WO2023187740A1 - Treatment process for ion exchange resins - Google Patents
Treatment process for ion exchange resins Download PDFInfo
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- WO2023187740A1 WO2023187740A1 PCT/IB2023/053257 IB2023053257W WO2023187740A1 WO 2023187740 A1 WO2023187740 A1 WO 2023187740A1 IB 2023053257 W IB2023053257 W IB 2023053257W WO 2023187740 A1 WO2023187740 A1 WO 2023187740A1
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- WO
- WIPO (PCT)
- Prior art keywords
- ion exchange
- exchange resins
- treatment process
- treatment
- sub
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims abstract description 66
- 230000008569 process Effects 0.000 title claims abstract description 62
- 239000003456 ion exchange resin Substances 0.000 title claims abstract description 50
- 229920003303 ion-exchange polymer Polymers 0.000 title claims abstract description 50
- 238000005056 compaction Methods 0.000 claims abstract description 19
- 229920000876 geopolymer Polymers 0.000 claims abstract description 17
- 238000002156 mixing Methods 0.000 claims abstract description 17
- 229910000323 aluminium silicate Inorganic materials 0.000 claims abstract description 16
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 22
- 238000007711 solidification Methods 0.000 claims description 16
- 230000008023 solidification Effects 0.000 claims description 16
- 239000002901 radioactive waste Substances 0.000 claims description 14
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 claims description 11
- 239000000463 material Substances 0.000 claims description 11
- 230000003750 conditioning effect Effects 0.000 claims description 10
- 239000010881 fly ash Substances 0.000 claims description 10
- 238000003801 milling Methods 0.000 claims description 8
- 238000002203 pretreatment Methods 0.000 claims description 8
- 238000001704 evaporation Methods 0.000 claims description 7
- 230000002285 radioactive effect Effects 0.000 claims description 6
- 239000004927 clay Substances 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 3
- 239000011347 resin Substances 0.000 description 44
- 229920005989 resin Polymers 0.000 description 44
- 239000011159 matrix material Substances 0.000 description 22
- 239000004568 cement Substances 0.000 description 13
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 12
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 8
- 239000000126 substance Substances 0.000 description 8
- 230000008961 swelling Effects 0.000 description 8
- 239000000243 solution Substances 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 235000011118 potassium hydroxide Nutrition 0.000 description 6
- 235000011121 sodium hydroxide Nutrition 0.000 description 6
- 239000011398 Portland cement Substances 0.000 description 5
- 239000012467 final product Substances 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 230000009467 reduction Effects 0.000 description 5
- 239000000377 silicon dioxide Substances 0.000 description 5
- 239000007787 solid Substances 0.000 description 5
- 239000002699 waste material Substances 0.000 description 5
- 239000000843 powder Substances 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 239000005995 Aluminium silicate Substances 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 230000009471 action Effects 0.000 description 3
- 230000004913 activation Effects 0.000 description 3
- 239000012670 alkaline solution Substances 0.000 description 3
- 235000012211 aluminium silicate Nutrition 0.000 description 3
- 239000011230 binding agent Substances 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 238000011038 discontinuous diafiltration by volume reduction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000008020 evaporation Effects 0.000 description 3
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000003113 alkalizing effect Effects 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 229910052796 boron Inorganic materials 0.000 description 2
- 239000000292 calcium oxide Substances 0.000 description 2
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 2
- 239000013043 chemical agent Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000001143 conditioned effect Effects 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 239000003822 epoxy resin Substances 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 238000010348 incorporation Methods 0.000 description 2
- 238000005342 ion exchange Methods 0.000 description 2
- 229910052622 kaolinite Inorganic materials 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000003204 osmotic effect Effects 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 229920000647 polyepoxide Polymers 0.000 description 2
- 239000012286 potassium permanganate Substances 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 229910021487 silica fume Inorganic materials 0.000 description 2
- 229910052814 silicon oxide Inorganic materials 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 229910021653 sulphate ion Inorganic materials 0.000 description 2
- 238000007738 vacuum evaporation Methods 0.000 description 2
- 230000003313 weakening effect Effects 0.000 description 2
- GUTLYIVDDKVIGB-OUBTZVSYSA-N Cobalt-60 Chemical compound [60Co] GUTLYIVDDKVIGB-OUBTZVSYSA-N 0.000 description 1
- 206010017076 Fracture Diseases 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- RYXPMWYHEBGTRV-UHFFFAOYSA-N Omeprazole sodium Chemical compound [Na+].N=1C2=CC(OC)=CC=C2[N-]C=1S(=O)CC1=NC=C(C)C(OC)=C1C RYXPMWYHEBGTRV-UHFFFAOYSA-N 0.000 description 1
- 229910007156 Si(OH)4 Inorganic materials 0.000 description 1
- 229910020489 SiO3 Inorganic materials 0.000 description 1
- -1 Silica ions Chemical class 0.000 description 1
- 208000013201 Stress fracture Diseases 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 239000012190 activator Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 239000002956 ash Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- 239000011083 cement mortar Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 239000004567 concrete Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 230000001066 destructive effect Effects 0.000 description 1
- HOOWDPSAHIOHCC-UHFFFAOYSA-N dialuminum tricalcium oxygen(2-) Chemical compound [O--].[O--].[O--].[O--].[O--].[O--].[Al+3].[Al+3].[Ca++].[Ca++].[Ca++] HOOWDPSAHIOHCC-UHFFFAOYSA-N 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 229910052571 earthenware Inorganic materials 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 239000010433 feldspar Substances 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- LNEPOXFFQSENCJ-UHFFFAOYSA-N haloperidol Chemical compound C1CC(O)(C=2C=CC(Cl)=CC=2)CCN1CCCC(=O)C1=CC=C(F)C=C1 LNEPOXFFQSENCJ-UHFFFAOYSA-N 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 238000005470 impregnation Methods 0.000 description 1
