TWI900993B - Iron-based mixed powder and oxygen reactant - Google Patents

Abstract

The present invention provides an iron-based mixed powder and an oxygen reactant that are easily manufactured, highly reactive with oxygen, and capable of suppressing hydrogen generation. The iron-based mixed powder comprises an iron-based powder having an oxygen/iron atomic ratio (O/Fe) of 0.800 or less, and a sulfur-containing powder having a sulfur content of 10.000% to 100.000% by mass. The sulfur-containing powder is present in an amount of 0.020% to 5.000% by mass relative to the combined content of the iron-based powder and the sulfur-containing powder.

Description

Iron-based mixed powder and oxygen reactant

The present invention relates to an iron-based mixed powder and an oxygen reactant.

Oxygen-reacting agents that utilize the reaction between iron-based powder and oxygen are used, for example, as deoxidizers and pyrogenators. Deoxidizers, when sealed together with stored items such as food and pharmaceuticals, create a low-oxygen environment within the container. This helps prevent degradation of stored items due to oxidation and the growth of aerobic mold. For example, pyrogenators are widely used in disposable pocket warmers. To further promote the reaction with oxygen, these oxygen-reacting agents are prepared by adding water, activated carbon, sodium chloride, or other substances to the iron-based powder. Furthermore, in addition to adjusting the reaction rate and thus the calorific value, additives are sometimes added to the oxygen reactant to treat gaseous by-products such as hydrogen.

Deoxidizers and exothermic agents are often sealed in airtight exterior materials immediately after manufacture. However, if oxygen remains within the exterior material, it will cause iron oxidation. This oxidation causes the water added to the deoxidizer and exothermic agent to decompose, generating hydrogen. If hydrogen gas is generated in large quantities, the exterior material will expand and potentially crack. Therefore, there is a desire to suppress hydrogen gas generation.

Patent Document 1 discloses a stoker. The oxidant used in the stoker is sulfur-treated iron powder. Specifically, the oxidant can be produced by heating sulfur powder and iron powder; heating iron powder coated with a sulfur solution, or iron powder impregnated with a sulfur solution and then dried to form a coating; or heating iron powder in a solution containing sulfur dissolved in a solvent. Patent Document 1 discloses that the use of sulfur-treated iron powder reduces gas generation.

Patent Document 2 relates to a raw iron powder for a slow-heating composition and its production method. The raw iron powder is mixed with a reaction aid, water, and a water-retaining agent to form a composition that slowly heats in the atmosphere. The raw iron powder is prepared by adding 1 gram of iron powder to 100 ml of water, stirring the mixture, and mixing the resulting supernatant to a pH of 8 to 10. Thiosulfate powder is then added to the mixture so that the sulfur content reaches 0.001% to 0.2% by weight. Patent Document 2 discloses that the use of this raw iron powder eliminates the need for adding large amounts of substances that could adversely affect the heat generation properties of the slow-heating composition and effectively suppresses hydrogen generation during storage. [Prior Art Document] [Patent Document]

Patent Document 1: Japanese Patent Publication No. 58-32762 Patent Document 2: Japanese Patent Publication No. 8-183951

(Invent the problem you want to solve)

However, the oxidant disclosed in Patent Document 1 must be heated in order to be treated with sulfur, which complicates the production process. Furthermore, it is expected that other sulfur-containing powders other than the thiosulfate powder disclosed in Patent Document 2 can be effectively utilized.

This invention was developed in light of these practical circumstances. Its purpose is to provide an iron-based mixed powder and oxygen reactant that are easily manufactured, highly reactive with oxygen, and capable of suppressing hydrogen generation. (Technical Solution)

To achieve the above objectives, the iron-based mixed powder and oxygen reactant of the present invention are as follows.

[1] An iron-based mixed powder comprising: an iron-based powder having an oxygen to iron atomic ratio (O/Fe) of 0.800 or less, and a sulfur-containing powder having a sulfur content of 10.000 mass % or more and 100.000 mass % or less; wherein the content of the sulfur-containing powder is 0.020 mass % or more and 5.000 mass % or less relative to the total content of the iron-based powder and the sulfur-containing powder.

