JP5229362B2 - Method for producing metallurgical coke - Google Patents

Description

  The present invention uses a test method for accurately evaluating the softening and melting characteristics during coal dry distillation, a method for producing metallurgical coke that can reduce the amount of high-grade coal used while maintaining coke strength, or the same composition. The present invention relates to a method for producing metallurgical coke from which high strength coke can be obtained from charcoal.

  Coke used in the blast furnace method, which is most commonly used as a steelmaking method, plays the role of iron ore reducing material, heat source, spacer, and the like. In order to operate the blast furnace stably and efficiently, it is important to maintain the air permeability in the blast furnace, and therefore production of coke having high strength is required. Coke is produced by dry-distilling blended coal in which various types of coal for coke production, which are pulverized and adjusted in particle size, are blended in a coke oven. Coal-producing coal softens and melts in the temperature range of about 300 ° C to 550 ° C during dry distillation, and at the same time foams and expands with the generation of volatile matter. Become. Semi-coke is burned by shrinkage in the process of raising the temperature to around 1000 ° C., and becomes robust coke. Therefore, the adhesion characteristics during softening and melting of coal greatly affect properties such as coke strength and particle size after dry distillation.

  In addition, for the purpose of strengthening the adhesion of coal for coke production (mixed coal), a method of producing coke by adding a caking agent that exhibits high fluidity in the temperature range where coal softens and melts to the blended coal is generally used. Has been done. Here, the binder is specifically tar pitch, petroleum pitch, solvent refined coal, solvent extracted coal, and the like. For these binders, as with coal, the adhesive properties during softening and melting greatly affect the coke properties after dry distillation.

  As described above, the softening and melting characteristics of coal are extremely important because they greatly affect the coke properties and coke cake structure after carbonization, and the investigation of the measurement method has been actively conducted for a long time. In particular, coke strength, which is an important quality of coke, is greatly affected by the properties of coal as the raw material, particularly the degree of coalification and softening and melting characteristics. The softening and melting property is a property of softening and melting when coal is heated, and is usually measured and evaluated by the fluidity, viscosity, adhesiveness, expandability, etc. of the softened melt.

  Among the softening and melting characteristics of coal, a general method for measuring the fluidity at the time of softening and melting includes a coal fluidity test method by the Gieseler plastometer method defined in JIS M8801. In the Gieseler plastometer method, coal pulverized to 425 μm or less is put in a predetermined crucible, heated at a specified temperature increase rate, and the rotation speed of a stirring rod to which a specified torque is applied is read with a scale plate, and ddpm (dial division per minute).

  In contrast to the Gisela plastometer method, which measures the rotational speed of the stirring rod with a constant torque, a method for measuring the torque by the constant rotation method has also been devised. For example, Patent Document 1 describes a method of measuring torque while rotating a rotor at a constant rotational speed.

  In addition, there is a viscosity measurement method using a dynamic viscoelasticity measuring device for the purpose of measuring a physically meaningful viscosity as a softening and melting characteristic (see, for example, Patent Document 2). Dynamic viscoelasticity measurement is the measurement of viscoelastic behavior seen when a force is applied periodically to a viscoelastic body. The method described in Patent Document 2 is characterized in that the viscosity of the softened molten coal is evaluated by the complex viscosity in the parameters obtained by the measurement, and the viscosity of the softened molten coal at an arbitrary shear rate can be measured. .

  Furthermore, as an example of the softening and melting characteristics of coal, an example in which activated carbon or glass beads was used and the coal softening melt adhesion to them was measured was reported. In this method, a small amount of coal sample is heated while being sandwiched between activated carbon and glass beads from above and below, cooled after softening and melting, and the adhesion between coal, activated carbon and glass beads is observed from the appearance.

  A general method for measuring the expansibility of coal during soft melting is the dilatometer method defined in JIS M8801. In the dilatometer method, coal pulverized to 250 μm or less is molded by a specified method, placed in a predetermined crucible, heated at a specified rate of temperature rise, and a detection rod placed on the top of the coal is used to measure changes in coal displacement over time. It is a method to measure.

  Furthermore, in order to simulate the behavior of coal softening and melting in a coke oven, a coal expansibility test method that improves the permeation behavior of gas generated during softening and melting of coal is also known (see, for example, Patent Document 3). This is because the permeable material is placed between the coal bed and the piston, or between the coal bed and the piston and below the coal bed, and the passage of volatiles and liquid substances generated from the coal is increased, thereby reducing the measurement environment. This is a method closer to the expansion behavior in the coke oven. Similarly, a method is also known in which a material having a through-passage is disposed on a coal bed, and the coal is microwave-heated while applying a load to measure the expansibility of the coal (see Patent Document 4).

JP-A-6-347392 JP 2000-304673 A Japanese Patent No. 2855728 JP 2009-204609 A

Morotomi et al .: “Journal of Fuel Association”, Vol. 53, 1974, p. 779-790 Miyazu et al .: “Nippon Steel Pipe Technical Report”, vol. 67, 1975, p. 125-137

  In the manufacture of metallurgical coke, it is common to use blended coal that is a mixture of several brands of coal at a specified ratio. However, if the softening and melting characteristics cannot be evaluated correctly, the required coke strength is satisfied. There is a problem that you can not. When low-strength coke that does not satisfy the specified strength is used in a vertical furnace such as a blast furnace, the amount of powder generated in the vertical furnace is increased, resulting in an increase in pressure loss and the operation of the vertical furnace. May cause troubles such as so-called blow-through, in which the gas flow is locally concentrated.

  Conventional softening and melting characteristics indicators often cannot accurately predict strength. Therefore, empirically, the coke strength is controlled to a certain value or higher by setting the target coke strength higher in advance in consideration of the variation in coke strength resulting from inaccuracy of the evaluation of softening and melting characteristics. Has been done. However, in this method, it is necessary to use a relatively expensive coal having excellent softening and melting characteristics, which is generally known, and to set the average quality of the blended coal to be higher, so that the cost is reduced. Incurs an increase.

  In the coke oven, the coal at the time of softening and melting is softened and melted while being constrained by adjacent layers. Since the thermal conductivity of coal is small, the coal is not uniformly heated in the coke oven, and the state differs from the coke layer, the softened molten layer, and the coal layer from the furnace wall side that is the heating surface. Since the coke oven itself expands somewhat during dry distillation but hardly deforms, the softened and melted coal is constrained by the adjacent coke layer and coal layer.

  In addition, there are many defects around the softened and melted coal, such as voids between coal particles in the coal bed, interparticle voids in the softened molten coal, rough air holes generated by volatilization of the pyrolysis gas, and cracks in the adjacent coke layer. Structure exists. In particular, the crack generated in the coke layer is considered to have a width of several hundred microns to several millimeters, and is larger than the voids and pores between coal particles having a size of about several tens to several hundreds of microns. Therefore, it is considered that coarse defects generated in such a coke layer are not only caused by pyrolysis gas and liquid substances, which are by-products generated from coal, but also permeate softened and melted coal itself. Further, it is expected that the shear rate acting on the softened and melted coal at the time of infiltration varies from brand to brand.

  In order to control the strength of coke more accurately, the inventors need to use the coal softening and melting characteristics measured under conditions simulating the environment in which the coal is placed in the coke oven as an index. I thought. In particular, it was important to measure under conditions where softened and melted coal was constrained, and under conditions simulating the movement and penetration of the melt into the surrounding defect structure. However, the conventional measuring method has the following problems.

  The Giselaer plastometer method is problematic in that it does not take into account any restraint or infiltration conditions for measurement in a state where coal is filled in a container. Moreover, this method is not suitable for the measurement of coal showing high fluidity. The reason is that, when measuring coal showing high fluidity, a phenomenon that the inner wall of the container becomes hollow (Weissenberg effect) occurs, the stirrer may idle, and the fluidity may not be evaluated correctly ( For example, refer nonpatent literature 1.).

  Similarly, the method of measuring the torque by the constant rotation method is deficient in that the constraint condition and the penetration condition are not taken into consideration. In addition, because of the measurement under a constant shear rate, it is impossible to correctly compare and evaluate the softening and melting characteristics of coal as described above.

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

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

  In the coal expansibility test method using the permeable material described in Patent Document 3, the movement of gas and liquid substance generated from coal is considered, but the movement of softened and melted coal itself is considered. There is no problem in that. This is because the permeability of the permeable material used in Patent Document 3 is not large enough to move the softened molten coal. When the present inventors actually performed the test described in Patent Document 3, penetration of the softened molten coal into the permeable material did not occur. Therefore, it is necessary to consider new conditions in order to cause the soft molten coal to penetrate into the permeable material.

