T\u011b\u017eba hlin\u00edku z bauxitu je ned\u00edlnou sou\u010d\u00e1st\u00ed v\u011bdeck\u00e9 a technick\u00e9 \u010dinnosti, kter\u00e1 zaji\u0161\u0165uje st\u00e1l\u00e9 dod\u00e1vky tohoto univerz\u00e1ln\u00edho kovu. Vzhledem k jeho \u0161irok\u00e9mu vyu\u017eit\u00ed prob\u00edh\u00e1 v\u00fdzkum \u00fa\u010dinn\u011bj\u0161\u00edch zp\u016fsob\u016f jeho v\u00fdroby ji\u017e n\u011bkolik desetilet\u00ed.<\/p>\n
Extrakce zahrnuje rozklad hork\u00fdm hydroxidem sodn\u00fdm, n\u00e1sledn\u00e9 vysr\u00e1\u017een\u00ed hydroxidu hlinit\u00e9ho z roztoku a n\u00e1sledn\u00e9 kalcinace za \u00fa\u010delem z\u00edsk\u00e1n\u00ed komer\u010dn\u011b \u010dist\u00e9ho oxidu hlinit\u00e9ho.<\/p>\n
Karl-Josef Bayer vynalezl Bayer\u016fv proces v roce 1887 a dodnes je hlavn\u00ed pr\u016fmyslovou metodou v\u00fdroby oxidu hlinit\u00e9ho. Rozdrcen\u00fd bauxit se sm\u00eds\u00ed s hydroxidem sodn\u00fdm a vytvo\u0159\u00ed se roztok hlinitanu, kter\u00fd slou\u017e\u00ed jako v\u00fdchoz\u00ed bod pro dal\u0161\u00ed kroky zpracov\u00e1n\u00ed.<\/p>\n
Filtrac\u00ed se odstran\u00ed voln\u00e1 voda a ne\u010distoty; filtra\u010dn\u00ed kol\u00e1\u010d se pak p\u0159iv\u00e1d\u00ed do \u0159ady kalcin\u00e1tor\u016f, kde se zah\u0159\u00edv\u00e1 p\u0159i vysok\u00fdch teplot\u00e1ch, dokud se nevypud\u00ed ve\u0161ker\u00e1 voln\u00e1 voda a chemick\u00e9 ne\u010distoty, \u010d\u00edm\u017e vznik\u00e1 pr\u00e1\u0161kov\u00fd oxid hlinit\u00fd pro pou\u017eit\u00ed v r\u016fzn\u00fdch procesech zpracov\u00e1n\u00ed hlin\u00edku, jako je taven\u00ed a lit\u00ed.<\/p>\n
\u017delezn\u00e1 ruda se pou\u017e\u00edv\u00e1 k v\u00fdrob\u011b dal\u0161\u00edch kov\u016f, v\u010detn\u011b ho\u0159\u010d\u00edku a v\u00e1pn\u00edku. V kombinaci s jin\u00fdmi prvky m\u016f\u017ee vytv\u00e1\u0159et slitiny pro specifick\u00e9 aplikace, jako jsou leteck\u00e9 motory nebo palivov\u00e9 \u010dl\u00e1nky; krom\u011b toho slou\u017e\u00ed jako podp\u016frn\u00fd materi\u00e1l p\u0159i vytv\u00e1\u0159en\u00ed katalyz\u00e1tor\u016f pou\u017e\u00edvan\u00fdch k \u0159\u00edzen\u00ed jin\u00fdch chemick\u00fdch reakc\u00ed.<\/p>\n
Hlin\u00edk nelze vyrobit p\u0159irozenou cestou a mus\u00ed se z\u00edsk\u00e1vat z rudy r\u016fzn\u00fdmi rafina\u010dn\u00edmi technikami. Dv\u011bma z\u00e1kladn\u00edmi extrak\u010dn\u00edmi procesy jsou Bayer\u016fv a Hall-Heroult\u016fv proces, kter\u00e9 oba za\u010d\u00ednaj\u00ed bauxitem jako v\u00fdchoz\u00edm materi\u00e1lem.<\/p>\n
Bauxit je p\u0159irozen\u011b se vyskytuj\u00edc\u00ed hrubozrnn\u00e1 hornina obsahuj\u00edc\u00ed zna\u010dn\u00e9 mno\u017estv\u00ed oxidu hlinit\u00e9ho (Al2O3). Velkou \u010d\u00e1st jeho komer\u010dn\u00ed hodnoty tvo\u0159\u00ed oxid hlinit\u00fd; z\u00edsk\u00e1v\u00e1n\u00ed hlin\u00edku vy\u017eaduje rozs\u00e1hlou spot\u0159ebu energie a n\u00e1kladn\u00e9 vybaven\u00ed; pr\u016fmysl proto investoval velk\u00e9 prost\u0159edky do technologie rafinace bauxitu, aby pokryl 30% celkov\u00e9 sv\u011btov\u00e9 produkce.<\/p>\n
