Method for manufacturing sintered ore

Abstract

To stably obtain a high yield.SOLUTION: A method for manufacturing a sintered ore includes: a granulation step of blending a sintered raw material containing a plurality of types of iron ores, an auxiliary raw material and a coagulation material, and performing granulation treatment in a granulating machine; a sintered raw material charging step of charging the sintered raw material discharged from the granulating machine into a sintering machine by the charging device; a sintering step of sintering the charged sintered raw material and manufacturing a sintered cake; and a classification step of sieving the sintered cake into a product sintered ore and return fines by a classifying device, and further includes: a product sintered ore analysis step of analyzing the component content of the product sintered ore; a return fine analysis step of analyzing the component content of the return fines; and a charging condition control step of changing the charging condition of the charging device in the sintered raw material charging step, on the basis of the component content of the product sintered ore and the component content of the return fines obtained in each of the product sintered ore analysis step and the return fine analysis step.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for producing sintered ore for a blast furnace.

Background Art

[0002] Currently, the main raw material for blast furnace ironmaking is sintered ore. Sintered ore (finished sintered ore) used as a blast furnace raw material is generally produced by sintering raw materials for sintered ore production (sintering raw materials) containing iron ore in a downward suction Dwight Lloyd (DL) type sintering machine, and then sizing to a predetermined particle size by crushing, screening, etc. The finished sintered ore is sampled every 4 to 7 hours, and the elemental composition is measured by fluorescent X-ray analysis or chemical analysis. Based on this measurement data, the sintered ore production process and blast furnace operation are managed.

[0003] In recent years, high-quality and homogeneous iron ore has tended to be depleted, and due to the deterioration of the iron ore used as a sintering raw material, components such as gangue are contained in large amounts. As a result, the components of the sintered ore vary even within the same lot. In order to improve the production efficiency of blast furnace operation, it is necessary to finely manage the blending ratio of the sintering raw materials in the sintered ore production process, the blending ratio of the blast furnace raw materials in the blast furnace operation, and the operation conditions (such as in-furnace temperature and pressure) according to the component variations of the sintered ore.

[0004] On the other hand, Patent Document 1 discloses a method for producing sintered ore, which includes a first measurement step of continuously measuring the concentration of at least one component among the iron-containing raw material, the sintering raw material, and the granulated sintering raw material, a sintering step of sintering the granulated sintering raw material in a sintering machine to obtain a sintered cake, a crushing step of crushing the sintered cake to obtain sintered ore, a cooling step of cooling the sintered ore, a screening step of screening the cooled sintered ore into finished sintered ore and return ore, and a second measurement step of continuously measuring the concentration of at least one component among the cooled sintered ore, the finished sintered ore, and the return ore, and an adjustment step of adjusting the sintering raw material using the component concentration measured in the first measurement step and the component concentration measured in the second measurement step.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2019-131847 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] In Patent Document 1, according to the above technology, even if the component concentration of the sintering raw material fluctuates during the production of sintered ore, the fluctuation can be grasped and the blending amount of the sintering raw material and the production conditions of the sintered ore can be adjusted quickly, or the blending amount of the sintering raw material and the production conditions of the sintered ore can be adjusted using the change amount of the component concentration. Therefore, it is described that the production of a finished sintered ore with a small fluctuation in component concentration can be realized. That is, the above technology aims at quickly adjusting and producing a finished sintered ore with a small fluctuation in component concentration by using the component concentration measured in the first measurement step and the component concentration measured in the second measurement step.

[0007] On the other hand, the present inventors focused on the relationship between the component content of the finished sintered ore and the component content of the returned ore, and the yield used as one of the operation management indicators, during the operation of sintered ore production. The present inventors aim to provide a method for producing sintered ore that enables an improvement in yield. [Means for Solving the Problems]

