KR20090060339A - Method of manufacturing ashless coal - Google Patents

Abstract

This invention is a manufacturing method of the ashless coal used as raw coal of steel coke, The slurry obtained by mixing a solvent and coal to prepare a slurry (S1), and the slurry obtained by the slurry preparation process (S1) 400-420 After extracting at a temperature of 20 ° C. or less for 20 minutes, an extraction step (S2) of cooling at 370 ° C. or less, a separation step (S3) of separating the slurry obtained in the extraction step (S2) into a liquid part and a non-liquid part, and a separation step ( And a reformed coal acquisition step (S4) of separating the solvent from the liquid portion separated in S3) to obtain ashless coal, which is reformed coal.

Description

Production Method of Ashless Coal {METHOD FOR PRODUCTION OF ASHLESS COAL}

TECHNICAL FIELD This invention relates to the manufacturing method of the ashless coal which produces the ashless coal used for the raw coal of steelmaking coke from coal.

Conventionally, as a raw coal of steel coke, such as a blast furnace coke, the thing which mix | blended weak coking coal and non-coking coal centered around high quality coking coal was used, In recent years, attempts have been made to extract components that are soluble in solvent from coal and obtain extract coal of higher quality than the raw coal.

For example, bituminous coal, sub-bituminous coal, lignite, agaltan and the like are used as raw materials coal, and mixed with liquefied oil as a solvent to form a slurry. Discloses a method of hydrogenating and liquefying using a catalyst under high temperature and high pressure, separating and finally extracting the produced SRC (solvent refined coal), and using this for coke raw coal (see Patent Document 1, for example). ).

In addition, since coking coal is depleted in resources and expensive, in particular, non-coking coal, low-grade brown coal and sub-bituminous coal, such as nitro coal, are taken into account and coking coal is used as a raw coal. The development and proposal which manufacture the extract coal which has the same characteristic as this and use as a raw coal for coke is also performed.

For example, low-grade coal such as lignite or sub-bituminous coal is heat-treated in a solvent (medium liquid) having a pressure of 1 to 20 MPa and a temperature of 400 ° C. or lower, and then the solvent and the heat-treated coal are fractionated to obtain a heat-treated coal, which is obtained from coking raw coal. The method used as a part is disclosed (for example, refer patent document 2).

Moreover, as a manufacturing method of ashless coal which removed ash in coal efficiently, a raw material coal is N-methyl- 2-pyrrolidinone (NMP) solvent only, or mixed solvent of carbon disulfide and N-methyl- 2-pyrrolidinone. The method of extracting ashless coal from raw material coal by making it contact in presence of a chlorine or a fluorine compound is disclosed (for example, refer patent document 3).

Patent Document 1: Japanese Patent Application Laid-open No. Hei 8-269459 (paragraphs 0010 to 0032)

Patent Document 2: Japanese Patent Application Laid-Open No. 2003-55668 (paragraphs 0017 to 0030)

Patent Document 3: Japanese Patent Application Laid-Open No. 2001-26791 (paragraphs 0009 to 0022)

However, there was a problem shown below in the method for producing the above-mentioned extract coal.

In the manufacturing method of patent document 1, ash and a used catalyst are concentrated in the obtained SRC, and it cannot be said that quality is enough to use it as raw coal of steel coke. In addition, although the soft meltability (softening fluidity), which is an important quality as a binder (coking filler) for the coke raw material, is provided, the solidification characteristics at 400 to 500 ° C are insufficient due to excessive volatility, so that SRC is used as a binder. It was also difficult to produce coke with high enough strength. In addition, this SRC requires expensive hydrogen and a catalyst in terms of its production method, and must be carried out under conditions of high temperature and high pressure, resulting in an increase in manufacturing and equipment costs, and thus there is a problem of not being economical.

Although the manufacturing method described in patent document 2 is low in cost compared with the method by the said liquefaction, since the obtained heat-treated coal is a mixture of the extract and the non-extract by a solvent, the quality which is an important point as a raw material for coke, such as softening meltability, is It was not enough.

The manufacturing method described in Patent Document 3 is to extract a solvent soluble component with coal using a strong polar solvent such as NMP without adding hydrogen, but when the polar solvent is used as the solvent, the solvent forms a strong bond with coal. Therefore, the recovery of the solvent is not easy, and as a result, there is a problem that the production cost of ashless coal is increased.

