Detoxification and Extraction of Solid and Hazardous Wastes for the Preparation of Molecular Sieves

The discharge of industrial solid/hazardous wastes (such as aluminum dross, spent cathode carbon blocks, coal gangue, and carbide slag) causes potential environmental problems and wastes resources. An innovative method for preparing molecular sieves using varied solid/hazardous wastes is proposed. Aluminum dross is deeply denitrified to extract alumina source under a high concentration of sodium hydroxide. Denitrified aluminum dross, desilicated coal gangue, spent cathode carbon blocks, and carbide slag are synergistically reacted at high temperature to further extract alumina source. Alumina and silica sources are obtained via desilication of coal gangue which is used as raw materials to synthesize molecular sieve materials. The results show that the reaction rate of aluminum nitride in aluminum dross after leaching with high-concentration alkali solution reaches more than 99%, while the extraction rate of alumina reaches 40% (the extraction rate of alkali-soluble alumina is almost 100%). The highest sodium oxide recovery rate for various solid/hazardous wastes is 96.23%, and the alumina extraction rate is 95.2%. The molecular sieve prepared from silica and alumina sources has good crystallinity with an average particle size of 4.46 μm, a whiteness of 94.9, and a calcium exchange capacity of 310 mg/g.