Inorganic Chemicals Industry ›› 2026, Vol. 58 ›› Issue (2): 83-91.

• Environment·Health·Safety • Previous Articles     Next Articles

Study on hydrothermal dissolution and crystallization behavior of phosphogypsum

ZHENG Ruikai1,2(), YI Yun1,2, LIU Qiumei3, YANG Lin1,4, CAO Jianxin1,4()   

  1. 1.School of Chemistry and Chemical Engineering,Guizhou University,Guiyang 550025,China
    2.Guizhou Key Laboratory for Green Chemical and Clean Energy Technology,Guiyang 550025,China
    3.Guizhou Institute of;Technology,Guiyang 550003,China
    4.Guizhou Provincial Engineering Research Center of;Efficient Utilization for Waster,Guiyang 550025,China
  • Received:2025-01-20 Online:2026-02-10 Published:2026-03-12
  • Contact: CAO Jianxin E-mail:912932787@qq.com;jxcao@gzu.edu.cn

Abstract:

The phase transformation and influencing factors during the dissolution-recrystallization process of α-hemihydrate gypsum(α-HH) prepared from dihydrate gypsum(DH) via hydrothermal synthesis under saturated vapor pressure conditions were investigated,providing a reference for the hydrothermal preparation of α-HH from phosphogypsum(PG).Various gypsum sources were employed to examine the effects of heating rate,composition,and pH on the phase transition process,with XRD and SEM used to analyze the crystal transformation.The results indicated that an optimal heating rate of 0.1 ℃/min was determined for the hydrothermal conversion of PG.Within the temperature range of 108~130 ℃,the solubility of CaSO4 in natural gypsum,washed PG,raw PG,and lime-modified PG generally exhibited an initial gradual increase followed by a decrease before stabilizing,with the phase transition occurring near 118 ℃.At the same holding temperature,raw PG demonstrated slower dissolution-recrystallization rate and lower conversion efficiency compared to natural gypsum and washed PG,whereas lime-modified PG exhibited dissolution-crystallization behavior similar to that of washed PG.Water-soluble impurities in PG were identified as the primary factor hindering the dissolution-recrystallization process. Pretreatment methods such as water washing or lime neutralization could modify the PG′s phase transition behavior to resemble that of natural gypsum.

Key words: phosphogypsum, α-hemihydrate gypsum, lime modification, solubility

CLC Number: