method for comminuting and cleaning waste plastic , in particular , mixed plastic with the following steps : a compacted material , especially , an agglomerate is produced from film scraps or film remnants comminuted into flakes and / or thick - walled plastic parts chopped up into chips , the compacted material is introduced into a disc or drum refiner and is ground therein in the presence of water , wherein the portion of compacted material of the goods located in the refiner amounts to at least 10 percent by weight , a fine grain fraction is removed from the ground stock exiting from the refiner , the remaining ground stock is washed and either mechanically dewatered and dried , or pulverized again in a further refiner stage in the presence of water , and subsequently dewatered and dried .