Numerical Simulation of Red Mud Blended Raw Materials in a Precalciner

Abstract The cement industry is a major contributor to global carbon emissions and pollutants, so reducing emissions while utilizing industrial wastes is critical for its green development. Red mud, a solid waste byproduct of alumina smelting with main components like SiO2, Al2O3, and CaO, can partially replace limestone as a raw material in cement production. TG-DSC thermal analysis clarified red mud’s threestage weight loss characteristic during calcination (total weight loss rate of 22.11%), and orthogonal experiments identified calcination temperature as the core factor for its CaO content, with the optimal calcination pretreatment process confirmed (0.075~0.09 mm particle size, 1373 K, 1 h residence time, CaO content up to 21.1%). Based on the results,this study uses ANSYS Fluent to simulate a TTF-type precalciner, establishing a validated multi-physical field model (all relative errors <5%) to explore red mud blending ratios of 0%, 2.5%, 5%, 7.5% and 10%. Results show red mud slightly alters the internal temperature field, reduces raw meal decomposition rate (all values within the 85%~95% industrial range), and effectively decreases CO2 and NOx emissions. A 5% ratio is recommended, which balances waste utilization, decomposition efficiency, and emission reduction, providing solid technical support for red mud’s large-scale use in cement production.