KR20130059429A - Method for producing metallurgical coke - Google Patents

Abstract

This invention uses the coal briquettes which accurately evaluated the softening melting characteristic of the coal used for a coal mixture by measuring the softening melting characteristic of coal in the state which simulated the environment of the softening molten coal in the coke oven. It is to provide a method for producing a metallurgical coke having higher quality such as strength. Using each coal and caking additive constituting the blended coal as a sample, a predetermined amount is filled in a container, a material having through holes on the upper and lower surfaces is disposed on the sample, and a constant load is applied to the material having the through holes on the upper and lower surfaces. The sample is heated at a predetermined heating rate, the penetration distance of the sample penetrated into the through hole is measured in advance, and in part or all of the coal and the caking additive having a penetration distance higher than the predetermined management value, in an oxygen-containing atmosphere, It is made to weather by normal temperature or heat processing, and it mix | blends after reducing a penetration distance, and the manufacturing method of metallurgical coke is used.

Description

Manufacturing method of metallurgical coke {METHOD FOR PRODUCING METALLURGICAL COKE}

This invention uses the test method which evaluates the softening melting characteristic at the time of coal distillation with high precision, The manufacturing method of the metallurgical coke which can reduce the usage of high quality coal, maintaining coke strength, or from the same coal It relates to a method for producing metallurgical coke from which coke can be obtained.

Coke used in the blast furnace method which is most commonly performed as a steelmaking method plays the role of a reducing material, a heat source, a spacer, etc. of iron ore. In order to operate blast furnace stably and efficiently, it is important to maintain the air permeability in blast furnace, and manufacture of coke with high intensity | strength is calculated | required. Coke is pulverized and manufactured by mixing the mixed coal which mix | blended the various coke-making coals which adjusted the particle size in coke oven. Coking coal is softened and melted at a temperature range of about 300 ° C to 550 ° C in dry liquor, and at the same time, foamed and expanded with the generation of volatile matters, thereby adhering the respective particles to each other to form a lump-shaped semicoke. do. The semi-coke is then solidified by shrinking in the process of raising the temperature to around 1000 ° C., resulting in solid coke. Therefore, the adhesive property at the time of softening melting of coal has a big influence on the properties, such as coke strength and particle size after dry distillation.

Moreover, the method of manufacturing coke by adding the caking additive which shows high fluidity | liquidity in the temperature range where coal softens and melts to a coal blend is aimed at strengthening the adhesion of the coal (coal coal) for coke manufacture. Here, a caking additive is tar pitch, a petroleum pitch, a solvent refined coal, a solvent extraction coal, etc. specifically ,. Similarly to coal, the adhesive properties at the time of softening and melting of these caking additives have a big influence on the coke property after distillation.

As mentioned above, the softening and melting characteristics of coal are extremely important because they greatly influence the coke properties and the coke cake structure after drying, and the measurement method has been actively studied for a long time. Particularly, the coke strength, which is an important quality of coke, is greatly influenced by the coal characteristics, especially coal conversion and softening and melting characteristics. The softening melting characteristic is a property which softens and melts when heating coal, and is usually measured and evaluated by fluidity, viscosity, adhesiveness, expandability, etc. of the softening melt.

As a general method of measuring the fluidity at the time of softening melting among coal softening melting characteristics of coal, the coal fluidity test method by the Gieseler plastometer method prescribed | regulated to JISM 8801 is mentioned. The gaseous plastometer method puts coal pulverized to 425 μm or less into a predetermined crucible, heats it at a prescribed heating rate, reads the rotational speed of the stirring rod with the prescribed torque, and reads the scale with ddpm (dial division). per minute).

While the Gisseller platometer method measures the rotational speed of the stirring rod at a constant torque, a method of measuring the torque by a constant rotation method is also devised. For example, Patent Document 1 discloses a method of measuring a torque while rotating the rotor at a constant rotation speed.

Moreover, there exists a measuring method of the viscosity by the dynamic viscoelasticity measuring apparatus for the purpose of measuring the viscosity which is physically meaningful as a softening melting characteristic (for example, refer patent document 2.). The dynamic viscoelasticity measurement is a measure of the viscoelastic behavior seen when a periodic force is applied to a viscoelastic body. In the method of patent document 2, the viscosity of softening molten coal is evaluated by the complex viscosity rate in the parameter obtained by a measurement, and it is a characteristic that the viscosity of the softening molten coal in arbitrary shear rates can be measured.

Moreover, the example which measured the coal softening melt adhesiveness to them using activated carbon or glass beads as a softening melting characteristic of coal is reported. It is a method of heating a small amount of coal samples in the state fitted with activated carbon and glass beads from the up-down direction, performing cooling after softening melting, and observing the adhesiveness of coal, activated carbon, and glass beads from an external appearance.

As a general method of measuring the expandability at the time of softening melting of coal, the dilatometer method prescribed | regulated to JIS M 8801 is mentioned. The dilatometry method measures coal crushed to 250 µm or less by a prescribed method, puts it into a predetermined crucible, heats it at a prescribed temperature raising rate, and measures the change of coal displacement over time with a detection rod placed on top of the coal. That's how.

A coal expansion test method is also known in which the permeation behavior of gas generated during coal softening and melting is improved to simulate coal softening and melting behavior in a coke oven (see, for example, Patent Document 3). This allows the measurement environment to be closer to the expansion behavior in the coke oven by placing a permeable material between the coal bed and the piston, or between the coal bed and the piston and the lower part of the coal bed, and increasing the permeation path of volatiles and liquid substances generated from coal. That's how. Similarly, the method of arrange | positioning the material which has a penetrating path | pass on the coal bed, and heating a coal by microwave heating while adding a load is also known (the patent document 4).

Japanese Patent Laid-Open No. Hei 6-347392 Japanese Patent Laid-Open No. 2000-304674 Japanese Patent Publication No. 2855728 Japanese Patent Publication No. 2009-204609

Morotomi et al .: Fuel Association Magazine, Vol. 53, 1974, p. 779-790 Miyazu et al .: Japan Steel Pipe Technology Report, vol.67, 1975, p.125-137

In the manufacture of metallurgical coke, it is common to use coal briquettes in which a plurality of brands of coal are blended at a predetermined ratio. However, if the softening and melting characteristics cannot be properly evaluated, the problem that the coke strength required is not satisfied. have. In the case of using a low-strength coke in a vertical furnace such as a blast furnace that does not satisfy a certain strength, the amount of powder generated in the vertical furnace increases, resulting in an increase in pressure loss and destabilizing operation of the vertical furnace. In addition, there is a possibility of causing a so-called channeling problem in which gas flow is locally concentrated.

Conventional softening melting characteristic indicators are often not able to accurately predict the strength. Therefore, empirically, in consideration of the variation in the coke strength resulting from the inaccuracy of the evaluation of the softening melting characteristics, managing the coke strength to a predetermined value or more by setting the target coke strength a little higher in advance is performed. In this method, however, it is necessary to set the average quality of the coal blend slightly higher using relatively expensive coal, which is generally known to have excellent softening and melting characteristics, resulting in an increase in cost.

In the coke oven, coal at the time of soft melting is soft melted in a state confined to an adjacent layer. Since the thermal conductivity of coal is small, coal does not heat similarly in a coke oven, and a state differs from a coke layer, a softening molten layer, and a coal layer from the furnace wall side which is a heating surface. The coke oven itself expands somewhat during dry distillation but hardly deforms, so the softened molten coal is confined to the adjacent coke layer and coal bed.

In addition, many defect structures are formed around coal softened and molten coal, such as interstitial voids in coal layers, interstitial voids in softened molten coal, coarse pores generated by volatilization of pyrolysis gas, and cracks in adjacent coke layers. Is present. In particular, the cracks formed in the coke layer are considered to have a width of several hundred microns to several millimeters, and are larger than pores and pores between coal particles having a size of several tens to hundreds of microns. Therefore, the coarse defect which arises in such a coke layer thinks that not only the pyrolysis gas and liquid substance which generate | occur | produce from coal, but also the penetration of the softened molten coal itself generate | occur | produce. In addition, the shear rate acting on the softened molten coal at the time of its penetration is expected to be different for each brand.

The inventors thought that in order to more precisely control the strength of the coke, it is necessary to use the coal softening melting characteristics measured under conditions simulating the environment in which the coal is placed in the coke oven as an index. Especially, it was thought that it was important to measure on the conditions which the softened molten coal was confined, and the conditions which simulated the movement and penetration of the melt to the surrounding defect structure. However, the conventional measuring method had the following problems.

Since the Giesler platometer method is a measurement in a state in which coal is filled in a container, it is a problem in that the restraint and penetration conditions are not considered at all. In addition, this method is not suitable for the measurement of coal showing high fluidity. The reason for this is that when measuring coal showing high fluidity, a phenomenon in which the inner wall of the container becomes hollow (Weissenberg effect) occurs, the stirring rod revolves, and fluidity may not be evaluated correctly (for example, For example, see Non-patent Document 1.).

Similarly, the method of measuring the torque by a constant rotation method has a disadvantage in that the restraint condition and the penetration condition are not considered. Moreover, since it is a measurement under a constant shear rate, as mentioned above, the softening melting characteristic of coal cannot be compared and evaluated correctly.

