TAP CHi HOA HOC T. 49(6) 670-673 THANG 12 N A M 2011
LAM GIAU VA LAM SACH DUNG DICH URANI B A N G HE TRAO D 6 I I O N LIEN TyC
Le Quang Thai', Vu Khfic Tuan, Trinh Nguyen Quynh, Doin Thj Mff, Nguyen Hong HA, Bui Thi Bay Vi^n Cong nghi; xa hiem, 48 Ldng Hg. Dong Ba. Ha NQI
Den Tda sogn 23-3-2010
Abstract
In uranium ore processing technology, treatment of leach liquors with a low uranium content by ion exchange is preferred. Uranium plants in the world applied many kinds of ion exchange systems, such as fixed bed column ion exchange (FBIX). resin in pulp (RIP), continuous ion exchange (CHEM-SEPS, NIMCIX, HIMSLEY, POSTER....).
Continuous ion exchange equipments that can overcome the difficulties encountered in traditional FBIX and the use of resin ion exchange for the concentration and purification of pregnant liquors have widely been used. A continuous ion exchange system similar to HIMSLEY was designed, made and a operational flowsheet wad developed to treat pregnant liquor obtained from leaching of sandstone ore. The system comprises an absorption column, an elution column and two resin transfer columns. Relent time of solution in elution column was calculated so that system can operate continuously on basis of mass balance. Operational flowsheet developed consists of distint periods: loading, elution, resin transfer and washing. Results of test showed that the system can operate well and simply. Using this system can reached uranium recovery effciency of 98%, eluale containing 11.5 g U/l.
I. MO DAU
Trong cdng nghp xir ly quang urani ngheo de thu urani ky thuat, khi sir dung tic nhan hoa tich li axit sunfuric se thu dugc dung djch cd ndng dp urani thip (thudng < 1 g/I) vi rit nhilu cic tap chat. Mac dil chiet dung mdi cd tinh chpn loc cao nhung vdi dung dich niy phuong phap trao ddi ion li lua chpn thich hpp han.
Trao ddi ion bao gdm nhieu giai doan ke tiep nhau. Trudc het, dung djch dugc tiep xiic vdi nhua, luc dd urani dugc hap thu vao nhua (giai doan hap thu), sau dd nhya dugc nia bang dung dich axit loing dl tich hit dung djch hoa tich bim theo (rua xudi), tilp theo urani dugc tich khdi nhua bang tic nhan thich hgp vi chuyen vao pha nudc (giai doan rua giii) vi cuoi cimg nhya lai dugc riia sach tic nhan (rira ngugc) vi tii sinh sin sing cho nhCrng Ian hip thu tiep theo.
Cic nhi miy sin xuat urani tren the gidi da su dyng nhieu dang thiet bj trao ddi ion nhu trao ddi ion trong biin, hp cpt nhua tTnh vi cac loai he trao ddi ion lien tyc.
Trong nhifng nam qua hp cgt nhya tmh dang nhd thudng dugc sir dyng de nghien cuu kha nang lim giiu va lim sach dung djch hoa tich quang cat kit.
Tuy nhien, neu ip dyng d quy md ldn se cd nhilu van de xiy ra nhu kich thudc cac cgt, tinh phuc tap cua hp thong dudng ong vi van, nang suit, hieu qui sir dung nhya. Vi vay, chiing tdi da manh dan thilt ke, che tao vi van hanh thir nghipm mdt he trao ddi
ion lien tyc dgng HIMSLEY cai tien cd ning suit xir ly khoing 15-20 lit dung djch hoa tach/gid. Trong bao cao nay chiing toi se trinh bay cau tao, nguyen ly van hanh, cich tinh toan thai gian luu ciia giai doan rua giai va mgt sd ket qui thu dugc khi ap dung xu ly mpt loai dung djch thu dugc khi hoi tich quang cat ket bang ky thugt trpn ii vdt axit m^nh.
2. CAU TAO THIET BI
So do cau t90 hp trao ddi ion da dugc thiet ke, chl t?o va thii: nghipm dugc md ta tren hinh 1. Cau tao ciia hp bao gom cac bg ph^n chinh sau diy:
- Cpt hap thu (V) chi thyc hipn mpt cdng vipe li hap thu urani tir dung djch vao nhya vi dam bao dung djch thai ra khdi cgt cd nong dp urani. Cpt cd dudng kinh trong 46 mm va chieu cao 1.070 mm.
Cpt chira dugc 1,8 lit nhya, chieu cao lap nhya trong cpt 1.050 mm. Nhya dugc n?p vio cpt la nhya anion bazo mgnh Amberlite IRA-420.
