JP2013249496A - Method for manufacturing mixture of reduced iron and slag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique of enhancing the separability of reduced iron from slag concerning a mixture of reduced iron and slag, obtained in a semi-molten state in which the entire agglomerate is not perfectly molten.SOLUTION: A method for manufacturing a mixture of reduced iron and slag is provided which comprises in the given order the step of agglomerating a feedstock mixture prepared by mixing a substance containing iron oxide and titanium oxide with a carbon material and further a melting point regulator and the step of reducing iron oxide contained in the agglomerate by heating the obtained agglomerate so as to partly melt the agglomerate. In the heating, the agglomerate is heated at temperature equal to higher than a temperature at which part of the agglomerate melts and lower than a temperature at which it perfectly melts. It is desirable that the slag basicity of [CaO/SiO2] is adjusted to 0.2-0.9, that the amount of the melting point regulator added is adjusted on the basis of the amount of the five components of CaO, SiO2, Al2O3, MgO, and TiO2 contained in the agglomerate, and that the amount of the gangue molten is 55 mass% or more.

Description

  The present invention relates to a method for producing a mixture of reduced iron and slag by heating an agglomerate containing a substance containing iron oxide and titanium oxide and a carbonaceous material.

As an iron making method to produce reduced iron from iron oxide-containing materials such as iron ore,
(1) A method of reducing the iron oxide contained in the calcined pellets with a reducing gas by heating the calcined pellets sintered with iron ore as the main raw material to about 1000 ° C. in a shaft furnace,
(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 iron oxide contained,
(3) The agglomerate obtained by mixing and agglomerating iron ore and carbonaceous material is supplied to a moving hearth furnace and heated to about 1450 ° C. to melt the reduced iron. A method of separating reduced iron and slag by the difference in surface tension with slag, etc.
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 (1), for example, the technique of Patent Document 1 is known. Patent Document 1 describes that iron ore is directly reduced and pulverized, iron and gangue are separated, and then both are further pulverized to recover iron from each. CO gas or H ₂ gas can be used as the reducing gas, heating temperature should be 700 to 1200 ° C., crushing can be performed using a roll crusher or the like that can extend metallic iron into pieces, separation of iron and gangue Describes the combination of separation with a 20 mesh sieve (aperture 0.83 mm) and magnetic separation.

  Regarding the method (2), for example, the technique of Patent Document 2 is known. In Patent Document 2, a mixture containing an iron raw material and coal is heated and reduced 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. . 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 content and high in slag content, 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 Documents 3 and 4 are known.

  Among these, in Patent Document 3, by producing a carbon-containing pellet composed of a plurality of types of dust and carbonaceous material, and reducing this 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.

  In Patent Document 4, a carbon-containing pellet composed 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.

  By the way, some of the iron ores contain useful non-ferrous metal oxides such as titanium oxide in addition to iron oxide. Patent Document 5 discloses a raw material containing titanium oxide, iron oxide, and a carbonaceous reducing agent. The mixture is heated in a rotary hearth furnace to reduce iron oxide in the mixture to obtain reduced iron, and then these are further heated to melt the reduced iron and separate from the titanium oxide-containing slag. The manufacturing method of the titanium oxide containing slag which discharges | emits and collects the titanium oxide containing slag outside a furnace is described.

  However, in Patent Documents 3 to 5, reduced iron and slag produced as a by-product are separated by completely melting reduced iron, and reduced iron and slag obtained in a state where the agglomerates are not completely melted. No consideration is given to improving the separability of the mixture.

US Pat. No. 6,048,382 JP 2002-363624 A Japanese Patent Laid-Open No. 10-147806 JP 2009-91664 A Japanese Patent No. 4153281

  The present invention has been made by paying attention to the above-described circumstances, and the object thereof is to provide a mixture of reduced iron and slag obtained in a semi-molten state in which the agglomerates are not completely melted. The object is to provide a technique capable of improving the separability. Another object of the present invention is to provide a method in which titanium oxide-containing slag having a high titanium oxide concentration can be used as a metal titanium raw material by recovering titanium oxide as slag.

