Cong Nghe San Xuat AXIT SUNFURIC(1)

8/6/2019 Cong Nghe San Xuat AXIT SUNFURIC(1)

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Trng i hc Bch khoa H NiVin KH CN Mi trng

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Bi tp chuyn mn: Cc qu trnh sn xut c bn

Tn chuyn :

Tm hiu cng ngh sn xut axit sunfuricV Cc dng thi c trng

Nhm thc hin:

- Nguyn Thu Trang- Trn Th Hin- Mai Th Thu- Nguyn Trn Hng

Lp: Cng ngh mi trng - K51

H Ni, 10/2008Mc lc

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Gii thiu 3

A. c im v tnh hnh sn xut axit sunfuric4

B. Vn s dng nguyn nhin vt liu v nng lng10C. Cng ngh sn xut axit sunfuric16

D.1 Vn mi tr ng ca cng ngh sn xut33D.2 Gii php gii quyt nhim41Ti liu thamkho..49

Gii thiu

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Axit sunfuric l mt loi ha cht c bit n t lutrong lch s loi ngi (t th k th 9 bi ngi c coi l pht hin ra cht ny-nh gi kim thut Hi gio IbnZakariya al-Razi (Rhases))Axit sunfuric c s dng rng ri trong cc ngnh khc

nhau ca nn kinh t quc dn. N l sn phm quantrng nht ca ngnh cng nghip ha hc. Cng ngh snxut axit sunfuric, do , l ph bin v rt quan trngtrong nn sn xut.Trong chuyn ny, chng ti xin cp n nhngvn nh sau:

A. c tnh ca axit sunfuric, tnh hnh sn xut trnth gii v ti Vit Nam

{do sinh vin Trn Th Hin trnh by}B. Vn s dng nguyn nhin vt liu v nng lng ca

cng ngh sn xut{do sinh vin Mai Th Thu trnh by}C. Cng ngh sn xut axit sunfuric{do sinh vin Nguyn Trn Hng trnh by}D. Vn mi tr ng ca cng ngh sn xut axit

sunfuric v mt s gii php gii quyt nhim{do sinh vin Nguyn Thu Trang trnh by}

Sau y l ni dung chi tit.

A.C IM V VAI TR CA AXIT SUNFURIC

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c im:

H2SO4 l axit hot tnh mnhCht lng, khng mu

Kt tinh nhit 10,450C, si nhit 296,20C

H2SO4 ha tan SO3 gi l oleum (20, 25, 30,35 65% SO3).Thc t hay sn xut oleum v c th to axit vi nng

khc nhau

Vai tr :

Hu nh mi ngnh sn xut ha hc trn th gii u

trc tip hoc gin tip s dng axit sunfuric. Chng ta c

th bt gp axit ny trong cc ngnh sn xut phn

bn(Supephotphat,amoniphotphat),thuc tr su,cht

git ra tng hp,t si ho hc,cht do,sn mu,phm

nhuc,dc phm,ch bin du m,v,v..C th ni axit

sunfuric ca mt quc gia l mt ch s tt v sc mnh

cng nghip ca quc gia . Vai tr quan trng c

th hin rt c th thng qua tnh hnh sn xut axit

sunfuric trn th gii v trong nc.

Tnh hnh sn xut axit Sunfuric trn th gii:

Bi nhng c

tnh quan trng caaxit sunfuric v nhu

cu ln ca nn sn

xut cng nghip

ha hc m sn lng

4

Sn lng axit sunfuric

4.218.8

47

100

165

0

50

100

150

200

1900 1937 1960 1986 2001 Nm


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axit ny trn th gii ngy cng tng. Di y l biu

th hin s gia tng :

Trong M c coi l mt trong nhng nc sn xut

axit sunfuric ln nht trn th gii. y l th v sn l-

ng axit sunfuric m M sn xut nhng thp nin tr-

c:

Theo Vn Express, hin nay Trung Quc cng c coi l

nc sn xut H2SO4 ln trn th gii. nc ny phng php

sn xut i t qung pyrit l ch yu. Theo Hip hi axit

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Tnh hnh sn xut axit sunfuric trong nc:

Vit Nam axit sunfuric cng c sn xut rt rng ri phc v cho nn cng ngip ha hc nc nh. C th k

n 3 cng ty sn xut axit sunfuric ln trong nc (s liu

ly t trang web ca S khoa hc cng ngh Bn Tre),

l:

Nh my Supephotphat Lm Thao Ph Th: sn xut

H2SO4 i t qung pyrit phi trn vi lu hunh ha lng

nhp khu. Ch bng vic thay i t l phi trnnguyn liu kt hp ci tin cng ngh t l, nh my

bin cng ngh c ca Lin X thnh dy chuyn sn xut

H2SO4 cha tng c, tn dng ngun nguyn liu pyrit trong

nc v gim trit cht thi gy nhim. Nh t

nm 1995 tr li y sn lng axit sunfuric lun t 360

tn /ngy, bi x bay ra gim xung ti mc tiu chun v

x thi gim t 280 tn xung 80 tn /ngy, thu hi cton b lng axit phi thi b trc y. Ti y H2SO4 c

sn xut theo phng php tip xc, cht xc tc oxi

ha SO2 thnh SO3 l vanai oxit.

Nh my Supe ln Long Thnh Bn Tre hng nm sn

lng H2SO4 t khong 80.000 tn /nm vi nguyn liu l

qung sulfua st, sn xut theo phng php tip xc

(cht xc tc l V2O5). Theo bo co ca cng ty Phn bnmin Nam, mc d gi lu hunh nguyn liu tng mnh nh-

ng p ng nhu cu tng t bin, Nh my

Supephotphat Long Thnh thuc Cng ty vn y mnh

sn xut axit sunfuric ngay t nhng ngy u nm. Tnh

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n 25/1/2008 nh my sn xut gn 7000 tn axit

sunfuric, t trn 10% k hoch c nm v tng gp trn 3

ln so vi cng k nm 2007.

Nh my ha cht Tn Bnh sn xut H2SO4 k thut it nguyn liu lu hunh theo phng php tip xc. H2SO4tinh khit c sn xut bng cch chng ct H2SO4 k thut

.Ngy 12/6/2008 trang www.vinachem.com.vn vit:

Theo bo co ca Ban K hoch - Kinh doanh Tng Cng ty

Ho cht Vit Nam (TCT HCVN), p ng axit cho

sn xut phn ln v nhu cu th trng, t u nm n

nay cc n v sn xut vn m bo tt tin sn xutaxit sunfuric trn c s vn hnh thit b cao ti, chun

b nguyn liu (lu hunh) cho sn xut.

Trong thi gian qua gi lu hunh tng cao t bin, ln

mc 700-800 USD/tn trc tip tc ng mnh n gi

thnh sn phm axit, iu ny lm cc nh sn xut gp

rt nhiu kh khn v vn, v hch ton sn xut, nht l

khi axit c s dng trong sn xut phn ln, s lm igi sn phm phn ln trong bi cnh phn bn phi thc

hin bnh n gi theo ch o chung. Ngoi ra, gi thnh

axit cao cng s nh hng n cc ngnh khc nh sn xut

cquy ch, sn xut phn nhm v nhiu sn phm khc.

Tnh n 5/6/2008, ba n v sn xut axit sunfuric ca

TCT thc hin c sn lng axit tng ng 47% k

hoch c nm, tng 20,5% so vi cng k nm 2007. Trong trn 80% c s dng trong sn xut phn bn. Lng

axit thng phm cng t trn 47% k hoch c nm, tng

gn 8% so vi cng k nm 2007.

8
http://www.vinachem.com.vn/http://www.vinachem.com.vn/


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S LC V CC CNG NGH SN XUT AXIT SUNFURIC:

C 2 phng php:

Phng php tip xc: dng V2O5 hoc K2O lmxc tc

Phng php thp: dng NO lm xc tc, xy ra

trong thp m

-Phng php tip xc cho nng axit cao (98 99%), tuy

nhin chi ph cao. Trong phng php tip xc bao gm:

phng php tip xc n v tip xc kp. Ngy nay trn

th gii v trong nc s dng ch yu phng php tip xckp vi xc tc l V2O5

-Phng php thp: chi ph u t n gin nhng nng

axit ch t 70 75%. Phng php ny ch c dng trong

trng hp sn xut hn hp axit sunfuric v nitric.

D i t ngun nguyn liu no th qu trnh sn xut

H2SO4 cng tin hnh theo 4 giai on chnh:

-To SO2 bng cch t nhin liu cha S

-Tinh ch kh (lm sch tp cht c trong kh)

-Chuyn ha SO2 thnh SO3

-Hp th SO3 bng H2O to H2SO4

B.c im s dng nguyn nhin vt liu v nnglng trong cng ngh sn xut axit sunfuric.

