TWI820935B - Iron making method - Google Patents

Abstract

The iron making method in this case has the following steps: The ore beneficiation treatment step is to beneficiate high-crystalline iron ore with a ignition loss of 3 to 12 mass% to select at least a goethite-rich portion with an ignition loss of 4 mass% or more and an iron content of 55 mass% or more; The first agglomeration treatment step is to agglomerate the aforementioned goethite-rich portion into first calcined particles in a pellet calcining furnace; and In the first reduction step, the first calcined particles are loaded into a shaft furnace at a surface temperature of not less than 600°C and the first calcined particles are directly reduced using a reducing gas containing more than 60 volume % hydrogen.

Description

Iron making method

Field of invention The present invention relates to a method of making iron. This case claims priority based on Japanese Patent Application No. 2021-159551, which was filed in Japan on September 29, 2021, and its contents are cited here.

Background technology One of the known iron-making methods is the direct reduction iron-making method, which produces iron from raw materials containing iron oxide (by reducing iron oxide). The direct reduction iron-making method continues to develop on the background that the construction cost of the plant used to perform it is low, easy to operate, and can be operated in a small-scale plant. In particular, in the direct reduction ironmaking method of the shaft furnace system, various improvements are continuously being made to effectively utilize the reducing gas in the furnace.

Furthermore, recently, with the aim of reducing carbon dioxide emissions from the steel industry, a direct reduction iron-making process using hydrogen as a reducing gas has been developed. As representative examples, HYBRIT, MIDREX+H ₂ , etc., which utilize hydrogen obtained by electrolysis of water in a shaft-furnace direct reduction iron production method, are known.

Reduced iron produced by the direct reduction iron production method (hereinafter also referred to as DRI (Direct Reduction Iron)) is used as a raw material for blast furnaces or electric furnaces. When DRI is used as a substitute for scrap in electric furnaces, if the metallization rate of DRI is low, or the amount of gangue such as SiO ₂ or Al ₂ O ₃ is high, the unit energy consumption during electric furnace operation will increase, and the manufacturing cost will increase (such as non-patented products). Document 1). On the other hand, blast furnaces use unreduced iron ore, sinter and pellets with high gangue content. Therefore, even if DRI with low metallization rate or high gangue content is used, the specific energy consumption of the blast furnace is not will rise. It is better to replace iron ore, sinter and particles with DRI, so that the unit energy consumption will be reduced (for example, non-patent document 2).

Prior technical literature non-patent literature Non-patent literature 1: Joseph J Poveromo, 2013 World DRI & Pellet Congress, Abu Dhabi, DR Pellet Quality & MENA Applications Non-patent document 2: Kuniyo et al., Nippon Steel Technical Report No. 384, P.121-P.126

Summary of the invention The problem to be solved by the invention As mentioned above, if the amount of gangue in DRI is high, the unit energy consumption will increase when the electric furnace is used. Therefore, DR particles with a low gangue content are used in the direct reduction iron production method. DR pellets are produced from iron ore (concentrate) that has been enriched by magnetic beneficiation or gravity beneficiation. However, concentrates for DR pellets can only be produced from raw ore with excellent gangue separation properties produced in a specific area. .

Iron ore produced in Australia cannot be processed due to difficulty in gangue separation, resulting in a high gangue content. Furthermore, it is not limited to iron ore produced in Australia. In recent years, iron ore raw materials have gradually become inferior. Along with this, the amount of gangue in iron ore has increased, and we speculate that the production of DR particles will become more and more difficult in the future. In addition, including iron ore produced in Australia, low-quality iron ore contains a large amount of crystal water.

The present invention was made in view of the above-mentioned problems, and the purpose of the present invention is to provide a novel and improved iron-making method that can efficiently clump and reduce low-quality iron ore raw materials.

means to solve problems In order to solve the above-mentioned problems, the gist of this invention is as follows. (1) The iron-making method of aspect 1 of the present invention has the following steps: The ore beneficiation treatment step is to beneficiate high-crystalline iron ore with a ignition loss of 3 to 12 mass% to select at least a goethite-rich portion with an ignition loss of 4 mass% or more and an iron content of 55 mass% or more; The first agglomeration treatment step is to agglomerate the goethite-rich portion into first calcined particles in a pellet calcining furnace; and In the first reduction step, the first calcined particles are loaded into a shaft furnace at a surface temperature of not less than 600°C and the first calcined particles are directly reduced using a reducing gas containing more than 60 volume % hydrogen. In aspect 2 of the present invention, in the iron-making method of aspect 1, the first fired particles can be directly reduced to a metallization rate of 60% to 95%.

