Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/24—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing alkyl, ammonium or metal silicates; containing silica sols
  • C04B28/26—Silicates of the alkali metals
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/006—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing mineral polymers, e.g. geopolymers of the Davidovits type
  • C04B28/008—Mineral polymers other than those of the Davidovits type, e.g. from a reaction mixture containing waterglass
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
  • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
  • C04B2111/00767—Uses not provided for elsewhere in C04B2111/00 for waste stabilisation purposes
• • 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
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P40/00—Technologies relating to the processing of minerals
  • Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding
• • 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

• alkaline compounds such as sodium, potassium, lithium in significant amounts. This is the case, for example, with metal pickling baths.
• Waste storage is regulated by strict regulations.
• a waste, to be eligible is in particular to fulfill criteria at the level of the pH of the leaching water, the global soluble fraction and the dryness.
• a 10N sodium hydroxide subjected to such a solidification treatment by cementation does not make it possible to obtain a material whose pH of the leaching water is less than 13.
• the object of the invention is therefore to propose a process for preparing a solid material from an alkaline hydroxide or a precursor thereof in a solid material that complies with the regulations, including the X30417 standard.
• Solid material is considered to be in compliance with regulations when:
• the leaching water has a pH of less than 13;
• the soluble fraction is less than 10%
• the invention is based on the observation that an aqueous solution containing an alkaline hydroxide, a calcium salt and silicon oxide is transformed in a few weeks into a very poorly soluble solid material.
• the invention therefore proposes a process for preparing a solid material from an alkaline hydroxide or a precursor thereof, comprising the step of:
• the alkali hydroxide may be lithium, sodium, potassium, rubidium, cesium, or francium hydroxide. Preferably, it is sodium hydroxide or potassium hydroxide.
• alkaline hydroxide precursors is intended to mean compounds capable of releasing alkaline hydroxides in aqueous solution.
• a precursor mention may in particular be made of carbonates and oxides.
• the precursor is an alkaline carbonate.
• the alkaline hydroxide is in concentrated aqueous solution, in particular 1N, or more preferably 1ON, until saturation. It can also be in supersaturated solution or even in dispersion.
• the preferred calcium compound is calcium carbonate. This may, however, be replaced or mixed with another calcium compound such as chloride, bromide, sulphate, nitrate or phosphate.
• the calcium compound and / or silicon oxide constitute waste.
• the calcium compound is preferably added in powder form.
• the calcium compound has a particle diameter at 100% less than 1000 ⁇ m, more preferably less than 500 ⁇ m and most particularly less than 100 ⁇ m. Chalk is particularly appropriate.
• the silicon oxide is preferably also in powder form.
• the silicon oxide has a particle diameter at 100% less than 1000 ⁇ m, more preferably less than 500 ⁇ m and most particularly less than 100 ⁇ m.
• the silica is in a form other than quartz, which is not very reactive.
• the calcium compound and the silicon oxide are added in the form of a silico-limestone compound such as sand-lime sand, fly ash, slag or slag.
• a silico-limestone compound such as sand-lime sand, fly ash, slag or slag.
• the process can be operated either continuously or batchwise.
• Its implementation is very simple, and includes the step of contacting the alkaline hydroxide solution with the calcium compound and the silicon oxide.
• the proportions of the reagents can vary to a large extent. As an indication, the addition of the reagents in a molar ratio of 0.1 to 10 relative to the alkali hydroxide or its precursor is adapted to give satisfactory results.
• 0.1 to 5 moles of calcium compound are added per mole of alkali hydroxide or precursor.
• 0.1 to 5 moles of silicon oxide are added per mole of alkali hydroxide or precursor.
• the different ingredients are mixed during the different ingredients.
• the calcium compound and the silicon oxide may be added to the alkaline hydroxide simultaneously or successively.
• the calcium compound and the silicon oxide are dispersed separately in the alkaline hydroxide or its precursor before mixing the two dispersions.
• the dispersions can be mixed immediately or not after their preparation. This embodiment has the advantage of reducing the amount of reagent necessary to solidify the alkaline hydroxide or its precursor, all conditions being equal.
