Extraction of Aluminum and Preparation of Polymerized Aluminum Ferric Sulfate from Red Mud

Abstract

By employing an “alkali calcination‐water leaching” integrated extraction technique, the separation of aluminum and iron components in red mud is achieved through the extraction of aluminum oxide and the preparation of polymeric aluminum iron sulfate (PAFS) water treatment agent. Basic characteristics of raw material red mud were characterized. The process parameters of activation calcination, leaching, and preparation of water treatment agent were determined. The prepared PAFS was characterized in terms of its fundamental properties and waste water treatment capacity. Results showed that the content of Al2O3 and Fe2O3 in red mud was 12.98 % and 6.09 %, respectively, distributed in the amorphous phase, while SiO2 and CaO existed in form of feldspar, calcite, and calcium silicate. During calcination stage, use NaOH as the activation medium, over 43 % Al2O3 could be extracted under the optimal activation and leaching process parameters. After acid leaching of the water‐leached residue, PAFS water treatment agent was prepared by utilizing the resultant acid leaching solution with NaOH as PH regulator. By optimizing the process parameters for preparation, an impressive turbidity removal rate of 97.52 % was achieved for the resulting PAFS. This study presents a viable approach for achieving significant reduction and maximizing the value‐added utilization of red mud.

Preparation and Application of Polyaluminum Ferric Sulfate from Red Mud: Behaviors of Leaching, Polymerizing, and Coagulation

“…Red mud is the residue of aluminum smelting from bauxite, which has a strong alkalinity. 1 The weathering of red mud particles in the exposed environment easily causes air pollution. Furthermore, the strong alkalinity of red mud will erode the building surface, alkalize the soil, and affect the planting.…”