Editing Tellurium (section)

==Production==
Most Te (and Se) is obtained from [[porphyry copper deposit]]s, where it occurs in trace amounts.<ref>{{cite book|chapter=Chapter 7: By-Products of Porphyry Copper and Molybdenum Deposits|first1=D. A.|last1=John|first2=R. D.|last2=Taylor|title=Rare earth and critical elements in ore deposits|year=2016|volume=18|pages=137–164|doi=10.5382/Rev.18.07 |url=https://pubs.er.usgs.gov/publication/70048652|editor=Philip L. Verplanck and Murray W. Hitzman}}</ref> The element is recovered from [[anode]] [[sludge]]s from the electrolytic refining of blister [[copper]]. It is a component of dusts from [[blast furnace]] refining of [[lead]]. Treatment of 1000 tons of copper ore yields approximately {{convert|1|kg|lb|spell=in|abbr=off}} of tellurium.<ref>{{cite book|chapter=Tellurium | title=Mineral Facts and Problems | url=https://books.google.com/books?id=M6RGAQAAIAAJ | page=925 | author = Loebenstein, J. Roger | publisher= U.S. Bureau of Mines | date=1981}}</ref>

The anode sludges contain the [[selenide]]s and tellurides of the [[noble metals]] in compounds with the formula M<sub>2</sub>Se or M<sub>2</sub>Te (M = Cu, Ag, Au). At temperatures of 500&nbsp;°C the anode sludges are roasted with [[sodium carbonate]] under air. The metal ions are reduced to the metals, while the telluride is converted to [[sodium tellurite]].<ref name="wiberg2001" />

{{block indent|M<sub>2</sub>Te + O<sub>2</sub> + Na<sub>2</sub>CO<sub>3</sub> → Na<sub>2</sub>TeO<sub>3</sub> + 2 M + CO<sub>2</sub>}}

[[Tellurite (ion)|Tellurites]] can be leached from the mixture with water and are normally present as hydrotellurites HTeO<sub>3</sub><sup>−</sup> in solution. [[Selenite (ion)|Selenites]] are also formed during this process, but they can be separated by adding [[sulfuric acid]]. The hydrotellurites are converted into the insoluble [[tellurium dioxide]] while the selenites stay in solution.<ref name="wiberg2001" />

{{block indent|{{chem|HTeO|3|-}} + OH<sup>−</sup> + H<sub>2</sub>SO<sub>4</sub> → TeO<sub>2</sub> + {{chem|SO|4|2-}} + 2 H<sub>2</sub>O}}

The metal is produced from the oxide (reduced) either by electrolysis or by reacting the [[tellurium dioxide]] with sulfur dioxide in sulfuric acid.<ref name="wiberg2001" />

{{block indent|TeO<sub>2</sub> + 2 SO<sub>2</sub> + 2H<sub>2</sub>O → Te + 2 {{chem|SO|4|2-}} + 4 H<sup>+</sup>}}

Commercial-grade tellurium is usually marketed as 200-[[Mesh (scale)|mesh]] powder but is also available as slabs, ingots, sticks, or lumps. The year-end price for tellurium in 2000 was [[United States dollar|US$]]30 per kilogram. In recent years, the tellurium price was driven up by increased demand and limited supply, reaching as high as [[United States dollar|US$]]220 per pound in 2006.<ref>{{Cite web|url=http://arizonageology.blogspot.com/2007/05/arizona-tellurium-rush.html|access-date=2009-08-08|date=May 21, 2007|title=An Arizona tellurium rush?|publisher=arizonageology.blogspot.com}}</ref><ref>{{Cite web|url=http://www.resourceinvestor.com/News/2007/4/Pages/Byproducts-Part-I--Is-There-a-Tellurium-Rush-in.aspx|access-date=2009-08-08|date=April 19, 2007|title=Byproducts Part I: Is There a Tellurium Rush in the Making?|publisher=resourceinvestor.com|archive-date=2017-06-25|archive-url=https://web.archive.org/web/20170625134721/http://www.resourceinvestor.com/News/2007/4/Pages/Byproducts-Part-I--Is-There-a-Tellurium-Rush-in.aspx|url-status=dead}}</ref> The average annual price for 99.99%-pure tellurium increased from $38 per kilogram in 2017 to $74 per kilogram in 2018.<ref name=usgs2>Schuyler Anderson, C. (August 2022) [https://pubs.usgs.gov/myb/vol1/2018/myb1-2018-selenium-tellurium.pdf Selenium and Tellurium]. ''2018 Minerals Yearbook''. [[United States Geological Survey]]</ref> Despite the expectation that improved production methods will double production, the [[United States Department of Energy]] (DoE) anticipates a supply shortfall of tellurium by 2025.<ref>{{Cite journal|doi = 10.1016/S0262-4079(11)61452-8|title = 13 elements you can't live without|journal = New Scientist|volume = 210|issue = 2817|page = 39|year = 2011|last1 = Crow|first1 = James Mitchell|bibcode = 2011NewSc.210...36C}}</ref>

In the 2020s, China produced ca. 50% of world's tellurium and was the only country that mined Te as the main target rather than a by-product. This dominance was driven by the rapid expansion of solar cell industry in China. In 2022, the largest Te providers by volume were China (340 tonnes), Russia (80 t), Japan (70 t), Canada (50 t), Uzbekistan (50 t), Sweden (40 t) and the United States (no official data).<ref name=usgs>Flanagan, Daniel M. (2023) [https://pubs.usgs.gov/periodicals/mcs2023/mcs2023-tellurium.pdf Tellurium]. [[United States Geological Survey]]</ref>