MERCURY POLLUTION ABATEMENT PROJECT MENART GEOVENTURES ENT. LTD P. O. BOX 237 TARKWA GHANA PRESENTATION AT BRUSSELS BY PROF. S. AL-HASSAN 13TH - 15TH DECEMBER, 2010

OUTLINE OF PRESENTATION Objective ASSM Mining methods in Ghana Available alternatives Direct smelting – the technique Laboratory and field trials Challenges Conclusions

OBJECTIVE Identify and introduce techniques or processes to eliminate the use of mercury by artisanal and small-scale gold miners (ASM) in Ghana

MAP OF AFRICA SHOWING LOCATION OF GHANA Area is about 230 020 km2 Population is about 21 million Climate is tropical

GEOLOGICAL MAP OF GHANA SHOWING ROCK FORMATIONS THAT CONTAIN GOLD

LOCATION OF SMALL-SCALE MINNG DISTRICT CENTRES, GHANA District Centres Location Region Tarkwa, Bibiani, & Asankragua Western Assin Fosu, & Dunkwa-on-Offin Central Akim Oda Eastern Bolgatanga Upper East

ASSM GOLD & DIAMOND PRODUCTION Total Ghana Production Year Gold Prodn (oz) Diamond Prodn (carats) 2000 2,457,152 878,011 2001 2,381,345 1,090,072 2002 2,236,833 963,493 2003 2,274,627 904,089 2004 2,031,971 905,344 2005 2,138,944 1,065,923 2006 2,342,722 972,991 2007 2,628,290 839,235 SSM Contribution 1989 Gold 2% Diamonds 40% 2001 Gold 6% Diamonds 95% 2007 Gold 12% Diamonds 98% Source: Minerals Commission, Ghana

ASSM MINING METHODS IN GHANA Washing and Panning (alluvials along rivers) Dredging Shallow pitting (near surface placers) Underground mining (reefs) Tailings and waste dumps (of old closed mines)

MINING IN DRY AREA (ELUVIAL) 90% grain size greater than 1 mm

CONCENTRATION (DRY AREA) Washing Winnowing

MINING OF ALLUVIAL DEPOSITS

MINING HARD ROCK (REEFS)

SSM DREDGING IN GHANA (SUCTION)

MILLING (HARD ROCK)

FLOW SHEET FOR AMALGAMATION OPERATIONS Ore (hard rock)  crushing/grinding gravity concentration mercury  amalgamation filtration of excess mercury  liquid mercury burning of amalgam  mercury vapour sponge gold smelting bullion

SLUICING

PANNING

GOLD CONCENTRATE IN A PAN

AMALGAMATION

SQUEEZING EXCESS MERCURY FROM AMALGAM

FIREPLACE FOR BURNING AMALGAM

SPONGE GOLD

GATHER AND SELL

OPEN HEATTH FOR SMELTING GOLD

MERCURY LOSS Spillage during amalgamation Poor amalgam distillation Disposal of amalgamation tailings Further processing of sponge gold it is estimated that for every gram of gold recovered at least 0.43g of mercury escapes

ALTERNATIVE PROCESSES TO AMALGAMATION Physical methods Shaking tables , special sluices, Centrifugal concentrators. Chemical methods Coal gold agglomeration IGoli Haber process Cyanide leaching Direct Smelting

SLUICING Method Equipment/ Process Principle Applicability Physical Sluice Gravity concentration leading to production of a rough concentrate that has to be cleaned further Used in virtually all small scale mining centres as a conventional rougher concentration unit.

COAL-GOLD AGGLOMERATION Method Equipment/ Process Principle Applicability Physico-chemical Coal-Gold Agglomeration Agglomeration of the gold particles and coal, followed by flotation with diesel, kerosene and other oils. The float concentrate has to be processed and smelted The process has been tested in Australia, South Africa, Brazil and Tanzania. It appears that despite its apparent attractions, it was never actually put in to operation and more research is required.

Igoli Process Method Equipment/ Process Principle Applicability Chemical IGoli process Leaching with HCl and NaOCl followed by filtration and precipitation with sodium metabisulphite. The slimes precipitated are calcined and smelted The process has been applied in South Africa and Tanzania. Due to the safety hazards involved in working with acids and the miners lack of training in chemistry. Mintek insists on miners attending a training course. It is currently more suited to organised medium scale rather than artisanal and small scale mining operations.