  Similarly, Patent Document 4 discloses a method for measuring the expansibility of coal in consideration of the movement of gas and liquid substances generated from coal by arranging a material having a through path on the coal bed. In addition to the problem of restrictions, there is a problem that the conditions for evaluating the infiltration phenomenon in the coke oven are not clear. Furthermore, in Patent Document 4, the relationship between the infiltration phenomenon of the coal melt and the softening and melting behavior is not clear, and there is no suggestion about the relationship between the infiltration phenomenon of the coal melt and the quality of the coke to be produced. It does not describe the production of coke.

  As described above, in the prior art, the fluidity, viscosity, adhesiveness, permeability, and penetration of coal and binder are fully simulated in the environment around coal and binder that has been softened and melted in a coke oven. Softening and melting properties such as expansion rate and pressure during penetration cannot be measured.

  Therefore, the present invention accurately evaluates the softening and melting characteristics of the coal used in the blended coal by measuring the softening and melting characteristics of the coal while simulating the surrounding environment of the softened and melted coal in the coke oven, After clarifying the effect of coal on coke strength, coal that adversely affects coke strength is modified to have favorable softening and melting characteristics, and quality such as strength is excellent using the modified coal. It is an object to provide a method for producing metallurgical coke.

The features of the present invention for solving such problems are as follows.
[1] A method for producing coke by dry-distilling a blended coal comprising two or more types of coal or a blended coal obtained by blending a binder with two or more types of coal,
Filling a container with each coal and caking additive constituting the blended coal as a sample, placing a material having through holes on the upper and lower surfaces on the sample, heating the sample, and penetrating into the through hole Measure the permeation distance of the sample and the maximum fluidity (log MF) by the Gieseler plastometer method,
Select coal whose permeation distance and maximum fluidity fall within the prescribed management range (A),
A part or all of the selected coal is weathered in an oxidizing atmosphere at room temperature or by heat treatment so that the penetration distance and maximum fluidity of the coal after weathering are within a predetermined control range (B), Blended coal,
A method for producing metallurgical coke, characterized in that:
[2] The metallurgical coke manufacturing method according to [1], wherein the permeation distance and the maximum fluidity management range (A) satisfy the following formulas (1) and (2).
logMF ≧ 2.5 (1)
Permeation distance ≧ 1.3 × a × logMF (2)
However, “a” measures at least one permeation distance and log MF of coal and binder in the range of log MF <2.5 among each coal and binder constituting the coal blend, It is a constant in the range of 0.7 to 1.0 times the log MF coefficient when a regression line passing through the origin is created using the measured value.
[3] The metallurgical coke manufacturing method according to [1], wherein the permeation distance and the maximum fluidity management range (A) satisfy the following formulas (3) and (4).
logMF ≧ 2.5 (3)
Permeation distance ≧ a ′ × log MF + b (4)
However, "a '" measures the penetration distance and log MF of at least one kind of coal and binder in the range of log MF <2.5 among the coal and binder that constitute the blended coal, It is a constant in the 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.
“B” is a constant that is not less than the average value of the standard deviation when measuring one or more types of the same sample selected from the brands used to create the regression line, and not more than 5 times the average value. is there.
[4] The metallurgical coke manufacturing method according to [1], wherein the management range (A) is obtained as follows.
Predetermining the coal or caking additive contained in the coal blend used for coke production and the blending ratio of the coal or caking additive,
Measure the penetration distance and log MF of the coal or caking additive,
The control range (A) of the permeation distance is a range more than twice the weighted average permeation distance calculated from the permeation distance and the blending rate of coal or caking material having a log MF of less than 3.2. decide.
[5] The permeation distance management range (A) is a coal or binder sample pulverized so that a particle size of 2 mm or less is 100 mass%, and the pulverized sample is packed at a packing density of 0.8 g / cm ³ . Fill the container so that the thickness is 10 mm and use it as a sample. Place a glass bead with a diameter of 2 mm on the sample with a layer thickness equal to or greater than the penetration distance, and apply a load from the top of the glass bead to a pressure of 50 kPa. However, the measured value when heated in an inert gas atmosphere from room temperature to 550 ° C. at a temperature rising rate of 3 ° C./min is 15 mm or more and the log MF is 2.5 or more, [1] A method for producing metallurgical coke as described in 1.
[6] The weathering is performed such that the coal penetration distance and the maximum fluidity after weathering are within the control range (B) defined by the following formula (5), [1] to [5] The manufacturing method of the coke for metallurgical products in any one.
Penetration distance <1.3 × a × logMF (5)
However, “a” measures at least one permeation distance and log MF of coal and binder in the range of log MF <2.5 among each coal and binder constituting the coal blend, It is a constant in the range of 0.7 to 1.0 times the log MF coefficient when a regression line passing through the origin is created using the measured value.
[7] The weathering is performed such that the infiltration distance and the maximum fluidity of the coal after weathering are within the control range (B) defined by the following formula (6), [1] to [5] The manufacturing method of the coke for metallurgical products in any one.
Permeation distance <a ′ × log MF + b (6)
However, "a '" measures the penetration distance and log MF of at least one kind of coal and binder in the range of log MF <2.5 among the coal and binder that constitute the blended coal, It is a constant in the 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.
b is a constant that is not less than the average value of the standard deviation when measuring one or more types of the same sample selected from the brands used for creating the regression line, and not more than 5 times the average value.
[8] The penetration distance of at least one or more types of coal and caking material in the range of 1.75 <logMF <2.50 among the coal and caking material constituting the blended coal, The log MF is measured, and a constant in the range of 0.7 to 1.0 times the log MF coefficient when a regression line passing through the origin is created using the measured value [2] or [6] ] The manufacturing method of the coke for metallurgical products of description.
[9] The penetration distance of at least one or more coals and binders in the range of 1.75 <logMF <2.50 among the coals and binders constituting the blended coal, wherein “a ′” is And log MF, and a constant in the range of 0.7 to 1.0 times the log MF coefficient when a regression line passing through the origin is created using the measured value [3] or [ [7] A method for producing metallurgical coke according to [7].
[10] The brand of coal or caking additive contained in the blended coal used for coke production and the blending ratio of coal or caking additive of each brand are determined in advance,
The weighted average calculated by measuring the penetration distance and log MF of each brand of coal or binder, and calculating from the penetration distance and blending ratio of each brand of coal or binder with a log MF of less than 3.2. Calculate the penetration distance,
Any one of [1] to [5], wherein the weathered coal is infiltrated so that a permeation distance of the coal is within a control range (B) that is less than twice the weighted average permeation distance. A method for producing metallurgical coke as described in 1.
[11] The coal penetration distance after weathering is such that the coal sample is pulverized so that the particle size of 2 mm or less is 100 mass%, and the pulverized sample has a packing density of 0.8 g / cm ³ and a layer thickness of 10 mm. The sample is filled in a container, and a glass bead with a diameter of 2 mm is placed on the sample with a layer thickness equal to or greater than the permeation distance, while a load is applied from the top of the glass bead to a pressure of 50 kPa, and the rate of temperature rise Weathering to be within the control range (B) of less than 15 mm in the measured value when heated in an inert gas atmosphere from room temperature to 550 ° C. at 3 ° C./min,
The method for producing metallurgical coke according to any one of [1] to [5].
[12] It is weathered so that the maximum fluidity of coal after weathering is log MF ≧ 2.5 and within the control range (B), according to any one of [6] to [11] A method for producing metallurgical coke.
[13] Any one of [1] to [12], wherein the oxidizing atmosphere when the weathering is performed is a gas atmosphere containing one or more components of O ₂ , CO ₂ , and H ₂ O. A method for producing metallurgical coke as described in 1.
[14] The method for producing metallurgical coke according to [13], wherein an oxidizing atmosphere when the weathering is performed is an air atmosphere.
[15] The metallurgy according to any one of [1] to [14], wherein the heat treatment at the time of weathering is a treatment temperature of 100 ° C. to 300 ° C. and a treatment time of 1 to 120 minutes. Coke production method.
[16] The method for producing metallurgical coke according to [15], wherein the heat treatment at the time of the weathering is a treatment temperature of 180 ° C. to 220 ° C. and a treatment time of 1 to 30 minutes.
[17] When performing the weathering, 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. [1] Thru | or the manufacturing method of the metallurgical coke in any one of [16].
[18] In the above [17], when the weathering is performed, a predetermined sieve mesh for classifying coal and caking additive used for coke production is selected from a range of 1 mm to 6 mm. The manufacturing method of the metallurgical coke as described.
[19] The measurement of the penetration distance includes heating the sample at a predetermined heating rate while applying a constant load from above the material having through holes on the upper and lower surfaces. ] The manufacturing method of the metallurgical coke in any one of.
[20] The measurement of the penetration distance includes heating the sample at a predetermined heating rate while maintaining the sample and the material having through holes in the upper and lower surfaces at a constant volume. ] The manufacturing method of the metallurgical coke in any one of.

