircon contains 0.4-4% [8] hafnium with a typical concentration of 2%[9], this is because zirconium and hafnium have very similar chemical propertieswhich allow hafnium to replace the zirconium in the mineral and form hafnon(HfSiO4). Hafnon always coexistswith zircon and the term zircon used in thereport will refer to zircon with hafnon impurities unless other stated. In fact, thesimilarites in chemical properties is a problem for the production of nuclear gradezirconium, as will be evident in the zirconium-hafnium separation described inSection 2.4.1.

Zirconium mining

The majority of the mining of zirconium minerals today originate from zirconin beach or dunal deposits. River deposits are most often too small to be eco-nomically viable. There are a few exceptions though, the Kovdorsky mine [10]

16

on the Kola peninsula in north western Russia is the only commercial badde-leyite mine, that extracts baddeleyite as a co-product from its apatite and ironore mining. Baddeleyite also coexist with zircon to form the mineral caldasite(ZrO2, ZrSiO4) wich is mined in the Minas Gerias region in Brazil [11]. For-merly baddeleyite was also mined in the Palabora [12] mine in South Africawhich ceased production in 2002. Another exception is the extraction of zirconfrom oil sands tailings in the Athabasca basin in Canada [13]. These alternativeproduction sources add together to less than 1% of the total world productionof zirconium minerals and will not be discussed further.

The world production and reserves of zircon is concentrated to a few majorproducing countries, (as seen in Table 2.1). If production were to remain at the2009 production levels the known resources would last over 40 years.

Table 2.1: World production and reserves of zirconium minerals 2009 in kilo-tonnes, (two different sources.)

Country Production [kt] [14] Reserves(a) [kt] [15]Australia 474 23000South Africa 392 14000China 140 500United States 100 3400Indonesia 63 NAIndia 36 3400Ukraine 35 4000Mozambique 29 NABrazil(b) 25 2200Sri Lanka 10 NAVietnam 8 NARussia(b) 7 NAMalaysia 1 NAOther NA 5000Total 1320 56000(a) Reported as ZrO2 equivalents(b) Including baddeleyite and caldasite

The mineral zircon is used for a range of different applications, (as seen inFigure 2.2). The major end-use of zircon is the ceramics industry where zir-con is used as on opacifier in tiles and sanitary ware. Zircon is also used asmoulding sand in foundry applications or as refractory material in bricks forhigh temperature furnaces. Other uses include the production of fused zirconia(syntetic Zr02) for refractory or ceramics applications, production CRT glassor production of zirconium chemicals which is the base of range of zirconiumderivatives.

Finally a small fraction of the world production of zircon is used in the produc-tion of zirconium metal used in chemical process industries and nuclear power

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plants. The nuclear grade zirconium metal market is a market with few ven-dors with a surplus capacity. The worldwide nuclear grade zirconium annualproduction capacity is about 8600 tonnes and the demand is about 5000 tonnes[16]. This indicates that the nuclear grade zirconium production only accountsfor 0.5% of the total world zirconium mineral production.

Figure 2.2: Zirconium consumption by end use in 2008 [17]

Zirconium alloy value chain

The value chain of zirconium strats with the mining of zircon by mining com-panies often specialized on just mining of heavy mineral sand, the companiesinvolved are shown in Table A.1. The zircon is sold to the zirconium spongeproducers, shown in Table A.2. All zirconium sponge producers also producezirconium alloy tubes, sheet metal and other zirconium alloy products. How-ever, not all companies producing tubes and sheet metal produce zirconiumsponge. The zirconium sponge producers sell some of the sponge to the otherzirconium alloy producing companies, as shown in Table A.3.

The finished zirconium alloy tube, sheet metal etc. are used in fuel fabrication,where the zirconium and uranium are assembled into nuclear fuel elements.Most of the zirconium alloy producers also have their own fuel fabrication. Thefinished nuclear fuel elements are sold to the nuclear power plant operatorswhich use the fuel in the reactor core for 4-5 years. When the fuel is burnt outthe fuel elements are placed in temporarily cooling ponds at the nuclear powerplant awainting disposal in a final repository. The zirconium tubes acts as oneof the saftey barriers in the final repository. In the once through fuel cycle nozirconium are recycled from irradiated nuclear fuel elements.

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Zirconium in the nuclear industry

Zirconium alloys are a key material in modern light water nuclear power plants.A boiling water reactor (BWR) contain about 44 tonnes of zirconium and apressure water reactor (PWR) contain about 29.5 tonnes of zirconium. [16]Zirconium alloys are used as construction material and fuel cladding i.e. thematerial which contain the uranium fuel pellets. The uranium pellets are placedin cladding tubes which are held together by spacers and assembled into fuelbundles and in surrounded by a fuel channel. Most of the materials in thesecomponents, except the fuel, are zirconium alloy materials.

Zirconium alloys are used as a construction material due to its high meltingtemperature, excellent corrosion resistance and low neutron cross section. Thelow thermal absorption cross section for neutrons (i.e. probability to absorblow energy neutrons), gives two major benefits in a reactor environment. Thefirst benefit is increasing the ratio of neutrons per fission that are availableto initiate a new fission. The second benefit is decreasing the neutron inducedswelling which occurs when neutrons dislocate atoms in metal lattice structures.The dislocations lead to swelling and embrittelment of the metal making it proneto cracking.

2.2 Zircon mining

This chapter will explain the zircon mining process and analyze potential envi-ronmental impacts. For the full process flowchart refer to Appendix B.1. Themining processes can rougly be divided into four stages, (as seen in Figure 2.3):

• Exploration and preparation for mining

• Mining of mineral sands

• Concentration of heavy minerals

• Rehabilitation of mined areas

Table 2.2: World leading zircon producers 2008Company Operating Mining Market

countries technique shareIluka Resources Ltd Australia, USA Dry 34%Exxaro South Africa Dry 15%Richards Bay Minerals South Africa Dredge 18%Bemax Resources Ltd Australia Dry 4%DuPont USA Dredge 3%Tiwest JV Australia Dry 2%Other N/A NA 24%

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Figure 2.3: Overview of zirconium mining

2.2.1 Preparing for mining

When a probable heavy mineral resource have been identified using variousgeographical and geological tools an exploration drilling program is carried outto indentify the resource. Small drilling rigs much like those used for water wellor geothermal heat drilling are used to drill core samples in a grid covering theexploration area. The drilling pattern is typically asymmetric with a 100x200 mgrid used. [18] When a resource is found, the grid size is subsequently decreasedto better investigate the form and grade of the mineralization. During thedrilling, core samples are taken from the surface down to the underlying clayor bedrock up to 250 m below surface for deep deposits. [18] The samples aresent to a laboratory to determine the precise heavy mineral grade and mineralcomposition. Once the drill samples and laboratory analysis is completed, athree dimensional structure of the mineralization is built which will be the basefor the planning of the mining operations.

When the mineral explorations have found a new deposit rich enough to facil-itate mining a feasibility, an environmental impact report and a rehabilitationplan need to be established. These reports will include details on how the miner-als will be mined and processed, what environmental impacts that are expected,how the rehabilitation will be carried out and the economics of the project. Tobe able to perform the rehabilitation of the mine, a field study establishingthe baseline conditions of the land is performed. This study is carried out inparallell with a mining feasibility study since it impacts the choice of miningtechnology and operations. The study aims to record the pre-mining conditionsof geographical topology, groundwater, land use, flora and fauna, etc. The landtopology is recorded and the groundwater levels and conditions are measured.The local species are recorded and seeds from vegetation may be collected to

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ensure the local vegetation is re-established post rehabilitation. [5] In order toget a mining licence to start a new mine, the mining and rehabilitation planand the environmental impact assesment have to sent to the respective author-ities. When all documments have been filed and the authorities granted allpermissions the mining can commence.

Zircon mining is carried out as strip mining. The mining operations typicallystart with the clearing of vegetation and clearing of topsoil to establish themining infrastructure such as roads and buildings. This is followed by theclearing of the deposit. If the deposit is covered by forest any lumber is firstharvested and firewood is collected. [5] The remaining vegetation is clearedusing bulldozers and the biomass is stored in stockpiles next to the mine pitawaiting rehabilitation. The bulldozers continue to clear the organic topsoil inthe same manner once again to be stored in stockpiles next to the mine pit. Ifthe deposit is located deep underground there will be a further need to removethe overburden which is performed using similar methods. All actions up tillthis point will have been similar for most mines but after the clearing of topsoiland overburden the difference between the two main mining techniques becomesevident.

2.2.2 Mining

There are two main types of mining techniques; dredge mining and dry mining.The two techniques differ by the way they extract the minerals sand, but aresimilar in the way they concentrate the sand to form heavy mineral concentrate.The choice of mining technique depend on the deposits geological structure.Dredge mining involves floating dredges and concentration plant in an artificialpond which uses high pressure hose to erode the sandbanks. The base of thesandbanks are washed away and the sand fall into the pond where the floatingdredge can scoop up the sand. Dredge mining requires a non permeable bottomof the deposit to enable the formation of water tables. It is required thatthe groundwater level lies above the bottom of the deposit to facilitate theformation of the artificial pond upon which the dredge and the concentrationplant floats. The dredge mining technique is more suitable for mining largercontinous deposits with low amounts of clay such as dunal deposits. If depositsare large enough, contain low amounts of clay and have the right groundwaterproperties dredge mining is often economically favourable over dry mining.

