WO2020059455A1 - Procédé permettant la récupération de calcium à partir de laitier d'affinage d'acier - Google Patents

Procédé permettant la récupération de calcium à partir de laitier d'affinage d'acier Download PDF

Info

Publication number
WO2020059455A1
WO2020059455A1 PCT/JP2019/033881 JP2019033881W WO2020059455A1 WO 2020059455 A1 WO2020059455 A1 WO 2020059455A1 JP 2019033881 W JP2019033881 W JP 2019033881W WO 2020059455 A1 WO2020059455 A1 WO 2020059455A1
Authority
WO
WIPO (PCT)
Prior art keywords
calcium
aqueous solution
steelmaking slag
slag
carbon dioxide
Prior art date
Application number
PCT/JP2019/033881
Other languages
English (en)
Japanese (ja)
Inventor
康 福居
宏毅 川並
Original Assignee
日鉄日新製鋼株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 日鉄日新製鋼株式会社 filed Critical 日鉄日新製鋼株式会社
Publication of WO2020059455A1 publication Critical patent/WO2020059455A1/fr

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
    • B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
    • B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B5/00—Treatment of  metallurgical  slag ; Artificial stone from molten  metallurgical  slag 
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/02—Dephosphorising or desulfurising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the present invention relates to a method for recovering calcium from steelmaking slag.
  • Steelmaking slag (such as converter slag, pretreatment slag, secondary refining slag, and electric furnace slag) generated in the steelmaking process is used in a wide range of applications including cement materials, roadbed materials, civil engineering materials, and fertilizers (non-patented). References 1-3). In addition, some steelmaking slag not used for the above applications is landfilled.
  • Steelmaking slag includes calcium (Ca), iron (Fe), silicon (Si), manganese (Mn), magnesium (Mg), aluminum (Al), phosphorus (P), titanium (Ti), chromium (Cr), It is known that elements such as sulfur (S) are contained.
  • the element most contained in the steelmaking slag is calcium used in a large amount in the steelmaking process, and usually contains Fe second most.
  • about 20% to 50% by mass of the total mass of the steelmaking slag is calcium, and about 1% to 30% by mass is Fe.
  • Calcium in the steelmaking slag is formed by free lime (CaO) supplied in the steelmaking process remaining as it is, or free lime precipitated during the solidification of the steelmaking slag, and free lime reacting with water vapor or carbon dioxide in the air to form hydroxide.
  • Calcium carbonate and calcium oxide are the main slag forming materials in the iron making process and the steel making process during the iron making process, and are used as modifiers for the basicity and viscosity of the slag, as dephosphorizers from molten steel, and the like. I have. Further, calcium hydroxide obtained by adding water to calcium oxide is used as a neutralizing agent such as an acid in a drainage process. Therefore, it is expected that if the calcium compound contained in the steelmaking slag is recovered and reused in the ironmaking process, the cost of ironmaking can be reduced.
  • Calcium in steelmaking slag can be recovered by eluting it in an acidic aqueous solution such as hydrochloric acid, nitric acid or sulfuric acid.
  • an acidic aqueous solution such as hydrochloric acid, nitric acid or sulfuric acid.
  • the salt of calcium and the above-mentioned acid produced in this method is difficult to reuse.
  • calcium chloride generated by eluting calcium in steelmaking slag with hydrochloric acid can be reused by heating to form an oxide, but there is a problem that the processing cost of harmful chlorine gas generated during the heating is high.
  • calcium in the steelmaking slag is eluted and recovered in an acidic aqueous solution, there is a problem that the cost of purchasing the acid and disposing of the acid after the elution treatment is high.
  • Patent Document 1 describes a method in which carbon dioxide is blown into an aqueous solution in which calcium in a converter slag is eluted to recover precipitated calcium carbonate. At this time, the lower limit of the pH is maintained at about 10 in order to suppress the generation of calcium hydrogen carbonate having high solubility in water. Patent Literature 1 does not describe a specific method for maintaining the pH at 10 or more, but it is thought that the pH is maintained at 10 or more by adjusting the amount of carbon dioxide blown.
  • Patent Document 2 discloses that a crushed steelmaking slag is separated into an iron-enriched phase and a phosphorus-enriched phase, and a calcium compound in the phosphorus-enriched phase is dissolved in washing water in which carbon dioxide is dissolved. A method is described in which calcium bicarbonate in washing water is precipitated as calcium carbonate by heating to about ° C. and recovered.
  • Patent Document 3 describes a method for eluting and recovering a calcium compound from steelmaking slag in a plurality of times.
  • this method it is described that by immersing steelmaking slag (pretreatment slag) in water into which carbon dioxide has been blown a plurality of times, a 2CaO.SiO2 phase and phosphorus dissolved in this phase are preferentially eluted. .
  • Patent Literature 4 discloses a method of contacting steelmaking slag with an aqueous solution of CO 2 to elute calcium and phosphorus, and then removing carbon dioxide from the aqueous solution to precipitate a calcium compound and a phosphorus compound, thereby recovering calcium.
  • Patent Literature 4 describes that the method can elute a larger amount of calcium more easily than the methods described in Patent Literatures 1 to 3 and increase calcium recovery efficiency.
  • Patent Document 4 discloses a method for removing carbon dioxide from an aqueous solution in which calcium and phosphorus are eluted, by adding one or more gases selected from the group consisting of air, nitrogen, oxygen, hydrogen, argon, and helium into the aqueous solution. Is described.
  • Fe in the steelmaking slag exists as iron-based oxides, calcium iron aluminum oxide, and, to a lesser extent, metallic iron.
  • the iron-based oxide contains Mn or Mg and also contains a small amount of elements such as Ca, Al, Si, P, Ti, Cr and S.
  • Calcium iron aluminum oxide also contains a small amount of elements such as Si, P, Ti, Cr and S.
  • iron-based oxides also include compounds in which a part of the surface has been changed to hydroxides or the like by water vapor in the air, and calcium iron aluminum oxide also includes water vapor in the air and carbon dioxide. And a compound in which a part of the surface has been changed to a hydroxide or a carbonate.
  • iron-based oxides exist as wustite-based oxides (FeO), and also exist as hematite-based oxides (Fe 2 O 3 ) and magnetite-based oxides (Fe 3 O 4 ).
  • the wustite-based oxide and the hematite-based oxide can be separated from the steelmaking slag by magnetic separation because the magnetite-based oxide (Fe 3 O 4 ), which is a ferromagnetic material, is dispersed therein.
  • a magnetite-based oxide alone or coexisting with another iron-based oxide can also be separated from steelmaking slag by magnetic separation.
  • Patent Documents 5 to 7 disclose a method of modifying a wustite-based oxide into a magnetite-based oxide by an oxidation treatment or the like in order to separate more iron-based oxides by magnetic separation.
  • the calcium iron aluminum oxide is magnetized to become a magnetic material, it can be separated from steelmaking slag by magnetic separation.
  • Iron-based oxides and calcium iron aluminum oxide (hereinafter collectively referred to as “iron-based compounds.
  • Calcium iron aluminum oxide is both a calcium compound and an iron-based compound.) Since it is as small as 0.1% by mass or less, it can be used as a raw material for a blast furnace or sintering if it is separated and recovered from steelmaking slag by the above-described magnetic separation or the like.
  • Metallic iron is Fe that has been caught in the slag in the steelmaking process and minute Fe that precipitates during the solidification of the steelmaking slag. Larger pieces of metallic iron are removed by magnetic separation or other methods during a dry process of crushing or grinding steelmaking slag in the atmosphere.
  • the present invention can be precipitated calcium eluted into CO 2 solution from steelmaking slag in a more simple method, to provide a method for recovering calcium from steel slag, and an object .
  • the present invention includes a step of contacting the CO 2 steelmaking in an aqueous solution slag is an aqueous solution containing carbon dioxide, and a step of spraying the CO 2 aqueous solution the steelmaking slag in contact, steelmaking slag For recovering calcium from lime.
  • FIG. 1 is a flowchart of a method for recovering calcium from steelmaking slag according to the first embodiment of the present invention.
  • FIG. 2 is a schematic diagram showing a configuration of an apparatus for eluting calcium that can be used in the first embodiment of the present invention.
  • FIG. 3 is a schematic diagram illustrating a configuration of an apparatus that sprays a CO 2 aqueous solution in a closed container that can be used in the first embodiment of the present invention.
  • FIG. 4 is a schematic diagram showing another configuration of a device for spraying a CO 2 aqueous solution in a closed container that can be used in the first embodiment of the present invention.
  • FIG. 5 is a flowchart of a method for recovering calcium from steelmaking slag in the second embodiment of the present invention.
