Method and apparatus for producing carbon-recoverable manganese alloy

Abstract

To provide a method and an apparatus for producing carbon-recovering type manganese-based alloys by which the reduction of CO2 discharge is made possible.SOLUTION: A method for producing a carbon-recovering type manganese-based alloy includes a step (A) of charging a manganese ore-derived raw material having a manganese oxidation degree of 1.0 to 1.1 and a carbonaceous material into an electric furnace to perform refining, and then performing slag / metal separation, and a step (B) of producing a synthetic fuel using carbon monoxide contained in a by-product gas generated from the electric furnace as a raw material.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for producing a manganese alloy with carbon recovery, in which carbon monoxide contained in a by-product gas generated in the production process of a manganese alloy is used as a raw material to produce a synthetic fuel and recover the carbon. [Background technology]

[0002] Manganese alloys, such as ferromanganese, are produced by heating manganese ore and a reducing agent such as coke in a blast furnace or electric furnace to reduce the manganese and iron in the ore. The blast furnace method uses coke as both the heat source and the reducing agent, while the electric furnace method basically uses electricity as the heat source and coke as the reducing agent.

[0003] Conventionally, technological developments in the production of manganese-based alloys have focused on how to produce them as efficiently as possible. For example, Patent Documents 1 and 2 disclose technologies in which a reducing agent such as a silicon-containing ferroalloy or metallic aluminum is added to further reduce and extract the manganese remaining in the slag. Furthermore, Patent Documents 3 to 6 disclose technologies in which, rather than directly adding manganese ore to a blast furnace or electric furnace, manganese ore is pre-reduced with carbon monoxide (CO) gas or coke generated in the blast furnace or electric furnace process and then added to the blast furnace or electric furnace. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-161079 [Patent Document 2] Japanese Patent Application Publication No. 59-222552 [Patent Document 3] Japanese Unexamined Patent Publication No. 63-195244 [Patent Document 4] Japanese Patent Application Publication No. 59-215458 [Patent Document 5] Special Publication No. 38-4456 [Patent Document 6] Special Publication No. 38-12811 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, various techniques have been developed to efficiently produce manganese-based alloys, but the by-product gases that are generated have only been used for the preliminary reduction of ores or as fuel for power generation, as described above.

[0006] However, Patent Documents 1 to 5 and other prior art documents related to the production of manganese-based alloys do not describe or suggest any technological development aimed at reducing CO2 emissions. Conventional technological developments related to the production of manganese-based alloys have indirectly reduced CO2 emissions to some extent by increasing efficiency, but no efforts have been made to recover carbon from the by-product gases generated from the perspective of reducing CO2 emissions.

[0007] We came to the conclusion that it was necessary to develop technology for manufacturing manganese-based alloys that were carbon neutral and had zero CO2 emissions in order to combat global warming.

[0008] The present invention has been made in consideration of the above problems, and aims to provide a carbon recovery type manganese alloy manufacturing method and manufacturing apparatus that enable a reduction in CO2 emissions in the production of manganese alloys. [Means for solving the problem]

[0009] The by-product gases generated in the production of manganese alloys using conventional electric furnace methods contain 45% to 65% carbon monoxide (CO), and as mentioned above, are used as fuel for the pre-reduction of manganese ore and for power generation. However, the use of these by-product gases does not result in the fixation or recovery of carbon, and instead results in the emission of carbon dioxide (CO2).

[0010] The present inventors came up with the idea of ​​recovering carbon by using CO contained in by-product gas as a raw material to produce synthetic fuel. However, although current by-product gases contain CO, the CO content is at most 65%, and a higher CO concentration is required to efficiently produce synthetic fuel. Therefore, the inventors conducted further research and, by considering the mechanism of CO generation in exhaust gas during the production of manganese-based alloys, discovered a method for producing exhaust gas (by-product gas) containing a high CO concentration of preferably 80% or more. Specifically, they discovered that when a manganese-based alloy is produced using a manganese ore-derived raw material with a manganese oxidation degree of 1.0 to 1.1, the exhaust gas contains a high concentration of CO, leading to the completion of the present invention.

[0011] (1) A method for producing a carbon-recovery manganese alloy, which is characterized by combining a step (A) of refining a manganese ore-derived raw material having a manganese oxidation degree of 1.0 to 1.1 and a carbonaceous material in an electric furnace, followed by slag-metal separation, and a step (B) of producing a synthetic fuel using carbon monoxide contained in the by-product gas generated from the electric furnace as a raw material.