Dry mining is suitable for most other types of deposits. Dry mining methodsinvolve the extraction of sand by conventional earth moving machinery such asfront end loaders, self-elevating scrapers, excavators or bucket wheel excavators.The transportation of the mineral sand to the concentrator is performed eitherby pumping as a slurry or by conveyor belts. A combination of both dredgeand dry mining is the hydraulic mining which uses high pressure water hoses toerode the deposit but no dredges or artificial pond. In this report only dredgeand dry mining will be described though, since it includes the same methodsused in hydraulic mining. For a flowchart description of the mining processesrefer to Appendix B.1.

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Dry mining

Dry mining techniques consist of a wide range of mostly diesel powered machinessuch as bulldozers, scrapers, front end loaders, excavators or bucket wheel exca-vators, all depending of the properties and location of the deposit. Bucket wheelexcavators are more suitable for large continuous deposits since their large sizeand cost, while front end loaders are more suitable for smaller deposits. Inde-pendent on how the sand is extracted, it is fed to a hopper for screening andremoval of oversize materials. [19]

Figure 2.4: Bulldozer feeding mineral sand into a hopper. The hopper is slowlymoving to the right, through the deposit. The feed water and slurry pipelinesare shown in the bottom left. [20]

The sand is dug out by a excavator or a bucket wheel excavator, scraped ofthe surface of the deposit by a bulldozer or self-elevating scraper or scooped upby a front end loader. All techniques have the same aim, to keep a constantfeed of sand to the hopper. The bucket wheel excavator use a conveyor belt totransport the sand to the hopper. The front end loader might load directly intothe hopper or into a truck for transportation to the hopper. The scraper andbulldozer technique use a slightly different approach where the scraper moves thesand close to the hopper and the bulldozer feed it into the hopper. The hoppermoves through the deposit as it slowly crawls forward, (as seen in Figure 2.4).

Inside the hopper the sand pass over a vibrating grizzle for separation of over-size materials such as stones and roots which are rejected and directly returnedto the mining void. The sand are subsequently sprayed with a high pressurewater jet to break up eventual chunks of clay. The slurry is and fed through arotating trommel which separates the remaining small size rock. The remainingsand and clay slurry are pumped to the wet concentration plant. Where the

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light worthless minerals, called gangue, like quartz are separated form the valu-able zircon and titanium minerals. To break up the clay and form the slurryrequires large amounts of water. Almost any water source can be used to pro-vide the water and water recycling help reduce the withdrawal rates of thesesources. In wet regions with an annual net rainfall, water recycling may besufficient to maintain a water balance within the mining area. In arid regionswith an annual net evaporation, a water source is a necessity. In Australia theuse of saline groundwater puts special demands on the water management. [21]The saline water could damage vegetation and make the soil infertile, if releasedinto previously non-saline areas.

Figure 2.5: Dredge barges and wet concentration plant in an artificial dredgepond. Dredge barge spraying water to erode shores of dredge pond [22]

Dredge mining

The dredge mining technique use floating dredges to extract the sand, which canbe compared to marine dredges used to build ports or deepen canals. Dredgemining basically consist one or more dredge barges and a floating concentrationplant. The floating dredge barges use a high pressure water jet to underminethe shores of the dredge pond to make the sand collapse into the pond wherethe dredge barge use a suction dredge or bucket wheel to extract it, (see Figure2.5). Since the sand is extracted from the pond it is already in slurry formwhen it pass trough a rotating trommel for separation of oversize materials.The remaining slurry is pumped to the floating concentration plant for furthermineral concentration. The dredge barges and concentration plant are typicallyelectric powered. As the dredge barge cuts into the deposit the dredge pondexpands forwards, but as the concentration plant discards its rejects the pond isfilled up behind. This means that the artificial pond migrates forward to followthe deposit.

2.2.3 Heavy minerals concentration

Independent of which mining technique is used the heavy mineral concentrationuse basically the same techniques. The sand and clay slurry from the mine is fed

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through fine screen to remove any remaining rock or roots before it is fed intoa bank of hydro-cyclone separators where the heavier minerals are separatedfrom the lighter clays and slits. A flocculant chemical might be used to speedut the precipitation of clays. This is the only chemical used in the mining andseparation processes. In dry mining the clays and slits are sent to a thickenerwhich recovers the process water and thickens the clay. The thickened clay ispumped to an evaporations pond where the run off water is collected and reused.The remaining dry clay is then stored awaiting rehabilitation. The fact that therejects are directly returned to the mining void in dredge mining removes theneed of tailing ponds used in dry mining, and facilitates a quicker rehabilitationprocess.

Figure 2.6: Left: Bank of spiral separators [3], Right: Spiral separator whereheavy minerals concentrate towards the center of the spiral [3]

The heavy minerals slurry is fed to a constant density tank to facilitate asmooth flow to the following bank of spiral separators. In the spiral separationthe slurry pass multiple parallell and serial fiberglass spirals. The spiral is con-structed so the lighter materials are separated from the heavier by gravitationalforce where the heavier material are concentrated on inside of the spiral and thenon valuable materials (gangue) on the outside, (see Figure 2.6). The spiralsare placed in banks of parallell spirals to increse the total flow. These banksare placed in series to increase the heavy mineral concentration in steps. Theheavy minerals from one spiral pass on to the next spiral and the light mate-rials are fed to a scavenger spiral to extract any remaining heavy minerals, (asseen in Appendix B.2). The wet concentration typically recovers 95% of theheavy minerals in the slurry and the composition of the formed Heavy MineralConcentrate (HMC) is typically 90% heavy minerals and 10% quartz [23].

A wet high intensity magnetic separation (WHIMS) might be used to performan initial separation in which the magnetic minerals are separated from the non-magnetic. The different minerals are dried in separate piles awaiting transportto the Mineral Separation Plant (MSP). The further refinement may take tworoutes. In a dry mining operation, the HMC is put in piles outside to drynaturally to achieve a low enough moisture level to allow easily handling. When

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dry the minerals are transported to the MSP where the valuable minerals in theHMC are separated from each other and the gangue, (see Section 2.3. The MSPmay either be located at the mine site or at a separate site. Larger deposits oftenhave the MSP at the mine site while smaller deposits often share a commonMSP to which the HMC are transported by truck or barge. In Australia itis common with long transports of HMC from mines located several hundredkilometers from the coast to the MSPs located close to major ports.

2.2.4 Radiological concerns

Heavy mineral sand contain Naturally Occurring Radioactive Materials (NORM)such as the elements uranium, thorium and their decay-progenies. These NORMin the sand imposes special radiological considerations during mining, concentra-tion and transportation. In Australia, the uranium and thorium concentrationsin heavy mineral concentrate typically have an activity concentration of 0.8-8.5Bq/g [24] which is just below the 10Bq/g NORM trade restrictions proposedby the IAEA [25]. The Australian Radiation Protection and Nuclear SafetyAgency (ARPANSA) performed a study investigating the radiations exposurein the transports of heavy mineral sand concentrate between mines and mineralseparation plants and shipment to final costumers. The results showed thatthe highest annual exposure for a worker involved in the transports of heavymineral sands in Australia were estimated to be 604 µSv/y [24]. Annual expo-sure to mining personel at an Australian mine were estimated to be 3 mSv/y[26], mostly due to external gamma radiation with a small part from internalexposure form dust inhalation and radon.

Figure 2.7: Heavy mineral mining on North Stradbroke Island [27]

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2.2.5 Mine rehabilitation

Mineral sand mining have been conducted in Australian in over 70 years andwell establihed best rehabilitation principles have been established. Studies ofrehabilitation progress are conducted by the Australian Centre for MineralsExtension and Research (ACMER) [28] for almost 20 years. Studies of rehabili-tations show that there exist methodes for sucessfully rehabilitating a mine siteand reestablishing local species [29]. Since the heavy mineral grade of a depositis typically 10 wt.% only a small fraction of the volume is extracted and over90 % of the materials are returned into the mining void. This mean that themining void can be almost completly backfilled and the former topology can beconstructed.

Except for some radiological concerns, the tailings from heavy mineral sandmining are not hazardous. The tailings from heavy mineral sand mining aredifferent than from most other metal mining in the sense that the tailings fromsand mining are sand, which is already oxidized and unreactive. While tailingsfrom mining of hard rock will crush the rock and expose the unextracted metalsto oxygen and water which may lead to an increade release of metals into theenvironment. Further, ore from hard rock may contain sulphuric minerals whichwhen exposed to oxygen and water will create suphuric acid and create acidmine drainage which will increase the release rate of metalls to water. Since thetailings from mineral sand mining are sand which already have been exposed tothe elements and are already oxidized there are not the same problematic withheavy metal release.

