JP2009013221A - Method of manufacturing modified coal and manufacturing method of coke - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of reforming low-grade coal containing a large amount of oxygen atoms without generating a large amount of water, and to provide a method of manufacturing coke for iron-making by using the same. <P>SOLUTION: A method of manufacturing modified coal by treating low-grade coal with heavy oils comprises: a deoxidization step of subjecting low-grade coal containing a large amount of oxygen atoms to a heating treatment, thereby decreasing the oxygen content down to ≤15 mass%; and a modifying step of heating the low-grade coal after deoxidization together with heavy oils at a temperature of 300-500°C, thereby causing the decomposition product of heavy oils to adhere to the surface of the low-grade coal. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention modifies low-grade coal containing a large amount of oxygen atoms and is suitable for the production of coke for iron making, that is, a method for producing artificial caking coal, and the reformed coal of the blended coal. The present invention relates to a method for producing coke using as a raw material.

  Iron coke used in steelworks blast furnaces is a blended coal by mixing (compounding) dozens of brands including caking coal belonging to bituminous coal, and the blended coal is heated to 1000-1400 ° C in the coke oven. It is manufactured by heating around 20 hours and performing high temperature carbonization. In recent years, the caking coal necessary for producing iron-making coke is actually lacking, and from this, the use of low-grade coal has been studied. Low-grade coal is a coal with a ratio of aromatic carbon to total carbon of 50-60%, and there are many reserves and many coal types with low ash and sulfur content, but there is a lot of moisture and a calorific value. There is a problem that it is low, has a high oxygen content, and is not dense, so that it is easily pulverized and easily ignites.

Therefore, low-grade coals such as subbituminous coal, lignite, lignite, and peat are reformed at 400 to 450 ° C. using a solvent in a hydrogen atmosphere as shown in Patent Document 1 and Patent Document 2, and are graded. And a technique for utilizing this for coke production is disclosed. In Patent Document 3, a mixture of low-grade coal and heavy hydrocarbon is heat-treated at 300 to 500 ° C., and distilled under conditions of a tower bottom temperature of 250 to 320 ° C. and a pressure of 40 mmHg or less. Techniques for obtaining charcoal and tar oil are disclosed. Furthermore, Patent Document 4 discloses a technique for obtaining a reformed coal and a light oil fraction by liquid phase decomposition of low-grade coal at 400 to 450 ° C.
JP 53-104603 A Japanese Patent Laid-Open No. 55-69691 JP 58-217593 A Japanese Patent No. 3198306

  However, since Patent Document 1 and Patent Document 2 use a method of reforming low-grade coal by heat treatment in a hydrogen atmosphere, oxygen atoms contained in a large amount in hydrogen and low-grade coal ( About 27% by mass) to form a large amount of water. For this reason, these technologies are low in the amount of reformed coal acquired and inefficient, and are equipped with an oil / water separator for removing a large amount of generated water, and an advanced level for removing oil mixed in moisture. In addition to having to install a large wastewater treatment facility, a large amount of hydrogen gas is required, so it is necessary to increase the size of the gas compression / circulation facility.

  Further, in Patent Document 3 and Patent Document 4, oxygen atoms of low-grade coal react with hydrogen atoms in the solvent (heavy oil), or oxygen atoms and hydrogen atoms contained in the low-grade coal react. Since a large amount of water is generated, the product can be obtained in a mixed state of reformed coal, solvent (heavy oil) and water. There was a problem of becoming larger.

  Therefore, the present invention was developed in view of the above problems, a method for reforming low-grade coal containing a large amount of oxygen atoms without generating a large amount of water, and for iron making using the same It aims at providing the manufacturing method of coke.

  As a result of intensive studies to achieve the above object of the present invention, the present invention provides a method for producing modified coal by treating low-grade coal with heavy oils. The deoxidation step of reducing the oxygen content to 15% by mass or less, and heating the low-grade coal after deoxidation together with heavy oils at a temperature of 300 to 500 ° C. And a reforming step of attaching a decomposition product of heavy oils to a modified coal production method.

