JP5742650B2 - Molded coke manufacturing method and molded coke manufactured by the method - Google Patents

Description

  The present invention mainly relates to a method for producing a small coke for a blast furnace capable of blending a large amount of poor quality coal.

  Conventionally, many techniques have been developed for producing high-strength coke using inferior coal having poor caking properties or no caking properties.

The present inventors have also disclosed in Patent Document 1 a method for producing a small coke having a drum strength index DI ¹⁵⁰ ₁₅ of 70 or more by a chamber coke oven by adjusting coal blending or the like.

In the method for producing a small coke disclosed in Patent Document 1, it is necessary to blend a second coal having a volatile content VM of 30% or more and a total expansion rate of 60% or more at a ratio of 20% or more. there were.
Such coal is not expensive strong caking coal, but is caking coal, and its price tends to increase. For this reason, the coke which can mix | blend much more coal with poor caking property, and its manufacturing method are calculated | required.

  Further, as exemplified in Non-Patent Document 1 and Patent Document 2, as a method of producing coke having strength that can withstand the use of a blast furnace even if a large amount of inferior coal such as non-slightly caking coal is used, raw material coal is used. A forming coke method in which a mixture is formed into briquette-shaped charcoal (also simply referred to as briquette) and heated in a vertical shaft furnace to dry distillation is conventionally known.

  In Non-Patent Document 1, in order to produce molded coke having a necessary quality using non-caking coal as a main raw material, when the formed briquette is subjected to dry distillation, the rate of temperature rise is shown by boundary lines T2 and T1-T3 shown in FIG. In particular, the softening and melting temperature range of coal in which the temperature of the briquette center is in the range of 400 to 500 ° C, and also in the range of 500 to 700 ° C. In the contraction stage after the re-solidification temperature, the temperature rise rate is controlled to be lower than the boundary line T3 in FIG. 4 to prevent the briquettes from being blistered or cracked.

  Moreover, in patent document 2, 10-70 wt% of non-slightly caking coal whose caking power index is 50 to 80% and volatile matter content VM is less than 10 to 25% is mixed with respect to all raw coking coal. In addition, a non-slightly caking coal having a caking strength index of 50 to 80% and a VM of 25 to 35% is blended in an amount of 0 to 80 wt% with respect to all the raw coke of the formed coke, and the caking strength index is 80 to 95. %, VM is 15-30% caking coal blended with 50-10 wt% of all coking coal raw coal, coal tar, pitch and a binder consisting of one or more heavy petroleum oils It has been shown that high strength molded coke can be obtained by using coking charcoal added and pressure molded.

  In the conventional method for producing coke as described above, it is intended to produce a coke lump having a particle size of, for example, 40 mm or more and 60 mm or less (hereinafter referred to as a large coke) and producing a high strength coke. Since the purpose of this study is to examine dry distillation conditions and raw material conditions, there is a limit to the combination of a large amount of inferior coal. Further, it has not been conventionally studied to apply the formed coke method to the production of small coke having a highly reactive particle size of 40 mm or less.

JP 2010-95711 A Japanese Unexamined Patent Publication No. 7-263849

“Development of molding coke production method”, Steel Research No. 299 (1979), p. 19

  Accordingly, in the present invention, in the small coke used to promote a reduction reaction by substituting a part of ordinary coke in a blast furnace, poor quality coal having poor caking properties or not having caking properties. It is an object to be able to produce a small amount of coke with a high yield by blending more.

In the method for producing a small coke disclosed in Patent Document 1, since the drum strength index DI ¹⁵⁰ ₁₅ is 70 or more, it is considered that there is a limit to the use of poor quality coal.
Thus, focusing on the formed coke method, which is a technology for producing coke that can withstand the use of a blast furnace using inferior coal, the production of small coke by the formed coke method has been studied.
As a result, it has been found that small coke can be produced with high yield when inferior quality coal is used by adjusting the rate of temperature rise during dry distillation according to the volatile content VM of the blended coal.
The gist of the present invention thus made is as follows.

