University of British Columbia Norman B. Kevil Institute of Mining - - PowerPoint PPT Presentation

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University of British Columbia Norman B. Kevil Institute of Mining - - PowerPoint PPT Presentation

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University of British Columbia Norman B. Kevil Institute of Mining Engineering Vancouver Canada Processing Centers in Artisanal and Processing Centers in Artisanal and S S Small-scale Gold Mining: Evolution or Small ll ll scale Gold

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University of British Columbia

Norman B. Kevil Institute of Mining Engineering Vancouver Canada

Processing Centers in Artisanal and Processing Centers in Artisanal and S ll S ll l G ld Mi i E l ti l G ld Mi i E l ti Small Small-scale Gold Mining: Evolution or scale Gold Mining: Evolution or More Pollution? More Pollution? Marcello M. Veiga g

Associate Professor

Visiting Professor, Dept Mining Engineering Dept Mining Engineering University of São Paulo, Brazil

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Artisanal Mining

The term artisanal mining encompasses all small, di i f l l l d ill l i h medium, informal, legal and illegal miners who use rudimentary processes to extract gold and

  • ther minerals from secondary and primary ores

Ghana Ghana Ghana Ghana Brazil Brazil

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Artisanal Mining

About 30 million artisanal miners extracting more than 30 minerals in virtually all developing countries minerals in virtually all developing countries

Venezuela Venezuela Zimbabwe Zimbabwe

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Gold price increasing = More people involved Gold price increasing More people involved

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This is the biggest gold rush the This is the biggest gold rush the world has ever seen

  • 10 to 15 million artisanal

miners producing around 350 tonnes Au/a a ou d 350 to es u/a in more than 70 countries countries

  • About 50-100 million

people directly and indirectly involved in indirectly involved in artisanal gold mining

Guinea

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In the world as many as 9 million women (50% involved in gold mining)

Tanzania

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Sudan Sudan

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Children in Artisanal Mining

ILO (2004) estimated 2 million children working

g

( ) g in artisanal mining

Mozambique Mozambique Laos Laos

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Children in Artisanal Mining

Suriname Suriname Guinea Guinea Photo: Rukimini Photo: Rukimini

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Causes of Poor Artisanal Mining Practice Causes of Poor Artisanal Mining Practice

  • Disorganization &

g

Disorganization & Transience

  • No technical assistance
  • Lack of education of miners
  • Lack of education of miners
  • Inadequate regulations
  • Financial barriers

L k f t f

  • Lack of support from

mainstreams of Society

  • PO

POVER VERTY PO POVER VERTY

Tanzania Tanzania

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Environmental, Health & Social Problems Caused Environmental, Health & Social Problems Caused W t ilt ti , by Artisanal Gold Mining by Artisanal Gold Mining

  • Water siltation
  • Landscape degradation

p g

  • Prostitution, Drugs &

Crimes Crimes

  • Money laundering
  • Deforestation

TB malaria tropical

  • TB, malaria, tropical

diseases, HIV/AIDS

  • Mercury & Cyanide

pollution

Indonesia Indonesia

pollution

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Galangan, Kalimantan, Indonesia Galangan, Kalimantan, Indonesia G g , , G g , ,

  • 10,000 illegal artisanal miners invaded area

, g

  • 200 km² of forest (Orangutans habitat) destroyed
  • 2 tonnes/a Hg lost

Before After

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Burning Amalgam

Indonesia Photo K. Telmer

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What Are the Solutions? What Are the Solutions?

  • Monitoring, monitoring and more

Monitoring, monitoring and more monitoring (preferred by the MAJORITY of researchers) MAJORITY of researchers) L li ti ( f d b MOST

  • Legalization (preferred by MOST

Governments)… but NO enforcement )

  • Processing Centers (being adopted in

g ( g p MANY artisanal mining regions)

  • Education and technical assistance

(ignored by ALL Governments) (ignored by ALL Governments)

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SURUCUCU Fish & water MONTE ALEGRE Fish & hair Fish & water 125 samples RIO NEGRO Fish & water 150 samples Fish & hair 423 samples TARTARUGALZINHO Fish, hair, sediment , , 85 samples GURUPI Hair, blood, urine, sediment, swine 292 l 292 samples TAPAJÓS Hair, fish, water, sediments 4447 samples SERRA PELADA Hair, soil, sediments ACRE Water, hair, blood, fi h di t il 101samples CARAJÁS Fish, hair, water, sediments 155 samples fish, sediment, soil, 1022 samples MADEIRA Fish, water, sediments 180 samples CUMARU-TUCUMÃ Water, hair, blood, sediments 144 samples 155 samples NORTH of MATO GROSSO Water, sediments 150 samples RONDÔNIA Hair 1059 samples p 144 samples

Number of samples analyzed for Hg in the Amazon: 8333 samples

Source: Alberto Rogerio B. Silva

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Monitoring in Artisanal Mining Monitoring in Artisanal Mining g g g g

No fair balance!!! No fair balance!!!

