A method for improving calcium ferrite formation by sintering flux segregation

Abstract

The application belongs to the technical field of sintering, and discloses a method for improving calcium ferrite generation by sintering flux segregation, which comprises the following steps: S1, determining a sintering ore blending scheme, and determining the type of iron ore powder for sintering; S2, testing the calcium ferrite generation capacity of different types of iron ore powder, and ranking the calcium ferrite generation capacity according to the advantages and disadvantages, and preferably selecting one or more types of iron ore powder with better calcium ferrite generation capacity; S3, mixing the preferred iron ore powder determined in step S2 with a predetermined flux, and then adding the mixture into a sintering mixer together with the remaining iron ore powder and fuel, and then mixing with water to form granules, and then feeding the granules into a sintering machine for sintering. By the method, the sintering flux is uniformly distributed on the whole and is segregated and distributed around the high-quality iron ore powder in the micro aspect, so that the sintering flux is more conducive to the generation of high-quality calcium ferrite in the sintering process, the utilization rate of the sintering flux is improved, and the reaction of the poor-quality iron ore is not affected.

Description

Technical Field

[0001] This invention belongs to the field of sintering technology, and particularly relates to a method for improving the formation of calcium ferrite through sintering flux segregation. Background Technology

[0002] In recent years, with the advancement of blast furnace ironmaking technology, the increasing size of blast furnaces, and the intensification of smelting processes, the requirements for sinter quality have become increasingly stringent. Currently, sinter blending is largely based on experience, retaining the proportion of iron ore powders considered to have good sintering performance and making minor adjustments to the proportion of newly added iron ore powders. At the same time, due to the scarcity of iron ore resources, the types of iron ore used for sintering are increasing and becoming more complex.

[0003] Traditional sintering involves mixing various sintering raw materials together in a mixer, resulting in a relatively uniform mixture. However, this excessive uniformity prevents the sintering flux from functioning effectively. Due to the limited flux quantity, low-quality iron ore requires the same proportion of flux as high-quality iron ore. This leads to a lack of or insufficient flux particles around iron ore powder particles with strong calcium ferrite formation capabilities, thus inhibiting the formation of high-quality calcium ferrite. Summary of the Invention

[0004] The purpose of this invention is to address the current problems in sintering ore blending and improve the formation of high-quality calcium ferrite in sintering. This invention provides a method to improve calcium ferrite formation through flux segregation in sintering. The invention proposes to select iron ore powder with strong calcium ferrite-forming ability, pre-mix it with flux, and then mix it with the remaining sintering materials for granulation and sintering. This achieves the effect of ensuring that the flux is uniformly distributed overall while also being microscopically segregated and distributed around the high-quality iron ore powder.

[0005] The technical problem to be solved by this invention is achieved by the following technical solution: a method for improving the formation of calcium ferrite through sintering flux segregation, comprising the following steps:

[0006] S1. Pre-determine the sintering ore blending scheme, that is, determine the type of iron ore powder to be used for sintering according to the designed sintering ore blending scheme;

[0007] S2. Test the calcium ferrite formation ability of different iron ore powders, rank them according to their calcium ferrite formation ability, and select one or more iron ore powders with better calcium ferrite formation ability.

[0008] S3. The preferred iron ore powder determined in step S2 is mixed with the predetermined flux, and then added to the sintering mixing machine along with the remaining iron ore powder and fuel. Water is added for granulation, and the mixture is then sintered.

[0009] According to a preferred embodiment of the present invention, the specific method for testing the calcium ferrite formation capacity in step S2 is as follows:

[0010] The required flux dosage and the mass ratio of total ore powder are obtained according to the sintering blending scheme. The flux and individual ores are mixed and crushed according to the above ratio, then briquetted for micro-sintering tests. After the test, the calcium ferrite content in the sintered product is measured. Previously, calcium ferrite formation capacity was analyzed by determining the basicity. However, the mixed particles are still independent entities. At the micro-unit level, different ores have different basicities, and the basicity will naturally differ even with the same flux. This invention uses a fixed mass ratio method to test the calcium ferrite formation capacity of iron ore powder. Using a fixed mass ratio rather than a fixed basicity method for calcium ferrite formation tests is more consistent with actual sintering and more realistic. Specifically, existing technologies for testing the calcium ferrite formation capacity of iron ore generally use a fixed basicity CaO / SiO2 method, judging the amount of calcium ferrite formed at a certain temperature and basicity. However, the actual material layer particles still exist independently, and the CaO and SiO2 contents vary among different materials. Obviously, materials with lower basicity require more flux in the batching. Since the contact opportunities between raw material particles and flux are equal in the actual material layer, the results obtained using existing technology do not match the actual batching situation. The solution of this invention, however, is to optimize the iron ore with strong calcium ferrite formation capacity based on the actual batching ratio, allowing it more opportunities to contact the flux and reducing the flux consumption of ores with poor calcium ferrite formation capacity in the batching, thus better matching the actual situation.

