NO930175L - CLEANING AND / OR SURFACE TREATMENT OF METALS - Google Patents

Abstract

The invention relates to a process for decontamination of metal scrap, especially of aluminum or aluminum alloy, contaminated with organic material. The process includes heating the scrap in a fluidized bed of solid particles with heated fluidizing gas to a decontamination temperature high enough to consume the organic matter but below the melting point of the metal. The heating takes place in the presence of a protective material which protects the aluminum or aluminum alloy from significant oxidation while the scrap is kept in the bed at the decontamination temperature. Preferred protective materials include organic and inorganic fluorine-containing compounds, especially A1F3. The process is particularly effective in treating aluminum alloys containing magnesium, which are particularly susceptible to oxidation. Decontaminated scrap treated as above may be subjected to conventional metal recycling processes, such as metal cutting, to yield high-yield recycled metal. The process can also be used to protect metal, especially aluminum and its alloys, from excessive oxidation during heat treatments other than decontamination. The invention also relates to the treatment of briquettes of compact scrap without the need for protection against oxidation and without the need for prior tear or grinding.