SCI和EI收录∣中国化工学会会刊

›› 2017, Vol. 25 ›› Issue (6): 821-828.DOI: 10.1016/j.cjche.2016.10.007

• Materials and Product Engineering • Previous Articles    

Preparation of synthetic rutile via selective sulfation of ilmenite with (NH4)2SO4 followed by targeted removal of impurities

Weizao Liu, Xiaomei Wang, Zhenpu Lu, Hairong Yue, Bin Liang, Li Lü, Chun Li   

  1. College of Chemical Engineering, Sichuan University, Chengdu 610065, China
  • Received:2016-10-07 Revised:2016-10-18 Online:2017-08-02 Published:2017-06-28
  • Supported by:
    Supported by the National Key Projects for Fundamental Research and Development of China (2016YFB0600904).

Preparation of synthetic rutile via selective sulfation of ilmenite with (NH4)2SO4 followed by targeted removal of impurities

Weizao Liu, Xiaomei Wang, Zhenpu Lu, Hairong Yue, Bin Liang, Li Lü, Chun Li   

  1. College of Chemical Engineering, Sichuan University, Chengdu 610065, China
  • 通讯作者: Chun Li,E-mail address:lic@scu.edu.cn
  • 基金资助:
    Supported by the National Key Projects for Fundamental Research and Development of China (2016YFB0600904).

Abstract: This paper describes a novel, facile chemical pathway for preparing synthetic rutile from ilmenite. The pathway consists of two primary units, i.e., selectively sulfating ilmenite, which was realized via roasting ilmenite with (NH4)2SO4 followed by selective thermal decomposition of the sulfated ilmenite, and targeted leaching of the impurities. The effects of the process parameters were systematically investigated. The results showed that the optimum sulfation conditions were a mass ratio of (NH4)2SO4 to ilmenite of 14, temperature of 360℃, and time of 120 min with a sulfation ratio of~95%. The optimum thermal decomposition conditions were 480℃ in N2 atmosphere, and nearly all TiOSO4 were decomposed with co-decomposition of FeSO4 of 23%. For acid leaching, the optimum conditions were 2.5 wt% HCl, 98℃ and 120 min. Under those conditions, 94.2% iron was removed with a TiO2 dissolution loss <1%. For alkali leaching, 67% SiO2 was removed in 5 wt% NaOH at 102℃ for 1 h. A synthetic rutile with a TiO2 content >92 wt% and total MgO + CaO <1.5 wt% was obtained. Based on these results, a schematic flowsheet was proposed. Additionally, it was found that the decomposition of FeSO4 mixed with TiOSO4 under N2 was inhibited due to its oxidation to a higher thermal stability Fe2(SO4)3 by oxygen emitted from the decomposition of TiOSO4. At the same time, TiOSO4 decomposition was promoted due to the immediate in situ consumption of oxygen by FeSO4. The synergetic effect might be responsible for the enhanced selectivity of sulfated ilmenite thermal decomposition.

Key words: Synthetic rutile, Ilmenite, Titania, Ammonium sulfate, Thermal decomposition

摘要: This paper describes a novel, facile chemical pathway for preparing synthetic rutile from ilmenite. The pathway consists of two primary units, i.e., selectively sulfating ilmenite, which was realized via roasting ilmenite with (NH4)2SO4 followed by selective thermal decomposition of the sulfated ilmenite, and targeted leaching of the impurities. The effects of the process parameters were systematically investigated. The results showed that the optimum sulfation conditions were a mass ratio of (NH4)2SO4 to ilmenite of 14, temperature of 360℃, and time of 120 min with a sulfation ratio of~95%. The optimum thermal decomposition conditions were 480℃ in N2 atmosphere, and nearly all TiOSO4 were decomposed with co-decomposition of FeSO4 of 23%. For acid leaching, the optimum conditions were 2.5 wt% HCl, 98℃ and 120 min. Under those conditions, 94.2% iron was removed with a TiO2 dissolution loss <1%. For alkali leaching, 67% SiO2 was removed in 5 wt% NaOH at 102℃ for 1 h. A synthetic rutile with a TiO2 content >92 wt% and total MgO + CaO <1.5 wt% was obtained. Based on these results, a schematic flowsheet was proposed. Additionally, it was found that the decomposition of FeSO4 mixed with TiOSO4 under N2 was inhibited due to its oxidation to a higher thermal stability Fe2(SO4)3 by oxygen emitted from the decomposition of TiOSO4. At the same time, TiOSO4 decomposition was promoted due to the immediate in situ consumption of oxygen by FeSO4. The synergetic effect might be responsible for the enhanced selectivity of sulfated ilmenite thermal decomposition.

关键词: Synthetic rutile, Ilmenite, Titania, Ammonium sulfate, Thermal decomposition