KR20240055010A - How to Season - Google Patents

Abstract

This iron making method includes a beneficiation treatment process of beneficiating highly crystalline water iron ore with an ignition loss of 3 to 12% by mass into a high-tight rich section with an ignition loss of at least 4% by mass or more and an iron content of 55% by mass or more, and transferring the high-tight rich section to a pellet kiln. A first agglomeration treatment step of agglomerating into a first fired pellet, charging the first fired pellet into a shaft furnace at a surface temperature of 600°C or higher of the first fired pellet, and reducing hydrogen to 60% by volume or more. It has a first reduction process, which is direct reduction using gas.

Description

How to Season

The present invention relates to a method of making iron. This application claims priority based on Patent Application No. 2021-159551 filed in Japan on September 29, 2021, and uses the content here.

As one of the iron-making methods for obtaining iron (reducing iron oxide) from raw materials containing iron oxide, the direct reduction iron-making method is known. The direct reduction ironmaking method has continued to develop against the backdrop of low construction costs for plants, ease of operation, and the ability to operate in small-scale plants. In particular, in the shaft furnace type direct reduction iron making method, various improvements have been made to effectively utilize the reducing gas in the furnace.

In addition, in recent years, with the aim of reducing carbon dioxide emissions from the steel industry, the development of a direct reduction iron making method using hydrogen as a reducing gas is in progress. As representative examples, HYBRIT and MIDREX+H ₂ are known, which use hydrogen obtained by electrolysis of water in a shaft furnace direct reduction iron making method.

Reduced iron (hereinafter also referred to as DRI (Direct Reduction Iron)) manufactured by the direct reduction iron making method is used as a raw material for blast furnaces and electric furnaces. When using DRI in an electric furnace as a replacement for scrap, 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 energy source unit during electric furnace operation increases, and the manufacturing cost increases (e.g. For example, non-patent document 1). On the other hand, since the blast furnace has a high amount of gangue and uses unreduced iron ore, sintered ore, and pellets, the energy source unit of the blast furnace does not increase even if DRI with a low metallization rate or a high amount of gangue is used. Rather, when iron ore, sintered ore, and pellets are replaced with DRI, the energy source unit decreases (for example, non-patent document 2).

Joseph J Poveromo, 2013 World DRI & Pellet Congress, Abu Dhabi, DR Pellet Quality & MENA Applications Kunitomo et al., Shinnittetsu Kibo No. 384, P.121-P.126

As mentioned above, if the amount of gangue in DRI is high, the energy source unit increases when used in an electric furnace. Therefore, in the direct reduction iron making method, DR pellets with a low amount of gangue are used. DR pellets are manufactured using iron ore (concentrate) as a raw material that has been enriched by magnetic beneficiation or specific gravity beneficiation, but DR pellet concentrates can only be manufactured from ore with good gangue separation properties produced from specific regions.

Australian iron ore is not beneficiated because it is difficult to separate the gangue, and as a result, the amount of gangue is high. In addition, not only iron ore from Australia, but also iron ore raw materials have been deteriorating in recent years. Along with this, the amount of iron ore gangue is increasing, and it is estimated that the production of DR pellets will become increasingly difficult in the future. Additionally, iron ore of inferior quality, including Australian iron ore, contains a lot of crystallized water.

The present invention was made in view of the above problems, and the object of the present invention is to provide a novel and improved iron making method capable of efficiently agglomerating and reducing low-quality iron ore raw materials.

In order to solve the above problems, the gist of the present invention is as follows.

(1) The iron making method of Embodiment 1 of the present invention includes a beneficiation treatment process of beneficiating high-crystal water iron ore with an ignition loss of 3 to 12% by mass into a high-tight rich section with an ignition loss of at least 4% by mass or more and iron content of 55% by mass or more; , a first agglomeration treatment step of agglomerating the high-tight rich portion into first fired pellets in a pellet kiln, and charging the first fired pellets into a shaft furnace at a surface temperature of 600° C. or higher of the first fired pellets, Direct reduction is performed using a reducing gas containing 60% by volume or more of hydrogen.