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1. Nguyn liu:+) Nguyn liu sn xut axit sunfuric rt phong ph

bao gm lu hunh v cc hp cht ca n. Theo thng k,sn lng axit sunfuric trn th gii c sn xut t cc

ngun nguyn liu nh sau:-Lu hunh nguyn cht-Qung pirit FeS2, cha 30-50% S, ln nhiu tp cht

v thnh phn khc.-Cc ngun cht thi cha S ( cc ngun kh thi nh

H2S, SO2, axit sunfuric thi.)-Thch cao.

a) Lu hunh nguyn cht:- S l mt trong nhng nguyn t c nhiu trong t

nhin. S chim 0,1% khi lng v tri t. S c nh gi lmt trong nhng nguyn t quan trng nht v c nhiung dng trong cng nghip. S c s dng ch yu trongcc ngnh cng nghip sn xut axit sunfuric (chimkhong 50% tng lng S sn xut ra), trong nng nghipchim khong 10-15% tng lng S sn xut ra).

- Trong t nhin lu hunh dng n cht c th tm

thy gn cc sui nc nng v cc khu vc ni la tinhiu ni trn th gii, c bit l dc theo vnh ai laThi Bnh Dng. Cc ngun ph bin ny l c s cho tngi truyn thng brimstore do lu hunh c th tm thy gn cc ming ni la. Cc trm tch ni la hin ckhai thc ti Idonesia, Chile v Nht Bn.

- Cc m ng k ca lu hunh cng tn ti trong cc mmui dc theo b bin thuc vnh Mxic v trong ccevaporit ng u v Ty . Lu hunh trong cc m ny -

c cho l c c nh hot ng ca cc vi khun k i vicc khong cht sunfat c bit l thch cao. Cc m nyl nn tng ca sn xut lu hunh cng nghip ti Hoa K,Ba Lan, Nga, Turkmenistan. Lu hunh thu c t du m,kh t v ct du Athabasca tr thnh ngun cungcp ln trn th trng vi cc kho d tr ln dc theoAlberta.

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- Vit Nam, iu ch lu hunh, ngi ta i tqung S thin nhin cha khong 15-20% S hoc tch cchp cht t kh thi ca cc ngnh cng nghip luyn kimmu, gia cng du m, kh thin nhin, kh du m.

b) Qung pirit:C 3 loi qung pirit thng dng sn xut axit

sunfuric l:+ Pirit tuyn ni: Trong qu trnh em luyn ng th-

ng dng phng php tuyn ni lm giu ng caqung ln khong 15-20% ng ca qung (gi l tinhqung ng). Phn b thi ra ca qu trnh tuyn nicha khong 32-40% S gi l qung pirit tuyn ni.

+ Pirit ln than: Than 1 s m c ln c qungpirit, c loi cha ti 3-5% S lm gim cht lng ca than.V vy, phi loi b cc than c ln pirit. Phn than cc loib ny cha ti 33-42% S v 12-18% C gi l pirit ln than. min bc nc ta, m than Na Dng (Lng Sn) than chanhiu S (c mu ti 6-8% S). Vic nghin cu tch c Skhi than c ngha kinh t k thut rt ln v tng ccht lng than, m bo an ton, ng thi tn dng cS.

+ Pirit thng: thnh phn ch yu l FeS2 cha khong53,44% S v 46,56% Fe. Trong qung c ln nhiu tpcht ca cc hp cht ca ng, ch, km, niken, bc, vng,coban, selen, telu, silic, cc mui cacbonat, sanfat canxi,magie. V vy hm lng thc t ca S dao ng trongkhong t 30-52%. min bc nc ta mi ch pht hinmt s m pirit nhng ni chung hm lng S thp (khong20-30% S), tr lng nh.

-M st N Lng thuc a phn x Duyt Trung, th

x Cao Bng tr lng khong sn hin ti cn hn 8 triutn vi hm lng gn 60% Fe, khong 30% S.-M ng Sin Quyn thuc x Bn Vc v Cc M, huyn

Bt Xt, tnh Lo Cai. Theo thit k, m c cng sut khaithc 1,1-1,2 triu tn qung nguyn khai/ nm. Cng sutthit k nh my luyn ng (cng ty ng Lo Cai)41.738 tn tinh qung, hm lng 25% Cu/nm sn xut

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1000tn Cu hm lng 99,95% cng cc sn phm khc nhvng, bc, tinh qung st, tinh qung pirit.

- M km ch ch in: thuc cc x Bn Thi, Qung Bchv ng Lc, huyn Ch n, tnh Bc Cn. Sn lng khai

thc hng nm khong 50000 tn qung xit v 40000 tnqung pirit. Tr lng cn li n u nm 2004: qungxit 0,88 triu tn, qung pirit 0,513 triu tn

- M km ch Lang Hich: thuc x Tn Long, huyn ngH, tnh Th i Nguyn, sn lng khai thc t trung bnh15000 tn qung/ nm. Tr lng cn li n u nm2004: qung xit 227.267 tn, qung pirit 37.600 tn.

- M pirit huyn Ba V, tnh H Ty (nay thuc aphn H Ni). Cc thn qung pirit nm trong tp vn

ni la ca h tng tui pecmi- Triat. Qung c ngungc nhit dch, lien quan mt thit n cc hot ngphun tro trung tnh v axit. Cc than qung c cu tort phc tp, cht lng v b dy bin i theo ng ph-ng v hng dc. Qung c hm lng S t 4-20%, tr lngtheo nh gi tm kim khong chc triu tn

c) Cc ngun cht thi cha S:- Kh l luyn kim mu: Kh l trong qu trnh t cc

kim loi mu nh qung ng, ch, thic, km c chanhiu SO2. y l mt nguyn liu r tin sn xut axitsunfuric v c sn xut 1 tn ng c th thu c 7,3 tnS02 m khng cn l t.

- Kh hydrosunfua(H2S): Trong qu trnh cc ho thankhong 50% tng lng S c trong kh than s i theo khcc, ch yu dng H2S (chim khong 95%). Lng H2Strong kh cc hng nm trn th gii c th ln ti hangtriu tn. Vic thu hi lng H2S ny khng nhng c

ngha v kinh t m cn c ngha v mt v sinh mitrng.- Khi l: Hng nm trn th gii t hng t tn than,

trong khi l thi vo kh quyn hng chc triutn S. y cng l ngun nguyn liu ng k snxut axit sunfuric.

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- Axit sunfuric thi: Sau khi dng axit sunfuric lm tcnhn ht nc,tinh ch du m, sunfua ho cc hp cht huc s thu c cht thi cha nhiu H2SO4 ( 20 50%). Victhu hi axit sunfuric ny cng c ngha rt ln v mtkinh t v bo v mi trng.

d) Thch cao:y l mt ngun nguyn liu phong ph sn xut

axit sunfuric v nhiu nc trn th gii c m thch cao( CaSO4.2H2O hoc CaSO4). Ngoi ra qu trnh sn xutaxit photphic, supe phophat kep cng thi ra mt lng lnCaSO4. Thng thng t t thch cao ngi ta sn xut lienhp c axit sunfuric v xi mng.

e) Cht xc tc:Trong cng ngh sn xut axit sunfuric cht xc tc

ng vai tr rt quan trng trong giai on chuyn hoSO2 thnh SO3. cc cht xc tc trong qu trnh xi hoSO2 c th chia lm hai nhm.

- Nhm I l cc xc tc cha platin gm platin l cu thot tnh c mang trn cc cht mang nh aming,silicagen v mt s cht khc.

- Nhm th II bao gm cc xt kim loiTrong lch s ca cng ngh sn xut axit sunfuric,

u tin ph bin l dng xc tc cha platin, sau dngxc tc sat xit. Trong my chc nm gn y, trn thgii cng nh nc ta xc tc c dng ph bin nht lvana ixit ( V2O5 ) cng vi mt s ph gia khc nh Al2O3,SiO2, K2O, CaO Cc cht ph gia c tc dng lm tng bn c hc, nng cao hot tnh ca cht xc tc, t bng c bi cc tp cht. Xc tc platin co hot caonht, trn xc tc ny xy ra phn ng xi ho SO2 dinran gay nhit 400 C. Xc tc cha vana ixitchim v tr th hai, cn trn xc tc Fe2O3 phn ng nych din ra nhit 600 C. Mc d b ng cbi asen xit As2O3 cng theo trt t nh trn.

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2.c im s dng nguyn liu:Mc d i t nhiu loi nguyn liu khc nhau d sn

xut axit sunfuric nhng chng u c im chung l tnguyn liu to ra SO2. Trc khi t phi tri qua giai

on gia cng c, nhit tu theo dng nguyn liu.-S trc khi ua vo l t phi p nh, nu chy, lc

loi b tp cht. S dng lng c khng kh nn uavo l t s ho hi v chy y thu c SO2 t ti16%.

- Qung pirit thng thng c kch thc 50 200 mm vvy phi tri qua cc cng on p, nghin, sng ckch thc nht nh ( tu thuc vo loi l ). V d trongl t tng si ngi ta cn loi b cc ht qung c kch

thc ln hn 3mm, hn ch cc ht qung c kch thc nhhn 44x1O-3 mm. Bi v nhng ht qu to hay qu nhu nh hng n bi x pirit cun theo kh l trong qutrnh t nguyn liu do tt c cc ht rn c tc tihn nh hn hoc bng tc lm vic ca kh u bcun theo kh l vo h thng sn xut pha sau khinchng ta phi x l kh SO2 thu c. Mt khc, qung ckch thc qu nh qu d b kt khi nhit cao.