A dynamic viscoelasticity measuring device is an apparatus which targets viscosity as a soft melting characteristic, and can measure a viscosity under arbitrary shear rates. Therefore, if the shear rate at the time of measurement is set to the value acting on the coal in a coke oven, the viscosity of the softened molten coal in a coke oven can be measured. However, it is usually difficult to measure or estimate the shear rate in advance in the coke oven of each brand.

As softening melting characteristics of coal, the method of measuring the adhesion to them using activated carbon or glass beads is intended to reproduce the infiltration conditions for the presence of the coal layer, but does not simulate the coke layer and coarse defects. There is a problem. It is also insufficient in terms of measurement under restraint.

In the coal expansiveness test method using the permeable material described in Patent Literature 3, although the movement of gas and liquid substance generated from coal is considered, it is a problem in that the movement of softened and molten coal itself is not considered. This is because the permeability of the permeable material used in Patent Document 3 is not large enough so that the softened molten coal moves. When the present inventors actually performed the test of patent document 3, penetration of the softening molten coal into the permeable material did not occur. Therefore, it is necessary to consider new conditions in order to cause penetration of the softened molten coal into the permeable material.

Similarly, Patent Document 4 discloses a method for measuring the expandability of coal in which a material having a through path is disposed on a coal bed and considering the movement of gas generated from coal and liquid substances. However, in addition to the problem that the heating method is limited, coke There is a problem that the conditions for evaluating the penetration phenomenon in the furnace are not clear. In addition, in Patent Document 4, the relationship between the infiltration phenomenon of coal melt and softening melt behavior is not clear, and there is no suggestion on the relationship between the infiltration phenomenon of coal melt and the quality of coke to be produced. It is not described about.

As described above, in the prior art, fluidity, viscosity, adhesiveness, permeability, expansion rate of penetration, pressure at penetration, etc. of coal and binder are sufficiently simulated in the coke oven in a state that sufficiently simulates the environment of soft coal melted and binder. The softening and melting characteristics of the can not be measured.

Therefore, the present invention accurately evaluates the softening and melting characteristics of coal used in coal blended carbon by measuring the softening and melting characteristics of coal in a state of simulating the surrounding environment of softened and molten coal in a coke oven. After clarifying the influence on the coke strength, a method for producing a metallurgical coke having high quality such as strength by using the modified coal is reformed to have desirable softening melting characteristics by reforming the coal which adversely affects the coke strength. It aims to provide.

The characteristics of the present invention for solving such a problem are as follows.

[1] A method for producing coke by distilling a coal blend composed of two or more coals or a coal blend formed by blending a caking additive with two or more coals,

Filling the container with a sample of each coal and caking additive constituting the blended coal, and placing a material having a through hole on the upper and lower surfaces on the sample, and heating the sample, the sample of the sample penetrated into the through hole Measure the permeation distance and the highest flowability (logMF) by the Gisseller platometer method,

Selecting the coal whose penetration distance and the highest flow rate fall within a predetermined management range (A),

A part or all of the selected coal is weathered by normal temperature or heat treatment in an oxidizing atmosphere, so that the penetration distance and maximum flow rate of the coal after weathering are within a predetermined management range (B), and the weathered coal is A method for producing a metallurgical coke, characterized by blending.

[2] The method for producing metallurgical coke according to [1], wherein the management range (A) of the penetration distance and maximum flow rate satisfies the following formula (1) and formula (2).

logMF≥2.5 (1)

Penetration distance≥1.3 × a × logMF (2)

(However, "a" measures at least one or more penetration distances and logMF of coal and caking additives in the range of logMF <2.5 among the coals and caking additives constituting the coal blend, and uses the measured value as the origin It is an integer ranging from 0.7 to 1.0 times the coefficient of logMF when a regression line passing through is created.)

[3] The method for producing metallurgical coke according to [1], wherein the management range (A) of the penetration distance and maximum flow rate satisfies the following formula (3) and formula (4).

logMF≥2.5 (3)

Penetration distance≥a´ × logMF + b (4)

(However, “a” ”measures at least one or more penetration distances and logMF of coal and binder in the range of logMF <2.5 among the coals and binders constituting the coal blend, and uses the measured values) It is an integer in the range of 0.7 to 1.0 times the coefficient of logMF when a regression line passing through the origin is created, “b” indicates that one or more kinds of the same sample selected from the trademark used for the creation of the regression line are measured multiple times. It is an integer equal to or greater than the average value of the standard deviation at the time and 5 times or less the average value.)

[4] The management range (A) is

The blending ratio of coal or caking additive and coal or caking additive included in the coal blend used for producing coke is determined in advance,

Measure the penetration distance and logMF of the coal or caking additive,

What is determined by determining a range of twice or more as the management range (A) of the penetration distance with respect to the weighted average penetration distance calculated from the penetration distance of the coal or caking additive having a logMF of less than 3.2 and the compounding rate The manufacturing method of the metallurgical coke as described in [1] characterized by the above-mentioned.

[5] The control range (A) of the penetration distance is such that the coal or caking additive sample is pulverized so that the particle diameter is 2 mm or less to 100 mass%, and the pulverized sample is packed to have a packing density of 0.8 g / cm 3 and a layer thickness of 10 mm. Filled in a container to obtain a sample, the glass beads having a diameter of 2 mm were placed on the sample at a layer thickness of more than the penetration distance, and at a temperature rising rate of 3 ° C./min while applying a load such that the pressure was 50 kPa from the top of the glass beads. The method for producing metallurgical coke according to [1], wherein the measured value when heated in a inert gas atmosphere from room temperature to 550 ° C. is 15 mm or more and logMF is 2.5 or more.

[6] The weathering is the metallurgical coke according to any one of [1] to [5], which is weathered so that the penetration distance and maximum flow rate of the coal after weathering are within the management range (B) defined by the following formula (5). Manufacturing method.

Penetration distance <1.3 × a × logMF (5)

(However, "a" measures at least one or more penetration distances and logMF of coal and caking additives in the range of logMF <2.5 among the coals and caking additives constituting the coal blend, and uses the measured value as the origin It is an integer ranging from 0.7 to 1.0 times the coefficient of logMF when a regression line passing through is created.)

[7] The weathering is the metallurgical coke according to any one of [1] to [5], which is weathered so that the penetration distance and maximum flow rate of the coal after weathering are within the management range (B) defined by the following formula (6). Manufacturing method.

Penetration distance <a´ × logMF + b (6)

(However, “a” ”measures at least one or more penetration distances and logMF of coal and binder in the range of logMF <2.5 among the coals and binders constituting the coal blend, and uses the measured values) It is an integer in the range of 0.7 to 1.0 times the coefficient of logMF when a regression line passing through the origin is created, “b” indicates that one or more kinds of the same sample selected from the trademark used for the creation of the regression line are measured multiple times. It is an integer equal to or greater than the average value of the standard deviation at the time and 5 times or less the average value.)

[8] Measured at least one penetration distance and logMF of the coal and the caking additive in the range of 1.75 <logMF <2.50 among the coals and the caking additive of which “a” constitutes the coal blend, and the measured value is measured. It is an integer of the range of 0.7-1.0 times the coefficient of logMF when the regression line which passes through an origin is created using the manufacturing method of the metallurgical coke of [2] or [6] characterized by the above-mentioned.

[9] Among the coals and caking additives in which "a '" constitutes a coal mixture, at least one or more penetration distances and logMF of coals and caking additives in the range of 1.75 <logMF <2.50 are measured, and the measured value The manufacturing method of the metallurgical coke of [3] or [7] characterized by the above-mentioned.

[10] A blending ratio of the coal or caking additive of the coal or caking additive contained in the coal blend used for the coke production is determined in advance;

Measuring the penetration distance and logMF of the coal or caking additive of each said brand, and calculating the weighted average penetration distance calculated from the penetration distance of the coal or caking additive of each brand whose logMF contained in a coal blend is less than 3.2, and a compounding rate,

The method for producing metallurgical coke according to any one of [1] to [5], wherein the coal is weathered so that the penetration distance after the weathering falls within a management range (B) less than twice the weighted average penetration distance.

[11] The coal infiltrating distance after the weathering is pulverized the coal sample so as to have a particle size of 2 mm or less at 100 mass%. The glass beads having a diameter of 2 mm are placed on the sample at a layer thickness of more than the penetration distance, and a load is applied so as to have a pressure of 50 kPa from the top of the glass beads, while the temperature is raised from room temperature to 550 ° C. at a heating rate of 3 ° C./min. The manufacturing method of metallurgical coke in any one of [1]-[5] characterized by weathering so that it may become in the management range (B) which is less than 15 mm by the measured value at the time of heating in inert gas atmosphere.

[12] The method for producing metallurgical coke according to any one of [6] to [11], in which the maximum flow rate of the coal after weathering is logMF ≧ 2.5 and is within a management range (B).

[13] The metallurgical use according to any one of [1] to [12], wherein the oxidizing atmosphere at the time of performing the weathering is a gas atmosphere containing at least one component of O ₂ , CO ₂ , and H ₂ O. Method of making coke.

[14] The method for producing metallurgical coke according to [13], wherein the oxidizing atmosphere at the time of performing the weathering is an air atmosphere.

[15] The method for producing metallurgical coke according to any one of [1] to [14], wherein the heat treatment at the time of performing the weathering is a treatment temperature of 100 ° C to 300 ° C and a treatment time of 1 to 120 minutes.

