How is Sorting Equipment Used in Recycling?
Sorting equipment for recycling is a collective term that includes everything from simple bins to complex, computer-controlled micro-processors.
The act of sorting is the most labor intensive, and the most critical step for the recovery of usable materials from the general waste stream. Mixed waste is too impure for any kind of immediate reclamation. It must be separated into the various types of paper, metals, and plastics. This separation is generally called sorting.
Some large material recycling facilities accept and process enough potentially recyclable material to justify expensive, complex sorting machines, in addition to human sorters. However, smaller operations have to rely more heavily on simply technology and humans. For these facilities, pre-sorting is a big help.
The most basic sorting equipment is home tubs which divide the recyclable items. If curbside recycling is available to homeowners, these bins will probably be emptied into larger, separated compartments on a recycling truck. Some places, consumers can take recyclables to a transfer station, where they are expected to do the bulk of the sorting. Roll-off containers will be labeled with the products they are to be filled with. Loading the containers directly on trucks eliminates further handling of the waste before it reaches the recovery facility.
For example, it is a simple mechanical process to separate ferrous metal from non-ferrous metal, glass and plastic. If these items are separated from paper, and the various grades of cardboard and paper are correctly sorted by the consumer, a great deal of expense is saved.
A sorting line for metal, glass and plastic will feed this stream onto a conveyor belt. A magnet will remove ferrous metal. An air sorter can suspend the other items, letting heavy glass fall to the lowest level. Aluminum will be somewhat suspended, and pulled out of the middle of the stream, while plastic can be blown off the top. Another mechanical means of removing the glass is for the mixed stream to be crushed and then run across a screen where the small particles of glass fall out.
Separating plastic types involves either manual sorting, or sophisticated electronics, Electronic methods of separating plastics analyze each piece traveling along a conveyor with infrared light or an optical scanner. Each piece is then deflected into the correct bin by bursts of air.
New technologies of sorting equipment which allow for better sorting with less human intervention will improve the economic value of recycling programs.