Method for manufacturing sintered ore

Abstract

This invention provides a method for producing sintered ore by enriching the carbon material under more appropriate conditions when producing sintered ore using a sintering machine. [Solution] A method for producing sintered ore that enriches oxygen, characterized in that the oxygen supply rate, which is determined by formula (I) using the oxygen supply rate, which is the oxygen supply rate, which is the oxygen injection flow rate, and the amount of air intake in the oxygen enrichment region, which is the range in which oxygen injection is performed in the sintered layer, is multiplied by the oxygen utilization rate of the carbon material to be used as a binder, which has been determined in advance, is adjusted to produce sintered ore by adjusting at least one of the oxygen supply rate and the amount of air intake in the oxygen enrichment region, so that the oxygen consumption rate obtained is a desired value. A = Q + 0.21 × F (I). A is the oxygen supply rate, Q is the oxygen supply rate, and F is the amount of air intake in the oxygen enrichment region.

Description

[Technical Field]

[0001] This application relates to a method for manufacturing sintered ore. [Background technology]

[0002] In the operation of a sintering machine, it is known that enriching the air drawn into the sintering layer with oxygen increases the combustion rate of powdered coke and improves the production rate (see, for example, Patent Document 1). Patent Document 1 describes enriching the oxygen concentration in the combustion air drawn into the sintering layer to 35% or more during sintering. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 02-73924 [Overview of the project] [Problems that the invention aims to solve]

[0004] Sintered ore is produced by mixing iron ore with sintering raw materials such as sintering carbon (a binder) and allowing the sintering reaction to proceed in a sintering machine. Since the reactivity (combustibility) of the sintering raw materials (carbon) differs depending on the type of carbon, the optimal oxygen enrichment amount also differs for each type of carbon. Furthermore, even when using a mixture of multiple types of carbon, the optimal oxygen enrichment amount changes depending on the types and proportions of carbon used. However, this point has not been considered in prior art such as Patent Document 1.

[0005] The present invention aims to provide a method for producing sintered ore by enriching the carbon material under more appropriate conditions when producing sintered ore in a sintering machine. [Means for solving the problem]

[0006] This application was made to solve the above-mentioned problems, and its gist is as follows.

[0007] (1) A method for producing sintered ore that is oxygen-enriched, The oxygen supply rate, which is determined by the following equation (I), is calculated using the oxygen enrichment oxygen supply rate, which is the flow rate of oxygen injection, and the amount of air drawn into the oxygen enrichment region, which is the area in the sintered layer where oxygen injection takes place. The oxygen utilization rate of the carbon material to be used as a setting agent, A method for producing sintered ore, characterized by adjusting at least one of the enriched oxygen supply amount and the amount of atmospheric intake in the oxygen enrichment region so that the oxygen consumption rate obtained by multiplying by a value becomes a desired value, and supplying oxygen at an oxygen supply rate corresponding to the desired oxygen consumption rate to produce sintered ore. A = Q + 0.21 × F (I) Here, A[Nm 3 Q[Nm] is the oxygen supply rate, Q[Nm] 3 [ / min] is the oxygen enrichment supply, F[Nm³] 3 [ / min] represents the amount of atmospheric air intake in the oxygen-enriched region.

[0008] (2) The method for producing sintered ore according to (1), characterized in that the oxygen utilization rate is the slope of the approximate curve for the relationship between the oxygen consumption rate and the oxygen supply rate, which is obtained by performing sintering tests using the target carbon material while changing the oxygen supply rate to various values.

[0009] (3) The method for producing sintered ore according to (1) above, characterized in that the desired oxygen consumption rate is the oxygen consumption rate corresponding to the target sintering rate and the target yield in the first relationship, which is the relationship between the sintering rate and the oxygen consumption rate, and the second relationship, which is the relationship between the yield of the finished product and the oxygen consumption rate, which are determined by performing sintering tests using the target carbon material and varying the oxygen supply rate to various values.

[0010] (4) The method for producing sintered ore according to (1) above, characterized in that the amount of air drawn in the oxygen-enriched region is determined by multiplying the area of ​​the oxygen-enriched region by the oxygen-drawing wind velocity in the oxygen-enriched region.

[0011] (5) The method for producing sintered ore according to (1) above, wherein the amount of air suction in the oxygen-enriched region is determined by the following formula (II). F = (S / a) × (1 - ρ / 100) × V (II) Here, F [Nm 3 / min] is the amount of air suction in the oxygen-enriched region, S [m 2 is the area of the oxygen-enriched region, a [m 2 is the effective area of the sintering machine, ρ (volume %) is the air leakage rate in the sintering machine, and V [Nm 3 / min] is the air volume of the sintering machine.

