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Rapid determination of thorium in ores
VOL.
II.
11 (1954)
RAPID DE-I3’:RMINATION OF ‘I’l-IORIUM IN OIY
‘l’i~c clc:tctmiil:Ltion of thorium in minerals and arcs as ioclatc by I~OtiLSSiunl ioclatcl or by ioclatc-osalic :tcicl mixture 2 fails when it is prcscnt in tract amounts owing to intarfcrcncc with sulphuric acid, and the solubility losses in high nitric acicl concentration. For trace cstimxtion of thorium, Fnraraur nNI> L~AIIX~~ILD~ IKLVC used ;L lx-occclurc whicll is csscntially tlic chemical concentration of tliorium followccl by its cstimxtion (a) ncl~hclomctricnlly as ioclatc for quantities Icss than r mg of thorium (11) l~liotomctricnlly with pararsonic acid or (c) gravimetrically as osidc if more tlinn I: mg of thorium is indicated. lTl~rre~- AxI) Fos-r~rz~, aftcar obtaining the iurlatc in pure form, cstimntccl thorium indirectly by reduction of the ioclxtc wit11 lly~~o~~hospl~orous acicl in acid mcclium followed by photometric estimation of iodine cstrxtccl in carbon tctrachloridc. Ioclomctric titration h:~s ;~lso been rccon~xncnclccl. Tlic above methods use rnthcr large amounts of ore (about 5 g for 0.04 per cent.. thorium is rccommcndcd) micl in the cast of minerals like ilmcnitc, columbitctnntnlitc and samnrskitc they can bc usccl only after considcrablc time has lxen spout in opening up tlic mineral. Further, the use of mcrcurous nitrate as a carrier for thorium fluoriclc, andits subscqucnt volxtilization at the controllccl tcmpcrnturc, is not ii simple rnaniln~lation. The csscntkil features of the mctliocl now propsccl arc: (a) opening of the niincral with socli~lni pcrosidc (b) precipitation of tllorium as pliosphatc along wit11 zirconium or titanium, without prior removal of silica (c) treatment of the prccipitatc with llydrofluoric acid to rcmovc silica by volatilization, to form soluble fluoriclcs with intcrfcring clcmcnts and to scxvcngc thorium as fluoriclc using lantlianum as carrier (cl) prccipitatioti of thorium ah iodatc in potassium iodatcoxalic acid misturc ancl (c) its cstim;~tion by titrating against thiosulphntc, the ioclinc libcratcd in acid solution.
‘I’hc proccclurc as outlinccl above was first triccl on pure thorium aiicl tiioriumzirconium mixtures ill or&r to establish the optimum conclitions ns rcgnrcls volumes nncl concentration of rcngcnts.
licfc~Y?,zcc.~p. 32s
I. A I-gram sample is cautiously fused in a nickel crucible with 5-6 g of sodium pcroxidc:, the mass being lccpt in a liquid state for about To minutes. ‘I’ilc crucible is coolccl and transferred to a 250-ml bcnker. About 100 ml of cold water is nddcd and the melt is disintcgratcd. ‘l’hc crucible is rcmovecl and rinsed, first with water and then with llydrochloric acid (I :I) ant1 the rinses arc* acldccl to the solution. 2. The solution is nct~tralizcd with hydrochloric acid (I :I) and then TO ml of csccss hydrochloric acid (I :I) arc added. ‘I’lic contents of the lxnkcr arc* tligcstccl on the steam batll, mg of zirconium osiclc arc acldccl in tllc form of nitratca. (If titanium nncl zirconium arc alrcacly present in the sample, which can Ix> noticccl from the amount of prccipitatc bcforc addition of zirconium as carrier. it is not necessary to add zirconium.) ‘I’hc solution is wnrmccl to about (;)(I” (:. -1 g ot diammonium phosphate clissolvccl in about zo ml of water arc acldccl and the solution is dilutccl with water to 20~~ ml. ‘i’llc bcakcr is covered and its contents arc’ cligcstccl on the steam Ixltli for at least 2 hours. 