[16] The method for producing metallurgical coke according to [15], wherein the heat treatment when the weathering is performed is a treatment temperature of 180 ° C to 220 ° C and a treatment time of 1 to 30 minutes.

[17] [1] to [16] characterized in that, when the weathering is carried out, part or all of the coal and caking additive used for coke production are classified in advance, and only particles having a predetermined sieve mesh or more are weathered. The manufacturing method of the metallurgical coke in any one of them.

[18] The metallurgical coke according to [17], wherein the predetermined body is selected from the range of 1 mm to 6 mm when classifying the coal and the caking additive used in the coke production during the weathering. Method of preparation.

[19] The measurement according to any one of [1] to [18], wherein the measurement of the penetration distance heats the sample at a predetermined heating rate while applying a constant load from a material having a through hole on the upper and lower surfaces. The manufacturing method of the metallurgical coke of description.

[20] The measurement according to any one of [1] to [18], wherein the measurement of the penetration distance heats the sample at a predetermined heating rate while maintaining the sample and a material having through holes in the upper and lower surfaces in a predetermined volume. The manufacturing method of the metallurgical coke of one.

According to the present invention, it is present in the defect structure present around the coal softening melt layer in the coke oven, especially the coke layer adjacent to the soft melt layer, which is considered to have a great influence on the coal softening melting characteristics in the coke oven. The influence of cracks to be simulated and the softening melting characteristics of the coal to the caking additive can be evaluated in a state in which the constraint conditions around the softening melt in the coke oven are properly reproduced. This makes it possible, in particular, to predict the generation of defects derived from coal or caking additives that exhibit excess fluidity that could not be detected in the conventional softening melting characteristics evaluation method, and identify coal or caking additives that adversely affect the coke quality. can do. And since the coal which has undesirable softening melting characteristic can be reformed so that it may have a preferable softening melting characteristic in coke manufacture by a weathering process, it has the effect that the fall of coke strength suppression and the improvement of coke strength are implement | achieved.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows an example of the apparatus which measures the softening melting characteristic, adding a fixed load to the material which has a through-hole on the upper and lower surfaces with the coal and caking additive sample used by this invention.
Fig. 2 is a schematic diagram showing an example of a material having a circular through hole among the materials having a through hole in the upper and lower surfaces used in the present invention.
Fig. 3 is a schematic diagram showing an example of a spherical particle filling layer among materials having through holes on the upper and lower surfaces used in the present invention.
Fig. 4 is a schematic diagram showing an example of a circumferential filling layer among materials having through holes on the upper and lower surfaces used in the present invention.
[Fig. 5] In the conventional formulation defined in the present invention, the strength is lowered, but the range of penetration and maximum flow rate in which coal and caking additives exist that can suppress the strength decrease by performing weathering (a) ), The range of penetration and maximum flow of suitable weathering coal (corresponding to (e)), and the range of range of penetration and maximum flow of most suitable weathering coal (corresponding to It is a schematic diagram to show.
FIG. 6: In general mixing as defined in the present invention, the strength decreases, but the range of penetration and maximum flow rate in which coal and caking additives exist that can suppress the strength decrease by performing weathering ((b)) This is a schematic diagram showing the penetration distance of the weathering coal and the range of the highest flow rate (corresponding to (bar), and the range of the penetration distance and the highest flow rate of the most suitable weathering coal.
Fig. 7 The range of permeation distance and maximum flow rate in which coal and caking additives exist that can cause a decrease in strength in the conventional formulation defined in the present invention, but can suppress the decrease in strength by performing weathering ((C)). This figure is a schematic diagram showing the range of the penetration distance and the highest flow rate of a suitable weathering coal (corresponding to (g)), and the range of the penetration distance and the maximum flow rate of the most suitable weathering coal (corresponding to (i)).
FIG. 8 The range of penetration distance and maximum flow rate in which coal and caking additives exist that can cause a decrease in strength in the conventional formulation defined in the present invention, but can suppress the decrease in strength by performing weathering. This is a schematic diagram showing the range of the penetration distance and the highest flow rate of the suitable weathering coal (corresponding to (h)), and the range of the penetration distance and the highest flow rate of the most suitable weathering coal (corresponding to (child)).
9 is a graph showing a measurement result of a penetration distance of a coal softening melt measured in the present invention.
FIG. 10 is a graph showing the positional relationship between the penetration distance and maximum flow rate of coal and F-coal constituting the coal briquettes prepared in Example 1, and the range of penetration distance and maximum flow rate corresponding to (a). FIG.
11 is a graph showing the positional relationship between the penetration distance and maximum flow rate of coal and F-coal constituting the coal briquettes prepared in Example 1, and the range of penetration distance and maximum flow rate corresponding to (b).
12 is a result of measuring the drum strength of coke measured in Example 1. FIG.
FIG. 13 shows the positional relationship between the penetration distance and the highest flow rate of the weathered F bomb produced in Example 1, and the range (the range below the line in the formula (1)) of the penetration distance and the maximum flow rate corresponding to (e). It is a graph.
FIG. 14 shows the positional relationship between the penetration distance and the highest flow rate of the weathered F-coal produced in Example 1, and the range of the penetration distance and the maximum flow rate (bar) below the line in Equation (2) corresponding to (bar). It is a graph.
15 is a range of penetration distance and maximum flow rate of weathered F coal produced in Example 1, and a range of penetration distance and maximum flow rate corresponding to (G) (weighted average of base mixed coals having logMF of less than 3.2 coal); It is a graph which shows the positional relationship of the range below the straight line of penetration distance 13 mm which is twice the penetration distance 6.5 mm.
FIG. 16: Positional relationship between the penetration distance and the highest flow rate of the weathered F bomb produced in Example 1, and the range (the range below the straight line having an penetration distance of 15 mm) corresponding to (A). A graph representing.
FIG. 17 is a graph showing changes in penetration distance and maximum flow rate of weathered F-coal produced by changing the treatment temperature.
18 is a graph showing the positional relationship between the penetration distance and the maximum flow rate of U-carbons used in Example 2, the penetration distance corresponding to (A), and the range of the maximum flow rate.
FIG. 19 is a graph showing the positional relationship between the penetration distance and maximum flow rate of U-coal used in Example 2 and the range of penetration distance and maximum flow rate corresponding to (b). FIG.
Fig. 20 is a schematic diagram showing an example of an apparatus for measuring softening melting characteristics while maintaining a constant volume of a material having a through hole in the upper and lower surfaces of a coal sample used in the present invention.

MEANS TO SOLVE THE PROBLEM The present inventors made it possible to measure softening melting characteristics in the state which simulated the surrounding environment of the softening molten coal in a coke oven, and repeated earnest research about the relationship between the "penetration distance" which is the measured softening melting characteristic, and coke strength. Thus, the following findings were obtained.

• Even if coal has almost no difference in softening melting characteristics reported in the past, there is a difference in softening melting characteristics by the method of the present invention measured in the state of simulating the environment of softened and molten coal.

• When coke is manufactured by mixing coal having a difference in softening melting characteristics measured by the method of the present invention, their coke strength is also different.

Based on the above findings, the inventors of the present invention have found a method of modifying coal, which adversely affects coke strength, to have desirable softening melting characteristics, and have thus arrived at the present invention.

An example of the measuring apparatus of the softening melting characteristic (penetration distance) used by this invention is shown in FIG. 1 is an apparatus in the case of heating a coal sample by applying a constant load to a material having a through hole in the upper and lower surfaces of the coal sample. Coal is filled in the lower part of the container 3, and it is set as the sample 1, and the material 2 which has a through-hole in the upper and lower surfaces is arrange | positioned on the sample 1. The sample 1 is heated to the softening melting start temperature or more, the sample is made to penetrate into the material 2 which has a through hole in the upper and lower surfaces, and a penetration distance is measured. Heating is performed in an inert gas atmosphere. Here, an inert gas refers to the gas which does not react with coal in a measurement temperature range, and typical gas is argon gas, helium gas, nitrogen gas, etc. In addition, the measurement of the penetration distance may be performed while heating the material having the coal and the through hole at a constant volume. An example of the measuring apparatus of the softening melting characteristic (penetration distance) used in that case is shown in FIG.

When a certain load is applied to the material 2 having the through holes on the upper and lower surfaces of the sample 1 shown in FIG. 1 and the sample 1 is heated, the sample 1 exhibits expansion or contraction, and the through holes are formed on the upper and lower surfaces. The material 2 having it moves in the vertical direction. Therefore, it is possible to measure the expansion rate at the time of permeation of the sample through the material (2) having the through holes in the upper and lower surfaces. As shown in FIG. 1, the expansion rate detection rod 13 is arrange | positioned at the upper surface of the material 2 which has a through-hole on the upper and lower surfaces, the weight 14 for load application is mounted on the upper end of the expansion rate detection rod 13, The displacement meter 15 is placed thereon, and the expansion rate is measured. As the displacement meter 15, one capable of measuring the expansion range (-100% to 300%) of the expansion rate of the sample may be used. Since it is necessary to maintain the inside of a heating system in an inert gas atmosphere, a non-contact displacement meter is suitable and it is preferable to use an optical displacement meter. As an inert gas atmosphere, it is preferable to set it as nitrogen atmosphere. When the material 2 having a through hole in the upper and lower surfaces is a particle-filled layer, there is a possibility that the inflation rate detecting rod 13 is buried in the particle filling layer. Therefore, It is desirable to take a measure to sandwich the plate between the plate 13 and the plate. The load to be added is preferably equally applied to the upper surface of the material having the through hole on the upper and lower surfaces disposed on the upper surface of the sample, and is 5 to 80 kPa, preferably 15 to the area of the upper surface of the material having the through hole on the upper and lower surfaces. It is preferable to add a pressure of ˜55 kPa, most preferably 25 to 50 kPa. Although this pressure is preferably set based on the expansion pressure of the softened molten layer in the coke furnace, the expansion pressure in the furnace is considered as a result of examining the reproducibility of the measurement result and the detection power of the brand difference in various coals. Rather, it was found that a slightly higher degree of 25-50 mm was most preferable as the measurement condition.

