Comprehensive Utilization of Red Mud Through the Recovery of Valuable Metals and Reuse of the Residue

Abstract

An integrated technological route for comprehensive utilization of red mud through the extraction of valuable components and reuse of the magnetic residue is proposed. In this study, inductively coupled plasma atomic emission spectroscopy, X-ray fluorescence, X-ray powder diffraction, and vibrating sample magnetometer were used to characterize the process. The process includes sintering, alkaline leaching to recover Na and Al, and removal of lead ions from wastewater by magnetic residue containing magnesium ferrite. The effects of various parameters were systematically investigated, and the optimal conditions were determined as: sintering temperature of 1150 °C and duration of 60 min, the mole ratio of CaO/SiO2 of 3, Na2O/Al2O3 of 1.2, and MgO/Fe2O3 of 1 in the raw material. Under the conditions, the results showed that approximately 74% Al and 95% Na were recovered from red mud by this route. The leach residue exhibits magnetic and adsorption properties, its adsorption capacity reaching about 70 mg/g at the initial Pb2+ concentration of 80 mg/L. Therefore, it may be a promising candidate in wastewater treatment and other fields.