so sánh Ưu Điểm kinh tế các quá trình trích ly h3po4 và tận dụng photphogip

7/24/2019 So Snh u im Kinh T Cc Qu Trnh Trch Ly h3po4 V Tn Dng Photphogip

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SO SNH U IM KINH TCC QU TRNH TRCH LY H3PO4 V TNDNG PHOTPHOGIP

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Phn 1

SO SNH U IM KINH TCC QU TRNH TRCH LY H3PO4

(DH; HH; HDH)

I. MU

La chn quy trnh ti u cho mt dn sn xut axit photphoric theo phng phpha tan qung photphat bng axit sunfuric (phng php trch ly) l mt cng vicquan trng. C nhiu yu tnh hng n sla chn ny trong chyu l ngun

qung u vo. Bn cnh , cc yu tkinh tlin quan khc nh gi lu hunh, chiph in, nc, hi nc... v c shtng a phng cng c tc ng khng nh.Nhng yu tny c thvn cn thay i kcsau khi nh my i vo hot ng.

Trong phn ny chng ti xin gii thiu mt squy trnh c bn c p dng trongsn xut axit photphoric trch ly vi nhng yu tso snh vcc mt cng nghvkinh t.

Cc quy trnh sn xut axit photphoric theo phng php trch ly c thc chia lm5 dng c bn da trn cc c im ha l (iu kin ha tan v ti kt tinh, sln

lc ...( tng ng vi tn phphm photphogip nh sau:(1)Quy trnh ihyrat (DH) nng sn phm 27 - 30% P2O5(2)Quy trnh ti kt tinh hemihyrat (HRC), nng sn phm 27 - 3 1% P2O5(3)Quy trnh i/hemihyrat (DHH), nng sn phm 32 - 37% P2O5(4)Quy trnh hemihyrat (HH), nng sn phm 40 - 48% P2O5(5)Quy trnh hemi/dihyrat (HDH), nng sn phm 40 - 50 P2O5

II. CC QUY TRNH C P DNG

1 . QUY TRNH IHYRAT (DH)

C hai loi quy trnh DH l quy trnh DH-is v DH-sg:

a) Quy trnh DH-is: Mc ch ca quy trnh DH-is (iso-sunfat) l t c mitrng phn ng ng nht hon ton bng cch sdng cc bnv tng cng titun hon. Nu qung photphat rt mn hoc dbha tan th quy trnh ny c thsrt c hiu qudo lc tt. Nhng do chsdng mt bha tan nn chu trnh ha tanphotphat tng i ngn, cc tinh thphotphogip (PG) cha kt tinh xong c


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chuyn n phn lc. Mc ch t sng nht ha hon ton ny cng lm hn chdung lng ti a ca tng m.

Vn tn ti chnh ca quy trnh ny l vic kh t c sng nht ha gncc im np liu.

b) Quy trnh graien sunfat (DH - Sg)

Quy trnh DH - sg i hi phi c hai bhoc hai khoang bvi lu lng tun hongii hn gia chng. iu ny c thto iu kin cho qung photphat c bsungvo im c nng sunfat khc so vi phn cn li ca hthng phn ng hoc voim cch im bsung H2SO4 mt khong cch nht nh. Tltun hon v tc

phn ng ca qung photphat sl yu txc nh bc gradien sunfat.

So snh:

Hiu qu tng i ca hai quy trnh DH-is v DH-sg ph thuc vo tnh cht ca

qung photphat v gi trmc thch ng ca quy trnh DH-sg. Trong tng trnghp c th, 2 quy trnh c th ging nhau hoc khc nhau rt nhiu. Trong nhiutrng hp, cc thay i v tnh cht ca qung photphat c th gy nh hng lnhn so vi skhc bit gia hai quy trnh, trong khi mt s trng hp khc, skhc bit gia 2 quy trnh li tra quan trng hn.

c) Quy trnh DH hai giai on

Ngi ta c thha tan qung photphat theo nguyn tc quy trnh DH thnh 2 giaion. Trong tng iu kin cth, vic p dng ny c thsthun li hn. Hai qutrnh ha tan hai khu phn ng nht nh m khng cn ti quay vng gia hai giaion. Theo quy trnh ny c 2 kiu: kiu 1 l ca Rhone - Poulenc Diplo v kiu 2 lca Double Dihydrate Prayon Process ca hng Prayon (B). Quy trnh Diplo c mtgiai on v Prayon c hai giai on lc.

2. QUY TRNH TI KT TINH HEMLHYDRAT (HRC)

Trc y, nht l Nht Bn, quy trnh ny c p dng kh phbin. Nht Bn xy dng nhiu nh my nhhot ng theo quy trnh HRC sn xut photphogiplm phgia xi mng. Nhng quy trnh NISSAN HRC duy nht c p dng thnhcng quy m thgii.

Quy trnh ny i hi phi nghin mn qung photphat to cc iu kin phn ngc thkim sot c trong cng on hemihydrat. Chi ph nghin c b p biPG c sn xut ra c gi trcao. Thng thng, quy trnh ny cho php sn xutaxit photphoric nng 28 - 30% P2O5 v 3% SO4.


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Mt snh my ca Nht Bn chy theo cng nghny ang dkin c ci to livn hnh theo quy trnh HDH, v quy trnh ny cho php loi bcng on nghinmn, ng thi sn xut axit photphoric c hn m vn m bn cht lng PG.

3. QUY TRNH I/ HEMLHYRAT (DHH)

Cng ty Nht Bn Central - Glass v Cng ty BPrayon cng nhau pht trin quytrnh DHH c gi l quy trnh CENTRAL - PRAYON. Quy trnh CENTRAL -PRAYON c p dng sn xut trc tip ihyrat cp thng phm, nhccc tnh "tkh" ca b hemihyrat.

Mc tiu quy trnh hai bc ny l tch cng on sn xut axit khi cng on snxut canxi sunfat, to iu kin sn xut axiit c hn v PG tinh khit hn.

giai on u ca quy trnh CENTRAL - PRAYON , ngi ta chcn loi bmtphn axit photphoric ra khi hn hp bn bng cch lc hoc ly tm. B PG khngra c bn ha trc khi a vo btch nc. Sn phm axit c tht nng

37% P2O5, ty theo cht lng qung photphat sdng. Sn phm axit ny lun chm lng sunfat thp, ng thi hiu qucao ca quy trnh sm bo mc tiu haoH2SO4 thp.

Trong btch nc, axit H2SO4 c bsung vo slm tng nhit v nng sunfat, lm tng tc chuyn ha ihyrat thnh hemihyrat. Ngi ta cng chothm mt lng nhhi nc khng chnhit .

Schuyn ha tihyrat thnh hemihyrat din ra tng i ddng. Quy trnh nyto ra b hemihyrat tinh khit dlc nhnng dsunfat cao, hm lng P2O5 thp.

Do tc chuyn ha nhanh nn to ra hemihyrat tng i km bn, do ngi ta phi sa i thit k li b lc. Cc thit bmi nht ca Bird - Prayon (b lcnghing) v Prayon - EIMCO (h thng lc bng chuyn) c sn xut png quy trnh hemihyrat, vn hnh cho 11 nh my sut 20 nm qua.

4. QUY TRNH HEMLHYRAT (HH)

Trong nhiu nm qua, ngi ta cgng sn xut axit photphoric c (n nng 48% P2O5) trc tip tngay sau blc. Ci gi phi trcho yu cu ny l hiu sutthu hi thp. Tuy nhin, trong mt strng hp u im ca cch lm trn vn ln

hn so vi nhc im ca n nht l khi c ngun qung photphat v axit sunfuric rv khi cc iu kin cung ng hi, in v nc bhn ch.

Ti Lin X c, axit photphoric c sn xut theo quy trnh hemihyrat t qungphotphat Kola chim thphn ln nht. Nhng ti cc nc khc, quy trnh nykhng c p dng phbin nh vy.

Hin nay, cng, nghHH ang c vn hnh quy m cng nghip l cc quy trnhNORSK - HYDRO HH, OXY HH v PRAYON HH.


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5. QUY TRNH HEMI- IHYRAT (HDH)

Quy trnh hemihyrat/ ihyrat (hai cng on) l quy trnh sn xut axit c (n50% P2O5) v PG tinh khit cao, vi mc tiu hao H2SO4 thp . Tuy nhin chi phu t cho quy trnh ny kh cao.