Hlin\u00edk je nezbytn\u00fd v mnoha pr\u016fmyslov\u00fdch odv\u011btv\u00edch a aplikac\u00edch, ale aby byl pou\u017eiteln\u00fd, mus\u00ed b\u00fdt nejprve z\u00edsk\u00e1n z p\u0159\u00edrodn\u00edho stavu. Pouze na n\u011bkolika m\u00edstech na Zemi se nach\u00e1z\u00ed jeho p\u0159\u00edrodn\u00ed forma - p\u0159edev\u0161\u00edm v bauxitu -, tak\u017ee p\u0159ed v\u00fdrobou hotov\u00fdch hlin\u00edkov\u00fdch v\u00fdrobk\u016f, kter\u00e9 se pou\u017e\u00edvaj\u00ed v mnoha aplikac\u00edch, mus\u00ed prob\u011bhnout n\u011bkolik rafina\u010dn\u00edch proces\u016f. V\u00fdrobci hlin\u00edku se p\u0159i p\u0159em\u011bn\u011b surovin na cenn\u00e9 komodity do zna\u010dn\u00e9 m\u00edry spol\u00e9haj\u00ed na elektrochemick\u00e9 procesy, jako je Hall-Heroult\u016fv proces; pochopen\u00ed t\u011bchto kl\u00ed\u010dov\u00fdch chemick\u00fdch reakc\u00ed umo\u017e\u0148uje nahl\u00e9dnout do tohoto d\u016fle\u017eit\u00e9ho odv\u011btv\u00ed.<\/p>\n
Hall-Heroult\u016fv proces je zalo\u017een na elektrochemick\u00e9m rozpou\u0161t\u011bn\u00ed oxidu hlinit\u00e9ho za vzniku \u010dist\u00e9ho kovov\u00e9ho hlin\u00edku a plynn\u00e9ho kysl\u00edku. Jeliko\u017e se jedn\u00e1 o mimo\u0159\u00e1dn\u011b slo\u017eit\u00fd proces, kter\u00fd pro efektivn\u00ed v\u00fdrobu vy\u017eaduje p\u0159esn\u00e9 \u0159\u00edzen\u00ed, mus\u00ed b\u00fdt pro dosa\u017een\u00ed \u00fasp\u011b\u0161n\u00fdch v\u00fdsledk\u016f p\u0159\u00edsn\u011b \u0159\u00edzena teplota, proud a slo\u017een\u00ed elektrolytu.<\/p>\n
Charles Martin Hall, tehdy dvacetilet\u00fd student prvn\u00edho ro\u010dn\u00edku Oberlin College v Ohiu, za\u010dal v roce 1880 zkoumat zp\u016fsoby v\u00fdroby hlin\u00edku. P\u0159esto\u017ee jeho prvn\u00ed pokusy o z\u00edsk\u00e1n\u00ed hlin\u00edku z oxidu hlinit\u00e9ho pomoc\u00ed elektrick\u00e9ho proudu selhaly, v roce 1886 Hall u\u010dinil pr\u016flom, kter\u00fd nav\u017edy zm\u011bnil historii hlin\u00edku.<\/p>\n
Rozpustil oxid hlinit\u00fd v kryolitov\u00e9m miner\u00e1lu a do roztoku um\u00edstil grafitov\u00e9 ty\u010dov\u00e9 elektrody. Pot\u00e9 elektrodami prot\u00e9kal elektrick\u00fd proud, \u010d\u00edm\u017e se na kladn\u00e9 stran\u011b (katod\u011b) vytv\u00e1\u0159el roztaven\u00fd hlin\u00edk, zat\u00edmco na z\u00e1porn\u00e9 stran\u011b (anod\u011b) doch\u00e1zelo k produkci plynn\u00e9ho kysl\u00edku.Hall tento proces \u00fasp\u011b\u0161n\u011b opakoval a nakonec v roce 1888 zalo\u017eil Pittsburgh Reduction Company.<\/p>\n
