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With the support of KFPE Commission for Research Partnershipswith Developing Countries

ASSESSMENT OF GOLD RECOVERY PROCESSES

IN BANGALORE,INDIAAND EVALUATION OF ANALTERNATIVE RECYCLING PATH

FOR PRINTED WIRING BOARDS

A CASE STUDY

Diploma thesis at the Institute for Spatial and Landscape Planning, Regional Resource

Management at the ETH Zurich

October 2006

Diploma Student: Miriam Keller

Supervisors: Prof. Dr. Susanne Kytzia (ETH) and Rolf Widmer (EMPA)

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Abstract

i

Abstract

Recycling of e-waste respectively of PWB is an ambiguous issue. On the one hand,

precious metals can be recovered; on the other hand, environmental damages are caused

during the recycling processes. The encountered recycling management system inBangalore bears several problematic processes. One of the identified problematic

processes by Rochat (2006) is the precious metal recovery. For example to recover gold

from e-waste wet chemical leaching processes, which use several hazardous substances

and materials (e.g. cyanide and nitric acid) are conducted. Scientific base data about these

processes are barely available. Therefore, the focus of this thesis is to provide scientific

background knowledge about gold recovery processes. In addition, an alternative pathway

for the recycling of e-waste-, respectively of printed wiring boards (PWB) is evaluated.

Using the methodology of material flow analysis (MFA) the used substances and materials

of three different gold recovery techniques could be identified and partly quantified. Based

on these results environmental impacts of the processes are qualitatively evaluated. The

environmental contamination caused by the conducted processes in Bangalore is severe.

The released toxic substances and heavy metals are high concentrated and most of them

have the potential to accumulate in organisms and environment. In the effluent of a

conducted gold recovery technique in an informal facility in Bangalore, metal concentrations,

which are 5 to 370 times higher than the maximum permissible value in Switzerland, were

detected. The solid waste from the processes, end up in the solid waste stream of

Bangalore. This means that the metals eventually leach out to the environment.

Further, the efficiency of the PWB recycling processes in Bangalore could be determined

making a substance flow analysis (SFA) of gold. This assessment revealed that the gold

yields of the recycling systems are quite poor. The yields of the gold recovery techniques

are approximately 50 %.

The assessed alternative is a relocation of the PWB treatment to an industrial smelter in

Belgium (Umicore Precious Metals Refining) which is equipped with best available

technology. It could be shown that the economic profit is much higher if the material is sold

to the industrial smelter. In addition, the emissions to the environment would decrease

drastically if these fractions of e-waste were treated with the metallurgic technique,

conducted in Belgium.

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Acknowledgement

ii

Acknowledgement

I would like to express my gratitude to all those who gave me the possibility to complete this

thesis. Special thanks belong to

David Rochat, who accompanied my fieldwork in India being a mentor and a friend.

the whole staff of the GTZ-office in Bangalore where I had a working place and met

wonderful people.

Mr. Parthasarathy and his employees, especially Mr. Prakashchandra, whose help were

essential to realise this work.

Rizwan Khan and his workers for their cooperation.

Umicore Precious Metals Refining who offered to make the analysis and in particular

Steven Art and Jan Kegels for providing all the essential information and

Dr. Eddie Adriaenssens, Dr. Christian Hagelken and Thierry van Kerckhoven for the

several advices.

Rolf Widmer, the e-waste expert of EMPA and Professor Susanne Kytzia for supervising

and guiding me during this thesis.

Martin Streicher-Porte for providing a lot of information and giving critical and constructive

comments to my work.

Dr. Hartmut Schnberg, Dr. Richard Klinger, Dr. Johannes Gauglhofer, Mischa Classen

and Dr. Christina Seyler-Jahn for the fruitful discussions and information.

Dominik Zumbhl and Ronny Haase for their company and the highly appreciated

sharing of IT knowledge.

Lucia Oetjen, Reto Keller and Dr. Oskar Keller for reviewing my thesis.

my parents for giving me constant support and encouragement throughout all the years

of my studies.

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Table of contents

iii

Table of contents

Abstract .................................................................................................................................. iAcknowledgement ................................................................................................................ ii 1 Introduction ................................................................................................................11.1 What is e-waste? .........................................................................................................11.2 Global e-waste situation...............................................................................................2

1.2.1 Global e-waste development............................................................................21.2.2 E-waste management and regulation...............................................................4

1.3 E-waste Situation in India ............................................................................................61.4 E-waste Situation in Bangalore....................................................................................71.5 Scope and aims of the thesis.......................................................................................9

1.5.1 Scope ...............................................................................................................91.5.2 Aims and scientific questions ...........................................................................9

1.6 Proceeding and structure of thesis ............................................................................ 102 Gold recovery techniques and hazards.................................................................112.1 Methodology .............................................................................................................. 112.2 System Description....................................................................................................12

2.2.1 System definition............................................................................................122.2.2 Data collection................................................................................................132.2.3 Investigated facilities ......................................................................................132.2.4 Cyanide leaching at Eco BIRD.......................................................................152.2.5 Mercury amalgamation at Eco BIRD..............................................................202.2.6 Gold stripping at Surface Chem Finishers......................................................22

2.3 Quantification.............................................................................................................24 2.3.1 Data collection................................................................................................242.3.2 Cyanide leaching at Eco BIRD.......................................................................252.3.3 Mercury amalgamation at Eco BIRD..............................................................282.3.4 Gold stripping at Surface Chem Finishers......................................................29

2.4 Interpretation..............................................................................................................30 2.4.1 Cyanide leaching at Eco BIRD.......................................................................302.4.2 Mercury amalgamation at Eco BIRD..............................................................322.4.3 Gold stripping at Surface Chem Finishers......................................................33

2.5 Discussion..................................................................................................................34 2.5.1 Suitability of the method.................................................................................342.5.2 Evaluation of the systems ..............................................................................34

3 Evaluation of recovery rates ...................................................................................393.1 Methodology .............................................................................................................. 39

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iv

3.2 System description.................................................................................................... 393.2.1 System definition ........................................................................................... 393.2.2 Investigated systems ..................................................................................... 40

3.3 Quantification ............................................................................................................ 403.3.1 Preparation .................................................................................................... 403.3.2 Subsystem 1 .................................................................................................. 413.3.3 Subsystem 2 .................................................................................................. 44

3.4 Interpretation ............................................................................................................. 483.4.1 Informal sector ............................................................................................... 493.4.2 Formal sector................................................................................................. 49

3.5 Discussion................................................................................................................. 493.5.1 Informal sector ............................................................................................... 503.5.2 Formal sector................................................................................................. 50

4 Comparison of two PWB recycl ing scenarios ...................................................... 524.1 Scenario description.................................................................................................. 52

4.1.1 Scenario A ..................................................................................................... 524.1.2 Scenario B ..................................................................................................... 52

4.2 Methodology.............................................................................................................. 524.3 Environmental assessment ....................................................................................... 53

4.3.1 Goal and scope definition .............................................................................. 534.3.2 Inventory analysis.......................................................................................... 544.3.3 Interpretation.................................................................................................. 57

4.4 Economic assessment .............................................................................................. 594.4.1 Goal and scope definition .............................................................................. 594.4.2 Inventory analysis.......................................................................................... 594.4.3 Impact assessment........................................................................................ 614.4.4 Interpretation.................................................................................................. 62

5 Conclusion ............................................................................................................... 645.1 Main findings ............................................................................................................. 64

5.1.1 Gold recovery techniques and hazards ......................................................... 645.1.2 Evaluation of recovery rates .......................................................................... 645.1.3 Comparison of two PWB recycling scenarios................................................ 65

5.2 Outlook...................................................................................................................... 66References .......................................................................................................................... 68

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Table of contents

v

Appendices ..........................................................................................................................72Appendix I: Glossary...........................................................................................72

Appendix II: Secos global e-waste programme................................................... 74

Appendix III: E-waste definitions...........................................................................75

Appendix IV: Environmental legislations in India................................................... 76

Appendix V: The E-waste Agency (EWA) ............................................................ 77

Appendix VI: Development of gold price between 1993 and 2006........................ 78

