A refining step in lead smelting where bismuth is stripped from the molten lead bullion. This is typically done using the Kroll-Betterton process, which involves adding calcium and magnesium to the melt. These alkaline earth metals react with the bismuth to form a solid dross that floats to the surface and is skimmed off.
Heard on the job
The bullion is still out of spec, so we've to run another round of debismuthization before casting the pigs.