SCI和EI收录∣中国化工学会会刊

Chinese Journal of Chemical Engineering ›› 2020, Vol. 28 ›› Issue (4): 1162-1170.DOI: 10.1016/j.cjche.2020.02.009

• Energy, Resources and Environmental Technology • Previous Articles     Next Articles

Chemical dehydration coupling multi-effect evaporation to treat waste sulfuric acid in titanium dioxide production process

Hongyin Pang1,2, Ruifang Lu1, Tao Zhang2, Li Lü2, Yanxiao Chen2, Shengwei Tang2   

  1. 1 State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization, Panzhihua 617000, China;
    2 School of Chemical Engineering, Sichuan University, Chengdu 610065, China
  • Received:2019-10-29 Revised:2020-02-04 Online:2020-07-27 Published:2020-04-28
  • Contact: Shengwei Tang
  • Supported by:
    The authors gratefully acknowledge the State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization of China for its financial support. The authors are also grateful for the financial support of National Natural Science Foundation of China (Grant No. 21576168) & Science and Technology Cooperation Fund of Sichuan University-Panzhihua (No: 2018CDPZH-23-SCU).

Chemical dehydration coupling multi-effect evaporation to treat waste sulfuric acid in titanium dioxide production process

Hongyin Pang1,2, Ruifang Lu1, Tao Zhang2, Li Lü2, Yanxiao Chen2, Shengwei Tang2   

  1. 1 State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization, Panzhihua 617000, China;
    2 School of Chemical Engineering, Sichuan University, Chengdu 610065, China
  • 通讯作者: Shengwei Tang
  • 基金资助:
    The authors gratefully acknowledge the State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization of China for its financial support. The authors are also grateful for the financial support of National Natural Science Foundation of China (Grant No. 21576168) & Science and Technology Cooperation Fund of Sichuan University-Panzhihua (No: 2018CDPZH-23-SCU).

Abstract: In order to concentrate the diluted sulfuric acid from the titanium dioxide (TiO2) production of sulphate process, a new concentration process was proposed by coupling chemical dehydration and multi-effect evaporation. The ferrous sulfate monohydrate (FeSO4·H2O), as the dehydrant, was added to the diluted sulfuric acid to form ferrous sulfate heptahydrate (FeSO4·7H2O) according to the H2SO4-FeSO4-H2O phase diagrams, which partially removes the water. This process was named as Chemical Dehydration Process. The residual water was further removed by two-effect evaporation and finally 70 wt% sulfuric acid was obtained. The FeSO4·H2O can be regenerated through drying and dehydration of FeSO4·7H2O. The results show that FeSO4·H2O is the most suitable dehydrant, the optimal reaction time of chemical dehydration process is 30 min, and low temperature is favorable for the dehydration reaction. 45.17% of the entire removed water can be removed by chemical dehydration from the diluted sulfuric acid. This chemical dehydration process is also energy efficient with 24.76% saving compared with the direct evaporation process. Furthermore, 51.21% of the FeSO4 dissolved originally in the diluted sulfuric acid are precipitated out during the chemical dehydration, which greatly reduces the solid precipitation and effectively alleviates the scaling in the subsequent multi-effect evaporation process.

Key words: Chemical dehydration, Multi-effect evaporation, Sulfuric acid, Titanium

摘要: In order to concentrate the diluted sulfuric acid from the titanium dioxide (TiO2) production of sulphate process, a new concentration process was proposed by coupling chemical dehydration and multi-effect evaporation. The ferrous sulfate monohydrate (FeSO4·H2O), as the dehydrant, was added to the diluted sulfuric acid to form ferrous sulfate heptahydrate (FeSO4·7H2O) according to the H2SO4-FeSO4-H2O phase diagrams, which partially removes the water. This process was named as Chemical Dehydration Process. The residual water was further removed by two-effect evaporation and finally 70 wt% sulfuric acid was obtained. The FeSO4·H2O can be regenerated through drying and dehydration of FeSO4·7H2O. The results show that FeSO4·H2O is the most suitable dehydrant, the optimal reaction time of chemical dehydration process is 30 min, and low temperature is favorable for the dehydration reaction. 45.17% of the entire removed water can be removed by chemical dehydration from the diluted sulfuric acid. This chemical dehydration process is also energy efficient with 24.76% saving compared with the direct evaporation process. Furthermore, 51.21% of the FeSO4 dissolved originally in the diluted sulfuric acid are precipitated out during the chemical dehydration, which greatly reduces the solid precipitation and effectively alleviates the scaling in the subsequent multi-effect evaporation process.

关键词: Chemical dehydration, Multi-effect evaporation, Sulfuric acid, Titanium