JP2014043646A - Process of producing metallic iron - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process of producing metallic iron by agglomerating a mixture including an iron oxide-containing material and a carbonaceous reductant, heating the resulting agglomerates in a moving-hearth heating furnace, separating the product discharged from the furnace into metallic iron and slag, and recovering the metallic iron, in which the metallic iron is efficiently recovered from the discharged product.SOLUTION: A process of producing metallic iron includes the steps of: agglomerating a mixture including an iron oxide-containing material and a carbonaceous reductant; introducing the resulting agglomerates into a moving-hearth heating furnace, and melting the agglomerates by heating to form molten metallic iron, molten slag, and reduced agglomerates; cooling the resulting mixture; discharging the solids obtained by cooling from the moving-hearth heating furnace; crushing the discharged solids including metallic iron, slag, and a hearth covering material, discharged from the moving-hearth heating furnace, using a crusher; and recovering metallic iron through selection of the resulting crushed solids with a separator.

Description

  The present invention relates to a method for producing metallic iron by heating an agglomerate obtained by agglomerating a mixture containing an iron oxide-containing substance and a carbonaceous reducing agent in a moving hearth type heating furnace.

  Methods for producing metallic iron from an iron oxide-containing material such as iron ore are classified into several types according to a method for separating a gangue component in the iron oxide-containing material.

  The method that can produce metallic iron in the largest amount is an integrated iron making method using a blast furnace. This method uses high-grade iron ore with low gangue components, or iron oxide-containing materials composed of iron ore whose iron grade has been improved by beneficiation, and these are heated in a blast furnace, reduced and melted, It separates into a gangue component and pig iron (carbon saturated iron) in a molten state to produce metallic iron.

  Next, a method capable of producing a large amount of metallic iron is a gas DR method using natural gas. In this method, pellets made by burning and solidifying extremely high-quality iron ore are reduced using natural gas to reduce pellets, which are then charged into an electric furnace, and melted and smelted to completely remove the gangue components. The steel (low carbon steel) separated into two is manufactured.

  As a method for producing metallic iron developed in recent years, an agglomerate obtained by mixing an iron oxide-containing material such as iron ore and a carbonaceous reducing agent such as a carbonaceous material at a high temperature of about 1300 ° C. is reduced. There are a FASTMET method for producing a metal and an ITmk3 method for producing a metal iron nugget (granular metal iron) by further heating and melting the reduced agglomerate.

  In the FASTMET method, steel and gangue components can be completely separated by melting and refining the obtained reduced agglomerates in an electric furnace. This method is similar to the gas DR method described above in that all the gangue components in the reduced agglomerate are brought into the electric furnace, but the gangue components in the carbonaceous reductant are reduced. It differs in that it exists in the composition. In the gas DR method and the FASTMET method, when a large amount of gangue components are brought into the electric furnace, the heat of dissolution in the electric furnace increases, and therefore, it is required to use a raw material having less gangue components.

  On the other hand, since the ITmk3 method is separated into metallic iron and slag on the hearth in the heating furnace, it is characterized in that slag is hardly brought into the steelmaking process, and is similar to the blast furnace method described above. However, in the blast furnace method and the ITmk3 method, since the material is heated at a high temperature, the energy increases when there are many gangue components in the raw material. Therefore, it is required to use a raw material having a small gangue component.

Thus, the gangue component contained in the raw material is required to be as small as possible in both the FASTMET method and the ITmk3 method. For example, a reduced product obtained by heating and reducing an agglomerate containing iron ore with a gangue component of 9% (total amount of SiO ₂ and Al ₂ O ₃ ) and coal with an ash content of 10% Since it contains 15% (total amount of SiO ₂ and Al ₂ O ₃ ), it is difficult to use it as an iron raw material in both electric furnaces and blast furnaces.

  Patent Documents 1 to 3 are known as techniques for producing metallic iron by heating an agglomerate in which an iron oxide-containing substance and a carbonaceous reducing agent are mixed.

  In Patent Document 1, a mixture containing an iron oxide raw material and coal is subjected to a heat reduction treatment in a high-temperature atmosphere, the obtained reduced iron is pulverized, and then the particle size is selected with a predetermined particle size as a boundary. Have been described. Specifically, the particle size sorter separates and sorts the particles into particles having an average particle size exceeding 100 μm and particles having an average particle size of 100 μm or less. Then, particles having an average particle size of 100 μm or less are separated by magnetic force into strong magnetic particles containing a large amount of iron and weak magnetic particles having a small amount of iron. Magnetic deposit particles are used as reduced iron. On the other hand, weakly magnetized particles are low in iron content and high in slag content, so they are reused as cement or asphalt.

  In Patent Document 2, a carbon-containing pellet composed of a plurality of types of dust and carbon material is produced, and this is reduced in a rotary hearth-type firing furnace at a temperature of 1250 to 1350 ° C. Dust is reduced with carbonaceous material, and metallic iron particles aggregated by intragranular mass transfer are used to naturally separate metallic iron particles from the low melting point slag containing FeO produced from dust gangue using the action of natural separation. A method for producing high-grade reduced iron from iron-making dust that is extracted to produce high-grade granular reduced iron is described.

  In Patent Document 3, a carbon-containing pellet made of iron ore and a carbonaceous material is manufactured, and this is reduced at a temperature of 1250 to 1350 ° C. in a rotary hearth-type firing furnace, and the furnace temperature is further increased to 1400. A method is described in which high temperature granular metallic iron is obtained by raising the temperature to 1500 ° C. to melt and agglomerating metallic iron.

JP 2002-363624 A Japanese Patent Laid-Open No. 10-147806 JP 2002-30319 A

  In the Example described in the said patent document 1, it aims at manufacturing a reduced pellet by setting the heating temperature to 1200-1300 degreeC, and considering to isolate | separate into metallic iron and slag on the hearth of a heating furnace is considered. Not. Moreover, although the roll press is used for the grinding | pulverization, the use conditions are not disclosed and the grinding methods other than a roll press are not mentioned. Furthermore, according to the examples, even if the purity of iron having a particle size of 100 μm or more is high, the purity of iron remains at 76 to 90%, and metallic iron of this degree of purity can be used as a steelmaking raw material. Have difficulty. The reason why the iron purity remains at 76 to 90% is considered to be because the heating temperature and the pulverization method are not appropriate.

  Patent Document 2 describes that a reduced iron having a diameter of 5 mm or more is recovered as a product by screening from reduced iron obtained in a rotary hearth-type firing furnace using a screen. This technology produces molten iron and molten slag on the hearth and belongs to the ITmk3 method. However, this document describes that the metal iron product is recovered from the heated reduced product discharged from the reduction furnace using a sieve and a magnetic separator, but does not describe the crushing process.

  Patent Document 3 discloses a method of separating reduced iron and slag by completely melting reduced iron. However, this document only describes the separation of granular metallic iron and by-product slag generated in the furnace using a magnetic separator and a sieve, and does not describe the crushing process.

  The present invention has been made paying attention to the above-mentioned circumstances, and the object thereof is to move an agglomerate obtained by agglomerating a mixture containing an iron oxide-containing substance and a carbonaceous reducing agent to a moving hearth type heating furnace. In order to separate the waste discharged from the furnace into metallic iron and slag, and recover the metallic iron to produce metallic iron, the metallic iron is efficiently recovered from the above-mentioned discharged waste. It is in providing the method of manufacturing.

  The method for producing metallic iron according to the present invention that has solved the above-mentioned problems includes a step of agglomerating a mixture containing an iron oxide-containing substance and a carbonaceous reducing agent, and the obtained agglomerate is transferred to a moving hearth. A step of charging and heating the molten iron to melt the agglomerate to form molten metal iron, molten slag, and a reduced agglomerate; cooling the resulting mixture; Using a crusher, the solid matter obtained is discharged from the moving hearth-type heating furnace, and the discharged material containing metallic iron, slag, and flooring material discharged from the moving hearth-type heating furnace is used. The present invention has a gist in that it includes a step of crushing and a step of selecting the obtained crushed material using a separator and recovering metallic iron.

  The step of dividing the discharge containing the metallic iron, slag, and floor covering material discharged from the moving hearth heating furnace into a sieve and a sieve using a sieve a, and the obtained sieve on a crusher And crushing using a separator, and separating the obtained crushed material using a separator to collect metallic iron.

  As the crusher, for example, a hammer mill, a cage mill, a rotor mill, a ball mill, a roller mill, or a rod mill is preferably used.

  The sieve top preferably contains 95% or less iron in terms of iron.

  Prior to crushing the sieve, the magnetized material may be collected on the sieve using a magnetic separator to recover the magnetized material, and the recovered magnetized material may be crushed.

  As the separator, for example, a magnetic separator, a wind separator, a sieve b, or the like can be used. After performing sieving using the sieve b, the lower part of the sieve may be magnetically collected using a magnetic separator to recover metallic iron. As the sieve b, for example, a sieve having an opening of 1 to 8 mm can be used. You may further include the crushing process which grind | pulverizes the magnetic deposit obtained by magnetic separation using the said magnetic separator using a grinder.

