JPH0244885B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a metallurgical recarburizer to be added to a metallurgical furnace, such as an electric furnace for steelmaking. [Prior art] Generally, a metallurgical furnace, such as an electric furnace for steelmaking, is used to
When refining high carbon steel, a recarburizer is used to adjust the carbon content during steelmaking. In this case, pig iron, lump coke, powdered coke, etc. are used as recarburizers, but although pig iron is a material with a high carbon yield as a recarburizer, its carbon content is low at about 4%, so the amount of addition is There is a disadvantage that the number of particles increases, and that they are bulky and large, resulting in a long dissolution reaction time and high cost. Furthermore, both lump coke and powder coke have low specific gravity, so they float to the surface of molten steel during steelmaking, resulting in a low carbon yield of 30 to 40%. Furthermore, when coke is used as a recarburizer,
Since it has no magnetism, it cannot be handled by the lifting magnet used for charging the main raw material, so it has drawbacks such as the need to attach a special charging device. It is also possible to use coke powder by blowing it into the injection pipe, but in addition to the drawbacks mentioned above, coke powder only reaches shallow parts of the molten steel, which worsens the environment and still has a low carbon yield. . The present inventors filed an application in Japanese Patent Application No. 59-22939 for a metallurgical recarburizer that improves the drawbacks of these conventional recarburizers. The above invention is based on the use of ultrafine coke powder generated in steel works, etc., which has been limited in its use due to its fine particle size. This is a metallurgical recarburizer made by blending fine coke with a grain size of 1 mm or less and fine iron powder, adding a binder, and molding the mixture. be. This metallurgical carburizer is a metallurgical carburizer that can be used in metallurgical furnaces such as electric furnaces for steelmaking, has a high carbon yield, and can be handled with a lifting magnet or the like. Generally, when converting these metallurgical carburized materials into briquettes or pellets, the steps are: drying of the raw materials, pulverization, mixing, addition of a binder, heating dehydration, compression molding, etc.
A series of moisture adjustment steps are required, and equipment for each step must be installed separately, resulting in relatively high equipment costs. Furthermore, since the metallurgical carburizer is made of fine coke with a particle size of 1 mm or less and fine iron powder containing metallic Fe, such as collected fine iron particles such as converter OG dust, the raw material Fine coke and fine iron powder absorb a large amount of water during accumulation, and the moisture content fluctuates widely.Furthermore, fine iron powder contains metallic Fe and is easily oxidized. According to the method, the crushing strength after molding is low because it is difficult to maintain uniform moisture, and furthermore, the metallic Fe of fine grained iron powder cannot be effectively used as an iron source. development was requested. [Problems to be Solved by the Invention] The present invention involves blending fine coke and fine iron powder with a particle size of 1 mm or less and a large moisture content fluctuation, adding a binder to the mixture, and using the mixture in a metallurgical furnace such as an electric furnace for steelmaking to produce carbon. The object of the present invention is to provide a method for efficiently producing a metallurgical recarburizer that has a high yield and can be handled using a lifting magnet or the like. [Means for Solving the Problems] The present inventors have developed a patent for producing a metallurgical recarburizer consisting of fine coke and fine iron powder.
980334 (Special Publication No. 54-13441), the conventional recarburizer is manufactured by using the "Production method of strong coke briquette coal and equipment used therein" (hereinafter referred to as K and B mixers). By simplifying the steps in the method as much as possible, drying, grinding, and mixing the raw materials.
The five steps of adding a binder and heating and dehydrating are processed in one step, followed by compression molding and moisture adjustment to produce a recarburized material for metallurgy. That is, the gist of the present invention is to use a mixture of fine coke with a particle size of 1 mm or less and fine iron powder as a raw material, and to add a binder to the raw material to produce a recarburized material. The present invention is a method for producing a recarburized material for metallurgy, in which a series of steps of pulverization, addition of a binder, mixing, and heating and dehydration are performed in one step, followed by compression molding and moisture adjustment. Furthermore, the blending ratio of raw material fine coke and fine iron powder is within the range of 10 to 60:90 to 40, the fine iron powder contains metallic Fe in an amount of 50% by weight or more, is converter OG dust, and is fine powder. Coke is preferably coke-quenching equipment (CDQ) dust. The binder added when mixing these raw materials is carboxy methylcellulose (CMC),
Selected from polyvinyl alcohol (poval), propane dei asphalt (PDA) thermoplastic acrylic resin, thermosetting synthetic resin, starch, lignin, inorganic bentonite, cement, water glass, pitch, tar, and wood tar. Type 1 or type 2, of which 1-10% is PDA
Or, polyvinyl alcohol is added and mixed in an amount of 20% or less. When mixing these raw materials, one selected from polyphosphoric acid, tannic acid, boric acid, etc. is used as a rust preventive material.
