JP6877886B2 - Manufacturing method of binder for briquette - Google Patents

Description

The present invention relates to a binder for briquette and a method for producing the same. More specifically, the present invention relates to a method for producing a binder for producing briquette, which is made from coal tar and tar slag produced as by-products from a coke oven when coke is produced.

Coke for iron making is produced by blending crushed coal (powdered coal) such as coking coal and non-slightly coking coal, charging it into a coke oven, and carbonizing it at a high temperature in the coke oven. It is desirable that coke has high strength because pulverization in the blast furnace during iron making deteriorates the air permeability in the blast furnace. In order to increase the strength of coke, it is necessary to contain a certain percentage or more of caking coal in the coke raw material. However, it has become difficult to obtain caking coal in recent years due to its limited reserves and production areas.

On the other hand, slightly caking coal and non-caking coal (hereinafter collectively referred to as "non-slightly caking coal"), which are inferior in caking property to caking coal, are compared with caking coal. It has abundant reserves and can be obtained at low cost. For this reason, studies have been conducted on adding more non-slightly caking coal while maintaining the strength of coke. Above all, the method of using briquette as a raw material for coke not only makes it possible to use more non-slightly caking coal, but also expands the briquette during the coke manufacturing process to compact the surrounding pulverized coal portion. This is useful because it is a method that can increase the coke strength.

In the production of such briquette for coke production, it is difficult to maintain the shape of the briquette even if only pulverized coal such as caking coal or non-slightly caking coal is molded. For this reason, briquette is generally produced by molding a mixture of a component called a binder (binder) together with pulverized coal. Usually, as the binder used for the molded coal for coke production, coal pitch, asphalt, road tar and the like (see Patent Document 1), tar, heavy oil, pitches and the like (see Patent Documents 2 and 3), and the like. Coal tar, asphalt, and bitumen (see Patent Document 4) such as pitch obtained by distilling or heavytening tar or asphalt are used.

On the other hand, when coal is carbonized to produce coke, a large amount of coke oven gas is produced as a by-product. The main components of coke oven gas are hydrogen, methane, carbon monoxide, carbon dioxide, etc. In addition to these main components, tar content, ammonia, hydrogen sulfide, hydrocarbon gas other than methane, crude light oil component, hydrogen cyanide , And many other ingredients are included.
The coke oven gas is refined by a gas refining facility and used as an energy source, and when the coke oven gas is cooled in this gas refining facility, a large amount of solid-liquid mixture is generated. In a tar decanter, this solid-liquid mixture is statically separated in a tar slag containing water, tar, tar and solids, and separated and recovered.

Of these, tar, which is a liquid substance, is effectively used as coal tar for various purposes by undergoing a process such as distillation. Specifically, it is used as a binder component in the above-mentioned briquette or as a material for a carbon electrode by coking. Tar slag, which is a residue obtained by recovering water and tar, is a semi-solid substance, which is used as a raw material for coke for iron making by adding it to coking coal, and is also used as a fuel by finely pulverizing it (Patent Document). 5).

Japanese Unexamined Patent Publication No. 57-80480 Japanese Unexamined Patent Publication No. 10-130653 JP-A-2007-284557 Japanese Unexamined Patent Publication No. 2011-26468 Japanese Unexamined Patent Publication No. 2010-209165

As described above, tar and tar slag produced as a by-product in the production of coke are used for different purposes. However, while tar is actively used as a raw material for binders and electrode materials, tar slag is treated as industrial waste and is mainly used as a raw material for coke for iron making by adding it to coking coal. It was just.
In the tar decanter described above, the solid-liquid mixture obtained by cooling the coke oven gas is layer-separated over time to recover tar and tar slag, but in order to recover more tar components, static separation is used. It took a long time. In addition, if more tar is recovered, the amount of solid content of tar residue, which is a residue, will increase, so it will be necessary to use a scraper to scoop up the tar from the bottom of the tar decanter, which will impose a load on equipment operation. was there.
Furthermore, since the composition of the tar slag after the tar is recovered is not stable, there is a problem in quality uniformity when the tar slag is added to the coking coal.

As described above, conventionally, the effective use of tar slag as a raw material has not been sufficiently studied. Therefore, it has not been known what kind of characteristic tar slag can be effectively used as a raw material for what kind of use.
An object of the present invention is to effectively use tar slag, which has conventionally been mainly used as industrial waste or fuel, as a binder for briquette. More specifically, it is an object of the present invention to use tar slag as a binder suitable for briquette production.
Another object of the present invention is to recover tar slag, which is subject to a load on equipment operation when recovering from a tar decanter, without applying a load.

As a result of diligent studies to solve the above problems, the present inventors have dared to take tar against the general common wisdom that the utility value of tar slag as a residue is extremely low because more tar with high utility value has been recovered in the past. We have found that tar slag can also be effectively used as a binder for briquette if a part of the tar component is recovered as tar slag, and the present invention has been reached.

