JP6436317B2 - Carbonaceous material-containing granulated particles for producing sintered ore and method for producing sintered ore using the same - Google Patents

Description

  The present invention relates to a technique for producing sintered ore used as a steelmaking raw material in a blast furnace or the like, and specifically, carbonaceous material-containing granulated particles as a sintering raw material used for the production of sintered ore and the same. It is related with the manufacturing method of the used sintered ore.

In the blast furnace iron manufacturing method, iron-containing raw materials such as iron ore and sintered ore are mainly used as iron sources. Here, the sintered ore is composed of an iron ore having a particle size of 10 mm or less, a SiO ₂ -containing material made of silica, serpentine, refined nickel slag, or the like, or a CaO-containing material such as limestone or quicklime. Add a suitable amount of water to a granulated raw material consisting of raw material, solid fuel (carbonaceous material), which is a coagulant composed of powdered coke and anthracite, and mix and granulate using a drum mixer, etc. After making a certain sintering raw material, the sintering raw material is charged on a pallet that is circulated and moved by a sintering machine, and the carbon material contained in the pseudo particles is burned and sintered, and the resulting sintered cake Is a kind of agglomerated ore obtained by crushing, sizing and recovering a product having a certain particle size or more as a product.

  By the way, in recent years, as the agglomerates, those in which an iron source such as iron ore and dust and a carbonaceous material such as coke are arranged in proximity are attracting attention. The reason is, for example, when an iron source such as iron ore and a carbon material are arranged close together in one agglomerate, the reduction reaction (exothermic reaction) on the iron source side and the gasification reaction (endothermic reaction) on the carbon material side ) Is repeated at a high speed, so that the iron-making efficiency is improved and the temperature in the furnace such as a blast furnace can be lowered.

  As the agglomerate, for example, as disclosed in Patent Document 1, the raw materials containing iron-containing powder generated in the iron-making process such as blast furnace / converter dust, rolling scale, sludge, iron ore powder or the like, respectively, coal, Some of them are granulated by adding carbonaceous materials such as coke and starch, mixing and kneading, and further supplying a starch solution with a granulator. However, in the agglomerated mineral disclosed in Patent Document 1, the carbonaceous material in the pellets is burned down during the production of the sintered ore, and thus the iron-containing raw material such as iron ore and the carbonaceous material are actually arranged close to each other. It is not a thing. In addition, simply reducing the particle size of iron ore or carbon for the purpose of close placement increases the resistance of gas to propagate heat too much, leading to a decrease in reaction rate and reduced iron production efficiency. I will let you.

  Then, some techniques aiming at the proximity | contact arrangement | positioning of an iron ore and a carbon material are proposed (for example, refer patent documents 2-5). The technology disclosed in these documents basically consists of mixing raw materials containing iron ore and other iron-containing materials with carbonaceous materials such as coke and then agglomerating them by hot forming or agglomeration without firing. As it is, it is used as a raw material for iron making in a blast furnace or the like. However, these agglomerates are non-fired ones consisting of a uniform mixture or multi-layered granulated material, so that the strength is insufficient and the powdering is intense. Further, there is a problem in that the amount of use is limited because it leads to reduced powdering and hinders the air permeability of the blast furnace.

  In addition, as a technique for solving the problems of the techniques of Patent Documents 2 to 5, for example, Patent Document 6 includes forming a nucleus with a raw material containing 5 wt% or more of metallic iron and / or 5 wt% or more of carbon, An agglomeration for iron making in which at least one outer peripheral layer containing the nucleus is formed from a raw material containing 10 wt% or more of metal iron and 5 wt% or less of carbon and then fired and agglomerated in an oxidizing atmosphere at 300 to 1300 ° C. Mines have been proposed. However, the agglomeration disclosed in Patent Document 6 also requires the use of metallic iron as a raw material, and since there are quantitative restrictions on the raw material used, there are restrictions on the amount that can be produced as agglomeration for iron making. There is a problem.

