Electrolytic manganese residue pretreated by filter press-water washing and carbide slag: Manganese recycling, depth harmless and dispersion

Abstract

Filter press-water washing and carbide slag (CS) were utilized for recycling manganese, ensuring depth harmless and dispersion of electrolytic manganese residue (EMR). Mn2+ recover profit, pH value, leaching concentration and particle sizes of treated water-washed EMR (TWEMR), as well as the microstructure and composition changes during disposal process was explored. Mn2+ recovery efficiency was 94.11% with a profit of 10.56 $/(1 t EMR). CS primarily served as a dispersant and disposal agent, with a stepwise addition of CS (40% + 60%) and a change in stirring process (slow speed for 5min and fast speed for 10min) further enhancing the reaction process. Mn2+ and NH4+ leaching concentrations can be reduced to below the detection limits, while Mg2+ concentration reduced to 1.26mg/L. Moreover, the dispersion of water-washed EMR (WEMR) was realized. Mn2+ and Mg2+ were solidified/stabilized in forms such as MnOOH, Mn3O4, Mn2O3, MnCO3, Mg(OH)2 and MgCO3. Furthermore, these ions could also be solidified/stabilized through the formation of ettringite, thaumasite, butlerite and calcium (aluminate) silicate hydrate (C-(A)-S-H) during the reaction process. This study provides a method for manganese recycling from EMR, ensuring depth harmless and dispersion of WEMR filter cake.