JP5477170B2 - Method for producing sintered ore - Google Patents

Description

  The present invention relates to a method for producing a sintered ore used in a blast furnace using a DL-type sintering machine (dweroid-type sintering machine: hereinafter also abbreviated as “sintering machine”). The present invention relates to a method for producing high-quality sintered ore while efficiently recycling steelmaking slag generated in a steelmaking process in production to the production process of sintered ore.

A sintered ore used as an iron source in pig iron production operation by a blast furnace is generally manufactured by the following method. Of sintered ore raw material fine iron ore, a secondary raw material and carbonaceous material, and auxiliary materials, raw materials containing SiO _2, raw material containing CaO, etc. raw material containing MgO is hit, iron ore, coal This means raw materials other than wood and return ore.

  The carbonaceous material includes coke and coal, and means a raw material containing a free carbon source. In addition, dust, slag, etc. generated in steelworks are used as miscellaneous raw materials. These miscellaneous raw materials contain free carbon, but are classified as auxiliary raw materials. These individual raw materials are cut out from the raw material tank and mixed according to a pre-planned blending ratio. The mixed raw material is referred to as “sintered raw material”.

  Moisture is usually added to the sintered raw material so as to have a moisture value of about 6.0 to 7.5% by mass, and mixing, humidity conditioning and granulation are performed. In the process of adding moisture, mixing, conditioning and granulating, particles having various particle sizes are combined through moisture to form pseudo particles. The formed pseudo particles are referred to as “pseudo particles”. Usually, the pseudo particles are particles having a particle diameter of about 2 to 4 mm by using a raw material having a particle diameter of 1 mm or more as a core particle and a raw material having a particle diameter of 0.25 mm or less adhering to the periphery. .

  After the pseudo particles are charged into the surge hopper, the pseudo particles are cut from the lower side of the surge hopper by a roll feeder, and charged onto the pallet of the sintering machine through the sloping chute. The pseudo particles form a sintered raw material packed layer (hereinafter also abbreviated as “raw material layer”) on the pallet, and the layer thickness of the sintered raw material packed layer is usually adjusted to about 500 to 700 mm.

  The raw material layer thus formed is ignited on its surface in an ignition furnace of a sintering machine. By this ignition, combustion of the carbonaceous material in the pseudo particles existing in the raw material layer is started. The surrounding pseudo particles are heated by the combustion heat, the pseudo particles are partially melted, and the pseudo particles are cross-linked and sintered by the melt (melt), and the raw material layer is finally a sintered cake Form. The sintered cake formed in this manner is discharged from the discharge portion of the sintering machine, and is crushed to a predetermined particle size by a crusher to form a sintered ore, which is used as a raw material for the blast furnace.

  As described above, after the raw material layer is charged on the pallet of the sintering machine, a sintered cake is formed, and after cooling and before being discharged, the temperature rise, sintering reaction and cooling are performed. Since each operation is received, the quality of the sintered product depends on those conditions.

  Steelmaking slag may be used as a miscellaneous raw material when manufacturing a sintered ore, and this steelmaking slag is a by-product produced | generated by the steelmaking process in steel production. In addition to the raw materials for sintered ore, the steelmaking slag is considered to be reused (recycled) in the steelmaking process, landfill, or sold as various materials.

  Here, steelmaking slag means decarburization slag generated in a decarburization process such as a converter, desiliconization slag generated in a desiliconization process, desulfurization slag generated in a desulfurization process, dephosphorization slag generated in a dephosphorization process, Examples include secondary smelting slag generated in the secondary smelting process, continuous casting slag generated in the continuous casting process, and the like. Desiliconized slag, desulfurized slag, and dephosphorized slag are sometimes collectively referred to as hot metal pretreatment slag.

  In the steelmaking process, decarburization slag may be recycled in the dephosphorization process. However, since decarburization slag has a high melting point, it is difficult to recycle in a large amount in a dephosphorization furnace. In addition, when the steelmaking slag is landfilled, there are many environmental problems, so the amount of processing is limited. When steelmaking slag is sold externally as various materials, it is sold and used in the civil engineering and construction fields, but the amount received is small.

