Preparation and characterization of high specific surface area Mn3O4 from electrolytic manganese residue

Mn 3 O 4 powders have been produced from Electrolytic Manganese Residue (EMR). After leaching of EMR in sulfuric acid, MnSO 4 solution containing various ions was obtained. Purifying the solution obtained and then adding aqueous alkali to the purified MnSO 4 solution, Mn(OH) 2 was prepared. Two methods were employed to produce Mn 3 O 4 . One way was oxidation of Mn(OH) 2 in aqueous phase under atmosphere pressure to obtain Mn 3 O 4 . The other way was roasting Mn(OH) 2 precursors in the range of 500°C to 700°C. The prepared samples were investigated by using several techniques including X-ray powder diffraction (XRD), Fourier Transformation Infra-Red (FTIR) spectra, and Brunauer-Emmett-Teller (BET) specific surface area instrument. Particle distribution and magnetic measurements were carried out on laser particle size analyzer, vibrating sample magnetometer (VSM). Through XRD, FTIR and determination of total Mn content (TMC), the products prepared were confirmed to be a single phase Mn 3 O 4 . BET specific surface areas can reach to 32 m 2 g −1 . The results indicated that products synthesized by aqueous solution oxidation method had higher specific surface areas and smaller particle size than those prepared by means of roasting. However the products prepared using the above two methods showed no obvious differences in magnetic property.