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1、1832Ind.Eng.Chem.Res.2010,49,1832–1836LaboratoryStudiesonthePreparationProceduresofAluminaConvertedfromAluminumCitrate??,?,?ZhanglongYu,YajingLv,YongmeiChen,*andPingyuWan*SchoolofScience,BeijingUniVersityofChemicalTechnology,Beijing100029,People’sRepublicofChina,andSchoolofPhysicsandCh
2、emistry,XihuaUniVersity,Chengdu610039,People’sRepublicofChinaItisapromisingtechnologyinthealuminaindustryusingcitricacidtoextractaluminumfromclayorkaolinandobtainthesolutionofaluminumcitrate(AlCit).ButtheprerequisiteofthepreparationprocedureofaluminastartedfromAlCitisthatcitricacidshou
3、ldberecycled.AprocessnamedAlCit-Dawsonite-aluminaisproposedinthispaper.ByusingDawsoniteasanintermediate,citrategroupscouldbeseparatedandreused.Theprocesswasveri?edinlaboratoryscale:First,DawsonitewasprecipitatedfromAlCitsolutionwithasatis?edpurityandconversionrate.Second,Dawsonitewastr
4、ansformedtoaluminawithlowNacontentthroughthetwoproposedmethods.ThestructureandpurityoftheintermediateofDawsoniteandproductsofaluminawerecharacterizedbyinfrared,thermogravimetric-differentialthermalanalysis,X-raydiffraction,scanningelectronmicroscopy,andinductivelycoupledplasma.Theresul
5、tsshowthatthesynthesizedDawsonitehasagreatpurityandperfectcrystallinity;andtheNacontentofthe?nalaluminaproductislowerthan0.2%.1.IntroductioninsteadofAl2O3,andNaAlO2istreatedasimpurityto?nalaluminaproduct.MostaluminaproductsintheworldareproducedbytheAmethodtryingtotransformDawsonitetoal
6、uminaisBayerprocessfrombauxite.However,itisnoteconomicalfor10describedinaU.S.patentpublishedin1969,inwhichbauxitewitharatioofAl/Sibelow7orFecontentmorethanDawsoniteis?rstroastedat480°Ctobepartiallydecomposed20%becauseextraalkaliandenergyareconsumed.SomecountriessuchasChinahaverichreser
7、vesofclayminerals,intosodiumcarbonateandamorphousalumina,thensodiumsuchaskaoliniteandhalloysite.Someresearcherstriedtoleachcarbonateiscarefullywashedout,and?nallytheresidueisclayorkaolinbycitricacid.1,2Theyfoundthattheextractingroastedcontinuouslytoobtaincrystallinealumina.Actually,s
