JP2007291455A - Method for manufacturing sintered ore - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing sintered ore by which, even when the content of components forming blast furnace slag is lower than before, a shatter strength of ≥90% and a reduction degradation impellent of ≤35% can be maintained and deterioration in reducibility index can be prevented. <P>SOLUTION: Blended raw materials consisting of iron source materials containing at least iron ore fines, auxiliary raw materials and a carbonaceous material, are mixed and pelletized with the addition of water, and the resulting pellets are supplied to a sintering machine, where the carbonaceous material is burned, melted and cooled to manufacture sintered ore containing 4.0 to 5.0 mass% SiO<SB>2</SB>and 7 to 9 mass% CaO. In this process, the method for manufacturing sintered ore is characterized in that first a part of the iron ore fines, a part of the carbonaceous material and at least a part of an MgO-containing auxiliary raw material among the auxiliary materials are premixed and pelletized to form a preliminarily pelletized material; then the outer circumference of the preliminarily pelletized material is coated with a part of a CaO-containing auxiliary material among the auxiliary materials to form a coated preliminarily pelletized material; successively the coated preliminarily pelletized material and the remaining portion of the blended raw materials are mixed and pelletized; and the resulting pellet is supplied to the sintering machine. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a method for producing sintered ore used as a raw material when melting hot metal in a blast furnace, and in particular, the drop strength despite the low content of SiO ₂ and CaO, which are components forming blast furnace slag. The present invention relates to a technique for producing sintered ore having a high (shutter strength) and good properties of reduced powdering RDI.

In recent years, high-quality lump iron ore tends to be depleted, and the utilization ratio of sintered ore is further increased as an iron source material to be charged into a blast furnace. This sintered ore consists of iron sources such as powdered iron ore, sulfated iron, iron sand, scales, blast furnace dust and converter dust, limestone as ironmaking material, and carbonaceous material as heat source for return or firing. The mixture is used as the material. Usually, after adding, mixing, and granulating a proper amount of moisture to the blended raw material, filling it in layers on a pallet, burning the carbonaceous material with air flowing downward, melting the blended raw material, and then cooling Manufactured by crushing. That is, the sintered ore is a so-called artificial ore in which an iron source such as powdered iron ore reacts with a fossil (slag) component such as CaO or SiO ₂ as a flux and is melted to be agglomerated. In the firing process of this sintered ore, the ore and auxiliary materials such as lime react with each other due to the heat generated by the combustion of coke, which is a coagulation material, and calcium ferrite (CaO · nFe ₂ O ₃ , CaO · nFe ₃ O ₄ ). And melts such as olivine (SiO ₂ · Fe ₂ O ₃ ) are generated.

However, since the sintered ore currently used in the blast furnace has a higher content of SiO ₂ and CaO than the massive iron ore, the ratio of the sintered ore in the iron source material charged into the blast furnace However, the amount of blast furnace slag generated increases and the fuel ratio of the blast furnace (the amount of fuel necessary to melt 1 ton of hot metal) and the cost of processing the generated blast furnace slag increase. It has occurred. Recently, from the viewpoint of resource saving and energy saving, there is an increasing demand for reduction of the fuel ratio and slag ratio (slag amount / blast furnace raw material amount) of the blast furnace.

On the other hand, reducing the content of SiO ₂ and CaO in the sintered ore causes a decrease in strength of the sintered ore and deterioration of reduced powdering property (RDI). A method for producing a 9 wt% low slag sintered ore (see Patent Document 1), a method for producing a sintered ore with an SiO ₂ average of 5 wt% or less and CaO / SiO ₂ of 1.90 to 2.10 (Patent Document 2) see), SiO ₂ is 4.2~4.9mass%, MgO is at 1.5~3.0mass%, method for producing sintered ore of CaO / SiO ₂ is 1.8 to 2.2 (Patent Document 3 And a method for producing sintered ore with SiO ₂ of 4.6% or less, CaO / SiO ₂ of 1.0 to 3.0, and MgO exceeding 0.5% (see Patent Document 4). are, but the way these conventional manufacturing are all due to the reduction of SiO _2, CaO content drop strength (Shi Potter strength:. Which hereinafter referred to as "SI") not solve the problem of a decrease is, at present, the lower limit of the SiO ₂ content of about 4.5Mass%, the lower limit of the CaO content is 9. It is suppressed to about 0 mass%, the drop strength (SI) is about 85%, and the reduced dustability (RDI) is about 40%. In addition, in the sintered ore containing 4.5 mass% or more of current SiO ₂ and 9.0 mass% or more of CaO, the drop strength (SI) is about 89%, and the reduced powdering property (RDI) is about 35%. .

