JP2000045008A - Production of reduced metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produced a reduced metal in a high efficiency. SOLUTION: At the time of producing a reduced metal by reducing a powdery iron-contg. material, the powdery iron-contg. material is mixed with a powdery reducing material and furthermore with an auxiliary raw material to form into a mixture of 0.4 to 1.3 basicity, which is held on a hearth for a time of >=1/3 of the total time for reducing treatment so as to control the inside temp. of the mixture >=1,200 deg.C and the reducing ratio thereof to 40 to 80%, and next, the mixture after the reduction is melted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method suitable for producing reduced metals from ores and dusts containing metals such as iron, chromium, nickel and manganese, and metal-containing substances such as sludge.

[0002]

2. Description of the Related Art Crude steel production methods are roughly classified into blast furnaces.
The converter method and the electric furnace method are known. Among them, the electric furnace uses scrap or reduced iron as an iron raw material, heats and melts them with electric energy, and in some cases, refines it into steel. At present, scrap is the main raw material,
In recent years, the use of reduced iron has been increasing due to the tight supply and demand of scrap and the flow of manufacturing high-end products by the electric furnace method.

As one of the processes for producing reduced iron, for example, JP-A-63-108188 discloses that a layer made of iron ore and a solid reducing agent is stacked on a horizontally rotating hearth and radiated from above. A method for producing reduced iron by heating and reducing iron ore by heat transfer is disclosed. This method has such advantages that the construction cost of the equipment is relatively inexpensive and the operation trouble is relatively small. In many cases, the horizontally moving hearth is in the form of a rotary hearth as shown in FIG. 1 and FIG.

[0004] On the rotary hearth 1, a layer t composed of iron ore and a solid reducing agent carried in through the charging inlet 2 is stacked, and the hearth 1 is covered by a furnace body 3 covered with refractory. A burner 4 as a heat source is installed in the upper part on the inside thereof, so that iron ore is reduced on the moving bed furnace 1. The temperature inside the furnace is usually around 1300 ° C, and after the reduction process is completed, it is cooled by a cooler on the rotary hearth to prevent oxidation after discharging outside the furnace and to improve the ease of handling. After cooling the reduced iron, the reduced iron is discharged from the outlet 5 and collected.

[0005] By the way, iron ore contains gangue, though there is a difference depending on the place of production. Coal and coal char, which are typical examples of solid reducing agents, have ash, which is a product of reduced iron. It remains as it is and is melted and removed in the electric furnace (melting furnace) in the next process, but if gangue contained in the raw ore or ash contained in the coal enters the electric furnace, it will be adjusted for basicity. At present, the amount of lime used has increased, and the cost of lime has increased and the amount of power used has to be increased by lime input. Further, in the production process of steel materials, the above-mentioned blast furnace, converter, dust and rolling in gas generated in each process of the electric furnace, etc.
In addition to iron, chrome, nickel, manganese, and other useful metals added to steel products such as oxides and hydroxides are included in sludge generated by scale, polishing, electrolysis, etc. in finishing processes such as surface treatment. However, since these dusts and sludges also contain impurities such as SiO ₂ , Al ₂ O ₃ , CaO, and carbon, it has been difficult to recover such useful metals.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a raw material ore containing gangue and ash, and a metal-containing material such as dust and sludge containing various impurities, especially a powdery metal-containing material. It is an object of the present invention to propose a novel method which can remove the gangue, ash, and impurities without using an extra step in the reduction treatment step even when using a substance.

[0007]