(3) Aspect 3 of the present invention can also be used in the iron-making method of Aspect 1 or 2. In the above-mentioned beneficiation treatment step, the ore can be further beneficiated to select red-rich iron with an ignition loss of less than 4 mass% and an iron content of more than 55 mass%. The iron ore part; and it further has a second agglomeration treatment step, which is to agglomerate the aforementioned hematite-rich part into second calcined particles in a particle calcining furnace.

(4) Aspect 4 of the present invention may further include a second reduction step in the iron-making method of aspect 3, which is to reduce the aforementioned second fired particles in a shaft furnace using hydrogen to an amount of 60% by volume or more. Gas is directly reduced to produce direct reduced iron with a metallization rate of more than 90%.

(5) Aspect 5 of the present invention can also be used in the iron-making method of any one of Aspects 1 to 4, and further has a water washing step, which is performed before the above-mentioned mineral processing step, from the above-mentioned highly crystalline ferrihydrite ore. Removal of tailings.

Invention effect According to the above aspect of the present invention, low-quality iron ore raw materials can be efficiently chunked and reduced.

Form used to implement the invention Hereinafter, this embodiment will be described in detail with reference to the drawings. In addition, the numerical range represented by "~" includes the values at both ends of "~". The percentage (%) of each component of iron ore in the text and tables refers to the mass % of iron ore relative to the total mass. Here, the iron content is measured in compliance with JIS M 8212: 2005 Iron Ore - Total Iron Content Quantitative Method. In addition, the crystal water content is regarded as the loss on ignition (LOI). Loss on ignition (LOI) is defined as the mass reduction ratio after holding iron ore at 1000°C for 60 minutes.

<1. Summary of this embodiment> The agglomeration method and reduction method of this embodiment are an iron production method that utilizes iron ore containing a large amount of crystal water, such as iron ore containing goethite produced in Australia, which has abundant reserves. In the iron-making method of this embodiment, the iron ore raw material is first separated into a goethite-rich portion mainly composed of goethite through an ore dressing process. During the mineral processing, it can also be separated into a hematite-rich part mainly composed of hematite, a goethite-rich part mainly composed of goethite, and a gangue-rich part mainly composed of gangue. Here, the hematite-rich part is a part with an LOI of less than 4 mass% and an iron content of 55 mass% or more, the goethite-rich part is a part with an LOI of 4 mass% or more and an iron content of 55 mass% or more, and the gangue-rich part is Parts with an iron content less than 55% by mass. The hematite-rich portion refers to the portion of highly crystallized ferrihydrite ore in which hematite is the main component, and is the portion of highly crystallized ferrihydrite ore with an LOI of less than 4 mass% and an iron content of more than 55 mass%. In addition, the so-called part with hematite as the main part refers to a part with a hematite content of more than 50% by mass relative to the total mass of the part. In addition, the goethite-rich part refers to the part of the highly crystallized ferrihydrite ore in which goethite is the main component, and is the part of the highly crystallized ferrihydrite ore with an LOI of 4% by mass or more and an iron content of 55% by mass or more. The so-called part with goethite as the main body means that the content of goethite is more than 50% by mass relative to the total mass of the part. The gangue-rich part refers to the part of the highly crystallized ferrihydrite ore in which gangue is the main part, and is the part of the highly crystallized ferrihydrite ore with an iron content of less than 55% by mass. The so-called part where gangue is the main body means that the content of gangue is more than 50% by mass relative to the total mass of the part. Next, by subjecting the hematite-rich portion and the goethite-rich portion to agglomeration and reduction processing respectively, the hematite-rich portion is processed into raw materials for electric furnaces, and the goethite-rich portion is processed into raw materials for blast furnaces.

The inventor used EDS (energy dispersive X-ray analysis) to analyze iron ore containing a large amount of crystal water (herein, LOI is regarded as its content) (hereinafter also referred to as "high crystallization water iron ore"), and The identification of mineral phases and the composition of each phase are analyzed. Here, high crystallization water iron ore refers to iron ore containing 3 to 12 mass% of crystallization water. That is, in this specification, the ignition loss of highly crystallized ferrihydrite is 3 to 12 mass%. The results revealed that highly crystallized ferrihydrite ore includes a hematite-rich part mainly composed of hematite, a goethite-rich part mainly composed of goethite, and a gangue-rich part mainly composed of gangue. Gangue components such as Si, Al, and P are mostly contained in the goethite-rich part and the gangue-rich part.

