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WO2012077610A1 - Alkali metal separation and recovery method and alkali metal separation and recovery apparatus - Google Patents

Alkali metal separation and recovery method and alkali metal separation and recovery apparatus Download PDF

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Publication number
WO2012077610A1
WO2012077610A1 PCT/JP2011/077975 JP2011077975W WO2012077610A1 WO 2012077610 A1 WO2012077610 A1 WO 2012077610A1 JP 2011077975 W JP2011077975 W JP 2011077975W WO 2012077610 A1 WO2012077610 A1 WO 2012077610A1
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Prior art keywords
alkali metal
nanofiltration membrane
water
membrane unit
separation
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PCT/JP2011/077975
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French (fr)
Japanese (ja)
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谷口 雅英
寛生 高畠
佐々木 崇夫
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東レ株式会社
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Priority to CN201180058613.5A priority Critical patent/CN103249471B/en
Publication of WO2012077610A1 publication Critical patent/WO2012077610A1/en

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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B26/00Obtaining alkali, alkaline earth metals or magnesium
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D61/00Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/027Nanofiltration
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D61/00Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/027Nanofiltration
    • B01D61/0271Nanofiltration comprising multiple nanofiltration steps
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/44Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/442Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2317/00Membrane module arrangements within a plant or an apparatus
    • B01D2317/02Elements in series
    • B01D2317/022Reject series
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2317/00Membrane module arrangements within a plant or an apparatus
    • B01D2317/02Elements in series
    • B01D2317/025Permeate series
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/001Processes for the treatment of water whereby the filtration technique is of importance
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/02Treatment of water, waste water, or sewage by heating
    • C02F1/04Treatment of water, waste water, or sewage by heating by distillation or evaporation
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/24Treatment of water, waste water, or sewage by flotation
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/28Treatment of water, waste water, or sewage by sorption
    • C02F1/283Treatment of water, waste water, or sewage by sorption using coal, charred products, or inorganic mixtures containing them
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/42Treatment of water, waste water, or sewage by ion-exchange
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/44Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/441Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/44Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/444Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by ultrafiltration or microfiltration
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/44Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/447Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by membrane distillation
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/68Treatment of water, waste water, or sewage by addition of specified substances, e.g. trace elements, for ameliorating potable water
    • C02F1/683Treatment of water, waste water, or sewage by addition of specified substances, e.g. trace elements, for ameliorating potable water by addition of complex-forming compounds
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/72Treatment of water, waste water, or sewage by oxidation
    • C02F1/722Oxidation by peroxides
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/72Treatment of water, waste water, or sewage by oxidation
    • C02F1/76Treatment of water, waste water, or sewage by oxidation with halogens or compounds of halogens
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00Nature of the contaminant
    • C02F2101/10Inorganic compounds
    • C02F2101/20Heavy metals or heavy metal compounds
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2301/00General aspects of water treatment
    • C02F2301/08Multistage treatments, e.g. repetition of the same process step under different conditions
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00Specific treatment goals
    • C02F2303/04Disinfection
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00Biological treatment of water, waste water, or sewage
    • C02F3/02Aerobic processes
    • C02F3/12Activated sludge processes
    • C02F3/1236Particular type of activated sludge installations
    • C02F3/1268Membrane bioreactor systems
    • C02F3/1273Submerged membrane bioreactors
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02WCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00Technologies for wastewater treatment
    • Y02W10/10Biological treatment of water, waste water, or sewage
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02WCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00Technologies for wastewater treatment
    • Y02W10/30Wastewater or sewage treatment systems using renewable energies
    • Y02W10/37Wastewater or sewage treatment systems using renewable energies using solar energy

Definitions

  • the present invention relates to a method and apparatus for recovering alkali metals such as lithium and potassium from lake water, groundwater, industrial wastewater, and the like. More specifically, the present invention efficiently recovers alkali metals using a multi-stage nanofiltration membrane. It is related with the method and apparatus for doing.
  • lithium carbonate is used for a surface acoustic wave filter in addition to an electrode material of a lithium ion battery and a heat-resistant glass additive.
  • High purity products are used as filters and transmitters for mobile phones and car navigation systems.
  • Lithium bromide is used as a refrigerant absorbent for large-scale air-conditioning absorption refrigerators in buildings and factories, and lithium hydroxide is used as a raw material for grease and lithium batteries (primary and secondary) for automobiles.
  • Applications of metallic lithium include foil as a negative electrode material for primary batteries and raw materials for butyl lithium for synthetic rubber catalysts.
  • salt lake brine and ore are contained in salt lake brine and ore, and it is advantageous to recover resources from salt lake brine in terms of production cost.
  • the composition is largely classified into chloride brine, sulfate brine, carbonate brine, and calcium brine.
  • sulfate brine which has the largest amount of resources, has a low solubility of sulfate during the purification process. Many of them form salts or contain a lot of alkaline earth metal salts or sulfates, and it is difficult to efficiently recover lithium.
  • Patent Document 1-2 a method using an adsorbent
  • the cost is difficult, and it has been established as a technique for stably recovering lithium at a low cost.
  • Conventional low-cost methods include drying the brine in the sun and removing impurities while concentrating, but when the lithium concentration is low or the alkaline earth metal salt or sulfate concentration is high, etc. There was a problem that it was difficult to apply.
  • electrodialysis and membrane filtration are being studied (Non-Patent Document 1), but they have not been put into practical use.
  • An object of the present invention is to provide a method and an apparatus for efficiently recovering alkali metals such as lithium and potassium from lake water, groundwater, industrial wastewater and the like.
  • the present invention relates to the following embodiments (1) to (15).
  • an alkali metal separation / recovery method wherein the nanofiltration membrane unit is configured in at least two stages, and the concentrated water of the preceding nanofiltration membrane unit is used as supply water for the latter nanofiltration membrane unit.
  • the ratio of the sulfate ion permeability to the alkali metal permeability in the first-stage nanofiltration membrane unit is smaller than the ratio of the sulfate ion permeability to the alkali metal permeability in the final-stage nanofiltration membrane unit.
  • the nanofiltration membrane in the first-stage nanofiltration membrane unit contains an aliphatic polyamide as a main component, and the nanofiltration membrane in the final-stage nanofiltration membrane unit has an aromatic polyamide as a main component.
  • the method further comprises a permeate concentration step of concentrating the permeate of at least one nanofiltration membrane unit, and after that step, the alkali metal is recovered by post-treatment.
  • At least the permeated water of the nanofiltration membrane unit at the final stage is subjected to a permeated water concentration step, and then the alkali metal is recovered by post-treatment after removing the purification inhibitor (7) or ( The alkali metal separation and recovery method according to 8).
  • An alkali metal separation and recovery device for separating permeated water containing alkali metal from raw water containing alkali metal using a nanofiltration membrane and recovering the alkali metal contained in the permeated water by post-treatment.
  • the apparatus includes at least two nanofiltration membrane units, and the concentrated water line of the preceding nanofiltration membrane unit is connected to the supply water line of the subsequent nanofiltration membrane unit. Recovery device.
  • the present invention makes it possible to efficiently recover alkali metals such as lithium and potassium from water in which various solutes coexist.
  • FIG. 1 is a schematic flowchart showing one embodiment of the alkali metal separation and recovery method according to the present invention (the above embodiments (1) to (5)).
  • FIG. 2 is a schematic flow diagram showing one embodiment of pressurizing the second-stage feed water of the nanofiltration membrane unit according to the present invention (the above embodiment (6)).
  • FIG. 3 is a schematic flowchart showing one embodiment of a method for separating and recovering alkali metal after concentrating the permeated water of the nanofiltration membrane according to the present invention (the above embodiments (7) and (8)). ).
  • FIG. 4 is a schematic flow diagram showing an embodiment of a method for separating and recovering alkali metal after removing the purification inhibitor after concentrating the final permeate of the nanofiltration membrane unit according to the present invention.
  • FIG. 5 is a schematic flow diagram showing one embodiment of adding an acid to the feed water of the nanofiltration membrane according to the present invention (the above embodiment (10)).
  • FIG. 6 is a schematic flow diagram showing an embodiment in which the purification inhibitor is removed from the final concentrated water of the nanofiltration membrane according to the present invention and then refluxed to the raw water containing the alkali metal (the above embodiment ( 11)).
  • FIG. 7 is a schematic flow diagram showing one embodiment of mixing diluted water with the feed water of the nanofiltration membrane according to the present invention (the above embodiment (12)).
  • FIG. 8 is a schematic flow diagram showing an embodiment in which the permeated water produced by concentrating the permeated water of the nanofiltration membrane according to the present invention is used for dilution of the nanofiltration membrane feed water (the above embodiment ( 13)).
  • FIG. 9 is a schematic flow diagram showing one embodiment of heating the feed water of the nanofiltration membrane according to the present invention (the above embodiment (14)).
  • the number of nanofiltration membrane units can be three or more, and the scope of the present invention is not limited to these embodiments.
  • FIG. 1 An example of the execution flow of the alkali metal recovery of the present invention is shown in FIG.
  • raw water 1 containing alkali metal is temporarily stored in a raw water tank 2 and then processed by a pretreatment unit 3 by a raw water supply pump 4.
  • the concentrated water of the first-stage nanofiltration membrane unit 6 is sent to the second-stage nanofiltration membrane unit 7, the alkali metal is permeated and separated as in the first stage, and the final concentrated water 8 is discharged out of the system.
  • the nanofiltration membrane permeated water is sent to the recovery unit 9, and the alkali metal is recovered (the above embodiment (1)).
  • the alkali metal that is the subject of the present invention is preferably one containing at least lithium, and in salt lake brine etc. for carrying out the method of the present invention, among alkali metals such as sodium, potassium, rubidium, cesium and the like in addition to lithium.
  • At least one metal, alkaline earth metal such as magnesium, calcium, strontium, typical elements (aluminum, tin, lead, etc.), transition elements (iron, copper, cobalt, manganese, etc.), and one or more conjugates
  • a compound composed of a salt with a base for example, chloride ion, nitrate ion, sulfate ion, carbonate ion, acetate ion, etc.
  • a base for example, chloride ion, nitrate ion, sulfate ion, carbonate ion, acetate ion, etc.
  • the concentration of each of these components is not particularly limited, but the lithium ion concentration is preferably in the range of 0.5 ppm or more and 10,000 ppm or less, more preferably in the range of 5 ppm or more and 5000 ppm or less, and more preferably, from the viewpoint of the efficiency of separation and recovery.
  • the magnesium ion concentration in the alkali metal salt aqueous solution serving as raw water is preferably 1000 times or less as compared with the lithium ion concentration. More preferably, it is efficient when it is 500 times or less, and more preferably 100 times or less.
  • the magnesium ion concentration in the aqueous solution containing the alkali metal salt is 7 times or less than the lithium ion concentration in the aqueous solution. It is preferable to perform a removal treatment using a separation membrane. If this ratio exceeds 7 times, the recovery efficiency of the purified alkali metal salt is significantly reduced.
  • the weight of the purification inhibiting substance at this time is calculated based on the weight in terms of ions such as magnesium ions and sulfate ions.
  • the weight in terms of lithium ion and the weight of the purification inhibitor can be determined by quantifying various ion concentrations in an aqueous solution containing an alkali metal salt, for example, by ion chromatography.
  • the content of the purification inhibitor in the raw water is different depending on the composition and concentration of the purification inhibitor depending on the properties of the raw water.
  • salt lake brine contains magnesium ions and sulfate ions in the range of 100 ppm to 30,000 ppm.
  • the nanofiltration membrane referred to here is a membrane defined by IUPAC as “a pressure-driven membrane in which particles and polymers of a size smaller than 2 nm are blocked”, but is effective for application to the present invention.
  • the membrane has a charge on the membrane surface, and has improved ion separation efficiency by a combination of separation by pores (size separation) and electrostatic separation by charge on the membrane surface. It is preferable to apply a nanofiltration membrane that is capable of removing polymers by size separation while separating metal ions and other ions having different charge characteristics by charging.
  • the glucose removal rate is particularly good when permeating a 1000 ppm isopropyl alcohol aqueous solution of 25 ° C. and pH 6.5 and a 1000 ppm glucose aqueous solution of 25 ° C. and pH 6.5 at an operating pressure of 0.5 MPa.
