St. Petersburg State University (Russia):

Petrov S. V., Ph. D. in Geology and Mineralogy, Associate Professor, s.petrov@spbu.ru

Borozdin А. P., Senior Lecturer

OOO «LIMS» (Russia):

Bederova L. L., Postgraduate (SPbSU), Deputy Director

A necessity to write this article became obvious after performance of a number of studies, related to determination of gold grade in samples. The method of preliminary separation of free gold by gravity methods with subsequent fire assay of dried concentrate and tailings appears to be less effective, than the screen-analysis method, described in this work. The proposed method provides for application of different techniques for separation of large gold grains and separate analysis of ground material. Ground material is screened, then oversize and undersize are subjected to fire assay. Gold grade in initial sample is calculated by balance equation, based on screened products analysis. By way of example of this method application, the results of gold grade determination in ore samples with large grains of native gold taken from the Golets Vysochaishiy deposit in the Irkutsk region are presented. It is noted, that application of the proposed method permits to promptly determine gold content in specimens of over 1–2 kg of mass, excluding negative effect of free gold analysis results, occurring in samples, and increase precision of the analysis performance.

The work was performed for Projects and Research of the St. Petersburg State University of the Russian Federation: 18.38.418.2015 «The geographic regularities of modern processes of soil formation and weathering in landscapes of cold regions of Eurasia, estimation of self-regeneration and regenerative transformation» and 3.38.690.2013 «The conditions for occurrence, evolution and postmagmatic transformations of minerals-concentrators of «critical metals» in complexes of intrusive and volcanic rocks».

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