A method for increasing the proportion of iron oxide scale in the sintering process

Abstract

This invention discloses a method for increasing the proportion of iron oxide scale in the sintering process, belonging to the field of iron oxide scale recycling technology. The method involves first pre-granulating at least a portion of the iron oxide scale with iron ore powder to obtain iron oxide scale pellets; then, the iron oxide scale pellets are further mixed and granulated with the remaining iron oxide scale and other sintering materials, and finally sintered. This invention, through pre-granulation, effectively solves the adverse effects of excessive iron oxide scale addition on the quality indicators of the sintered product, thus increasing the proportion of iron oxide scale added.

Description

Technical Field

[0001] This invention belongs to the field of iron oxide scale recycling technology, and more specifically, relates to a method for increasing the proportion of iron oxide scale in the sintering process. Background Technology

[0002] In steel enterprises, iron oxide scale mainly originates from the surface treatment of steel billets in hot rolling mills. During hot rolling, the reaction between steel and oxygen in the air often produces large amounts of iron oxide scale, causing accumulation and wasting resources. If these resources are utilized rationally, production costs can be reduced, while also contributing to energy conservation and environmental protection.

[0003] It should be noted that the sintering process in the metallurgical industry has a certain capacity for disposing of solid waste and possesses enormous potential for solid waste treatment. For example, Chinese patent application No. 201910502677.8 discloses a method for preparing sintered ore using rolled steel oxide scale and the prepared sintered ore. This application adds the iron oxide scale to the sintering mixture in a certain proportion for granulation, and finally puts it into the sintering machine for sintering, thereby effectively utilizing the rolled steel oxide scale and realizing the recycling of iron oxide scale.

[0004] For example, Chinese patent application No. 202111600239.9 discloses a method for preparing sintered ore by adding steel slag using a sintering process. The application specifies the following raw material proportions by mass percentage: 30%–70% Bayan Obo magnetite concentrate, 15%–60% iron ore powder A, 0%–10% iron ore powder B, 0%–3.0% steel slag tailings, 0%–2.0% iron oxide scale, 3.5%–5.5% limestone, 1.6%–3% dolomite, 0%–4.5% quicklime, 3.5%–5.5% coke powder, and 26%–32% blast furnace return ore. The raw materials are mixed with water and granulated to obtain a mixture. The mixture is then sintered to obtain sintered ore.

[0005] However, in existing technologies, iron oxide scale is usually mixed directly with other raw materials of sinter and then sintered. The utilization rate of iron oxide scale is relatively low and the amount of iron oxide scale added is small. When the amount of iron oxide scale added is large, it will lead to a significant decrease in the grade and quality indicators of sinter, which cannot meet the production requirements of blast furnace. Summary of the Invention

[0006] 1. The problem to be solved

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies, such as insufficient iron oxide scale addition in sintering materials and low utilization rate of iron oxide scale, and to provide a method for increasing the iron oxide scale ratio in the sintering process. This invention, through pre-granulation, effectively solves the adverse effects of excessive iron oxide scale addition on the quality indicators of sintered products, thus increasing the iron oxide scale addition ratio.

[0008] 2. Technical Solution

[0009] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0010] The present invention provides a method for improving the iron oxide scale ratio in the sintering process, which involves first pre-granulating at least a portion of the iron oxide scale with iron ore powder to obtain iron oxide scale balls; then, mixing and granulating the iron oxide scale balls with the remaining iron oxide scale and other sintering materials in a secondary process, and finally sintering.

[0011] Currently, existing technologies typically involve directly mixing iron oxide scale with other sintering materials. However, when a large amount of iron oxide scale is added, the mixing is poor, resulting in severe particle segregation. This affects the uniformity and permeability of the sintering layer, leading to uneven particle size in the sinter and consequently a significant decrease in sinter grade and overall quality. Therefore, in current technologies, the amount of iron oxide scale added to the sintering mixture is usually no more than 5%.

[0012] To address this issue, this application combines theoretical analysis with practical application, pre-granulating at least a portion of the iron oxide scale with iron ore powder before mixing and granulating it with other sintering materials. This effectively solves the aforementioned problem and achieves efficient utilization of the iron oxide scale. Specifically, in this application, the amount of iron oxide scale added is 10%-13% of the total sintering mixture, and the iron oxide scale participating in pre-granulation accounts for no less than 70% of the total mass of the iron oxide scale. That is, it can be added partially or entirely during the pre-granulation process.

[0013] The specific working principle of this application is as follows: The applicant discovered through research that iron oxide scale has excellent or relatively excellent assimilation and liquid-phase fluidity among commonly used iron ores. If iron oxide scale is directly added to the sintering raw materials for sintering, it easily causes overmelting in areas where iron oxide scale is enriched in the sintering mixture, ultimately resulting in uneven particle size distribution of the sinter. Therefore, this invention pre-granulates iron oxide scale with iron ore with weak assimilation properties. The physical mixing of raw materials with strong and weak assimilation properties effectively avoids the problem of localized overmelting or refractory materials caused by component segregation in the mixture, thereby improving the proportion of iron oxide scale in the sintering process.

[0014] Furthermore, the particle size of the iron oxide scale is less than or equal to 200 μm.

