Abstract: Methods for waste treatment and compositions of stabilized waste elements are provided, typically for the disposal of arsenical wastes. Arsenic trioxide waste produced as a by-product of metal extraction is slurried in water for from 6 to 24 hours with finely divided quicklime to produce nonvolatile calcium arsenate (III). An excess of CaO stoichiometry with As is used to consume secondary waste species such as sulphate, silicate and iron oxides. The precipitated arsenate is oven dried at 120.degree. C. and then calcined in air between 15 minutes to several hours at 1000.degree. C. to 500.degree. C. respectively to oxidize arsenate (III) to arsenate (V) as Ca.sub.5 (AsO.sub.4).sub.3 (OH) (an apatite) as the major arsenic immobilization phase, with minor arsenic incorporated in Ca.sub.3 (AsO.sub.4).sub.2. Calcium sulphate anhydrate (sulphate immobilization) and calcium iron oxide (iron immobilization) are also produced.

Abstract: The present invention is directed to the art of treating waste using laser technology. Industrial and toxic waste materials are irradiated with a laser inside a reactor chamber such that they are heated to high temperatures. Organic compounds are thermally destroyed and chemical bonds are broken. Cool oxygen is pumped into the reactor to provide a refractory protective shield. Silica is added into the vessel at the high temperatures and encapsulates any heavy metals into its crystal matrix. The resulting solidified product may have a hardness of at least 8 on the Knoops scale of hardness and may be used as tooling, road material, oven lining, building materials and the like.

Abstract: This invention provides a process wherein hazardous or radioactive wastes in the form of liquids, slurries, or finely divided solids are mixed with finely divided glassformers (silica, alumina, soda, etc.) and injected directly into the plume of a non-transferred arc plasma torch. The extremely high temperatures and heat transfer rates makes it possible to convert the waste-glassformer mixture into a fully vitrified molten glass product in a matter of milliseconds. The molten product may then be collected in a crucible for casting into final wasteform geometry, quenching in water, or further holding time to improve homogeneity and eliminate bubbles.

Abstract: The specification discloses a process for stabilizing radionuclides extracted during the upgrading of minerals. The process comprises forming a composition of a radionuclide and a component and roasting the composition so that the component forms a crystalline phase having a structure that binds the radionuclides. Suitable components include a compound of a lanthanide and/or phosphorus and zirconia. Zirconia in its cubic form is useful in stabilizing uranium and thorium.

Abstract: An apparatus and method for treating materials that present disposal problems is provided. The treatment takes place within an aqueous stream and in an oxygen-deficient multiple zone system, and results in the thermal decomposition and/or separation of components within the treated material. The apparatus and method of this invention may be used for the treatment of non-hazardous and hazardous waste, including organic and inorganic compounds, radioactive materials, toxic compounds, binary chemicals (such as nerve gas) and heavy metals, prior to disposal.

Abstract: A method for the processing of solid organic sulfur-containing waste, in particular ion exchange media, from nuclear facilities, which method comprises that in a first step a) the waste is subjected to pyrolysis at the most at 700.degree. C. in a step b) the gas resulting from step a) is subjected to pyrolysis, in an optional step c) the gas resulting from step b) is exposed to a reductant bed, and in a step d) the gas from step b) or alternatively step c) is exposed to a bed of sulphide-forming metal to form metal sulphides and easily manageable harmless gases. Apparatus for carrying out the method comprises A) a pyrolysis reactor for the solid waste, B) a pyrolysis reactor for the gas from A), C) optionally, a reductant bed, and D) a bed of sulfur-forming metal for the gas from B) or C).

Abstract: A processing system for radioactive waste is composed of an adjusting tank having a sampling port, a solidification processing system, and a package inspection apparatus, and a package, of which inventory per a package has been exactly grasped, is prepared by solidification of the waste with the processing system after determining radioactivity of the waste by measurement before the solidifying process.In accordance with the present invention, data on radioactivity before and after preparation of package of waste become clear, and management of each package at transportation and intermediate storage of the packages is facilitated.

