Abstract: A method for cleaning thermoplastic material especially for reclaiming thermoplastic material from scrap material which includes in addition to the thermoplastic material, materials having a higher melting point than the thermoplastic, such as metal, thermosetting material, etc. The scrap material which has been treated to remove large particles of metal and/or other hard materials is heated and extruded to thereby provide a confined pressurized stream of melted thermoplastic material containing therein small metallic or other unmelted particles. A portion of the stream of melted material is filtered to provide a filtrate composed of melted thermoplastic material containing therein unmelted materials having a size less than a preselected size.

Abstract: In a system for comminuting materials containing thermoplastics, the temperature in the comminuting chamber is monitored and a spray of cooling liquid is charged into the cutting chamber when the cutting chamber is at a temperature greater than the boiling temperature of the cooling liquid and less than the melting temperature for the thermoplastic being comminuted. By using heat of vaporization to extract heat from the cutting chamber, the likelihood of the plastic softening and/or melting and clogging the comminuting screen is substantially reduced. A higher throughput of materials is obtained because of material remaining harder. By vaporizing the liquid, the discharged comminuted material may be maintained very dry for later classifying. Preferably, the cooling liquid is discharged intermittently to keep the temperature of the comminuting chamber within predetermined upper and lower temperature limits.