[0008] [1] A granulation step of blending sintering raw materials including multiple types of iron ores, auxiliary raw materials, and binders and performing granulation treatment with a granulator; a sintering raw material charging step of charging the sintering raw materials discharged from the granulator into a sintering machine by a charging device; a sintering step of sintering the charged sintering raw materials to produce a sintered cake; and a classification step of screening the sintered cake into finished sintered ore and return ore by a classification device. Further, a finished sintered ore analysis step of analyzing the component content of the finished sintered ore, a return ore analysis step of analyzing the component content of the return ore, and a charging condition control step of changing the charging conditions of the charging device in the sintering raw material charging step based on the component content of the finished sintered ore and the component content of the return ore obtained in the finished sintered ore analysis step and the return ore analysis step, respectively. A method for manufacturing sintered ore having these steps. [2] The method for manufacturing sintered ore according to [1], wherein in the finished sintered ore analysis step, the finished sintered ore being conveyed by a conveying means or / and the return ore being conveyed by a conveying means in the return ore analysis step are directly analyzed. [3] The method for manufacturing sintered ore according to [1], wherein the component content analyzed in the finished sintered ore analysis step and the return ore analysis step is the CaO content. [4] The method for manufacturing sintered ore according to [1], wherein the component content analyzed in the finished sintered ore analysis step and the return ore analysis step is the CaO content, and in the charging condition control step, the charging conditions are changed based on the difference (ΔCaO) between the CaO content of the return ore and the CaO content of the finished sintered ore. [5] The method for manufacturing sintered ore according to [1], wherein the charging in the sintering raw material charging step is performed using an inclined chute, and the change of the charging conditions in the charging condition control step is performed by changing the inclination angle of the inclined chute. [6] The method for manufacturing sintered ore according to any one of [2] to [5], wherein in the finished sintered ore analysis step and the return ore analysis step, the analysis of the component content of the finished sintered ore and the component content of the return ore is performed using laser-induced breakdown spectroscopy (LIBS).

Advantages of the Invention

[0009] According to the present invention, by changing the charging conditions in the sintering raw material charging process based on the component content of the finished sintered ore and the component content of the returned ore, a high yield can be stably obtained.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0011] The method for manufacturing a sintered ore of the present invention includes a granulation step of blending a sintering raw material containing a plurality of types of iron ores, auxiliary raw materials, and a binder and performing granulation treatment with a granulator, a sintering raw material charging step of charging the sintering raw material discharged from the granulator into a sintering machine by a charging device, a sintering step of sintering the charged sintering raw material to produce a sintered cake, and a classification step of screening the sintered cake into a finished sintered ore and a returned ore by a classification device. Further, it includes a finished sintered ore analysis step of analyzing the component content of the finished sintered ore, a returned ore analysis step of analyzing the component content of the returned ore, and a charging condition control step of changing the charging conditions of the charging device in the sintering raw material charging step based on the component content of the finished sintered ore and the component content of the returned ore obtained in the finished sintered ore analysis step and the returned ore analysis step, respectively.

[0012] The present invention will be described below with reference to the drawings. First, with reference to FIGS. 1 and 2, each step of sintered ore production will be described. FIG. 1 is a diagram showing an example of a sintered ore production process of the present invention. As shown in FIG. 1, the sintered ore production process includes a raw material blending step S0, a granulation step S1, a sintering raw material charging step S2, a sintering step S3, a cooling and pulverizing step S4, and a classification step S5. The raw materials and semi-finished products that have undergone each step are conveyed to the next step by a conveying device such as a belt conveyor. Further, FIG. 2 is a diagram showing an example of sintering equipment (equipment from raw material blending (raw material blending step S0) to discharge of sintered ore (sintering step S3)) used in the production of sintered ore of the present invention. As shown in FIG. 2, the sintering equipment 100 includes a raw material tank group 1, a granulator 2, and a sintering machine 3 having an inclined flat plate chute type charging device 20.

[0013] The raw material blending step S0 is a step of blending the raw materials (sintering raw materials) of the sintered ore. For the sintering raw materials, iron raw materials such as iron ores (powders) of multiple brands, iron-containing miscellaneous raw materials such as scale and steelmaking dust, SiO2-containing auxiliary raw materials such as silica, MgO-containing auxiliary raw materials such as peridotite, CaO-containing auxiliary raw materials such as limestone, return ore, and a coagulant (carbonaceous material) that serves as a fuel for sintering (coagulation) are appropriately used. Each sintering raw material is stored in each raw material tank (11 to 1 X ) provided in the raw material tank group 1. A predetermined amount is cut out onto the belt conveyor for each sintering raw material and blended at a predetermined ratio (blending ratio), and then sent to the granulation step S1.

