\u0164a\u017eba hlin\u00edka z bauxitu je jedn\u00fdm z najzlo\u017eitej\u0161\u00edch priemyseln\u00fdch procesov na svete, ktor\u00fd zah\u0155\u0148a obrovsk\u00e9 mno\u017estvo vedeck\u00fdch a technick\u00fdch \u00faloh, ktor\u00e9 zabezpe\u010duj\u00fa nepretr\u017eit\u00e9 dod\u00e1vky tohto z\u00e1kladn\u00e9ho kovu.<\/p>\n
Pri kyslom procese sa pou\u017e\u00edvaj\u00fa kyseliny s\u00edrov\u00e1, chlorovod\u00edkov\u00e1 alebo dusi\u010dn\u00e1 ako rozp\u00fa\u0161\u0165adl\u00e1 na vyl\u00fahovanie ne\u010dist\u00f4t, ako s\u00fa oxidy \u017eeleza a tit\u00e1nu z bauxitu. Vzorky XRD uk\u00e1zali, \u017ee so zvy\u0161uj\u00facou sa koncentr\u00e1ciou alk\u00e1li\u00ed sa zvy\u0161oval aj pomer extrakcie oxidu hlinit\u00e9ho.<\/p>\n
Hlin\u00edk je jedn\u00fdm z najroz\u0161\u00edrenej\u0161\u00edch kovov na Zemi, ale jeho \u010dist\u00e1 forma sa v pr\u00edrode nenach\u00e1dza. Namiesto toho si jeho \u0165a\u017eba vy\u017eaduje mnoho f\u00e1z zah\u0155\u0148aj\u00facich rozklad, \u010distenie, zr\u00e1\u017eanie a kalcin\u00e1ciu, aby sa dosiahol kone\u010dn\u00fd stav v\u00fdrobku - to rob\u00ed z hlin\u00edka jeden z energeticky najn\u00e1ro\u010dnej\u0161\u00edch priemyseln\u00fdch v\u00fdrobkov na svete.<\/p>\n
Digescia je k\u013e\u00fa\u010dov\u00fdm krokom Bayerovho procesu z\u00edskavania hlin\u00edka z bauxitovej rudy. Na jej v\u00fdkon m\u00e1 vplyv mnoho faktorov vr\u00e1tane teploty suspenzie, koncentr\u00e1cie s\u00f3dy kaustickej a pomeru kaustick\u00fdch l\u00e1tok; na optimaliz\u00e1ciu r\u00fdchlosti vyhn\u00edvania by ste mohli zn\u00ed\u017ei\u0165 teplotu, zv\u00fd\u0161i\u0165 pomer kaustick\u00fdch l\u00e1tok alebo pou\u017ei\u0165 vy\u0161\u0161ie koncentr\u00e1cie kaustick\u00fdch l\u00e1tok, ale tieto opatrenia by boli pre rafin\u00e9rie pravdepodobne n\u00e1kladnej\u0161ie a nepohodlnej\u0161ie, ako je potrebn\u00e9.<\/p>\n
V r\u00e1mci procesu rozkladu sa v\u00e4\u010d\u0161ina \u017eeleza v bauxite men\u00ed na nez\u00e1visl\u00fa f\u00e1zu ilmenitu, zatia\u013e \u010do nemagnetick\u00fd materi\u00e1l zost\u00e1va vo forme diaoyudaoitu a hlinitokremi\u010ditanu sodn\u00e9ho. Oddelenie nemagnetick\u00fdch materi\u00e1lov zlep\u0161uje rozklad oxidu hlinit\u00e9ho, av\u0161ak vzh\u013eadom na uzavret\u00e9 miner\u00e1ly pr\u00edtomn\u00e9 v jeho \u0161trukt\u00fare sa diaoyudaoit nemus\u00ed \u013eahko rozklada\u0165 pri ni\u017e\u0161\u00edch teplot\u00e1ch rozkladu.<\/p>\n
Priemern\u00e9 n\u00e1klady na energiu spojen\u00e9 s v\u00fdrobou oxidu hlinit\u00e9ho sa v jednotliv\u00fdch krajin\u00e1ch v\u00fdrazne l\u00ed\u0161ia v d\u00f4sledku faktorov, ako je typ pou\u017eitej technol\u00f3gie, pou\u017eit\u00fd bauxit a procesy rozkladu, ktor\u00e9 sa navz\u00e1jom v\u00fdrazne l\u00ed\u0161ia. Existuj\u00fa v\u0161ak ur\u010dit\u00e9 spolo\u010dn\u00e9 faktory, ktor\u00e9 prispievaj\u00fa k zv\u00fd\u0161enej spotrebe energie, vr\u00e1tane:<\/p>\n