Abstract: An adsorbent useful for the adsorption of radioactive nuclides which comprises fibrous active carbon having a specific surface area of 1,000 m.sup.2 /g or more and an equilibrium moisture regain of 10% or more at a relative humidity of 45%; and a process for the volume-reduction treatment of radioactive liquid waste which comprises subjecting radioactive liquid waste containing radioactive nuclides to an adsorption treatment using an adsorbent comprising fibrous active carbon having a specific surface area of 1,000 m.sup.2 /g or more, and subsequently subjecting the spent adsorbent to an incineration treatment at a temperature which is equal to or higher than the ignition point of the fibrous active carbon.

Abstract: A method of melting treatment of radioactive miscellaneous solid wastes containing therein an electrically conductive substance and other waste components. This method comprises charging the radioactive miscellaneous solid wastes into a cold crucible induction melting furnace provided with a high-frequency coil; supplying a high-frequency current to the high-frequency coil of the melting furnace to thereby heat and melt the electrically conductive substance, e.g. a metal, in the miscellaneous solid wastes; indirectly heating the other components in the miscellaneous solid wasted by utilizing the electrically conductive substance as a starting source of heating and melting; and placing the whole of the radioactive miscellaneous solid wastes into a molten state.

Abstract: A process for treating radioactive waste in the form of contaminated powdery ionic exchange resin to make it suitable for final storage by reducing its volume as much as possible, includes mechanically dewatering the ion exchange resin. The dewatered ion exchange resin is mixed with a calcium compound. The mixture is dried at temperatures of up to 120.degree. C. and preferably about 50.degree. C. to 60.degree. C., and at a pressure of from 120 to 200 hPa, until a residual moisture content of less than 10% of the mass of the mixture is reached. The dry mixture is thermally treated at a pressure below atmospheric pressure by heating up to a temperature of from at least 120.degree. C. to at most 190.degree. C. The ion exchange resin thereby loses its water absorption and swelling capability. Ion exchange resins treated in this manner are processed with cement or bitumen to form blocks that are suitable for final storage.

Abstract: Method for destroying radioactive graphite and silicon carbide in fuel elements containing small spheres of uranium oxide coated with silicon carbide in a graphite matrix, by treating the graphite fuel elements in a molten salt bath in the presence of air, the salt bath comprising molten sodium-based salts such as sodium carbonate and a small amount of sodium sulfate as catalyst, or calcium-based salts such as calcium chloride and a small amount of calcium sulfate as catalyst, while maintaining the salt bath in a temperature range of about 950.degree. to about 1,100.degree. C. As a further feature of the invention, large radioactive graphite fuel elements, e.g. of the above composition, can be processed to oxidize the graphite and silicon carbide, by introducing the fuel element into a reaction vessel having downwardly and inwardly sloping sides, the fuel element being of a size such that it is supported in the vessel at a point above the molten salt bath therein.

Abstract: A submergible torch for removing nitrate and/or nitrite ions from a waste solution containing nitrate and/or nitrite ions comprises: a torch tip, a fuel delivery mechanism, a fuel flow control mechanism, a catalyst, and a combustion chamber. The submergible torch is ignited to form a flame within the combustion chamber of the submergible torch. The torch is submerged in a waste solution containing nitrate and/or nitrite ions in such a manner that the flame is in contact with the waste solution and the catalyst and is maintained submerged for a period of time sufficient to decompose the nitrate and/or nitrite ions present in the waste solution.

Abstract: A microwave applicator for processing of radioactive waste slurry uses a waveguide network which splits an input microwave of TE.sub.10 rectangular mode to TE.sub.01 circular mode. A cylindrical body has four openings, each receiving 1/4 of the power input. The waveguide network includes a plurality of splitters to effect the 1/4 divisions of power.