To evaluate the phase and structural components of grinding media made of cast iron with a high content of copper and silicon obtained by extracting iron from copper-smelting slags, phase equilibria in the iron – carbon system were calculated with the addition of copper and silicon in various concentrations. The calculation was carried out using the ThermoCalc software package with construction of phase diagrams by the Calphad method. At the same time, temperatures of the beginning of phase transformations were estimated taking into account the presence of all thermodynamically possible phases in the system at various combinations of copper and silicon concentrations.

Reduction of iron in high-phosphorus oolitic ore from the Lisakovsk deposit using solid carbon, carbon monoxide, and hydrogen. An X-ray phase analysis was used to determine the phase composition of the samples after reduction roasting. When reduced with carbon monoxide or hydrogen, α-iron appears in the samples, while phosphorus remains in the form of iron, calcium, and aluminum phosphates. After roasting with solid carbon, phosphorus is reduced from iron and calcium phosphates and migrates into the metal but remains in aluminum phosphate. A micro X-ray spectral analysis showed that at a temperature of 1000 °C and a holding time of 5 h, during reduction with solid carbon, the phosphorus content in the metallic phase reaches up to 7.1 at. %. When reduced with carbon monoxide under the same conditions, the metallic phase contains only iron, and phosphorus is found only in the oxide phase. When reduced with hydrogen at 800 °C, phosphorus is almost absent in the metallic phase, but at 900 °C, phosphorus is reduced and its content in the metallic phase reaches 2.1 at. %.

This study investigates the behavior of phosphorus during high-temperature smelting of hydrogen-reduced high-phosphorus oolitic iron ore from the Lisakovsk deposit. The preliminary reduction was carried out at temperatures ranging from 600 to 900 °C using hydrogen, aiming to selectively reduce iron to the metallic phase while retaining phosphorus in the oxide form. The resulting reduced products were subjected to wet magnetic separation and liquid-phase separation. It was found that neither method provides effective separation of phosphorus from iron: phosphorus partially enters the magnetic fraction and, during smelting, transfers into the metallic phase. To confirm the mechanism of phosphate reduction by metallic iron, a control experiment was conducted, in which a mixture of reduced iron and raw ore was smelted at 1650 °C. Microstructural and elemental analyses confirmed the redistribution of phosphorus into the metallic phase. These findings indicate that effective separation of iron and phosphorus cannot be achieved by reduction roasting alone and highlight the need for further studies on slag formation conditions and phase separation kinetics.

Thermodynamic modeling combined with experimental reduction tests was conducted to investigate the selective reduction behavior of iron-manganese ore using hydrogen gas at 800–900 °C. The results reveal that hydrogen reduction at a flow rate of 0.5 L/min promotes the stepwise transformation of iron oxides (Fe₂O₃ → Fe₃O₄ → FeO → Fe), accompanied by the decomposition of the intermediate spinel phase Fe2MnO4, resulting in the formation of metallic iron. In contrast, the reduction of MnO to metallic manganese is thermodynamically unfavorable (ΔG > 0), limiting the extent of manganese reduction. Experimental findings confirm the formation of metallic iron inclusions enriched in Fe, while manganese predominantly remains in the form of MnO and silicate-associated oxides. X-ray diffraction analysis of reduced samples shows a decrease in Fe₃O₄ and Fe₂MnO₄ phases with increasing reduction degree and indicates the growth of metallic Fe particles with rising temperature. These results demonstrate that hydrogen enables controlled and selective reduction of iron with minimal manganese conversion, providing a promising route for subsequent efficient magnetic separation of metallic and oxide phases following reduction roasting.

Processing of nickel ores is a key aspect of modern metallurgy due to the growing demand for nickel in stainless steel, battery production, and advanced materials. The depletion of high-grade sulfide ores has shifted attention toward oxidized (lateritic) nickel ores, which are characterized by complex mineralogy and low metal content. This study presents a comparative review of major processing technologies, including pyrometallurgical, hydrometallurgical, and hybrid approaches, with particular emphasis on their applicability to Kazakhstan’s limonitic laterites with high iron and low nickel content. The analysis shows that the most suitable processing routes for such ores include atmospheric acid leaching (AL), high-pressure acid leaching (HPAL), metallothermic reduction, and combined flowsheets integrating thermal and leaching stages. Among these, AL and hybrid approaches are identified as the most promising under resource-constrained conditions. Despite recent technological progress, challenges remain related to energy consumption, economic feasibility, and environmental impact. The study highlights the importance of developing energy-efficient and low-carbon technologies, including hydrogen-based reduction, and provides practical recommendations for selecting and adapting processing methods for Kazakhstan.