  Thus, as a technique for overcoming the above-mentioned problems of the Patent Documents 1 to 6, a technique for carbonaceous material agglomerated mineral has been proposed. For example, in Patent Document 7, iron oxide containing low iron oxide dust or mill scale is coated around a carbon material core made of small coke and coated with iron oxide powder containing metal iron such as iron dust and mill scale. After the shell is formed, an oxidation treatment is performed by heating in the atmosphere at a temperature of 200 ° C. or higher and lower than 300 ° C. for 0.5 to 5 hours, so that only the surface of the iron oxide shell is made of iron oxide having a high degree of oxidation. A technique for obtaining a carbonaceous material agglomerated mineral by forming a hard thin layer is also disclosed in Patent Document 8, in which iron oxide powder such as iron-making dust or mill scale or iron ore powder and carbonaceous material are combined with a granulator. The mixture is then granulated, and then the outer surface of the granulated material is coated with iron oxide powder containing metallic iron to form a low oxidation iron oxide shell. Technology to obtain agglomerates containing coke powder with a size of 3 mm or less in a dispersed state has been developed. It is.

  Patent Document 9 discloses a method in which a wet pellet obtained by coating a carbonaceous material with iron ore powder and a CaO-containing raw material is prepared, mixed with a sintered raw material, and then fired in a lower suction type sintering machine. .

JP 2001-348625 A Japanese Patent No. 3502008 Japanese Patent No. 3502011 JP 2005-344181 A JP 2002-241853 A JP-A-10-183262 JP 2011-195943 A JP 2011-225926 A Japanese Patent No. 5790966

  According to the techniques disclosed in Patent Documents 7 and 8, the steel material has an appropriate size and sufficient strength, and the iron-containing material and the carbonaceous material are arranged close to each other, easily causing an iron-making reaction, and reduced at low temperature. Can be obtained. However, there is a problem in that there is a need for equipment for performing an oxidation treatment in which heating is performed at a temperature of 200 ° C. or more and less than 300 ° C. in the atmosphere for 0.5 to 5 hours, and production is limited.

  Moreover, in the technique disclosed in Patent Document 9 above, a carbonaceous material-containing pellet obtained by coating and granulating a mixed powder of iron ore powder and CaO-containing raw material powder around a coke core is combined with a conventional sintering raw material by a sintering machine. By firing, the production limit is solved, but by firing in an air atmosphere of 1300 ° C or higher in the sintering machine, part of the carbonaceous material in the carbonized material agglomerated ore is lost by combustion. There is a possibility.

  This invention is made | formed in view of the said problem which a prior art has, and the objective is to manufacture a sintered ore from the sintering raw material containing a carbonaceous material interior granulated particle using a sintering machine. By avoiding restrictions on the production amount of sintered ore and using raw materials containing a large amount of FeO as coating raw materials for carbonaceous material-containing granulated particles, oxygen is consumed by the oxidation reaction in the coating layer during firing. An object of the present invention is to provide a method for suppressing the combustion of carbonaceous materials.

  As a result of intensive studies on the problems of the above-described conventional technology, the inventors used a raw material containing FeO, such as magnetite concentrate, as a coating raw material for carbonaceous material-containing wet granulated particles. In addition, part of the oxygen diffusing into the carbonaceous material interior granulated particles is consumed by the oxidation reaction of the magnetite, and the oxygen concentration consumed for the combustion of the carbonaceous material is reduced accordingly, increasing the residual carbon ratio after firing As a result, the present invention was developed.

  That is, the present invention is a carbonaceous material-containing granulated particle for producing sintered ore having a carbonaceous material core and an outer layer in which the periphery of the carbonaceous material core is covered with a mixed powder composed of iron ore powder and CaO source powder. In addition, the content of FeO in the iron ore powder is 1.0 mass% or more.

In addition, in the carbonaceous material-containing granulated particles for sinter production according to the present invention configured as described above,
(1) FeO in the iron ore powder is a refined fine powder of 5.0 mass% or more, or a pulverized ore, or a powder generated in a steelworks such as dust,
(2) The CaO source powder is a CaO-containing raw material such as quicklime, limestone, and dolomite, and the CaO content in the mixed powder is 10 mass% or less.
Is considered to be a more preferable solution.

  Further, the present invention is to combine the carbonaceous material-containing granulated particles for the production of sintered ore with other granulated particles for sintering to mix both granulated particles, and then mix the mixed granulated particles. It is in the manufacturing method of the sintered ore characterized by obtaining sintered ore by charging with a sintering machine and sintering.

  According to the present invention, by using a raw material containing 1.0 mass% or more of FeO such as magnetite concentrate as a coating raw material for carbonaceous material-containing granulated particles, oxygen diffused into the carbonaceous material-containing granulated particles during firing. Part of this is consumed by the oxidation reaction of magnetite, and the oxygen concentration consumed for the combustion of the carbonaceous material is reduced accordingly, so that the residual carbon ratio after firing can be increased.