Also, in contrast to the method of reducing so-called “flux” such as SiO ₂ and CaO to be contained, a method of increasing the carbonaceous material content in the blended raw material to maintain the current strength and reduced powdering property is also conceivable. In such a case, the microstructure of the sintered ore becomes a large number of crystals derived from the olivine-based melt produced at the time of melting, which causes another problem that the reducibility (RI) of the sintered ore is deteriorated.

As a method of reducing the so-called "flux", in addition to the above, after forming the lower pre-granulated product of SiO ₂ content, performing granulation again by adding high SiO ₂ content material, blast furnace slag There has been proposed a method for producing a sintered ore that can maintain a drop strength (SI) of 90% or more even if the content of the component to be formed is less than the conventional one (see Patent Document 5).
Japanese Patent Laid-Open No. 10-273738 Japanese Patent Laid-Open No. 11-80845 JP-A-11-131151 JP 2000-178659 A JP 2005-220399 A

  However, in the method described in Patent Document 5, it is necessary to increase the amount of carbonaceous material added to the preliminary granulated material in order to strengthen the bond between the preliminary granulated material and the remaining raw materials. There is a problem that the amount increases. As the amount of carbon material used increases, the reducibility (RI) of the sintered ore deteriorates as described above.

  This invention is made | formed in view of this situation, Even if there is less content of the component which forms a blast furnace slag than 90%, the fall strength (SI) of 90% or more and the reduction | restoration powdering property of 35% or less ( It is an object of the present invention to provide a method for producing sintered ore that can maintain (RDI) and prevent deterioration of reducibility (RI).

  The inventors diligently studied the above-mentioned problems of the prior art during research aimed at realizing the above object, and realized the results in the present invention.

That is, the present invention mixes a blended raw material composed of fine iron ore and other iron source raw materials, auxiliary raw materials, and carbonaceous material, and after adding water and granulating the mixture, the carbonaceous material is supplied to the sintering machine. by burning melted, _{cooled, SiO 2: 4.0~5.0mass%, CaO} : in the production of sintered ore containing 7～9Mass%, first, the iron source material containing at least fine iron ore A part, a part of the carbonaceous material, and at least a part of the auxiliary raw material containing MgO among the auxiliary raw materials are premixed and granulated to form a preliminary granulated product, on the outer periphery of the preliminary granulated product A coated preliminary granulated material is formed by coating a part of the auxiliary raw material containing CaO among the auxiliary raw materials, and then the coated preliminary granulated material and the remainder of the blended raw material are mixed and granulated. It is a manufacturing method of a sintered ore characterized by supplying to a sintering machine.

In this case, it is desirable to form a pre-granulated product using fine iron ore having a SiO ₂ content of 3.6 mass% or less during the above-described pre-granulation. Furthermore, at the time of the coating preliminary granulation, the preliminary granulated product may be coated with an auxiliary raw material containing CaO to form a coated preliminary granulated product having a CaO content of 1 mass% or more and 9 mass% or less. Furthermore, in the preliminary granulation, in addition to the auxiliary raw material containing fine iron ore and charcoal and MgO, the auxiliary raw material containing CaO is added, and the granulation of CaO content of 4 mass% or less (excluding 0 mass%) is performed. An object may be formed. Moreover, in these present invention, it is preferable that the carbonaceous material content of the said granulated material shall be 1 mass% or more.

The auxiliary raw material that is the raw material of the sintered ore contains CaO, SiO ₂ , Al ₂ O ₃ , MgO, etc., but mainly contains CaO, and the content of MgO is less than 10 mass%. An auxiliary material containing CaO, mainly containing MgO, and an MgO-containing auxiliary material containing 10 mass% or more of MgO. As an auxiliary material containing MgO, dolomite, magnesite, brucite, serpentine, Ni slag, or the like can be used.