By adding seeds, oxidation of fine iron particles can be prevented, and iron can be used effectively. In addition, a mixer with high-speed stirring blades that mixes fine coke and fine iron powder supplies heat through a heat supply device and releases raw material moisture outside the mixer by indirect heating. When grinding in the machine, add water to adjust the moisture content. In the process of adding a binder to these raw materials and molding the resulting mixture, it is recommended to use a roll-type molding machine with drainage grooves or a desk-type molding machine with dehydration grooves around the mold circumference for good metallurgical processing. Carbonaceous material is obtained. [Operation] Next, the method of the present invention will be explained based on the process diagram of the present invention shown in FIG. In the coke manufacturing process of steelworks, which normally contains 5 to 10% moisture, for example, coke extinguishing equipment (CDQ)
Fine coke 1 and fine iron powder 1' having a particle size of -1 mm, such as OG dust from a converter, which are collected by the hoppers 3 and 3', are sent to the respective hoppers 3 and 3'. These - 1 mm particle size fine coke 1 and fine iron powder 1'
The raw material is intermittently automatically fed into a high-speed rotating mixer (KB mixer) 5 through a pneumatic pipe 4 according to the required amount of carburization, crushing strength after molding, and molding specific gravity.
In this case, the tip of the pneumatic tube is sealed when the raw material is introduced. A temperature meter 6 measures the internal temperature of the KB mixer 5, and rotating blades 8 and 22 coaxially mounted are rotated at high speed by power 16 through an accelerator/deceleration gear 17. The raw materials inside the KB mixer are pulverized by blades that rotate at high speed, and their temperature rises due to frictional heat. When the thermometer 6 does not reach the preset temperature, the raw material is heated via the steam pipe 15 by a heating source such as electric heat or superheated steam installed in the external heating chamber 9 of the mixer. At this time, the pressure increases.
Alternatively, if the temperature and moisture are insufficient to the predetermined values, water is supplied by pressure from the water supply pipe, and when the predetermined temperature is reached, the accelerator/deceleration is decelerated by the signal, and at the same time water is supplied under pressure from the binder tank 12. A binder is ejected into the mixer 5 through a pump 11 and a pipe 10, and the raw materials (fine coke 1 and fine iron powder 1') are stirred and mixed, and are melted and spread at a high temperature. During this time, the moisture in the raw material turns into steam, and since the mixer is sealed, the internal pressure increases. The pressure is measured by the pressure gauge 7, and if the pressure exceeds a predetermined value, it is discharged to the outside through the exhaust pipe 13 and the pressure regulating valve 14. After the mixing process using the designated KB mixer is completed,
The discharge port 18 is opened, and the product is temporarily stored in a hopper 19 on the molding machine, and then charged into a roll-type molding machine 20 or a desk-type molding machine 21 as a molding machine. As shown in FIG. 2, this roll-type molding machine 20 has a drainage groove 26 that facilitates removal of excess moisture released during compression.
As shown in FIG. 3, the desk-type molding machine 21 is provided with a dewatering groove 27 around the mold circumference. Both have good compression effects. The compression-molded briquettes are passed through a hot air drying oven 23 to adjust the moisture and hardness of the finished product, depending on the properties of the binder used at that time. After passing through the hot air drying oven 23, the product is temporarily stored in a product hopper 24 or sent directly to a steelmaking converter or electric furnace as a recarburizing material for steelmaking. According to this manufacturing method, the molding conditions can be adjusted in the same device in an extremely short time (4 to 6 minutes), and the recarburizer consisting of fine coke and fine iron powder is pulverized in the mixer 5. A series of steps of adding and mixing binder and heating and dehydrating are processed in one step, and then molded in a compression molding machine 20, and if necessary, heated in a hot air drying oven 2.
