WO2019107115A1 - 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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WO2019107115A1
WO2019107115A1 PCT/JP2018/041632 JP2018041632W WO2019107115A1 WO 2019107115 A1 WO2019107115 A1 WO 2019107115A1 JP 2018041632 W JP2018041632 W JP 2018041632W WO 2019107115 A1 WO2019107115 A1 WO 2019107115A1
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steelmaking slag
calcium
grinding
slurry
carbon dioxide
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PCT/JP2018/041632
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English (en)
Japanese (ja)
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康 福居
昭広 浅場
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日新製鋼株式会社
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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
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/20—Treatment of water, waste water, or sewage by degassing, i.e. liberation of dissolved gases
    • 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.
  • Ca 2 (Al 1 -x Fe x ) 2 O 5 calcium iron oxide (Ca 2 (Al 1 -x Fe x ) 2 O 5 ) or the like (hereinafter referred to collectively as "Ca compound, generically containing compounds containing the above-mentioned calcium present in steelmaking slag It is also called ").
  • 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 suppresses the stirring of the slurry containing steelmaking slag in the region on the upper side close to the liquid surface inside the crushing and settling tank while settling the steelmaking slag, while suppressing the stirring of the steelmaking slag.
  • 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 grinding / settling tank into which a slurry containing steelmaking slag is charged, and an area on the bottom side inside the grinding / settling tank, and an upper portion close to a liquid surface inside the grinding / settling tank
  • the present invention relates to an apparatus for eluting calcium from steelmaking slag, including a carbon dioxide introduction unit for introducing carbon dioxide into the slurry simultaneously with grinding or grinding by the grinding mechanism.
  • 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 stirring impeller of a stirring mechanism of an apparatus used for eluting calcium from steelmaking slag
  • FIG. 2B is a diagram of an apparatus used for eluting calcium from steelmaking slag It is a schematic diagram which shows the exemplary form of the stirring screw which a stirring mechanism has.
  • FIG. 3 is a schematic view showing the configuration of another apparatus used to elute calcium from steelmaking slag in the first embodiment of the present invention.
  • 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 stirring impeller of a stirring mechanism of an apparatus used for eluting calcium from steelmaking slag
  • FIG. 2B is a diagram
  • 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. 5 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. 6 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. 7 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. 8 is a flow chart of a method of recovering calcium from steelmaking slag according to the present invention.
  • FIG. 9 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. 10 is a graph showing the relationship between the proportion of each carbonic acid species 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 flowing the particles of interest does not provide enough energy to destroy the particles of interest and reduce their size, as the particles of interest only move with the flow of the slurry.
  • 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.
  • the grinding and the like can be efficiently performed in a state where the concentration of the steelmaking slag is high.
  • grains in a slurry are easy to settle, so that a particle size is large. Therefore, in the method of the present embodiment, since the particle diameter 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 aqueous solution of CO 2 into the inside are difficult to occur are precipitated and crushed and crushed. It moves to the area on the bottom side of the tank, is crushed and the like, and contact with the CO 2 aqueous solution efficiently forms a new surface on which calcium is easily eluted. The slag particles whose particle size has become smaller due to pulverization and the like tend to float and move in the liquid surface direction (upper direction) of the pulverization / settling tank.
  • the above-mentioned pulverization and the like are performed only in the area on the bottom side of the pulverization / settling tank. Therefore, in the area on the upper side of the crushing and settling tank, the stirring of the slurry is suppressed, and the flow rate of the slurry is significantly slower than the area on the bottom side. That is, in the area
  • the concentration of steelmaking slag in the slurry becomes high (the concentration of water in the slurry becomes low) in the region on the bottom side of the crushing and settling tank, or the precipitated steelmaking slag accumulates in the region on the bottom side.
  • crushing etc. is performed in the area
  • the flow velocity of the slurry in the region on the bottom side where crushing of steelmaking slag is performed, it is preferable to set the flow velocity of the slurry to 1 m / min or more and 100 m / min or less, in order to efficiently crush steelmaking slag having a high concentration. It is more preferable to set at least 70 min / min.
  • the flow velocity of the slurry in the upper region where steelmaking slag is allowed to settle, is preferably 20 m / min or less, more preferably 10 m / min or less.
  • the lower limit of the flow velocity of the slurry in the upper side region is not particularly limited, it can be 0 m / min (static state).
