JP4641785B2 - Method for producing steelmaking dust solidified material - Google Patents

Description

This invention relates to a method of manufacturing a steel manufacturing dust solidified product reusing dusts produced in the steel production process by melting furnace such as a steelmaking raw material.

  In a steel production process, for example, a melting furnace, fine particulate iron and iron oxide blown up are collected as dust by a dust collector. Since this dust (hereinafter referred to as “steel-making dust”) is mainly composed of iron and iron oxide, it is desirable to reuse it. However, since this steelmaking dust is a fine powder, if it is put into the melting furnace as it is, it will fly up and fly, and most of it will be collected again by the dust collector, and the reuse efficiency will be extremely low. As a result, the amount of steelmaking dust generated in Japan has reached hundreds of thousands of tons per year. However, landfill disposal is not limited to the effective use of resources. It is not preferable from the viewpoint of problems and environmental degradation.

For this reason, various methods are tried about reuse of steelmaking dust. For example, Patent Document 1 exemplifies a method of collecting iron oxide in hot metal by making a dust pellet having a diameter of about 2 to 15 mm and charging it into an electric furnace.
Patent Document 2 discloses a method of adding a thermoplastic to form steelmaking dust into briquettes, and Patent Document 3 discloses a method of adding a solidification aid to form grinding sludge and steelmaking dust into briquettes. Illustrated.
JP-A-11-152511 JP 09-316512 A JP 2002-194449 A

Although the method of making the pellet of patent document 1 is easy to handle, such as the process of charging into the electric furnace from the recovered powder for the amount of pelletization, it is a relatively small beret, so it is charged into the electric furnace. There is a problem with efficiency.
The methods of adding the additives of Patent Document 2 and Patent Document 3 are both effective means for producing a strong briquette, but the process becomes complicated because of the addition of an additive that becomes a plastic or a binder. Has the disadvantage of becoming higher. Moreover, since an additive causes an environmental load, it is not preferable.

An object of the present invention is to provide a raw material to be provided in a steelmaking dust solidified product in which a dust mainly composed of iron and its oxide generated in a steel production process by a melting furnace or the like is placed in a mold and solidified by pressure molding. without adding additives such as a binder to dust is to provide a method of manufacturing a steel manufacturing dust solidified was capable of producing a steel manufacturing dust solidified with practically sufficient strength at a low cost.

The method for producing a solidified product of steelmaking dust according to the present invention is a solidified product obtained by putting a dust mainly composed of iron and its oxide generated in a steel production process into a mold and solidifying it by pressure molding. a method of manufacturing a steel manufacturing dust solidified, the dust, a method of solidifying without adding addition to additives for water, the dust is granulated while adding water, the granules of the state And press molding in the mold.

  In forming a steelmaking dust solidified product, increasing the forming pressure does not necessarily lead to an improvement in strength due to internal friction or the like. The use of a binder is effective in strengthening the strength of the steelmaking dust solidified material, but the addition of a binder such as plastic is not preferable from the above-mentioned cost and environmental load causes. Therefore, the present inventor has conducted various investigations and experimental verifications. As a result, under the same molding conditions, the dust is in a powder state when the dust is granulated in a molding die and pressure-molded. It was found that a higher molding density can be obtained than in the case of putting in a mold and pressurizing. By press molding using the granulated dust, practically sufficient strength of the steelmaking dust solidified product can be obtained without using a reinforcing agent such as a binder.

The method of manufacturing a steel manufacturing dust solidified of the present invention, the water content of the granule and 0.5 to 15%.
When the water content of the granulated body is less than 0.5 wt%, molding is almost impossible, such as cracking in the steelmaking dust solidified product after molding. On the other hand, when the moisture content of the granulated body exceeds 15 wt%, the granulated body softens and becomes mud, and granulation is difficult. Further, it is considered that moisture has an effect of reducing friction between powders and facilitating deformation when the granulated body undergoes plastic deformation behavior in the mold. The effect is manifested when the water content is 0.5 wt%. However, when the water content exceeds 10 wt%, the water itself behaves as a liquid, thus improving the apparent density of the steelmaking dust solidified product. It is counterproductive to this. The range of the water content of the granulated product of the steelmaking dust capable of obtaining the strength of a practical steelmaking dust solidified product is 0.5 to 15 wt%.