[2] The iron-based mixed powder as described in [1] above, wherein the sulfur-containing powder contains manganese sulfide powder.

[3] The iron-based mixed powder as described in [1] or [2] above, wherein the volume-based median particle size is greater than or equal to 70 μm and less than or equal to 100 μm.

[4] An oxygen reactant comprising an iron-based mixed powder comprising: an iron-based powder having an oxygen to iron atomic ratio (O/Fe) of 0.800 or less, and a sulfur-containing powder having a sulfur content of 10.000 mass % or more and 100.000 mass % or less; wherein the sulfur-containing powder content is 0.020 mass % or more and 5.000 mass % or less relative to the total of the iron-based powder content and the sulfur-containing powder content.

[5] The oxygen reactant as described in [4] above, wherein the sulfur-containing powder contains manganese sulfide powder.

[6] The oxygen reactant as described in [4] or [5] above, wherein the volume-based median particle size of the iron-based mixed powder is greater than or equal to 70 μm and less than or equal to 100 μm. (Compared to the efficacy of the prior art)

The present invention can provide an iron-based mixed powder and an oxygen reactant that can be easily manufactured, has high reactivity with oxygen, and can suppress hydrogen generation.

The following describes the iron-based mixed powder and oxygen reactant used in embodiments of the present invention. Hereinafter, "iron-based powder" refers to a powder containing 50,000% or more of Fe. "Iron-based alloy powder" refers to an alloy powder containing 50,000% or more of Fe. "Iron powder" refers to a powder composed of Fe and unavoidable impurities, generally referred to as "pure iron powder" in the art.

The iron-based mixed powder of this embodiment is composed of an iron-based powder having an oxygen to iron atomic ratio (O/Fe) of 0.800 or less, and a sulfur-containing powder having a sulfur content of 10.000% to 100.000% by mass. The sulfur-containing powder content of this embodiment is 0.020% to 5.000% by mass, relative to the total of the iron-based powder and the sulfur-containing powder.

The oxygen reactant of this embodiment contains the above-mentioned iron-based mixed powder.

The iron-based mixed powder of this embodiment is highly reactive with oxygen and can suppress hydrogen generation, so it can be used as an oxygen reactant.

The iron-based mixed powder and oxygen reactant of this embodiment are described in detail below.

The iron-based mixed powder of this embodiment is a mixture of iron-based powder and sulfur-containing powder. The iron-based mixed powder is formed by iron-based powder and sulfur-containing powder.

The iron-based powder may be, for example, iron powder or iron-based alloy powder. When the iron-based powder is an iron-based alloy powder, in addition to Fe, it may further contain elements such as C, S, O, N, Si, Na, Mg, and Ca. When the iron-based powder is iron powder, it may also contain unavoidable impurities such as C, S, O, N, Si, Na, Mg, and Ca.

If iron is oxidized, its reactivity with oxygen decreases. Therefore, it is best to use unoxidized iron-based powder as much as possible. Specifically, to ensure the amount of reactivity with oxygen, the atomic ratio of oxygen to iron in the above-mentioned iron-based powder (hereinafter also referred to as "O/Fe") is 0.800 or less, preferably 0.700 or less, more preferably 0.600 or less, and particularly preferably 0.250 or less. In addition, there is no lower limit for O/Fe. O/Fe can be 0 or 0.000. However, considering industrial productivity, O/Fe is preferably 0.030 or more, and more preferably 0.150 or more.

The O/Fe ratio of the iron-based powder was measured using X-ray diffraction. Specifically, the measurement was performed using the method described in the Examples.