  • FIG. 1 is a flowchart of a method for recovering calcium from steelmaking slag according to the first embodiment of the present invention.
  • FIG. 2 is a schematic diagram showing a configuration of an apparatus for eluting calcium that
  • FIG. 6 is a schematic diagram showing a configuration of an apparatus which can be used in the second embodiment of the present invention and which can be used for spraying an aqueous solution of CO 2 in a closed container and charging it into a calcium-based alkaline substance.
  • FIG. 7 shows the concentration [H 2 CO 3 * ] of carbon dioxide (CO 2 ) and carbonic acid (H 2 CO 3 ), the concentration [HCO 3 ⁇ ] of hydrogen carbonate ion (HCO 3 ⁇ ), and the carbonate ion in the aqueous solution.
  • 5 is a graph showing the relationship between the concentration of (CO 3 2- ) [CO 3 2- ] and the pH.
  • FIG. 8 is a flowchart of a method for recovering calcium from steelmaking slag in the third embodiment of the present invention.
  • FIG. 9 is a flowchart of a method for recovering calcium from steelmaking slag according to a fourth embodiment of the present invention.
  • FIG. 1 is a flowchart of a method for recovering calcium from steelmaking slag according to the first embodiment of the present invention.
  • steelmaking slag is prepared (step S110), and the prepared steelmaking slag is brought into contact with an aqueous solution containing carbon dioxide (hereinafter, also simply referred to as “CO 2 aqueous solution”) (step S120).
  • CO 2 aqueous solution an aqueous solution containing carbon dioxide
  • step S130 There was sprayed with the CO 2 solution in contact (step S130), then, recovering the solid component comprising calcium deposited (step S140).
  • Step S110 Preparation of steelmaking slag
  • steelmaking slag is prepared.
  • the steelmaking slag is not particularly limited as long as it is slag discharged in the steelmaking process.
  • steelmaking slag include converter slag, pretreatment slag, secondary refining slag, and electric furnace slag.
  • the size of the structure such as calcium silicate, free lime and iron-based compounds contained in the steelmaking slag is about 1000 ⁇ m or less. Therefore, it is preferable that the steelmaking slag is crushed or pulverized (hereinafter, also simply referred to as “pulverization or the like”) after being discharged in the steelmaking process to be formed into particulate slag particles.
  • the maximum particle size of the crushed or pulverized slag particles is preferably about the same as or less than the structure of calcium silicate, free lime, iron-based compounds, and the like, and more preferably 1000 ⁇ m or less.
  • the maximum particle size is 1000 ⁇ m or less, the surface area per volume of the slag particles becomes larger, so that the CO 2 aqueous solution can sufficiently penetrate into the inside of the slag particles, or calcium silicate and free lime are used alone. Since calcium can be present as particles, calcium is easily eluted in the steps described below.
  • the maximum particle size of the slag particles is preferably 500 ⁇ m or less, more preferably 250 ⁇ m or less, and even more preferably 100 ⁇ m or less.
  • the slag particles can be reduced to such an extent that the maximum particle size falls within the above range, for example, by further crushing the crushed slag particles with a crusher including a hammer mill, a roller mill, a ball mill and the like.
  • the steelmaking slag is obtained by putting steelmaking slag in a container filled with water, leaching free lime and calcium hydroxide, and leaching calcium in the surface layer of a calcium compound, and then filtering the slag. It may be slag. Since the slag from which calcium has been eluted to some extent can be used by using the filtration residual slag, the load when eluting calcium by contact with the CO 2 aqueous solution can be reduced. At this time, the filtered water from which calcium is leached is a highly alkaline aqueous solution having a pH of 11 or more (hereinafter, also simply referred to as “highly alkaline leached water”). The highly alkaline leachate can be used as a calcium-based alkaline substance for further increasing the pH of the aqueous CO 2 solution in the second embodiment.
  • Step S120 Contact with CO 2 aqueous solution
  • the steelmaking slag is brought into contact with a CO 2 aqueous solution.
  • the steel slag elutes calcium by contact with CO 2 solution.
  • the steelmaking slag may be immersed in water in which carbon dioxide is dissolved in advance, or the carbon dioxide may be dissolved in water after immersing the steelmaking slag in water.
  • the carbon dioxide may be dissolved in water after immersing the steelmaking slag in water.
  • calcium elutes into the CO 2 aqueous solution calcium and carbon dioxide react with each other to produce water-soluble calcium bicarbonate. Therefore, the amount of carbon dioxide in the CO 2 aqueous solution decreases with the dissolution of calcium. Therefore, from the viewpoint of improving the calcium elution efficiency, it is preferable to introduce carbon dioxide into the CO 2 aqueous solution in contact with the steelmaking slag to continuously elute calcium. Note that, while the steelmaking slag is immersed in the aqueous solution, it is preferable to stir the slag from the viewpoint of increasing the reactivity.
  • Carbon dioxide can be dissolved in water, for example, by bubbling (blowing) a gas containing carbon dioxide. From the viewpoint of improving the dissolution of calcium from steelmaking slag, it is preferable that 30 ppm or more of non-ionized carbon dioxide (free carbonic acid) is dissolved in the aqueous solution. In addition, the amount of free carbonic acid that can be contained in general tap water is 3 mg / L or more and 20 mg / L or less.
  • the gas containing carbon dioxide may be pure carbon dioxide gas or a gas containing components other than carbon dioxide (for example, oxygen or nitrogen).
  • the gas containing carbon dioxide include exhaust gas after combustion, and a mixed gas of carbon dioxide, air, and water vapor. From the viewpoint of increasing the concentration of carbon dioxide in the aqueous solution to enhance the dissolution of calcium compounds (such as calcium silicate) from the steelmaking slag into the aqueous solution, the gas containing carbon dioxide has a high concentration of carbon dioxide (for example, 90%).
  • the steelmaking slag that is in contact with the CO 2 aqueous solution may be pulverized.
  • the steelmaking slag in contact with the CO 2 aqueous solution by grinding or the like a new silicon hardly dissolved in CO 2 aqueous solution, a hydroxide such as aluminum and iron, carbonates or hydrates yet to remain or deposit Surface is continuously formed.
  • a hydroxide such as aluminum and iron, carbonates or hydrates yet to remain or deposit Surface
  • the retrieved slag particles You may selectively grind etc. Since the extracted slurry has a small proportion of water, the slag particles to be pulverized or the like are more easily pulverized or the like.
  • the efficiency of the pulverization of the steelmaking slag and the like can be increased, and a larger amount of calcium can be easily eluted from the steelmaking slag.
  • FIG. 2 is a schematic diagram showing a configuration of an apparatus for eluting calcium (hereinafter, also simply referred to as “elution apparatus”) that can be used in the present embodiment.
  • the dissolution apparatus 100 contains a slurry containing a steelmaking slag and an aqueous solution of CO 2, and dissolves the steelmaking slag (hatched area in the figure) in the slurry, and removes the steelmaking slag from the bottom side of the dissolution and sedimentation tank 110.
  • a crushing unit 120 for crushing steelmaking slag contained in the obtained slurry a carbon dioxide introduction unit 130 for introducing carbon dioxide into the slurry, and a slurry taken out from the elution / sedimentation tank 110 to the crushing unit 120, and And a slurry flow path 140 for re-introducing the slurry containing the steelmaking slag pulverized in the pulverizing section 120 into the elution / sedimentation tank 110.
  • the elution / sedimentation tank 110 is a container for storing the slurry.
  • the elution / sedimentation tank 110 has a slurry outlet 112 on the bottom side, and a slurry re-introduction port 114 for re-introducing the slurry from the pulverizing section 120 on the upper side (liquid level side) of the slurry outlet 112.
  • the bottom surface of the elution / settling tank 110 is an inclined surface that is inclined so as to become deeper toward the slurry outlet 112 in order to easily take out the deposited steelmaking slag.
  • the elution / sedimentation tank 110 has an impeller 118 that stirs the slurry near the bottom surface in order to easily take out the steelmaking slag deposited on the bottom surface.
  • the impeller 118 is rotated by a rotating rod 119 disposed through the slurry flow path 142 so that even when the dissolution / settling tank 110 is enlarged, the steelmaking slag deposited on the bottom surface can be easily removed by these operations.
  • the sedimentation tank 110 be rotated while being supported from the bottom side.
  • the impeller 118 is disposed only on the bottom surface of the elution / settling tank 110 so as not to prevent the steelmaking slag from settling on the upper side.
  • the pulverizing section 120 is connected to the slurry outlet 112 of the elution / settling tank 110 by a slurry flow path 142, and is connected to the slurry re-introduction port 114 of the elution / settling tank 110 by a slurry flow path 144.
