Hayden Smelter, Arizona

Part of Asarco's "Ray Complex," this copper smelter processes ore from the company's copper mines in the region (the Ray Mine, Silver Bell Mine, and Mission Mine). Copper concentrate arrives from the mines (the nearest being 20 miles away) by rail, and is processed into 99% pure copper anodes, each weighing 750 pounds. The anodes are shipped to the company's refinery in Amarillo, Texas for further finishing. The first part of the Hayden Plant was built in 1912, and the plant now covers 200 built-up acres, dominated by the huge 1,000-foot-tall stack. In 2015, as part of a settlement with the federal government, Asarco agreed to pay $150 million in fines and remediation costs due to emission control violations. Also in 2015, Asarco announced that it would be closing the Hayden concentrator for an unspecified length of time, due to plummeting copper prices.