This invention is made | formed in view of the said subject, The objective is to provide the manufacturing method of ashless coal which has the outstanding quality as a raw coal used for coking for steelmaking while making ashless coal high efficiency and inexpensive. .

The present inventors have intensively studied the method for producing ashless coal used in the raw coal of steel coke, and as a result, the ashless coal is efficiently produced and the softening meltability (softening fluidity) when the blended coal is used is inhibited. By discovering the relationship between temperature and time in the extraction process that results in unqualified quality, the inventors have invented a method for producing ashless coal which can produce high efficiency and low cost ashless coal that can be used for raw coal of steel coke. .

That is, the manufacturing method of the ashless coal which concerns on this invention is a manufacturing method of the ashless coal used for the raw coal of steel coke, The slurry preparation process which mixes a solvent and coal, and prepares a slurry, The slurry obtained by the said slurry preparation process 20 minutes or less at a temperature of 400 to 420 ° C., followed by an extraction step of cooling to 370 ° C. or less, a separation step of separating the slurry obtained in the extraction step into a liquid part and a non-liquid part, and a liquid separated in the separation step. And a reformed coal acquisition step of separating the solvent from the unit to obtain ashless coal, which is reformed coal.

According to such a manufacturing method, in a slurry preparation process, a solvent and coal which is a raw material of ashless coal are mixed, and a slurry is prepared. In addition, in the extraction step, by treating the slurry obtained in the slurry preparation step under conditions of a predetermined temperature and time, the proportion of the coal component extracted into the solvent is increased, and the coal component is extracted in the solvent with high efficiency and the ashless obtained The restocking temperature of the coal increases. Further, in the separation step, the slurry obtained in the extraction step is separated into a liquid part, which is a solution containing a coal component extracted in a solvent, and a non-liquid part, which is a slurry containing an insoluble coal component in a solvent. In the reformed coal acquisition step, the solvent is separated from the liquid portion separated in the separation step to produce ashless coal.

In the method for producing anthracite coal according to the present invention, in addition to obtaining anthracite coal in the reformed coal acquisition step, the solvent is separated from the non-liquid portion separated in the separation step to produce reformed coal. I) to obtain.

According to this production method, in addition to the production of ashless coal in the reformed coal acquisition step, the solvent is separated from the non-liquid portion separated in the separation step to produce by-product coal.

The method for producing anthracite coal according to the present invention is characterized in that, in the extraction step, the slurry obtained in the slurry preparation step is heated to a temperature of 400 to 420 ° C. and extracted, and then immediately cooled to 370 ° C. or less.

According to this manufacturing method, in the extraction step, the slurry obtained in the slurry preparation step is heated to a predetermined temperature and extracted, and then immediately cooled to 370 ° C. or lower without performing temperature maintenance, whereby the proportion of the coal component extracted into the solvent is increased. It is higher and this coal component is extracted more efficiently in a solvent.

The method for producing ashless coal according to the present invention is characterized in that the coal is nitric coal. According to such a production method, by using inexpensive nitric coal as coal which is a raw material of ashless coal, ashless coal can be produced at a lower cost.

According to the method for producing ashless coal according to the present invention, the ashless coal used in the raw coal of steel coke can be produced at high efficiency or inexpensively. In addition, when the ashless coal is blended with the raw coal, the softening meltability of the blended coal can be increased, and the amount of expensive coking coal can be suppressed, thereby reducing the cost of the raw coal for steel coke. The improvement of the intensity | strength of steel coke can also be aimed at by the adhesive improvement of a coal blend. In addition to ashless coal, by-product coal can also be produced with high efficiency and low cost.

1 is a flowchart for explaining a step of a method for producing ashless coal.

It is a schematic diagram which shows the solid-liquid separation apparatus for performing a gravity sedimentation method.

It is a graph which shows a Gisella curve by the softening flow test in Example 1. FIG.

FIG. 4 is a graph showing the relationship between the extraction temperature when the sub-bituminous coal C in Example 2 is used as the raw coal and the extraction process is performed at an extraction time of one hour and the ash-free c obtained.

Fig. 5 shows sub-bituminous coal C in Example 3 as the extraction temperature, which is heated to 370 ° C., 400 ° C. and 420 ° C. in the preheater and held in the extractor for a predetermined time, and then quenched to 360 ° C. for extraction. A graph showing the relationship between extraction time and extraction rate.