  According to the present invention, the defect structure existing around the coal softening and melting layer in the coke oven, particularly the coke layer adjacent to the softening and melting layer, which is considered to have a great influence on the coal softening and melting characteristics in the coke oven. It is possible to evaluate the softening and melting characteristics of coal or binder in the state of simulating the effect of existing cracks and appropriately reproducing the restraint conditions around the softened melt in the coke oven. As a result, it is possible to predict the generation of defects derived from coal or caking material exhibiting excessive fluidity, which could not be detected by conventional methods for evaluating softening and melting properties, and to adversely affect coke quality. The binding material can be specified. Since coal having undesirable softening and melting characteristics can be modified by weathering so as to have softening and melting characteristics preferable for coke production, there is an effect that reduction of coke strength is reduced and improvement of coke strength is realized.

It is the schematic which shows an example of the apparatus which measures a softening-melting characteristic, applying a fixed load to the coal and binder material used by this invention, and the material which has a through-hole in the upper and lower surfaces. It is the schematic which shows an example of what has a circular through-hole among the materials which have a through-hole in the upper and lower surfaces used by this invention. It is the schematic which shows an example of a spherical particle packing layer among the materials which have a through-hole in the upper and lower surfaces used by this invention. It is the schematic which shows an example of a cylindrical packing layer among the materials which have a through-hole in the upper and lower surfaces used by this invention. In the normal formulation specified in the present invention, the strength is reduced, but the penetration distance and the maximum fluidity range (corresponding to (A)) where coal and caking additive that can suppress the strength reduction by weathering exist, It is a schematic diagram showing a suitable weathered coal penetration distance and maximum fluidity range (corresponding to (e)) and a most preferred weathered coal penetration distance and maximum fluidity range (corresponding to (i)). In the normal formulation specified in the present invention, the strength is reduced, but the penetration distance and the maximum fluidity range (corresponding to (b)) where coal and caking additive that can suppress the strength reduction by weathering exist, It is a schematic diagram which shows the range of suitable penetration distance and the maximum fluidity of weathered coal (corresponding to (f)), and the most suitable range of weathered coal and range of maximum fluidity (corresponds to (ri)). In the normal formulation specified in the present invention, the strength is reduced, but the penetration distance and the maximum fluidity range (corresponding to (c)) where coal and caking additive that can suppress the strength reduction by weathering are present, It is a schematic diagram showing a suitable weathered coal penetration distance and maximum fluidity range (corresponding to (g)) and a most preferred weathered coal penetration distance and maximum fluidity range (corresponding to (i)). In the normal formulation specified in the present invention, the strength is reduced, but the penetration distance and the maximum fluidity range (corresponding to (d)) in which coal and caking additive that can suppress the strength reduction by weathering exist, It is a schematic diagram showing a suitable weathered coal penetration distance and maximum fluidity range (corresponding to (h)) and a most preferred weathered coal penetration distance and maximum fluidity range (corresponding to (i)). It is a graph which shows the measurement result of the penetration distance of a coal softening melt measured by the present invention. It is a graph which shows the positional relationship with the osmosis | permeation distance and the maximum fluidity of coal and F coal which comprise the combination coal produced in Example 1, and the range of the osmosis | permeation distance and the maximum fluidity applicable to (A). It is a graph which shows the positional relationship with the osmosis | permeation distance and the maximum fluidity of coal and F coal which comprise the combination coal produced in Example 1, and the range of the osmosis | permeation distance and maximum fluidity applicable to (B). 3 is a measurement result of coke drum strength measured in Example 1. FIG. The positional relationship between the penetration distance and the maximum fluidity of weathered F charcoal produced in Example 1 and the range of the penetration distance and maximum fluidity corresponding to (e) (the range below the line of formula (1)) is shown. It is a graph. The positional relationship between the penetration distance and maximum fluidity of weathered F charcoal produced in Example 1 and the range of penetration distance and maximum fluidity corresponding to (f) (the range below the line of formula (2)) is shown. It is a graph. Penetration distance and maximum fluidity of weathered F coal produced in Example 1 and range of penetration distance and maximum fluidity corresponding to (g) (weighted average penetration of base blend coal consisting of coal with log MF less than 3.2) It is a graph which shows the positional relationship with the distance below the straight line of the penetration distance 13mm which is twice the distance 6.5mm. The graph which shows the positional relationship of the osmosis | permeation distance of the weathered F charcoal produced in Example 1, and the maximum fluidity, and the osmosis | permeation distance corresponding to (h), and the range of the maximum fluidity (range below the osmosis | permeation distance of 15 mm). It is. It is a graph which shows the penetration distance of the weathered F coal produced by changing process temperature in Example 1, and the change of the maximum fluidity. It is a graph which shows the positional relationship of the osmosis | permeation distance and the maximum fluidity of U charcoal used in Example 2, and the range of the osmosis | permeation distance and the highest fluidity applicable to (A). It is a graph which shows the positional relationship of the osmosis | permeation distance and the maximum fluidity of U charcoal used in Example 2, and the range of the osmosis | permeation distance and the highest fluidity applicable to (b). It is the schematic which shows an example of the apparatus which measures a softening-melting characteristic, keeping the coal sample used by this invention, and the material which has a through-hole in an upper and lower surface at a fixed volume.

The present inventors have made it possible to measure the softening and melting characteristics in a state of simulating the surrounding environment of the softened and melted coal in the coke oven, and eagerly researched the relationship between the measured softening and melting characteristics “penetration distance” and coke strength. The following findings were obtained.
・ There is a difference in softening and melting characteristics according to the method of the present invention measured in a state simulating the environment around the softened and melted coal even if there is little difference in the softening and melting characteristics reported so far. .
When coke is produced by blending coal having a difference in softening and melting characteristics measured by the method of the present invention, the coke strengths thereof are also different.
Based on the above findings, the present inventors have found a method for modifying coal that has an adverse effect on coke strength to have favorable softening and melting characteristics, and have reached the present invention.

  FIG. 1 shows an example of a measuring device for softening and melting characteristics (penetration distance) used in the present invention. FIG. 1 shows an apparatus for heating a coal sample by applying a constant load to the coal sample and a material having through holes on the upper and lower surfaces. The lower part of the container 3 is filled with coal to form a sample 1, and a material 2 having through holes on the upper and lower surfaces is arranged on the sample 1. The sample 1 is heated to the softening and melting start temperature or more, the sample is infiltrated into the material 2 having through holes on the upper and lower surfaces, and the permeation distance is measured. Heating is performed in an inert gas atmosphere. Here, the inert gas refers to a gas that does not react with coal in the measurement temperature range, and representative gases include argon gas, helium gas, nitrogen gas, and the like. Note that the penetration distance may be measured by heating the material having coal and the through-holes while maintaining a constant volume. An example of a measuring device for softening and melting characteristics (penetration distance) used in that case is shown in FIG.

  When a constant load is applied to the sample 1 shown in FIG. 1 and the material 2 having through holes on the upper and lower surfaces and the sample 1 is heated, the sample 1 expands or contracts, and the material 2 having the through holes on the upper and lower surfaces Move in the direction. Therefore, it is possible to measure the expansion coefficient at the time of sample penetration through the material 2 having through holes on the upper and lower surfaces. As shown in FIG. 1, an expansion coefficient detecting rod 13 is arranged on the upper surface of a material 2 having through holes on the upper and lower surfaces, a weight 14 for applying a load is placed on the upper end of the expansion coefficient detecting rod 13, and a displacement meter 15 is placed thereon. And measure the expansion rate. The displacement meter 15 may be one that can measure the expansion range (-100% to 300%) of the expansion coefficient of the sample. Since it is necessary to maintain the inside of the heating system in an inert gas atmosphere, a non-contact type displacement meter is suitable, and it is desirable to use an optical displacement meter. The inert gas atmosphere is preferably a nitrogen atmosphere. In the case where the material 2 having through holes on the upper and lower surfaces is a particle packed layer, the expansion coefficient detecting rod 13 may be buried in the particle packed layer, and therefore the material 2 having the through holes on the upper and lower surfaces and the expansion coefficient detecting rod 13. It is desirable to take measures to sandwich the board between the two. The load to be applied is preferably evenly applied to the upper surface of the material having through holes on the upper and lower surfaces arranged on the upper surface of the sample, and 5 to 80 kPa with respect to the area of the upper surface of the material having the through holes on the upper and lower surfaces, It is desirable to apply a pressure of preferably 15 to 55 kPa, most preferably 25 to 50 kPa. This pressure is preferably set based on the expansion pressure of the softened and molten layer in the coke oven, but as a result of examining the reproducibility of the measurement results and the ability to detect the difference in brands in various coals, It has been found that a slightly higher level of about 25 to 50 kPa is most preferable as a measurement condition.

