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WO2019107116A1 - 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 - Google Patents

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 Download PDF

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Publication number
WO2019107116A1
WO2019107116A1 PCT/JP2018/041634 JP2018041634W WO2019107116A1 WO 2019107116 A1 WO2019107116 A1 WO 2019107116A1 JP 2018041634 W JP2018041634 W JP 2018041634W WO 2019107116 A1 WO2019107116 A1 WO 2019107116A1
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Prior art keywords
steelmaking slag
calcium
slurry
elution
carbon dioxide
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PCT/JP2018/041634
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English (en)
Japanese (ja)
Inventor
康 福居
昭広 浅場
裕介 空田
義治 岩水
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Nippon Steel Nisshin Co Ltd
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Nisshin Steel Co Ltd
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    • 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
    • B09B3/30—Destroying solid waste or transforming solid waste into something useful or harmless involving mechanical treatment
    • B09B3/35—Shredding, crushing or cutting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C1/00—Magnetic separation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C1/00—Magnetic separation
    • B03C1/005—Pretreatment specially adapted for magnetic separation
    • B03C1/015—Pretreatment specially adapted for magnetic separation by chemical treatment imparting magnetic properties to the material to be separated, e.g. roasting, reduction, oxidation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C1/00—Magnetic separation
    • B03C1/02—Magnetic separation acting directly on the substance being separated
    • B03C1/30—Combinations with other devices, not otherwise provided for
    • 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 
    • 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 of eluting calcium from steelmaking slag, a method of recovering calcium from steelmaking slag, and an apparatus for eluting calcium from steelmaking slag.
  • Steelmaking slag (such as converter slag, pretreated slag, secondary refining slag and electric furnace slag) generated in the steelmaking process is used in a wide range of applications including cement materials, road base materials for roads, civil engineering materials and fertilizers (non-patented) See documents 1 to 3).
  • some steelmaking slags not used for the above applications are disposed of in landfills.
  • steelmaking slag 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 contained most in steelmaking slag is calcium used in large amounts in the steelmaking process, and usually Fe is next contained in a large amount.
  • about 20% by mass to about 50% by mass is calcium, and about 1% by mass to about 30% by mass is Fe.
  • the calcium in steelmaking slag is the reaction of free lime (CaO) and free lime (CaO) deposited in the solidification of steelmaking slag, as the raw lime (CaO) supplied in the steelmaking process remains or as it reacts with water vapor or carbon dioxide in the air.
  • Calcium carbonate and calcium oxide are main slag forming materials in iron making process and steel making process in iron making process, and are used as a modifier of basicity and viscosity of the slag and as a dephosphorization agent from molten steel There is.
  • calcium hydroxide obtained by watering calcium oxide is used as a neutralizing agent such as acid in a drainage process. Therefore, it is expected that the cost of steelmaking can be reduced if the Ca compound contained in the steelmaking slag is recovered and reused in the steelmaking process.
  • Calcium in steelmaking slag can be recovered, for example, 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 salts of calcium and the acid formed in this method are difficult to reuse.
  • calcium chloride produced by eluting calcium in steelmaking slag into hydrochloric acid can be reused if it is heated to form oxides, but there is a problem that the processing cost of harmful chlorine gas generated during the above heating is high .
  • calcium in the steelmaking slag is eluted and recovered in an acidic aqueous solution, there is also a problem that the cost of purchasing the acid and discarding the acid after the elution process is high.
  • Patent Document 1 describes a method of blowing carbon dioxide into an aqueous solution in which calcium in a converter slag is eluted, and recovering precipitated calcium carbonate. At this time, the lower limit value of pH is maintained at about 10 in order to suppress the formation of calcium hydrogen carbonate having high solubility in water. Although a specific method for maintaining the pH at 10 or more is not described in Patent Document 1, it is considered that the pH is maintained at 10 or more by adjusting the blowing amount of carbon dioxide.
  • Patent Document 2 a crushed steelmaking slag is separated into an iron-enriched phase and a phosphorus-enriched phase, and the Ca compound in the phosphorus-enriched phase is dissolved in washing water in which carbon dioxide is dissolved, and then 50 to 60 washing waters.
  • a method is disclosed in which calcium hydrogen carbonate in wash water is precipitated as calcium carbonate by heating to about ° C. and recovered.
  • Patent Document 3 describes a method for separating and recovering a Ca compound in multiple steps from a steelmaking slag. In this method, it is described that by immersing steelmaking slag (pretreated slag) a plurality of times in water blown with carbon dioxide, the 2CaO ⁇ SiO 2 phase and phosphorus dissolved in this phase are preferentially eluted There is.
  • Fe in steelmaking slag is present as iron-based oxide, calcium iron aluminum oxide, and metallic iron, although in a very small amount.
  • the iron-based oxide contains not only Mn or Mg but also a small amount of elements such as Ca, Al, Si, P, Ti, Cr and S.
  • calcium iron aluminum also contains a small amount of elements such as Si, P, Ti, Cr and S.
  • the iron-based oxide also includes a compound in which a portion of the surface has been converted to a hydroxide or the like by water vapor in the air, and calcium iron aluminum oxide also contains water vapor and carbon dioxide in the air It also includes a compound in which part of its surface has been changed to hydroxide or carbonate by the
  • 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 ).
  • wustite-based oxide and hematite-based oxide can be separated from steelmaking slag by magnetic separation because magnetite-based oxide (Fe 3 O 4 ), which is a ferromagnetic substance, is dispersed therein.
  • magnetite-based oxides which are present alone or coexist with other iron-based oxides can also be separated from steelmaking slag by magnetic separation.
  • Patent Documents 4 to 6 describe a method of reforming wustite-based oxides to magnetite-based oxides by oxidation treatment or the like in order to separate more iron-based oxides by magnetic separation.
  • the calcium iron aluminum is magnetized to become a magnetic body, it can be separated from the steelmaking slag by magnetic separation as well.
  • Iron-based oxides and calcium-iron-aluminum oxide (hereinafter collectively referred to as "iron-based compound”.
  • Calcium-iron-aluminum oxide is a Ca compound and an iron-based compound at the same time.) Since the content is as small as 0.1% by mass or less, it can be used as a material for blast furnace and sintering if it is separated and recovered from steelmaking slag by the above-described magnetic separation and the like.
  • the metallic iron is Fe which is caught in the slag in the steelmaking process, or fine Fe which precipitates out during solidification of the steelmaking slag. Large metallic iron is removed by magnetic separation or other methods in a dry process of crushing or crushing steelmaking slag in the atmosphere.
  • this washing solution is mixed with a solution leached with mineral acid, and the solution leached with mineral acid is neutralized to precipitate calcium carbonate, the mixture is acidified with mineral acid to dissolve calcium in the aqueous solution.
  • the amount (solubility) increases. Therefore, even if calcium carbonate precipitates, a large amount of calcium remains in the mixed solution, and the calcium recovery efficiency is degraded.
  • Patent Literatures 1 and 2 do not suggest any device for increasing the elution amount of the Ca compound to the CO 2 aqueous solution. Further, in the method described in Patent Document 3, if the number of steps of dissolving the Ca compound is increased, it is considered that the total elution amount of calcium is also increased, but in this method, as described above, the steps become complicated and recovered. There is a problem that the cost becomes high.
  • the present invention can easily elute more calcium from steelmaking slag from a steelmaking slag into CO 2 aqueous solution, can elute calcium from steelmaking slag and can elute calcium from the steelmaking slag It is an object of the present invention to provide an apparatus and a method of recovering calcium eluted by this method.
  • the present invention causes steelmaking slag contained in a slurry containing steelmaking slag and to which carbon dioxide is introduced to settle in the inside of the elution / settling tank to increase the concentration of the steelmaking slag in the slurry.
