Zhadiger Sadyk

This study investigates the possibility of producing a complex W–Mo–Cr-containing alloy via metallothermic reduction of oxide concentrates in the presence of direct reduced iron (DRI) in an induction furnace under atmospheric conditions. A complex FeAlSiCa alloy was used as a reductant due to its high exothermicity and combined reducing potential. Thermodynamic analysis showed that the reduction of WO₃ and MoO₃ is more favorable compared to Cr₂O₃, which is reflected in the temperature profiles of the process. Experimental results confirmed that the addition of FeAlSiCa leads to intensive exothermic reactions and promotes melt formation. The estimated apparent recovery of W and Mo reached up to ~99%, while Cr estimated apparent recovery remained lower (up to ~70%) due to its higher thermodynamic stability and kinetic limitations. Microstructural analysis revealed a heterogeneous structure consisting of an Fe-based matrix and W–Mo-rich phases, including characteristic “fishbone” morphologies. An increase in reductant amount led to higher Si content in the alloy, indicating the need for composition optimization. The results demonstrate the feasibility of direct complex alloying as an alternative to conventional ferroalloy-based methods and highlight the potential for developing resource-efficient and low-carbon metallurgical technologies.

This study investigates the production of high-carbon ferrochrome (HCFeCr) using pre-reduced chromite pellets. Chromite ore from the Kempirsai deposit, semicoke as a reducing agent, and activated bentonite as a binder were used for pellet preparation. Pellets with a size of 12–14 mm were produced and subjected to reduction roasting at 1400 °C for 1–3 h. The results showed that increasing the roasting time promoted chromite reduction and increased the chromium metallization degree. After 3 h of roasting, the chromium metallization degree reached 43.93%. SEM analysis confirmed the formation of metallized chromium-containing phases and a porous structure favorable for subsequent smelting. Smelting experiments were carried out in a 0.1 MVA ore-thermal furnace using pre-reduced pellets. Stable furnace operation, satisfactory slag fluidity, and effective separation of metal and slag were observed. The obtained high-carbon ferrochrome contained 68.92 wt.% Cr, 1.54 wt.% Si, and 7.11 wt.% C. Chromium recovery into the alloy reached 92.17%, while the slag contained 2.14 wt.% Cr₂O₃. The specific electric energy consumption during experimental smelting was 4648.1 kWh/t of ferrochrome. Recalculation to industrial conditions showed an expected energy consumption of 3132.76 kWh/t, confirming the potential of pre-reduced chromite pellets for energy-efficient ferrochrome production.

This study investigates the agglomeration of chromium-containing dust from ferroalloy production using rigid vacuum extrusion. Direct utilization of fine technogenic materials in submerged arc furnaces is limited due to poor gas permeability, increased dust generation, and unstable smelting conditions. The aim of this work was to compare bentonite and polymer binders in brex production and evaluate their metallurgical applicability. Chromium-containing dust from the gas-cleaning system of the Aktobe Ferroalloy Plant (TNC Kazchrome JSC, ERG) was characterized using chemical analysis and SEM/EDS methods. The material exhibited a heterogeneous structure composed mainly of chromium-containing spinel, silicate, and oxide phases. Pilot-industrial extrusion tests were performed using J.C. Steele & Sons equipment with bentonite (10 wt.%) and polymer binder TD 021.005.BS (2.5 wt.%). The polymer binder provided improved brex geometry and significantly higher mechanical strength, achieving impact strength values up to 89.5% after curing. SEM/EDS analysis of the obtained brexes confirmed the formation of a dense agglomerated structure with uniform distribution of chromium-containing phases. Thermodynamic modeling using FactSage 8.4 showed that brex addition does not significantly affect slag composition, phase equilibria, or metal quality during high-carbon ferrochrome smelting. The results demonstrate the feasibility of polymer binders for efficient recycling of chromium-containing technogenic wastes by rigid vacuum extrusion.

The study investigates the technology of direct Cr alloying of steel in an induction furnace using Cr-containing oxide raw materials and an FeAlSiCa metallothermic reducing agent under atmospheric conditions. The experimental design included four charge variants: scrap-based, DRI-based, A-series (50% scrap/50% DRI), and B-series (75% scrap/25% DRI). For A-series and B-series, the FeAlSiCa content was varied from the baseline value to reduced levels of −10% and −20%. The results demonstrate that Cr recovery strongly depends on the metallic component of the charge. The highest Cr recovery (up to 83%) was consistently achieved for the DRI-based charge, while mixed charges showed intermediate values depending on the DRI fraction and reducer amount. Reduction in FeAlSiCa content led to a decrease in Si transfer to steel, but was accompanied by lower Cr recovery. The produced steels were characterized by a uniform distribution of alloying elements, low impurity levels (S, P < 0.03%), and the formation of a dense, non-disintegrating slag. The results confirm that direct Cr alloying in an induction furnace can be effectively implemented under atmospheric conditions without vacuum or protective gas atmosphere, while the presence of DRI plays a key role in enhancing Cr assimilation.

