Concept
A spoil tip (also called a boney pile, culm bank, gob pile, waste tip or bing) is a pile built of accumulated spoil – waste material removed during mining. These waste materials are typically composed of shale, as well as smaller quantities of Carboniferous sandstone and other residues. Spoil tips are not formed of slag, but in some areas, such as England and Wales, they are referred to as slag heaps. In Scotland the word bing is used. The term "spoil" is also used to refer to material removed when digging a foundation, tunnel, or other large excavation. Such material may be ordinary soil and rocks (after separation of coal from waste), or may be heavily contaminated with chemical waste, determining how it may be disposed of. Clean spoil may be used for land reclamation. Spoil is distinct from tailings, which is the processed material that remains after the valuable components have been extracted from ore. The phrase originates from the French word espoilelier, a verb conveying the meaning: to seize by violence, to plunder, to take by force. Spoil tips may be conical in shape, and can appear as conspicuous features of the landscape, or they may be much flatter and eroded, especially if vegetation has established itself. In Loos-en-Gohelle, in the former mining area of Pas-de-Calais, France, are a series of five very perfect cones, of which two rise from the plain. Most commonly the term is used for the piles of waste earth materials removed during an excavation process. In surface mining (commonly called strip mining) for coal or other underground deposits, earth materials removed to expose the targeted deposit are piled up alongside the excavation site (commonly a strip mining pit) in spoil banks. A dredge in placer mining is used to dig up volumes of gravel and other earth materials, which are sent through sluices to remove gold or other minerals, and the remaining earth materials ("tailings") are deposited behind the dredge in spoil banks.