Nhc im chnh ca quy trnh l phi vn hnh 2 b lc, iu ny lm gim khnng vn hnh lin tc v vi lc ca blc u tin (HH) phi c ra bng nclc tb lc thhai cn bng lng nc. y ang l ch cho s thay icng nghnhm trnh hin tng trn. Ngoi ra cng nghcn c mt snhc imkhc na.

Mt squy trnh HDH hin ang c p dng l quy trnh ca cc cng ty NorskHydro , Nissan v Prayon PH2 & PH3.

III. U IM V NHC IM CA CC QUY TRNH

Khi nh gi cc quy trnh sn xut axit photphoric theo phng php trch ly, cn xtn nhng kha cnh sau:

- Nguyn liu qung photphat c thch hp khng.- Hiu quthu hi PG.- Cc tht thot khc (tht thot khi np qung photphat, tht thot do chy trn,

tht thot trong qu trnh khi ng, ngng dy chuyn,....).- nh mc tiu hao qung photphat.- nh mc tiu hao axit sunfuric.- Khnng sdng axit sunfuric nng thp hn.

-

Nhu cu nghin qung photphat.- Khnng sdng qung photphat kh, m hoc dng bn.- nh mc tiu hao nc.- nh mc tiu hao in.- nh mc tiu hao hi nc/ Nng cn thit ca axit sdng.- Yu cu vvt liu hp kim cao cp dnh cho thit b.- Thi gian vn hnh thc ttrong nm.- Khnng thao tc dy chuyn c ddng khng.- Hm lng cht rn trong sn phm axit photphoric.- Cht lng sn phm axit photphoric.-

Cht lng PG.

1 . Quy trnh DH

Quy trnh DH c thc coi nh quy trnh c bn (lm chun) nh gi xp loi.Cc quy trnh khc c thc nh gi so snh tng i vi quy trnh DH.


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Quy trnh DH l quy trnh c vn hnh tlu vi nhiu loi qung photphat khcnhau, nh ngi ta c nhiu kinh nghim vquy trnh ny. Hiu sut thu hi PGt 94,5 - 97%. Hiu sut thu hi chung ca quy trnh t 93,5 - 96,5% (tnh theolng tiu hao qung photphat so vi lng qung photphat c nhp vo nh my).Tht thot do chy trn, khi ng v ngng sn xut, cc chu kra, thi gian lmsch b... lm gim 0,5-1% hiu quchung. Ngoi ra cn tht thot qung photphat do

qu trnh bc d, vn chuyn, nghin kh... Nhng nu trc tip tnh theo photphatmn ththng nghin t hoc sdng bn photphat np vo quy trnh th tht thotqung gn nh bng khng.

Quy trnh DH c thchp nhn axit sunfuric long lm nguyn liu. Trc y, ngita cn dng dung dch amoni sunfat thi lm nguyn liu. Mc tiu hao H2SO4

ph thuc vo kt qu phn tch qung photphat (ch yu l t l CaO/P2O5 trongqung) v vo hiu sut ca quy trnh. Kch thc chun ca ht qung dng trongquy trnh DH phi m bo sao cho khng n 40% s ht nm li trn sng 100mesh, nhng cht c ththay i nhiu ty theo tnh cht ca qung.

Nu cn nghin qung, c thsdng quy trnh nghin t gim tiu hao in vtht thot khc. Nguyn liu photphat vi cht theo yu cu c thc np dngkh, m hoc dng bn m khng lm gim hiu sut thu hi. Mc tiu hao nc schl vn cn cn nhc nhiu mt v khi hthng nc c u t tt, c thgim tithiu nh mc tiu hao nc sch.

Nc lm lnh l nc tn dng tao, h, sng, bin, thng c sdng quayvng nn chi ph cho n khng ang k(ngoi chi ph bm) so vi cc chi ph khc.

Tiu thin thng c coi l yu t rt quan trng trong chi ph vn hnh. Tuynhin, thng thng mc tiu hao in cc quy trnh sn xut axit photphoric khngkhc nhau nhiu.

Trn thc t, tiu hao in ln nht c dnh cho cng on nghin v cho qut cahthng lm lnh khng kh. Tiu hao in cho khuy, lc, bay hi . . . tng i thpMc tiu hao hi nc thng c coi l mt trong nhng yu tchnh nh hngn hiu qukinh tchung ca nh my. Trong yu cu sdng axit photphoric (snxut MAP, DAP, supephotphat kp, NPK...) th nng axit photphoric gi vai trquyt nh v nng axit li lin quan n mc tiu hao hi nc.

Tt nhin, nu yu cu i vi axit photphoric l trn 30% P2O5 th nh my sn xutaxit photphoric theo quy trnh DH phi c cng on c c. Nu nh my sn xutaxit sunfuric nm bn cnh li c ngun hi nc s dng cho cc mc ch khchoc cho sn xut in th c thkt hp un c axit photphonc n 42% P2O5.

Nu nh my khng c ngun cung cp hi nc di dng sn phm phca phnxng sn xut axit sunfuric hoc ca nh my khc, m cng khng c ngun


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nc nng hi lu tcc cng on khc th bt buc phi sdng ni hi snxut hi. Chi ph sn xut hi nh vy phthuc vo gi nhin liu a phng.

Quy trnh DH l quy trnh thc st gy n mn nht. cc quy trnh khc, nh HHv HDH, do nhit cao hn nn vn n mn thit br rt hn.

Quy trnh DH l quy trnh dvn hnh nu chsdng chn lc mt sloi qungphotphat. Nu thay i ngun cung cp qung th cn c mt thi gian thch nghi ngi vn hnh iu chnh sang chvn hnh ti u.

Cht lng sn phm axit photphoric ca quy trnh DH tng i cao, c th lmchun cho cc quy trnh khc.

Cht lng PG phthuc nhiu vo ngun qung photphat. Tuy nhin d lng P2O5thng kh cao nn vic xl thnh PG hng thng phm skh tn km.

2. Quy trnh HRC

Quy trnh ny c sdng Nht Bn (ni khng c ngun thch cao tnhin vitrlng ng k) sn xut phgia ng rn xi mng. PG ny c sn xut trctip tb lc, chqua cng on sy, nh gim nhiu chi ph tinh ch.

So vi quy trnh DH c bn, chmt s loi qung photphat nht nh mi c thc xl bng quy trnh HRC. Sc mt ca cc tp cht nh stronti trong qungphotphat thng gy kh khn cho schuyn ha HH thnh DH.

Hiu quthu hi PG quy trnh ny thng cao hn so vi quy trnh DH tiu chun.

Hm lng sunfat ca sn phm axit (ni chnh xc l t lSO3/P2O5), thng caohn so vi quy trnh DH, mc tiu hao H2SO4 ln hn, nhng hiu sut thu hi axitphotphoric cng cao hn. Axit sunfuric thng c np vo trc tip dng long(khong 60%) khng chnhit ca cng on HH.

Qung photphat cho quy tnnh HRC cn c nghin mn hn so vi quy trnh DH:y l mt cng on c chi ph rt cao, v vy nn nhiu nh my p dng quy trnhNISSAN H ang xemxt chuyn sang quy trnh HDH.

Qung photphat c thc np vo dng kh hoc m, nhng khng c dngbn (v yu cu nhit ca cng on HH), do khng tn dng c u im ca

cng on nghin t.

Do yu cu nghin mn hn v do c nhiu bha tan v ti kt tinh cn khuy nntiu hao in quy trnh HRC cng cao hn so vi quy trnh DH.

Cng on HH ca quy trnh HRC c tnh n mn c bit mnh do lm vic nhitcao, v vy, ngi ta thng sdng cch khuy bc cao su hoc thp khng g.


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Thi gian vn hnh thc ttrong nm ca nh my p dng quy trnh HRC tng tnh nh my p dng quy trnh DH. Nhng do mc khuy thp hn trong cc btikt tinh nn cc bny phi c ra sch thng xuyn hn so vi bha tan caquy trnh DH, khin thi gian lm vic gim i mt t (310 - 320 ngy/ nm).

Quy trnh HRC l quy trnh tng i dvn hnh vi iu kin n nh thnh phn

qung photphat.

Hm lng cht rn trong sn phm axit photphoric ca quy trnh HRC thp hn sovi mc trung bnh ca quy trnh DH. Cht lng axit thnh phm km hn so viquy trnh DH do PG khng hp thmt scht hu c. Hm lng cht hu c trongaxit cao hn, nhng cht lng PG li tt hn. Mc ch ca quy trnh HRC l tinhnh xl PG ngay trong nh my axit photphoric m khng phi xl bsung saukhi phphm ra khi nh my. PG c sn xut theo quy trnh ny t cc ngunqung photphat thng thng sc sdng trc tip lm phgia ng rn xi mngm khng cn xl tip bng ha cht (chcn sy kh). Nhng nu sdng cho cc

mc ch khc nh lm va PG, tm lati trt va th i vi a s cc loi qungphotphat cn phi c cng on ra t trc khi sy kh.

