JP5052866B2 - Method for producing blast furnace coke - Google Patents

Description

  The present invention relates to a method for producing coke for blast furnace, and more particularly, to a method for producing coke for blast furnace by drying and preheating blended coal and then subjecting it to dry distillation in a chamber furnace type coke oven.

  In the normal iron making process, coke and iron-containing raw materials such as sintered ore and iron ore are charged in layers from the top of the blast furnace, and high-temperature oxygen-containing gas is blown from the tuyere at the bottom of the blast furnace. Carbon dioxide gas and carbon monoxide gas are generated by a combustion reaction, and iron oxide reduction reaction is performed while heating and melting the iron-containing raw material to obtain pig iron.

  In this way, the role of coke for blast furnace is to maintain a good reducing material for reducing iron oxide in the blast furnace, a heat source for heating and melting iron oxide, and good reaction efficiency between iron oxide and reducing gas in the blast furnace. There are four points: a ventilation material and a liquid-permeable material. For this reason, as a characteristic of blast furnace coke, coke having a high strength and a large particle size is required in order to maintain aeration and liquid permeability.

  Normally, in a coke oven, coke is produced by adjusting the furnace temperature of the coke oven to about 1100 to 1250 ° C. according to coke quality and productivity. Generally, the particle size of coke decreases as the furnace temperature of the coke oven increases.

  Also, in order to increase the productivity of the coke oven, when the coal is dried and then preheated to a higher temperature, charged into the coke oven and dry-distilled, the coke particle size tends to decrease.

  In recent years, as a method of reforming and pretreating coal to improve low-grade inferior coal such as non-slightly caking coal and improve coke strength, coal is heated to 300 ° C or higher in a fluidized bed, While rapidly heating to below the softening start temperature, classify into pulverized coal and coarse coal, and form pulverized coal, or the pulverized coal and coarse coal after the classification, further in an airflow rapid heater, There has been proposed a blast furnace coke manufacturing method in which rapid heat treatment is performed in a temperature range of 300 ° C. or more and not more than the softening start temperature of coal, and then pulverized coal is formed (see, for example, Patent Document 1).

  This method makes it possible to produce high-strength coke using raw coal containing a large amount of inexpensive inferior coal such as non-slightly caking coal. However, when carbonizing rapidly heat-treated coal in a coke oven, the temperature distribution in the coke oven, particularly in the furnace width direction, becomes steep, so the amount of cracks generated in the coke mass increases due to thermal contraction, The problem of reducing the particle size of coke becomes significant.

  As a method of controlling the coke particle size, the coke shrinkage is measured from the amount of shrinkage from the resolidification temperature to the heating temperature by heating to a heating temperature exceeding the resolidification temperature of the raw coal blend, and the coke is calculated from this measured value. A method is proposed in which the particle size is estimated, and the blending ratio of each single coal in the blended coal is adjusted so that the estimated value is equal to or greater than the target coke particle size (for example, see Patent Document 2). Yes. However, using this method, it has been difficult to sufficiently increase the coke particle size only by adjusting the blending ratio of each simple coal within a limited range of coal types.

  Moreover, conventionally, in order to increase the particle size of coke for blast furnace, a method of adding coke breeze to the raw material blended coal (see, for example, Patent Document 3), or adding a petroleum pitch along with the powder coke to the raw material blended coal. There is known a method (for example, see Patent Document 4). However, the addition of powdered coke to the raw coal blend increases the particle size of the blast furnace coke, but greatly reduces the coke strength. By adding a caking agent such as petroleum pitch together with powdered coke to the blended coal, it is possible to suppress the coke strength decrease due to the addition of powdered coke to some extent, but maintaining sufficient coke strength stably It becomes difficult.

  In particular, when coke is produced by preheating raw material blended coal or by rapid heating and dry distillation in a coke oven, reducing the coke particle size is a problem. This is not preferable because it causes a drastic decrease in the temperature.