[0012] (2) The method for producing a carbon-recovery type manganese alloy according to (1), wherein the manganese ore-derived raw material is obtained by reducing manganese ore with hydrogen or carbon monoxide, or with both hydrogen and carbon monoxide, to a manganese oxidation degree of 1.0 to 1.1.

[0013] (3) A method for producing a carbon-recovery type manganese alloy according to (1) or (2), characterized in that part or all of the carbon monoxide is carbon monoxide contained in a by-product gas generated from an electric furnace.

[0014] (4) The method for producing a carbon recovery type manganese alloy according to any one of (1) to (3), wherein a part or all of the carbonaceous material is green carbon.

[0015] (5) The method for producing a carbon-recovery type manganese alloy according to any one of (1) to (4), characterized in that granulated material containing the manganese ore-derived raw material and a carbonaceous material is charged into the electric furnace.

[0016] (6) A method for producing a manganese-based alloy with carbon recovery according to any one of (1) to (5), characterized in that it comprises a step (C) of introducing a reducing agent containing a silicon-containing ferroalloy or metallic aluminum, or both a silicon-containing ferroalloy and a reducing agent containing metallic aluminum, into the molten slag by-produced in the step (A) to reduce at least a portion of the manganese oxide contained in the molten slag, thereby producing a manganese-based ferroalloy.

[0017] (7) A carbon recovery type manganese alloy manufacturing apparatus, which is characterized by combining a means (A) for feeding manganese ore-derived raw material with a manganese oxidation degree of 1.0 to 1.1 and carbon material into an electric furnace to perform refining, and then separating the slag and metal, and a means (B) for producing synthetic fuel using carbon monoxide contained in the by-product gas generated from the electric furnace as a raw material.

[0018] (8) The carbon recovery type manganese alloy manufacturing apparatus according to (9), wherein the manganese ore-derived raw material is obtained by reducing manganese ore with hydrogen or carbon monoxide, or with both hydrogen and carbon monoxide, to a manganese oxidation degree of 1.0 to 1.1.

[0019] (9) The carbon recovery type manganese alloy manufacturing apparatus according to (7) or (8), wherein a part or all of the carbon monoxide is carbon monoxide contained in a by-product gas generated from an electric furnace.

[0020] (10) The carbon recovery type manganese alloy manufacturing apparatus according to any one of (7) to (9), wherein a part or all of the carbonaceous material is green carbon.

[0021] (11) The apparatus for producing a manganese alloy with carbon recovery according to any one of (7) to (10), characterized in that granulated material containing the manganese ore-derived raw material and a carbonaceous material is charged into the electric furnace.

[0022] (12) The apparatus for producing a manganese-based alloy with carbon recovery according to any one of (7) to (11), characterized by comprising a step (C) of introducing a reducing agent containing a silicon-containing ferroalloy or metallic aluminum, or both a silicon-containing ferroalloy and a reducing agent containing metallic aluminum, into the molten slag by-produced in the step (A) to reduce at least a portion of the manganese oxide contained in the molten slag, thereby producing a manganese-based ferroalloy. [Effects of the Invention]

[0023] The present invention has the advantage that the carbon monoxide (CO) concentration in the by-product gas in the production of manganese-based alloys can be increased, thereby enabling efficient production of synthetic fuels. It also has the advantage that carbon emitted in the production of manganese-based alloys can be recovered. [Brief explanation of the drawings]

[0024] [Figure 1] Temperature dependence of Gibbs free energy ΔG (chemical potential) of each reaction [Figure 2] Example of thermogravimetric analysis results of manganese ore (comilog) in 4% hydrogen / nitrogen mixed gas [Figure 3] One example of a production flow of a carbon recovery type manganese alloy according to an embodiment of the present invention [Figure 4] Another example of the manufacturing flow of a carbon recovery type manganese alloy according to an embodiment of the present invention [Figure 5] Example of a conventional manganese alloy manufacturing flow DETAILED DESCRIPTION OF THE INVENTION

[0025] In the conventional production of manganese-based alloys by electric furnace methods, coke is used as a carbonaceous material to reduce manganese and iron in manganese ore. The present inventors have found that the coke charged into an electric furnace can be used mainly for the following reactions.