  • the crushing unit 120 crushes steelmaking slag contained in the slurry introduced from the slurry flow path 142.
  • the pulverizing section 120 causes a known ball used in a ball mill and a known bead used in a bead mill (hereinafter, also simply referred to as a “pulverizing medium”), which are put into a pulverizing container, to flow by stirring, and to flow and rotate.
  • the slag particles are smashed by the slag particles sliding on the slag particles when the crushing medium comes into contact with the slag particles.
  • the crushing unit 120 may be a continuous crushing device that crushes steelmaking slag included in the slurry while flowing the slurry, or may temporarily store the slurry and crush the steelmaking slag included in the slurry. Or a batch-type pulverizer.
  • the carbon dioxide introduction unit 130 introduces carbon dioxide supplied from an external carbon dioxide supply source into the slurry.
  • the carbon dioxide introduction unit 130 may introduce carbon dioxide into the slurry in any of the elution / sedimentation tank 110, the slurry channel 142 (see FIG. 2), the pulverizing unit 120, and the slurry channel 144.
  • the carbon dioxide introduction unit 130 may have a bubble miniaturization device for miniaturizing carbon dioxide bubbles.
  • the slurry flow path 140 takes out the slurry in which the concentration of the steelmaking slag is increased by the sedimentation of the steelmaking slag from the slurry outlet 112 of the elution / sedimentation tank 110, and introduces the slurry into the pulverizing section 120. It has a slurry flow path 144 for re-introducing a slurry containing steelmaking slag pulverized at 120 into the elution / sedimentation tank 110 and a pump 146 for flowing the slurry.
  • Elution-sedimentation tank 110 or a slurry containing steelmaking slag and CO 2 solution is introduced, or steel slag and CO 2 aqueous solution is separately introduced to a slurry.
  • the steelmaking slag in the slurry settles from slag particles having a larger particle size.
  • the slurry containing the settled steelmaking slag is stirred by the impeller 118 to increase the fluidity, taken out from the slurry outlet 112, and introduced into the pulverizing unit 120 through the slurry flow path 142 by the pump 146.
  • the slurry containing the steelmaking slag pulverized in the pulverizing section 120 is re-introduced into the elution / sedimentation tank 110 from the slurry channel 144.
  • carbon dioxide is continuously introduced into the slurry from the carbon dioxide introduction unit 130.
  • Step S130 Spray of CO 2 aqueous solution
  • the CO 2 aqueous solution that has come into contact with the steelmaking slag is sprayed.
  • the calcium precipitated in this step is not limited to calcium carbonate, and calcium carbonate hydrate, basic calcium carbonate, calcium hydroxide, and the like may be precipitated.
  • Spraying may be performed in the form of a shower or in the form of a mist.
  • the spray is performed by spraying the droplets of the CO 2 aqueous solution. Is preferably performed so that the diameter is 5000 ⁇ m or less, more preferably performed so that the diameter is 1000 ⁇ m or less, further preferably performed so that the diameter is 500 ⁇ m or less, and the diameter is 200 ⁇ m or less. It is particularly preferred that the process be performed as follows.
  • the lower limit of the diameter is not particularly limited, but may be 0.1 ⁇ m.
  • the diameter of the droplet can be adjusted according to the size of a discharge port or a nozzle for spraying the CO 2 aqueous solution.
  • Spraying may be performed multiple times from the viewpoint of further promoting the precipitation of calcium by removing carbon dioxide. On the other hand, if a sufficient amount of calcium is deposited, spraying may be performed only once. The number of times of spraying can be determined based on the pH of the CO 2 aqueous solution after spraying (described later) and the like.
  • spraying is performed in a space having an atmosphere gas having a partial pressure of carbon dioxide lower than the equilibrium pressure of carbon dioxide in the aqueous CO 2 solution in contact with the steelmaking slag. It is preferable to perform it.
  • the atmosphere gas is not particularly limited, but is preferably a gas that has lower reactivity with or does not react with a CO 2 aqueous solution than gases (chlorine gas and sulfur dioxide gas) that react with water to generate ions.
  • gases chlorine gas and sulfur dioxide gas
  • the generated ions react with calcium ions in the CO 2 aqueous solution to form a salt, and when the precipitation efficiency of calcium decreases or when it is difficult to remove the salt, Reuse of the aqueous solution of CO 2 after the precipitation of calcium may be troublesome.
  • the atmosphere gas is a gas that has low reactivity or does not react with the CO 2 aqueous solution, and in particular, is a gas that does not generate ions that form salts with calcium ions by contact with the CO 2 aqueous solution. Is preferred.
  • the gas having low or no reactivity with the CO 2 aqueous solution may be an inorganic gas or an organic gas.
  • inorganic gases are preferred because they are less likely to burn and explode when leaked to the outside.
  • the inorganic gas include air, a gas containing nitrogen (N 2 ), oxygen (O 2 ), hydrogen (H 2 ), argon (Ar), helium (He), and the like, and a mixed gas thereof. Is more preferable.
  • the atmosphere may be an atmosphere containing nitrogen (N 2 ) and oxygen (O 2 ) at a ratio of about 4: 1 and in an environment where spraying is performed.
  • organic gas examples include methane (CH 4 ), ethane (C 2 H 6 ), ethylene (C 2 H 4 ), acetylene (C 2 H 2 ), propane (C 3 H 8 ), and fluorocarbon gas. (C n H m F 2n + 2-m ) and the like.
  • the spraying is preferably performed in a closed container from the viewpoint of recovering the carbon dioxide removed from the aqueous CO 2 solution in this step and making it easier to reuse.
  • the recovered carbon dioxide for example, can be used to introduce the CO 2 aqueous solution (step S120) when contacting the steel slag in CO 2 solution.
  • the carbon dioxide concentration in the sealed container with carbon dioxide removed from the CO 2 aqueous solution increases, or the rate of removal of carbon dioxide from the CO 2 aqueous solution is reduced, or removed And the calcium deposition efficiency may decrease. Therefore, it is preferable to spray the CO 2 aqueous solution while introducing the above atmospheric gas into the closed container and discharging the gas containing carbon dioxide from the closed container.
  • the solubility of carbon dioxide in water may be reduced by reducing or heating the inside of the sealed container.
  • the removal efficiency of carbon dioxide from the CO 2 aqueous solution can be increased, and the precipitation efficiency of calcium can also be increased.
  • the solubility of calcium carbonate or the like in water is reduced, so that the calcium deposition efficiency can be increased.
  • the pressure inside the sealed container is preferably equal to or lower than the atmospheric pressure (about 0.1 MPa), and the temperature inside the sealed container at this time is such that the vapor pressure of water does not exceed the atmospheric pressure.
  • the temperature is more preferably room temperature or higher and lower than 100 ° C. (when the inside of the closed container is at atmospheric pressure). Either one of the pressure reduction and the heating may be performed, or both may be performed.
  • FIG. 3 is a schematic diagram illustrating a configuration of a device (hereinafter, also simply referred to as “spray device”) for spraying a CO 2 aqueous solution in a closed container that can be used in the present embodiment.
  • a device hereinafter, also simply referred to as “spray device” for spraying a CO 2 aqueous solution in a closed container that can be used in the present embodiment.
  • Spraying device 200 includes a sealed container 210 that CO 2 aqueous solution is sprayed, the spray device 220 to spray the CO 2 aqueous solution, a gas inlet 230 for introducing the atmospheric gas inside the sealed container 210, from the interior of the sealed container 210 It has a gas discharge part 240 for discharging gas containing carbon dioxide, a pump 250 for reducing the pressure inside the sealed container, and a heater 260 for heating the inside of the sealed container.
  • the closed container 210 is a container into which the CO 2 aqueous solution that has come into contact with the steelmaking slag is sprayed.
  • the closed container 210 has a CO 2 aqueous solution outlet 212 for taking out the sprayed CO 2 aqueous solution on the bottom side.
  • the bottom surface of the sealed container 210 is an inclined surface that is inclined so as to become deeper toward the CO 2 aqueous solution outlet 212 in order to easily take out the CO 2 aqueous solution that has reached the bottom surface after being sprayed.
  • Nebulizer 220 before the CO 2 solution passage 222 CO 2 aqueous solution in contact with the steelmaking slag in step (step S120) is Nagareoku, the CO 2 aqueous solution is Nagareoku from CO 2 aqueous solution passage 222 like a shower shower head 224 for spraying.
  • the shower head 224 is installed on the upper side of the closed container 210, and discharges a droplet of the CO 2 aqueous solution from a plurality of openings toward the bottom side of the closed container 210.
