ASARCO LLC (American Smelting and Refining Company) is a mining, smelting, and refining company based in Tucson, Arizona, USA, that mines and processes primarily copper. The company is a subsidiary of Grupo México. Its three largest open-pit mines are the Mission, Silver Bell and the Ray mines in Arizona. Its mines produce 350,000,000 to 400,000,000 pounds (159,000,000 to 181,000,000 kg) of copper a year. Asarco conducts solvent extraction and electrowinning at the Ray and Silver Bell mines in Pima County, Arizona and Pinal County, Arizona and a smelter in Hayden, Arizona. Before its smelting plant in El Paso, Texas was suspended in 1999 and then demolished in April 13, 2013, it was producing 1,000,000,000 pounds (454,000,000 kg) of anodes each year. Refining at the mines as well as at a copper refinery in Amarillo, Texas produce 375,000,000 pounds (170,000,000 kg) of refined copper each year. Asarcos hourly workers are primarily represented by the United Steelworkers.