That is, the gist of the present invention lies in the following [1] to [9].
[1] A binder for briquette made of a mixture of tar and tar slag, which has a viscosity of 330 mPa · s or less at 70 ° C. and a weight loss (A) of 87 when heated from room temperature to 900 ° C. Binder for briquette that is less than%.
[2] The binder for briquette according to [1], wherein the weight loss (B) when heated from room temperature to 400 ° C. is 44 to 55%.
[3] The value ((A) / (B)) obtained by dividing the weight loss amount (A) when heated from room temperature to 900 ° C. by the weight loss amount (B) when heating from room temperature to 400 ° C. is 1. The binder for briquette according to [1] or [2], which is .40 to 1.60.
[4] The binder for briquette according to any one of [1] to [3], wherein the content ratio of the solid content having a particle size of 3 mm or less is 5 to 30% by weight.
[5] Tar and tar slag are recovered from the solid-liquid component produced as a by-product when coal is carbonized to produce coke, and by mixing these, the viscosity at 70 ° C. is 330 mPa · s or less, and the viscosity is at room temperature. A method for producing a binder for briquette, characterized in that the amount of weight loss (A) when heated to 900 ° C. is 87% or less.
[6] The method for producing a binder for briquette according to [5], wherein the weight loss (B) when heated from room temperature to 400 ° C. is 44 to 55%.
[7] The value ((A) / (B)) obtained by dividing the weight loss amount (A) when heated from room temperature to 900 ° C. by the weight loss amount (B) when heating from room temperature to 400 ° C. is 1. .40. The method for producing a binder for molded charcoal according to [5] or [6], which is obtained as one of 40 to 1.60.
[8] The method for producing a binder for briquette according to any one of [5] to [7], wherein tar and tar slag are separated by a tar decanter.
[9] A method for producing briquette for producing coke containing pulverized coal and a binder, wherein the binder for producing coke according to any one of [1] to [4] is used as the binder for producing coke. Method.

According to the present invention, it is possible to provide a method for effectively utilizing tar slag, which has conventionally been mainly used as industrial waste or fuel, as a binder for briquette.
According to the present invention, it is possible to provide a method of using tar slag as a binder suitable for briquette production.
According to the present invention, it is possible to provide a method for recovering tar slag, which is subject to a load on equipment operation for recovery from a tar decanter, with less load.

The schematic diagram which shows the tar decanter. The schematic diagram which shows the mechanism which collects a tar slag in a tar decanter. The schematic diagram which shows the molding machine and the evaluation apparatus of crushing strength used in an Example.

Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following description, and can be arbitrarily modified and carried out without departing from the gist of the present invention. In the following, "% by mass" and "% by weight", and "parts by mass" and "parts by weight" are synonymous with each other.
The terms used below shall be based on JIS M0104 (1984) unless otherwise specified.

[Recovery of tar components]
Coke is usually produced by carbonizing coal. The dry distillation conditions are not limited, but the temperature range is usually about 1000 to 1400 ° C., and in the case of coke for blast furnace, about 1100 to 1300 ° C., and coke is obtained by extruding from the coke oven and cooling after carbonization. In the coke oven, coke is produced by carbonization of coal, and tar components and coke oven gas are produced as dry distillation gas. Usually, about 70% by mass of the raw coal is coke, and about 30% by mass is discharged from the coke oven as a high-temperature (about 500 to 800 ° C.) dry distillation gas to become a tar component and coke oven gas.

The tar component and coke oven gas are discharged from the carbonization chamber of the coke oven to the riser pipe, and are cooled to 100 ° C or lower, usually about 80 to 85 ° C by water cooling (flushing), and the gas component (coke oven gas) and other components. Is separated into.
The tar component and the coke oven gas are sent to the gas refining facility and the tar refining facility (tar decanter), respectively, through the air collecting pipe arranged along the coke oven. Of these, the tar component is sent to a tar decanter together with cooling water, separated into cooling water, tar, and tar slag, and then appropriately distilled to be refined into various fractional products and pitches.

The components of tar are light oils such as benzene, toluene and xylene; carbol oils such as taric acids and naphthalene; medium oils such as naphthalene, methylnaphthalene, high boiling taric acid and tar bases; cleaning oils; anthracene oils such as anthracene; Contains creosote oil, etc.
The tar and tar slag in the present invention (hereinafter, these may be collectively referred to as "tar component") are solid-liquid components produced as a by-product when coal is dried and distilled to produce coke. It is not clearly distinguished from tar slag. Usually, a liquid substance containing substantially no solid content is referred to as tar, and a substance containing a solid substance (sludge) is referred to as tar slag. The solid content constituting the tar residue includes coal and coal that has been partially pyrolyzed.

[Tar decanter]
As described above, the water and tar components separated from the coke oven gas are statically separated into water, tar, and tar slag in the tar decanter and separated and recovered. A scraper is installed at the bottom of the tar decanter to scrape up the tar slag, and it is operated appropriately to separate and recover the tar slag that has settled at the bottom to the outside of the tar decanter system. Since the scraper passes through the tar portion when operating inside the tar decanter, the tar residue separated and recovered contains a part of tar content.

1 and 2 show a schematic view of the tar decanter. The tar decanter 1 is a storage tank having a substantially rectangular parallelepiped shape, and is provided with an inflow port 2 for a mixture of water, tar, and tar slag, a water drain port 3 (weir), a tar outlet 4, a scraper 6 for collecting tar slag, and the like. .. The solid-liquid mixture in the tar decanter can be separated into water a, tar b, and tar slag c in order from the top inside the tar decanter over time.
The separated water overflows from the water drainage port 3 (weir) installed on the upper part of the tar decanter and is sent to the tank by piping. Further, the separated tar b is extracted from the pipe of the tar outlet 4 installed on the side surface of the tar decanter and sent to the distillation facility by a pump.

