The Technology Study Of Recovering Soluble Manganese From The Electrolytic Manganese Residue By CO₂

As a kind of necessary metallurgical and chemical material, manganese metalplays an important role in China’s national economy, which mainly obtained byelectrolysis method at present. Electrolytic manganese residue is the main solidwastes in the electrolytic manganese industry, which contains higher concentration ofsoluble manganese, and will pollute the environment seriously and result in resourcewaste by improperly handled. In the meanwhile, large amounts of carbon dioxide areproduced in the electrolyzing manganese production process, so how to reduce carbondioxide emissions is also an important issue.Taking the electrolytic manganese residue from one electrolytic manganesecompany in guangxi as the study subject, we researched the fundamental propertiesand washing conditions of the residue in this study. Aiming at recycling the solublemanganese in the electrolytic manganese residue, the recycling technologic flow ofsoluble manganese by using low concentration of industrial carbon dioxide(thevolume ratio is about12%) was simulated, and the treatment design was set, whichprovided the basis for the possible industrial application.The chemical composition, surface morphology of electrolytic manganese residuewere analyzed by XRF and SEM-EDX in this thesis, the results show that thecomposition of residue is very complex, the particle sizes span a wide range and itsstructure is relatively unconsolidated, the major ingredient is SiO2and metal oxidesuch as CaO、Fe2O3etc., and it contains higher levels of manganese, the mass ratio ofMn2+is about4.88%, whlie other heavy metals such as Cu、Zn、Pb、Ni etc. have lowconcentrations.By simulating the precipitation reaction between low concentration of carbondioxide(the volume ratio is about12%) and manganese ion in the solution, this studyreflected the recovery efficiency of soluble manganese by using industrial carbondioxide. As the main controlling factor of recycling soluble manganese by CO2, theincreasing initial pH of the electrolytic manganese residue washing fluid leaded toenhance the recovery efficiency until9.5, then the recovery efficiency of solublemanganese remained stable which reaching98%. And in the scope of the test, thevolume rate、flow of CO2and the rotate speed did not much affect to recoveryefficiency.The kinetics of recycling soluble manganese by CO2was studied to analyse thecontrol step. The results show that the precipitation order of precipitation reaction is 2.44with the activation energy about109.84KJ/mol; crystallization kinetics studyshows that convert ratio improves with the increase of reacting temperature, whichmeans the increase of temperature promote the precipitation of manganese and thecrystal nucleus formation. The apparent reaction rate of nucleation stage and thecrystal growth period both improve with the increase of reacting temperature, but theformer is smaller, which means nucleation stage is much more difficult. So nucleationstage is the control step.For the standardized discharging of the washing fluid after recovery reaction,ferric chloride was used to treat the wastewater containing low concentration ofmanganese in this study. The results show that pH is the main control factor ofremoving manganese by using ferric chloride, and manganese is mainly in the form ofmanganese oxide in the precipitate.In the end, the industrial design solution of1000m3/d for Daxing manganese orewas presented on the basis of the above results.