制鹽工藝流程

鹽田飽和鹵水直接進(jìn)蒸發(fā)罐真空制鹽工藝介紹靳志玲（中鹽制鹽工程技術(shù)研究院，天津300450）內(nèi)容摘要：利用灘田飽和鹵水直接進(jìn)蒸發(fā)罐蒸發(fā)結(jié)晶制取氯化鈉，在制鹽過程中采取三次洗滌方法，除去鈣鎂離子，以獲得純度超過99.1%的氯化鈉和濃度較高的制鹽母液。關(guān)鍵詞：灘田飽和鹵水真空精制鹽1簡介目前，國內(nèi)大部分井礦鹽企業(yè)采用以井礦鹽鹵為原料，北方部分生產(chǎn)企業(yè)采用原鹽化成飽和鹽水再精制真空鹽的生產(chǎn)方法。隨著國內(nèi)“兩堿”的迅速發(fā)展和人民生活水平的提高，原鹽供需矛盾已越來越突出。特別是在海鹽區(qū)，以原鹽溶解成飽和鹵水再生產(chǎn)精制鹽，不僅增加了原鹽的消耗，而且降低了鹽田面積的使用效率，增加投資，生產(chǎn)成本高，不同程度上影響了食用鹽生產(chǎn)企業(yè)的經(jīng)濟(jì)效益，造成許多食用鹽定點(diǎn)生產(chǎn)企業(yè)減產(chǎn)、虧損，直接影響了百姓的生活。而采用灘田飽和鹵水直接進(jìn)蒸發(fā)罐制鹽，即可以節(jié)約結(jié)晶面積，其母液還可以為生產(chǎn)氯化鉀、氯化鎂等鹽化工產(chǎn)品提供高質(zhì)量原料苦鹵，達(dá)到充分利用鹵水中的各種有效成分，實(shí)現(xiàn)零排放、無污染、循環(huán)經(jīng)濟(jì)的目的。工藝流程簡述鹵水經(jīng)灘田日曬蒸發(fā)，至飽和后引入一個(gè)鹵水庫中儲存。鹵水庫的作用，一是儲存一定量的飽和鹵水，以備真空制鹽生產(chǎn)的需要；二是鹵水在此有一定的停留時(shí)間，可以使其中的一些雜質(zhì)顆粒沉淀下來，達(dá)到凈化鹵水的目的。凈化后的飽和鹵水從鹵水庫引出后，進(jìn)入蒸發(fā)制鹽車間的精鹵桶。采用預(yù)熱后的鹵水進(jìn)罐，順流轉(zhuǎn)料、末效排鹽漿，集中排母液的方式進(jìn)行生產(chǎn)。I效蒸發(fā)罐鹽箱中的鹽排到II效下循環(huán)管中，II效鹽箱中的鹽排到III效下循環(huán)管中，III效鹽箱中的鹽排到IV效下循環(huán)管中，最后集中在IV效鹽箱；IV效排出鹽漿，同時(shí)由IV效分離罐排出母液。工藝流程簡圖見圖1。

生蒸汽原料鹵水閃發(fā)汽I效二次蒸汽I效蒸發(fā)罐閃發(fā)汽II效二次蒸汽 III效二次蒸汽II效蒸發(fā)罐4.III效蒸發(fā)罐IAw效二次蒸汽^母液不凝汽去真空泵混合冷凝器r冷卻水冷卻水回鍋爐

冷凝水I效閃發(fā)桶I效平衡桶冷凝水II冷凝水□效閃發(fā)桶皿效平衡桶皿效閃發(fā)桶

W平橫桶冷凝水一預(yù)熱器原料鹵水生蒸汽原料鹵水閃發(fā)汽I效二次蒸汽I效蒸發(fā)罐閃發(fā)汽II效二次蒸汽 III效二次蒸汽II效蒸發(fā)罐4.III效蒸發(fā)罐IAw效二次蒸汽^母液不凝汽去真空泵混合冷凝器r冷卻水冷卻水回鍋爐