  The method for producing a mixture of reduced iron and slag according to the present invention that can solve the above-mentioned problems is a mass of a material containing iron oxide and titanium oxide, and a raw material mixture in which a carbon material is further blended with a melting point regulator. It has a gist in that it includes a step of forming, and a step of heating so that a part of the obtained agglomerate melts and reducing iron oxide contained in the agglomerate in this order. .

  Moreover, the said subject is the process of agglomerating the raw material mixture which mix | blended the melting | fusing point regulator with the substance containing iron oxide and titanium oxide, and carbonaceous material, and a part of obtained agglomerate melts. It has a gist in that it includes a step of reducing the iron oxide contained in the agglomerate in this order by heating the agglomerate at a temperature equal to or higher than the temperature and less than a temperature at which it completely melts. It can also be achieved by a method for producing a mixture of reduced iron and slag.

In the present invention, the melting point adjusting agent includes at least a CaO supply substance, and the amount of the CaO supply substance to be blended in the agglomerate is determined based on the slag basicity determined from the CaO amount and the SiO ₂ amount in the agglomerate [ CaO / SiO ₂ ] is preferably controlled in the range of 0.2 to 0.9. As the CaO feed material, for example, CaO, Ca (OH) _2, and it is preferable to blend at least one selected from the group consisting of CaCO _3.

In the present invention, the melting amount of the gangue contained in the agglomerate at a temperature subtracted by 100 ° C. from the maximum temperature when the agglomerate is heated by adjusting the blending amount of the melting point adjusting agent is 55% by mass or more. It is preferable that The melting amount of the gangue may be determined based on the amounts of the five components CaO, SiO ₂ , Al ₂ O ₃ , MgO, and TiO ₂ contained in the agglomerate. The heating of the agglomerate is such that the melting amount of the CaO—SiO ₂ —Al ₂ O ₃ —MgO—TiO ₂ ternary oxide contained in the agglomerate is 55% by mass or more of the quinary oxide amount. It is preferable to carry out at the temperature which added 100 degreeC to the temperature used as above.

As the substance containing iron oxide and titanium oxide, for example, iron ore containing 40 to 60% by mass of Fe and 7 to 20% by mass of TiO ₂ is preferably used. The carbon material is preferably blended so that the amount of fixed carbon contained in the carbon material is ± 5% by mass with respect to the amount of fixed carbon capable of reducing the iron oxide contained in the agglomerate. The agglomerate is preferably heated at, for example, 1200 to 1500 ° C.

  In this invention, the process of grind | pulverizing the mixture of the reduced iron and slag obtained by the manufacturing method mentioned above to a diameter of 8 mm or less (it does not contain 0 mm), and the process of carrying out the magnetic separation of the obtained grind | pulverized material in this order. A method for separating reduced iron and slag is also included.

Further, the present invention also includes non-magnetized substances and magnetized substances selected by the separation method described above, and the non-magnetized substances contain, for example, 40% by mass or more of TiO _2. , SiO ₂ is suppressed to 8% by mass or less (not including 0% by mass).

  According to the present invention, an agglomerate in which a substance containing iron oxide and titanium oxide and a carbonaceous material is further blended with a melting point adjusting agent (excluding those affecting the melting point of iron) is prepared, and this agglomerate is prepared. A mixture in which reduced iron and slag are mixed in a separated state (hereinafter sometimes referred to as reduced pellets) can be produced by heating so that a part of the molten iron is melted and not completely melted. The obtained mixture can be easily separated into reduced iron and slag by, for example, pulverization and magnetic separation, and each can be used for a desired application. At this time, reduced iron is mainly separated on the magnetized material side, and titanium oxide is separated on the non-magnetized material side as slag. Therefore, according to the present invention, reduced iron and titanium oxide can be easily separated. That is, according to the present invention, it is possible to separate and recover titanium oxide as a useful non-ferrous metal oxide in addition to reduced iron.