So the inventor came up with the following idea. That is, the high crystallization water iron ore is beneficiated according to specific gravity, and the divided parts are judged as to which of the hematite-rich part, the goethite-rich part, and the gangue-rich part belongs, and the hematite-rich part and the gangue-rich part are classified. The goethite part is individually agglomerated and reduced using appropriate methods. Here, since the hematite-rich part contains a large amount of iron, it is agglomerated into fired pellets and directly reduced in a shaft furnace to produce reduced iron. This can be effectively utilized as a raw material for electric furnaces with the same quality as conventional DR pellets. ; On the other hand, since the amount of iron in the goethite-rich portion is small, semi-reduced iron is produced and used as raw material for blast furnaces. By separating the high-crystalline ferrihydrite ore into a hematite-rich portion and a goethite-rich portion as described above, and then performing agglomeration and reduction treatment, the high-crystalline ferrihydrite ore can be efficiently produced into iron.

Here, compared to conventional fired particles derived from hematite or magnetite, fired particles derived from goethite-rich parts are inferior in strength or reduction powderability due to the influence of extraction of crystal water. , easily pulverized in the shaft furnace. If the particles are pulverized in the shaft furnace, the ventilation resistance will increase and the productivity of the shaft furnace will decrease. Not only that, it will also cause the iron oxide raw material to deteriorate, causing production obstacles. Therefore, in this embodiment, the fired particles derived from the goethite-rich portion are further preheated (or the temperature of the obtained high-temperature particles is maintained) and then charged into the shaft furnace. In this way, the thermal history experienced during the reduction process in the shaft furnace will be improved, and the above problems can be avoided.

In addition, the goethite-rich portion can also be used as a raw material for sinter. In this way, the aforementioned problems associated with using the particles produced from the goethite-rich portion in a shaft furnace can also be avoided.

＜2. Details of this embodiment＞ (2-1. Iron ore to be processed) Next, the details of the iron making method of this embodiment will be described. The iron ore (iron ore raw material) to be processed in this embodiment is the above-mentioned highly crystallized hydroiron ore. High crystal water iron ore contains 3 to 12 mass% of crystal water. Here, the mass % of crystal water is measured as loss on ignition (LOI). Most highly crystalline ferrihydrite ores contain 55 to 67 mass% iron. An example of highly crystallized ferric iron ore is Brockman ore, an Australian iron ore having the composition shown in Table 1.

The particle size of highly crystalline ferrihydrite ore is not particularly limited. The raw ore of highly crystallized hydroiron ore mined from veins is first coarsely crushed. When lump ore for blast furnaces is collected, it is crushed to a particle size of 50 mm or less, and the ore with a particle size of 50 mm to 10 mm is used as lump ore, and the particle size less than 10 mm is recovered as fine ore. The highly crystallized ferrihydrite ore used as the starting material in the embodiment of the present invention may be in a coarsely crushed state from which no lumps have been collected or in the form of powdered ore.

[Table 1]

(2-2. Steps of bulking method S10 and S10A) FIG. 1 shows the overall flow of the agglomeration method S10 and the reduction method S20 in the iron making method of this embodiment. FIG. 2 shows the overall flow of another block forming method S10A and reduction method S20A in the iron making method of this embodiment. The agglomeration method S10 includes a water washing process step S1, an ore dressing process step S2, and a first agglomeration process step S3B. The agglomeration method S10 may further include a sinter production step S4. The agglomeration method S10A, which also concentrates the hematite-rich portion into agglomerates, includes a water washing step S1, an ore beneficiation step S2, a first agglomeration step S3B, and a second agglomeration step S3A. The specific gravity separation method is used to separate the iron ore raw material, that is, high crystal water iron ore into plural components. Furthermore, the goethite-rich part was identified from the separated parts based on the iron content and LOI. It is also possible to determine which of the hematite-rich part, the goethite-rich part, and the gangue-rich part belongs to the separated parts based on the iron content and LOI. Here, the hematite-rich part is a part with an LOI of less than 4 mass% and an iron content of 55 mass% or more, the goethite-rich part is a part with an LOI of 4 mass% or more and an iron content of 55 mass% or more, and the gangue-rich part is Parts with an iron content less than 55% by mass. The separated goethite-rich fraction is processed into blocks according to the process shown in Figure 1. Each separated part can also be processed into blocks according to the process shown in Figure 2. In the second agglomeration process step S3A, the hematite-rich portion is agglomerated into second calcined particles in a pellet calcining furnace. In the first agglomeration process step S3B, the goethite-rich portion is agglomerated into first calcined particles in a pellet calcining furnace. In addition, the goethite-rich part can also be made into sinter using a sintering machine. The gangue-rich part depends on its iron content and can be discarded or used as raw material for sinter ore.

