Methods for disposing of rubber waste

Abstract

This invention provides a method for treating rubber waste that can gasify not only the rubber components but also the carbon black, even in rubber waste containing carbon black, thereby improving the gas generation rate of useful generated gases. [Solution] The method for processing rubber waste includes the steps of: preparing a material to be processed derived from rubber waste containing either natural rubber or synthetic rubber, or both, and carbon black; a thermal decomposition step in which the material to be processed is thermally decomposed at a temperature of 850°C to 1300°C in a reducing atmosphere in which O2 gas is 5% by volume or less and H2O gas is 0.1% by volume or more and 20% by volume or less; and a recovery step in which the generated gas mainly composed of H2 gas, CO gas, and CO2 gas produced by the thermal decomposition step is recovered.

Description

Technical Field

[0001] The present invention relates to a method for treating rubber waste.

Background Art

[0002] Generally, for rubber products, vulcanized rubber obtained by crosslinking a polymer such as polyisoprene by vulcanization is used. Additives such as a reinforcing material, an accelerator for promoting the crosslinking reaction, and a plasticizer for improving processability are further added to the vulcanized rubber to impart additional functions and improve the performance. Therefore, it can be said that the vulcanized rubber, which is the material of rubber products, is composed not only of covalent bonds but also of other complex interactions caused by these additives.

[0003] Due to the above-mentioned complex interactions, it is extremely difficult to recycle rubber waste derived from used rubber products by material recycling or chemical recycling. Specifically, most rubber wastes such as waste tires contain the above-mentioned complex interactions and are difficult to decompose. Therefore, it is difficult to recycle them by material recycling or chemical recycling. Although recycling is carried out as recycled rubber in limited areas such as automotive parts, most are actually incinerated as part of thermal recycling.

[0004] For example, as a method for treating rubber waste (waste rubber) such as waste tires, waste rubber reinforced with metal and carbon black is charged from the upper part of a decomposition furnace, and this waste rubber is dried and thermally decomposed by high-temperature gas rising in the furnace. While recovering pyrolysis gas from the upper part, metal is melted by dropping a residue mainly composed of carbon and metal toward the lower part of the furnace, and a method for treating waste rubber aimed at recovering molten metal from the bottom of the furnace is known (see Patent Document 1).

[0005] Furthermore, a method for decomposing crosslinked rubber aimed at improving the yield of recycled monomers is known, which includes a first decomposition step of thermally decomposing crosslinked rubber containing a rubber component containing diene rubber at 150°C to 400°C, and a second decomposition step of further thermally decomposing the decomposition product obtained in the first decomposition step in an inert gas atmosphere and in the absence of a catalyst at 600°C to 950°C (see Patent Document 2). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 56-41293 [Patent Document 2] International Publication No. 2023 / 153377 [Overview of the project] [Problems that the invention aims to solve]

[0007] According to the technology described in Patent Document 1, the sole purpose is to recover the mixed metal as molten metal, and the recovery and reuse of gaseous products are not envisioned. Therefore, from the standpoint of effective resource utilization, it is not sufficient. Furthermore, according to the technology described in Patent Document 2, components such as carbon black cannot be decomposed, and therefore, from the standpoint of efficient resource utilization, it cannot be said to be sufficient. Therefore, the object of the present invention is to provide a method for treating rubber waste that can gasify not only the rubber components but also the carbon black, even in rubber waste containing carbon black, and can further improve the gas generation rate of useful generated gases. [Means for solving the problem]

