Abstract:According to the study of enriching precious metals by lead, the concept of twice enrichment was first proposed, the testing method of gold and silver in gold mud was established. Recoveries of gold and silver were calculated based on accurate gold and silver values measured with the application of classical fire assay. The influence of the amount of lead foil, sample volume, ash blowing temperature and lead foil covering mode on the recoveries of gold and silver were discussed and the optimal technological conditions for direct ash blowing high grade gold mud were also obtained. Under the optimum conditions, comparative experiments of direct cupellation method and fire assay method were also conducted using high-grade gold mud prepared by cyanide-displacement method, the results show that direct cupellation method conformed to the results of fire assay, the recovery of gold was 99.84-100.12%, RSD ≤0.10% and the recovery of silver was 99.41-100.66, RSD≤0.40%. The direct cupellation method is simple, rapid and accurate, requiring lower labor intensity.