In mode 2 of the present invention, in the iron making method of mode 1, the first fired pellet may be directly reduced to a metallization rate of 60% to 95%.

(3) Embodiment 3 of the present invention is the iron making method of Embodiment 1 or 2, wherein in the beneficiation treatment step, a hematite rich portion having an ignition loss of less than 4% by mass and an iron content of 55% by mass or more is further beneficiated, and the hematite rich portion is further beneficiated, You may further include a second agglomeration treatment step of agglomerating the tight rich portion into second calcined pellets in a pellet kiln.

(4) Embodiment 4 of the present invention is the iron making method of Embodiment 3, wherein the second fired pellets are directly reduced using a reducing gas containing 60% by volume or more of hydrogen in a shaft furnace to form a direct reduction iron furnace with a metallization rate of 90% or more. You may further have a second reduction process.

(5) Embodiment 5 of the present invention may further include, in the steelmaking method of any one of Embodiments 1 to 4, a water washing treatment process for removing stray light from the high-crystal water iron ore before the mineral processing process.

According to the above aspect of the present invention, it becomes possible to efficiently agglomerate and reduce iron ore raw materials of poor quality.

1 is a flowchart explaining the procedures of the iron manufacturing method according to this embodiment.
Figure 2 is a flowchart explaining another procedure of the iron manufacturing method according to the present embodiment.

Hereinafter, this embodiment will be described in detail with reference to the drawings. In addition, the numerical range expressed using “to” includes the numerical values at both ends of “to”.

In the sentences, the percentage (%) of each component such as iron ore in the table means the mass % with respect to the total mass of iron ore or the like. Here, the measurement of iron content follows the JIS M 8212:2005 iron ore-electrode quantification method. Additionally, the loss of ignition (LOI) is considered to be the crystallization water content. Loss on Ignition (LOI) is the rate of mass reduction when iron ore is kept at 1000°C for 60 minutes.

<1. Overview of this embodiment>

The agglomeration method and reduction method according to the present embodiment are iron-making methods utilizing iron ore containing a large amount of crystal water, for example, Australian gothite-containing iron ore with abundant reserves. In the steelmaking method according to the present embodiment, the iron ore raw material is first separated into a high-tight rich portion mainly composed of high-tite through beneficiation. In the beneficiation treatment, it may be separated into a hematite-rich part mainly made of hematite, a gotite-rich part mainly made of gothite, and a gangue-rich part mainly made of gangue. Here, the hematite rich portion is a portion with an LOI of less than 4 mass% and 55 mass% or more of iron, the gotite-rich portion is a portion with an LOI of 4 mass% or more and 55 mass% or more of iron, and the gangue rich portion is a portion with an iron content of 55 mass% or more. It is a portion of less than mass%. The hematite-rich portion is a portion of the high-crystallized iron ore mainly composed of hematite, and refers to a portion of the high-crystallized iron ore with an LOI of less than 4 mass% and 55 mass% or more of iron. In addition, a site mainly composed of hematite refers to a site where the hematite content is 50% by mass or more relative to the total mass of the site. In addition, the high-crystallization rich portion refers to a portion of high-crystallization iron ore mainly composed of high-tite, and refers to a portion of high-crystallization iron ore with an LOI of 4 mass% or more and an iron content of 55 mass% or more. A site where gotite is the main component refers to a site where the content of gotite is 50% by mass or more relative to the total mass of the site. The gangue-rich portion is a portion of high-crystallized iron ore mainly composed of gangue, and refers to a portion of the high-crystallized iron ore containing less than 55% by mass of iron. A site mainly composed of gangue means that the content of gangue is 50% by mass or more with respect to the total mass of the site. Subsequently, the hematite rich portion and the high-tight rich portion are separately compacted and reduced to process the hematite rich portion into a raw material for an electric furnace, and the high-tite rich portion is processed into a raw material for a blast furnace.