In the present invention, (a) after considering the heating temperature, the blending amount of the melting point adjusting agent is adjusted so that the melting amount of the gangue contained in the agglomerate is not less than a predetermined amount, or (b ) In consideration of the melting amount of CaO—SiO ₂ —Al ₂ O ₃ —MgO—TiO ₂ ternary oxide contained in the agglomerate, the heating temperature of the agglomerate is usually selected. It has also been clarified that reduced iron can be produced using iron ore containing iron oxide and titanium oxide that has not been used.

FIG. 1 is a graph showing the relationship between the heating temperature T and the non-magnetization rate. FIG. 2 shows the relationship between the melting amount of the CaO—SiO ₂ —Al ₂ O ₃ —MgO—TiO ₂ ternary oxide at a temperature lower than the heating temperature T by 100 ° C. (T-100 ° C.) and the non-magnetization rate. It is a graph which shows.

  The present inventors have used as a raw material a substance containing iron oxide and titanium oxide that has been rarely used in the past (hereinafter sometimes referred to as an iron oxide-containing substance). Separation when a mixture of reduced iron and slag obtained by heating the agglomerate containing the material to melt partly and not completely melt into separated iron and slag We have been intensively studying to improve the performance. As a result, if a melting point adjusting agent is further added to the mixture of the iron oxide-containing substance and the carbonaceous material, the separation pellets obtained by heating the agglomerate can be separated into reduced iron and slag. As a result, the present invention was completed.

In addition, the present inventors have better separated reduced iron and slag,
(A) When the heating temperature T when the agglomerate is heated is determined, the gangue component contained in the agglomerate at a temperature subtracted 100 ° C. from the maximum temperature when the agglomerate is heated Adjusting the blending amount of the melting point adjusting agent (for example, CaO supply substance) so that the melting amount is 55% by mass or more,
(B) When the heating temperature T when heating the agglomerate is not determined, the agglomerate is added to the CaO—SiO ₂ —Al ₂ O ₃ —MgO—TiO ₂ ternary contained in the agglomerate. It has also been clarified that heating may be performed at a temperature obtained by adding 100 ° C. to a temperature at which the melting amount of the system oxide is 55% by mass or more of the amount of the ternary system oxide.

  In addition, the present inventors have also studied to produce reduced iron used as a raw material for electric furnace refining by separating the mixture into reduced iron and slag. As a result, reduced iron and slag (gangue component) are mixed by heating and reducing the agglomerate containing the iron oxide-containing substance, the carbonaceous material, and the melting point modifier to a partially molten state. These are reduced pellets in a state that can be easily separated into reduced iron and slag, and it has been found that the reduced pellets can be separated into reduced iron and slag by processing such as pulverization and magnetic separation. Hereinafter, the present invention will be described in detail.

  In producing a mixture of reduced iron and slag in the present invention, a step of agglomerating a raw material mixture in which a melting point modifier is further blended with a substance containing iron oxide or the like and a carbonaceous material (hereinafter referred to as an agglomeration step); It is important to include, in this order, a step of heating so that a part of the obtained agglomerate melts and reducing iron oxide contained in the agglomerate (hereinafter referred to as a heating step). 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 can be reduced.

[Agglomeration process]
In the agglomeration process of the present invention, a material containing iron oxide and titanium oxide (containing material such as iron oxide) and a carbon material further blended with a melting point adjusting agent are used as a raw material mixture. The melting point modifier means a substance that affects the melting point of components other than iron (especially gangue) contained in the agglomerate, excluding substances that affect the melting point of iron (for example, carbon). . 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. As a result, melting of the gangue component 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. Thus, in the present invention, a mixture of reduced iron and slag 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.

