JP2014214243A - Selection method of caking filler, and manufacturing method of high strength coke using the filler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for properly selecting a caking filler suitable for each type of coal in manufacturing of high strength coke; and a manufacturing method of a high strength coke using the filler.SOLUTION: By a testing method of swelling properties in accordance with JIS M8801, the maximum shrinkage temperature Tand the maximum expansion temperature Tof a caking coal are obtained. From premeasured mass decrease curves of a plurality of caking filler, the mass decrease rate of each caking filler in the temperature range of T-Tis obtained as a gas utilization rate. The selection method of caking filler includes selecting a caking filler having a gas utilization rate equal to or higher than the volatilization rate of caking coal in the temperature range of T-T. The manufacturing method of a high strength coke includes obtaining coke by adding the caking filler thus selected to caking coal.

Description

  The present invention relates to a method for selecting a caking filler to be added to caking coal in producing high-strength coke, and a method for producing high-strength coke using this selection method.

  Coke used as a reducing material for iron ore in a blast furnace to obtain pig iron is produced by dry distillation in a coke oven using raw coal or blended coal blended with multiple types of coal, but aeration in the blast furnace In order to obtain a high-strength coke that can secure sufficient properties, it is necessary to contain a large amount of strong caking coal having excellent caking properties and carbonization characteristics. However, since strong caking coal is expensive and has limited resources, a technique of adding caking filler to raw coal and charging it into a coke oven is widely adopted.

  With regard to the addition of such a caking filler, for example, high strength molding is achieved by adding and mixing the raw material charcoal with a mixture of aromatic bituminous material (ASP) and coal tar dissolved together. A method for producing charcoal has been proposed (see Patent Document 1). In addition, together with a pore-generating agent such as plastic that decomposes thermally at a temperature close to the solidification temperature of coal, a binder such as coal-based or petroleum-based pitch is added to the blended coal, and the porosity is high and A method for obtaining coke having a strength of a certain level or more has been proposed (see Patent Document 2). Furthermore, when the coal is carbonized in a coke oven, by adding waste plastics controlled to a predetermined particle size upper limit or less, the gas generated by thermal decomposition is included in the softened molten layer of coal, and the softened molten layer A method has been proposed in which cohesion between softened and melted coals is strengthened by an internal gas pressure to obtain coke having high strength (see Patent Document 3).

  However, since the properties of coal differ depending on the production area, brand, etc., for example, even though a caking filler suitable for a certain raw coal can be found by the above method, it is suitable for each coal type. It does not lead to the selection of caking filler.

  On the other hand, the components that make up the caking filler are divided into components that are soluble in hexane (HS components), components that are insoluble in hexane and soluble in toluene (HITS components), and components that are insoluble in toluene (TI components). Thus, each action in the caking filler can be found, and a caking filler having an appropriate component composition can be selected in accordance with the properties (volatile content, caking nature, etc.) of the raw coal to be added. Such a method has been proposed (see Patent Document 4). Specifically, the HS component (light component) constituting the caking filler is gasified during dry distillation, promotes bubble growth and coalescence in the softened and melted coal, and increases the pore size to an appropriate size. The HITS component (intermediate component) reduces the viscosity of coal that has been softened and melted during the dry distillation process, and makes the bubble shape round (pore rounding effect). The TI component (heavy component) is mostly a residual, but the coking coal is divided into four categories according to the total expansion rate, assuming that it has an action to thicken the coke wall (wall thickness increasing action), The range of the addition ratio of the three components in the caking filler is determined according to each category.

  Alternatively, a method has been proposed in which the temperature at which the porosity of the raw coal is minimized and the temperature at which the porosity is maximized are selected and the caking filler is selected from a combination that can effectively use the gas from the caking filler in this temperature range. (See Patent Document 5). Specifically, the mass reduction curves of plural types of caking filler materials are measured in advance, and the mass of each caking filler material in the temperature range between the temperature at which the porosity of the raw coal becomes the minimum and the maximum temperature. The reduction rate is obtained as a gas availability rate, and the gas availability rate exceeds the volatilization rate of the raw coal.

