KR20190006006A - Method of manufacturing sintered ores - Google Patents

Abstract

Provided is a method for producing a carbonaceous material-containing sintered ores having a high productivity and capable of improving reduction efficiency. A sintered raw material obtained by blending carbonaceous internal powders and inorganic particles having an outer layer made of a raw material containing CaO in the periphery of the carbonaceous core in a conventional granulated particle is charged into a pallet of a downward sucking and sintering machine to produce sintered ores As a method of producing a carbonaceous built-in sintered ore, the mixing ratio of the carbonaceous internal particles to the sintered raw material is within a range of 10 mass% or more and 30 mass% or less.

Description

Method of manufacturing sintered ores

TECHNICAL FIELD The present invention relates to a technique for producing sintered ores used in a blast furnace or the like as a raw material for a steelmaking process. More specifically, the present invention relates to a method for producing sintered ores including a carbonaceous material (hereinafter referred to as a carbonaceous particle) .

In the blast furnace method, iron-containing raw materials such as iron ores and sintered ores are mainly used as iron sources. The sintered ores are produced in the following order. An iron ore having a particle diameter of 10 mm or less and soda ash composed of a raw material such as SiO ₂ -containing raw material such as silica, serpentine and refined nickel slag, a CaO-containing raw material such as limestone and quicklime, and a sintered material composed of powder coke or anthracite An appropriate amount of water is added to the raw material and mixed and assembled using a drum mixer or the like to obtain pseudo-particles. The raw material for sinter which becomes the pseudo-particle is charged into the circulating moving pallet of the sintering machine. In the sintering machine, the carbonaceous material contained in the raw material for sinter is burned and sintered, and the raw material for sinter which becomes the pseudo-particle becomes a sintered cake. The sintered cake is crushed, cooled, and sieved, and the sintered cake is recovered as a product sintered ores having a predetermined particle size or more. The sintered ores are a kind of compacted light produced in this way.

Recently, attention has been focused on a carbonaceous intrusive light in which iron sources such as iron ore and dust, and carbon materials such as coke are arranged close to each other as the compacted light. This is because the reduction efficiency can be improved and the temperature of the upper part of the blast furnace can be lowered by disposing the iron source such as iron ore and the carbonaceous material in close proximity in one compact light.

As such intense light, Patent Document 1 discloses a raw material containing iron-containing powders generated in a steelmaking process such as blast furnace, converter dust, rolling scale, sludge, and iron ore powder, a raw material such as coal or coke, And then mixing and kneading the mixture and supplying the starch solution to the pelletizer by a pelletizer. However, in the pellet for a raw material for a steel raw material disclosed in Patent Document 1, carbonaceous materials in the pellets disappear at the time of producing the sintered ore, and therefore iron-containing raw materials such as iron ore and carbonaceous materials are not actually arranged close to each other. In addition, simply reducing the particle size of iron ore or carbonaceous material for the purpose of close-spacing causes the movement resistance of the gas propagating heat to be excessively large, resulting in a lowering of the reaction rate and lowering of the reduction efficiency.

Technologies for the purpose of closely positioning iron ores and carbon materials are also disclosed in Patent Documents 2 to 5. The techniques disclosed in these documents are those obtained by mixing iron-containing raw materials such as iron ore and carbonaceous materials such as coke, compacting them by hot forming, or using them as raw materials for steel making in blast furnace, However, these compacted materials are non-porous ones composed of a uniform mixture or a multi-layered granulated product, so that the strength is insufficient and the differentiation becomes vigorous. Therefore, if it is charged to a blast furnace or the like, dehydration and reduction and differentiation are caused, and the air permeability of the blast furnace is deteriorated.

As a technique for solving such a problem, a technology of a carbonaceous compacted light has been proposed. Patent Document 6 discloses a method in which a metal iron-containing iron oxide powder such as a steel dust or a mill scale is coated on the periphery of a carbonaceous core made of a dissolving coke to form an iron oxide shell having a low oxidation degree, At a temperature of less than 300 DEG C for 0.5 to 5 hours to form a hard thin layer of iron oxide having a high oxidation degree only on the surface of the iron oxide shell.

Patent Document 7 discloses an iron oxide-containing iron oxide powder or iron oxide powder and a carbonaceous material such as a steel dust or a mill scale which are mixed and assembled by using a pelletizer and then the outer surface of the granulated product is coated with a metal iron- Discloses a technique of obtaining compacted light containing a coke powder having a size of 3 mm or less in a dispersed state in an iron oxide powder or an iron ore powder. Patent Document 8 discloses a method for producing carbonaceous internal particles in which a carbonaceous material is coated with an iron ore powder and a CaO-containing raw material, mixing the carbonaceous raw material with the raw material for sintering, and then sintering the mixture in a downsizing sintering machine.

