Method for suppressing natural heat release of solid carbon resource and method for storing solid carbon resource using same

Abstract

The method for suppressing natural heat release of a solid carbon resource includes a step of adding a petroleum-based additive to the solid carbon resource as a natural heat release suppressing agent.

Description

Technical Field

[0001] The present invention relates to a method for suppressing natural heat generation of solid carbon resources and a method for storing solid carbon resources using the same.

[0002] This application claims priority based on Japanese Patent Application No. 2023-2772 filed in Japan on January 12, 2023, the contents of which are incorporated herein by reference. Background Art

[0003] Solid carbon resources such as coal and biochar, which is expected to be used more widely in the future, are sometimes stored in large quantities in stockpiles, etc. Since solid carbon resources naturally release heat, their temperature must be carefully managed.

[0004] Several technologies have been proposed to suppress the spontaneous exotherm of such solid carbon resources. For example, Patent Document 1 discloses a method in which a heat-increase / spontaneous combustion suppressant containing at least one substance selected from a radical scavenger and an oxygen scavenger is used to reduce the amount of free radicals generated by the reaction of carbonaceous powder with oxygen, thereby suppressing the heat-increase / spontaneous exotherm. Patent Document 1 also discloses that a nonionic surfactant may also be included.

[0005] Patent Document 2 discloses a method for producing upgraded coal, wherein spontaneous combustion is suppressed by drying coal in an atmosphere containing a radical scavenger containing an organic compound having a hydroxyl group, such as alcohol or phenol.

[0006] Furthermore, Patent Document 3 discloses a stabilization method in which coal is heated at a temperature of 100 to 350° C. until its moisture content is substantially 0% by weight and then oxidized to simultaneously achieve dehydration and prevent spontaneous combustion.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2001-164254

[0010] Patent Document 2: Japanese Patent Application Laid-Open No. 2011-201947

[0011] Patent Document 3: Japanese Patent Application Laid-Open No. 59-074189 Summary of the Invention

[0012] Problems to be solved by the invention

[0013] However, the method described in Patent Document 1 requires the use of large quantities of specific compounds, which presents cost challenges. For example, adding a considerable amount of a nonionic surfactant as an exothermic suppressant to carbonaceous powders, which are used extensively in industry, is likely to further increase production costs. Furthermore, the method described in Patent Document 2 also makes the addition of a considerable amount of an organic compound having a hydroxyl group costly.

[0014] In Patent Document 3, heat generation is suppressed by intentionally performing oxidation treatment after dehydration of coal, but the effect of oxidation treatment when dehydration is not necessary is unclear.

[0015] As described above, in the conventional methods, further improvements are required in terms of cost and simplicity of the process.

[0016] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an inexpensive and simple method for suppressing the natural heat generation of solid carbon resources and a solid carbon resource storage method using the same.

[0017] Means for solving problems

[0018] (1) A method for suppressing the natural heat release of a solid carbon resource, comprising the step of adding a petroleum-based additive to the solid carbon resource as a natural heat release suppressor.

[0019] (2) The method for suppressing spontaneous heat generation of a solid carbon resource according to (1), wherein 1% by mass or more of the petroleum-based additive is added to the solid carbon resource.

[0020] (3) The method for suppressing the natural heat release of solid carbon resources according to (1) or (2), further comprising the step of heating the solid carbon resources to which the above-mentioned petroleum-based additives are added at a temperature of 20° C. or higher for more than 1 hour in an inert gas atmosphere.

[0021] (4) A method for storing a solid carbon resource, comprising storing the solid carbon resource treated by the method according to any one of (1) to (3).

[0022] Effects of the Invention

[0023] According to the present invention, by including the step of adding a petroleum-based additive to a solid carbon resource, the natural heat release of the solid carbon resource can be reduced simply and at low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a graph showing the corrected temperature rise curves of Test Nos. 1 to 4 (Comparative Example 1, Inventive Examples 1 to 3).

[0025] Figure 2This is a graph comparing the values ​​of T200 delay time calculated from the corrected temperature rise curves of Test Nos. 1 to 4 (Comparative Example 1, Inventive Examples 1 to 3).

