JPS6113517B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing high-quality metallurgical coke used in iron manufacturing etc. from raw material pulverized coal. In recent years, as a method for producing metallurgical coke, a so-called method for producing coke blended with briquette coal has been widely adopted. This briquette blended coke manufacturing method is
After adding a binder to the pulverized coal for briquette coal and heat-treating it, or without heat treatment, it is pressure-molded, and a portion of the resulting briquette coal is blended with raw material pulverized coal to make coke oven charging coal. It is carbonized in a furnace to produce metallurgical coke. In this way, when some briquette coal is blended into raw coal powder, the briquetting effect and the bulk density of the charged coal are improved, and the strength of the coke is also improved accordingly. It is generally known that non-slightly caking inferior quality coal can be blended into charged coal. However, in the conventional coke production method with briquette coal, as the blending ratio increases, the bulk density of the coal charged into the coke oven increases until a predetermined briquette blending ratio is reached. However, if the blending ratio of briquette coal exceeds a certain level, the space formed between the briquette coals will not be sufficiently filled with raw coal powder, and the bulk density of the charged coal will decrease. The strength of the coke produced deteriorates or does not improve. In other words, when charging coal with a briquette mixture is charged into a coke oven from a certain height, the relationship between the two is investigated using the charging bulk density on the vertical axis and the briquette blending ratio on the horizontal axis. If you look, there is a maximum value. The maximum value of this charging bulk density is determined by the dimensions of the coke oven, the particle size and particle size distribution of briquette coal, the particle size of raw coal powder,
Although it changes depending on the particle size distribution or the proportion of moisture contained in molded coal or powdered raw coal, it is measured and determined as a unique value by setting these fluctuation values to a constant value. The particle size of charcoal is 20 to 100 mm, and the particle size of raw coal powder is 3 mm or less.
When charging 70 to 90 wt% and water content to about 3 to 15 wt% in a normal coke oven, the charging bulk density reaches its maximum value within the range of briquette coal blending ratio of approximately 50 to 85 wt%. It is clearly recognized that even if the blending ratio of briquette coal is increased further, the charged bulk density does not increase but decreases, and the strength of the coke produced from this also decreases. Therefore, if the blending ratio of non-slightly caking poor quality coal contained in raw coal powder is constant, there is a limit to the strength of the coke produced even if the blending ratio of briquette coal is increased, and there is a limit to the strength of the coke produced from the coke oven. Due to the load involved when extruding the produced coke using an extruder, it was previously believed that the blending ratio of briquette coal was limited to about 30 wt%. By the way, as a method to prevent a decrease in the charging bulk density when the blending ratio of briquette coal is 35 wt% or more, a method of blending briquette coal having multiple types of particle sizes has been proposed (Japanese Patent Application Laid-Open No. 1983-1983). −133301). However, since this method uses briquette coal having multiple types of particle sizes, the manufacturing process becomes complicated, such as requiring multiple types of pressure molding machines and molds of different shapes. There is a problem in that the particle size of the briquette coal is discontinuous and the particle size ratio is small, so that it is difficult to expect much improvement in the charging bulk density such as closest packing. Therefore, in this method, even if the blending ratio of briquette coal is increased, the charging bulk density cannot be expected to improve and is slightly decreased, and the coke strength is also lower than that of 20 to 85wt% when the blending ratio of briquette coal is 20 to 85wt%. It is explained that it remains almost constant within the range of , and that no significant improvement can be obtained. Therefore, when charging coal with a briquette blend into a coke oven from a certain height, the present inventors charged the coal at a charging bulk density higher than the expected maximum charging bulk density. Various methods for charging coal into a coke oven were investigated. As a result, when blending briquette coal into powdered coking coal, if part or all of the powdered coking coal is replaced with pulverized briquette coal that has been pulverized to a particle size below a certain level in advance, it is surprisingly possible to reduce the Not only is there no decrease in the charging bulk density due to a high blend of briquette coal, but on the contrary, the charging bulk density is significantly improved, and the drum strength of the resulting coke and the strength after