  • the sprayer 220 has only one shower head 224, but the sprayer 220 may have a plurality of shower heads.
  • the sprayed CO 2 aqueous solution is stored on the bottom surface side of the closed container 210 having an inclined surface, but the CO 2 aqueous solution is not stored, and the sprayed CO 2 aqueous solution is used as it is.
  • the second aqueous solution outlet 212 may be discharged.
  • the gas introduction unit 230 introduces the above atmospheric gas into the closed container 210.
  • the bottom side of the container is removed carbon dioxide from the atomized CO 2 aqueous solution have reduced concentration of carbon dioxide in the CO 2 aqueous solution (the equilibrium pressure of carbon dioxide), carbon dioxide from the CO 2 aq It is difficult to remove. Therefore, it is preferable that the gas introduction unit 230 introduces the above-mentioned atmosphere gas from the bottom side of the closed vessel 210 to lower the concentration of carbon dioxide (partial pressure of carbon dioxide) in the atmosphere gas on the bottom side of the closed vessel 210. .
  • FIG. 3 only two gas introduction units 230 are provided for the closed container 210, but a plurality of gas introduction units 230 are arranged at equal intervals in the circumferential direction along the outer periphery of the closed container 210.
  • the above-mentioned atmospheric gas may be uniformly introduced to the bottom side inside the closed vessel 210, and the carbon dioxide concentration on the bottom side may be uniformly reduced as a whole.
  • the gas discharge unit 240 discharges the atmospheric gas from the inside of the closed container 210. Atmosphere gas discharged is because it contains carbon dioxide removed from the CO 2 aqueous solution by spraying the CO 2 aqueous solution, carbon dioxide concentration is high. According to the present embodiment, at this time, the atmospheric gas having a carbon dioxide concentration of 5% by volume or more can be discharged from the gas discharge unit 240. By continuously supplying a constant amount of the CO 2 aqueous solution, the concentration and the amount of carbon dioxide in the discharged atmospheric gas can be kept constant from the beginning to the end of spraying. From such an atmospheric gas, it is easy to obtain industrially reusable carbon dioxide having a carbon dioxide concentration of 99% by volume or more by industrially recovering and purifying carbon dioxide. is there. Thus, in the present embodiment, an atmosphere gas having a high carbon dioxide concentration can be obtained, and the carbon dioxide can be easily reused.
  • the pump 250 is disposed in the pipe of the gas discharge unit 240, and adjusts the discharge amount of the atmospheric gas from the inside of the closed container 210 to reduce the pressure inside the closed container 210.
  • the pump 250 increases the efficiency of removing carbon dioxide from the CO 2 aqueous solution sprayed by the above-described depressurization, and also reduces the pressure from the gas discharge unit 240 disposed on the upper side of the closed vessel 210 to thereby reduce the lower side of the closed vessel 210. And promotes the movement of carbon dioxide from above to the upper side, so that the concentration of carbon dioxide inside the closed container 210 is easily reduced.
  • the heater 260 may be a known heater such as a jacket heater for heating the inside of the closed container 210.
  • a known heater such as a jacket heater for heating the inside of the closed container 210.
  • the efficiency of removing carbon dioxide from the CO 2 aqueous solution can be increased.
  • the efficiency of calcium precipitation from the CO 2 aqueous solution can be increased.
  • the heating temperature for increasing the carbon dioxide removal efficiency and the calcium deposition efficiency is reduced. Even if not so high, the calcium deposition efficiency can be efficiently and sufficiently increased.
  • the heater 260 may heat the atmospheric gas introduced from the gas introduction unit 230.
  • FIG. 4 is a schematic diagram illustrating a configuration of another spraying device 200a according to the present embodiment.
  • Spray device 200a has a nozzle 226 spraying device 220a is sprayed CO 2 aqueous solution is atomized. Also in such a spraying device 200a, similarly, carbon dioxide can be efficiently removed from the CO 2 aqueous solution, and calcium can be efficiently precipitated.
  • the spray device 220a has only one nozzle 226, but the spray device 220a may have a plurality of nozzles.
  • the aqueous solution after the precipitation of calcium can simplify or eliminate wastewater treatment, and can suppress the cost of wastewater treatment.
  • the present embodiment can reduce the amount of wastewater generated by the treatment.
  • Step S140 Recover solid component
  • a solid component containing calcium precipitated by spraying the CO 2 aqueous solution is recovered.
  • the solid component can be recovered by a known method including a sedimentation precipitation method and pressure filtration.
  • This solid component includes calcium derived from steelmaking slag.
  • FIG. 5 is a flowchart of a method for recovering calcium from steelmaking slag in the second embodiment of the present invention.
  • step S110 to prepare the steelmaking slag (step S110), contacting the steel slag prepared for CO 2 aqueous solution (step S120), the CO 2 aqueous solution steelmaking slag in contact Is sprayed (step S130). Thereafter, in the present embodiment, a calcium-based alkaline substance is introduced into the CO 2 aqueous solution (Step S150), and a solid component containing precipitated calcium is recovered (Step S140).
  • Step S110, step S120, step S130, and step S140 can be performed in the same manner as in the first embodiment, and thus redundant description will be omitted.
  • FIG. 6 is a schematic diagram showing the structure of a spray apparatus that can be used for spraying of CO 2 solution in this embodiment (step S130) and turned into calcium-based CO 2 aqueous solution of an alkaline material (step S150).
  • Spray apparatus 200b has an alkaline substance inlet 270 to introduce an alkaline substance calcium system in the interior of the CO 2 aqueous solution of the sealed container 210a, the sealed container 210a is a CO 2 aqueous solution is charged with alkaline substance calcium-based It has a stirring blade 214 for stirring and a rotating rod 216 for rotating the stirring blade 214.
  • the other configuration of the spraying device 200b is the same as that of the spraying device 200 shown in FIG.
  • the alkaline substance introduction port 270 introduces a calcium-based alkaline substance into the inside of the closed container 210a and makes the calcium-based alkaline substance come into contact with the CO 2 aqueous solution.
  • the alkaline substance inlet 270 injects a calcium-based alkaline substance into the CO 2 aqueous solution that has been sprayed and collected at the bottom of the closed container 210a.
  • step S130 in the spraying of the CO 2 aqueous solution (step S130), the pH of the CO 2 aqueous solution is increased by removing carbon dioxide, and calcium is precipitated from the CO 2 aqueous solution.
  • the pH of the CO 2 aqueous solution exceeds about 8.5, carbon dioxide can no longer exist in the CO 2 aqueous solution, and therefore, the rise of the pH of the CO 2 aqueous solution by the above spraying is limited to about 8.5. It is.
  • hydrogen carbonate ions HCO 3 ⁇
  • Ca 2+ calcium ions
  • FIG. 7 shows the concentration of carbonic acid (H 2 CO 3 ) [H 2 CO 3 * ], the concentration of hydrogen carbonate ion (HCO 3 ⁇ ) [HCO 3 ⁇ ], and the concentration of carbonate ion (CO 2 ) in the aqueous solution.
  • H 2 CO 3 * is the combined concentration of the concentration of carbon dioxide [CO 2 ] and the concentration of carbon dioxide [H 2 CO 3 ].
  • the presence state of each of the above carbonic acid species (CO 2 , H 2 CO 3 , HCO 3 ⁇ , and CO 3 2 ⁇ ) in the aqueous solution is determined by the following equilibrium formula (formula 2) to equilibrium formula (formula 4) It is represented by Specifically, when the pH is lower than about 8.5, the equilibrium relationship represented by the equilibrium equation (Equation 2) and the equilibrium equation (Equation 3) holds, and when the pH is higher than about 8.5. Satisfies the equilibrium relationship represented by the equilibrium equation (Equation 3) and the equilibrium equation (Equation 4).
  • the pH of the aqueous solution can be increased only to about pH 8.5 at which carbon dioxide does not exist in the aqueous solution.
  • a calcium-based alkaline substance into the CO 2 aqueous solution after removing carbon dioxide to some extent, the calcium concentration and the pH in the CO 2 aqueous solution are increased, and the equilibrium of the equation (5) is shifted to the right. It can facilitate the precipitation of calcium carbonate.
  • the lower the carbon dioxide concentration of the aqueous CO 2 solution the lower the efficiency of further removing carbon dioxide from the aqueous CO 2 solution. Therefore, in order to raise the pH of the CO 2 aqueous solution by spraying (removal of carbon dioxide), it is necessary to exponentially increase the flight distance of the sprayed CO 2 aqueous solution.
  • the removal of carbon dioxide from the CO 2 aqueous solution by spraying is stopped when a certain amount of carbon dioxide remains in the CO 2 aqueous solution, and thereafter the precipitation of calcium is promoted by introducing a calcium-based alkaline substance. By doing so, it is possible to suppress the processing from becoming complicated due to an increase in the size of the spray device and an increase in the number of times of spraying.
