Gangue

Waste rock, even mass, mountains (especially in the coal mining), overburden or intermediate means ( open pit ) or vagina factory and surrounding rock called ( in ore mining ), referred to in the miners' language rock, which is not recyclable.

In order to reduce mineral deposits, it can not be avoided, to also remove the rock about lying with him. In addition, many wells are needed for the mining operation in order to penetrate to the ore veins.

Even coal seams are usually not sharply defined or it is waste rock stored with that obtained with the degradation. The mountains must then be separated in the coal washing of the coal.

Likewise, the overburden must be cleared at the open pit only to get to the coal. Thus, at each reduction falls to waste rock, which is then stockpiled. Some of this material is re-used for filling the pits or opencast mining holes.

In metal mining, it requires the art of miners to possibly see to the degradation for a clean separation of ore and waste rock to get a small share in the smelting slag. Depending on the value of the ores is a reduction to 0.1 % in relation to the ore gangue worthwhile for very expensive ores even up to even less.

Old tailings areas to be worked up at a later time partially because contained in them, with the former methods are not separable ores are now to gain economically.