Al and other critical metals co-extraction from coal gangue through delamination pretreatment and recycling strategies

Abstract

Coal gangue is an underused resource and there is a lack of its utilization in the green economy. This work aims at the clean recovery of critical metals in coal gangue, with the development of a recycling extraction process through repeated utilization of ammonia and ammonium salts, and development of delamination pretreatment methods to improve the extraction efficiency in relation to structural characteristics of aluminosilicate minerals in coal measures. The results showed that the pretreatment could replace the powder process, significantly improve the extraction efficiency and, simultaneously, inhibit the leaching of harmful elements. The leaching rates of Al, Li and Ga can be increased to 62.74%, 86.56%, and 46.18%, respectively, while the leaching of Pb was inhibited. Polymetallic products are potential raw materials for low-cost composite materials. The study developed and optimized a set of new ideas to promote the green extraction and utilization of critical metals in coal gangue.