Hall-Heroult\u016fv proces se ji\u017e dlouho pou\u017e\u00edv\u00e1 jako hlavn\u00ed pr\u016fmyslov\u00e1 metoda v\u00fdroby hlin\u00edku. A\u010dkoli je energeticky n\u00e1ro\u010dn\u00fd, za posledn\u00edch 110 let se poda\u0159ilo dos\u00e1hnout v\u00fdznamn\u00fdch pokrok\u016f ve sni\u017eov\u00e1n\u00ed spot\u0159eby elektrick\u00e9 energie b\u011bhem procesu a produkce oxidu uhli\u010dit\u00e9ho, kter\u00fd zase p\u0159edstavuje ur\u010dit\u00fd probl\u00e9m jako sklen\u00edkov\u00fd plyn. P\u0159esto se v tomto \u010dasov\u00e9m horizontu vyv\u00edjelo neust\u00e1l\u00e9 \u00fasil\u00ed o jeho co nejv\u011bt\u0161\u00ed sn\u00ed\u017een\u00ed.<\/p>\n
Bauxit, p\u0159\u00edrodn\u00ed miner\u00e1l bohat\u00fd na hlin\u00edk, m\u00e1 st\u00e1le rostouc\u00ed popt\u00e1vku a \u0161irok\u00e9 pr\u016fmyslov\u00e9 vyu\u017eit\u00ed, co\u017e podporuje neust\u00e1l\u00e9 zdokonalov\u00e1n\u00ed procesu p\u0159em\u011bny tohoto hojn\u00e9ho prvku na \u010di\u0161t\u011bn\u00fd hlin\u00edk. Tento slo\u017eit\u00fd a energeticky n\u00e1ro\u010dn\u00fd postup z\u00e1vis\u00ed na mnoha faktorech, v\u010detn\u011b um\u00edst\u011bn\u00ed z\u00e1sob, bl\u00edzkosti zdroj\u016f energie pro tavic\u00ed operace, opat\u0159en\u00ed na zv\u00fd\u0161en\u00ed \u00fa\u010dinnosti a z\u00e1vazku k udr\u017eiteln\u00fdm postup\u016fm.<\/p>\n
Bayer\u016fv proces zahrnuje n\u011bkolik krok\u016f: rozklad pomoc\u00ed kaustick\u00e9 sody, odd\u011blen\u00ed miner\u00e1l\u016f obsahuj\u00edc\u00edch hlin\u00edk z roztoku (tzv. \u010derven\u00e9 bahno), sr\u00e1\u017een\u00ed krystal\u016f hlinitanu sodn\u00e9ho a nakonec kalcinaci. V\u00fdsledkem je z\u00e1kladn\u00ed slo\u017eka v\u00fdroby hlin\u00edku: Hlin\u00edk je tak\u00e9 nepostradatelnou surovinou pou\u017e\u00edvanou p\u0159i v\u00fdrob\u011b lit\u00fdch \u017e\u00e1ruvzdorn\u00fdch materi\u00e1l\u016f a brusiv.<\/p>\n
Po Bayerov\u011b procesu lze oxid hlinit\u00fd p\u0159ev\u00e9st na \u010dist\u00fd hlin\u00edk pomoc\u00ed Hall-Heroultova elektrolytick\u00e9ho procesu. Ten prob\u00edh\u00e1 v n\u00e1dob\u011b s uhl\u00edkovou vlo\u017ekou a kryolitovou l\u00e1zn\u00ed, kter\u00e1 sni\u017euje teplotu t\u00e1n\u00ed oxidu hlinit\u00e9ho; touto l\u00e1zn\u00ed proch\u00e1z\u00ed elektrick\u00fd proud, zat\u00edmco kysl\u00edk ze vzduchu interaguje s katodov\u00fdmi elektrodami za vzniku plynn\u00e9ho oxidu uhli\u010dit\u00e9ho a kapaln\u00e9ho hlin\u00edku na anodov\u00fdch elektrod\u00e1ch; plynn\u00fd oxid uhli\u010dit\u00fd lze pak shroma\u017e\u010fovat na anodov\u00fdch elektrod\u00e1ch jako plynn\u00fd oxid uhli\u010dit\u00fd, \u010d\u00edm\u017e vznik\u00e1 plynn\u00fd oxid uhli\u010dit\u00fd, kter\u00fd pak na anod\u00e1ch tvo\u0159\u00ed kapaln\u00fd hlin\u00edk pro pou\u017eit\u00ed kone\u010dn\u00fdmi u\u017eivateli; v\u00edce informac\u00ed.<\/p>\n
Sch\u00e9mata nab\u00edzej\u00ed pohled na elektrochemick\u00e9 reakce, kter\u00e9 tvo\u0159\u00ed Hall\u016fv-Heroult\u016fv proces. Rovnice pro extrakci oxidu hlinit\u00e9ho n\u00e1m umo\u017e\u0148uje pozorovat, \u017ee jeho hlavn\u00ed procesy zahrnuj\u00ed:<\/p>\n
