The results of studies on the processing of gibbsite-kaolinite bauxite are presented. The developed technology includes preliminary chemical activation and thermal transformation during enrichment to obtain a concentrate suitable for processing by the Bayer method. As a result of the chemical activation of gibbsite-kaolinite bauxite in a solution of sodium bicarbonate, a change in the phase composition occurs, which made it possible to improve the results of gravity enrichment with the production of a coarse-grained gibbsite fraction. The transformation of bauxite in the temperature range of 900–1000 °C is explained by the decomposition reactions of siderite, gibbsite, kaolinite, calcite, dolomite and sodium ferro-sulfide oxide, as well as the formation of sodium aluminosilicate, hematite, quartz and the chemically stable phase of corundum. The optimum firing temperature of bauxite is 950 °C, after which, as a result of alkaline treatment during chemical enrichment, the extraction of SiO₂ into solution was 74.9%. A silicon modulus of enriched bauxite 10.9 units was obtained. As a result of the autoclave leaching of gibbsite-kaolinite bauxite after a two-stage enrichment, the maximum extraction of alumina into solution was 87.4%. The yield of red mud during the processing of bauxite enriched and calcined at 950 °C was 37.62%. During the autoclave leaching of bauxite without enrichment, the yield of red mud was 71%.

A technology for the hydrochemical processing of the kaolinite fraction of bauxite has been developed, and it involves preliminary chemical activation in a sodium bicarbonate solution and alkaline leaching in a recycled high-modulus solution with the addition of an active form of calcium oxide. Chemical activation allows for the transformation of the difficult-to-explore kaolinite phase to form easily soluble phases of dawsonite, sodium hydroaluminosilicate and bemite. An active, finely dispersed form of calcium oxide was obtained as a result of CaO quenching in Na₂SO₄ solution at elevated temperature and pressure. Using a central composite design (CCD) via response surface methodology (RSM), the technological leaching mode was achieved. The influence on the leaching process was studied by adjusting the CaO/SiO₂ ratio, temperature, alkaline solution concentration and duration. It was found that the determining factors are the concentration of the leaching solution and the temperature. At a stable CaO/SiO₂ ratio, a combination of these two factors determines the duration of the process to achieve the predicted degree of recovery. The results of experiments carried out using the developed model of the leaching process confirmed the validity of the calculated indicators, with an error of 2.01%. In an optimal technological mode at a Na₂O leaching solution concentration of 260 g/L, a temperature of 260 °C, a CaO/SiO₂ ratio of 1.5 and a leaching time of 5 h, the extraction of Al₂O₃ into the solution was 89.7%, which is close to the value of 87.9% predicted by the model.

The known methods of processing low-quality bauxite have a number of disadvantages that make it difficult or impossible to use them in the conditions of production of JSC "Aluminum of Kazakhstan", therefore, it is necessary to effectively develop a technology for preliminary enrichment. Enrichment of low-quality bauxites is possible by separating the clayey - high-siliceous and coarse-crystalline fractions. Electron-microscopic analysis of the original bauxite showed that the coarse-crystalline fraction is tightly pressed by the fine one. The total silicon modulus of the sample is 2.49. The silicon modulus of the fine fraction is 2.19, and that of the coarse fraction is 3.89. When enriching bauxite, as a result of the separation of fines, it is possible to increase the silicon modulus. After the chemical activation of bauxite in a sodium bicarbonate solution, the finely dispersed fraction is effectively separated from the coarse one and the phase composition changes - the calcium silicate phase disappears and the calcite phase is formed. With an increase in the activation temperature, the content of kaolinite and siderite decreases, and the content of quartz and hematite increases. Studies have shown that at temperatures of chemical activation of 120 ° C, duration of more than 120 minutes and 200 ° C, duration of more than 40 minutes, a dawsonite phase is formed in bauxite, which densifies the mineral structure. When determining the optimal regime for carrying out chemical activation, it is necessary to take into account the negative possibility of dawsonite formation.