3. Quy trnh DHH.

Nh nu trn, 2 cng ty Nht Bn v B cng pht trin quy trnh DHH c gil quy trnh CENTRAL - PRAYON. Pha Nht Bn mun sn xut cht thay ththchcao tnhin cht lng cao, cn pha Bmun gii quyt vn dtiu hy phthi dodin tch t phthi ngy cng eo hp.

Quy trnh DHH c vn hnh i vi nhiu loi qung photphat. Cng ty ny s

dng mt phgia v c sn xut axit photphoric 37% P2O5 ng thi vn duy trskt tinh theo hnh thc DH. Yu tquyt nh sdng phgia da trn kt qu

phn tch qung photphat v yu cu vnng ca sn phm axit, c xt n chi phphgia. Ngi ta cng sdng qung photphat hn hp tng nng axit thnhphm m khng cn sdng phgia.

Quy trnh DHH l quy trnh kt tinh kp hon ton, c thtch sn phm axit sau tha tan u tin, thc hin ti kt tinh, PG c tinh khit cao, tht thot photphatthp v hiu sut qu trnh cao (98 - 98,5%). Hm lng P2O5 trong bn np giaion hai vo b lc HH cui cng nm trong khong 23 - 26%. Tht thot do khing v ngng vn hnh c gim nhiu. Hiu sut thu hi chung cao (mc 98%)c ngha l nh mc tiu hao photphat thuc vo loi thp nht trong cc quy trnhsn xut axit photphoric trch ly.

Sn phm axit photphoric to ra giai on u (DH) c hm lng sunfat rt thp, vvy lm gim nng axit sunfuric trong dng cht ny. Cng vi hiu sut thuhi chung cao, yu ttrn lm cho quy trnh DHH l mt trong nhng quy trnh tiu


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hao t axit sunfuric nht. Tuy nhin c mt im hn chl do cn scn bng nccht chnn ngi ta phi sdng axit sunfuric c (> 70% H2SO4).

Do iu kin ha tan tt v hm lng sunfat phn DH thp nn c thdng nhiuloi qung photphat khc nhau vi cht di 0,5mm.

Hm lng nc trong PG tquy trnh ny thuc vo loi thp nht trong cc quytrnh sn xut H3PO4 trch ly. Hemihyrat y c hm lng nc tdo rt thp vmt phn themihyrat chcha na phn tnc.

Tiu thin cho thit bkhuy quy trnh DHH c mc tng ng vi quy trnhDH. Do iu kin ha tan thun li nn phn ha tan quy trnh DHH c thcgim bt vthtch. Cng on tch nc nhanh nn i hi thtch tng ng nhhn nhiu so vi cng on chuyn ha tHH sang DH. iu ny c ngha l nu sdng qung photphat nghin th hn m quy trnh c thchp nhn th mc tiu thin chung ca cquy trnh thp hn nhiu so vi quy trnh DH.

Nng axit thnh phm (37% P2O5) c thc iu chnh nhm gim ti a lnghi tiu th.

Chnhng hp kim c bit hoc thp bc cao su mi c thdng lm cnh khuycho b ti kt tinh. Thit bphn ng thng c b tr sao cho dung dch c thchy qua ltrn vo thit blc m khng cn bm ly tm.

Quy trnh DHH l quy trnh dvn hnh khi xc nh c cc thng sti u cacng on ti kt tinh i vi loi qung photphat cth.

Hm lng cht rn trong sn phm axit thay i ty theo thit btch nc ci giaion trung gian. Nu sdng bm ly tm, hm lng cht rn c thln n 3%, nusdng blc c thgim hm lng ny xung 0,5%.

Sn phm axit photphoric c nng sunfat thp v hm lng cht hu c thp,trong khi PG l sn phm dng hemihyrat vi hm lng P2O5 v florua thp, cthc ti hyrat ha trc tip bng cch cho hp thnc tdo. Phng php ny c sdng sn xut cc ht PG "kh" ngay tsau khi lc nhiu nh mysn xut axit photphoric ca Nht Bn. Cc ht PG c sdng lm phgia ximng. Hemihyrat c hirat ha li nh vy c hm lng tp cht rt thp v c

thsdng trc tip lm va PG.4. Quy trnh HH

u im chnh ca quy trnh HH l cc chstiu hao (hi, in, nc) thp. Nhngquy trnh ny khng t hiu sut sn phm cao nn chc thp dng mt cch hnch.


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Khi p dng quy trnh cho cc loi qung photphat khc nhau, vn ln duy nht cngii quyt l s khc bit r rt ca hin tng ng cn trn mng lc HH. Hintng ng cn ny thng khng phi l kt quca shyrat ha HH (c thgiiquyt bng cch thay i thit b), m l do skt ta flosilicat trong h thng ra

bng nc lc. Ngi ta c thgii quyt mt phn vn ny bng cch phun hinc. Mt s loi qung photphat li khng gy ra vn ny, nhng mt s loi

qung khc thng c xu hng gy ra vn ny m chc thgii quyt bng cchthay i thit kthit bv phi trn photphat mt cch thch hp.

Hiu sut thu hi PG ca quy trnh HH thp nht trong s cc quy trnh sn xutH3PO4 trch ly. Ngoi ra cn nhng vn nghim trng l s tht thot kh tnhton c trong qu trnh khi ng hoc ngng thit blc, v sc schy trn axitc nu khng c hthng thu gom v.v....

Qung photphat np dng kh cng gy tht thot. Hiu sut thu hi PG nm trongkhong 90 - 94%, trong khi hiu sut chung ca quy trnh l 88 - 93%. Vi hiu sut

ny mc tiu hao qung photphat tng i cao, nhng iu c th chp nhn cnu thc hin quy trnh ny ngay ti cc mvi gi qung thp, hoc nhng ni cngun in, hi, nc gi r.

Hm lng sunfat ca axil sn phm v t lSO3/P2O5 thp hn so vi quy trnhDH. Sn phm thng cha 1,5% SO3 v t nng 40 - 48% P2O5. Tuy nhin, dohiu sut chung thp, nn nh mc tiu hao axit sunfuric cao hn so vi tnh ton.

Nu yu cu sn phm axit c hn th ngi ta phi sdng H2SO4 c.

100% qung photphat np vo c thc cht < 1mm, nhng nu sdng ht cnh

hn th cng tt. Cn bng nc ca quy trnh rt st sao, nn nu cn sn xut H3PO4c th qung photphat phi c np vo dng kh. Nu sn xut axit 40%, c thnp qung photphat vi m n 12%, nhng trong bt c trng hp no cngkhng c sdng qung photphat ly trc tip tmy nghin t.

Tiu thnc quy trnh HH thp hn so vi quy trnh DHH do PG thu c dngHH, nhng m tdo ca PG li cao hn so vi quy trnh DHH do tnh cht tinh thkhc nhau. .

Tiu thin quy trnh HH thp hn so vi quy trnh DH. C thkhng cn tiu thhi nu yu cu c ca sn phm axit l di 48%. y c th l yu tquantrng i vi nhng c ssdng nhin liu ha thch sn xut hi, nhng nu cngun cung cp hi tbphn sn xut H2SO4 trong nh my th li khng tn dngc ngun nng lng ny.

Mt squy trnh HH c vn hnh nhit cao nn tc n mn bm lc vcnh khuy cng cao hn. Nhng c thp dng phng php khuy bng dng chytc cao hn chsn mn.


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Tiu thin quy trnh HDH khng thp nh quy trnh HH, v cng on ti kttinh vi thtch tng i ln i hi phi khuy nhiu.

giai on thhai ca quy trnh l lc, lu lng nc ra ln hn do phn tDHngm nhiu nc hn, to iu kin sn xut axit H3PO4 c hn. Vn hiu qukinh tsl yu tquyt nh c nn trang bthit bbay hi cho nh my sn xut

H3PO4 theo quy trnh HDH hay khng.

Yu cu vhp kim cao cp cho thit bca quy trnh HDH cng tng tnh phnHH ca quy trnh HDH, nhng v phn DH khng c tnh n mn cao nh vy, nnc thkhng cn sdng hp kim cao cp.

