WO2013161653A1 - Metal iron-containing sintered body - Google Patents

Description

Metallic iron-containing sintered body

The present invention relates to a sintered metal-containing sintered body obtained by heating an agglomerate containing an iron oxide-containing substance and a carbonaceous material.

As a method for producing reduced iron (metallic iron) from iron oxide-containing materials such as iron ore, for example, (1) calcined pellets containing iron ore are heated to about 1000 ° C. in a shaft furnace and calcined pellets by reducing gas A method of reducing iron oxide contained in
(2) The agglomerate obtained by mixing and agglomerating iron ore and carbonaceous material (solid reducing material) is supplied to a moving hearth furnace (rotary hearth) and heated at about 1300 ° C. A method of reducing the contained iron oxide (sometimes called FASTMET method),
(3) After supplying and agglomerating agglomerates of iron ore and carbonaceous material (solid reducing material) to the moving hearth furnace and reducing the iron oxide contained in the agglomerates In addition, a method of further heating to about 1450 ° C. to melt the reduced iron and separating it into reduced iron and slag due to a difference in surface tension or the like (sometimes referred to as ITmk3 method),
Etc. are known. Regarding such a method for producing reduced iron, for example, the techniques of Patent Documents 1 to 4 are known.

Regarding the method of (1), for example, Patent Document 1 discloses that iron ore is directly reduced and pulverized, and after separating iron and gangue, both are further pulverized and iron is recovered from each. Are listed. In addition, CO gas or H ₂ gas can be used as the reducing gas, the heating temperature should be 700 to 1200 ° C., the crushing can be performed using a roll crusher or the like that can extend metallic iron into pieces, iron and gangue In the separation, it is described that separation by a 20-mesh sieve or magnetic separation is performed in combination.

Regarding the method of (2) above, for example, in Patent Document 2, a mixture containing an iron raw material and coal is heated and reduced in a high-temperature atmosphere, and the obtained reduced iron is pulverized, It is described that the particle size is selected on the basis of the particle size. 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. Reduced iron particles having an average particle size of 100 μm or less are separated into strong magnetic particles containing a large amount of iron and weak magnetic particles having a small amount of iron by magnetic force, and reduced iron particles exceeding the predetermined particle size subjected to particle size selection, The ferromagnetic deposit particles are used as reduced iron. On the other hand, weakly magnetized particles are low in iron and contain a lot of slag, so they are reused as cement or asphalt. Therefore, in the said patent document 2, it does not consider at all about isolate | separating slag from the weak magnetic deposit particle | grains with little iron content, collect | recovering iron content, and utilizing as an iron source.

Regarding the method (3), for example, the techniques of Patent Document 3 and Patent Document 4 are known. Among these, in Patent Document 3, a carbon-containing pellet composed of a plurality of types of dust and carbon material is produced, and this is subjected to reduction treatment at a temperature of 1250 to 1350 ° C. in a rotary hearth-type firing furnace, The dust inside the pellets is reduced by the carbonaceous material, and the metallic iron particles aggregated by the intra-granular mass transfer are metallically separated from the low melting point slag containing FeO generated from the dust gangue using the action of metallic separation. A method for producing high-grade reduced iron from iron-making dust that extracts iron particles to produce high-grade granular reduced iron is described. This document describes that reduced iron obtained in a rotary hearth-type firing furnace is sieved using a screen, and reduced iron having a diameter of 5 mm or more is recovered as a product.

In Patent Document 4, a carbon-containing pellet composed of iron ore and a carbonaceous material is manufactured, reduced in a rotary hearth-type firing furnace at a temperature of 1250 to 1350 ° C., and then the furnace temperature is set to 1400 to A method is described in which high temperature granular metallic iron is obtained by raising the temperature to 1500 ° C., melting, and aggregating metallic iron.

However, in Patent Documents 3 and 4, metal iron and slag are separated by completely melting reduced iron (metal iron) obtained by reduction, and the metal obtained in a state where the metal iron is not completely melted. No consideration is given to separability when a sintered body in which iron and slag are mixed is separated into metallic iron and slag. In particular, when the amount of slag increases, the cohesiveness of metallic iron deteriorates and the separability of metallic iron and slag deteriorates.

US Pat. No. 6,048,382 JP 2002-363624 A JP-A-10-147806 JP 2009-91664 A Japanese Patent Laid-Open No. 9-256017

Regarding the above methods (2) and (3), the present applicant has proposed a method for producing metallic iron in Patent Document 5. In this production method, a metallic iron skin is generated and grown by heat reduction, and the reduction is advanced until iron oxide is substantially absent inside, and aggregates of the generated slag are formed inside. In this technique, an aggregate of slag is formed inside the metal iron shell, and the aggregate is in close contact with the metal iron shell, and the metal iron shell and slag may not be sufficiently separated.

This invention was made paying attention to the above situations, and the object was obtained by heating an agglomerate containing an iron oxide-containing substance and a carbonaceous material, and a mixture of metallic iron and slag. An object of the present invention is to provide a metal iron-containing sintered body having good separability when separating the metal iron-containing sintered body into metal iron and slag.

The metallic iron-containing sintered body according to the present invention that has solved the above problems includes a mixture containing granular metallic iron and slag inside an outer shell containing metallic iron and slag, and has a temperature of 1000. It has a gist in that it is below ℃. In the present specification, the metallic iron contained in the outer shell constituting the metal-containing sintered body and the granular metallic iron contained in the mixture contained inside the outer shell are simply referred to as “ Sometimes referred to as “metallic iron” or “(granular) metallic iron”.