JP 2005-82790 A JP-A-2005-232349 JP 60-69192 A JP-A-6-17056

  The present invention dries and preheats the blended coal, adds a caking additive to the blended coal, and carbonizes in a coke oven, thereby shortening the carbonization time and maintaining a high productivity while maintaining a large particle size. It aims at providing the manufacturing method of the coke for blast furnace which can manufacture the coke of this.

The gist of the present invention is as follows.
(1) After blending coal containing 30 to 70% by mass of non-finely caking coal and the balance consisting of caking coal, and further preheating, a mixture of pulverized coal and coarse coal at a temperature of 150 to 300 ° C. , soft pitch, a percentage of the mixture of the pulverized coal and the coarse coal, 2-10 wt% additives, mixing, re-solidification temperature is 460 ° C. of the mixture of pulverized coal and coarse coal containing the soft pitch After making it above, it is charged into a coke oven and dry-distilled, The manufacturing method of coke for blast furnaces characterized by the above-mentioned.
(2) The mixture of pulverized coal and coarse coal at a temperature of 150 to 300 ° C. is obtained by drying the blended coal and further preheating, then classifying it into pulverized coal and coarse coal, and agglomerating and agglomerating the pulverized coal. The method for producing coke for blast furnace according to (1) above, wherein the mixture is charcoal, and the coarse coal is rapidly heated and then the agglomerated coal and coarse coal are mixed.

According to the present invention, even when using coal that is preheated to 80 to 350 ° C., drying the coal, it was preheated at a temperature of 80 to 350 ° C., by the addition of soft pitch or Ranaru caking material The re-solidification temperature of coal can be raised, and coke having a large particle size can be produced by dry-distilling the coal to which the binder has been added in a coke oven.

  First, the technical idea of the present invention will be described.

  Coke is produced by the following method.

  In general, the coal blended in the coking chamber of the coke oven is heated to 1100 to 1250 ° C. from the adjacent combustion chamber via the furnace wall bricks on both sides, and the coking of coal is performed near the furnace wall of the coking chamber. Proceed from the center towards the center. At the beginning of dry distillation, first, the coal in the vicinity of the furnace walls on both sides is softened and melted to coke, and then the surface layer is thermally shrunk in a direction parallel to the furnace wall surface, so that coke as shown in FIGS. A longitudinal crack in the direction perpendicular to the furnace wall occurs in the lump surface layer, and further, as the dry distillation proceeds, the crack grows toward the center of the carbonization chamber.

  Further, as the carbonization progresses, the temperature distribution from the furnace wall side to the center of the carbonization chamber causes thermal contraction in the direction perpendicular to the furnace wall surface, so that the coke mass as shown in FIGS. Lateral cracks are generated in the direction parallel to the furnace wall. It is considered that the final coke particle size is determined by the form of longitudinal cracks and transverse cracks (crack length, number, crack interval, etc.) in the coke mass generated in the coal carbonization process.

  According to the study by the present inventors, in order to shorten the carbonization time of the coke oven and improve the productivity of the coke oven, when preheating the blended coal to a high temperature and charging the coke oven, As shown in FIG. 3, it was confirmed that there is a problem that the particle size of the coke decreases as the preheating temperature of the blended coal increases.

  Therefore, in order to investigate this cause, the present inventors pre-heated the blended coal to a high temperature and charged it into a coke oven, when dry distillation, and the occurrence of longitudinal cracks and transverse cracks in the coke lump, The relationship with the preheating temperature of charcoal was investigated in detail. As a result, the following became clear.

  As the preheating temperature of the blended coal rises, the temperature difference in the height direction of the blended coal between the furnace top and the vicinity of the furnace bottom and the center of the furnace, where heat is easily radiated, becomes smaller. Becomes wider and longitudinal cracks are reduced. However, on the contrary, the progress of dry distillation is accelerated by preheating, so the temperature distribution from the furnace wall side to the center of the carbonization chamber becomes steep, and the thermal shrinkage acting in the direction perpendicular to the furnace wall surface increases. As a result, the interval between transverse cracks generated in the coke mass is narrowed, and the transverse cracks are extremely increased.

