Evaluation of the reduction factor for the determination of gold in ores by epithermal neutron activation analysis

Abstract

The underestimation (or reduction factor) of gold (¹⁹⁸Au) in ore samples due to the self-shielding of epithermal neutrons during epithermal neutron activation analysis (ENAA) was measured. Three synthetic ores with different size ranges of gold particles were prepared and analysed by NAA and ENAA. Epithermal neutron activation analysis was found to underestimate gold in synthetic ores containing gold particles with size ranges of ⩽53, 53–150 and 150–250 µm by the factors 11, 31 and 33%, respectively, in comparison with NAA. A reduction factor of 5% was also measured for gold in reference ore MA-1, certified by CANMET Canada, with 80% of particles below 37 µm.