Presentation is loading. Please wait.

Presentation is loading. Please wait.

MERCURY POLLUTION ABATEMENT PROJECT 1 MENART GEOVENTURES ENT. LTD P. O. BOX 237 TARKWA GHANA 13 TH - 15 TH DECEMBER, 2010 PRESENTATION AT BRUSSELS BY PROF.

Similar presentations


Presentation on theme: "MERCURY POLLUTION ABATEMENT PROJECT 1 MENART GEOVENTURES ENT. LTD P. O. BOX 237 TARKWA GHANA 13 TH - 15 TH DECEMBER, 2010 PRESENTATION AT BRUSSELS BY PROF."— Presentation transcript:

1 MERCURY POLLUTION ABATEMENT PROJECT 1 MENART GEOVENTURES ENT. LTD P. O. BOX 237 TARKWA GHANA 13 TH - 15 TH DECEMBER, 2010 PRESENTATION AT BRUSSELS BY PROF. S. AL-HASSAN

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 km 2 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 District Centres Location Region Tarkwa, Bibiani, & Asankragua Western Assin Fosu, & Dunkwa- on-Offin Central Akim Oda Eastern Bolgatanga Upper East

7 ASSM GOLD & DIAMOND PRODUCTIONYear Gold Prodn (oz) Diamond Prodn (carats) ,457,152 2,457, , , ,381,345 2,381,345 1,090,072 1,090, ,236,833 2,236, , , ,274,627 2,274, , , ,031,971 2,031, , , ,138,944 2,138,944 1,065,923 1,065, ,342,722 2,342, , , ,628,290 2,628, , , Gold 2% Diamonds 40% 2001 Gold 6% Diamonds 95% 2007 Gold 12% Diamonds 98% Total Ghana Production 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) Winnowing Washing

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 leaching Direct Smelting

27 SLUICING Method Equipment/ Process PrincipleApplicability PhysicalSluiceGravity concentratio n 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.

28 COAL-GOLD AGGLOMERATION Method Equipment/ Process PrincipleApplicability 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.

29 Igoli Process Method Equipment/ Process PrincipleApplicability ChemicalIGoli processLeaching 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.

30 CYNIDATION Method Equipment/ Process PrincipleApplicability ChemicalCyanidationLeaching 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

31 HABER PROCESS Method Equipment/ Process PrincipleApplicability HaberLeaching 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 individuals ore

32 DIRECT SMELTING Method Equipment/ Process PrincipleApplicability ChemicalDirect SmeltingMelting 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.

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 FUELS LPG 38

39 FURNACES 39

40 GAS FURNACE 40

41 GAS FURNACE 41

42 DIMENSIONS OF GAS FURNACES ITEM DIMENSIONS Small Size (1)Large Size (4) Height280 mm External Diameter240 mm405 mm Internal diameter170 mm375 mm Thickness of insulation30 mm60 mm Thickness of metal shell50 m50 mm Length of LPG inlet pipe190 mm Air slot length95 mm Air slot width10 mm Number of air slots33 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 SNItemQuantityUnit Cost (GH¢)Total Cost (GH¢) 1Casing Lining Ring Clips Hose (4 m) Valve Regulator Hood Miscellaneous5.80 Total

49 COST ELEMENTS OF SMALL SIZE GAS FURNACE SNItemQuantityUnit Cost (GH¢)Total Cost (GH¢) 1Casing Lining Ring Clips Hose (4 m) Valve Regulator Hood Miscellaneous5.80 Total

50 COST OF KIT WITH LARGE SIZE GAS FURNACE SNItemQuantityUnit Cost (GH¢)Total Cost (GH¢) 1Gas furnace (L/S) Gas cylinder (15 kg) Gas (15 kg) Fire extinguisher (4 kg) Tongs Cupels Hammer Gloves Goggles Spoons Weighing scale Crucibles Flux reagents Mixing bowl Total

51 COST OF KIT WITH SMALL SIZE GAS FURNACE SNItemQuantityUnit Cost (GH¢)Total Cost (GH¢) 1Gas furnace (S/S) Gas cylinder (15 kg) Gas (15 kg) Fire extinguisher (4 kg) Tongs Cupels Hammer Gloves Goggles Spoons Weighing scale Crucibles Flux reagents Mixing bowl Total

52 DEMONSTRATION AND TRAINING 52

53 DEMONSTRATION IN THE FIELD 53

54 POURING OF MOLTEN MATERIAL

55 COOLING OF MELT IN A MOULD

56 56 SEPARATION OF GOLD FROM SLAG

57 Gold

58 GOLD BEAD

59 COST COMPARISON AMALGAMATIONDIRECT SMELTING SNItemCost (GH¢)SNItemCost (GH¢) 1Half teaspoon of mercury (27 g) Crucibles (2 operations) Heating of amalgam (charcoal) 0.502Flux (2 x 200 g)1.20 3Smelting1.503Gas (2 x 0.75 g)1.20 Total6.00 (US$4.14)Total4.00 (US$2.76)

60 COST ESTIMATES for GAS KIT SNItemQuantity Unit Cost (GH ¢ ) Total Cost (GH ¢ ) 1Gas furnace (S/S) Gas cylinder (15 kg) Gas (15 kg) Fire extinguisher (4 kg) Tongs Cupels Hammer Gloves Goggles Spoons Weighing scale Crucibles Flux reagents Mixing bowl Total * (US$804.41)

61 CHALLENGES 1.Retrieval of loan balances 2.How is the money accruing from the sale of the kits to be used? 3.Formation and sustenance of Small Scale Miners Associations 4.Sustenance of the Mercury Abatement Programme (accessibility & affordability) 5.Further follow-up to sustain the momentum of the use of the technology. 61

62 THE WAY FORWARD - GHANA 1.Ensure that the kits are readily available and accessible virtually at the door steps of the ssm; 2.Monies accruing from the sale of the kits should serve as revolving fund; 3.Outstanding loan balances should be retrieved by the respective District Offices of the MC; 62

63 THE WAY FORWARD - GHANA CONTD 4.Encourage the formation and strengthening of the SSM Associations 5.Monitoring and follow-up should be continued for at least two (2) years; 6.Use of the direct smelting method should be made a condition for the acquisition of license where amalgamation is used 63

64 THE WAY FORWARD - GLOBAL To achieve this feat it is recommended that the: 1.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); 2.ACP country should organise a Management Unit (Ministry of Mines, University, NGOs, etc) to manage the project; 3.ACP country should recruit local consultants with experience in artisanal and small scale mining of gold to undertake the project

65 THE WAY FORWARD – GLOBAL CONTD 4.Menart Geoventures Ltd, University of Mines and Technology, Tarkwa – Ghana, could be contracted to provide fabrication plans and a complete kit; 5.Menart Geoventures Ltd, University of Mines and Technology, Tarkwa - Ghana may be contacted to provide high level consultants to supervise the project.

66 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

67 RIDE A CROCODILE AT PAGA, GHANA


Download ppt "MERCURY POLLUTION ABATEMENT PROJECT 1 MENART GEOVENTURES ENT. LTD P. O. BOX 237 TARKWA GHANA 13 TH - 15 TH DECEMBER, 2010 PRESENTATION AT BRUSSELS BY PROF."

Similar presentations


Ads by Google