[0012] (6) The method for producing sintered ore according to (1) above, wherein only the amount of enriched oxygen supply is adjusted so that the oxygen consumption rate becomes a desired value.

[0013] (7) The method for producing sintered ore according to (1) above, wherein the desired oxygen consumption rate is 0.20 Nm 3 / min or more and 0.25 Nm 3 / min or less.

[0014] (8) The desired oxygen consumption rate is obtained by performing sintering tests with various values of the oxygen supply rate using the carbon material of the target, and in the first relationship which is the relationship between the sintering rate and the oxygen consumption rate and the second relationship which is the relationship between the finished product yield and the oxygen consumption rate, it is above the oxygen consumption rate at which at least one of the sintering rate and the finished product yield saturates as the oxygen consumption rate increases. The method for producing sintered ore according to (1) above.

Advantages of the Invention

[0015] According to the present application, when producing sintered ore with a sintering machine, it is possible to provide a method for producing sintered ore in which oxygen enrichment is performed under more appropriate conditions according to the type of carbon material.

Brief Description of the Drawings

[0016] [Figure 1]This figure shows an example of the configuration of a sintering machine using the sintering ore manufacturing method of this embodiment. [Figure 2] This figure shows the relationship between the oxygen consumption rate and the oxygen supply rate obtained in the example. [Figure 3] This figure shows the relationship between the sintering rate and the oxygen consumption rate obtained in the examples. [Figure 4] This figure shows the relationship between the yield of the finished product and the oxygen consumption rate obtained in the example. [Figure 5] This figure shows the relationship between the production rate and oxygen consumption rate obtained in the example. [Modes for carrying out the invention]

[0017] (First embodiment) The method for manufacturing sintered ore according to this embodiment will be described with reference to the drawings. Figure 1 is a diagram showing an example of the configuration of a sintering machine 1 for manufacturing sintered ore using the method for manufacturing sintered ore according to this embodiment. The method for manufacturing sintered ore according to this embodiment is a method for manufacturing sintered ore using a sintering machine 1, using iron ore and a sintering carbon material (hereinafter also simply referred to as "carbon material") as raw materials, and is a method for manufacturing sintered ore in which oxygen enrichment is performed by blowing oxygen into the air (atmosphere) drawn in during sintering.

[0018] The configuration of the sintering machine 1 will now be described. The sintering machine 1 is a Dwight-Royd type sintering machine. The sintering machine 1 is equipped with a main exhaust fan 2, a main exhaust flue 4, a wind box 6, a sintering bed (sintering layer) 8, an ignition furnace 10, a charging hopper 12, an oxygen flow rate control valve 14, an oxygen flow meter 16, an oxygen injection hood 18, an anemometer 20, and the like. Oxygen enrichment is performed by supplying oxygen from the oxygen injection hood 18. The oxygen flow meter 16 measures the enriched oxygen supply amount, which is the flow rate of oxygen injected from the oxygen injection hood 18. The anemometer 20 measures the wind speed in the oxygen enrichment region, which is the area directly below the oxygen injection hood 18 where oxygen injection takes place. The enriched oxygen supply amount and the wind speed are used in the method of manufacturing sintered ore in this embodiment.

[0019] Next, a method for manufacturing sintered ore will be described. The method for manufacturing sintered ore in this embodiment is a method for manufacturing sintered ore that enriches it with oxygen by blowing in oxygen. The method involves adjusting at least one of the enriched oxygen supply amount Q and the amount of air intake F in the oxygen enrichment region so that the oxygen consumption rate B, which is obtained by multiplying the oxygen supply rate A, which is calculated by the following formula (1) using the enriched oxygen supply amount Q, which is the flow rate of oxygen blowing, and the amount of air intake F in the oxygen enrichment region, which is the area in the sintered layer where oxygen blowing takes place, by the oxygen consumption rate B, which is obtained by multiplying this by the oxygen utilization rate C of the carbon material to be used as a binder, which has been determined in advance, to a desired value. Oxygen supply rate A = Enriched oxygen supply Q + 0.21 × Atmospheric intake F (1) Here, 0.21 in equation (1) represents the oxygen concentration in the atmosphere (21%). As shown in equation (1), the oxygen supply rate A is the total flow rate of oxygen supplied by oxygen injection and the oxygen contained in the atmosphere drawn in in the oxygen-enriched region.