  From these facts, it was confirmed that the cause of the decrease in the coke particle size was a sudden increase in the number of transverse cracks when the blended coal was preheated to a high temperature and charged in a coke oven and dry-distilled. .

  Based on these findings, the present inventors diligently devised a method for increasing the coke particle size by preheating the blended coal, charging it into the coke oven, and suppressing the occurrence of transverse cracks during dry distillation. investigated.

  FIG. 4 shows heating temperature and fluidity of blended coal A and blended coal A in which 10% by mass of soft pitch and petroleum pitch are added as caking agents each having a boiling point and a softening point higher than those of normal tar. And the results of measuring the resolidification temperature.

  Here, the blended coal A is a blended coal of non-slightly caking coal: 50% by mass and caking coal: 50% by mass.

  The fluidity of the coal shown in FIG. 4 is an example of a result of measurement according to a fluidity test method measured using a Gieseler plastometer described in JISM8801. A metal crucible (inner diameter 21.4 mm, depth 35.0 mm) into which a stir bar is inserted is filled with 5 g of a coal sample crushed to 425 μm (35 mesh) or less, and this metal crucible is placed in a metal bath. And heating at a heating rate of 3.0 ° C./min.

  The dial pulley with the same diameter as the drum pulley on the stirring bar and concentrically equipped with an indicator is tuned, and the scale of the indicator (360 degrees, 100 equal parts) moves with the temperature at that time. Plot every minute. Continue the measurement until the pointer stops moving and record the relationship between temperature and dial reading.

  From this, the softening start temperature (temperature when the stir bar starts to move continuously and reaches 1.0 ddpm) (° C.), maximum flow temperature (° C.), resolidification temperature (temperature when the stir bar stops) ( ° C), maximum fluidity (ddpm), and flow range.

  From FIG. 4, the resolidification temperature of the blended coal can be increased by adding a binder having a boiling point and a softening point higher than those of normal tar to the blended coal as compared to the case where this binder is not added. Recognize.

  In FIG. 5, each of blended coal A, blended coal B, and blended coal C has a heavy tar content (component content having a boiling point of 300 ° C. or higher) as a binder having a boiling point and a softening point higher than those of tar. 83.2 mass%) shows the relationship between the caking additive addition rate relative to the blended coal and the coke shrinkage during the dry distillation process.

  Here, the blended coal A is a blended coal of non-slightly caking coal: 70 mass%, caking coal: 30 mass%, and the blended coal B is a non-slightly caking coal: 50 mass%, caking coal: The coal blend is 50% by mass, and the coal blend C is a coal blend of non-slightly caking coal: 40% by mass and caking coal: 60% by mass.

The coke shrinkage shown in FIG. 5 was measured by the following method. That is, a sample of blended coal is inserted into a container, the sample in the container is heated from room temperature to a heating temperature T (° C.) higher than the resolidification temperature, and the volume V _R and temperature of the sample contents at the resolidification temperature. The volume VT of the sample contents at _T was measured, and the coke shrinkage ratio R (−) was determined based on the following formula (1).
R = (V _R −V _T ) / V _R (1)

  In general, the shrinkage at about 400 ° C. observed by such a test method is an apparent volume change in which coal softens and melts and voids between coal particles disappear, and is about 500 ° C. The contraction of the softened and melted coal at the time of resolidification is the contraction of the coal (strictly, semi-coke or coke).

  In addition, FIG. 6 shows the relationship between the caking additive addition rate and the coke particle size improvement effect when the heavy coal tar is added to the blended coal B shown in FIG.