  • pH of CO 2 aqueous solution is 6.5 to 8.0, preferably continued until the pH of the CO 2 aqueous solution is 6.6 to 7.5, after which the alkaline substance calcium-based CO 2 It is preferable to put in an aqueous solution.
  • the calcium-based alkaline substance may be an alkaline substance containing calcium (Ca). From the viewpoint of increasing the pH and increasing the amount of precipitated calcium, calcium hydroxide (Ca ( OH) 2 ) or a composition that generates calcium hydroxide when introduced into water (hereinafter, also simply referred to as “calcium hydroxide-based composition”).
  • the calcium hydroxide-based composition may be an aqueous solution in which calcium hydroxide is dissolved or a slurry in which solid calcium hydroxide is dispersed.
  • the substance containing calcium hydroxide may be solid calcium hydroxide.
  • the calcium-based alkaline substance may be solid calcium oxide (CaO), which changes into calcium hydroxide when injected into a CO 2 aqueous solution.
  • the aqueous solution in which calcium hydroxide is dissolved can be easily obtained in each step of the process of recovering calcium from steelmaking slag.
  • the aqueous solution in which the calcium hydroxide is dissolved may be high alkali leaching water obtained when obtaining filtration residual slag in the step of preparing steelmaking slag, or may be hydrated in a third embodiment described later.
  • the water may be hydration-treated water obtained after the treatment, or may be magnetic separation water obtained after wet magnetic separation in a fourth embodiment described later.
  • a liquid component obtained by contacting steelmaking slag with water such as the above-mentioned highly alkaline leaching water, hydration-treated water, and magnetic separation water, is also referred to as slag leaching water.
  • the slag leaching water was obtained in a previous processing step on steelmaking slag in which calcium is precipitated by spraying a CO 2 aqueous solution (step S130) and charging a calcium-based alkaline substance (step S150). May be obtained during the process of processing other steelmaking slag. It is preferable to add the slag leachate to the CO 2 aqueous solution in this step from the viewpoint of effective utilization of the slag leachate discharged in each step for recovering calcium from the steelmaking slag.
  • the aqueous solution in which the calcium hydroxide is dissolved may be a waste liquid obtained by a process other than the process of recovering calcium from steelmaking slag.
  • the waste liquid include a waste aqueous solution generated when acetylene is produced by reacting calcium carbide (calcium carbide) with water.
  • the waste aqueous solution is substantially composed of water and calcium hydroxide. Therefore, the use of the waste aqueous solution can reduce the amount of impurities mixed into the solid component containing precipitated calcium.
  • a sodium-based substance containing sodium hydroxide or the like and an ammonia-based substance containing ammonia or the like may be added to the CO 2 aqueous solution.
  • the solid components containing precipitated calcium obtained by introducing these components generate sodium and toxic ammonia gas which may shorten the life of the refractory contained in the sintering furnace and the blast furnace. May contain ammonia. Therefore, it is preferable to promote the precipitation of calcium by adding the calcium-based alkaline substance.
  • the alkaline substance inlet 270 directly injects the calcium-based alkaline substance into the CO 2 aqueous solution collected at the bottom of the sealed container 210a.
  • the method of adding the calcium-based alkaline substance is not limited to this.
  • a separately provided tank downstream of the sealed container 210a may be charged with an alkaline substance of the calcium-based on CO 2 aqueous solution, in the flow path for communicating the sealed container 210a and the tank, CO 2 aq
  • a mixer for charging and mixing the above-mentioned calcium-based alkaline substance may be arranged.
  • the closed vessel 210a has a stirring blade 214 for stirring a CO 2 aqueous solution into which a calcium-based alkaline substance is charged, and a rotating rod 216 for rotating the stirring blade 214.
  • FIG. 6 shows a spraying device having a sprayer for spraying a CO 2 aqueous solution in a shower form
  • a calcium-based alkaline substance is charged by using a spraying device having a sprayer for spraying a CO 2 aqueous solution in a mist state. May be similarly performed.
  • FIG. 8 is a flowchart of a method for recovering calcium from steelmaking slag in the third embodiment of the present invention.
  • a steelmaking slag is prepared (step S110), and then the steelmaking slag is subjected to a hydration treatment (step S160). Thereafter, the hydration process alms steel slag is brought into contact with CO 2 aqueous solution (step S120), steelmaking slag is sprayed the CO 2 solution in contact (step S130), recovering a solid component comprising a precipitated calcium (Step S140).
  • Step S110, step S120, step S130, and step S140 can be performed in the same manner as in the first embodiment, and thus redundant description will be omitted.
  • the hydration treatment may be performed by a method and under conditions in which the calcium compound contained in the steelmaking slag is sufficiently hydrated.
  • calcium in steelmaking slag includes free lime, calcium hydroxide (Ca (OH) 2 ), calcium carbonate (CaCO 3 ), calcium silicate (Ca 2 SiO 4 , Ca 3 SiO 5 ) and calcium oxide. It exists as a calcium compound such as iron aluminum (Ca 2 (Al 1-x Fe x ) 2 O 5 ).
  • calcium silicate hydrate and calcium hydroxide (Ca (OH) 2 ) are generated from calcium silicate by a reaction represented by the following (Formula 7),
  • a calcium oxide-based hydrate is formed from calcium iron aluminum oxide by a reaction represented by the following (formula 8) (hereinafter, calcium-containing compounds that can be formed by hydration treatment are collectively referred to as “calcium hydrate” Also called “things").
  • Calcium hydrate generated by the above reaction or the like is easily dissolved in a CO 2 aqueous solution. Therefore, by performing the hydration treatment, calcium derived from calcium silicate and calcium iron aluminum contained in the steelmaking slag can be more easily eluted.
  • steelmaking slag usually contains only less than about 10% by mass.
  • calcium silicate is usually contained in steelmaking slag at about 25% by mass to 70% by mass
  • calcium iron aluminum is usually contained in steelmaking slag at about 2% by mass to 30% by mass. Therefore, if calcium contained in calcium silicate and calcium iron aluminum is easily eluted with the CO 2 aqueous solution by the hydration treatment, the amount of calcium eluted from the steelmaking slag to the CO 2 aqueous solution can be increased, It is considered that calcium can be recovered from the slag in a shorter time.
  • the total volume of the compound generated by the hydration treatment is usually larger than the total volume of the compound before the reaction. Furthermore, during the hydration process, some of the free lime in the steelmaking slag elutes into the water for treatment. Therefore, when the hydration treatment is performed, cracks are generated inside the slag particles, and the slag particles are likely to collapse starting from the cracks. When the slag particles collapse in this way, the particle diameter of the slag particles decreases, the surface area per volume increases, and water or a CO 2 aqueous solution can sufficiently penetrate into the steelmaking slag. Many calcium compounds can be hydrated, and when the steelmaking slag is subsequently brought into contact with a CO 2 aqueous solution (step S120), a larger amount of calcium can be eluted.
  • the hydration treatment is preferably performed by a method and under conditions that allow calcium silicate or calcium iron aluminum oxide contained in the steelmaking slag to be hydrated.
  • hydration treatment examples include a treatment in which the steelmaking slag immersed in water and settled is settled (hereinafter, also simply referred to as “immersion stationary”), and the steelmaking slag immersed in water is stirred or crushed.
  • Treatment hereinafter, also simply referred to as “immersion stirring”
  • treatment of leaving a paste containing water and slag particles hereinafter, also simply referred to as “pasting and standing”
  • pasting and standing treatment of leaving a paste containing water and slag particles
  • wet standing A process of leaving the steelmaking slag in the container. According to these methods, the steelmaking slag and the water can be brought into sufficient contact.
  • hydration treatment only one of the above immersion stationary, immersion stirring, pasting stationary and wet stationary may be performed, or two or more of these may be performed in an arbitrary order.
  • the hydration treatment by immersion and stirring is preferred from the viewpoint of more sufficiently hydrating the interior of the slag particles to facilitate the elution of calcium.
  • Immersion stirring may be performed by stirring a steelmaking slag immersed in water inside a container having a stirring impeller, or by pulverizing the steelmaking slag while stirring it with a ball mill. From the viewpoint of hydrating more sufficiently to the inside of the slag particles to make calcium more easily eluted, it is preferable that the immersion stirring is performed by pulverizing the steelmaking slag while stirring.
