Determination of indium in its mineral resources by comparator neutron activation analysis

Abstract

The application of comparator instrumental neutron activation analysis (INAA) was considered to determine indium by the short-lived radionuclide ^116mIn it its mineral resources such as different types of polymetallic ore, copper, lead-zinc, tin, tin-tungsten ores, and similar. Cu and Zn contents of the samples were determined by X-ray fluorescence method (XRF) using a laboratory energy dispersive XRF spectrometer RLP-21T, Kazakhstan. If Cu mass fraction exceeded 0.4–0.5% or that of Zn exceeded 3% (that is often characteristic of polymetallic, copper, and lead-zinc ores), then their contents were used in comparator INAA as the internal standards measured by an independent method. If none of the conditions were met, then the standard addition method was applied using a 10 mg addition of reagent ZnO to each sample. A range of the samples of polymetallic ore reference material certified for indium content (CRMs) were used to verify accuracy of the method. The proposed variant of comparator INAA was shown to insure accuracy of a routine analysis of indium-bearing ores of nonferrous metals fir indium content by the III category of precision according to the industrial standard OST 41-08-221-04 (Russian Federation). The method was tried out for several dozens of ore samples presenting various indium mineral resources including the ones from the gold-polymetallic deposit Maikain in North-Eastern Kazakhstan