Proces ferment\u00e1cie predstavuje v\u00e4\u010d\u0161inu spotreby energie pri v\u00fdrobe oxidu hlinit\u00e9ho, preto\u017ee si vy\u017eaduje elektrick\u00fa energiu a vodu na ohrievanie a mie\u0161anie kalu a na vyplavovanie \u00edlov\u00fdch ne\u010dist\u00f4t. Na to, aby prebiehala optim\u00e1lna digescia a aby sa zn\u00ed\u017eili energetick\u00e9 straty, musia vedci presk\u00fama\u0165 s\u00fa\u010dasn\u00e9 podmienky jej vyu\u017e\u00edvania. Vedci to m\u00f4\u017eu dosiahnu\u0165 zhroma\u017e\u010fovan\u00edm \u00fadajov a inform\u00e1ci\u00ed z dokumenta\u010dn\u00e9ho centra a rozhovormi s odborn\u00edkmi na v\u00fdrobn\u00fa linku, potom porovnan\u00edm s\u00fa\u010dasn\u00e9ho stavu procesu vyhn\u00edvania s jeho p\u00f4vodn\u00fdm n\u00e1vrhom, aby sa ur\u010dili hlavn\u00e9 odch\u00fdlky.<\/p>\n
Z\u00edskavanie hlin\u00edka m\u00f4\u017ee by\u0165 zlo\u017eit\u00fd a energeticky n\u00e1ro\u010dn\u00fd proces, ktor\u00fd je v\u0161ak nevyhnutn\u00fd pre mnoh\u00e9 komer\u010dn\u00e9 a priemyseln\u00e9 aplik\u00e1cie. Preto je pochopenie tohto zlo\u017eit\u00e9ho postupu na zabezpe\u010denie jeho \u00faspe\u0161nosti mimoriadne d\u00f4le\u017eit\u00e9 - diagramy m\u00f4\u017eu pom\u00f4c\u0165 objasni\u0165 chemick\u00e9 reakcie prebiehaj\u00face po\u010das v\u00fdroby, ktor\u00e9 tvoria tento zlo\u017eit\u00fd postup, a ich v\u00fdznam pre jeho realiz\u00e1ciu.<\/p>\n
Jedn\u00fdm z k\u013e\u00fa\u010dov\u00fdch krokov je rafin\u00e1cia bauxitu na oxid hlinit\u00fd a nakoniec na kovov\u00fd hlin\u00edk, a to bu\u010f elektrol\u00fdzou, alebo Bayerov\u00fdm procesom. Oba postupy zabezpe\u010duj\u00fa spo\u013eahliv\u00e9 dod\u00e1vky kovov\u00e9ho hlin\u00edka prostredn\u00edctvom t\u00fdchto procesov. Oba s\u00fa z\u00e1visl\u00e9 od elektrol\u00fdzy ako v\u00fdrobn\u00e9ho zdroja.<\/p>\n
Bauxitov\u00e1 ruda je bohat\u00fdm zdrojom hlin\u00edka a vy\u017eaduje si zna\u010dn\u00e9 spracovanie, aby sa premenila na roztok bohat\u00fd na oxid hlinit\u00fd pripraven\u00fd na \u010fal\u0161iu f\u00e1zu. Digescia zah\u0155\u0148a drvenie bauxitovej rudy pred jej zmie\u0161an\u00edm s hor\u00facimi koncentrovan\u00fdmi roztokmi hydroxidu sodn\u00e9ho s cie\u013eom rozpusti\u0165 obsah oxidu hlinit\u00e9ho, \u010do vedie k z\u00edskaniu \u010d\u00edreho l\u00fahu. Potom nasleduje \u010d\u00edrenie, pri ktorom sa odde\u013euj\u00fa ne\u010distoty (s\u00fahrnne zn\u00e1me ako \u010derven\u00e9 bahno) pred zr\u00e1\u017ean\u00edm a kalcin\u00e1ciou vy\u010d\u00edrenej kvapaliny.<\/p>\n
Na premenu oxidu hlinit\u00e9ho na \u010dist\u00fd hlin\u00edk je potrebn\u00e9 tavenie elektrol\u00fdzou. Zmes oxidu hlinit\u00e9ho a hydroxidu sodn\u00e9ho sa potom umiestni do kryolitov\u00e9ho roztoku (fluorid hlinito-hlinit\u00fd), pri\u010dom na udr\u017eanie tohto stavu sa mus\u00ed vynalo\u017ei\u0165 mimoriadne ve\u013ea energie; na v\u00fdrobu jednej tony oxidu hlinit\u00e9ho je potrebn\u00fdch 14 000 - 16 000 kilowatthod\u00edn.<\/p>\n
