\u0164a\u017eba hlin\u00edka z bauxitu je neoddelite\u013enou s\u00fa\u010das\u0165ou vedy a techniky, ktor\u00e1 zabezpe\u010duje stabiln\u00e9 dod\u00e1vky tohto univerz\u00e1lneho kovu. Vzh\u013eadom na jeho \u0161irok\u00e9 vyu\u017eitie sa u\u017e desa\u0165ro\u010dia uskuto\u010d\u0148uje v\u00fdskum \u00fa\u010dinnej\u0161\u00edch sp\u00f4sobov jeho v\u00fdroby.<\/p>\n
Extrakcia zah\u0155\u0148a rozklad hor\u00facim hydroxidom sodn\u00fdm, po ktorom nasleduje vyzr\u00e1\u017eanie hydroxidu hlinit\u00e9ho z roztoku a n\u00e1sledn\u00e9 kalcinovanie na z\u00edskanie komer\u010dne \u010dist\u00e9ho oxidu hlinit\u00e9ho.<\/p>\n
Karl-Josef Bayer vyna\u0161iel Bayerov proces v roku 1887 a dodnes je to z\u00e1kladn\u00e1 priemyseln\u00e1 met\u00f3da v\u00fdroby oxidu hlinit\u00e9ho. Rozdrven\u00fd bauxit sa zmie\u0161a s hydroxidom sodn\u00fdm a vytvor\u00ed sa roztok hlinitanu, ktor\u00fd sl\u00fa\u017ei ako v\u00fdchodiskov\u00fd bod pre \u010fal\u0161ie kroky spracovania.<\/p>\n
Filtr\u00e1ciou sa odstr\u00e1ni vo\u013en\u00e1 voda a ne\u010distoty; filtra\u010dn\u00fd kol\u00e1\u010d sa potom priv\u00e1dza do s\u00e9rie kalcin\u00e1torov, kde sa zahrieva pri vysok\u00fdch teplot\u00e1ch, k\u00fdm sa nevy\u017eenie v\u0161etka vo\u013en\u00e1 voda a chemick\u00e9 ne\u010distoty, \u010d\u00edm sa z\u00edska oxid hlinit\u00fd v pr\u00e1\u0161ku na pou\u017eitie v r\u00f4znych procesoch v\u00fdroby hlin\u00edka, ako je tavenie a odlievanie.<\/p>\n
\u017delezn\u00e1 ruda sa pou\u017e\u00edva na v\u00fdrobu in\u00fdch kovov vr\u00e1tane hor\u010d\u00edka a v\u00e1pnika. V kombin\u00e1cii s in\u00fdmi prvkami m\u00f4\u017ee vytv\u00e1ra\u0165 zliatiny pre \u0161pecifick\u00e9 aplik\u00e1cie, ako s\u00fa leteck\u00e9 motory alebo palivov\u00e9 \u010dl\u00e1nky; okrem toho sl\u00fa\u017ei ako podporn\u00fd materi\u00e1l pri vytv\u00e1ran\u00ed katalyz\u00e1torov pou\u017e\u00edvan\u00fdch na riadenie in\u00fdch chemick\u00fdch reakci\u00ed.<\/p>\n
Hlin\u00edk sa ned\u00e1 vyrobi\u0165 prirodzenou cestou a mus\u00ed sa z\u00edskava\u0165 z rudy r\u00f4znymi technikami rafin\u00e1cie. Dva z\u00e1kladn\u00e9 procesy extrakcie s\u00fa Bayerov a Hall-Heroultov proces, ktor\u00e9 sa za\u010d\u00ednaj\u00fa bauxitom ako v\u00fdchodiskov\u00fdm materi\u00e1lom.<\/p>\n
Bauxit je prirodzene sa vyskytuj\u00faca hrubozrnn\u00e1 hornina obsahuj\u00faca zna\u010dn\u00e9 mno\u017estvo oxidu hlinit\u00e9ho (Al2O3). Hlin\u00edk tvor\u00ed v\u00e4\u010d\u0161inu jeho komer\u010dnej hodnoty; \u0165a\u017eba hlin\u00edka si vy\u017eaduje rozsiahlu spotrebu energie a drah\u00e9 zariadenia; priemysel preto investoval ve\u013ek\u00e9 prostriedky do technol\u00f3gie rafin\u00e1cie bauxitu, aby pokryl 30% celkovej svetovej produkcie.<\/p>\n
