Chng 1: Tng quan Axit SunfuricI. Tng quan v sn phm:1. Tnh cht ca Axit Sunfuric v Oleuma. Khi nim chung Trong ho hc, axit Sunfuric c xem l hp cht ca Anhydrit Sunfuric vi nc. Cng thc ho hc: H2SO4 hoc SO3.H2O, khi lng phn t 98,08Trong k thut th hn hp theo t l bt k ca SO3 vi nc u gi l Axit Sunfuric. Nu t l SO3/H2O 1 gi l Oleum Thnh phn ca dung dch axit sunfuric c c trng bi phn trm khi lng ca H2SO4 hoc SO3V d: axit sunfuric c nng 98% hoc 80% SO3Nng ca Oleum c tnh bng phn trm SO3 t do (trn 100% H2SO4) hoc % SO3 tng. i khi cn tnh bng % H2SO4 (lng H2SO4 thu c khi thm nc vo oleum)V d: oleum nng 20% SO3 t do hoc 85,3% tng hay 104,5% H2SO4b. Mt s tnh cht ca Axit Sunfuric v OleumAxit sunfuric khan l cht lng khng mu, snh (khi lng ring 20oC l 1.8305 g/cm3), kt tinh 10,07oC. p sut thng (760 mmHg) n 296,2oC axit sunfuric bt u si v b phn hu cho ti khi to thnh hn hp ng ph cha 98,3% H2SO4 v 1,7% H2O. Hn hp ng ph ny si 336,5 oC.Axit sunfuric c th kt hp vi nc v SO3 theo t l bt k, khi to thnh mt s hp cht c nhng tnh cht khc nhau. Nhit kt tinhDung dch c nng bt k ca axit sunfuric v oleum u c th xem l hn hp ca 2 dung dch trong cc hp cht sau:Bng 1: Nhit kt tinh ca cc hp cht gia H2O v SO3TTCng thcHm lng, %Nhit kt tinh, oC

H2SO4SO3 tngSO3 t do

1H2O00,0-0

2H2SO4.4H2O57,646,9--24,40

3H2SO4.2H2O73,259,8--39,60

4H2SO4.H2O84,569,0-8,48

5H2SO410081,6-10,37

6H2SO4.SO3110,189,944,9538,15

7H2SO4.2SO3113,993,062,01,20

8SO3122,5100,0100,016,80

Nhit si v p sut hiKhi tng nng , nhit si ca dung dch axit tng, t cc i (336,5oC) 98,3% H2SO4, sau gim.Khi tng hm lng SO3 t do, nhit ca oleum gim t 296,2oC ( 0% SO3 t do) xung 44,7oC ( 100% SO3 tc nhit si ca SO3).Khi tng nng , p sut hi trn dung dch gim, t cc tiu 98.3% H2SO4, sau li tng. p sut hi trn oleum tng khi hm lng SO3 t do. C th tnh p sut hi trn dung dch axit sunfuric v oleum theo cng thc sau:lgP = A-B/T (1.1)Trong : P_p sut hi, mmHg A, B_ cc h s ph thuc nng axit v oleum nh sau:

% H2SO42040608098,5100

A8,9228,8448,8419,2939,7809,805

B226822992458304042113944

% SO3 t do510203065100

A8,519,019,8410,4410,509,89

B275028122915296525102230

Ni chung, hi trn dung dch axit v oleum c thnh phn khc vi thnh phn pha lng.V d: hi trn dung dch axit sunfuric long ch yu l hi nc, cn hi trn oleum phn ln li l SO3. Ch trn dung dch 98,3% H2SO4, thnh phn pha hi mi bng thnh phn pha lng.Nh vy, khi un nng dung dch axit sunfuric long hoc oleum th sn phm cui cng l axit 98,3% H2SO4 ch khng phi axit 100% H2SO4. Khi lng ringKhi tng nng , khi lng ring ca axit sunfuric tng, t cc i sau gim. Khi tng hm lng SO3 t do, khi lng ring ca oleum cng tng, t cc i 62% SO3 t do, sau gim. Khi tng nhit , khi lng ring ca axit sunfuric v oleum gim.Trong k thut thng hay xc nh nng axit sunfuric bng cch o khi lng ring ca dung dch . Tt nhin, nu trong dung dch c ln nhiu tp cht hoc nu dung dch c nng ln hn 95% H2SO4 th phng php trn khng chnh xc. Khi phi xc nh nng bng phng php ho hc. Nhit dungKhi tng nng , nhit dung ca dung dch axit sunfuric gim. Ngc li khi tng hm lng SO3, nhit dung ca oleum li tng. Khi tng nhit , nhit dung ca axit sunfuric v oleum tng. nht nht nh hng rt ln n tr lc ca axit khi chy trong ng ng hoc mng dn, n tc truyn nhit khi un nng hoc lm ngui axit , n tc ho tan cc mui, cc kim loi v cc cht khc vo axit.V vy n c s dng kh nhiu trong cc tnh ton k thut. nht ca dung dch axit vo oleum c gi tr cc i nng 84,5% H2SO4; 100% H2SO4; 50-55% SO3 t do. Khi tng nhit nht ca axit gim kh nhanhV d: khi tng nhit t 20-80oC, nht ca dung dch axit 60% H2SO4 gim i 3 ln. Nhit to thnhHiu ng nhit ca phn ng to thnh axit sunfuric v cc hp cht trung gian 25oC (298oK) c gi tr nh sau:TTPhn ngq, Kj/mol