[0026] MnO2 (manganese ore) + CO → MnO + CO2 (Equation 1) MnO + C (coke) → Mn + CO (Eq. 2) MnO2+ C → Mn + CO2 (Formula 1) + (Formula 2) (Formula 3) 1 / 2Fe2O3+ 3 / 4C → Fe + 3 / 4CO2 (Formula 4) C + CO2→ 2CO (Equation 5) The coke reduces manganese ore (containing iron oxide) to a manganese alloy (e.g., ferromanganese), converting it into carbon dioxide (CO2) and emitting it from the electric furnace. However, in reality, the coke is introduced for the next reaction, and the carbon dioxide (CO2) and the coke (C) undergo a solution-loss reaction (Boudouard reaction), resulting in the coke being consumed for purposes other than the reduction of the manganese ore. Therefore, while the by-product gas from the conventional electric furnace process for the production of manganese alloys is theoretically carbon dioxide (CO2), in reality, it also contains carbon monoxide (CO) generated by the solution-loss reaction. Therefore, the inventors came up with the idea that the concentration of carbon monoxide (CO) contained in the by-product gas is determined by equilibrium and kinetics, and is limited to a maximum of approximately 65%.

[0027] The present inventors further investigated the reduction reaction of manganese ore in detail and found that tetravalent manganese (equivalent to MnO2) can be reduced to divalent manganese (equivalent to MnO) using carbon monoxide (CO), but divalent manganese (equivalent to MnO) cannot be reduced to zerovalent manganese (metallic Mn) using carbon monoxide (CO); only carbon (C) can reduce it (Figure 1). Based on this, the present inventors arrived at the following invention.

[0028] Specifically, when manganese alloys (ferromanganese) are produced in an electric furnace using reduced manganese ore, in which the manganese ions in the manganese ore have been reduced in advance, preferably to divalent manganese (MnO), the carbonaceous material introduced into the electric furnace is reduced to metallic manganese (ferromanganese) according to the reaction in (Equation 2), while also generating carbon monoxide (CO). In other words, since the reaction in (Equation 1) does not occur in an electric furnace, the gas generated is primarily carbon monoxide (CO), which is generated by the reaction in (Equation 2). Therefore, carbon dioxide (CO2) is not generated as in conventional electric furnaces, and the solution loss reaction in (Equation 5) does not occur. In other words, the gas emitted from the electric furnace is mostly carbon monoxide (CO), with nearly no carbon dioxide (CO2).

[0029] By operating the electric furnace as described above, the carbon monoxide (CO) concentration in the by-product gas generated can be increased, and synthetic fuel can be produced efficiently using the by-product gas. Furthermore, efficient synthetic fuel production also means efficient carbon recovery. According to one embodiment, the carbon monoxide (CO) concentration in the by-product gas is 80% or more, 84% or more, 87% or more, or 90% or more. In practice, the concentration is 99% or less, or 98% or less.

[0030] Therefore, the method for producing a carbon-recovery manganese-based alloy of the present invention combines step (A) of refining a manganese ore-derived raw material having a manganese oxidation degree of 1.0 to 1.1 and a carbonaceous material in an electric furnace, followed by slag-metal separation, and step (B) of producing a synthetic fuel using carbon monoxide contained in a by-product gas generated from the electric furnace as a raw material.

[0031] In the present invention, the manganese ore-derived raw material may be prepared by any method as long as it has a manganese oxidation degree in the range of 1.0 to 1.1. For example, the manganese ore-derived raw material may be prepared by reducing manganese ore, and examples of the reducing agent include coal, coke, hydrocarbons (LNG, LPG, etc.), hydrogen, and carbon monoxide. Among these, the manganese ore-derived raw material is preferably prepared by reducing manganese ore with hydrogen or carbon monoxide, or with both hydrogen and carbon monoxide, to a manganese oxidation degree of 1.0 to 1.1. When the manganese ore-derived raw material is prepared by reduction with these materials, CO2 emissions can be reduced. From the viewpoint of reducing CO2 emissions, it is more preferable to prepare the manganese ore-derived raw material using hydrogen.

[0032] Furthermore, when the manganese ore-derived raw material is produced using carbon monoxide (CO), it is preferable that part or all of the carbon monoxide is carbon monoxide contained in the by-product gas generated from the electric furnace, thereby increasing energy efficiency.

[0033] Therefore, it is more preferable to include a step of producing the manganese ore-derived raw material from manganese ore.