(2-2-1. Water washing treatment step) In the water washing step S1, it is advisable to perform water washing of the iron ore raw material before the mineral processing. Clay minerals (tailings) can be removed from highly crystallized iron ore through water washing treatment. Specifically, for example, iron ore raw materials are washed with water using a drum scrubber, a water washing screen, or the like. In this way, clay minerals (so-called tailings) with a particle size of 20 to 45 μm or less attached to the surface of the iron ore raw material can be washed away. Since the iron content of the tailings is low, it can be discarded.

[Table 2]

Table 2 shows an example of the results of the water washing treatment. As can be seen from Table 2, by removing clay minerals in advance, the iron content of the iron ore raw material can be increased and the gangue component can be reduced.

(2-2-2. Ore beneficiation treatment step) Next, in the ore beneficiation treatment step S2, the washed iron ore raw material is subjected to ore beneficiation treatment and separated into a plurality of parts. In the beneficiation treatment step S2, the high crystallization water iron ore is beneficiated to select at least a goethite-rich part with an iron content of at least 55% by mass. In the mineral processing step S2, the high crystal water iron ore can also be beneficiated to select a hematite-rich part with a loss on ignition LOI of less than 4 mass% and an iron content of 55 mass% or more, and a LOI of 4 mass% or more. A goethite-rich part with an iron content of more than 55% by mass. In the beneficiation treatment step S2, the highly crystallized iron ore can also be further beneficiated to select a gangue-rich portion with an iron content of less than 55% by mass. In addition, after analyzing the LOI and iron content of each separated part, it was determined which one belongs to the hematite-rich part, the goethite-rich part, and the gangue-rich part. Here, the specific gravity of each mineral phase is hematite: 5.3g/cm ³ , goethite: 3.8g/cm ³ , and gangue: 2.7g/cm ³ . Therefore, through the so-called specific gravity separation process (specific gravity separation process) ), and the iron ore raw material can be separated into a hematite-rich part, a goethite-rich part and a gangue-rich part. Magnetic beneficiation can also be carried out at the same time as specific gravity beneficiation.

First, the iron ore raw materials are classified with a particle size of about 3 mm. As for grading, it can be done through a sieve. The iron ore raw materials above and below the sieve can be separated by gravity using the following methods. Above the screen: Wave shock concentrator (JIG) or heavy liquid sorting Under the screen: Spiral, Up-current classifiers (UCC), Wet High Intensity Magnetic Separation (WHIMS) or heavy liquid sorting The reason for setting the classification particle size to 3 mm is that the particle size range that can be efficiently beneficiated by JIG is 3.0 mm or more, and the particle size range that can be efficiently classified by spiral is 3.0 mm or less. Below, an outline of each mineral processing method is explained.

(JIG) JIG is a type of specific gravity mineral processing, which uses differences in specific gravity to select mineral particles. Mineral particles are supplied to the particle layer with the net as the bottom. Then, let the water flow from bottom to top intermittently to raise the water level. In this way, mineral particles are rolled up in the water and temporarily suspended. Then, stop the water flow. In this way, when the water level drops and returns to its original state, the mineral particles will be deposited on the net again. When suspended in water and then deposited on the net again, the greater the specific gravity of the mineral particles, the faster the mineral particles will fall. Therefore, in the particle layer after deposition, the mineral particles with greater specific gravity will accumulate on the lower side. In this way, specific gravity can be used to concentrate mineral particles. That is, the desired mineral particles are extracted from each of the formed particle layers, whereby specific gravity can be used to select the mineral particles.

(spiral) Spiral is a type of specific gravity beneficiation process that utilizes the centrifugal force generated by the slurry (a mixture of water and mineral particles) flowing in a spiral groove. If the slurry is allowed to flow from the tower, as the slurry spirals down, the mineral particles with small specific gravity can be gathered on the outside by centrifugal force and separated from other mineral particles. High-density mineral particles that are less susceptible to centrifugal force are gathered on the inner periphery of the trench and removed. The mineral processing efficiency can be controlled by adjusting the ore feed size and the water volume in the trench.

