Prolonged development of ore deposits, ore beneficiation and metallurgical smelting of concentrates result in the accumulation of wastes, forming large-scale dumps and sludge ponds negatively affecting the environment and human health. The creation and introduction of industrial waste treatment technologies will make it possible to dispose of them with the production of valuable commercial products and improve the environmental situation. In a research article on chemical beneficiation with the subsequent gravitational beneficiation of chrome-containing slurry tailings of Donskoy Ore-Mining and Beneficiation Plant (DOMBP), which processes chrome ore of the Kempirsay deposit in the Republic of Kazakhstan, Aktobe region, having considerable stocks of such waste is presented. The chromium-containing slurry tailings were heat-treated at 1100 °C, sintered with ammonium sulfate, water and sulfuric acid in a defined ratio at 300 °C, and then the resulting sinter was leached with water at 90 °C. The cake was washed to separate the liquid part from the solid part. The solid precipitate is the chromium-containing cake, which is upgraded by gravity concentration to a grade concentrate for ferroalloy production. When the solution is evaporated, magnesium sulfate with ammonium sulfate forms the Tutton’s salt ammoshenite. High-throughput chromium oxide extraction of 93.9% was achieved as a result of the research, and three products were obtained: (1) standard chromium concentrate with 49.48% Cr₂O₃ content, (2) ammoshenite used as a nitrogen–magnesium fertilizer and (3) forsterite, which is concentrated in gravity concentration tailings and can be used in the production of refractory minerals.

This study presents the results of the enlarged laboratory research on the melting of calcined composite pellets for ferrochrome obtained from fine-dispersed conditioned chrome concentrate containing 50.3% Cr₂O₃. This is a product of the gravitational beneficiation of waste sludge tailings from the Dubersay tailings dump at the Donskoy Mining and Processing Plant (DMPP) of JSC “TNC Kazchrome”. The composition of the charge for obtaining composite pellets consisted of 88.5% of chrome concentrate, 3% of mineral part of refined ferrochrome slag (RFC), 4% of ferruginous diatomite, 3% of coke and 1.5% of liquid glass. The initial charge was pelletized on a laboratory pelletizer to a size of 6–10 mm, dried at room temperature for 24 h and fired at 1200 °C for 60 min at a heating rate of 15 deg/min. On the basis of the developed composite annealed pellets, studies on the production of high-carbon ferrochrome at different melting temperatures were carried out. The results showed that with an increase in temperature from 1750 to 1850 °C, the iron–chromium phase in the composition of the alloy increases from 45.2 to 50.1%, the chromium carbide phase decreases from 23.7 to 11.3% and the chromium–iron phase increases from 7 to 11.2%. The carbon content in the alloys at temperatures from 1750 to 1850 °C varies from 7.2 to 8.94%, respectively. The maximum chromium content of the alloy is 64.82% with a melting point of 1850 °C; this alloy can be classified as FeCr60C90LP grade ferrochrome according to the international Chinese standard, which has no more than 0.03% phosphorus and no more than 0.1% sulfur.

The flocculation of flotation concentrates in the presence of anionic polyelectrolytes was studied, while filtration of lead concentrate with a density of 45%, a positive effect was obtained with the consumption of the flocculant carboxymethyl cellulose (CMC) 28-85 g / t. In the case of filtration of zinc concentrates with a density of 41%, good results were obtained at a flow rate of 44-104 g / t. The flotation kinetics regularities in the presence of individual non-ionic polymers (PEG, PEO and PVA) are studied using the example of flotation waste suspension. With increasing electrolyte concentration in the system, the flocculation rate in comparison with the coagulation rate first increases, then decreases more and more. Experiments have been conducted on the filtration of lead and zinc concentrates on a laboratory vacuum filter in the presence of mixtures of nonionic polymers (PEO, PEG and PVA) and anionic flocculants (PAA, PMAC and CMC). In the presence of PEO + CMC mixtures, the maximum sedimentation rate of the lead concentrate was 2.6 cm / sec, and in the case of zinc concentrate -2.1 cm / sec. When mixtures of PEO + PAA and PEO + PMAC were used, the maximum sedimentation rate of lead and zinc concentrates ranged from 1.4 to 1.8 cm / sec. When the lead concentrate was filtered with a density of 48%, a positive effect was obtained with the consumption of the flocculant PEO + CMC 22-91 g / t. In the case of filtration of zinc concentrates with a density of 42%, good results were obtained at a flow rate of 31-112 g / t.