Research And Experimental Study Of Automatic Sorting System For Recycling Of Plastics In Waste Electric Household Appliances

In order to realize the goal of creating a sustainable society which is environment friendly, China has issued waste electrical and electronic product recycling regulation. This regulation has set the standards for recycling of discarded household electric appliances. A large portion of these discarded household appliances is composed of different kinds of plastics, so how to identify and sort the plastics efficiently is very important to the whole process of electric appliance recycling. Usually, after dismantling of appliances all different kinds of plastics are mixed together, which makes it very difficult to do further treatment. This kind of situation has affected a lot the efficiency of recycling of household appliances. So, the research of automatic sorting mechanism and technology for different plastics has great practical significance.Based on the analysis of existing research and technology of plastics sorting abroad, this paper did the research about plastic sorting in the recycling of discarded household appliances in China and the following results were obtained: Firstly, this paper summarized the advantages and disadvantages of existing technologies and analyzed their applicable ranges. Then this paper proposed an automatic plastic sorting solution based on the characteristics of household appliance recycling in China.Secondly, based on the theory of near infrared spectrum identification, this paper analyzed the requirement of acquisition and treatment of plastic spectrum and developed following mathematical processing procedure for the identification of different plastics: First step, filter obtained spectrum using methods of Neighboring Points Comparison, Least Squares Smoothing, Norris Differential and Centralization treatment. Second step, extract plastic composition information by applying Fuzzy Recognition Algorithm, and classify different plastics based on this information. Third step, calculate the Mahalanobis distance of main composition to determine the exact plastic type.At last, based on the theory and methods mentioned above, this paper established a near infrared spectrum database of typical plastics used in household appliances by testing standard plastic specimen and developed the <>. This paper also used this system to test samples of randomly acquired plastics from processing site of waste household appliances, and achieved the identification accuracy of 95%.