| Yunnan province, where about55.61millions tons of titanium ore have been explored and more than400thousands tons of titanium concentrate are produced every year, is one of the significant producing areas of titanium ore in China. In order to accelerate mining of titanium ore in Yunnan province, a local corporation developed relating projects. A significant one was firstly importing a titanium slag production line, the main equipment of which was a30MVA closed DC arc furnace, into China. The furnace, which could produce titanium slag with high quality, showed several advantages including a simple work flow, low energy consumption, high production efficiency and furnace gas easy to reclaim. The furnace produced4000to5000tons of titanium slag smoke dust, by test, which including40%TiO2, with a high value.In order to economically reclaim smoke dust produced by this furnace, in this paper, researches were done on it. Elementary composition, phase composition and particle size distribution of the smoke dust were separately detected by elementary analysis, X-ray diffraction analysis and grain size analysis. The results showed the main ingredients of it were titanium slag and unreacted ilmenite, where TiO2took38%and iron oxide took51%. For purpose of extracting the38%of TiO2and eliminating impurities including iron oxides, the mechanisms of atmospheric pressure leaching of titanium slag smoke dust by hydrochloric acid and sodium salt roasting-leaching-calcining were studied and exploratory experiments were done on atmospheric pressure leaching by hydrochloric acid, sodium salt roasting-leaching-calcining and pelletizing of titanium slag smoke dust.The researches on acid leaching revealed, when the acid leaching temperature was120℃, the particle size of smoke dust was under200mesh, the leaching time was2.5hours, liquid-solid ratio was10to1and the acid used to leach was hydrochloric, both of recovery and grade of TiO2in the leaching residue were the highest. However, though iron oxides, calcium oxides and magnesium oxides could be removed by reaction with hydrochloric, ferrum in ilmenite could hardly be eliminated by acid leaching because of its dense structure, therefore, by acid leaching, TiO2grade in leaching residue could only be raised to67%。The researches on sodium salt roasting-leaching-calcining showed, both of solid solution structure of ilmenite and anosovite structure of titanium slag could be destroyed by sodium salt roasting, thus acid leaching of smoke dust after sodium salt roasting could remove more impurities than acid leaching directly. Optimum condition of roasting were separately roasting temperature at925℃, roasting time of2hours, mass ratio of Na2CO3to titanium slag smoke dust at1to2.5. Optimum condition of acid leaching were separately acid leaching of two-stage process, leaching temperature at120℃, particle size under200mesh, leaching time of2.5hours, liquid-solid ration at10to1and leaching by hydrochloric acid. Optimum condition of calcining were separately calcining temperature at900℃and calcining time of1hour. Under the optimum conditions, TiO2in calcined leaching residue could be raised to78%.Researches on pelletizing of titanium slag smoke dust suggested that pellets made by disc pelletizer using mix of titanium slag smoke dust and adhesive could meet the electric furnace smelting requirements about particle size and strength, nevertheless, adhesive would bring impurities into smoke dust. Therefore, more works are still being done on studying the mechanisms of pelletizing. |
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