Ural State Mining University, Ekaterinburg, Russia:

Kozin V. Z., Head of Chair, Professor, Doctor of Engineering Sciences, gmf.dek@ursmu.ru
Komlev A. S., Senior Researcher, Candidate of Engineering Sciences, tails2002@inbox.ru

The complexity of determining the variation coefficient for the mass fraction of a useful component in the ore or concentrate is due its dependence on the mass fraction variability between product batches and the errors in sample preparation and analysis. The variation coefficients within a batch of concentrate or a specific test period (in a process flow or shift) are usually low and commensurate with the coefficients of variation associated with sampling errors, which are not taken into account under GOST 14180-80. The variation coefficients between individual batches or shifts are scattered, which requires calculation and application of averaged values for extended work periods or large numbers of batches. In order to eliminate the effects of such unknown sampling errors, the average variation coefficient per process flow should be established for test periods of one to five days within each month, and the total average variation coefficient should be calculated for N batches, where N should be selected for a convenient total shipment period, for example, one month. The use of combined samples to calculate the variation coefficient reduces the negative impact of sampling errors. As a result, the variation coefficients by flows should be estimated as average daily values during each month based on the results of current testing at the processing plants with subsequent recalculation for individual shifts.

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