JPH11246865A - Pretreatment method for coking coal and method for producing coke - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To practically use large amounts of non-coking coal and waste plastic as raw materials for producing blast furnace coke in order to prevent dust generation and carryover during coal charging. To provide a coking coal pretreatment method that makes it possible. SOLUTION: After pulverizing coking coal blended with non-fine caking coal,
It is dried until the moisture content becomes 6 wt% or less and continuously classified into pulverized coal and residual coarse coal. The classified pulverized coal is kneaded with a bituminous binder and mixed with the above residual coarse coal. In the pre-treatment of coking coal, a pre-treatment method of coking coal in which 5 wt% or less of waste plastic is blended into coking coal at an arbitrary stage after classification and before charging into a coke oven carbonization chamber, and A method for producing coke in which coking coal is charged into a coking chamber of a coke oven and carbonized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for pre-treating coking coal and a method for producing coke.
Prevents dust generation and carryover during coal transfer, improves coke quality, and makes it practically possible to use large amounts of non-coking coal and waste plastics as raw materials for manufacturing blast furnace coke. The present invention relates to a method for pre-treating coking coal.

[0002]

2. Description of the Related Art There is a worldwide shortage of high-quality caking coal (strong caking coal and weak caking coal) essential for producing coke for blast furnaces. Technical development of a coke manufacturing method with high coke strength using (non-coking coal) has been promoted. As one direction of this technology development, the dry coal charging method has already been developed and partially implemented. In this method, the moisture in the dry coal is usually set to 6% by weight or less, so that dust is remarkably generated in the transportation process of the charged coal and in charging the coke oven, and the working environment is deteriorated. In addition, the so-called carryover phenomenon, in which fine powder is entrained in the coke oven gas (COG) and tar generated during dry distillation in the coke oven and flows into the coke oven gas conduit, increases. The carryover coal powder has a problem that sludge content in the tar eventually increases, and furthermore, carbon trouble occurs in the coke oven.

For this reason, Japanese Unexamined Patent Publication No. 57-53587 discloses a dust generation mechanism and discloses a mechanism of 100 mesh (about 15 mesh).
0 μm) or less is separated from fine coal (coarse coal) having a larger particle size, and after pulverized coal is agglomerated, it is mixed with coarse coal again. I have. However, the carry-over powder when the coal is charged into the coking chamber includes powder having a size of 150 μm or more, which also causes a carbon trouble in the coking chamber and cannot sufficiently prevent sludge from being mixed in the tar. Japanese Patent Application Laid-Open No. 62-192486 also discloses that 100 μm
JP-A-57-5-5 discloses that after separating pulverized coal having the following particle size, a binder is added to the pulverized coal to form a pseudo-particle having a particle size of 100 μm or more by rolling or compression.
As in 3587, it is not sufficient as a countermeasure against carbon in the carbonization chamber and a countermeasure against sludge in tar.

Further, Japanese Patent Application Laid-Open No. 63-75089 discloses that in order to obtain a charged coal having a desired bulk density and to more effectively suppress the dust generation of the charged coal, it is necessary to reduce It discloses a method for producing charged coal in which the classification ratio of pulverized coal is 7% to 30% and the particle size of pseudo pulverized coal obtained by kneading a binder with the pulverized coal is 0.5 mm to 40 mm. However, in this method, the classification ratio of pulverized coal is 7
% To 30%, but the particle size and amount of pulverized coal that causes dusting and carryover vary depending on the composition of coal, so that only the classification ratio causes The amount cannot be specified.

[0005] By the way, with increasing awareness of environmental issues, there is an increasing number of attempts to utilize waste plastic more effectively than landfill or incineration. As one of them, it has been conventionally known to mix and treat waste plastic with coke oven coking coal. For example, JP-A-48-34901 and JP-A-59-120682 disclose that waste plastics are blended with coke raw coal and carbonized by dry distillation. In addition, Tokubo Sho 5
No. 1-562 and Japanese Patent Publication No. 51-562 disclose a method for producing a coke for melting using waste plastic as a partial substitute for the compounding pitch. In addition, 2-31
No. 756 discloses a method for carbonization of coal in which a polymer compound mainly composed of methylene bonds such as polymer waste is added in an amount of 0.8 to 0.001% by weight.

Furthermore, Japanese Patent Application Laid-Open No. 63-273694 discloses a method of enriching gas calories in a coke dry digester by introducing polymer waste into a moving bed of red hot coke. Japanese Patent Application Laid-Open No. 7-216361 discloses that waste plastics that have been pyrolyzed in advance are charged into a coke oven together with raw coal. However, none of these prior art references mentions a method of treating waste plastic in a dry coal operation for drying and classifying raw coal.

