JPS6312912B2 - - Google Patents

Description

[Detailed description of the invention]

By adjusting the particle size of the raw material, this invention
The present invention relates to a method for producing high quality molded coke, particularly excellent hot properties, which are important properties of metallurgical coke. In recent years, as a metallurgical coke manufacturing process, research has been conducted on molded coke manufacturing processes that aim to save resources, labor, and be pollution-free by utilizing non-slightly caking coal, making the process continuous, and closing the generated materials. Development is actively underway. Various methods have been proposed and several manufacturing processes have been developed. However, there is no process that is actually operating on a commercial basis as metallurgical coke. It has been proposed that one of the reasons for this is that the quality of molded coke, especially its hot properties, is inferior to that of current room furnace coke. In other words, the results of tests using molded coke in blast furnaces show that pulverization in the furnace is significant, resulting in poor ventilation and an increase in the coke ratio.
Hanging shelves, slips, etc. will cause obstacles to smooth blast furnace operation. The reason why molded coke has poor hot properties is that the main raw material is generally non-caking or slightly non-caking coal, so even if pre-treatment by molding is performed, the coke matrix and structure remain in the chamber. This is because it is inferior to furnace coke. In other words, molded coke uses a large amount of non-slightly caking coal that is difficult to soften and melt during carbonization, so it has an inferior matrix compared to room furnace coke, and also has a molten bond (indoor furnace coke) in which coal particles melt and bond with each other. In the case of coke, the bond between particles is weaker in hot conditions due to the stronger degree of contact type bonding in which particles come into contact with each other and bond together. As a result of conducting research to improve the hot properties of shaped coke, we discovered a method for producing metallurgical shaped coke with excellent hot properties by adjusting the pulverized particle size of raw coal within a specific range. I found it. Conventional coking coal for molded coke production is usually processed using an intermediate crusher such as an impeller breaker or hammer mill to reduce the raw material coal to 3mm or less to 1mm or less (74μ).
The powder used was one that had been crushed into pieces (about 10% of which were less than mm). In contrast, the method of the present invention uses a combination of an intermediate pulverizer such as an impeller breaker or a hammer mill and a pulverizer such as a ball mill or a vibration mill, or a pulverizer alone to process raw coal into particles with a particle size of 1.5 mm or less and 74 μm or less. It is characterized by using particles whose particle size has been adjusted so that the ratio is 20 to 60%. The details of the method of the present invention will be described below. As a result of basic research on the pulverized particle size of raw material coal for molded coke production, the following facts were discovered. (1) By making the grain size of coal finer, the coke structure can be improved by giving the molded coke a homogeneous network structure, and we also compared the components with caking properties (caking coal and various bituminous materials) that soften and melt during carbonization. Even if a large amount is blended, phenomena such as blistering and fusion of the briquette coal during carbonization are reduced, so the coke matrix can be improved by increasing the content of these viscous components, and as a result, the properties of the briquette coke ( In particular, it was found that the hot properties were significantly improved.
In this case, the maximum particle size is preferably 1.5 mm or less, and if it is larger than that, the quality of the molded coke will deteriorate due to increased structure heterogeneity and blistering during carbonization. (2) On the other hand, if the coal particle size was made finer than necessary, the strength of the briquette coal became too weak, which caused damage to the briquettes, which hindered the carbonization operation, and also deteriorated the properties of the molten coke. The cost of pulverizing coal will also rise significantly. (3) Highly fluid caking substances (lime with a maximum fluidity of 10,000 ddpm or more as measured by a Gieseler plastometer, pitch (coal-based and petroleum-based), coal-based solvent-refined coal, etc.) are used as the caking component to be added in (1). If the amount of bituminous coal is small, it is preferable to grind it more coarsely than the main raw material coal because it is effective in reducing the deterioration of the properties (strength) of the briquette coal. However, if too large a quantity is added, although the properties of the briquette improve, the swelling and fusion of the molten coke become large, which may impede the carbonization operation. The particle size of the highly fluid caking substance is 100% below 1.5 mm using an intermediate pulverizer such as an impeller breaker.
It has been found that 20% or less of 74 μm or less is preferable; if it is coarser than this, it will have an adverse effect on the quality of the molded coke, and if it is finer than this, it will be less effective in reducing the deterioration of the molded coal properties (strength). Currently, industrial production of briquette coal is mainly carried out using double roll molding machines. Molded coal and molded coke were produced from raw materials with various coal particle sizes using a double roll molding machine, and the properties of each were investigated. Figure 1 shows an example of the relationship between the pulverized particle size and the properties of molten coal when the raw material is first pulverized to 100% of 1.5 mm or less using an impeller breaker, then further pulverized using a ball mill, and the ratio of 74 μm or less is varied. The quality of briquette coal is crushing strength 100.
Kg or more and trommel strength of 8.5% or more, we have confirmed that there will be no trouble in handling the coal briquettes due to breakage during the carbonization process, so we aimed to secure a trommel strength of 8.5% or more. From Figure 1, satisfactory briquettes were obtained when the particle size of the pulverized coal was 100% below 1.5 mm and 60% below 74 μm, but when the particle size of 74 μm or below exceeded 60%, the strength of the briquette suddenly decreased. It was found that the value gradually decreased. FIG. 2 is an example showing the relationship between the pulverized particle size of raw coal and the properties of molded coke. The finer the particle size of the raw coal, the better the properties of the molded coke. In particular, it can be seen that the strength improves markedly after the reaction with CO ₂ , which is an indicator of the hot properties of coke. Combining the above results, the appropriate range for the pulverized particle size of the raw material for molded coke production is 100% of 1.5 mm or less, and
It has been found that it is preferable to adjust the thickness to 74 μm or less in a range of 20 to 60%. That is, if the raw material is made coarser than this appropriate range, the properties of the formed coke, especially the hot properties, will be poor and the quality of the coke for metallurgical use will not be sufficient.
If it is made finer than the appropriate range, the properties of the briquette will deteriorate, causing troubles such as breakage of the briquette, and at the same time, the properties of the briquette coke will also deteriorate. In addition, the cost of grinding raw materials will increase significantly. Specific examples of the method of the present invention will be described below. Example 1 A coal blend of 65% non-slightly caking coal and 35% caking coal was first pulverized to 1.5 mm or less using an impeller breaker, and then further pulverized using a ball mill to adjust the particle size so that about 40% was 74 μm or less. . 8% soft pitch was added as a binder to raw coal whose particle size had been adjusted, and the mixture was kneaded while blowing in steam to produce briquette charcoal using a double roll molten machine.
For comparison, the impeller breaker is 1.5mm.
Molten coal was produced in the same manner using raw coal that was only pulverized. Table 1 shows the particle size of the raw material and the strength of the briquette coal.