- 229910003471 inorganic composite material Inorganic materials 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 239000012263 liquid product Substances 0.000 description 1
- 239000010808 liquid waste Substances 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- PXHVJJICTQNCMI-RNFDNDRNSA-N nickel-63 Chemical compound [63Ni] PXHVJJICTQNCMI-RNFDNDRNSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- JTJMJGYZQZDUJJ-UHFFFAOYSA-N phencyclidine Chemical class C1CCCCN1C1(C=2C=CC=CC=2)CCCCC1 JTJMJGYZQZDUJJ-UHFFFAOYSA-N 0.000 description 1
- 229910052615 phyllosilicate Inorganic materials 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 238000006068 polycondensation reaction Methods 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 229910052573 porcelain Inorganic materials 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 150000004760 silicates Chemical class 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011343 solid material Substances 0.000 description 1
- 239000002900 solid radioactive waste Substances 0.000 description 1
- 230000003381 solubilizing effect Effects 0.000 description 1
- 229910052572 stoneware Inorganic materials 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 229920002994 synthetic fiber Polymers 0.000 description 1
- 238000010257 thawing Methods 0.000 description 1
- 238000009279 wet oxidation reaction Methods 0.000 description 1
- 239000010457 zeolite Substances 0.000 description 1
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
- G21F9/04—Treating liquids
- G21F9/06—Processing
- G21F9/12—Processing by absorption; by adsorption; by ion-exchange
-
- 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
- G21F9/04—Treating liquids
- G21F9/06—Processing
- G21F9/16—Processing by fixation in stable solid media
- G21F9/162—Processing by fixation in stable solid media in an inorganic matrix, e.g. clays, zeolites
- G21F9/165—Cement or cement-like matrix
-
- 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
-
- 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
-
- 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
- G21F9/34—Disposal of solid waste
Definitions
- the present invention refers to a treatment process for exhausted ion exchange resins, in particular a process suitable for treating radioactive ion exchange resins coming from nuclear plants, or resins, below.
- Ion exchange resins are used in nuclear plants, in particular in water reactors, for the removal of any radioactive isotopes present, of corrosion products and other pollutants deriving from the cooling circuit of the reactors themselves. These resins, when the ion exchange capacity is spent, must be replaced with new resins, while the exhausted ones must be managed as radioactive waste, in particular they must be treated and conditioned as radioactive waste.
- This type of radioactive waste constitutes a source of radiation, in particular due to the presence of Cobalt-60 and Nickel-63, products of activation of the steel of the process and structural elements of the reactor.
- the treatment techniques adopted in the nuclear plants for the spent resins are essentially based on five main processes.
- the first process involves the hot supercompaction (350 °C) of the resin, suitably dried, by means of a 2000-ton press acting on a cylindrical container of about 220 litres, provided with bellows to ensure that the integrity of the container itself during compaction is maintained; this process is better known as the Westinhouse-Hansa process.
- the second process is the so-called "Wetoxidation” process and consists of mixing the spent and finely ground resin in hydrogen peroxide brought to high temperature and pressure in which high pressure oxygen is introduced for the chemical demolition of the resin. The obtained liquid product is then subjected to cementation. This process is known as the Ansaldo Nucleare's process.
- the third process involves mixing the spent resin in an epoxy resin matrix after chemical treatment; this method is known as ANDRA's M.E.R.C.U.R.E. method.
- the fourth process consists in the solidification of the resins as they are.
- Portland cements are generally used, which are also mixed with fly ash, blast furnace slag and silica fume, or Geopolymers which are synthetic materials based on aluminosilicates obtained from the reaction of the powder of an aluminosilicate with an alkaline silica solution under conditions of temperature and pressure that are close to the ambient ones.
- the Westinghouse process presents significant complexity of the process itself and a low waste volume reduction factor.
- the Ansaldo Nucleare's process presents process management problems connected with the use of high-pressure oxygen and difficulties in cementing the resulting liquid in the presence of boron, an element which can slow down or even prevent the phenomenon of cement setting or, in the event of dilution, a significant reduction in the volume reduction factor.
- the third one is a process that leads to an increase in the volume of the treated and conditioned waste compared to the initial volume of the waste, the process is also very expensive due to the use of epoxy resins and finally it is not envisaged in the Italian regulation on the disposal of radioactive waste.
- the fourth process involves a very significant increase in the volume of the final waste, since the maximum percentage, in the order of 10% by weight, of the resin that can be mixed in the presence of Boron, to obtain solid matrices with the characteristics necessary for the disposal of radioactive waste is very low.
- the problem underlying the present invention is to make available a treatment process for spent ion exchange resins which allows at least in part to overcome one or more of the drawbacks complained about with reference to the cited known art.
- a further aim is to provide a treatment process for spent ion exchange resins that is reliable, effective, economical and simple to implement and that at the same time complies with the provisions of the regulations for the disposal of low and medium activity radioactive waste.
- the process subject-matter of the present invention relates to a treatment process for ion exchange resins.