Japanese Patent Application Laid-Open No. Hei 9-241654 discloses a method for treating waste plastic in the case where the charged coal is pre-dried. That is, the charged coal obtained by mixing waste plastic with coking coal for coke production is dried to a water content of 2 to 6% by weight in a rotating inclined cylindrical dryer, and then charged into a coke oven and carbonized, or It is disclosed that after drying the coal blend for production to a moisture content of 2 to 6 wt%, waste plastics are mixed, charged into a coke oven and carbonized, and the like. However, even in this case, no mention is made of dust generation and carry-over prevention at the time of coal feeding caused by pulverized coal in the coking coal after drying, or measures against quality deterioration of coke by mixing waste plastic. .

[0008] In the conventional method for producing coke in which waste plastic is blended into coking coal for coke production, pretreatment of conventional coking coal is premised, and therefore, a dry coal operation process for coal, which is currently becoming mainstream, is premised. Is not applicable as it is. For example, when a fluidized bed dryer is used as a coal drying process, waste plastics are mixed into the coal input to the dryer because 200-400 ° C hot gas is directly used as a drying heat source. In this case, since the temperature of the hot gas is equal to or higher than the melting point of the general-purpose resin, there is a high possibility that the plastic is melted and fused, and there is a risk of adhesion, blockage trouble, and even ignition in the system.

Further, in the case where coal is classified by a fluidized bed dryer at the same time, or in the case where a classifier is combined with an indirect type dryer such as a steam tube dryer or a fluidized bed dryer, etc. If plastic is mixed, the specific gravity of plastic is much lower than that of coal, so that plastic scatters preferentially on the pulverized coal side to be classified. This may cause troubles in the process of classifying coal, and the plastic may be unevenly distributed in the classified pulverized coal when charged into the coke oven, which may have an adverse effect on coke quality. There is.

[0010] As described above, according to the conventionally proposed method, particularly low-coking coal (non-fine caking coal) is used as a part of high-quality caking coal (strong caking coal and weak caking coal). When the dry coal charging method is adopted instead, improvement is still required to prevent dust generation in the transporting process of the dry coal and to surely prevent the carryover phenomenon at the time of carbonization in the coke oven. In addition, there is a strong demand for the development of high-strength coke when blended into raw coal as an effective method of treating waste plastic.

[0011]

Under such circumstances, the present invention aims to provide high-quality caking coal (strong caking coal and weak caking coal), which lacks low caking coal (non-fine caking coal) worldwide. Prevention of dust generation in the coal transport process associated with coal drying and carry-over prevention in the case of coking coal when used together with waste plastics as industrial waste in coking coal. It is practically possible to use waste plastic as a raw material for coke for blast furnaces without compromising the quality of the system such as coke strength, etc. It is an object of the present invention to provide a method for pre-treating coking coal for coke production and a method for producing coke.

[0012]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and examined the particle size of pulverized coal serving as a dust source and a carryover source found in dry coal operation. Was. For dust sources, collect dust particles during the transportation process to the coke oven, and for carryover sources, collect scattered powder at the riser at the riser while charging coal into the coking chamber, and measure their particle size. The results of measuring the distribution are shown in FIG. 1 (dust source) and FIG. 2 (carry-over source), respectively. As is clear from FIGS. 1 and 2, most of the dust-producing particles are 0.1 mm or less (100 μm or less), particularly 70 μm or less (99.6%), but carry-over dust is 0.3 mm or less. (99%).

Further, as a result of further studies based on such findings, the present inventors have found that by drying the coal until the surface moisture is substantially eliminated, the pulverized coal can be completely separated from the coarse coal portion. Above, a binder such as tar is added to the pulverized coal classified at a limit classification point of the fine powder within a range of 0.2 to 0.4 mm and kneaded, and the kneaded material is briquetted to a residual coarse coal portion. By mixing
It has previously been found that the prevention of dust generation during the transportation process associated with coal drying and the almost complete prevention of the carryover phenomenon during the charging of dry coal into the carbonization chamber or during the carbonization are simultaneously achieved (Japanese Patent Application No. Hei 9 (1994)). -244277).

The inventors of the present invention have conducted various studies in order to further solve the problem of adding waste plastics in the operation of dry coal of raw coal containing non-coking coal. Assuming the charcoal process, by mixing waste plastic in the post-process of the classifier, adhesion in the system, blockage troubles, ignition, etc. are prevented, and troubles occur in the classification coal treatment process. Waste plastics as industrial waste can be treated without increasing the coke quality such as coke strength, and the coke oven gas (COG), a by-product of coke production, can be increased and recovered. Thus, the present inventors have found that waste plastics can be effectively used, and have completed the present invention.