  In the present invention, the deoxidation step comprises drying the low-grade coal, then heating it in an inert gas atmosphere or a reducing gas atmosphere at a temperature range of more than 400 ° C. and 800 ° C. or less, and further oxidizing gas. The step of heating in a temperature range of 800 to 1200 ° C. under an atmosphere, the deoxidation step is performed by lyophilizing or supercritically drying low-grade coal, and then in an inert atmosphere or a reducing atmosphere, The process of heating in a temperature range of 1200 ° C., the low-grade coal after deoxidation is a porous body, the reforming step is performed in a hydrogen-containing atmosphere, and after deoxidation Supporting a metal and / or a metal compound on the low-grade coal can provide a more preferable solution.

  In addition, the present invention proposes a method for producing coke, characterized in that the blended coal containing the modified coal obtained by the above production method is charged into a coke oven and heated and distilled at a temperature of 1000 to 1200 ° C. .

In the present invention having the above-described configuration, the low-grade coal as the raw coal is deoxidized before the reforming so that the oxygen content is 15% by mass or less. Does not generate a large amount of water during the quality treatment process. As a result, low-grade coal can be reformed efficiently, and equipment such as oil-water separators and wastewater treatment facilities can be omitted. Charcoal and steelmaking coke can be obtained.
In addition, since the low-grade coal after deoxidation is porous, it can adhere and retain a large amount of heavy components in the pores, and also has high adhesion, thus improving the coke strength. be able to.

  In the present invention, the raw coal to be reformed is a low-grade coal having a high oxygen atom content such as subbituminous coal, lignite, lignite, and peat. As the brown coal, Australian-made Yarune coal, Moel coal, Royan coal and the like are suitable. In the present invention, biomass raw materials such as wood and coconut shells can be used in addition to or in place of the raw coal.

  In the method for producing modified coal of the present invention, the low-grade coal raw material is heated to reduce the oxygen content to 15% by mass or less, and the low-grade coal after the deoxidation step is used in heavy oils. It is characterized by being subjected to a reforming step of heating and attaching the decomposition products of heavy oils, that is, heavy components.

  First, the deoxidation step will be described. There are two methods for the deoxidation step. One of them is a low-grade coal raw material that is dried by ordinary hot air (about 100 to 200 ° C.), etc., and then inert gas such as nitrogen gas, or the self-generated gas generated by the low-grade coal itself when heated. In a reducing gas atmosphere, heated to a temperature of more than 400 ° C. and not more than 800 ° C., preferably about 500 to 700 ° C., and then heated to a temperature of 800 to 1200 ° C. in an oxidizing gas atmosphere. By reacting with. In this method, oxygen atoms in the low-grade coal are released as carbon monoxide and carbon dioxide by heating, so that the oxygen content in the low-grade coal can be reduced to 15% by mass or less.

  Here, the reason why the oxygen content in the low-grade coal is reduced to 15% by mass or less is due to a decrease in the reactivity of the low-grade coal, particularly a decrease in the thermal reactivity starting from oxygen atoms. Thus, the generation of water can be reduced in the reforming step after the deoxidation step.

  Further, as the oxidizing gas, steam, carbon dioxide, oxygen and a mixed gas thereof are used, and these are used as a low-grade coal raw material and a reaction furnace such as a fixed bed furnace, a tunnel furnace, a rotary furnace, and a fluidized bed furnace. React in. In the present invention, the reason for performing the treatment with the oxidizing gas is to react the carbon atoms constituting the low-grade coal raw material with the oxygen atoms contained in the oxidizing gas, and release them mainly in the form of carbon monoxide. This is because the part of the reacted carbon atom is used as a pore, that is, it is made porous.

  Further, low-grade coal is heated at a temperature of more than 400 ° C. and not more than 800 ° C. in an inert gas or reducing gas atmosphere such as nitrogen gas. On the other hand, if it exceeds 800 ° C., the shrinkage of the low-grade coal starts, that is, the orientation and crystallization of the low-grade coal begins, and the reactivity in the subsequent reaction decreases. It is for doing. Moreover, heating at 800-1200 degreeC in oxidizing gas atmosphere is for accelerating | stimulating porosity.

  Further, when sub-bituminous coal is used as the low-grade coal, a part thereof softens and melts during heating, and thus it is preferable to modify (oxidize) before heating. This modification (oxidation) is usually caused by raising the temperature to 100 to 300 ° C. in the air, but can also be performed by applying a gas having an oxidizing power such as oxygen or nitrogen dioxide.