In the outer shell, metallic iron may be formed in a network shape. The granular metallic iron contained in the mixture preferably has an average particle size of 3 mm or less (excluding 0 mm). The metallic iron-containing sintered body has a basicity [CaO / SiO ₂ ] of slag determined from the amount of CaO and the amount of SiO ₂ when the average component composition of the slag contained in the metallic iron-containing sintered body is measured. It is preferable that it is 0.2 or more and less than 0.9.

When the average component composition of the granular metallic iron contained in the metallic iron-containing sintered body is measured, if the ratio of S amount to Fe amount (S / Fe) is 0.0017 or less (not including 0) Good. When the average component composition of the metallic iron contained in the metallic iron-containing sintered body is measured, the C content is preferably 0.3 to 2.5% by mass. When the average component composition of the granular metallic iron contained in the metallic iron-containing sintered body is measured, the C content is preferably 1.5 to 5% by mass.

Since the metallic iron-containing sintered body of the present invention is configured to include an outer shell containing metallic iron and slag and a mixture containing granular metallic iron and slag inside the outer shell, the outer shell, and Both the inner mixture can be pulverized relatively easily. Therefore, if the obtained pulverized product is separated by magnetic separation, it can be easily separated and recovered by using metallic iron as a magnetic deposit and slag as a non-magnetic deposit.

FIG. 1 is a drawing-substituting photograph in which a longitudinal section of a sintered body obtained by heating at 1300 ° C. for 18 minutes is photographed. FIG. 2 is a drawing-substituting photograph in which a part of the outer shell is enlarged in the longitudinal section of the sintered body shown in FIG. FIG. 3 shows the basicity (CaO / SiO ₂ ) of the magnetic deposit and the SiO ₂ / T. It is a graph which shows the relationship with the value of Fe. FIG. 4 shows the SiO ₂ / T. The value of Fe and the S / T. It is a graph which shows the relationship with the value of Fe. FIG. 5 shows the SiO ₂ / T. It is a graph which shows the relationship between the value of Fe, and the amount of C of a magnetic deposit. FIG. 6 shows the melting temperature of the CaO—SiO ₂ —Al ₂ O ₃ ternary oxide from the heating temperature T in the electric furnace. 4 is a graph showing a relationship between a value obtained by subtracting T (TLT) and a non-magnetization rate. FIG. 7 is a graph showing the relationship between the melting amount of the CaO—SiO ₂ —Al ₂ O ₃ ternary oxide at a temperature lower than the heating temperature T by 100 ° C. (T-100 ° C.) and the non-magnetization rate. .

The present inventors heated an agglomerate containing an iron oxide-containing substance and a carbonaceous material, and then pulverized, and magnetically separated metallic iron and slag produced as a by-product when the metallic iron was produced. In collecting each of iron and slag, intensive investigations have been made in order to improve the separability between metallic iron and slag. As a result, an agglomerate containing an iron oxide-containing substance and a carbonaceous material is heated in a heating furnace to produce a metallic iron-containing sintered body in which metallic iron and slag are mixed. If the outer shell containing iron and slag and a mixture containing granular metallic iron and slag are included inside the outer shell, the separation between (granular) metallic iron and slag during magnetic separation can be improved. The present invention has been completed. That is, the metallic iron-containing sintered body of the present invention is characterized in that a mixture containing granular metallic iron and slag is included inside the outer shell containing metallic iron and slag, and the temperature is 1000 ° C. or less. Have.

Since the metallic iron-containing sintered body is covered with the outer shell, the metallic iron-containing sintered body obtained by heating can be taken out from the heating furnace without collapsing. Therefore, almost no metallic iron or slag remains on the hearth of the heating furnace, so that the yield of metallic iron can be improved. Further, it is possible to suppress the iron heart and slag from remaining on the hearth and damaging the hearth.

The outer shell contains metallic iron and slag. By including metallic iron and slag, the strength of the outer shell becomes smaller than that composed only of metallic iron, so that it becomes easy to grind and separability from slag is improved.

The inside of the outer shell contains a mixture containing granular metallic iron and slag. By making the mixture encapsulated in the outer shell into a mixture containing granular metallic iron and slag, the mixture can be easily pulverized. Therefore, if the pulverized product is magnetically separated, (granular) metallic iron can be separated and recovered as a magnetized product and slag as a non-magnetized product. Therefore, according to the present invention, since the slag is hardly mixed in the (granular) metallic iron, the purity of the (granular) metallic iron can be increased.

The temperature of the sintered metal-containing sintered body of the present invention is 1000 ° C. or lower. The temperature of 1000 ° C. or less means that the agglomerate is cooled in a heating furnace and then cooled. That is, the metallic iron-containing sintered body of the present invention can be obtained by heating an agglomerate containing an iron oxide-containing substance and a carbonaceous material in a heating furnace. As will be described later, in the heating furnace, 1200 to 1450 ° C. Heated to a degree. Thereafter, as a result of cooling, it means that the mixture is contained in the outer shell in a cooled state.

On the other hand, in Patent Documents 3 to 5, the agglomerate containing the iron oxide-containing substance and the carbonaceous material is heated in the heating furnace, and therefore, in the middle of the heating, the structure including the mixture inside the outer shell There is a possibility that. However, since the heating temperature described in these documents is relatively high, the sintered body finally obtained is considered that reduction and aggregation of metallic iron are sufficiently advanced even inside the outer shell. . Therefore, in the sintered body obtained by cooling after heating, there is no granular metallic iron inside the outer shell, and the reduced metallic iron is considered to constitute the outer shell. Therefore, in these documents, it is thought that the separability between metallic iron and slag is poor.