That is, in the method for pre-treating coking coking coal of the present invention, coking coal blended so as to include at least a part of non-coking coal is pulverized and then dried to a water content of 6 wt% or less. During or immediately after drying, the coal is continuously classified into pulverized coal and residual coarse coal, and the classified pulverized coal is kneaded with a bituminous binder and then pre-treated with the above-described raw coal to be mixed with the residual coarse coal. , Wherein 5 wt% or less of waste plastic is blended into raw coal at an optional stage after the classification treatment and before charging into the coke oven carbonization chamber.

According to the present invention, after pulverizing the raw coal,
By drying until the water content becomes 6 wt% or less and continuously classifying the coal into fine coal and residual coarse coal, the fine coal, which is a source of dust generation and carryover, is easily separated from the coarse particles. Then, a bituminous binder is added to the pulverized coal and the mixture is kneaded, whereby the pulverized coal is agglomerated with the binder to form particles, and the coke quality is improved despite the increased use of non-coking coal. Furthermore, since waste plastic is added at the stage after the classification process, the temperature of the raw coal at that time is at most several tens of degrees, which is significantly lower than the softening temperature and melting temperature of the waste plastic, and the subsequent handling of the raw coal Dry coal operation becomes possible without causing any trouble. Further, in the present invention, even if waste plastic is further added to the raw coal containing a large amount of non-coking coal, reforming of the raw coal with tar or the like as a binder is more effective to prevent a decrease in coke quality. In addition to this, a coke oven gas (COG), which is a by-product of coke production, can be increased and recovered, and a dry coal operation method that can effectively utilize waste plastics can be realized.

Particularly preferred embodiments of the present invention include the following requirements. (1) It is more preferable to dry the raw coal until the moisture content is 6 wt% or less, particularly until the surface moisture substantially disappears. Thereby, even when the fine powder portion is an aggregate of pseudo particles, the fine coal is easily disintegrated and the pulverized coal is completely separated from the coarse particle portion. (2) Classification is preferably performed by adjusting the boundary classification point in the range of 0.2 to 0.4 mm. This makes it possible to completely separate the pulverized coal serving as the dust generation source and the carry-over source shown in FIGS. 1 and 2 and thoroughly prevent the above-mentioned dust generation and carry-over by kneading the bituminous material with the binder.

(3) The pulverized coal is preferably kneaded with a binder, briquetted at a linear pressure of 0.5 to 2.0 t / cm, and then mixed with the residual coarse coal. This is achieved by briquetting pulverized coal, which is a source of dust generation and carry-over, with a forming roll, to prevent crushing during the transport process and charging process on the belt conveyor, and to prevent the above-mentioned dust generation and carry-over. You can be assured.
In addition, at the time of charging the carbonization chamber by mixing with the coarse particle portion, the gap between the briquettes is filled with the coarse particle portion to maximize the charging bulk density, thereby improving the obtained coke strength, etc. It has a function and effect. (4) When adding the waste plastic, pulverized coal (including briquettes) kneaded with a binder is mixed at the same time or after mixing with the residual coarse coal, but the cost required for addition is low. Is most realistic and preferable.

Further, the method for producing coke of the present invention is characterized in that the raw coal treated by the above-mentioned pretreatment method is charged into a coking chamber of a coke oven and carbonized. in this case,
The pretreated raw coal is stored in a coke oven charging coal tank, then charged into a coke carbonization chamber, and subjected to dry distillation under normal temperature conditions.

Hereinafter, the components of the present invention will be described in detail. First, as raw coal, non-fine caking coal, which is easier to obtain and cheaper than hard caking coal, is used in combination with hard caking coal. Non-slightly caking coal does not correspond to high-quality caking coal (strong caking coal and weak caking coal), and can be used alone to produce low-grade coke that is not suitable for blast furnace coke. Low coal (or low caking) coal. There is no generalized definition of such non-coking coal in the coke industry, including the steel industry. Therefore if Shimese the result of the present inventors have analyzed the various non-fine viscosity coals, in relation to coal degree R _o and maximum fluidity degree MF (JIS M8801) is, R _o
≦ 1.0, and MF (logDDPM) range of ≦ 3.0 (although DDPM stands for Dial Deviation per Minute) is intended to fall within the scope of, or coal degree R _o and the total expansion ratio TD ( JI
S M8801), R _o ≦ 1.0 and TD ≦ 50
Can be roughly defined as falling under the range of, but is not limited to this definition, and even outside this range, the above-described low coking (or low caking) coal is used. If so, it is included in the non-caking coal of the present invention.

In the conventional dry charcoal charging method, the blending amount of the non-coking coal in the raw coal is generally in the range of 20 to 30% by weight or less, and at most about 40% by weight. It is. In the present invention, the lower limit of the non-fine caking coal in the raw coal is not particularly limited, but it can be usually used in the range of 30% by weight or more, particularly preferably in the range of 40 to 60% by weight. is there. However, when the amount of the non-coking coal is increased by 60% by weight or more, there is no problem from the viewpoint of dust generation, but the ash content and the sulfur content are excessive, and the strength of the blast furnace coke tends to be insufficient.