  It is desirable to use a heating means that can heat at a predetermined rate of temperature rise while measuring the temperature of the sample. Specifically, an electric furnace, an external heating type that combines a conductive container and high frequency induction, or an internal heating type such as a microwave. When the internal heating method is adopted, it is necessary to devise a method for making the temperature in the sample uniform, and for example, it is preferable to take measures to increase the heat insulation of the container.

  The heating rate needs to match the heating rate of coal in the coke oven for the purpose of simulating the softening and melting behavior of coal and binder in the coke oven. Although the heating rate of coal in the softening and melting temperature range in the coke oven varies depending on the position in the furnace and operating conditions, it is generally 2 to 10 ° C / min, and the average heating rate should be 2 to 4 ° C / min. The most desirable is about 3 ° C./min. However, in the case of coal with low fluidity such as non-slightly caking coal, the permeation distance and expansion are small at 3 ° C./min, which may make detection difficult. It is generally known that coal is improved in fluidity by a Gisela plastometer by rapid heating. Therefore, for example, in the case of coal with an infiltration distance of 1 mm or less, measurement may be performed with the heating rate increased to 10 to 1000 ° C./min in order to improve detection sensitivity.

  About the temperature range which heats, since the objective is evaluation of the softening and melting characteristic of coal and a binder, what is necessary is just to be able to heat to the softening and melting temperature range of coal and a binder. Considering the softening and melting temperature range of coal and caking material for coke production, a predetermined heating rate in the range of 0 ° C (room temperature) to 550 ° C, preferably in the range of 300 to 550 ° C, which is the softening and melting temperature of coal. You can heat with.

  The material having through holes on the upper and lower surfaces is preferably one that can measure or calculate the transmission coefficient in advance. Examples of the form of the material include an integrated material having a through hole and a particle packed layer. Examples of the integrated material having a through hole include a material having a circular through hole 16 as shown in FIG. 2, a material having a rectangular through hole, and a material having an indeterminate shape. The particle packed layer is roughly divided into a spherical particle packed layer and a non-spherical particle packed layer. The spherical particle packed layer is composed of beads packed particles 17 as shown in FIG. 3, and the non-spherical particle packed layer is not suitable. Examples thereof include regular particles and those made of filled cylinders 18 as shown in FIG. In order to maintain the reproducibility of the measurement, it is desirable 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 simplify the measurement. Therefore, the use of a spherical particle packed bed is particularly desirable for the material having through holes on the upper and lower surfaces used in the present invention. The material having the through holes on the upper and lower surfaces is not particularly specified as long as the shape hardly changes to the coal softening and melting temperature range, specifically up to 600 ° C., and does not react with coal. Moreover, the height should just be sufficient height for the melt of coal to osmose | permeate, and what is necessary is just about 20-100 mm when heating a coal layer of thickness 5-20 mm.

The transmission coefficient of the material having through holes on the upper and lower surfaces needs to be set by estimating the transmission coefficient of coarse defects present in the coke layer. In the case where the transmission coefficient is 1 × 10 ⁸ to 2 × 10 ⁹ m ⁻² as a result of repeated investigations by the present inventors, such as consideration of coarse defect constituent factors and estimation of the size, which are particularly desirable for the present invention. Was found to be optimal. This transmission coefficient is derived based on the Darcy rule expressed by the following equation (7).
ΔP / L = K · μ · u (7)
Here, ΔP is the pressure loss [Pa] in the material having through holes on the upper and lower surfaces, L is the height [m] of the material having the through holes, K is the transmission coefficient [m ⁻² ], μ is the fluid. Viscosity [Pa · s], u is fluid velocity [m / s]. For example, when a glass bead layer having a uniform particle diameter is used as a material having through holes on the upper and lower surfaces, in order to have the above-mentioned preferable transmission coefficient, glass beads having a diameter of about 0.2 mm to 3.5 mm are used. It is desirable to choose, most preferably 2 mm.

The coal and binder used as the measurement sample are pulverized in advance and filled to a predetermined layer thickness with a predetermined packing density. The pulverized particle size may be the particle size of the coal charged in the coke oven (the ratio of particles having a particle size of 3 mm or less is about 70 to 80% by mass), and pulverization is performed so that the particle size of 3 mm or less is 70% by mass or more. However, it is particularly preferable to use a pulverized product in which the total amount is pulverized to a particle size of 2 mm or less in consideration of measurement with a small apparatus. The density for filling the pulverized product can be 0.7 to 0.9 g / cm ³ in accordance with the packing density in the coke oven. As a result of studying reproducibility and detection power, 0.8 g / cm ³ is preferable. I found out. Further, the layer thickness to be filled can be 5 to 20 mm based on the thickness of the softened and melted layer in the coke oven, but as a result of studying reproducibility and detection power, the layer thickness should be 10 mm. I found it preferable.

In the measurement of the above penetration distance, typical measurement conditions are described below.
(1) Coal or caking material is pulverized so that the particle size of 2 mm or less is 100% by mass, and the pulverized coal or caking material has a packing density of 0.8 g / cm ³ and a layer thickness of 10 mm. Create a sample by filling the container like
(2) A glass bead having a diameter of 2 mm is arranged on the sample so as to have a layer thickness of an infiltration distance or more,
(3) Heating in an inert gas atmosphere from room temperature to 550 ° C. at a heating rate of 3 ° C./min while applying a load from the top of the glass beads to 50 kPa,
(4) The penetration distance of the molten sample that has penetrated into the glass bead layer is measured.

  It is inherently desirable that the penetration distance of the softened melt of coal and caking can be measured continuously during heating. However, continuous measurement is difficult due to the influence of tar generated from the sample. The expansion and infiltration phenomenon of coal by heating is irreversible, and once expanded and infiltrated, the shape is maintained even after cooling, so after the coal melt has been infiltrated, the entire container is cooled, You may make it measure how much it penetrate | infiltrated during the heating by measuring the penetration distance after cooling. For example, it is possible to take out a material having through holes on the upper and lower surfaces from the cooled container and directly measure with a caliper or a ruler. Further, when particles are used as the material having through holes on the upper and lower surfaces, the softened melt that has permeated the interparticle voids fixes the entire particle layer up to the permeated portion. Therefore, if the relationship between the mass and height of the particle packed bed is obtained in advance, the mass of the non-adhered particles is measured after the infiltration, and the mass of the adhering particles is derived by subtracting from the initial mass. And the penetration distance can be calculated therefrom.

  The superiority of such penetration distance is not only assumed in principle based on the measurement method close to the coke oven conditions, but is also clear from the results of investigating the effect of penetration distance on coke strength. became. In fact, according to the evaluation method of the present invention, even if the coal has the same log MF (the common logarithm of the maximum fluidity by the Gieseller Plastometer method), it is clear that there is a difference in the penetration distance depending on the brand. It was confirmed that the effect on coke strength when coke was produced by blending coal with different distances was also different.

In the evaluation of the softening and melting characteristics using a conventional Gieseller plastometer, it has been considered that coal exhibiting high fluidity has a higher effect of adhering coal particles. On the other hand, by investigating the relationship between permeation distance and coke strength, when coal with extremely large permeation distance is blended, coarse defects are left at the time of coking and a thin pore wall structure is formed. Was found to be lower than the value expected from the average quality of the blended coal. This is presumed to be because coal with a too long permeation distance permeates significantly between surrounding coal particles, so that the portion where the coal particles existed itself becomes a large cavity and becomes a defect. In particular, in the evaluation of softening and melting characteristics with a Gieseler plastometer, it was found that the amount of coarse defects remaining in the coke differs depending on the penetration distance in coal that exhibits high fluidity. This relationship was similarly observed for the binder.
As a result of repeated studies by the present inventors, the range of coal or caking additive that causes a decrease in coke strength when used in a coke production raw material is as follows. It was found that it is effective to prescribe in 4 ways.

(A) A range defined by the following formula (1) and formula (2).
logMF ≧ 2.5 (1)
Permeation distance ≧ 1.3 × a × logMF (2)
However, “a” measures at least one permeation distance and log MF of coal and binder in the range of log MF <2.5 among each coal and binder constituting the coal blend, It is a constant in the range of 0.7 to 1.0 times the log MF coefficient when a regression line passing through the origin is created using the measured value.