  According to the present invention, after pre-granulating a part of the compounding raw material for sintering and further coating with the auxiliary material containing CaO, re-granulation together with the remaining compounding material is performed, and then sintering is performed. A sintered ore having a core having a high strength and mainly composed of a system melt can be produced. As a result, even if the content of the components forming the blast furnace slag is less than conventional, it has a drop strength (SI) of 90% or more and a reduced dusting property (RDI) of 35% or less, and the reducibility (RI). Can be produced. Thereby, the generation amount of blast furnace slag is reduced, and the fuel ratio of the blast furnace can be reduced.

  Hereinafter, the best embodiment of the present invention will be described based on the circumstances leading to the invention.

The sintered ore is obtained by reacting and melting an iron source such as fine iron ore with a so-called “flux”, that is, a slag component such as CaO or SiO ₂ , and cooling to agglomerate. Therefore, it is well known that various factors such as the particle size of the blended raw material and the blending ratio (basicity) affect the strength of the sintered ore. In particular, SiO ₂ content of 4.0～5.0Mass%, the low slag sinter of about 7～9Mass% CaO content, with a decrease of the flux components such as CaO and SiO _2, is melt volume Due to the shortage, the drop strength (SI) of the sintered ore as the product is significantly reduced. Further, when SiO ₂ content is below 4.5Mass% becomes remarkable even deterioration of reduction degradation properties (RDI).

Therefore, the present inventors have made various attempts to produce a melt that does not depend on the added flux component. As a result, a granulated product of fine iron ore having a SiO ₂ content of 3.6 mass% or less and a part of the carbonaceous material is obtained. It is formed in advance (referred to as a pre-granulated product formed by pre-granulation), and is covered with the remaining raw materials (raw materials not used for pre-granulation among the blended materials). When it was granulated again into a layer structure and then sintered, it was found that a sintered body having a relatively high reducibility and a high strength could be obtained, and based on this finding, the invention described in Patent Document 5 was completed. However, if the amount of carbonaceous material added (contained) in the pre-granulated material is less than 6 mass%, the amount of melt produced may be insufficient and the desired strength may not be obtained. It was preferable that the content be 6 mass% or more.

  Therefore, in order to make further improvements, a method for bonding the interface between the pre-granulated material and the remaining raw materials was examined. As a result, a coated pre-granulated product obtained by coating the auxiliary granulated material containing CaO on the pre-granulated product is formed (referred to as a coated pre-granulated product formed by the coated pre-granulated product), and the rest is left. When re-granulated so as to cover with a raw material (a raw material that was not used for the above pre-granulation and coating pre-granulation among the blended raw materials), and then sintered as a three-layer pseudo-particle, it was relatively reducible. It has been found that a sintered body with high strength and high strength can be obtained with a small amount of carbonaceous material. Further, the present invention was completed by finding that the auxiliary granule containing MgO is mixed in advance in the pre-granulated product so that the magnetite structure is stabilized and good reduction powderability can be obtained.

  Reduced pulverization of sinter is caused by expansion associated with the crystal structure change from hematite to magnetite during the reduction process. Furthermore, the main cause of reduced powdering is secondary hematite, which is generated by reoxidation when magnetite existing at a high temperature of 1300 ° C or higher where calcium ferrite decomposes and melts during the sintering reaction is cooled. Therefore, in order to reduce reduced powdering, it is effective to suppress the formation of secondary hematite, that is, to improve the residual ratio of magnetite. It is known that MgO reacts with iron oxide to promote the formation of magnetio ferrite having a magnetite structure in sintering, and in general, the formation of magnetite structure is good for reducing powdering properties. The reducibility deteriorates. This is because magnetite is generated from the melt, so the crystals are likely to be coarsened, and the amount of fine pores in the sintered structure is reduced. In the present invention, however, the amount of melt produced in the pre-granulated product should be reduced. Therefore, magnetite containing MgO can maintain reducibility. Therefore, even if the content of MgO in the pre-granulated product is small, the effect is exhibited. What is necessary is just to determine the upper limit of MgO content in a preliminary granulation as a case where all the auxiliary materials containing MgO are contained in a preliminary granulation.

