Melamine hmoovyog ib tug trimer ntawm cyanamide, thiab nws cov tshuaj zoo li cov hmoov dawb. Raws li cov ntsiab lus, feem ntau siv specifications muab faib ua melamine 99 feem pua thiab 99.8 feem pua. Cov resin ua los ntawm nws yuav tso ib tug loj npaum li cas ntawm nitrogen thaum rhuab thiab decomposed yuav siv tau raws li nplaim hluav taws, dej reducer, formaldehyde cleaner thiab thiaj li nyob. Nws kuj yog ib qho metabolite ntawm cov tshuaj tua kab cyromazine hauv cov tsiaj thiab nroj tsuag.
The primary raw materials for the production of it are dicyandiamide and urea. In 2003, there were about 90 producers globally, with a total capacity of 1 million 334 thousand and 600 tons per year, with the Chinese mainland's annual power reaching 300 thousand tons, accounting for 22 percent of global capacity. Europe is still the leading producer of it globally, accounting for about 34 percent of the total global production capacity; The United States accounts for 12 percent ; Japan accounts for 12 percent ; Other countries account for 20 percent . Changchun enterprise group among Taiwanese manufacturers also produces. Its products manufacture heat hardening resin, moulding materials, cosmetic boards, coatings, adhesives, textiles, paper, etc.
Qhov no yog thawj zaug tsim los ntawm Li Bishi hauv 1834. Nyob rau theem pib, txoj kev dicyandiamide tau siv: calcium cyanamide (CaCN2) tau npaj los ntawm calcium carbide (CaC2), dimerized rau dicyandiamide tom qab hydrolysis ntawm calcium cyanamide, thiab ces rhuab thiab decomposed rau. npaj nws. Vim yog tus nqi siab ntawm calcium carbide, txoj kev dicyandiamide tau raug tshem tawm. Industrial synthesis feem ntau siv urea ua raw khoom. Nyob rau hauv cov xwm txheej ntawm cua sov thiab lub siab siab: uas reacts nrog formaldehyde (HCHO) los ua ke cov resin, uas yuav tshem tawm cov dej. Qhov no Melamine resin yog thermosetting.
Raws li cov xwm txheej sib txawv, cov txheej txheem synthesis tuaj yeem muab faib ua cov txheej txheem siab -siab, qis- txoj kev siab thiab cov txheej txheem atmospheric siab.
1 ib,. Kev tsim cov melamine los ntawm kev siv siab -siab
Pressurize rau 9 8Mpa molten urea yog xa mus rau compression quencher thiab ces nkag mus rau hauv lub synthesis reactor tom qab quench: ntxiv rau, cov kua ammonia yog pressurized rau 9.5Mpa 8Mpa, rhuab mus rau 400C nyob rau hauv lub preheater, gasified thiab xa mus rau lub reactor, uas yog. rhuab nrog molten ntsev. Cov ammonia seem yog txias rau hauv ammonia stripper thiab xa mus rau ammonia stripper los tsim ammonia. Melamine yog sib cais los ntawm slurry nyob rau hauv lub centrifuge, thiab niam cawv yog siv los ua tus nqus ntawm ammonia absorption ntauwd. Tom qab nqus tau, cov ammonia cais nyob rau hauv ammonia distillation ntauwd thiab stripping ntauwd yog rectified thiab xa rov qab nyob rau hauv atmospheric siab raws li kua ammonia rau recycling. Cov melamine sib cais yog qhuav thiab ua hmoov rau hauv lub pulverizer kom tau cov khoom ua kom zoo nkauj melamine.
2. Kev tsim cov melamine los ntawm cov txheej txheem siab -
Tom qab cov chiv qib, ib txoj hlab zis yog yaj hauv lub tank cia. Nws yog txau rau hauv lub reactor nrog ntau lub nozzles. Nrog cov fluidized alumina ua cov catalyst, preheated circulating ammonia yog nkag rau hauv lub reactor kom tswj tau cov kua dej. Cov tshuaj tiv thaiv siab yog atmospheric siab los yog me ntsis siab dua atmospheric siab. Lub reactor yog txawm peem rau nrog ib tug cua sov kauj los tswj cov tshuaj tiv thaiv kub nrog molten ntsev raws li lub cua sov nruab nrab. Cov tshuaj urea evaporates thiab reacts los tsim melamine, carbon dioxide thiab ammonia, nrog rau kev hloov pauv ntawm 95 feem pua. Cov tshuaj tiv thaiv roj tawm los ntawm sab saum toj ntawm lub reactor thiab nkag mus rau hauv lub tshuab cua txias ua ntej. Qhov kub tom qab txias yog siab tshaj qhov dej lwg ntawm melamine. Ntawm qhov kub no, kub kub taw tes los ntawm - cov khoom xws li Miller amine thiab Mibai amine crystallize thiab precipitate, thiab cov hmoov catalyst raug tshem tawm los ntawm lub lim. Cov roj lim tau nkag mus rau hauv sublimator, thiab qhov kub sublimation yog khaws cia ntawm 170C 200 degree C nrog cov roj cua txias. 98 feem pua ntawm melamine yog precipitated los ntawm particle crystallization, thaum lub unconverted urea tseem nyob rau hauv cov roj. Lub melamine siv lead ua thiab cov pa yog sib cais los ntawm cyclone separator, thiab purity ntawm cov khoom yog mus txog 99 9 feem pua, thiab kev sib cais efficiency yog 99 feem pua. Lub circulating gas los ntawm lub cyclone separator nkag mus rau urea scrubber kom txias. Cov khoom tsis zoo thiab cov pa roj melamine thiab cov urea tsis hloov pauv hauv cov roj circulating yog ntxuav thiab zoo zoo hauv cov urea scrubber.
3. Kev tsim cov melamine los ntawm atmospheric siab txoj kev
Cov roj ammonia los ntawm cov khoom siv hluav taws xob ammonia, nrog lub siab ntawm 0.10 0.15Mpa, raug xa ncaj qha mus rau seem melamine. Tom qab preheated rau 350 400 degree los ntawm chav thiab molten ntsev, nws yog siv los ua cov pa roj ammonia ntawm lub txaj fluidized; Cov pa roj los ntawm cov kua urea scrubber muab faib ua ob ntu, ib qho yog xa rov qab mus rau lub crystallizer raws li huab cua txias, thiab lwm yam yog xa ncaj qha mus rau qhov chaw nqus ntawm ammonium bicarbonate / dej qab zib tshauv thiab ammonium chloride los tsim ammonium bicarbonate / soda tshauv thiab ammonium chloride Nws koom ua ke ntawm atmospheric siab ob -qib melamine co- txoj kev tsim khoom thiab ib qho - kauj ruam melamine txoj kev. Yog li ntawd,melamine hmoovr cov khoom lag luam muaj cov khoom zoo, cov khoom siv tsawg tsawg, kev siv zog me me, cov nplai loj thiab kev nqis peev tsawg; Kev nqis peev tau txais kev cawmdim los ntawm 40 feem pua, thiab kev siv hluav taws xob tau txo los ntawm 60 feem pua piv nrog cov txheej txheem siab ib qho - kauj ruam melamine txoj kev; Nws siv cov ammonia ntshiab raws li cov pa roj carbon monoxide, uas tuaj yeem txhim kho kev ua haujlwm ntawm cov khoom siv thiab catalyst los ntawm 30 feem pua; Tsis tas yuav tsim cov cuab yeej siv roj av tshiab, thiab cov roj av tuaj yeem siv tau nyiaj txiag thiab tsim nyog.