From Cyanide Solution Patents (Class 75/729)
  • Process for the elution of precious metals absorbed on active carbon
    Patent number: 5769925
    Abstract: A powerful reducing agent such as hydrazine monohydrate is added to the standard eluent solutions such as NsOH-NaCN with or without alcohol. The kinetics of elution of gold or of silver are thus markedly enhanced.
    Type: Grant
    Filed: June 12, 1996
    Date of Patent: June 23, 1998
    Assignee: UM Enginerring S.A.
    Inventors: Sarah Harvey, Andre Van Lierde, Pierre Louis
  • Hydrometallurgical extraction and recovery of copper, gold, and silver via cyanidation and electrowinning
    Patent number: 5667557
    Abstract: A hydrometallurgical process for treating copper feed materials containing gold and/or silver by simultaneously leaching copper, gold and/or silver into an aqueous cyanide solution, recovering copper in metallic form by electrowinning and regenerating cyanide ions is provided, wherein high current efficiencies are achieved at high current densities and at low copper concentrations.
    Type: Grant
    Filed: September 26, 1995
    Date of Patent: September 16, 1997
    Assignee: E. I. Du Pont de Nemours and Company
    Inventors: Christopher Andrew Fleming, Walther G. Grot, John Anton Thorpe
  • Precious metal recovery process from carbonaceous ores
    Patent number: 5358699
    Abstract: A process for recovering at least one precious metal from an ore containing carbonaceous material is disclosed. The process involves the use of certain plant derived ortho-quinone containing components, in particular, certain lignin and/or tannin derived components containing ortho-quinone functionality.Preferred compositions comprise at least one ligno sulfonate component containing ortho-quinone functionality. In the process, the use of at least one additional oxidant capable of maintaining the ortho-quinone containing functionality in the desired oxidation state provides for integrated process synergy.
    Type: Grant
    Filed: November 24, 1992
    Date of Patent: October 25, 1994
    Assignee: Ensci, Inc.
    Inventor: Thomas J. Clough
  • Precious metal recovery process from sulfide ores
    Patent number: 5344625
    Abstract: A process for recovering at least one precious metal from an ore containing metal sulfide material is disclosed. The process involves the use of promoting amounts of certain plant derived ortho-quinone containing components, in particular, certain lignin and/or tannin derived components containing ortho-quinone functionality. Preferred compositions comprise at least one ligno sulfonate component containing ortho-quinone functionality. In the process, the use of at least one additional oxidant capable of maintaining the ortho-quinone containing functionality in the desired oxidation state provides for integrated process synergy.
    Type: Grant
    Filed: November 24, 1992
    Date of Patent: September 6, 1994
    Assignee: Ensci, Inc.
    Inventor: Thomas J. Clough