2013

Leaching of radioactive and rare-earth elements from pegmatite steenstrupine and from rocks of the Lovozero massif

Ermolaeva V.N., Kolesov G.M., Mikhailova A.V., Kogarko L.N.

GEOKHI RAS

Due to high contents of Th, U and REE alkaline rocks of Lovozero massif may be considered as a potential object for the leaching of the radioactive and rare elements.

In alkaline rocks of Lovozero massif we find new important form of concentration of Th, U и REE – it is minerals of steenstrupine-(Ce) – thorosteenstrupine series Na_0-5Ca_1-3(REE,Th)₆(Mn,Fe,Al,Ti)_4-5[Si₆O₁₈]₂[(Si,P)O₄]₆(OH,F,O)_X·nH₂O. They are widely spread also in pegmatite bodies of the massif, they contain up to 29.14 mass. % of Th and up to 2.56 mass. % of U (Chukanova et al., 2004). In this regard we make a number of experiences by leaching of  Th, U и REE from pegmatite steenstrupine and steenstrupine-containing magmatic rocks of the Lovozero massif by several reagents: 1N solutions of HCl, NaOH, Na₂CO₃, 2% solutions of (NH₄)₂C₂O₄ (ammonium oxalate) и C₁₀H₁₄O₈N₂Na₂·2H₂O (trilon B). After leaching solutions was analyzed by ICP MS method in the case of steenstrupine and NAA in the case of steenstrupine-containing rocks. Use for sorption concentration of components of solutions after leaching from steenstrupine-containing rocks polymeric hydrogels on the basis of the polyacrylamide was feature of our approach. This hydrogels are capable to hold large amounts of water (up to 104 sm² on 1 g of polymer) and the substances dissolved in it (Savvin et al., 2009).

Our experiments shown, that most degree of leaching both petrogenic and rare elements from the minerals of steenstrupine-(Ce) – thorosteenstrupine series is observed for HCl and trilon B. Results of leaching from the rocks show, that Th from lujavrite is leached most effective by HCl, (NH₄)C₂O₄ and C₁₀H₁₄O₈N₂Na₂·2H₂O solutions, U – Na(OH), and REE – HCl. For foyaite samples HCl, (NH₄)C₂O₄ and C₁₀H₁₄O₈N₂Na₂ solutions as a whole are most effective for radioactive and rare earth elements extraction. So we can conclude that the obtained data testify to efficiency of elements concentration on hydrogel and their INAA-determination.

Chukanova (Ermolaeva) V.N., Kogarko L.N., Williams Ch.T., Pekov I.V., Chukanov N.V. Compositional features and genesis of steenstrupine from igneous rocks
of the Lovozero alkaline massifs, Kola Peninsula // Geochemistry International. 2004. № 4. P. 295-308.

Savvin S.B., Kolesov G.M., Mikhailova A.V. Water systems: concentrating concentrating
and determine of the metals with using polymeric hydrogels and neytron-activation analyze // Water: chemistry and ecology. 2009. № 9. P. 37–40.