WO2021112163A1 - Layered manganese oxide molded body and method for producing same - Google Patents

Layered manganese oxide molded body and method for producing same Download PDF

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WO2021112163A1
WO2021112163A1 PCT/JP2020/044990 JP2020044990W WO2021112163A1 WO 2021112163 A1 WO2021112163 A1 WO 2021112163A1 JP 2020044990 W JP2020044990 W JP 2020044990W WO 2021112163 A1 WO2021112163 A1 WO 2021112163A1
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manganese oxide
molded product
layered manganese
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layered
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PCT/JP2020/044990
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French (fr)
Japanese (ja)
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陵二 田中
尚登 西山
藤井　康浩
望水 井手
由布子 深田
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東ソー株式会社
公益財団法人相模中央化学研究所
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Priority to JP2021562706A priority Critical patent/JPWO2021112163A1/ja
Publication of WO2021112163A1 publication Critical patent/WO2021112163A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G45/00—Compounds of manganese
    • 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

Definitions

  • the present invention relates to a layered manganese oxide molded product and a method for producing the same.
  • the operation of adsorbing and separating harmful or useful ions from an aqueous solution using a solid phase adsorbent is important as a separation technique because it does not involve concentration of a high-cost aqueous solution.
  • the adsorption of strontium ions is particularly important because strontium is produced in a large amount in fission products in uranium fission-type nuclear power generation and the strontium concentration has a low wastewater standard value.
  • Manganese oxide has been widely known as a material capable of selectively adsorbing and separating strontium.
  • Patent Document 1 discloses a layered manganese oxide having sodium ions in the layers, which is synthesized by a solid phase reaction method in which a manganese raw material and a sodium raw material are mixed and fired as an adsorbent for strontium ions in seawater.
  • Patent Document 2 discloses a layered manganese oxide having potassium ions in the layers, which is also synthesized by a solid-phase reaction method in which a manganese raw material and a potassium raw material are mixed and fired as an adsorbent for strontium ions in seawater. There is.
  • Non-Patent Document 1 As an adsorbent for radionuclides containing strontium, a burnesite-type layered manganese oxide is disclosed in Non-Patent Document 1. This substance is obtained by reacting a manganese hydroxide sol with magnesium permanganate and aging under high alkaline conditions (pH 13.7) for 7 days.
  • the bulk density of the molded product prepared from the layered manganese oxide powder synthesized by the solid phase reaction method and the inorganic binder is often low.
  • the bulk density is high without containing components such as a binder other than the adsorbent.
  • the layered manganese oxide molded product synthesized by the solid-phase reaction method has poor shape retention during water flow. If the shape retention is poor, there is a disadvantage that the layered manganese oxide molded product becomes muddy and difficult to handle when it is pulverized to block the flow path of the adsorption tower or when the layered manganese oxide molded product is taken out from the adsorption tower. Therefore, it is expected that the use of a layered manganese oxide molded product synthesized by the solid-phase reaction method for the treatment of contaminated water at a nuclear power plant will cause a big problem when disposing of the radioactive molded product.
  • the present invention solves these problems and provides a layered manganese oxide molded product that simultaneously establishes sufficient strontium adsorption performance, mechanical strength, and shape retention without any trouble.
  • a solid phase synthesis method in which raw materials are mixed and calcined, or a reaction between a permanganate and a manganese salt in an aqueous solution is performed.
  • an inorganic binder and a thickener composed of an organic substance are added and kneaded, then molded into a noodle shape using an extrusion molding machine, dried, and then crushed. A complicated manufacturing process was required.
  • the present invention solves this problem, and the layered manganese oxide molded product of the present invention can be produced by a simple process such as filtration, drying, and crushing after a wet reaction.
  • the present inventor has found that the strength, shape retention and adsorption performance are all satisfied at a high level. , The present invention has been completed. That is, the present invention has the following configurations.
  • the layered manganese oxide molded product according to one aspect of the present invention is composed of a layered manganese oxide containing at least an alkali metal and manganese, and has a crushing strength of 1000 mN or more and 5000 mN or less as measured by a microcompression tester. It has, does not contain an inorganic binder and an organic component, and 90% or more of all the granules are granules having a particle size of 0.2 mm or more and 1.7 mm or less, and a bulk density of 0.9 g / cm 3 or more.
  • the present invention has both strontium adsorption performance, mechanical strength, and shape retention, and is a layered manganese oxide that does not contain a binder that is inert to adsorption.
  • the molded product can be provided by a simple and cost-effective manufacturing method.
  • the layered manganese oxide molded product of the present invention is composed of a layered manganese oxide containing at least an alkali metal and manganese.
  • the layered A-Mn oxide represented by the composition formula A x MnO 2 and represented by at least one alkali metal selected from sodium and potassium differs in the size of the crystal lattice in the dry and wet states. It is preferable in that there is no such thing and it is possible to suppress the collapse of the molded body during water flow.
  • the alkali metal at least one of sodium and potassium can be used, and a mixture of both alkali metals may be used.
  • the alkali metal potassium is preferable because it can suppress changes in lattice volume during drying and wetting of the layered manganese oxide molded product of the present invention and can maintain shape retention during water flow.
  • A is an alkali metal
  • x represents the A / Mn molar ratio, that is, the range of x can be represented by 0.2 ⁇ x ⁇ 0.6, among which 0.3 ⁇ x ⁇ 0.5.
  • the layered manganese oxide molded product of the present invention has high strontium adsorption performance, which is more preferable.
  • the layered manganese oxide molded product containing both alkali metals of sodium and potassium and having 0.4 ⁇ x ⁇ 0.6 has higher strontium adsorption performance.
  • the oxygen composition varies slightly due to the formation of an empty lattice, it can be regarded as an integer value of 2. Further, water may be contained between the layers of the layered manganese oxide constituting the manganese oxide molded product of the present invention or between the particles.
  • the interlayer distance between the constituent layered manganese oxides is 7.0 angstroms or more and 7.3 angstroms or less. Is preferable. If this range is exceeded, the inside of the molded product may be distorted due to the volume change from the dry state to the wet state, and the layered manganese oxide molded product of the present invention may collapse.
  • the interlayer distance of the layered manganese oxide molded product of the present invention is the lowest angular diffraction peak of the powder X-ray diffraction pattern, and the 001 peak position (angle) when assigned by hexagonal crystals is converted into the plane spacing (angstrom). It can be obtained by.
  • the FWHM is preferably 0.4 ° or more and 3.5 ° or less, more preferably 0.4 ° or more and 3.0 ° or less, and further preferably 0.7 ° or more and 2.2 ° or less.
  • the FWHM of the 001 peak when assigned as a hexagon in the powder X-ray diffraction experiment is 2.5 ° or more. It was found that the layered manganese oxide molded product having a temperature of 3.5 ° or less has higher strontium adsorption performance.
  • the layered manganese oxide molded product of the present invention is characterized in that it exhibits a high crushing strength of 1000 mN or more and 5000 mN or less as measured by a microcompression tester. If it is less than 1000 mN as measured by a microcompression tester, the mechanical strength is insufficient, and if it exceeds 5000 mN, the porosity is impaired and the strontium adsorption performance is lowered. From the viewpoint of shape retention and strontium adsorption performance, the crushing strength is preferably 2000 mN or more and 4000 mN or less.
  • the layered manganese oxide molded product of the present invention preferably has a stirring wear degree of 15% by weight or less, which is an index for evaluating the shape retention of the molded product during water flow.
  • the degree of agitation wear can be measured in accordance with JIS-K-1464 (wear test of industrial desiccant).
  • the layered manganese oxide molded product of the present invention is characterized by containing no inorganic binder and no organic component.
  • the fact that the inorganic binder and the organic component are not contained means that the measurement means is below the detection limit.
  • the adsorption performance can be improved, and the strength and shape retention of the molded product can be maintained.
  • Colloidal particles such as silicon, aluminum, titanium and zirconium components, as well as layered or fibrous silicates, specifically bentonite and sepiolite, can be listed as common inorganic binders of the present invention.
  • the layered manganese oxide molded product does not contain these.
  • the molded product does not contain an organic component, and it is preferable that the carbon concentration in the molded product is 3000 ppm or less, that is, not more than the detection limit of each measuring means.
  • the carbon concentration in the molded product is 3000 ppm or less, that is, not more than the detection limit of each measuring means.
  • it can be obtained by back-calculating from the amount of CO or CO 2 produced by high-temperature combustion of a sample.
  • the layered manganese oxide molded product of the present invention does not contain an inorganic binder or an organic thickener, all the molded products function for adsorption and increase the bulk density, so that the amount of the layered manganese oxide molded product is larger than that of a fixed volume adsorption tower. It can be filled with heavy adsorbents. Furthermore, despite the fact that no binder is used, it is possible to achieve strong mechanical strength and shape retention during water flow only by electrostatic agglomeration of particles.
  • 90% or more of the whole grains are granules having a particle size of 0.2 mm or more and 1.7 mm or less. If the particle size of 0.2 mm or more and 1.7 mm or less is less than 90% of the whole grains, the particle size distribution becomes wide and the performance of the adsorption tower deteriorates. If the particles having a particle size of less than 0.2 mm exceed 10% of the total particles, there is an adverse effect that the pressure loss increases when the molded product is filled in the adsorption tower. On the other hand, when the particles exceeding 1.7 mm exceed 10% of the whole grains, the liquid contact surface area is reduced, so that the adsorption performance is significantly lowered.
  • the whole grains have a particle size of 0.2 mm or more and 1.7 mm or less. Further, it is preferable that the particle size of 90% or more of the whole grain is 0.3 mm or more and 1.0 mm or less. These are the particle sizes that are assumed to be filled in the adsorption tower of the actual contaminated water treatment facility of a nuclear power plant.
  • the layered manganese oxide molded product of the present invention is characterized by having a bulk density of 0.9 g / cm 3 or more. 1.0 g / cm 3 or more is preferable. If the bulk density is less than 0.9 g / cm 3 , the weight of the molded product that can be filled in a constant volume is reduced, so that the adsorption capacity is reduced.
  • the layered manganese oxide molded product of the present invention contains at least a metal salt aqueous solution containing manganese, an alkali metal aqueous solution and an oxidizing agent having an alkali metal / manganese molar ratio of 2 or more and 10 or less, and the oxidation-reduction potential of the reaction solution is based on a saturated caromel electrode.
  • step 2 in which the precipitated substance is thermally cured at 40 ° C. or higher and 200 ° C. or lower after filtration.
  • the manganese-containing metal salt aqueous solution used in step 1 can be prepared by dissolving the manganese-containing metal salt in water.
  • the metal salt containing manganese include water-soluble manganese sulfate (II), manganese chloride (II), manganese nitrate (II), manganese acetate (II), and the like, and even if it is anhydrous, it is a hydrate. There may be.
  • manganese sulfate (II) is most suitable in consideration of waste liquid treatment, corrosiveness, and raw material cost. Further, manganese and other metal ions can be mixed and used as long as the formation of the layered manganese oxide is not inhibited.
  • the alkaline earth metal concentration in the metal salt aqueous solution is low, and the total alkaline earth metal concentration must be less than 1500 ppm.
  • the total alkaline earth metal concentration is preferably less than 1000 ppm, more preferably 500 ppm, and even more preferably less than 100 ppm.
  • the total concentration (metal concentration) of all metals such as manganese in the metal salt aqueous solution is arbitrary, but the metal concentration affects productivity, so 1.0 mol / L or more is preferable, and 2.0 mol / L or more is preferable. More preferred.
  • the alkali metal aqueous solution used in step 1 can be prepared by dissolving the alkali metal compound in water.
  • the alkali metal compound for example, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, an alkali metal carbonate such as sodium carbonate or potassium carbonate, or the like is suitable from the viewpoint of water solubility, cost, and pH adjustment.
  • the alkali metal concentration of the alkali metal aqueous solution can be exemplified as 1 mol / L or more from the viewpoint of productivity.
  • the alkali metal / manganese molar ratio is 2 or more and 10 or less.
  • manganese tetraoxide (Mn 3 O 4 ) is by-produced, and if it exceeds 10, manganese tetraoxide (Mn 3 O 4 ) is by-produced. From the viewpoint of strontium adsorption performance, it is preferably 3 or more and 8 or less.
  • Examples of the oxidizing agent used in step 1 include hydrogen peroxide, oxygen, air, and peroxodisulfate.
  • Examples of the peroxodisulfate include sodium peroxodisulfate, potassium peroxodisulfate, and ammonium peroxodisulfate.
  • hydrogen peroxide solution, oxygen or air is preferable in terms of ease of raw material procurement and cost. Further economically, oxygen or air is preferable, and air is more preferable. Gases such as air and oxygen are added by bubbling in a mixed aqueous solution using a bubbler or the like.
  • a mixed aqueous solution is obtained by adjusting the redox potential of the reaction solution in step 1 to ⁇ 0.2 V or more and 0.6 V or less based on the saturated calomel electrode, and the layered manganese oxide of the present invention is precipitated from the mixed aqueous solution.
  • the redox potential range is exceeded, Mn 3 O 4 and permanganate are produced as by-products. Since Mn 3 O 4 is inactive for strontium adsorption, its formation leads to a decrease in strontium adsorption performance. Similarly, if the redox potential range is exceeded, the strength of the layered manganese oxide molded product of the present invention decreases.
  • a more preferable redox potential range is ⁇ 0.1 V or more and 0.5 V or less based on the saturated calomel electrode.
  • the redox potential of the reaction solution is a value based on a general standard hydrogen electrode, and can be obtained by a commercially available redox potential meter.
  • the redox potential can be controlled by the supply amount of the oxidizing agent and the reaction temperature.
  • the temperature at which the aqueous metal salt solution containing manganese, the aqueous alkali metal solution and the oxidizing agent are mixed is 0 ° C. or higher and 100 ° C. or lower. If the mixing temperature is less than 0 ° C., the oxidation reaction may not proceed and the reaction solution may solidify, and if it exceeds 100 ° C., particle growth proceeds and the desired dense aggregate cannot be obtained. Since the oxidation reaction is likely to proceed and the layered manganese oxide is more likely to be precipitated, the temperature is preferably 40 ° C. or higher and 80 ° C. or lower.
  • the metal salt aqueous solution containing manganese, the alkali metal aqueous solution and the oxidizing agent are mixed in step 1, either a batch type or a continuous type reaction may be used.
  • the pH at the end of mixing is preferably 7 or more and 14 or less, and the pH and the oxidation-reduction potential of the reaction solution can be appropriately adjusted by controlling the charging rate of either a metal salt containing manganese or an aqueous alkali metal solution.
  • the method of adding the metal aqueous solution and the alkali metal aqueous solution it is preferable to keep the alkali metal / manganese molar ratio constant and then drop them at a constant velocity at the same time because a dense molded body having high strength and adsorption performance can be obtained.
  • at least the required power for stirring at the time of mixing the metal salt aqueous solution containing manganese, the alkali metal aqueous solution and the oxidizing agent is required to be 0.5 kW / m 3 or more.
  • stirring power is insufficient such that the required power for stirring is less than 0.5 kW / m 3 , a by-product phase is generated and the desired dense aggregate cannot be obtained.
  • the solid content concentration in the slurry obtained by mixing the raw material liquid in step 1 needs to be 1 wt% or more and 5 wt% or less. A high concentration is desirable to ensure productivity, but if it exceeds 5 wt%, a dense aggregate tends not to be obtained. At this time, in order to achieve both production efficiency and precision, 3 wt% or more and 4 wt% or less are preferable.
  • step 2 the method for filtering the layered manganese oxide precipitated in step 1 is not particularly limited as long as solid-liquid separation is possible.
  • a belt filter, a filter press, a pressure filtration device, an ultrafiltration device and the like can be used.
  • the layered manganese oxide may be washed during filtration.
  • the temperature at which the layered manganese oxide is thermoset to produce the layered manganese oxide molded product of the present invention is 40 ° C. or higher from the viewpoint of shape retention of the layered manganese oxide molded product of the present invention. It is carried out at 200 ° C. or lower, and is preferably carried out at 40 ° C. or higher and 160 ° C. or lower.
  • the thermosetting treatment may also serve as a treatment for drying the filtered cake of the layered manganese oxide obtained by filtration.
  • thermosetting treatment is performed after the filtered cake is in its original shape or is appropriately crushed or molded.
  • the time of the thermosetting treatment is appropriately determined according to the progress of curing. As described above, by setting the drying conditions to be mild, a granular molded product which is a high-hardness and high-density agglomerate can be obtained. Therefore, the thermosetting conditions (drying shape, temperature, time of the filtered cake) are appropriately set. Achieved by controlling. Rotary drying and flash drying are not suitable because they tend to form particles with a particle size of less than 0.2 mm.
  • 90% or more of the total granules have a particle size of 0.2 mm or more by thermosetting the filtered cake and then crushing and classifying the cake as necessary. It is performed so that the particles are 0.7 mm or less.
  • the crushing method is not particularly limited, and general crushers such as cone crushers, crusher type crushers such as roll crushers, cutter mills, stamp mills, ring mills, roller mills, jet mills, hammer mills, rotary mills (ball mills), It can be performed by a mill type crusher such as a vibration mill.
  • either dry classification or wet classification can be used, and a hydraulic classification machine, a sedimentation classification machine, a mechanical classification machine, an air flow classification machine, a gravity classification machine, a cyclone type classification machine, a sieving type classification machine, etc. can be appropriately used.
  • a hydraulic classification machine a sedimentation classification machine, a mechanical classification machine, an air flow classification machine, a gravity classification machine, a cyclone type classification machine, a sieving type classification machine, etc.
  • the layered manganese oxide molded product of the present invention can be used, for example, for adsorbing strontium adsorbents or other heavy metals.
  • strontium adsorbent As a strontium adsorbent, it is useful for selectively adsorbing strontium from a treatment liquid in which a large amount of coexisting ions are present.
  • the present invention has the following configuration.
  • A is an alkali metal containing at least sodium and potassium, 0.4 ⁇ x ⁇ 0.6, and is assigned as a hexagon in a powder X-ray diffraction experiment.
  • a mixed aqueous solution is obtained by mixing at -0.2 V or more and 0.6 V or less, a temperature of 0 ° C. or more and 100 ° C. or less, and a required stirring power per unit volume of 0.5 kW / m 3 or more, and in the mixed aqueous solution.
  • the solid content concentration of the slurry is precipitated at 1 wt% or more and 5 wt% or less, and then the precipitated substance is thermally cured at 40 ° C. or higher and 200 ° C. or lower after filtration.
  • the precipitated substance to be precipitated in the mixed aqueous solution is bucelite having an interlayer distance of 9 angstroms or more and 10 angstroms or less, and the precipitated substance has an interlayer distance of 7.0 angstroms or more and 7.3 angstroms or less in the heat curing process.
  • the elemental composition analysis of the obtained sample was performed by inductively coupled plasma emission spectrometry (ICP method). That is, a measurement solution was prepared by dissolving the sample powder under pressure with hydrogen peroxide solution and hydrofluoric acid. The elemental composition of the obtained sample was analyzed by measuring the obtained measurement solution using an inductively coupled plasma emission spectrometer (trade name: OPTIMA3000DV, manufactured by PERKIN ELMER).
