Study on Preparation of High Quality Titanium-rich Materials by Hydrochloric Acid Leaching of Panzhihua Titanium Slag

To deal with the small particle size of Panzhihua ilmenite,the processes of smelting slag with Panzhihua titanium concentrate as raw material followed by redox calcination modification and hydrochloric acid leaching were adopted to produce high quality of titanium-rich material,which provides high quality of raw materials for production of titanium dioxide by chlorination process. The experiments were conducted to determine the appropriate leaching process with the normal Ti-slag by investigating the effects of leaching pressure,additives and leaching methods on extraction efficiency of the main impurities M₃O₅ in Ti-slag which was redox modified referring to the calcination parameters for titanium concentrates modification.The results show that it is difficult to extract M₃O₅ by atmospheric pressure leaching and the addition of soluble chloride salts,ethanol and iron powder cannot efficiently improve the leaching ability of M₃O₅ in Ti-slag.Furthermore,the second stage leaching has little influence on leaching efficiency of Ti-slag.It is favorable to improve the extraction efficiency of M₃O₅ by pressure leaching or agitation leaching but qualified titanium-rich materials cannot be prepared by the mentioned methods.It is mainly attributed to a great amount of residual insoluble M₃O₅ with dense structure in the modified Ti-slag,leading to a poor reactive activity.Due to the fact that a smaller content of M₃O₅ remains in the low-grade Ti-slag with modification treatment,the hydrochloric acid leaching process coupled with external pressure and agitation was applied to the first stage of leaching using the low-grade Ti-slag with modification treatment as raw material,with leaching at 145℃ for 7 h,2:1 of liquid-solid ratio and 20% of HCl concentration.It is evidenced that the high quality titanium-rich materials with w_{TiO2> 93% and w∑(CaO+MgO)< 1. 5% can be obtained satisfying the requirements for raw materials of domestic fluidizing chlorination process.}