Slag

n.	1.	The dross, or recrement, of a metal; also, vitrified cinders.
	2.	The scoria of a volcano.
	3.	(Metal.) A product of smelting, containing, mostly as silicates, the substances not sought to be produced as matte or metal, and having a lower specific gravity than the latter; - called also, esp. in iron smelting, cinder. The slag of iron blast furnaces is essentially silicate of calcium, magnesium, and aluminium; that of lead and copper smelting furnaces contains iron. Slag furnace (Metal.) a furnace, or hearth, for extracting lead from slags or poor ore. Slag wool mineral wool. See under Mineral.
v. i. & t.	1.	(Metal.) To form, or form into, a slag; to agglomerate when heated below the fusion point. [imp. & p. p. Slagged ; p. pr. & vb. n. Slagging.]

Noun

1.

slag - the scum formed by oxidation at the surface of molten metals Synonyms: scoria, dross

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