冷凝水I效閃發(fā)桶I效平衡桶冷凝水II冷凝水□效閃發(fā)桶皿效平衡桶皿效閃發(fā)桶

W平橫桶冷凝水一預(yù)熱器原料鹵水生活用水 ?預(yù)熱器冷凝水冷凝水原料鹵水冷凝水冷凝水鹽漿工藝的優(yōu)缺點(diǎn)運(yùn)用該工藝已在中國北方建設(shè)了一個(gè)年產(chǎn)15萬噸的真空制鹽生產(chǎn)線，相比再制鹽生產(chǎn)工藝，其實(shí)施效果如下：本工藝采用飽和鹵水制鹽，不需要淡水化原鹽，淡水消耗低，可節(jié)約淡水資源，根據(jù)生產(chǎn)情況，1t鹽消耗淡水1.4-0.2m3，而再制鹽生產(chǎn)工藝需要淡水3.5-4.53.73m3，噸鹽節(jié)約了2.1-4.3m3淡水。2） 節(jié)約日曬鹽場土地，減少原鹽消耗，提高了鹽田利用率對再制鹽生產(chǎn)線來說，一般生產(chǎn)It精制鹽需要消耗1.2t日曬原鹽，年產(chǎn)15萬t的精制鹽需要18萬t原鹽，需要結(jié)晶面積136.36公頃（按目前中國北方鹽場有效結(jié)晶單產(chǎn)16501/公頃，有效面積占80%）,采用飽和鹵水直接進(jìn)蒸發(fā)罐工藝，不需要飽和鹵水進(jìn)結(jié)晶池繼續(xù)蒸發(fā)制鹽，只需要建設(shè)一個(gè)約2公頃的飽和鹵庫，因此，節(jié)約了土地面積134.36公頃，節(jié)省的結(jié)晶面積可用于增加日曬鹽產(chǎn)量85471，按日曬鹽銷售價(jià)160元/t計(jì)算，日曬鹽增加產(chǎn)值136.8萬元。如果土地按3萬元/畝計(jì)算，節(jié)約土地價(jià)值為6000多萬元。3） 采用三次洗滌方法洗滌鹽漿以去除鈣鎂離子，使氯化鈉含量超過99.4%，精制鹽達(dá)到優(yōu)級鹽質(zhì)量。蒸發(fā)結(jié)晶過程中鹽漿會夾帶大量的母液，母液中含有大量的鈣、鎂雜質(zhì)，因此，采用三次不同的洗滌方式洗滌鹽漿，提高精制鹽質(zhì)量。4）用飽和鹵水直接生產(chǎn)精制鹽母液損失小，提高了母液的利用率，實(shí)現(xiàn)鹽化聯(lián)產(chǎn)采用鹽田飽和鹵水直接生產(chǎn)優(yōu)級真空精制鹽工藝，每產(chǎn)1t精制鹽副產(chǎn)母液約1.7m3，以年產(chǎn)15萬t精制鹽計(jì)算，全年可產(chǎn)生25.5萬m3蒸發(fā)母液，且排出的苦鹵氯化鉀含量達(dá)到了24?30g/l,濃度為29?34°Be',鈉鎂比值為1.4?0.6,排出的苦鹵中氯化鉀總含量為6589t，氯化鎂總量為36540t，硫酸鎂總量為18900t，氯化鈉總量為37600t,溴總量510t。而年產(chǎn)18萬t原鹽，排出的苦鹵量一般只有18萬m3,經(jīng)過復(fù)曬、滲透損失、溝道輸送進(jìn)入化工廠后只有原來的45%左右，也就是說還有8.1萬m3，這時(shí)氯化鉀總含量為2036t，氯化鎂總量為15280t,硫酸鎂總量為7727.4t,氯化鈉總量為11128t,溴總量162t。