Steelmaking method for manufacturing dust solidified of this invention, the dust mainly composed of iron and its oxides occurs at the steel production process, by solidified by molding under pressure was placed in a mold, in that solid product a method of manufacturing a certain steel manufacturing dust solidified, the dust, a method of solidifying without adding addition to additives for water, the dust is granulated while adding water, the granules The water content is 0.5 to 15 wt%, and the dust is put into the mold in the state of a granulated body and subjected to pressure molding, so without adding additives such as a binder to the raw material dust provided, A steelmaking dust solidified material having a practically sufficient strength can be produced.

  An embodiment of the present invention will be described with reference to FIGS. In FIG. 1, the steelmaking dust generated in the melting furnace 1 is introduced into the dust collector 3 from the exhaust duct 2 together with the exhaust gas, and the steelmaking dust 11 in the exhaust gas is collected by the dust collector 3 and discharged as powder. . The steelmaking dust 11 is mainly composed of iron and its oxide. The steelmaking dust 11 discharged from the dust collector 3 is thrown into the first hopper 5A in the steelmaking dust solidified material manufacturing apparatus 4 by a conveying means (not shown).

The steelmaking dust 11 thrown into the hopper 5A is supplied to the granulator 19. The granulator 19 is an apparatus that uses the powdered steelmaking dust 11 as a granulated body 11p. The granulating device 19 is, for example, agglomerated by adding appropriate moisture to the powder in a rotating drum (not shown) to form spherical particles. The granulated body 11p has, for example, a particle size of 5 to 15 mm and a moisture content of 0.5 to 15 wt%. The granulated body 11p of the steelmaking dust 11 granulated by the granulator 19 is put into the second hopper 5B.
Note that the first hopper 5A may be omitted, and the steelmaking dust 11 may be granulated in the transfer process by the transfer means.

The hopper 5B has a distribution supply means (not shown), and the granulated body 11p of the steelmaking dust 11 is distributed and charged to a plurality of juxtaposed solidification mechanisms 6 of the steelmaking dust solidified material manufacturing apparatus 4. Is done. The solidification mechanism unit 6 is a mechanism that solidifies the granulated body 11p of the steelmaking dust 11 into a briquette steelmaking dust solidified product (hereinafter referred to as “briquette”) B, and includes a forming die 7.
The hopper 5 or the solidification mechanism unit 6 is provided with a forced filling mechanism 30 that forcibly fills the mold 7 with the steelmaking dust 11 supplied from the hopper 5.

  As shown in an enlarged view in FIG. 2, the solidification mechanism 6 includes a molding die 7 that press-molds steel-making dust 11 that is input from the hopper 5, and a pressure for press-molding the molding die 7. And a pressurizing control means (not shown) for controlling the pressurizing means 8 so as to be a predetermined pressure.

  The forming die 7 is in the shape of a vertically-oriented cylinder chamber, and has a shape capable of forming the granulated body 11p of the steelmaking dust 11 into a columnar body (that is, a cylindrical body) having a circular cross-sectional shape. Specifically, the molding die 7 includes a cylindrical die 7a and a plunger-like lid body 12A inserted into the lower end opening of the die 7a. The lid body 12A is opened and closed by a lid opening / closing mechanism (not shown) having a drive source. The lid body 12 </ b> A may be sealed at one end without entering the molding die 7.

  The pressurizing means 8 includes a plunger 12 that can be moved up and down to enter the mold 7 from above and pressurize the steel-making dust granulated body 11p in the mold 7 and a pressurizer 13 that drives the plunger 12 up and down. Become. The pressurizing device 13 is composed of, for example, a hydraulic cylinder, and its driving is controlled by a pressurizing device control means (not shown). The pressurizing device control means controls the switching valve 16 of the hydraulic circuit 15 that supplies pressure oil to the pressurizing device 13, the motor 18 of the pump 17, and the like. In addition to the hydraulic cylinder, the pressurizing device 13 may be a motor and a rotation / linear motion conversion mechanism (not shown) such as a ball screw that converts the rotation of the motor into a linear motion.

