PURIFICATION METHOD OF LITHIUM 1 lilPAUWELeS an d K. F. LAUER Çî'ljl·1«*, Joint Nuclear Research Center Geel Establishment - Belgium Central Bureau for Nuclear Measurements - CBNM m rth ·«·>·»· TJ ΪΓ tfl " ■ imp Γ|ί*Γ ¡fö'ffltl i »'rtrtpít Β 111 iWMVWjtK'1* i » *.ΗΙΗ i rt»1»*' ·1 fittili rwi : : ij iff-» lii LEGAL NOTICE »h>'<t m This document was prepared under the sponsorship of the Commission of the European Communities. Neither the Commission of the European Communities, its m contractors nor any person acting on their behalf : W- WSW S Make any warranty or representation, express or implied, with ι»: respect to the accuracy, completeness, or usefulness of the information contained in this document, or that the use of any information, apparatus, method, or process disclosed in this document may not infringe privately owned rights ; or Assume any liability with respect to the use of, or for damages resulting from the use of any information, apparatus, method or process disclosed in this document. illiiliïitt ..SMID«'liJTma»ÉiP! i \mm n >>:ύ ÙM fer ¡a i WhTvil'îτΊ!-filt» flKwkk »rûiUJI »¡¿rtlüUCUB·'!!·'LkS*í'·7a*»iPVTι w This report is on sale at the addresses listed on cover npage .4 the price of FF 4 BP MW ¡feii'lfâ EUR 4072 e THE DEVELOPMENT OP A PURIFICATION METHOD OF LITHIUM by J. PAUWELS and K.F. LAUER European Atomic Energy Community — EURATOM Joint Nuclear Research Center — Geel Establishment (Belgium) Central Bureau for Nuclear Measurements — CBNM Brussels, September 1968 — 22 Pages — 3 Figures — FB 40 A purification method of lithium on a cation-exchange resin in 1 M HCl was described. To allow the preparation of lithium containing Z. 50 ppm alkali and alkali-earth metals, a special purification of the ion-exchanger was needed. A method using batch operations with the tetra lithium salt of EDTA, with 30 % hydrochloric acid, and elution with 1 M hydrochloric acid was described. EUR 4072 e THE DEVELOPMENT OF A PURIFICATION METHOD OF LITHIUM by J. PAUWELS and K.F. LAUER European Atomic Energy Community — EURATOM Joint Nuclear Research Center — Geel Establishment (Belgium) Central Bureau for Nuclear Measurements — CBNM Brussels, September 1968 — 22 Pages — 3 Figures — FB 40 A purification method of lithium on a cation-exchange resin in 1 M HCl was described. To allow the preparation of lithium containing ^ 50 ppm alkali and alkali-earth metals, a special purification of the ion-exchanger was needed. A method using batch operations with the tetra lithium salt of EDTA, with 30 % hydrochloric acid, and elution with 1 M hydrochloric acid was described. EUR 4072 e THE DEVELOPMENT OF A PURIFICATION METHOD OF LITHIUM by J. PAUWELS and K.F. LAUER European Atomic Energy Community — EURATOM Joint Nuclear Research Center — Geel Establishment (Belgium) Central Bureau for Nuclear Measurements — CBNM Brussels, September 1968 — 22 Pages — 3 Figures — FB 40 A purification method of lithium on a cation-exchange resin in 1 M HCl was described. To allow the preparation of lithium containing Z. 50 ppm alkali and alkali-earth metals, a special purification of the ion-exchanger was needed. A method using batch operations with the tetra lithium salt of EDTA, with 30 % hydrochloric acid, and elution with 1 M hydrochloric acid was described. EUROPEAN ATOMIC ENERGY COMMUNITY - EURATOM THE DEVELOPMENT OF A PURIFICATION METHOD OF LITHIUM by J. PAUWELS and K. F. LAUER 1968 Joint Nuclear Research Center Geel Establishment - Belgium Central Bureau for Nuclear Measurements - CBNM SUMMARY A purification method of lithium on a cation-exchange resin in 1 M HCl was described. To allow the preparation of lithium containing ¿1 50 ppm alkali and alkali-earth metals, a special purification of the ion-exchanger was needed. A method using batch operations with the tetra lithium salt of EDTA, with 30 % hydrochloric acid, and elution with 1 M hydrochloric acid was described. KEYWORDS REFINING IMPURITIES SEPARATION PROCESSES LITHIUM ION EXCHANGE MATERIALS EDTA HYDROCHLORIC ACID - 3 Contents page 1. Introduction 1 2. Principle of the method 2 3. Experimental details of the method 2 3. 1. Elements of interest and their determination 2 3.2. Determination of distribution coefficiente 2 3.3. Determination of purification factors (PF) 4 3.4. Purification of AG 50W-XI6 5 4. Results and conclusion 7 References 9 5 - 1. Introduction In a previous report, four methods of determination of 0. 1 M lithium hydroxide solutions with a final accuracy of 0.02% were described . As these methods, which are not selec- ri 7 tive, have to be applied to Li and Li solutions for the pre­ paration of isotopie blends, and no chemically pure Li or 7 Li samples were available, a purification method of lithium was needed. The purity of the final lithium has to be such, that the resi­ dual impurities do not cause any hygroscopy that might dis­ turb gravimetry of the formed lithium salts, and that cor­ rections for systematic errors are practically negligible. Further, the lithium has to be in such a form that its trans­ formation into a pure 0. 