► Yam dab tsi ntawm impurities accumulate li dross?
Ntau hom impurities tuaj yeem sau rau saum npoo ntawm cov hlau molten li dross:
◇ Hlau oxides - Oxygen reacts nrog cov hlau molten tsim cov khoom oxides.
◇ Fluxing agents - Cov khoom zoo li chlorides ua ke nrog oxides.
◇ Slag - Silicates thiab lwm cov tebchaw ntab los ntawm ore.
◇ Cov txheej qub - Cov xim, roj, roj, thiab lwm yam los ntawm cov hlau siv dua tshiab.
◇ Crucible hnav - Eroded ceramic hauv ob sab phlu.
◇ combustion residues - tshauv los ntawm cov cua sov fuels.
◇ Degassing agents - Ntxiv cov ntsiab lus xws li nitrogen lossis chlorine.
Dross skimming aims kom tshem tawm cov complex sib tov ntawm impurities ua ntej casting.
► Qhov muaj pes tsawg leeg ntawm dross sib txawv li cas?
Cov muaj pes tsawg leeg ntawm dross txawv heev nyob ntawm sebDross Skim Panhlau koom nrog thiab tshwj xeeb ntawm cov txheej txheem:
Aluminium Dross:
Aluminium dross feem ntau muaj qhov tseem ceeb ntawm cov hlau rov qab, nrog rau qee qhov sib xyaw ntau dua 30% ntawm cov khoom siv rov qab tau zoo.
Cov khoom tseem ceeb muaj xws li txhuas oxide, hlau txhuas, thiab lwm yam tsis yog xim hlau, xws li ntsev.
Zinc thiab Lead Dross:
Zinc dross zoo li zinc-nplua nuj, xav txog thawj cov hlau ua tiav, thaum cov hlau lead dross muaj cov ntsiab lus ntau dua.
Cov khoom sib xyaw ua ke ntawm cov zinc lossis txhuas oxides, cov khoom siv hlau, thiab cov impurities ntxiv uas tshwm sim los ntawm kev ua haujlwm tshwj xeeb.
Steelmaking Dross:
Steelmaking dross feem ntau yog tsim los ntawm cov hlau oxide tebchaw, feem ntau nyob rau hauv daim ntawv ntawm xeb thiab nplai.
Cov ntsiab lus ntxiv tuaj yeem tshwm sim, nyob ntawm seb cov hlau alloy muaj pes tsawg leeg thiab cov khoom siv hauv cov txheej txheem steelmaking.
Copper Dross:
Copper dross raug lees paub los ntawm kev txaus siab ntawm tooj liab oxide (CuO) cov tebchaw.
Cov khoom sib txawv tam sim no nyob rau hauv thawj qhov chaw tooj liab, xws li tin lossis npib tsib xee, tuaj yeem ntxiv rau kev tsim dav dav.
Cov yam ntxwv dav dav:
Drosses tuaj yeem sib txawv hauv daim ntawv ntawm lub cev, xws li los ntawm cov hmoov xoob mus rau cov khoom chunks los yog sib sau ua ke, nyob ntawm qhov kev ua haujlwm thiab cov hlau tshwj xeeb.
Lub hygroscopic xwm ntawm qee hom dross txhais tau hais tias lawv tau yooj yim nqus dej los ntawm ib puag ncig ib puag ncig, cuam tshuam rau lawv lub cev.
Cov dej noo:
Dross tuaj yeem muaj cov dej noo noo vim qhov hygroscopic ntawm qee cov khoom xyaw. Cov ntsiab lus noo noo tuaj yeem cuam tshuam rau kev tuav thiab ua haujlwm ntawm dross.
Fine Metal Droplets:
Dross feem ntau muaj entrained zoo hlau tee dej, sawv cev rau cov khoom tseem ceeb uas tuaj yeem raug tsom rau kev rov qab los ntawm kev sib cais.
Kev nkag siab txog kev muaj pes tsawg leeg pab qhia kev sib cais thiab kev kho kom rov zoo.
► Vim li cas nws tseem ceeb heev kom tshem tawm cov dej los ntawm cov hlau molten?
Tawm dross nyob rau hauv lubDross Skim Panmolten hlau muaj kev puas tsuaj rau cov khoom kawg:
Weaking ntawm Cast Hlau Structures:
Trapped gas pores nyob rau hauv dross tuaj yeem ua rau lub cev tsis muaj zog ntawm cov cam khwb cia hlau, cuam tshuam cov khoom siv ntawm cov khoom kawg.
Kev sib kis ntawm Alloying Elements thiab Chemistry:
Dross feem ntau muaj cov impurities uas tuaj yeem paug cov hlau molten, hloov cov hlau alloying thiab cov tshuaj muaj pes tsawg leeg. Qhov no tuaj yeem ua rau cov khoom tsis zoo thiab cuam tshuam cov khoom siv.
Qhov Teeb Meem Hluav Taws Xob thiab Pouring Nozzles:
Accumulated dross muaj peev xwm ua rau txhaws rauv kais dej thiab nchuav nozzles, cuam tshuam cov ndlwg ntawm cov hlau molten thiab impeding txheej txheem casting.
Defects thiab Roughness:
Kev suav nrog cov dej hauv cov hlau molten tuaj yeem ua rau muaj qhov tsis xws luag thiab roughness ntawm cov khoom tiav, txo qis nws txoj kev zoo nkauj thiab kev ua haujlwm.