The tar slag c that has settled on the bottom of the tar decanter is physically scraped up by the scraper 6 and stored in the tar slag receiver 8 installed outside the tar decanter. The operation of the scraper 6 is usually carried out by periodically operating the scraper 6 for a certain period of time to scrape up the tar slag that has settled on the bottom and transfer it to the tar slag receiver 8 installed outside the tar decanter. When the scraper 6 is operated, tar slag having a low tar content is initially recovered, but tar slag having a high tar content is recovered over time.

[Binder for briquette consisting of a mixture of tar and tar slag]
The binder for briquette of the present invention is a mixture of tar and tar slag, has a viscosity of 330 mPa · s or less at 70 ° C., and has a weight loss (A) of 87 when heated from room temperature to 900 ° C. Has a specific property of being less than or equal to%. The details are shown below.

The lower limit of the viscosity of the binder for briquette of the present invention at 70 ° C. is not limited, but is usually 56 mPa · s or more. If the viscosity at 70 ° C. is less than 56 mPa · s, it may adhere to the mold portion of the molding machine at the time of molding, the yield of the briquette may decrease, and the productivity may deteriorate. The viscosity at 70 ° C. is preferably 60 mPa · s or more, more preferably 70 mPa · s or more for the same reason as described above.
On the other hand, the binder for briquette of the present invention has an upper limit of viscosity at 70 ° C. of 330 mPa · s or less. If the viscosity at 70 ° C. exceeds 330 mPa · s, it becomes difficult to mix the briquette coking coal and the briquette binder, which is not preferable. The viscosity at 70 ° C. is preferably 300 mPa · s or less, more preferably 250 mPa · s or less, still more preferably 200 mPa · s or less for the same reason as described above.
Here, as the viscosity at 70 ° C., a value measured by a TVC-7 type viscometer manufactured by Toki Sangyo Co., Ltd. is used.

The lower limit of the weight loss amount (A) when the binder for briquette of the present invention is heated from room temperature to 900 ° C. is not limited, but is usually 65% or more. If the weight loss (A) when heated from room temperature to 900 ° C. is less than 65%, it may be difficult to mix the briquette coking coal and the briquette binder. The weight loss (A) when heated from room temperature to 900 ° C. is preferably 70% or more, more preferably 76% or more for the same reason as described above.
On the other hand, in the binder for briquette of the present invention, the upper limit of the weight loss amount (A) when heated from room temperature to 900 ° C. is 87% or less. If the weight loss amount (A) when heated from room temperature to 900 ° C. exceeds 87%, it adheres to the mold portion of the molding machine at the time of molding, the yield of the briquette decreases, and the productivity deteriorates, which is not preferable. The weight loss (A) when heated from room temperature to 900 ° C. is preferably 85% or less, more preferably 83% or less for the same reason as described above.
Here, the amount of weight loss (A) when heated from room temperature to 900 ° C. can be measured based on JIS M8812.

The lower limit of the weight loss amount (B) when the binder for briquette of the present invention is heated from room temperature to 400 ° C. is not limited, but is usually 44% or more. If the weight loss (B) when heated from room temperature to 400 ° C. is less than 44%, it may be difficult to mix the briquette coking coal and the briquette binder. The weight loss (B) when heated from room temperature to 400 ° C. is preferably 47% or more, more preferably 50% or more for the same reason as described above.
On the other hand, in the binder for briquette of the present invention, the upper limit of the weight loss amount (B) when heated from room temperature to 400 ° C. is not limited, but is preferably 55% or less, more preferably 54% or less. If the amount of weight loss (B) when heated from room temperature to 400 ° C. exceeds the above upper limit, it may adhere to the mold part of the molding machine at the time of molding, the yield of the briquette may decrease, and the productivity may deteriorate. is there.
Here, the weight loss amount (B) when heated from room temperature to 400 ° C. can be measured by setting the temperature of the furnace to 400 ° C. based on JIS M8812.

Tar slag is a substance in which tar is attached to granular carbonaceous material such as coke powder and coal powder. Therefore, when comparing tar and tar slag, it can be easily inferred that the amount of weight loss of tar slag when heated is smaller. However, comparing "the amount of weight loss when heated from room temperature to 900 ° C. (A)" and "the amount of weight loss when heated from room temperature to 400 ° C. (B)", under extremely high temperature heating conditions. In one former evaluation, the difference between tar and tar slag was considered to be small. However, according to the examination results of the present inventors, surprisingly, there are many differences between tar and tar slag in the evaluation of "weight loss when heated from room temperature to 900 ° C. (A)". , It has been found that it is possible to make it the most suitable binder for briquette by appropriately mixing it within a specific range.

Further, as shown below, by defining the difference in the amount of weight loss due to different heating temperatures as a relative ratio, it was possible to find a range that can be optimized as a binder for briquette.
The binder for briquette of the present invention is "a value obtained by dividing the weight loss amount (A) when heated from room temperature to 900 ° C. by the weight loss amount (B) when heated from room temperature to 400 ° C." (hereinafter, The lower limit of (may be indicated as “(A) / (B)”) is not limited, but is usually 1.40 or more. If (A) / (B) is less than 1.40, it may be difficult to mix the briquette coking coal and the briquette binder. Further, (A) / (B) is preferably 1.44 or more, more preferably 1.48 or more, for the same reason as described above.
On the other hand, in the binder for briquette of the present invention, the upper limit of (A) / (B) is not limited, but is usually 1.60 or less. If (A) / (B) exceeds 1.60, it may adhere to the mold portion of the molding machine at the time of molding, the yield of the briquette may decrease, and the productivity may deteriorate. Also, (A) / (
B) is preferably 1.55 or less, more preferably 1.50 or less, for the same reason as described above.