It is a figure for demonstrating an example of the equipment row | line | column which implements the manufacturing method of the sintered ore using the carbonaceous material interior granulated particle of this invention as a sintering raw material.

  FIG. 1 is a diagram for explaining an example of an equipment row for carrying out a method for producing a sintered ore using the carbonaceous material-containing granulated particles of the present invention as a sintering raw material. The manufacturing method of the sintered ore used by this invention according to FIG. 1 is demonstrated.

  In the example shown in FIG. 1, coke particles as core particles of 3 mm or more, concentrate fine powder (PF) of 150 μm or less, and quick lime as a flux are mixed in a pelletizer, granulated, and 8 mm or more. The size of the carbon material is granulated particles. The above raw materials are granulated by using coke particles having a large particle size as nuclei, so they may be added simultaneously. Further, the charging ratio between the coke particles and the PF is determined so that the thickness of the outer PF layer becomes 2 mm or more with respect to the coke particles as the core particles.

  Next, the carbonaceous material-containing granulated particles obtained as described above are combined with ordinary granulated particles for sintering (pseudo particles) obtained by stirring and granulating conventional raw materials with a drum mixer or the like. Then, both granulated particles are mixed and carried into a surge hopper of the sintering machine, and loaded from the surge hopper onto a pallet on which the sintering machine circulates. In addition, since the carbonaceous material-containing granulated particles have a larger particle size than ordinary granulated particles for sintering (pseudo particles), the middle layer is likely to have a higher temperature during sintering than the upper layer side due to segregation during charging. And since it is contained in a large amount on the lower layer side, the sintering reaction can sufficiently proceed.

  As described above, the carbonaceous material-containing granulated particles (agglomerated ore) of the present invention can be produced using an actual machine sintering machine, and therefore can be mass-produced at low cost.

  Production of the sintered ore of the present invention is carried out by the above-described equipment row, and the feature of the present invention is that, as a sintering raw material for the production of sintered ore, iron ore powder and CaO around the carbon material core and the carbon material core. A carbonaceous material-containing granulated particle for producing sintered ore having an outer layer coated with a mixed powder consisting of a source powder, wherein the content of FeO in the iron ore powder is 1.0 mass% or more It is in the point which uses the sintering raw material containing granulated particles.

  Regarding the production of carbonaceous material-incorporated granulated particles for the production of sintered ore of the present invention, it is conventionally known if the content of FeO in the iron ore powder constituting the coating layer can be 1.0 mass% or more. Such a manufacturing method can be used.

  In the carbon material-containing granulated particles, the coke that forms the core of the granulated material burns, and when most of it disappears, hollow fired pellets are formed and the center part is a void, so the strength after firing is reduced. There's a problem. However, it was found that when the residual carbon ratio was 80% or more, the residual coke functioned sufficiently as a nucleus in the granulated product, and the strength of the fired pellets could be maintained without the central portion becoming a void. Therefore, in the present invention, the lower limit of the blending ratio of the magnetite concentrate in the raw material powder forming the outer layer of the carbonaceous material-containing granulated particles is the residual carbon ratio even when firing at a general temperature and time in the sintering process. Is the minimum blending ratio at which 80% or more, that is, the FeO content is 1.0%.

As the iron ore fines, the content of F eO is equal to or more than 5.0 mass%, concentrate fines, pulverizng ore, or it is preferable that the steelworks occurrence powders such as dust. This is because, by using these raw materials containing 5.0 mass% or more of FeO, as can be seen from the results in Table 1 below, because the residual carbon ratio is remarkably improved.

  Further, the reason why the CaO-containing raw material is blended in the raw material powder covering the carbon material is to melt the iron ore particles at a lower temperature and promote the sintering. However, when the CaO content in the raw material powder exceeds 10 mass%, the coating layer is excessively melted during firing, and the shape as granulated particles cannot be maintained. As a result, the encased coke may be exposed, burned, and lost. In order to prevent this, the CaO content in the raw material powder is preferably 10% by mass or less.

  Examples according to the present invention and comparative examples are shown below.

  In this test, carbon material-containing granulated particles were fired using an electric furnace, and the proportion of carbon remaining after firing was measured. Table 1 below shows the test conditions and results.

