JPH11241111A - Production of metallic iron - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method, with which the consumption of carbonaceous reducing agent and the heat energy needed to heat-reduction are restrained to the necessary min. limit and the reduction of iron oxide can be executed in the practical scale at further lower cost and in good efficiency, at the time of producing metallic iron by heat-reducing a formed body containing the carbonaceous reducing agent and the iron oxide. SOLUTION: In the method for producing the metallic iron by heat-reducing the formed body containing the carbonaceous reducing agent and the iron oxide, an effective carbon content in the formed body is adjusted to the range of CA to [CA+0.43/(1-0.043)×T.Fe] to the necessary stoichemiometric quantity CA in order to reduce the iron oxide in the formed body. Wherein, T.Fe is the total Fe content (wt.%) in the iron oxide. The heat-reducing temp. is controlled into the higher temp. range between the temp. range of the liquidus temp. TA to (TA+50) deg.C in the Fe-C binary phase diagram and the temp. range of 1,350-1,400 deg.C in the case of assuming what the whole quantity of the effective carbon exceeding the stoichemiometric quantity is made to solid solution into the metallic iron.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a technique for obtaining metallic iron by heating and reducing iron oxide such as iron ore together with a carbonaceous reducing agent such as carbonaceous material, and more particularly, to improving iron oxide such as iron ore. When iron is obtained by heating together with a carbonaceous reducing agent such as material to obtain metallic iron, iron oxide is efficiently reduced to metallic iron with the minimum necessary amount of carbonaceous reducing agent. The present invention relates to a method capable of efficiently melting and separating a slag component mixed as a gangue component and the like to efficiently produce high-purity metallic iron.

[0002]

2. Description of the Related Art As a direct iron production method for obtaining reduced iron by directly reducing iron oxide such as iron ore and iron oxide pellets with a carbonaceous reducing agent such as carbonaceous material or a reducing gas, the Midrex method has conventionally been represented. A known shaft furnace method is known. This type of direct iron making method is a method in which a reducing gas produced from natural gas or the like is blown from a tuyere at a lower portion of a shaft furnace, and iron oxide is reduced using the reducing power to obtain reduced iron. Recently, a reduced iron production process using a coal material such as coal as a reducing agent in place of natural gas has been attracting attention.Specifically, calcined pellets such as iron ore are reduced by heating in a rotary kiln together with coal powder, The so-called SL / RN method has already been put to practical use.

As another method for producing reduced iron, US Pat. No. 3,443,931 discloses a method in which a carbon material and powdered iron oxide are mixed to form a lump and reduced by heating on a rotary hearth to produce reduced iron. A process is disclosed. In this process, fine ore and fine coal are mixed and agglomerated, and this is heated and reduced in a high-temperature atmosphere.

[0004] The reduced iron produced by these methods is used as an iron source as it is or after being shaped into a briquette or the like, and then charged into an electric furnace. In recent years, as the recycling of iron scrap has become more active, reduced iron obtained by the above method has attracted attention as a diluent for impurity elements mixed into the scrap.

[0005] However, the reduced iron obtained by the conventional reduction iron making method includes iron oxide (such as iron ore) used as a raw material.
SiO _2, Al ₂ O ₃ contained in or carbonaceous material (such as coal),
Since the slag component such as CaO is directly mixed, the iron quality (purity as metallic iron) of the product is lowered. In practical use, these slag components are separated and removed in the next smelting process. In order to meet such demands with the conventional method of producing reduced iron as described above, it is necessary to use high-grade iron ore as a raw material for producing reduced iron. Rather, the range of choice of practicable iron-making raw materials is greatly reduced.

On the other hand, as a method of directly reducing iron oxide to obtain reduced iron, a smelting reduction method such as a DIOS method is also known.
In this method, iron oxide is preliminarily reduced to an iron purity of about 30 to 50%, and then reduced to metallic iron by direct reduction reaction with carbon in an iron bath. In this method, two steps of pre-reduction and final reduction in an iron bath are indispensable, so that not only the operation is complicated, but also the molten iron oxide (FeO) present in the iron bath comes into direct contact with the refractory. Therefore, a problem that refractory wear is severe is pointed out.