It is preferable that the granular metallic iron contained in the mixture contained inside the outer shell has an average particle size of 3 mm or less. By making the average particle diameter of the granular metallic iron 3 mm or less, the separability between the granular metallic iron and the slag when magnetically separated can be improved. Although the minimum of the particle size of the said granular metallic iron is not specifically limited, The minimum value which can be observed is about 0.08 mm.

In the outer shell, metallic iron is formed in a network shape (mesh shape) and there are voids like a porous material. And in the said outer shell, the slag exists in the network-like structure | tissue which the metal particle connected, and at least one part of the clearance gap between the structure | tissues. Therefore, the strength of the outer shell is smaller than that of only metallic iron, and it is easy to grind.

However, when the reduction at a relatively low temperature or the heating time is short, the metallic iron in the outer shell portion does not bind greatly, so that it is difficult to completely separate the metallic iron and the slag even if pulverized. is there.

The metal iron-containing sintered body needs to be entirely covered with the outer shell so as not to leak the internal mixture contained in the outer shell. The strength of the sintered iron-containing sintered body may be in a range that can maintain the shape when discharged from a heating furnace with a discharger or the like, and the lower limit of the cross-sectional area ratio of the outer shell portion is the center of the sintered metal-containing sintered body In the cross section cut so as to include, approximately 50 area% or more is sufficient.

When the average component composition of the slag contained in the metallic iron-containing sintered body is measured, the basic property of the slag obtained from the CaO amount and the SiO ₂ amount [CaO / SiO _{2] is obtained.} ] Is preferably 0.2 or more and less than 0.9. By adjusting the component composition of the agglomerate so that the basicity satisfies this range, the internal metallic iron contained in the outer shell can be granulated, and the separability between granular metallic iron and slag can be improved. Can be improved. That is, in order to granulate the metallic iron contained inside the outer shell, it is necessary to melt the gangue contained in the agglomerate to form slag and to aggregate the slag. In order to quickly melt the gangue contained in the agglomerate, the composition of the gangue may be adjusted so that the melting point of the gangue is lowered. Then, what is necessary is just to adjust the component composition of the said agglomerate so that the basicity of the said slag byproduced at the time of heating may satisfy the said range. The upper limit of the basicity is more preferably 0.8 or less, still more preferably 0.7 or less, and particularly preferably 0.6 or less.

The average component composition of slag contained in the metal iron-containing sintered body is the average component composition of slag contained in the outer shell and slag contained in the internal mixture contained in the outer shell. I mean.

When the average component composition of the granular metallic iron contained in the metallic iron-containing sintered body of the metallic iron-containing sintered body of the present invention is measured, the ratio of S amount to Fe amount (S / Fe) is 0. .0017 or less. The S / Fe ratio is preferably 0.0015 or less. The granular metallic iron mentioned here means that the metallic iron-containing sintered body obtained by reduction is separated into an outer shell and a mixture contained inside the outer shell, and this mixture is pulverized and magnetically selected. The obtained magnetic deposit is said. That is, the metallic iron-containing sintered body of the present invention is separated into an outer shell and a mixture contained inside the outer shell, and, as described above, pulverized and magnetically separated to separate granular metallic iron and Good separation into slag. At this time, as demonstrated in the examples described later, as the ratio of the SiO ₂ amount to the Fe amount decreases, the ratio of the S amount to the Fe amount tends to decrease proportionally. This tendency means that a large amount of S exists in the slag and hardly exists in the granular metallic iron. Therefore, if the Fe and slag can be separated well, the ratio of the S amount to the Fe amount can be reduced. Further, as demonstrated in the examples described later, when the agglomerate is heated at a high temperature, S is bound to Fe, so the ratio of the S amount to the Fe amount increases. Accordingly, by heating the agglomerate at a low temperature, the ratio of the S amount to the Fe amount can be reduced.

The metallic iron-containing sintered body of the present invention has a C content of 0.00 when the average component composition of the metallic iron (metallic iron constituting the outer shell) contained in the metallic iron-containing sintered body is measured. The content is preferably 3 to 2.5% by mass, more preferably 0.6 to 2.0% by mass. Further, when the average component composition of the granular metallic iron (inside) contained in the sintered metal-containing sintered body is measured, the C content is preferably 1.5 to 5% by mass, more preferably 1. 7 to 4.5% by mass. If the amount of C satisfies this range, when the agglomerate is heated, the reduction rate of iron oxide contained in the agglomerate is improved. That is, the fixed carbon contained in the carbonaceous material embedded in the agglomerate is used for the reduction reaction of iron oxide, gasifies by reacting with the atmospheric gas, and the remaining C is in the metallic iron and granular metallic iron. To remain. At this time, C consumed by the reduction reaction of iron oxide becomes CO ₂ gas, but the generated CO ₂ gas is reduced by surrounding C to become CO gas. The generated CO gas reduces iron oxide. Therefore, the charcoal blended in the agglomerate so that a certain amount of C remains in the (granular) metallic iron obtained by heating (the total of the metallic iron contained in the outer shell and the granular metallic iron contained in the mixture). By adjusting the amount of material, the reduction of iron oxide contained in the agglomerate can be promoted. Moreover, since it is necessary to carburize C in metallic iron in order to spheroidize the metallic iron obtained by heat reduction, it is necessary for C to remain to some extent to produce granular metallic iron. .

