Gold determination by neutron-activation method in anthropogenic waste of energy utilities companies in Primorsky Region

Elkin Oleg Ivanovich, Ivannikov Sergey Igorevich, Grebenyuk Igor Vladimirovich, Zheleznov Veniamin Viktorovich, Taskin Andrei Vasilyevich

Decrease in the flow of thermal neutrons from an neutron ampoule source based on Cf-252 inside the activation zone due to the absorption of thermal neutrons by elements contained in the sample (Fe, Ti and Mn) was shown. It was established that the active absorption of thermal neutrons by matrix elements of the sample can lead to a systematic error in the determination of elements (Au and Eu) by the instrumental neutron activation method (INAA) in samples of different elemental composition. The linear correlation of the thermal neutron flux in the center of the cell with the activated sample on the average absorption cross-section was shown. For the correct determination of elements by INAA in samples of complex and heterogeneous composition, in particular in ash and slag waste of energy utilities, amend the absorption of thermal neutrons on the basis of sample preliminary elemental analysis was proposed. It was shown that data on the fine gold content in the ash and slag waste determined by INAA method significantly higher than gold content determined by methods involving acid or assay decomposition of sample. The discrepancy in the results could be associated with the dense association of micron-sized gold particles with the surrounding minerals of ash and slag waste. It was found according to the research results that ash and slag waste of utilities contain gold in quantities that can be considered as potentially interesting for industrial extraction.

Keywords:neutron-activation analysis; waste of energy utilities; finely dispersed gold; anthropogenic deposits; ampoule neutron source.