1、Small-ScaleManufactureofBurnedBuildingBrickPerhapsthemostimportantfactorindryingisthehackor11jannerinwhichthebrickshapesarestackedinthedryingarea.InillustrationNo.3,righthanddrawing,Isshownatypicalhack,fordryingbrick.Inthisoperation,twobrickarefirstplacedonthegroundonthefaceornarrowdimension.Theyare
2、placed-f-,.brickmoldandthe-resultantproductwi11thenbeirregu-Iarandjagged.OncetheproperConsisterlcyorwater-clayratioisdeterminedexperimentally,thepitoperatorshouldexerciseallpossiblecaretoseethatthisconsistencyismaintainedthroughouttheworkingday.Afterexcessclayisremoved,thenioldmaybeliftedupandfreeof
3、thebrickcastings.Inordertogetastraightupdrawoftheno1d,itisnecessarytohavetwomenperformtheoperation.Oncefreeofthebrick,themoldisagainwettedwithwaterandsandissprinkledontheinnersurfaces.Itisthenplacedonthegroundinfrontofthebrickjustreleasedfromthemold.Thus,thebrickmakingprocessbecomesacontinuousoperat
4、ionwiththemoldmovingprogressivelytomakerowafterrowofbrick.SeeIllustrationNo.2.3.BrickDryingInaridcountries,itisnotgenerallynecessarytocoverthenewlymadebrick.Theyaresimplyleftinlhepositioninwhichtheyweremadeanda11owedtodryinthesun.Inthoseareaswhererainfallisadailyoccurrence,itisbesttoprovideacovering
5、forthenewlyformedbrick.Thecovershouldhavenosidessothattheaircanmovefree1yaroundthebrick.Afteraboutthreedaysintheflatorasmadeposition,thebrickcanbehandledwithoutdeformingorcrumb1ing.Althisstage,theyareplacedinaspecialmannertospeedupthefinalstagesofdrying,asfarapartasabrickislong.Then,at$Wtotnefirsttw
6、obrick,twomorebrickareplacedonthetopofthefirsttwo.Thesecondplacedbrickwillcovertheendsofthefirstpair.InordertoestablishsomedegreeofstabilityinsuchanopensettingofbrickasthepiIeextendshigher,itisrecommendedthatatiebrickbeusedtokeepthestacksofbrickfromtoppling.Thetiebrickactuallykeysoneverticalcolumnof
7、brickintotheoneadjoiningit.Thekey,ortie,brickisplacedsothatitextendsfromthecenterofthefirsttwobrickmentionedabovetothecenterofthepairofbrickplacedadjacenttoit.Theconti:iuedplacingofpaironpair,90reversalasthepileextendsupward,-5-i/,.iandthealternatetie-brickplacementcontinuesunti1thedryingstackisabou
8、tfivefeethighandofanyconvenientlength,generallyabout10feet.Dryingisaccomplishedbypermittingprevai1ingwindstocirculatethroughtheopenspacesoftheI,hack.Threeimportantfactorscontroltherateofdrying:t11theheatnaturalIyavailable,(2)thehumidity,and3theamountoffineparticlesintheclay.Obviously,idealconditicns
9、wouldcallforalocalewhereintheheatofthedaywouldstayquitehighwiththesunshin-ingmostofthetime.Secondly,thelowerthehumidity,themorerapidthedryingofthebrick.Thepresenceofextremefinesorverypowderyclaywillrequiremorewaterintheclay-watermixturetoform.sthesamefinesintheclayaremorereluctanttogiveuptheformingw
10、ater,thedryingtimewillthusbeextended.Asandyclayismoreapttodryrapidly,witnoutcracks,thanaclaywhichispredominantlyfines.Thebrickmakermayfindthattheclayheisusinghasapreponderanceofextrcmc1yfineparticleswhichcausesbrickcracking.Hecancorrectthisfaultbyaddingsomesandymaterialtotheclaymix,Theparticlesofsan
11、dshouldbethesizeofgrainsofsaltwithafewaslargeasmatchheads.Inanyevent,itisnecessarytoprovideatleastoneful1weektoinsurecompletedrying.Duringthistime,thepossibilityofrainfallmustbe,takenintoaccount.Ifthestackofbrick,asdescribedabove,isstandinginanunprotectedareaandisexposedtotherain,itisentirelyp.ossib
12、lethatthebrickwilllosestrengthuponbeingwettedandwillslakeorcrumbleasaresultofthenewlycombinedwater.Boththetopofthebrickstandandthebasemustbeadequatelyprotected.Topprotectiondesignedtoshedordinaryrainfal1isaccomplishedbyplacingafewcutsoflig3tweightcorru-gatedmetalonthetopofthebrick.Thisisdemonstrsta,
13、1inIllustrationNo.3,lefthanddrawing.Duringarain-fal1,itispossiblethatrun-offwaterorpoolsmaydeveloparoundthebottomcourseofbrick.Inordertoprotectthestackfrombecomingweakenedduetoawatersofteningofthisbottomcourse,itisrecommendedthatthedryingstackbebuiItuponafirstcourseofpreviouslyburnedbrick.Thesebrick