(B) A range defined by the following formula (3) and formula (4).
logMF ≧ 2.5 (3)
Permeation distance ≧ a ′ × log MF + b (4)
However, "a '" measures the permeation distance and maximum fluidity of at least one kind of coal and caking additive in the range of logMF <2.5 among the coal and caking additive constituting the blended coal. The constant is in the range of 0.7 to 1.0 times the logMF coefficient when a regression line passing through the origin is created using the measured value. “B” is a constant that is not less than the average value of the standard deviation when measuring one or more types of the same sample selected from the brands used to create the regression line, and not more than 5 times the average value. is there.

  (C) If the brand and blending ratio of the blended coal used for coke production can be determined in advance, calculate from the penetration distance and blending ratio of each brand of coal or log binder containing less than 3.2 log MF More than twice the weighted average penetration distance. At this time, the average permeation distance is preferably obtained by a weighted average considering the blending rate, but a simple average value can be substituted.

(D) A coal sample prepared to have a particle size of 2 mm or less and a particle size of 100 mass% is filled in a container with a packing density of 0.8 g / cm ³ to a thickness of 10 mm, and glass beads having a diameter of 2 mm are used as materials having through holes. The penetration distance is 15 mm or more and the log MF is 2.5 or more when measured by heating to 550 ° C. at a heating rate of 3 ° C./min with a load of 50 kPa.

  Here, the method of determining the four types of management values (i) to (d) described above is that the value of the permeation distance is a material having a set measurement condition, for example, a load, a heating rate, and a through hole. As a result of considering that there are cases where the measurement conditions differ from the example described in the present invention, the management values of (a) to (c) are changed. This is based on the finding that the decision method is effective.

  In addition, the constants a and a ′ in the formulas (2) and (4) used for determining the range of (A) and (B) are at least one penetration of coal in the range of logMF <2.5. The distance and maximum fluidity are measured, and the measured values are used to determine a range of 0.7 to 1.0 times the log MF coefficient when a regression line passing through the origin is created. This is because, in the range of log MF <2.5, there is an almost positive correlation between the maximum coal flow rate and the penetration distance. This is because the brand is biased. As a result of intensive studies, the present inventors have a brand that falls within a range of 1.3 times or more the penetration distance determined according to the log MF value of coal according to the above regression equation, which leads to a decrease in strength. Thus, it was decided to define the range by the formulas (1) and (2). In addition, based on the understanding that brands that deviate positively beyond measurement error are not preferable from the above regression equation, 1 to 5 times the standard deviation when the same sample was measured multiple times was added to the above regression equation. It was found that the brand corresponding to the range above the value was a brand that caused a decrease in strength, and the range was defined by the equations (3) and (4). Accordingly, the constant b may be 1 to 5 times the standard deviation when the same sample is measured a plurality of times, and is about 0.6 to 3.0 mm under the measurement conditions described in the present invention. At this time, both the expressions (2) and (4) define the range of the penetration distance that causes the strength to decrease based on the log MF value of the coal. This is because, as the MF increases, the penetration distance generally increases, so how much deviation is important from the correlation. In addition, you may use the method of the linear regression by the well-known least square method for preparation of a regression line. The larger the number of coals used in the regression, the better the error in the regression. In particular, for brands with small MF, the penetration distance is small and the error tends to be large, so it is particularly preferable to obtain a regression line using one or more kinds of coal in the range of 1.75 <log MF <2.50.

  Here, the reason why both the constants a and a ′ and b define the range is that by reducing these values, it is possible to more reliably detect coal that causes a decrease in strength. Can be adjusted according to operational requirements. However, if this value is too small, too much coal is estimated to have an adverse effect on coke strength, and it may be misunderstood that even if it does not cause strength reduction, it will cause strength reduction. Therefore, a and a ′ are preferably 0.7 to 1.0 times the slope of the regression line, and b is 1 to 1 of the standard deviation when the same sample is measured a plurality of times. 5 times is preferable.

  Coal or caking additive used for blended coal is usually used by measuring various grades for each brand in advance. Similarly, the penetration distance may be measured in advance for each brand lot. The average penetration distance of the blended coal is measured in advance for each brand, and the value may be averaged according to the blending ratio, or the blended coal may be measured to measure the penetration distance. . This makes it possible to select a brand having an extremely large penetration distance with respect to the average penetration distance of the blended coal. The blended coal used for coke production may contain oils, powdered coke, petroleum coke, resins, waste, etc. in addition to coal or caking additive.

  When the coal and caking additive corresponding to the above (i) to (d) are used as coke raw coal under normal pretreatment conditions, coarse defects remain during coking, and the structure structure of thin pore walls This causes a reduction in coke strength. Therefore, it is convenient and effective as a means for maintaining the coke strength to take measures to limit the blending ratio of the brand and the binder. However, from the viewpoint of the stable procurement of raw materials, in the current coke production that is oriented to blending multi-country brands, even coal or caking materials that fall under (i) to (d) There are many cases where it is forced to use.

  Even when the present inventors use a blended coal obtained by blending coal and a caking additive corresponding to the above (a) to (d) as a coke raw material, (a) to (d) It has been found that coal and caking materials that fall under these conditions can be naturally weathered in advance or by heat treatment, and strength reduction can be suppressed by controlling the values of permeation distance and maximum fluidity. . When coal is exposed to air after it has been mined, its properties change as it gradually pulverizes or loses its luster. Moreover, caking property (maximum fluidity etc.), a calorific value, and coking property also fall, and the quality as raw coal for cokes becomes inferior. Such a phenomenon is called weathering. When coal is weathered, the permeation distance decreases with the progress of weathering. As a result of repeated extensive research by the present inventors, when the coal corresponding to the above (i) to (d) is forcibly weathered in advance naturally or by heat treatment, the penetration distance of the coal after weathering and It has been found that the reduction in coke strength can be effectively suppressed by controlling the weathering method or the degree of progress so that the maximum fluidity falls within the following ranges (e) to (l).

(E) Weathering is performed so that the penetration distance and maximum fluidity of weathered coal are within the range defined by the following formula (5).
Penetration distance <1.3 × a × logMF (5)
(F) Weathering is performed so that the penetration distance and maximum fluidity of weathered coal are within the range defined by the following formula (6).
Permeation distance <a ′ × log MF + b (6)
Here, a, a ′, and b can be obtained by the same method as in the determination of the ranges (a) and (b).

  (G) When the brand name and blending ratio of the coal blend used for coke production can be determined in advance, calculation is based on the penetration distance and blending ratio of each brand coal or caking material with a log MF of less than 3.2. Weathered to be less than twice the weighted average penetration distance.

(H) A sample prepared so that the penetration distance of weathered charcoal has a diameter of 2 mm or less and a particle size of 100 mass% is filled into a container with a packing density of 0.8 g / cm ³ to a thickness of 10 mm, and a diameter is used as a material having through holes Using 2 mm glass beads, a load of 50 kPa is applied, and weathering is performed so that the penetration distance is less than 15 mm when measured by heating to 550 ° C. at a heating rate of 3 ° C./min.

  (Li) Weathering is performed so that the penetration distance of weathered coal satisfies at least one of (e) to (h) and the maximum fluidity is in a range of logMF ≧ 2.5.

  Here, as a result of repeated extensive research by the present inventors, it has been found that the properties of weathered coal are desirable for improving the coke strength at the time of blending with a small permeation distance and a high maximum fluidity. . The reason for this is that the lower permeation distance is desirable as described above, but the larger maximum fluidity is desirable because the particles adhere well when the coal is softened and melted. is there. Therefore, it is possible to produce high-strength coke by controlling the weathering method or the degree of progress so that the penetration distance of weathered coal satisfies at least one of (e) to (h) and the maximum fluidity does not decrease as much as possible. This is desirable. Therefore, as described in (i), by setting the maximum fluidity of weathered coal to a range of logMF ≧ 2.5, a decrease in strength can be effectively suppressed without causing poor adhesion.

  In the above, (i) to (d), the normal blending causes a decrease in strength, but the penetration distance and the maximum fluidity range in which coal and caking additive that can suppress the strength decrease by weathering exist, Summarize the suitable weathered coal penetration distance and maximum fluidity range corresponding to (e) to (h) and the most suitable weathered coal penetration distance and maximum fluidity range applicable to (i). These are schematically shown in FIGS. (Li) is included in the range of (e) to (h).

  It is generally known that the coal weathering speed depends on oxygen concentration, atmospheric pressure, temperature, coal particle size, coal moisture, and the like. When the coal is weathered in order to control the permeation distance and the maximum fluidity, the above-mentioned weathering factors may be appropriately controlled.

  The inventors of the present invention have found that the permeation distance and the rate of decrease in the maximum fluidity differ depending on the weathering conditions by conducting an experiment in which coal is weathered by changing the above-mentioned weathering factors. As a result of repeated examinations with various weathering conditions, a suitable weathering method was found in producing weathered coal having properties corresponding to (i). The specific method will be described below.

