Studies on the analytical geochemistry of uranium and associated elements in the Hawks Crag breccia of New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry

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(2) STUDIES OF. URANIUM. HAWKS. THE. ON. AND. CRAG. ANi�LYTICA.L. ASSOC!i..TED BRECCI1�. OF. GECYCHEMISTRY ELEMENTS NEW. IN. ZEli.Ll'.ND. A thesis. presented in partial fulfil�ent of the requirements for the degree of Doctor of Philosophy in Chemistry at. Massey Univer�ity. NOEL. EDVU;.RD. 1 969. M. Al 1 r(lllil11i iflilii llliliif 1061960755. y. COHEN. THE.

(3) ACKNOWLEDGEMENTS. The author wishes to thsnk his supervisors, Dr R. R. Brooks and Dr R. D. Reeves, for their enthusiasm and assistance throughout the work undertaken.. He is also indebted to. Dr G. Coote of the Institute of Nuclear Sciences for his assistnnce in the Gammn Spcctrometry part of the studies; to staff of the Geological Survey for vnlunble advice, to Mr Simon Nath�n, Mr John Foster and Mr Jock Braithwaite for assistance in the field work. He also wishes to thank Mrs Barbara Sanderson for typing the thesis, Miss Doreen Scott for photographic assistance and Mr Peter Herbert for printing the figures. The author is most grateful to the Mineral Resources Sub-Committee of the New Zenland Gr ants Committee for the provision of funds to support this project..

(4) Tl,BLE. OF. CONTENTS. ACKNOWLEDGEJviENTS. ii. TABLE OF CONTENTS LIST OF T.r,BLES. vi. LIST OF FIGUHES. vii. ii.BSTRl�C T. ix. GENER�L INTRODUCTION. 1. P RT ... I. DEVELOPMENT OF i,N1\LYTIC1-1L PROCEDURES. 4. I N TR O DUC T I O N. flN,.LYTICi,L PHOCEDUHES FOl\ THOHI UM , YTTR IUH ,i.ND THE R!.RE Ei.RTH ELEMENTS. 10. ( a ) O p t imum SpectroGraphic C ondi t i ons. 10. (i) Appar a t us ( i i ) S ampl e Prepar a t i on ( i i i ) R e duct i on o f Backgro und I. Inve s t i ga t i o n o f Carr i ers I I . Inve s t igat i o n of Gas Condi t i ons. 10 10 10 10 11. 13 (iv) Inve s t i ga t i o n o f S ens i t ivi t y Li mi t s ( v) The Volat i l i s a t i o n B ehavi our o f Y t t r ium , Thorium , Lan t hanum , C e r ium , Europi um, Hol m i um , Palladium, 15 and Zi rcon i um 17 ( vi ) F inal Spectrograp h i c Operating Condi t i o ns (b). S tu d i es O n T h e I n t e r f e r ence O f Tho r i um , Y t t r i um. Ana Rar e Earth �nalys i s Lines. t.. Deve lopm e n t o f an I on-Exchange S eparat ion (i). (ii ). ( c). S eparat i on by U s e o f th e Ace t ic/N i t r i c Aci d �ni on- Exchang e Sys t em S eparat i on b y U s e of the Nitric Ac i d hnion-Exchange Sys t e m. 19 19 19. 21. II. Mutual I n t e r f e r ence o f Y ttrium, Thor i um and Rare Earth �nalys i s Lines. 21. The Us e o f t he Combined �ni on-Exchange S p e ctrographic Procedure. 25. ( i ) D i s so l ut i on o f rlOCk S amp l e s (ii ) Analysis o f G-1, W-1 and CAAS S y eni t e ( i i i ) Evalua t i o n o f Data. f,N4l.LYTICflL METHODS FOR URf>NIUH (a). Spectr o graph ic Proce dur e for Macro Amo un t s of U rani um. (b). Solution Fluorimetry. ( c). Fusion-Bead F l u o r i m e t ry. 25 27 27 33 33. 33 35.

(5) 37. DISCUSSION. p;,JT. II. GEOCH;�tnc;,.L. Hi,V/I':: S. INVES TIG"TIONS CR,.G BRECC I.h.. IN. THE 39. INTRODUCTION THE GEOLOG IChL ;�ND PHYSIC i.L :.REf, ( a). Phys i c al Features. (b). General G e ol ogy. (c). FE.c�.TURES. OF THE UR.�,.NIFEROUS. The P e tr o l o gy and Mineralogy o f t h e Uran i um Depo s i ts 44. 46 47. ( i ) The N o r t h S i d e Depos i ts (ii) The S o u t h Bank D ep o s it�. 51. METHODS. (a). S ampl i ng P ro c e du r e s. (b). An�lyt i c al Tec h n i q u e s. (c). S tati s t i c al �nalysis of. ELEl'!ENTi,L ;�SSOCii,TIONS. WITH. riND SEDIMENTS. (a). C oppe r and. ( b). Beryl l i um and Uranium. (c). Lead and U ranium. (d). Z i n c and Uran i um. ( e). Rare Earth Elemen t s. 51. 53 53. Data. UR !,NIU M IN M IN ER ALS ,. SOILS. 56. U r ani u m. ELEMENTII.L Ri,TIOS A S p:,THFINDERS. 56 58 58. 58. 59 FOR. UH;�NIUM. 64 67. DISCUSSION. PA.HT III MINERf,LS BY. EQUILIBRIUM STUDIES ON URi.NIUM HIGH-RESOLUTION GAMMA S PEC TROMETRY. INTRODUCTION. 73. INSTRUMENTATION. 79. IDENTIFICATION OF S P E C TRA. 81. ( a). C a l i b r a t i o n o f Puls e H e i gh t Analys e r. 81. (b). Analys i s o f S pec tra. 81. (i). ( ii). 1 80-360 KeV Region 30- 180 KeV Reg i o n. EQUILIDRIUH STUDIES ON MINERJ,LS. 83 84 87. ( a). D e r i v a t i o n o f th& Equ i libr i um R e l a t i on s h i p. 87. (b). The Is o to p i c C o mpos i t io n o f Uranium M i nerals from the Low e r Bull e r Gorge. 91.

(6) DI SCUSSI ON. 95. GEN:Z:Ri•L DISCUSSION. 98. HEFE ..n;;NCES. 1 02.

(7) OF. LIST. T;�BLES. p,·.RT. I-1. I. Effect o f C arr i ers on Line - t o - B a c kground Raii o. of La4333 i n. a. C urbo n D i o x i de htmosph ere. 12. I -2. T i m e s for Com�l�t e Vola t i l i sut i o n o f Y t t r i um� Tho r i um and Rar e Ear t hs in Vari ous Mat ri c es. I-3. Line-to-Background R�t i o s and L i m i t s � f D e tec t i o n. for Y t t r i um , Tho r i um a n d Rar e Ear ths. 16. I-4. Spe c trograp h i c Ope r�t i ng C ondi t i ons. 18. I-5. Analy t i cal L i n e s a n d I n t e r f e r en c es. 24. I-6. R e c o v e r i es from Ion-Ex c hange S e��ra t i ons. 28. Compari s o n o f Spec tro graphi c , N e u t ro n hCt i va t i o n He c omm e n d e d Val u e s f o r Tho rium , Y t tr i um , Uranium and the Rar e Ear th s i n G - 1 , W- 1 and C:\;·,S Syen i t e. 29. I-7. 14. and. I-8. Rar e Ear th Abundan c e Ra t i o s for G - 1 , W- 1 and CAAS Syen i t e. 30. PU1T I I II- 1. S t rat igraphi c S equen c e i n L o wer Bull e r Gorge. 45. II-2. Analys i s of S tr e am S e dim e n t s as Mesh Size. 52. II- 3. Statistical Data for Various Elements in Minerals, 57. II-4. Rar e E�r t h Con c e n t ra t i o ns i n Mineral s , Matrix a n d S tr e am S e di m e n t s. 60. I I-5. El emental rtat i os a s P a t h f i nd e r s f o r Uran i um in S tr eam S e d i m e n ts. 66. I I I- 1. I s o topes and Respe c t i v e Gamma Ray Ene rgi e s used for Calibration of a Pulse Height Analys e r. 82. III-2. T h e Equ i l i b r i um S tate o f Various U ranium M i n erals from the Lowe r Bul l er G o rge. 92. a. Fun c t i o n of. S o i l s and S tr eam S e d i m e n t s.

(8) L I ST. OF. FIGURES. I-1. Spec trograms o f Rare Enr th M i xtures ( CN b and r e g i on) Arced in Var i ous Atmospher e s. pp 1 2- 1 3. I -2. L i ne- to-b ackgro und R�t i o as :trc ing Current. pp 1 4- 1 5. I-3. Vol a t i l i sation Curv e s f o r Rare Ear th s , Yt tr ium , Palladi um and Zir conium. pp1 8- 1 9. I-4. An.:1lys i s �l ement I n t en s i ty/Palladium I n t e ns i ty as a Fun c t i o n o f t h e C o e f f i c i en t o f V ar i � t i o n. pp 1 8- 1 9. I-5. Elution c u r v e s for Analys i s El e m e n t s i n Ni t r a t e pp21- 22 Sys t em. I- 6. R e c i p r o c al Di sper s i o n Ci/mm) and R e s o l u t i o n Ci) pp22 - 23 as a Funct i o n o f Wav e l e n g t h (R) for the Hi l g e r E742 Quar t z-Op t i c s Spec trograph. I-7a. pp25- 26 �orking Curves for C e rium ( 4040 ) in t h e P r e s e n c e o f var i ous c on c e n t r a t i ons o f N e o dymi um. I-7b. Work i n g Curves for Y 3327 and. I- 8. N e u t ro n Ac t i va t i o n D a t a from HASKIN and GEHL as a Fun c t i on o f Sp e c trograph i c Data from the Author for G - 1 and W- 1. pp29-30. I-9. D a t a from the Au tho r as a Fun c t i on o f Spe c t r ographi c Data from TENN.'.. NT and FELLOWS for CAAS Syeni t e. pp2 9 - 30. I-10. R ar e Ear th Dis t r i b u t i o n for an Ave rage Bas i c Rock and CA�S Sy eni t e. pp31-32. I - 11. Sp e c trographi c Wo rking Cur v e for U rani um. pp33- 34. I-12. Uran i um Fluor e s c e n c e I n t ens i ty as of Per C en t Phospho ri c Ac i d. pp34-35. I - 13. S o l u t i o n Fluori m e try Working Curv e for Uranium. pp34- 35. I- 1 4. Fus ion-Bead Fluor i m e try Working Cur v e for Uran i um. pp 3 6 - 37. a. Fun c t i o n o f. La. 3995. a. Fun c t i o n. pp25-26. Pf RT I I ... II-1. Map Show ing D i s t r i bu t i o n o f Hawks Crag Bre c c i a o n Ne s t Coas t of Sou th I s l and. II-2. Pho t o Show ing D e n s e B e e ch Fores t i n H . C . B . Ar e a pp43- 44. II- 3a. Aer ial Photograph of L o w e r Bul l e r Gorge i n c luding H . C . B . a r e a. pp43- 44. pp43-44.