The raw coal is first blended for each group of coal and then crushed for each group or collectively. Also,
After being ground to a predetermined particle size for each brand of raw coal such as high-quality caking coal and non-fine caking coal, it can be blended. Alternatively, a method of grinding after yard blending may be employed. In coke production, grinding of coking coal is indispensable,
Pulverization in the post-classification step generates fine powder again, so that the object of the present invention cannot be achieved, and drying and classification after pulverization are essential.

In this pulverizing step, the target particle size is changed by pulverizing the non-finely caking coal and the strongly caking coal to pulverize the non-micro caking coal,
It is best to roughen the strongly caking coal. Non-slightly caking coal is harder and has a coarser grain size than harder caking coal, whereas non-slightly caking coal has a lower caking property, so tar modification is more effective for large-scale use. is there. Specifically, the particle size of 3 mm or less is set to 50 to 70% by weight for good quality caking coal, while the particle size of 3 mm or less is set to 80 to 9 for non-fine caking coal.
Preferably it is 5% by weight. In addition, when blending good-quality caking coal and non-fine caking coal after pulverizing the coal for each group, the non-fine caking coal is pulverized into one so that only the non-fine caking coal can be pulverized and strengthened. It is preferred to gather in a line of machines. By finely pulverizing the non-coking coal, the proportion of non-coking coal in the dried and classified pulverized coal increases, and the proportion of non-coking coal mixed with tar increases. Therefore,
During dry distillation in a coke oven carbonization chamber, non-slightly caking coal has a greater effect of reforming with tar. The strength will be improved.

After pulverizing the raw coal blended so as to include at least a part of the non-coking coal, the content of water is reduced to 6 wt.
%, Preferably 3% by weight or less as total moisture, more preferably until the surface moisture is substantially eliminated. Here, "substantially no surface moisture" refers to a state in which the surface moisture is 0.5% by weight or less, and drying is optimally performed until the surface moisture is eliminated (surface moisture ≒ 0%). Here, the surface moisture refers to a value obtained by subtracting the contained moisture (JIS M 8803) from the total moisture (JIS M 8811). Further, in actual operation, the surface moisture may be directly measured by a commonly used infrared moisture meter. In this case, it is preferable to dry the total moisture to 3% by weight or less, more preferably to about 2% by weight or less. It is best to dry until the surface moisture is substantially eliminated.If a large amount of surface moisture remains, the fine powder tends to be unable to be sufficiently separated from the coarse-grained portion. By doing so, the effect of preventing dust generation by briquetting becomes insufficient.

For drying, any dryer can be used. For example, in addition to a direct heating type fluidized bed dryer, an indirect heating type dryer such as a rotating inclined cylindrical steam tube dryer can also be used. . In particular, when a fluidized bed dryer is used, hot air is blown from the floor surface and is directly contacted with the coking coal, so that the coking coal can be dried while being fluidized. In the case of this drier, in the case of wet coal before drying, pulverized coal forms pseudo particles due to moisture and is difficult to separate, but the raw coal is stirred in the fluidized bed and the particles are rubbed. Due to the washing effect, the fines are more easily separated. In addition, along with the dryer, a preliminary drying step is provided in the preceding stage,
It may be pre-dried. The dryer may be any of a system in which a pulverized coal classification function is integrally provided at an upper discharge port, and a system in which a pulverized coal classifier is separately provided in a dust collector or the like at a later stage of the dryer.

By using such a dryer and a classifier, the raw coal is classified into a pulverized coal portion and a coarse coal portion during or immediately after the drying step. In particular, a dryer integrally provided with a coal classification function is preferable because a part of the fine powder can be classified by an air current that is a heat source for drying. In this case, the pulverized coal portion continuously classified from the coarse coal portion by adjusting the passage speed of the airflow from the upper space of the dryer to the vicinity of the discharge is discharged together with the airflow and appropriately collected by a dust collector such as a bag filter. Dust and collect. In the present invention, up to this stage, waste plastic is not blended, and only raw coal is treated, so that raw coal can be reliably dried and classified into coarse-grained coal and pulverized coal. There is no problem such as the adhesion of the waste plastic melted.

In the drying step or after the drying, when the raw coal is classified into a pulverized coal portion and a coarse coal portion, the boundary classification point is 0.2 to 0.4 mm, preferably 0.2 to 0.4 mm.
It is preferable to adjust to 3 mm. By drying until the surface moisture of the coal is substantially eliminated (surface moisture ≒ 0%), and by classifying the fine powder with such a classification point, dust generation during coal transportation and carry-over during charging in the carbonization chamber are performed. Sources can be almost completely eliminated. When the boundary classification point is less than 0.2 mm, the fine powder which causes dust generation and carryover tends to be transported together with the coarse coal. Further, even if the classification point exceeds 0.4 mm, the effect of increasing and decreasing dust generation and carryover is small, and the running cost for briquetting tends to increase.