• the amount of reagents necessary to solidify 100 parts by weight of 10N NaOH can be reduced by 39.4 parts by weight of CaCO 3 (powder ⁇ 600 ⁇ m) and 80 parts of SiO 2 with 27 parts by weight CaCO 3 (powder ⁇ 600 ⁇ m) and 70 parts of SiO 2 .
• the product may be in the form of granules, putty or paste or grout.
• reaction usually takes place within a few days or weeks at room temperature.
• the product obtained can then be converted into monolithic material. It can be set up for example by pouring, pumping, compression or vibrocompaction.
• the process according to the invention is all the more surprising since sodium hydroxide has a high solubility (420 g per liter), like almost all of the sodium compounds, and is solidified by a calcium salt and silicon dioxide, which are poorly soluble in water and not very reactive.
• the process according to the invention is easy to implement and very economical, since it requires cheap reagents, preferably from quarries. Their obtaining therefore consumes little energy and is not polluting.
• the calcium compound is itself derived from waste.
• the process does not require thermal energy input and does not require expensive and complicated equipment, and poses no particular danger to the staff and the environment. Furthermore, the process according to the invention does not create gaseous or liquid discharges into the environment and is therefore ecologically clean.
• the process according to the invention can also be used to coat other wastes and thus isolate them physically and chemically. This variant is particularly interesting for example to trap the elements likely to flow.
• the solution being solidified contains silico-calcium hydrates which generally have a high specific surface, of the order of a few hundred m 2 / g. This makes it possible to trap the elements likely to flow from waste into the solidified product.
• the invention therefore relates to a method for storing solid waste that is insoluble in water, comprising the following steps:
• the waste can be waste of any kind. Preferably, it is graphite parts. Especially preferred are toxic and / or radioactive waste under the laws and regulations.
• the solid material obtained meets the regulatory requirements in force in France for the storage of waste.
• the solid material preferably has: - leaching water with a pH below 13;
• the invention also relates to a solid material that can be obtained by the process described above.
• the rate of solidification of the material is sufficiently high to allow its use or storage immediately after manufacture.
• the product obtained can therefore be stored directly.
• the solid material can be used for example on a construction site, to form works such as grout, slabs, pavement or to be used for filling cavities or in a prefabrication plant. It can also be stored in an ultimate tailings storage facility or in a landfill.
• the invention thus aims at the use of the solidified products obtained for the construction of construction works and for the storage of solid waste.
• EXAMPLE 1 1000 kg of sodium hydroxide solution 16.7 N is added 700 kg of calcium chloride in the form of industrial residue, and 640 kg of silicon oxide from a quarry whose particle diameter is 100% less than 1000 .mu.m. At maturity of 28 days a solid material is obtained. It is subjected for 24 hours to the leaching test according to the standard X 30417. The pH of the solution is less than 13, the soluble fraction is less than 10%, the dryness greater than 35% by weight.
• Cylindrical graphite elements have a diameter of 135 mm and a height of 600 mm of a weight of 11 kg, are immersed in the freshly prepared solution according to Example 2.
• This matrix provides hardening physical and chemical insulation and a trapping in situ of pollutants that may be contained in graphite, for example radioactive isotopes.

Landscapes

• Chemical & Material Sciences (AREA)
• Ceramic Engineering (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Chemistry (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• Geology (AREA)
• Geochemistry & Mineralogy (AREA)
• Life Sciences & Earth Sciences (AREA)
• Processing Of Solid Wastes (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)
• Compounds Of Unknown Constitution (AREA)
• Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)

Applications Claiming Priority (3)

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• 2006
  • 2006-02-21 EP EP06725977A patent/EP1851179A2/de not_active Withdrawn
  • 2006-02-21 KR KR20077020945A patent/KR20070107762A/ko not_active Application Discontinuation
  • 2006-02-21 CA CA 2597943 patent/CA2597943A1/fr not_active Abandoned
  • 2006-02-21 WO PCT/FR2006/000392 patent/WO2006087484A2/fr active Application Filing

Non-Patent Citations (1)

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