JP2019051472A - Magnetic separation method of steel-making slag, and magnetic separation device of steel-making slag - Google Patents

Abstract

To provide a magnetic separation method of steel-making slag capable of heightening Fe concentration in recovery, in a magnetic separation method for recovering a ferrous compound and metallic iron by magnetic separation from slurry steel-making slag.SOLUTION: A magnetic separation method of steel-making slag includes steps of: bringing slurry containing crushed or pulverized particulate steel-making slag into contact with the surface of a rotary drum having a magnetic field formed on at least a part of the surface; and removing a liquid component contained in the slurry rotated and moved along the surface of the rotary drum, by spraying gas onto the surface of the rotary drum.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a magnetic separation method for steelmaking slag and a magnetic separation device for steelmaking slag.

  Steelmaking slag (converter slag, pretreatment slag, secondary refining slag, electric furnace slag, etc.) generated in the steelmaking process is used for a wide range of applications including cement materials, roadbed materials, civil engineering materials, and fertilizers (non-patented) Reference 1 to Non-Patent Document 3). Moreover, some steelmaking slag which is not used for the said use is disposed by landfill.

  Steelmaking slag includes phosphorus (P), calcium (Ca), iron (Fe), silicon (Si), manganese (Mn), magnesium (Mg), aluminum (Al), titanium (Ti), chromium (Cr), It is known that elements such as sulfur (S) are contained. Among these, the element most frequently contained in the steelmaking slag is Ca used in a large amount in the steelmaking process, and usually contains the next largest amount of Fe. Usually, about 20 mass%-about 50 mass% are Ca and about 1 mass%-about 30 mass% are Fe among the total mass of steelmaking slag.

Fe in the steelmaking slag exists as iron-based oxides, calcium iron aluminum oxide (Ca ₂ (Al _1-X Fe _X ) ₂ O ₅ ), and a small amount of metallic iron. Among these, the iron-based oxide contains Mn or Mg, and contains a small amount of elements such as Ca, Al, Si, P, Ti, Cr, and S. Calcium iron iron aluminum also contains a small amount of elements such as Si, P, Ti, Cr and S. In the present specification, the iron-based oxide includes a compound in which a part of its surface is changed to a hydroxide or the like due to water vapor in the air, and the calcium iron aluminum oxide is water vapor and carbon dioxide in the air. Thus, a compound in which a part of its surface is changed to a hydroxide or a carbonate is also included. In this specification, both iron-based oxides and calcium iron oxides are used as reactants with sulfur oxides (SOx) and nitrogen oxides (NOx), which are part of the surface of the air pollutants. Including these altered compounds.

Most of the iron-based oxides exist as wustite-based oxides (FeO), and also exist as hematite-based oxides (Fe ₂ O ₄ ) and magnetite-based oxides (Fe ₃ O ₄ ).

Among these, the wustite oxide and hematite oxide have a magnetite oxide (Fe ₃ O ₄ ), which is a ferromagnetic material, dispersed therein, so that the steelmaking slag is crushed or pulverized to form particles. Then, it can be separated and recovered from the steelmaking slag by magnetic separation. Note that magnetite-based oxides that are singly or coexist with other iron-based oxides can also be separated and recovered from steelmaking slag by magnetic separation. Furthermore, Patent Documents 1 to 4 describe a method in which a wustite-based oxide is modified into a magnetite-based oxide by oxidation treatment or the like, and more iron-based oxide is separated by magnetic separation.

  Since the calcium iron iron aluminum is magnetized to become a magnetic material, it can be separated and recovered from the steelmaking slag by magnetic separation.

  Iron-based oxides and calcium iron oxides (hereinafter collectively referred to as “iron-based compounds”) have a small phosphorus content of 0.1% by mass or less. If recovered from the slag, it can be used as a raw material for blast furnaces and sintering.

  In the future, due to changes in the social environment, the number of civil works for using steelmaking slag as roadbed materials, civil engineering materials, or cement materials will decrease, and the land where steelmaking slag can be landfilled will decrease. There is also a possibility. Also from this viewpoint, it is expected that the iron-based compound contained in the steelmaking slag is recovered to reduce the volume of the steelmaking slag that is reused or disposed of in landfills.

  Furthermore, Mn, Mg, Ca, and the like contained in the iron-based compound are useful elements in iron making and can be used as materials for iron making. For example, Mn is an element that contributes to improving the strength and stabilizing the strength of the steel material, and Mg is an element that increases the fluidity of slag in the blast furnace. Ca is a main constituent element of slag in blast furnaces and steelmaking, and is an important element for adjusting the basicity and viscosity of slag, but can also be used as a dephosphorizing agent for molten steel.

  Metallic iron is Fe that is engulfed in the slag in the steelmaking process or fine Fe that precipitates during solidification of the steelmaking slag. Large metal iron is separated and recovered by magnetic separation or other methods in a dry process of crushing or pulverizing steelmaking slag in the atmosphere.

  There are many types of magnetic separation methods as described in Non-Patent Document 4 to Non-Patent Document 7. In the case of mass processing industrially, such as magnetic separation for recovering iron-based compounds and metallic iron, a drum-type magnetic separation method using a rotary drum having a magnet fixed therein is often used. In the drum type magnetic separation method, a magnet is fixed in the drum and the outer drum is rotated. The iron-based compound and the metallic iron are captured on the surface of the rotary drum on which a magnetic field is formed by the magnet, and move along the outer periphery of the rotary drum.

  In many cases, slag particles obtained by crushing or pulverizing steelmaking slag are suspended in a liquid such as water to form a slurry, which is flowed to the drum surface and magnetically selected. In the atmosphere, when the particles become small, they aggregate and it becomes difficult to separate the iron compound and others by magnetic separation. However, when slurryed, particles can be dispersed without agglomeration by the liquid, and can be separated by magnetic separation.

