Beneficiation of diamond mine residues for the synthesis of Mg containing compounds

Abstract

The aim of this study is to develop a process for the valorisation of diamond mine residues. This entailed a combination of thermochemical solid-solid reactions between the mine residues and ammonium sulphate, followed by aqueous dissolution, to maximise the extraction of strategic metals from various mineral-bearing materials. The thermochemical treatment of the mine residues with ammonium sulphate was found to be non-selective. Subsequently, thermogravimetric analysis data of the obtained products was used to develop a roasting programme allowing Fe to be separated from Mg before leaching. Brucite and Mg/Al layered double hydroxides were successfully synthesised from the leachates after elemental extraction and separation. The talc content of the leach residue could be increased substantially, accompanied by an improvement in colour clarity. This study successfully proved the formation of Mg containing products during the beneficiation of diamond mine residues.