The present inventor analyzed iron ore (hereinafter also referred to as “high crystal water iron ore”) containing a large amount of crystal water (herein, LOI is regarded as its content) by EDS (Energy Dispersive X-ray Spectrometry) to determine the mineral phase. Identification and composition of each phase were analyzed. Here, high crystal water iron ore refers to iron ore containing 3 to 12 mass% of crystal water. That is, in this specification, the loss on ignition of high-crystal water iron ore is 3 to 12 mass%. As a result, high-crystallized iron ore contains a hematite-rich part mainly made of hematite, a gotite-rich part mainly made of gothite, and a gangue-rich part mainly made of gangue, and most of the gangue components such as Si, Al, and P are gotite-rich. It became clear that it was present in the wealth and gangue rich areas.

Accordingly, the present inventor obtained the following idea. That is, a method in which high-crystallized iron ore is processed for beneficiation based on specific gravity, and whether the divided region is a hematite-rich region, a gotite-rich region, or a gangue-rich region is determined, and the hematite-rich region and the go-tite-rich region are suitable for each. It is separately compacted and reduced. Here, since the hematite rich portion contains a lot of iron, it can be effectively utilized as a raw material for electric furnaces with the same quality as conventional DR pellets by compacting it into fired pellets and directly reducing it to reduced iron in a shaft furnace. Since the high-tight rich part has relatively little iron, it is used as semi-recycled iron and as a raw material for blast furnaces. As described above, high-crystal-number iron ore can be efficiently manufactured by separating the high-crystal-number iron ore into a hematite-rich portion and a high-crystal-rich portion and then agglomerating and reducing it.

Here, compared to conventional fired pellets derived from hematite or magnetite, the fired pellets derived from the gotite-rich portion are inferior in terms of strength and reduction differentiation ability due to the influence of the departure of crystal water, and are prone to differentiation within the shaft furnace. . When pellets are differentiated in the shaft furnace, ventilation resistance increases, which not only reduces productivity in the shaft furnace, but also causes poor drop of iron oxide raw materials, resulting in production failure. Therefore, in this embodiment, the fired pellets derived from the high-tight rich portion are charged into the shaft furnace after further preheating (or while maintaining the high temperature of the produced pellets). As a result, the heat history received during the reduction process in the shaft furnace is improved, and the above-mentioned problems can be avoided.

Additionally, the high-tite rich portion may be used as a raw material for sintered ore. This also avoids the above-mentioned problems accompanying the use of pellets made from high-tight rich portions as shafts.

<2. Details of this embodiment>

(2-1. Iron ore to be processed)

Next, details of the iron making method according to this embodiment will be described. The iron ore (iron ore raw material) subject to processing in this embodiment is the high crystalline water iron ore described above. 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). High-crystal-number iron ore often contains 55 to 67% by mass of iron. An example of a high-crystal number iron ore is Brockman ore, an Australian iron ore having the components shown in Table 1.

The particle size of high-crystalline iron ore is not particularly limited. The highly crystalline iron ore mined from the vein is first roughly crushed. When collecting lump ore for a blast furnace, it is pulverized to a particle size of 50 mm or less, and the particle size of 50 mm to 10 mm is recovered as lump ore, and the particle size of less than 10 mm is recovered as spectrometry. The high-crystal water iron ore used as the starting material for the embodiment of the present invention may be in a coarsely pulverized state without collecting lump ore or in a fine-grained state.

(2-2. Process of compaction method S10, S10A)

FIG. 1 shows the overall flow of agglomeration method S10 and reduction method S20 in the iron manufacturing method according to this embodiment. FIG. 2 shows the overall flow of other agglomeration method S10A and reduction method S20A in the iron manufacturing method according to the present embodiment. Agglomeration method S10 includes water washing treatment process S1, beneficiation treatment process S2, and first agglomeration treatment process S3B. The agglomeration method S10 may further include the sintered ore manufacturing process S4. Agglomeration method S10A, which agglomerates the hematite rich portion by beneficiation, includes water washing process S1, beneficiation treatment process S2, first agglomeration treatment process S3B, and second agglomeration treatment process S3A.