[0034] Here, the manganese oxidation degree (Mn oxidation degree) will be explained. When expressed as the composition formula MnOx, the value of x is the manganese oxidation degree. For example, a manganese oxidation degree of x=2 is MnO2, and a manganese oxidation degree of x=1 is MnO. Therefore, the manganese oxidation degree of manganese ore or reduced manganese ore is determined by calculating x of MnOx from the total manganese amount (Mn%, JIS M8232 Manganese Ore - Manganese Determination Method) and the available oxygen value of manganese oxide (MnO2%, JIS M8233 Manganese Ore - Active Oxygen Determination Method).

[0035] The manganese oxidation degree of the manganese ore-derived raw material is 1.0 to 1.1. Ideally, a manganese oxidation degree of 1.0 is most preferable, but in reality, the effects of the present invention can be sufficiently obtained even with a manganese oxidation degree of 1.1 or less. If the manganese oxidation degree exceeds 1.1, the carbon monoxide (CO) content in the by-product gas becomes too low and the carbon dioxide (CO2) content becomes too high, resulting in inefficient production of synthetic fuel from the by-product gas. A more preferable range of the manganese oxidation degree is 1.0 to 1.05.

[0036] Regarding the hydrogen reduction of manganese ore to produce a manganese ore-derived raw material, any conditions containing hydrogen are acceptable, and more preferably, the proportion of hydrogen in the reducing agent is 50% or more, even more preferably 70% or more, even more preferably more than 70%, and even more preferably 90% or more. Most preferably, no reducing agent that generates CO2 is included, or the reducing agent contains only impurities.

[0037] In addition to the reducing agent, the reducing agent may contain nitrogen, water vapor, CO2, argon, helium, oxygen, nitrogen oxides, etc. The hydrogen content in the hydrogen reduction is sufficient as long as it can reduce the manganese ore to the desired oxidation level, but it may also be, for example, 1% or more and 10% or less, or 5% or less, or 4% or less.

[0038] The heating required to reduce manganese ore to produce a manganese ore-derived raw material may be any heating method capable of heating the manganese ore to a temperature at which the ore can be reduced. However, a heating method capable of reducing carbon dioxide (CO2) emissions is preferred. For example, electrical heating is preferred from the viewpoint of reducing carbon dioxide (CO2) emissions. Furthermore, heating by hydrogen combustion is preferred from the viewpoint of reducing carbon dioxide (CO2) emissions and being able to be performed simultaneously with hydrogen supply. The heating may be performed to a temperature at which the manganese ore can be reduced; for example, reduction can be achieved at a temperature of 750°C or higher and 1250°C or lower. The higher the temperature, the faster the reduction; however, at temperatures exceeding 1250°C, the manganese ore may solidify due to sintering or partial melting, making it difficult to handle. On the other hand, at temperatures below 750°C, reduction may be insufficient or take too long. A more preferred temperature is 800°C or higher and 1200°C or lower. In this case, the temperature may be higher than 1000°C, 1050°C or higher, or 1080°C or higher, and in this case, there is an effect that reduction can be carried out in a short time without causing partial melting.

[0039] Furthermore, iron oxide (e.g., Fe2O3) contained in small amounts in manganese ore is preferably reduced to metallic iron (Fe) when used as the manganese ore-derived raw material. This is because iron oxide can also be reduced by carbon monoxide (CO) to metallic iron, producing carbon dioxide (CO2), which slightly increases the proportion of carbon dioxide in the by-product gas. Furthermore, a solution loss reaction between carbon dioxide (CO2) and the carbonaceous material occurs in the electric furnace, reducing the utilization rate of the carbonaceous material. In other words, a small amount of carbonaceous material is required to compensate for the amount consumed in the reaction.

[0040] The manganese ore-derived raw material prepared by the above method is fed into an electric furnace together with carbonaceous material for refining, followed by slag and metal separation to produce a manganese-based alloy. The electric furnace can be a conventional submerged arc furnace or equivalent, heated primarily by electricity and used primarily with carbonaceous material to reduce the manganese ore-derived raw material to metallic manganese (manganese-based alloy). As refining progresses in the electric furnace, molten slag and molten manganese-based alloy are formed. Due to the difference in their specific gravities, the molten manganese-based alloy is deposited at the bottom of the furnace and the molten slag is deposited above it. Depending on the timing of the tapping and the height of the tap, the slag and metal are separated and discharged from the electric furnace. Manganese-based alloys produced using carbonaceous material in this way produce ferromanganese containing carbon, which may then be decarburized depending on the intended use.

