| With the fast development of titanium sponge and titanium pigment by chlorination, the requirement of Ti-rich feedstock is becoming more and more. The total Ti-rich feedstock of applying for titanium pigment in the world accounted for 75% of material total for consumption, on the contrary, the total Ti-rich feedstock of applying for titanium pigment in China accounted for 7.5% of ilmenite consumed, and there is much gap compare to the level of overseas, which shows the great foreground in China. At present, the main method of producing Ti-rich feedstock in China is electric-furnace smelting, but the low level and technique of production, small dimensions, inefficiency, great pollution, high energy consumption, low stability of operation, which all have an harmful effect on the development of titanium technology.In this dissertation, the new preparation technology of Ti-rich feedstock from ilmenite concentrate is studied, and the prepared superior Ti-rich feedstock contains TiO2 more than 95%, MgO+CaO less than 1.2%, which is suitable feedstock for titanium sponge and titanium pigment by chlorination.we adopt ilmenite concentrate in some plcace of Yun Nan province. The ilmenite concentrate is composed of ilmenite phase, moreover, maghemite phase and limonite phase. The components, such as TiO2,FeO,Fe2O3,MgO,CaO,SiO2, don't exist independently, but disperse in the ilmenite concentrate, which will affect the result of roasting and leaching. According to the test, if the ilmenite is leached directly by sulfuric acid, the titanium will get to the liquor less. In order to improve the tatio of acidolysis, we have to pre process the ilmenite, and we get more better result of testing after the ilmenite concentrate and alkali are mixed and roasted.The analysis of thermodynamics indicates that the main components of ilmenite concentrate, such as TiO2, SiO2,Al2O3, can react with sodium carbonate when the temperature is more than 957K, and what's more, can react with sodium hydroxide when the temperature is less than 2000K. It shows that the reaction of ilmenite and alcali is viable.After orthogonal experiment, we get the feasible roasting condition:when ilmenite concentrate is mixed with sodium hydroxide, roasting temperature at 600℃, roasting time of 5h, the ratioio of sodium hydroxide and ilmenite of 1.8:1,there will be much more Na2TiO3 and Na2O·2Ti02, which will improve the ratio of acidolysis. The roasting product, after grinded to-200 mesh, will got much better rusult of acidolysis when the product is leached by the diluent of sulphuric acid of 98%, and the hightest ratio of 96%. The test indicates the feasible acidolysis condition:leaching temperature at 90℃, tatio of sulphuric acid and ilmenite concentrate of 3.84:1, sulphuric acid of 80%. The factors that affect hydrolysis of titanium solution are various, such as hydrolysis temperature, hydeolysis time, stirring rate, titanium solution concentration, F ratio, Fe/Ti ratio, the content of tervalent ferro, clarity and stability. The hydrolysis temperature, hydeolysis time, stirring rate are studied,and the feasible acidolysis condition:the feasible hydeolysis condition at 90℃, hydeolysis time of 4h, stirring rate of 70r/min.Through this time test, the new preparation technological line of Ti-rich feedstock from ilmenite concentrate is founded out:the titanium mixed with alcali is roasted in some temperature, which changes into get Na2TiO3 and Na2O·2TiO2; then the roasting product is leached by sulphuric acid at ordinary temperture and pressure; titanium solution is got after filtration; what'is more, the titanium solution is hydrolyzed, and the prepared superior Ti-rich feedstock contains TiO2 more than 95% is got after roasting the product of hydrolysis. |
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