Research On Distribution And Behavior Of Mg²⁺ In Manganese Electrolysis System

Basing on the industry common problem that the concentration of impurity ions was higher than that of main metal ions in electrolytic manganese system,the equilibrium distribution of Mg in the process of manganese electrolysis,the effect of Mg²⁺on the process of manganese electrolysis and the physicochemical properties of manganese sulfate solution were studied.In this paper,the Rhodochrosite in Zunyi of Guizhou Province was taken as an research object.Under the guidance of the current production process conditions of electrolytic manganese,the manganese leaching,purification and electrolysis system were deeply studied,and the equilibrium distribution rule of Mg in the whole system was obtained.By controlling the difference of Mg²⁺concentration and temperature,the influence of it on the physicochemical properties?viscosity,density,electrical conductivity and surface tension?of the manganese sulfate solution was revealed.Finally,the effects of Mg²⁺concentration,ammonium sulfate concentration and current density on current efficiency,macroscopic and microscopic morphology of the cathode plates were studied,and the reasonable technological conditions of the electrolysis process were mastered.As a result,the harm of magnesium to electrolytic manganese system was quantified,which would provide theoretical support for the subsequent removal of Mg²⁺and electrolytic manganese production.?1?Study on the effect of Mg²⁺on the leaching process.Under the current industrial leaching conditions of rhodochrosite,increasing the concentration of Mg²⁺in the reaction solution,the leaching rate of manganese in rhodochrosite would decrease.When the concentration of Mg²⁺was increased from 0g/L to 50g/L,the leaching rate of manganese would decrease.from 84.19%to 76.39%,which was significantly lower than the leaching rate of manganese in current industrial production.At the same time,the concentration of Mg²⁺in the leaching solution would be enriched by 2-3 g/L every leaching cycle.?2?Study on equilibrium distribution of Mg in electrolytic manganese system.Calculations was based on that magnesium in ores was100g.During the leaching process,38.19%of magnesium entered the solution and 61.8%entered the leaching residueA small amount of Mg could be took away by the slags during the process of removing iron of neutralizing method and removing heavy metals of SDD method.The Mg could be took away at 22.45%and 0.4%by the removing iron slag and heavy metal slag,respectively.In the process of electrolysis,the content of Mg was about87.76%in the anode solution,that in the cathode solution was 11.87%,that in the electrolytic metal was about 0.08%,and that in the anode slag was about 0.34%.?3?The effect of Mg²⁺on the physicochemical properties of manganese electrolyte was studied.When the temperature was constant,with the increasing of Mg²⁺concentration in electrolyte,the density,conductivity and viscosity of manganese sulfate electrolyte increased gradually at different temperature gradients,while the surface tension decreased gradually.When Mg²⁺in manganese electrolyte increased from 10g/L to 30g/L,the density of manganese sulfate electrolyte increased from1.17g/ml to 1.26g/ml,the viscosity increased from 2.63mm²/s to 2.12mm²/s,the conductivity increased from 294ms/cm to 382ms/cm,and the surface tension decreased from 87.94N/cm to 86.71N/cm.?4?The interactive effect of Mg²⁺,ammonium sulfate concentration and current density on the electrolysis process was studied.?1?Within the scope of the study,with the increasing of Mg²⁺concentration in electrolyte,the current efficiency decreases gradually.When the concentration of?NH₄?₂SO₄ and Mg²⁺in electrolyte was constant,the current efficiency increased first and then decreased with the increasing of current density.With the increasing of?NH₄?₂SO₄ concentration in electrolyte,the current efficiency increased gradually.?2?When the concentration of Mg²⁺in electrolyte increased from 15g/L to 35g/L,the current efficiency decreased from 68.73%to 62.54%.When the current density increased from 300A·m^-2 to 400A·m^-2,the current efficiency of manganese increased from 65.32%to 66.23%.When the current density increased from 400A·m^-22 to500A·m^-2,the current efficiency of manganese decreased from 66.23%to 64.92%.Therefore,in the electrolysis process,the reasonable electrolytic conditions were as follows:lower Mg²⁺concentration,current density of 400A·m^-2,?NH₄?₂SO₄concentration of 100 g/L.The micro-structure of electrolytic manganese indicated that the metal manganese sheet grew layers by layer,with the different conditions of electrolysis,the growth angles were also different..The larger the angle was,the greater the current efficiency would be.