High-temperature cyanide leaching of platinum-group metals from automobile catalysts - a process development unit.
Kuczynski-RJ; Atkinson-GB; Walters-LA
Reno, NV: U.S. Department of the Interior, Bureau of Mines, RI 9428, 1992 Jan; :1-11
The U.S. Bureau of Mines operated a 2,000-g (4.4-lb) batch process development unit for recovering platinum-group metals (PGM) from automobile catalysts. Virgin monolith, used pellet, and used monolith catalyst samples were tested. Leaching twice with 1-pct sodium cyanide (NaCN) solution at 160 deg. C for 1 h dissolved more than 95 pct of the PGM from virgin catalysts and more than 90 pct from used pellet catalysts. More than 85 pct of the PGM was dissolved from used monolith catalysts when a third autoclave step was added. Solid PGM concentrates containing more than 99.8 pct of the dissolved PGM and analyzing greater than 70 pct PGM were recovered by heating the pregnant leach solutions from virgin catalysts to 250 deg. C and used catalyst to 275 deg. C for 1 h. The solution after heating contained less than 0.2 ppm total cyanide. The virgin residues passed the EPA extraction procedure toxicity test (EP Tox Test), the EPA toxicity characteristic leaching procedure (TCLP), and the California waste extraction test (WET) for all elements except Ba. Adding sodium sulfate (NA2SO4) to the virgin leach residues reduced the amount of Ba dissolved to an acceptable level. The used leach residues passed the EP Tox Test for all elements but failed the WET and TCLP for Pb.
Metals; Metallurgy; Metallic-fumes; Metal-industry; Metal-fumes
143-33-9; 7757-82-6; 7664-93-9; 10102-44-0; 124-38-9; 7439-92-1; 7440-44-0
Report of Investigations
NTIS Accession No.
Reno, NV: U.S. Department of the Interior, Bureau of Mines, RI 9428