(9) II-3b. Aer i al Phot ograph o f H . C . B . Ar ea from Fi g . II-3a. pp43-44. II-4. D e tai l e d G e o logi cal M ap o f th8 H . C . D . Ar ea. pp45- 46. II-5. Pho t osraph and ,:,u toradi ograph of itrkos e containing Uran i ni t e. pp48-49,. II- 6. El emen t al Rel a t i onships i n M i n erals , S o i l s and S t r e am S edim e n ts. pp57-5. II-7. Cumulat i v e Fre quen c y P l o t s f o r Var i o us El ement s i n S o i ls and S t r eam S edi m e n t s. pp58-59. II-8. Rar e Ear th D i s t r i bu t i on i n Uranium M i nerals and in S t r e am S e d i m e n t s Draining H . C . B . Ar e as. pp59-60. II-9. Triangular P l o t for C onc e ntra t i on Rat i o s of C o ppe r , L ead and Urani um in Mine rals, Soil s and Str e am S e dim ents. pp6 4-65. II- 1 0. Map of Bull e r Gorge hr ea of New Z ealand s howi ng Radioactive Horizons and Sampling P o ints for Soils and S tr eam Sediments. I I-1 1. Triangular P l o t for C on c e n trat i on Rat i o s o f Lanthanum , Ytt rium and Tho r i um from S tream S e diments i n Drai nage Areas; Ohika-Nui Riv er , O tu tu tu R i ver and Hawks C rag Bre c c i a Pi'.RT. �. pp64- 6 5. pp71 -72. III. u238, u235. 232 and Th. III-1. D e c ay S c hemes f o r. III-2. Compar i s o n o f Uranini t e Sp e c trum R e c o r d e d w i th Nai( Tl ) and Ge ( L i ) D ete c tors. pp7 6 - 77. III-3. Gamma S p e c t ro s c op y ; S c h emat i c D iagram. pp79-80. III-4. C o mp u t er - As s i s t ed Anal ys i s o f Gamma S p e c tra; S c hemat i c Diagram. pp79- 80. I II - 5. Cal i b ration Curv e , KeV as a Fun c t i on o f Channel Numb0r. pp81 - 82. III-6. I II 7 -. III-8. 232 226 Gamma Sp e c t ra of Uran i ni t e , Ra and Th Gamma Sp e c tra of Uranyl N i t rat e , Ex trac ted Uranium Frac t i on and Extrac t e d Tho r i um Frac t i on C ( 1 85 ) . as a Func t i o n o f The o r e t�cal Curve o f ( c 295 ) t h e "P erc e ntage Equi l i b rium Radium". pp74- 7 5. pp83-84 pp85- 86 pp 90- 91.

(10) hBSTRACT. Part I S tudi e s w e r e c arr i e d ou t on t h e o p t imum c o nd i t i ons f o r t h e s u c c ess ful u s e o f. a. lnrge quar t z s pe c tr ograph for t h e d e t e r m i n�t i on. o f thor i um , y t t r i um and the rar e ear ths i n s i l i c at e r o cks .. The. b e s t l i ne - t o - background rat i o s w e r e a c h i ev e d by a r c i ng s amp l e s i n a m�t r i x of 4% s odium chlor i de i n c arbon p ow d e r .. An atmosph e r e o f. 20% argon and 80% o xygen w�s us e d t o r e du c e b a ckground and e l i mi n a t � cyanogen band i n t e r f e r e n c e .. An ani o n- e xchange p r o c e dure was u s e d. t o s ep arate t h e r ar e e ar ths f r o m o t h e r e l em en t s .. T h e resul t ing. e nr i c hm e n t al l o w e d use t o be made of less s ensi t i ve rare earth l i n e s in the u l t ra v i olet end o f the sp e c trum where the sp e c t rograph i c d i s p e r s i on i s g r e a t e r .. L i n e i nt e r f e r e n c e s w e r e stud i ed and. ne c es s ary c o r r e c t i ons f o r thes e i nt e r f e r enc e s. were. c a l culat e d .. T h e t e chni que was t e s t e d b y analys i ng the s t andard rocks , G- 1 , W- 1 and CAhS syeni t e .. Depend i ng o n i ts c onc e nt r a t i o � uranium was. analys e d by e i th e r fluoram e t r i c o r spe c t rogr ap h i c t e chni q ue s . G o o d agr e e m0nt w i t h t h e r e c omm e nd e d valu e s f o r the s tandard r o cks was ob t a i ne d .. Par t I I An inve s t i ga t i o n o f t he known areas o f uranium m i n eral i z a t i o n i n the Lower Bul l e r G o r g e o f New Z e aland was c a rr i e d out to i nv e s t i ga t e the s u i t ab i l i ty o f s t r eam- s e d i m e n t analys i s for g e o c h emi c al p r o sp e c ting for uranium .. Gene ral analys i s. o f t h e m i n e r als r eveal e d c e r tain el e m e n t al as s o c i at i ons . distribution o f these. elements i n the weathering sequence,. The minerals,. s o i l s , s t r eam- s e di m en t s , was s tu d i e d i n an a t t e mp t t o di s c o v e r.

(11) s u i tabl e p3.thfind e r s for ure. n i um. s t�t i s t i cally .. Rare ear th anal ys i s. ,.11 rcsul ts were tre3. t e d of. s tr eam sadimants prov i d e d. new i n form�t i o n c o n c e rn i ng the p o s s ib l e or i�in o f. the Hawks C rag. Brc:c c i a .. P<1.r t I I I U s e was mad e o f. a. high- r e solu t i o n gamma spcc t r o m e t e r t o. s tu dy the gamma radi a t i on o f uranium m i n e r a l s i n the l ow e n e r gy r egion of the spec t rum , 30-360 KeV .. I dent i fi c a t i o n. of. the gamma. radi at i o n , in thi s r e g i o n , was a c hi e v e d by u s e of c hemi c al s ep3.ra t i cns an d s tandard s ou r c e s . d e v e lopm e n t , and s u c c e s s ful us e , o f. This p r o v i d e d the bas i s f o r the a. new m e tho d for the deter. m i n a t i o n o f " p e r c e n t age equ i l i b ri um r a d i um" .. The s i gni f i c an c e o f. the values for the "p e r c entage e q u i l i b r i um radi um" o f the m i ne rals s tu d i e d is d i s cu s s e d ..

(12) GENER�L. INTRODUCTION.

(13) 1. I n 1 95 6 , t w o pro s)e c tors , C as s i n and Jac obs e n , di s c o v e r e d ur�ni um i n t h e L o w e r Bul ler G o rge r e gion i n t h e S o u t h I s land o f N e w Zealan d .. I n t h e s e ar c h f o r radi oec t i v e m i n erals t h i s f i nd. was o f gr e at geo l ogi cal s i gni fi c an c e because i t trans fe r r ed geologi cal t h i nk i n� from the gran i tes and as s o c i�ted r o c ks t o. a. h i t her t o unsusp e c ted arko s i c b e dded fo rmat i on known as t h e Hawks Crag Br e c c i a .. T h i s di s c o v e ry b y Cas s i n and Jac obs en s t i mulat e d. t h e s ear c h f o r ur3n i um i n t h i s area u nt i l t h e early 1 960 ' s , when t h e fal l i n p r i c e of uran i um , c om b i n e d w i th unp r o m i s i ng i n i t i al f i n d i ngs, made f u r t h e r p rosp e c t i ng unat t r a c t i v e .. R e c en t l y , as a. r es u l t o f G o v er nmen t e n c ouragemen t , t h e i n t e r e s t i n uran i um p r o sp e c t i ng has b e en r e v i v e d and many o f the known ar eas o f m i n e ral i zat i on a r e b e i ng r e - e valuate d .. The n e e d for a s o u r c e o f. ur�n i um has b e en h e i gh t e n e d bec aus e o f t h e p o s s i b l e ins tal l a t i o n of. a. nuc l ear r ea c t o r i n t h e l a t e 1 970's . Prev i o u s i nv e s t i gat i ons hav e b e en c ar r i e d o u t almo s t. en t i r ely b y fi eld ge o l o g i s t s and w e r e mainly o f natu r e .. �. petro l ogi c �l. I n v i ew o f the i n c r eas ing s u c c e s s o f g e o c h e m i cal m e t hods. of e x�l o rat i0n in o t h e r par t s of the wor l d , t h e r e was c learl y a n e ed f o r s u c h an i n ves t i ga t i on i n thi s ar e a . a. The. benefi ts o f s u c h. s t udy wo u l d n o t only b e c on f i ned t o as p e c t s o f ec o nomi c geolo gy. but a l s o p r o v i de i n fo rm�t i on on the h i s tory and o r i g i n of t h e u ranium de�o s i t s and on t h e Hawks C rag Brec c i a i ts el f .. Con s i de r i ng. t he advan tag e s of geo c h emi cal ob s e rva t i on s , i t i s som ewhat surpr i s i ng that w i t h the e x c ept i o n of work by WODZICKI ( 1 959a , 1 959b ) , l i t tl e or none o f t h i s work has b e en car r i e d o u t i n t h i s area .. O n e p o s s i b l e r e a s o n f o r lack o f work i s that t h e anal y t i c al.

(14) 2.. m e t h o ds of analysing for urnnium and as s o c i a t e d e l eman t s , s u c h as t h o r i um and the rare eGr t h s , are o f t en t e d i 8us. or. unrel i abl e ,. anu r e qu i r e s p e c i al i s ed e q u i p m e n t no t generally av�i lab l e i n many · g e o c h emi c al lab or a t o ri �s . Prov i ded th�t thes e anal y t i cnl p r o blems could b e s o l v e d �nd. a. sui t abl e t e c hn i q u e c ould b e d e vel o p e d ,. o f t he a r e a w o u l d b e fac i l i tat e d .. a. g e o c hcmi c al s u r v e y. T h i s the s i s des c ri b e s somewhat. i n t en s i v e i nv e s t i ga t i ons i n t o the dev e l o pment of such t e c h n i q u e s a n d t h e i r s u b s e q u e n t a�p l i c &t i o n t o g e o c h e m i c nl s tudi e s i n t h e H�wks Crag Bre c c i a . WHI TEHE�D and BROOKS ( 1 969a ) i n r e c onna i s s an c e work i n t h e a r e a hav e h i gh l i gh t e d t h e d e f i c i e n c i e s o f many s c in t i l lome t r i c a n d o th e r rad i o m e t r i c m e th o ds f o r t h e an&lys i s o f uranium i n m i n e rals , soil s and s tr eam s e di m e n t s .. The u s e of radi omet r i c m e t h o ds f o r. ac curate quan t i t a t i v e analys i s r e l i e s o n the assumpt i on that t h e uran i um s ampl e i s i n r ad i o a c t i v e equi l i b r i um .. How e v e r ,. �. c om pr e . h ens i v e s tudy o f radi o a ct i v e equi l ib r i um i n thi s ar e� has n e v e r b e e n s a t i s fa c t o r i l y a t temp t e d , largely b e c au s e o f t h e lack o f s u i tab l e m e t hods .. Th i s prob lem was t h e r e fore i n v e s t i gated as. a. part o f t h e pr e s e n t s tudy and has been s o l v ed by the appl i cat i on of. �. n e w t e c hn i q u e i n gamma spe c tromct ry .. T h i s is rep o r t e d i n. Par t I I I o f t h i s t h e s i s . T o summar i �e , t h e a i m s o f t h i s t h e s i s w e r e t hr e e fo l d : (1). T o dev e l op a �e t h o d f o r the anal ys i s o f l o w c o n c en t r a t i ons. of y t tri um , t h o r i um and r�r e ear ths wi th the us e o f. a. l arge quar t z . o p t i c s spec t r o graph . (2 ). To i nv es t i ga t e t h e p o s s i bl e ass o c i a t i o n o f the abo v e e l e m e n t s ,.

(15) 3nd any othe r e l emen t s , w i th u ranium i n the mi nerals from t he Sou th S ide o f the Bu l l er R i v e r and t o s t u dy the d i s t r i b u t i o n o f the s e e l ements i n the weather i ng s e quenc e : m i n e ral s , s o i l s , s tr eams e d iment s .·. From thes e r e s u l t s , to examine c r i t i c ally the. r e lnt i v e m er i ts of di r e c t analys i s of uranium and of ass o c i a t e d el emen t s i n s tr eam- s e d i m e n t s , a s. a. geochem i c al prosp e c t ing method. for uran i um m i neral i z a t i o n . (3). To d e v e l op. a n d Ra. 226. a. me thod , u s i ng only gamma rad i at i o n from u. 235. , t o d e t ermi n e t h e ;'per c en t ag e e q u i l i b r i um rad i um " o f. uranium m i n e ral s ..

(16) DEVELOPMENT. OF. hN:,LYTIC .. L. PHOCEDURES.