3. ‘I’l~c solution is stirrccl and filtered on Wliutmari No. 5_co, zx cm pnl)cr. The prccipitatc is then wnslicd with 4 per cent. ammonium nitrate solution. 1. The lx-cxipitatc is then transfcrrccl to a ICO ml platinum dish. The palxr is Curnt in a platinum crucible and the ash nddccl to the dish. _ acid arc: aclclccl and cligcstccl on the: str%arn Ixltli, wllilc 3. 20 ml of liyclrofluoric is eval)oratccl until abouI S In1 stirring with a platinum rod, and the solution remain. x0 nil of liydrofluoric XCiCl arc again adclccl nncl tlic solution is rc-cvnporatcd to about S ml and then clilutcd with 30 ml of water. 6. Tlic solution is warmccl on tlic steam bat11 and x0 mg of lantlinnum osiclc. in tile form of nitrate arc :&lccl. The solution is stirred with a platinum rod and allowed to stand overnight at room tcmpcraturc. 7. Tile solution is filtered on ;t \Vhatm:u~ No. .I(), q cm filter l)apcr in a hard ‘i’lic lxccipitatc is wasliccl twice with I0 to rg ml of rubber or plastic funnel. ‘I’llc lW2cipitntc is then wnsllcd twice 5 per cent. liyclrofluoric acicl wash solution. with water. S. The l)apcr together with the prccipitatc is transfcrrcd back to the dish and carefully hcatcd so that the product chars but dots not ignite. \Vllcn fumes arc’ no longer cvolvcd the contents arc hcatccl at ~00~ C until carbon is burnt off. 9. The rcsiduc in the clish is carefully wcttcd with a few drops of water. 0.5 ml of acicl arc carefully added and the sulphuric acid and one drop of hydrofluoric dish is hcatcd on the hot plate for about 25 minutes until dry. ‘1‘hcn the dish is heated over a low l3unscn flame below 450” C until no more fumes appear. 15 ml of concentrated nitric acid are added to the dish ancl the solution IO. is evaporated to dryness on water bath. This is rcpcatccl two or three times, stirring with a glass rod, until all the thorium is in solution. illIt
Refcr*emes
p.
3aS
10
::zG
31.
?.I. ‘I’II,I.Lr, \-. -1.
A.1 II.\VAI,S3
VOL.
11
(1951)
II. liinally 2 ml of nitric acid (x:x) arc nddccl and the solution is transferred to :L 50 ml lxnlccr by means of ELjet of water and the dish “hobbicd” thoroughly. 1; ml of potassium ioclatc (rg per cent. in 1 :I: nitric acid) and 0.5 ml of osalic acid (To lwr cent.) arc ad&xl ancl the volume of solution is mndc to 25 ml. Filter paper
s.
Mincrnl
No.
oxide
tx1lccn
XldCCl
mg
.-_ A
J lrncllilc
---
llmenitc
Ilmcnitc proccsscrl to free it from radioactive mincrrds; Rrtdiometric assay; slightly less than sample A
0.3
O.lJ 0.9 1 .‘L
c
-
*Value by usual iodnlc roceclurc. Mineral not Fully annlysccl but contained 0.11 lxx cent. thoria and ;i littlc urxnium o.xicIc
-__
0.5
-
I G.o*
_-0,
- __ 0.W 1 .OtJ
2
V.,{
I=
SyuChctic contninitlg nium
mistrlrc zirco0.2 0. ‘I 0 ,s
0 .2 0 . _I
0.s
“. 5 0.5 ._ _._. _
-.-_ -.--._-___ . __._.__.___._____
llmcnitc obtained after magnrztic scparatiou 01 monnzitc. lkxlionictrlc assay: 0.2 per cent. 0E monnzite sand
‘I.3 0.b
1)
f01111d
.-_ ___mg ._ ..-~----
_-.-..