- Cgt rira gom 2 cgt (VI) va (VII), trong dd cpt (VI) la cpt djnh lugng nhya da bao hoa urani, cpt (VI!) la cgt djnh lugng nhya da rira giii s?ch urani.
Ngoii ehuc nang dinh lugng nhya, chung cdn diing de rira sach dung djch hoi tich keo theo nhya bao hoa (cpt VI) hay rda sgch dung djch tic nhan rira giii (cgt VII). Cgt cd dudng kinh trong 46 mm, chieu cao 353 mm. The tich nhya udt trong cpt: max 0,5 lit.
- Cpt riia giii (VIII) chi thyc hipn mpt cdng vipe la chuyin toan bg urani tijr nhya vio dung djch vi
TCHH, T. 49(6), 2011
dam bao dung dich sin phim cd nong dp urani cao.
Ve cau tao, kich thud;c cpt va lugng nhya trong cgt giong hoin toin opt hip thu.
Hinhl
- He thdng dudng dng va van: he thdng dudng dng cd dudng dung de van chuyen cic loai dung djch vio, ra he thdng, van chuyen nhua tir cic cdt hap thu vi rira giii sang cac cgt dong vi ngugc lai.
Sy ddng md cua cac van la de dinh hudng ddng dung dich vi nhya di theo chieu nhat dinh tuy theo timg giai doan.
- Bam dung djch dimg de van chuyen cac loai
Le Quang Thdi va CQng su dung djch vio hp thong trao doi ion (dung djch hoa tich, dung djch rija vi tac nhin rira giii). Theo thiet kc cd 3 bom, trong dd bam hip thu cd nang suit max la 50 lit/^d, bom hip thu cd nang suit max la 20 llt/gid vi bom rii-a vgn chuyen nhya cd nang suit max la 60 lit/gid.
- Ngoii ra cdn cd cic thimg chira de chira dung djch hoi tich, dung djch tic nhan rua giii, dung djch rira, dung djch sin phim, dung dich thai.
3. DOI T U ' O N G THlTNGHigM
Dung djch su dyng trong nghien cuu la dung dich thu dugc tir qui trinh hoa tich quang cat kit khu vyc Pi Lira (chira 0,043% U) bing k^ thu^t trpn li. Nong dp urani va cic tgp chit trong dung djch dugc dua ra trong bang dudi day. Theo sd lipu tir bing nay, ndng dp urani trong dung dich khi thip, trong khi dd nong dg cic tap chit la rit ldn. Trudc khi dua vio giai doan hap thu ciia he trao doi ion, dung djch dugc bo sung bing dung djch NaOH &k dieu chinh pH den gia trj 1,6 (phii hgp nhit cho giai doan hip thu ddi vdi dung djch hoi tich qugng).
Nhya trao ddi ion su dyng de thu nghipm li nhua anion bazo mfinh cd ten thuang mai li Amberlite IRA-420 (My). Diy li loai da dugc ip dyng d quy md sin xuit cdng nghiep tai mgt so nha miy tren the gidi.
Bk tinh toin mpt sd thdng sd cong ngh§ chinh cho trao ddi ion (chii ylu la giai doan hip thu) thi vdi loai nhua va dung dich tren day phai tiln hinh thi nghipm nhim xic djnh dugc hip dung urani ciia nhya, thai gian luu thich hgp cua dung djch khi hip thu, phin nhya bao hoa urani khi dat dilm Id. Kit qui thyc nghiem chi ra ring hip dung urani cua nhya dat 42 gU/1 nhya udt, thdi gian luu thich hgp cho giai doan hip thu li 2,5 phiit vi khi urani Id khdi cdt thi cd 1/5 sd nhya bao hoi urani.