(17) 4.. INTRODUCTION. The progress of geo chemi stry depends ulti mately on how effectivel y the c o l l ected quanti tative abundance data are utilised. The value of this informati on is very dependent on the prec i si on o f the determ inati ons and although i t i s impossi ble to assess the qual i ty of ea c h publ ished analysis, an exam i nati on o f some o f the fi gures provi ded by the vari o us m ethods m o st w i dely app li ed, d o es g i ve an i nd i c ati on of the reli abi l i ty o f much o f the exi sting data.. Furthermore, thi s also gi ves an i dea o f the pro gress in. the analyti c a l pro c edures whi c h are applied. The c lassi c al or conventi o nal meth o ds o f ro ck analysi s were fai rl y w ell estab l i shed during the sec ond half o f l ast century ( HILLEBRAND,. 1900 ) and have remai ned essenti ally unchanged. (WASHIN�TO N, 1950; GROVES, 1 951; HILLEBRAND and LUNDELL,. 1953).. Those who develop ed the classical pro cedures, as well as those who used them, frequently attempted to i n d i c ate thei r ac c urac y, b ut no real i nsight into the qual i ty o f thi s i mmense c o llecti o n o f p u b l i sh ed informati on was gai ned unti l FAIRBAIRN ET A L ( 1 95 1 ) o rgan i sed a world-w i de, inter-lab orato ry investi gati on on gra n i te (G-1 ) and d i abase (W- 1 ) .. Numerous analyses o f these ro cks were. carri ed out by a large number o f workers using a wide 9ari ety o f tec hn i ques.. The w i de variati o n i n the analyti c �l data for. i denti c al samples c learly demonstrated the shortc omi ngs exi sti ng analyti cal tec hni ques.. o f many. AHRENS ( 1 957 ) using pub l i shed. data for G- 1 and W-1 , showed that fo r c l assi cal pro c edures, the logari thm o f the standard devi ati on o f rep l i c ate analyses was i nversely related to the l ogarithm of the c o n c entrati on of the c onstituent analysed.. The si gni fi c a n c e o f thi s relati onship.

(18) b e c o m e s e x t r emely i m p o r t an t w h e n analysi ng a t t h e t r a c e el ement. ( ppm ) l evel .. For t h i s r eas o n , the analys i s of many g e o c h em i c al l y-. i mp o r tant e l e m en t s s u c h as thorium , urani um , the r a r e e a r ths and y t t r i um p r e s e n t s c ons i d e rabl e d i f f i c u l ty . S e v e ral r a d i om e t r i c m e thods hav e b e en u s e d f o r t h e d e t erminat i o n o f uran i um a n d t ho r i um ( EI CHHOLZ ET AL , 1 953; CHERRY and ADAMS , 1963; CHERRY , 1 96 3; HEIR and ROGERS , 1 96 3; VASS ILAKI ET AL , 1 96 6 ) b u t t h e s e p r o c e d u r e s s u f f e r f ro m t h e d i s adv antage t h a t radi o a c t i v e equ i lib r i um m ust b e ass um e d and this is n o t always s o .. O f t h e ab o v e worke r s , only EI CHHOLZ ET AL. ( 1 953 ) allo w e d for t h i s p os s i b i l i ty .. Fluori m e t ry ( GRIMALDI ET. AL , 1 952; PRI CE ET AL , 1 953; ANDERSON and HERCULES , 1 964 ) i s undo ub t ab l y o ne of t h e m os t s en s i t i v e me thods f o r uranium. ( l i m i t o f de t e c tion 10. -10. g ) b u t has t h e d i sadvant age that. e x t e n s i v e d i l u t i o n is n e e d e d for s amp l e s c o n t ai n i ng even m o derate amounts of t h i s el e m e n t .. O th e r m e t h o ds s u c h as. e m i s s i o n sp e c trography are by c o n tras t e x t r e m e l y insens i t i v e f o r u r an i um .. I t i s c l ear , t h e r e f o r e that a c om b i na t i on o f. m e th o d s i s r e q u i r e d i f the c on c e n t r a t i on range o f t h i s e l e m e n t spans s e v e ral o r d e r s o f magn i t ud e . Y t tr i um , t h o r ium and t h e rare earths have b e en analys e d b y X- r ay sp e c tro gr aphy ( GAVR ILOVA and TURANSKAYA , 1 958; BALASHOV ET AL , 1 96 4; ALEKSIEV and BOVADJ IJ!;VA , 1 96 6 ) , spark s ou r c e mas s sp e c t r o graphy ( BROWN and WOL STENHOLME , 1 96 4; TAYLO R , 1 965; NI.CHOLJS ET AL, 1967 ) , ac t i v a t i o n analys i s ( TOWELL ET AL , 1 965; BRUNFELT and S TEINNES , 1 966; COBB , 1 967; GORDON ET AL , 1 96 8 ) and e mi ss i o n spectrography ( FAR I S , 1 958; RADWAN ET AL , 1 96 3; MYKYT I UK 1T AL , 1 96 6; NELMS and VOGEL , 1 967 ) .. The.

(19) 6.. rel a t i v e m e r i t o f t h e s e t e chniques w i l l b e b r i e fly d i s cus s ed f o r the s ak e o f c ompl e t e n e s s al though only e mi s s i on sp e c tr ogr aphy was avai lab l e for us e at t h i s ins t i tu t i o n . has. a. X- ray sp e c t r o gr aphy. r e l a t i vely p o o r d e t e c t i on l i m i t making i t gen erally. unsui t ab l e .. Spark s o ur c e mas s sp e c tr ography has b e e n s hown t o. b e a n a c c u r a t e and e x t r emely s e ns i t i v e t e chnique and has the advantage that all elements m ay be de t er m i n e d s imul t aneously . N e u t r o n a c t i va t i o n i s a l s o e x t r e m e l y s en s i t i v e b u t r e qu i r e s c on s i d e r ab l e c h emi c al t r ea tment o f t h e s ampl e t o e l i m i n a t e i n t er f e r e n c e when u s i ng the Nai�). detec tor .. D i r e c t anal ys i s of. t h e samp l e can now b e achi e v e d us i ng the r e c e n t l y developed G e ( L i ) d e t e c to r a l t hough "co o l i ng" t im e s o f the o r d e r o f months are n e c e s s ary for s om e e l ements in o r der t o e l im i n a t e i n t e r f e r en c e p r o bl ems . Emi s s i o n s pe c tr o gr aphy has b e en f o r many years o n e o f t h e m o s t s at i s facto ry me thods f o r t h e analys i s o f rar e e a r t h s i n s i l i ca t e s (AHRENS and TAYLOR 196 1 ) .. Unfortunat ely t h i s t echn i que. n e v e r t h e l e s s suffers from c e r ta i n i n h e r e n t d i s adv an tag e s . are :. The s e. p r o duction o f hi gh backgro un d due t o the c ompl ex s pe c tra. of the rar e earths; i nt er f e r e n c e from o th e r rar e earths , t i tanium and i ro n ; the ne c e s s i ty o f h i gh amperages ( FAS SEL , 1 949; ROSE ET AL, 1 954) and l ong ar c i ng t imes b e c au s e of the relat i v e i n v o l at i lity o f t h e rare ear th o x i d e s .. This l a s t fac t o r also. r e su l t s in h i gh background due to c yanogen emi s s i on in t h e range 3500-4200. �. whe r e m o s t of the b e s t analys i s l i ne s o f the rare. ear ths are found . L i n e i n t e r fe r e n c e may als o b e r e du c e d by u s e o f a h i gh-.

(20) 7.. d i s p e r s i o n g rating i nstrum e n t an d cyanogen emi s s i o n may b e c o n t r o l l e d b y ar c i ng i n var i ous n i tr o gen- f r e e atmo s p h e res s u c h as c arbon d i o x i d e (STEADMAN, 1 94 8 ) , argon , ( VALLE�. ET. helium. or o xygen. AL , 1 95 0 ) and a m i x t u r e of argon and oxygen ( RADNAN ,. 1 963 ; TENNANT and SEV.IELL , 1 967 ) .. Us e o f a nob l e gas a tmosp h e r e. r e s ults i n a n enhan c em e nt o f i o n l i n e i ntens i t i es r e lat i v e t o tho s e o f atom l i n e s a n d a r e du c t i o n i n background .. This i s. a. d i s t i n c t advantage as the m o s t s en s i t i v e rare ear th analys i s lines ar e i o n l i ne s .. The mai n d i s a dv antage i s that ar c ing tim e s. o f t h e o r d e r o f m i nutes ar e r e q u i r e d .. Ano t h e r app r o a c h to the. p ro b l em o f l i ne i nte r f e r e n c e is the c arr i er d i s t i l l ation method ( S CRIBNER and MULL IN , 1 946; MYKYTIUK ET AL , 1 96 6 ) w h i c h all ows ar c i n g tim e s to b e r e duc e d by i n cr e as i ng volat i l i s ati on rate s . To obtai n h i gh-pr e c i s i o n quanti t ati v e r e sults , u s e o f z i r c o nium ( M c C ARTY ET AL , 1 93 8 ) , pallad i um ( YOUNG , PH . D . THES I S ) and c e rtai n rare ear th s ( FASS EL and WILHELM , 1 94 8 ; Kl'iiS ELY ET AL ,. ·. 1 95 8 ; AHRENS and TAYLOR , 1 96 1 ) as i n t e rnal s tandar ds has b e e n r e c omm e nd e d . Th e relati v ely- h i gh s e ns i t i v i ty o f rar e ear t h analys e s r e f er r e d t o i n the l i terature ( MI TC HELL , 1 94 8 ; AHRENS and TAYLOR , 1 96 1 ) was obtained v i a. a. h i gh- d i s p e r s i on i ns trument and. c annot b e dup l i c ate d w i th a quar tz- opti c s sp e c t ro graph .. The r e. i s c l e arly a ne e d fo r a m ethod whi ch w i l l p e rm i t t h e us e o f s u c h Rn ins t rum e nt i n rar e earth analys i s , p arti cul arly as s u c h sp e c trographs gr eatly outnumb e r grating i nstrum ents i n g e n e r al us e. The. majority o f the ab o v e. ch e m i c al treatment of. techniques require preliminary. the sample ei t h e r. to. reduce interference.

(21) 8. or to c o n c e ntrate the el ements b e i n g d et e rm i ne d .. S eparat i o n. meth o d s c ommonly u s e d are: prec ipitat i o n of r�re earths as hydroxides ( RO S E ET AL, 1954) extracti o n (l�cCARTY. solvent. 1946;. V A LL EE. ET fL, 1950;. ET. or. oxctl ate s (STEkDMAN, 1948),. AL,. 1938; SCRIBNER and MULL IN ,. RADWAN ET AL,. 1966) and i on exc hange ( CJ._Rm'ELL,. 1963; MYKYTIUK ET AL,. 1957; Di\.NON,. 1958; NIETZEL. E T AL , 1958; FARI S and WARTON , 1962; FR ITZ and GARRALDA , 1962; TAKETATSU, S'I'RELOW,. 1963; AHRENS ET AL , 1963; KORKISCH and ARRHENIUS, 1964;. 1966). •. It was c l e ar that a s eparati on- e n r i chment pro c e dure w o u l d b e r e q u i r e d for t h e pr e s e nt work b e c au s e o f l i ne inte r f e r e n c e s and s ensiti vity pro b l ems .. S eparati o n i s parti c ularly n e c e s s ary. whe r e s ampl e s c ontai n m o r e than five p e r c ent uranium , b e c au s e the pr e s e n c e o f a v ery l arge numb e r o f uranium l i n e s i n th e range 2500-5000 E r e s u lts i n spectra .. a. h i gh b a ckground i n the e m i s s i o n. Thi s background prev ents analys i s o f e l ements other. than uranium in thi s range . P r e l i m i nary i nv estigati ons s h o w e d that pr e c ipitat i o n and s o l v e nt extracti o n techniqu e s were unsuitab l e b e c au s e o f i n c o mp l ete r e c over i es .. Cation e xc hange chromatography was un. sat isfacto ry b e cause l �r gc e luti ng volumes were invo l v e d , with. a. s ub s e qu e nt reduc t i o n i n the c o n c entrat i o n o f th e analys i s e l em e nts .. Ani o n exc h�nge 2ppcared to b e the most prom i s i ng and. was i nv e sti gat e d furth er . The f0llo w i ng s e ct i on reports o n th e analyti c al pro c e d u r e s. w h i c h w e re d e vel oped for the analys i s o f u ranium , tho r i um , yttri um and the rare e arths i n min er a l s , s o i ls and stream s e d i m e nts , and involves:-.

