Method for stabilizing and improving furnace charge structure of blast furnace

Abstract

The invention belongs to the technical field of steel smelting, and particularly relates to a method for stabilizing and improving a blast furnace burden structure. Comprising the following steps: (1) determining a batching plan according to mineral powder resources, capacity requirements of each sintering machine, components of sintered ore, a blast furnace burden structure and slag components; (2) burdening is carried out according to a burdening plan during sintering, and stable production is carried out according to a planned capacity demand; and (3) the blast furnace carries out burdening according to the planned furnace charge structure, and when CaO / SiO2 deviates from a target value, adjustment is carried out by adding high-silicon briquette ore or silica. According to the method, a small amount of silica or high-silicon lump ore is consumed by a using end, so that the furnace charge structure is stabilized, a blast furnace slag system is stable, furnace charge TiO2 is stable, the furnace condition of the blast furnace is stable, and the fuel consumption of the blast furnace is not increased but reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of steel smelting, and in particular relates to a method for stabilizing and improving the structure of blast furnace charge. Background Art

[0002] The charge structure of a steel plant's blast furnace is composed of high-basicity sintered ore, low-basicity sintered ore and lump ore in different proportions. The proportion of high-basicity sintered ore is 60%-75%, the proportion of low-basicity sintered ore is 15-35%, and the proportion of lump ore varies between 5-15%. Typical material composition is shown in Table 1:

[0003] Table 1: Composition of high basicity sinter and low basicity sinter

[0004]

[0005] It can be seen from Table 1 that the composition of high-basicity sintered ore is quite different from that of low-basicity sintered ore. High-basicity sintered ore has the characteristics of low grade, low FeO, low MgO, low Al2O3 and low TiO2. The increase and decrease of the proportion of high-basicity sintered ore and low-basicity sintered ore in the charge structure will lead to large fluctuations in the slag CaO / SiO2, MgO / Al2O3 and the TiO2 load entering the furnace.

[0006] The remelting performance of mixed charge is not a simple average of the remelting performance of a single material. According to the results of the sintering cup test, the remelting performance of about 70% high basicity sintered ore + about 30% (low basicity sintered ore + lump ore) is the best, so it is necessary to stabilize the charge structure within this range.

[0007] At present, the general technical scheme for the use of raw materials into the furnace is:

[0008] (1) Based on the ore powder resources, a discussion on ore matching is held to determine the production capacity requirements of each sintering machine, the composition of the sintered ore, the structure of the blast furnace charge, and the composition of the slag. In reality, due to quality inspection, weighing, ore return circulation, and process changes, the deviation between the theoretical calculation and the actual composition is affected. The ironmaking process adjusts the charge structure to achieve the desired slag system, which leads to a deviation in the use of high-basicity sintered ore and low-basicity sintered ore;

[0009] (2) The sintering machine capacity does not match the ironmaking demand, and there is often a situation where one side is abundant and the other side is in short supply. On the one hand, sintering is forced to frequently adjust the capacity coefficient, and on the other hand, the addition of CaO and MgO flux is frequently adjusted, resulting in fluctuations in the composition of the sintered ore;

[0010] (3) The adjustment of blast furnace charge structure is usually based on the premise that the proportion of lump ore remains unchanged. The ratio of high-basicity sintered ore to low-basicity sintered ore is adjusted to achieve the required binary basicity (CaO / SiO2). As the composition of the sintered ore fluctuates, the blast furnace is also frequently adjusted, resulting in large fluctuations in the ratio of high-basicity sintered ore to low-basicity sintered ore entering the furnace, resulting in large fluctuations in the slag composition MgO / Al2O3 and the TiO2 load entering the furnace. The blast furnace production has been in a fluctuating state;

[0011] (4) When the ore powder inventory is low and the grade is low, the high-basicity sintered ore has high SiO2, and the amount of CaO entering the furnace increases. The proportion of high-basicity sintered ore in the blast furnace is often at the level of 60%-65%, and the basicity of the high-basicity sintered ore is maintained at around 1.85. Reducing the basicity of the high-basicity sintered ore will have an adverse effect on the quality of the sintered ore, and the soft melting performance of the charge structure cannot be within the optimal range.

[0012] Affected by the low inventory strategy of mineral powder, there are few types of mineral powder resources, low inventory, and short batching cycle time, which is maintained at 3-5 days / time. For blast furnaces, fluctuations in the iron ore supply side of the batching side will lead to a chain reaction, affecting sintering output and component stability, and ultimately affecting the stability of blast furnace production. It is of great significance to study how to stabilize and improve the blast furnace charge structure under low inventory of mineral powder. Summary of the invention

[0013] The object of the present invention is to provide a method for stabilizing and improving the structure of blast furnace charge material, so as to solve the problems existing in the prior art.