Prvn\u00edm krokem p\u0159i extrakci bauxitu je lou\u017een\u00ed kyselinou chlorovod\u00edkovou. P\u0159i jej\u00edch ide\u00e1ln\u00edch koncentrac\u00edch a pom\u011bru objemu a hmotnosti\/reak\u010dn\u00edch teplot\u00e1ch dosahuje vyluhov\u00e1n\u00ed nejvy\u0161\u0161\u00ed rychlosti.<\/p>\n
Po p\u0159e\u010derp\u00e1n\u00ed do sr\u00e1\u017eec\u00edch n\u00e1dr\u017e\u00ed se oxid hlinit\u00fd usad\u00ed a vyseje, \u010d\u00edm\u017e vznikne pevn\u00fd hydroxid hlinit\u00fd, a pot\u00e9 se p\u0159enese nebo p\u0159e\u010derp\u00e1 p\u0159\u00edmo do tavic\u00ed komory, kde se zah\u0159\u00edv\u00e1, dokud se z n\u011bj neroztav\u00ed kovov\u00fd hlin\u00edk, kter\u00fd se pak nalije do ingot\u016f, kter\u00e9 se pak mohou kovat, v\u00e1lcovat, ta\u017eit do r\u016fzn\u00fdch tvar\u016f nebo velikost\u00ed pro konkr\u00e9tn\u00ed pou\u017eit\u00ed.<\/p>\n
Hlin\u00edk lze pou\u017e\u00edt v \u0159ad\u011b hotov\u00fdch v\u00fdrobk\u016f, od automobil\u016f po letadla. Slitiny hlin\u00edku maj\u00ed tak\u00e9 specifick\u00e9 vlastnosti pro konkr\u00e9tn\u00ed pou\u017eit\u00ed, v\u010detn\u011b pevnosti, odolnosti proti korozi a vodivosti - tyto slitiny lze n\u00e1sledn\u011b roztavit, odl\u00edt nebo vyt\u00e1hnout do plech\u016f a vyrobit z nich sou\u010d\u00e1sti pro modern\u00ed stroje, stavebn\u00ed materi\u00e1ly nebo spot\u0159ebn\u00ed zbo\u017e\u00ed.<\/p>\n
Hlin\u00edk je jedn\u00edm ze t\u0159\u00ed nejroz\u0161\u00ed\u0159en\u011bj\u0161\u00edch prvk\u016f v zemsk\u00e9 k\u016f\u0159e, ale v p\u0159\u00edrod\u011b se nevyskytuje v \u010dist\u00e9 form\u011b. M\u00edsto toho mus\u00ed b\u00fdt hlin\u00edk z\u00edsk\u00e1v\u00e1n pomoc\u00ed pokro\u010dil\u00fdch elektrochemick\u00fdch proces\u016f z prim\u00e1rn\u00ed suroviny bauxitu, aby mohl b\u00fdt komer\u010dn\u011b vyr\u00e1b\u011bn. Hlin\u00edk hraje ned\u00edlnou roli v mnoha pr\u016fmyslov\u00fdch aplikac\u00edch po cel\u00e9m sv\u011bt\u011b.<\/p>\n
Hall-Heroult\u016fv proces je ned\u00edlnou sou\u010d\u00e1st\u00ed procesu z\u00edsk\u00e1v\u00e1n\u00ed hlin\u00edku. Tato metoda zahrnuje pou\u017eit\u00ed elektrick\u00e9ho proudu k zah\u00e1jen\u00ed chemick\u00fdch reakc\u00ed, kter\u00e9 odd\u011bluj\u00ed oxid hlinit\u00fd od oxidu hlinit\u00e9ho. Studenti by si m\u011bli prostudovat, jak tato metoda funguje, proto\u017ee poskytuje vhled jak do jej\u00ed chemie, tak do souvisej\u00edc\u00edch technick\u00fdch probl\u00e9m\u016f.<\/p>\n
Stejn\u011b jako u Bayerovy metody se i tento proces za\u010d\u00edn\u00e1 bauxitem jako surovinou, kter\u00e1 je bohat\u00e1 na oxid hlinit\u00fd a kterou je t\u0159eba rafinovat na \u010dist\u00fd kov. A\u010dkoli se jedn\u00e1 o n\u00e1ro\u010dn\u00fd proces, kter\u00fd vy\u017eaduje velk\u00e9 mno\u017estv\u00ed zdroj\u016f, umo\u017enil pr\u016fmyslu po cel\u00e9m sv\u011bt\u011b vyu\u017e\u00edvat hlin\u00edk.<\/p>\n
