China Nonferrous Metallurgy

In view of the current situation of wide particle size distribution and lack of high-end production capacity of titanium dioxide by sulfuric acid method in China， in this study， low-concentration industrial titanyl sulfate solution was used as raw material， and authigenic seed hydrolysis process was used to systematically explore the internal regulation mechanism of bottom water volume， titanium liquid TiO2 concentration and curing time on the particle size distribution of metatitanic acid. The structure-activity relationship between the final particle size and structure morphology was analyzed by the characterization results， and the following main conclusions were obtained. The optimal hydrolysis process parameters were as follows： bottom water 16%， titanium solution concentration 205 g/L， and curing time 25 min. Under these conditions， the diameter-to-distance ratio of the prepared metatitanic acid product was as low as 1. 01， which belonged to a narrow particle size distribution and had excellent process stability. The metatitanic acid prepared by hydrolysis is a spherical polycrystalline aggregate formed by the accumulation of （30-60） nm grains through grain boundaries. Due to the adsorption of anions （SO4 2- ， OH- ） on the surface of the crystal nucleus at the initial stage of hydrolysis， the steric hindrance effect and electrostatic repulsion generated hinder the evolution of the crystal nucleus to single crystal， which promotes the formation of a mesoporous hydrated colloidal. The particle size control is based on the multi-stage competitive coupling of 'nucleation-growth-agglomeration'. The bottom water volume reduces the nucleation barrier by adjusting the initial supersaturation and establishes the nucleation advantage. The concentration of TiO2 increases the mass transfer resistance by adjusting the viscosity of the system， and inhibits grain coarsening and hard agglomeration. The ripening time effectively inhibits the particle size broadening caused by the Ostwald ripening effect by regulating the hydrolysis rate. The results can provide production parameters and process reference for industrial preparation of high-performance titanium dioxide.