Ural State Mining University (Ekaterinburg, Russia)
Kozin V. Z., Dean, Doctor of Engineering Sciences, Professor, gmf.dek@ursmu.ru
Komlev A. S., Senior Researcher, Doctor of Engineering Sciences, tails2002@inbox.ru

The maximum grain size of valuable minerals is a key parameter in ore characterization, frequently cited in technological regulations and mineral processing literature. This value is typically established through mineralogical analysis of narrow size fractions, with the largest grain observed in the sample taken as the maximum. Theoretically, it is impossible to detect the largest grain present in the ore using a sample; instead, attention should be given to the proportion of large grains contained in the ore. Practical determination of the proportion of liberated grains depending on sample size showed that, for the same ore, larger grains are found in concentrate samples than in ore samples, and larger grains are found in ore samples than in tailings samples. To reliably determine maximum grain sizes, ore samples should be enriched so that the concentrate contains 0.1–1 % valuable minerals by mass. Examination of 10,000 to 100,000 grains is recommended, with the three largest liberated grains identified. Analysis of the relationship between mineral liberation and grain size reveals that the observed maximum grain size decreases as the mass fraction of valuable minerals and the sample mass decrease. For mineralogical analysis of a sample containing 500 grains, the lower detection limit corresponds to a valuable mineral mass fraction of 0.6 %. For operational plants, the maximum grain size of valuable minerals should be determined using concentrate samples from the largest available size class, with an assessment of 10,000 to 100,000 concentrate particles.

The study was supported by the Ministry of Science and Higher Education of the Russian Federation in accordance with state assignment for the Ural State Mining University No. 0833-2023-0004.

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