  On the other hand, when using steelmaking slag as a raw material of a sintered ore, the iron component and CaO component which are contained in steelmaking slag can be utilized effectively. Here, in the steelmaking process, a hot metal dephosphorization method in which a decarburization process is performed after the dephosphorization process may be used, and the decarburization slag generated in the decarburization process of the steelmaking process by the hot metal dephosphorization method is dephosphorized. Since it is generated from hot metal, the P content is low. The decarburization slag generated in the decarburization process of the steelmaking process by the hot metal dephosphorization method is referred to as “decarburization slag generated by the hot metal dephosphorization method”. By using the decarburized slag generated in the hot metal dephosphorization method as a raw material for sintered ore, it is possible to reduce the circulation of phosphorus in the processes from ironmaking to steelmaking.

Conventionally, steelmaking slag including decarburized slag generated by hot metal dephosphorization method has a high basicity (CaO / SiO ₂ ) which is a ratio of a fluorine content and a mass content of CaO and SiO ₂ . For this reason, since the fluidity | liquidity of the melt produced | generated is improved in the process which the pseudo | simulation particle | grains charged into the sintering machine burn and sinter, it was a raw material excellent in sinterability.

  Various proposals have heretofore been made with respect to methods for producing sintered ore using steelmaking slag. For example, there are Patent Documents 1 to 3. In the method for producing a sintered ore disclosed in Patent Document 1, a steelmaking slag containing 5 to 15% by weight of a FeO component and 0.5 to 4.0% by weight of a fluorine component is 0.1% of the total sintered raw material. This is a method for producing sintered ore containing ˜5.0% by weight and containing 6.0 to 12.0% by weight of CaO component. In the method for producing sintered ore described in Patent Document 1, the fluorine component of steelmaking slag is set to 0.5 to 4.0% by weight, so that sintering of iron ore and steelmaking slag is performed during the sintering process. It is said that the reaction can be kept appropriate.

Moreover, the manufacturing method of the sintered ore described in patent document 2 is a steelmaking slag to main raw material groups (henceforth A group), such as iron ore and coke, sintering raw materials, binders, such as quick lime, hematite type iron ore, and limestone. And the other group (hereinafter referred to as B group) to which dolomite is selectively added, the sintering raw materials belonging to Group A and Group B are mixed and granulated independently to form pseudo particles. This is a method for producing sintered ore using mixed raw materials. In the method for producing sintered ore described in Patent Document 2, granulation is performed by selectively combining dolomite having poor sinterability with steelmaking slag having excellent sinterability without reducing the quality of the sinter. In addition, dolomite that reduces the SiO ₂ content of sintered ore can be used.

  In the method for producing sintered ore described in Patent Document 3, high crystal hydrous ore containing 4% by mass or more of crystal water is blended by 40% by mass or more with respect to the total iron ore amount, and FeO is 5 to 30% by mass. A raw material in which the steelmaking slag contained is blended so that the mass% ratio (FeO / Fe) of FeO in the steelmaking slag to Fe in the high-crystal hydrous ore is 1.0% or more is a sintering raw material It is a manufacturing method of the sintered ore used as the whole quantity or one part. In the method for producing sintered ore described in Patent Document 3, when high crystalline hydrous ore is blended in the sintering raw material, the melting rate increases during the sintering process, and the fluidity of the melt deteriorates. It is supposed to be prevented by mixing steelmaking slag with the raw material.

  What is common to these Patent Documents 1 to 3 is that steelmaking slag has high fluorine content and basicity, so it can improve the melt fluidity during the sintering process and exhibit excellent sinterability. It is to maintain a proper sintering reaction by blending a steelmaking slag with a sintering raw material, and to exhibit excellent sinterability particularly when using a sintering raw material with inferior sinterability.

However, the current steelmaking process is shifted to an operation in which the amount of fluorine used is reduced in consideration of the influence on the environment, and the content of fluorine component in the steelmaking slag is 0.5% by mass or less. For this reason, the effect of improving the melt fluidity in the sintering process cannot be expected by mixing steelmaking slag with the sintering raw material and using a fluorine component such as CaF ₂ contained in the steelmaking slag.