compact reaction CSR (%) are significantly improved. The present invention was completed based on the discovery that the particle size distribution was greatly improved, and more importantly, the ratio of intermediate particle size distribution between 25 and 75 mm was increased, which was an unexpected effect of particle size distribution. be. That is, the present invention adds a binder to powdered coal for molded coal to produce molded coal under pressure to a predetermined particle size, blends the molded coal with raw coal powder to prepare coke oven charge coal, In the method of producing coke by carbonizing this charged coal in a coke oven, the blending ratio of the briquette coal is in the range of 40% to 85% by weight, and part or all of the coking coal powder is preliminarily added to the briquette coal. It is characterized in that it is replaced with pulverized briquette charcoal that has been pulverized so that it has a particle size of 1/4 or less of the particle size and has a continuous particle size distribution. In a particularly preferred specific embodiment of the present invention, briquette coal is blended up to the blending ratio of briquette coal at which the bulk density of the charged coal reaches its maximum value when only briquette coal is blended with the powdered raw coal. , to replace part or all of the remaining raw material pulverized coal with pulverized briquette coal, which would reduce the expected charging when charging coal with a briquette blend into a coke oven from a certain height. Charging coal can be charged into a coke oven with a bulk density higher than the maximum value of the bulk density, and the coke strength is improved and the granulation effect becomes remarkable. Moreover, to express a particularly preferred embodiment of the present invention in more concrete numbers, 40 wt% or more, preferably 50 to 85 wt% of the charging coal for a coke oven is blended with briquette coal, and the remaining powdered coking coal is blended with molten coal. Part or all of the coal is replaced with pulverized briquette coal that has been pulverized in advance to have a continuous particle size distribution of 1/4 or less of the particle size of the briquette charcoal. As a result, the bulk density of the coke oven charging coal obtained is significantly improved, and the coke strength is also significantly improved and the granulation effect is significantly improved. In the present invention, the pulverized coal for briquette coal, pulverized coking coal, and pulverized pulverized coal for pulverized briquette coal are ordinary charging coal for coke ovens, or ordinary charging coal for coke ovens for producing coke for blast furnaces. contains 10wt% or more of non-slightly caking inferior quality coal, which is considered unsuitable.
Or a mixture of 1wt% or more of coke powder, pitch coke, petroleum coke, tar slag, etc., each singly or in combination, with a particle size of 3 mm or less.
It is used after being crushed to about 70-90wt%.
Each of these can be used alone, but
It is also possible to use a premixed mixture at a certain ratio. The above-mentioned normal coke oven charging coal has a volatile content of 25 to 35% and CSN (JIS M8801, 4).
Crucible expansion test method) is in the range of 3 to 9, and
Drum strength when coked in a practical coke oven (JIS K2151, 6.2 drum test method)
Charging coal for blast furnace coke production obtained by blending and adjusting any coal so as to have a DI ^{of 150} ₁₅ 80 or more may have a property range conventionally known. In addition, non-slightly caking inferior quality coal has a CSN of 0 to 2, a fluidity index [JIS M8801, 5 fluidity test method (Gieseler plastometer method)] of 0 to 10, and a total expansion index of 0 (Audaiber Arneux method). This coal is considered unsuitable for producing coke for blast furnaces due to its characteristics. Further, in the present invention, a coal-based or petroleum-based bituminous material is used as a binder used when producing briquette coal or pulverized briquette coal. Suitable coal-based bituminous materials include, for example, coal-based pitch, road tar, coal solvent extracts or their residues, coal-based heavy oil, etc.; Pituchi, Asphalt,
Petroleum heavy oil or those obtained by heat treatment or solvent extraction treatment of petroleum heavy oil or the like are suitable. Molded coal in the present invention is obtained by adding a binder to powdered coal for molding, mixing it, and then applying appropriate heat treatment or pressure-molding it to a predetermined particle size using a molding machine without heat treatment. Yes, and although there is no particular limitation, the particle size of briquette coal should be 20
It is advantageous to set it to about 100 mm. Molded coal may be partially crushed during transfer to a coke oven or during coal charging, but these are treated as molten coal. Further, the pulverized briquette coal in the present invention is produced by adding a binder to pulverized charcoal for pulverization briquette coal to produce briquette coal, and pulverizing the briquette coal with a crusher. As for the crushing method at this time, it is convenient to use a double roll crusher with an adjustable gap.In particular, the molten coal is charged into a double roll crusher that leaves a gap of a predetermined particle size. death,
