ULTRAFINE GRINDING EFFECT ON AUTOCLAVE OXIDATION PROCESS PERFORMANCE FOR REFRACTORY GOLD-COPPER-ARSENIC FLOTATION CONCENTRATE

The article presents the results of material composition studies of a refractory gold-copper-arsenic concentrate. The nature of gold dissemination in the mineral components of the studied flotation concentrate shows that gold is more associated with sulfides and less with iron hydroxides. The results obtained indicate that gold is predominantly small. The process flow scheme is offered for processing of the studied flotation concentrate. It includes the following operations: ultrafine grinding, autoclave oxidation, alkaline atmospheric treatment of autoclave oxidation cake with subsequent sorption cyanidation. The effect of feed size on the behavior of components in autoclave oxidation was studied. This process was investigated using a sulfuric acid solution with a concentration of 50 g/l at the L : S = 2 : 1 ratio, oxygen pressure of 0,8–1,0 MPa, and temperature of 95±10 °C. It was found that the optimal duration of autoclave oxidation is 4 h. High performance was reached when the flotation concentrate was subjected to preliminary ultrafine grinding to –0,020 mm (85 %) Alkaline atmospheric treatment of the solid cake was carried out under the following conditions: L : S = 3 : 1 ratio, CaO feed – 100 g/kg, temperature – 95 °C, duration – 2 h. Fixed residue of autoclave oxidation was subjected to CIL for 8 h at the ratio of L : S = 3 : 1, pH = 9,5÷11,0, NaCN concentration – 1 g/l, coal feed – 5 vol.%. It was found that this technology provides up to 96 % gold recovery.

gold, copper, arsenic, refractory flotation concentrates, autoclave oxidation, atmospheric alkaline treatment, cyanidation, recovery

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