JP2006291292A - Method for charging high crystallized water-containing ore into bell-less blast furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for charging high crystallized water-containing ore into a bell-less blast furnace by which the high crystallized water-containing ore can stably and effectively be used while securing air flowability in the furnace even when the injection quantity of pulverized coalis changed. <P>SOLUTION: (1) In the method for charging the ore into the bell-less blast furnace by dividing the ore into two batches, the high crystallized water-containing ore is divided into respective batches and then charged. (2) In the method for charging the ore into the bell-less blast furnace by dividing the ore into two batches, the charging ratios of the high crystallized water-containing ore charged in first batch and the second batch (A(%) and B(%)) are controlled to satisfy inequality 1 (A≤-0.05×PCR+15) and inequality 2 (B≤3) in accordance with the pulverized coal injecting quantity PCR (kg/pt). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for charging ores in a bell-less blast furnace in which ores are divided and charged in two batches, and more specifically, the high-crystal water-containing ores containing 3.5% by mass or more of crystal water are charged in each batch. The present invention relates to an ore charging method capable of stably using ore containing high crystal water without deteriorating the air permeability of the blast furnace by adjusting the charging ratio according to the amount of pulverized coal injected.

  In blast furnace operation, in general, coke as a reducing material and heat source from the upper part of the furnace, and sintered ore, pellets and lump ore as iron sources (hereinafter these iron sources are referred to as “ores”) are alternately layered. The hot air is blown from the tuyeres at the bottom of the furnace and pulverized coal is blown in at the same time. Note that the amount of pulverized coal blown is usually expressed in terms of blown mass (kg) per 1 t (tons) of pig iron, and is expressed in (kg / t) in the present invention.

  In order to maintain the stable operation of the blast furnace, it is necessary to ensure good air permeability and stabilize the gas flow in the furnace (that is, secure a stable central gas flow and furnace wall gas flow). The air permeability in the furnace is largely influenced by the properties of the raw materials (coke and ore), the particle size, and the amount of charge. In addition, the raw material is charged from the top of the furnace, that is, charged into the furnace. The distribution of raw materials (hereinafter also referred to as “charge distribution”) greatly depends.

  As for the control of the charge distribution, conventionally, the control of the mass ratio of ore and coke in the radial direction of the blast furnace (hereinafter also referred to as “O / C”), or the furnace of the iron source material such as sintered ore. Control of particle size deviation in the radial direction (for example, coarse particles are distributed in the furnace center and fine particles are distributed in the furnace wall) is most often used. By adjusting the distribution of these charges, a stable central flow and a moderate peripheral flow can be secured.

  For example, in the case of a bell-less blast furnace, in order to obtain a stable gas flow by adjusting the particle size, a method is adopted in which ore charged as one layer is divided into two or more batches and charged according to particle size. In addition, in the first batch charging, the O / C in the center of the furnace is charged to be small, and the finer raw material, the raw material with poor hot properties, etc. are mixed in the second batch ore, and the furnace wall portion. When the material is charged, a stable gas flow can be obtained even while using a raw material with poor properties.

  Further, in recent years, ore with a high crystal water content (ores with a crystal water content of 3.5% by mass or more) has been used for the purpose of cost rationalization.

  For example, Patent Document 1 discloses a blast furnace operating method in which a polycrystalline water-containing iron raw material is mixed and charged in advance in iron ore, or a polycrystalline water-containing iron raw material is charged alone. This method is a method for suppressing the rise in the furnace top gas temperature accompanying the increase in the amount of pulverized coal injection by the heat required for heating and evaporation of the crystal water in the ore.

  Patent Document 2 discloses a method of operating a blast furnace in which the heat flow ratio (ratio of solid unit heat quantity to gas unit heat quantity in the blast furnace shaft portion) is 0.80 or less, and the particle size composition is 80% by mass of particles having a particle size of 5 mm or more. As mentioned above, the operation method which lowers | hangs a furnace top gas temperature is disclosed by charging into a blast furnace the block ore whose crystallization water content rate is 3.5 mass% or more as a part of main raw materials. The method disclosed here controls the furnace top gas temperature by adjusting the charging amount of the ore containing high crystal water according to the value of the heat flow ratio.

  Furthermore, in Patent Document 3, when using a porous block ore having a crystal water of 3% or more, a porous block ore having a particle size of 3 mm or less and 1% or less and a sintered ore are charged into a blast furnace furnace. Operation method, and reduced pulverization index of sintered ore (meaning pulverization rate after reduction (-3 mm%) defined by JIS M 8720, abbreviated as “RDI”), low temperature reduction zone in furnace Discloses an operation method for adjusting the amount of the lump ore used according to the residence time of the charge.

