Separation Of Impurity From Clean Production Progress Of Titanium Dioxide In Titanium Slag With Molten Salt

Titanium dioxide(TiO₂) is important basic raw materials in chemical and metallurgical industries.So,developing a new,green,high efficiency-clean progress of titanium metallurgical technology is of great realistic and social meanings.On the bases of former researches,a new clean production process of titanium dioxide by decomposition titanium slag with high reactivity NaOH molten salt(MS) was proposed in the present paper.The aim of this new process is to eliminate the pollution at the source and to fully utilize valuable compounds in titanium resources.The main points and results are as follows:(1) A reaction system of titanium slag and molten NaOH was established. The process parameters of the decomposing titanium slag in NaOH molten salt medium were optimized,and the MS reaction mechanism of the impurity oxides in titanium slag was discussed.The results showed that the conversion ratio of titanium was above 96%under the optimum conditions,and the reaction product was Na₂TiO₃.(2) MS reaction products were treateded by three-stage countercurrent wash.After three-stage countercurrent washing of MS reaction products,the Na⁺ and impurities of Cr,Al,Mn,Si were leached to the alkaline solution, while titanium and impurities of Fe,Ca,Mg remained in the solid intermediate,thus,titanium was separated from impurities selectively.The lye obtained could be retruned back to the decomposition process and recycled by further purification,evaporation and enrichment.(3) Impurities were separated from NaOH alkaline solution.The effect of additives quantity and reaction temperature for separation of Mn,Al and Si from the recycled alkaline solution were investigated.The results showed that approximately 99.7%of Mn(â…¥) in the recycled lye could be removed in the optimal conditions,and the concentrations of Al and Si could be reduced to be 1 and 0.2_g·L^-1 respectively.(4) The acid treatment process was optimized.The solid intermediate, obtained from the MS product of Dongjia titanium slag and NaOH molten salt after wash,was treated by the sulfate and oxalate solution.The optimum reaction conditions were obtained.The results showed that titanium dioxide with purity of over 95%could be obtained.