Classifications

• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
  • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
  • G21F9/28—Treating solids
  • G21F9/30—Processing
  • G21F9/301—Processing by fixation in stable solid media
  • G21F9/302—Processing by fixation in stable solid media in an inorganic matrix
  • G21F9/304—Cement or cement-like matrix
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/91—Use of waste materials as fillers for mortars or concrete

Definitions

• This invention relates to a method for the treatment of waste by encapsulation. More specifically, it is concerned with the encapsulation of waste products produced in the nuclear industry by treatment of the wastes with microfine inorganic filler materials.
• Encapsulation has proved to be an especially favoured method for the disposal of certain waste materials; specifically it provides a suitable means for the conversion of these materials into a stable and safe form, which allows for long-term storage and/or ultimate disposal.
• the technique can find particular application in the nuclear industry, where the highly toxic nature of the materials involved, and the extended timescales over which the toxicity is maintained, are the principal considerations when devising safe disposal methods.
• EP-A-412913 teaches the use of a Portland Cement based grout in the consolidation of concrete structures affected by fine cracks, providing a cost-effective means of infilling both superficial and deeper fissures and cavities in such structures, including such as buildings, bridges and dams.
• ZA-A-9209810 is concerned with a pumpable, spreadable grouting composition incorporating a cementitious and/or pozzolanic or equivalent material, and its application in sealing fissures and cracks, back-filling, providing mass fills in civil and mining works, or lining tunnels.
• hydraulic setting compositions comprising particles of Portland Cement together with fine particles of silica fume containing amorphous silica, which are the subject of EP-A-534385 and are used in the production of concrete, mortar or grout having improved fluidity
• GB-A-2187727 describes a rapid gelling, hydraulic cement composition which comprises an acrylic gelling agent, a fine filler and Portland Cement, this composition being thixotropic and finding particular application in the formation of bulk infills for underground mining, and in the filling of voids and cavities in construction or civil engineering.
• a composition which also is useful in general building and construction work, and as an insulating material comprises a particulate filler, cellulose fibres and a cementitious binder, and is disclosed in GB-A-2117753.
• EP-A-801124 Whilst the majority of these compositions of the prior art have a requirement for the addition of water, EP-A-801124 is concerned with a dry mixture, used for fine soil injection grout preparation, the mixture comprising fillers which do not react with water, cement and deflocculant; on addition of water, an agglomerate-free fine grout is formed, and this is easily injected into fine soil.
• a method for the encapsulation of fine particulate materials which comprises treating said materials with at least one microfine hydraulic inorganic filler.
• the microfine hydraulic inorganic filler comprises a cementitious material, preferably Portland Cement.
• One or more additional inorganic fillers may optionally be added to the cementitious material; suitable fillers include blast furnace slag, pulverised fuel ash, hydrated lime, finely divided silica, limestone flour and organic and inorganic fluidising agents.
• the filler is ground to a much smaller particle size than is normally used in the production of a grout.
• the filler has a maximum particle size of less than 10 ⁇ m.
• the microfine hydraulic inorganic filler is provided in the form of an aqueous composition for the treatment of the fine particulate materials; the water content of the composition is preferably in the region of 40-50% (w/w).
• the filler may be pumped under pressure through the materials in order to ensure that they become intimately encapsulated. In this way, the filler is able to fill the very small interstitial cavities in the waste, thereby achieving intimate encapsulation without the need to remove the materials from their container, with all the attendant disadvantages that would be associated with such a procedure.
• the method of the present invention may be distinguished over the prior art, since all the known methods involve the mixing of materials and filler in a container, whereas mixing of the filler into an aqueous composition occurs prior to treatment of the materials in the container in the present case.
• the intimate encapsulation which is a feature of the present method would not be achievable by using the methods of the prior art.
• a further advantage of the present method is that the container in which the fine particulate materials are held may be used as part of the waste packaging.
• the method of the present invention may be applied to the treatment of a wide range of fine particulate materials.
• the application of the method to the treatment of waste materials in general and, most particularly, waste materials which are encountered in the nuclear industry which, as previously discussed, provide particular areas of concern in their disposal.
• Such materials may be treated by this method in order to eliminate many of the practical handling difficulties, and potential contamination hazards, which would be associated with the need to remove the materials from their containers prior to treatment.
• a particular example of the application of the method in the field of nuclear technology involves the treatment of filters containing ion exchange resins.
• Said filters may typically be used for both liquids and gases and a particular application is in the removal of caesium from waste ponds.
• the used filters comprise cartridges of spent ion exchange resin and these may be successfully encapsulated using the technique according to the present invention.

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• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Processing Of Solid Wastes (AREA)
• Chemical Treatment Of Metals (AREA)
• Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
• Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)

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Citations (19)

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• 2001
  • 2001-12-21 GB GBGB0130593.7A patent/GB0130593D0/en not_active Ceased
• 2002
  • 2002-12-20 AU AU2002367212A patent/AU2002367212A1/en not_active Abandoned
  • 2002-12-20 US US10/499,283 patent/US20050131265A1/en not_active Abandoned
  • 2002-12-20 WO PCT/GB2002/005861 patent/WO2003056571A2/fr not_active Ceased
  • 2002-12-20 AT AT02805831T patent/ATE458253T1/de not_active IP Right Cessation
  • 2002-12-20 EP EP02805831A patent/EP1459326B1/fr not_active Expired - Lifetime
  • 2002-12-20 DE DE60235405T patent/DE60235405D1/de not_active Expired - Lifetime
• 2006
  • 2006-10-05 US US11/538,969 patent/US7445591B2/en not_active Expired - Fee Related

Patent Citations (19)

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