The method for obtaining the briquette binder of the present invention having the above characteristics by mixing tar and tar residue is not limited, but specifically, tar and tar residue are recovered and then mixed. It may be a method, or it may be recovered in a state where the tar and the tar slag are incompletely separated. Examples of the latter method include a method of recovering the tar slag from the tar layer before the tar slag is settled and separated, a method of recovering the tar slag with tar, and the like. That is, recovering a premixed product without having an independent mixing step is also included in the "mixing" in the present invention.

In particular, as a method for obtaining a binder for briquette of the present invention, among the above-mentioned methods, a method of recovering tar slag with tar is preferable. In this case, a specific method is to extend the operating time of the scraper and increase the tar content in the tar slag. Further, the same effect can be obtained by shortening the standing time in the tar decanter. By recovering the tar slag in this way, it becomes easy to prepare the binder for briquette of the present invention having the above-mentioned characteristics, and it is also possible to reduce the power load of the scraper.

In the binder for briquette of the present invention, tar slag may be crushed and then mixed with tar, or a mixture of tar and tar slag may be crushed. As described above, tar slag is a substance in which tar is attached to granular carbonaceous material such as coke powder and coal powder, so that it has high viscosity and poor fluidity, but it is crushed using a crusher. By performing the treatment, the above-mentioned viscosity characteristics and weight loss characteristics can be adjusted.

The binder for briquette of the present invention is not limited to the lower limit of the solid content having a particle size of 3 mm or less, but is usually 5% by weight or more. If the solid content of the particle size of 3 mm or less is less than 5% by weight, it may adhere to the mold portion of the molding machine at the time of molding, the yield of the briquette may decrease, and the productivity may deteriorate. The solid content having a particle size of 3 mm or less is preferably 8% by weight or more, more preferably 11% by weight or more, for the same reason as described above.
On the other hand, in the binder for briquette of the present invention, the upper limit of the solid content having a particle size of 3 mm or less is not limited, but it is usually 30% by weight or less. If the solid content having a particle size of 3 mm or less exceeds 30% by weight, it may be difficult to mix the briquette coking coal and the briquette binder. The solid content having a particle size of 3 mm or less is preferably 25% by weight or less, more preferably 20% by weight or less, for the same reason as described above.
Here, the amount of solid content having a particle size of 3 mm or less can be measured by washing the binder for briquette with a benzene reagent for about 10 minutes and then measuring the weight of the solid content passing through a sieve having an opening width of 3 mm.

[Briquette]
Hereinafter, the briquette for producing coke using the binder of the present invention (hereinafter, "briquette for producing coke" may be simply referred to as "briquette") and the method for producing the same will be described in detail. The briquette in the present invention contains at least a coking coal and a binder as raw materials thereof, and other components can be arbitrarily used.

[Molding coking coal]
The briquette targeted by the present invention contains at least pulverized coal as a coking coal (briquette coking coal). Further, it is preferable to use pulverized coal as a main component. Here, the "main component" means 50% by weight or more. The content ratio of pulverized coal in the molded coking coal is more preferably 70% by weight or more, further preferably 80% by weight or more, and particularly preferably 90% by weight or more.
In the present invention, "pulverized coal" means pulverized coal, and usually contains coal particles having a particle size of 3 mm or less in the range of about 70 to 90% by weight. That is, when the particle size of the coking coal used falls within the above range, it means that the coking coal is entirely composed of pulverized coal. In addition, pulverized coal is generally produced by crushing coal.

The pulverized coal used in the present invention is not limited as long as it corresponds to the above, but it is preferable to use a mixture of caking coal and non-slightly caking coal.
The caking coal refers to coal having the property of softening and melting when heated (caking property). Coke needs to have sufficient strength to withstand the pressure of the packed bed in the blast furnace during iron making and maintain a high porosity, and also needs to have high wear resistance that can suppress the generation of fine powder. It is preferable to use caking coal as a coke raw material in order to impart the characteristics.

Non-slightly caking coal refers to coal with a low degree of coalification that does not exhibit caking properties even when heated alone, or even if it does, the degree of caking is very small. This non-slightly caking coal is produced in a larger amount than caking coal worldwide and can be obtained at a lower cost than caking coal.
The reflectance of the non-slightly caking coal is not particularly limited, but is preferably 0.80% or less, more preferably 0.50 to 0.79%, and further preferably 0.60 to 0.78%. Is. The reflectance of non-slightly caking coal is the average maximum reflectance of vitrinit, and can be measured by, for example, the method defined by JIS M8816 (reflectance measuring method).

The maximum fluidity of the non-slightly caking coal is not particularly limited, but is preferably 0.9 to 4.0, and more preferably 1.0 to 2.7. The maximum fluidity of non-slightly caking coal is one of the indexes for evaluating the fluidity of coal, and the coking property of coal can be evaluated by this. The maximum fluidity can be measured by the method specified by JIS M8801 (Gee cellar plastometer method). The above-mentioned numerical range is a value obtained by converting the numerical value obtained by this measurement method into a common logarithm (unit: Log DDPM (Log Dial Division Per Minute)).

