Zirconium thiab Hafnium Separation Technology Txoj Cai
Zirconium thiab hafnium yog siv nyob rau hauv ntau yam ntawm kev lag luam nuclear vim lawv qhov sib txawv tseem ceeb hauv neutron absorption cross-sectional area. Feem ntau, nyob rau hauv zirconium-hafnium alloys siv nyob rau hauv atomic reactors, ob yog "kev puas tsuaj" rau ib leeg. Txhawm rau tswj hwm cov khoom siv hluav taws xob ntawm zirconium thiab hafnium alloys, qee qhov yuav tsum tau muab tso rau pem hauv ntej rau cov ntsiab lus ntawm zirconium thiab hafnium alloys, uas yog, cov ntsiab lus ntawm hafnium hauv zirconium yuav tsum tsis txhob siab tshaj 100 ppm, thiab cov ntsiab lus ntawm zirconium hauv. hafnium yuav tsum tsis txhob siab tshaj 2%. Hauv qhov xwm txheej, zirconium thiab hafnium yeej ib txwm tsim ua ke, thiab tsis muaj zirconium lossis hafnium uas twb muaj lawm. Yog li ntawd, kev sib cais ntawm zirconium thiab hafnium tau dhau los ua tus yuam sij rau kev npaj ntawm nuclear-qib zirconium thiab hafnium. Hauv kev lag luam, ntau tus kws tshaj lij thiab cov kws tshawb fawb tau ua tiav txoj hauv kev sib txawv rau kev sib cais zirconium thiab hafnium, uas tuaj yeem faib ua ob pawg hauv qab no: pyro sib cais thiab kev sib cais ntub dej.
1. Pyro cais txoj kev ntawm zirconium thiab hafnium
Kev sib cais pyro ntawm zirconium thiab hafnium kuj yog lub ntsiab lus tseem ceeb ntawm kev tshawb fawb los ntawm cov kws tshawb fawb hauv ntau lub teb chaws. Raws li kev txheeb cais, muaj ntau txog 16 hom pyro sib cais ntawm zirconium thiab hafnium, ntawm cov neeg sawv cev feem ntau yog distillation thiab xaiv txo.
Txoj kev Distillation
Txoj kev Distillation yog raws li qhov tseeb tias qee qhov sib xyaw ntawm zirconium thiab hafnium, xws li chlorides thiab complex chlorides tsim los ntawm chlorides ntawm zirconium thiab hafnium thiab phosphorus oxychloride, muaj cov ntsiab lus kub sib txawv, thiab kev sib cais ntawm ob yog tiav los ntawm distillation. Txoj kev Distillation tuaj yeem muab faib ua ob pawg: txoj kev ua haujlwm siab-siab fractionation thiab molten ntsev distillation txoj kev. Tam sim no, tsuas yog molten ntsev distillation txoj kev tau ua tiav nyob rau hauv kev tsim khoom, thiab feem ntau siv molten ntsev distillation system yog KCl-AlCl3 thiab NaCl-KCl. Txoj kev no siv qhov sib txawv ntawm qhov vapor siab ntawm zirconium thiab hafnium tetrachlorides hauv cov kuab tshuaj xws li (molten ntsev KAlK4) kom cais lawv rau hauv ntauwd distillation.
Xaiv txoj kev txo qis
Txoj kev no yog raws li qhov tseeb tias nyob rau hauv qee yam kev mob, zirconium tetrahalides raug xaiv txo qis rau trihalides los yog disproportionated rau dihalides los ntawm zirconium ib leeg, thaum hafnium tetrahalides tsis los yog tsis tshua muaj txo, yog li widening lub vapor siab sib txawv ntawm zirconium thiab hafnium halides, thiab ces. cais zirconium thiab hafnium los ntawm ib leeg los ntawm distillation. Cov txheej txheem feem ntau muab faib ua peb theem. Hauv thawj theem, ZrCl4 raug txo qis cov tshuaj tiv thaiv ntawm 390-405 degree nyob rau hauv ib txwm siab; nyob rau theem thib ob, qhov tsis txaus ntseeg tshwm sim tshwm sim ntawm 420-450 degree . Ob theem saum toj no feem ntau yog rau purifying zirconium. Qhov thib peb theem yog rau purifying hafnium. Tom qab purification, cov ntsiab lus hafnium nyob rau hauv cov khoom raw nce ntawm 50% mus rau 70%.
