Abstract: The sorting system provides a high degree of sorting accuracy even in high throughput sorting applications such as high speed wood chip sorting. In one embodiment, a sorting apparatus (10) includes a shaker (12) for distributing stock material, a spectrographic analyzer (14) for identifying unacceptable material in a product stream, an ejector (16) for diverting unacceptable material from the product stream, a three-zone sorting receptacle (18) and a recirculating system (20) for returning a selected portion of the sorter output for an additional pass by the analyzer (14) and ejector (16). The three-zone sorting receptacle (18) divides the product stream into an accept portion, a rejection portion, and an ambiguous portion including both acceptable product and unacceptable material. The ambiguous portion is re-sorted for improved accuracy at high throughput levels.

Abstract: A sorting apparatus according to the present invention includes a conveyor belt having a solid translucent sheet segment for carrying a stream randomly-arranged articles, ones of which are translucent and others of which are opaque. Preferably, the translucent articles are pieces of post-consumer plastic products (e.g., beverage containers) and the opaque articles are foreign matter, such as aluminum or polypropylene container tops or caps of the beverage containers. The conveyor belt carries multiple articles simultaneously through an inspection zone. A background light source is positioned in the inspection zone opposite the translucent sheet segment from the articles to direct light through the translucent sheet segment toward the articles. A video camera is positioned to receive light from the background light source transmitted through the translucent sheet segment and translucent ones of the articles.