  • a nanofiltration membrane that is 90% or more and the difference between the glucose removal rate and the isopropyl alcohol removal rate is 30% or more, alkali metal salts, especially lithium salts and purification inhibitors, are not affected by the total salt concentration. Separation is particularly preferred because it is achieved with very high efficiency.
  • the purified alkali metal salt can be separated and recovered by a crystallization operation induced by concentration of an aqueous solution, heating, cooling, or addition of a nucleating agent. It is preferred that the sulfate is removed. Therefore, the removal rate of magnesium sulfate is 90% or more when passing through a 2000 ppm magnesium sulfate aqueous solution at 25 ° C. and pH 6.5 and a 2000 ppm lithium chloride aqueous solution at 25 ° C. and pH 6.5 at an operating pressure of 0.5 MPa, preferably 95%.
  • % Or more more preferably 97% or more, and using a nanofiltration membrane having a lithium chloride removal rate of 70% or less, preferably 50% or less, more preferably 30% or less, depending on the total salt concentration. Separation of lithium salt and purification inhibitor is achieved with extremely high efficiency. Further, it is preferable to recover the purified alkali metal salt by concentration of the alkali metal salt after the step of the separation membrane of the present invention.
  • the temperature dependency of the solubility is used, or recovery is performed by a known method of recovering potassium chloride by adding a poor solvent such as ethanol.
  • a lithium salt it is recovered as lithium carbonate, for example, by adding a carbonate to an aqueous solution, taking advantage of its low solubility compared to other alkali metal salts. This is because sodium carbonate and potassium carbonate have a sufficiently high solubility in water (20 g or more per 100 mL of water), whereas the solubility of lithium carbonate is only 1.33 g per 100 mL of water at 25 ° C, and the solubility is higher at higher temperatures. It uses the decline.
  • the nanofiltration membrane unit is composed of a modularized nanofiltration membrane, for example, one or a plurality of spiral nanofiltration membrane elements connected in a container and connected in series or in parallel. Refers to things.
  • the low-concentration water 11 after the alkali metal is recovered by the recovery unit 9 can be drained or returned to the raw water depending on the alkali metal content. Moreover, since the final concentrated water 8 of the nanofiltration membrane has pressure energy, it is preferable to apply an energy recovery unit because it saves energy.
  • the pretreatment unit 3 is not particularly limited, and can be appropriately selected depending on the raw aqueous state, such as removal of turbid components and sterilization.
  • Chlorine is preferably used as the disinfectant, and for example, chlorine gas or sodium hypochlorite may be added to the feed water as free chlorine so as to be in the range of 1 to 5 mg / l.
  • certain fungicides may not have chemical durability. In that case, add as much upstream as possible to the feed water, and further, near the feed water inlet side of the semipermeable membrane unit. It is preferable to disable the disinfectant. For example, in the case of free chlorine, its concentration is measured, and the addition amount of chlorine gas and sodium hypochlorite is controlled based on this measured value, or a reducing agent such as sodium bisulfite is added.
  • a flocculant such as polyaluminum chloride, sulfate band, iron (III) chloride.
  • the agglomerated supply water is then subjected to sand filtration after settling on an inclined plate or the like, or by filtration through a microfiltration membrane or an ultrafiltration membrane in which a plurality of hollow fiber membranes are bundled.
  • Supply water suitable for passing through the latter semipermeable membrane unit can be obtained.
  • sand filtration when sand filtration is used for pretreatment, it is possible to apply gravity-type filtration that naturally flows down, or it is possible to apply pressure-type filtration in which a pressure tank is filled with sand. .
  • sand to be filled single-component sand can be applied.
  • anthracite, silica sand, garnet, pumice, and the like can be combined to increase filtration efficiency.
  • the microfiltration membrane and the ultrafiltration membrane are not particularly limited, and a flat membrane, a hollow fiber membrane, a tubular membrane, a pleated shape, or any other shape can be used as appropriate.
  • the material of the membrane is not particularly limited, and it is possible to use an inorganic material such as polyacrylonitrile, polyphenylene sulfone, polyphenylene sulfide sulfone, polyvinylidene fluoride, polypropylene, polyethylene, polysulfone, polyvinyl alcohol, cellulose acetate, or ceramic. it can. Moreover, even if it is a filtration system, any of the pressure filtration system which pressurizes and filters supply water, and the suction filtration system which sucks and filters the permeation
  • agglomerated membrane filtration or membrane-based activated sludge method in which a microfiltration membrane or an ultrafiltration membrane is immersed in a coagulation sedimentation tank or a biological treatment tank for filtration, may be applied.
  • MLR membrane-based activated sludge method
  • the organic matter when the supply water contains a lot of soluble organic matter, the organic matter can be decomposed by adding chlorine gas or sodium hypochlorite. Removal is possible.
  • a chelating agent such as an organic polymer electrolyte or sodium hexametaphosphate may be added, or exchanged with soluble ions using an ion exchange resin or the like.
  • iron or manganese when iron or manganese is present in a soluble state, it is preferable to use an aeration oxidation filtration method or a contact oxidation filtration method.
  • the nanofiltration membrane unit is different from the first stage to the last stage (the above embodiment (2)).
  • the molecular weight and charge characteristics of the nanofiltration membrane are optimized according to the water supply quality gradually changing at each stage of the nanofiltration membrane. Therefore, it is possible to increase the separation efficiency.
  • the permeation amount decreases due to the pressure loss due to flow resistance and the decrease in effective filtration pressure due to the increase in feed water concentration from the previous stage to the latter stage, the pure water permeability performance of the latter nanofiltration membrane is larger than the previous stage. Is preferable (the above embodiment (3)).
  • the pure water feeding performance here can be measured by allowing pure water applied with pressure (usually 0.3 to 0.5 MPa) to pass through the nanofiltration membrane, and is measured at a standard temperature (usually 25 ° C.). It is a value obtained by measuring the membrane area and the amount of water permeated per unit time.
  • the concentration of the feed water increases as the latter stage, but not a small amount of alkali metal ions permeate the nanofiltration membrane, so that the latter feed water contains other solutes (alkaline earth metals and sulfate ions) with respect to the alkali metal concentration.
  • the ratio of such multivalent ions) is increased, and the alkali metal content of the permeated water is also decreased from the previous stage. Therefore, it is preferable to use a nanofiltration membrane with higher separation performance as the latter stage.
  • the ratio of the sulfate ion permeability to the alkali metal permeability the ratio of the first-stage nanofiltration membrane unit is smaller than the ratio of the final-stage nanofiltration membrane unit, thereby making the present invention more efficient.
  • Such a nanofiltration membrane can be realized by increasing the pore diameter (fractionated molecular weight) while increasing the surface charge of the latter nanofiltration membrane as compared with the previous stage.
  • a method for increasing the surface charge for example, as shown in the literature (Photoinduced grafting of ultrafiltration membranes: comparison of poly (ether sulfone) and poly (sulfone), B. Kaeselev et al., Journal of Membrane Science) Examples thereof include a method in which radicals (active sites) are produced by UV, electron beam, plasma, etc., and graft polymerization is performed, and a method in which a polymer chain is cleaved with an oxidizing agent or the like.
  • a polycondensation reaction between a polyfunctional amine and a polyfunctional acid halide is performed from the viewpoint of achieving both high water permeability and separation performance and high potential for comprehensive membrane performance.
  • a composite semipermeable membrane having an ultrathin film layer of the obtained crosslinked polyamide on a microporous support membrane is preferred.
  • the nanofiltration membrane in the preceding nanofiltration membrane unit that requires high separation efficiency is mainly composed of aliphatic polyamide (that is, the number of amide bonds of aliphatic polyamide is larger than that of aromatic polyamide).
  • the nanofiltration membrane in the latter nanofiltration membrane unit that requires high permeation performance preferably contains aromatic polyamide as a main component (the above embodiment (5)).
  • piperazine-based amines and derivatives thereof represented by the formula [I] are preferable, and piperazine, 2,5-dimethylpiperazine, 2-methylpiperazine, 2,6-dimethylpiperazine, 2,3,5- Examples include trimethylpiperazine, 2,5-diethylpiperazine, 2,3,5-triethylpiperazine, 2-n-propylpiperazine, 2,5-di-n-butylpiperazine and the like. Among them, it is particularly preferable to use piperazine or 2,5-dimethylpiperazine, which can obtain a nanofiltration membrane having higher solute removal performance and water permeation performance with a wide composition ratio.
  • R1 to R8 are selected from H, OH, COOH, SO 3 H, NH 2 or C1 to C4 linear or cyclic saturated or unsaturated aliphatic groups.
  • the polyfunctional amine is an amine having two or more amino groups in one molecule, and includes an o-aromatic diamine having two amino groups in the ortho position (o-). Those are preferred. Further, the polyfunctional amines include m-aromatic diamines having two amino groups at the meta position (m-), p-aromatic diamines having two amino groups at the para position (p-), and aliphatic systems. At least one selected from the group consisting of amines and derivatives thereof, and in particular, having a dense and rigid structure, can provide a membrane having excellent blocking performance and water permeability performance, and further excellent durability and particularly heat resistance. It is also preferable that an easy m-aromatic diamine or p-aromatic diamine is contained.
  • o-phenylenediamine is preferably used as the o-aromatic diamine.
  • m-aromatic diamine m-phenylenediamine is preferable, but 3,5-diaminobenzoic acid, 2,6-diaminopyridine and the like can also be used.
  • p-aromatic diamine p-phenylenediamine is preferable, but 2,5-diaminobenzenesulfonic acid, p-xylylenediamine and the like can also be used.
  • the molar ratio of these polyfunctional amines in the film-forming stock solution can be appropriately selected depending on the amine and acid halide used. However, the higher the addition ratio of o-aromatic diamine, the better the water permeability. On the other hand, the blocking performance of the entire solute is reduced. Moreover, the separation performance of multivalent ions and monovalent ions is improved by increasing the number of aliphatic polyfunctional amines. This makes it possible to obtain the liquid separation membrane of the present invention that satisfies the desired water permeation performance, ion separation performance, and blocking performance of the entire solute.
  • the heat stability is lowered. Therefore, when heat resistance is important, the heat resistance can be improved by reducing the number of aliphatic amines.
  • polyfunctional acid halides are acid halides or polyfunctional acid anhydride halides having two or more carbonyl halide groups in one molecule, and the function of separating crosslinked polyamide by reaction with the above polyfunctional amine.
  • there is no particular limitation as long as it forms a layer For example, 1,3,5-cyclohexanetricarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,3 -A mixture of benzenedicarboxylic acid and acid halide of 1,4-benzenedicarboxylic acid.
  • dicarboxylic acids and tricarboxylic acids represented by the formulas [II] and [III] are preferable, particularly good for economics, because the film-forming property is good, the entire solute blocking performance is uniform, and there are few defects and variations.
  • trimesic acid chloride which is an acid halide of 1,3,5-benzenetricarboxylic acid, is preferable.
  • R is selected from H or a C1-C3 hydrocarbon.
  • R is selected from H or a C1-C3 hydrocarbon.
  • the polyfunctional acid anhydride halide is a carbonyl halide of benzoic anhydride or phthalic anhydride having one or more acid anhydride moieties and one or more halogenated carbonyl groups in one molecule.
  • Trimellitic anhydride halides and derivatives thereof represented by the following general formula [IV] are preferably used.
  • X1 and X2 are any of C1 to C3 linear or cyclic saturated, unsaturated aliphatic group, H, OH, COOH, SO 3 H, COF, COCl, COBr, COI. To be elected. Alternatively, an acid anhydride may be formed between X1 and X2.
  • X3 is selected from any of C1 to C3 linear or cyclic saturated or unsaturated aliphatic groups, H, OH, COOH, SO 3 H, COF, COCl, COBr, and COI.
  • Y is selected from H, F, Cl, Br, I or C1-C3 hydrocarbons.
  • the permeate concentration usually does not become higher than that of the raw water, so that the alkali metal can be efficiently recovered in the post-treatment. It is also a preferred embodiment to add a step of concentrating the permeated water of the nanofiltration membrane (permeated water concentrating step) (the above embodiment (7)).
  • the permeated water concentration step can include various methods such as distillation, membrane separation, adsorption / desorption, and ion exchange, but the alkali metal is non-volatile and has a very small size.
  • the reverse osmosis membrane having high blocking performance refers to a reverse osmosis membrane having an alkali metal removal rate of 95% or more.
  • FIG. 3 illustrates a case where a reverse osmosis membrane is used as the concentration unit 14.
