Feasibility research on sorting of black and dark dyed waste plastics using impact acoustic emission

In the doctoral thesis, an alternative method by using impact Acoustic Emission (AE) for scraped ASR plastic recycling is introduced, developed and researched. Impact AE sorting technology has been developed since last decade. Nowadays it was applied in food industries such like sorting of nuts, wheat corns and even candies. In such applications it has shown good performance and high efficiency. Compared with nuts and candies, the plastic scraps in ASR have the similar conditions which are probably used as specific characteristics by acoustic sorting technology. Tested scraped plastic samples are obtained from products of an ELV recycling company. During the sampling process, most of the scrap shapes were found to be homogenous: they are flexure or non-flexure flakes. Some other shapes like cylindrical structure are rare, and if it is necessary, other shapes could also be equivalent to equivalent flake shapes. On this basis, the elastic mechanical model of impact flake body and its frequency response model were established. Then the algorithm of AE signal acquirement and parameter measurement as well as data analysis were developed and programmed, after that the facilities, electronic devices and software system for experiment operation were installed. From the ELV recycling company, there were three kinds of black plastics PP, ABS and SMA were sampled, prepared and then applied in experiments by carrying out approximately 2200 impact processes. Data from the experiment were analyzed by using Rosin-Rammler- Sperling-Bennet (RRSB) distribution and fitting/regression analysis. The experimental data distributed in accordance with the mathematical model of the impact AE frequency response. By analyzing the fitting/regression results this method could be further developed and optimized in the future.