Teplo vznikaj\u00face po\u010das tohto procesu poh\u00e1\u0148a elektrochemick\u00fa reakciu. Pri prechode elektrick\u00e9ho pr\u00fadu syst\u00e9mom sa na an\u00f3de vytv\u00e1ra kysl\u00edk, ktor\u00fd sa sp\u00e1ja s uhl\u00edkom za vzniku plynn\u00e9ho oxidu uhli\u010dit\u00e9ho; zvy\u0161n\u00fd roztaven\u00fd hlin\u00edk sa zhroma\u017e\u010fuje na kat\u00f3de, ktor\u00e1 je vylo\u017een\u00e1 grafitom alebo uhl\u00edkom; pravidelne sa od\u010derp\u00e1va a prepravuje do udr\u017eiavac\u00edch pec\u00ed; po \u010fal\u0161ej rafin\u00e1cii a pridan\u00ed leguj\u00facich prvkov pod\u013ea potreby sa odlieva do ingotov na bud\u00face pou\u017eitie.<\/p>\n
Jedn\u00fdm z k\u013e\u00fa\u010dov\u00fdch krokov pri z\u00edskavan\u00ed oxidu hlinit\u00e9ho je zr\u00e1\u017eanie. Zr\u00e1\u017eacie reakcie maj\u00fa r\u00f4zne formy; na \u00fa\u010dely extrakcie kry\u0161t\u00e1lov hydroxidu hlinit\u00e9ho z odpadov\u00fdch tokov. Karl Bayer pri svojej p\u00f4vodnej v\u00fdvojovej pr\u00e1ci pou\u017eil ako semeno jemnozrnn\u00e9 kry\u0161t\u00e1ly; tento pr\u00edstup zvy\u0161uje v\u00fd\u0165a\u017enos\u0165, ale m\u00f4\u017ee ma\u0165 za n\u00e1sledok vy\u0161\u0161ie koncentr\u00e1cie uhli\u010ditanov a zvy\u0161uje produkciu ne\u010dist\u00f4t, ako je oxid kremi\u010dit\u00fd, ktor\u00fd zni\u017euje mieru v\u00fd\u0165a\u017enosti hlin\u00edka.<\/p>\n
Na rie\u0161enie t\u00fdchto v\u00fdziev sa v s\u00fa\u010dasnosti v r\u00e1mci nieko\u013ek\u00fdch v\u00fdskumn\u00fdch projektov hodnot\u00ed \u00fa\u010dinnos\u0165 r\u00f4znych i\u00f3novo-v\u00fdmenn\u00fdch \u017eiv\u00edc pri zlep\u0161ovan\u00ed \u00fa\u010dinnosti zr\u00e1\u017eania. \u017divice na v\u00fdmenu i\u00f3nov s\u00fa vysokomolekulov\u00e9 polym\u00e9rne materi\u00e1ly obsahuj\u00face v ka\u017edej molekule mno\u017estvo i\u00f3nov\u00fdch funk\u010dn\u00fdch skup\u00edn, ktor\u00e9 zvy\u010dajne zah\u0155\u0148aj\u00fa bu\u010f skupiny kyseliny sulf\u00f3novej, alebo skupiny kyseliny karboxylovej na v\u00fdmenu. Oba typy \u017eiv\u00edc sa m\u00f4\u017eu pou\u017ei\u0165 na extrakciu s\u00f3dy zo \u017eierav\u00fdch roztokov, \u010do vedie k zn\u00ed\u017eeniu celkov\u00e9ho obsahu \u017eieraviny (TC) aj celkov\u00e9ho obsahu alk\u00e1li\u00ed (TA). Okrem toho m\u00f4\u017eu \u017eivice na v\u00fdmenu kati\u00f3nov neutralizova\u0165 sodn\u00e9 i\u00f3ny pr\u00edtomn\u00e9 v pou\u017eitom bayerovom l\u00fahu, \u010do vedie k zv\u00fd\u0161eniu pres\u00fdtenia v porovnan\u00ed s rozpustnos\u0165ou oxidu hlinit\u00e9ho.<\/p>\n
