Aspects of the extraction of titanium dioxide from ilmenite and titaniferous slag

Abstract

Phase separation in lithium borate glasses has been studied by scanning electron microscopy and differential thermal analysis. Scanning electron micrographs were taken of the etched surfaces of 5, 10, 15 and 20 mol% Li2O.B2O3 glasses. Glass transition temperatures were calculated from DTA experiments over the glass forming range. Optical basicities for Cs2O + B2O3 and Li2O + B2O3 glasses have been measured as a function of glass composition, using Tl(I), Pb(II) and Bi(III) probe ions. Optical basicities for pure B2O3 and water were also measured using the three probe ions. Extraction of TiO2 from ilmenite using Li2O.xB2O3 glasses (where x = 2, 4 – 8) has been investigated. Quantitative determinations of the TiO2 content of the water leached products were done using X-ray powder diffractometry (the Matrix-Flushing Method). Further extraction with 9 mol dm-3 H2SO4 yielded rutile which was 86% pure. Solvent extraction of titanium from ilmenite was investigated using different compositions of the Na2O-B2O3-NaCl glass-salt (two phase) system. Both glass and salt phases enriched with titanium, relative to the titanium content of ilmenite, were obtained. Chlorination of ilmenite and titaniferous slag in a 50 mol% NaCl/50 mol% KCl fused salt medium was investigated with different carbonaceous materials. The TiO2 produced by hydrolysis of the TiCl4 generated was the rutile phase. A possible mechanism using thermodynamic data is discussed. High temperature reactions between ilmenite and K2CO3 were studied. The resulting complex products were leached with either water or concentrated HCl or 9 mol% dm-3 H2SO4. Possible components of the products have been identified by X-ray powder diffraction.