Evaluation of the Cyanidation Leaching of Gold in a Waste Rock Ore

Samples of the waste rock obtained from Marofengin South Africa ground ۶۰, ۷۰ and ۸۰% passing ۷۵µm were leached with cyanide in bottle roll tests. The results obtained showed that the percentage gold dissolution depends more on the ore size consists than on the cyanide concentration with the highest average dissolution rates of ۸۸.۷۵, ۹۴.۳۴ and ۹۵.۹۰% found at ۶۰۰, ۵۰۰ and ۵۰۰ ppm, for ۶۰, ۷۰ and ۸۰% passing sizes, respectively. It was also noted that the lowest average percents cyanide consumption of ۶۲.۹۱, ۶۱.۷۳ and ۵۸.۵۶ at ۶۰, ۷۰ and ۸۰% passing ۷۵ µm were obtained at the ۵۰۰ ppm cyanide concentrations. It was further observed that a clear pattern of increasing residual lime content was only observed at the ۷۰% grind size, with the least lime content of ۱۵۰.۳۷ ppm at ۵۰۰ ppm cyanide concentration being higher than the least lime contents for the ۶۰ and ۸۰% grind sizes. The results obtained thus suggest the ۷۰% grind passing ۷۵ µm ore with the gold dissolution percentage very close to the conventional ۸۰% passing size at the lowest cyanide consumption of ۵۰۰ ppm, much lower daily power consumption of about ۹۲۵ kWh and high residual lime content that indicated the minimization of cyanide loss as hydrogen cyanide,a good choice for the leaching of the waste rock.

کلیدواژه ها:

Waste rock ، Ground ، dissolution ، Cyanide ، lime ، pH ، Power consumption