(1) the total expansion ratio of 20% or less of the briquette molded using the coal blend, making the molded coke dry distillation to a particle diameter 40mm following nodules in shaft furnace, the dry Tometoki the briquette The temperature increase rate while the center temperature Tc is 200 to 700 ° C. is selected from the following conditions (a) or (b) corresponding to the value of the volatile content VM of the blended coal used as a raw material A method for producing molded coke.
(A) When the VM value ≦ 34.5%, and T ° C. / min or more, which is defined by the following equation ^{T = 0.0001225 × Tc 2 -0.1418 ×} Tc + 46.18
(B) 34.5% <When the VM value still shall be the 1 ° C. / min or more,% of the VM value means mass%.
(2) Molded coke produced by the production method described in (1) above using blended coal having a total expansion rate of 20% or less, the particle size is adjusted to ₁₅ to 40 mm, and the drum strength index DI ¹⁵⁰ ₁₅ Is a molded coke characterized by being 40 or more.
(3) Further, the coke reactivity index CRI is 40 or more, the molded coke according to (2) above, wherein the coke reactivity index CRI is 40 or more.

  According to the present invention, a highly reactive small coke can be produced by using more inferior coal than in the past.

It is a figure which shows the pattern of the temperature increase rate used in the test which looks at the influence of the temperature increase rate with respect to a small coke yield. It is a figure which shows the boundary line used as the lower limit of the temperature increase rate when the VM value of blended coal is 34.5% or less. It is a figure which shows the pattern of the temperature increase rate used by the another test which sees the influence of the temperature increase rate with respect to a small coke yield. It is a figure which shows the appropriate range of the conventional temperature increase rate.

  The present inventors have intensively studied the application of the forming coke method in the production of small coke. As a result, when small coke is produced using the formed coke method, the behavior of the raw material briquette against blistering and cracking is different from that when large coke is produced, and At that time, it has been found that if a heating rate is appropriately selected, a small amount of formed coke can be produced at a high yield while blending more inferior quality coal.

  The conventional method for producing formed coke is to produce a large coke as described above. As shown in Non-Patent Document 1, the hatched line in FIG. 4 is shown in the range where the briquette center temperature Tc is 200 to 700 ° C. The heating rate was adjusted to enter the appropriate zone.

The reason for this is that in the softening and melting temperature range of 400 to 500 ° C., if the rate of temperature rise is too fast, briquette blisters cause cracks and cracks, and the crushing strength of the formed coke decreases. This is to prevent cracks and cracks due to briquette shrinkage at the shrinkage stage of 500 ° C. to 700 ° C. immediately after the solidification temperature.
In addition, when the briquette center temperature Tc is 200 ° C., it has been confirmed that the briquette surface temperature reaches 400 ° C. and starts softening and melting. The heating rate was adjusted to enter.

However, the inventors of the present invention, in the production of small coke using inferior coal as a blended raw material, the faster the heating rate, the better the production yield of small coke, the faster the heating rate. Also found no problem caused by briquetting blisters.
Below, the test result from which the knowledge was acquired is demonstrated.

  Four types of blended coals A, B2, C, and E shown in Table 1 were prepared and subjected to dry distillation using a method in which a coal raw material was subjected to dry distillation by a formed coke method to be coke. A has a total expansion coefficient TD of 10% and a volatile content VM of 25%, B2 has a total expansion coefficient TD of 5% and a volatile content VM of 32%, and C has a total expansion coefficient TD of 1% and a volatile content. E is a blended coal with a content VM of 35%, E with a total expansion coefficient TD of 0% and a volatile content VM of 36%.

  First, a binder (soft pitch) was added to the blended charcoal at an external number of 8% by mass and molded into briquettes having an average particle size of about 50 mm to obtain a charging raw material. Here, since the volatile matter content VM of the soft pitch is about 70% by mass, the volatile content of the formed coal obtained by adding the soft pitch to the blended coal is 28.3% by mass, 34% for A, B2, C, and E, respectively. 0.8 mass%, 37.6 mass%, and 38.5 mass%. Subsequently, this briquette was carbonized in a shaft furnace.