[0014] The granulation step S1 is a step of performing granulation treatment (adjustment of particle size distribution) on the blended sintering raw materials (blended raw materials). The blended raw materials conveyed by the belt conveyor are put into the granulator 2. In the granulator 2, after a mixing treatment for a predetermined time, moisture is added (humidified), and further granulation treatment by mixing for a predetermined time is performed. The blended raw materials after the granulation treatment (hereinafter also referred to as blended raw material granulates) are sent to the sintering raw material charging step S2.

[0015] This granulation step S1 aims to ensure the air permeability of the raw material filling layer. Through the granulation process, a part of the compound raw material particles becomes pseudo-particles. Generally, as described in the "Steel Handbook, 3rd Edition, Volume II, Ironmaking and Steelmaking, P84 (Figure 2.4) [October 15, 1979]", for the fine powder raw material with a particle size of less than 0.25 mm, which is the main object of the granulation process, particles of 1.00 mm or more are used as core particles and adhere to their surroundings to form pseudo-particles. However, it is said that for particles with an intermediate particle size of 0.25 mm or more and less than 1.00 mm, granulation is difficult and it is difficult to become pseudo-particles.

[0016] The sintering raw material charging step S2 is a step of charging the compound raw material granulated product onto the pallet (not shown) of the sintering machine 3. For charging the compound raw material granulated product, a charging device equipped with a segregation mechanism is used. Usually, an inclined flat plate chute type charging device 20 shown in Figure 2 is used. By charging the compound raw material granulated product, a raw material filling layer 10 is formed on the pallet, and the pallet continuously moving in the pallet traveling direction 5 sends it to the sintering step S3.

[0017] This sintering raw material charging step S2 aims to adjust the distribution of the binder in the height direction of the raw material filling layer 10 by segregation charging. The inclined flat plate chute type charging device 20 includes a compound raw material surge hopper 21 for storing the compound raw material granulated product and an inclined flat plate chute 22 that is inclined downward in the direction opposite to the pallet traveling direction 5. By charging the compound raw material granulated product in the compound raw material surge hopper 21 onto the pallet moving in the pallet traveling direction 5 using the inclined flat plate chute 22, a slope 10x is formed on the upstream side of the raw material filling layer 10. Due to the rolling classification action of the compound raw material granulated product on this slope 10x, particle size segregation occurs in the layer thickness (layer height) direction of the raw material filling layer 10. Specifically, those with a small particle size are likely to be charged to the upper layer side of the raw material filling layer 10, and those with a large particle size are likely to be charged to the lower layer side of the raw material filling layer 10. The reason will be described later, but the binder with a small particle size can be unevenly distributed on the upper layer side.

[0018] The sintering step S3 is a step of firing the raw material filling layer 10 formed by the compound raw material granulated product to produce a sintered cake 11 (sinter cake). When the raw material packed bed 10 on the pallet moves to below the ignition furnace 4, the ignition furnace 4 ignites the sintering carbonaceous material (agglomerate) on the surface of the raw material packed bed 10, and sintering of the raw material packed bed 10 begins. In addition, a wind box (not shown) is provided below the pallet, and air is sucked from below the pallet. This downward suction 6 causes air to flow into the raw material packed bed 10 from the upper side, and oxygen is supplied into the raw material packed bed 10, which passes through to the lower side of the raw material packed bed 10. As a result, the burning part of the agglomerate forms a high-temperature combustion zone 10A, which progresses from the upper part to the lower part of the raw material packed bed 10, and the raw material packed bed 10 is successively sintered. The sintered cake 11 obtained by sintering is discharged from the discharge end of the sintering machine 3, and is roughly crushed by a crusher (primary crushing) to sintered ore with a particle size of less than 200 mm, and is sent to the cooling and crushing process S4.

[0019] Here, the reason why the condensation material is unevenly distributed on the upper layer side in the sintering material charging step S2 described above is as follows. In the raw material packed bed sintering step S3, the cooled air flows into the raw material packed bed 10 from the upper side by the downward suction 6, but after the combustion zone 10A is formed, the heat generated in the combustion zone 10A moving from the upper side to the lower side accumulates, so that the upper part of the raw material packed bed 10 is generally prone to heat shortage and the lower part is prone to heat excess. By unevenly distributing the condensation material, which is the fuel for sintering, on the upper side, the amount of heat is adjusted to the heat shortage in the upper part and the heat excess in the lower part. The particle size of the condensation material is generally in the range of 0.5 mm to 3 mm.

