JP4714518B2 - Manufacturing method of coal - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a method for producing a coal for charging into a coke oven when producing metallurgical coke.

  Coking coal is dried and heated in advance and charged into the coke oven, shortening the carbonization time and increasing the charging density, which makes it possible to improve coke quality. .

  As such a method, for example, as in the technique described in Patent Document 1, the coke oven charging coal is heated to 250 ° C. or more and 350 ° C. or less and classified, and pulverized coal having a particle size of 0.3 mm or less is 350 There is a method of heating to 450 ° C. or higher and press molding, softening and melting pulverized coal, and molding.

JP 09-13042 A

  In the technique described in Patent Document 1, the strength of the coal is weak because it is molded by melting the caking coal at 350 ° C. to 450 ° C. and no binder is added. For this reason, before charging into the coke oven, the coal coal collapses and pulverized coal is regenerated. When the pulverized coal is charged, the pulverized coal rises in the carbonization chamber in accordance with the flow of the pyrolysis gas rapidly generated from the coal, and is then introduced into the gas purification process.

  The pulverized coal charged in the coke oven is carbonized on the surface of the high-temperature carbonization chamber wall, forming a thick carbon layer, making the coke oven extrusion difficult. Further, tar is separated from the pyrolysis gas introduced into the gas purification process, but the pulverized coal is mixed into the tar to lower the tar purity, which has a problem of adversely affecting the coke production process.

  The present invention has been proposed to solve such a problem, and an object of the present invention is to produce a high-strength coal by preventing the mixture of pulverized coal into tar.

  The method for producing a coal char of the present invention has been made in order to solve the above-mentioned problems. As a first means, a binder is added to a heated pulverized coal and kneaded, followed by pressure molding to form the coal char. In the manufacturing method, the particle size distribution after kneading of pulverized coal and a binder is 600 μm or more: 35 mass% to 50 mass%, and 75 μm or less: 5 mass% to 15 mass%.

  Further, as a second means, the temperature of the pulverized coal before adding the binder is set to 135 ° C. to 170 ° C.

  Further, as a third means, in order to create the above-described particle size distribution, the kneading time of the heated pulverized coal and the binder is set to 1 to 2 minutes.

According to the method for producing coking coal of the present invention, it becomes possible to improve the strength of the coking coal and to suppress the collapse and pulverization of the forming coal in the conveying process to the coke oven. Generation of a carbon layer on the interior wall surface can be suppressed and coke extrusion load can be reduced.
In addition, the effect in this field is great, such as the reduction of tar purity in the gas purification process.

This inventor investigated and examined about the method of manufacturing the coking coal which has sufficient intensity | strength which does not affect a coke manufacturing process, using the coking coal manufactured with the coal forming apparatus shown in FIG.
This coal forming equipment is extracted from a heater 1 that heats differential coal of 0.7 mm or less to 150 ° C. in a nitrogen atmosphere and tar produced as a by-product from the coke production process that has fluidity in this heated pulverized coal. A paddle mixer 2 having 16 paddle blades to which a binder is added and kneaded, and a double roll type molding machine 3 for producing coking charcoal by pressurizing the kneaded material with a roll provided in parallel (linear pressure 45 kPa) Have.

  In addition, as the binder, tar gas oil, carbol oil, naphthalene oil, washing oil and the like, low boiling oil is 10 mass%, the total of light oil such as creosote oil and pyrene and the low boiling oil is 20 mass%, A pitch containing 65 mass% and sludge containing 5 mass% were used.

  Using this coal forming equipment, the kneading time in the paddle mixer 2 was changed to obtain kneaded materials having different particle size distributions, and this kneaded material was press-molded with a double roll type molding machine to produce the coal. The charcoal was charged into a strength measuring machine and its strength was measured. The intensity measurement results are shown in FIGS. 2 (a) and 2 (b).

  In addition, the intensity | strength measurement used the measuring machine which installed the cylindrical rotary body of diameter 125mm and length 700mm horizontally. And while charging charcoal in this rotary body and introducing nitrogen heated at 150 degreeC and rotating for 3 minutes at 20 rpm, it took out and measured the ratio of 1 mm or more.

