Qhov xwm txheej ntawm chromium
Chromium, lub cim ntawm Cr, tus lej atomic 24, qhov hnyav atomic 51.996, yog ib feem ntawm cov hlau hloov pauv ntawm pawg VIB ntawm lub rooj tshuaj lom neeg. Hlau Chromium yog lub cev siv lead ua cubic, nyiaj-dawb, qhov ceev 7.1g / cm³, melting point 1860 ℃, boiling point 2680 ℃, muaj peev xwm kub tshwj xeeb ntawm 25 ℃ 23.35J / (mol · K), cua sov ntawm vaporization 342.1kJ / mol, thermal conductivity 91.3 W / (m · K) (0-100 ° C), resistivity (20 ° C) 13.2uΩ · cm, nrog cov khoom siv kho tshuab zoo.
Muaj tsib qhov valences ntawm chromium: +2, +3, +4, +5 thiab +6. Nyob rau hauv cov xwm txheej ntawm endogenous kev ua haujlwm, chromium feem ntau yog +3 valence. Cov tshuaj sib xyaw nrog +trivalent chromium yog qhov ruaj khov tshaj plaws. +Sixvalent chromium compounds, suav nrog chromium ntsev, muaj cov khoom oxidizing muaj zog. Lub ionic radii ntawm Cr3 +, AI3 + thiab Fe3 + zoo sib xws, yog li lawv tuaj yeem muaj ntau yam zoo sib xws. Tsis tas li ntawd, cov ntsiab lus uas tuaj yeem hloov nrog chromium yog manganese, magnesium, nickel, cobalt, zinc, thiab lwm yam, yog li chromium tau faib dav hauv magnesium hlau silicate minerals thiab accessory minerals.
Daim Ntawv Thov
Chromium yog ib qho ntawm cov hlau siv dav tshaj plaws hauv kev lag luam niaj hnub no. Nws feem ntau yog siv rau hauv kev tsim cov hlau tsis xeb thiab ntau yam hlau sib xyaw ua ke hauv daim ntawv ntawm ferroalloys (xws li ferrochrome). Chromium muaj cov yam ntxwv ntawm kev tawv, hnav-resistant, kub-resistant thiab corrosion-resistant. Chrome ore yog dav siv hauv metallurgy, refractory cov ntaub ntawv, kev lag luam tshuaj lom neeg thiab kev lag luam foundry.
Hauv kev lag luam hlau, chromium ore feem ntau yog siv los ua kom ferrochrome thiab chromium hlau. Chromium yog siv los ua cov hlau ntxiv los tsim ntau yam hlau tshwj xeeb uas muaj zog, tiv taus corrosion, hnav-resistant, kub siab, thiab oxidation-resistant, xws li stainless hlau, acid-resistant steel, kub-resistant steel, pob bearing steel, caij nplooj ntoos hlav steel, cuab yeej steel, thiab lwm yam. Chromium tuaj yeem txhim kho cov khoom siv kho tshuab thiab hnav-resistant ntawm hlau. Hlau chromium feem ntau yog siv los ua kom cov hlau tshwj xeeb nrog cobalt, nickel, tungsten thiab lwm yam ntsiab lus. Chrome plating thiab chromizing tuaj yeem ua rau hlau, tooj liab, txhuas thiab lwm yam hlau tsim ib qho chaw tiv taus corrosion, uas yog ci thiab zoo nkauj.
Hauv kev lag luam refractory, chromium ore yog ib qho khoom siv refractory tseem ceeb uas siv los ua chrome cib, chrome magnesia cib, advanced refractories thiab lwm yam khoom siv refractory tshwj xeeb (chrome concrete). Chromium-based refractories feem ntau suav nrog chrome ore thiab magnesia cib, sintered magnesia-chrome clinker, molten magnesia-chrome cib, molten, finely grounded thiab tom qab ntawd bonded magnesia-chrome cib. Lawv siv dav hauv qhov cub qhib hearth, induction cub, thiab lwm yam. Metallurgical converter thiab rotary furnace lining ntawm cement kev lag luam, thiab lwm yam.
Hauv kev lag luam foundry, chromium ore yuav tsis cuam tshuam nrog lwm yam khoom hauv cov hlau molten thaum lub sijhawm nchuav, muaj cov coefficient thermal expansion qis, tiv taus hlau nkag mus, thiab muaj kev ua haujlwm txias zoo dua li zircon. Chrome ore rau foundry muaj cov kev cai nruj ntawm cov tshuaj lom neeg thiab kev faib tawm ntawm cov khoom me me.