In addition, the average component composition of the metal iron contained in the metal iron-containing sintered body means the average component composition of the metal iron contained in the outer shell, and is included in the metal iron-containing sintered body. The average component composition of the granular metallic iron means the average component composition of metallic iron contained in the mixture included in the outer shell.

The method for producing the metallic iron-containing sintered body of the present invention is not particularly limited, but the following method can be suitably employed.

The metallic iron-containing sintered body of the present invention can be suitably produced by heating an agglomerate containing an iron oxide-containing substance and a carbonaceous material so that a part thereof melts and a whole part does not melt. It is effective to further add a melting point adjusting agent to the mixture of the iron oxide-containing substance and the carbonaceous material. That is, in producing a metallic iron-containing sintered body in which metallic iron and slag are mixed in the present invention, a step of agglomerating a raw material mixture in which a melting point regulator is further blended with an iron oxide-containing substance and a carbonaceous material (hereinafter referred to as “aggregation”) The agglomeration step) and the step of heating so that a part of the obtained agglomerate melts and reducing the iron oxide contained in the agglomerate (hereinafter referred to as the heating step) in this order. It is effective to include in. In this heating step, the iron oxide contained in the agglomerate is heated by heating the agglomerate at a temperature equal to or higher than a temperature at which a part of the obtained agglomerate melts and less than a temperature at which it completely melts. It is preferable to carry out reduction. Each step will be described in detail below.

[Agglomeration process]
In the agglomeration process of the present invention, it is preferable to further blend a melting point adjusting agent with the iron oxide-containing substance and the carbonaceous material.

The above-mentioned melting point modifier means a substance that affects the melting point of components (particularly gangue) other than iron contained in the agglomerate, excluding substances that affect the melting point of iron. That is, by blending a melting point modifier as the raw material mixture, the melting point of components (particularly gangue) other than iron oxide contained in the agglomerate is affected, and for example, the melting point can be lowered. Thereby, the gangue is promoted to melt and forms 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. Thus, in this invention, the metallic iron containing sintered compact in which metallic iron and slag were mixed is obtained.

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. Further, as a part of the melting point adjusting agent, a low-grade iron oxide-containing substance containing these melting point adjusting components can be used.

In the present invention, the amount of CaO supply substance to be blended in the agglomerate is adjusted, and the basicity of slag (CaO / C) obtained from the CaO amount (% by mass) and the SiO ₂ amount (% by mass) in the agglomerate. SiO ₂₎ of 0.2 or more, it is preferable to adjust such that the range of less than 0.9. By controlling the basicity of the slag within this range, the melting point of the gangue (particularly CaO—SiO ₂ —Al ₂ O ₃ ternary oxide) contained in the agglomerate can be lowered. Therefore, the gangue can be melted even at a relatively low temperature, and the amount of melting in the agglomerate can be increased. The basicity of the slag is more preferably 0.3 or more, and still more preferably 0.35 or more. The basicity of the slag is more preferably 0.8 or less, and still more preferably 0.5 or less.

As the iron oxide-containing substance, for example, iron ore, iron sand, iron-making dust, non-ferrous refining residue, iron-making waste, and the like can be used.

In the present invention, it is possible to use low-grade iron ore that has not been conventionally used. For example, low-grade iron ore that contains SiO ₂ more than 6 wt% (hereinafter sometimes referred to as high SiO ₂ content iron ore.) Was prepared, and the high SiO ₂ content of iron ore and carbonaceous material and the melting point adjusting The raw material mixture containing the agent may be agglomerated to produce an agglomerate. By heating the agglomerate containing low-grade iron ore, carbonaceous material, and a melting point modifier, the ash content in the carbonaceous material and the melting point modifier are used as a flux to partially produce molten slag in the agglomerate. The agglomeration of metallic iron can be achieved, and metallic iron can be produced in a short time. That is, when heating an agglomerate containing low-grade iron ore, carbonaceous material, and a melting point modifier as in the present invention, the FeO remains even if FeO—SiO ₂ -based molten slag is generated in the agglomerate. It reacts with the carbon contained in the nearby carbonaceous material, and metallic iron is rapidly produced. Therefore, in the agglomerate, metallic iron and slag such as SiO ₂ are generated separately, so even if metallic iron and slag are mixed, the slag is easily crushed by crushing these, and metal It can be separated into iron and slag. Therefore, conventionally, the high SiO ₂ content iron ore has not been used as a commercial iron ore because of the high content of gangue, but according to the present invention, the high SiO ₂ content iron ore is used as an iron source. be able to.

As the high SiO ₂ content iron ore, for example, it can be used iron ores containing SiO ₂ or 6 weight%, as a gangue non SiO _2, usually contain Al ₂ O ₃ or the like Yes. In the present invention, high-grade iron ore having a SiO ₂ content of less than 6% by mass can also be used.

For example, coal or coke can be used as the carbon material. The said carbon material should just contain the fixed carbon of the quantity which can reduce the iron oxide contained in the said iron oxide containing substance. Specifically, it is sufficient that the iron oxide contained in the iron oxide-containing substance is excessively contained in the range of 0 to 5% by mass with respect to the amount of fixed carbon that can be reduced.

The agglomerate may contain a binder or the like as a component other than the iron oxide-containing substance, the carbonaceous material, and the melting point modifier. As the binder, for example, polysaccharides (for example, starch such as corn starch and wheat flour) can be used.

