Study On Production Process Of Titanium Dioxide By Hydrolysis With TiCl₃ Leaching Solution

Titanium dioxide is an important white pigment,During the preparation of titanium dioxide,hydrolysis,rinsing and calcination have a significant effect on the performance of the product.In this study,the TiCl₃ leaching solution was used as the raw material,and the TiO₂ was prepared by hydrolysis under the condition of the autogenic seed and normal pressure.The influence of different hydrolysis conditions on the particle size,the rate of hydrolysis and the content of impurities in the products was studied.The results were as follows:(1)Condensation and premixed treatment can not only improved the hydrolysis rate of titanium significantly,but enhanced the sphericity of hydrolysates,resulting in hydrolysates have more regular particle morphology and uniform particle size distribution.(2)When the dilution ratio increased,the hydrolysis rate of titanium and the particle size of the products increased,but the increase of dilution ratio reduced the driving force of hydrolysis as well as the hydrolysis rate of raw materials;When the hydrolysis time prolonged,the hydrolysis rate of titanium and the particle size of the hydrolysate increased,but the content of impurities in the products increased.With the increase of hydrolysis temperature,the hydrolysis rate of titanium increased gradually,the grain size of the hydrolysate decreased first and then increased.The optimum hydrolysis condition were as follows:the dilution ratio is 1:1,the time of hydrolysis is 2.5 h,and the temperature of hydrolysis is 130 ?.Under these conditions,the hydrolysis rate of raw materials is 93.58%,the morphology of the hydrolysates is regular and the average size of the product is 680 nm.(3)The optimum washing condition were as follows:Using hydrochloric acid as an acidic medium,the concentration of H+is within 2.18?3.08 mol/L,the washing temperatur is within 45?50?,the recruitment of TiCl₃ is 6 mL(100 mL distilled water gauge),and the washing time is 30?35 minutes.Under this condition,the content of Fe and V in the hydrolysates can be reduced to less than 0.003%.Using ethanol as dispersant,the degree of agglomeration between particles can be reduced effectively with high speed stirring.(4)The influence of calcining time and calcining temperature on the whiteness,grain size and crystal conversion rate of the calcined products was investigated in this paper.The experiment showed that the grain size and crystal transformation rate of the product increased with the prolongation of the calcining time,and the brightness of product increased first and then decreased with the prolongation of calcining time.With the increase of calcining temperature,the grain size and crystal transformation rate of the product increased,the whiteness of the product increased first and then decreased.The optimum calcining condition were as follows:the calcining time is 1.5 h,and the calcining temperature is 750.Under these conditions,the average size of the calcined products is 445 nm,the whiteness is 83.8%,the R value is 95.8%,and the purity is 99.80%.