Method and machine for recycling discarded carpets

Abstract

A method and machine are disclosed for using a cold dry abrasion step for separating segments of discarded carpet into pile material (usually nylon) and backing layers (usually polypropylene) for recycling. A preferred method of abrasion uses dry ice pellets (made of frozen carbon dioxide) which are ejected at high speed from a set of nozzles that shoot the pellets directly into an abrasion zone, as a segment of discarded carpet on a conveyor system is being stripped apart and disassembled. The dry ice pellets 'freeze' the binder material (usually latex) by lowering it to a temperature that makes the binder brittle and easy to break apart. The pellets also serve as abrasive agents, in a manner comparable to sand-blasting; however, unlike sandblasting or liquid (steam or chemical) systems, the dry ice pellets evaporate (sublimate) directly into gas without going through a liquid phase, and without leaving any liquid or gritty residue. This eliminates the need for a drying operation, which saves time and energy and avoids a potential air pollution problem; it also renders the recyclable output material free of unwanted liquid residues, grit, or other materials that would decrease the value of the output material. This invention also discloses other processing methods which use cold dry abrasion, such as the use of freezing to render the latex binder brittle, coupled with the use of pellets made of a compatible material (such as nylon pellets, for carpets with nylone piles) as abrasive agents that can be mixed with the pile fibers that are recovered from a carpet without decreasing the value of the reclaimed pile material.