Sinter manufacturing method

Abstract

To provide a method for manufacturing a sintering machine which can previously prevent occurrence of sump water and fluidization of a bulk material, and can prevent problems of operation stop caused by the sump water and the fluidization and facility failure.SOLUTION: A method for manufacturing a sintered ore, which adds moisture to a raw material for manufacturing a sintered ore containing fine ores, an auxiliary raw material, a solid fuel and a fine powder part of a product sintered ore, and mixes and granules the mixture, and thereby produces a granulated and sintered raw material that are pseudo particles, bakes the raw material by a Dwight Lloyd type sintering machine, and obtains a product sintered ore, measures component concentration and moisture content of the raw material for manufacturing the sintered ore, then charges a chemical into the raw material for manufacturing the sintered ore on the basis of the component concentration and the moisture content, and controls a flow state of the raw material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing sintered ore, in which water is added to a raw material for producing sintered ore, and the mixture is granulated to produce granulated sintered raw material, which is pseudo-particles, and the granulated raw material is fired in a Dwight Lloyd type sintering machine to obtain finished sintered ore. [Background technology]

[0002] So-called "bulk materials" such as iron ore, coal, and limestone used in steelmaking and other processes are transported by ships with deadweights of up to several hundred thousand tons, and are often stored in open air due to the large volume involved. Therefore, when heavy rain occurs, the moisture content rises significantly, causing the material to become fluid, making it difficult to adjust the transport and discharge speeds on conveyors and in intermediate storage tanks. In extreme cases, even when discharge devices such as vibrating feeders are stopped in intermediate storage tanks, a phenomenon known as "gushout" occurs, in which bulk materials flow out at high speed, leading to operational shutdowns.

[0003] For fluidization of bulk materials during transportation and storage, for example, Patent Document 1 proposes adding polymer flocculants and moisture adsorbents, and mixing bulk materials from other parts with the addition of polymer flocculants and moisture adsorbents. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-23374 Summary of the Invention [Problem to be solved by the invention]

[0005] The conventional technology described in Patent Document 1 adds polymer flocculants and moisture adsorbents when spring water or fluidization occurs. This is effective because the bucket can be stopped when moving bulk materials. However, a phenomenon known as "gushout" occurs in intermediate storage tanks, where bulk materials flow out at high speeds even when discharge devices such as vibratory feeders are stopped. This phenomenon presents a challenge: the discharge section of the intermediate storage tank becomes inoperable upon the occurrence of spring water or fluidization, resulting in unavoidable problems such as shutdowns for recovery and equipment damage. Alternatively, completely avoiding shutdowns and equipment damage due to spring water or fluidization requires the excessive addition of expensive polymer flocculants and moisture adsorbents. Furthermore, the method of mixing bulk materials from other locations proposed in Patent Document 1 also presents challenges in that it cannot be applied to situations where the stored materials are generally fluid, such as when rainfall lasts for a long period of time or when a large amount of easily fluidized fine powder is used.

[0006] An object of the present invention is to solve the above-mentioned problems and to propose a manufacturing method of a sintering machine that can prevent the occurrence of water seepage and fluidization of bulk materials in advance and prevent problems such as operation stoppage and equipment damage due to water seepage and fluidization. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems of the conventional technology and to achieve the above-mentioned object, we came up with a technology for controlling the fluidity state of raw materials for sinter production based on the component concentrations and moisture content of the raw materials for sinter production, and have developed the novel method for producing sinter described below.

[0008] That is, the present invention relates to a method for producing sintered ore, in which moisture is added to raw materials for producing sintered ore, including fine ore, auxiliary materials, solid fuel, and the fine part of finished sintered ore, and the mixture is granulated to produce granulated sintered raw materials, which are pseudo-particles, and the granulated sintered raw materials are fired in a Dwight Lloyd sintering machine to obtain finished sintered ore. The method is characterized in that the component concentrations and moisture content of the raw materials for producing sintered ore are measured, and then chemicals are added to the raw materials for producing sintered ore based on the component concentrations and moisture content to control the flow state of the raw materials.