[Table] Although the strength of the briquette charcoal produced by this method is lower than that of comparative briquette coal, it can withstand carbonization work. Next, using these briquettes as a heating medium and a mixture of coke oven combustion gas and high-temperature nitrogen gas, the center temperature of the briquettes was raised to approximately 1000 in 4.5 hours.
Molded coke was produced by carbonization at ℃. Table 2 shows the properties of molded coke.

[Table] It can be seen that the strength of the molded coke produced by this method is higher than that produced by the conventional method (comparative molded coke), and the strength after the CO ₂ reaction, which is an indicator of hot properties, is particularly markedly improved. You can see that it is very large. Example 2 A coal blend of 65% non-slightly caking coal and 35% caking coal was first pulverized to 1.5 mm or less using an impeller breaker, and then further pulverized using a ball mill to reduce the particle size so that about 50% was 74 μm or less. Prepared. 10% soft pitch was added as a binder to raw coal whose particle size had been adjusted, and the mixture was kneaded while blowing in steam to produce briquette coal using a double-roll molten machine. For comparison, briquette coal was produced using the same method using raw material coal that was simply crushed to 1.5 mm or less using an impeller breaker. Table 3
shows the particle size of the raw material and the strength of the briquette coal.

[Table] Although the strength of the briquette charcoal produced by this method is lower than that of comparative briquette coal, it can withstand carbonization work. Next, using these briquettes as a heating medium, a mixture of coke oven combustion gas and high-temperature nitrogen gas is used.
Molded coke was produced by carbonization under conditions such that the center temperature of the coke reached approximately 1000°C in 4.5 hours. Table 4 shows the properties of the molded coke.