The atmosphere for weathering needs to be an oxidizing atmosphere. Here, the oxidizing atmosphere is an atmosphere containing oxygen or containing a substance capable of dissociating and oxidizing oxygen. There are an infinite number of such conditions, but considering the ease of acquisition and control, a gas atmosphere containing O ₂ , CO ₂ , and H ₂ O is desirable. In a gas atmosphere, the oxidizing power can be easily adjusted with the concentration and pressure of the oxidizing gas, and the progress of the oxidation of coal and binder can be quickly stopped by replacing it with an inert gas after the treatment. Therefore, the processing time can be arbitrarily set. Here, the higher the concentration of the oxidizing gas and the higher the pressure, the faster the weathering proceeds. On the other hand, in the case of an oxidizing liquid atmosphere, it is difficult to quickly separate from coal and caking additive after the weathering treatment, which is not preferable for controlling the degree of weathering progress.

  In addition, the cheapest, easy, and available mass atmosphere is air in the atmosphere. Therefore, when industrial mass processing is required, it is desirable to use air in the atmosphere as the oxidizing atmosphere.

  The treatment temperature at the time of weathering can be any of the range from the normal temperature at which coal weathering occurs to the temperature just before coal shows softening and melting. Since the progress of weathering becomes faster as the temperature becomes higher, the processing time required for producing weathered coal having properties corresponding to (e) to (ri) becomes shorter as the processing temperature becomes higher. As a result of investigating the influence of the treatment temperature on the weathered coal properties, the present inventors have found that the higher the treatment temperature, the faster the decrease rate of the penetration distance with respect to the decrease rate of the maximum fluidity of the weathered coal. It was. That is, it is possible to preferentially lower the permeation distance without lowering the maximum fluidity of weathered coal as much as possible at higher temperatures. Therefore, it has been found that high temperature and short time are effective as conditions for processing temperature and processing time suitable for producing weathered coal having properties corresponding to (i).

On the other hand, if coal is rapidly weathered, there is a risk of spontaneous ignition due to oxidation heat generation, so it is necessary to take measures to prevent spontaneous ignition such as watering. Further, if the treatment temperature is too high, the weathering speed is high, and it becomes difficult to control the properties after the weathering treatment. Further, since coal begins to emit volatile components by thermal decomposition from around 300 ° C., the softening and melting characteristics change. In addition, the weathering treatment in the temperature range where volatile matter is released involves the danger of explosion because flammable gas exists under heating conditions in an oxidizing atmosphere.

  For the reasons described above, the treatment temperature during weathering is preferably 100 to 300 ° C., and the treatment time is preferably 1 to 120 minutes. Most preferably, the treatment temperature during weathering is 180 ° C. to 220 ° C., and the treatment time is 1 to 30 minutes.

  As the particle size of coal during the weathering treatment, part or all of the coal and caking additive corresponding to (i) to (d) are classified in advance, and only particles having a predetermined mesh size or more are weathered. Is desirable. The reason for this can be explained as follows.

  The reason why the coal and the binder corresponding to (i) to (d) reduce the coke strength at the time of blending is to leave coarse defects at the time of coking and to form a thin pore wall structure. is there. The present inventors have found that even in the case of coal and caking materials corresponding to (i) to (d), in the case of fine particles, coarse defects are not formed, so that the coke strength is not lowered. ing.

  Further, since fine particles have a large specific surface area during the weathering treatment, weathering proceeds preferentially over coarse particles. Therefore, when weathering all the particles of coal and caking additive corresponding to (i) to (d), if coarse particles that cause strength reduction are appropriately weathered so as to correspond to (e) to (ri), On the contrary, the fine particles are too weathered and the maximum fluidity is out of the range of logMF ≧ 2.5, which leads to poor adhesion and causes a reduction in coke strength.

  Therefore, only the coal and coarse-grained parts of the binder corresponding to (i) to (d), which cause a reduction in coke strength, are taken out in advance by classification and weathered to effectively suppress the strength reduction. . As the sieve mesh, 1 mm is preferable because it can be divided into coarse particles that cause a decrease in strength and fine particles that are likely to be weathered. In general, classification is performed by sieving, but classification may be performed by other methods, and fine particles inevitably included in the coarse particle portion may be present.

  As described above, the inventors select coals that cause reduction in coke strength, weather them under appropriate weathering conditions, and blend them after modifying them to weathered coals having appropriate coking properties. Thus, the present inventors have found that the reduction in coke strength can be suppressed and have completed the present invention.

  The penetration distance was measured for 21 types of coal (coal A to U) and one type of caking additive (caking agent V). Table 1 shows the property values of the used coal and the binder. Here, Ro is the maximum vitrinite average reflectance of coal according to JIS M 8816, log MF is the common logarithm of the maximum fluidity (Maximum Fluidity: MF) measured by the Gieseller Plastometer method, volatile content (VM), ash content (Ash) ) Are measured values according to 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 heating element 8 in FIG. 1 was an induction heating coil, and the material of the container 3 was graphite, which is a dielectric. The diameter of the container was 18 mm, the height was 37 mm, and glass beads with a diameter of 2 mm were used as materials having through holes on the upper and lower surfaces. The sample 1 was filled by loading 2.04 g of a coal sample pulverized to a particle size of 2 mm or less and vacuum-dried at room temperature into the container 3 and dropping a weight of 200 g from the top of the coal sample 5 times at a fall distance of 20 mm. (In this state, the sample layer thickness was 10 mm). Next, glass beads having a diameter of 2 mm were placed on the packed layer of Sample 1 so as to have a thickness of 25 mm. A sillimanite disk having a diameter of 17 mm and a thickness of 5 mm is placed on the glass bead packed layer, a quartz rod is placed thereon as the expansion coefficient detecting rod 13, and a weight of 1.3 kg is placed on the quartz rod. placed. As a result, the pressure applied on the sillimanite disk is 50 kPa. Nitrogen gas was used as the inert gas, and the mixture was heated to 550 ° C. at a heating rate of 3 ° C./min. After the heating, cooling was performed in a nitrogen atmosphere, and the mass of beads not fixed to the softened and melted coal was measured from the cooled container. In addition, although said measurement conditions are what the inventors determined as measurement conditions of a preferable penetration distance by the comparison of the measurement result on various conditions, a penetration distance measurement is not restricted to this method.

  In addition, what is necessary is just to arrange | position so that the thickness of a glass bead layer may become layer thickness more than an osmosis | permeation distance. If the melt has penetrated to the top of the glass bead layer during measurement, the glass beads are increased and remeasured. The inventors conducted a test in which the layer thickness of the glass beads was changed, and confirmed that the permeation distance measurement values of the same sample would be the same if there was a glass bead layer thickness greater than or equal to the penetration distance. When measuring a binder with a long penetration distance, a larger container was used and the amount of glass beads filled was also increased.

The penetration distance was the filling height of the fixed bead layer. The relationship between the filling height and the mass of the glass bead packed bed was obtained in advance, and the glass bead filling height could be derived from the mass of the beads to which the softened and melted coal was fixed. The result was equation (8), and the penetration distance was derived from equation (8).
L = (GM) × H (8)
Here, L is the penetration distance [mm], G is the mass of the filled glass beads [g], M is the mass of the beads not fixed to the softened melt [g], and H is the glass beads filled in this experimental apparatus. It represents the height of the packed bed per gram [mm / g].

  FIG. 9 shows the relationship between the measurement results of the osmotic distance and the logarithmic value (log MF) of the Gieseler maximum fluidity (MF). From FIG. 9, the permeation distance measured in this example has a correlation with the maximum fluidity, but there is a difference in the value of the permeation distance even with the same MF. For example, as a result of examining the measurement error of the penetration distance in this device, considering that the standard deviation was 0.6 for the result of three tests under the same conditions, coal A and For Coal C, a significant difference in penetration distance was observed.

  Next, in order to investigate changes in permeation distance, maximum fluidity and coke strength after carbonization due to weathering of coal corresponding to (i) to (d) above, various coals corresponding to (i) to (d) are variously investigated. A coal blend was prepared by blending 10% by weight of what was weathered under the conditions, and the coke strength after dry distillation was measured.

  In the conventional coal blending theory for estimating coke strength, it has been considered that coke strength is mainly determined by the vitrinite average maximum reflectance (Ro) of coal and log MF (for example, see Non-Patent Document 2). .) Therefore, a base blended coal blended with various coals so that the weighted average Ro of the entire blended coal and the weighted average logMF are the average properties of actual operation is prepared (Ro = 1.08, logMF = 2.2). Then, 10% by mass of F coal, which is a coal corresponding to the above (i) to (d), and its weathered coal was added to this blended coal to prepare a blended coal for use in the test.