Here, four conditions indicated by P1, P2, P3, and P4 in FIG. 1 were used as the temperature raising conditions of the briquette center temperature Tc during heating.
The temperature rise patterns P1, P2, and P3 are conditions where the temperature rise rate is higher than that of the T1-T3 line in Non-Patent Document 1, and P4 is the temperature rise in the region of Non-Patent Document 1 surrounded by the T2 line and the T1-T3 line. Is speed.
The average heating rate during the heating when the center temperature Tc of the briquette is 200 to 700 ° C. is P1: 33 (° C./min), P2: 20 (° C./min), and P3: 10 (° C./min), respectively. , P4: 6 (° C./min).

  Further, although not shown in FIG. 1, the test was performed also with the pattern P5 (the briquette center temperature Tc during heating was an average rate of temperature increase of 3 ° C./min at 200 to 700 ° C.) and the pattern P6 (the same 1 ° C./min). Carried out.

Here, when the relationship between the briquette center temperature Tc and the briquette center temperature increase rate T ° C./min is obtained in each temperature increase pattern of P1, P2, P3, and P4, T is expressed by the following equation as a function of the briquette center temperature Tc. Represented.
P1: T = 0.00016655 × Tc ² −0.2255 × Tc + 96.19
P2: T = 0.00019814 × Tc ² −0.2301 × Tc + 78.76
P3: T = 0.0001225 × Tc ² −0.1418 × Tc + 46.18
P4: T = 0.0001225 × Tc ² −0.1418 × Tc + 42.18

The obtained molded coke was subjected to impact of 30 revolutions with a drum tester, and then screened with 40 mm and 15 mm sieves. ) Yield (%).
The results are shown in Table 2.

From Table 2, it can be seen that the higher the volatile content of the blended coal and the higher the rate of temperature rise, the higher the yield of small coke (15-40 mm). As for A and B2, which have a low volatile content of blended coal, the yield of small coke (15-40 mm) is greatly improved at a temperature rising rate of P3 or higher, and a yield of 80% or higher is obtained.
On the other hand, with regard to C and E having high volatile contents, a small coke (15-40 mm) yield of 80% or more can be obtained even at a low heating rate.
Further, when compared at the same rate of temperature increase, there is a large difference between B2 having a volatile content of 32% and C having a volatile content of 35%, and the yield of C small coke (15-40 mm) is significantly higher than that of B2. I understand that.

  From the above, it has been found that small coke can be produced with a high yield by the forming coke method. Specifically, it has been found that small coke can be produced with a high yield by appropriately selecting the heating rate during dry distillation according to the volatile content (VM) of the blended coal.

  In addition, although the case where it evaluated by the yield of 15-40 mm as an index | index which evaluates a small coke yield is illustrated above, the particle size of the small coke actually used is not limited to 15-40 mm, how Whether to use small coke in a wide particle size range depends on the furnace volume and operating conditions of the blast furnace.

For example, a case where a particle size range of about 15 to 25 mm is used can be assumed. In that case, the obtained formed coke is subjected to an impact of 30 revolutions with a drum tester, and then sieved with 25 mm and 15 mm. Sieve and small coke (15-25 mm) yield can be evaluated. By the way, the percentage of the sample mass of 15-25 mm to the mass of the original coke sample was defined as the small coke (15-25 mm) yield (%).
The results are shown in Table 3.

From Table 3, it can be seen that the yield of small coke (15-25 mm) tends to increase as the volatile content increases and the rate of temperature increase increases. For A and B2, which have low volatile content, the yield of small coke (15-25 mm) is greatly improved at a temperature rising rate of P3 or higher.
On the other hand, for C and E having a high volatile content, a high coke coke (15-25 mm) yield can be obtained even at a low temperature rise rate.
Further, when compared at the same rate of temperature increase, there is a large difference between B2 with a volatile content of 32% and C with a volatile content of 35%, and the yield of C small coke (15-25 mm) is significantly higher than that of B2. I understand that.
As described above, it was confirmed that the small coke (15-25 mm) yield also showed the same tendency as the small coke (15-40 mm) yield shown in Table 2.