1S tinh th hnh thoi + O2 SO2297,322

2SO2 + 0,5O2 SO3 kh96,144

3SO3 kh SO3 lng39,805

4SO3 kh + H2O hi H2SO4 hi124,988

5H2SO4 hi H2SO4 lng50,196

6H2O hi H2O lng44,079

Ch : xc nh hiu ng nhit ca cc phn ng trn nhit khc 298oK, phi tnh lng nhit cn thit t nng hoc lm ngui cc cht ban u v sn phm t 298oK n nhit .Nhit to thnh dung dch axit khc nhau (tc l lng nhit to thnh khi thm 1kg SO3 to thnh axit ) c th tnh gn ng theo phng trnh thc nghim sau:H = (1.2)Trong : H_nhit to thnh axit sunfuric, kJ/kg SO3 M_lng nc trong axit, kJ/kg SO3M = (1.3)C_Hm lng SO3 trong axit, % Nhit pha long v nhit hn hp:Nhit pha long l lng nhit t ra khi thm nc vo axit. Nhit pha long axit sunfuric t nhit ban u C1 xung nhit C2 c th tnh nh hiu ca nhit to thnh cc axit . Qf = H = H2 H1 (1.4)Khi hn hp cc axit c nng khc nhau cng to ra mt lng nhit gi l nhit hn hp, xc nh theo cng thc:Qh = H2 + 2113 H1 H2, kJ/kg SO3 (1.5)Vi: H1, H2, H3_ nhit to thnh cc axit ban u c nng C1, C2, v nhit to thnh dung dch axit cui C3 (theo 1.2)Nhit pha long v nhit hn hp cc axit c nng khc nhau c xc nh theo biu thc:Qh = Q3(m1 + m2 Q1m1) Q2m2, kJ/kg SO3 (1.6)Q1, Q2, Q3 nhit pha long v hn cc axit ban u c nng C1, C2, v nhit to thnh dung dch axit cui C3m1, m2 lng axit em hn hp, kg H2SO4 Nhit pha long (hoc c c) vi phnL lng nhit to ra khi thm mt lng nh H2O hoc SO3 vo axit sunfuric (hoc oleum) lm nng ca chng thay i rt t. Cc s liu ny ch yu dng tnh lng nhit to ra khi hp th SO3 trong cc thp hp th oleum v monohydrate hoc khi hp th hi nc trong cc thp sy (nng dung dch axit sunfuric v oleum sau khi hp th ch thay i 0,5 1,0%).Nhit to ra khi hn hp SO3 vi nc to thnh oleum c nng bt k xc nh theo phng trnh:Qh = Q100 Qo (1.7)Trong : Q100_nhit pha long v hn SO3 100%, kJ/mol SO3 Qo_ Nhit pha long oleum to thnh, kJ/mol SO3Nhit pha long oleum: Qphl = Q1 Q2 (1.8)Q1, Q2_nhit pha long v hn oleum c nng u v cui, kJ/mol SO3 xc nh theo bng sau:Bng 1.2: Nhit pha long v hn ca oleum 18oC% SO3 t do020406080100

kJ/mol SO392,2108,5125,3142,7160,9181,1

Nhit bay hiNhit bay hi nc t dung dch axit sunfuric c nng bt k c th xem nh tng nhit pha long axit v nhit bay hi nc nhit cho:Qbh = m(Q1 Q2) + L.b (1.9)Trong : m_lng H2SO4 trong dung dch ban u Q1, Q2_nhit pha long axit 100% H2SO4 xung nng u C1, cui C2 tnh theo phng trnh (1.4) L_nhit bay hi nc nhit cho, kj/kg b_lng nc bay hi, kgTng t c th tnh nhit bay hi SO3 t oleum nh sau:Qbh = mQ1 (m m1)Q2 m1Q3 + m1q (1.10)Q1, Q2, Q3_nhit pha long v hn oleum u, cui v SO3 100% kJ/mol SO3m_lng SO3 trong oleum u, molm1_lng SO3 bay hiq_nhit bay hi 1 mol SO3 lng, kJ/mol2. Tnh cht ca SO2 v SO3a. Anhydrit sunfur SO2Anhydrit sunfur SO2 khi lng phn t 64.066, nhit thng l cht kh khng mu, c mi sc c trng, khch thch mnh vi mt v c quan h hp. SO2 d ho lng ( nhit thng nhit ho lng l -10,1oC)Anhydrit sunfur SO2 tan nhiu trong nc : 20oC, mt th tch nc c th ho tan 40 th tch SO2. ho tan ca SO2 trong dung dch Sunfuric cn nh hn trong nc. Khi tng nng axit sunfuric, u tin ho tan ca SO2 gim, t cc tiu 85oC sau li tng.Khi kt hp vi nc, SO2 to thnh dung dch axit sunfur:SO2 + H2O = H2SO4H2SO4 ch tn ti trong dung dchKhi tc dng vi Clo, SO2 to thnh sunfurin clo:SO2 + Cl2 = SO2Cl2Trong cc phn ng ho hc, SO2 va l phn ng kh, va l phn ng oxi ho.b. Anhydrit sunfric SO3Anhydrit sunfric SO3 khi lng phn t 80,056 - iu kin thng l cht kh khng mu. Trong khng kh n phn ng mnh vi hi nc to nn nhng git axit nh l lng gi l m axit. 44,75oC SO3 kh bin thnh cht lng khng mu.SO3 c 3 dng th hnh: c nhit nng chy tng ng 16,8; 31,5 v 62,2, trong dng a c thnh phn l SO3, cn cc dng khc chng qua sn phm ca qu trnh trng hp SO3. Cc dng khc nhau v mng li tinh th, p sut hi, hot tnh ha hc v cc tnh cht khc. Khi t nng cc dng s b phn ly thnh SO3.SO3 phn ng mnh lietj vi nc v to rt nhiu nhitSO3 (kh) + H2O (lng) = H2SO4 (lng) + 131,1 kJSO3 l cht oxi ho c kh nng ht nc rt mnh, gy nn hin tng cacbon ho ng thc vt. Khi oxi ho S, P, CnHmSO3 b kh n SO2. Cc dng cao phn t ca SO3 () th ngc li, rt tr v ho hc kh nng phn ng vi nc rt yu.SO3 lng hn hp vi SO2 theo t l bt k.SO3 rn ho tan trong SO3 lng nhng khng to thnh hp cht ho hc.SO3 kh tc dng vi HCl to thnh axit closunfonic SO2(OH)Cl