因此，該工藝可為鹽化工生產(chǎn)提供更多的原料，提高了生產(chǎn)效率，降低了各種消耗，節(jié)約能源。該工藝排出的制鹽蒸發(fā)母液溫度在55.04°C以上，可通過管道直接進(jìn)入下步生產(chǎn)氯化鉀的工序，生產(chǎn)氯化鉀產(chǎn)品，節(jié)約氯化鉀生產(chǎn)過程中所需熱量，折標(biāo)煤1157噸/年5） 由于灘田飽和鹵水較化鹽鹵水氯化鈉含量低，因此單位產(chǎn)品的蒸發(fā)水量較高，噸鹽產(chǎn)品電、蒸汽消耗量較大，能耗較高。6） 蒸發(fā)設(shè)備換熱面積較化鹽溶解工藝稍高，因此設(shè)備投資相對較高，但由于節(jié)省大量鹽田結(jié)晶面積，總體投資低。與原鹽溶解再制鹽工藝技術(shù)經(jīng)濟(jì)指標(biāo)比較國內(nèi)海鹽區(qū)生產(chǎn)真空鹽的工藝主要有灘田飽和鹵水進(jìn)罐蒸發(fā)制鹽和原鹽溶解制成飽和鹵水蒸發(fā)制鹽兩種方法。原鹽溶解制成飽和鹵水蒸發(fā)制鹽工藝優(yōu)缺點(diǎn)有：（1）需建結(jié)晶池，工程總體投資較高；（2）單位產(chǎn)品蒸發(fā)水量小，設(shè)備投資稍低，（3）噸鹽消耗電、蒸汽量較?。唬?）水消耗較大，噸鹽產(chǎn)品耗水2.4m3，（5）蒸發(fā)母液損失大。比較兩種制鹽方法技術(shù)經(jīng)濟(jì)指標(biāo)如表。表主要經(jīng)濟(jì)技術(shù)指標(biāo)比較項(xiàng)目再制鹽生產(chǎn)飽和鹵水直接進(jìn)罐生產(chǎn)投資：結(jié)晶池投資550萬元0蒸發(fā)設(shè)備投資9701080單位產(chǎn)品投資335元/噸306元/噸消耗指標(biāo)：原煤0.23噸0.21噸原鹽1.25噸一1.15噸0.00噸鹵水0.007.5m3白水3.545m31.4-0.2m3電50-70度50-70度兩種工藝在投資和單位產(chǎn)品生產(chǎn)成本中有較大的差別，飽和鹵水法單位產(chǎn)品總投資低于原鹽溶解法，單位產(chǎn)品成本低于原鹽溶解法30％。5.結(jié)論對于北方海鹽區(qū)生產(chǎn)精制鹽企業(yè)來說，利用灘田飽和鹵水直接進(jìn)蒸發(fā)罐制取精制鹽是一個(gè)較好的生產(chǎn)工藝，節(jié)約投資，節(jié)約土地，特別是將寶貴的原鹽溶解成飽和鹵水再進(jìn)行制鹽是對土地資源的浪費(fèi)，再有其生產(chǎn)成本低，企業(yè)有較高的利潤空間；排出的制鹽母液綜合利用生產(chǎn)鉀、溴、鎂等產(chǎn)品，使鹵水全部吃干榨凈，沒有廢物排放，減少了環(huán)境污染，有利于可持續(xù)發(fā)展。Newtechnologyofproducingrefinedsaltbyaddingsaltfield

