JP2008261042A - Solidified product of steelmaking dust, and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the solidified matter of steelmaking dust and a method for producing the same, wherein strength required for treatment is obtained without including excessive additives, and heat efficiency of the furnace when recharging to a furnace, is improved, and further cost reduction of a production facility is attained. <P>SOLUTION: The solidified product B of steelmaking dust is obtained by charging dust consisting essentially of iron and the oxide thereof produced in a steelmaking production stage of a melting furnace or the like, to a mold 1, and compacting the dust. As the raw material used for forming the solidified product B of steelmaking dust, powder mixture PO obtained by mixing steelmaking dust with powder consisting of essentially carbon is used. The carbon content in the powder mixture is controlled to ≥20 wt.% and the moisture content is controlled to 14 to 20 wt.%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a steelmaking dust solidified material that recycles, as a steelmaking raw material, a dust mainly composed of iron and its oxide generated in a steel production process by a blast furnace or the like, and a method for producing the same.

  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 dust”) contains iron and iron oxide as main components, 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 by the dust collector, and the reuse efficiency will be extremely low.

For this reason, various methods are tried about reuse of steelmaking dust. For example, Patent Document 1 describes a method of adding a thermoplastic to form steelmaking dust into briquettes that are solidified steelmaking dust, and Patent Document 2 forms grinding sludge and steelmaking dust into briquettes. In order to do this, methods for adding a solidification aid are exemplified. Patent Document 3 proposes a method of forming a briquette using a mixed granulated body granulated with steelmaking dust and carbon as main components.
JP 09-316512 A JP 2002-194449 A JP 2006-225729 A

  The methods of adding the additives of Patent Document 1 and Patent Document 2 are both effective methods for producing a strong briquette. However, since the additive serving as a solidification aid such as plastic is added, the process is There is a drawback that it becomes complicated and expensive. Moreover, since an additive causes an environmental load, it is not preferable. The method using the mixed granulated body of Patent Document 3 is an effective method for obtaining molding strength, but it is desirable to refrain from using a granulator as much as possible from the viewpoint of cost and working environment. Depending on the raw material, granulation may not be easy.

  The object of the present invention is to obtain the strength required for handling without containing extra additives, to improve the thermal efficiency of the furnace when re-inserting into the furnace, and to reduce the cost of manufacturing equipment. It is providing the steel manufacture dust solidified material which can aim at, and its manufacturing method.

  The steelmaking dust solidified product of the present invention is a steelmaking dust solidified product obtained by putting steelmaking dust, which is dust mainly composed of iron and its oxides, produced in a steelmaking process in a blast furnace or the like into a mold and press-molding it. The raw material used for forming the steelmaking dust solidified material is characterized in that a mixed powder obtained by mixing steelmaking dust and a powder mainly composed of carbon is used as a raw material.

  The method for producing a steelmaking dust solidified material according to the present invention comprises solidifying a powder mainly composed of iron and its oxide generated in a steel production process in a blast furnace and the like by placing it in a mold and solidifying it by pressing. In the method for producing a solidified steelmaking dust solidified material, a mixed powder obtained by mixing steelmaking dust and a powder mainly composed of carbon is used as a raw material for the raw material used for forming the steelmaking dust solidified material. It is characterized by.

  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 solidification aid is effective in strengthening the strength of the steelmaking dust solidified product. However, when a solidification aid such as plastic is added, the above-mentioned cost and environmental load causes are considered. It is not preferable. According to this invention, the carbon-based powder added to the mixed powder acts as a substitute for the solidification aid, and increases the strength of the steelmaking dust solidified product, so that there is no occurrence of cracks, dropping, etc. Steel solidified solids having excellent strength against the above can be obtained. In addition, the addition of powder containing carbon as a main component is not harmful as a steelmaking raw material, and is beneficial as follows.

  That is, adding a carbon material such as carbon powder to a steelmaking dust solidified material used for recycling of an electric furnace or the like is effective for improving the thermal efficiency of the electric furnace. This is because the added carbon powder self-combusts while reducing the steelmaking dust and generates heat, so that energy input from the outside can be reduced and the thermal efficiency of the furnace is greatly improved. Therefore, the steelmaking dust solidified material added with carbon powder can be an effective means for recycling steelmaking dust. Since the powder containing carbon as a main component is easily obtained in the steel production process or in the vicinity thereof, like the steelmaking dust, the addition of the powder does not lead to an increase in cost.

