铵盐体系电解锰渣中石膏的转变规律

Transformation law of gypsum from electrolytic manganese residue in ammonium salt system

电解锰渣已成为阻碍电解锰行业发展的瓶颈,其中锰渣含有的大量石膏是限制其资源化利用的关键。针对锰渣中石膏浸出问题,本文研究了NH_(4)HCO_(3)和NH_(4)Cl用量、浸出初始pH、浸出时间、浸出温度对锰渣中石膏转变规律的影响。研究结果表明,当锰渣与NH_(4)HCO_(3)和NH_(4)Cl之间的质量比为20∶8∶1.5、固液比为1∶5、浸出初始pH为7.5、浸出温度为70℃、浸出时间为120min时,石膏的浸出率达到90.0%;浸出锰渣主要物相含有CaCO_(3)、SiO_(2)、Ca_(2)Mn_(2)(OH)_(4)Si_(4)O_(11)·2H_(2)O、Mg_(5.0)Al_(6)Fe_(4)Si_(2.5)Al_(1.5)O_(10)(OH)_(8)以及KAl_(3)Si_(3)O_(10)(OH)_(2)等,其中浸出锰渣中MnO含量由未浸出前的7.45%提高到14.71%。转变规律表明,NH_(4)HCO_(3)与锰渣中的石膏反应转变成(NH_(4))_(2)SO_(4)和CaCO_(3),而NH_(4)Cl作为盐试剂可进一步促进石膏的溶解,从而提高石膏的浸出率。

Electrolytic manganese residue(EMR)has become a bottleneck hindering the development of electrolytic manganese industry,and the large amount of gypsum in EMR is the key to limit its resource utilization.Aiming at the problem of gypsum leaching from EMR,the effects of NH_(4)HCO_(3) and NH_(4)Cl dosage,initial pH of leaching,leaching time and leaching temperature on the transformation law of gypsum in manganese residue were studied.The results showed that the leaching efficiency of gypsum in EMR was 90.0%when the mass ratio of manganese residue to NH_(4)HCO_(3) and NH_(4)Cl was 20∶8∶1.5,the solid-liquid ratio was 1∶5,the initial pH of leaching was 7.5,the leaching temperature was 70℃and the leaching time was 120min.The main phases of the leaching EMR included CaCO_(3),SiO_(2),Ca_(2)Mn_(2)(OH)_(4)Si_(4)O_(11)·2H_(2)O,Mg_(5.0)Al_(6)Fe_(4)Si_(2.5)Al_(1.5)O_(10)(OH)_(8) and KAl_(3)Si_(3)O_(10)(OH)_(2),and the content of MnO in EMR increased from 7.45%to 14.71%after leaching.The transformation law of gypsum in EMR indicated that NH_(4)HCO_(3) reacted with gypsum in EMR to convert into(NH_(4))_(2)SO_(4) and CaCO_(3),and NH_(4)Cl as a salt reagent can further promote the dissolution of gypsum,and thus improving the leaching efficiency of gypsum.