The Donskoy Mining and Concentration Complex slime tailings concentration studies were conducted. By means of 0.2+0.071 mm slime size fraction concentration on concentrating table in open cycle, chromite concentrate with 48.8 % Cr2O3 mass fraction, yield being 29.42 %, was produced. Chromium oxide losses in tailings were 18.62 %, with 6.5 % Cr2O3 mass fraction. By means of –0.071+0 mm slime size fraction concentration on Knelson centrifugal separator in open cycle, chromite concentrate with 42.8 % Cr2O3 mass fraction, yield being 48.5 %, was produced. Chromium oxide losses in centrifugal separator tailings were 19.16 %, with 15.75 % Cr2O3 mass fraction. By means of gravity concentration circuit, total chromite concentrate, containing 43.58 % Cr2O3, was produced. Total concentrate yield was 37.0 %, with Cr2O3 recovery into concentrate — 62.45 %. Chromium total losses in tailings and in +0.2 mm size fraction will amount to 24.98 %, with its mass fraction of ~12.0 %. A technology of slime tailings activation in soda solution containing 120 g NaHCO3 per 1 dm3, at temperature +120 °С and duration of 60 min, prior to gravity concentration, resulting in slime phase composition change, has been developed. Slimes concentration on concentrating table and centrifugal separator, following preliminary activation in soda solution, permitted to produce joined salable concentrate with 51.3 % Cr2O3 mass fraction, which is 8.42 % higher, if compared to processing without activation.

When processing low-quality gibbsite–kaolinite bauxites, technologies that involve different methods of mechanical and chemical enrichment with the separation of a difficult-to-utilize fine kaolinite fraction for disposal are used. Before production, problems related to waste storage and disposal arise. To solve the problem of utilization, it is necessary to develop an effective technology for the selective processing of the kaolinite fraction. The efficiency of the technology will depend on the quality of pretreatment of raw materials prior to processing for Al₂O₃ extraction. Preliminary preparation of kaolinite fraction is associated with the maximum removal of excess silica during chemical enrichment by treatment with an alkaline solution. The presence of silica reduces the quality of final alumina products and requires a large consumption of reagents during the desiliconization of aluminate solutions. During the chemical enrichment of kaolinite fraction in alkaline solution, a serious problem of the co-dissolution of Al₂O₃ with silica arises. The solution to this problem can be the transformation of phase composition with the transformation of kaolin into a chemically resistant compound corundum, which will create conditions for the selective removal of silica. Kazakhstan’s alumina refinery, Pavlodar Aluminum Smelter, processes low-quality gibbsite–kaolinite bauxite from the Krasnogorsk deposit. To improve the quality of bauxite, preliminary gravity enrichment is carried out to separate the kaolinite fraction to a quantity greater than 50%. The purpose of this work was to study the possibility of the selective processing of the kaolinite fraction via various techniques, including preliminary thermal transformation, through sintering, chemical enrichment, autoclave leaching in a circulating aluminate solution, and low-temperature desiliconization, to obtain a solution for decomposition. As a result of this study, the possibility of obtaining a corundum phase after sintering at a temperature of 900–1000 °C was established, which made it possible to obtain 58.8% chemical enrichment through the extraction of SiO₂ into solution. Further use of the enriched kaolinite fraction in autoclave leaching in a circulating aluminate solution with low-temperature desiliconization made it possible to obtain an aluminate solution with a caustic modulus of 1.65–1.7, which is suitable for decomposition.

In order to provide ferroalloy production with high-quality raw materials, the need to develop technologies for processing of low-grade manganese and ferromanganese ores is becoming increasingly important. In view of the change in the quality characteristics of ores, the decrease in manganese content and the ability to beneficiation by traditional methods, it is necessary to consider new approaches and technological solutions. The article presents data from a study on the beneficiation of refractory iron-manganese ore from the Zhomart deposit. The mineralogy, physical and mechanical properties, and granulometric composition of the ore were determined. The results of a study on gravitational beneficiation using a laboratory pulsator with a pneumatic drive and a laboratory 2-chamber diaphragm jigging machine and magnetic beneficiation of ore with a high-intensity magnetic field are presented. Iron-containing concentrate (Fe-45% and Mn-6.5% is mainly represented by hematite mixed with non-metallic minerals quartz and calcite) and iron-manganese concentrate (Mn-21.7% and Fe-21.1% in the form of hematite, Brownite and pyrolusite, also mixed with quartz and calcite). The concentrates are not suitable for smelting manganese-containing ferroalloys but can be used in the process of electrothermal beneficiation with selective carbothermal reduction of iron in an ore-thermal furnace. The smelting products can be manganese cast iron and iron-free, low-phosphorus limiting manganese slag with a high ratio of manganese to iron.