  • components such as alkaline earth metals are concentrated, and as a result, the concentration of the alkaline earth metal contained in the permeated water becomes higher.
  • a method of removing the alkaline earth metal by the earth metal removal unit 17 and then recovering the alkali metal in the post-treatment 9 is also a preferred embodiment (the above embodiment (9)).
  • permeated water 15 is obtained as fresh water, which can be discharged out of the system, or can be reused as process water and the like.
  • the alkaline earth metal concentration in the concentrated water gradually increases, and depending on the operating conditions, it becomes a scale and precipitates on the surface of the nanofiltration membrane. If such a danger is expected, the pH is lowered by adding acid to the raw water or the concentrated water in the previous stage to prevent scale precipitation. It is preferable (the above embodiment (10)). Of course, it is possible to add a scale inhibitor. However, since there are risks such as environmental impact and possible leakage of the scale inhibitor, caution is required in the addition.
  • FIG. 5 shows an embodiment in which the acid 19 is added to the feed water in the latter stage (concentrated water in the former stage).
  • the concentrated water 8 of the nanofiltration membrane contains an alkaline earth metal or the like at a high concentration, but generally contains alkali metal ions at a concentration higher than the raw water concentration although the ratio is smaller than other components. 6, after the alkaline earth metal is removed by the alkali metal removal unit 17, the recovery rate of the alkali metal in the raw water can be increased by refluxing the raw water (the above embodiment (11)).
  • the dilution water 20 may be water having a lower concentration than the raw water, such as natural water such as river water, ground water, rainwater, or tap water, but the concentration units 14 and 14 'as shown in FIGS.
  • the permeated water 15 it is very preferable because the water can be efficiently recovered and reused (the embodiment (13); see FIG. 8).
  • the raw water and the nanofiltration membrane supply water are heated in advance. It is preferable as a means for improving efficiency. (Embodiment (14) above).
  • the heat source is not particularly limited, but it is efficient to heat the system to which the present invention is applied using waste heat such as an evaporation method or a membrane distillation method, or heat generated by a pressure pump.
  • the present invention relates to an apparatus for recovering alkali metals such as lithium and potassium from lake water, groundwater, industrial wastewater, and the like, and more particularly to an alkali metal efficiently using a multi-stage nanofiltration membrane.
  • alkali metals such as lithium and potassium
  • the present invention relates to an apparatus for recovering alkali metals such as lithium and potassium from lake water, groundwater, industrial wastewater, and the like, and more particularly to an alkali metal efficiently using a multi-stage nanofiltration membrane.

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Abstract

The invention relates to an alkali metal separation and recovery method that comprises separation of an alkali metal-containing permeate from raw water containing alkali metals using a nanofiltration membrane and recovery of the alkali metal contained in the permeate using an after-treatment. The method is characterized in that the nanofiltration membrane unit is configured in at least two stages and the concentrated water from the preceding nanofiltration membrane unit is used as the water supplied to the latter nanofiltration membrane unit.

Description

アルカリ金属分離回収方法およびアルカリ金属分離回収装置Alkali metal separation and recovery method and alkali metal separation and recovery apparatus
 本発明は、湖水、地下水、産業廃水などからリチウムやカリウムなどのアルカリ金属を回収する方法および装置に関するものであり、さらに詳しくは、複数段のナノ濾過膜を用いて効率的にアルカリ金属を回収するための方法および装置に関するものである。 The present invention relates to a method and apparatus for recovering alkali metals such as lithium and potassium from lake water, groundwater, industrial wastewater, and the like. More specifically, the present invention efficiently recovers alkali metals using a multi-stage nanofiltration membrane. It is related with the method and apparatus for doing.
 近年、世界の経済発展に伴い、鉱物資源の需要拡大が著しい。しかし、半導体産業をはじめとして広く工業的に不可欠な鉱物資源のうち、地殻中の埋蔵量が多いものであっても、採掘や精錬のコストが高く経済的に採算が取れない資源や、特定地域に資源が局在化しており、これまで採掘が見合わせられてきたものも少なくなかった。一方で、環境問題も大きくクローズアップされてきており、循環型社会構築が望まれている。特に、二酸化炭素排出削減で注目を浴びている点から、電気自動車、それに使用されるモーターやバッテリー開発が加速されている。特に、バッテリーに関しては、リチウムイオン二次電池が、そのエネルギー密度、軽量さから電気自動車の主力バッテリーとして期待されている。リチウム化合物の用途として、例えば炭酸リチウムはリチウムイオン電池の電極材や耐熱ガラス添加剤のほか、弾性表面波フィルター向けにも用いられる。特に高純度のものは、携帯電話、カーナビ等フィルター及び発信器として使用されている。臭化リチウムの用途はビル、工場などの大型空調用吸収式冷凍機の冷媒吸収材として、水酸化リチウムの用途は自動車等のグリース及びリチウム電池(一次、二次)向けの原料である。金属リチウムの用途は一次電池の負極材としての箔及び合成ゴム触媒用のブチルリチウム向け原料などである。 In recent years, with the global economic development, the demand for mineral resources has increased significantly. However, among the mineral resources that are widely industrially indispensable including the semiconductor industry, even if the reserves in the crust are large, resources that are not economically profitable due to high mining and refining costs, and certain areas However, many resources have been postponed until now. On the other hand, environmental problems have been greatly highlighted, and the construction of a recycling society is desired. In particular, the development of electric vehicles, motors used in them, and batteries are accelerating because they are attracting attention for reducing carbon dioxide emissions. In particular, regarding batteries, lithium ion secondary batteries are expected as the main battery of electric vehicles because of their energy density and light weight. As an application of the lithium compound, for example, lithium carbonate is used for a surface acoustic wave filter in addition to an electrode material of a lithium ion battery and a heat-resistant glass additive. High purity products are used as filters and transmitters for mobile phones and car navigation systems. Lithium bromide is used as a refrigerant absorbent for large-scale air-conditioning absorption refrigerators in buildings and factories, and lithium hydroxide is used as a raw material for grease and lithium batteries (primary and secondary) for automobiles. Applications of metallic lithium include foil as a negative electrode material for primary batteries and raw materials for butyl lithium for synthetic rubber catalysts.
 リチウムは、塩湖かん水、および鉱石中に含まれており、生産コスト面で塩湖かん水からの資源回収が有利である。これらは、主にチリ,ボリビア、アルゼンチンに存在し、埋蔵量も多い。組成としては、大きく、塩化物かん水,硫酸塩かん水,炭酸塩かん水,カルシウムかん水に分類されるが、このなかで、もっとも資源量が多い硫酸塩かん水は、精製の過程で硫酸塩が難溶性の塩を形成したり、アルカリ土類金属塩や硫酸塩を多く含有したりするものが多く、効率的にリチウム回収することが困難であった。 リ チ ウ ム Lithium is contained in salt lake brine and ore, and it is advantageous to recover resources from salt lake brine in terms of production cost. These exist mainly in Chile, Bolivia, and Argentina, and have large reserves. The composition is largely classified into chloride brine, sulfate brine, carbonate brine, and calcium brine. Among these, sulfate brine, which has the largest amount of resources, has a low solubility of sulfate during the purification process. Many of them form salts or contain a lot of alkaline earth metal salts or sulfates, and it is difficult to efficiently recover lithium.
 これを解決する方策として、吸着剤による方法(特許文献1-2)などが提案されているが、コストが高いことが難点であり、低コストで安定的にリチウムを回収する技術として確立されていない。従来の低コスト方法としては、かん水を天日乾燥して、濃縮しつつ不純物を取り除く方法が挙げられるが、リチウム濃度が低い場合やアルカリ土類金属塩や硫酸塩の濃度が高い場合などには適用困難という問題があった。さらに、電気透析法や膜濾過法も検討されつつある(非特許文献1)が、実用化に至っていない。 In order to solve this problem, a method using an adsorbent (Patent Document 1-2) has been proposed. However, the cost is difficult, and it has been established as a technique for stably recovering lithium at a low cost. Absent. Conventional low-cost methods include drying the brine in the sun and removing impurities while concentrating, but when the lithium concentration is low or the alkaline earth metal salt or sulfate concentration is high, etc. There was a problem that it was difficult to apply. Furthermore, electrodialysis and membrane filtration are being studied (Non-Patent Document 1), but they have not been put into practical use.
 一方、同じアルカリ金属であるカリウムは,肥料をはじめ,食品,飼料,工業薬品,医薬品などに多用されている。現在、リチウムのような深刻な資源問題にはなっていないものの、発展途上国の爆発的な人口増加・経済成長に伴う資源の枯渇が懸念されている。 On the other hand, potassium, which is the same alkali metal, is frequently used for fertilizers, foods, feeds, industrial chemicals, pharmaceuticals and the like. Although it is not currently a serious resource problem like lithium, there is concern about the depletion of resources due to explosive population growth and economic growth in developing countries.
日本国特開2009-161794号公報Japanese Unexamined Patent Publication No. 2009-161794 日本国特開平4-293541号公報Japanese Laid-Open Patent Publication No.4-293541
 本発明の目的は、湖水、地下水、産業廃水などからリチウムやカリウムなどのアルカリ金属を効率的に回収する方法および装置を提供することにある。 An object of the present invention is to provide a method and an apparatus for efficiently recovering alkali metals such as lithium and potassium from lake water, groundwater, industrial wastewater and the like.
 前記課題を解決するために、本発明は以下の(1)~(15)の実施態様に関する。 In order to solve the above problems, the present invention relates to the following embodiments (1) to (15).
 (1)ナノ濾過膜を用いてアルカリ金属を含有する原水からアルカリ金属を含む透過水を分離すること、及び前記透過水に含まれるアルカリ金属を後処理で回収すること、を含むアルカリ金属分離回収方法において、ナノ濾過膜ユニットを少なくとも2段に構成し、後段のナノ濾過膜ユニットの供給水として前段のナノ濾過膜ユニットの濃縮水を用いることを特徴とするアルカリ金属分離回収方法。 (1) Separating and recovering alkali metal containing alkali metal from raw water containing alkali metal using a nanofiltration membrane, and recovering alkali metal contained in the permeated water by post-treatment In the method, an alkali metal separation / recovery method, wherein the nanofiltration membrane unit is configured in at least two stages, and the concentrated water of the preceding nanofiltration membrane unit is used as supply water for the latter nanofiltration membrane unit.
 (2)前記ナノ濾過膜ユニットにおいて、第1段のナノ濾過膜ユニットと最終段のナノ濾過膜ユニットが異なることを特徴とする(1)に記載のアルカリ金属分離回収方法。 (2) The alkali metal separation and recovery method according to (1), wherein the first nanofiltration membrane unit and the last nanofiltration membrane unit are different in the nanofiltration membrane unit.
 (3)前記第1段のナノ濾過膜ユニットの純水透水性能が前記最終段のナノ濾過膜ユニットの純水透水性能よりも小さいことを特徴とする(2)に記載のアルカリ金属分離回収方法。 (3) The method for separating and recovering alkali metal according to (2), wherein the pure water permeability of the first nanofiltration membrane unit is smaller than the pure water permeability of the final nanofiltration membrane unit. .
 (4)前記第1段のナノ濾過膜ユニットにおけるアルカリ金属透過率に対する硫酸イオン透過率の比が、前記最終段のナノ濾過膜ユニットにおけるアルカリ金属透過率に対する硫酸イオン透過率の比よりも小さいことを特徴とする(2)または(3)に記載のアルカリ金属分離回収方法。 (4) The ratio of the sulfate ion permeability to the alkali metal permeability in the first-stage nanofiltration membrane unit is smaller than the ratio of the sulfate ion permeability to the alkali metal permeability in the final-stage nanofiltration membrane unit. (2) or the alkali metal separation and recovery method according to (3).
 (5)前記第1段のナノ濾過膜ユニット内のナノ濾過膜が脂肪族系ポリアミドを主成分として含み、前記最終段のナノ濾過膜ユニット内のナノ濾過膜が芳香族系ポリアミドを主成分として含むことを特徴とする(2)~(4)のいずれか一項に記載のアルカリ金属分離回収方法。 (5) The nanofiltration membrane in the first-stage nanofiltration membrane unit contains an aliphatic polyamide as a main component, and the nanofiltration membrane in the final-stage nanofiltration membrane unit has an aromatic polyamide as a main component. The method for separating and recovering alkali metal according to any one of (2) to (4), wherein
 (6)少なくとも2段に構成されたナノ濾過膜ユニットがすべて同じナノ濾過膜ユニットであるとともに、少なくとも1つのナノ濾過膜ユニットの濃縮水を昇圧することを特徴とする(1)に記載のアルカリ金属分離回収方法。 (6) The alkali according to (1), wherein the nanofiltration membrane units configured in at least two stages are all the same nanofiltration membrane unit, and the pressure of the concentrated water of at least one nanofiltration membrane unit is increased. Metal separation and recovery method.