  • the area on the upper side where crushing or the like of steelmaking slag is not performed preferably has a height of 0.2 m or more, and more preferably 0.3 m or more Preferably, it is more preferably 0.6 m or more.
  • the upper limit of the height of the upper region is not particularly limited, but may be 50.0 m.
  • 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, the slag particles which become smaller than a certain size and the CO 2 aqueous solution easily penetrates to the inside of the particles and which easily dissolves calcium are difficult to settle, so they are close to the liquid surface of the crushing and settling tank Easy to stay on the upper side.
  • 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.
  • 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 efficiency of pulverization and the like does not decrease even if the relative amount of water in the slurry is increased. Therefore, it is possible to increase the amount of water that is a saucer of eluted calcium in the slurry, and it is possible to dissolve much calcium.
  • 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 crushing of steelmaking slag in the crushing and 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 grinding / 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 simultaneously with or after the pulverization and the like.
  • Carbon dioxide can be introduced into the slurry, for example, by bubbling a gas containing carbon dioxide.
  • a bubble refining device such as a known aeration tube or micro bubble device at the outlet of gas to reduce the bubbles (bubbles) of carbon dioxide.
  • 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.
  • the apparatus 100 for eluting calcium from the steelmaking slag shown in FIG. 1 is contained in the above-mentioned slurry in the grinding / settling tank 110 into which the slurry (shaded area in the drawing) is charged, and the bottom side inside the grinding / settling tank 110. It has the grinding mechanism 120 which grinds a steelmaking slag etc., and the carbon-dioxide introduction
  • the grinding and settling tank 110 is a container into which the slurry is charged.
  • the grinding / settling tank 110 can accommodate the grinding mechanism 120 and the carbon dioxide introduction unit 130 inside the container, and if the size of the slag particles contained in the input slurry can be sufficiently ground by the grinding mechanism 120 Good.
  • the grinding / settling tank 110 may have a slurry inlet and a slurry outlet (both not shown).
  • the pulverizing mechanism 120 is disposed on the bottom side of the pulverizing / settling tank 110, and pulverizes slag particles in the slurry that has settled on the bottom side of the pulverizing / settling tank 110.
  • the grinding mechanism 120 constitutes a grinding area in the slurry.
  • the crushing mechanism 120 is preferably disposed at a position where the height (depth) of the slurry from the liquid surface when the slurry is introduced into the crushing and settling tank 110 is 0.2 m or more, and 0.3 m or more It is more preferable to arrange in the following position, and it is more preferable to arrange in the position which will be 0.6 m or more.
  • the upper limit of the height from the liquid surface of the slurry is not particularly limited, it can be 2.0 m.
  • the distance from at least the upper surface inside the grinding / settling tank 110 to the upper end of the grinding mechanism 120 may be in the above range.
  • the pulverizing mechanism 120 may have any configuration capable of pulverizing slag particles and the like so that stirring of the slurry is suppressed in the region on the upper side inside the pulverizing / settling tank 110 so that the steelmaking slag settles. It may be appropriately selected according to the size of the crushing and settling tank 110 and the like.
  • the grinding mechanism 120 can be configured to cause the grinding medium 122 introduced to the bottom side of the grinding / settling tank 110 to flow by the stirring mechanism 124.
  • the fluidized grinding medium 122 is in contact with the slag particles, and the fluidized and rotated grinding medium 122 slides the slag particles, and the slag particles are crushed more efficiently, etc. can do.
  • the grinding medium 122 may be of any material and size capable of grinding slag particles and the like, and known balls used for a ball mill, known beads used for a bead mill, etc. can be used.
  • the stirring mechanism 124 may be any mechanism as long as the grinding medium 122 can be made to flow and the slag particles can be crushed and the like.
  • the stirring mechanism 124 can be a plurality of stirring impellers 124 a shown in FIG. 2A and a stirring screw 124 b shown in FIG. 2B.
  • the stirring mechanism 124 can cause the grinding medium 122 to flow by the rotation of the stirring impeller 124a or the stirring screw 124b generated by rotating the rotating shaft 124c, and the slag particles can be crushed and the like.
  • each stirring impeller 124a has 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.
  • FIG. 1 shows a direction substantially orthogonal to the depth direction
  • stirring impeller 124a may be disposed only in one stage, or disposed as a plurality of stages so that grinding media 122 can flow at different depths in grinding / settling tank 110. It is also good.