According to the present invention, powdery metal-containing materials (ores such as iron ore, nickel ore, chromium ore, manganese ore, iron sand, reduced iron powder, iron dust, iron sludge, etc.) can be used. ) To produce a reduced metal, a powdered metal-containing material having a basicity of 0.4 to 1.3 is used as a raw material, or a powdered metal-containing material and a powdery reducing agent ( (Coal powder, coal char, coke powder, etc. can be used) and / or powdered auxiliary material (limestone powder, quick lime powder,
Slaked lime powder, dolomite powder, etc. can be used) and the basicity adjusted to 0.4 to 1.3 is used as a raw material. From the time when the raw material enters the melting zone), the internal temperature of the raw material is 1200 ° C. or more and 1350
The method is characterized in that the reduction ratio is maintained at 40 ° C. or less at 40 ° C. or lower, and the raw material after reduction (the raw material immediately before entering the melting zone after reduction treatment) is in a molten state. It is a manufacturing method, in which a powdery reducing agent layer is formed on the hearth, and the raw material is preferably laminated thereon. In addition, if the hearth is a moving hearth that moves itself, the reduction treatment of the raw material is performed continuously. Can be done. Here, in order to bring the raw material after reduction into a molten state, it is preferable that the temperature is further higher than the temperature at which the raw material is held within the time for performing the above-described reduction treatment. In this case, the temperature is about 1450 to 1550 ° C. Would be preferred. The reason is that by setting the temperature to 1450 ° C. or higher, the fluidity of the molten material becomes good and suitable for slag and metal separation. On the other hand, when the temperature exceeds 1550 ° C., there is almost no change in slag and metal separation, This is because it becomes large and disadvantageous in cost. Further, in the present invention, it is preferable that a powdery reducing agent is formed on the hearth and the raw material is laminated thereon. This is because the powdered reducing agent formed on the hearth is used not only for reducing the metal in the raw material, but also to avoid direct contact with the refractory material forming the hearth when the raw material is melted. This prevents the hearth from being melted.

Further, in the present invention, the reduction efficiency of metal can be promoted by supplying a powdery reducing agent to the raw material after reduction, its melt, or a mixture thereof. The supply start timing of the powdery reducing agent may be performed before the raw material is melted as long as it is after the reduction as described above, or during the melting (including a state in which the raw materials are mixed), or may be performed before the start of the melting. It may be performed inside, and there is no particular limitation. It is preferred that the powdery reducing agent is added in a plurality of portions as the reduction proceeds. As the powdery reducing agent, a supply means may be provided in the upper part of the furnace body to supply the reduced raw material, its melt, or a mixture thereof from above. The supply amount per time is preferably 10% or less based on the weight of the raw material after reduction in order to prevent a heat insulating layer from being formed.

Here, the basicity is defined as (the ratio of the powdery metal-containing material in the raw material × the CaO in the powdery metal-containing material).
Weight% + powdered reducing agent ratio in the raw material x CaO weight% in the powdered reducing agent + powdered auxiliary material ratio in the raw material x CaO weight% in the powdered auxiliary material) / (ratio of powdered metal content in raw material x powdered) ₂ % by weight of SiO2 in metal-containing material + ratio of powdery reducing agent in raw material x powdery reducing agent S
₂ % by weight of iO + ratio of powdered auxiliary material in raw material x S in powdered auxiliary material
iO ₂ % by weight). In the above formula, when the amount of carbon required for reduction can be ensured or the basicity can be adjusted without adding a powdery reducing agent or a powdery auxiliary material, calculate the ratio as 0. Can be.

[0010] The above-mentioned reduction treatment refers to heating the raw material on the hearth and keeping it at a high temperature.
By maintaining the temperature at not less than 00 ° C., iron is reduced by a reducing gas such as CO and H ₂ generated from the powdery reducing agent in the raw material, and a direct reduction of part of C with iron or metal is performed. Also refers to the processing performed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS When a reduced metal after reduction is melted, gangue and ash become slag and are separated by a specific gravity difference from the molten metal. One is extremely effective.

Auxiliary materials are added to facilitate melting when reducing metals and ash are melted, and are limestone, fluorite, serpentine, dolomite, steel slag, etc., and contain CaO as a component. It is a thing. These have undergone evaporation of crystallization water and some decomposition reactions (for example, CaCO ₃ , the main component of limestone, is thermally decomposed to CaO) before melting, but maintain a solid state due to its high melting point. ing.

When the reduction treatment is performed without adjusting the basicity, the gangue in the ore and the ash of the solid reducing agent behave as follows. First, in the ore, at the stage where the reduction rate is low, gangue components such as SiO ₂ and Al ₂ O ₃ contained in the ore are melted together with FeO in the ore, but as the reduction proceeds, the Because FeO decreases and the melting point increases, it solidifies again. Further, ash remains from pulverized coal, pulverized coal char, and coke breeze used as the pulverized solid reducing agent, but the ash is mainly composed of SiO ₂ and Al ₂ O ₃ and has a high melting point. The temperature inside the moving hearth furnace is usually around 1300 ° C, which is lower than that of steelmaking converters and electric furnaces.
These gangues and ash cannot be melted. Therefore, even if the reduction proceeds, the gangue and ash do not melt, and as a result, the solid state is maintained as a whole as shown in comparison with the case where the auxiliary material is added. In addition, reduced iron from which ash has been separated cannot be obtained.