[0009] In the method for producing sintered ore according to the present invention configured as described above, (1) measuring the Al2O3 component concentration of the raw material for sinter production and estimating the fluidization limit moisture content of the raw material for sinter production; (2) measuring the moisture content of the raw material for producing sintered ore and adding a chemical agent having aggregating or dispersing properties; and (3) measuring the Al2O3 component concentration of the raw material for sinter production, estimating the fluidization limit moisture content of the raw material for sinter production, measuring the moisture content of the raw material for sinter production, and adding an agent having aggregating or dispersing properties; This is considered to be a more preferable solution. [Effects of the Invention]

[0010] According to the method for producing sintered ore of the present invention, the component concentrations and moisture content of the raw materials for producing sintered ore are measured, and then chemicals are added to the raw materials for producing sintered ore based on the component concentrations and moisture content to control the fluidity of the raw materials, thereby making it possible to prevent the occurrence of springing or fluidization of bulk materials in advance and to prevent problems such as operation stoppages and equipment damage due to springing or fluidization. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing an outline of the manufacturing process of sintered ore, which is the main raw material in the blast furnace ironmaking process. DETAILED DESCRIPTION OF THE INVENTION

[0012] <Development process of the sintered ore manufacturing method according to the present invention> The inventors measured the moisture content of raw materials for sinter production, and if the moisture content exceeded a predetermined level, for example 13%, they switched to a different lot of raw materials for sinter production, or if high moisture content was predicted in advance, they mixed it with other raw materials with lower moisture content to prevent blowout due to fluidization. However, in the case of prolonged rainfall, it was not easy to secure raw materials with low moisture content, and the supply of raw materials was delayed due to draining and drying. Therefore, by using a chemical that suppresses fluidization when the moisture content exceeded 13%, it was possible to ensure a stable supply of raw materials even during prolonged rainfall.

[0013] In recent years, raw material brands have become more diverse, and the degree of fluidization can vary even with the same moisture content. Initially, we thought that the difference in fluidization was due to specific gravity and particle surface roughness, and addressed this by setting a moisture content threshold for each brand. However, with inexpensive brands, specific gravity and particle surface roughness can vary even within the same lot, so we had no choice but to use excessive amounts of chemicals.

[0014] The inventors believed that excessive chemical use was unavoidable when setting a moisture content threshold for each brand of raw material, and decided to estimate the fluidization limit moisture content from component concentrations (T.Fe, CaO, SiO2, MgO, Al2O3) regardless of brand. This made it possible to grasp changes in raw material properties by measuring component concentrations, even when the specific gravity and particle surface roughness fluctuated even within the same lot, particularly for inexpensive brands, and optimized the amount of chemicals used, which had been excessive.

[0015] When observing brands with a high fluidization limit moisture content, it was noticed that brands in which the gangue portion peeled off in thin flakes tended to have a high fluidization limit moisture content. When the flake-like peeled portions were analyzed by X-ray diffraction, a large amount of kaolinite was detected. Kaolinite is used alone as clay in porcelain materials, but it can also be contained in iron ore as gangue, and its content differs depending on the brand of iron ore, and the content can also vary even within the same brand.

[0016] Kaolinite has a structure consisting of alternating layers of Si-O tetrahedrons and Al-O octahedrons. It is believed that kaolinite exfoliates into flakes and retains water between the layers. This suggests that, compared to other gangue minerals such as quartz, kaolinite absorbs more water internally, reducing the amount of water exposed on the surface, thereby suppressing fluidization. Because of this structure, kaolinite is characterized by a higher Al2O3 ratio than other gangue minerals. The inventors therefore conceived the idea that the fluidization limit moisture content could be estimated using only Al2O3 among the component concentrations of the raw material, leading to the completion of this invention.

[0017] <Regarding the method for producing sintered ore according to the present invention> The present invention clarifies that, among the component concentrations of raw materials for sinter production, the Al2O3 concentration in particular has a large effect on the fluidization limit moisture content. Focusing on the Al2O3 concentration, the fluidization limit moisture content is estimated and measured, and a chemical is added to the raw materials for sinter production based on the estimated fluidization limit moisture content and the measured moisture content to control the fluidization state of the raw materials, thereby preventing the occurrence of spring water and fluidization in advance, even under conditions where the brand or particle size of the raw materials changes or where rainfall lasts for a long period of time.