[0008] The present invention provides the following [1] to

[10] . [1] A process of preparing a material to be treated from rubber waste containing either natural rubber or synthetic rubber, or both, and carbon black, The process involves a thermal decomposition step in which the material to be treated is thermally decomposed at a temperature of 850°C to 1300°C in a reducing atmosphere in which O2 gas is present in an amount of 5% or less by volume and H2O gas is present in an amount of 0.1% to 20% by volume. A recovery step for recovering the generated gas, mainly composed of H2 gas, CO gas, and CO2 gas, produced by the aforementioned pyrolysis step. A method for disposing of rubber waste, including [specific material / material]. [2] The method for processing rubber waste according to [1], wherein the step of preparing the material to be processed further includes a step of crushing the rubber waste to prepare a material to be processed that includes crushed rubber. [3] The process of preparing the material to be processed further includes crushing the rubber waste, which further includes metal members, to prepare the material to be processed, which includes the metal members, crushed metal members, and crushed rubber, The method for treating rubber waste according to [2], wherein the recovery step is a step of independently recovering the generated gas, the metal member and the metal derived from the crushed metal member. [4] The method for treating rubber waste according to any one of [1] to [3], wherein the thermal decomposition step is a step of thermally decomposing the material to be treated at a temperature of 900°C or more and 1200°C or less. [5] The method for treating rubber waste according to any one of [1] to [4], wherein the thermal decomposition step is a step of thermally decomposing the material to be treated in a reducing atmosphere in which the amount of O2 gas is 2.5 volume% or less and the amount of H2O gas is 0.5 volume% or more and 10 volume% or less. [6] The method for treating rubber waste according to any one of [1] to [5], wherein the thermal decomposition step is a step of thermally decomposing the object to be treated at a temperature of 900°C to 1200°C and in a reducing atmosphere in which the amount of O2 gas is 2.5% by volume or less and the amount of H2O gas is 0.5% by volume or more to 10% by volume. [7] The method for treating rubber waste according to any one of [1] to [6], wherein the recovery step is a step of recovering a generated gas in which the gas generation rate of H2 gas is 30% or more and 70% or less when the sum of the gas generation rates of H2 gas, CO gas, and CO2 gas is 100%. [8] The method for treating rubber waste according to any one of [1] to [7], wherein the recovery step is a step of recovering a generated gas in which the gas generation rate of H2 gas is 40% or more and 70% or less when the sum of the gas generation rates of H2 gas, CO gas, and CO2 gas is 100% by volume. [9] A method for treating rubber waste according to any one of [1] to [8], further comprising a synthesis step of introducing the generated gas recovered in the recovery step into a culture tank in which anaerobic bacteria are cultured, to synthesize one or more selected from the group consisting of isoprene-containing terpenes, polyisoprenes, ethanol, methane, and methanol.

[10] The method for treating rubber waste according to [9], wherein the synthesis step is a step of synthesizing either isoprene or ethanol or both. [Effects of the Invention]

[0009] According to the present invention, even rubber waste containing carbon black can be gasified, not only the rubber components but also the carbon black, reducing the generation of hydrocarbons while gasifying, and providing a method for treating rubber waste that can further improve the gas generation rate of useful generated gases, particularly H2 gas. [Modes for carrying out the invention]

[0010] The following describes in detail a method for processing rubber waste according to embodiments of the present invention. The present invention is not limited by the following description, and each component can be modified as appropriate without departing from the spirit of the invention.

[0011] 1. Methods for disposing of rubber waste The method for treating rubber waste according to an embodiment of the present invention includes a step of preparing a treatment object derived from rubber waste containing one or both of natural rubber and synthetic rubber and carbon black, a pyrolysis step of pyrolyzing the treatment object in a reducing atmosphere at a temperature of 850°C or higher and 1300°C or lower, where the O2 gas is 5% by volume or less and the H2O gas is 0.1% by volume or more and 20% by volume or less, and a recovery step of recovering the product gas mainly composed of H2 gas, CO gas, and CO2 gas generated in the pyrolysis step. The method for treating rubber waste includes these steps.

[0012] Hereinafter, the steps that may be included in the method for treating rubber waste according to the present embodiment, the materials that may be used in such steps, and the conditions will be specifically described.

[0013] (1) Step of preparing a treatment object derived from rubber waste containing one or both of natural rubber and synthetic rubber and carbon black In the present embodiment, the treatment object to be subjected to the method for treating rubber waste is a treatment object derived from rubber waste containing one or both of natural rubber and synthetic rubber and carbon black.

[0014] The treatment object is not particularly limited as long as it is derived from rubber waste containing one or both of natural rubber and synthetic rubber and carbon black.

[0015] In the present embodiment, the rubber contained in the rubber waste may be either vulcanized rubber or unvulcanized rubber.

[0016] In the present embodiment, the treatment object may contain, for example, silica in addition to rubber and carbon black.