It is advantageous to use one or more passes to grind the particles so that they have a continuous particle size distribution with the largest particle size in the gaps. In the present invention, raw coal, powdered coal for briquette coal, and pulverized coal for pulverized briquette coal may have the same coal composition or may have different coal compositions, or may have different coal compositions. The binder and the binder for pulverized and shaped coal may have the same composition, or may be different. In the present invention, while blending the briquette coal as it is is preferable in terms of improving the charging bulk density and coke strength, it is preferable that the blending ratio of the briquette coal is within a certain range or above. It is most preferable to replace part or all of the raw material pulverized coal with pulverized briquette coal, taking into account that the bulk density of the charging material is at its maximum value, and that a blending ratio higher than this will result in a decrease in the bulk density of the charging material. It is something. In addition, the charging bulk density is also influenced by the particle size ratio between the particle size (dc) of the briquette coal and the particle size (df) of the crushed and added pulverized briquette coal. For example, ASTMD291
As a result of investigating the relationship between dc/df and charging bulk density when 40 wt% of pulverized briquette coal of different particle sizes was blended with 60 wt% of the briquette coal of the example described below using the -60 method, as shown in Figure 1, It was found that the increase in charging bulk density slows down when dc/df is 4, and is almost saturated when dc/df is 7.5 or higher. Therefore, it is appropriate that the particle size of the pulverized briquette coal be 1/4 or less, preferably 1/7 or less of the briquette particle size, and further, by adding pulverized briquette coal that has a continuous particle size distribution. It was found that closer packing becomes possible. Hereinafter, the present invention will be explained in more detail based on examples. (1) Test furnace and operating conditions The prepared charge coal was dropped from the charging port into a gas-heated 1/4 ton coke oven and carbonized at a fuel temperature of 1300°C. (2) Preparation of powdered raw coal Non-slightly caking inferior quality coal (brand name Witbank)
16 types of coking coal containing 12.0wt% were blended and pulverized so that when sifted through a 3 mm sieve, the sieve content was 87.6wt%, and the moisture content was adjusted to approximately 10% to produce powdered coking coal. The strong viscosity ratio of this powdered raw coal is 52%.
The volatile content is 29.4wt%, and the bulk density when charged into the test furnace is 629Kg/ ^m3 . (3) Preparation of briquette coal Add 6wt% of coal-based soft pitch with a softening point of 35℃ to the above powdered coal as a binder, mix, knead under heat, and use a double roll press at a molding pressure of 4t to 45mm x 45mm x It was pressure molded into a masset shape with a size of 26 mm. The apparent density of this briquette coal is
It was 1.15g/ml. (4) Preliminary experiment using conventional method Charging coal was prepared by blending raw coal powder and briquette coal in various proportions, and this charging coal was charged into the above test furnace to produce coke. Table 1A shows the results of investigating the charging bulk density, drum strength of the coke produced (DI ¹⁵⁰ ₁₅ ), particle size yield of 25 to 75 mm of the coke produced, strength after small size reaction, and coke productivity ratio.
It was as shown in the group. The strength after small scale reaction was determined by the following test method. That is, 200 g of sample coke prepared to a particle size of 20 ± 1 mm was reacted in a reaction tube at 1100 °C ± 10 °C for 2 hours under CO ₂ flow at 5/min, and the weight after the reaction was taken as Ag. After the reaction, all the samples were transferred to the drum (130φ x 700mm) of a type I tester.
^{After rotating the sample for 20 Ypm x 30 minutes, the sample is sieved, and the weight of the +10 mm portion is taken as Bg, and the small reaction strength CSR 600 10} _in this case is calculated using the following formula _:
It was determined by B/A x 100%. In addition, the coke productivity ratio was determined using the following formula. Coke productivity ratio = Coke generation time when briquette charcoal is not added / Coke generation time when briquette charcoal is blended × Amount of coke residue when briquette charcoal is blended / Amount of coke residue when briquette coal is not blended Also, the molding at this time The relationship between the charcoal blending ratio and the charging bulk density is shown by the dotted line in Figure 2, and the relationship between the briquette coal blending ratio and the drum strength (DI ¹⁵⁰ ₁₅ ) of the coke produced is shown by the dotted line in Figure 3. The relationship between the ratio and the particle size yield of 25 to 75 mm of produced coke is shown by dotted lines in FIG. 4, respectively.

