Microwave Efficient Extraction of Manganese from Low-Grade Pyrolusite by Pyrite Reduction Acid Leaching Process

Abstract

Manganese ore resources are the most important strategic resources of the country. With the continuous development of society, the demand for manganese mineral resources is increasing. However, little is known about the importance of resource strategies for this low-grade manganese ore. Herein, we used the microwave leaching (ML) method to recover and extract manganese (Mn) from low-grade pyrolusite and explore the Mn leaching behavior. Moreover, the effects of different factors (e.g., temperature, acid concentration, stirring rate, liquid-solid ratio, two ores ratio) on Mn leaching efficiency were investigated. At optimum conditions, Mn leaching efficiency of 96.2 % can be achieved at 150 min. Previous studies reported that using conventional leaching methods takes at least 240 minutes to reach 90 % leaching efficiency. Thus, the microwave leaching method has great potential in utilizing low-grade pyrolusite resources compared with the conventional leaching method. Furthermore, the kinetic analysis showed that the chemical reaction control step (1-(1-X)1/3=kt) could be used to explain the mechanism of the microwave leaching process, and the activation energy (Ea) of leaching process was 44.8 kJ/mol. The results imply that low-grade pyrolusite could be effectively utilized and developed by microwave heating in the future. This work provides a preliminary theoretical and technical basis for the recovery of manganese from low-grade pyrolusite.

Keywords: Low-grade pyrolusite, pyrite, microwave leaching, Mn extraction, kinetics