  Raw material powders with different FeO contents which become the outer layer of carbonaceous material granulated particles by changing the blending ratio of hematite concentrate with 0.2 mass% FeO and magnetite concentrate with 29.5 mass% FeO It was created. The comparative example with FeO content of 0.2 mass% used only hematite concentrate, and Example 5 with FeO 29.5 mass% used only magnetite concentrate.

  A dish-type granulator (also referred to as a pan pelletizer) having a diameter of 600 mm was used for producing wet pellets to be subjected to the firing test. By putting coke with a diameter of 3 to 5 mm, raw material powder mixed with hematite concentrate, magnetite concentrate and quick lime (5 mass%) as a component-adjusted CaO source into the granulator, and granulating while sprinkling water Carbonaceous material-containing granulated particles having a diameter of 12 to 14 mm and a water content of 8 to 10 mass% were prepared.

  The produced carbonaceous material-containing granulated particles were put into an electric furnace heated to a furnace temperature of 1300 ° C. and fired for 3 minutes and 5 minutes. The granulated particles before and after firing were subjected to chemical quantitative analysis, and the residual carbon ratio was calculated from the ratio of the amount of carbon remaining after firing and the amount of carbon before firing. Table 1 shows the test results.

  In the comparative example in which the outer layer of the carbonaceous material-containing granulated particles was formed using only hematite concentrate and CaO-containing powder, the residual carbon ratio decreased to 72% after firing for 3 minutes. Furthermore, when it is calcination for 5 minutes, it falls to 55% of the same, and it turns out that about half of the carbon in the carbonaceous material-containing granulated particles has disappeared by combustion.

  On the other hand, by replacing part of the hematite concentrate with magnetite concentrate, part of the oxygen that diffuses into the granulated particles inside the carbonaceous material during firing is consumed by the oxidation reaction of the magnetite, and the combustion of the carbonaceous material Since the concentration of oxygen consumed in the process decreases, the residual carbon ratio after firing can be increased. In the case of Example 1, the residual carbon ratio was improved to 80% after 3 minutes of calcination and recovered to 65% even after calcination for 5 minutes.

  In a normal sintering process, the sintered raw material is exposed to a temperature of 1300 ° C. or higher for about 3 minutes. In addition, in the carbon material-containing granulated particles, coke that forms the core of the granulated material burns, and when most of it disappears, a hollow baked pellet is formed and the center part is a void, so the strength after calcination is reduced. There is a problem of doing. However, it was found that when the residual carbon ratio was 80% or more, the residual coke functioned sufficiently as a nucleus in the granulated product, and the strength of the fired pellets could be maintained without the central portion becoming a void. Therefore, the lower limit of the blending ratio of the magnetite concentrate in the raw material powder that forms the outer layer of the carbonaceous material-containing granulated particles is set to an amount such that the FeO content is 1.0%.

  If the blending amount of magnetite concentrate is further increased, the ratio of residual carbon after firing will increase, and when coke nuclei are coated only with magnetite concentrate and CaO raw material, 90% or more of carbon will not burn. Remained.

  According to the carbonaceous material-containing granulated particles for producing sintered ore of the present invention, by producing sintered ore using the sintering raw material containing the carbonized material-containing granulated particles according to the present invention, high productivity is achieved. High quality sintered ore can be obtained. Therefore, by using the sintered ore obtained as a blast furnace raw material, it becomes possible to perform blast furnace operation with high productivity.

Claims (4)

A carbonaceous material-incorporated granulated particle for producing sintered ore, comprising a carbonaceous material core and an outer layer in which the periphery of the carbonaceous material core is coated with a mixed powder composed of iron ore powder and CaO source powder. The FeO content of 5 . More 0Mass% der is, carbonaceous material interior granulated particles for sintering ore production, characterized in that to reduce the oxidation of the oxygen concentration that is consumed in the combustion of carbonaceous materials magnetite in the iron ore fines during firing . The iron ore powder, concentrate fines, pulverizng ore, Moshiku the carbonaceous material decorated granulated particles for sintering ore preparation according to claim 1, characterized in that the steelmaking plant generating powder. The CaO Minamotokona is carbonaceous material interior granulated particles for sintering ore preparation according to claim 1 or 2 CaO content before Symbol powder mixture is equal to or less than 10 mass%.   The carbonaceous material-containing granulated particles for sinter production according to any one of claims 1 to 3 are mixed with other granulated particles for sintering to mix both granulated particles, and then mixed. A method for producing a sintered ore, wherein the granulated particles are charged into a sintering machine and sintered to obtain a sintered ore.

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