Production. Tin smelting. Tin is recovered from smelting furnace smoke in a Southern operation that produces pure tin from South American ore. All the smoke from the furnace is carried by long tubes to Cottrell precipitating units as shown. Here an electrical current of 65,000 volts throws out all the tin held in the smoke, and makes a valuable addition to the supplies of tin now needed for the countless critical war uses of the United Nations