- said process comprises a step of mixing said resins with a first admixture A comprising a geopolymer obtained with one or more aluminosilicates.
- said process comprises a step of hyper-compaction of said ion exchange resins, more preferably at a pressure greater than 150 MPa.
- the process according to the invention also allows to reduce the volume of the final product, and to have a cost both of operation and of disposal that is overall cheaper than the processes of prior art.
- said ion exchange resins are radioactive ion exchange resins.
- mixing step is carried out before said hyper-compaction step.
- the compaction of said resins comprises a hyper-compaction of said resins in admixture with said first admixture A.
- the hyper-compaction step allows to reduce both the porosity and the volume of the final product.
- a lower porosity allows to have a greater durability of the material, since the presence of a smaller volume of the pores reduces the possibility of any external agent (e.g. water, acids) penetrating in the material attacking it.
- a reduced porosity also guarantees greater resistance to leaching, a fundamental characteristic for conditioning radioactive waste.
- the aluminosilicates of said first admixture A are selected from the group constituted by fly ash, metakaolin, clay materials and pozzolanic materials.
- said first admixture A comprises NaOH, the ratio by weight between NaOH and aluminosilicates being between 0.3 and 0.4.
- said first admixture A comprises NaOH and KOH, the ratio by weight between NaOH or KOH and aluminosilicates being between 0.3 and 0.4.
- said first admixture A comprises NazSiOs, the ratio by weight between NazSiOs and aluminosilicates being between 0.5 and 1. According to these characteristics, it is possible to realize a final product characterized by excellent mechanical properties, in particular by an advantageous increase in compressive strength.
- the process may comprise a step of mixing said resins with a second admixture B comprising Portland cement.
- Said second admixture B may comprise one or more of the following compounds: NAOH, KOH and A SiOs in addition to the Portland cement.
- the ion exchange resins are fully hydrated.
- the ion exchange resins have a water content greater than 50% by weight.
- the ion exchange resin thus characterized is a completely hydrated resin and therefore the swelling phenomena are substantially eliminated, that is the swelling due to the impregnation of the resins in case of contact with liquid elements (in particular water) that entails a considerable pressure on the matrix, up to causing even destructive fractures thereof.
- the treatment process comprises a pretreatment step before said hyper-compaction step and said mixing step, said pre-treatment step preferably comprising a sub-step of milling the ion exchange resins in order to obtain ion exchange resins in ground form.
- said ion exchange resins in ground form have a dimension less than 150 microns.
- said ion exchange resins in ground form have a dimension less than 50 microns, more preferably between 5 and 50 microns.
- said pre-treatment step comprises a sub-step of milling the resins in order to obtain ion exchange resins in ground form and a sub-step of evaporating the interstitial water of said ion exchange resins, said sub-step of evaporating the interstitial water being after said milling sub-step.
- said sub-step of evaporating the interstitial water also comprises a dehydration sub-step.
- said treatment process for ion exchange resins comprises a solidification step after said hyper-compaction step and said mixing step, said solidification step comprising a conditioning sub-step for disposal as radioactive waste.
- said solidification step comprises a sub-step of heat treatment at a temperature between 40 and 80 °C for a time between 24 and 48 hours before said conditioning sub-step for disposal as radioactive waste.
- This heat treatment favours in particular the completion of the dissolution of the Aluminium and Silica ions, thus encouraging the polymerization process and thus leading to the realization of a geopolymer having improved mechanical characteristics.
- said pre-treatment step comprises a sub-step of extraction of the ion exchange resins from the storage containers, said extraction sub-step being before said milling sub-step.
- the oxidation of the resin can be carried out through potassium permanganate with amounts between 0.7 and 4 kg of permanganate per kilogram of resin at the temperature between 50 and 100 degrees centigrade and pH between 8 and 10.
- the resin is subjected to evaporation before being sent to the treatment steps, preferably by vacuum evaporation plant, until the interstitial water is removed and the degree of water saturation of the resin is around 100%.
- the process of the present invention involves mixing the spent ion exchange resins with substances that can, together with a hypercompaction action, produce a stable solid matrix that can be sent for disposal as low or medium activity solid radioactive waste even without the prior conditioning in cement matrix.
- Hyper-compaction is able to reduce the volume of the waste to be sent for disposal with a ratio on the pre-compaction volume of at least 0.9 and simultaneously improve the mechanical characteristics of the incorporating matrix.
- milling is intended to mean a grinding; herein, milling and grinding are used interchangeably to indicate a process for the controlled reduction of the particle size of a solid material, in particular of an ion exchange resin.
- the process comprises the following steps:
- the spent ion exchange resins are extracted by purifiers or operating columns, the resins are finely ground, until reaching a preferential particle size between 5 and 50 jum, and excess water is removed by evaporation;
- the resins can be oxidized with potassium permanganate preferably in an alkaline environment, with amounts between 0.7 and 4 kg of permanganate per kilogram of resin at a temperature between 50 and 100 degrees centigrade and pH between 8 and 10, in order to reduce the swelling capacity of the resin and improve the mechanical characteristics of the incorporation matrix.
- the resin, which is in the water-dispersed phase, before being sent to the treatment steps is subjected to evaporation, preferably by vacuum evaporation plant, until the interstitial water is removed and that the degree of water saturation of the resin is around 100%;
- binders are constituted by geocements also called geopolymers produced by the activation of fly ash, metakaolin or other substances capable of developing geopolymerization if alkalized, by alkalization with NaOH or KOH and any addition of NazSiOs, possibly admixed to correct the workability of the mixture.
