Effect of ilmenite properties on synthetic rutile quality

Ilmenite (TiO2 > 52%) can be upgraded to synthetic rutile (TiO2 > 88%) using a reduction and leaching process. Australian ilmenites (FeTiO3) contain variable amounts of titanium dioxide, iron oxide and other impurities. Ilmenites from different deposits can have different physical and chemical properties that affect ilmenite reduction and the final TiO2 content in synthetic rutile (SR). The main aim of this study was to characterise feed ilmenites using a wide range of traditional and advanced analytical techniques and to determine the effects of feed properties on the quality of the SR. Three different ilmenite samples were upgraded to SR using a comparable ilmenite to coal ratio, heating rate, reduction temperature, holding time, cooling temperature and acid leaching parameters. Differential scanning calorimetry, thermogravimetric analysis, Brunauer-Emmett-Teller (BET) surface analysis and sizing analysis data indicated a difference in physical and surface properties among the samples. Head samples had a TiO(2 )content between 60% and 65% and Fe2O3 content between 25% and 34%. XRF assay by size data confirmed a variation in the content of TiO2, Fe2O3 and impurities among different size fractions. XRD phase analysis indicated the samples were composed of ilmenite, pseudorutile and rutile. SEM morphology studies revealed that ilmenite particle shapes were sub-angular, sub-rounded or rounded. The study found a linear relationship between the metallisation as a result of processing and feed BET surface area. Feed ilmenites with higher BET surface area and fewer impurities resulted in higher SR quality.