It is preferable to use a heating means which can be heated at a predetermined heating rate while measuring the temperature of the sample. Specifically, it is an electric furnace, an external heating type in which a conductive container is combined with high frequency induction, or an internal heating type such as a microwave. In the case of adopting the internal heating type, it is necessary to devise a device to make the temperature in the sample uniform. For example, it is preferable to take measures to increase the thermal insulation of the container.

About the heating rate, it is necessary to match the heating rate of the coal in a coke oven from the objective of simulating the soft melting behavior of coal and caking additives in a coke oven. The heating rate of coal in the softening melting temperature range in the coke oven is generally 2 to 10 ° C./min, depending on the position and operating conditions in the furnace, and is preferably 2 to 4 ° C./min as the average heating rate. Most preferred is about 3 ° C / min. However, in the case of coal having low fluidity, such as non-coking coal, the penetration distance and expansion are small at 3 ° C / min, which may make detection difficult. It is generally known that coal is rapidly heated to improve fluidity by a gaseous plastometer. Therefore, for example, in the case of coal whose penetration distance is 1 mm or less, in order to improve detection sensitivity, you may measure by raising a heating rate to 10-1000 degreeC / min.

About the temperature range in which heating is performed, since the purpose of evaluation is the softening melting characteristic of coal and a caking additive, what is necessary is just to be able to heat to the softening melting temperature range of coal and a caking additive. Considering the softening and melting temperature range of coal and the point binder for coke production, it is preferable that the temperature is in the range of 0 占 폚 (room temperature) to 550 占 폚, preferably at the softening and melting temperature of coal of 300 to 550 占 폚 at a predetermined heating rate Heating is good.

It is preferable that the material having the through hole in the upper and lower surfaces is capable of measuring or calculating the transmission coefficient in advance. As an example of the form of the material, an integral type material having a through hole, a particle filled layer can be mentioned. As an integral type of material having a through hole, for example, one having a circular through hole 16 as shown in FIG. 2, one having a rectangular through hole, one having an irregular through hole, and the like can be mentioned. . As a particle filling layer, it is divided roughly into a spherical particle filling layer and a non-spherical particle filling layer, As a spherical particle filling layer what consists of the filler particles 17 of beads as shown in FIG. 3, As a non-spherical particle filling layer, And the filling cylinder 18 as shown in FIG. 4, etc. are mentioned. In order to maintain the reproducibility of the measurement, it is preferable that the transmission coefficient in the material is as uniform as possible and that the calculation of the transmission coefficient is easy in order to facilitate the measurement. Therefore, the use of the spherical particle filled layer is particularly preferable for the material having the through hole in the upper and lower surfaces used in the present invention. The material of the material having the through holes in the upper and lower surfaces is not particularly designated as long as the shape hardly changes to the coal softening melting temperature range, specifically, up to 600 ° C. and does not react with coal. In addition, the height may be a height sufficient for the melt of the coal to penetrate, and in the case of heating the coal layer having a thickness of 5 to 20 mm, it may be about 20 to 100 mm.

It is necessary to estimate and set the transmission coefficient of the coarse defect which exists in a coke layer as the transmission coefficient of the material which has a through hole on the upper and lower surfaces. As a result of the present inventors' examination, such as consideration of the coarse defect component factor and estimation of the magnitude | size about the permeability coefficient especially preferable for this invention, when the permeability coefficient is 1x10 <^{8> -2} * 10 <^9> m <^-2> , it is optimal. Found that This transmission coefficient is derived based on the Darcy law shown in the following formula (7).

ΔP / L = K · μ · u... (7)

Where ΔP is the pressure loss [Pa] in the material having the through holes at the top and bottom, L is the height [m] of the material having the through holes, K is the transmission coefficient [m ⁻² ], μ is the viscosity of the fluid [Pa S] and u are the velocity of the fluid [㎧]. For example, when using the glass beads layer of uniform particle diameter as a material which has a through-hole in the upper and lower surfaces, it is preferable to select glass beads about 0.2 mm-3.5 mm in diameter, in order to have a suitable transmittance | permeability mentioned above, Most preferred is 2 mm.

Coal and caking additive used as a measurement sample are previously grind | pulverized, and it fills with predetermined | prescribed layer thickness at predetermined | prescribed packing density. The pulverization particle size may be a particle size of the charged coal in the coke oven (the ratio of particles having a particle diameter of 3 mm or less is about 70 to 80 mass% of the whole), and pulverizing so that the particle size of 3 mm or less is 70 mass% or more. Although it is preferable, it is especially preferable to use the grind | pulverized object which grind | pulverized the whole quantity into 2 mm or less in consideration of the measurement in a small apparatus. The density of filling the pulverized product can be set to 0.7 to 0.9 g / cm 3 in accordance with the packing density in the coke oven. However, as a result of examining reproducibility and detection power, it was found that 0.8 g / cm 3 is preferable. Moreover, although the layer thickness to be filled can be 5-20 mm based on the thickness of the softening molten layer in a coke oven, as a result of examining reproducibility and a detection force, it turns out that it is preferable to set it as 10 mm. did.

In the measurement of the above penetration distance, typical measurement conditions are described below.

(1) Coal or caking additives are ground to a particle size of 2 mm or less to 100% by mass, and the pulverized coal or caking additives are packed into a container with a packing density of 0.8 g / cm 3 and a layer thickness of 10 mm to prepare a sample. Write,

(2) The glass beads of diameter 2mm are arrange | positioned on the sample so that it may become the layer thickness more than a penetration distance,

(3) heating under an inert gas atmosphere from room temperature to 550 ° C. at a heating rate of 3 ° C./min, adding a load such that it is 50 kPa from the top of the glass beads,

(4) The penetration distance of the molten sample which penetrated the said glass bead layer is measured.

It is inherently preferable that the penetration distance of the softened melt of the coal and the point binder is continuously and continuously measured during heating. However, the normal measurement is difficult due to the influence of tar on the sample. The expansion and infiltration of coal by heating is irreversible, and since its shape is maintained even after cooling once inflated and infiltrated, the entire container is cooled after the coal melt has finished infiltration, and the penetration distance after cooling is measured. By doing so, you may measure to what extent it penetrated during heating. For example, it is possible to take out the material which has a through hole in the upper and lower surfaces from the container after cooling, and to measure it directly with a caliper or a ruler. In the case where particles are used as the material having the through holes on the upper and lower surfaces, the softened melt penetrated into the interparticle pores fixes the entire particle layer up to the penetrated portion. Therefore, if the relationship between the mass and the height of the particle packing layer is obtained in advance, the mass of the particles to which the particles are stuck can be derived by measuring the mass of the particles that are not fixed after the infiltration and subtracting them from the initial mass. From there, the penetration distance can be calculated.

Such superiority of penetration distance is not only assumed in principle based on taking a measurement method close to the coke oven situation, but also evident from the result of examining the influence of the penetration distance on the coke strength. Indeed, according to the evaluation method of the present invention, even if coal having the same degree of logMF (commercial algebraic value of the highest flow rate by the gaseous plastometer method), it is evident that there is a difference in the penetration distance depending on the brand, and the penetration distance It was confirmed that the effect on the coke strength when the coke was prepared by mixing different coals was also different.

In the evaluation of the softening melting characteristic by the conventional gaseous plastometer, it has been thought that the coal which shows high fluidity has a high effect of adhering coal particles. On the other hand, by investigating the relationship between the penetration distance and the coke strength, coking with extremely large penetration distances leaves coarse defects when coking, and forms a thin porous wall structure. It turned out that strength falls compared with the value anticipated from the average quality of a coal blend. This is presumably because coal having too large a penetration distance penetrates remarkably between surrounding coal particles, and the portion in which the coal particles have existed becomes a large cavity and becomes a defect. Particularly, in the coal showing high fluidity in the evaluation of softening melting characteristics by the Gisseltler plastometer, it was found that the amount of coarse defects remaining in the coke varies depending on the magnitude of the penetration distance. This relationship was also shown with regard to caking additives.

As a result of intensive studies by the present inventors, it is effective to define the range of coal to caking additive that causes a decrease in coke strength when blended and used in a raw material for producing coke, in the following four types (a) to (d). Found that.

(A) Range prescribed | regulated by following formula (1) and formula (2).

logMF≥2.5 (1)

Penetration distance≥1.3 × a × logMF (2)

However, "a" measures at least one or more penetration distances and logMF of coal and caking additives in the range of logMF <2.5 among the coals and caking additives constituting the coal blend, and uses the measured values to determine the origin. It is an integer in the range of 0.7-1.0 times the coefficient of logMF when the regression line which passes through is created.