[0018] Figure 1 shows an overview of the manufacturing process for sintered ore, the main raw material in blast furnace ironmaking. The raw materials used to manufacture sintered ore, so-called "bulk materials," including iron-containing raw materials such as iron ore and steelmaking dust, CaO-containing raw materials such as limestone and dolomite, and carbon-containing raw materials such as fine coke and anthracite, are often stored in open-air storage yards that are subject to rainfall. They are then transported by belt conveyor to an intermediate storage tank. A predetermined amount of raw materials for sintered ore production is then discharged from the intermediate storage tank, granulated in a granulator, and then loaded onto pallets in the sintering machine where they are sintered to become sintered ore. The route from the intermediate storage tank to the sintering machine is protected from rainfall by a roof or cover.

[0019] <Problems and Effects of the Sintered Ore Manufacturing Method According to the Present Invention> In the case of a phenomenon known as "gushout," in which bulk materials flow out at high speed even when discharge devices such as vibrating feeders are stopped in an interim storage tank, the discharge section of the interim storage tank becomes inoperable when spring water or fluidization occurs. This poses the problem of unavoidable problems such as shutdowns for recovery and damage to equipment. In response to this problem, the present invention measures the component concentrations and moisture content of the raw materials for sinter production, and then adds chemicals to the raw materials for sinter production based on the component concentrations and moisture content to control the flow state of the raw materials, thereby preventing the occurrence of water springing and fluidization in advance.

[0020] To completely avoid shutdowns and equipment damage due to spring water and fluidization, it was necessary to add excessive amounts of expensive polymer flocculants and moisture adsorbents as preventative measures. In response to this problem, the present invention estimates the fluidization limit moisture content from the component concentrations of the raw material for sinter production, measures the moisture content, and based on the estimated fluidization limit moisture content and the measured moisture content, adds a chemical to the raw material for sinter production to control the fluidity of the raw material, thereby preventing the occurrence of springing and fluidization in advance with the use of a necessary and sufficient amount of chemical.

[0021] Furthermore, the method of mixing loose materials from other parts proposed in Patent Document 1 also had the problem that it could not be applied in cases where the stored materials are generally fluid, such as when rainfall lasts for a long period of time or when a large amount of fine powder that is easily fluidized is used.

[0022] When measuring the moisture content of raw materials for sinter production and then using polymer flocculants or moisture adsorbents to prevent fluidization, the amount of moisture required for fluidization varies depending on the raw materials for sinter production, so it was unavoidable that fluidization would occur even when using polymer flocculants or moisture adsorbents, or that excessive polymer flocculants or moisture adsorbents would be used. In response to this problem, the present invention clarifies that, among the component concentrations of raw materials for sinter production, the Al2O3 concentration in particular has a large effect on the fluidization limit moisture content. The fluidization limit moisture content is estimated by focusing on the Al2O3 concentration, and the moisture content is measured. Based on the estimated fluidization limit moisture content and the measured moisture content, a chemical agent is added to the raw materials for sinter production to control the fluidization state of the raw materials, thereby preventing the occurrence of water seepage and fluidization in advance, even under conditions where the brand or particle size of the raw materials changes or where rainfall lasts for a long period of time. [Example]

[0023] <Comparative Example 1> The moisture content (mass%) of the raw materials for sinter production was measured. When the moisture content exceeded 13 mass%, the use of the raw materials for sinter production was stopped, and they were dried or mixed with other raw materials for sinter production with a lower moisture content. As a result, the sintering process was shut down four times per year.

[0024] <Comparative Example 2> The moisture content (mass%) of the raw materials for sinter production was measured. When the moisture content exceeded 13 mass%, a polymer flocculant was added in an amount of 1.6 mass% relative to the mass of water contained in the raw materials for sinter production. As a result, the sintering process was shut down twice a year.