  • ICP method inductively coupled plasma emission spectrometry
  • the crushing strength of the sample was measured using a microcompression tester (trade name: MCT-510, manufactured by Shimadzu Corporation). The crushing strength was measured by applying a load to the sample with a diamond platen. Randomly taken out molded granules were placed on a sample table, the diamond platen was automatically lowered, and the test force when the particles collapsed was taken as the crushing strength. The crushing strength was the test force when the displacement of the diamond platen under load was the largest. From the observation with a microscope, the displacement that seems to be the fine movement of the particles before the collapse was excluded. ) This measurement was repeated 25 times, and the average value was taken as the crushing strength of the molded product.
  • simulated seawater A Ca 2+ : 5ppm, Mg 2+ : 2ppm, Sr 2+ : 5ppm, Cs + : 1ppm, pH 7 object to be treated A
  • NaCl 0.3%
  • pH 7 to be treated liquid B (hereinafter referred to as “simulated seawater B”) was prepared, and further, the liquid to be treated A was prepared with a 1N-NaOH aqueous solution.
  • simulated seawater C a pH 12 object to be treated C having NaCl: 0.3%, Ca 2+ : 5 ppm, Mg 2+ : 0 ppm, Sr 2+ : 5 ppm, Cs +: 1 ppm.
  • treatment liquids A to C treated simulated seawater
  • the strontium concentration in the treatment liquid was measured by inductively coupled plasma emission spectrometry (ICP method).
  • the strontium concentration was determined by measuring the treatment liquid using a general inductively coupled plasma emission spectrometer (trade name: OPTIMA3000DV, manufactured by PERKIN ELMER).
  • the strontium concentration of the simulated seawater before the adsorption test is C 0 (mg / L)
  • the strontium concentration of the treatment solution is C (mg / L)
  • C / C 0 is the unit from the start of the simulated seawater flow to the sampling time.
  • VV total simulated seawater flow volume per adsorbent volume
  • ⁇ Measuring method of particle weight fraction corresponding to particle size of 0.2 mm or more and 1.7 mm or less The sample was passed through a metal sieve with an opening of 1.7 mm (10 mesh) and an opening of 0.21 mm (70 mesh).
  • the weight fraction of the granular material corresponding to the particle size of 0.2 mm to 1.7 mm is the weight A of the granular material above the sieve with a mesh opening of 1.7 mm and the weight A under the sieve with a mesh opening of 0.21 mm, and the weight B of the whole granular material. It was calculated by the following formula.
  • Granular material weight fraction (%) corresponding to a particle size of 0.2 mm or more and 1.7 mm or less 100 ⁇ (BA) / B ⁇ Calculation method of required power for stirring>
  • the required stirring power per unit volume was calculated by the following formula.
  • Np Np ⁇ ⁇ ⁇ n 3 ⁇ d 5
  • Pv P / V (P: Power required for stirring [W], Pv: Power required for stirring per volume [kW / m 3 ], ⁇ : Density [kg / m 3 ], n: Rotation speed [rps], d: Blade span [m] , Np: power number [-], V: volume [L])
  • Np power number
  • 10 L reaction tank, 1.1 L reaction tank for paddle blade, and 1.8 for paddle blade were used.
  • ⁇ density is 1.22 g / cc
  • d blade span is 10 L reaction tank
  • paddle blade is 128 mm
  • 1 L reaction tank paddle blade is 80 mm
  • V volume is 10 L reaction tank ⁇ 5 L ( Example 3) 1L reaction vessel ⁇ 0.7L (Examples 1 and 4 and Comparative Examples 2 and 3) and 0.3L (Comparative Example 4) were used.
  • Example 1 300 g of pure water was placed in a reaction vessel having an internal volume of 1 L, and the temperature was raised and maintained at 40 ° C. Separately, manganese sulfate was dissolved in pure water to prepare a metal salt aqueous solution containing 0.82 mol / L manganese sulfate.
  • the alkaline earth concentration of the metal salt aqueous solution was Ca 10 ppm, Mg 7 ppm, and other alkaline earth metals were below the detection limit.
  • the metal salt aqueous solution was added to the reaction vessel at a supply rate of 10 g / min. At the same time, 35% hydrogen peroxide solution was added as an oxidizing agent into the reaction vessel at a supply rate of 5.4 g / min.
  • a 4-blade paddle blade having an outer diameter of 80 mm was used and rotated at 600 ppm.
  • the power required for stirring at that time was 10 kW / m 3 .
  • a 5 mol / L potassium hydroxide aqueous solution (alkali metal aqueous solution) was continuously added for 30 minutes so that the redox potential was ⁇ 0.055 V based on the saturated calomel electrode.
  • the K / Mn molar ratio was 4.7 when the metal salt aqueous solution and the 35% hydrogen peroxide solution were supplied.
  • the obtained slurry is filtered, washed with pure water, and then the washed wet cake is dried at 60 ° C. for 5 hours and thermoset to cause agglomerates of layered manganese oxide (K 0.34 MnO 2).
  • K 0.34 MnO 2 layered manganese oxide
  • the lumpy agglomerates were crushed by tapping with an alumina mortar and pestle. After that, it is passed through a mesh with a mesh opening of 0.6 mm, and what remains on the mesh with a mesh opening of 0.3 mm is collected to classify the product into 0.3 to 0.6 mm to obtain a layered manganese oxide molded product. It was.
  • the obtained layered manganese oxide molded product was found to have a layered crystal structure by measurement of powder X-ray diffraction, and was consistent with a diffraction pattern derived from a burnesite-type crystal structure in which potassium ions were present between layers.
  • the interlayer distance was 7.12 angstroms, and the FWHM of the 001 peak when it was assigned to the hexagonal crystal was 1.500 °.
  • the K / Mn molar ratio measured by elemental composition was 0.34.
  • the bulk density of the obtained layered manganese oxide molded product was 1.18 g / cm 3 , the crushing strength was 2339 mN, and the degree of agitation wear was 2.15% by weight. There was no change in the shape of the layered manganese oxide molded product before and after the measurement of the degree of stirring wear.
  • the silicon, aluminum, titanium and zirconium concentrations of the molded product were below the detection limit, and the carbon concentration was below the detection limit (3000 ppm or less).
  • Table 1 shows the measurement results of the layered manganese oxide molded product. Further, the powder X-ray diffraction pattern of the layered manganese oxide is shown in FIG. 1, and the scanning electron microscope image (SEM image) of the layered manganese oxide is shown in FIG.
  • Example 2 Manganese nitrate hexahydrate (Kanto Chemical Co., Ltd., 98%), 52.83 g, is dissolved in a small amount of water, and a volumetric flask is used to increase the volume to 600 mL to 0.3 mol / L to produce manganese nitrate.
  • An aqueous manganese solution was prepared. 47.61 g of potassium hydroxide (KOH) was dissolved in a small amount of water, and 51.60 mL of hydrogen peroxide solution (H 2 O 2 , 35%) was added thereto (H 2 O 2 + KOH aqueous solution). It was prepared to 600 mL using a volumetric flask. At this time, the KOH concentration was 1.2 mol / L and the H 2 O 2 concentration was 1.0 mol / L.
  • KOH potassium hydroxide
  • a 600 mL aqueous manganese nitrate solution was transferred to a 2000 mL beaker, and 600 mL of an H 2 O 2 + KOH aqueous solution was slowly added thereto with stirring using a magnetic stirrer. After stirring for 10 minutes, the stirring is stopped and the mixture is allowed to stand for 1 hour, the obtained solid is filtered under reduced pressure using a filter paper, washed with 3000 mL of water, and dried in a dryer at 60 ° C. for 1 day. Heat-cured with. The dried product was a glossy lumpy aggregate, and the yield was 21.12 g.
  • the lumpy agglomerate was placed in an alumina mortar and crushed with a pestle.
  • the crushed pieces after crushing are opened, passed through a 0.6 mm mesh, and the residue remaining on the mesh with a mesh opening of 0.3 mm is collected to classify the crushed pieces into 0.3 to 0.6 mm and layered manganese oxide.
  • a molded product was obtained.
  • FIG. 3 shows the powder X-ray diffraction patterns of the wet sample A obtained after filtration and cleaning and the sample B thermoset at 60 ° C. for one day.
  • Sample A can be attributed to buserite with an interlayer distance of 9.37 angstroms
  • sample B can be attributed to burnesite with an interlayer distance of 7.09 angstroms.
  • the FWHM of the 001 peak was 1.212 °.
  • the precipitated substance is bucelite having an interlayer distance of 9 angstroms or more and less than 10 angstroms, and changes to burnesite having an interlayer distance of 7 angstroms in the heat curing process. It was confirmed that
  • the obtained layered manganese oxide molded product had a bulk density of 1.19 g / cm 3 , a crushing strength of 3426 mN, and a stirring wear degree of 2.87% by weight. There was no change in the shape of the layered manganese oxide molded product before and after the measurement of the degree of stirring wear.
  • the silicon, aluminum, titanium and zirconium concentrations of the molded product were below the detection limit, and the carbon concentration was below the detection limit (3000 ppm or less).
  • Table 1 shows the measurement results of the layered manganese oxide molded product. Further, a scanning electron microscope image (SEM image) of the layered manganese oxide is shown in FIG.
  • Example 3 2800 g of pure water was placed in a reaction vessel having an internal volume of 10 L, and the temperature was raised and maintained at 60 ° C. Separately, manganese sulfate was dissolved in pure water to prepare a metal salt aqueous solution containing 2.0 mol / L manganese sulfate.
  • the alkaline earth concentration of the metal salt aqueous solution was Ca 22 ppm, Mg 15 ppm, and other alkaline earth metals were below the detection limit.
  • the metal salt aqueous solution was added to the reaction vessel at a supply rate of 35 g / min. At the same time, 35% hydrogen peroxide solution was added into the reaction vessel as an oxidizing agent at a supply rate of 13 g / min.
  • the obtained slurry is filtered, washed with pure water, and then the washed wet cake is dried at 60 ° C. for 5 hours and thermoset to cause agglomerates of layered manganese oxide (K 0.35 MnO 2). I got something.
  • the lumpy agglomerates were crushed by tapping with an alumina mortar and pestle. After that, a mesh with a mesh opening of 0.6 mm is passed through, and what remains on the mesh with a mesh opening of 0.3 mm is collected to classify the mixture into 0.3 to 0.6 mm to obtain a layered manganese oxide molded product. It was.
  • the obtained layered manganese oxide molded product contained a slight by-product phase by powder X-ray diffraction measurement, but it was found that the main phase was a burnesite-type oxide in which potassium ions were present between layers.
  • the interlayer distance was 7.09 angstroms, and the FWHM of the 001 peak when it was assigned to the hexagonal crystal was 1.167 °.
  • the K / Mn molar ratio measured by elemental composition was 0.35.
  • the bulk density of the obtained layered manganese oxide molded product was 1.39 g / cm 3 , the crushing strength was 1591 mN, and the degree of agitation wear was 4.02% by weight. There was no change in the shape of the layered manganese oxide molded product before and after the measurement of the degree of stirring wear.
  • the silicon, aluminum, titanium and zirconium concentrations of the molded product were below the detection limit, and the carbon concentration was below the detection limit (3000 ppm or less).
  • Table 1 shows the measurement results of the layered manganese oxide molded product.
  • the powder X-ray diffraction pattern of the layered manganese oxide is shown in FIG. 5, and the scanning electron microscope image (SEM image) of the layered manganese oxide is shown in FIG.
  • Example 4 800 g of pure water was placed in a reaction vessel having an internal volume of 1 L having an extraction port at the top of the vessel, and the temperature was raised and maintained at 60 ° C.
  • manganese sulfate was dissolved in pure water to prepare a metal salt aqueous solution containing 0.90 mol / L manganese sulfate.
  • the metal salt aqueous solution was added to the reaction vessel at a supply rate of 10 g / min.
  • a 2.3 mol / L potassium hydroxide aqueous solution (alkali metal aqueous solution) was prepared and added to the reaction vessel at 19 g / min.
  • a 10% aqueous solution of sodium peroxodisulfate was prepared as an oxidizing agent and added to the reaction vessel at a supply rate of 18 g / min at the same time as the aqueous metal salt solution and the aqueous alkali metal solution.
  • the stirring power per volume at the time of mixing was 10 kW / m 3 .
  • the above operation was continuously performed for 4 hours.
  • the slurry that flowed out was sampled every 40 minutes.
  • the solid content concentration of the slurry that flowed out from 200 minutes to 240 minutes after the start of the experiment was 1.8 wt%.
  • layered manganese oxide Na 0.25 K 0.23 MnO 2
  • the lumpy agglomerates were crushed by tapping with an alumina mortar and pestle. After that, a mesh with a mesh opening of 0.6 mm is passed through, and what remains on the mesh with a mesh opening of 0.3 mm is collected to classify the mixture into 0.3 to 0.6 mm to obtain a layered manganese oxide molded product. It was.
  • the obtained layered manganese oxide molded product was found to have a layered crystal structure by measurement of powder X-ray diffraction, and was consistent with a diffraction pattern derived from a burnesite-type crystal structure in which potassium ions were present between layers.
  • the interlayer distance was 7.18 angstroms, and the FWHM of the 001 peak when it was assigned to the hexagonal crystal was 3.210 °.
  • the Na / Mn molar ratio was 0.25 and the K / Mn molar ratio was 0.23 as measured by the element composition.
  • the bulk density of the obtained layered manganese oxide molded product was 1.33 g / cm 3 , the crushing strength was 2069 mN, and the degree of agitation wear was 0.05% by weight. There was no change in the shape of the layered manganese oxide molded product before and after the measurement of the degree of stirring wear.
  • the silicon, aluminum, titanium and zirconium concentrations of the molded product were below the detection limit, and the carbon concentration was below the detection limit (3000 ppm or less).
  • Table 1 shows the measurement results of the layered manganese oxide molded product.
  • the powder X-ray diffraction pattern of the layered manganese oxide is shown in FIG. 7, and the scanning electron microscope image (SEM image) of the layered manganese oxide is shown in FIG.
  • the obtained potassium-type layered manganese oxide was found to have a layered crystal structure by measurement of powder X-ray diffraction, and was consistent with the diffraction pattern derived from the burnesite-type crystal structure in which potassium ions were present between layers.
  • the interlayer distance was 7.14 angstroms
  • the FWHM of the 001 peak when assigned to hexagonal crystals was 0.577 °
  • the K / Mn molar ratio determined from the elemental composition was 0.307.
  • Potassium-type layered manganese oxide 100 parts by weight Silica in silica sol: 16 parts by weight Water: 36 parts by weight CMC: 5 parts by weight Silica sol as an inorganic binder has a sol concentration of 48% by weight and average particles of silica particles in the sol.
  • a silica sol (trade name: Snowtex 50-T, manufactured by Nissan Chemical Industries, Ltd.) having a diameter average sol particle size of 0.02 ⁇ m was used.
  • CMC (trade name: Cellogen WS-D, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was used as a molding aid.
  • the obtained mixture was mixed with a Henschel mixer for 20 minutes and then extruded to obtain a cylindrical molded body having a diameter of 1.5 mm.
  • the obtained molded product was fired at 500 ° C. for 3 hours under an air flow of 25 L / min, crushed, passed through a mesh having an opening of 0.6 mm, and remained on a mesh having an opening of 0.3 mm. Was collected and classified into 0.3 to 0.6 mm to obtain a layered manganese oxide molded product.
  • the obtained layered manganese oxide molded product had a bulk density of 0.771 g / cm 3 , a crushing strength of 483 mN, and a stirring wear degree of 31.0% by weight. There was no change in the shape of the layered manganese oxide molded product before and after the measurement of the degree of stirring wear.
  • the concentrations of silicon, aluminum, titanium and zirconium in the molded product were 6.4 wt% of silicon.
  • the carbon concentration was below the detection limit (3000 ppm or less).
  • Table 1 shows the measurement results of the layered manganese oxide molded product. Further, the powder X-ray diffraction pattern of the layered manganese oxide is shown in FIG. 9, and the scanning electron microscope image (SEM image) of the layered manganese oxide is shown in FIG.
  • Comparative Example 2 300 g of pure water was placed in a reaction vessel having an internal volume of 1 L, and the temperature was raised and maintained at 40 ° C. An aqueous metal salt solution containing manganese sulfate (manganese sulfate concentration 0.82 mol / L) containing an alkaline earth metal component for industrial use was used. The alkaline earth metal concentration in the metal salt aqueous solution was Ca 500 ppm, Mg 1400 ppm, and other alkaline earth metals were below the detection limit. Synthesis was carried out in the same manner as in Example 1 except that the alkaline earth metal concentrations of the manganese sulfate aqueous solution were different.
  • FIG. 11 shows a powder X-ray diffraction pattern of the dried sample after filtration and cleaning. Since almost no low-angle 001 peak showing a layered structure was observed, it was found that the manganese oxide was not a layered manganese oxide.
  • Table 1 shows the measurement results of the manganese oxide molded product.
  • Comparative Example 3 The synthesis was carried out in the same manner as in Example 1 except that the rotation speed of the stirring blade was reduced to 100 rpm and the required power for stirring was set to 0.4 kW / m 3.
  • FIG. 12 shows a powder X-ray diffraction pattern of the dried sample after filtration and cleaning.
  • Other birnessite type layered manganese oxide present potassium ions between layers, because the peak of MnOOH and Mn 3 O 4 is strongly observed, the sample was confirmed to be a mixture of these phases.
  • Table 1 shows the measurement results of the layered manganese oxide.
  • Comparative Example 4 100 g of pure water was placed in a reaction vessel having an internal volume of 1 L, and the temperature was raised and maintained at 40 ° C. Separately, manganese sulfate was dissolved in pure water to prepare a metal salt aqueous solution containing 2.0 mol / L manganese sulfate. The metal salt aqueous solution was added to the reaction vessel at a supply rate of 5 g / min.
  • a 10 mol / L potassium hydroxide aqueous solution (alkali metal aqueous solution) was added into the reaction vessel at a supply rate of 3.3 g / min, and a 35% hydrogen peroxide solution as an oxidizing agent was added at a supply rate of 1.6 g / min.
  • the K / Mn molar ratio was 3.0 when the metal salt aqueous solution and the 35% hydrogen peroxide solution were supplied.
  • the stirring power per volume at the time of mixing was 23 kW / m 3 .
  • a slurry in which layered manganese oxide was precipitated was obtained by the above operation.
  • the solid content concentration of the slurry was 6.2 wt%.
  • the obtained slurry is filtered, washed with pure water, and then the washed wet cake is dried at 60 ° C. for 5 hours and thermoset to cause agglomerates of layered manganese oxide (K 0.29 MnO 2).
  • K 0.29 MnO 2 layered manganese oxide
  • the lumpy agglomerates were crushed by tapping with an alumina mortar and pestle. After that, a mesh with a mesh opening of 0.6 mm is passed through, and what remains on the mesh with a mesh opening of 0.3 mm is collected to classify the mixture into 0.3 to 0.6 mm to obtain a layered manganese oxide molded product. It was.