(22) 9.. (i). The d evel o pment of o ptimum spec trogr aphic. operati ng c o nditions for the �nnlysis of yttrium, thorium and the rare earths, using (ii). �. medium- dispersion instrumen t .. Suitabl e methods fo r analysing uranium over. a. c o ncentratio n range o f several o r d e r s of m agnitud e . (iii). The development o f a suitabl e io n-exc hange. separation scheme for yttrium, tho r ium, uranium and rare earths in silicates..

(23) 10. ANALYTICAL AND (a) (i). PROCEDURES THE. RARE. FOR EARTH. THORIUM,. YTTRIUM. ELEMENTS. Optimum Spectrographic Conditions. Apparatus The experiments were carried out with a Hilger E742. Large Automatic Spectrograph w{th quartz optics (reciprocal dispersion 1 2 E/mm at 4000 �.). A Hilger microdensitometer. with Galvoscale calibrated in B-values (BOSWELL and BROOKS, 1965) was used for densitometry. An. image of the arc was focussed on the slit via a. quartz spherical lens and the spectra were recorded on Ilford G-30 spectrographic plates developed for. 4� minutes in Kodak. D 19b developer at 20° . (ii). Sample Preparation In all cases, solutions of thorium, yttrium and rare. earths, whether as ion-exch�nge eluants or as pure solutions, were treated in the following standard manner. A. quantity of finely-divided carbon powder (50 mg) was. added to not more than 50 ml of a solution of thoriu�.yttrium and rare earths contained in a 100 ml beaker.. The carbon powder. ( 1 20 mesh) contained an added internal standard.. After. addition of the required amount of carrier, the contents of the beaker were evaporated to dryness at 80° and the dry carbon powder was removed, ground in a motar and loaded into graphite electrodes (cavity 6mm deep and 1.5mm bore) which were dried at 130° for 2 hr. (iii). Reduction of Background I.. Investigation of Carriers. Preliminary experiments in a carbon dioxide atmosphere.

(24) 11.. were carried out on samples with and without various concentr�tions. of each of the following halides: c�esium chloride, silver chloride, sodium chloride and sodium fluoride. added to each mixture to give. a. Lanthanum was. fin al concentration of 100 ppm. and the samples were arced at 12A d.c. using anode excitation. Table I-1 shows the relative intensities of La 4333 to background for the various carriers.. From this it is seen that for an. atmosphere of carbon dioxide,. 4% sodium chloride was the most. efficient carrier for a maximum line-to�background ratio. Vclatilisation for a maximum line-to-background ratio was complete in thirty seconds, but the cyanogen emission and background, although less than that without carrier, were still too high. attempt was made. to. An. reduce these further by changing the arcing. atmosphere. II.. Investigation of Gas Conditions. Samples containing earths in. a. c a rb o n. a. mixture of thorium, yttrium and rare. matrix, with and without addition of 4%. chloride, were arced at 12;l (d.c. with. anode. s o di um. excitation)successively. in air, carbon dioxide and a mixture of argon and oxygen in varying. p r 0po rti ons from 100% argon to 100% oxygen.. This study showed. ( Fig. I-1) that a mixture of 20% argon and 80% oxygen was the most efficient for reducing cy�nogen emission and background. samples with s�dium chloride in each case had. a. The. lower background. than those without carrier but the most s tr i k i n g difference was. the considerable reduction of cyanogen emission and background with the 20% argon and 80% oxygen mixture. was quite acceptable but it sodium chloride. as. was. This level of background. necessary to know whether 4%. carrier and 12:. arcing current were in fact.

(25) 12.. TABLE. I. -. 1. Eff e c t o f C a r r i ers on L i ne-to-Background R a t i o o f L a 4333 i n a Carbon D i o x i d e Atmosp h e r e. C a rr i e r NaCl. 2% I n t ens i ty ratio. 4%. NaF. 6%. 1. 2 1.7 1.0. 2%. 4%. CsCl. AgC l. 6%. 1.3 1.0 0.8. 2%. 4%. 6%. 0.5 0.5 0.5. None. 6%. 2%. 4%. 1. 3. 1.0 0.8. 0 .5.

(26) 4% sodium chloride matrix. A. air with. B. air with carbon matrix. C. carbon dioxide with. D. carbon dioxide with carbon matrix. E. 80. 20, 0 2. Ar mixture with. F. Bo. 20, 0 2. Ar mixture with carbon matrix. Fig. I-1. 4% sodium chloride matrix. 4% sodium chloride matrix. Spectrograms of rare earth mixtures. (CN band region ) arced at 10A in various atmospheres..

(27) A. B. c. D. E. F. Fig.. I-1. Spectrograms of rare earth mixtures. (CN band region) arced in various atmospheres..

(28) 13. s t i l l t h e op t i mum conditions b o th for background redu c t i o n and sens i t i v i ty for. atmospheres. o ther than carbon d i oxi de�. It was d e c i 4e d ,. therefo r e , t o i nves t i ga t e the aff e c t o f di ff erent arci ng curre n t s , carriers. an d c arri er c o n c e n tr�t i o n s i n the 20% argo n and 80% oxyg e n. atmosphere . ( iv ). I nv e s t i ga t i o n o f Sens i t iv i t y L i m i ts AHRENS. and TAILOR ( 1 96 1 ) d i vi d e the rare earth e l em en t s. i n t o three vo lat i l i ty gro up s .. Representative. c er i um , euro p i um , ho lmium ,. y t t erb i um ) from each o f. and. e l e m e n t s ( lan thanum , these. thre e group s w ere tak e n , as w e l l as y t trium and thorium . o f the s e e l e ment s w ere prepar e d from their r e sp e c t i v e oxides.. Samples. containing 100 ppm o f each o f thes e. prep ared i n matri c e s c o n tai n i ng 2%, 4%. and. p e cpu r e ". metals were. 6% s o d i um chloride ,. s o dium fluori d e , c ae s i um c hl ori de and s i l v er ch l ori d e and wi thou t carri er .. 11S. Solutions. respectively. The sampl e s w ere ar c e d at 8A , 1 0A , 12A and. 1 4A res�e c ti v e ly ( d . c . wi th ano d e e x c i t at i o n ) i n the 20% argon,. 80% oxygen atmosphere wi th the pho t o graphi� plate bei ng racked down t o e xpose a fresh area of plat e e v e r y f i v e. seconds.. From the s e. v o lat i l i sat i o n curv e s the t i m e t ak e n f or c ompl e t e volat i l i sat ion was obtai n e d .. The results are gi v e n i n Tab l e I-2.. For the d e t erm i na t i on o f l i ne- t o -background rat i o s , a further s e t o f s amp l e s i den t i cal to tho s e ab o v e were arc e d at 8A , 10A ,. 12A an d 1 4A r e s p e c t i v e l y .. T i m e s o f arc ing were as in Tab l e I-2r. It was o bcerv e d that all carriers i n cr e a s e d the line-to-background. rat i o and i mprov e d th� d e t e c t i o n l imi t o f e a c h el ement at each o f the d i f f erent c o n c e ntrat i ons o f carri er us e d as compar e d with n o carrier .. Wi thin each carri er conc en trat i o n range , this e f f e c t. usual l y i n creas e d t o. �. maxi mum at 1 0A and 12A d e creas ing aga i n at.

(29) TABLE. •. ....-. ..::t. I - 2. T i m e s f o r C omp l e t e Volat i l i s a t i on o f Y t tr i um , Tho ri u m and Rar e Ear ths i n Var i o u s Matr i c es. Carr i e r ilg Cl. CsCl. 2% 4% 6 %. 2% 49'; 6 %. 2% 4% 6%. 35 30 25. 25 25 30. 20 25 25. 30 30 30. 35. 30 25 25. 20 20 25. 2 5 20 20. 30 2 5 30. 35. NaCl 2% 4% 6% Volatilisation time(sec) at 8 amp \I. ". ". 11. 11. n. ll. ". ". it. ". ". ". ". 11. 11. 11. il. ". ". 11. 10 12 14. 11. " il. NaF. •. N o Carrier I. 30 2 5 20. 20 20 2 5. 25 25 2 0. 2 5 30 30. 35. 2 5 25 20. 1 5 1 5 20. 2 5 20 20. 2 5 3 0 25. 35. :.

(30) 8 F ig,. I. -. 2. 10. A mps. 12. 14. Line-to�background ratio as a function of arc ing current..

(31) 15. 14A. ( F i g . I - 2) .. I t was o bserved, that 4'76 sodium c h l o r i d e and 6%. s o dium chl o r i de at. 10A. and 1 2a � e spectiv e l y p rovide d the l ar g e s t. in c r e as e i n t he l i ne-to-background rati o and i mprov ement i n t h e dete c tio n l i mit f o r eve ry element a s c ompared with no c ar r ier . R e sults o b tain e d under thesG c o nditions are sho wn i n Tab l e I-3. Th e l i m i t o f d et e c tion i s tak e n arb i tar i l y to b e that c o nc e n t r at i o n o f th e e l em e n t wh i c h w i l l g i v e a l i n e i ntens i t y equal to that o f t h e b ackgr o un d . the order o f. Sin c e th e ave rage b ac kgr o und i nt e ns iti e s w e r e of. 50. B-valu e units , the l i m i t o f de tec t i o n was taken as. that c o n c e ntra t i o n whi c h w o u l d g i v e a value o f 50 B-valu e u n i ts for t h e li n e i nt e n s i ty afte r c o r r e c tion f o r b a c kgr ound.. Tab l e. I-3 4%. sh ow s t h a t almo s t i de nti cal r esults w e r e obta i n e d with e i th e r o r 6% s o d i um chl o r i de ar c e d a t b o th 10A and 1 2A r e sp e c t i v e ly.. The fi nal choi c e of c ar r i e r concen t r a t i o n and a r c i ng amp erage was d etermi n e d b y the r e lati ve v o l atili s a t i o n r at e s of the analys i s e l em e n t s and i nt e r nal standar d .. F6r a c c ur ate , quantita t i v e. r e s u lts i t i s e s s e nt i al that t h e b e hav i o ur o f the analys i s el e m e n t s a n d i nt e r nal s tan dard b e a s s i m i l ar a s p o s sibl e.. As z i rcon i um. and pal l a d i um had b e e n u s e d b y othe r au t h o r s ( M c CARTY ET AL,. 1938;. YOUNG , PH.D. THESIS) it was d e c i d e d t o i nv e s t i gatG th eir s u i tabil i ty unde r thes e c o n d i tions. (v). Th e V olati l i s at i o n B ehav i our o f Y t trium, Thorium, L anthanum , C e r i um, Europium, Holmi um, Pal l adium and Z i r c o n ium Samp l e s c on taining. 100. ppm of t h o r i um , yttrium and each o f. t h e abov e rar e ear ths end. 1000. were. c o ntai n i ng 4% and 6% s o d i um c hl o r i d e. prepared i n m at rices. resp e c ti v el y .. ppm o f pal l a d i um and zi r c o nium. Eac h samp l e c o ntai n i ng. o f carr i e r was ar c e d at. 10A. a. par t i cular c o n c e nt ra t i on. and 1 2A i n t he. 20%. &rg o n , 80% oxygen.

(32) 16.. I. TABLE. -. 3. L i n e - t o - B a c kground R a t i o s and L imi t s o f D e t e c t i o n f o r Y t t r i um , Th o r i um and Rar e Enr t h s. Carri er 4 % NaCl A. -. 6 % NaCl. No Carr i e r. -. B. -. -. B. -. A. -. A. B. Y b32 8 9 a t 1 0 amp a t 1 2 amp. 22 . 2 33 . 8. 0.6 0. 6. 36 . 0 48 . 0. 0. 6 0. 4. 4.2 6.2. 5 5. Ho3 4 5 6 a t 1 0 amp a t 1 2 amp. 9 . 67 9 . 00. 1 .5 1 .5. 9. 5 12. 6. 3.0 3.0. 2.2 2.3. 6. 13. 4 13. 5. 0.8 0.8. 14. 1 17. 4. 1 .5 0.8. 2.9 3. 1. 5 5. Th 4 0 1 9 at 1 0 amp at 1 2 amp. 4 . 65 3 . 47. 5.0 5.0. 4. 0 3. 2. 6 5. 1.4 1 .4. 9 6. Eu 4 1 2 9 at 1 0 amp a t 1 2 amp. 9 . 00 8 . 00. 1.5 1 .5. 9. 6 8. 8. 3 1 .5. 1 .2 1 .0. 9 9. C e 4 1 33 at 1 0 amp a t 1 2 amp. 0. 81 0 . 52. 12.5 9.0. 0 . 84 o . 8o. 12.5 12.5. 0. 1 0.2. 25 25. L a 4 333 a t 1 0 amp a t 1 2 amp. 1 . 78 1 . 54. 6 6. 1 4 1. 7. 9 6. 0.5 0.2. 13 13. Y 37 1 0 a t 1 0 amp at 1 2 amp. h. B. •. •. 9. L i ne- t o - b ackgroun d r a t i o L i m i t o f d e t e c t i o n ppm ( r e l a t i v e l i n e i n t ens i t i e s g r e a t e r than 50 B-value uni t s ) ..