[Description of the code]

S1: slurry preparation process

S2: Extraction Process

S3: Separation Process

S4: modified coal acquisition process

1: Coal Slurry Preparation

2: pump

3: preheater

4: extraction tank

5: gravity sedimentation tank

6: solid concentrate container

7: cooler

8: filter unit

9: supernatant container

10: stirrer

100: solid-liquid separator

Next, the manufacturing method of the ashless coal which concerns on this invention is demonstrated in detail with reference to drawings. 1 is a flowchart explaining the process of the manufacturing method of ashless coal, and FIG. 2 is a schematic diagram which shows the solid-liquid separation apparatus for performing a gravity sedimentation method.

<Method of manufacturing ashless coal>

As shown in Fig. 1, the method for producing ashless coal includes a slurry preparation step (S1), an extraction step (S2), a separation step (S3), and a reformed coal acquisition step (S4).

Hereinafter, each process is demonstrated.

<Slurry Preparation Step (S1)>

Slurry preparation process (S1) is a process of mixing a solvent and coal and preparing a slurry.

As a solvent which melt | dissolves coal, generally monocyclic aromatic compounds, such as benzene, toluene, and xylene, polar solvents, such as N-methylpyrrolidone (NMP) and pyridine, etc. are used, but in this invention, 2 A non-hydrogen donor solvent mainly containing ring aromatics is used.

A non-hydrogen donor solvent is a coal derivative which is a solvent mainly containing the bicyclic aromatic refine | purified mainly from the dry product of coal. Since this non-hydrogen donor solvent is stable even in a heated state and excellent in affinity with coal, the ratio of the coal component extracted to a solvent (henceforth "extraction rate") is high, and it is also easy by distillation methods. It is a recoverable solvent. This recovered solvent can also be recycled for economical improvement.

Main components of the non-hydrogen donor solvent include naphthalene, methylnaphthalene, dimethylnaphthalene, trimethylnaphthalene, etc., which are bicyclic aromatics, and naphthalenes having other aliphatic side chains, and biphenyls or long chains. Alkylbenzenes having aliphatic side chains thereof are included.

It is preferable that a boiling point of a non-hydrogen donating solvent is 180-330 degreeC. If a boiling point is less than 180 degreeC, the required pressure in extraction process (S2) and the separation process (S3) will become high, and the loss by volatilization will increase in the process of recovering a solvent, and the recovery rate of a solvent will fall. Moreover, the extraction rate in extraction process S2 falls. On the other hand, when it exceeds 330 degreeC, separation of the solvent from the liquid part and non-liquid part mentioned later becomes difficult, and the recovery rate of a solvent falls.

As mentioned above, the extraction rate of coal can be improved by heat-extracting using a non-hydrogen donor solvent. Moreover, unlike a polar solvent, since a solvent can be easily collect | recovered, it is easy to circulate and use a solvent. Moreover, since expensive hydrogen, a catalyst, etc. do not need to be used, coal can be solubilized at low cost and ashless coal can be obtained, and economical efficiency can be aimed at.

As the coal used as the raw material of ashless coal (hereinafter also referred to as "raw coal"), it is preferable to use non-coking coal having little softening meltability, or nitro coal such as lignite or sub-bituminous coal. . By using such inexpensive coal, the ashless coal can be produced at a lower cost, and economical efficiency can be further improved. However, the coal used is not limited to these nitric coals, You may use coking coal as needed.

In addition, thermal coal here means coal, such as non-coking coal, a normal coal, and a low grade coal (brown coal, a sub-bituminous coal, etc.). In addition, the low quality coal is coal which contains 20% or more of water and is expected to be dehydrated. Such low-grade coals include lignite, attan, sub-bituminous coal and the like. For example, lignite includes Victorian, North Dakotatan, and Bergatan, and sub-bituminous coals include West Bankotan, Rain Snow, and Samarang. The low grade coal is not limited to the above-described examples, and all coals which contain a large amount of water and are expected to be dehydrated are included in the low grade coal referred to in the present invention.

Although the coal concentration with respect to a solvent also depends on the kind of raw material coal, the range of 10-50 mass% is preferable on a dry coal basis, and the range of 20-35 mass% is more preferable. When the coal concentration with respect to the solvent is less than 10% by mass, the proportion of the coal component extracted into the solvent relative to the amount of the solvent is small, which is not economical. The higher the coal concentration is, the more preferable it is. However, if it exceeds 50% by mass, the viscosity of the prepared slurry becomes high, and the movement of the slurry and separation of the liquid portion and the non-liquid portion in the separation step (S3) tend to be difficult.

