Green synthesis of aluminum hydroxide from alumina–silica based solid hazardous waste

Abstract

The collaborative detoxification and extraction of valuable resources from various industrial wastes are proposed based on the composition characteristics and toxic properties of different solid/hazardous wastes such as coal gangue, aluminum dross, red mud, spent cathode carbon blocks, and carbide slag. The coupling reaction mechanism of the valuable or toxic components of aluminum, sodium, silicon, calcium, iron, fluorine, and nitrogen in the industrial wastes was studied in order to explore the potential value of waste. The results show that the alumina and sodium components in the industrial wastes are efficiently extracted, and the reaction process is promoted by iron and carbonaceous substances. The hazardous solid waste aluminum dross and the spent cathode carbon block are detoxified during the reaction process. The optimal reaction temperature is 1150 °C, and the residence time is 45–75 min. The extraction rate of Al2O3 is 92.4–93.3%, and the extraction rate of Na2O is 93.5–94.4%. The extracted alumina and sodium components can be used to prepare a series of high quality alumina.