Research on Carbon Thermal Reduction Modification and the Self-Pulverization Mechanism of Blast Furnace Dust Synergizing with Basic Oxygen Furnace Slag

Abstract

This study employed a "reduction + modification" treatment technique for steel slag, using the carbon (C) and SiO₂ from blast furnace dust as reductants and modifiers to perform carbothermal reduction modification on converter hot-sprayed slag. The process simultaneously achieved slag self-pulverization and iron recovery. Chemical composition and phase analysis of the slag and dust were initially conducted to identify their primary phases. Subsequently, thermodynamic simulations, experimental studies, and multi-method analyses systematically investigated the effects of the dust-to-slag ratio, carbothermal reduction temperature, and holding time on the product pulverization rate. The results indicated that increasing the dust-to-slag ratio and reduction temperature enhanced pulverization, achieving up to 86.84% under optimal conditions. However, insufficient reduction at lower ratios resulted in negligible self-pulverization. Orthogonal experiments optimized processing parameters, revealing that pulverized products primarily comprised Ca₂Al₂SiO₇, RO, and γ-Ca₂SiO₄, which were devoid of phosphorus. Non-pulverized residues predominantly contained nCa₂SiO₄·Ca₃(PO₄)₂. Furthermore, thermally stable Mn₂P facilitated high-temperature phosphorus reduction from nCa₂SiO₄·Ca₃(PO₄)₂, promoting slag self-pulverization.