Japanese Patent Publication No.52-3402 Japanese Patent Laid-Open No. 11-236573 Japanese Patent No. 423213 Japanese Patent Laid-Open No. 2007-9030 JP2013-28800A

  As described above, various caking fillers added to coking coal have been known and used so far, but the nature of coal itself varies depending on the production area and brand, There seems to be an optimal combination of caking fillers for each type of coal. Therefore, as described in Patent Documents 4 and 5, selecting a caking filler suitable for raw coal is extremely important in producing high-strength coke. Especially, according to the method described in patent document 5, the caking filler which contributes to the improvement of coke strength according to raw coal can be selected easily.

  However, when the inventors proceeded with further studies, when selecting a caking filler to be added to caking coal, the temperature range from the state where the coal began to expand to the completion of resolidification (that is, It was found that a wide range of caking fillers can be targeted by focusing on the temperature range in which the coal is melted, thereby enabling more accurate selection.

  Accordingly, an object of the present invention is to provide a method capable of accurately selecting a caking filler suitable for each type of caking coal in the production of high-strength coke. Another object of the present invention is to provide a method capable of effectively producing high-strength coke using this method.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the gas generated from the caking filler contributes to the expansion of the coal, in the process of coal softening and expanding and resolidifying. The present inventors have newly found that it is necessary that the gas derived from the caking filler material can be sufficiently captured, and that the coal itself has a certain amount of molten component like caking coal. Then, by finding the maximum shrinkage temperature and maximum expansion temperature of the caking coal, supplementing the volatile content of the caking coal in this temperature range, and further selecting a caking filler that can exceed the volatile content. The present invention has been completed since the caking filler that contributes to the improvement of coke strength can be selected accurately.
That is, the gist of the present invention is as follows.

(1) A method of selecting a caking filler to be added to caking coal in producing high-strength coke, and the maximum shrinkage temperature T ₁ and the max expansion of caking coal according to the expansibility test method described in JIS M8801. The temperature T ₂ is obtained, and the mass reduction rate of each caking filler in the temperature range of T ₁ -T ₂ is determined from the mass reduction curves of the plurality of caking fillers measured in advance as the gas availability rate. determined, the gas available rates, selection methods caking filling material and selects the caking filling material becomes more volatile rate of coking coal in the T ₁ -T ₂ temperature range.
(2) volatilization rate of coking coal in the T ₁ -T ₂ temperature range, a mass reduction rate of the caking coal in T ₁ -T ₂ temperature range in weight loss curve of caking coal with respect to temperature (1 )).
(3) The caking filler is up to 900 ° C in nitrogen at 3 ° C / min. In the mass reduction rate curve obtained by first-order differentiation of the mass reduction curve when the temperature is raised with time, the temperature at which the mass reduction rate is maximized is selected from caking fillers having a temperature of 400 ° C. or higher (1) or The method for selecting the caking filler according to (2).
(4) Select a caking filler material having the highest gas availability rate from those where the caustic rate of the caking filler in the T ₁ -T ₂ temperature range is equal to or higher than the volatilization rate of caking coal (1 ) To (3). The method for selecting a caking filler according to any one of (3).

(5) A method of producing a high-strength coke by adding a caking filler to caking coal, and producing high-strength coke, wherein the maximum shrinkage temperature T _{1 of} caking coal is determined by an expansibility test method described in JIS M8801. The maximum expansion temperature T ₂ is obtained, and the mass reduction rate of each caking filler in the temperature range of T ₁ -T ₂ can be used from the mass reduction curves of plural kinds of caking fillers measured in advance. The high-strength coke is characterized by selecting and adding a caking filler that is obtained as a rate and the gas availability rate is equal to or higher than the volatilization rate of caking coal in the T ₁ -T ₂ temperature range. Method.
(6) Volatile ratio of caking coal in the T ₁ -T ₂ temperature range, a mass reduction rate of the caking coal in T ₁ -T ₂ temperature range in weight loss curve of caking coal with respect to temperature (5 The manufacturing method of the high intensity | strength coke as described in).
(7) The caking filler is up to 900 ° C in nitrogen at 3 ° C / min. In the mass reduction rate curve obtained by first-order differentiation of the mass reduction curve when the temperature is raised with time, the temperature at which the mass reduction rate is maximized is selected from among caking fillers having a temperature of 400 ° C. or more (added) ( The method for producing high-strength coke according to 5) or (6).
(8) Among the materials in which the gas availability rate of the caking filler in the T ₁ -T ₂ temperature range is equal to or higher than the volatilization rate of caking coal, the caking filler material having the highest gas availability rate is selected and added. The method for producing high-strength coke according to any one of (5) to (7).

