Cut-off grade content

CUT-OFF GRADE CONTENT (EN: cut-off grade; DE: Bortgehalt; FR: teneur de coupure; ES: ley limite; RU: бортовое содержание) is the smallest content of useful component within the test sample, in case of which this sample may be included into the collection of the counted blocks for the reserves of useful minerals.

Cut-off grade content is one of the most important indicators for the conditions during the outlining of the ore bodies with fuzzy geological boundaries. The value of the cut-off grade content determines size and shape of outlined depositions with useful minerals, and average content of useful components within these depositions. The less is the cut-off grade content, the larger are the sizes of deposits, the simpler are their shapes, but the less is the average content of useful component. During the outlining of the balance reserves, the lesser limit of the cut-off grade content may be less, than the minimal industrial limit, but must exceed the content of useful component within the wastes of mining production, and must correspond to zero profitability during the extraction and processing of the ores, and for the off-balance reserves, must ensure practical possibility for the extraction of useful minerals from the mineral raw materials, which are extracted. The determination of the limit value for the cut-off grade content during the justification of conditions is performed by the method of comparison for the series of variants. As optimal, there are selected such values for the cut-off grade content, in case of which there are ensured maximal completeness for the usage of underground resources, and acceptable economic effectiveness for the mining-operational works. See also the "Reserves of useful minerals" article.