  • the rotary shaft 124c may extend from the liquid surface side of the grinding / settling tank 110 toward the bottom side as shown in FIG. 1, or as shown in FIG. 3 and FIG. It may extend from the bottom side of the settling tank 110 toward the liquid surface side.
  • the pulverizing mechanism 120 has only one stirring mechanism 124, it has a plurality of stirring mechanisms 124 for flowing the grinding medium 122 at different places in the horizontal direction in the crushing / settling tank 110 or at different depths. You may
  • the carbon dioxide introduction unit 130 has a flow path 132 of carbon dioxide communicating the external carbon dioxide supply source with the inside of the grinding / settling tank 110 and an inlet 134 opened in the grinding / settling tank 110, The carbon dioxide flowing through the passage 132 is introduced into the slurry introduced into the crushing and settling tank 110 from the inlet 134.
  • the carbon dioxide introduction unit 130 simultaneously performs the introduction of carbon dioxide and the like by the crushing mechanism 120 and the like.
  • the inlet 134 is preferably arranged to have the same depth as the grinding mechanism 120 or a depth near that. More preferably, they are arranged at the same depth as the grinding mechanism 120. Since the introduced gaseous carbon dioxide is dissolved in the aqueous solution of CO 2 while moving in the liquid surface direction (upper side direction) of the slurry regardless of the position where the introduction port 134 is disposed, the pulverization / settling tank An elution region in which the slurry contacts with carbon dioxide can be formed on the grinding mechanism 110 and the upper side closer to the liquid surface.
  • the introduction port 134 is a diffusion tube which is a bubble refining device, and introduces the bubbles of the refined carbon dioxide into the inside of the crushing and settling tank 110.
  • the carbon dioxide introduction unit 130 has a single flow passage 132 and an introduction port 134, but the carbon dioxide introduction unit 130 may use carbon dioxide from a single flow passage or a plurality of different flow passages. There may be a plurality of inlets 134 of different horizontal positions or depths in the grinding and settling tank 110 introduced into the slurry.
  • the carbon dioxide introduction unit 130 may be configured to introduce carbon dioxide into the slurry from the stirring mechanism 124.
  • the carbon dioxide introducing unit 130 can introduce carbon dioxide to the same depth as the crushing mechanism 120, so steel making in the state in which calcium is most easily eluted immediately after being crushed etc. Calcium can be easily eluted from the slag.
  • FIG. 3 shows the configuration of an apparatus 200 used to elute calcium from steelmaking slag, having a carbon dioxide introduction unit 230 for introducing carbon dioxide into the slurry (shaded area in the drawing) from the stirring mechanism 224 of the grinding mechanism 220.
  • the stirring mechanism 224 causes the grinding medium 222 of the grinding mechanism 220 to flow by the rotation of the stirring impeller 224 a generated by rotating the hollow rotary shaft 224 c inside the grinding / settling tank 210 to grind the slag particles, etc. Can.
  • the hollow rotary shaft 224c simultaneously functions as the flow path 232 of the carbon dioxide introduction unit 230, and introduces carbon dioxide into the slurry from the carbon dioxide introduction port 234 provided at the tip.
  • the rotary shaft 224c may be provided with a plurality of openings, and carbon dioxide may be introduced into the slurry from the shaft portion other than the tip.
  • FIG. 4 shows another apparatus 300 used to elute calcium from steelmaking slag, having a carbon dioxide introduction unit 330 for introducing carbon dioxide into the slurry (the shaded area in the drawing) from the stirring mechanism 324 of the grinding mechanism 320.
  • the stirring mechanism 324 includes a hollow rotary shaft 324c, a hollow rod-like stirring rod support 324d extending horizontally from the rotary shaft 324c in the grinding / settling tank 310, and a grinding / settling tank from the stirring rod support 324d. It has a bar-like stirring rod 324 e extending in the depth direction of 310.
  • the hollow interior of the rotary shaft 324c and the hollow interior of the stirring rod support 324d are in fluid communication with each other, and the stirring rod support 324d is hollow interior and exterior And an inlet port 334 in fluid communication therewith.
  • the stirring mechanism 324 causes the grinding medium 322 of the grinding mechanism 320 to flow by the rotation of the stirring rod 324e generated by rotating the hollow rotary shaft 324c inside the grinding / settling tank 310, and the slag particles are ground. Etc.
  • the rotating shaft 324c and the stirring rod support 324d simultaneously function as the flow path 332 of the carbon dioxide introducing portion 330, and introduce carbon dioxide into the slurry from the introducing port 334 of the stirring rod support 324d.