JP 10-317070 A Japanese Patent Laid-Open No. 11-229046 Japanese Patent Laid-Open No. 2004-27250

Sumitomo Metals Vol. 42-4 (1990) p. 84-93 Japan Iron and Steel Institute Edition: Third Edition Steel Handbook II Steelmaking and Steelmaking (1979) p. 119

As described above, in recent years, in the steelmaking process, in consideration of the influence on the environment, so-called low fluorine operation that avoids the use of a solvent containing a large amount of fluorine such as CaF ₂ has been directed. The fluorine content of slag is decreasing. Furthermore, the basicity of the steelmaking slag also tends to decrease, and the melt fluidity is deteriorated from the viewpoint of steelmaking slag as a sintering raw material. Therefore, when steelmaking slag is used as a sintering raw material by a conventional blending method, productivity, product yield, and quality of the sintered ore are lowered.

  However, as mentioned above, steelmaking slag can be reused (recycled) in the steelmaking process, landfilled, or sold externally as various materials. However, there is a shortage in the amount that can be processed or used for the amount generated. ing. For this reason, in the processing of steelmaking slag, utilization as a sintering raw material is required as in the conventional case.

  The present invention has been made in view of such circumstances. When steelmaking slag having a low fluorine content and basicity and inferior melt fluidity is blended in a sintering raw material, the productivity of sintered ore is obtained. An object of the present invention is to provide a method for producing a sintered ore that can prevent deterioration of product yield and quality.

In order to solve the above problems, the present inventors conducted various tests and made extensive studies. As a result, by placing limestone close to the steelmaking slag, the molten CaO / Fe produced in the sintering process is obtained. ₂ O ₃ ratio (solid-liquid ratio) is raised, melt fluidity is improved, and easily meltable raw material (limestone) is placed in the vicinity of the heat generating raw material (steel slag). Liquid phase generation is promoted and melt fluidity is improved. As a result, it has been found that the melt fluidity can be ensured during the sintering process by suppressing the deterioration of the melt fluidity caused by blending steelmaking slag having a low fluorine content and basicity with the sintering raw material.

This invention is completed based on said knowledge, and makes the summary the manufacturing method of the sintered ore of following (1)-(4). In addition, the manufacturing method of the sintered ore shown in (1) of these is an invention as a reference example of the present invention.

(1) Mixing a sintering raw material containing a steelmaking slag and a limestone having a basicity which is a ratio of a mass content of CaO and SiO ₂ of not more than 0.5% by mass and a mass content of CaO and SiO ₂ , It is a method of granulating into pseudo particles and producing sintered ore using the pseudo particles, the sum of the steelmaking slag and the limestone content in the sintering raw material being 30 to 70% by mass, mass The manufacturing method of the sintered ore characterized by mix | blending limestone / steel-making slag which is content ratio 1 or more.

(2) The sintering raw material is divided into a group having a high CaO content (hereinafter referred to as A group) and a group having a low CaO content (hereinafter referred to as B group), and the sintering raw materials belonging to the A group and the B group are respectively independent. Are mixed and granulated into pseudo particles, and a sintered ore is produced using a mixed raw material in which pseudo particles of each group are mixed, and the fluorine component content is 0.5 mass% or less, and CaO and A steelmaking slag having a basicity which is a ratio of the mass content of SiO ₂ of 3.7 or less is used as the sintering raw material of the group A, and the content of the steelmaking slag and the limestone in the sintering raw material of the group A is as follows. The manufacturing method of the sintered ore characterized by mix | blending with limestone / steel-making slag which is 30-70 mass% of sum, and the ratio of mass content as 1 or more.

  (3) In the above (2), as the steelmaking slag, decarburization slag generated in the decarburization process is used in a steelmaking process by a hot metal dephosphorization method in which a decarburization process is performed on the hot metal after the dephosphorization process. The manufacturing method of the sintered ore as described.

