| Titanium dioxide is a significant inorganic chemical raw material because of its good chemical resistance and thermal stability, excellent optical, mechanical and electrical properties and non-toxic harmless, it is widely used in cosmetics, paint, plastics, transducer, a supporting materials and catalysis. Among them, the pigment grade titanium dioxide (Tai Bai) is the best white pigment, accounting for 80% of the amount of white pigment, and 80% of titanium resources are used for the production of Tai Bai.The reserves of titanium resources in China is extremely rich and in the forefront of the world. More than 90% titanium resources exsit in the form of vanadium titanium magnetite. For the use of vanadium titanium magnetite, the utilization ratio of titanium and vanadium from vanadium-bearing titanomagnetite is low by the traditional blast furnace method, which makes it difficult to achieve the comprehensive utilization of valuable element. Therefore, this method leads a waste of resources and low economic benefits; The process of reduction and melting can make full use of Fe and V through vanadium-bearing titanomagnetite rotary furnace, rotary hearth furnace, smelting furnace in recent years. But Ti was stable and it was difficult to be ultilized in melting slag; The Chinese academy of sciences institute of process engineering proposed a new process, which made the iron by reduction and vanadium by sodium extracted. This process dealed with the poor vanadium titanium magnetic of the west of Liaoning Province and ultilized the resource of titanium efficiently. As the roasting slag from the new technology was difficult to handle, the mineralogical characteristics of roasting slag and many methods to deal with had been studied. Then, the new technology of direct extraction of Ti resources under high pressure with hydrochloric acid had been put forward in this paper. The influence of temperature, time, ratio of solid to liquid, acid concentration and other conditions of new technology on extraction of Ti in the acid solution were also considered. The apparent activation energy of the reaction has been calculated according to the solid product layer diffusion control dynamic equation model of the 1+2(1-x)-3(l-x)2/3=kland Arrhenius equation.The hydrolysis process of simulated hydrochloric acid titanium solution, preliminary mechanism and the effect of hydrolysis conditions on the quality of TiO2 were studied.(1) The mineralogy characteristics of reductively roasted titaniferous slag was studied and the slag was tried to deal with by many different methods. The results showed that the extraction rate of Ti were low by sulfuric acid method of one step and two step. The removal rate of Si could reach 90% and the removal rate of Ti was less than 5%, but the concentration of NaOH was too high to get economic benefits. Therefore, a new process of acid leaching process under pressure was proposed.(2) The conditions of the new process on leaching rate of Ti were studied. The optimized conditions of leaching process were as follows:Leaching 2 h with 30wt% HCl at 120℃ under ratio of liquid to solid 8:1. According to the dynamics equations of layer diffusion control model of solid product and the Arrhenius equation, kinetic equation of leaching in hydrochloric acid system at atmospheric pressure can be obtained with the effect of reaction temperature on leaching rate of Ti and Ca, which is 1+2(1-x)-3(1-x)2/3=11.4e-31.2IRT-t. Meanwhile its reaction activation energy Ea=-31.2 kJ/(mol.K).(3) The Ti4+existed in the form of compound clusters ((Ti2O2)(H2O)4CI4 and Ti(OH)2CI2) based on the DFT calculation and Raman spectrum. The nuclear energy was 19.46 kJ/mol by Gibbs free energy equations (△G=-RT(21n[H+]-ln[Ti4+])+Srsl) and the relationship between the particle sizes of H2TiO3 and concentration of Ti4+and HCl. |
PDF Full Text Request