Method for manufacturing a binder for coke production and method for manufacturing coke

Abstract

The present invention provides a method for producing a coke binder with softening and melting properties using biomass, and a method for producing coke using the same binder. [Solution] A method for producing a binder for coke production, characterized by heating a mixture of biomass, alkali, and alcohol at 185°C to 225°C for 10 minutes or more, cooling, separating the cooled reaction product into solid and liquid under acidic conditions, and using the separated solid as a binder.

Description

TECHNICAL FIELD

[0001] The present invention relates to a method for producing a binder for coke production and a method for producing coke using the same. BACKGROUND ART

[0002] Conventionally, development of production technologies for blast furnace coke using low-grade coal has been carried out. For example, coke is produced by blending a binder with low-grade coal. Patent Document 1 describes a method of modifying a binder by adding and mixing a metal salt of a fatty acid or a metal salt source of a fatty acid to coal having no caking property, followed by heat treatment. It is described that when this binder is added to coal at 30% and the mixture is calcined, the strength is improved compared to the case where the binder is added at 10%. PRIOR ART DOCUMENTS PATENT DOCUMENTS

[0003] PATENT DOCUMENT 1 Japanese Patent Laid-Open No. 56-20085 SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] Meanwhile, utilization of biomass, which is a carbon-neutral resource, is also being studied in coke production. However, biomass does not exhibit softening and melting properties during the carbonization process. Therefore, when biomass is added as a raw material (including a binder) for producing blast furnace coke, the strength of coke is significantly reduced, so that biomass cannot be used as a binder.

[0005] Accordingly, the present application aims to provide a method for producing a binder for coke production that has softening and melting properties using biomass, and a method for producing coke using the binder. MEANS FOR SOLVING THE PROBLEMS

[0006] This application was made to solve the above-mentioned problems, and its gist is as follows.

[0007] (1) A method for producing a binder for coke production, characterized by heating a mixture of biomass, alkali, and alcohol at 185°C to 225°C for 10 minutes or more, cooling, separating the cooled reaction product into solid and liquid under acidic conditions, and using the separated solid as a binder.

[0008] (2) A method for producing a binder for coke production, characterized by heating a mixture of biomass, alkali, and alcohol at 155°C to 240°C for 10 minutes or more, cooling it, adding water to the cooled reaction product to separate it into solid and liquid, separating the liquid obtained from the separation into solid and liquid under acidic conditions, and using the solid obtained from the separation as a binder.

[0009] (3) A method for producing a binder for coke production according to (1) or (2) above, characterized in that the alkali is at least one of KOH, NaOH, and Ca(OH)2.

[0010] (4) The method for producing a binder for coke production according to (1) or (2) above, characterized in that the alcohol is at least one of ethanol, butanol, and isopropyl alcohol.

[0011] (5) A method for producing coke, characterized by adding the binder produced by the method of (1) or (2) above to coal having a maximum fluidity of 0 ddpm or more and 10 ddpm or less, compressing and molding to produce a molded product, and carbonizing the molded product to produce coke. [Effects of the Invention]

[0012] According to this application, it is possible to provide a method for producing a coke binder with softening and melting properties using biomass, and a method for producing coke using the same binder. [Brief explanation of the drawing]

[0013] [Figure 1] This is a flowchart of the manufacturing method for the binder of the embodiment. [Figure 2] This is a flowchart of a method for manufacturing a binder according to another embodiment. [Figure 3] This figure shows the relationship between the indirect tensile strength and heat treatment temperature of the coke in Example 1. [Figure 4] This figure shows the relationship between the indirect tensile strength and heat treatment temperature of the coke in Example 2. [Modes for carrying out the invention]

[0014] (First embodiment) <Method for manufacturing binders> This embodiment will be described with reference to the drawings. Figure 1 is a flowchart of the method for producing a binder for blast furnace coke production using biomass according to this embodiment. The method for producing the binder according to this embodiment involves heating biomass in an alkali-alcohol solution within a predetermined temperature range to decompose the components in the biomass (cellulose, hemicellulose, lignin) and reduce their molecular weight, thereby obtaining a binder suitable for coke production. The binder obtained by this method is a binder that softens and melts during the carbonization process when mixed with coal to produce coke. In the following description of the embodiments, the mixing ratios and addition rates are given as mass fractions (%) unless otherwise specified.

