Accurate determination of platinum, palladium, gold and silver in ores and concentrates by wet chemical analysis of the lead assay button

Abstract

A combined fire assay-wet chemical procedure for the accurate and rapid determination of platinum, palladium, gold and silver is described. The sample is fused with lead flux and the lead button is parted with perchloric acid after heating at 180–190 °C. After dilution of the parting solution with water, a formic acid reduction step is applied for the selective group precipitation of the four noble metals. After filtration, the precipitate is dissolved in aqua regia and the noble metals are determined by atomic absorption spectrometry. The proposed method was applied to a variety of sample types and, compared with the classical lead cupellation method, showed greater accuracy and precision in all instances.