 (7)少なくとも1つのナノ濾過膜ユニットの透過水を濃縮する透過水濃縮工程をさらに含み、その工程後、アルカリ金属を後処理で回収することを特徴とする(1)~(6)のいずれか一項に記載のアルカリ金属分離回収方法。 (7) The method further comprises a permeate concentration step of concentrating the permeate of at least one nanofiltration membrane unit, and after that step, the alkali metal is recovered by post-treatment. The alkali metal separation and recovery method according to claim 1.
 (8)前記透過水濃縮工程が蒸発法、膜蒸留法、アルカリ金属除去率95%以上の逆浸透膜を用いる方法のいずれかであることを特徴とする(7)に記載のアルカリ金属分離回収方法。 (8) The alkali metal separation and recovery described in (7), wherein the permeate concentration step is any one of an evaporation method, a membrane distillation method, and a method using a reverse osmosis membrane having an alkali metal removal rate of 95% or more. Method.
 (9)少なくとも最終段のナノ濾過膜ユニットの透過水を透過水濃縮工程に供した後、精製阻害物質を除去してから後処理でアルカリ金属を回収することを特徴とする(7)または(8)に記載のアルカリ金属分離回収方法。 (9) At least the permeated water of the nanofiltration membrane unit at the final stage is subjected to a permeated water concentration step, and then the alkali metal is recovered by post-treatment after removing the purification inhibitor (7) or ( The alkali metal separation and recovery method according to 8).
 (10)少なくとも1つのナノ濾過膜ユニットの供給水に酸を添加することを特徴とする(1)~(9)のいずれか一項に記載のアルカリ金属分離回収方法。 (10) The alkali metal separation and recovery method according to any one of (1) to (9), wherein an acid is added to the water supplied to at least one nanofiltration membrane unit.
 (11)最終段のナノ濾過膜ユニットの濃縮水に含有される精製阻害物質を除去処理し、その処理水をいずれかのナノ濾過膜ユニットの供給水ラインに還流することを特徴とする(1)~(10)のいずれか一項に記載のアルカリ金属分離回収方法。 (11) The purification inhibitor contained in the concentrated water of the final nanofiltration membrane unit is removed, and the treated water is returned to the supply water line of any of the nanofiltration membrane units (1) ) To (10) The alkali metal separation and recovery method according to any one of the above.
 (12)少なくとも1つのナノ濾過膜ユニットの供給水に希釈水を混合することを特徴とする(1)~(11)のいずれか一項に記載のアルカリ金属分離回収方法。 (12) The alkali metal separation and recovery method according to any one of (1) to (11), wherein dilution water is mixed with water supplied to at least one nanofiltration membrane unit.
 (13)前記希釈水が、前記透過水濃縮工程において産生される淡水であることを特徴とする(12)に記載のアルカリ金属分離回収方法。 (13) The alkali metal separation and recovery method according to (12), wherein the dilution water is fresh water produced in the permeate concentration step.
 (14)少なくとも1つのナノ濾過膜ユニットの供給水を加温することを特徴とする(1)~(13)のいずれか一項に記載のアルカリ金属分離回収方法。 (14) The alkali metal separation and recovery method according to any one of (1) to (13), wherein the water supplied to at least one nanofiltration membrane unit is heated.
 (15)ナノ濾過膜を用いてアルカリ金属を含有する原水からアルカリ金属を含む透過水を分離し、前記透過水に含まれる前記アルカリ金属を後処理で回収するためのアルカリ金属分離回収装置であって、該装置が少なくとも2段のナノ濾過膜ユニットを含み、前段のナノ濾過膜ユニットの濃縮水ラインが後段のナノ濾過膜ユニットの供給水ラインに連結されていることを特徴とするアルカリ金属分離回収装置。 (15) An alkali metal separation and recovery device for separating permeated water containing alkali metal from raw water containing alkali metal using a nanofiltration membrane and recovering the alkali metal contained in the permeated water by post-treatment. The apparatus includes at least two nanofiltration membrane units, and the concentrated water line of the preceding nanofiltration membrane unit is connected to the supply water line of the subsequent nanofiltration membrane unit. Recovery device.
 本発明によって、様々な溶質が共存する水からリチウムやカリウムなどのアルカリ金属を効率的に回収することが可能となる。 The present invention makes it possible to efficiently recover alkali metals such as lithium and potassium from water in which various solutes coexist.
図1は、本発明に係る、アルカリ金属分離回収方法の一実施態様を示す概略フロー図である(上記実施態様(1)~(5))。FIG. 1 is a schematic flowchart showing one embodiment of the alkali metal separation and recovery method according to the present invention (the above embodiments (1) to (5)). 図2は、本発明に係る、ナノ濾過膜ユニットの2段目供給水を昇圧する一実施態様を示す概略フロー図である(上記実施態様(6))。FIG. 2 is a schematic flow diagram showing one embodiment of pressurizing the second-stage feed water of the nanofiltration membrane unit according to the present invention (the above embodiment (6)). 図3は、本発明に係る、ナノ濾過膜の透過水を濃縮処理してからアルカリ金属を分離回収する方法の一実施態様を示す概略フロー図である(上記実施態様(7)及び(8))。FIG. 3 is a schematic flowchart showing one embodiment of a method for separating and recovering alkali metal after concentrating the permeated water of the nanofiltration membrane according to the present invention (the above embodiments (7) and (8)). ). 図4は、本発明に係る、ナノ濾過膜ユニットの最終段透過水を濃縮処理してから精製阻害物質を除去した上で、アルカリ金属を分離回収する方法の一実施態様を示す概略フロー図である(上記実施態様(9))。FIG. 4 is a schematic flow diagram showing an embodiment of a method for separating and recovering alkali metal after removing the purification inhibitor after concentrating the final permeate of the nanofiltration membrane unit according to the present invention. Yes (the above embodiment (9)). 図5は、本発明に係る、ナノ濾過膜の供給水に酸を添加する一実施態様を示す概略フロー図である(上記実施態様(10))。FIG. 5 is a schematic flow diagram showing one embodiment of adding an acid to the feed water of the nanofiltration membrane according to the present invention (the above embodiment (10)). 図6は、本発明に係る、ナノ濾過膜の最終濃縮水から精製阻害物質を除去した上で、アルカリ金属を含有する原水に還流する一実施態様を示す概略フロー図である(上記実施態様(11))。FIG. 6 is a schematic flow diagram showing an embodiment in which the purification inhibitor is removed from the final concentrated water of the nanofiltration membrane according to the present invention and then refluxed to the raw water containing the alkali metal (the above embodiment ( 11)). 図7は、本発明に係る、ナノ濾過膜の供給水に希釈水を混合する一実施態様を示す概略フロー図である(上記実施態様(12))。FIG. 7 is a schematic flow diagram showing one embodiment of mixing diluted water with the feed water of the nanofiltration membrane according to the present invention (the above embodiment (12)). 図8は、本発明に係る、ナノ濾過膜の透過水を濃縮処理して産生された透過水をナノ濾過膜供給水の希釈に用いる一実施態様を示す概略フロー図である(上記実施態様(13))。FIG. 8 is a schematic flow diagram showing an embodiment in which the permeated water produced by concentrating the permeated water of the nanofiltration membrane according to the present invention is used for dilution of the nanofiltration membrane feed water (the above embodiment ( 13)). 図9は、本発明に係る、ナノ濾過膜の供給水を加温する一実施態様を示す概略フロー図である(上記実施態様(14))。FIG. 9 is a schematic flow diagram showing one embodiment of heating the feed water of the nanofiltration membrane according to the present invention (the above embodiment (14)).
 以下、本発明の望ましい実施の形態の一例として、ナノ濾過膜ユニットが2段の場合を例にして、図面を用いて説明する。ただし、本発明はナノ濾過膜ユニットの段数を3段以上にすることも可能であるし、本発明の範囲はこれらの実施態様に限られるものではない。 Hereinafter, as an example of a preferred embodiment of the present invention, a case where the nanofiltration membrane unit has two stages will be described as an example with reference to the drawings. However, in the present invention, the number of nanofiltration membrane units can be three or more, and the scope of the present invention is not limited to these embodiments.
 本発明のアルカリ金属回収の実施フローの一例を図1に示す。図1に示すアルカリ金属回収装置では、アルカリ金属を含有する原水1が原水タンク2で一旦貯留された後、原水供給ポンプ4によって前処理ユニット3で処理され、前処理された原水は昇圧ポンプ5で1段目ナノ濾過膜ユニット6に送られ、アルカリ金属が透過分離される。1段目ナノ濾過膜ユニット6の濃縮水は、2段目ナノ濾過膜ユニット7に送られ、1段目と同様にアルカリ金属が透過分離され、最終濃縮水8は系外に排出される。ナノ濾過膜透過水は、回収ユニット9に送られ、アルカリ金属が回収される(上記実施態様(1))。 An example of the execution flow of the alkali metal recovery of the present invention is shown in FIG. In the alkali metal recovery apparatus shown in FIG. 1, raw water 1 containing alkali metal is temporarily stored in a raw water tank 2 and then processed by a pretreatment unit 3 by a raw water supply pump 4. Is sent to the first-stage nanofiltration membrane unit 6 to permeate and separate the alkali metal. The concentrated water of the first-stage nanofiltration membrane unit 6 is sent to the second-stage nanofiltration membrane unit 7, the alkali metal is permeated and separated as in the first stage, and the final concentrated water 8 is discharged out of the system. The nanofiltration membrane permeated water is sent to the recovery unit 9, and the alkali metal is recovered (the above embodiment (1)).
 本発明の対象となるアルカリ金属は、少なくともリチウムを含むものであれば好ましく、本発明の方法を実施する塩湖かん水などにおいては、リチウム以外にナトリウム、カリウム、ルビジウム、セシウムなどのアルカリ金属のうち少なくとも一つの金属と、マグネシウム、カルシウム、ストロンチウムなどのアルカリ土類金属の他、典型元素(アルミニウム、スズ、鉛など)、遷移元素(鉄、銅、コバルト、マンガンなど)、および1種以上の共役塩基(例えば塩化物イオン、硝酸イオン、硫酸イオン、炭酸イオン、酢酸イオンなど)との塩からなる化合物が溶存している。これらの各成分の濃度は特に限定されないが、分離回収の効率の点からリチウムイオン濃度が0.5ppm以上10000ppm以下の範囲であることが好ましく、より好ましくは5ppm以上5000ppm以下の範囲であり、さらに好ましくは50ppm以上2000ppm以下の範囲である水溶液を原水とすることが好ましい。必要に応じて濃縮や希釈などの処理により、原水として供することが可能である。 The alkali metal that is the subject of the present invention is preferably one containing at least lithium, and in salt lake brine etc. for carrying out the method of the present invention, among alkali metals such as sodium, potassium, rubidium, cesium and the like in addition to lithium. At least one metal, alkaline earth metal such as magnesium, calcium, strontium, typical elements (aluminum, tin, lead, etc.), transition elements (iron, copper, cobalt, manganese, etc.), and one or more conjugates A compound composed of a salt with a base (for example, chloride ion, nitrate ion, sulfate ion, carbonate ion, acetate ion, etc.) is dissolved. The concentration of each of these components is not particularly limited, but the lithium ion concentration is preferably in the range of 0.5 ppm or more and 10,000 ppm or less, more preferably in the range of 5 ppm or more and 5000 ppm or less, and more preferably, from the viewpoint of the efficiency of separation and recovery. Is preferably an aqueous solution in the range of 50 ppm to 2000 ppm. It can be used as raw water by treatment such as concentration and dilution as necessary.
