Grading method for olefin polymerization catalyst suspension liquid

Abstract

The invention relates to the field of olefin polymerization catalysts and discloses a grading method for an olefin polymerization catalyst suspension liquid. Grading is conducted in a cyclone; the cyclone comprises a cyclone body and a collecting chamber; the cyclone body comprises a cylindrical pipe section and a conical pipe section from top to bottom; a first overflow pipe in airtight connection with the collecting chamber is arranged inside the cylindrical pipe section; and the cyclone body communicates with the collecting chamber through the first overflow pipe only. The method comprises steps as follows: the olefin polymerization catalyst suspension liquid is introduced into the cyclone body via a feeding port and rotates in the cyclone body; large particles are discharged via an outlet in the lower part of the conical pipe section; and small particles enter the collecting chamber through the first overflow pipe and are discharged via an outlet in the collecting chamber. The olefin polymerization catalyst suspension liquid is graded with the cyclone, the product particle sizes at the upper outlet and the lower outlet of the cyclone can be effectively controlled, and requirements of different olefin production technologies for the particle sizes of olefin polymerization catalyst particles can be met.

Description

technical field [0001] The invention relates to the field of olefin polymerization catalysts, in particular to a method for classifying suspensions of olefin polymerization catalysts. Background technique [0002] Olefin polymerization catalyst components used to prepare polyolefins are generally known, generally using magnesium chloride as a carrier or dispersion medium, and supporting titanium tetrachloride and internal electron donors on it. This catalyst component generally has Solid particles of a certain shape are mainly spherical and spherical. [0003] In the polyolefin production process, there are requirements on the particle size distribution of the polymer. Especially when producing some specific grades, there are strict requirements on the particle size of the polymer, and its particle size distribution must be within the specified range to meet the needs of the device and the product. For example, when producing ultra-high molecular weight polyethylene produc...

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Problems solved by technology

[0005] At present, the particle size control of most polyolefin catalyst components adopts the chemical preparation method, which has the advantages of low cost and no additional process, but the control of the preparation process by this method is greatly affected by the environment, and the obtained product particle size The distribution is wide, and this method is not suitable for the preparation of polyolefin catalyst components that require precise particle size control

[0006] Olefin polymerization catalyst components are generally fine particles in the range of 0.1-100 microns. Commonly used screening methods are mainly used to remove large particles and residues. Due to the small particle size of catalyst components, screening methods are not suitable for use. Precise control of particle size of catalyst components

The methods generally used for particle classification, such as air cyclone separation, mainly use air or water vapor as the medium, which is obviously not suitable for the classification of olefin polymerization catalyst components, which need to be isolated from air, oxygen and water.

[0007] Looking at the above-mentioned prior art, the relevant particle classification technology is mainly used for the classification of larger particle size particles, and there is still no suitable classification method for olefin polymerization catalyst components, which have small particle size and strict media requirements

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