Ndng dp cac ion trong dung djch hoa tich Nguyen to
U Fe Mg Zn Ca K Si P V
Nong dp, g/I 0,4964 4,1910 0,9261 0,6502 0,3108 0,2691 0,2041 0,1534 0,0287
Nguyen to Sr Ti Ni As Th Co Cu Cr Se
Nong dp, g/1 0,0248 0,0168 0,0113 0,0098 0,0097 0,0062 0,0050 0,0047 0,0021
Nguyen to Rb Pb Zr Ge Ga Pd Mo Sc Ba
Nong dp, g/1 0,0010 0,0007 0,0006 0,0006 0,0005 0,0004 0,0002 0,0002 0,0002 4. XAY DUKG QUY TRINH
D I dam bio myc tieu cua trao ddi ion la tich toi da tap chat, thu dugc dung djch giau urani, dim bao
hieu suit thu hdi urani cao vi giam tieu hao cic tic nhin, theo thilt kl cua hp thi mgt chu ky xu: ly dung dich bao gdm cac giai doan lin lugt thyc hien lin lugt Ii hap thu; chuyen nhya bio hoa urani ra va
TCHH. T. 49(6), 2011
dong thdi nap nhya sach vio cpt hap thu; rira nhya bao hoa urani; nap nhya bao hoa urani vio ddng thdi diy nhya di rira giai xong ra khdi cgt rtja giai va giai doan rijra s?ich nhya sau khi rira giii xong. Sau day li quy trinh thyc hipn tirng giai doan cy the:
a. Giai do^n hap ilui- dugc thyc hipn dpc l§p trong cpt hip thu, dung dich dugc bam hip thu dua vao dinh cpt, sau khi qua Idp nhya. dung djch Ihii dugc day ra d day cgt vi dugc dan tdi thimg chira dung djch thii. Chinh vl viy, cic ihao tie lan lugrt li ddng cic dudng ong thdng vdi cac cdi khic bang cac khoi tuong irng sau dd b^t bam (da dieu chinh loc dg phii hgp) rdi md khoi d diy cgt cho dung djch chiy vio thimg chira dung djch thai.
Tren ca sd cic so lipu thi nghipm da tinh loin dugc cic thdng so cdng nghp trong giai do^nn hap thu la: toe dg ddng dung djch hoa lich 272 ml/phiit, the tich dung djch hoa tach qua cgt d chu ky hap thu dau tien li 54,4 lit (do toan bg nhya trong cpl cdn mdi), cdn the tich dung djch qua cgt d cac chu ky tiep ihco li 25,3 lit (dugc tinh toin tren ca sd lugng nhya chuyen khdi cgt sau mdi chu ky) vi sau mdi chu ky thi cd 0,34 lit nhya (phia dinh cgt) bao hoi urani.
Sau khi thay thi nhya d cpt hap thu xong thi tiln hinh ngay giai doan hap thu ciia chu ky tiep theo do nang suit thiet bj phy thugc vio giai doan nay.
b. Chuyen phin nhya bao hoa urani ra, ddng thdi nap nhya mdi vio cdt hip thu dugc thirc hien ngay sau khi ket thiic giai doan hip thu vi ddng thdi vdi 3 cpt: hap thu vi 2 cdt rira. Dung dich rira (nudc dugc axit hoi din pH = 2) dugc bom vio dinh cpt rira VII, khi dd dung dich se day nhya qua diy cpl rira niy vio day cpt hap thu lim cho toin bd nhua trong cdt hap thu ding len vi phin nhya bao hoi urani tran sang cgt rua VI. De dam bao ap luc cho chuyin nhya, trii khoa thdng khi d cdt rira VI, cac dudng dng cua 3 cpt thdng vdi mdi trudng va cdt rua giii phii dugc ddng het trudc khi bit bam rira. Theo sd lieu thyc nghipm, toe dg ddng dung djch rira thich hgp li 300 mi/phiit vi khi dd dii de van chuyin hon hprp nhya vi dung dich vi han che dugc sy xio trpn nhya trong cdt hap thu. Do dd, cin dilu chinh luu lugng cua bam rua vl gii tri 300 ml/phiit trudc khi van hanh bam.
Mac dil sau mdi chu ky hip thu, lugng nhya bao hoi urani li 0,34 lit, nhung dl an toan (han chl phin nhua chua bao hoa urani tran sang cpt rira do sy xio trpn) thi mdi lan thay thi nhya chi thay 0,3 lit nhya, tuong irng vdi thdi gian thay the la 3 phiit.
c. Rira nhya bao hoi urani thyc hien dpc lap trong cgt rira VI ngay sau khi nhya bao hoi urani dugc diy sang cpt niy. Trudc hit, dilu chinh cic van dl thao dung djch trong cdt cho den khi mire dung djch cham mat Idp nhya, sau dd bam 200 ml dung dich rira vio vdi toe dg 300 ml/phiit va toan bp dung dich ra khdi cgt dugc thu ve thimg chua dung dich hoa tich. Sau dd bam tiep 700 ml dung djch rua
Lam giau va lam sgch dung djch...
nu-a, phan dung djch ra dua vio thimg chira dung djch thii, dim bio rda sgch dung djch hoi tach k^o theo nhya.