  According to the present invention, in producing high-strength coke, a caking filler that contributes to the improvement of coke strength can be accurately selected for each coal type of caking coal. In addition, if this method is used, an effective caking filler can be selected and added for each type of caking coal, so that it is possible to effectively produce high-strength coke. .

FIG. 1 is a graph showing the temperature change of the expansion coefficient of caking coal obtained by the dilatometer method. FIG. 2 is a graph showing the relationship between the gas utilization index and maximum expansion rate improvement allowance ΔMD in caking coal (A coal). FIG. 3 is a graph showing the relationship between the gas utilization index and the maximum expansion rate improvement allowance ΔMD in caking coal (B charcoal). FIG. 4 is a graph showing the relationship between the gas utilization index and maximum expansion rate improvement allowance ΔMD in caking coal (C charcoal). FIG. 5 is a graph showing the relationship between the gas utilization index and the maximum expansion rate improvement allowance ΔMD in non-slightly caking coal (D charcoal). FIG. 6 is a graph showing the relationship between the gas utilization index and the maximum expansion rate improvement allowance ΔMD in non-slightly caking coal (E charcoal). FIG. 7 is a graph collectively showing a weight reduction curve of the caking filler (additives 1 to 4) used in the experiment and a T ₁ -T ₂ temperature range of coal (A coal to E coal). FIG. 8 is a graph showing the effect of the total expansion rate on the surface fracture strength DI ¹⁵⁰ ₆ of coke.

Hereinafter, the present invention will be described in detail.
In the present invention, when selecting a caking filler that contributes to the improvement of coke strength, the coal to be blended is caking coal, and the expansion of the caking coal can be promoted to effectively improve the coke strength. Try to find caking filler.

Generally, coal begins to soften at a temperature of about 400 ° C. and then expands and resolidifies at a temperature of about 500 ° C. As can be seen from the experimental results described later, the coal melt at that time is a caking filler. In order to sufficiently capture the gas from the source and promote the expansion of the coal so that the coal particles can be suitably adhered, the coal itself, like caking coal, has some molten component. It has been found advantageous to have. Therefore, in the present invention, the maximum shrinkage temperature T ₁ and the maximum expansion temperature T _{2 of the} caking coal are obtained by the expansibility test method (dilatometer method) described in JIS M8801, and this T ₁ -T ₂ A caking filler that can generate a large amount of gas in the temperature range and compensate for the volatile content of caking coal is selected.

In the present invention, a mass reduction curve with respect to temperature is measured for a plurality of types of caking fillers to be selected, and the mass reduction rate of each caking filler in the T ₁ -T ₂ temperature range can be used as a gas. Try to find it as a rate. By selecting a caking filler that has a gas availability rate that is equal to or higher than the volatility of caking coal in the T ₁ -T ₂ temperature range, preferably a caking filler that exceeds the volatility of caking coal. Thus, the coke strength can be effectively improved.

Here, the expansibility test method described in JIS M8801 is a method in which a finely pulverized sample (coal) is pressure-molded into a prescribed rod shape, inserted into a prescribed thin tube, a piston is placed on it, and a prescribed ascension is obtained. Heating at a temperature rate, measuring the displacement of the piston up and down, and expressing the softening and melting characteristics of the sample as a fraction (%) of the initial length of the rod-shaped sample. The temperature when it reaches is called the maximum contraction temperature (T ₁ ), and the temperature that reaches the highest position for the first time after the piston reaches the lowest position is called the maximum expansion temperature (T ₂ ). FIG. 1 shows a state of temperature and displacement according to an expansibility test method for a caking coal (B coal described later), and shows a maximum shrinkage temperature T ₁ and a maximum expansion temperature T ₂ . In FIG. 1, the displacement of the piston is expressed as an expansion rate (%). This expansion rate is a fraction (%) of the displacement from the zero point to the highest position of the piston with respect to the initial length of the rod-shaped sample. ).