[Table] The molded coke produced by this method had high drum strength (DI ¹⁵⁰ ₁₅ ) and high strength after CO ₂ reaction. The comparative molded coke has a higher amount of pitch added than the comparative molded coke shown in Table 2, so the coke properties are improved, but the molded coke strongly fuses together during carbonization, making it difficult to carry out a smooth carbonization operation. It was difficult. On the other hand, the molded coke produced by this method could be carbonized smoothly. Example 3 65% non-slightly caking coal, 30% caking coal, and 5% solvent-refined coal
When blending non-slightly caking coal and caking coal, an impeller breaker is used to crush the coal to 1.5 mm or less.
It is further ground in a ball mill to adjust the particle size to about 50% of the particles being 74 μm or less. On the other hand, the solvent-refined coal was pulverized with an impeller breaker to 100% of 1.5 mm or less, and 18% of 74 μm or less, and then mixed with a blended coal of non-slightly caking coal and caking coal whose particle size had been adjusted, and used as a raw material for molding. Next, 8% soft pitch was added as a binder, and the mixture was kneaded while blowing in steam to produce briquette charcoal using a double roll molten machine. For comparison, non-slightly caking coal,
Molded coal was produced using the same method using raw materials that were simply pulverized to 1.5 mm or less using an impeller breaker after blending caking coal and solvent-refined coal. Table 5 shows the particle size of the raw material and the strength of the briquette coal.

[Table] Although the strength of the briquette charcoal produced by this method is lower than that of comparative briquette coal, it can withstand carbonization work. Next, using these briquettes as a heating medium, a mixture of coke oven combustion gas and high-temperature nitrogen gas is used.
Molded coke was produced by carbonization under conditions such that the center temperature of the coke reached approximately 1000°C in 4.5 hours. Table 6 shows the properties of the molded coke.

[Table] From this it can be seen that the strength of the molded coke produced by this method is higher than that of the molded coke produced by the conventional method (comparison molded coke), and that the strength of the coke produced by this method is particularly significant after the CO ₂ reaction, which shows a significant improvement in strength. In the comparative molded coke, some of the molded coke was fused during carbonization, which caused problems in carbonization work. Example 4 A coal blend of 65% non-slightly caking coal and 35% caking coal was first pulverized to 1.5 mm or less using an impeller breaker, and then further pulverized using a ball mill to adjust the particle size so that approximately 60% of the coal was 74 μm or less. did. Add 10% soft pitch as a binder to raw coal whose particle size has been adjusted, knead it while blowing steam, pre-form it with a roll press, and then feed the coarsely crushed raw material to a size of <15 mm to a double-roll molding machine and mold it. produced charcoal. For comparison, 10% soft pitch was added to raw coal that had just been crushed to 1.5 mm or less using an impeller breaker, and the mixture was kneaded while blowing in steam to produce briquette coal using a double-roll molding machine. Table 7 shows the particle size of the raw material and the strength of the briquette coal.

[Table] Although the strength of the briquette charcoal produced by this method is lower than that of comparative briquette coal, it can withstand carbonization work. Although the briquette charcoal of this method has finer raw material particle size than the briquette of Example 2, it has greater strength, so it is necessary to coarsen the granule of the raw material before feeding it to the double roll molding machine. It turns out that is preferable. Next, these briquettes were carbonized using a mixture of coke oven combustion gas and high-temperature nitrogen gas as a heating medium under conditions such that the center temperature of the coke reached approximately 1000°C in 4.5 hours to produce briquette coke. Table 8 shows the properties of the molded coke.

[Table] The molded coke produced by this method was found to have high drum strength (DI ¹⁵⁰ ₁₅ ) and high strength after CO ₂ reaction. The comparative molded coke has a larger amount of pitch added than the comparative molded coke shown in Table 2, so the coke properties are improved, but the coke fusion during carbonization is severe, making it difficult to carry out a smooth carbonization operation. It was difficult. On the other hand, the molded coke produced by this method could be carbonized smoothly. By adjusting the particle size of the raw material using this method as shown in the examples above, it was possible to obtain molded coke of high quality, particularly excellent hot properties, without interfering with the carbonization work.

[Brief explanation of the drawing]

FIG. 1 is a graph showing an example of the relationship between the degree of grinding of the raw material and the properties of molded coke, and FIG. 2 is a graph showing an example of the relationship between the degree of grinding of the raw material and the properties of formed coke.

Claims (1)

[Scope of Claims] 1. After preparing raw coal to have 100% of the raw material coal below 1.5 mm and 20% to 60% below 74 μm, a bituminous material such as coal tar, pitch, petroleum asphalt, etc. is added as a binder and molded. A molded coke production method characterized by high-temperature carbonization of molded coal. 2. After preparing raw coal to a particle size range of 100% of 1.5 mm or less and 20 to 60% of 74 μm or less,
A highly fluid caking substance (caking substance with a maximum fluidity of 10,000 ddpm or more on a Gieseler plastometer) whose particle size has been adjusted to 100% or less, 74 μm or less, and 20% or less is blended with coal tar, pitch, petroleum asphalt, etc. A molded coke manufacturing method characterized by high temperature carbonization of molded coal formed by adding bituminous material as a binder.