  However, in the methods disclosed in Patent Documents 1 to 3 above, in recent years, the amount of high crystallization water contained in accordance with the degree of the amount of pulverized coal injection that tends to increase the amount of blown air and generally deteriorate the air permeability in the furnace. There is no mention of an effective method of charging ore.

JP 2001-140007 (Claims, paragraphs [0009] and [0010]) JP 2001-144219 A (Claims and paragraphs [0022] to [0028]) JP-A-4-263003 (Claims [0004] and [0005]) Akira Mochizuki, Tatsunori Murai, Yoshizumi Kawaguchi, Yuji Iwanaga: Iron and Steel, Vol. 72 (1986) p1855-186, "Application of high temperature property test results to blast furnace operation analysis and sinter quality design"

  As described above, in the blast furnace use technology for ore containing high crystal water, there are many documents disclosing methods for suppressing the furnace top temperature and adjusting the massive zone and the heat preservation zone. However, the ore containing high crystal water has a higher RDI value and KS value described in Non-Patent Document 1 in which the ventilation resistance at the lower part of the blast furnace is indexed, compared to ores generally used in a blast furnace. In reality, it is a raw material that is difficult to increase in use stably in a blast furnace. This is because if the air permeability in the furnace deteriorates, it is difficult to continue the stable operation of the blast furnace, and the planned production volume cannot be maintained.

  Therefore, deterioration of furnace breathability must be avoided, and it will be difficult to increase both the amount of pulverized coal injection and the amount of ore containing high crystal water when expanding the pulverized coal injection in the future. It is expected to be.

  As already mentioned, Patent Document 1 discloses a technique for increasing the amount of ore containing high crystal water as a countermeasure for increasing the temperature at the top of the furnace accompanying the increase in the amount of pulverized coal injection, but this technique improves the operation of the blast furnace. There are few elements and there is a high risk of causing deterioration of the air permeability of the blast furnace.

  Similarly to the method disclosed in Patent Document 1, the method disclosed in Patent Document 2 is also a method of simply decreasing the furnace top gas temperature by increasing the amount of ore containing high crystal water. No consideration is given to the deterioration of internal air permeability, and it is difficult to say that this is a realistic method.

  Furthermore, the method disclosed in Patent Document 3 is a method of adjusting the amount of ore containing high crystal water according to the RDI value of the sintered ore and the residence time of the charge in the low temperature reduction zone in the furnace. However, the value of RDI fluctuates from day to day, and it is not realistic to adjust the amount of ore used according to the fluctuation. It is also difficult to meticulously measure the position of the low-temperature reduction zone in the furnace with a daily pitch.

  Further, no suggestion is given from the viewpoint of increasing the amount of ore charging containing high crystal water that impairs the air permeability under the increase in the amount of pulverized coal injection that tends to deteriorate the air permeability.

  The present invention has been made in view of the above-mentioned problems, and the problem is that by adjusting the charging amount of ore containing high crystal water in each batch of ore according to the amount of pulverized coal injection, Even when the amount of coal injection changes, the high crystal water-containing ore to the bell-less blast furnace that can stably and efficiently use ore the high crystal water-containing ore without hindering air permeability and unloading in the blast furnace. It is to provide a charging method.

  In order to solve the above-mentioned problems, the present inventors conducted a high-temperature load softening test described later and a test operation in which a high-crystal-water-containing ore is charged into a bell-less blast furnace, and analyzed the results. ) To (d) were obtained and the present invention was completed.

  (A) With an increase in the charging ratio of the high crystal water-containing ore into the ore layer, the high temperature ventilation resistance ((KS value described in Non-Patent Document 1)) increases, and therefore the permeability at the bottom of the blast furnace is Getting worse.

  (B) When ore is divided into two batches and charged into the blast furnace, it is better to divide and charge the high crystal content ore into both batches than to charge only one of the batches. Good air permeability in the blast furnace can be secured.

  (C) When ore containing high-crystal water-containing ore divided into two batches, the first batch contains high-crystal water-containing ore in a wide range with respect to the radial direction of the furnace and with a thin layer thickness. By intensively charging the remaining high crystal water-containing ore into the furnace wall by the second batch, a large amount of high crystal water-containing ore can be stably used without impairing the air permeability in the blast furnace.

