- Slag heap
A slag heap (also called bing, Boney piles, culm, waste coal, Terekons (Russian), gob piles, or slate dumps) is a pile built of accumulated
tailings, which are by-products of mining. These waste materials are mostly composed of shale, as well as smaller quantities of carboniferous sandstoneand various other residues.
Slag heaps may be conical in shape, hence appearing as conspicuous features of the
landscape, or they may be much flatter and eroded, especially if vegetation is established thereon. The highest in Europe is in Loos-en-Gohellein the former mining area of Pas-de-Calais. It comprises a range of five cones, of which two reach 180m (590 ft), surpassing the highest peak in Flanders, Mont Cassel.
The oldest coal-based slag heaps may still contain enough
coalto begin spontaneous slow combustion. This results in a form of vitrificationof the shale, which then acquires sufficient mechanical strength to be of use in road construction. Some can therefore have a new life in being thus exploited; for example, the flattened pile of residue from the 11/19 site of Loos-en-Gohelle. Conversely, others are painstakingly preserved on account of their ecological wealth. With the passage of time, they become colonised with a variety of floraand fauna, sometimes foreign to the region. This diversity follows the mining exploitation. For example, because the miners threw their apple or pear cores into the wagons, the slag heaps became colonised with now more or less forgotten varieties of fruit trees. One can even observe the proliferation of buckler-leaved sorrel (French sorrel - Rumexscutatus), the seeds of which have been carried within the cracks in the pine timber used in the mines. Furthermore, on account of its dark colour, the South face of the slag heap is significantly warmer than its surroundings, which contributes to the diverse ecology of the area. In this way, the slag heap of Pinchonvalles, at Avion, hosts 200 different varieties of higher plants. Some thirty species of birds nest there.
Some cultivate vines, as in the case of slag heap No7 of the coal-mining region of
Mariemont-Bascoupnear Chapelle-lez-Herlaimont(province of Hainaut) which produces some 3,000 litres of wine each year.
Finally, some slag heaps provide for various sporting activities. The slopes of the slag heaps of 11/19 at
Loos-en-Gohelle, or again, at Noeux-les-Mines, are used for winter sports, for example skiand luge, since the provision of a pisteon the flank of the heap.
Belgium, a long distance footpathalong the slag heaps ( _fr. terrils) (GR-412, "Sentier des terrils") has been opened in 2005. It leads from Bernissartin western Hainaut to Blegnyin the province of Liège.
United States, mining companies have not been allowed to leave behind abandoned piles since the Surface Mining Control and Reclamation Act was passed in 1977.
The future for slag heaps
The question of re-utilisation of slag heaps is sometimes raised.
Noeux-les-Mines, an artificial skislope has been provided on an old slag heap, the building of which has provided it with a novel use.
* Because they are inappropriate for building purposes, old slag heaps can be partially revegetated and provide valuable green spaces.
* Some slag heaps contain residual coal and evolving techniques allow renewed exploitation of this asset.
* There has also been research into various slag
recyclingtechniques, which result in slag being removed from the heap site and potentially used for other commercial or construction purposes.
Heaps sometimes grew to millions of tons, and, having been abandoned, remain as huge piles today. They trap solar heat, making it difficult (although not impossible) for
vegetationto take root; this encourages erosion and creates dangerous, unstable slopes. Existing techniques for regreening slag heaps include the use of geotextiles to control erosion as the site is resoiled and simple vegetation such as grassis seeded on the slope.
The piles also create acid rock drainage, which pollutes streams and rivers.
As some slag heaps resulting from industries such as coal or oil shale production can contain a relatively high proportion of hydrocarbons, they can commence spontaneous subterranean combustion, which can be followed by surface fires.
Such fires can follow slow combustion of residual hydrocarbons. Their extinction can require complete encasement, which can prove impossible for technical and financial reasons. Sprinkling is generally ineffective and injecting water under pressure counter-productive, because it carries oxygen, bringing the risk of explosion.
The weak environmental and public health impact of these fires leads generally to waiting for their natural extinction, which can take a number of decades.
With slag heaps there is a danger of
landslip. An example was the Aberfan disaster, of Friday, 21 October 1966, in which a total 144 people were killed, 116 of whom were school children, mostly between the ages of 7 and 10. Five teachers also died in the accident.
* [http://gohelle.free.fr/terrils/loos/loos.htm Spoil heap 11/19 in Loos-en-Gohelle] (in French)
* http://chaine.des.terrils.free.fr (in French)
* http://www.terrils.be/ (in English,French,German,Italian)
* http://www.land-art-charleroi.be/index_eng.html (contest of Land Art on the Slag Heap of Charleroi, Belgium)
* [http://www.energybulletin.net/2453.html Turning coal waste into light] ,
8 October 2004
* [http://www.dep.state.pa.us/dep/deputate/minres/bmr/historicalminingreports/historicalpictures/pic067.htm Photo of a typical coal breaker with culm bank]
* [http://amp.wpcamr.org/archives/33 Breaker Boys and Bony Pickers] , 28 November 2006
Wikimedia Foundation. 2010.
Look at other dictionaries:
slag heap — noun A small hill of coalmining waste • • • Main Entry: ↑slag * * * slag heap UK US noun [countable] [singular slag heap plural slag heaps … Useful english dictionary
slag heap — slag heaps also slagheap N COUNT A slag heap is a hill made from waste material, such as rock and mud, left over from mining. [mainly BRIT] … English dictionary
slag heap — n especially BrE a pile of waste materials at a mine or factory … Dictionary of contemporary English
slag heap — slag ,heap noun count a large pile of waste produced after coal or a metal has been taken out of the earth and processed … Usage of the words and phrases in modern English
slag heap — ► NOUN ▪ a hill or area of refuse from a mine or industrial site … English terms dictionary
slag heap — UK / US noun [countable] Word forms slag heap : singular slag heap plural slag heaps a large pile of waste produced after coal or a metal has been taken out of the earth and processed … English dictionary
slag heap — noun A man made mound or heap formed with the waste material (slag) as a by product of coal mining. Can also refer to the waste by product from a foundry or furnace, formed into such a mound … Wiktionary
slag heap — mound of residue of ore separated from a metal during the smelting process … English contemporary dictionary
slag heap — noun a hill or area of refuse from a mine or industrial site … English new terms dictionary
slag heap — noun (C) especially BrE a pile of waste material at a mine or factory … Longman dictionary of contemporary English