The iron oxide-containing substance, carbonaceous material, and melting point modifier are preferably pulverized in advance before mixing. For example, the iron oxide-containing substance has an average particle size of 10 to 60 μm, the carbonaceous material has an average particle size of 10 to 60 μm, and the melting point adjuster has an average particle size of 5 to 90 μm, for example. It is recommended to grind.

The method of pulverizing the iron oxide-containing substance or the like is not particularly limited, and a known method can be adopted. For example, a vibration mill, a roll crusher, a ball mill, or the like may be used.

As the mixer for mixing the raw material mixture, for example, a rotating container mixer or a fixed container mixer can be used. 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.

Examples of the agglomerating machine for agglomerating the raw material mixture include a plate granulator (disk granulator), a drum granulator (cylindrical granulator), and a twin roll briquette molding machine. Can be used.

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, preferably a pellet shape or a briquette shape.

[Heating process]
In the heating step of the present invention, it is preferable to heat so that a part of the agglomerate obtained in the agglomeration step is melted to reduce iron oxide contained in the agglomerate. That is, it is recommended that the agglomerate be heated at a temperature equal to or higher than a temperature at which a part of the agglomerate melts and lower than a temperature at which it completely melts. Specifically, the agglomerate is supplied to a heating furnace and heated in a temperature range of, for example, 1200 to 1450 ° C. (more preferably 1200 to 1400 ° C., and still more preferably 1200 to 1350 ° C.). What is necessary is just to reduce | restore the iron oxide contained with a carbonaceous material and to manufacture (granular) metallic iron. This temperature range is a temperature at which a part of the components is melted in the agglomerate, but there is almost no oozing out of the melt, and the agglomerate is maintained and the whole agglomerate is not melted. By heating in this temperature range, a metallic iron-containing sintered body in which granular metallic iron and slag resulting from gangue are mixed inside the outer shell is obtained.

In the present invention, the heating of the agglomerate is such that the melting amount of the CaO—SiO ₂ —Al ₂ O ₃ ternary oxide contained in the agglomerate is 50% by mass or more of the amount of the ternary oxide. It is preferable to carry out at the temperature which added 100 degreeC to the temperature which becomes. That is, when the component composition of the agglomerate is determined, the melting amount of the CaO—SiO ₂ —Al ₂ O ₃ ternary oxide contained in the agglomerate is 50 mass of the ternary oxide amount. The temperature t that is at least% is obtained by calculation, and the agglomerate may be heated at a temperature equal to or higher than a temperature obtained by adding 100 ° C. to the temperature t (t + 100 ° C.). By heating at a temperature of “t + 100” ° C. or higher, the gangue contained in the agglomerate can be sufficiently melted, and the molten gangue aggregates and promotes separation from (granular) metallic iron. Therefore, the obtained (granular) metallic iron and slag mixture has good separability between (granular) metallic iron and slag.

The melting amount of the ternary oxide can be calculated using thermodynamic database software. In the present invention, FactSage 6.2 (manufactured by Thermfacts and GTT-Technologies) and thermodynamic databases FAST53 and FToxide were used.

As the heating furnace, a known furnace may be used, for example, a moving hearth type heating furnace may be used. The moving hearth type heating furnace is a heating furnace in which the hearth moves in the furnace like a belt conveyor, and specifically, a rotary hearth furnace can be exemplified. The rotary hearth furnace is designed in a circular shape (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 Is reduced by heating (circular) to produce 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 granular metallic iron contained in the mixture contained in the outer shell of the metallic iron-containing sintered body according to the present invention obtained by heating the agglomerate has an average particle size of about 1 μm to 3 mm.

[Crushing and magnetic separation process]
The metallic iron-containing sintered body obtained in the heating step may be pulverized and then separated into (granular) metallic iron and slag by magnetic separation and recovered. As a method for pulverizing the sintered metal-containing sintered body, a known method can be adopted. For example, a vibration mill, a roll crusher, a ball mill, a roller mill, a hammer mill, or the like may be used. Also, known conditions can be adopted for the conditions for magnetic separation.

[Preferred embodiment]
In the present invention, in the heating step, when the maximum temperature when heating the agglomerate is T (° C.), melting of gangue contained in the agglomerate at a temperature subtracted 100 ° C. from this temperature T It is preferable to adjust the blending amount of the melting point adjusting agent so that the amount is 50% by mass or more of the gangue. That is, when the heating temperature of the agglomerate is determined, it is preferable to previously adjust the melting point of the component contained in the agglomerate using a melting point adjusting agent so that the amount of melting during heating is increased. . And when the agglomerate is heated, the gangue at a temperature subtracted 100 ° C. from the maximum temperature T at the time of heating so that 50% by mass or more of the gangue contained in the agglomerate is surely melted. What is necessary is just to mix | blend the said melting | fusing point adjusting agent on the basis of the amount of fusion | melting, and to adjust the component of an agglomerate.

The melting amount of the gangue may be determined based on the amount of three components of CaO, SiO ₂ , and Al ₂ O ₃ among the gangue contained in the agglomerate.

This application claims the benefit of priority based on Japanese Patent Application No. 2012-99165 filed on April 24, 2012. The entire contents of Japanese Patent Application No. 2012-99165 filed on April 24, 2012 are incorporated herein by reference.

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.

[Experimental Example 1]
A raw material mixture containing an iron oxide-containing substance and a carbon material was agglomerated, and the obtained agglomerate was heated in an electric furnace to produce a sintered body.

As the iron oxide-containing substance, iron ore having the component composition shown in Table 1 below was used. In the table, T.M. Fe is the total iron content; C means the total carbon content. As the carbon material, coal having a component composition shown in Table 2 below was used.