Appendix VII: Material and sample preparation ..................................................... 79

Appendix VIII: Flowchart material preparation ........................................................ 88

Appendix IX: Detailed flowchart mercury amalgamation ....................................89

Appendix X: Pictures documenting the mercury amalgamation ........................ 90

Appendix XI: Silver recovery ................................................................................. 92

Appendix XII: Detailed flowchart Gold stripping................................................... 93

Appendix XIII: Indicative assay results on e-scrap samples - 21/8/06 .................... 94

Appendix XIV: Assay results from liquid samples.................................................... 95

Appendix XV: Summary of hazardous substances and metals .............................. 97

Appendix XVI: Anhang 3.2, Gewsserschutzverordnung (GSchV) 814.201......... 101

Appendix XVII: Indicative Purchase Prices from UPMR.........................................102

Appendix XVIII: Used ecoinvent data ......................................................................103

Appendix XIX: Umicore Precious Metals Refining (UPMR)................................... 104

Appendix XX: Approximate theoretical value of the basic raw material (BRM) ....105

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List of Figures

vi

List of Figures

Figure 1.1: Top scoring countries in PC growth rates (left) and penetration rates (right)(Schwarzer et al., 2005)......................................................................................3

Figure 1.2: PC market trends in India from 1997 to 2004 (BIRD, 2005)...............................7Figure 1.3: Simplified process sheet of the present Bangalore e-waste managementsystem. Problematic processes are indicated by a flash; unknown or unclear

processes are indicated with a question mark (Rochat, 2006)...........................8Figure 2.1: MFA system definition; the system boundary is indicated with dashed lines;

squares represent processes, ovals substances, materials, solutions andmixtures.............................................................................................................12

Figure 2.2: Simplified flowchart of the cyanide leaching...................................................19Figure 2.3: Simplified flowchart of the mercury amalgamation........................................22Figure 2.4: Simplified flowchart of the gold stripping. .......................................................24Figure 2.5: Quantified flowchart of the cyanide leaching (main process); unit of numbers is

gram..................................................................................................................26

Figure 2.6: Preparation of silver-salt used in the main process of the cyanide leaching; unitof numbers is gram. ..........................................................................................27

Figure 2.7: Simplified and quantified flowchart of the gold stripping; unit of numbers isgram..................................................................................................................29

Figure 2.8: Major flows of the cyanide leaching. ..............................................................35Figure 2.9: Major flows of the mercury amalgamation......................................................37Figure 2.10: Major flows of the gold stripping. ....................................................................37Figure 3.1: SFA system definition; the system boundaries are indicated with dashed lines;

squares represent processes, ovals materials, solutions and mixtures where

the gold is contained.........................................................................................40Figure 3.2: Mass flow of the material during preparation; BRM= Basic raw material, IM=

Input material. ...................................................................................................41Figure 3.3: Scheme for the calculation of the input material (Subsystem 1). .....................42Figure 3.4: Conducted dismantling for the informal sector; BRM =Basic raw material, IM =

Input material, C and B = material, the denominations accord with AppendixVIII.....................................................................................................................42

Figure 3.5: Approximate gold flow in the Subsystem 1 (informal sector)............................43Figure 3.6: Conducted dismantling for the formal sector; BRM =Basic raw material, IM =

Input material, A = material, the denominations accord with Appendix VIII. ....43Figure 3.7: Approximate gold flow in the Subsystem 1 (formal sector). .............................44Figure 3.8: Scheme for the calculation of the input material (Subsystem 2). .....................45Figure 3.9: Conducted gold recovery in the informal sector; IM = Input material, BC = Body

components, WS = Waste solution, SS = Silver solution, Au = Gold. ..............45Figure 3.10: Approximate gold flow in the Subsystem 2 (informal sector)............................46Figure 3.11: Conducted gold recovery in the formal sector; IM = Input material, BC = Body

components, L = Liquid after Leaching.............................................................47Figure 3.12: Approximate gold flow in the Subsystem 2 (formal sector). .............................47Figure 3.13: Illustration of the gold yields..............................................................................48Figure 4.1: Scheme of life cycle assessment (LCA) comprising four steps (Guine et al.,2001).................................................................................................................53

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List of Figures

vii

Figure 4.2: System definition of the environmental assessment; the system boundaries areindicated with dashed lines; the squares represent processes, ovals materials;PWB= Printed wiring boards, IM= Input material, UPMR= Umicore PreciousMetals Refining. ................................................................................................54

Figure 4.3: Emissions of the scenarios per ton board.........................................................56Figure 4.4: Raw material depletion of the scenarios per ton board. ...................................57Figure 4.5: PWB recycling system and system boundary of the environmental assessment;

squares represent processes and actors, ovals materials; the system boundaryof the analysed system is indicated with dashed lines; PWB= Printed wiringboards, IM= Input material................................................................................59

Figure 4.6: Money flux (in EUR) in Scenario A. ..................................................................61Figure 4.7: Money flux (in EUR) in Scenario B. ..................................................................61Figure 5.1: Major flows of the cyanide leaching..................................................................64Figure 5.2: Gold yields in the informal and formal sector of PWB recycling in Bangalore;

BRM= Basic raw material (printed wiring boards), IM= Input material (apparentgold parts).........................................................................................................65

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List of Tables

viii

List o f Tables

Table 2.1: Input materials of the cyanide leaching per gram recovered gold.......................27Table 2.2: Output materials of the cyanide leaching per gram recovered gold....................27Table 2.3: Input materials of the mercury amalgamation per gram recovered gold.............28Table 2.4: Output materials of the mercury amalgamation per gram recovered gold..........28

Table 2.5: Input materials of the gold stripping per gram recovered gold..........................30Table 2.6: Output materials of the gold stripping per gram recovered gold.......................30Table 2.7: Metal concentrations in the waste solution of the cyanide leaching.................31Table 2.8: Metal concentration in the body components of the cyanide leaching .............31Table 2.9: Comparing the thresholds of the Swiss legislation (see Appendix XVI) of

industrial waste water with the found concentration in the waste solution of thecyanide leaching ...............................................................................................32

Table 2.10: Metal concentration in the body components of the gold stripping...................34Table 3.1: Overview of the calculation of the gold in the input material 1 (Subsystem 1)....43Table 3.2: Overview of the calculation for the input material 2 (Subsystem 1) ....................44Table 3.3: Overview for the calculation of the gold in the input material 1 (Subsystem 2) ..46Table 3.4: Overview of the calculation for the input material 2 (Subsystem 2) ....................47Table 3.5: Gold yields of Eco BIRD (cyanide leaching)........................................................49Table 3.6: Gold yields of Surface Chem Finishers (gold stripping)......................................49Table 4.1: Inventory of environmental indicators; functional unit: one ton PWB..................56Table 4.2: Emissions to air during shipping (Scenario B).....................................................56Table 4.3: Approximate theoretical value of input material 1 (IM 1).....................................60Table 4.4: Approximate evaluation of total expenses (Scenario A) .....................................61Table 4.5: Economical benefit of the scenarios in / t IM 1.................................................61

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Chapter 1 Introduction

1

1 Introduction

The in hand thesis is embedded in secos (Swiss State Secretariat for Economic Affairs)

global e-waste programme Knowledge Partnerships in e-Waste Recycling (see Appendix

II). This programme is carried out by EMPA (Swiss Federal Laboratories for MaterialsTesting) with the main objective to improve existing e-waste management systems and is

conducted in three different countries: China, South Africa and India. The evaluations of

gold recovery techniques using e-waste (printed wiring boards) as input material, conducted

for this thesis, took place in India. A collateral diploma thesis focuses on different strategies

to recycle CRT (cathode ray tube) recycling in South Africa (Zumbhl, 2006).

E-waste is thus a globally treated issue. The meaning of e-waste is discussed in the next

chapter. In the following chapters, the global relevance of e-waste is explained. Further the

e-waste situation in India is described which leads to the scope and aims of this thesis.