In the case of dredge mining, the dredge pond continuously move forwardfollowing the deposit using the gangue separated from the HMC to backfillthe void. Hence there is no need to store tailings in a special dedicated area.Topsoil and overburden will still have to be stored, although after the initialmine pit is established any further clearing of topsoil and overburden migh beused directly in the rehabilitation. Since the mine void is continuously backfilledthe rehabilitation process can also be carried out continuously, (see Figure 2.8).There is however usually a gap (i.e. active open mining area) between miningand rehabilitation that is significantly larger than indicated by Figure 2.8.

In the case of dry mining, the tailings discarded by the concentration processesare fed back into the mining void via a tailings dam and transport by trucks.Since the tailing are in slurry form there is a need to let it dry before it is easy tohandle. In dredge mining, the water is simply returned to the dredge pond andin dry mining the water are collected from the tailings dam and reused as processwater. Once the material in the tailings dam is dry enough, it is transportedback to the mining void by trucks and the rehabilitation can begin. Once back inthe mining void bulldozers use the tailings to reconstruct the former topology ofthe deposit. When the desired shape has been acquired overburden and topsoilare replaced from their storages or if possible, taken directly from the clearingof new topsoil in the mine path. Clay is mixed with sand and spread on top ofthe dune to create a water absorbing layer to help revegetation.

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Figure 2.8: Mining with integrated rehabilitation [30]

The seeds which were sampled in the preparation for mining, (described inSection 2.2.1), have now either been grown in a plant nursery or are planteddirectly. Saplings grown from the plant nursery are replanted to speed up theregrowth. If the mine is located in a windy region or experience heavy rainfall,extra measures to prevent erosion are needed. These might include the con-struction of wind fencing, spreading of biodegradable bitumen sand stabilizeror spreading of mulch from the cleared vegetation in the mine path. [31] Slowgrowing trees might have to be grown in a plant nurery and replanted as grownspecimens. Dead trees and logs from the clearing might be placed to createcover and nesting possibilities for animals.

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2.2.6 Environmental impacts

The most notable environmental impacts in the zircon mining are the large areasof land required to be stripped of vegetation to uncover the mineral deposits.The destruction of habitats will affect threatened species although the impactscan be minimized if an ambitious rehabilitation program is conducted. Theproblems with the large areas cleared by mining is exacarbated by the fact thatbeach and dunal deposits in costal environments often are key habitats. Costaldunes provide a special environment which is sensitive to invading species suchas weeds, this puts special demands on the rehabilitation.

The fact that most mineral sand deposits are located in costal environments isa source of some controversy for the sand mining industry. Sand mining on theheavy populated Australian east coast have lead to conflict where recreational,environmental and mining interests have opposed each other. Historically, assand mining claimed larger and larger costal areas so did the population growthand environmental conservatists. This lead to the establishment of several pre-seves protecting against sand mining. One of the current controversies are thesand mining on North Stradbroke Island, 30 km from Brisbane [32].

Another notable impact is related to the large energy demand to operate amine. Dredge mining activities typically use electricity as the primary energysource for the dredges and floating HMC-plant. For almost all other machinesdiesel is the primary energy source. Mining requires a diversity of diesel fu-eled machinery such as excavators, trucks and bulldozers. Mineral sands mineslocated far from existing infrastructure may have local diesel power plant togenerate electricity while other mines have diesel powered back up generators.This corresponds to the reported emission shown in Table 2.3

Table 2.3: Top five largest emissions by weight, reported by Australian zirconmining companies [33]

Emission % of facilities reportingParticulate matter 79.3Carbon monoxide 79.3Oxides of nitrogen 79.3Sulphur dioxide 79.3Volatile organic compounds 79.3

2.3 Mineral separation

The mineral separation is where the valuable minerals in the heavy mineral con-centrate are separated from each other, where the zirconium bearing zircon isseparated from the titanium minerals and gangue. The process is unlike mostother metal mining due to the almost complete lack of chemicals in the separa-tion. The processes only rely on the minerals different physical characteristics.For a full process flowchart of the separation refer to Appendix B.4. The mineralseparation can be divided into roughly three stages: (see Figure 2.9).

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• Magnetic separation

• Electrostatic separation

• Gravitational separation

Figure 2.9: Overview of mineral separation

An initial magnetic separation may be performed by the WHIMS in the wetconcentration, (see Section 2.2.3). Other than that the separation of heavymineral sands occur in special Mineral Separation Plants (MSP) either at themine site or at a separate location. Larger deposits which have a long mine lifetypically have their own MSP. For smaller deposits which are typically minedout in a few years the extensive infrastructure of the MSP are shared betweenseveral deposits. The HMC is typically transported by truck and barge from themine site to the MSP. The properties used to separate the minerals are magneticsuseptability , electrical conductivity and specific gravity. The properties of theminerals most commonly found in heavy mineral deposits are shown in Table2.4.

In the first stage of separation the HMC is passed through a rare earthmagnetic roll separator where magnetic minerals are separated from the non-magnetic minerals, see Figure 2.10. The HMC feed enters the magnetic sepa-ration on a conveyour belt. The magnetic ilmenite and leucoxence are pinnedto the belt by the magnet while the non-magnetic minerals such as zircon areunaffected and are thrown clear of the belt.

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Table 2.4: Properties of minerals commonly found in heavy mineral depositsMineral Magnetic Electrical Specific Chemical Formula

Susceptibility Conductivity GravityIlmenite-sulphate High High 4.5-5.0 FeO.T iO2

-chloride High High 4.5-5.0 Fe2O3.3T iO2

Rutile Low High 4.2-4.3 T iO2

Leucoxene Medium Low 3.5-4.1 Fe2O3.T iO2.mH2OZircon Low Low 4.7 ZrSiO4

Monazite Medium Low 4.9-5.3 (Ce,La, Th,Nd, Y )PO4

Staurolite Medium Low 3.6-3.8 Fe2Al9O6(SiO4)4(O,OH)2Kyanite Low Low 3.6-3.8 AlSiO5

Garnet Medium Low 3.4-4.2 (Mg,Ca,Mn, Fe)3(Al,Cr, Fe)2(SiO4)3Quartz Low Low 2.7 SiO2

Cassiterite Low High 7.0 SnO2

Figure 2.10: Magnetic separation concept

In the second stage the non-magnetic minerals are fed through a high tensionroll separator, (see Figure 2.11). The mineral feed pass an ionizing electrodewhere the mineral grains are ionized. The conductive minerals like rutile easilytransfer their charge to the earthed metal roll and lose the ionization. Thenon-conducting minerals like zircon acquire an opposite electrical charge to themetal roll. This leads to an electrostatic pinning effect where the opposite chargenon-conductors and roll are attracted to each other. The non-conductors pin tothe roll surface until they reach the AC wiper electrode where the grains losetheir charge. A plate electrode is used to widen the separation gap by giving astrong lifting effect on the uncharged conductors. The minerals are separatedinto different bins depending on level of electrical conductivity (EC). The zirconrecovery efficiency of this process is typically 90% [23].

In the third stage the non-conductive zirconium bearing mineral is fed througha wet spiral separation for gravitational separations, (described earlier in Section2.2.3). At this point the first crude zircon concentrate is formed. The follow-ing refinement processes intend to increase the grade of the zircon product byremoving additional impurities. A second electrostatic separation removes the

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Figure 2.11: Electrostatic separation concept

remaining rutile or ilmenite and a second magnetic separation remove the re-maining monazite and garnet. Finally a gravitational separation using air orwater tables remove any quartz, kyanite or staurolite to form premium gradezircon.

2.3.1 Radiological concerns

Heavy mineral concentrate is rich in radioactive elements. The main sourceof the radioactive elements are the mineral monazite (Ce,La, Th,Nd, Y )PO4

which in Australia typically contain 5-7% thorium and 0.1-0.3% uranium [26].The concentration of monazite in heavy mineral deposits is typically less than1% although the concentrations may vary significantly between different loca-tions and concentrations of 2-5% are common in Indian beach deposits [34].Monazite is usually considered a problem due to its high content of radioac-tive thorium although monazite is coextracted with zircon in India, where themonazite is used as a source of thorium. Other heavy minerals like zircon alsocontain uranium and thorium trapped within the lattice sturucure of the min-eral.

Raw zircon may contain 200-700 ppm uranium and 200-700 ppm thorium [35].To meet the quality of premium grade zircon the uranium and thorium (U+Th)contents must be kept below 500 ppm. Commercial zircon typically contain350-450 ppm (U+Th) [36]. This is ensured largly by removing monazite inthe mineral separation process. The separation and concentration of monaziteintroduces a waste stream with increased radioactivity. The concetrated wastestream may contain over 30% monazite. This waste is returned to the minevoid and are covered with several meters of overburden in the rehabilitationprocess. The uranium concentrations in the zircon can be compared to the

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Rossing uranium mine in Namibia, one of the worlds largest uranium mineswhich mine a low grade deposit of 300 ppm uranium [37].

Dust containing Natural Occuring Radioactive Materials (NORM) particlesis a health problem for workers in the mineral sands industry. However, focuson dust reduction such as increased use of wet processes have decreased the doseto workers in the Australian mineral sand industry from 16 mSv/y in the early1990’s [38] to less than 1 mSv/y in the early 2000’s [3].

