Processes for the Recycling of Sheet and Other Wrought Alloys from Aluminum Intensive Vehicles 970017

This paper will describe the main features of two newly-developed enabling technologies for the future establishment of an integrated system to recover the full value of the aluminum from scrapped aluminum intensive vehicles. These technologies are fluidized bed decoating and alloy sorting using analysis by laser induced optical emission spectroscopy.

Aluminum Intensive Vehicles will employ substantial quantities of sheet material, most of which will have fairly heavy paint coatings and possibly adhesives. While it may be possible to remove and segregate some of the closure panels and the major aluminum castings, the main body structure will need to be shredded to facilitate both the separation of the various aluminum and other materials and also the subsequent thermal decoating of paint films and adhesives. The decoating is necessary to ensure complete pyrolysis of the coatings and to avoid the excessive dross losses encountered when as-painted scrap is remelted. Alloy sorting of the shredded and decoated scrap is then the key next step; this will enhance the value of each alloy separated stream and minimize or eliminate the amount of metal that can only be directed to general foundry applications.

The system that is now feasible with the technologies Alcan has developed would take shredder scrap, which has been presorted by the usual mechanical and magnetic means, and process this through the fluidized bed decoater. This will remove the organics from the paints and adhesives and most of the residual paint pigments. The decoated scrap can then be readily sorted by the laser induced optical emission spectroscopy technique prior to remelting.

The principle features and characteristics of each of these technologies will be described with particular reference to their application to an industrial scale recycling facility.