Determination of precious metals using the neutron activation analysis technique

Abstract

Samples of residual sands were analyzed for precious metals content. These samples were collected from one of the largest silver mines in the world with the purpose of determining the existence and quantities of precious metals. The collected samples were approximately 5 kg, taken from different sites within the deposit grounds. Each sample was passed through a sieve in order to select only the smallest particles and about 100 g per sample were obtained. Twenty samples were prepared that produced thin foils from which the samples were cut in the shape of disks.

The neutron activation analysis method (NAA) was used in this work, using a nuclear reactor (Triga Mark III) as a neutron source and a high-purity germanium detector as spectrometer. The results from the analysis of this study are satisfactory; the main precious metals found were Au, Ru, Os, and Ir. A commercial study is necessary to determine if the exploitation of these sands is financially feasible.