This work presents the results of optimizing the physicochemical properties of composite briquettes based on microsilica 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 strength of the finished briquettes was studied. The methods of obtaining and testing the briquettes, their composition, and the briquetting and drying process are 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 not only improves the quality of the final product but also addresses environmental issues related to the disposal of microsilica, reducing its accumulation and minimizing its impact on the environment.

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.

Currently, enterprises producing crystalline silicon are facing the formation and accumulation of large volumes of microsilica, a technogenic dusty waste formed during the melting of silicon alloys. Due to its chemical composition, this waste can be a significant raw material for metallurgical production. Therefore, this study is aimed to solve the problem of recycling microsilica. For these studies, a technology for the combined briquetting of microsilica and a carbonaceous reducing agent was developed for the production of a pilot batch of briquettes. This paper presents the results obtained from the process of testing the melting of crystalline (technical) silicon from briquetted monocharge obtained from microsilica. The tests were conducted under large-scale laboratory conditions on a 200 kVA ore-thermal furnace, where 30, 50, and 100% replacements of the traditional charge mixture with briquettes were tested. The results of this study showed that briquettes in the melting process of technical silicon can be successfully used in the range of 0 to 50%. The use of briquettes can significantly improve the technological indicators. The maximum extraction of silicon (approximately 83%) was achieved at 30% replacement. The technical and economic indicators of the process also improved. In particular, an increase in productivity was observed in comparison with tests on a traditional charge.

A major problem of the technological production process of the metallurgical-grade silicon is formation of a large amount of microsilica. However, this material can be a significant source of raw materials for its own production. Hence, this study is aimed to solve the problem of micro-silica utilization, i.e. the technogenic dust-like waste generated during the melting of the technical-grade silicon. Within this study, the technology of the joint briquetting of microsilica was investigated with the carbonaceous reducing agents, i.e. by obtaining of mono-charge and by melting of the technical-grade silicon from the obtained mono-charge in the 200kVA ore-thermal furnace. Results of the study show that the briquettes in the melting process of the technical-grade silicon can be used in the range from 0 to 50%. The using of briquettes may significantly improve the technological parameters. When briquetted charge is applied only, the technological parameters will deteriorate significantly. The material balance of silicon melting showed the recovery rates of the main elements (Si, Al, Ca and Fe). It recorded a decrease in content of aluminum from 1.9-2.1% to 0.5-0.7%, calcium from 0.2-0.3% to 0.07-0.1% and titanium from 0.2-0.23% to 0.11-0.13% during the transition to briquetted monocharge. Phosphorus content increased from 0.004-0.005 to 0.011-0.013%.

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.