(UCC) UCC is also a type of specific gravity mineral processing. In the UCC, the slurry (a mixture of water and mineral particles) is supplied from the upper part of the device, and the ascending water flow is supplied from the lower part. In addition, they will communicate and come into contact within the device. Since the mineral particles with small specific gravity will ride on the rising water flow, they can be separated from other mineral particles. Mineral particles with high specific gravity are less susceptible to rising water flow. Discharge from the bottom of the device. The mineral processing efficiency can be controlled by adjusting the size of the ore feed and the amount of water in the rising flow.

(WHIMS) WHIMS is a mineral processing method that utilizes magnetic force of 8,000 to 12,000 Gauss or more. A rotor that rotates and a magnet arranged in the rotor are disposed in the device. If the slurry (a mixture of water and mineral particles) is fed in the device, the non-magnetic particles will not adhere to the magnet, so they will fall directly and accumulate on the fixed plate at the bottom of the rotation. Paramagnetic particles are captured by high magnetic force and high gradient magnetic field, and are discharged at the weakened magnetic field while riding the rotation of the rotor. The strong magnetic particles will move by the rotation of the rotor and be discharged from the magnetic field.

(Heavy liquid sorting) Heavy liquid sorting is a type of specific gravity mineral processing. Heavy liquid sorting is also called heavy liquid ore dressing, heavy liquid coal sorting, floating and sinking sorting, etc. Heavy liquid sorting is a method that uses liquid (heavy liquid) with a specific gravity as a medium to separate useful minerals from waste rocks. Finely pulverize heavy liquid materials (magnetite, slag, barite, etc.) that have a specific gravity 2 to 3 times that of the produced heavy liquid, are hard and difficult to refine, have good chemical stability, and are easy to purify and recover, and Suspend it in water to make a heavy liquid. Mineral particles with higher specific gravity will sink into the heavy liquid, while mineral particles with low specific gravity will float above the heavy liquid, thereby separating the mineral particles with the desired specific gravity.

By appropriately adjusting the control conditions of the above-mentioned specific gravity beneficiation treatment (and magnetic beneficiation treatment), the iron ore raw material (high crystallization water iron ore) can be beneficiated to at least select an iron ore with a ignition loss LOI less than 4 mass% and an iron content of 55 mass%. % or more of hematite-rich part, and the goethite-rich part with LOI of 4 mass% or more and iron content of 55 mass% or more. The iron ore raw material can be separated into a hematite-rich part, a goethite-rich part and a gangue-rich part.

Table 3 below shows an example of the results of specific gravity separation of iron ore raw material (highly crystalline ferrihydrite ore) by UCC. As can be seen from Table 3, UCC can be used to separate iron ore raw materials into a hematite-rich part, a goethite-rich part, and a gangue-rich part.

[table 3]

(2-2-3. Particle manufacturing steps) Next, in the pellet production step, the goethite-rich portion and the hematite-rich portion are each agglomerated using a pellet firing furnace to prepare a raw material for direct reduction. In the second agglomeration process step S3A, the hematite-rich portion is agglomerated using a pellet sintering furnace. In the first agglomeration process step S3B, the goethite-rich portion is agglomerated using a pellet sintering furnace. The specific method of the particle manufacturing step is not particularly limited, as long as the general particle manufacturing method is followed. An example of the pellet production step is described in Non-Patent Document 3 (KOBE STEEL ENGINEERING REPORTS)/Vol.60 No.1 (Apr.2010). In this embodiment, the method described in this document is used To perform the particle manufacturing step, the manufacturing method is not limited to the method described in the non-patent document.

Table 4 shows an example of the composition of each particle. The fired particles (second fired particles) derived from the hematite-rich portion have a low gangue content, so they can be directly reduced and used as raw materials for electric furnaces. The fired particles (first fired particles) derived from the goethite-rich portion are not suitable as raw materials for electric furnaces due to their high gangue content, so they can be used as raw materials for blast furnaces. In Table 4, the goethite-rich particles refer to the first calcined particles, and the hematite-rich particles refer to the second calcined particles.

