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-Fe2O3 by the glass-ceramic method. After melting the roasted product of the waste pickling liquor with Na2O-B2O3 fluxes 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-Fe2O3 from the flux was conducted by wet chemical treatment with water and dilute HCl solution, after which high purity and fine α-Fe2O3 crystals were obtained. The impurity contents, Fe yield, and crystal shape and size have been investigated as a function of crystallization time, temperature and flux compositions. Dissolution of the crystallized fine α-Fe2O3 particles by dilute HCl solution in stepwise manner, and subsequent analysis of impurities in each stage showed that the contents of Si, Na, B, Ca, and Al were enriched on the crystal surface.