3. Bo Qun v vn chuyn Axit Sunfuric:a. Bo qun:Sn xut Axit sunfuric l mt qu trnh lin tc, v vy sn phm phi lin tc a v khoa. kho, axit sunfuric c cha trong cc thng ln c mi che trnh bi.Thng cha axit l nhng hnh tr ng hoc nm, lm bng thp tm, dung tch 3000 m3 . Dung tch chung ca cc thng phi m bo cha c lng axit do phn xng sn xut ra trong 10 ngy. Thng mi kho c vi thng tin cho vic sa cha, v sinh,Cc thng cha axit m c v oleum khng cn phi xy lt bn trong. Ring axit tinh khit v axit long phi lt bng gch chu axit . Ti kho thng c cc thng trn pha axit theo yu cu.Vn chuyn: vn chuyn khi lng ln axit i xa, thng dng cc toa thng ng st, dung trng ti 60 tn. Khi vn chuyn lng nh c ly gn th dng t xitec, thng cha khong 0,2 1 tn, chai thu tinh 30- 45 lt. Axit acqui v axit tinh khit thng ng chai 1 lt.4. ng dng: Axit sunfuric c dng rng ri trong nn kinh tt quc dn. i vi Cng nghip ho hc axit sunfuric c dng sn xut phn ln, cc axit v c (axit photphoric, hiro floric, boric), mui sunfat ca cc kim loi khc nhau, trong sn xut thuc nhum, cc cht mu v c v nhng hp cht khc. Mt lng ln axit, c bit dng oleum , c dng trong cng nghip hu c, thuc nhum aniline, cc vt liu v si tng hp. Axit sunfuric cn c dng lm mi trng ht nc nh dung dch axit nitric, sy kh, sn xut cht n. Ngi ta dng axit sunfuric lm sch cc sn phm du la v cc sn phm thu c t nha than .Trong luyn kim mu, axit sunfuric c dng trong ch bin thu luyn, trong cng nghip gia cng kim loi dc dng lm sch mn oxit trn b mt kim loi v trong nhiu lnh vc cng nghip khc.5. Tnh hnh sn xut tiu th axit ti Vit Nam v th gii:Axit sunfuric l mt trong nhng sn phm c sn lng ln nht trong cng ngh ho hc. Trn th gii hng nm sn xut trn 46 triu tn. M hng nm sn xut hng triu tn i t kh thi. Sn lng axit sunfuric tng nhanh do cc nghnh cng nghip pht trin mnh.

Source:http://onmilwiki.com/predictions/predictionsforyrofthepigfor20142018.html Vit Nam c nhng nh my sn xut axit sunfuric: Nh my Suppe pht pht Lm Thao (tnh Vnh Phc) Nh my suppe pht pht Long Thnh (tnh ng Nai) Nh my ho cht Tn Bnh (Tp. H Ch Minh)

Bng ?: Tng trng axit sunfuric ca Vit Nam (tn/nm)

NmMin NamMin Bc

198512.000180.000

199252.000240.000

200168.547214.000

II. Cc Phng php cng ngh sn xut:Th k XVIII axit sunfuric c iu ch vi lng nh bng phng php nhit kim sunfat st (kuparos st). Nhng hin nay phng php ny khng c dngNgy nay sn xut axit sunfuric theo 2 phng php chnh: Nitroz tn ti hn 200 nm. Tip xc, mi a vo sn xut cui th k XIX Sn xut H2SO4 c cc giai on chnh sau: t chy nguyn liu cha S thu SO2 Oxy ho SO2 thnh SO3 Cho SO3 hp th nc thnh H2SO4 Trong 3 giai on ny th qu trnh oxi ho SO2 thnh SO3 trong iu kin bnh thng xy ra rt chm chp. V vy tng tc qu trnh phi dng cc cht xc tc. Cn c vo qu trnh s dng cht xc tc no a ra 2 phng n sn xut axit sunfuric. Phng php Nitoz Phng php tip xc

