The development of safe and ecologically clean systems for handling radioactive wastes predetermines the sustained stability of geoecocenology.The measures adopted in the nuclear power industry for improving the safety of nuclear power plants have produced conditions for developing nuclear power in the future. The Kola Peninsula lies in a territory of active use of atomic energy, which results in accumulation of liquid and solid radioactive wastes, requiring processing and utilization, in the Murmansk region. These problems can and must be effectively solved taking account of the specific nature of the region. The Kola region is rich in mineral resources and wastes from mining, which can serve as material for producing and obtaining cheap sorption-active and self-hardening compositions for storing radioactive substances.Experience in preparing and handling radioactive wastes at nuclear power plants and other industrial plants associated with radioactive substances has shown that the most promising methods of immobilization and storage of liquid wastes is sorption on a solid-state adsorbent, sealing of the spent adsorbents in concrete blocks followed by vitrification and storage in underground or underwater repositories [1][2][3][4][5]. The subsequent arrangement of the spent adsorbents, elimination of contact with the surrounding medium or storage, impose definite requirements on the adsorbents: the radionuelides must form with the adsorbent matrix insoluble stable compounds which guarantee that the adsorbents are radioehemically stable in the immobilization medium without secondary contamination; the technical products must be convenient for subsequent operations: it must be possible to produce parts and blocks and to ensure shielding from radionnclides contained in the blocks formed; the adsorbents must be cheap and the technology must be simple. In turn, stringent requirements are imposed on the solidifying compositions (binder materials), which in geological formations contain the spent adsorbents: stability of binders with respect to mineralizing solutions and brines in a wide range of pH and ell; resistance to disintegration; low micro-and mesoporosity; closeness of the chemical and mineral compositions to that of the surrounding rock; low coefficient of diffusion of ground-water components in the binder medium; ability to strengthen the structure of the binder as a result of interaction of its components with the components of the geological immobilization medium; and, radiation resistance of the mineral forms of the binder. These requirements can be met by synthesizing technological materials using the technology of solidifying mineral dispersions (SMD materials) based on polymineral alumosilicate raw material [6][7][8][9]. These materials are based on the concept of synthesis of coagulation-condensation solidification structures in highly concentrated mineral dispersions. A highly concentrated mineral dispersion is a multiphase system containing a dispersed phase and a dispersion medium, which can intera...
Procedures for the preparation and granulation of sorbents based on TiO(HPO 4 ) . nH 2 O from the products of processing of sphene concentrate were developed. The sorption and hydrodynamic characteristics of the sorbents were determined. Titanium(IV) phosphates are of a great interest as sorption materials. Depending on synthesis conditions they can have the composition TiO(OH) 2x (HPO 4 ) 1 !x . nH 2 O, TiO(HPO 4 ) . nH 2 O, or Ti(HPO 4 ) 2 . nH 2 O, with TiO(HPO 4 ) . nH 2 O being prepared more easily. Hydrated oxotitanium hydrophosphate can be produced both as a fine amorphous powder and as a granulated product. It was shown in numerous studies that this sorbent efficiently absorbs cations of radionuclides [138] and also of nonferrous metals and iron [9314] from very dilute aqueous solutions. This sorbent can be used for efficient decontamination of liquid radioactive wastes, which are aqueous solutions with a high content (the studies covered concentrations of up to 32 g l !1 ) of salts present in seawater [15317]. Known procedures for preparing granulated sorbents are complicated and expensive [7, 18]. The developed technology of processing sphene concentrate for the synthesis of titanium phosphate sorbent (see scheme) can use titanium sulfate process solutions containing, g l !1 : TiO 2 160 3340, H 2 SO 4 280 3570, CaO 1.6 35.6, F 4.4 37.7, Fe 2 O 3 1.737.4, SiO 2 <0.05, and TR 2 O 3 <0.20 (solution after sulfatization in the scheme); titanium3silica product (TSP) containing, wt %: TiO 2 48, SiO 2 37, CaO 0.56 33.00, Ln 2 O 3 <0.018, Fe 2 O 3 <0.64, Al 2 O 3 <0.25, F <2.2, and NO 3 ! 3.60; and hydrolytic sulfuric acid containing, g l !1 : TiO 2 12313.5, Fe 2 O 3 up to 7.4, and F 4.4 37.7.In this work we studied the conditions of the synthesis of powdery titanium-phosphate sorbents based on TiO(HPO 4 ) . nH 2 O from titanium-containing products obtained in processing of sphene concentrate using simple granulation procedures, and also the sorption and hydrodynamic characteristics of these sorbents.EXPERIMENTAL Titanium(IV) was precipitated from titanium sulfate process solutions by a stoichiometric amount of orthophosphoric acid according to the reaction TiOSO 4 + H 3 PO 4 + nH 2 O = TiO(H 2 PO 4 )(HSO 4 ) . nH 2 O.(1)The further washing with water yields the desired product:TiO(H 2 PO 4 )(HSO 4 ) . nH 2 O = TiO(HPO 4 ) . nH 2 O + H 2 SO 4 .(2)The product (sorbent 1) contains 453 46.7 wt % water, which corresponds to n = 6.60 + 0.25. A comparison with sorbents synthesized from Ti(IV) sulfate solutions in the absence of fluoride ions shows that their presence in the titanium sulfate solution had no effect on the composition and properties of the product, because fluoride ions remained in the highly acidic mother liquor.
Recovery of thorium(IV) and radium(II) by precipitation methods in the chloride technology of perovskite processing was studied.
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