1990 Volume 30 Issue 9 Pages 704-713
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 made 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 functions of crystalization time, temperature and flux compositions. In the experiment that the crystallized fine α-Fe2O3 particles were dissolved by dilute HCl 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.