[0020] The cooling and crushing step S4 is a step in which the roughly crushed lump-shaped sintered ore is cooled and crushed. The lump sintered ore is cooled by a cooling device to a temperature at which it can be transported by a belt conveyor. The lump sintered ore is then crushed by a crusher (secondary crushing) and sent to the classification step S5 in a finer particle size state.

[0021] The classification step S5 is a step of grading the pulverized sintered ore for use in a blast furnace. The crushed sinter is sized by screening with a multi-stage sizing device. Through the sizing process, sinter of a size suitable for charging into the blast furnace (finished sinter) is selected. A size suitable for charging into the blast furnace is, for example, sinter with a particle diameter of 5 mm or more and less than 50 mm. Here, a particle diameter of 5 mm or more and less than 50 mm means a particle size that is retained on a 5 mm sieve and passes through a 50 mm sieve when screened. Note that sinter with a particle diameter of 50 mm or more is subjected to a crushing process so that the particle diameter becomes less than 50 mm, and then the sizing process is performed again.

[0022] Each sizing device is, for example, a rocking classifier having an inclined screen (mesh), and a rocking motion is applied by an eccentric drive mechanism. By changing the rotational speed of the motor that rotates this drive mechanism, the classification intensity can be adjusted. The finished sinter selected in the classification step S5 is placed on the blast furnace transfer line L1, and the other sinter is placed on the return ore transfer line L2.

[0023] The blast furnace transfer line L1 is a line for transferring the finished sinter to the blast furnace facility. The blast furnace transfer line L1 is equipped with a transfer device such as a conveyor. The finished sinter with a particle size of 5 mm or more and less than 50 mm is transferred to the blast furnace facility and used as a raw material for blast furnace ironmaking. Note that the finished sinter is charged into the blast furnace by a plurality of belt conveyors together with coke, limestone, serpentine, etc., which are reducing materials manufactured in separate processes.

[0024] The return ore transfer line L2 is a line for returning fine sinter unsuitable for blast furnace raw materials to the raw material blending step S0. The return ore transfer line L2 is equipped with a transfer device such as a conveyor, and transfers sinter with a particle diameter of less than 5 mm (hereinafter also referred to as -5 mm sinter), which has a smaller particle size than the finished sinter, into the above-mentioned raw material tank for storing return ore. A particle diameter of less than 5 mm means a particle size that passes through a 5 mm sieve when screened. The transferred -5 mm sinter is blended into the sinter raw material as return ore.

[0025] Return ore is generated from the parts with insufficient strength in the sinter cake. Since it is weak due to insufficient strength, it becomes powdery with a particle size of less than 5 mm due to crushing in the cooling and crushing process S4, and falls through the sieve when sieved with a 5-mm sieve in the classification process S5, becoming return ore. As a cause of insufficient strength, it is considered that the progress of the sintering reaction was not sufficient and the agglomeration of the blended raw materials (sintering raw materials) did not proceed.

[0026] As shown in FIG. 1, the present invention, in addition to the above-described processes (S0 to S5), includes a finished sintered ore analysis process S6 for analyzing the component content of the finished sintered ore, a return ore analysis process S7 for analyzing the component content of the return ore, and a charging condition control process S8 for changing the charging conditions of the charging device in the sintering raw material charging process S2 based on the component content of the finished sintered ore and the component content of the return ore obtained in the finished sintered ore analysis process S6 and the return ore analysis process S7, respectively.

[0027] The inventors had been implementing component management of the finished sintered ore, which is a blast furnace raw material, in the operation management of sintered ore production. However, this time, when paying attention to the components of the return ore, they discovered that there is a certain relationship between the specific component content of the return ore and the specific component content of the finished sintered ore. Based on this fact, the inventors conceived the present invention of changing the charging conditions of the sintering raw material charging process S2 based on the component content of the finished sintered ore conveyed on the blast furnace conveying line L1 and the component content of the return ore conveyed on the return ore conveying line L2, and confirmed through verification that a stable and high yield can be obtained.

