JP5625313B2 - Separation method of steel slag - Google Patents

Description

  The present invention relates to the recycling of slag (iron slag) generated in the iron making process (especially hot metal pretreatment and converter process), and the iron slag is converted into iron and other slag components (non-iron). The present invention relates to a method for separating slag for separation.

  Enormous slag (iron slag) is generated in the iron making process, particularly in the hot metal pretreatment and the converter process. These slags are produced by the reaction and generation of calcium-based additives added to remove impurities and unwanted elements in hot metal and molten steel, and the slag contains a large amount of iron as well as the removed elemental compounds. . Most of the slag forms are massive, and the size of the slag is large and some hundreds of millimeters.

  As described above, since the slag contains a large amount of iron, studies on recycling of the slag have been actively conducted.

  For example, in order to separate and collect iron from slag and mix it with scrap in the converter process to make a cold iron source, first, a large slag lump of several hundred mm is shaped with a sieve (grid type sieve) called grits. Sort out. Next, the small slag block that has passed through the grind-type sieve has an iron block and a non-ferrous block fixed to each other. After promoting the simple separation of iron and non-ferrous component, the magnetic component is separated from iron and non-ferrous component. As the magnetic separator, a hanging type, a drum type, a pulley type, or the like is used.

  In some cases, heating is performed to separate iron, and the subsequent cooling time is controlled for crushing. Depending on the cooling time, it is possible to crush and separate only the non-ferrous lump that is fixed without crushing the iron lump. Or it can be atomized to about several tens of μm.

  Needless to say, if atomization progresses in any of the methods, the separation of iron and non-ferrous metals will progress.

JP 2006-142136 A Japanese Patent Laid-Open No. 10-130041

  In order to improve the separation concentration of iron from steelmaking slag, it is necessary to proceed with the separation of iron and non-ferrous as a single substance. The particle size is reduced by repeating mechanical crushing. Alternatively, the particle size may be reduced by heat treatment.

  On the other hand, in general, when the particle size is reduced in a conventional magnetic separator, as shown in FIG. 4, a embracing phenomenon in which non-ferrous particles (non-magnetic particles) are sandwiched between magnets and iron-containing particles (magnetic particles). In addition, it is difficult to improve the separation concentration due to the aggregation phenomenon caused by dry atomization. Therefore, it is necessary to devise measures such as extremely slowing the supply speed to the magnetic separator and reducing the layer thickness. However, since it is necessary to process several tons to several tens of tons of iron slag per hour, it is not practical to use a magnetic separation device that must extremely slow the supply speed.

  On the other hand, in Patent Document 1, it is also considered to separate the iron and non-ferrous components without crushing the slag lump, but it has a complicated separation flow configuration, which causes an increase in processing costs.

  Moreover, in patent document 2, in order to avoid agglomeration by dry atomization, although a wet process is devised, the waste liquid processing cost becomes enormous.

  The present invention has been made in view of the above circumstances, and in order to recycle iron slag generated in the iron making process (particularly, hot metal preliminary treatment and converter process), the iron slag is made of iron ( It is an object of the present invention to provide a method for separating iron slag that can be efficiently separated into an iron component) and a non-ferrous component (non-ferrous component).

  As described above, in order to improve the separation concentration of iron from steelmaking slag, first, it is necessary to atomize the ironmaking slag and promote the separation of iron and nonferrous as a single substance.

  Next, the iron and non-ferrous components are separated from the atomized iron slag. Since the iron slag is premised on a large amount of processing (several tons to several tens of tons per hour), dry processing is preferable. However, in the case of dry processing, powders of 30 μm or less are generally said to be difficult to separate because they aggregate with each other. In addition, as described above, generally, magnetic force sorting has to be slowed down due to particle embrace phenomenon and particle agglomeration phenomenon, and cannot be applied when large-scale processing is assumed.

  Therefore, as a result of intensive investigations to solve the above problems, the present inventors have carried out air-flow transportation of atomized iron slag, and then the specific gravity difference between iron and non-iron (specific gravity of iron is about 7.6). The specific gravity separation based on the non-ferrous specific gravity was about 2.8). That is, if the atomized iron slag is agitated by air current conveyance to break up the agglomeration, and the specific gravity separation of the atomized iron slag is performed in that state, the separation concentration can be kept good and efficient. In addition, it is possible to separate steel slag.

  Based on the above concept, the present invention has the following features.

  [1] Atomization step for atomizing iron slag, an air current conveyance step for air conveying the atomized iron slag, and a specific gravity separation for separating the iron slag conveyed by air current into iron and non-ferrous components by specific gravity separation A method for separating iron slag, comprising a step.

  [2] The method for separating iron slag according to [1], wherein the airflow conveyance path is bent in the airflow conveyance step.

  [3] The method for separating iron slag according to [1] or [2], wherein a baffle plate is installed in the airflow conveyance path in the airflow conveyance step.

  [4] In any one of the above [1] to [3], in the airflow conveying step, an opening is provided in the middle of the airflow conveying path, and an auxiliary airflow is sent into the airflow conveying path from the opening. Steel slag separation method.

