The pre-oxidation acid mine drainage(AMD)generated during mining process exhibits a certain degree of acidity and contains a large amount of metal ions and sulfates.Traditional lime neutralization methods not only con-tribute to environmental pollution,but also cause resource wastage.This study employed a process involving nanofil-tration,reduction,vacuum concentration,and crystallization to treat pre-oxidation AMD and produced magnesium ferrous sulfate crystals.The retention rate of different metal ions during nanofiltration was investigated,and the influ-ence of Fe3+reduction during the preparation process of magnesium ferrous sulfate were explored,along with the im-pact of crystallization conditions on crystal purity and yield.The results showed that the retention rate of nanofiltra-tion for all metal ions reached over 93%,and the retention rate for iron and magnesium reached 98%.The optimal Fe3+reduction effect occurred at pH of 1.0,temperature of 35℃,and reaction time of 40 minutes.When the concen-tration ratio of the mother liquor was 1∶2,the crystallization temperature was 35℃,and the stirring rate was 240 r/min,the recovery rates of iron and magnesium in mother liquor were 31.31%and 13.48%,respectively,and the pu-rity of the product could reach more than 98%.Structural analysis of the crystals confirmed that the product was magnesium ferrous sulfate.Compared with the traditional lime neutralization method,this combination process could not only achieve pre-oxidation AMD treatment,but also realize resource recovery of ferrous magnesium sulfate.
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