  • carbon dioxide can be introduced into a wider range of the slurry introduced into the crushing and settling tank 310, and calcium is eluted from the crushed steel slag for a longer period of time. It can be made easy.
  • a plurality of openings may be provided in the tip of the rotary shaft 324c or in a shaft portion other than the tip, and carbon dioxide may be introduced into the slurry also from these openings.
  • the number of stir bar supports 324d extending from one rotary shaft 324c, the number of stir bars 324e extending from one stir bar support 324d, and the introduction of one stir bar support 324d is not particularly limited, and may be one or more, but from the viewpoint of enhancing the efficiency such as crushing or the ease of elution of calcium from the steelmaking slag, all may be more than one. Is preferred.
  • the stirring rod 324e may rotate itself. At this time, from the viewpoint of enhancing the efficiency such as grinding, when a plurality of stirring rods 324e extend from the stirring rod support 324d, one of the stirring rods 324d may rotate in a direction different from the other.
  • the stirring rod 324e may be configured to be extensible and contractible in the depth direction of the crushing and settling tank 310. At this time, from the viewpoint of enhancing the efficiency such as crushing, when a plurality of stirring rods 324e extend from the stirring rod support 324d, one of the stirring rods 324e may expand and contract in a cycle different from the others.
  • FIG. 5 is a schematic view showing a configuration of an apparatus 500 used for eluting calcium from steelmaking slag, in which a carbon dioxide introduction unit 530 is installed outside the crushing and settling tank.
  • the carbon dioxide introduction unit 530 has a circulation type flow path 535 and a pump 536 for taking out the slurry inside the pulverization / settling tank 510 and re-inflowing into the pulverization / settling tank 510. It has an inlet 534 for introducing carbon.
  • the outlet and re-inlet of the slurry from the grinding / settling tank 510 may have different heights, but preferably have the same height so as not to inhibit the sedimentation of the steelmaking slag.
  • the crushing mechanism 120 can be made into the structure similar to FIG. 1, detailed description is abbreviate
  • bubbles of carbon dioxide are refined by the shear force generated by the flow of steelmaking slag contained in the slurry, so the bubble refining device may not be disposed.
  • 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 carbon dioxide introduction portion has a hollow rotary shaft extending from the top side of the crushing / settling tank toward the bottom side, and the rotary shaft has its tip or hollow
  • the carbon dioxide may be introduced into the slurry from an opening that allows the inside and the outside of the shaft portion to flow.
  • the insides of the stirring impeller and the stirring screw as shown in FIG. 2A and FIG. 2B may be hollow so that carbon dioxide can be introduced into the slurry from the stirring impeller or the stirring screw.
  • the carbon dioxide introduction part is an opening that makes the inside of the stirring rod hollow as shown in FIG. 4 and allows the inside or the outside of the rod portion of the hollow stirring rod to flow. It is also possible to introduce carbon dioxide into the slurry. On the other hand, carbon dioxide may not be introduced into the slurry from the stirring rod support and the stirring rod shown in FIG. 4, and carbon dioxide may be introduced into the slurry only from the rotating shaft.
  • the carbon dioxide introducing unit is configured to introduce carbon dioxide from the separately provided flow path and inlet of carbon dioxide while introducing carbon dioxide from the stirring mechanism. It is also good.
  • carbon dioxide is not introduced from the rotating shaft shown in FIG. 3 or the rotating shaft, stirring rod support or stirring rod shown in FIG. It may be configured to introduce carbon.
  • carbon dioxide is introduced into the slurry inside the grinding / settling tank as in the apparatus shown in FIGS. 1, 3 and 4, and even outside the grinding / settling tank as in the apparatus shown in FIG. Carbon dioxide may be introduced into the slurry.
  • the number of stirring mechanisms is not particularly limited, and may be one or more.
  • the respective rotation shafts of the plurality of stirring mechanisms may rotate in the same direction, but in order to further increase the efficiency such as crushing, any rotation shaft The body may rotate in a different direction than the others.
  • 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. 6 is a flowchart showing an exemplary step 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 inside a container having a stirring impeller, or stir steelmaking slag in a crushing and 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 grinding / settling tank used in the first embodiment, but from the viewpoint of simplifying the process, the grinding / 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 a grinding / 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 grinding / settling tank and reloaded into the grinding / 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. 7 is a flow chart showing an exemplary process of the method for 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. 8 is a flow chart of a method of recovering calcium from steelmaking slag according to the present invention. As shown in FIG. 8, 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 a grinding / settling tank in which elution of calcium has been performed unless it becomes difficult.
