99/03497 The dissolution of titanium from an Australian bituminous coal with aqueous HF: Steel, K. M. et al. Proc. Annu. Int. Pittsburgh Coal Conf., [computer optical disk], 1998, 15, 1150–1160

Abstract

The mode of occurrence of Ti in Gordonstone Thermal Coal, an Australian bituminous coal, is investigated and the dissolution behavior of the Ti from the coal with aqueous HF is presented. A low temperature ashing procedure at 350 C is performed on the coal to isolate the mineral matter. X-ray diffraction analysis of the mineral residue identifies anatase (TiO{sub 2}), amongst other compounds. Leaching experiments performed on the mineral residue with aqueous HF, however, indicate that not all of the Ti in the mineral sample displays similar dissolution characteristics to that of anatase. It is postulated that an amorphous hydrated titania (TiO{sub 2} x H{sub 2}O) occurs in the mineral residue produced at 350 C, along with anatase, and that this titania is highly reactive toward acid. It is further proposed that this hydrated titania is the dominant Ti bearing mineral in the coal, that it dehydrates to anatase during ashing and that anatase may not occur in the coal to a large extent. Leaching experiments performed on the coal are consistent with the notion that, while the titania is reactive toward aqueous HF, the particles of titania are very fine and highly disseminated throughout the coal structure.