- the solidification admixture being intended for resins with different chemical characteristics, different degrees of saturation and different quantities and species of radionuclides, is calibrated for each type of resin to be treated in order to obtain the best stability on a secular scale of the solid matrices and the minimum leachability of the contained radionuclides.
- measures can be taken, for example to minimize the porosity of the solidified matrix and/or to add further substances such as zeolites and other mineral forms.
- Hyper-compaction step at ambient temperature, with a pressure that is applied very high and greater than 150 MPa. In this way a significant volume reduction besides the interstitial voids of the resins is obtained.
- Hypercompaction is preferably carried out after the pretreatment of the resin, in admixture with the binding components.
- the solidification step provides that the compacted part can remain in an environment with a temperature of 40-80 °C for 24-48 hours in order to maximize the development of geopolymers. Subsequently, the compacted part is sent to conditioning, in compliance with the regulation for the disposal of radioactive waste.
- the conditioning consists in the packaging of the hyper-compacted products of said treatment process preferably in containers in accordance with the ISIN Technical Guide 33 with suitable cement matrix.
- the aluminosilicates of said first admixture A are selected from the group constituted by fly ash, metakaolin, clay materials and pozzolanic materials.
- the first admixture A comprises alkalizing reagents in addition to said one or more aluminosilicates, more preferably it comprises both alkalizing agents and silica-bearing reagents in alkaline environment in the presence of said one or more aluminosilicates.
- Fly ash for reference purpose only, is defined by EN 450-95 standard as follows: Fine powder of essentially spherical and glassy particles, derived from burning of pulverised coal, having pozzolanic properties and consisting essentially of SiOz and AI2O3 with a SiOz content of at least 25%, defined and determined according to the indication of UNI ENV 197/1 -92 standard. Fly ash is widely used to obtain concrete with high mechanical strength, for the obtained reduction of porosity and creep phenomena, consequently increasing the durability of the cement matrix.
- Fly ash is a material that is separated in the cyclones of the smokes, especially in steel plants and thermoelectric power plants.
- the chemical composition of ash is very similar, as mentioned, to that of the natural pozzolans and is composed on average, by way of a non-binding example, of the following components:
- Kaolin is a natural raw material of sedimentary origin that is produced by the action of rainwater on feldspar and is largely constituted by Al2Si2Os(OH)4 kaolinite.
- Kaolinite belongs to the phyllosilicate family wherein the coordination tetrahedra SiC join together to form layers that extend indefinitely into two dimensions.
- Kaolin is used in the production of fine ceramics (earthenware, artistic stoneware and porcelain) or in the production of geopolymers, in particular in the form of metakaolin, that is calcined kaolin at temperatures between 600 and 900 °C.
- the reasons for the treatment subject-matter of the invention lie in the need to stabilize the resin to avoid the swelling phenomenon in case of water saturation of the solid conditioning matrix.
- fly ash or other alumosilicates such as metakaolin are chemically treated in the process in question in order to develop the geopolymers or geocements that significantly improve the characteristics of the matrix incorporating the resins in a solid matrix.
- Geopolymer was introduced in 1970 by Joseph Davidovits, meaning a class of inorganic composite materials obtained by the reaction of a powder with a high silica and alumina content, reactive with an alkaline solution. Geopolymers are thus produced by the activation of a raw material with high aluminosilicate content (greater than 80% by weight) by an alkaline solution constituted by sodium and/or potassium hydroxides and silicates.
- the dissolution of alumino-silica precursors in the activator solution forms oligomers (Si(OH)4 and AI(OH)4) and a subsequent polycondensation reaction connects them forming an amorphous three-dimensional lattice.
- the final arrangement of the atoms in the geopolymer is a function of the Si/AI ratio and of the nature and quantity of the alkaline solution, i.e. the ion that compensates for the presence of Al +3 instead of Si -4 in the tetrahedral structural unit.
- Geopolymers are suitable for the incorporation of the ion exchange resins as they have properties such as high compressive strength, resistance to freezing and thawing cycles, radiation resistance, fire resistance, excellent resistance to chemical agents, both acid ones and salt solutions, low dimensional shrinkage, and low thermal conductivity.
- the binders are constituted by cement mortar, typically prepared with pozzolanic cement of the type EN 197-1 - CEM IV/A 42.5 R possibly mixed with other portland cements, fly ash, silica fume, calcium oxide, alkalizers and additives to optimize strength, processability and setting time.
- the second admixture B comprises one or an admixture among the five types of cement, as classified in EN/171 -1, with or without the addition of the following other compounds: NAOH, KOH, and AI 2 SiO 3 .
- the solidification step involves:
- the powders, the geopolymerizing agents and any additives are mixed which, for the solidification to be facilitated, can remain in an environment with a temperature between 40 and 80 °C for 24-48 hours in order to maximise the development of the geopolymers;
- the compacted material is sent directly to conditioning, in compliance with the regulation for the disposal of radioactive waste.
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Abstract
A treatment process for ion exchange resins, comprising a step of mixing said ion exchange resins with a first admixture (A), comprising a geopolymer which is obtained with one or more aluminosilicates, and a step of hyper-compaction of said ion exchange resins at a pressure greater than 150 MPa.
