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A green process for recovery of H 2 SO 4 and Fe 2 O 3 from FeSO 4 ·7H 2 O by modeling phase equilibrium of the Fe(П)– SO 4 2 − –H + –Cl – system
Author(s) -
Zhang Yan,
Li Zhibao,
Zeng Yan,
Demopoulos George P.
Publication year - 2017
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.15795
Subject(s) - calcination , sulfate , chemistry , ferrous , crystallization , nuclear chemistry , electrolyte , mineralogy , inorganic chemistry , catalysis , biochemistry , organic chemistry , electrode
Ferrous sulfate heptahydrate FeSO 4 ·7H 2 O is a major waste produced in titanium dioxide industry by the sulfate process and has caused heavy environmental problem. A new green process for the treatment of FeSO 4 ·7H 2 O was proposed to make use of iron source and recycle sulfate source as H 2 SO 4 . It was found that by adding concentrated HCl to the FeSO 4 solution, FeCl 2 ·4H 2 O was crystallized out, which was subsequently calcined to produce Fe 2 O 3 and HCl. Concentrated H 2 SO 4 solution (about 65 wt %) was obtained by evaporating the FeCl 2 ·4H 2 O‐saturated filtrate. To facilitate the process development and design, the solubilities of FeCl 2 ·4H 2 O in HCl, H 2 SO 4 , and HCl + H 2 SO 4 solutions were measured and the experimental data were regressed with both the mixed‐solvent electrolyte model and the electrolyte NRTL model. On the basis of the prediction of the optimum conditions for the crystallization of FeCl 2 ·4H 2 O, material balance of the new process was calculated. FeCl 2 ·4H 2 O and Fe 2 O 3 were obtained from a laboratory‐scale test with about 70% recovery of ferrous source for a single cycle, indicating the feasibility of the process. © 2017 American Institute of Chemical Engineers AIChE J , 63: 4549–4563, 2017