2.3.2 Environmental impacts

Emissions reported by two Australian mineral separation plants are shown inTable 2.5. The emissions include carbon monoxide, oxides of nitrogen, partic-ulate matter, sulphur dioxide and volatile organic compounds which probablyoriginate from the burning of fossile fuels. Some of the particulate matter andthe heavy metals probably occur through dust spreading from the handling ofthe mineral sands. The overall direct emissions from the mineral separationplant are low. When compared to the mines, the mineral separation plant emis-sions are less than the rounding error of the mine emissions, for most substancesreported.

Table 2.5: Example of substances reported from two Australian mineral sepa-ration plants [33]

Substance emitted RecipientCarbon monoxide AirChromium compounds AirFlouride compounds AirOxides of nitrogen AirParticulate matter AirSulphur dioxide AirVolatile organic compounds Air

The major environmental impact from the mineral separation processes isrelated to use of electricity. Other important impacts are the dust from thehandling of the sand and the health effects of dust and radioactive particles.

2.4 Zirconium sponge production

In order to produce zirconium metal from zircon sand the strong zirconium oxidebindings have to be broken by chlorination. The zirconium have to be separatedfrom hafnium because of their almost opposite characteristics in a nuclear re-actor environment. Subsequently, the zirconium have to be reduced into metalform and be distilled to remove impurities to form an almost pure zirconiumspongelike material called zirconium sponge. The zirconium sponge productioncan roughly be divided into; chlorination, zirconium-hafnium separation andreduction, (see Figure 2.12).

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Figure 2.12: Overview of zirconium sponge production

Raw natural zircon typically contain 2 wt.% [9] hafnium which need to beremoved for nuclear zirconium applications. To meet the industry standardsof zirconium sponge the hafnium content have to be below 100ppm [39]. Thefundamental difference between ordinary zirconium metals and nuclear gradezirconium metals are the hafnium content of the metal. Since zirconiums andhafniums extremly similar chemical properties, there is no need to remove thehafnium for appllications in the chemical process industry. However, because ofthe almost opposite physical properties hafnium need to be removed for nuclearapplications.

Natural occurring zirconium is a mixture of 5 stable isotopes with a totalthermal absorption cross section of 0.19 barn. Natural occuring hafnium isa mixture of 5 stable isotopes with a thermal absorption neutron cross sec-tion of 104 barn. This means that hafnium have an almost 600 times greaterprobability of absorbing a thermal neutron than zirconium. In a nuclear re-actor environment hafnium is considered a reactor poison because of the largecross-section. Hafnium is actually used in control rods to absorb neutrons. Toimprove the neutron economics in the nuclear reactor, i.e. losing fewer neutrons,the naturally occurring hafnium have to be removed. This is performed in thezirconium-hafnium separation process, (see Section 2.4.1).

Zirconium and hafnium have very similar chemical properties. They havethe same valences and their ionic radii differ by only 2% due to the lanthanidecontraction [40]. This make the separation of the two metals very difficult.

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There exist several more or less commercial techniques for the separation ofzirconium from hafnium. The major techniques can be divided into liquid-liquid solvent extraction, extractive distillation and ion-exchange separation.However, only the liquid-liquid extraction and the extractive distillation will bedescribed in detail in this report since they are the techniques used by the majorwestern zirconium producers.

2.4.1 Zirconium-hafnium separation process

Both the liquid-liquid extraction and the extractive distillation require the zir-conium and hafnium to be chlorinated to form zirconium and hafnium chloride(ZrCl4,HfCl4). The raw zircon sand is fed to a fluidized bed carbo-chlorinatorwhere the zircon reacts with coke and chlorine at temperatures of 1200◦C tofrom the Zr,Hf,Si-tetrachlorides and carbon monoxide, according to 2.1.

ZrSiO4, (HfSiO4) + 4 Cl2 + 4 C −−→ ZrCl4 + SiCl4, (HfCl4) + 4 CO (2.1)

The Zr,Si,Hf-tetrachloride fumes are condensed to remove the silicon tetra-chloride which condense at higher temperatures than the zirconium and hafniumchlorides [41]. The silicon tetrachloride can be used in the production of puresilicon for the semiconductor industry. The Zr,Hf-tetrachlorides are condensedand are ready for zirconium-hafnium separation.

Extractive distillation

Extractive distillation uses a counter flow technique with a column of moltensalt with for the separation. This technique is currently only used in France[42]. The process use a column of molten potassium chloroaluminate (KAlCl4)salt which is heated from below. The zirconium and hafnium chlorides aredissolved by the KAlCl4 solvent at 350◦C [43]. The solvent are circulated fromtop to bottom in a column while the zirconium-hafnium chloride fumes rise frombottom to top. The rising vapor is progressivly enriched in hafnium chloridesand the flow going down are enriched in zirconium chlorides. The enrichedzirconium chlorides are condensed and extracted. The hafnium chlorides arealso extracted and are further processed in similar ways to the zirconium toproduce hafnium metal. The zirconium separation efficiency of this process is98% [43].

Liquid-liquid extraction

The liquid-liquid extraction exists in several forms using different solving agents.The major techniques today are the tributyl phosphate nitric acid (TBE-nitrate)process, currently used in India [44] and the methyl isobutyl ketone (MIBK)process used in USA [45]. The MIBK process allows for extraction of bothzirconium and hafnium but the TBP-nitrate process only allows extraction ofzirconium. In this report only the MIBK process will be decribed in detail. Fora full flowchart representation of the MIBK process refer to Appendix B.8 andB.9

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The methyl isobutyl ketone ((CH3C(O)CH2CH(CH3)2) liquid-liquid extrac-tion is a complex process with a lot of chemicals and process stages. Onlythe most significant steges will be described here. The process starts with thehydrolization of the zirconium and hafnium chlorides, according to 2.2).

(ZrHf)Cl2 + H2O −−→ (ZrHf)OCl2 + H2 (2.2)

The zirconium and hafnium oxychlorides ((Zr,Hf)OCl2) are mixed with am-monium thiocyanate (NH4SCN) and MIBK (CH3C(O)CH2CH(CH3)2). Theoxychlorides complexes with ammonium thiocyanate to form (Zr,Hf)O(SCN)2.The Zr and Hf complexes have different solubility in the MIBK and are sep-arated using a column with counter flow liquid-liquid extration. The hafniumcomplexes end up in the organic phase which floats to the top and the zirconiumin the aqueous phase in the bottom. The hafnium is from this point extractedusing the same processes as for the zirconium and will not be described ex-plicitly. The extracted zirconium complexes are sent to a second column forfurther separation. The zirconium complexes are extracted and re-chlorinatedto zirconium oxychloride (ZrOCl2), using hydrochloric acid (HCl) to remove theammonium thiocyante.

The ammonium thiocyanate is scavenged and reused in the process. At thispoint the zirconium typically contain less than 50 ppm hafnium [43]. Thezirconium oxychloride is precipitated using sulphuric acid (H2SO4) to forma zirconium sulphate complex (Zr5O8(SO4)2 ·mH2O). Ammonium hydroxide(NH4OH) is added to the complex to form zirconium hydroxide (Zr(OH)2)which are calcined at 1000◦C to form dry zirconia (ZrO2). The zirconia iscarbo-chlorinated to form zirconium chloride using the same process as above,(see 2.1). The final zirconium chloride is sent on to the zirconium sponge pro-duction process. The zirconium separation efficiency of this process is 89% [43].

2.4.2 Zirconium sponge production process

In the production of zirconium alloys the production of zirconium sponge isthe first stage where the zirconium exist in metal form. The hafnium freezirconium tetrachloride is reduced into a porous spongelike metal, hence thename zirconium sponge. The zirconium sponge production use either zirconiumchloride (ZrCl4) or zirconium oxychloride (ZrOCl2 · 8 H2O) as zirconium source.However, only the use of ZrCl4 will be described in detail. The zirconiumchloride is reduced by magnesium in a furnace at 800-850◦C in the so calledKroll process, according to 2.3.

ZrCl4 + 2 Mg −−→ Zr + 2 MgCl2 (2.3)

The resulting spongelike material, called zirconium sponge, is purified byheated vacuum distillation where the magnesium chloride is removed. Themagnesium chloride is evaporated, extracted and recycled by dissassociatingthe magnesium from the chlorine by electrolysis, according to reaction 2.4.

MgCl2 −−→ Mg + Cl2 (2.4)

35

Figure 2.13: Left: Raw zirconium sponge [46]. Right: Crushed zirconium sponge[47]

The magnesium is reused in the Kroll process and the chlorine are reusedin the carbo-chlorination processes. The raw zirconium sponge is mechanicallycrushed into small pieces for easier handling, (see in Figure 2.13). The smallpieces are packed in drums and transported to zirconium alloy producing facil-ities. The few companies which produce zirconium sponge also produce zirco-nium alloy materials but not all companies producing zirconium alloy materialsproduce their own zirconium sponge, (see Appendix A.2).