The present inventors expanded the expandability of JIS M8801 when the caking filler of additives 1 to 4 shown in Table 2 was added to the five types of coal shown in Table 1 (A charcoal to E charcoal). An experiment was conducted to investigate the allowance for improving the maximum expansion rate (ΔMD) by the test method. Here, the maximum expansion rate improvement allowance (ΔMD) is the same as the maximum expansion rate MD when each coal is individually measured by the dilatometer method and an additive is added to each coal at a predetermined ratio. It represents the difference (ΔMD = MD′−MD) from the maximum expansion coefficient MD ′ when measured. Further, in this experiment, the T ₁ -T ₂ temperature range of five coal, the mass decrease rate of the respective caking filling material to previously obtain a gas available rate, gas utilization index obtained from the following equation [ The relationship between [−] and the maximum expansion rate improvement allowance (ΔMD) [%] was determined. The results are as shown in FIGS. In addition, about the ratio of the additive added to each coal, additive 1 is 3 mass%, additives 2 and 3 are 1 mass%, 2 mass%, and 3 mass%, respectively, and additive 4 is carbon C. 1 wt.% Was added only to the amount (both added amounts are internal numbers).
Gas utilization index [−] = gas availability rate [mass%] × addition rate [mass%] / 100

  Among the coals used in the above experiments, AC charcoal is caking coal, and DE charcoal is non-caking coal. Regarding the classification of caking coal and non-caking caking coal, coal with a resolidification temperature of less than 470 ° C in the key celler plastometer method specified in JIS M8001 is made non-caking caking coal, and the resolidification temperature is 470 ° C. The above coal was used as caking coal. As apparent from the graphs shown in FIGS. 2 to 6, in the case of caking coal (A to C charcoal), the maximum expansion rate improvement (ΔMD) increases linearly as the gas utilization index increases. On the other hand, in the case of non-slightly caking coal (D to E charcoal), even if the gas utilization index increases, the increase in the maximum expansion rate improvement margin (ΔMD) is small.

Table 3 shows the results of measuring the amount of molten components of A to E charcoal using high temperature NMR (NMR: Nuclear Magnetic Resonance). ^In the spectrum measurement of coal by ¹ H-NMR, it is known that there are a mobile component with a long relaxation time and an immobile component with a short relaxation time (reference: Nippon Steel Technology Shin No. 384, p. 48). -52 (2006), Journal of the Japan Institute of Energy Vol.83, pp.889-894 (2004), JP 2002-195966 A). Therefore, Table 3 shows the values (%) of A to E charcoal using the mobile component measured by the high temperature NMR as a molten component.

  Specifically, in the measurement of high temperature NMR, the pulse width of 90 degrees hydrogen was 8 μsec, the echo time was 50 μsec to 3 msec, the repetition time was 5 msec to 1 sec, and the number of integrations was 512 times. The data size was set to 512 points in the X direction, 512 points in the Y direction, and 1 to 512 points in the Z direction. At that time, the sample was placed at 3 ° C / min. While raising the temperature, the heating temperature range is set to 30 to 550 ° C., and magnetic field gradients of 89 gauss / cm, 96 gauss / cm, and 107 gauss / cm are applied in a short time to the three axes of X, Y, and Z, respectively. Measurements were made. The abundance of mobile (melting component) means the amount of the component whose transverse relaxation time is 100 microseconds or more in the softening melting temperature region, and corresponds to the component ratio in the coal melted in the softening melting temperature region. To do. Note that multiple pulses and lateral relaxation time are also described in Japanese Patent Application Laid-Open No. 11-326248.

  When combined with the experiments related to FIGS. 2 to 6, the increase in the maximum expansion rate improvement (ΔMD) is larger than that of the AC charcoal in which the maximum expansion rate improvement (ΔMD) increases linearly with the gas utilization index. It can be seen that the amount of molten component is small in the D and E coals, which were slight. That is, in order for the gas generated from the additive (caking filler) to contribute to the expansion of the coal, the coal derived from the additive is melted during the process of coal softening and then expanding and resolidifying. It is considered important that an object can be sufficiently trapped. From these experimental results, the amount of the molten component of the coal capable of trapping the additive-derived gas is required to be about 40%, and the coal should contain a certain amount or more, preferably 40% or more.