[0028] Here, the yield in this specification refers to the finished product yield, which is the ratio of the mass of the finished sintered ore to the mass of the sinter cake (mass of the finished sintered ore + mass of the return ore) excluding the floor ore. Since the production of sintered ore aims at the production of the finished sintered ore as a blast furnace raw material, it is preferable that the yield is high, that is, the amount of return ore is small. Conventionally, the yield has been monitored by the increment information of the return ore storage amount (return ore generation rate information) in the raw material tank for return ore storage.

[0029] The above-mentioned certain relationship means, for example, that the CaO content of the returned ore is lower than that of the finished sintered ore. The sintering raw materials include CaO-containing auxiliary raw materials (such as limestone and quicklime). CaO in the CaO-containing auxiliary raw materials is a raw material for the melt. This CaO reacts with Fe2O3 in the iron ore to generate a calcium ferrite (CaO·Fe2O3)-based melt, and the agglomeration of the blended raw materials (sintering raw materials) proceeds due to this melt. Therefore, in the melt generation (sintering) reaction of the sintering raw materials, CaO affects the amount of melt generated, that is, the strength of the sintered ore to be fired, and is an important factor directly related to the yield. As a reason for the CaO content of the returned ore being lower than that of the finished sintered ore, it is considered that in the part of the sintered cake where there are no CaO-containing auxiliary raw material particles, the amount of melt generated is insufficient due to insufficient CaO, resulting in insufficient strength, and thus it is recovered as returned ore. In the charging of the blended raw materials in the sintering raw material charging step S2, it is difficult to uniformly distribute the CaO-containing auxiliary raw material particles in the raw material filling layer. In the places where there are no CaO-containing auxiliary raw material particles and where there are only fine CaO-containing auxiliary raw material particles, returned ore is likely to occur.

[0030] Here, the coagulant is a heat source that generates a melt around the iron ore in the raw material filling layer, and is another important factor directly related to the yield. Even when the amount of CaO is insufficient, the temperature can be increased by increasing the amount of the coagulant present, and the amount of melt generated can be increased. Here, as described above, the upper part of the raw material filling layer 10 is likely to have insufficient heat and is known to be a place where returned ore is likely to occur. Therefore, the inventors compared the CaO content of the finished sintered ore and the CaO content of the returned ore, and when the difference between the two is equal to or greater than a predetermined value, it is judged that the progress of the sintering reaction in the upper part of the raw material filling layer is excessively reduced, and the inventors came up with the idea of changing the charging conditions of the charging device in the sintering raw material charging step S2 to further strengthen the upper layer segregation of the coagulant. Hereinafter, the finished sintered ore analysis step S6, the returned ore analysis step S7, and the charging condition control step S8 will be specifically described.

[0031] The finished sintered ore analysis step S6 is a step of analyzing the component content of the finished sintered ore being transported on the blast furnace transfer line L1. Taking as the measurement target the finished sinter ore sampled from the blast furnace conveying line L1 or the finished sinter ore (on the belt conveyor (on-belt)) being conveyed on the blast furnace conveying line L1, analyze the component content of at least one component. For example, sample and analyze a predetermined amount of the finished sinter ore from the blast furnace conveying line L1 every 2 to 6 hours. The analysis of the sampled finished sinter ore may be performed by the calcium oxide quantification method (JIS M 8221), the fluorescent X-ray analysis method, or EPMA (electron probe microanalyzer). The analysis of the on-belt finished sinter ore will be described later. Note that the component content of the finished sinter ore is the average value when multiple finished sinter ores are the measurement targets.

[0032] The return ore analysis step S7 is a step of analyzing the component content of the return ore being conveyed on the return ore conveying line L2. Taking as the measurement target the return ore sampled from the return ore conveying line L2 or the return ore (on the belt conveyor (on-belt)) being conveyed on the return ore conveying line L2, analyze the component content of at least one component. For example, sample and analyze a predetermined amount of the return ore from the return ore conveying line L2 every 2 to 6 hours. The analysis of the sampled return ore may be performed by the calcium oxide quantification method (JIS M 8221), the fluorescent X-ray analysis method, or EPMA (electron probe microanalyzer). It is preferable that the analysis of the return ore is performed by the same analysis method as that of the finished sinter ore. The analysis of the on-belt return ore will be described later. Note that the component content of the return ore is the average value when multiple finished sinter ores are the measurement targets.