  The present invention has been made by further study based on the above knowledge, and the matters constituting the present invention will be further described below.

(Combination of raw material coal)
In the present invention, as described above, an object is to use a large amount of inferior coal.
Specifically, blended coal having a total expansion coefficient TD of 20% or less is used. In general, the lower the caking property, the cheaper the coal price is. Therefore, in order to further lower the price of the raw material coal for producing coke, the total expansion rate is preferably 10% or less, or the total expansion rate may be 0%.
In the present invention, since the briquette center temperature increase rate is made faster than before, it is possible to produce formed coke even when using coal having such a low total expansion rate.
That is, in the present invention, inferior coal having poor caking properties or having no caking properties is used in a large amount as a blended raw material, and a coal blend having a total expansion rate of 20% or less is obtained. There is no problem with briquetting blisters.

In addition, blended coal refers to the raw material coal for making coke, and refers to the coal which mixed 1 type or 2 types or more of coal.
Moreover, the total expansion coefficient TD of the blended coal is a value obtained by a weighted average from the total expansion coefficient TD of each coal constituting the blended coal and the blend ratio of each coal. Since the total expansion coefficient TD has no additivity, it differs from the TD actual measurement value of the blended coal. In addition, the total expansion coefficient TD of coal is measured by the expansibility test method (dilatometer method) described in JIS M8801.

(Temperature increase rate during heating)
Based on the above test results, the present inventors conducted detailed experiments on the relationship between the value of the volatile content VM of the coal blend and the rate of temperature increase. As a result, when the VM value exceeds 34.5%, there is no special limitation on the rate of temperature increase, and when the VM value is 34.5% or less, the temperature rise according to the center temperature Tc of the forming coal. It was found that there was a lower speed limit.
And further examination, a small lump by adjusting the temperature increase rate while the center temperature Tc of the forming coal at the time of heating at the time of dry distillation is 200-700 ° C. according to the VM value as follows We found that coke can be produced with high yield. For example, as described above, it was confirmed that a yield of 84% or more small coke (15-40 mm) was obtained.

(1) When VM value ≦ 34.5%, T ° C./min or more defined by the following formula.
T = 0.0001225 × Tc ² −0.1418 × Tc + 46.18
In addition, T is represented by the curve described by the thin line in FIG.
(2) When 34.5% <VM value, it is set to 1 ° C./min or more.

Moreover, if it is going to improve the yield of small coke, it should just raise the temperature increase rate of the center temperature Tc of forming coal.
For example, as described above, if a small coke (15-40 mm) yield of 87% or more is to be obtained, the rate of temperature increase while the center temperature Tc of the forming coal during dry distillation is 200 to 700 ° C.,
When VM value ≦ 34.5%, it is set to T ° C./min or more defined by the following formula,
T = 0.00019814 × Tc ² −0.2301 × Tc + 78.76
When 34.5% <VM value, it may be 3 ° C./min or more.

Further, for example, as described above, if a yield of 90% or more of small coke (15-40 mm) is to be obtained, the rate of temperature increase while the center temperature Tc of the coal coal during dry distillation is 200 to 700 ° C. is increased. ,
When VM value ≦ 34.5%, it is set to T ° C./min or more defined by the following formula,
T = 0.00016655 × Tc ² −0.2255 × Tc + 96.19
When 34.5% <VM value, it may be 6 ° C./min or more.

Here, the VM of the blended coal is an actual measurement value of the blended coal VM. However, since the VM has an additivity, a weighted average is obtained from each VM constituting the blended coal and the blending ratio of each coal. Since it is equal to the value obtained by (2), either one may be used. This VM does not include the binder VM added when producing coal.
The briquette center temperature Tc is the temperature at the center of the width, length and height of the briquette. In a test dry distillation furnace that can simulate the actual process, a thermocouple is installed at the center of the briquette and the temperature is measured. Can be evaluated.