1. Phng php Nitroz:Phng php ny s dng cht xc tc l cc oxyt Nit Theo phng php Nitroz, qu trnh oxi ho SO2 c tin hnh trong pha lng v thc hin trong cc thp m. V vy, phng php ny gi l phng php thp.Phng trnh tng qut ca phng php thp nh sau:SO2 + NO2 + H2O H2SO4 + NOBn cht ca phn php ny nh sau: Khi t qung cha S th thu c ioxyt lu hunh cha 9% SO2 v 9-10% O2. Kh SO2 c lm sch t ht qung thiu v a vo h thng thp m (khong 4-7 thp).Thp m lm vic theo nguyn tc y l tng v theo ch a nhit. Nhit kh ra khi thp u khong 350oCTrong cc thp xy ra mt lot cc qu trnh hp th v nh hp th. Cc qu trnh ny phc tp thm v cc chuyn ho ho hc.Trong 2-3 thp u lp m c ti bng nitroz (trong nitroz c cc oxit ho tan lin kt ho hc dng notrozylsunfuric NOHSO4). nhit cao notrozylsunfuric thu phn theo cc phng trnh sau:2NOHSO4 + 2H2O 2H2SO3 + N2O3 Q (?)Lu hunh ioxyt hp th vo nc to thnh axit sunfur:SO2 + H2O H2SO3 + QAxit sunfur li tc dng vi oxyt nit trong pha lng:H2SO3 + N2O3 H2SO4 + 2NO + QMt phn SO2 c th oxi ho trong pha kh:SO2 + N2O3 SO3 + 2NO + QKh SO3 hp th nc to thnh axit sunfuric:SO3 + H2O H2SO4 + QOxyt nit nh hp th trong pha kh v oxi ho n ioxyt nit bng oxi c trong khng kh:NO + O2 2NO2 + QCc oxyt nit c hp th bng axit sunfuric trong 3-4 thp tip theo phn ng ngc ca phn ng (?). tin hnh phn ng ngc ny ngi ta s dng axit sunfuric c lm lnh v c cha mt lng Nitroz nh chy ra t thp u. Khi hp th cc oxyt s to ra axit nitrozylsunfuric tham gia trong phn ng. Nh vy oxyt nit hon thnh mt chu k kn v trn l thuyt n khng b tiu hao i. Trong thc t qu trnh hp th khng th xy ra hon ton nn s c tn tht nit oxyt.Tiu tn Nit oxyt tnh theo HNO3 l 10 20kg/tn monohydrate H2SO4Bng phng php nitroz ngi ta nhn c axit c ln nhiu tp cht v nng ch t 75-77%. Axit vi nng nh vy c s dng trong cng nghip phn bn.2. Phng php tip xc:Theo phng php ny, qu trnh oxi ho SO2 thnh SO3 c tin hnh trn cc khi xc tc rnPhng php ny hon thin hn nn gi thnh ca axit sunfuric H2SO4 sn phm c nng 92-95% tng khng ng k so vi phng php thp. Hin nay, hn 80% axit sunfuric trn th gii sn xut theo phng php ny. Di y s nghin cu k phng php tip xc sn xut H2SO4.Bng phng php tip xc ngi ta sn xut mt lng ln axit H2SO4, trong c c oleum cha 20% SO3 t do, du Kuporos (92,5% H2SO4 v 7,5% H2O), axit acqui c thnh phn tng t du Kuporos nhng sch hn.Phng php tip xc chia thnh 3 giai on: t nguyn liu cha S thu SO2 v lm sch kh SO2 Oxi ho tip xc SO2 thnh SO3 Hp th SO3 thnh axit H2SO4 Quan trng nht l giai on 2 v theo n ngi ta nh ga ton b phng php. 2.1 . Ch to kh SO2 v lm sch2.1.1. Nguyn liu:2.1.1.1. Qung Pyrit: Qung Pyrit thng:Thnh phn ch yu ca qung l st sunfua FeS2 cha 53,44% S v 46,56% Fe thng dng tinh th Pyrit hnh lp phng (khi lng ring 4,9-5,0 g/cm3), cng c khi dng macazit hnh thoi (khi lng ring 4,55 g/cm3). 450oC macazit chuyn thnh Pyrit c t a nhit.Qung Pyrit thng gp l mt loi khong mu vng xm, khi lng ng khong 2200-2400 kg/m3 tu theo kch thc ht qung. trong qung c laanxx nhieeuff tp cht nh tp cht ca ng (c yu l FeCuS2, Cu2S, CuS), ch, km, niken, bc, vng, coban, selen, telu, silic; cc mui cacbonat, sunfat canxi,magie, V vy, hm lng thc t ca S trong qung dao ng trong khong t 30-52%Ngoi ra cn thy loi hp cht ca lu hunh v st c thnh phn phc tp hn nh: FenSn+1 (n>4 ) gi l pyrotin hay pyrit t.Qung pyrite c nhiu Nga, Ty Ban Nha, Nht Bn, Canada, min bc nc ta mi ch pht hin mt s m pyrit, nhng ni chung hm lng lu hunh thp (khong 20-30% S), tr lng khng ln lm. Pyrit tuyn niTrong qung Pyrit c rt nhiu tp cht, mt trong hng tp cht c gi tr l ng. Nu hm lng pyrite trong ng ln hn 1% th em qung ny ch bin ng c li hn l t trc tip sn xut axit sunfuric.Trc khi