(33) 17 .. a tm os ph e r e. and. i n t e r v al s . s ho w s. c u r v e s o b t a i n ed ar c. The. t h a t p a l l a d i u m w as ,. z i r c on i um. f o r u s e as. an. o p t i mum ar c i ng amp e r a g e b � c au s e. unc er. volatili Ge d. these. 10A. c o n d i t i o ns. c o mp l e t e l y w i t h i n Th i s. d i ffer ent ia ted .. 4%. w i th �ll. the. t � e n ty. r e as o n. e l ements. as. The. c arr i e r ,. z i r c o n i u m hav e. e x c ep t. s e c o n ds the. t han. clos ely .. more. c h l o r i de. s o d i um. renders. f i gu r e. i t f o l l ows t h e. elemEnts. five. Th i s. e l em e n t. a better. t h e a n a l ys i s. of is. ,. s t a n d a r d as. i n t e rnal. I-3 .. s h o w n i n Fig .. c as e s. in all. V·J l a t i l i s a t i o n b ehav i ou r. too. exp o s u r e s w e r e m a d e at f i v & s e c o n d. suc c e s s i v e. w i t h o u t b e c o m i ng. o th e r. c o nd i t i o ns. less. sui tabl e .. F i n a l Spe c tr ogr aph i c Ope r a t i ng C o rtdi t i o ne .. ( vi ). Tab l e. I-4. gives. the. •. f i na l. c o ndi t i o�s. c ho s e n as. of. a r e s ul t. t h e ab o ·,r e i nv e s t i ga t i o n s . Th e th e s e of. repro duc i b i l i ty o f. w i de. d e t e rm i n e d. c o n d i t i ons was. s t andards. the. containing. s p e c t r o grap h i c. in. thor ium ,. the. A s er i e s. fol l o w i ng manne r .. y t t r i tim. T e n r epl i c a t e. a r c i ngs. wore. made. at. a n a l y ": i s. i n t ens i ty o f. each. e l em e n t. each. e ar the w i th. and r a � e. c o n c e n t r a t i o n w e re p r e p ar e d and a r c e d un d e r. l ine. us i ng. anal y s i s. the. abo � e. c o n d i t i dns .. c o n c e n t r a t i on l ev e l . and. tha t. of. the. a. The. i n t e r n al. s t andard p alladium , was m � asur ed over the c tinc e n t ra t i o n range and the r a t i o the. of. the. c o e ffi c i ent. shown . i n F i g .. to be. than. usual p r � c e dur e vari a t i o n m e a s u r ab l e. Th i s. for. �ny. Thi s. det ermined .. o f vari a t i o n. I-4.. d e t e rm i n e d. meaning ful. two was. ( pe r c e n t. curve. a l l ows. e l em e n t. at. ra t i o w as p l o t t e d. s t andard tho. any. d e v i at i o n ). c o e ffi c i ent. of. c o n c e n t r a t i o n and. aga1ris t. a nd i s v ar i a t i on is. more. t h e v � l u c o b t a i n e d f r o m a s i n gl e d e t e r m i n a t i o n . in. s u ch work. f r o m r ep l i c a t e. conc en t ra t i o n .. is. to c a l c u l a t e the c oe ffici e nt o f. anal ys e s Thi s. o f a n e l em e n t a t an. nuturally pres ents. e as i l y. v al u &s. bet ter. The.

(34) ------ -- -- ---. 18.. TABJ�E. I - 4. S p e c t ro g r ap h i c Op e r a t i ng C o n d i t i o ns S l i t l e ngth. 12. S l i t wi dth. 0 .01 5. W a v e l e n g t h range. 9 2800 - 5000 ,... Pho t ograph i c p l a t e s. I l fo r d G - 30. Current. 1 0h d . c .. mm. mm. Excit a t i on. !�nod e. Exp o s u t e. 2 5 s e c onds. El e c t r o d e s. Johns o n - M a t t h e y 4 B grap h i t e ( 1 . 5 m m i n t e rnal diam e t e r x 6 m m d e ep ) 4� m i n a t 20 ° C in K o d ak 1 9B d e v e l o p e r. P h o t ograp h i c P r o c e s s i n g Op t i c al s y s t em Arc Gas. gap. I ma � e o f a r c f o c us s e d a t s l i t w i th c o n v e x quar t z l ens. F95B. 4 mm 20% argo n/80% oxygen.

(35) Y O L A T I LI SA T I ON 4 % N aC I. = ..... -. 6 I. NaCI. ..... -. -. CURVES. 10. A. 4 % NaCI. 10. l. 6 1. hCI -. -. 12. l. 12 l. ..... .... = .... N. 50. 30. T11E. F ig ,. I. -. 3. SE C S.. 10. 20. Volat i l i zat ion curves for rare eart h s , yttr ium , pal lad ium and z ircon ium .. 30.

(36) 4. Coeff i c ient F ig .. I. -. 4. Analy s i s e lement. Of. Va r i a t io n. %. int e n s i t y / Pa l lad ium int ens i t y as a fun c t ion. of t h e coeffic ient of variat ion ..

(37) 1 9. t han can b e o b tai n e d at l o � e r c o n c e n t ra t i o n l e v el s .. (b). S tu d i e s o n the I nt e r f e r e n c e o f Thor i um , Y t t r i um and Rare Ear th Analys i s L i n e s. I . D e v e l opm e n t o f a n I o n Exc hange S epara t i o n (i). S epar a t i o n by U s e o f the Ac e t i c/Ni t r i c A c i d Ani on - Exc hange Sys t em. S o l u t i ons w e r e p r epar e d c on ta i ning macro e l em e n t s i n t h e propor � i ons fo und i n gran i t e ( G- 1 ) a s g i v e n b y FLEISCHER ( 1 96 5 ) and 1 000 ppm e a c h o f u r an i um , t h o r i um , y t t r i um and t h e rar e e a r t h s . The s ol v e n t was a m i x t u r e o f 90% gla c i a l ac e t i c a c i d �1d 1 0% n i t r i c ac i d . The anio n- e x change p r o c e dure u s e d was a m o d i f i c a t i on o f w o r k r e p o r t e d by KORK I S C H and ARRHENIUS ( 1 964 ) .. The m e th o d u s ed. w as as f o l l ows : Res i n : D o w e x 1. x. C o lumn D i m e ns i o n : Flow R ate :. 8 ( 1 00 m e sh ) , chlo r i d e form .. 1 5c m x 1 cm .. 0 . 5 - 0 . 7 ml/m i n .. Th e c olumn was p r ep ar e d i n t h e no rmal m anner as d e s c r i b ed b y VOGEL ( 1 96 1 ) a n d c onv e r t e d t o the ni t r a t e f o r m b y p a s s i n g 5 M n i tr i c a c i d u n t i l t h e e luant no longer gav e a p os i t iv e t e s t t o s i lv e r. ni t r a t e .. The c o lumn was t h e n e q u i l i b rat e d w i th 45 ml o f a. m i x t u r e o f 90% glac i al a c e t i c a c i d and 1 0% 5 M n i t r i c a c i d w h i c h h a d p r e v i ously b e e n d e gas s e d on a w a t e r pump .. The p r e v i o u s l y. p r epared m i x t u r e o f e l e m e n t s , i n t h e same s o l v e n t , w a s p as s e d t h r o ugh t h e c olumn f o l l o w e d by 5 0 m l o f t h e s a m e s ol v e n t t o r emove any w e akly- adsorb e d & l e m e n t s .. Y t t r i um , tho r i um , uran i um �nd the.

(38) 20 .. rare e arths r e ma i n e d ads o r b e d on th e r e s i n .. U rani um was s ep ar at e d. fro� tho r i um , yttr i um a n d th e rare earths b y e l uting w ith 35 ml of 6 M hydro c h l o r i c ac i d .. Thi s c o nv e rt e d the uranium i nto a. c h l o r o - c omp l e x whi c h r e ma i n e d a d s o rb e d o n the c ol umn whe r e as yttr i um , tho r i um and th e rar e earths w er e e l ut e d ns they do not form strong c h l o ro- c omp l exe s .. The urani um was then e lute d w ith. 25 ml o f 0 . 1 M hydr o ch l o r i c a c i d .. The s eparati o n to ok appr o x im at e ly. f i v e hours , b ut s e v eral c o l umns c oul d b e r un. s i multan eous l y .. In. thi s cas e a b attery o f s i x was f ound to b e s uitabl e . S ev eral exp e r i me nts w e r e c arr i e d out to i nvest i gate the e f fe ct o f f l o w rate and e l em ent c o n c e ntrati o n , e sp e c i al l y ura n i um , o n the s eparat i o n p r o c e dure .. It was foun d that the s ep arati o n. e f f i c i en c y w a s una f f e cted b y flow rates var y i ng b etw e e n 0 . 2 m l/m i n and 1 ml/m i n .. The factor g o v er n i ng f l o w rate w a s actua l l y th e. r o om temp e r atur e as the a c et i c a c i d b e c ame r ath e r v i s c ous a r o un d 1 8°C .. I n m o s t c a s e s th e f l o w rate was b etw e en 0 . 5 ml/mi n and. 0 . 7 ml/m i n .. F o r th e c o l umn d i m e n s i on s g i v e n , it was foun d that. s ol ut i o n s s amp l es c onta i n i ng up to 2500 ppm uran i um w e r e s uc c e s s f ul l y s ep a r at e d .. El ement r e c ov e ry e xp er i m ents w e r e a l s o p e r f Jr m e d. to d eterm i n e th e e f f i c i e n c y o f t h e s ep ar ati o n .. Th e r esults obtai n e d. i n d i c ated that th e r e w a s mutual i nter f e r e n c e i n the r a r e earth emi s s i on s p e c tr a , b e c aus e many e l ements gave app ar ent c o n c ent r at i ons much higher than the amounts a d d e d w o ul d h av e i ndi cate d . Although the above s eparati on s uc c es s ful ly c o n c e ntrat e s th e analys i s e l ements a n d r e mo v e s i nte r f e r e n c e f r o m m a c r o c onstituents , the r e sti l l e x i sts mutual i nte r f e r e n c e f r o m the r ar e e nrths th em s e l v e s .. R e s ults o f a n i o n e xc hange s eparat i o n s. r ep --·rted b y CARS�vELL ( 1 957 ) and DANON ( 1 958 ) i n d i c ated that i t.