Next, the deoxidation step of the present invention is a method in which low-grade coal is freeze-dried or supercritically dried and then heated to 300 to 1200 ° C. in an inert atmosphere or a reducing atmosphere, in addition to the above-described method. May be.
Here, freeze-drying is a drying method in which, for example, in the case of moisture drying, the moisture is changed to gas (water vapor) after being cooled to −20 ° C. to −50 ° C. and then converted to gas (water vapor). This method is also called vacuum lyophilization because it is a method of reducing the boiling point of water by reducing the boiling point of water. In supercritical drying, a wet substance to be dried is heated and pressurized in a pressure vessel to bring the liquid (water, alcohol, etc.) contained therein into a supercritical state and then dried. Is the method.

  The reason for using these drying methods is that in normal hot-air drying, when lignite with pores in the raw materials such as lignite, lignite, and peat is dried, the lignite contracts due to the capillary force of the water embedded in the pores. The pore structure may be destroyed. In this respect, since supercritical drying is a drying method in which a gas-liquid interface does not appear at the time of drying, moisture is removed while leaving a pore structure, and further, carbonization, that is, porous carbon material by firing Is advantageous.

  Low-grade coal after freeze-drying or supercritical drying is charged into firing furnaces such as fixed-bed furnaces, tunnel furnaces, rotary furnaces, fluidized bed furnaces, etc. It heats to the temperature of about 300-1200 degreeC under a reducing atmosphere, such as 400-800 degreeC preferably.

The low-grade coal after the deoxidation step becomes porous because the portion from which oxygen atoms are released becomes pores. Low grade coal already de-acid obtained in this way, the specific surface area measured by the BET method using nitrogen gas 300~1500m ² / g, preferably about about 600~1200m ² / g porous coal It is preferable that This is because if the specific surface area is too small, the adhesion between the low-grade coal and the decomposition products of heavy oils will be weak, and the strength when coke is produced using this will become insufficient. . On the other hand, when the specific surface area of the low-grade coal is too large, pores having small pore diameters that do not contain decomposition products increase, and the coke strength decreases.

Next, the reforming process will be described.
In the reforming process, the low-grade coal after deoxidation (hereinafter referred to as “porous carbon material”) is heated in heavy oil (petroleum heavy oil or coal heavy oil), A very heavy component such as coke, carbon, or a precursor thereof generated by thermal decomposition of heavy oil enters and is absorbed in the pores of the porous carbon material.

  In this reforming step, the porous carbon material and the heavy oil are heated to a temperature of about 300 to 500 ° C. in an inert atmosphere or a reducing atmosphere, and particularly in a reducing atmosphere mainly composed of hydrogen gas. It is preferable to heat to a temperature of 380 to 460 ° C. This is because the pyrolysis of heavy oil is a kind of disproportionation reaction, so that coke or carbon, which is a heavy component, is produced, while light components are also produced. It is presumed that the viscosity of the component is lowered and the movement of a very heavy component such as coke, carbon or a precursor thereof is facilitated, and the penetration and the adsorption are easily promoted into the pores.

  This reforming step can be suitably performed by a complete mixing tank type such as a fixed bed, a moving bed, a suspension (slurry bed), a boiling bed, and the like, as well as a suspension bed and a boiling bed.

  The amount of the decomposition product (heavy content) attached to the porous carbon material is preferably 5 times (mass ratio) or less of the porous carbon material. This is because if the amount of decomposition products deposited becomes too large, the physical properties of oil coke will not change, and it will not be possible to use as raw coal.

  Here, petroleum heavy oil is heavy oil and super heavy oil related to petroleum refining, and heavy oil is, for example, crude oil, petroleum-based atmospheric distillation residue, vacuum distillation residue, contact Residual oil such as cracked residual oil or oil sand oil, oil shale oil, etc., and super heavy oil, for example, Maya from Mexico, Athabasca oil sand bitumen from Canada, Cold Lake oil sand bitumen, Venezuela It is a kind of oil such as Orinocotar, Celonegro, Zuata, Batchachero, Boscan, and Marim produced in Brazil. The coal-based heavy oil is a heavy fraction that is fractionated by distillation of coal tar generated from a coke oven, such as creosote oil, anthracene oil, and pitch. There is also a heavy fraction of liquefied oil obtained by liquefaction of coal.