Here, it is known that the surface fracture strength DI ¹⁵⁰ ₆ of coke is higher as the expansibility of coal is higher (Reference: Shin-Nippon Technical New No. 384, p.43-47 ( 2006)). FIG. 8 is a graph showing the effect of total expansion on DI ¹⁵⁰ ₆ quoted from this reference. Based on this relationship, if the maximum expansion rate improvement allowance (ΔMD) can be increased effectively, it will contribute to the improvement of coke strength, such as a caking filler with a high gas utilization index and AC charcoal. It is considered that high-strength coke can be efficiently produced by selecting a combination with caking coal. At that time, preferably, the caking filler material having the highest gas availability rate is selected from those having a caustic coal volatility rate higher than the caking rate of caking coal in the T ₁ -T ₂ temperature range. By doing so, the optimal combination of caking coal and caking filler can be found.

As for the caking filler, known petroleum-based caking fillers and coal-caking caking fillers are known as known ones used so far, and waste plastics can also be used. . In the present invention, a material suitable for the caking coal to be blended may be selected from these known caking fillers, and among them, a large amount in the T ₁ -T ₂ temperature range described above. As a caking filler that can effectively improve the coke strength by generating a high temperature gas, it is preferably 3 ° C./min. In the mass reduction rate curve obtained by first-order differentiation of the mass reduction curve when the temperature is raised with time, the temperature at which the mass reduction rate is maximized is 400 ° C. or higher (that is, the temperature at which coal is generally melted) It is good that it is. Specific examples of the caking filler having such properties include petroleum caking fillers (petroleum pitches such as yurika pitch and solvent-desulfurized asphalt) and plastics (polyethylene, etc.). In addition, all of the additives 1 to 4 shown in Table 2 above are petroleum-based caking fillers.

Further, the volatilization rate of the caking coal in the T ₁ -T ₂ temperature range is generally about 1 to 3 wt%. The volatiles of the caking coal is considered to be almost the same components as the volatiles in T ₁ -T ₂ temperature range, such as petroleum coking prosthetic material. Therefore, the mass reduction rate of the caking filler in the T ₁ -T ₂ temperature range obtained from the mass reduction curve is defined as the gas utilization rate, and this gas utilization rate is the volatilization rate of caking coal in the T ₁ -T ₂ temperature range. By selecting the above, it is possible to reliably find a caking filler that contributes to the improvement of coke strength for the caking coal. Here, from the viewpoint of more accurately determining the volatilization rate of the caking coal in the T ₁ -T ₂ temperature range, preferably, the mass reduction curve of the caking coal to be measured is measured in advance. The mass reduction rate of caking coal in the T ₁ -T ₂ temperature range is preferably the volatilization rate.

Here, in FIG. 7, the mass reduction curve of the caking filler of additives 1 to 4 shown in Table 2 above and the T _{1 to} T ₂ temperature range of A to E charcoal shown in Table 1 are shown. It is shown together. Table 4 shows the details of the melting temperature range (T ₁ -T ₂ temperature range) of these A to E coals and the volatile content (volatility) of each coal in that temperature range, and the melting temperature range for each coal. Details of the volatile content (gas availability) of additives 1 to 4 are shown.

As described above, in the present invention, the maximum shrinkage temperature T ₁ and the maximum expansion temperature T ₂ of the coal are obtained by the expansibility test method described in JIS M8801, and the volatilization of coal in this T ₁ -T ₂ temperature range. A caking filler is selected that generates an amount of gas that can compensate for or exceed the volatile content. On the other hand, in the conventional method according to Patent Document 5, the temperature at which the porosity of coal at a predetermined temperature change (from 350 ° C. to 550 ° C.) is minimized (here, t ₁ ) and the maximum temperature. (Here, t ₂ ) is obtained, and a caking filler that generates an amount of gas that supplements the volatile content of coal in the temperature range of t ₁ -t ₂ is selected. That is, the invention according to the present invention and the invention according to Patent Document 5 are different in that the index to be noticed in the process of coal softening and expanding and resolidifying is different.

That is, in the invention according to Patent Document 5, the temperature range where the porosity is minimum-maximum is obtained, and the temperature range from the state where the coal starts to expand to the start of resolidification (that is, the coal is sufficiently melted). Focus on the temperature range. On the other hand, in the present invention, in the case of caking coal, even after the start of resolidification of the coal, if a part of the coal is melted, the gas derived from caking filler can be captured, The T ₁ -T ₂ temperature range is obtained from the maximum contraction temperature T ₁ and the maximum expansion temperature T _{2 by the} dilatometer method.