[0017] Examples of rubber waste containing carbon black include, specifically, waste tires, used engine mounts, suspension bushes, rubber hoses, muffler hangers, rubber stoppers, vibration isolators, dampers for housing, waste plastics that may contain synthetic rubber such as rolls and blades of copying machines, rubber scraps that may contain natural rubber such as cut waste and ebonite scraps, and further waste containing both synthetic rubber and natural rubber.

[0018] In this embodiment, the rubber waste can be used as a processing object as it is without any additional treatment. The size of the processing object is not particularly limited as long as the pyrolysis process described later can be carried out. Also, a processed product obtained by performing one or more additional treatments selected from the group consisting of desulfurization, washing, dust removal, crushing, separation, and sorting on the rubber waste can be used as the processing object. Specifically, for example, after crushing the rubber waste or during the crushing process, the dust generated during the crushing process can be removed by suction, or the rubber waste can be washed to obtain a cleaner processing object.

[0019] Specifically, for example, if there are circumstances such that the size of the processing object is too large to be applied to the pyrolysis process when performing the pyrolysis process, the step of preparing the processing object may further include a process of crushing the rubber waste to prepare a processing object containing rubber crushed material.

[0020] Also in this embodiment, for example, when the rubber waste contains a rubber waste in which a metal member and a rubber member are adhered and integrally formed, in order to make it the optimal size as the processing object as already described, and further to separate the metal member and the rubber member, a crushing process of crushing the rubber waste can be performed. When it is necessary to separate the metal member and the rubber member, prior to the crushing process, for example, a dissolution removal process for removing the adhesive layer that adheres the metal member and the rubber member may be performed.

[0021] The dissolution and removal process can be carried out using conventionally known and suitable equipment, such as a solvent tank or electromagnetic induction tank, which uses a conventionally known and suitable solvent capable of dissolving adhesives, such as methylene chloride or formic acid.

[0022] In other words, the process of preparing the material to be processed may further include crushing the rubber waste, which further contains metal members, to prepare the material to be processed, which contains the metal members, crushed metal members, and crushed rubber.

[0023] Furthermore, in this embodiment, the step of preparing the material to be processed may further include a process of separating and sorting, for example, only the rubber material and crushed rubber material from the metal material and rubber material separated by the crushing process described above.

[0024] In this embodiment, the apparatus for performing the crushing process (hereinafter referred to as the crushing apparatus), which is a process of crushing rubber waste to prepare a material for processing, is not particularly limited, as long as it can prepare a material suitable for the pyrolysis process.

[0025] In this embodiment, the crushing process can be carried out using any suitable conventionally known crushing device. Suitable examples of crushing devices include chain mills, knife mills, hammer mills, jet mills, and other media mills.

[0026] (2) A thermal decomposition step in which the material to be processed is thermally decomposed at a temperature of 850°C to 1300°C in a reducing atmosphere in which the O2 gas is 5% by volume or less and the H2O gas is 0.1% by volume or more and 20% by volume or less. First, we will describe the "thermal decomposition apparatus" that can be used to carry out the thermal decomposition process of this embodiment.

[0027] The pyrolysis apparatus of this embodiment can be any conventionally known apparatus with any suitable configuration, provided that it can pyrolyze the material to be processed at a temperature of 850°C to 1300°C, in a reducing atmosphere in which O2 gas is 5% by volume or less and H2O gas is 0.1% by volume or more and 20% by volume or less.

[0028] In this embodiment, suitable pyrolysis apparatuses include extruders having any suitable configuration known conventionally, as well as gasification furnaces such as fluidized bed gasification furnaces, kiln-type gasification furnaces, and shaft-type gasification furnaces.

[0029] In this embodiment, the pyrolysis apparatus is preferably an extruder or gasification furnace equipped with an atmosphere adjustment means that can supply steam (H2O gas) into the pyrolysis apparatus (furnace) and further adjust the composition of the atmosphere (gasflow) inside the pyrolysis apparatus (furnace). Here, any conventionally known and suitable configuration can be adopted as the atmosphere adjustment means, including cylinders, pumps and piping.