  • the obtained layered manganese oxide molded product was found to have a layered crystal structure by measurement of powder X-ray diffraction, and was consistent with a diffraction pattern derived from a burnesite-type crystal structure in which potassium ions were present between layers.
  • the interlayer distance was 7.12 angstroms, and the FWHM of the 001 peak when it was assigned to the hexagonal crystal was 1.440 °.
  • the K / Mn molar ratio measured by elemental composition was 0.34.
  • Table 1 shows the measurement results of the layered manganese oxide molded product.
  • the layered manganese oxide molded product of the present invention can be used as an adsorbent for strontium.
  • it can be used as an adsorbent for selectively adsorbing strontium ions from treated water containing a large amount of coexisting cations, such as seawater containing radionuclides derived from a uranium fission reactor.

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Abstract

The present invention provides a layered manganese oxide molded body that exhibits high performance for selective removal of strontium from a liquid which has treated contaminated water from a nuclear power plant, and in which there are coexisting ions. A layered manganese oxide molded body which is configured from a layered manganese oxide that contains at least an alkali metal and manganese, wherein: the crushing strength as determined by a micro compression testing machine is from 1,000 mN to 5,000 mN; an inorganic binder and an organic component are not substantially contained; 90% or more particles among all particles contained therein have a particle diameter from 0.2 mm to 1.7 mm; and the bulk density is 0.9 g/cm3 or more. A method for producing this layered manganese oxide molded body.

Description

層状マンガン酸化物成形体およびその製造方法Layered manganese oxide molded product and its manufacturing method
　本発明は、層状マンガン酸化物成形体およびその製造方法に関する。 The present invention relates to a layered manganese oxide molded product and a method for producing the same.
　水溶液から有害または有用なイオンを、固相吸着材を用いて吸着分離する操作は、高コストの水溶液の濃縮を伴わないため、分離技術として重要である。特に、ストロンチウムイオンの吸着は、ストロンチウムがウラン核***型原子力発電における核***生成物中の生成量が多く、かつストロンチウム濃度の排水基準値が低いことから、とりわけ重要である。ストロンチウムの選択吸着分離が可能な材料として、マンガン酸化物が従来広く知られている。 The operation of adsorbing and separating harmful or useful ions from an aqueous solution using a solid phase adsorbent is important as a separation technique because it does not involve concentration of a high-cost aqueous solution. In particular, the adsorption of strontium ions is particularly important because strontium is produced in a large amount in fission products in uranium fission-type nuclear power generation and the strontium concentration has a low wastewater standard value. Manganese oxide has been widely known as a material capable of selectively adsorbing and separating strontium.
　海水中のストロンチウムイオンの吸着剤として、マンガン原料とナトリウム原料を混合し焼成する固相反応法で合成した、層間内にナトリウムイオンを有する層状マンガン酸化物が特許文献１に開示されている。 Patent Document 1 discloses a layered manganese oxide having sodium ions in the layers, which is synthesized by a solid phase reaction method in which a manganese raw material and a sodium raw material are mixed and fired as an adsorbent for strontium ions in seawater.
　また、同じく海水中のストロンチウムイオンの吸着剤として、マンガン原料とカリウム原料を混合し焼成する固相反応法で合成した、層間内にカリウムイオンを有する層状マンガン酸化物が特許文献２に開示されている。 Further, Patent Document 2 discloses a layered manganese oxide having potassium ions in the layers, which is also synthesized by a solid-phase reaction method in which a manganese raw material and a potassium raw material are mixed and fired as an adsorbent for strontium ions in seawater. There is.
　さらに、ストロンチウムを含む放射性核種の吸着剤として、バーネサイト型の層状マンガン酸化物が非特許文献１に開示されている。本物質は水酸化マンガンのゾルと過マンガン酸マグネシウムとを反応させ高アルカリ条件下（ｐＨ１３．７）で７日間熟成することで得られる。 Further, as an adsorbent for radionuclides containing strontium, a burnesite-type layered manganese oxide is disclosed in Non-Patent Document 1. This substance is obtained by reacting a manganese hydroxide sol with magnesium permanganate and aging under high alkaline conditions (pH 13.7) for 7 days.
　しかし、何れの文献も粉末での吸着性能に関する記載に留まり、成形体としての性能への言及は一切ない。実際の原子力発電所汚染水処理設備での吸着剤の使用形態を考えた場合、圧力損失が高くかつ廃棄処理が煩雑である粉末形態である必然性はなく、むしろ不都合である。この目的には、吸着塔に充填可能でありかつ圧力損失が低く、廃棄処理が簡便な成形体として使用されることが想定される。このような成形体についてはストロンチウム吸着性能のみならず、乾燥状態もしくは海水通水時の機械的強度、保形性など副次的機能も要求されることは言うまでもない。 However, all the documents only describe the adsorption performance of powder, and there is no mention of the performance as a molded product. Considering the usage pattern of the adsorbent in the actual contaminated water treatment facility of a nuclear power plant, it is not necessarily in the powder form that the pressure loss is high and the disposal treatment is complicated, which is rather inconvenient. For this purpose, it is assumed that the adsorption tower can be filled, the pressure loss is low, and the molded product is easy to dispose of. Needless to say, such a molded product is required to have secondary functions such as mechanical strength and shape retention in a dry state or when seawater is passed, as well as strontium adsorption performance.
ＷＯ２０１７／０８６０５６Ａ１WO2017 / 086056A1 ＷＯ２０１８／１１０６１５Ａ１WO2018 / 110615A1
　従来の固相反応法で合成した層状マンガン酸化物は、それ自体の凝集による成形体の作製は困難である。したがって、成形体として使用用途に好適な強度を実現するには無機結合剤の添加使用が不可欠であった。しかし、無機結合剤はストロンチウム吸着には寄与しないため、その使用は吸着性能低下につながる。また、吸着表面を無機結合剤で被覆、閉塞することで層状マンガン酸化物の吸着利用率が低下する。加えて、無機結合剤と層状マンガン酸化物との混錬物につき、押し出し成型などを利用する場合、有機化合物で増粘させる追加工程が必要な場合がある。このような有機化合物で処理した成形体を原子力発電所汚染水処理に使用した場合、放射線による変質で成形体の機械的強度低下は免れない。また、熱処理して有機化合物を酸化、燃焼させた場合も、層状マンガン酸化物が還元、分解変質する懸念がある。 It is difficult to prepare a molded product by agglutination of the layered manganese oxide synthesized by the conventional solid-phase reaction method. Therefore, it was indispensable to add and use an inorganic binder in order to realize the strength suitable for the intended use as a molded product. However, since the inorganic binder does not contribute to the adsorption of strontium, its use leads to a decrease in adsorption performance. Further, by coating and closing the adsorption surface with an inorganic binder, the adsorption utilization rate of the layered manganese oxide is reduced. In addition, when the kneaded product of the inorganic binder and the layered manganese oxide is extruded or the like, an additional step of thickening with an organic compound may be required. When a molded product treated with such an organic compound is used for treatment of contaminated water at a nuclear power plant, it is inevitable that the mechanical strength of the molded product will decrease due to alteration due to radiation. Further, even when the organic compound is oxidized and burned by heat treatment, there is a concern that the layered manganese oxide is reduced or decomposed and deteriorated.
　また、固相反応法で合成した層状マンガン酸化物粉末と無機結合剤より調製した成形体は、かさ密度が低い場合が多い。一定体積の吸着塔への層状マンガン酸化物成形体の充填については、かさ密度が高い方がより多くの重量が充填可能となるため、結果的にストロンチウム吸着容量が増大する。この点でも、吸着材以外の結合剤などの成分を含まず、かさ密度が高いことは有利に働く。 In addition, the bulk density of the molded product prepared from the layered manganese oxide powder synthesized by the solid phase reaction method and the inorganic binder is often low. Regarding the filling of the layered manganese oxide compact into a fixed volume adsorption tower, the higher the bulk density, the more weight can be filled, and as a result, the strontium adsorption capacity increases. In this respect as well, it is advantageous that the bulk density is high without containing components such as a binder other than the adsorbent.
　さらには、固相反応法で合成した層状マンガン酸化物成形体については、通水時の保形性が乏しい。保形性に乏しい場合、微粉化して吸着塔流路を閉塞する、あるいは吸着塔から層状マンガン酸化物成形体を取り出す際、泥状になり取扱いが困難になる不都合がある。このため、原子力発電所汚染水処理に固相反応法で合成した層状マンガン酸化物成形体を用いることは、放射性の成形体の廃棄に際し、大きな問題となることが想定される。 Furthermore, the layered manganese oxide molded product synthesized by the solid-phase reaction method has poor shape retention during water flow. If the shape retention is poor, there is a disadvantage that the layered manganese oxide molded product becomes muddy and difficult to handle when it is pulverized to block the flow path of the adsorption tower or when the layered manganese oxide molded product is taken out from the adsorption tower. Therefore, it is expected that the use of a layered manganese oxide molded product synthesized by the solid-phase reaction method for the treatment of contaminated water at a nuclear power plant will cause a big problem when disposing of the radioactive molded product.
　したがって、層状マンガン酸化物の含有率を極力上げ、無機結合剤および有機物を含有しない、ストロンチウム吸着性能と機械的強度、保形性を満足する成形体とその製造方法の開発が急務であった。 Therefore, there was an urgent need to develop a molded product and its manufacturing method that satisfy the strontium adsorption performance, mechanical strength, and shape retention without containing inorganic binders and organic substances by increasing the content of layered manganese oxide as much as possible.
　本発明はこれらの課題を解決するものであり、十分なストロンチウム吸着性能と機械的強度、保形性を同時に支障なく成立させる層状マンガン酸化物成形体を提供するものである。 The present invention solves these problems and provides a layered manganese oxide molded product that simultaneously establishes sufficient strontium adsorption performance, mechanical strength, and shape retention without any trouble.
　さらに、特許文献、非特許文献に示された層状マンガン酸化物を成形体として使用する場合は、原料を混合、焼成する固相合成法、または過マンガン酸塩とマンガン塩とを水溶液中で反応させる湿式合成法で層状マンガン酸化物粉末を得た後、無機結合剤、有機物からなる増粘剤とを加え混錬した後、押し出し成型機を使用してヌードル状に成形、乾燥した後、破砕するといった煩雑な製造工程が必要であった。 Further, when the layered manganate oxide shown in patent documents and non-patent documents is used as a molded product, a solid phase synthesis method in which raw materials are mixed and calcined, or a reaction between a permanganate and a manganese salt in an aqueous solution is performed. After obtaining a layered manganese oxide powder by a wet synthesis method, an inorganic binder and a thickener composed of an organic substance are added and kneaded, then molded into a noodle shape using an extrusion molding machine, dried, and then crushed. A complicated manufacturing process was required.
　本発明はこの課題を解決するものであり、本発明の層状マンガン酸化物成形体は、湿式反応後、ろ過、乾燥、破砕といった簡便な工程で成形体を作製可能である。 The present invention solves this problem, and the layered manganese oxide molded product of the present invention can be produced by a simple process such as filtration, drying, and crushing after a wet reaction.
　本発明者は強度、保形性およびストロンチウム吸着性能に優れる層状マンガン酸化物成形体およびその製造方法について鋭意検討した結果、強度、保形性と吸着性能をいずれも高いレベルで満足することを見いだし、本発明を完成するに至った。すなわち、本発明は、以下の構成を備えている。 As a result of diligent studies on a layered manganese oxide molded product having excellent strength, shape retention and strontium adsorption performance and a method for producing the same, the present inventor has found that the strength, shape retention and adsorption performance are all satisfied at a high level. , The present invention has been completed. That is, the present invention has the following configurations.
　すなわち、本発明の一態様に係る層状マンガン酸化物成形体は、少なくともアルカリ金属とマンガンとを含む層状マンガン酸化物から構成されており、微小圧縮試験機による測定で１０００ｍＮ以上５０００ｍＮ以下の圧壊強度を有し、無機結合剤および有機成分を含まず、全粒体の９０％以上が粒径０．２ｍｍ以上１．７ｍｍ以下の粒体であり、かさ密度０．９ｇ／ｃｍ３以上である。 That is, the layered manganese oxide molded product according to one aspect of the present invention is composed of a layered manganese oxide containing at least an alkali metal and manganese, and has a crushing strength of 1000 mN or more and 5000 mN or less as measured by a microcompression tester. It has, does not contain an inorganic binder and an organic component, and 90% or more of all the granules are granules having a particle size of 0.2 mm or more and 1.7 mm or less, and a bulk density of 0.9 g / cm 3 or more.
　本発明は、実際の原子力発電汚染水処理設備での使用形態を鑑みて、ストロンチウム吸着性能と機械的強度、保形性とを両立し、吸着に不活性な結合剤を含まない層状マンガン酸化物成形体を、簡便かつコストに優れる製造方法で提供可能である。 In view of the usage pattern in an actual nuclear power generation contaminated water treatment facility, the present invention has both strontium adsorption performance, mechanical strength, and shape retention, and is a layered manganese oxide that does not contain a binder that is inert to adsorption. The molded product can be provided by a simple and cost-effective manufacturing method.
実施例１の層状マンガン酸化物の粉末Ｘ線回折パターンである。It is a powder X-ray diffraction pattern of the layered manganese oxide of Example 1. 実施例１の層状マンガン酸化物成形体の走査電子顕微鏡像である。It is a scanning electron microscope image of the layered manganese oxide molded article of Example 1. 実施例２の層状マンガン酸化物（試料Ａおよび試料Ｂ）の粉末Ｘ線回折パターンである。It is a powder X-ray diffraction pattern of the layered manganese oxide (sample A and sample B) of Example 2. 実施例２の層状マンガン酸化物成形体の走査電子顕微鏡像である。It is a scanning electron microscope image of the layered manganese oxide molded article of Example 2. 実施例３の層状マンガン酸化物の粉末Ｘ線回折パターンである。It is a powder X-ray diffraction pattern of the layered manganese oxide of Example 3. 実施例３の層状マンガン酸化物成形体の走査電子顕微鏡像である。It is a scanning electron microscope image of the layered manganese oxide molded article of Example 3. 実施例４の層状マンガン酸化物の粉末Ｘ線回折パターンである。It is a powder X-ray diffraction pattern of the layered manganese oxide of Example 4. 実施例４の層状マンガン酸化物成形体の走査電子顕微鏡像である。It is a scanning electron microscope image of the layered manganese oxide molded article of Example 4. 比較例１の層状マンガン酸化物の粉末Ｘ線回折パターンである。It is a powder X-ray diffraction pattern of the layered manganese oxide of Comparative Example 1. 比較例１の層状マンガン酸化物成形体の走査電子顕微鏡像である。It is a scanning electron microscope image of the layered manganese oxide molded article of Comparative Example 1. 比較例２のマンガン酸化物成形体の粉末Ｘ線回折パターンである。It is a powder X-ray diffraction pattern of the manganese oxide molded article of Comparative Example 2. 比較例３の層状マンガン酸化物の粉末Ｘ線回折パターンである。It is a powder X-ray diffraction pattern of the layered manganese oxide of Comparative Example 3.
　以下、本発明について詳細に説明する。 Hereinafter, the present invention will be described in detail.
　本発明の層状マンガン酸化物成形体は、少なくともアルカリ金属とマンガンとを含む層状マンガン酸化物から構成される。中でも組成式ＡｘＭｎＯ２で表され、Ａはナトリウム及びカリウムから選ばれる少なくとも１種以上のアルカリ金属で表される層状Ａ－Ｍｎ酸化物が、乾燥および湿潤状態の結晶格子の大きさに差がなく、通水時の成形体崩壊を抑制可能である点で好ましい。アルカリ金属としては、ナトリウム及びカリウムのうち少なくとも１種が使用でき、両アルカリ金属の混合であってもよい。アルカリ金属は、本発明の層状マンガン酸化物成形体の乾燥、湿潤時の格子体積変化を抑制することができ、通水時の保形性を維持可能である点から、カリウムが好ましい。Ａはアルカリ金属であり、ｘは、Ａ／Ｍｎモル比を表し、すなわちｘの範囲は、０．２≦ｘ≦０．６で表すことができ、中でも０．３≦ｘ≦０．５の場合、本発明の層状マンガン酸化物成形体のストロンチウム吸着性能が高く、より好ましい。さらに、ナトリウムとカリウムの両方のアルカリ金属を含み、０．４≦ｘ≦０．６である層状マンガン酸化物成形体が、よりストロンチウム吸着性能が高いことを見出した。なお、酸素組成は空格子生成などにより若干の変動はあるが、整数値で２とみなせる。また、本発明の酸化マンガン成形体を構成する層状マンガン酸化物の層間、又は粒子間に水を含んでいてもよい。 The layered manganese oxide molded product of the present invention is composed of a layered manganese oxide containing at least an alkali metal and manganese. Among them, the layered A-Mn oxide represented by the composition formula A x MnO 2 and represented by at least one alkali metal selected from sodium and potassium differs in the size of the crystal lattice in the dry and wet states. It is preferable in that there is no such thing and it is possible to suppress the collapse of the molded body during water flow. As the alkali metal, at least one of sodium and potassium can be used, and a mixture of both alkali metals may be used. As the alkali metal, potassium is preferable because it can suppress changes in lattice volume during drying and wetting of the layered manganese oxide molded product of the present invention and can maintain shape retention during water flow. A is an alkali metal, x represents the A / Mn molar ratio, that is, the range of x can be represented by 0.2 ≦ x ≦ 0.6, among which 0.3 ≦ x ≦ 0.5. In this case, the layered manganese oxide molded product of the present invention has high strontium adsorption performance, which is more preferable. Furthermore, it was found that the layered manganese oxide molded product containing both alkali metals of sodium and potassium and having 0.4 ≦ x ≦ 0.6 has higher strontium adsorption performance. Although the oxygen composition varies slightly due to the formation of an empty lattice, it can be regarded as an integer value of 2. Further, water may be contained between the layers of the layered manganese oxide constituting the manganese oxide molded product of the present invention or between the particles.
　また、本発明の層状マンガン酸化物成形体の乾燥状態から湿潤状態への体積変化を抑制するためには、構成する層状マンガン酸化物の層間距離が７．０オングストローム以上７．３オングストローム以下であることが好ましい。この範囲を超えると、乾燥状態から湿潤状態への体積変化で成形体内部に歪を生じ、本発明の層状マンガン酸化物成形体が崩壊する可能性がある。なお、本発明の層状マンガン酸化物成形体の層間距離は粉末Ｘ線回折パターンの最低角回折ピークである、六方晶で帰属した場合の００１ピーク位置（角度）を面間隔（オングストローム）に換算することで得られる。 Further, in order to suppress the volume change from the dry state to the wet state of the layered manganese oxide molded product of the present invention, the interlayer distance between the constituent layered manganese oxides is 7.0 angstroms or more and 7.3 angstroms or less. Is preferable. If this range is exceeded, the inside of the molded product may be distorted due to the volume change from the dry state to the wet state, and the layered manganese oxide molded product of the present invention may collapse. The interlayer distance of the layered manganese oxide molded product of the present invention is the lowest angular diffraction peak of the powder X-ray diffraction pattern, and the 001 peak position (angle) when assigned by hexagonal crystals is converted into the plane spacing (angstrom). It can be obtained by.