A mixture of limestone as a component adjusting agent and wheat flour as a binder in the above iron ore and coal was used as a raw material mixture, and a small amount of water was added thereto to produce φ19 mm carbon material-incorporated pellets by rolling granulation. The obtained carbon material-containing pellets were dried at 180 ° C. to produce dry pellets. The composition of the dried pellets is shown in Table 3 below. Table 3 below shows the basicity (CaO / SiO ₂ ) obtained from the CaO amount and the SiO ₂ amount contained in the dried pellet, the Al ₂ O ₃ / SiO ₂ value obtained from the Al ₂ O ₃ amount and the SiO ₂ amount. Is also shown.

The obtained dried pellets were supplied to an electric furnace in a nitrogen atmosphere and heated at 1300 ° C. for 18 minutes or 1350 ° C. for 18 minutes, and then cooled to room temperature in the furnace to produce a sintered body.

FIG. 1 shows a drawing-substituting photograph showing a longitudinal section of a sintered body obtained by heating at 1300 ° C. for 18 minutes. In FIG. 1, the white part means metallic iron, the gray part means slag or resin, and the black part means a gap. Note that it is difficult to distinguish slag and resin because they have the same color tone.

As shown in FIG. 1, the sintered body obtained by heating had a substantially spherical shape with a top and bottom direction diameter of 12.4 mm, a lateral direction diameter of 14.2 mm, and a slightly flat bottom surface. This sintered body had a structure in which a mixture containing granular metallic iron and slag was included inside an outer shell containing metallic iron and slag.

FIG. 2 shows a drawing substitute photograph in which a part of the outer shell is enlarged in the longitudinal section of the sintered body shown in FIG. As shown in FIG. 2, the outer shell had a network of metallic iron, and the hole portion was a void or slag was present therein. The thickness of the outer shell was a maximum of 2.4 mm on the upper side (top side) close to the heating source, and became thinner toward the lower side (ground side), and almost no outer shell was formed on the bottom surface. The area ratio of the outer shell to the area of the entire sintered body was 17.3%.

On the other hand, the inside of the outer shell contained a mixture of granular metallic iron and slag, and voids were also present. As for the size of the granular metallic iron, the maximum diameter was 2.4 mm, the minimum diameter that could be observed was 0.08 mm, and the average particle size was about 0.3 mm.

Next, the sintered body obtained by heating at 1300 ° C. for 18 minutes or 1350 ° C. for 18 minutes was pulverized, and the obtained pulverized product was magnetically separated and separated into metallic iron and slag. The sintered body was pulverized by using a vibration mill, pulverized to a diameter of 1 mm or less, and then magnetically separated using a magnet. For magnetic separation, a 2000 gauss magnet was used, the magnetic force at the sample position was adjusted from 200 gauss to 500 gauss, and a method of repeated magnetizing operation was adopted. Table 4 below shows the component compositions of the magnetically adsorbed material and the non-magnetically adsorbed material obtained by magnetic separation. In the table, M.M. Fe indicates the amount of metallic iron.

Table 3 and Table 4 below can be considered as follows. Regarding dry pellets before heating, T.W. The ratio of the total amount of SiO ₂ and Al ₂ O ₃ to Fe ([(7.56 + 0.61) /49.33] × 100) was 16.56%. On the other hand, regarding the magnetic deposit obtained by pulverization and magnetic separation after heating, the T.C. The ratio of the total amount of SiO ₂ and Al ₂ O ₃ to Fe ([(4.82 + 0.42) /90.51] × 100) was reduced to 5.8%. From this result, it can be seen that slag typified by SiO ₂ and Al ₂ O ₃ is recovered as non-magnetic deposits. Therefore, most of the magnetic deposits are composed of iron, and it can be seen that the iron recovery rate can be improved by using the sintered metal-containing sintered body of the present invention.

Next, an average value was obtained by weighting the component compositions of the magnetically adsorbed material and the non-magnetically adsorbed material shown in Table 4 below from the amount ratios thereof. This average value corresponds to the component composition of the sintered metal-containing sintered body after heating in an electric furnace and before magnetic separation. Of the average values shown in Table 4 below, the basicity of slag (CaO / SiO ₂ ) calculated from the CaO amount and the SiO ₂ amount is 0.292, and the total carbon amount (TC) is 3.55 mass. %Met.

[Experiment 2]
In the above experimental example 1, the dry pellets of the component compositions a to c shown in the following Table 5 or the dry briquettes of the component compositions a and b shown in the following Table 5 were obtained by changing the blending amounts of iron ore, coal, component modifier and binder. Manufactured. The size of the dried pellet is φ19 mm, and the size of the dried briquette is 9 cc.

In Table 5 below, the basicity (CaO / SiO ₂ ) and the values of Al ₂ O ₃ / SiO ₂ are calculated based on each component composition.

The obtained dried pellets or dried briquettes were supplied to an electric furnace in a nitrogen atmosphere and heated at 1300 ° C. for 18 minutes or 1350 ° C. for 18 minutes, and then cooled to room temperature in the furnace to produce a sintered body.

Similarly, a plurality of dry pellets or dry briquettes having a component composition different from the component composition shown in Table 5 below were produced, and a sintered body was produced under the above conditions.

The obtained sintered body was crushed manually, and the outer shell and the mixture contained inside the outer shell were separated manually. In addition, since a part of the mixture was firmly adhered to the outer shell, all the mixture could not be separated from the outer shell by manual work.