[0033] Based on the component content of the finished sinter ore and the component content of the return ore obtained in the finished sinter ore analysis step S6 and the return ore analysis step S7 respectively, the charging condition control step S8 changes the charging conditions of the charging device in the sintering raw material charging step S2 to adjust the segregation charging strength. The evaluation of the component content values of the finished sintered ore and the returned ore is performed based on, for example, the following formula (1) when the component to be measured is CaO. Δ[CaO] (mass%) is the value obtained by subtracting the CaO content of the returned ore from the CaO content of the finished sintered ore (Δ[CaO] = CaO content of the finished sintered ore - CaO content of the returned ore), and Δc is a constant (mass%) previously derived based on operating results, for example, a value of 1.1 mass% or more and 1.2 mass% or less. It is also preferable to obtain a correlation formula in advance based on the relationship between Δc and the finished product yield, and determine it using this correlation formula. Δ[CaO]>Δc ··· Formula (1)

[0034] When Δ[CaO] satisfies formula (1), change the charging conditions. For example, increase the segregation charging strength to enhance the upper-layer segregation of the binder. Specifically, if the segregation charging device in the sintering raw material charging process S2 is the above-described inclined flat plate chute type charging device 20, reduce the inclination angle (angle with the horizontal plane) of the inclined chute (inclined flat plate chute 22). The range of the chute angle varies depending on equipment specifications, etc. In this embodiment, it is changed within the range of 45° to 60°. The adjustment amount of the inclination angle is preferably 5° to 10°. For example, if the inclination angle is reduced by 5° and formula (1) is still satisfied after a predetermined time, it may be further reduced by 5°.

[0035] By enhancing the upper-layer segregation of the binder, sintered ore that had a low CaO content and was distributed as returned ore to the returned ore conveying line L2 before adjusting the segregation charging strength is distributed as finished sintered ore to the blast furnace conveying line L1 due to the increased combustion heat of the binder. As a result, the value of the CaO content of the finished sintered ore decreases, and the value of Δ(CaO) becomes smaller than the value of Δc. When the value of Δ(CaO) becomes smaller than the value of Δc and formula (1) is no longer satisfied, terminate the change of the charging conditions.

[0036] By having the above-described charging condition control process S8, the present invention can stably obtain a high yield. Next, the analysis of the finished sintered ore and the returned ore on the belt (hereinafter, the measurement object on the belt is also referred to as the on-belt sample) described above will be explained.

[0037] In the finished sinter ore analysis process S6, the sampling of the finished sinter ore from the blast furnace transfer line L1 and the sampling of the return ore from the return ore transfer line L2 in the return ore analysis process S7 are carried out by sampling samples from the finished sinter ore and return ore being conveyed at predetermined time intervals and analyzing the sampled samples. Since it takes time to obtain the component analysis results, it has been difficult to implement appropriate management. Homogeneous and high-quality ores tend to be depleted, and inferior raw materials are often used in the production of sinter ore. Therefore, by directly analyzing the on-belt samples, it is preferable to finely control the segregation charging strength according to the fluctuations in the quality (components and particle size distribution) of the raw materials.

[0038] (Analysis of on-belt samples) Component analyzers (not shown in the figure) are respectively installed in the blast furnace transfer line L1 and the return ore transfer line L2, and the finished sinter ore and return ore (on-belt samples) on the belt conveyor are directly analyzed (while in the conveying state) as the analysis targets of the respective component analyzers. The component analyzer is, for example, a laser analyzer, an infrared analyzer, a neutron analyzer, a microwave analyzer, etc. By continuously measuring the components of the on-belt samples and performing on-line analysis, it becomes possible to sequentially obtain the component content data of the on-belt samples. Here, continuous measurement means a form in which electromagnetic waves, neutrons, etc. are continuously irradiated onto the analysis object to continuously obtain measurement values. When the electromagnetic wave is a pulsed laser or the like, the time interval between pulses may be in the order of microseconds to seconds depending on the pulse repetition rate. Also, continuous measurement may be intermittently performed. There may be a finite-time pause period between consecutive continuous measurements. Such a pause period can be appropriately selected so that the desired control becomes possible. From another perspective, continuous measurement may also be a form of non-contact measurement without sampling (taking samples) the analysis object moving on a conveying means such as a belt conveyor or a pallet.

