Apparatus for removing volatiles from metal

Apparatus for removing volatiles from the surface of scrap aluminum, comprising:

• means for shredding scrap aluminum into pieces less than eight inches in length;
• a furnace adapted to be maintained at a relatively constant temperature and having a first zone for vaporizing volatiles on shredded aluminum and a second zone for pyrolyzing carbon on the aluminum;
• a conveyor for moving shredded aluminum through said furnace and having a perforated floor for supporting the aluminum as it is moved sequentially through said first zone and then through said second zone;
• a first burner adapted to receive gases containing volatiles from said first zone and burning them to produce hot gas;
• a second burner adapted to receive gases from said second zone and burning them;
• a fan adapted to receive said hot gas from said first burner and cooler gas from said second burner to provide a recirculating gas stream;
• means for distributing said recirculating gas stream to said first and second zones and causing such gas to flow upwardly through the holes in the conveyor floor to contact scrap aluminum thereon;
• means for controlling the temperature in the furnace by controlling said burner and the temperature of the hot gas produced by the burner;
• and
• means for controlling the oxygen content of the gases in the furnace;
• whereby the temperature in the furnace and the oxygen content of the gases can be controlled in relation to the speed and mass of the aluminum moved through the furnace to sufficiently vaporize the volatiles and pyrolyze the carbon on aluminum moved through the furnace while sufficiently minimizing oxidation of the aluminum.