The Process and Mechanism of Electrolytic Manganese Anode Slime Lead Removal

Abstract

Production of electrolytic manganese metal inevitably produces a certain amount of solid wasteelectrolytic manganese anode slime, with a high manganese content, but its difficult to recycle due to the presence of other impurities. Firstly, the washing method was used to remove the anode slime soluble salts, then its chemical composition and phase were analyzed. The flame atomic absorption spectrometer and X-ray fluorescence (XRF) analysis showed the anode slime mainly contained Mn, Pb, Ca, Fe, Cr, K, Se and other metal elements, with the average manganese content 45% and the lead 3.5%;X-ray diffraction (XRD) preliminary analysis showed that the anode slime was a colloidal system mainly containing the spinel structure of MnO2 and complex salts PbMn8O16xH2O phase, by high temperature roasting, the anode slime transformed from hexagonal system to cubic system , and the basic structure unit from edges connection to surfaces connection,the change of length,angle and fracture of manganese-oxygen bond provided the channel for the lead leaching;TG-DTA analysis showed that anode slime was dominated by water loss below 400°C,and started to lose oxygen beyond 425°C, and clear endothermic peak was observed at 500°C and 700°C, which showed the anode slime crystal structure changed at 500°C, anode slime weight loss tending to be gentle with some Mn2O3 generation at 700°C, and roasted crystal stabilizing to Mn2O3. Preliminary roasting and leaching purification technology route was proposed according to the above analysis results, and analysis of the purification process related factors was made. Under the condition of natural ventilation, anode slime was roasted at 700°C, and fully leached in 2mol/L HAc , with liquid-solid ratio 10:1, then leached anode slime was characterized by XRD and flame atomic absorption test, the results showed that anode slime manganese content increased from 45% to 67.5%, the lead content decreased from 3.5% to 0.1%, XRD indicated that the anode slime existing phase was Mn2O3. Anode slime after purification treatment can be further used for battery manganese source material, which provides an effective approach for the recovery of manganese anode slime utilization.