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Use of Cryogens to Reclaim Nonferrous Scrap Metals.

Valdez EG; Dean KC; Wilson WJ
NTIS: PB 214 786 :13 pages
Three cryogenic systems that utilized liquid nitrogen, dry ice, and methanol with dry ice were investigated in conjunction with crushing and classifying techniques to separate and reclaim the metallic components contained in insulated wires, shredded automobile nonferrous metal concentrates, small motors, generators, and rubber tires. Wire strands, 2 to 6 inches long and insulated with polyvinyl chloride and neoprene, were chilled at -60 deg and -195 deg c, then roll-crushed and processed by water elutriation; this procedure resulted in two products--a sink fraction that was 99 percent metallic and a float fraction that was 99 percent nonmetallic. Excellent separation of zinc die-casting alloys from copper and aluminum contained in shredded automobile nonferrrous metal concentrates was attained by chilling at -72 deg c for 1 minute, crushing in a grateless hammer mill, and screening. From the screened products, 97.2 and 100 percent of the copper and aluminum, respectively, were recovered in the plus 1-inch fraction, and 100 percent of the zinc was recovered in the minus 1-inch fraction of over 97 percent zinc die-cast purity. Laboratory experimental results indicated that a sufficiently low temperature could be attained by indirect chilling to permit use of a liquid co2- dry ice system on insulated wires and mixed nonferrous metallic concentrates.
Publication Date
Document Type
IH; Report of Investigation;
Fiscal Year
NTIS Accession No.
NTIS Price
Identifying No.
RI 7716
NIOSH Division
Source Name
NTIS: PB 214 786
Page last reviewed: December 10, 2021
Content source: National Institute for Occupational Safety and Health Education and Information Division