Further, Japanese Patent Publication No. 56-19366 discloses that
Heating and reducing the agglomerate containing the metal oxide and the solid carbonaceous material and the slag forming material, while maintaining the shape of the agglomerate,
It discloses a method of forming a state in which metallic iron generated by reduction is wrapped in a slag shell and then melting the slag shell to separate metallic iron and slag. However, in this method, in order to prevent re-oxidation of the metal generated by the reduction, it is necessary to generate slag in an amount sufficient to completely enclose the metal. It becomes insufficient and reoxidation of the metal becomes unavoidable. In addition, depending on the heating and reducing conditions, a slag having a high FeO concentration is generated, which significantly damages the refractory lining of the equipment, which poses a serious problem in practical use.

[0008] As described above, the realization of a method of producing metallic iron having a small slag component content not only increases the added value of the product metallic iron, but also reduces the cost of iron making using an electric furnace and further reduces the metallurgy. This becomes extremely important from the viewpoint of flexibility in selecting raw materials used in iron production. In addition, minimizing the iron oxide content in the slag by-produced by heating and reduction and suppressing the erosion of refractories is extremely important in making this type of ironmaking process feasible on an industrial scale. Become.

The present inventors have paid attention to such a situation, and have found that iron purities can be obtained from iron oxide having a high iron content as well as iron ore having a relatively low iron content without causing erosion of refractories or the like. Research has been conducted in advance of the development of a technology capable of efficiently obtaining metal iron having a very high efficiency by a simple treatment. As a result of the research, the following method has been developed, and the method described in JP-A-9-256017 has been described. As suggested.

According to the present invention, when producing a metallic iron by heating and reducing an iron oxide molded body in which a carbonaceous reducing agent is present, a metallic iron outer skin is generated and grown by the thermal reduction, and the iron oxide is contained inside. Reduction is promoted until substantially no longer present, and agglomerates of generated slag are formed inside, and metallic iron skin is generated and grown by heat reduction, and reduction is progressed until substantially no iron oxide is present inside , Further heating is continued to cause the slag generated inside to flow out of the metal iron shell, to generate and grow the metal iron shell by heat reduction, and to proceed with reduction until iron oxide is substantially absent inside,
Further heating is continued to melt and separate the metallic iron and the slag, or the metallic iron outer skin is generated and grown by heat reduction, and the reduction is advanced until there is substantially no iron oxide inside, and the generated slag is formed inside. It is characterized in that agglomerates are formed and then the resulting slag is separated from the metallic iron.

[0011] In carrying out the above method, the molten slag in the inside may be caused to flow out of the metal iron shell by melting a part of the metal iron shell. In this case, the above method is carried out. In order to melt part or all of the metallic iron shell, the carbonaceous reducing agent present in the metal shell is dissolved (solid-solved) in metallic iron (this phenomenon is sometimes called "carburization"). What is necessary is just to lower the melting point of the metal sheath.

In the above disclosed invention, the preferable quantitative criterion for “promoting reduction until iron oxide substantially does not exist inside the metallic iron shell” is a heat reduction step,
"The content of iron oxide mainly composed of FeO is 5% by weight or less,
More preferably, the reduction is promoted to 2% by weight or less. "From another viewpoint, FeO in the produced slag separated from the metallic iron produced by the reduction reaction is considered.
It is desirable to carry out the reduction until the content of iron oxide mainly composed of 5% by weight or less, more preferably 2% by weight or less.

The high-purity metallic iron and produced slag obtained by this method are separated by a specific gravity difference in a heated and molten state, or are separated by cooling and then solidified by magnetic separation or the like. More than 98
% Or more, it is possible to obtain highly pure metallic iron, and according to the disclosed invention, the iron oxide content in the produced slag can be reduced as much as possible. Practical use of this technology is expected as a technology with extremely high practicality from the viewpoint of facility maintenance, without causing furnace refractory erosion.

[0014]

DISCLOSURE OF THE INVENTION The present inventors have utilized the basic technical concept of the above-mentioned disclosed invention, and in order to make it more economically and efficiently realizable on an industrial scale, in particular, reduction of iron oxide. In order to reduce the consumption of the carbonaceous reducing agent and the amount of heat consumed, further research has been conducted.

That is, in the disclosed invention, as described above, the iron oxide compact in which the carbonaceous reducing agent is present is reduced by heating, and a metallic iron shell is formed and grown around the compact, and the iron oxide is formed inside. Is a direct reduction steelmaking method based on coagulation and separation of the generated slag inside while reducing substantially no longer exists.
It is necessary to use an excessive amount of a carbonaceous reducing agent with respect to the iron oxide which is a component to be reduced contained in the compact, and in order to efficiently separate the produced metallic iron from the produced slag, the metallic iron It is effective to decrease the melting point of metallic iron by increasing the amount of solid solution of carbon (the amount of carburizing) into the iron.