(B) The range prescribed by the following formula (3) and formula (4).

logMF≥2.5 (3)

Penetration distance≥a´ × logMF + b (4)

However, "a" measures at least one or more penetration distances and maximum flow rates of coal and binder in the range of logMF <2.5 among the coals and binders constituting the coal blend, and uses the measured values. This is an integer in the range of 0.7 to 1.0 times the coefficient of logMF when a regression line passing through the origin is created. "B" is an integer greater than or equal to the average value of the standard deviations when the one or more types of the same sample selected from the trademark used for the creation of the regression line are measured multiple times, and set to 5 times or less of the average value.

(C) If the brand and blending rate of the coal briquettes used for coke production can be determined in advance, the weighted average penetration distance calculated from the penetration distance of coal or caking additive of each brand having a logMF of less than 3.2 and the blending ratio are included. More than twice. At this time, the average penetration distance is preferably determined by a weighted average in consideration of the blending ratio, but can also be substituted by a simple average value.

(D) A coal sample prepared with a particle size of 2 mm or less and a particle size of 100 mass% was filled in a container with a thickness of 10 mm at a packing density of 0.8 g / cm 3, and using glass beads having a diameter of 2 mm as a material having a through hole, A penetration of 15 mm or more and a logMF of 2.5 or more, when a load of 50 kPa was applied and the temperature was measured by heating to 550 ° C. at a heating rate of 3 ° C./min.

Here, the method of determining the four types of management values (A) to (D) described above means that the value of the penetration distance is a set measurement condition, for example, a load, a temperature increase rate, a kind of material having a through hole, an apparatus. It is because it changes according to the configuration, etc., and the result of having considered that there may be measurement conditions different from the example described in this invention, and found that the method of determining the management value as (a)-(c) is effective It is based on.

In addition, the constants a and a 'in formulas (2) and (4) used in determining the ranges (a) and (b) are at least one or more penetration distances and maximum flow rates of coal in the range logMF <2.5. Is measured and determined to be within a range of 0.7 to 1.0 times the coefficient of logMF when a regression line passing through the origin is created using the measured value. This is because in the range of logMF <2.5, there is a roughly positive correlation between the maximum flow rate of coal and the penetration distance, but the trademark that causes the decrease in strength is a trademark in which the penetration distance is greatly inclined positively from this correlation. to be. As a result of intensive studies, the inventors have found that a trademark corresponding to a range of 1.3 times or more of the penetration distance determined by the logMF value of coal by the regression formula is a trademark that causes a decrease in strength. , (2) decided to implement the scope. Moreover, based on the understanding that the trademark which inclines positively beyond a measurement error is not preferable from the said regression formula, it is more than the value which added 1-5 times the standard deviation at the time of measuring the same sample multiple times to the said regression formula. It was found that the trademark corresponding to the range was a trademark causing the strength deterioration, and it was assumed that the regulation of the range was carried out by equations (3) and (4). Therefore, the integer b may use a value of 1 to 5 times the standard deviation when the same sample is measured multiple times, and in the case of the measurement conditions described in the present invention, it is about 0.6 to 3.0 mm. At this time, the formulas (2) and (4) both determine the range of the penetration distance that causes a decrease in strength based on the logMF value of the coal. This is because the larger the MF is, the larger the penetration distance generally becomes, which is why it is important to incline from the correlation. In addition, you may use the method of linear regression by the well-known least-squares method for preparation of a regression straight line. The larger the number of coals used in the regression, the smaller the error in the regression. In particular, in a brand with a small MF, the penetration distance is small and the error tends to be large. Therefore, it is particularly preferable to obtain a regression straight line using one or more kinds of coal in the range of 1.75 <logMF <2.50.

Here, the constants a, a ', and b both define ranges because by reducing these values, it is possible to more reliably detect coals that cause a decrease in strength, and the values can be adjusted according to operational requirements. have. However, if this value is made too small, there will be a problem that too many coals are estimated to adversely affect the coke strength, and that the coal will not cause a decrease in strength even if the coal does not actually cause a decrease in strength. , a and a 'are preferably 0.7 to 1.0 times the inclination of the regression line, and b is preferably 1 to 5 times the standard deviation when the same sample is measured multiple times.

Coal to caking additives used in blended coal are usually measured and used in various grades in advance for each brand. Similarly, the penetration distance may be measured for each lot of the trademark in advance. The average penetration distance of the coal blended coal may be measured in advance by each brand, and the value may be averaged according to the blending ratio, or a coal blended coal may be prepared to measure the penetration distance. This makes it possible to select a brand having a very large penetration distance with respect to the average penetration distance of the coal briquettes. The coal blend used for coke production may contain oil, powder coke, petroleum coke, resins, waste, etc. in addition to coal or a caking additive.

Coal and caking additives according to the above (A) to (D), when used under ordinary pretreatment conditions as raw coal of coke, leave coarse defects when coking, and form a structure of thin pore walls. It causes a decrease in coke strength. Therefore, it is simple and effective as means for maintaining coke strength to take measures to limit the compounding ratio of the trademark and point binder. However, from the viewpoint of stable procurement of raw materials, in the current coke production aiming at blending a large number of producers and many brands, even if coal or caking additives corresponding to (a) to (d) can be used for them, There is a lot.

MEANS TO SOLVE THE PROBLEM Even when using the coal blend which mixes the coal and caking material of said (a)-(d) as a coke raw material, the present inventors naturally apply the coal and caking material of (a)-(d) beforehand. It has been found that the reduction in strength can be suppressed by forcibly weathering by heating or by controlling the values of penetration distance and maximum flow rate. When coal comes into contact with air after mining, the properties gradually change due to gradual deterioration or decrease in gloss. Moreover, coking property (maximum fluidity | liquidity etc.), a calorific value, and coking conversion property also fall, and the quality as a coke raw coal is inferior. This phenomenon is called weathering. If the coal is weathered, the penetration distance decreases with the progress of the weathering. As a result of intensive research by the present inventors, when the coal corresponding to (a) to (d) is forcibly weathered in advance by natural or heat treatment, the penetration distance and the highest flow rate of coal after weathering are It was discovered that the coke strength can be effectively suppressed by controlling the method or the progress of the weathering so as to fall within the range of ()).

(E) Weathering is carried out so that the penetration distance and maximum flow rate of the weathering coal are within the range specified by the following formula (5).

Penetration distance <1.3 × a × logMF (5)

(F) Weathering is carried out so that the penetration distance and maximum flow rate of the weathering coal are within the range specified by the following formula (6).

Penetration distance <a´ × logMF + b (6)

Here, a, a ', and b can be obtained in the same manner as in the case of the determination of the ranges (a) and (b) above.

(G) If the brand and compounding rate of the coal briquettes used for coke production can be determined in advance, the weighted average penetration distance calculated from the penetration distance of coal or caking additive of each brand having a logMF of less than 3.2 and the blending ratio are included. It is weathered to less than 2 times.

(H) A sample having a penetration distance of weathered coal having a diameter of 2 mm or less and a particle size of 100 mass% was filled in a container with a thickness of 10 mm at a packing density of 0.8 g / cm 3 and a glass having a diameter of 2 mm as a material having a through hole. Using a bead, a load of 50 kPa was applied and weathered so as to be less than 15 mm at a penetration distance in the case of measuring by heating to 550 ° C. at a heating rate of 3 ° C./min.

(I) The weathering coal is weathered so that the penetration distance satisfies at least one of (e) to (h), and the maximum flow rate is in the range of logMF? 2.5.

As a result of intensive studies by the present inventors, it has been found that, as a property of weathered coal, a small penetration distance and a high maximum fluidity are preferable in improving coke strength at the time of blending. As the reason, the lower penetration distance is preferred as described above, but the higher fluidity is preferred because adhesion between the particles is performed well when the coal softens and melts. Therefore, it is preferable to control the method or the progress of the weathering so that the penetration distance of the weathering coal satisfies at least one of (e) to (h), and the maximum fluidity is not reduced as much as possible in producing high strength coke. Do. Therefore, as described in (i), by setting the maximum flow rate of the weathered coal to the range of logMF? 2.5, it is possible to effectively suppress the decrease in strength without causing adhesion failure.

In the usual formulations corresponding to the above (a) to (d), the strength is lowered, but the range of penetration and maximum flow rate in which coal and caking additives exist that can suppress the strength decrease by performing weathering, Putting together the range of the suitable weathering coal penetration distance and the highest flow rate corresponding to (e)-(h), and the range of the most suitable weathering coal penetration distance and the maximum flow rate corresponding to (i), It shows typically in 5-8. In addition, (za) is contained in the range of (e)-(h).

It is generally known that the rate of progress of weathering of coal depends on oxygen concentration, atmospheric pressure, temperature, coal particle diameter, coal moisture, and the like. When weathering coal in order to control the value of the penetration distance and the maximum flow rate, it is good to control the said weathering factor suitably.

The present inventors found that the permeation distance and the drop rate of the highest flow rate differed depending on the weathering conditions by performing the experiment of weathering coal by changing the above weathering factors. As a result of repeated examinations in which various weathering conditions were changed, a suitable weathering method was found in producing a weathering coal having a property corresponding to (i). Hereinafter, the specific method is described.