[0041] According to one embodiment, the electric furnace is operated so that the slag produced contains approximately 30% by mass of manganese. A step of refining some or all of the slag by molten oxide electrolysis followed by slag-metal separation may be included. The molten oxide electrolysis involves melting reduced manganese ore, placing two electrodes (anode and cathode) in contact with the molten material, and applying a voltage sufficient to reduce divalent manganese to zerovalent manganese (metallic manganese), thereby producing molten metallic manganese (manganese-based alloy). The heat source for melting the reduced manganese ore can be electric heating, utilizing Joule heat generated by the current flowing between the electrodes, or a separate heat source. Manganese-based alloys produced in this way without using carbonaceous materials yield ferromanganese or metallic manganese with almost no carbon content.

[0042] Furthermore, if the process includes a step of producing a manganese-based ferroalloy by adding a reducing agent containing a silicon-containing ferroalloy or metallic aluminum, or both a silicon-containing ferroalloy and metallic aluminum, to the slag obtained in the electric furnace to reduce at least a portion of the manganese oxide contained in the molten slag, the manganese remaining in the slag can be recovered, thereby improving productivity. Manganese-based alloys produced from Mn-containing slag without using a carbonaceous material in this way can produce ferromanganese or metallic manganese that contains almost no carbon.

[0043] The carbonaceous material used in the electric furnace in step (A) may be conventional coke, but using green carbon in part or in whole will improve the carbon dioxide (CO2) reduction effect. Examples of green carbon include biocarbon (biologically derived carbonaceous materials such as charcoal and bamboo charcoal), coke made from waste plastics, fuel-derived carbonaceous materials obtained from hydrogen and carbon dioxide synthesized using renewable energy, and green coke synthesized using renewable energy. In particular, when biocarbon (biocoke) obtained by fixing carbon dioxide is used in an electric furnace and synthetic fuel is produced from by-product gas, the process not only does not emit carbon dioxide (carbon neutral) but also fixes carbon dioxide (carbon negative).

[0044] In addition, a part or all of the carbonaceous material may be granulated together with a manganese ore-derived raw material to form carbonaceous material-containing pellets, which are then charged into an electric furnace. By forming such carbonaceous material-containing pellets, the reduction reaction and gas release in the electric furnace may be improved, which may facilitate stable operation and improve the carbonaceous material consumption rate.

[0045] Furthermore, crushed scraps of manganese alloy products or mining powder of raw manganese ore may be contained in the carbonaceous composite pellets. The carbonaceous composite pellets described above are more effective when green carbon is used, and when the carbonaceous material used in the carbonaceous composite pellets is green carbon, the green carbon can act as a reducing agent more efficiently.

[0046] The granulation method for carbonaceous composite pellets can be a conventional method, such as a pellet method, a briquette method, an extrusion molding method, etc. Therefore, it is more preferable to include a step of granulating a manganese ore-derived raw material, a carbonaceous material, and optionally adding a binder, product crushed chips, etc., to produce carbonaceous composite pellets.

[0047] A slag former (slag conditioner) can be added to the electric furnace in step (A). Slag formers can control the viscosity, oxygen potential, basicity, and other properties of the slag. Examples of such slag formers include lime, slaked lime, Na2CO3, CaCl2, and MgCO2.

[0048] In step (B) of producing synthetic fuel using carbon monoxide contained in the by-product gas generated from the electric furnace as a raw material, any method may be used as long as it can produce synthetic fuel. Synthetic fuel in the present invention refers to hydrocarbons synthesized from carbon monoxide. Examples of synthetic methods include those using hydrogen (H2) and various catalysts. Examples include producing methane using a nickel (Ni)-based catalyst, producing methanol using a copper (Cu)-based catalyst (Cu / ZnO, Cu / ZrO2), producing dimethyl ether (DME) by dehydrating methanol, and producing gasoline or diesel fuel by Fischer-Tropsch (FT) synthesis. FT synthesis also uses catalysts, including Co, Fe, and Ru-based catalysts.

[0049] Any type of hydrogen (H2) can be used for the synthetic fuel, but from the perspective of reducing CO2 emissions, blue hydrogen or turquoise hydrogen is preferable to gray hydrogen, and green hydrogen is preferable to blue hydrogen or turquoise hydrogen. Other types of hydrogen that can be used include yellow hydrogen, brown hydrogen, and white hydrogen. Here, gray hydrogen is hydrogen produced from fossil fuels (for example, by reacting natural gas with steam to produce hydrogen (H2) and carbon dioxide (CO2)).