For these reasons, in the above-mentioned disclosed invention, the carbonaceous reducing agent is used in an excessive amount exceeding the theoretical equivalent with respect to the raw material iron oxide. However, when the disclosed invention is put to practical use on an industrial scale, the cost ratio occupied by the carbonaceous reducing agent in the raw material is quite high, and minimizing the consumption of the carbonaceous reducing agent is necessary for industrialization of this method. It is extremely important in realizing. Further, since a large amount of heat energy is required for this heat reduction, it is extremely important to minimize the heat energy.

The present invention has been made in view of such circumstances, and an object of the present invention is to reduce the carbonaceous material when producing a metallic iron by heating and reducing a compact containing a carbonaceous reducing agent and iron oxide. It is an object of the present invention to establish a method capable of minimizing the consumption of the agent and the heat energy required for heat reduction, and performing iron oxide reduction efficiently at lower cost on a practical scale.

[0018]

Means for Solving the Problems The method for producing metallic iron according to the present invention, which can solve the above-mentioned problems, relates to a method for producing metallic iron by heating and reducing a compact containing a carbonaceous reducing agent and iron oxide. , The effective carbon amount in the molded body, the stoichiometric amount C _A required to reduce the iron oxide in the molded body,
C _A to ΔC _A + [(0.043) / (1−0.04
3)] × T. Fe｝ [where T. Fe is all F in iron oxide
e content (% by weight)], and the heat reduction temperature is set to the liquid phase in the Fe-C phase diagram when it is assumed that the excess amount of available carbon is completely dissolved in metallic iron. It is characterized in that the temperature is controlled within the temperature range of the linear temperature T _A to (T _A +50) ° C. or the higher temperature range of 1350 to 1400 ° C.

Further, when the present invention is viewed from another viewpoint, the above-mentioned heat reduction temperature is adjusted so that the effective carbon amount is C _A to ΔC _A +
[(0.024) / (1-0.024)] × T. Fe｝
When it is assumed that the effective carbon exceeding the stoichiometric amount is completely dissolved in the metallic iron, the temperature range of the liquidus temperature T _A to (T _A +50) ° C. in the Fe—C system diagram. And the effective carbon amount is ΔC _A + [(0.024) /
(1-0.024)] × T. Fe｝, ΔC _A +
[(0.043) / (1-0.043)] × T. Fe｝
When it is below, it can be positioned as a method of controlling within a temperature range of 1350 to 1400 ° C.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, in the present invention, a formed body of iron oxide (hereinafter, also referred to as iron ore) in which a carbonaceous reducing agent (hereinafter, also referred to as carbon material) is present is reduced by heating. In the production of metallic iron, the amount of carbon material in the compact is kept to a minimum and the temperature at the time of heat reduction is reduced as much as possible to reduce heat energy consumption. In the following, the reason why the carbon material amount and the heating temperature determined in the present invention are determined will be described in detail.

When a molded body containing carbon material and iron oxide is heated,
The reduction reaction proceeds according to the following reaction formula and reduced iron (metallic iron)
Is generated. FeO _x + xC → Fe + xCO (1) FeO _x + (x / 2) CO → Fe + (x / 2) CO ₂ (2) Y = y ₁ + y ₂ (3) Y: chemical equivalent (mol) of C required for reduction y ₁ : carbon amount (mol) required for the reaction of formula (1) y ₂ : carbon amount (mol) required for the reaction of formula (2)

Accordingly, the mixing ratio of the carbon material to the iron oxide in the production of a molded article containing the carbon material as the raw material for heat reduction and the iron oxide must be set to be equal to or more than the theoretical equivalent shown by the above formula (3). Must. On the other hand, excess C in the carbonaceous material blended in excess of the theoretical equivalent dissolves in the metallic iron generated by the reduction, and lowers the melting point of the metallic iron as shown in the Fe-C phase diagram of FIG. Then, when the heating temperature is higher than the melting point of the metallic iron in which C is dissolved, the metallic iron is melted and the separation from the produced slag proceeds.

That is, it is natural that the amount of the carbon material blended in the above-mentioned molded body should be equal to or more than the theoretical equivalent required for the reduction of iron oxide. This is greatly affected by the lowering of the melting point due to the solid solution and, in turn, the heating temperature for efficiently promoting the separation from the formed slag. Therefore, based on these findings, research has been conducted to clarify the optimum amount of carbon material and the heating temperature at which the reduction of iron oxide and the solid solution of C in metallic iron (and the resulting decrease in melting point) are most efficient.