  • the above-described reaction due to the hydration treatment occurs when the calcium compound contacts water near or inside the surface of the steelmaking slag.
  • the amount of contact with water is greater near the surface. Therefore, calcium hydrate is more easily generated near the surface of the steelmaking slag.
  • the components contained in the steelmaking slag is dissolved in water used for hydration, as in the case of dissolving the CO 2 solution described above, silicon, aluminum, iron and manganese or their hydroxides, carbonates and Hydrates may remain or precipitate on the surface of the steelmaking slag. When these remaining or precipitated substances inhibit the penetration of water into the steelmaking slag, calcium hydrate is less likely to be generated inside the steelmaking slag.
  • the surface area of the slag particles can be increased, and the contact area between the water and the slag particles can be further increased.
  • a new surface on which the above-mentioned substance still does not remain or precipitate is continuously formed, and water is continuously transferred from the surface formed continuously to the inside of the steelmaking slag.
  • Calcium hydrate can be more easily generated inside the steelmaking slag.
  • the surface of the steelmaking slag the remaining or precipitated substance is removed, the contact area between water and slag particles becomes larger, and water is more easily permeated into the steelmaking slag. can do.
  • the water used for the hydration treatment preferably has a carbon dioxide content of less than 300 mg / L, including free non-ionized carbonic acid and ionized hydrogen carbonate ion (HCO 3 ⁇ ). If the content of the carbon dioxide is less than 300 mg / L, calcium compounds other than free lime and calcium hydroxide are hardly eluted in water used for the hydration treatment, so that most of the calcium contained in the steelmaking slag is CO 2 It can be eluted into the aqueous CO 2 solution at the time of contact with the aqueous solution (step S120), and the recovery of calcium does not easily become complicated.
  • the water has a high carbon dioxide content
  • calcium eluted from free lime or calcium hydroxide reacts with carbon dioxide, and the generated and precipitated calcium carbonate covers the surface of the slag particles, and the hydration reaction proceeds
  • the content of carbon dioxide is less than 300 mg / L, inhibition of the hydration reaction due to the precipitation of calcium carbonate is unlikely to occur.
  • the content of the carbon dioxide in the industrial water is usually less than 300 mg / L. Therefore, it is preferable that the water used for the hydration treatment by immersion standing or immersion stirring is industrial water to which carbon dioxide is not intentionally added or contained.
  • the temperature of the water used for the hydration treatment may be a temperature at which the water does not evaporate violently.
  • the temperature of water when hydrating steelmaking slag under conditions of approximately atmospheric pressure, the temperature of water is preferably 100 ° C or lower.
  • the temperature of the water when performing hydration at a higher pressure using an autoclave or the like, the temperature of the water may be 100 ° C or higher as long as the temperature is not higher than the boiling point of water at the pressure at which the hydration is performed.
  • the temperature of water when performing hydration treatment by immersion standing or immersion stirring is preferably 0 ° C or more and 80 ° C or less.
  • the temperature is preferably 300 ° C. or less from the viewpoint of the pressure resistance of the apparatus and economical aspects.
  • the temperature at which the hydration treatment is performed by pasting and standing is preferably 0 ° C. or more and 70 ° C. or less.
  • the duration of the hydration treatment can be arbitrarily set depending on the average particle diameter of the slag, the temperature at which the hydration treatment is performed (temperature of water or air containing water vapor), and the like.
  • the duration of the hydration treatment may be shorter as the average particle diameter of the slag is smaller, and may be shorter as the temperature of the hydration treatment is higher.
  • the duration of the hydration treatment may be about 8 hours continuously. It is preferable that the heating time be 3 hours or more and 30 hours or less.
  • the duration of the hydration treatment is continuously 0.6 hours or more and 8 hours or less.
  • the duration of the hydration treatment is continuously 0.1 hours or more.
  • the time is preferably not more than 0.2 hours, more preferably not less than 0.2 hours and not more than 3 hours.
  • the duration of the hydration treatment is such that the maximum particle size of the slag particles is 1000 ⁇ m or less, preferably 500 ⁇ m or less, more preferably 250 ⁇ m, and still more preferably It is preferable to perform the process until the thickness becomes 100 ⁇ m or less.
  • the hydration treatment is preferably carried out to such an extent that calcium silicate is sufficiently converted into a hydrate and calcium hydroxide, or calcium iron aluminum oxide is sufficiently converted into a calcium oxide-based hydrate.
  • the hydration treatment is preferably performed until the amount of calcium silicate contained in the steelmaking slag becomes 50% by mass or less, or until the amount of calcium iron aluminum oxide becomes 20% by mass or less.
  • the steelmaking slag after the hydration treatment may be used as it is for contact with a CO 2 aqueous solution (step S120).
  • the steelmaking slag when the steelmaking slag is in a slurry state, the steelmaking slag and the liquid component are separated by solid-liquid separation.
  • the solid-liquid separation can be performed by a known method including filtration under reduced pressure and filtration under pressure.
  • the liquid component obtained by the solid-liquid separation (hereinafter simply referred to as “hydration-treated water”) contains calcium eluted from steelmaking slag in addition to the water used for the hydration treatment. It has become. Therefore, in the second embodiment, the hydration-treated water can be used as a calcium-based alkaline substance for further increasing the pH of the CO 2 aqueous solution.
  • a calcium-based alkaline substance is introduced into the CO 2 aqueous solution (step S150), and thereafter, The solid component containing calcium precipitated on the surface may be recovered (Step S140).
  • FIG. 9 is a flowchart of a method for recovering calcium from steelmaking slag according to a fourth embodiment of the present invention.
  • a steelmaking slag is prepared (step S110), and then the steelmaking slag is subjected to magnetic separation (step S170). Then, contacting the steel slag subjected to the magnetic separator to CO 2 aqueous solution (step S120), steelmaking slag is sprayed the CO 2 solution in contact (step S130), recovering a solid component comprising a precipitated calcium (step S140).
  • Step S110, step S120, step S130, and step S140 can be performed in the same manner as in the first embodiment, and thus redundant description will be omitted.
  • the calcium iron aluminum oxide contained in the steelmaking slag is hardly magnetized after Ca is eluted by contact with a CO 2 aqueous solution, and is not easily recovered by magnetic separation.
  • By performing magnetic separation before contact with the CO 2 aqueous solution calcium iron aluminum oxide in the steelmaking slag can also be recovered, and iron derived from calcium iron aluminum can be more easily reused.
  • the magnetic separation can be performed using a known magnetic separator.
  • the magnetic separator may be either a dry type or a wet type, and can be selected according to the state of the steelmaking slag (dry state or slurry state).
  • the magnetic separator can be appropriately selected from a drum type, a belt type, a flow type between fixed magnets, and the like.In particular, it is easy to sort steelmaking slag contained in the slurry, and the magnetic force is increased to increase the magnetic separation amount.
  • a drum type is preferable because it is easy.
  • the magnet used by the magnetic force sorter may be a permanent magnet or an electromagnet.
  • the magnetic flux density by the magnet may be such that the ferrous compound and metallic iron can be selectively captured from other compounds contained in the steelmaking slag.
  • the magnetic flux density can be set to 0.003T or more and 0.5T or less. It is preferably between 0.005T and 0.3T, and more preferably between 0.01T and 0.15T.
  • the time and the number of times of the magnetic separation may be appropriately selected according to the influence of the magnetic separation on the manufacturing cost.
  • the steelmaking slag is preferably subjected to a heat treatment before magnetic separation.
  • a heat treatment is preferably performed at 300 ° C. or more and 1000 ° C. or less for 0.01 minutes or more and 60 minutes or less.
  • the steelmaking slag may be in a dry state at the time of magnetic separation, but is preferably in the form of a slurry dispersed in water.
  • Slurry-like steelmaking slag is apt to disperse slag particles due to the polarity of water molecules, water flow, and the like, so that it is easy to selectively capture iron-based compounds and metallic iron by magnetic force.
  • the particle diameter of the slag particles is 1000 ⁇ m or less