d. Ngp nhya bio hoi (di rua sgch d bude tren) vio, dong thdi chuyen phan nhya di rii:a giii hit urani cpt rira giii ra: thyc hipn dong thai vdi 3 cpt:
rira giai vi 2 cgt rira. Thao tic nay tuong ty vdi bude b d ircn, chi khic li dung djch rua dugc bam vao dinh cgt rua VI, day nhya d cgt niy vao day cgt rua giii vi phin nhya di sgch urani tren dinh cpt riia giai trin sang cgt rua VII. Thyc hipn den khi toan bp nhya trong c0t VI chuyin hit sang cgt rua giii.
c. Rira giii: Ngay sau dd, dieu chinh cic van vio vi ra ciia cgt rua giii, bgt bom rira giii cho dung djch tic nhin NaCI 1 M + HjSO^ 0,1 M vio dinh cpt rua giii, dung djch sin pham giiu urani ra khdi cpt di vio thung chtra dung djch sin pham. Cic thdng so cdng nghp nhu toe dg ddng vi the lich dung djch tic niian moi chu ky can dugc tinh toin de dim bio lugng nhya tren dinh sgch urani vi rua giat kit thuc trudc khi giai dogn hap thu ket thiic. Do vipe Igp cdng thirc tinh toin niy tuong doi dil nen trong khudn kho bii bio chi dua ra cdng thiirc tinh ip dyng cho loai dung ijljch da thu nghipm.
The tich tic nhan can thiet (V) trong mpt chu ky:
20 X^
V = —' (lit), trong dd X la lugng nhya bao hoa urani chuyen khdi cgt hap thu sau mdi chu ky, 20 la sd BV (BV li thi tich Idp nhua chua X lit) dung djch tic nhin qua cgt d l nia glil sgch urani; 1,7 la tong the tich nhya trong cgt nra giai. Vdi cic thong sd d tren, the tich dung djch tic nhan cho 1 chu ky rira giii li 1,059 lit.
Tinh toin toe dp ddng tic nhan (L): L = 0,4*XA (lit/phut), trong dd t la thdi gian liru (phiit) thyc te ciia dung djch trong cgt rua giii. Gia \x\ t phai dugc chpn nhd hon thdi gian luu cho phep eye dgi cd the du'P'c tina^. Dgi lugng t^a, dugc tinh theo cdng thirc
_ 0.68Jr.(X.Y/U/L,^„ -3.X/0,3-0.3.X/0.024-2) 20.x'
(phut).
trong dd:
Y li hap dung urani cua nhya ddi vdi dung djch thir nghipm (gU/lit);
U la ndng dp urani trong dung djch hoa tach (g/I);
Ltopii. la toe dp dong dung djch khi hap thu (lit/pliut).
Cac gia trj bang so trong cong thiic tinh la cac s6 lieu thirc nghidm.
Trong thvrc te thyc nghidm, gia tri t thuong du(K;
chpn bang 85% cua tnux la phii hprp. Nhir v|iy v6i 672
TCHH, T. 49(6), 2011
dung dich thd nghiem, tdc dd ddng khi riia giii li 0,015 lit/phiit.
f. Rura nhya sgch urani trudc khi nap vio cdt hip thu cho chu ky mdi: thuc hien d cot rua (VII) va song song vdi giai doan riia giai. Tuong ty vdi giai doan riia nhya d cpt rura VI, dung djch riia dugc bam vao dinh cot VII de thu dung dich tic nhan ve thimg chua dung dich tic nhan vi rira sach nhua trudc khi nap nhya vao cpt hip thu cho chu ky tilp theo.
Vdi quy trinh niy, dung dich sgch (sin phim thu dugc sau giai doan rira giai) cd ndng dg urani len tdi 11,5 g/1, trong khi dd sit chi cdn khoang 1 g/1, nong dp cic tap chit khic khdng dang kl. Nhu vay, mire dp lim giiu urani so vdi dung dich ban diu len tdi tren 20 lin. Dung dich thii (sau giai doan hip thu) chi chua khoing 0,011 ^U/1 bing khoang 2,2% so vdi ndng dg dung dich dau, vi vay hieu suit thu hdi urani dat khoang 98%.