  Patent Document 5 describes a method of performing magnetic separation in order to remove iron from rolling oil. In patent document 5, gas is injected to the rolling oil adhering to a drum, and the iron content and rolling oil which were capture | acquired by the drum are isolate | separated.

JP-A-54-88894 JP 54-57529 A JP 52-125493 A JP-A-54-87605 Japanese Patent Laid-Open No. 10-137627

Masao Nakagawa, “Status of Effective Utilization of Steel Slag”, Texts of the 205th and 206th Nishiyama Memorial Technology Lecture, Japan Iron and Steel Institute, June 2011, p. 25-56 “Environmental Materials Steel Slag”, Steel Slag Association, January 2014 Takayuki Nitsuka et al., “Elution behavior of components from steel slag to artificial seawater”, Iron and Steel, Vol. 89, no. 4, January 2014, p. 382-387 Mikio Kobayashi et al., “Powder Purification and Wet Treatment”, Environmental Resource Engineering Society, November 2011, p. 75-84 Tomio Nagashima, “Magnetic Separation”, Journal of Japan Society of Applied Magnetics, Vol. 2, no. 2, 1978, p. 46-53 Tadashi Honma, “Recent Trends of Magnetic Selection Equipment”, Resources and Materials, 1994 Miyagawa Kiyoshi, “Wet drum type magnetic separator as heavy liquid coal preparation equipment”, Journal of the Japan Mining Association, Vol. 94, no. 1088, 1978, p. 697-699

  As described above, since there are many advantages by recovering an iron-based compound from steelmaking slag, there is always a desire to further improve the recovery rate of iron atoms (Fe) by magnetic separation from steelmaking slag. In particular, from the viewpoint of using the recovered Fe as a blast furnace or a raw material for sintering, it is desirable that the Fe concentration in the recovered material is higher.

  In view of the above problems, the present invention provides a magnetic separation method for recovering an iron-based compound and metallic iron from a slurry steelmaking slag by magnetic separation, and a magnetic separation method for steelmaking slag capable of increasing the Fe concentration in the recovered material. It is an object of the present invention to provide a magnetic separator for steelmaking slag that can be used in the method.

  In view of the above object, the present invention includes a step of bringing a slurry containing granular steelmaking slag into contact with the surface of a rotary drum having a magnetic field formed on at least a part of the surface, and the rotation. A step of spraying gas on the surface of the rotary drum to remove the liquid component contained in the slurry that rotates and moves along the surface of the rotary drum, and selecting the steelmaking slag according to the height of magnetization. And a magnetic separation method for steelmaking slag.

  The present invention also provides a rotary drum in which a magnetic field is formed on at least a part of the surface, and a slurry containing steelmaking slag that is disposed in this order in the rotation direction of the rotary drum. A gas is blown onto the surface of the slurry tank and the rotary drum to remove the liquid component contained in the slurry that rotates and moves along the surface of the rotary drum, and the steelmaking slag has a height of magnetization. The present invention relates to a magnetic separator for steelmaking slag having a gas spraying part that sorts according to the above.

  According to the present invention, in a magnetic separation method for recovering an iron-based compound and metallic iron from a slurry steelmaking slag by magnetic separation, the magnetic separation method of the steelmaking slag capable of increasing the Fe concentration in the recovered material, and the method. A magnetic separator for steelmaking slag that can be used is provided.

FIG. 1 is a flowchart of a magnetic separation method for steelmaking slag according to an exemplary embodiment of the present invention. It is a schematic cross section along the rotation direction of a rotary drum which shows a mode that a slurry is magnetically selected using the conventional magnetic separator. FIG. 3A is a schematic cross-sectional view along the direction of rotation of the rotary drum, showing the configuration of the magnetic separator used to magnetically select the slurry in the exemplary embodiment of the present invention. FIG. 3B is a schematic cross-sectional view along the rotational direction of the rotary drum, showing the configuration of another magnetic separator used to magnetically select slurry in an exemplary embodiment of the invention. FIG. 4 is a schematic cross-sectional view along the rotational direction of the rotary drum, showing how the slurry is magnetically selected in the exemplary embodiment of the present invention. FIG. 5A is a schematic cross-sectional view along the direction of rotation of the rotary drum, showing the direction in which gas is blown onto the surface of the rotary drum in an exemplary embodiment of the invention. FIG. 5B is a partial schematic cross-sectional view along the direction of rotation of the rotary drum, showing the angle at which gas is blown onto the surface of the rotary drum in an exemplary embodiment of the invention.

  Hereinafter, the magnetic separation method of the steelmaking slag which concerns on exemplary embodiment of this invention is demonstrated with the magnetic separation apparatus used for the said method.

  FIG. 1 is a flowchart showing a magnetic separation method for steelmaking slag according to the present embodiment.

  The size of the structures such as calcium silicate, free lime and iron-based compounds contained in the steelmaking slag is about 1000 μm or less. Therefore, separation and recovery of components such as iron-based compounds from the steelmaking slag are performed by crushing or pulverizing the steelmaking slag (step S110).

  The type of steelmaking slag is not particularly limited as long as it is slag discharged in the steelmaking process. Examples of steelmaking slag include converter slag, pretreatment slag, secondary refining slag and electric furnace slag.

  Steelmaking slag is crushed or pulverized after being discharged in the steelmaking process to form particulate slag particles. The maximum particle size of the slag particles is preferably about the same as or smaller than the structure of the iron-based compound, and more preferably 1000 μm or less. When the maximum particle size is 1000 μm or less, the iron-based compound can exist as a single particle, and therefore it is easy to selectively select the iron-based compound by magnetic separation. From the same viewpoint, the maximum particle size of the slag particles is preferably 500 μm or less, more preferably 250 μm or less, and further preferably 100 μm or less. The slag particles can be reduced to such an extent that the maximum particle size falls within the above range, for example, by further crushing the crushed slag particles with a pulverizer including a hammer mill, a roller mill and a ball mill.

