North Caucasian Mining and Metallurgical Institute (State Technological University), Vladikavkaz, Russia:
I. G. Trotsenko, Associate Professor of the Department of Metallurgy of Non-Ferrous Metals, e-mail: itrocenko@mail.ru
T. E. Gerasimenko, Head of the Department of Intellectual Property, e-mail: gerasimenko_74@mail.ru
S. I. Evdokimov, Associate Professor of the Department of Mineral Processing, e-mail: eva-ser@mail.ru

Small mining enterprises are striving to create on-site facilities for the processing of gold-containing concentrates with the production of the final highly liquid commodity products in the form of Dore alloy ingots. Complex hardware design and high cost of metallurgical methods for processing of gold-containing concentrates do not allow to recommend them for such enterprises. A competitive technology for preparing graded gold for smelting is a magneto-liquid separation with preliminary separation of non-ferrous sulfides and iron by vacuum-thermal sublimation (sublimation). An experimental sample of mini concentrate processing mill (CPM) of “Priisk”, which circuit diagram of apparatus includes equipments sequentially installed for separating the gold: vacuum-thermal opening reactor → centrifugal disintegrator → magnetic separator → magnetic-liquid separator. At a temperature of 400–450 ^oC, arsenopyrite passes into low-toxic sublimates, and at 530 ^oC the antimonite is almost completely condensed in the form of antimony sulphide. Full sublimation of galena is achieved at a temperature of 800 ^oC, and sphalerite at 1000 ^oC. Lead is mainly sublimed in sulphide form, and zinc is in the form of metal vapors. In the non-volatile residue, the sublimation of pyrite at 460–550 ^oC contains 3–5% of the undecomposed mineral, the rest is diagnosed as magnetic pyrrhotite. To decrease the specific sublimation rate, sulphides can be arranged in a series: galena, antimonite, arsenopyrite, sphalerite. When testing the mini-CPM “Priisk” at a temperature of 600 ^оС corresponding to the working zone of a vacuum thermal reactor and a pressure of 7·10^–4 Pa, the weight of gold-containing concentrates was reduced approximately by 2 times. The loss of gold during the magnetic-liquid separation of the concentrates was no more than 1.0%.
Specific capital costs and operating costs for finishing the concentrates according to the developed technology enabled to conduct the process more economically. The article was prepared with the support of the Grant Agreement No. 14.577.21.0142 (RFMEFI57714X0142).

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