Abstract
Heap leaching with a cyanide solution is used for processing low-grade ores; however, owing to the chemical, mineralogical, and physical characteristics of ores and their particle size distribution, extraction efficiencies are often low. This study investigated the effects of sodium acetate addition on gold extraction from Akshoky deposit ores under laboratory and semi-pilot laboratory test conditions. The gold-bearing ore used in this study had average gold and silver contents of 1.32 and 3.27 g/t, respectively. The chemical composition of the ore was as follows (wt%): copper: 0.0185, nickel: 0.0090, cobalt: 0.0025, zinc: 0.0470, lead: 0.0095, total iron: 4.10, calcium oxide: 3.08, magnesium oxide: 1.10, sodium oxide: 1.40, potassium oxide: 0.82, silicon oxide: 64.22, aluminum oxide: 13.37, arsenic: 0.023, antimony: 0.0024, total sulfur: 0.24, sulfate sulfur: 0.040, and sulfide sulfur: 0.20. Gold in the ore occurs in different forms: free/native form grains (82 %), covered with films (3.28 %), associated with sulfides (6.56 %), and in fine-grained form (8.20 %). Laboratory tests showed that gold dissolution from ground ore by a cyanide solution without sodium acetate addition was 83.08 %. However, with sodium acetate addition (0.1; 0.5; 1.0 kg/t), it increased to 84.38-86.61 %. Semi-pilot laboratory tests under heap-leaching conditions confirmed the positive effects of sodium acetate. The increase in gold extraction was 7.6 % (62.9 %) compared with that in the experiments without reagent addition (55.30 %).