Cov txheej txheem pyrometallurgical sib cais ntawm zirconium thiab hafnium ncaj qha siv zirconium tetrachloride thiab hafnium raws li cov ntaub ntawv raw, uas tuaj yeem txuas ncaj qha nrog cov txheej txheem hlau txo, tshem tawm cov txheej txheem nyuaj ntawm kev ua haujlwm sib cuam tshuam ntawm pyrometallurgy thiab dej txoj kev, thiab ua kom yooj yim cov txheej txheem ntws. Txawm li cas los xij, txoj kev no yuav tsum tau ua nyob rau ntawm qhov kub siab dua (350-500 degree), uas muaj cov kev xav tau siab rau cov khoom siv, thiab cov txheej txheem muaj qhov tsis zoo ntawm kev nyuaj rau kev ua kom huv huv impurities thiab kev nqis peev loj, thiab tsuas yog haum rau loj smelters.
2. Kev sib cais ntub dej ntawm zirconium thiab hafnium
Vim cov txheej txheem txheej txheej electron zoo sib xws thiab lanthanide contraction, zirconium thiab hafnium zoo sib xws hauv cov khoom siv tshuaj. Lawv muaj zog complexing peev xwm nrog oxygen, yog li lawv yooj yim heev rau hydrolyze thiab polymerize nyob rau hauv aqueous tov los tsim ntau hom complexes, uas kuj ua rau kom nyuaj ntawm zirconium thiab hafnium sib cais. Txawm li cas los xij, kuj muaj qee qhov sib txawv me ntsis hauv zirconium thiab hafnium hauv cov xov xwm sib txawv. Raws li qhov sib txawv me ntsis, cov kws tshawb fawb hauv tsev thiab txawv teb chaws tau ua tiav cov txheej txheem ntawm kev sib cais ntub dej rau zirconium thiab hafnium. Raws li nws cov kev faib tawm, nws tuaj yeem muab faib ua cov pawg hauv qab no: hnyav rho tawm, kev sib cais adsorption, membrane sib cais, micro-solvent extraction, ob-theem extraction, fractional crystallization thiab nag lossis daus, ntawm cov kuab tshuaj extraction cais yog feem ntau thiab kawm. txoj kev.
Solvent extraction, tseem hu ua kua-kua extraction, yog ib txoj kev ntawm kev sib cais thiab purifying solutes los ntawm kev siv cov sib txawv tis ntawm cov kuab tshuaj nyob rau hauv ob immiscible los yog ib feem miscible kua theem. Nws muaj qhov zoo ntawm cov khoom ntim loj, cov cuab yeej siv yooj yim, yooj yim automation, kev nyab xeeb thiab kev ua haujlwm ceev, thiab tus nqi qis, thiab siv dav hauv kev sib cais ntawm cov khoom. Cov txheej txheem tshem tawm cov kuab tshuaj Txij li Fisher thawj zaug siv MIBK los cais zirconium thiab hafnium hauv thiocyanate tov hauv xyoo 1947, cov kuab tshuaj rho tawm txoj kev sib cais tau ua rau lub sijhawm ntev thiab kev loj hlob, thiab cov txheej txheem sib txawv thiab cov extractants tau tsim ua tiav. Tam sim no, ob peb qhov tseem ceeb ntawm cov txheej txheem ntawm kev sib cais ntawm cov zirconium thiab hafnium solvent extraction tau raug tsim ua tiav: MIBK-HSCN system, txhim kho TBP system thiab TOA/N235-H2SO4 system.