A bituminous binder is added to the classified pulverized coal in a molten state. Tar, heavy oil, pitches and the like can be used as a binder for bituminous substances, and particularly, crude tar recovered from a coke oven can be used as it is. As such a coarse tar, a sludge which is settled in a decanter may be used in combination. Also, the tar condensed from the coke oven riser to the suction main, that is, the tar having a relatively large amount of heavy tar is separated and collected, and the separated and collected tar is kneaded with pulverized coal as a binder to form coagulated particles. When used for briquetting, etc., it can contribute to the improvement of coke strength. In addition, heavy oil and pitches may be added as a binder together with tar.

The addition of the binder of the bituminous substance to the classified pulverized coal is not limited well using an arbitrary mixing stirrer. In particular, a pin type or paddle type kneader is suitably used for uniform kneading. The amount of the binder to be added to the pulverized coal is 6 to 15% by weight, preferably 8 to 12% by weight. In the present invention, in particular, in the case of drying until the surface moisture is substantially eliminated, it is preferable that the kneaded product of the pulverized coal and the binder is further pressure-molded into briquettes by a roll molding machine. Briquetting in this way is because pulverized coal in dry coal may cause dusting and carryover.In addition to simply kneading and kneading a binder, briquetting was performed by pressure molding. This prevents the pulverized coal from collapsing again during the transportation process to the coke oven, thereby making it possible to ensure the prevention of the re-generation of pulverized coal which causes dust and carryover.

The shape of the briquette in this case is not particularly limited as long as it is formed into a shape such as a spherical shape, a square shape, and an elliptical shape. For example, long side 50-70 mm, short side 3
A square briquette having a thickness of about 0 to 50 mm and a thickness of about 30 mm may be used. The briquette molding pressure is linear pressure = 0.5.
It is preferable to set the range to 2.0 t / cm. When the linear pressure is less than 0.5 t / cm, it is insufficient to prevent the re-generation of pulverized coal due to briquette collapse in the transportation process. There is almost no improvement in the effect of preventing re-generation, which is wasteful in energy.

The pulverized coal kneaded with a bituminous binder is
If desired, briquettes can be formed and uniformly mixed with the dry coarse coal coming out of the drying / classifying process to obtain raw coal for coke production. In the present invention, in the pre-treatment of the coking coal by drying and classification, 5 wt% is preferably used at any stage after the drying and classification treatment and before charging into the coke oven carbonization chamber.
The following is a pretreatment method for coking coking coal which has the greatest feature in blending waste plastic of 2 wt% or less into coking coal.

In this case, as long as the waste plastic has been subjected to the drying and classification treatment, even in the subsequent pulverized coal treatment stage,
Alternatively, it can be blended even during the coarse coal transfer step.
For example, waste plastic is added to coarse-grained coal and mixed with pulverized coal (or briquette molded product) kneaded with a binder of bituminous material separately to make charged coal, or a binder of bituminous material is added to pulverized coal. When adding and kneading, waste plastics may be added at the same time to obtain coking coal. However, most practically, it is abandoned when pulverized coal (or briquettes) in which bituminous binders are uniformly kneaded is mixed with coarse coal, or during the transfer of a belt conveyor to a coke oven charging coal tank after mixing. It is most convenient to add a plastic. The coke-producing coking coal pretreated in this manner is charged into a coking chamber of a coke oven from a charging coal tank by a charcoal truck and carbonized by coking. In this case, the carbonization conditions are not particularly limited.

Examples of the waste plastic mixed in the present invention include films and sheets, machine and equipment parts, pipes and joints, foam products, daily necessities and miscellaneous goods, building materials, containers, synthetic leather, plates, reinforced products (FRP), and the like. Waste plastics that have been discarded after being used for each of the above-mentioned applications, and in particular, are difficult to recycle, and have been landfilled or incinerated. At present, it includes both industrial waste and general waste disposed of by general consumers. However, as properties of waste plastic, chlorine (Cl), sulfur (S)
And that the content of trace metals and other is less than or equal to the content in the coke coal, coke quality, by-product properties, from the viewpoint of avoiding adverse effects on the coke oven brick, for example, polyethylene, polypropylene And other molded products mainly composed of polyolefins.

It is preferable that the waste plastic is appropriately crushed to a predetermined size and particle size, or subjected to a heating and molding process so as to be adjusted to a certain extent to the particle size of the raw coal. For example, it is preferable that the maximum particle size (top size) of the blended coal for coke production is equal to or less than the maximum particle size, that is, about 10 to 15 mm. This is because if the particle size of the waste plastic is significantly different from the particle size of the coal, the overall particle size distribution changes upon charging the coke oven, and the bulk density of the charge is likely to change. This is because it may affect the crack growth of the coke mass at the time of carbonization, and may also affect the coke strength.

