Dissolution Of TiO₂in Aqueous Solution After Heat Treatment Of Titanium-bearing Blast Furnace Slag

Titanium-bearing blast furnace slags heap of a large number of abandoned not only waste resources but also pollute the environment. How to effectively deal with them has become a pressing issue. This paper aims at putting forward the optimum condition for Ti-dissolution by utilizing (NH4)2SO4heat melting method which has Titanium-bearing blast furnace slag as the raw material. Add such flux as K2SO4or KHSO4in different promotion in the reaction mixture. There will be such portions as Ti,Mg and Fe are extracted through a series chemical process like fusion reaction, leaching and filtering. Then the content and dissolution rate of water-soluble Ti,Mg and Fe will be detected and calculated through chemical analytical procedure. At the same time, the influence of various technical condition on dissolution rate will be observed through single-factor impact analysis experiment to put forward the optimum condition for Ti-dissolution. By adjusting the pH value of Ti liquid filtered from the fusion reaction mixture and adding chelant to completely hydrolyze the Ti liquid to get high purity TiO2. The recycling flux which is the product of dealing with the hydrolysis of Ti liquid filtrate took place of the original flux in treating Titanium-bearing blast furnace slag, dissolution rate of Ti and Fe is the focus.The experiment result shows that the optimum technical condition for Ti-dissolution from slow cooled titanium-bearing blast furnace slag is:mix the slow cooling slag,(NH4)2SO4and K2SO4according to a certain mass ratio, then heat to380℃and stay for36mins, the dissolution rate of Ti is75.9%; mix the slow cooling slag,(NH4)2SO4and KHSO4according to a certain mass ratio, then heat to410℃and stay for36mins, the dissolution rate of Ti is77.4%. While the optimum technical condition for Ti-dissolution from water-quenched titanium-bearing blast furnace slag is:mix the water-quenched slag,(NH4)2SO4and K2SO4according to a certain mass ratio, then heat to410℃and stay for36mins, the dissolution rate of Ti is98.0%; mix the water-quenched slag,(NH4)2SO4and KHSO4according to a certain mass ratio, then heat to350℃and stay for36mins, the dissolution rate of Ti is99.3%. In the study of precipitation TiO2, the pH of Ti liquid has a great influence on the precipitation of Ti. The greater pH, the more complete precipitation of titanium. However, the high pH will result in coprecipitation of Fe and Al, which will reduce the purity of TiO2. Therefore, the pH value should be less than3.16. Add EDTA, aminoacetic acid and citric acid to the titanium liquid to chelate Fe first, and then control the pH for precipitation of Ti. The result shows that aminoacetic acid has no influence on the precipitation of Ti、Fe and Al; while EDTA can can effectively inhabitit the precipitation of A1and Fe, which can separate Ti, Fe and Al. When the pH value is increased, the precipitation of Ti is slightly increased; however the adding of citric acid can increase the precipitation of Ti. When pH value is over3.00, citric acid will chelate Ti and have no influence on the precipitation of Fe and Al. As a result, there will be iron and aluminum oxide in the TiO2production.The result shows that Ti dissolution rate of Titanium-bearing blast furnace slag under the optimum condition presents a good reproducibility. After the processing of hydrolyzed Ti liquid, the recycling flux can replace original flux to treat Titanium-bearing blast furnace slag, the dissolution rate of Ti and Fe is96.1%and91.5%respectively.