In this coating pre-granulation, it is desirable to form a pre-granulated product using fine iron ore having a SiO ₂ content of 3.6 mass% or less. When fine iron ore having a SiO ₂ content of 3.6 mass% or less is used, the amount of olivine-based melt produced is reduced, and high reducibility is easily obtained.

  Further, in the present invention, in the preliminary coating granulation, the preliminary granulated product may be coated with an auxiliary material containing CaO to form a coated preliminary granulated product having a CaO content of 1 mass% or more and 9 mass% or less. desirable. This is because when the content is less than 1 mass%, the coating effect does not appear, and when it exceeds 9 mass%, the CaO content in the remaining raw material decreases, and the strength of the outer layer portion of the pseudo particles decreases.

Next, the present inventors examined a suitable range of the amount of carbonaceous material added to the pre-granulated product. In a pre-granulated product (pre-granulated product described in Patent Document 5) of fine iron ore and carbonaceous material having an SiO ₂ content of 3.6 mass% or less that does not cover CaO-containing auxiliary materials, Since the amount of liquid generation is insufficient and the desired strength cannot be obtained, the carbon material addition (content) amount is set to 6 mass% as the lower limit. However, in the present invention, the shortage of melt generation is used as a preliminary granulated product. A part of the auxiliary raw material containing CaO was coated, and a melt was formed by the coating containing CaO in the outer layer of the pre-granulated material to compensate for the lack of melt generation. The regulation of the amount of carbon material added (containing) in the pre-granulated product can be relaxed by the combination of this pre-granulated product and the coating auxiliary material containing CaO covering the pre-granulated material, and the addition of carbon material (containing) Even if the amount was less than 6 mass%, the production was possible. In the combination of the pre-granulated product and the coating auxiliary raw material containing CaO covering the pre-granulated material, the carbonaceous material addition amount of the pre-granulated material is as follows.

  That is, the carbonaceous material addition amount in the pre-granulated product can be 1 mass% as the lower limit in the present invention. If the amount of carbon material added (contained) is less than 1 mass%, the amount of melt produced in the pre-granulated product is too small, and the combination of the auxiliary granulated material containing CaO covering the pre-granulated material and the pre-granulated material is also possible. Since the strength is insufficient and the desired strength may not be obtained, the carbon material addition amount is preferably set to 1 mass% as the lower limit. In addition, the upper limit of the amount of carbon material added in the above is not particularly required, and may be determined according to the manufacturing economy. When higher strength is required, the amount of carbonaceous material added is desirably 6 mass% or more. However, since the reducibility of magnetite decreases as the amount of melt increases, it is desirable that the amount of carbon material added is determined by appropriately adjusting the upper limit of about 6 mass%.

  In the present invention, the strength is exhibited by the combination of the pre-granulated product and the coated auxiliary material containing CaO covering the pre-granulated material as described above, at the interface between the pre-granulated material and the coated auxiliary material. It is presumed that the increase in strength was exhibited as a result of the formation of calcium ferrite being held and the generation of calcium silicate having a low strength being suppressed.

That is, the tensile strength of calcium ferrite is 102 MPa, the tensile strength of calcium silicate is 19 MPa, and the SiO ₂ content when calcium ferrite is transformed into calcium silicate is low in the pre-granulated product (SiO ₂ containing An amount of 3.6 mass or less) also has an advantageous effect on strength retention, and it is presumed that the strength increase is exhibited as a whole.

  Next, an embodiment of a method for producing a sintered ore according to the present invention will be described with reference to FIG. FIG. 1 is a flowchart for explaining an example of a manufacturing process of sintered ore according to the present invention. In the following description, only powdered iron ore is used as an iron source material, and sintering is performed by the steps (A) to (I). This is the case of producing ore. Hereinafter, each process of (A)-(I) is demonstrated in detail.