em luyn ng, thng dng phng php tuyn ni lm giu ng ca qung ny ln khong 15-20% Cu (gi l tinh qung ng). Phn b thi cu qu trnh tuyn ni cha khong 32-40% S gi l qung pyrite tuyn ni, dng sn xut axit sunfuric tuyn ni. C tuyn 100 tn qung thu c 15-20 tn tinh qung ng v 80-85 tn pyrite tuyn ni. Nu tin hnh tuyn ln hai s thu c tinh qung pyrite cha ti 45-50% S.Qung pyrite c kch thc rt nh (khong 0,1mm) v m kh ln (12-15%) gy kh khn cho qu trnh vn chuyn v t. v vy trc khi s dng phi sy gim hm lng m xung. Pyrit ln thanThan mt s m c ln c qung pyrite, c loi cha ti 3-5% lm gim cht lng ca than. V vy phi loi b nhng cc than c ln pyrite. Phn than cc loi b ny c cha ti 33-42% S v 12-18% C gi l qung ln than.Pyrit ln than tuy c hm lng S ln nhng khng th t ngay sn xut axit sunfuric v hm lng Cacbon trong rt ln , khi chy: Nhit lng to ra rt ln, lm nhit kh tng cao, c th lm cho l t mau chng b ph hu; Tiu tn nhiu oxi lm gim nng SO2 v O2 trong kh l, gy kh khn cho cc giai on tip theo ca qu trnh sn xut. V vy phi nghin v ra qung ln than lm gim hm lng C trong qung xung cn 3-6% (ring l lp si c th t trc tip qung c hm lng C cao).Khi t qung ln than ngoi kh SO2 cn c mt t kh CO2, H2S, CS2, COS, Nhng khi ny khng c nh hng g ln n qu trnh sn xut. Nu dng khng kh giu Oxi t qung, c th gim c hm lng cc kh . min Bc nc ta,m than Na Dng (Lng Sn) cng cha nhiu lu hunh (c mu ti 6-8%). Vic nghin cu tch c lu hunh khi than c ngha kinh tt rt ln v tng c cht lng than, m bo an ton (trnh hin tng than t bc chy) ng thi tn dng c lng lu hunh l loi nguyn liu ta phi mua nc ngoi.2.1.1.2. Lu hunh nguyn tLu hunh nguyn t l mt trong nhng dng nguyn liu tt nht sn xut axit sunfuric v: Kihi t luu hunh ta thu c hn hp kh c hm lng SO2 v O2 cao. iu ny rt quan trng trong vic sn xut axit sunfuric theo phng php tip xc; Lu hunh cha rt t tp cht (c bit l cha cc hp cht ca Asen) v khi chy khng c x nn n gin c quy trnh sn xut i rt nhiu (bt c cc thit b c bit lm sch kh) Khi sn xut vi quy m ln v xa ngun nguyn liu th lu hunh nguyn t li l ngun nguyn liu r tin.Lu hunh c sn xut ch yu trong cc nghnh cng nghip sn xut axit sunfuric (khng 50% tng lng S), cng nghip giy xenlulo (khong 25%), nng nghip (5-15%),Mt s tnh cht ca lu hunh: nhit thng, lu hunh l cht rn mu vng. N c 2 dang th hnh: hnh thoi (khi lng ring 2,07 g/cm3) v n t (khi lng ring 1,96 g/cm3); Lu hunh dn in v nhit rt km, thc t khng tan trong nc. Tnh cht ca lu hunh lng ph thuc vo cu to phn t ca n: iu kin bnh thng phn t lu hunh gm cc vng 8 nguyn t khp kn (S8). 160oC cc mch kn m ra thnh cc mch thng lm nht ca n tng ln. Tip tc un ln lm cc mch thng b t ngn ra, lm nht gim. n 444,6oC lu hunh bt u si. Hi lu hunh gm c S8, S6, S4, S2. khong 900oC hi lu hunh ch yu l S2. Trn 1600oC hi lu hunh bt u phn hu thnh nguyn t S.2.1.1.3. Thch cao:y cng l 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 trong qu trnh sn xut axit photphoric, suppe pht pht kp, nitrophot, nitrophotka cng thi ra mt lng ln CaSO4.Thng thng, t thch cao ngi ta sn xut lin hp axit sunfuric v xi mng. Mun th t hn hp thch cao, t st v than trong l quay. Khi , CaSO4 b kh, cho SO2 em i sn xut axit sunfuric; phn x cn li thm mt s ph gia, em nghin sn xut xi mng.2.1.1.4. Cc cht thi c cha lu hunh: Kh l luyn kim muKh l trong qu trnh t cc qung kim loi mu nh qung ng, ch, thic, km, c cha nhiu SO2. y l ngun nguyn liu r tin v vic thu hi SO2 trong khi l cn tng cng bo v sc kho cng nhn, bo v mi trng.Ta c th dng cc loi l nh: l nung, l chuyn, l bc nc, l phn x, l lp siThnh phn kh l ph thuocj vo nguyn liu, cu to l v iu kin t. V vy nng khi l dao ng trong phm vi kh rng.Loi lThnh phn kh, %