  The pulverized product obtained in the pulverization step may be pulverized again using a pulverizer. The pulverized product obtained in the pulverization step may be magnetically collected using a magnetic separator to recover the magnetic deposit. The recovered magnetic deposit may be agglomerated.

  As the pulverizer, for example, a ball mill, a rod mill, a cage mill, a rotor mill, or a roller mill can be used.

  The above-mentioned problems include the step of agglomerating a mixture containing an iron oxide-containing substance and a carbonaceous reducing agent, charging the obtained agglomerate into a moving hearth type heating furnace, and heating the agglomerate. A step of melting to form molten metal iron, molten slag, and reduced agglomerates; a step of cooling the resulting mixture; and a solid obtained by cooling is discharged from the moving hearth furnace Obtained by the sieving step, and the sieving step of sieving the waste containing the metallic iron, slag, and floor covering material discharged from the moving hearth heating furnace using a sieve. It is also possible to solve the problem by a method for producing metallic iron, including a step of collecting the metallic iron by separating the sieved screen using a separator.

  As the separator, a magnetic separator may be used, and a magnetic deposit obtained by magnetic separation with the magnetic separator may be recovered as the metallic iron. You may include the process of grind | pulverizing the collect | recovered magnetic deposits using a grinder, and the process of classifying the obtained grind | pulverized material using a separator and collect | recovering metallic iron.

  You may further include the process of grind | pulverizing at least one part of the sieving obtained by the said sieving process using a grinder. The pulverized product obtained in the step of pulverizing using the pulverizer may be magnetically selected using a magnetic separator, and the obtained magnetic deposit may be recovered. Moreover, you may grind | pulverize again the ground material obtained at the process grind | pulverized using the said grinder using a grinder.

  The recovered metallic iron or the recovered magnetic deposit may be agglomerated.

  As the pulverizer, one that adds at least one selected from the group consisting of an impact force, a friction force, and a compression force to the magnetic deposit can be used. For example, a ball mill, a rod mill, a cage mill, a rotor mill, or a roller mill is preferably used as the pulverizer.

  As the sieve a, it is preferable to use a sieve having an opening of 2 to 8 mm.

  According to the manufacturing method of the present invention, since the metal iron, slag, and floor covering material discharged from the moving hearth heating furnace are appropriately crushed or crushed, Metallic iron can be recovered efficiently.

FIG. 1 is a drawing-substituting photograph in which the appearance of metallic iron D obtained in the example is photographed. FIG. 2 is a graph showing the particle size distribution of magnetized and non-magnetized articles. FIG. 3 is a drawing-substituting photograph in which the magnetic deposit obtained in the example is photographed. FIG. 4 is a graph showing the relationship between the grinding time and the slag rate. FIG. 5 is a graph showing the particle size distribution of magnetized and non-magnetized articles. FIG. 6 is a schematic view showing another manufacturing process of metallic iron. (A) and (b) of Drawing 7 are mimetic diagrams showing other manufacturing processes of metallic iron. FIG. 8 is a schematic view showing another manufacturing process of metallic iron. FIG. 9 is a schematic view showing an overall image of a manufacturing process of metallic iron.

  The present inventors heated an agglomerate obtained by agglomerating a mixture containing an iron oxide-containing substance and a carbonaceous reducing agent in a moving hearth-type heating furnace, and melted the agglomerate to obtain molten metal iron, After the slag and reduced agglomerates are formed, the resulting mixture is cooled in the furnace to form solids, and then discharged from the moving hearth heating furnace. In order to improve the recovery efficiency of metallic iron and improve the productivity of metallic iron, we have made extensive studies. As a result, if the metal iron, slag, and waste material including flooring material discharged from the moving hearth furnace is properly crushed or crushed, the recovery efficiency of metal iron is increased, and metal iron is recovered. It has become clear that the productivity can be improved, and the present invention has been completed.

  Hereinafter, after explaining the background to the completion of the present invention, the features of the present invention will be described in detail.

  First, as a result of various studies by the present inventors, an agglomerate containing an iron oxide-containing substance and a carbonaceous reducing agent was charged into a moving hearth-type heating furnace and heated to be melted. It turned out that iron aggregates and a particle size becomes about 2-8 mm or more. Therefore, metallic iron can be efficiently recovered by collecting those discharged from the moving hearth heating furnace with a particle size of about 2 to 8 mm or more.

  However, even if the agglomerate is heated at a high temperature of about 1350 to 1500 ° C. in the moving hearth type heating furnace, the total amount of the agglomerate is kept at a constant temperature in a steady state. This is difficult due to fluctuations in the installation conditions such as the amount and overlap. For this reason, in order to reduce the iron oxide contained in the agglomerate and separate the entire amount into molten metal iron and molten slag on the hearth of the moving hearth heating furnace, it is the lowest temperature among the agglomerates. It is necessary to raise the temperature of the agglomerate until the metal iron and slag are melted together, or to increase the heating time. However, excessively high temperature heating and prolonged heating time are not practical because a large amount of heat energy is required. Therefore, it is considered difficult to ship the entire amount of iron oxide contained in the agglomerate as metallic iron having a particle size of about 2 to 8 mm or more and to ship as a product having high iron purity. That is, even if the particle size is about 2 to 8 mm or more, 20-50% of the iron contained in the agglomerate becomes deformed granular iron containing slag, or reduced iron is agglomerated. It becomes an iron lump with slag attached to a combination of multiple agglomerates (hereinafter sometimes referred to as reduced agglomerates), or metallic iron that leaves the outer shell of reduced iron. . Thus, when incomplete metallic iron in which slag coexists is mixed, the iron purity of the metallic iron product is lowered even if the particle size is about 2 to 8 mm or more.

Therefore, in the present invention, after the metal iron and slag discharged from the moving hearth heating furnace are crushed using a crusher and then sorted using a separator, the metal iron can be efficiently recovered. It became clear. That is, the slag ratio [(SiO ₂ + Al ₂ O ₃ ) / T. Fe × 100] was calculated to be 1.68%. When this discharged material was crushed using a crusher and then magnetically selected using a magnetic separator as a separator, the slag ratio contained in the magnetic deposit was 0. Reduced to 72%. When the particle size is about 2 to 8 mm or more and the slag is sufficiently separated, the slag rate contained in the granular metallic iron can be suppressed to 0.20% or less, but if the slag rate is about 0.72%, Even if it is used as a raw material for a melting and refining furnace, it can be used economically.

  On the other hand, when agglomerates are heated in a moving hearth furnace, powders and fragments derived from agglomerates are sent into the furnace together with agglomerates into metallic iron, and during the reduction process Some of the metallic iron produced may become fine metallic iron having a particle size of 2 mm or less in the furnace. In addition, the agglomerates reduced in the furnace may produce fine metallic iron having a particle size of 2 mm or less due to mechanical impact when discharged from the moving hearth-type heating furnace. Of the discharge discharged from the moving hearth heating furnace, the discharge with a particle size of about 2 mm or less contained fine metallic iron, but it was sent into the furnace to protect the hearth. Mainly used flooring materials, hearth materials, slag, etc., they were reused as flooring materials after sieving and magnetic selection. When trying to recover the metallic iron contained in the magnetic deposit obtained by magnetic separation, the magnetic deposit contains a lot of slag (slag ratio is about 14%, for example), so it is separated into metallic iron and slag. When the operation is required and the slag is not removed, the metal iron has a low commercial value. Since the slag contained in these magnetic deposits adheres to the surface of the metal iron, for example, as in a ball mill or a rod mill, pulverization is performed by adding at least one selected from the group consisting of impact force, friction force, or compression force It was found that the slag could be removed using a machine.

  As described above, in the present invention, since the crushing or pulverization is appropriately performed with respect to the metal iron production method using the conventionally known moving hearth type heating furnace, the amount of slag contained in the metal iron is reduced. In addition to greatly improving the added value of metallic iron, it is possible to reduce variations in the quality of metallic iron due to operational fluctuations in the moving hearth furnace.

  The present invention will be described below.

With the method for producing metallic iron according to the present invention,
A process of agglomerating a mixture containing an iron oxide-containing substance and a carbonaceous reducing agent (hereinafter sometimes referred to as an agglomeration process);
A step of charging the obtained agglomerate into a moving hearth type heating furnace and heating the molten agglomerate to form molten metal iron, molten slag, and a reduced agglomerate (hereinafter, heating step) And)
A step of cooling the obtained mixture (hereinafter sometimes referred to as a cooling step);
A step of discharging the solid obtained by cooling from the moving hearth-type heating furnace (hereinafter sometimes referred to as a discharge step);
A step of crushing the discharge containing metal iron, slag, and floor covering material discharged from the moving hearth heating furnace using a crusher (hereinafter sometimes referred to as a crushing step);
A process of collecting the obtained crushed material using a separator and recovering metallic iron (hereinafter sometimes referred to as a first metallic iron recovery process);
There is a feature in including.