[0039] For example, when measuring and analyzing the component content of an on-belt sample using a LIBS (Laser Induced Breakdown Spectroscopy) analyzer, a pretreatment is performed to remove surface deposits and / or moisture on the on-belt sample by irradiating the on-belt sample with laser light. Then, laser light for analysis is irradiated onto at least a part of the site irradiated with the laser light in the pretreatment, and component analysis is performed by laser-induced breakdown spectroscopy analysis to obtain component content data of the on-belt sample. This pretreatment is a process of removing surface deposits and moisture of on-belt sample particles by so-called laser ablation.

[0040] The LIBS analyzer includes a pretreatment laser light source and an analysis laser light source arranged in order in the conveying direction, a spectroscope (for example, AvanSpec-ULS2048CL-EVO manufactured by Avantes) that detects what wavelengths of light and at what intensities the light emission caused by the analysis laser light contains, an arithmetic processing unit, a control device, and other configurations necessary for measurement and analysis. The arithmetic processing unit acquires measurement data (data regarding the emission intensity of each wavelength) regarding the light emission generated from the on-belt sample output from the spectroscope, and analyzes the component composition of the on-belt sample by LIBS based on such measurement data.

[0041] Here, fine sintered ore particles with a size on the micron order adhere to the surface of the on-belt sample that has undergone the classification step S5. These sintered ore particles, which are surface deposits, have a different component content from the on-belt sample particles that are in lumps. When analyzing the on-belt sample without performing pretreatment, the irradiation target of the laser light for analysis tends to be the sintered ore particles that are surface deposits, and since the mass ratio of the sintered ore particles that are surface deposits is extremely small compared to the on-belt sample particles that are in lumps, it is highly likely that the analysis data does not represent the component content of the on-belt sample particles that are in lumps.

[0042] In addition, sintered ore may contain moisture due to water spraying for dust countermeasures during storage or transportation, or due to rainfall. When a laser is irradiated onto a sample containing moisture, at least a part of the energy required for plasma generation, which is supplied from the irradiated laser light, is used for moisture evaporation or the like. Therefore, there is a concern that the light emission from the sample will be significantly attenuated. Although it may be possible to partially correct the influence of moisture by further applying techniques such as multivariate analysis, since the analysis accuracy also decreases as the light emission intensity decreases, there is a concern that the reliability of the analysis results will also decrease.

[0043] Therefore, the above-described pretreatment is performed before irradiating the laser light for analysis, and the laser light for analysis is irradiated onto at least a part of the site irradiated with the laser light in the pretreatment to perform the analysis. By adopting such a configuration, the laser light for analysis is irradiated onto the on-belt sample particles that are lumps, and even when the sample contains moisture, it is possible to suppress a decrease in the signal intensity of the light emission, and it becomes possible to accurately measure the component content of the on-belt sample.

[0044] In addition, after the pretreatment and before irradiating the laser light for analysis, the position of the analysis part where the laser light for analysis is irradiated (for example, the height from the conveyance surface of the conveyance equipment such as a belt conveyor) is measured by irradiating the laser light for position measurement, and based on the measured position information, it is also preferable to irradiate the analysis part with the laser light for analysis. It becomes possible to specify the analysis position of the on-belt sample to be analyzed, and it becomes possible to more reliably focus the laser light for analysis on the analysis part (surface) of the on-belt sample particles to be analyzed. As a result, it becomes possible to measure the component content of the on-belt sample with even higher accuracy.

Example

[0045] The tests related to the present invention described above will be explained below. The tests were conducted on actual machines, and a sintering facility 100 (see Figure 2) equipped with an inclined flat plate chute type charging device 20 was used for sintering. In addition, LIBS analyzers were installed in the blast furnace conveying line L1 and the return ore conveying line L2, and the finished sintered ore and the return ore being conveyed on the belt conveyor were measured and analyzed online directly by the LIBS analyzer respectively. For the analysis by the LIBS analyzer, a laser light source with a pulse energy of 40 mJ, a wavelength of 1064 nm, a repetition frequency of 100 Hz, and a pulse width of 7 ns was used. CaO content data was acquired every 10 minutes. That is, for one analysis, the CaO content data was acquired by averaging 6000 spectral data obtained in one minute, and this was repeated at 10-minute intervals.