Further, in Patent Document 5, the maximum shrinkage temperature T ₁ and the maximum expansion temperature T ₂ of coal are obtained by the dilatometer method, and the pores of coal are obtained by using these intermediate temperatures T ₃ = (T ₁ + T ₂ ) / 2. It is assumed that the temperature t ₂ at which the rate is maximum can be substituted (see paragraphs 0054 to 0056 of Patent Document 5). That is, as shown in FIG. 1, the intermediate temperature T ₃ is shown in FIG. 1, according to Patent Document 5, the temperature from the maximum shrinkage temperature T _{1 of} coal determined by the dilatometer method to the intermediate temperature T _3. The region can be regarded as the t ₁ -t ₂ temperature region where the porosity of coal is minimum-maximum. This is because, as described above, Patent Document 5 focuses on a temperature range in which coal is sufficiently melted. In the present invention, when caking coal is used, attention is paid to the temperature range from the state where the coal begins to expand to the end of resolidification, and the temperature range from T ₃ to T ₂ is also added. It will be. That is, in the present invention, by specifying the combination with caking coal, compared with the method described in Patent Document 5, the selection range of an appropriate caking filler to be combined is widened, thereby further optimizing. A caking filler can be selected.

For example, when the mass decrease curve of the additive 4 shown in FIG. 7 is seen, it can be seen that the thermal decomposition is rapidly performed from 400 ° C. to 500 ° C. In the case of such an additive 4, for example, when the blending target is C charcoal, if the temperature range of interest is the T ₁ -T ₃ temperature range, the additive 4 is not selected as the optimum caking filler, If the temperature range to be performed is the T ₁ -T ₂ temperature range, the additive 4 is selected as an optimum caking filler.

That is, when the blending target is C charcoal, the volatile matter in the T ₁ -T ₂ temperature range of C charcoal when 1 mass% of additive 2 is added and when 1 mass% of additive 4 is added. (Gas availability) is 25.0% for additive 2 and 46.3% for additive 4, and using additive 4 is considered to contribute more effectively to the expansion of coal. .
On the other hand, if the volatile content in the T ₁ -T ₃ temperature range is compared, the additive 2 is 14.5% and the additive 4 is 9.6%, and the additive 2 is T ₁ -T _3. This results in a large amount of volatile matter (availability of gas) in the temperature range. In practice, however, as shown in FIG. 4, additive 4 can increase the maximum expansion rate improvement (ΔMD), and additive 4 is more suitable as a caking filler for C charcoal. It can be said that.

Therefore, for example, when the blending target is C charcoal, the additive 4 is selected by setting the temperature range of interest to be the T ₁ -T ₂ temperature range, and the selection range of an appropriate caking filler is selected. As the spread increases, a more optimal caking filler can be selected.
Regarding additives 1 to 3, when determining the optimum caking filler with the largest amount of volatile matter, there is a difference between the case of T ₁ -T ₂ temperature range and the case of T ₁ -T ₃ temperature range. Confirm that there is no.

When producing high-strength coke in the present invention, using the above-described method for selecting a caking filler, caking having a gas availability rate equal to or higher than the volatilization rate of caking coal in the T ₁ -T ₂ temperature range. A filler is selected, and preferably, the caustic filling material having the highest gas availability rate among the caking coal volatilization rate is higher than the caking rate of caking coal in the T ₁ -T ₂ temperature range. A material may be selected and added to caking coal for dry distillation.

  Here, although the addition amount of the selected caking filler is not particularly limited, it is generally about 0.1% by mass to 10% by mass. In addition, when producing high-strength coke, a known method can be used as a method for adding a caking filler, for example, drying in a fluidized bed before charging caking coal into a coke oven. -Classification may be performed, and there are no particular restrictions on dry distillation conditions. However, when caking coal is dried and classified in a fluidized bed, it is preferable to add caking filler to the dried coal. Note that at least one of the selected caking fillers may be added to the raw coal and dry-distilled, but two or more caking fillers may be blended. Moreover, when using as a raw material a blended coal containing a plurality of caking coals, it is possible to select caking fillers using the selection method of the present invention for each caking coal and add each of them. desirable.

In the present invention, after adding a coal-based caking filler to caking coal in advance, the maximum shrinkage temperature T ₁ and the maximum expansion temperature T ₂ are obtained by the dilatometer method, and this T ₁ − From the relationship between the gas utilization rate of the caking filler in the T ₂ temperature range and the volatilization rate of caking coal with the coal-based caking filler added, the caking filler is selected as described above, You may make it add. That is, when a coal-based caking filler is added to caking coal in advance, there is an effect that the T ₁ -T ₂ temperature range is expanded as compared with the case where this is not added. Therefore, the gas generated from the selected caking filler can be used more effectively by using caking coal blended with a coal-based caking filler.