[0026] Figure 3 This is a graph showing the corrected temperature rise curves of Test No. 4 (Invention Example 3) of Example 1 and Test Nos. 5 to 8 (Invention Examples 4 to 7) of Example 2.

[0027] Figure 4 This is a graph comparing the values ​​of T200 delay time calculated from the corrected temperature rise curves in Test No. 4 of Example 1 (Invention Example 3) and Test Nos. 5 to 7 of Example 2 (Invention Examples 4 to 6). DETAILED DESCRIPTION

[0028] The present inventors conducted intensive research to solve the above-mentioned problems, focused on petroleum-based additives, and conducted repeated experiments, resulting in the present invention.

[0029] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0030] It should be noted that, in this specification, solid carbon resources are not particularly limited as long as they are solid materials with carbon as the main component, for example, raw materials for coke production, carbon materials used as fuel or heating agents in power generation, converters, etc. Examples of carbon materials include fossil resources (coal such as anthracite, bituminous coal, sub-bituminous coal, lignite, and peat), organic resources of biological origin (biomass itself, biochar produced by heat-treating biomass as a material (carbonized or semi-carbonized biomass such as charcoal and black pellets)), etc. In addition, in this specification, petroleum-based heavy oil refers to crude oil with a heavy component obtained by refining petroleum, high viscosity and high specific gravity, petroleum-based tar refers to a black to brown oily substance with a sticky gas generated by thermal decomposition of petroleum or petroleum-derived substances, and petroleum-based asphalt refers to the residual component after refining petroleum, gasoline, etc. from crude oil, or the residue obtained by vacuum distillation of petroleum. In addition, petroleum-based heavy oil is liquid at room temperature (20° C.), and petroleum-based tar and petroleum-based asphalt are solid at room temperature (20° C.).

[0031] The petroleum additive is composed of at least one of petroleum heavy oil, petroleum tar, and petroleum asphalt. The petroleum additive is an additive derived from petroleum and is a petroleum additive.

[0032] The petroleum additive is preferably composed of at least one of petroleum tar and petroleum asphalt, more preferably composed of at least one of petroleum heavy oil and petroleum asphalt, and even more preferably composed of petroleum asphalt.

[0033] The present invention relates to a method for suppressing the natural exotherm of solid carbon resources, which includes a process of adding a petroleum-based additive to the solid carbon resources, and a method for storing the solid carbon resources treated by the method. Petroleum-based additives have been used industrially as a binder for coal when coal is used as a raw material for producing coke. Specifically, in order to supplement the adhesiveness of coal with low expansion (non-caking coal, etc.), it is used as a binder that exhibits adhesiveness at high temperatures (350°C to 550°C). However, the inventors have newly discovered that petroleum-based additives have the effect of suppressing the natural exotherm of solid carbon resources by being added to and mixed with solid carbon resources. That is, in the present invention, petroleum-based additives are used as additives for suppressing natural exotherm (natural exotherm inhibitors).

[0034] The coke production process in the iron and steel industry's ironmaking process, for example, sequentially includes a loading process, a coal storage process (such as a stockyard), a coal blending process, a crushing process, a molding process, and a coke oven loading process. A petroleum-based additive serving as a binder is added to the coal blended with a predetermined amount of raw coke in the coal blending process after the coal blending process (see Japanese Patent Application Laid-Open Nos. 2014-70125 and 2008-120973, etc.). In contrast, in the iron and steel industry's ironmaking process, when a petroleum-based additive is used as a natural heat suppressant, as in the present invention, it is preferably implemented at a certain stage between the loading process and the coal blending process (including the loading and transporting processes between the aforementioned processes from the loading process to the coal blending process). It is more preferred to implement the addition of petroleum-based additives in one or both of the following: after the loading process and before the coal storage process (for example, the stage before coal (raw coal) is unloaded from the ship and moved to a coal storage yard such as a material yard) and after the coal storage process and before the coal blending process (for example, the stage before coal is transported from the coal storage yard to the coal blending yard). It should be noted that, when using petroleum-based additives as natural exothermic inhibitors, the effect can be enjoyed regardless of the stage before the coke oven loading process at which the petroleum-based additives are added, but by adding them on the upstream side of the process flow, the possibility of natural fire on the downstream side can be suppressed. Except for the ironmaking process in the steel industry (for example, coal-fired power generation process), when using petroleum-based additives as natural exothermic inhibitors of coal, they are added at the stage before the process of using coal as fuel. For example, after the loading process and before the coal storage process, when storing coal in the material yard, when transporting coal from the material yard to the coal storage tank, when storing coal in the coal storage tank, or at least one stage of the coal blending process, it is preferred to add them on the upstream side. More specifically, the natural heat generation inhibitor may be mixed with the coal before storage in the material yard or coal storage seam and then stored, or the natural heat generation inhibitor may be added to the coal during storage (in the storage state).