[0015] First, the biomass used in the method for producing the binder of this embodiment will be described. Various types of biomass can be used and are not particularly limited. Examples of biomass that can be used include woody biomass (pine, cedar, beech, cypress, etc.), herbaceous biomass (grasses, legumes, etc.), agricultural residues (rice straw, rice husks, almond shells, walnut shells, etc.), oil extraction residues (palm kernel shells (PKS), empty palm fruit clusters (EFB), etc.), waste biomass (sewage sludge, municipal solid waste, etc.), and food biomass (coffee grounds, etc.). Biomass other than those exemplified above can also be used. The form and state of the biomass are not particularly limited. For example, in the case of woody biomass, sawdust or chips can be used. Among biomass, it is preferable to use woody biomass that contains a larger amount of lignin-like substances, which are the source of low molecular weight components that exhibit softening and melting properties during the carbonization process to coke.

[0016] The biomass is preferably composed of particles with a particle size of less than 1000 μm. Particle size adjustment can be performed, for example, using a sieve, and the material below a 1000 μm sieve can be used in the production of the binder. Alternatively, the biomass can be crushed to adjust the particle size.

[0017] The steps for manufacturing the binder are described below. First, an alkali and an alcohol are added to the biomass (S1). A strong alkali can be used as the alkali. Specifically, at least one of KOH, NaOH, or Ca(OH)2 can be used. A lower alcohol with 5 or fewer carbon atoms can be used as the alcohol. Specifically, at least one of ethanol, butanol (including isomers), or isopropyl alcohol can be used. These can be mixed using an appropriate reactor. Note that multiple types of alkali and alcohol can be used in combination.

[0018] The mass ratio of the biomass to be mixed and the alkali can be set such that the alkali is in a ratio of 0.5 to 3 relative to 1 of the biomass. The ratio of biomass to alcohol can be set to an amount that allows the entire biomass to be immersed in the alcohol in the reactor.

[0019] Next, the mixture of biomass, alkali and alcohol is subjected to a heat treatment (S2). That is, the biomass is heat-treated in an alkali-alcohol solution. The inside of the reactor is heated at a predetermined temperature rise rate to a predetermined heat treatment temperature and held there. The heat treatment can be performed after the gas in the reactor is replaced with nitrogen. The temperature rise rate of the reactor is not particularly limited, and can be 3°C / min or more and 30°C / min or less. In addition, the heat treatment temperature can be 185°C or more and 225°C or less. This is because when the heat treatment temperature is within the aforementioned range, coke having excellent strength can be obtained when coke is produced using the produced binder. The heat treatment time (holding time) at the heat treatment temperature is preferably 10 minutes or more. The upper limit of the heat treatment time is not particularly limited, and can be, for example, 60 minutes or less.

[0020] Next, the reaction product obtained by the heat treatment is cooled (S3). The cooling method is not limited, and can be performed, for example, by immersing the reactor in a water bath. In this cooling step, it is sufficient to cool to room temperature.

[0021] Next, an acid is added to the reaction product (S4). By making the solution acidic through the addition of the acid, components with high softening and melting properties dissolved in the solution are precipitated on the solid side. Examples of the acid include inorganic acids such as hydrochloric acid and sulfuric acid, and organic acids such as acetic acid and formic acid. The concentration of each of hydrochloric acid and sulfuric acid can be 0.2 mol / L or more and 5.0 mol / L or less. The concentration of acetic acid can be 9.0 mol / L or more and 17.5 mol / L or less, and the concentration of formic acid can be 13.0 mol / L or more and 26.5 mol / L or less. The solution can also be made acidic by blowing CO₂ gas into the solution.

[0022] Next, the reaction product after adding the acid is subjected to solid-liquid separation (S5). The solid and liquid can be separated by filtration, and the solid is recovered and used. The filtration method is not particularly limited as long as solid-liquid separation can be performed, but it can be done by natural filtration using filter paper.

[0023] Next, the solid obtained by solid-liquid separation is vacuum-dried (S6). Vacuum drying removes moisture from the solid. The material obtained by vacuum drying is the binder of this embodiment. Hereinafter, the binder obtained by the method of this embodiment will also be referred to as "binder 1".

[0024] <Methods for producing coke> Next, the method for producing coke according to this embodiment will be described. Coke can be produced by mixing coal and the manufactured binder 1 in a predetermined ratio, compressing and molding the mixture, and then carbonizing the molded product.

[0025] The type of coal used is not particularly limited, but coal with little or no softening and melting properties can be used. Such coal, when carbonized to produce coke, lacks sufficient softening and melting properties and therefore has insufficient strength. Combining it with the binder of this embodiment, which possesses softening and melting properties, allows for a greater enjoyment of the binder's softening and melting effect. As an example of coal with little or no softening and melting properties, coal with a maximum fluidity (MF) of 0 ddpm or more and 10 ddpm or less can be used. This MF is the Gieseler maximum fluidity measured using the fluidity test method (Giesler plastometer method) in accordance with JIS M 8801. Examples of such coal include non-caking coal, slightly caking coal, semi-anthracite, and anthracite. It is preferable to crush the coal to less than 500 μm before use. Of course, coke can also be produced by blending the binder of this embodiment with coal that possesses softening and melting properties.

