PUR powder: Source and recycling processes
The PUR powder portion of about 1,900 tonnes is recovered from insulating materials during the process of demanufacturing refrigerators and freezers.
Most refrigerators and freezers that currently need to be disposed of contain CFC-based refrigerants (in the cooling circuit) and propellants (in the insulating foam).
However, the danger associated with hydrocarbons halogenated with chlorine and bromine (CFCs are halons), first identified in the 1980s, is that they have a major destructive effect on the ozone layer, which absorbs dangerous UV radiation from sunlight in the stratosphere, and also contribute to the greenhouse effect. As a result, their use in new appliances has been banned in Austria since 1995 under the CFC/Halon Prohibition Order.
The second step in processing refrigerators and freezers is therefore to recover the CFCs or hydrocarbons (HCs) from the insulating foam. In insulating foam (polyurethane foam
, PUR foam), CFCs or HCs are contained in the pores of the foam.
The PUR foam is separated from the housing under vacuum conditions, then ground into a powder (pore degassing), which releases the CFCs and HCs from the pore structure of the foam. The next step is matrix degassing. In matrix degassing, the CFCs or HCs bound in the foam matrix are released by gradual warming and stirring of the powder.
The CFCs and HCs released during pore and matrix degassing are extracted with the process air, separated, and “cracked” in a high-temperature furnace, i.e. broken down into hydrofluoric and hydrochloric acids, thereby rendering them harmless.
In the system operated by UFH GmbH, this separation takes place by means of a cryocondensation process (see UFH RE-cycling GmbH). In a cryocondensation process, a gas is purified by allowing it to flow into a heat exchanger, where it is brought into indirect contact with a cryogenic coolant (e.g. liquid nitrogen).
This freezes or condenses the impurities out of the gas, thereby purifying it. In the system operated by Energie AG Oberösterreich , this separation takes place by means of an activated carbon filter (see www.seg-online.de). The end product is a PUR powder that is free of CFCs and HCs, which can be used e.g. as an oil and chemical binder (see ÖKO-PUR).
The second step in processing refrigerators and freezers is currently handled mostly by recycling facilities operated by UFH RE-cycling GmbH in Kematen, and by Energie AG Oberösterreich in Timelkam with equipment based on the SEGsystem.