The Collaborative International Dictionary of English v.0.48:

Smelt \Smelt\, v. t. [imp. & p. p. Smelted; p. pr. & vb. n.
   Smelting.] [Of foreign origin; cf. Sw. sm[aum]lta, D.
   smelten, Dan. smelte, Icel. smelta, G. schmelzen OHG.
   smelzan, smelzen; probably akin to Gr. ?????. Cf. Enamel,
   Melt, Mute, v. i., Smalt.] (Metal.)
   To melt or fuse, as, ore, for the purpose of separating and
   refining the metal; hence, to reduce; to refine; to flux or
   scorify; as, to smelt tin.
   [1913 Webster]