  (4) The P content of the decarburized slag generated in the decarburization process of the steelmaking process by the hot metal dephosphorization method is 0.5% by mass or less. Production method.

  According to the method for producing a sintered ore of the present invention, when steelmaking slag having a low fluorine content and basicity and poor melt fluidity is blended with a sintering raw material, deterioration of melt fluidity can be suppressed, and the sintered ore can be suppressed. Productivity, product yield, and quality can be prevented.

It is a figure which shows the manufacturing process of the sintered ore performed in the Example.

  Below, the manufacturing method of the sintered ore of this invention is explained in full detail. In the method for producing a sintered ore of the present invention, either a method of blending steelmaking slag with the entire amount of sintered raw material or a method of blending steelmaking slag with a part of the sintered raw material can be used.

  When steelmaking slag is blended with the entire amount of sintered raw material, the method for producing sintered ore according to the present invention includes steelmaking slag and limestone having a fluorine content of 0.5% by mass or less and a basicity of 3.7 or less. Is a method of producing a sintered ore using the pseudo-particles by mixing and granulating the sintering raw material containing, and the sum of the steelmaking slag and limestone content in the sintering raw material is 30 It is characterized by blending with limestone / steel slag having a ratio of ˜70 mass% and mass content of 1 or more.

  When steelmaking slag is blended with some sintered raw materials, the method for producing sintered ore according to the present invention uses a group of high sintered CaO content (hereinafter referred to as Group A) and a group of low CaO content (hereinafter referred to as "O"). B group), and sintering raw materials belonging to group A and group B are mixed and granulated independently to form pseudo particles, and the sintered ore is mixed using the mixed raw materials in which the pseudo particles of each group are mixed. A steelmaking slag having a fluorine component content of 0.5% by mass or less and a basicity of 3.7 or less as a group A sintering raw material, and a steelmaking slag in the group A sintering raw material. The limestone / steel slag having a mass content ratio of 30 to 70% by mass is added to the sum of the limestone content and the limestone content.

  The split granulation method employed when steelmaking slag is blended with some sintered raw materials is a part of selective granulation processing technology in the production of sintered ore, and is described in Non-Patent Document 1, for example. The split granulation method divides the sintering raw material based on the fluidity of the melt in which the pseudo particles are partially melted during the sintering process and the content of the CaO component that plays an important role in the mineral formation of the sintered ore. In this process, the divided sintered raw materials are mixed and granulated independently to form pseudo particles, and pseudo particles having a high CaO component content and low pseudo particles are mixed and sintered.

  Such a divided granulation method is based on the premise that the CaO component is unevenly distributed, and the content of the CaO component with respect to the total amount of the sintered raw material needs to be within an appropriate range determined from the operating conditions of the blast furnace. In addition, when steelmaking slag is blended with some (group A) sintered raw materials, the group (group A) sintered raw materials having a high CaO content with respect to the total amount of the sintered raw materials is blended in an amount of 15 to 30% by mass. A ratio is desirable.

  When steelmaking slag is blended with the total amount or part (group A) of the sintered raw material, the sum of the steelmaking slag and limestone content in the total amount or part (group A) of the sintered raw material is 30 to 70% by mass. The reason why the limestone / steel slag, which is the ratio of the mass content, is set to 1 or more will be described.

  First, regarding the ratio of limestone / steel slag, when this mass content ratio is smaller than 1, limestone cannot be disposed in the vicinity of the steel slag. For this reason, since deterioration of the melt fluidity by mixing steelmaking slag having a low fluorine content and basicity into the sintering raw material cannot be suppressed, the productivity, product yield and quality of the sintered ore are lowered.

Here, limestone is a supply source of the CaO component having an important role in the production of sinter as described above, and is essential in the range of the component design of the sinter. On the other hand, steelmaking slag is a raw material that is optionally used as a raw material for sintered ore, and therefore a very small amount may be used. When a very small amount of steelmaking slag is used, the limestone / steelmaking slag ratio is a value that greatly exceeds 1 defined in the present invention, but even in that case, limestone is closely arranged around the steelmaking slag. As a result, the CaO / Fe ₂ O ₃ ratio (solid-liquid ratio) of the melt is increased during the sintering process, and the liquid phase generation by melting of limestone is promoted, so that the melt fluidity can be secured without problems. .

