Electrodeposition Of Manganese Metal And Simultaneous Production Of EMD By Ion-Exchange Membrane Electrolysis

The electrodeposition of manganese metal and simultaneous production of EMD by ion-exchange membrane electrolysis was carried out by the ion exchange membrane in place of the diaphragm used in the manganese electrolydeposition to solve the problems of low current efficiency, high energy consumption, high pollution and low utilization rate of equipment that exit in the manganese electrodeposition and manganese dioxide production,The current efficiency was found higher in the cathodic manganese electrodeposition of ionic membrane electrolysis than that in ordinary industrial diaphragm electrolysis by single factor experiments, meanwhile energy consumption values decreased. The voltage could be reduced by reducing the current density and pH and raising the temperature. The energy consumption could be reduced by reducing the current density, raising the temperature and keeping pH aroumd 7.5. The additives as Se and Na2SO3 added in the electrolyte could minish the manganese crystal, make the electrolytic manganese bright and keep the electrolyte clean. The pH maintained the same in 2h in the electrolysis. By orthogonal experiments, it was found that the significance of factors affecting the cell voltage was current density, temperature, concentration of manganese ion, concentration of ammonium sulfate, pH respectively. The significance of factors affecting the energy consumption was concentration of ammonium sulfate, concentration of manganese ion, current density, temperature, pH respectively. Optimized process was as follows: manganese ion concentration of 35g·L^-1, ammonium sulfate concentration of 130g·L^-1, current density of 400A·m^-2, pH of 7.5, temperature of 40℃.It was found that manganese dioxide could be produced on the anode at low temperature and the electrolyte's pH 3⁴ by tests. The results of single factor experiments show as follows: The cell voltage could be reduced by reducing current density and increasing the concentration of hydrogen ions. Higher current efficiency and lower energy consumption could be attained in the conditions of current density of 50A·m^-2, pH above 3 and low concentration of ammonium sulfate. By orthogonal experiments, it was found that the significance of factors affecting the cell voltage was current density, concentration of manganese ion, pH and concentration of ammonium sulfate respectively. The significance of factors affecting the energy consumption was pH, concentration of ammonium sulfate, current density and concentration of manganese ion recpectively. Optimized process was as follows: current density of 50A·m^-2, pH above 3, manganese ion concentration of 45⁵5g·L^-1.In the electrodeposition of manganese metal and simultaneous production of EMD by ion-exchange membrane electrolysis, the results showed that the anodic current efficiency and energy consumption were affected a little by the cathode factors, but the cathodic current efficiency and energy consumption were affected more by the anode factors. Optimized process was as follows: anodic manganese ion concentration of 50g·L^-1, anodic pH of 4, anodic current density of 40A·m^-2, cathodic manganese ion concentration of 40g·L^-1, cathodic ammonium sulfate concentration of 100g·L^-1, cathodic pH of 7.5, cathodic current density of 400A·m^-2.XRD patterns showed that the purity of electrolytic manganese with cubic crystal was high without miscellaneous peaks, and the crystal of electrolytic manganese dioxide is incomplete. The manganese dioxide in the anode products is greater than 82mass%. It indicated that pH of 7.5 and the addition of additives could make the cathodic polarization increase and the hydrogen reduction inhibited from the linear potential sweep.Compared with the industry product, manganese products can be produced on both anode and cathode by the method of electrodeposition of manganese metal and simultaneous production of EMD by ion-exchange membrane electrolysis in the advantage of higher utilization rate of equipment and lower evolution of hydrogen and oxygen. The cathodic and anodic current efficiencies are 97.53% and 98.62% respectively. The energy consumption of manganese and manganese dioxide are 3591kWh·t^-1 and 2245kWh·t^-1.