Highly crystalline iron ore, which is a raw material for iron ore, is separated into condensate using a specific gravity separation method. Then, the separated portion is identified from the iron content and LOI of the high-tight rich portion. It may be determined from the iron content and LOI whether the separated portion is a hematite-rich portion, a gothite-rich portion, or a gangue-rich portion. Here, the hematite rich portion is a portion with an LOI of less than 4 mass% and 55 mass% or more of iron, the gotite-rich portion is a portion with an LOI of 4 mass% or more and 55 mass% or more of iron, and the gangue rich portion is a portion with an iron content of 55 mass% or more. It is a portion of less than mass%.

The separated high-tite rich portion is subjected to compaction processing according to the flow in FIG. 1. Each separated part may be separately compacted according to the flow of FIG. 2 . In the second agglomeration treatment step S3A, the hematite rich portion is agglomerated into second fired pellets in a pellet kiln. In the first agglomeration treatment step S3B, the high-tite rich portion is agglomerated into first fired pellets in a pellet kiln. Additionally, the gotite rich portion may be used as a sintering ore. Depending on its iron content, the gangue rich part is preferably disposed of or used as a raw material for sintered ore.

(2-2-1. Water washing process)

In the water washing process S1, it is preferable to wash the iron ore raw material prior to the mineral processing. By water washing treatment, clay minerals (tailings) can be removed from high-crystal water iron ore. Specifically, for example, the iron ore raw material is washed with a drum type scrubber or a washing sieve. As a result, clay minerals (so-called tailings) with a particle size of 20 to 45 μm or less adhering to the surface of the iron ore raw material can be washed away. The stray light is low in iron, so it is best to discard it.

An example of the results of the water washing treatment is shown in Table 2. As is clear 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. Mineral processing process)

Subsequently, in beneficiation process S2, the washed iron ore raw material is subjected to beneficiation treatment and is separated into a plurality of parts. In beneficiation process S2, high-crystal water iron ore is beneficiated in a high-tite rich section containing at least 55% by mass of iron. In beneficiation process S2, high-crystallized iron ore is beneficiated into a hematite-rich portion with a loss-on-ignition LOI of less than 4% by mass and iron content of 55% by mass or more, and a high-tight rich portion with an illumination loss LOI of 4% by mass or more and iron content of 55% by mass or more. You can do it. In the beneficiation process S2, the high-crystal water iron ore may be further beneficiated in a gangue rich section with an iron content of less than 55% by mass. Then, the LOI and iron content of each separated part are analyzed to determine which of the hematite-rich part, gothite-rich part, and gangue-rich part it belongs to. Here, the specific gravity of each mineral phase is hematite: 5.3 g/cm3, gothite: 3.8 g/cm3, and gangue: 2.7 g/cm3, so the iron ore raw material is separated into the hematite rich section by so-called specific gravity beneficiation treatment (gravity separation treatment). , it can be separated into a gotite rich part, and a gangue rich part. Magnetic beneficiation may be performed together with specific gravity beneficiation.

First, the iron ore raw material is classified to a particle size of about 3 mm. Classification can be done through a sieve. It is recommended that the iron ore raw materials above and below the sieve be subjected to specific gravity beneficiation using the following methods.

Sieve phase: JIG or heavy liquid screening

Sieve: Spiral, Up-current classifiers (UCC), Wet High Intensity Magnetic Separation (WHIMS) or heavy liquid screening

The reason for setting the classification particle size to 3 mm is that the particle size range that can be efficiently classified 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. Hereinafter, an outline of each mineral processing method will be described.

(JIG)

JIG is a type of specific gravity beneficiation treatment and is a method of selecting mineral particles using differences in specific gravity. Mineral particles are fed into a particle bed with a mesh bottom. Next, water is intermittently flowed from bottom to top to raise the water level. As a result, the mineral particles are pulled up into the water and temporarily float. Then stop the water flow. As a result, while the water level goes down and returns to its original state, the mineral particles settle on the network again. When floating in water and settling again on the net, the larger the specific gravity of the mineral particles, the faster the mineral particles fall. Therefore, in the particle layer after sedimentation, mineral particles with a larger specific gravity gather at the bottom. By doing this, mineral particles can be concentrated according to specific gravity. That is, by extracting the desired mineral particles from each formed particle layer, the mineral particles can be selected according to specific gravity.

