Cr2O3制备方法(中英文方法)-论文指导设计-

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.以铬酸酐热分解制备Cr2O3工艺为基础,在可燃性粉末质量分数2%~3%、适量水,温度为700℃,时间为90min的条件下,可得到平均粒径为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.氢氧化铬法:将铬酸钠溶液加入硫磺还原铬酸钠溶液，使铬从六价还原成三价从而形成氢氧化铬沉淀，然后煅烧脱水变成氧化铬。反应式:4Na2CrO4+6S+7H2O=4Cr(OH)3↓+3Na2S2O3+2NaOH2Cr(OH)3=Cr2O3+3H2OCalcining

chromium

hydroxide（preparation）硫磺块破碎机球磨机水或上液层反应罐铬酸钠溶液蒸汽水管式过滤器上层液制硫代硫酸或碳酸钠洗涤罐硫酸离心分离机煅烧水破碎氧化铬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