　また、本発明の層状マンガン酸化物成形体の結晶性は低い方がストロンチウム吸着容量増大には有利となる。このため、粉末Ｘ線回折測定において、六方晶で帰属した場合の００１ピークの半値幅（ＦＷＨＭ）は大きいことが好ましい。具体的には、ＦＷＨＭが０．４°以上３．５°以下が好ましく、０．４°以上３．０°以下がより好ましく、０．７°以上２．２°以下がさらに好ましい。さらに、ナトリウムとカリウムの両方のアルカリ金属を含み、０．４≦ｘ≦０．６の場合には、粉末Ｘ線回折実験において六方晶で帰属した場合の００１ピークのＦＷＨＭが２．５°以上３．５°以下である層状マンガン酸化物成形体が、よりストロンチウム吸着性能が高いことを見出した。 Further, the lower the crystallinity of the layered manganese oxide molded product of the present invention, the more advantageous it is for increasing the strontium adsorption capacity. Therefore, in the powder X-ray diffraction measurement, it is preferable that the full width at half maximum (FWHM) of the 001 peak when it is assigned as a hexagonal crystal is large. Specifically, the FWHM is preferably 0.4 ° or more and 3.5 ° or less, more preferably 0.4 ° or more and 3.0 ° or less, and further preferably 0.7 ° or more and 2.2 ° or less. Furthermore, when both alkali metals of sodium and potassium are contained and 0.4 ≦ x ≦ 0.6, the FWHM of the 001 peak when assigned as a hexagon in the powder X-ray diffraction experiment is 2.5 ° or more. It was found that the layered manganese oxide molded product having a temperature of 3.5 ° or less has higher strontium adsorption performance.
　本発明の層状マンガン酸化物成形体は、微小圧縮試験機による測定で１０００ｍＮ以上５０００ｍＮ以下の高い圧壊強度を示すことが特徴である。微小圧縮試験機による測定で１０００ｍＮ未満の場合は、機械的強度が不十分であり、５０００ｍＮを超える場合は、多孔性を損なうため、ストロンチウム吸着性能が低下する。保形性及びストロンチウム吸着性能の点から、圧壊強度は２０００ｍＮ以上４０００ｍＮ以下が好ましい。 The layered manganese oxide molded product of the present invention is characterized in that it exhibits a high crushing strength of 1000 mN or more and 5000 mN or less as measured by a microcompression tester. If it is less than 1000 mN as measured by a microcompression tester, the mechanical strength is insufficient, and if it exceeds 5000 mN, the porosity is impaired and the strontium adsorption performance is lowered. From the viewpoint of shape retention and strontium adsorption performance, the crushing strength is preferably 2000 mN or more and 4000 mN or less.
　本発明の層状マンガン酸化物成形体は、通水時の成形体の保形性を評価する指標となる撹拌摩耗度が１５重量％以下であることが好ましい。撹拌摩耗度は、ＪＩＳ－Ｋ－１４６４（工業用乾燥剤の摩耗試験）に準拠して測定することができる。 The layered manganese oxide molded product of the present invention preferably has a stirring wear degree of 15% by weight or less, which is an index for evaluating the shape retention of the molded product during water flow. The degree of agitation wear can be measured in accordance with JIS-K-1464 (wear test of industrial desiccant).
　本発明の層状マンガン酸化物成形体は、無機結合剤および有機成分を含まないことを特徴とする。ここに、無機結合剤および有機成分を含まないとは、各々の測定手段において検出限界以下であることを意味する。吸着に機能しない無機結合剤および有機成分を実質的に含まないことで吸着性能を向上させ、成形体の強度、保形性を維持することができる。無機結合剤として一般的なものとして、ケイ素、アルミニウム、チタンおよびジルコニウム成分などのコロイダル粒子、並びに層状または繊維状ケイ酸塩、具体的にはベントナイトやセピオライトなどを列挙することができ、本発明の層状マンガン酸化物成形体はこれらを含まない。さらに、成形体は有機成分を含まないものであり、成形体中の炭素濃度が３０００ｐｐｍ以下、つまり、各々の測定手段における検出限界以下であることが好ましい。一般的な炭素量測定手段としては、試料の高温燃焼で生成したＣＯまたはＣＯ２量から逆算することで求めることができる。 The layered manganese oxide molded product of the present invention is characterized by containing no inorganic binder and no organic component. Here, the fact that the inorganic binder and the organic component are not contained means that the measurement means is below the detection limit. By substantially not containing an inorganic binder and an organic component that do not function for adsorption, the adsorption performance can be improved, and the strength and shape retention of the molded product can be maintained. Colloidal particles such as silicon, aluminum, titanium and zirconium components, as well as layered or fibrous silicates, specifically bentonite and sepiolite, can be listed as common inorganic binders of the present invention. The layered manganese oxide molded product does not contain these. Further, the molded product does not contain an organic component, and it is preferable that the carbon concentration in the molded product is 3000 ppm or less, that is, not more than the detection limit of each measuring means. As a general carbon content measuring means, it can be obtained by back-calculating from the amount of CO or CO 2 produced by high-temperature combustion of a sample.
　本発明の層状マンガン酸化物成形体は、無機結合剤や有機物増粘剤を含まないため、成形体全てが吸着に機能し、かさ密度も増大させるため、一定体積の吸着塔に対しより多くの重量の吸着剤を充填可能である。さらには、結合剤を使用しないにもかかわらず、粒子の静電的な凝集のみで強固な機械的強度と通水時の保形性を実現可能である。 Since the layered manganese oxide molded product of the present invention does not contain an inorganic binder or an organic thickener, all the molded products function for adsorption and increase the bulk density, so that the amount of the layered manganese oxide molded product is larger than that of a fixed volume adsorption tower. It can be filled with heavy adsorbents. Furthermore, despite the fact that no binder is used, it is possible to achieve strong mechanical strength and shape retention during water flow only by electrostatic agglomeration of particles.
　本発明の層状マンガン酸化物成形体は、全粒体の９０％以上が粒径０．２ｍｍ以上１．７ｍｍ以下の粒体である。粒径０．２ｍｍ以上１．７ｍｍ以下の粒状が全粒体の９０％未満であると、粒度分布が広範となるため、吸着塔の性能が低下する。粒径が０．２ｍｍ未満の粒子が全粒体の１０％を超える場合、成形体を吸着塔に充填した際に圧力損失が高くなる弊害がある。一方、１．７ｍｍを超える粒子が全粒体の１０％を超えると、液接触表面積が減少するため、吸着性能が著しく低下する。全粒体の９５％以上が粒径０．２ｍｍ以上１．７ｍｍ以下の粒体が好ましい。また、全粒体の９０％以上の粒径が０．３ｍｍ以上１．０ｍｍ以下が好ましい。これらは実際の原子力発電所汚染水処理設備の吸着塔に充填することを前提にした粒径である。 In the layered manganese oxide molded product of the present invention, 90% or more of the whole grains are granules having a particle size of 0.2 mm or more and 1.7 mm or less. If the particle size of 0.2 mm or more and 1.7 mm or less is less than 90% of the whole grains, the particle size distribution becomes wide and the performance of the adsorption tower deteriorates. If the particles having a particle size of less than 0.2 mm exceed 10% of the total particles, there is an adverse effect that the pressure loss increases when the molded product is filled in the adsorption tower. On the other hand, when the particles exceeding 1.7 mm exceed 10% of the whole grains, the liquid contact surface area is reduced, so that the adsorption performance is significantly lowered. It is preferable that 95% or more of the whole grains have a particle size of 0.2 mm or more and 1.7 mm or less. Further, it is preferable that the particle size of 90% or more of the whole grain is 0.3 mm or more and 1.0 mm or less. These are the particle sizes that are assumed to be filled in the adsorption tower of the actual contaminated water treatment facility of a nuclear power plant.
　本発明の層状マンガン酸化物成形体は、かさ密度０．９ｇ／ｃｍ３以上であることを特徴とする。１．０ｇ／ｃｍ３以上が好ましい。かさ密度が０．９ｇ／ｃｍ３未満であると、一定体積に充填できる成形体重量が少なくなるため、吸着容量が低下する。 The layered manganese oxide molded product of the present invention is characterized by having a bulk density of 0.9 g / cm 3 or more. 1.0 g / cm 3 or more is preferable. If the bulk density is less than 0.9 g / cm 3 , the weight of the molded product that can be filled in a constant volume is reduced, so that the adsorption capacity is reduced.
　次に、本発明の層状マンガン酸化物成形体の製造について説明する。本発明の層状マンガン酸化物成形体は、少なくともマンガンを含む金属塩水溶液、アルカリ金属水溶液及び酸化剤をアルカリ金属／マンガンモル比が２以上１０以下、反応液の酸化還元電位が飽和カロメル電極基準で－０．２Ｖ以上０．６Ｖ以下、温度０℃以上１００℃以下で混合して混合水溶液を得て、該混合水溶液中で層状マンガン酸化物を析出させる工程１、及び析出した層状マンガン酸化物をろ過した後に析出物質を４０℃以上２００℃以下で熱硬化させる工程２を経ることで得られる。 Next, the production of the layered manganese oxide molded product of the present invention will be described. The layered manganese oxide molded product of the present invention contains at least a metal salt aqueous solution containing manganese, an alkali metal aqueous solution and an oxidizing agent having an alkali metal / manganese molar ratio of 2 or more and 10 or less, and the oxidation-reduction potential of the reaction solution is based on a saturated caromel electrode. Step 1 of obtaining a mixed aqueous solution by mixing at −0.2 V or more and 0.6 V or less and a temperature of 0 ° C. or higher and 100 ° C. or lower and precipitating the layered manganese oxide in the mixed aqueous solution, and the precipitated layered manganese oxide It is obtained by undergoing step 2 in which the precipitated substance is thermally cured at 40 ° C. or higher and 200 ° C. or lower after filtration.
　工程１に用いるマンガンを含む金属塩水溶液は、マンガンを含む金属塩を水に溶解させることで調製することができる。マンガンを含む金属塩は、例えば、水溶性の硫酸マンガン（ＩＩ）、塩化マンガン（ＩＩ）、硝酸マンガン（ＩＩ）、酢酸マンガン（ＩＩ）などが挙げられ、無水物であっても水和物であってもよい。これらのうち、硫酸マンガン（ＩＩ）が廃液処理、腐食性、原料コストを考慮した場合、最も好適である。また、層状マンガン酸化物の生成を阻害しない限り、マンガンと他の金属イオンとを混合して用いることも可能である。金属塩水溶液中のアルカリ土類金属濃度は低いことが必須であり、総アルカリ土類金属濃度が１５００ｐｐｍ未満であることが必要である。アルカリ土類金属濃度が１５００ｐｐｍ以上の原料液を用いた場合、副生相を生じると共に、層状構造が発達したマンガン酸化物が得られず、ストロンチウム吸着性能が低下する。総アルカリ土類金属濃度は、１０００ｐｐｍ未満が好ましく、５００ｐｐｍがより好ましく、１００ｐｐｍ未満がさらに好ましい。金属塩水溶液中のマンガンなどの全金属の合計濃度（金属濃度）は任意であるが、金属濃度は生産性に影響を及ぼすため、１．０ｍｏｌ／Ｌ以上が好ましく、２．０ｍｏｌ／Ｌ以上がさらに好ましい。 The manganese-containing metal salt aqueous solution used in step 1 can be prepared by dissolving the manganese-containing metal salt in water. Examples of the metal salt containing manganese include water-soluble manganese sulfate (II), manganese chloride (II), manganese nitrate (II), manganese acetate (II), and the like, and even if it is anhydrous, it is a hydrate. There may be. Of these, manganese sulfate (II) is most suitable in consideration of waste liquid treatment, corrosiveness, and raw material cost. Further, manganese and other metal ions can be mixed and used as long as the formation of the layered manganese oxide is not inhibited. It is essential that the alkaline earth metal concentration in the metal salt aqueous solution is low, and the total alkaline earth metal concentration must be less than 1500 ppm. When a raw material solution having an alkaline earth metal concentration of 1500 ppm or more is used, a by-product phase is formed and a manganese oxide having a developed layered structure cannot be obtained, resulting in a decrease in strontium adsorption performance. The total alkaline earth metal concentration is preferably less than 1000 ppm, more preferably 500 ppm, and even more preferably less than 100 ppm. The total concentration (metal concentration) of all metals such as manganese in the metal salt aqueous solution is arbitrary, but the metal concentration affects productivity, so 1.0 mol / L or more is preferable, and 2.0 mol / L or more is preferable. More preferred.
　工程１に用いるアルカリ金属水溶液は、アルカリ金属化合物を水に溶解させることで調製することができる。アルカリ金属化合物は、例えば、水酸化ナトリウム又は水酸化カリウムなどの水酸化アルカリ金属、炭酸ナトリウム又は炭酸カリウムなどの炭酸アルカリ金属などが水溶性とコストおよびｐＨ調整の点から好適である。また、アルカリ金属水溶液のアルカリ金属濃度は、生産性の観点から１ｍｏｌ／Ｌ以上を例示することができる。アルカリ金属／マンガンモル比は２以上１０以下である。２未満であると、四三酸化マンガン（Ｍｎ３Ｏ４）が副生し、１０を超える場合も、四三酸化マンガン（Ｍｎ３Ｏ４）が副生する。ストロンチウム吸着性能の点から、３以上８以下であることが好ましい。 The alkali metal aqueous solution used in step 1 can be prepared by dissolving the alkali metal compound in water. As the alkali metal compound, for example, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, an alkali metal carbonate such as sodium carbonate or potassium carbonate, or the like is suitable from the viewpoint of water solubility, cost, and pH adjustment. Further, the alkali metal concentration of the alkali metal aqueous solution can be exemplified as 1 mol / L or more from the viewpoint of productivity. The alkali metal / manganese molar ratio is 2 or more and 10 or less. If it is less than 2, manganese tetraoxide (Mn 3 O 4 ) is by-produced, and if it exceeds 10, manganese tetraoxide (Mn 3 O 4 ) is by-produced. From the viewpoint of strontium adsorption performance, it is preferably 3 or more and 8 or less.
　工程１に用いる酸化剤としては、例えば、過酸化水素、酸素、空気、およびペルオキソ二硫酸塩などが挙げられる。ペルオキソ二硫酸塩としては、ペルオキソ二硫酸ナトリウム、ペルオキソ二硫酸カリウム、ペルオキソ二硫酸アンモニウムなどが例示できる。このうち原料調達の容易さおよびコストの点で過酸化水素水、酸素又は空気が好ましい。さらに経済上、酸素又は空気が好ましく、空気がより好ましい。空気や酸素などのガスはバブラーなどを用いて混合水溶液中にバブリングさせることで添加する。 Examples of the oxidizing agent used in step 1 include hydrogen peroxide, oxygen, air, and peroxodisulfate. Examples of the peroxodisulfate include sodium peroxodisulfate, potassium peroxodisulfate, and ammonium peroxodisulfate. Of these, hydrogen peroxide solution, oxygen or air is preferable in terms of ease of raw material procurement and cost. Further economically, oxygen or air is preferable, and air is more preferable. Gases such as air and oxygen are added by bubbling in a mixed aqueous solution using a bubbler or the like.
　工程１における反応液の酸化還元電位を飽和カロメル電極基準で－０．２Ｖ以上０．６Ｖ以下に調整することにより混合水溶液が得られ、該混合水溶液から本発明の層状マンガン酸化物が析出する。当該酸化還元電位範囲を外れると、副生成物としてＭｎ３Ｏ４や過マンガン酸塩が生成する。Ｍｎ３Ｏ４は、ストロンチウム吸着には不活性であることから、その生成はストロンチウム吸着性能低下につながる。また、同じく当該酸化還元電位範囲を外れると、本発明の層状マンガン酸化物成形体の強度が低下する。より好ましい酸化還元電位範囲は飽和カロメル電極基準で－０．１Ｖ以上０．５Ｖ以下である。なお、反応液の酸化還元電位は一般的な標準水素電極を基準とした値であり、市販の酸化還元電位計により求めることができる。酸化還元電位は酸化剤の供給量や反応温度により制御可能である。 A mixed aqueous solution is obtained by adjusting the redox potential of the reaction solution in step 1 to −0.2 V or more and 0.6 V or less based on the saturated calomel electrode, and the layered manganese oxide of the present invention is precipitated from the mixed aqueous solution. When the redox potential range is exceeded, Mn 3 O 4 and permanganate are produced as by-products. Since Mn 3 O 4 is inactive for strontium adsorption, its formation leads to a decrease in strontium adsorption performance. Similarly, if the redox potential range is exceeded, the strength of the layered manganese oxide molded product of the present invention decreases. A more preferable redox potential range is −0.1 V or more and 0.5 V or less based on the saturated calomel electrode. The redox potential of the reaction solution is a value based on a general standard hydrogen electrode, and can be obtained by a commercially available redox potential meter. The redox potential can be controlled by the supply amount of the oxidizing agent and the reaction temperature.
　工程１にて、マンガンを含む金属塩水溶液、アルカリ金属水溶液及び酸化剤を混合する温度は０℃以上１００℃以下である。混合する温度が０℃未満であると酸化反応が進まないとともに反応液が凝固する可能性があり、１００℃を超えると粒子成長が進むことで目的とする緻密な凝集体が得られない。酸化反応が進みやすくなり、層状マンガン酸化物がより析出しやすくなるため、４０℃以上８０℃以下が好ましい。 In step 1, the temperature at which the aqueous metal salt solution containing manganese, the aqueous alkali metal solution and the oxidizing agent are mixed is 0 ° C. or higher and 100 ° C. or lower. If the mixing temperature is less than 0 ° C., the oxidation reaction may not proceed and the reaction solution may solidify, and if it exceeds 100 ° C., particle growth proceeds and the desired dense aggregate cannot be obtained. Since the oxidation reaction is likely to proceed and the layered manganese oxide is more likely to be precipitated, the temperature is preferably 40 ° C. or higher and 80 ° C. or lower.