2.4.3 Environmental impacts

When analysing the environmental impacts from the zirconium sponge produc-tion it have become evident that sponge production is an industry with fewactors who are very protective of their proprietary processes. No detailed infor-mation could be aquired on which chemicals that are recovered and reused in theprocesses. It is hard to estimate the environmental impacts only based on thechemicals and processes used. However, when looking at two American spongeproducing facilities, many of the chemicals described in this section appear intheir emission reports sent to the US Environmetal Protection Agency (EPA).The reports are published in the Toxic Release Inventory database run by theEPA [48]. However since facilities with sponge production also may containlater stages in the manufacturing of zirconium alloys it difficult to be certainthe emisions originate from the zirconium sponge production, since no data onproduction levels or production mix were available. The MIBK emissions how-ever most probably originate from the Zr-Hf separation. Examples of typicalemissions from two American zirconium sponge producers are shown in Table2.6.

The ammonia in Table 2.6 may originate from the ammoinum thiocyanate(NH4SCN), the chlorine and hydrochloric acid may originate from the clorina-tion, the MIBK is certainly from the MIBK-extraction and the nitrates mayoriginates from the ammonium thiocyanates.

36

Table 2.6: Example of emissions reported from two American and one Frenchzirconium sponge producer [48] [49]

Substance emitted RecipientAmmonia Air & WaterChlorine AirHydrochloric acid AirMethyl isobutyl ketone Air & WaterNitrate compounds Water

There are potentially large differences in environmental impacts from the twodifferent zirconium-hafnium separation techniques. The extractive distillationonly use one major chemical where the liquid-liquid extration uses several. Thechemicals in the MIBK process are known to have its disadvantages. The cre-ation of toxic gases like hydrogen sulphide (H2S) and hydrogen cyanide (HCN)in contact with ammonium thiocyanate [50]. The MIBK solubility in water andthe MIBK vapour to air and high concentrations of ammonium and cyanides inwaste [45].

Perhaps the most serious environmental concern is the radioactive residuethat are concentrated in the waste streams in the zirconium-hafnium separation.The radioactive waste treatment process still remain a question mark sincethere were no material available describing the treatment and handeling of thiswaste. There exist methodes for extracting the uranium into a saleable uraniumproduct [51]. This would however introduce new demands and legislation onthe producers. No references to uranium being produced by this method werefound. As previously mentioned (in Section 2.2.4) the zircon may have the sameuranium conentration as the low grade uranium ore. The final sponge typicallycontain less than 3 ppm uranium [43]. The radioactive waste stream containingthe uranium and thorium may have a severe environmental impact if not treatedand disposed correctly. Unfortunately no information on treatment and disposalcould be obtained.

The magnesium reduction of zirconium chloride (Kroll process) and the fol-lowing heated vaccum distillation requires high temperatures and vaccum cham-bers which are energy intensive.

2.5 Zircaloy ingot production

The manufacturing of zirconium alloy products use zirconium sponge as the rawmaterial. The first stages in the production of all zircaloy materials require themixing of the metals to attain the right composition of metals in the alloy.

2.5.1 Zirconium alloy ingot production processes

The production of zircaloy ingots starts from the mixing of zirconium spongewith the alloying metals. This is where the final composition of the alloy is de-cided, the subsequent stages may only slightly alter the chemical composition of

37

Figure 2.14: Overview of zircaloy ingot production

the alloy by introducing impurities, mainly oxygen and nitrogen. The chemicalcomposition of two of the most common zirconium alloy materials are shown inTable 2.7. Because zirconiums high melting temperature of 1852◦C and highoxidization at these temperatures zirconium is melted in vacuum arc furnaces.

Table 2.7: Chemical composition of the two most common zirconium alloysElement Zircaloy-2 Zircaloy-4

% %Zirconium 97.7-98.5 97.9-98.4Tin 1.2-1.7 1.2-1.7Iron 0.07-0.2 0.18-0.24Chromium 0.05-0.15 0.07-0.13Nickel 0.03-0.08 -Oxygen 0.1-0.14 0.1-0.14Hafnium 0.01 0.01

The alloy and sponge mix is pressed into a semi cylindrical briquette usinga hydraulic compacting press. The briquettes in their semi cylindrical formare welded together two and two to form a full cylinder using electron beamwelding (EBW). The welding use a electron beam in a vacuum chamber to weldthe cylinders together. The cylinders are subsequently welded together to form

38

Figure 2.15: Concept of zirconium alloy mixing, compacting and production ofconsumable electrode

a longer rod. Recycled scrap from later stages of the production are also pressedinto briquettes and comprise of up to half of the cylinders at this stage. Thecylinders are welded together with approximately every second cylinder beingfresh material and every second being recycled material to facilitate a uniformdistribution of the alloying ingredients. The final cylinder is called a consumableelectrode and is basically a gigantic welding rod, a few meters long and weighingseveral tonnes.

Figure 2.16: Vacuum arc remelting process

The consumable electrode is melted in a vacuum arc remelting (VAR) furnacewhich is basically a gigantic welding machine. The consumable electrode isfastened in the top of the furnace and the electrode is put close enough to thebottom of the water cooled copper mold to enable a spark gap, (see Figure

39

2.16). The copper mold is filled with recycled zirconium scrap in the bottomto avoid spark from the electrode to the copper which would introduce coppercontaminants. Several kilo ampere of DC-current is fed through the electrodewhich is continuously fed downwards to keep a static spark gap between theelectrode and the molten zirconium forming at the bottom. To prevent sparksfrom the electrode directly to the copper the distance from the electrod to themold is larger in diameter than the spark gap. This is important since the largecurrents used are sufficient to burn a hole in the copper mold in just a fewseconds. Since the copper mold is water cooled this would lead to injection ofwater into the over 2000◦C molten zircaloy where the water would turn intosteam. This would lead to an initial steam explosion followed by a hydrogenexplosion since the zirconium oxidization occurring at these temperatures wouldrelease large amounts of hydrogen. During normal operation the vacuum in thefurnace is kept below 1 Pa and the fumes releases in the melting process are fedthrough a water scrubber before releasing to air.

When the hot ingot have cooled down to handling temperatures it is cutup into cylindrical briquettes and once again welded together using a EBWmachine. This is to mix the different sections of the ingot and get a moreuniform melt in the next round of VAR. This process of melting, cutting andwelding is repeated three times or more until final alloy uniformity is reached.When the ingot alloy composition is sufficiently uniform the ingot is cut andmachined into its final dimensions, removing sharp edges at the top en bottom ofthe ingot and removing any surface copper contaminants from the mold. Afterthis the ingot is ready to be forged into whatever form is required. The ingotmay be forged into billets for bar and tube production, sheet for spacer andchannel production, wire for spacer production etc., (as seen in Figure 2.17).However, only the tube production will be described in this report.

Figure 2.17: Production of zirconium alloy materials

2.5.2 Environmental impacts

The major impacts from the ingot production process is related to the electricityrequired to operate vacuum arc remelting furnace, the electron beam weldingmachine and related vacuum pumps. The vacuum arc melting produces minor

40

ammounts of metal fumes which are evacuated through the vacuum pumps andpassed through a scrubber before release into atmosphere. The direct emissionsrelated to these processes appear to be low.

2.6 Zircaloy tube production

Zircaloy tube production can roughly be divided into forging of the ingot, extru-sion and pilgering as described in Figure 2.18. Through all these stages there ishigh requirements on the molecular structure of the zirconium, since the struc-ture is the base for the corrosion resistance. Hence the production of nucleargrade ziraloy tube require additional processing than conventional zirconiumalloys.

Figure 2.18: Overview of zirconium tube production

2.6.1 Zircaloy tube production processes

The first step in zircaloy tube production is the forging of the ingot. The forgingrequire the heating of the zircaloy material into the α and β phases. In the α-phase the metal recrystalize and the metal lattice is hexagonal. In the β-phasethe lattice structure change into body centered cubic. In general the plasticityand workability of the material increase with temeperature but so does theoxidation. To minimize the oxidation and keeping the oxygen levels of the finalproduct low the temperature is kept as low as possible while still maintaning

41

sufficient workability of the material. To begin the forging the ingot is heatedin a furnace to about 1050◦C to reach the β-phase in which the ingot is forgedto a round log with a diameter of approximately 350 mm [43]. For the forgingdown to the final dimension the log is reheated in the furnace to about 750◦Cto reach the α-phase. In this phase the fusion structure can be broken downto homogenize structure of the log. The log is subsequently forged down to itsfinal diameter of approximately 180 mm [43]. After cooling the log is cut upinto smaller cylinders called billets which are approximately 400 mm long. Thebillets are subsequently pierced using a drill to form hollow billets.

Figure 2.19: Left: Preheating of zirconium ingot in a furnace, Right: Reducingzirconium ingot diameter by forging

To achieve the proper corrosion resistance the hollow billets are beta-quenched.Beta-quenching is a process where the metal is heated to its β-phase and thenrapidly cooled down. The beta-quenched billet is machined to its final dimen-sions using lathes. The final hollow zircaloy billet is extruded to tube shells.The extrusion requires special lubricants or coatings on the billets. The coatingneed to be ductile, reduce friction and prevent oxidization of the zirconium.Commonly used coatings are glass or copper which are applied to the hollowbillets [52]. In the extrusion process the hollow billet is pressed through a dieto reduce the diameter and elongate the billet into a seamless tube called tubereduced extrusion (TREX), (see Figure 2.20).

