Crushing of titanium dioxide

After the titanium dioxide large sizes are calcined aggregate and sinter, it must be pulverized to a size of the original pigment substantially (about 0.15 0.35μm ~), in order to fully reflect its optical properties and pigment properties. The basic pigment particles are primary primary particles produced during hydrolysis, and gradually grow into basic pigment particles during calcination, and then sintered together at a high temperature. The pulverization process only breaks up the aggregates of these basic pigment particles, and the original basic The pigment particles are mechanically pulverized and cannot be powdered again. The pulverization of titanium dioxide after calcination is generally referred to as dry milling or pre-pulverization (pulverization after surface treatment is referred to as post-crushing).

Titanium dioxide is a superior white pigment, so the requirements for the crushing equipment are firstly that the pollution of the product is small, and secondly, the fineness can be graded when crushing, and the output can be large and the energy consumption can be small. The pre-grinding equipment usually includes: ball mill , Raymond mill (ring roll mill, or suspension roller mill), universal crusher (centrifugal mill), hammer mill, steam mill (flow energy mill, jet mill), etc. Raymond mill is generally used for pre-grinding. Raymond mill is used in most factories in China, and a few small factories still use universal crushers.

The principle of the universal pulverizer is that under the centrifugal force generated by the high-speed rotating blade, the material is ground between the blade and the tooth plate of the casing, and there is a collision between the material and the blade, but the previous 2 The type of impact is dominant, and the fineness is adjusted mainly by adjusting the distance between the blade and the dental plate. The universal crusher has a small footprint and convenient operation, but the output is small, the energy consumption is high, and the pollution to the material is large. The surface of the pulverized particles is irregular, and the oil absorption of the product is high.

Raymond Mill is an ideal pre-grinding equipment recommended by the titanium dioxide industry at home and abroad. Compared with the universal pulverizer, it has low pollution, large output, low energy consumption (about 1/5 of the universal pulverizer), and can be graded by the grading equipment in the mill. The oil absorption is low, and the particle shape is smoother and smoother than the centrifugal grinding. However, the working principle of Raymond mill is to crush by the pressing action between the grinding roller and the grinding ring. Therefore, some fine particles are pressed and adhered together to become softer flake particles during the pulverization process, so For some products that require high dispersion, such as titanium dioxide for papermaking and chemical fiber, after crushing with Raymond mill, they are pulverized by hammer mill, impact mill or steam mill to break the aggregated particles adhering together. .

The working principle of the steam jet pulverizer is that the material is pulverized by the collision of the pigment particles themselves under the action of the high-speed air stream, and the pulverized material can reach the sub-micron level, the particles are smooth and the particle size distribution is narrow, and the mechanical pulverization is generally performed. It's hard to do this. Vapor stream typically used for comminution mill after the surface treatment (after crushing), rutile titanium dioxide and anatase titanium dioxide generally does not require treatment of the surface (i.e., a so-called dry grinding grade titanium dioxide), can be crushed Sold as a finished package.