<Extraction Step (S2)>

Extraction process (S2) is a process of cooling to 370 degrees C or less after extracting the slurry obtained by the said slurry preparation process for 20 minutes or less (it is also called a "heating" hereafter) at the temperature in 400-420 degreeC.

The heating temperature of the slurry in extraction process (S2) shall be in the range of 400-420 degreeC. If the heating temperature is less than 400 ° C., it is insufficient to weaken the bonds between the molecules constituting the coal, and when nitric coal is used as the raw material coal, the inventories of the anthracite obtained are up to the same degree as that of the coking coal. Can't increase On the other hand, when it exceeds 420 degreeC, the pyrolysis reaction of coal becomes very active, and since the recombination of the produced | generated pyrolysis radical occurs, extraction rate falls.

In the range of 400-420 degreeC of heating temperature, pyrolysis reaction advances too much as extraction time becomes long, a radical polymerization reaction advances, and an extraction rate falls. However, a relatively high extraction rate is maintained at an extraction time of 20 minutes or less. In addition, at the temperature of 370 ° C, the extraction rate becomes maximum when the extraction time is 30 minutes or more, and after that, the extraction rate does not change significantly over the extraction time of several hours, but the inventory temperature of the obtained ash is not increased. Therefore, in order to raise the stocking temperature of the obtained anthracite and to improve extraction rate, it is the most suitable condition to heat at 400-420 degreeC for 20 minutes or less, and to cool below 370 degreeC.

As for the minimum of the temperature at the time of cooling, 350 degreeC is preferable. If it is less than 350 degreeC, the solvent's dissolving power will fall, the reprecipitation of the coal component extracted once will arise, and the yield of ashless coal will fall.

In addition, in extraction process S2, as mentioned later, an extraction tank may be raised to 400-420 degreeC, for example, may be cooled immediately, and the lower limit of extraction time cannot be determined uniformly, but from an operational viewpoint of an extraction tank, The lower limit of the extraction time is preferably set to 1 minute. That is, in this case, the extraction time is preferably in the range of 1 to 20 minutes.

And after heating 20 minutes or less at the temperature of 400-420, it cools immediately to 370 degreeC or less. This is because if the cooling to 370 ° C. or less takes time, the extraction rate decreases by that amount.

Here, "cooling immediately" means cooling by performing a cooling process as soon as possible, for example, cooling by a cooling process as fast as possible until a slurry moves to the gravity settling tank mentioned later.

Since the extraction rate is higher as the heating time (extraction time) at a temperature of 400 to 420 ° C is shorter, in order to further improve the extraction rate, it is preferable to set the heating time (extraction time) to 15 minutes or less, and to 10 minutes or less. It is more preferable, and it is still more preferable to set it as 5 minutes or less. Furthermore, it is more preferable to cool to 370 degreeC or less immediately after extracting by heating up at 0-minute, ie, 400-420 degreeC temperature.

Moreover, in the range of the temperature of 400-420 degreeC, the temperature near 400 degreeC is preferable and it is preferable that it is 400 degreeC. The closer to 400 ° C, the higher the extraction rate.

In addition, when extracting in this extraction process (S2), the pyrolysis of coal produces | generates the aromatic-rich component which mainly mainly has an average boiling point [Tb50: 50% outflow temperature] 200-300 degreeC, and suitably It can use as a part of solvent.

It is preferable to perform extraction process (S2) in presence of inert gas.

This is because if it comes into contact with oxygen in the extraction step (S2), it may be ignited, which is dangerous, and the cost increases when hydrogen is used.

Although inexpensive nitrogen is preferably used as the inert gas used in the extraction step (S2), it is not particularly limited. In addition, although the pressure in extraction process S2 depends also on the temperature at the time of extraction and the vapor pressure of the solvent to be used, 1.0-2.0 MPa is preferable. When the pressure is lower than the vapor pressure of the solvent, the solvent is volatilized and cannot be confined to the liquid phase. In order to trap the extractable solvent in the liquid phase, a pressure higher than the vapor pressure of the solvent is required. On the other hand, if the pressure is too high, the cost of the equipment and the running cost are high, which is not economical.