0.5 0 *5
“Vnluc by usunl xoilatc proccclurc. Mincxxl high in (Cb+Ta),O,, Ti0,,U,08 and rare earths; thorin 1.G per cent. 7,“;“s per cent. (CZ.b+-Tx.),O, .. c rr cat. !iO, with ittle uramum oxiclc and rare carth5
Containing %rO,
10 mg
of
Containing 1 g SnCl,,:!I-I,O and 0.5 mg ‘1’110, ..-- -- __..---.- --.- .----- - ---._. --
pulp is added to the solution and the solution is cooled in ice cold w,ltcr for about half an hour. 12. The supcmatant liquid is dccnntcd through a Whatman No. 43, L{ cm paper and finally the precipitate is transferred to the paper using a fine jet of 7G per cent. ice cold alcohol. (So ml of 95 per cent alcohol diluted with distilled water to xoo ml and cooled in ice colcl water.) The paper is washed three times with the alcohol solution. Total washings should not cxcccd 25 ml. The prccipitatc, along with the filter paper, is transferred to the bcakcr and trcatcd with z ml of sulphuric acid (I :I). This brings acid into contact with all parts of paper. After about five minutes 20 ml of water arc added and tllc solution is stirred until a fine pulp is formed. 5 ml of potassium iodide (IO per cent.) arc adclcd and the iodine libcratcd is titrated against o.o-~N sodium thiosulphutc, using starch solution as indicator. I ml of o.vxN thiosulpllatc is ccluivalcnt to 0.11 mg of thorium oxide. A number of complex minerals like ilmenitc, sam;lrskitc and columbitc-tantalitc have been analyscd by the same common prxcclurc as clcscribcd above and the results obtainccl on a I g sample arc given in Table I also along with the results obtained on a few synthetic misturcs. In samples A, 13, D and E it was not found ncccssary to add zirconium nitrate as ;L carrier. The volume of the prccipitatc obtaincci, though large, clid not offer any difficulties in subscqucnt operation.
Very complex minerals like ilmenitc, colunlbitc-tantalitc etc. llavc been analysed with great care within a short period of two working days. I\‘ith I g sample it is possible to estimate up to 0.01 per cent. thorium with a rcasonablc accuracy of 5 per cent. For still lower pcrccntages of thorium it would not bc difficult to apply the method with a larger amount of sample, i.c., 3 g, while for minerals which are of a simpler nature some of the steps in the rccomrncndcd proccdurc coulcl be omitted or suitably xnodificd. I-iighcr quantities of thorium up to 2.5 per cent. could also be analyscd titrimctrically by the procedure suggested in this paper.
A very rapid rncthocl for the estimation of tract amounts ol tho~lum up to 0.01 per cent. or thereabouts even in complcs niincrals like ilmenitc and columbitc-
tantalite has been described. Thorium is collected 111an acid solution with phosphates of zirconium and titanium without prior separation of silica, after decomposltlon of the mineral with sodium peroxide. Thorium is next collectad as fluoride wit11 lanthanum as a carrier, precipitated as thorium iodatc in potassium iodate-oxalic acid misturc and finally titrated aqamst 0.01 N sodium thiosulphntc. Accurate results arc obtained within a short time of two working clays. RcfeYc7lces p. 32s
Unc
n~~tl~oclc
t&s
rapidc
cst
proposGc
pottr
le dosage
de trxces
de thorium
jusqu’h
o.oL(%,, mhl0d~Lllsks IniLLeraiS COmplCxeS k!ls ~UCl'ilm~nitcCt1,2ColOmbite-tantalitC. Ix thorium cst cntrainG en solution acidc avec lcs phosphates de zirconium