[0030] In the pyrolysis process of this embodiment, the temperature for pyrolysis of the material to be treated (referred to as the pyrolysis temperature) is preferably 850°C or higher, particularly from the viewpoint of pyrolyzing and gasifying not only the rubber components contained in the material to be treated (rubber waste) but also the carbon black. It is more preferably 900°C or higher, particularly from the viewpoint of reducing the amount of hydrocarbons generated and further improving the amount and / or rate of H2 gas generated. It is preferably 1300°C or lower, particularly from the viewpoint of pyrolyzing and gasifying not only the rubber components contained in the material to be treated (rubber waste) but also the carbon black. It is more preferably 1200°C or lower, particularly from the viewpoint of reducing the amount of hydrocarbons generated and further improving the amount and / or rate of H2 gas generated.

[0031] In the pyrolysis process of this embodiment, the temperature for pyrolysis of the material to be treated is preferably 850°C to 1300°C, particularly from the viewpoint of pyrolysis and gasification of not only the rubber components contained in the material to be treated (rubber waste) but also the carbon black. More preferably, the temperature is 900°C to 1200°C, particularly from the viewpoint of reducing the amount of hydrocarbons generated and further improving the amount and / or rate of H2 gas generated.

[0032] In this embodiment, the pyrolysis process is carried out under a reducing atmosphere. Here, there is a correlation between the total amount of product gas and the amount of H2 gas in the product gas (the rate of H2 gas generation in the product gas), and the amount of O2 gas and / or H2O gas in the reducing atmosphere. In other words, by adjusting the amount of O2 gas and / or H2O gas in the reducing atmosphere, the total amount of product gas and furthermore the amount of H2 gas (the rate of H2 gas generation in the product gas) can be adjusted. Specifically, by adjusting the amount of O2 gas and / or H2O gas in the reducing atmosphere to increase it, the reaction is further promoted, and as a result, the total amount of product gas and furthermore the amount of H2 gas (the rate of H2 gas generation in the product gas) can be adjusted to increase it.

[0033] In this embodiment, the pyrolysis process is preferably carried out by adjusting the atmosphere (airflow) inside the pyrolysis apparatus (furnace) so that the O2 gas is 5% by volume or less, i.e., at most 5% by volume or less. More preferably, from the viewpoint of reducing the amount of hydrocarbons generated and, in particular, further improving the amount and / or rate of H2 gas generated, the process is carried out in an atmosphere adjusted so that the O2 gas is 2.5% by volume or less, i.e., at most 2.5% by volume or less. It may also be carried out in an atmosphere adjusted so that the O2 gas is 0% by volume.

[0034] In the reducing atmosphere in which the pyrolysis process of this embodiment is carried out, it is preferable to adjust the atmosphere (airflow) inside the pyrolysis apparatus (furnace) so that the H2O gas content is 0.1 volume% or more. More preferably, from the viewpoint of reducing the amount of hydrocarbons generated and, in particular, further improving the amount and / or rate of H2 gas generated, it is preferable to carry out the process in an atmosphere adjusted so that the H2O gas content is 0.5 volume% or more. It is preferable to adjust the atmosphere (airflow) inside the pyrolysis apparatus (furnace) so that the H2O gas content is 20 volume% or less. Since a great deal of energy is required to generate H2O gas, it is preferable to carry out the process in an atmosphere adjusted so that the H2O gas content is 10 volume% or less, from the viewpoint of adjusting the balance between the amount (rate) of generated gas containing H2 gas and the cost of implementation, making the pyrolysis process easier to carry out, and improving energy efficiency.

[0035] In the reducing atmosphere in which the pyrolysis process of this embodiment is carried out, it is preferable to adjust the atmosphere (airflow) inside the pyrolysis apparatus (furnace) so that the amount of H2O gas is 0.1% to 20% by volume. From the viewpoint of reducing the amount of hydrocarbons generated, particularly improving the amount and / or rate of H2 gas generated, and further balancing the amount (rate) of generated product gas containing H2 gas with the cost of implementation, making the pyrolysis process simpler and improving energy efficiency, it is even more preferable to carry out the process in an atmosphere adjusted so that the amount of H2O gas is 0.5% to 10% by volume.