As a result, first, the amount of the carbon material is equal to or more than the stoichiometric amount C _A required for the reduction of the iron oxide and ΔC _A + [(0.043) /, based on the effective carbon amount contained in the carbon material. (1
−0.043)] × T. It has been confirmed that it is most effective to keep Fe｝ or less. Here, the effective carbon amount in the carbonaceous material means a carbon content that is effectively consumed for reduction of iron oxide and carburization of metallic iron, that is, when mixed with iron oxide to produce a molded body. It means the carbon content excluding the carbon content volatilized as hydrocarbon gas or the like until the temperature reaches the temperature at which the reduction reaction starts in the heating drying step or the temperature raising step for heat reduction.

If the effective carbon content in the carbon material is less than the above stoichiometric amount C _A , the carbon content becomes insufficient and the reduction of all iron oxides cannot be completed.
The effect of lowering the heating temperature due to the melting point drop due to the solid solution cannot be expected. Then, as shown in FIG. 1, the excess available carbon exceeding the stoichiometric amount C _A dissolves in the formed metallic iron and lowers its melting point. As a result, the slag separation at a lower temperature occurs. However, the melting point drop of metallic iron due to such carburization (solid solution of C) is ΔC _A + [(0.04
3) / (1-0.043)] × T. The lower limit is at Fe｝, and the melting point rises when the amount of C solid solution further increases. That is, ΔC _A + [(0.043) / (1−0.04
3)] × T. An excess amount of available carbon exceeding Fe｝ is not only wasted in the heat reduction of iron oxide, but also becomes negative in decreasing the melting point of the produced metallic iron and the accompanying decrease in the heating temperature. Since the crushing strength of the molded article also decreases and tends to collapse during heat reduction, the upper limit of the effective carbon amount is ΔC _A + [(0.043)
/(1−0.043)]×T. Fe｝.

On the other hand, with respect to the heat reduction temperature, assuming that the excess amount of available carbon was completely dissolved in metallic iron,
Liquidus temperature T _A ~ in -C phase diagram (T _A +50)
It is necessary to control the temperature to the higher of the temperature range of 1 ° C or the temperature range of 1350 to 1400 ° C. That lower limit of the heating temperature, as a first requirement, the effective carbon of the excess amount is to be taken as the liquidus temperature T _A more in Fe-C phase diagram when it is assumed that a solid solution to the total amount of metallic iron On the other hand, if the heating temperature is lower than the liquidus temperature T _A , the metallic iron in which C forms a solid solution does not melt, so that separation from the generated slag cannot proceed. However, even if the heating temperature is equal to or higher than the liquidus temperature T _A , the heating temperature is 135
In a low-temperature range of less than 0 ° C., the solid solution rate of excess carbon is remarkably reduced.
In this case, the melting point of metallic iron does not drop to 1350 ° C. or lower, and the separation from the produced slag cannot proceed.

For such a reason, the lower limit of the heating temperature should be the higher one of the above-mentioned "liquidus temperature T _A or 1350 ° C". In consideration of application to actual operation, the upper limit of the preferable heating temperature is the higher temperature of “(T _A +50) ° C. or 1400 ° C.”, since this leads to an increase in the amount and unnecessarily increases the running cost. It is determined.

Thus, the preferred range of the effective carbon amount and the heating temperature specified in the present invention is a region shown by oblique lines in FIG. 1. By adopting the fixed carbon content and the heating temperature in the narrow range, the heat reduction of the iron oxide can be achieved. Can be efficiently performed with less carbon material and heat energy.

As is clear from FIG. 1, the hatched region showing the above-mentioned preferred heating temperature has a C solid solution content of 2.4 in Fe.
%, And when the amount of C solid solution is in the range of 0 to 2.4%, the preferable heating temperature changes along the liquidus line L. When the amount of C solid solution exceeds 2.4, the suitable heating temperature is changed. Temperature is 1350-140
It is in a certain range of 0 ° C. From such a tendency, the effective carbon amount is C _A to ΔC _A + [(0.024) / (1−0.0
24)] × T. When Fe｝, the liquidus temperature T _A to (T _A +5) in the Fe—C phase diagram when it is assumed that all available carbon exceeding the stoichiometric amount is dissolved in metallic iron.
0) Within the temperature range of ° C. and the effective carbon amount is ΔC _A +
[(0.024) / (1-0.024)] × T. Fe｝
Super, ΔC _A + [(0.043) / (1-0.043)]
× T. 1350-1400 ° C when Fe｝ or less
It can be rephrased as a method of controlling the temperature within the above range.