[0050] Like gray hydrogen, blue hydrogen is hydrogen produced from fossil fuels, but CO2 emissions are reduced to zero through the capture and underground storage of the carbon dioxide produced. Turquoise hydrogen is hydrogen (H2) produced by the thermal decomposition of methane (CH4). The carbon (C) contained in methane is fixed as solid carbon (C) in materials such as carbon nanotubes. The high-temperature reactor used to produce turquoise hydrogen uses renewable energy. Yellow hydrogen is produced by electrolyzing water (H2O) using nuclear power to produce hydrogen (H2) and oxygen (O2). This method produces zero CO2 emissions but generates nuclear waste. Brown hydrogen is hydrogen (H2) produced from coal. It is also gray hydrogen, but emits more CO2 than gray hydrogen. White hydrogen is hydrogen (H2) produced as a by-product in the production of other products (such as steelmaking). Therefore, production volume cannot be controlled. Green hydrogen is hydrogen (H2) synthesized using renewable energy by electrolyzing water (H2O) into hydrogen (H2) and oxygen (O2) with zero CO2 emissions.

[0051] It is more preferable to have a step of desulfurizing or dechlorinating the by-product gas, or both of these, prior to the step of producing the synthetic fuel.

[0052] The manganese-based alloy manufacturing apparatus that achieves the above-described method for manufacturing manganese-based alloys includes a means (A) for feeding a manganese ore-derived raw material having a manganese oxidation degree of 1.0 to 1.1 and a carbonaceous material into an electric furnace for refining, followed by slag / metal separation, and a means (B) for producing synthetic fuel using carbon monoxide contained in a by-product gas generated from the electric furnace as a raw material.

[0053] It is more preferable that the method further comprises means (C) for producing a manganese-based ferroalloy by adding a reducing agent containing a silicon-containing ferroalloy or metallic aluminum, or both a silicon-containing ferroalloy and a reducing agent containing metallic aluminum, to the molten slag by-produced in the means (A) to reduce at least a portion of the manganese oxide contained in the molten slag. It is more preferable that the apparatus further includes a means (D) for reducing manganese ore to produce a manganese ore-derived raw material having a manganese oxidation degree of 1.0 to 1.1, and a granulating means (E) for producing carbonaceous composite pellets containing the manganese ore-derived raw material and carbonaceous material. [Example]

[0054] Examples of the present invention are given below.

[0055] (Manufacturing raw materials derived from manganese ore) This example shows how manganese ores such as Gabonese manganese ore (Comilog) and South African manganese ore (Assoman) are heated and reduced with hydrogen to produce manganese ore-derived raw materials with a manganese oxidation degree of 1.0 to 1.1.

[0056] We apply industrial furnaces capable of heating and reducing manganese ore, such as fluidized-bed furnaces, shaft furnaces, and rotary kilns. Experimentally, manganese ore was heated in a tubular furnace and reduced with hydrogen gas to produce reduced manganese ore. As an example, Gabonese manganese ore (containing MnO) was placed in an alumina boat and charged into a tubular furnace. It was then heated at 1100°C for 5 hours under a 4% hydrogen / nitrogen gas flow, yielding a manganese ore-derived raw material. The manganese oxidation degree of the resulting manganese ore-derived raw material was measured and calculated according to the above-mentioned measurement methods (JIS M8232 and JIS M8233), resulting in a manganese oxidation degree of 1.05. Similar results were obtained using South African manganese ore (Assoman). A similar test using 10% carbon monoxide / nitrogen gas instead of hydrogen gas also yielded a manganese ore-derived raw material. The manganese oxidation degree was 1.05. Furthermore, when manganese ore is mixed with 8% coke by mass and subjected to a similar test using nitrogen gas, a manganese ore-derived raw material is obtained. The manganese oxidation degree is 1.0.

[0057] Furthermore, when thermogravimetric analysis was performed on the manganese ore while flowing a 4% hydrogen / nitrogen mixed gas, the mass loss due to manganese reduction was confirmed, as shown in Figure 2. It was found that hydrogen reduction was possible when the ore was heated to 750°C or higher. Increasing the hydrogen reduction temperature facilitates the reduction of manganese ore, shortening the reduction treatment time, for example. However, if the hydrogen reduction temperature is too high, the reduced manganese ore may stick together (sintering or fusion solidification) and solidify, making it difficult to handle. For these reasons, the hydrogen reduction temperature is preferably 1250°C or lower, and more preferably 1200°C or lower. As mentioned above, a hydrogen concentration of 4% is sufficient for hydrogen reduction, but it may be increased to 4% or higher for more efficient reduction. Conversely, hydrogen concentrations of around 1% are sufficient for reduction, but because the hydrogen-containing gas is supplied in accordance with the amount of manganese ore to be processed, a concentration of less than 1% may require a large amount of hydrogen-containing gas, which may be impractical.