[0035] The natural exothermicity of solid carbon resources is due to the diverse and highly reactive free radicals that are abundant in solid carbon resources, which drive oxidation reactions. It is believed that because petroleum additives (at least one of petroleum-based heavy oil, petroleum-based asphalt, and petroleum-based tar) contain a large number of structures with hydrogen-donating properties, such as naphthalene rings, this hydrogen-donating property causes certain chemical interactions (trapping free radicals) with solid carbon resources, which can promote oxidation inhibition reactions of solid carbon resources and exhibit a natural exothermic inhibition effect of solid carbon resources. It is known that aromatic compounds with naphthalene rings that have hydrogen-donating properties can promote the softening and melting properties of coal, but their effect on suppressing the natural exothermicity of solid carbon resources is unknown.

[0036] Hereinafter, an example of an embodiment of the present invention will be described in detail.

[0037] <First embodiment>

[0038] In the present embodiment, the heat release suppression treatment of the solid carbon resource is performed by adding a petroleum additive. Here, it is preferred that the solid carbon resource be pre-treated before the addition treatment of the petroleum additive. In addition, the petroleum additive is preferably pre-treated before being added to the solid carbon resource. Furthermore, it is preferred that a mixing process and a storage process be performed after the addition treatment of the petroleum additive. That is, in the first embodiment, it is preferred that the pre-treatment process of the solid carbon resource and the pre-treatment process of the petroleum additive be performed first, followed by the petroleum additive addition process, followed by the mixing process, and then the storage process. From the viewpoint of suppressing the natural heat release of the solid carbon resource, it is sufficient to at least perform the petroleum additive addition process, and when storage is also performed, it is preferred that the storage process be performed next. However, in order to maximize the effect of the present embodiment, it is preferred to perform each of the above processes.

[0039] (Pre-treatment process of solid carbon resources, pre-treatment process of petroleum additives)

[0040] The pre-treatment of solid carbon resources is, for example, a particle size adjustment process of the solid carbon resources as a raw material. The pre-treatment of petroleum additives is, for example, a particle size adjustment process of the petroleum additives as a raw material. The pre-treatment of petroleum additives is performed as needed. For example, it can be performed when the petroleum additive is solid. The particle size of solid carbon resources and petroleum additives can be adjusted by, for example, crushing, classification, etc. Crushing can be performed using various crushers such as ball mills, bead mills, mortars, hammer mills, etc. In addition, classification can be performed using, for example, dry classifiers such as grading screens, gravity classifiers, inertial classifiers, centrifugal classifiers, etc.

[0041] In this process, in order to carry out the oxidation inhibition reaction in a short time, it is preferred that the particle size of the petroleum additive is set to be relatively small to promote the oxidation inhibition reaction. Specifically, the petroleum additive is preferably less than 5mm in particle size, more preferably less than 2mm in particle size. In addition, when mixed with solid carbon resources, if the petroleum additive is too fine, it cannot be mixed well, so the petroleum additive is preferably more than 1mm in particle size. It should be noted that the particle size is specified using a sieve. The particles under the sieve of the sieve with a mesh size of Xmm are defined as particles less than Xmm, and the particles on the sieve that do not pass through the sieve of the sieve with a mesh size of Xmm are defined as particles greater than Xmm.