1.1 What is e-waste?

In common speech in an industrialised country e-waste can be regarded being an

electrical or electronic device which has no further (economic) value to its owner. However

when an electrical or electronic device becomes useless for the current owner it can still

have a value for the next holders. The owner can sell it and then it follows a chain where it is

reused, recovered or finally disposed of. Consequently, e-waste is a very difficult term to

define. Today there is no generally accepted definition for the term e-waste (Widmer et al.,

2005). Attempts to define the term have been performed by several authorities and authors.

A selection of definitions and the different categories defined by the EU WEEE Directive

(EU, 2003a) are listed in Appendix III. In this study e-waste is referred to as "Any appliance

using an electric power supply that has reached its end-of-life as it is defined by the

Organisation for Economic Co-operation and Development OECD (2001). E-waste is a

controversial issue discussed on a global scale and features several risks and opportunities.

One opportunity of e-waste is that the appropriate recycling is clearly advantageous froman environmental perspective. as proved in a study conducted by Hischier, et al. (2005).

The authors compared the environmental impacts of a scenario of e-waste recycling to the

baseline scenario of incineration of all e-waste and primary production of raw materials.

Another prospect of e-waste is its content of valuable raw materials (also strategic

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2

materials1) including many rare metals. They can be recovered with different existing

techniques. Thus, e-waste recycling has become a lucrative business.

The risky part of e-waste is that it contains over 1000 different substances and metals.

Many of these substances and metals are toxic. According to Widmer et al. (2005) hazards

such as lead, mercury, arsenic, cadmium, selenium, hexavalent chromium and flame

retardants in casings and circuit boards are present. The printed circuit boards (i.e. printed

wiring boards) contain polychlorinated and polybrominated biphenyls that create dioxin-like

emissions when burned. All these hazardous substances can threaten human health and

the environment unless they are disposed of properly (Li et al., 2006). Corresponding to

Silicon Valley Toxics Coalition (Puckett et al., 2002) About 70 % of heavy metals (including

mercury and cadmium) found in landfills come from electronic discards. According to a

report of the European commission 40 % of the lead found in landfills derives fromconsumer electronics (Commission of the European Communities, 2000).

Thus, e-waste is a double-edged sword. On the one hand, valuable materials can be

recovered economically whilst natural resources can be saved. On the other hand, the risks

of hazardous substances when not recycled properly and released to the environment can

cause serious damage to human health and the environment.

1.2 Global e-waste situation

1.2.1 Global e-waste development

Because of the rapid technological progress and the decreasing lifespan of the single

electronic devices, e-waste is growing rapidly. In 2004, more than 180 million personal

computers (PCs) were sold worldwide. In the same year, an estimated 100 million obsolete

PCs entered waste streams (Widmer et al., 2005). Worldwide e-waste growth can only be

estimated and is in the range of 20 to 50 million tons per year. The main volume is produced

in North America followed from Europe and Asia (Siemers and Vest, 1999). According to

The Economist (2005) e-waste is one of the fastest growing waste fractions. It accounts for

around 8 % of all municipal waste in industrialised countries.

At present e-waste is mainly generated by industrialised countries, which already have a

high amount of electrical and electronic equipment. It is assumed that some of the e-waste

generated in these countries ends up in developing countries such as India or Africa. The

British Protection Agency released a report in May 2005 admitting that a large amount of e-

1

Material for which the quantity required for essential civilian and military uses exceeds thereasonably secure domestic and foreign supplies and for which acceptable substitutes are notavailable within a reasonable period of time (American Metal Market, 1985)

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3

waste had been exported illegally from the UK (Agarwal, 2005). In Lagos (Nigeria) 400000

used computers arrive at the port each month. 25 % 75 % of them are out of order and

have to be disposed of (Puckett et al., 2002). According to Iles (2004) the US exported up to

10.2 millions obsolete computers to Asia in 2002, which makes around 50 % 80 % of all

PCs sent for recycling in the US. The reason for these exports might be the less strict

environmental standards in developing countries and the lower costs for disposal. For

example disposing a computer in the US can cost up to USD 20. The same device sold to

an Indian e-waste trader would yield USD 10 and USD 15 (Agarwal, 2005).

In the future however, the developing countries themselves will produce a large quantity of

e-waste. Figure 1.1 shows the growth of personal computers in the different countries. It

reveals the enormous PC growth per capita in developing countries.

Due to the above developments, countries like India, China and Africa will face anincreasing amount of e-waste in the coming years, originating through illegal exports and

from inland. To deal with the fast-growing, valuable and hazardous waste load, this waste

stream has to be managed properly and has to be controlled by putting up guidelines and

regulations.

Figure 1.1: Top scoring countries in PC growth rates (left) and penetration rates (right) (Schwarzeret al., 2005).

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4

1.2.2 E-waste management and regulation

1.2.2.1 E-waste management

The idea of an e-waste management is to set up a local or nationwide system where e-

waste finds the way back within the country of origin from the consumer to a recycling facility

rather than to the municipal solid waste stream or to the landfill. Several organisations, i.e.

the Secretariat of Basel convention or the StEP-initiative try to develop global standards

of such management systems. A central goal of the Basel convention is environmentally

sound management (ESM). ESM means taking all practical steps to minimise the

generation of hazardous wastes and strictly controlling its storage, transport, treatment,

reuse, recycling, recovery and final disposal, the purpose of which is to protect human

health and the environment. (Secretariat of the Basel Convention, 2006). One of the five

major tasks of StEP is to enhance infrastructures, systems and technologies to realisesustainable e-waste recycling (StEP, 2005). Different possibilities to finance recycling are

available, for instance introducing an Advanced Recycling Fee (ARF) or a payment at the

time of the disposal.

In Switzerland, a properly functioning e-waste management has been realised. It is the first

country who has established a nation-wide take-back system with state of the art recycling

technologies, financed by an ARF. This system was established in the early 90s based on

the initiative of the electronic industry itself. The current system is now controlled by two

producer responsibility organisations (P.R.O): SWICO Recycling Guarantee and SENS.

SWICO comprises more than 400 providers in the ICT/CE segment and has become one of

the most important industry associations in Switzerland.

Even if a country or region organises its e-waste management system within the industry,

legislations have to be set up to define the general framework. From the economical point of

view the valuable parts of e-waste, for example precious metals are from particular interest.

Therefore, these parts will be recovered, steered by the market demand. To prevent that

recyclers take only these parts (cherry-picking) and dump the invaluable and often toxicparts, regulations have to be implemented. Legislations therefore generally focus on the

decontamination of e-waste.

1.2.2.2 European e-waste legislation

In 2003 the European Community introduced the WEEE (Waste Electrical or Electronic

Equipment) Directive 2002/96/EC (EU, 2003a). This regulation is currently being transposed

in the EU member states. Main objectives and regulations are the prevention, reuse and

recycling of e-waste and to reduce the disposal of e-waste as unsorted municipal waste.

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5

Most of the costs for the current disposal and the environmental sound recycling of e-waste

are generated due to its hazardous substances. To reduce the hazardous content of future

e-waste the RoHS (Restrictions of Hazardous Substances) directive (EU, 2003b) bans

several hazardous substances in the manufacturing of EEE. Materials like lead, mercury or

polybrominated biphenyls (PBB) have to be substituted by safer materials if technically and

economically feasible. The appendix of the RoHS directive specifies some exceptions for

the use of mercury mainly in fluorescent lamps, lead in CRTs or solder, cadmium and

hexavalent chromium and lead containing devices are defined. The regulation has become

effective by July 2006.

1.2.2.3 Intercontinental legislation

Despite of the implementation of the above-mentioned legislations there are still concerns

about the treatment of e-waste in non EC- or OECD countries. As mentioned before thedriving forces for the recyclers to send e-waste to developing regions are low labour costs

and partly the absence of environmental regulations. This makes it economically interesting

to send e-waste to non OECD-countries such as China and India.

To prevent the developed world to use the developing world as a dumping ground a

multilateral environmental agreement known as the Basel Convention (BC) was

implemented and entered into force in 1992. BC is an UN convention and its principle idea

was to set up a framework for controlling the transboundary movements of hazardous

wastes. In 1995, the Ban Amendment which is incorporated in the BC had been

introduced. The Amendment calls for prohibiting exports of hazardous wastes (for any

purpose) from countries listed in a proposed new annex to the Convention (Annex VII -

Parties that are members of the EU, OECD, Liechtenstein) to all other Parties to the

Convention. The Amendment has not yet entered into force (Secretariat of the Basel

Convention, 2006).