[0020] The inventors' research confirmed that the sintering rate and product yield change depending on the oxygen consumption rate B of the carbon material. Furthermore, the method of this embodiment allows for setting the amount of oxygen enrichment corresponding to the oxygen consumption rate B that results in a better sintering rate and product yield, i.e., the amount of enriched oxygen supplied Q and the amount of atmospheric intake in the oxygen enrichment region (in this embodiment, the area S of the oxygen enrichment region).Therefore, the method of this embodiment allows for oxygen enrichment under optimal conditions according to the combustibility of the carbon material used in the firing process, and enables the production of sintered ore with a good sintering rate and product yield.

[0021] In the method for producing sintered ore according to this embodiment, various carbon materials can be used. The type of carbon material is not particularly limited, but for example, (powdered) coke, biomass char, and coal char can be used. As biomass char, for example, palm kernel shell char (PKS char) produced by heat treatment (dry distillation) of palm kernel shells (PKS) or charcoal produced by dry distillation of wood can be used. Furthermore, a mixture of these carbon materials can be used as the carbon material. In the method of this embodiment, both carbon materials composed of a single type and carbon materials blended with multiple types can be oxygen-enriched to the optimal amount to produce sintered ore.

[0022] The following describes each step of the method of this embodiment. The method for producing sintered ore of this embodiment includes the following steps 1) to 5). 1) Determine the oxygen utilization rate C of the target carbon material. 2) Determine the desired oxygen consumption rate B during sintering using the target carbon material. 3) Determine the oxygen supply rate A in the actual sintering process using the target carbon material. 4) Set the amount of enriched oxygen supplied Q and the amount of atmospheric intake F in the oxygen-enriched region so that the oxygen supply rate A is determined. 5) Perform sintering with the set oxygen enrichment supply amount Q and the amount of air intake F in the oxygen enrichment region.

[0023] The values ​​to be obtained in steps 1) and 2) can be determined by performing a sintering pot test, and values ​​obtained in advance by performing the test may be used in step 3). Also, the order of steps 1) and 2) is not particularly limited; either can be performed first or in parallel. Furthermore, the oxygen enrichment in the method for producing sintered ore in this embodiment is based on the following conditions, which have been conventionally considered efficient: (i) oxygen enrichment starts substantially immediately after ignition, (ii) the oxygen enrichment time is 0.5 to 5 minutes, or (iii) the oxygen enrichment area ratio (= area of ​​the oxygen enrichment region (oxygen blowing hood 18) / effective area of ​​the sintering machine) is 1 to 12.5%.

[0024] Step 1) is to determine the oxygen utilization rate C of the carbon material to be used. This oxygen utilization rate C (volume %) is calculated using the oxygen supply rate A [Nm³]. 3 [ / min], oxygen consumption rate B [Nm] 3 There is a relationship between [ / min] and the following equation (2). Oxygen supply rate A = Oxygen consumption rate B / Oxygen utilization rate C (2)

[0025] The oxygen utilization rate C can be determined by performing a sintering pot test as follows. First, the target carbon material, iron ore, and auxiliary materials are mixed. The carbon material should be tested in the actual state of the carbon material to be used (mixture, particle size, etc.). For example, if using carbon material made by mixing powdered coke with a specific biomass carbon at a ratio of 30% by mass, then carbon material mixed at that ratio should be used. Then, air and oxygen are supplied to the sintering pot to sinter the raw materials and produce sintered ore. During this process, sintering tests are performed by supplying oxygen at various oxygen supply rates A, and the oxygen consumption rate B is determined for each oxygen supply rate A. An approximation curve is obtained from the relationship between the oxygen consumption rate B and the oxygen supply rate A. The approximation curve can be obtained, for example, by performing regression analysis on the relationship (plot) between the determined oxygen consumption rate B and the oxygen supply rate A.

[0026] Furthermore, equation (2) above can be rewritten as equation (2a) below. Oxygen consumption rate B = Oxygen utilization rate C × Oxygen supply rate A (2a) As shown in equation (2a), the slope of the approximation curve relating the oxygen consumption rate B and the oxygen supply rate A is the oxygen utilization rate C. Therefore, the oxygen utilization rate C can be determined by finding the slope of the approximation curve of this relationship. The oxygen supply rate A and the oxygen consumption rate B are obtained by the sintering pot test as follows.