  The steelmaking slag is preferably heat-treated before magnetic separation. When the steelmaking slag is heat-treated, the magnetization of the iron-based compound increases, and a larger amount of the iron-based compound can be removed by magnetic separation. The heat treatment is preferably performed at 300 ° C. to 1000 ° C. for 0.01 minutes to 180 minutes.

  The steelmaking slag may be an unfiltered residual slag obtained by immersing the steelmaking slag in water, leaching free lime and calcium hydroxide, and leaching Ca on the surface layer of the Ca compound, followed by filtration. . When the filtration residual slag is used, since the slag particles with less Ca are used, it is possible to further increase the Fe concentration in the recovered material, and more separation and recovery of Ca from the slag particles not recovered by magnetic separation. It becomes easy.

  The slag particles thus reduced in particle size have low dispersibility in the air, and are particularly prone to agglomerate due to the magnetic field during magnetic separation, so that more slag particles containing a large amount of iron-based compounds and other compounds are increased. It is difficult to separate the contained slag particles. For this reason, the slag particles are often magnetically selected by being suspended in a liquid and slurryed (step S120). When slag particles are suspended in a liquid, Ca is eluted from free lime and calcium silicate in the slag particles, and the slurry becomes alkaline. Since each slag particle is negatively charged in an alkaline solution, the dispersibility of the slag particle is increased, and the slag particle containing a large amount of iron-based compounds and the slag particle containing a larger amount of other compounds are separated and recovered. Cheap. In addition, even if the said filtration residual slag is suspended in a liquid, the improvement of the dispersibility of slag particle | grains by elution of Ca which remained in slag particle | grains is show | played. As the liquid, cheap water is often used.

  From the viewpoint of improving both the fluidity of the slurry and the recovery efficiency of Fe, the mass ratio of the steelmaking slag and water may be (steelmaking slag / water) = 1/300 or more and 1/2 or less in terms of mass ratio. Preferably, it is 1/200 or more and 1/5 or less, more preferably 1/100 or more and 1/10 or less.

  Such slurries containing slag particles (hereinafter also simply referred to as “slurry”) include slag particles (hereinafter also referred to as “highly magnetized particles”) containing a large amount of iron compounds and large magnetization, free lime and silica. Slag particles containing a large amount of calcium acid or the like but having a small amount of iron-based compound and small magnetization (hereinafter also referred to as “low-magnetization particles”), metallic iron, and liquid components are included.

  The slurry is brought into contact with the surface of the rotary drum having a magnetic field formed on at least a part of the surface (step S130). Thereby, highly magnetized particles and metallic iron are captured on the surface of the rotary drum by the magnetic field, moved in the rotational direction of the rotary drum, and recovered by the recovery unit. On the other hand, the low magnetization particles and the liquid component contained in the slurry are not captured by the surface of the rotary drum, and thus do not move in the rotation direction of the rotary drum and are discharged without being collected by the collection unit. The slurry is preferably brought into contact with an area where a magnetic field is formed on the surface of the rotary drum, but is rotated along the surface of the rotary drum while being brought into contact with an area where no magnetic field is formed. You may move to the area | region where a magnetic field is formed by movement.

  At this time, a part of the low magnetization particles and the liquid component may move along the surface of the rotary drum to the recovery unit and be recovered together with the high magnetization particles. In order to increase the concentration of Fe contained in the recovered material separated and recovered by magnetic separation, the amount of highly magnetized particles and metallic iron separated and recovered is increased while the recovered low magnetized particles and liquid components are It is desirable to select the highly magnetized particles and the low magnetized particles so as to reduce the amount of.

  Therefore, in this embodiment, gas is blown onto the surface of the rotary drum in contact with the slurry, the liquid component moving along the surface of the rotary drum is separated from the highly magnetized particles, and the steelmaking slag is removed. Sorting is performed according to the height of magnetization (step S140).

  The reason why the concentration of Fe in the recovered material is increased will be described below.

  FIG. 2 is a schematic cross-sectional view along the rotation direction of the rotary drum, showing a state in which slurry is magnetically selected using the conventional magnetic separator 100.

  The slurry is supplied from the slurry supply unit 110 to the slurry tank 120 and contacts the surface of the rotary drum 130 in the slurry tank 120. At this time, the highly magnetized particles 180 contained in the slurry are captured on the surface of the rotary drum 130 by the magnetic field formed by the magnet 140 and moved in the rotation direction of the rotary drum 130 (in the direction of arrow X in the figure). Thereafter, the highly magnetized particles adhere to the drum surface due to the adhesive force caused by the wettability of water existing between the highly magnetized particles and the drum surface, and move to the recovery unit 160 along the surface of the rotary drum.

  At this time, a part of the liquid component 190 contained in the slurry is discharged from the slurry discharge unit 150, but another part moves along the surface of the rotary drum 130 together with the highly magnetized particles 180. It is collected in 160.

  This is presumably because the liquid component 190 contains Ca eluted from the slag particles and has high wettability with respect to the surface of the rotary drum 130 and the highly magnetized particles 180. That is, since the liquid component 190 has high wettability with respect to the surface of the rotary drum 130, the liquid component 190 is unlikely to be detached from the surface of the rotary drum 130 and moves along the outer periphery of the rotary drum 130, and a part of the liquid component 190 is recovered. It is thought that it reaches 160. In addition, since the liquid component 190 has high wettability with respect to the highly magnetized particles 180, the liquid component 190 moves along the outer periphery of the rotary drum 130 along with the highly magnetized particles 180 captured on the surface of the rotary drum 130. It is considered that a part of it reaches the collection unit 160.

