Study On Step Extraction Of Manganese,Lead,Selenium And Tin From Electrolytic Manganese Anode Slime Based On Sulfur Conversion

With the shortage of manganese ore resources,the research on recovering manganese from secondary resources is imminent.The manganese content in electrolytic manganese anode slime is 40%-50%,which is close to the requirement of rich manganese ore with manganese content of 48%,which has important recovery value.However,due to the miscellaneous structure of electrolytic manganese anode slime,the imperfect crystal shape,and the difficulty of comprehensive utilization,most manufacturers currently sell them cheaply or store them in large quantities,resulting in serious waste of resources and environmental pollution.Electrolytic manganese anode slime contains a large amount of strategic metals such as Mn,Pb,Se,Sn,etc.The previous research mainly focused on the separation of manganese and lead in anode slime,ignoring the recovery of rare resources selenium and tin.This paper Taking the anode slime produced by an electrolytic manganese plant in Qinghai Province as the research object,in view of the shortcomings of the previous separation methods of valuable elements in electrolytic manganese anode slime,a technology for the distribution and extraction of manganese,lead,selenium and tin in electrolytic manganese anode slime based on sulfur conversion was proposed.The thermodynamics of the sulfide roasting and leaching process of manganese,lead,selenium and tin in anode slime were analyzed,and the phase transformation and morphological evolution of anode slime before and after roasting were revealed.Simulations were carried out to explore the effects of different roasting and leaching process parameters on the leaching rates of manganese,lead,selenium and tin,and the adaptability of the sulfur reduction roasting-sulfuric acid leaching method was studied.The phase transformation and morphological evolution of anode slime before and after high temperature roasting show that high temperature sulfidation roasting can destroy the stable structure of anode slime,and 300℃roasting condition is not enough to completely convert Mn O₂ in anode slime.High temperature is beneficial to the formation of Mn SO₄ and Pb S.At 400°C,the increase in the amount of sulfur is beneficial to complete the reaction and promote the formation of Mn S.The sulfidation kinetics of manganese dioxide in anode slime shows that the reduction process of manganese dioxide by sulfur is controlled by the interfacial chemical reaction,and its kinetic equation is:1-（1-x）^1/3=32.03exp[-35367/RT]t,the activation energy is 35.367k J/mol,the activation energy is small,which proves that manganese dioxide is easily reduced by sulfur.The thermodynamic analysis of the roasting and leaching process shows that after the anode slime is sulfidized and roasted,Mn⁴⁺in the anode slime is reduced to acid-soluble Mn²⁺,while lead is precipitated in the form of Pb S and Pb SO₄,Sn O₂ is reduced to Sn SO₄ and Sn S,and Se O₂ is released from the solid phase.Transfer to the gas phase,and the suitable environment for extraction of manganese,lead,selenium and tin is p H=2-5,and the potential is between 0.3 and 0.85 V.The process parameters for the separation of manganese,lead,selenium and tin in electrolytic manganese anode slime were studied,and it was concluded that the suitable technological conditions for the sulfidation conversion and leaching of Mn,Pb,Sn,and Se were as follows:the roasting temperature was 400°C,and the mass ratio of sulfur to anode slime was 1:1.The roasting time was 10 min,the sulfuric acid concentration was 8%,the liquid-solid ratio was 10:1,the leaching temperature was 25°C,the leaching time was 5 min,and the stirring rate was 100 r/min.The distributed extraction of manganese,lead,tin,selenium and harmful slag in electrolytic manganese anode slime is realized.After sulfuric acid leaching,98.1%Mn,80.5%Sn,30%Se can be recovered in the leaching solution,99%Pb can be enriched in the leaching residue,and70%Se can be recovered in the volatile dust.