14、areresistanttowaterslakingandwillremainrigidalthoughwetfromwaterrun-off.1.ocalconditions,includingthehumidity,theper-sistenceofrain,theamountofsolarexposure,themotionofhotaircausedbywind,aswcl1asthenatureofthe6clayitself,wi11dictate,toalargedegree,whenthedryingprocessiscompleted.Inanyeven,t,:,it:isi
15、m-pcrativethatthedryingprocessbecompletebeforethebrickaretakentothefinalprocess:thefiringorburningofthebrick.Therearetwosimpleteststodetermineifthe,dry-ingprocessis,indeed,complete.Asclaydries;itchangescolor.Generallythecolorbecomes1ighterasthewaterleavestheclaymass.Thus,athoroughlydriedbrickwouldsh
16、ownocolordifferentia,upon1beingbrokeninha1f,fromtheouterskinareaor-thecentersectioninsidethebrick.Anothermeansofdeterminingifal1thedryingiscompleted,istoweighabricktakenfromthedryinghack.Thenplace-itinanovenornearasourceofheat.Weighagain.Ifthebrickheatedintheovenshowsalossofweight,thismeansthatthebr
17、ickinthedryingpiIealsomustcontainwaterandthusthedryingprocessis.notcomplete.4.KilnConstructionandBrickFiring11isinthefiringofthebrickthatitreceivesitsstrength.Inthepreservofhighheat,thealkalicsintheclay,togetherwithSmaIlamountsofoxidesofironandothermetalsarejoined,toadegree,inchemicalunionwiththealu
18、minaandsilicaintheclaytoformadenseanddurablemass.kiInisa,furnaceoroveninwhichbrickarefiredorhcmreatedtodevelophardness.Wherebrickmakingisdoneonalargescale,thefiringoperationisperformedinacontinuous-processkilnre-ferredtoas.atunnelkiln.Inmakingbrickonasmallscale,firingisaperiodicoperationwhereinthebr
19、ickareplacedinthekiln,thefirestartedandheatdeveloped,andthen,afterseveraldaysoffiring,thefueliscutofffromlhefireandtheentirekilnanditsloadarcallowedtocooldownnaturally.Wherebrickmakingisonahighproductionbasis,theki11isthelargestsingleinvestmentforthe,manufacturer.Itcanrepresentacostofasmuchasahalfmi
20、lliondollars.Forourpurposes,wewillconcernourselveswiththeperiodic-typekiIn.Wewilllimitourattentiontokilnswhichcanbebuiltoflocallyavai!ablematerialandcanbefiredwithfuelsnativetotheland.Toreducethekilntoitssimplestparts,wewillidentifythedifferentcomponentsasfollows:.TheFireBox,TheFlueSystem,ThePermane
21、ntSideWallsandtheMuddcdEndWalls7Thefireboxisanopeningthroughwhichtheoperatorfeedsthefuel.Itgenerallyconsistsofanopeningabout24incheswideand38incheshighand30inchesdeep.Thetopareacanbearch-shaped,butthisisarefinementwhichisnotnecessary.24-inchspan,Inthecenteroftheabout20inchesfromtheground,ironrodsorg
22、ridbarsareplaced,indiameter,Thesebars,preferably3/4inchesarespacedabout3inchesapartandaretoserveasagrateintheopeningoflhefirebox.Theyaresecuredbyembeddingtheminthebrickworkoneithersideoftheopening.SeedetailinIllustrationNo.4.madeThefluesystemisthesystemofopenspacespurposelyinstackingthebricktoallowt
23、hemovementofheatandgases.Thefluesystemprovidesopeningsfortheheatfromthefireboxtoreachthebrickinthekilnandtotraveltotheupperareasofthekilninthesamemannerassmokeandheatwilltravelupachimney.Thefluesystemis,then,achimneybuiltinthekiInofthebricktobeburned.Thepermanentsidewallsaremadeofpreviouslyfiredbric
24、kwhichformthetwosidesofthekiIn.Thefireboxesarelocatedinthepermanentsidewalls.Bothsidewallsareidentical.Theyaregenerallyabout10feetapartandareperfectlypara!lei.Thebricktobefiredareplacedintheareabetweenthepermanentsidewalls.Per-manentsidewalIsarenormallytwobricklengthsor20inchesthick.SeeIllustrationN
25、o.5.Tothoseconfrontedwiththetaskofbuildingsuchakiln,thethoughtmayoccur,JustwheredoIgetbricktomakethesidewallsandthefireboxes?Theanswerissimple.Onewou1dstartwithgreenorunfiredbrickandmaketheentirekiln,sidewallsandfirebox.Thefirstkilnwou1dbegreatlyreducedfromthesizeoftheprojectedkiIn.Afterthefirstfiri
26、ng,perhapsasmanyas50%ofthebrickinthekilnwilldeve1openoughhardnesstobeused.Thesearesetasideandcontinuedfir-ingswiththeSmaIlscalekilnaremadeunti1sufficientbricktomakethetwofuil-sizedsidewalIsareaccumulated.TheMuddedEndWallsareclosuresofbrickwhichareconstructedattheendsofthepermanentsidewalls.ThemuddedEndWallsmaybemadeOf-PreViOUSIyburnedbrickortheymaybebuiltupofunburnedbrick.ItisthroughtheopeningsclosedbytheMuddedEndWallsthatthebrickareloadedintothekilnandremovedfromthekiln,s-8-I38INCU95r一