There is no particular limitation on the method for producing the above-mentioned iron-based powder, and it can be produced according to conventional methods. For example, the above-mentioned iron-based powder can be produced by methods such as an atomization method or a reduction method. The atomization method is a method of spraying water or gas toward the molten metal to pulverize it and then cool it to solidify. For example, either the water atomization method or the gas atomization method can be adopted. The reduction method is a method of reducing the iron oxide (rust scale) or iron ore powder produced on the surface of the steel plate when the steel is hot-rolled. That is, the above-mentioned iron-based powder can be an atomized iron-based powder or a reduced iron-based powder. The above-mentioned iron-based powder can be a water-atomized iron-based powder or a gas-atomized iron-based powder.

Furthermore, the powder may be subjected to either pulverization or classification or both to adjust the particle size. The pulverization and classification methods are not particularly limited and may be performed according to conventional methods.

To remove oxygen from the powder, the iron-based powder can be heat-treated (deoxidized) at a maximum temperature of 750°C or higher using a reducing agent to reduce the O/Fe ratio to 0.800 or less. Examples of the reducing agent include carbon such as coke, coal, or graphite, or hydrogen. The reducing agent can be added or mixed into the powder.

The sulfur-containing powder of this embodiment preferably contains either or both of elemental sulfur and a sulfur compound. The sulfur-containing powder may be composed of elemental sulfur or a sulfur compound. Specifically, the sulfur-containing powder preferably contains either or both of elemental sulfur and a sulfur compound. Furthermore, the sulfur contained in the sulfur-containing powder may be derived solely from either or both of elemental sulfur and a sulfur compound. In the following description, the term "sulfur powder" refers to elemental sulfur powder.

The sulfur compound may be, for example, a sulfide. Examples of the sulfide include manganese sulfide, calcium sulfide, sodium sulfide, and nickel sulfide. Specifically, the sulfur-containing powder may contain, for example, any one of manganese sulfide powder, calcium sulfide powder, sodium sulfide powder, and nickel sulfide powder, or any one of manganese sulfide powder, calcium sulfide powder, sodium sulfide powder, and nickel sulfide powder. For example, when using deliquescent sulfur compounds such as thiosulfate, they absorb moisture from the air, causing moisture to be supplied to the surrounding iron particles after mixing, potentially causing the iron-based powder to rust before use. From the perspective of preventing property degradation due to rusting, the sulfur-containing powder preferably contains either or both of sulfide and elemental sulfur, with either or both of sulfide powder and sulfur powder being particularly preferred. Among sulfides, manganese sulfide powder has a higher specific gravity than sulfur powder and is closer to that of iron-based powders, resulting in better miscibility with iron-based powders. Furthermore, manganese sulfide is less flammable than calcium sulfide, resulting in better storage. Therefore, the sulfur-containing powder preferably contains manganese sulfide, and more preferably, manganese sulfide powder.

Furthermore, the sulfur-containing powder may also contain, for example, additives. The additives may or may not contain sulfur. Examples of the additives include silicon dioxide and carbon. Specifically, the sulfur-containing powder may contain silicon dioxide powder or carbonaceous powder. Silica powder is an inert powder that does not participate in the reaction between iron and oxygen. It may be added to more evenly mix elemental sulfur and sulfur compounds with the iron-based powder. Carbonaceous powder may be added because it further promotes the reaction between iron and oxygen. Examples of the carbonaceous powder include activated carbon powder, coke powder, carbon black powder, acetylene black powder, and graphite powder.

The sulfur content of the sulfur-containing powder is 10.000 mass% or more and 100.000 mass% or less. A sulfur content of 10.000 mass% or more in the sulfur-containing powder increases the proportion of sulfur contacting the surface of the iron-based powder, thereby enhancing the reactivity between iron and oxygen. Furthermore, this content can suppress the generation of hydrogen. Therefore, the sulfur content of the sulfur-containing powder is set to 10.000 mass% or more, preferably 43.000 mass% or more, and more preferably 80.000 mass% or more. Meanwhile, the upper limit of the sulfur content of the sulfur-containing powder is not particularly limited and can be 100.000 mass%. However, from the perspective of adding additives, it can be set to, for example, 99.900 mass% or less.