  Next, when the sum of the contents of steelmaking slag and limestone is less than 30% by mass, limestone is also present around raw materials other than steelmaking slag even when the ratio of limestone / steelmaking slag is 1 or more. Therefore, the effect of ensuring the melt fluidity during the sintering process cannot be fully enjoyed. On the other hand, if the sum of the steelmaking slag and limestone content is greater than 70% by mass, the total amount or a part of the sintering raw material is mixed, granulated, and as pseudo particles, the iron source contained in the pseudo particles is small, Since it is unevenly distributed, the effect of ensuring the melt fluidity during the sintering process cannot be fully enjoyed.

  In the method for producing a sintered ore of the present invention, the content of the fluorine component of the steelmaking slag is regulated to 0.5% by mass or less and the basicity is defined to be 3.7 or less. This is because steelmaking slag having a low basicity and inferior melt fluidity is used in the sintering raw material.

  As the steelmaking slag, the above-mentioned decarburization slag, desiliconization slag, desulfurization slag, dephosphorization slag, secondary smelting slag, continuous casting slag can be used. As the slag, it is desirable to use decarburized slag generated by hot metal dephosphorization. Since the decarburized slag generated in the hot metal dephosphorization process is a slag generated in the decarburization process applied after the dephosphorization process, the P content is low, and phosphorus circulates in the process from ironmaking to steelmaking. Can be reduced.

  When decarburization slag generated by hot metal dephosphorization is used as the steelmaking slag, it is desirable to use a decarburization slag generated by hot metal dephosphorization that has a P content of 0.5% by mass or less. This is because it is possible to further reduce the circulation of phosphorus in the process from ironmaking to steelmaking.

  In order to confirm the effect of the method for producing sintered ore according to the present invention, the following tests were conducted and the results were evaluated.

[Test method]
FIG. 1 is a diagram illustrating a manufacturing process of a sintered ore performed in an example. The sintering raw material is divided into a group A having a high CaO content and a group B having a low CaO content. As shown in FIG. 1, the sintering material belonging to the group A belongs to the group B by the first drum mixer 1a. The sintered raw materials were mixed and granulated independently in the second drum mixer 1b to form pseudo particles. The pseudo particles made of the sintering material belonging to Group A and the pseudo particles made of the sintering material belonging to Group B were mixed by the third drum mixer 1c to obtain a mixed material. Thereafter, the mixed raw material was charged into the sintering machine 2 to form a raw material layer, the raw material layer was burned to form a sintered cake, and the sintered cake was crushed to obtain a sintered ore.

The sintering machine uses a pallet area of 540 m ² (width 5.4 m, machine length 100 m), and is a decarburized slag generated by hot metal dephosphorization method as a steelmaking slag, and the content of fluorine component is 0.11 mass. % And basicity of 3.31 were used. Table 1 shows chemical components of the decarburized slag used in this example.

  In the example of the present invention, the content of decarburized slag in the sintered raw material of Group A is 8.6%, the content of limestone is 22.0%, and the sum of the steelmaking slag and the content of limestone is 30.6. The limestone / steel slag, which is the ratio of mass% and mass content, was mixed to 2.56. In Comparative Example 1, no decarburized slag (steel slag) was blended in any of the sintered raw materials of Group A and Group B. In Comparative Example 2, the decarburized slag was mixed with the sintered raw material of Group B instead of Group A. Table 2 shows the mixing ratio of each raw material with respect to the total amount of the sintered raw material, and Table 3 shows the mixing ratio of each raw material with respect to the sintering raw material of Group A or Group B.

  As shown in the subtotal column of Table 2, the blending ratio of the group (Group A) having a high CaO content ratio with respect to the total amount of the sintering raw material was slightly different in the present invention example or the comparative example, but was about 15% by mass.