  • the slag particles are formed by a liquid bridging force due to condensation of water vapor in the atmosphere, a van der Waals force between the slag particles, an electrostatic force between the slag particles, and the like.
  • the slag particles can be sufficiently dispersed by forming the slurry.
  • the metallic iron in the steelmaking slag is minute, it is difficult to catch the ironmaking slag when the steelmaking slag is dry.
  • the metallic iron dispersed in water is also easily captured by magnetic separation.
  • the slurry from which the iron-based compound and metallic iron have been removed by magnetic separation may be used as it is for contact with a CO 2 aqueous solution (step S120), but when the steelmaking slag is in a slurry state, it is subjected to solid-liquid separation to produce steel.
  • the slag and the liquid component are separated.
  • the solid-liquid separation can be performed by a known method including filtration under reduced pressure and filtration under pressure.
  • the liquid component obtained by the solid-liquid separation (herein, also simply referred to as “magnetically separated water”) contains calcium eluted from the steelmaking slag in addition to the water used for slurrying, and thus becomes alkaline. I have. Therefore, the magnetic separation water can be used as a calcium-based alkaline substance for further increasing the pH of the CO 2 aqueous solution in the second embodiment.
  • the magnetically separated slag removed from the steelmaking slag by the magnetic separation contains a large amount of a compound containing Fe such as an iron compound and metallic iron as described above, it can be reused as a raw material for a blast furnace or sintering.
  • the steelmaking slag is preferably subjected to a heat treatment before the magnetic separation.
  • a heat treatment is preferably performed at a temperature of 300 ° C. or more and 1000 ° C. or less for 0.01 minute or more and 180 minutes or less.
  • a calcium-based alkaline substance is introduced into the CO 2 aqueous solution (step S150), and thereafter, The solid component containing calcium precipitated on the surface may be recovered (Step S140).
  • the hydration treatment may be performed on the steelmaking slag before being brought into contact with the CO 2 aqueous solution.
  • any of the hydration treatment and the magnetic separation may be performed first, or the wet magnetic separation is performed, or the slurry subjected to the wet magnetic separation is circulated. , May be performed simultaneously. If any of these is performed first, the hydration treatment (particularly hydration treatment by immersion and stirring) is performed first, and then magnetic separation increases the calcium recovery rate, especially when the apparatus is upsized. In addition, the entire process can be performed in a shorter time.
  • Example 1 A steelmaking slag having the component ratio shown in Table 1 was prepared. The components of the steelmaking slag were measured by a chemical analysis method.
  • the steelmaking slag shown in Table 1 was pulverized to a diameter of 8 mm or less, and then heated at 750 ° C for 20 minutes. After heating, the steelmaking slag was air-cooled to room temperature. Thereafter, the steelmaking slag was further pulverized and then passed through a sieve having an opening of 106 ⁇ m, and used for the subsequent treatment.
  • Example 1 (Hydration treatment: hydration by ball mill) A ball mill having an inner diameter of 500 mm was prepared. 1 kg of steelmaking slag not subjected to magnetic separation was charged into the ball mill, and 1 L of water was charged to turn the steelmaking slag into a slurry. Further, 6 kg of alumina balls (crushing medium) were charged into the ball mill. The diameter of the ball was 10 mm. Thereafter, the ball mill was rotated at 50 rpm, and the rotating balls were brought into contact with the steelmaking slag to pulverize the steelmaking slag and the like. By this hydration while pulverizing, the particle diameter (d90) of the slag became 20 ⁇ m. Carbon dioxide was not introduced into the slurry steelmaking slag.
  • Magnetic selection Water was added to the hydrated slurry steelmaking slag so that the slurry volume became 40 L. This slurry was put into a drum type magnetic separator, and magnetically selected under the conditions of a maximum magnetic flux density of 0.07 T on the drum surface and a drum peripheral speed of 40 m / min. When the iron concentration in the steelmaking slag after the magnetic separation was measured by a chemical analysis method and the weight was measured, 41% by mass of the iron element contained in the first steelmaking slag was removed. After the magnetic separation, the remaining slurry was filtered to separate the remaining slag.
  • the magnetically separated water which is an aqueous solution from which the residual calcium was leached after the residual slag was separated, was set aside for the subsequent process.
  • the calcium concentration of the magnetic separation water was 480 mg / L. In a preliminary experiment, it was confirmed that slag having a dry weight of 0.15 kg was separated by magnetic separation.
  • the elution / sedimentation tank was a cylindrical container having an inner diameter of 480 mm, and was provided with an impeller that rotated along the bottom surface so that the steelmaking slag that had settled and accumulated moved to the suction port. The impeller was rotated at 40 rpm. The remaining slag collected by the filtration after the magnetic separation step was put into the elution / sedimentation tank without drying, and water was added so that the slurry amount became 100 L. At this time, the ratio of water to slag was approximately 120: 1.
  • the steelmaking slag collected from the bottom was sent to a pulverizing unit by a pump, and was pulverized by a continuous pulverizer using a ball mill.
  • the pulverizing part was a horizontal cylindrical shape having an inner diameter of 200 mm, and a ball of ⁇ 10 mm was placed therein at 70% of the total volume.
  • 20 L / min of carbon dioxide was introduced into the pipe section between the elution / settling tank and the pulverizing section. The contact with the CO 2 aqueous solution was performed for 30 minutes.
  • the calcium-eluted slurry obtained as described above was filtered and separated from the slag to obtain a calcium-eluted CO 2 aqueous solution.
  • the pH of the aqueous CO 2 solution was 6.6, and the calcium concentration was 1,230 mg / L.
  • the pH of the aqueous CO 2 solution after spraying twice was 8.0, and the calcium concentration was 61 mg / L.
  • the carbon dioxide concentration of the gas discharged from the closed container during the experiment was measured by an infrared method, and was about 10%.
  • the concentration of carbon dioxide in this gas was higher than the concentration of carbon dioxide in exhaust gas from a general natural gas-fired power plant (about 9%), and was such that recovery and purification could be easily performed.
  • the calcium hydroxide-based composition-1 (the magnetic separation obtained in the above magnetic separation step) was added to the aqueous CO 2 solution (pH: 7.0, calcium concentration: 190 mg / L, calcium deposition rate: 84.5%) stored in the tank.
  • Water calcium hydroxide composition-2 (aqueous solution prepared by dissolving calcium hydroxide in water), and calcium hydroxide composition-3 (solid calcium hydroxide is dispersed in calcium hydroxide water) Slurry prepared in advance) was added while stirring the CO 2 solution.
  • the amount of each CO 2 aqueous solution was adjusted so that the pH of the CO 2 aqueous solution became 8.0, 8.5, 9.0, or 9.5.
  • Table 2 shows the pH and calcium concentration of the calcium hydroxide composition-1 to calcium hydroxide composition-3 charged above.
  • the calcium concentration of the calcium hydroxide-based composition-3 which is a slurry, is an average concentration including the solid content.
  • the calcium precipitation rate is 90% or more, and when the pH of the aqueous CO 2 solution after the addition of calcium hydroxide is 8.5 or more.
  • the calcium deposition rate was 94% or more, and the calcium deposition rate was 95% or more when the pH of the CO 2 aqueous solution after the addition of calcium hydroxide was 9.0 or more.
  • the calcium-eluted slurry obtained as described above was filtered and separated from the slag to obtain a calcium-eluted CO 2 aqueous solution.
  • the pH of the CO 2 aqueous solution was 6.7, and the calcium concentration was 1390 mg / L.
  • the pH of the aqueous CO 2 solution was 6.9, and the calcium concentration was 230 mg / L. At this time, the calcium deposition rate was 83.5%.
  • PHTable 4 shows the pH and calcium concentration of the calcium hydroxide composition-4 charged above.
  • the present invention is useful as a method for recovering calcium resources in iron making, since calcium eluted in a CO 2 aqueous solution from steelmaking slag can be precipitated by a simpler method.
  • dissolution apparatus 110 dissolution / sedimentation tank 112 slurry outlet 114 slurry re-introduction port 118 impeller 119 rotary rod 120 pulverizing unit 130 carbon dioxide introduction unit 140 slurry flow path 142 slurry flow path 144 slurry flow path 146 pump 200, 200a, 200b spray device 210,210a closed container 212 CO 2 solution outlet port 214 stirring blade 216 rotational rod 220,220a spray device 222 CO 2 solution passage 224 showerhead 226 nozzles 230 gas inlet 240 gas outlet 250 pump 260 heater 270 alkaline material input mouth