The outer shell and the mixture contained inside the outer shell were separately pulverized, and the obtained pulverized material was separately magnetically separated. The pulverization was performed using a vibration mill so that the diameter was 1 mm or less. Magnetic separation was performed under the same conditions as in Experimental Example 1. The magnetized material obtained by magnetic separation was metallic iron with a small amount of slag on both the outer shell side and the mixture side, and the non-magnetic material was accompanied with a small amount of metallic iron on both the outer shell side and the mixture side. It was slag.

The basicity (CaO / SiO ₂ ) was calculated from the amount of CaO and the amount of SiO ₂ contained in the magnetic deposit for each of the outer shell-side magnetic deposit and the mixture-side magnetic deposit. Further, the amount of SiO ₂ contained in the magnetic deposit and the T.P. From the amount of Fe, SiO ₂ / T. The value of Fe was calculated. The basicity (CaO / SiO ₂ ) of the magnetic deposit and the SiO ₂ / T. A graph showing the relationship with the value of Fe is shown in FIG. The range of the arrow shown in FIG. 3 shows the component composition before magnetic separation. In FIG. 3, □ shows the result of the outer shell of the pellet, ■ shows the result of the mixture inside the pellet, Δ shows the result of the outer shell of the briquette, and ▲ shows the result of the mixture inside the briquette.

As is apparent from FIG. 3, it can be seen that the basicity of the magnetic deposit obtained by magnetic separation is smaller for both pellets and briquettes than the basicity before magnetic separation. In addition, the T. It can also be seen that the ratio of SiO _{2 to} Fe is small. T.A. The fact that the ratio of SiO _{2 to} Fe is small means that iron and slag represented by SiO ₂ are well separated.

From the above results, it can be seen that the separability between metallic iron and slag can be improved by reducing the basicity of the magnetic deposit. In this experimental example, the result of measuring the basicity of the magnetic deposit was shown. However, it has been confirmed that the basicity of the non-magnetic deposit is almost equal to the basicity of the magnetic deposit.

Next, the amount of S contained in the magnetic deposit and the T.P. From the amount of Fe, S / T. The value of Fe was calculated. The magnetized SiO ₂ / T. The value of Fe and the S / T. A graph showing the relationship with the value of Fe is shown in FIG. In FIG. 4, □ shows the result of the outer shell of the pellet, ■ shows the result of the mixture inside the pellet, Δ shows the result of the outer shell of the briquette, and ▲ shows the result of the mixture inside the briquette. The straight lines (solid line and dotted line) shown in FIG. 4 are based on the dotted line drawn by the method of least squares based on the result of the outer shell of the pellet and briquette among the magnetic materials and the result of the mixture inside the pellet and the briquette. The solid line drawn by the method of least squares.

From FIG. 4, among the magnetic deposits, the granular metallic iron contained in the sintered metal-containing sintered body is S / T. It can be seen that Fe is 0.0017 or less.

Also, when heated at 1300 ° C. From FIG. 4, SiO ₂ / T. The smaller the value of Fe, the more S / T. It can be seen that the value of Fe tends to decrease. S / T. The small value of Fe means that there is a lot of S in the slag.

Here, based on the obtained data, SiO ₂ / T. When extrapolated so that the value of Fe approaches 0, as shown in FIG. The value of Fe is considered to approach 0. Therefore, it can be seen that when heated to 1300 ° C., metallic iron with a low S content can be produced.

On the other hand, in the case of heating at 1350 ° C., SiO ₂ / T. When extrapolated so that the value of Fe approaches 0, S / T. The value of Fe does not approach 0, and SiO ₂ / T. When the value of Fe is 0, S / T. The value of Fe is 0.00148. When heated to 1350 ° C., S / T. The reason why the value of Fe does not approach 0 is that the heating temperature is too high, so the carbon concentration decreases early in the heating, and the outer shell portion where the temperature is rising has sulfur (S) in the metallic iron as the temperature rises. It is thought that it becomes easy to adsorb. Therefore, it turns out that metal iron with few S content can be manufactured by setting heating temperature low and isolate | separating metal iron and slag.

Next, the SiO ₂ / T. FIG. 5 shows a graph showing the relationship between the value of Fe and the value of C content (TC) contained in the magnetic deposit. In FIG. 5, □ shows the result of the outer shell of the pellet, ■ shows the result of the mixture inside the pellet, Δ shows the result of the outer shell of the briquette, and ▲ shows the result of the mixture inside the briquette. From FIG. 5, the amount of metallic iron (magnetized material) contained in the outer shell constituting the metallic iron-containing sintered body is 0.3 to 2.5% by mass, whereas It can be seen that the amount of C of the granular metallic iron (magnetized material) contained in the mixture contained inside the shell is 1.5 to 5% by mass.

[Experiment 3]
In Experimental Example 3, the influence of the melting amount of the CaO—SiO ₂ —Al ₂ O ₃ ternary oxide contained in the agglomerate and the heating temperature in the electric furnace on the magnetic separation results was examined.

The raw material mixture containing the carbonaceous material, the melting point adjusting agent, and iron ore A or iron ore L having the composition shown in Table 6 below is agglomerated, and the obtained agglomerate is heated in an electric furnace, and the obtained reduced pellets , And reduced iron was produced by magnetic separation of the pulverized product. At this time, CaO, SiO ₂ , Al ₂ O ₃ , or MgO was added to iron ore A or iron ore L to prepare agglomerates having different gangue amounts.