  The present invention will be described more specifically based on examples, but the present invention is not limited to these contents.

  Using the A to E charcoal having the properties shown in Table 1 and the additives (caking fillers) 1 to 4 having the properties shown in Table 2, the caking supplement of the present invention is as follows. An experiment related to a method of selecting a material was performed.

First, the softening and melting characteristics of each coal were examined for A to E charcoal according to the expansibility test method described in JIS M8801. That is, a finely pulverized sample (coal) is pressure-molded into a specified rod shape, inserted into a specified thin tube, a piston is placed on it, and then heated at a specified rate of temperature rise and down. The softening start temperature, the maximum shrinkage temperature T ₁ , the maximum expansion temperature T ₂ , the maximum shrinkage rate, and the maximum expansion rate of each coal were determined. Further, 20 mg of coal was heated to 900 ° C. at 3 ° C./min under a nitrogen atmosphere, and the change with time in mass was measured with a thermobalance to obtain a mass reduction curve of each coal. Similarly, for Additives 1 to 4, 20 mg of the additive was heated to 900 ° C. at 3 ° C./min under a nitrogen atmosphere, and the mass change over time was measured with a thermobalance to obtain respective mass reduction curves. . FIG. 7 collectively shows the T ₁ -T ₂ temperature range (melting temperature range) of A to E charcoal obtained above and the mass reduction curves of the additives 1 to 4.

Based on these, the T ₁ -T ₂ temperature range (melting temperature range) of A to E coals, the mass reduction rate (volatile matter) in the T ₁ -T ₂ temperature range of each coal determined from the mass reduction curve, and The mass reduction rate (volatile content) in the T ₁ -T ₂ temperature range of the additives 1 to 4 obtained from the mass reduction curve was obtained and summarized in Table 4 above.

Here, regarding the combination of each coal and additive shown in Experiment Nos. 1 to 16, the mass reduction rate (volatile content) of each caking filler in the temperature range of T ₁ -T ₂ is regarded as the gas availability rate. For example, the additives 1 to 4 exceed the volatility (volatile content) of coal in the T ₁ -T ₂ temperature range in any combination of A to E charcoal. However, as shown in FIGS. 2 to 6, in the case of AC coal, which is caking coal, the maximum expansion coefficient improvement margin (ΔMD) increases linearly as the gas utilization index increases. In the case of D to E coal, which is non-slightly caking coal, even if the gas utilization index increases, the increase in the maximum expansion rate improvement margin (ΔMD) is slight. It is considered that the effect that the gas generated from the caking filler contributes to the expansion of coal is small. On the other hand, for example, in Coal C, the additive 4 has the highest gas availability rate. Actually, in the case of additive 2 when compared with the case where the additive amount is 1% by mass (inner number), ΔMD = 8.9%, Additive 3 for ΔMD = 6.1%, Additive 4 for ΔMD = 20.2%, and Additive 4 has the most contribution to C charcoal expansion Is considered high.

In addition, blended coal was formed from the above using A coal, B coal, and E coal, and additives 2 and 3 were used as caking filler, and coke was test-produced as follows.
First, A charcoal, B charcoal, and E charcoal were each pulverized so that the particle size of 3 mm or less was 85% by mass, and as shown in Table 5, the blending ratio (mass%) was 25% of A charcoal, It mix | blended so that it might become 25% of B charcoal and 50% of E charcoal. When additive 2 and 3 are not added at all to such a blended coal (level 1), only additive 2 is added in a mass ratio of 3% (internal number) (level 2), only additive 3 is mass When 3% (inner number) was added in a ratio (level 3), each was charged into an experimental dry distillation apparatus so that the bulk density was 0.85 g / cm ³ (dry state). Each of these was heated at a furnace temperature of 1250 ° C. for 18.5 hours to produce test coke, and coke strengths DI ¹⁵⁰ ₁₅ (−) and DI ¹⁵⁰ ₆ were measured.