  When the liquid component 190 reaches the recovery unit 160 in this way, in addition to the high magnetization particles 180 containing a large amount of Fe, low magnetization particles suspended in the liquid component 190 are also recovered by the recovery unit 160. It is difficult to increase the Fe concentration to the desired level. Further, the amount of the liquid component 190 that moves along the surface of the rotary drum 130 per unit area increases approximately in proportion to the 1/2 power of the peripheral speed of the rotary drum 130. However, the amount of highly magnetized particles per unit area captured on the surface of the rotary drum is constant regardless of the peripheral speed of the rotary drum. Therefore, it is considered that as the peripheral speed of the rotary drum 130 increases, the incidental amount of the liquid component 190 increases, and the Fe concentration in the recovered material decreases. The reason why the trapping amount of the highly magnetized particles does not depend on the peripheral speed of the rotary drum is considered to be that the trapping amount of the highly magnetized particles mainly depends on the magnetic flux density on the surface of the rotating drum. That is, when a certain amount or more of highly magnetized particles adhere to the drum surface, the magnetic flux density on the surface becomes small due to the magnetic shielding effect, and any more highly magnetized particles cannot be captured. Therefore, even if the peripheral speed is changed, the trapped amount of highly magnetized particles does not change much.

  FIG. 3A and FIG. 3B are schematic cross-sectional views along the rotation direction of the rotary drum, showing the configuration of the magnetic separator 200 used for magnetically selecting the slurry in this embodiment.

  The magnetic separation device 200 is arranged in this order in the rotating drum 230 in which the magnet 240 is fixed inside, and the rotating direction of the rotating drum 230 (the arrow X direction in the drawing) along the outer periphery of the rotating drum 230. The slurry supply unit 210, the slurry tank 220, the slurry discharge unit 250, and the recovery unit 260 are provided.

  As shown in FIGS. 3A and 3B, the magnetic separation device 200 includes a gas blowing unit 270 disposed between the slurry discharge unit 250 and the recovery unit 260, and the gas blowing unit 270 is provided on the surface of the rotary drum 230. Blow gas from. FIG. 4 is a schematic cross-sectional view along the rotation direction of the rotary drum, showing a state where the slurry is magnetically selected using the magnetic separator 200. In the magnetic separation method of the present embodiment, as shown in FIG. 4, the liquid component 290 that is not captured on the surface of the rotary drum 230 is removed from the surface of the rotary drum 230 by blowing a gas from the gas blowing unit 270. As a result, the highly magnetized particles 280 are separated and collected from the liquid component 290 and the low magnetized particles suspended in the liquid component 290 with higher accuracy. Therefore, the magnetic separation method of the present embodiment using the magnetic separation device 200 can further increase the Fe concentration in the recovered material.

  The slurry supply unit 210 is a flow path for supplying slurry to the slurry tank 220. The slurry supply unit 210 may temporarily store the slurry in the storage unit 215 and adjust the amount of slurry supplied to the slurry tank 220.

  The slurry tank 220 holds the supplied slurry, brings the held slurry into contact with the surface of the rotary drum 230, and the magnetic field formed by the magnet 240 causes the highly magnetized particles in the slurry to reach the surface of the rotary drum 230. It is a tank for capturing. The slurry tank 220 may be a flow path for allowing the slurry supplied from the slurry supply unit 210 to flow to the slurry discharge unit 250 as shown in FIG. 3A, or may be a storage tank that temporarily stores the supplied slurry. There may be.

  The flow rate of the slurry when the slurry is flowing in the slurry tank may be the same as the peripheral speed of the rotating drum, may be faster than the peripheral speed of the rotating drum, or may be slower than the peripheral speed of the rotating drum. From the viewpoint of further improving the removal efficiency of the low magnetized particles, the difference between the flow rate of the slurry and the peripheral speed of the rotating drum is preferably 1 m / min or more.

  The rotary drum 230 is a rotary hollow drum whose surface is configured to be rotatable. In the rotary drum 230, a magnet 240 is fixedly disposed so as not to rotate.

  The surface of the rotary drum 230 may be made of a non-magnetic material such as austenitic phase-stabilized austenitic stainless steel, titanium, plastic and ceramic.

  From the viewpoint of moving the highly magnetized particles captured on the surface to the recovery unit 260, the peripheral speed of the rotary drum 230 during magnetic separation is preferably 0.1 m / min or more and 1000 m / min or less, preferably 1 m / min. It is more preferably 500 m / min or less, and further preferably 5 m / min or more and 300 m / min or less.

  The magnet 240 is fixedly disposed along the inner periphery of the rotary drum 230 at a position at least partially overlapping with the region where the slurry tank 220 is disposed. The magnet 240 forms a magnetic field on the surface of the rotary drum 230 and captures highly magnetized particles contained in the slurry on the surface of the rotary drum 230. The magnet 240 is fixedly arranged, and does not follow the rotation of the surface when the surface of the rotary drum 230 rotates, and the magnet 240 is fixedly arranged inside the surface of the rotary drum 230. A magnetic field is formed in the region.

  The magnet 240 may be a permanent magnet or an electromagnet. Permanent magnets are preferred from the standpoint of reducing costs and making it easier to control the magnetic field distribution.