(39) 21 . m i g h t b e p o s s i b l e t o s epara t e uranium , t h o r i um , yt t r i um and r a r e e a r t h s i n t o s ev eral group s , h e n c e r e du c i ng i n t e r f er en c e .. The. f o l l o w i ng i nv e s t i g a t i o n was c ar r i e d o u t . S epara t i on by U s e o f the N i tr i c A c i d Ani on. ( ii ). Exchange Sys t em U ranium , thor i um , y t tr ium and rare e a r t h s w e r e ads orb e d o n t o t h e c ol umn , as d e s c r i b ed i n t h e ab ove s e c t i o n , and w�r e , i n s epara t e exp e r i m en t s , e l u t e d w i th 2. M,. r esp e c t i v e l y ( flow r a t e 0 . 5 ml/m i n . ) . ov er. a. v o l um e o f 1 2 0 m l .. i n Fig . I - 5 .. 4 M a n d 6 M n i t r i c ac i d A l i q u o t s o f 5 m l w er e t ak e n. R e s u l t s o f the s e s ep ar a t i ons are s h o wn. From t h i s i t i s s e en th�t t h e s eparat i on i s. uns a t i s fac t o ry and fur th e r a t t �mp t s a t s eparat i o n w e r e di s c o n t i nu e d . I t i s p o s s ibl e t o s ep arat e t h e r a r e ear ths u s i ng ammonium c i t r a t e as e l u t i ng agent ( SPEDD I NG ET AL , 1 950 ) but the t i m e i nvolved r ende r e d t h i s appro a c h uns a t i s fac t o ry . An exami nat i o n. of. l i n e sp e c tra o f the anal y s i s e l e m e n t s. was t h e n m a d e i n an a t t emp t t o d e t e r m i n e the e x t ent o f m u t u a l l i n e i n t e r f e r e n c e o f t h o r i um , y t t ri um a n d t h e r a r e earths , s o that t h e s e e l e m e n t s m i gh t b e analys e d t o g e t h e r. as. a group .. r e s u l t s a r e e s s en t i Rl ly tho s e r ep o r t e d by COHEN II.. The fo l l o w i ng ET AL. ( 1 96 8 ) .. M u tual I n t e r f e r e n c e o f Y t t rium, Tho r i um and Rar e Ear t h J>nalys i s L i n e s I n t h i s s tudy i t was n e c e s sary t o know how t h e r e s o lu t i on o f. t h e l arge quar t z s p e c t r o graph vari e d w i th w av e l e ngth . d e t e rmi n e d in. two. s t eps .. Thi s was. F i r s t ly , a c u r v e of r e c ip r o c al d i s p er s i on. ( �/mm ) agai ns t wav e l ength C R ) was c o ns t ru c t e d from t h e NBS c ar d i n d e x b y m0as ur i ng t h e d i s t an c e ( mm ) ap a r t o f any t w o l i n e s a t.

(40) Yb ,. Gd ' Ho , Dy Sm. ;. ,. - - ... '\. "',. , '. en. s:::: ::J. ,. ,� ,. ,. 0. �. ,., " '. "'. L. \. .. -.....<... ', I,',• 1 , ', ' , ,,. +"'. (/) s:::: Cl). ·-. . , ,. ,. , , ,s. +"'. c:. 0. I. ,,. ·-. .... <(. I '. I ', I. 1 ·0. 1. ". I. I. ...... '. I. -. 5. ... .. ...,. .... " '. No Th detected. -- -. .. .. .... -. _... .. ,. ... .. .... \' ,. ' '. ..... '. .......... � -:... .. ,,. ., ... ,. ," ,. ': � "'. ... ... .. ... .... '-. .,'. .. - ... .... 4 M. TJ. - .... ... ... ... ... .... ... .. '. __. ..... '. .._.. ,. La. .. .. .. .... ,. .. ... __ - -. -. -. .... ... --- --. - -.* - -. - -. '. I'. -. �-. .... ,. , '· ... .... I , ' .. ' ,. ..... '. I'. )(. ,. '. ". .. ..... , ,. 2 M. I ' -.. ', ,. .... .... u. .. ..... \. .., � .... .�,.. "' ". .... ' ...... -�. '.... ... ... Th. ... _ .. ...... ..... .._... ,. ...... ,t. ..... .... "'. .,.. '. "'. '. ... ... - ... --- - -- - - - - - - - - - ::-._..,..._. 'a,. ... I 50. m ls.. Fig .. .. .. ... Nd. '. ,,. �11' ,""" , �� I I Q b -� ._.,... -- -. .... .... -. .. ... ;. ., La. '. I I I I I I. II , 1. ' � ., � 4- ,. - -. ... .... ,. Yb , Y. ;'. ,. I. · -. ... __. -- -- -.. �.. .... .. .. ... � .. " " " ,, , , "l. - - - - ..'l. - - - - - -.. -- '\. ,',- .....- ,'. ,. .... ...... ..... ,. ., ,. ,. Sm , Eu , Gd. \_,. .c. I. .- ". "" <�* ,. , "". ... Ho , Er ,. ....... -- ....�............ ,. .... ... ,... ... .. ..... '.,.J. ' ... ,'. Dy ,. ,... ,. '. ,. ,. C e , Nd ,. ro. ..... ...:: .. ,..._.... / ,. I.L.oo"". .... ' , -, ,.... ,. ".< ....... , ... , .._ I ,', !#� I.... , ,. ,' ... ... ..... ' , .... � U , .. '. M. ., ... . . .. .. ... Yb , C e. ',V/ ,', \. ',. , ,. ,. -. y,. '. '"' ....... ,. ""'. ,.. , ', ''. '. .... ... L a ", .. , ' ,'. "'. '. '. ,. ". ' •• '. Dy , Er , E u. ..... ,. .. ... ,. 'I". I. .,. >.. >.. ,'. ,. , .... ,. ,'. I. �., ,. ,. 6. - - - -y--... ,''..,. ,,. I , '. +"'. '..., ,'. I '. � '. Nd , Eu. Ce. ,, ,. I I. ·-. I. Er. ' \. y,. I. ... I 70. -. Elut ion curv e s for analy s i s elements in nitrat e system .. .... .. -.,;,- - - - - -1- - ,. 90. 1. '. ' ... .. ...

(41) 22 . a par t i c ular wav e l e ng th .. S e c o ndly , the m i n i mum d i s t an c e b e tw e e n. any t w o r e s o lv ab l e l i n e s o n the pho t o graph i c pl � t e was d e t ermin e d arb i trari l y by u s e o f t h e H i l g e r mi c ro d e ns i t ome t e r , w i th and w i thout. a. c har t r e c o r d er .. Us in g t h i s v�lu e , a curve wav e l ength. (�). T h i s d i s t an c e was found to b e abo u t 0 . 04mm . r e s o l u t i on ( A ) as. of. �. was c o n s t ru c t d .. fun c t i o n o f. a. I t i s i mpor tant t o add that the. t e rm r e s o lvab l e , as us e d pr e v i o� s l y , m eans that it was just pos s i b l e t o d i s t i ngui s h t w o s eparat e peaks a n d d epends s omewhat arb i trar i l y o n t h e a c u i ty o f t h e o b s erver .. F i g . I - 6 s hows t h e r e spe c t i v e curves .. From th e s e f i gu r e s i t w as pos s i b l e t o d e t e rm i n e. a. po t e n t i al i n t er. f e r e n c e band of wavel engths on e i ther s i de of any par t i c ul ar an3l y s i s l in e a t any par t i cular w av e l ength .. From NBS Tab l e s. ( MEGGERS ET AL , 1 96 1 ) po s s ib l e int e r f e r i ng rare e a r t h el e m e n t l i n e s may b e f ound .. The e x t e n t t o whi c h t h e e l em e n t s i n t e r f e r e c a n b e. ob t a i n e d app r o x i ma t e ly from t h e formula. % I n t e r f e r en c e. =. 1 00 x A i I i Aa I a. where A i , A a are t h e r e spe c t i v e abundan c e s o f the i n t e r f e r i ng and analys i s e l em e n t s and I i and I a are t h e r e spe c t i ve l i n e i n t ens i t i es .. I t mus t b e emp has i s e d t h � t i f i n t e ns i ty values from. the NBS Tab l e s ar e u s e d t o c ompu t e t h i s i n t e r ferenc e , the r e s ul t s may b e d i f f er e n t from tho s e o b t a i n e d w i th e xper i m ental c o nd i t i ons di f f e r e n t from tho s e us e d by t h e au t h o r s of the s e tabl e s . To c h e c k t h e val i d i ty o f thi s fo rmula under t h e c o ndi t i ons u s e d , s eparat e s o lu t i ons were pr epar e d from 11Spe c pur e " c h em i c al s for y t t r i um , t h o r i um and e a c h l an thani d e .. S epa rate s amp l e s c on . t a i n i ng 1 00 ppm o f e a c h e l e m e n t w e r e p r epar e d a n d a r c e d under t h e.

(42) t:. 1 ·2. E 24 1--. �. 0. c 0 tn. 20. L. I. .... Cl) 16 Q. tn. l. /. ·-. c. -. CO CJ 0 .... . Q.. ·. 1·0. ll; o.J o. 0·8. <( --. c . o. 0· 6. -. 0 tn Cl) a:. /. sl. I. -. CJ Cl) a:. 0·2. 4 1- / I 3 000. 0I. I. I 4000. I. I .I 5000. Wave lengt h Fig .. I. -. 6. Rec iprocal D ispers ion ( �/mm ) and Resolut ion Hilger E742 quart z-optic s spectrograph .. I 3000 0. (A) (�). I. I 4000. I. I 5000. l. as a function of Wavelength ( R ) for the.

(43) 23.. s t andard c o n d i t i o ns .. The i n t e ns i t y o f n n analys is l i n e f o r e a c h. e l e m e n t w a s m e a s u r e d t o g e ther w i t h t h e i n t en s i t y o f any p o t e n t i al ly i n t e r f er i ng l i n e s o f o th e r e l e m e n t s .. Th e d ata show e d th�t f o r a. p r e d i c t e d i n t e r f 6 r e n c e o f up t o 1 0% , no i n t e r f e r en c e was d e t e c t e d i n t h e spe c t rum o f any o f t h e s e e l em en t s a t t h e wavel e ngth o f the s e l e c t e d analys i s l i n e s .. This wa s no t the cas e f o r p r e d i c t e d i n t e r . f e r en c e s gr e a t e r t han 1 0% . u s e d fo r y t t r i um ,. Tabl e I - 5 l i s t s t h e analys i s l i n e s. t ho r i um a n d t h e r ar e ea r th s w i th t h e r e sp e c t i v e. i n t e r f e r i ng l i n e s o f o t h e r rar e e ar th e l e m e n t s and i n t e n s i t y r a t i o s f o r sub s e qu e n t c o r r e c t i o n .. Th e analy s i s l i nes t e s t e d ar e no t. always t he r e c omm e n d e d R. U . l i n e s b u t i n s o m e c a s e s are l i n e s o f l o w e r w a v e l e ngth whi c h , a l t h o ugh o f l o w e r s en s i t i vi t y , may s t i l l b e u s e d b e c au s e o f t h e i o n e x c hang e en r i c hm e n t and s ep ar a t i o n p r o c edur e .. This u s e o f l o w e r wav e l ength l i n e s has t h e o b v i o u s. ad vant age o f b e t t e r r e s o l u t i on s i n c e d i sp e r s i o n i n c r e a s e s w i th d e c r eas i ng w av e l e ng t h .. Th e t �b l e d o e s no t l i s t �ll th e p o s s i b l e. i n t e r f e i i ng l i n e s a s g i v e n i n t h e NBS Tab l e s b u t o n l y t h o s e whi c h give. a. p r e d i c t e d i n t e r f e r e n c e o f m o r e t h 3 n 1 0% from th e formula. ( c o n s i de r i ng the norm al abun d n n c e r n t i o s of the s e e l e m e n t � ) and wh i c h w e r e d e t e c t e d i n t h e s p e c trum of the p u r e e l e m en t . c ns es ,. I n all. t h e h ighe s t l i ke l y c o n c e n t ra t i o n of t h e i n t e r f er i ng e l e m e n t. w a s t a k e n i n o r d e r t o allow f o r maxi mum i n t e r f e r e n c e po s s i b l e . Wh en s igni f i c ant i n t e r f e r e n c es arc o b t ai ne d , c o rr e c t i o n s a r e m a d e as iri t h e f o l l o w i ng e xamp l e .. 4040 . 80. �. As the n e o dym i um l i n e a t. i n t e r f e r e s w i th c e r i um 4040 . 7 6. i n t e r f e r e d w i th , was found. to. �. ( t h i s l i n e , al tho ugh. be the m o s t s u i t ab l e c er i u m l i n e ) ,. t h e i n t en s i t y ra t i o o f t h e n e o dymium l i n e s a t 4040. �. and 406 1. i n the ab s e n c e o f c e r i um , wns m e a s u r e d nnd found to b e 0 . 7 3 2 .. �' The.