saturatedbrineintoevaporatordirectlyJinzhilingGeJinyang(SaltResearchInstituteChinaNaturalSaltIndustryCorporation,TianJin300450)Abstract:AfterMakingsalinesaturatedbrineflowinevaporatingpot,thesodiumchlorideisobtainedbyevaporativecrystallization.Calciumandmagnesiumionscanberemovedbywashingsaltthreetimesinordertogetthesodiumchloridethatthepurityisover99.1percentandthemotherliquorthathavehighconcentration.Keywords:salinesaturatedbrine,vacuum,refinesaltmagnesiumchlorideetc.inorderto1BRIEFINTRODUCTION makeuseofallkindsofeffectiveAtpresent,thematerialsofmakingvacuumsaltareusingthewellandrocksaltinmostofthewellandrocksaltcorporationsandthesaturatedbrinegotbydissolvingcrudesalt.Alongwiththerapiddevelopmentofcausticalkaliandsodiumcarbonateandthegrowthinthepeople'slivingstandard,thecontradictionofcrudesaltinsupplyandrequireismoreandmorestoodout.Particularlyintheseasaltareas,productingrefinesaltwithsaturatedbrinethatisgotbydissolvingcrudesaltcanincreasetheconsumptionofrawsalt,reducetheavailabilityfactorofsaltfield,addinvestmentandproductioncost.Thiswillinfluencetheeconomicefficiencyofediblesaltmanufacturingenterprises,makethemreduceoutputandaffectpeople'slive.However,usingthemethodofmakingsalinesaturatedbrineflowinevaporatingpotandthenobtainingsodiumchloridebyevaporativecrystallizationcansavingcrystalarea.Furthermore,themotherliquorcanbeusedasmaterialtoproducechemicallyproductssuchaspotassiumchloride,constituentsinthebrineandachievetheobjectsofnodischarge,nopollutionandcirculatingeconomy.2.INDICATIONOFTHEPROCESSFLOWAfterbeingsolarizedtosaturationinbeachfieldbrinewasinductedtobrinetankandstored.Ontheonehandbrinetankcanstoresomesaturatedbrinethatisusedtoproducevacuumsalt.Ontheotherhand,brinehavesomeresidencetimeheresosomeimpuritiescanbedepositedinordertomakethebrinebepurified.Afterbeingdrawoutedfrombrinetankthecleanedsaturatedbrinewaspumpedtofinebrinetankinthemanufacturesaltplant.Andproductioncanbegoneonbyusingthemethodsofpreheatingbrine,transferringstuffinparallelflow,dischargingsaltslurryinthelasteffectandexportingmotherliquorconcentratedly.Thesaltinthefirsteffecttankisdischargedtothecirculationpipeofthesecondeffect,Thesaltinthesecondeffecttankisdischargedtothecirculationpipeofthethirdeffect,Thesaltinthethirdeffecttankisdischarged fourtheffecttankwherethesaltslurrytothecirculationpipeofthefourthandthemotherliquoraredischarged.effect.Atlastthesaltiscollectedinthe Fig.1isthediagramoftheprocessflow.生蒸汽原料鹵水閃發(fā)汽I效二次蒸汽I效蒸發(fā)罐鹽II效一次烝汽III效二次蒸汽 W效二次蒸汽II不凝汽去真空泵回鍋爐