  Although there is a difference in magnetization between the highly magnetized particles and the low magnetized particles, since both magnetize, it is not possible to sort by simply applying a magnetic force as in normal magnetic separation. The magnet 240 is preferably a magnet that sets the maximum value of the magnetic flux density in the vertical direction on the surface of the rotary drum 230 to 50 G or more from the viewpoint of facilitating the capture of highly magnetized particles on the surface of the rotary drum 230. It is more preferable that the magnet be 100G or more. Further, the magnet 240 makes the maximum value of the magnetic flux density in the vertical direction on the surface of the rotary drum 230 not more than 3000 G from the viewpoint of making it difficult to capture the low-magnetized particles and suppressing the decrease in the Fe concentration in the recovered material. A magnet is preferable, and a magnet having a capacity of 1500 G or less is more preferable.

  The magnet 240 preferably has a plurality of magnets arranged along the inner periphery of the rotary drum 230.

  At this time, it is preferable that the plurality of magnets be arranged such that the maximum absolute value of the magnetic flux density in the region to which the gas is blown is larger than in the other regions. In addition, the area | region where the said gas is sprayed means the area | region located on the extension line | wire of the center of the airflow by gas among the surfaces of the rotary drum 230. FIG.

  Further, at this time, the plurality of magnets are preferably arranged so that magnetic fields having different directions are formed on the surface of the rotary drum 230. Specifically, the plurality of magnets include a magnet disposed with the north pole facing the surface of the rotary drum 230 and a magnet disposed with the south pole facing the surface of the rotary drum 230. Is preferred. The magnet arranged with the north pole facing and the magnet arranged with the south pole facing are preferably arranged alternately in the rotation direction of the rotary drum 230. By adopting such an arrangement, the plurality of magnets rotate in the vicinity of the highly magnetized particles by rotating the highly magnetized particles captured on the surface of the rotary drum 230 while moving due to a change in the direction of the magnetic field. Low magnetized particles can be desorbed, and the concentration of Fe in the recovered material can be further increased.

  Further, at this time, from the viewpoint of suppressing the detachment of the highly magnetized particles due to the gas to be blown, the plurality of magnets has a small area on the surface of the rotary drum 230 where the absolute value of the magnetic flux density in the vertical direction is low. It is preferable that they are arranged as described above. Specifically, in the plurality of magnets, on the surface of the rotary drum 230, an interval between regions where the absolute value of the magnetic flux density in the vertical direction is 50% or more with respect to the maximum value on the surface is 50 mm or less. It is preferable to arrange so that it is 40 mm or less, and it is more preferable to arrange so that it is 30 mm or less. By adopting such an arrangement, even if the highly magnetized particles captured in a certain region are moved by the above-mentioned gas spraying or the like, the highly magnetized particles are easily captured in other regions, and the highly magnetized particles are removed. Separation is suppressed.

  The slurry discharge unit 250 is a flow path for discharging low magnetization particles and liquid components that are not captured on the surface of the rotary drum 230 by a magnetic field to the outside of the magnetic separator 200. The slurry discharge unit 250 may be arranged at the end of the slurry tank 220 as shown in FIG. 3A, or is arranged in the middle of the slurry tank 220 as shown in FIG. 3B, and the flow rate of the slurry is adjusted by the discharge valve 255. May be.

  The recovery unit 260 recovers highly magnetized particles that have been captured by the surface of the rotary drum 230 and moved along the outer periphery of the rotary drum 230.

  The gas spray unit 270 includes a nozzle 275 that ejects gas, and sprays the gas ejected from the nozzle 275 onto the surface of the rotary drum 230. As a result, as shown in FIG. 4, the high magnetization particles 280 and the liquid component 290 are separated, and the low magnetization particles suspended in the liquid component 290 and the liquid component 290 are removed and discharged from the slurry discharge unit 250. .

  The gas blowing unit 270 is located in the middle of the slurry tank 220 and the collecting unit 260 in the rotational direction, that is, between the slurry tank 220 and the collecting unit 260 at a position for blowing the gas onto the surface of the rotary drum 230. It only has to be arranged.

  In addition, since slag particles contain Mn and Mg in addition to Fe, even highly magnetized particles have a smaller magnetization than metal iron and are easily detached from the surface of the rotary drum 230. Therefore, from the viewpoint of suppressing the desorption of highly magnetized particles from the surface of the rotary drum 230 due to the blowing of gas, the gas blowing unit 270 includes the surface of the rotary drum 230 shown in FIGS. 3A, 3B, and 4. As shown in FIG. 2, the magnet 240 is disposed on the inner side, and the magnet 240 is disposed at a position where the gas is blown into a region where a magnetic field is formed by the magnet 240. From the above viewpoint, the gas blowing unit 270 has the gas in a region where the absolute value of the magnetic flux density in the vertical direction is 50% or more with respect to the maximum absolute value of the magnetic flux density in the vertical direction on the surface of the rotary drum 230. It is preferable to be arranged at a position to spray.

  In addition, when almost all of the liquid component is removed from the surface of the rotary drum 230 by gravity or the like during the movement along the surface of the rotary drum 230, the gas blowing unit 270 Is preferably arranged at a position where the gas is blown onto a region existing on the surface of the rotary drum 230. By blowing gas to such a region, the liquid component removal efficiency is further increased. Further, when gas is blown against the liquid component in such a region, the removal efficiency of the low magnetized particles is increased by the fluid drag generated by the flow induced by the gas.

  Further, as shown in FIG. 5A, the gas blowing unit 270 is illustrated as directions (d1 to d3 in FIG. 5A) inclined with respect to the tangent line (broken line L in the drawing) of the rotary drum 230 at the position where the gas is blown. ) Is preferably disposed at the position where the gas is blown (illustrated as gas blowing portions 270a, 270b and 270c in FIG. 5A). In the present specification, the tangent of the rotary drum 230 at the position where the gas is blown means the tangent of the rotary drum 230 at the position where the gas is blown in the cross-sectional view along the rotation direction of the rotary drum. .