Examples of the carbonaceous reducing agent used in practicing the present invention include coal powder which has been subjected to a treatment such as pulverization and sieving after mining, and a material obtained by pulverizing coke which has been subjected to a heat treatment such as dry distillation. Any kind of petroleum coke or the like may be used, and for example, blast furnace dust collected as waste containing carbonaceous material may be used. However, the carbonaceous reducing agent used in the present invention is selected to have an effective carbon amount of 70% by weight or more, more preferably 80% by weight or more, and to increase the specific surface area in order to efficiently promote the heat reduction reaction. It is desirable to use a powder having a particle size of 2 mm or less, preferably 1 mm or less. Similarly, iron oxide such as iron ore is preferably used in powder form having a particle size of 2 mm or less, preferably 1 mm or less in order to similarly increase the specific surface area and enhance the reduction reaction efficiency.

In the present invention, these carbonaceous reducing agents and iron oxide are mixed in such a suitable mixing ratio as described above, and if necessary, an appropriate binder is used in combination to obtain an arbitrary shape such as lump, granule, pellet, briquette or the like. By controlling the heating and reducing temperature to a suitable range as described above in accordance with the amount of the carbonaceous reducing agent, that is, the effective carbon amount, metallic iron can be economically and efficiently produced.

[0032]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to experimental examples. However, the following examples are not intended to limit the present invention, and the present invention is not limited to the following examples. It is also possible to implement the present invention with modifications, and all of them are included in the technical scope of the present invention.

Experimental Example An iron ore having a composition shown in Table 1 was mixed with a carbon material and a binder in the ratio shown in the same table, and pellets having an average diameter of 17 mm obtained by granulation were used. Heat reduction was performed with the level changed, and the reduction and melting behavior of iron oxide was observed. Table 2 shows the mixing ratio of the carbon material, the excess carbon amount after reduction (the excess effective carbon amount with respect to the stoichiometric amount necessary for reducing the compounded iron oxide: theoretical value), and the excess carbon amount. Shows the melting point of metallic iron when it is assumed that all are dissolved in metallic iron. (Heating conditions) Heating temperature: 1200 to 1500 ° C Heating atmosphere: N ₂ Heating time: 20 minutes

[0034]

[Table 1]

[0035]

[Table 2]

The chemical composition of the reduced product and the molten state of metallic iron obtained in the above experiment are shown in Table 3, and the amount of the carbon material and the heating temperature at the time of pellet production affect the molten state of the metallic iron produced. The influence is shown as a list in FIG. 2 (Nos. 1 to 10 described in FIG. 2 correspond to the sample Nos. In Table 3). FIG. 3 is a cross-sectional photograph of the reduced product obtained in the above experiment, FIG. 4 is an excerpt of a photograph of a part of the reduced product, and FIG. 8 (FIG. 5 (A)) and its micrograph [FIG.
(B)].

In the photographs of FIGS. 3 and 5, those appearing white indicate that reduced iron was melted and agglomerated.
The black part shows the generated slag. FIG. 5 (B)
Appearing in an amoeba-like manner on the gray background indicates solid C remaining without being dissolved in metallic iron.

[0038]

[Table 3]

The analysis can be made as follows from Tables 1 to 3 and FIGS. Sample No. 1-4 are examples in which the heating temperature at the time of reduction is appropriately controlled in accordance with the amount of the carbonaceous material. In each case, the metallic iron generated by the reduction is sufficiently melted and almost agglomerated into one lump. And “T.Fe”, “MF”
e) and a “metallization ratio”, very high values are obtained.

On the other hand, sample no. Nos. 5 to 10 are comparative examples in which the heating temperature at the time of reduction is insufficient with respect to the effective carbon content of the carbonaceous material. No reduction was achieved until the iron oxide was reduced, and the reduction of iron oxide and the solid solution of C in the formed metallic iron and the resulting decrease in melting point were insufficient.
In 5, 6, and 8, the formation of metallic iron skin is partially observed, but countless metallic iron is dispersed inside, and the melting is insufficient and the separation from slag has not sufficiently progressed. Also N
o. In 7, 9, and 10, almost no metallic iron skin itself was generated, and almost no separation of metallic iron and generated slag was performed.

