JP4972761B2 - Method for producing sintered ore and pseudo particles for producing sintered ore - Google Patents

Description

  The present invention relates to a method for producing sintered ore and pseudo particles for producing sintered ore, and more particularly to a method for producing sintered ore containing metallic iron.

  Conventionally, sintered ore obtained by mixing and granulating iron ore, pulverized coal, and other auxiliary materials to produce pseudo particles and then sintering has been used as a blast furnace raw material. Iron ore powder, carbonaceous materials such as coke powder and anthracite, and CaO-containing raw materials such as limestone and dolomite (hereinafter referred to as CaO-containing auxiliary raw materials), steel mill recovered powder, sintered ore sieving powder, quick lime, etc. A suitable amount of water is mixed with the auxiliary material at a predetermined ratio, and after adjusting the humidity by adding an appropriate amount of water, the mixture is granulated with a drum mixer or a disk pelletizer to produce pseudo particles.

  In recent years, semi-reduced sintered ore has attracted attention because it can compensate for part of the reduction reaction that has been carried out in the blast furnace by the sintering reaction process, and can reduce the basic unit of reducing material by the total of sintering and blast furnace. .

For example, a raw material containing 5 to 20 mass% carbonaceous material is granulated to form an inner layer, a raw material containing 2 to 5 mass% carbonaceous material is formed in the outer layer, and the two-layer pseudo particles are used as a part of the sintered raw material. A method for producing reduced sintered ore (see Patent Document 1) and a method for producing partially reduced pellets (see Patent Document 2) including a coating layer containing 25 mass% or more of CaO on the raw pellet surface have been proposed. .
Japanese Patent No. 2704673 Japanese Patent No. 3678034

In the sintering process of sintered ore, heat is generated by the combustion of coke, which is a coagulation material, and ore and auxiliary materials such as lime react to react with calcium ferrite (CaO · nFe ₂ O ₃ , CaO · nFe ₃ O ₄ ) Melts such as olivine (SiO ₂ · Fe ₂ O ₃ ) are generated. In the conventional semi-reduction and partial reduction techniques as described above, the inner layer portion melts due to the high temperature caused by the combustion of the carbonaceous material in the pseudo particles, and the amount of melt generated excessively increases during the firing process. It was difficult to obtain metallic iron because the melt flows and melts and re-oxidizes.

  At this time, the flow of suction gas is hindered in the portion where the amount of melt generated is excessive, and since no air is supplied to the lower sintering material layer, coke does not burn and unfired pseudo particles remain. Therefore, it is difficult to achieve a high reduction rate and metal iron content, and at the same time, the yield of sintered ore is reduced.

  The present invention has been made in view of such circumstances, and suppresses the combustion of the carbonaceous material embedded in the pseudo-particles for the production of sintered ore, resulting from the excess or deficiency of the amount of melt generated in the sintering process. Manufacturing of sintered ore with high content of metallic iron, preventing re-oxidation of metallic iron, achieving high reduction rate The object is to provide a method and pseudo-particles for the production of sintered ore.

  In order to stabilize the firing reaction and prevent reoxidation and achieve a high reduction rate and metallic iron content in the production of sintered ore, the present inventors maintain the amount of melt generated and the shape of pseudo particles during firing. Focused on sex. Further, it has been found that increasing the density of pseudo particles containing a large amount of reducing carbonaceous material is effective in preventing combustion shortage and dispersion due to excessive melt generation in the sintering process and preventing reoxidation. The inventors have conceived the following present invention.

That is, the present invention is to produce a compact by mixing fine iron ore and carbonaceous material among the blended raw materials of sintered ore so that the carbonaceous material content of the green compact is 10 mass% or more, After mixing and granulating the molded body and the remainder of the blended raw material, it is a method for producing a sintered ore characterized in that it is supplied to a sintering machine and sintered, and the SiO ₂ content is 3.6 mass% or less To produce a compact using powdered iron ore, to produce a compact by mixing powdered iron ore, carbonaceous material and CaO-containing auxiliary materials, and to produce a compact by pressing with a briquette machine It is preferable to do.

