Production Process UGS Slag

Nowadays, Titanium dioxide is the best-quality pigment in the world, widely used in coatings, plastic, paper and other industries. The industrial production of Titanium dioxide include sulphate process and chloride process, boiling chloride process is most superiority, However, the demand of raw material’s TiO2is high. The grade of Yunnan titanium slag produced by electric furnace smelting is about75%, which can not be used directly for production of titanium dioxide by chlorination process. Therefore, we should further purify titanium slag, the efficient use of titanium resources in Yunnan province has very important practical significance.In this work, the titanium slag from wuding yunnan province was taken as research project, made analysis the chemical properties, phase composition of titanium slag, roasting and acid leaching mechanism by X-ray diffraction, electron microscopy, scanning electron microscopy and other modern microscopic test. Determined the sodium roasting and acid leaching process for the removal of impurity, so as to improve the grade of TiO2, access to high quality titanium slag(ultra grade slag).Ultra grade slag is high quality titanium slag after the purification, with less impurity content and more TiO2content, which is the high quality raw material for chloride process.The main research contents and results were as follows:(1) The chemical properties and phase composition of titanium slag were studied by XRD and SEM, TiO2content was75.88%, the main impurities were CaO, MgO, Al2O3, FeO and SiO2, CaO+MgO content was1.73%. The main mineral phase were anosovite solid solution and silicate minerals with mosaic structure, Fe, Mg, Al dissolved in anosovite solid solution and Si, Ca distributed in silicate minerals.(2) The study of sodium roasting mechanism showed that adding Na2CO3could make impurity minerals in the anosovite solid solution and Na2CO3react to generate a series of compounds in high temperature, which could be soluble in acid or water, so as to promote the grade of TiO2.(3) Sodium roasting study showed that, Na2CO3and titanium slag were mixed as mass ratio of2:3and ground to-270～+325mesh, roasted at975℃for1.5h, the roasted product was leached by two periods sulphuric acid, the ultra grade slag with93.09%TiO2content and97%recovery and0.157%CaO+MgO content was obtained.(4) How the factors influenced the purification of titanium slag in sodium roasting process was learned by single factor experiment and analysised the purification of Al and Si, determined the best process conditions.(5) Acid leaching mechanism was studied and the best acid leaching condition was determined by orthogonal experiment. How the factors influenced the purification of titanium slag in acid leaching process was learned by single factor experiment and analysised the purification of impurities.(6) When mechanical activating, different activation methods and time for the titanium slag were studied, The studies showed that wet milling for30minutes was the best way of activation. Titanium slag and Na2CO3were mechanical activated for30minutes could reinforce the effect of removing impurities, made the reaction energy lower, and increased the reaction rate and the leaching rate, after mechanical activation-sodium roasting-acid leaching process, the ultra grade slag with94.42%TiO2content and98.19%recovery and0.125%CaO+MgO content was obtained.(7) Comparative experiments showed that the effect of Na2CO3and NaOH mixed adding was better than single adding Na2CO3and NaOH, However, the addition of NaOH was not the more the better, the mass ration of NaOH and Na2CO3was1:19could gain the ultra grade slag in which the TiO2content and recovery was the highest,95.13%and97.83%respectively, CaO+MgO content was0.135%.In this paper, based on the theories of mechanical activation-sodium roasting-acid leaching, a new technology of producing ultra grade slag has been put forward. This technology could remove impurities from titanium slag effectively, improved the grade of TiO2, opened up a new technology for the raw material of chloride process, made a reference for the industrial production of rich-titanium material made by titanium slag.