Specialized metallurgical processes – compositions for use therei – Processes – Free metal or alloy reductant contains magnesium
Patent
1994-04-12
1995-04-11
Rosenberg, Peter D.
Specialized metallurgical processes, compositions for use therei
Processes
Free metal or alloy reductant contains magnesium
C22B 1104
Patent
active
054054303
ABSTRACT:
A process is disclosed for the recovery and assay of gold, silver (PMs) and the 6 platinum group elements (PGEs) from playa-evaporite sediments. Fine sediments are subjected to a primary leach with a highly caustic sodium thiosulfate leach liquor to produce a metal-pregnant solution. After filtration the pregnant solution is subjected to a two-stage precipitation of gold, silver and PGE values. In a first stage precious metals and some PGE elements are precipitated by lead acetate or sodium borohydride reagents. The precipitate may be subjected further to desulfurization and metallic footing to produce a lead-precious metal sponge. The sponge is de-leaded by firing and cupelling, selective cementation or electrolysis and reduction to dore is best effected by a carburizing distillation. The final recovery of the metal values is produced by controlled acid parting into individual precious metals and cupellation to the metallic state. In a second stage, the first stage precipitation liquor is scavenged by metal-exchange at reduced pH for additional metal values and cupellation to the metallic state. The second stage scavenger precipitate is an impure metallic powder and values are recovered by standard reduction and separation methods. Assay of the product (heads and precipitates) may be effected by high temperature methods developed for these types of deposits. Recovered flower sulfur and sulfite liquors are used to regenerate recycled thiosulfate. Mud leach tails are treated for agricultural use and land reclamation.
REFERENCES:
patent: 4070182 (1978-01-01), Genik-Sas-Berezowsky
patent: 4269662 (1981-05-01), Kerley, Jr.
patent: 4369061 (1983-01-01), Kerley, Jr.
patent: 4654078 (1987-03-01), Perez
Maslentitskii et al., Dissolution of Noble Metals at Elevated Temperatures and Pressures in the Presence of Various Complexing Agents, (translation) of pp. 221-227 of Chapter VII of Autoclave Processes In Non-Ferrous Metallurgy, (Moscow, 1969).
Berezowsky et al., Recovery of Gold and Silver from Oxidation Leach Residues by Ammoniacal Thiosulphate Leaching, Paper Presented 108th Annual Meeting of AIME, New Orleans, Feb, 18-22, 1979.
Zipperian Jr. et al., Thiosulfate Technology for Precious Metal Recovery, Summary of Paper Presented at 115 Annual Meeting of AIME, New Orleans, Mar. 1986.
Zipperian et al., Gold and Silver Extraction by Ammoniacal Thiosulfate Leaching from a Rhyolite Ore, 19 Hydrometallurgy 361-375 (1988).
Hemmati et al., Study of the Thiosulfate Leaching of gold from carbonaceous ore and the quantitative determination of thiosulfate in the leached solution, Paper Presented, 1989 Extraction Metalurgy Symposium, London, Jul. 10-13, 1989.
Changlin et al., Leaching Gold by Low Concentration Thiosulfate Soltion, Randol, pp. 293-298, Vancouver 1992.
Gundiler et al., Thiosulfate Leaching of Gold From Copper-Bearing Ores, Paper Presented at SME Annual Meeting, Reno, Feb. 15-18, 1993.
Dhawale, Thiosulfate, 70 Journ. Chem. Ed. 12-14 (1993).
Rose, The Mettallurgy of Gold 2nd ed. 1896 Chapter II pp. 30-31.
Gray et al. The geochemistry of Gold In Lateritic Terrains Ch. V.3 in Butt et al. eds. vol. 4 HandBook of Exp. GeoChem (1992).
Langhans Jr. et al., Copper-catalyzed thiosulfate leaching of low-grade gold ores, 29 Hydrometallurgy 191-203 (1992).
Blackman Lawrence
Groves William D.
LandOfFree
Recovery of precious metals from evaporite sediments does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Recovery of precious metals from evaporite sediments, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Recovery of precious metals from evaporite sediments will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1535789