In the present invention, the basicity of the powdered metal-containing material or the raw material obtained by appropriately mixing the powdered metal-containing material with the powdered solid reducing agent, powdered auxiliary material and the like is adjusted to a range of 0.4 to 1.3. However, the reason is that by setting the basicity within this range, the melting point of slag formation of gangue and ash can be lowered, thereby facilitating melt separation of reduced iron and slag.

In order to melt the reduced metal on the hearth, from the viewpoint of thermal efficiency, it is necessary to perform the heating by local heating in as short a time as possible, so that the slag must be melted and separated quickly. However, simply adjusting the basicity of the raw material to a range of 0.4 to 1.3 and simply lowering the melting temperature of the component to be slagged in the raw material does not necessarily separate the reduced metal and slag after melting. Can not.

For this reason, according to the present invention, the internal temperature of the raw material is reduced to 120% or more during one third or more of the total time required for the reduction treatment.
0 ° C or higher, and at that time, the iron reduction rate is 40 to 80%
Hold so that

The basis of the above conditions in the present invention is based on the following experimental results. First, a mixture of iron ore, coke powder, and limestone powder having a particle size of 3 mm or less having a weight ratio of 7: 3: 1 was prepared.
The weight was continuously measured while maintaining the temperature at 00 ° C., and the progress of the reduction was investigated. As a result, the state of the reduction behavior as shown in FIG. 5 was confirmed by variously changing the type of iron ore, the average particle size, and the like. In the case where the reduction stagnation occurs, the metal and slag are clearly separated into two layers after the completion of the reduction process. However, when the initial reduction speed such as c and the high reduction rate continue for a long time, the reduction is terminated. Later observations showed that the slag and metal were hardly separated and the slag was a mixture of partially leached metal and lime.

As a result of various studies on such phenomena, there are various types of reduction patterns of iron ore, but when the reduction rate is less than 40% and the reduction rate exceeds 80%, the reduction progresses. There is not much difference, but 40% to 80
It has been clarified that the reduction may occur depending on the conditions and the reduction may proceed rapidly depending on the conditions. As shown in FIG. 5, a remarkable example in that case is that the reduction rate is 40 to 80%.
It was clarified that under the conditions where the progress of the reduction was stagnant during the period, the metal and slag obtained after the completion of the reduction were separated. That is, if the reduction rate of the iron ore is high and the reduction rate is 40 to 80% for a short time, the lime, gangue, and ash in the mixture do not sufficiently dissolve, and the lime, gangue, and ash are not sufficiently dissolved. Did not turn into slag.

This phenomenon is that when the reduction ratio of iron is relatively low at 40 to 80%, most of the iron oxides are FeO.
For existing as condition the FeO and lime, gangue, due to the fact that SiO _2, CaO in the ash, and the Al ₂ O ₃ to form a low slag composition viscosity at a low melting point, i.e., the reduction stagnation occurs In, the lime, gangue, and ash components in the mixture are dissolved by holding for a relatively long time in the presence of FeO, whereas when the reduction proceeds under conditions that do not cause reduction stagnation, iron oxide FeO and lime generated by the reduction of
It is considered that the reduction proceeds before the gangue and ash are not sufficiently dissolved, and the effect of lowering the viscosity of the slag is not sufficiently obtained, so that the metal and the slag are not separated. The reduction rate of iron in the raw material is based on the total amount of iron contained in the raw material.
This is a value obtained by subtracting from 1 the ratio of the amount of oxygen actually bonded to iron to the amount of oxygen bonded to iron when Fe ₂ O ₃ is used. Analyze the mixture for total iron weight% (TF
e), metal iron weight% (MFe), divalent iron weight% (Fe ²⁺ )
Where, 1 − ((TFe) − (MFe) − (Fe ²⁺ ) / 3) / (TFe).

As described above, when the reduction rate is kept low in the reduction operation and the basicity is adjusted in the range of 0.4 to 1.3, the raw material immediately melts after the reduction, and further, in the molten state, Metallic iron will be separated from the slag as metal. For this reason, the metal contains few gangue-derived impurities such as SiO ₂ and Al ₂ O ₃ , and a high-quality reduced metal can be produced.