  In the present invention, after attaching the decomposition product to the porous carbon material as described above, the excess oil is separated by using a method such as normal filtration, centrifugation, distillation, etc. Charcoal.

  The reformed coal obtained in this way may be used as raw coal for blended coal, but by using a modified coal with improved properties by further modification and heat treatment. Also good. In particular, when the decomposition product more than 5 times adheres and adsorbs to the porous carbon material, this modification treatment or heat treatment is effective.

  The modification treatment is a method of heating to about 150 to 300 ° C. in the air, and the heat treatment is a method of heating to about 300 to 600 ° C. in an inert atmosphere or a reducing atmosphere. Moreover, in the state of pressure reduction, since a part of decomposition product volatilizes, what is necessary is just to heat at about 200-400 degreeC.

  Prior to the reforming step, the porous carbon material is preferably loaded with a metal such as iron or an iron compound and / or a metal compound (hereinafter referred to as “metals”). This is because the decomposition of heavy oils is promoted by the action of the supported metals, and it is efficiently converted into a light fraction, and one of the decomposition products of heavy substances, coke and carbon. Alternatively, the heavy components such as their precursors are sufficiently adhered and held in the pores in the porous carbon material, and high quality modified coal can be obtained.

  In addition, iron, cobalt, nickel, etc. can be used as a metal, and it is preferable to use iron especially from cost and the ease of handling. Further, as the metal compound, nitrates such as iron, cobalt, nickel, hydrochlorides, sulfates, acetates, and the like can be used.

  In addition, the loading of metals on the porous carbon material may be performed in an undried state or after the porous carbon material is once dried, and in an undried state from the viewpoint of energy saving. Is preferred.

  Next, a method for producing coke using the modified coal obtained as described above will be described. The reformed coal that has undergone the above-mentioned treatment is subjected to particle size adjustment such as pulverization and granulation, if necessary, and is introduced into a blending tank of a coke oven in the same manner as other raw coals to adjust the blended coal. The blended charcoal is charged into a coke oven kiln with a charcoal car and dry-distilled at 1000 to 1200 ° C. for about 20 hours under a natural gas reducing atmosphere. Then, it extrudes from a kiln with an extruder, cools to normal temperature with a CDQ equipment, and is set as iron-making coke.

Example 1
a. Deoxidation treatment step: Lignite with volatile content: 40 to 50 mass%, ash content: 0.5 mass% (component composition: carbon 67.1 mass%, hydrogen 4.3 mass%, nitrogen 0.9 mass%, sulfur 0 .2 mass%, oxygen 27.0 mass%) in a nitrogen gas atmosphere at 105 ° C. for 1 hour, and then placed in a SUS rotary kiln furnace with an inner diameter of 600 mm, under a nitrogen gas flow from room temperature to 5 ° C. / The temperature was raised to 600 ° C. in minutes and kept at 650 ° C. for 30 minutes for carbonization, then the flow gas was switched to water vapor and the temperature was raised to 900 ° C. at 3 ° C./min. After maintaining at 900 ° C. for 10 hours, the mixture was cooled to room temperature to obtain a fired product (porous carbon material).
The properties of the fired product (porous carbon material) obtained are shown in Table 2. Then, it was immersed in a 1N aqueous iron nitrate solution for 3 hours, and 5 mass% Fe was supported and dried.
b. Next, 10 kg of the fired product (porous carbon material) and 15 kg of vacuum residual oil were put into an induction stirring autoclave having an internal volume of 50 liters, and in a hydrogen atmosphere (pressure: 11.8 MPa (120 Kg / cm ² G) ) At 430 ° C. for 60 minutes, and then the reaction product was taken out from the autoclave, and oil having a boiling point of less than 538 ° C. was removed by distillation under reduced pressure to obtain modified coal.
A blended coal was prepared by adding a base blended coal of caking coal prepared by mixing four modified (A to D coal) coals (coking coal for coke) shown in Table 1 to 10% by mass of this modified coal. . And this coal mix was dry-distilled in a 1100 degreeC coke oven for 18 to 20 hours, and coke was obtained. The filling density of the blended coal was 0.76 kg / liter. The drum strength (DI ³⁰ ₁₅ ) of the produced coke was measured according to JIS K2151. The results are shown in Table 2.

