"The Bureau of Mines investigated carbonyl processing techniques for the recovery of the critical metals ni, CO, mn, and cr from domestic primary and secondary sources. In most cases, the source materials require reductive precarbonylation treatment to metallize the contained fe, ni, and CO compounds to render them reactive with carbon monoxide The critical metals were recovered either by direct conversion to the respective carbonyls or as upgraded products by carbonyl removal of an undesirable metal. Best metal-to-metal carbonyl conversion was under CO pressure, from 80 atm upward, and at 140 deg c. Carbonylation was accelerated by the addition of h2s in small quantities. Co pressure, temperature, promoter and pretreatment trends, and other factors enhancing metal carbonyl formation are presented." - NIOSHTIC-2 NIOSHTIC no. 10005717

National Institute for Occupational Safety and Health