  As shown in FIG. 5B, the inclination angle θ is an angle (θ1 or θ2 in FIG. 5B) measured so that the angle with respect to the tangent L of the rotary drum 230 is 90 ° or less. When the angle θ is provided, since the highly magnetized particles are pressed against the surface of the rotary drum 230 by the sprayed gas, the desorption of the highly magnetized particles due to the spraying of the gas, in particular, between the regions where the direction of the magnetic field is reversed. Thus, desorption of highly magnetized particles in a region where the magnetic flux density is partially weakened can be further suppressed. At this time, the low magnetization component that is not captured on the surface of the rotary drum 230 is detached from the surface of the rotary drum 230 together with the liquid component due to the fluid drag and the like.

  The gas blowing unit 270 may be disposed at a position where the gas is blown from the collection unit 260 side with respect to the tangent of the rotary drum 230 (the gas blowing unit 270a in FIG. 5A), and the tangent of the rotary drum 230. The gas may be disposed at a position where the gas is blown vertically (the gas blowing portion 270b in FIG. 5A), or may be disposed at a position where the gas is blown from the slurry tank 220 side (the gas blowing portion in FIG. 5A). 270c).

  When the gas is blown from a direction perpendicular to the tangent to the rotary drum 230 or the tangent to the rotary drum 230 (d1 and d2 in FIG. 5A), when the gas is blown with an angle θ1, The liquid contained in the slurry is less likely to cause desorption of the highly magnetized particles due to the air flow, and a decrease in the recovery efficiency of Fe due to the separated highly magnetized particles mixed with the liquid component and separated together with the liquid component. The surrounding contamination due to the scattering of components is less likely to occur.

  When the gas is blown from the slurry tank 220 side with respect to the tangent to the rotary drum 230 or from the direction perpendicular to the tangent to the rotary drum 230 (d2 and d3 in FIG. 5A), the angle θ2 is provided and the gas , Since the amount of gas in the rotating direction of the rotary drum 230 is not increased more than necessary, desorption of highly magnetized particles due to the air current, and the liquid component and gas that are sprayed with low magnetized particles are brought into the slurry recovery unit 260 side. A decrease in the Fe concentration in the recovered material due to the movement and recovery, and surrounding contamination due to scattering of the liquid component contained in the slurry are less likely to occur.

  From the above viewpoint, the angle θ1 or θ2 is preferably 40 ° or more and 90 ° or less with respect to the tangent, more preferably 55 ° or more and 90 ° or less, and 70 ° or more and 90 ° or less. More preferably it is.

  Further, from the viewpoint of promoting the separation of the highly magnetized particles and the liquid component by the gas blowing and suppressing the desorption of the highly magnetized particles, the gas blowing unit 270 has a flow rate of 10 m / s or more and 330 m / s or less. It is preferable to spray the certain gas, and it is more preferable to spray the gas that is 20 m / s or more and 250 m / s or less.

  Further, from the viewpoint of promoting the separation of the highly magnetized particles and the liquid component by the gas spraying and suppressing the desorption of the highly magnetized particles, the gas spraying unit 270 has a spraying amount of 5 l / s · m or more and 180 l / s. It is preferable to spray the gas that is not more than m, and it is more preferable to spray the gas that is not less than 10 l / s · m and not more than 130 l / s · m.

  The flow velocity and amount of the gas are the flow velocity and amount when sprayed on the surface of the rotary drum, but when the gap between the nozzle that blows the gas and the surface to which the gas is sprayed is sufficiently close (for example, 10 mm When it is below, the flow rate of the gas at the nozzle outlet and the amount of the gas emitted from the nozzle outlet can be roughly regarded as the flow rate and amount of the gas blown to the surface of the rotary drum.

  The gas to be blown is not particularly limited, and air (atmosphere), nitrogen, oxygen, hydrogen, water vapor, chlorofluorocarbon gas, or the like can be used. Of these gases, air (atmosphere) is preferable from the viewpoint of lowering the cost of magnetic separation. In addition, calcium carbonate generated by the reaction between Ca eluted in the slurry and carbon dioxide contained in the gas acts as a binder to aggregate the low magnetization particles with the high magnetization particles, and the aggregated low magnetization particles are recovered. From the viewpoint of suppressing the decrease in Fe concentration in the recovered material, the gas preferably has a carbon dioxide concentration of less than 5% by volume. Further, from the viewpoint of suppressing the reaction of the slurry with nitrogen oxide, sulfur oxide, etc., the gas preferably has a concentration of nitrogen oxide and sulfur oxide of less than 0.1% by volume.

  In addition, even if the surface of the rotary drum is covered with a resin such as water-repellent urethane resin or fluororesin, the liquid component that moves along the outer periphery of the rotary drum along with the highly magnetized particles cannot be removed. Therefore, the Fe concentration in the recovered material cannot be increased as much as in the present embodiment. In addition, when spherical water droplets are formed on the surface of the rotary drum coated with the water-repellent resin and highly magnetized particles are taken into these water droplets, the highly magnetized particles are removed together with the water droplets, and the Fe recovery efficiency May decrease. The reduction in the recovery efficiency of Fe is particularly likely to occur when the magnetic force on the surface of the rotary drum is weak (the magnetic flux density is low).

  Further, even if the roll is pressed against the surface of the rotary drum to squeeze out the liquid component, the liquid component and low-magnetization particles to be removed pass between the surface of the rotary drum and the surface of the roll. Therefore, the Fe concentration in the recovered material cannot be increased as much as in the present embodiment. In particular, since the surface after the highly magnetized particles are usually magnetized is uneven, it is difficult to efficiently remove the liquid components and the low magnetized particles in the recesses. Furthermore, in order to maintain the removal efficiency of the liquid component and the low magnetized particles, maintenance for removing the slag particles adhering to the surface of the roll is necessary, and the work efficiency of magnetic separation is lowered.

