Ash and Soil Conditioning Using Exothermic Metallic Compositions
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Ash and Soil Conditioning Using Exothermic Metallic Compositions O.K. Karlina, G.A. Varlackova, M.I. Ojovan, V.M. Tivansky, V.L.Klimov, G.Yu. Pavlova and S.A. Dmitriev Moscow Scientific and Industrial Association “Radon”, 2/14, The 7-th Rostovsky Lane, Moscow, 119121, RUSSIA, Email: [email protected] ABSTRACT A thermochemical approach to conditioning ash residue that involves the use of exothermic metallic compositions (EMC) has been previously reported. EMC intermixed with ash residue at the appropriate ratios can sustain a glass forming reaction wave that produces monolith glasslike blocks. Herein, the thermochemical conditioning process is extended for conditioning contaminated clay soils. The results are reported for a study of the conditioning process and product materials to determine the optimal processing parameters and to characterize the product materials. INTRODUCTION The ash residue obtained after solid radioactive waste incineration is to be conditioned prior to transportation and disposal in order to avoid possible release of radionuclides into the environment. Usually, contaminated clay soils have radionuclides strongly fixed to the clay particles. This makes cleaning (washing) the soil a complex task. This waste must also be conditioned to produce a waste form suitable for safe transportation and storage. Another type of waste that also requires conditioning before disposal is produced by water treatment facilities in the form of spent inorganic sorbents. The thermochemical processing of such wastes (ash, clay soil, and inorganic sorbents) is a possible route for ensuring safe conditioning. The thermochemical conditioning process can be divided into three phases: 1. Preparation of EMC and its intermixing with waste material (ash residue, clay soil, inorganic sorbent). 2. Initiation of self-sustaining heat-liberating reaction wave in the mixture. 3. Quenching (cooling) of the monolithic glass-like block obtained. The process is carried out directly in a transport/disposal container. Since reduction of the initial mixture volume occurs (to approximately 1/3 of the initial volume) the conditioning process is repeated a few times in each container. The EMC is a specialized composition of oxidizers and reductants. The process is based on oxidation-reduction reactions in the EMC and radioactive waste mixture that result in significant heat emission that melts the radioactive waste and forms a glass-like material without requiring an external power supply.
Earlier [1-3], we identified optimal EMC compositions for conditioning of simulated and real ash residues from radioactive waste incineration. The ash residue composition is represented mainly by glass-forming components providing glass-like phase formation during the solid-liquid-phase reaction. To condition clay soil contaminated by radionuclides and containing sand and metallic inclusions, it was necessary to determine the appropriate EMC (heat base) composition and heat base/waste ratio in order to provide the required mixture melt and form a stable glas
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