[0058] A more industrial example of manganese ore-derived raw material production is an experiment on hydrogen reduction of manganese ore using an externally heated rotary kiln. A 4% hydrogen / nitrogen mixed gas was introduced into the test kiln, and the manganese ore was heated and hydrogen-reduced in the test kiln to obtain a manganese ore-derived raw material. For example, a manganese ore-derived raw material with a manganese oxidation degree of 1.1 was obtained by treating the manganese ore at 1100°C for 3 hours. The manganese oxidation degree of the manganese ore-derived raw material can be varied by adjusting the amount of hydrogen-containing gas introduced, the heating temperature, and the heating time relative to the amount of manganese ore. A higher manganese oxidation degree of the manganese ore-derived raw material shortens the hydrogen reduction process and reduces the amount of hydrogen required, but reduces the CO2 reduction effect. Conversely, as the manganese oxidation degree of the reduced manganese ore decreases to 1.0 or closer to 1.0, the CO2 reduction effect increases and the CO2 concentration in the by-product gas increases.

[0059] Another example of a more industrial production of manganese ore-derived raw material involves an experiment in which manganese ore and coke are added and reduced in an internal combustion rotary kiln. The fuel / air ratio of the internal combustion burner is set to 1.0 or less (0.96), and 7% by mass of coke is added. The manganese ore-derived raw material is obtained by treating the material at 1100°C for 4 hours. The manganese oxidation degree is 1.08. The same results are obtained when the coke is replaced with bio-coke. The same results are also obtained when the fuel for the internal combustion burner is replaced with biofuel.

[0060] (Manufacturing manganese alloys from manganese ore-derived raw materials) Next, an experiment will be described in which a manganese ore-derived raw material (manganese oxidation degree = 1.1) is reduced with a carbonaceous material to produce a manganese-based alloy. In industrial practice, a submerged arc furnace or an electric furnace with equivalent functionality is used to reduce a manganese ore-derived raw material with a carbonaceous material, but here, the following experiment will be described.

[0061] The manganese-based alloy is obtained by refining the manganese ore-derived raw material and coke as a carbonaceous material in a 100 kVA Giraud furnace (single-phase arc furnace), then tapping to separate and remove the molten manganese alloy (ferromanganese) from the slag. Because the Giraud furnace is an open furnace, the amount of carbon monoxide (CO) (carbon dioxide (CO2)) generated cannot be measured. However, the manganese-based alloy can be produced by reducing the manganese ore-derived raw material with a carbonaceous material. Furthermore, the oxygen content (manganese oxidation degree) of the manganese ore-derived raw material used as the raw material is lower than that of manganese ore, so less carbonaceous material is required. The resulting manganese-based alloy (ferromanganese) satisfies JIS G 2301.

[0062] In addition, a mixture of manganese ore-derived raw material (manganese oxidation degree = 1.05) and coke as carbonaceous material was placed in a refractory container, and electrically heated to 1490°C in a vertical tubular furnace while circulating an inert carrier gas (nitrogen N2 or argon Ar), and the concentration of carbon monoxide (CO) generated was measured. A similar experiment was performed using manganese ore for comparison, and it was found that the use of the manganese ore-derived raw material resulted in a higher carbon monoxide (CO) concentration and a lower carbon dioxide (CO2) concentration.

[0063] (Synthesis of synthetic fuel using carbon monoxide contained in by-product gas) The synthesis of synthetic fuel using carbon monoxide (CO) and hydrogen (H2) contained in by-product gas as raw materials has been proven, for example, in a device that synthesizes synthetic fuel from synthetic gas (H2 + CO) in the GTL (Gas to Liquids) process, so it is clear that synthetic fuel can also be produced from the by-product gas of the present invention. Also, CO + 2H2 → 1 / nC n H 2n + H2O, it can be seen that the higher the concentration (partial pressure) of carbon monoxide (CO), the easier it is to produce synthetic fuel.

[0064] Experimentally, the carbon monoxide (CO) generated in the above experiment and hydrogen (H2) are added, and the mixture is passed through a reaction tube coated with a catalyst such as a Ni-based catalyst (methane production), a Cu-based catalyst (methanol production), or a Co-based catalyst (FT synthesis). The products are then analyzed using a gas chromatograph or similar device, allowing the production of synthetic fuel to be confirmed.