(Example 2)
a. Deoxidation treatment step After lyophilizing the same lignite as in Example 1, it was placed in a SUS rotary kiln furnace with an inner diameter of 600 mm and heated from room temperature to 600 ° C. at a rate of 5 ° C./min under a nitrogen gas flow. It was kept at 60 ° C. for 60 minutes and fired to make it porous. The properties of the fired product (porous carbon material) obtained are shown in Table 2.
b. Next, 5 kg of the fired product (porous carbon material) and 20 kg of pitch are put into an induction-stirring autoclave having an internal volume of 50 liters, and under a nitrogen atmosphere (initial pressure: 0.98 MPa (10 Kg / cm ² G) ) At 380 ° C. for 60 minutes. Thereafter, the reaction product was taken out from the autoclave and heat-treated at 430 ° C. for 30 minutes under a nitrogen gas flow to remove light components to obtain modified coal.
The blended coal is prepared by adding the base blended coal of caking coal prepared by mixing the four coals (A to D coal) shown in Table 1 (coking coal for coke) to 10% by mass of this modified coal. The drum strength (DI ³⁰ ₁₅ ) of coke was measured in the same manner as in Example 1. The results are shown in Table 2.

(Example 3)
a. Deoxidation treatment step After squeezing the same lignite as in Example 1 and dehydrating it, placing it in a SUS rotary kiln furnace with an inner diameter of 600 mm, raising the temperature from room temperature to 450 ° C. at a rate of 5 ° C./min. And baked by holding at 450 ° C. for 30 minutes. The properties of the fired product (porous carbon material) obtained are shown in Table 1.
b. Next, 10 kg of the fired product (porous carbon material) and 15 kg of pitch are put into an induction-stirring autoclave having an internal volume of 50 liters, and in a nitrogen atmosphere (initial pressure: 0.98 MPa (10 Kg / cm ² G) ) Was held at 400 ° C. for 60 minutes. Thereafter, the reaction product was taken out from the autoclave, and oil having a boiling point of less than 538 ° C. was removed by distillation under reduced pressure to obtain modified coal.
The blended coal is prepared by adding the base blended coal of caking coal prepared by mixing the four coals (A to D coal) shown in Table 1 (coking coal for coke) to 10% by mass of this modified coal. The drum strength (DI ³⁰ ₁₅ ) of coke was measured in the same manner as in Example 1. The results are shown in Table 2.

Example 4
a. Deoxidation treatment step After squeezing and dehydrating the same lignite as in Example 1, it is placed in a SUS rotary kiln furnace with an inner diameter of 600 mm and heated from room temperature to 350 ° C. at a rate of 5 ° C./min under a nitrogen gas flow. And baked at 350 ° C. for 30 minutes. Thereafter, it was immersed in a 1N aqueous iron nitrate solution for 3 hours to support 5% by weight of Fe and then dried. The properties of the fired product (porous carbon material) obtained are shown in Table 1.
b. Next, 10 kg of the fired product (porous carbon material) and 15 kg of pitch are put into an induction-stirring autoclave having an internal volume of 50 liters, and in a nitrogen atmosphere (initial pressure: 0.98 MPa (10 Kg / cm ² G) ) Was held at 400 ° C. for 60 minutes. Thereafter, the reaction product was taken out from the autoclave, and oil having a boiling point of less than 538 ° C. was removed by distillation under reduced pressure to obtain modified coal.
The blended coal is prepared by adding the base blended coal of caking coal prepared by mixing the four coals (A to D coal) shown in Table 1 (coking coal for coke) to 10% by mass of this modified coal. It was measured coke drum strength ^(DI _{30 15)} in the same manner as in example 1. The results are shown in Table 2.

(Comparative Example 1)
The same lignite (dried product) as in Example 1 was mixed with a base coal blend consisting of the formulations shown in Table 1, and subjected to dry distillation in a coke oven at 1100 ° C. for 18 to 20 hours to obtain coke. The drum strength (DI ³⁰ ₁₅ ) of the obtained coke was measured according to JIS K2151, and the results are shown in Table 2.