[Agglomeration process]
In the agglomeration step, a mixture containing the iron oxide-containing substance and the carbonaceous reducing agent is agglomerated to produce an agglomerate.

  Specific examples of the iron oxide-containing material include iron ore, iron sand, iron-making dust, non-ferrous refining residue, and iron-making waste.

  As said carbonaceous reducing agent, coal, coke, etc. can be used, for example.

  The said carbonaceous reducing agent should just contain the quantity of carbon which can reduce | restore the iron oxide contained in the said iron oxide containing substance. Specifically, the iron oxide contained in the iron oxide-containing substance may be contained in an excess of 0 to 5% by mass with respect to the amount of carbon that can be reduced.

  It is preferable to add a melting point adjusting agent to the mixture containing the iron oxide-containing substance and the carbonaceous reducing agent.

  The melting point modifier means a substance that affects the melting point of components (particularly gangue and ash) other than iron oxide contained in the agglomerate, excluding substances that affect the melting point of metallic iron. That is, by adding a melting point adjusting agent to the above mixture, the melting point of components (particularly, gangue and ash) other than iron oxide contained in the agglomerate is affected, and for example, the melting point can be lowered. Thereby, melting of gangue and ash is promoted to form molten slag. At this time, a part of the iron oxide is dissolved in the molten slag and reduced in the molten slag to become metallic iron. The metallic iron produced in the molten slag is agglomerated as solid reduced iron by coming into contact with the metallic iron reduced in the solid state.

As the melting point adjusting agent, it is preferable to use one containing at least a CaO supply substance. Examples of the CaO supply substance include at least one selected from the group consisting of CaO (quick lime), Ca (OH) ₂ (slaked lime), CaCO ₃ (limestone), and CaMg (CO ₃ ) ₂ (dolomite). It is preferable to do.

As the melting point adjusting agent, only the CaO supply substance may be used, or in addition to the CaO supply substance, for example, an MgO supply substance, an Al ₂ O ₃ supply substance, a SiO ₂ supply substance, or the like can be used. . MgO, Al ₂ O ₃ , and SiO ₂ are also substances that affect the melting point of components (particularly gangue) other than iron contained in the agglomerate, similar to CaO.

As the MgO supply substance, it is preferable to blend at least one selected from the group consisting of MgO powder, Mg-containing substance extracted from natural ore or seawater, and MgCO ₃ , for example. As the Al ₂ O ₃ supply substance, for example, Al ₂ O ₃ powder, bauxite, boehmite, gibbsite, diaspore and the like are preferably blended. As the SiO ₂ supply substance, for example, SiO ₂ powder or silica sand can be used.

  The agglomerate may further contain a binder or the like as a component other than the iron oxide-containing substance, the carbonaceous reducing agent, and the melting point adjusting agent.

  As the binder, for example, polysaccharides (for example, starch such as corn starch and wheat flour, molasses, etc.) can be used.

  The iron oxide-containing substance, the carbonaceous reducing agent, and the melting point adjusting agent are preferably pulverized in advance before mixing. For example, the iron oxide-containing material may be crushed so that the average particle size is 10 to 60 μm, the carbonaceous reducing agent is average particle size is 10 to 60 μm, and the melting point adjuster is average particle size is 5 to 60 μm. Recommended.

  The means for pulverizing the iron oxide-containing material or the like is not particularly limited, and known means can be employed. For example, a rod mill, a roll crusher, a ball mill or the like may be used.

  As a mixer which mixes the said mixture, a rotating container type mixer and a fixed container type mixer can be used, for example.

  As the rotary container type mixer, for example, a rotary cylinder type, double cone type, V type mixer or the like can be used.

  As the fixed container mixer, for example, a mixer provided with rotating blades (for example, a bowl) in a mixing tank can be used.

  As the agglomerating machine for agglomerating the mixture, for example, a dish granulator (disk granulator), a cylindrical granulator (drum granulator), a twin roll briquette molding machine or the like is used. be able to.

  The shape of the agglomerate is not particularly limited, and may be, for example, a lump shape, a granular shape, a briquette shape, a pellet shape, a rod shape, or the like, and preferably a pellet shape or a briquette shape.

[Heating process]
In the heating step, the agglomerate obtained in the agglomeration step is charged into a moving hearth heating furnace, and the agglomerate melts to obtain molten metal iron, molten slag, and reduced agglomerate. Heat until formed.

  The moving hearth type heating furnace is a heating furnace in which the hearth moves in the furnace like a belt conveyor, and examples thereof include a rotary hearth furnace and a tunnel furnace.

  The rotary hearth furnace is a furnace whose outer shape is designed to be circular (donut shape) so that the start point and end point of the hearth are in the same position, and the agglomerate supplied on the hearth Is heated and reduced during one round of the furnace to produce metallic iron (for example, sponge-like iron or granular metallic iron). Therefore, the rotary hearth furnace is provided with charging means for supplying the agglomerate into the furnace on the most upstream side in the rotation direction, and the most downstream side in the rotation direction (since it is a rotating structure, Discharging means is provided immediately upstream of the means).

  The tunnel furnace is a heating furnace in which the hearth moves in the furnace in a linear direction.

  The temperature at which the agglomerate is heated in the moving hearth type heating furnace may be, for example, 1350-1500 ° C. When the heating temperature is lower than 1350 ° C., it becomes difficult to melt the agglomerate. On the other hand, even if the heating temperature exceeds 1500 ° C., energy is wasted and furnace damage may occur.

  It is also a preferable aspect that a floor covering material is laid on the hearth of the moving hearth heating furnace prior to charging the agglomerate into the furnace. By laying the floor covering material, it is possible to protect the hearth of the mobile hearth heating furnace.

  As the floor covering material, refractory particles can be used in addition to those exemplified above as the carbonaceous reducing agent.

  The particle size of the floor covering is preferably 3 mm or less so that the agglomerate and the melt thereof do not sink. About the minimum of a particle size, it is preferable that it is 0.5 mm or more so that it may not be blown away with the combustion gas of a burner.

[Cooling process]
In the cooling step, the mixture (ie, molten metal iron, molten slag, and reduced agglomerate) obtained in the heating step is cooled in a moving hearth type heating furnace.

  Although the cooling means is not particularly limited, for example, a cooling chamber configured to cool a room through a refrigerant on a wall surface without providing a combustion burner may be provided on the downstream side of the moving hearth type heating furnace.

[Discharge process]
In the discharging step, the solid matter obtained by cooling in the cooling step is discharged from the moving hearth type heating furnace. The discharged solid matter may be further cooled outside the moving hearth heating furnace.

[Crushing process]
In the crushing step, the solid matter discharged from the moving hearth heating furnace in the discharging step (that is, the discharged matter including metal iron, slag, and flooring material) is crushed using a crusher.

  As the crusher, it is preferable to use a crusher configured to apply an impact to an object. More preferably, it is preferable to use a crusher configured to apply a strong impact to the object. As the crusher, for example, a hammer mill, a cage mill, a rotor mill, a ball mill, a roller mill, or a rod mill may be used. Furthermore, it is desirable to use a hammer mill, a cage mill, or a rod mill from the viewpoint of impact force and durability.

  When using a hammer mill as the crusher, it is preferable to crush the rooster at an interval of 5 to 20 mm. If the gap of the rooster is made too large, the ratio of discharged matter that is discharged almost without impact by the crusher increases, so the upper limit is preferably 20 mm. On the other hand, if the gap of the rooster is made too small as less than 5 mm, it is necessary to repeatedly apply impact until the particle diameter becomes smaller than the gap, which leads to excessive crushing and wear of equipment and use of a large amount of energy. Therefore, the lower limit is preferably 5 mm. The gap of the rooster is more preferably 10 to 15 mm. This is because when the temperature varies under standard operating conditions, the ratio of the particle size of 10 to 15 mm in the discharge is about 50%.

[First metal iron recovery process]
In the first metallic iron recovery step, the crushed material obtained in the crushing step is selected using a separator to recover metallic iron. That is, the metal iron recovered from the crushed material has a low slag content and can be used as it is.

In the present invention,
The effluent containing metallic iron, slag, and floor covering material discharged from the moving hearth heating furnace is sieved (ie, powder remaining on the sieve) and sieved (ie, sieve) using sieve a. (Powder that has passed through) (hereinafter sometimes referred to as sieving step),
A step of crushing the obtained sieve using a crusher (crushing step);
A process of collecting the obtained crushed material using a separator and recovering metallic iron (metallic iron recovery process);
May be included.

[Sieving process]
In the sieving step, the slag discharged from the moving hearth heating furnace is subjected to sieving using the sieve a.

  As the sieve a, it is preferable to use a sieve having an opening of 2 to 8 mm. If the mesh opening is less than 2 mm or more than 8 mm, it will be difficult to increase the recovery efficiency of metallic iron even if pulverization or magnetic separation is combined, as will be described later.