MIBK-HSCN system
MIBK-HSCN txoj kev siv qhov sib txawv ntawm qhov muaj peev xwm ntawm Zr4+ thiab Hf4+ nrog SCN- ions kom nyiam tshaj tawm hafnium, thiab zirconium tseem nyob rau theem aqueous, yog li ua tiav kev sib cais ntawm zirconium thiab hafnium. Txij li thaum xyoo 1970, MIBK txoj kev tau siv ntau tshaj plaws zirconium thiab hafnium sib cais cov txheej txheem tsim khoom hauv ntiaj teb, thiab ze li ntawm 1/3 ntawm lub ntiaj teb cov qib zirconium thiab hafnium yog tsim los ntawm txoj kev no. Txawm li cas los xij, MIBK txoj kev muaj qee qhov tsis zoo: (1) MIBK muaj cov dej solubility siab (1.7%), ua rau cov kuab tshuaj loj loj; (2) Lub decomposition ntawm ammonium thiocyanate nyob rau hauv cov dej khib nyiab ua rau hydrogen sulfide, mercaptans thiab cyanide ions, uas muaj teeb meem rau ib puag ncig; (3) MIBK muaj qee yam tsw, uas ua rau lub chaw ua haujlwm rhiav ib puag ncig tsis zoo.
TBP system
Txoj kev TBP yog thawj zaug tsim los ntawm Fabkis tus txiv neej JV Kerrigan. Tom qab xyoo ntawm kev tshawb fawb txuas ntxiv thiab txhim kho los ntawm cov kws tshawb fawb hauv tsev thiab txawv teb chaws, nws cov txheej txheem tsis zoo thiab cov xwm txheej tau hloov pauv zoo heev piv rau yav dhau los. Tam sim no, TBP-HNO3-HCl sib xyaw cov kua qaub feem ntau yog siv hauv kev lag luam. Cov txheej txheem no ncaj qha siv zirconium tetrachloride ua cov khoom siv raw thiab ntxiv nitric acid kom ncaj qha npaj nitric acid-hydrochloric acid extraction tov ntawm zirconium (hafnium). Tom qab kev txhim kho, kev sib cais coefficient ntawm zirconium rau hafnium tau zoo heev, mus txog 30 ~ 40, thiab atomic-theem zirconium dioxide thiab hafnium dioxide tuaj yeem tau txais tib lub sijhawm tom qab ib qho kev rho tawm. Txawm li cas los xij, vim lub siab acidity ntawm TBP system, nws corrodes cov cuab yeej hnyav thiab yooj yim rau emulsify thaum lub sij hawm rho tawm, uas ncaj qha cuam tshuam rau kev ua haujlwm ntawm kev ua haujlwm ntawm kev rho tawm.
TOA/N235-H2SO4
Txoj kev TOA yog lwm txoj kev sib cais zirconium thiab hafnium tom qab MIBK txoj kev thiab TBP txoj kev. Txoj kev no siv sulfuric acid ua qhov nruab nrab, nyiam tshaj tawm zirconium, thiab kev sib cais coefficient ntawm zirconium thiab hafnium yog 8 ~ 10. TOA txoj kev muaj qhov zoo ntawm cov pa phem tsawg, cov khoom siv hluav taws xob muaj zog, kev tuav tau yooj yim, thiab cov nqi peev tsawg, tab sis cov peev txheej ntawm zirconium thiab hafnium yog me me thiab qhov sib cais coefficient tsis siab. Raws li qhov kev txwv ntawm TOA, cov kws tshawb fawb tshawb fawb tau ua ntau txoj kev tshawb fawb thiab kev txhim kho ntawm txoj kev no.
Txawm hais tias cov txheej txheem saum toj no tuaj yeem ua tiav cov kev xav tau ntawm kev sib cais ntawm zirconium thiab hafnium, lawv muaj qee qhov tsis zoo, xws li dej solubility ntawm MIBK siab, tsis tshua muaj boiling point, hnyav hnyav poob, hnyav ib puag ncig, thiab lwm yam .; TBP txheej txheem muaj kev xeb loj rau cov khoom siv thiab yooj yim rau emulsify, thiab lwm yam .; TOA txoj kev thiab N235 txoj kev muaj peev xwm rho tawm me me thiab qis sib cais coefficient, uas txwv lawv cov ntawv thov kev lag luam. Kev txhim kho cov txheej txheem ib txwm muaj thiab tsim cov txheej txheem tshiab ntawm zirconium thiab hafnium sib cais nrog kev sib cais siab coefficients yog lub hom phiaj tseem ceeb ntawm kev tshawb fawb thiab kev loj hlob cov lus qhia ntawm cov kuab tshuaj rho tawm tam sim no.
