Study On Extracting Manganese Of Manganous-rich Slags By Hydrometallurgical Routes

The rich-manganese slag is a kind of green lumps with low water content and highhardness. It is mainly composed of Mn, Si, Al and a small amount of Ca、Fe、Mg、Baetc., and the percentage of them is as follows: manganese （30.26%）, silicon （17.07%）,aluminum （8.08%）.The methods and conditions of leaching manganese from the process ofpretreatment of rich-manganese slag were discussed. It was proved that alkalinepretreatment-acid leaching was a good technology in this work. The technologicalcondition and index to reach a better effect is also discussed. Making sure featpretreatment condition is that: The concentration of alkali9mol/L, the mass ratio of thealkali and rich-manganese slag is3:1, react at77℃for3h, at this condition, it produceless hydrogen sulphide in the acid-leaching process; Leacing rate of manganese attained98.88%at the concentration of sulfuric acid is1mol/L, the mass ratio of the alkali andalkaline residue is9:1, react temperature at90℃for2h.In the leaching process, Fe2+, Al³⁺and some other heavy metals impurities enterinto leaching solution. The impurity removal in lixivium was discussed in this study.Hydrolyzation-precipiation method was chosen to remove Fe³⁺and Al³⁺.The pH valuewas adjusted to5⁶, and Fe³⁺and Al³⁺were converted to Fe（OH）3and Al（OH）3whichcould be removed as precipitant. Results show that the concentration of Fe³⁺was cutfrom2.18g/L to less than0.5mg/L. the removal rate of it was99.97%. SDD waschosen as precipitant to remove heavy metal impurity to purify MnSO4leaching liquid.Recovery of manganese by electrolytical method from the lixivium was proposed:determined the ammonium concentration and added ammonium sulfate made theconcentration reaching120g/L, adjust the pH value at6.5-7, constant temperatureelectrolysis at37to40℃. The purity of manganese achieves99.8%; and it is mainlycomposed of α-Mn from analysis of X-ray diffraction patterns.