Ural State Mining University (Russia):

Kozin V. Z., Doctor of Engineering Sciences, Professor, Head of Chair
Komlev A. S., Ph. D. in Engineering Sciences, Engineer

E-mail (common): gmf.dek@ursmu.ru

In Richards–Chechott equation of sample minimal mass, the only unknown value–coefficient k is not theory-based. This leads to different reсommendations in choice of the coefficient in the ranges from 0.2–31.0 to 0.1–1.0, depending on ore characteristics. Theoretical calculations invariably brought the authors to the power in ore lump maximum size equal to three. Acceptance of power equal to two was found admissible, but the problem of choice of the coefficient k still remained. A formula for theoretical minimal sample mass with indeterminate power b in ore lump size was obtained. This power b depends on ore texture, and in a particular case may be assumed to be equal to two, as in Richards–Chechott equation. For this case, a formula for calculation of the coefficient k has been obtained, that included size of valuable minerals impregnations in ore, valuable component mass fraction and permissible relative error in sample reduction. Calculated values of the coefficient k for copper and gold ores are presented. For copper ores with respect to relative random error of 1 % with size of impregnations being 0.5 mm and copper mass fractions from 5.0 to 0.5 %, coefficient k was in the range of 0.06–0.60. For gold ores with respect to relative error of 10 % with size of impregnations being 0.5 mm and gold grade from 10.0 to 1.0 g/t, coefficient k was in the range of 4.5–45.0. For copper ores with size of impregnations being 1.0 mm and copper mass fraction of 1.0 %, change of permissible error in reduction P_permis from 1 to 15 % leads to change of coefficient k in the range of 0.6–0.003. It was shown, that transition to index of power of 1.5 is expedient. In this case, change of the coefficient k for copper ores under the same conditions is in the range of 0.04–0.42, for gold ores – in the range of 3.2–31.8. With that, minimal masses of samples are significantly decreased.

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