  When producing by the coke production method using blended coal with a total expansion rate of 20% or less, small coke is produced with a high yield when it is produced in the above temperature rise rate range divided by the VM value of the blended coal. The reason why this is possible is inferred as follows.

When coal is carbonized (heated in the absence of oxygen), it will be pyrolyzed, causing side chain cleavage of aromatic rings and polycondensation of aromatic rings, and volatiles (hydrocarbons such as methane and ethane, CO, hydrogen, tar, etc.) are generated.
Due to this polycondensation reaction, coal shrinks greatly during the heating process. Coal is a heterogeneous material and has a temperature distribution inside the formed coal, so the shrinkage is not uniform. Distortion occurs due to the non-uniform shrinkage, and stress is generated, resulting in cracks in the coke.
Therefore, the higher the VM VM value and the higher the rate of temperature increase, the greater the amount of shrinkage per unit time, so that more cracks occur, which makes it possible to increase the yield of small coke. it is conceivable that.

In addition, the reason why there is an appropriate heating rate for the VM VM value is not clear, but is presumed as follows.
In the case of VM value ≦ 34.5%, in order to produce small coke with a high yield, a higher rate of temperature rise than the above formula is required, but this is not the case with blended coal with VM value ≦ 34.5%. It is surmised that the shrinkage behavior accompanying the thermal decomposition changes greatly and the amount of cracks increases abruptly when the temperature rise rate is higher.
In addition, since the lower limit of VM value is decided by the brand | brand used, it does not specifically limit, A VM value is about 20 mass% or a VM value is about 15 mass%.

On the other hand, in the case of over 34.5% VM, small coke can be produced with a high yield even at a low rate of temperature rise. However, if VM exceeds 34.5%, the shrinkage behavior due to thermal decomposition changes greatly. Thus, the amount of cracks increases rapidly, and it is assumed that many cracks are generated even at a small temperature increase rate.
The lower limit of the rate of temperature increase is not particularly limited, but a practical value is 1 ° C./min.
Further, the upper limit value of the VM value is also not particularly limited because it is determined by the brand to be used. The VM value is about 40% by mass, the VM value is about 45% by mass, or the VM value is about 50% by mass. The thing can be illustrated.

  By the way, the reason for prescribing an appropriate rate of temperature increase for the blended coal VM value that does not contain the binder VM is that the cracks that occur in the coke are derived from the volatile matter that occurs during the thermal decomposition of the coal. This is based on the fact that it is unrelated to the VM of the binder.

  In addition, the upper limit of the temperature increase rate while the briquette center temperature Tc is in the range of 200 to 700 ° C. is not particularly limited regardless of the total expansion rate TD and VM of the blended coal.

(Target coke strength)
For small coke formed in the present invention, a target drum strength index DI ¹⁵⁰ ₁₅ of 40 or more is sufficient.
In Patent Document 4, when the drum strength index DI ^0.99 ₁₅ is less than 70, because it can decrease the breathability caused destruction and powdering of coke and a decrease in reduction efficiency results had a DI ^0.99 ₁₅ 70 or more .
On the other hand, in the small coke produced by the method for producing molded coke of the present invention, even if DI ¹⁵⁰ ₁₅ is less than 70, if it is 40 or more, it can be sufficiently used in a blast furnace. In addition, the upper limit of DI ¹⁵⁰ ₁₅ is not particularly defined, and a larger value is more preferable.