  • FIG. 9 is a flow chart showing an example of the step of recovering calcium (step S200).
  • the step of recovering calcium (step S200) is, for example, a 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.
  • Example 1 The steelmaking slag which has a component ratio of Table 1 was prepared. In addition, the component of steelmaking slag was measured by the chemical analysis method. The steelmaking slag was pre-crushed and then passed through a sieve with an opening of 106 ⁇ m.
  • a part of the steelmaking slag shown in Table 1 was subjected to hydration treatment by the following method (hydration treatment-1). Thereafter, either the non-hydrated steelmaking slag or the above-mentioned hydrated steelmaking slag was brought into contact with the aqueous CO 2 solution by the following method (any of Ca elution-1 to Ca elution-3). Then, the elution rate of calcium to the CO 2 aqueous solution was measured.
  • any of the non-hydrated steelmaking slag and the above-mentioned hydrated steelmaking slag in the amounts shown in Table 2 is added, water is added so that the total amount of water is 30 L, and then the ball mill is The steelmaking slag was crushed by rotating the ball at 70 rpm and bringing the rotating ball into contact with the steelmaking slag. At the same time, carbon dioxide in an amount of 9 L / min was introduced into the slurry in which steelmaking slag was suspended in water.
  • 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 amount of calcium eluted in the aqueous solution of CO 2 is calculated from the measured concentration of calcium in the aqueous solution of CO 2 and the amount of water introduced, divided by the amount of calcium in the steelmaking slag introduced, calcium to the aqueous solution of CO 2 The elution rate of was calculated.
  • Table 2 shows the presence or absence of hydration and the method of hydration when hydration is carried out, the Ca elution method (any of the above Ca elution-1 to Ca elution-4), slag put into the grinding / settling tank or ball mill The amount and the calcium elution rate (Ca elution rate) measured by the above calculation are shown.
  • a grinding area on the bottom side for grinding steelmaking slag, etc. and an elution area on the upper side closer to the liquid surface than the grinding area are provided inside the grinding / settling tank, and the steelmaking slag is ground in the elution area while grinding steelmaking slag.
  • the Ca elution rate was higher than in 7-11 and 14-15.
  • the Ca elution rate was higher as the water / slag ratio corresponding to the amount of water to steelmaking slag was higher.
  • test No. 1 in which the steelmaking slag was subjected to hydration treatment before being brought into contact with the CO 2 aqueous solution. 12 to 13 had a higher Ca elution rate.
  • Example 2 The steelmaking slag shown in Table 1 was crushed so that the diameter was 5 mm or less. Thereafter, the crushed steelmaking slag was heated at 750 ° C. for 40 minutes in the atmosphere. The heated steelmaking slag was further crushed after cooling, and then passed through a sieve with an opening of 106 ⁇ m.
  • a part of the steelmaking slag was magnetically separated by the following method (magnetic separation -1). Thereafter, the steelmaking slag not subjected to the magnetic separation or the steelmaking slag subjected to the magnetic separation was subjected to hydration treatment by the following method (any of hydration treatment-2 to hydration treatment-4). Thereafter, the non-hydrated steelmaking slag and the above-mentioned hydrated steelmaking slag were brought into contact with a CO 2 aqueous solution in the same manner as in Experiment 1 (either Ca elution-1 or Ca elution-3).
  • the steelmaking slag is further crushed using the same grinding / settling tank or ball mill containing the slurry after hydration treatment. Carbon dioxide was introduced into the slurry while equalizing. Then, the elution rate of calcium to the CO 2 aqueous solution was measured.
  • Magnetic selection 0.15 kg of the above steelmaking slag is suspended in 7.5 L of water to form a slurry, which is put into a drum type magnetic separator and charged with a maximum magnetic flux density of 0.03 T on the drum surface and a drum peripheral velocity of 3 m / min. I chose magnetic.
  • the concentration of iron in the steelmaking slag after magnetic separation was measured by chemical analysis, and it was found that 30% by mass of the iron element contained in the first steelmaking slag was removed.
