Precious metals quantification in industrial waste matrices using nuclear reactor based NAA methodologies

The precious metals gold (Au) and silver (Ag) are present at trace levels (parts per million, i.e., mg kg^-1) in various copper based industrial waste matrices. Accurate assessment of concentrations is the stepping stone for devising appropriate separation /beneficiation strategies, essentially aiming at these precious metals. Method for the determination of the noble metals after separation from copper based materials was elaborated by Remya et.al. One of the most sensitive methods for the analysis of noble elements in ores/waste is neutron-activation analysis (NAA). Au and Ag were determined in various copper based industrial waste matrices like copper concentrate, dross and Cu metal by NAA, using appropriate neutron irradiation facilities such as Dhruva, AHWR Critical facility and earlier in Apsara reactor. Based on the sample amounts, expected precious metal contents and the neutron fluxes in various irradiation facilities, sample matrices were separated either before (Chemical NAA: CNAA) or after irradiations (Radiochemical NAA: RNAA). Quantifications were done by relative as well as internal mono standard NAA methodologies