The reason is presumed as follows.
The coke produced by the molded coke production method is different in shape from the coke produced by the chamber furnace method. Since the briquette coal is used in the molded coke manufacturing method, the coke manufactured by this method has a shape with fewer corners compared to the coke manufactured by the chamber furnace method.
On the other hand, since the drum strength test is evaluated by a mass ratio on a sieve of 15 mm after an impact of 150 revolutions is applied by a drum tester, information on the powder generation rate at the initial impact is not shown. The coke produced by the molded coke production method has a small number of corners, and is considered to have a low powder generation rate at the initial impact. For this reason, even if the drum strength index is low, the amount of powder generated at the initial stage is small, and if the drum strength index is 40 or more, it is considered that the drum strength index can be used in a blast furnace.
The drum strength index DI ¹⁵⁰ ₁₅ is a 15 mm sieving index after 150 rotations measured by the drum method of the coke rotation strength test method described in JIS K2151.

(Method for producing molded coke)
In the production of the formed coke of the present invention, a normal formed coke manufacturing method is applied except for the blended coal and the heating rate during heating.
As outlined above, raw coal is blended as described above, the blended coal is formed into raw briquettes, the briquettes are charged into a vertical shaft furnace, heated and dry-distilled to form coke.

Inferior raw material coal is stored in a plurality of hoppers for each coal, and is cut out from each hopper so as to have a predetermined blending ratio. At that time, a raw material adjusted to a predetermined particle size in advance may be placed in a hopper, or may be cut out from the hopper and then pulverized by a pulverizer to obtain a predetermined particle size.
The particle size of the raw material is preferably −3 mm 85% or more, more preferably −3 mm 95% or more, and still more preferably −1.5 mm 95% or more.

If necessary, a binder such as pitch or a catalyst such as limestone (alkaline earth metal compound) is added to the blended coal thus blended, kneaded with a kneader, sent to a molding machine, and the average grain Molded into a raw material briquette having a diameter of 10 to 80 mm.
Next, the raw material briquette is charged into a vertical shaft furnace, heated and dry-distilled to form formed coke.

The particle size of the product coke is 15 to 40 mm. This is because if the particle size is smaller than 15 mm, it becomes a factor that hinders ventilation in the blast furnace.
On the other hand, when the particle size exceeds 40 mm, the specific surface area becomes small, and unreacted coke descends to the lower part of the blast furnace and becomes a factor that impedes aeration.

About this particle size range, it confirmed as follows and discovered said range.
That is, the present inventors examined the relationship between coke particle size and reactivity.
Incidentally, the coke reactivity index CRI is widely known as a reactivity index. The coke reactivity index CRI is preferably 40 or more. The reason is that if the CRI is less than 40, the reactivity of the coke is not sufficient, and the unreacted coke falls to the lower part of the blast furnace, which is pulverized and inhibits aeration.
In this CRI, 200 g of coke prepared to have a particle size of 20 ± 1 mm was reacted for 2 hours under the conditions of a reaction temperature of 1100 ° C. and a CO ₂ gas flow rate of 5 Nl / min. Is a value calculated by the following equation using its mass.
CRI = ((200−A) / 200) × 100 (%)

However, here, in order to examine the relationship between the coke particle size and the reactivity, the particle size was not adjusted to 20 ± 1 mm, but according to the CRI measurement method. Namely, the test was carried out reacting 4 hours lump coke at 1100 ° C. in a CO ₂ atmosphere. As a sample, molded coke having a particle size of 20 mm, 30 mm, 40 mm, and 50 mm was used. As a result, the reaction rates after completion of the experiment were 100%, 70%, 50%, and 37%, respectively.
In this way, it is confirmed that the specific surface area decreases and the reaction rate decreases when the sample size is large. The coke with a particle size of 50 mm has a reaction rate of less than 40% after the experiment, and the reaction coke is blast furnace. It was confirmed that it could descend to the bottom, pulverize, and hinder ventilation.

Furthermore, the relationship between the heating rate of the forming coal and the CRI of the obtained coke (ordinary method in which the particle size was adjusted to 20 ± 1 mm) was also examined.
As a result, it has been experimentally found that the CRI of the obtained coke tends to increase as the heating rate of the forming coal increases. The reason is considered to be that as the volatile matter of the coal is higher, the amount of the volatile matter generated per unit time with thermal decomposition increases, fine pores are formed, and coke having a high specific surface area is generated.

