PROCESS FOR THE EXTRACTION AND PRODUCTION OF GOLD AND PLATINUM-GROUP METALS THROUGH CYANIDATION UNDER PRESSURE

• Main Authors: DE MACEDO TORRES, VANESSA, DE SOUZA COSTA, RENATO
• Format: Patent
• Language: English; French
• Published: 12.07.2005
• Edition: 6
• Subjects: CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; METALLURGY; PRETREATMENT OF RAW MATERIALS; PRODUCTION AND REFINING OF METALS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

The present invention concerns the feasibility to economically exploit or es that contain gold and platinum metals, in which the recovery of platinum metals by the conventional processes is not feasible to be employed for ores that do not present occurrences of platinum metals and mineralogically associated sulfites. The process to extract gold, silver and platinum metals from ores, concentrates and tailings according to the present invention is achieved through cyanidation under pressure, in which the material undergoes cyanidation in an autoclave with an alkaline solution (pH between 9 and 12.5), containing concentrations of cyanide between 50 and 15,000 mg/l. The temperature and the pressure are controlled within the range of 40 to 300.degree.C and 0.5 to 20 atm, respectively. Prior to the cyanidation under pressure, a cyanidation stage at room temperature can be conducted either followed or not by the adsorption of the extracted gold. After pressure cyanidation, the gold is recovered from the solution by adsorption/desorption, elutriation and electrolysis or cementation and the platinum metals by precipitation or by adsorption on the resin of the expended electrolyte.