Laboratory Studies on the Preparation Procedures of Alumina Converted from Aluminum Citrate.pdf

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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.Theprocesswasverifiedinlaboratoryscale:First,DawsonitewasprecipitatedfromAlCitsolutionwithasatisfiedpurityandconversionrate.Second,Dawsonitewastr

4、ansformedtoaluminawithlowNacontentthroughthetwoproposedmethods.ThestructureandpurityoftheintermediateofDawsoniteandproductsofaluminawerecharacterizedbyinfrared,thermogravimetric-differentialthermalanalysis,X-raydiffraction,scanningelectronmicroscopy,andinductivelycoupledplasma.Theresul

5、tsshowthatthesynthesizedDawsonitehasagreatpurityandperfectcrystallinity;andtheNacontentofthefinalaluminaproductislowerthan0.2%.1.IntroductioninsteadofAl2O3,andNaAlO2istreatedasimpuritytofinalaluminaproduct.MostaluminaproductsintheworldareproducedbytheAmethodtryingtotransformDawsonitetoal

6、uminaisBayerprocessfrombauxite.However,itisnoteconomicalfor10describedinaU.S.patentpublishedin1969,inwhichbauxitewitharatioofAl/Sibelow7orFecontentmorethanDawsoniteisfirstroastedat480°Ctobepartiallydecomposed20%becauseextraalkaliandenergyareconsumed.SomecountriessuchasChinahaverichreser

7、vesofclayminerals,intosodiumcarbonateandamorphousalumina,thensodiumsuchaskaoliniteandhalloysite.Someresearcherstriedtoleachcarbonateiscarefullywashedout,andfinallytheresidueisclayorkaolinbycitricacid.1,2Theyfoundthattheextractingroastedcontinuouslytoobtaincrystallinealumina.Actually,s