Description
TREATMENT PROCESS FOR ION EXCHANGE RESINS
DESCRIPTION
Technical scope
The present invention refers to a treatment process for exhausted ion exchange resins, in particular a process suitable for treating radioactive ion exchange resins coming from nuclear plants, or resins, below.
Technological background
Ion exchange resins are used in nuclear plants, in particular in water reactors, for the removal of any radioactive isotopes present, of corrosion products and other pollutants deriving from the cooling circuit of the reactors themselves. These resins, when the ion exchange capacity is spent, must be replaced with new resins, while the exhausted ones must be managed as radioactive waste, in particular they must be treated and conditioned as radioactive waste.
This type of radioactive waste constitutes a source of radiation, in particular due to the presence of Cobalt-60 and Nickel-63, products of activation of the steel of the process and structural elements of the reactor.
The treatment techniques adopted in the nuclear plants for the spent resins are essentially based on five main processes.
The first process involves the hot supercompaction (350 °C) of the resin, suitably dried, by means of a 2000-ton press acting on a cylindrical container of about 220 litres, provided with bellows to ensure that the integrity of the container itself during compaction is maintained; this process is better known as the Westinhouse-Hansa process.
The second process is the so-called "Wetoxidation" process and consists of mixing the spent and finely ground resin in hydrogen peroxide brought to high temperature and pressure in which high pressure oxygen is introduced for the chemical demolition of the resin. The obtained liquid product is then subjected to cementation. This process is known as the Ansaldo Nucleare's process.
The third process involves mixing the spent resin in an epoxy resin matrix after chemical treatment; this method is known as ANDRA's M.E.R.C.U.R.E. method.
The fourth process consists in the solidification of the resins as they are. Portland cements are generally used, which are also mixed with fly ash, blast furnace slag and silica fume, or Geopolymers which are synthetic materials based on aluminosilicates obtained from the reaction of the powder of an aluminosilicate with an alkaline silica solution under conditions of temperature and pressure that are close to the ambient ones.
Each of these processes has some major drawbacks, some examples of which are reported below.
The Westinghouse process presents significant complexity of the process itself and a low waste volume reduction factor.
The Ansaldo Nucleare's process presents process management problems connected with the use of high-pressure oxygen and difficulties in cementing the resulting liquid in the presence of boron, an element which can slow down or even prevent the phenomenon of cement setting or, in the event of dilution, a significant reduction in the volume reduction factor. The third one is a process that leads to an increase in the volume of the
treated and conditioned waste compared to the initial volume of the waste, the process is also very expensive due to the use of epoxy resins and finally it is not envisaged in the Italian regulation on the disposal of radioactive waste.
The fourth process, the direct solidification, involves a very significant increase in the volume of the final waste, since the maximum percentage, in the order of 10% by weight, of the resin that can be mixed in the presence of Boron, to obtain solid matrices with the characteristics necessary for the disposal of radioactive waste is very low.
Description of the invention
The problem underlying the present invention is to make available a treatment process for spent ion exchange resins which allows at least in part to overcome one or more of the drawbacks complained about with reference to the cited known art.
A further aim is to provide a treatment process for spent ion exchange resins that is reliable, effective, economical and simple to implement and that at the same time complies with the provisions of the regulations for the disposal of low and medium activity radioactive waste.
This problem is solved and such aims are achieved by the invention by means of a treatment process for spent ion exchange resins comprising one or more of the features mentioned in the attached claims.
The process subject-matter of the present invention relates to a treatment process for ion exchange resins.
Preferably said process comprises a step of mixing said resins with a first
admixture A comprising a geopolymer obtained with one or more aluminosilicates.
Preferably said process comprises a step of hyper-compaction of said ion exchange resins, more preferably at a pressure greater than 150 MPa.
Thanks to these characteristics, it is possible to have a process that allows to realize a final product of high resistance, both with compression, with thermal cycles, and with the action of chemical agents and at the same time having a low dimensional shrinkage.
The process according to the invention also allows to reduce the volume of the final product, and to have a cost both of operation and of disposal that is overall cheaper than the processes of prior art.
Preferably, said ion exchange resins are radioactive ion exchange resins.
Preferably said mixing step is carried out before said hyper-compaction step.
In this case, it is therefore found that the compaction of said resins comprises a hyper-compaction of said resins in admixture with said first admixture A.
In this way, the hyper-compaction step allows to reduce both the porosity and the volume of the final product. A lower porosity allows to have a greater durability of the material, since the presence of a smaller volume of the pores reduces the possibility of any external agent (e.g. water, acids) penetrating in the material attacking it. In addition, a reduced porosity also guarantees greater resistance to leaching, a fundamental characteristic for conditioning radioactive waste.
In some embodiments the aluminosilicates of said first admixture A are
selected from the group constituted by fly ash, metakaolin, clay materials and pozzolanic materials.
In some embodiments said first admixture A comprises NaOH, the ratio by weight between NaOH and aluminosilicates being between 0.3 and 0.4.
In some embodiments said first admixture A comprises NaOH and KOH, the ratio by weight between NaOH or KOH and aluminosilicates being between 0.3 and 0.4.
In some embodiments said first admixture A comprises NazSiOs, the ratio by weight between NazSiOs and aluminosilicates being between 0.5 and 1. According to these characteristics, it is possible to realize a final product characterized by excellent mechanical properties, in particular by an advantageous increase in compressive strength.