The volatile content of the non-slightly caking coal is not particularly limited, but is preferably 30 to 50% by weight, more preferably 32 to 40% by weight, and even more preferably 34 to 38% by weight. The volatile content is obtained by determining the weight percentage of the weight loss when the sample is heated at 900 ° C. for 7 minutes and then subtracting the quantified water content at the same time. For example, the method specified by JIS M8812 (volatile content). It can be measured by the quantification method).

The content (blending ratio) of the caking coal in the coking coal (briquette coking coal) is not limited, but is preferably 10 to 40% by weight, more preferably 15 to 35% by weight. The blending amount of the non-slightly caking coal in the coking coal (briquette coking coal) is not limited, but is preferably 60 to 90% by weight, more preferably 65 to 85% by weight. When the blending ratio of the caking coal in the pulverized coal is less than the above lower limit, the strength of the obtained coke tends to decrease. On the other hand, if the blending ratio of the caking coal in the coking coal (briquette coking coal) exceeds the above upper limit, the inside of the furnace may be clogged in coke production.

As mentioned above, non-slightly caking coal is produced in large quantities and can be obtained at low cost, so it is desirable to use as much as possible as a raw material for coke, but on the other hand, non-slightly caking coal has poor caking properties. , Increasing the content in the coke raw material tends to reduce the strength of coke.
A method for increasing the ratio of non-slightly caking coal used as coke coking coal can be achieved by using a high content ratio as a raw material for briquette. Further, as will be described later, it is also effective to optimize and add a binder as a raw material for briquette.

[binder]
The briquette of the present invention contains at least a binder for briquette of the present invention obtained by mixing tar and tar slag together with coking coal. As the binder, a binder other than the binder for briquette of the present invention can also be used in combination. Specific examples thereof include bottom pitch, petroleum pitch (asphalt pitch), bituminous substances such as petroleum asphalt, and solvent refined charcoal (solvent decalcification pitch).
Here, in the present invention, "pitch" and "petroleum pitch" mean a black resinous substance remaining by further vacuum-distilling the tar-like asphalt remaining when oil is distilled, or the asphalt thereof.
The bottom pitch means a heavy component (residual component) obtained by distilling a light component when coal tar is distilled, and is generally "soft pitch", "medium pitch", and "hard pitch". Is applicable. "Soft pitch", "medium pitch", and "hard pitch" are "70 ° C or lower", "70 to 85 ° C", and "70 to 85 ° C", respectively, when the coal tar atmospheric distillate is classified by the softening point (ring ball method). It means a fraction of "85 ° C. or higher".

The content of the binder in the briquette is not limited, but the lower limit thereof is usually 1% by weight or more, preferably 2% by weight or more, and more preferably 3% by weight or more. If the content of the binder in the briquette is less than the above lower limit, the binding of the coking coal becomes insufficient, the strength of the briquette tends to decrease, and it tends to be difficult to maintain the shape of the briquette. .. Furthermore, the strength of the obtained coke tends to decrease.
Further, the upper limit of the content of the binder in the briquette is not limited, but is usually 10% by weight or less, preferably 8% by weight or less, and more preferably 6% by weight or less. If the content of the binder in the briquette exceeds the upper limit, carbon may adhere to the coke oven and the furnace may be clogged.

The content ratio of the binder for briquette of the present invention among all the binders used for briquette is not limited, but the lower limit thereof is usually 1% by weight or more, preferably 2% by weight or more, and more preferably 3% by weight or more. Further, the upper limit of the content ratio of the binder for briquette of the present invention among all the binders is not limited, but is usually 10% by weight or less, preferably 8% by weight or less, and more preferably 6% by weight or less.

When petroleum pitch is used as the binder, the content in the briquette raw material is not particularly limited, but is preferably 1% by weight or more, and more preferably 2% by weight or more. When the content of petroleum pitch is less than the above lower limit, the strength of the briquette tends to decrease. On the other hand, the content of petroleum pitch is preferably 5% by weight or less, and more preferably 4% by weight or less. When the content of petroleum pitch exceeds the above upper limit, the productivity (yield) of coke tends to decrease.

[Manufacturing method of briquette]
The method for producing briquette in the present invention is carried out by mixing pulverized coal as coking coal and a binder and molding the mixture, and mainly has the following steps. Here, step 1 is optional.
[Step 1] Molded coking coal is mixed.
[Step 2] The blended coking coal and the binder are mixed.
[Step 3] The formulation of step 2 is molded.

[Step 1]
Step 1 is a step of blending and mixing coking coal to obtain pulverized coal, and the above-mentioned coking coal and non-slightly coking coal are appropriately blended and mixed as coking coal. Specifically, the coal may be mixed by naturally blending in the process of transferring the coal as a raw material, but it is preferable to use a kneader for homogenization. Further, the caking coal and the non-slightly crushed coking coal may be blended to obtain pulverized coal, or the coking coal may be blended and then crushed to obtain pulverized coal. Usually, a crusher is used to crush the coking coal.
The temperature at which the coking coal is mixed is not limited, but is usually 20 to 80 ° C. The time for mixing the coking coal is also not limited, but is usually 1 to 10 minutes.
The process and equipment for mixing and crushing the coking coal may be provided independently for the production of molded coal, but the process and equipment for blending and crushing coke coking coal other than the molded coking coal shall be adopted as they are. You can also. That is, a part of the coke coking coal may be separated as molded coking coal (pulverized coal) from the step of mixing and crushing the coke coking coal.

