Abstract
A series of experimental intermittent bottle roll tests was conducted on various content of gold and silver on oxide and sulfide ores at PT Bumi Suksesindo. The ores content variation that was used are high gold with low silver content, low gold with high silver content, both high gold and high silver content, and both low gold and low silver content for each oxide and sulfide ores. The intermittent bottle roll test was carried out at 33% of solids with the initial concentration of NaCN in the solution is 1,000 ppm and maintained at a concentration of 750 ppm. The sample size fraction that was used is -25.0 +0.6 mm with a P80 of 12.5 mm. The pregnant leach solutions were analyzed for the gold and silver concentrations using AAS (Atomic Absorption Spectrophotometer) and also analyzed for the NaCN concentrations by the titration method using AgNO3 (Silver Nitrate). Besides, the remaining solids (tail) were also analyzed for the gold and silver concentrations by the acid digest method (using aqua regia) to determine the metal extraction. The results showed that the highest gold extraction was obtained on the high gold and low silver content of 79.0% for the oxide ore samples and 82.8% for the sulfide ore samples. The gold extraction on the oxide ores tends to be lower than the sulfide ores, and the gold extraction is dependent on the total amount of gold and silver in the ores. The greater the total amount of gold and silver on the ores, the lower the gold extraction obtained for both oxide and sulfide ores. The average NaCN consumption for the sulfide ores is 1.33 kg/t, which almost three times more than the NaCN consumption for the oxide ores, which are on average of 0.46 kg/t.
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