Anaconda smelter, Montana. Anaconda Copper Mining Company. Poling in the refining furnace. Wooden pole are plunged into the molten copper; there is a great evolution of gases when this is done and the excess oxygen combines with the carbon of the the wood and passes off as carbon monoxide. This refining of blister copper is based upon the fact that oxygen has a stronger affinity for the impurities in the charge that it has for copper