  [5] The method for separating iron slag according to any one of [1] to [4], wherein in the specific gravity separation step, specific gravity separation is performed using an airflow centrifugal separator.

  [6] The method for separating iron slag according to any one of [1] to [4], wherein in the specific gravity separation step, specific gravity separation is performed using a horizontal gravity separation device.

  [7] The method for separating iron slag according to any one of [1] to [4], wherein in the specific gravity separation step, specific gravity separation is performed using an inertial difference separation device.

  In the present invention, when separating iron-making slag into iron and non-iron, the atomized iron-making slag is separated by specific gravity separation after being conveyed by air flow, so that it is separated by magnetic separation as in the past. In comparison, iron slag can be efficiently separated into iron and non-ferrous components. As a result, it is possible to recycle iron slag in large quantities and at high speed.

It is a figure which shows the basic process sequence in embodiment of this invention. It is a figure which shows the process sequence in Embodiment 1 of this invention. It is a figure which shows the process sequence in Embodiment 2 of this invention. It is a figure which shows the problem of a prior art (magnetic force selection).

  An embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a flowchart showing a basic processing procedure in an embodiment of the present invention. As shown in FIG. 1, in one embodiment of the present invention, (S1) atomization step of atomizing iron slag, (S2) air current conveyance (stirring) for conveying and agitating atomized iron slag. And (S3) a specific gravity separation step of separating the iron-made slag, which has been stirred by airflow, into iron (weight side) and non-ferrous content (light side) by specific gravity separation.

  Hereinafter, each step will be described.

(S1) Atomization process In an atomization process, iron-making slag is atomized and iron content is separated into single elements. If the atomization is insufficient, the separation concentration in the subsequent process is not improved. For this reason, it is necessary to atomize to an average particle size of about several tens of μm to several hundreds of μm.

  As the atomization method, the first atomization method is mechanical pulverization. For mechanical pulverization of iron slag, a ball mill, a rod mill, a jet mill, a pin mill, or the like is used for fine pulverization after rough pulverization with a hammer crusher or jaw crusher as a coarse pulverizer. The second atomization method is thermal pulverization (heat treatment pulverization). The iron slag is heated to about 1000 to 1300 ° C. and then slowly cooled.

(S2) Airflow transfer (stirring) step In the airflow transfer (stirring) step, the iron slag (fine particles) atomized in the atomization step is airflow transferred. By this air flow conveyance, the fine particles are dispersed in the air flow, and the aggregation of the fine particles is released. That is, the effect of stirring is obtained. This effect realizes a single separated state.

  At that time, it is sufficient that the airflow has a flow velocity necessary for carrying the fine particles, but it is preferable to generate a turbulent flow in order to improve the stirring effect in the airflow conveyance. For this purpose, a method of bending the airflow conveyance path (using a curved pipe as the airflow conveyance path), a method of installing a baffle plate in the airflow conveyance path, or providing an auxiliary airflow (secondary) in the middle of the airflow conveyance path A simple method such as a method of sending an airflow) into the airflow conveyance path (sucking the auxiliary airflow into the airflow conveyance path from the opening or injecting the auxiliary airflow into the airflow conveyance path from the opening) may be used. Moreover, you may combine those methods suitably.

(S3) Specific gravity separation step In the specific gravity separation step, specific gravity separation is performed on the iron-making slag (fine particles) stirred in the air flow (stirring) step to separate iron on the weight side and non-ferrous on the light side. Separate the minutes.

  At that time, since it is preferable to perform the specific gravity separation while being stirred by the air flow in the air flow conveyance (stirring) step, the specific gravity separation device uses an air flow. Specific gravity separators that use airflow (airflow dry specific gravity separators) include cyclone and other airflow centrifuges, horizontal gravity separators that use gravity, and inertia differences that use the difference in the landing point of powder. Any dry specific gravity separator that uses an air flow as a carrier medium, such as a separator, may be used.

  In the case of an airflow centrifuge, the separation particle size is determined by the flow rate and the diameter of the separation device. Since the diameter of the separation device cannot be easily adjusted, the flow rate is adjusted to achieve separation with an appropriate separation particle size.

  The inertia difference separation apparatus is the same, and an appropriate separation particle size is determined at a rate at which the powder is discharged into the chamber.

  A specific gravity separation method other than the above-described airflow-type dry specific gravity separation method, for example, a wet specific gravity separation method such as jig sorting, can achieve high-precision separation, but is difficult to process in large quantities and at high speed. Moreover, the problem of waste liquid treatment arises.

  Thus, in this embodiment, when separating steelmaking slag into iron and non-iron, after atomized ironmaking slag is conveyed and stirred, it is separated by airflow dry specific gravity separation. Compared with the conventional method of separating by magnetic separation, iron slag can be efficiently separated into iron and non-ferrous components. As a result, it is possible to recycle iron slag in large quantities and at high speed.

  Next, what actualized the basic processing procedure in one embodiment of the present invention as described above is shown in FIGS. 2 and 3 as Embodiment 1 and Embodiment 2, respectively.

