Preparation and performance of ceramic filter material by recovered silicon dioxide as major leached component from red mud

In this study, a new ceramic filter material was prepared by recovering red mud from red mud at atmospheric pressure. The primary objective of this research was to investigate the effects of SiO2 quantity and sintering temperature (ST) on the porosity, stability, microstructure, and performance of the resulting materials. The results demonstrated that after a two-step leaching process with 3 M HCl and 90% sulfuric acid, the recovery of SiO2 from red mud exceeded 80%. The SiO2 extracted from red mud was used as the main material and mixed with other materials including Na-bentonite, limestone and pulverized coal at a ratio of 65:25:8:2, resulting in a ceramic filter material with favorable chemical stability, high strength, and nontoxicity. The enhanced surface activity of the material can be attributed to the abundant Si-OH groups, which enable it suitable for the ammonia nitrogen removal from drinking water. Overall, silicon dioxide extracted from red mud will help solve the stockpile and pollution problems of it in China.