Research On Preparation Of Titanium Dioxide By Red Mud Sulfuric Acid Method In Weiqiao Shandong

Red mud is a solid waste that produced during the production of alumina from bauxite.it contains a certain amount of iron oxide,So it is called red mud.With the gradual depletion of high-grade titanium ore resources,the production cost of titanium dioxide continues to increase,people are committed to finding new titanium ore resources,and red mud is a very good low grade titanium ore resources.Using Bayer’s Red Mud from Shandong Weiqiao as raw material,From its process mineralogical studies,it can be known that the the grade of TFe is 38.38%,the grade of Al2O3 is 16.61%,the grade of SiO2 is 7.44%,the grade of TiO2 is 6.09%.,and contains a small amount of CaO,MgO,P,S.The chemical multi-element analysis results of the raw ore show that the red mud is a high-iron and high-aluminum ore but low Ti content.First,the red mud ore was treated by the dilute sulfuric acid,got the best conditions:the concentration of sulfuric acid of 3 mol/L,the liquid-solid ratio of 12,the leaching temperature of 90℃,and the leaching time of 180 min.The leaching rates of iron and aluminum could reach 79.48%and 74.74%,and the leaching rate of titanium was only 10.68%.it indicats that Fe2O3 and Al2O3 are mostly dissolved and TiO2 remains in the leaching slag.The grade of TiO2 in the leaching slag is 16.46%,which belongs to titanium-rich red mud.Secondly,the titanium-rich red mud was treated by acid hydrolysis roasting and water leaching,got the best conditions:the acid hydrolysis roasting temperature of 250℃,the liquidsolid ratio of 3,the acid hydrolysis roasting time of 120 min,the water leaching temperature of 99℃,the water leaching liquid-solid ratio of 10,and the water leaching time of 60min.The leaching rates of iron,aluminum,titanium could reach 94.20%,93.33%,and 90.62%.It indicates that almost all of the titanium dioxide TiO2 was dissolved,and obtained the higher concentration of titanium solution.By analyzing the composition of the titanium solution,it can be concluded that the concentration of iron ions is 17.34 g·L-1 and the concentration of titanium ions is 4.74 g·L-1.The high concentration of iron ions will seriously affect the hydrolysis of titanium,so choose TBP extraction method,got the best conditions:the concentration of Cl-of 4 mol/L,the concentration of TBP of 60%,the O/A ratio of 1,and the time of 5min,the extraction rate of iron can reach 98.92%,and the extraction rate of titanium is only 8.86%.Finally,the titanium solution was treated by the hydrolysis,washing and calcination,it can got the best conditions:the hydrolysis temperature of 99℃,the iron-to-titanium ratio of 0.11,and the hydrolysis time of 120 min,the hydrolysis rate of titanium reaches 90.2%.The generated metatitanic acid precipitate was washed with 0.1%dilute sulfuric acid and distilled water for several times,and calcined in a muffle furnace at 900℃ for 60 min,then obtain rutile titanium dioxide that the grade of TiO2 is 95.4%.According to the analysis of the total process of preparing titanium dioxide from red mud in Shandong,Weiqiao,the recovery rate of titanium in dilute sulfuric acid primary leaching was 89.32%,the recovery rate of titanium-rich red mud after acid hydrolysis roasting and water leaching was 90.69%,the recovery rate of the titanium-containing leaching solution after the TBP extraction was 91.14%,and the recovery rate after the hydrolysis-washing and calcination was 90.22%.So,the total recovery rate of titanium was calculated to be 66.61%,and the grade of the final product titanium dioxide can reach 95.4%.Therefore,it is feasible to process the red mud to prepare titanium dioxide by this process,which can realize the comprehensive utilization of red mud,turn waste into treasure,and obtain high-grade titanium dioxide.Thermodynamic analysis of possible chemical reactions in red mud shows that under standard conditions(298.15K,1 atm),TiO2 didn’t react with sulfuric acid,but with the temperature increases,ΔfGmθ decreases and starts to be less than 0,which indicates that titanium dioxide and sulfuric acid occur reaction at high temperatures.According to the analysis of the model formula of the leaching kinetics parameters and the experimental results of the leaching rate at different temperatures,we can known that the kinetic reaction rate formula is 1-(1-μ)1/3=14e-21650/RT,the calculated activation energy is 21.65 kJ/mol,the pre-factor is 1.14s-1.