In the iron-based mixed powder of this embodiment, the content of the sulfur-containing powder is 0.020 mass% or more and 5.000 mass% or less, relative to the total content of the iron-based powder and the sulfur-containing powder. In the following description, the content of the sulfur-containing powder relative to the total content of the iron-based powder and the sulfur-containing powder will be referred to as simply "the sulfur-containing powder content."

If the sulfur-containing powder content is 0.050 mass% or greater, reactivity with oxygen is enhanced and hydrogen is suppressed. Therefore, the sulfur-containing powder content is 0.050 mass% or greater, preferably 0.200 mass% or greater, more preferably 0.600 mass% or greater, and even more preferably 1.100 mass% or greater.

If the sulfur-containing powder content is 5.000 mass% or less, the water on the surface of the iron-based powder can be prevented from becoming excessively acidic, thereby suppressing the generation of hydrogen gas. Furthermore, while some hydrogen reacts with sulfur to form hydrogen sulfide, this reaction can suppress excessive generation of hydrogen sulfide gas, thereby suppressing the rotten egg odor caused by hydrogen sulfide gas. Therefore, the sulfur-containing powder content is set to 5.000 mass% or less, preferably 3.000 mass% or less.

The iron-based mixed powder of this embodiment is preferably prepared by uniformly mixing the iron-based powder and the sulfur-containing powder. During the production of the iron-based mixed powder, the iron-based powder and the sulfur-containing powder can be mixed using a powder mixing device such as a V-type mixer, a double-cone mixer, or a conical mixer.

The volume-based median particle size of the iron-based mixed powder (the median particle size calculated from the volume-based particle size distribution, so-called " _D50 ") is not particularly limited as long as it does not pose a problem in handling. However, to further enhance reactivity with oxygen, the volume-based median particle size of the iron-based mixed powder is preferably 1000 μm or less, more preferably 400 μm or less, even more preferably 200 μm or less, and particularly preferably 100 μm or less. Taking into account ease of handling and reactivity with oxygen, the volume-based median particle size of the iron-based mixed powder is preferably 5 μm or greater, and more preferably 70 μm or greater.

The volume-based median particle size of the iron-based mixed powder may be a value measured using a laser diffraction particle size distribution analyzer.

The volume-based median particle size of the iron-based mixed powder is specifically measured as follows. First, the powder to be measured is placed in ethanol and dispersed using ultrasonic vibration for at least 30 seconds. The volume-based particle size distribution is then measured using a laser diffraction particle size analyzer (LA-950V2, manufactured by Horiba, Ltd.) employing the laser diffraction/scattering method. The cumulative particle size distribution is calculated from the volume-based particle size distribution obtained, and the median particle size is determined.

The oxygen reactant of this embodiment contains the iron-based mixed powder of this embodiment. The oxygen reactant of this embodiment can use the above-mentioned iron-based mixed powder, and it does not exclude that it also contains other components in addition to the above-mentioned iron-based mixed powder.

Examples of other components include activated carbon and salt water.

The following example illustrates the reaction mechanism when adding salt water to the iron-based mixed powder. When the iron-based powder and the sulfur compound are mixed and salt water is added, the sulfur compound dissolves, resulting in fine sulfur particles at the boundaries between the iron particles contained in the iron-based powder and the sulfur compound particles. This fine sulfur particle then interacts with chloride ions from the salt water, causing the iron at these boundaries to dissolve.

The pores created on the surface of the iron particles due to the dissolution cause the hydrolysis of iron ions, which lowers the pH and potential of the aqueous solution. This promotes the dissolution of iron and allows for pore etching.

Furthermore, the sulfur in the fine sulfur powder produced on the surface of the iron particles reacts with the hydrogen produced during the hydrolysis process and is converted into hydrogen sulfide. This is believed to suppress the generation of hydrogen gas throughout the entire system.