 ここで、例えば炭酸リチウムや塩化カリウムなど、所望の精製アルカリ金属塩を分離回収するにあたり、その精製阻害物質としては難溶性塩を生成しやすいアルカリ土類金属塩や硫酸塩、地殻中の有機物などが挙げられ、マグネシウム塩および/または硫酸塩などが例示される。本発明では、アルカリ金属塩水溶液から精製アルカリ金属塩を分離回収する効率の観点から、原水となるアルカリ金属塩水溶液中のマグネシウムイオン濃度がリチウムイオン濃度に比して1000倍以下であることが好ましく、より好ましくは500倍以下、さらに好ましくは100倍以下であると効率的である。 Here, when separating and recovering a desired purified alkali metal salt such as lithium carbonate or potassium chloride, alkaline earth metal salts and sulfates that easily generate hardly soluble salts as the purification inhibitor, organic substances in the crust, etc. And magnesium salts and / or sulfates are exemplified. In the present invention, from the viewpoint of the efficiency of separating and recovering the purified alkali metal salt from the alkali metal salt aqueous solution, the magnesium ion concentration in the alkali metal salt aqueous solution serving as raw water is preferably 1000 times or less as compared with the lithium ion concentration. More preferably, it is efficient when it is 500 times or less, and more preferably 100 times or less.
 本発明では、分離膜で精製阻害物質を除去する処理工程を行うにあたり、アルカリ金属塩を含む水溶液中のマグネシウムイオン濃度が、該水溶液中のリチウムイオン濃度に比して7倍以下となるまで、分離膜による除去処理を行うことが好ましい。この比が7倍を超えると、精製アルカリ金属塩の回収効率が著しく低下する。なお、この時の精製阻害物質重量は、マグネシウムイオンや硫酸イオンなどのイオン換算重量で計算される。また、リチウムイオン換算重量および精製阻害物質重量は、例えばイオンクロマトグラフ測定によりアルカリ金属塩を含む水溶液の各種イオン濃度を定量することで求められる。 In the present invention, when performing the treatment step of removing the purification inhibitor with the separation membrane, the magnesium ion concentration in the aqueous solution containing the alkali metal salt is 7 times or less than the lithium ion concentration in the aqueous solution. It is preferable to perform a removal treatment using a separation membrane. If this ratio exceeds 7 times, the recovery efficiency of the purified alkali metal salt is significantly reduced. The weight of the purification inhibiting substance at this time is calculated based on the weight in terms of ions such as magnesium ions and sulfate ions. The weight in terms of lithium ion and the weight of the purification inhibitor can be determined by quantifying various ion concentrations in an aqueous solution containing an alkali metal salt, for example, by ion chromatography.
 原水中の精製阻害物質の含有量は、精製阻害物質の組成や濃度は原水の性状によって異なるが、例えば塩湖かん水ではマグネシウムイオン、硫酸イオンがそれぞれ100ppm以上30000ppm以下の範囲で含んでいる。 The content of the purification inhibitor in the raw water is different depending on the composition and concentration of the purification inhibitor depending on the properties of the raw water. For example, salt lake brine contains magnesium ions and sulfate ions in the range of 100 ppm to 30,000 ppm.
 ここでいうナノ濾過膜とは、IUPACで「2nmより小さい程度の粒子や高分子が阻止される圧力駆動の膜」と定義される膜であるが、本発明への適用に効果的なナノ濾過膜は、膜表面に荷電を有し、細孔による分離(サイズ分離)と膜表面の荷電による静電気的な分離の組み合わせによって特にイオンの分離効率を向上させたものが好ましく、回収目的とするアルカリ金属イオンとそのほかの荷電特性が異なるイオンを荷電によって分離しつつ、サイズ分離による高分子類の除去が可能なナノ濾過膜を適用することが好ましい。 The nanofiltration membrane referred to here is a membrane defined by IUPAC as “a pressure-driven membrane in which particles and polymers of a size smaller than 2 nm are blocked”, but is effective for application to the present invention. Preferably, the membrane has a charge on the membrane surface, and has improved ion separation efficiency by a combination of separation by pores (size separation) and electrostatic separation by charge on the membrane surface. It is preferable to apply a nanofiltration membrane that is capable of removing polymers by size separation while separating metal ions and other ions having different charge characteristics by charging.
 本発明に適した分離膜としては、特に0.5MPaの操作圧力で25℃、pH6.5の1000ppmイソプロピルアルコール水溶液および25℃、pH6.5の1000ppmグルコース水溶液をそれぞれ透過させた時のグルコース除去率が90%以上であり、かつ、グルコース除去率とイソプロピルアルコール除去率の差が30%以上であるナノ濾過膜を用いることで、総塩濃度によらずアルカリ金属塩、中でもリチウム塩と精製阻害物質の分離が極めて高効率で達成されるため特に好ましい。 As a separation membrane suitable for the present invention, the glucose removal rate is particularly good when permeating a 1000 ppm isopropyl alcohol aqueous solution of 25 ° C. and pH 6.5 and a 1000 ppm glucose aqueous solution of 25 ° C. and pH 6.5 at an operating pressure of 0.5 MPa. By using a nanofiltration membrane that is 90% or more and the difference between the glucose removal rate and the isopropyl alcohol removal rate is 30% or more, alkali metal salts, especially lithium salts and purification inhibitors, are not affected by the total salt concentration. Separation is particularly preferred because it is achieved with very high efficiency.
 さらに、一般に、前記精製アルカリ金属塩は水溶液の濃縮や加熱、冷却、または核化剤の添加などで誘起される、晶析操作によって分離回収が可能であることから、これらを阻害するマグネシウム塩および/または硫酸塩が除去されることが好ましい。そこで、0.5MPaの操作圧力で25℃、pH6.5の2000ppm硫酸マグネシウム水溶液および25℃、pH6.5の2000ppm塩化リチウム水溶液をそれぞれ透過させた時の硫酸マグネシウム除去率が90%以上、好ましくは95%以上、さらに好ましくは97%以上であり、かつ、塩化リチウム除去率が70%以下、好ましくは50%以下、さらに好ましくは30%以下であるナノ濾過膜を用いることで、総塩濃度によらずリチウム塩と精製阻害物質の分離が極めて高効率で達成される。また、本発明の分離膜による工程の後にアルカリ金属塩の濃縮によって精製アルカリ金属塩の回収を行うことが好ましい。 Furthermore, in general, the purified alkali metal salt can be separated and recovered by a crystallization operation induced by concentration of an aqueous solution, heating, cooling, or addition of a nucleating agent. It is preferred that the sulfate is removed. Therefore, the removal rate of magnesium sulfate is 90% or more when passing through a 2000 ppm magnesium sulfate aqueous solution at 25 ° C. and pH 6.5 and a 2000 ppm lithium chloride aqueous solution at 25 ° C. and pH 6.5 at an operating pressure of 0.5 MPa, preferably 95%. % Or more, more preferably 97% or more, and using a nanofiltration membrane having a lithium chloride removal rate of 70% or less, preferably 50% or less, more preferably 30% or less, depending on the total salt concentration. Separation of lithium salt and purification inhibitor is achieved with extremely high efficiency. Further, it is preferable to recover the purified alkali metal salt by concentration of the alkali metal salt after the step of the separation membrane of the present invention.
 精製アルカリ金属塩の回収は、例えばカリウム塩の場合、溶解度の温度依存性を利用、またはエタノールなどの貧溶媒を添加して塩化カリウムを回収する公知の方法で回収を行う。リチウム塩の場合は、他のアルカリ金属塩に比べて溶解度が小さいことを利用して、例えば炭酸塩を水溶液に添加することで炭酸リチウムとして回収する。これは炭酸ナトリウムや炭酸カリウムは水への溶解度が十分高い(水100mLに対し20g以上)ことに対し、炭酸リチウムの溶解度が25℃で水100mL対して1.33gしか溶けず、さらに高温では溶解度が低下することを利用したものである。 For the recovery of the purified alkali metal salt, for example, in the case of a potassium salt, the temperature dependency of the solubility is used, or recovery is performed by a known method of recovering potassium chloride by adding a poor solvent such as ethanol. In the case of a lithium salt, it is recovered as lithium carbonate, for example, by adding a carbonate to an aqueous solution, taking advantage of its low solubility compared to other alkali metal salts. This is because sodium carbonate and potassium carbonate have a sufficiently high solubility in water (20 g or more per 100 mL of water), whereas the solubility of lithium carbonate is only 1.33 g per 100 mL of water at 25 ° C, and the solubility is higher at higher temperatures. It uses the decline.
 また、ナノ濾過膜ユニットは、ナノ濾過膜をモジュール化したものから構成され、例えば、スパイラル型のナノ濾過膜エレメントを単数もしくは複数連結して容器に収納したものやそれを直列や並列に接続したものを指す。 In addition, the nanofiltration membrane unit is composed of a modularized nanofiltration membrane, for example, one or a plurality of spiral nanofiltration membrane elements connected in a container and connected in series or in parallel. Refers to things.
 回収ユニット9でアルカリ金属を回収した後の低濃度水11は、排水することもできれば、そのアルカリ金属含有量によっては、原水に還流させることも可能である。また、ナノ濾過膜の最終濃縮水8は、圧力エネルギーを有しているため、エネルギー回収ユニットを適用すれば、省エネルギーになるため好ましい。 The low-concentration water 11 after the alkali metal is recovered by the recovery unit 9 can be drained or returned to the raw water depending on the alkali metal content. Moreover, since the final concentrated water 8 of the nanofiltration membrane has pressure energy, it is preferable to apply an energy recovery unit because it saves energy.
 前処理ユニット3は、特に制約されるものではなく、原水性状によって、濁質成分の除去や殺菌など適宜選択することができる。 The pretreatment unit 3 is not particularly limited, and can be appropriately selected depending on the raw aqueous state, such as removal of turbid components and sterilization.
 供給水の濁質を除去する必要がある場合は、砂濾過や精密濾過膜、限外濾過膜の適用が効果的である。このときバクテリアや藻類などの微生物が多い場合は、殺菌剤を添加することも好ましい。殺菌剤としては塩素を用いることが好ましく、たとえば塩素ガスや次亜塩素酸ナトリウムを遊離塩素として1~5mg/lの範囲内となるように供給水に添加するとよい。なお、半透膜によっては特定の殺菌剤に化学的な耐久性がない場合があるので、その場合は、なるべく供給水の上流側で添加し、さらに、半透膜ユニットの供給水入口側近傍にて殺菌剤を無効にすることが好ましい。例えば、遊離塩素の場合は、その濃度を測定し、この測定値に基づいて塩素ガスや次亜塩素酸ナトリウムの添加量を制御したり、亜硫酸水素ナトリウムなどの還元剤を添加したりするとよい。 ∙ When it is necessary to remove the turbidity of supply water, it is effective to apply sand filtration, microfiltration membrane, or ultrafiltration membrane. At this time, when there are many microorganisms such as bacteria and algae, it is also preferable to add a bactericidal agent. Chlorine is preferably used as the disinfectant, and for example, chlorine gas or sodium hypochlorite may be added to the feed water as free chlorine so as to be in the range of 1 to 5 mg / l. Depending on the semipermeable membrane, certain fungicides may not have chemical durability. In that case, add as much upstream as possible to the feed water, and further, near the feed water inlet side of the semipermeable membrane unit. It is preferable to disable the disinfectant. For example, in the case of free chlorine, its concentration is measured, and the addition amount of chlorine gas and sodium hypochlorite is controlled based on this measured value, or a reducing agent such as sodium bisulfite is added.
 また、濁質以外にバクテリアやタンパク質、天然有機成分などを含有する場合は、ポリ塩化アルミニウム、硫酸バンド、塩化鉄(III)などの凝集剤を加えることも効果的である。 In addition, in the case of containing bacteria, proteins, natural organic components, etc. in addition to turbid substances, it is also effective to add a flocculant such as polyaluminum chloride, sulfate band, iron (III) chloride.
 凝集させた供給水は、その後に斜向板などで沈降させた上で砂濾過を行ったり、複数本の中空糸膜を束ねた精密濾過膜や限外濾過膜による濾過を行ったりすることによって後段の半透膜ユニットを通過させるのに適した供給水とすることができる。特に、凝集剤の添加にあたっては、凝集しやすいようにpHを調整することが好ましい。 The agglomerated supply water is then subjected to sand filtration after settling on an inclined plate or the like, or by filtration through a microfiltration membrane or an ultrafiltration membrane in which a plurality of hollow fiber membranes are bundled. Supply water suitable for passing through the latter semipermeable membrane unit can be obtained. In particular, when adding the flocculant, it is preferable to adjust the pH so as to facilitate aggregation.
