Recovery of paraffin and/or microwaxes from scrap plastics, especially mixtures with a high polyolefin content

摘要

Clean, shredded scrap plastics are fed at 50-70 deg C on an inclined conveyer belt (2) to a feed hopper (3) and from this via a conveying screw (4) for increasing back pressure, a compensator (5) and a quick release coupling (6) into the pre cracking unit (7). The scrap plastic is reduced to a particle size of 5-50 mm, preferably 5-25 mm. The conveyer screw (4) has a water cooling system divided into three zones. Back pressure in the conveyer screw is 200-500 mbar. Scrap plastic is fed into the pre cracker 100-800 mm below the melt level. A compensator (5) between the screw (4) and pre cracker (7) compensates for the large temperature difference between the plastic and the pre cracker.