  Table 2 shows the penetration distance and the maximum fluidity of the coal constituting the base blended coal. In addition, the weighted average property value of the base coal blend is also shown. Here, since the weighted average permeation distance of the base blended coal is 6.5 mm and the permeation distance of the F coal is 19.8 mm, the F coal meets both the above conditions (c) and (d). To do.

  A regression line passing through the origin was determined based on the logarithm of the permeation distance and maximum fluidity of coal with log MF <2.5 constituting the blended coal. The constants a and a ′ in the equations (2) and (4) were determined to be 2.9 which coincided with the obtained slope of the regression line. The constant b in the formula (4) was determined to be 3 from 5 times the value of the standard deviation 0.6 under the measurement conditions of the example of the present invention. Based on these equations, the results of examining the positional relationship between the permeation distance and the maximum fluidity of coal and F coal constituting the blended coal and the ranges (i) and (b) above are shown in FIGS. Each is shown. From FIG. 10, FIG. 11, F charcoal corresponds to any conditions of the range of (A) and (B).

  The weathered coal of F charcoal was produced by leaving it in a heating furnace in an air atmosphere whose temperature was adjusted to 150 ° C. and 200 ° C. for a predetermined time. Moreover, it left still in the heating furnace of the air atmosphere which adjusted the temperature of F charcoal to 200 degreeC for 12 hours, and produced the weathered charcoal (MF = 0) completely weathered. Furthermore, weathered charcoal weathered at room temperature in a drum can for one year was also produced. Table 3 shows the values of weathering conditions, log MF, and permeation distance of F coal and its weathered coal. From weathered F charcoal 1 to weathered F charcoal 4, it can be seen that the log MF and penetration distance values decrease as the weathering time increases, and the rate of decrease tends to decrease with time. When the present inventors weathered coal under various conditions other than the examples, it was confirmed that the log MF and permeation distance were monotonously decreased under any weathering conditions. Therefore, it is possible to arbitrarily reduce the permeation distance by appropriately controlling the weathering conditions.

Table 4 shows the weighted average property values of blended coal prepared by adding 10 mass% of weathered coal described in Table 3 to the base blended coal described in Table 2. The particle size of the blended coal shown in Table 4 was pulverized to be less than 3 mm and 100 mass%, and the water content of the entire blended coal was adjusted to be 8 mass%. 16 kg of this blended charcoal was filled in a dry distillation can so that the bulk density was 750 kg / m ^3, and 10 kg of weight was placed on the can, and after carbonization in an electric furnace with a furnace wall temperature of 1050 ° C., And then cooled with nitrogen to obtain coke. The coke strength of the obtained coke was measured based on the rotational strength test method of JIS K 2151 by measuring the mass ratio of coke with a particle size of 15 mm or more after 15 rpm and 150 revolutions, and the mass ratio with the pre-rotation drum strength DI150 / Calculated as 15. The strength after CO ₂ hot reaction (based on ISO18894 method) and micro strength (MSI + 65) were also measured.

  The measurement results of coke strength are also shown in Table 4. FIG. 12 shows the relationship between the penetration distance of F charcoal and the drum strength. It was confirmed that the strength of the blended coal changes when the penetration distance of the F coal corresponding to the above (i) to (d) is changed variously. Therefore, it was confirmed that the value of the penetration distance measured in the present invention is a factor affecting the strength and cannot be explained by the conventional factor.

  Conventionally, it has been considered that the coke strength at the time of blending also decreases uniformly with the progress of weathering, since the meltability of coal decreases. However, as shown in this example, the blended coal obtained by blending weathered F coal 1, weathered F coal 2, weathered F coal 6 or weathered F coal 8 obtained by weathering F coal corresponding to (i) to (d) above. 2, the blended coal 3, the blended coal 7 or the blended coal 9 has improved coke strength after dry distillation than the blended coal 1 blended with raw coal. Weathered F charcoal 3 and weathered F charcoal 4 blended with weathered F charcoal 4 and blended coal 5 have almost the same coke strength after dry distillation as blended coal 1 blended with raw coal. And the combination coal 6 which mix | blended the weathered F coal 5 completely weathered has the coke strength after dry distillation remarkably falling compared with the combination coal 1 which mix | blended raw coal. That is, when the F charcoal corresponding to the above (i) to (d) is weathered, the coke strength is not reduced uniformly, but the coke strength is once improved and then reduced. . Such a result has been described in the present invention in the weathering phenomenon, as it has been said conventionally, the effect of reducing the coal meltability (log MF) and accordingly reducing the coke strength. It is considered that this is because there are two effects of reducing the permeation distance and improving the coke strength accordingly.

  Here, the results of examining the positional relationship between the permeation distance and the maximum fluidity of weathered F charcoal and the above ranges (A) to (D) are shown in FIGS. The strength improvement effect of the weathered F charcoal 7 corresponding to any range of (e) to (h) is the highest in this example. Moreover, it confirmed that the weathered F charcoal 2 applicable to (g) and (h) and the weathered F charcoal 6 applicable only to (h) also had a strength improvement effect with respect to raw coal. In addition, although weathered F charcoal 8 satisfy | fills all of (e)-(h), since the MF value is near the lower limit shown by (li), although the strength improvement effect became smaller than weathered F charcoal 7, It was recognized that it has a strength improvement effect on charcoal. Therefore, coke strength can be improved by weathering so that the penetration distance and the maximum fluidity of weathered coal are within the ranges defined in the present invention.

  In addition, FIG. 17 shows changes in the penetration distance and maximum fluidity of weathered F charcoal produced by changing the treatment temperature. From FIG. 17, it was confirmed that the weathering at 200 ° C. compared to the case where it was weathered at 150 ° C. had a large decrease in the permeation distance with respect to the decrease in the maximum fluidity, resulting in a desirable property change.

  Even if it is a case where F charcoal corresponding to the above (i)-(d) is used from this example, it is weathered so that a penetration distance and the maximum fluidity may become the range of the above (e)-(li). It was confirmed that the coke strength can be improved by blending after that.

  Investigate the effect of coke strength on weathered coal that weathered only the coarse part of U coal (penetration distance = 46.5 mm, log MF = 4.56) corresponding to the above (i) to (d), which causes a decrease in strength when blended. Therefore, a blended coal in which 10 mass% of U coal or weathered U coal was blended with the base blended coal, and the coke strength after dry distillation was measured.

  Table 5 shows the weighted average property values of the base blended coal. Here, the base blended coal is made of coal with log MF <3.2, the weighted average penetration distance is 9.0 mm, and the penetration distance of U coal is 46.5 mm. ) And (d) both of the conditions are met.

  A regression line passing through the origin was determined based on the logarithm of the permeation distance and maximum fluidity of coal with log MF <2.5 constituting the blended coal. The constants a and a ′ of the equations (2) and (4) were determined to be 3.8, which coincides with the obtained slope of the regression line. The constant b in the formula (4) was determined to be 3 from 5 times the value of the standard deviation 0.6 under the measurement conditions of the example of the present invention. The results of examining the positional relationship between the permeation distance and maximum fluidity of U charcoal based on these formulas and the above ranges (A) and (B) are shown in FIGS. 18 and 19, respectively. From FIG. 18 and FIG. 19, U charcoal corresponds to any condition in the range of (A) and (B).

  Without classifying U charcoal, it left still for 30 minutes in the heating furnace of the air atmosphere adjusted to 200 degreeC, and the weathered U charcoal 1 was produced. In addition, U charcoal is classified by passing through a 1 mm sieve, and only U charcoal having a particle size of 1 mm or more on the sieve is weathered under the same conditions and has a particle size of less than 1 mm that was not subjected to weathering. Weathered U charcoal 2 was prepared by mixing well with U charcoal. Table 6 shows weathering conditions, log MF, and permeation distance values of U coal and its weathered coal. Weathered U charcoal 1 and weathered U charcoal 2 differ in the degree of weathering, and weathered U charcoal 1 that has been weathered in its entirety is reduced in both penetration distance and maximum fluidity compared to weathered U charcoal. confirmed.

  Table 7 shows the weighted average property values of the blended coal prepared by adding 10 mass% of U coal or weathered U coal to the base blended coal described in Table 5. Coke was produced by dry distillation of the blended coal described in Table 7 in the same manner as in Example 1, and the drum strength DI 150/15 was measured based on the rotational strength test method of JIS K 2151.

