JP3388014B2 - Coke reforming method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of converting coke charged alone or together with sinter during blast furnace operation into coke having excellent gasification reactivity, that is, high reactivity. The present invention relates to a method for modifying coke and a method for producing a multi-layer coke having different reactivities on the surface and central portion of lump coke. 2. Description of the Related Art In a blast furnace operation, sinter and coke as charges are charged alternately. In the furnace the charge is deposited in layers,
At high temperatures, coke is gasified by an oxidizing gas, and the sintered ore generates metallic iron by reaction with the reducing gas and gradually falls. In recent years, a technology to reduce the fuel ratio by mixing and charging 10-25 mmφ coke into sinter and improving the reduction efficiency in the 700-1200 ° C region in the blast furnace has been developed. Incorporated. [0003] Further, by increasing the reactivity of coke to gasification, the reduction efficiency in the blast furnace can be improved, and the total fuel ratio can be reduced. When a multi-layered coke (that is, a coke lump surface (having a dimensionless radius of about 0.9) has high reactivity and the inside has a high strength) is used, the coke function in the blast furnace causes 700-1200 ° C. in the blast furnace. In the area of, it shows high reactivity and can enjoy the advantage of reducing the fuel ratio by improving the reduction efficiency,
In the lower part of the furnace, the highly reactive part of the surface is consumed by the reaction,
Since the residual central coke has a high strength, the generation of coke powder that inhibits stable operation is suppressed. [0005] The most important properties conventionally required for metallurgical coke are cold strength and hot strength. In order to obtain such high strength coke, the degree of coalification is appropriately high and 400
Raw coal that exhibits fluidity in the temperature range of 〜500 ° C. is selected. Since these raw coals once pass through a liquid phase, the lamellar arrangement is promoted and the gasification reactivity of the coke carbonaceous material after solidification is reduced. A method of producing highly reactive coke by dry distillation using raw coal is disclosed in Japanese Patent Application No. 4-291450, in which a large amount of non-coking coal or coking coal is blended into coking coal or a catalyst is added. is there. However, sufficient strength has not been obtained. Factors governing the coke gasification reactivity include: Coke carbonaceousness 2. Specific surface area of coke
3. It is a catalyst. [0008] Measures for controlling the coke gasification reactivity include 1) a method of selecting raw coal and a method of carbonization and 2) a method of reforming the produced coke. Normally, the reactivity of metallurgical coke is expressed by CRI (the amount of gasification reaction when 200 g of coke is reacted with carbon dioxide gas at 1100 ° C. for 2 hours) and is about 30 or less. It refers to coke that has a higher value than the CRI of metallurgical coke. [0010] Measures 1) for controlling the gasification reactivity by carbonizing coal are as follows. Carbonaceous structure,
And 2. 2. The specific surface area is almost determined by the properties of the raw material coal. Of the catalyst. Conventionally, coke produced in a coke oven requires a cold or hot strength, which is the most important property in using a blast furnace. An increase in strength necessarily accompanies a decrease in reactivity, and an increase in reactivity lowers the strength. As a method of obtaining a highly reactive coke by adjusting the blending of coal, there is a coke production method in which a large amount of non-caking coal and finely caking coal is blended, a binder and the like are kneaded, press-molded and dry-distilled. It is conceivable that a kneader, a press molding machine, or a special dry distillation furnace is required for adding the binder. [0013] Further, multilayer coke is not currently produced in any of the furnace type coke production method and the molded coke production method. As a method 2) for controlling the gasification reactivity of the coke that has already been generated, there is a method using high-temperature steam treatment, but an apparatus for performing steam treatment is required. In addition, when used in an actual blast furnace, it is necessary to perform mass production, which is a major cause of raising the production cost and is industrially difficult. Therefore, it is desirable to use a method of attaching and adding a catalyst. As a conventional technique, there is a method of improving the reactivity by dry distillation of a catalyst together with raw coal, but there is no technique for increasing the reactivity by attaching or adding the catalyst to coke. As a catalyst for improving the reactivity of coke, there are transition metals such as alkali, alkaline earth element, iron and nickel. These catalysts are expensive potassium salts in the case of potassium, slaked lime, quick lime in the case of calcium, Calcium salts are added. In addition, as a method for adding a catalyst to coke that has already been produced, seawater that requires secondary treatment (drying) is sprayed. However, the production cost of high-reaction raw coke and multi-layer coke is greatly increased because they are used in large quantities in a blast furnace. When iron ore is attached to red hot coke,
When the coke mass is large, the surface pore structure changes due to carbon consumption by the reaction of Fe ₂ O ₃ + 2C = FeO + 2CO, and Fe remains on the coke mass surface as a gasification reaction catalyst in the pore structure. Thereby, the coke reactivity can be multi-layered. On the other hand, the coke particle size is small (for example, 10 to 30 mm)
In the case of, the whole mass shows high reactivity. The red heat means the coke temperature when the coke is discharged from the carbonization furnace, and varies depending on the coke oven temperature.