(spiral)

Spiral is a type of specific gravity beneficiation treatment, and is a beneficiation method that utilizes the centrifugal force generated in the slurry (a mixture of water and mineral particles) flowing in a spiral-shaped trough. When slurry flows from the top of the tower, while the slurry goes down the spiral, mineral particles with a small specific gravity gather on the outside due to centrifugal force and can be separated from other mineral particles. High-specific gravity mineral particles that are less susceptible to centrifugal force gather on the inner periphery of the gutter and are extracted. The light beneficiation efficiency is controlled by adjusting the feed size and water quantity in the trough.

(UCC)

UCC is also a type of specific gravity beneficiation treatment. In UCC, slurry (a mixture of water and mineral particles) is supplied from the top of the device, and an upward water flow is supplied from the bottom. Also, since they interact and come into contact within the device, and mineral particles with a small specific gravity ride the rising water current, they can be separated from other mineral particles. Mineral particles with high specific gravity are less susceptible to the influence of rising water flow and are discharged from the bottom of the device. The beneficiation efficiency is controlled by adjusting the feed size and quantity of rising water flow.

(WHIMS)

WHIMS is a beneficiation method using magnetic force of 8000 to 12000 gauss or more. Inside the device, a rotating rotor and a magnet disposed within the rotor are disposed. When slurry (a mixture of water and mineral particles) is fed into the device, the non-magnetic particles do not stick to the magnet, so they fall and are collected on a fixed tray at the rotating bottom. Paramagnetic particles are replenished by high magnetic force and high gradient magnetic fields, and are discharged from locations where magnetism is weakened through rotor rotation. Ferromagnetic particles move through the rotation of the rotor and are discharged from a location away from the magnetic field.

(Heavy liquid screening)

Heavy liquid selection is a type of specific gravity beneficiation treatment. Heavy liquid sorting is also referred to as heavy liquid beneficiation, heavy liquid coal selective, and fluctuating sorting. Heavy liquid sorting is a method of separating useful minerals and waste rock using a liquid (heavy liquid) with a high specific gravity as a medium. Heavy liquid materials (magnetite, slag, barite, etc.), which have a specific gravity 2 to 3 times that of the produced heavy liquid, are hard and difficult to refine, and have good chemical stability and are easy to purify and recover, are finely ground and suspended in water to obtain a heavy liquid. Lose. Mineral particles with a higher specific gravity than the heavy liquid sink in the heavy liquid, and mineral particles with a low specific gravity float on the upper surface of the heavy liquid, thereby separating mineral particles of the desired specific gravity.

By appropriately adjusting the control conditions of the above-described specific gravity beneficiation (and magnetic beneficiation), the iron ore raw material (high crystalline water iron ore) has at least an ignition loss LOI of less than 4% by mass and a hematite rich portion with an iron content of 55% by mass or more. It can be beneficiated in a high-tite rich portion with an LOI of 4% by mass or more and an iron content of 55% by mass or more. The iron ore raw material can be separated into a hematite rich part, a gothite rich part, and a gangue rich part.

An example of the results of specific gravity separation of iron ore raw material (high crystalline water iron ore) by UCC is shown in Table 3 below. As is clear from Table 3, the iron ore raw material can be separated into a hematite rich portion, a gothite rich portion, and a gangue rich portion by UCC.

(2-2-3. Pellet manufacturing process)

Subsequently, in the pellet manufacturing process, the gotite-rich portion and the hematite-rich portion are separately agglomerated using a pellet calcination furnace to serve as raw materials for direct reduction. In the second agglomeration treatment step S3A, the hematite rich portion is agglomerated using a pellet calcination furnace. In the first agglomeration treatment process S3B, the high-tite rich portion is agglomerated using a pellet calcination furnace. The specific method of the pellet manufacturing process is not particularly limited, and may be performed according to a general pellet manufacturing method. An example of the pellet manufacturing process is described in Non-Patent Document 3 (KOBE STEEL ENGINEERING REPORTS/Vol.60 No.1 (Apr. 2010). In this embodiment, the pellet manufacturing process is performed by the method described in the document. However, the manufacturing method is not limited to the method described in this non-patent document.