　工程１にて、マンガンを含む金属塩水溶液、アルカリ金属水溶液及び酸化剤を混合する際は、バッチ式、連続式反応のどちらでも構わない。混合終了時のｐＨは７以上１４以下であることが好ましく、ｐＨ、反応液の酸化還元電位はマンガンを含む金属塩又はアルカリ金属水溶液いずれかの投入速度を制御することで適宜調整可能である。また、金属水溶液とアルカリ金属水溶液の添加方法については、アルカリ金属／マンガンモル比を一定にした上で同時に等速滴下することが緻密で強度と吸着性能が高い成型体が得られるため、好ましい。さらに混合の際の攪拌については、少なくともマンガンを含む金属塩水溶液、アルカリ金属水溶液及び酸化剤を混合する際の攪拌所要動力が０．５ｋＷ／ｍ３以上が必要である。攪拌所要動力が０．５ｋＷ／ｍ３未満のように攪拌が不十分であると、副生相を生じ、目的とする緻密な凝集体が得られない。１ｋＷ／ｍ３以上が好ましく、５ｋＷ／ｍ３上がより好ましい。 When the metal salt aqueous solution containing manganese, the alkali metal aqueous solution and the oxidizing agent are mixed in step 1, either a batch type or a continuous type reaction may be used. The pH at the end of mixing is preferably 7 or more and 14 or less, and the pH and the oxidation-reduction potential of the reaction solution can be appropriately adjusted by controlling the charging rate of either a metal salt containing manganese or an aqueous alkali metal solution. Further, as for the method of adding the metal aqueous solution and the alkali metal aqueous solution, it is preferable to keep the alkali metal / manganese molar ratio constant and then drop them at a constant velocity at the same time because a dense molded body having high strength and adsorption performance can be obtained. Further, for stirring at the time of mixing, at least the required power for stirring at the time of mixing the metal salt aqueous solution containing manganese, the alkali metal aqueous solution and the oxidizing agent is required to be 0.5 kW / m 3 or more. If the stirring power is insufficient such that the required power for stirring is less than 0.5 kW / m 3 , a by-product phase is generated and the desired dense aggregate cannot be obtained. Preferably 1 kW / m 3 or more, 5 kW / m 3 above is more preferable.
　工程１において原料液を混合して得られるスラリー中の固形分濃度については、１ｗｔ％以上５ｗｔ％以下であることが必要である。生産性を確保するためには高濃度が望ましいが、５ｗｔ％を超えると緻密な凝集体が得られない傾向がある。この際、生産効率と緻密性とを両立するには、３ｗｔ％以上４ｗｔ％以下が好適である。 The solid content concentration in the slurry obtained by mixing the raw material liquid in step 1 needs to be 1 wt% or more and 5 wt% or less. A high concentration is desirable to ensure productivity, but if it exceeds 5 wt%, a dense aggregate tends not to be obtained. At this time, in order to achieve both production efficiency and precision, 3 wt% or more and 4 wt% or less are preferable.
　工程２において、工程１にて析出した層状マンガン酸化物のろ過方法は、固液分離可能であれば、特に制限はない。工業的にはベルトフィルター、フィルタープレス、加圧ろ過装置、限外ろ過装置などを使用することができる。ろ過時に層状マンガン酸化物の洗浄を行ってもよい。 In step 2, the method for filtering the layered manganese oxide precipitated in step 1 is not particularly limited as long as solid-liquid separation is possible. Industrially, a belt filter, a filter press, a pressure filtration device, an ultrafiltration device and the like can be used. The layered manganese oxide may be washed during filtration.
　工程２において、層状マンガン酸化物を熱硬化させ、本発明の層状マンガン酸化物成形体を製造する際の温度は、本発明の層状マンガン酸化物成形体の保形性の点から、４０℃以上２００℃以下で行うもので、４０℃以上１６０℃以下で行うことが好ましい。なお、該熱硬化処理は、ろ過により得られた層状マンガン酸化物のろ過ケーキを乾燥させる処理を兼ねてもよい。この熱硬化処理により、工程１で得られた層間距離９から１０オングストロームのブセライト型層状マンガン酸化物は、層間距離７．０から７．３オングストロームのバーネサイト型層状マンガン酸化物に変化し、ろ過ケーキの体積収縮（高密度化）と熱硬化が起こる。熱硬化処理は、ろ過ケーキをそのままの形状で、あるいは適当に解砕または成形した後に行われる。熱硬化処理の時間は硬化の進行に従って適宜決定される。以上のように、温和な乾燥条件にすることで、高硬度で高密度な凝集体である粒状成形体が得られるため、適宜、熱硬化条件（ろ過ケーキの乾燥時形状、温度、時間）を制御することにより達成される。ロータリー式乾燥やフラッシュ式乾燥は粒径が０．２ｍｍ未満の粒子を形成しやすく、不適である。 In step 2, the temperature at which the layered manganese oxide is thermoset to produce the layered manganese oxide molded product of the present invention is 40 ° C. or higher from the viewpoint of shape retention of the layered manganese oxide molded product of the present invention. It is carried out at 200 ° C. or lower, and is preferably carried out at 40 ° C. or higher and 160 ° C. or lower. The thermosetting treatment may also serve as a treatment for drying the filtered cake of the layered manganese oxide obtained by filtration. By this heat curing treatment, the buserite-type layered manganese oxide having an interlayer distance of 9 to 10 angstroms obtained in step 1 is changed to a burnesite-type layered manganese oxide having an interlayer distance of 7.0 to 7.3 angstroms, and the filtered cake. Volume shrinkage (high density) and thermal curing occur. The thermosetting treatment is performed after the filtered cake is in its original shape or is appropriately crushed or molded. The time of the thermosetting treatment is appropriately determined according to the progress of curing. As described above, by setting the drying conditions to be mild, a granular molded product which is a high-hardness and high-density agglomerate can be obtained. Therefore, the thermosetting conditions (drying shape, temperature, time of the filtered cake) are appropriately set. Achieved by controlling. Rotary drying and flash drying are not suitable because they tend to form particles with a particle size of less than 0.2 mm.
　本発明の層状マンガン酸化物成形体の成形は、ろ過ケーキを熱硬化させた後に、さらに、必要に応じ、破砕・分級することにより、全粒体の９０％以上が粒径０．２ｍｍ以上１．７ｍｍ以下の粒体になるように行われる。破砕法は特に制限はなく、一般的な破砕機、例えばコーンクラッシャー、ロールクラッシャーなどのクラッシャー式破砕機、カッターミル、スタンプミル、リングミル、ローラーミル、ジェットミル、ハンマーミル、回転ミル（ボールミル）、振動ミルなどのミル式破砕機などにより行うことができる。分級法は、乾式分級又は湿式分級のいずれの方法も使用でき、水力分級機、沈降分級機、機械式分級機、気流分級機、重力分級機、サイクロン式分級機、ふるい式分級機などを適宜用いて分級することができる。 In the molding of the layered manganese oxide molded product of the present invention, 90% or more of the total granules have a particle size of 0.2 mm or more by thermosetting the filtered cake and then crushing and classifying the cake as necessary. It is performed so that the particles are 0.7 mm or less. The crushing method is not particularly limited, and general crushers such as cone crushers, crusher type crushers such as roll crushers, cutter mills, stamp mills, ring mills, roller mills, jet mills, hammer mills, rotary mills (ball mills), It can be performed by a mill type crusher such as a vibration mill. As the classification method, either dry classification or wet classification can be used, and a hydraulic classification machine, a sedimentation classification machine, a mechanical classification machine, an air flow classification machine, a gravity classification machine, a cyclone type classification machine, a sieving type classification machine, etc. can be appropriately used. Can be used for classification.
　本発明の層状マンガン酸化物成形体は、例えば、ストロンチウム吸着剤、あるいは他の重金属吸着用に使用することができる。 The layered manganese oxide molded product of the present invention can be used, for example, for adsorbing strontium adsorbents or other heavy metals.
　ストロンチウム吸着剤としては、多種かつ多量の共存イオンが存在する処理液から、ストロンチウムを選択吸着するのに有用である。 As a strontium adsorbent, it is useful for selectively adsorbing strontium from a treatment liquid in which a large amount of coexisting ions are present.
　〔まとめ〕
　以上の通り、本発明は、以下の構成よりなる。 [Summary]
As described above, the present invention has the following configuration.
　［１］　少なくともアルカリ金属とマンガンとを含む層状マンガン酸化物から構成されており、微小圧縮試験機による測定で１０００ｍＮ以上５０００ｍＮ以下の圧壊強度を有し、無機結合剤および有機成分を含まず、全粒体の９０％以上が粒径０．２ｍｍ以上１．７ｍｍ以下の粒体であり、かさ密度０．９ｇ／ｃｍ３以上である、層状マンガン酸化物成形体。 [1] It is composed of a layered manganese oxide containing at least an alkali metal and manganese, has a crushing strength of 1000 mN or more and 5000 mN or less as measured by a microcompression tester, and does not contain an inorganic binder or an organic component. A layered manganese oxide molded product in which 90% or more of the granules have a particle size of 0.2 mm or more and 1.7 mm or less and a bulk density of 0.9 g / cm 3 or more.
　［２］　組成式ＡｘＭｎＯ２で表され、Ａは、ナトリウム及びカリウムから選ばれる少なくとも１種以上のアルカリ金属を表し、０．２≦ｘ≦０．６である、上記［１］に記載の層状マンガン酸化物成形体。 [2] Described in the above [1], which is represented by the composition formula A x MnO 2 , where A represents at least one alkali metal selected from sodium and potassium, and 0.2 ≦ x ≦ 0.6. Layered manganese oxide molded product.
　［３］　上記層状マンガン酸化物の層間距離が７．０オングストローム以上７．３オングストローム以下である、上記［１］または［２］に記載の層状マンガン酸化物成形体。 [3] The layered manganese oxide molded product according to the above [1] or [2], wherein the interlayer distance between the layered manganese oxides is 7.0 angstroms or more and 7.3 angstroms or less.
　［４］　粉末Ｘ線回折実験において六方晶で帰属した場合の００１ピークのＦＷＨＭが０．４°以上３．５°以下である、上記［１］～［３］のいずれか一項に記載の層状マンガン酸化物成形体。 [4] The item according to any one of [1] to [3] above, wherein the FWHM of the 001 peak when assigned as a hexagonal crystal in the powder X-ray diffraction experiment is 0.4 ° or more and 3.5 ° or less. Layered manganese oxide compact.
　［５］　組成式ＡｘＭｎＯ２で表され、Ａは、少なくともナトリウムとカリウムとを含むアルカリ金属であり、０．４≦ｘ≦０．６であり、粉末Ｘ線回折実験において六方晶で帰属した場合の００１ピークのＦＷＨＭが２．５°以上３．５°以下である、上記［１］～［４］のいずれかの項に記載の層状マンガン酸化物成形体。 [5] Represented by the composition formula A x MnO 2 , A is an alkali metal containing at least sodium and potassium, 0.4 ≦ x ≦ 0.6, and is assigned as a hexagon in a powder X-ray diffraction experiment. The layered manganese oxide molded product according to any one of the above [1] to [4], wherein the FWHM of the 001 peak is 2.5 ° or more and 3.5 ° or less.
　［６］　上記アルカリ金属がカリウムである、上記［１］～［５］のいずれか一項に記載の層状マンガン酸化物成形体。 [6] The layered manganese oxide molded product according to any one of the above [1] to [5], wherein the alkali metal is potassium.
　［７］　撹拌摩耗度が１５重量％以下である、上記［１］～［６］のいずれか一項に記載の層状マンガン酸化物成形体。 [7] The layered manganese oxide molded product according to any one of the above [1] to [6], wherein the degree of agitation wear is 15% by weight or less.
　［８］　上記無機結合剤が、ケイ素、アルミニウム、チタン及びジルコニウム成分から選択される少なくとも１種の無機結合剤である、上記［１］～［７］のいずれか一項に記載の層状マンガン酸化物成形体。 [8] The layered manganese oxidation according to any one of the above [1] to [7], wherein the inorganic binder is at least one inorganic binder selected from silicon, aluminum, titanium and zirconium components. Object molded body.
　［９］　炭素濃度が３０００ｐｐｍ以下である上記［１］～［８］のいずれか一項に記載の層状マンガン酸化物成形体。 [9] The layered manganese oxide molded product according to any one of the above [1] to [8], which has a carbon concentration of 3000 ppm or less.
　［１０］　少なくともマンガンを含み、アルカリ土類金属の濃度が１５００ｐｐｍ未満である金属塩水溶液、アルカリ金属水溶液及び酸化剤を、アルカリ金属／マンガンモル比が２以上１０以下、酸化還元電位が飽和カロメル電極基準で－０．２Ｖ以上０．６Ｖ以下、温度０℃以上１００℃以下、単位容積あたりの攪拌所要動力が０．５ｋＷ／ｍ３以上で混合して混合水溶液を得て、該混合水溶液中でスラリーの固形分濃度が１ｗｔ％以上５ｗｔ％以下で析出させた上で、ろ過した後に析出物質を４０℃以上２００℃以下で熱硬化させる、上記［１］～［９］のいずれか一項に記載の層状マンガン酸化物成形体の製造方法。 [10] A metal salt aqueous solution, an alkali metal aqueous solution and an oxidizing agent containing at least manganese and having an alkaline earth metal concentration of less than 1500 ppm, having an alkali metal / manganese molar ratio of 2 or more and 10 or less, and a saturated caromel electrode having an oxidation-reduction potential. A mixed aqueous solution is obtained by mixing at -0.2 V or more and 0.6 V or less, a temperature of 0 ° C. or more and 100 ° C. or less, and a required stirring power per unit volume of 0.5 kW / m 3 or more, and in the mixed aqueous solution. In any one of the above [1] to [9], the solid content concentration of the slurry is precipitated at 1 wt% or more and 5 wt% or less, and then the precipitated substance is thermally cured at 40 ° C. or higher and 200 ° C. or lower after filtration. The method for producing a layered manganese oxide molded product according to the above method.
　［１１］　上記アルカリ金属がカリウムである、上記［１０］に記載の層状マンガン酸化物成形体の製造方法。 [11] The method for producing a layered manganese oxide molded product according to the above [10], wherein the alkali metal is potassium.
　［１２］　上記酸化剤が過酸化水素、酸素、空気、およびペルオキソ二硫酸塩からなる群より選ばれる少なくとも１つである、上記［１０］または［１１］に記載の層状マンガン酸化物成形体の製造方法。 [12] The layered manganese oxide molded product according to the above [10] or [11], wherein the oxidizing agent is at least one selected from the group consisting of hydrogen peroxide, oxygen, air, and peroxodisulfate. Production method.
　［１３］　上記混合水溶液中で析出させる上記析出物質が、層間距離９オングストローム以上１０オングストローム以下のブセライトであって、該析出物質が熱硬化過程で層間距離７．０オングストローム以上７．３オングストローム以下のバーネサイトとなる、上記［１０］～［１２］のいずれか一項に記載の層状マンガン酸化物成形体の製造方法。 [13] The precipitated substance to be precipitated in the mixed aqueous solution is bucelite having an interlayer distance of 9 angstroms or more and 10 angstroms or less, and the precipitated substance has an interlayer distance of 7.0 angstroms or more and 7.3 angstroms or less in the heat curing process. The method for producing a layered manganese oxide molded product according to any one of the above [10] to [12], which serves as a burnesite.
　［１４］　上記［１］～［９］のいずれか一項に記載の層状マンガン酸化物成形体を含有する、ストロンチウム吸着剤。 [14] A strontium adsorbent containing the layered manganese oxide molded product according to any one of the above [1] to [9].
　以下、本発明を実施例により更に詳細に説明するが、本発明はこれらに限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.
　＜元素組成の測定＞
　得られた試料の元素組成分析は誘導結合プラズマ発光分析法（ＩＣＰ法）により行った。すなわち、試料粉末を過酸化水素水とフッ化水素酸とで加圧酸溶解することで、測定溶液を調製した。誘導結合プラズマ発光分析装置（商品名：ＯＰＴＩＭＡ３０００ＤＶ、ＰＥＲＫＩＮ　ＥＬＭＥＲ製）を用い、得られた測定溶液を測定することで、得られた試料の元素組成を分析した。 <Measurement of elemental composition>
The elemental composition analysis of the obtained sample was performed by inductively coupled plasma emission spectrometry (ICP method). That is, a measurement solution was prepared by dissolving the sample powder under pressure with hydrogen peroxide solution and hydrofluoric acid. The elemental composition of the obtained sample was analyzed by measuring the obtained measurement solution using an inductively coupled plasma emission spectrometer (trade name: OPTIMA3000DV, manufactured by PERKIN ELMER).
　＜炭素濃度の測定＞
　試料の炭素濃度分析は、全自動元素分析装置（ＰＥ２４００シリーズ２　ＣＨＮＳ／Ｏ　Ａｎａｌｙｚｅｒ、パーキンエルマー製）を用いて行った。 <Measurement of carbon concentration>
The carbon concentration analysis of the sample was performed using a fully automatic elemental analyzer (PE2400 series 2 CHNS / O Analyzer, manufactured by PerkinElmer).
　　測定条件：燃焼温度９５０℃、還元温度６４０℃
　＜粉末Ｘ線回折測定＞
　粉末Ｘ線回折装置（商品名：Ｕｌｔｉｍａ４、リガク製）を使用し、得られた試料の粉末Ｘ線回折測定を行った。線源にはＣｕＫα線（λ＝１．５４０５Å）を用い、測定モードはステップスキャン、スキャン条件は毎秒０．０４°、計測時間は０．２５秒、測定範囲は２θとして５°から９０°の範囲で測定した。 Measurement conditions: Combustion temperature 950 ° C, reduction temperature 640 ° C
<Powder X-ray diffraction measurement>
Using a powder X-ray diffractometer (trade name: Ultima4, manufactured by Rigaku), powder X-ray diffraction measurement of the obtained sample was performed. CuKα ray (λ = 1.5405Å) is used as the radiation source, the measurement mode is step scan, the scan condition is 0.04 ° per second, the measurement time is 0.25 seconds, and the measurement range is 2θ from 5 ° to 90 °. Measured in the range.
　＜圧壊強度測定＞
　微小圧縮試験機（商品名：ＭＣＴ－５１０、島津製作所製）を使用して、試料の圧壊強度を測定した。圧壊強度は、ダイヤモンド圧盤にて試料に負荷を加える方法で測定した。ランダムに取り出した成形体顆粒を試料台に置き、ダイヤモンド圧盤を自動的に下げ、粒子が崩壊した際の試験力を圧壊強度とした。なお、圧壊強度は負荷時のダイヤモンド圧盤の変位が最も大きい際の試験力とした。なお、マイクロスコープによる観察から、崩壊以前の、粒子の微細な動きとみられる変位は除外した。）この測定を２５個繰り返し、その平均値を成形体の圧壊強度とした。 <Measurement of crush strength>
The crushing strength of the sample was measured using a microcompression tester (trade name: MCT-510, manufactured by Shimadzu Corporation). The crushing strength was measured by applying a load to the sample with a diamond platen. Randomly taken out molded granules were placed on a sample table, the diamond platen was automatically lowered, and the test force when the particles collapsed was taken as the crushing strength. The crushing strength was the test force when the displacement of the diamond platen under load was the largest. From the observation with a microscope, the displacement that seems to be the fine movement of the particles before the collapse was excluded. ) This measurement was repeated 25 times, and the average value was taken as the crushing strength of the molded product.