  A method for producing briquette (steel making dust solidified product) B using the steelmaking dust solidified product producing apparatus 4 (FIG. 1) having this configuration and a method for using the produced briquette B will be described. The steelmaking dust 11 generated in the melting furnace 1 and discharged as powder from the dust collector 3 is put into the first hopper 5A. The powdered steelmaking dust 11 is mainly composed of iron and its oxide. The steelmaking dust 11 thrown into the hopper 5A is made into a granulated body 11p by the granulating device 19, put into the second hopper 5B, and supplied from the hopper 5B into the mold 7 of the solidification mechanism section 6. The

In the solidification mechanism 6, a predetermined amount of the granulated body 11p of the steelmaking dust 11 is introduced from the hopper 5 </ b> B into the mold 7, and then the plunger 12 enters the mold 7 by driving the pressurizing device 13. . In this state, a predetermined pressure is applied to the steelmaking dust 11 in the mold 7. In this case, the molding pressure P (MPa) with respect to the pressurized cross-sectional area (that is, the cross-sectional area of the plunger 12) x (mm ² ) is applied so as to be within the set range.
The briquette B manufactured in this way has a cylindrical shape as shown in FIG. The briquette B preferably has a diameter D of 30 to 100 mm and a ratio of the height H to the diameter D (H / D) of 30 to 150%.

  In FIG. 1, briquette B solidified by the solidification mechanism 6 is collected in a recovery container (not shown) and charged into the melting furnace 1 together with other raw materials when the raw material of the melting furnace 1 is charged. As reused. The raw material charged into the melting furnace 1 is, for example, hot metal obtained from a blast furnace as a main raw material, and iron scrap, quick lime, and the like are also used as auxiliary raw materials.

  According to the manufacturing method of briquette B of this embodiment, the steelmaking dust 11 is made into the granulated body 11p with the granulator 19, and in order to perform pressure molding with the molding die 7 in the state of this granulated body 11p, a binder is added. Thus, a briquette having a practically sufficient strength can be produced. The reason will be explained.

  In the solidification of briquette B, when an additive that improves the strength of the molded body such as a binder is not used, the solidification action of briquette B is caused by the rearrangement of powder particles caused by pressure molding and the adhesive force due to contact. To express. Basically, the adhesion force of the powder increases as the contact area between the powders increases, so if the contact area between the powders is increased by increasing the molding pressure, the briquette strength is improved.

  However, the position of the powder particles cannot be freely changed like a liquid, and a frictional force is generated between the powders or between the powder and the mold surface. The molding pressure does not necessarily lead to an increase in strength because the dense filling effect is insufficient and a large void volume is included, or the molding pressure becomes non-uniform due to friction loss and a large density difference occurs inside the molded body. Furthermore, the residual air and the density difference in the voids inside the molded body are large because so-called lamination in which a layered crack occurs in the direction perpendicular to the molding pressure direction at the time of demolding when the molding pressure is released occurs in a lower molding pressure region. It can also be a cause.

  It is effective to improve the fluidity of the powder particles and the mold filling property by adding a binder to reduce the voids inside the molded body and the molding density difference by the molding pressure. In addition, an inexpensive method is pursued, and it is difficult to improve the characteristics of the raw material powder provided.

  For the above reasons, there is a limit to improving the strength of briquette B by increasing the contact area between the powders at the molding pressure (improving the molding density). Therefore, as a result of exploring other methods to improve the forming density and proceeding with various investigations and experimental verifications, using the granulated steelmaking dust as the raw material under the same forming conditions, It has been found that a higher molding density can be obtained than when the raw material is used.

  In a steel production process, for example, in a melting furnace, after the fine particulate iron and iron oxide that have been blown up are collected as dust by a dust collector, the steelmaking dust is made into a dust pellet as shown in Patent Document 1, for example, and granulated. Granulation by a machine is generally performed. The present invention clarifies that a briquette strength practically sufficient can be obtained without using a reinforcing agent such as a binder by molding a briquette using the granulated raw material. .

  In order to investigate the moldability of steelmaking dust, the inventor uses a molding die 21 that is a mold including a cylindrical die 21A and a lower plunger 21C that serves as a lid, and a pressurizing plunger 21B shown in FIG. Then, solidification experiment of the following steelmaking dust was conducted. Note that the die 21A, the lower plunger 21C, and the pressurizing plunger 21B in FIG. 4 are members equivalent to the die 7a, the lid 12A, and the plunger 12 in the solidification mechanism 6 (FIG. 2).

The steelmaking dust used is discharged from the electric furnace and granulated, and has a particle size of 5 to 15 mm. As a comparison object, steelmaking dust powder discharged from the same electric furnace was used.
Table 1 shows the production of a cylindrical briquette B with a diameter of φ70 and a ratio of height to diameter of 80% by changing the molding pressure. The apparent density of the briquette B made into the dry state and the result of the drop strength test of the briquette B are shown.
Table 2 shows the result of comparing the apparent density of the granulated product with the bulk density of the powder.