[0036] In this embodiment, it is preferable that the pyrolysis process is carried out at a temperature of 900°C to 1200°C, and in a reducing atmosphere in which the O2 gas is 2.5% by volume or less and the H2O gas is 0.5% by volume or less.

[0037] In this embodiment, the pyrolysis step can be a step that includes two or more pyrolysis treatments with different conditions, namely the pyrolysis temperature, and the amount of O2 gas and / or H2O gas in the reducing atmosphere, as described above. Specifically, for example, the pyrolysis step can include a first pyrolysis treatment in which the target material to be treated is first pyrolyzed and gasified, and then a second pyrolysis treatment in which by-products, such as oily components (tar) and hydrocarbons, that are inevitably produced by the first pyrolysis treatment are pyrolyzed and gasified. Here, the first pyrolysis treatment and the second pyrolysis treatment may be carried out continuously or intermittently.

[0038] The pyrolysis step of this embodiment may be carried out in the presence of any suitable catalyst that is conventionally known, with the aim of more efficiently pyrolyzing and gasifying the material to be treated. Examples of catalysts that can be used include nickel-based catalysts such as nickel and nickel oxide, ruthenium-based catalysts, iron-based catalysts, cobalt-based catalysts, titanium-based catalysts, and oxide-based catalysts.

[0039] (3) Recovery process for recovering the generated gas, mainly consisting of H2 gas, CO gas, and CO2 gas, produced by the thermal decomposition process (recovery process) In this embodiment, the recovery step is a step of recovering the H2 gas, CO gas, and product gas mainly composed of CO2 gas generated by the pyrolysis step described above.

[0040] In this embodiment, the generated gas recovered by the recovery step is preferably a generated gas in which the proportion of H2 gas generation rate is 30% or more, more preferably 35% or more, even more preferably 40% or more, particularly preferably 45% or more, preferably 70% or less, more preferably 65% ​​or less, and even more preferably 60% or less.

[0041] In this embodiment, the generated gas recovered by the recovery step is preferably a generated gas in which the proportion of H2 gas generation rate is 30% or more and 70% or less when the sum of the gas generation rates of H2 gas, CO gas, and CO2 gas is set to 100%, more preferably a generated gas in which the proportion of H2 gas generation rate is 35% or more and 70% or less when the sum of the gas generation rates of H2 gas, CO gas, and CO2 gas is set to 100% by volume%, and even more preferably a generated gas in which the proportion of H2 gas generation rate is 40% or more and 70% or less when the sum of the gas generation rates of H2 gas, CO gas, and CO2 gas is set to 100% by volume.

[0042] Here, "gas generation rate" is a parameter calculated using the following formula. Formula: Generation rate (%) of each gas in the generated gas = Amount of each gas generated (L) / Σ(Amount of each gas generated excluding N2 and O2 gas (L)) × 100

[0043] The "amount of gas generated" in the above formula can be calculated, for example, by following the procedure in 1) to 3) below. 1) Calculate the N2 gas concentration (%) in the generated gas using the following formula. Formula: N2 gas concentration (%) in the generated gas = 100 - Σ (analysis results of each gas) 2) Calculate the flow rate (L / min) of the generated gas using the following formula. Formula: Flow rate of generated gas (L / min) = Total flow rate of supplied gas (L / min) × Analysis result of each gas / 100 × Time of pyrolysis (min) 3) The amount of gas generated is calculated using the following formula. Formula: Amount of gas (each gas) generated (L) = Flow rate of generated gas (L / min) × Analysis result of each gas × Time of thermal decomposition (min) Note that "analysis results for each gas" refers to the analysis results (quantity of each gas) obtained for each gas using the analysis methods shown in Table 1 below.

[0044] In the above procedure for calculating the "gas generation rate," the N2 gas concentration (%) in the generated gas may be obtained directly by conventionally known and suitable measurement means and methods, rather than by calculation based on the above formula.

[0045] The gas produced by the rubber waste treatment method of this embodiment includes, in addition to the H2 gas, CO gas, and CO2 gas already described, trace amounts of hydrocarbons (e.g., CH4, C2H4, C2H6, C3H8, isobutane, butane), and even very trace amounts of H2S gas and SO2. x Gas, HCl gas, NO x It may contain gas, including O2 gas.