According to a variant of the solution, the process may comprise a step of mixing said resins with a second admixture B comprising Portland cement. Said second admixture B may comprise one or more of the following compounds: NAOH, KOH and A SiOs in addition to the Portland cement.
Preferably, in the hyper-compaction step the ion exchange resins are fully hydrated.
Preferably, in the hyper-compaction step the ion exchange resins have a water content greater than 50% by weight.
In this way, the ion exchange resin thus characterized is a completely hydrated resin and therefore the swelling phenomena are substantially eliminated, that is the swelling due to the impregnation of the resins in case of contact with liquid elements (in particular water) that entails a considerable pressure on the matrix, up to causing even destructive
fractures thereof.
In a preferred embodiment the treatment process comprises a pretreatment step before said hyper-compaction step and said mixing step, said pre-treatment step preferably comprising a sub-step of milling the ion exchange resins in order to obtain ion exchange resins in ground form. Preferably said ion exchange resins in ground form have a dimension less than 150 microns.
Preferably said ion exchange resins in ground form have a dimension less than 50 microns, more preferably between 5 and 50 microns.
In this way it is advantageously possible to obtain a final product characterized by a greater homogeneity with respect to the products obtained by the processes of the prior art, as well as to further reduce the swelling phenomena of the resin. Furthermore, the fact of incorporating resin particles having such dimensional characteristics greatly inhibits the formation of microfractures in the matrix, which could lead to a weakening of the same.
In a preferred embodiment, said pre-treatment step comprises a sub-step of milling the resins in order to obtain ion exchange resins in ground form and a sub-step of evaporating the interstitial water of said ion exchange resins, said sub-step of evaporating the interstitial water being after said milling sub-step.
In this way, the risk of weakening or compromising the resin-geopolymer admixture due to the presence of excess interstitial water which may reside outside the resin particles is minimized.
In a more preferred embodiment, said sub-step of evaporating the
interstitial water also comprises a dehydration sub-step.
In some embodiments said treatment process for ion exchange resins comprises a solidification step after said hyper-compaction step and said mixing step, said solidification step comprising a conditioning sub-step for disposal as radioactive waste.
Preferably said solidification step comprises a sub-step of heat treatment at a temperature between 40 and 80 °C for a time between 24 and 48 hours before said conditioning sub-step for disposal as radioactive waste.
This heat treatment favours in particular the completion of the dissolution of the Aluminium and Silica ions, thus encouraging the polymerization process and thus leading to the realization of a geopolymer having improved mechanical characteristics.
In some embodiments said pre-treatment step comprises a sub-step of extraction of the ion exchange resins from the storage containers, said extraction sub-step being before said milling sub-step.
Preferably, in the pre-treatment step the oxidation of the resin can be carried out through potassium permanganate with amounts between 0.7 and 4 kg of permanganate per kilogram of resin at the temperature between 50 and 100 degrees centigrade and pH between 8 and 10.
In this way, the swelling capacity of the resin is greatly reduced and the mechanical characteristics of the incorporating matrix are improved.
Preferably, the resin is subjected to evaporation before being sent to the treatment steps, preferably by vacuum evaporation plant, until the interstitial water is removed and the degree of water saturation of the resin is around 100%.
Brief description of the drawings
The characteristics and the advantages of the invention will become clearer from the detailed description of some illustrated embodiments, by way of non-limiting example, with reference to what is illustrated in the figures in which:
- Figure 1 reports a diagram of the steps of the process according to the present invention (process diagram 1);
- Figure 2 reports a diagram of the steps of the process according to a variant of the solution (process diagram 2); and
- Figure 3 reports a ternary diagram CaO/SiCh/A Cb.
Preferred embodiment of the invention
The process of the present invention, called the HYPEX® process, acronym for HYPercompaction of ion Exchange resins, involves mixing the spent ion exchange resins with substances that can, together with a hypercompaction action, produce a stable solid matrix that can be sent for disposal as low or medium activity solid radioactive waste even without the prior conditioning in cement matrix.
Hyper-compaction is able to reduce the volume of the waste to be sent for disposal with a ratio on the pre-compaction volume of at least 0.9 and simultaneously improve the mechanical characteristics of the incorporating matrix.
Within the scope of the present disclosure, the term "milling" is intended to mean a grinding; herein, milling and grinding are used interchangeably to
indicate a process for the controlled reduction of the particle size of a solid material, in particular of an ion exchange resin.
The process comprises the following steps:
- pre-treatment step: in this step, the spent ion exchange resins are extracted by purifiers or operating columns, the resins are finely ground, until reaching a preferential particle size between 5 and 50 jum, and excess water is removed by evaporation; in the pretreatment step of said process, the resins can be oxidized with potassium permanganate preferably in an alkaline environment, with amounts between 0.7 and 4 kg of permanganate per kilogram of resin at a temperature between 50 and 100 degrees centigrade and pH between 8 and 10, in order to reduce the swelling capacity of the resin and improve the mechanical characteristics of the incorporation matrix. The resin, which is in the water-dispersed phase, before being sent to the treatment steps is subjected to evaporation, preferably by vacuum evaporation plant, until the interstitial water is removed and that the degree of water saturation of the resin is around 100%;
- mixing step: in this step, the ground resin deprived of the interstitial water is mixed with the binding agents that will cause solidification.
These binders are constituted by geocements also called geopolymers produced by the activation of fly ash, metakaolin or other substances capable of developing geopolymerization if alkalized, by alkalization with NaOH or KOH and any addition of NazSiOs, possibly admixed to correct the workability of the mixture.