It has a width of 200 ° C. SUMMARY OF THE INVENTION The present invention relates to a case where a catalyst containing the above-mentioned cost-increasing factor is used, as an alternative, to powdery iron ore generated in a steelworks or to discharge from each process of a steelworks. The purpose is to make effective use of low-value collected powdery materials such as dust. Further, in the conventional method of improving reactivity by adding a catalyst to raw coal, the effect of improving reactivity is recognized, but the strength is reduced. Furthermore, the production of multi-layer coke is not possible. [0020] In order to solve the above-mentioned problems, the gist of the present invention is to provide powdered iron ore from 0.2% by weight to 25% by weight of red hot coke or coke cooled to room temperature. The purpose is to improve the reactivity of coke by adhering or adding 0.2% to 30% by weight of a powdery recovered substance generated in each process in a steel mill. Here, as the powdery collected matter generated in each process in the steel mill, for example, dust generated and collected from a sintering machine, a blast furnace or a converter is used. The term “powder” is defined as a particle diameter of 500 μm or less. In order to improve the gasification reactivity of coke, first, powdery iron ore generated in a steelworks as a catalyst and dust discharged from each process in the steelworks are attached and added to coke at room temperature. When the gasification reactivity was measured, it was found that the coke gasification reactivity could be controlled. Further, after adding and adding red hot coke fine iron ore produced and discharged by a small carbonization test apparatus, the reactivity of the cooled coke was measured. And the center maintained its conventional reactivity. That is, multilayering of gasification reactivity was recognized. In order to use the present coke in an actual blast furnace, a large amount of processing is required, and it is desirable that the coke be performed in an actual coke oven line. As a method of producing the above-mentioned highly reactive coke and multi-layer coke in a coke production line, when collecting red hot coke from a coke guide to a CDQ bucket,
Spraying and attaching powdered iron ore and steel mill dust. In addition, when entering the interior of the CDQ device, it is desirable to perform treatment in the cooling chamber above the CDQ device, and it is conceivable to add a gasification reaction catalyst through a nozzle installed above the CDQ device. Also adhere at warm and room temperature,
As a method of addition, by mixing and adhering with the powdery recovered material before the coke cutter in the coke sizing process, the product coke and the surplus powdery recovered material are separated. CRI by adhering and adding fine iron ore or powder generated in steelworks to red hot coke and cold coke
The effect of this is the catalytic effect of iron, calcium, potassium, sodium, etc., present in the additive that has penetrated into the micropores on the coke surface, and the diffusion of the reaction gas due to the increase in the reaction interface area that progresses during the gasification reaction. Due to improvement in performance.