  As is clear from FIG. 2 (a), the strength of the formed coal sharply decreases when the kneaded material having a particle size of 600 μm or more is less than 35 mass%, and the strength rapidly increases when the kneaded material of 600 μm or more exceeds 50 mass%. To drop. From this, in the manufacturing method of the forming charcoal of this invention, the kneaded material with a particle size of 600 micrometers or more was 35 mass%-50 mass%.

  Further, as apparent from FIG. 2 (b), when the kneaded product having a particle size of 75 μm or less is less than 5%, the strength of the coal is rapidly decreased, and when it exceeds 15%, the strength is rapidly decreased. For this reason, in the method for producing coal coal of the present invention, the kneaded product having a particle size of 75 μm or less was made 5% to 15%.

For example, when coal is produced by pressure molding with a double roll molding machine, the bulk density of pulverized coal before pressure molding is about 0.6 t / m ³ , and the bulk density of coal after pressure molding is about 0.6 t / m ^3. Is about 1.0 t / m ³ , and a certain amount of deaeration is possible.

  However, when the pulverized coal contains a large amount of gas and the bulk density is low, the gas remains in the coal as it is not sufficiently degassed even by pressure molding. As a result, since the gas expands when the pressure in the double roll molding machine is removed, the surface of the coal is cracked and the strength of the coal becomes weak.

  From this, if the ratio of the kneaded product having a particle size of 600 μm or more and 75 μm or less is within the range of the present invention, the bulk density of the kneaded product becomes high and the pressure is molded in the molding machine. It is presumed that the pressure of the remaining gas is low and the expansion of the coal does not occur and cracks do not occur.

  That is, when the kneaded material having a particle size of 600 μm or more exceeds 50 mass%, there are few fine powders entering into the large voids formed by pseudo particles of 600 mm or larger, the large voids are not filled, and the bulk density rapidly decreases, while 35 mass% If it is less than this, the number of pseudo particles less than this particle size increases, and a large amount of small voids are generated to reduce the bulk density. As a result, cracks occur in the coal and it is estimated that the strength is weak.

  Moreover, when the kneaded material with a particle size of 75 micrometers or less becomes less than 5 mass%, there will be few fine powders which enter into the space | gap formed between the pseudo particles more than this, and a bulk density will fall similarly to the above. Moreover, when the kneaded material of 75 micrometers or less exceeds 15 mass%, it is estimated that it will be excessively fine and a bulk density will fall similarly to the above, and a crack will generate | occur | produce in a formed charcoal and intensity | strength will become weak.

  Moreover, in order to improve the productivity of coke, it is preferable to heat and shape | mold pulverized coal to high temperature. A binder is added to the pulverized coal. The higher the temperature of the binder, the more expensive the binder is required.

  For this reason, as a result of investigating binders that are inexpensive and moldable at as high a temperature as possible, the inventor as a by-product of coke production process as proposed in Japanese Patent Application Laid-Open No. 2004-149647. It has been found that binders extracted from are preferred.

  The composition of this binder is 10 mass% or less for low boiling oils such as tar light oil, carbol oil, naphthalene oil, and washing oil, and the total of light oils such as creosote oil and pyrene and the low boiling oil is 15 to 25 mass%. The pitch is preferably in the range of 65 to 80 mass% and the sludge in the range of 5 to 10 mass%.

When this binder is used, when the temperature of the pulverized coal exceeds 170 ° C., the viscosity of the binder becomes less than or equal to water (less than about 1 × 10 ⁻³ Pa · s). For this reason, the caking force is also reduced, and if the mixture is excessively kneaded, the generated pseudo particles are disintegrated and the particle size of the kneaded product is unlikely to fall within the particle size distribution range of the present invention. Moreover, if it is less than 135 degreeC, the productivity of coke cannot fully be improved and it is unpreferable.
From this, the temperature of pulverized coal is 135-170 degreeC in the manufacturing method of the forming coal of this invention.