<Separation step (S3)>

Separation process (S3) is a process of separating the slurry obtained by the said extraction process (S2) into a liquid part and a non-liquid part.

Here, a liquid part means the solution containing the coal component extracted from the solvent, and a non-liquid part means the slurry containing the coal component (coal containing ash, ie, coal) which is insoluble in a solvent.

Although it does not specifically limit as a method of separating a slurry into a liquid part and a non-liquid part in a separation process (S3), It is preferable to use the gravity sedimentation method.

As a method of separating a slurry into a liquid part and a non-liquid part, various filtration methods and a method by centrifugation are generally known. However, the method by filtration requires frequent replacement of the filtration aid, and in the method by centrifugation, blockage by undissolved coal components is likely to occur, and it is difficult to industrially perform these methods. Therefore, it is preferable to use the gravity sedimentation method which enables continuous operation of the fluid and is suitable for a large amount of processing at low cost. Thereby, the liquid part (henceforth "supernatant") which is the solution containing the coal component extracted in the solvent from the upper part of a gravity sedimentation tank, and the coal component insoluble in a solvent is contained from the lower part of a gravity sedimentation tank. The non-liquid part (henceforth a "solid content concentrate") which is a slurry can be obtained.

Hereinafter, an example of the gravity sedimentation method is demonstrated with reference to FIG. 1, FIG.

As shown in Fig. 2, in the solid-liquid separation apparatus 100, first, in the solid-liquid separation method 1, coal and a solvent of powdered coal, which is a raw material of ashless coal, are mixed in a coal slurry preparation tank 1 to prepare a slurry. It prepares (slurry preparation process (S1)]. Next, the slurry is supplied to the preheater 3 by the pump 2 from the coal slurry preparation tank 1, and the slurry is heated to 400-420 degreeC. Then, the heated slurry is supplied to the extraction tank (extractor) 4 and heated at 400 to 420 ° C. or less for 20 minutes while stirring with the stirrer 10, and then immediately cooled to 370 ° C. or less by the cooler 7 [ Extraction step (S2)]. Moreover, in order to cool immediately, it is preferable to provide a cooling mechanism in the extraction tank 4. In addition, "20 minutes or less" here is the sum total of the heating time in the preheater 3 and the extraction tank 4, and immediately after starting heating in 400-420 degreeC in the preheater 3, it is 370 degreeC immediately. It is time until it cools below. Then, the slurry subjected to this extraction treatment is supplied to the gravity settling tank 5, the slurry is separated into a supernatant and a solid concentrate (separation step (S3)), and the solid concentrate concentrated on the bottom of the gravity settling tank 5 is solid. At the same time, the upper supernatant is discharged to the filter unit 8 by a predetermined amount.

Here, in the gravity sedimentation tank 5, in order to prevent re-precipitation of the solute eluted from the coal of the raw material, it is preferable to maintain at 350 to 370 ° C., that is, the temperature at which the slurry is cooled and then cooled, and the pressure is It is preferable to set it as the pressure range of 1.0-2.0 MPa.

In the gravity settling tank 5, the time to maintain the cooled temperature is a time required for separating the slurry into a supernatant and a solid concentrate, and is generally 60 to 120 minutes, but is not particularly limited.

In addition, although the component soluble in the solvent accompanying solid content concentrate can be collect | recovered by increasing the number of gravity sedimentation tanks 5, in order to collect | recover efficiently, it is suitable to arrange | position the gravity sedimentation tank 5 in two stages. .

And the supernatant liquid discharged | emitted from the gravity settling tank 5 is filtered by the filter unit 8 as needed, and is collect | recovered by the supernatant liquid container 9.

As described below, the solvent is separated and recovered from the liquid portion and the non-liquid portion using a distillation method or the like to obtain ashless ash, which is reformed coal, from the liquid portion (reformed coal acquisition step S4). . In addition, as needed, concentrated by-product coal of ash, which is modified coal, can be obtained from the non-liquid portion.

<Reformed coal acquisition process (S4)>

The reformed coal acquisition step S4 is a step of separating the solvent from the liquid portion separated in the separation step S3 to obtain ashless coal, which is reformed coal (anthracite acquisition step).

As a method of separating the solvent from the supernatant (liquid portion), a general distillation method or an evaporation method (spray drying method, etc.) can be used, and the separated and recovered solvent is circulated to the coal slurry preparation tank 1 (see FIG. 2). Can be used repeatedly. By separating and recovering the solvent, an ashless coal substantially free of ash can be obtained from the supernatant.

