How to recycle polypropylene efficiently

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How to recycle polypropylene efficiently

in order to achieve the "horizontal self circulation" of household appliances (from household appliances to the reuse of household appliances), Mitsubishi Electric Co., Ltd. independently developed a mixed plastic selection and recycling technology

in the past, after smashing plastic parts in waste household appliances, most of them were "mixed plastic", which was very difficult to reuse. The technology developed by the company can automatically select and recycle high-purity polypropylene from "mixed plastics". Recycled polypropylene can also be used in the production of household appliances. In the future, the company will also develop technologies that can 100% recycle and reuse household appliance plastics

1. Background of development

based on the average value of four kinds of household electrical appliances in recycling factories across the country (Japan), the company's household electrical appliances recycling and commercialization ratio reached 73.3% in 2003. Among all kinds of resources, the recycling of metals and glass has made progress. The recycling of plastics has become a current topic

in 1999, the company established the first household appliance recycling factory Co., Ltd. in the same industry in shikawa City, Chiba county. Since then, the recycling of plastics has been started, and it is also the only company in the industry that has introduced micro crushing technology. "Kerstan also pointed out that the company has realized the degradation of" mixed plastics "for various miscellaneous commodities. However, the degradation and utilization of plastics are limited to mechanical and electrical products. At that time, materials with higher purity could not be obtained and applied to household appliances

the newly developed technology can automatically select polypropylene, which is widely used in "mixed plastics", and recycle it with high purity, and then reprocess it into a high-purity material that can be used in household appliances, automobile industry and aerospace industry, which has a strong demand for its peek products, so as to realize the reuse of polypropylene plastics

the company also plans to develop automatic selection technology for plastics such as polystyrene and ABS

2. Plastic recycling technology

in order to efficiently recover polypropylene from mixed plastics, the whole process consists of three parts: Micro crushing process, precise selection process and synthesis process. The micro crushing process is used as the pretreatment of the height selection process to crush the plastic into fragments with an average size of 8mm. In the precise selection process, polypropylene is recovered with high purity through dry thirst for knowledge and wet selection, as well as a unique device that can remove foreign matters. In the synthesis process, in order to ensure the quality of polypropylene after selection and recovery, modifiers are added to make granular raw materials

the process flow of high-efficiency polypropylene recovery is as follows:

raw materials → micro crushing process → high selection process → synthesis process → plastic particles

the detailed engineering process is as follows:

(1) micro crushing process: as a pretreatment of the precise selection process, remove the metal with a high magnetic selection machine. Break 10 ~ 80mm mixed plastic into 8mm pieces on average

(2) precise selection process: it is selected according to the principle that the wind makes light objects float upward; There are also dry specific gravity selection using different specific gravity to remove foreign matters, followed by wet selection using water, and the best combination of centrifugal force selection and floating selection to recover more than 99.8% of high-purity polypropylene. Then the company's unique device is used to remove foreign matters with a similar proportion to plastic, realizing the recovery of higher purity

(3) synthesis process: add modifier to the selected high-purity polypropylene, and form plastic particles after extrusion. Due to the addition of the best modifier, plastic particles with high purity can be used as materials for household appliances to realize reuse

3. Development plan

in the middle of 2005, a new factory will be established in Chiba kawashi Co., Ltd., which plans to recover 1000 tons of polypropylene from mixed plastics every year. It is planned to launch the automatic selection technology of polystyrene and ABS by 2008 to increase the recycling capacity of the factory to 4000 tons of plastic (including polypropylene) per year. (translated by Kong Xinbo)

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