 ここで、前処理に砂濾過を用いる場合は、自然に流下する方式の重力式濾過を適用することもできれば、加圧タンクの中に砂を充填した加圧式濾過を適用することも可能である。充填する砂も、単一成分の砂を適用することが可能であるが、例えば、アンスラサイト、珪砂、ガーネット、軽石など、を組み合わせて、濾過効率を高めることが可能である。精密濾過膜や限外濾過膜についても、特に制約はなく、平膜、中空糸膜、管状型膜、プリーツ型、その他いかなる形状のものも適宜用いることができる。膜の素材についても、特に限定されるものではなく、ポリアクリロニトリル、ポリフェニレンスルフォン、ポリフェニレンスルフィドスルフォン、ポリフッ化ビニリデン、ポリプロピレン、ポリエチレン、ポリスルホン、ポリビニルアルコール、酢酸セルロースや、セラミック等の無機素材を用いることができる。また、濾過方式にしても供給水を加圧して濾過する加圧濾過方式や透過側を吸引して濾過する吸引濾過方式のいずれも適用可能である。特に、吸引濾過方式の場合は、凝集沈殿槽や生物処理槽に精密濾過膜や限外濾過膜を浸漬して濾過する、いわゆる凝集膜濾過や膜利用活性汚泥法(MBR)を適用することも好ましい。 Here, when sand filtration is used for pretreatment, it is possible to apply gravity-type filtration that naturally flows down, or it is possible to apply pressure-type filtration in which a pressure tank is filled with sand. . As the sand to be filled, single-component sand can be applied. For example, anthracite, silica sand, garnet, pumice, and the like can be combined to increase filtration efficiency. The microfiltration membrane and the ultrafiltration membrane are not particularly limited, and a flat membrane, a hollow fiber membrane, a tubular membrane, a pleated shape, or any other shape can be used as appropriate. The material of the membrane is not particularly limited, and it is possible to use an inorganic material such as polyacrylonitrile, polyphenylene sulfone, polyphenylene sulfide sulfone, polyvinylidene fluoride, polypropylene, polyethylene, polysulfone, polyvinyl alcohol, cellulose acetate, or ceramic. it can. Moreover, even if it is a filtration system, any of the pressure filtration system which pressurizes and filters supply water, and the suction filtration system which sucks and filters the permeation | transmission side are applicable. In particular, in the case of a suction filtration method, so-called agglomerated membrane filtration or membrane-based activated sludge method (MBR), in which a microfiltration membrane or an ultrafiltration membrane is immersed in a coagulation sedimentation tank or a biological treatment tank for filtration, may be applied. preferable.
 一方、供給水に溶解性の有機物が多く含まれている場合は、塩素ガスや次亜塩素酸ナトリウムの添加によってそれら有機物を分解することができるが、加圧浮上や活性炭濾過を行うことによっても除去が可能である。また、溶解性の無機物が多く含まれている場合は、有機系高分子電解質やヘキサメタ燐酸ソーダなどのキレート剤を添加したり、イオン交換樹脂などを用いて溶解性イオンと交換したりするとよい。また、鉄やマンガンが可溶な状態で存在しているときは、ばっ気酸化濾過法や接触酸化濾過法などを用いることが好ましい。 On the other hand, when the supply water contains a lot of soluble organic matter, the organic matter can be decomposed by adding chlorine gas or sodium hypochlorite. Removal is possible. In addition, when a large amount of soluble inorganic substance is contained, a chelating agent such as an organic polymer electrolyte or sodium hexametaphosphate may be added, or exchanged with soluble ions using an ion exchange resin or the like. In addition, when iron or manganese is present in a soluble state, it is preferable to use an aeration oxidation filtration method or a contact oxidation filtration method.
 ナノ濾過膜ユニットに関しては、1段目から最終段まで異なるようにすることが好ましい(上記実施態様(2))。ナノ濾過膜ユニットが異なるようにするためには、ナノ濾過膜を異なるようにすることが簡便である。本発明においてアルカリ金属を効率的に透過させて他の溶質を阻止するために、ナノ濾過膜の各段において徐々に変化する供給水質に応じて、ナノ濾過膜の分画分子量や荷電特性を最適化することによって分離効率を高めることが可能となる。特に、前段から後段になるに従って、流動抵抗による圧力損失や供給水濃度の上昇による有効濾過圧力減少によって、透過量が減少するため、後段のナノ濾過膜の純水透水性能が前段よりも大きい方が好ましい(上記実施態様(3))。 It is preferable that the nanofiltration membrane unit is different from the first stage to the last stage (the above embodiment (2)). In order to make the nanofiltration membrane units different, it is convenient to make the nanofiltration membranes different. In order to efficiently permeate alkali metals and block other solutes in the present invention, the molecular weight and charge characteristics of the nanofiltration membrane are optimized according to the water supply quality gradually changing at each stage of the nanofiltration membrane. Therefore, it is possible to increase the separation efficiency. In particular, since the permeation amount decreases due to the pressure loss due to flow resistance and the decrease in effective filtration pressure due to the increase in feed water concentration from the previous stage to the latter stage, the pure water permeability performance of the latter nanofiltration membrane is larger than the previous stage. Is preferable (the above embodiment (3)).
 ここでいう純水送水性能とは、ナノ濾過膜に圧力(通常0.3~0.5MPa)をかけた純水を透過させることによって測定することができ、標準温度(通常25℃)において単位膜面積、単位時間あたりに透過した水の量を測定して得られる値である。 The pure water feeding performance here can be measured by allowing pure water applied with pressure (usually 0.3 to 0.5 MPa) to pass through the nanofiltration membrane, and is measured at a standard temperature (usually 25 ° C.). It is a value obtained by measuring the membrane area and the amount of water permeated per unit time.
 さらに、供給水の濃度は後段ほど上昇するが、アルカリ金属イオンは少なくない量がナノ濾過膜を透過するため、後段の供給水ほどアルカリ金属濃度に対するその他の溶質(アルカリ土類金属や硫酸イオンのような多価イオン)濃度の比率が高くなり、透過水のアルカリ金属含有率も前段より低下する。そのため、後段ほど分離性能の高いナノ濾過膜を用いることが好ましい。具体的には、アルカリ金属透過率に対する硫酸イオン透過率の比について、第1段のナノ濾過膜ユニットにおける比が最終段のナノ濾過膜ユニットにおける比よりも小さくすることによって、本発明をより効率的に実現することが可能となる(上記実施態様(4))。このようなナノ濾過膜は、前段よりも後段のナノ濾過膜の表面荷電を強くしつつ、細孔径(分画分子量)を大きめにすることによって、実現することができる。表面荷電を強くする方法としては、例えば、文献(Photoinduced grafting of ultrafiltration membranes: comparison of poly(ether sulfone) and poly(sulfone), B. Kaeselevら,ジャーナルオブメンブレンサイエンス)に示されるように膜表面にUV、また、電子線、プラズマなどでラジカル(活性点)をつくってグラフト重合させるといった方法や、酸化剤などで高分子鎖を断裂するなどの方法が例として挙げられる。また、本発明に適用するナノ濾過膜としては、透水性能と分離性能を両立し、総合的な膜性能のポテンシャルが高いという観点から、多官能アミンと多官能酸ハロゲン化物との重縮合反応により得られる架橋ポリアミドの超薄膜層を微多孔性支持膜上に有してなる複合半透膜であることが好ましい。 In addition, the concentration of the feed water increases as the latter stage, but not a small amount of alkali metal ions permeate the nanofiltration membrane, so that the latter feed water contains other solutes (alkaline earth metals and sulfate ions) with respect to the alkali metal concentration. The ratio of such multivalent ions) is increased, and the alkali metal content of the permeated water is also decreased from the previous stage. Therefore, it is preferable to use a nanofiltration membrane with higher separation performance as the latter stage. Specifically, regarding the ratio of the sulfate ion permeability to the alkali metal permeability, the ratio of the first-stage nanofiltration membrane unit is smaller than the ratio of the final-stage nanofiltration membrane unit, thereby making the present invention more efficient. (Embodiment (4) above). Such a nanofiltration membrane can be realized by increasing the pore diameter (fractionated molecular weight) while increasing the surface charge of the latter nanofiltration membrane as compared with the previous stage. As a method for increasing the surface charge, for example, as shown in the literature (Photoinduced grafting of ultrafiltration membranes: comparison of poly (ether sulfone) and poly (sulfone), B. Kaeselev et al., Journal of Membrane Science) Examples thereof include a method in which radicals (active sites) are produced by UV, electron beam, plasma, etc., and graft polymerization is performed, and a method in which a polymer chain is cleaved with an oxidizing agent or the like. In addition, as a nanofiltration membrane applied to the present invention, a polycondensation reaction between a polyfunctional amine and a polyfunctional acid halide is performed from the viewpoint of achieving both high water permeability and separation performance and high potential for comprehensive membrane performance. A composite semipermeable membrane having an ultrathin film layer of the obtained crosslinked polyamide on a microporous support membrane is preferred.
 さらに、高分離効率が求められる前段のナノ濾過膜ユニット内のナノ濾過膜は、脂肪族系ポリアミドを主成分(すなわち、脂肪族ポリアミドのアミド結合数が芳香族ポリアミドのアミド結合よりも多い。)として含むことが好ましく、高透過性能が求められる後段のナノ濾過膜ユニット内のナノ濾過膜としては、芳香族系ポリアミドを主成分として含むことが好ましい(上記実施態様(5))。 Furthermore, the nanofiltration membrane in the preceding nanofiltration membrane unit that requires high separation efficiency is mainly composed of aliphatic polyamide (that is, the number of amide bonds of aliphatic polyamide is larger than that of aromatic polyamide). The nanofiltration membrane in the latter nanofiltration membrane unit that requires high permeation performance preferably contains aromatic polyamide as a main component (the above embodiment (5)).
 脂肪族アミンとしては、[I]式に示すようなピペラジン系アミン及びその誘導体が好ましく、ピペラジン、2,5-ジメチルピペラジン、2-メチルピペラジン、2,6-ジメチルピペラジン、2,3,5-トリメチルピペラジン、2,5-ジエチルピペラジン、2,3,5-トリエチルピペラジン、2-n-プロピルピペラジン、2,5-ジ-n-ブチルピペラジンなどが例示される。中でもより高い溶質除去性能、水透過性能を有するナノ濾過膜を幅広い組成比で得ることができるピペラジンや2,5-ジメチルピペラジンを用いることが特に好ましい。 As the aliphatic amine, piperazine-based amines and derivatives thereof represented by the formula [I] are preferable, and piperazine, 2,5-dimethylpiperazine, 2-methylpiperazine, 2,6-dimethylpiperazine, 2,3,5- Examples include trimethylpiperazine, 2,5-diethylpiperazine, 2,3,5-triethylpiperazine, 2-n-propylpiperazine, 2,5-di-n-butylpiperazine and the like. Among them, it is particularly preferable to use piperazine or 2,5-dimethylpiperazine, which can obtain a nanofiltration membrane having higher solute removal performance and water permeation performance with a wide composition ratio.
Figure JPOXMLDOC01-appb-C000001
Figure JPOXMLDOC01-appb-C000001
[I]式中、R1~R8はH,OH,COOH,SOH,NHまたはC1~C4の直鎖状あるいは環状の飽和、不飽和脂肪族基のいずれかから選ばれる。 [I] In the formula, R1 to R8 are selected from H, OH, COOH, SO 3 H, NH 2 or C1 to C4 linear or cyclic saturated or unsaturated aliphatic groups.
 芳香族系ポリアミドの場合、多官能アミンとしては、一分子中に2個以上のアミノ基を有するアミンであり、オルト位(o-)に2個のアミノ基を有するo-芳香族ジアミンを含むものが好ましい。さらに多官能アミンとしては、メタ位(m-)に2個のアミノ基を有するm-芳香族ジアミン、パラ位(p-)に2個のアミノ基を有するp-芳香族ジアミンならびに脂肪族系アミンおよびその誘導体からなる群から選ばれる少なくとも1種、中でも、緻密で剛直な構造を有するために阻止性能と透水性能のポテンシャルに優れ、さらに耐久性、特に耐熱性に優れた膜を得ることが容易なm-芳香族ジアミンやp-芳香族ジアミンを含んでいることも好ましい。 In the case of an aromatic polyamide, the polyfunctional amine is an amine having two or more amino groups in one molecule, and includes an o-aromatic diamine having two amino groups in the ortho position (o-). Those are preferred. Further, the polyfunctional amines include m-aromatic diamines having two amino groups at the meta position (m-), p-aromatic diamines having two amino groups at the para position (p-), and aliphatic systems. At least one selected from the group consisting of amines and derivatives thereof, and in particular, having a dense and rigid structure, can provide a membrane having excellent blocking performance and water permeability performance, and further excellent durability and particularly heat resistance. It is also preferable that an easy m-aromatic diamine or p-aromatic diamine is contained.