  • the present invention also relates to a method for recovering calcium from steelmaking slag, which comprises the steps of eluting calcium from steelmaking slag by the above method, and recovering the eluted calcium.
  • a slurry containing steelmaking slag is introduced, and a slurry in which the concentration of the steelmaking slag is raised is taken out by settling of the steelmaking slag inside, and it is taken out from the elution / settling tank
  • concentration of the steelmaking slag is increased by the above-mentioned sedimentation taken out from the elution / settling tank, and a grinding unit for grinding or grinding the surface of the steelmaking slag contained in the slurry taken out or grinding the steelmaking slag contained in the slurry
  • the present invention relates to an apparatus for eluting calcium from steelmaking slag, including a carbon dioxide inlet.
  • the present invention it is possible to easily dissolve a large amount of calcium from steelmaking slag to a CO 2 aqueous solution, a method of eluting calcium from steelmaking slag, an apparatus capable of performing the method of eluting calcium from the steelmaking slag, Methods are provided for recovering eluted calcium.
  • FIG. 1 is a schematic view showing the configuration of an apparatus used to elute calcium from steelmaking slag in the first embodiment of the present invention.
  • FIG. 2A is a schematic view showing an exemplary form of a grinding unit included in an apparatus used for eluting calcium from steelmaking slag
  • FIG. 2B is a grinding unit included in an apparatus used for eluting calcium from steelmaking slag.
  • FIG. 7 is a schematic view showing another exemplary embodiment of the present invention.
  • FIG. 3A is a schematic view showing an exemplary embodiment of the stirring impeller of the crushing unit shown in FIG. 2B
  • FIG. 3B is a schematic view showing an exemplary embodiment of the stirring screw of the crushing unit shown in FIG. is there.
  • FIG. 3A is a schematic view showing an exemplary embodiment of the stirring impeller of the crushing unit shown in FIG. 2B
  • FIG. 3B is a schematic view showing an exemplary embodiment of the stirring screw of the crushing unit shown in FIG. is there.
  • FIG. 4 is a schematic view showing the configuration of still another apparatus used to elute calcium from steelmaking slag in the first embodiment of the present invention.
  • FIG. 5A and FIG. 5B are schematic views showing how the slurry takeout rate is changed in an apparatus used to elute calcium from steelmaking slag in the first embodiment of the present invention.
  • FIG. 6 is a schematic view showing the configuration of still another apparatus used to elute calcium from steelmaking slag in the first embodiment of the present invention.
  • FIG. 7 is a schematic view showing the configuration of still another apparatus used to elute calcium from steelmaking slag in the first embodiment of the present invention.
  • FIG. 5A and FIG. 5B are schematic views showing how the slurry takeout rate is changed in an apparatus used to elute calcium from steelmaking slag in the first embodiment of the present invention.
  • FIG. 6 is a schematic view showing the configuration of still another apparatus used to elute calcium from steelmaking slag in the first embodiment of the present invention.
  • FIG. 7 is
  • FIG. 8 is a flow chart illustrating exemplary steps of a method of eluting calcium from steelmaking slag according to a second embodiment of the present invention.
  • FIG. 9 is a flow chart illustrating exemplary steps of a method of eluting calcium from steelmaking slag according to a third embodiment of the present invention.
  • FIG. 10 is a flow chart of a method of recovering calcium from steelmaking slag according to the present invention.
  • FIG. 11 is a flow chart showing an example of the step of recovering calcium in the method of recovering calcium from steelmaking slag according to the present invention.
  • FIG. 12 is a graph showing the relationship between the proportion of each carbonic acid species present in the aqueous CO 2 solution and the pH.
  • Pulverization refers to mechanically giving energy to target particles (particles of steelmaking slag) to break them and reducing their size.
  • a method of mechanically applying energy there is a method of moving a grinding medium such as a ball and bringing it into contact with target particles, and a method of making parts of a device such as a roller and a hammer move and make contact with target particles. Simply stirring the target particles does not provide enough energy to destroy the target particles and reduce their size, as the target particles only move with the slurry flow.
  • calcium in steelmaking slag is 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 in a form such as iron aluminum (Ca 2 (Al 1 -x Fe x ) 2 O 5 ).
  • free lime is easily dissolved in a CO 2 aqueous solution, it is usually contained in the steelmaking slag only at less than about 10% by mass.
  • calcium silicate is generally contained in about 25% by mass to 70% by mass in steelmaking slag
  • calcium iron aluminum is usually contained in about 2% by mass to about 30% by mass in steelmaking slag. Therefore, if the calcium contained in Ca compounds other than free lime (such as calcium silicates and calcium oxide iron aluminum) easily eluted with CO 2 aqueous solution, to increase the dissolution of calcium into CO 2 solution from steelmaking slag It is considered possible to recover calcium from steelmaking slag in a shorter time.
  • calcium has high solubility in an aqueous solution of CO 2, but silicon, aluminum, iron and the like have low solubility in an aqueous solution of CO 2 . Therefore, when calcium silicate and calcium iron oxide dissolve in the aqueous solution of CO 2 , calcium elutes, but silicon, aluminum and iron etc. become hydroxide, carbonate or hydrate surface of steel slag May remain in the In addition, silicon, aluminum, iron and the like, which have low solubility in a CO 2 aqueous solution, may precipitate on the surface of steelmaking slag after being eluted once. In addition, iron and manganese contained in iron oxide and calcium iron oxide aluminum in steelmaking slag also have low solubility.
  • iron oxide or calcium iron oxide aluminum elutes slightly in a CO 2 aqueous solution
  • iron or manganese may be precipitated on the surface of steelmaking slag. It is thought that the elution rate of calcium is slower than the ideal state because these substances remaining or precipitated on the surface of the steelmaking slag prevent the contact between the CO 2 aqueous solution and the surface of the steelmaking slag.
  • the elution of calcium from the steelmaking slag is caused by the contact of the Ca compound and water near or in the surface of the steelmaking slag.
  • the amount of contact with water is larger in the vicinity of the surface. Therefore, calcium is more likely to be eluted near the surface of the steelmaking slag.
  • the components contained in steelmaking slag are dissolved in the aqueous solution of CO 2 used for elution of calcium, as described above, silicon, aluminum, iron and manganese or their hydroxides, carbonates and hydrates etc. It may remain or precipitate on the surface of the slag. When these remaining or precipitated substances inhibit the penetration of the aqueous solution of CO 2 into the inside of the steelmaking slag, calcium is less likely to be eluted from the inside of the steelmaking slag.
  • grinding the steelmaking slag forms a new surface on which the above substance has not yet remained or precipitated, and the CO 2 aqueous solution is allowed to permeate from the continuously formed surface to the inside of the steelmaking slag.
  • the CO 2 aqueous solution is allowed to permeate from the continuously formed surface to the inside of the steelmaking slag.
  • calcium can be easily eluted from the inside of the steelmaking slag.
  • granular steelmaking slag hereinafter, also simply referred to as "slag particles” by crushing steelmaking slag etc.
  • steelmaking slag it is crushed or crushed into slag particles and particles). This means that the surface area of CO 2 aqueous solution and slag particles can be made larger by increasing the surface area of both.
  • the contact area between the CO 2 aqueous solution and the slag particles becomes larger, and the CO 2 aqueous solution is contained inside the slag particles. It becomes easy to penetrate.
  • Slag particles in the slurry are more likely to settle as the particle size is larger. Therefore, in the method of the present embodiment, since the particle size is large, the surface area per volume is small, and the slag particles in which the elution of calcium from the surface and the penetration of the CO 2 aqueous solution into the inside are difficult to occur are precipitated. Move to the area on the bottom side of the column and take it out of the elution / settling tank. The removed slag particles are ground or the like in a grinding portion outside the elution / settling tank, and contact with a CO 2 aqueous solution efficiently forms a new surface on which calcium is easily eluted. Slag particles whose particle size has become smaller due to grinding etc. are reintroduced into the elution / settling tank, but since they are less likely to settle, the contact time with the CO 2 aqueous solution becomes longer and calcium can be eluted more efficiently. .
