Effect of Dispersant on the Dispersibility of CaO–Al2O3-Based Mold Powder Slurry

The fast hydration rate of aluminate makes the slurry of CaO–Al2O3-based mold flux coagulates fast, which hinders the production and large-scale application in steel plants. This study selected four dispersants and investigated their mechanism and influence on the dispersibility of CaO–Al2O3-based mold powder slurry. Main results showed that the stability of CaO–Al2O3-based mold powder slurry was poorer than CaO–SiO2-based mold powder slurry. The addition of non-ionic dispersant, OP-10 or glycerol, could make the viscosity of the CaO–Al2O3-based slurry become larger, and the macromolecule dispersant, Poly Vinyl Pyrrolidone, resulted in unstable variation of the viscosity of the mold powder slurry. The anionic dispersant, tannic acid, performed well, as it was able to release negative charges covering the powder particles, and the electrostatic repulsion made the aggregation among particles difficult to occur. The 5 wt% addition of tannic acid was found to effectively improve the dispersion of the CaO–Al2O3-based slurry.