5. DANH GIA KET QUA
Tren ca sd cau tao va ap dyng quy trinh van hanh he trao ddi ion lien tuc cd thi riit ra dugc mpt so uu diem ndi bat so vdi he cpt tTnh. Dd la:
- He trao ddi ion da che tgo gom 4 cpt, trong do chi cd 2 cdt Idn, trong khi do he cpt tmh can it nhat 4 cdt Idn (cd kich thudc nhu nhau). Nhira trong cot hap thu va rua giai cd the nap day trong khi do trong he cpt tmh mdi cpt can cd khoang klidng gian trdng it nhat bang 1/3 the tich cdt de sir dung khi riia ngugc. Vi the, neu nang suit xir ly ciia 2 he nhu nhau thi chic chan kich thudc cgt cua he lien tuc se nhd dang ke nen he se chiem it dien tich vi chi phi che tao thiet bj giim.
- Trong he lien tuc, cic cgt dugc chuyen mdn hda vi the he thdng van se it han so vdi he cot tTnh (mdi cpt phii thyc hien toin bp cac giai doan). Dieu niy cGng lam giim chi phi che tao thiet bj va thao tic dan giin hon.
- Trong cpt hap thu, phan nhua da bao hda urani se dugc chuyin ra khdi cgt sau mdi chu ky (trong trudng hgp thir nghiem la 0,3 lit), trong khi do vdi he cdt tinh giai dogn hap thu chi ket thiic khi toan bp nhua trong cgt bao hoa urani. Do 66, trong he lien tyc, hiu nhu toan bd nhua tham gia phan irng trao ddi ion. Mat khic, viec giii phdng nhanh lugng nhua dd din din chiing dugc til sy dung nhanh han nen khdng cin chuan bi lugng nhua ban dau Idn.
- Trong he cgt tTnh, mudn ting mire dd lam giiu urani trong dung djch sin phim cao nhu he lien tyc thi cin phii rira giai phan doan cd tuin hoin dung djch (vi du vdi dung djch da thir nghiem thi it nhit
Le Quang Thdi vd cgng su can 5 phan doan) do dd can nhieu thimg chu'a dung djch trung gian (de tuan hoan) vi he thdng dudng dng vi van s6 cing phdc tgp.
Day li nhitng uu diem noi bat, chiing chii yeu lam giim chi phi ban dau vi tgo dilu ki^n thao tic dan giin.
6. KET LUAN
Da che tgo thinh cdng thiet bi trao doi ion lien tyc nang suat 15-20 lit dung dich hda tich/gid. Thiet bj cd cau tgo don giin vi hogt ddng t6t.
Da xiy dyng dugc quy trinh van hinh he trao doi ion lien tyc. Theo quy trinh niy, ngudi su dyng cd the thao tie de dang.
Viec thir nghipm xir ly dung djch hda tich tren hp cho thay, vdi dung djch hda tich thir nghiem cd the thu dugc dung djch chu'a 11,5 gU/l (miirc dg lim giiu tren 20 lan), khoing 1 gFe/l vi mdt sd it tap chat khac. Hipu suat thu hdi urani dat 98%.
Rd ring, hp trao doi ion lien tyc cd nhiing uu diem noi bit so vdi hp cgt tTnh nen khi tien hinh xu ly dung djch d quy md Idn nen sd dyng loai thiet bj niy.
Ngoai vipe tinh toan thdi gian luu thich hop cho giai doan riia giii, trong bii da su dyng nhilu tinh toan khac nhung dugc dua vao day va se dugc trinh biy trong bii tilp theo.
TAI L I E U THAM KHAO
1 Deon van Tender, Marthie Kotze. Uranium Recovery from Acid Leach Liquors: DC or SX7, At the Alta 2007 Uranium Conference (2007).
2. Amberlite rRA-420,
http://www.suaritma.com/resms_desdown.html.
3 Alberto Castillo, Case of Small-scale Mining and Milling in Argentina Deposits, National Atomic Energy Commission), Vienna, June 2007.
4. IAEA, Significance of Mineralogy in the Development of Flowsheets for Processing Uranium Ores, Technical reports series No. 196, 74-82, 90- 100, Vienna (1980).
5. IAEA, Manual on Laboratory Testing for Uranium Ore Processing, Austria, pages 61-85; 117-118 (1990).
6. R. C. Merritt. The Extractive Metallurgy of Uranium, First printing. Library of Congress Catalog Card No.
71-157076, USA (1971).
Luiz Alberto Gomiero, Uranium Production in Caetite, Brazil, Industrias Nucleares do Brasil S/A - INB - www.inb.gov.br, Unidade de Caetite - BA, Caetitd, Bahia State - BRAZIL (2009).
Lien he: Le Quang Thai
Vien Cdng nghe xa hiem, 48 Lang hg, Ddng Da, Hi Ndi DTCQ: 38353 181; Email: [email protected].
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