The implementation of the BC and related agreements are coordinated by the Secretariat of

the Basel Convention, located in Geneva, Switzerland and administered by UNEP. It alsoprovides assistance and guidelines on legal and technical issues, gathers statistical data

and conducts training on the proper management of hazardous waste (Secretariat of the

Basel Convention, 2006).

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1.3 E-waste Situation in India

At present, the e-waste management system in India is characterised by a market driven

collection and recycling implying no direct cost to consumers, producers or taxpayers. The

system is dominated by the informal sector in backyard workshops (Sinha-Khetriwal et al.,2005). Backyard workshops are considered being a part of the informal economy. Informal

and underground economy is defined by Frey and Schneider (2000): It comprises all

presently not recorded productive (i.e. value-adding) activities which should be in the

national product (GNP). In this thesis the informal scrap industry is seen as recycling

facilities that do not comply with state regulations regarding taxation, environmental

protection or safety standards (Streicher-Porte, 2006).

Up to now no regulations or controls on material or financial flows, standards of emissions or

occupational hazards have been implemented (Sinha, 2004). Though India signed the Basel

Convention, there is no specific legislation regulating the export or the collection and

treatment of e-waste. There are however several existing environmental legislations which

are of importance and useful in the context of e-waste (see Appendix IV).

India is one of the countries that have to deal with the arising load of e-waste. Figure 1.1

indicates that the PC growth per capita in India had been over 1000 % between 1993 and

2000. From 2002 to 2004 the sales of computers in India almost doubled as a market study

shows, which had been performed in 22 Indian cities (see Figure 1.2). Since the growth ofPC sales correlates with the generation of e-waste (Jain and Sareen, 2006) these sales

implicate a massive increase of e-waste.

As an outcome of Phase I of secos global e-waste programme the Indo-German-Swiss

Initiative for e-waste management had been set up. It brings together the experience and

expertise of all the partners (MoEF, GTZ, seco) involved. The partners work in close

collaboration with manufacturers, users, recyclers, and NGOs to develop a sustainable e-

waste management system in India (eWaste Guide India, 2006).

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Obsolete

equipment

Obsolete

Functional

equipment

Functional

component

MetalsCRT Plastics PWBWires and

cables

Storage

Transport

Testing

Disassembling

Specific

recycling

channel

Specific

recycling

channel

Dismantling Stripping

Specific

recycling

channel

CopperConnectorsNude

PWBs

Specific

recyclingchannel

Precious

Metalrecovery

Specific

recyclingchannel

Refurbishing

Reuse

Burning

? ?

? ? ?

?

Obsolete

equipment

Obsolete

Functional

equipment

Functional

component

MetalsCRT Plastics PWBWires and

cables

Storage

Transport

Testing

Disassembling

Specific

recycling

channel

Specific

recycling

channel

Dismantling Stripping

Specific

recycling

channel

CopperConnectorsNude

PWBs

Specific

recyclingchannel

Precious

Metalrecovery

Specific

recyclingchannel

Refurbishing

Reuse

Burning

? ?

? ? ?

?

Figure 1.3: Simplified process sheet of the present Bangalore e-waste management system.Problematic processes are indicated by a flash; unknown or unclear processes are indicated with aquestion mark(Rochat, 2006).

As shown in Figure 1.3 the precious metal recovery is considered being one of the most

problematic processes in the e-waste management system in Bangalore. At present gold

recovery is seen as one of the most lucrative parts of precious metal recovery in the

backyard recycling. Most probably, this is a result of its high demand on the market. Since

2001, the gold price is continually growing (see Appendix VI). The most important use ofgold is in jewellery (Feneau, 2002). In 2002, 80 % of the global gold demand was used for

jewellery manufacture. India is the worlds greatest (absolute figures) gold consumer

because of its importance in Indian marriage ceremonies (Gold & precious metals, 2006).

Gold is found in electronic components like connectors and contacts, which are plated with

gold. Gold is used because of its excellent corrosion resistance and high electrical

conductivity. Such electronic components are part of a printed circuit assembly together with

a motherboard. In this thesis the terms printed circuit board (PCB) or printed wiring board

(PWB) are used to describe the whole assembly. Printed wiring boards are part of most

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9

electronic devices. According to Hagelken (2006) the most valuable metals compared to all

the e-waste are contained in PWBs. Approximately two third of the gold contained in a PC

are within the PWBs2.

Consequently, gold recovery is the most important division of the precious metal recovery in

Bangalore and printed wiring boards are considered as one of the most important fraction in

e-waste for the gold recovery.

1.5 Scope and aims of the thesis

1.5.1 Scope

The conducted case study of this thesis is integrated in the Indian project of secos global e-

waste programme. It provides background information for the planned activities of EWA to

upgrade the informal recyclers. It serves also to make a case for shifting the treatment ofhazardous fractions and critical recovery processes to the formal industry. To improve the

current system the existing practices as well as an alternative practice have to be analysed

properly. Today no detailed descriptions for the existing practices are available. The

accessibility to quantitative and qualitative data is poor and assessing an informal facility in

Bangalore in detail is doing pioneer work.

1.5.2 Aims and scientific questions

In this thesis, the gold recovery from PWBs is analysed as an example for the preciousmetals recovery from e-waste. In addition, an alternative scenario to the current pathway for

PWB recycling is evaluated. This leads to the two following aims (A) and scientific questions

(Q):

A 1: Providing scientific information of the quality of both the formal and informal gold

recovery processes conducted in Bangalore.

Q 1: What are the main substances and goods and their quantities used to recover

gold from PWBs conducting a gold recovery process in Bangalore?

Q 2: What are the main health and environmental hazards occurring during or as a

consequence of the gold recovery processes in Bangalore?

Q 3: What is the efficiency of PWB-recycling conducted in Bangalore?

A 2: Assessing an alternative to recycle PWB to the current recycling pathway and

comparing the two possibilities.

2

Average gold content in a PC=: 0,3 g (Streicher-Porte, 2006); Average weight of boards incomputers: 812 g 212g (Li et al., 2006), average gold concentration in PWB: 250 ppm(Hagelken, 2006); => 0,2 g 0,05g gold from PWB in PC

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Q 4: Is a shifting of the gold recovery process to an industrial smelter in Belgium

reasonable considering economical and environmental aspects?

1.6 Proceeding and structure of thesis

The aims and scientific questions are tackled making three different assessments, whichbuild up on each other.

To answer Q 1 and Q 2 a mass flow analysis is conducted and described in Chapter 2. In

this chapter, the investigated systems in Bangalore are described, quantified and interpreted

in order to determine the used substances and materials and to evaluate the main health

and environmental hazards.

In chapter 3, the recovery rates are determined, answering Q 3. Gold contents in the

different materials are quantified using a substance flow analysis.

In chapter 4,an alternative scenario to the investigated current recycling path of PWB with

the focus on gold recovery is evaluated as asked for in Q 4.

Chapter 5 presents the main findings and outlook, which are made during the different

assessments.

To assess an unorganised system like that of the backyard recyclers (informal sector) no

general practice exists. Therefore, the methodology for each assessment had to be

consistently adjusted to the existing situations. This iterative approach led to theproceedings, which can only be described in retrospect and are depicted in detail in each

chapter.

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Chapter 2 Gold recovery techniques and hazards

11

2 Gold recovery techniques and hazards

In this chapter, three processes to recover gold from e-waste are described. The main

materials used are determined and partly quantified. From this information, the major

hazard-hot spots to health and environment are identified.

2.1 Methodology

The system is described using the material flow analysis (MFA). Material flow analysis

(MFA) is a systematic assessment of the flows and stocks of materials within a system

defined in space and time. (Brunner and Rechenberger, 2004). The goal of an MFA is to

determine the in- and outputs of a process and to understand the flows within a system.