Here, the reduction ratio of iron in the raw material is 40 to 80.
% Can be realized by adjusting the reduction rate according to the furnace body temperature or by adjusting the amount of the solid reducing agent mixed in the raw material. In particular, when a reducing agent in an amount smaller than the amount of the reducing agent necessary to reduce the metal oxide in the raw material is mixed, the reduction does not proceed sufficiently, and the reduction ratio of iron is low even when the temperature is kept high. Held in state.

When the reduction rate is kept low in the reduction operation, iron oxide remains in the melt in the form of FeO. The iron oxide in the melt is mixed with the slag, and if the melt is kept in a reducing atmosphere, the reduction proceeds further and shifts to metal, so it is recovered as a product from the iron in the raw material The percentage of metallic iron that can be made can be increased. In addition, since other metal oxides are in a molten state, the area of contact interface with the carbon content is significantly increased as compared with the case where they are not melted, so that reduction proceeds quickly.

When the powdery reducing agent is supplied after the raw material reduction operation, a further reduction reaction occurs (hereinafter, this is referred to as a finishing reduction reaction), but the gas generated at this time (for example, when coal is used as the reducing agent) , the melt by the gas is produced), such as CO or H ₂ is stirred strongly. By this stirring, the powdery reducing agent is taken into the melt and contributes to the reduction of the metal in the melt, but when a large amount of the powdery reducing agent remains on the surface of the melt, it becomes an insulating layer and becomes a heat insulating layer. Is not sufficiently supplied to the melt, which adversely affects the endothermic reduction reaction. On the other hand, if even a small amount of the powdery reducing agent remains on the surface of the melt, a reducing atmosphere is maintained on the surface of the melt regardless of the atmosphere in the furnace, so that reoxidation of the metal can be avoided. . For this reason, in the present invention, it is preferable to supply an appropriate amount a plurality of times as described above.

[0024]

EXAMPLE 1 A burner 4 was installed on the upper part of the hearth, and a device 6 for supplying the powdery reducing agent was installed on the upper part of the furnace. An alumina-based refractory was put on the upper surface of the hearth. 6 and 7 (section AA in FIG. 6) equipped with a rotary hearth having a diameter of 2.2 m, and And investigated the quality of the final product (reduced iron).

FIG. 8 shows a main part of the furnace shown in FIG. 6 above. The product cooled by the cooling device is crushed by the crushing device 9 provided at the discharge port and discharged by the discharging device 10. You. Ten outlets S for sampling the mixed powder in the rotary hearth furnace are provided at 10 places in the reduction zone. The reduction ratio of the mixed powder taken out of the reduction zone can be determined by chemical analysis.

Fine iron ore (3 mm mesh) in a rotary hearth furnace
The followings), powdered solid reducing agent (with a screen of 3 mm or less), and powdered limestone (with a screen of 3 mm or less) are stacked as shown in FIG. In the combustion control of the burner, the first half is adjusted between 1250 and 1350 ° C to control the reduction rate, and the second half is 1300 ° C
), Melting (The furnace temperature in the melting zone is adjusted to 1500 ° C by combustion control of the burner, combustion occurs from the stacked layers
(Mainly CO gas, natural gas as auxiliary fuel, and air as supporting gas)) and cooling. Table 1 shows the components of iron ore (gangue (containing at least 7% of SiO ₂ , Al ₂ O _3, etc.)
Table 2 shows the components of the powder solid reducing agent (containing about 5 to 11% of ash). Powdered limestone having the components shown in Table 3 was used as an auxiliary material. The operating conditions are shown in Table 4 and the operating results are shown in Table 5.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3]

[0030]

[Table 4]

[0031]

[Table 5]

In Table 4, in the column of raw material (mixed powder), the total amount of the powdered solid reducing agent, ore, and limestone is 100%, and in the column of gangue + ash, the weight% is based on the raw material.
The gangue + ash contains CaO in limestone in addition to gangue in ore and ash of the powdered solid reducing agent.

The implementation numbers 1 to 10 are within the scope of the present invention. The mixed powder in the reduction zone is sampled, and the reduction rate of the raw material is 0.4 to 0 in a time equal to or more than 1/3 of the time required for the reduction treatment (the time from the time when the raw material enters the furnace to the time when the raw material enters the melting zone). The temperature of the upper part of the furnace was adjusted so that the temperature of the raw material became 1200 ° C. or more. Under either condition, the fine ore was melted in the reduction zone, and the reduced iron was recovered in a state separated from gangue and ash. The raw material was sampled at a point in time when a half of the time required to pass through the portion of the rotary hearth furnace where the reduction operation was performed. As a result, powdered limestone was hardly found, and the powdered ore was in a partially molten state. In the raw material sampled at the reduction zone, the fine ore was in a partially molten state.