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Metallurgy (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Environmental & Geological Engineering (AREA)
  • Structural Engineering (AREA)
  • Carbon Steel Or Casting Steel Manufacturing (AREA)
  • Processing Of Solid Wastes (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
  • Furnace Details (AREA)

Abstract

Le but de la présente invention est de fournir un procédé de récupération de calcium à partir de laitier d'affinage d'acier dans lequel il est possible, par un procédé plus simple, de précipiter le calcium élué à partir de laitier d'affinage d'acier dans une solution aqueuse de CO2. Pour atteindre l'objectif ci-dessus, la présente invention concerne un procédé de récupération de calcium à partir de laitier d'affinage d'acier. Le procédé comprend : une étape de mise en contact de laitier d'affinage d'acier avec une solution aqueuse de CO2, qui est une solution aqueuse contenant du dioxyde de carbone; et une étape de pulvérisation de la solution aqueuse de CO2 avec laquelle le laitier d'affinage d'acier a été mis en contact.
PCT/JP2019/033881 2018-09-20 2019-08-29 Procédé permettant la récupération de calcium à partir de laitier d'affinage d'acier WO2020059455A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2018-175965 2018-09-20
JP2018175965A JP2020045260A (ja) 2018-09-20 2018-09-20 製鋼スラグからカルシウムを回収する方法

Publications (1)

Publication Number Publication Date
WO2020059455A1 true WO2020059455A1 (fr) 2020-03-26

Family

ID=69888719

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2019/033881 WO2020059455A1 (fr) 2018-09-20 2019-08-29 Procédé permettant la récupération de calcium à partir de laitier d'affinage d'acier

Country Status (3)

Country Link
JP (1) JP2020045260A (fr)
TW (1) TW202012643A (fr)
WO (1) WO2020059455A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI766691B (zh) * 2021-05-20 2022-06-01 中國鋼鐵股份有限公司 電爐煉鋼的方法
TWI775369B (zh) * 2021-03-26 2022-08-21 賴世宗 金屬冶煉爐渣之金屬回收方法及其回收系統
CN115672950A (zh) * 2022-09-20 2023-02-03 原初科技（北京）有限公司 一种钢渣固碳装置及其使用方法
CN115889399A (zh) * 2022-11-26 2023-04-04 安徽华塑股份有限公司 一种电石渣回收利用设备

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS621832A (ja) * 1985-02-07 1987-01-07 Sumitomo Metal Ind Ltd 溶銑処理スラグからのアルカリ金属回収方法
WO2018135439A1 (fr) * 2017-01-18 2018-07-26 日新製鋼株式会社 Procédé d'élution et de récupération du calcium contenu dans le laitier d'aciérie

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS621832A (ja) * 1985-02-07 1987-01-07 Sumitomo Metal Ind Ltd 溶銑処理スラグからのアルカリ金属回収方法
WO2018135439A1 (fr) * 2017-01-18 2018-07-26 日新製鋼株式会社 Procédé d'élution et de récupération du calcium contenu dans le laitier d'aciérie

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI775369B (zh) * 2021-03-26 2022-08-21 賴世宗 金屬冶煉爐渣之金屬回收方法及其回收系統
TWI766691B (zh) * 2021-05-20 2022-06-01 中國鋼鐵股份有限公司 電爐煉鋼的方法
CN115672950A (zh) * 2022-09-20 2023-02-03 原初科技（北京）有限公司 一种钢渣固碳装置及其使用方法
CN115889399A (zh) * 2022-11-26 2023-04-04 安徽华塑股份有限公司 一种电石渣回收利用设备
CN115889399B (zh) * 2022-11-26 2024-05-17 安徽华塑股份有限公司 一种电石渣回收利用设备

Also Published As

Publication number Publication date
JP2020045260A (ja) 2020-03-26
TW202012643A (zh) 2020-04-01

Similar Documents

Publication Publication Date Title
WO2020059455A1 (fr) Procédé permettant la récupération de calcium à partir de laitier d'affinage d'acier
JP6794842B2 (ja) 製鋼スラグからカルシウムを溶出させる方法、および製鋼スラグからカルシウムを回収する方法
JP6927033B2 (ja) 製鋼スラグからカルシウムを回収する方法
TWI679282B (zh) 從煉鋼爐渣回收含有鈣的固體成分的方法
Mattila et al. Production of precipitated calcium carbonate from steel converter slag and other calcium-containing industrial wastes and residues
WO2015114703A1 (fr) Procédé de récupération de phosphore et de calcium et mélange produit par ledit procédé de récupération
WO2014005227A1 (fr) Stabilisation de laitier à l'aide de dioxyde de carbone capturé
CN106277417A (zh) 含镁的冶炼废水综合回收的方法
Wang et al. Sustainable process for enhanced CO2 mineralization of calcium silicates using a recyclable chelating agent under alkaline conditions
CN106999947A (zh) 用于从钢铁渣回收产品的方法和系统
JP2008149234A (ja) 石炭灰の改質方法
KR101303051B1 (ko) 슬래그 처리장치 및 처리방법
Cheng et al. CO2 sequestration and CaCO3 recovery with steel slag by a novel two-step leaching and carbonation method
WO2019107116A1 (fr) Procédé ainsi que dispositif d'élution de calcium à partir de scories d'élaboration d'acier, et procédé de récupération de calcium à partir de scories d'élaboration d'acier
EP4101519B1 (fr) Réacteur pour la minéralisation accélérée du dioxyde de carbone et procédé correspondant
WO2019107115A1 (fr) Procédé ainsi que dispositif d'élution de calcium à partir de scories d'élaboration d'acier, et procédé de récupération de calcium à partir de scories d'élaboration d'acier
JP2004292806A (ja) 土壌修復剤および土壌修復方法
JP2004149829A (ja) 鉄粉の製造方法および土壌浄化剤
JP2014004582A (ja) 硫黄を含有するスラグの硫黄除去処理方法
JP5748925B1 (ja) リンおよびカルシウムの回収方法および前記回収方法によって得られる混合物
CN111807598B (zh) 一种电场协同磷尾矿无害化处理电解锰渣渗滤液的方法
KR20220101979A (ko) 건식 배연탈황설비의 폐기물을 처리하는 방법

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 19862929

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 19862929

Country of ref document: EP

Kind code of ref document: A1