[0027] First, the oxygen supply rate A can be calculated using equation (1) as described above, but in the sintering pot test, the amount of enriched oxygen supplied to the sintering layer Q [Nm³] 3 [ / min] and the amount of air supplied F'[Nm³] corresponding to the amount of air drawn in F. 3The oxygen supply rate A can be calculated by adding the flow rate (oxygen supplied from the atmosphere), which is obtained by multiplying the oxygen concentration (0.21) by the oxygen concentration ( / min) (i.e., A = Q + 0.21F'). Therefore, by changing the enriched oxygen supply rate Q, various oxygen supply rates A can be obtained. Also, if the firing airflow rate in the sintering pot is kept constant, the amount of enriched oxygen supplied during the evaluation period can be changed by keeping the oxygen concentration constant and changing the oxygen enrichment time.

[0028] The oxygen consumption rate B in the sintering pot test can be determined by subtracting the oxygen release rate D in the exhaust gas from the oxygen supply rate A of oxygen supplied to the sintering layer during the 3 minutes from the end of ignition in the sintering pot test (i.e., B = AD). The oxygen supply rate A can be determined by the method described above. The oxygen release rate D in the exhaust gas can be determined from the measurements of the exhaust gas flow meter and exhaust gas analyzer (oxygen concentration meter) located on the blower side that draws in from the downstream side of the sintering pot. Specifically, the oxygen release rate D can be determined by multiplying the exhaust gas flow rate by the exhaust gas oxygen concentration (D = exhaust gas flow rate × exhaust gas oxygen concentration).

[0029] In step 2), the desired (appropriate) oxygen consumption rate B for the target carbon material is determined from the results of the same sintering pot test. Specifically, the relationship between the sintering rate [mm / min] and the oxygen consumption rate B (first relationship) and the relationship between the product yield (mass%) and the oxygen consumption rate B (second relationship) are determined from the results of the sintering pot test performed at various oxygen supply rates A. Then, based on these relationships, the oxygen consumption rate B is determined such that the values ​​of the sintering rate and product yield become the desired values ​​(satisfies the desired conditions). In addition to these relationships, the oxygen consumption rate B may also be determined using the relationship between the production rate and the oxygen consumption rate B. Furthermore, as the first relationship, instead of the relationship between the sintering rate and the oxygen consumption rate B, the relationship between the production rate and the oxygen consumption rate B, which yields generally similar results, may be used.

[0030] As shown in the examples described later, it was found that as the oxygen consumption rate B increases, the sintering rate and product yield tend to increase and then saturate. Furthermore, it was found that the product yield tends to decrease when the oxygen consumption rate is further increased from the saturated state. By comprehensively considering the relationship between the sintering rate and product yield and the oxygen consumption rate, the oxygen consumption rate corresponding to the target sintering rate and product yield can be determined as the desired oxygen consumption rate B. For example, the desired oxygen consumption rate can be set in a range above the oxygen consumption rate near the point where the increase in at least one of the sintering rate or product yield saturates (saturation point). Alternatively, the desired oxygen consumption rate can be set in a range above the oxygen consumption rate at which both the increase in sintering rate and the increase in product yield saturate. Furthermore, from the viewpoint of cost-effectiveness, it can be set in a range below the oxygen consumption rate just before the product yield begins to decrease.

[0031] Here, the sintering rate can be calculated by dividing the raw material layer thickness by the sintering time, where the sintering time is defined as the time from the start of ignition to the time when the exhaust gas temperature reaches its peak in the sintering pot test. The yield of the finished product is determined by dropping the sintered cake obtained after firing in the sintering test from a height of 2m four times, and recovering the particle size + 5mm (over 5mm) excluding the bedrock ore. The mass of this recovered portion is then defined as the yield of the finished product, and using the mass of the sintered cake (the total mass of the sintered cake) and the mass of the bedrock ore, Product yield (mass%) = finished product mass / (sintered cake mass - bedding ore mass) The formula can be calculated to find the answer.

[0032] The optimal oxygen consumption rate can vary depending on the type of carbon material and other sintering conditions. However, as shown in the examples described later, studies on multiple types of carbon materials revealed that an oxygen consumption rate B of 0.20 Nm³ is preferable. 3 It can be set to 0.20 Nm³ or more. 3 Below 0.20 Nm / min, as the oxygen consumption rate B increases, the sintering rate and product yield improve. 3This is because the sintering rate and product yield saturate when the oxygen consumption rate B exceeds / min. 3 It can be less than / min. 0.25Nm 3 This is because keeping the rate below / min prevents a decrease in yield that would result from an excessive increase in combustion speed.

