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On January 21, join SGS' Chris Fleming at the National CMP in Ottawa as he presents 'Development of Process Options To Treat Oxidized Mineralization Containing A Very High Concentration Of Cyanide-Soluble Copper.'


Jan 21, 2020, 13:00


Jan 21, 2020, 14:00


Ottawa, Canada


Emipa, a division of Orvana Minerals Inc., is looking at various options to process an oxide copper/gold deposit in Bolivia. Cyanidation is one option for treating this material, but a very high level of cyanide-soluble copper in the ore (6-8 kg/t) has created unique processing challenges. Cyanide consumption is 16 -18 kg/t NaCN, of which ~80% reports to the pregnant leach solution (PLS) as the copper cyanide complex. The cost of this cyanide, along with the cost of cyanide destruction to control the build up of copper in a closed system, renders the project uneconomic unless cyanide recovery can be included in the flowsheet. The SART Process converts copper cyanide to a saleable copper sulphide by-product and free cyanide for recycling to leach, and its incorporation in the flowsheet could provide an economic benefit to the project. In heap leach tests, the fast-leaching copper mineralization creates a unique free cyanide-starved chemical environment in the solution flowing through leach test columns, which has presented operational challenges such as possible CuCN precipitation in the column. The gold cyanide complex is more stable than copper cyanide, so gold (and silver) continue to leach under cyanide-starved conditions, although their rates of leaching are somewhat slower than they would be if free cyanide was available. 



By *C. Fleming1, J. MacDonald1, J. Espinoza3 and L. Melis2

1 SGS Minerals

185 Concession Street

Lakefield, ON, K0L 2H0

(*Corresponding author:

2 Empresa Minera Paititi S.A. Emipa,

Barrio Equipetrol Calle 6 Este No. 7,

Santa Cruz de la Sierra,


3 Melis Engineering Ltd.,

2366 Ave. C North, Suite 100,

Saskatoon, SK, S7L 5X5



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SGS is the world’s leading inspection, verification, testing and certification company. SGS is recognized as the global benchmark for quality and integrity. With more than 97,000 employees, SGS operates a network of over 2,600 offices and laboratories around the world.