[0065] Based on the above, one example of an embodiment of the present invention is shown in Figure 3. High-carbon ferromanganese is produced by reducing a manganese ore-derived raw material with a manganese oxidation degree of 1.0 to 1.1 and a carbonaceous material in an electric furnace. During this process, slag and a by-product gas, CO, are generated, and the by-product gas, CO, is passed through a separately prepared synthesis device together with H2 to produce synthetic fuel.

[0066] Another example of the embodiment is shown in Figure 4. Manganese ore is passed through a gas reduction furnace with H2 and / or CO2 to produce a manganese ore-derived raw material, and then the manganese ore-derived raw material and carbonaceous material are subjected to a reduction reaction in an electric furnace to produce high-carbon ferromanganese. During this process, slag and CO2 by-product gas are generated, and the CO2 by-product gas is passed through a separately prepared synthesis device to produce synthetic fuel. [Industrial Applicability]

[0067] According to the present invention, it is possible to realize the production of carbon recovery type manganese alloys, which can achieve a significant CO2 reduction effect, contribute to the suppression of global warming, and meet the demands for carbon neutrality and zero CO2 emissions.

Claims

1. A step (A) of refining a manganese ore-derived raw material having a manganese oxidation degree of 1.0 to 1.1 and a carbonaceous material in an electric furnace, followed by separating the slag and metal; A method for producing a carbon-recovery type manganese alloy, comprising the step (B) of producing a synthetic fuel using carbon monoxide contained in a by-product gas generated from the electric furnace as a raw material.

2. 2. The method for producing a carbon-recovery type manganese alloy according to claim 1, wherein the manganese ore-derived raw material is obtained by reducing manganese ore with hydrogen or carbon monoxide, or with both hydrogen and carbon monoxide, to a manganese oxidation degree of 1.0 to 1.

1.

3. 3. The method for producing a carbon-recovery type manganese alloy according to claim 1, wherein a part or all of the carbon monoxide is carbon monoxide contained in a by-product gas generated from an electric furnace.

4. 4. The method for producing a carbon recovery type manganese alloy according to claim 1, wherein a part or all of the carbon material is green carbon.

5. 5. The method for producing a carbon-recovery type manganese alloy according to claim 1, wherein granulated material containing the manganese ore-derived raw material and a carbonaceous material is charged into the electric furnace.

6. 6. The method for producing a manganese-based alloy with carbon recovery according to any one of claims 1 to 5, further comprising: step (C) of introducing a reducing agent containing a silicon-containing ferroalloy or metallic aluminum, or both a silicon-containing ferroalloy and a reducing agent containing metallic aluminum, into the molten slag by-produced in step (A) to reduce at least a portion of the manganese oxide contained in the molten slag, thereby producing a manganese-based ferroalloy.

7. A means (A) for refining a manganese ore-derived raw material having a manganese oxidation degree of 1.0 to 1.1 and a carbonaceous material in an electric furnace, followed by separating the slag and metal; A carbon recovery type manganese alloy manufacturing apparatus comprising: means (B) for producing synthetic fuel using carbon monoxide contained in the by-product gas generated from the electric furnace as a raw material.

8. 10. The carbon recovery type manganese alloy manufacturing apparatus according to claim 9, wherein the manganese ore-derived raw material is obtained by reducing manganese ore with hydrogen or carbon monoxide, or with both hydrogen and carbon monoxide, to a manganese oxidation degree of 1.0 to 1.

1.

9. 9. The carbon recovery type manganese alloy manufacturing apparatus according to claim 7, wherein a part or all of the carbon monoxide is carbon monoxide contained in a by-product gas generated from an electric furnace.

10. 10. The carbon recovery type manganese alloy manufacturing apparatus according to claim 7, wherein a part or all of the carbonaceous material is green carbon.

11. 11. The apparatus for producing a manganese alloy with carbon recovery according to claim 7, wherein granulated material containing the manganese ore-derived raw material and a carbonaceous material is charged into the electric furnace.

12. 12. The apparatus for producing a manganese-based alloy with carbon recovery according to any one of claims 7 to 11, further comprising: means (C) for producing a manganese-based ferroalloy by adding a reducing agent containing a silicon-containing ferroalloy or metallic aluminum, or both a silicon-containing ferroalloy and a reducing agent containing metallic aluminum, to the molten slag by-produced in means (A) to reduce at least a portion of the manganese oxide contained in the molten slag.

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