The atmosphere at the time of performing weathering needs to be an oxidizing atmosphere. The oxidizing atmosphere here is an atmosphere containing oxygen, or a substance containing a substance having the ability to dissociate and oxidize oxygen. Although such conditions exist innumerably, considering the ease of obtaining and controlling, a gas atmosphere containing O ₂ , CO ₂ , H ₂ O is preferable. In the gas atmosphere, the oxidizing power can be easily adjusted by the concentration and pressure of the oxidizing gas, and by substituting the inert gas after the treatment, the progress of oxidation of the coal and the caking additive can be restrained quickly, so that the processing time can be arbitrarily selected. Can be set. Here, the higher the concentration of the oxidizing gas, the higher the pressure, the faster the progress of weathering. On the other hand, in the case of an oxidizing liquid atmosphere, it is difficult to quickly separate from coal and caking additives after the weathering treatment, which is not preferable in controlling the progress of the weathering.

In addition, the cheapest, easiest and largely available oxidizing atmosphere is air in the atmosphere. Therefore, when industrial mass processing is required, it is preferable to use air in the atmosphere as an oxidizing atmosphere.

As the treatment temperature at the time of performing the weathering, any one of the range from the normal temperature at which the weathering phenomenon of coal occurs to the temperature immediately before the coal shows softening melting can be performed. The progress of the weathering is faster as the temperature increases, so the processing time required for producing the weathering coal having properties corresponding to (e) to (i) becomes shorter as the processing temperature is higher. As a result of investigating the effect of the treatment temperature on the weathering coal properties, the inventors found that the higher the treatment temperature, the faster the rate of reduction of the penetration distance with respect to the rate of decrease of the highest flow rate of the weathered coal. That is, it is possible to preferentially lower the penetration distance without lowering the maximum flow rate of the weathered coal as much as the weathering at high temperature. Therefore, the inventors discovered that high temperature and short time were effective as conditions for the treatment temperature and treatment time suitable for producing weathered coal having properties corresponding to (i).

On the other hand, if the coal is weathered rapidly, there is a risk of spontaneous ignition accompanying oxidative heating, and therefore, measures to prevent spontaneous ignition, such as watering, need to be taken. In addition, when the processing temperature is too high, the speed of weathering is high, and thus it is difficult to control the properties after the weathering treatment. In addition, since coal starts to release volatile matter by pyrolysis from a portion exceeding 300 ° C, the softening melting characteristics change. In addition, weathering treatment in the temperature range where volatile matter is released causes flammable gas to be present under heating conditions in an oxidizing atmosphere, and involves the risk of explosion.

For the reason mentioned above, as processing temperature at the time of performing weathering, 100 to 300 degreeC and 1 to 120 minutes are preferable as processing time. Most preferably, as processing temperature at the time of performing weathering, 180 to 220 degreeC and 1 to 30 minutes are preferable as processing time.

As a particle diameter of a coal at the time of carrying out a weathering process, it is preferable to classify part or all of the coal and caking additive corresponding to (A)-(D) beforehand, and to weather only the particle | grains more than a predetermined | prescribed trunk. This reason can be explained as follows.

The reason why the coal and the caking additive corresponding to (A) to (D) lowers the coke strength at the time of blending is to leave coarse defects when coking, and to form a thin pore wall structure. The present inventors have found that even coals and caking additives corresponding to (a) to (d) do not cause coarse defects in the case of fine particles, and thus do not cause a decrease in coke strength.

In addition, since fine granules have a large specific surface area at the time of weathering treatment, weathering advances preferentially compared with granulation. Therefore, in the case of weathering all the particles of coal and the caking additive corresponding to (A) to (D), coarse particles that cause a decrease in strength are appropriately applied as corresponding to (E) to (R). On the contrary, when the weathering is performed, the fine particles are too weathered so that the maximum fluidity is out of the range of logMF? 2.5, resulting in poor adhesion, resulting in a decrease in coke strength.

Therefore, the fall of strength can be suppressed effectively by only taking out the granulation part of the coal and caking additives which correspond to (A)-(D) which bring about the fall of coke strength in advance by weathering. As a body, 1 mm is preferable because it can be divided into granules which bring about a fall of strength, and the granule which is easy to advance. In addition, although the classification is generally performed by a screening process, it may be classified by other methods, and fine grains inevitably contained in the granulated portion may be present.

The inventors of the present invention can select the coal causing the coke strength drop as described above, weather them under appropriate weathering conditions, and modify the coal to weathered coal having appropriate coking property, and then mix it, thereby suppressing the coke strength drop. It has been found and the present invention has been completed.

[Example]

Example 1

The penetration distance was measured about 21 types of coal (coal A-U) and 1 type of caking additives (caking additive V). The property values of used coal and caking additive are shown in Table 1. Here, Ro is the Vitrinite average maximum reflectance of coal according to JIS M 8816, logMF is the common logarithm value of the maximum fluidity (MF) measured by Giesler platometer method, volatile matter (VM), ash (Ash) Is a measured value by the industrial analysis method of JIS M 8812.

The penetration distance was measured using the apparatus shown in FIG. Since the heating method was a high frequency induction heating type, the heat generating body 8 of FIG. 1 was an induction heating coil, and the raw material of the container 3 used graphite which is a dielectric material. The diameter of the container was 18 mm and height 37 mm, and glass beads having a diameter of 2 mm were used as a material having through holes in the upper and lower surfaces. The sample 1 is pulverized to a particle size of 2 mm or less and 2.04 g of a vacuum sample vacuum dried at room temperature is charged into the container 3, and a weight of 200 g is dropped from the coal sample on a falling distance of 20 mm five times. It filled (in this state, the sample layer thickness became 10 mm). Next, the glass beads of diameter 2mm were arrange | positioned so that it might become thickness of 25 mm on the filling layer of the sample 1. A disk of 17 mm diameter and 5 mm thick silica wire was placed on the glass bead filling layer, and a quartz rod was placed thereon as the expansion coefficient detecting rod 13, and 1.3 kg of weight 14 was placed on the quartz rod. Put it. As a result, the pressure applied to the whetstone disk is 50 kPa. Nitrogen gas was used as an inert gas, and it heated to 550 degreeC at the heating rate of 3 degree-C / min. After the end of heating, cooling was performed in a nitrogen atmosphere, and the beads mass not fixed to coal softened and melted were measured from the container after cooling. In addition, although the said measurement conditions were decided by the inventors as the measurement conditions of a preferable penetration distance by the comparison of the measurement result in various conditions, penetration distance measurement is not limited to this method.

In addition, what is necessary is just to arrange | position so that the thickness of a glass bead layer may become a layer thickness more than a penetration distance. In the case where the melt has penetrated to the top of the glass bead layer at the time of measurement, the glass beads are increased and remeasurement is performed. The inventors carried out a test in which the layer thickness of the glass beads was changed, and when the glass bead layer thickness is larger than the penetration distance, it is confirmed that the penetration distance measurement values of the same sample are the same. When carrying out the measurement of the caking additive having a large penetration distance, a larger container was used, and the filling amount of the glass beads was also increased to carry out the measurement.

The penetration distance was made into the filling height of the bead layer which stuck. The relationship between the filling height and the mass of the glass beads packed layer was calculated in advance, and the glass beads filling height was derived from the mass of the beads to which softened and molten coal was fixed. The result was equation (8), and the penetration distance was derived from equation (8).

L = (G-M) × H... (8)

Where L is the penetration distance [mm], G is the glass bead mass [g] filled, M is the bead mass [g] which is not fixed to the softening melt, and H is the filling per 1 g of glass beads filled in the present experimental apparatus. Layer height [mm / g] is shown.

The relationship between the penetration distance measurement result and the logarithmic value (logMF) of the Gissel maximum fluidity (MF) is shown in FIG. 9. In Fig. 9, the penetration distance measured in this embodiment is correlated with the highest flow rate, but the same MF has a difference in the value of the penetration distance. For example, considering the measurement error of the penetration distance in the apparatus, considering that the standard deviation was 0.6 for the result of three tests under the same conditions, coal A and coal C having approximately the same maximum flow rates For, a significant difference in penetration distance was recognized.

Next, in order to investigate the change in the penetration distance, the maximum flow rate, and the coke strength after dry distillation due to the weathering of coal corresponding to (a) to (d), the coals corresponding to (a) to (d) were subjected to various tests. The coal briquettes which mix | blended 10 mass% of the thing weathered by the branch conditions were produced, and the coke strength after dry distillation was measured.

In the coal mixing theory for estimating the coke strength in the related art, it has been considered that the coke strength is mainly determined by the bitlinite average maximum reflectance Ro of the coal and logMF (for example, see Non-Patent Document 2). .). Therefore, a base coal briquettes containing various coals was prepared (Ro = 1.08, logMF = 2.2) so that the weighted average Ro and the weighted average logMF of the whole coal mixture became the average properties of actual operations (Ro = 1.08, logMF = 2.2). 10 mass% of F coal which is coal corresponding to said (A)-(D), and its weathering coal were added, and the blended coal used for a test was produced.

Table 2 shows the penetration distance and maximum flow rate of the coal constituting the base blended coal. In addition, the weighted average constellation value of the base compounding coal is also shown. Here, the weighted average penetration distance of the base blended coal is 6.5 mm, and the penetration distance of F coal is 19.8 mm, so that F bullet corresponds to any of the above conditions (c) and (d).