(A) First, in producing a sintered ore having a SiO ₂ content of 4.0 to 5.0 mass%, a blend of fine iron ore that is an iron source (a blend of sintered raw materials) is determined. That is, based on the amount of powdered iron ore used for the production of the pre-granulated product, the amount of other powdered iron ore used is obtained, and the sintering with SiO ₂ content of 4.0 to 5.0 mass% as the total sintering compound raw material Define raw material composition. In addition, when using powdered iron ore with a SiO ₂ content of 3.60 mass% or less in the pre-granulated product, the amount of other fine iron ore used based on the amount of powdered iron ore with a SiO ₂ content of 3.60 mass% or less. Is determined as a total sintering blending raw material, and a sintering raw material blending having a SiO ₂ content of 4.0 to 5.0 mass% is determined. On the contrary, SiO ₂ content such that the content of SiO ₂ 4.0～5.0Mass% as gutted sintering mixed material of SiO ₂ content 3.60Mass% less other compounding other than fine iron ore You may obtain | require the usage-amount of fine iron ore of 3.60 mass% or less.

  (B, C) Subsequently, the MgO-containing auxiliary material and the amount of carbon material for the fine iron ore used for the preliminary granulated material are determined, and these are mixed. As the MgO-containing auxiliary material used here, dolomite, magnesite, brucite, serpentine or Ni slag can be used.

  (D) Moreover, CaO and the amount of carbonaceous materials are similarly determined about sintering raw materials other than the powdered iron ore used for the preliminary granulated material which is the remaining sintering raw materials.

  (E) The amount of the auxiliary raw material containing CaO coated on the preliminary granulated material is determined.

  (F) After determining and mixing the MgO-containing auxiliary raw material and the amount of carbonaceous material with respect to the fine iron ore used for the preliminary granulated product, water is added and granulated to obtain the preliminary granulated product. The pre-granulated material only needs to have a strength that does not collapse during mixing and granulation with the remaining other sintering raw materials, and water or quick lime, bentonite, molasses, etc. may be used as a binder. That's fine A bread pelletizer can be used as the granulator.

  (G) A drum mixer can be typically used for coating the preliminary granulated material and the coating material. Coating material is added to the pre-granulated material, charged from the entrance side of the drum mixer, mixed and granulated by rolling, and the powdered coating material is packaged on the surface of the pre-granulated material. Granules are formed.

(H) Next, a drum mixer can also be used for mixing and granulating the coated pre-granulated product produced in (G) and the remaining sintered raw materials. CaO and carbonaceous material, the SiO ₂ raw material needed in addition, charged from inlet side of the drum mixer with coated pre-granulated product, water was added, mixed and granulated manipulate added covering preliminary granulation by rolling A powdery raw material is packaged on the surface of the product to make pseudo particles, and pseudo particles having a three-layer structure are manufactured.

  (I) The pseudo particles produced in (H) are placed on a sintering machine pallet and sintered by a sintering machine.

  In the following, the method for producing a sintered ore according to the present invention will be described in a specific example, and a sintered ore of a comparative example using a conventional production method will be described to confirm the effect of the present invention. In addition, when manufacturing these sintered ores, 9 brand iron ore shown in Table 1 was used, and it mix | blended with the ore compounding ratio shown in Table 1. These sintered raw materials are referred to as new raw materials. As the auxiliary material, limestone, dolomite, magnesite, brucite, Ni slag, and quartzite having chemical components shown in Table 2 were used. The mixing ratio of the new raw material and the auxiliary raw material was two kinds shown in Tables 3 and 4.

(Invention Example 1)
In this example, sintered ore was produced at a blending ratio shown in Table 3. In adjusting the blending raw material, silica stone is adjusted so that the SiO ₂ content in the sintered ore is 4.0 mass%, and limestone is adjusted so that the CaO content in the sintered ore is 7.0 mass%. Blended. In addition, the sintered ore of less than 5 mm that does not become a product is returned to the raw material as a return ore, but the return ore is blended so as to be 20 mass% with respect to the sum of the new raw material (fine iron ore raw material) and the auxiliary raw material.

  And in manufacture of a sintered ore, it carried out as follows (a)-(c).