  • Pulverization etc. can be efficiently performed by selectively taking out the slurry containing these settled steelmaking slags from an elution / sedimentation tank and introduce
  • the height of the elution / settling tank should be 0.2 m or more, preferably 0.3 m or more, more preferably 0.5 m or more, from the viewpoint of settling the steelmaking slag in the lower part.
  • the pressure (hydrostatic pressure) of the slurry in the region on the bottom side of the elution / settling tank is increased, and the amount of carbon dioxide dissolved in the slurry is increased.
  • the amount of calcium eluted from steelmaking slag increases. For example, if the slurry height is increased by 10 m, the amount of carbon dioxide dissolved will be approximately doubled.
  • the upper limit of the height of the elution / settling tank is not particularly limited, it can be 100.0 m.
  • the flow rate is preferably 100 m / min or less, preferably 50 m / min or less.
  • the slag particles in the slurry are less likely to settle when the particle size is a certain size or less.
  • particles of calcium silicate have a particle size of 1 ⁇ m or less, it takes 24 hours or more to settle 1 m in the slurry. Therefore, in the above method, since the slag particles which become smaller than a certain size and the CO 2 aqueous solution easily penetrates into the inside of the particles and which easily dissolves calcium are difficult to settle, they stay in the elution / settling tank for a long time. Continue to elute.
  • slag particles on the surface of which silicon, aluminum, iron and manganese or their hydroxides, carbonates and hydrates etc. are precipitated are again precipitated due to the large particle size and are crushed and the surface is newly formed. Exposed.
  • slag particles having a large particle size and in which calcium is not easily eluted are introduced into the pulverizing part and pulverized preferentially, while slag particles in which the particle size is small and calcium is easily eluted are dissolution and sedimentation tanks. It can be kept for a long time to keep calcium eluting. Therefore, the above method is more efficient in eluting calcium from steelmaking slag by contact with a CO 2 aqueous solution, as compared with the case where the whole of the slag particles in the slurry is ground or the like using a ball mill or the like. Can be done.
  • a wet crusher is used to smash while moving the entire combination of the slurry and balls like a ball mill etc., the entire slurry is stirred, so steelmaking slag is contacted with the balls in a low concentration state and crushed Ru. Therefore, a wet crusher such as a ball mill has poor efficiency such as crushing of steelmaking slag, and it is difficult to increase the elution amount of calcium. On the other hand, it is also considered that the elution amount of calcium can be increased by increasing the slag concentration and subjecting it to a wet pulverizer such as a ball mill.
  • the concentration of steelmaking slag in the slurry for increasing the elution amount of calcium can be 10 L / kg or more of the ratio of water to steelmaking slag (volume of water / mass of steelmaking slag) 30 L / kg or more is preferable, 50 L / kg or more is more preferable, and 100 L / kg or more is more preferable.
  • the upper limit of the above ratio is not particularly limited, it can be 700 L / kg or less from the viewpoint of enhancing the efficiency such as crushing of settled slag.
  • the said slurry should just be what suspended steelmaking slag in water. From the viewpoint of shortening the time to raise the carbon dioxide concentration of the CO 2 aqueous solution by introducing carbon dioxide and shortening the time to elute calcium, the supplied slurry suspended the steelmaking slag in the CO 2 aqueous solution It may be one.
  • the type of steelmaking slag is not particularly limited as long as it is a slag discharged in the steelmaking process.
  • steelmaking slag include converter slag, pretreated slag, secondary refining slag and electric furnace slag.
  • steelmaking slag may use what was discharged
  • the maximum particle size of the pre-crushed slag particles is preferably 1000 ⁇ m or less. When the maximum particle size is 1000 ⁇ m or less, the surface area per volume is large, and the aqueous solution of CO 2 can sufficiently penetrate into the inside of steelmaking slag, so that a large amount of calcium is eluted by contact with the aqueous solution of CO 2 Can. Steelmaking slag can be crushed or crushed to the above range by a known crusher.
  • the maximum particle size of the slag particles is preferably 500 ⁇ m or less, more preferably 250 ⁇ m or less, and still more preferably 100 ⁇ m or less.
  • the maximum particle size of the slag particles can be reduced to the above range by, for example, further crushing the crushed or crushed slag particles with a grinder including a hammer mill, a roller mill, a ball mill and the like.
  • Steelmaking slag is a filtration residue slag obtained by filtering after making steelmaking slag into a container containing water, leaching of free lime and calcium hydroxide, and leaching of calcium on the surface of a Ca compound. May be By using the filtered residual slag, it is possible to use a slag in which calcium is eluted to some extent, so the load for eluting a larger amount of calcium can be reduced by the present embodiment.
  • the filtered water from which calcium is leached (hereinafter, also simply referred to as “slag leachate”), which is obtained simultaneously at this time, is a highly alkaline aqueous solution having a pH of 11 or more.
  • Slag leaching water can be used for precipitation of a calcium-containing solid component (precipitation step), as described later, when recovering calcium.
  • slag leaching water can be used for applications requiring an alkaline aqueous solution, such as a neutralizing agent for acid wastewater.
  • there is also a merit that kneading of water is not necessary when the hydration treatment is carried out by holding with water, which will be described later, using filtered residual slag.
  • the amount of slag in the slurry is preferably 1 g / L or more and 100 g / L or less, more preferably 2 g / L or more and 40 g / L or less, from the viewpoint of sufficiently eluting calcium in steelmaking slag.
  • the grinding and the like of steelmaking slag in the elution / settling tank has a maximum particle diameter of slag particles of 1000 ⁇ m or less, preferably 500 ⁇ m or less, more preferably 250 ⁇ m, It is more preferable to carry out until it becomes 100 micrometers or less more preferably.
  • the crushed steelmaking slag elutes calcium by contact with a CO 2 aqueous solution.
  • Carbon dioxide may be introduced in advance into the slurry before being introduced into the elution / settling tank.
  • calcium elutes calcium and carbon dioxide react with each other to form water-soluble calcium hydrogen carbonate, so that carbon dioxide in the slurry decreases as calcium dissolves. Therefore, from the viewpoint of enhancing the elution efficiency of calcium, it is preferable to introduce carbon dioxide into the slurry while circulating the slurry between the elution / settling tank and the grinding part.
  • the slurry taken from the elution / settling tank flows until it is reintroduced into the elution / settling tank through the grinding section. It is preferable to introduce carbon dioxide into the slurry in the passage, and the vicinity of the reintroduction port where the slurry in which slag particles are crushed etc. is reintroduced into the elution / sedimentation tank is good.
  • carbon dioxide When carbon dioxide is introduced into the slurry in the elution / settling tank, carbon dioxide may be introduced into the bottom side region of the elution / settling tank where the pressure is increased from the viewpoint of increasing the amount of carbon dioxide dissolved in the slurry. preferable. Further, from the viewpoint of preventing re-floating of the precipitated slag, it is preferable to introduce carbon dioxide at a position above the deposited slag.
  • Carbon dioxide can be introduced into the slurry, for example, by bubbling a gas containing carbon dioxide.
  • a gas containing carbon dioxide such as a gas diffusion tube and a microbubble generator, at a gas inlet for carbon dioxide containing gas.
  • the quantity of free carbonic acid which may 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 may be a gas containing components other than carbon dioxide (for example, oxygen or nitrogen).
  • the gas containing carbon dioxide include exhaust gases after combustion, and a mixed gas of carbon dioxide, air and water vapor.
  • the gas containing carbon dioxide has high carbon dioxide content. It is preferred to include at a concentration (eg, 90%).
