process is described as being advantageous for recovery of gold and silver from difficult-to-treat ores such as those contaminated by copper and/or manganese. The stripped ammonium thiosulfate solution is then rejuvenated and can be recycled for re-use. After the lixiviation has been completed, recovery of the precious metals from the leach liquor is carried out using techniques that are conventional for recovering precious metals from cyanide solutions, such as by use of metallic zinc, iron or copper, by electrolysis, or by the addition of soluble sulfides to recover a sulfide precipitate. 4,070,182 by describing a process in which the difficult-to-treat ores are treated by lixiviation in ammonium thiosulfate solutions containing copper with at least a trace of sulfite ions to extract gold and silver. Furthermore, the foregoing patent provides no guidance with respect to the extraction of precious metals from difficult, raw untreated ores, and more importantly, ores containing manganese. That patent does not clearly teach the necessity of maintaining an alkaline pH in the thiosulfate leach liquor when starting with a raw ore, although the need for an alkaline pH is mentioned in conjunction with thiosulfate extraction following a copper recovery leach. The treatment of raw ores generally requires more time for a satisfactory recovery than is allowed in treating the sulfidic concentrates or residues Cs described in U.S. A time-related instability causing loss of recovery is mentioned but no reason therefore is suggested, nor is any solution proposed. 4,070,182 appears to provide no suggestion as to how to maintain the thiosulfate radical stable, and it does not even appear to recognize the problem of thiosulfate instability. 3 of that patent shows a flow diagram for the extraction of precious metals from chalcopyrite concentrate before the main leaching step for extraction of copper. This patent proposes the use of ammonium thiosulfate as a secondary leach for recovery of silver and gold, in conjunction with a hydrometallurgical process for the recovery of copper from the copper-bearing sulfidic ore. One attempt to solve the above-identified problems is disclosed in the Genik-Sas-Berekowski et al. C22B11/04- Obtaining noble metals by wet processes.C22B- PRODUCTION AND REFINING OF METALS PRETREATMENT OF RAW MATERIALS.C22- METALLURGY FERROUS OR NON-FERROUS ALLOYS TREATMENT OF ALLOYS OR NON-FERROUS METALS.Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.) Filing date Publication date Application filed by Individual filed Critical Individual Priority to US06/754,827 priority Critical patent/US4654078A/en Application granted granted Critical Publication of US4654078A publication Critical patent/US4654078A/en Anticipated expiration legal-status Critical Status Expired - Fee Related legal-status Critical Current Links Original Assignee Individual Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.) Galaviz Current Assignee (The listed assignees may be inaccurate. ![]() Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.) Expired - Fee Related Application number US06/754,827 Inventor Ariel E. ![]() Google Patents Method for recovery of precious metals from difficult ores with copper-ammonium thiosulfateÄownload PDF Info Publication number US4654078A US4654078A US06/754,827 US75482785A US4654078A US 4654078 A US4654078 A US 4654078A US 75482785 A US75482785 A US 75482785A US 4654078 A US4654078 A US 4654078A Authority US United States Prior art keywords copper solution ammonium thiosulfate lixiviating sub Prior art date Legal status (The legal status is an assumption and is not a legal conclusion. ![]() Google Patents US4654078A - Method for recovery of precious metals from difficult ores with copper-ammonium thiosulfate US4654078A - Method for recovery of precious metals from difficult ores with copper-ammonium thiosulfate
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