  The sieve obtained in the sieving step contains 95% or less of iron in terms of iron. On this sieve, molten metal iron, molten slag, incompletely molten metal iron, incompletely molten iron Includes slag.

  Prior to crushing with the crusher, the sieve obtained in the sieving step may be magnetically separated using a magnetic separator to crush the recovered magnetic deposit. The non-magnetized material collected by magnetic separation at this time is pulverized using a pulverizer, and the obtained pulverized material may be magnetically selected again using a magnetic separator. By repeating the pulverization and magnetic separation, the separability of metallic iron and slag can be improved, and the recovery rate of metallic iron can be increased. The magnetized material obtained by magnetic separation again with a magnetic separator may be recovered as metallic iron, and the non-magnetically adhered material is mainly slag and contains almost no metallic iron. Recycle.

  As the separator, for example, a magnetic separator, a wind separator, a sieve b, or the like can be used.

  When the sieve b is used as the separator, it is preferable to collect the magnetic deposit obtained by magnetic separation using a magnetic separator after sieving using the sieve b as metallic iron. . The recovered metallic iron has a relatively low slag rate. On the other hand, non-magnetic deposits magnetically selected by a magnetic separator are mainly slag.

  In addition, after sieving using the sieve b, the sieve top is metallic iron having a large particle size, so it may be used as a product as it is or obtained by magnetic separation using a magnetic separator. The magnetic deposit may be recovered as metallic iron. Further, the sieve may be agglomerated into a briquette or the like by adding a binder or the like, if necessary. On the other hand, non-magnetic deposits magnetically selected by a magnetic separator are mainly slag.

  As the sieve b, for example, a sieve having an opening of 1 to 8 mm is preferably used.

  In this invention, you may operate further including the grinding | pulverization process which grind | pulverizes the magnetic deposit obtained by magnetic separation using the said magnetic separator using a grinder. You may grind | pulverize the ground material obtained at the said grinding | pulverization process again using a grinder. Further, the pulverized product obtained in the pulverization step may be magnetically separated using a magnetic separator, and the magnetized product may be recovered as metallic iron. The recovered magnetic deposit may be agglomerated into a briquette shape and used as an iron source, for example.

  As the pulverizer, for example, a ball mill, a rod mill, a cage mill, a rotor mill, or a roller mill can be used. When the object to be pulverized is small, it is difficult to apply an impact force and it is difficult to separate metallic iron and slag. Therefore, it is desirable to use a cage mill or a rotor mill. This is because cage mills and rotor mills can apply a strong impact even to small grains.

  Next, another method for producing metallic iron according to the present invention will be described.

In the present invention, the step of agglomerating the mixture containing the iron oxide-containing substance and the carbonaceous reducing agent (agglomeration step),
Charging the obtained agglomerate into a moving hearth type heating furnace and heating the molten agglomerate to form molten metal iron, molten slag, and reduced agglomerate (heating step); ,
A step of cooling the obtained mixture (cooling step);
A step of discharging the solid matter obtained by cooling from the moving hearth-type heating furnace (discharge step);
A sieving step of sieving using a sieve, metal slag discharged from the moving hearth heating furnace, slag, and floor covering material;
A process of collecting the metal iron by screening the screen obtained in the sieving process using a separator (hereinafter sometimes referred to as a second metal iron recovery process);
There is a feature in including.

  Among the above steps, the agglomeration step, heating step, cooling step, discharge step, and sieving step are the same as described above, so the description thereof will be omitted, and the second metal iron recovery step will be described in detail below. explain.

[Secondary metal iron recovery process]
In the second metallic iron recovery step, the sieving obtained in the sieving step is selected using a separator to recover metallic iron. On the other hand, since things other than metallic iron selected using a separator are mostly slag and hardly contain metallic iron, they may be used as raw materials for roadbed materials, soil conditioners, and the like.

  As the separator, for example, a magnetic separator may be used, and a magnetic deposit obtained by magnetic separation with the magnetic separator may be recovered as the metallic iron (hereinafter, sometimes referred to as a magnetic deposit recovery step).

  That is, in the magnetized product recovery step, the magnetized product is recovered by magnetically selecting the screen obtained in the sieving step using a magnetic separator. On the other hand, most of the non-magnetic deposits selected by magnetic separation are floor coverings and may be recycled.

In the present invention, the step of pulverizing the magnetic deposit recovered in the magnetic deposit recovery step using a pulverizer (hereinafter sometimes referred to as a pulverization step),
Screening the obtained pulverized product using a separator to recover metallic iron;
May further be included.

  The pulverizer may use an apparatus that applies at least one selected from the group consisting of impact force, friction force, and compression force to the magnetic article, and by applying impact force, friction force, or compression force, The slag can be separated from the magnetic deposit.

  As the pulverizer, for example, a ball mill, a rod mill, a cage mill, a rotor mill, or a roller mill can be used. A hammer mill may be used as the pulverizer.

  In the present invention, at least a part of the sieving obtained in the sieving step may be further operated by further pulverizing using a pulverizer. The pulverized material obtained in the step of pulverizing using a pulverizer may be magnetically selected using a magnetic separator and the magnetic deposit may be recovered. Moreover, you may grind | pulverize again the ground material obtained at the process grind | pulverized using a grinder using a grinder.

  The metallic iron selected and recovered using the separator or the magnetic deposit recovered by magnetic selection using the magnetic separator may be agglomerated into, for example, a briquette shape and used as an iron source.

  Next, the modification of the manufacturing method of metallic iron which concerns on this invention is demonstrated.

In the present invention,
Agglomerating a mixture comprising an iron oxide-containing substance and a carbonaceous reducing agent;
The obtained agglomerate and reduction aid (for example, flooring material) are charged into a moving hearth-type heating furnace and heated, and the agglomerate is melted to obtain molten metal iron, molten slag, and reduced agglomerate. Forming a composition;
Cooling the resulting mixture;
Discharging the solid matter obtained by cooling from the moving hearth-type heating furnace;
Dividing the discharge containing metal iron, slag, and floor covering material discharged from the moving hearth heating furnace into coarse and fine particles using a sieve a;
Selecting the obtained fine particles using a separator and recovering non-metallic iron (for example, flooring material);
May be operated.

In the present invention,
Agglomerating a mixture comprising an iron oxide-containing substance and a carbonaceous reducing agent;
Charging the obtained agglomerate into a moving hearth heating furnace and heating the molten agglomerate to form molten metal iron, molten slag, and reduced agglomerate;
Cooling the resulting mixture;
Discharging the solid matter obtained by cooling from the moving hearth-type heating furnace;
Dividing the discharge containing the metallic iron, slag, and floor covering material discharged from the moving hearth heating furnace into coarse particles 1 and fine particles 1 using a sieve a;
Crushing step of crushing the coarse particles 1;
Sieving the crushed material obtained in the crushing step into coarse particles 2 and fine particles 2,
Crushing the fine particles 1 and the fine particles 2;
May be operated.

  The fine particles 1 separated using the sieve a may be magnetically separated using a magnetic separator, and the obtained magnetic deposit may be mixed with the fine particles 2 and then pulverized.

  The fine particles 2 obtained by sieving the crushed material obtained in the crushing step are magnetically separated using a magnetic separator, and the obtained magnetic material is mixed with the fine particles 1 and then pulverized. Good.

In the present invention,
Agglomerating a mixture comprising an iron oxide-containing substance and a carbonaceous reducing agent;
Charging the obtained agglomerate into a moving hearth heating furnace and heating the molten agglomerate to form molten metal iron, molten slag, and reduced agglomerate;
Cooling the resulting mixture;
Discharging the solid matter obtained by cooling from the moving hearth-type heating furnace;
Dividing the discharge containing the metallic iron, slag, and floor covering material discharged from the moving hearth heating furnace into coarse particles 1 and fine particles 1 using a sieve a;
Crushing step of crushing the coarse particles 1;
Sieving the crushed material obtained in the crushing step into coarse particles 2 and fine particles 2,
Crushing the fine particles 1 and the fine particles 2;
Mixing the pulverized pulverized product and the coarse-grained product 2, and agglomerating the mixture;
May be operated.

  The fine particles 1 separated using the sieve a may be magnetically separated using a magnetic separator, and the obtained magnetic deposit may be mixed with the fine particles 2 and then pulverized.

  The fine particles 2 obtained by sieving the crushed material obtained in the crushing step are magnetically separated using a magnetic separator, and the obtained magnetic material is mixed with the fine particles 1 and then pulverized. Good.

  The pulverized pulverized product may be magnetically separated using a magnetic separator, and the obtained magnetic deposit may be agglomerated.

  Moreover, you may agglomerate the collection material collect | recovered at each process.