(44) T,·.BLE. .. ..:t (\). I - 5. Analyt i c al L i n e s �nd I n t e r f er e n c e s �nal � t i � al l i � e � i n i > ( ln t en�:n t l. e s ) * Lu 2 9 1 1 . 3 9 ( 6 00 ) Yb 3 2 8 9 . 3 7 ( 2 6 00 ) Tb 33 2 4 . 40 ( 400 ) y. 33 2 7 . 8 9 ( 6 00 ). P d 3 42 1 . 24 ( 1 400 ) * * Gd 3 4 2 2 . 57 ( 7 00 ). H o 3 4 5 6 . 00 ( 1 80 0 ). Tm 3 4 6 2 . 20 ( 800 ) D y 3 53 1 . 7 0 ( 2000 ). I n t er f .:? r e n c e range A ( f rom Fi g . I - 6 ) +. 0. 1 8. � 0 . 27. � 0 . 27. � 0 . 27. � 0 . 30. � 0 . 30 � 0 . 31. � 0 . 32. � 0 . 33. I n t e r f e r ing l in e s i n � ( i n t e ns i t i 0s ) *. I n t en s i t y ra t i o s o f i n t e r fering lines and reference l i ne s. Th 2 9 1 1 3 2 ( 8 ). Th 2 9 1 1 /Th40 1 9. None. None. None. None. None. None. None. None. None. None. None. None. None. None. None. None. •. Er 3 6 9 2 . 6 4 ( 7 00 ). � 0 . 38. None. None. L a 3 9 95 . 75 ( 3 6 0 ). +. 0 . 48. None. None. C e 40 1 9 . 04 ( 1 4 ). C e 40 1 9/C e 4o4o. N d 4o4o . 8o ( 1 8o ). N d 4040/Nd40 6 1. None. None. C e 41 79 . 29 ( 5 ). C e 4 1 7 9/C e 40 1 9. None. N o ne. C e 425 6 . 1 6 ( 1 2 ). C e 425 6/Cc4o4o. Th 4 0 1 9 . 1 3 ( 3 00 ) C e 4040 . 7 6 ( 1 50 ) N d 4 0 6 1 . 09 ( 280 ) Pr 4 1 7 9 . 42 ( 4 6 0 ). �u 4 2 05 . 05 ( 4000 ) S m 4 2 5 6 . 3 8 ( 1 40 ) * In t en s i t i e s from NBS T a b l e s * * I n t e rnal S t �n dard. � 0 . 50 :t 0 . 50. :t 0 . 50. � 0 . 55 .±. 0 . 57. .±. 0 . 59. 0 . 02 7. =. =. =. 0 . 2 37 0 . 7 32 I. =. 0 . 07 6. =. 0 . 092.

(45) 25.. c o r r e c t e d c er i um i n t e ns i ty a t 4040. 7 6 R i s o b t ai n e d b y s u b t ra c t i ng 7 3% o f t h e n e o dym i um i n t s n s i t y a t 40 6 1 . 09 � ( i n t e r f e r e n c e fr e e ) from the obs e rv e d valu e for the c e rium l i ne . The c o r r e c t i o n o f anal y s i s l i n e s for i n t er f e renc e s h o u l d b e carr i e d o u t i n the f o l l ow i n g s e quenc e .. C e 4040 i s c o rr e c t e d f o r. N d 4040 i n t e r f e r en c e , f o l l o w e d b y c o r r e c t i on o f T h 40 1 9 f o r C e 40 1 9 , u s i ng t h e c o r re c t e d C e 4040 i n t e ns i ty value t o c al cu l a t e Having o b t a i n e d i n t e r f er enc e - f r e e. t h e c o rr e c t value f o r C e 40 1 9 .. C e 4040 a n d T h 40 1 9 i n t ens i t i es , P r 4 1 7 9 c �n b e c orr e c t e d f o r ·. n� e>dymi um , c e r ium and tho r i um i n t e r f e r en c e s . W o rking curves for i n t er f er en c e- f r e e e l ements c an b e p r ep a r e d by dilution of. a. c ommon m i x e d s tandar d , b u t o th e r w o rk i ng c u r v e s. mus t b e p r ep a r e d f r o m i n d i v i dual unm i x e d s tandards .. Fig . I-7a. shows t h e working c u r v e f o r C e 4040 i n t h e p r e s en c e o f var i o u s c o n c e n t r a t i o ns o f n e o dymium , w i t h a n d w i thout c o r r e c t i o n , and t h e curve o b t a i n e d f r o m a p u r e c e r i um s t �ndnr d . o th e r e l e m e n t s ( F i g . I - 7 b ) a r e a l s o g i v e n .. W o rking curves f o r The l ow s c a t t er o f t h e. p o i n t s g i v e s a n i nd i c a t i on o f t h e p r e c i s i o n o f the m e th o d . (c). The U s e o f the Comb i ne d An i o n Exc hange Spe c tr ographi c P r o c e dure. (i). D i s s o l u t i o n o f R o ck Sampl e s The e a s e w i th w h i c h r o cks a r e d i s s o l v e d d ep en ds p r i mar i ly. o n t h e n�ture o f t h e r o ck ( s i l i c a t e , sulphi d e e t c . ) , t h e e l e m e n t s p r e s en t , and t h e s o l v e n t us e d .. The s o l v e n t r e qu i r e d for t h e ani o n. e x c hange s ep ar a t i o n , i n t h i s c as e , g o v e rn e d t h i s c ho i c e a n d h e nc e p r e s e n t e d c e r ta i n d i f f i c ul t i e s .. T h e main o n e was t h a t 90% g l a c i al. a c e t i c a c i d and 1 0% 5 M n i t r i c ac i d i s an e x t r em e l y p o o r s o l v e n t ..

(46) 1· 0 0. a. 0 ·1 0. Ce. Nd. =. 1. 1. b. Ce. Nd. =. 3. 1. C. P,ure Ce. cl. Corrected. 10. 1 00. C e r i um F ig , I. -. 7a. and B curves for Nd interference. A. }J9. Working curve s for cerium ( 4 040 ) in the pre sence of various concentrat ions of neodymium ..

(47) y. 3327. La. 1 00. 10. ).1 9 Fig . I. -. 7b. Working curve s for Y 3 3 2 7 and La3 9 9 5 .. 3 99 5.

(48) 26 . A lso , the el ements tho r i um and c e ri um are generally v e r y i nsoluble e v e n in m i n eral acids .. As. a. resul t , the fo l lo w i ng r a t h e r t e di ous. s c h e m e had to be use d . C o n c e n t ra t e d n i t r i c a c i d and c on c e n t r a t e d hydr o flu o r i c a c i ds ( 1 5 ml o f e ach ) w e r e added t o 1 g o f f i n e ly- d i v i d e d r o c k sample ( 1 20 m esh ) i n a p er i o d. a. 250 ml t e flon. o f 2- 3 hr .. b e ak e r. nnd evap o r a t e d t o dryness o v e r. Then 1 5 ml o f c on c e n t r a t e d n i t r i c a c i d was. add e d to t h e r esi du e , whi c h w as n e x t t r an s f e r r e d to b e ak e r and slowly e v ap o r a t e d to dryness.. a. 1 50 ml glass. To this residue was. adde d 1 5 ml o f 9 : 1 m i xture o f glac i al a c e t i c a c i d and 5 M ni t r i c ac i d ,. and t h e w ho l e was t ransf e r r e d t o a tube and c e n t r i fuge d .. The. sup e r n a t an t l i qu i d w as r e t a i n e d and the r esi due was agai n t r e a t e d w i th 1 5 ml o f c onc e n t r a t e d n i t r i c R c i d , evap o r a t e d t o dryn e s s , t aken up i n 1 5 m l of ace t i c acid- n i t r i c a c i d m i x ture and c en tr i fuge d . The solu t i o n was r e t a i n e d and t h e r esi due ( usually l e ss than 0.3 g ) w as dr i e d , w e i gh e d , m i x e d i n a 1 : 3 rat i o w i th so d i um p er o x i d e and fused i n a pla t i num c ru c i b l 2 at 480 ° for s ev en m i nut es ( RAFTER , 1 950 � . The melt was n e u t r a l i s e d w i th n i t r i c a c i d and the so lu t i o n cen t r i fuge d .. Any sol i d r emai n i ng. was. d i s card e d .. S u f f i c i en t. g l ac i al nce t i c aci d t o g i v e t h e c orr ect r a t i o o f a c e t i c aci d t o n i t r i c a c i d w as added and all t hr e e sup ernatants w e r e c o mb i ne d . Th e t o tal vulumc was usually 70- 80 ml .. The so lu t i o n w as degassed for. twe n t y m i nu t es and t h e n t r �nsf e r r e d t o t h e p r epar e d i on- e x c hange c o lumn .. Comp l e t e d i gest i o n o f t h e nnalysis el ements was c o n f i rm e d. b y a r c ing t h e sup e r na tants and r e sidue o f a t est samp l e a f t e r e ach s t age had b e en c o mp l e t e d ..

(49) 27 . (ii). Analys i s o f G- 1 , W - 1 and CAAS S yen i t e To e va l u a t e t h e c omplet e an�l y t i c al pro c e dur e , experim e n t s. w e r e c arr i e d o u t to t e s t t h e r e c o very o f e l e m e n t s from t h e i o n exc hange c o l umn .. Tab l e I - 6 shows t h e r e s u l t s ob tai n e d f o r s o m e. r ep r e s e n t a t i v e e l e m e n t s c ar r i e d thro u gh a c o mp l e t e s ep�ra t i o n and. analys i s pr o c e dur e .. Analys i s o f the s t an d ard r o c ks G- 1 , W- 1 and. C A�S S y e n i t e for thor i um , y t tr i um and rare earths was c arr i e d o u t b y t h e d e v e l op e d p r o c e dur e .. Tab l e I - 7 c ompares t h e r e s ul t s o b t � i n e d. w i th the mo s t r e c e n t r � c omm e n d e d valu e s . (iii). Evalua t i o n o f Data The agr e e m e n t b e tw e e n the s p e c t ro grap h i c r e s u l t s o b t ai n e d. i n t h i s w o rk f o r G- 1 and W- 1 and tho � e g i v e n by FLEISCHER ( 1 9 6 9 ) are go o d .. The n e u t ro n ac t ivat i o n d a t a o f HASKIN and GEHL ( 1 96 3 ). als o c o r r e l a t e s e x t r e m e l y w e l l and i s shown i n F i g. I - 8 . Th e values o b t a i n e d f o r CAAS S y e ni t e give f r e s h data f o r n i n e r a r e e a r t h e l e m e n t s who s e v cl. u e s , as r ep o r t e d b y WEBBER ( 1 96 4 ) w e r e e i t h e r doubt ful o r w e r e b el o w t h e d e t e c t i o n l i m i t o f t h e t e c hn i qu e s us e d .. The r e c e n t s ummary o f S I N� E T A L ( 1 96 9 ) i n cl u d e s. v�l u e s o b t � i n e d b y TENNANT a n d FELLOWS ( 1 9 6 7 ) , a l s o u s i ng emi s s i o n s p e c trography .. The s e valu e s gen erally c o r r e l a t e w e l l w i th t h i s. w o r k and a r e s ho wn i n F i g . I- 9 .. Th i s f i gure s shows t hat t h e r e i s. d i s ag r e e m e n t i n t h e values for s amar i um , h o l m i um and lut e c ium .. In. o r d e r t o e valu a t e the c o rr e c tn e s s o f t h e valu e s o b t ai n e d , t h e r� r e earth abundan c e rat i o s for a n average a c i di c ro ck , a n average b as i c r o c k and C�AS S y e � t e w e r e c al c u l at e d . Tab l e I - 8 .. These val ues are g i ven i n. � �i s t ab l e shows that w h e n ever t h e r e s u l t s o f t h i s w o rk. and t ho s e o f Tennant and F e l l ows agr e e , the abundan c e ra t i o ( normal i s ed t o La = 1 . 00 ) o f t h e rar e earths in t h e sye ni t e.