Na za\u010d\u00e1tku procesu se bauxit mus\u00ed nejprve rozdrtit a vy\u010distit, aby se z\u00edskal oxid hlinit\u00fd (Al2O3), a pot\u00e9 sm\u00edchat s kryolitem (Na3AlF6), aby se sn\u00ed\u017eil jeho bod t\u00e1n\u00ed a zv\u00fd\u0161ila vodivost. Po sm\u00edch\u00e1n\u00ed se tato sm\u011bs vlo\u017e\u00ed do uhl\u00edkov\u00e9ho nebo grafitov\u00e9ho hrnce jako elektrolytick\u00fd \u010dl\u00e1nek a p\u0159ivede se elekt\u0159ina; na katod\u011b se vytvo\u0159\u00ed kysl\u00edk, zat\u00edmco na anod\u011b se oxid hlinit\u00fd redukuje na tekut\u00fd hlin\u00edk.<\/p>\n
Filtrac\u00ed a odst\u0159e\u010fov\u00e1n\u00edm se odd\u011bl\u00ed oxid hlinit\u00fd od roztoku a p\u0159e\u010derp\u00e1 se do n\u011bkolika \u0161estipatrov\u00fdch sr\u00e1\u017eec\u00edch n\u00e1dr\u017e\u00ed, kde se p\u0159id\u00e1vaj\u00ed pevn\u00e9 krystaly hydr\u00e1tu oxidu hlinit\u00e9ho jako pevn\u00e9 krystaly pro sr\u00e1\u017een\u00ed. Jakmile je v t\u011bchto n\u00e1dr\u017e\u00edch, \u0159ed\u00ed se vodou, dokud nem\u016f\u017ee doj\u00edt ke koncentraci pro sr\u00e1\u017een\u00ed - pot\u00e9 se rozm\u011bln\u00ed ve vod\u011b, aby se odstranily ne\u010distoty, a zah\u0159\u00edv\u00e1 se na teplotu p\u0159ibli\u017en\u011b 1 200 stup\u0148\u016f C pro svou reakci; po dokon\u010den\u00ed se op\u011bt filtruje, ne\u017e se rozm\u011bln\u00ed p\u00e1rou na ka\u0161i oxidu hlinit\u00e9ho pro v\u00fdrobu.<\/p>","protected":false},"excerpt":{"rendered":"
Extraction of aluminium from bauxite is an integral aspect of scientific and engineering that ensures a steady supply of this […]<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""}},"footnotes":""},"categories":[3],"tags":[],"class_list":["post-748","post","type-post","status-publish","format-standard","hentry","category-knowledge"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/artehistoria.net\/cs\/wp-json\/wp\/v2\/posts\/748","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/artehistoria.net\/cs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/artehistoria.net\/cs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/artehistoria.net\/cs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/artehistoria.net\/cs\/wp-json\/wp\/v2\/comments?post=748"}],"version-history":[{"count":1,"href":"https:\/\/artehistoria.net\/cs\/wp-json\/wp\/v2\/posts\/748\/revisions"}],"predecessor-version":[{"id":749,"href":"https:\/\/artehistoria.net\/cs\/wp-json\/wp\/v2\/posts\/748\/revisions\/749"}],"wp:attachment":[{"href":"https:\/\/artehistoria.net\/cs\/wp-json\/wp\/v2\/media?parent=748"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/artehistoria.net\/cs\/wp-json\/wp\/v2\/categories?post=748"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/artehistoria.net\/cs\/wp-json\/wp\/v2\/tags?post=748"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}