Editing Group 7 element (section)

=== Rhenium ===
{{Main article|Rhenium#Production}}

[[Image:Molybdenit 1.jpg|thumb|left|Molybdenite]]
Rhenium is one of the rarest elements in [[Earth's crust]] with an average concentration of 1&nbsp;ppb;<ref name="G&W" /><ref name=":1">{{Cite web|url=https://www.rsc.org/periodic-table/element/75/rhenium|title=Rhenium - Element information, properties and uses {{!}} Periodic Table|website=www.rsc.org|access-date=2019-12-02}}</ref> other sources quote the number of 0.5&nbsp;ppb making it the 77th most abundant element in Earth's crust.{{sfn|Emsley|2001|pp=[https://archive.org/details/naturesbuildingb0000emsl/page/358 358–360]}} Rhenium is probably not found free in nature (its possible natural occurrence is uncertain), but occurs in amounts up to 0.2%<ref name="G&W" /> in the mineral [[molybdenite]] (which is primarily [[molybdenum disulfide]]), the major commercial source, although single molybdenite samples with up to 1.88% have been found.<ref name="Rousch" /> [[Chile]] has the world's largest rhenium reserves, part of the copper ore deposits, and was the leading producer as of 2005.<ref>{{cite web|url=http://minerals.usgs.gov/minerals/pubs/country/2005/cimyb05.pdf |first=Steve T.|last=Anderson| publisher=[[United States Geological Survey]]|title=2005 Minerals Yearbook: Chile|access-date=2008-10-26}}</ref> It was only recently that the first rhenium [[mineral]] was found and described (in 1994), a rhenium [[sulfide mineral]] (ReS<sub>2</sub>) condensing from a [[fumarole]] on [[Kudriavy]] volcano, [[Iturup]] island, in the [[Kuril Islands]].<ref>{{cite journal|last=Korzhinsky|first=M. A.|author2=Tkachenko, S. I. |author3=Shmulovich, K. I. |author4=Taran Y. A. |author5= Steinberg, G. S. | date=2004-05-05|title=Discovery of a pure rhenium mineral at Kudriavy volcano|journal=[[Nature (journal)|Nature]]|volume=369|pages=51–52|doi=10.1038/369051a0|issue=6475|bibcode = 1994Natur.369...51K |s2cid=4344624}}</ref> Kudriavy discharges up to 20–60&nbsp;kg rhenium per year mostly in the form of rhenium disulfide.<ref>{{cite journal| last1 = Kremenetsky| first1 = A. A.| last2 = Chaplygin| first2 = I. V.| title = Concentration of rhenium and other rare metals in gases of the Kudryavy Volcano (Iturup Island, Kurile Islands)| journal = Doklady Earth Sciences| volume = 430| issue = 1| page = 114| date = 2010| doi = 10.1134/S1028334X10010253|bibcode = 2010DokES.430..114K | s2cid = 140632604}}</ref><ref>{{cite journal | last1 = Tessalina | first1 = S. | last2 = Yudovskaya | first2 = M. | last3 = Chaplygin | first3 = I. | last4 = Birck | first4 = J. | last5 = Capmas | first5 = F. | title = Sources of unique rhenium enrichment in fumaroles and sulphides at Kudryavy volcano | journal = Geochimica et Cosmochimica Acta | volume = 72 | page = 889 | date = 2008 | doi = 10.1016/j.gca.2007.11.015 | bibcode=2008GeCoA..72..889T | issue = 3}}</ref> Named [[rheniite]], this rare mineral commands high prices among collectors.<ref>{{cite web|url=http://www.galleries.com/minerals/sulfides/rheniite/rheniite.htm|publisher=Amethyst Galleries|title=The Mineral Rheniite}}</ref> <!--Dr. Kremenetsky from [[Russian Academy of Sciences|RAS]] Mineralogy Institute argues that this source could be commercially exploited,<ref>[http://www.nkj.ru/archive/articles/5340/ Завод на вулкане] // Наука и жизнь, № 11, 2000, in Russian.</ref> but currently there is no active attempts to extract it.-->

[[Image:Ammonium perrhenate.jpg|thumb|right|Ammonium perrhenate]]

Most of the rhenium extracted comes from [[Porphyry (geology)|porphyry]] [[molybdenum]] deposits.<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> These ores typically contain 0.001% to 0.2% rhenium.<ref name="G&W"/> Roasting the ore volatilizes rhenium oxides.<ref name="Rousch">{{cite journal|doi = 10.1021/cr60291a002|title = Recent advances in the chemistry of rhenium|date = 1974|author = Rouschias, George|journal = Chemical Reviews|volume = 74|page = 531|issue = 5}}</ref> [[Rhenium(VII) oxide]] and [[perrhenic acid]] readily dissolve in water; they are leached from flue dusts and gasses and extracted by precipitating with [[potassium chloride|potassium]] or [[ammonium chloride]] as the [[perrhenate]] salts, and purified by [[Recrystallization (chemistry)|recrystallization]].<ref name="G&W" /> Total world production is between 40 and 50 tons/year; the main producers are in Chile, the United States, Peru, and Poland.<ref name="USGS_2012_summary">{{cite web|title=Rhenium|work=Mineral Commodity Summaries |publisher=U.S. Geological Survey|date=January 2012|url=http://minerals.usgs.gov/minerals/pubs/commodity/rhenium/mcs-2012-rheni.pdf|first=Michael J.|last=Magyar|access-date=2013-09-04}}</ref> Recycling of used Pt-Re catalyst and special alloys allow the recovery of another 10 tons per year. Prices for the metal rose rapidly in early 2008, from $1000–$2000 per [[kilogram|kg]] in 2003–2006 to over $10,000 in February 2008.<ref name="minormetals">{{cite web|title=MinorMetal prices|publisher=minormetals.com|url=http://www.minormetals.com/|access-date=2008-02-17|archive-date=2008-05-15|archive-url=https://web.archive.org/web/20080515180506/http://www.minormetals.com/|url-status=dead}}</ref><ref>{{cite web|url=http://in.reuters.com/article/oilRpt/idINL1037587920080710|first=Jan|last=Harvey|title=Analysis: Super hot metal rhenium may reach "platinum prices"|date=2008-07-10|access-date=2008-10-26|publisher=Reuters India|archive-date=2009-01-11|archive-url=https://web.archive.org/web/20090111183605/http://in.reuters.com/article/oilRpt/idINL1037587920080710|url-status=dead}}</ref> The metal form is prepared by reducing [[ammonium perrhenate]] with [[hydrogen]] at high temperatures:<ref name="Brauer" />

:2 NH<sub>4</sub>ReO<sub>4</sub> + 7 H<sub>2</sub> → 2 Re + 8 H<sub>2</sub>O + 2 NH<sub>3</sub>
:There are technologies for the associated extraction of rhenium from productive solutions of underground leaching of uranium ores.<ref>{{Cite journal |last1=Rudenko |first1=A.A. |last2=Troshkina |first2=I.D. |last3=Danileyko |first3=V.V. |last4=Barabanov |first4=O.S. |last5=Vatsura |first5=F.Y. |title=Prospects for selective-and-advanced recovery of rhenium from pregnant solutions of in-situ leaching of uranium ores at Dobrovolnoye deposit |url=https://mst.misis.ru/jour/article/view/287 |journal=Gornye Nauki I Tekhnologii = Mining Science and Technology (Russia) |year=2021 |volume=6 |issue=3 |pages=158–169|doi=10.17073/2500-0632-2021-3-158-169 |s2cid=241476783 |url-access=subscription }}</ref>