  The measurement results of drum strength are also shown in Table 7. As this example shows, coke strength of blended coal 11 blended with U coal corresponding to (i) to (d) above is lower than blended coal 10 which is a base blended coal. Moreover, the combination coal 12 and the combination coal 13 which mix | blended the weathered U coal 1 and the weathered U coal 2 have the coke strength after dry distillation improving rather than the combination coal 11 which mix | blended U coal. Further, when the blended coal 12 and the blended coal 13 are compared, the blended coal 13 blended with the weathered coal U coal 2 weathered only with coarse particles has higher coke strength after dry distillation. This is because only the coarse-grained portion of U char that causes strength reduction was weathered, so that the properties of U char were effectively improved without creating fine particles that caused poor adhesion due to preferential weathering. It is guessed that.

  From this example, when coal and caking materials corresponding to the above (i) to (d) are weathered to improve coking properties, only the coarse particles that cause a decrease in strength are weathered. It was confirmed that the effect of suppressing or improving the strength reduction can be effectively obtained.

  By using the permeation distance measured in the present invention, it is possible to determine a brand whose coking property is improved by weathering. Since the weathering reaction can occur spontaneously, it is possible to improve the coking property without incurring extra cost by naturally weathering such brands. Moreover, when improving the coking property of coal by weathering from the above, it is possible to prescribe | regulate an appropriate weathering range. Furthermore, it has also been found that there is an appropriate condition for maximizing the degree of improvement of coking property as a weathering method.

DESCRIPTION OF SYMBOLS 1 Sample 2 Material which has a through-hole in the upper and lower surfaces 3 Container 5 Sleeve 7 Thermometer 8 Heating element 9 Temperature detector 10 Temperature controller 11 Gas inlet 12 Gas outlet 13 Expansion rate detection rod 14 Weight 15 Displacement meter 16 Circular penetration Hole 17 Packing particle 18 Packing cylinder

Claims (11)

A method of producing coke by dry-distilling a blended coal composed of two or more types of coal or a blended coal obtained by blending a binder with two or more types of coal,
Filling a container with each coal and caking additive constituting the blended coal as a sample, placing a material having through holes on the upper and lower surfaces on the sample, heating the sample, and penetrating into the through hole Measure the permeation distance of the sample and the maximum fluidity (log MF) by the Gieseler plastometer method,
Select the coal whose permeation distance and maximum fluidity fall within the control range (A) satisfying the following formula (1) and formula (2),
A part or all of the selected coal is weathered in an oxidizing atmosphere at room temperature or heat treatment, and the coal penetration distance and maximum fluidity after weathering are within the control range (B) where the following formula (5) is satisfied . And blending the weathered coal,
A method for producing metallurgical coke, characterized in that:
logMF ≧ 2.5 (1)
Permeation distance ≧ 1.3 × a × logMF (2)
However, “a” measures at least one permeation distance and log MF of coal and binder in the range of log MF <2.5 among each coal and binder constituting the coal blend, It is a constant in the range of 0.7 to 1.0 times the log MF coefficient when a regression line passing through the origin is created using the measured value .
Penetration distance of coal after the wind of <1.3 × a × maximum fluidity of the coal after weathering (logMF) (5) A method of producing coke by dry-distilling a blended coal composed of two or more types of coal or a blended coal obtained by blending a binder with two or more types of coal,
Filling a container with each coal and caking additive constituting the blended coal as a sample, placing a material having through holes on the upper and lower surfaces on the sample, heating the sample, and penetrating into the through hole Measure the permeation distance of the sample and the maximum fluidity (log MF) by the Gieseler plastometer method,
Select the coal whose permeation distance and maximum fluidity fall within the control range (A) satisfying the following formula (3) and formula (4),
Some or all of the selected coal is weathered in an oxidizing atmosphere at room temperature or heat treatment, and the coal penetration distance and maximum fluidity after weathering are within the control range (B) where the following equation (6) is satisfied . And blending the weathered coal,
A method for producing metallurgical coke, characterized in that:
logMF ≧ 2.5 (3)
Permeation distance ≧ a ′ × log MF + b (4)
However, "a '" measures the penetration distance and log MF of at least one kind of coal and binder in the range of log MF <2.5 among the coal and binder that constitute the blended coal, It is a constant in the 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.
“B” is a constant that is not less than the average value of the standard deviation when measuring one or more types of the same sample selected from the brands used to create the regression line, and not more than 5 times the average value. There is .
Penetration distance of coal after the wind of <a '× maximum fluidity of the coal after weathering (logMF) + b (6) A method of producing coke by dry-distilling a blended coal composed of two or more types of coal or a blended coal obtained by blending a binder with two or more types of coal,
Filling a container with each coal and caking additive constituting the blended coal as a sample, placing a material having through holes on the upper and lower surfaces on the sample, heating the sample, and penetrating into the through hole Measure the permeation distance of the sample and the maximum fluidity (log MF) by the Gieseler plastometer method,
Select the coal whose permeation distance and maximum fluidity fall within the management range (A) required by the following (a) to (c),
Coal part or all of the selected coal, an oxidizing atmosphere, weathered by cold or heat treatment, penetration distance coal after weathering, to be within the management scope of the following (B), described above weathered Blending,
A method for producing metallurgical coke, characterized in that:
(A) Predetermining the coal or caking additive contained in the coal blend used for coke production, and the blending ratio of the coal or caking additive,
(B) Measure the penetration distance and log MF of the coal or binder;
(C) The control range (A) is a range that is at least twice the weighted average penetration distance calculated from the penetration distance and blending ratio of coal or binder with a log MF less than 3.2 contained in the blended coal. To decide .
Management range (B) is in the range of penetration distance is less than 2 times the weighted average permeation distance calculated above (c). A method of producing coke by dry-distilling a blended coal composed of two or more types of coal or a blended coal obtained by blending a binder with two or more types of coal,
Filling a container with each coal and caking additive constituting the blended coal as a sample, placing a material having through holes on the upper and lower surfaces on the sample, heating the sample, and penetrating into the through hole Measure the permeation distance of the sample and the maximum fluidity (log MF) by the Gieseler plastometer method,
Select the coal whose permeation distance and maximum fluidity fall within the management range (A) determined by (d) and (e) below,
Coal part or all of the selected coal, an oxidizing atmosphere, weathered by cold or heat treatment, penetration distance coal after weathering, to be within the management scope of the following (B), described above weathered Blending,
A method for producing metallurgical coke, characterized in that:
(D) Coal or caking material sample is pulverized so that the particle size is 2 mm or less is 100 mass%, and the pulverized sample is filled into a container so as to have a packing density of 0.8 g / cm ³ and a layer thickness of 10 mm. A glass bead having a diameter of 2 mm is arranged on the sample with a layer thickness equal to or greater than the permeation distance, and a heating rate is 3 ° C./min while applying a load from the top of the glass bead to a pressure of 50 kPa. In the measurement conditions when heated in an inert gas atmosphere from room temperature to 550 ° C., the penetration distance of the management range (A) is 15 mm or more, and
(E) The log MF of the management range (A) is 2.5 or more .
Management range (B) is a coal after weathering and coal samples were pulverized the coal sample as the particle size 2mm or less is 100 mass%, the ground sample in packing density 0.8 g / cm ^3, the layer Fill the container so that the thickness is 10 mm and use it as a sample. Place a glass bead with a diameter of 2 mm on the sample with a layer thickness equal to or greater than the penetration distance, and apply a load from the top of the glass bead to a pressure of 50 kPa. However, it is the range of the permeation distance that is less than 15 mm as measured when heated in an inert gas atmosphere from room temperature to 550 ° C. at a rate of temperature rise of 3 ° C./min. Maximum fluidity degree l ogMF ≧ 2.5 coal after weathering, and penetration distance of the coal after weathering which is characterized in that is weathered to be within the scope of the management range (B), claims 1 The manufacturing method of the metallurgical coke of any one of Claim 4. The oxidizing atmosphere for performing the weathering is a gas atmosphere containing one or more components of O ₂ , CO ₂ , and H ₂ O, according to any one of claims 1 to 5. The manufacturing method of the metallurgical coke as described.   The method for producing metallurgical coke according to claim 6, wherein the oxidizing atmosphere at the time of the weathering is an air atmosphere.   The metallurgical coke according to any one of claims 1 to 7, wherein the heat treatment at the time of the weathering is a treatment temperature of 100 ° C to 300 ° C and a treatment time of 1 to 120 minutes. Manufacturing method.   The method for producing metallurgical coke according to claim 8, wherein the heat treatment at the time of the weathering is a treatment temperature of 180 ° C. to 220 ° C. and a treatment time of 1 to 30 minutes.   When performing the weathering, part or all of the coal and caking additive used for coke production are classified in advance, and only particles having a predetermined mesh size or more are weathered. 10. The method for producing metallurgical coke according to any one of 9 above.   The metallurgy according to claim 10, characterized in that, when the weathering is performed, a predetermined sieve mesh for classifying coal and caking additive used for coke production is selected from a range of 1 mm to 6 mm. Coke production method.