  • a gas containing carbon dioxide may be simply referred to as carbon dioxide.
  • FIG. 1 is a schematic diagram which shows the structure of the apparatus used in order to elute calcium from steelmaking slag in this embodiment.
  • a slurry (shaded area in the figure) is introduced, and the elution / settling tank 110 for settling the steelmaking slag and the slurry taken out from the elution / settling tank 110 Pulverizing unit 120 for pulverizing steelmaking slag contained in the elution / settling tank 110, carbon dioxide introducing unit 130 for introducing carbon dioxide into the slurry, and slurry for slurry taken out from the elution / settling tank 110 And a slurry channel 140 for reintroducing the slurry containing the steelmaking slag introduced into 120 and crushed or the like by the crushing unit 120 into the elution / settling tank 110.
  • the elution / settling tank 110 is a container into which the slurry is charged. Among the steelmaking slags contained in the slurry charged into the interior of the vessel, the elution / settling tank 110 settles slag particles having a relatively large particle diameter, and slag particles having a relatively large particle diameter and a relatively small particle diameter. It may be of a size that can separate from slag particles.
  • the elution / settling tank 110 has a slurry outlet 112 on the bottom side and has a slurry reintroduction port 114 on the upper side (liquid surface side) of the slurry outlet 112 to which the slurry from the grinding unit 120 is reintroduced. .
  • the slurry re-introduction port 114 is 0.1 m or more from the liquid surface of the elution / settling tank 110 in order to make it difficult for carbon dioxide contained in the re-introduced slurry to be released from the surface of the slurry to the atmosphere in the elution / settling tank 110. It is preferable to arrange
  • the steelmaking slag having a small particle diameter which has a slow sedimentation (is easy to float)
  • the bottom surface of the elution / settling tank 110 is an inclined surface which is inclined so as to be deep toward the slurry outlet 112 in order to facilitate removal of the deposited steelmaking slag.
  • the grinding unit 120 is in communication with the slurry outlet 112 of the elution / settling tank 110 by the slurry channel 142, and communicates with the slurry re-introduction port 114 of the elution / settling tank 110 by the slurry channel 144.
  • the grinding unit 120 grinds steelmaking slag contained in the slurry introduced from the slurry flow channel 142 and the like.
  • the grinding unit 120 can be configured to flow the grinding medium introduced into the grinding container by stirring. With such a configuration, the fluidized grinding medium 124a or the grinding medium 124b comes into contact with the slag particles, and the grinding medium 124a or the grinding medium 124b that is fluidized and rotates slides the slag particles, and the slag The particles can be crushed more efficiently.
  • FIG. 2A is a schematic view showing a configuration example of a pulverizing unit 120a that rotates the pulverizing container 122a to flow the pulverizing medium 124a.
  • the rotation axis of the grinding container 122a coincides with the slurry flow channel 142 and the slurry flow channel 144, the slurry introduced from the slurry flow channel 142 is stirred by the rotation of the grinding container 122a, and the grinding medium 124a is used.
  • It is a continuous grinding mechanism in which steelmaking slag in the slurry is crushed and the like and discharged to the slurry flow channel 144.
  • the grinding medium 124a may be charged so that it reaches half or more of the height of the grinding container 122a so that steelmaking slag in the slurry flowing along the rotation axis of the grinding container 122a can be sufficiently ground.
  • an amount of 70% by volume with respect to the volume of the grinding container 122a is charged.
  • the volume of the grinding container 122a is not particularly limited, it can be 1 L or more and 500000 L or less.
  • the rotation speed of the grinding container 122a is also not particularly limited, and can be 1 rpm or more and 200 rpm or less.
  • FIG. 2B is a schematic view showing a configuration example of the pulverizing unit 120b which causes the pulverizing medium 124b to flow by the rotation of the stirring mechanism 126 disposed inside the pulverizing container 122b.
  • the grinding container 122b communicates with the slurry flow channel 142 on the bottom side of the container, and with the slurry flow channel 144 on the upper (liquid surface) side of the container, so that the slurry-like steelmaking slag crushed is etc. It is a continuous grinding mechanism that discharges into
  • the grinding medium 124b is preferably charged so that it reaches half or more of the height of the grinding container 122b so that steelmaking slag in the slurry flowing in the grinding container 122b can be sufficiently ground.
  • an amount of 50% by volume with respect to the volume of the grinding container 122b is introduced.
  • the stirring mechanism 126 may be any mechanism as long as it can stir the grinding medium 124b and grind the slag particles.
  • the stirring mechanism 126 can be a plurality of stirring impellers 126a shown in FIG. 3A and a stirring screw 126b shown in FIG. 3B.
  • the stirring mechanism 126 can cause the grinding medium 124b to flow by rotating the stirring impeller 126a or the stirring screw 126b generated by rotating the rotary shaft 126c, thereby grinding slag particles and the like.
  • the respective stirring impellers 126a have a direction substantially orthogonal to the depth direction (hereinafter simply referred to It is preferable to arrange in an inclined manner with respect to the horizontal direction.
  • the stirring impeller 126a may be disposed only in one stage as shown in FIG. 3A, or may be disposed as a plurality of stages so that the grinding media 124b can be stirred at different depths in the grinding container 122.
  • the rotary shaft 126c may extend from the liquid surface side of the crushing container 122 toward the bottom surface side, or extends from the bottom surface side of the crushing container 122 toward the liquid surface side. You may leave it.
  • the grinding media 124a and the grinding media 124b may be of any material and size capable of grinding slag particles and the like, and known balls used in a ball mill and known beads used in a bead mill can be used.
  • the carbon dioxide introducing unit 130 introduces carbon dioxide supplied from an external carbon dioxide supply source into the slurry.
  • the carbon dioxide introducing unit 130 may introduce carbon dioxide into the slurry in any of the elution / settling tank 110 (see FIG. 1), the slurry channel 142, the pulverizing unit 120, and the slurry channel 144.
  • the carbon dioxide introducing unit 130 introduces a sufficient amount of carbon dioxide into a slurry containing steelmaking slag in which a new surface is formed by grinding and the like, and calcium is easily eluted to lower the carbon dioxide concentration.
  • the carbon dioxide introducing unit 130 has a bubble refining device 131 for refining bubbles of carbon dioxide at the inlet of carbon dioxide to the elution / settling tank 110.
  • the bubble refining device 131 is an aeration tube having a plurality of fine holes, and the fine holes of carbon dioxide introduced into the elution / settling tank 110 from the fine holes.
  • a well-known micro bubble generator etc. can be used besides the aeration tube.
  • a bubble refinement device 131 may be arranged.
  • carbon dioxide When carbon dioxide is introduced into the slurry in the slurry flow channel 144, it is preferable to introduce carbon dioxide in the vicinity of the grinding unit 120 and between the grinding unit 120 and the elution / settling tank 110.
  • carbon dioxide When introducing carbon dioxide into the slurry in the elution / settling tank 110, from the viewpoint of increasing the amount of carbon dioxide dissolved in the slurry, introduce carbon dioxide into the area on the bottom side of the elution / settling tank where the pressure increases. Is preferred. Further, from the viewpoint of preventing re-floating of the precipitated slag, it is preferable to introduce carbon dioxide at a position above the deposited slag.
  • carbon dioxide When carbon dioxide is introduced into the slurry in the pulverizing unit 120, carbon dioxide can be introduced into the slurry, for example, from the stirring mechanism 126 disposed inside the pulverizing unit 120b shown in FIG. 2B.
  • the slurry channel 140 takes out from the slurry outlet 112 of the elution / settling tank 110 the slurry whose concentration of steelmaking slag has been increased by sedimentation of the steelmaking slag, and introduces it into the grinding unit 120; And a slurry flow path 144 for reintroducing the slurry containing the steelmaking slag ground or the like at 120 into the elution / settling tank 110.
