Mineral Loss

the part of potential reserves of solid useful minerals that is not extracted from the interior of the earth when a deposit is worked. Losses are subdivided into general mine losses (pits, shaft, and placer) and operating losses. General mine losses include losses in bottom pillars, near major mine excavations and wells, in barrier pillars between mines, and under buildings, engineering and farming structures, communication lines, bodies of water, aquifers, and prohibited zones. Operating losses are subdivided into losses in the main body and those in mineral bodies removed from the main body. Operating losses of the first type include reserves left in pillars within excavated sectors; in flat and hanging walls; at tapering-out points and on flanks; in burning, flooded, and caved-in sectors; and near tectonic displacements. Operating losses of the second type are incurred during combined extraction and mixing with the enclosing rock; in slides, cave-ins, and flooding; at loading, unloading, storage, and sorting points; and on the transport routes of mining enterprises.

Mineral losses are computed in units of weight and in terms of percentage. General mine losses are given in relation to total balance reserves of the mine (pit or placer), whereas operating losses are given in relation to depleted balance reserves. All industrially important mineral components in composite ores are taken into account. Losses are determined by on-site measurements or by mine surveyor maps and cross sections with reliable delineation and sampling of the mineral deposits or stripping sectors. Indirect methods are used when direct methods are not possible and include comparing the amount of mineral product in depleted balance reserves to extracted bulk ore.

In the USSR, records of mineral losses must be kept by all mining enterprises.