Study on the high-efficiency separation of Fe and Mn from low-grade pyrolusite and the preparation of LiMn2O4 materials for lithium-ion batteries

Abstract

• No any reducing agent is used in whole recovery process. • The separation effect of pyrolusite by sulfidation roasting is satisfactory. • The conversion process of manganese oxide is studied in detail. There is a serious shortage of high-grade manganese ore resources, so the development and utilization of low-grade manganese ore are of great significance. In this paper, the mixed roasting/water leaching method of sulfuric acid and pyrolusite is used to efficiently recover Mn and Fe elements. Under the optimal process conditions, acid/ore ratio of 2:1, water/acid ratio of 1:5, the roasting temperature of 650 °C, and holding time of 4 h, the leaching rates of Mn and Fe are 99.10% and 0.67%, respectively. Additionally, the conversion process between manganese-containing precipitate and manganese oxide is studied, and high-purity Mn 3 O 4 is obtained. LiMn 2 O 4 , an electrode material for lithium-ion batteries, is successfully prepared by solid-phase synthesis with Mn 3 O 4 as a manganese source. The initial charge specific capacity of the LiMn 2 O 4 is 115.7 mAh·g −1 at 0.1C. Additionally, the charge specific capacity of the LiMn 2 O 4 is still 78.64 mAh·g −1 after 100 cycles at 1C. The process does not use any reducing agents, surfactants, etc., and has the characteristics of short, simple, easy-to-operate, economical, and reasonable process, which is helpful to realize the efficient recovery and reuse of manganese and iron resources in the pyrolusite.