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Silver recovery from dental amalgam wastes


Material Science & Engineering International Journal
Emre YILMAZ,1 Selim ERTURK,1 Cuneyt ARSLAN,1 Fatma ARSLAN2

Abstract

Alloys produced with mercury and other metals are called amalgam. Dental amalgams are important alloys and contain 40-50% mercury with the addition of silver (22-39%), tin (12-18%) and copper (2-18%). Therefore, these amalgams have high economic value and need to be evaluated. This experimental study deals with recovering their metal contents by physical and chemical separation techniques. Within the framework of this study, distilled non-contact dental amalgam wastes were subjected to size reduction, leaching with nitric acid and cementation with copper. Leach liquor was filtered and both solution and leach residue were characterized. Results have shown that, leaching efficiency was above 99.8% and leach solution contained 16 g/L Ag+, and 8.5 g/L Cu2+ ions. Later, silver was recovered from solution by cementation with copper. The basic parameters in the cementation experiments, such as cementator quantity, stirring speed, pH, and temperature were examined. Cementation efficiency reached above 99.9% and chemical analysis has shown that silver concentration of solution decreased from 16g/L to 1.7 mg/L.

Keywords

dental amalgam, silver, acid leaching, cementation

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