Japanese Patent Application Laid-Open No. 2001-348625 Japanese Patent Publication No. 3502008 Japanese Patent Publication No. 3502011 Japanese Patent Application Laid-Open No. 2005-344181 Japanese Patent Application Laid-Open No. 2002-241853 Japanese Laid-Open Patent Publication No. 2011-195943 Japanese Laid-Open Patent Publication No. 2011-225926 Japanese Patent Publication No. 5790966

 Sato, Yoshinaga Mayumi, Ichitate Minoru, Kawaguchi Takazo, Review of modeling of assembly and aeration phenomena of raw materials for sintering, Iron and Steel, 1982, Vol.68, No.15, 2174-2181

According to the techniques disclosed in Patent Documents 6 and 7, an iron-containing raw material and a carbonaceous material are disposed in close proximity to each other with a suitable size and sufficient strength as a raw material for a steel making it easy to cause a reduction reaction, . However, in order to carry out these techniques, there is a problem that a facility for performing oxidation treatment by heating at a temperature of 200 ° C or more and less than 300 ° C in the air for 0.5 to 5 hours is required, and the production amount is limited.

In the technique disclosed in Patent Document 8, although limitation of the production amount is solved by producing the sintered body containing the carbonaceous material by the sintering machine, no consideration is given to the blending ratio of the carbonaceous inner particle to the sintering raw material. When the blending ratio of the carbonaceous internal particles to the raw material for sinter is too high, the productivity is lowered due to the strength reduction of the carbonaceous built-in sintered ores. When the blending ratio of the inorganic particles to the sintering raw material is too low, There is a possibility that you will not be able to enjoy it.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for manufacturing a carbonaceous material-containing sintered ores having a high productivity and capable of improving reduction efficiency.

The features of the present invention for solving such problems are as follows.

(1) A sintered raw material obtained by blending carbonaceous internal powders and internal particles formed of an iron oxide powder and an outer layer made of a raw material containing CaO in a conventional granulated particle around a carbonaceous core is charged into a pallet of a downward- Wherein the compounding ratio of the carbonaceous internal particles to the raw material for sinter is within a range of 10 mass% to 30 mass% inclusive.

(2) The method for producing a carbon-containing sintered ore according to (1), wherein a blending ratio of the carbon-containing particles to the sintering raw material is within a range of 15 mass% or more and 25 mass% or less.

By carrying out the method for producing a carbon-containing sintered ore according to the present invention, it is possible to improve the air permeability of the charging layer formed by the sintering raw material containing the carbon-containing particles. Since the charging layer having improved air permeability can be sintered in a short period of time as described above, by carrying out the method for producing a carbon-containing sintered ore in accordance with the present invention, it is possible to produce a carbon-containing sintered ores that can improve the reduction efficiency with high productivity.

Fig. 1 is a schematic view for explaining an example of a method for manufacturing a carbon-containing built-in sintered orbital according to the present embodiment.
Fig. 2 is a graph showing the relationship between the incorporation ratio of the carbonaceous internal particles and the charging density and air permeability.
Fig. 3 is a graph showing the relationship between the particle incorporation rate of the carbonaceous particles, the cold strength and the reduction potential.
Fig. 4 is a graph showing the relationship between the blending ratio of the carbon-containing particles having the particle packing ratio of 97 mass%, 90 mass%, and 80 mass%, and the sintering light production rate.

Hereinafter, the present invention will be described with reference to the embodiments of the invention, but the following embodiments do not limit the invention related to the claims. Fig. 1 is a schematic view for explaining an example of a method for manufacturing a carbon-containing built-in sintered orbital according to the present embodiment. A manufacturing method of the carbon-interior-contained particles and the carbon-containing sintered ores is described with reference to Fig.