Furthermore, hydrogen sulfide is more soluble in water than hydrogen. Therefore, the hydrogen generated during the hydrolysis process is converted into hydrogen sulfide and dissolved in water. Therefore, it is believed that this can suppress the generation of hydrogen sulfide gas.

The same behavior as the above-mentioned sulfur compounds can also be judged when elemental sulfur is mixed with iron-based powder.

The oxygen reactant of this embodiment can also be sealed in a bag. Examples of such bags include: a ventilated bag made of a laminated nonwoven fabric and open-pore polyethylene, or a ventilated bag made of a laminated paper and open-pore polyethylene. [Example]

The iron-based mixed powder of this embodiment is described below based on the examples.

The iron-based mixed powder of the embodiment is manufactured according to the following sequence.

Iron powder is obtained by reducing iron ore with coke at 800-1000°C and adjusting the O/Fe ratio. The O/Fe ratio is calculated by measuring the content of Fe alone, Fe-O compounds, and other compounds using an X-ray diffraction device (SmartLab, manufactured by Rigaku Corporation).

For Comparative Examples 2-15 and Examples 1-6, the sulfur-containing powder used was a mixture of sulfur powder (SSE02PB, manufactured by High-Jun Chemical Research Institute Co., Ltd.) and silicon dioxide powder (SIO09PB, manufactured by High-Jun Chemical Research Institute Co., Ltd.) with an adjusted sulfur content. For Comparative Examples 16-21 and Examples 7-8, the sulfur-containing powder used was manganese sulfide powder (MNI09PB, manufactured by High-Jun Chemical Research Institute Co., Ltd.). For Comparative Examples 22-27 and Examples 9-10, the sulfur-containing powder used was calcium sulfide powder (CA105PB, manufactured by High-Jun Chemical Research Institute Co., Ltd.).

The iron powder and the sulfur-containing powder were then mixed to obtain the iron-based mixed powders of the Examples and Comparative Examples. Comparative Example 1 did not include the addition of sulfur-containing powder. Table 1 shows the O/Fe ratio of the iron powder, the type of sulfur-containing powder, the sulfur content (mass %) of the sulfur-containing powder, the sulfur content (mass %) of the sulfur-containing powder, and the median particle size ( _D50 ) of the iron-based mixed powder measured using the above method. Underlined values in Table 1 indicate values outside the range of this embodiment.

[Table 1] Table 1 No. Iron-based mixed powder Reviews Iron-based powder Sulfur powder Sulfur powder content (mass %) D ₅₀ (μm) Oxygen reaction capacity (mL/g) Hydrogen concentration (volume %) Hydrogen sulfide gas concentration (ppm) O/Fe (-) Kind Sulfur content (mass%) Comparative example 1 0.150 - - - 420 50 12.3 0.0 Comparative example 2 0.820 Mixed powder of sulfur powder and silicon dioxide powder 9.852 0.016 412 53 11.9 0.0 Comparative example 3 0.880 9.924 5.082 475 56 4.7 0.3 Comparative example 4 0.830 8.451 0.021 495 62 11.2 0.0 Comparative example 5 0.920 9.211 4.988 427 64 1.8 0.2 Comparative example 6 0.980 10.128 0.012 935 67 10.2 0.0 Comparative example 7 0.830 10.043 5.118 720 69 4.5 0.3 Comparative example 8 0.860 10.655 0.022 447 72 9.5 0.0 Comparative example 9 0.820 10.552 4.885 413 75 1.6 0.2 Comparative example 10 0.050 9.725 0.008 955 66 8.5 0.0 Comparative example 11 0.120 9.559 5.343 780 69 2.5 0.3 Comparative example 12 0.780 9.324 0.032 500 79 8.8 0.1 Comparative example 13 0.550 9.749 4.789 478 83 1.8 0.2 Comparative example 14 0.230 10.956 0.018 465 89 3.2 0.0 Comparative example 15 0.110 12.535 5.043 420 92 2.3 0.3 Example 1 0.750 13.536 0.028 415 108 1.9 0.1 Example 2 0.520 11.542 4.752 407 104 1.8 0.2 Example 3 0.230 90.850 0.035 382 115 1.4 0.0 Example 4 0.110 99.842 0.025 212 118 1.2 0.0 Example 5 0.221 85.582 0.053 78 130 0.7 0.0 Example 6 0.139 88.254 0.045 92 128 0.5 0.0 Comparative example 16 0.815 Manganese sulfide powder 36.885 0.015 75 85 5.2 0.0 Comparative example 17 0.807 5.232 80 88 3.0 0.3 Comparative example 18 0.852 0.026 82 92 4.5 0.0 Comparative example 19 0.833 4.779 125 91 2.2 0.2 Comparative example 20 0.351 0.002 92 82 5.2 0.0 Comparative example 21 0.059 5.144 95 93 2.8 0.3 Example 7 0.122 0.029 80 125 0.8 0.0 Example 8 0.083 4.984 75 132 0.6 0.2 Comparative example 22 0.801 Calcium sulfide powder 44.446 0.017 88 87 4.5 0.0 Comparative example 23 0.813 5.086 98 86 4.8 0.3 Comparative example 24 0.835 0.028 95 93 2.8 0.0 Comparative example 25 0.821 4.965 90 90 3.0 0.2 Comparative example 26 0.246 0.018 86 92 3.5 0.0 Comparative example 27 0.050 5.068 90 94 3.3 0.3 Example 9 0.108 0.023 85 151 0.2 0.0 Example 10 0.085 4.921 90 165 0.1 0.2