Examples Nos. 5 to 7 are the experimental results when the particle size of the raw material was changed. If the particle size of the raw material is 10 mm or less,
Melting in the reduction zone. The smaller the ore particle size, the easier it is to secure the reduction rate, and the lower the temperature of the furnace or the higher the rotation speed. Therefore, it is desirable that the particle size of the raw material is small.

Examples 8 to 10 are the results of experiments when the layer thickness of the raw material to be stacked on the hearth was changed. When the layer thickness is reduced, it is easy to secure the reduction rate, and the temperature of the upper part of the furnace can be reduced or the rotation speed can be increased.

Run Nos. 11 and 12 have the basicity of the raw material of 0.1.
4 or less or 1.3 or more. That is, it relates to processing outside the present invention. As in the execution examples 1 to 6, the raw material mixed powder was sampled at a point in time when a half of the time required to pass through the portion of the rotary hearth furnace in which the reduction operation was performed. In Run Nos. 11 and 12, the powdered limestone was almost not diffused into the molten slag. On the other hand, unlike the execution numbers 1 to 10, the fine iron ore sampled on the reduction zone side was in a re-solidified state. Further, in the finally recovered product, the gangue and ash were not separated well, and the reduction rate was lower than that of Examples 1 to 10. The temperature and the holding time of the melting zone in the rotary hearth furnace were set to the same conditions as those in Examples 1 to 4. Under these conditions, reduced iron containing high-melting gangue that would resolidify cannot be melted, and since the reduction rate is low, a reduction reaction occurs even if it is held in a high-temperature part, and it is supplied from outside. It is considered that the temperature of the mixed powder hardly rises due to the absorption of the heat.

In the execution number 13, the time during which the reduction ratio of the raw material is 0.4 to 0.8 in the reduction zone in the rotary hearth furnace is less than one third of the total reduction time. As a result of sampling the raw material at a point in time when half of the time passed through the portion of the rotary hearth furnace where the reducing operation was performed, it was found that the powdered limestone was almost as it was when it was first added. On the exit side of the reduction zone, the fine ore was supplied with execution numbers 11 and 12.
Similarly, it was sampled in a re-solidified state. Also in this method, when the time of keeping the material in the reduction zone of the rotary hearth furnace was set to 20 minutes, gangue and ash were not well separated in the finally recovered product.

[0038] In the working number 14, 50% of the time of passing through the portion where the reducing operation is performed in the moving hearth is reduced to 0.4%.
It is 0.8. However, in most parts, the temperature inside the raw material is 1200 ° C. or less. That is, it relates to processing outside the present invention. In this method, the ore in the middle of reduction has a low temperature, and slag and the like are not partially melted. Reduced iron could not be recovered with gangue and ash separated.

Run No. 15 shows that the reduction rate is 0.4 to 0.8 inside the reduction zone and the temperature of the raw material is 1200
The time during which the temperature was higher than 0 ° C. was 8% of the total reduction time. That is, it relates to processing outside the present invention. By increasing the residence time in the reduction zone to 25 min, the reduced iron is melted in the furnace and the gangue and ash are removed even if the temperature and the holding time in the melting zone are the same as those in the execution numbers 1 to 6. Reduced iron could be recovered in a separated state. However, when the operation is performed with the same hearth floor area, the longer time required for the reduction means that the productivity has decreased.

The working numbers 16 and 17 show the results within the scope of the present invention. The amount of the reducing agent in the raw material is slightly insufficient to reduce the blended ore, and the reduction rate at the stage when the reduction process is completed is about 0.8, and although the reduction rate is low, In any of the conditions, the recovered reduced iron was in a state where slag and metal were separated.

Example No. 18 shows the result of the comparative example. In this example, the reducing agent is sufficiently compounded,
Since the particle diameter of the raw material was small, the reduction proceeded remarkably, so that the reduction rate in the reduction zone was 0.4 to 0.8, and the ratio of the time during which the internal temperature of the raw material was 1200 ° C. or more was 11%.
Therefore, the reduced iron did not melt on the exit side of the reduction zone or on the exit side of the molten zone.