S l ti S l ti Solutions Solutions for the Problem for the Problem Monitoring Monitoring g and Studies and Studies

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Examples of Ineffective Laws: Examples of Ineffective Laws: Brazilian Approach Brazilian Approach

Law 97.507/89 – Hg and CN prohibition “N ti l i i it i ll d t H “No artisanal mining site is allowed to use Hg or CN without previous permit issued by the environmental authority. Environmental crimes are punishable with fines and jail” p j Reality: y Survey showed 99.3% of ti l i i T jó artisanal miners in Tapajós, Brazil using Hg and CN without any license

Brazil

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PROCESSING CENTERS: Miners Take Their PROCESSING CENTERS: Miners Take Their PROCESSING CENTERS: Miners Take Their PROCESSING CENTERS: Miners Take Their Ores to Be Processed by Trained Operators Ores to Be Processed by Trained Operators

Venezuela

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Processing Centers in Indonesia Processing Centers in Indonesia

  • They use the most

They use the most rudimentary process 25 t 40% f A

  • 25 to 40% of Au

recovered (LOW)

  • Adding Hg into the

Grinding Circuit Grinding Circuit

  • About 40-50% of Hg

dd d i l t added is lost

  • P.C. owners keep the

p tailings with Hg & Au as a payment a payment

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Processing Centers in Indonesia Processing Centers in Indonesia

Hg-contaminated Tailings Are Submitted to Cyanidation Cyanidation

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Processing Centers in Indonesia Processing Centers in Indonesia

Tailings with Tailings with Hg & cyanide reach the reach the streams

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Processing Centers in Colombia Processing Centers in Colombia g

Owners of the Processing Centers Use NaCN to Extract Residual Gold from Hg-Tailings

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Processing Centers in Zimbabwe Processing Centers in Zimbabwe

  • Cu-Hg Plates amalgamate the whole ore
  • Hg-contaminated tailings are submitted to

cyanidation in Processing Centers cyanidation in Processing Centers

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Processing Centers in Ecuador Processing Centers in Ecuador g

  • Poor extraction of gold from the ore brought by

miners to one of the 110 Centers in Portovelo miners to one of the 110 Centers in Portovelo

  • P.C. owners retain the tailings
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Processing Centers in Ecuador Processing Centers in Ecuador g

92 cyanidation 92 cyanidation tanks in the town tanks in the town

  • f Portovelo

leaching Hg- contaminated contaminated tailings g

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Processing Centers in Ecuador Processing Centers in Ecuador g

Tailings with Hg and cyanide Hg and cyanide are dumped p into the A ill Ri Amarillo River

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Processing Centers in Brazil Processing Centers in Brazil g

Mi C l i l Miners use Cu-amalgamating plates to recover the “easy” more accessible gold

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Processing Centers in Brazil Processing Centers in Brazil g

  • Hg-tailings are leached

with NaCN with NaCN

  • Hg-cyanide in tailings

h th i reach the rivers

  • 60% of fish >0.5 ppm Hg

pp g

  • WHO max guideline for

edible fish = 0 5 ppm Hg edible fish = 0.5 ppm Hg

  • One fish sample = 22

Brazil S Brazil São Chico

  • Chico

ppm Hg

Brazil, S Brazil, São Chico,

  • Chico,

Amazon Amazon

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Gl Global Mer

  • bal Mercur

ury Pr y Project

  • ject

Sites Mean Hg in fish (ppm or mg/kg) Number of samples (ppm or mg/kg) samples Brazil São Chico 2.53 73

Creporizinho

0.36 161 Indonesia

Galangan

0.21 264 Indonesia Galangan 0.21 264

Talawaan

0.58 156 L 0 066 65 Laos Luang Prabang 0.066 65 Sudan Blue Nile 0.05 108 Tanzania Rwamagasa 0.13 285 Zimbabwe

Kadoma

0 41 52 Zimbabwe Kadoma 0.41 52

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Mercury Forms Soluble Complexes with Mercury Forms Soluble Complexes with y p y p Cyanide Cyanide

  • [Hg(CN) ]2- which is stable at pHs above 8 5

[Hg(CN)4] which is stable at pHs above 8.5 and Hg(CN)2 (aq), stable at pH below 7.8

  • These complexes can be either methylated in

the sediments or directly bioaccumulated

V l PC t l (2011) J l f Cl P d ti 19 1125 1133 Velasquez,P.C.et al. (2011). Journal of Cleaner Production. v.19, p.1125-1133.