Pri r\u00f4znych podmienkach karboniz\u00e1cie sa zistilo, \u017ee pr\u00edtomnos\u0165 kysl\u00edka m\u00e1 priazniv\u00fd vplyv na r\u00fdchlos\u0165 zr\u00e1\u017eania. Presnej\u0161ie, teplota, pri ktorej sa zr\u00e1\u017eanie za\u010dalo, sa v\u00fdrazne zv\u00fd\u0161ila, zatia\u013e \u010do XRD anal\u00fdza zrazeniny uk\u00e1zala, \u017ee obsahuje dawsonit, ako sa predpokladalo na z\u00e1klade termodynamick\u00fdch v\u00fdpo\u010dtov.<\/p>\n
Zr\u00e1\u017eanie oxidu hlinit\u00e9ho je jednou z najkritickej\u0161\u00edch a naj\u0165a\u017e\u0161\u00edch f\u00e1z v\u00fdroby hlin\u00edka z bauxitu. Zr\u00e1\u017eanie sa mus\u00ed uskuto\u010dni\u0165, aby sa vyrobil hydroxid hlinit\u00fd, ktor\u00fd sa spotrebuje v kalcina\u010dn\u00fdch peciach hlinik\u00e1rn\u00ed; preto filtra\u010dn\u00e9 a separa\u010dn\u00e9 zariadenia pou\u017e\u00edvan\u00e9 v spracovate\u013esk\u00fdch z\u00e1vodoch musia pracova\u0165 za mimoriadne pr\u00edsnych podmienok.<\/p>\n
Filtra\u010dn\u00e9 a odlu\u010dovacie zariadenia v z\u00e1vodoch na v\u00fdrobu oxidu hlinit\u00e9ho musia by\u0165 robustn\u00e9, odoln\u00e9, spo\u013eahliv\u00e9 a s dlhou \u017eivotnos\u0165ou, aby mohli spr\u00e1vne fungova\u0165 v n\u00e1ro\u010dn\u00fdch podmienkach vr\u00e1tane vysok\u00fdch tepl\u00f4t a tlakov a z\u00e1rove\u0148 odstra\u0148ova\u0165 vysoko abraz\u00edvne zvy\u0161ky bauxitu, ktor\u00e9 m\u00f4\u017eu po\u0161kodi\u0165 in\u00e9 zariadenia, ako s\u00fa \u010derpadl\u00e1, mie\u0161a\u010dky a mie\u0161adl\u00e1. V tak\u00fdchto zariadeniach sa preto nach\u00e1dzaj\u00fa niektor\u00e9 z najlep\u0161\u00edch filtra\u010dn\u00fdch a odlu\u010dovac\u00edch zariaden\u00ed na svete.<\/p>\n
Kalcin\u00e1cia je posledn\u00fdm syntetick\u00fdm krokom v procese a m\u00e1 viacero vplyvov na morfol\u00f3giu, f\u00e1zov\u00e9 zlo\u017eenie a chemick\u00e9 zlo\u017eenie oxidu hlinit\u00e9ho. Teplota a trvanie reakcie maj\u00fa zvy\u010dajne najv\u00e4\u010d\u0161\u00ed vplyv; teplota by sa mala nastavi\u0165 v z\u00e1vislosti od po\u017eadovan\u00fdch cie\u013eov morfol\u00f3gie\/zlo\u017eenia, ako aj od v\u00fdrobn\u00fdch alebo in\u00fdch pou\u017eit\u00ed tohto materi\u00e1lu oxidu hlinit\u00e9ho; \u010das potrebn\u00fd na dosiahnutie tohto v\u00fdsledku bude ur\u010dova\u0165 jeho d\u013a\u017eku.<\/p>\n
Najroz\u0161\u00edrenej\u0161ia met\u00f3da kalcin\u00e1cie zah\u0155\u0148a l\u00fahovanie kaol\u00ednov\u00fdch \u00edlov kyselinou chlorovod\u00edkovou pred vyzr\u00e1\u017ean\u00edm kry\u0161t\u00e1lov hexahydr\u00e1tu chloridu hlinit\u00e9ho kyselinou chlorovod\u00edkovou a n\u00e1sledn\u00fdm kalcinovan\u00edm pri vysokej teplote so vzduchom na v\u00fdrobu oxidu hlinit\u00e9ho. Tento pr\u00edstup m\u00e1 mnoho v\u00fdhod oproti procesom, pri ktor\u00fdch sa vyu\u017e\u00edva kyselina s\u00edrov\u00e1 alebo dusi\u010dn\u00e1, preto\u017ee je jednoduch\u0161ie regenerova\u0165 kyselinu chlorovod\u00edkov\u00fa ako jej alternat\u00edvy.<\/p>\n
