CrO制备方法中英文方法.ppt

Primarychromiumproduction Chromiumores Crocoite PbCrO4 Chromite FeCr2O4 MgCr2O4 monocliniccrystalsystemisometriccrystalsystem IntroductionofChromiumores Crocoite Crocoiteisamineralconsistingofleadchromate PbCrO4 andcrystallizinginthemonocliniccrystalsystem Itiscommonlyfoundaslarge well developedprismaticcrystals althoughinmanycasesarepoorlyterminated OnexposuretoUVlightsomeofthetranslucencyandbrilliancyislost Chromiteistheonlyvaluableoreofchromiumtoproductchromium III oxide Chromiteisanoxidemineralcomposedofchromium ironandoxygen FeCr2O4 Itisadarkgraytoblackincolorwithametallictosubmetalliclusterandahighspecificgravity Itoccursinbasicandultrabasicigneousrocksandinthemetamorphicandsedimentaryrocksthatareproducedwhenchromite bearingrocksarealteredbyheatorweathering Chromite IdentificationofChromateMinerals IndustrialproductionofCr2O3 solid phasesynthesis 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 phaseReactionProcess thereactionprinciples CalciningCrO3 Theoverallreaction 4CrO32Cr2O3 3O2 CrO3HCrO4removeinflammablepowderCr2O3 Solid phaseSynthesisProcess preparation IndustrialproductionofCr2O3 calciningchromiumhydroxide 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 3H2O Calciningchromiumhydroxide preparation 破碎机 硫磺块 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 laboratorypreparationofCr2O3 Experimentalprinciple HydrothermaltechniquebythereactionsystemofCrO3andHCHOinaqueoussolutionExperimentalprocedure 5gCrO3and3 5mlHCHOaqueoussolutionwereaddedintoa200mlTeflon linedcylindricalbombpreviouslyfilledwith120gdeionizedwater andmagneticallystirredforseveralminutesuntiltheybecameahomogeneoussolution Thenthesealedbombwasheatedat170 for1hinanoven Afterthat itwascooledtoroomtemperatureandthesolutionwasfiltered Thefiltercakewaswashedfor3times Thenthecakewasdriedat100 for5h Theobtainedparticleswereblack withsizeinthegradeof mtomm laboratorypreparationofCr2O3 Thepossiblemechanismwasconcludedasfollows laboratorypreparationofCr2O3 Prospect Thehydrothermalsynthesisneedsnosurfactantorstirrer Andhighercalcinationtemperatureandhighertotalconcentrationcouldresultinlargeraveragepar ticlesize Theprocesswaseasilycontrolledandthereactiontimeonlyneeded1h Fortheadvantagesofit thisprocesshasthepotentialtobeappliedintotheindustry END