[0046] According to the rubber waste treatment method of this embodiment, even if the rubber waste contains carbon black, by supplying H2O gas as already described, not only the rubber components but also the carbon black can be effectively gasified. Compared to, for example, the treatment of plastics (waste plastics), the amount (concentration) of hydrocarbons in the generated gas can be reduced, and in particular, the gas generation rate of useful generated gases such as H2 gas can be further improved.

[0047] Furthermore, if the treatment method of this embodiment is intended to be used for rubber waste containing metal components, the recovery step can be a step in which the generated gas and the metal derived from the metal components and crushed metal components are recovered independently of each other.

[0048] The recovery of the generated gas may be carried out simultaneously with the recovery of metals derived from the metal components and crushed metal components, or it may be carried out at different times from the recovery of the metals.

[0049] According to the processing method of this embodiment, since the thermal decomposition process is carried out in a reducing atmosphere, oxidation of the metal during the thermal decomposition process can be prevented, and non-oxidized metal can be efficiently recovered.

[0050] Furthermore, according to the processing method of this embodiment, H2 gas, which is particularly useful as a raw material for the synthesis of useful organic compounds such as methane by methanation, as a raw material for various chemical substances and industrial products, and even as fuel for fuel cells, can be obtained more effectively.

[0051] In this embodiment of the processing method, the target material for processing is assumed to be rubber waste containing rubber and carbon black. However, this embodiment of the processing method can be applied not only to rubber waste, but also to target materials that can generate a relatively large amount of fixed carbon, such as biomass waste, and even waste plastics (resins).

[0052] Furthermore, the generated gas satisfying the above requirements according to the present invention can be suitably applied to the cultivation of a predetermined anaerobic bacterium, in other words, to the synthesis of a useful predetermined substance by culturing anaerobic bacteria, without any particular adjustment of the components of the obtained generated gas.

[0053] Specifically, the processing method of this embodiment may further include a synthesis step in which the generated gas recovered in the recovery step is introduced into a culture tank in which anaerobic bacteria are cultured, and one or more substances selected from the group consisting of terpenes including isoprene, polyisoprenes, ethanol, methane, and methanol are synthesized. In the processing method of this embodiment, the synthesis step is preferably a step in which either isoprene or ethanol, or both, are synthesized. That is, the synthesis step of this embodiment can be a step in which two or more substances selected from the above example group are synthesized simultaneously or individually. Specifically, in the synthesis step of this embodiment, isoprene and methanol can be synthesized simultaneously.

[0054] More specifically, if the synthesis step of this embodiment is, for example, a step to synthesize "isoprene and methanol", it is preferable to use, for example, Clostridium autoetha nogenum as the anaerobic bacterium, the pyrolysis step is preferably carried out at a temperature of 900°C to 1300°C and with an O2 gas content of 0.5% by volume or less, and the recovery step is preferably carried out as a step to recover the generated gas in which the gas generation rate of H2 gas is 30% to 70% when the sum of the gas generation rates of H2 gas, CO gas, and CO2 gas is 100% by volume.

[0055] Furthermore, if the synthesis step in this embodiment is, for example, a step to synthesize "ethanol," it is preferable that the pyrolysis step be carried out at a temperature of 900°C to 1300°C and with an O2 gas content of 0.5% by volume or less, and that the recovery step be carried out as a step to recover the generated gas in which the gas generation rate of H2 gas is 30% to 70% when the sum of the gas generation rates of H2 gas, CO gas, and CO2 gas is 100% by volume.

[0056] Furthermore, if the synthesis step in this embodiment is, for example, a step to synthesize "methane," it is preferable that the pyrolysis step be carried out at a temperature of 900°C to 1300°C and with an O2 gas content of 0.5% or less, and that the recovery step be carried out as a step to recover the generated gas in which the gas generation rate of H2 gas is 70% to 80% when the sum of the gas generation rates of H2 gas, CO gas, and CO2 gas is 100% by volume.

