Behaviour and characterization of hematite process for iron removal in hydrometallurgical production

The separation of zinc and iron is essential in hydrometallurgical processes, especially for treating high-iron sphalerite. The hematite precipitation process for removing iron is an effective way to achieve the high-efficiency separation of zinc and iron. The authors studied the effect of temperature and time on the precipitation behaviour and characterised the precipitation products through X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and chemical analysis. The hematite precipitate contained more than 50% iron, less than 0.5% zinc, 0.1% arsenic and 5% sulfur; more than 95% K, 50% Na and 50%-60% F were co-precipitated, and less than 1% Zn, Mg, Mn and Cl remained in the residue. Because of the uncontrolled supersaturation conditions, jarosite and goethite were generated. Extension of the reaction time and increasing the reaction temperature enabled conversion of most of the goethite and sodium jarosite to hematite during the hematite precipitation process.