Geopolymer materials based on magnesia-iron slags for normalization and storage of radioactive wastes

Abstract

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...

An environmental evaluation of geopolymer based concrete production: reviewing current research trends

“…For example while magnesium iron slags (Zosin et al, 1998), ferronickel slags (Komnitsas et al, 2007) or tungsten mine waste mud (Pacheco-Torgal et al, 2007) are of little or no benefit in blended cement technology, they can be used successfully as geopolymeric binders. Slag based geopolymer concrete only requires small amount of sodium silicate and therefore has the lowest environmental impact.…”

Novel modification method for inorganic geopolymer by using water soluble organic polymers

“…Besides, it is also a ''Green Material'' for its low manufacturing energy consumption [12] and low waste gas emission [5]. Because of these prominent characteristics, geopolymer was considered as one of the potential candidates to solve the conflict of social development against environmental pollution [13] and have been widely used to partially take the places of conventional materials in the fields of fire resistance [14], nuclear wastes solidification [15], hazardous wastes disposal [16], binder [17], fast reparation [18], decoration [19], intelligent material [20] and construction [21].…”

Other Potential Applications for Alkali-Activated Materials

“…As in the case of Pb and Cr immobilisation, noted in section 12.5.2.1, partial replacement of BFS by zeolite or metakaolin has also been reported to decrease the leaching of Cs + and Sr 2+ from the hardened pastes [ 170 , 172 ], due to the specifi c adsorption properties of C-(A)-S-H and zeolite precursor-type phases. Alkali-activated binders derived from magnesiairon slags have also been developed in Russia for the treatment of wastes bearing radioactive Cs, Co and Ru, with apparent success in terms of physical property development and leaching performance [ 173 ].…”