[0033] This preferred range of oxygen consumption rate can be applied in the operation of sintering ore production that involves oxygen enrichment. However, the preferred oxygen consumption rate may deviate from the aforementioned numerical range if the environment in which the carbon material burns, i.e., the carbon material's presence or combustion temperature, differs from the norm. For example, this may occur if the raw material particle size composition differs significantly due to the use of a large amount of pellet feed, or if the amount of carbon material added is significantly changed. In these cases, the method of this embodiment can be used to determine a more appropriate oxygen supply amount and perform oxygen enrichment before sintering.

[0034] It is preferable that the firing conditions in the actual sintering process using the target carbon material and the firing conditions in the sintering pot test in steps 1) and 2) be the same, but they do not necessarily have to be the same.

[0035] In step 3), the oxygen supply rate A corresponding to the determined oxygen consumption rate B is calculated using the oxygen utilization rate C of the target carbon material obtained in step 1) and the oxygen consumption rate B determined in step 2). This oxygen supply rate A is the oxygen supply rate when the sintering process is carried out in the sintering machine 1 using the target carbon material. The oxygen supply rate A can be obtained by substituting the determined oxygen consumption rate B and the obtained oxygen utilization rate C into the above equation (2).

[0036] In step 4), the amount of enriched oxygen supplied Q and the amount of air intake F in the oxygen enrichment region are set based on the determined oxygen supply rate A. Specifically, the amount of enriched oxygen supplied Q and the amount of air intake F (area S of the oxygen blowing hood) are set based on the above equation (1) so that the determined oxygen supply rate A is achieved. At this time, the determined oxygen supply rate A can be achieved by adjusting at least one of the amount of enriched oxygen supplied Q and the amount of air intake F in the oxygen enrichment region. For example, if the amount of air intake F is fixed in the sintering machine 1, the amount of enriched oxygen supplied Q can be adjusted. If the amount of air intake F is variable, the amount of air intake F can be adjusted and the amount of enriched oxygen supplied Q can be kept constant at a predetermined amount. Also, if both are adjustable, both can be adjusted.

[0037] The enriched oxygen supply amount Q can be adjusted by the oxygen flow rate control valve 14 of the sintering machine 1, and the supply amount can be confirmed by the oxygen flow meter 16.

[0038] Atmospheric intake F[Nm³] in the oxygen-enriched region 3 [ / min] is the area S[m²] of the oxygen blowing hood 18. 2 It can be calculated using the following equation (3) with the suction air velocity f [Nm / min]. Atmospheric intake volume F = Area S of oxygen injection hood (oxygen enrichment region) × Suction wind velocity f (3) The area S of the oxygen injection hood 18 is the area of ​​the hood region directly below the oxygen injection hood 18, as shown by the double arrow in Figure 1, and is the area of ​​the oxygen enrichment region where oxygen is injected and drawn into the sintering bed 8. As will be described later, the suction wind speed f is usually fixed, so if the area S of the oxygen injection hood 18 is variable, the amount of atmospheric air drawn in F in the oxygen enrichment region can be adjusted by changing the area S. For example, if the range in which oxygen is injected within the hood can be changed, or if the oxygen injection hood 18 can be replaced with a hood of a different area, the area S can be changed by these methods.

[0039] The suction wind velocity f is the wind velocity of the gas (atmosphere and enriched oxygen) drawn into the sintering bed 8 within the area S of the oxygen blowing hood 18 in the sintering machine 1. The suction wind velocity f can be measured by an anemometer 20 placed between the sintering bed 8 and the oxygen blowing hood 18. As the anemometer 20, a known anemometer such as the one described in Japanese Utility Model Publication No. 58-030198 can be used. The anemometer 20 may be placed on the sintering bed 8 to take measurements and then retrieved, or it may be fixed in a predetermined position where the wind velocity can be measured. Normally, in the operation of the sintering machine 1, the amount of suction by the main exhaust fan 1 is fixed and the suction wind velocity f is constant, so it is sufficient to measure and confirm the wind velocity once. Of course, if the suction wind velocity f is variable, the amount of atmospheric suction F may be adjusted by changing the suction wind velocity.

[0040] As described above, (a) Adjustment of oxygen enrichment supply Q (b) Adjustment of atmospheric intake volume F by adjusting the area S of the oxygen blowing hood (c) Adjustment combining (a) and (b) By one of the following methods, the oxygen supply rate supplied to the sintering bed 8 in the sintering machine can be set to the determined oxygen supply rate A. If the area S (amount of air intake F) of the oxygen blowing hood in (b) cannot be adjusted, only the enriched oxygen supply amount Q in (a) should be adjusted to set the target oxygen supply rate A.