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. it is preferred that SiO ₂₎ is adjusted in the range of 0.2 to 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 —MgO—TiO ₂ ternary oxide) contained in the agglomerate is lowered. Can be made. 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 0.7 or less.

The substance containing iron oxide or the like is a substance containing iron oxide and titanium oxide. Examples of the substance containing iron oxide include iron ore (for example, titanomagnetite ore), sand iron, iron making dust, non-ferrous refining residue, iron making waste, and the like. As said iron oxide etc. containing materials, the iron ore containing 40-60 mass% of Fe can be used, for example. As the like containing material above the iron oxide, for example, may be used iron ores containing TiO ₂ 7 to 20% by weight.

In the present invention, an agglomerate is produced by agglomerating a raw material mixture containing a substance containing iron oxide or the like, a carbon material, and a melting point modifier. Then, this agglomerate is heated to a semi-molten state in which a part of the agglomerate is melted, so that the ash content in the carbonaceous material and the melting point modifier are used as a flux and melted in the agglomerate. Partial production of slag, aggregation of reduced iron can be achieved, and reduced iron can be produced in a short time. That is, when heating an agglomerate containing a substance containing iron oxide or the like, a carbonaceous material, and a melting point modifier as in the present invention, 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 reduced iron is quickly produced. Therefore, in the agglomerate, reduced iron and gangue such as SiO ₂ are generated separately, so even if reduced iron and slag are mixed, the gangue is easily crushed by crushing them. It can be separated into reduced iron and slag. At this time, since titanium oxide is recovered as slag, it can be easily separated from reduced iron. On the other hand, in the above method (1) in which pellets that do not have a conventional carbonaceous material are reduced with a reducing gas, a melting point adjusting agent is added to the agglomerate and the mixture is not heated to a semi-molten state. It was difficult to separate reduced iron and titanium oxide contained in the above-mentioned containing material such as iron oxide. Therefore, the iron oxide-containing material has not been used as commercial iron ore, but according to the present invention, such iron oxide-containing material can be used as an iron source.

  That is, reduced iron can also be produced by a method of reducing calcined pellets containing iron ore with a reducing gas in a shaft furnace at about 1000 ° C. as in the method (1) described above, but this method exceeds 1200 ° C. When reducing with a reducing gas at a high temperature, the reduced pellets adhere to each other to form a large lump, and do not descend within the shaft, or are difficult to discharge. Therefore, the heating temperature needs to be 1200 ° C. or less. However, if the heating is performed at 1200 ° C. or less, the reduced iron and the gangue are difficult to be pulverized and separated because the agglomeration of the reduced iron becomes insufficient even if the heating time is increased.

  As the carbon material used in the present invention, for example, coal or coke can be used. The carbonaceous material should just contain the fixed carbon of the quantity which can reduce the iron oxide contained in the said agglomerate. Specifically, the amount of fixed carbon contained in the carbon material may be within a range of ± 5% by mass with respect to the amount of fixed carbon that can reduce iron oxide contained in the agglomerate.

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

  It is preferable to pulverize the above-mentioned substances such as iron oxide, carbonaceous material, and melting point adjusting agent before mixing. Specifically, for example, the iron oxide-containing material 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, for example. It is recommended to grind to 5 to 90 μm.

  A method for pulverizing the above-described substance such as iron oxide is not particularly limited, and a known method can be employed. For example, a vibration mill, a roll crusher, a ball mill, or the like may be used.

  As a mixer for mixing the raw material mixture, for example, a rotary container type mixer or a fixed container type 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, and preferably a pellet shape or a briquette shape.

