Ural State Mining University (Russia):

Kozin V. Z., Head of Chair, Doctor of Engineering, Professor, gmf.dek@ursmu.ru

Vodovozov K. A., Lecturer, gmf.opi@ursmu.ru

Imbalances in commercial stock of a concentrating mill may never be zero; therefore there is a need to specify its admissible limits. A commonly known relative imbalance value is equal to ±2% referenced, inter alia, in the nature conservation regulations for mineral processing operations. However, most real-life imbalances do not fit within these limits, and for ores with a minor mass fraction of component different limits of admissible imbalances are prescribed, e. g. ±5 %. For ores with an extremely low mass fraction of component (gold, diamonds, etc.) the admissible imbalance limits are not available. The article presents equations to enable calculation of constituents of the commercial stock imbalance error on a case-by-case basis for any mill and specifically for each ore component. It also indicates limits for admissible imbalance random error, which are related to the coefficient of variation. The systematic error of imbalances depends on the proportion of results dismissed during the analysis. The probable systematic error of an imbalance is a function of the skipped peaks in the mass fraction of the flows of ore feed and concentrates. As a result the admissible imbalance error becomes predominantly either positive or negative.

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