Kev txo qis hauv cov khoom siv hlau siv tau:
Lub xub ntiag ntawm dross txo cov txiaj ntsig ntawm cov hlau siv tau los ntawm kev ua cov khoom siv raw, ua rau muaj kev pov tseg ntau ntxiv thiab kev poob nyiaj txiag.
Oxidative Attack thaum tuav:
Dross, yog tias tsis tshem tawm, tuaj yeem txhawb oxidative nres ntawm cov hlau molten thaum lub sij hawm tuav, cuam tshuam rau cov hlau cov tshuaj stability thiab purity.
Soot Accumulation:
Lub combustion ntawm cov ntaub ntawv organic tam sim no nyob rau hauv dross tuaj yeem ua rau tsub zuj zuj ntawm soot, ntxiv kev nyuaj rau cov txheej txheem metallurgical thiab ua rau muaj kev txhawj xeeb ntawm ib puag ncig.
Kev nyuaj siab hauv kev ua haujlwm hauv qab:
Lub xub ntiag ntawm dross complicates downstream processing cov kauj ruam, xws li casting, dov, los yog extrusion, ua rau nws nyuaj rau ua tau raws li qhov xav tau cov khoom specifications thiab zoo.
Kev mob siab rau kev tshem tawm yog qhov tseem ceeb rau kev tswj hwm purity thiab cov qauv zoo.
► Yuav ua li cas lub dross skim pan leverage natural cais?
Molten hlau muaj qhov ntom ntom ntau dua li cov impurities ua rau dross. Dross pans ua hauj lwm los ntawm skimming nto kom zoo dua ntawm no ntuj sib cais:
Kev sib cais ntuj vim qhov sib txawv ntom ntom:
Cov impurities nyob rau hauv cov hlau molten muaj qhov ntom ntom piv rau cov hlau nws tus kheej. Qhov no natural density sib txawv ua rau impurities,
suav nrog oxides thiab cov khoom tsis yog xim hlau, kom ntab mus rau saum npoo.
Kev Sib cuag nrog Dross:
Tus tsim ntawm lubdross skim panyog xws li tias nws ntab rau saum npoo ntawm cov hlau molten, xaiv los rau hauv kev sib cuag nkaus xwb nrog cov txheej txheem ntab ntab ntawm qhov chaw.
Minimized Hlau Adherence:
Cov duab thiab perforations ntawm lubdross skim panyog engineered los txo cov adherence ntawm cov hlau molten. Qhov kev tsim no tiv thaiv kev sib cuag nrog cov hlau ntau dhau, kom ntseeg tau tias tsuas yog cov txheej sab saum toj ntawm dross adheres rau lub lauj kaub.
Slow Skimming Txheej Txheem:
Skimming yog ua maj mam thiab txhob txwm tshaj tawm kom sib sau ua ke tsuas yog sab sauv txheej ntawm dross. Cov txheej txheem tswj hwm no tiv thaiv qhov tsis tsim nyog poob ntawm cov hlau zoo molten thaum zoo ntes cov impurities.
Kev thauj mus los ntawm Floating Dross:
Raws li covdross skim pantxav mus los ntawm qhov chaw, nws zoo sau cov ntab dross. Lub lauj kaub feem ntau yog nruab nrog cov txheej txheem rau kev thauj cov khoom sib sau ua ke tawm ntawm lub molten da dej, tiv thaiv kev sib kis.
Qhov tsawg kawg nkaus poob ntawm Zoo Molten Hlau:
Lub tswv yim tsim thiab kev ua haujlwm ntawm lubdross skim panxyuas kom meej tias qhov poob zoo molten hlau yog tsawg. Los ntawm tshwj xeeb tsom rau txheej saum toj kawg nkaus ntawm dross, feem ntau ntawm cov hlau molten tseem tsis cuam tshuam thiab tsim nyog rau kev ua haujlwm qis.
Qhov no elegant low-tech tov exploits physics rau tsom dross extraction.
► Yuav ua li cas tom qab tshem tawm los ntawm skimming?
Tom qab skimming, lub dross undergoes ntxiv ua:
- Dross yog emptied los ntawm lub lauj kaub rau hauv receptacles kom txias.
- Dross yuav raug crushed, milled, los yog shredded kom tso hlau.
- Sib nqus sib cais rov qab cov seem hlau nplua nuj.
- Cov ntsiab lus hlau smelted rov qab rau hauv cov dej ntau lawm.
- Cov pov tseg oxide uas tseem tshuav yuav muaj kev siv thib ob.
- Tsawg kawg dross xa mus rau landfilling.
Dross skimming enables high-purity hlau ntau lawm thiab downstream recycling. Xav paub ntau ntxiv txog dross skim lauj kaub, tiv tauj peb ntawmtech@huan-tai.org.
Cov ntaub ntawv:
https://www.thermofisher.com/blog/metals/dross-skimming-enhance-aluminium-recovery/
https://www.tetronics.com/the-dross-dilemma-is-there-a-greener-way-to-treat-this-hazardous-waste/
https://patents.google.com/patent/JPH11236470A/en
https://link.springer.com/chapter/10.1007/978-3-030-05864-7_15
https://www.fst.nl/media/com_form2content/documents/c2/a4246/f2/Dross%20pans%20EN.pdf
https://www.researchgate.net/figure/Typical-dross-compositions-for-various-molten-metals-Redrawn-from-ref-2_fig3_329462851
https://www.thermofisher.com/blog/metals/boosting-productivity-recovering-metal-from-dross
https://www.sciencedirect.com/science/article/pii/S2588863116300105
https://www.asminternational.org/documents/10192/2278238/amp17109p113.pdf
https://www.intechopen.com/chapters/47936
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