  • the slurry flow path 142 may have a flow path diameter which can take out the slurry in which the concentration of the steelmaking slag has been increased by the pump 146 or the like from the slurry outlet 112 of the elution / settling tank and circulate it.
  • the flow rate of the slurry in the slurry flow channel 142 may be slow (the flow rate may be small), and the steelmaking slag that has settled to the slurry outlet 112 may be deposited (see FIG. 5A).
  • the slurry channel 144 reintroduces the slurry containing the steelmaking slag pulverized or the like by the pulverizing unit 120 into the elution / settling tank 110.
  • the slurry channel 144 is installed so that the slurry re-introduction port 114 is disposed at a position lower than the liquid surface of the elution / settling tank 110 by 0.1 m or more, preferably 0.2 m or more, more preferably 0.3 m or more. Is preferred.
  • carbon dioxide is introduced to the slurry in the pulverizing unit 120 or the slurry flow channel 144 (see FIG.
  • the slurry flow channel 144 has a height from the deepest portion of the elution / settling tank 110 to the liquid surface.
  • the slurry re-introduction port 114 is disposed at a position deeper than a half height.
  • FIGS. 1 to 5 the configuration of the device shown in FIGS. 1 to 5 is merely an example, and various modifications and arbitrary combinations of the configurations shown in the respective drawings are possible within the scope of the spirit of the present invention. It's too late.
  • the elution / settling tank 110 may have a bottom impeller 116 for stirring the slurry in the vicinity of the bottom surface to facilitate removal of the steelmaking slag deposited on the bottom surface.
  • the elution / settling tank 110 has a bottom proximity impeller 118 which rotates along the bottom close to the bottom to scrape out the steelmaking slag deposited on the bottom and to be taken out easily. Good.
  • the rotation speed of the bottom impeller 116 and the bottom proximity impeller 118 is preferably as slow as not to prevent the sedimentation of the steelmaking slag on the upper side, and can be, for example, 30 rpm or less, preferably 10 rpm or less.
  • bottom surface impeller 116 and bottom surface proximity impeller 118 are disposed through the slurry flow channel 142 so that steel slag deposited on the bottom surface can be easily removed even if the elution / settling tank 110 is enlarged. It is preferable that the rotary shaft 119 be supported from the bottom side of the elution / settling tank 110 and operated. Moreover, it is preferable that these bottom surface impeller 116 and the bottom surface proximity impeller 118 be disposed only on the bottom surface of the elution / settling tank 110 so as not to prevent the sedimentation of the steelmaking slag on the upper side.
  • the grinding unit 120 may be in any of the modes shown in FIGS. 2A and 2B, etc., and the carbon dioxide introduction unit 130 is an elution / settling tank 110 (see FIG. 1), a slurry flow Carbon dioxide may be introduced to the slurry in any of the passage 142, the grinding unit 120 and the slurry passage 144 (see FIG. 4).
  • the steelmaking slag deposited on the bottom surface is less likely to move to the slurry outlet 112, as shown in FIG.
  • the effect of the steelmaking slag removing mechanism for moving the steelmaking slag deposited on the bottom surface to the slurry outlet 112 as shown in FIG. 7 is remarkable.
  • the steelmaking slag removal mechanism is not limited to the bottom surface impeller shown in FIG. 6 and the bottom surface close impeller shown in FIG. 7, but may be a wiper, scraper, scraper or the like or a mechanism for vibrating the bottom surface.
  • the amount of Ca compound eluted from steelmaking slag when compared under the same conditions (water / slag ratio etc.) other than the Ca elution method Is expected to increase the recovery of calcium from steelmaking slag.
  • the steelmaking slag is subjected to hydration treatment before calcium is eluted according to the first embodiment described above.
  • FIG. 8 is a flow chart showing an exemplary process of the method of eluting calcium from steelmaking slag according to the present embodiment.
  • the steelmaking slag is subjected to a hydration treatment (step S110), and thereafter, calcium is eluted from the steelmaking slag according to the first embodiment described above (step S130).
  • calcium in steelmaking slag is 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 compound such as iron aluminum (Ca 2 (Al 1 -x Fe x ) 2 O 5 ).
  • Ca hydrate formed by the above reaction and the like is easily dissolved in a CO 2 aqueous solution. Therefore, the hydration treatment makes it easier to elute calcium derived from calcium silicate and calcium iron oxide aluminum etc. contained in steelmaking slag.
  • free lime is easily dissolved in a CO 2 aqueous solution, it is generally contained in the steelmaking slag only at less than about 10% by mass.
  • calcium silicate is generally contained in about 25% by mass to 70% by mass in steelmaking slag, and calcium iron aluminum is usually contained in about 2% by mass to about 30% by mass in steelmaking slag. Therefore, if calcium contained in calcium silicate and calcium iron oxide is easily eluted by CO 2 aqueous solution by hydration treatment, the elution amount of calcium from steelmaking slag to CO 2 aqueous solution can be increased. It will also be possible to recover calcium from slag in a shorter time.
  • the sum of the volumes of compounds produced by the hydration treatment will usually be greater than the sum of the volumes of the compounds prior to reaction. Furthermore, during the hydration process, part of the free lime in the steelmaking slag elutes into the water for treatment. Therefore, when the hydration treatment is performed, a crack is generated inside the slag particle, and the slag particle is easily broken starting from the crack. Thus, when the slag particles are disintegrated, the particle diameter of the slag particles is reduced, the surface area per volume is increased, and the water or the CO 2 aqueous solution can sufficiently penetrate to the inside of the steelmaking slag. Many Ca compounds can be hydrated in step S110), and more calcium can be eluted in the calcium elution step (step S130).
  • the hydration treatment may be performed by a method and conditions under which the Ca compound, preferably calcium silicate or calcium iron aluminum oxide, contained in the steelmaking slag can be hydrated.
  • the Ca compound preferably calcium silicate or calcium iron aluminum oxide
  • a treatment for settling steelmaking slag immersed in water and settled (hereinafter, also simply referred to as “immersion and standing”), stirring or crushing steelmaking slag immersed in water, etc.
  • Treatment (hereinafter, also simply referred to as “immersion and agitation, etc.”), treatment of leaving a paste containing water and slag particles (hereinafter, also simply referred to as “pasted and settled”), and a sufficient amount of water vapor
  • the processing hereinafter, also simply referred to as "wet and stand” or the like in which the steelmaking slag is allowed to stand is included in the container having the same. According to these methods, steelmaking slag and water can be brought into sufficient contact.
  • the hydration treatment only one of the above-mentioned immersion and standing, immersion and stirring, pastelization and wet and standing, etc. may be applied, or two or more of these may be carried out in any order. .
  • the hydration treatment by immersion stirring or the like is preferable from the viewpoint of making the calcium more easily eluted by performing the hydration treatment sufficiently to the inside of the slag particles.
  • Immersion stirring etc. may stir steelmaking slag soaked in water in the inside of a container having a stirring impeller, or stir steelmaking slag in an elution / settling tank or a ball mill usable in the first embodiment described above. It may be crushed while doing so. From the viewpoint of facilitating the elution of calcium more easily by the hydration treatment to the inside of the slag particles, it is preferable to immerse and stir the steelmaking slag while stirring the steelmaking slag.
  • the reaction by the above-mentioned hydration treatment occurs due to the contact of the Ca compound and water near or inside the surface of the steelmaking slag.
  • the amount of contact with water is larger in the vicinity of the surface. Therefore, Ca hydrate is more likely to be generated near the surface of steelmaking slag.
  • the components contained in steelmaking slag are dissolved in water used for hydration treatment, Fe, Al, Si and Mn or their hydroxides, carbonates, and oxides are dissolved as in the above-mentioned dissolution in CO 2 aqueous solution. Hydrates may remain or precipitate on the surface of steelmaking slag. When these remaining or precipitated substances inhibit the penetration of water into the inside of the steelmaking slag, Ca hydrate is less likely to be formed inside the steelmaking slag.