  • the amount of calcium eluted in the aqueous solution of CO 2 is divided by the amount of calcium in the steelmaking slag measured after the magnetic separation to eliminate the influence of the removal of calcium by the magnetic separation to obtain the aqueous solution of CO 2
  • the elution rate of calcium was calculated.
  • Table 3 shows the presence or absence of magnetic separation, the presence or absence of hydration, and the method of hydration when hydration is performed (any of the above hydration treatment-2 to hydration treatment-4), the Ca elution method (the above Ca elution 1 and Ca elution -3), and the calcium elution rate (Ca elution rate) measured by the above calculation are shown.
  • Test was carried out hydration treatment prior to contact with the CO 2 solution No. 21, test No. 22 and the test No. No. 24 had a higher Ca elution rate than the case without hydration treatment (in particular, comparison between Test No. 22 and Test No. 23). Furthermore, tests were conducted magnetic separation prior to contact with the CO 2 solution No. Test No. 22 to No. 22 No. 24 had a higher Ca elution rate than the case where magnetic separation was not performed (in particular, comparison between Test No. 22 and Test No. 21).
  • Example 3 The steelmaking slag shown in Table 1 was crushed so that the diameter was 5 mm or less. Thereafter, the crushed steelmaking slag was heated at 750 ° C. for 40 minutes in the atmosphere. The heated steelmaking slag was further crushed after cooling, and then passed through a sieve with an opening of 106 ⁇ m.
  • a portion of the steelmaking slag was hydrated by the following method (hydration-5). Thereafter, the hydrated steelmaking slag was magnetically selected by the following method (one of magnetic selection-2 to magnetic selection-3). Thereafter, the slurry remaining after magnetic separation was brought into contact with a CO 2 aqueous solution in the same manner as in Experiment 1 (Ca elution-1).
  • Table 4 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 the same as in Experiments 1 and 2.
  • test No. 1 which performed magnetic selection after performing a hydration process. All of 31 to 32 had high Ca elution rates.
  • 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.

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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 carbone. À cet effet, l'invention concerne un procédé d'élution de calcium à partir de scories d'élaboration d'acier. Selon ce procédé, le mélange d'une bouillie contenant des scories d'élaboration d'acier dans une région côté partie supérieure à proximité d'une face liquide de la partie interne d'une cuve d'élution / décantation, est inhibé, et lesdites scories d'élaboration d'acier sont soumises à une décantation, simultanément, les scories d'élaboration d'acier contenues dans ladite bouillie, sont pulvérisées, ou alors la surface desdites scories d'élaboration d'acier est broyée, dans une région côté partie fond de la partie interne de ladite cuve d'élution / décantation. En outre, un dioxyde de carbone est introduit dans ladite bouillie, et lesdites scories d'élaboration d'acier pulvérisées ou broyées, et la solution aqueuse dans laquelle ledit dioxyde de carbone est dissout, sont mises en contact.
PCT/JP2018/041632 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 WO2019107115A1 (fr)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010110088A1 (fr) * 2009-03-25 2010-09-30 国立大学法人東京大学 Procédé de purification de la fluorine
JP2011016710A (ja) * 2009-06-08 2011-01-27 Kobe Steel Ltd 鉄鋼スラグ粉末の炭酸化処理方法およびその装置
JP2011093761A (ja) * 2009-10-30 2011-05-12 Jfe Steel Corp 硫黄・Ｃａ含有スラグの処理方法
JP2011093760A (ja) * 2009-10-30 2011-05-12 Jfe Steel Corp 硫黄含有スラグの処理方法
JP2016179909A (ja) * 2015-03-23 2016-10-13 日新製鋼株式会社 製鋼スラグからカルシウムを含有する固体成分を回収する方法、および回収された固体成分
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 (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010110088A1 (fr) * 2009-03-25 2010-09-30 国立大学法人東京大学 Procédé de purification de la fluorine
JP2011016710A (ja) * 2009-06-08 2011-01-27 Kobe Steel Ltd 鉄鋼スラグ粉末の炭酸化処理方法およびその装置
JP2011093761A (ja) * 2009-10-30 2011-05-12 Jfe Steel Corp 硫黄・Ｃａ含有スラグの処理方法
JP2011093760A (ja) * 2009-10-30 2011-05-12 Jfe Steel Corp 硫黄含有スラグの処理方法
JP2016179909A (ja) * 2015-03-23 2016-10-13 日新製鋼株式会社 製鋼スラグからカルシウムを含有する固体成分を回収する方法、および回収された固体成分
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

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