Thi gian vn hnh lin tc trong nm ca nh my p dng quy trnh HDH ngn hnso vi nh my p dng cc quy trnh sn xut H3PO4 khc.

Cht lng axit photphoric thnh phm ca quy trnh HDH tng ng vi quy trnhHH, nhng axit thnh phm ca quy trnh HDH thng c hm lng flo v nhm

thp hn do cc nguyn t ny c gii phng trc phn ti kt tinh. Chtlng PG ca quy trnh HDH cao hn so vi quy trnh DH v tng ng so vi quytrnh DHH. Nhng b canxi sunfat dng HH ca quy trnh DHH c thtkh v hpthnc lin kt, cn quy trnh HDH th PG phi c sy kh nn tiu tn nhinliu.

IV. CC YU TLA CHN QUY TRNH

Khi la chn quy trnh thch hp cho sn xut H3PO4 trch ly, cn xem xt cc yu tsau vn dng hp l vo tnh hnh thc t:

1. Tnh linh hot i vi yu cu vqung photphat

Cc nh my khng nm gn mqung photphat thng cn p dng cc quy trnhsn xut cho php sdng qung photphat tnhiu ngun khc nhau, cn nh mynm ngay ti a im c mqung photphat th li cn quy trnh c thp dng choloi qung photphat cthca mny

2. nh mc tiu hao qung photphat

Khi xt nh mc tiu hao qung photphat, cn xt n gi qung photphat c cung

cp cho nh my, kccc chi ph xl ti a phng.3. nh mc tiu hao axit H2SO4

Gi axit H2SO4 c th thay i rt rng tu theo trng hp. Nu c ngun axitH2SO4 l sn phm phca nh my luyn kim hoc ca cc nh my ha cht khc,th gi H2SO4 rt thp. Nhng nu H2SO4 c sn xut tlu hunh nhp khu thgi thnh li rt cao. y l iu cn phi tnh ton.


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4. Nguy c vcc tht thot kh lg (v ddo chy trn, do np qung photphatkh,..).

Nu gi qung photphat v gi thnh axit H2SO4 cao th cc tht thot ny c thrtquan trng v cn tnh ton k.

5. Yu cu vnng ti thiu ca axit H2SO4

Vn ny c thc chai mt tch cc v tiu cc. Mt quy trnh i hi phi phalong H2SO4 c c th sgy nhiu kh khn do vn lm ngui khi pha longaxit, cn quy trnh cho php sdng H2SO4 c sc u thkhi ngun axit cung cpl axit c. Nu phi cung cp axit sunfuric long th mt s quy trnh sn xutH3PO4 skh c p dng v cc kh khn vvn cn bng nc.

6. Yu cu vnghin qung

Cn c sphi hp ng bgia vic mua sm v vn hnh thit bvi vic cung ng

nng lng p ng qung nghin t tiu chun yu cu. Nghin t c hiu qukinh thn nghin kh, nn i vi cc quy trnh sn xut H3PO4 khng cho php sdng qung photphat dng bn th ngi ta sphi sy qung nghin t hoc tinhnh nghin kh vi chi ph cao hn. Mt squy trnh cho php iu chnh cc thngsc thsdng qung photphat cht th hn.

7. m cho php ca qung photphat

Vn ny c thl quan trng i vi mt squy trnh, nhng ngc li hon tonkhng c ngha i vi cc quy trnh cho php sdng qung photphat dng bn.

8. nh mc tiu hao nc

y c th l vn quan trng nht nhng khu vc m ngun nc bhn ch,nht l khi p dng cc quy trnh to ra ihyrat (DH).

9. nh mc tiu hao in

Tiu hao in ln nht l cho cng on nghin, cn tiu hao in cho phn ng vlc (thit bkhuy, qut...) khng ng k.

10. nh mc tiu hao hi

Nu nh my sn xut H3PO4 nm gn nh my sn xut H2SO4 th c thsdnghi cao p, hi thp p v nc nng ca nh my sn xut H2SO4 cho nh my snxut H3PO4. Nhng nu nh my sn xut H3PO4 khng nm gn nh my sn xutH2SO4 th n cn c bphn to hi nc, khi nh mc tiu hao hi sl yu tquan trng la chn quy trnh sn xut H3PO4.


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11. Nhu cu vhp kim cao cp cho thit b

y l yu tkhng chb tc ng bi vn gi hp kim, m cn bi khnngcung ng nhng vt liu ny, nht l nhng nc cha sn xut c nhiu loi hpkim cao cp.

12. Yu ttng thi gian vn hnh thc ttrong nm

Nu xc nh c chnh xc tng thi gian vn hnh thc t trng nm ca dychuyn sn xut H3PO4 cng nh ca cc dy chuyn sn xut khc trong nh myth c thm bo svn hnh tri chy ca nh my, khng xy ra vn tcngn cc bkiu nt cchai. Quy m thit bchi ph u t chi ph vn hnh v chi

ph cnh khi ngng hot ng u bnh hng bi yu tny.

13. Yu cu vtrnh ca cng nhn

Nu a phng khng thcung cp cng nhn trnh th yu cu vtrnh

ca cng nhn c thtrthnh mt trong nhng yu tquan trng nht nh hng nthnh cng ca dn. c bit l i vi nhng quy trnh m cng nhn phi thchin cc thao tc chnh xc (khi ng tt thit bv tho dung dch ngn nga shydrat ha v.v...). Nu cng nhn khng trnh v knng cn thit th nguy cxy ra scsrt ln, dn n khnng phi ngng ton bdy chuyn vi hu quln.

14. Nhu cu lc

Cc quy trnh c cng on xl qung ha tan mc qu bo ha trc khi lc uc hm lng cht rn thp hn so vi cc quy trnh khc. Cc quy trnh sn xut axit

photphoric 36 - 42% P2O5 (trc khi c) thng c hm lng kt ta cui rt thp.Nu ton bsn phm axit ca nh my u c bn ra ngoi m nh my khng cbphn sn xut phn bn tn dng b lc, lng cht rn cn phi lc s tr thnhvn c nh hng ln.

15. Cht lng axit photphoric .

Tm quan trng ca yu tny phthuc chyu vo nhu cu thtrng v lnh vcsdng i vi sn phm axit photphoric.

16. Cht lng PG

Vic nng cao cht lng PG t cp thng phm c thgp phn quan trng vohiu qukinh tca nh my sn xut H3PO4. Tuy nhin, chc mt squy trnh snxut H3PO4 p ng c yu cu vcht lng PG.


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17. Chi ph u t

Thng thng, y l yu tquan trng chyu trong vic la chn quy trnh sn xutH3PO4. Nu nh my sn xut H3PO4 nm trong mt thp bao gm nhiu nh mykhc (nh nh my tuyn qung, nh my sn xut H2SO4, nh my sn xut phnha hc,...) th vn quan trng l la chn quy trnh sn xut H3PO4 ph hp nht

t hiu qucao cho ton bthp, lc ny vn chi ph u t ca ring nhmy H3PO4 khng cn l yu tquan trng nht.

Phn 2

MT SVN XL V TN DNG PHOTPHOGIP (PG)

I. KHI NIM CHUNG V CC LOI GIP V QUAN IM TN DNG

GIP NHN TO

Gip ni chung ang c tiu thtrn ton cu di bn dng chnh nh sau:

1/ Gip th tnhin di dng qung:Trlng ton cu c nh gi vo khong2.260 triu tn. Thnh phn ha hc gip tinh khit l canxi sunfat ngm 2 phn tnc (CaSO4.2H2O). Gip tnhin hin ang c sdng rng ri sn xut ximng, thy tinh, lm cht ci to t, cht n thc n gia sc, cht nhi thc phm ccanxi, chbin nm men v bia, cht n trong cng nghip ha dc, sn xut caosu, gnhn to, cht do, giy, men mu, cc sn phm git ra v.v...

2/ Gip nung:Gip tnhin thng sdng di mt sdng gip nung l:

- a - hemihyrat.- b - hemihyrat.- Cc dng anhyrit.

Hn 90% tng sgip c sdng trong cng nghip u l dng nung .

Gip nung c tiu thrng ri trong ngnh xy dng, ng ng trong cng nghipv gia dng; chng hn c sdng trong cng nghip vt liu xy dng nh chto

vch ngn, ph iu,va trt, vt liu lp, v.v... M75% gip nung c sdnglm nguyn liu sn xut lati, va trt.

Gip nung cn c thc sdng sn xut khun gm vsinh, khun kim loi,ph iu trang tr, cht kt gn trong ging khoan v.v...