1 M aqueous hydroxide solution is possible. L η The most important impurities found in enriched Li or Li samples were alkali- and alkali-earth metals (up to 0. 15% together). Different separations of lithium from these elements were reported earlier, but they were mostly limited to one or two elements, and few authors give indications about the absolute purity of the separated lithium fraction. Most of (2-6^ these methods are based on extraction , precipitation (7-12) , . (13-35) x , or ion exchange chromatography Nevertheless, the most recent of them all concern separa­ tions on cation exchange resins in the hydrogen form. An presencimportane t ostudf Dowey ofx th5e0 anbehavioud Duolitr e ofC 3th ei n alkalthe isyste metalm s HClin · v(35) H90 - CH OH was done by Nelson '. The described s paration method is based on this work. - 6 2. Principle of the Method In diluted hydrochloric acid the alkali metals are rather strongly absorbed by cation-exchanger s like Dowex 50, whereby lithium is the least absorbed one. From the values (35) of the distribution coefficients as determined by Nelson for Dowex-X4 it can be seen that quantitative separations must be possible. To obtain still higher selectivities it is useful to use a resin with a higher DVB-content ("X16"). The described purification was performed on AG 50W-X16 (50/100 mesh), a Dowex 50W-X16 specially purified for ana­ lytical purposes. Nevertheless, further purification of this resin was necessary. This was made by batch operations withE.D.T.A. in Li OH medium, concentrated hydrochloric acid and final elution with 1 M hydrochloric acid. 3. Experimental Details of the Method 3.1. Elements of interest and their determination 3.1.1. Lithium Lithium was localized in the eluate and determined for the calculation of the distribution coefficients by transformation into and calcination as sulfate. In the case of the Κ,-determinations 5 ml fractions containing 7 to 15 mg of lithium sulfate were analysed. Under these con­ ditions a precision of 1-2% can be obtained. 3.1.2. Sodium, potassium, beryllium, magnesium and calcium During the determination of distribution coefficients and purification factors, these elements were determined rela- tively by tracing them with Na, K, Be, " Mg and Ca. The first four isotopes were measured by integral γ -counting 45 with a Nal(Tl) Well-type scintillation counter, Ca by rela­ tive β -counting. During the separation test Li/Mg, mag­ nesium was determined photometrically with titan yellow. 3.1.3. Trace analysis in ion-exchangers and purified lithiums Ion-exchangers were calcined and purified lithiums dried as lithium chloride. The residues were analysed for metal­ lic impurities by the emission spectrographic service of the C.B.N.M. 3.2. Determination of distribution coefficients (Κ ,) Distribution coefficients for lithium, sodium, potassium, beryllium, magnesium and calcium were determined for com­ mercial grade Dowex50W-Xl6 by batch equilibration tests on 1-2 grams oven dried resin and 10 ml of hydrochloric acid. Κ ..-values were calculated from relative measurements of α identical fractions of blanks and samples using the formula: M -M ml Κ d M1 g in which: M. = the total amount of the ion t M, = the amount present in the liquid ml = the number of milliliters of hydrochloric acid. g= the number of grams of oven-dried resin. A summary of the obtained results is given in figure 1. Separation factors β = Κ, /Κ are summarized in figure 2. M Li From this figure it can be seen that an efficient separation (β > 2) can be expected between 0. 5 and 2 M hydrochloric acid. To avoid contamination of the separated lithium by trace im­ purities contained in the ion-exchanger, it is important that the Κj-values of the elements to be separated are large, but a too - 8 large K,-value for lithium leads to broadening of the lithium peak in the effluent. 1 M hydrochloric acid was chosen as eluant. The K,- and ß-values derived from figures 1 and 2 for this medium were summarized in Table I. 3. 3. Determination of purification factors (P. F. ) 3.3.1. Method of separation Separations were performed on 3 cm diameter quartz columns filled with a quantity of resin equivalent to 80 grams of oven- dried Dowex 50W-X16 ( «400 meq.). Before the separation begins the resin is washed with bidistilled water, until chloride ions are fully removed. On the other hand 0.5 g of lithium and 100 to 500 /Ug of a traced alkali- or alkali earth metal are absorbed on 16 gram oven- dried Dowex 50W-X16 («80 meq.) by mixing during 30 minutes.