Mechanism of enhanced enrichment manganese from manganese ore-pyrite under microwave heating: Process optimization and kinetic studies

Realizing efficient leaching of manganese elements from low-grade manganese ore is crucial from a strategic perspective to address the insufficient supply of high-grade manganese ore resources. Meanwhile, energy and environmental issues are becoming increasingly crucial under carbon neutrality. This work introduced micro-wave technology into the low-grade manganese ore leaching process, and the pyrite was used as a reducing agent. The leaching behavior of manganese by microwave leaching was investigated. The results showed that 98.6% Mn were leached using the microwave leaching method under optimal conditions: 400 rpm stirring rate, 1.5 M sulfuric acid concentration, a liquid-solid ratio of 10 mL/g, low-grade manganese ore-pyrite ratio of 10/2 and leaching time of 150 min. In contrast, about 92.0% Mn was achieved using conventional leaching methods. Moreover, the kinetic behavior of manganese leaching was studied using four unreacted shrinkage core models. The kinetics result indicated that the chemical reaction control model (1-(1-X)1/3 = k1t) could be used to describe the microwave leaching process. These results have preliminary guidance for the production practice of microwave-assisted leaching of low-grade manganese ore.