3/ Gip nhn to:y l nhm c xc nh l sn phm phca ngnh cng nghipha cht. Thnh phn chyu ca gip nhn to l CaSO4 . 2H2O. Gip nhn to c th


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c ngun gc tmt scng ngh sau: Sn xut axit photphoric theo phng phpt, sn xut axit nohyaric, axit xitric, loi lu hunh tkh thi ng khi, tch trongha cht thi tnh my sn xut TiO2 bng quy trnh sunfat, v.v...

Gip nhn to c sdng chyu lm cc loi tm p, lm cht ci to t ci tong x, v.v... Nhng tn dng c chng, trc ht ngi ta phi lm sch ri

mi a vo sdng hoc xl tip (nung, v.v...).

4/ Anhyrit: Ni chung gip cng thng tn ti c di dng lin kt anhyrit(CaSO4 khan). Anhyrit cng c ngun gc tnhin, n tr vi nhit, rn cao vthm nc cng cao. Do tr m cc dng anhyrit chc ng dng hn ch.Chyu chng c dng lm vt liu xy dng, lm cht ci to t, lm cht mangcho mt sloi thuc trsinh vt hi,v.v...

Tlu ngi ta quan tm ti vic tn dng gip nhn to ni chung v PG ni ringlm ngun gip thay thcho gip tnhin, nht l cc nc khng c mgip, phi

nhp khu. Cho ti nay, vn ny dc kt lun r rng :- Gip nhn to (trong c PG) c thsdng hon ton thay thgip tnhin.- Vic xl tp cht phng xtgip nhn to khng phi l vn qu kh.- PG c lm sch chnh l ngun nguyn liu phc v cho rt nhiu ngnh.

Tuy nhin t c hiu qukinh tv ph hp tng khu vc, nh sn xutphi tip tc gii cc bi ton lin quan ti nhiu vn .

Trn thgii xu hng tn dng gip nhn to ang ngy cng tng, nht l khi tc khai thc gip tnhin mt svng ngy cng chm, trong khi lut mi trng ngycng khp cht.

II. MT SVN VXL V SDNG PG

1. Cc ngun PG v tnh hnh sdng PG

PG l sn phm phca qu trnh sn xut axit photphoric theo phng php trch lytaxit sunfuric v qung photphat. Thc tth c mt lng nhPG i tcc ngunkhc nh sn xut axit flohyric, axit xitric v tcc hthng kim sot nhim khiloi SO2 trong kh thi.

Csn xut 1 tn P2O5 axit photphoric th c 4,5 n 5 tn PG c hnh thnh v

hin nay trn tgii trung bnh mi nm c trn 150 triu tn PG c thi ra mitrng.

Thnh phn ca PG ph thuc vo qung photphat v quy trnh cng nh iu kinvn hnh khi sn xut axil photphoric. Thnh phn chyu ca PG l CaSO4nH2O (n= 0,1/2 hoc 2 ty thuc vo iu kin kt tinh ca canxi sunfat), ngoi ra cn mtlng nh cc mui photphat tan, cc hp cht ca flo, cc mui photphat ca st,nhm, cc hp cht silicat. v.v...


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PG c sdng trong mt slnh vc thay ththch cao tnhin tuy nhin cng mc hn chdo chi ph cao lm sch gip khi cc tp cht. Mc tp chttrong PG phthuc vo loi qung photphat, qu trnh sn xut v hiu quvn hnhca nh my.

Hng nm, c khong 15% sn lng gip c ti chhoc sdng li, cn li 85%

c chn lp v thi b(trong c khong 10% c thi xung bin) .

2. Thnh phn ha hc ca cc loi PG

Tt ccc quy trnh cng nghchyu trong sn xut axit photphoric c ci tinnhm mc ch thu hi lng P2O5 cao. Hin nay chyu c 3 qu trnh cng nghc bn c sdng trn th gii. Nhng qu trnh l: ihyrat, hemihyrat vhemi-ihyrat (qu trnh ny c coi l sti kt tinh ca qu trnh hemihyrat. Tytheo iu kin ha l ca phn ng gia qung photphat v H2SO4 m c th thuc hoc PG dng a - hemihyrat hoc anhyrit.

Qu trnh ihyrat (DH) c sdng rng ri trn thgii v l mt trong nhngqu trnh s dng ch yu ti M. Qu trnh ny c vn u t, chi ph vn hnhtng i thp v c tnh linh hot vsdng cc loi qung khc nhau. Qu trnhDH cng cho php sn xut c axit 28 - 30% P2O5 v cho php tch c uran.Theo phng php ny csn xut 1 tn P2O5 th to ra 4,9 tn gip kh. PG to ra tqu trnh DH c hm lng tp cht cao hn cc qu trnh cng nghkhc. Kt qu

phn tch mu PG in hnh tqung photphat v chvn hnh tt theo qu trnhDH c a ra bng 2.1

Bng 2.1 Kt quphn tch mu PG in hnh theo cng nghDH

CaO = 32,50%

SO3 = 44,00

P2O5 = 0,65

F = 1,20

SiO2 = 0,50

Fe2O3 = 0,10

Al2O3 = 0,10

H2O (kt tinh) = 19,00

Qu trnh hemihyrat (HH) sn xut axit photphoric vi hm lng 40- 52%P2O5 so vi 28-30% ca qu trnh DH. C1 tn P2O5 theo cng nghHH to ra 4,3tn PG kh vi hm lng CaSO4 cao hn. Chi ph u t v chi ph sn xut ca qutrnh HH cao hn DH. Tuy nhin, mt phn chi ph cao hn ny c cn bng li bisn phm sch hnv tit kim nng lng hn. Cho n nay cha c phng php


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hon thin tch uran tqu trnh sn xut ny. Kt quphn tch mu PG in hnhtqung photphat v chvn hnh tt theo qu trnh HH c a ra bng 2.2

Bng 2.2 Kt quphn tch mu PG in hnh theo cng nghHH

CaO = 36,9%

SO3 = 50,3

P2O5 = 1,5

F = 0,8

SiO2 = 0,7

Fe2O3 = 0,10

Al2O3 = 0,30

H2O (kt tinh) = 9,0

Qu trnh hemiihyrat (HDH) kt hp nhng u im ca qu trnh DH vi cc yu

cu vPG sch hn nh qu trnh HH. Theo phng php ny csn xut 1 tnP2O5 trong axit photphoric th to ra 4,9 tn PG.

Trong 3 qu trnh cng nghnu trn th qu trnh HDH t c sdng nht. Kt quphn tch mu PG in hnh tqung photphat v chvn hnh tt theo qu trnhHDH c a ra bng 2.3

Bng 2.3 Kt quphn tch mu PG in hnh theo cng nghHDH

CaO = 32,20%

SO3 = 46,50

P2O5 = 0,25

F = 0,50

SiO2 = 0,40

Fe2O3 = 0,05

Al2O3 = 0,30

H2O (kt tinh) = 20,0

3. Xl PG

Xl PG thi c coi l vn tng i n gin trong thi ku ca nn cngnghip phn bn, khi cc nh my c cng sut nh(thng ch25 tn P2O5/ngy,trong khi cng sut in hnh ca nh my hin nay l 1000-5000 tn P2O5/ngy) vinhng quy nh vmi trng cn cha qu kht khe.

Ngy nay cc yu cu vbo vmi trng i hi kht khe hn v vy vic thi PGra sng, bin rt hn ch. Cc bi thi PG trong t lin phi c quy hoch v chng


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thm tt nhm hn ch vic r r nc thi cha axit v cc tp cht khc ra mitrng. y l mt vn kh nan gii cho vic xy dng cc nh my DAP v MAPmi.

Bi cha PG thi phthuc vo cc iu kin cthv cc quy nh vmi trngca khu vc. Nhng bi thhin i nht c th cha c n 0,5 triu tn PG/ha

t. Ti Mv Ty u cc bi thi PG thng i hi chi ph u t cao.Bng 3.1a ra cc v dca 3 loi bi thi PG c xy dng gn y Mv Ty u.