  As mentioned above, according to the manufacturing method of metallic iron which concerns on this invention, since crushing or grinding | pulverization is appropriately performed with respect to the discharge | emission from a moving hearth type heating furnace, metallic iron can be collect | recovered efficiently.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. Of course, it is possible to implement them, and they are all included in the technical scope of the present invention.

[Example 1]
In Example 1, when an agglomerate containing an iron oxide-containing substance and a carbonaceous reducing agent is heated in a mobile hearth-type heating furnace, the particle size and appearance of the exhaust discharged from the mobile hearth-type heating furnace I investigated the relationship.

  First, the mixture which mixed iron ore, coal, limestone, and the binder was agglomerated, and the agglomerate (pellet) was manufactured. A starch-based binder was used as the binder. For the production of the pellets, a pan pelletizer was used to produce spherical pellets having an average diameter of 19 mm, and the resulting spherical pellets were dried at 180 ° C. for 1 hour. The component composition of the pellets after drying is shown in Table 1 below.

  Next, the dried pellets were put into a rotary hearth furnace and heated at about 1450 ° C. for 10 minutes to melt the pellets to form molten metal iron and molten slag. Reduced agglomerates were also produced in the furnace. The obtained mixture was cooled by cooling means provided on the downstream side of the rotary hearth furnace, and the obtained solid was discharged from the rotary hearth furnace and further cooled.

  The discharged matter including metallic iron, slag, and floor covering material discharged from the rotary hearth furnace was sieved using a sieve having an opening of 2.5 mm.

  The sieving obtained by sieving was subjected to magnetic separation using a magnetic separator and sorted into magnetic and non-magnetic products. The magnetic deposit was collected as metallic iron. Non-magnetic products were mainly recycled floor coverings and were recycled.

  On the other hand, the sieve top obtained by sieving is metallic iron that can be recovered as a product, and was classified into four types based on the appearance shape. For each of the four types of metallic iron, the mass ratio with respect to the whole was calculated, and for each metallic iron, the mass ratio at each particle size was also calculated, and the results are shown in Table 2 below. Moreover, the component composition of 4 types of metallic iron was measured, and the result is shown in Table 3 below.

  From Table 2 and Table 3, it can be considered as follows.

(Metal iron A)
The external shape of the metallic iron A was granular. The mass ratio with respect to the whole metal iron A was 60.5%. As is apparent from Table 2, the metal iron A is mainly composed of particles having a particle size range of 5 to 15 mm. As is clear from Table 3, the metal iron A is a high-quality granular metal iron having a low slag content. .

(Metal iron B)
The external shape of the metallic iron B was flat, and was a shape in which a plurality of metallic irons were fixed. The mass ratio with respect to the whole metal iron B was 13.8%. As apparent from Table 2, this metal iron B was a metal iron having a particle size range as wide as 5 to 25.4 mm and a slag content slightly higher than that of the metal iron A, as is apparent from Table 3.

(Metal iron C)
The external shape of the metallic iron C was such that a plurality of large metallic irons were combined and a large amount of slag was interposed between them. The mass ratio with respect to the whole metal iron C was 10.6%. As is apparent from Table 2, the metal iron C is mainly composed of particles having a particle size range of 15 to 25.4 mm. As is clear from Table 3, the metal iron C has a higher slag content than the metal irons A and B. It was iron.

(Metal iron D)
The external shape of the metallic iron D was a mixture of outer shell-shaped metallic iron and spherical pellets. The mass ratio with respect to the whole metallic iron D was 15.1%. As is apparent from Table 2, the metallic iron D is mainly composed of particles having a particle size range of 15 to 19 mm. As is clear from Table 3, among the four types of metallic iron, the same as the metallic iron C. It was metallic iron with a large slag content. FIG. 1 shows a drawing-substituting photograph in which the appearance of metallic iron D is photographed.

  Next, the method for separating metallic iron and slag was examined for metallic iron D having the highest slag content and low quality.

  Metallic iron D was pulverized using a disk mill which is a kind of vibration mill. Specifically, 112 g of metallic iron D was put in a disk mill and pulverized for 30 seconds, followed by sieving using a sieve having an opening of 1 mm, and pulverizing the sieve further for 3 minutes.

  The particle size distribution of the pulverized product after pulverizing the sieve top for 3.5 minutes was examined, and the results are shown in Table 4 below. As is apparent from Table 4, coarse particles having a particle size range of 3.35 mm or more accounted for 46.92% of the whole. Since these coarse particles were metallic iron, they were hard to be pulverized any more.

Next, the pulverized product after pulverizing the sieve on the screen for 3.5 minutes was subjected to magnetic separation, and the mass ratio of the magnetized product and the non-magnetized product and the respective component compositions were measured. The measurement results are shown in Table 5 below. In Table 5, M.M. Fe means the amount of metallic iron. As is apparent from Table 5, 12.71% non-magnetic deposits could be separated by magnetic separation. The amount of slag (SiO ₂ + CaO + Al ₂ O ₃ ) contained in this non-magnetized product was 77%.

For the magnetic deposit, the metallization rate, the total amount of SiO ₂ and Al ₂ O ₃ , the slag rate, and the slag removal rate were calculated, and the results are shown in Table 6 below.
Metallization rate (%) = (M.Fe / T.Fe) × 100
Slag rate (%) = (SiO ₂ + Al ₂ O ₃ ) / T. Fe × 100
Slag removal rate (%) = [1− (amount of slag in the magnetic deposit after pulverization / amount of slag in the sample before pulverization)] × 100

The slag amount when calculating the slag removal rate means the sum of SiO ₂ + CaO + Al ₂ O ₃ .

  As is apparent from Table 6, the metallization rate was as high as 94.99%, the slag rate was reduced from 5.69% to 4.81%, and the slag removal rate was 56.63%. Therefore, it was found that even if the metal iron D having the highest slag content and low quality was produced by pulverization and magnetic selection, metal iron having a slag rate of about 4.81% could be produced.

[Example 2]
As shown in Example 1 above, the discharge containing metallic iron and slag discharged from the rotary hearth furnace is subjected to sieving, and then the top of the sieve is separated based on the external shape, and the slag content is reduced. Although it is reasonable to collect metallic iron by pulverizing the most metallic iron and magnetically selecting the obtained pulverized product, there are cases where an appropriate separation method cannot be selected industrially.

  Therefore, in Example 2, the mixed sample shown in Table 2 (on a sieve obtained by sieving the discharge containing metal iron and slag discharged from the rotary hearth furnace, A method for recovering metallic iron by crushing and magnetically separating the mixture was studied.

  A hammer mill capable of impact crushing was used for crushing the mixed sample. The number of rotations of the hammer was 1200 rpm, the opening of the rooster was 10 mm, 2.4 kg of the mixed sample was inserted, and the mixture was crushed for about 40 seconds. After repeating this twice, the particle size distribution was measured. The results are shown in Table 7 below. Table 7 below also shows the particle size distribution before crushing.

  As is clear from Table 7, the powder having a particle size of 5.66 mm or more was 90.7% before crushing, whereas the powder having a particle size of 5.66 mm or more was 66.8 after crushing. %, And the proportion of powder having a particle size of less than 5.66 mm is increasing.

  The pulverized powder was magnetically selected manually using a magnet, and the particle size distribution of the magnetic and non-magnetic products was examined. The result is shown in FIG. In FIG. 2, the particle size distribution of magnetic deposits is indicated by ■, and the particle size distribution of non-magnetic deposits is indicated by. Moreover, in FIG. 2, the particle size distribution in the powder before magnetic separation is shown together with ♦.

  As is clear from FIG. 2, it can be seen that the material refined by crushing is a non-magnetic product.

  Table 8 below shows the component composition of the magnetically adhered material and the non-magnetically adhered material. Table 8 also shows the component composition (calculated values) of the powder before magnetic separation after crushing. As apparent from Table 8 below, the non-magnetized material includes T.I. Although Fe was contained by 14.14%, most of the others were slag.

Regarding powders after crushing and before magnetic separation, and magnetic deposits, Fe, basicity (CaO / SiO ₂ ), slag ratio, T.P. C was calculated and shown in Table 9 below. The powder before magnetic separation after crushing had a slag ratio of 1.69%, whereas the magnetic deposit had a slag ratio reduced to 0.72%.

  FIG. 3 shows a drawing-substituting photograph of the magnetic deposit. As shown in FIG. 3, it can be seen that the surface of the particles is worn and the slag is separated and removed by crushing using a hammer mill.

[Example 3]
In Example 3, the sieving obtained by sieving the discharge containing metal iron and slag discharged from the rotary hearth furnace in Example 1 above using a sieve having a mesh opening of 2.5 mm. The method of recovering metallic iron from mine was examined.

  Table 10 below shows the particle size distribution of magnetic deposits obtained by magnetic separation using a magnetic separator for the sieves obtained by sieving using a sieve having a mesh opening of 2.5 mm. As is apparent from Table 10, it can be seen that in the magnetic deposit, the powder having a particle size of less than 1.0 mm accounts for 53.38% of the whole.