This study investigates the feasibility of producing an Fe-Cr-Mn complex alloy through the recycling of technogenic wastes from metallurgical operations. The feed materials comprised chromium-bearing dust collected from the gas-cleaning system of high-carbon ferrochrome production, iron–manganese ore fines (<10 mm) from the Tur deposit (Kazakhstan), and coal sludge used as a carbonaceous reducing agent. Thermodynamic modeling of the carbothermic reduction of Cr and Mn oxides and the predicted distribution of components among the metal, slag, and gas phases were performed using the HSC Chemistry 10 software package over a high-temperature range. At 1800 °C, the calculated chemical composition of the target alloy was as follows (wt.%): Cr-35.84, Mn-24.47, Si-16.25, Fe-22.63, and C-0.82. To validate the modeling results, experimental smelting trials were carried out in a 100 kVA electric arc furnace, producing both metallic and slag phases. The average composition of the metal phase was (wt.%): Cr-37.17, Mn-14.46, Si-11.48, Fe-33.23, C-3.48, P-0.15, and S-0.021. The experimental results indicate the formation of a Cr-Mn alloy with elevated Cr and Fe contents and a noticeable C level, confirming the carbothermic nature of the reduction reactions. The composition and microstructural features of the smelting products were examined by scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM/EDS). The findings demonstrate that the combined use of technogenic raw materials and a carbonaceous reductant enables the production of a Cr- and Mn-enriched metallic phase under satisfactory slag-forming conditions. Overall, the results confirm the potential of a resource-saving approach for valorizing fine technogenic wastes in the production of complex ferroalloys and for improving the recovery of target elements through optimization of the charge composition and smelting parameters.

This study investigates the exothermic effects and viscosity properties of multicomponent oxide melts during the high-temperature reduction of low-grade Cr–Mn ores. Unlike previous thermodynamic-focused research, this work provides experimental evidence of transient exothermic responses and correlates them with melt properties. High-temperature experiments identified pronounced exothermic effects in the 800–1600 °C range. Phase analysis (XRD, SEM–EDS) confirmed effective Cr and Mn reduction into Fe–Cr–Mn–Si alloys with minimal residual oxides in the slag. Effective viscosity, measured via the electrovibrational method at 1400–1650 °C, decreased monotonically with temperature. Arrhenius analysis was applied to determine activation energies and crystallization onset temperatures (T_cr). The results indicate low viscosity and high thermal stability of the slags, ensuring efficient metal–slag separation. These findings confirm the technological feasibility of using low-grade ores for Fe–Cr–Mn alloy production and provide a basis for optimizing industrial smelting.

This study presents the results of an investigation into the carbothermic synthesis of silicon carbide (SiC) from microsilica and petroleum coke. The research combines thermodynamic modeling with experimental validation conducted in an ore-thermal furnace. Thermodynamic calculations were performed using the HSC Chemistry 10 software package to evaluate the influence of temperature and the SiO₂/C ratio on phase formation and the conditions of SiC synthesis. The results show that the synthesis process exhibits a strong dependence on temperature and is largely governed by the carbon balance of the charge. At an SiO₂/C ratio of 1, the system is carbon-rich, which promotes effective reduction of silicon dioxide. However, at elevated temperatures, these conditions intensify gas-phase reactions and lead to increased silicon losses. The most favorable conditions for silicon carbide formation were achieved at an SiO₂/C ratio of 1.5, which is close to the stoichiometric value. This conclusion is confirmed by the maximum degree of SiC recovery obtained under experimental conditions. In contrast, at an SiO₂/C ratio of 2, carbon deficiency results in incomplete reduction in SiO₂ and a lower yield of the target product. The phase composition of the synthesized samples was analyzed by X-ray diffraction, revealing β-SiC as the dominant crystalline phase. The morphology and structure of the materials were examined using scanning electron microscopy, which confirmed the formation of SiC particles and aggregates with characteristic features. A comparison between calculated and experimental results demonstrates that thermodynamic modeling adequately describes the main trends of the process and can be effectively applied to optimize SiC synthesis conditions during the processing of technogenic silica-containing waste.