ΔMS indicates the amount of change in the measured value MS of the coke particle size with respect to the reference value MS ₀ (= 46.0 mm) of the coke particle size, where + indicates an increase from the reference value and − indicates a decrease from the reference value. means. The measured value MS of the coke particle size is a measured value measured according to the coke particle size test method described in JIS K 2151 using a coke sample obtained by carbonization in a test carbonization furnace.

  From FIG. 5, by adding a caking agent having a boiling point and a softening point higher than those of normal tar to the blended coal, the coke shrinkage during dry distillation of the blended coal is reduced, and the effect of the addition of the caking additive is increased. Can be seen to increase.

  This is because by adding a caking additive having a boiling point and softening point higher than that of tar to the coal blend, the resolidification temperature of the coal blend increases, and this coal blend is preheated to a high temperature and charged into a coke oven. In the case of carbonization, it is considered that the temperature distribution from the carbonization chamber furnace wall side to the center portion becomes gentle, and as a result, the amount of heat shrinkage in the direction perpendicular to the furnace wall surface during the resolidification process is reduced.

  Further, from FIG. 6, in any blended coal, by adding a binder having a boiling point higher than that of tar, the coke particle diameter after dry distillation increases, and the effect of the addition of the binder addition ratio increases. Can be seen to improve.

  First, as shown in FIG. 5, the amount of heat shrinkage in the direction perpendicular to the furnace wall surface during the resolidification process is reduced by the addition of the binder, and secondly, the binder is used. This is probably because the adhesion of coal particles in the softening and melting process was enhanced and the coke lamination structure was strengthened, so that the occurrence of transverse cracks in the direction parallel to the furnace wall surface and the propagation of cracks were suppressed.

In addition, in FIG. 5 and FIG. 6, an example at the time of using heavy tar as a caking additive was shown .

  Based on the above knowledge, the present invention prevents coke particle size from decreasing when pre-heating blended coal to a high temperature and charging and dry distillation into a coke oven, while improving productivity and coke with a predetermined particle size. In order to produce the above, by adding a predetermined amount of a binder having a boiling point higher than that of tar to the preheated blended coal, (1) the resolidification temperature of the blended coal is increased, and the furnace wall during the resolidification process is added. In addition to reducing the amount of heat shrinkage in the vertical direction, (2) enhancing the adhesion between coal particles during the softening and melting process, strengthening the coke laminate structure, generating transverse cracks in the direction parallel to the furnace wall and propagation of cracks Is a technical idea.

The present invention is based on the above technical idea. In the method for producing coke for blast furnace, after the blended coal is dried and further preheated, a mixture of pulverized coal and coarse coal at a temperature of 150 to 300 ° C. in the soft pitch or Ranaru caking material, a percentage of the mixture of the pulverized coal and the coarse coal, adding 2 to 10 wt%, were mixed, the pulverized coal and the coarse coal containing pressure-sensitive binding material After the re-solidification temperature of the mixture is set to 460 ° C. or more, the coke oven is charged and dry-distilled.By carrying out the present invention, coke having a large particle size is maintained while maintaining coke strength. Can be manufactured under high productivity.

  In an embodiment of the present invention, the mixture of pulverized coal and coarse coal at a temperature of 150 to 300 ° C. is obtained by drying the blended coal and further preheating, then classifying the coal into pulverized coal and coarse coal, and lump the pulverized coal. A mixture of the agglomerated coal and the coarse coal may be used after the coarse coal is rapidly heated while being agglomerated and agglomerated. According to this embodiment, the pulverized coal is agglomerated into agglomerated coal, and the coarse coal is rapidly heated, thereby improving the caking property and expansibility of the coal during dry distillation, and increasing the coke particle size increase effect. In addition, the coke strength can be further increased.

  Moreover, it is preferable to use what the said combination charcoal contains 30-70 mass% of non-slightly caking coal, and the remainder consists of caking coal. The blended coal containing 30% by mass or more of the non-slightly caking coal has low caking property during dry distillation and high shrinkage, so that the effect of improving the coke strength and coke particle size by applying the present invention is the most. Since it exhibits, it is a preferable blended coal.

