MINING AND EXPLORATIONRELATED NORM IN FINLAND

Heini Reijonen, GTK, heini.reijonen@gtk.fi

27.9.2019

1

Seminar on SURFACE Near Surface Repositories in Finland. GTK auditorium , Vuorimiehentie 7, 02150 Espoo. 26.9.2019

27.9.2019

2

CONTENTS

• Introduction

• Status of mining

• Ongoing projects

• Exploration and resources

27.9.2019

3

INTRODUCTION – SOME BACKGROUNDThe average uranium and thorium concentrations of Finnish bedrock are 2.0 ppm and 8.9 ppm, respectively [1]

[1] LAURI, L., POHJOLAINEN, E., ÄIKÄS, O., Selvitys Suomen kallioperän U-pitoisuudesta, Geological Survey of Finland, Archive

Report M10/2010/53 (2010) (in Finnish).

27.9.2019

4

INTRODUCTION - NORM FROM MINING

Many mineral resources are of relatively low grade, or have complex, polymetallic assemblages, in which gold, base metals, phosphates and rare earth elements (REE) may also be associated with NORM; the latter association reflects the fact that REE, uranium, and thorium exhibit similar geochemical behaviour in rock-forming magmatic processes

Mining and mineral processing of NORM bearing ores can lead to elevated concentrations of uranium and thorium, and their progeny (e.g. 226Ra, 222Rn, 210Pb, 210Po) in minewater, tailings, waste rock and mineral dust, resulting in potential radiation and chemical risks.

Data presented here is an update of IAEA 2016 [2][2] IAEA 2016. Naturally occurring radioactive material (NORM VIII). Proceedings of and international symposium, Rio de Janeiro, Brazil, 18-21 October, 2016.

STATUS OF MINING

27.9.2019

5

• Many mineral resources have complex, polymetallic assemblages, in which gold, base metals, rare earth elements (REE), niobium or phosphates are associated with natural radionuclides

• Several projects ongoing related to polymetallic ores/deposits

There is no primary uraniummining in Finland

today

ONGOING PROJECTS

27.9.2019

6

• Talvivaara: nickel mine in Sotkamo

• Juomasuo and Hangaslampi: gold deposits in the Kuusamo region

• Sokli phosphate mine project in eastern Lapland

• Katajakangas Nb–rare earths deposit in the Otanmäki area

• Rompas gold–uranium prospect in Ylitornio

27.9.2019

7

U/Th contents in various deposits

TALVIVAARA:• Nickel–zinc–copper–cobalt deposit: 17 ppm U in the ore, the activity concentrations of U-

238 from 58 Bq/kg to 3375 Bq/kg in the gypsum pond wastes

JUOMASUO & HANGASLAMPI:• Gold–cobalt (two deposits): 158 ppm U on average at Juomasuo and 194–347 ppm U at

Hangaslampi

ROMPAS:• Gold deposit: Up to tens of wt% U

KATAJAKANGAS:• Niobium–rare earths deposit: Hundreds of ppm U and Th

OVERVIEW OF SOMEONGOING PROJECTS

27.9.2019

8

TALVIVAARA

27.9.2019

9

Ni-Zn-Cu-Co deposit

In 2010, Talvivaara SotkamoOy announced plans to

recover uranium as a by-product using solvent

extraction, resulting from the fact that a large part of

uranium dissolves in the process solution (PLS) during heap leaching

Image: IAEA

• Part of the uranium ends up in the gypsum pond wastes and minor part in the Ni–Co sulphide concentrate product Uranium residuals have been extracted from the Ni–Co concentrate at Harjavalta, and reported to the Radiation and Nuclear Safety Authority (STUK)

TALVIVAARA

27.9.2019

10

Attribution 2.0 Generic (CC BY 2.0) -Antti Lankinen

27.9.2019

11

RADIONUCLIDES IN THE PROCESS

The uranium concentration of the gypsum pond wastes is highly variable (6–260 ppm U), being about 100 ppm U on average

The activity concentrations of U-238 in the gypsum pond wastes range between 58 Bq/kg and 3375 Bq/kg, the latter exceeding the 1000 Bq/kg level• international radiation protection standards, the material would be regarded as radioactive for purposes of radiation protection

The main secondary minerals in the heaps are jarosite [KFe3+3(OH)6(SO4)2], goethite [FeO(OH)] and

gypsum [CaSO4 ·2H20]

Uranium progeny (Ra-226, Pb-210 and Po-210) mostly remain in the heaps during the leaching process (associated with secondary sulphate minerals)