  The solid or slurry steelmaking slag after removing the iron-based compound and metallic iron by magnetic separation may be subjected to magnetic separation by the above-described process again in order to recover the iron-based oxide and metallic iron more sufficiently.

  The slurry-like steelmaking slag after magnetic separation can be used for cement materials, roadbed materials, civil engineering materials, fertilizers and the like after collecting Ca and P by a known method as necessary.

  In addition, the recovered material recovered by magnetic separation contains many compounds containing Fe, such as iron-based compounds and metallic iron, and therefore can be reused as a raw material for blast furnaces and sintering.

  Hereinafter, the present invention will be described more specifically with reference to examples. These examples do not limit the scope of the present invention to the specific methods described below.

  Steelmaking slag having the components shown in Table 1 was prepared. In addition, the kind and amount of the component contained in steelmaking slag were measured by the chemical analysis method.

  The steelmaking slag was pulverized after heating in the atmosphere at 750 ° C. for 60 minutes to increase the magnetization. The pulverization was pulverized to 200 μm or less by a dry ball mill and then pulverized to 50 μm or less by a wet ball mill.

  A magnetic separator having the configuration shown in FIG. 4 was used. The outer diameter of the drum was 400 mm. The flow rate of the slurry passing between the drum and the slurry tank was adjusted to 40 m / min. The ratio of steelmaking slag to water in the slurry was a mass ratio of steelmaking slag: water = 1: 50. In the drum, a neodymium-based permanent magnet is arranged so that the N and S magnetic poles change in the circumferential direction of the drum.

[Experiment 1]
A drum type magnetic separator with a maximum magnetic flux density of 300 G in the vertical direction on the surface of the rotary drum was used.

  The magnet was arranged inside the rotary drum from the slurry supply port to the gas spraying part. In addition, the magnets have an interval between regions where the magnitude of the magnetic flux density in the vertical method is 50% or more with respect to the maximum absolute value of the magnetic flux density in the vertical direction formed by each magnet on the drum surface. It arrange | positioned so that it might be set to 10 mm.

  The gas spraying part sprayed air (atmosphere) on the surface of the rotary drum. The nozzle that blows out the air is tilted 20 degrees above the horizontal and blows the air upward, so that the nozzle is blown at 90 ° (perpendicular) to the tangent to the rotary drum at the position where the gas is blown. 10 mm apart from the surface of the rotary drum and the surface of the rotary drum. The flow rate of the blown gas was measured at the nozzle outlet. In addition, the center of the air flow of the gas to be blown is set to be directly above the position where the magnetic flux density in the vertical direction by the magnet arranged inside the blown region becomes the maximum value.

  After the slurry was continuously supplied to the magnetic separator for a predetermined time, the type and amount of components contained in the recovered material were measured by a chemical analysis method, and the amount of Fe in the recovered material was measured.

  Table 2 shows the relationship between the peripheral speed of the drum (the speed of the drum surface), the flow velocity of the air blown, and the Fe concentration of the magnetically collected material.

  When air was not blown onto the rotary drum (flow rate 0 m / s), the Fe concentration in the recovered material decreased as the drum peripheral speed increased. This is because the amount of liquid components and low-magnetization particles that are attached to the drum and rotate and move together with the high-magnetization particles is increased.

  On the other hand, when air was sprayed on the rotary drum, the Fe concentration in the recovered material did not decrease even when the drum peripheral speed increased, and the recovered material having a high Fe concentration was stably obtained.

[Experiment 2]
The maximum value of the vertical magnetic flux density on the surface of the rotary drum in the area where air is blown is 400G, and the maximum value of the vertical magnetic flux density on the surface of the rotary drum in other areas is 300G. A type magnetic separator was used.

  The magnet was arranged inside the rotary drum from the slurry supply port to the gas spraying part. Further, the magnet has a magnetic flux density of 50% or more in the vertical method with respect to the maximum value of the magnetic flux density in the vertical direction formed by each magnet on the drum surface from the slurry supply port to the gas spraying portion. It arrange | positioned so that the space | interval between the area | regions used may be 30 mm.

  The gas spraying part sprayed air (atmosphere) on the surface of the rotary drum. The nozzle that blows air has a 10 mm gap between the nozzle outlet and the surface of the rotary drum at a position where air is blown to a position where the horizontal plane passing through the rotation axis of the rotary drum intersects the surface of the rotary drum. Arranged. The angle of the blown air with respect to the tangent of the rotary drum at the position where the air was blown was changed as shown in Table 3. The flow rate of the blown gas was 55 m / s at the nozzle outlet. In addition, the center of the air flow of the gas to be blown is set to be directly above the position where the magnetic flux density in the vertical direction by the magnet arranged inside the blown region becomes the maximum value.

  The peripheral speed of the rotary drum was 20 m / min.

  During the magnetic separation, the state of the particles (magnetized matter) trapped on the surface of the rotary drum at the position where air was sprayed and the liquid component was visually observed. The results are shown in Table 3.

  In Table 3, when the air blowing angle is a positive value, air is blown from the recovery unit 260 side or the vertical direction of the rotary drum 230 with the angle described with respect to the tangent to the rotary drum 230. When the air blowing angle is a negative value, it indicates that the air is blown from the slurry tank 220 side of the rotary drum 230 with the stated angle with respect to the tangent to the rotary drum 230. .

