The article presents the results of obtaining a composite material by sintering nickel-containing raw materials mixed with carbon-containing materials, namely using coke and semi-coke. The sintering process was performed at a charge layer height of 240 mm and the temperature of the lower layer was T = 1200 °C. The results of the sieve analysis showed (a fraction of 10 mm) that the yield of a suitable composite material using coke was 68.3% and with semi-coke 67.0%. The average nickel and chromium content in the composite materials was 1.42% and 3.07%, accordingly. As a result of determining the strength characteristics of the obtained composite materials with various reducing agents by dropping from a height of 2 m onto a steel pallet, it was found that the obtained composite materials have high mechanical properties in terms of strength of 81% and 89.2%. The results of the elemental composition at the studied points and the thermal analysis of the studied composite material are presented. The mineralogical composition of the composite material is presented in the form of serpentine and nontronite, and the empty rock is made of quartz and talc. The activation energy of thermal analysis by the method of non-isothermal kinetics were calculated. The results of experiments on the production of composite materials from nickel-containing raw materials will be recommended for obtaining the optimal composition of composite materials at the stage of pilot tests and industrial development of the developed technology for processing nickel ores of the Republic of Kazakhstan. For the processing of nickel-poor nickel ores, it is of great importance to obtain optimal technological and technical and economic indicators that ensure low cost of nickel in the resulting product.

This paper presents the results of optimizing the physicochemical properties of microsilica-based composite briquettes for metallurgical-grade silicon production. Microsilica, a waste product of silicon production, contains a sufficiently high amount of silicon dioxide (96–97%). This fact makes microsilica a promising composite material for metallurgical processing. However, its granulometric composition limits its direct use. The method of briquetting on an industrial briquetting press was used. The influence of the granulometric composition of the composite mixture on the heat tolerance and reactivity of the finished briquettes was studied. The methods of obtaining and testing the briquettes, their composition, and the briquetting and drying process were described. The obtained briquettes were tested for the smelting of metallurgical silicon. The silicon recovery rate in the metal with the standard charge was 71%, while the recovery rate with the briquetted monocharge was 85%. The results of silicon smelting from the briquettes demonstrated the high quality of the obtained metal, corresponding to the standards of metallurgical-grade silicon. The implementation of these technologies improves the quality of the finished product and addresses environmental issues related to the disposal of microsilica, reducing its accumulation and minimizing its impact on the environment.

This study investigates the thermodynamic and kinetic features of chromium reduction from chromium ore using complex Fe–Si–Cr and Al–Si–Cr alloys as reducing agents for the refined ferrochrome production. The thermodynamic probability of Cr₂O₃ reduction by silicon and aluminum was evaluated using thermodynamic equilibrium calculations based on reference thermodynamic data, including determination of the standard Gibbs free energy change over the studied temperature range. The results showed that both reduction routes are thermodynamically feasible, while aluminum exhibits a higher affinity for oxygen and a greater reducing capacity. The thermal behavior of chromium ore and its mixtures with Fe–Si–Cr and Al–Si–Cr alloys was studied by differential thermal and thermogravimetric analysis. The use of Al–Si–Cr, especially in briquetted form, was found to shift several thermal transformation stages to lower temperatures and to reduce the apparent activation energy of the high-temperature interaction stages compared with Fe–Si–Cr-containing mixtures. The obtained results indicate that Al–Si–Cr alloy is a promising complex reductant for intensifying chromium recovery and improving process conditions in refined ferrochrome production.

Magnetization roasting followed by magnetic separation can upgrade ferruginous manganese raw materials, but its efficiency depends on the iron phase state after roasting. This study clarified the phase state and distribution of iron in magnetic and non-magnetic products obtained from ferruginous manganese ore and concentrate after magnetization roasting and dry magnetic separation. The materials were roasted at 600–650 °C using Shubarkol coal as a solid reducing agent and then separated at a magnetic field strength of 1.2 kOe. Chemical analysis, X-ray diffraction, and Mössbauer spectroscopy were used to relate separation results to iron phase states. The Mn/Fe ratio in the non-magnetic products increased from 3.92 to 10.87 for the ore and from 2.98 to 23.99 for the concentrate, while 76.25% and 88.26% of iron were transferred to the corresponding magnetic fractions. Mössbauer spectroscopy showed that magnetite-type spinel components, including Fe₃O₄ and substituted (Fe_1−xM_x)₃O₄, were mainly associated with the magnetic products. Hematite-like and paramagnetic Fe³⁺/Fe²⁺ components were also detected, indicating incomplete conversion of iron-bearing phases into magnetite-type spinels. The Mössbauer-area-weighted fraction of iron in magnetite-type spinel phases was 76.5% for the ore and 64.36% for the concentrate. These results explain the different separation behavior after roasting–magnetic treatment.

The beneficiation of ferruginous manganese ores is limited by the intimate intergrowth of manganese-, iron-, and silicate-bearing phases. This study evaluated coal-based magnetizing roasting followed by dry magnetic separation in an externally heated chamber furnace with a charge capacity of up to 100 kg. A 0–5 mm ore fraction with an initial Mn/Fe ratio of 2.9 was roasted with Shubarkol coal. The best separation was obtained at an actual ore–coal bed temperature of 550–600 °C and an ore-to-coal mass ratio of 1:0.4. Relative to the magnetic-separation feed, 80.0–83.4% of Fe was recovered in the magnetic fraction, while 69.9–72.6% of Mn remained in the non-magnetic product. Its Fe content decreased to 3.2–3.5%, increasing the Mn/Fe ratio to 7.30–7.84. X-ray diffraction showed preferential concentration of magnetite and jacobsite in the magnetic fraction, whereas hausmannite and braunite were concentrated mainly in the non-magnetic fraction together with the gangue phases. Multipoint measurements also demonstrated a substantial difference between the combustion-zone and actual bed temperatures. The results demonstrate that controlled low-temperature roasting can generate sufficient magnetic contrast for selective iron removal from ferruginous manganese ore.

The article presents the results of calculating the thermodynamic functions (enthalpy, entropy and Gibbs energy) of chromium reduction reactions from its oxide with the participation of active metal reducing agents by applying the constants of substances and the values of the coefficients of the heat equation, considering the phase transformations involved in reactions such as silicon and aluminum, which occur in the production of refined ferrochrome grades. This calculation is performed by applying the substance constant to the transformed formula for calculating the dependence of the Gibbs energy on the temperature of the reactions of redox processes. As noted above, the results of this calculation are of fundamental importance in the melting processes of refined (medium- and low-carbon) ferrochrome grades with separate and joint (in the form of complex silicon and aluminum-containing alloys) using the above-mentioned elements. The calculations were carried out in the temperature range from 298 K to ~3000 K, since this interval covers the conditions of the redox processes. The range under consideration covers the entire temperature range of phase transformations of chromium ore and reducing agent (siliceous or silicon-aluminum). For these reactions, there are several temperature intervals due to the phase transformations of the initial reagents and the resulting products. After performing thermodynamic calculations, graphs of the dependence of the Gibbs energy change on temperature are constructed. Temperature intervals where phase transitions do not affect the reaction are revealed. Consequently, along with passive temperature intervals, there are active intervals in which a sharp increase in the negative value of the Gibbs energy was observed.