The regression line which passed the origin was calculated | required based on the log permeation distance of logMF <2.5 which comprises a coal blend, and the logarithmic value of the highest fluidity. The constants a and a 'of equations (2) and (4) were determined to be 2.9, which corresponds to the slope of the obtained regression line. The constant b of Formula (4) was determined to be 3 from 5 times the value of the standard deviation 0.6 in the measurement conditions of the example of this invention. Based on these formulas, the result of having investigated the penetration distance and the highest fluidity of the coal and F coal which comprise a coal blend and the positional relationship of the range of said (A) and (B) is shown to FIG. 10, FIG. 11, respectively. In FIG. 10 and FIG. 11, F shot corresponds to any of the conditions of the ranges (a) and (b).

The weathered coal of F coal was produced by standing for a predetermined time in the heating furnace of the air atmosphere which temperature-controlled F coal at 150 degreeC and 200 degreeC. Moreover, F coal was left still for 12 hours in the heating furnace of the air atmosphere which temperature-controlled to 200 degreeC, and the weathered coal (MF = 0) completely weathered was produced. In addition, weathered coal was also weathered at room temperature in a drum for one year. Table 3 shows the weathering conditions, logMF, and penetration distance of F coal and its weathered coal. It is understood from the weathered F-tan 1 to weathered F-tan 4 that the values of logMF and the penetration distance decrease as the weathering time is longer, and the decreasing rate tends to decrease with time. When the present inventors performed the weathering of coal in various conditions other than an Example, it confirmed that logMF and the penetration distance were monotonically decreasing also in any weathering conditions. Therefore, by controlling weathering conditions appropriately, it is possible to arbitrarily reduce the penetration distance.

Table 4 shows the weighted average property values of the coal briquettes prepared by adding 10 mass% of the weathered coals described in Table 3 to the base coal briquettes described in Table 2. The particle size of the coal briquettes described in Table 4 was pulverized so as to be less than 3 mm to 100 mass%, and the moisture in the entire coal mixture was adjusted to 8 mass%. 16 kg of this blended coal was charged into a distillation can so as to have a bulk density of 750 kg / m 3, and after drying for 6 hours in an electric furnace at a furnace wall temperature of 1050 ° C. with a weight of 10 kg thereon, it was taken out of the furnace and cooled with nitrogen. And coke was obtained. The coke strength of the obtained coke measured the mass ratio of the coke with a particle diameter of 15 mm or more after 15 rpm and 150 rotations based on the rotational strength test method of JISK2151, and computed the mass ratio before rotation as drum strength DI150 / 15. After the CO ₂ hot reaction, the strength (based on ISO18894 method) and the micro strength (MSI + 65) were also measured.

The measurement result of coke strength is shown together in Table 4. Moreover, the relationship between the penetration distance of F coal and drum strength is shown in FIG. When the penetration distance of F coal corresponding to said (A)-(D) was changed in various ways, it confirmed that the intensity | strength of a coal blend changed. Therefore, it was confirmed that the value of the penetration distance measured in the present invention is a factor influencing strength and a factor that cannot be explained by the conventional factor.

Conventionally, since coal melt | dissolves as melting progresses with advancing of weathering, it has been thought that the coke strength at the time of compounding also falls similarly. However, as shown in the present embodiment, the mixed coal 2 in which the weathered F-tan 1, the weathered F-tan 2, the weathered F-tan 6 to weathered F-tan 8 combined with the F coals corresponding to the above (A) to (D) are combined. , The coal briquettes 3 and the coal briquettes 7 to 9 are improved in the coke strength after the distillation than the coal briquettes 1 containing the raw coal. Coal strength 4 and blended coal 5 blended with weathered F-carbon 3 and weathered F-carbon 4 in which the weathering further advanced are hardly changed compared to the mixed coal 1 in which raw coal is blended. And the coal briquette 6 which mix | blended the weathered F coal 5 weathered completely has the remarkable fall of the coke strength after distillation compared with the coal briquette 1 which mix | blended the raw coal. In other words, when the F-coal corresponding to the above items (a) to (d) is weathered, the coke strength is not lowered, but the coke strength is improved once, and thereafter, the coke strength is reduced. Such a result is that the weathering phenomenon, which has been conventionally heard, lowers the coal meltability (logMF) and consequently lowers the coke strength, and decreases the penetration distance described in the present invention. It is considered that this is because two effects of the effect of improving the coke strength exist.

Here, the result of having investigated the penetration distance and the highest fluidity | liquidity of the weathering F coal, and the positional relationship of the range of said (A)-(D) is shown to FIGS. 13-16, respectively. The intensity | strength improvement effect of the weathering F carbon 7 corresponding to any of (m)-(h) range is the highest in this Example. Moreover, it confirmed that the weathering F-tank 6 corresponding to (g) and (a) and the weathering F-tank 6 corresponding only to (a) also had the strength improvement effect with respect to raw coal. In addition, weathering F carbon 8 satisfies all of (e) to (h), but since the MF value is close to the lower limit indicated in (za), the strength improvement effect is smaller than that of weathering F carbon 7, but the strength improvement effect is compared to raw coal. It was admitted to have Therefore, coke strength can be improved by weathering so that the penetration distance and maximum flow rate of a weathering coal become the range prescribed | regulated by this invention.

Moreover, the change of the penetration distance and the highest fluidity | flow rate of the weathering F coal produced by changing processing temperature is shown in FIG. In FIG. 17, it was confirmed that the decrease in the penetration distance was large and the change in the preferred properties was greater in the case of weathering at 200 ° C. than in the case of weathering at 150 ° C. with respect to the decrease in the maximum fluidity.

In the present embodiment, even when F coal corresponding to (a) to (d) is used, the coke strength is compounded by weathering the penetration distance and the maximum flow rate so as to be within the range of the (e) to (r). Confirmed that can be improved.

[Example 2]

In order to investigate the coke strength effect of the weathering coal which weathered only the granulated part of U coal (penetration distance = 46.5mm, logMF = 4.56) corresponding to said (A)-(D) which brings about the strength fall at the time of mixing | blending, The coal briquettes which mix | blended 10 mass% of U coal and weathering U coal with the base blend coal were produced, and the coke strength after dry distillation was measured.

Table 5 shows the weighted average properties of the base blended coal. Here, the base coal is composed of logMF <3.2 coal, its weighted average penetration distance is 9.0 mm, and the U-coal penetration distance is 46.5 mm, so that U-tan is either (c) or (d) above. This also applies to conditions.

The regression line which passed the origin was calculated | required based on the log permeation distance of logMF <2.5 which comprises a coal blend, and the logarithmic value of the highest fluidity. The constants a and a 'of equations (2) and (4) were determined to be 3.8, which coincides with the slope of the obtained regression line. The constant b of Formula (4) was determined to be 3 from 5 times the value of the standard deviation 0.6 in the measurement conditions of the example of this invention. Based on these formulas, the result of having investigated the penetration distance and maximum fluidity of U-coal, and the positional relationship of the range of said (A) and (B) is shown to FIG. 18, FIG. 19, respectively. In FIGS. 18 and 19, the U bullet corresponds to any of the conditions of the ranges (a) and (b).

Without classifying U coal, it left still for 30 minutes in the heating furnace of the air atmosphere adjusted to the temperature at 200 degreeC, and produced the weathered U coal 1. In addition, U bullets are passed through a sieve of 1 mm in the total body, and only U bullets having a particle size of 1 mm or more in the body are weathered under the same conditions, and U bullets having a particle size of less than 1 mm that are not contributing to weathering; Combine and mix well to produce weathered U-tan 2. Table 6 shows the weathering conditions, logMF, and penetration distance of U-shot and weathered coals. It was confirmed that the degree of weathering was different in the weathered U-tan 1 and the weathered U-tan 2, and both the penetration distance and the highest flow rate of the weathered U-tan 1 in which the whole amount was weathered were lowered compared to the weathered U-tan.

Table 7 shows the weighted average property values of the blended coal prepared by adding 10 mass% of U coal to weathered U coal to the base blended coal described in Table 5. The coal briquettes of Table 7 were carbonized by the method similar to Example 1, the coke was produced, and drum strength DI150 / 15 was measured based on the rotational strength test method of JISK2151.

The measurement results of the drum strength are also shown in Table 7. As the present Example shows, the coking strength 11 which mix | blended the U coal corresponding to said (A)-(D) is lower than coking coal 10 which is a base blended coal. Moreover, the coking strength after dry distillation of the mixed coal 12 and the mixed coal 13 which mix | blended the weathered U carbon 1 and the weathered U carbon 2 is improved. Moreover, compared with the coal briquettes 12 and 13, the coal briquettes 13 which mix | blended the weathering U carbon 2 which weathered only granulation have a high coke strength after distillation. This is presumably because the weathering of the U-coal could be effectively reformed by weathering only the granulated portions of the U-coal, which would cause a decrease in strength, without making particulates causing poor adhesion due to preferential weathering.

In the present embodiment, when the coal and the caking additive corresponding to (a) to (d) are weathered to improve the coking property, only the granulated portion which causes the decrease in strength is weathered, thereby suppressing the decrease in strength or the like. It confirmed that the improvement effect can be obtained effectively.

