INORGANICCHEMICALSINDUSTRY ›› 2016, Vol. 48 ›› Issue (9): 51-.

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Removal of SO42- in high concentration orthophosphoric acid by crystallization

Liu Fei1,Li Tianxiang1,2,Xie Tian1,Shi Lianjun1   

  1. 1.Wengfu(Group) Co.,Ltd.,Fuquan 550501,China;2.School of Chemical Engineering,Guizhou University
  • Online:2016-09-10 Published:2016-09-18

Abstract: Anion SO42- in orthophosphoric acid  was removed by cooling crystallization method with the 98%(H3PO4,mass fraction) orthophosphoric acid got from the purification and concentration of industrial grade wet-process phosphoric acid as raw material.The influences of cooling rate,stirring speed,crystal growth substance dosage,and crystal maturing time on the removal effect were investigated.The optimum technological conditions were comfirmed as follows:the stirring speed was 300 r/min,the cooling rate was 1 ℃ per 15 min,the growth substance dosage was 5 g,and the crystal maturing was 1.5 h.Under the best process conditions,SO42- of orthophosphoric acid removal rate reached 82.1%,mass fraction of  SO42- less than 20 mg/kg, meeting the 85% quality requirement for SO42- of food grade phosphoric acid,and improved the added-value of products.At the same time,this method provided a feasible way for the production of orthophosphoric acid with low content of SO42-.

Key words: orthophosphoric acid;SO42-;crystallization, removal

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