The iron ore A or the iron ore L, a carbon material, a melting point adjusting agent, and a binder were mixed, and an agglomerate having a diameter of 19 mm was produced by rolling granulation. The carbonaceous material was blended with a carbonaceous material having ± 2% by mass of fixed carbon with respect to the amount of oxygen bound as iron oxide contained in iron ore. As the melting point adjusting agent, limestone (CaCO ₃ ) and silica stone were blended. As the binder, as in Experimental Example 1, wheat flour was blended. Table 7 below shows the component composition of the agglomerated product after drying.

Further, based on the amounts of CaO, SiO ₂ , and Al ₂ O ₃ contained in the agglomerated material after drying, the melting temperature L.C. of the CaO—SiO ₂ —Al ₂ O ₃ ternary oxide contained in the agglomerated material is determined. T is calculated using thermodynamic database software “FactSage” and is shown in Table 7 below.

Next, the obtained agglomerate was charged into an electric furnace and heated for 18 minutes to reduce iron oxide contained in the agglomerate, thereby producing reduced pellets containing reduced iron and slag. The temperature in the electric furnace was 1300 ° C or 1350 ° C. The atmosphere in the electric furnace was No. 1 using iron ore A. Nos. 1 to 3 were N ₂ gas atmosphere (N ₂ gas 100% by volume), and No. 1 using iron ore L was used. The volume ratio of 4 to 6 was adjusted to CO ₂ gas: N ₂ gas = 30: 70.

In addition, the melting temperature of the CaO—SiO ₂ —Al ₂ O ₃ ternary oxide is calculated from the heating temperature T in the electric furnace. A value obtained by subtracting T (TLT) was calculated and is also shown in Table 7 below. TL. When T is a negative value, the melting temperature L. of CaO—SiO ₂ —Al ₂ O ₃ ternary oxide is shown. It means heating at a temperature below T.

Further, the melting amount of the CaO—SiO ₂ —Al ₂ O ₃ ternary oxide at a temperature lower than the heating temperature T by 100 ° C. (T-100 ° C.) was calculated using the above “FactSage”. The results are also shown in Table 7 below. In Table 7 below, the calculation result of the melting amount of the CaO—SiO ₂ —Al ₂ O ₃ ternary oxide at a temperature lower than the heating temperature T by 50 ° C. (T-50 ° C.) is also shown as a reference value. Show.

Next, the obtained reduced pellets were pulverized so as to have a diameter of 3 mm or less using a ball mill and a vibration mill in the same manner as in Experimental Example 1, and then magnetically separated using a magnet. Table 7 below shows the ratio of non-magnetized substances (non-magnetization ratio) obtained by magnetic separation.

Next, FIG. 6 shows the melting temperature of the CaO—SiO ₂ —Al ₂ O ₃ ternary oxide from the heating temperature T in the electric furnace. The relationship between the value obtained by subtracting T (TLT) and the non-magnetization rate is shown. In FIG. Results 1 to 3 are shown in ◆, No. The results of 4-6 are indicated by ■. From FIG. It can be seen that there is no correlation between T and the non-magnetization rate. In particular, as in the iron ore L, when the amount of SiO ₂ contained in the iron ore increases, it can be seen that the variation in the non-magnetization rate increases.

Next, FIG. 7 shows the relationship between the amount of melting of the CaO—SiO ₂ —Al ₂ O ₃ ternary oxide at a temperature lower than the heating temperature T by 100 ° C. (T-100 ° C.) and the non-magnetization rate. . In FIG. Results 1 to 3 are shown in ◆, No. The results of 4-6 are indicated by ■. FIG. 7 shows that the non-magnetization rate increases when the melting amount of the CaO—SiO ₂ —Al ₂ O ₃ ternary oxide at a temperature lower than the heating temperature T by 100 ° C. is 50 mass% or more. . In other words, when the agglomerate is heated at a temperature equal to or higher than 100 ° C. added to the temperature at which the melting amount of the CaO—SiO ₂ —Al ₂ O ₃ ternary oxide is 50 mass% or higher, the non-magnetization rate increases. It can be said.

As described above, it can be seen that according to the present invention, the separation between reduced iron and slag is improved, and the recovery rate of reduced iron can be improved.

Claims (7)

A metallic iron-containing sintered body characterized in that a mixture containing granular metallic iron and slag is included inside the outer shell containing metallic iron and slag, and the temperature is 1000 ° C. or lower. The metallic iron-containing sintered body according to claim 1, wherein metallic iron is formed in a network shape in the outer shell. The metallic iron-containing sintered body according to claim 1 or 2, wherein the granular metallic iron contained in the mixture has an average particle size of 3 mm or less (not including 0 mm). When the average composition of the slag contained in the sintered metal-containing sintered body according to claim 1 or 2 is measured, the basicity [CaO / SiO ₂ ] of the slag obtained from the CaO amount and the SiO ₂ amount is 0. The metallic iron-containing sintered body according to claim 1 or 2, which is 2 or more and less than 0.9. When the average component composition of the granular metallic iron contained in the metallic iron-containing sintered body according to claim 1 or 2 is measured, the ratio of S amount to Fe amount (S / Fe) is 0.0017 or less (0 The metallic iron-containing sintered body according to claim 1 or 2, wherein the sintered body contains metallic iron. The amount of C is 0.3 to 2.5% by mass when the average component composition of the metal iron contained in the metal iron-containing sintered body according to claim 1 or 2 is measured. The metallic iron containing sintered compact of description. The C content is 1.5 to 5% by mass when the average component composition of the granular metallic iron contained in the sintered metal-containing sintered body according to claim 1 or 2 is measured. Metallic iron-containing sintered body.

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