  Furthermore, among the blended raw materials of sintered ore, pseudo-particles in which the rest of the blended raw material is sheathed on the surface of a molded body formed from a part of fine iron ore and carbonaceous material, the carbonaceous material of the molded body It is a pseudo particle for producing sintered ore characterized in that the content is 10 mass% or more, and among the blended raw materials of sintered ore, the compact is composed of fine iron ore, carbonaceous material and CaO-containing auxiliary raw material. It is preferably formed from a part.

  According to the present invention, the combustion of the reducing carbonaceous material in the pseudo-particles for the production of sintered ore is suppressed, and the shortage and dispersion due to the excessive and insufficient amount of melt generated in the sintering process are prevented. While maintaining the yield of the product, it is possible to prevent reoxidation and to produce a sintered ore having a high reduction rate and metal iron content.

  In general, as one method for reducing the fuel ratio of a blast furnace, there is a concept of using metallic iron as a raw material for charging a blast furnace. Therefore, if the metallic iron is contained in the sintered ore, it is considered that the same function and effect as described above, that is, effective in reducing the blast furnace fuel ratio. However, the actual condition is that ordinary sintered ore contains almost no metallic iron. The reason for this is that although the iron source in the blended raw material is temporarily reduced by the reducing atmosphere due to the action of the carbonaceous material, etc. to produce metallic iron, the generated melt is fluidized and the shape of the pseudo particles can be maintained. This is because reoxidation occurs in a high-temperature oxidizing atmosphere after completion of the sintering reaction.

  Therefore, in the present invention, among the sintered raw materials that are the blended raw materials of the sintered ore, a part of the fine iron ore and a part of the carbon material are mixed to form a carbon material content of 10 mass% or more. Forming the body into a pseudo-particle inner layer by pressure molding strengthens the pseudo-particle, prevents combustion of the reducing carbon material due to oxygen aeration, suppresses fluidization of the melt, and prevents reoxidation At the same time, the shape is stabilized and the firing is stabilized.

  Hereinafter, the best embodiment of the present invention will be described together with the background to the development of the present invention.

The sintered ore is obtained by reacting and melting powder iron ore with a flux (slag components such as CaO and SiO ₂ ) and then agglomerating by cooling. However, the semi-reduced sinter ore is added with coke as a reducing material and a coagulating material 2 to 5 times as compared with ordinary sinter, so if the carbon material added as a reducing material burns and generates heat, it will melt in the firing process. The amount of generation may increase excessively.

  Therefore, the inventors have tried various methods for suppressing combustion of the reducing carbon material incorporated as the inner layer when the multilayer pseudo particles are used as the raw material charged in the sintering machine. During the study, it became clear that combustion of the interior carbonaceous material was suppressed by reducing the air permeability in the pseudo particles. As a result, as a raw material charged with the sintering machine, a part of the blended raw iron ore was mixed in advance with the carbonaceous material, and then formed into a compact by molding and the remaining blended raw material. Pulverized particles were produced by granulation, and when a sintered ore was produced using this as a raw material charged with a sintering machine, a metal iron-containing sintered body was found and the present invention was completed.

  That is, when using a compacted compact that contains part of the powdered iron ore of the raw material and contains the carbonaceous material, the internal pressure of the compact is associated with the gasification of the carbonaceous material because the compact is dense. As a result, the reducing atmosphere is strengthened, and it acts to suppress the invasion of oxidizing gas to suppress the combustion of the carbonaceous material contained in the interior. Arise.

  Next, in order to obtain the sintered ore which has the predetermined effect mentioned above, inventors examined also the suitable range of the carbon material addition amount in the said molded object. As a result, when the amount of carbonaceous material added in the compact is less than 10 mass%, metallic iron may not be obtained, so 10 mass% was set as the lower limit. Note that the upper limit of the amount of carbon material added may be determined according to demands on manufacturing, economy, and the like, and it is not necessary to set an upper limit in particular, but it is preferably about 25 mass%, for example. More preferably, the amount of carbon material added in the molded body is 10 to 20 mass%.