[0042] The prior treatment of the solid carbon resource is implemented as needed. For example, in the mixing process described later, in the case of spreading a petroleum additive on the solid carbon resource, the prior treatment of the solid carbon resource is not necessarily required. In the case of using a container, a mixer, etc. for mixing, in order to make the solid carbon resource and the petroleum additive more uniformly mixed, the solid carbon resource is pre-treated, and the average particle size of the solid carbon resource is preferably set to more than 0.5 times and within 1.5 times the average particle size of the petroleum additive, and more preferably set to the same degree as the average particle size of the petroleum additive (more than 0.8 times and within 1.2 times). That is, the average particle size of the solid carbon resource is preferably set to more than 0.5 times the average particle size of the petroleum additive, and more preferably set to more than 0.8 times. The average particle size of the solid carbon resource is further preferably set to within 1.5 times the average particle size of the petroleum additive, and more preferably set to within 1.2 times. Here, the average particle size refers to the arithmetic mean particle size calculated by measuring the sample mass wi of each particle size segment i using a specified sieve with different meshes (opening sizes), and weighting the representative value of each particle size segment by the mass fraction of each particle size segment.

[0043] (Petroleum additive adding process)

[0044] The petroleum additive adding step is a step of adding a petroleum additive to the solid carbon resource as a natural exotherm suppressor. The petroleum additive adding step is preferably a step of adding the petroleum additive to the solid carbon resource as a natural exotherm suppressor at a temperature of 20 to 80°C.

[0045] When a pre-treated petroleum additive is added to a pre-treated solid carbon resource, the amount of the petroleum additive added relative to the solid carbon resource is set to 0.1% or more, preferably 1.0% or more, and more preferably 5.0% or more in terms of mass ratio. If the amount of the petroleum additive is too small, the natural heat release suppression effect of the solid carbon resource cannot be obtained. There is no upper limit to the amount of the petroleum additive added, but from a cost perspective, it is preferably 40% or less, more preferably 30% or less, and further preferably 20% or less in terms of mass ratio relative to the solid carbon resource. The petroleum additive is added, for example, by putting the solid carbon resource and the petroleum additive into a mixer. The temperature for adding the petroleum additive to the solid carbon resource is preferably 80°C or less, more preferably 60°C or less, and more preferably 40°C or less. There is no need to set a lower limit temperature, but from the actual operating conditions, it is preferably 10°C or more, and more preferably 20°C or more.

[0046] (Mixing process)

[0047] The mixing process is a process of mixing the solid carbon resource with the petroleum-based additive. The mixing process is a process performed after the petroleum-based additive is added to the solid carbon resource, and the petroleum-based additive is fully mixed in such a way that the petroleum-based additive becomes equal to the solid carbon resource. When the solid carbon resource is a small amount, the two (solid carbon resource and petroleum-based additive) are placed in a container and sealed, and the mixture is shaken. When the solid carbon resource is a large amount, the two are put into a mixer, etc., and the mixture is shaken or rotated. When processing a larger amount of solid carbon resources, in addition to using a mixer, etc., the petroleum-based additive can also be scattered in the solid carbon resource (for example, solid carbon resources in the process of piling up in the material yard, solid carbon resources in the state of being stored in the material yard, etc.). By spreading it in the solid carbon resource, the above-mentioned adding process and mixing process can be implemented at one time. In addition, after spreading, additional mixing treatment can be performed using heavy equipment, etc.

[0048] (Storage process)

[0049] The storage process involves storing solid carbon resources to which petroleum-based additives have been added. Solid carbon resources to which petroleum-based additives have been added (hereinafter referred to as "added solid carbon resources") have suppressed natural exothermicity, allowing them to be stored for a specified period in stockyards, storage tanks, and the like. Petroleum-based additives are byproducts of heavy petroleum oil or petroleum refining, and have a structure similar to that of fossil fuels. Therefore, solid carbon resources (such as coal) with suppressed exothermicity can be used directly as fuel for power generation or as a raw material for coke production.

[0050] The present invention provides a method for suppressing the natural exotherm of solid carbon resources, including the step of adding a petroleum-based additive to the solid carbon resource, and a method for storing the solid carbon resource using the same. According to the present invention, the petroleum-based additive is a byproduct of heavy petroleum oil or petroleum refining and is therefore available at a low cost. Simply adding the petroleum-based additive to the solid carbon resource achieves a natural exotherm suppression effect, making the process simple to perform.