As a specific material of such waste plastic, not only a thermosetting resin or a thermoplastic resin, but also a resin composite material such as a glass fiber reinforced resin (FRP) may be used. That is, phenol resin, amino resin, diallyl phthalate resin, epoxy resin, polyester resin, silicone resin, polyurethane resin, polyimide, polyethylene, polypropylene, vinyl acetate resin, polystyrene, acrylonitrile-butadiene-styrene resin (ABS resin), acrylonitrile-styrene resin (AS resin), polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl formal, methacrylic resin, fluororesin, polycarbonate, polyacetal,
Nylon, polyamide, polyethylene terephthalate (PET), polybutylene terephthalate (PBT),
Polyphenylene ether (PPE), polyphenylene sulfide (PPS), polysulfone, polyether sulfone, polyether ether ketone, polyarylate, polyester, cellulose acetate and the like, and mixtures thereof are not particularly limited.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below with reference to the overall process flow. The present invention is shown in FIG.
(1) to (9) below. (1) Raw Coal Adjustment Step A non-fine caking coal, which is more easily available and cheaper than good caking coal, is used in combination with good caking coal. In the present invention, the amount of non-fine caking coal in the raw coal is preferably 30% by weight or more, and particularly preferably 40 to 60% by weight. (2) Coking Process of Coking Coking Coking coal is first adjusted for each type of coal (group) and for each yard, and mixed at a predetermined ratio for each group or collectively. Alternatively, it can be blended after grinding for each brand of raw coal.

(3) Pulverizing Step The raw coal may be pulverized by any method. Preferably, the pulverization is performed by changing the target particle size between non-fine caking coal and good-quality caking coal. In this case, it is optimal to make the non-fine caking coal finer and the good quality caking coal coarse. Specifically, it is preferable to set the particle size of 3 mm or less to 50 to 70% by weight for good quality caking coal, and to set the particle size of 3 mm or less to 80 to 95% by weight for non-fine caking coal.

(4) Drying / Classification Step Coking coal usually contains about 10% by weight of water even after pulverization, and this is reduced to 6% by weight or less by a fluidized bed drier by hot air of combustion gas, preferably. Dry until the surface moisture is substantially eliminated (surface moisture ≒ 0%). In this case, the total moisture content is dried to less than 3% by weight, preferably to about 2% by weight. It is preferable that the fluidized bed drier has a function of integrally classifying pulverized coal at the upper outlet. The boundary classification point when classifying into pulverized coal and coarse coal is 0.2 to
It is important to adjust it to 0.4 mm, preferably in the range of 0.2-0.3 mm.

(5) Binder (tar) addition step Bituminous substances such as tar are added in a molten state as a binder to the classified pulverized coal. (6) Kneading Step The addition of the binder of the bituminous substance to the classified pulverized coal is not limited well using an arbitrary mixing stirrer. In particular, a pin type or paddle type kneader is suitably used for uniform kneading. The amount of binder added to pulverized coal is 8 to 1
2% by weight is preferred. (7) Molding Step The kneaded product of the pulverized coal and the binder is further subjected to pressure molding into briquettes by a roll molding machine, if desired. In this case, the briquette molding pressure is preferably in the range of linear pressure = 0.5 to 2.0 t / cm.

(8) Step of Adjusting Coal Charged into Coke Oven Pulverized coal (or a briquetted molded product thereof) kneaded with a binder is dried coarse coal obtained from the drying / classifying step and, in some cases, It is mixed with the waste plastic of (9) on a belt conveyor or the like to adjust the charged coal. After that, it is appropriately stored in a coke oven charging coal tank and then charged into a carbonization chamber of a coke oven. In this case, as described above, the waste plastic is mixed at the stage after the drying / classifying step. With respect to the charging conditions of the coking oven in the coking oven, for example, if the packing density of the charged coal is relatively high, such as 0.8 to 0.85 t / m ³ , the coal is charged during the carbonization in the coking chamber. In combination with the modification of the non-coking coal, the strength of the produced coke is improved.

(9) Waste Plastic Mixing Step The waste plastic can be mixed during the pulverized coal treatment step or the coarse coal transfer step as long as it has been dried and classified. However, it is simple and most preferable to mix the waste plastic when or after mixing the pulverized coal pressed into briquettes in the pulverized coal treatment step with the coarse coal in the step (8). It is most preferable that the blending ratio of the waste plastic is 5% by weight or less, particularly preferably 2% by weight or less, without remarkable decrease in coke strength. The size of waste plastic and its processed products is determined by the maximum particle size (top size) of coking coal for coke production.
It is preferably equal to or less than, that is, about 10 to 15 mm.

