Utilization of bayer red mud derived from bauxite for belite-ferroaluminate cement production

Abstract

Bayer red mud (BRM) is a kind of industrial solid waste characterized by huge volume and high alkalinity. Its disposal generates serious environmental pollution and occupies a large number of farmland. The utilization and recycling of BRM is currently a crucial issue and needs to be addressed as soon as possible. The chemical composition of BRM is similar to cement clinker. In this study, the feasibility of preparing Belite-ferroaluminate clinker (BFAC) with different BRM was explored. The physical properties, mechanics performance, radioactivity levels and trace harmful metals leaching were measured. XRD, BEI and EDS were used to characterize the mineral formation, and SEM is used to reveal the solidified mechanism of trace harmful metal. The results show that the preparation of BFAC using a certain amount of BRM was feasible. The formed phases in clin-kers mainly included C4A3Š,C2S and C4AF. The flexural strength and compres-sive strength of BFAC at 3 days increased whereas 28 and 90 days decreased with the increase of BRM due to the formation of higher C4AF and lower C2S. The formation of large amounts of Al2O3·3H2O gel and Fe2O3·3H2O gel in hydration products enhanced the adsorption capability to heavy metals and other ions. The trace harmful metal concentration in the leaching solution was much less than the upper limits. The radioactivity level of leaching solution was close to natural radioactive background. BRM is safe as raw material of BFAC.