A cleaner and efficient extraction of Mn from low-grade Mn carbonate ores by ball milling-enhanced Fe2(SO4)3 leaching: Acid consumption reduction

Abstract

High acid consumption is a common problem in the treatment of low-grade Mn carbonate ores by H 2 SO 4 leaching process. In this study, Fe 2 (SO 4 ) 3 solution was used to replace the commonly used H 2 SO 4 solution as a leaching agent to leach Mn from low-grade Mn carbonate ores, and therefore the acid consumption was reduced. Simultaneously, mechanical activation by ball milling was used to activate the Mn-bearing minerals in the ores and promote their dissolution in the Fe 2 (SO 4 ) 3 solution. Results show that the leaching efficiency of Mn reached ~100% and the percentage of Fe remaining in the leachate could be controlled to < 3% at optimized conditions, which was a very low level beneficial to the subsequent separation of Fe and Mn. Compared with mechanical activation by wet ball milling, mechanical activation by dry ball milling was more capable of destroying the crystal structure of Mn-bearing minerals and improving their chemical reactivity with Fe 2 (SO 4 ) 3 in the leaching agent to enhance their dissolution. This study provides a cleaner and efficient hydrometallurgical process for the extraction of Mn from low-grade Mn carbonate ores as well as a novel approach for the treatment of Fe 2 (SO 4 ) 3 -containing waste solutions, clearly exhibiting an environment-friendly feature over the traditional acidic process. • Fe 2 (SO 4 ) 3 solution was used as a leaching agent to offer a green process. • Mechanical activation proved to be necessary for the Fe 2 (SO 4 ) 3 leaching of Mn carbonate ores. • The percentage of Fe remaining in the leachate could be controlled to < 3%.