| Titanium dioxide,widely used in metallurgy,electronics,paint,plastics,paper,printing ink,chemical fiber,rubber,cosmetics and other industries,has played an important role in the modern industry.The current methods which were mainly used to produce high purity titanium dioxide are the hydrolysis of titanium tetrachloride,hydrolysis of alkoxide,sol-gel method and chlorination method respectively.But these methods have such problems as the higher requirement for the raw materials,for example chlorination method requires that the content of Mg and Ca in the raw materials is low while the content of titanium dioxide is more than 90%,as well as the production costs than that of the traditional sulfuric acid method.However the traditional method would generate substantial waste and finally result in a significant impact on the environment.So it is very important to explore a clean production process of titanium dioxide with a low reqirement for the raw materials and low production cost.In this paper,cheap and essily abtained low-grade titanium slag was taken as raw materials to produce high quality titanium dioxide by the method of roasting and then acid leaching.This paper aims to explore a feasible technological route of high quality titanium dioxide and to provide reference for the industrialization of high quality titanium dioxide.The content of TiO2 in titanium slag was 75.56%,of which the major impurities were Fe,Ca,Al,Si,especially,CaO+MgO content was up to 5.63%.The main phase was anosovite and it also contained some silicate.The surface of titanium slag was smooth and there was not crack and depression on the surface.The method of sodium carbonate roasting-sulfuric acid leaching was used to remove the impurity.The removing impurity process of slag by roasting-sulfuric acid leaching were studied and determined.The results showed that the titanium slag was roasted at the conditions of the ratio of sodium carbonate to titanium slag of 4/7,the temperature of 900℃for 80 minmunites and then the roasted product was leached by sulfuric acid with the conditions of the acid concentration of 20wt%,recation temperature of 90 ℃,leaching time of 4 h and ratio to liquid of 9:1.The impurities can be partly removed and the titanium can be enriched effectively.Leaching slag was leached by the sulfuric acid to produce titanic solution.The results showed that under the condition of the concentration of sulfuric acid of 40 vol%,the reaction temperature of 90℃,and acid solution time of 2.5 h,titanium leaching rate reached 95.12%,and compared with the traditional method,the sulfate acid concentration and temperature were greatly reduced.Metatitanic acid was made by the method of added self-generating crystal seeds and then hydrolysis.The conditions was oxalic acid concentration of 3wt%,stirring speed of 150rpm,the volume ratio of titanium solution volume to oxalic acid of 1:1,the reaction temperature of 95℃ and the hydrolysis time of 2 h.Under the conditions the hydrolysis rate reached 94.95%.H2TiO3,washed by DC acidification of water and pure water was rasted at the temperature of 850℃ for 1h and finally high purity pure TiO2 of 99.95%could be obtioned.Polyethylene glycol was used as additive to inhibit the growth of crystal nucleus and then nano scale TiO2 can be produced.The leaching and hydrolysis waste acid would be used as raw materials to produce ammonioiarosite by air oxidation.Heating unde alkaline conditions,the ammonium jarosite was broken down into iron oxide to recover iron.Research has showed that this process can prepare high quality ferric oxide and provides a new idea for the treatment of waste acid containing iron. |
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