Selenium Recycling in the United States in 2004

Abstract

As world population increases and the world economy expands, so does the demand for natural resources. An accurate assessment of the Nation's mineral resources must include not only the resources available in the ground but also those that become available through recycling. Supplying this information to decisionmakers is an essential part of the USGS commitment to providing the science that society needs to meet natural resource and environmental challenges. The U.S. Geological Survey is authorized by Congress to collect, analyze, and disseminate data on the domestic and international supply of and demand for minerals essential to the U.S. economy and national security. This information on mineral occurrence, production, use, and recycling helps policymakers manage resources wisely. USGS Circular 1196, "Flow Studies for Recycling Metal Commodities in the United States," presents the results of flow studies for recycling 26 metal commodities, from aluminum to zinc. These metals are a key component of the U.S. economy. Overall, recycling accounts for more than half of the U.S. metal supply by weight and roughly 40 percent by value.

Lost by Design

“…13 A small amount of the selenium used in photocopiers, electrical rectifiers, and solar cells is recovered and reprocessed into a secondary input material. 70 Overall, the sum of in-use dissipation and current unrecyclability for selenium reduces its potential recyclability to 30% of the element flow into use, 70 but recycling process inefficiencies shrink that potential to 1% or less. 7 Similar considerations can be extended to elements other than selenium.…”

Selenium in the environment

“…The selenium estimated content is based on copper production figures: in porphyry copper ore with 0.5% copper, the selenium content is 2.5 mg/kg, or a copper-to-selenium ratio of 2000:1. For many years, selenium production was estimated based on copper production using a factor of 0.0215% or, for very productive ores such as for example the Sudbury basin of the Ontario region, 0.064% (George & Wagner, 2009). Selenium can be present in absolute concentrations of hundreds mg/kg in tuffaceous rocks, and several g per weight Figure 1.4 Global map of active Se-ore deposits and predictive map of selenium sources associated with organic-rich depositional marine basins (modified from cent (g/100 g) in sulfides that host mercury and antimony deposits.…”

“…The substitutability of tellurium with selenium is particularly chased to lessen the criticality of supply for the much more expensive tellurium. However, this trend may revert soon from both a technical and economic standpoint since selenium is gaining increasing attention due to its critical importance in the production of solar cells (George & Wagner, 2009;Stillings, 2017). On the other hand, silicon is the major substitute for selenium in low-and medium-voltage rectifiers while new organic pigments substitute for cadmium sulfoselenide pigments.…”

“…Bismuth and tellurium are rather efficient in place of Se due to their similar chemical properties, whereas lead and cerium oxide more frequently suit as substitutes, especially in the glass-making industry, rubber production and free-machining alloys. Amorphous silicon and cadmium telluride are considered the two principal competitors for replacing Se in thin-film photovoltaic solar cells (George & Wagner, 2009). However, market fluctuations control the supply trend of prime metal vs its substitute.…”

“…As such, secondary sources for selenium recovery include coal ash, contaminated soils, municipal fly ash and bottom ash, wastewaters and sludge, landfill leachates and other anthropogenic residues. A most important source is inherently Waste Electrical and Electronic Equipment (hereafter: WEEE), such as factory scrap generated during the manufacture of selenium rectifiers, burned-out rectifiers, spent catalysts, used xerography-copying cylinders and heat-generators, outdated sensors, printed circuit boards (especially advanced microdevice graphics cards), relays, resistors (CdSe), and optical stores (George & Wagner, 2009;Schrauzer, 2004). Selenium can also be recovered from plastics and oil waste, treatment plants for phosphorus production, and abundant mining waste dumps experiencing significant selenium releases in some circumstances (Kogel, 2006).…”