Thorium and progeny (Th-232, Th-228, Ra-228) are also mainly retained in the heaps

In October 2017, Terrafame Oy applied to the Finnish government for a licence to recover uranium as a by-product at Terrafame’s mine in Sotkamo, in accordance with the nuclear energy legislation

ROMPAS

27.9.2019

12

Gold occurs mostly in association withuraninite [UO2]

This prospect is rich in uranium,

but very rich in gold, which is the main

target metal

ROMPAS-RAJAPALOT PROJECT

27.9.2019

13

• Exploration by Mawson

Images: Mawson

27.9.2019

14

DETAILS…

Rompas-type hydrothermal gold vein discovery over a 6 km strike length, with a width of 200–250 m

Mostly hosted by carbonate and calc-silicate veins in mafic metavolcanic rocks

Gold is intimately associated with uraninite, typically in microfracturesof uraninite

SOKLI

27.9.2019

15

• Sokli phosphate deposit is hosted by the Devonian Sokli carbonatite complex (365 Ma)

• The Sokli ore is hosted by the surface weathered zone (regolith) of the carbonatite, with the ore mainly consisting of apatite [Ca5(PO4)3(F,Cl,OH)]

• Most uranium is bound to pyrochlore group minerals [(Na,Ca)2Nb2O6(OH,F)] in the regolith

• Thorium is mostly incorporated in pyrochloregroup and monazite group (Ce,La)PO4 minerals(e.g. Ce, La, Nd, Th and Sm bearing variants)

Uraniferousphosphorus deposit in

eastern Lapland

There are currently no plans by Yara for

recovering uranium as a by-product

SOKLI

27.9.2019

16

• During regolith formation, uranium was partially dissolved from pyrochlore due to weathering processes, and then fixed to some degree in secondary apatite within the regolithic phosphate

• In addition to the association with secondary apatite, uranium is also present to a lesser degree in fine grained goethite and altered residual magnetite [Fe3O4] within the regolith

Source: After O’Brien et al. (2005).

KUUSAMO

27.9.2019

17

Several uraniferouspolymetallic Au-Co-U

deposits in the KuusamoSchist Belt, eastern

Finland, such as Juomasuo, Hangaslampi,

Pohjasvaara, Meurastuksenaho and

Sivakkaharju

JUOMASUO

27.9.2019

18

Uraninite is found together with gold in fracture fillings and shear seams, and is erratically distributed throughout the gold lodes and sometimes within the cobalt mineralized zone

Uraninite and gold

grains in drill

core of Juomasuo.

Figure:

Dragon Mining Ltd.

KATAJAKANGAS

27.9.2019

19

• Rare metal (Nb, REE, Zr, Ta) deposit

• Minerals are confined to narrow, fine grained, silicified zones 0.2–1.4 m thick, hosted by Paleoproterozoic gneissic granite

• These mineralized zones have several hundred parts per million U and Th

• Fergusonite [(Y,REE)NbO4] is the dominant host to uranium, and allanite[A2M3Si3O12[OH], A sites can host largecations] to thorium

Katajakangas deposit has never been developed for mining, but an exploration

licence covering the Katajakangas area is currently held by the

private company OtanmäkiMine Oy

27.9.2019

20

OTHER PROSPECTS WITH U/Th

• Mining register map service

• 56 deposits (purple circles) withreported U as commodity

• No claims, explorations permits at themoment with U as main commodity

• There is currently no uranium exploration in Finland

• However, uranium is included as a mining mineral in some exploration permits and exploration permit applications of Mawson Resources Ltd

27.9.2019

21

U RESOURCES

• Finland reports a total of 1 500 tU of reasonably assured conventional resources in the Palmottu and Pahtavuoma U deposits

• Unconventional resources of uranium in the Talvivaara black schist-hosted Ni-Zn-Cu-Co deposit are approximately 16 000 tU in the measured and indicated resources of 970 Mt, and about 24 000 tU in the total mineral resources (measured, indicated and inferred) of 1 458 Mt, calculated from the resource update 2016 by Terrafame Oy

27.9.2019

22

SUMMARY

The presence of NORM depends on the deposit type and miningprocess

Mineralogy varies between deposit types, assessment case-by-case

Detailed mineralogical characterization of the deposits is essential for understanding the deportment of radionuclides during mining and mineral processing, in order to both optimize metal recovery and ensure compliance with environmental guidelines

KIITOSheini.reijonen@gtk.fi

www.gtk.fi