This ashless coal contains little ash, no moisture, and exhibits a higher calorific value than the raw coal. In addition, the softening meltability, which is a particularly important quality as a raw material of steel coke, is greatly improved, and shows much better performance (fluidity) than raw coal. Therefore, this ashless coal can be used as a coal blend of a coke raw material. Moreover, it can also be used as a coal blend by mixing with by-product coal.

In addition, if necessary, in addition to obtaining ashless coal in the reformed coal acquisition step (S4), a by-product coal as modified coal may be produced by separating the solvent from the non-liquid portion separated in the separation step (S3). Good (byproduct coal acquisition process).

As a method of separating the solvent from the solid concentrate (non-liquid portion), a general distillation method or an evaporation method can be used, similarly to the ashless coal acquisition step described above, and the solvent recovered by separation is prepared from a coal slurry preparation (1) (see FIG. 2). Can be used repeatedly. By-product separation | disassembly and collection | recovery can produce the by-product coal in which ash was concentrated from the solid content concentrate.

This by-product coal contains ash, but there is no moisture, and it has sufficient calorific value. Although it does not show this about softening meltability, when oxygen-containing functional group is separated, when used as a coal blend, it does not impair the softening meltability of the other coal contained in this coal blend. Therefore, this by-product coal can be used as a part of the coal blend of a coke raw material similarly to normal non-coking coal, and can also be used for various fuels, without making coke raw coal.

In addition, only ashless ash without ash from the liquid portion may be produced for the coke raw coal, only solvent is recovered from the non-liquid portion, and the by-product coal in which ash is concentrated may be discarded without recovery.

Although this invention is as above-mentioned, in the range which does not adversely affect each said process in carrying out this invention, the coal grinding process which grinds raw material coal, for example between or before and after each said process, Other processes, such as the removal process of removing unnecessary substances, such as a waste, and the drying process of drying the obtained ashless coal, may be included.

Next, an Example is given and the manufacturing method of the ashless coal which concerns on this invention is concretely demonstrated.

Example 1

In Example 1, when the extraction temperature in an extraction process is 370 degreeC, the change of the softening meltability (softening fluidity), stocking temperature, etc. of raw material coal and the ashless coal obtained by this raw material coal is investigated ( Experimental Example 1).

4 times (20 kg) of solvent [1-methylnaphthalene (new) with respect to 5 kg of each raw coal, using the hard coal coal A, the hard coal coal B, and the sub-bituminous coal C which are the industrial analysis values and elemental analysis values shown in Table 1 as raw material coal. Nittetsu Kagakusha Co., Ltd.] was mixed to prepare a slurry. The slurry was pressurized with 1.2 MPa of nitrogen and extracted under conditions of 370 ° C. for 1 hour in an internal volume of 30 L of autoclave. The slurry is separated into a supernatant and a solid concentrate in a gravity settling tank maintained at the same temperature and pressure, the solvent is separated and recovered by distillation from the supernatant, ashless coal a from hard coal coking A, ashless coal b from hard coking coal B, From the sub-bituminous coal C, an ashless coal c was obtained. These industrial analysis values and elemental analysis values are shown in Table 1.

Next, the Gigeller softening flow test prescribed | regulated to JISM 8801 was performed about strong coking coal A and B, C, anthracite a, b, and c.

The test results are shown in Table 1. 3 is a graph which shows the Gisele curve by a Gisele softening flow test.

As shown in Table 1, ashless coals a, b, and c do not contain water, and the ash content is only a fraction of that of raw coal. Moreover, it turned out that it shows high calorific value compared with raw material coal. Although the oxygen concentration in the sub-bituminous coal C is high as 15% or more, and the ashless c is also reduced by about 10%, the oxygen concentration is maintained relatively high.

Here, as a result of the Gisler softening flow test, when the stocking temperature of the raw coal is focused, the coking coals A and B are 496 ° C and 483 ° C, respectively, whereas the sub-bituminous coal C is low in the inventory temperature of 445 ° C. Sub-bituminous coal C cannot be used as a raw coal of steel coke because the soft melt (softening fluidity) state for firmly fixing the raw coal is important for obtaining coke strength.