[0041] Then, in step 5), the sintering machine is operated under the set conditions of the enriched oxygen supply amount Q and the amount of air intake F in the oxygen enrichment region to produce sintered ore. The above is the method for producing sintered ore according to this embodiment.

[0042] According to this embodiment, sintered ore can be produced by supplying oxygen to the target carbon material at an appropriate oxygen supply rate. Therefore, regardless of the type of carbon material, sintered ore can be produced by performing oxygen enrichment that results in a good sintering rate and product yield.

[0043] (Second embodiment) In this embodiment, the amount of air intake F in equation (1) above is determined by a method different from that of the first embodiment. In the first embodiment, the wind speed in the oxygen enrichment region was measured by an anemometer 20 above the sintering bed, and the amount of air intake F was determined by equation (3). In this embodiment, instead of measuring the wind speed f, the amount of air intake F is determined using the airflow rate of the sintering machine 1, the air leakage rate, the area S of the oxygen injection hood, and the effective area of ​​the sintering machine. Specifically, the amount of air intake F can be determined by the following equation (4). Atmospheric intake volume F = (Area of ​​oxygen blowing hood S / Effective area of ​​sintering machine a) × (1 - ρ / 100) × Airflow rate of sintering machine V (4)

[0044] The area S of the oxygen injection hood is as described in the first embodiment. ρ is the air leakage rate (volume %) in the sintering machine 1, and the airflow rate V [Nm³] of the sintering machine. 3 [ / min] is the main exhaust air volume measured in the main exhaust fan 2. The main exhaust air consists of leak air and effective air. If we define leak air as air entering from openings in the equipment, etc., and effective air as the exhaust gas after firing observed directly below the sintering material layer, the leak rate ρ is expressed by the following equation (5). Air leakage rate = (O2 concentration in exhaust gas at main exhaust fan - effective air O2 concentration) ÷ (air leakage O2 concentration - effective air O2 concentration) (5) Each O2 concentration can be measured using an oxygen concentration meter. The air leakage rate ρ varies depending on the sintering machine. Therefore, using equation (4) above, the air volume obtained by subtracting the air leakage rate from the total air volume V using the air leakage rate ρ, and multiplying this by the ratio of the oxygen injection hood (oxygen enrichment region) area S to the effective sintering area a, can be used to determine the amount of air drawn in F in the oxygen enrichment region.

[0045] According to the method of this embodiment, the amount of air drawn in F can be calculated using the airflow rate V and air leakage rate ρ that can be confirmed in the sintering machine 1, even without installing an anemometer 20. This method also allows for oxygen enrichment and the production of sintered ore with a good sintering rate and product yield, regardless of the type of carbon material. [Examples]

[0046] This embodiment will be further explained by the examples. Sintering pot tests were performed on various carbon materials to determine the relationship between the oxygen consumption rate B and the oxygen supply rate A, and it was confirmed that the oxygen utilization rate C could be derived from this relationship. In addition, in the sintering pot tests, the relationship between the sintering rate and the oxygen consumption rate B, the relationship between the finished product yield and the oxygen consumption rate B, and the relationship between the production rate and the oxygen consumption rate B were determined for various carbon materials, and it was confirmed that the oxygen consumption rate B could be determined from these relationships.

[0047] (Sintering test) The sintering pot test was conducted using a sintering pot with a diameter of 300 mm and a height of 500 mm. Samples were prepared with different carbon materials blended as sintering raw materials, and each was subjected to a sintering pot test. The sintering raw materials used and their blending ratios are shown in Table 1. In all samples, the blending of raw materials other than the type of carbon material was the same. The total of the new raw materials (iron ore and auxiliary materials) was set at 100% by mass, with 4.5% by mass (extra) of carbon material (coagulant) and 15.0% by mass (extra) of returned ore blended in. Iron ore A to E were each from different origins. Two types of carbon materials with different burning rates were used. One was a carbon material made only from powdered coke (carbon material 1), and the other was a carbon material (carbon material 2) made by mixing powdered coke with 30% biomass carbon (oil palm kernel shell carbon (PKS carbon)). Both carbon materials had a particle size of -5 mm (below a 5 mm sieve).

[0048] [Table 1]

[0049] In the sintering pot test, the firing conditions involved supplying oxygen and air at a predetermined oxygen supply rate immediately after ignition and allowing it to be drawn in for a predetermined time. After that, the oxygen supply was stopped until sintering was complete, and only air was drawn in. Sintering tests were conducted using the aforementioned samples for each case where the oxygen concentration in the gas supplied during oxygen enrichment (air + enriched oxygen) was 30 vol% and 40 vol%. The oxygen concentration was adjusted by mixing air and oxygen gas. The oxygen concentration in the air was set to 21 vol%. Table 2 shows the carbon material used in the sintering pot test and the oxygen concentration during oxygen enrichment.

