METHOD OF RECOVERING SILVER FROM SILVER-CONTAINING SCRAP

• Main Authors: KUZ'MIN A.P, KALINNIKOV V.T, GROMOV O.G, LOKSHIN EH.P, KUNSHINA G.B
• Format: Patent
• Language: English
• Published: 27.04.1998
• Edition: 6
• Subjects: CHEMISTRY; CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION ORPROCESSING OF GOODS; FERROUS OR NON-FERROUS ALLOYS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; METALLURGY; PRETREATMENT OF RAW MATERIALS; PRODUCTION AND REFINING OF METALS; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINSTCLIMATE CHANGE; TREATMENT OF ALLOYS OR NON-FERROUS METALS

FIELD: precious metal recovery. SUBSTANCE: method is intended for recovering silver from the scrap of electronic and electrotechnical ware containing silver coatings based on brass, beryllium brasses, and pure copper. Scrap is treated with mixture of concentrated sulfuric and nitric acids with 5.0-15.5 vol % of the latter. Treatment is carried out at 30-50 C for 4 to 15 min under mechanical stirring and bubbling reaction medium by compressed air. Desilvered scrap is separated from reaction solution, which is then diluted with 1.5-2 volumes of water. Silver sulfate precipitate obtained is filtered off from mother solution, dried, caked with potassium hydroxide to produce powdered silver metal. Mother solution can be evaporated to form concentrated sulfuric acid, corrected in respect to nitric acid, and returned into the beginning of process. Selective and complete recovery of silver from scrap is accomplished at temperature reduced by 30-50 C, and duration of acid treatment is 2- 7-fold shortened. EFFECT: enhanced efficiency of silver recovery. 3 cls