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共2页第1页中国矿业大学（北京）研究生课程考试试题考试科目：专业外语（矿物加工类）考试时间：2小时1.Gravityseparation,whichisgovernedbythedifferencesinspecificgravitybetweencoalandmineralmatters(ash-formingmineralsandpyrite),iswidelyusedinthecoalpreparation.Amonggravityseparationtechniques,densemediumseparationisoneofthemostprevalentprocesses.Othergravityseparationtechniquesincludecentrifuge,jig,launders,etc.Despiteitsefficiencyinashremovalforrelativelycoarsecoal,theyarenotsousefulinfinecoalcleaning.1.重力分选是一种广泛运用选煤的分选方法，其分选原理是由于煤与矿物质（成灰矿物和黄铁矿）的比重不同。在重力分选的方法中，重介质分选是最普遍的一种分选方法。其它的重力分选方法包括离心机分选，跳汰分选，溜槽分选等。尽管它们对大块煤脱灰有效，但对于洗精煤的分选并不是非常有效。2．Awashabilitystudyofacoalismadebytestingthecoalsampleatpreselected,carefullycontrolleddensities(specificgravities).Thisiscommonlytermedfloat-and-sinkanalysisand/orspecific-gravityfractionation.Thespecific-gravityfractionsaredried,weighed,andanalyzed,generallyforashcontent.Otheranalyses,suchassulfurcontent,arealsoconducted,dependingontheenduseofthewashedcoal.Atableiscompiledshowingtheweightpercentofeachspecific-gravityfractiontogetherwiththeanalysesofeachfraction.Thedataaremathematicallycombinedonaweightedbasisintocumulativefloatandcumulativesinkandusedtodevelopthewashabilitycurvesthatarecharacteristicforthecoal.2.煤的可选性研究是通过对预选煤样严格按密度（比重）进行试验，这通常被称为浮沉试验或比重分离试验。通常对密度级组分进行干燥，称重，分析得到灰分含量。根据洗精煤最终的用途还要对其它成分比如硫含量进行分析。通过对不同密度级的分析，制成能显示不同的密度级的重量百分数的表。通过对浮物和沉物这些数据进行算数加权求和，绘制出能显示煤样特征的可选性曲线。3.Ashisgenerallywellintermixedintothecoalstructureandhencecoalwashingusingphysicalmethodsisdifficult,althoughitmightbesimpleandnecessaryforindustrialuse.Someofthelimitationsofphysicalcoalcleaningaregivenhere：Veryfinegrindingisrequiredtoliberatethefinepyriteinclusions.Finegrindingismostenergyintensiveoperationandultrafineparticlesaredifficulttohandleanddewater.Desulfurizationincreaseswithgrindingtofinersizebutdecreasesdensityoftheseparatingmedium,leadingtotheproblemofdewatering.Onlypyriticsulfurcanberemovedwithphysicalbeneficiationandpyriteremovalcausescertainlossincombustiblematter.Gravitybeneficiationforcoalusuallyrequiresfeedsizelargerthan0.5mm.Physicalseparationisnotsuitableforchemicallyboundminerals3.成灰矿物质通常嵌布在煤的结构中，尽管物理洗选对于工业来讲可能是比较简单的方法，但采用物理方法进行煤炭洗选还是比较困难的。煤的物理洗选方法有以下方面的局限性：细磨需要释放出细粒黄铁矿包裹体。细磨属于能量密集型操作，而且超细粒的处理和脱水比较困难。增加脱硫需要研磨较细的粒度，但是会降低分选介质的密度，导致脱水困难。物理分选方法只能脱除黄铁矿硫，而且硫的脱除会对可燃物质造成一定的损失。重力选煤通常需要入料粒度大于0.5mm，物理分选方法不适合化学结合的矿物。4.Frothflotationisseparationofmineralsthatdiffergreatlyinwettabilitybyusingasurfaceactiveagentwhichcanstabilizeafrothformedonthesurfaceofanagitatedsuspensionofthesubstanceinwater.Primarily,theashandsulfur-bearingmineralsfoundincoalarehydrophilic,andthereforeshouldremaininthetailingsduringtheprocessofflotation.Generally,frothflotationisthetechniqueusedforthebeneficiationofcoalparticlesbelow0.5mminsize.Thecarbonaceousmineralconstituentsofcoalbeinghydrophobicinnature,canbemadetopreferentiallyattachtofinebubblesandfloattothesurfaceofadiluteslurry,wheretheycanberemoved,whileincontrastthelowcarbonaceousinertmineralsoftherawcoaldonotattachtothebubbles4.泡沫浮选是一种通过表面活性剂在水中搅拌悬浮液的物质表面形成稳定的泡沫，从而分选出表面润湿性有很大不同的矿物分选方法。煤中的灰分和含硫矿物主要是亲水性的，因此在浮选过程中会留在尾矿里。泡沫浮选方法一般用于分选粒度小于0.5mm的煤颗粒。煤中的碳质矿物成分具有天然疏水性，可以优先吸附到细小的气泡上从而上浮到表面的泡沫层被分离出来，而相比之下原煤中低碳惰性矿物不会吸附到泡沫上。5.Typically,oxyhydrylcollectorsareorganicacids,orsoaps.Thecarboxylatesareknownasfattyacids,andoccurnaturallyinvegetableoilsandanimalfatsfromwhichtheyareextractedbydistillationandcrystallization.Thesaltsofoleicacid,suchassodiumoleateandlinoleicacid,arecommonlyused.Aswithallioniccollectors,thelongerthehydrocarbonchainlength,themorepowerfulisthewater-repulsionproduced,butsolubilitydecreases.Soaps(thesaltsoffattyacids),however,aresolubleevenifthechainlengthislong.Thecarboxylatesarestrongcollectors,buthaverelativelylowselectivity.Theyareusedfortheflotationofmineralsofcalcium,barium,strontium,andmagnesium,thecarbonatesofnon-ferrousmetals,andthesolublesaltsofalkalimetalsandalkalineearthmetals.5.通常，氢氧捕收剂是有机酸或脂肪酸盐。众所周知羧酸盐属于脂肪酸，天然存在于植物油和动物脂肪中，可以通过蒸馏和结晶的方法提取出来。油酸盐中，油酸钠和亚油酸是最常用的。所有的离子型捕收剂中，随着烃链增长，产生的水斥力也增强，但是溶解度会降低。然而肥皂（脂肪酸盐），即使烃链长度较长也是可溶的。羧酸盐是强捕收剂，但是选择性相对较低。它们用来浮选钙，钡，锶，镁，有色金属碳酸盐，碱金属和碱土金属的可溶性盐。（答案必须写在试卷上，试题和试卷一起交回）