| 摘要 |
<p>A method of converting scrap metal to a powder suitable for making sinterable shapes is disclosed. Scrap metal equivalent to machine turnings, is subjected to a two-cycle process which graduates the conversion of turnings to powder. The scrap metal, in the first cycle, is cooled to a temperature below the ductile-brittle transition point for said metal and fragmented by impact to a particle size of -1/4 inch. In the second cycle, the fragmented pieces are again cooled to below the ductile-brittle transition point for said metal and fragmented by impact to a particle size of -1/4 inch. In the second cycle, the fragmented pieces are again cooled to below the ductile-brittle transition temperature and comminuted to a fine powder of -30 mesh. During each cycle, a cryogenic cooling medium is injected into the metal collection both at the entrance to fragmenting or comminuting apparatus as well as into a circulating mass of the metal within the apparatus. Screens are employed to classify the output of each apparatus and each have screen openings shaped to maximize through-put.</p> |
