A method for realizing regularization of particle size of titanium dioxide

Abstract

The invention relates to a method for realizing particle size regularization of titanium dioxide. The method comprises the following steps: analyzing the particle size of primary metatitanic acid aggregate particles in metatitanic acid slurry, and regulating and controlling the heating rate in the metatitanic acid calcining process according to the particle size of the primary metatitanic acid aggregate particles, thereby realizing particle size regularization of titanium dioxide. Compared with the prior art, the heating rates of titanium dioxide in different stages of calcination are regulated and controlled according to the size of the primary metatitanic acid aggregate so that the staying time of the particles in different temperature sections is changed, the purpose of adjusting the crystal transformation rate and the crystal growth rate of TiO2 is achieved, regularization of the particle size of titanium dioxide is achieved, and the method has guiding significance for actual industrial production.

Description

technical field [0001] The invention belongs to the technical field of titanium dioxide production, and in particular relates to a method for realizing regularization of the particle size of titanium dioxide. Background technique [0002] Titanium dioxide is commonly known as titanium dioxide. As a polymorphic compound, the excellent optical properties of titanium dioxide come from its specific crystal structure, and the specific crystal forms include brookite, anatase and rutile. The brookite crystal form belongs to the orthorhombic crystal system and is very unstable. When the temperature is higher than 650°C, it will transform into the rutile crystal form. It usually only exists in natural ores and has little industrial value. The anatase crystal form is relatively stable when the temperature is lower than 165°C, but when the temperature exceeds 730°C, the anatase crystal form begins to rapidly transform into the rutile crystal form. Anatase titanium dioxide has a good p...

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Problems solved by technology

During the invention and creation process of the present application, the inventor of the present application found the following problems in the patent: 1. The heating rate of the first stage was 1.67-2.22K / min, and the heating rate of the second stage was 1.25-1.66K / min , the heating rate of the third stage is 0.67-0.83K / min, the heating rate of this patent has been relatively slow, and the calcination time is relatively long. During the process, the inventors of the present application found that after metatitanic acid removes free water, its removal of hydrogen-bonded water and multi-layer adsorbed water is carried out simultaneously with desulfurization

3. The temperature in the third stage of this patent is controlled at 850-950°C. The calcination temperature does not take into account the difference between the crystal transformation rate of the crystal and the correlation between the crystal growth rate and temperature, and cannot simultaneously control the crystal particle size and temperature. The purpose of obtaining high rutile conversion rate

During the invention and creation process of the present application, the inventor of the present application found the following problems in the patent: the heating rate of the process from 780°C to 910°C in the patent was fast, greater than 8K / min, and the calcination temperature also did not take into account The crystal transformation rate of the crystal is different from the correlation between the crystal growth rate and temperature, and there is a rapid growth of the crystal, while TiO 2 Insufficient time for conversion from anatase to rutile

The inventors of the present application found the following problems in this patent: the heating process of this patent directly from 600°C to 960°C was too slow, resulting in prolonged residence time, accelerated grain growth and increased differences in particle size distribution

At present, the intermittent operation mode adopted in the hydrolysis process in the production of sulfuric acid titanium dioxide is difficult to meet the precise and stable production process control, and there are large fluctuations in the particle shape, size and distribution of different batches of hydrolyzed metatitanic acid

At the same time, the difference in heat and mass transfer rate caused by the difference in residence time at each temperature during the calcination process will affect the crystal form and particle size of titanium dioxide.

[0020] Therefore, the particle size and distribution of different batches of titanium dioxide have large fluctuations, which affect the pigment performance of the product

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