The reactivity of the iron-based mixed powders of the Examples and Comparative Examples with oxygen, the amount of hydrogen generated, and the amount of hydrogen sulfide gas generated were evaluated in the following manner.

Reactivity with oxygen was evaluated as follows. First, 0.006 g of sodium chloride powder (NAH07PB, manufactured by Kojun Chemical Research Institute) was mixed with 1.50 g of an iron-based mixed powder. A mixture of 0.95 g of Isolite CG (No. 1, manufactured by Isolite Industries, Ltd.), a calcined diatomaceous earth product, and 0.85 g of water was added to the resulting powder. The mixture was then filled into a vented packaging bag (45 mm long x 40 mm wide) to prepare the sample for evaluation in the Examples or Comparative Examples. The vented packaging bag was a laminated material composed of nonwoven fabric and open-pore polyethylene.

Each sample was then sealed with 3000 mL of air in a gas barrier bag made of a five-layer laminated material consisting of nylon/polyethylene/aluminum foil/polyethylene/polyethylene. The sealed bags of each sample were left at 25°C for 72 hours. The oxygen concentration of the gas in the bag was then measured using a gas chromatograph (GC3210D manufactured by GL Sciences). The oxygen concentration in the bag was then subtracted from the oxygen concentration in the air to determine the oxygen reduction in the bag. The oxygen reaction amount (ml/g) per 1g of the iron-based mixed powder was then calculated based on this reduction.

Specifically, the "oxygen reactivity" in this embodiment refers to the volume (ml) of oxygen removed from 3000 mL of atmospheric pressure air at 25°C per 1 gram of the iron-based mixed powder over a 72-hour period. A higher oxygen reactivity indicates a higher reactivity with oxygen. Specifically, when the iron-based mixed powder is used in an oxygen reactant, it exhibits superior total calorific value, heating temperature, heating time, and other characteristics (excellent heating characteristics).

The amount of hydrogen gas and hydrogen sulfide gas generated was evaluated as follows. First, 0.06 g of sodium chloride powder (NAH07PB, manufactured by Kojun Chemical Research Institute Co., Ltd.) was mixed with 15.00 g of an iron-based mixed powder. To the resulting powder was added a mixture of 7.89 g of Isolite CG (No. 1, manufactured by Isolite Industries, Ltd.), a calcined diatomaceous earth product, and 7.11 g of water. The mixture was then filled into a vented packaging bag (80 mm long x 80 mm wide) to prepare the sample for evaluation in the Examples and Comparative Examples. The vented packaging bag was a laminated material composed of nonwoven fabric and open-pore polyethylene.

