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

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 Mining: Evolution or l l G ld Mi i G ld Mi i E E l ti l ti More Pollution? More Pollution? Marcello M. Veiga g Associate Professor Visiting Professor, Dept Mining Engineering Dept Mining Engineering University of São Paulo, Brazil

Artisanal Mining The term artisanal mining encompasses all small, medium, informal, legal and illegal miners who di i f l l l d ill l i h use rudimentary processes to extract gold and other minerals from secondary and primary ores Ghana Ghana Ghana Ghana Brazil Brazil

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

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

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

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

Sudan Sudan

Children in Artisanal Mining g ILO (2004) estimated 2 million children working ( ) g in artisanal mining Mozambique Mozambique Laos Laos

Children in Artisanal Mining Guinea Guinea Suriname Suriname Photo: Rukimini Photo: Rukimini

Causes of Poor Artisanal Mining Practice Causes of Poor Artisanal Mining Practice g • Disorganization & Disorganization & Transience • No technical assistance • Lack of education of miners • Lack of education of miners • Inadequate regulations • Financial barriers • Lack of support from L k f t f mainstreams of Society • PO POVER PO POVER VERTY VERTY Tanzania Tanzania

Environmental, Health & Social Problems Caused Environmental, Health & Social Problems Caused , by Artisanal Gold Mining by Artisanal Gold Mining • Water siltation W t ilt ti • Landscape degradation p g • Prostitution, Drugs & Crimes Crimes • Money laundering • Deforestation • TB, malaria, tropical TB malaria tropical diseases, HIV/AIDS • Mercury & Cyanide pollution pollution Indonesia Indonesia

Galangan, Kalimantan, Indonesia G G Galangan, Kalimantan, Indonesia g g , , , , • 10,000 illegal artisanal miners invaded area , g • 200 km² of forest (Orangutans habitat) destroyed • 2 tonnes/a Hg lost Before After

Burning Amalgam Photo K. Telmer Indonesia

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) • Legalization (preferred by MOST L li ti ( f d b 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)

SURUCUCU MONTE ALEGRE Fish & water Fish & water Fish & hair Fish & hair RIO NEGRO 125 samples 423 samples Fish & water TARTARUGALZINHO 150 samples Fish, hair, sediment , , 85 samples GURUPI Hair, blood, urine, sediment, swine 292 292 samples l TAPAJÓS Hair, fish, water, sediments SERRA PELADA 4447 samples Hair, soil, sediments 101samples CARAJÁS ACRE Fish, hair, water, sediments Water, hair, blood, 155 samples 155 samples fish, sediment, soil, fi h di t il 1022 samples MADEIRA CUMARU-TUCUMÃ Fish, water, sediments Water, hair, blood, sediments 180 samples p 144 samples 144 samples NORTH of MATO GROSSO RONDÔNIA Water, sediments Hair 150 samples 1059 samples Number of samples analyzed for Hg in the Amazon: 8333 samples Source: Alberto Rogerio B. Silva

Monitoring in Artisanal Mining Monitoring in Artisanal Mining g g g g No fair balance!!! No fair balance!!! Solutions S l ti Solutions S l ti for the Problem for the Problem Monitoring Monitoring g and Studies and Studies

Examples of Ineffective Laws: Examples of Ineffective Laws: Brazilian Approach Brazilian Approach � Law 97.507/89 – Hg and CN prohibition “N “No artisanal mining site is allowed to use Hg or ti l i i it i ll d t H 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 artisanal miners in Tapajós, ti l i i T jó Brazil using Hg and CN without any license Brazil

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

Processing Centers in Indonesia Processing Centers in Indonesia • They use the most They use the most rudimentary process • 25 to 40% of Au 25 t 40% f A recovered (LOW) • Adding Hg into the Grinding Circuit Grinding Circuit • About 40-50% of Hg added is lost dd d i l t • P.C. owners keep the p tailings with Hg & Au as a payment a payment

Processing Centers in Indonesia Processing Centers in Indonesia Hg-contaminated Tailings Are Submitted to Cyanidation Cyanidation

Processing Centers in Indonesia Processing Centers in Indonesia Tailings with Tailings with Hg & cyanide reach the reach the streams

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

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

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

Processing Centers in Ecuador Processing Centers in Ecuador g 92 cyanidation 92 cyanidation tanks in the town tanks in the town of Portovelo leaching Hg- contaminated contaminated tailings g

Processing Centers in Ecuador Processing Centers in Ecuador g Tailings with Hg and cyanide Hg and cyanide are dumped p into the A Amarillo River ill Ri

Processing Centers in Brazil Processing Centers in Brazil g Mi Miners use Cu-amalgamating plates to recover C l i l the “easy” more accessible gold

Processing Centers in Brazil Processing Centers in Brazil g • Hg-tailings are leached with NaCN with NaCN • Hg-cyanide in tailings reach the rivers h th i • 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 Brazil, S Brazil, São Chico, o Chico o Chico, ppm Hg Amazon Amazon

Gl Global Mer obal Mercur ury Pr y Project oject Mean Hg in fish Number of Sites (ppm or mg/kg) (ppm or mg/kg) samples samples Brazil São Chico 2.53 73 0.36 161 Creporizinho Indonesia Galangan Indonesia 0.21 0.21 264 264 Galangan 0.58 156 Talawaan L Laos Luang Prabang 0 066 0.066 65 65 Sudan Blue Nile 0.05 108 Tanzania Rwamagasa 0.13 285 Zimbabwe Zimbabwe Kadoma 0 41 0.41 52 52 Kadoma

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

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 j y equipment is locally manufactured manufactured Indonesia Indonesia Indonesia Indonesia

Demonstrating Cleaner Demonstrating Cleaner Sudan Sudan Techniques q Laos Laos

Demonstrating Cleaner Demonstrating Cleaner Techniques q Tanzania Tanzania

Demonstrating Cleaner Zimbabwe Zimbabwe Demonstrating Cleaner Techniques q Brazil Brazil

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

Zig Zig- -zag Sluice zag Sluice Indonesia Indonesia Zig-zag sluices increase increase chances of gold being capture by being capture by carpet Laos Laos