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.

The range of all types of ferroalloys is traditionally determined by the requirements of consumers, primarily steelmaking enterprises, as well as the technological capabilities of their pro-duction and the quality of the ore raw materials. Over the past half-century, steel production technology has undergone significant changes, including the transfer of operations for the introduction of ferroalloys for alloying, deoxidation, and refining of steel from melting units to the ladle. This necessitates the development of new ferroalloy compositions with the most favorable physicochemical characteristics for steel processing that account for the lower temperature in the ladle and the limited time for reagent interaction. One of the most widely used and important elements for steel alloying is chromium, which is utilized in the production of both structural and corrosion-resistant grades of steel. In this context, the study investigates the dependence of the physicochemical properties (density, melting temperature, and melting time in liquid steel) of alloys in the Cr–C–Si–Fe system on the chromium and silicon content. It has been demonstrated that increasing the silicon content to 10% and reducing the chromium content from 63 to 53% improves the performance characteristics of ferroalloys, including the following reductions: the crystallization onset temperature from 1620 to 1530 °C, and the density from 7540 to 6800 kg/m³. The melting time of high-carbon ferrochrome in steel depends on the Cr content: when the chromium content decreases from 63 to 45%, the melting time of the alloy decreases by 3.1 times, which is mainly due to the decrease in the temperature of the onset of crystallization of the ferroalloy from 1620 to 1570 °C. Chromium-containing ferroalloys are usually introduced into the volume of liquid steel and are slightly prone to corrosion. One of the main characteristics of ferrochrome, from the point of view of their use for alloying steel, is the time of their melting in liquid steel, which is greatly influenced by the melting temperatures of ferroalloys. The speed and degree of assimilation of alloying elements and, accordingly, the duration of extra-furnace steel treatment depend on the melting time of ferroalloys in molten steel, which significantly affects the technical and economic indicators of production. It is not possible to obtain standard grades of ferrochrome containing 63% or more Cr from low-grade chromium ores using existing process flow charts, since these ores are distinguished not only by a low chromium content, but also by a high iron content. High values of the Fe/Cr ratio determine low chromium concentrations in the resulting ferroalloys.

Along with the growth in the production of metallurgical grade silicon and high-silicon ferrous alloys, there is a significant increase in the formation of microsilica, which is an ultra-fine technogenic waste. The direct application of microsilica in ore-thermal furnaces is hindered by low bulk density, poor gas permeability, and high dusting. This paper explores the thermophysical and microstructure properties of briquettes based on microsilica, which includes various types of carbonaceous reducing agents such as semi-coke and coal. For manufacturing, the liquid glass was used as the inorganic binder for the preparation of microsilica briquettes. The best variants were chosen based on strength tests carried out during preliminary studies. In the laboratory tests, the stability of the briquettes at elevated temperatures was evaluated. Samples were heated to 1000–1500 °C and subjected to impact testing. Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS) was used to investigate the microstructure and local elemental distribution. It was revealed that the calcinated briquettes of the microsilica–semi-coke mixture have better thermal stability compared to the samples with coal and withstand the temperature range up to 1500 °C. The microstructure of the briquette from the microsilica-semi-coke mixture is characterized by the formation of a more uniform silicate matrix with the presence of a homogeneously distributed carbonaceous component. Coal-based samples show higher heterogeneity and porosity. Therefore, it can be stated that the selection of carbonaceous reductants is one of the key factors influencing the thermal stability of microsilica briquettes.

This study evaluates coke for iron ore sintering manufactured from Ekibastuz coal fines (fraction 0–3 mm), spent anode material (SAM) from aluminum electrolysis, and coal tar pitch. Laboratory coking was performed at 1000 °C (60 min hold), followed by sintering trials using coke containing 10 wt% and 20 wt% SAM. Microstructural (SEM/EDS) and spectral data indicate an optimal SAM range of 10–20 wt%: higher additions (≥30 wt%) lead to structural degradation of coke, accompanied by reduced mechanical integrity. The produced coke shows C = 85%, S = 0.9–1.1%, ash ≈ 19%, volatiles = 1.5–2.5%, and moisture (Wr) ≤ 1%, which is acceptable for sintering use. In sintering tests, the yield of usable sinter reached 72.4% (10 wt% SAM) and 73.5% (20 wt% SAM); impact strength was 83% and 78%, respectively. XRF of sinter showed Fe_total > 51%, CaO ≈ 5.5–6.8%, SiO₂ ≈ 6.6–7.2%, and S = 0.40–0.45%, meeting technological requirements for blast-furnace practice. Overall, using spent anode material within 10–20 wt% increases fixed-carbon content, enables valorization of aluminum industry waste, and delivers coke for agglomeration performance without compromising key chemical or mechanical indices.

This study explores the fabrication and characterization of hybrid aluminum matrix composites reinforced with boron carbide (B₄C) and microsilica, produced via ultrasonically assisted stir casting followed by T6 heat treatment. Pure aluminum was selected as the base matrix to evaluate the combined effects of B₄C and microsilica reinforcements. Microstructural analyses showed that ultrasonic treatment effectively dispersed nanoparticles, reduced agglomeration, and enhanced particle–matrix interfacial bonding. T6 heat treatment further refined the grain structure through Zener pinning and promoted the formation of reaction layers at particle interfaces. Mechanical testing revealed that Al/B₄C composites provided the highest strength and hardness, while Al/microsilica systems retained superior ductility. The hybrid Al/B₄C/microsilica composites demonstrated a balanced combination of yield strength (38.6 MPa), ultimate tensile strength (82.6 MPa), and elongation (35.2%), confirming a synergistic strengthening–toughening effect. These results highlight the potential of Al/B₄C/microsilica hybrid reinforcements to optimize the trade-off between strength and ductility in aluminum-based composites.