[0011] According to a preferred embodiment of the present invention, the particle size of the flux after being mixed and crushed with a single ore is less than 100 mesh.

[0012] According to a preferred embodiment of the present invention, in step S2, the preferred proportion of iron ore powder by weight is at least 5% of the total iron ore powder. To ensure effective mixing and to guarantee an effective increase in the production of calcium ferrite, the preferred proportion of iron ore powder by weight is at least 5% of the total iron ore powder.

[0013] According to a preferred embodiment of the present invention, in step S2, the weight of the preferred iron ore powder with superior calcium ferrite generating capacity accounts for 5-20% of the total iron ore powder. Considering the production rhythm and mixing effect, the weight of the preferred iron ore powder with superior calcium ferrite generating capacity is set at 5-20% of the total iron ore powder to improve the ore blending efficiency.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] This invention, based on existing processes, prioritizes the selection of iron ore powder with strong calcium ferrite-forming ability and pre-mixes it with flux. This enhances the bonding between the high-quality iron ore powder and the flux, promoting the formation of calcium ferrite during sintering. This achieves uniform mixing of the main components during sintering while simultaneously promoting flux segregation around the high-quality iron ore powder. Consequently, the sintering flux is more conducive to the formation of high-quality calcium ferrite during sintering, improving flux utilization without affecting the reaction of inferior iron ore. Attached Figure Description

[0016] Figure 1 This is a process flow diagram of an embodiment of the present invention;

[0017] Figure 2 This diagram illustrates that the flux R in the sintering mixture of the existing ore blending method has an equal opportunity to contact with each ore type A, B, C, D, and E.

[0018] Figure 3 This is a schematic diagram illustrating how high-quality iron ore A is more easily contacted with flux particles R in an embodiment of the present invention. Detailed Implementation

[0019] The present invention will be further described below with reference to embodiments.

[0020] A method for improving calcium ferrite formation by flux segregation during sintering includes the following steps:

[0021] S1. Based on the sintering ore blending scheme, determine the type of iron ore powder used for sintering and its mass percentage in the total iron ore powder. The sintering ore blending scheme also specifies the type and mass percentage of other materials such as flux and fuel, as well as the amount of water to be added. These are set according to the specific sintering ore blending scheme and are not specifically limited here.

[0022] S2. The calcium ferrite formation capacity of different iron ore powders was tested. The test adopted the fixed mass ratio method. According to the ore mixing scheme, a certain mass of iron ore powder and flux were weighed separately according to the mass ratio of flux to total iron ore powder. The mixture was crushed to less than 100 mesh, mixed evenly to form a homogeneous material, and then pressed into briquettes and placed in a micro sintering device for sintering. The calcium ferrite content of the sintered ore phase was detected and ranked, and the iron ore powder with strong calcium ferrite formation capacity was selected.

[0023] S3. During sintering production, one or more preferred iron ore powders with strong calcium ferrite generating capacity are separated out, preferably accounting for 5-20% of the total iron ore powder by weight, and are premixed with flux in advance to form a mixture.

[0024] The mixture obtained above is then added to the sintering machine along with the remaining iron ore powder and fuel for sintering, mixed with water, granulated, and then sintered.

[0025] Five types of iron ore powder A, B, C, D, and E ( Figure 1 (Not fully shown in the text), taking flux R as an example, using existing ore blending methods, such as... Figure 2 As shown, the flux R in the sintering mixture has an equal chance of contact with each mineral A, B, C, D, and E, and each mineral has the same chance of reacting with flux R. This means that the flux R cannot play its maximum role, which affects the formation of calcium ferrite.

[0026] According to the method of the present invention, iron ore powder A has the strongest calcium ferrite forming ability, such as Figure 1As shown, iron ore powder A is first mixed with flux R, and then mixed with four other types of iron ore powders (B, C, D, and E) and fuel, as follows: Figure 3 As shown, high-quality iron ore A is more likely to come into contact with flux R particles, thereby allowing more flux R to react with iron ore powder A to generate more calcium ferrite, while not affecting the reaction of flux R with other minerals such as B, C, D, and E.