[Table] As a result of this preliminary experiment, the charging bulk density is as shown in Table 1 and Figure 2, when the blending ratio of briquette coal is 60~
It shows the maximum value at 80wt%, and when the content is higher than this, the charging bulk density clearly decreases. Further, as shown in Table 1 and FIG. 3, the drum strength (DI ¹⁵⁰ ₁₅ ) of the produced coke reaches its maximum value when the blending ratio of briquette coal is 60 to 80 wt%, and decreases above this. Furthermore, the particle size yield of the produced coke of 25 to 75 mm reaches a maximum value of 60.0% when the blending ratio of briquette coal is 60 wt%, and clearly decreases when the blending ratio is higher than this. In addition, the productivity ratio and the strength after small-sized reaction of coke produced
CRS (%) reached its maximum when the briquette coal blending ratio was 100wt%. (5) Example 1 The present invention was carried out as follows based on the above preliminary experiment. That is, assuming the briquette coal particle size is 45 mm,
The distance between rolls is set to 6 so that dc/df=7.5.
pulverized briquette coal with a double roll crusher to prepare pulverized briquette coal having a continuous particle size distribution of 6 mm or less as shown in Group B of Table 2,
Based on 60wt% of briquette coal, some or all of the powdered raw coal is crushed to 10wt% or 20wt of briquette coal.
%, 30wt%, and 40wt% to prepare charging coal, and charge this charging coal into a test furnace under the same conditions as in the preliminary experiment to produce coke. Bulk density, drum strength of produced coke (DI ¹⁵⁰ ₁₅ ), strength CSR after small size reaction (%),
The 25-75mm particle size yield and coke productivity ratio were investigated. The results are shown in Group B in Table 1, and
The solid line in Figure 2 shows the relationship between the blending ratio of pulverized briquette coal and the charging bulk density, and the relationship between the blending ratio of pulverized briquette coal and the drum strength (DI ¹⁵⁰ ₁₅ ) of the produced coke is shown in Figure 3. The solid line in FIG. 4 shows the relationship between the blending ratio of pulverized briquette coal and the particle size yield of 25 to 75 mm in coke produced. In this Example 1, the charging bulk density is
As shown in the table and Figure 2, as the blending ratio of pulverized briquette coal increases, the value increases even more significantly than the maximum value for briquette coal alone, and the degree of improvement increases linearly. As shown in Table 1 and Figure 3, the drum strength of the produced coke is also significantly improved when the sum of the blended ratio of briquette coal and the blended ratio of pulverized briquette coal is 70wt% or more. The particle size yield is also the first
As shown in the table and FIG. 4, there is a remarkable improvement, and the productivity ratio of coke produced and the strength CSR (%) after small-sized reaction also improve almost linearly. (6) Example 2 Similar to Example 1, the experiment was carried out based on the above preliminary experiment. In this Example 2,
The distance between the rolls is 3mm so that dc/df=15.
The briquettes were pulverized using a double-roll crusher, as shown in Group C of Table 2, to prepare pulverized briquettes having a continuous particle size distribution of 3 mm or less. , drum strength of produced coke (DI ¹⁵⁰ ₁₅ ), strength after small scale reaction CSR
(%), particle size yield of 25 to 75 mm, and coke productivity ratio were investigated and shown in Table 1, Group C. In addition, the relationship between the blending ratio of pulverized briquette coal and the charging bulk density, the relationship between the blending ratio of pulverized briquette coal and the drum strength (DI ¹⁵⁰ ₁₅ ) of the produced coke, and the relationship between the blending ratio of pulverized briquette coal and the drum strength of the produced coke, The relationship with the grain size yield of 25 to 75 mm is shown by dashed lines in FIGS. 2, 3, and 4, respectively. In this Example 2, compared to the case of Example 1, as shown in Table 1, Figure 2, and Figure 4, the grain size yield of 25 to 75 mm was slightly decreased. Bulk density and productivity ratio, drum strength of produced coke (DI ¹⁵⁰ ₁₅ ) and strength after small size reaction
There has been some improvement in CSR (%).

[Table] In the above example, the blending ratio of briquette coal was 60wt.
I showed an example based on %, but this is 1/4t
This is because the charging bulk density in the test furnace and when the molten coal particle size was 45 mm was almost the maximum value.