An example of the composition of each pellet is shown in Table 4. Since the fired pellets (second fired pellets) derived from the hematite rich portion have a low gangue content, they can be directly reduced and used as a raw material for an electric furnace. The fired pellets (first fired pellets) derived from the high-tight rich portion have a relatively high gangue content and are not suitable as raw materials for electric furnaces, so they can be used as raw materials for blast furnaces. In Table 4, the gotite rich pellets mean the first fired pellets, and the hematite rich pellets mean the second fired pellets.

(2-2-4. Sintered ore manufacturing process)

In the sintered ore manufacturing process S4, the high-tight rich portion may be compacted using a sintering machine instead of the pellet manufacturing process described above, and may be used as a raw material for a blast furnace. Here, conditions during production of sintered ore are not particularly limited. The fired pellets derived from the high-tight rich portion may have problems with strength and reduction differentiation during reduction. That problem can be avoided by compacting it as a sintered ore.

Depending on its iron content, it is preferable to discard the gangue rich portion or agglomerate it as sintered ore in a sintering machine.

(2-3. Reduction process)

A flow chart of the reduction process is shown on the right side of Figure 1. Reduction method S20 includes a first reduction step S5B. Reduction method S20 may include blast furnace step S6. The reduction method S20A, which further reduces the calcined pellet 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 fired pellets (second fired pellets) derived from the hematite rich portion are directly reduced using a shaft furnace to obtain directly reduced iron with a metallization rate of 90% or more. The obtained directly reduced iron can be used as a reduced iron raw material for an electric furnace. As the reducing gas, natural gas, synthetic gas (Syn-gas), H ₂ gas, etc. can be used. The reducing gas preferably contains 60% by volume or more of hydrogen gas. The operating conditions for the shaft furnace are, for example, as follows. In the electric furnace step S7, molten steel is obtained using the reduced iron for electric furnaces obtained in the second reduction step S5A.

·Reduction gas temperature 700 to 1000℃

·Reduction gas flow rate 1000 to 2200 Nm ³ /t-DRI (flow rate per ton of reduced iron)

·Metalization rate of 90% or more

Here, the metallization rate is defined as metallic iron concentration/total iron content × 100. The method for measuring metallic iron concentration is specified in ISO 5416 bromethanol titration method for measuring metallic iron in reduced iron. The concentration of electro-iron is specified in JIS M 8212:2005 Iron ore-electrode quantification method.

In the first reduction step S5B, fired pellets (first fired pellets) derived from the high-tight rich portion are charged into the shaft furnace at a surface temperature of 600°C or higher of the first fired pellet, and a reducing gas containing 60% by volume or more of hydrogen is added. Use it to directly reduce it. The upper limit of the surface temperature of the first fired pellet is not particularly limited, and is, for example, 800°C. In the first reduction step S5B, the first fired pellet may be directly reduced to a semi-reduced state with a metallization rate of 60 to 95% to obtain a semi-reduced fired pellet. A more preferable metallization rate after direct reduction is 60 to 90%. The semi-reduced state refers to a state with a metallization rate of 60 to 95%. The obtained semi-reduced fired pellets can be used as a raw material for a blast furnace if the metallization rate is high. Semi-reduction fired pellets refer to fired pellets with a metallization rate of 60% to 95%. As the reducing gas, natural gas, synthetic gas (Syn-gas), H ₂ gas, etc. can be used. The reducing gas preferably contains 60% by volume or more of hydrogen gas. The operating conditions for the shaft furnace are, for example, as follows. The upper limit of hydrogen gas is not particularly limited, and is, for example, 100 volume%.