[Evaluation index]
In both the inventive example and the comparative example, the production amount, product yield and quality of the sintered ore were evaluated. The amount of sintered ore produced (t / hr / m ² ) is the mass (t) of the sintered ore on the sieve obtained by crushing the sintered cake and sizing with a 5 mm sieve. The unit time is divided by the time (hr) and the pallet area (m ² ). The product yield (%) of sintered ore is obtained by dividing the mass of the sintered ore on the sieve obtained by crushing by the mass of the sintered cake before crushing, and expressing this ratio as a percentage. is there.

  Rotational strength (tumbler strength) was used as an index for evaluating the quality of sintered ore. Rotational strength (%) is obtained by putting the collected sintered ore having a particle diameter of 10 to 50 mm in a rotating drum having a diameter of 1 m and rotating it 200 times, and classifying with a sieve having a sieve diameter of 10 mm. This is a value obtained by dividing the mass of a certain sintered ore by the mass of the collected ore and expressing this ratio as a percentage. The rotational strength (tumbler strength) is described in Non-Patent Document 2, for example.

[Test results]
Table 4 shows the production amount, product yield, and quality of sintered ore as test results of the present invention and comparative examples.

Compared with Comparative Example 1 in which no decarburized slag was used and Comparative Example 2 in which decarburized slag was used in Group B, the inventive example improved the productivity, product yield and quality of the sintered ore. This is because the decarburized slag is added to the group A sintered raw material, so that the decarburized slag is arranged in a group having a high CaO content, and the melted CaO / Fe ₂ O ₃ (solid (Liquid ratio) increases, melt fluidity can be improved, and the easy-melting raw material (limestone) is placed near the heat-generating raw material (steel slag), which promotes liquid phase generation by melting limestone during the sintering process. The melt fluidity can be improved. This is because deterioration of the melt fluidity due to the blending of steelmaking slag having a low fluorine content and basicity into the sintering raw material was suppressed, and the melt fluidity could be secured during the sintering process.

  Therefore, the manufacturing method of the sintered ore of the present invention can suppress deterioration of melt fluidity when steelmaking slag having a low fluorine content and basicity is blended in the sintering raw material, and the productivity of the sintered ore can be suppressed. It was revealed that the product yield and the deterioration of quality can be prevented.

  According to the method for producing a sintered ore of the present invention, deterioration of melt fluidity can be suppressed when steelmaking slag having a low fluorine content and basicity and poor melt fluidity is blended in a sintering raw material. Productivity, product yield, and quality can be prevented.

  Therefore, by applying the present invention to the production of sintered ore used in a blast furnace, the fluorine content and basicity are low without lowering the productivity, product yield and quality of the sintered ore. Since the steelmaking slag having poor fluidity can be recycled, the steelmaking slag can be effectively used as a resource.

1a: 1st drum mixer, 1b: 2nd drum mixer,
1c: Third drum mixer, 2: Sintering machine

Claims (3)

The sintering raw material is divided into a group having a high CaO content (hereinafter referred to as A group) and a group having a low CaO content (hereinafter referred to as B group), and the sintering raw materials belonging to the A group and the B group are independently mixed, This is a method for producing sintered ore using a mixed raw material obtained by granulating into pseudo particles and mixing each group of pseudo particles, wherein the fluorine component content is 0.5% by mass or less, CaO and SiO ₂ A steelmaking slag having a basicity that is a mass content ratio of 3.7 or less is used as a sintering raw material of the group A, and the sum of the content ratios of the steelmaking slag and the limestone in the sintering raw material of the group A is 30. A method for producing a sintered ore characterized by blending with limestone / steel slag having a ratio of ˜70 mass% and a mass content of 1 or more. 2. The sintering according to claim 1 , wherein a decarburized slag generated in the decarburization process is used as the steelmaking slag in a steelmaking process by a hot metal dephosphorization method in which a decarburization process is performed on the hot metal after the dephosphorization process. Manufacturing method of ore. The method for producing a sintered ore according to claim 2 , wherein the P content of the decarburized slag generated in the decarburization step of the steelmaking step by the hot metal dephosphorization method is 0.5 mass% or less.

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