The analysis of material fluxes is an essential approach to gain a system comprehension

and an understanding of the processes occurring within the anthroposphere (Binder et al.,2001). Because of the law of the conservation of matter, the results of an MFA can be

controlled by a simple material balance comparing all inputs, stocks, and outputs of a

process. It is this distinct characteristic of MFA that makes the method attractive as a

decision-support tool in resource management, waste management, and environmental

management (Brunner and Rechberger, 2004). In this analysis the used terminology has

been developed according to the terminology defined in the Practical Handbook of

Material and Flow Analysis (Brunner and Rechenberger, 2004).

Subsequent the mainly used terms in this thesis are defined:

A substance is any (chemical) element or compound composed of uniform units. All

substances are characterised by a unique and identical constitution and are thus

homogenous.

The termmaterialis used for a solid matter composed of heterogeneous units.

A solution is the product of mixed substances and materials and is a heterogeneous

liquid.

A mixtureis the product of mixed substances and is a homogeneous liquid.

Processis a term used for the transformation and transport of materials and substances.

A techniqueis defined to be a sequence of processes.

A process stepis an activity within a process (sub-process).

The systemis defined by a group of processes, the interaction between these processes

and the system boundaries.

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The conducted material flow analysis comprises four steps:

System description:The system is characterised determining the system border and the

single process steps referring to the processes of each technique. Using information from

literature and various experts the processes and process steps of the system are

described.

Quantification: The in- and outputs of the system are measured and

calculated/estimated applying the principle of mass conservation.

Interpretation: The environmental hazard hot spots are detected with the beforehand

evaluations and are discussed.

Discussion:An overview of each evaluated system is given. In addition, some features

determined in the description and in the quantification of each process are discussed.

2.2 System Descript ion

2.2.1 System defini tion

The investigated system is part of the e-waste management system in Bangalore, as

illustrated in Figure 2.1. It consists of the gold recovery technique of pre-processed

(dismantled) printed wiring boards (PWBs).

Obsolete

equipment

Obsolete

Functionalequipment

Functionalcomponent

MetalsCRT Plastics PWB Wires &cables

Storage

Transport

Testing

Disassembling

SpecificRecycling

channel

SpecificRecycling

channel

Dismantling StrippingSpecific

Recycling

channel

CopperConnectorsNudePWBs

SpecificRecyclingchannel

PreciousMetal

recovery


Refurbishing

Reuse

Burning

? ?

? ? ?

?

Input

material

Gold

Liquids

Solids

Chemicals

Water

Dismantling

gold recovery

PWB

(Basic rawmaterial)

Recovery of

other precious

metals

Leaching

Purification

Separation

System boundary

Obsolete

equipment

Obsolete

Functionalequipment

Functionalcomponent

MetalsCRT Plastics PWB Wires &cables

Storage

Transport

Testing

Disassembling

SpecificRecycling

channel

SpecificRecycling

channel

Dismantling StrippingSpecific

Recycling

channel

CopperConnectorsNudePWBs


PreciousMetal

recovery


Refurbishing

Reuse

Burning

? ?

? ? ?

?

Input

material

Gold

Liquids

Solids

Chemicals

Water

Dismantling

gold recovery

PWB

(Basic rawmaterial)

Recovery of

other precious

metals

Leaching

Purification

Separation

Input

material

Gold

Liquids

Solids

Chemicals

Water

Dismantling

gold recovery

PWB

(Basic rawmaterial)

Recovery of

other precious

metals

Leaching

Purification

Separation

System boundary

Figure 2.1: MFA system definition; the system boundary is indicated with dashed lines; squaresrepresent processes, ovals substances, materials, solutions and mixtures.

The system consists of a gold recovery technique divided in several processes that are

required in order to recover gold from the input material. The technique is divided into

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three processes: Leaching, Separation and Purification. In the context of gold extraction,

leaching is the dissolution of a metal or mineral in a liquid (Marsden and House, 1992).

During the separation, the gold is extracted out of a solution or separated from a material.

Purification is the procedure of rendering something pure, i.e. cleaning it from impurities.

2.2.2 Data col lection

The description of the techniques is based on different data sources: Observations,

photographs, documentation, literature research and interviews. The observations were

made and photographs were taken during several visits of facilities conducting gold

recovery processes. Rough documentations of the conducted processes in the informal

facility already existed and were taken as a basis. These flowcharts were drawn by

Sahaas, an NGO active in waste management in Bangalore (Rodriguez, 2005). The main

literature resources were articles and books concerning gold mining. In gold mines, similartechniques are used to recover gold from the ore as they are used to recover gold from

pre-processed PWBs. The corresponding literature was then adapted to the specific

cases with the support of Dr. Richard Klinger (Central Environmental Laboratory of the

Karnataka State Pollution Control Board, Bangalore), Dr. Eddie Adriaenssens (Manager

Analytical Laboratory, UMICORE Precious Metals Refining, Hoboken, Belgium) and

Dr. Hartmut Schnberg (Department of Chemistry and Applied Biosciences, ETH Zurich).

2.2.3 Investigated facili tiesThree different gold recovery techniques conducted in Bangalore were investigated.

According to consultants working for GTZ (German technical organisation) these three are

the mainly conducted gold recovery techniques in Bangalore. Two of the techniques are

executed in several informal facilities; the other one in a formal facility.

2.2.3.1 Informal sector

Currently about 20 informal facilities in and around Bangalore are involved in the recovery

of precious metals from e-waste (Rodriguez, 2005). All of them presumably use the sametechnique to recover gold. Consultants of GTZ and EMPA are closely working together

with an informal association of recyclers called Eco BIRD. With the help of GTZ and

EMPA, it was possible to use these contacts and to work together with a gold recovery

unit of Eco BIRD. The following paragraph gives a short description of Eco BIRD and the

investigated unit.

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Eco BIRD

Picture 2.1: Eco BIRD (Rizwans) facility

In the informal sector in Bangalore, a recently founded association consisting of 11

recycling units called Eco BIRD exists. The word Eco stands for Eco-friendly and BIRD

is an acronym for Bifurcation, Identification, Recycling and Disposal. The 11 recyclingunits either deal with scrap, dismantle the equipment or recover precious metals.

The examined facility belongs to Rizwan Khan (president of Eco Bird) and is situated on a

roof (approx. 46m2) in Gowripalya, Padarayanapura, a suburb of Bangalore. There is a

room (approx. 16 m2) on top of the roof, where the furnace is situated and the materials

and substances are stored in. The containers with acidic liquids are placed outside.

Rizwan employs three workers between the age 10 and 20. Several other people are also

using his facility. The material that is treated by Rizwan per year is estimated to be 1800

kg with a gold production of 7200g (Bineesha, 2006).

To recover gold from e-waste two different techniques are conducted according to the

quality of the input material. If the gold concentration in the input material is low (low-

grade material), cyanide leaching is used. If the input material is high-grade material,

they conduct mercury amalgamation. Both of the processes are described in the

following chapters.

2.2.3.2 Formal sectorIn the formal sector, only one company, Surface Chem Finishers, is known conducting a

gold recovery process. It was possible to collaborate with this company and investigate

the exercised process. In the following paragraph a short description and scope of the

company is given.

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Surface Chem Finishers

Picture 2.2: E-Parisaraa Pvt. Ltd.

Surface Chem Finishers is an ISO 9001 2000 certified gold plating unit in Peenya

Industrial Estate, Bangalore. It is a sister company of E-Parisaraa Pvt. Ltd. which

recycles and dismantles e-waste. The vision of the director of the two companies is to be

eco-friendly and low cost. E-Parisaraa is located on the outskirt of Bangalore. About 5 %of the gold used for the gold plating in Surface Chem Finishers is recovered from e-

waste pre-processed at E-Parisaraa. Thus, gold recovery is only a side task of Surface

Chem Finishers.

Today there are 45 people working in the two companies. Three persons are involved in

the gold recovery process. At present, E Parisaraa is handling about one ton of e-waste

per day. According to Prakashchandra (Engineer of Surface Chem Finishers, E-Parisaraa

Pvt. Ltd.), approximately 920 kg of material is processed per year to recover gold. Thereof

440 g of gold is recovered per year.

