Valorisation of sulphide tailings: A novel dilute reagents-based Mn extraction process

Abstract

The surging demand for manganese (Mn) and the concomitant scarcity of its primary resources have ignited interest in the extraction of this pivotal metal from unconventional sources, notably mining tailings. This study delves into the efficacy of dilute reagents as a judicious and discerning method for extracting Mn from sulphide tailings, concurrently offering environmental amelioration and substantial economic advantages. Specifically, the investigation concentrates on the adept and selective leaching of Mn from rhodochrosite (MnCO3) mineral under optimized conditions. Under the optimized conditions of 5 % HCl, a liquid-to-solid ratio of 5, a 90-minute leaching period, and a temperature at 50 °C, an exemplary 95 % leaching of MnCO3 was achieved while incurring a modest 12 % leaching of Fe, the principal impurity in the sample. Subsequent to the leaching process, MnO was efficiently extracted from the solution, exhibiting a purity surpassing 96 %, facilitated by the introduction of a diluted ammonium hydroxide solution (0.1 M NH4OH) at a solution pH of 9.8 and a temperature of 48 °C. The proposed methodology for reprocessing sulphide tailings offers numerous benefits, including cost-effective recovery and extraction, resulting from dilute reagents used and promoting a circular economy in mining. This research substantiates a significant stride towards the sustainable utilization of mining by-products, concurrently addressing both economic and environmental imperatives.