[Embodiment 1]
FIG. 2A shows a flowchart showing the processing procedure in the first embodiment, and FIGS. 2B and 2C show schematic diagrams of the processing procedure. Hereinafter, each process of this Embodiment 1 is described.

(S1) Atomization step As shown in FIG. 2A, the iron slag is atomized by heat treatment pulverization. That is, the steelmaking slag is heated to 1200 ° C. and then gradually cooled to be atomized to an average particle size of 30 μm.

(S2) Airflow conveyance (stirring) step As shown in FIG. 2 (a), the iron slag (fine particles) atomized in the atomization step is airflow conveyed and stirred. At that time, as shown in FIG. 2B, the flow path is bent and stirred. Alternatively, as shown in FIG. 2 (c), a baffle plate is installed in the flow path and stirred.

(S3) Specific gravity separation step As shown in FIGS. 2 (a) and 2 (b), the iron-making slag (fine particles) stirred in the airflow conveyance / stirring step is separated by gravity with a cyclone, and the iron content is separated on the weight side. And separate non-ferrous components on the lightweight side.

  And the iron part isolate | separated to the weight side is mixed with a scrap in a converter process, and becomes a cold iron source. On the other hand, the non-ferrous material separated on the lightweight side is captured by a bag filter and used for recycling.

[Embodiment 2]
FIG. 3A shows a flowchart showing the processing procedure in the second embodiment, and FIG. 3B shows a schematic diagram of the processing procedure. Hereinafter, each process of Embodiment 2 will be described.

(S1) Atomization step As shown in FIG. 3A, the iron slag is atomized by mechanical pulverization. That is, iron slag is roughly crushed with a Hanmark lasher, and then finely crushed with a rod mill to be atomized to an average particle size of 30 μm.

(S2) Airflow conveyance (stirring) step As shown in FIG. 3A, the iron slag (fine particles) atomized in the atomization step is airflow conveyed and stirred. At that time, as shown in FIG. 3B, an opening is provided in the middle of the flow path, and the secondary air is sucked into the flow path to enhance the stirring.

(S3) Specific gravity separation step As shown in FIGS. 3 (a) and 3 (b), the steelmaking slag (fine particles) stirred in the air flow conveyance / stirring step is separated by specific gravity using a horizontal gravity separation device, Separate the iron content and non-ferrous content on the lightweight side.

  The iron component separated on the weight side is mixed with scrap in the converter process to produce a cold iron source, while the non-ferrous component separated on the lightweight side is utilized for recycling.

  Based on one embodiment of the present invention, iron slag was separated.

  That is, iron slag with a weight ratio of iron: nonferrous = 30: 70 is atomized to an average particle size of 30 μm, and then iron is separated on the weight side by airflow conveyance / stirring and airflow dry specific gravity separation, and nonferrous on the light side The minutes were separated.

  As a result, the weight ratio of weight side: light weight side = 35: 65 was obtained, and the iron content purity on the weight side was 86%, and the non-ferrous purity on the light side was 92%. Moreover, the processing amount at this time was about 30 tons / hour, and separation at a desired processing speed could be carried out.

Claims (7)

An atomization step for atomizing iron slag, an air current conveyance step for air conveying the atomized iron slag, and a specific gravity separation step for separating the iron slag conveyed by air flow into iron and non-ferrous components by specific gravity separation. A method of separating iron slag, comprising: providing an opening in the middle of the airflow conveyance path and feeding an auxiliary airflow into the airflow conveyance path from the opening in the airflow conveyance step . An atomization step for atomizing iron slag, an air current conveyance step for air conveying the atomized iron slag, and a specific gravity separation step for separating the iron slag conveyed by air flow into iron and non-ferrous components by specific gravity separation. A method for separating steelmaking slag, comprising: separating specific gravity using an airflow centrifugal separator in the specific gravity separation step . An atomization step for atomizing iron slag, an air current conveyance step for air conveying the atomized iron slag, and a specific gravity separation step for separating the iron slag conveyed by air flow into iron and non-ferrous components by specific gravity separation. A method for separating steelmaking slag, characterized in that, in the specific gravity separation step, specific gravity separation is performed using a horizontal gravity separation device . An atomization step for atomizing iron slag, an air current conveyance step for air conveying the atomized iron slag, and a specific gravity separation step for separating the iron slag conveyed by air flow into iron and non-ferrous components by specific gravity separation. A method for separating steelmaking slag, characterized in that, in the specific gravity separation step, specific gravity separation is performed using an inertial difference separation device . In pneumatic conveying step, an opening is provided in the middle of the pneumatic conveying path, a method of separating iron slag according to any one of claims 2 to 4 for the auxiliary air flow through the opening, characterized in that fed into the pneumatic conveying path . The method for separating iron slag according to any one of claims 1 to 5, wherein in the airflow conveying step, the airflow conveying path is bent. The method for separating iron slag according to any one of claims 1 to 6 , wherein a baffle plate is installed in the airflow conveyance path in the airflow conveyance step.

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