The crude extruded tube shells (TREX) are straightened by roll straightening.The ends are cut off and the cuts are smothened to remove burrs. The cut offend pieces are recycled and used either in the VAR furnace or compacted intobriquettes. The TREX have to be cleaned in acid baths to dissolve the coatings,this acid bath process is called pickling. For copper coatings nitric acid is used[52].

The tube shells diameter is reduced in an inintial cold pilgering where a greaselubricant is used. The reduced tube which is elongated is cut into lenght andthe discarded end pieces are recycled. The cut tubes are pickled in acid baths ofhydrogen flouride and nitric acid to remove pilgering grease. The cold pilgeringadds strain to material which need to be removed by a heat treatment calledannealing. The annealing requires the zirconium to be heated up to 750◦C to

42

Figure 2.20: Extrusion process

reach the α-phase where the material recrystalize and built up strain is released.The tubes are annealed in a vacuum furnace to avoid oxidization. Subsequentto annealing the tubes are straightened using roll straightening in which thetubes are rolled on large metal cylinders. These steps of cold pilgering, pickling,annealing and roll straightening are performed three or more times until thefinal dimensions of the tube is reached.

When the tubes have been reduced to their final diameter they are sand-blasted to smoothen the surface. A final pickling is performed to remove anycontamninats before the tubes are cut into final lenghts and shipped to thenuclear fuel manufacturing plant.

Figure 2.21: Cold pilgering, pickling, annealing and straightening process

2.6.2 Environmental impacts

The major impacts from the zirconium tube production is related to use of acidsin the pickling. Unfortunately this study were unable to analyze waste handel-

43

ing and only reported emission could be obtained. Some of the most notableemissions are shown in 2.8. However, since some of the facilities producing zir-conium alloy tube also may produce other products it is difficult to be certainthat all emissions are related to the zirconium alloy tube production.

Table 2.8: Example of emissions reported from two American and one Frenchzirconium alloy tube producer [48] [49]

Substance emitted RecipientChlorine AirHydrogen flouride AirHydrochloric acid AirNitrate compounds WaterNitric acid Air

The releases of hydrogen flouride, nitric acid in Table 2.8 are most probablyfrom the pickling processes. The releases of chlorine, hydrochloric acid andnitrate compounds are probably also related to the pickling processes. Theproduction of zirconium alloy tubes require several heating stages which areenergy consuming. Depending on the energy source used for the different heatingstages the environmental impact may vary significantly depending on if it iselecticity from water power or directly burned fossile fuels used.

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Chapter 3

LCA of zirconiumproduction

To be able to quantitatively describe the environmental impacts of the produc-tion of nuclear grade zirconium alloy materials, a life cycle analysis (LCA) wascarried out. The goals of this LCA study were to determine the emissions andresource consumption for the production of 1kg of zirconium alloy tube. Theaim was to be able to compare the results with the current LCA from Vatten-fall’s Forsmark nuclear power plant (NPP) found in the Forsmark EPD [53].To analyze the impact zirconium alloy production have on the environmentalimpacts of the production of 1 kWh of electricty. Unfortunately only the zirconproduction could be analyzed in detail, due to lack of data form the zirconiummetall producing industries.

The emissions include lots of different substances with different environmen-tal effects. To be able to compare and communicate the the effects of a largenumber of substances their effects are classified into a few environmental impactcategories (EIC) such as greenhouse gases, acidifying substances etc. The EICprovides a plattform for easy comparison of different activities. The generalconcept of how environmental impact categories are explained in Figure 3.1.Substances may affect several different EIC and have different impacts on dif-ferent EICs. I.e. Sulphur dioxide is both an ozone creating substance and anacidifying substance. All substances affecting an EIC are muliplied by a cor-responding weight factor and are summed to calculate the total environmentalimpact.

The data needed to quantitatively determine the impacts from the productionof any product are the emissions from the production, the resource consumptionand the production levels. However, since companies produce multiple productsthe emissions have to be allocated amongst the products. This allocation canbe performed in several different ways, the method chosen by Vattenfall andused in this study is the allocation by market price. To be able to perform thisallocation the total production of different products and their respective priceshave to be known.

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Figure 3.1: Concept of environmental impact categories

3.0.3 Data sources

To gather data on the production, emissions, resource consumption, productionmix and product prices the idea came to contact companies involved and sendout a survey where they were to answer questions about their environmentalperformance. Regrettably there was a very low interest for this kind of studyin the industry when first approached. After repeated contact attempts andrejections only a few zircon mining companies showed any interest in joiningsuch a survey. All with the concern only to join if the number of participantswere large enough to allow them not be singled out to avoid disclosing prorietarydata. There were no replies from the zirconium sponge and alloy industries.Unfortunately the number of responses were to low to statistically guaranteethat no single company could be identified and the survey were discontinued.

Fortunately there are a lot of statistics available online through companyannual and environmental reports and governmental agencies around the world,at least in the countries which have more transparent policies. The types ofsources available are; environmental protection agencies to which companieshave to report emissions, geological surveys which keep track on production ofminerals and mineral prices, company annual and environmental reports whichmay include emissions, resource consumption and production. This study isbased entirely on this kind of publicly available sources. However the study is

46

limited to include only the mining and production of zircon, since there were noavailable data on production levels or product prices from the zirconium spongeand alloy producers.

3.1 LCA of zircon production

To perform a LCA of zircon production six companies were analyzed, four inAustralia, one in Mozambique and one in South Africa, (as shown in Table3.1). For the Australian companies there exsit facility level emission reportsas well as company annual reports with company total production levels fordifferent minerals. Since no facility level production figures could be obtainedthe emissions on the facility level emissions were summed to form companytotal emissions to enable comparison with company total production levels.For the Mozambiqan and South African companies their annual report containsome emissions and resource consumption along production levels, as seen inAppendix C. The company total emissions, production and product prices wereused to calculate the emissions allocated to the production of 1 kg of zircon.

Table 3.1: Zircon mining companies analyzed in the LCA studyCompany CountryAustralian Zircon AustraliaBemax Resources Limited AustraliaExxaro South AfricaIluka Resources AustraliaKenmare Resources MozambiqueTiwest Australia

3.1.1 Data sources

The National Pollutant Inventory (NPI) [33] is database on emissions fromAustralian facilities. The database is run by the Australian government De-partment of Sustainabiity, Environment, Water, Population and Comminuties(DSEWPaC) [54]. Australian industrial facilities which have emissions overcertain thresholds or handle hazardous substances over certain volumes are re-quired by Australian law to annually report their emission to the NPI database.The emission reports contain facility esitmates on the substances tripping thereporting thresholds, for any of the 93 substances being monitored. The sub-stances being monitored are selected based on environmental effects, humanhealth effects and exposure. However, greenhouse gases such as carbon dioxideand ozone depleting substances are not included in the NPI data.

The data on resource consumption and greenhouse gas emissions are fromthe three companies Iluka Resources, Exxaro and Kenmare Resources annualreports. These three companies were the only who are publishing quantitativedata on their environmental performance in their annual reports. The datapublished include energy consumption by fuel, CO2 emissions and water con-sumption. Data on mineral prices are from the United States Geological Survey

47

(USGS). The USGS collect data on the import and export prices of mineralcommodities in the US. The pricing data are obtained from the Mineral YearBook [55] published by the USGS.

The comodity prices and the production levels are used to calculate the shareof zircon production by market value according to 3.1. The share of zirconiumproduction are used to allocate the emissions and resouce consumption betweenthe different minerals produced. Company by company raw and intermediatedcalculated data are shown in Appendix C.

Zircon share =ProdZr · PriceZr

ProdZr · PriceZr + Prodother · Priceother(3.1)

The formula used to calculate the emissions or resource consumption of 1kg of zircon produced i.e. the amount of substance (emissions or resource) perkilogram of zircon produced are given in 3.2.

Substance per 1 kg zircon produced =Substancetot · Zircon share

ProductionZr(3.2)

The different companies substance utilization (emissions and resource con-sumption), shown in Appendix C, were combined using a weighted average tocalculate the average industry emissions and resource consumption shown inTable 3.2. For each parameter in Table 3.2 the share of world production ofzircon included in the sample data is displayed.

Table 3.2: Emissions and resource consumption for the production of 1 kg zirconin Australia, based on 2009 year production

Impact category Unit Impact per Sample datakg zircon % of worldproduced production

Greenhouse gases [kg] CO2-eq 9.22 E-01 37%Acidification potential [kg] SO2-eq 1.00 E-03 34%Photochem. ozone-creation potential [kg] Ethene-eq 2.56 E-04 34%Eutrophication potential [kg] Phosphate-eq 2.05 E-04 34%Particulate matter to air [kg] 1.52 E-02 34%Water usage [kg] 2.29 E+01 37%Energy usage [kWh] 2.06 E-03 35%

3.1.2 Impact on the LCA for Forsmark NPP

To analyze the impact of zircon production on the life-cycle of a nuclear powerplant (NPP). The results in Table 3.2 were used in the calculations of LCA fromthe EPD for Forsmark NPP [53]. The emissions and resource consumption forthe production of 1 kg zircon were multiplied by the kilograms zircon requiredin the production of 1 kWh electricity from the EPD, the results are shown inTable 3.3.