  In any forming pressure, compared to the powder raw material, the briquette B made from the granulated material has a higher apparent density and drop strength, and the characteristics of the briquette B made from the granulated material are superior. If the comparison is made with the same strength, it indicates that the briquette B made from the granulated material can be solidified at a lower molding pressure. Further, the molding pressure at which lamination occurs is higher when a granulated material is used as a raw material.

  Granulation is performed by agglomerating powder in a rotating drum while adding appropriate moisture to form spherical particles. The apparent density of the granules produced by this method is Since the molding density is higher than the molding density obtained by pressure molding, and the shape retention is made only by cohesion rather than external forcing, the granulation has almost no internal stress such as density difference. Conceivable. When pressure molding is performed using such raw materials, the briquette is deformed into a predetermined shape by the molding die without greatly impairing its apparent density due to the plastic deformation behavior of the granule inside the molding die. By forming the shape of B, it is considered that the apparent density is higher than that of a molded body obtained by pressure molding a powder raw material under the same molding conditions. In addition, regarding the lamination, unless the molding pressure exceeds the apparent density of the granulated body, the increase in the amount of springback due to residual air in the voids and the difference in molding density is not so great. As a result, it is considered that the molding pressure at which lamination occurs is higher than that when the powder raw material is pressed.

  FIG. 5 shows the appearance of a completely dry briquette when a cylindrical briquette having a diameter size of φ70 and a ratio of the height to the diameter of 80% is produced at a molding pressure of 50 MPa using a granulated body with controlled moisture content. The density is shown. When the water content was less than 0.5 wt%, the briquette B after molding had cracks, and the apparent density could not be measured. Although the briquette B can be formed when the water content is 0.5 wt% or more, the apparent density becomes substantially constant when the water content is 1.5 to 10 wt%. When the water content exceeds 10 wt%, the apparent density of briquette B is slightly lowered. When the moisture content of the granulated body exceeded 15 wt%, the granulated body softened and became mud, and the test was impossible.

  From the results of the above examples, it is considered that moisture has the effect of reducing friction between powders and facilitating deformation when the granulated body undergoes plastic deformation behavior in the mold. The effect is manifested when the water content is 0.5 wt% or more, but when the water content exceeds 10 wt%, the water itself behaves as a liquid. Counterproductive. The range of the water content of the granulated product of steelmaking dust that can obtain a practical briquette B strength is 0.5 to 15 wt%. Desirably, it is the range of 1.5-10 wt%.

In the test, briquette production was performed using steelmaking dust discharged from the electric furnace, but the dust used in the present invention may be dust mainly composed of iron and its oxide generated in the steel production process. blast furnace, those that occur in other steel making process you can use.

In the steelmaking dust solidified product manufacturing apparatus of FIG. 1, there is a problem in the filling property (pouring characteristics into the mold 7) of the steelmaking dust granulated body 11p depending on the water content in the powdered portion of the solidifying mechanism unit 6. It is desirable to provide the forcible filling device 30 having a certain level of forcing force.
In particular, there is no restriction on the direction of the mold, and as the compulsory filling device 30, when the direction of the mold 7 is in the vertical direction, a mechanism such as a pusher by a powder feeder or a screw can be used, and the direction of the mold is in the horizontal direction. A mechanism such as pushing with a screw can be used.

It is process explanatory drawing of the steel-making dust solidified material manufacturing method concerning one Embodiment of this invention. It is the schematic of the steel manufacture dust solidified material manufacturing apparatus used for the manufacturing method. It is a perspective view which shows the example of the steelmaking dust solidified material manufactured with the manufacturing method. It is sectional drawing of the shaping | molding die used for the solidification test used as the foundation for obtaining the manufacturing method. It is a graph which shows the relationship between the moisture content of a granulated body, and an apparent density.

Explanation of symbols

4 ... Steelmaking dust solidified product manufacturing apparatus 5A, 5B ... Hopper 6 ... Solidification mechanism 7 ... Mold 8 ... Pressure means 10 ... Pressure control means 11 ... Steelmaking dust 11p ... Granule 12 ... Plunger 19 ... Granulation Apparatus 30 ... Forced filling mechanism B ... Briquette (Steelmaking dust solidified material)

Claims (1)

It is a method for producing a steelmaking dust solidified product, which is a solidified product, by putting the dust mainly composed of iron and its oxide generated in the steel production process into a mold and solidifying by pressure molding ,
The dust, a method of solidifying without adding addition to additives for water, the dust is granulated while adding water, the water content of the granule is 0.5 to 15%, A method for producing a solidified steelmaking dust, wherein the dust is put into the mold in the state of a granulated body and press-molded.

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