It is produced by adjusting the moisture content in step 3. In Fig. 1, the operation inside the KB mixer is a batch type operation, but the roll type molding machine 20
Or depending on the molding capacity of the desk type molding machine 21
Two or three KB mixers 5 are installed in parallel, and the mixed raw materials are alternately discharged from the mixer to the hopper 1.
It is also possible to store it in 9 and mold it continuously. In addition, this KB mixer 5 is equipped with an external heating chamber 9, so it can handle moist raw materials with a moisture content of 10 to 15%.
Using saturated steam of 10Kg/cm ² (saturation temperature 170℃),
By indirect heating, it is possible to maintain an appropriate amount of moisture during mixing and stirring. As raw materials for the metallurgical recarburizer according to the method of the present invention, fine coke with a grain size of -1 mm and fine iron powder are used. The method of the present invention is effective when using various types of fine coke, such as dust from CDQ equipment, and in particular when using coke powder collected by wet dust collection equipment such as wet scrubbers, ventilate scrubbers, etc. Next, as the fine iron powder, it is preferable to use one containing metallic Fe, such as converter OG dust, in order to effectively use it as an iron source.
A mixture of seeds is also acceptable. Containing metallic iron in fine iron powder is preferable from the point of view of effective utilization of the iron source, but if there is too much oxygen in fine iron powder, it will cause bumping phenomenon in electric furnaces for steelmaking, so adding iron oxide will be extremely difficult. Since only a small amount can be added, the metallic Fe content is preferably 50% by weight or more.
The content is preferably 60 to 70% by weight. The blending ratio of these fine coke and fine iron powder is
In order to use metallic Fe as an iron source and to ensure the carbon content and specific gravity as a carburizer, a minimum of 10% of fine coke is required, and if the blending ratio of fine iron powder is lowered, the specific gravity of the molded carburizer will decrease. When a carburized material is used, a minimum of 40% is required to float on the steel bath, so the blending ratio is 10-60:90-40, preferably 20-30:80-70. Binders for molding these raw materials include carboxy methylcellulose (CMC), polyvinyl alcohol-poval),
Propane de asphalt (PDA), thermoplastic resin, thermosetting synthetic resin, starch, lignin,
Inorganic bentonite, cement, water glass, pitch, tar, wood tar, etc. are used, and the use of one or two selected from these is effective in ensuring the crushing strength of the recarburizer. Among these binders, poval is preferred from the viewpoint of viscosity, but since it is an aqueous solution,
It is advantageous to use a mixer, such as a KB mixer, which has high-speed stirring blades and is equipped with an indirect heating device in the method of the invention, making it possible to release excess moisture from the mixer exhaust pipe 13 and dehydrate it. Furthermore, as for the amount of binder added, as mentioned above, various binders such as inorganic acphalt-based, pitch-based, cornstarch, etc. can be used, but asphalt-based or pitch-based binders are used in an amount of 1 to 10%, preferably 5 to 10%.
It is preferable to add 8% or more of an organic type such as poval, which is used as an aqueous solution, in an amount of 20% or more in terms of crushing strength and carbon adjustment as a recarburizing material. The crushing strength is usually 80 to 90 when used for electric furnaces.
The metallurgical recarburizer according to the present invention has a sufficient strength of 100 Kg/piece or more according to the method of the present invention. Also, the softening point of coal tar separates at room temperature.
Inside the KB mixer 5, the binder effect is high due to heating and frictional heat. Moreover, the molded shape can be manufactured into any shape such as briquettes or pellets using a roll type molding machine 20 or a desk type molding machine 21. Next, the present invention will be explained based on embodiment examples. [Example] Steel factory converter OG dust (particle size is 1 mm or less)
0.05-0.3 mm, 70-80% M-Fe70%) and coke fire extinguishing equipment (CDQ) collected dust (VM: 0.5%, particle size 0.01-0.2 mm, 70-80%) are mixed in a KB mixer. A specific amount of the binder shown in Table 1 was added to this and mixed, and a double roll molding machine (mold: 53 mm x 53 mm x 14 mm ~ 47 c.c.
R15), and the physical properties of the obtained recarburized material were measured. The above blending conditions and physical properties are shown in Table 1 below. The obtained recarburized material for metallurgy has high crushing strength and apparent specific gravity, high M-Fe in the product, and low moisture content even when an aqueous binder is used, so it can be used as a recarburized material in electric furnaces, etc. We were satisfied with its use.

