Panzhihua Ilmenite Preparation Of High-grade New Technology Research, Rich Titanium Material

The Panxi area in China is rich in titanium resource, and stands first on the globe in terms of ilmenite reserves. However, the Panxi ilmenite concentrate which is a rock-type origin presents a compact structure of crystal, and contains low grade TiO2 and high contents of non-ferrous impurities, especially high contents of MgO and CaO. Traditional production methods of rich titanium materials have limitations because of those characteristics. Integrated the advantages of hydrochloric acid leaching process and oxidation-reduction pretreatment, a new technology flow for the preparation of synthetic rutile which meet the requirements of chlorination process has been proposed involving the following operations:oxidation, reduction, mechanical activation, hydrochloric acid leaching at ambient pressure.The oxidation and reduction of untreated ilmenite concentrate and mechanically activated ilmenite concentrate were investigated using XRD, SEM, EDS and particle size analysis, etc. The results show that with the increase of oxidation temperature, the Panxi ilmenite concentrate was first oxidized to hematite, rutile and pseudorutile, and then the pseudorutile decomposed to hematite and rutile which subsequently combined to form pseudobrookite. Fe in Panxi ilmenite concentrate migrated to the surface of mineral particles during the oxidation. The morphology of Panxi ilmenite concentrate can be changed in different extent with the change of oxidation temperature during the oxidation-reduction treatment. The initial oxidation temperature of ilmenite concentrate can be decreased to some extent by mechanical activation, but it has almost no influence on the reaction temperature of pseudorutile decompose to hematite and rutile, as well as hematite and rutile combine to form pseudobrookite.The experimental results of hydrochloric acid leaching behaviour of different treated ilmenite concentrates indicated that both of mechanical activation and oxidation-reduction treatment not only significantly accelerated the extraction of Fe, Ca and Mg from Panxi ilmenite concentrate, but also apparently put forward the initial hydrolysis time of titanium ions in hydrochloric acid solution. In addition, oxidation-reduction treatment can obviously decrease the Ti extraction in hydrochloric acid solution. The formation of pseudobrookite by oxidizing at 900℃is more favorable to upgrade Panxi ilmenite concentrate to synthetic rutile due to the complete destruction of the ilmenite crystalline structure.Synthetic rutile which was successfully prepared through the the process of "oxidation-reduction-mechanical activation-hydrochloric acid leaching" contains 90.50 wt.% TiO2 and 1.37 wt.% total iron as well as combined CaO and MgO of 1.00 wt.%. The results demonstrate that this process can excellently upgrade ilmenite concentrate with high content of gangue like Panxi ilmenite concentrate into synthetic rutile which meets the requirements of chlorination process. The optimum oxidation and reduction conditions were as follows:oxidized at 900℃in the presence of oxygen for 15 min, reduced at 750℃by hydrogen for 30 min.The kinetics results show that the leaching curves for untreated ilmenite concentrate, mechanically activated ilmenite concentrate and oxidized-reduced ilmenite concentrate follow the kinetic model of the shrinking core model, with diffusion through the solid product of the reaction as the controlling stage. Mechanical activation and oxidation-reduction treatment can depress the apparent activation energy for the leaching reaction of Fe from 47.40 kJ/mol to 42.60 kJ/mol and 27.05 kJ/mol, respectively.