DEFOAMING METHOD FOR WET TYPE GRAVITY SEPARATOR FOR WASTE PLASTIC

摘要

PROBLEM TO BE SOLVED: To provide a defoaming method by which foaming of a gravity liquid can be suppressed and the effect for suppressing the foaming can be maintained when plastic wastes containing chlorine are separated from mixed plastic wastes, which has been separated from industrial wastes or municipal wastes, by a gravity liquid circulation type gravity separation system. SOLUTION: The defoaming method comprises at least one of a process for charging a adsorbing agent capable of adsorbing a foaming component in the gravity liquid into the gravity liquid and adsorbing and removing the foaming component or a process for charging an acidic substance such as hydrochloric acid into the gravity liquid and controlling the pH of the gravity liquid to be acidic of <=4.5 or a process for heating the gravity liquid to a temperature of >=60 deg.C to remove the foaming component in the gravity liquid.