In the embodiment No. 19, the device 6 for supplying the powdery reducing agent is arranged at an intermediate position from the entrance side to the exit side of the melting zone to reduce the reducing agent (carbon material) from above. It is within the scope of the present invention that is fed at a rate of 3% by weight of the raw material. In this example, it was confirmed that the amount of FeO contained in the slag was further reduced and the ratio of metal recovered was increased.

In the embodiment No. 20, the device 6 for supplying the powdery reducing agent is arranged at an intermediate position from the entrance side to the exit side of the melting zone to reduce the reducing agent (carbon material) from above. The raw material is supplied under the condition of 10% of its weight and falls within the scope of the present invention. In this example, although the amount of the solid reducing agent contained in the raw material is small, the reduction ratio of iron on the melting zone side is about 90%, but the metal is supplied by supplying the reducing agent from above the raw material. Thus, reduced iron separated into slag was obtained. Further, the ratio of iron recovered as metal was as high as in the above-mentioned Example No. 19.

Example 2 Using stainless steel dusts A and B having the compositions shown in Table 6 as raw materials, operation was carried out under the conditions shown in Table 7 using the same equipment as in Example 1 above. Table 8 shows the results.

[0045]

[Table 6]

[0046]

[Table 7]

[0047]

[Table 8]

The run numbers 21 and 22 in Table 8 show the results of operation under the conditions specified in the present invention. In this example, the melting of reduced iron can be achieved without any problem, and The iron recovery rate of iron was good, and metal components such as chromium and nickel in the raw material could be recovered.

The stainless steel dusts A and B used in Example 2 contain metal oxides such as chromium and nickel in addition to iron oxides, and SiO ₂ and CaO as gangue components. Therefore, the basicity of the mixed powder falls within the range of 0.4 to 1.3 without adding any powdery auxiliary material, and particularly, stainless dust A has carbon necessary for reduction treatment. Therefore, the reduction treatment can be performed without adding a solid reducing agent, and the reduced iron product obtained in this operation contains chromium and nickel, and thus can be used particularly suitably as a raw material for stainless steel.

[0050]

According to the above examples, the basicity is 0.4
-1.3 on the hearth for more than one-third of the time from the start of heating to entering the melting zone,
By melting at a temperature of 1350 ° C. while maintaining a reduction ratio of 40 to 80%, melting of the raw material is promoted, and slag,
Good metal separation. Therefore, it is possible to efficiently produce a good quality reduced metal free of impurities such as gangue and impurities contained in iron ore and iron making dust, and ash contained in the solid reducing agent.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a conventional rotary hearth furnace.

FIG. 2 is a diagram showing a cross section taken along line AA of FIG. 1;

FIG. 3 is a diagram showing a reduction situation of iron ore.

FIG. 4 is a diagram schematically showing a reduction experiment apparatus.

FIG. 5 is a graph showing a relationship between an elapsed time and a reduction rate.

FIG. 6 is a diagram showing a configuration of a rotary hearth furnace suitable for carrying out the present invention.

FIG. 7 is a diagram showing a cross section taken along the line AA of FIG. 6;

FIG. 8 is a diagram showing a configuration of a main part of FIG. 6;

FIG. 9 is a view showing a loading state of raw materials.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Moving hearth 2 Charging device 3 Furnace body 4 Burner 5 Discharge device 6 Powdery reducing agent supply device 7 Single layer of powdered solid reducing agent 8 Mixture composed of iron ore, powdered limestone and powdered solid reducing agent 9 Crusher 10 Discharge device S Sampling and measuring port t Layer composed of iron ore and solid reducing agent

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mikiharu Takeda 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Pref.

Claims (3)

[Claims] 1. A method for producing a reduced metal by reducing a powdery metal-containing material containing iron, comprising: a powdery metal-containing material having a basicity of 0.4 to 1.3; A mixture having a basicity of 0.4 to 1.3 by mixing a powdery reducing agent and / or a powdery auxiliary raw material is used as a raw material, and this is reduced to 1/3 of the total time required for the reduction treatment on the hearth.
In the above time, the internal temperature of the raw material is 1200 ° C. or more,
A method for producing a reduced metal, comprising: maintaining the iron reduction ratio at 1350 ° C. or lower to be 40 to 80%, and then melting the reduced material. 2. The method for producing reduced metal according to claim 1, wherein a layer of the powdery reducing agent is formed on the hearth, and the raw material is laminated thereon. 3. The method for producing a reduced metal according to claim 1, wherein a powdery reducing agent is supplied onto the reduced raw material, its melt, or a mixture thereof.