Furthermore, when forming into a compact by calcining, using pulverized iron ore with a SiO ₂ content of 3.6 mass% or less and a carbon material addition amount in the compact of 10 mass% or more, The production amount of the liquid decreased, the microstructure derived from the wustite melt increased, and a sintered body having both high strength and high reducibility was obtained, and the residual metal iron was also observed. Therefore, it is more preferable to use powdered iron ore having a SiO ₂ content of 3.6 mass% or less while being formed into a compact by pressure forming.

Using fine iron ore SiO ₂ content is less 3.6Mass%, and the use of pressure molded shaped bodies with the addition of carbonaceous material, not accompanied the gasification of carbonaceous material because the molded body is a dense The internal pressure of the molded body rises and the reducing atmosphere is strengthened, and acts to suppress the invasion of oxidizing gas, thereby producing a reoxidation inhibiting effect. As a result, a large amount of metallic iron remains stably in the sintered ore (molded body portion), and both high strength and high reducibility characteristics are obtained, and a sintered iron containing metallic iron is obtained. .

  Moreover, in this invention, when shape | molding said molded object, in addition to a fine iron ore and a carbonaceous material, CaO containing auxiliary | assistant raw materials (for example, limestone, calcined lime) can also be added. It is effective to keep the CaO content of the molded body at a relatively low content of 8 mass% or less. The reason is that, if the CaO content of this molded body is 8 mass% or less, even if CaO is contained, no excessive melt is generated. Use as a molded body to be molded by pressurization can be carried out without adding a CaO-containing auxiliary material. The CaO content of the molded body is preferably 4 mass% or less.

  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.

(A) First, in producing a sintered ore having a predetermined chemical component, the raw material composition of fine iron ore, CaO-containing auxiliary material, and carbonaceous material is determined. The current blast furnace charging sintered ore has a SiO ₂ content of 4.6 to 5.2 mass% and a CaO content of about 8.8 to 12.0 mass%.

  (B, C) Subsequently, the amount of powdered iron ore to be used for molding is determined, the amount of CaO-containing auxiliary material and carbonaceous material for this is determined, and the CaO-containing auxiliary material and carbonaceous material are added to and mixed with the powdered iron ore. .

  (D) After mixing CaO-containing auxiliary materials and carbonaceous materials with fine iron ore, water is added and pressure-molded to form a compact. The molded body only needs to have strength that does not collapse during mixing and granulation with the remaining other sintering raw materials, and water, bentonite, molasses, or the like may be used as a binder. A briquetting machine can be used as the pressure molding machine.

(E) The powdered iron ore, the CaO-containing auxiliary material, and the carbonaceous material, which are the remaining sintered raw materials, not used for the production of the molded body, are mixed and granulated. A drum mixer can be used for mixing and granulating the formed body and the remaining sintered raw materials. The remaining fine iron ore, CaO-containing auxiliary raw material and the carbonaceous material, further if necessary the SiO ₂ raw material added, was charged with the molded body from the inlet side of the drum mixer, mixing and adding the granulation operation by rolling Thus, pseudo particles having a powdery raw material packaged on the surface of the molded body are produced.

  (F) The quasi-particles produced in (E) above are charged on the sintering machine pallet and sintered.

  Next, the pseudo particles for producing sinter according to the present invention will be described. The pseudo-particles for producing sintered ore of the present invention produced as described above are composed of an inner layer composed of a molded body containing fine iron ore and a carbonaceous material, and the remaining sintered raw material forming the molded body as an outer layer. Are two-layer pseudo-particles that are adhered and coated around the inner layer. An inner layer consists of a part of a sintered iron raw material ore and a carbonaceous material. The outer layer is the remainder of the sintered raw material that was not used in the production of the molded body, and consists of fine iron ore, carbonaceous material, CaO-containing auxiliary raw material, and other auxiliary raw materials. The molded body can also contain a part of the CaO-containing auxiliary raw material among the sintered raw materials.