[0046] Immediately based on the analysis results, the inclination angle of the inclined chute (inclined flat plate chute 22) of the inclined flat plate chute type charging device 20 provided in the sintering machine 3 was adjusted. In the example of the present invention, when Δ[CaO] (mass%) obtained by the following formula (2) exceeded 1.2 mass%, the angle of the sintering raw material charging chute was decreased. Δ[CaO]=[CaO]a - [CaO]b ··· Formula (2) [CaO]a: CaO content of the finished sintered ore (mass%) [CaO]b: CaO content of the return ore (mass%)

[0047] The angle adjustment of the raw material charging chute was performed as follows. In the comparative example, the angle of the raw material charging chute was not adjusted. In the example of the invention, the angle of the chute was decreased by 5°.

[0048] The test results are shown in Table 1. The return ore ratio (mass%) in Table 1 is calculated as return ore mass / (return ore mass + finished product mass) × 100 (%), and the value obtained by subtracting this return ore ratio from 100 is the yield (finished product yield). The return ore mass and the finished product mass are the integrated masses over 24 hours.

[0049]

Table 1

[0050] As shown in Table 1, in the inventive example, the return ore ratio is controlled to be low. This is because the accurate charging conditions were adjusted in response to the component fluctuations of the sintering raw materials that occurred in a short period of time.

[0051] As described above, the present invention has been described in detail with reference to the drawings. However, it is needless to say that the present invention is not limited to the above-described configuration and various modifications can be made without departing from the gist of the present invention.

Explanation of Reference Numerals

[0052] 1: Raw material tank group, 2: Granulator, 3: Sintering machine, 4: Ignition furnace, 5: Pallet traveling direction, 6: Downward suction, 10: Raw material filling layer, 10A: Combustion zone, 10x: Slope, 11: Sinter cake, 20: Inclined flat plate chute type charging device, 21: Blended raw material surge hopper, 22: Inclined flat plate chute, 100: Sintering facility, S0: Raw material blending process, S1: Granulation process, S2: Sintering raw material charging process, S3: Sintering process, S4: Cooling and pulverizing process, S5: Classification process, S6: Finished sinter ore analysis process S7: Return ore analysis process, S8: Charging condition control process, L1: Blast furnace conveying line, L2: Return ore conveying line

Claims

1. A granulation step of blending sintering raw materials including a plurality of types of iron ores, auxiliary raw materials, and binders and performing granulation treatment with a granulator; A sintering raw material charging step of charging the sintering raw materials discharged from the granulator into a sintering machine by a charging device; A sintering step of sintering the charged sintering raw materials to produce a sintered cake; A classification step of screening the sintered cake into finished sintered ore and return ore by a classification device, and having: Further, A finished sintered ore analysis step of analyzing the component content of the finished sintered ore; A return ore analysis step of analyzing the component content of the return ore; A charging condition control step of changing the charging conditions of the charging device in the sintering raw material charging step based on the component content of the finished sintered ore and the component content of the return ore obtained in the finished sintered ore analysis step and the return ore analysis step, respectively. A method for producing sintered ore having.

2. The method for producing sintered ore according to claim 1, wherein the finished sintered ore being conveyed by a conveying means in the finished sintered ore analysis step and / or the return ore being conveyed by a conveying means in the return ore analysis step are directly analyzed.

3. The method for producing sintered ore according to claim 1, wherein the component content analyzed in the finished sintered ore analysis step and the return ore analysis step is the CaO content.

4. The component content analyzed in the finished sintered ore analysis step and the return ore analysis step is the CaO content, In the charging condition control step, the charging conditions are changed based on the difference (ΔCaO) between the CaO content of the return ore and the CaO content of the finished sintered ore. The method for producing sintered ore according to claim 1.

5. Charging in the sintering raw material charging step is performed using an inclined chute, The change of the charging conditions in the charging condition control step is performed by changing the inclination angle of the inclined chute. The method for producing sintered ore according to claim 1.

6. The method for producing sintered ore according to any one of claims 2 to 5, wherein in the finished sintered ore analysis step and the return ore analysis step, the analysis of the component content of the finished sintered ore and the component content of the return ore is performed using laser-induced breakdown spectroscopy (LIBS).

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