Note that DI ¹⁵⁰ ₆ and DI ¹⁵⁰ ₁₅ have the following relationship.
DI ¹⁵⁰ ₁₅ = DI ¹⁵⁰ ₆ -DI ¹⁵⁰ _6-15
As shown in FIG. 8, the DI ¹⁵⁰ ₆ is affected by the adhesion between coal particles due to the expansion of the coal, and the DI ¹⁵⁰ _6-15 is affected by cracks due to shrinkage. Since the expandability of coal changes due to the addition of the caking filler, the change in strength due to the addition of the caking filler mainly originates from the change in DI ¹⁵⁰ ₆ and DI ¹⁵⁰ _6-15 hardly changes. As a result, DI ¹⁵⁰ ₁₅ is improved as a result.

The results are as shown in Table 5. Here, ΔDI ¹⁵⁰ ₆ and ΔDI ¹⁵⁰ ₁₅ indicate the increments from coke strength DI ¹⁵⁰ ₆ and DI ¹⁵⁰ ₁₅ when manufactured without any additives, respectively. In addition, the gas utilization index is a value obtained from the previous equation. Here, the gas utilization index of simple coal is calculated by weighted average according to the blending ratio of coals A and B, which are caking coals. (The gas utilization index for non-slightly caking coal E is zero). From these results, it can be seen that the coke strength improvement effect ΔDI ¹⁵⁰ ₆ and ΔDI ¹⁵⁰ ₁₅ are larger in the case of level 2 where the gas utilization index is high, and high strength coke can be produced efficiently.

Claims (8)

This is a method for selecting a caking filler to be added to caking coal in the production of high-strength coke. The caking coal has a maximum shrinkage temperature T ₁ and a maximum expansion temperature T _{2 according} to the expansibility test method described in JIS M8801. In addition, from the mass reduction curves of a plurality of types of caking fillers measured in advance, the mass reduction rate of each caking filler in the temperature range of T ₁ -T ₂ is obtained as a gas availability rate, A method for selecting a caking filler, wherein the caustic filling material is selected such that the gas availability rate is equal to or higher than the volatilization rate of caking coal in the T ₁ -T ₂ temperature range. Volatilization rate of coking coal in the T ₁ -T ₂ temperature range, according to claim 1 wherein the mass reduction rate caking coal in T ₁ -T ₂ temperature range in weight loss curve of caking coal for temperature To select a caking filler material.   The caking filler is up to 900 ° C. in nitrogen at 3 ° C./min. In the mass reduction rate curve obtained by first-order differentiation of the mass reduction curve when the temperature is raised with time, the temperature at which the mass reduction rate is maximized is selected from caking fillers having a temperature of 400 ° C or higher. 2. A method for selecting a caking filler according to 2. The caking filler having the highest gas availability rate is selected from among those in which the gas availability rate of the caking filler in the T ₁ -T ₂ temperature range is equal to or higher than the volatilization rate of caking coal. The method for selecting a caking filler according to any one of the above. A method for producing a high-strength coke by adding a caking filler to caking coal, and producing a high-strength coke, the maximum shrinkage temperature T ₁ and the maximum expansion temperature of the caking coal according to the expansibility test method described in JIS M8801 T ₂ is obtained, and the mass reduction rate of each caking filler in the temperature range of T ₁ -T ₂ is obtained as a gas availability rate from the mass reduction curves of plural kinds of caking fillers measured in advance. A method for producing high-strength coke, characterized by selecting and adding a caking filler that makes the gas available rate equal to or higher than the volatilization rate of caking coal in the T ₁ -T ₂ temperature range. Volatilization rate of coking coal in the T ₁ -T ₂ temperature range, according to claim 5 which is a mass reduction rate of the caking coal in T ₁ -T ₂ temperature range in weight loss curve of caking coal for temperature Manufacturing method of high strength coke.   The caking filler is up to 900 ° C. in nitrogen at 3 ° C./min. In the mass reduction rate curve obtained by first-order differentiation of the mass reduction curve when the temperature is raised with time, the temperature at which the mass reduction rate is maximized is selected from among caking fillers having a temperature of 400 ° C. or more. Item 7. The method for producing high-strength coke according to Item 5 or 6. The caking filler with the highest gas availability rate is selected and added from among those in which the gas availability rate of the caking filler in the T ₁ -T ₂ temperature range is greater than or equal to the volatilization rate of caking coal. The manufacturing method of the high intensity | strength coke in any one of 5-7.

Images