PRECIOUS METALS

ASARCO LLC is one of the world's leading producers of copper, with mines, smelters, and refineries located in several states.   The silver and gold Asarco produces occur in nature in combination with other metallic elements that require complex metallurgical processes to recover.

Mining

Most of the silver and gold reserves in the United States are in ores which also contain other metals such as copper, lead, and zinc.

Thus, a large portion of silver and gold refined each year in the United States is a by-product of copper, lead, and zinc production. Asarco also purchases concentrates containing silver and gold from other mining companies.

Refining Concentrates bearing precious metals are processed at Asarco's copper smelters into blister copper. The silver and gold are present in this intermediate product as impurities. The blister copper is sent to Asarco's Amarillo Copper Refinery in Texas. As the copper is refined in electrolytic cells, the silver, gold, and other impurities settle to the bottom of the cells. This sediment is recovered as feed for Asarco's precious metals refinery.

Asarco's precious metals refinery is located within the copper refinery complex in Amarillo. Here, the sediment from the copper refining tanks and the precious-metal-bearing scrap purchased on the open market are processed and electrolytically refined. The refinery has the capacity to produce 600,000 troy ounces of gold and 60 million troy ounces of silver per year.