  In addition, Table 11 below shows the component composition of the magnetic deposit obtained by magnetic separation using a magnetic separator for the sieving obtained by sieving using a sieve having an opening of 2.5 mm. As is apparent from Table 11, the metallization rate is as high as 98.5% (= 73.87 / 74.97 × 100), but the slag rate is also 13.6% [= (8.43 + 1.73) / 74. .97 × 100], which is high.

  Therefore, the magnetized product obtained by magnetic separation using a magnetic separator is pulverized under the sieve obtained by sieving using a sieve having a mesh opening of 2.5 mm, and the obtained pulverized product is obtained. The metal iron was recovered again by magnetic separation. That is, a magnetized product obtained by magnetic separation using a magnetic separator with a sieve obtained by sieving using a sieve having a mesh opening of 2.5 mm is used as a cylindrical container having a diameter of 305 mm and a length of 305 mm. Then, 20 kg of steel balls and 1.4 kg of magnetic deposit (sample) were put and rotated at 68 rpm to pulverize the magnetic deposit. The grinding time was 0 minutes (no grinding), 5 minutes, 15 minutes, or 30 minutes. After pulverization, the obtained pulverized product was magnetically selected using a magnetic separator, and the particle size distributions of the magnetically adhered product and the non-magnetized product were examined. The results are shown in Table 12 below. Table 12 below also shows the ratios of magnetic deposits and non-magnetic deposits.

  Further, the slag rate was calculated for the magnetic deposits, the results are shown in Table 12, and the relationship between the grinding time and the slag rate is shown in FIG. As is apparent from Table 12 and FIG. 4, the magnetic deposit obtained when the pulverization time was 5 minutes had a slag ratio of 9.44%, whereas the pulverization time was 30 minutes. The obtained magnetic deposit had a slag ratio reduced to 5.89%. Therefore, it can be seen that as the pulverization time is increased, the slag rate can be reduced and high-quality metallic iron can be recovered. However, the decrease in the slag rate after pulverization time of 15 minutes was small, and the effect of pulverization was almost obtained in 15 minutes.

  FIG. 5 shows the particle size distributions of the magnetized product and the non-magnetized product. In FIG. 5, ♦ indicates the result of the magnetic material when the pulverization time is 0 minute, ◇ indicates the result of the non-magnetic material when the pulverization time is 0 minute, and ■ indicates the magnetic material when the pulverization time is 5 minutes As a result, □ is a result for a non-magnetized material when the pulverization time is 5 minutes, ▲ is a result for a magnetically adhered material when the pulverization time is 15 minutes, and △ is a non-magnetic material when the pulverization time is 15 minutes As a result, ● indicates the result for the magnetically adhered material when the pulverization time is 30 minutes, and ○ indicates the result for the non-magnetically adhered material when the pulverization time is 30 minutes.

  As apparent from Table 12 and FIG. 5, for magnetic products, the particle size distribution does not change much even when the pulverization time is increased, whereas for non-magnetic products, the particle size increases as the pulverization time increases. It can be seen that the amount of fine powder of 0.50 mm or less is increased.

[Example 4]
In Example 4, metal iron was manufactured in accordance with the metal iron manufacturing process shown in FIG. 6, and the crushing conditions in the crusher 34 and the type of crusher used suitably for the crusher 38 were examined.

  First, the manufacturing process of metallic iron will be described based on FIG. An agglomerate was produced by agglomerating a mixture containing an iron oxide-containing substance and a carbonaceous reducing agent. The obtained agglomerate was charged into a moving hearth-type heating furnace 31 and heated to melt the agglomerate to form molten metal iron, molten slag, and a reduced agglomerate. The obtained mixture was cooled, and the solid matter obtained by cooling was discharged from the moving hearth heating furnace 31. The discharge including metal iron, slag, and floor covering material discharged from the moving hearth heating furnace 31 was divided into coarse particles and fine particles using a sieve a32. The coarse particles (on the sieve) obtained with the sieve a32 were crushed using a crusher 34 that applied impact. The crushed material obtained by crushing was separated into two types using a separator 35.

  As the separator 35, a sieve was used. The sieve top obtained by sieving with a sieve was recovered as a product out of the system. On the other hand, the sieving obtained by sieving with a sieve was charged into a magnetic separator 37. The magnetic deposit obtained by magnetic separation with the magnetic separator 37 was charged into the pulverizer 38. The separator 35 and the magnetic separator 37 may be omitted.

  The pulverized material obtained by the pulverizer 38 was charged into a magnetic separator 39 and magnetically selected. The magnetic deposit obtained by magnetic separation was recovered from the path 48 as metallic iron. In addition, when the obtained magnetic deposit was further required to be separated from the slag, it was not collected as metal iron from the path 48 and charged into the pulverizer 40.

  The pulverized product obtained by the pulverizer 40 was charged into a magnetic separator 41 and magnetically selected. The magnetic deposit obtained by magnetic separation was recovered from the path 49 as metallic iron. In addition, when the obtained magnetic deposit further needs to be separated from the slag, it may not be recovered as metallic iron from the path 49, but may be charged again into the pulverizer to repeat pulverization and magnetic separation.

  The magnetic deposit obtained by magnetic separation with the magnetic separator 41 was loaded into the agglomerator 36 (for example, a briquette machine), agglomerated, and recovered as a product 51. The agglomerator 36 may be omitted. Further, FIG. 6 does not show a path for discharging the non-magnetized material selected by the magnetic separator 37, the magnetic separator 39, and the magnetic separator 41 to the outside of the system.

  Next, in this example, crushing conditions in the crusher 34 were examined.

  As the agglomerate, pellet A shown in Table 13 below was used. This agglomerate was charged into a moving hearth-type heating furnace 31 and reduced by heating. Heat reduction in the furnace was performed at 1400 to 1450 ° C.

  As the sieve a32, a sieve having an opening of 3.35 mm was used.

  As the crusher 34, a rod mill was used. A rod mill having an inner diameter of 0.5 m and a length of 0.9 m was used, and 460 kg of grinding medium rods were charged.

  The coarse particles charged in the rod mill were 50 kg, the crushing conditions were 40 rpm, and the crushing time was 3 minutes, 5 minutes, or 10 minutes. As a result, the slag rate of the crushed material obtained by crushing for 3 minutes is 10.2%, and the slag rate of the crushed material obtained by crushing for 5 minutes is 9.8%, and crushed for 10 minutes. The slag rate of the crushed material obtained in this manner was 9.6%. The slag ratio of the coarse particles charged in the rod mill was 28.0%.

The slag rate is the T.W. Ratio of the total mass of SiO ₂ and Al ₂ O _{3 to} the mass of Fe [(SiO ₂ + Al ₂ O ₃ ) / T. Fe × 100 (1)].

  From the above results, it was found that 3 minutes was sufficient for the crushing time in the crusher 34.

  Next, in this example, the type of pulverizer that is preferably used for the pulverizer 38 was also examined. The separator 35 and the magnetic separator 37 are omitted.

  As the pulverizer 38, a rod mill or a cage mill was used.

  When a rod mill was used, the grinding was performed once (the grinding time was 15 minutes). As a result, when a rod mill was used as the pulverizer 38, the slag rate was 13.8%.

  When a cage mill was used, pulverization was performed three times. That is, after pulverizing in the first pass, a part of the sample was collected, magnetically selected, and the slag ratio of the obtained magnetic deposit was measured. The remaining samples were crushed in the second pass. After pulverizing in the second pass, a part of the sample was collected, magnetically selected, and the slag ratio of the obtained magnetic deposit was measured. The remaining samples were pulverized in the third pass and then magnetically selected to measure the slag rate of the magnetic deposits. A cage mill having four rows and a diameter of the outermost row of 0.75 m was used, and the cage pins were crushed by colliding with the crushed material at a maximum speed of 40 m / sec. As a result, when a cage mill was used as the grinder 38, the first pass was 9.8%, the second pass was 7.9%, and the third pass was 6.5%. It was found that when a cage mill was used, the slag rate could be further reduced by repeating the pulverization.

  From the above results, it was found that the slag ratio contained in the pulverized product was relatively lower when the cage mill was used as the pulverizer 38 than when the rod mill was used.

[Example 5]
In Example 5, metallic iron is manufactured along the manufacturing process of metallic iron shown in FIG. The amount of Fe and the yield of Fe were examined.

  First, the manufacturing process of metallic iron shown in FIG.

  An agglomerate was produced by agglomerating a mixture containing an iron oxide-containing substance and a carbonaceous reducing agent. The obtained agglomerate was charged into a moving hearth-type heating furnace 31 and heated to melt the agglomerate to form molten metal iron, molten slag, and a reduced agglomerate. The obtained mixture was cooled, and the solid matter obtained by cooling was discharged from the moving hearth heating furnace 31.