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Table 3.3: Emissions and resource consumption for the production of 1 kWhelectricity form Forsmark NPP excluded zircon production compared to emis-sions and resource consumption contribution from the zircon production

Impact category Forsmark emissions Forsmark emissions % Increasezircon excluded from zircon

productionGreenhouse gases[kg] CO2-eq 6.43 E+00 2.85 E-03 0.0443%Acidification potential[kg] SO2-eq 4.75 E-02 3.09 E-06 0.0065%Photochem. ozonecreation potential[kg] Ethene-eq 5.63 E-03 7.91 E-07 0.0141%Eutrophication potential[kg] Phosphate-eq 4.90 E-03 6.32 E-07 0.0129%Particulate matterto air [kg] 1.52 E-02 1.11 E-05 0.0729%Water usage [kg] 9.77 E+03 7.07 E-02 0.0007%Energy usage [kWh] 2.50 E-02 6.43 E-06 0.0257%

None of the parameters investigated in the zircon production contributes bymore than 0.1%, (as seen in Table 3.3). This implies that the zircon productionas a part of the zirconium alloy production have an insignificant impact on EPDfor Forsmark NPP.

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Chapter 4

Discussion

During the work with this report the most suprising findings are not the infor-mation actually found but rather the complete lack of information in certainareas. For example, China have approximatley 10% of the world production ofzircon, yet almost information no zircon production in China could be found.Overall, it is easy to find information on the mining processes but almost allinformation found are from a small set of companies, most of them located inAustralia. When it comes to the zirconium metal manufacturing companies thecase is the opposite.

The zirconium metal manufacturing industry is characterized by a situationwith production overcapacity and new companies emerging and trying to es-tablish. The zirconium metal industry are very concerned about proprietarydata leaking to competitors and hence gathering information on the industryprocesses have been very difficult. There are currently two major techniques ofseparating zirconium from hafnium used in the western world where the newerextractive distillation technique seem to have lower emission of chemicals thanthe older liquid-liquid extraction. The direct emissions of the zirconium spongeproduction are related to the solvents and acids used in the zirconium-hafniumseparation.

The production of zirconium sponge, ingots and tubes are probably moreenergy intensive than the zircon mining due to all the heating stages in themelting, forging and annealing stages. Since most energy used in these stagesare from electrcity the environmental impacts differ from country to country.France with a high percentage of nuclear electricity will have different emissionsthan the USA with a high percentage of fossile fuels. This would also implythat the zirconium alloy production might have higher emissions related to theburning of fossile fuels than the zircon mining. Unfortunately this could not beanalyzed in detail.

LCA data sources The National Pollutant Inventory (NPI) data contain fa-cility level emissions but production levels found are given on company level.This means that in order to calculate company emissions the facility level emis-sion have to be summed. This however introduce a problem since it might be

50

difficult to know if a certain facility is involved in the zircon production chain.The list of facilities found in Appendix C are the facilities which have beenidentified or assumed to be involved in the zircon production at one or anotherstage. The list involves mines not yet in production or in rehabilitation as wellas ports facilities for shipping and storing zircon products.

Uncertainties in LCA calculations The emissions reported to the NPIdatabase are best estimates from the companies and are considered accurate.The reported production levels are either directly from company annual reportsor governmental agencies and are therefore considered accurate. The allocationof emissions by market price introduce the uncertaities of not knowing the actualprices paid for the minerals, the matching of production reported by companiesto prices monitored by the USGS are not straight forward. There are a fewassumptions on the prices of different minerals as shown in the footnotes inAppendix C. These assumptions are best guesses on price levels for the chlorideand sulphate slag, pig iron, scrap iron and secondary ilmeninte. Comparingleucoxene to ilmenite is conservative since leucoxene usually is considered ahigher value mineral.

Further, only the average price levels for production in Australia and importsto the USA were available which further might reduce the accuracy of the prices.Overall the allocation of emissions by marketprice is not that sensitive to errorsin prices since the high price of zircon. For most companies the economic im-portance of zircon over the other minerals are evident, and for most companieshave a zircon share of sales of over 50%, as seen in C. Since the zircon share ofsales is so high an relative high error in the price of the other minerals wouldhave a relative low impact on the emissions allocated to the zircon production.

51

Chapter 5

Conclusions

There is almost no use of chemicals in the mining and mineral separation pro-cesses. The minerals sand are almost entirely separated using physical ratherthan chemical methods. The direct emissions from mining are mainly related tothe use of fossile fueled machinery and disel generators as well as some spreadof heavy minerals through spread of dust. The major resource consumptionsfor the mining operations are the large amounts of energy and water required.

Zircon mining differs from other types of metal mining as there are no prob-lems with acid mine drainage from tailings, and mined areas can often be re-shaped back into their old topology. The large environmental impacts are thevast areas cleared for mining which inevitably leads to large destruction of nat-ural habitats, often in exposed costal areas. One concern though is that dunaldeposits in costal areas are often habitats with a special biodiversity. This re-quires special consideration on the operation and rehabilitation meassures toprotect local, maybe endangered species. On the other hand the rehabilitationprocesses are well developed and used through out the industry. After the initialregrowth phase the lasting impacts to the landscape is relatively small.

Heavy mineral concentrates contain naturally occuring radioactive materials(NORM) which imposes radioactive protection meassures and the overall dosesto personel and public are well within regulatory boundaries. Mineral separationproduce concentrated NORM which are backfilled into the mining void andcovered by several meters of overburden. Concentrated zircon contain as muchuranium as low grade uranium ore. The uranium and thorium in zircon isextracted in the zirconium-hafnium separation and the final zirocnium spongecontain almost no uranium or thorium. This means that somewhere in theseparation stages there must occur a waste stream enriched in uranium andthorium with concentrations similar to those in an uranium mine. The wastecould be used as a source of uranium and thorium [51] but there are no sourcesfound if this is performed or if the waste stream is just disposed of.

The major direct emissions from the zirconium metal manufacturing industryare related to the use of acids in the pickling processes. Other major emissionmight occur due to the large energy demand of the different heating proceses.

52

The production of zirconium sponge, ingots and tubes are potentially moreenergy intensive than the zircon mining and might have higher emissions ofgreenhouse gases.

A licecycle analysis for the zircon mining was carried out. The result fromthe zircon mining were compared to Environmental Product Declaration forForsmark NPP which showed that zircon mining have a less than 0.1% impacton all analyzed parameters in a lifecycle analysis for electricity from nuclearpower.

5.1 Further work

This study was unable to get data on resource consumption other than a fewparameters from a few zircon mining companies. Any further study should tryto obtain first hand data on resource consumption from the companies involvedin the whole production chain from zircon mining to zircaloy tube production.Emission reports were only found for a few contries with transparent governmentagencies. Any further study should try to obtain first hand data on emissionsfrom a more diversified set of countries and companies.

This study was unable to obtain information on production, waste treat-ment and emission mitigation measures from the zirconium sponge and metalmanufacturing industry. Any further study should try establish good lastingrelations with zirconium metal producing companies and have the time andpatience needed to allow for the long process of getting their attention and re-cieving an answer.

Questions that remain to be answered:

• How is the radioactive waste from the Zr-Hf separation treated and dis-posed of?

• How are the acids in the pickling processes treated and disposed of?

• What are the production and price levels of the zirconium metal manu-facturers?

• What is the resource consumption of the different production stages?

• How does the environmental performance differ between countries withdiffrent environmental regulations?

53

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kenmareresources.com, 2009.