 ここで、o-芳香族ジアミンとして好ましく用いられるのはo-フェニレンジアミンである。m-芳香族ジアミンとしては、m-フェニレンジアミンが好ましいが、3,5-ジアミノ安息香酸や2,6-ジアミノピリジン等を用いることもできる。p-芳香族ジアミンとしてはp-フェニレンジアミンが好ましいが、2,5-ジアミノベンゼンスルホン酸やp-キシリレンジアミン等を用いることもできる。 Here, o-phenylenediamine is preferably used as the o-aromatic diamine. As the m-aromatic diamine, m-phenylenediamine is preferable, but 3,5-diaminobenzoic acid, 2,6-diaminopyridine and the like can also be used. As the p-aromatic diamine, p-phenylenediamine is preferable, but 2,5-diaminobenzenesulfonic acid, p-xylylenediamine and the like can also be used.
 これら多官能アミンの製膜原液中におけるモル比は、用いるアミンおよび酸ハロゲン化物によって適宜最適な組成比を選ぶことができるが、o-芳香族ジアミンの添加比率が高いほど透水性は向上し、反面、溶質全体の阻止性能は低下する。また、脂肪族多官能アミンを多くすることで、多価イオンと一価イオンの分離性能が向上する。これによって目的とする透水性能とイオン分離性能、溶質全体の阻止性能を満足する本発明の液体分離膜を得ることが可能となる。 The molar ratio of these polyfunctional amines in the film-forming stock solution can be appropriately selected depending on the amine and acid halide used. However, the higher the addition ratio of o-aromatic diamine, the better the water permeability. On the other hand, the blocking performance of the entire solute is reduced. Moreover, the separation performance of multivalent ions and monovalent ions is improved by increasing the number of aliphatic polyfunctional amines. This makes it possible to obtain the liquid separation membrane of the present invention that satisfies the desired water permeation performance, ion separation performance, and blocking performance of the entire solute.
 また、アミン成分として脂肪族アミンが多いと耐熱安定性が低下するため、耐熱性を重視したい場合は、脂肪族アミンを少なくすることによって耐熱性の向上を達成することもできる。 In addition, when there are a large number of aliphatic amines as the amine component, the heat stability is lowered. Therefore, when heat resistance is important, the heat resistance can be improved by reducing the number of aliphatic amines.
 一方、多官能酸ハロゲン化物としては、一分子中に2個以上のハロゲン化カルボニル基を有する酸ハロゲン化物や多官能酸無水物ハロゲン化物で、上記多官能アミンとの反応により架橋ポリアミドの分離機能層を形成するものであれば特に限定されるものではない。例えば1,3,5-シクロヘキサントリカルボン酸、1,3-シクロヘキサンジカルボン酸、1,4-シクロヘキサンジカルボン酸、1,3,5-ベンゼントリカルボン酸、1,2,4-ベンゼントリカルボン酸、1,3-ベンゼンジカルボン酸、1,4-ベンゼンジカルボン酸の酸ハロゲン化物の混合物などである。中でも、製膜性が良好で、全溶質阻止性能が均質で欠陥やばらつきの少ない膜を得やすい、[II]式、[III]式で表されるジカルボン酸やトリカルボン酸が好ましく、とくに、経済性、取り扱い易さ、反応の容易さ等の点から、1,3,5-ベンゼントリカルボン酸の酸ハロゲン化物であるトリメシン酸クロライドが好ましい。 On the other hand, polyfunctional acid halides are acid halides or polyfunctional acid anhydride halides having two or more carbonyl halide groups in one molecule, and the function of separating crosslinked polyamide by reaction with the above polyfunctional amine. There is no particular limitation as long as it forms a layer. For example, 1,3,5-cyclohexanetricarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,3 -A mixture of benzenedicarboxylic acid and acid halide of 1,4-benzenedicarboxylic acid. Among them, dicarboxylic acids and tricarboxylic acids represented by the formulas [II] and [III] are preferable, particularly good for economics, because the film-forming property is good, the entire solute blocking performance is uniform, and there are few defects and variations. From the viewpoints of properties, ease of handling, reaction, and the like, trimesic acid chloride, which is an acid halide of 1,3,5-benzenetricarboxylic acid, is preferable.
Figure JPOXMLDOC01-appb-C000002
Figure JPOXMLDOC01-appb-C000002
[II]式中、RはHまたはC1~C3の炭化水素から選ばれる。 [II] In the formula, R is selected from H or a C1-C3 hydrocarbon.
Figure JPOXMLDOC01-appb-C000003
Figure JPOXMLDOC01-appb-C000003
[III]式中、RはHまたはC1~C3の炭化水素から選ばれる。 [III] In the formula, R is selected from H or a C1-C3 hydrocarbon.
 また、多官能酸無水物ハロゲン化物としては、一分子中に1個以上の酸無水物部分と1個以上のハロゲン化カルボニル基を有し、無水安息香酸、無水フタル酸のカルボニルハロゲン化物である、下記一般式[IV]で表されるトリメリット酸無水物ハロゲン化物及びその誘導体が好ましく用いられる。 The polyfunctional acid anhydride halide is a carbonyl halide of benzoic anhydride or phthalic anhydride having one or more acid anhydride moieties and one or more halogenated carbonyl groups in one molecule. Trimellitic anhydride halides and derivatives thereof represented by the following general formula [IV] are preferably used.
Figure JPOXMLDOC01-appb-C000004
Figure JPOXMLDOC01-appb-C000004
[IV]式中、X1およびX2は、C1~C3の直鎖状あるいは環状の飽和、不飽和脂肪族基、H,OH,COOH,SOH,COF,COCl,COBr,COIのいずれかから選ばれる。または、X1とX2との間で酸無水物を形成していても良い。X3はC1~C3の直鎖状あるいは環状の飽和、不飽和脂肪族基、H,OH,COOH,SOH,COF,COCl,COBr,COIのいずれかから選ばれる。YはH,F,Cl,Br,IまたはC1~C3の炭化水素から選ばれる。 [IV] In the formula, X1 and X2 are any of C1 to C3 linear or cyclic saturated, unsaturated aliphatic group, H, OH, COOH, SO 3 H, COF, COCl, COBr, COI. To be elected. Alternatively, an acid anhydride may be formed between X1 and X2. X3 is selected from any of C1 to C3 linear or cyclic saturated or unsaturated aliphatic groups, H, OH, COOH, SO 3 H, COF, COCl, COBr, and COI. Y is selected from H, F, Cl, Br, I or C1-C3 hydrocarbons.
 ところで、前段と後段のナノ濾過膜を異なるようにする以外に、本発明の性能向上手段として、図2に例示するように中間昇圧をすることも好ましい。すなわち、前段の濃縮水を後段の供給水とするにあたって、ブースターポンプ12などで昇圧し、後段の処理性能を上げるという方法である(上記実施態様(6))。これによって、後段の透水性を実質的に上げることが可能となる。 Incidentally, in addition to making the front and rear nanofiltration membranes different from each other, it is also preferable to perform intermediate boosting as exemplified in FIG. 2 as the performance improvement means of the present invention. That is, when the upstream concentrated water is used as the downstream supply water, the pressure is increased by the booster pump 12 or the like to increase the downstream processing performance (the above embodiment (6)). This makes it possible to substantially increase the water permeability in the subsequent stage.
 本発明においては、ナノ濾過膜によってアルカリ金属が選択的に透過するものの、通常、その透過水濃度が原水以上の濃度になることはないため、後処理でアルカリ金属を効率的に回収するためには、ナノ濾過膜の透過水を濃縮する工程(透過水濃縮工程)を追加することも好ましい実施態様である(上記実施態様(7))。ここで、透過水濃縮工程は、例えば、蒸留、膜分離、吸脱着、イオン交換、など、様々な方法を挙げることができるが、アルカリ金属は不揮発性でサイズが非常に小さいため、蒸発法、膜蒸留法(膜を利用した純水分離・濃縮方法)、阻止性能が高い逆浸透膜を用いて濃縮すると効率的で好ましい(上記実施態様(8))。ここで、阻止性能が高い逆浸透膜とは、アルカリ金属除去率95%以上の逆浸透膜のことを指す。図3に濃縮ユニット14として逆浸透膜を用いた場合を例示する。ただし、ナノ濾過膜の後段になるほどアルカリ土類金属をはじめとする成分が濃縮され、その結果、透過水に含有するアルカリ土類金属の濃度が高くなるため、図4に例示するように、アルカリ土類金属除去ユニット17でアルカリ土類金属を除去してから後処理9でアルカリ金属を回収する方法も好ましい実施態様である(上記実施態様(9))。 In the present invention, although the alkali metal selectively permeates through the nanofiltration membrane, the permeate concentration usually does not become higher than that of the raw water, so that the alkali metal can be efficiently recovered in the post-treatment. It is also a preferred embodiment to add a step of concentrating the permeated water of the nanofiltration membrane (permeated water concentrating step) (the above embodiment (7)). Here, the permeated water concentration step can include various methods such as distillation, membrane separation, adsorption / desorption, and ion exchange, but the alkali metal is non-volatile and has a very small size. It is efficient and preferable to concentrate using a membrane distillation method (pure water separation / concentration method using a membrane) and a reverse osmosis membrane having high blocking performance (the above embodiment (8)). Here, the reverse osmosis membrane having high blocking performance refers to a reverse osmosis membrane having an alkali metal removal rate of 95% or more. FIG. 3 illustrates a case where a reverse osmosis membrane is used as the concentration unit 14. However, as the latter stage of the nanofiltration membrane, components such as alkaline earth metals are concentrated, and as a result, the concentration of the alkaline earth metal contained in the permeated water becomes higher. As illustrated in FIG. A method of removing the alkaline earth metal by the earth metal removal unit 17 and then recovering the alkali metal in the post-treatment 9 is also a preferred embodiment (the above embodiment (9)).
 ここで、淡水として透過水15が得られるが、これは系外に排出することも可能であるし、工程水その他として再利用することも可能である。 Here, permeated water 15 is obtained as fresh water, which can be discharged out of the system, or can be reused as process water and the like.
 本発明のようにナノ濾過膜を複数段構成する場合、濃縮水中のアルカリ土類金属濃度が次第に上がり、運転条件によってはスケールとなってナノ濾過膜の表面に析出し、ナノ濾過膜の性能を低下させたり、ナノ濾過膜を損傷させたりすることになるため、そのような危険性が予想される場合は、原水もしくは前段の濃縮水に酸を添加してpHを下げ、スケール析出を防止することが好ましい(上記実施態様(10))。もちろん、スケール防止剤を添加することも可能であるが、環境影響やスケール防止剤の万一の漏出などのリスクが発生するため、添加にあたっては注意が必要である。図5には後段の供給水(前段の濃縮水)に酸19を添加する場合の一実施態様を示す。 When the nanofiltration membrane is composed of a plurality of stages as in the present invention, the alkaline earth metal concentration in the concentrated water gradually increases, and depending on the operating conditions, it becomes a scale and precipitates on the surface of the nanofiltration membrane. If such a danger is expected, the pH is lowered by adding acid to the raw water or the concentrated water in the previous stage to prevent scale precipitation. It is preferable (the above embodiment (10)). Of course, it is possible to add a scale inhibitor. However, since there are risks such as environmental impact and possible leakage of the scale inhibitor, caution is required in the addition. FIG. 5 shows an embodiment in which the acid 19 is added to the feed water in the latter stage (concentrated water in the former stage).
 ナノ濾過膜の濃縮水8は、アルカリ土類金属などを高濃度に含有するが、一般には、アルカリ金属イオンが他の成分よりも比率は少ないものの原水濃度以上に含有しているため、例えば図6のように、アルカリ金属除去ユニット17でアルカリ土類金属を除去した後に、原水に還流することによって原水中のアルカリ金属の回収率を高めることができる(上記実施態様(11))。 The concentrated water 8 of the nanofiltration membrane contains an alkaline earth metal or the like at a high concentration, but generally contains alkali metal ions at a concentration higher than the raw water concentration although the ratio is smaller than other components. 6, after the alkaline earth metal is removed by the alkali metal removal unit 17, the recovery rate of the alkali metal in the raw water can be increased by refluxing the raw water (the above embodiment (11)).