  • the surface area of the slag particles is increased by crushing the steelmaking slag immersed in water during the hydration treatment, and the contact area between water and the slag particles is further increased.
  • a new surface where the above-mentioned substance has not yet remained or precipitated is continuously formed, and water is continuously formed from the continuously formed surface to the inside of steelmaking slag.
  • the Ca hydrate is more likely to be formed inside the steelmaking slag.
  • the above-mentioned remaining or precipitated substances are removed, the contact area between water and slag particles becomes larger, and water is more likely to penetrate inside steelmaking slag. Become.
  • the hydration treatment may be performed by a processing apparatus different from the elution / settling tank used in the first embodiment, but from the viewpoint of simplifying the process, the elution / settling tank used in the first embodiment Hydration treatment by immersion and standing or immersion stirring in an internal or other wet grinding apparatus, for example, hydration treatment by immersion stirring in an elution / settling tank or other wet grinding apparatus used in the first embodiment You may At this time, if processing similar to that of the first embodiment or processing similar to pulverization by a common other wet pulverizing apparatus is performed except that carbon dioxide is introduced, hydration processing such as immersion stirring can be performed.
  • the above-mentioned hydration treatment by immersion stirring and the like and the elution of calcium according to the first embodiment are discharged from the slurry / settling tank and re-introduced to the elution / settling tank. Since it becomes unnecessary to move the slurry etc. without putting in between, hydration and elution of calcium can be performed more easily.
  • the water used for the hydration treatment is non-ionized free carbon dioxide and ionized bicarbonate ions (HCO 3 ⁇ ) etc.
  • the content of carbon is preferably less than 300 mg / L. If the content of carbon dioxide is less than 300 mg / L, it is difficult to elute calcium compounds other than free lime and calcium hydroxide in water used for hydration treatment, so most of the calcium contained in steelmaking slag is calcium It can be eluted in a CO 2 aqueous solution in the elution step, and the calcium recovery step is less likely to be complicated.
  • the temperature of water used for the hydration treatment may be a temperature at which the water does not evaporate violently.
  • the temperature of water is preferably 100 ° C. or less.
  • the temperature of the water may be 100 ° C. or higher as long as it is equal to or lower than the boiling point of water at the pressure when the hydration treatment is performed. .
  • the temperature of the water when the hydration treatment is performed by immersion and standing or immersion stirring is 0 ° C.
  • the upper limit of the temperature is not particularly limited, but in view of the pressure resistance of the apparatus and the economical aspect, 300 ° C. or less is preferable. Moreover, it is preferable that the temperature at the time of giving a hydration process by paste formation stationary is 0 degreeC or more and 70 degrees C or less.
  • the duration of the hydration treatment can be optionally set depending on the average particle diameter of the slag and the temperature (the temperature of the air containing water or water vapor) for the hydration treatment.
  • 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 at which the hydration treatment is performed is higher.
  • the duration of the hydration treatment should be about 8 hours continuously. And preferably 3 hours to 30 hours.
  • the duration of the hydration treatment is preferably continuously 0.6 hours or more and 8 hours or less.
  • the duration of the hydration treatment is continuously 0.1 hour or more It is preferable to set it as 5 hours or less, and it is more preferable to set it as 0.2 hours or more and 3 hours or less.
  • the duration of the hydration treatment is such that the maximum particle diameter of the slag particles is 1000 ⁇ m or less, preferably 500 ⁇ m or less, more preferably 250 ⁇ m, more preferably It is preferable to carry out until 100 ⁇ m or less.
  • the hydration treatment is preferably carried out to such an extent that calcium silicate is sufficiently hydrated and calcium hydroxide, or calcium iron oxide is sufficiently hydrated to be calcium oxide-based.
  • the hydration treatment is preferably performed until the amount of calcium silicate contained in the steelmaking slag is 50% by mass or less, or the amount of calcium iron aluminum oxide is 20% by mass or less.
  • the Ca compound contained in the steelmaking slag in particular calcium silicate and calcium iron oxide, is hydrated to be Ca hydrate which is more easily eluted in the CO 2 aqueous solution. Because it is possible, more calcium can be eluted into the aqueous solution of CO 2 in a shorter time. In addition, the hydration process in the second embodiment can be easily performed, so the burden of costs at the time of implementation is small.
  • the steelmaking slag is subjected to magnetic separation before the calcium is eluted according to the first embodiment described above.
  • FIG. 9 is a flow chart showing an exemplary process of the method of eluting calcium from steelmaking slag according to the present embodiment.
  • the steelmaking slag is subjected to magnetic separation (step S120), and thereafter, calcium is eluted from the steelmaking slag according to the first embodiment described above (step S130).
  • Magnetic separation can be performed using a known magnetic separator.
  • the magnetic separator may be either dry or wet, and can be selected according to the state of the steelmaking slag (whether dry or slurry).
  • the magnetic separator can be appropriately selected from a drum type, a belt type, a flow type between fixed magnets, etc. 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 separator may be a permanent magnet or an electromagnet.
  • the magnetic flux density by the magnet may be such that it can selectively capture iron-based compounds and metallic iron from other compounds contained in steelmaking slag, and can be, for example, 0.003 T or more and 0.5 T or less, 0 It is preferable to set it to .005T or more and 0.3T or less, and it is more preferable to set it to 0.01T or more and 0.15T or less.
  • magnetic separation does not have to be applied until all of the iron-based compounds contained in the steelmaking slag are removed. Even if the amount of the iron-based compound removed from the steelmaking slag by magnetic separation is small, the effect of the present invention is exhibited that calcium is more easily eluted in the aqueous CO 2 solution than in the prior art. Therefore, the time and the number of times of magnetic separation may be selected appropriately according to the influence of the magnetic selection on the manufacturing cost.
  • the steelmaking slag is heat-treated, the magnetization of the iron-based compound and the metallic iron is increased, and a larger amount of iron-based compound can be removed by magnetic separation.
  • the 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.
  • a slurry dispersed in water since the slag particles are easily dispersed due to the polarity of water molecules, water flow and the like, it is easy to selectively capture the iron-based compound and the metallic iron by the magnetic force.
  • the slag particles when the particle size of the slag particles is 1000 ⁇ m or less, in a gas such as air, the slag particles are caused by the liquid cross-linking ability by condensation of water vapor in the atmosphere, the van der Waals force between the slag particles, the electrostatic force between the slag particles Although they tend to aggregate, the slurry particles can sufficiently disperse the slag particles.
  • metallic iron in steelmaking slag is minute, it is difficult to capture it when the steelmaking slag is dry, but when the steelmaking slag is made slurry, metallic iron dispersed in water also becomes easy to be trapped by magnetic separation.
  • the slurry after removing the iron-based compound and metallic iron by magnetic separation may be used as it is for elution of calcium according to the first embodiment, but when the steelmaking slag is in a slurry form, solid-liquid separation is performed to make the steelmaking slag. It is preferable to separate the liquid and the liquid component. Solid-liquid separation can be performed by known methods including vacuum filtration and pressure filtration.
  • the liquid component obtained by the above solid-liquid separation (hereinafter, also simply referred to as "magnetic water separation”) is alkaline because it contains calcium eluted from steelmaking slag in addition to water used for slurrying. Therefore, it is possible to use the liquid component to increase the pH of when precipitating calcium from CO 2 aqueous solution after elution of calcium in contact with later-described, steelmaking slag, CO 2 solution.
  • the magnetic separation removal slag removed from the steelmaking slag by magnetic separation contains a large amount of iron-based compounds and compounds containing Fe such as metallic iron as described above, it can be reused as a raw material for blast furnace and sintering.
  • either one or both may be performed.