SO2SO3O2

L nung7 - 100,3 0,58 10

L bc nc4 8 -9 15

L chuyn80,510

L phn x1 2,5-0,3 1,2

L lp si8 - 14 -3 - 10

Kh hydro sunfua (H2S)Khi cc ho than, khong 50% tng lng S c trong than s i theo kh cc, ch yu dng H2S (95%) . Thu hi lng H2S ny khng nhng c ngha kinh t m cn m bo iu kin v sinh mi trng.T H2S c th sn xut axit sunfuric theo phng php tip xc t hoc em sn xut lu hunh nguyn t. Khi lKhi t than trong l ca cc ni hi, lu hunh v cc hp cht c trong than s chuyn thnh SO2. y cng l ngun nguyn liu ng k sn xut axit sunfuricTt nhin mun s dng c n cn phi gii quyt vn thu hi v lm giu kh SO2 hoc thit lp s sn xut axit sunfuric trc tip t kh SO2 ngho. Axit sunfuric thiSau khi dng axit sunfuric lm tc nhn ht nc, tinh ch du m, sunfo ho cc hp cht hu cs thu c cc cht thi cha nhiu H2SO4 (20-50%)Trong cng nghip gia cng kim loi v ch to my, sau khi ra kim loi cng thu c cht thi cha 2-4% H2SO4, khong 25% FeSO4. Cht thi khi sn xut TiO2 cha 15-20% H2SO4 v 45-55% FeSO4Tm li, nguyn liu sn xut axit sunfuric rt phong ph. T l gia cc dng nguyn liu dng cng nghip sn xut axit sunfuaric khng ngng thay i theo thi gian v tu tng nc.Hin nay trn ton th gii th t l nguyn liu chnh dng sn xut axit sunfuric nh sau: lu hunh chim khong 2/3, pyrite 1/6, cn li cc dng nguyn lieuj khc.Phng hng s dng nguyn liu trong sn xut axit sunfuric hin nay l: Tn dng kh thi trong cc l luyn kim mu, H2S trong kh cc, kh thin nhin. Tn dng qung ln than, qung tuyn nooirm axit thi; Sn xut lin hp axit sunfuric v xi mng t thch cao.2.1.2. Tnh cht, c im ca SO2:Lu hunh ioxyt l kh khng mu, nng hn khng kh 2,3 ln. C mi hc kh chiu.SO2 nguyn cht (100%) p sut thng v nhit -10oC t ho lng.Khi ho tan kh SO2 trong nc to thnh axit sunfur yu v khng bn:SO2 + H2O H2SO3SO2 kh d ngng t li thnh cht lng khng mu, cht lng ny si nhit -10oC. Khi SO2 bay hi th nhit gim xung mnh (c th ti -50oC).SO2 d tan trong nc.SO2 dng iu ch axit sunfuric v cng dng iu ch rm, r, len, la v l cht kh dit nm mc trong hm ngm, kho cha, thng ln men.2.1.3. Tin hnh t Pyritt Pyrit trong dng khng kh c tin hnh trong cc thit b c cu to khc nhau di p sut kh quyn. Qu trnh t Pyrit c biu din bng phng trnh tng qut:4FeS2 + 11O2 2Fe2O3 + 8SO2 + 3400kJPhng trnh ny c dng tnh cn bng vt cht v nhit lng.Trn thc t qu trnh mt chiu ny bao gm mt dy cc phn ng ho hc xy ra song song v ni tip nhau. Giai on khch tn hn ch tc chung ca qu trnh nhit cao.Khi t chy Pyrit nhit cao trn 500oC, u tin xy ra s phn hu pyrit : 2FeS2 2FeS + S2Lu hunh chy rt nhanh trong pha kh:S2 + 2O2 2SO2Sunfua st li oxi ho theo phng trnh:4FeS2 + 7O2 2Fe2O3 + 4SO2Trn thc t, di 600oC oxi xy ra qua s to thnh sunfua st (l hp cht trung gian). Khi nhit cao hn th thot tin s to thnh FeO sau l Fe3O4 hay Fe2O3Trong mi trng hp khi oxi ho sunfua s to thnh mt mnh mng oxyt st, v vy qu trnh tip tc chy lu hunh s b hn ch bi tc khch tn ca oxi khng kh vo ht nhn FeS v bi tc khch tn ngc SO2 t chiu su ca ht Pyrit. Qu trnh ny gi l qua trnh khch tn trong v n khng ch tc chung ca qu trnh t qung pyrit. C khong 5- 10% S trong qung s b chuyn thnh kh SO3.Khi x ra khi l c nhit cao v d oxi nh th phng trnh tng qut t qung trong l tng si c biu din:3FeS2 + 8O2 Fe3O4 + 6SO2 + QKhi qu trnh t xy ra th cc sunfua kim loi khc c trong thnh phn cng s b oxi ho, cn cacbonat s b phn hu. Trong thnh kh cn c As2O3, SeO2 l tp cht ca qung v hi m ca pyrit.Oxyt st, cc mui sunfat, oxyt cc kim loi khc, thch cao, alumino-silicat v FeS khng oxi ho ht s i vo x.Trong x c cha 0,5-2% S.Nhng s liu thc nghim c trng cho mc chy S khi t qung pyrite trong lp bt ng a trn hnh?HNH Viu kin ti u nung c th xc nh khi phn tch nh hng ca cc yu t khac ln tc qu trnh theo phng trnh ca phn ng d th:

