North Caucasian Institute of Mining and Metallurgy (State Technological University), Vladikavkaz, Russia:

S. I. Evdokimov, Associate Professor, Candidate of Engineering Sciences, eva-ser@mail.ru
T. E. Gerasimenko, Head of the Intellectual Property Department, Candidate of Engineering Sciences

Gravitational methods are insufficiently effective in gold recovery of rebellious morphotype, i.e. small and fine particles, as well as gold leaves and scales. Such difficult-to-recover gold is the cause of highmetal losses in tailings. Such industrial waste contains 7–12% of total gold resources and reserves in Russia. Attraction of investors for the development of man-made placers is constrained by the lack of cost-effective technologies for their processing. The use of complex flowsheets and expensive high-tech equipment (for example, based on creation of an intense centrifugal field) for the extraction of fine and very find gold in processing by gravity is less effective than separation of minerals based on their wettability, i.e. flotation, when the ‘buoyancy’ of gold promotes an increase in the recov ery of rebellious gold species. The scientific novelty of the work lies in the fact that gold content in bulk flotation is increased owing to mixing rough concentrate extracted from ½ part of the initial feed (I stream) and the other ½ part of the initial feed (II stream). The transition from the vertical configuration of the beneficiation cascade (when middlings of a subsequent circuit go to the previous circuit) to the horizontal ‘jet’ configuration provides the increased gold recovery. At the semi-commercial scale of placer gold mining, the advantage of mining waste processing by combination of gravity and flotation technology over processing solely by gravity has been proven. The addition of the gravity technology to flotation of gold particles increases the annual gold production by ~ 29% rel. owing to the extra recovery of gold species persistent to gravitational methods. The integrated processing technology by gravity-and-flotation is economically justified: the added value of the marketable products provides elevation of the net present value and the investment profitability index at the reduced payback period.

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