[0025] Example 1 The component concentrations (t. Fe, CaO, SiO2, MgO, Al2O3) and flow values (an index of fluidity in accordance with JIS-R5201) at a moisture content of 13 mass% were measured in advance for various raw material samples for sinter production. The component concentrations (t. Fe, CaO, SiO2, MgO, Al2O3) and moisture content (mass%) of the raw material for sinter production were measured, and the flow value of the raw material sample for sinter production with the closest component concentration to the raw material for sinter production was selected. If the flow value was less than 14 cm, a polymer flocculant was added at 1.0 mass% relative to the mass of water contained in the raw material for sinter production. If the flow value was 14 cm or more but less than 16 cm, a polymer flocculant was added at 1.2 mass% relative to the mass of water contained in the raw material for sinter production. If the flow value was 16 cm or more, a polymer flocculant was added at 1.4 mass% relative to the mass of water contained in the raw material for sinter production. As a result, the sintering process was shut down once per year.

[0026] <Example 2> The Al2O3 content (mass%) and moisture content (mass%) of the raw materials for sinter production were measured. The amount of polymer flocculant added was calculated based on the mass of water contained in the raw materials for sinter production, as shown in the following formula. As a result, the sintering process had zero shutdowns per year, and the amount of polymer flocculant added was reduced to 0.4 mass% of the mass of water contained in the raw materials for sinter production. (formula) The amount of polymer flocculant added (mass%) relative to the mass of water contained in the raw materials for sinter production =0.8×(1-3×Al2O3 content ÷ moisture percentage) However, if the value of the expression is less than 0, it will be set to 0. [Industrial Applicability]

[0027] The present invention can prevent the occurrence of springing up and fluidization of bulk materials in advance, and can be suitably used for preventing problems such as operation stoppages and equipment damage caused by springing up and fluidization.

Claims

1. In a method for producing sintered ore, water is added to raw materials for producing sintered ore, including fine ore, auxiliary materials, solid fuel, and the fine part of the finished sintered ore, and the raw materials are mixed and granulated to produce granulated sintered raw materials, which are pseudo-particles, and the granulated raw materials are fired in a Dwight Lloyd type sintering machine to produce the finished sintered ore. As the raw material for producing sintered ore, The component concentrations and flow values (an index of fluidity in accordance with JIS R 5201) of various raw material samples for sinter production at a moisture content of 13% by mass were measured in advance. The component concentration and moisture content (mass%) of the raw material for sinter production to be used are measured, and the flow value of the raw material for sinter production sample having the closest component concentration to the raw material for sinter production is selected; A method for producing sintered ore, characterized in that when the flow value is less than 14 cm, a polymer flocculant is added in an amount of 1.0 mass% relative to the mass of water contained in the raw material for producing sintered ore, when the flow value is 14 cm or more but less than 16 cm, a polymer flocculant is added in an amount of 1.2 mass% relative to the mass of water contained in the raw material for producing sintered ore, and when the flow value is 16 cm or more, a polymer flocculant is added in an amount of 1.4 mass% relative to the mass of water contained in the raw material for producing sintered ore.

2. The method for producing sintered ore according to claim 1, wherein the component concentrations are Fe, CaO, SiO 2 , MgO, and Al 2 O 3 .

3. A method for producing sintered ore, comprising adding water to raw materials for producing sintered ore, including fine ore, auxiliary materials, solid fuel, and the fine powder portion of finished sintered ore, and mixing and granulating the raw materials to produce granulated sintered ore, which is pseudo-particle, and firing the granulated raw materials in a Dwight Lloyd sintering machine to obtain finished sintered ore, As the raw material for producing sintered ore, The Al 2 O 3 content (mass%) and moisture content (mass%) of the raw material for producing sintered ore are measured, A method for producing sintered ore, characterized in that a raw material for producing sintered ore is used to which a polymer flocculant is added in an amount represented by the following formula (1) relative to the mass of water contained in the raw material for producing sintered ore: Amount of polymer flocculant added relative to the mass of water contained in the raw material for producing sinter (mass %)=0.8×(1−3×Al 2 O 3 content / moisture content) (1) However, if the value of formula (1) is less than 0, it is set to 0.

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