[0057] As described above, the generated gas recovered by the recovery process of this embodiment can be used for the synthesis of useful substances such as isoprene and ethanol by culturing a predetermined anaerobic bacterium without any particular adjustment of the components contained in the generated gas. Furthermore, by purifying and separating, for example, only H2 gas from the generated gas using a conventionally known and suitable purification method, it can be applied to various uses. In this embodiment, it is assumed that the generated gas will be used without any particular adjustment of its components, but adjustments to reduce the amount (concentration) of specific components that are unnecessary or harmful may be made using a conventionally known and suitable method.

[0058] Here, the generated gas recovered in the recovery process may be subjected to a treatment to adjust its temperature to a suitable temperature range using a conventionally known and suitable temperature control means, for example, before being used for culturing anaerobic bacteria.

[0059] Furthermore, if the generated gas contains substances harmful to the selected anaerobic bacteria (e.g., sulfur, chlorine), a conventionally known and suitable removal treatment may be performed to remove the harmful gas from the generated gas supplied to the anaerobic bacteria.

[0060] Furthermore, the generated gas recovered in the recovery process may be temporarily stored in any suitable conventional storage and preservation means before being used, for example, for culturing anaerobic bacteria. [Examples]

[0061] The present invention will be described below with reference to examples. The present invention is not limited to the following examples.

[0062] Example 1 (i) Preparation of pyrolysis equipment and samples First, a pyrolysis apparatus was prepared for use in pyrolysis, comprising an alumina furnace tube (50 mm inner diameter x 1500 mm length) and a horizontal tubular furnace positioned to cover the central part of this furnace tube along its length.

[0063] Next, a rubber compound sample (Sample 1) was prepared as a sample corresponding to the "material to be treated derived from rubber waste," which was molded into uniform particles with a maximum length of approximately 1.5 cm. Note that Sample 1 used in Example 1 contains natural rubber and carbon black, and also contains vulcanized rubber.

[0064] (ii) thermal decomposition First, the furnace tube was heated to 1000°C in a horizontal tubular furnace and maintained there. N2 gas and O2 gas were supplied from cylinders, and distilled water was supplied as steam via a vaporizer to create an atmosphere inside the furnace tube consisting of 0% O2 gas, 90% N2 gas, and 10% H2O gas (a reducing atmosphere). The atmosphere flow rate was set to 5 L / min.

[0065] Next, an alumina boat containing 2g of Sample 1, as previously described, was inserted into the furnace tube (and horizontal tubular furnace) from one end (inlet side). The temperature was increased to 1200°C at a rate of 10°C / min, and Sample 1 was thermally decomposed and gasified for 38 minutes.

[0066] The generated gas, resulting from the thermal decomposition and gasification of Sample 1, was discharged from the other end (outlet side) of the reactor tube and collected in a gas bag using a pump.

[0067] (iii) Analysis of the generated gas The generated gas from sample 1 was analyzed using the conventionally known analytical methods shown in Table 1 below. The results are shown in Tables 2 and 3 below.

[0068] [Table 1]

[0069] Example 2 Pyrolysis was carried out in the same manner as in Example 1, described above, except that the concentration of H2O gas in the atmosphere flowing through the core tube was set to 3% by volume, and the components of the generated gas were analyzed. The results are shown in Tables 2 and 3 below.

[0070] Example 3 Pyrolysis was carried out in the same manner as in Example 1, which was already described, except that the temperature of the reactor core tube was set to 900°C, and the components of the generated gas were analyzed. The results are shown in Tables 2 and 3 below.

[0071] Example 4 Pyrolysis was carried out in the same manner as in Example 3, which was already described, except that the concentration of H2O gas in the atmosphere flowing through the reactor tube was set to 3% by volume, and the generated gas was analyzed. The results are shown in Tables 2 and 3 below.

[0072] Comparative Example 1 Except for using a homogeneous sample (Sample 2) obtained by freeze-pulverizing RPF (Refuse Paper & Plastic Fuel: a solid fuel mainly composed of waste plastics) into a powder, thermal decomposition was carried out in the same manner as in Example 1 described above, and the components of the generated gas were analyzed. The results are shown in Tables 2 and 3 below.

