Transbaikal State University, Chita, Russia:

L. V. Shumilova, Professor, Doctor of Engineering Sciences, shumilovalv@mail.ru

The article gives examination data on material constitution of pebble size particles and fines in stockpiles of placer gold ore mining. It is found that waste material content of valuable component makes 0.35 g/m3, free gold is not visible, 88.46 % of encapsulated ultra-fine noble metal is distributed in the size grades of -0.2+0.1, -0.1+0.05, –0.05 mm and 55.6 % is concentrated in magnetite. Developed based on the previous positive results of laboratory tests, the gravity concentration–hydrometallurgical processing flow chart for gold-bearing waste material includes one sluice-box operation and two-stage leaching of noble metal with active multi-agent chemical compounds produced by electrochemical and photochemical synthesis. Semicommercial tests on extraction of metal from magnetite gravity concentrate with gold content of 0.75 g/m³ have been carried out. The semicommercial test plant includes technological circuits of gravity, first-stage leaching with highly active hypochloric acid, second-stage leaching with cyanides, carbon adsorption, desorption and regeneration, electrolysis and melting of cathode deposit. Refined and approved in the course of the tests, the technical regimes and production data of hydrometallurgical recovery of metal confirm the efficiency of the proposed non-conventional approach to dissociation of gold-bearing minerals owing to generation of macro-, micro- and nano-pores. The absolute gold recovery from the initial material reaches 95 %. The semicommercial tests confirm producibility of base bullion with total mass fraction of 10 % and above in accordance with technical requirements TU 117-2-7-75. The designed continuous production line ensures all-year operation, including conditions of low temperatures. The outcome of the new process solution is the enhancement of the efficiency and rate of gold recovery from mining waste as well as the sound utilization of natural resources.

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