Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Patent
1997-05-12
1998-10-06
Andrews, Melvyn
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
75687, 134 251, 134 30, 134 40, C22B 2100
Patent
active
058171630
ABSTRACT:
Aluminum scrap containing a carbon-containing coating is cleaned with about 212.degree. F. hot water, and then decarbonized with about 1000.degree. F. superheated steam which produces a carbon-containing volatile from the carbon-containing coating and a decarbonized aluminum scrap. A spent steam and carbon-containing volatile gaseous mixture at about 212.degree. F. is contacted with a warm water filtrate at a nominal temperature of about 132.degree. F., recovered from the process which causes the spent steam to condensed. The condensate at about 212.degree. F. is separated from the carbon-containing volatile and the latter combusted. The combustion products can be used to preheat indirectly other stream in the process or to dry the decarbonized aluminum scrap at a temperature low enough not to cause oxidation of the aluminum scrap. The decarbonized aluminum scrap and carbon-containing volatile are produced in an essentially combustion-product-gas free environment under a slight negative gauge pressure thereby preventing fugitive emissions. Because the decarbonized aluminum scrap is cleaner and less oxidized than that produced by conventional rotary kiln process, when the aluminum scrap is melted less dross is produced thereby producing a higher aluminum yield. Dross loss is estimated to be reduced from about 9% to about 5% which would result in about $500,000 saving per month for a plant processing 12.5 million lbs. of aluminum scrap per month.
REFERENCES:
patent: 5405428 (1995-04-01), Dube et al.
patent: 5597401 (1997-01-01), Megy
Andrews Melvyn
Logan F. Eugene
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