　＜撹拌摩耗度の測定＞
　撹拌摩耗度の測定は、ＪＩＳ－Ｋ－１４６４（工業用乾燥剤の摩耗試験）及び米国特許５９２５２８４号公報に準拠して行った。すなわち、水７．５ｇ、及び成形体を乾燥重量で２．５ｇ、３０ｍＬ広口ポリエチレン瓶に入れ、２５℃、２４時間静置した。ポリエチレン瓶を、ペイントシェイカー（東洋精機製作所製）を用いて５分間振とう撹拌し、摩耗により成形体から脱落した脱落物を、１００ｍｅｓｈ（目開き１５０μｍ）篩にかけることで分離回収し、２００℃、１２時間乾燥した際の乾燥後の脱落物重量を以下の式で算出した。 <Measurement of agitation wear>
The degree of agitation wear was measured in accordance with JIS-K-1464 (wear test of industrial desiccant) and US Pat. No. 5,925,284. That is, 7.5 g of water and the molded product were placed in a 30 mL wide-mouthed polyethylene bottle having a dry weight of 2.5 g and allowed to stand at 25 ° C. for 24 hours. The polyethylene bottle is shaken and stirred for 5 minutes using a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.). , The weight of the shed material after drying after drying for 12 hours was calculated by the following formula.
　　撹拌摩耗度（重量％）＝（脱落物の重量／撹拌前の成形体の乾燥重量）×１００
　＜かさ密度の測定＞
　試料のかさ密度は、以下の方法により測定した。粒度を０．３～０．６ｍｍに分級した成形体を、乾燥重量で５ｇをはかり取った。この所定重量の成形体を、自然落下によりメスシリンダー内に収め、メスシリンダー目盛より体積を読みとり、以下の式によりかさ密度を算出した。 Stirring wear (% by weight) = (weight of dropped material / dry weight of molded product before stirring) x 100
<Measurement of bulk density>
The bulk density of the sample was measured by the following method. A molded product having a particle size of 0.3 to 0.6 mm was weighed by 5 g by dry weight. This molded body of a predetermined weight was placed in a graduated cylinder by free fall, the volume was read from the graduated cylinder scale, and the bulk density was calculated by the following formula.
　　かさ密度＝Ｗ／Ｖ（ｇ／ｃｍ３）
　　　Ｗ：層状マンガン酸化物成形体の乾燥重量（ｇ）
　　　Ｖ：メスシリンダーの読み取り値（ｃｍ３）
　＜ストロンチウム吸着試験＞
　汚染海水を模擬し、塩化ナトリウム、塩化ストロンチウム６水和物、塩化カルシウム、塩化マグネシウム６水和物、塩化セシウムの試薬を所定量秤量し純水で希釈することにより、ＮａＣｌ：０．３％、Ｃａ２＋：５ｐｐｍ、Ｍｇ２＋：２ｐｐｍ、Ｓｒ２＋：５ｐｐｍ、Ｃｓ＋：１ｐｐｍであるｐＨ７の被処理液Ａ（以下、「模擬海水Ａ」とする）、ＮａＣｌ：０．３％、Ｃａ２＋：７０ｐｐｍ、Ｍｇ２＋：４０ｐｐｍ、Ｓｒ２＋：５ｐｐｍ、Ｃｓ＋：１ｐｐｍであるｐＨ７の被処理液Ｂ（以下、「模擬海水Ｂ」とする）を調製し、さらに、被処理液Ａを１Ｎ－ＮａＯＨ水溶液でｐＨ調整し、ＮａＣｌ：０．３％、Ｃａ２＋：５ｐｐｍ、Ｍｇ２＋：０ｐｐｍ、Ｓｒ２＋：５ｐｐｍ、Ｃｓ＋：１ｐｐｍであるｐＨ１２の被処理液Ｃ（以下、「模擬海水Ｃ」とする）を調製した。 Bulk density = W / V (g / cm 3 )
W: Dry weight (g) of the layered manganese oxide molded product
V: Graduated cylinder reading (cm 3 )
<Strontium adsorption test>
By simulating contaminated seawater, weigh the reagents of sodium chloride, strontium chloride hexahydrate, calcium chloride, magnesium chloride hexahydrate, and cesium chloride in predetermined amounts and dilute with pure water to obtain NaCl: 0.3%. Ca 2+ : 5ppm, Mg 2+ : 2ppm, Sr 2+ : 5ppm, Cs + : 1ppm, pH 7 object to be treated A (hereinafter referred to as "simulated seawater A"), NaCl: 0.3%, Ca 2+ : 70ppm , Mg 2+ : 40 ppm, Sr 2+ : 5 ppm, Cs + : 1 ppm, pH 7 to be treated liquid B (hereinafter referred to as “simulated seawater B”) was prepared, and further, the liquid to be treated A was prepared with a 1N-NaOH aqueous solution. Adjust the pH and add a pH 12 object to be treated C (hereinafter referred to as "simulated seawater C") having NaCl: 0.3%, Ca 2+ : 5 ppm, Mg 2+ : 0 ppm, Sr 2+ : 5 ppm, Cs +: 1 ppm. Prepared.
　層状マンガン酸化物成形体を３０分水に浸漬させ空気抜きを行った後、内径８ｍｍのカラムに５ｍＬ充填し、１時間純水を１００ｍＬ／ｈｒの速度で通液させた後、カラム温度を３０℃に保持しながら模擬海水Ａ～Ｃをカラムに１００ｍＬ／ｈｒの速度で通液させ続け、カラムに通液させて得た処理模擬海水（以下、「処理液Ａ～Ｃ」という）を以後２４時間毎に１００ｍＬずつサンプリングを行った。 After immersing the layered manganese oxide compact in water for 30 minutes to bleed air, fill a column with an inner diameter of 8 mm with 5 mL, pass pure water at a rate of 100 mL / hr for 1 hour, and then set the column temperature to 30 ° C. The simulated seawater A to C was continuously passed through the column at a rate of 100 mL / hr, and the treated simulated seawater (hereinafter referred to as “treatment liquids A to C”) obtained by passing the liquid through the column was continuously passed through the column for 24 hours thereafter. 100 mL was sampled each time.
　処理液中のストロンチウム濃度測定は誘導結合プラズマ発光分析法（ＩＣＰ法）により行った。測定には一般的な誘導結合プラズマ発光分析装置（商品名：ＯＰＴＩＭＡ３０００ＤＶ、ＰＥＲＫＩＮ　ＥＬＭＥＲ社製）を用い、処理液を測定することでストロンチウム濃度を求めた。 The strontium concentration in the treatment liquid was measured by inductively coupled plasma emission spectrometry (ICP method). The strontium concentration was determined by measuring the treatment liquid using a general inductively coupled plasma emission spectrometer (trade name: OPTIMA3000DV, manufactured by PERKIN ELMER).
　吸着試験を行う前の模擬海水のストロンチウム濃度をＣ０（ｍｇ／Ｌ）、処理液のストロンチウム濃度をＣ（ｍｇ／Ｌ）とし、Ｃ／Ｃ０を模擬海水通液開始からサンプリング時刻までの単位吸着剤体積あたりの総模擬海水通液量（以下、「Ｂ．Ｖ．」とする）に対してプロットし、Ｃ／Ｃ０＝０．１となるまでのＢ．Ｖ．（以下、「破過Ｂ．Ｖ．」とする）を求めた。 The strontium concentration of the simulated seawater before the adsorption test is C 0 (mg / L), the strontium concentration of the treatment solution is C (mg / L), and C / C 0 is the unit from the start of the simulated seawater flow to the sampling time. Plot against the total simulated seawater flow volume per adsorbent volume (hereinafter referred to as "VV"), and B.C. until C / C 0 = 0.1. V. (Hereinafter, it will be referred to as "Breakthrough BV").
　＜粒径０．２ｍｍ以上１．７ｍｍ以下に相当する粒体重量分率の測定方法＞
　試料を目開き１．７ｍｍ（１０メッシュ）および目開き０．２１ｍｍ（７０メッシュ）の金属製ふるいに通した。０．２ｍｍから１．７ｍｍの粒径に相当する粒体重量分率は目開き１．７ｍｍのふるい上および目開き０．２１ｍｍのふるい下の粒体の重量Ａを全粒体の重量Ｂを用いて以下の式で求めた。 <Measuring method of particle weight fraction corresponding to particle size of 0.2 mm or more and 1.7 mm or less>
The sample was passed through a metal sieve with an opening of 1.7 mm (10 mesh) and an opening of 0.21 mm (70 mesh). The weight fraction of the granular material corresponding to the particle size of 0.2 mm to 1.7 mm is the weight A of the granular material above the sieve with a mesh opening of 1.7 mm and the weight A under the sieve with a mesh opening of 0.21 mm, and the weight B of the whole granular material. It was calculated by the following formula.
　粒径０．２ｍｍ以上１．７ｍｍ以下に相当する粒体重量分率（％）＝１００×（Ｂ－Ａ）／Ｂ
　＜攪拌所要動力の計算方法＞
　単位容積あたりの攪拌所要動力は下記の式により求めた。 Granular material weight fraction (%) corresponding to a particle size of 0.2 mm or more and 1.7 mm or less = 100 × (BA) / B
<Calculation method of required power for stirring>
The required stirring power per unit volume was calculated by the following formula.
　　　　Ｐ＝Ｎｐ・ρ・ｎ３・ｄ５
　　　Ｐｖ＝Ｐ／Ｖ
　（Ｐ：攪拌所要動力［Ｗ］、Ｐｖ：体積当たりの攪拌所要動力［ｋＷ／ｍ３］、ρ：密度［ｋｇ／ｍ３］、ｎ：回転数［ｒｐｓ］、ｄ：翼スパン［ｍ］、Ｎｐ：動力数［－］、Ｖ：体積［Ｌ］）
　なお、Ｎｐ：動力数については１０Ｌ反応槽、パドル翼では１．１、１Ｌ反応槽、パドル翼では１．８を用いた。その他のパラメーターについては、ρ：密度は１．２２ｇ／ｃｃ、ｄ：翼スパンは１０Ｌ反応槽、パドル翼では１２８ｍｍ、１Ｌ反応槽、パドル翼では８０ｍｍ、Ｖ：体積については１０Ｌ反応槽→５Ｌ（実施例３）、１Ｌ反応槽→０．７Ｌ（実施例１、４および比較例２、３）、０．３Ｌ（比較例４）を使用した。 P = Np ・ ρ ・ n 3・ d 5
Pv = P / V
(P: Power required for stirring [W], Pv: Power required for stirring per volume [kW / m 3 ], ρ: Density [kg / m 3 ], n: Rotation speed [rps], d: Blade span [m] , Np: power number [-], V: volume [L])
As for Np: power number, 10 L reaction tank, 1.1 L reaction tank for paddle blade, and 1.8 for paddle blade were used. For other parameters, ρ: density is 1.22 g / cc, d: blade span is 10 L reaction tank, paddle blade is 128 mm, 1 L reaction tank, paddle blade is 80 mm, V: volume is 10 L reaction tank → 5 L ( Example 3) 1L reaction vessel → 0.7L (Examples 1 and 4 and Comparative Examples 2 and 3) and 0.3L (Comparative Example 4) were used.
　実施例１
　内容積１Ｌの反応容器に純水３００ｇを収め、これを４０℃まで昇温、維持した。別に、硫酸マンガンを純水に溶解し、０．８２ｍｏｌ／Ｌの硫酸マンガンを含む金属塩水溶液を調製した。金属塩水溶液のアルカリ土類濃度はＣａ１０ｐｐｍ、Ｍｇ７ｐｐｍ、その他のアルカリ土類金属は検出限界以下であった。当該金属塩水溶液を供給速度１０ｇ／ｍｉｎで反応容器に添加した。同時に、酸化剤として３５％過酸化水素水を供給速度５．４ｇ／ｍｉｎで反応容器中に添加した。なお、混合においては外径８０ｍｍの４枚羽根のパドル翼を用いて６００ｐｐｍで回転させた。その際の攪拌所要動力は１０ｋＷ／ｍ３であった。また、酸化還元電位が飽和カロメル電極基準で－０．０５５Ｖとなるように、５ｍｏｌ／Ｌの水酸化カリウム水溶液（アルカリ金属水溶液）を連続的に３０分添加した。金属塩水溶液及び３５％過酸化水素水供給の際の、Ｋ／Ｍｎモル比は４．７であった。上記操作により層状マンガン酸化物が析出したスラリーを得た。スラリーの固形分濃度は２．８ｗｔ％であった。得られたスラリーをろ過し、純水で洗浄した後、洗浄後のウェットケーキを６０℃で５時間乾燥して熱硬化させることで、層状マンガン酸化物（Ｋ０．３４ＭｎＯ２）の塊状凝集物を得た。塊状凝集物をアルミナ製乳鉢と乳棒でタッピングすることで解砕した。その後、目開き０．６ｍｍのメッシュを通し、目開き０．３ｍｍのメッシュの上に残ったものを採取することで、０．３～０．６ｍｍに分級し、層状マンガン酸化物成形体を得た。 Example 1
300 g of pure water was placed in a reaction vessel having an internal volume of 1 L, and the temperature was raised and maintained at 40 ° C. Separately, manganese sulfate was dissolved in pure water to prepare a metal salt aqueous solution containing 0.82 mol / L manganese sulfate. The alkaline earth concentration of the metal salt aqueous solution was Ca 10 ppm, Mg 7 ppm, and other alkaline earth metals were below the detection limit. The metal salt aqueous solution was added to the reaction vessel at a supply rate of 10 g / min. At the same time, 35% hydrogen peroxide solution was added as an oxidizing agent into the reaction vessel at a supply rate of 5.4 g / min. In the mixing, a 4-blade paddle blade having an outer diameter of 80 mm was used and rotated at 600 ppm. The power required for stirring at that time was 10 kW / m 3 . Further, a 5 mol / L potassium hydroxide aqueous solution (alkali metal aqueous solution) was continuously added for 30 minutes so that the redox potential was −0.055 V based on the saturated calomel electrode. The K / Mn molar ratio was 4.7 when the metal salt aqueous solution and the 35% hydrogen peroxide solution were supplied. By the above operation, a slurry in which layered manganese oxide was precipitated was obtained. The solid content concentration of the slurry was 2.8 wt%. The obtained slurry is filtered, washed with pure water, and then the washed wet cake is dried at 60 ° C. for 5 hours and thermoset to cause agglomerates of layered manganese oxide (K 0.34 MnO 2). I got something. The lumpy agglomerates were crushed by tapping with an alumina mortar and pestle. After that, it is passed through a mesh with a mesh opening of 0.6 mm, and what remains on the mesh with a mesh opening of 0.3 mm is collected to classify the product into 0.3 to 0.6 mm to obtain a layered manganese oxide molded product. It was.
　得られた層状マンガン酸化物成形体は、粉末Ｘ線回折の測定により層状結晶構造を有することがわかり、層間にカリウムイオンが存在するバーネサイト型の結晶構造に由来する回折パターンと一致した。層間距離は７．１２オングストローム、六方晶に帰属したときの００１ピークのＦＷＨＭは１．５００°であった。元素組成の測定によるＫ／Ｍｎモル比は０．３４であった。 The obtained layered manganese oxide molded product was found to have a layered crystal structure by measurement of powder X-ray diffraction, and was consistent with a diffraction pattern derived from a burnesite-type crystal structure in which potassium ions were present between layers. The interlayer distance was 7.12 angstroms, and the FWHM of the 001 peak when it was assigned to the hexagonal crystal was 1.500 °. The K / Mn molar ratio measured by elemental composition was 0.34.
　得られた層状マンガン酸化物成形体のかさ密度は１．１８ｇ／ｃｍ３であり、圧壊強度は２３３９ｍＮ、撹拌摩耗度は２．１５重量％であった。なお、撹拌摩耗度の測定前後における層状マンガン酸化物成形体の形状変化はなかった。また、成形体のケイ素、アルミニウム、チタン及びジルコニウム濃度はＩＣＰ測定の結果、検出限界以下、炭素濃度は検出限界以下（３０００ｐｐｍ以下）であった。また、模擬海水Ａ、Ｂ、Ｃを用いたストロンチウム吸着試験を行った。処理液Ａ、Ｂ、ＣのＩＣＰ測定の結果、Ｃ／Ｃ０＝０．１となるまでの破過Ｂ．Ｖ．値はそれぞれ４６００、６８０、８３４０であった。 The bulk density of the obtained layered manganese oxide molded product was 1.18 g / cm 3 , the crushing strength was 2339 mN, and the degree of agitation wear was 2.15% by weight. There was no change in the shape of the layered manganese oxide molded product before and after the measurement of the degree of stirring wear. As a result of ICP measurement, the silicon, aluminum, titanium and zirconium concentrations of the molded product were below the detection limit, and the carbon concentration was below the detection limit (3000 ppm or less). In addition, a strontium adsorption test using simulated seawater A, B, and C was performed. Breakthrough B. until C / C 0 = 0.1 as a result of ICP measurement of the treatment liquids A, B and C. V. The values were 4600, 680 and 8340, respectively.
　当該層状マンガン酸化物成形体の測定結果を表１に示す。また、当該層状マンガン酸化物の粉末Ｘ線回折パターンを図１に示し、当該層状マンガン酸化物の走査電子顕微鏡像（ＳＥＭ像）を図２に示す。 Table 1 shows the measurement results of the layered manganese oxide molded product. Further, the powder X-ray diffraction pattern of the layered manganese oxide is shown in FIG. 1, and the scanning electron microscope image (SEM image) of the layered manganese oxide is shown in FIG.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　実施例２
　硝酸マンガン六水和物（関東化学特級、９８％）、５２．８３ｇを、少量の水に溶解させ、メスフラスコを用いて、０．３ｍｏｌ／Ｌとなるように６００ｍＬにメスアップすることで硝酸マンガン水溶液を調製した。水酸化カリウム（ＫＯＨ）４７．６１ｇを少量の水に溶解させ、そこに、過酸化水素水（Ｈ２Ｏ２、３５％）５１．６０ｍＬを加えた（Ｈ２Ｏ２＋ＫＯＨ水溶液）。メスフラスコを用いて６００ｍＬに調製した。この際のＫＯＨ濃度は１．２ｍｏｌ／Ｌ、Ｈ２Ｏ２濃度は１．０ｍｏｌ／Ｌであった。 Example 2
Manganese nitrate hexahydrate (Kanto Chemical Co., Ltd., 98%), 52.83 g, is dissolved in a small amount of water, and a volumetric flask is used to increase the volume to 600 mL to 0.3 mol / L to produce manganese nitrate. An aqueous manganese solution was prepared. 47.61 g of potassium hydroxide (KOH) was dissolved in a small amount of water, and 51.60 mL of hydrogen peroxide solution (H 2 O 2 , 35%) was added thereto (H 2 O 2 + KOH aqueous solution). It was prepared to 600 mL using a volumetric flask. At this time, the KOH concentration was 1.2 mol / L and the H 2 O 2 concentration was 1.0 mol / L.
　６００ｍＬの硝酸マンガン水溶液を２０００ｍＬのビーカーに移し、そこにマグネティックスターラーを用いて撹拌しながらＨ２Ｏ２＋ＫＯＨ水溶液６００ｍＬをゆっくりと加えた。１０分間撹拌した後、撹拌を止めて１時間静置し、得られた固体をろ紙を用いて減圧ろ過し、３０００ｍＬの水で洗浄を行って、乾燥機中、６０℃で１日間乾燥させることにより熱硬化させた。乾燥物は光沢を帯びた塊状凝集物であり、収量は２１．１２ｇであった。 A 600 mL aqueous manganese nitrate solution was transferred to a 2000 mL beaker, and 600 mL of an H 2 O 2 + KOH aqueous solution was slowly added thereto with stirring using a magnetic stirrer. After stirring for 10 minutes, the stirring is stopped and the mixture is allowed to stand for 1 hour, the obtained solid is filtered under reduced pressure using a filter paper, washed with 3000 mL of water, and dried in a dryer at 60 ° C. for 1 day. Heat-cured with. The dried product was a glossy lumpy aggregate, and the yield was 21.12 g.
