JSC «Matrosov Mine» (JSC «Polyus») (Magadan, Russia):

Nikitenko E. M., Deputy Director, Candidate of Engineering Sciences

LLC «STC «Magnetic Fluids» (Naro-Fominsk, Russia):

Evtushenko M. B., Director, Candidate of Engineering Sciences

NUST MISIS (Moscow, Russia):

Yushina T. I., Head of Chair, Candidate of Engineering Sciences, Associate Professor, yuti62@mail.ru

Most of the gold-bearing black shale deposits of Northeastern Russia are characterized by extensive reserves of relatively low-grade ores. Integrated development of these deposits may increase their profitability. Platinum-group metals (PGMs) may be regarded as associated components, with their presence at the levels of 0.01 to 0.08 g/t having been established a long time ago. These deposits feature large amounts of free gold, including in coarse lumps, which negatively affects the quality of respective geological exploration. In order to reliably establish both gold and PGM grades for the ores of these deposits, the mass of the sample analyzed must be increased several times, free gold from the entire sample mass must be recovered into the gravity concentrate at the sample preparation stage, and a fire assay must be conducted for the concentrate and the tailings. This method was used to analyze samples from the Degdekan deposit. The results demonstrate that, in addition to obtaining reliable gold grade values, the application of ferrohydrostatic (FGS) separation at the stage of gravity concentration enables registering PGMs in the fire assay beads by X-ray fluorescence analysis and ICP-MS. In this manner, with the Degdekan deposit as an example, it is shown that a reliable analysis of PGM grades in gold-bearing black shale ores and an assessment of the possibility of their associated mining require a significant increase in the mass of the sample analyzed, its preliminary concentration, and replacement of the gravimetric finish of the assay with the instrumental finish.

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