Bng 3.1 Mt sthng skinh tca bi thi PG

Hng mc a im bi thi

USA (1) Php (2) Thy in (3)

Gi tr u t, triu USD - (1994)

Giy php v ph duytThit k, gim st

Chi ph t v san lpTrm bmTm lt (cht do)Mng thi v ph tr khcPht sinh

7,16,9

25,59,5116,99,22,8

--

12,07,942,91,6-

--

54,01,751,83,6-

Tng s 77.8 74,5 111,0

Chi ph vn hnh, USD/ tn P2O5(1994)

Ph trNhn cng v bo dngPh s dng tChi ph khc

Khu hao v ph ti chnh

0,60,64,30,7

8,2

1,16,3-0,7

8,9

0,22,80,90,8

13,7

Tng s 10,1 21,3 18,4

(1)LMC Fertilizers Inc.. Tampa, Florida - Cng sut 1,5 triu tn P2O5/nm(2)Nh ly ctrung bnh - Bi thi PG cch nh my 14 km(3)Bi thi gn nh my cnh.

Sliu so snh, nh gi vhiu sut u t v chi ph vn hnh ca cc bi thiPG tin tin trn y l khng y . Tuy nhin nh gi mt cch an ton chomi cng nghsdng th chi ph trung bnh cho bi thi PG l:

- Chi ph u t: 75 USD/t P2O5 ( 50%) - Chi ph vn hnh: 15 USD/t P2O5( 50%)


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Hthng nc ca nh my axit photphonc l mt trong nhng vn quan trng cnphi quan tm. Nc thi c sdng to bn PG bm n bi thi. Tuy nhinlng ma thng vt lng bay hi dn n chy trn nc ca ao thi .

Thnh phn ca nc hi lu trong bi thi PG c a ra bng 3.2.

Bng 3.2: Thnh phn nc ao bi thi PG

Thnh phnPhn loi

Thp (mg/l) Cao (mg/l) TB (mg/l)

P2O5FCaO/MgONa2O/K2OFe2O3/Al2O3pH

8.0009002.4005602922301,2

20.00012.0009.0005.2803.1401.5002,5

12.00010.0004.0002.4002.2504501,5

Nc trn ca ao thi phi c trung ha v lc trc khi thi . Khi thi PG ra binphi ch n tc ng ca PG n mi trng nc bin nh: nh hng canguyn thim, cht phng x, pH v.v...

4. Sdng PG

Trong cng nghsn xut axit photphoric theo phng php trch ly th trung bnh c1 tn P2O5 ca H3PO4 to ra 4,5 - 5,0 tn bn thnh phm PG (tnh theo trng lngkh). Sn lng axit photphoric sn xut theo phng php trch ly trung bnh hng

nm ca thgii l 40 triu tn P2O5 sto ra mi nm trn 150 triu tn PG, trong chkhong 15% c ti sdng.

Vic tn dng PG trong thc tin cng nghip hin vn cn rt hn ch, chyu PGc thi bng phng php chn lp. Ring ti chu u khong 90% lng PG cchn lp, 8% c ra bin v chkhong 2% c sdng cho cc ngnh kinh t.

PG c ti sdng chyu theo cc hng sau y:

- Sn xut amn sunfat (NH4)2SO4 bng phn ng gia PG vi ammac vCO2

-

Dng trong sn xut xi mng v axit sunfuric bng cch nung PG vi than ccv st (hoc dip thch).

- Lm vt liu xy dng (va thch cao, tm p, vch ngn, v.v...).- Sdng lm cht phgia cho xi mng.- Sdng lm phgia trong sn xut phn bn hoc bn trc tip v ci to mt

sloi t.- Tn dng thu hi lu hunh nguyn t.


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C thchia cc hng sdng PG theo 3 nhm sau y:

4.1. Tn dung PG thu hi gc lu hunh

4.1.1. Sdng sn xut amoni sunfat (NH4)2SO4

PG c sdng nh mt dng nguyn liu u sn xut amn sunfat (SA) theo

phng trnh phn ng sau:

CaSO4.2H2O + 2 NH3 + CO2 + H2O CaCO3 + (NH4)2SO4

Qu trnh sn xut SA theo cng nghny chyu c p dng ti n , Nga v.v...Nhn chung SA sn xut theo phng php ny t hiu qukinh t, do phi tiu tnmt lng ln hi nc c dung dch SA long thnh dng rn.

4.1.2. Sdng trong sn xut axit sunfuric v clinker

Axit sunfuric c thsn xut tthch cao (gip tnhin hoc PG), qu trnh ny c xi

mng porlan l sn phm ph. Qu trnh sn xut c tin hnh trong l quay tngtnh l quay xi mng. Phi liu cho vo l quay gm gip hoc PG ( nung dngkhan), than cc, sa thch, cc khong cha oxyt st v nhm. Phi liu phi c tnhton sao cho thnh phn cc oxyt CaO, SiO2, Al2O3 V Fe2O3 ph hp m bocht lng xi mng tt. Nhit l nung khong 1.400oC. Clinker c lm ngui,nghin mn v trn vi 5% thch cao (lm cht chm ng kt). Kh l quay c hmlng SO2 khong 5,5% c a vo dy chuyn sn xut axit sunfuric tng tnh lu trnh iu ch axit sunfuric tqung pyrit. Axit sunfuric sn phm c hmlng t96 n 98% H2SO4.

Phn ng tng cng ca qu trnh to SO2 nh sau:

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

Phn ng trn tin hnh theo hai giai on. u tin, mt phn canxi sunfat phn ngvi cacbon (than cc) to thnh canxi sunfua, theo phng trnh phn ng sau:

CaSO4 + 2C CaS + 2CO2

Tip theo nhit cao, CaS phn ng vi phn CaSO4 cn li to SO2:

3CaSO4 + CaS CaO + 4SO2

nhit cao hn, CaO kt hp cc thnh phn khc trong phi liu to thnh ccthnh phn ca clinker xi mng porlan.

Mt snh my sn xut axit sunfuric trn c ssdng thch cao c xy dngmt vi nc chu u v Nam Phi, nhng hin nay cc nh my ny bng cado khng hiu qukinh t. Khi sdng thch cao lm nguyn liu th giai on utin l khnc kt tinh n dng khan trong l nung ring bit trc. Trong giai


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on ny nu sdng PG thay gip th qu trnh nung n dng khan sc flo tch ra.Flo l yu tgy n mn mnh v rt c hi cho mi trng.

Khi sdng PG lm nguyn liu sn xut axit sunfuric, cn lu mt sim sau:

- PG (ca qu trnh DH) thng cha 15 - 20% hm m v khong 21% nc kttinh (quy kh). Do vy sphi tiu tn mt lng kh ln nhin liu nungn dng khan.

- Hm lng P2O5 trong PG phi kh thp do n c nh hng xu n cc ctnh ng cng ca xi mng sn xut tclinker ca qu trnh. p ng ciu ny, hm lng P2O5 trong PG khng c vt qu 0,5%. Mc ny nichung rt kh t cc nh my sdng qu trnh DH nhng c tht c

bng ti kt tinh trong qu trnh HH hoc HDH, hoc bng cch ra loiP2O5 ha tan.

- Flo l thnh phn khng mong mun trong phi liu ximng l quay do n lmthp im nng chy v to nn cc lp vnh ca liu trong l. PG vo l quay

phi c hm lng flo nhhn 0,15%. i a slng flo c tch ra khiPG trong qu trnh sy v nung. Ngoi ra flo cng phi c tch hon tonkhi kh l trc khi sang phn xng axit v n c thlm gim hot tnhca xc tc vanai pentaoxit.

- Nhng tp cht khc trong PG nh cc hp cht nhm, silict khng nh hngnhiu n qu trnh nung v cht lng ca clinker nhng vn phi c tnhn trong thnh phn phi liu l mt cch cn thn.

Tm li, sn xut axit sunfuric v ximng porlan trn c sthch cao tnhin hocPG c nhng nhc im c bn vmt kinh tnh sau:

(1)Tiu hao nhin liu ln nng nhit l n nhit phn ng rt cao(khong 1400oC).

(2)Chi ph u t nh my cao, qu trnh cng ngh v thit b phc tp, kchthc thit bln nn vn hnh kh hn nh my axit sunfuric theo cng nght lu hunh v nh my xi mng theo cng nghtruyn thng (nguyn liu l vi v t st).

(3)Gi thnh axit H2SO4 t: 35 - 55 USD/ tn. .

4.1.3. Tn dng PG thu hi lu hunh (S) nguyn t

Theo tnh ton, c6 tn PG th c ththu hi 1 tn S. Tn dng PG thu hi S nhngnc phi nhp khu S c thmang li li ch cao. Ngoi 2 phng php thu h i Strn c ssn xut (NH4)2SO4 v H2SO4. Vic thu hi S nguyn tcng ctnh n khi thu hi theo 2 phng php trn khng mang li hiu qu. K tnm1984, Cng ty "Petrofertil" Braxin quan tm ti h thng tn dng PG lmnguyn liu thu hi S nguyn t. Cng nghNatron ca Braxin l mt trong s cc


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cng nghthu hi S nguyn ttPG mang tnh khthi cao. Mc tiu cng nghnynhm to ra lu hunh lng v CaCO3 tPG v than .

