Manganese Electric Enhanced Leaching From Electrolytic Manganese Residues

China is a big country in the production of electrolytic manganese,and the output accounts for 96%of the world output.The electrolytic manganese slag will be produced in the process of electrolytic manganese production.With the rapid increase of demand for manganese,the electrolytic manganese slag will also increase rapidly.The storage of EMM slag in China exceeds 160 million tons,and the annual growth rate is more than 10 million tons.The electrolytic manganese slag contains a large amount of soluble manganese sulfate,and it also contains a small part of the refractory manganese.In addition,manganese sulfate can also convert high-priced refractory manganese due to the combination of oxygen and microorganism in the air during the process of storage.How to recover manganese from electrolytic manganese slag efficiently and reduce its environmental impact while reducing the loss of manganese resources has become a hot issue in the pollution control and recycling of electrolytic manganese slag.Therefore,the paper takes the manganese slag stored in an electrolytic manganese company in Guangxi Province as the research object,analyzes its physical and chemical characteristics,and uses two processes,sodium sulfite and electric field in coordination with sodium sulfite to strengthen the leaching of manganese from the electrolytic manganese slag.The influence of environmental factors on the leaching rate of manganese is discussed in detail.The main conclusions are as follows:1.Electrolytic manganese slag mainly contains CaSO₄·2H₂O and SiO₂,but also contains a small amount of（NH₄）₂Mn₂（SO₄）₃,Mn（NH₄）₂SO₄·6H₂O and other soluble double salts and calcium silicate(Ca₈Si₅O₁₈,Ca₂SiO₄).Some manganese exists in the form of insoluble MnO₂.2.The results show that the leaching rate of residual manganese in electrolytic manganese slag is 93.55%under the optimum leaching conditions（reaction temperature is333 K,sulfuric acid dosage is 10wt%,sodium sulfite dosage is 0.21 mol/L,solid-liquid ratio is 1:10）.The leaching process is controlled by diffusion interfacial chemical mixing,and the apparent activation energy is 18.24 k J/mol.3.The results show that under the conditions of reaction temperature 333 K,60 mA/cm²,8wt%H₂SO₄and 0.16 mol/L sodium sulfite,the leaching efficiency of manganese is 96.63%.The Arrhenius expression of leaching process is:1-2/3X-（1-X）^2/3=4.069exp（19680/RT）t.Generally speaking,compared with sodium sulfite enhanced leaching process,the amount of H₂SO₄and sodium sulfite decreased by 20%and 24.53%,which significantly reduced the cost.At the same time,on this basis,we carried out a scale-up experiment,under the effect of electric field,the leaching rate of manganese is 87.25%.