(2-2-4. Sinter production steps) In the sinter production step S4, the goethite-rich portion may be agglomerated using a sintering machine instead of the aforementioned pellet production step to produce raw materials for blast furnaces. Here, the conditions for producing sinter are not particularly limited. When the fired particles originating from the goethite-rich part are reduced, there may be problems with the strength and reduced powderability. This problem can be avoided by making sinter into blocks. Depending on its iron content, the gangue-rich part should be discarded or made into sintered ore using a sintering machine and lumped into blocks.

[Table 4]

(2-3. Restoration steps) The right side of Figure 1 shows the flow chart of the restoration steps. The restoration method S20 includes the first restoration step S5B. Reduction method S20 may also include blast furnace step S6. The reduction method S20A for further reducing the fired particles derived from the hematite-rich portion includes a first reduction step S5B and a second reduction step S5A. In the second reduction step S5A, the calcined particles (second calcined particles) derived from the hematite-rich portion are directly reduced using a shaft furnace to produce directly reduced iron with a metallization rate of 90% or more. The obtained direct reduced iron can be used as the raw material of reduced iron for electric furnaces. As the reducing gas, natural gas, synthesis gas (Syn-gas), H ₂ gas, etc. can be used. The reducing gas should contain more than 60% by volume of hydrogen. The operating conditions of the shaft furnace are as follows. In the electric furnace step S7, the reduced iron for electric furnaces produced in the second reduction step S5A is used to produce molten steel. ． Reducing gas temperature 700~1000℃. Reducing gas flow rate 1000~2200Nm ³ /t-DRI (flow rate per metric ton of reduced iron). Metalization rate: 90% or more Here, the metallization rate is defined as metallic iron concentration/total iron concentration × 100. The determination method of metallic iron concentration is standardized in ISO 5416 Bromomethanol titration method for determination of metallic iron in reduced iron. The total iron concentration is standardized in JIS M 8212: 2005 Iron Ore - Total Iron Quantitative Method.

In the first reduction step S5B, the calcined particles (first calcined particles) derived from the goethite-rich portion are charged into the shaft furnace at a surface temperature of the first calcined particles of 600°C or higher, and 60 volumes of hydrogen are used. % or more of reducing gas can be directly reduced. The upper limit of the surface temperature of the first fired particles is not particularly limited, but is, for example, 800°C. In the first reduction step S5B, the first fired particles can also be directly reduced to a semi-reduced state with a metallization rate of 60 to 95% to obtain semi-reduced fired particles. The optimal metallization rate after direct reduction is 60~90%. The so-called semi-reduced state refers to the state with a metallization rate of 60~95%. If the obtained semi-reduced fired particles have a high metallization rate, they can be used as raw materials for blast furnaces. Semi-reduced fired particles refer to fired particles with a metallization rate of 60% to 95%. As the reducing gas, natural gas, synthesis gas (Syn-gas), H ₂ gas, etc. can be used. The reducing gas should contain more than 60% by volume of hydrogen. The operating conditions of the shaft furnace are as follows. The upper limit of hydrogen gas is not particularly limited, for example, it is 100% by volume. ． Reducing gas temperature 700~1000℃. Reducing gas flow rate 1000~2200Nm ³ /t-DRI (flow rate per metric ton of reduced iron). Metalization rate 60%~95% Here, when the temperature of the fired particles (first fired particles) derived from the goethite-rich part is less than 600°C when loaded into the shaft furnace, the first fired particles are fired in the shaft furnace. The particles will be pulverized and the raw materials will be blocked in the shaft furnace, resulting in poor discharge. Therefore, the temperature of the first calcined pellets when loaded into the shaft furnace is 600°C or above. The temperature of the first fired pellets when loaded into the shaft furnace should be above 650°C. As mentioned above, the gangue-rich portion is lumped into sinter and is therefore suitable for use as a raw material for blast furnaces.

As described above, according to this embodiment, the hematite-rich part, the goethite-rich part, and the gangue-rich part are selected from the high-crystalline hydroiron ore, and then reduced by a method suitable for each. Therefore, low-quality iron ore raw materials can be efficiently reduced.

(2-4. Dust recycling) The dust or DRI powder generated by the iron-making method using direct reduction can be processed through the same route as the goethite-rich part. Dust or DRI powder has the effect of increasing the strength of particles. If used in low-strength goethite-rich particles, the strength can be improved.

(2-5. Others) In the blast furnace step S6, if the hematite-rich part or the goethite-rich part selected by the ore dressing treatment step has a particle size that can be used as lump ore in the blast furnace, this part can be directly used in the blast furnace; also The fired pellets originating from the goethite-rich portion can be charged directly into the blast furnace. Pig iron can be produced in blast furnace step S6. In the converter step S8, steel can be produced from the pig iron produced in the blast furnace step S6.