(50) 28 .. TABLE. I. -. 6. R e c o v e r i e s from I on-Exchange S epar � t i o ns. El em e n t. J>moun t a dded ( fl. g ). ,'-•mount r e c ov e r e d ( �g ). La. 300. 280. Ce. Nd. 300. 309. 300. 309. Sm. 1 00. 1 02. Eu. 1 00. 98. 1 00. 99. Dy. 1 00. 1 02. Ho. 1 00. 1 02. y. 1 00. 1 00. Gd.

(51) TABLE. .. 0' (\j. I. -. 7. CoQpar i s o n o f Sp e c tr o graphi c , N e u t r o n A c t i v a t i o n and R e c o mm e nded Values f o r Tho r i ua, Yt trium , U r an i um and t h e Rare ear ths i n G- 1 , W- 1 and ChhS Syeni t e ( ppm ). Code La Ce. Pr N cl Sm Eu Gd Tb Dy. 1 2 3 4 5 6 7 8 9. Ho. 10. Er Tm Yb Lu. 11 12 13 14 15. y. Th. u. A. B. c. 1 00 200 19 60 < 5 0.9 7 < 2 2 0.4 1.4 < 3 0. 6 0. 1 12 30 2.6. 80 1 60 16 43 c: 1 0 1 <: 1 0 < 50 < 20 < 1 <. 1 0 <: 1 0. 8 .c 1 0 12 21 < 50. 1 00 1 70 17 55 9 1 .3 5 0.6 2.5 0. 5 2 0.2 1 0.2 13 52 4. l'l. D 1 02 1 34 20 . 9 54 . 6 8.6 1 . 04 4 . 88 0. 5 n. d. 0.5 1.4 0. 2 0 . 62 0 17 12.5 n . d. n.d. .. 10 20 5 16. � 5. 1.5. 4 < 2 2 3 2.5 < 3 1 .5 0.3 11 1 1 .5. c 12. D. 1 1 .7 24 23 3 . 68 4 17 15. 1 4 3 . 79 1 1 1 . 09 4.2 4 0 . 75 0.8 n.d. 4 1 . 35 1 2 . 57 3 0 . 35 0.3 2. 1 2.2 0 . 3 5 0 . 33 23 . 8 25 n.d. 2.4 n.d. 0.5 •. B. E. Zlf5 6 25 1 40 305 2 45. 220 365. .a. 1 8? 3 50 1 37 300 4:.. 5. 15 72 � 2 1 00 21 57 < 3 90 1 .5 450 710 2380. -. 302 -. 8. -. 58 4: 50 1 35 2 42. -. -. -. -. -. 5. <. -. 57. 70. 10. 4 50. 1 300 2700. -. 450. 1 33 8. 2500. - Th i s w o rk . - D i r e c t :':l r c ing w i th h i gh d i sp e r s i o n i n s trum e n t ( TZNN/�NT and FELLO';� s , 1 967 ) . C R e c ommended v a l u e s for G- 1 and W- 1 ( FL.SIS CHER , 1 96 9 ) . D - N e u t r o n a c t i v :>. t i on ( }b S K I N and GEHL , 1 96 3 ) . E - M e d i an valu e s f o r CArlS s y en i t e ( S INE ET tL , 1 96 9 ) . n . d . - N o t d e t e rm i n e d . fl. B. -. I. Crti.S S y�ni t c. W-1. G- 1. Element.

(52) @ E. 0. 0. c 0. ... nJ >. ... (J. <C. @. c 0. """. ... ::I Q) z. D. G -1. 0. W-1. 10. S p e c t rogra phic Fig .. I. -. B. pp m. Neutron activation data from HASKIN and GEHL as a function of s pectrographic data from the author for G - 1 and W - 1 .. 1 00.

(53) 1 0 00. E. Q. Q.. @. .... 0 .r:. ::J. ..... <C. 0. 10. 1 &-----�--�-L-L��----�--L-��--L---� 100 1 10 1 0 00. T. Fig ,. I. -. 9. &. F.. ppm. Data from the author as a function of spectrographic data from TENNANT and FELLOWS for CAAS Syenite ..

(54) 30 . Tf,BL.S. I - 8. Rare Ear th �bundan c e R 3 t i o s f o r G- 1 , W- 1 �nd Cl,, .S S y e n i t e . C-�.1 1 Data N o rmal i s e d to L a = 1 . 00 by w 0 i ght ) . Rare Ear th E l e m e n t. S y en i t e N.E.C. T . &F .. B. La. 1 . 00. 1 . 00. 1 . 00. 1 . 00. Ce. 1 . 58. 1 . 84. 2 . 46. 2 . 73. Pr. 0 . 20. . 0 . 72. 0 . 55. 0 . 35. Nd. 0 . 62. 1 . 57. 1 . 17. 1 . 47. Pm. h. f,. -. -. -. -. Sm. 0.10. 0 . 025. 0 . 96. 0 . 36. Eu. 0 . 0094. 0 . 073. 0 . 029. 0. 10. Gd. 0 . 057. 0 . 33. 0 . 1 67. 0 . 39. Tb. 0 . 0030. 0 . 087. 0 . 1 74. 0 . 06. Dy Ho. 0 . 01 8. 0 . 45. 0 . 46. 0 . 30. 0 . 0034. 0 . 092. 0 . 0067. 0 . 081. Er. Tm. 0 . 0090. 0 . 25. 0. 1 4. 0. 1 8. 0 . 00 1 6. 0 . 01 3. 0 . 01 6. 0 . 023. Yb. 0 . 0035. 0 . 38. 0 . 1 83. 0.13. Lu. o . ooo8. 0 .- 0055. 0 . 03 1. 0 . 02 1. Average o f G- 1 ( HASKIN and - kverage A c i d i c R o ck p a t t e rn . Gehl , 1 963 ) and K i rovograd gran i t e ( G,:,VRILOVl• and TUR1-\ NSKJ\YJ. , 1 958 ) .. B - hverage b as i c r o ck p a t t e rn . Average o f W- 1 ( HASKIN and GEHL , 1 963 ) , and K i lau e a- i ki ( S C HM I TT ET AL 1 963a ) ..

(55) 31 .. appr o x i m a t e t o that o f �n average bas i c ro c k .. A. p l o t o f abundanc e. r a t i o ag� i n s t atom i c numb e r for the average gran i t e r o c k , av e r ag e b as i c ro c k a n d sy� � i t e fur t h e r c on f i rm e d t h i s . To h e lp evaluat e t h e relat i v e m er i t o f t h e valu e o f t h e s e d i s c ordant e l ement s , a s shown i n F i g . I - 9 , t h e abundan c e ra t i o s o f t h e rar e ear ths i n the av erage b as i c r o c k and the r e s u l t s o b t a i n e d for the s y � i t e i n t h i s w o rk , t o g e t h e r w i th tho s e v a l u e s o b t ai n e d b y T e nnan t a n d F e l l o w s , � e r e p l o t t e d agains t atomi c numb e r nnd are shown i n F i g .. I- 1 0 .. From thi s i t i s c l e arly s e e n. t h a t t h e e l em en t s s �m �r i um , h o l m i um a n d l u t e c ium do no t l i e as c l o s e to the curve of t h e average b a9 i c r o c k as do t h e o th e r rar e e a r t h e l em e n t s .. I f i t i s assumed t h a t t h e rare ear th abundanc e. r a t i o p a t t e rn i s c o ns i s t en t for al l m e m b er e l em ents, then the val u e f o r t h e d i s c ordan t c l ement c l o s er t o t h e c ur v e o f t h e average b as i c rock i s the value w hi c h is likely t o b e m o r e c o rr e c t .. If,. as i s t h e c a s e o f samar i um , b o t h t h e values l i e far from th e average b as i c r o c k curve , and are w i d e ly d i f fe r en t , t h e n i t i s l ik e l y t h a t b o th are i n c o rr e c t .. H o w e v e r , i f t h i s h ap p e ns , t h e. e s t im a t e d val u e can b e ob tai ned a n d i s i n t h i s c as e appr o x i m at e l y O n t h i s b as i s i t i s d o c i d e d that t h e author ' s value for. 3 7 ppm .. h o l m i u m ( 2 1 ppm ) is m o r e l ik e l y t o be c o rr e c t than t h a t o f T e nnant and F e l lows ( 2 ppm ) w h e reas t h e i r value for y t t e r b i u m ( 57 ppm ) is b e t t e r ( 90 ppm ) .. I t i s a l s o p o s s i b l e that t h e author ' s. value for l u t e c ium ( 1 . 5 ppm ) i s t o o l o w ; a value o f 3 ppm i s m o r e c o ns i s t e n t wi th t h e average b as i c ro c k c u rv e . It. i s c o n c l u d e d that the r e s u l t s i n Tabl e I - 6 and Tabl e I - 7. hav e d em o ns t r a t e d t h e fe a s i b i l i ty o f u s i ng. �. l a rge quar t z- op t i c s. ( m e dium d i sp e rs i on ) s p 1 • c t ro graph for the d e t e rm i na t i o n o � tiho r i um ,.

(56) w- 1 T. •. •. -o-; - -o- - .. &. F. A ut hor. 1 ·00. � R ,, II I I r ' I I. 0 ..... f '. ' ' ' ' ' ' ' ' '. CO a: CU O · l O 0 r: CO "C r: :::J .Q <. ' ' r ' ' I. I I I I I. '�. I I. 0·01 I. 6 La. Ce. Fig , I. Pr. -. 10. Nd. Pm. Sm. Eu. Gd. Tb. Dy. Ho. · Er. Tm. Yb. Rare earth distribution for an average basic rock and CAAS Syen ite .. Lu.

(57) 32 . y t t r i um and t h e r a r e ear ths p r o v i d e d that an i n i t i a l s eparat i on i s p r ev i ously carr i e d out ..

(58) 33. ANALYTICAL (a). METHODS. FOR. URAN I UM. Spec trogr�phi c Pro c edure for Macro �moun t s o f Ura n i um. The uranium s p e c trum i s e x trem 0ly c ompl e x , and b e c ause no l i n e s show h i gh tran s i t i on probab i l i t i e s the em i t te d radi u t i on i s d i s s i p a t e d nmong wnny l i nes .. As. a. res u l t , the s ens i t i v i ty i s low .. Al s o , w h e n pres e n t i n h i gh c onc e n tra t i o ns , uranium em i ts an i n t ense c on t i nuous b a c kground rad i a t i o n whi c h i n t erfer e s w i th i t s el f and o ther e l em e n t s .. B e c au s e of the s e p ro p er t i e s uranium is. a. difficult. e leme n t t o analys e spec t ro gr:tp h i c al ly . Uranium was analys e d under t h e s am e spec t ro grap h i c c o ndi t i o ns es t ab l i s hed for t h e analys i s o f thorium , y t trium and rare c�rths .. H ow ever , the l i m i t of det e c ti o n was only 0 . 8% uran i um ,. r e n d eri ng the techn i qu e sui t ab l e only for t h e analys i s o f m i neral s . F i g . I - 1 1 shows the work i n g curve ob t a i ned . (b). S o l u t i o n Fl uori m e t ry. S o l u t i on fluori m e try was i nv e s t i ga t e d ns i t i s w e l l known that t h i s t o c hn i qu e i s c o n s i d erably less s ens i t i v e than th8 extremely- s e ns i t i v e fus i o n- bead technique and , as be. a. a. res u l t , m igh t. s ui table m e tho d t o analyse for urcnium i n t h e i n termed i ate. c · l n c entra t i o n range bet w e e n that o f fus i o n- bead analys i s and s p e c trograp h i c analys i s .. S ILL and PETERSON ( 1 947 ) reported the. fluore s c e n c e of uranium in orthophosphori c a c i d and used t h i s property t o det erm i ne urani u m v i sual l y .. A s t h i s appeared to be. a p o s s i b l e method for analys i ng uranium in an i nt ermediate c on. c e n t ra t i on rQnge , the f o l l o w i ng i nves t i ga t i o n w as c arried ou t . A u r a n i u m s t andard ( 1 0 ppm ) was prepared i n s o lu t i ons o f. 5% , 1 0% , 20% , 50% , , 75 % and 1 00% phosphori c a c i d resp e c t i vely and the f lu o res cence measured w i th. a. fluorimeter .. The resu l t s are.

(59) 10. 10. % F ig . I : -. 11. u. Spectrograph ic working curve for uranium ..

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