ng lc qu trnh s tng ln khi tng hm lng FeS2 trong qung pyrite v tng nng oxi trong hn hp kh vo.C th tng ng lc bng cch lm giu qung pyrit (tch tp cht khi FeS2) nh phng php tuyn ni, hoc khi t qung th dng khng kh c lm giu O2. Tuy nhin dng 2 phng php ny i hi thm nhiu chi ph nn t dng.Thng thng ly d khng kh trong khong 1,2 1,8 so vi l thuyt tnh theo phng trnh:4FeS2 + 11O2 2Fe2O3 + 8SO2 + 3400kJ3FeS2 + 8O2 Fe3O4 + 6SO2 + QC th tng tc phn ng thong qua hng s tc k. Mun vy c th tng nhit . Tuy nhin phng php tng nhanh nhit s hn ch v s lm chy cc ht pyrit trong b phn nui. Qu trnh khch tn ngoi c cng ho bng tc khuy trn pyrite trong dng khng kh. Tuy nhin qu trnh chy b hn ch bi s khch tn ca O2 v SO2 trong mao qun pyrit st (qu trnh khch tn trong xng). V vy, cho qu trnh khch tn c d dng v tng b mt tip xc F ca pyrit vi oxi khng kh phi em nghin mn qung pyrit.Thng thng qung pyrit tuyn ni c khch thc t 0,03 0,3 mmB mt tip xc ca pyrit vi khng kh cng c tng ln khi khuy trn. iu ny ph thuc vo loi thit b v c cu ca thit b.Sn phm ca qu trnh t qung l: O2, SO2, N2 v tp cht. Oxy cn c trong kh l oxy ho SO2 thnh SO3. T l O2 v SO2 trong h hp kh (khng k SO3) c tnh theo cng thc:

Trong :CO2, CSO2: nng ca O2 v SO2 trong kh tnh theo % th tch.m: t l s phn t O2 tham gia vo phn ng trn s phn t SO2 to thnh sau phn ng (tnh theo phng trnh tng qut);n: hm lng ca O2 trong khng kh tnh theo % th tch

2.1.4. Thit b t pyrite C th dng 3 loi l: L c kh L t bi L tng si Hai loi l sau c din tch tip xc b mt tip xc rt ln tc l bng tt c din tch b mt ca cc ht2.1.4.1. L c kh:y l l vn nng c th t bt k loi qung no. Dng l ny c th t qung pyrit tuyn ni, qung nguyn khai, cc loi qung sunfua kim loi mu v cc kh cha SKhi t qung pyrit thu c kh cha 9% SO2, 9% O2 v N2 chim 82%.X ra khi cha 2% S cha chy.Nng sut lm vic ca l trung bnh l 185 kg/m3.ngy m (khi tnh nng sut lm vic ca l, pyrit t nhin c tnh thnh qung kh cha 45% S. Trong qung t nhin S cha thng t hn 45%, v vy khi tnh nng sut theo qung t nhin s c gi tr ln hn).Trong khi t, qung pyrit tuyn ni d ang nng chy thnh cc, v vy trong l khng cho php nhit cao qu 850 900oC. Mt khc, nng nhit l to iu kin cho l d b g, gy cc rng l bng gang, bn trang l thm ch l van l. bi ca l c kh l 10g/m3.Loi l c kh c cu to phc tp, nng sut thp, t, lu hunh chy khng hon ton nn ngy nay t c s dng. 2.1.4.2. L t bi (l phun)L c dng tuyn qung pyrit tuyn ni v kh. Nhng ht pyrit nh ang bay v chy c bao bc bng khng kh nn chy mnh v khng b kt khi nh trong l c kh.Loi l ny nhit c th dt n 1100oC, v vy ch cn a vo l mt lng d khng kh rt nh.Kt qu thu c 13% kh SO2.Trong qung cn cha 1 -1,5% S cha chy ht.C cu thit b n gin, nng sut ca l t ti 700 - 1000 kg/m3.ngy m.Kh ra khi l c nhit 1000oC c s dng trong cc thit b tn dng nhit.Nhc im chnh lm hn ch s ng rng ri ca loi ny l: Cn phi dng qung pyrit tuyn ni v kh, hm lng S t dao ng. Khi thay i thnh phn qung th thnh phn kh ra b dao ng rt ln. Nu qung m th m s lm v vi phun v lm hng l. bi ca kh ra thng 100g/m3.2.1.4.3. L tng siDng t qung pyrit tuyn ni, qung nguyn khai v cc loi qung sunfua khc.Khc vi l c kh, l tng si khng th t nhng loi qung c kch thc ht khc nhau (trong cng 1 l) bi v vn tc khng kh tng ng vi s l lng ca cc ht v t l thun vi kch thc ca chng. V d i vi cc ht to qung nguyn khai vn tc ca kh s ln hn 10 ln so vi vn tc kh khi t cc ht qung tuyn ni.Trong cc l tng si cc ht c bao ph hon ton bng khng kh do cng lm ca l cao hn v thng t 1000 1800kg/m3.ngy m.Thnh phn kh ra cha 15% kh SO2.Trong x ra cha 0,5% S cha chy ht. tn dng nhit phn ng, cc ng ca nhng l tn dng nhit c t trong dng kh v t trc tip trong c lp si, h s truyn nhit cao hn nhiu so vi dng kh.Nhit n nh trong ton lp, bng phng php dn nhit ra, nhit trong ton lp si c gi n nh mc 800oC.Qu trnh t pyrit trong l tng si xy ra trong min khch tn. min ny tng nhit khng lm tng tc qu trnh. Thc ra nhit tng c lm tng U nhng khng ng k (ch yu do tng b mt tip xc F). Hn na nhit cao qu s lm chy tp cht v lm cho pyrit kt khi. V vy nhit qu trnh ch gi 800oc. bi ca kh trong l tng si 300g/m3Tuy nhien do nhit lm vic qu ln, nng SO2 khng kh cao, qung pyrite chy tt hn nn l tng si c dng rng ri trong cng nghip sn xut H2SO4 v trong luyn kim mu.Bng ?: so snh ba loi thit bCc ch tiuL c khL t bi L tng si