  Below, the characteristic features of the present invention and the reasons for its limitation will be described.

(Type of binder)
The present invention is, for the following reasons, the caking additive to be added to the preheated coal blend, and soft pitch or Ranaru caking material.

This Nebayuizai because both a high boiling point and softening point compared to caking material such as ordinary tar, solid at room temperature, was added the caking in the coal blend, when mixed, in coal blend, the caking additive is locally unevenly distributed, sufficient interaction between the coal particles and caking additive can not be obtained. However, when this caking material is added to and mixed with 150 to 300 ° C blended coal specified in the present invention, the fluidity of the caking additive is increased and uniformly dispersed in the blended coal. Proximity or bonded state.

  When charging into a coke oven and carbonizing in such a state, the caking additive increases the resolidification temperature of the blended coal by interacting with the coal particles, and is perpendicular to the furnace wall surface during the resolidification process. Reduce the amount of heat shrinkage in any direction, enhance the adhesion between coal particles during the softening and melting process, strengthen the coke laminate structure, and suppress the occurrence of transverse cracks and crack propagation in the direction parallel to the furnace wall As a result, the effect of improving the coke particle size is obtained.

  On the other hand, caking materials that have a low boiling point and are liquid at room temperature, such as tar, are not suitable for mixing with preheated high-temperature coal blends, and also increase the resolidification temperature of coal blends. The effect of reducing the amount of heat shrinkage in the direction perpendicular to the furnace wall surface during the resolidification process is small, so that the effect of expanding the coke particle size cannot be sufficiently obtained.

For the above reasons, in the present invention, the caking additive added to the preheated coal blend is usually obtained by distilling a soft pitch (coal tar) having a boiling point and a softening point higher than those of the caking additive such as tar. and at room temperature solid residue) or Ranaru caking material.

In the present invention, the heavy tar fraction preferably contains 80% by mass or more of a component having a boiling point at normal pressure of 300 ° C. or higher. The main component of the heavy fraction is more preferably composed of one or more of phenanthrene, anthracene, methylnaphthalene and fluoranthene. The soft pitch is preferably a softening point of 30 to 200 ° C..

(Blend coal temperature when adding binder)
In the present invention, for the following reasons, the temperature of the coal blend in when adding soft pitch or Ranaru caking material to 150 to 300 ° C..

As described above, a caking material effective for increasing the resolidification temperature of coal blend is usually a caking material having a higher boiling point and softening point than caking materials such as tar, and consisting of a soft soft solid at room temperature. It is. In order to increase the interaction between the binder and coal particles during dry distillation, such a binder is added to the coal blend, and in the state where the temperature of the coal blend is high, a binder composed of soft pitch is added, By mixing, it is necessary to uniformly disperse in the blended coal and to bring the binder into a state of being close to or adhered to the coal particles.

When the temperature of the blended coal when adding the binder composed of soft pitch is lower than 150 ° C., the binder is unevenly distributed in the blended coal, and the binder is uniformly approached or adhered to the coal particles. I can't. As a result, the interaction between the binder and coal particles increases the resolidification temperature of the blended coal, reduces the amount of heat shrinkage in the direction perpendicular to the furnace wall during the resolidification process, and reduces the coal particles during the softening and melting process. The effect of suppressing the occurrence of transverse cracks in the direction parallel to the furnace wall surface and the propagation of cracks cannot be sufficiently obtained by enhancing the adhesion between them and strengthening the coke laminate structure.

On the other hand, the temperature of the coal blend at the time of adding the binder composed of soft pitch increases and the dispersibility of the binder into the coal blend is promoted, but as shown in FIG. The temperature distribution from the center to the center becomes steep, and the amount of heat shrinkage in the direction perpendicular to the furnace wall surface during the resolidification process is increased. When the temperature of the blended coal at the time of adding the binder exceeds 300 ° C., coke grains due to an increase in the amount of thermal shrinkage in the direction perpendicular to the furnace wall during the resolidification process due to the above-mentioned effect due to the addition of the binder. It becomes difficult to suppress the decrease in diameter.

