smelt 1 
(smĕlt)
(smĕlt)v. smelt·ed, smelt·ing, smelts
v.tr.
To melt or fuse (ores) in order to separate the metallic constituents.
v.intr.
To melt or fuse. Used of ores.
[Dutch or Low German smelten, from Middle Dutch or Middle Low German; see mel-1 in the Appendix of Indo-European roots.]