Hlin\u00edk je nevyhnutn\u00fd v mnoh\u00fdch priemyseln\u00fdch odvetviach a aplik\u00e1ci\u00e1ch, ale aby bol pou\u017eite\u013en\u00fd, mus\u00ed sa najprv z\u00edska\u0165 z pr\u00edrodn\u00e9ho stavu. Len na nieko\u013ek\u00fdch miestach na Zemi sa nach\u00e1dza jeho element\u00e1rna forma v pr\u00edrode - predov\u0161etk\u00fdm v bauxite - tak\u017ee pred v\u00fdrobou hotov\u00fdch hlin\u00edkov\u00fdch v\u00fdrobkov, ktor\u00e9 sa pou\u017e\u00edvaj\u00fa v mnoh\u00fdch aplik\u00e1ci\u00e1ch, mus\u00ed prebehn\u00fa\u0165 nieko\u013eko procesov rafin\u00e1cie. V\u00fdrobcovia hlin\u00edka sa pri premene surov\u00edn na cenn\u00e9 komodity vo ve\u013ekej miere spoliehaj\u00fa na elektrochemick\u00e9 procesy, ako je Hall-Heroult; pochopenie t\u00fdchto k\u013e\u00fa\u010dov\u00fdch chemick\u00fdch reakci\u00ed umo\u017e\u0148uje nahliadnu\u0165 do tohto d\u00f4le\u017eit\u00e9ho odvetvia.<\/p>\n
Hallov-Heroultov proces spo\u010d\u00edva v elektrochemickom rozp\u00fa\u0161\u0165an\u00ed oxidu hlinit\u00e9ho s cie\u013eom z\u00edska\u0165 \u010dist\u00fd kovov\u00fd hlin\u00edk a plynn\u00fd kysl\u00edk. Ke\u010f\u017ee ide o mimoriadne zlo\u017eit\u00fd proces, ktor\u00fd si na efekt\u00edvnu v\u00fdrobu vy\u017eaduje presn\u00e9 riadenie, teplota, pr\u00fad a zlo\u017eenie elektrolytu musia by\u0165 pr\u00edsne riaden\u00e9, aby sa dosiahli \u00faspe\u0161n\u00e9 v\u00fdsledky.<\/p>\n
Charles Martin Hall, vtedy 20-ro\u010dn\u00fd \u0161tudent prv\u00e9ho ro\u010dn\u00edka na Oberlin College v Ohiu, za\u010dal v roku 1880 sk\u00fama\u0165 sp\u00f4soby v\u00fdroby hlin\u00edka. Hoci jeho prv\u00e9 pokusy s pou\u017eit\u00edm elektrick\u00e9ho pr\u00fadu na z\u00edskanie hlin\u00edka z oxidu hlinit\u00e9ho zlyhali, v roku 1886 sa Hallovi podaril prielom, ktor\u00fd nav\u017edy zmenil hist\u00f3riu hlin\u00edka.<\/p>\n
Rozpustil oxid hlinit\u00fd v kryolitovom miner\u00e1li a do roztoku umiestnil grafitov\u00e9 ty\u010dov\u00e9 elektr\u00f3dy. Potom cez elektr\u00f3dy pustil elektrick\u00fd pr\u00fad, aby sa na kladnej strane (kat\u00f3de) vytvoril roztaven\u00fd hlin\u00edk, zatia\u013e \u010do na z\u00e1pornej strane (an\u00f3de) sa vytv\u00e1ral plynn\u00fd kysl\u00edk. Hall tento proces \u00faspe\u0161ne zopakoval a nakoniec v roku 1888 zalo\u017eil spolo\u010dnos\u0165 Pittsburgh Reduction Company.<\/p>\n