冷凝水I效閃發(fā)桶I效平衡桶冷凝水預(yù)熱器冷凝水閃發(fā)汽II冷凝水冷凝水原料鹵水III效蒸發(fā)罐W臓閃發(fā)汽W效蒸發(fā)罐混合冷凝器生蒸汽原料鹵水閃發(fā)汽I效二次蒸汽I效蒸發(fā)罐鹽II效一次烝汽III效二次蒸汽 W效二次蒸汽II不凝汽去真空泵回鍋爐

冷凝水I效閃發(fā)桶I效平衡桶冷凝水預(yù)熱器冷凝水閃發(fā)汽II冷凝水冷凝水原料鹵水III效蒸發(fā)罐W臓閃發(fā)汽W效蒸發(fā)罐混合冷凝器冷卻水冷卻水 4原料鹵水□效閃發(fā)桶皿效平衡桶皿效閃發(fā)桶

W平橫桶冷凝水一冷凝水冷凝水+鹽漿預(yù)熱器生活用水 >Figure.1Diagramoftheprocessflow3.RELATIVEMERITSOFTHEPROCESSInthenorthofChinaaproductionlinehasbeenbuiltwiththisprocess,whichcanproduce1.5milliontonssaltperyear.Comparingwithreworksaltproductionprocess,theeffectofthisprocessisasfollows:Thesaturatedbrineisusedinthisprocesstaketheplaceofdissolvingcrudesaltwithfreshwater.Suchcanreducetheconsumptionoffreshwaterandsavetheresource.Accordingtotheproduceconditions,producing1tonsaltwillconsume1.4-0.2m3freshwater.Andthatifusethereworkingsaltprocess3.5-4.53m3freshwaterwillbeused.Thatistosay2.1-4.3m3freshwatercanbesavedcorrespondingto1tonsalt.Savingthesolarsaltfield,reducetheconsumptionofcrudesalt,increasetheavailabilityofthesaltfield.Forthereworkingsaltproductionline,asageneralruleproducing1tonrefinesaltwillconsume1.2tonssolarsalt.Producing1.5milliontonrefinesaltneeds1.8milliontonscrudesaltand136.36hectarecrystalarea(Accordingtotheexperiencethatonehectarecanproduce1650toncrystalandtheeffectiveareais80percent).Usingtheprocessthatthesaturatedbrineispumpedtoevaporatingtankdirectlythebrineneednotevaporateincrystalpondbutforasaturatedbrinestoreroomofabout2hectare.Suchcansavesurfaceareaof134.36hectareandthisareacanbeusedtoincrease8547tonoutputofsolarsalt.Hencetheproductivevalueofsolarsaltwillincrease136.8tenthousandyuanaccordingtothemarketpriceofsolarsaltwhichis160yuan/t.Andlandvalueof60millionyuancanbesavedifthelandis30,000yuanpermou.Adoptingthemethodofwashingsaltthreetimesinordertogetridofcalciumandmagnesiumions,makethepurityofsodiumchlorideexceed99.4%andmaketherefinesaltreachfirstquality.Intheprocessofevaporativecrystallizationmuchmotherliquorwillexistinsaltslurry.Themotherliquorcontainsalotofimpurityofcalciumandmagnesium.Sosaltslurryiswashedinthreedifferentwaysinordertoimprovethequalityofrefinesalt.Usingthesaturatedbrinetoproducerefinesaltcanreducetheconsumeofmotherliquors,enhanceit'savailabilityandrealizetheproductionofsaltandchemicalstogether.Theprocessthatproducingexcellentvacuumsaltwithsalinasaturatedbrinedirectlycanget1.7m3motherliquorinrelationto1trefinesalt.Onthebaseof150,000tonrefinesalt,wecanget255,000m3evaporationmotherliquor.Inbitterbrinewhoseconcentrationis29?340Be'thecontentofpotassiumchlorideis24?30g/landtheratioofsodiumandmagnesiumis1.4?0.6.And6589tpotassiumchloride,36540tmagnesiumchloride,18900tmagnesiumsulfate,37600tsodiumchlorideand510tbrominearecontainedinthebitterbrine.Thebitterbrineisabout180,000m3inrelationto180,000tcrudesalt.Afterbeingsolarizedrepeatedlyandconsumingforfilterthebrineisleft45%whenitispumpedtochemicalplant.Thatistosaythereare81,000m3brine.Bynowthereare2036tpotassiumchloride,15280tmagnesiumchloride,7727.4tmagnesiumsulfate,11128tsodiumchlorideand162tbromine.Sotheprocesscanprovidemorematerialforsaltandchemicalsplants,heightenproductionefficiency,reduceallkindsofconsumptionandsaveenergy.Thetemperatureofthemotherliquorgotfromthisprocessisover55.04°C.Soitcanbepumpedtothepotassiumchlorideprocesswithpipetoproducepotassiumchloride.Suchwillsavetheheatquantityintheprocessofproducingpotassiumchloride.Andtheheatquantityisequalto11578t/ystandardcoal.Becausethecontentofsodiumchlorideinthebeachsaturatedbrineislowerthanthecontentinthebrinethatisgotbydissolvingsalt,theevaporatedwaterofunitproduceishigher,theelectricityandsteamconsumptionaremore.Thatistosaytheenergyconsumptionishigher.Theheatexchangeareaisalittlerbiggerthantheprocessofdissolvingsalt,sotheequipmentinvestmentishigher.Butbecauseofsavingalotofsalinacrystalareathetotalinvestmentislower.4.COMPARETHEECONOMICINDICATORSWITHTHEPROCESSOFDISSOLVINGCRUDESALTANDTHENREMAKINGSALTInChinaTherearetwomainmethodstoproducingvacuumsaltinseasaltarea.Oneispumpingthebeachsaturatedbrineintoevaporatingpot.Theotherisusingthesaturatedbrinegotbydissolvingcrudesalt.Comparingthesecondmethodwiththefirstmethodthe

relativemeritsofthesecondmethodisasfollows(:1)needtobuildcrystalpondandthetotalinvestmentishigher.(2)Theevaporatedwaterofunitproductissmallerandtheequipmentinvestmentislower.(3)Theconsumingofelectricityandsteamislower.(4)Theconsumingofwaterismoreand2.4m3waterwillbeconsumedinrelationto1tonsalt.(5)Thelossofmotherliquorisbigger.Theeconomicindicatorsofthetwomethodsareasfollows:ComparisonofthemaineconomicandtechnicalnormsItemTheprocessbydissol