  (D) In order to ensure good air permeability in the blast furnace, the charging ratio A (mass of high crystal water containing ore charged in the first batch according to the pulverized coal injection amount PCR (kg / pt) %) And the charging ratio B (mass%) of the ore containing high crystal water charged in the second batch so as to satisfy the relationship represented by the following formulas (1) and (2), respectively. Is preferred.

A ≦ −0.05 × PCR + 15 (1)
B ≦ 3 (2)
The present invention has been completed based on the above findings, and the gist of the present invention lies in the method for charging ores containing high crystal water into the bell-less blast furnace shown in the following (1) and (2).

  (1) In a method for charging ores into a bell-less blast furnace in which ore is divided into two batches and charged in the furnace, the ore containing high crystal water is divided and charged in each batch. A method for charging ore with high crystal water content (hereinafter, also referred to as “first invention”).

  (2) In the method of charging ores into the bell-less blast furnace where the ore is divided into two batches and charged into the furnace, high crystal water content is charged in the first batch and the second batch according to the amount of pulverized coal injection A method for charging ores containing high crystal water into a bell-less blast furnace characterized by adjusting the charging ratio of the ore so as to satisfy the relationship represented by the following formulas (1) and (2) respectively (hereinafter, Also referred to as “second invention”).

A ≦ −0.05 × PCR + 15 (1)
B ≦ 3 (2)
Here, A is the ratio (% by mass) of the amount of ore containing high crystal water charged in the first batch of ore to the total amount of ore charged, and B is the high crystal water charged in the second batch of ore. The ratio (mass%) that the amount of containing ore occupies with respect to the amount of all ores charged, and PCR represent the amount of pulverized coal injected into the blast furnace (kg / pt). In addition, pt represents pig iron 1t (ton).

  In the present invention, “high crystal water-containing ore” means an ore having a crystal water content of 3.5% by mass or more as described above.

  In the following description, “mass%” is also simply expressed as “%”.

  According to the method of the present invention, according to the amount of pulverized coal injected into the bell-less blast furnace, it is possible to adjust the charging amount of ore containing high crystal water to an appropriate amount in each batch of ore. Even in an operation where the amount of coal injection changes, a large amount of ore containing high crystal water can be stably and effectively used while ensuring a good gas flow and unloading in the blast furnace.

  As described above, the present invention is a method for charging high-crystal water-containing ore into a bell-less blast furnace in which high-crystal water-containing ore is divided into two batches and charged, and preferably, the high-crystal water-containing ore is charged in the first batch. To a bell-less blast furnace where the charging ratio of the ore containing crystal water is adjusted to be less than the upper limit of the charging ratio determined by the amount of pulverized coal injected into the blast furnace and the charging ratio in the second batch is adjusted to 3% or less. This is a method for charging ore containing high crystal water. The method for charging the ore containing high crystal water according to the present invention will be described in more detail below.

(1) Effect of high-temperature water-containing ore on high-crystal water-containing ores and charging ratio To understand the air-flow characteristics of ores containing high-crystal water, laboratory-scale high-temperature load softening tests were conducted using a vertical electric furnace. The high temperature aeration characteristic of was investigated. Since the details of the test conditions are described in Non-Patent Document 1, only the outline is described here.

In a graphite crucible with an inner diameter of 70 mm having a plurality of holes for gas flow and dripping of melt at the bottom, a sample of coke with a particle size of 10 to 15 mm is used as a lower layer, and an ore with a particle size of 15 to 20 mm. In the upper layer, the ore and coke mass ratio (O / C) is charged so as to have a predetermined value, and is placed in a vertical electric furnace. In these samples, a reducing gas in which the CO concentration gradually increases from 24 to 45% with time and the CO ₂ concentration gradually decreases from 23 to 0% flows at a flow rate of 50 NL / min. While applying a load increasing to 1 MPa, a heating load reduction test was performed in which the temperature was raised to 1600 ° C. in 6 hours, and the pressure loss and the layer thickness change over time of the sample layer were measured. The airflow resistance is obtained by using the pressure loss obtained by the above test and the layer thickness of the sample, and this airflow resistance is integrated over a temperature range from 1000 ° C. to the test end temperature (Tf) to obtain a high temperature airflow resistance (KS value). )

  FIG. 1 is a diagram illustrating a method for calculating a high temperature ventilation resistance (KS value). The high temperature ventilation resistance (KS value) means that the smaller the value, the smaller the ventilation resistance from the softening of the ore to the melt dripping. Therefore, when ores having a large KS value are charged into the furnace, the air permeability in the fusion zone at the bottom of the blast furnace is expected to deteriorate.