[0027] To further demonstrate the technical effectiveness of the method of the present invention, specific embodiments are described below.

[0028] Example 1

[0029] The method of this invention was used to test the calcium ferrite formation capacity of 10 iron ore types in the sintering batching scheme of a steel plant. The proportions of the ore types in the sintering batching scheme are shown in Table 1. The mass ratio of flux quicklime to ore types is 15.3%. The flux and individual iron ore powders were weighed and crushed according to the proportion, mixed, and then placed in a micro sintering test device for testing. The calcium ferrite content in the sinter was determined. The results of the micro sintering experiments with each ore type and flux mixed according to the mass ratio are shown in Table 1.

[0030] Table 1

[0031]

[0032] Based on the results of the micro-sintering experiments, it can be seen that ore 4 has the best calcium ferrite formation capacity, accounting for 18% of the iron-containing material. In production, this material is used to pre-mix with flux, and then mixed with the remaining raw materials for sintering through the first and second mixing processes, followed by sintering according to the normal sintering regime. The comparison between the resulting sintered mineral structure and the normal sintered mineral structure is shown in Table 2. Normal sintering involves direct mixing and blending of minerals using existing ore blending methods.

[0033] Table 2

[0034]

[0035] As can be seen from the data in Table 2, after applying the method of the present invention, the calcium ferrite content in the sintered ore phase increased from the original 24.47% to 36.86%, an increase of 12.39%.

[0036] Example 2

[0037] Based on Example 1, the premixing ratio of high-quality ore 4 was reduced. In production, half of this material was used to premix with flux, and then mixed with the remaining raw materials for sintering through sintering mixing and granulation. Finally, sintering was carried out according to the normal sintering process. The resulting sintered mineral structure is compared with that of normally sintered minerals in Table 3.

[0038] Table 3

[0039]

[0040] As can be seen from the data in Table 3, although the premixing ratio of high-quality iron ore 4 was reduced after using the method of the present invention, the calcium ferrite in the sinter phase still increased from the original 24.47% to 33.03%, an increase of 8.56%.

[0041] Example 3

[0042] According to the sintering calcium ferrite production capacity test in Example 1, the mass ratio of flux to iron ore powder is still 15.3%. The proportion of each mineral is adjusted, and the proportion of ore 4 is reduced. The mineral ratios in the sintering batching scheme are shown in Table 4.

[0043] Table 4

[0044]

[0045]

[0046] In production, all of ore 4 is used for premixing with flux, then mixed with the remaining raw materials in the sintering process through sintering I and II, and granulated, followed by sintering according to the normal sintering regime. The resulting sintered mineral structure is compared with that of normally sintered minerals in Table 5.

[0047] Table 5

[0048]

[0049] As can be seen from the data in Table 5, after applying the invention, although the proportion of high-quality iron ore premixed is relatively small, the calcium ferrite in the sinter phase in the examples still increased from the original 25.13% to 32.66%, an increase of 7.53%.

Claims

1. A method for improving calcium ferrite formation through flux segregation during sintering, characterized in that, Includes the following steps: S1. Determine the sintering ore blending scheme and the type of iron ore powder to be used for sintering; S2. Test the calcium ferrite formation ability of different iron ore powders, rank them according to their calcium ferrite formation ability, and select one or more iron ore powders with better calcium ferrite formation ability. In step S2, the specific method for testing the calcium ferrite formation capacity is as follows: Obtain the required flux dosage and the mass ratio of total ore powder in the ore blending scheme. Mix the flux with a single ore in the above ratio, crush the mixture, and then press it into briquettes for micro sintering tests. After the test, determine the calcium ferrite content in the sintered product. The preferred iron ore powder with superior calcium ferrite formation capacity accounts for at least 5% of the total iron ore powder by weight; S3. Mix the preferred iron ore powder determined in step S2 with the predetermined flux to obtain a premix; The premixed material is mixed with the remaining iron ore powder and fuel, then granulated with water and sintered in a sintering machine.

2. The method for improving calcium ferrite formation by flux segregation during sintering according to claim 1, characterized in that: The particle size after the flux is mixed and crushed with a single ore is less than 100 mesh.

3. The method for improving calcium ferrite formation by flux segregation during sintering according to claim 1, characterized in that: In step S2, the weight of the preferred iron ore powder with superior calcium ferrite formation capacity accounts for 5-20% of the total iron ore powder.

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