Inorganic Chemicals Industry ›› 2023, Vol. 55 ›› Issue (11): 107-114.doi: 10.19964/j.issn.1006-4990.2023-0063

• Environment·Health·Safety • Previous Articles     Next Articles

Preparation of α-hemihydrate gypsum from phosphogypsum by flotation and atmospheric trans-crystallization in solution

LIU Chao1,2(), FAN Chuigang1,3, LIU Runguo1, YU Dongxue4, LI Songgeng1,2()   

  1. 1.State Key Lab of Multi-phase Complex Systems,Institute of Process Engineering,Chinese Academy of Sciences,Beijing 100190,China
    2.School of chemical Engineering,University of Chinese Academy of Sciences,Beijing 100049,China
    3.Zhongdan College,University of Chinese Academy of Sciences,Beijing 100049,China
    4.Innovation Driven Development Center of Sichuan Development and Reform Commission,Chengdu 610021,China
  • Received:2023-03-16 Online:2023-11-10 Published:2023-11-16
  • Contact: LI Songgeng E-mail:15235123962@163.com;sgli@ipe.ac.cn

Abstract:

In order to realize the high value utilization of phosphogypsum,froth flotation-atmospheric Na2SO4 solution crystallization method was used to convert phosphogypsum sampled from Hubei province into α-hemihydrate gypsum.The morphology,composition and mechanical strength of the product were characterized through various characterization methods(like SEM-EDS,XRF,XRD,FT-IR,TG-DSC,whiteness test and mechanical strength test).Experimental data revealed that the final product had uniform particle size with aspect ratio of 1.50±0.271.Whiteness and purity(based on CaSO4) of the product was found to be around 84.6% and 95%,respectively.Most of the Si,F and P impurities was removed during the treatment,and final impurity level met the requirement of Grade I phosphogypsum in the National Standard GB/T 23456—2018 as the raw material of gypsum building materials.The compressive and 2 h flexural strength of hardened body of the crystallized product were higher than 36.3 MPa and 7.7 MPa,respectively,which met the requirements of the relevant national and industrial standards for the mechanical strength grade of high strength gypsum.The research was illustrated that α-hemihydrate gypsum with high whiteness,high purity,and high mechanical strength could synthesize by the process,and could be considered as a potential option for phosphogypsum.

Key words: phosphogypsum, α-hemihydrate gypsum, flotation, saline solution, crystal modifier

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