The solidification admixture, being intended for resins with different
chemical characteristics, different degrees of saturation and different quantities and species of radionuclides, is calibrated for each type of resin to be treated in order to obtain the best stability on a secular scale of the solid matrices and the minimum leachability of the contained radionuclides. In this step, measures can be taken, for example to minimize the porosity of the solidified matrix and/or to add further substances such as zeolites and other mineral forms.
- Hyper-compaction step at ambient temperature, with a pressure that is applied very high and greater than 150 MPa. In this way a significant volume reduction besides the interstitial voids of the resins is obtained. Hypercompaction is preferably carried out after the pretreatment of the resin, in admixture with the binding components.
- Solidification step: for the process sequence according to the preferred embodiment reported in Figure 1, which involves mixing the resins with the binding matrix before hyper-compaction, the solidification step provides that the compacted part can remain in an environment with a temperature of 40-80 °C for 24-48 hours in order to maximize the development of geopolymers. Subsequently, the compacted part is sent to conditioning, in compliance with the regulation for the disposal of radioactive waste. The conditioning consists in the packaging of the hyper-compacted products of said treatment process preferably in containers in accordance with the ISIN Technical Guide 33 with suitable cement matrix.
According to a preferred embodiment, the aluminosilicates of said first admixture A are selected from the group constituted by fly ash, metakaolin, clay materials and pozzolanic materials.
Preferably, the first admixture A comprises alkalizing reagents in addition to said one or more aluminosilicates, more preferably it comprises both alkalizing agents and silica-bearing reagents in alkaline environment in the presence of said one or more aluminosilicates.
Fly ash, for reference purpose only, is defined by EN 450-95 standard as follows: Fine powder of essentially spherical and glassy particles, derived from burning of pulverised coal, having pozzolanic properties and consisting essentially of SiOz and AI2O3 with a SiOz content of at least 25%, defined and determined according to the indication of UNI ENV 197/1 -92 standard. Fly ash is widely used to obtain concrete with high mechanical strength, for the obtained reduction of porosity and creep phenomena, consequently increasing the durability of the cement matrix.
The ternary diagram reported in Figure 3 highlights the ash-natural pozzolan affinity in terms of chemical composition and shows the differences with other commonly used materials
Fly ash is a material that is separated in the cyclones of the smokes, especially in steel plants and thermoelectric power plants.
The chemical composition of ash is very similar, as mentioned, to that of the natural pozzolans and is composed on average, by way of a non-binding example, of the following components:
Kaolin is a natural raw material of sedimentary origin that is produced by the action of rainwater on feldspar and is largely constituted by Al2Si2Os(OH)4 kaolinite. Kaolinite belongs to the phyllosilicate family wherein the coordination tetrahedra SiC join together to form layers that extend indefinitely into two dimensions.
Kaolin is used in the production of fine ceramics (earthenware, artistic stoneware and porcelain) or in the production of geopolymers, in particular in the form of metakaolin, that is calcined kaolin at temperatures between 600 and 900 °C.
The reasons for the treatment subject-matter of the invention lie in the need to stabilize the resin to avoid the swelling phenomenon in case of water saturation of the solid conditioning matrix. A phenomenon, directly linked according to the scientific literature, to the osmotic pressure that the resin exerts in the intake of water until it reaches water saturation. The extent of this osmotic pressure depends on the ion exchange capacity of the resin, its functional group, the ionic form and in particular the degree of saturation in water.
In order to obtain a binding matrix with adequate mechanical strength characteristics to counteract the swelling pressure of the resins, fly ash or
other alumosilicates such as metakaolin are chemically treated in the process in question in order to develop the geopolymers or geocements that significantly improve the characteristics of the matrix incorporating the resins in a solid matrix.
The term "geopolymer" was introduced in 1970 by Joseph Davidovits, meaning a class of inorganic composite materials obtained by the reaction of a powder with a high silica and alumina content, reactive with an alkaline solution. Geopolymers are thus produced by the activation of a raw material with high aluminosilicate content (greater than 80% by weight) by an alkaline solution constituted by sodium and/or potassium hydroxides and silicates.
In detail, the dissolution of alumino-silica precursors in the activator solution forms oligomers (Si(OH)4 and AI(OH)4) and a subsequent polycondensation reaction connects them forming an amorphous three-dimensional lattice. The final arrangement of the atoms in the geopolymer is a function of the Si/AI ratio and of the nature and quantity of the alkaline solution, i.e. the ion that compensates for the presence of Al+3 instead of Si-4 in the tetrahedral structural unit.
Geopolymers are suitable for the incorporation of the ion exchange resins as they have properties such as high compressive strength, resistance to freezing and thawing cycles, radiation resistance, fire resistance, excellent resistance to chemical agents, both acid ones and salt solutions, low dimensional shrinkage, and low thermal conductivity.
The effectiveness of the solidification of the radioactive ion exchange resins with geopolymer matrices that have shown the regulatory requirements for
disposal as low or medium activity radioactive waste has also already been demonstrated.
The advantages of the present invention in addition to those described above can be substantially summarized, but not limited, in the following points:
- method carried out cold or at a slightly higher temperature than the ambient temperature;
- elimination or containment of the swelling phenomenon to which a stable final matrix corresponds;
- use of conventional containers (drums);
- reduction of the secondary liquid waste generated in the hypercompaction step to a minimum amount;
- reduction of the voids of the treated and compacted resin;
- reduced operating costs.