Hall-Heroultov proces sa u\u017e dlho pou\u017e\u00edva ako hlavn\u00e1 priemyseln\u00e1 met\u00f3da v\u00fdroby hlin\u00edka. Hoci je energeticky n\u00e1ro\u010dn\u00fd, za posledn\u00fdch 110 rokov sa pri \u0148om dosiahli v\u00fdznamn\u00e9 pokroky, aby sa zn\u00ed\u017eila spotreba elektrickej energie po\u010das procesu a produkcia oxidu uhli\u010dit\u00e9ho, ktor\u00fd zasa predstavuje ur\u010dit\u00e9 obavy ako sklen\u00edkov\u00fd plyn. Napriek tomu sa po\u010das tohto obdobia vyv\u00edjalo neust\u00e1le \u00fasilie o jeho \u010do najv\u00e4\u010d\u0161ie zn\u00ed\u017eenie.<\/p>\n
Po bauxite, pr\u00edrodnom miner\u00e1li bohatom na hlin\u00edk, je \u010doraz v\u00e4\u010d\u0161\u00ed dopyt a m\u00e1 \u0161irok\u00e9 priemyseln\u00e9 vyu\u017eitie, \u010do podporuje neust\u00e1le zdokona\u013eovanie procesu, ktor\u00fd sa pou\u017e\u00edva na premenu tohto hojn\u00e9ho prvku na \u010dist\u00fd hlin\u00edk. Tento zlo\u017eit\u00fd a energeticky n\u00e1ro\u010dn\u00fd postup z\u00e1vis\u00ed od viacer\u00fdch faktorov vr\u00e1tane umiestnenia z\u00e1sob, bl\u00edzkosti zdrojov energie pre taviace oper\u00e1cie, opatren\u00ed na zv\u00fd\u0161enie \u00fa\u010dinnosti a z\u00e1v\u00e4zku k udr\u017eate\u013en\u00fdm postupom.<\/p>\n
Bayerov proces zah\u0155\u0148a viacero krokov: rozklad s kaustickou sodou, separ\u00e1ciu miner\u00e1lov obsahuj\u00facich hlin\u00edk z roztoku (tzv. \u010derven\u00e9 bahno), zr\u00e1\u017eanie kry\u0161t\u00e1lov hlinitanu sodn\u00e9ho a nakoniec kalcin\u00e1ciu. V\u00fdsledkom je z\u00e1kladn\u00e1 zlo\u017eka v\u00fdroby hlin\u00edka: Hlin\u00edk je tie\u017e nepostr\u00e1date\u013enou surovinou pou\u017e\u00edvanou pri v\u00fdrobe liatych \u017eiaruvzdorn\u00fdch materi\u00e1lov a brus\u00edv.<\/p>\n
Po Bayerovom procese sa oxid hlinit\u00fd m\u00f4\u017ee premeni\u0165 na \u010dist\u00fd hlin\u00edk pomocou Hall-Heroultovho elektrolytick\u00e9ho procesu. Tento proces prebieha v hrnci s uhl\u00edkovou v\u00fdstelkou vybavenom kryolitov\u00fdm k\u00fape\u013eom, ktor\u00fd zni\u017euje teplotu tavenia oxidu hlinit\u00e9ho; t\u00fdmto k\u00fape\u013eom prech\u00e1dza elektrick\u00fd pr\u00fad, zatia\u013e \u010do kysl\u00edk zo vzduchu interaguje s kat\u00f3dov\u00fdmi elektr\u00f3dami za vzniku plynn\u00e9ho oxidu uhli\u010dit\u00e9ho a kvapaln\u00e9ho hlin\u00edka na an\u00f3dov\u00fdch elektr\u00f3dach; plynn\u00fd oxid uhli\u010dit\u00fd sa potom m\u00f4\u017ee zhroma\u017e\u010fova\u0165 na an\u00f3dov\u00fdch elektr\u00f3dach ako plynn\u00fd oxid uhli\u010dit\u00fd, \u010d\u00edm vznik\u00e1 plynn\u00fd oxid uhli\u010dit\u00fd, ktor\u00fd potom na an\u00f3dach vytv\u00e1ra kvapaln\u00fd hlin\u00edk na pou\u017eitie kone\u010dn\u00fdmi pou\u017e\u00edvate\u013emi; viac inform\u00e1ci\u00ed.<\/p>\n
