| The paper proposed a high efficiency and low cost process of producing electrolytic metallic manganese from low grade manganese oxide ore according to the low grade, many impurities and long process line of manganese ore in China. In this paper, we take Na2SO3as potential mediating agent in the reductive leaching process, remove iron using jarosite process, prepare manganese sulfate using one pot method through sodium sulfide purification process, electrolytic metal manganese using double membrane tri-chambers technique in the MnSO4-(NH4)2SO4-NH3-H2O system. The process is observed and optimized.The E-pH diagrams of Mn-H2O, Fe-H2O and H2O2-H2O was drawn through the calculation of leaching basic thermodynamics data. When pH<1.61,0.77<E<(1.228-0.1182pH), Mn2+and Fe3+can coexisted and it showed that there were two kinds of solution potential regulator committed to leaching and deironing on the conditions that temperature was25℃, pressure was101.325KPa,[Mn]=lmol/L,[Fe]=lmol/L Hydrogen peroxide and sodium sulfite were selected as representative to carried on the experience of leaching and deironing respectively, the processing conditions that hydrogen peroxide was used as electric potential regulator were optimized as follows:temperature was90℃, amount of sulphuric acid was100g/L, amount of hydrogen peroxide was0.5mol/L, leaching reaction time was1.75h. When the final PH value was2.5that ammonia water was used to mix slurry, the precipitation reaction time was1.25h, the leaching rate of manganese, iron and silicon was97.8%,0.02%and1.2%. The basic thermodynamics data was revised on the base of experiment, the coexistence area of Mn2+and Fe3+have changed as follows:temperature was90℃, pressure was101.325KPa,[Mn]=0.4mol/L,[Fe]=0.6mol/L on the conditions that pH<1.78,0.858<E<(1.361-0.1477pH). The processing conditions that sodium sulfite was used as electric potential regulator were optimized according to the revised thermodynamics data as follows:temperature was90℃amount of sulphuric acid was110g/L, amount of sodium sulfite was 0.43mol/L, leaching reaction time was100minutes. When the final PH value was2.5that ammonia water was used to mix slurry, the precipitation reaction time was1.25h, the leaching rate of manganese, iron and silicon was98%,0.03%and1.1%. The sodium sulfite was chose as reducing agent finally after compared both their amount and reaction capacity. The research to the purification process of leaching solution indicated that the effect of purification to be best when the final response pH value was4.5. The process of leaching, iron purification and eliminates other contaminating metal ion were integrated, the waste electrolyte was used as leaching agent of multistage leaching and multistage backflush to ensure the manganese ion concentration in the purification solution. One-pot reaction was studied to reduce the flow and solve the problem that follow-up impurity difficult to filter and other questions.The optimum process conditions are determined by:the concentra-tion of (NH4)2SO4is120-130g/L, the temperature of electrolysis is35℃and the density electric current is350A/m2according to the E-pH of the MnSO4-(NH4)2SO4-H2O system and the (NH4)2SO4-NH3-H2O system. And the cathodic current efficiency of the electrolytic metal manganese is up to77%. The appearance of electrolytic manganese piece was observed by metallographic microscope. To improve electrolysis process, The equipment with double membrane and three rooms that masculine and feminine elements ion exchange membrane were used as electrolytic films was researched to prepare electrolysis manganese, the average cathode efficiency may reached80%. |
PDF Full Text Request