Treatment and characterization analysis of electrolytic manganese anode slime

摘要

This research aims at providing the basic database for reasonable treatment of electrolytic manganese anode slime by comparing its composition, phase and crystal structure before and after the specific treatment. To describe original samples' surface physical and chemical characteristics, X-ray fluorescence (XRF), Flame Atomic Absorption Spectrometry (FAAS), X-ray diffraction (XRD), Scanning Electron Microscope and Energy Dispersive Spectrometer (SEM-EDS) and TG-DTA were used. Then, used XRD and SEM-EDS to describe the system features and characterization of the anode slime performed by Washing-Roasting. Through application of XRF and FAAS, element content in anode slime and the source of each element were analyzed. The results show that the original samples of anode slime mainly contains Mn, Pb, Ca, Se and Sr and averagely the contents of manganese and lead are 47% and 7.46%, respectively. XRD analysis shows that main phases of the anode slime are KxMn8O_(16),MnO2,PbMn8O_(16) and Pb2Mn8O_(16), and MnO2 in the slime has a mixed crystal structure of α-MnO2,β-MnO2,γ-MnO2,δ-MnO2. SEM-EDS analysis indicates that the anode slime has dense "mineral" phase. TG-DTA/DTG analysis shows that at the temperature of 0 ～ 573 °C, water in δ -MnO2 lattice is desorbed; 573 ～ 655 °C, MnO2 starts to lose oxygen and turn into Mn2O3; 900 ～ 1000 °C Mn2O3 loses oxygen and turn into Mn3O4. Anode slime under different roasting temperature were characterized by XRD and SEM-EDS. The result shows that when roasting temperature reaches higher than 700 °C, bond energy of Pb-O is broken; when higher than 800 °C, the crystallinity of anode slime further increases and the dense structure of anode slime is broken, which provides an effective way to remove lead from the slime; when higher than 900 °C, Mn2O3 turns into Mn3O4 and the channels in the anode slime become much looser and wider for better leaching of impurity ions.