However, even if the base of briquette coal is within the range of 50 to 85 wt%, the charging bulk density, coke strength, and
There is no change in the effect of improving mm particle size yield, and the present invention can naturally be carried out advantageously. As can be understood from the above examples, according to the method of the present invention, when blending briquette coal into pulverized raw coal, part or all of the pulverized raw coal is replaced with pulverized briquette coal that has been crushed in advance. In this case, the voids formed between the briquettes are densely filled with the pulverized briquette coal and the raw material pulverized coal, which have a continuous particle size distribution, and the bulk density of the charged coal is significantly improved. This also applies when briquette coal is crushed.
This is because it is considered that this pulverized briquette coal still maintains the molding effect due to the kneading and pressure bonding action of the binder during the molding of the briquette coal.
Therefore, by replacing part or all of the raw material pulverized coal with this pulverized briquette coal, the bulk density of the charged coal can be significantly increased compared to the conventional case where only briquette coal and raw material pulverized coal are used. It is thought that the molding effect has also been significantly improved. In this way, by improving the bulk density of the charged coal, the drum strength (DI ¹⁵⁰ ₁₅ ) of the produced coke also increases almost proportionally, making it possible to produce high-quality metallurgical coke. It became. For this reason, the drum strength (DI ¹⁵⁰ ₁₅ ) of the coke produced is improved over the drum strength of coke produced by the conventional method, and a larger amount of cheap inferior coal or coke powder, pitch coke, or petroleum coke is used. Even if large amounts of coke, tar slag, etc. are used, metallurgical coke can be produced that has the same drum strength as conventional products. In addition, in this way, a large amount of non-slightly caking inferior quality coal, coke powder, pitch coke,
By blending petroleum coke, tar slag, etc., the expansion of the charged coal that is carbonized in the coke oven will be reduced, which will reduce the extrusion load when extruding the coke produced in the coke oven using the extractor. The sum of the blending ratios of briquette charcoal and pulverized briquette coal can be dramatically increased. Furthermore, by adding pulverized briquette coal, it is possible to increase the overall briquette blending ratio, and as a result, the interval between charged coal particles can be narrowed, or in other words, the bulk density of the charged coal can be reduced. This can improve the hot properties of the produced coke and the volume balance between the charged coal and the produced coke, and as shown in Table 1, it also significantly improves the productivity ratio of the produced coke. be able to. Furthermore, when looking at the particle size distribution of the metallurgical coke produced by the method of the present invention, the particle size distribution of the produced coke is 25 to 75% compared to that in preliminary experiments using the conventional method.
The millimeter particle size yield has been significantly improved, which is extremely beneficial for blast furnace operation. This particle size yield also shows almost the same tendency as the charging bulk density, and is considered to be a result of the improved charging bulk density in the present invention. Therefore, the present invention makes it possible to produce high-quality coke with a high blend of molten coal, and is useful for effectively utilizing non-slightly caking inferior quality coal, fine coke, tar slag, etc., and for saving high-quality caking coal that is difficult to obtain. etc., are extremely useful industrially.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between dc/df and bulk density, Figure 2 is a graph showing the relationship between briquette coal blending ratio and charging bulk density, and Figure 3 is a graph showing the relationship between briquette coal blending ratio and drum of produced coke. A graph showing the relationship between strength and strength.
It is a graph showing the relationship with particle size yield.

Claims (1)

[Claims] 1. A binder is added to pulverized coal for briquette coal to produce briquette coal that is pressure-molded to a predetermined particle size, and the briquette is blended with raw material pulverized coal to prepare coal for coke oven charging. In the method of producing coke by carbonizing this charged coal in a coke oven, the blending ratio of the briquette coal is in the range of 40% to 85% by weight, and part or all of the coking coal powder is preliminarily added to the briquette coal. A method for producing high-quality coke, characterized by replacing the coke with pulverized briquette coal that has been pulverized to have a particle size of 1/4 or less and a continuous particle size distribution. 2. The claim set forth in claim 1, characterized in that the briquette coal is blended up to the blending ratio of the briquette coal at which the inserted bulk density of the charged coal shows the maximum value when only the briquette coal is blended with the powdered raw coal. A method for producing high-quality coke.