Each sample was then sealed with 25 mL of air in a gas-barrier bag made of a five-layer laminate consisting of nylon/polyethylene/aluminum foil/polyethylene/polyethylene. The sealed bags were then incubated at 55°C for 72 hours. The hydrogen concentration (volume %) within the bag was then measured using a gas chromatograph (GC3210D, manufactured by GL Sciences). The hydrogen sulfide concentration (ppm) within the bag was also measured using a gas detector (GX-3R Pro, manufactured by Riken Keiki Co., Ltd.).

The lower the measured hydrogen concentration, the more suppressed hydrogen production is.

Furthermore, if the concentration is less than 0.3 ppm, it is known that humans cannot smell the odor of rotten eggs, and it is evaluated as being able to prevent the generation of hydrogen sulfide.

Table 1 summarizes the evaluation results of the above oxygen reaction amount, hydrogen concentration, and hydrogen sulfide concentration.

When the iron-based mixed powder of the embodiment is compared with the powder of the comparative example, the former has a higher reactivity with oxygen, produces less hydrogen and less hydrogen sulfide.

By setting the median particle size below 400 μm, the iron-based mixed powders of Examples 3 to 10 have higher reactivity with oxygen and generate less hydrogen. Furthermore, the generation of hydrogen sulfide can be prevented.

By setting the median particle size below 200 μm, Examples 5-10 have a higher reactivity with oxygen and generate less hydrogen than Examples 1-4. This also prevents the generation of hydrogen sulfide.

It was confirmed that the above-mentioned effects can also be obtained when the sulfur-containing powder is a mixed powder of sulfur powder and silicon dioxide powder, manganese sulfide powder, or calcium sulfide powder.

Thus, the iron-based mixed powder of this embodiment has a high reactivity with oxygen and can suppress the generation of hydrogen. In addition, the iron-based mixed powder of this embodiment produces a small amount of hydrogen sulfide, which can prevent the generation of a rotten egg odor.

Furthermore, the embodiments disclosed in this specification are merely illustrative, and the present invention is not limited thereto. Modifications may be made as appropriate without departing from the scope of the present invention. (Industrial Applicability)

The present invention is applicable to iron-based mixed powder and oxygen reactant.

Claims (6)

An iron-based mixed powder comprises an iron-based powder having an oxygen to iron atomic ratio (O/Fe) of 0.800 or less, and a sulfur-containing powder having a sulfur content of 10.000 mass% to 100.000 mass%; the sulfur-containing powder content is 0.020 mass% to 5.000 mass% relative to the combined content of the iron-based powder and the sulfur-containing powder; the sulfur-containing powder comprises at least one of elemental sulfur powder, manganese sulfide powder, sodium sulfide powder, and nickel sulfide powder. The iron-based mixed powder of claim 1, wherein the sulfur-containing powder contains manganese sulfide powder. The iron-based mixed powder of claim 1 or 2, wherein the volume-based median particle size is greater than or equal to 70 μm and less than or equal to 100 μm. An oxygen reactant comprises: An iron-based mixed powder comprising: an iron-based powder having an oxygen to iron atomic ratio (O/Fe) of 0.800 or less; and a sulfur-containing powder having a sulfur content of 10.000 mass% to 100.000 mass%; the sulfur-containing powder content, relative to the total of the iron-based powder content and the sulfur-containing powder content, is 0.020 mass% to 5.000 mass%; the sulfur-containing powder contains at least one of elemental sulfur powder, manganese sulfide powder, sodium sulfide powder, and nickel sulfide powder. The oxygen reactant of claim 4, wherein the sulfur-containing powder comprises manganese sulfide powder. The oxygen reactant of claim 4 or 5, wherein the volume-based median particle size of the iron-based mixed powder is greater than or equal to 70 μm and less than or equal to 100 μm.