For the above reasons, in the present invention, the binder made of soft pitch is uniformly dispersed in the blended coal, the effect of the interaction with the coal particles is sufficiently exhibited, and the coke particle size is sufficiently increased. The temperature at the time of adding a caking additive to blended coal shall be 150-300 degreeC.

In order to further uniformly disperse the binder composed of the soft pitch having a high boiling point and softening point in the blended coal, promote the interaction with the coal particles, and further enhance the effect of the binder, The temperature at which the binder is added to the blended coal is preferably 200 ° C. or higher.

(Addition amount of binder)
In this invention, the addition amount of the caking additive which consists of a soft pitch with respect to the preheated combination charcoal (mixture of pulverized coal and coarse-grained coal) shall be 2-10 mass% from the following reasons.

  FIG. 7 shows the relationship between the resolidification temperature and the coke particle size improvement effect, and FIG. 8 shows the relationship between the amount of various binders added and the coke particle size improvement effect.

ΔMS indicates the amount of change in the measured value MS of the coke particle size with respect to the reference value MS ₀ (= 46.0 mm) of the coke particle size, where + indicates an increase from the reference value and − indicates a decrease from the reference value. means. The measured value MS of the coke particle size is a measured value measured according to the coke particle size test method described in JIS K 2151 using a coke sample obtained by carbonization in a test carbonization furnace.

As shown in FIGS. 7 and 8, in the coal blend amount of caking additive for (pulverized coal and mixtures coarse coal) is less than 2% by weight, relatively less boiling point and softening point of the viscosity Yuizai When adding a heavy tar fraction to the blended coal, it is possible to raise the resolidification temperature of the blended coal described above and sufficiently reduce the amount of heat shrinkage in the direction perpendicular to the furnace wall during the resolidification process. It becomes difficult, and the effect of increasing the coke particle size cannot be obtained sufficiently. Therefore, the amount of the caking additive added to the blended coal (mixture of pulverized coal and coarse coal) is 2% by mass or more.

  In addition, the effect of reducing the heat shrinkage in the direction perpendicular to the furnace wall during the re-solidification process by increasing the re-solidification temperature of the coal-blown coal is a caking effect on the coal blend (a mixture of pulverized coal and coarse coal). The addition amount of the material is preferably 5% by mass or more.

  On the other hand, when the amount of caking additive added to the blended coal (mixture of pulverized coal and coarse coal) exceeds 10% by mass, the amount of caking additive added per blended coal increases, and the coke oven charging density Therefore, it is difficult to stably secure the coke strength, which is not preferable. Moreover, the increase in the amount of caking additive increases the amount of carbon adhering to the furnace wall generated in the coke oven, increasing the load during coke extrusion, which is not preferable for coke oven operation.

For these reasons, in the present invention, the effects of the above Ki軟 pitch or Ranaru caking, in order to sufficiently improve the coke particle size while maintaining the coke strength, coal blend (pulverized coal and Sotsubusumi the addition amount of the caking additive for mixture) of a 2 to 10 wt%, preferably 5 to 10 mass%.

(Resolidification temperature of the mixture of binder and blended coal)
In the present invention, for the following reasons, the coal blend, a soft pitch or Ranaru caking material, a percentage of the coal blend, adding 2 to 10 wt%, mixed, blended coal (fine powder comprising the caking additive The resolidification temperature of the mixture of charcoal and coarse coal is set to 460 ° C. or higher.

  As shown in the relationship between the resolidification temperature of the blended coal (mixture of pulverized coal and coarse coal) and the effect of improving the coke particle size in FIG. 7, by increasing the resolidification temperature of the blended coal, In order to sufficiently reduce the amount of heat shrinkage in the direction perpendicular to the furnace wall surface and sufficiently improve the coke particle size, the resolidification temperature of the mixture of the pulverized coal and coarse coal containing the binder is 460 ° C. It is necessary to do it above.

