Receiving and Initial Sorting
Materials arrive by truck and are tipped onto a receiving floor. Workers perform an initial check for obviously problematic items (large plastic bags, garden hoses, hazardous materials) and remove them before materials enter the sorting line.
Large materials (cardboard, plastic film) are often pre-sorted at the tipping floor. The remaining material enters a conveyor belt system that feeds through increasingly sophisticated sorting equipment.
Screens and Trommels
Disc screens separate material by size. Flat paper and cardboard are directed one way; smaller, rounder containers bounce over the discs and fall into another stream. Trommels — large rotating cylindrical drums with holes — further classify by size.
This two-dimensional sorting (flat vs. 3D, large vs. small) is the foundation everything else builds on. Getting the sizes right early dramatically improves downstream sorting efficiency.
Optical Sorters
Near-infrared (NIR) spectroscopy identifies different plastic types at high speed. A sensor scans the material stream and identifies each piece; air jets then blast selected items into separate bins in milliseconds. Modern optical sorters can identify and separate eight or more different plastic types and paper grades.
RGB cameras sort by color — separating green, brown, and clear glass; identifying colored paper grades.
Eddy Current Separators and Magnets
Magnets extract ferrous metals (steel cans, steel packaging). Eddy current separators use a rapidly rotating magnetic field to repel non-ferrous metals — aluminum cans literally fly off the conveyor into their own bin. This elegant physical principle allows aluminum to be separated without contact.
Residual hand-sorting stations catch anything the automated systems miss and correct misrouted materials.
Baling and Shipping
Separated material streams are compressed into dense bales by hydraulic balers. A bale of aluminum might weigh 1,200 pounds; a cardboard bale might weigh 2,000 pounds. Bales are staged in the facility yard and shipped by truck or rail to end-market processors — paper mills, aluminum smelters, glass processors.