·Reduction gas temperature 700 to 1000℃

·Reduction gas flow rate 1000 to 2200 Nm ³ /t-DRI (flow rate per ton of reduced iron)

·Metalization rate 60% to 95%

Here, when the temperature of the fired pellets (first fired pellets) derived from the high-tight rich portion when charging into the shaft furnace is less than 600°C, the first fired pellets are differentiated within the shaft furnace, and The raw material is blocked, resulting in poor discharge. Therefore, the temperature of the first fired pellet when charged into the shaft furnace is 600°C or higher. The temperature of the first fired pellet when charged into the shaft furnace is preferably 650°C or higher.

Since the gangue rich portion is agglomerated as sintered ore as described above, it is preferable to use it as a raw material for a blast furnace.

As described above, according to the present embodiment, high-crystal water iron ore is beneficiated in a hematite-rich section, a gotite-rich section, and a gangue-rich section, and is reduced by a method suitable for each. Therefore, it becomes possible to efficiently reduce iron ore raw materials of inferior quality.

(2-4. Dust recycling)

It is recommended that dust and DRI powder generated from the direct reduction steelmaking method be processed through the same route as the high-tight rich section. Dust or DRI powder has the effect of improving the strength of pellets, and can improve the strength when used in low-strength high-tight rich pellets.

(2-5. Others)

In the blast furnace step S6, among the hematite rich portion or high-tight rich portion beneficiated in the mineral processing step, the portion having a particle size that can be used as lump ore in the blast furnace may be used directly in the blast furnace, and fired pellets derived from the high-tite rich portion may be used. You can charge it directly into the blast furnace. In blast furnace process S6, pig iron can be obtained. In the converter process S8, steel can be obtained from the pig iron obtained in the blast furnace process S6.

Example

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

(Example 1)

In Example 1, fired pellets derived from the high-tight rich portion with the composition shown in Table 4 were charged into a shaft furnace to produce semi-recycled iron. Natural gas or synthetic gas was used as the reducing gas. Manufacturing conditions are as follows. The raw material temperature is the temperature of the fired pellets when charged into the shaft furnace.

· Raw materials used: fired pellets derived from the Gotite rich portion listed in Table 4 above

·Raw material temperature 650℃

·Reduction gas temperature 950℃

·Reduction gas flow rate 1200Nm ³ /t-DRI

·Metalization rate 82%

·Use of product: Recycled iron for blast furnace use

Composition of the reducing gas is as shown in Table 5 (Inlet indicates the composition of the input gas, Outlet indicates the composition of the output gas (exhaust gas). The numerical value of each component indicates volume%. The Temp column in Table 5 indicates the composition of the input gas. (Inlet temperature or output gas (Outlet) temperature (℃))

According to Example 1, semi-recovered iron with a metallization rate of 82% could be produced. As described above, the semi-recovered iron derived from the gotite 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, fired pellets derived from the hematite rich portion with the composition shown in Table 4 were charged into a shaft furnace to produce reduced iron. Hydrogen gas was used as a reducing gas. Manufacturing conditions are as follows.

· Raw materials used: Hematite rich pellets listed in Table 4 above

·Raw material temperature 650℃

·Reduction gas temperature 1020℃

·Reduction gas flow rate 1400Nm ³ /t-DRI

·Metalization rate 94%

·Use of product Reduced iron for electric furnace

Composition of the reducing gas is as shown in Table 6 (Inlet indicates the composition of the input gas, Outlet indicates the composition of the output gas (exhaust gas). The numerical value of each component indicates volume%. The Temp column in Table 6 indicates the composition of the input gas. (Inlet temperature or output gas (Outlet) temperature (℃))

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

(Example 3)

In Example 3, fired pellets derived from the high-tight rich portion with the composition shown in Table 4 were charged into the shaft furnace to produce semi-recycled iron. Hydrogen was used as a reducing gas. Manufacturing conditions are as follows.

