Investigation of the effect of hot lime process on cyanide leach

In this study, the sample was taken from Gümüştaş Mining Tepeköy Process Plant. Hot lime and leaching tests were applied with different amount of cyanide and CaO in order to dissolve precious materials such as gold and silver in plumbo jarosite ores. Au grade was 8,63 g/t and Ag grade was 191,4 g/t in the samples. All tests were performed twice and the arithmetic mean of the results were accepted as final results. The temperature was 90 oC for all the tests. Firstly, -75 µm ground material was leached with 500 mg/L, 1000 mg/L, 1500 mg/L, 2000 mg/L and 3000 mg/L NaCN concentrations in stable CaO treatment condition (40 kg/t). After tests completed, the best recovery was detected as 1000 mg/L NaCN concentration. Then, sample was leached without CaO pretreatment. Au and Ag extractions in cyanide leaching were calculated as 63.65% and 61.67% respectively. In the next tests, -75 µm samples were leached with different lime amounts by 40 kg/ton, 70 kg/ton, 100 kg/ton, 150 kg/ton, 250 kg/ton CaO. The optimum amounts of lime feeding determined as 250 kg/ton. Later, samples were divided into 4 different size fraction as 75 µm (d80), 44 µm (d80), 30 µm (d80) and 30 µm (d100). -30 µm (d100) samples were dissolved with 1000 mg/L NaCN, 250 kg/ton CaO at 90 oC. This test was named as optimum test condition. 91% Au and 82% Ag dissolution recovery were obtained by optimum test parameters.