[0026] The specified mixing ratio of the binder can be between 3% and 50% when the total mass of the mixture with coal is considered to be 100%. This is because within this range, coke with sufficient indirect tensile strength for use in blast furnaces can be obtained. If the ratio is less than 3% (lower limit) or more than 50% (upper limit), sufficient strength of the coke may not be obtained.

[0027] Compression molding is not limited to any particular method, as long as it can be molded into a shape and dimensions suitable for blast furnace coke. For example, it can be molded into the desired shape and size (dimensions, volume) using a uniaxial compression molding machine, briquetting machine, or pelletizer. The shape can be, for example, cylindrical, masec type, or pillow type. The size can be, for example, between 0.5 cc and 100 cc. By compression molding, the density of the molded product is 800 kg / m³. 3 More than 1300kg / m 3 The following range is possible.

[0028] The carbonization of the molded material can be carried out in the same manner as the conventional carbonization of coal to coke. That is, carbonization is performed by blocking out air and, if necessary, maintaining an inert gas atmosphere at a carbonization temperature of 900°C to 1200°C for 10 to 120 minutes. The heating rate to the carbonization temperature can be 0.5°C / min to 20°C / min. The coke obtained by carbonizing the molded material is the coke of this embodiment. The above describes the method for producing coke of this embodiment.

[0029] The method for producing a binder for coke production according to this embodiment makes it possible to produce a binder that exhibits softening and melting properties from biomass that does not show softening and melting properties during the carbonization process to coke. By adding the prepared binder to coal that has little or no softening and melting properties according to the coke production method of this embodiment, it is possible to produce coke with sufficient strength for use in blast furnaces.

[0030] The reason why a binder produced by heating biomass in an alkali-alcohol solution exhibits softening and melting properties during the carbonization process to coke is thought to be as follows: Biomass has more oxygen-containing functional groups than coal, which exhibits softening and melting properties. Therefore, even if low-molecular-weight components (components that soften and melt) are generated by the thermal decomposition of biomass during the carbonization process, these generated low-molecular-weight components polymerize again via ether bonds formed by oxygen-containing functional groups, causing the softening and melting properties to be lost. Consequently, even if biomass is used directly in a mixture with coal, the biomass will not exhibit softening and melting properties during the carbonization process, and the resulting coke will lack sufficient strength. In contrast, by heating biomass in an alkali-alcohol solution at a temperature between 185°C and 225°C, the ether bonds can be cleaved, generating low-molecular-weight components. Since these low-molecular-weight components have softening and melting properties during the carbonization process, the binder of this embodiment can be used to produce blast furnace coke with sufficient strength.

[0031] Furthermore, if the heat treatment temperature is below 185°C, the cleavage of the ether bonds is insufficient, and the softening and melting properties are reduced. Also, if the heat treatment temperature exceeds 225°C, the low-molecular-weight components undergo polymerization reactions, which reduces the softening and melting properties during the carbonization process.

[0032] (Second embodiment) Another embodiment of the method for manufacturing the binder will be described. In this embodiment, between the cooling step S3 and the acid addition step S4 of the method for manufacturing the binder in the first embodiment, there is a step of adding water (S24) and a solid-liquid separation step (S25). In addition to these steps, the range of the heat treatment temperature in the heat treatment of biomass in the alkali-alcohol solution (S22) is different. The flow of the method for manufacturing the binder in this embodiment will be described below. The same parts as in the first embodiment will be omitted from the explanation.

[0033] First, alkali and alcohol are added to the biomass (S21), and then it is heat-treated (S22). In this embodiment, the heat treatment temperature can be 155°C or higher and 240°C or lower. In this embodiment, the concentration of the softening and melting component in the reaction product is increased by an additional step of adding water and separating the solid and liquid. Therefore, in the heat treatment step, the heat treatment can be performed over a wider temperature range than in the first embodiment. Also, the heat treatment temperature in this embodiment may be 200°C or higher and 240°C or lower. This can further improve the strength of the coke produced using the binder. Furthermore, the heat treatment temperature may be 210°C or higher and 220°C or lower. This can further improve the strength of the coke. The heating rate and heat treatment time may be the same as in the first embodiment.

[0034] Next, after cooling by a cooling process (S23), water is added to the reaction product (S24). The amount of water added should be the amount necessary to recover the reaction product in the reactor. After adding water, the reaction product separates into liquid and solid by standing.