It goes without saying that, in order to meet specific and contingent application needs, a person skilled in the art will be able to make further modifications and variants to the solution described above that are nevertheless within the scope of protection as defined by the following claims.
According to a variant of the solution, the binders are constituted by cement mortar, typically prepared with pozzolanic cement of the type EN 197-1 - CEM IV/A 42.5 R possibly mixed with other portland cements, fly ash, silica fume, calcium oxide, alkalizers and additives to optimize strength, processability and setting time.
In some embodiments the second admixture B comprises one or an
admixture among the five types of cement, as classified in EN/171 -1, with or without the addition of the following other compounds: NAOH, KOH, and AI2SiO3.
In the treatment process in question, the following two types of cement were taken as a reference for the formulation of the solidification formula of the spent radioactive ion exchange resins with cement matrix:
- high-strength pozzolanic ferric cement (EN 197-1 - CEM IV / A 42.5) containing 65% 89% clinker and the remaining part is constituted by natural pozzolan and any secondary constituents. This cement ensures high mechanical strengths, high sulphate resistance, high resistance to the solubilizing action from runoff water and a reduced hydration heat. The high fineness of this cement results in a low permeability in favour of the durability of the matrix; ferric portland cement EN 197-1 - CEM I 42,5 N containing, in compliance with the composition prescribed by the UNI EN 197-1 standard, 95% 100% clinker free of tricalcium aluminate, while the remaining part is constituted by any secondary constituents. This cement has very high sulphate resistance and high acid water resistance as it is free of C3A.
For the process sequence according to the variant of the solution reported in Figure 2, which involves mixing the resins with the binding matrix after hyper-compaction, the solidification step involves:
- in case of use of the geopolymer matrix, the powders, the geopolymerizing agents and any additives are mixed which, for the solidification to be facilitated, can remain in an environment with a temperature between 40 and 80 °C for 24-48 hours in order to maximise the development of the
geopolymers;
- in case of use of the cement matrix, the compacted material is sent directly to conditioning, in compliance with the regulation for the disposal of radioactive waste.
Claims
CLAIMS A treatment process for ion exchange resins, comprising a step of mixing said ion exchange resins with a first admixture (A), comprising a geopolymer which is obtained with one or more aluminosilicates, and a step of hyper-compaction of said ion exchange resins at a pressure greater than 150 MPa. A treatment process for ion exchange resins according to claim 1, wherein said mixing step is carried out before said hyper-compaction step. A treatment process for ion exchange resins according to claim 1 or claim 2, wherein said aluminosilicates of said first admixture (A) are selected from the group constituted by fly ash, metakaolin, clay materials and pozzolanic materials. A treatment process for ion exchange resins according to one or more of the preceding claims, wherein said first admixture (A) comprises NaOH and NazSiOs, the ratio by weight between NaOH and aluminosilicates being between 0.3 and 0.4 and the ratio by weight between NazSiOs and aluminosilicates being between 0.5 and 1. A treatment process for ion exchange resins according to one or more of the preceding claims, wherein said ion exchange resins are radioactive. A treatment process for ion exchange resins according to any one of the preceding claims, wherein in said hyper-compaction step the ion exchange resins have a water content greater than 50% by weight. A treatment process for ion exchange resins according to one or more of the preceding claims, comprising a pre-treatment step before said hypercompaction step and said mixing step, said pre-treatment step
comprising a sub-step of milling the ion exchange resins in order to obtain ion exchange resins in ground form, preferably with dimension less than 50 microns. A treatment process for ion exchange resins according to claim 7, wherein said pre-treatment step comprises a sub-step of evaporating the interstitial water of said ion exchange resins after said milling sub-step. A treatment process for ion exchange resins according to one or more of the preceding claims, comprising a solidification step after said hypercompaction step and said mixing step, said solidification step comprising a conditioning sub-step for disposal as radioactive waste. . A treatment process for ion exchange resins according to claim 9, wherein said solidification step comprises a sub-step of heat treatment at a temperature between 40 and 80 °C for a time between 24 and 48 hours before said conditioning sub-step for disposal as radioactive waste when said mixing step is carried out with said first admixture (A).
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| IT202200006416 | 2022-03-31 |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4906408A (en) * | 1987-12-02 | 1990-03-06 | Commissariat A L'energie Atomique | Means for the conditioning of radioactive or toxic waste in cement and its production process |
| GB2485014A (en) * | 2010-10-27 | 2012-05-02 | Voro Ltd | Waste disposal |
-
2023
- 2023-03-31 WO PCT/IB2023/053257 patent/WO2023187740A1/en unknown
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4906408A (en) * | 1987-12-02 | 1990-03-06 | Commissariat A L'energie Atomique | Means for the conditioning of radioactive or toxic waste in cement and its production process |
| GB2485014A (en) * | 2010-10-27 | 2012-05-02 | Voro Ltd | Waste disposal |
Non-Patent Citations (1)
| Title |
|---|
| FUNABASHI K ET AL: "PROPERTIES OF A RADIOACTIVE WASTE PELLET PACKAGE USING CEMENT-GLASS", NUCLEAR TECHNOLOGY, AMERICAN NUCLEAR SOCIETY, CHICAGO, IL, US, vol. 96, no. 2, 1 November 1991 (1991-11-01), pages 185 - 191, XP000242038, ISSN: 0029-5450 * |
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