  Table 1 shows a comparison of the KS values and RDIs obtained by the above tests for ordinary ores and high crystal water-containing ores.

  As shown in the table, the ore A containing high crystal water is easily reduced to powder and is very inferior in high-temperature air permeability. Therefore, when using ores with high crystal water content that tends to hinder the air permeability of the blast furnace in this way, fully consider its characteristics, and in accordance with the characteristics, an appropriate amount in an appropriate area in the radial direction of the furnace It is only necessary to charge. In addition, in the future, the amount of pulverized coal injection is expected to increase further to the level of 150 to 200 kg / pt. It is necessary to establish an effective charging method for ore containing high crystal water according to the level of quantity.

  Therefore, assuming that the amount of pulverized coal injection in the blast furnace is 100 kg / pt, the O / C value is set to 4.2, and the charging ratio of the ore A containing high crystal water is changed, and the heating load reduction test is performed. The effect on the KS value was investigated. The charging ratio of the high crystal water-containing ore was changed by changing the blending ratio of the high crystal water-containing ore in the sintered ore charged as an upper layer in the graphite crucible.

  The test and evaluation results are shown in Table 2.

  From the results shown in the table, the KS value increases as the charging ratio of the high crystal water containing ore increases. When the charging ratio is 14%, the ratio of the high crystal water containing ore is 4%. It can be seen that the KS value increases by 50% or more compared to the case.

  Accordingly, even in the actual blast furnace, when the charging ratio of the ore containing high crystal water becomes high, the air permeability deteriorates in the cohesive zone region at the lower part of the furnace, and good gas flow in the furnace is inhibited.

(2) Method of dividing and charging high crystal water-containing ore The inventor further examined the method for dividing high crystal water-containing ore into batches based on experience in actual furnace operation and test operation. The present inventors have found that it is preferable to divide and charge the water-containing ore into both batches in order to ensure the air permeability of the blast furnace, rather than charging it into one batch.

  The reason is as described below. That is, the ore containing high crystal water is inferior to the high temperature aeration characteristics as described above, so when it reaches the lower part of the blast furnace due to unloading, it deteriorates the air permeability in the cohesive zone region of the lower part of the furnace, and as a result, the pressure in the lower part of the furnace Increase loss.

  Therefore, as a countermeasure, it is possible to reduce the influence on deterioration of air permeability in the lower part of the blast furnace by introducing ore with high crystal water content over a wide area as much as possible in the radial direction of the furnace, by reducing the layer thickness. it can. In addition, blast furnaces are sometimes charged with fine coke and fine-grained sintered ore placed on the furnace wall for the purpose of appropriately controlling the furnace wall flow. The same effect as when charging fine coke or fine sintered ore into the furnace wall can be obtained by concentrating and charging a small amount of high-crystal water-containing ore with poor characteristics into the furnace wall. Can do.

  FIG. 2 is a diagram schematically showing a longitudinal section of the distribution of high crystal water-containing ore in the blast furnace interior.

  As shown in the figure, the first batch ore layer 2 is formed in the upper part of the coke layer 1 by charging the first batch of ore containing the ore 4 containing high crystal water over a wide range in the furnace radial direction. . The high crystal water-containing ore 4 in the first batch ore layer 2 is distributed and deposited in a relatively wide area in the blast furnace radial direction with a thin layer thickness. A small amount of high crystal water-containing ore 4 is distributed in the second batch ore layer 3 formed on the furnace wall. As a result, a stable central gas flow and an appropriate furnace wall gas flow are ensured.

  As described above, the ore is divided into two batches, and in the first batch, the ore containing high crystal water is wide and thin with respect to the radial direction of the furnace, and the remaining high crystal water containing ore is placed on the furnace wall in the next second batch. By charging in a concentrated manner, a large amount of ore containing high crystal water can be used stably without adversely affecting the air permeability of the blast furnace.

  In addition, in blast furnace mass injection operation in a blast furnace, while continuing the above charging, by reducing the total charging amount of ore containing high crystal water as the pulverized coal injection amount increases, It is assumed that stable use of crystal water-containing ore in the blast furnace can be secured.

  Therefore, as will be described later, a test operation in a blast furnace was performed, and the effect of the division ratio of the high crystal water-containing ore to each charging batch was investigated, and the results shown in the following 1) to 3) were obtained.

