To further explore the reaction mechanisms of direct alloying using manganese ore and the factors influencing manganese ore yield in converter, this study re-established a thermodynamic reaction model for direct alloying with manganese ore by coupling the oxidation and reduction reactions of [Mn]. The model investigated the equilibrium relationships between (MnO) content in slag, (FeO) content, temperature, and manganese content under different carbon levels. Through thermodynamic calculations, it is concluded that: endpoint [C] content greater than 0.13%, (MnO) content in slag greater than 20%, (FeO) content between 9% and 15%, and endpoint temperature above 1620 °C, which can achieve [Mn] content in molten steel over 0.5%. Through hot-state experiments in a 500 kg medium-frequency induction furnace, achieving a manganese ore yield of 38.7–48.4% under laboratory experimental conditions. By using the double-slag process to improve the dephosphorization rate in the primary stage, less-slag control in the later stage and high-carbon tapping are achieved. By adding 5.5–10.5 kg/t of manganese ore during the decarburization period, a higher manganese ore yield of exceeding 50% is achieved, with carbon content at the endpoint reaching 0.16–0.22% and slag volume controlled between 40 and 60 kg/t.

This article uses a water model with a ratio of 1:5.75 to study the influence of factors such as the position and flow rate of top and bottom composite argon blowing on the mixing time of molten steel in a 300t ladle at a certain factory. Using engine oil to simulate steel slag, the mass transfer velocity of molten steel under different bottom and top blowing positions and flow rates of the ladle was compared. At the same time, numerical simulation was used to analyze the changes in the flow field of molten steel under different ladle blowing modes. The optimal ladle composite bottom argon process was proposed and industrial experiments were conducted on site. The research results show that the stirring effect of top–bottom composite argon blowing in the ladle is significantly better than that of the pure bottom blowing mode. When the top blowing gun is located 300 mm at the bottom of the ladle, the mixing time of the molten steel is shortest and the stirring efficiency is highest. The higher the insertion depth of the top blowing gun, the faster the flow rate of the molten steel, and the smaller the proportion of dead zones. Top and bottom blowing can improve the mass transfer rate between steel slag and promote the formation of refined slag. Through industrial experiments, it was found that the S content in the molten steel decreased by approximately 22.3% and the total oxygen content decreased by 25% before and after 10 min of composite argon blowing at the top and bottom of the ladle.

To optimize the hydrodynamic conditions of the converter vanadium extraction process, a three-dimensional multiphase flow model of the top-blowing system in a 200 t vanadium extraction converter was established based on computational fluid dynamics (CFD). Conventional 3-hole and “3+1”-hole (with a central nozzle) oxygen lance schemes were designed to investigate the effects of nozzle design Mach numbers and inter-nozzle flow distributions on jet characteristics, impact cavity morphology, and internal molten bath flow fields, aiming to select the optimal oxygen lance nozzle structure. The results indicate that for oxygen lances without a central nozzle, lowering the design Mach number mitigates shock wave energy dissipation and enlarges the gas–liquid reaction surface area; however, due to the lack of longitudinal penetrating force from a central jet, a large stagnation dead zone is prone to forming at the bottom. For oxygen lances with a central nozzle, the inter-nozzle flow distribution governs the impact cavity morphology and the evolution of the flow field. Excessive central flow causes the impact cavity to exhibit a “deep and narrow” profile and exacerbates surface kinetic energy dissipation, whereas insufficient central flow results in a “shallow and wide” cavity that makes it difficult to drive deep circulation. Based on a multi-objective evaluation, the “3+1” configuration adopting a 1:1 balanced flow ratio between the central nozzle and a single peripheral nozzle (Case 2#) effectively balances the allocation of jet momentum between radial expansion and longitudinal penetration, achieving synergistic optimization of the gas–liquid reaction interface expansion and deep-bath stirring, thus serving as the optimal scheme. The findings of this study provide an important theoretical reference for the engineering design and industrial trials of oxygen lance nozzles in large-tonnage vanadium extraction converters.

Smelting with a high scrap ratio in converters holds significant importance for carbon reduction and emission reduction in the iron and steel industry. Under high scrap ratio conditions, the kinetic and thermodynamic conditions of the molten bath change significantly, leading to considerable differences in the elemental reactions and slag formation patterns during the smelting process. To investigate the reaction characteristics and dephosphorization behavior of the molten bath under different scrap ratios, this study conducted thermal simulation experiments of converter smelting with four scrap ratios (20%, 30%, 40%, and 50%) using a 500 kg induction furnace. Scrap preheating and supplemental heating agents were applied as needed. Slag petrographic analysis was carried out using SEM and EDS. The experimental results indicate that with scrap ratios of 20% and 30%, the carbon–oxygen reaction and slag formation efficiency are relatively high. The dephosphorization rate in the early stage of smelting can exceed 50%, and phosphorus is effectively enriched in the CaO–SiO₂ matrix phase, with the highest phosphorus distribution ratio observed at a 30% scrap ratio. In contrast, with scrap ratios of 40% and 50%, the carbon–oxygen reaction is slower, and the dephosphorization rate in the early smelting stage is less than 10%. In the 40% scrap ratio experiment, phosphorus began to accumulate significantly in the dicalcium silicate phase during the mid-smelting stage as the basicity increased. At a 50% scrap ratio, the silicate matrix remained the dominant phase throughout all smelting stages, and no distinct phosphorus-rich phase was formed.