Predch\u00e1dzaj\u00face kalcina\u010dn\u00e9 procesy spotrebovali zna\u010dn\u00e9 mno\u017estvo energie na zv\u00fd\u0161enie teploty kry\u0161t\u00e1lov hexahydr\u00e1tu nad 500 - 1 100 \u00b0C na v\u00fdrobu oxidu hlinit\u00e9ho, ale ve\u013ek\u00e1 \u010das\u0165 tejto energie sa spotrebovala po\u010das n\u00edzkoteplotn\u00fdch f\u00e1z na extrakciu kombinovanej vody a zv\u00fd\u0161enie medziproduktov kry\u0161talickej formy hexahydr\u00e1tu. Okrem toho sa v ka\u017edej f\u00e1ze spotrebovala len \u010das\u0165 celkovej dostupnej energie.<\/p>\n
Bol vyvinut\u00fd inovat\u00edvny proces kalcin\u00e1cie, ktor\u00fd v\u00fdrazne zni\u017euje spotrebu energie vo vysokoteplotn\u00fdch aj chladiacich f\u00e1zach kalcin\u00e1cie, \u010d\u00edm sa v\u00fdrazne zni\u017euj\u00fa celkov\u00e9 energetick\u00e9 po\u017eiadavky na v\u00fdrobu oxidu hlinit\u00e9ho. Jeho z\u00e1kladom je syst\u00e9m v\u00fdmeny tepla, ktor\u00fd vyu\u017e\u00edva postupn\u00e9 zahrievanie hexahydr\u00e1tu cez viacer\u00e9 stupne v\u00fdmeny tepla na postupne vy\u0161\u0161ie teploty bl\u00ed\u017eiace sa k teplote kalcin\u00e1cie pred jeho dodan\u00edm do kalcin\u00e1tora na kone\u010dn\u00fa premenu na oxid hlinit\u00fd. Hexahydr\u00e1t sa \u010falej ochladzuje cez r\u00f4zne stupne v\u00fdmeny tepla, pri\u010dom cite\u013en\u00e9 teplo sa odovzd\u00e1va z chladiacich stup\u0148ov do ohrievac\u00edch stup\u0148ov len pri mierne vy\u0161\u0161\u00edch teplot\u00e1ch, ako s\u00fa teploty, pri ktor\u00fdch sa spotreb\u00fava v danom stupni.<\/p>","protected":false},"excerpt":{"rendered":"
Aluminium mining from bauxite is one of the world’s most complex industrial processes, involving an immense task of scientific and […]<\/p>\n","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":[6],"tags":[],"class_list":["post-90","post","type-post","status-publish","format-standard","hentry","category-alumina-knowledge"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/aluminaceramics.net\/sk\/wp-json\/wp\/v2\/posts\/90","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/aluminaceramics.net\/sk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/aluminaceramics.net\/sk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/aluminaceramics.net\/sk\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/aluminaceramics.net\/sk\/wp-json\/wp\/v2\/comments?post=90"}],"version-history":[{"count":1,"href":"https:\/\/aluminaceramics.net\/sk\/wp-json\/wp\/v2\/posts\/90\/revisions"}],"predecessor-version":[{"id":91,"href":"https:\/\/aluminaceramics.net\/sk\/wp-json\/wp\/v2\/posts\/90\/revisions\/91"}],"wp:attachment":[{"href":"https:\/\/aluminaceramics.net\/sk\/wp-json\/wp\/v2\/media?parent=90"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/aluminaceramics.net\/sk\/wp-json\/wp\/v2\/categories?post=90"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/aluminaceramics.net\/sk\/wp-json\/wp\/v2\/tags?post=90"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}