  (A) First, to ores A, B, D, and G, dolomite was added and mixed so that the content of MaO content would be 1 mass% so that the content of carbonaceous material (powder coke) would be 1 mass%. Thereafter, preliminary granulation was performed with a pan pelletizer while adding water to obtain a preliminary granulated product. Therefore, among the ore brands in Table 1, those other than the ores A, B, D, and G are the remaining sintered raw materials that are not pre-granulated. The remaining sintering raw material shall include return ore.

  (B) Next, the auxiliary granule containing CaO is coated on the pre-granulated product so that the CaO content becomes 1 mass%, and limestone is used as a covering material together with the pre-granulated product obtained in (a). The mixture was put into a drum mixer, mixed and granulated while adding water, and a powdered coating material was externally coated on the surface of the pregranulated material to obtain a coated pregranulated material.

  (C) Next, the remainder of the blended raw material consisting of the remaining sintered raw material, the remaining auxiliary raw material, and the remaining carbonaceous material, together with the coated pre-granulated product obtained in (b), is a drum mixer. The mixture was mixed and granulated while adding water to obtain pseudo particles having a three-layer structure as a granulated product.

  The pre-granulated product obtained in the above (a) was 63 mass% in the iron ore raw material, and the remaining iron ore raw material was 37 mass%. The total amount of coal blended was 4.5 mass% with respect to the total amount of new raw materials and auxiliary raw materials. These manufacturing conditions are organized and shown in the column of Invention Example 1 in Table 5.

  The pseudo particles produced in the above (c) were charged into a sintering machine and sintered under normal air suction. The quality of the obtained sintered ore is shown in the column of Invention Example 1 in Table 6. Evaluation of the quality of sintered ore is based on the drop strength (shutter index: shutter strength indicated by SI) according to the method defined in Japanese Industrial Standard JIS M8711, and the reducibility index (method) defined in Japanese Industrial Standard JIS M8713. RI), and a reduced powder index (RDI) was determined by the method specified in Japanese Industrial Standard JIS M8720.

The sintered ore obtained in Inventive Example 1 has a high strength of SiO ₂ content of 4.0 mass%, CaO content of 7.0 mass%, SI of 90, RI of 66, and RDI of 33. It was a sintered ore with good reducibility and resistance to reduction dusting.

(Invention Example 2)
In this example, sintered ore was produced at a blending ratio shown in Table 4. Magnesite and brucite were previously added and mixed so that the content of MaO was 1 mass% so that the carbonaceous material content would be 1 mass% with respect to the ore brands A, B, D, and G fine iron ores. A sintered ore was produced in the same manner as in Example 1 except that the subsequent preliminary granulation was performed. Manufacturing conditions and quality are shown in Tables 5 and 6 in the column of Example 2 of the present invention.

The obtained sintered ore has a SiO ₂ content of 4.0 mass%, a CaO content of 7.0 mass%, SI of 90, RI of 66, and RDI of 34, high strength, reducibility, resistance It was a sintered ore with good reduced powdering properties.

(Invention Example 3)
Sintered ore was produced in the same manner as in Example 1 except that dolomite was added and mixed so that the MaO content was 4.0 mass% when the preliminary granulated product was produced. The production conditions and quality are shown in the column of Invention Example 3 in Tables 5 and 6.

The obtained sintered ore has a SiO ₂ content of 4.0 mass%, a CaO content of 7.0%, SI of 91, RI of 67 and RDI of 33, high strength, reducibility, resistance It was a sintered ore with good reduced powdering properties.

(Invention Example 4)
Sintered ore was produced in the same manner as in Example 1 except that the pre-granulated material was pre-granulated so that the carbonaceous material content in the pre-granulated material was 3 mass%, and a coated pre-granulated material was obtained. The production conditions and quality are shown in the column of Invention Example 4 in Tables 5 and 6.

The obtained sintered ore has a SiO ₂ content of 4.0 mass%, a CaO content of 7.0 mass%, SI of 91, RI of 67, and RDI of 32, high strength, reducibility, resistance It was a sintered ore with good reduced powdering properties.

(Invention Example 5)
Example 1 except that silica stone is mixed so that the SiO ₂ content of the product sintered ore is 5.0 mass%, and limestone is mixed so that the CaO content of the product sintered ore is 9.0% mass. A sintered ore was produced in the same manner. Production conditions and quality are shown in Tables 5 and 6 in the column of Example 5 of the present invention.