Qung tuyn ni phi sy s b gim hm kng

m.- Thch cao cng p nghin, sng c kch thc

nht nh.

3. Nhin liu v nng lng:a) Than.

- Trn lnh th Vit Nam than c phn b theo khuvc:

+B than atraxit Qung Ninh nm v pha ng BcVit Nam, ko di t Ph Li qua ng Triu n Hn Gai-Cm Ph - Mng Dng- Ci Bu- Vn Hoa di khong 130Km, rng t 10 n 30 Km, c tng tr lng khong 10,5t tn, trong : tnh n mc cao -300m l 3,5 t tn c tm kim thm d tng i chi tit, l i tng chothit k v khai thc hin nay, tnh n mc cao -1000m

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c tr lng d bo khong 7 t tn ang c u t tmkim thm d. Than Antraxit Qung Ninh c cht lng tt,phn b gn cc cng bin, u mi giao thng... rtthun li cho khai thc v tiu th sn phm.

+B than ng bng sng Hng : nm trn trong vngng bng chu th sng Hng, c nh l Vit Tr vcnh y l ng b bin ko di t Ninh Bnh n HiPhng, thuc cc tnh thnh ph: Tha Bnh, Hi Dng,Hng Yn, Hi Phng, Bc Ninh, Bc Giang, H Ni, SnTy, H Nam, Ph L, Phc Yn, Vnh Yn v d kin cnko di ra vng thm lc a ca bin ng Vit Nam...Vi din tch khong 3500 Km2, vi tng tr lng d bokhong 210 t tn. Khu vc Khoi Chu vi din tch80Km2 c tm kim thm d vi tr lng khong 1,5 ttn, trong khu vc Binh Minh, vi din tch 25Km2 c thm d s b vi tr lng 500 triu tn hin ang ctp trung nghin cu cng ngh khai thc m m utin. Cc va than thng c phn b su -100

+ Cc m than vng ni a: C tr lng khong 400triu tn, phn b nhiu tnh, gm nhiu chng loithan: Than nu-la di (m than Na Dng, m than ngGiao); than bn Antraxit ( m than Ni Hng, m thanKhnh Ho, m than Nng Sn); than m ( m than Lng

Cm, m than Phn M, m than Khe B)..., c nhiu mthan hin ang c khai thc.

+ Cc m than bn: Phn b hu khp 3 min: Bc,Trung, Nam ca Vit Nam, nhng ch yu tp trung minNam Vit Nam, y l loi than c tr cao, nhit lngthp, mt s khu vc c th khai thc lm nhin liu, cnli ch yu s c s dng lm phn bn phc v nngnghip. Tng tr lng than bn trong c nc d kin c

khong 7 t mt khi.

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CC S LIU NI BT (Tr.tn)

NmTHANNGUYN

KHAI

THAN TIUTH

THAN XUTKHU

2001 14.6 13.0 4.2

2002 17.1 14.8 5.52

2003 20.0 18.8 6.5

2004 27.3 24.7 10.5

2005 34.9 30.2 14.7

2006DK 40.1 36.9 21.3

- Than l ngun nhin liu chnh cung cp nhit trongsut qu trnh sn xut axit sunfuric nht l trong l tnguyn liu v c tr lng ln, nhit tr cao, gi thnh r sovi cc cht t khc. Nhit c nh hng rt ln trong qutrnh t qung pirit. Nhit cng cao qu trnh chyxy ra cng nhanh nhng khng th tng nhit mt cchtu nh vy s gy nn hin tng kt khi ca nguyn liulm gim r rt tc ca qu trnh v dn n tc lngng sn xut. Mt khc nhit tng cao s lm gim bn ca l. Do vy ngi ta thng duy tr nhit caqu trnh t pirit t 600 800 C.Vt qu gii hn nyu khng c li.

b) Lng xy thi vo l:xy thi vo l cng nhiu tc qu trnh chy ca

qung pirit cng nhanh, nhit ca qu trnh to ra cngln dn n nhit ca l t tng cao vt qu nhit

thch hp. Mt khc xy qu d tha s lm gim nhit l do tiu tn nhit cho qu trnh t nng khng kh ( O2v N2) v s pha long hm lng SO2 di 7%. iu ny khngc li cho qu trnh xi ho SO2 thnh SO3.

Trong thc t, ngi ta cng phi khng ch xy vo lsau qu trnh chy cn d li khong 11% trong hn hp kh

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ra khi l t xy dng xy ho SO2 thnh SO3 giai on tip theo

Ngy nay ngi ta bt u s dng khng kh giu xy y chy qung pirit. Lm nh vy hn hp kh thu c

c hm lng SO2 cao v cha t nit.

c) in:Trong qu trnh sn xut axit sunfuric in c dng

vn hnh my mc, thit b hot ng.

d) Nc:Nc c s dng trong qu trnh hp th SO3, lm lnh

dung dch ti tun hon trong thp hp th

C.Cng ngh sn xut axit sunfuric

tm hiu c cng ngh sn xut axit sunfuaric,

trc ht chng ta cp ti mt s tnh cht ho hc c

bn nht ca axit sunfuric vi mc ch chn c vt liu

thch hp ch to thit b sn xut, bo qun v vn

chuyn n:

- Axit sunfuric khan l cht lng khng mu, snh

( khi lng ring 200C l 1,8305 gam/cm3), kt tinh 10,37 0C. p sut thng n si 296,2 0C.

- Trong ho hc axit sunfuric c xem l hp cht ca

anhydrit sunfuric vi nc. Cng thc ho hc: SO3H2O.

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- Trong k thut: hn hp theo t l bt k ca SO3 vi

H2O u gi l axit sunfuric.

+ Nu t l SO3/H2O < 1 ngi ta gi l dung dch axit

sunfuric. T l SO3/H2O > 1 gi l dung dch ca SO3 trongaxit sunfuric hay oleum hoc axit sunfuric bc khi .

- Mc d c cc phng php khc nhau sn xut

axit sunfuric tuy nhin chng c im chung l u c

5giai on chnh:

+ t nguyn liu sn xut SO2.+ Tinh ch kh SO2.

+ O xy ho SO2 thnh SO3.

+ Hp th SO3 to thnh H2SO4 .

Bi vy cng ngh m chng ti trnh by y

cng c chia thnh 4 giai on chnh nh trn.Chng ta

c th tham kho s cng ngh ca phn xng sn

xut H2SO4 ca nh my supe photphat LONG THNH

I.Chun b nguyn,nhin vt liu:

Chun b

nguynliu

Sn xutkh SO

2

Tinh chkh SO

2

Oxy haSO

2

SO3

Hp thkh SO

3

BiQung X qung Bi,

nc thi

Kh thiSO

2, SO

3

Honthnhsn

phm

Bi

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_Nguyn liu sn xut axit sunfuric c trnh by

trn,phn nguyn nhin vt liu sn xut axit. y chng

ti s cp chi tit hn v cng vic chun b nguyn,nhin

vt liu.

1.Nguyn liu:

_Nguyn liu c nghin nh c kch thc nht

nh,sng lc, a qua cc l t.

_ qu trnh t nguyn liu tn nhit,ta cn lc bi

ngay t giai on ny,d sau giai on ny vn cn phi lc

bi thm na.

_Qung phi c sy kh gim hm lng m, trnh tn tht nhit trong qu trnh t ngyn liu.

2.Nhin liu:

_V qu trnh sn xut axit sunfuric cn tiu tn mt

lng nhit kh ln nn cn cung cp nhit trong hu ht cc

giai on ca qu trnh sn xut,do cn c ngun cung

cp nhit,m y ch yu sdng than t.

_Cc ngun nhin liu cha O2 l rt cn thit,bi trong

giai on t nguyn liu cn nhiu O2.

II. t nguyn liu sn xut SO2:

_i vi cc ngun nguyn liu c sn SO2 th ta chuyn

ngay qua giai on tinh ch kh SO2(S c ni phn

sau).

_i vi cc ngun nguyn liu th s,l hp cht caSO2 th cn qua giai on t to ra SO2.

_Cc ngun nguyn liu cha S,qung pirit,.l nhng

ngun nguyn liu c s dng ch yu trong qa tinh

sn xut axit sunfuric;ngoi ra cng c rt nhiu ngun

19


20/57

koasc,trong phi k n axit sunfuric d tha trong cc

qu trnh trc.

3.1- Cc phn ng ho hc trong qu trnh t nguyn

liu:- i vi qung py rit:

4 FeS2 + 11 02 --------> Fe2O3 + 8 SO2 + Q

2 FeS2 --------> 2 FeS + S2.(nhit vo khong

5000C).