(Comparative Example 2)
The base blended charcoal composed of the blend shown in Table 1 was filled so that the packing density was 0.76 kg / liter, and was subjected to dry distillation in a coke oven at 1100 ° C. for 18 to 20 hours to obtain coke. The drum strength (DI ³⁰ ₁₅ ) of the obtained coke was measured according to JIS K2151, and the results are shown in Table 2.

(Comparative Example 3)
After vacuum drying the same lignite as in Example 1, 10 kg of lignite and 15 kg of vacuum residual oil were put into an induction stirring autoclave having an internal volume of 50 liters, and in a hydrogen atmosphere (pressure: 11.8 MPa (120 Kg / cm ² G) Was kept at 430 ° C. for 60 minutes, and then the reaction product was taken out from the autoclave, and oil having a boiling point of less than 538 ° C. was removed by distillation under reduced pressure to obtain modified coal.
A base coal blend of caking coal composed of the blend shown in Table 1 was added to 10% by mass of the modified coal to prepare a blend coal. And this coal mix was dry-distilled in a 1100 degreeC coke oven for 18 to 20 hours, and coke was obtained. The drum strength (DI ³⁰ ₁₅ ) of the prepared coke was measured according to JIS K2151. The results are shown in Table 2.

(Comparative Example 4)
The same lignite as in Example 1 was vacuum-dried and then heat-treated at 280 ° C. Next, 10 kg of heat-treated lignite and 15 kg of vacuum residual oil were put into an induction stirring autoclave having an internal volume of 50 liters, and 430 ° C. for 60 minutes in a hydrogen atmosphere (pressure: 11.8 MPa (120 Kg / cm ² G)). Thereafter, the reaction product was taken out from the autoclave, and oil having a boiling point of less than 538 ° C. was removed by distillation under reduced pressure to obtain modified coal.
A base coal blend of caking coal composed of the blend shown in Table 1 was added to 10% by mass of the modified coal to prepare a blend coal. And this coal mix was dry-distilled in a 1100 degreeC coke oven for 18 to 20 hours, and coke was obtained. The drum strength (DI ³⁰ ₁₅ ) of the prepared coke was measured according to JIS K2151. The results are shown in Table 2.

(Comparative Example 5)
The same lignite as in Example 1 was vacuum-dried, then placed in a SUS rotary kiln furnace with an inner diameter of 600 mm, heated from room temperature to 1250 ° C. at a rate of 5 ° C./min under a nitrogen gas flow, and heated at 1250 ° C. for 60 minutes. Hold and fired. Table 2 shows the properties of the obtained fired product.
Then, the fired product 5kg and pitch 20 kg, was added to induce stirring type autoclave having an internal volume of 50 liters in a nitrogen atmosphere (initial ^{pressure: 0.98MPa (10Kg / cm 2 G} )) to 380 ° C., and held 60 min. Thereafter, the reaction product was taken out from the autoclave and heat-treated at 430 ° C. for 30 minutes under a nitrogen gas flow to remove light components to obtain modified coal.
A blended coal was prepared by adding a base blended coal of caking coal prepared by mixing four modified (A to D coal) coals (coking coal for coke) shown in Table 1 to 10% by mass of this modified coal. . And this coal mix was dry-distilled in a 1100 degreeC coke oven for 18 to 20 hours, and coke was obtained. The drum strength (DI ³⁰ ₁₅ ) of the prepared coke was measured according to JIS K2151. The results are shown in Table 2.

(Comparative Example 6)
The same lignite as in Example 1 was freeze-dried, placed in a SUS rotary kiln furnace with an inner diameter of 600 mm, heated from room temperature to 600 ° C. at a rate of 5 ° C./min under nitrogen gas flow, and then at 600 ° C. for 60 minutes. Hold and fired. Table 2 shows the properties of the obtained fired product.
Next, 5 kg of the fired product and 20 kg of pitch were put into an induction-stirring autoclave having an internal volume of 50 liters, and maintained at 280 ° C. for 60 minutes in a nitrogen atmosphere (initial pressure: 0.98 MPa (10 Kg / cm ² G)). Thereafter, the reaction product was taken out from the autoclave and heat-treated at 430 ° C. for 30 minutes under a nitrogen gas flow to remove light components to obtain modified coal.
A blended coal was prepared by adding a base blended coal of caking coal prepared by mixing four modified (A to D coal) coals (coking coal for coke) shown in Table 1 to 10% by mass of this modified coal. . And this coal mix was dry-distilled in a 1100 degreeC coke oven for 18 to 20 hours, and coke was obtained. The drum strength (DI ³⁰ ₁₅ ) of the produced coke was measured according to JIS K2151. The results are shown in Table 2.

