slag heap

plural slag heaps · alternative slag-heap · alternative slagheap

1. A man-made mound or heap formed from the waste material (slag) that is a by-product of coal mining, or the waste by-product from a foundry or furnace.

   As the Lothian Plain is reached, collieries and slag heaps begin to appear, although much of the surrounding country remains unspoiled.

   1952 January, H. A. Vallance, “The Waverley Route”, in Railway Magazine, page 16

   1 more example

   The Borinage coalfield around Mons is another attractive area for the railway enthusiast; it is rather like South Lancashire, with its gently undulating landscape studded with slag heaps and pithead gear and criss-crossed by railway lines and tramways.

   1960 February, J. N. Faulkner, “The Belgian Railways today”, in Trains Illustrated, page 86

   Synonyms: spoil heap