Further, a slag component (CaO + SiO ₂ + Al
₂ O ₃ ), sample no. In each of Examples 1 to 4 (Examples), the slag content showed an extremely low value of 1% by weight or less, and slag separation was almost completely performed. In all of the samples 5 to 10, around 7% by weight of slag was mixed, and it was confirmed that slag separation was insufficient.

Further, as is apparent from FIG. 5B (enlarged cross-sectional photograph of the reduction product obtained in No. 8), when the heating temperature during the reduction is too low, the stoichiometry required for the reduction is reduced. An excessive amount of C with respect to the stoichiometric amount of C remains in the system as a solid C without being dissolved in the metallic iron. Does not progress enough,
It can be confirmed that the melting of metallic iron is insufficient.

Table 4 below shows the results of examining the effect of the amount of the carbon material on the crushing strength of the pellet (the method of producing the pellet is the same as described above). It can be seen that the crushing strength is greatly reduced. Therefore, in order to increase the crushing strength of the pellets, to suppress the destruction and collapse of the pellets during heat reduction, and further to efficiently promote the heat reduction by powdering, the blending amount of the carbonaceous material should be minimized.

[0044]

[Table 4]

[0045]

The present invention is configured as described above. The amount of the carbonaceous reducing agent is determined by changing the amount of the stoichiometric amount required for the reduction of the iron oxide and the amount of the solid solution in the formed metallic iron. By properly controlling the heating temperature in consideration of the melting point of metallic iron accompanying the solid solution of C, the required amount of carbonaceous reducing agent is used and the slag is separated by heating and reducing iron oxide at the required heating temperature. And a more economical and practical method for producing metallic iron on an industrial scale was established.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an excess effective carbon amount and a suitable heating temperature range at the time of reduction in the method of the present invention by using an Fe—C phase diagram.

FIG. 2 is a diagram showing, in a tabular form, the effects of the excess C amount on the stoichiometric amount of C required for the reduction of iron oxide and the heating temperature at the reduction on the molten state of metallic iron produced.

FIG. 3 is a diagram showing the results of No. 3 shown in FIG. It is a cross-sectional photograph of the reduction product obtained in 1-10.

FIG. 4 is an excerpt of a part of the heat reduction product obtained in the experimental example,
It is the figure which put together the appearance photograph of the excess effective carbon amount, the heating temperature, and the reduction product in a table form.

FIG. 8A and 8B are a sectional substitute photograph and an enlarged sectional photograph of the reduction product obtained in FIG.

Continued on the front page (72) Inventor Masanori Shimizu 1 Kanazawacho, Kakogawa-shi, Hyogo Kobe Steel, Ltd. Inside the Kakogawa Works

Claims (2)

[Claims] 1. A method for producing metallic iron by heating and reducing a molded body containing a carbonaceous reducing agent and iron oxide, wherein the amount of effective carbon in the molded body is determined by reducing the amount of iron oxide in the molded body. to stoichiometry C _{a required, C a ~ {C a +} [(0.
043) / (1-0.043)] × T. Fe｝ [wherein
T. Fe represents the total Fe content (% by weight) in the iron oxide], and the heat reduction temperature is determined based on the assumption that all the effective carbon exceeding the stoichiometric amount was dissolved in the metallic iron. liquidus in the Fe-C phase diagram the temperature T _a ~
(T _A +50) ℃ temperature range, or 1350-14
A method for producing metallic iron, wherein the temperature is controlled within a higher temperature range of the temperature range of 00 ° C. 2. A method for producing metallic iron by heating and reducing a compact containing a carbonaceous reducing agent and iron oxide, wherein the amount of effective carbon in the compact is determined by reducing the amount of iron oxide in the compact. to stoichiometry C _{a required, C a ~ {C a +} [(0.
043) / (1-0.043)] × T. In addition to adjusting the heating reduction temperature to the range of Fe｝
_A to ΔC _A + [(0.024) / (1−0.024)]
× T. When Fe｝, Fe-C when it is assumed that all available carbon exceeding the above stoichiometric amount was dissolved in metallic iron.
Within the temperature range of the liquidus temperature T _A to (T _A +50) ° C. in the system phase diagram, and the effective carbon amount is ΔC _A + [(0.
024) / (1-0.024)] × T. Fe｝, △ C
_A + [(0.043) / (1-0.043)] × T. F
A method for producing metallic iron, wherein when the temperature is not more than e｝, the temperature is controlled within a temperature range of 1350 to 1400 ° C.