  As shown in FIG. 7, the resolidification temperature of the mixture of the binder and the blended coal varies depending on the type (boiling point and softening point) of the binder to be added to the blended coal and the addition ratio with respect to the blended coal, and the boiling point of the binder. In addition, by adding a binder having a high softening point and increasing the addition ratio relative to the blended coal, the resolidification temperature of the mixture of the binder and the blended coal can be increased.

Therefore, in the present invention, in order to sufficiently improve the coke particle size by the addition of the caking additive, adjusting the composition of the soft pitch or Ranaru caking (boiling point and softening point of the caking), and // The resolidification temperature of the mixture of the pulverized coal and the coarse coal containing the binder by adjusting the amount of the binder added to the blended coal within the range of 2 to 10% by mass defined in the present invention. Is set to 460 ° C. or higher.

(Agglomeration of pulverized coal, rapid heating of coarse coal)
In an embodiment of the present invention, the mixture of pulverized coal and coarse coal at a temperature of 150 to 300 ° C. is obtained by drying the blended coal and further preheating, then classifying the coal into pulverized coal and coarse coal, and lump the pulverized coal. A mixture of the agglomerated coal and the coarse coal may be used after the coarse coal is rapidly heated while being agglomerated and agglomerated.

  In order to further preheat the blended coal after drying and classify it into pulverized coal and coarse coal, for example, it is effective to apply a method in which preheating and classification are simultaneously performed using a fluidized bed drying classifier. To preferred. In addition, as for the classification point when classifying into pulverized coal and coarse coal, pulverized coal of 0.5 mm or less causes dust generation, and caking components are oxidized by heating and cause strength reduction. The classification point is 0.5 mm.

  About pulverized coal of 0.5 mm or less, it is preferable to agglomerate using a granulator and a molding machine, and to improve the caking property and expansibility of pulverized coal. In the agglomeration of the pulverized coal, a caking agent such as tar may be usually added to improve the strength of the agglomerated product and the molding yield.

  In addition, the rapid heating treatment of the coarse coal is performed using, for example, an airflow tower type heater, and the coarse coal having a particle size of more than 0.5 mm is heated at a rate of heating of 3000 ° C./second and an ultimate temperature of 350 ° C. Heat rapidly. This rapid heating can improve the cohesiveness of coarse coal and improve coke strength.

In an embodiment of the present invention, and thus agglomerated been pulverized coal (KatamariNarusumi), a mixture of rapid heating treatment was coarse charcoal (Aratameshitsusumi), at a temperature of 150 to 300 ° C., soft the pitch or Ranaru caking material, a percentage of a mixture of pulverized coal and coarse coal, adding 2 to 10 wt%, were mixed, so that re-solidification temperature of the mixture containing the caking additive is 460 ° C. or higher In addition to the effect of increasing the coke particle size, the coke strength can be further increased.

(Non-slightly caking coal content)
In general, the resolidification temperature of non-slightly caking coal is less than 440 to 460 ° C., which is lower than that of caking coal (460 to 530 ° C.), so the amount of non-slightly caking coal in the blended coal increases. The re-solidification temperature of the blended coal decreases.

The effect of improving the coke particle size by adding the caking material consisting of the soft pitch of the present invention to the blended coal is also exhibited when the blending amount of the non-slightly caking coal in the blended coal is small, When the blending amount of the non-slightly caking coal in the blended coal is 30% by mass or more, a higher coke particle size improvement effect is exhibited.

  When the blending amount of the non-slightly caking coal in the blended coal exceeds 70% by mass, the coke strength decreases due to the increase in the blending amount of the non-slightly caking coal in the blended coal. It is preferable that the amount of non-slightly caking coal in the blended coal be 70% by mass or less.