S2+ 2 O2-----> 2 SO2

4 FeS + 7 O2 --------> 2 Fe2O3 + 4 SO2

Hoc 3 FeS +5 O2 ----------> Fe3O4 + 3 SO2

- Qa trnh chy ca qung khng nhng ch xy ra

gia pyrit v Oxy m cn xy ra gia cc pha rn:

FeS2 + 16 Fe2O3 = 11 Fe3O4 + 2 SO2

FeS + 10 Fe2O3 = 7 Fe3O4 + SO2

FeS2 + 5 Fe3O4 = 16 FeO + 2 SO2

FeS + 3 Fe3O4 = 10 FeO + SO2

- i vi Pyrit ln than c thm phn ng :

C + O2 = CO2

Phn ng trn s cung cp thm mt phn nhit lng

cn thit cho qu trnh t nguyn liu.

- i vi thch cao :

CaSO4 = CaO + SO2 (Phn ng din ra 1400 1500 0C).

Khi c C, SiO2, Al2O3, Fe2O3 nhit ca phn ng

trn gim xung

2 CaSO4 + C = 2 CaO + 2 SO2 + CO2

20


21/57

- i vi kh thi

S + O2 = SO2

2 H2S + 3 O2 = 2 SO2 + 2H2O

Thng thng thnh phn ca kh l bao gm SO2, O2,N2,, hi nc v mt s tp cht khc nh: bi, SO3, AS2O3,

SeO2; HF; S F4

3.2- Cc loi l t thng dng:

Ngy nay cng ngh sn xut axit sunfuric c nhiu

loi l dng t nguyn liu nh: l nhiu tng, l t

qung bt, l lp si, l xyclon; l dt lu hunh (loi nmngang, loi ng), l t hyrosunfua H2S

Do gii hn bi vit chng ti trnh by loi l lp si

t nguyn liu. Bi v thit b lp si c nhiu u

im ni bt v ngy cng c s dng rng ri khng

ch trong cng ngh sn xut axit sunfuric m cn trong

cc ngnh khc nh: luyn kim, gia cng du m, thc

phm, y hc, nng lng ht nhn

+ Theo bo co ti nghin cu khoa hc cng ngh

cp nh nc KC- 06-06 chng ta c bng cn bng vt liu

cho 1 tn qung py rit hm lng 33% lu hunh i vi l

lp si (da trn tnh ton l thuyt) nh sau:

Bng 1

Lng vo Lng raThng s Trng

l-

Th

tch

Thng

s

Trng l-

ng(kg)

Th tch

m3/ tn

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ng(kg) m3/tnQung 1000 X 750,8Qung

kh

940 kh l 2821,35 1999

Qung m 60 Kh

SO2

638,4 223,4

khng kh 2571,5 2010,2

7

Kh

SO3

6,8 1,9

Khng kh

kh

2526 1953,6

7

O2 141,4 99

Hi nc 45,5 56,6 N2 1929,25 1543,4

Hi n-c

105,5 131,3

Tng 3571,5 3572,15Nhit l ng cn thit cho qu trnh

t

Bng 2

Lu hunh

33%

Luhunh

35%Nhit vt l ca qung

(kcal /h )

12729,2 12729,2

Nhit ca m trong qung

(kcal /h )

6250 6250

Nhit ca khng kh kh(kcal /h )

6285,4 66887

Nhit ca m trong khng

kh (kcal /h )

2114,2 2249,7

Nhit to ra kh t (kcal 4266670 4533337

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/h )Tng lng nhit cn cung cp

(kcal /h )

4350620,8 4621453

Cu to l lp si (hnh 2) gm 1 hnh tr bng thp,

bn trong lt vt liu chu la. phn di ca l t 1

bng phn phi khng kh u trn ton tit din

ca n. Qung c a vo bung np. Khng kh qua cc

l ghi ng thi qung vo l. Khng kh chnh qua cc

m gi trn bng phn phi kh gi cho lp qung trng

thi si. qung chy trit , ngi ta b xung khng

kh vo trn lp si (khong 20% tng lng khng kh).

ng tho s t ngang mc lp si. Tc khng kh

qua l m gi khong 8- 10 m/s. Tng din tch l ca tt

c cc mi gi ch chim chng 2% din tch bng phn

phi kh. Khi t qung tuyn ni, tc kh trong l

1-1,1 m/s, cng l 8-10 tn qung 45% lu hunh/m2/

ngy. Nu t qung pyrit th tc kh ln hn (1,9-2

m/s) v do cng l cng cao hn (16- 20 tnqung/m2/ngy).

L lp si c u im :

+ t c cc qung ngho lu hunh nhng hiu sut

to ra SO2 vn cao .

+ Cu to thit b tng i n gin d c kh ho

v t ng ho .

+ H s truyn nhit, dn nhit t lp si n b

mt trao nhit rt ln.

+ Tr lc ca lp si khng ln lm v trong gii hn

tn ti lp si th khng ph thuc vo tc kh.

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24/57

Tuy nhin n c mt s nhc im:

+ Hm lng bi trong kh ra rt ln cho nn phi c

thit b x l bi trong SO2 to ra.

Di y l bng lng bi cun theo kh l i vi luhunh 33%

Bng 3

Uop(m

/s)

0,85 0,9 1,02 1,08 1,14

Rt(kg/s)

0,2124 0,26 0,392 0,434 0,506

Cp(%) 18,5 22,4 33,82 37,41 43,6

Trong :

Lng qung vo l : FO =1,16kg/s.

Kch thc trung bnh ca ht: Dp = 84x 10-3 mm

Uop: tc lm vic ca kh

Rt: khi lng bi .

Cp: phn trm bi cun theo kh l

+ Thnh l vng lp si b bo mn rt mnh cho nn

phi thng xuyn kim tra v bo dng.

Do c nhiu u im ni bt nn l lp si ang dn

thay th loi c kh v tip tc c nghin cu c nngsut cao hn v nhiu tnh u vit hn. Di y l ch

tiu lm vic ca mt l lp si i vi cc ht c kch thc

khc nhau (c tnh ton da trn l thuyt).

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Bng 4

Dp (10-6

m

)

69 84 155 274 382 474-

500Umf

(m/s)

0,00

2

0,004

4

0,015 0,047 0,08 0,143

Ut (m/s) 0,84 1,02 1,91 4,14 4,65 6,09Uop

(m/s)

0,9 0,9 0,9 0,95 1,14 1,3

d T( m )

0,1 0,1 0,1 0,1 0,11 0,13

Ub

(m/s)

1,6 1,6 1,6 1,5 1,8 1,96

H ( m ) 1,14 1,14 1,13 1,14 1,24 1,22

Trong :

Dp: kch thc trung bnh ca tp hp ht.

Umf: tc si ti thiu .Ut: tc ti hn ca ht rn.

Uop: tc lm vic ca kh.

dT : ng knh trung bnh cua bt kh trong lp

si.

Ub: tc nng ca bt kh .

H: chiu cao lp si cho cc mu nguyn liu

S dng x v nhit:

- Khi t qung pi rit thi ra mt lng x kh ln

(khong 70% lng qung kh) vi thnh phn ch yu l

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26/57

st oxit, ngoi ra cn c mt s kim loi mu v qu nh:

Cu, Co , Zn , Au , Ag , Ta .y l ngun nguyn liu qu

cho ngnh cng nghip luyn kim .

- Nu s dng tng hp c x th c 1000 tn x cth thu c 800 tn tinh qung st (vi hm lng 55- 63 %

Fe); 3,3 4 tn ng; 3,3 4,3 tn km; 0,8-1 kg vng; 10

kg bc; 80 kg coban; 70 tn natri sunfat

- Lng nhit to ra khi t nguyn liu chim t 52

65 % tng lng nhit. Chng ta c th tn dng lng ny

sn xut in t cung cp cho nh my (tnh n

hiu sut nhit ca nh my in) hoc nh my snxut c th tr thnh ni cung cp nng lng.

III. Tinh ch kh SO2

1. S lc v qu trnh tinh ch kh:

- i vi s c in ca qu trnh sn xut axit

sunfuric theo phng php tip xc:

+ Kh l t l t qung c lm ngui trong ni hi,tch bi trong xyclon, lc in kh c nhit 300-400o C

i vo cng on lm sch kh tch cc tp cht c hi

i vi xc tc. Kh SO2 thu c sau khi t nguyn liu

cha nhiu tp cht c hi nh :

- Bi: lm tng tr lc ca thit b v ng ng, lm

gim h s truyn nhit, chuyn cht

- AS2O3: lm xc tc b ng c vnh vin, lm gim

hiu sut chuyn ho SO2.

- SeO2, TeO2 , Re2O7 ho tan vo cc axit ti lm bn

sn phm. Mt khc chng cn l ngun nguyn liu qu

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cho cc ngnh cng nghip bn dn, thu tinh muBi

vy phi tm cch thu hi chng .

- FLo( dng HF v SiF4) : n mn cc vt liu c cha

Silic trong iu kin thun li c th gim hot tnh cacht xc tc.