[Heating process]
In the heating step of the present invention, it is important 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 important to heat the agglomerate at a temperature equal to or higher than the temperature at which a part of the agglomerate melts and less than the temperature at which it completely melts. Specifically, if the agglomerate is supplied to a heating furnace, for example, heated in a temperature range of 1200 to 1500 ° C., iron oxide contained in the agglomerate is reduced with a carbon material to produce reduced iron. Good. This temperature range is a temperature at which a part of the components melts in the agglomerate, but the melt does not leak out so that the shape of the agglomerate is maintained and the entire agglomerate is not melted. By heating in this temperature range, reduced pellets in which reduced iron and slag resulting from gangue are mixed are obtained.

In the present invention, the heating of the agglomerate is such that the melting amount (melt amount) of the CaO—SiO ₂ —Al ₂ O ₃ —MgO—TiO ₂ ternary oxide contained in the agglomerate is It is preferable to carry out at the temperature which added 100 degreeC to the temperature used as 55 mass% or more of the amount of original system oxides. That is, when the component composition of the agglomerate is determined, the melting amount of the CaO—SiO ₂ —Al ₂ O ₃ —MgO—TiO ₂ ternary oxide contained in the agglomerate is the quaternary system. What is necessary is just to obtain the temperature t that is 55% by mass or more of the oxide amount by calculation, and to heat the agglomerate at a temperature equal to or higher than a temperature (t + 100 ° C.) that is 100 ° C. added to the temperature t. 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 to promote separation from the reduced iron. Therefore, the obtained mixture of reduced iron and slag has good separation between reduced iron and slag.

  The amount of melting of the ternary oxide can be calculated using thermodynamic database software. In the present invention, FactSage 6.2 (manufactured by Thermfact 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 the same, and the agglomerate supplied on the hearth is Is reduced by heating to make reduced 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).

  As in the present invention, the reduced pellets obtained by heating the agglomerate in a semi-molten state in a furnace contain reduced iron particles having an average particle diameter of about 1 μm to 3 mm. On the other hand, the average particle diameter of the granular metallic iron obtained by completely melting the agglomerate in the furnace as in the methods (2) and (3) is about 8 mm or more.

  The reduced pellets obtained by the heating step (mixture of reduced iron and slag) may be pulverized to a diameter of 8 mm or less (not including 0 mm), and the obtained pulverized product may be magnetically separated. By pulverizing the reduced pellets to a diameter of 8 mm or less and then performing magnetic separation, it is possible to recover mainly reduced iron as a magnetic deposit and mainly recover slag as a non-magnetic deposit. And according to this invention, since said titanium oxide can be collect | recovered as this slag, isolation | separation with reduced iron and titanium oxide is attained. However, if the size when the reduced pellets are pulverized exceeds 8 mm in diameter, when magnetically separated, slag is mixed on the magnetized material side, or reduced iron is mixed on the non-magnetized material side, and reduced iron and slag are mixed. Separation is poor. Accordingly, the size when the reduced pellets are pulverized is preferably 8 mm or less in diameter.

  As a method of pulverizing the reduced pellets, a known method can be adopted, and for example, a vibration mill, a roll crusher, a ball mill, a roller mill, or the like may be used. As a method for magnetically separating the pulverized product, a known method can be employed.

According to the present invention, the amount of SiO ₂ contained in the magnetized product is 8% by mass or less, and the amount of TiO ₂ contained in the non-magnetized product is 40% by mass or more.

[Preferred embodiment]
In the present invention, when the maximum temperature when heating the agglomerate is T (° C.) in the heating step, the gangue contained in the agglomerate at a temperature obtained by subtracting 100 ° C. from the heating temperature T is used. It is preferable to adjust the blending amount of the melting point adjusting agent so that the melting amount is 55% by mass or more of the gangue amount. That is, when the heating temperature T of the agglomerate is determined, the melting point of the components contained in the agglomerate should be adjusted in advance using a melting point adjusting agent so that the amount of melting during heating increases. Is preferred. And, when the agglomerate is heated, the mass of the gangue at a temperature subtracted by 100 ° C. from the maximum temperature T at the time of heating is ensured so that 55% 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 component is determined based on the amount of CaO, SiO ₂ , Al ₂ O ₃ , MgO, and TiO ₂ among the gangue components contained in the agglomerate. That's fine.