  The effects of the present invention will be described below using examples. The present invention is not limited to only the embodiments of the following invention examples without departing from the object and technical idea of the present invention.

  FIG. 9 shows a coke manufacturing process applied in this embodiment.

  Coal 1 was dried by heating to 80 to 220 ° C. using fluidized bed drying classifier 2. As the binder 2, a tar heavy fraction having a component composition and a boiling point shown in Table 2 and a normal tar, a soft pitch having a softening point and a hydrogen / carbon atomic ratio shown in Table 3, and a petroleum pitch are used. Under the conditions shown in FIG. 1, a predetermined amount of the binder 5 was added to the coal 1 from the binder storage tank 6 and mixed.

  90 kg of coal was charged into a carbonization test furnace, and carbonized at a heating temperature of 1170 ° C. and a carbonization time of 13.5 to 18 hours to produce coke. The particle size of the obtained coke 6 was measured.

  Table 1 shows manufacturing conditions and test results. The coke particle size (MS) is measured according to the coke particle size test method described in JIS K 2151.

  Implementation No. shown in Table 1 In the inventive examples 1 to 8, the type and addition rate of the binder, the blended coal temperature when the binder is added, and the resolidification temperature of the blended coal including the binder satisfy the range defined by the present invention. Thus, while maintaining the coke strength DI: 85.8 or more, excellent coke having a target coke particle size of 48 mm or more is obtained.

  On the other hand, the implementation No. In Comparative Examples 7 to 130, any one of the types and addition ratios of the binder, the blended coal temperature when the binder is added, and the resolidification temperature of the blended coal including the binder is defined by the present invention. Since it was out of the range, the target coke particle size: 48 mm or more could not be achieved.

It is a figure explaining shrinkage | contraction of the coke lump in a coke oven carbonization chamber, and generation | occurrence | production of a longitudinal crack. It is a figure explaining the longitudinal crack and transverse crack of a coke lump in a coke oven carbonization chamber. It is a figure which shows the relationship between the furnace temperature of a coke oven, the preheating temperature of coal blend, and the particle size of coke. It is a figure which shows the change of the resolidification temperature with the case where a caking additive is not added to a combination charcoal, and the case where it adds. It is a figure which shows the relationship between the binder addition ratio at the time of caking additive (tar heavy fraction: component content whose boiling point is 300 degreeC or more = 83.2 mass%) addition, and coke shrinkage. It is a figure which shows the relationship between the binder addition ratio at the time of caking additive (tar heavy fraction: component content whose boiling point is 300 degreeC or more = 83.2 mass%) addition, and a coke particle size expansion effect. It is a figure which shows the relationship between the resolidification temperature of the mixture of a combination charcoal, and a caking additive, and the coke particle size expansion effect. It is a figure which shows the relationship between the kind of caking additive, an addition rate, and the coke particle size expansion effect. It is a figure which shows a coke manufacturing process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coal 2 Coal drying, preheating machine 3 Binder 4 Binder storage tank 5 Test dry distillation furnace 6 Coke

Claims (2)

Includes non-fine viscosity of coals 30 to 70 wt%, after the balance dry the coal blend consisting of caking coal was further preheated to a mixture of pulverized coal and coarse coal temperature of 150 to 300 ° C., soft beep Ji, a percentage of the mixture of the pulverized coal and the coarse coal, adding 2 to 10 wt%, it was mixed, re-solidification temperature of the mixture of the pulverized coal and the coarse coal containing the soft pitch is 460 ° C. or higher After that, a method for producing coke for blast furnace, which is charged into a coke oven and dry-distilled.   The mixture of pulverized coal and coarse coal at a temperature of 150 to 300 ° C. is obtained by drying the blended coal and further preheating, then classifying it into pulverized coal and coarse coal, and agglomerating the pulverized coal into agglomerated coal. The method for producing coke for a blast furnace according to claim 1, wherein the coarse coal is rapidly heated and then the agglomerated coal and the coarse coal are mixed.

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