[0042]

EXAMPLES Examples of the present invention and comparative examples will be described below, but it goes without saying that the present invention is not limited to these examples.

Example 1 Pretreatment of raw coal for coke production was carried out as follows. Non-fine-caking coal (coal degree of R _o: 0.69, maximum fluidity MF (logDDPM): 2.06, the total expansion rate TD: 2
Raw material coal for coke production (9.0% moisture) containing 45% by weight of 9) and 55% by weight of good-quality caking coal was crushed to a particle size of 3 m.
m or less to 85%, and flash-dried using a test dryer until the total moisture content of the coal becomes 2% by weight (surface moisture = 0%). The mixture was classified into fine coal and coarse coal using a 3 mm sieve. Three types of coarse tar (6, 8, 1) were added to the classified pulverized coal.
0% by weight) and kneaded by addition and kneading to form aggregated particles.
Furthermore, with a molding machine at a linear pressure of 1.0 t / cm and a long side of 65 m
m, short side 42 mm, thickness 28 mm, and volume of 56 cc. After being subjected to 10 shutter tests for dropping from a height of 2 m, the sieves were 0.3 mm or less and 0.1 mm or less. The proportion was measured. The result (Comparative Example 1)
Table 1 shows the latter (briquetting) as Example 1. For reference, when the briquette molding is added, the same sieving ratio before the shutter test is also shown.

[0044]

[Table 1]

As is clear from Table 1, the surface moisture = 0%
In the case where the pulverized coal is tar-kneaded, pulverized coal having a tar addition rate of 10% is 3.3% by weight and pulverized coal having a diameter of 0.3mm or less is 53.7%.
% By weight. On the other hand, when briquette molding was added, pulverized coal having a tar addition rate of 10% and 0.1 mm or less was also 1.06% by weight, as is clear from Table 1.
Pulverized coal having a size of 0.3 mm or less is extremely low at 3.81% by weight. Therefore, the amount of fine powder generated in the shutter test assuming the transfer process on the belt conveyor is extremely smaller in the case where briquette molding is added than in the case where only tar kneading is performed, and the coal mixture before drying (moisture 9 wt%) From the fact that it is equal to or less than the state, it can be foreseen that the effect of preventing dust generation in the actual device and the effect of suppressing carryover will be exhibited.

EXAMPLE 2 Coking coal (moisture 9.0%) containing 57% by weight of the same non-coking coal as used in Example 1 and 43% by weight of good-quality caking coal was used. 85% for crushed particle size of 3mm or less
And crushed. Using a test dryer, this raw coal is flash-dried until the total moisture content of the coal becomes 2% by weight (surface moisture = 0%), and then it is pulverized with pulverized coal using a sieve having a boundary classification point of 0.3 mm. Classified into granular charcoal. The pulverized coal classification ratio at the time of classification in this manner was about 30%. After adding and mixing 10 wt% of coarse tar to the classified pulverized coal, the molding machine uses a linear pressure of 1 t / cm and a long side of 65 mm and a short side of 4 mm.
It was molded into briquettes having a size of 2 mm, a thickness of 28 mm, and a volume of 56 cc. The briquette molded product of this pulverized coal was mixed with coarse coal to obtain charged coal.

To the mixture of coarse coal and briquette, molded products mainly composed of polyethylene and polypropylene films were added as waste plastics at a ratio of 1, 2, 3, 4 and 5% by weight. The properties of this waste plastic are mainly carbon (C) and hydrogen (H), and chlorine (Cl) is 0.1%.
% Or less, and the molded product has a cylindrical shape (diameter 8 mmφ ×
Length 10-20 mm). At this time, no dust was generated at all during the briquette transporting step, the mixing step with the coarse coal, and the charging into the electric furnace. For carbonization, this charged coal is converted into an electric furnace (450 mm wide, 500 mm high, 640 m long).
m) and the coke temperature is raised to 1050 ° C,
The carbonization was completed. Drum strength DI of the obtained coke
Table 2 shows the results of measuring the strength CSR after the reaction with (150/15). Further, in the case where no binder was added to the classified pulverized coal, under the same conditions as in the above example, the mixture was mixed with coarse coal, and waste plastic was added at a ratio of 1% by weight and 2% by weight. Coke was obtained by carbonization in an electric furnace.
The results of measuring the drum strength DI (150/15) and the post-reaction strength CSR of the obtained coke are shown in Table 2.

[0048]

[Table 2]

From the results shown in Table 2, the coke strength was as low as the cold strength (DI) even though the non-sintered coal was 57% by weight and the waste plastic was blended at 5% by weight or less.
₅₀ ¹⁵⁰ ) and post-reaction strength (CSR) both show high values without substantial adverse effects, indicating that coke having excellent properties can be obtained. It is apparent that the coke strength is significantly improved when the binder is kneaded to form a briquette as compared with the case where the binder is not added.