In addition, when added to red-hot coke, this is due, in addition to the above reasons, to an increase in the coke reaction interface due to the adhesion and reduction reaction of iron at the time of addition. In the case of a two-layer coke, the above-mentioned effect of improving the reactivity is limited to the surface of the coke lump, and in the blast furnace, the highly reactive surface portion is consumed as it descends to the lower part of the furnace. The maximum adhesion amount at room temperature was 25% by weight for powdered iron ore and 30% by weight for recovered dusts. That is, in order to improve the reactivity, the amount that can be deposited to maximize the effect is 25% by weight of fine iron ore and 30% by weight of dust based on the weight of coke. Further, the addition amount necessary for exhibiting the catalytic effect is 0.2%. EXAMPLE An example in which powdery iron ore and dust generated in an ironworks are added to coke and added to improve gasification reactivity will be described below. 1) In order to improve the gasification reactivity of coke, small coke (13 to 18 mm
φ) Two types of iron ore pellet feeds (particle size: 200 μm or less) with the composition shown in the table are attached as additives to the surface
I was measured. The CRI reactivity was increased by 10 or more in the case where the fine iron ore was not attached and the case where the iron ore was attached. [Table 1] The composition of the added iron ore is as follows. [Table 2] 2) In order to improve the gasification reactivity of coke, small coke (13 to 18 mm) produced in an actual furnace was used.
φ) Two types of dust (particle size: 5 μm or less) recovered in an ironworks having the composition shown in the table as additives were attached to the surface, and the CRI was measured. C when the collected dust does not adhere and when it adheres
RI reactivity increased by about nine. [Table 3] The composition of the added dust is shown below. [Table 4] 3) FIG. 1 shows the relationship between the amount of iron added and the CRI when two types of coke (porosity of 49% and 53%) with different porosity and the amount of powdered iron ore were changed and CRI was measured. Is shown. The gasification reactivity increases with an increase in the amount of powdered iron ore, but tends to be saturated. In the case of coke with high porosity, ΔCRI is slightly higher even with the same amount of deposition, but this is because fine iron ore is effectively attached as a catalyst due to the large surface area of the lump surface of coke with high porosity. It is considered a thing. The adhesion amounts of Examples 1), 2) and 3) are as follows. In the case of room temperature coke, coke and an additive twice as much as the weight of coke are taken in a container, mixed well, and adhered. Then the excess additives are sieved off,
The coke on the screen was used as modified coke. 4) Fine iron ore A was sprinkled from the upper portion onto the red hot coke discharged when the carbonization chamber central temperature reached 1100 ° C. by carbonization in a small coke carbonization furnace to produce multilayer coke. After cooling, the large lump coke was pulverized into 10 mm or less coke powder and 10 mm or more lump coke produced after 600 rotations with a drum-type rotary wear strength measuring device, and the gasification reaction rate was measured by a thermobalance. The measuring method is as follows. 100 mg of ground coke is collected,
100 at 10 ° C / min in an air flow of 150 ml / min of nitrogen
The temperature is raised to 0 ° C., and then the carbon dioxide gas is switched to 150 ml / min, and the weight loss due to solution loss is measured. The results are shown. [Table 5] The reactivity of the coke breeze produced from the surface of the coke lump is 2.3 times that of the lump coke, and the reactivity is clearly multi-layered. According to the present invention, a conventional method is provided in which powdery ore such as powdery iron ore generated in a steelworks or dust discharged from each process in a steelworks is attached to and added to coke. Its industrial value is that it dramatically improves the reactivity of coke, makes it possible to produce two-layer coke that could not be produced, and makes effective use of low-usability steelworks. Is big.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing the relationship between the amount of adhering fine iron ore to coke having different porosity and coke gasification reactivity.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-228428 (JP, A) JP-A-59-96203 (JP, A) JP-A-5-302106 (JP, A) JP-A 52-228 59001 (JP, A) JP-A-60-262907 (JP, A) JP-A-52-107213 (JP, A) JP-B-52-43169 (JP, B2) (58) Fields investigated (Int. ⁷ , DB name) C10B 57/04-57/06 C21B 5/00

Claims (1)

(57) Claims: 0.2% to 25% by weight of powdered iron ore is added to red hot coke or coke cooled to room temperature;
Alternatively, the powdery material generated in each process in the steel works is reduced to 0.
A coke reforming method characterized in that 2 to 30% by weight is added or added.