1) In order to ensure good air permeability in the blast furnace, the total amount of ore with high crystallization water content ore charged in the first batch of ore according to the pulverized coal injection amount PCR (kg / pt) It is preferable to adjust the ratio A (%) to the ratio so as to satisfy the relationship represented by the formula (1).

A ≦ −0.05 × PCR + 15 (1)
2) Even if the total charging ratio in all batches of high-crystal water-containing ore is the same, the ratio B (%) of the high-crystal water-containing ore charged in the second batch of ore to the total charged ore amount is 3 % Is preferably adjusted so as to satisfy the following.

  3) More preferably, the ratio B (%) should be adjusted to be 2% or less. Therefore, the ratio A (%) should be adjusted so as to satisfy the relationship represented by the following formula (3). Is more preferable.

−0.05 × PCR + 13 <A ≦ −0.05 × PCR + 15 (3)
Here, the case where the high crystal water containing ore charging method of the present invention is further applied to the charging method for dividing the ore into three batches or more will be described.

  First, in dividing the ore containing high crystal water into each batch, the final ore batch is charged with an ore amount of 3% or less. And in the batch from the first batch to the last batch, the charging ratio A (%) is the total ratio of the ore charging with high crystal water content from the first batch to the last batch one batch. In other words, the charging may be performed by adjusting the charging ratio A (%) so as to satisfy the relationship represented by (1) defined in the present invention.

  Thereafter, the above charging operation is repeated, but depending on the transition status of furnace condition management indices such as furnace permeability (blast furnace ventilation resistance index) and number of slips during operation, The charging ratio may be finely adjusted.

In order to confirm the effect of the high crystal water-containing ore charging method of the present invention, the test operation of charging the high crystal water-containing ore under the condition that the pulverized coal injection amount is 120 kg / pt in the blast furnace having a furnace internal volume of 4800 m ^3. We evaluated the effects of operating results such as blast furnace permeability and slip occurrence. The test operation was continuous operation for 5 days per condition, and the average value during the operation was adopted.

  Table 3 shows operation conditions and operation results in the test operation.

  In the table, the blast furnace ventilation resistance index KR is a value calculated by the following equation (4), and the lower the value of KR, the better the air permeability in the blast furnace.

KR = (P _B −P _T ) / L / (kμ ^β ρ ^1−β u ^2−β ) (4)
Where KR is the blast furnace ventilation resistance index (1 / m), P _B and P _T are the blowing pressure and the top pressure (Pa), L is the distance between the tuyere and the top (m), β and k are A constant determined by the form of the gas flow, μ is the gas viscosity (Pa · s), ρ is the gas density (kg / m ³ ), and u is the gas flow velocity (m / s) in the furnace.

  In addition, the criteria for classification by symbols ◎, ○, Δ, and x in the test result evaluation column in the same table are as described in the lower column of Table 3.

  Test numbers 2-1 to 2-5 and 2-7 to 2-11 are examples of the present invention that satisfy the conditions specified in the first invention, and test numbers 2-6 and 2-12 are comparative examples. It is.

  In all of the examples of the present invention, the blast furnace ventilation resistance index KR is 13400 (1 / m) or less which is allowable in the blast furnace, and the number of slip occurrences indicating an unloading abnormality of the charge is 1.6 (times / time). The furnace conditions were favorable.

  On the other hand, in the comparative example, the blast furnace ventilation resistance index KR reached a high 13800 (1 / m) in the blast furnace, and the number of slip occurrences was also increased to 1.8 (times / day). The furnace condition became unstable.

  By arranging the results of Table 3 and adjusting the charging ratio A (%) of the high-crystal water-containing ore of the first batch of ore to a range satisfying the relationship represented by the above formula (1), the blast furnace It was proved preferable because good air permeability and unloading conditions could be secured without greatly affecting the air flow resistance index KR. In the case of Test Nos. 2-3 and 2-9 in which 4% of high-crystal water-containing ore was charged into the second batch of ore even if the total charging ratio of high-crystal water-containing ore was the same, The blast furnace ventilation resistance index KR is increased as compared with the case of test numbers 2-1, 2-2, 2-7, and 2-8 having an input ratio of 3% or less. Accordingly, it has also been found that the ratio B (%) of the high crystallized water-containing ore charged into the second ore batch to the total charged ore is preferably 3% or less.

  FIG. 3 is a chart showing the results of Table 3 as effects of the amount of pulverized coal injection and the ratio of ore charging containing high crystal water in the first ore batch on the blast furnace air permeability evaluation. The symbols ◎, ○, Δ and × in the figure are all synonymous with the symbols used in the test result evaluation column of Table 3. From the results in the figure, the following matters are clear.

