Development of Gold Extraction Technology from Refractory Gold Concentrates Based on Fine Grinding

The problem of in-site treatment of refractory gold and silver flotation concentrates is urgent in Russia at present, because the cost of concentrate treatment at copper smelters raises the cost of the recovered gold up to 30%. Sorption leaching with ultrafine pre-grinding of concentrates to a particle size of 0.010-0.020 mm has emerged as one of the perspective methods of handling this problem. A peculiarity of the devised technology is that ultrafine grinding is performed in standard ball mills loaded with different particle size material, thus providing a maximum contact surface. Typical low-coned hydrocyclones with 75 mm, 50 mm, and 35 mm diameters assembled in a multi-cyclone battery are used as classifying equipment. The proposed grinding scheme produces a final product of 98-99% minus 0.020 mm.

Pilot plant tests on pyrite and arsenopyrite concentrates from various deposits of Zabaikalie were carried out. The refractory nature of these concentrates is due to the presence of finely disseminated gold. Gold extraction from these concentrates, ground to 98-99% minus 0.074 mm in hydrometallurgical cycle does not exceed 80%. Concentrate grinding to 98-99% minus 0.020 mm enables a rise in the gold extraction in the subsequent carbon sorption cycle by 10-15% and reduces gold losses in sorption tailings by 3-5 g/t.