Hauv kev lag luam tshuaj lom neeg, kev siv chromium ncaj qha tshaj plaws yog los tsim cov tshuaj sodium dichromate (Na2Cr2O7 · H2O), thiab tom qab ntawd los npaj lwm cov tshuaj chromium rau kev siv hauv kev lag luam xws li cov xim, textiles, electroplating, thiab tawv ua, nrog rau cov catalysts.
Cov hmoov chromium ore uas tau zom zoo yog ib yam khoom siv xim ntuj tsim rau kev tsim cov iav, cov khoom siv av nplaum thiab cov vuas glazed. Thaum sodium dichromate siv los rhuav tshem tawv, cov protein (collagen) thiab cov carbohydrates hauv cov tawv thawj zaug yuav ua rau cov tshuaj lom neeg sib xyaw ua ke, uas ua rau cov khoom tawv muaj zog. Hauv kev lag luam textile, sodium dichromate siv los ua mordant hauv kev zas xim ntaub, uas tuaj yeem txuas cov xim rau cov organic sib xyaw; nws kuj tseem siv tau ua oxidant hauv kev tsim cov xim thiab cov khoom nruab nrab.
Cov ntxhia chromium
Muaj ntau tshaj 50 hom chromium uas tau pom nyob rau hauv xwm, tab sis feem ntau ntawm lawv muaj cov chromium tsawg thiab kev faib tawm, uas muaj txiaj ntsig tsawg rau kev siv hauv kev lag luam. Cov chromium-muaj cov minerals no yog oxides, chromates thiab silicates, ntxiv rau ob peb hydroxides, iodates, nitrides thiab sulfides. Ntawm lawv, chromium nitride thiab chromium sulfide minerals tsuas pom nyob rau hauv meteorites.
Raws li ib hom minerals hauv chromium ore subfamily, chromite yog tib qho tseem ceeb industrial minerals ntawm chromium. Cov mis tshuaj theoretical yog (MgFe) Cr2O4, uas Cr2O3 cov ntsiab lus suav rau 68%, thiab FeO suav rau 32%. Hauv nws cov tshuaj lom neeg sib xyaw, cov cation trivalent feem ntau yog Cr3 +, thiab feem ntau muaj Al3 +, Fe3 + thiab Mg2 +, Fe2 + isomorphic hloov. Hauv cov chromite tsim tawm tiag tiag, ib feem ntawm Fe2 + feem ntau hloov los ntawm Mg2 +, thiab Cr3 + hloov los ntawm Al3 + thiab Fe3 + rau ntau qib. Qhov tiav ntawm isomorphic hloov ntawm ntau yam khoom ntawm chromite tsis sib xws. Plaub-kev sib koom tes cations feem ntau yog magnesium thiab hlau, thiab qhov tiav isomorphic hloov ntawm magnesium-hlau. Raws li txoj kev faib plaub, chromite tuaj yeem muab faib ua plaub pawg me: magnesium chromite, hlau-magnesium chromite, mafic-hlau chromite thiab hlau-chromite. Tsis tas li ntawd, chromite feem ntau muaj me ntsis manganese, Ib qho sib xyaw ua ke ntawm titanium, vanadium thiab zinc. Cov qauv ntawm chromite yog hom spinel ib txwm muaj.
4. Tus qauv zoo ntawm chromium concentrate
Raws li cov txheej txheem ua tiav sib txawv (mineralization thiab natural ore), chromium ore rau metallurgy yog muab faib ua ob hom: concentrate (G) thiab lump ore (K). Saib lub rooj hauv qab no.
Cov kev cai zoo rau cov chromite ore rau metallurgy
Kev siv tshuab ua kom zoo ntawm chrome ore
1) Kev xaiv tsa dua tshiab
Tam sim no, kev sib cais ntawm lub ntiajteb txawj nqus yog ib qho tseem ceeb hauv kev ua kom cov chromium ore zoo dua. Txoj kev sib cais ntawm lub ntiajteb txawj nqus, uas siv cov txheej txheej xoob hauv cov dej nruab nrab ua tus cwj pwm yooj yim, tseem yog txoj hauv kev tseem ceeb rau kev nplua nuj chromium ore thoob ntiaj teb. Cov khoom siv sib cais ntawm lub ntiajteb txawj nqus yog lub chute kauv thiab lub centrifugal concentrator, thiab qhov loj me ntawm cov khoom ua tiav yog qhov dav heev. Feem ntau, qhov sib txawv ntawm cov zaub mov chromium thiab cov zaub mov gangue yog ntau dua 0.8g / cm3, thiab kev sib cais ntawm lub ntiajteb txawj nqus ntawm txhua qhov loj me loj dua 100um tuaj yeem txaus siab. Qhov tshwm sim ntawm. Cov pob zeb loj (100 ~ 0.5 hli) ore raug txheeb xyuas lossis xaiv ua ntej los ntawm kev ua kom hnyav-nruab nrab, uas yog txoj hauv kev ua kom zoo dua qub.