　当該塊状凝集物をアルミナ乳鉢に入れ、乳棒で解砕した。解砕後の破砕片を開き０．６ｍｍのメッシュを通し、目開き０．３ｍｍのメッシュの上に残ったものを採取することで、０．３～０．６ｍｍに分級し、層状マンガン酸化物成形体を得た。 The lumpy agglomerate was placed in an alumina mortar and crushed with a pestle. The crushed pieces after crushing are opened, passed through a 0.6 mm mesh, and the residue remaining on the mesh with a mesh opening of 0.3 mm is collected to classify the crushed pieces into 0.3 to 0.6 mm and layered manganese oxide. A molded product was obtained.
　また、ろ過洗浄後、得られた湿潤試料Ａおよび６０℃で一日間熱硬化した試料Ｂの粉末Ｘ線回折パターンを図３に示す。試料Ａは層間距離９．３７オングストロームのブセライト、試料Ｂは層間距離７．０９オングストロームのバーネサイトに帰属できる。また、００１ピークのＦＷＨＭは１．２１２°であった。したがって、硝酸マンガン、過酸化水素水、ＫＯＨ混合水溶液中で析出させる工程においては、析出物質は層間距離９オングストローム以上１０オングストローム未満のブセライトであって、熱硬化過程で層間距離７オングストロームのバーネサイトに変化することが確認された。 FIG. 3 shows the powder X-ray diffraction patterns of the wet sample A obtained after filtration and cleaning and the sample B thermoset at 60 ° C. for one day. Sample A can be attributed to buserite with an interlayer distance of 9.37 angstroms, and sample B can be attributed to burnesite with an interlayer distance of 7.09 angstroms. The FWHM of the 001 peak was 1.212 °. Therefore, in the step of precipitating in a mixed aqueous solution of manganese nitrate, hydrogen peroxide solution, and KOH, the precipitated substance is bucelite having an interlayer distance of 9 angstroms or more and less than 10 angstroms, and changes to burnesite having an interlayer distance of 7 angstroms in the heat curing process. It was confirmed that
　得られた層状マンガン酸化物成形体の、かさ密度は１．１９ｇ／ｃｍ３であり、圧壊強度は３４２６ｍＮ、撹拌摩耗度は２．８７重量％であった。なお、撹拌摩耗度の測定前後における層状マンガン酸化物成形体の形状変化はなかった。また、成形体のケイ素、アルミニウム、チタン及びジルコニウム濃度はＩＣＰ測定の結果、検出限界以下であり、炭素濃度は検出限界以下（３０００ｐｐｍ以下）であった。また、処理液Ａを用いたストロンチウム吸着試験における破過Ｂ．Ｖ．値は５１０５であった。 The obtained layered manganese oxide molded product had a bulk density of 1.19 g / cm 3 , a crushing strength of 3426 mN, and a stirring wear degree of 2.87% by weight. There was no change in the shape of the layered manganese oxide molded product before and after the measurement of the degree of stirring wear. As a result of ICP measurement, the silicon, aluminum, titanium and zirconium concentrations of the molded product were below the detection limit, and the carbon concentration was below the detection limit (3000 ppm or less). In addition, the rupture B. in the strontium adsorption test using the treatment liquid A. V. The value was 5105.
　当該層状マンガン酸化物成形体の測定結果を表１に示す。また、当該層状マンガン酸化物の走査電子顕微鏡像（ＳＥＭ像）を図４に示す。 Table 1 shows the measurement results of the layered manganese oxide molded product. Further, a scanning electron microscope image (SEM image) of the layered manganese oxide is shown in FIG.
　実施例３
　内容積１０Ｌの反応容器に純水２８００ｇを収め、これを６０℃まで昇温、維持した。別に、硫酸マンガンを純水に溶解し、２．０ｍｏｌ／Ｌの硫酸マンガンを含む金属塩水溶液を調製した。金属塩水溶液のアルカリ土類濃度はＣａ２２ｐｐｍ、Ｍｇ１５ｐｐｍ、その他のアルカリ土類金属は検出限界以下であった。当該金属塩水溶液を供給速度３５ｇ／ｍｉｎで反応容器に添加した。同時に、酸化剤として３５％過酸化水素水を供給速度１３ｇ／ｍｉｎで反応容器中に添加した。金属塩水溶液及び３５％過酸化水素水供給の際に、Ｋ／Ｍｎモル比は４．０となるように５．０ｍｏｌ／Ｌの水酸化カリウム水溶液を同時滴下した。なお、混合においては外径８０ｍｍの４枚羽根のパドル翼を用いて６００ｐｐｍで回転させた。その際の攪拌所要動力は１０ｋＷ／ｍ３であった。また、酸化還元電位が飽和カロメル電極基準で－０．０６２Ｖであった。上記操作により層状マンガン酸化物が析出したスラリーを得た。スラリーの固形分濃度は２．８ｗｔ％であった。得られたスラリーをろ過し、純水で洗浄した後、洗浄後のウェットケーキを６０℃で５時間乾燥して熱硬化させることで、層状マンガン酸化物（Ｋ０．３５ＭｎＯ２）の塊状凝集物を得た。塊状凝集物をアルミナ製乳鉢と乳棒でタッピングすることで解砕した。その後、目開き０．６ｍｍのメッシュを通し、目開き０．３ｍｍのメッシュの上に残ったものを採取することで、０．３～０．６ｍｍに分級し、層状マンガン酸化物成形体を得た。 Example 3
2800 g of pure water was placed in a reaction vessel having an internal volume of 10 L, and the temperature was raised and maintained at 60 ° C. Separately, manganese sulfate was dissolved in pure water to prepare a metal salt aqueous solution containing 2.0 mol / L manganese sulfate. The alkaline earth concentration of the metal salt aqueous solution was Ca 22 ppm, Mg 15 ppm, and other alkaline earth metals were below the detection limit. The metal salt aqueous solution was added to the reaction vessel at a supply rate of 35 g / min. At the same time, 35% hydrogen peroxide solution was added into the reaction vessel as an oxidizing agent at a supply rate of 13 g / min. When the metal salt aqueous solution and the 35% hydrogen peroxide solution were supplied, a 5.0 mol / L potassium hydroxide aqueous solution was simultaneously added dropwise so that the K / Mn molar ratio was 4.0. In the mixing, a 4-blade paddle blade having an outer diameter of 80 mm was used and rotated at 600 ppm. The power required for stirring at that time was 10 kW / m 3 . The redox potential was −0.062V based on the saturated calomel electrode. By the above operation, a slurry in which layered manganese oxide was precipitated was obtained. The solid content concentration of the slurry was 2.8 wt%. The obtained slurry is filtered, washed with pure water, and then the washed wet cake is dried at 60 ° C. for 5 hours and thermoset to cause agglomerates of layered manganese oxide (K 0.35 MnO 2). I got something. The lumpy agglomerates were crushed by tapping with an alumina mortar and pestle. After that, a mesh with a mesh opening of 0.6 mm is passed through, and what remains on the mesh with a mesh opening of 0.3 mm is collected to classify the mixture into 0.3 to 0.6 mm to obtain a layered manganese oxide molded product. It was.
　得られた層状マンガン酸化物成形体は、粉末Ｘ線回折の測定により、僅かに副生相を含むが、層間にカリウムイオンが存在するバーネサイト型酸化物が主相であることが判明した。層間距離は７．０９オングストローム、六方晶に帰属したときの００１ピークのＦＷＨＭは１．１６７°であった。元素組成の測定によるＫ／Ｍｎモル比は０．３５であった。 The obtained layered manganese oxide molded product contained a slight by-product phase by powder X-ray diffraction measurement, but it was found that the main phase was a burnesite-type oxide in which potassium ions were present between layers. The interlayer distance was 7.09 angstroms, and the FWHM of the 001 peak when it was assigned to the hexagonal crystal was 1.167 °. The K / Mn molar ratio measured by elemental composition was 0.35.
　得られた層状マンガン酸化物成形体のかさ密度は１．３９ｇ／ｃｍ３であり、圧壊強度は１５９１ｍＮ、撹拌摩耗度は４．０２重量％であった。なお、撹拌摩耗度の測定前後における層状マンガン酸化物成形体の形状変化はなかった。また、成形体のケイ素、アルミニウム、チタン及びジルコニウム濃度はＩＣＰ測定の結果、検出限界以下、炭素濃度は検出限界以下（３０００ｐｐｍ以下）であった。また、模擬海水Ｂを用いたストロンチウム吸着試験を行った。処理液ＢのＩＣＰ測定の結果、Ｃ／Ｃ０＝０．１となるまでの破過Ｂ．Ｖ．値は２０００であった。 The bulk density of the obtained layered manganese oxide molded product was 1.39 g / cm 3 , the crushing strength was 1591 mN, and the degree of agitation wear was 4.02% by weight. There was no change in the shape of the layered manganese oxide molded product before and after the measurement of the degree of stirring wear. As a result of ICP measurement, the silicon, aluminum, titanium and zirconium concentrations of the molded product were below the detection limit, and the carbon concentration was below the detection limit (3000 ppm or less). In addition, a strontium adsorption test was conducted using simulated seawater B. Breakthrough until C / C 0 = 0.1 as a result of ICP measurement of the treatment liquid B. V. The value was 2000.
　当該層状マンガン酸化物成形体の測定結果を表１に示す。また、当該層状マンガン酸化物の粉末Ｘ線回折パターンを図５に示し、当該層状マンガン酸化物の走査電子顕微鏡像（ＳＥＭ像）を図６に示す。 Table 1 shows the measurement results of the layered manganese oxide molded product. The powder X-ray diffraction pattern of the layered manganese oxide is shown in FIG. 5, and the scanning electron microscope image (SEM image) of the layered manganese oxide is shown in FIG.
　実施例４
　容器上部に抜き出し口を持つ内容積１Ｌの反応容器に純水８００ｇを収め、これを６０℃まで昇温、維持した。別に、硫酸マンガンを純水に溶解し、０．９０ｍｏｌ／Ｌの硫酸マンガンを含む金属塩水溶液を調製した。当該金属塩水溶液を供給速度１０ｇ／ｍｉｎで反応容器に添加した。同時に、２．３ｍｏｌ／Ｌ水酸化カリウム水溶液（アルカリ金属水溶液）を調製し、１９ｇ／ｍｉｎで反応容器に添加した。さらに、酸化剤として１０％ペルオキソ二硫酸ナトリウム水溶液を調製し、金属塩水溶液やアルカリ金属水溶液と同時に供給速度１８ｇ／ｍｉｎで反応容器中に添加した。なお、混合の際の体積当たりの攪拌動力は１０ｋＷ／ｍ３であった。上記操作を４時間にわたり連続的に行った。層状マンガン酸化物が析出したスラリーが容器上部の抜き出し口から連続的に流れ出た。流れ出たスラリーは４０分毎にサンプリングを行った。実験開始２００分から２４０分に流れ出たスラリーの固形分濃度は１．８ｗｔ％であった。得られたスラリーをろ過し、純水で洗浄した後、洗浄後のウェットケーキを６０℃で５時間乾燥して熱硬化させることで、層状マンガン酸化物（Ｎａ０．２５Ｋ０．２３ＭｎＯ２）の塊状凝集物を得た。塊状凝集物をアルミナ製乳鉢と乳棒でタッピングすることで解砕した。その後、目開き０．６ｍｍのメッシュを通し、目開き０．３ｍｍのメッシュの上に残ったものを採取することで、０．３～０．６ｍｍに分級し、層状マンガン酸化物成形体を得た。 Example 4
800 g of pure water was placed in a reaction vessel having an internal volume of 1 L having an extraction port at the top of the vessel, and the temperature was raised and maintained at 60 ° C. Separately, manganese sulfate was dissolved in pure water to prepare a metal salt aqueous solution containing 0.90 mol / L manganese sulfate. The metal salt aqueous solution was added to the reaction vessel at a supply rate of 10 g / min. At the same time, a 2.3 mol / L potassium hydroxide aqueous solution (alkali metal aqueous solution) was prepared and added to the reaction vessel at 19 g / min. Further, a 10% aqueous solution of sodium peroxodisulfate was prepared as an oxidizing agent and added to the reaction vessel at a supply rate of 18 g / min at the same time as the aqueous metal salt solution and the aqueous alkali metal solution. The stirring power per volume at the time of mixing was 10 kW / m 3 . The above operation was continuously performed for 4 hours. The slurry in which the layered manganese oxide was precipitated continuously flowed out from the extraction port at the top of the container. The slurry that flowed out was sampled every 40 minutes. The solid content concentration of the slurry that flowed out from 200 minutes to 240 minutes after the start of the experiment was 1.8 wt%. The resulting slurry was filtered, washed with pure water, the wet cake after washing was dried 5 hours at 60 ° C. By thermally curing, layered manganese oxide (Na 0.25 K 0.23 MnO 2 ) Was obtained. The lumpy agglomerates were crushed by tapping with an alumina mortar and pestle. After that, a mesh with a mesh opening of 0.6 mm is passed through, and what remains on the mesh with a mesh opening of 0.3 mm is collected to classify the mixture into 0.3 to 0.6 mm to obtain a layered manganese oxide molded product. It was.
　得られた層状マンガン酸化物成形体は、粉末Ｘ線回折の測定により層状結晶構造を有することがわかり、層間にカリウムイオンが存在するバーネサイト型の結晶構造に由来する回折パターンと一致した。層間距離は７．１８オングストローム、六方晶に帰属したときの００１ピークのＦＷＨＭは３．２１０°であった。元素組成の測定によるＮａ／Ｍｎモル比は０．２５、Ｋ／Ｍｎモル比は０．２３であった。 The obtained layered manganese oxide molded product was found to have a layered crystal structure by measurement of powder X-ray diffraction, and was consistent with a diffraction pattern derived from a burnesite-type crystal structure in which potassium ions were present between layers. The interlayer distance was 7.18 angstroms, and the FWHM of the 001 peak when it was assigned to the hexagonal crystal was 3.210 °. The Na / Mn molar ratio was 0.25 and the K / Mn molar ratio was 0.23 as measured by the element composition.
　得られた層状マンガン酸化物成形体のかさ密度は１．３３ｇ／ｃｍ３であり、圧壊強度は２０６９ｍＮ、撹拌摩耗度は０．０５重量％であった。なお、撹拌摩耗度の測定前後における層状マンガン酸化物成形体の形状変化はなかった。また、成形体のケイ素、アルミニウム、チタン及びジルコニウム濃度はＩＣＰ測定の結果、検出限界以下、炭素濃度は検出限界以下（３０００ｐｐｍ以下）であった。また、模擬海水Ａ、Ｃを用いたストロンチウム吸着試験を行った。処理液Ａ、ＣのＩＣＰ測定の結果、Ｃ／Ｃ０＝０．１となるまでの破過Ｂ．Ｖ．値はそれぞれ４２６０、９２００であった。 The bulk density of the obtained layered manganese oxide molded product was 1.33 g / cm 3 , the crushing strength was 2069 mN, and the degree of agitation wear was 0.05% by weight. There was no change in the shape of the layered manganese oxide molded product before and after the measurement of the degree of stirring wear. As a result of ICP measurement, the silicon, aluminum, titanium and zirconium concentrations of the molded product were below the detection limit, and the carbon concentration was below the detection limit (3000 ppm or less). In addition, a strontium adsorption test was conducted using simulated seawaters A and C. Breakthrough until C / C 0 = 0.1 as a result of ICP measurement of the treatment liquids A and C. V. The values were 4260 and 9200, respectively.
　当該層状マンガン酸化物成形体の測定結果を表１に示す。また、当該層状マンガン酸化物の粉末Ｘ線回折パターンを図７に示し、当該層状マンガン酸化物の走査電子顕微鏡像（ＳＥＭ像）を図８に示す。 Table 1 shows the measurement results of the layered manganese oxide molded product. The powder X-ray diffraction pattern of the layered manganese oxide is shown in FIG. 7, and the scanning electron microscope image (SEM image) of the layered manganese oxide is shown in FIG.
　比較例１
　炭酸カリウム（特級試薬、キシダ化学製）と炭酸マンガン（Ｌｉａｎｙｕｎｇａｎｇ　Ｄｏｎｇｄｕ　Ｃｈｅｍｉｃａｌ　Ｃｏ．，Ｌｔｄ．製）をＫ／Ｍｎモル比１．０となるよう秤量し乾式ボールミル混合を行い、混合粉をマッフル炉で空気流通下３００℃、１２時間、次いで４００℃で６時間焼成を行った。該焼成品を５倍量の水にて水洗ろ過し、６０℃にて一晩乾燥し、乾式粉砕機（フォースミル、大阪ケミカル製）にて粗粒を粉砕し、カリウム型層状マンガン酸化物を得た。得られたカリウム型層状マンガン酸化物は、粉末Ｘ線回折の測定により層状結晶構造を有することがわかり、層間にカリウムイオンが存在するバーネサイト型の結晶構造に由来する回折パターンと一致した。層間距離は７．１４オングストローム、六方晶に帰属したときの００１ピークのＦＷＨＭは０．５７７°、元素組成から求めたＫ／Ｍｎモル比は０．３０７であった。 Comparative Example 1
Potassium carbonate (special grade reagent, manufactured by Kishida Chemical Co., Ltd.) and manganese carbonate (manufactured by Lianyungang Dongdu Chemical Co., Ltd.) are weighed so as to have a K / Mn molar ratio of 1.0, mixed with a dry ball mill, and the mixed powder is mixed in a muffle furnace. Baking was carried out at 300 ° C. for 12 hours and then at 400 ° C. for 6 hours under air flow. The fired product was washed with 5 times the amount of water, filtered, dried at 60 ° C. overnight, and coarse grains were crushed with a dry crusher (Force Mill, manufactured by Osaka Chemical) to obtain potassium-type layered manganese oxide. Obtained. The obtained potassium-type layered manganese oxide was found to have a layered crystal structure by measurement of powder X-ray diffraction, and was consistent with the diffraction pattern derived from the burnesite-type crystal structure in which potassium ions were present between layers. The interlayer distance was 7.14 angstroms, the FWHM of the 001 peak when assigned to hexagonal crystals was 0.577 °, and the K / Mn molar ratio determined from the elemental composition was 0.307.
　次に、得られたカリウム型層状マンガン酸化物、シリカゾル及びカルボキシメチルセルロース（ＣＭＣ）を以下の重量割合となるように混合し、混合物を得た。 Next, the obtained potassium-type layered manganese oxide, silica sol and carboxymethyl cellulose (CMC) were mixed so as to have the following weight ratios to obtain a mixture.