[Step 2]
Step 2 is a step of mixing pulverized coal as coking coal and a binder. The method of mixing the coking coal and the binder is not limited, but it is usually performed using a mixing device (mixer). Examples of the mixer include a rotary disk type mixer "Mix Muller Mixer" manufactured by Shinto Kogyo Co., Ltd., a Keihan company "KB Mixer Mixer", or a cylindrical horizontal type mixer manufactured by Chuo Kiko Co., Ltd. "Lady". Examples include "Gemixer" and "Apex Mixer" manufactured by Pacific Machinery & Engineering Co., Ltd.
When two or more kinds of binders are used, these may be mixed in advance, or one or a part thereof may be mixed with pulverized coal in step 1 and the other or the rest may be mixed in step 2. Good.

The temperature at which the pulverized coal and the binder are mixed is not particularly limited, but is preferably 20 ° C. or higher, more preferably 40 ° C. or higher, and further preferably 60 ° C. or higher. If the temperature at the time of mixing is less than the above lower limit, the strength of the briquette tends to decrease, and it tends to be difficult to maintain the shape of the briquette.
On the other hand, the upper limit of the temperature is not particularly limited, but is usually 200 ° C. or lower, preferably 150 ° C. or lower, and more preferably 100 ° C. or lower. If the temperature at the time of mixing exceeds the above upper limit, flammable gas is generated from the binder component and there is a risk of explosion inside the mixer, and it is necessary to inject an inert gas such as nitrogen into the inside of the mixer. May occur.
The temperature of the mixer can be adjusted by the temperature of the heat medium used.

[Step 3]
Step 3 is a step of molding the compound obtained in step 2 to obtain briquette. The method of molding the briquette is not limited, but usually, the briquette is molded using a mold or a wooden frame having a concave shape, a pressure molding machine, or the like. When the pressure molding machine is used, not only can a large amount of molded coal be continuously mass-produced, but also a large amount of molded coal can be consolidated at one time evenly, and the adhesiveness of the pulverized coal particles can be improved.
The method and mechanism of the pressure molding machine are not limited, but a pair of roller molds having recesses formed in the shape of briquette are used, and the briquette raw material is filled in the recesses when the rollers rotate. It is preferable that the mechanism is compressed.
The pressure conditions by such a pressure molding machine are not particularly limited, but the pressure (linear pressure) is preferably 0.8 to 2.0 t / cm, more preferably 1.0 to 1.2 t / cm. If the pressurization is less than the above range, briquette having sufficient strength may not be obtained.

The amount of water contained in the raw material at the time of molding is not limited, but is preferably 0.1% by weight or more, more preferably 1% by weight or more, and further preferably 2% by weight or more. On the other hand, the upper limit of the water content is not particularly limited, but is preferably 15% by weight or less, more preferably 13% by weight or less, and further preferably 12% by weight or less. If it is out of this range, the strength as briquette tends to be difficult to develop.

[Briquette]
The briquette targeted by the present invention is not limited in its use as long as it is used as a briquette for coke production, but it can be suitably used for iron making, and particularly preferably for a blast furnace.
The shape and various characteristics of the briquette obtained by the production method of the present invention are not limited, but are specifically exemplified as follows.

Specific examples of the shape of the briquette include a massec type, an egg type, a bale type, an almond type, a pillow type, a cube, a sphere, a rectangular parallelepiped, a cylinder, and a cone. Further, a portion that discharges the above-mentioned shape as the main body may be provided. Preferably, from the viewpoint of ease of molding, a massec type, a cube, a rectangular parallelepiped, or the like is preferable, and from the viewpoint of productivity, strength, and suppression of rolling of coke coking coal in a coal tower on a pile, a cone or a circle. Columnar columns such as columnar columns are preferable.
The thickness of the briquette is usually 10 to 50 mm, preferably 24 to 35 mm. If the thickness of the briquette is too large, the peelability from the molding machine tends to decrease during the molding process. On the other hand, if the thickness of the briquette is too small, the productivity tends to decrease, and the effect of improving the coke quality by using the briquette tends to decrease. The thickness of the briquette means the shortest diameter of the briquette body (excluding protrusions and the like).

The aspect ratio of the briquette is not limited, but is preferably 1.0 to 3.5, more preferably 1.5 to 3.0, and even more preferably 2.0 to 2.7. If the aspect ratio is too large, the molding process may be difficult or the briquette may be easily broken. Further, if the aspect ratio is too small, non-uniformity may occur when the mixture of coke coking coal and briquette is charged into the coal tower of the coke oven or the charging vehicle. In the present invention, the aspect ratio means the ratio (maximum length / shortest diameter) between the maximum length (maximum diameter) and the shortest diameter of the briquette.

The maximum length of the briquette is not particularly limited, but is preferably 100 mm or less, and more preferably 80 mm or less. When the maximum length of the briquette exceeds 100 mm, the strength of the briquette tends to decrease. On the other hand, the lower limit of the maximum length of the briquette corresponds to the lower limit of the thickness of the briquette described above, and the preferable lower limit is also the same.

