Recycling of waste plastics - crushing
Waste plastic is more formally called post-consumer plastic waste, which refers to the waste plastic products after consumption or use. Plastic in the synthesis, molding processing, circulation and other links will also produce waste, waste, these plastic waste is also called pre-consumption plastic waste, although this also belongs to the scope of waste plastics, but because of its relatively small amount of production, easy to recycle and recycling value, the general manufacturers will be their own recycling and recycled products directly used in production. Therefore, usually said waste plastic mainly refers to post-consumer plastic waste.
The crushing of waste plastic. Most waste plastics need to be crushed before being separated. When cleaning large products of bottle containers and mechanical cleaning, it is also necessary to crush waste plastics; In the dosing process, in order to ensure the dispersion of the additive, the waste plastic is also required to be crushed. Reduce its size to a certain allowable degree; In melt granulation, the feed of the extruder is suitable for granular materials, and the open mill is suitable for powdery or other shapes of small size materials.
The shape of waste plastics is complex and the size is different, especially some large waste products must be crushed into small pieces of a certain size by crushing, grinding or shearing means, before they can be recycled or further molded into a variety of recycled products. For some productive wastes, such as the waste edge, waste and waste produced by injection molding and extrusion processing plants, they can be directly recycled after being crushed. According to the different forces applied to the material, the main equipment for crushing waste plastics can be divided into four categories: compression, impact, grinding and shearing.
The selection of crushing equipment and blades mainly depends on the type, shape and degree of crushing required. Different materials of waste plastics should use different crushing equipment and grinding blades of different materials: hard PVC, PS, plexiglass phenolic resin, urea formaldehyde resin, polyester resin, etc., is a kind of brittle plastic, brittle and fragile, once subjected to compression force, impact force, easy to crack, broken into small pieces, For such plastics, compression or impact crushing equipment is suitable for crushing; For ductile plastics with high ductility at room temperature, such as PE, PP polyamide, ABS plastics, etc., it is only suitable to use shear crushing equipment, because they are subjected to external compression, bending, impact and other forces, generally will not crack, difficult to break, should not be used brittle plastic crushing equipment. In addition, for elastic, soft and low-temperature brittle materials, such as soft PVC, it is best to use low-temperature crushing equipment.
In addition, the crushing equipment should be determined according to the degree to which the waste needs to be crushed. If large pieces are broken into small pieces, compression, impact or shear crushing equipment should be used; If the small pieces are crushed into fine powder, fine particles, grinding grinding equipment is mainly used. Large products or require small size of fine particles, powder, generally first a coarser degree of crushing, and then according to the requirements of the medium or fine degree of crushing.
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