The obtained sintered ore has a SiO ₂ content of 5.0 mass%, a CaO content of 9.0 mass%, SI of 94, RI of 66, and RDI of 31, high strength, reducibility, resistance It was a sintered ore with good reduced powdering properties.

(Comparative Example 1)
Ore brands A to I all of the fine iron ores are made of silica so that the SiO ₂ content of the product sintered ore becomes 4.0% mass, and the CaO content of the product sintered ore becomes 7.0% mass. Limestone was formulated as follows. In addition, the return ore was blended so as to be 20 mass% with respect to the sum of the new raw material (fine iron ore raw material) and the auxiliary raw material.

  All the raw materials were put into a drum mixer and mixed and granulated while adding water to obtain single layer pseudo particles. The total amount of coal blended was 4.5 mass% with respect to the total amount of new raw materials and auxiliary raw materials. These manufacturing conditions are organized and shown in the column of Comparative Example 1 in Table 7.

  The quality of the sintered ore obtained after the above pseudo particles are charged into a sintering machine and sintered is shown in the column of Comparative Example 1 in Table 8.

The sintered ore obtained in Comparative Example 1 has a SiO ₂ content of 4.0 mass%, a CaO content of 7.0 mass%, an SI of 85, an RI of 73, and an RDI of 45, resulting in low drop strength. RI and RDI were inferior.

(Comparative Example 2)
Pre-granulation after adding and mixing only the carbonaceous material so that the content of the carbonaceous material is 1 mass% with respect to the ore brand A, B, D, G powder iron ore in advance, the CaO content is 10.0 mass% As described above, sintered ore was produced in the same manner as in Example 1 of the present invention except that limestone was externally coated on the surface of the preliminary granulated material to obtain a coated preliminary granulated material. Manufacturing conditions and quality are shown in the column of Comparative Example 2 in Tables 7 and 8.

The obtained sintered ore has a SiO ₂ content of 4.0 mass%, a CaO content of 7.0%, SI of 79, RI of 74, RDI of 46, low drop strength, RI, RDI Was inferior.

(Comparative Example 3)
Comparative Example 1 except that silica stone was mixed so that the SiO ₂ content of the product sintered ore was 5.0 mass%, and limestone was blended so that the CaO content of the product sintered ore was 9.0% mass. Produced in the same manner. Manufacturing conditions and quality are shown in the column of Comparative Example 3 in Tables 7 and 8.

The obtained sintered ore has a SiO ₂ content of 5.0 mass%, a CaO content of 9.0 mass%, SI of 86, RI of 66, RDI of 40, low drop strength, RDI Was inferior.

It is a flowchart explaining one Embodiment of the manufacturing method of the sintered ore concerning this invention.

Claims (4)

Mix the blended raw material consisting of iron source raw material containing at least fine iron ore, auxiliary raw material, and carbonaceous material, add water and granulate, then supply to the sintering machine, burn the carbonaceous material When a sintered ore containing SiO ₂ : 4.0 to 5.0 mass% and CaO: 7 to 9 mass% is manufactured by melting and cooling, first, a part of the fine iron ore and one of the carbon materials Part and at least a part of the auxiliary raw material containing MgO among the auxiliary raw materials are premixed and granulated to form a preliminary granulated product, and CaO of the auxiliary raw material is added to the outer periphery of the preliminary granulated product. A coated pre-granulated material is formed by coating a part of the contained auxiliary material, and then the coated pre-granulated material and the remainder of the blended material are mixed and granulated before being supplied to the sintering machine. The manufacturing method of the sintered ore characterized by the above-mentioned. The method for producing a sintered ore according to claim 1, wherein the pre-granulated material is formed using fine iron ore having a SiO ₂ content of 3.6 mass% or less.   The method for producing a sintered ore according to claim 1 or 2, wherein a coated pre-granulated product having a CaO content of 1 mass% or more and 9 mass% or less is formed.   The method for producing a sintered ore according to any one of claims 1 to 3, wherein the carbonaceous material content of the pre-granulated product is 1 mass% or more.

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