Moreover, from the values of the highest fluidity of FIG. 3 and Table 1, it shows that for softening meltability, for the ashless coals a, b, and c obtained from these raw coals, the good softening meltability far exceeding each raw material coal is shown. Could know.

However, when paying attention to the stocking temperature of the obtained anthracite coal, the anthracite a and b obtained from the coking coal A and B are 508 degreeC and 488 degreeC, and they solidify at the temperature higher than the coking coal A and B which are raw materials coal, The ashing temperature of ashless c, obtained from C, is higher than that of sub-bituminous coal, C, but relatively low at 463 ° C.

Here, when anthracite c is added to the steelmaking coke raw coal and coked as a coal blend, the ash coal c is solidified at 463 ° C. while the coking coal maintains fluidity, thereby impairing the fluidity of the entire coal blend. This results in lowering the strength of the obtained coke.

From the above results, it was found that when nitric coal such as sub-bituminous coal was used as the raw material coal, even if an ashless coal was obtained under the above conditions, the ashless coal was not particularly excellent as the raw coal of steel coke.

In addition, when coking coal (or coking coal) is used as the raw material coal, the obtained anthracite exhibits softer melting performance than that of the raw material coal, and can be used as raw coal for steel coke. However, since coking coal is expensive, raw coal costs are reduced. Can't.

Example 2

In Example 2, the relationship between the extraction temperature when the sub-bituminous coal C used in Example 1 was extracted and the ashing temperature of the ashless c obtained from the sub-bituminous coal C was investigated (Experimental Example 2).

FIG. 4 shows the relationship between the extraction temperature when the sub-bituminous coal C is extracted for 1 hour (60 minutes) as the raw coal and the obtained ash-free c stock.

In addition, about the method of obtaining an ashless coal, it carried out according to Example 1 except the extraction temperature.

As shown in FIG. 4, when the extraction temperature exceeds about 360 ° C., the inventory temperature of the ashless coal c increases with the increase of the extraction temperature, and at 400 ° C., the inventory temperature becomes about 490 ° C., It was found that the temperature rose to the same degree as the stocking temperature of the coking coal. And when it exceeds 400 degreeC, a stock temperature rises further. Therefore, it turned out that the reoxidation temperature of the obtained ashless coal becomes high by raising the temperature which extracts coal to 400 degreeC or more.

As a result, it was found that when pyrocarbon such as sub-bituminous coal was used as the raw material coal, the ashless coal obtained could be used as raw coal for steelmaking coke by setting the extraction temperature to 400 ° C or higher.

Example 3

In Example 3, the relationship between extraction temperature, extraction time, and extraction rate when the sub-bituminous coal C used in Example 1 was extracted was examined (Experimental Example 3).

Sub-bituminous coal C is extracted at a preheater up to 370 ° C., 400 ° C. and 420 ° C. as the extraction temperature, and after a certain time is retained in the extractor. Illustrated. In addition, in the experiment of 420 degreeC, since the time which heated up from 400 degreeC to 420 degreeC in the preheater was 8 minutes, in FIG. 5, the extraction time of 400 degreeC to 420 degreeC was shown as the time which added 8 minutes in the preheater. .

In addition, about the method of obtaining an ashless coal, it carried out according to Example 1 except extraction temperature and extraction time.

In addition, the extraction rate of coal was calculated | required from the quantity of the solid by-product coal which isolate | separated.

Specifically, it calculated | required by the formula (raw material coal by-product coal) / raw material coal x100. In addition, raw material coal and by-product coal are anhydrous anthracite-based.

Here, the extraction time is a temperature holding time until the temperature is maintained at a predetermined temperature and then cooled to 370 ° C. or lower, and the extraction time 0 is immediately performed without raising the temperature after the temperature is raised to the predetermined temperature. This is the case when it cools.

As shown in FIG. 5, at the extraction temperature of 370 degreeC, extraction time acquired the largest extraction rate in 30 minutes, and even after several hours of extraction time, the extraction rate of coal did not change significantly. On the other hand, at the temperature of 400 degreeC and 420 degreeC, when it exists in the temperature range where the thermal decomposition of coal rapidly rises and maintains a comparatively long time temperature, the fall of extraction rate will be remarkable by the repolymerization reaction of the radical which arises from thermal decomposition of coal, etc. It was found that the long-term temperature maintenance is uneconomical.

In addition, since it is known that pyrolysis violently and extraction rate falls at the temperature exceeding 420 degreeC, experiment was abbreviate | omitted here.