  That is, as described in the background art of the present invention, from the viewpoint of cost rationalization, the total charging ratio (A + B) (%) of the ore containing high crystal water is desired to be as large as possible. However, as described above, it is preferable to adjust the charging ratio A (%) in the first batch so as to satisfy the relationship represented by the formula (1). Further, the charging ratio B (%) in the second batch is preferably 3% or less as shown in the results of Test Nos. 2-1, 2-2, 2-7 and 2-8, more preferably As shown in Test Nos. 2-1 and 2-7, it should be 2% or less.

  Therefore, it is more preferable to adjust the charging ratio A (%) in the first batch so as to satisfy the relationship represented by the following expression (3).

−0.05 × PCR + 13 <A ≦ −0.05 × PCR + 15 (3)
The more preferable range described above is indicated by the hatched portion in FIG.

  As explained above, the ore containing high crystal water up to a charging ratio of 3% is deposited on the furnace wall widely and thinly in the second batch, so even if the high temperature ventilation resistance KS value of the ore itself is high, There is no significant effect on the deterioration of air permeability. The remaining ore containing high crystal water can be charged in the first batch of ore according to the value of the pulverized coal injection amount, that is, according to the value of O / C, in a range that does not adversely affect the blast furnace air permeability.

  The reason for this is as follows. That is, the ore containing high crystal water is inferior in high-temperature aeration characteristics, so if it is concentrated and charged in a specific area in the radial direction of the furnace, the air permeability in that area will be extremely deteriorated, increasing the use ratio. I can't. On the other hand, the ore containing high crystal water can be charged uniformly in the radial direction in the furnace by dividing each batch of ore as described above and charging in each batch, so that the radial direction This is because an extremely high ventilation resistance load is not applied to the specific region.

  In many cases, the second batch often uses fine-grained raw materials to control the furnace wall flow. Therefore, in the present invention, by using a high crystal water content ore in a small proportion of 3% or less in this second batch, the high crystal water content ore is used while appropriately controlling the furnace wall gas flow. Is preferable. However, if a large amount of high crystal water-containing ore is charged into the furnace wall, the air permeability at the bottom of the furnace wall deteriorates and it becomes difficult to increase the charging ratio of the high crystal water-containing ore. The charging ratio in two batches is preferably within the above range.

  According to the ore charging method of the present invention, according to the amount of pulverized coal injected into the bell-less blast furnace, the charging amount of ore containing high crystal water can be adjusted and charged in each batch of ore. Therefore, even in blast furnace operation in which the amount of pulverized coal injection changes, the ore containing high crystal water can be stably and effectively used while maintaining a good gas flow and unloading in the blast furnace. Therefore, the ore charging method of the present invention is a bellless blast furnace in which the amount of pulverized coal injection changes, ensuring the air permeability in the furnace, and using a large amount of ore containing high crystal water under stable operation. It can be widely applied as an operation method that can reduce costs.

It is a figure which shows the calculation method of high temperature ventilation resistance (KS value). It is a figure which shows typically the furnace interior distribution of the ore containing high crystal water. It is a figure which shows the influence of the amount of pulverized coal injection | pouring on the air permeability evaluation of a blast furnace, and the ore charging ratio containing a high crystal water in an ore 1st batch.

Explanation of symbols

1: coke layer, 2: first batch ore layer, 3: second batch ore layer,
4: Ore containing high crystal water

Claims (2)

  In a method for charging ores into a bellless blast furnace in which the ore is divided into two batches and charged into the furnace, the ores containing high crystal water is divided into batches and charged into a bellless blast furnace. The charging method of ore containing crystal water. In the method of charging ores into a bell-less blast furnace, in which the ore is divided into two batches and charged into the furnace, the high crystal water-containing ore charged in the first batch and the second batch is charged according to the amount of pulverized coal injection. A method for charging ore containing high crystal water into a bell-less blast furnace, wherein the charging ratio is adjusted so as to satisfy the relationship represented by the following formulas (1) and (2):
A ≦ −0.05 × PCR + 15 (1)
B ≦ 3 (2)
Here, A is the ratio (% by mass) of the amount of ore containing high crystal water charged in the first batch of ore to the total amount of ore charged, and B is the high crystal water charged in the second batch of ore. The ratio (mass%) that the amount of containing ore occupies with respect to the amount of all ores charged, and PCR represent the amount of pulverized coal injected into the blast furnace (kg / pt). In addition, pt represents pig iron 1t (ton).

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