et de apt&i cl6s:Lgrhgation tlu minerai par tttanc, snns sbparation pr&dsblc dc la silicc, Ic pcroxyclc clc socliunl. J_.e thorium cst ensuitc s6par6 commc fluorure, en pr&znce de lw~tlt:~tte, prfkipit.6 c0tnme ioclatc clc thorium par le m6langc ioclnte clc potxslc thiosulfatc dc sodium 0.01 .V. o.xalique ct fitialcmcnt titri: par hium - iicidc J)cs dsultats prdcis botit obtenu9 rapirlcmcnt: en clcux jours environ. %USAMMENFASSUNG
1% wtrtl einc schr w2ltt~cllc Mcthoclc vorgcschlxgcn fur die l3cstimtiiuttg van ‘L’hortitnt his zu 0 or’%, sclbst in Icotnplcscn Miticralicti wit in ilmcnit uticl in Colutnbit-‘J’xntnlit. Uns ‘L’ltorium wircl nach ctttcm Aufschluss mit Natriumperoxytl, LLI uncl Tit:~tiphosph:~t, ohne vorwurcm Milieu in 1Asung gcbrxcht mit Zirlconlumhcrigc Abtrcnnung clcs Stlicitttns. Dann wircl dns Thorium als I’luoritl abgetrcnnt, tn Gcgcnw;Lrt von Lantltxn ~1s ‘Lhortutnioclat gef;illt mit clctn Gcmisch JCaliuntjocl;~tOsalsiittrc, 1tnc1 tntt Nntriumthiosulf;tt O.OI A/ tttrtcrt. Matt et-halt auf clicse Wctsc sclincll Kctlxuc 1Icsttltal.c: ungcfiilir in zwci ‘I’agcn.
R. M.
J. &h~Etc IM. TILLU
1;‘.s. liRLMALllI
~~~mlyticnl
AXI:, ikl. SPI~'I'.~~I<, Chctrt. %tfi , 3~ (1910) 30tJ. V. 1’. RTIIAVALI:, A HUl. Clrz.rrr. Ada, 1 1 (1qs.t) 62. A 2507 June x9.15, C. J. AND J. C. ~'-~~RcllItr>, Report
AN11
Clremistvy
o/ the Mn~tlrnlln~t
Pvojecl,
New
Sorlc,
McGraw-I-It11
Rcccivccl
April
l
rutlt,
I 95 1
II.
11 (1954)
RAPID DE-I3’:RMINATION OF ‘I’l-IORIUM IN OI
‘l’i~c clc:tctmiil:Ltion of thorium in minerals and arcs as ioclatc by I~OtiLSSiunl ioclatcl or by ioclatc-osalic :tcicl mixture 2 fails when it is prcscnt in tract amounts owing to intarfcrcncc with sulphuric acid, and the solubility losses in high nitric acicl concentration. For trace cstimxtion of thorium, Fnraraur nNI> L~AIIX~~ILD~ IKLVC used ;L lx-occclurc whicll is csscntially tlic chemical concentration of tliorium followccl by its cstimxtion (a) ncl~hclomctricnlly as ioclatc for quantities Icss than r mg of thorium (11) l~liotomctricnlly with pararsonic acid or (c) gravimetrically as osidc if more tlinn I: mg of thorium is indicated. lTl~rre~- AxI) Fos-r~rz~, aftcar obtaining the iurlatc in pure form, cstimntccl thorium indirectly by reduction of the ioclxtc wit11 lly~~o~~hospl~orous acicl in acid mcclium followed by photometric estimation of iodine cstrxtccl in carbon tctrachloridc. Ioclomctric titration h:~s ;~lso been rccon~xncnclccl. Tlic above methods use rnthcr large amounts of ore (about 5 g for 0.04 per cent.. thorium is rccommcndcd) micl in the cast of minerals like ilmcnitc, columbitctnntnlitc and samnrskitc they can bc usccl only after considcrablc time has lxen spout in opening up tlic mineral. Further, the use of mcrcurous nitrate as a carrier for thorium fluoriclc, andits subscqucnt volxtilization at the controllccl tcmpcrnturc, is not ii simple rnaniln~lation. The csscntkil features of the mctliocl now propsccl arc: (a) opening of the niincral with socli~lni pcrosidc (b) precipitation of tllorium as pliosphatc along wit11 zirconium or titanium, without prior removal of silica (c) treatment of the prccipitatc with llydrofluoric acid to rcmovc silica by volatilization, to form soluble fluoriclcs with intcrfcring clcmcnts and to scxvcngc thorium as fluoriclc using lantlianum as carrier (cl) prccipitatioti of thorium ah iodatc in potassium iodatcoxalic acid misturc ancl (c) its cstim;~tion by titrating against thiosulphntc, the ioclinc libcratcd in acid solution.