[0050] [Table 2]

[0051] (Derivation of oxygen utilization rate) Under the above test conditions, sintering pot tests were conducted for various values ​​of oxygen supply rate A by changing the amount of enriched oxygen Q, and the relationship between oxygen consumption rate B and oxygen supply rate A was determined. In the tests, the amount of enriched oxygen Q was changed by changing the oxygen enrichment time during which gas of the above oxygen concentration was supplied. That is, the amount of enriched oxygen Q was changed by keeping the firing airflow constant and varying the oxygen enrichment time between 0 and 3 minutes from the end of firing time, with the evaluation time being 3 minutes from the end of firing time. This changed the oxygen supply rate A during that evaluation time to various values. For example, if the oxygen concentration of the gas during oxygen enrichment is 30%, and enrichment occurs only for the first minute of the 3-minute evaluation time, the amount of enriched oxygen Q can be calculated as follows: Q = (oxygen concentration - 21%) × oxygen enrichment time / evaluation time × firing airflow = (30% - 21%) × 1 / 3 × firing airflow. Then, by substituting the calculated amount of oxygen Q into equation (1), the oxygen supply rate A can be determined. In this case, the amount of air intake F in equation (1) can be calculated using the amount of air used for firing.

[0052] The oxygen consumption rate B was calculated by subtracting the oxygen release rate in the exhaust gas from the oxygen supply rate A during the 3-minute evaluation period. The oxygen release rate in the exhaust gas was determined by calculating the exhaust gas flow rate × exhaust gas oxygen concentration from the measurements taken by the exhaust gas flow meter and the exhaust gas analyzer (oxygen concentration meter). The exhaust gas oxygen concentration used was the oxygen concentration measured during oxygen enrichment.

[0053] Figure 2 shows the relationship between the oxygen consumption rate B and the oxygen supply rate A, obtained by the above method. Approximate curves were obtained for each of these relationships, and the oxygen utilization rate C was determined from the slope of these curves. For carbon material 1, the oxygen utilization rate C was 51% at both 30% and 40% oxygen concentrations. For carbon material 2, the oxygen utilization rate C was 55% at both 30% and 40% oxygen concentrations. Thus, it was confirmed that the oxygen utilization rate C of the target carbon material can be determined by the sintering pot test.

[0054] (Determination of oxygen consumption rate B) In the above sintering pot test, the sintering rate, product yield, and production rate were determined for various oxygen supply rates A. The sintering rate [mm / min] was calculated by dividing the raw material layer thickness by the sintering time, with the sintering time being defined as the time from the start of ignition to the time when the exhaust gas temperature reached its peak. The product yield was determined by dropping the obtained sintered cake from a height of 2m four times after firing, and using the mass recovered from particles with a particle size of +5mm (over 5mm), excluding the bedrock, as the product yield. Product yield (mass%) = finished product mass / ((sintered cake mass) - (bedding ore mass)) The production rate was calculated based on the bottom surface area (baking area) of the pot (1 m²). 2 This represents the sintered production mass [t] per day (D), Production rate [t / Dm 2 ] = formed mass [t] / (sintering time [D] x pot bottom area [m 2 ]) This was calculated and determined.

[0055] The relationship between the determined sintering rate, product yield, and production rate was calculated using the method described above, specifically the relationship between the sintering rate and the oxygen consumption rate B. Figure 3 shows the relationship between the sintering rate and the oxygen consumption rate B, Figure 4 shows the relationship between the product yield and the oxygen consumption rate B, and Figure 5 shows the relationship between the production rate and the oxygen consumption rate B.

[0056] From the relationship between sintering rate and oxygen consumption rate B in Figure 3, we were able to confirm the oxygen consumption rate at which the sintering rate saturates. Similarly, from the relationship between product yield and oxygen consumption rate B in Figure 4, we were able to confirm the oxygen consumption rate at which the product yield saturates. Therefore, for example, the oxygen consumption rate corresponding to the target sintering rate and product yield can be determined as the desired oxygen consumption rate B. By substituting the determined oxygen consumption rate B and the oxygen utilization rate C obtained above into equation (2), the oxygen supply rate A can be obtained. Then, by adjusting the enriched oxygen supply amount Q and the amount of atmospheric intake F in the oxygen enrichment region and supplying oxygen at the determined oxygen supply rate A to produce sintered ore, sintering can be performed with an appropriate amount of oxygen enrichment.