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Education: Demonstration of Education: Demonstration of Cleaner Techniques q

  • The pieces of
  • The pieces of

equipment were discussed and designed with miners designed with miners

  • The majority of the

Indonesia Indonesia

j y equipment is locally manufactured

Indonesia Indonesia

manufactured

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Demonstrating Cleaner Demonstrating Cleaner Techniques q

Laos Laos Sudan Sudan

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Demonstrating Cleaner Demonstrating Cleaner Techniques q

Tanzania Tanzania

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Demonstrating Cleaner Demonstrating Cleaner Techniques q

Brazil Brazil Zimbabwe Zimbabwe

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Demonstrating Availability of Gold Concentrators Demonstrating Availability of Gold Concentrators and How to Improve Efficiency and How to Improve Efficiency and How to Improve Efficiency and How to Improve Efficiency

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Zig Zig-

  • zag Sluice

zag Sluice

Indonesia Indonesia

Zig-zag sluices increase increase chances of gold being capture by

Laos Laos

being capture by carpet

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Demonstration of Simple Solutions to Reduce Demonstration of Simple Solutions to Reduce Hg Vapor Exposure Hg Vapor Exposure

Mi b i l i Miner burning amalgam in an open pan Hg vapor exposure of the whole family C b di Cambodia Photo: Tom Murphy

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Home-made Retort Using Kitchen Bowls

wet sand

  • e

ade eto t Us g tc e

  • s

wet sand is added to seal mercury is mercury is condensed on condensed on condensed on condensed on the glass bowl the glass bowl and recovered and recovered and recovered and recovered

amalgam in a g small cup

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Retort Made of Kitchen Bowls Using a enameled steel bowl steel bowl Adding a small stainless steel stainless steel salad cup

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Retort Made of Kitchen Bowls

Zimbabwe Zimbabwe Laos Laos

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Retort Made of Kitchen Bowls

Sudan Sudan

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Kitchen Bowl Retort Kitchen-Bowl Retort

Sealed with wet sand Ecuador Ecuador

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Kitchen Bowl Retort Kitchen-Bowl Retort

Colombia Colombia

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Kitchen Bowl Retort Kitchen-Bowl Retort

Chile Chile

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Brazil Brazil

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Replacing Hg with Cyanide Replacing Hg with Cyanide Intensive Cyanidation of Concentrates Intensive Cyanidation of Concentrates

(Field Tests in Ecuador) (Field Tests in Ecuador)

  • 95% of gold

extracted from

( ) ( )

extracted from gravity concentrate i 8 h f i t i in 8 h of intensive cyanidation in a small ball-mill

  • Use of activated

Use of activated carbon C id

  • Cyanide was

destroyed with

Ecuador

bleach

Veiga et al (2009). J. Cleaner Production v.17, p.1373–1381

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Training the Trainers Training the Trainers

Indonesia Indonesia Brazil Brazil Sudan Sudan Laos Laos

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Brazil Brazil

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Training Material Training Material Training Material Training Material

do seu do seu “T k f T ” Brazil Brazil “Take care of your Treasure”

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Training Material Training Material Training Material Training Material

Laos Laos

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Training Material Training Material Training Material Training Material

Indonesia Indonesia

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Training Material Training Material Training Material Training Material

Sudan Sudan

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There is Light at the There is Light at the g End of the Tunnel End of the Tunnel

  • Artisanal miners are

b i ll l becoming small-scale miners

  • More responsible and

cleaner gold production cleaner gold production

  • No mercury being used
  • Cyanide is destroyed

after use after use

Ecuador

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Conclusion Conclusion

Legal approach to introduce cleaner production in

Conclusion Conclusion

  • Legal approach to introduce cleaner production in

artisanal gold mining areas is ineffective

  • Monitoring is important but not enough

P i C t t ti lth i th

  • Processing Centers are concentrating wealth in the

hands of owners and creating Hg & CN pollution

  • Hg-cyanide environmental effects are still unknown

S l ti i d ti d t t h i l

  • Solution is education and permanent technical

assistance to miners

  • Solution is evolution of artisanal miners to become

responsible small miner responsible small miner

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We need to change this We need to change this perception:

“It’s easier for a man to become an artisanal become an artisanal miner than for a miner t b ” to become a man”

A Brazilian artisanal gold miner g