Sch\u00e9my pon\u00fakaj\u00fa poh\u013ead na elektrochemick\u00e9 reakcie, ktor\u00e9 tvoria Hallov-Heroultov proces. Rovnica pre extrakciu oxidu hlinit\u00e9ho n\u00e1m umo\u017e\u0148uje pozorova\u0165, \u017ee jeho hlavn\u00e9 procesy zah\u0155\u0148aj\u00fa:<\/p>\n
L\u00fahovanie kyselinou chlorovod\u00edkovou je po\u010diato\u010dn\u00fdm krokom pri extrakcii bauxitu. Pri jej ide\u00e1lnych koncentr\u00e1ci\u00e1ch a pomere objemu a hmotnosti\/reak\u010dn\u00fdch teplot\u00e1ch dosahuje l\u00fahovanie maxim\u00e1lnu r\u00fdchlos\u0165.<\/p>\n
Oxid hlinit\u00fd, ktor\u00fd sa pre\u010derp\u00e1va do zr\u00e1\u017eac\u00edch n\u00e1dr\u017e\u00ed, sa potom usadzuje a usadzuje, \u010d\u00edm vznik\u00e1 pevn\u00fd hydroxid hlinit\u00fd, a potom sa pren\u00e1\u0161a alebo pre\u010derp\u00e1va priamo do taviacej komory, kde sa zahrieva, a\u017e k\u00fdm sa z neho neroztav\u00ed kovov\u00fd hlin\u00edk, ktor\u00fd sa potom leje do ingotov, ktor\u00e9 sa potom m\u00f4\u017eu kova\u0165, valcova\u0165, \u0165aha\u0165 do r\u00f4znych tvarov alebo ve\u013ekost\u00ed na konkr\u00e9tne pou\u017eitie.<\/p>\n
Hlin\u00edk sa m\u00f4\u017ee pou\u017e\u00edva\u0165 v r\u00f4znych hotov\u00fdch v\u00fdrobkoch, od automobilov a\u017e po lietadl\u00e1. Hlin\u00edkov\u00e9 zliatiny maj\u00fa tie\u017e \u0161pecifick\u00e9 vlastnosti na \u0161pecifick\u00e9 pou\u017eitie vr\u00e1tane pevnosti, odolnosti vo\u010di kor\u00f3zii a vodivosti - tieto zliatiny sa potom m\u00f4\u017eu tavi\u0165, odlieva\u0165 alebo \u0165aha\u0165 do plechov na v\u00fdrobu s\u00fa\u010diastok pre modern\u00e9 stroje, stavebn\u00e9 materi\u00e1ly alebo spotrebn\u00fd tovar.<\/p>\n
Hlin\u00edk je jedn\u00fdm z troch najroz\u0161\u00edrenej\u0161\u00edch prvkov v zemskej k\u00f4re, ale v pr\u00edrode sa nevyskytuje v \u010distej forme. Namiesto toho sa hlin\u00edk mus\u00ed z\u00edskava\u0165 pomocou pokro\u010dil\u00fdch elektrochemick\u00fdch procesov z prim\u00e1rnej suroviny bauxitu, aby sa mohol komer\u010dne vyr\u00e1ba\u0165. Hlin\u00edk zohr\u00e1va neoddelite\u013en\u00fa \u00falohu v mnoh\u00fdch priemyseln\u00fdch aplik\u00e1ci\u00e1ch na celom svete.<\/p>\n
Hall-Heroultov proces je neoddelite\u013en\u00fdm krokom pri z\u00edskavan\u00ed hlin\u00edka. T\u00e1to met\u00f3da zah\u0155\u0148a pou\u017eitie elektrick\u00e9ho pr\u00fadu na spustenie chemick\u00fdch reakci\u00ed, ktor\u00e9 odde\u013euj\u00fa oxid hlinit\u00fd od oxidu hlinit\u00e9ho. \u0160tudenti by si mali pre\u0161tudova\u0165, ako t\u00e1to met\u00f3da funguje, preto\u017ee poskytuje preh\u013ead o jej chemickom zlo\u017een\u00ed aj o technick\u00fdch probl\u00e9moch, ktor\u00e9 s\u00fa s \u0148ou spojen\u00e9.<\/p>\n