In the steelmaking dust solidified material and the method for producing the same according to the present invention, the carbon content of the mixed powder of the steelmaking dust and powder mainly composed of carbon may be 20% by weight or more. More preferably, it is 25% by weight or more. The carbon content mentioned here is the ratio of the powder containing carbon as a main component to the whole raw material.
The powder containing carbon as a main component functions as a solidification aid as described above. When the carbon content in the mixed powder is less than 20% by weight, it is difficult to obtain good molding strength. By making the carbon content 20% by weight or more, a practically sufficient strength of the steelmaking dust solidified product can be obtained. Moreover, the improvement effect of the thermal efficiency of the furnace in the case of recharging to a furnace is acquired. The powder containing carbon as a main component is not limited to pure carbon, and may be graphite, for example.

In the steelmaking dust solidified material and the method for producing the same according to the present invention, the mixed powder may have a moisture content of 14 to 20% by weight. More preferably, it is 15 to 19% by weight.
When the moisture content is less than 14% by weight, a layered crack is generated in a direction perpendicular to the molding pressure direction at the time of demolding after pressure molding, and the strength of the steelmaking dust solidified product becomes weak. On the contrary, if the moisture content exceeds 20% by weight, cracks will not occur, but it is thought that it cannot be sufficiently compressed due to the effect of incompressible water during pressure molding, and the strength of the steelmaking dust solidified material is reduced. To do.

The steelmaking dust solidified product of the present invention is a steelmaking dust solidified product obtained by putting steelmaking dust, which is dust mainly composed of iron and its oxides, produced in a steelmaking process in a blast furnace or the like into a mold and press-molding it. Because the raw material used for forming the steelmaking dust solidified material is a mixed powder that is a mixture of steelmaking dust and carbon-based powder, it does not contain extra additives and is necessary for handling. In addition, it is possible to improve the thermal efficiency of the furnace at the time of recharging the furnace, and to reduce the cost of manufacturing equipment.
The method for producing a steelmaking dust solidified material according to the present invention comprises solidifying a powder mainly composed of iron and its oxide generated in a steel production process in a blast furnace and the like by placing it in a mold and solidifying it by pressing. In the method for producing a solidified steelmaking dust solidified material, a mixed powder obtained by mixing steelmaking dust and a powder mainly composed of carbon is used as a raw material for the raw material used for forming the steelmaking dust solidified material. Therefore, it is possible to produce a steelmaking dust solidified material that does not contain extra additives, can obtain the strength required for handling, and can improve the thermal efficiency of the furnace when re-inserted into the furnace. Cost reduction of equipment can be achieved.

A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a molding apparatus for solidifying steelmaking dust generated in a melting furnace, in which (A) is a cutaway side view thereof and (B) is a plan view thereof. The molding apparatus has a circular index table 2 on which a molding die 1 is formed, and the molding die 1 is provided at four positions on the circumference around the rotation center of the index table 2 at equal intervals. . The inner surface of the mold 1 is a cylindrical surface. A kneader 3 is installed in the vicinity of the index table 2. This kneading machine 3 is charged with steelmaking dust and carbon-based powder (hereinafter referred to as “carbon powder”) from a hopper (not shown), and kneading these steelmaking dust and carbon powder with water. The mixed powder is used as a raw material for the steelmaking dust solidified product B in the mold 1.
The carbon powder is not limited to pure carbon powder, and may be graphite. The mixed powder has a carbon content of 20% by weight or more and a moisture content of 14 to 20% by weight. The carbon content said here is the ratio of the said carbon powder with respect to the whole raw material.
The kneading machine 3 is provided with a feeding screw 4 for feeding the kneaded raw material into the molding die 1 at a raw material feeding portion 21 which is one indexing stop position of the molding die 1 of the index table 2. A comb-shaped material push-in rod 5 that can be moved up and down is disposed above the raw material input portion 21.

  The index table 2 is configured to rotate, for example, in the direction of the white arrow in FIG. The indexing stop positions of the respective molds 1 in the index table 2 are the pre-molding part 22, the main molding part 23, and the demolding discharge part 24 every 90 ° from the raw material input part 21 to the downstream side in the rotation direction. A pre-molded plunger 6 is disposed in the pre-molded portion 22, a main molded plunger 7 is disposed in the main molded portion 23, and a demold discharge rod 8 (see FIG. 2F) is disposed in the demold discharge portion 24. Yes. FIG. 1A shows the state of the molding process in the raw material charging part 21, the pre-molding part 22 and the main molding part 23 in cross section.

  The manufacturing process of the steelmaking dust solidified material by the molding apparatus having this configuration will be described with reference to FIGS. A raw material (mixed powder) P0 obtained by kneading steelmaking dust, carbon powder, and water in a predetermined ratio in the kneading machine 3 is charged into the molding die 1 located in the raw material charging portion 21 by operating the charging screw 4. As shown in FIG. 2A, the raw material P0 put into the mold 1 includes an air reservoir P0a. At this position, the material pushing rod 5 is lowered as shown in FIG. 2 (B) and moved up and down to push the raw material P0 into the mold 1 while collapsing the air pocket P0a. Next, the index table 2 is rotationally indexed, and the molding die 1 filled with the raw material P0 is transferred to the pre-molding unit 22. In the pre-molded portion 22, as shown in FIG. 2C, the raw material P0 is pressurized from above and below by the pre-molded plungers 6 and 6. In FIG. 2D, the pressure applied by the pre-molded plungers 6 and 6 is released, and a pre-molded product P1 is obtained. At the time of this pre-molding and release of pressure, most of the air contained in the raw material P0 is excluded.