‘I’hc proccclurc as outlinccl above was first triccl on pure thorium aiicl tiioriumzirconium mixtures ill or&r to establish the optimum conclitions ns rcgnrcls volumes nncl concentration of rcngcnts.
licfc~Y?,zcc.~p. 32s
I. A I-gram sample is cautiously fused in a nickel crucible with 5-6 g of sodium pcroxidc:, the mass being lccpt in a liquid state for about To minutes. ‘I’ilc crucible is coolccl and transferred to a 250-ml bcnker. About 100 ml of cold water is nddcd and the melt is disintcgratcd. ‘l’hc crucible is rcmovecl and rinsed, first with water and then with llydrochloric acid (I :I) ant1 the rinses arc* acldccl to the solution. 2. The solution is nct~tralizcd with hydrochloric acid (I :I) and then TO ml of csccss hydrochloric acid (I :I) arc added. ‘I’lic contents of the lxnkcr arc* tligcstccl on the steam batll, mg of zirconium osiclc arc acldccl in tllc form of nitratca. (If titanium nncl zirconium arc alrcacly present in the sample, which can Ix> noticccl from the amount of prccipitatc bcforc addition of zirconium as carrier. it is not necessary to add zirconium.) ‘I’hc solution is wnrmccl to about (;)(I” (:. -1 g ot diammonium phosphate clissolvccl in about zo ml of water arc acldccl and the solution is dilutccl with water to 20~~ ml. ‘i’llc bcakcr is covered and its contents arc’ cligcstccl on the steam Ixltli for at least 2 hours. 3. ‘I’l~c solution is stirrccl and filtered on Wliutmari No. 5_co, zx cm pnl)cr. The prccipitatc is then wnslicd with 4 per cent. ammonium nitrate solution. 1. The lx-cxipitatc is then transfcrrccl to a ICO ml platinum dish. The palxr is Curnt in a platinum crucible and the ash nddccl to the dish. _ acid arc: aclclccl and cligcstccl on the: str%arn Ixltli, wllilc 3. 20 ml of liyclrofluoric is eval)oratccl until abouI S In1 stirring with a platinum rod, and the solution remain. x0 nil of liydrofluoric XCiCl arc again adclccl nncl tlic solution is rc-cvnporatcd to about S ml and then clilutcd with 30 ml of water. 6. Tlic solution is warmccl on tlic steam bat11 and x0 mg of lantlinnum osiclc. in tile form of nitrate arc :&lccl. The solution is stirred with a platinum rod and allowed to stand overnight at room tcmpcraturc. 7. Tile solution is filtered on ;t \Vhatm:u~ No. .I(), q cm filter l)apcr in a hard ‘i’lic lxccipitatc is wasliccl twice with I0 to rg ml of rubber or plastic funnel. ‘I’llc lW2cipitntc is then wnsllcd twice 5 per cent. liyclrofluoric acicl wash solution. with water. S. The l)apcr together with the prccipitatc is transfcrrcd back to the dish and carefully hcatcd so that the product chars but dots not ignite. \Vllcn fumes arc’ no longer cvolvcd the contents arc hcatccl at ~00~ C until carbon is burnt off. 9. The rcsiduc in the clish is carefully wcttcd with a few drops of water. 0.5 ml of acicl arc carefully added and the sulphuric acid and one drop of hydrofluoric dish is hcatcd on the hot plate for about 25 minutes until dry. ‘1‘hcn the dish is heated over a low l3unscn flame below 450” C until no more fumes appear. 15 ml of concentrated nitric acid are added to the dish ancl the solution IO. is evaporated to dryness on water bath. This is rcpcatccl two or three times, stirring with a glass rod, until all the thorium is in solution. illIt
Refcr*emes
p.