CYNIDATION Method Equipment/ Process Principle Applicability Chemical Cyanidation Leaching with sodium Cyanide and oxygen followed by adsorption onto activated carbon, elution, electrowinning and smelting. Concentrated solution that requires further processing Cyanidation has been applied by small scale miners in Colombia, Bolivia, Brazil and Zimbabwe. The method is not fast enough for processing concentrates. It is poisonous and illegal in some countries like Ghana

HABER PROCESS Method Equipment/ Process Principle Applicability Haber Leaching with a concentrated solution that requires further processing The leaching reagent is proprietary. For this process artisanal miners have to take their ore to processing centres where it is processed. This is not applicable to the artisanal mining environment as: too costly and too complex for individuals or small groups uses a proprietary chemical thus locking the miners into a foreign third party supplier has major issues of trust and keeping track of an individual’s ore

DIRECT SMELTING Method Equipment/ Process Principle Applicability Chemical Direct Smelting Melting black sand concentrates to produce pure gold Smelting is applied in most small scale centres and miners are familiar with the method as it is being used for purifying sponge gold. It has been developed, tested and commercialised in Ghana. It can be used for all types of ores and comparatively cheaper than amalgamation.

CRITERIA OF SUITATBLE ALTERNATIVE FOR GALAMSEYERS Effective Easy - requires no special equipment Quick Cheap Suitable for processing small batches of concentrate Visible - the miners can see their products throughout the whole process Locally available

CHOICE OF DIRECT SMELTING Fulfils all main criteria Uses non-toxic, cheap chemicals: borax, sodium carbonate, silica sand

SMELTING Smelting is a high-temperature melting process used to recover metals from ores and concentrates Fluxes are added to the concentrate to assist melting and react with impurities so that the metal separates out The final products are pure metal and a glassy slag containing the unwanted components

SMELTING VS AMALGAMATION Smelting gave 99.9% recovery In the lab amalgamation gave around 97% recovery In the field amalgamation gave around 88% recovery

MIXING CHARGE AND FEEDING CRUCIBLE

ALTERNATIVE FUELS LPG 38 38

FURNACES 39 39

GAS FURNACE 40 40

GAS FURNACE 41 41

DIMENSIONS OF GAS FURNACES ITEM DIMENSIONS Small Size (1) Large Size (4) Height 280 mm External Diameter 240 mm 405 mm Internal diameter 170 mm 375 mm Thickness of insulation 30 mm 60 mm Thickness of metal shell 50 m 50 mm Length of LPG inlet pipe 190 mm Air slot length 95 mm Air slot width 10 mm Number of air slots 3 42 42

GAS FURNACE 43 43

INLET PIPE SUB-ASSEMBLY 44 44

TOP COVER SUB-ASSEMBLY 45 45

CASING SUB-ASSEMBLY 46 46

CHUTE SUB-ASSEMBLY 47 47

COST ELEMENTS OF LARGE SIZE GAS FURNACE SN Item Quantity Unit Cost (GH¢) Total Cost (GH¢) 1 Casing 290.00 2 Lining 120.00 3 Ring 5.00 4 Clips 0.10 0.20 5 Hose (4 m) 6.00 6 Valve 3.00 7 Regulator 20.00 8 Hood 30.00 9 Miscellaneous 5.80   Total 480.00 48 48

COST ELEMENTS OF SMALL SIZE GAS FURNACE SN Item Quantity Unit Cost (GH¢) Total Cost (GH¢) 1 Casing 220.00 2 Lining 90.00 3 Ring 5.00 4 Clips 0.10 0.20 5 Hose (4 m) 6.00 6 Valve 3.00 7 Regulator 20.00 8 Hood 30.00 9 Miscellaneous 5.80   Total 380.00 49 49

COST OF KIT WITH LARGE SIZE GAS FURNACE SN Item Quantity Unit Cost (GH¢) Total Cost (GH¢) 1 Gas furnace (L/S) 480.00 2 Gas cylinder (15 kg) 70.00 3 Gas (15 kg) 12.00 4 Fire extinguisher (4 kg) 50.00 5 Tongs 7.00 14.00 6 Cupels 15.00 30.00 7 Hammer 3.00 8 Gloves 2.00 4.00 9 Goggles 10 Spoons 0.20 0.40 11 Weighing scale 80.00 12 Crucibles 100 40.00 13 Flux reagents 200.00 14 Mixing bowl   Total 991.40 50 50