Although the density of the molded coal is not limited, usually 0.90~1.40g / cm ^3, preferably 1.00~1.35g / cm ^3, more preferably 1.05~1.30g / cm ^3, more preferably Is 1.10 to 1.28 g / cm ³ . If the density of the briquette is less than the lower limit, the strength of the briquette becomes insufficient, and cracks tend to occur or the strength of the obtained coke tends to decrease. On the other hand, if the density of the briquette exceeds the upper limit, the charge weight becomes excessive, and each work machine may be overloaded.

[Coke manufacturing method]
The briquette obtained by the production method of the present invention is usually mixed with coke coking coal and charged into a coke oven.
By using briquette together with pulverized coal as a coke raw material, the strength of coke is improved. The main reasons are as follows. (1) By using a part of the coke coking coal as briquette, the distance between the coal particles is narrowed and the cohesiveness is improved. (2) By increasing the expandability of the briquette portion during coke production, consolidation of the surrounding pulverized coal portion is promoted, and the cohesiveness of the pulverized coal portion is also improved. (3) The softening and meltability of pulverized coal is improved by the binder contained in the briquette.

A specific example of a method for producing coke using briquette will be described below.
First, the coal as a raw material is transferred from the raw material yard (coal storage yard) to the compounding tank using a belt conveyor or the like. As described above, the coal used as a raw material for coke is caking coal or non-slightly caking coal. The temperature and blending time at the time of blending are the same as those in step 1 at the time of producing the briquette described above. Powdered coal as coke coking coal can be obtained by blending the raw material coal in the blending tank at the desired blending ratio and then crushing the raw material coal with a crusher. Alternatively, coal may be crushed in advance and blended.
As described above, a part of the coke coking coal mixed and crushed here can be separated and used as the molded coking coal.

The pulverized coal obtained by the above method and the briquette produced by the method of the present invention are mixed in a predetermined ratio, and then charged into a coking tower as coking coal for coke, and then charged into a coke oven. To
The mixing ratio of pulverized coal and briquette is not limited, but it is desirable to mix the briquette in an amount of usually 10% by weight or more, preferably 15% by weight or more, while usually 50% by weight or less, preferably 40% by weight or less. More preferably, it is blended in an amount of 30% by weight or less. If the blending ratio of the briquette is less than the above lower limit, the abundance ratio of the briquette in the coal tower may be biased (segregation) when the briquette is introduced into the coal tower. On the other hand, if the blending ratio of the briquette exceeds the upper limit, the strength of the obtained coke may decrease.

As mentioned above, the briquette is once stored in a storage tank such as a coal tower between the time it is molded and the time it is transported to the coke oven. Receives only the load. In addition, the briquette is usually transported to the coke oven by a belt conveyor, but there is also an impact when the belt of the belt conveyor is transferred. Due to such impact and load, if the strength of the briquette is low, the degree of pulverization increases, and as a result, the effect of improving the coke strength decreases.
On the other hand, the briquette obtained by the production method of the present invention can have a strength equal to or higher than that of the briquette produced by the conventional method, and further, the shape of the briquette can be optimized. By optimizing the method of producing briquette, it is possible to produce coke with higher strength. Therefore, the above-mentioned problems can be solved.

Coke can be obtained by carbonizing the coking coal (combination of pulverized coal and briquette) charged into the coke oven in the coke oven. Known conditions are appropriately adopted as the conditions for carbonization, and carbonization is usually carried out at 1,100 to 1300 ° C. for 18 to 20 hours.

Examples of the present invention are shown below. The following examples are examples for confirming the effect of the present invention, and the present invention is not limited to this example. The present invention does not deviate from the gist of the present invention, and various conditions can be adopted as long as the object of the present invention is achieved.

[Raw material for briquette]
<Molding coking coal>
The following molded coking coals were pulverized to obtain pulverized coal (containing 70 to 90% by weight of coal having a particle size of 3 mm or less). The caking coal was blended at a ratio of 30% by weight and the non-slightly caking coal at a ratio of 70% by weight to prepare a blended coal in which the water content was adjusted to 9.5% by weight.
-Caking coal: Reflectance 1.46%, maximum fluidity 2.03 Log DDPM, volatile content 18.6%
-Non-slightly caking coal: reflectance 0.70%, maximum fluidity 2.64 Log DDPM, volatile content 36.4%
<Binder>
-Asphalt pitch: Petroleum-derived asphalt solvent pitch (ASP) was used (softening point: 252 ° C.).

[Characteristics of briquette binder]
<Viscosity at 70 ° C>
It was measured at 70 ° C. using a TVC-7 type viscometer manufactured by Toki Sangyo Co., Ltd.
<Amount of decrease in heating up to 900 ° C (A)>
Measured based on JIS M8812.
<Reduction in heating up to 400 ° C (B)>
Based on JIS M8812, the temperature of the furnace was set to 400 ° C. for measurement.
<Amount of solids with a particle size of 3 mm or less>
After washing the binder for briquette with a benzene reagent for about 10 minutes, the weight of the solid content passing through a sieve having an opening width of 3 mm was measured.