3aS
10
::zG
31.
?.I. ‘I’II,I.Lr, \-. -1.
A.1 II.\VAI,S3
VOL.
11
(1951)
II. liinally 2 ml of nitric acid (x:x) arc nddccl and the solution is transferred to :L 50 ml lxnlccr by means of ELjet of water and the dish “hobbicd” thoroughly. 1; ml of potassium ioclatc (rg per cent. in 1 :I: nitric acid) and 0.5 ml of osalic acid (To lwr cent.) arc ad&xl ancl the volume of solution is mndc to 25 ml. Filter paper
s.
Mincrnl
No.
oxide
tx1lccn
XldCCl
mg
.-_ A
J lrncllilc
---
llmenitc
Ilmcnitc proccsscrl to free it from radioactive mincrrds; Rrtdiometric assay; slightly less than sample A
0.3
O.lJ 0.9 1 .‘L
c
-
*Value by usual iodnlc roceclurc. Mineral not Fully annlysccl but contained 0.11 lxx cent. thoria and ;i littlc urxnium o.xicIc
-__
0.5
-
I G.o*
_-0,
- __ 0.W 1 .OtJ
2
V.,{
I=
SyuChctic contninitlg nium
mistrlrc zirco0.2 0. ‘I 0 ,s
0 .2 0 . _I
0.s
“. 5 0.5 ._ _._. _
-.-_ -.--._-___ . __._.__.___._____
llmcnitc obtained after magnrztic scparatiou 01 monnzitc. lkxlionictrlc assay: 0.2 per cent. 0E monnzite sand
‘I.3 0.b
1)
f01111d
.-_ ___mg ._ ..-~----
_-.-..
0.5 0 *5
“Vnluc by usunl xoilatc proccclurc. Mincxxl high in (Cb+Ta),O,, Ti0,,U,08 and rare earths; thorin 1.G per cent. 7,“;“s per cent. (CZ.b+-Tx.),O, .. c rr cat. !iO, with ittle uramum oxiclc and rare carth5
Containing %rO,
10 mg
of
Containing 1 g SnCl,,:!I-I,O and 0.5 mg ‘1’110, ..-- -- __..---.- --.- .----- - ---._. --
pulp is added to the solution and the solution is cooled in ice cold w,ltcr for about half an hour. 12. The supcmatant liquid is dccnntcd through a Whatman No. 43, L{ cm paper and finally the precipitate is transferred to the paper using a fine jet of 7G per cent. ice cold alcohol. (So ml of 95 per cent alcohol diluted with distilled water to xoo ml and cooled in ice colcl water.) The paper is washed three times with the alcohol solution. Total washings should not cxcccd 25 ml. The prccipitatc, along with the filter paper, is transferred to the bcakcr and trcatcd with z ml of sulphuric acid (I :I). This brings acid into contact with all parts of paper. After about five minutes 20 ml of water arc added and tllc solution is stirred until a fine pulp is formed. 5 ml of potassium iodide (IO per cent.) arc adclcd and the iodine libcratcd is titrated against o.o-~N sodium thiosulphutc, using starch solution as indicator. I ml of o.vxN thiosulpllatc is ccluivalcnt to 0.11 mg of thorium oxide. A number of complex minerals like ilmenitc, sam;lrskitc and columbitc-tantalitc have been analyscd by the same common prxcclurc as clcscribcd above and the results obtainccl on a I g sample arc given in Table I also along with the results obtained on a few synthetic misturcs. In samples A, 13, D and E it was not found ncccssary to add zirconium nitrate as ;L carrier. The volume of the prccipitatc obtaincci, though large, clid not offer any difficulties in subscqucnt operation.