  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.

[Experiment 1]
The raw material mixture containing the iron ore, the carbonaceous material, and the melting point adjusting agent having the composition shown in Table 1 below is agglomerated, and the obtained agglomerate is heated in an electric furnace to produce a mixture of reduced iron and slag (reduced pellets). Manufactured. In Table 1 below, T.W. Fe means the total amount of iron.

As the carbon material, a carbon material having ± 2 mol% of fixed carbon was blended with respect to the number of moles of oxygen bound as iron oxide contained in the iron ore. As the melting point adjusting agent, limestone (CaCO ₃ ) and silica stone were blended.

  A binder was further mixed into the raw material mixture containing iron ore, carbonaceous material, and melting point modifier shown in Table 1 below, and agglomerated by rolling granulation to produce an agglomerate having a diameter of 19 mm. As the binder, wheat flour was blended.

Table 2 below shows the component composition of the agglomerate after drying. The agglomerates a shown in Table 2 below have the highest melting point of slag produced as a by-product when iron oxide is reduced during heating by adjusting the basicity (CaO / SiO ₂ ) of the agglomerates. This is an example in which the component composition is adjusted to be low. The agglomerates b shown in Table 2 below are components so that the melting point of the CaO—SiO ₂ —Al ₂ O ₃ —MgO—TiO ₂ ternary oxide contained in the agglomerates is lowest. This is an adjusted example.

In Table 2 below, T.M. C represents the total carbon content, and CaO / SiO ₂ represents the basicity. CaO + SiO ₂ + Al ₂ O ₃ + MgO means the amount of gangue. Further, [TiO ₂ / (CaO + SiO ₂ + Al ₂ O ₃ + MgO + TiO ₂ )] × 100 means the titanium oxide (TiO ₂ ) concentration in the slag component.

Next, the obtained agglomerate was charged into an electric furnace and heated for 18 minutes to reduce iron oxide contained in the agglomerate. The heating temperature T in the electric furnace was 1300 ° C., 1350 ° C., or 1400 ° C., and the atmosphere in the electric furnace was adjusted to an N ₂ gas atmosphere. During the reduction of iron oxide, slag was by-produced, and a mixture of reduced iron and slag (reduced pellets) was obtained.

  The melted state when heated at each heating temperature T is shown in Table 3 below. In Table 3 below, “no melting” means a state in which no melt is generated in the agglomerate, and “with melting” means a state in which a melt is generated in the agglomerate. This indicates that a part of the agglomerate is melted.

  The obtained reduced pellets were pulverized with a vibration mill so as to have a diameter of 3 mm or less, and then magnetized and separated into a magnetized product and a non-magnetized product 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 the magnetic adhesion operation was repeated to perform magnetic separation. Table 3 below shows the component compositions of the magnetically adsorbed material and the non-magnetically adsorbed material obtained by magnetic separation. Note that M.M. Fe indicates the amount of metallic iron.

Table 3 below shows the ratios of the magnetic and non-magnetic products obtained by magnetic separation, the metallization rate (MetFe), the total amount of CaO + SiO ₂ + Al ₂ O ₃ + MgO, and the Ti recovery rate.
The metallization rate (MetFe) is calculated by the following formula.
MetFe (%) = [Amount of metallic iron (M.Fe)] / [Total amount of iron (T.Fe)] × 100

The Ti recovery rate as a magnetic deposit and the Ti recovery rate as a non-magnetic deposit are calculated by the following equations.
Ti recovery rate as magnetic deposit (%) = (Ti amount contained in magnetic deposit / Ti amount contained in agglomerate) × 100
Ti recovery rate as non-magnetic product (%) = (Ti amount contained in non-magnetic product / Ti content contained in agglomerate) × 100

  Based on Table 3 below, it can be considered as follows. No. shown in Table 3 below. Nos. 3, 5, and 6 were able to magnetically separate the reduced pellets into magnetized and non-magnetized materials. 1, 2, and 4 could not be separated by magnetic separation. Further, as is apparent from Table 3 below, it can be seen that as the heating temperature T is increased, the amount of Ti separated and recovered as non-magnetized material increases.