2) Kev sib cais sib nqus
Kev sib cais sib nqus yog ib txoj kev ua kom zoo uas ua rau muaj kev sib cais ntawm cov zaub mov hauv lub teb sib nqus tsis sib xws raws li qhov sib txawv ntawm cov zaub mov hauv cov hlau. Chromite muaj cov khoom sib nqus tsis muaj zog thiab tuaj yeem sib cais los ntawm cov sib cais sib nqus ntsug, cov sib cais sib nqus phaj ntub thiab lwm yam khoom siv. Cov coefficients tshwj xeeb ntawm cov zaub mov chromium tsim tawm hauv ntau thaj chaw tsim cov chromium ore hauv ntiaj teb tsis txawv ntau, thiab zoo ib yam li cov coefficients tshwj xeeb ntawm wolframite thiab wolframite tsim tawm hauv ntau thaj chaw.
Muaj ob qho xwm txheej hauv kev siv kev sib cais sib nqus kom tau txais cov chromium concentrate zoo: ib qho yog tshem tawm cov minerals sib nqus muaj zog (feem ntau yog magnetite) hauv cov ore hauv qab lub zog sib nqus tsis muaj zog kom nce qhov piv ntawm ferrochrome, thiab lwm qhov yog siv lub zog sib nqus muaj zog. Kev sib cais ntawm cov minerals gangue thiab rov qab tau cov chromium ore (cov minerals sib nqus tsis muaj zog).
3) Kev xaiv hluav taws xob
Kev sib cais hluav taws xob yog ib txoj kev sib cais cov chromium ore thiab silicate gangue minerals los ntawm kev siv cov khoom hluav taws xob ntawm cov minerals, xws li qhov sib txawv ntawm conductivity thiab dielectric constant.
4) Kev ntab dej
Hauv cov txheej txheem ntawm kev sib cais ntawm lub ntiajteb txawj nqus, cov chromite ore uas zoo (-100um) feem ntau raug pov tseg ua cov tailings, tab sis cov chromite ntawm qhov loj no tseem muaj txiaj ntsig zoo, yog li txoj kev flotation tuaj yeem siv rau cov granular chromite ore uas zoo qis dua tau rov qab los. Kev flotation ntawm chromium ore nrog 20% ~ 40% Cr2O3 hauv cov tailings thiab serpentine, olivine, rutile thiab calcium magnesium carbonate minerals ua cov gangue minerals. Cov ore yog finely av rau 200μm, dej iav, phosphate, metaphosphate, fluorosilicate, thiab lwm yam yog siv los disperse thiab inhibit cov sludge, thiab unsaturated fatty acid yog siv ua tus sau. Kev disperse thiab suppression ntawm gangue sludge yog qhov tseem ceeb heev rau cov txheej txheem flotation. Cov hlau ions xws li hlau thiab txhuas tuaj yeem ua kom chromite ua haujlwm. Thaum tus nqi pH ntawm cov slurry qis dua 6, chromite yuav tsis ntab. Hauv ntej, kev siv cov reagent flotation yog loj, qib concentrate tsis ruaj khov, thiab tus nqi rov qab yog qis. Ca2+ thiab Mg2+ yaj los ntawm cov zaub mov gangue txo qhov kev xaiv ntawm cov txheej txheem flotation.
5) Kev siv tshuaj lom neeg
Txoj kev siv tshuaj lom neeg yog kho ncaj qha rau qee cov chromite ore uas tsis tuaj yeem sib cais los ntawm txoj kev siv lub cev lossis tus nqi ntawm txoj kev siv lub cev siab heev. Qhov piv ntawm Cr/Fe ntawm cov concentrate uas tsim los ntawm txoj kev siv tshuaj lom neeg siab dua li ntawm txoj kev siv lub cev ib txwm muaj. Txoj kev siv tshuaj lom neeg suav nrog: kev xaiv leaching, kev txo oxidation, kev sib cais yaj, kev leaching sulfuric acid thiab chromic acid, kev txo qis thiab kev leaching sulfuric acid, thiab lwm yam. Kev sib xyaw ua ke ntawm txoj kev siv lub cev thiab tshuaj lom neeg thiab kev kho ncaj qha rau chromite ore los ntawm txoj kev siv tshuaj lom neeg yog ib qho ntawm cov qauv tseem ceeb hauv kev ua kom chromite zoo niaj hnub no. Txoj kev siv tshuaj lom neeg tuaj yeem rho tawm chromium los ntawm cov ore ncaj qha thiab tsim cov chromium carbide thiab chromium oxide.
Lub sijhawm tshaj tawm: Plaub Hlis-30-2021