  FIG. 2 is an explanatory view of pseudo particles for producing sintered ore according to the present invention, which has a molded body (inner layer) 1 containing at least fine iron ore and carbonaceous material as core particles, and the periphery remains. It consists of the adhesion part (outer layer) 2 of the sintering raw material. In the case of the pseudo particles produced in (E) above, the compact (inner layer) 1 is composed of fine iron ore, carbonaceous material, and CaO-containing auxiliary material, and the adhering part (outer layer) 2 is the remainder of the sintered raw material, Among sintered raw materials, it consists of fine iron ore, carbonaceous material, and CaO-containing auxiliary raw materials that were not used in the production of the compact.

  When the powdery raw material, which is the remainder of the sintered raw material, is packaged on the surface of the compact and the pseudo-particles for manufacturing the sintered ore, which is pseudo-particles, are sintered, metallic iron is added to the part that was the compact in the sintered ore. As a result, it is possible to obtain a sintered iron-containing sinter that remains in a stable state.

  While explaining the manufacturing method of the sintered ore of this invention based on this invention example 1-5, the effect of this invention is used using the comparative examples 1 and 2 which manufactured the sintered ore by the method outside the range of this invention. confirmed. In addition, when manufacturing these sintered ores, 9 brand iron ores having the composition shown in Table 1 were used as raw materials, and were blended in the ore blending ratio shown in Table 1. Table 2 shows the breakdown and chemical components of the auxiliary raw materials, and Table 3 shows the mixing ratios of the iron ore raw materials of ores A to I and the respective auxiliary raw materials.

(Invention Example 1)
In this example, in adjusting the blending raw material, Ni-slag was adjusted so that the SiO ₂ content in the sintered ore was 5.0 mass%, and the CaO content in the sintered ore was 9.4 mass%. Limestone was blended so that In addition, the sintered ore of less than 5mm, which is not a product, is returned to the raw material as return ore, but the return ore is blended so that it becomes 20 mass% with respect to the new raw material. Here, the new raw material is the sum of the iron ore raw material and the auxiliary raw material.

And in the production of sintered ore,
(A) First, after adding and mixing the ores A, B and F so that the carbonaceous material (powder coke) content is 10 mass%, water is added and pressure molding is performed with a briquette machine. Got the body. The molded body obtained by pressure molding with a briquette machine had an almond-like shape and was molded into a particle size having a volume of 10 cc. Therefore, among the ore brands in Table 1, those other than the above ores A, B, and F are the remaining raw materials for blending that are not pressure-molded. Here, the blended raw material is the sum of new raw material and return ore.
(B) Next, the remaining blended raw materials described above (C, D, E, H, I, auxiliary raw materials, return mineral, and the amounts of these can be determined in advance by blending calculation) are obtained in (a). The molded product was put into a drum mixer, mixed and granulated while adding water to obtain a granulated product (pseudo particles).

  The total amount of carbon in the blended mixture was 7.0 mass% with respect to the new raw material (5.8 mass% with respect to the total blended raw material). These manufacturing conditions are organized and shown in Table 4.

  Next, the granulated material produced as described above was placed on a pallet of a sintering machine and sintered under air suction according to normal operation. Table 5 shows the yield and metal iron content of the obtained sintered ore.

  The yield of sintered ore is obtained by dividing the mass of the product sintered ore by the mass of the sintered cake after firing, and expressing the value in terms of 100 minutes. The metallic iron content was determined by ordinary chemical analysis. As a result, the yield was as high as 82%, and a sintered ore containing 7.9 mass% of metallic iron stably was obtained.