The pre-formed product P <b> 1 molded by the pre-molding unit 22 moves to the main molding unit 23 together with the mold 1 by the index of the index table 2. In the main molding portion 23, as shown in FIG. 2 (E), the main molding plungers 7 and 7 are pressurized from above and below to perform the main molding. The main molded product P2 is obtained by releasing the pressure of the main molding plungers 7 and 7. After the pressure is released, the main molded product P2 is transferred to the mold releasing unit 24 together with the molding die 1 by the index of the index table 2. In the mold release unit 24, as shown in FIG. 2 (F), the mold release bar 8 is lowered, the molded product P2 is pushed out from the mold 1 and discharged, and the briquette as shown in FIG. 3 (A). A steelmaking dust solidified product B is obtained.
As for the size of the steelmaking dust solidified product B, for example, the diameter is preferably 30 to 200 mm, and the ratio of height to diameter (height) / (diameter) is preferably 30 to 150%.

  Since the steelmaking dust solidified product B produced in this way is a mixed powder obtained by mixing steelmaking dust and carbon powder as a raw material, it does not contain extra additives and has the necessary strength for handling. And an improvement in the thermal efficiency of the furnace upon recharging into the furnace is obtained. That is, since the carbon powder acts as a substitute for the solidification aid and increases the strength of the steelmaking dust solidified product B, a steelmaking dust solidified product having no cracks and excellent strength against dropping or the like is obtained. Moreover, the addition of carbon powder is not harmful as a steelmaking raw material, and is effective for improving the thermal efficiency of the electric furnace. This is because the added carbon powder self-combusts while reducing the steelmaking dust and generates heat, so that energy input from the outside can be reduced and the thermal efficiency of the furnace is greatly improved. Further, a process such as granulation can be omitted or simplified, and the cost of manufacturing equipment can be reduced. When the next process is sequentially performed while indexing the mold 1 as described above, the productivity is improved as compared with the case where all the processes are performed at one place.

  In addition, when the amount of moisture and the amount of carbon powder are not appropriate, when the removal of bubbles is insufficient, or when the molding speed is not appropriate, a crack c occurs as shown in FIG. It may break easily. However, in this embodiment, since the carbon content of the mixed powder is set to 20% by weight or more and the moisture content is set to 14 to 20% by weight, as will be described later along with the test results, The necessary strength can be obtained.

  In the above embodiment, the example in which the pre-molding and the main molding are performed by pressing with the plungers 6 and 7 from above and below has been shown, but the molding is performed by closing one end side of the mold 1 and pressing only from the other end side. It is also possible to do this. However, since the molding pressure may not be sufficiently transmitted to one end side due to the internal friction of the raw material P0 or the friction on the wall surface of the molding die 1, it is better to pressurize both from the viewpoint of molding strength. Further, the discharge of the steelmaking dust solidified substance B by the demolding discharge rod 8 can be performed upward as well as the downward direction as shown in the figure.

FIG. 4 shows another embodiment of the method for producing a steelmaking dust solidified material of the present invention. Specifically, a modification of the pre-molded portion 22 in the manufacturing process will be shown. In the pre-molded portion 22 of this example, pressure is applied from above and below by the pre-molded plungers 6 and 6 with the porous bodies 6a and 6a made of sintered metal or the like disposed above and below the raw material P0 filled in the mold 1. When the mold 1 and the upper and lower plungers 6 and 6 are directly pressurized, the air escape field is only the gap between the mold 1 and the plungers 6 and 6, and it is difficult for the air to be discharged. , 6a is used to perform pressure forming, and air is exhausted to the outside through the pores of the porous bodies 6a, 6a, so that the removal of air from the raw material P0 is promoted and the formation of cracks is suppressed. Strength is improved.
It should be noted that it is desirable to apply a reverse pressure during non-pressurization to prevent clogging of the porous body 6a. From the viewpoint of clogging, it is difficult to apply the porous body 6a in the main molding portion 23 having a high molding pressure.

  As a method of suppressing cracks due to air contained, in addition to the method of performing the pre-molding by interposing the porous body 6a as described above, the raw material P0 is pressurized a plurality of times when charged into the molding die 1, or It is also effective to vibrate the plunger 6 or the mold 1 during pressurization at the pre-molding portion 22.