  The discharge containing metal iron, slag, and floor covering material discharged from the moving hearth heating furnace 31 was divided into coarse particles and fine particles using a sieve a32. The fine particles (under the sieve) obtained by the sieve a32 were charged into the magnetic separator 42 and magnetically selected. The non-magnetized material obtained by magnetic separation was discharged out of the system from the path 43 and used as a floor covering material for a mobile hearth heating furnace. The magnetic deposit obtained by magnetic separation is T.I. Fe was 66.05%, and this was charged into the pulverizer 44 and pulverized.

  The pulverized material obtained by pulverization by the pulverizer 44 was separated into two types by the separator 45. In FIG. 7A, a magnetic separator 45 is used as the separator 45.

  In this example, the magnetic deposit selected by the magnetic separator 42 was pulverized using a ball mill as the pulverizer 44 shown in FIG. A ball mill having an inner diameter of 0.5 m and a length of 0.5 m was used. About 40 kg of the pulverized sample was charged, 180 kg of a grinding medium ball was charged, and the pulverization was performed at a rotation speed of 40 rpm and a pulverization time of 9 minutes. In addition, even if the grinding time is extended beyond 9 minutes, the T.O. Since it was difficult to increase the Fe ratio, the grinding time was set to 9 minutes.

  The TC contained in the pulverized product obtained by pulverization by the pulverizer 44. The amount of Fe and the yield rate of Fe were measured. As a result, T.W. Fe was 84.5%, and the yield rate of Fe was 96.3%.

  Next, the manufacturing process of metallic iron shown in FIG.7 (b) is demonstrated. The manufacturing process of metallic iron shown in FIG. 7B is a modification of the manufacturing process of metallic iron shown in FIG.

  The manufacturing process of metallic iron shown in FIG. 7B is a process of pulverizing the magnetic deposit obtained by the magnetic separator 45 with the pulverizing machine 46 in contrast to the manufacturing process of metallic iron shown in FIG. 7A is the same as FIG. 7A except that a step of magnetically selecting the pulverized material obtained by pulverization by the pulverizer 46 is added. The separator 45 (magnetic separator 45) may be omitted.

  In this example, a cage mill was used as the pulverizer 44 and the pulverizer 46 shown in FIG. That is, the magnetized material selected by the magnetic separator 42 was pulverized by the cage mill 44, a part of the sample was collected, and the rest was loaded into the cage mill 46 and pulverized.

  The grinding conditions in the cage mill are the same as the conditions shown in Example 5 above.

  A sample collected from the pulverized product obtained by pulverization with the cage mill 44 (that is, the first pulverization) was magnetically selected with a magnetic separator (not shown). TC contained in the obtained magnetic deposit. Fe was 85.8%, and the yield rate of Fe was 97.7%. In addition, a sample collected from the pulverized product obtained by pulverization (ie, the first pulverization) by the cage mill 44 is magnetically selected by a magnetic separator (not shown), and the obtained magnetic deposit is sieved with a sieve having an opening of 0.3 mm. The fine powder having a particle size of 0.3 mm or less was removed. The fine powder having a particle size of 0.3 mm or less contains a large amount of slag. Although the Fe yield was slightly reduced to 89.4% due to the small amount of Fe, T.W. The amount of Fe increased to 93.6%, and it became an iron product with higher use value.

  The pulverized material obtained by pulverization (that is, the second pulverization) by the cage mill 46 is magnetically selected by the magnetic separator 52, and the T.P. Fe was 88.7%, and the yield rate of Fe was 95.9%.

[Example 6]
In Example 6, metallic iron is manufactured according to the manufacturing process of metallic iron shown in FIG. The influence of Fe and Fe on the yield rate was examined.

  First, the manufacturing process of metallic iron will be described based on FIG.

  An agglomerate was produced by agglomerating a mixture containing an iron oxide-containing substance and a carbonaceous reducing agent. The obtained agglomerate was charged into a moving hearth-type heating furnace 31 and heated to melt the agglomerate to form molten metal iron, molten slag, and a reduced agglomerate. The obtained mixture was cooled, and the solid matter obtained by cooling was discharged from the moving hearth heating furnace 31. The discharged material including metallic iron, slag, and flooring material discharged from the moving hearth heating furnace 31 is divided into coarse particles and fine particles using a sieve a32. As the sieve a, a sieve having an opening of 3.35 mm was used.

  The coarse particles obtained on the sieve a32 (on the sieve) were collected as a product after magnetic separation. The fine particles (under the sieve) obtained by the sieve a32 were charged into the magnetic separator 42 and magnetically selected. The non-magnetized material obtained by magnetic separation was discharged out of the system from the path 43 and used as a floor covering material for a mobile hearth heating furnace. The magnetic deposit obtained by magnetic separation was charged into the pulverizer 44 and pulverized.

  The pulverized material obtained by pulverization by the pulverizer 44 was charged into a magnetic separator 55 and magnetically selected.

  The magnetic deposits selected by the magnetic separator 55 were separated into two types by the separator 45. In FIG. 8, the example which used the sieve 45 as the separator 45 was shown. The opening of the sieve is 0.3 mm.

  The sieve under the sieve 45 used as the separator 45 is discharged out of the system, and the sieve is charged into an agglomeration machine 53 (for example, a briquette machine) and agglomerated to form a briquette or the like. And recovered as a product 54.

  In addition, when giving priority to the iron yield rather than the high purity of iron in the product, the sieve 45 may be omitted, and the magnetized product of the magnetic separator 55 may be formed into a product.

  In this example, a ball mill or a cage mill was used as the pulverizer 44 shown in FIG.

  A ball mill having an inner diameter of 0.5 m and a length of 0.5 m was used. About 40 kg of the pulverized sample was charged, 180 kg of a grinding medium ball was charged, and the pulverization was performed at a rotation speed of 40 rpm and a pulverization time of 9 minutes. In addition, even if the grinding time is extended beyond 9 minutes, the T.O. Since it was difficult to increase the Fe ratio, the grinding time was set to 9 minutes.

  The TC contained in the pulverized product obtained by pulverization by the pulverizer 44. The amount of Fe and the yield rate of Fe were measured. As a result, T.W. Fe was 84.46%, and the yield rate of Fe was 96.27%.

  On the other hand, when the cage mill was used, the magnetic deposits selected by the magnetic separator 42 were pulverized by the cage mill 44. A sample collected after pulverization by the cage mill 44 (after the first pulverization) was magnetically selected by a magnetic separator 55. TC contained in the obtained magnetic deposit. Fe was 85.77%, and the yield rate of Fe was 97.7%.

  Moreover, the magnetic deposit obtained by magnetic separation with the magnetic separator 55 is sieved using a sieve having openings of 0.045 mm, 0.3 mm, 1.0 mm, and 3.35 mm, and is 0.045 mm or less, 0 .045 mm to 0.3 mm or less, 0.3 mm to 1.0 mm or less, 1.0 mm to 3.35 mm or less, classified into 5 levels, T. at each frequency. The amount of Fe was calculated. As a result, the T.I. The amount of Fe is 32.30%, T.D. The amount of Fe is 45.27%, T.D. The amount of Fe was 86.82%, T.D. in powders of more than 1.0 mm and 3.35 mm or less. The amount of Fe is 96.18%, T.D. The amount of Fe was 96.20%. As is clear from this result, the finer powder has more slag content. It can be seen that the amount of Fe is small. Therefore, when the fine powder is removed, the yield of Fe is somewhat reduced, but the effect is small, while the average T.I. Since Fe can be increased, it is effective. In addition, although the sieve was used for the selection of fine powder here, for example, when a large amount of fine powder having a particle size of 2 mm or less is separated, it is suitable to use a wind separator instead of the sieve.

  A sample collected after being pulverized by the cage mill 44 (after the first pulverization) was magnetically selected by a magnetic separator 55, and the obtained magnetic deposit was passed through a sieve 45 having an opening of 0.3 mm so that the particle size was 0. Fine powder of 3 mm or less was removed. The fine powder having a particle size of 0.3 mm or less contains a large amount of slag. Although the Fe yield was slightly reduced to 89.4% due to the small amount of Fe, T.W. The amount of Fe increased to 93.6%, and it became an iron product with higher use value.

  In addition, after the first pass pulverization by the cage mill, a part is returned again to the cage mill, and after the second pass pulverization, the pulverized material is loaded into the magnetic separator 55 and magnetically selected. Sorted into kimono and non-magnetic kimono. The non-magnetized product obtained by sorting was sieved with a separator 25. T. contained on the sieve. The amount of Fe and the yield rate of Fe were calculated. As a result, T.W. The amount of Fe was 88.72%, and the yield rate of Fe was 95.9%.

  From the above results, the T.V. It can be seen that the amount of Te and the yield rate of Fe change.

[Example 7]
In Example 7, all steps in the method for producing metallic iron according to the present invention will be described with reference to FIG.