　　カリウム型層状マンガン酸化物：１００重量部
　　シリカゾル中のシリカ：１６重量部
　　水：３６重量部
　　ＣＭＣ：５重量部
　無機結合剤としてのシリカゾルは、ゾル濃度４８重量％及びゾル中のシリカ粒子の平均粒子径平均ゾル粒径０．０２μｍのシリカゾル（商品名：スノーテックス５０－Ｔ、日産化学工業製）を使用した。また、成形助剤としてＣＭＣ（商品名：セロゲンＷＳ－Ｄ、第一工業製薬製）を使用した。 Potassium-type layered manganese oxide: 100 parts by weight Silica in silica sol: 16 parts by weight Water: 36 parts by weight CMC: 5 parts by weight Silica sol as an inorganic binder has a sol concentration of 48% by weight and average particles of silica particles in the sol. A silica sol (trade name: Snowtex 50-T, manufactured by Nissan Chemical Industries, Ltd.) having a diameter average sol particle size of 0.02 μm was used. Further, CMC (trade name: Cellogen WS-D, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was used as a molding aid.
　得られた混合物はヘンシェルミキサーで２０分間混合した後、押出し成形して、直径１．５ｍｍの円柱状の成形体を得た。得られた成形体を２５Ｌ／ｍｉｎの空気流通下で、５００℃、３時間焼成した後、解砕し、開き０．６ｍｍのメッシュを通し、目開き０．３ｍｍのメッシュの上に残ったものを採取することで、０．３～０．６ｍｍに分級し、層状マンガン酸化物成形体を得た。 The obtained mixture was mixed with a Henschel mixer for 20 minutes and then extruded to obtain a cylindrical molded body having a diameter of 1.5 mm. The obtained molded product was fired at 500 ° C. for 3 hours under an air flow of 25 L / min, crushed, passed through a mesh having an opening of 0.6 mm, and remained on a mesh having an opening of 0.3 mm. Was collected and classified into 0.3 to 0.6 mm to obtain a layered manganese oxide molded product.
　得られた層状マンガン酸化物成形体の、かさ密度は０．７７１ｇ／ｃｍ３であり、圧壊強度は４８３ｍＮ、撹拌摩耗度は３１．０重量％であった。なお、撹拌摩耗度の測定前後における層状マンガン酸化物成形体の形状変化はなかった。また、成形体のケイ素、アルミニウム、チタン及びジルコニウム濃度はＩＣＰ測定の結果、ケイ素が６．４ｗｔ％となった。炭素濃度は検出限界以下（３０００ｐｐｍ以下）であった。また、処理液Ａ、Ｂを用いたストロンチウム吸着試験における破過Ｂ．Ｖ．値はそれぞれ２５６０、１２１０であった。 The obtained layered manganese oxide molded product had a bulk density of 0.771 g / cm 3 , a crushing strength of 483 mN, and a stirring wear degree of 31.0% by weight. There was no change in the shape of the layered manganese oxide molded product before and after the measurement of the degree of stirring wear. As a result of ICP measurement, the concentrations of silicon, aluminum, titanium and zirconium in the molded product were 6.4 wt% of silicon. The carbon concentration was below the detection limit (3000 ppm or less). In addition, the rupture B. in the strontium adsorption test using the treatment liquids A and B. V. The values were 2560 and 1210, respectively.
　当該層状マンガン酸化物成形体の測定結果を表１に示す。また、当該層状マンガン酸化物の粉末Ｘ線回折パターンを図９に示し、当該層状マンガン酸化物の走査電子顕微鏡像（ＳＥＭ像）を図１０に示す。 Table 1 shows the measurement results of the layered manganese oxide molded product. Further, the powder X-ray diffraction pattern of the layered manganese oxide is shown in FIG. 9, and the scanning electron microscope image (SEM image) of the layered manganese oxide is shown in FIG.
　比較例２
　内容積１Ｌの反応容器に純水３００ｇを収め、これを４０℃まで昇温、維持した。工業用でアルカリ土類金属分を含む硫酸マンガン（硫酸マンガン濃度０．８２ｍｏｌ／Ｌ）を含む金属塩水溶液を使用した。金属塩水溶液中のアルカリ土類金属濃度はＣａ５００ｐｐｍ、Ｍｇ１４００ｐｐｍ、その他のアルカリ土類金属は検出限界以下であった。硫酸マンガン水溶液のアルカリ土類金属濃度が異なること以外は実施例１と同様に合成を行った。 Comparative Example 2
300 g of pure water was placed in a reaction vessel having an internal volume of 1 L, and the temperature was raised and maintained at 40 ° C. An aqueous metal salt solution containing manganese sulfate (manganese sulfate concentration 0.82 mol / L) containing an alkaline earth metal component for industrial use was used. The alkaline earth metal concentration in the metal salt aqueous solution was Ca 500 ppm, Mg 1400 ppm, and other alkaline earth metals were below the detection limit. Synthesis was carried out in the same manner as in Example 1 except that the alkaline earth metal concentrations of the manganese sulfate aqueous solution were different.
　ろ過洗浄後の乾燥試料の粉末Ｘ線回折パターンを図１１に示す。層状構造を示す低角度の００１ピークはほとんどみられなかったことから、当該マンガン酸化物は層状マンガン酸化物ではないことが分かった。 FIG. 11 shows a powder X-ray diffraction pattern of the dried sample after filtration and cleaning. Since almost no low-angle 001 peak showing a layered structure was observed, it was found that the manganese oxide was not a layered manganese oxide.
　当該マンガン酸化物成形体の測定結果を表１に示す。 Table 1 shows the measurement results of the manganese oxide molded product.
　比較例３
　攪拌翼の回転速度を１００ｒｐｍに低下させ、攪拌所要動力を０．４ｋＷ／ｍ３とした以外は実施例１と同様に合成を行った。 Comparative Example 3
The synthesis was carried out in the same manner as in Example 1 except that the rotation speed of the stirring blade was reduced to 100 rpm and the required power for stirring was set to 0.4 kW / m 3.
　その結果、緻密で固い塊状凝集物は得られず、吸着試験に成形体として供することは不可能であった。また、ろ過洗浄後の乾燥試料の粉末Ｘ線回折パターンを図１２に示す。層間にカリウムイオンが存在するバーネサイト型の層状マンガン酸化物の他に、ＭｎＯＯＨ及びＭｎ３Ｏ４のピークが強く観測されたことから、試料はこれらの混合相であることが確認された。 As a result, a dense and hard agglomerate was not obtained, and it was impossible to use it as a molded product in an adsorption test. Further, FIG. 12 shows a powder X-ray diffraction pattern of the dried sample after filtration and cleaning. Other birnessite type layered manganese oxide present potassium ions between layers, because the peak of MnOOH and Mn 3 O 4 is strongly observed, the sample was confirmed to be a mixture of these phases.
　当該層状マンガン酸化物の測定結果を表１に示す。 Table 1 shows the measurement results of the layered manganese oxide.
　比較例４
　内容積１Ｌの反応容器に純水１００ｇを収め、これを４０℃まで昇温、維持した。別に、硫酸マンガンを純水に溶解し、２．０ｍｏｌ／Ｌの硫酸マンガンを含む金属塩水溶液を調製した。当該金属塩水溶液を供給速度５ｇ／ｍｉｎで反応容器に添加した。同時に、１０ｍｏｌ／Ｌの水酸化カリウム水溶液（アルカリ金属水溶液）を供給速度３．３ｇ／ｍｉｎ、酸化剤として３５％過酸化水素水を供給速度１．６ｇ／ｍｉｎで反応容器中に添加した。金属塩水溶液及び３５％過酸化水素水供給の際の、Ｋ／Ｍｎモル比は３．０であった。なお、混合の際の体積当たりの攪拌動力は２３ｋＷ／ｍ３であった。また、上記操作により層状マンガン酸化物が析出したスラリーを得た。スラリーの固形分濃度は６．２ｗｔ％であった。得られたスラリーをろ過し、純水で洗浄した後、洗浄後のウェットケーキを６０℃で５時間乾燥して熱硬化させることで、層状マンガン酸化物（Ｋ０．２９ＭｎＯ２）の塊状凝集物を得た。塊状凝集物をアルミナ製乳鉢と乳棒でタッピングすることで解砕した。その後、目開き０．６ｍｍのメッシュを通し、目開き０．３ｍｍのメッシュの上に残ったものを採取することで、０．３～０．６ｍｍに分級し、層状マンガン酸化物成形体を得た。 Comparative Example 4
100 g of pure water was placed in a reaction vessel having an internal volume of 1 L, and the temperature was raised and maintained at 40 ° C. Separately, manganese sulfate was dissolved in pure water to prepare a metal salt aqueous solution containing 2.0 mol / L manganese sulfate. The metal salt aqueous solution was added to the reaction vessel at a supply rate of 5 g / min. At the same time, a 10 mol / L potassium hydroxide aqueous solution (alkali metal aqueous solution) was added into the reaction vessel at a supply rate of 3.3 g / min, and a 35% hydrogen peroxide solution as an oxidizing agent was added at a supply rate of 1.6 g / min. The K / Mn molar ratio was 3.0 when the metal salt aqueous solution and the 35% hydrogen peroxide solution were supplied. The stirring power per volume at the time of mixing was 23 kW / m 3 . In addition, a slurry in which layered manganese oxide was precipitated was obtained by the above operation. The solid content concentration of the slurry was 6.2 wt%. The obtained slurry is filtered, washed with pure water, and then the washed wet cake is dried at 60 ° C. for 5 hours and thermoset to cause agglomerates of layered manganese oxide (K 0.29 MnO 2). I got something. The lumpy agglomerates were crushed by tapping with an alumina mortar and pestle. After that, a mesh with a mesh opening of 0.6 mm is passed through, and what remains on the mesh with a mesh opening of 0.3 mm is collected to classify the mixture into 0.3 to 0.6 mm to obtain a layered manganese oxide molded product. It was.
　得られた層状マンガン酸化物成形体は、粉末Ｘ線回折の測定により層状結晶構造を有することがわかり、層間にカリウムイオンが存在するバーネサイト型の結晶構造に由来する回折パターンと一致した。層間距離は７．１２オングストローム、六方晶に帰属したときの００１ピークのＦＷＨＭは１．４４０°であった。元素組成の測定によるＫ／Ｍｎモル比は０．３４であった。 The obtained layered manganese oxide molded product was found to have a layered crystal structure by measurement of powder X-ray diffraction, and was consistent with a diffraction pattern derived from a burnesite-type crystal structure in which potassium ions were present between layers. The interlayer distance was 7.12 angstroms, and the FWHM of the 001 peak when it was assigned to the hexagonal crystal was 1.440 °. The K / Mn molar ratio measured by elemental composition was 0.34.
　得られた層状マンガン酸化物成形体のかさ密度は０．３６０ｇ／ｃｍ３と著しく低くかつ脆かったため、吸着試験に供することは困難であった。 Since the bulk density of the obtained layered manganese oxide molded product was extremely low at 0.360 g / cm 3 and brittle, it was difficult to use it for an adsorption test.
　当該層状マンガン酸化物成形体の測定結果を表１に示す。 Table 1 shows the measurement results of the layered manganese oxide molded product.
　なお、２０１９年１２月６日に出願された日本国特許出願２０１９－２２０９２８号の明細書、特許請求の範囲、図面及び要約書の全内容をここに引用し、本発明の明細書の開示として、取り入れるものである。 The entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2019-220928 filed on December 6, 2019 are cited here as disclosure of the specification of the present invention. , Incorporate.
　本発明の層状マンガン酸化物成形体はストロンチウムの吸着剤として使用できる。特に、ウラン核***型原子炉由来の放射性核種を含む海水のような、多量の共存陽イオンを含む処理水から、ストロンチウムイオンを選択吸着する吸着剤として使用可能である。 The layered manganese oxide molded product of the present invention can be used as an adsorbent for strontium. In particular, it can be used as an adsorbent for selectively adsorbing strontium ions from treated water containing a large amount of coexisting cations, such as seawater containing radionuclides derived from a uranium fission reactor.

Claims (14)

  1. 　少なくともアルカリ金属とマンガンとを含む層状マンガン酸化物から構成されており、微小圧縮試験機による測定で１０００ｍＮ以上５０００ｍＮ以下の圧壊強度を有し、無機結合剤および有機成分を含まず、全粒体の９０％以上が粒径０．２ｍｍ以上１．７ｍｍ以下の粒体であり、かさ密度０．９ｇ／ｃｍ３以上である、層状マンガン酸化物成形体。 It is composed of layered manganese oxide containing at least alkali metal and manganese, has a crushing strength of 1000 mN or more and 5000 mN or less as measured by a microcompression tester, does not contain inorganic binders and organic components, and is a whole grain. A layered manganese oxide molded product having a particle size of 0.2 mm or more and 1.7 mm or less and a bulk density of 0.9 g / cm 3 or more in 90% or more.
  2. 　組成式ＡｘＭｎＯ２で表され、Ａはナトリウム及びカリウムから選ばれる１種以上のアルカリ金属を表し、０．２≦ｘ≦０．６である、請求項１に記載の層状マンガン酸化物成形体。 The layered manganese oxide molding according to claim 1, wherein A is represented by the composition formula A x MnO 2 , A represents one or more alkali metals selected from sodium and potassium, and 0.2 ≦ x ≦ 0.6. body.
  3. 　上記層状マンガン酸化物の層間距離が７．０オングストローム以上７．３オングストローム以下である、請求項１または２に記載の層状マンガン酸化物成形体。 The layered manganese oxide molded product according to claim 1 or 2, wherein the interlayer distance between the layered manganese oxides is 7.0 angstroms or more and 7.3 angstroms or less.
  4. 　粉末Ｘ線回折実験において六方晶で帰属した場合の００１ピークのＦＷＨＭが０．４°以上３．５°以下である、請求項１～３のいずれか一項に記載の層状マンガン酸化物成形体。 The layered manganese oxide molded product according to any one of claims 1 to 3, wherein the FWHM of the 001 peak when assigned as a hexagonal crystal in a powder X-ray diffraction experiment is 0.4 ° or more and 3.5 ° or less. ..
  5. 　組成式ＡｘＭｎＯ２で表され、Ａは、少なくともナトリウムとカリウムとを含むアルカリ金属であり、０．４≦ｘ≦０．６であり、
    　粉末Ｘ線回折実験において六方晶で帰属した場合の００１ピークのＦＷＨＭが２．５°以上３．５°以下である、請求項１～４のいずれか一項に記載の層状マンガン酸化物成形体。     Represented by the composition formula A x MnO 2 , A is an alkali metal containing at least sodium and potassium, 0.4 ≦ x ≦ 0.6.
    The layered manganese oxide molded product according to any one of claims 1 to 4, wherein the FWHM of the 001 peak when assigned as a hexagonal crystal in a powder X-ray diffraction experiment is 2.5 ° or more and 3.5 ° or less. ..
  6. 　上記アルカリ金属がカリウムである、請求項１～５のいずれか一項に記載の層状マンガン酸化物成形体。 The layered manganese oxide molded product according to any one of claims 1 to 5, wherein the alkali metal is potassium.
  7. 　撹拌摩耗度が１５重量％以下である、請求項１～６のいずれか一項に記載の層状マンガン酸化物成形体。 The layered manganese oxide molded product according to any one of claims 1 to 6, wherein the degree of agitation wear is 15% by weight or less.
  8. 　上記無機結合剤が、ケイ素、アルミニウム、チタン及びジルコニウム成分から選択される少なくとも１種の無機結合剤である、請求項１～７のいずれか一項に記載の層状マンガン酸化物成形体。 The layered manganese oxide molded product according to any one of claims 1 to 7, wherein the inorganic binder is at least one inorganic binder selected from silicon, aluminum, titanium and zirconium components.
  9. 　炭素濃度が３０００ｐｐｍ以下である、請求項１～８のいずれか一項に記載の層状マンガン酸化物成形体。 The layered manganese oxide molded product according to any one of claims 1 to 8, which has a carbon concentration of 3000 ppm or less.
  10. 　少なくともマンガンを含み、アルカリ土類金属の濃度が１５００ｐｐｍ未満である金属塩水溶液、アルカリ金属水溶液及び酸化剤を、アルカリ金属／マンガンモル比が２以上１０以下、反応液の酸化還元電位が飽和カロメル電極基準で－０．２Ｖ以上０．６Ｖ以下、温度０℃以上１００℃以下、単位容積あたりの攪拌所要動力が０．５ｋＷ／ｍ３以上で混合して混合水溶液を得て、該混合水溶液中でスラリーの固形分濃度が１ｗｔ％以上５ｗｔ％以下で析出させた上で、ろ過した後に析出物質を４０℃以上２００℃以下で熱硬化させる、請求項１～９のいずれか一項に記載の層状マンガン酸化物成形体の製造方法。 A metal salt aqueous solution, an alkali metal aqueous solution and an oxidizing agent containing at least manganese and having an alkaline earth metal concentration of less than 1500 ppm, the alkali metal / manganese molar ratio is 2 or more and 10 or less, and the oxidation-reduction potential of the reaction solution is a saturated caromel electrode. A mixed aqueous solution is obtained by mixing at -0.2 V or more and 0.6 V or less, a temperature of 0 ° C. or more and 100 ° C. or less, and a required stirring power per unit volume of 0.5 kW / m 3 or more, and in the mixed aqueous solution. The layered layer according to any one of claims 1 to 9, wherein the solid content concentration of the slurry is precipitated at 1 wt% or more and 5 wt% or less, and then the precipitated substance is thermally cured at 40 ° C. or higher and 200 ° C. or lower after filtration. A method for producing a manganese oxide molded product.
  11. 　上記アルカリ金属がカリウムである、請求項１０に記載の層状マンガン酸化物成形体の製造方法。 The method for producing a layered manganese oxide molded product according to claim 10, wherein the alkali metal is potassium.
  12. 　上記酸化剤が過酸化水素、酸素、空気、およびペルオキソ二硫酸塩からなる群より選ばれる少なくとも１つである、請求項１０または１１に記載の層状マンガン酸化物成形体の製造方法。 The method for producing a layered manganese oxide molded product according to claim 10 or 11, wherein the oxidizing agent is at least one selected from the group consisting of hydrogen peroxide, oxygen, air, and peroxodisulfate.
  13. 　上記混合水溶液中で析出させる上記析出物質が、層間距離９オングストローム以上１０オングストローム以下のブセライトであって、該析出物質が熱硬化過程で層間距離７．０オングストローム以上７．３オングストローム以下のバーネサイトとなる、請求項１０～１２のいずれか一項に記載の層状マンガン酸化物成形体の製造方法。 The precipitated substance precipitated in the mixed aqueous solution is bucelite having an interlayer distance of 9 angstroms or more and 10 angstroms or less, and the precipitated substance becomes burnesite having an interlayer distance of 7.0 angstroms or more and 7.3 angstroms or less in the heat curing process. The method for producing a layered manganese oxide molded product according to any one of claims 10 to 12.
  14. 　請求項１～９のいずれか一項に記載の層状マンガン酸化物成形体を含有する、ストロンチウム吸着剤。 A strontium adsorbent containing the layered manganese oxide molded product according to any one of claims 1 to 9.
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