[0051] <Second embodiment>

[0052] This embodiment further includes a heating step between the mixing step (or the petroleum additive addition step if the mixing step is omitted) and the storage step in the first embodiment. In the first embodiment described above, the addition of the petroleum additive reduced the natural exothermicity of the solid carbon resource. The present inventors have discovered that, after adding the petroleum additive, further heating in an inert gas atmosphere can further suppress the natural exothermicity of the solid carbon resource. The inert gas atmosphere is used because heating in air could potentially cause combustion of the solid carbon resource. Specifically, in the second embodiment, it is preferred that the solid carbon resource pretreatment step and the petroleum additive pretreatment step be performed first, followed by the petroleum additive addition step, the mixing step, the heating step, and finally the storage step. From the perspective of suppressing the natural exothermicity of the solid carbon resource, at least the petroleum additive addition step should be performed. If storage is also performed, the storage step should preferably be performed next. From the perspective of further suppressing the natural exothermicity of the solid carbon resource, the heating step is preferably performed. However, to maximize the benefits of this embodiment, it is preferred to perform each of the above steps. Since the steps other than the heating step are the same as those of the first embodiment, their description will be omitted. The heating step will be described in detail below.

[0053] (Heating process)

[0054] The heating process is a process of heating the solid carbon resource to which a petroleum-based additive has been added under an inert gas atmosphere. That is, in the heating process, the solid carbon resource after addition is put into a heating furnace filled with an inert gas, and the solid carbon resource after addition is heated using the heating furnace. By the heat treatment, the solid carbon resource after addition becomes inactive, and the natural heat release is further reduced. In this heating process, since there is no need to use chemicals, etc., costs can be suppressed. In addition, the supply stability of inert gases such as nitrogen is high, and the operation is simple, so it can be easily handled. In this way, by adding a heating process of heating the solid carbon resource to which a petroleum-based additive has been added under an inert gas atmosphere to the first embodiment, the natural heat release of the solid carbon resource is further reduced, and a relatively low-cost and simple method for suppressing the natural heat release of solid carbon resources and a solid carbon resource storage method using the same can be implemented.

[0055] The heat treatment temperature of the added solid carbon resource can be preferably 20°C or higher, more preferably 40°C or higher, more preferably 60°C or higher, more preferably 80°C or higher, more preferably 120°C or higher, and more preferably 200°C or higher. However, if the heat treatment temperature exceeds the dry distillation temperature during solid carbon resource production, the carbonization of the added solid carbon resource may be accelerated, causing structural changes. Therefore, it is preferable to set the upper limit to the dry distillation temperature during coke production from the added solid carbon resource. For example, the dry distillation temperature is 600-1000°C. Therefore, the heat treatment temperature is preferably 1000°C or lower, more preferably 800°C or lower, and even more preferably 600°C or lower.

[0056] To ensure sufficient progress of the oxidation inhibition reaction, the heat treatment time is preferably set to 1 hour or longer. While there is no upper limit, the heat treatment time can be, for example, 1 hour or longer and 168 hours or shorter, preferably 1 hour or longer and 168 hours or shorter, more preferably 1 hour or longer and 72 hours or shorter, and even more preferably 12 hours or longer and 72 hours or shorter. In other words, the heat treatment time is preferably 1 hour or longer, more preferably 12 hours or longer. Furthermore, the heat treatment time is preferably 168 hours or shorter, more preferably 72 hours or shorter.

[0057] In order to prevent combustion of the solid carbon resource after addition, the atmosphere during the heat treatment is set to an inert gas atmosphere. As the inert gas at this time, nitrogen, argon, etc. can be used.

[0058] Solid carbon resources containing petroleum-based additives are heat-treated in an inert gas atmosphere. Heat treatment changes the structure of the solid carbon resources, rendering them inert and further suppressing their natural exothermicity. Therefore, even if the solid carbon resources are stored directly in a stockyard or storage tank after heat treatment, fires caused by spontaneous combustion can be prevented.

[0059] Example

[0060] The following examples are provided to specifically illustrate the method for suppressing the natural heat release of solid carbon resources according to the present invention. It should be noted that the following examples are merely examples of the method for suppressing the natural heat release of solid carbon resources, and the present invention is not limited to the following examples.