First, as shown in Fig. 1, raw materials containing iron ore powders and calcium oxide (CaO) are uniformly mixed using a kneader to prepare a mixture. The mixture and the coke particles having particle diameters of 3 mm or more serving as the carbonaceous core are supplied to the granulator, and a predetermined amount of water is added. In the pelletizing machine, an outer layer composed of iron powder ore and mixed powder in which the quicklime is homogenized is formed around the coke particles by the crosslinking force of water, and the carbonaceous internal particles having a particle size of 5 mm or more are assembled. In such an assembling process, the carbonaceous internal particles are assembled, but not all of the assembled carbonaceous internal particles are embedded with the carbonaceous nucleus, and some granular particles containing no carbonaceous nucleus are contained. In the present embodiment, the term "abrasive particles" refers to abrasive particles which are assembled in the above-mentioned assembling step and contain abrasive grains containing abrasive core and abrasive grains which do not contain some abrasive grains. The particle diameter in the present embodiment is a particle size separated by using a sieve of a nominal mesh conforming to JIS (Japanese Industrial Standard) Z 8801-1. For example, the particle diameter of 3 mm or more refers to JIS Z 8801 -1 means a particle size separating into sieves using a sieve of 3 mm nominal mesh.

Subsequently, the conventional raw material is mixed with pseudo-particles which are ordinary assembled particles which are agitated and assembled with a drum mixer or the like, and carbonaceous internal particles are blended to obtain sintered raw materials. At this time, the carbon-interior particles are mixed so that the blending ratio with respect to the sintering raw material is in the range of 10 mass% to 30 mass%. In the present embodiment, the compounding ratio of the carbonaceous internal particles to the raw material for sinter is a value calculated by dividing the mass of the internal particle of carbonaceous material by the mass of the raw material for sintering.

The sintered raw material containing the carbonaceous internal particles is brought into the surge hopper of the down suction sorter. The raw material for sinter is charged from the surge hopper into the endlessly movable pallet to form a loading layer. In the present embodiment, the particles of the carbonaceous material are blended so that the blending ratio with respect to the sintering raw material is in the range of 10% by mass or more and 30% by mass or less. With such a blending ratio, the air permeability of the charging layer charged into the pallet can be improved. In order to further enhance the air permeability of the charging layer, it is preferable to set the blending ratio of the carbonaceous internal particles to the sintering raw material within the range of 10 mass% or more and less than 30 mass%, and the blending ratio should be within the range of 15 mass% to 25 mass% , And it is more preferable that the compounding ratio is 20 mass%.

The charging layer is ignited by an ignition furnace installed above and the charging layer is successively burnt by sucking gas upward from a windbox installed downward. The charging layer is sintered by the heat of combustion generated by the combustion to become a sintered cake. The thus-obtained sintered cake is crushed and set in the light-shading portion, and the compacted material having a size of about 5 mm or more is recovered as the carbon-containing built-in sintered ores. In this manner, a carbonaceous raw material-containing sintered ore is produced, and the carbonaceous material-containing sintered ore is used as a raw material for a blast furnace.

As described above, by incorporating the carbon-containing particles in the blend ratio of 10 mass% or more and 30 mass% or less, the air-permeability of the loading layer charged into the pallet is improved. Since the charging layer having improved air permeability is sintered in a shorter time than the charging layer having no improved air permeability, the productivity of the raw material-containing sintered ores can be improved by blending the particles with the carbonaceous material so as to be within the range of the above-described blending ratio. In addition, the manufacturing method of the carbonaceous built-in sintered ores according to the present embodiment can be carried out using an existing sintering machine, so that the facility cost for preparing a new sintering facility does not occur.

Also, in the process of assembling the carbonaceous internal particles, if the blending ratio of the coke particles to be the carbonaceous core with respect to the total mass of the carbonaceous internal particles is in the range of 1% by mass or more and 10% by mass or less, The same conventional agglomerating machine can be used as it is.

Next, the carbon-containing sintered ores will be described. In the carbonaceous built-in sintered ore produced by the method for producing a carbonaceous built-in sintered ore according to the present embodiment, iron sources such as carbonaceous material and iron ore are closely arranged in the compacted light. When the carbon material and the iron source are arranged close to each other in the compacted light, CO generated by the gasification reaction (endothermic reaction) on the carbon material side is used for the reduction reaction (exothermic reaction) on the iron source side and CO ₂ generated by the reduction reaction is used for the gasification reaction As used, these reactions are repeated at a rapid rate in a chain-like manner within the intense light, thereby improving the reduction efficiency. In addition, if the carbon material and the iron source are closely arranged, the heat required for the gasification reaction is supplied by the reduction reaction of the iron source, so that the thermal efficiency is also improved, and the temperature on the upper part of the furnace can be lowered without reducing the reduction efficiency. As described above, by using the carbon-containing sintered ore as the raw material for the blast furnace, the reduction efficiency can be improved and the temperature at the upper part of the blast furnace can be lowered.