+ lm sch hn hp kh,ngi ta cho kh i qua

hng lot cc thp ra, lc in, sy Tuy nhin s lm

vic ca chng kh phc tp, v c mt nhc im l cc

tp cht ch yu trong kh l chuyn thnh dng m axit

sau li phi tch chng trong cc lc in t. Hin nay

c 2 hng gii quyt n gin hn nh sau:- Phng php hp th: Lm ngui kh bng dung dch

axit sunfuric c nng v nhit sao cho cc tp cht

trong kh b hp th trn b mt axit ti m khng to m.

Nu trong kh l, ngoi hi H2SO4 cn c c hi SeO2 v

As2O3 th tng nhit axit ti, hiu sut tch 2 cht trn

khi kh l cng tng. S d nh vy v chng ho tan

trong c axit ti v m axit. Khi tng nhit lng m s

gim, do lng SeO2 v As2O3 trong m theo kh cng

gim.

- Phng php hp ph: dng cht rn hp ph tp cht

nhit cao m khng cn phi lm ngui v ra hn

hp kh. Cht hp ph As2O3 tng i tt l silicagel. Thc

t n c th hp ph hon ton As2O3 khi kh l. Cht

hp ph c kh nng hp ph cao hn v r hn l zeolit

nhn to (thnh phn gn ng 10SiO2..O,5AL2O3). N c

th hp ph c lng As2O3 bng 5-7% khi lng ca n.

_ Trong giai on tinh ch kh SO2,thit b trong

cc qu trnh tinh ch lun phi tip xc nhit nn

trnh cho thit b qu nng,gim thI lng nhit cp ra mI

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trng,ta cn lm ngui thit b bng cch cho i qua cc

thp lm lnh.

2- Thit b lm sch kh gm:

+ Thp ra I: c nhim v lm ngui hn hp kh t350-400o C xung 80-90oC. Tch hu ht lng bi cn li

trong kh sau lc in kh. Tch mt phn SeO2 v As2O3v cc tp cht khc. Hp th mt phn m a xit to thnh

trong thp.

+ Thp ra II: c nhim v lm ngui hn hp kh t

80-90oC xung 30-40oC. Hp th mt phn m a xit trong

kh sau thp ra I. Tch mt phn cc tp cht ( Asen,telu) khi hn hp kh.

+ Thp tng m: c nhim v tng hm m ca hn hp

kh tng kch thc ht m a xit. Tip tc lm ngui

hn hp kh xung vi na (3-5oC). Nu trong hn hp

kh c Flo th thp tng m ngi ta cn cho thm Na2SO4vo a xit ti tch chng theo phn ng:

3 SiF 4 + 2 Na2SO4 + 2 H2O = 2 Na2SiF6 + 2 H2 SO4 +SiO2

+ Lc in t: lc m axit ngi ta thng dng loi

lc c kh: lc si . Nguyn tc lm vic ca loi ny l cho

hn hp kh c m axit i qua lp si mnh chu axit, khi va

chm vi cc si, do lc cc ht m axit s b gi li trn .

ng knh ht m cng ln, tc dng kh cng cao th

hiu sut tch m cng ln.+ Thp sy: Nhim v tch hon ton lng hi nc

trong hn hp kh thng thng bao gm 2 thp vi mc

ch phng 1 trong 2 thp c h hng v tng lng

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29/57

Oleum sn xut c v nht l gim lng m a xit khi

sy.

Cng on lm sch kh phi m bo mt s ch tiu

sau:Hm lng bi trong kh sau lc in kh,g/m3

8,5

Nng a xit ti ,% H2SO4

Thp ra I 55-70

Thp sy 93-95

Hm lng tp cht trong kh vo thp tip xc,mg/m3

Asen O

Flo


30/57

tip SO3 hay H2SO4 m sn phm trung gian l

nitrozonihidrosunfat.Ta c phn ng sau:

2SO2 + O2 +NO + NO2 + H2O = 2 NOHSO4

Dng nc ho tan sn phm ny trong bung lmbng ch s thu c axit sunfuaric v hn hp cc kh NO

v NO2 c gii phng ra:

2 NOHSO4 + H2O = 2 H2SO4 +NO + NO2

Phng php bung ch v xc tc NO + NO2 cho php

chng ta iu ch c axitsunfuaric c nng 60-70%.

V sau, ngi ta nhn thy bung ch khng thun li cho

qu trnh sn xut cho nn thay bung ch bng ccthp hp th c xy bng gch chu axit nn n c gi l

phng php thp m. Tuy nhin, axit sunfuric thu c

c tinh khit khng cao (do c ln nhiu HNO3 trong

qu trnh sn xut) hn na hiu sut ca qu trnh ny

cng khng ln ch vo c (60 -70 %) bi vy phng php

ny hu nh khng c s dng sn xut axit sunfuric

na.

2. Phng php tip xc :

- C 2 phng php tip xc l: tip xc n v tip

xc kp.

+ i vi phng php tip xc n: hn hp kh SO2qua gia nhit c oxy ho ln lt qua 4-5 lp tip xc. Gia

lp 1-2 dng thit b truyn nhit gin tip h nhit hn hp kh, gia lp 1-2, 3-4 b sung khng kh

lm lnh trc tip, cui cng hiu sut chuyn ho t 98,2

%. Sau hn hp kh a i hp th ch to axit (mc

chuyn ho c th ln ti 99,9 %) .

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31/57

-u im:

_Lm gim nhit tip xc,hn ch lng nhit truyn

ra mi trng.

-Nhc im:_Tn vt liu ch to thit b do c nhiu lp tip

xc,phi thng xuyn b xung khng kh,do lng O2cn s dng nhiu.

_Tri qua nhiu giai on mi thu c H2SO4 c nng

cao.

+ i vi phng php tip xc kp: chuyn kh sn

phm t sau lp tip xc 3 (hiu sut 90%) a i hp thch to axit sau gia nhit phn ng 2 lp sau nng

hiu sut chuyn ho lu tin ln 99,5 %, a i hp th

ln 2 sau phng khng. Trong phng php ny nng

CO2 trong kh thi gim t 0,21 % (phng php tip xc

n) xung cn 0,05% (phng php tip xc kp).

-u im:

_Gim ng k lng CO2 trong kh thi,dn n thu -c H2SO4 c tinh khit cao.

_Ch to thit b n gin.

Nhc im:

3. Xc tc:

C nhiu loi xc tc c th xc tc cho qu trnh oxyho SO2 thnh SO3 tuy nhin xc tc thng dng nht l

vanadi .

- Thnh phn xc tc vanadi :

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+ V2O5 l thnh phn chnh hm lng ca n khong

5-12 %

+ Mui ca kim loi kim l cht kch ng lm tng

hot tnh xc tc ln hng trm ln. T l kim loi kim vvanadi dao ng t 1:1 n 6:1.

+ SiO2 dng xp ng vai tr cht mang .

+ Ngoi ra cn mt s cht khc c a vo nhm

tng hot tnh ,tng bn c v nhit ca cht xc tc.

V d a P2O5 vo xc tc th nhit hot tnh ca xc

tc gim i 20 -250

CC ch lm vic ca xc tc ny l:

+ O2, SO2 b hp ph trn b mt xc tc v ho tan

hon ton vo xc tc nng chy s tc dng vi V2O5 theo

phng trnh:

V2O5 + SO2 = V2O4 + SO3

V2O4 + 0,5 O2 = V2O5

- Cn SiO2 lm nhim v cht mang ,c tc dng tng

b mt tip xc pha ca cht xc tc v n nh cht

hot tnh trn b mt xc tc. giai on u ca qu

trnh chuyn ho khi nng SO2 trong hn hp kh cn

cao s to thnh hp cht vanadyl sunfat:

V2O5 + SO3 + SO2 = 2 VOSO4 .

giai on cui ca qu trnh chuyn ho lng SO2cn li t nn xc tc c hot tnh cao, hng s tc k

ln.

- Tuy nhin, chng ta phi lu ti mt s tp cht gy

ra s ng c ca xc tc nh :

+ Cht c nguy him nht l As.

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Ch vi miligam asen oxit trong 1m3 hn hp kh cng

cho xc tc b ng c. Asen b hp ph trn b mt xc

tc to thnh mt lp mng che ph b mt ht xc tc

hoc to thnh vi xc tc hp cht bay hi As2O5.V2O5 tch

khi xc tc.

+ Cc hp cht ca flo cng gy tc hi ng k cho

xc tc :nh SiF4 phn ng vi hi nc theo phng trnh:

SiF4 + 2 H2O -------> SiO2 + 4 HF .

SiO2 to thnh lp v bao bc ht xc tc. Lng SiF4

cng nhiu th hot tnh xc tc cng gim nhanh.Di y l mt s thit b dng trong cng on oxi

ho SO2 .