[0061] (Example 1)

[0062] As a solid carbon resource, biochar derived from acacia (acacia wood) with high heat release properties was used. The four tests (Test No. 1 to 4) shown in Table 1 below were evaluated using a natural heat release evaluation device. The carbonization temperature of the biochar used in the test is unknown, but since the temperature of the material at the kiln outlet was 595°C, it was heated to at least 595°C. Petroleum-based additives used petroleum-based asphalt. This petroleum-based asphalt is obtained by thermally decomposing the vacuum distillation residue of petroleum as a raw material using heated steam at 600°C or above. These solid carbon resources and added petroleum-based additives were crushed using a gold rod in a granulation bowl, and classified using two sieves with mesh sizes of 1.0 mm and 1.7 mm. Materials with a particle size range of 1.0 mm or more and less than 1.7 mm (the upper sieve of the sieve with mesh size of 1.0 mm and the lower sieve of the sieve with mesh size of 1.7 mm) were used. To 1 g of the classified biochar, 0 g, 0.05 g, 0.10 g, and 0.20 g of a petroleum-based additive were added at 20° C., respectively, and the mixture was shaken and mixed in a closed container (Test Nos. 1 to 4).

[0063] Table 1

[0064]

[0065] The mixed sample is filled in a sample container built into a spontaneous heat release evaluation device (Spontaneous ignition tester, manufactured by Shimadzu Corporation, SIT-2), and the spontaneous ignition properties of each sample of test No. 1 to 4 are measured using the spontaneous heat release evaluation device. After the atmosphere in the device is replaced with a nitrogen atmosphere, the temperature is raised by external heating until the sample temperature reaches 130°C. After confirming that the sample temperature has reached 130°C, the atmosphere in the device is switched from nitrogen to air, and the external heating is interrupted. This moment is set as the start time of the test, and the temperature-time behavior of the sample caused by natural heat release is confirmed. Specifically, the sample temperature is measured every 5 seconds to obtain a temperature-time (vertical axis-horizontal axis) temperature rise curve.

[0066] Here, it is believed that the temperature rise rate will be delayed by adding petroleum additives due to their large heat capacity. Therefore, it becomes indistinguishable whether the temperature rise rate delay of the temperature rise curve obtained by the natural heat release evaluation device is caused by the heat capacity of the petroleum additive or by the interaction between the petroleum additive and the solid carbon resource. Therefore, by assuming that the temperature rise rate of the petroleum additive and the solid carbon resource is the same and correcting the obtained temperature rise curve, the influence of the temperature rise rate delay caused by the heat capacity of the petroleum additive is eliminated. Specifically, the temperature rise curve obtained by the measurement is differentiated to calculate the temperature rise rate (dT / dt). By dividing the temperature rise rate by the mass of (solid carbon resource + petroleum additive), the temperature rise rate per unit mass of the mixture of solid carbon resource (biochar) and petroleum additive is obtained. For example, when 20% by mass of petroleum additive is added, the temperature rise rate (dT / dt) is divided by 1.2. The temperature rise rate per unit mass of the solid carbon resource is integrated to restore the temperature-time curve (hereinafter also referred to as the corrected temperature rise curve). The natural heat dissipation of each sample was evaluated based on the time taken for the sample temperature to reach 200°C from 130°C as shown by the corrected temperature rise curve (hereinafter referred to as T200). Note that a larger T200 value indicates a more suppressed natural heat dissipation.

[0067] Figure 1 This is a graph showing the corrected temperature rise curves of Test Nos. 1 to 4 (Comparative Example 1, Inventive Examples 1 to 3). Figure 2 The corrected heating curve ( Figure 1 ) are compared with the T200 values ​​calculated by . More specifically, the graph shows the delay time of T200 of each invention example with T200 of Comparative Example 1 as the benchmark (T200 of the invention example - T200 of Comparative Example 1). T200 is shown in Table 1.

[0068] like Figure 2 As shown in , it can be seen from the value of T200 that the natural heat release of Test No. 2 to 4 (Inventive Examples 1 to 3) is all reduced compared to Test No. 1 (Comparative Example 1) in which no petroleum additives are added. It should be noted that in this test, since the sample was preheated to 130°C, the subsequent heating rate became faster (i.e., an accelerated test was performed). Therefore, for example, the difference between T200 of Inventive Example 1 and T200 of Comparative Example 1 is 3 minutes, but it is believed that at the actual storage site (i.e., in an environment where no accelerated test is performed), T200 of Inventive Example 1 is extended by more than 3 minutes compared to T200 of Comparative Example 1. Therefore, Inventive Example 1 fully exerts the effect of suppressing natural heat release.

