Inorganic Chemicals Industry ›› 2022, Vol. 54 ›› Issue (11): 104-111.doi: 10.19964/j.issn.1006-4990.2022-0075

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Research on deep purification process of glauberite gypsum

YIN Huibin(),LI Jun(),ZHENG Zhuochao   

  1. School of Chemical Engineering,Sichuan University,Chengdu 610065,China
  • Received:2022-02-23 Online:2022-11-10 Published:2022-11-23
  • Contact: LI Jun E-mail:2606991612@qq.com;lijunlab@163.com

Abstract:

Glauberite gypsum is the by-product tailings produced by leaching sodium sulfate in the industry.Compared with industrial by-product gypsum such as desulfurized gypsum and phosphogypsum,it has higher impurity content,lower purity and utilization value.Glauberite gypsum was purified by acid leaching-recrystallization process,the acid-soluble impurities in Glauberite gypsum were removed by acid leaching and dihydrate calcium sulfate(DH) was converted into anhydrous calcium sulfate(AH).Then hydration conditions were controlled to hydrate AH into large-size DH crystals separated from small-sized acid-insoluble impurities to obtain high-purity dihydrate gypsum.The effects of sulfuric acid concentration,hydration activator,liquid-solid ratio and reaction time on purified gypsum were studied.The research results showed that under normal pressure,when the mass fraction of sulfuric acid pickling solution was 35%,the reaction temperature was 80 ℃,the solid-liquid ratio of gypsum and sulfuric acid solution was 1∶5,and the pickling time was 2 h,it could effectively remove acid-soluble impurities in glauberite gypsum.When mass fraction of hydrate sulfuric acid was 5%,mass fraction of potassium sulfate was 1.74%,reaction temperature was 25 ℃,solid-liquid ratio was 1∶6,aging time was 18 h,it could effectively remove acid-insoluble impurities in glauberite gypsum,and the purity of purified gypsum could reach more than 97%.

Key words: glauberite gypsum, gypsum purification, recrystallization

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