2016 Volume 56 Issue 10 Pages 1715-1722
The thermal decomposition of titanomagnetite-based ironsand, and the effects of ironsand addition on the formation of SFCA and SFCA-I iron ore sinter bonding phases, was investigated using in situ X-ray diffraction. Titanium incorporation into the SFCA and SFCA-I structures was investigated via phase equilibria experiments and subsequent ex situ characterisation. Increasing ironsand addition from 1.3 to 6.7 and to 13.8 mass% in an otherwise synthetic sinter mixture composition designed to form SFCA-I did not significantly affect the thermal stability range of SFCA-I (~1373–1523 K), nor did it significantly affect the maximum concentration of SFCA-I attained (42–46 mass%). The main effect of ironsand addition was a small reduction in the thermal stability range of another complex calcium-rich ferrite, γ-CFF. In comparison, increasing ironsand addition from 2.4 to 3.9 and to 11.6 mass% in an otherwise synthetic sinter mixture composition designed to form SFCA resulted in a decrease in the maximum SFCA-I concentration, from 30, to 24 and 16 mass%, respectively, with a corresponding increase in the concentration of SFCA (16, to 23 and 33 mass%). The phase equilibria studies revealed that SFCA can incorporate more titanium in its structure (up to 1.2 mass% TiO2) than SFCA-I (0.6 mass% TiO2). The ‘total SFCA’ (i.e. SFCA-I + SFCA) content decreased as the ironsand content increased, as well as there being a general shift to higher temperature of the total SFCA concentration curves. Such effects are likely to exert an influence on the physical properties of iron ore sinter, as well as affecting sintering fuel requirements.