METHOD OF RECYCLING SCRAP METAL

PCT No. PCT/US92/00807 Sec. 371 Date Jul. 28, 1993 Sec. 102(e) Date Jul. 28, 1993 PCT Filed Jan. 31, 1992 PCT Pub. No. WO92/13664 PCT Pub. Date Aug. 20, 1992.A method of embrittling cleaned steel particles is described, followed by a grinding and sorting operation. Depending on the initial carbon content of the steel scrap, a reducing and carbon-containing atmosphere may be provided to carburize the particles as they are being embrittled. A quenching operation is provided at the end of the process to embrittle the particles and before the particles are ground. The ground grit which is produced may then be sorted by size and used as an abrasive compound, or, alternatively may be further ground and annealed in a subsequent operation to provide suitable powder for forming sintered parts. Prior to annealing the grit may be further ground in a partial oxidizing atmosphere to preoxidize the powder, in order to provide oxygen directly within the powder to react with any residual carbon so that the carbon monoxide gas can be formed and the powder can be substantially free of both carbon and oxides when the reaction is complete. Alternatively, the powder may be preheated in a controlled atmosphere prior to annealing to preoxidize the powder.