This study investigates the thermodynamic and experimental aspects of producing a chromium–manganese ligature under high-temperature smelting conditions using low-grade iron–manganese ore and ferrosilicochrome (FeSiCr) dust as both a reducing agent and a chromium source. Thermodynamic modeling of the multicomponent Fe–Cr–Mn–Si–Al–Ca–Mg–O system was carried out using the HSC Chemistry 10 and FactSage 8.4 software packages to substantiate the temperature regime, reducing agent consumption, and conditions for the formation of a stable metal–slag system. The calculations indicated that efficient reduction of manganese oxides and formation of the metallic phase are achieved at a smelting temperature of 1600 °C with a reducing agent consumption of approximately 50 kg. Experimental smelting trials conducted in a laboratory Tammann furnace under the calculated parameters confirmed the validity of the thermodynamic predictions and demonstrated the feasibility of obtaining a concentrated chromium–manganese ligature. The resulting metallic product exhibited a high total content of alloying elements and had the following chemical composition (wt.%): Fe 35.41, Cr 41.10, Mn 8.15, and Si 4.31. SEM–EDS microstructural analysis revealed a uniform distribution of chromium and manganese within the metallic matrix, indicating stable reduction behavior and favorable melt crystallization conditions. The obtained results demonstrate the effectiveness of an integrated thermodynamic–experimental approach for producing chromium–manganese ligatures from low-grade mineral raw materials and industrial by-products and confirm the potential applicability of the proposed process for complex steel alloying.

The article presents the results of a study on the production of a complex chromium–manganese–silicon-containing ferroalloy in a large-scale laboratory ore-thermal furnace using man-made waste—chromium-containing aspiration dust obtained during smelting of high-carbon ferrochrome, fines (−5 mm) of iron–manganese ore currently stored in landfills, and finely dispersed coal sludge formed during enrichment. A single-stage technology for the production of a new complex chromium–manganese–silicon-containing ferroalloy by carbothermal reduction is proposed. A metallurgical assessment of the initial charge materials was carried out by the X-ray diffraction (XRD) phase analysis, and metal samples of the obtained ferroalloy were studied by scanning electron microscopy (SEM) in combination with energy dispersive spectroscopy (EDS). The resulting ferroalloy has a complex microstructure with a predominance of carbide and intermetallic phases. A high degree of extraction of chromium (up to 80%), manganese (up to 75%), and silicon (up to 35%) was recorded. The average chemical composition of the obtained ferroalloy, wt.%: Cr—37.41; Mn—17.31; Si—11.84; C—3.81; P—0.14; S—0.02. The slag formed during the smelting of the ferroalloy has satisfactory technological properties: it is characterized by good fluidity, and it actively exits the furnace by gravity. Entanglement of metal kings in the slag is not observed. The results obtained confirm the technological feasibility of the utilization of technogenic raw materials for the production of complex ferroalloys of the FeCrMnSi type.

This study investigates the production of chromium–manganese ligature by a metallothermic process using complex silicon–aluminum reducing agents. Low-grade chromium and iron–manganese ores from the Kempirsai and Kerege-Tas deposits in Kazakhstan were used as raw materials, while the reducing agents included alumosilicomanganese alloy (AlSiMn) and ferrosilicoaluminum (FeSiAl). Thermodynamic calculations were performed with HSC Chemistry 10 at 1400–1800 °C and reducing agent dosages of 10–100 kg per 100 kg of ore charge. Crucible smelting experiments were then carried out in a Tamman furnace, followed by large-scale laboratory trials in a 100 kVA refining electric furnace to verify reproducibility, with a total of 14 runs. The chemical composition of the ligatures varied depending on the reductant: with AlSiMn the alloy contained Fe—23.14%, Cr—53.74%, Mn—20.03%, and Si—3.06%; with FeSiAl, it contained Fe—42.01%, Cr—25.74%, Mn—27.15%, and Si—5.05%; and with FeSiCr dust, it contained Fe—34.45%, Cr—21.45%, Mn—39.82%, and Si—4.24%. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses confirmed the presence of α-(Fe,Cr,Mn), FeSi, and Cr₅Si₃ phases. The results demonstrate the efficiency of complex silicon–aluminum reducing agents and the ability to regulate the composition of chromium–manganese ligatures by the selected reductant.