High-purity Manganese Sulfate Solution Preparation From Low-grade Pyrolusite And Applied To EMM And Electrocatalysis

Efficient use of low-grade pyrolusite was a technical problem.Manganese sulfate solution prepared by wet chemical method is a viable approach.Manganese sulfate solution was obtained by leaching Mn content of 18.9%of a low-grade pyrolusite from Hunan province with pyrites and concentrated sulfuric acid,or,in the two-ore-acid-leaching method.The optimum process conditions are determined:pyrolusite:pyrite:sulfuric acid(98%)=1:0.6:0.55(mass ratio),the temperature of leaching is 95?,the time of leaching is 2 h.Under these conditions,the leaching rate of manganese is up to 94%.The process is a suitable method for the development and utilization of low-grade manganese ore with low energy consumption,low cost and high leaching rate of manganese.A comparative study of four iron-removing methods found ammonium jarosite-goethite union method is most suitable for removal of iron from the solution.The optimum process conditions are determined:the temperature of leaching is 90?,the time of leaching is 1 h,the pH of the solution was adjusted to 4.0 with ammonia in twice,hot filtration.Under these conditions,the iron removal rate is up to 99.96%.Take ferrosilicon coprecipitation method to remove the silicon.Based on the forgoing,the pH of the solution was adjusted to 5.0?5.2 with ammonia,and insulation aging 4 h,the silicon removal rate is up to 99.9%.The remaining silicon content was only 11.00 ppm,iron content was only 8.66 ppm,and the manganese loss rate was lower.Heavy metal ions are removed by joining ammonium sulfide in the solution at room temperature and pressure.The optimum process conditions are determined:ammonium sulfide:reaction solution=0.023:1,the time of leaching is 50 min,the pH of the solution was adjusted to 5.0,all kinds of heavy metal impurities were removed deeply,and the manganese loss rate was lower.After a series of impurity purification process,the pure manganese sulfate solution was obtained,and used in the electrolysis reaction.The paper proposed a process of producing electrolytic metallic manganese with the pure manganese sulfate solution.The optimum process conditions are determined:constant current method,stainless steel as the cathode plate,stereotype as the anode plate,diaphragm electrolyzer,plate spacing is 50 mm,electrolysis cycle is 6 h,and citric acid compound or complex additives is added in the cathode solution.Under these conditions,the purity of electrolytic metallic manganese is up to 99.95%?99.99%.A process of preparing a novel manganese oxide electrode materials electrocatalyst for cyclohexanol oxidation in alkaline solution:firstly,manganese metal was deposited on the surface of the stainless steel plate;then,manganese surface load a layer of manganese oxide by the processing.Cyclohexanol conversion rate reached 92.83%,yield of adipic acid is about 81.6%.