Specifically, at the extraction temperature of 400 ° C., there was almost no change at the extraction time of 0 to 20 minutes, and an extraction rate of about 60% or more was obtained. However, when the extraction time reached 60 minutes, the extraction rate was reduced to about 50%. Moreover, even if it raises extraction temperature to 420 degreeC, it turned out that comparatively high extraction rate (about 52% or more) is maintained in the extraction time within 20 minutes.

In general, if the extraction rate is about 52% or more, it can be said to be a relatively high extraction rate.

As a result, it was found that ashless coal was obtained with high efficiency if the extraction temperature was within 400 minutes at 400 to 420 ° C until cooling to 370 ° C or less.

In addition, the stocking temperature of the ashless coal obtained at 400 degreeC and 0 minutes of extraction conditions was 483 degreeC, and it was 490 degreeC in 10 minutes of extraction conditions. In addition, the stocking temperature of the ashless coal obtained at 420 degreeC and 0 minutes of extraction conditions was 487 degreeC, and it was 486 degreeC in 22 minutes of extraction conditions. From this, the ashing temperature of the anthracite obtained by heating nitric coal, such as sub-bituminous coal, at a temperature of 400 to 420 ° C. for 20 minutes or less, and then cooling to 370 ° C. or less is comparable to the above-mentioned stocking temperature of coking coal. In addition to the raw coal of the molten coke, it can be said that the mixed coal does not impede the fluidity of the coking coal contained in the mixed coal, and does not impair the fluidity of the entire coal mixture.

On the other hand, at an extraction temperature of 370 ° C., only a stocking temperature of about 460 ° C. can be obtained, and even though the extraction rate is high, as described above, the raw coal of steel coke is not particularly excellent.

As a result of the results of Examples 1 to 3, when the raw materials such as inexpensive non-coking coal such as coking coal are used as raw materials, the conditions for obtaining high ashing temperature and high efficiency ashless coal are 400 to 420 ° C as the extraction temperature. After heating up 20 minutes or less, and cooling to 370 degrees C or less, Preferably, the time (extraction time) to hold at 400-420 degreeC is 15 minutes or less, More preferably, it is 10 minutes or less, and also extraction time. It turned out that it is so preferable that it is short.

And the ashless coal obtained in this way can be added to the raw coal of steelmaking coke, and it can be said that it does not deteriorate the strength of coke also as a coal blend.

In addition, although Examples 2 and 3 show the case where nitric coal is used as the raw material, when the coking coal (strong coking coal) is used as the raw material, the obtained anthracite is higher in quality than the anthracite based on the thermal nitric coal. Moreover, it becomes a higher quality than coking coal which is raw material coal. Therefore, coking coal may be used as a raw material when producing a higher quality ashless coal. However, in the case where the cost reduction of the coke raw coal is important, it is preferable to use inexpensive nitric coal as a raw material.

As mentioned above, although the best embodiment and Example were shown and demonstrated in detail about the manufacturing method of the ashless coal which concerns on this invention, the meaning of this invention is not limited to the above-mentioned content, The scope of a claim describes a claim It must be widely interpreted on the basis of It goes without saying that the contents of the present invention can be widely modified, changed, etc. based on the above description.

Claims (5)

It is a manufacturing method of ashless coal used for raw coal of steel coke, A slurry preparation step of preparing a slurry by mixing a solvent and coal; An extraction step of extracting the slurry obtained in the slurry preparation step at a temperature of 400 to 420 ° C. for 20 minutes or less, and cooling to 370 ° C. or less, A separation step of separating the slurry obtained in the extraction step into a liquid part and a non-liquid part; And a reformed coal obtaining step of separating the solvent from the liquid portion separated in the separation step to obtain ashless coal, which is reformed coal. The ashless coal according to claim 1, wherein in addition to obtaining ashless coal in the reformed coal acquisition step, the by-product coal as modified coal is obtained by separating the solvent from the non-liquid portion separated in the separation process. Method of preparation. The ash extraction method according to claim 1 or 2, wherein in the extraction step, the slurry obtained in the slurry preparation step is extracted by heating up at a temperature of 400 to 420 ° C and immediately cooled to 370 ° C or less. Method of preparation. The method for producing ashless coal according to claim 1 or 2, wherein the coal is nitric coal. The method for producing ashless coal according to claim 3, wherein the coal is nitric coal.

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