[0035] Next, the reaction product to which water has been added is subjected to solid-liquid separation (S25). Similar to the solid-liquid separation process in step S5 described above, it can be separated into solid and liquid by filtration. The filtration method is not particularly limited as long as it can separate the solid and liquid, but it can be carried out by natural filtration using filter paper.

[0036] Next, acid is added to the liquid (filtrate) obtained by solid-liquid separation (S26). Then, the reaction product to which the acid has been added is subjected to solid-liquid separation in the same manner as in the first embodiment (S27), and the resulting solid is vacuum-dried (S28). The binder of this embodiment is obtained through the above steps. Hereinafter, the binder obtained by the method of this embodiment will also be referred to as "binder 2". Hereinafter, instead of adding acid, the liquid (filtrate) can be made acidic by blowing CO2 gas into it, which can then be used for solid-liquid separation.

[0037] The binder 2 produced by the manufacturing method of this embodiment has a wider range of heat treatment temperatures over which the coke strength-improving effect manifests compared to the binder 1 of the first embodiment. Furthermore, the degree of strength improvement (effect range) is also greater. This is understood to be because, as described above, the method of this embodiment separates and removes high-molecular-weight components that do not dissolve in water or alkali-alcohol solutions by adding water and performing solid-liquid separation (S24, S25), thereby increasing the concentration of low-molecular-weight components with softening and melting properties contained in the resulting binder.

[0038] Using the binder 2 of this embodiment, coke can be manufactured in the same manner as when using the binder 1 of the first embodiment. As described above, the method of this embodiment makes it possible to manufacture coke with superior strength. [Examples]

[0039] (Example 1) Samples of binders were prepared at various heat treatment temperatures using the method of the first embodiment. Coke was also produced using each of the binder samples.

[0040] <Manufacturing of adhesives> As biomass, pine sawdust with a particle size of less than 500 μm (below 500 μm sieve), adjusted by sieving, was used. 5 g of sawdust, 5 g of NaOH, and 50 mL of ethanol were placed in the reactor. After replacing the gas in the reactor with nitrogen, the reactor was heated at approximately 10 °C / min to the respective heat treatment temperatures. The heat treatment temperatures were 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C, 220 °C, and 240 °C, and binders were prepared at each temperature. Of these, the binders finally obtained by heat treatment at temperatures from 190 °C to 220 °C correspond to binder 1 of the embodiment. After being held at the heat treatment temperature for 30 minutes, it was cooled in a water bath. 200 mL of a 2 mol / L aqueous HCl solution was added to the reaction product (a mixture of solid and liquid) in the reactor, and then the solid and liquid were separated and recovered by natural filtration using filter paper. The recovered solid was vacuum-dried to remove moisture and obtain the binder for each sample.

[0041] <Coke production> Non-caking coal (MF: 0ddpm, volatile matter VM: 50%) that does not soften or melt was crushed to less than 500 μm, and 30% (internal percentage) of the prepared binder was added and mixed (i.e., 70% coal, 30% binder). The mixture was compressed and molded using a uniscrew compression molding machine under conditions of 30 MPa to obtain a cylindrical molded product with a diameter of 15 mm and a thickness of 10 mm. The molded product was heated in an inert gas atmosphere at 5°C / min to 900°C, held for 30 minutes, and then carbonized to produce coke.

[0042] <Strength Test> The strength of the prepared coke was evaluated using the crushing strength test method, and the indirect tensile strength was calculated using the following formula (1). This method is the evaluation method described in "Journal of the Fuel Association," Vol. 54, No. 584 (1975), pp. 983-993. f = 2·P / (π·d·l) (1) Here, f is the indirect tensile strength [MPa], P is the crushing strength [N], d is the sample diameter [mm], and l is the thickness [mm].

[0043] Figure 3 shows the indirect tensile strength of each coke sample. The vertical axis represents the indirect tensile strength [MPa], and the horizontal axis represents the heat treatment temperature [°C] in the alkali-alcohol solution used to prepare the binder. For comparison, Figure 3 shows the indirect tensile strengths of coke prepared in the same way with 20% asphalt pitch (ASP) added as a binder instead of the binder made from biomass (ASP 20% added coke), coke prepared in the same way with 30% asphalt pitch added (ASP 30% added coke), and coke prepared using only non-coking coal without any binder added (additive-free coke) as dashed lines. The indirect tensile strength of ASP 20% added coke is approximately 2.5 MPa, and that of ASP 30% added coke is approximately 7.6 MPa. Note that an indirect tensile strength of 2.5 MPa or higher can be evaluated as having sufficient strength for use as blast furnace coke.