  Next, test examples will be described. A forming die and a plunger corresponding to the main forming portion 23 in FIG. 1 were prepared, and the size of the steelmaking dust solidified product was formed at Φ70 × 60 mm, and a solidification experiment was performed. Pure carbon was used for the carbon powder. The drop strength was measured by measuring the number of drops that resulted in cracking by repeatedly dropping the formed steelmaking dust solids up to 20 times from a height of 50 cm on a 3 cm thick mixed powder of steelmaking dust and carbon powder. It is a thing.

  FIG. 5 shows the results of examining the relationship between the ratio of the carbon powder of the forming raw material and the drop strength in the case of pre-molding and twice-molding. Even when it was dropped 20 times and did not break, it was plotted at 20 times. The molding conditions in this case were a molding pressure of pre-molding of 24 MPa, a molding pressure of main molding of 50 MPa, and a molding speed of 30 mm / sec. Since the appropriate amount of water changes depending on the proportion of carbon powder, the amount of water was also adjusted. From FIG. 5, if the carbon powder content is less than 20% by weight, cracks are likely to occur, and in order to obtain good molding strength, the carbon powder content of the molding raw material should be in the range of 25% by weight or more. Was found to be effective.

  FIG. 6 shows the result of examining the relationship between the moisture ratio of the molding raw material and the drop strength in the case of the two-time molding. The molding conditions in this case were steelmaking dust / carbon powder; 70/30% by weight, the molding pressure for pre-molding was 24 MPa, the molding pressure for main molding was 50 MPa, and the molding speed was 30 mm / sec. It can be seen that when the moisture content is lower than 14% by weight, layered cracks are generated in the direction perpendicular to the molding pressure direction during demolding, and the drop strength decreases. On the other hand, when the water content exceeds 20% by weight, no cracks are generated, but it can be seen that the drop strength rapidly decreases. This is considered because it cannot compress fully by the influence of non-compressible water at the time of shaping | molding. As a result, it can be seen that 15 to 19% by weight of the moisture content of the forming raw material is effective.

  5 and 6, the molding is performed twice, and the content ratio of the carbon powder in the forming raw material is 20% by weight or more (preferably 25% by weight or more), and the moisture ratio is 14 to 20% by weight (preferably Is 15 to 19% by weight), as shown in FIG. 3 (A), a steelmaking dust solidified product B without cracks is obtained, and good molding strength can be obtained.

(A) is a fracture | rupture side view which shows an example of the shaping | molding apparatus for manufacturing the steel-making dust solidified material of this invention, (B) is the top view. (A)-(F) is a conceptual diagram which shows the method of manufacturing steel-making dust solidified material with the same shaping | molding apparatus. (A) is a perspective view of the steelmaking dust solidified material obtained by the same method, and (B) is a perspective view of the steelmaking dust solidified material in which cracks are generated. It is a conceptual diagram explaining the shaping | molding process in the pre-molding part in the other shaping | molding apparatus which enforces this invention method. It is a graph which shows the experimental result of the relationship between a carbon ratio and drop strength. It is a graph which shows the experimental result of the relationship between a moisture ratio and drop strength.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Mold 2 ... Index table 3 ... Kneading machine 4 ... Feed screw 5 ... Material pushing rod 6 ... Pre-molding plunger 6a ... Porous body 7 ... Main molding plunger 8 ... Demolding discharge rod 21 ... Raw material feeding part 22 ... Before Molding part 23 ... Main molding part 24 ... Demolding discharge part B ... Steelmaking dust solidified material P0 ... Raw materials (mixed powder)
P0a ... Air reservoir

Claims (6)

Steelmaking dust solidified by pressing steelmaking dust, which is dust mainly composed of iron and its oxides generated in the steel production process by a blast furnace, etc. into a mold,
A steelmaking dust solidified product obtained by using, as a raw material, a mixed powder obtained by mixing steelmaking dust and a powder containing carbon as a main component as a raw material used for forming the steelmaking dust solidified product.   The steelmaking dust solidified product according to claim 1, wherein the mixed powder has a carbon content of 20 wt% or more.   The steelmaking dust solidified product according to claim 1 or 2, wherein the mixed powder has a moisture content of 14 to 20% by weight. A method of producing a solidified steelmaking dust solidified product by putting dust formed mainly of iron and its oxides generated in a steelmaking process in a blast furnace or the like into a mold and pressurizing and solidifying it. In
About the raw material used for shaping | molding of the said steelmaking dust solidified material, the mixed powder which mixed the steelmaking dust and the powder which has carbon as a main component is used as a raw material, The manufacturing method of the steelmaking dust solidified material characterized by the above-mentioned.   The method for producing a solidified steelmaking dust according to claim 4, wherein the mixed powder has a carbon content of 20% by weight or more.   The method for producing a solidified steelmaking dust according to claim 4 or 5, wherein the mixed powder has a moisture content of 14 to 20%.

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