  When air was blown at an angle of 40 ° or more with respect to the tangent to the rotary drum, there was no movement of the magnetic deposits and no scattering of the slurry. When air is blown from the rotary drum recovery section 260 side at an angle of less than 40 ° with respect to the tangent to the rotary drum, the magnetic deposits move downward (slurry tank 220 side) and turn into a flowing liquid component. It was mixed. Therefore, the amount of collected magnetic deposits has been reduced. At this time, scattering of liquid components also increased. When air is blown from the slurry discharge unit 250 side of the rotary drum at an angle of less than 40 ° with respect to the tangent to the rotary drum, the magnetic deposits move upward (recovery unit 260 side), and one of the liquid components The part also moved upward and moved to the recovery part. At this time, scattering of liquid components also increased.

  However, in any experiment, the Fe concentration in the recovered material was higher than that in the case where air blowing was not performed (No. 6 to No. 9 in Table 2).

[Experiment 3]
A drum-type magnetic separation apparatus was used in which the maximum value of the magnetic flux density in the vertical direction on the surface of the rotary drum in the area where air was blown and other areas was 700G.

  The magnet was arranged inside the rotary drum from the slurry supply port to the gas spraying part. Further, the magnet has a magnetic flux density of 50% or more in the vertical method with respect to the maximum value of the magnetic flux density in the vertical direction formed by each magnet on the drum surface from the slurry supply port to the gas spraying portion. The spacing between the regions was varied as described in Table 4.

  The gas spraying part sprayed air (atmosphere) on the surface of the rotary drum. The nozzle that blows air has a 10 mm gap between the nozzle outlet and the surface of the rotary drum at a position where air is blown to a position where the horizontal plane passing through the rotation axis of the rotary drum intersects the surface of the rotary drum. Arranged. Air was blown perpendicular to the tangent of the rotary drum at the position where the air was blown. The flow rate of the blown gas was 55 m / s at the nozzle outlet. Further, the center of the air stream of the gas to be blown is positioned between the two positions where the magnetic flux density in the vertical direction by the magnet arranged inside the blown region becomes the maximum value.

  The peripheral speed of the rotary drum was 20 m / min.

  During magnetic separation, the state of particles (magnetized material) trapped on the surface of the rotary drum at the position where air was sprayed was visually observed. The results are shown in Table 4.

  When the distance between the regions where the magnitude of the magnetic flux density in the vertical method is 50% or more is 50 mm or less, the movement of the magnetized material due to the blowing of air did not occur. When the distance between the regions where the magnitude of the magnetic flux density in the vertical method is 50% or more exceeds 50 mm, movement of the magnetic deposit was observed. The magnetized material that moved downwards flowed down together with the liquid component, and flowed away without being recovered.

  However, in any experiment, the Fe concentration in the recovered material was higher than that in the case where air blowing was not performed (No. 6 to No. 9 in Table 2).

  Since this invention can collect | recover higher concentration Fe from steelmaking slag by magnetic separation, it is useful as a collection method of Fe resources in iron making.

100, 200 Magnetic separator 110, 210 Slurry supply unit 120, 220 Slurry tank 130, 230 Rotary drum 140, 240 Magnet 150, 250 Slurry discharge unit 160, 260 Recovery unit 180, 280 Highly magnetized particles 190, 290 Liquid component 215 Storage Part 255 discharge valve 270, 270a, 270b, 270c gas blowing part 275 nozzle

Claims (12)

A step of bringing a slurry containing a granular steelmaking slag into contact with the surface of a rotary drum having a magnetic field formed on at least a part of the surface;
A gas is blown onto the surface of the rotary drum to remove the liquid component contained in the slurry that rotates and moves along the surface of the rotary drum, and the steelmaking slag is selected according to the height of magnetization. And a process of
Magnetic selection method for steelmaking slag, including   The magnetic separation method according to claim 1, wherein the gas is blown to a region of the surface of the rotary drum where a magnetic field is formed.   The magnetic separation method according to claim 1 or 2, wherein the gas is blown from an inclined direction with respect to a tangent of the rotary drum including a position where the gas is blown.   The magnetic separation method according to claim 1, wherein the gas is blown from a direction in which an angle of 40 ° or more is provided with respect to a tangent of the rotary drum including a position where the gas is blown. .   5. The magnetic separation method according to claim 1, wherein the rotary drum has magnetic fields of different directions formed on the surface.   The rotary drum is formed so that a magnetic field on the surface is 50 mm or less in an interval between regions where a magnetic flux density in a vertical direction is 50% or more with respect to a maximum value on the surface. 6. The magnetic separation method according to any one of 5 above. A rotating drum in which a magnetic field is formed on at least part of the surface, and
Arranged in this order in the rotational direction of the rotary drum,
A slurry tank for bringing a slurry containing steelmaking slag into contact with the rotary drum, and a liquid component contained in the slurry that rotates and moves along the surface of the rotary drum by blowing gas onto the surface of the rotary drum. A gas spraying part that removes and sorts the steelmaking slag according to the height of magnetization;
Magnetic separator for steelmaking slag having   The said gas spraying part is a magnetic separation apparatus of Claim 7 arrange | positioned in the position which sprays the said gas to the area | region in which the magnetic field is formed among the surfaces of the said rotary drum.   The magnetic separation device according to claim 7 or 8, wherein the gas spraying unit is disposed at a position where the gas spraying part sprays from a direction inclined with respect to a tangent of the rotary drum including a position where the gas is sprayed.   The said gas spraying part is arrange | positioned in the position which sprays the said gas from the direction which provided the angle of 40 degrees or more with respect to the tangent of the said rotary drum containing the position where the said gas is sprayed. The magnetic separator according to any one of the above.   The said rotary drum is a magnetic separation apparatus of any one of Claims 7-10 which has several magnets which form the magnetic field of a different direction on the surface of the said rotary drum.   The rotary drum has a plurality of magnets arranged at positions where the magnetic field on the surface has an interval between regions where the magnetic flux density in the vertical direction is 50% or more of the maximum value on the surface is 50 mm or less. The magnetic separator according to any one of claims 7 to 11.

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