Example Next, examples of this embodiment will be described. In addition, the Example described below is an example of this invention, and this invention is not limited to the following Example.

(Example 1) In Example 1, the fired particles derived from the goethite-rich portion having the composition shown in Table 4 were charged into a shaft furnace to produce semi-reduced iron. Reducing gas is natural gas or synthetic gas. The manufacturing conditions are as follows. The raw material temperature is the temperature at which the pellets are fired when loaded into the shaft furnace. ． Raw materials used: Calcined particles derived from goethite-rich parts as described in Table 4 above. Raw material temperature 650℃. Reducing gas temperature 950℃. Reducing gas flow 1200Nm ³ /t-DRI． Metalization rate 82%. Product use: semi-reduced iron for blast furnace. The composition of the reducing gas is shown in Table 5 (Inlet) represents the input gas, and Outlet (Outlet) represents the composition of the output gas (exhaust gas). The numerical value of each component represents volume %. The Temp column recorded in Table 5 represents the input gas. (Inlet) temperature or output gas (Outlet) temperature (℃)

[table 5]

According to Example 1, semi-reduced iron with a metallization rate of 82% can be produced. As mentioned above, the semi-reduced iron derived from the goethite-rich portion contains a large amount of gangue components and is therefore suitable as a raw material for blast furnaces.

(Example 2) In Example 2, the fired particles derived from the hematite-rich portion having the composition shown in Table 4 were charged into a shaft furnace to produce reduced iron. Hydrogen is used as reducing gas. The manufacturing conditions are as follows. ． Raw materials used: rich hematite particles recorded in Table 4 above. Raw material temperature 650℃. Reducing gas temperature 1020℃. Reducing gas flow 1400Nm ³ /t-DRI． Metalization rate 94%. Product use: reduced iron for electric furnaces. The composition of the reducing gas is shown in Table 6 (Inlet) represents the input gas, and Outlet (Outlet) represents the composition of the output gas (exhaust gas). The numerical value of each component represents volume %. The Temp column recorded in Table 6 represents the input gas. (Inlet) temperature or output gas (Outlet) temperature (℃)

[Table 6]

According to Example 2, reduced iron with a metallization rate of 94% can be produced. As mentioned above, the reduced iron derived from the hematite-rich portion contains a small gangue component and is therefore suitable as a raw material for electric furnaces.

(Example 3) In Example 3, the fired particles derived from the goethite-rich portion having the composition shown in Table 4 were charged into a shaft furnace to produce semi-reduced iron. The reducing gas is hydrogen. The manufacturing conditions are as follows. ． Raw materials used: Calcined particles derived from goethite-rich parts as listed in Table 4. Raw material temperature 600℃. Reducing gas temperature 1050℃. Reducing gas flow 1250Nm ³ /t-DRI． Metalization rate 85%. Product use: semi-reduced iron for blast furnace. The composition of the reducing gas is shown in Table 7 (Inlet) represents the input gas, and Outlet (Outlet) represents the composition of the output gas (exhaust gas). The numerical value of each component represents volume %. The Temp column recorded in Table 7 represents the input gas. (Inlet) temperature or output gas (Outlet) temperature (℃)

[Table 7]

According to Example 3, semi-reduced iron with a metallization rate of 84% can be produced. As mentioned above, the semi-reduced iron derived from the goethite-rich portion contains a large amount of gangue components and is therefore suitable as a raw material for blast furnaces.

(Example 4) In Example 4, the fired particles derived from the goethite-rich portion having the composition shown in Table 4 were charged into a shaft furnace to produce semi-reduced iron. The reducing gas is hydrogen. The manufacturing conditions are as follows. ． Raw materials used: Calcined particles derived from goethite-rich parts as listed in Table 4. Raw material temperature 650℃. Reducing gas temperature 1020℃. Reducing gas flow 1580Nm ³ /t-DRI． Metalization rate 92%. Product use: semi-reduced iron for blast furnaces or reduced iron for electric furnaces. The composition of the reducing gas is shown in Table 8 (Inlet) represents the input gas, and Outlet (Outlet) represents the composition of the output gas (exhaust gas). The numerical value of each component represents volume %. The Temp column recorded in Table 8 represents the input gas. (Inlet) temperature or output gas (Outlet) temperature (℃)

[Table 8]

According to Example 4, semi-reduced iron with a metallization rate of 92% can be produced. As mentioned above, the semi-reduced iron derived from the goethite-rich portion contains a large amount of gangue components and is therefore suitable as a raw material for blast furnaces. On the other hand, since the metallization rate is high, it can also be used as reduced iron for electric furnaces.

