《湿法冶金过程及设备培训》-萃取的原理及过程重难点答疑

萃取的原理及过程重难点答疑Q&AonKeyandDifficultQuestionsinthePrincipleandProcessofExtraction一、常见重点问题答疑I.AnswerstoFrequentlyAskedKeyQuestions1.问题：什么是萃取（液液萃取）？请简述其核心原理。1.Question:Whatisextraction(liquid-liquidextraction)?Pleasebrieflydescribeitscoreprinciples.答案：萃取（液液萃取）是指两个完全不互溶或部分互溶的液相接触后，一个液相中的溶质经物理或化学作用转移到另一个液相，或在两相中重新分配的过程。其核心原理是利用溶质在两种互不相溶（或部分互溶）的液相中具有不同的溶解度（或分配比），从而实现溶质的分离或富集。Answer:Extraction(liquid-liquidextraction)referstotheprocessinwhichtwocompletelyimmiscibleorpartiallymiscibleliquidphasescomeintocontact,andthesoluteinoneliquidphaseistransferredtotheotherliquidphasethroughphysicalorchemicalaction,orredistributedinthetwophases.Itscoreprincipleistousesolutestohavedifferentsolubilities(ordistributionratios)intwomutuallyinmiscible(orpartiallymiscible)liquidphases,soastorealizetheseparationorenrichmentofsolutes.2.问题：萃取过程中的核心术语“分配比”“萃取率”分别指什么？2.Question:Whatdothecoreterms"distributionratio"and"extractionrate"intheextractionprocessreferto?答案：Answer:分配比：指平衡时溶质在萃取相总浓度与萃余相总浓度之比，反映了溶质在两相中的分配情况。Distributionratio:Referstotheratioofthetotalconcentrationofsoluteintheextractionphasetothetotalconcentrationofraffinatephaseatequilibrium,whichreflectsthedistributionofsoluteinthetwophases.萃取率：指萃入萃取相的溶质占原始总量的百分比，用于衡量萃取过程对溶质的提取效率。Extractionrate:Referstothepercentageofsoluteextractedintotheextractionphasetotheoriginaltotalamount,whichisusedtomeasuretheextractionefficiencyofsoluteduringtheextractionprocess.3.问题：萃取剂的选取需要满足哪些基本要求？3.Question:Whatbasicrequirementsneedtobemetfortheselectionofextractant?答案：萃取剂的选取要求包括：选择性好（对目标溶质溶解能力强，对其他物质溶解能力弱）；萃取容量大（能溶解较多目标溶质）；化学稳定性好（不易分解、变质）；分相好（与原液相易分离）；易于反萃取或精馏分离；操作安全经济且毒性小等。Answer:Theselectionrequirementsofextractantinclude:Goodselectivity(strongsolubilityfortargetsolute,weaksolubilityforothersubstances);largeextractioncapacity(candissolvemoretargetsolutes);goodchemicalstability(noteasytodecomposeanddeteriorate);goodphaseseparation(easytoseparatefromtheoriginalliquidphase);easyreextractionorrectificationseparation;safeandeconomicaltooperateandhavelowtoxicity.二、常见难点问题答疑II.AnswerstoFrequentlyAskedDifficultQuestions1.问题：在某萃取过程中，溶质在萃取相中的总浓度为6g/L，在萃余相中的总浓度为2g/L，相比（萃取相体积与萃余相体积之比）为1:2。请计算该溶质的分配比和萃取率。1.Problem:Inacertainextractionprocess,thetotalconcentrationofsoluteintheextractionphaseis6g/L,andthetotalconcentrationintheraffinatephaseis2g/L.Theratio(theratioofthevolumeoftheextractionphasetothevolumeoftheraffinatephase)is1:2.Pleasecalculatethedistributionratioandextractionrateofthissolute.答案：Answer:分配比（D）=萃取相溶质总浓度/萃余相溶质总浓度=6g/L/2g/L=3。Distributionratio(D)=totalconcentrationofsoluteinextractionphase/totalconcentrationofsoluteinraffinatephase=6g/L/2g/L=3.设萃取相体积为V，则萃余相体积为2V。萃取相中的溶质总量=6g/L×V，原始溶质总量=萃取相溶质总量+萃余相溶质总量=6V+2×2V=10V。萃取率=（萃取相溶质总量/原始溶质总量）×100%=（6V/10V）×100%=60%。AssumingthatthevolumeoftheextractionphaseisV,thevolumeoftheraffinatephaseis2V.Totalsoluteintheextractionphase=6g/L×V,totaloriginalsolute=totalsoluteintheextractionphase+totalsoluteintheraffinatephase=6V+2×2V=10V.Extractionrate=(totalsoluteinextractionphase/totaloriginalsolute)×100%=(6V/10V)×100%=60%.2.问题：如何理解“分离系数”这一术语？若某萃取过程中，溶质A的分配比为5，溶质B的分配比为0.5，该分离系数说明了什么？2.Question:Howdoyouunderstandtheterm"separationcoefficient"?Ifinanextractionprocess,thedistributionratioofsoluteAis5andthedistributionratioofsoluteBis0.5,whatdoesthisseparationcoefficientmean?答案：Answer:分离系数是两种溶质分配比的比值（通常以易萃取溶质的分配比为分子），用于反映两种溶质的分离效率，分离系数越大，说明两种溶质越容易分离。Theseparationcoefficientistheratioofthedistributionratiosofthetwosolutes(usuallythedistributionratiooftheeasilyextractablesoluteisusedasthenumerator),whichisusedtoreflecttheseparationefficiencyofthetwosolutes.Thelargertheseparationcoefficient,theeasieritistoseparatethetwosolutes.该过程中分离系数=溶质A的分配比/溶质B的分配比=5/0.5=10，说明溶质A比溶质B更容易被萃取，两者具有较好的分离效果。Inthisprocess,theseparationcoefficient=distributionratioofsoluteA/distributionratioofsoluteB=5/0.5=10,indicatingthatsoluteAiseasiertoextractthansoluteB,andbothhavebetterseparationeffects.3.问题：在湿法冶炼分离镍离子和钴离子的过程中，已知萃取剂X对镍离子的分配比为8，对钴离子的分配比为1；萃取剂Y对镍离子的分配比为6，对钴离子的分配比为0.5。从分离效果角度考虑，应选择哪种萃取剂？请结合术语说明理由。3.Problem:Intheprocessofseparatingnickelionsandcobaltionsbyhydrometallurgy,itisknownthatthedistributionratioofextractantXtonickelionsandcobaltionsis8and1;thedistributionratiooftheextractantYtonickelionsandcobaltionsis6and0.5respectively.Fromtheperspectiveofseparationeffect,whichextractantshouldbeselected?Pleaseexplainthereasonsinconjunctionwiththeterminology.答案：应选择萃取剂Y。理由：分离系数可反映两种离子的分离效率，分离系数越大，分离效果越好。萃取剂X的分离系数=镍离子分配比/钴离子分配比=8/1=8；萃取剂Y的分离系数=6/0.5=12。由于12＞8，萃取剂Y对镍离子和钴离子的分离系数更大，分离效果更优，因此应选择萃取剂Y。Answer:ExtractantYshouldbeselected.Reason:Theseparationcoefficientcanreflecttheseparationefficiencyofthetwoions.Thelargertheseparationcoefficient,thebettertheseparationeffect.SeparationcoefficientofextractantX=distributionratioo