COST OF KIT WITH SMALL SIZE GAS FURNACE SN Item Quantity Unit Cost (GH¢) Total Cost (GH¢) 1 Gas furnace (S/S) 380.00 2 Gas cylinder (15 kg) 70.00 3 Gas (15 kg) 12.00 4 Fire extinguisher (4 kg) 50.00 5 Tongs 7.00 14.00 6 Cupels 15.00 30.00 7 Hammer 3.00 8 Gloves 2.00 4.00 9 Goggles 10 Spoons 0.20 0.40 11 Weighing scale 80.00 12 Crucibles 100 40.00 13 Flux reagents 200.00 14 Mixing bowl   Total 891.40 51 51

DEMONSTRATION AND TRAINING 52 52

DEMONSTRATION IN THE FIELD 53 53

POURING OF MOLTEN MATERIAL

COOLING OF MELT IN A MOULD

SEPARATION OF GOLD FROM SLAG 56 56

SEPARATION OF GOLD FROM SLAG

GOLD BEAD

COST COMPARISON AMALGAMATION DIRECT SMELTING SN Item Cost (GH¢) 1 Half teaspoon of mercury (27 g) 4.00 4 Crucibles (2 operations) 1.60 2 Heating of amalgam (charcoal) 0.50 Flux (2 x 200 g) 1.20 3 Smelting 1.50 Gas (2 x 0.75 g) Total 6.00 (US$4.14) 4.00 (US$2.76)

COST ESTIMATES for GAS KIT SN Item Quantity Unit Cost (GH¢) Total Cost (GH¢) 1 Gas furnace (S/S) 500.00 2 Gas cylinder (15 kg) 70.00 3 Gas (15 kg) 15.00 12.00 4 Fire extinguisher (4 kg) 55.00 5 Tongs 7.00 14.00 6 Cupels 80.00 160.00 7 Hammer 3.00 8 Gloves 2.00 4.00 9 Goggles 10 Spoons 0.20 0.40 11 Weighing scale 100.00 12 Crucibles 100 40.00 13 Flux reagents 200.00 14 Mixing bowl   Total 1166.40* (US$804.41)

CHALLENGES Retrieval of loan balances How is the money accruing from the sale of the kits to be used? Formation and sustenance of Small Scale Miners’ Associations Sustenance of the Mercury Abatement Programme (accessibility & affordability) Further follow-up to sustain the momentum of the use of the technology. 61 61

THE WAY FORWARD - GHANA Ensure that the kits are readily available and accessible virtually at the door steps of the ssm; Monies accruing from the sale of the kits should serve as revolving fund; Outstanding loan balances should be retrieved by the respective District Offices of the MC; 62 62

THE WAY FORWARD - GHANA CONT’D Encourage the formation and strengthening of the SSM Associations Monitoring and follow-up should be continued for at least two (2) years; Use of the direct smelting method should be made a condition for the acquisition of license where amalgamation is used 63 63

THE WAY FORWARD - GLOBAL To achieve this feat it is recommended that the: ACP country should provide a budget or secure donor funds to launch the project possibly using the Ghana Project as model (at least €200,000.00); ACP country should organise a Management Unit (Ministry of Mines, University, NGOs, etc) to manage the project; ACP country should recruit local consultants with experience in artisanal and small scale mining of gold to undertake the project

THE WAY FORWARD – GLOBAL CONT’D Menart Geoventures Ltd, University of Mines and Technology, Tarkwa – Ghana, could be contracted to provide fabrication plans and a complete kit; Menart Geoventures Ltd, University of Mines and Technology, Tarkwa - Ghana may be contacted to provide high level consultants to supervise the project.

ACKNOWLEDGEMENT MINISTRY OF FINANCE & ECONOMIC PLANNING, GHANA EUROPEAN UNION MINERALS COMMISSION, GHANA PROJECT MANAGEMENT UNIT, GHANA BRITISH GEOLOGICAL SURVEY UNIVERSITY OF MINES & TECHNOLOGY, TARKWA (UMaT), GHANA ACP GROUP 66 66

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