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

The raw material mixture containing the iron ore, carbonaceous material, and melting point modifier used in Experimental Example 1 was further mixed with a binder, and CaO and SiO ₂ were added. Agglomerates c and d having different gangue amounts of φ19 mm were produced. As the carbon material, a carbon material having ± 2 mol% of fixed carbon was blended with respect to the number of moles of oxygen bound as iron oxide contained in the iron ore. As the melting point adjusting agent, limestone (CaCO ₃ ) and silica stone were blended as in Experimental Example 1. As the binder, as in Experimental Example 1, wheat flour was blended.

Based on the amount of CaO and the amount of SiO ₂ contained in the agglomerate after drying, the basicity (CaO / SiO ₂ ) is calculated and shown in Table 4 below.

Moreover, based on the amount of CaO, SiO ₂ , Al ₂ O ₃ , MgO, TiO ₂ contained in the agglomerate after drying, CaO—SiO ₂ —Al ₂ O ₃ —MgO—TiO ₂ contained in the agglomerate. Melting temperature of ternary oxide T is calculated using thermodynamic database software “FactSage” and is shown in Table 4 below.

Furthermore, based on the amount of CaO, SiO ₂ , Al ₂ O ₃ , MgO, TiO ₂ contained in the agglomerated material after drying, the temperature at which the melting amount (melt generation amount) becomes 55% by mass is set to the above “FactSage”. Table 4 below shows the result [LT55 (° C.)].

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 a mixture of reduced iron and slag (reduced pellets). The heating temperature T in the electric furnace was 1300 ° C, 1350 ° C, or 1400 ° C. The atmosphere in the electric furnace was an N ₂ gas atmosphere (N ₂ gas 100% by volume).

Further, from the heating temperature T in the electric furnace, the melting temperature of the CaO—SiO ₂ —Al ₂ O ₃ —MgO—TiO ₂ ternary oxide L.P. A value obtained by subtracting T (TLT) is calculated and shown in Table 4 below. TL. When T is a negative value, the melting temperature of the CaO—SiO ₂ —Al ₂ O ₃ —MgO—TiO ₂ ternary oxide L. It means heating at a temperature below T.

Further, the melting amount of the CaO—SiO ₂ —Al ₂ O ₃ —MgO—TiO ₂ ternary oxide at a temperature lower than the heating temperature T by 100 ° C. (T-100 ° C.) was calculated using the “FactSage”. The results are also shown in Table 4 below. In Table 4 below, as a reference value, the melting amount of the CaO—SiO ₂ —Al ₂ O ₃ —MgO—TiO ₂ ternary oxide at a temperature lower than the heating temperature T by 50 ° C. (T-50 ° C.) is shown. The calculated results are also shown.

  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 4 below shows the ratio of non-magnetized substances obtained by magnetic separation (non-magnetization ratio).

  Next, FIG. 1 shows the relationship between the heating temperature T and the non-magnetization rate. In FIG. The results of 7 to 9 are shown. 10 to 12 results are shown.

  As apparent from Table 4 and FIG. 1 above, the temperature (LT 55 (° C.)) at which the melting amount (melt generation amount) is 55% by mass is 100 ° C. (ie, for Nos. 7 to 9). It can be seen that by heating to 1400 ° C. and 1350 ° C. for Nos. 10 to 12 or more, reduced iron and slag begin to separate, and the non-magnetization rate increases (No. 9, 11, 12).