By using the penetration distance measured by this invention, the trademark which improves coking property by weathering can be determined. Since the weathering reaction can also occur spontaneously, it is possible to naturally coke such a brand to improve the coking property without causing an extra cost increase. Moreover, in the above, when improving the coking property of coal by weathering, it is possible to define an appropriate weathering range. Moreover, as a method of weathering, it also discovered that suitable conditions exist which maximize the improvement degree of coking property.

One; Sample 2; Materials having through holes in the upper and lower surfaces
3; Container 5; sleeve
7; Thermometer 8; Heating element
9; Temperature detector 10; Thermostat
11; Gas inlet 12; Gas outlet
13; Expansion rate detecting rod 14; sinker
15; Displacement meter 16; Circular through hole
17; Packed particles 18; Filling column

Claims (20)

As a method of producing a coke by distilling a coal blend composed of two or more coals or a coal blend composed of a caking additive to two or more coals,
Filling the container with a sample of each coal and caking additive constituting the blended coal, and placing a material having a through hole on the upper and lower surfaces on the sample, and heating the sample, the sample of the sample penetrated into the through hole Measure the permeation distance and the highest flowability (logMF) by the Gisseller platometer method,
Selecting the coal whose penetration distance and the highest flow rate fall within a predetermined management range (A),
A part or all of the selected coal is weathered by normal temperature or heat treatment in an oxidizing atmosphere, so that the penetration distance and maximum flow rate of the coal after weathering are within a predetermined management range (B), and the weathered coal is A method for producing a metallurgical coke, characterized by blending. The method of claim 1,
The management range (A) of the penetration distance and maximum flow rate satisfies the following formula (1) and formula (2).
logMF≥2.5 (1)
Penetration distance≥1.3 × a × logMF (2)
(However, "a" measures at least one or more penetration distances and logMF of coal and caking additives in the range of logMF <2.5 among the coals and caking additives constituting the coal blend, and uses the measured value as the origin It is an integer ranging from 0.7 to 1.0 times the coefficient of logMF when a regression line passing through is created.) The method of claim 1,
The management range (A) of the penetration distance and the highest flow rate satisfies the following formula (3) and formula (4).
logMF≥2.5 (3)
Penetration distance? A'xlogMF + b (4)
(However, “a” ”measures at least one or more penetration distances and logMF of coal and binder in the range of logMF <2.5 among the coals and binders constituting the coal blend, and uses the measured values) It is an integer in the range of 0.7 to 1.0 times the coefficient of logMF when a regression line passing through the origin is created, “b” indicates that one or more kinds of the same sample selected from the trademark used for the creation of the regression line are measured multiple times. It is an integer equal to or greater than the average value of the standard deviation at the time and 5 times or less the average value.) The method of claim 1,
The management range (A) is,
The blending ratio of coal or caking additive and coal or caking additive included in the coal blend used for producing coke is determined in advance,
Measure the penetration distance and logMF of the coal or caking additive,
What is determined by determining a range of twice or more as the management range (A) of the penetration distance with respect to the weighted average penetration distance calculated from the penetration distance of the coal or caking additive having a logMF of less than 3.2 and the compounding rate The manufacturing method of the metallurgical coke characterized by the above-mentioned. The method of claim 1,
The control range (A) of the penetration distance is to pulverize the coal or caking additive sample to a particle size of 2 mm or less to 100 mass%, and to fill the pulverized sample to a container having a packing density of 0.8 g / cm 3 and a layer thickness of 10 mm. The glass beads having a diameter of 2 mm on the sample were placed at a layer thickness of more than the penetration distance, and a load was added to the pressure 50 kPa from the top of the glass beads, while the glass beads were 550 from room temperature at a heating rate of 3 ° C / min. A method for producing metallurgical coke, wherein the measured value when heated in an inert gas atmosphere up to 15 ° C is 15 mm or more and logMF is 2.5 or more. 6. The method according to any one of claims 1 to 5,
The said weathering is made to weather so that the penetration distance of the coal after weathering and the highest fluidity may become in the management range (B) prescribed | regulated by following formula (5), The manufacturing method of the metallurgical coke characterized by the above-mentioned.
Penetration distance <1.3 × a × logMF (5)
(However, "a" measures at least one or more penetration distances and logMF of coal and caking additives in the range of logMF <2.5 among the coals and caking additives constituting the coal blend, and uses the measured value as the origin It is an integer ranging from 0.7 to 1.0 times the coefficient of logMF when a regression line passing through is created.) 6. The method according to any one of claims 1 to 5,
The said weathering is made to weather so that the penetration distance and maximum fluidity of the coal after weathering may become in the management range (B) prescribed | regulated by following formula (6), The manufacturing method of the metallurgical coke characterized by the above-mentioned.
Penetration distance <a´ × logMF + b (6)
(However, “a” ”measures at least one or more penetration distances and logMF of coal and binder in the range of logMF <2.5 among the coals and binders constituting the coal blend, and uses the measured values) It is an integer in the range of 0.7 to 1.0 times the coefficient of logMF when a regression line passing through the origin is created, “b” indicates that one or more kinds of the same sample selected from the trademark used for the creation of the regression line are measured multiple times. It is an integer equal to or greater than the average value of the standard deviation at the time and 5 times or less the average value.) The method according to claim 2 or 6,
Said "a" measures the penetration distance and logMF of at least 1 or more types of coal and caking additives in the range of 1.75 <logMF <2.50 among each coal and caking additive which comprise a coal blend, and use the measured value and the origin It is an integer of the range of 0.7-1.0 time of the coefficient of logMF when the regression line which passes through is made. The manufacturing method of the metallurgical coke characterized by the above-mentioned. 8. The method according to claim 3 or 7,
"A""measures the penetration distance and logMF of at least 1 or more types of coal and caking additives in the range of 1.75 <logMF <2.50 among the coals and caking additives which comprise a coal blend, and use the measured value It is an integer of the range of 0.7-1.0 times the coefficient of logMF when the regression line which passes through an origin is created, The manufacturing method of the metallurgical coke characterized by the above-mentioned. 6. The method according to any one of claims 1 to 5,
The blending ratio of the brand of coal or caking additive contained in the coal blend used for the said coke manufacture, and the coal or caking additive of each said brand is decided previously,
Measuring the penetration distance and logMF of the coal or caking additive of each said brand, and calculating the weighted average penetration distance calculated from the penetration distance of the coal or caking additive of each brand whose logMF contained in a coal blend is less than 3.2, and a compounding rate,
The method for producing metallurgical coke, characterized in that the weathering of the coal after the weathering is within the management range (B) is less than twice the weighted average penetration distance. 6. The method according to any one of claims 1 to 5,
The penetration distance of coal after the said weathering is to grind | pulverize a coal sample so that the particle diameter may be 2 mass or less to 100 mass%, and this grind | pulverized sample is filled into a container so that the filling density may be 0.8 g / cm <3>, and the layer thickness shall be 10 mm, Glass beads with a diameter of 2 mm are placed on the sample at a layer thickness of more than the penetration distance, and a load is applied from the upper portion of the glass beads to a pressure of 50 kPa, under an inert gas atmosphere from room temperature to 550 ° C. at a heating rate of 3 ° C./min. The manufacturing method of metallurgical coke characterized by weathering so that it may become in the management range (B) which is less than 15 mm by the measured value at the time of heating. The method according to any one of claims 6 to 11,
The maximum flow rate of the coal after the weathering is logMF≥2.5 and weathering so as to be within the management range (B). 13. The method according to any one of claims 1 to 12,
Oxidizing atmosphere when performing the weathering are O _2, CO _2, The method of coke for metallurgy, characterized in that the gas atmosphere containing at least one component of the H ₂ O. The method of claim 13,
The oxidation atmosphere at the time of performing said weathering is an air atmosphere, The manufacturing method of the metallurgical coke characterized by the above-mentioned. 15. The method according to any one of claims 1 to 14,
The heat treatment at the time of carrying out the said weathering is a processing temperature of 100 degreeC-300 degreeC, and processing time 1 to 120 minutes, The manufacturing method of the metallurgical coke characterized by the above-mentioned. The method of claim 15,
The heat treatment at the time of carrying out the said weathering is 180 degreeC-220 degreeC of processing temperatures, and processing time is 1-30 minutes, The manufacturing method of the metallurgical coke characterized by the above-mentioned. 17. The method according to any one of claims 1 to 16,
When performing said weathering, a part or whole quantity of the coal and caking additive used for coke manufacture are classified previously, and only the particle | grains more than a predetermined | prescribed trunk are weathered, The manufacturing method of the metallurgical coke characterized by the above-mentioned. The method of claim 17,
A method for producing metallurgical coke, characterized in that the predetermined body when classifying coal and caking additives used for coke production during the weathering is selected from the range of 1 mm to 6 mm. The method according to any one of claims 1 to 18,
The method of manufacturing the metallurgical coke, characterized in that the measurement of the penetration distance heats the sample at a predetermined heating rate while applying a constant load from above the material having a through hole on the upper and lower surfaces. The method according to any one of claims 1 to 18,
The method of manufacturing the metallurgical coke, characterized in that the measurement of the penetration distance heats the sample at a predetermined heating rate while maintaining a constant volume of the sample and a material having through holes in the upper and lower surfaces.

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