[0044] As shown in Figure 3, in the case of coke produced by adding a binder prepared under conditions where the heat treatment temperature in the biomass alkali-alcohol solution was 180°C or lower, the indirect tensile strength of the coke was approximately 1 MPa or less. In contrast, when the heat treatment temperature was 190°C, the strength increased sharply, reaching approximately 3.5 MPa. Furthermore, when the heat treatment temperature was between 190°C and 220°C, the indirect tensile strength of the coke ranged from approximately 2.8 MPa to approximately 4.0 MPa, achieving an indirect tensile strength equivalent to that of ordinary blast furnace coke. When the heat treatment temperature exceeded 220°C, the indirect tensile strength of the coke decreased significantly, falling to approximately 1.0 MPa at 240°C.

[0045] (Example 2) Samples of binders were prepared at various heat treatment temperatures using the method of the second embodiment. Coke was also produced using each of the binder samples.

[0046] <Manufacturing of adhesives> Similar to Example 1, pine sawdust (particle size less than 500 μm), a biomass, was used, and the same amount of sawdust, NaOH, and ethanol as in Example 1 were added to the reactor and heat-treated. The heat-treatment temperatures were similarly set to 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, and 240°C, and binders were prepared for each. Of these, the binders finally obtained by heat-treating at temperatures from 160°C to 240°C correspond to binder 2 of the embodiment. After heat treatment and cooling, 100 mL of water was added to the reaction product in the reactor, and the solid and liquid were separated by natural filtration. To the separated liquid, 200 mL of a 2 mol / L aqueous HCl solution was added as in Example 1, and solid-liquid separation was performed by filtration. The recovered solid was vacuum-dried to obtain the binder for each sample.

[0047] <Coke production> Coke was produced using the same non-caking coal and the binder for each sample, in the same manner as in Example 1.

[0048] <Strength Test> The indirect tensile strength of coke was calculated in the same manner as in Example 1. The indirect tensile strength of each coke is shown in Figure 4. As shown in Figure 4, in the case of coke produced by adding a binder prepared under conditions where the heat treatment temperature in the biomass alkali-alcohol solution was 150°C or lower, the indirect tensile strength of the coke was less than 1.0 MPa. In contrast, when the heat treatment temperature was 160°C, the strength improved significantly. In the range of heat treatment temperatures from 160°C to 200°C, the indirect tensile strength of the coke improved with increasing temperature, and increased sharply from 210°C to 220°C, reaching approximately 7.5 MPa, resulting in coke with an indirect tensile strength comparable to ASP. When the heat treatment temperature was 240°C, the indirect tensile strength of the coke decreased slightly to approximately 5.5 MPa, but sufficient strength was still obtained.

[0049] As shown in Figure 4, the binder corresponding to binder 2 in Example 2 had a wider range of heat treatment temperatures over which the coke strength improvement effect was observed compared to the binder corresponding to binder 1 in Example 1 (binder 1 was 190°C to 220°C, while binder 2 was 160°C to 240°C). Furthermore, since binder 2 produced coke with higher strength, it was confirmed that the strength improvement effect was also greater. The reason for this is understood to be that, as mentioned above, in the method of the second embodiment, the addition of water and solid-liquid separation treatment separated high-molecular-weight components that do not dissolve in water or alkali-alcohol solutions, thereby increasing the concentration of low-molecular-weight components with softening and melting properties in the binder.

Claims

1. A method for producing a binder for coke production, characterized by heating a mixture of biomass, alkali, and alcohol at 185°C to 225°C for 10 minutes or more, cooling the mixture, separating the cooled reaction product into solid and liquid under acidic conditions, and using the separated solid as a binder.

2. A method for producing a binder for coke production, characterized by heating a mixture of biomass, alkali, and alcohol at 155°C to 240°C for 10 minutes or more, cooling it, adding water to the cooled reaction product to separate it into solid and liquid, separating the resulting liquid into solid and liquid under acidic conditions, and using the separated solid as a binder.

3. The alkalis mentioned above are KOH, NaOH, and Ca(OH) ２ A method for producing a binder for coke production according to claim 1 or 2, characterized in that it is at least one of the following.

4. The method for producing a binder for coke production according to claim 1 or 2, characterized in that the alcohol is at least one of ethanol, butanol, and isopropyl alcohol.

5. A method for producing coke, characterized by adding the binder produced by the method of claim 1 or 2 to coal having a maximum fluidity of 0 ddpm or more and 10 ddpm or less, producing a molded product by compression molding, and producing coke by carbonization of the molded product.

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