Mercury
Domestic production and use
- Mercury was shaped as a byproduct from several gold-silver mines in Nevada; however, byproduct manufacture data were not reported. Mercury has not been formed as a primary mineral commodity in the United States since 1992, when the McDermitt Mine in Nevada closed. Processing of calomel, a mercury-chlorine compound obtained from domestic and foreign mines, is another source of mercury.
- Retorting end-of-use mercury-containing products, such as batteries, dental amalgam, and fluorescent lamps, and mercury contaminated soils, provided another source of mercury. The domestic chlorine-caustic soda industry was the leading end user of mercury. Some of the mercury used at these facilities was recycled in-plant; however, approximately 100 tons of replacement mercury is purchased yearly.
- Some mercury-containing chlor-alkali waste, as “amalgam” (not chemically defined), was exported to Canada and landfilled. Mercury use has declined in the United States because of mercury toxicity.
Recycling
In 2007, five companies accounted for the majority of secondary mercury reclamation and manufacture. Smaller companies collected dental amalgam, barometers, computers, gym flooring, manometers, thermometers, thermostats, and some mercury-containing toys and moved them on to larger companies for retorting. The reservoir of mercury-containing products for recycling is decrease because of increased use of nonmercury substitute devices
Substitutes
Many dentists use ceramic composites as substitutes for mercury-containing dental amalgam for esthetic and human health concerns. “Galistan,” an alloy of gallium, indium, and tin, or alternatively, digital thermometers, now replaces the mercury used in thermometers. At chlorine-caustic soda plants, mercury-cell technology is being replace by newer diaphragm and membrane cell technology. Light-emitting diodes (LEDs) that contain indium, such as those used at the Thomas Jefferson Memorial in Washington, DC, substitute for mercury-containing fluorescent lamps.
World Resources
China, Kyrgyzstan, Russia, Slovenia, Spain, and Ukraine have most of the world’s predictable 600,000 tons of mercury resources. Spain, once a leading producer of mercury from its centuries-old Almaden Mine, stopped mining in 2003, and making is from stockpiled or recycled material. In the United States, there are mercury occurrences in Alaska, Arkansas, California, Nevada, and Texas.