Podobne ako pri Bayerovej met\u00f3de sa tento proces za\u010d\u00edna bauxitom ako surovinou, ktor\u00e1 je bohat\u00e1 na oxid hlinit\u00fd a mus\u00ed sa rafinova\u0165 na \u010dist\u00fd kov. Hoci ide o intenz\u00edvny proces n\u00e1ro\u010dn\u00fd na zdroje, umo\u017enil priemyslu na celom svete vyu\u017e\u00edva\u0165 hlin\u00edk.<\/p>\n
Na za\u010diatku procesu sa bauxit mus\u00ed najprv rozdrvi\u0165 a vy\u010disti\u0165, aby sa z\u00edskal oxid hlinit\u00fd (Al2O3), a potom sa zmie\u0161a s kryolitom (Na3AlF6), aby sa zn\u00ed\u017eila jeho teplota topenia a zv\u00fd\u0161ila vodivos\u0165. Po zmie\u0161an\u00ed sa t\u00e1to zmes umiestni do uhl\u00edkovej alebo grafitovej n\u00e1doby ako elektrolytick\u00fd \u010dl\u00e1nok a pou\u017eije sa elektrick\u00fd pr\u00fad; na kat\u00f3de sa vytvor\u00ed kysl\u00edk, zatia\u013e \u010do na an\u00f3de sa oxid hlinit\u00fd zredukuje na tekut\u00fd hlin\u00edk.<\/p>\n
Filtr\u00e1cia a odstre\u010fovanie sa pou\u017e\u00edvaj\u00fa na oddelenie oxidu hlinit\u00e9ho od jeho roztoku a jeho pre\u010derpanie do nieko\u013ek\u00fdch \u0161es\u0165poschodov\u00fdch zr\u00e1\u017eac\u00edch n\u00e1dr\u017e\u00ed, kde sa prid\u00e1vaj\u00fa pevn\u00e9 kry\u0161t\u00e1ly hydr\u00e1tu oxidu hlinit\u00e9ho ako pevn\u00e9 kry\u0161t\u00e1ly na zr\u00e1\u017eanie. Po umiestnen\u00ed do t\u00fdchto n\u00e1dr\u017e\u00ed sa riedi vodou, a\u017e k\u00fdm ned\u00f4jde ku koncentr\u00e1cii na zr\u00e1\u017eanie - potom sa rozmie\u0161a vo vode, aby sa odstr\u00e1nili ne\u010distoty, pred zahriat\u00edm na pribli\u017ene 1 200 stup\u0148ov C na jeho reakciu; po dokon\u010den\u00ed sa op\u00e4\u0165 filtruje pred rozmie\u0161an\u00edm s parou na ka\u0161u oxidu hlinit\u00e9ho na 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\/sk\/wp-json\/wp\/v2\/posts\/748","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/artehistoria.net\/sk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/artehistoria.net\/sk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/artehistoria.net\/sk\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/artehistoria.net\/sk\/wp-json\/wp\/v2\/comments?post=748"}],"version-history":[{"count":1,"href":"https:\/\/artehistoria.net\/sk\/wp-json\/wp\/v2\/posts\/748\/revisions"}],"predecessor-version":[{"id":749,"href":"https:\/\/artehistoria.net\/sk\/wp-json\/wp\/v2\/posts\/748\/revisions\/749"}],"wp:attachment":[{"href":"https:\/\/artehistoria.net\/sk\/wp-json\/wp\/v2\/media?parent=748"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/artehistoria.net\/sk\/wp-json\/wp\/v2\/categories?post=748"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/artehistoria.net\/sk\/wp-json\/wp\/v2\/tags?post=748"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}