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MERCURY POLLUTION ABATEMENT PROJECT

MERCURY POLLUTION ABATEMENT PROJECT. MENART GEOVENTURES ENT. LTD P. O. BOX 237 TARKWA GHANA. PRESENTATION AT BRUSSELS BY PROF. S. AL-HASSAN. 13 TH - 15 TH DECEMBER, 2010. OUTLINE OF PRESENTATION. Objective ASSM Mining methods in Ghana Available alternatives

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MERCURY POLLUTION ABATEMENT PROJECT

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  1. 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

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

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

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

  5. GEOLOGICAL MAP OF GHANA SHOWING ROCK FORMATIONS THAT CONTAIN GOLD

  6. LOCATION OF SMALL-SCALE MINNG DISTRICT CENTRES, GHANA

  7. ASSM GOLD & DIAMOND PRODUCTION Total Ghana Production SSM Contribution 1989 Gold 2% Diamonds 40% 2001 Gold 6% Diamonds 95% 2007 Gold 12% Diamonds 98% Source:Minerals Commission, Ghana

  8. 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)

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

  10. CONCENTRATION (DRY AREA) Washing Winnowing

  11. MINING OF ALLUVIAL DEPOSITS

  12. MINING HARD ROCK (REEFS)

  13. SSM DREDGING IN GHANA (SUCTION)

  14. MILLING (HARD ROCK)

  15. 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

  16. SLUICING

  17. PANNING

  18. GOLD CONCENTRATE IN A PAN

  19. AMALGAMATION

  20. SQUEEZING EXCESS MERCURY FROM AMALGAM

  21. FIREPLACE FOR BURNING AMALGAM

  22. SPONGE GOLD

  23. GATHER AND SELL

  24. OPEN HEATTH FOR SMELTING GOLD

  25. 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

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

  27. SLUICING

  28. COAL-GOLD AGGLOMERATION

  29. Igoli Process

  30. CYNIDATION

  31. HABER PROCESS

  32. DIRECT SMELTING

  33. 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

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

  35. 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

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

  37. MIXING CHARGE AND FEEDING CRUCIBLE

  38. ALTERNATIVE FUELSLPG 38

  39. FURNACES 39

  40. GAS FURNACE 40

  41. GAS FURNACE 41

  42. DIMENSIONS OF GAS FURNACES 42

  43. GAS FURNACE 43

  44. INLET PIPE SUB-ASSEMBLY 44

  45. TOP COVER SUB-ASSEMBLY 45

  46. CASING SUB-ASSEMBLY 46

  47. CHUTE SUB-ASSEMBLY 47

  48. COST ELEMENTS OF LARGE SIZE GAS FURNACE 48

  49. COST ELEMENTS OF SMALL SIZE GAS FURNACE 49

  50. COST OF KIT WITH LARGE SIZE GAS FURNACE 50

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