- Thp oxi ho: thng dng loi thp oxi ho c t 4-5 lp

xc tc c truyn nhit trung gian sau mi lp xc tc. Hn

hp kh SO2 t qut kh i vo khong khng gian gia cc

ng ca thp truyn nhit ngoi. N c t nng s b

nh kh nng t thp tip xc i ra. Sau mi lp xc tcnhit ca hn hp kh tng. V vy phi cho qua cc b

phn truyn nhit h nhit xung. Sau lp xc tc

cui, hn hp kh ra khi thp tip xc v vo thit b

truyn nhit ngoi t nng hn hp kh mi, ng

th h nhit xung trc khi sang cng on hp th.

- Thit b trao i nhit ngoi

+ Thit b trao i nhit ngoi: mc ch t nngs b kh nguyn liu v lm ngui hn hp kh cha SO3sau chuyn ho .Kh nng cha SO3 i trong ng t trn

xung cn kh ngui cha SO2 i khong khng gian

gia cc ng t di ln.

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34/57

+ Thit b lm ngui SO3: v nguyn tc ging thit

b truyn nhit ngoi: SO3 i t trn xung cn khng

kh hoc nc lm ngui i t di ln.

+ Thit b t nng khi ng: khi nh my mi hotng hoc chy li sau khi dng lu ngi ta phi sy xc

tc v nng dn nhit ca thp tip xc n nhit

hot tnh ca xc tc. Mun vy phi thi khng kh nng

c nhit 450 -5000C qua thp tip xc cho n khi h

thng lm vic bnh thng. t nng c th s dng

kh l c nhit 650 -7000C, t kh thin nhin, hoc

s dng thit b t nng khng kh bng in.

V. Hp th anhydrit sunfuaric SO3

V.1 C s l thuyt ca qu trnh hp th:

H thng hp th y l h thng hp th ngc

chiu,H2SO4 thu c t qu trnh trc c i qua thit b

hp th.Sau khi i qua ng th nht,nng axit tng

1 2 3 4

SO3

(300C)

H2

OSO

3

Oleum

H2SO

4

(98,3%)

H2SO

4

(96%)

SO

3

d

H2SO

4

(98,3%)

H2SO

4

(96%)KhthiSO

2,

SO3

H2so

4

70%

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n 96%,sau ln th hai tng n 98,3%,sau ln th ba

tng n 99,7%.

- Phn ng:

n SO3 + H2O = H2 SO4 + (n-1) SO3 .+ Tu theo t l gia lng SO3 v H2O

m nng axit thu c s khc nhau:

n > 1 l sn phm l oleum.

n = 1 sn phm l monohydrat (axit sunfuaric 100%).

n < 1 sn phm l axit long.

Thng thng, ngi ta c xu hng sn xut ton b sn

phm di dng oleum bo qun vn chuyn v sdng thun li hn. Mun vy cho hn hp kh cha SO3qua thp c ti oleum. Thp oleum ch hp th c mt

phn SO3 trong hn hp kh. Hm lng SO3 cn li trong

kh ra khi thp oleum kh ln. Do hp th ht SO3li phi a hn hp tip tc qua thp hp th th hai ti

monohydrat (thp monohydrat). n y mi kt thc qu

trnh hp th SO3. y khng dng nc hp th SO3 do hm lng hp

th khng c nhiu,do ngi ta s dng oleum hp th

SO3 t hiu sut cao hn.

V.2 Thit b trong qu trnh hp th:

Kh SO3 sau khi lm ngui s b thit b truyn

nhit ngoi c a sang cng on hp th. y khSO3 tip tc c lm ngui to iu kin tt cho qu trnh

hp th. u tin SO3 c hp th trong thp oleum sau

sang thp monohydrat, cui cng qua thp tch git ri

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phng khng hoc a i thu hi SO2 + Thp hp th:

c th s dng nhiu loi thp hp th khc nhau:

- Thp m: lm bng thp lt gch chu axit bn

trong xp y m snh s. a axit vo thp, thngdng cc loi vi phun axit. Yu cu ca m ca thp

oleum khong 600-1000 m2 cho 1 tn sn phm/gi. Lng

SO3 trong thp monohydrat nhiu hn nn b mt ca

thp ny c th ti 1200 m2/tn/ gi. Do qu trnh hp th

to nhiu nhit nn va tin hnh hp th SO3 va lm

ngui ngay bn trong thp. C th s dng 2 loi thp:

- Thp hp th si bt kiu a l hoc a chp.- Thp hp th lm ngui

+ Thit b lm ngui axit :

- Thit b lm ngui kiu gin ti :

u im: lng nc lm ngui t cu to n gin, d

quan st v lm sch pha ngoi ng.

Nhc im: thit b cng knh, hiu sut s dng nc

lm ngui thp, sinh ra nhiu hi nc lm khng kh xungquanh c m cao.

- Thit b lm ngui kiu ng chm:

u im: chc chn, gn, tn t kim loi, d lm

sch pha trong ng

Nhc im: kh ch to bng vt liu khng nung v

hn c + Mt s ch tiu k thut ca cng

on hp th SO3 :

Nhit kh , 0C

Ra khi thp oleum :


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Thp oleum ,%SO3 t do 19 + (-) 1

Thp monohydrat % H2SO4 98,3 + (-) 0,4

Hiu sut hp th % > =

99,9

Nhn xt chung:

Hin nay s c in c dng ph bin nht trn

th gii nhng s ny rt phc tp v khng kinh t. V

vy nhiu vin nghin cu v x nghip trn th gii rt

ch ci tin s k thut v thit b. Mt s phng

php sn xut u vit hn c cp ti nh: phng php

tinh ch kh, thit b tip xc kiu lp si Khng nhng

vy nng sut ca cc h thng sn xut cng tng ln mt

cch ng k (nm 1982 hng Texas Gulf Inc a ra dy

chuyn nng sut 2800 tn /ngy, nm 1988 nng sut ca

hng Texas Gulf Inc l 379 000 tn/nm ). Trc y dng

thi v cht thi ca cc nh my sn xut axit sunfuaric

cha c quan tm ng mc cho nn li nhng hu

qu ng tic cho mi trng. Gn y vn nhim

mi trng c ch hn. Cc nh my, x nghip snxut c nhng bin php qun l, gim thiu, x l cc

cht thi, cc dng thi. gip mt phn cc nh my

sn xut chng ti s trnh by tip cc cht thi, dng

thi chnh ca nh my sn xut axit sunfuric.

D.1 vn mi trng ca qu trnh sn xutaxit sunfuric

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Qu trnh sn xut axit sunfuric to ra nhiu dng cht

thi khc nhau, chia thnh 3 dng chnh l:

- Kh thi

- Cht thi rn

- Cht thi lngMi dng thi ny u c nhng c trng ring khc

nhau, nhng tu chung li u nh hng rt ln ti sc khe

ca con ngi v mi trng sng.

I. kh thi :

Thnh phn bao gm: kh axit v khi bi.

1. Kh axit :

- Thnh phn: ch yu l kh SO2, ngoi ra cn c SO3 v

m H2SO4 (CO v CO2 khng phi l cht thi c trng ca

cng ngh sn xut axit sunfuric nn khng cp ti)

- Nguyn nhn: pht sinh phn ln do cc cng on: to

kh SO2, tinh ch kh SO2, cng on tip xc v qu

trnh hp th to axit sunfuric; ngoi ra qu trnh tnhin liu (than) cng to ra SO2.

1.1.c tnh ca SO2:

- SO2 l cht kh khng mu, khng mi, kch thchmnh; d ha lng, d ha tan trong nc vi nng

thp. iu kin bnh thng: 1 th tch nc ha tan

40 th tch SO2.

- SO2 rt bn nhit: H0tt = - 296,9 kJ/mol

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{1}

- SO2 thuc loi cht nhim c hi nht v ph bintrong sn xut cng nghip v trong cuc sng sinh

hot ca con ngi.

Theo bng trn: LC50= 3000ppm/30 pht

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1.2. SO2 rt c hi i vi sc khe:

+ SO2 l cht kh gy kch thch mnh ng h hp.

Khi ht th phi SO2: nng thp c th gy co tht

cc loi si c thng ca ph qun; nng cao c th

gy tng tit nhy nim mc ng h hp trn v

cc nhnh kh ph qun.

+ SO2 c th vo c th qua ng h hp hoc ha

tan vo nc bt ri vo h tiu ha ri sau phn tn

v h tun hon.

+ SO2 c th nhim c qua da gy s chuyn ha

lm gim d tr kim trong mu, o thi amoniac ra

nc tiu v kim ra nc bt.+ SO2 gy ri lon qu trnh chuyn ha protein v -

ng, thiu vitamin D v C, c ch enzym oxidaza.

+ SO2 khi b hp thu mt lng ln c kh nng gy bnh

cho h thng to huyt v to ra methemoglobin

(hemoglobin trong Huyt cu t b chuyn ha thnh

methemoglobin, do lm gim lng Huyt cu t v

kh nng chuyn ch Oxy ca cht ny trong c th; dothiu oxy, da b i thnh mu xanh)

+ SO2 nh hng ti chc nng ca phi, gy vim phi,

vim ph qun mn tnh, gy bnh tim mch, tng mn

cm nhng ngi mc bnh hen

Nh vy c th thy, SO2 l cht gy nhiu tc hi i vi

sc khe con ngi v lng SO2 ch yu b thi ra trong qu

trnh sn xut cng nghip. V vy phi c hn mc ivi lng SO2 trong kh thi (tham kho bng tiu chun d-

i)

1.3. SO2 l nguyn nhn chnh gy ra ma axit:

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- Ma axit l hin tng ma m nc ma c pH di 5,6.

