Drossing Furnace

The drossing furnace is used in Cominco's Trail Operations for lead production. Lead bullion is tapped from the furnace crucible, by launder, to the Continuous Drossing Furnace where the lead is purified by removing copper, arsenic, and antimony.

By cooling the bullion from 900ºC to 400ºC, a copper matte is formed and rises to the surface where it is skimmed for processing in the Copper Products Plant. In a subsequent step called the "softening stage," oxygen is used to oxidize arsenic and antimony to form a slag which can be removed from the surface of the bullion. After purification, bullion is poured into 5 tonne ingots and transferred to the Lead Refinery for electro-refining.

In the photograph below is the Drossing Plant in the Lead Smelter building. The Drossing Plant removes copper from the lead bullion before it is sent for final refining.

Drossing Plant

Button Pouring

As seen in the photo at left, lead bullion is poured into "buttons" for transport to the lead refinery where electro-refining will remove silver, gold, bismuth and other metals from the lead for further refining. The resulting refined lead is then ready for shipment to customers.