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What is PP granulation? Powder granulation method?

2022-05-12 Page view : 22 views

Granulation is to break the waste plastic products and then heat and melt them into particles, size and mung beans about the same, so that you can use these plastic particles to make new plastic products, this is called granulation. What is PP granulation? Powder granulation method?

PP is the English code of polypropylene, PP granulation refers to waste polypropylene plastic products (mainly waste plastic woven bags) after recycling, cleaning, plastic extruder re-plasticized polypropylene plastic particles, can be mixed into polypropylene new materials for use or directly used alone.

At present, the powder treatment technology is divided into wet granulation, boiling granulation, pressure molding, spray and disperse mists, hot melting molding and so on.

1. Wet granulation method
Wet granulation is to infiltrate some liquid or binder into solid fine powder and stir it appropriately, so that the liquid and solid fine powder are in close contact with each other, producing cohesive force and forming aggregates.

2. Boiling granulation method
Boiling granulation method is to make use of the wind from the bottom of the equipment to float the powder particles and the upper spray gun out of the slurry after full contact with each other and combined into particles.

3. Pressure molding method
The pressure forming method is to limit the granulated powder material in a specific space, and compress it into a dense state by applying external force. According to the physical system of the external force applied, the pressure molding method can be divided into two categories, that is, the molding method and the extrusion method.

4. Spray and disperse fog method
Spray and dispersion mists are used to make liquid or semi-liquid materials in a highly dispersed state become solid particles directly in specific equipment.

5. Hot melt forming method
Hot melting molding method is to use the low melting point characteristics of the product (generally less than 300℃), the molten material, through special condensation, so that its condensation crystallization into the required shape of sheet, strip, block, hemispherical and so on.

Powder granulation is a process affected by many factors; the selection of appropriate powder granulation technology needs to consider many factors:

1. Characteristics of raw materials

2. Processing capacity requirements
The unit time capacity of different granulation methods varies greatly, so the equipment investment and processing cost must be considered.

3. Product particle size distribution
The particle size of products obtained by different granulation methods varies greatly, such as the small particle size of spray granulation, while the particle size of compressed granulation products can be large, so the granulation method should be selected according to the required granulation method.

4. Product particle shape
The products obtained by mixing granulation and fluidization granulation are spherical particles with irregular shape. Rolling into a ball can obtain a smooth sphere; For regular particles with special shape, it is necessary to use compression and extrusion granulation. The selection of product particle formation should consider the requirements and convenience of subsequent processes.

5. Product particle strength
The dry process will inevitably lead to dust generation and is therefore not suitable for granulation of toxic or other dangerous powders. The wet process, on the other hand, requires drying after granulation and wastes some of the solvent. Some drugs do not come into contact with water, or recrystallize to form other structures during drying, which is not suitable for wet processes.

6. Dry/wet options

7. Porosity and density of product particles
Particle porosity and density in these two indicators also directly affect the strength of the product, such as used in the production of catalyst carrier particles, porosity and strength at the same time improve is a pair of contradictions. The size of porosity and density can be adjusted by process operating parameters.

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