2.2.4 Cyanide leaching at Eco BIRD

Cyanide has been used in the mining industry for more than 100 years to recover gold. It

is universally used because of its relatively low cost and great effectiveness of gold

dissolution. The reaction takes place in an alkaline environment, which is important for

economic and safety reasons. It has been shown that the maximum dissolution of gold,

silver, platinum and palladium in cyanide solution is at pH 10-10,5 (Dorin and Woods,

1991). The observed cyanide leaching technique was conducted at around pH 12 (seeTable 2.9). This is almost ideal for the leaching process as the loss of cyanide is very low

at pH 11,5 because the loss due to hydrogen cyanide (HCN) formation is very low

(Kulundaisamy et al., 2003). The main chemical reaction consists of four starting materials

and substances: water, oxygen, gold and cyanide. Cyanide is acting as the complexing

agent in the process and oxygen as an oxidiser (Marsden and House, 1992). However,

other elements contained in the electronic devices disturb this chemical reaction. For

example, the present copper will form cyanide complexes and cause an increased use of

cyanide. These copper-cyanide complexes will tend to inhibit the dissolution of gold.

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Detailed description of the technique

During a participating observation, this process had been investigated. The input material

is provided to the informal facility (see Appendix VII for details to the material preparation).

With this material, the process is conducted as it would be conducted with purchased

material and it is therefore an acceptable representative for the usual process. In the

following description the denominations (L1 P6) refer to the detailed and quantified

flowchart in chapter 2.3.2(Figure 2.5 and Figure 2.6).

Leaching

L 1: Lixiviation

The connectors are put into a plastic container and are doused withhot water. The gold leaching is initiated by adding substance 1(most probably potassium or sodium cyanide). Under mildly

oxidising conditions, the gold is dissolved. Adding cyanide results ina strong complex between cyanide and gold. The reaction known asElsner's Equation is:

4 Au(s) + 8 CN-(aq) + O2(g) + 2 H2O(l) 4 Au(CN)2-(aq) + 4 OH-(aq)

Because cyanide is one of the strongest ligands several othercomplexes are formed (ex.: [Ag(CN)2]

-, [Cu(CN)2]-, [Ni(CN)4]

-2).

Picture 2.3:Lixiviation withcyanide

L 2: Sieving / Washing

The components are removed from the pregnant (gold-bearing)solution and are washed with water. This is important in order todeplete the waste components as good as possible of their gold.These components are sometimes kept to recover copper in aseparate process.

Picture 2.4: Sievingof components

The pregnant solution has a brownish colour.

Picture 2.5:

Pregnant solution

Preparation of silver-salt

The silver-salt is prepared separately, conducting following processsteps:

PS 1: Heating

A silver ingot, nitric acid and hot water are mixed together andheated for approx. 5 minutes to dissolve the silver. The remainingsilver biscuit is then taken out, the solution is poured into a plasticbucket, and the tin container is washed with water.

Ag + 2 HNO3-> AgNO3+ NO2 + H2OPicture 2.6: Silvernitrate

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PS 2: Precipitation

Sodium chloride and water are added to the silver solution. The silver-salt precipitates assilver chloride, which is a white precipitation. Sodium nitrate has a high solubility in waterand is dissolved in the solution.

AgNO3+ NaCl -> AgCl + NaNO3

PS 3: Decantation

The liquid part of the reaction mixture is poured into anothercontainer. Silver chloride remains on the bottom of the bucket. Hotwater is used to clean the remaining slag from the nitric acid bydecantation.

Picture 2.7: Silverchloride

PS 4: Mixing

Water, an unknown salt and caustic soda are mixed with the white precipitation. Thereason for adding caustic soda (NaOH) is to keep an alkaline environment. After a furtherdecantation, the silver-salt enters the main process.

Separation

S 1: Gold formation

The separation is performed using the principles of the Merril-Croweprocess3(cementation with zinc). Aluminium-foils and the silver-saltare added to the gold bearing solution. Aluminium precipitates thegold and some silver because Al has the higher affinity to thecyanide ion than gold and silver. The silver reacts with the free

cyanide to prevent that the gold is dissolved again.3 [Au(CN)2]

-+ 2 Al -> 2 Al3++ 6 CN-+ 3 Au(s)

4 Ag(s) + 8 CN-(aq) + O2(g) + 2 H2O(l) 4 Ag(CN)2-(aq) + 4 OH-(aq)

Picture 2.8:Addingaluminium

S 2: Decantation / Filtering

The grey sludge is separated from the solution by pouring thesolution from one container to the other and keeping theprecipitation in the container. After doing so, the remaining slag isfiltered through a cloth.

Picture 2.9:Decantation

Picture 2.10:Filtering the mixture

3The Merril-Crowe process is a separation technique for removing gold from cyanide solution,usually using zinc.

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Purification

P 1: Melting

The cloth with its content is put into a crucible and is melted. Duringthe melting process lime (CaCO3) and two unknown substances areadded. These substances are flux materials that help to purify thegold. The purpose of substance 2 is to liberate the aluminium. Limeis then used to remove the substance 2. Lime precipitates basemetals such as aluminium as gelatinous hydroxides. Substance 3 isadded because the quality of the aluminium had been low grade.

During the melting process flux, slag is taken out for grinding. Picture 2.11: Melting

Picture 2.12: Fluxslag

P 2: Pouring

The rest of the melted slag is poured into water.

Picture 2.13: Pouring

P 3 Grinding

The process flux is grinded with an iron ball.

P 4: Boiling

Picture 2.14:Grinding

The solid (gold) pieces from the Pouring and the grinded flux are mixed and boiled to

remove the residual water.P 5: Partition

Nitric acid is added to separate the silver from gold. Silver nitrate issoluble in water and a gold material precipitates.

Ag + 2HNO3-> AgNO3+ NO2 + H2O

Picture 2.15:Partition of gold andsilver

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2.2.5 Mercury amalgamation at Eco BIRD

The gold recovery with mercury goes back to the 11th century. In the Middle Ages

alchemists tried to produce gold with base metals (which did not work).

The mercury amalgamation is based on the fact that mercury forms an amalgam4

withgold. With this procedure, the gold can be separated from the other metals present and

from impurities. The attraction of mercury is based on the fact that it is readily available,

cheap and efficient in recovering fine-grained gold (Commission of the European

Communities, 2000). It is a quite simple process using only three substances (mercury,

nitric acid and sodium bicarbonate) to recover the gold. However, it is an old technique

and no longer used in modern gold plants because of the known health and environmental

problems arising.


Leaching

The input material is filled in plastic containers (V=approx. 100l). Atfirst water is poured into the container, than the nitric acid (62%) isadded. Throughout this process, the metals (e.g. Cu) which arecontained in the input material, except gold, are dissolved in thesolution. Thus, the attaching parts of the gold pins to the mold aredissolved and the gold pins and flakes are released. The dissolvingtakes about 3 hours. During this time, it is stirred from time to timeand nitric acid and some water are added.

2 NO3-+ 4 H++ Cu -> 2 NO2 + H2O + Cu

++

With a sieve (mesh aperture approx. 4 cm x 4 cm) the remainingcomponents are taken out, washed with water and kept to processthem again in the cyanide leaching process. In the bluish solution,gold flakes remain and copper is dissolved.

The solution is filtered through a cloth to abstract the gold pins. Theremaining solution is then put into a big container to recover thecopper by adding an iron to the liquid. The iron is left in the containerfor several weeks. At the end, the copper sticks to the iron and canbe removed manually.

Picture 2.18:Lixiviation

Picture 2.19:Filtering

4Amalgam is any mixture or blending of mercury with another metal.

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Separation (Amalgamation)

The gold residues are put into a pan, inclusive the cloth used forfiltration. Mercury and some drops of nitric acid are added and mixedin the pan. The resulting alloy of gold and mercury is calledamalgam.

The cloth is washed with water and remaining non-gold-componentsare removed from the mixture.

Sodium Bicarbonate is added to the mixture and the mixture isdecanted.

The decanted slag is squeezed through the cloth the excess mercuryis recovered. The residue in the cloth is a hard lump of amalgam witha high concentration of gold.