QungBt kTuyn ni Bt k

Cng lm vic, kg/m3.N185700 - 10001000 1800

Nhit lm vic, oC850 900 1100800

Hm lng SO2 ra, %91315

Hm lng S trong x, %21 1,50,5

bi, g/m310>100300

2.1.5. t chy lu hunhQu trnh xy ra d dng v n gin hn t pyrit theo phn ng:Sr + O2 SO2 + 296kJThc t lu hunh trc khi chy chy lng (tnc = 113oC), bay hi (ts = 444oC) v chy trong pha kh. Nh vy bn thn qu trnh chy l qu trnh ng th.Khi tnh ton thnh phn kh theo cng thc:

t vi qu trnh t lu hunh th n gin v m=1 t lu hunh trong khng kh (n=21):

C ngha l trn l thuyt c th nhn c kh cha 21% SO2Trong thc t sn xut thng ly d khng kh v thu c kh cha gn 12% SO2. t lu hunh nguyn cht nguyn cht ngi ta dng thit b vi phun v xiclon.

Hnh: B nu chy lu hunhHnh: Thit b vi phun t lu hunh1-v thp 5-vi phun lu hunh lng2-lp gch chu la 6-hp a khng kh vo3-lp amian 7-vi phun nhin liu4-vch ngnTrc khi cho vo thit b ngi ta nng chy lu hunh bng hi trong l nu, em lc sch khi tp cht v dng kh nn phun qua vi phun vo thit b t. Khi lu hunh s bay hi v bc chy.Trong thit b vi phun s khuy trn lu hunh v khng kh cha , qu trnh b lm chm v s khch tn v tin hnh t do.Trong thit b xyclo nh a khng kh vo di 1 gc tan no nn s khuy trn xy ra mnh lit gia lu hunh v khng kh, v vy qu trnh chy rt mnh.Bi th nn thit b xyclon ngy cng chim u th so vi thit b phun kiu c.2.1.6. Lm sch kh SO2:Kh ra khi l nung c nhiu bi v vy cn lm sch sn phm axit khng b nhim bn (bi lm bn thit b, tc ng ng, gim hot xc tc).Kh ra khi thit b t qung cha 300g/m3 bi.Thnh phn tp cht cha As, Se v Fe thay i tu theo nguyn liu v ch t, trung bnh trong khong:As = 50mg/m3Se = 25mg/m3Fe = 15mg/m3Quy trnh lm sch bi xem trong s nguyn tc sn xut axit H2SO4.2.2 . Oxi ho SO2 thnh SO3:2.2.1. L thuyt chung:Oxy ho tip xc SO2 l v d c trng cho qu trnh d th, to nhit v xc tc.Cn bng ca qu trnh thun nghch ny l:2SO2 + O2 2SO3 + 296,7kJ (500oC)Tng ng vi quy tc Le-Shatelia cn bng s dch chuyn v pha thu SO3 khi gim nhit v tng p sut, tng ng s tng mc chuyn ho cn bng SO2 thnh SO3.

y:G*_lng SO3 thu c trng thi cn bng.Gmax_lng SO3 ln nht c th thu c khi chuyn ho hon thnh SO2 thnh SO3 theo phn ng:P*SO2, P*SO3: p sut ring phn cn bng ca SO2 v SO3 hay l nng cn bng (C*).Khi tng p sut th tc phn ng tngCn bng lng c th tnh theo hng s K bng cn bc hai ca hng s cn bng:

Hoc c th tnh theo nng u SO2 v O2:

2.3. Hp th SO3 thnh axit H2SO4