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Application of Iron Remover in Plastic Recycling
Apr 25, 2018

Application of Iron Remover in Plastic Recycling

 

Plastics usually go through five stages of recycling process. The purity of the plastic after the stage of plastic separation plays a decisive role in the quality of regranulation in the thermoplastic stage. The importance of sorting can not be ignored. However, at present, most of the recycling enterprises in China are still lagging behind in the sorting technology, and they are mostly selected manually. However, with the expansion of production and the increase in labor costs, automated sorting systems will gradually replace manpower sorting.


  There are three major sorting needs in the recycled plastics market: removing metals from plastics, sorting plastics of different colors, and different types of plastics. As the leader in plastic recycling and sorting technology, S+S (Shuangshi Sorting Technology Co., Ltd.) has corresponding inspection technologies for these three applications:


I. Sorting metals


The S+S sorting system uses an electromagnetic induction metal detector. Its working principle is that the energized coil forms a magnetic field, and once the metal enters, the magnetic field changes. The electromagnetic induction type metal detector based on this principle can confirm whether there is metal passing through monitoring the change of the magnetic field. Compared with widely used iron remover, this technology is not only effective for ferromagnetic metal, but also can detect stainless steel, copper, etc. Non-magnetizable metal.


Currently, the color sorting machine in the market mainly uses two kinds of optical color separation sensors and high-efficiency digital analysis software to realize the color separation function. One is a CMOS sensor, and the other is a CCD sensor.


CMOS is widely used in grain color selection applications, and has since been introduced into the plastic color selection industry. However, each pixel in a CMOS sensor design needs to pass through an amplifier before it is converted into a digital signal. Therefore, the image quality of CMOS is slightly inferior, and the content of noise plastic is The application with little or great material color difference is more appropriate.


Compared with CMOS, true-color CCD sensors can ensure that pixel signals are not distorted during transmission, and therefore the imaging effect is even greater. True-color CCD sensors are close to the human eye and are ideally suited for applications requiring complex color mixing or extremely high purity requirements. All of the S+S recovery systems use CCD sensor systems, and can even produce pale blue and light green bottle tablets in PET bottle tablets.

Three sorting different plastic materials


In the recycling of plastics, manpower sorting also encounters some difficulties. Some polymers are difficult to identify with the same color, such as the same color of PET and PVC. Different plastics in the thermoplastic phase will have different thermal melting points (eg, PET is about 260° C., PVC is about 170° C.), and if the different polymers are not completely separated, the final product will have large defects. The S+S sorting system uses near-infrared detection technology. The plastic passes through the near-infrared detection head and the light is reflected by the plastic. The wavelengths of light reflected from different plastics are different. The high-performance computer can identify different plastics through different wavelengths ( As shown below, this technology is not limited by the proportion of materials and the appearance of color, and it is being applied more and more widely in the recycling industry.


In addition to the core detection sensors, an automated sorting system also needs to be equipped with a suitable material handling system to spread the material evenly, avoiding false rejects caused by overlapping of materials. The fast and accurate reject device can accurately locate the impurity position and eliminate it in time. Only when the three links are closely combined can the efficient sorting of the plastic recycling stage be achieved.


The S+S, which specializes in the production and R&D of recycling sorting systems, has developed many series of recycling and sorting systems based on the above technologies. In this year's PETPoint S+S according to the needs of the PET bottle recycling industry, the new Fale Purifier separation system can achieve a machine more versatile, Flake Purifier uses a modular design, can be in a sorting equipment The metal detector, CCD camera and near-infrared sensor module are assembled to realize the three functions of sub-metal, sub-colored plastic and heterogeneous plastic simultaneously. It can greatly improve the efficiency of plastic recycling and has great help for PET purification.