(Comparative Example 7)
The same lignite as in Example 1 was freeze-dried, placed in a SUS rotary kiln furnace with an inner diameter of 600 mm, heated from room temperature to 600 ° C. at a rate of 5 ° C./min under nitrogen gas flow, and then at 600 ° C. for 60 minutes. Hold and fired. Table 2 shows the properties of the obtained fired product.
Next, 5 kg of the fired product and 20 kg of pitch were put into an induction stirring autoclave having an internal volume of 50 liters, and kept at 600 ° C. for 60 minutes in a nitrogen atmosphere (initial pressure: 0.98 MPa (10 Kg / cm ² G)). Thereafter, the reaction product was taken out from the autoclave and heat-treated at 430 ° C. for 30 minutes under a nitrogen gas flow to remove light components to obtain modified coal.
A blended coal was prepared by adding a base blended coal of caking coal prepared by mixing four modified (A to D coal) coals (coking coal for coke) shown in Table 1 to 10% by mass of this modified coal. . And this coal mix was dry-distilled in a 1100 degreeC coke oven for 18 to 20 hours, and coke was obtained. The drum strength (DI ³⁰ ₁₅ ) of the produced coke was measured according to JIS K2151. The results are shown in Table 2.

From the results of Table 2, in all of Examples 1 to 4, the oxygen content of the brown coal after the heat treatment was 15% by mass or less, and the generation of water during the reforming treatment could be suppressed. Moreover, the specific surface area of the lignite after the heat treatment is in the range of 310 to 1020 m ² / g, and the large specific surface area allows the decomposition products of heavy oils to adhere to produce high strength coke. It was. In particular, in Examples 1 and 4, adhesion of decomposition products was promoted by supporting Fe on lignite, and high coke strength could be obtained.
On the other hand, in Comparative Examples 1 and 2, since heat treatment and reforming treatment were not performed, a large amount of water remained in the lignite, and a large amount of water was generated together with coke. Moreover, in Comparative Examples 3 and 4, since the oxygen content of the brown coal after the heat treatment is high (> 15% by mass) and the specific surface area is small, the decomposition products of heavy oils can be sufficiently attached. It was not possible, and the strength of the coke was lowered. In Comparative Examples 5 to 7, high coke strength could not be obtained.

  The present invention can be used in fields such as thermal power generation, petroleum refining, and chemical industry in addition to use as raw material coal for steel.

Claims (7)

In a method for producing modified coal by treating low-grade coal with heavy oils, a deoxidation step of heat-treating low-grade coal containing a large amount of oxygen atoms to reduce the oxygen content to 15% by mass or less; ,
The low-grade coal after deoxidation is heated at a temperature of 300 to 500 ° C. together with heavy oils, and a reforming step for attaching the decomposition products of heavy oils to the surface of the low-grade coals;
A method for producing modified coal, characterized in that   In the deoxidation step, the low-grade coal is dried, then heated in an inert gas atmosphere or a reducing gas atmosphere in a temperature range of more than 400 ° C. and 800 ° C. or less, and further in an oxidizing gas atmosphere, 800 to 1200 ° C. The method for producing reformed coal according to claim 1, wherein the method undergoes a step of heating in the temperature range.   The deoxidation step is a step of heating a low-grade coal in a temperature range of 300 to 1200 ° C in an inert atmosphere or a reducing atmosphere after freeze-drying or supercritical drying. 2. A method for producing reformed coal according to 1.   The method for producing modified coal according to any one of claims 1 to 3, wherein the low-grade coal after deoxidation is a porous body.   The method for producing reformed coal according to any one of claims 1 to 4, wherein the reforming step is performed in a hydrogen-containing atmosphere.   The method for producing modified coal according to any one of claims 1 to 5, wherein a metal and / or a metal compound is supported on the low-grade coal after deoxidation.   Coke characterized by being charged into a coke oven with the blended coal containing the modified coal obtained by the method according to any one of claims 1 to 6 and heating and dry distillation at a temperature of 1000 to 1200 ° C. Manufacturing method.