[0069] (Example 2)

[0070] The same solid carbon resource (biochar from acacia (acacia wood)) and petroleum-based additive (petroleum-based asphalt) as in Example 1 were crushed and classified, and the particle size was set to be within the range of 1.0 mm or more and less than 1.7 mm. For each gram of solid carbon resource (biochar), 0.2 g of petroleum-based additive or 0.05 g of petroleum-based additive was added at every 20°C and mixed. Thereafter, heating was performed for 12 hours under a nitrogen atmosphere at the temperature shown in Table 2 described below. After each sample was cooled to room temperature (20°C), the temperature rise curve of each treated sample was measured using a natural ignition evaluation device (SIT-2) in the same manner as in Example 1, and the same correction as in Example 1 was performed. Figure 3 This is a graph showing the corrected temperature rise curves of Test No. 4 (Invention Example 3) of Example 1 and Test Nos. 5 to 8 (Invention Examples 4 to 7) of Example 2. Figure 4 This graph compares the T200 values ​​calculated from the corrected temperature rise curves for Test No. 4 (Inventive Example 3) of Example 1 and Test Nos. 5 to 7 (Inventive Examples 4 to 6) of Example 2. More specifically, it shows the delay time of T200 for each Inventive Example using T200 of Comparative Example 1 as a benchmark (T200 of Inventive Example - T200 of Comparative Example 1). Table 2 shows T200 (Table 1 shows T200 for Inventive Example 3).

[0071] Table 2

[0072]

[0073] The obtained temperature rise curves show that the higher the heating temperature, the gentler the slope of the corrected temperature rise curve becomes. In particular, when the heating temperature is 80°C or above (Inventive Examples 5 to 7), the slope becomes significantly gentler, and the natural heat release is greatly reduced. In addition, in Inventive Example 7 (heating temperature is 200°C), due to the following Figure 3 As shown in , the exothermicity is reduced, so T200 cannot be calculated. From these facts, it is believed that the higher the heat treatment temperature, the more the chemical interaction between the petroleum additive and the solid carbon resource is promoted, and the effect of suppressing the exothermicity is enhanced.

[0074] Furthermore, if Invention Example 8 of Example 2 is compared with Invention Example 3 of Example 1, Invention Example 8 that has been subjected to heat treatment has a larger T200 value than Invention Example 3 that has been subjected to no heat treatment and has a larger amount of petroleum additives added, thereby suppressing the natural exotherm. From the above, it can be said that by performing a heat treatment process, even if the amount of petroleum additives added is reduced, the effect of suppressing the natural exotherm can be obtained. It should be noted that, when Invention Example 3 is compared with Invention Example 4, T170 (the time it takes for the sample temperature to reach 170°C from 130°C) of Invention Example 4 is longer than T170 of Invention Example 3. Therefore, the heat treatment process of Invention Example 4 fully exerts the effect of suppressing the natural exotherm.

[0075] While preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to these examples. Anyone with ordinary knowledge in the technical field to which the present invention pertains will readily appreciate that various variations and modifications are conceivable within the scope of the technical concept recited in the claims, and such variations and modifications naturally fall within the technical scope of the present invention.

Claims

1. A method for suppressing the natural exotherm of a solid carbon resource, comprising the step of adding a petroleum-based additive to the solid carbon resource as a natural exotherm suppressor.

2. The method for suppressing natural heat release of solid carbon resources according to claim 1, wherein: The petroleum-based additive is added to the solid carbon resource in an amount of 1% by mass or more.

3. The method for suppressing natural heat generation of a solid carbon resource according to claim 1, further comprising the step of heating the solid carbon resource to which the petroleum-based additive has been added at a temperature of 20°C or higher for 1 hour or longer in an inert gas atmosphere.

4. A method for storing solid carbon resources, wherein: The solid carbon resource treated by the method according to any one of claims 1 to 3 is stored.

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