〔Effect of the invention〕

The formed recarburizer for metallurgy according to the method of the present invention has the following advantages: (1) The density of the formed recarburizer can be controlled to 1 to 6 by controlling the addition of fine iron powder to coke powder at an arbitrary ratio, and it can be used in a steelmaking bath. Carbon can be efficiently added inside. (2) Since the carbon material is originally fine coke powder and has a large surface area, it has high carburization reactivity in a steel bath. (3) Since the size and shape of the molded solid can be controlled arbitrarily, the optimal size and shape can be obtained depending on the depth and width conditions of the steel bath. (4) Since the fine carbon material and fine iron powder are closely and uniformly distributed, some of the iron oxide is reduced and becomes an effective iron source. (5) Compared to using commercial scrap as an iron source, it is a high-quality iron source without impurities such as Cu, Sn, Cr, and Zn (tramp elements). (6) When applied to metallurgical furnaces such as electric furnaces, sufficient strength of the charge can be obtained. It has great effects as a recarburizing material in metallurgical furnaces.

[Brief explanation of the drawing]

FIG. 1 is a process diagram of the method of the present invention, FIG. 2 is a schematic diagram showing a dewatering groove of a roll-type molding machine, and FIG. 3 is a schematic diagram of a mold showing a dehydrating groove of a desk-type molding machine. In the figure, 1: fine coke, 1': fine iron powder, 5: high-speed rotation mixer, 7: pressure gauge, 8,2
2: Rotating blade, 9: External heating chamber, 12: Binder tank, 13: Exhaust pipe, 14: Pressure regulating valve, 18:
Discharge port, 20: Roll type molding machine, 21: Desk type molding machine, 23: Hot air drying oven.

Claims (1)

[Scope of Claims] 1. In the process of producing a recarburized material by adding a binder to the raw material using a mixture of fine coke and fine iron powder, a mixer with high-speed stirring blades is used to crush the raw material and bind the binder. A method for producing a recarburized material for metallurgy, characterized in that a series of steps of addition, mixing, and heating and dehydration are performed in one step, followed by compression molding and moisture adjustment. 2. The method for producing a metallurgical recarburizer according to claim 1, wherein the particle size of the raw material is 1 mm or less. 3. The method for producing a metallurgical recarburizer according to claim 1, characterized in that the blending ratio of the raw materials, fine coke and fine iron powder, is in the range of 10 to 60:90 to 40. 4 The fine iron powder contains 50% by weight of metallic Fe.
The method for producing a recarburized material for metallurgy according to claim 1, characterized in that the above-mentioned content is contained. 5. The method for producing a recarburizer for metallurgy according to claim 1, wherein the fine iron powder is converter OG dust. 6. The method for producing a metallurgical recarburizer according to claim 1, wherein the fine coke is coke quenching equipment (CDQ) dust. 7 The binder is carboxy methylcellulose (CMC), polyvinyl alcohol, propane deasphalt (PDA) thermoplastic acrylic resin, thermosetting synthetic resin, starch, lignin, inorganic bentonite, cement, water glass, pitcher 2. The method for producing a metallurgical recarburizer according to claim 1, wherein one or two selected from the group consisting of , tar, and wood tar are used. 8. The method for producing a recarburizer for metallurgy according to claim 1, characterized in that 1 to 10% of the PDA is added and mixed. 9. The method for producing a metallurgical recarburizer according to claim 1, characterized in that 20% or less of the polyvinyl alcohol is added and mixed. 10. The method for producing a metallurgical recarburizer according to claim 1, characterized in that a rust preventive material is added during the mixing. 11. The method for producing a carburizer for metallurgy according to claim 10, wherein the rust preventive material is one selected from polyphosphoric acid, tannic acid, and boric acid. 12. Claim 1, characterized in that, in the mixer having the high-speed stirring blades, heat is supplied through a heat supply device and moisture of the raw material is discharged to the outside of the mixer through indirect heating. A method for producing a recarburized material for metallurgy. 13. The method for producing a metallurgical recarburizer according to claim 1, wherein in the pulverizing step, water is added to the mixer to adjust the moisture content. 14. Metallurgical carburization according to claim 1, characterized in that, in the compression molding step, a roll type molding machine provided with a drainage groove or a desk type molding machine provided with a dehydration groove on the circumference of the mold is used. How the material is manufactured.