(Invention Example 2)
Sintered ore was produced in the same manner as in Invention Example 1 except that the auxiliary material containing CaO was mixed when the formed body was produced. Add ore brand A, B, F fine iron ore, carbonaceous materials and auxiliary materials containing CaO to mix to obtain a compact, add limestone so that the amount of CaO in the compact is 8 mass% At the same time, blended so that the carbonaceous material content was 10 mass%, and after mixing these, water was added and pressure molded with a briquette machine to obtain a molded body. As a result, a sintered ore containing a high yield of 80% and containing 6.4 mass% of metallic iron stably was obtained. Production conditions and results are also shown in Tables 4 and 5.

(Invention Example 3)
Sintered ore was produced in the same manner as in Example 1 of the present invention, except that the carbonaceous material content relative to the ore was 12 mass% when the molded body was produced. Carbonaceous materials were blended to ores A, B and F so as to have a mass of 12 mass%, and after mixing these, moisture was added and pressure-molded with a briquette machine to obtain a compact. The total amount of coal blended was 8.0 mass% relative to the new raw material. As a result, the yield was as high as 85%, and a sintered ore containing 10.8 mass% of metallic iron stably was obtained. Production conditions and results are also shown in Tables 4 and 5.

(Invention Example 4)
A molded body is formed using ores C, D, and G, and materials other than ores C, D, and G are not subjected to pressure molding. The ore was produced. Carbonaceous materials were blended with respect to ore brands C, D, and G so as to have a mass of 10 mass%, and after mixing these, moisture was added and pressure-molded with a briquette machine to obtain a compact. As a result, the yield was as high as 83%, and a sintered ore containing 7.0 mass% of metallic iron stably was obtained. Production conditions and results are also shown in Tables 4 and 5.

(Invention Example 5)
Carbonaceous materials are blended to 10 mass% with respect to ore brands B, D, and G, and auxiliary materials containing CaO are mixed to form a compact, and other than ores B, D, and G are pressure molded. A sintered ore was produced in the same manner as in Example 1 except that the remaining raw material for blending was not used. Carbonaceous material is blended to 10 mass% with respect to ore brands B, D, and G, and after adding 4.0 mass% of the auxiliary material containing CaO, water is added and pressure molded with a briquette machine. Got. As a result, the yield was as high as 84%, and a sintered ore containing 10.3 mass% of metallic iron stably was obtained. Production conditions and results are also shown in Tables 4 and 5.

(Comparative Example 1)
All the raw materials of Invention Example 1 were put into a drum mixer and mixed and granulated while adding water. The total amount of charcoal blended was 7.0 mass% with respect to the new raw material. The granulated material was charged into a sintering machine, and the yield of sintered ore and the content of metallic iron obtained after sintering were determined in the same manner as in the present invention example. As a result, the obtained sintered ore had a low yield of 70% and contained almost no metallic iron.

(Comparative Example 2)
Carbonaceous materials were preliminarily blended with the iron ore brands A, B, and F so as to be 10 mass%, mixed, and then mixed with water and granulated. That is, the sintered ore was manufactured by the same method as Example 1 of this invention except having pressure-formed with the briquette machine. As a result, the obtained sinter had a low yield of 75% and contained almost no metallic iron.

It is a flowchart explaining the process example of the manufacturing method of the sintered ore which concerns on this invention. It is a figure explaining the pseudo | simulation particle | grains for sintered ore manufacture which concern on this invention.

Explanation of symbols

1 Molded body (inner layer)
2 Adhering part (outer layer)

Claims (2)

Among the blended raw materials of sintered ore, the powdered iron ore, the carbonaceous material and the CaO-containing auxiliary raw material containing dolomite are mixed and pressed with a briquette machine to produce an almond shaped molded body. Produced so that the carbonaceous material content is 10 mass% or more, mixed and granulated the molded body and the remainder of the blended raw material in a drum mixer , then supplied to the sintering machine and sintered A method for producing sintered ore. Method for producing sintered ore according to claim 1, characterized in that SiO ₂ content of producing shaped bodies using a fine iron ore is less than 3.6mass%.