- Qu trnh to thnh ma axit din ra nh sau:

+ SO2 b oxyha thnh SO3 (lu hunh trioxit). SO2 + OH HOSO2(phn ng ha hp gia lu hunh ioxit v cc hp cht gc

hidroxyl)HOSO2 + O2 HO2 + SO3;

(phn ng gia hp cht gc HOSO2 v O2 cho ra hp cht gc HO2

v SO3)

+ SO3 tc dng vi hi nc trong khng kh to cc ht

axit sunfuric:SO3(k) + H2O(l) H2SO4(l) {3}

y chnh l thnh phn ch yu ca ma axit.

- Ma axit c pht hin ln u tin vo nm 1948 tiThy in. T n nay, ngi ta thy rng ma axit

rt nguy hi trong nhiu kha cnh t mi trng ti i

sng x hi. C th l:

+ i vi thy vc (ao, h): ma axit ri trn mt t s

ra tri cc cht dinh dng, ha tan cc kim loi nng

trong t v mang cc kim loi c xung thy vc. Cc

dng chy do ma axit vo thy vc, do lm pH

ca h, ao gim i nhanh chng. Cc sinh vt trong thy

vc khng kp hoc khng th thch ng c vi iukin mi trng , v vy chng s b suy yu hoc

cht hon ton.

nh hng ca pH i vi h thy sinh vt tm tt

nh sau: (*)

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pH Tc ng ln h thy sinh vt5,5


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Hn na, khng phi ton b SO2 trong kh quyn u -

c chuyn ha thnh axit sunfuric, mt phn ca n c th

lng ng tr li mt t di dng kh SO2. Khi tip xc

vi l cy, n s lm tt cc th soma ca l cy gy cn

tr qu trnh quang hp. V li, cng do hin tng tch t

sinh hc, c t i qua thc vt vo chui thc n cui

cng cng c th gy c cho con ngi.

+ i vi kh quyn: cc ht sunphat to thnh trong kh

quyn dng m, lm hn ch tm nhn. Sng m axit cng

lm gim kh nng lan truyn nh sng mt tri. Trn mt

khu vc rng tc hi ca n l kh ln.

+ i vi cc cng trnh xy dng v cc loi vt liu: nng

axit trong ma axit c kh nng n mn cc loi vt liu

khc nhau nh: vi si, kim loi, do nh ca v cc cng

trnh (cu, tng iu khc..) s b n mn. c, trang

thit b, phng tin giao thng, cng d b ph hy kt

cu khi tip xc vi ma axit. Mt v d: ta nh Capitol

Ottawa b tan r bi hm lng SO2 qu cao.

Tm li, ma axit, vi thnh phn to thnh chnh l SO2,

gy ra nhiu tc hi trn nhiu lnh vc ca i sng x

hi v mi trng.

Vy : SO2, vi tc hi th nht l kh nng gy nguy himvi sc khe ca n, trc ht nh hng trc tip ti nhng

cng nhn lm vic trong nh my sn xut axit sunfuric.

Trong mi trng lm vic , ngi cng nhn rt d mc

bnh ngh nghip lin quan n h hp. Tc hi th hai,

nguy him khng km, bi s d pht tn trn din rng

ca ma axit. Cc nh my thng lm ng khi cao a

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kh thi ln cao. Chnh iu ny li d lm cho kh thi

pht tn ti mt khu vc rng ln, c khi xa nh my.

2. Bi:

- Nguyn nhn: pht sinh t cc qu trnh chun b

nguyn liu (gia cng kch thc nh), vn chuyn nguyn

liu. Ngoi ra trong qu trnh t nhin liu, khi l thot

ra ngoi cng em theo cc ht bi x.

- Lng bi trong khng kh ph thuc vo cc loi qung,

kch thc ht x, cu to l t.

- Phn loi bi: da vo kch thc ht bi ngi ta chia

thnh:

+ Bi ton phn (TSP Total Suspended Particulate)

+ Bi PM10 (PM Particulate Matter) c ng knh kh

ng hc di 10 micron.

Hu ht nhng ht bi c ng knh 5-10 xm nhp va

lng ng ng h hp gia.

+ Bi h hp l nhng ht bi c ng knh kh ng

hc di 5 micron, c th xm nhp su n tn cc ph

nang l vng trao i kh ca h thng h hp.

- Tc hi: + Do nhng c im trn, bi nh hng rtln n sc khe con ngi, c bit l ngi dn sng

xung quanh nhng nh my, c s sn xut pht sinh

nhiu bi. V trc mt l nhng ngi cng nhn trc

tip lm vic trong dy chuyn.

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+ Ngoi ra, khi bi trong khng kh bm ln l

cy, s ngn cn dn n lm gim hot ng quang hp.

Lm cy b ci cc, c th cht.

II. cht thi rn

- Thnh phn ch yu l

+ cc loi x qung t cc l t qung, cha

cc loi oxit nh oxit st v oxit tp cht khc

+ qung ri vi trong qu trnh vn chuyn

nguyn liu (nu khng c che chn k)

+ trong qu trnh sn xut c s dng mt s

loi cht xc tc. Nhng cht ny ch s dng c trong

mt thi gian, sau chng tr nn tr, gim hoc

khng cn kh nng xc tc. V vy chng s b thi ra

ngoi nh mt loi cht thi rn. Trong cc cht xc tc

c V2O5, l mt cht rt c, lm mt b sng ty, rt mi,

c hng, nh hng ti h thng h hp.

+ do c im mi trng sn xut axit, d b

r r cc kh axit v m axit nn cc my mc trang thit

b trong nh my rt d b n mn, phi c thay th.

y cng l mt ngun cht thi rn ln.

- Tc hi:

+ cht thi rn thng b ra ngoi hoc chn lp,

vi c im l cha kim loi nng trong x, kh

chng s i vo mi trng, gy nh hng ti cc loi sinh

vt v c con ngi qua s trao i dinh dng. Ngoi ra,

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trong cht thi rn cn mt lng qung ri vi, qung

ny cha mt lng lu hunh v nhng cht khc, gy

bnh tt cho con ngi. Mt s vng gn nh my sn xut

axit sunfuric c nhiu ngi b bnh. V d nh s xut

hin ca nhng lng ung th nh Thch Sn. Tuy cha c mt

kt lun chnh xc t pha cc nh khoa hc, nhng rt

kh ph nhn s nh hng ca cc cht nhim t

nh my sn xut cng nghip, c bit l cng nghip

ha cht n sc khe ca dn c xung quanh.

+ Do sn xut lin tc, lng cht thi rn s ngy cng

nhiu thm, v vy cng lm tn cc din tch t chn lp, v nhng din tch t ny cng t an ton

cho vic s dng vo bt c mc ch g sau . Do ,

cht thi rn nh hng ln ti cc vn ca cng ng

nh sc khe, t ai.

III. cht thi lng

Thnh phn gm:

- Nc thi:

+ do r r kh axit trong mt s cng

on ni trn, ngi ta thng s dng nc hp th, to

thnh nc thi cha mt lng axit nht nh.

+ ngoi ra, lng kh b r r s bm vobi m, to thnh cc ht axit, ri xung sn, bm vo b

mt dng c, c. Dng nc lau ra sn nh hay

cc c ni trn cng to ra nc thi c tnh axit.

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+ nc lm mt axit trong cng on hp

th to axit sunfuric cng l mt dng nc thi.

+ nc ma khi ri xung khu vc sn xut

s mang theo cc ht bi, x, qung, axit, v cng thamgia vo lng nc thi ca qu trnh sn xut.

- Cht thi lng khc nh: du m trong bo tr, sa

cha my mc,

- Tc hi: do c tnh axit, ty nng khc nhau, nu

nc thi khng c x l hoc x l khng tt, khi b

thi ra mi trng s trc tip nh hng ti h thy sinh vt(tham kho bng (*)). Nc thi ra sng c th lm

cht thy sn ca ngi dn nui di ngun, bnh v da

cho nhng ngi s dng nc trong sinh hot. Cha k

nhng loi tp cht khc trong nc thi nh: kim loi nng,

du m, i vo trong c th sinh vt. Tc hi khn lng.

