Purification of Roasted Iron Oxide Product from Waste Pickling Liquor by Glass-ceramic Method

The experiment has been carried out for the purification of α-Fe₂O₃by the glass-ceramic method. After melting the roasted product of the waste pickling liquor with Na₂O-B₂O₃fluxes having the Na₂O/B₂O₃(mole ratio) = 1/2-1/5, the glass samples obtained by rapid quenching crystallized at temperatures ranging from 550 to 1 000°C for 55 s to 24 h. The separation of the precipitated α-Fe₂O₃from the flux was made by wet chemical treatment with water and dilute HCI solution, after which high purity and fine α-Fe₂O₃crystals were obtained. The impurity contents, Fe yield, and crystal shape and size have been investigated as functions of crystallization time, temperature and flux compositions. In the experiment that the crystallized fine α-Fe₂O₃particles were dissolved by dilute HCI solution in stepwise manner, the analysis of impurities in each stage shows that the contents of Si, Na, B, Ca and Al were enriched on the crystal surface.