Nguyn l cng nghgm cc bc sau:

- Tin xl, trn nguyn liu PG- KhCaSO4 bng than thnh CaS trong l quay.-

Thuphn canxi sunfua (CaS) thnh hyrosunfua nhaxit.- Cacbonat ha hn hp bng CO2 to ra CaCO3 V H2S dng kh.- Sn xut lu hunh theo cng nghthng thng i tH2S.

CaCO3 (bt nh) tinh khit c s dng trong nhiu ngnh cng nghip (sn vgiy). Kt hp sdng ccc sn phm phv hn chchi ph nng lng to iukin cho cng nghc hiu qucao.

4.1.4.Xl ng b

Nhn chung cc hng xl PG u khng mang li hiu qukinh tcao (v daxitH2SO4 sn xut tPG t hn so vi tqung pirit t1,5 - 17 ln). Gn y (1999)Vin Cng nghHa hc Ucraina a ra cng nghphi hp ng bsn xut c(NH4)2SO4 ln NH4NO3 - CaCO3 (amonicanxi sunfat) em li hiu qukinh tcaohn ng thi li thu c nguyn thim, lm cho hiu quxl nguyn liu tc gn nh tuyt i khng cn ph thi. Quy trnh cng nghny gm cc cngon chnh nh sau :

- Xl PG ngay tc ssn xut axit photphoric bng (NH4)2CO3 thu camoni sunfat (NH4)2SO4

-

Phn sau khi tch (NH4)2SO4 cn cha CaCO3 c cho x l vi axitnitric (HNO3) thu nguyn thim.

- B sau khi tch nguyn thim cng vi CaCO3 li c cho x l tip viNH4NO3 to hn hp mui cha nitrat. (c cha 60% NH4NO3 + 40%CaCO3).

Nu sn xut ng bnh trn, gi thnh (NH4)2SO4 sn phm i tPG tn dng srhn so vi sn xut vi H2SO4 i tS n 80%.

4.2 Sdng lm vt liu xy dng

4.2.1. Sdng PG lm va hoc cc cu kin xy dng

Khong 70% thch cao thin nhin c chbin thnh va thch cao, gip xp snxut tm p hoc tm vch. Va thch cao c thnh phn ch yu l thch cao c kh bt nc thnh dng cha na phn t nc (CaSO4.1/2H2O) v s tihyrat ha nhanh chng khi trn vi nc. sdng cho mc ch ny th PG nhtthit phi c loi bcc tp cht (axit tdo, cc mui photphat tan, vv...). Qu trnh


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ny phthuc vo hm lng v c tnh ca tp cht cng nh mc ch sdng cava thch cao.

Khi thch cao c sdng lm cht trt tng bn trong nh th phi c mu trngsng. Cc tp cht hu c cha trong qung photphat ban u thng gy ra mu tikhng mong mun ca PG, v vy ngi ta phi lm sch PG. C mt vi loi PG c

th lm sch tp cht loi ny tng i hiu qubng cch a bn PG qua thuxiclon thu hi phn th cha phn hu. Khi PG tng i sch th chcn ra loi baxit d. Phn d axit cn li c thtrung ho bng vi v tch nc ra bngcch lc.

sn xut tm vch th qu trnh ng cng nhanh c bit cn thit, PG vi hmlng P2O5 cao khng thch hp cho mc ch ny. PG c sn xut bng phngphp HDH thng c hm lng P2O5 thp ph hp vi mc ch sdng ny.

Bn cnh vn tp cht th mt trong nhng nhc im chnh ca PG chi dng lm

va thch cao l c m cao gy tiu hao nhiu nhin liu cho qu trnh sy kh. Dovy, ti cc nc c ngun thch cao tnhin phong ph th chbin PG lm vt liutrong xy dng t c sdng. Ti Nht Bn, nc khng c ngun thch cao thinnhin nn t lu PG c dng ch to va thch cao v cht phgia cho ximng.

Hin nay, Nht Bn l nc hng u thgii tn dng gip nhn to ni chung (mtphn l PG) sn xut va trt xut khu. Ngun gip nhn to ca Nht Bn chyu ltcc nh my pht in (thu hi SO2 tkhi nh my v chuyn thnh gip), cc cssn xut tnguyn liu u vo l photphat, cc nh sn xut titan, flo v.v... Mc

tiu thgip ni chung Nht Bn cng cao hn so vi cc nc ng Nam khc(vi con sc tnh 9,65 triu tn vo nm 1997). Tlu, Nht Bn phi nhp khuc gip t nhin ln gip nhn to t cc nc ng Nam (Thi Lan, xtrylia,Philipin), cc nc Nam M(Mexico), chu Phi (Ma rc.v.v...).

n gi nhp khu PG ca Nht Bn hin kh thp (v d nh gi nhp PG tPhilipin l 2150 yn/tn) trong khi gi nhp gip tnhin tThi Lan l xp x3.587yn/tn.

Ngoi vic phc vsn xut va trt, Cng ty Yoshino Nht Bn cn tn dng PG sn xut cc hp cht kt gn trong ngnh xy dng, cht kt dnh trong ngnh cngnghip, sn phm nng nghip, khun trang tr, phgia thc phm v.v... Theo hip hi"Gypsrum Board Asscialion" Nht Bn, mc sn xut gip nhn to Nht Bn tng t5,5 triu tn, ( 1996) ln 5,8 triu tn ( 1999) chyu dnh cho sn xut va trt phcvthtrng.

Cc cng ty USG (M) v CGC (Canaa) hng nm cng sdng hn 1 triu tn gipnhn to lm nguyn liu sn xut va trt thch cao. Cng ty "National Gypsum"hng u th gii ca M xy dng cc nh my sn xut va trt ln


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Pensylvania s dng 100% gip nhn to t nm 1997, d kin vn hnh vo nm2000. PG cn c sdng sn xut mt svt liu xy dng c bit. Chng hncc nh khoa hc M tin hnh nghin cu sn xut v ng dng cc hn hpcomposit c vai tr PG lm cht n nh dnh cho cc cng trnh bin.

Composit PG l hn hp a dng PG vi tro nh(l cn than rn hoc du t thi cc

nh my pht in c hm lng Ca cao) v xi mng porlan loi II c thcnh tranhvmt kinh tvi cc ngun nguyn liu xy dng khc. Mt sloi va trn c sPG trong c cht kt dnh anhyrit cng c cc cng ty Nga sn xut vtiu th. Bn qung, vi, PG, nc vi thnh phn hp l c em nung, nghin, lmngui (clinker anhyrit). t cng sut 400 ngn tn/ nm, mc tiu hao nguynliu cn thit nh sau:

- PG 0,995 tn

- Bn qung trung ha 0,0363 tn

- Vi 0,0363 tn

- Lignin sunfat 2.713 kg

- Kh tnhin 132 kg

-Nng lng in 110 kw/ tn/gi

Clinke anhydrit sn xut ra c a vo cc cng trnh xy dng dn dng vcng nghip hoc sn xut b tng.

Gn y, do vn mi trng nn nhiu nc chu u bt u quan tm hn nvic ti sdng PG. Cc cng trnh nghin cu vvn sn xut va thch cao rtphong ph.

Mt squ trnh sn xut cc sn phm va thch cao tPG c bit n. Nhmy chto vch ngn theo cng nghC & F Chemie cng sut 130.000 tn/ nm tiPhp. PG c sng t loi cc phn ht ln nh thch anh v c ra loicc tp cht tan v cht hu c, sau c trung ha vi nc vi v lc. Tip theogip c sy kh v nung trong mt dy 3 xiclon bng khng kh nng v nghinthnh dng bt mn.

Mt cng nghkhc do Cng ty Rhone - Poulenc pht trin hin ang sdng ti 2nh my Php vi tng cng sut 300.000 tn/ nm.

lm vt liu xy dng, qu trnh cng nghlm sch PG khng phc tp, gm ccbc thm cc ha cht (v dnh vi) trung ha axit d, gia cng nhit chuyngip sang dng na nc hoc dng khan, sau l nghin mn v phi trn u.


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Hng nm c khong 14 triu tn gip nhn to c sdng lm va thch cao hoccc sn phm trn c sva thch cao (tm p, vch ngn .v. v. ).

