Answer:

slags

Answer	Crossword Clue
SLAGS	Smeltery wastes
SLAGS	Smelting residues
SLAGS	Forms into metallic waste

SLAGS	Converts into metallic waste
SLAGS	Metal wastes
SLAGS	Cinders.
SLAGS	Forms into dross.
SLAGS	Forms into cinders.
SLAGS	Smeltery by-products.
SLAGS	Mine wastes.
SLAGS	Smelting products.

SLAGS	Products of smelting
SLAGS	Smeltery remains
SLAGS	Smeltery leavings
SLAGS	Steel impurities
SLAGS	Smelting byproducts
SLAGS	Denigrates, in British slang
SLAGS	Becomes smelting waste
SLAGS	Smelting stuff

SLAGS	Smelter wastes
SLAGS	Smelting leftovers
SLAGS	Pittsburgh byproduct
SLAGS	Drosses
SLAGS	Cinder heaps
SLAGS	Forms a residue when smelting ore