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MainpointsforcoalchemistryⅠ.Blank-filling1.Ligninandcelluloseareconsideredtobethemajororganicprecursorstocoalalthoughthereislittleevidencetosupportthistheory.2.Themicroscopicconstituentsofcoalsarecalledmacerals.Themaceralsareactuallyidentifiedmicroscopicallybytheirformandreflectivity,andaredivisibleintothreegroupsbasedappearanceandphysicalcharacteristics—vitrinite,exinite,andinertinite—areeachfurthersubdividedonthebasisofindividualmaceralform.3.Theashingtechniqueiscommonlytomakeacoalcompletelycombustedatquiteahightemperaturebyusingaspecialdevice—amufflefurnace,thentoweightheresidue,i.e.,theash,andtousetheashcontentasanindicationtothemineralsinthecoal.4.Theproximateanalysisofcoalmaybeconsideredasthedeterminationoftheoverallcompositionofacoalsampleandis,inreality,thedeterminationofmoisturecontent,volatilemattercontent,ashcontent,and(bydifference)fixedcarboncontent.5.Fixedcarbonisameasureofthesolidcombustiblematerialincoalaftertheexpulsionofvolatilematter;fixedcarbonplusashrepresenttheapproximateyieldofcokefromcoal.Thefixedcarbonvalueisdetermined(ASTMD3172)bysubtractingfrom100theresultantsummationofmoisture,volatilematter,andashwithallpercentagesonthesamemoisturereferencebase.6.Themakeupoftheorganicportionofplantsconsistsofcarbohydrates,lignin,proteinsandlipoids.7.Coalisakindofsedimentaryorganicrockoriginatingfromancientplantremainsundergonecomplicatedlybiochemicalandphysicochemicalchangesundercertainclimatic,biological,environmentalandgeologicalconditions.8.Apieceofhumiccoalcanbeidentifiedasbrightcoals(anthraxylon)ordullcoals(attritus).Theformerhavebeenfurthersubdividedintovitrainandclarainwhilethelateraresubdividedintofusainanddurain.Eachoftheselithotypeshasindividualcharacteristicsthatareeasilydistinguishable.9.Avarietyofmineralshavebeenreportedtobepresentincoals，involvingClayminerals,Quartzminerals,Carbonateminerals,andSulfurminerals.Mineralmatterincoalcanbeevaluatedbyusingashingtechniques,ashanalysisanddirectmineralanalysis.10.Thetwomajorsapropeliticcoalsarecannelcoalandbogheadcoal(thelatterisalsowellknownastorbanite).11.Themaceralsareactuallyidentifiedmicroscopicallybytheirformandreflectivity，andaredivisibleintothreegroupsbasedappearanceandphysicalcharacteristics(Table3-3).Thethreemaingroups－vitrinite(sometimescalledhuminiteinsubbitumiouscoals),exinite(sometimescalledliptinite),andinertinite–areeachfurthersubdividedonthebasisofindividualmaceralform.Ⅱ.Explanationoftermsofcoalchemistry1.CoalpetrographyCoalpetrographyis,inessence,aninvestigationwithsubsequentidentificationofthemacrostructuresandmicrostructuresthatarethephysicalstructureofcoal.2.UltimateanalysisofcoalUltimateanalysisisanabsolutemeasureoftheelementalcompositionofcoal,expressesthecompositionofcoalinpercentagesofcarbon,hydrogen,nitrogen,sulfur,oxygen,andash.3.ThecalorificvalueofcoalThecalorificvalueofcoalisadirectindicationoftheenergyvalueofthecoalandthisparticularpropertyisconsideredtobeoneofthemostimportantmeansbywhichacoalcanbeevaluated.4.AshtechniquetodetecttheashcontentofcoalThistechniqueiscommonlytomakeacoalcompletelycombusted(燃烧)atquiteahightemperaturebyusingaspecialdevice(amufflefurnace),thentoweigh(称量)theresidue(残渣),i.e.,theash(灰分),andtousetheashcontentasanindicationtothemineralsinthecoal.Ⅲ.Comprehensiveunderstanding1.Pleasebrieflydescribethecoalformingprocessfromtheancienthigherplantremainstothesubstanceweknowascoaltoday,accordingtothefollowingschematicgraph.Coalwasformedfrompartiallydecomposed(已降解的，已腐烂的）(andsubsequently(后来，随后）metamorphosed(变质，变形）)plantdebris(碎片，残骸）whichcollectedinregionswherewaterlogged(浸满水的，涝的）orswampy(沼泽的，湿地的）conditionsprevailed(流行，盛行，占优势）.Theseconditionspreventedcompletedecay(腐烂，降解）ofthedebrisasitaccumulatedandeventually(最后的）ledtothematerialnowascoal.Ingeneralterms,thedebrisconsistedoftrees,ferns（蕨类植物）,rushes（灯芯草，灌木）,lycopods（石松属植物）,andseveralthousandplantspeciesthathavebeenidentifiedincoalbeds,butitappearsthatnoneofthespeciesidentifiedinmanydifferentcoalsoriginatedinbrackish-water（盐水）locales（区域）.Similartypesofplantremainsmaybefoundinalltypes(ranks（煤阶）)ofcoal，but,ofcourse,therelativeamounts（相对含量）varyconsiderably（相当地，非常地）.Onthisbasis（由此）,itisnotsurprisingthatcoaldiffersmarkedly（显著地）incompositionfromoneparticularseamarenotuncommon,duenotonlytothewidevarietyofplantdebristhatcouldhaveformedtheprecursors（母体，前体）butalsotothemanydifferentchemicalreactionsthatcanoccurduringthematuration（成熟）process.Thus,onceplantdebrishasaccumulatedunderthe“correct”conditions,theformationofpeat（泥炭）graduallyoccurs（发生，出现）.Peatisnotactuallyclassifiedascoalbutitis,nevertheless（仍然，不过）,believedtobethatmaterialwhichisformedastheinitialstepintheprocess.However,tobecomecoal,peatPlantsPeatsapropelPeatificationLignitesapropeliccoalBituminousAnthraciteStone-likecoalDiagenisis/lignificationMetamorphismcoalificationBituminizationanthracizationsaproficationDiagenisisorlignificationcoalificationmustprogress（前进，进展，经历）throughwhatislooselytermed“coalification”（煤化作用）process.Thecoalificationprocessis,inessence（本质）,theprogressive（渐进的，累进的）changeintheplantdebrisas