57

Appendix A

List of companies

Table A.1: List of zirconium mining companiesCompany Operating country WebsiteAlkane Resources Australia www.alkane.com.au

Australian Zircon Australia www.australianzircon.com.au

Millenium Inorganic Brazil www.cristalarabia.com

Donald Mineral Sand Australia www.donalmineralsands.com.au

DuPont USA www2.dupont.com

Gunson Resources Australia www.gunson.com.au

Matilda Zircon Australia www.matildazircon.com.au

Mineral Deposits Australia www.mineraldeposits.com.au

Sibelco Australia www.sibelco.com.au

Doral Mineral Sands Australia www.afm.com.au

Bemax Resources Limited Australia www.bemax.com.au

Kenmare Resources Mozambique www.kenmareresources.com

Iluka Resources Limited Australia, USA www.iluka.com

Industrias Nucleares do Brasil Brazil www.inb.gov.br

Richards Bay Minerals South Africa www.rbm.co.za

Titanium Corporation Canada www.titaniumcorporation.com

Tiwest Australia www.tiwest.com.au

Exxaro South Africa www.exxaro.com

Kerala Minerals and Metals Ltd India www.kmml.com

Beach Mineral Company India www.bmcindia.net

Indian Rare Earths Limited India www.irel.gov.in

V.V. Mineral India www.vvmineral.com

Kemdel India www.kemdel.org

Eurochem Russia www.eurochem.ru

Titanium Resources Sierra Leone www.sierra-rutile.com

58

Table A.2: List of zirconium sponge manufacturersZirconium sponge producers Operating country WebsiteATI Wah Chang USA www.wahchang.com

Areva/Cezus France www.areva.com

Chepetsky Mechanical Plant Russia www.chemz.net

Jingan Hi-Tech China www.chinazrchem.com

Nuclear Fuel Complex India www.nfc.gov.in

Westinghouse Electric Company USA www.westinghousenuclear.com

Table A.3: List of zirconium alloy manufacturersZirconium alloy producers Operating country WebsiteATI Wah Chang USA www.wahchang.com

Areva/Cezus France www.areva.com

Chepetsky Mechanical Plant Russia www.chemz.net

Fine Tubes Limited UK www.finetubes.co.uk

Global Nuclear Fuel USA www.gepower.com

Jingan Hi-Tech China www.chinazrchem.com

Korea Nuclear Fuel Company Korea www.knfc.co.kr

Nuclear Fuel Complex India www.nfc.gov.in

Posco Korea www.posco.co.kr

Sandvik Sweden www.sandvik.com

Westinghouse Electric Company USA www.westinghousenuclear.com

59

Appendix B

Production flowcharts

60

Figure B.1: Zircon mining flow chart

61

Figure B.2: Wet concentration plant flow chart (1/2)

62

Figure B.3: Wet concentration plant flow chart (2/2)

63

Figure B.4: Mineral separation plant flow chart (1/2)

64

Figure B.5: Mineral separation plant flow chart (2/2)

65

Figure B.6: Zirconium-Hafnium separation flow chart (1/4)

66

Figure B.7: Zirconium-Hafnium separation flow chart (2/4)

67

Figure B.8: Zirconium-Hafnium separation flow chart (3/4)

68

Figure B.9: Zirconium-Hafnium separation flow chart (4/4)

69

Figure B.10: Zirconium sponge production flow chart (1/1)

70

Figure B.11: Zirconium ingot production flow chart (1/1)

71

Figure B.12: Zirconium tube production flow chart (1/4)

72

Figure B.13: Zirconium tube production flow chart (2/4)

73

Figure B.14: Zirconium tube production flow chart (3/4)

74

Figure B.15: Zirconium tube production flow chart (4/4)

75

Appendix C

LCA study

Table C.1: Australian Zircon Emissions 2009 [33]Substance Emissions [kg]Particulate matter 6.77 E+05Sulphur dioxide 2.16 E+01Nitrogen oxides 5.37 E+04NMVOC (unspecified) 5.07 E+03

Acidifcation Potential(a) 2.69 E+04Eutrophication Potential(b) 6.98 E+03Photochem. Ozone Creation Potential(c) 5.40 E+04(a) (Nitrous oxides * 0.5) + (Sulphur dioxide * 1)(b) (Nitrous oxides * 0.13)(c) (Nitrous oxides * 1) + (NMVOC * 0.048) + (Sulphur dioxide *

0.028)

Table C.2: Australian Zircon Production 2009 [56]Substance Production [tonnes]Ilmenite 798Rutile 2380Zircon 9553

Zircon share(a) 86.5%(a) Zircon value of total production, calcu-

lated using prices from Table C.18

Table C.3: Australian Zircon Facilities 2009 [33]Facility LocationAustralian Zircon Mindarie, SA

76

Table C.4: Bemax Resources Limited Emissions 2009 [33]Substance Emissions [kg]Particulate matter 1.88 E+06Sulphur dioxide 7.40 E+02Nitrogen oxides 2.96 E+05NMVOC (unspecified) 2.65 E+04

Acidifcation Potential(a) 1.49 E+05Eutrophication Potential(b) 3.84 E+04Photochem. Ozone Creation Potential(c) 2.97 E+05(a) (Nitrous oxides * 0.5) + (Sulphur dioxide * 1)(b) (Nitrous oxides * 0.13)(c) (Nitrous oxides * 1) + (NMVOC * 0.048) + (Sulphur dioxide *

0.028)

Table C.6: Bemax Resources Limited Facilities 2009 [33]Facility LocationBroken Hills Mineral Separation Plant Broken Hills, NSWGinko Mineral Sands Operations Pooncarie, NSWGwindinup Operations Gwindinup, WANorth Shore Operations Bunbury, WASandlewood Mine Benger, WASnapper Mine Pooncarie, NSWTutunup Operations Tutunup, WA

Table C.7: Exxaro Production 2009 [57]Substance Production [tonnes]Chloride slag 201000Ilmenite 612000Pig iron 181000Rutile 46000Scrap iron 15000Sulphate slag 44000Zircon 164000

Zircon share(a) 39.5%(a) Zircon value of total production, calcu-

lated using prices from Table C.18, assum-

ing scrap iron is priced as ferrous scrap

and assuming chloride and sulphate slag

is priced as titaniferrous slag

Table C.8: Exxaro Emissions and Resource Consumption 2009 [57]Substance Amount UnitCO2 1206.5 KtEnergy 5007.3 TJWater 13029937 M3

77

Table C.9: Iluka Resources Limited Emissions 2009 [33]Substance Emissions [kg]Ammonia 1.51 E+04Nitrogen oxides 2.50 E+06NMVOC (unspecified) 2.02 E+05Particulate matter 5.12 E+06Sulphur dioxide 7.78 E+04

Acidifcation Potential(a) 1.35 E+06Eutrophication Potential(b) 3.30 E+05Photochem. Ozone Creation Potential(c) 2.76 E+05(a) (Ammonia * 1.6) + (Nitrous oxides * 0.5) + (Sulphur dioxide * 1)(b) (Ammonia * 0.33) + (Nitrous oxides * 0.13)(c) (Nitrous oxides * 1) + (NMVOC * 0.048) + (Sulphur dioxide *

0.028)

Table C.10: Iluka Resources Limited Production 2009 [58]Substance Production [tonnes]Ilmenite (saleable) 342100Ilmeinte (upgradable) 496700Rutile 141400Zircon 263100

Zircon share(a) 63.1%(a) Zircon value of total production, calculated using

prices from Table C.18, assuming same price for sal-

able and upgradable ilmenite

Table C.11: Iluka Resources Limited Facilities 2009 [33]Facility LocationBunbury Wharf Bunbury, WACapel Capel, WADouglas Mineral Sands Mine Douglas, VICEneabba East Eneabba, WAGeraldton Wharf Geraldton, WAGingin Mine Site Gingin, WAHamilton Mineral Separation Plant Hamilton, VICJacinth Ambrosia Mine Site Nullarbor, SAKulwin Mineral Sands Mine Ouyen, VICNargulu Narngulu, WAWagerup Mine Waroona, WAWaroona Mine Site Waroona, WAYoganup West Capel, WA

78

Table C.12: Iluka Resources Limited Emissions and Resource Consumption 2009[58]

Substance Amount UnitCO2 1078 KtEnergy 10945 TJWater 36478 M liters

Table C.13: Tiwest Emissions 2009 [33]Substance Emissions [kg]Ammonia 1.18 E+05Nitrogen oxides 3.83 E+05NMVOC (unspecified) 3.23 E+04Particulate matter 3.00 E+06Sulphur dioxide 1.14 E+06

Acidifcation Potential(a) 1.52 E+06Eutrophication Potential(b) 8.87 E+04Photochem. Ozone Creation Potential(c) 4.16 E+05(a) (Ammonia * 1.6) + (Nitrous oxides * 0.5) + (Sulphur dioxide * 1)(b) (Ammonia * 0.33) + (Nitrous oxides * 0.13)(c) (Nitrous oxides * 1) + (NMVOC * 0.048) + (Sulphur dioxide *

0.028)

Table C.14: Tiwest Production 2009 [57]Substance Production [tonnes]Ilmenite 414000Leucoxene 28000Rutile 32000Zircon 66000

Zircon share(a) 54.3%(a) Zircon value of total production, calcu-

lated using prices from Table C.18, assum-

ing leucoxene is priced as ilmenite

Table C.15: Tiwest Facilities 2009 [33]Facility LocationBunbury Port Authority Vittoria, WAChandala Muchea, WACooljarloo Cataby, WA

79

Table C.16: Kenmare Resources Production 2009 [59]Substance Production [tonnes]Ilmenite 471500Rutile 1800Zircon 21100

Zircon share(a) 34.7%(a) Zircon value of total production, calcu-

lated using prices from Table C.18

Table C.17: Kenmare Resources Emissions and Resource Consumption 2009[59]

Substance Amount UnitCO2 76228 tonnesElectricity 82724 kWhWater 3840 M liters

Table C.18: USGS Mineral Prices 2009 [55]Substance Price [USD/tonne]Ilmenite, F.O.B. Australian port 73Ferrous scrap, import 237Pig iron, all grades import 262Rutile, bulk F.O.B. Australian port 533Titaniferrous slag, import, 80% to 95% TiO2 420Synthetic Rutile, US Import 318Zircon, Australia 890

80