(Example 5) In Example 5, the fired particles derived from the goethite-rich portion having the composition shown in Table 4 were charged into a shaft furnace to produce semi-reduced iron. The reducing gas is hydrogen. The manufacturing conditions are as follows. ． Raw materials used: Calcined particles derived from goethite-rich parts as listed in Table 4. Raw material temperature 620℃. Reducing gas temperature 980℃. Reducing gas flow 1700Nm ³ /t-DRI． Metalization rate 95%. Product use: semi-reduced iron for blast furnaces or reduced iron for electric furnaces. The composition of the reducing gas is shown in Table 9 (Inlet) represents the input gas, and Outlet (Outlet) represents the composition of the output gas (exhaust gas). The numerical value of each component represents volume %. The Temp column recorded in Table 9 represents the input gas. (Inlet) temperature or output gas (Outlet) temperature (℃)

[Table 9]

According to Example 5, semi-reduced iron with a metallization rate of 95% can be produced. As mentioned above, the semi-reduced iron derived from the goethite-rich portion contains a large amount of gangue components and is therefore suitable as a raw material for blast furnaces. On the other hand, since the metallization rate is high, it can also be used as reduced iron for electric furnaces.

Calcined pellets derived from the goethite-rich portion were charged into a shaft furnace at a raw material temperature of 550°C, and an attempt was made to produce reduced iron. However, the fired particles derived from goethite are pulverized in the shaft furnace, and the raw materials are clogged in the shaft furnace, resulting in poor discharge. From these circumstances, it can be seen that the raw material temperature when loading into the shaft furnace must be above 600°C.

The preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings. However, the present invention is not limited to the foregoing examples. It should be understood that those with ordinary knowledge in the technical field to which the present invention belongs can conceive various modifications or modifications within the technical scope of the present disclosure, and it should be understood that these also fall within the technical scope of the present invention.

S1: Water washing treatment step S2: Mineral processing steps S3A: Second chunking step S3B: 1st block processing step S4: Sinter manufacturing steps S5A: Second restoration step S5B: First restoration step S6: Blast furnace steps S7: Electric furnace steps S8: Converter step S10, S10A: Blocking method S20, S20A: Restoration method

FIG. 1 is a flow chart showing the procedures of the iron making method of this embodiment. FIG. 2 is a flow chart showing another procedure of the iron making method of this embodiment.

S1: Water washing treatment step S2: Mineral processing steps S3B: 1st block processing step S4: Sinter manufacturing steps S5B: First restoration step S6: Blast furnace steps S8: Converter step S10: Blocking method S20:Restore method

Claims (5)

An iron-making method characterized by the following steps: The ore beneficiation treatment step is to beneficiate high-crystalline iron ore with a ignition loss of 3 to 12 mass% to select at least a goethite-rich portion with an ignition loss of 4 mass% or more and an iron content of 55 mass% or more; The first agglomeration treatment step is to agglomerate the aforementioned goethite-rich portion into first calcined particles in a pellet calcining furnace; and In the first reduction step, the first calcined particles are loaded into a shaft furnace at a surface temperature of not less than 600°C and the first calcined particles are directly reduced using a reducing gas containing more than 60 volume % hydrogen. The iron making method of claim 1, wherein in the first reduction step, the first fired particles are directly reduced to a metallization rate of 60% to 95%. For example, the iron-making method of claim 1 is to further select the hematite-rich part with a ignition loss of less than 4% by mass and an iron content of more than 55% by mass in the aforementioned mineral processing step; and It further has a second agglomeration treatment step, which is to agglomerate the aforementioned hematite-rich portion into second calcined particles in a particle calcining furnace. For example, the iron-making method of claim 3 further includes a second reduction step, in which the aforementioned second fired particles are directly reduced in a shaft furnace using a reducing gas containing more than 60 volume % hydrogen to produce a metallization rate of more than 90%. Direct reduced iron. The iron-making method according to any one of claims 1 to 4 further includes a water washing step to remove tailings from the aforementioned high-crystalline ferrihydrite ore before the aforementioned mineral processing step.

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