Next, FIG. 2 shows the melting amount of the ternary oxide of CaO—SiO ₂ —Al ₂ O ₃ —MgO—TiO _{2 at a} temperature lower than the heating temperature T by 100 ° C. (T-100 ° C.), and the non-magnetization rate. Shows the relationship. In FIG. The results of Nos. 7 to 9 are shown by ◆, No. The results of 10 to 12 are indicated by □.

  As is clear from FIG. 2, when the melting amount (melt generation amount) is 55% by mass or more, metallic iron and slag begin to separate, and the nonmagnetic rate increases as the heating temperature T increases. I understand that.

  As described above, according to the present invention, the separation between reduced iron and slag is improved, and reduced iron and titanium oxide can be separated and recovered efficiently. Moreover, according to this invention, reduced iron can be collect | recovered efficiently.

Claims (14)

Agglomerating a material mixture containing a substance containing iron oxide and titanium oxide, a carbonaceous material, and a melting point modifier; and
A method for producing a mixture of reduced iron and slag, comprising heating in order that a part of the obtained agglomerate melts and reducing iron oxide contained in the agglomerate in this order . Agglomerating a material mixture containing a substance containing iron oxide and titanium oxide, a carbonaceous material, and a melting point modifier; and
A step of reducing the iron oxide contained in the agglomerate 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 the agglomerate is completely melted. The manufacturing method of the mixture of reduced iron and slag characterized by including in this order. The melting point adjusting agent contains at least a CaO supply substance, and the amount of CaO supply substance to be blended in the agglomerate is determined based on the slag basicity [CaO / SiO ₂ obtained from the CaO amount and the SiO ₂ amount in the agglomerate. ] Is adjusted so that it may become 0.2-0.9. The manufacturing method of Claim 1 or 2. The CaO as a feed _{material, CaO, Ca (OH) 2} , and a manufacturing method according to claim 3, blending at least one selected from the group consisting of CaCO _3.   The amount of melting of the gangue contained in the agglomerate at a temperature subtracted by 100 ° C from the maximum temperature when the agglomerate is heated by adjusting the blending amount of the melting point adjusting agent is 55% by mass or more. The manufacturing method in any one of 1-4. The manufacturing method according to claim 5, wherein the melting amount of the gangue is determined based on the amounts of five components of CaO, SiO ₂ , Al ₂ O ₃ , MgO, and TiO ₂ contained in the agglomerate. . The heating of the agglomerate is such that the melting amount of the CaO—SiO ₂ —Al ₂ O ₃ —MgO—TiO ₂ ternary oxide contained in the agglomerate is 55% by mass or more of the quinary oxide amount. The manufacturing method in any one of Claims 1-6 performed at the temperature which added 100 degreeC to temperature used as this.   The manufacturing method in any one of Claims 1-7 using the iron ore containing 40-60 mass% of Fe as a substance containing the said iron oxide and titanium oxide. Examples material containing iron oxide and titanium oxide, a manufacturing method according to claim 1 using an iron ore containing TiO ₂ 7 to 20% by weight.   The carbonaceous material according to any one of claims 1 to 9, wherein the carbonaceous material is blended so that a fixed carbon amount contained in the carbonaceous material becomes ± 5 mass% with respect to a fixed carbon amount capable of reducing iron oxide contained in the agglomerate. The manufacturing method of crab.   The manufacturing method according to any one of claims 1 to 10, wherein the agglomerate is heated at 1200 to 1500 ° C. A step of pulverizing a mixture of reduced iron and slag obtained by the production method according to claim 1 to a diameter of 8 mm or less (excluding 0 mm);
A method for separating reduced iron and slag, comprising a step of magnetically separating the obtained pulverized product in this order. The non-magnetized material selected by the separation method according to claim 12, wherein the non-magnetized material contains 40% by mass or more of TiO ₂ . 13. A magnetic material selected by the separation method according to claim 12, wherein the magnetic material contains 8% by mass or less (not including 0% by mass) of SiO ₂ .

Images