Deaf rock
Deaf rock , also known as mass , mountains (especially in coal mining ), overburden , intermediate materials (in open-cast mining ), separating works or secondary rock (in ore mining), denotes rock that cannot be used in miners' language .
In order to mine ore deposits, it is inevitable to also remove the surrounding rock. In addition, numerous shafts are necessary for mining operations to reach the ore veins .
Coal seams, too, are usually not sharply delimited, or waste rock is also stored that is also produced during mining. The mountains then have to be separated from the coal in the coal washing plant .
In the case of opencast mining, the overburden must also be cleared in order to get to the coal. Each time it is excavated, therefore, waste rock is produced, which is then stored in the dump . This material is partly used again to fill the shafts or the remaining open pit holes .
In ore mining , the art of the miners demands that ore and waste rock are separated cleanly as early as possible during mining in order to obtain a low slag content in the smelting process . Depending on the value and availability of the metal to be extracted, an ore content of more than 50% for iron ores up to a few ppm for z. B. Gold worthwhile.
Old rock heaps are partially reprocessed at a later time, as ores contained in them that could not be separated with the former methods can now be extracted economically.
literature
- Mining Lexicon . In: Hermann Franke, Hans Grothe (ed.): Lueger Lexikon der Technik . 4th completely revised and expanded edition. tape 4 . Deutsche Verlags-Anstalt, Stuttgart 1962, p. 553 .