A small amount of mercury and water is added to the amalgam lumpto make it softer. Then the lump is scrunched with a hammer-likeinstrument.

Picture 2.20:Gold-mercury-amalgam

Purification

Nitric acid is added to the amalgam and the resulting mixture isdecanted. Nitric acid dissolves part of the mercury, which isrecovered in a separate process. The decanted mixture is boiled in afurnace. Because mercury and nitric acid vaporise at a much lowertemperature than gold, these two substances can be removed byheat leaving the gold behind (Beard, 1987). The residual product inthe pan is a yellow gold powder.

In a last step, magnetic impurities are sorted out with a magnet. Picture 2.21:Nitrogen dioxideduring silverdissolving

Picture 2.22:Recovered goldpowder

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The following flowchart illustrates the above-described technique.

Copper recovery

Mercury recovery

Separation

Leaching

Connectors

Purification

Nitric acid

Mercury

Nitric acid

Gas / Fumes

Body

components

Wastecomponents

Waste

solution

Copper

solution

Water

Sodium

bicarbonate

Water

Mercury

Nitric acid

Water Mercury

solution

Gas / Fumes

Gold

Figure 2.3: Simplified flowchart of the mercury amalgamation.

A more detailed flowchart and more pictures can be found in Appendix IX and

Appendix X.

2.2.6 Gold stripping at Surface Chem Finishers

The director of Surface Chem Finishers developed a gold stripping substance with the

goal to conduct a more environmentally sound process than by using cyanide or mercury.

The concept is to dissolve the gold with the solution and collect it with electrolysis.


Leaching

The input material is put over night into a substance (gold stripper).During this time, the gold is leached out of the components.

The components are removed from the solution and are washed withhot water in order to deplete the waste components as good as

possible of their gold.

Picture 2.23:Lixiviation with gold

stripper

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Separation and Purification

The solution is filtered through a Whatman Filter and poured into abucket. The anode and cathode (titanium) are then put into thisbucket. They are connected to a small motor working with 5 V and0,5 A. Over night, the electrolysis is conducted and the gold is

collected at the cathode.Picture 2.24:Filtering

The cathode is removed from the solution and dried for 10 min at178C.

Picture 2.25:Electrolysis

The solid gold on the cathode is dissolved with aqua regia(HCl : HNO3= 3 : 1). This step is done under an exhaust to protectthe worker from inhalation of the toxic fumes.

Au + 4 HCl + HNO3= HAuCl3+ 2 H2O + NO

Picture 2.26:Dissolving gold inaqua regia

This solution is filtered again through a Whatman Filter.

Ferrous sulphate is added in order to precipitate the gold.

Fe++ Au2+ -> Fe3++ Au (s)

To accelerate the process the solution is heated. Purple colloidsprecipitate.

Picture 2.27:Heating thesulphate solution

The precipitation is then separated by decanting.

The remaining material is washed with water filtered through aBorosil Glass. The Glass is put into a heater to dry the material.

The result is a yellow gold powder.

Picture 2.28: Goldpowder after drying

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The following flowchart illustrates the above-described technique.

PurificationFerrous

sulphate

Water

Leaching

Connectors

Gold Stripper

Body

components (BC

Waste

solution 1Separation

Water

Aqua regia

Water

Vapour

Waste

solution 2

Gold

Figure 2.4: Simplified flowchart of the gold stripping.

2.3 Quantification

2.3.1 Data col lect ion

During the observations made for the description of the three gold recovery techniques

measurements were conducted to quantify the in- and outputs of the processes.

The in- and outputs were weighed with an electronic scale, measured with a measuring

cup or calculated by multiplying the volume with the density (assumed to be 1000 g / l). To

find out the volume, the diameter of the cylindrical containers and the height of thecontained liquid were measured. According to the received figures the mass flow could be

completed applying the law of conservation of mass (Input = Output), making feasible

assumptions and considering the chemical equations. In a further step the amounts of in-

and outputs were converted according to the functional unit one gram recovered gold.

The cyanide leaching and the gold stripping are quantified using provided material (the

material preparation is described in Appendix VII). The mercury amalgamation is only

partly quantified during an investigation of the informal facility doing usual business.

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The measurements for the different used and produced materials, substances, solutions,

mixtures and vapours are made according to following descriptions:

All the inputs of this process were measured except the cloth.

All the liquid outputs and the silver salt (which was also a mixture) were calculated

(volume * density).

The wet output components were weighed. The estimation was made that the weight

of the dry output components correspond approximately with the weight of the input

components (the amount of leached metals was neglected).

The amount of water vapour 1 results from subtracting the weight of the input

components from the wet weight of the output components.

The estimations for the produced nitrogen dioxide were made according to thechemical equation of the silver dissolution with nitric acid.

The deficiency of the mass in the flowchart was identified that it is most probably the

water, which had vaporised (especially during heating). This is proved plausible

considering that the evaporation enthalpy of water is 2257 kJ / kg, charcoal produces

25 MJ / kg and assuming a 30 % efficiency factor. Following for 4,91 kg (4880 g + 30

g) water vapour approximately 1,3 kg charcoal is used.

The quantified mass flows are shown in the subsequent flowcharts (Figure 2.5 and

Figure 2.6).

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Input material 1

12400

Energy (Coal)~ 2000

Hot water

11800

L 1: Lixiviation

4880

Substance 1111

Water5850

L 2: Sieving/ Washing12400

Body components

136

From "silver-salt-

preparation"Silver-salt

4570S 1: Gold formation

Aluminum foils28

Water2250

Cloth?

S 2: Decantation /

Filtering 18100Waste solution

Energy (Coal)~ 500 g

Lime28

P 1: Melting

Substance 21

Substance 310

P 2: Pouring

Water2050

P 3: Grinding3500

Silver solution 2Ag - recovery

P 4: Boiling30

52 g

Water125

P 5: Partition435


Nitric acid278 20

Substance 31

P 6: Melting?

Organic waste

0,6

Gold

Water vapour

Nitrogen

dioxide

Water vapour

Water vapour

Process flux

Solid (gold)

pieces

Estimations / Calculations

Assumption: Density of liquids = 1000g/l

Figure 2.5: Quantified flowchart of the cyanide leaching (main process); unit of numbers is gram.

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Energy (Coal)~ 500g

Silver70

PS 1: Heating28

Nitrogen dioxide

Nitric acid128 4

Silver

Water1000

Sodium chloride236

PS 2: Precipitation

Water5600

Hot water2000

PS 3: Decantation

Water1500

PS 4: Mixing4570

Silver-salt

Unknown salt81 6160


Caustic soda147

Estimations / Calculations

Assumption: Density of liquids = 1000g/l

Figure 2.6: Preparation of silver-salt used in the main process of the cyanide leaching; unit ofnumbers is gram.

The following tables (Table 2.1 and Table 2.2) give an overview of all the in- and outputs

and are quantified according to the functional unit (one gram recovered gold). In

addition, the further destinations of the outputs are noted.

Table 2.1: Input materials of the cyanide leaching per gram recovered gold

Input g / g gold

Input material 2,07E+04Water 5,36E+04Substance 1 (containing cyanide) 1,85E+02Aluminium 4,67E+01Nitric acid 6,77E+02Lime 4,67E+01Silver 1,17E+02Sodium chloride 3,93E+02

Caustic soda 2,45E+02Unknown salt 1,35E+02Unknown substances (2, 3) 2,00E+01

Table 2.2: Output materials of the cyanide leaching per gram recovered gold

Output g / g gold Destination

Body components 2,07E+04 Solid waste streamWater vapour 8,41E+03 AirWaste solution 3,02E+04 DrainSilver solutions 1,68E+04 Recovery

Fumes (Nitrogen dioxide) 8,00E+01 AirSilver 6,67E+00 Process cycleGold 1,00E+00 Sale

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The silver solutions are further treated with a silver recovery technique. This technique is

not included in the system boundary. However, a short description of the process is given

in the subsequent paragraph.