The raw coal for coke production (water content of 9.0%) used in Example 2 was replaced with a total water content of coal of 5%.
After indirect drying until the weight of the pulverized coal is reduced, the crude coal is classified into pulverized coal and coarse coal in the same manner, coarse tar is added to the classified pulverized coal, mixed with coarse coal without briquetting, and waste plastic Was confirmed by using the same electric furnace. Also in this case, it has been confirmed that coke having excellent properties is obtained, dust generation and carryover are prevented, and there is no problem such as adhesion in the system despite addition of waste plastic. In addition, as a result of these examples, the coke oven gas (COG) generation yield and the like also tended to increase in accordance with the increase in the amount of waste plastic added, and the calorific value of the generated gas also increased, resulting in higher calorie. Has been confirmed. Therefore, cracks hardly occur even during dry distillation in a coke oven, and this is a practically suitable raw material pretreatment method as blast furnace coke.

[0051]

According to the present invention, the drying process of coal has been accompanied by not a few problems of dust generation and carry-over at the time of transporting the dried coal and charging it into the coking chamber. By kneading the binder with the pulverized coal that causes dust and the like, the same operation level as wet coal can be achieved. In addition, by pulverizing pulverized coal into a molded product as desired, the possibility of re-collapse during the transportation process to the coke oven can be minimized, and dust generation and carryover can be more reliably prevented. The quality of the coke for blast furnaces, especially the coke strength, can be further improved in combination with the fact that the density of the charged coal in the furnace can be increased. Therefore, the present invention can prevent dust generation in the transportation process associated with drying even when a large amount of low-coking coal (non-coking coal) is blended with high-quality coking coal, which is in short supply worldwide. In addition, the measures for preventing carryover during charging of dry coal into the carbonization chamber or during dry distillation can be made thorough, and the bulk density of charging dry coal can be maximized to further improve coke strength.

Further, according to the present invention, the problem of adding waste plastic in the operation of dry coal, that is, adhesion, clogging trouble, ignition and the like in the system is prevented, and the plastic mixed with coal is coke-free. It is pyrolyzed at the same time as coal carbonization proceeds in the furnace, contributing to increased generation of coke oven gas and increased recovery of light oil and tar. Further, plastics are melted and thermally decomposed in the softening and melting temperature range of coal, so that the fluidity and expandability (caking property) of the blended coal are improved, leading to an improvement in coke strength. In general, the coal drying process is aimed at increasing the use of inferior coal with low cohesion.However, by applying a plastic compound to the dry coal process, it is possible to increase the use of inferior coal or use less inferior coal. Becomes

Therefore, according to the present invention, it is possible to practically use a large amount of inferior coal, that is, non-coking coal, while effectively satisfying the quality as blast furnace coke, and to effectively utilize coal resources. The present invention is a very useful invention in terms of construction, which leads to the effective use of waste plastics that have been landfilled or incinerated as materials for coke production.

[Brief description of the drawings]

FIG. 1 shows the particle size distribution of pulverized coal serving as a dust source.

FIG. 2 shows the particle size distribution of pulverized coal that has become a carryover source.

FIG. 3 is an overall flow sheet of the pretreatment method of coking coal for coke production of the present invention.

Claims (6)

[Claims] Claims 1. A pulverized raw coal blended so as to contain at least a part of non-coking coal is dried until the water content becomes 6% by weight or less. After continuously classifying into fine coal and kneading bituminous binder into the classified pulverized coal, in the pretreatment of the raw coal mixed with the above residual coarse coal, after classification, it is transferred to the coke oven carbonization chamber. A pretreatment method for coking coking coal, characterized in that 5 wt% or less of waste plastic is mixed into coking coal at an arbitrary stage before charging. 2. The method for pre-treating coking coking coal according to claim 1, wherein the coking coal is dried until the surface moisture is substantially eliminated. 3. Classification is performed by setting a boundary classification point to 0.2 to 0.4 m.
2. The pretreatment method for coking coking coal according to claim 1, wherein the method is performed by adjusting the range to m. 4. The raw coal for coke according to claim 1, wherein the pulverized coal is kneaded with a binder, briquetted at a linear pressure of 0.5 to 2.0 t / cm, and then mixed with residual coarse coal. Processing method. 5. The raw coal for coke according to claim 1, wherein the waste plastic is blended when pulverized coal (including briquettes) kneaded with a binder is mixed with the residual coarse coal or after mixing. Pre-processing method. 6. A process for producing coke, comprising charging raw coal treated by the pretreatment method according to any one of claims 1 to 5 into a carbonization chamber of a coke oven and dry-distilling it. Method.