Enhanced manganese leaching from electrolytic manganese residue by electrochemical process and Na2SO3

Abstract

Electrolytic manganese residue (EMR) is a general industrial solid waste containing manganese (Mn) and heavy metals that is produced in the process of electrolytic metal manganese. In this study, the leaching efficiency of Mn from EMR was improved by using Na2SO3 and electric field. The results showed that Mn leaching efficiency reached 96.63 % (333 K, 8 wt% H2SO4, 60 mA/cm2 current density and 0.16 mol/L Na2SO3), which was 30.56 % higher than leaching with H2SO4 and 12.76 % higher than leaching by using electric field. The kinetic results based on the unreacted contraction nucleus model showed that the process is controlled by a mixture of external diffusion interfaces and chemical reactions, with a calculated activation energy of 19.68 kJ/mol. Na2SO3 and electric field enhanced the leaching of Mn by removing the compound salts layer wrapped around the outside of Mn and reducing the release of high-valent Mn to divalent Mn. This study provide a novel approach for the utilisation of EMR.