Silver Recovery

The silver from the silver solutions (output) is recovered using sodium chloride, which

reacts with silver producing silver chloride. In a further step iron is added which

precipitates the silver, acting as a reducing agent (flowchart see Appendix XI). The

precipitation is then melted and solid silver is recovered. Using this procedure in the

above process 50 grams of silver, were recovered. Thus per gram of produced gold 83

grams of silver are recovered. This means that during the cyanide leaching 27 grams of

silver are lost per gram recovered gold.

2.3.3 Mercury amalgamation at Eco BIRD

This technique was investigated during a visit of the informal facility doing usual business.

The in- and outputs were only partly measured.

The input material of the observed process was connectors assumingly from PWBs of

telephones. From 14,3 kilograms of connectors 54 grams of gold was recovered. During

this technique, more than 130 g of mercury was used. The other used materials have not

been measured. The in- and outputs and their further destinations are listed below.

Table 2.3: Input materials of the mercury amalgamation per gram recovered gold

Input g / g gold

Input material (connectors) 2,64E+02Mercury 3,59E+00Sodium bicarbonateWater

Table 2.4: Output materials of the mercury amalgamation per gram recovered gold

Output g / g gold Destination

Body components Solid waste streamGas / Fumes (i.e. water vapour, nitrogen dioxide) AirCopper solution RecoveryWaste solution DrainMercury solution RecoveryMercury 0,07E+00 Process cycleGold 1,00E+00 Sale

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2.3.4 Gold stripping at Surface Chem Finishers

The measurements for the different in- and outputs are made according to following

descriptions:

All the inputs of this process were measured except the water used for the purification.

The wet output components were weighed. The estimation was made that the weight

of the dry output components correspond approximately with the weight of the input

components (the amount of leached metals was neglected).

The amount of the vapour results from subtracting the weight of the input components

from the wet weight of the output components.

The waste solution 1 was measured using a measuring cup.

The waste solution 2 was not measured.

Figure 2.7 illustrates the processes and the quantified in- and outputs of gold stripping,

showing the mass flow as it was determined during the on site observation. A flowchart

illustrating the different process steps can be found in Appendix XII

1050

200 50

4250 1050

131 2400

200

66 ?

?

0,162

PurificationFerrous

sulphate

Water

Leaching

Connectors

Gold Stripper

Body

components

Waste

solution 1Separation

Water

Aqua regia

Water

Vapour

Waste

solution 2

Gold

Figure 2.7: Simplified and quantified flowchart of the gold stripping; unit of numbers is gram.

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The following tables (Table 2.5 and Table 2.6) give an overview of all the in- and outputs

of the process and their further destinations are noted.

Table 2.5: Input materials of the gold stripping per gram recovered gold

Input (g) Per g gold

Input material 6,48E+03Water >2,75E+04Gold Stripper 1,23E+03Hydrochloric acid 5,93E+02Nitric acid 2,16E+02Ferrous sulphate 4,07E+02

Table 2.6: Output materials of the gold stripping per gram recovered gold

Output (g) Per g gold Destination

Body components 6,48E+03 Solid waste streamVapour 3,09E+02 AirWaste solution 1 1,48E+04 Treatment plantWaste solution 2 >1,48E+04 Treatment plantGold 1,00E+00 Gold plating

2.4 Interpretation

Based on the system descriptions and quantifications the critical outputs, concerning the

environment and human health, of the three gold recovery processes were identified.

These hazard-hot spots are listed and described for each process. From some of these

critical outputs samples were taken and tested for a range of metals that are known to

have a high potential to bioaccumulate in the environment. Additional on site observations

during the conducted processes are qualitatively discussed. A short description of the

identified substances and metals can be found inAppendix XV.


2.4.1.1 Major hazard-hot spots

1. Fumes: The most obvious contamination during the observation was the nitrogen

dioxide, a red-brown fume that was generated during the dissolution of silver, which

irritated the eyes and provoked dizziness. The corresponding chemical equation is:

Ag + 2 HNO3-> AgNO3 + NO2 + H2O.

2. Waste solution: The waste solution is poured untreated into the drain. Since there is

no canalisation system, which ends up in a wastewater treatment plant the waste

solution ends up directly into the environment (water, soil and air) and can pollute the

adjacent communities and waters.

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3. Body components: The body components probably end up in the solid waste stream.

This means that they are piled up on the streets for some time and in the best-case

end up in the landfill. In both cases over a certain amount of time, the contents in the

body components will be released to the environment. A study from Jang and

Townsend (2003) showed that lead will leach out from PWB when landfilled.

Samples of the waste solution and the body components were collected and tested for the

concentration of a range of metals (see Appendix XIV and Appendix XIII). The most

relevant metals to the environment according to Smidt (2006) and their concentration in

the body components, respectively in the waste solution are presented in

Table 2.8 and Table 2.7. In addition, aluminium is also listed in Table 2.7 because of its

elevated concentration in the wastewater.

Table 2.7: Metal concentrations in the waste solution of the cyanide leaching

Table 2.8: Metal concentration in the body components of the cyanide leaching

Element Concentration (ppm) Stdev (ppm)

Copper (Cu) 229250 2333Nickel (Ni) 3200 141

Lead (Pb) 22650 1626

Tin (Sb) 5100 283

Zinc (Zn) 23950 4596

2.4.1.2 Addit ional on site observations

The handling of the materials, which contain cyanide salts and nitric acid, is very frivolous

and no personal protection like gloves, goggles or masks are used. All of the workers

have small burns in the skin of the palms and a yellowish discoloration of skin and nails

which are most probably symptoms of the contact with nitric acid. Beverages and food are

consumed while handling the different and often hazardous substances. Thus, the

substances can enter the body through absorption or ingestion.

Element Concentration (ppm) Stdev [ppm]

Aluminium (Al) 1315 55Arsenic (As)

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2.4.1.3 Comparison to the Swiss legislation

To give a quantitative statement to the possible hazards the results of the sampling are

put into relation with the allowed concentrations to discharge industry effluents into water

in Switzerland, according to Annex 3, GschV (Schweizerische Eidgenossenschaft, 1998).

The Swiss regulation of water pollution control limits the effluent concentration from

industry, amongst others, of the pH, eight metals and the free cyanide ion. These metals

(plus mercury, molybdenum and thallium) are the most relevant heavy metals to the

environment (Smidt, 2006). In the following table, the requirements of the Swiss regulation

are compared with the concentration of the wastewater of the cyanide leaching at Eco

BIRD. The ratio indicates the deviation of the values of the waste effluent from the cyanide

leaching conducted at Eco BIRD, in Bangalore, to the Swiss thresholds.

Table 2.9: Comparing the thresholds of the Swiss legislation (see Appendix XVI) of industrialwaste water with the found concentration in the waste solution of the cyanide leaching

Parameter Request GschV Ratio Waste water Eco BIRD

pH-value 6,5 to 9,0 12Arsenic (As) 0,1 mg / l < 5

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Table 2.10: Metal concentration in the body components of the gold stripping

Element Concentration (ppm)

Copper (Cu) 223000Nickel (Ni) 5000

Lead (Pb) 2000

Tin (Sb) 11000Zinc (Zn) 33000

2.4.3.2 Addit ional on site observations

During the on site observations no obvious hazards could be observed. The handling of

the substances has been very careful and both an exhaust system and personal

protection equipment has been used.

2.5 Discussion

2.5.1 Suitabili ty of the method

The method is based on the scientific concept of the mass flow analysis and was adjusted

according to the encountered situations and the available resources. It has been a

suitable tool to make a quantitative evaluation of the processes. The method helps

increase the knowledge of the conducted processes and the gained data are transparent

and objective. One of the major problems in using this method (MFA) in regions in

developing countries is the availability of reliable data (Binder et al., 2001). Addressing

this problem experimental data is collected in addition to literature research andinterviews. Within the time limits of this thesis and having a certain amount of provided

material, only two of the three encountered gold recovery techniques could be fully

quantified. Furthermore, a repetition and improvement of the measurements was not

possible. Thus, it is a momentary recording of the process using the provided material.

This leads to the fact that statistical procedures cannot be applied to give the data more

weight. Nevertheless, it was possible to describe all investigated gold recovery processes

qualitatively in detail and to quantify two of the processes.

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