Example

A sintering experiment was carried out using a cylindrical sintering test apparatus (hereinafter referred to as a sintering pot) having an inner diameter of 300 mm and a height of 400 mm. The pseudoparticles were charged into a sintering pot to a thickness of 400 mm to form a charge layer. The upper surface of the pellet was heated for 60 seconds by using a burner made of propane as fuel, and was ignited at 700 mmAq from the bottom of the sintering pot To prepare a sintered cake.

In the sintering experiment, the temperature of the combustion exhaust gas discharged from the lower portion of the sintering pot was measured, and the time from the ignition to the point when the temperature reached the peak was regarded as the sintering time. After the completion of the sintering experiment, the sintered cake was dropped once from the height of 2 m, and the sintered ores remained on the sieve of 10 mm of mesh was defined as the sintered ores. The product yield was calculated by dividing the mass of the sintered ores having a property of 10 mm or more by the mass of the sintered cake. The production rate t (t) of the sintered ores produced per unit time (h) and the unit area (m 2) of the sintered light per unit time (h) is calculated from the sintering pot sectional area (m 2) / (h x m < 2 >)) was calculated.

The coke particles serving as the core particles of the carbonaceous internal particles were coke particles having a particle diameter of 2.8 mm or more and 4.75 mm or less sieved using a sieve according to JIS Z 8801-1. A disk pelletizer was assembled around the coke particles so that the thickness of the mixed powder layer in which the iron ore powders (150 μm or less) and the quicklime were mixed was 5 mm to obtain a carbonaceous internal particle having a packing ratio of 97% .

On the other hand, the conventional granulated particles are prepared by adding water to an additive such as common mineral ores and limestone or powder cokes having a particle diameter of 2.8 mm or less and mixing the mixture so that the average particle size of the arithmetic average is about 3 to 4 mm One raw material was used. The particle size of the arithmetic mean was calculated by measuring the weight of the granulated particles sieved into a plurality of granular ranges and weighted by using the representative granular sizes of the respective granular ranges.

The thus-prepared conventional granulated particles were mixed with the carbon-containing internal granules to prepare a sintered raw material. The sintering raw material in which the compounding ratio of the carbonaceous internal particles to the raw material for sinter was changed was adjusted, and the sintering experiment was conducted using the raw material for sintering. Table 1 shows the conditions of the sintering experiment.

In each condition, CaO and SiO ₂ contained in the carbonaceous internal particles and the pseudo particles charged into the sintering pot were adjusted to limestone or silica so that the basicity became constant. Other ingredients were adverse. The powder coke was blended into the pseudo-particles so as to be 5 mass% with respect to the mass sum of the particles of the carbonaceous internal material and the raw material of the sinter.

Fig. 2 is a graph showing the relationship between the incorporation ratio of the carbonaceous internal particles and the charging density and air permeability. In the graph shown in Fig. 2, the abscissa is the particle incorporation rate (mass%), the ordinate axis is the charging density (dry-t / m3) and the ordinate axis is the air permeability (J, ) to be. The loading density (dry-t / m 3) in FIG. 2 is a value obtained by dividing the mass (t) charged into the charging pot as moisture-removed sintered raw material by the inner volume (m 3) of the sintering pot. The J · P · U (-) is an index used for evaluating the air permeability and is an index calculated according to the method described in Non-Patent Document 1.

As shown in Fig. 2, with the increase of the mixing ratio of the carbon-containing particles, the charging density of the charging layer was increased. On the other hand, the J · P · U index indicating the air permeability of the charging layer was improved to about 20 mass% as the blend ratio of the carbon-interior particles increased, but when the blend ratio of the inorganic particles embedded therein was increased, Was changed to decrease. This is considered to be because the particle of the carbonaceous internal particle is larger than that of the conventional particle of the granule, so that the internal particle of the carbonaceous particle charged becomes the air passage, and the air permeability is improved up to the blending ratio of about 20 mass%. On the other hand, when the compounding ratio exceeds 20 mass%, the air permeability decreases. This is because the fused internal granular particles dispersed in the charge layer are not able to withstand the load in the layer and are partially collapsed due to the reduction of the molten conventional granular particles connecting the granular particles inside the granular material, And that the carbonaceous internal particles are melted by the combustion heat of the powder coke increased by the increase of the charging density. In addition, when the compounding ratio of the particles containing the carbonaceous material exceeds 30 mass%, the air permeability of the loading layer is remarkably lowered.

