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1、Surface Modification Mechanism of Fine Coal by Electrochemical MethodsJun.20o6J.ChinaUniv.ofMining&Tech.(EnglishEdition)Vb1.16No.2SurfaceModificationMechanismofFineCoalbyElectrochemicalMethodsZHUHong,WANGFang.hui,WANGDianZUO,OUZe.shenSchoolofScience,BeijingJiaotongUniversity,&fg100o44,ChinaB
2、eijingGenerafResearchforNonrrousMetals,Beijing100088.ChinaEngineeringandEnvironment,ChinaUniversityofMining&Technology,Xuzhou,Jiangsu221008.ChinaAbstract:Inordertorevealthesurfacemodificationmechanismoffinecoalbyelectrochemicalmethods.thestructuralchangesofthecoalsurfacebeforeandafterelectrochem
3、icalmodificationwereinvestigatedbyFourierTransfo衄In.fraredSpectra(FnR)andRamanSpectra.Theresultsshowthatundercertainelectrochemicalconditions.theoxy.gen-containingfunctionalgroupinthecoalstructureandtheoxygencontentofabsorptioncouldbereducedandthefloatabilityofcoalimproved.Atthesametime.thesulfurint
4、hecoalwasreducedtothehydrophilicSwhichcouldbeseparatedeasilyfromcoal功Uselectrochemicalmodificationmethodscouldbeusedtochangethestructureandfunc.tionalgrouponthecoalsurfaceandtoenhancethefloatabilityofcoa1.Keywords:finecoal;electrochemistrymodification;modificationmechanism;FTIR;RamanSpectraCLCnumber
5、:TQ028.94:X701.31IntroductionThereisavastamountofcoalinChina,butmostofitisdifficulttocleanduetoitshighashandsulfurcontent.Moremanhalfofthesulfurfoundinrawcoalisintheformofpyrite,whichisdistributedincoalinmicro.finesizesorcombinedwithcoa1.Coalmustbebrokentopiecestoincreasetherateofrecoveryofcleanedco
6、alandtodecreasesulfurandash.Flotationisaveryimportantandwidelyusedmethodfortheremovalofpyritefromhighsulfurcoa1.Ithasbeenreported山atafterinitialoxidation.thepyritesurfacecontainingoxidizedproductssuchaspolysulphideandfreesulfurisnaturallyhydrophobic.Therearevariouskindsofoxygen.containingfunctionalg
7、roupsincoa1.Themorehydrophilicthecoalis.themoregroupsthereareonthecoalsur.face1_41.一一Theprincipleofelectrochemicaldesulfurizationincoalflotationistomodifysurfacecharacteristiesofcoalandpyritebycontrollingcertainoperationalconditions.Asaresult,thepulposeofdesulfurizationinflotationCanbeachievedbydecr
8、easingtheflotati.bilitvofDvritesurfacesandenhancingthatofcoalsu矗cest5-由.一2ExperimentalMaterialsandConditions2.1MaterialsGascoalsamplestakenfromCachengCoalMine,Xuzhou,werebrokento0.40.2mmsizeandinjectedwithnitrogenareductant;C6H603apHregulatingagent;dilutedHCIanddilutedNaOH.2.2Measuringapparatusandco
9、nditionsThefollowingequipmentwasused.11FourierTransfo1TI1InfraredSpectra(FTIR1.Nicolet一510type,resolvingpowerof4,backgroundgainof2,scanningnumberof32,samplegainof200,scanningnumberof120.Diameterofsamplepoolof1cm.samplesizeof0.074iillllandsampleweightof5mg.2)RamanSpectra.RenishawRamanSystemMki2000typ
10、e.1aserwavelengthof514.5am.180.backscatteringinstallment.powerof9mW,lensmagnificationof20times.continuousscanningof10.3ResultsandDiscussion3.1FTIRspectraanalysesoffinecoalbeforeandaftersurfacemodificationUsingthereductantmethodandmetalcorrosioninteractionmethodtomodifythecoa1.theFTIPspectraoffinecoa
11、lbeforeandaftertreatmentareshowninFig.1.WlecanlearnfromFig.1thatmechangesofcharacteristicDeaksofcoalhavesomefeaturesincommon.1)TheabsorptionDeakof0Hweakensat360O一3100cm_.:2)theabsorptionpeakof>C=Oweakensat1700-1600cm-;3)theabsolptionpeakofSS一.一SHweakensslightlyat540-420Received20August2005;aCCept
12、ed15October2005Project50174054supportedbytheNationalNaturalScienceFoundationofChinaCorrespondingauthor.Tel:+861051688469,+8613161080285;Emailaddress:ZHUHongetalSurfaceModificationMechanismofFineCoalbyElectrochemicalMethodsl8lcm-.Theseresultsshowthatboththereductantmethodandmetalcorrosioninteractionm
13、ethodcandecreasethecontentofoxygencontainingfunctionalgroupsoncoalsurfacesandenhancethehydrophobicityofcoa1.3600280020001200400Wayenumber(cm)Fig.1FTIRspectraofgascoalbydifferentmodificationmethods1#isthecoalsamplewithouttreatment;2#isthecoalsampletreatedwiththereductantmethod;3#isthecoalsampletreate
14、dwithmetalcorrosioninteractionreduction3.2RamanspectraanalysesoffinecoalbeforeandaftersurfacemodificationRamanspectrabeforeandaftertreatmentbyelectrochemicalreductionareshowninFig.2.Line1istheRamanspectraofrawcoa1.Resultsshowthattherearesomechangesinpeak-intensityandpeakwidthafterthereaction,inparti
15、culartheweakeningoftheabsorotionpea1(Of0Hat34cmandof>C=0at1000cm.Becauseblacksuspensionisstronglycapableofabsorbinglaserbeamswithawavelengthof514.5am,Ramanspectraprovideuswithrepresentativecharacteristicsofthesamplesur-face.FromtheRamanspectraweseethatelectro.chemicalreductioncandecreasetheoxygencontajingfunctionalgroupsincoalstructure,modifyitssurface,andincreaseitssurfacehydrophobicity.TheFnRspectraabovealsoverifythesamechanges.There.sultsofRamanandFrIRspectraconfirmeachother.Researchresultsindicatethatelectrochemicalreduc.tionisanef