  • either of the hydration treatment and the magnetic separation may be performed first, or both of the wet magnetic separation and the wet magnetic separation may be simultaneously performed.
  • hydration treatment in particular, hydration treatment by immersion stirring
  • magnetic separation is performed, whereby the recovery rate of calcium is further increased, particularly when the device is enlarged.
  • the whole processing can be performed in a shorter time.
  • the compound containing iron remaining or precipitated on the surface of steelmaking slag inhibits the contact between the above-mentioned CO 2 aqueous solution and the surface of steelmaking slag, and the compound containing iron having a relatively high hardness It is considered that the inhibition of the grinding or grinding due to the above can be suppressed, and the Ca in the steelmaking slag can be easily eluted by the aqueous solution of CO 2 .
  • calcium iron aluminum contained in steelmaking slag is difficult to be magnetized after Ca is eluted by contact with a CO 2 aqueous solution, and recovery by magnetic separation is not easy.
  • calcium iron aluminum oxide in steelmaking slag can also be recovered by performing magnetic separation prior to contact with a CO 2 aqueous solution, and iron derived from calcium iron aluminum can also be reused more easily.
  • FIG. 10 is a flow chart of a method of recovering calcium from steelmaking slag according to the present invention. As shown in FIG. 10, the method includes the steps of eluting calcium (step S100) and recovering calcium (step S200).
  • Step S100 In the step of eluting calcium (step S100), calcium is eluted from steelmaking slag.
  • the elution of calcium may be carried out by the methods described as the first to third embodiments described above.
  • step S200 recovery of calcium (step S200) may be performed in the elution / settling tank where the elution of calcium has been performed unless it becomes difficult.
  • FIG. 11 is a flowchart showing an example of the step of recovering calcium (step S200).
  • step S200 for example, the step of separating steelmaking slag and a CO 2 aqueous solution (step S210: hereinafter, also referred to as “separation step”), calcium is precipitated.
  • step S220 hereinafter, also referred to as "precipitation step”
  • step S230 a step of recovering the precipitated solid component
  • a CO 2 aqueous solution in which calcium is dissolved is separated from steelmaking slag (step S210).
  • the separation can be carried out by known methods. Examples of separation methods include filtration and methods in which a CO 2 aqueous solution is allowed to settle to precipitate steelmaking slag.
  • separation methods include filtration and methods in which a CO 2 aqueous solution is allowed to settle to precipitate steelmaking slag.
  • the supernatant liquid may be further recovered, or in the two-component system including the supernatant liquid and the precipitated steelmaking slag unless the solid component deposited in the later step is mixed with the steelmaking slag.
  • the subsequent steps may be performed only on the supernatant fluid.
  • step S220 calcium eluted in a CO 2 aqueous solution is precipitated as a solid component containing calcium.
  • Calcium eluted in a CO 2 aqueous solution can be precipitated by a known method.
  • Examples of the method of precipitating calcium eluted in a CO 2 aqueous solution as a solid component include a method of removing carbon dioxide from a CO 2 aqueous solution and a method of raising the pH of the CO 2 aqueous solution.
  • ⁇ Removal of carbon dioxide> carbon dioxide can be removed from the CO 2 aqueous solution separated from the steelmaking slag in the separation step (step S210), and calcium eluted in the CO 2 aqueous solution can be precipitated in the step of eluting calcium (step S100).
  • the Ca compound precipitated at this time include calcium carbonate, calcium carbonate hydrate and calcium hydroxide.
  • the method for removing carbon dioxide from the CO 2 aqueous solution is not particularly limited.
  • methods of removing carbon dioxide include (1) gas introduction, (2) vacuum and (3) heating.
  • the gas to be introduced may be a gas that reacts with water (chlorine gas, sulfur dioxide gas, etc.), but the calcium formed by the ions formed by introducing it into the CO 2 aqueous solution and the calcium dissolved in water forms a salt. From the viewpoint of suppressing a decrease in the amount of precipitation, it is preferable that the gas has low reactivity with water.
  • the gas introduced into the CO 2 aqueous solution may be an inorganic gas or an organic gas.
  • inorganic gases are more preferable because they have less possibility of combustion or explosion even if they leak to the outside.
  • inorganic gases having low reactivity with water include air, nitrogen, oxygen, hydrogen, argon and helium and mixed gases thereof.
  • the mixed gas includes the air of the environment in which the present process is performed, which contains nitrogen and oxygen in a ratio of approximately 4: 1.
  • Examples of organic gases having low reactivity with water include methane, ethane, ethylene, acetylene, propane and fluorocarbons.
  • the above (1) to (3) may be combined.
  • what is necessary is just to select the optimal combination in consideration of the supply system of gas or heat, a location, utilization of by-product gas in a factory, etc. of these combinations.
  • the effect and removal effect of carbon dioxide removal by the introduction of the gas, and the reduced pressure of the aqueous solution of CO 2 The effect of removing carbon dioxide can be obtained, and carbon dioxide can be removed efficiently. At this time, further heating further promotes the effect of removing carbon dioxide. At this time, the additive effect of the decompression effect as CO 2 aqueous solution introduced into the CO 2 aqueous solution of the gas, for the carbon dioxide can be easily removed, it is not necessary to raise the heating temperature, The heating cost can be reduced.
  • step S210 When calcium starts to precipitate, turbidity due to calcium carbonate is generated in the aqueous solution of CO 2 . It is sufficient if the pH of the aqueous solution of CO 2 is raised to such an extent that this cloudiness can be confirmed visually. From the viewpoint of more fully depositing calcium and increasing the recovery rate of calcium, raising the pH by 0.2 or more with respect to the pH of the CO 2 aqueous solution separated from the steelmaking slag in the separation step (step S210) Preferably, it is more preferably 0.3 or more, more preferably 1.0 or more, still more preferably 1.5 or more, and even more preferably 2.0 or more.
  • the pH of the CO 2 aqueous solution can be measured by a known glass electrode method.
  • step S230 solid components containing not only calcium but also other elements such as phosphorus are precipitated in this step, according to the present inventor's knowledge, solid components which precipitate immediately after starting to raise the pH (hereinafter referred to simply as “initial precipitation
  • the content of the phosphorus-containing compound (hereinafter, also simply referred to as “phosphorus compound”) is higher, and the later precipitated solid component (hereinafter, also simply referred to as “late precipitate”) has a higher content ratio. Lower phosphorus content ratio. Therefore, the step of recovering (step S230) to be described later is performed while raising the pH, and the initial precipitate is recovered to separate the solid component having a higher ratio of phosphorus and the solid component having a lower ratio of phosphorus. Can be collected.
  • Phosphorus compounds recovered from steelmaking slag can be reused as phosphorus resources. Therefore, when the solid component having a high content of phosphorus compound is recovered, reuse of phosphorus is facilitated. Moreover, although Ca compound collect
  • the initial precipitate may be recovered before the pH rises by 1.0.
  • PH of CO 2 aqueous solution for example, by introducing an alkaline substance into CO 2 aqueous solution, can be increased.
  • alkaline substances that can be introduced into the aqueous CO 2 solution include calcium hydroxide, ammonia and sodium hydroxide.
  • calcium hydroxide, ammonia or sodium hydroxide When calcium hydroxide, ammonia or sodium hydroxide is introduced, a solution of these substances in water may be added to the aqueous CO 2 solution.
  • Calcium hydroxide, ammonia and sodium hydroxide may be commercially available, or may be contained in waste liquid or other liquid. When calcium hydroxide in waste liquid is charged, for example, the waste liquid produced in the reaction of calcium carbide (calcium carbide) with water to produce acetylene can be added to the aqueous CO 2 solution.
  • slag leaching water prepared by immersing steelmaking slag in water, the above-mentioned magnetic separated water or the above-mentioned hydration treated water may be introduced into the above-mentioned CO 2 aqueous solution.