  In particular, when the blended coal of more than VM 34.5% is used to produce the coke, a high CRI coke can be obtained even at a low temperature increase rate. The reason for this is not clear, but the coal of VM34.5% or more is significantly different in structure from the coal of VM34.5% or less, the behavior of volatile matter generation accompanying pyrolysis changes greatly, and even if the heating rate is low, It is presumed that the amount of volatile matter generated per unit time with decomposition is large and the fine pore structure generated in coke is large.

Moreover, adjustment of the temperature increase rate of the briquette center at the time of a heating is implemented as follows.
First, in a test carbonization furnace that can simulate an actual process, the relationship between the briquette center temperature and the ambient gas temperature is obtained in advance, and the temperature rise conditions for the ambient gas temperature that can achieve the desired rate of temperature rise at the briquette center are set. I ask for it. Next, in the actual process, the temperature of the heated gas and / or the gas flow rate are adjusted so as to satisfy the temperature increase condition obtained above.
Thereby, a highly reactive small coke can be manufactured using much inferior quality charcoal compared with the past.

  The present invention is characterized by the method for producing molded coke described above and the small coke formed by using the method, and further, based on the examples, the feasibility and effect of the present invention. Will be described.

As shown in Table 4, a blended coal having a volatile content VM and a total expansion coefficient TD is prepared, pulverized to 3 mm or less to 90%, and then 8% by mass (external number) of soft pitch is added as a binder. Coking charcoal to be a raw material briquette having an average particle diameter of 40 mm was produced.
Next, the raw material briquette was dry-distilled to 900 ° C. in a vertical shaft furnace to form a small coke.

  As conditions for raising the center temperature Tc of the briquette during heating, four conditions indicated by H1, H2, H3, and H4 in FIG. 3 were used.

  The temperature rising patterns H1, H2, and H3 shown in FIG. 3 are conditions where the temperature rising rate is higher than the temperature rising patterns P1, P2, and P3 also shown in FIG. 1, and H4 is T2 of Non-Patent Document 1. It is the rate of temperature increase in the region surrounded by the line and the T1-T3 line. The average rate of temperature rise during the heating when the center temperature Tc of the briquette is 200 to 700 ° C. is H1: 34 (° C./min), H2: 21 (° C./min), and H3: 11 (° C./min), respectively. , H4: 6 (° C./min).

The obtained small coke (15-40 mm) yield (%), small coke (15-25 mm) yield (%), reactivity index CRI and drum strength index DI ¹⁵⁰ ₁₅ were measured, together with the production conditions. It was described in.

In Examples 1 to 25 of the present invention, a small coke (15-40 mm) yield of 80% or more is obtained. On the other hand, the small coke (15-40 mm) yield of the comparative example was less than 70%.
Moreover, all of Examples 1 to 25 of the present invention were cokes having a drum strength index DI ¹⁵⁰ ₁₅ of 40 or more.
Incidentally, coke of CRI 40 or more was obtained in all of inventive examples 1 to 25.

Claims (3)

The molded charcoal molded using the total expansion ratio of 20% or less coal blend, making the molded coke dry distillation to a particle diameter 40mm following nodules in shaft furnace, the center temperature Tc of the shaped coal dry Tometoki Is selected from the following conditions (a) or (b) corresponding to the value of the volatile content VM of the blended coal used as a raw material: Coke production method.
(A) When the VM value ≦ 34.5%, and T ° C. / min or more, which is defined by the following equation ^{T = 0.0001225 × Tc 2 -0.1418 ×} Tc + 46.18
(B) 34.5% <When VM value shall be the 1 ° C. / min or more A molded coke produced by the production method according to claim 1 using a blended coal having a total expansion rate of 20% or less, wherein the particle size is adjusted to ₁₅ to 40 mm, and the drum strength index DI ¹⁵⁰ ₁₅ is 40 or more. Molded coke characterized by being.   Furthermore, the coke reactivity index | exponent CRI is 40 or more, The shaping | molding coke of Claim 2 characterized by the above-mentioned.

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