Gold and silver analysis by fire assay using copper as a collector

Fire assay is a well-known analytical technique widely used for content determination of gold, silver, and PGM in ores, concentrates, slags, and other metallurgical products. Traditional fire assay for gold ores and concentrates require roasting of the material prior to fusion, and the use of lead as a collector of the precious metals. Lead has a low melting temperature of about 600 K and is an excellent collector for gold and silver; for these reasons, lead is the preferred collector used in fire assay. This paper presents the results of using copper, added as Cu(OH)₂, as a collector for said metals. The tested material is a sulphide concentrate with high gold and silver content. Results obtained show that, under appropriate conditions, the amount of precious metals collected by copper are the same as the amount collected by lead; thus, Cu may be a suitable replacement for Pb as a collector in fire assay analysis for these type of materials.