Behavior and mechanism of iron mineralization precipitation in ZnSO4-FeSO4 solution at 120-180 ℃
In order to solve the problem that the mechanism and the phase transition behavior of Fe2+mineralization precipitation process of high zinc concentration iron-containing solution containing Zn2+130 g/L and Fe2+15 g/L in zinc hydrometallurgy are unclear,the mineralization precipitation behavior of ferrous ion from zinc hydrometallurgical ZnSO4-FeSO4 solution at 120-180 ℃ was investigated.The effect of reaction temperature,oxygen partial pressure,agitation speed and reaction time on the mineralization precipitation behavior of ferrous ion was analyzed.The results indicate that the reasonable mineralization conditions as follows:reaction temperature of 150 ℃,oxygen partial pressure of 0.3-0.4 MPa,agitation speed of 500 r/min and reaction time of 180 min.The iron removal efficiency is 91.33％ at the optimal condition.The concentration of Fe2+and total Fe in the solution after Fe precipitation decreases to 0.10 g/L and 1.30 g/L,respectively.At the same time,high-grade hematite containing 61.35％ Fe,1.01％ Zn and 1.61％ S can be produced.XRD and SEM characterization shows that the phase composition of mineralization product consists of goethite and oxyhydroxides at below 130 ℃,and mainly of hematite at above 130 ℃.Fe2+mineralization precipitation involves the reaction process of oxidation,hydrolysis,dehydration and dehydroxylation.XPS analysis shows that the mineralization product is oxyhydroxides (Fe2-x/3(OH)xO3-x),with incomplete dehydration (H2O) and dehydroxylation (—OH) leading to Fe vacancies.Zn2+exists in the crystal of mineralization products through interstitial atom or atomic substitution,and coordinates with O2-.Sulfate ions coordinate with Fe(Ⅲ) on the crystal surface (FeSO4+) and exist in the form of sulfate (Fe2(SO4)3).Sulfate ions are almost uniformly incorporated into mineral particles and distributed evenly on the crystal surface and inner.
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