[0057] Furthermore, the following trends were also confirmed from Figures 3-5. First, regarding the sintering rate in Figure 3, the oxygen consumption rate was 0.20 Nm³ for all types of carbon materials. 3 Below 0.25 Nm³, the sintering rate increased significantly as the oxygen consumption rate increased. 3 Above / min, the sintering rate increased only slightly or remained almost unchanged as the oxygen consumption rate increased. For the yield of the finished product in Figure 4, for all types of carbon material, the oxygen consumption rate was 0.20 Nm³. 3 Below 0.25 Nm³, the yield of finished products improved as the oxygen consumption rate increased. 3 Above 0.20 Nm³, the yield of finished products decreased slightly as the oxygen consumption rate increased. Regarding the production rate in Figure 5, the change in sintering rate accounts for the majority of the changes, and therefore the trend was the same as that of the sintering rate. Thus, when the oxygen consumption rate was 0.20 Nm³, 3 / min or more 0.25Nm 3 It was confirmed that a range of / min or less is preferable. [Explanation of Symbols]

[0058] 1. Sintering machine 2 Main exhaust fan 8 Sintering bed 14. Oxygen flow control valve 16. Oxygen flow meter 18. Oxygen Injection Hood 20 Anemometers

Claims

1. A method for producing sintered ore that is oxygen-enriched, The oxygen supply rate, which is determined by the following equation (I), is calculated using the oxygen enrichment supply amount, which is the flow rate of oxygen injection, and the amount of air drawn into the oxygen enrichment region, which is the area in the sintered layer where oxygen injection takes place. The oxygen utilization rate of the carbon material to be used as a setting agent, A method for producing sintered ore, characterized by adjusting at least one of the enriched oxygen supply amount and the amount of atmospheric intake in the oxygen enrichment region so that the oxygen consumption rate obtained by multiplying by a value becomes a desired value, and supplying oxygen at an oxygen supply rate corresponding to the desired oxygen consumption rate to produce sintered ore. A=Q+0.21×F (I) Here, A [Nm ３ [ / min] is the oxygen supply rate, Q [Nm] ３ [ / min] is the amount of enriched oxygen supplied, F [Nm] ３ [ / min] represents the amount of atmospheric intake in the oxygen-enriched region.

2. The method for producing sintered ore according to claim 1, characterized in that the oxygen utilization rate is the slope of an approximate curve relating the oxygen consumption rate and the oxygen supply rate, which is obtained by performing sintering tests using the target carbon material while varying the oxygen supply rate to various values.

3. The method for producing sintered ore according to claim 1, characterized in that the desired oxygen consumption rate is the oxygen consumption rate corresponding to the target sintering rate and the target yield in the first relationship, which is the relationship between sintering rate and oxygen consumption rate, and the second relationship, which is the relationship between product yield and oxygen consumption rate, which are obtained by performing sintering tests using the target carbon material while varying the oxygen supply rate to various values.

4. The method for producing sintered ore according to claim 1, characterized in that the amount of air drawn in the oxygen-enriched region is determined by multiplying the area of ​​the oxygen-enriched region by the oxygen suction velocity in the oxygen-enriched region.

5. The method for producing sintered ore according to claim 1, characterized in that the amount of air drawn in the oxygen-enriched region is determined by the following formula (II). F=(S / a)×(1-ρ / 100)×V (II) Here, F[Nm ３ [ / min] is the amount of atmospheric intake in the oxygen-enriched region, S [m ２ ] represents the area of ​​the oxygen-enriched region, a [m²] ２ ] is the effective area of ​​the sintering machine, ρ (volume %) is the air leakage rate in the sintering machine, V [Nm ３ [ / min] is the airflow rate of the sintering machine.

6. The method for producing sintered ore according to claim 1, characterized in that only the amount of enriched oxygen supplied is adjusted so that the oxygen consumption rate reaches a desired value.

7. The desired oxygen consumption rate is 0.20 Nm ３ / min or more and 0.25 Nm ３ / min or less, and the method for producing sintered ore according to claim 1 is characterized by this.

8. The method for producing sintered ore according to claim 1, characterized in that the desired oxygen consumption rate is at or above the oxygen consumption rate at which the increase in at least one of the sintering rate and the product yield saturates, in the first relationship, which is the relationship between the sintering rate and the oxygen consumption rate, and the second relationship, which is the relationship between the product yield and the oxygen consumption rate, which are determined by performing sintering tests using the target carbon material while varying the oxygen supply rate to various values.

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