[0014] The technical solution adopted by the present invention to solve its technical problem is:

[0015] A method for stabilizing and improving the structure of blast furnace charge material comprises the following steps:

[0016] (1) Determine the batching plan based on the mineral powder resources, the production capacity requirements of each sintering machine, the composition of the sintered ore, the blast furnace charge structure and the slag composition;

[0017] (2) Sintering is carried out according to the batching plan, and stable production is carried out according to the planned capacity requirements;

[0018] (3) The blast furnace is charged according to the planned charge structure. When CaO / SiO2 deviates from the target value, it is adjusted by adding high-silicon lump ore or silica.

[0019] Furthermore, in step (3), when the blast furnace is charged according to the planned charge structure, the proportion of high-basicity sintered ore, low-basicity sintered ore and lump ore is first stabilized. If the ideal slag system is not achieved and MgO / Al2O3 deviates from the target value, the sintering charge table is used for balance and adjustment is made by sintering MgO;

[0020] When the slag CaO / SiO2 deviates from the target value, it is balanced using the ironmaking ingredient list and adjusted by adding high-silicon lump ore or silica.

[0021] Furthermore, the composition of high silicon block ore is: total iron 52-57%, FeO3-7%, SiO214-18%, CaO≤0.04%, MgO≤0.1%, Al2O31.8-2.2%;

[0022] The silica composition is: SiO2≥98%, Al2O3≤2%.

[0023] Further, the addition amount of high silicon lump ore is: 1-3% of the mass of the charge structure;

[0024] The amount of silica added is: the mass of silica added to 1t of charge structure ≤5kg.

[0025] The present invention has the following beneficial effects:

[0026] 1. The present invention stabilizes the structure of the charge entering the furnace by consuming a small amount of silica or high-silicon lump ore at the end, achieves stability of the blast furnace slag system, stability of TiO2 entering the furnace, stability of the blast furnace condition, and decreases the blast furnace fuel consumption instead of increasing.

[0027] 2. By consuming a small amount of silica or high-silicon lump ore at the use end, the blast furnace charge structure is in the optimal range of soft melting performance, and the blast furnace condition is stable and smooth, which is conducive to the smooth consumption of economic materials and effectively promotes the achievement of Nippon Steel's low ore powder inventory strategy. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] A method for stabilizing and improving the structure of blast furnace charge material comprises the following steps:

[0030] (1) Determine the batching plan based on the mineral powder resources, the production capacity requirements of each sintering machine, the composition of the sintered ore, the blast furnace charge structure and the slag composition;

[0031] (2) Sintering is carried out according to the batching plan, and stable production is carried out according to the planned capacity requirements;

[0032] (3) The blast furnace is charged according to the planned charge structure. First, the proportion of high-basicity sintered ore, low-basicity sintered ore and lump ore is stabilized. If the ideal slag system is not achieved and MgO / Al2O3 deviates from the target value, the sintering charge table is used for balance and adjustment is made by sintering MgO; when the slag CaO / SiO2 deviates from the target value, it is adjusted by adding high-silicon lump ore or silica.

[0033] The composition of high silicon block ore is shown in Table 2:

[0034] Table 2: Composition of high silicon lump ore and silica stone

[0035] Total Iron FeO <![CDATA[SiO2]]> CaO MgO <![CDATA[Al2O3]]> High silicon lump ore 54.92 4.92 15.5 0.01 0.78 2.07 Silica 98.09 0.65

[0036] It can be seen from Table 2 that the SiO2 content of high-silicon lump ore and silica is high, and the silicon content of silica is at the level of 98%, which can mainly play the purpose of balancing the binary basicity (CaO / SiO2) of the slag.

[0037] The addition amount of high silicon lump ore is: 1-3% of the mass of the charge structure;

[0038] The amount of silica added is: the mass of silica added to 1t of charge structure ≤5kg.

[0039] From the perspective of cost optimization, high silicon block ore and silica are generally not as cost-effective as ordinary block ore. Increasing SiO2 requires additional CaO flux, and blast furnace slag making requires heat consumption, which will lead to increased fuel consumption. In the market, high silicon block ore is generally more cost-effective, so high silicon block ore is used first in adjustments. The proportion of high silicon block ore is at the level of 1-3%. When high silicon block ore resources are insufficient, silica is used, but the amount of silica used does not exceed 5kg / t. According to the ironmaking ingredient list, the consumption of high silicon block ore ratio of 2.5% and the use of silica of 5kg / t can achieve a high basicity sintered ore ratio and a low basicity sintered ore ratio of 4%, which can fully meet production needs.

[0040] In the case of low inventory, the consumption of silica or high silicon lump ore on the blast furnace side stabilizes and improves the charge structure, achieves the stability of the element load and slag composition, and improves the stable operation of the blast furnace. The following is a comparison of various indicators before and after the use of high silicon lump ore or silica.

[0041] 1) Comparison of charge structure:

[0042] Table 3: Changes in charge structure before and after using high silicon lump ore or silica stone

[0043] High basicity sintered ore Low basicity sinter Lump Ore Silica or high silicon lump ore No high silicon lumps or silica 65.8％ 24.5％ 9.7％ 0.0％ Use silica 69.2％ 20.4％ 10.4％ 3.0kg / t Use high silicon block ore 68.9％ 18.5％ 10.5％ 2.1％

[0044] After adding high silicon lump ore or silica, the proportion of high basicity sintered ore increased by about 3% and maintained at about 69%.