  • Slag leachate, magnetic separation water and hydration treated water may be obtained by immersion in water, magnetic separation or hydration treatment of steelmaking slag from which calcium is to be recovered, or water of another steelmaking slag. It may be obtained by immersion, magnetic separation or hydration treatment.
  • alkaline substances it is preferable to use calcium hydroxide, calcium hydroxide-based waste solution, slag leachate, magnetic separation water, hydration treated water.
  • the CO 2 aqueous solution after calcium recovery by the method according to the present embodiment can simplify or eliminate the waste water treatment, thereby suppressing the cost of the waste water treatment.
  • the aqueous solution of CO 2 after recovery of calcium contains almost no metal element such as Ca, Fe, Mn, Al, P and CO 2 , it can be reused in the process, enabling waste water elimination obtain.
  • the removal of carbon dioxide and the increase in pH may be performed in combination.
  • the solid component precipitated in the precipitation step (step S220) is recovered (step S230).
  • the precipitated solid component can be recovered by known methods including vacuum filtration and pressure filtration.
  • This solid component includes calcium derived from steelmaking slag.
  • the steelmaking slag shown in Table 1 was crushed to a diameter of 5 mm or less, and then heated at 750 ° C. for 40 minutes. After heating, it was air cooled to normal temperature. Thereafter, the steelmaking slag was further crushed, and the one using a sieve having an aperture of 106 ⁇ m was used for the subsequent treatment.
  • Magnetic selection Water was added to the hydrated slurry-like steelmaking slag to make the total amount of water in the slurry 12.5 L.
  • the slurry was charged into a drum-type magnetic separator, and magnetic selection was performed under the conditions of a maximum magnetic flux density of 0.07 T on the drum surface and a drum peripheral velocity of 5 m / min.
  • the concentration of iron in the steelmaking slag after being magnetically selected was measured by chemical analysis, and it was found that 40% by mass of the iron element contained in the first steelmaking slag was removed.
  • the elution / settling tank had a cylindrical shape with an inner diameter of 180 mm, and an impeller rotating near the bottom along the bottom was installed on the bottom so that the deposited steelmaking slag moved to the suction port. The impeller was rotated at 5 rpm. The slurry remaining in the magnetic separation step or the slurry not subjected to magnetic separation was charged into the elution / settling tank, and water was added so that the total amount of water in the slurry was 50 liters. For crushing and the like, a continuous crushing unit shown in FIG. 2A was used.
  • This crushing part was a horizontal cylindrical shape with an inner diameter of 100 mm, and a ball of ⁇ 10 mm was placed therein at 75% of the total volume. At the same time, 15 L / min of carbon dioxide was introduced into the slurry inside the elution / settling tank.
  • the above-described hydrated steelmaking slag is added to this ball mill, and water is added so that the total amount of water is 30 L, and then the ball mill is rotated at 30 rpm to make the rotating ball and steelmaking slag contact to grind the steelmaking slag. It was equal.
  • carbon dioxide in an amount of 9 L / min was introduced into the slurry in which steelmaking slag was suspended in water.
  • Table 2 shows the calcium elution rate (Ca elution rate) when the above hydration and magnetic separation were performed.
  • the method of calculating the dissolution rate was as follows. After performing any of the above Ca elution-1 to Ca elution-2 treatment for 30 minutes, the slurry is filtered to separate the aqueous solution of CO 2 in the slurry, and the calcium concentration in the aqueous solution of CO 2 is measured by the chemical analysis method did.
  • the elution amount was calculated from the measured calcium concentration in the CO 2 aqueous solution, and was divided by the calcium amount of the slag brought into the Ca elution step to calculate the elution rate of calcium into the CO 2 aqueous solution.
  • the steelmaking slag contained in the slurry is made to settle inside the elution / settling tank, the slurry whose concentration is increased is taken out from the elution / settling tank, and after the steelmaking slag is crushed in the grinding section, the elution / settling tank Test No. reintroduced into Test No. 1 to 3 were made by contacting steelmaking slag and CO 2 aqueous solution by other methods.
  • the elution rate of Ca was higher than 4 to 5.
  • the method for eluting calcium according to the present invention is useful as a method for recovering calcium resources in steelmaking because it can easily increase the elution amount of calcium in steelmaking slag to an aqueous solution containing carbon dioxide.
  • Apparatus for eluting calcium from steelmaking slag 110 elution / settling tank 112 slurry outlet 114 slurry re-introduction port 116 bottom impeller 118 bottom surface close impeller 119 rotating rod 120, 120a, 120b grinding part 122a, 122b grinding container 124a, 124b grinding medium 126 stirring mechanism 130 carbon dioxide introduction part 131 bubble refinement device 140, 142, 144 slurry flow path 146 pump

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Abstract

L'invention a pour objet de fournir un procédé d'élution de calcium à partir de scories d'élaboration d'acier qui permet une élution facile d'une grande quantité de calcium à partir de scories d'élaboration d'acier vers une solution aqueuse contenant un dioxyde de carbone. À cet effet, l'invention concerne un procédé d'élution de calcium à partir de scories d'élaboration d'acier. Selon ce procédé, les scories d'élaboration d'acier contenues dans une bouillie à teneur en scories d'élaboration d'acier et dans laquelle un dioxyde de carbone est introduit sont soumises à une décantation dans la partie interne d'une cuve d'élution / décantation, la concentration en scories d'élaboration d'acier dans ladite bouillie est augmentée, et la bouillie dont la concentration en scories d'élaboration d'acier est ainsi augmentée, est extraite de ladite cuve d'élution / décantation. Les scories d'élaboration d'acier contenues dans ladite bouillie ainsi extraite, sont pulvérisées, ou la surface des scories d'élaboration d'acier contenues dans ladite bouillie ainsi extraite, est broyée. La bouillie contenue dans lesdites scories d'élaboration d'acier pulvérisées ou broyées sont introduites dans ladite cuve d'élution / décantation.
PCT/JP2018/041634 2017-11-30 2018-11-09 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 Ceased WO2019107116A1 (fr)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112547046A (zh) * 2020-11-23 2021-03-26 安徽元琛环保科技股份有限公司 一种基于钒钛渣的环保型脱硝催化剂的制备方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100998916B1 (ko) * 2010-05-14 2010-12-15 주식회사 케이비알에너지텍 탄산가스를 활용한 고순도 탄산칼슘의 제조방법
JP2011093761A (ja) * 2009-10-30 2011-05-12 Jfe Steel Corp 硫黄・Ｃａ含有スラグの処理方法
JP2013142046A (ja) * 2012-01-10 2013-07-22 Nippon Steel & Sumitomo Metal Corp 鉱さい燐酸肥料用原料回収方法
WO2017163595A1 (fr) * 2016-03-24 2017-09-28 日新製鋼株式会社 Procédé d'élution de calcium à partir de scories d'acier et procédé de récupération de calcium à partir de scories d'acier

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011093761A (ja) * 2009-10-30 2011-05-12 Jfe Steel Corp 硫黄・Ｃａ含有スラグの処理方法
KR100998916B1 (ko) * 2010-05-14 2010-12-15 주식회사 케이비알에너지텍 탄산가스를 활용한 고순도 탄산칼슘의 제조방법
JP2013142046A (ja) * 2012-01-10 2013-07-22 Nippon Steel & Sumitomo Metal Corp 鉱さい燐酸肥料用原料回収方法
WO2017163595A1 (fr) * 2016-03-24 2017-09-28 日新製鋼株式会社 Procédé d'élution de calcium à partir de scories d'acier et procédé de récupération de calcium à partir de scories d'acier

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112547046A (zh) * 2020-11-23 2021-03-26 安徽元琛环保科技股份有限公司 一种基于钒钛渣的环保型脱硝催化剂的制备方法

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