Furthermore, the present inventor investigated the kneading time by the paddle mixer in order to bring the particle size distribution of the kneaded material into the above range.
As a result, the viscosity of the binder having a pulverized coal temperature of 135 ° C. to 170 ° C. is about water (about 1 × 10 ⁻³ Pa · s). Therefore, the kneading time was changed variously, and the particle size of the pseudo particles as the kneaded product at that time was measured. The results are shown in FIGS. 3 (a) and 3 (b).
In addition, the measuring apparatus which measures a quasi-particle used the multistage type vibration sieve with a sieve mesh of 600 micrometers, 300 micrometers, and 75 micrometers.

  As shown in FIGS. 3A and 3B, when the kneading time is less than 1 minute, sufficient pseudo particles are not generated, and the kneaded material of 600 μm or more does not become 35 mass% or more. At the same time, since a large amount of powder remains, the kneaded material of 75 μm or less does not become 15 mass% or less. Further, when the kneading time exceeds 2 minutes, the pseudo particles disintegrate, so that the kneaded material of 600 μn or more does not become 50 mass% or less, and the kneaded material of 75 μm or less does not become 15 mass% or less.

  As a result, pulverized coal having a temperature before kneading of 135 ° C. to 170 ° C. is kneaded so that a kneaded product of 600 μm or more has a particle size distribution of 35 mass% to 50 mass% and a kneaded product of 75 μm or less has a mass distribution of 5 mass% to 15 mass%. In order to obtain, it is preferable to set the binder kneading time to 1 to 2 minutes.

  In the present embodiment, the kneading is performed using a paddle mixer. However, the present invention is not limited thereto, and the kneading may be performed using a kneader such as a pin mixer or a mix muller.

Examples of the present invention and comparative examples will be described with reference to Table 1.
In both the examples and comparative examples of the present invention, low-boiling oils such as tar light oil, carbol oil, naphthalene oil, and washing oil heated to 150 ° C. in pulverized coal having a particle size of 0.7 mm or less are 10 mass%, cleo 16 paddle blades were added while adding 7mass% of pulverized coal to a binder containing 20mass% of light oil such as sort oil, pyrene and the low boiling oil, 65mass% of pitch and 5mass% of sludge. It knead | mixed with the paddle mixer which has. And after that, this kneaded material is what produced the charcoal by pressurization of 45 kPa with a double roll type molding machine.

  In Examples 1 to 3, as shown in Table 1, since the pulverized coal temperature, the kneading time, and the particle size of the kneaded material are within the above-described range of the present invention, it was possible to obtain good strength of the forming coal. .

  Moreover, since the temperature of the pulverized coal before adding a binder deviated from the upper limit of the preferable range of the present invention in Example 4, the strength of the formed coal was slightly reduced as compared with Examples 1 to 3.

  In contrast, since Comparative Example 1 has a long kneading time in a paddle mixer and Comparative Example 2 has a short kneading time, a kneaded product having a particle size of 600 μm or more is outside the lower limit of the present invention, and a kneaded product of 75 μm or less. Also, since the upper limit of the present invention was exceeded, the strength of the coal was low.

It is a coal heating process flowchart in the manufacturing method of the forming coal of this invention. Explanatory drawing (a) which shows the relationship between the kneaded material of 600 micrometers (%) or more obtained by using the manufacturing method of the present invention and the strength of coal, and the kneaded material of 75 micrometers or less (%) and the coal It is explanatory drawing (b) which shows the relationship with an intensity | strength. It is explanatory drawing which shows the relationship between the kneading | mixing time and the particle size distribution of a kneaded material in the manufacturing method of the forming coal of this invention.

Explanation of symbols

1 Heating machine 2 Paddle mixer 3 Double roll type molding machine

Claims (3)

  In the method of producing a coal molding by adding a binder to heated pulverized coal and then kneading, the particle size distribution after the pulverized coal and binder are kneaded is 600 μm or more: 35 mass% to 50 mass%, and 75 μm or less. : 5mass%-15mass%, The manufacturing method of the forming charcoal characterized by the above-mentioned.   The method for producing a coal charcoal according to claim 1, wherein the temperature of the pulverized coal before adding the binder is 135 ° C to 170 ° C. The method for producing a coal charcoal according to claim 2, wherein the kneading time of the heated pulverized coal and the binder is 1 to 2 minutes.

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