<Crushing strength test of briquette>
About 20 g of the briquette raw material (raw material mixture) obtained by kneading the briquette coking coal, the binder for briquette and the asphalt pitch is charged into the molding machine shown in FIG. 3 (a), and the pressure is applied at 40 MPa for 30 seconds. Obtained a cylindrical briquette having a diameter of 30 mm and a height of 30 mm.
The obtained briquette was installed in a crushing tester (SV-55C-20M type manufactured by Imada Seisakusho) shown in FIG. 3B, compressed at a compression speed of 30 mm / min, and the strength at break was measured. did. As shown in FIG. 3B, the briquette was installed so that the circular cross section was in the vertical direction.

[Example 1]
The cooling water and tar components separated from the gas refining equipment of the coke oven were supplied to the tar decanter shown in FIG. 1 and allowed to stand sufficiently at room temperature to separate them into water, tar and tar slag. After separation, tar was collected from the tar layer and tar slag was collected from the bottom.
The obtained tar and tar slag were sufficiently mixed so that the mixing ratio was 90:10 to prepare a binder for briquette.
As a result of analyzing the properties of the obtained binder for briquette, the viscosity at 70 ° C. was 80 mPa · s, the amount of heat reduction (A) up to 900 ° C. was 81.0% by weight, and the amount of heat reduction up to 400 ° C. (B). ) Was 54.8% by weight.
To 97 parts by weight of the molded coking coal, 5 parts by weight of the binder obtained above and 3 parts by weight of asphalt pitch were added and kneaded manually for about 2 minutes.
Briquette was produced by the method described above using the kneaded raw material mixture, and the crushing strength was measured and found to be 71.0 N.

[Examples 2 and 3, Comparative Example 2]
The binders for briquette were adjusted in the same manner as in Example 1 except that the mixing ratios of tar and tar slag were as shown in Table-1. Table 1 shows the results of measuring the properties of the obtained binder for briquette in the same manner as in Example 1.
Table 1 shows the results of producing briquette using the obtained binder for briquette in the same manner as in Example 1 and measuring the crushing strength.

[Comparative Example 1]
The tar was used as it was as a binder for briquette without using a binder for briquette containing tar and tar slag. Table 1 shows the results of measuring the properties of tar in the same manner as in Example 1.
Table 1 shows the results of producing briquette using tar as a binder for briquette and measuring the crushing strength in the same manner as in Example 1.

[Comparative Example 3]
The tar slag was used as it was as a binder for briquette without using a binder for briquette in which tar and tar slag were mixed. Table 1 shows the results of measuring the properties of the tar slag in the same manner as in Example 1.
Table 1 shows the results of measuring the crushing strength of briquette produced by using tar slag as a binder for briquette in the same manner as in Example 1.

As shown in Table 1, by adjusting the mixing ratio of tar and tar slag, the viscosity at 70 ° C., the weight loss amount up to 400 ° C., and the weight loss amount up to 900 ° C. can be set in a specific range. It was. The briquette using the briquette binders of Examples 1 to 3 having these characteristics within a predetermined range has significantly higher crushing strength than the briquette coal using the briquette binders of Comparative Examples 1 to 3. It was confirmed that it was high.

[Example 4]
The cooling water and tar components separated from the gas refining equipment of the coke oven were supplied to the tar decanter shown in FIG. 1 and allowed to stand for 4 hours. After that, the scraper of the tar decanter shown in FIG. 2 was activated and continuously operated. After a lapse of a predetermined time after starting the scraper, the tar slag (mixed with tar) was sampled, and the viscosity at 70 ° C. was measured in the same manner as in Example 1.
Table 1 shows the results of comparing the obtained viscosity values at 70 ° C. with the viscosities at 70 ° C. measured in Examples 1 to 3 and Comparative Example 2 and confirming a sample with a scraper start-up time corresponding thereto. Shown in. The briquette binders prepared in Examples 1 to 3 and Comparative Example 2 were obtained by mixing tar recovered from a tar decanter and tar slag, and from the results in Table 1, the same properties were obtained. It was found that the briquette binder having can be achieved by adjusting the scraper start-up time of the tar decanter and recovering it as tar slag.

1 Tar decanter 2 Solid-liquid mixed distribution inlet 3 Moisture outlet 4 Tar outlet 5 Tar slag discharge port 6 Scraper 7 Scraper drive unit 8 Tar slag receiver 9 Evaluation molding machine 10 Crush strength tester a Moisture b Tar c Tar slag d Briquette raw material e Briquette

Claims (4)

By controlling the elapsed time after the start of scraper from the solid-liquid component produced by carbonization of coal to produce coke,
The elapsed time after starting the scraper is 100 minutes or more,
By recovering tar and tar slag and mixing them, the viscosity at 70 ° C is 56 mP.
A · s or more and 330 mPa · s or less, and the amount of weight loss when heated from room temperature to 900 ° C.
A method for producing a binder for briquette, wherein A) is obtained as having 65% or more and 87% or less. The method for producing a binder for briquette according to claim 1, wherein the amount of weight loss (B) when heated from room temperature to 400 ° C. is 44 to 55%. The value ((A) / (B)) obtained by dividing the amount of weight loss (A) when heated from room temperature to 900 ° C. by the amount of weight loss (B) when heated from room temperature to 400 ° C. is 1.40 to The method for producing a binder for molded charcoal according to claim 1 or 2, which is obtained as 1.60. The method for producing a binder for briquette according to any one of claims 1 to 3, wherein tar and tar slag are separated by a tar decanter.

Images