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Libroplantasingl

FUNCTION Optical separation allows segregating several types of plastic (PET, HDPE and mixed plastic) in package sorting plants, although current equipment allows the separation of other plastics, beverage cartons, ferrous and non-ferrous metals, P/C, glass, organic matter, etc. Recoverable materials from plastic, beverage cartons and P/C packages with standard sizes contained in the streams classified by the preceding processes can be selected by applying automated optical devices. DESCRIPTION This principle involves passing a uniform stream on a belt with a controlled speed of previously classified components, generally by ballistic separators (rolling current) or trommels (passing material of medium size) within the range of action of an optical scanner or sensor. The material to be selected is stabilised in a highspeed belt, and when it is stable on a specific point of the belt the composition of the material is detected by a scanner that also determines its position. If the belt speed is known, one can calculate the time taken to reach the end of the belt, where a block of electrovalves is installed that blow the material into the corresponding chute. The technology most commonly used to conduct optical separation of materials is near-infrared (NIR), but other technologies allow separating materials of different colours using optical spectrometry (colorimetry) and separating materials by X-ray densitometry. The most widely used devices are NIR optical sorting units, which comprise the following elements: • Frame: structure that supports the various elements of the equipment. • Software: programme used to identify the materials. Depending on the reading, the sensor will issue a command to control the corresponding air flow. Unit parameters such as belt speed, calibration and data storage are controlled. • Acceleration conveyor belt: meant to stabilise the material that is selected for detection by the scanner and subsequent Optical separators


Libroplantasingl
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