· Raw materials used: fired pellets derived from the Gotite rich portion listed in Table 4

·Raw material temperature 600℃

·Reduction gas temperature 1050℃

·Reduction gas flow rate 1250Nm ³ /t-DRI

·Metalization rate 85%

·Use of product: Recycled iron for blast furnace use

Composition of the reducing gas is as shown in Table 7 (Inlet indicates the composition of the input gas, Outlet indicates the composition of the output gas (exhaust gas). The numerical value of each component indicates volume%. The Temp column in Table 7 indicates the composition of the input gas. (Inlet temperature or output gas (Outlet) temperature (℃))

According to Example 3, semi-recovered iron with a metallization rate of 84% could be produced. As described above, the semi-recovered iron derived from the gotite 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, fired pellets derived from the high-tight rich portion with the composition shown in Table 4 were charged into the shaft furnace to produce semi-recycled iron. Hydrogen was used as a reducing gas. Manufacturing conditions are as follows.

· Raw materials used: fired pellets derived from the Gotite rich portion listed in Table 4

·Raw material temperature 650℃

·Reduction gas temperature 1020℃

·Reduction gas flow rate 1580Nm ³ /t-DRI

·Metalization rate 92%

·Product usage: Reduced iron for blast furnaces, or reduced iron for electric furnaces

Composition of the reducing gas is as shown in Table 8 (Inlet indicates the composition of the input gas, Outlet indicates the composition of the output gas (exhaust gas). The numerical value of each component indicates volume%. The Temp column in Table 8 indicates the composition of the input gas (exhaust gas). (Inlet temperature or output gas (Outlet) temperature (℃))

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

(Example 5)

In Example 5, fired pellets derived from the high-tight rich portion with the composition shown in Table 4 were charged into the shaft furnace to produce semi-recycled iron. Hydrogen was used as a reducing gas. Manufacturing conditions are as follows.

· Raw materials used: fired pellets derived from the Gotite rich portion listed in Table 4

·Raw material temperature 620℃

·Reduction gas temperature 980℃

·Reduction gas flow rate 1700Nm ³ /t-DRI

·Metalization rate 95%

·Product usage: Reduced iron for blast furnaces, or reduced iron for electric furnaces

Composition of the reducing gas is as shown in Table 9 (Inlet indicates the composition of the input gas, Outlet indicates the composition of the output gas (exhaust gas). The numerical value of each component indicates volume%. The Temp column in Table 9 indicates the composition of the input gas. (Inlet temperature or output gas (Outlet) temperature (℃))

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

An attempt was made to produce reduced iron by charging fired pellets derived from the high-tight rich portion into a shaft furnace at a raw material temperature of 550°C. However, the fired pellets derived from gotite were differentiated in the shaft furnace, and the raw material was blocked in the shaft furnace, resulting in poor discharge. From these, it was found that the temperature of the raw material when charging into the shaft furnace needs to be 600°C or higher.

Although preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person with ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea of the present disclosure, and of course, the present invention also applies to these. It is understood that it falls within the technical scope of.

Claims (5)

A beneficiation treatment process of beneficiating highly crystalline water iron ore with an ignition loss of 3 to 12% by mass to a high-tight rich section with an ignition loss of at least 4% by mass or more and iron content of 55% by mass or more;
A first agglomeration treatment process of agglomerating the high-tight rich portion into first fired pellets in a pellet kiln,
A first reduction process in which the first fired pellet is charged into a shaft furnace at a surface temperature of 600°C or higher of the first fired pellet, and directly reduced using a reducing gas containing 60% by volume or more of hydrogen.
A steelmaking method characterized by having a. According to paragraph 1,
In the first reduction process, the first fired pellet is directly reduced to a metallization rate of 60% to 95%. According to paragraph 1,
In the above beneficiation treatment step, the hematite rich portion having an ignition loss of less than 4% by mass and an iron content of 55% by mass or more is further beneficiated,
A steelmaking method characterized by further comprising a second agglomeration treatment step of agglomerating the hematite rich portion into second calcined pellets in a pellet kiln. According to clause 3,
An iron making method characterized by further comprising a second reduction step in which the second fired pellets are directly reduced in a shaft furnace using a reducing gas containing 60% by volume or more of hydrogen to obtain directly reduced iron with a metallization rate of 90% or more. According to any one of claims 1 to 4,
An iron making method characterized by further comprising a water washing treatment process for removing stray iron ore from the high-crystal water iron ore before the mineral beneficiation treatment process.

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