Study On Preparing Ti-rich Feedstock By Selective Leaching The Modified Titanium Slag With Hydrochloric Acid Solution

In this dissertation, the technology of the preparation of Ti-rich feedstock with Panzhihua Iron and Steel Plant titanium slag has been studied. According to the special features of the modified titanium slag, the technical process of preparing superior Ti-rich feedstock by selective Leaching the modified Titanium Slag with HC1 was proposed. The prepared superior Ti-rich feedstock contained 91.2%TiO2, CaO+MgO<1.5, and it was suitable feedstock for chloride pigment.The treated titanium slag was composed of rutile phase, ilmenite phase and glassy silicate phase by X- RD and SEM. Rutile is not dissolve in hydrochloric acid solution, but ilmenite phase and glassy silicate phase are dissolve. The content of TiO2 in the leached titanium slag was improved by selective leaching with hydrochloric acid solution.Between the temperature of 25℃ and 140℃, the analysis of thermodynamics indicated that the main components of the treated titanium slag, such as MgTi2O5, FeTiO3, MgO, FeO, Al2O3, CaO and Fe can react with hydrochloric acid solution. The components do not exist independently, but disperse in the treated titanium slag. The experiment results showed that the leaching reaction velocity is slow and the leached slag is not suitable feedstock for chloride pigment.The tests indicate that the kinetics of selective leaching the modified titanium slag with hydrochloric acid complied with the shrinking un-reacted core model without solid product. By investigating the effects of hydrochloric acid concentration, temperature and size of ore on the leaching rate, it was suggested that the leaching of modified titanium slag with hydrochloric acid solution is one of the first order reaction. Its activation energy is 62.56kJ/mol, indicating that the chemical reaction was the rate controlling step. Agitating has no effect on the leaching velocity.The effects of hydrochloric acid concentration, temperature, leaching time and the ratio of ore and acid on the leaching rate were investigated. The rhombic and condition experiments indicate that the principal effect factor on the leaching rate is hydrochloric acid concentration, the second factor is temperature, and the last factoris leaching time and the ratio of ore and acid. It is the best leaching conditions that the hydrochloric acid concentration is 20%, leaching temperature is 145℃, leaching time is 7h, and the ratio of ore and acid is 1:2. The prepared superior Ti-rich feedstock contains 91.2%TiO2, CaO+MgO<1.5, and it is composed of rutile and a minor account of silicon dioxide.