Waste Minimization of Lead Paste and Jarosite to Recover a Silver-Rich Alloy by the Pyrometallurgical Route

Abstract

A silver-rich lead alloy was obtained through the recycling of two metallurgical wastes: these are lead paste obtained from spent lead–acid batteries and a jarosite residue obtained from the hydrometallurgical production of zinc. Mixtures of both wastes were pyrometallurgically treated with sodium carbonate in a silicon carbide crucible at 1200 °C. The alloy and slag produced were analyzed by atomic absorption spectrometry, X-ray diffraction, and scanning electron microscopy with energy-dispersive spectra. High silver recovery was obtained in a Pb-Ag alloy for a mixture ratio of 30% Na2CO3–40% lead paste–30% jarosite, reaching a silver grade of 126 ppm. The slags produced for the highest jarosite content allow the compound formation of Na2(SO4) and Na2Fe(SO4)2, which have high sulfur-fixing, avoiding SO2 release and contributing to the minimization of atmospheric pollution. The novel pyrometallurgical route addresses not only the valorization of precious metals such as silver and lead but also the reduction in accumulated industrial waste.