Fig. 3 is a graph showing the relationship between the particle incorporation rate of the carbonaceous particles, the cold strength and the reduction potential.

In the graph shown in Fig. 3, the abscissa indicates the mixing ratio (mass%) of the carbonaceous particles, the vertical axis indicates the cold strength of the sintered orbitally embedded material and the other vertical axis indicates the reductant RI %) to be. In addition, the cold strength in Fig. 3 was measured in accordance with JIS M 8712, and the reducibility was measured in accordance with JIS M 8713.

As shown in Fig. 3, the cold strength showing the strength of the carbonaceous built-in sintered compact was slightly lowered with the increase of the blend ratio of the carbonaceous internal particles. This is believed to be attributable to the improvement in air permeability, but within the range of the blend ratio of the carbonaceous internal particles in the present experiment, such a large decrease in cold strength was not observed. On the other hand, the reducing ability was increased with an increase in the blending ratio of the carbon-containing particles. From this, it was confirmed that by increasing the compounding ratio of the carbonaceous particles, the reducing ability of the carbonaceous material-containing sintered ores, which are iron sources, can be increased.

Fig. 4 is a graph showing the relationship between the blending ratio of the carbon-containing particles having the particle packing ratio of 97 mass%, 90 mass%, and 80 mass%, and the sintering light production rate. In the graph shown in Fig. 4, the axis of abscissas is the incorporation rate of particles (mass%) in the carbonaceous material, and the axis of ordinates is the production rate (t / (hxm2)) of the carbonaceous material-containing sintered ores. Also, the round plots are the result of the carbonaceous internal particles having a core particle percentage of 97% by mass, the triangle plots are the result of the carbonaceous internal particles having the internal core particle ratio of 90% by mass, and the square plots are the internal core particle ratio Shows the result of the carbonaceous internal particles having 90 mass%.

As shown in Fig. 4, irrespective of the incorporation rate of the carbonaceous core, the production rate of the carbonaceous built-in sintered ores was improved up to about 20 mass% as the blending ratio of the carbonaceous internal particles increased. On the other hand, if the compounding ratio of the carbonaceous particles exceeds 20 mass%, the production rate of the carbonaceous built-in sintered ores decreases. This tendency is the same as the permeability of the charging layer.

Regardless of the presence of carbonaceous nuclei, the carbonaceous internal particles are larger in particle size than conventional granular particles. Therefore, regardless of the presence or absence of the carbonaceous core, by incorporating the carbon-containing particles so as to be within the range of the above-described blending ratio, the charged carbon-containing particles become air passages and the air permeability of the charging layer is improved, It is believed that the productivity of the present invention can be improved. From these results, it was found that the production rate of the carbonaceous built-in sintered ore, that is, the productivity of the carbonaceous built-in sintered ores can be increased by setting the blend ratio of the carbonaceous internal particles to 10% by mass or more and 30% by mass or less irrespective of the incorporation rate of the carbonaceous core .

As shown in Fig. 4, the profile showing the production rate of the carbonaceous material-containing sintered ores is a convex profile with a peak around 20 mass% of the blend ratio of the carbonaceous internal particles. For this reason, in order to increase the productivity of the carbonaceous built-in sintered ores, it is preferable to set the blending ratio of the carbonaceous internal particles within the range of 10 mass% to less than 30 mass%, and to set the blending ratio within the range of 15 mass% to 25 mass% , And it is more preferable that the blending ratio is 20% by mass.

As described above, by carrying out the method for producing the carbon-containing built-in sintered ores according to the present embodiment using the sintering raw material in which the internal particles are mixed so that the blending ratio with respect to the sintering raw material is in the range of 10 mass% to 30 mass% It has been confirmed by sintering experiments that a sintered organdrite having a high reducing ability which can be improved can be produced with high productivity.

Claims (2)

A sintered raw material obtained by blending carbonaceous internal powders and inorganic particles having an outer layer made of a raw material containing CaO in the periphery of the carbonaceous core in a conventional granulated particle is charged into a pallet of a downward sucking and sintering machine to produce sintered ores A method for producing a carbonaceous built-
Wherein the compounding ratio of the carbon-interior particles to the sintering raw material is within a range of 10 mass% or more and 30 mass% or less. The method according to claim 1,
Wherein a blending ratio of the carbonaceous internal particles to the raw material for sinter is within a range of 15 mass% or more and 25 mass% or less.

Images