RECOVERY OF SILVER FROM WASTE SILVER OXIDE BUTTON CELLS PART I: CHARACTERIZATION OF ACTIVE MATERIAL

Global silver mine production fell 2 percent in 2018, registering the third consecutive annual decline. Concurrently, metal demand is increasing; the demand for the photographic industry - the largest consumer - is increasing after the economic shock produced by the appearance of digital formats (Kodak - company under bankruptcy protection procedure between 2012 and 2013 announces increasing sales of films). Demand for contactors and conductors (15%), brazing alloys (7%), catalysts batteries (3%) also increases. Under these circumstances, the concerns to recover silver from all secondary sources become a necessity. Although the amount of silver used is minimal and not a significant contributor to the product cost, due to the huge amount of such batteries continuously produced, the recovery of silver is required. In the present work, button cell batteries with silver content were sectioned, separated (paste from the metal casing) in an ultrasonic bath and the resulting paste was analyzed to identify the constituents in order to subsequently establish the silver recovery technology. The samples were analyzed by SEM (Quanta Inspect F50, with a field emission gun - FEG with 1.2 nm resolution and an Energy Dispersive X-ray Spectrometer - EDX having 133 eV resolutions at MnK alpha). XRD data were obtained using a Panalytical X'PERT MPD X-ray diffractometer with a Cu K-alpha radiation source (lambda = 1.5418 angstrom) in the range 2 theta = 10-90 degrees. In the second part of the paper we will study the recovery of silver from active paste by leaching processes in nitric acid (HNO3) followed by precipitation of silver chloride (AgCl) and finally the melting of AgCl with Na2CO3 flux.