D.2 Mt s Gii php gii quyt vn nhim

I. V kh thi:

1. SO2:

- Nguyn nhn r r kh l:+ do hiu sut chuyn ha thp

+ ch chy ca l t

+ loi l t

+ ch lm vic

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+u im: r tin, d tm, d hon nguyn

+Nhc im: do ha tan ca SO2 trong nc

thp nn phi cn lu lng nc ln v thit b hp th c

th tch qu ln, qu trnh hp th tn nhiu nng l-

ng chi ph nhit ln

-Hp th bng huyn ph CaCO3 sa vi:

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CaCO3 + SO2 = CaSO3 + CO2

CaO + SO2 = CaSO3

2CaSO3 + O2 = 2CaSO4

+u im: quy trnh n gin, chi ph hot

ng thp, cht hp th d tm, c kh nng x l

m khng cn lm ngui v x l s b, khng chim

nhiu din tch xy dng+Nhc im: thit b ng cn do to thnh

CaSO4 v CaSO3, gy tc cc ng ng v n mn thit

b

Ngoi ra, SO2 cn c hp th theo phng php Magie,

phng php Zn,

phng php amoniac, hn hp mui nng chy

* Phng php hp ph:

- cht hp ph l vi, lmit, vi

+u im: to ra hiu sut hp ph cao (90%)

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+Nhc im: cn chi ph u t ln do vt liu

ch to thit b t

- cht hp ph l than hot tnh

S dng cc phng php trn, ngoi lng SO2 c thu hi,

cng gip thu hi lun lng CO2 trong kh thi.

2. M H2SO4 v SO3 trong kh thi:

- Nguyn nhn r r:

+ do hiu sut hp th thp

+ kiu thp hp th

+ m trong nguyn liu v trong pha kh

+ nng , nhit axit ti

Gii php:+ la chn thp hp th kiu m

+ la chn loi m ph hp

+ c phng php kh m

+ x l kh thi: ch yu bng hp th hochp ph

3. Bi: bin php x l ch yu l thu hi bi trong khthi. C 2 phng php x l chnh l:

* Phng php c hc: tch bi khi dng kh da vo lc

trng trng v lc li tm ca ht bi. Ty kch thc ht bi

c th s dng cc phng php khc nhau.+ phng lng l thit b trong ht bi

lng di tc dng ca trng lc, phng lng ch lng c

bi ln

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+ thit b lng bi c hc c dng ph bin

l xyclon, bi lng c l do tc dng ca lc li tm (hiu

sut c th ti trn 90%)

* Phng php lc in:

- u im: + tch c nhng ht bi rt nh, hiu

sut tch bi t ti trn 99%

+ lm vic c trong mi trng nhit

cao v n mn ha hc

+ c th t ng ha hon ton qu

trnh lm sch kh

X l bi l mt trong nhng bin php x l cn thit

trc nht v n nh hng ngay trc tip n mi trnglm vic ca cng nhn.

D bng bt c phng php no, kh thi thot ra t nh

my sn xut cng nghip ni chung v axit sunfuric ni

ring phi t c mc tiu chun qui nh:

- Theo TCVN 5939:2005, gii hn ti a cho php ca cc

cht v c trong kh thi cng nghip thi ra mi trngxung quanh l:

n v tnh: mg/Nm3 (miligam trn 1m3 kh thi chun)

Tiu chun Gii hn ti aA B

Bi khi 400 200SO2 1500 500H2S 7,5 7,5

Hi H2SO4 hoc SO3, tnh

theo SO3

100 50

Mc A: p dng cho cc nh my, c s ang hot ng

Mc B: p dng cho cc nh my, c s xy dng mi

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m3 kh thi chun c tnh l 1 khi kh O0C v p sut

tuyt i l 760mmHg

II. V cht thi rn:

i vi cht thi rn, bin php ch yu l thu gom, tn

thu, ti s dng, sao cho nng cao nng sut s dng, hn

ch ti a s pht thi. Phn cn li, nhng cht thi rn

bt buc b thi ra, c th c x l bng mt s phng

php sau (qu trnh x l ny thng khng phi ca nh

my sn xut axit sunfuric)

- Phng php c hc, gm: +phng php p+phng php ct

+phng php nghin

+phng php sng

+phng php tuyn

- Phng php ha-l: dng x l, thu hi nhng cht

ha hc c hi cho c th con ngi v cho mi trng, cth c:

+ hp th

+ hp ph

+ kt ta

+ oxi ha

+ c nh v ha rn

- Phng php nhit-c:+ to khi: s dng nhit cao nhm

chuyn cc cht thi rn thnh nhng dng mi c th s

dng nh vt liu xy dng (gch,)

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- Phng php sinh hc: dng x l cc cht thi rn hu

c.

III. Nc thi:

- Nc lm mt axit c th c gii quyt nh sau (vi mc

ch gim thiu lng nc thi, ti s dng nc thi):

+ tun hon nc lm mt

+ thay i s lm mt ( nng

cao hiu qu s dng)

+ thay i s lm mt

- Ton b lng nc thi t nh my thi ra cn c x lbng cc phng php khc nhau c th t tiu chun

thi ra mi trng. Mt s phng php x l nc thi l:

* Phng php c hc: dng loi b cc cht rn l lng

trong nc thi. y l giai on x l s b.

- phng php ch yu l: lc qua li, lng, lc qua

vt liu ct v quay li tm, Lng cht lng thu c cng

tr thnh mt dng cht thi rn.* Phng php ha-l: s dng cc hin tng v phn ng l

ha thu hi hoc kh i cc loi c cht nguy him

- phng php thng s dng l: oxi ha, trung ha

(dng kim,..), keo t, tuyn ni, mng bn thm

* Phng php sinh hc: thng loi b cc hp cht hu

c trong nc nh da vo c tnh sng ca cc loi thc

vt, vi sinh vt, chng s dng cht hu c lm ngundinh dng. Phng php ny thng l cng on x l cui

cng.

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Nc thi sau khi x l phi t c nhng gii hn xc nh

c qui nh nh sau:

- Theo TCVN 5945:2005, gi tr gii hn cc thng s

v nng mt s cht nhim trong nc thi cng

nghip l:

Thng s n v Gi tr gii hnA B C

Nhit 0C 40 40 45pH - 6 n

9

5,5

n 9

5 n

9Mi - Khng

khchu

Khng

khchu

-

Cht rn l lng mg/l 50 100 200St mg/l 1 5 10Du m khong mg/l 5 5 10Sunfua mg/l 0,2 0,5 1Xt nghim sinh hc

(bioassay)

- 90% c sng st

sau 96 gi

trong 100% nc

thi

-

Gi tr thng s mc A: c th vo cc thy vc th-

ng dng lm ngun nc cho mc ch sinh hot

Mc A< Gi tr thng s mc B: c th vo cc thy

vc nhn thi khc tr nhng thy vc trn.

Mc B< Gi tr thng s mc C: ch c php thi vonhng ni c qui nh (nh h cha nc thi c xy

ring, cng dn n nh my nc thi tp trung,)

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Ti liu tham kho:

1. http://en.wikipedia.org/2. nh hng ca nhim khng kh i vi s khe cngng, TS Nguyn Duy Bo, ThS inh Xun Ngn, Vin Yhc lao dng v v sinh mi trng.

http://www.nea.gov.vn/tapchi/toanvan/08-2k7-22.htm3. TCVN 5939:2005; TCVN 5945:2005

4. http://vi.wikipedia.org/wiki/

56
http://en.wikipedia.org/http://www.nea.gov.vn/tapchi/toanvan/08-2k7-22.htmhttp://vi.wikipedia.org/wiki/http://en.wikipedia.org/http://www.nea.gov.vn/tapchi/toanvan/08-2k7-22.htmhttp://vi.wikipedia.org/wiki/


57/57

5.http://www.ctu.edu.vn/colleges/tech/bomon/ttktmoitruong/Giaotrinh/mrviet/

6.nh gi quan h gia cng ngh sn xut v mi trngmt cch tip cn mi trong kim sot mi trng cngnghip, GS.TS ng KimChi, tuyn tp bo co khoa hcK nim 10 nm thnh lp Vin KH&CN mi trng, HBKHN7. Chuyn : Cng ngh x l kh SO2, ThS inh Hi H

8. Ho k thut i cng Phng Tin t - Trn Th Bnh-NXB i hc s phm-20049.http://www.vinacomin.vn/wm/public/vinacomin_func.jsp?cgiMain=encryptMAIN_LVKD&cgiiFunc=encrypt12/

10.http://www.vimicovn.com/gioithieu/danhsachcacmo.htm

11. http://vi.wikipedia.org/wiki/Sulfur/

12. Giao trinh hoa ki thuat dai cuong,NXBDHSPKT
http://www.ctu.edu.vn/colleges/tech/bomon/ttktmoitruong/Giaotrinh/mrviet/http://www.ctu.edu.vn/colleges/tech/bomon/ttktmoitruong/Giaotrinh/mrviet/http://www.vimicovn.com/gioithieu/danhsachcacmo.htmhttp://vi.wikipedia.org/wiki/Sulfur/http://www.ctu.edu.vn/colleges/tech/bomon/ttktmoitruong/Giaotrinh/mrviet/http://www.ctu.edu.vn/colleges/tech/bomon/ttktmoitruong/Giaotrinh/mrviet/http://www.vimicovn.com/gioithieu/danhsachcacmo.htmhttp://vi.wikipedia.org/wiki/Sulfur/

Cong Nghe San Xuat AXIT SUNFURIC(1)

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