[0045] Table 4: Fluctuation of charge structure before and after using high silicon lump ore or silica stone

[0046]

[0047] It can be concluded from Tables 3 and 4 that after using high-silicon lump ore or silica, the fluctuation of charge structure is greatly reduced.

[0048] 2) Molten iron [Ti]:

[0049] Table 5: Changes in molten iron [Ti] content and molten iron [Ti] deviation

[0050] Hot metal [Ti] Molten Iron [Ti] Deviation No high silicon lumps or silica 0.096％ 0.028 Use high silicon lump ore or silica stone 0.074％ 0.010 contrast -0.022％ -0.018

[0051] It can be concluded from Table 5 that the use of high silicon lump ore or silica reduces the [Ti] deviation of molten iron by 0.018, a reduction of 64%.

[0052] 3) Slag MgO / Al2O3:

[0053] Table 6: Slag MgO / Al2O3 changes and slag MgO / Al2O3 deviation

[0054] <![CDATA[The MgO / Al2O3 of slag]]> <![CDATA[Deviation of slag MgO / Al2O3]]> No high silicon lumps or silica 0.748 0.041 Use high silicon lump ore or silica stone 0.758 0.014 contrast 0.010 -0.027

[0055] It can be concluded from Table 6 that the MgO / Al2O3 of the slag increases slightly after using high-silicon lump ore or silica, but the deviation decreases by 0.027, and the reduction rate reaches 66%.

[0056] 4) Benefit calculation:

[0057] Stability is the biggest cost reduction. By consuming appropriate silica or high-silicon lump ore from the user end, the basic consistency between plan and reality can be achieved. From the perspective of usage effect, a small amount of high-silicon lump ore or silica will reduce the blast furnace fuel consumption instead of increasing it.

[0058] Table 7: Changes in fuel ratio and furnace grade after using high silicon lump ore or silica stone

[0059] Fuel ratio Furnace Grade No high silicon lumps or silica 500.8 55.31％ Use high silicon lump ore or silica stone 498.3 54.95％ contrast -2.5 -0.36％

[0060] It can be concluded from Table 7 that after using high-silicon lump ore or silica, the grade entering the furnace decreased by 0.36%, and the fuel ratio decreased by 2.5 kg / t, and the fuel ratio decreased instead of increased.

[0061] The working principle of the present invention is:

[0062] The present invention focuses on the charge structure at the use end of the blast furnace. The charge structure of the blast furnace is composed of high-basicity sintered ore, low-basicity sintered ore and lump ore used in a planned proportion, matched with appropriate high-silicon lump ore or silica, and fully utilizing the high SiO2 content in the high-silicon lump ore and silica. When the high-basicity sintered ore, low-basicity sintered ore and lump ore are used in a planned proportion, by fine-tuning the usage of the high-silicon lump ore or silica, the blast furnace slag composition is stabilized, the charge structure is stabilized and improved, and the stable and smooth operation of the blast furnace is maintained.

[0063] The above embodiments are only for describing the preferred implementation of the present invention, and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made by ordinary persons in the art to the technical solution of the present invention should fall within the protection scope of the present invention.

[0064] The techniques, shapes, and structural parts not described in detail in the present invention are all well-known techniques.

Claims

1. A method for stabilizing and improving the structure of blast furnace charge, characterized in that: The following steps are involved: (1) Determine the batching plan based on the mineral powder resources, the production capacity requirements of each sintering machine, the composition of the sintered ore, the blast furnace charge structure and the slag composition; (2) Sintering is carried out according to the batching plan, and stable production is carried out according to the planned capacity requirements; (3) The blast furnace is charged according to the planned charge structure. When CaO / SiO2 deviates from the target value, it is adjusted by adding high-silicon lump ore or silica.

2. The method for stabilizing and improving the blast furnace charge structure according to claim 1, characterized in that: Step (3) When the blast furnace is charged according to the planned charge structure, the proportion of high-basicity sintered ore, low-basicity sintered ore and lump ore is first stabilized. If the ideal slag system is not achieved and MgO / Al2O3 deviates from the target value, the sintering charge table is used for balance and adjustment is made by sintering MgO; When the slag CaO / SiO2 deviates from the target value, it is balanced using the ironmaking ingredient list and adjusted by adding high-silicon lump ore or silica.

3. The method for stabilizing and improving the blast furnace charge structure according to claim 2, characterized in that: The high silicon block ore composition is: total iron 52-57%, FeO3-7%, SiO214-18%, CaO≤0.04%, MgO≤0.1%, Al2O31.8-2.2%; The silica composition is: SiO2≥98%, Al2O3≤2%.

4. The method for stabilizing and improving the blast furnace charge structure according to claim 3, characterized in that: The amount of high silicon lump ore added is: 1-3% of the mass of the charge structure; The amount of silica added is: the mass of silica added to 1t of charge structure ≤5kg.

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