Very complex minerals like ilmenitc, colunlbitc-tantalitc etc. llavc been analysed with great care within a short period of two working days. I\‘ith I g sample it is possible to estimate up to 0.01 per cent. thorium with a rcasonablc accuracy of 5 per cent. For still lower pcrccntages of thorium it would not bc difficult to apply the method with a larger amount of sample, i.c., 3 g, while for minerals which are of a simpler nature some of the steps in the rccomrncndcd proccdurc coulcl be omitted or suitably xnodificd. I-iighcr quantities of thorium up to 2.5 per cent. could also be analyscd titrimctrically by the procedure suggested in this paper.
A very rapid rncthocl for the estimation of tract amounts ol tho~lum up to 0.01 per cent. or thereabouts even in complcs niincrals like ilmenitc and columbitc-
tantalite has been described. Thorium is collected 111an acid solution with phosphates of zirconium and titanium without prior separation of silica, after decomposltlon of the mineral with sodium peroxide. Thorium is next collectad as fluoride wit11 lanthanum as a carrier, precipitated as thorium iodatc in potassium iodate-oxalic acid misturc and finally titrated aqamst 0.01 N sodium thiosulphntc. Accurate results arc obtained within a short time of two working clays. RcfeYc7lces p. 32s
Unc
n~~tl~oclc
t&s
rapidc
cst
proposGc
pottr
le dosage
de trxces
de thorium
jusqu’h
o.oL(%,, mhl0d~Lllsks IniLLeraiS COmplCxeS k!ls ~UCl'ilm~nitcCt1,2ColOmbite-tantalitC. Ix thorium cst cntrainG en solution acidc avec lcs phosphates de zirconium
et de apt&i cl6s:Lgrhgation tlu minerai par tttanc, snns sbparation pr&dsblc dc la silicc, Ic pcroxyclc clc socliunl. J_.e thorium cst ensuitc s6par6 commc fluorure, en pr&znce de lw~tlt:~tte, prfkipit.6 c0tnme ioclatc clc thorium par le m6langc ioclnte clc potxslc thiosulfatc dc sodium 0.01 .V. o.xalique ct fitialcmcnt titri: par hium - iicidc J)cs dsultats prdcis botit obtenu9 rapirlcmcnt: en clcux jours environ. %USAMMENFASSUNG
1% wtrtl einc schr w2ltt~cllc Mcthoclc vorgcschlxgcn fur die l3cstimtiiuttg van ‘L’hortitnt his zu 0 or’%, sclbst in Icotnplcscn Miticralicti wit in ilmcnit uticl in Colutnbit-‘J’xntnlit. Uns ‘L’ltorium wircl nach ctttcm Aufschluss mit Natriumperoxytl, LLI uncl Tit:~tiphosph:~t, ohne vorwurcm Milieu in 1Asung gcbrxcht mit Zirlconlumhcrigc Abtrcnnung clcs Stlicitttns. Dann wircl dns Thorium als I’luoritl abgetrcnnt, tn Gcgcnw;Lrt von Lantltxn ~1s ‘Lhortutnioclat gef;illt mit clctn Gcmisch JCaliuntjocl;~tOsalsiittrc, 1tnc1 tntt Nntriumthiosulf;tt O.OI A/ tttrtcrt. Matt et-halt auf clicse Wctsc sclincll Kctlxuc 1Icsttltal.c: ungcfiilir in zwci ‘I’agcn.
R. M.
J. &h~Etc IM. TILLU
1;‘.s. liRLMALllI
~~~mlyticnl
AXI:, ikl. SPI~'I'.~~I<, Chctrt. %tfi , 3~ (1910) 30tJ. V. 1’. RTIIAVALI:, A HUl. Clrz.rrr. Ada, 1 1 (1qs.t) 62. A 2507 June x9.15, C. J. AND J. C. ~'-~~RcllItr>, Report
AN11
Clremistvy
o/ the Mn~tlrnlln~t
Pvojecl,
New
Sorlc,
McGraw-I-It11
Rcccivccl
April
l
rutlt,
I 95 1