  An agglomerate was produced by agglomerating a mixture containing an iron oxide-containing substance and a carbonaceous reducing agent. The obtained agglomerate was charged into a moving hearth-type heating furnace 31 and heated to melt the agglomerate to form molten metal iron, molten slag, and a reduced agglomerate. The obtained mixture was cooled, and the solid matter obtained by cooling was discharged from the moving hearth heating furnace 31.

  The discharge containing metal iron, slag, and floor covering material discharged from the moving hearth heating furnace 31 was divided into coarse particles and fine particles using a sieve a32. The coarse particles obtained on the sieve a32 (on the sieve) were magnetically selected using a magnetic separator 33. The non-magnetized material obtained by magnetic separation was discharged out of the system through a route not shown. The magnetic deposit obtained by magnetic separation was crushed using a crusher 34 that applied impact.

  The crushed material obtained by crushing was separated into two types using a separator 35. As the separator 35, for example, a magnetic separator, a wind separator, a sieve b, or the like can be used.

  When a magnetic separator is used as the separator 35, the magnetic material obtained by magnetic separation may be charged into the agglomerator 36 and the non-magnetic material may be charged into the magnetic separator 37. In addition, when using a magnetic separator as the separator 35, it is preferable to set a magnetic force smaller than the magnetic separator 37 used at a lower process.

  When a wind separator is used as the separator 35, coarse particles or large specific gravity obtained by wind selection may be charged into the agglomerator 36, and fine particles may be charged into the magnetic separator 37. .

  When the sieve b is used as the separator 35, the sieve top obtained by sieving may be charged into the agglomerator 36 and the sieve below may be charged into the magnetic separator 37.

  The non-magnetized material obtained by magnetic separation with the magnetic separator 37 may be discharged out of the system, and the magnetized material may be charged into the agglomerator 36. In addition, when the obtained magnetic deposit needs to be further separated from the slag, the magnetic deposit may be charged into the pulverizer 38.

  The pulverized material obtained by the pulverizer 38 may be charged into the magnetic separator 39 and magnetically selected. The non-magnetized material obtained by magnetic separation may be discharged out of the system, and the magnetized material may be charged into the agglomerator 36. In addition, what is necessary is just to insert a magnetic attachment into the grinder 40, when the obtained magnetic attachment needs further isolation | separation from slag.

  The pulverized material obtained by the pulverizer 40 may be charged into the magnetic separator 41 and magnetically selected. The magnetized material obtained by magnetic separation is inserted into the agglomerator 36, and the non-magnetized material may be discharged out of the system from a path not shown.

  In addition, although the example which provided the magnetic separator 37, the magnetic separator 39, and the magnetic separator 41 separately was shown in FIG. 9, you may substitute these with one magnetic separator. Moreover, although the example which provided the grinder 38 and the grinder 40 separately was shown in FIG. 9, you may substitute for these with one grinder. Further, the number of magnetic separation and pulverization is not limited to the number shown in FIG.

  Next, it returns to the sieve a and demonstrates.

  The fine particles (under the sieve) obtained by the sieve a32 were charged into the magnetic separator 42 and magnetically selected. Instead of the magnetic separator 42, a wind separator may be used.

  The non-magnetized material obtained by magnetic separation may be discharged out of the system from the path 43 and reused, for example, as a flooring material. The magnetic deposit obtained by magnetic separation may be charged from the magnetic separator 42 to the agglomerator 36, or may be charged from the magnetic separator 42 to the pulverizer 44 and pulverized.

  The pulverized material obtained by pulverization by the pulverizer 44 was separated into two types using a separator 45. As the separator 45, for example, a magnetic separator or a wind separator can be used. When a magnetic separator is used as the separator 45, the magnetic deposit obtained by magnetic separation may be inserted into the pulverizer 46, and the non-magnetic deposit may be discharged out of the system from the path 47. When a wind separator is used as the separator 45, the coarse particles or large specific gravity obtained by wind selection may be charged into the pulverizer 46, and the fine particles may be discharged out of the system from the path 47. In addition, as the separator 45, you may provide both a magnetic separator and a wind selector.

  The pulverized material obtained by pulverization by the pulverizer 46 is charged into a magnetic separator 56 and magnetically separated to remove non-magnetically adhered materials. The magnetic deposit obtained by magnetic separation may be charged into the agglomerator 36 and formed into a briquette or the like and used as an iron source.

  The pulverizer 44 and the pulverizer 46 may be provided with different types of pulverizers. In the case where the slag is easily separated, the pulverizer 46 may be omitted and the number of pulverizations may be set to one.

Claims (25)

Agglomerating a mixture comprising an iron oxide-containing substance and a carbonaceous reducing agent;
Charging the obtained agglomerate into a moving hearth heating furnace and heating the molten agglomerate to form molten metal iron, molten slag, and reduced agglomerate;
Cooling the resulting mixture;
Discharging the solid matter obtained by cooling from the moving hearth-type heating furnace;
Crushing the discharge containing metallic iron, slag, and flooring material discharged from the moving hearth furnace using a crusher;
Screening the obtained crushed material using a separator and recovering metallic iron;
The manufacturing method of metallic iron characterized by including. Dividing the discharge containing the metallic iron, slag, and flooring material discharged from the moving hearth-type heating furnace into a sieve top and a sieve using a sieve a;
Crushing the obtained sieve using a crusher;
Screening the obtained crushed material using a separator and recovering metallic iron;
The manufacturing method of Claim 1 containing this.   The manufacturing method according to claim 1 or 2, wherein a hammer mill, a cage mill, a rotor mill, a ball mill, a roller mill or a rod mill is used as the crusher.   The said sieve top is a manufacturing method of Claim 2 or 3 containing 95% or less of iron in conversion of iron content.   The manufacturing method according to any one of claims 2 to 4, wherein, prior to crushing the top of the sieve, the top of the sieve is magnetized using a magnetic separator to collect the magnetic deposit, and the collected magnetic deposit is crushed.   The manufacturing method according to claim 1, wherein a magnetic separator is used as the separator.   The manufacturing method according to claim 1, wherein a wind separator is used as the separator.   The production method according to claim 1, wherein a sieve b is used as the separator.   The method according to claim 8, wherein after sieving using the sieve b, the bottom of the sieve is magnetically separated using a magnetic separator to recover metallic iron.   The manufacturing method according to claim 8 or 9, wherein a sieve having an opening of 1 to 8 mm is used as the sieve b.   The manufacturing method according to claim 6 or 9, further comprising a pulverizing step of pulverizing a magnetic deposit obtained by magnetic separation using the magnetic separator using a pulverizer.   The manufacturing method according to claim 11, wherein the pulverized product obtained in the pulverization step is pulverized again using a pulverizer.   The manufacturing method according to claim 11, wherein the pulverized product obtained in the pulverizing step is magnetically selected using a magnetic separator and the magnetic deposit is recovered.   The manufacturing method according to claim 13, wherein the collected magnetic deposit is agglomerated.   The manufacturing method according to claim 11, wherein a ball mill, a rod mill, a cage mill, a rotor mill, or a roller mill is used as the pulverizer. Agglomerating a mixture comprising an iron oxide-containing substance and a carbonaceous reducing agent;
Charging the obtained agglomerate into a moving hearth heating furnace and heating the molten agglomerate to form molten metal iron, molten slag, and reduced agglomerate;
Cooling the resulting mixture;
Discharging the solid matter obtained by cooling from the moving hearth-type heating furnace;
A sieving step of sieving using the sieve a, the metal iron, slag, and floor covering material discharged from the moving hearth heating furnace,
Screening the sieving obtained in the sieving step using a separator and recovering metallic iron; and
The manufacturing method of metallic iron characterized by including.   The manufacturing method according to claim 16, wherein a magnetic separator is used as the separator, and a magnetic deposit obtained by magnetic separation with the magnetic separator is recovered as the metallic iron. A step of pulverizing the recovered magnetic deposit using a pulverizer;
Screening the obtained pulverized product using a separator to recover metallic iron;
The manufacturing method of Claim 17 containing.   The manufacturing method of Claim 16 which further includes the process of grind | pulverizing at least one part of the sieving obtained by the said sieving process using a grinder.   The manufacturing method according to claim 19, wherein the pulverized material obtained in the step of pulverizing using the pulverizer is magnetically selected using a magnetic separator, and the obtained magnetic deposit is recovered.   The manufacturing method of Claim 19 which grind | pulverizes again the ground material obtained at the process grind | pulverized using the said grinder using a grinder again.   The manufacturing method according to claim 18 or 20, wherein the recovered metallic iron or the recovered magnetic deposit is agglomerated.   The manufacturing method according to any one of claims 18 to 22, wherein as the pulverizer, one that adds at least one selected from the group consisting of an impact force, a frictional force, and a compressive force is used.   The manufacturing method according to claim 23, wherein a ball mill, a rod mill, a cage mill, a rotor mill, or a roller mill is used as the pulverizer.   The manufacturing method according to claim 2 or 16, wherein a sieve having an opening of 2 to 8 mm is used as the sieve a.