4.2.2. Sdng PG lm cht phgia cho xi mng

Khong 19% lng thch cao sdng lm cht phgia xi mng. Thc tngi tathm 3 - 5% thch cao lm chm thi gian ng kt ca xi mng, chng nhn, lmxi mng bn chc hn v gim sn mn sunfat. sdng PG lm phgia xi mngth cn phi xl loi bcc tp cht nh cc mui photphat tan, cc mui floruav cc tp cht hu c khc c nh hng n cht lng xi mng.

Cc kt qu thc nghim thu c mt snc cho thy PG c tc dng lm thigian ng rn cho xi mng nhanh hn so vi gip tnhin.

PG ca qu trnh sn xut axit photphoric bng phng php HH v HDH p ngyu cu lm cht phgia cho xi mng. Cn i vi PG ca qu trnh DH, th cn phic qu trnh xl tip tc nu mun dng lm cht chm ng cho xi mng. Qu trnh

ny bao gm: nung gip n dng hemihrat sau ti hydrat ha bng dung dch ncvi Ca(OH)2.Trong qu trnh ny P2O5 dng ha tan trong gip bbin thnh dngtr, ng thi cc hp cht flo cng chuyn sang dng km hot tnh. Nhu cunguyn, nhin vt liu chnh cho cng on xl 1 tn PG nh sau:

Vi sng (CaO) : 55 kg

Du FO : 45 kg

in : 15 kWh

Nga, Uzbkistan, Nht Bn, Anh, Php, H Lan, c, Phn Lan ph thi PG c sdng rng ri lm phgia xi mng.

4.2.3 Sn xut mt sloi xi mng c bit

PG c nghin cu sdng sn xut mt sloi xi mng c bit:

- Sn xut xi mng alitosunfoaluminat:

Cng ngh sn xut xi mng truyn thng tiu tn nhiu nng lng. Nh tnh chtc bit ca canxi sunfoaluminat (4CaO.3Al2O3.CaSO4) to thnh tphthi PG m

c thsn xut c loi xi mng alitosunfoaluminat (xi mng sunfo) tiu tn t nnglng, bn cao (gim tiu tn nng lng 16%, nng sut l tng 20%, gim nnglng nghin 40%) thi gian ng cng nhanh.

- Sn xut xi mng belito sunfoaluminat:


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Nu thay alito (3CaO.SiO2) bng belito (2CaO.SiO2) nh thay i thnh phn philiu cng c thto ra clinker belito sunfoaluminat c bn cao hn na trong khitiu tn nng lng thp hn na (tng ng vi vic tng sdng lng PG).

- Sn xut xi mng anhyrit II tPG - apatit (Technical University Cracow - Ba Lan)

Yu cu trc ht khi s dng PG sn xut xi mng anhyrit l phi gim hmlng hp cht photphat v flo xung (0,08% P2O5 v 0,2% F) ng thi to ht kchthc hp l.

Trong trng hp PG cn cha cnguyn thim, quy trnh cng nghca Ba Lanni trn c chia thnh hai giai on:

Ngm PG trong axit sunfuric long 12% ra thu hi nguyn thim.

Bin i PG thnh anhyrit II bng cch xl vi H2SO4 50%. Ra sn phmcho ti khi ph= 7 v nung 180oC.

Xi mng sn xut tanhyrit c cng chu nn ti a l 40 MPa sau 28 ngy.

- Sn xut xi mng siu sunfat ha tPG (University Mais - ThNh K).

Xi mng siu sunfat ha c sn xut t qu trnh nghin ln x l cao, anhyritthch cao v clinker xi mng porlan hoc vi.

chu nn ca xi mng siu sunfat ha t mc ti a (vi thnh phn trn hn hpnh sau: x l cao 85%; anhyrit thch cao 10% v clinker porlan 5%) sau 28 - 90ngy hyrat ha. y l loi xi mng bn rt cao ph hp cc cng trnh ngoi

bin.

4.3. ng dng trong nng nghip

PG l cht ci to tt cho nhiu loi t trng v l ngun phn bn cha lu hunh vcanxi.

4.3.1. Cht ci to t:

PG t lu c sdng ci to t chua cho cc mc ch nng nghip hoc gim thiu chua ca t nhng ni nc ti cha mt lng nhmui. Th dti H Lan ngi ta sdng PG ci to chua ca cc vng t ln bin dng

trong nng nghip. PG y nhanh qu trnh lc mui tt. Ngoi ra PG cn c sdng gim hm lng mt skim loi trong t (hoc l bng c chcnh hocci thin cc iu kin lc cc ion kim loi ny khi t).

4.3.2. Phn bn :

Tlu ngi ta xc nh rng lu hunh l mt nguyn tdinh dng rt cn thitcho cy trng, xp hng sau ni t, photpho v ka li. Trc y phn sc vt l mt


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ngun bsung lu hunh ng knht cho cy trng, sau phi thy ngoi ra vict than trong sinh hot (cng nh pht in) cng l mt ngun bsung lu hunhcho t. n nay ngi ta cho rng PG cng l mt ngun cha lu hunh kh ltng. a scc loi mui sunfat sdng lm phn bn u c ha lan ln nn cthbra tri khi t trc khi c cy trng hp th. Lu hunh trong PG ha tanrt t trong nc do tn ti kh lu trong t. Lu hunh di dng sunfat nn

thc vt c thhp thtrc tip. Ngoi ra PG cn cha canxi cng l mt nguyn tdinh dng cn thit cho spht trin ca cy trng. Trong cc cy trng th PG c

bit tt khi bn cho cy lc v loi ny c nhu cu canxi v lu hunh cao.

V PG thng dng t do d khng thun tin cho vic bc dchuyn chcngnh bn cho cy trng.

Mt lng nhPG c sdng lm cht bc hoc phgia trong sn xut phn hnhp NPK. Trong mt slng hp, bt PG sy kh c cho thm vo trong qutrnh to ht nhm tng bn ca ht. Ti mt snc, PG cn c to ht lm

nguyn liu trong sn xut phn trn (nh mt ngun bsung lu hunh v canxi).

Mc d c mt sng dng nu trn, song hin nay trn quy m thgii mi chmtlng nhPG c sdng trong thc tin. Trong i a strng hp th kinh thn l thi (lu) PG cc bi cha, hoc l xung bin.

Trn c scc vn trnh by vPG chng ta thy:

Vn tn dng PG khng chnhm t mc tiu kinh ttrc mt m cn phi phcvmc tiu mi trng vlu di. ph hp vi xu hng bo vmi trng toncu hin nay, nu nh bt u thit knh my mi sn xut H3PO4 theo cng ngh

t tqung photphat, chng ta nn c gng u t hp l xy dng khu sn xutng bt"A - Z" trnh cc hao ph khng cn thit. Hng gii quyt PG c thlm nguyn liu cho ngnh sn xut xi mng (cn c l nung), u t dy chuyn snxut va trt. Nu qung photphat ca ta c cnguyn thim th thm quy trnh tchnguyn thim.

TI LIU THAM KHO

1. Chang, Wen F., "Engieneering properties and construction application ofphosphogypsum" - University of Miami Press, 1990.

2. Carmichael, Jack B., Utilization of the Phosphogypsum Produced in the Fertilizer

Industry".

Vienna: United Nations Industrial Development Organization, May, 1985.

3. Erlenstadt, Gunter, "Upgrading of Phosphogypsum for the Construction Industry".


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The Florida Institute of Phosphate Research, November, 1980.

4. Kouloheris, A.K., "Chemical Nature of phosphogypsum as Produced by Various

Wet Phosophoric Acid Processes".

The Florida Institute of Phosphate Research, November, 1980.

5. Fertilizer Manual - United Nations Industrial Development Organization (UNIDO)and International Fertilizer Development Center (IFDC), 1998.

6. Phosphogypsum - Florida Institute of Phosphate Research, December 1985.

7. Industrial mineral 1/1998.

8. Khimitreskaiia Promslenost (T. Nga), 3/1999, 6/1999, 4/2001.

9. Industrial Residual management 1995.

10. Cement and concret Research 1993, 1994.

11. Utilisation des dchets.

12. Prayon Processes for Phosphoric Acid production 2001.

13. Waste materials in construction 1977.

14. Environment Science and Technological 2001.

15. Advanced Science and Technology of Sintering 2001.

16. Phosphoric Acid/Wet process: What Process? 1988.

so sánh Ưu Điểm kinh tế các quá trình trích ly h3po4 và tận dụng photphogip

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