 アルカリ金属の回収率を上げる他の方法としては、例えば図7のように、原水もしくはナノ濾過膜ユニットの供給水のいずれかに対して、希釈水20を混合する方法が挙げられる(上記実施態様(12))。これによって供給水の濃縮に起因する濃度上昇によって生じる分離効率の低下や溶解度を超えた成分の膜面への析出を防ぐことが可能となる。なお、希釈水20は、河川水、地下水、雨水などの自然水や水道水など、原水よりも低濃度の水を用いることができるが、図3,4に示すように濃縮ユニット14,14’の透過水15を用いると、効率的な水回収再利用ができるため非常に好ましい(上記実施態様(13);図8参照)。 As another method for increasing the recovery rate of alkali metal, for example, as shown in FIG. 7, there is a method of mixing the dilution water 20 with either the raw water or the feed water of the nanofiltration membrane unit (the above embodiment). (12)). As a result, it is possible to prevent the separation efficiency from being lowered due to the concentration increase caused by the concentration of the feed water and the precipitation of components exceeding the solubility on the membrane surface. The dilution water 20 may be water having a lower concentration than the raw water, such as natural water such as river water, ground water, rainwater, or tap water, but the concentration units 14 and 14 'as shown in FIGS. When the permeated water 15 is used, it is very preferable because the water can be efficiently recovered and reused (the embodiment (13); see FIG. 8).
 本発明の適用にあたっては、ナノ濾過膜の透水性能と分離性能が高いほど適用効果が高いが、そのためには、図9に例示するように、原水やナノ濾過膜供給水をあらかじめ加温しておくことが効率向上手段として好ましい。(上記実施態様(14))。熱源は特に制約されるものではないが、本発明適用システムに蒸発法や膜蒸留法などの廃熱、昇圧ポンプで生じる熱を利用して加温すると効率的である。 In applying the present invention, the higher the water permeation performance and separation performance of the nanofiltration membrane, the higher the application effect. To that end, as illustrated in FIG. 9, the raw water and the nanofiltration membrane supply water are heated in advance. It is preferable as a means for improving efficiency. (Embodiment (14) above). The heat source is not particularly limited, but it is efficient to heat the system to which the present invention is applied using waste heat such as an evaporation method or a membrane distillation method, or heat generated by a pressure pump.
 本発明を詳細にまた特定の実施態様を参照して説明したが、本発明の精神と範囲を逸脱することなく様々な変更や修正を加えることができることは、当業者にとって明らかである。
 本出願は、2010年12月6日出願の日本特許出願2010-271341に基づくものであり、その内容はここに参照として取り込まれる。
Although the invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application No. 2010-271341 filed on Dec. 6, 2010, the contents of which are incorporated herein by reference.
 本発明は、湖水、地下水、産業廃水などからリチウムやカリウムなどのアルカリ金属を回収する装置およびその運転方法に関するものであり、さらに詳しくは、複数段のナノ濾過膜を用いて効率的にアルカリ金属を回収するための装置およびその運転方法に関するものであり、複数段のナノ濾過膜によって濃縮,分離,回収が困難な多種の溶質が含まれる水からアルカリ金属を効率的な分離回収を実現することができる。 The present invention relates to an apparatus for recovering alkali metals such as lithium and potassium from lake water, groundwater, industrial wastewater, and the like, and more particularly to an alkali metal efficiently using a multi-stage nanofiltration membrane. To recover and recover alkali metals from water containing various solutes that are difficult to concentrate, separate, and recover by using multiple stages of nanofiltration membranes Can do.
1:原水
2:原水タンク
3:前処理ユニット
4:原水供給ポンプ
5:昇圧ポンプ
6:1段目ナノ濾過膜ユニット
7:2段目ナノ濾過膜ユニット
8:最終濃縮水
9:回収ユニット
10:回収アルカリ金属
11:低濃度水(排水)
12:ブースターポンプ
13:昇圧ポンプ
14,14’:濃縮ユニット
15:透過水
16:廃アルカリ土類金属
17:アルカリ土類金属除去ユニット
18:アルカリ土類金属除去水(回収水)
19:酸
20:希釈水
21:加熱ユニット
1: Raw water 2: Raw water tank 3: Pretreatment unit 4: Raw water supply pump 5: Booster pump 6: First stage nanofiltration membrane unit 7: Second stage nanofiltration membrane unit 8: Final concentrated water 9: Recovery unit 10: Recovery alkali metal 11: Low-concentration water (drainage)
12: Booster pump 13: Booster pump 14, 14 ': Concentration unit 15: Permeated water 16: Waste alkaline earth metal 17: Alkaline earth metal removal unit 18: Alkaline earth metal removal water (recovered water)
19: Acid 20: Dilution water 21: Heating unit

Claims (15)

  1.  ナノ濾過膜を用いてアルカリ金属を含有する原水からアルカリ金属を含む透過水を分離すること、及び前記透過水に含まれる前記アルカリ金属を後処理で回収すること、を含むアルカリ金属分離回収方法において、ナノ濾過膜ユニットを少なくとも2段に構成し、後段のナノ濾過膜ユニットの供給水として前段のナノ濾過膜ユニットの濃縮水を用いることを特徴とするアルカリ金属分離回収方法。 In an alkali metal separation and recovery method, comprising: separating permeated water containing alkali metal from raw water containing alkali metal using a nanofiltration membrane; and recovering the alkali metal contained in the permeated water by post-treatment. An alkali metal separation / recovery method, wherein the nanofiltration membrane unit is constituted in at least two stages, and the concentrated water of the preceding nanofiltration membrane unit is used as the supply water for the latter nanofiltration membrane unit.
  2.  前記ナノ濾過膜ユニットにおいて、第1段のナノ濾過膜ユニットと最終段のナノ濾過膜ユニットが異なることを特徴とする請求項1に記載のアルカリ金属分離回収方法。 The alkali metal separation and recovery method according to claim 1, wherein in the nanofiltration membrane unit, the first-stage nanofiltration membrane unit and the final-stage nanofiltration membrane unit are different.
  3.  前記第1段のナノ濾過膜ユニットの純水透水性能が、前記最終段のナノ濾過膜ユニットの純水透水性能よりも小さいことを特徴とする請求項2に記載のアルカリ金属分離回収方法。 3. The alkali metal separation and recovery method according to claim 2, wherein the pure water permeability of the first stage nanofiltration membrane unit is smaller than the pure water permeability of the final stage nanofiltration membrane unit.
  4.  前記第1段のナノ濾過膜ユニットにおけるアルカリ金属透過率に対する硫酸イオン透過率の比が、前記最終段のナノ濾過膜ユニットにおけるアルカリ金属透過率に対する硫酸イオン透過率の比よりも小さいことを特徴とする請求項2または3に記載のアルカリ金属分離回収方法。 The ratio of the sulfate ion permeability to the alkali metal permeability in the first-stage nanofiltration membrane unit is smaller than the ratio of the sulfate ion permeability to the alkali metal permeability in the final-stage nanofiltration membrane unit. The method for separating and recovering alkali metal according to claim 2 or 3.
  5.  前記第1段のナノ濾過膜ユニット内のナノ濾過膜が脂肪族系ポリアミドを主成分として含み、前記最終段のナノ濾過膜ユニット内のナノ濾過膜が芳香族系ポリアミドを主成分として含むことを特徴とする請求項2~4のいずれか一項に記載のアルカリ金属分離回収方法。 The nanofiltration membrane in the first-stage nanofiltration membrane unit includes an aliphatic polyamide as a main component, and the nanofiltration membrane in the final-stage nanofiltration membrane unit includes an aromatic polyamide as a main component. The method for separating and recovering alkali metal according to any one of claims 2 to 4, wherein
  6.  少なくとも2段に構成されたナノ濾過膜ユニットがすべて同じナノ濾過膜ユニットであるとともに、少なくとも1つのナノ濾過膜ユニットの濃縮水を昇圧することを特徴とする請求項1に記載のアルカリ金属分離回収方法。 2. The alkali metal separation and recovery according to claim 1, wherein all of the nanofiltration membrane units configured in at least two stages are the same nanofiltration membrane unit, and the concentrated water of at least one nanofiltration membrane unit is pressurized. Method.
  7.  少なくとも1つのナノ濾過膜ユニットの透過水を濃縮する透過水濃縮工程をさらに含み、その工程後アルカリ金属を後処理で回収することを特徴とする請求項1~6のいずれか一項に記載のアルカリ金属分離回収方法。 The permeated water concentration step of concentrating the permeate of at least one nanofiltration membrane unit is further included, and the alkali metal is recovered by post-treatment after that step. Alkali metal separation and recovery method.
  8.  前記透過水濃縮工程が蒸発法、膜蒸留法、アルカリ金属除去率95%以上の逆浸透膜を用いる方法のいずれかであることを特徴とする請求項7に記載のアルカリ金属分離回収方法。 The alkali metal separation and recovery method according to claim 7, wherein the permeate concentration step is any one of an evaporation method, a membrane distillation method, and a method using a reverse osmosis membrane having an alkali metal removal rate of 95% or more.
  9.  少なくとも最終段のナノ濾過膜ユニットの透過水を透過水濃縮工程に供した後、精製阻害物質を除去してから後処理でアルカリ金属を回収することを特徴とする請求項7または8に記載のアルカリ金属分離回収方法。 The alkali metal is recovered by post-treatment after removing the purification inhibitor after at least the permeated water of the nanofiltration membrane unit in the final stage is subjected to the permeated water concentration step. Alkali metal separation and recovery method.
  10.  少なくとも1つのナノ濾過膜ユニットの供給水に酸を添加することを特徴とする請求項1~9のいずれか一項に記載のアルカリ金属分離回収方法。 The method for separating and recovering alkali metal according to any one of claims 1 to 9, wherein an acid is added to water supplied to at least one nanofiltration membrane unit.
  11.  最終段のナノ濾過膜ユニットの濃縮水に含有される精製阻害物質を除去処理し、その処理水をいずれかのナノ濾過膜ユニットの供給水ラインに還流することを特徴とする請求項1~10のいずれか一項に記載のアルカリ金属分離回収方法。 The purification inhibitory substance contained in the concentrated water of the final nanofiltration membrane unit is removed, and the treated water is returned to the supply water line of any of the nanofiltration membrane units. The alkali metal separation and recovery method according to any one of the above.
  12.  少なくとも1つのナノ濾過膜ユニットの供給水に希釈水を混合することを特徴とする請求項1~11のいずれか一項に記載のアルカリ金属分離回収方法。 The method for separating and recovering alkali metal according to any one of claims 1 to 11, wherein dilution water is mixed with water supplied to at least one nanofiltration membrane unit.
  13.  前記希釈水が、前記透過水濃縮工程において産生される淡水であることを特徴とする請求項12に記載のアルカリ金属分離回収方法。 13. The alkali metal separation and recovery method according to claim 12, wherein the dilution water is fresh water produced in the permeate concentration step.
  14.  少なくとも1つのナノ濾過膜ユニットの供給水を加温することを特徴とする請求項1~13のいずれか一項に記載のアルカリ金属分離回収方法。 The method for separating and recovering alkali metal according to any one of claims 1 to 13, wherein water supplied to at least one nanofiltration membrane unit is heated.
  15.  ナノ濾過膜を用いてアルカリ金属を含有する原水からアルカリ金属を含む透過水を分離し、前記透過水に含まれる前記アルカリ金属を後処理で回収するためのアルカリ金属分離回収装置であって、該装置が少なくとも2段のナノ濾過膜ユニットを含み、前段のナノ濾過膜ユニットの濃縮水ラインが後段のナノ濾過膜ユニットの供給水ラインに連結されていることを特徴とするアルカリ金属分離回収装置。 An alkali metal separation and recovery device for separating permeated water containing alkali metal from raw water containing alkali metal using a nanofiltration membrane, and recovering the alkali metal contained in the permeated water by post-treatment, The apparatus includes at least two nanofiltration membrane units, and the concentrated water line of the preceding nanofiltration membrane unit is connected to the supply water line of the latter nanofiltration membrane unit.
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