[0073] [Table 2]

[0074] [Table 3]

[0075] The "gas generation rate" shown in Table 3 was calculated using the following formula. Formula: Gas generation rate (%) = Amount of gas generated (L) / Σ(Amount of each gas generated excluding N2 and O2 gas (L)) × 100

[0076] The procedure for calculating the "amount of gas generated" is as follows (1) to (3) below. 1) Calculate the N2 gas concentration (%) in the generated gas using the following formula. N2 gas concentration (%) in the generated gas = 100 - Σ (analysis results of each gas) 2) Calculate the flow rate (L / min) of the generated gas using the following formula. Flow rate of generated gas (L / min) = Total flow rate of supplied gas (L / min) × Analysis result of each gas / 100 × Time of thermal decomposition (min) 3) The amount of gas generated is calculated using the following formula. Amount of gas (each gas) generated (L) = Flow rate of generated gas (L / min) × Analysis result of each gas × Time of thermal decomposition (min) Here, "analysis results for each gas" refers to the analysis results (quantity of each gas) obtained for each gas using the analysis methods shown in Table 1 above.

[0077] According to Examples 1 to 4 of the processing method of the present invention described above, rubber waste, including carbon black, can be gasified. Compared to Comparative Example 1, which uses RPF, for example, gasification can be performed while reducing the generation of hydrocarbons, and the gas generation rate of H2 gas in particular can be further improved.

Claims

1. A process for preparing a material to be treated derived from rubber waste containing either natural rubber or synthetic rubber, or both, and carbon black, The object to be processed is heated at a temperature of 850°C to 1300°C. ２ The gas is 5% by volume or less, H ２ A thermal decomposition step in which O gas is thermally decomposed in a reducing atmosphere in which O gas is present in an amount of 0.1 volume% to 20 volume%, H produced by the aforementioned thermal decomposition step ２ Gas, CO gas, and CO ２ A recovery process for recovering the generated gas, which is mainly composed of gas, and A method for disposing of rubber waste, including [specific material / material].

2. The method for processing rubber waste according to claim 1, wherein the step of preparing the material to be processed further includes a step of crushing the rubber waste to prepare a material to be processed that includes crushed rubber.

3. The process of preparing the material to be processed further includes crushing the rubber waste, which further includes metal members, to prepare the material to be processed, which includes the metal members, crushed metal members, and crushed rubber. The method for processing rubber waste according to claim 2, wherein the recovery step is a step of independently recovering the generated gas, the metal member, and the metal derived from the crushed metal member.

4. The method for treating rubber waste according to any one of claims 1 to 3, wherein the thermal decomposition step is a step of thermally decomposing the object to be treated at a temperature of 900°C or more and 1200°C or less.

5. The thermal decomposition step processes the object to be treated, O ２ The gas is 2.5% by volume or less, H ２ A method for treating rubber waste according to any one of claims 1 to 3, comprising the step of thermal decomposition in a reducing atmosphere in which oxygen gas is present in an amount of 0.5 volume% or more and 10 volume% or less.

6. The thermal decomposition step involves heating the object to be treated at a temperature of 900°C to 1200°C, and then o ２ The gas is 2.5% by volume or less, H ２ A method for treating rubber waste according to any one of claims 1 to 3, comprising the step of thermal decomposition in a reducing atmosphere in which oxygen gas is present in an amount of 0.5 volume% or more and 10 volume% or less.

7. The recovery step is H ２ gas, CO gas, and CO ２ When the total gas generation rate of the gas is 100%, the process of recovering the generated gas in which the proportion of the gas generation rate of H ２ gas is 30% or more and 70% or less, The method for treating rubber waste according to any one of claims 1 to 3.

8. The aforementioned recovery process is H ２ Gas, CO gas, and CO ２ When the sum of the gas generation rates of the gases is set to 100 volume%, H ２ A method for treating rubber waste according to any one of claims 1 to 3, comprising a step of recovering generated gas in which the gas generation rate of the gas is 40% or more and 70% or less.

9. A method for treating rubber waste according to any one of claims 1 to 3, further comprising a synthesis step of introducing the generated gas recovered in the recovery step into a culture tank in which anaerobic bacteria are cultured, and synthesizing one or more selected from the group consisting of isoprene-containing terpenes, polyisoprenes, ethanol, methane, and methanol.

10. The method for treating rubber waste according to claim 9, wherein the synthesis step is a step of synthesizing either isoprene or ethanol or both.

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