Cr2O3制備方法(中英文方法)-論文指導(dǎo)設(shè)計(jì)-

Primary

chromium

productionChromium

oresCrocoite

(PbCrO4)Chromite(FeCr2O4;MgCr2O4)monoclinic

crystal

systemisometric

crystal

systemIntroduction

of

Chromium

oresCrocoiteCrocoiteisamineralconsistingofleadchromate,PbCrO4,andcrystallizingithemonocliniccrystalsystem.Itiscommonlyfoundaslarge,well-developedprismaticcrystals,althoughinmanycasesarepoorlyterminated.OnexposuretoUVlightsomeofthetranslucencyandbrilliancyislost.ChromiteChromiteistheonlyvaluableoreofchromiumtoproductchromium（III）oxide.Chromiteisanoxidemineralcomposedofchromium,ironandoxygen(FeCr2O4).Itisadarkgraytoblackincolorwithametallictosubmetallicluandahighspecificgravity.Itoccursinbasicandultrabasicigneousrocksaninthemetamorphicandsedimentaryrocksthatareproducedwhenchromite-bearingrocksarealteredbyheatorweathering.Identification

of

Chromate

MineralIndustrial

production

of

Cr2O3（solid-phase

synthesis）Intheindustryfieldsthegeneralproductionmethodissolid-phasereactionbycalciningCrO3.Undertheconditionsof700℃and90minutes,when2%~3%ofthecombustiblepowderandtheadequatewaterwereadded,itshowedthatthesizeofCr2O3powderwasabout200nm.以鉻酸酐熱分解制備Cr2O3工藝為基礎(chǔ),在可燃性粉末質(zhì)量分?jǐn)?shù)2%~3%、適量水,溫度為700℃,時(shí)間為90min的條件下,可得到平均粒徑為200nm,分散性良好的Cr2O3微粒。Solid-phase

Reaction

Process(the

reaction

principles)Calcining

CrO3:The

overall

reaction

:4CrO3

2Cr2O3+3O2Solid-phase

Synthesis

Process（preparation）CrO3

HCrO4remove

inflammable

powder

Cr2O3Industrial

production

of

Cr2O3（calcining

chromium

hydroxide）Thesodiumchromatesolutionwasaddedsulfurtoreducehexavalentchromiumtotrivalentchromium，thenformingtheprecipitationofchromiumhydroxide.atlastgeneratingchromiumoxidebycalciningchromiumhydroxide.氫氧化鉻法:將鉻酸鈉溶液加入硫磺還原鉻酸鈉溶液，使鉻從六價(jià)還原成三價(jià)從而形成氫氧化鉻沉淀，然后煅燒脫水變成氧化鉻。反應(yīng)式:4Na2CrO4+6S+7H2O=4Cr(OH)3↓+3Na2S2O3+2NaOH2Cr(OH)3=Cr2O3+3H2OCalcining

chromium

hydroxide（preparation）硫磺塊破碎機(jī)球磨機(jī)水或上液層反應(yīng)罐鉻酸鈉溶液蒸汽水管式過(guò)濾器上層液制硫代硫酸或碳酸鈉洗滌罐硫酸離心分離機(jī)煅燒水破碎氧化鉻laboratory

preparation

of

Cr2O3Experimentalprinciple:HydrothermaltechniquebythereactionsystemofCrO3andHCHOinaqueoussolutionExperimentalprocedure:5gCrO3and3.5mlHCHOaqueoussolutionwereaddedintoa200mlTeflon-linedcylindricalbombpreviouslyfilledwith120gdeionizedwater,andmagneticallystirredforseveralminutesuntiltheybecameahomogeneoussolution.Thenthesealedbombwasheatedat170℃for1hinanoven.Afterthat,itwascooledtoroomtemperatureandthesolutionwasfiltered.Thefiltercakewaswashedfor3times.Thenthecakewasdriedat100℃for5h.Theobtainedparticleswereblack,withsizeinthegradeofμmtomm.laboratory

preparation

of

Cr2O3The

possible

mechanism

was

concluded

as

follows:laboratory

preparation

of

Cr2O3Prospect:Thehydrothermalsynthesisneedsnosurfactantorstirrer.Andhighercalcinationtemperatureandhighertotalconcentrationcouldresultinlargeraveragepar-ticlesi