[0015] Furthermore, the iron ore powder comprises iron ore powder A and iron ore powder B, with the masses of iron ore powder A and iron ore powder B being 20%-35% and 24%-45% of the total sintering mixture, respectively.

[0016] Furthermore, the iron ore powder A contains the following components by mass percentage: TFe 64.0%-66.3%, FeO 24.5%-26.2%, SiO 23.0%-5.0%, Al 2O 31.5%-2.0%, MnO 0-0.2%, S 0-0.05%, P 0-0.02%, K 2O 0-0.07%; the iron ore powder B contains the following components by mass percentage: TFe 67.0%-69.2%, FeO 29.5%-31.3%, SiO 23.5%-1.7%, Al 2O 31.2%, MnO 0-0.2%, S 0-0.03%, P 0-0.15%.

[0017] Furthermore, during the pre-granulation process, iron oxide scale and iron ore powder are first mixed together for 15-20 minutes, and then pelletized on a disc pelletizer. The moisture content is controlled at 4.5-11%, and the particle size is controlled at 5-8 mm.

[0018] Furthermore, the iron oxide scale comprises the following components in weight percentage: TFe 66.0%-74.2%, FeO 46.5%-52.3%, SiO2 0.8%-2.0%, Al2O3 0.5%-1.5%, MnO 0-1.0%, S 0-0.06%, P 0-0.05%, and K2O 0-0.03%.

[0019] Furthermore, during secondary mixing and granulation, the following components by mass percentage are added: dust removal ash 1%-6%, internal return ore 9%-15%, external return ore 3%-10%, coke powder 2.5%-6.5%, quicklime 3%-6%, and dolomite 3.5%-7.0%.

[0020] Furthermore, during the secondary mixing and granulation process, the remaining iron oxide scale powder is first mixed with other sintering materials to prepare a sintering mixture. Then, the iron oxide scale pellets and the sintering mixture prepared in the first mixing stage are subjected to a secondary mixing and granulation. The final moisture content of the mixture is controlled at 7.3-7.6%. Excessive moisture content increases the number of large particles in the mixture, leading to excessive porosity in the sintered material layer, higher airflow velocity, and the loss of significant heat. Insufficient moisture content affects the granulation process, preventing the mixture from agglomerating into pellets of a certain size, resulting in poor permeability of the material layer and a severe decline in the quality indicators of the sintered ore.

[0021] Furthermore, the temperature of the sintering combustion zone is controlled at 1250-1350℃.

[0022] 3. Beneficial effects

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] (1) The present invention provides a method for improving the proportion of iron oxide scale in the sintering process. By pre-granulating iron oxide scale and iron ore powder to obtain iron oxide scale balls, the iron oxide scale balls are then mixed with other sintering materials and sintered together. This method can effectively overcome the adverse effects of adding too much iron oxide scale on the quality of sintered ore, significantly improve the proportion of iron oxide scale in the sintering process, and enable the iron oxide scale waste generated by steel enterprises to be utilized efficiently.

[0025] (2) The present invention provides a method for improving the iron oxide scale ratio in the sintering process. By optimizing the composition of iron oxide scale and iron ore powder and the particle size of iron oxide scale, it is beneficial to further improve the mixing uniformity of the sintering mixture, thereby improving the uniformity and permeability of the sintering material layer, and further ensuring the grade and quality indicators of sintered ore. Detailed Implementation

[0026] The present invention will be further described below with reference to specific embodiments.

[0027] Example 1

[0028] This embodiment provides a method for increasing the proportion of iron oxide scale during the sintering process, and the specific steps are as follows:

[0029] Step 1: Raw Material Preparation

[0030] (1) The raw materials are proportioned according to the following mass percentages: iron oxide scale: 12.0%, iron ore powder A: 35.0%, iron ore powder B: 24.3%, dust collector ash: 1.2%, internal return ore: 10.3%, external return ore: 5.3%, coke powder: 4.3%, quicklime: 4.0%, dolomite: 3.6%;

[0031] In this embodiment, the iron oxide scale is a solid waste generated during the steel rolling process of an iron and steel enterprise, and its composition by mass percentage is: TFe: 69.73%, FeO: 49.66%, SiO2: 1.38%, Al2O3: 1.11%, MnO: 0.72%, S: 0.035%, P: 0.02%, K2O: 0.01%; the iron ore powder A is a concentrate, and its composition by mass percentage is: TFe: 65.73%, FeO: 2%... The iron ore powder B is a type of iron ore powder, with the following composition by mass percentage: TFe: 67.74%, FeO: 30.88%, SiO2: 1.68%, Al2O3: 1.10%, MnO: 0.17%, S: 0.28%, P: 0.01%.

[0032] The dust collected in this embodiment has the following composition by mass percentage: TFe: 46.86%, FeO: 7.14%, SiO2: 6.84%, Al2O3: 2.66%, MnO: 0.17%, S: 3.41%, P: 0.07%, K2O: 5.10%; the internal return ore has the following composition by mass percentage: TFe: 56.98%, FeO: 9.74%. The composition of the external return ore is as follows: SiO2: 5.38%, Al2O3: 2.18%, MnO: 0.24%, S: 0.08%, P: 0.07%; the composition of the external return ore is as follows (mass percentage): TFe: 56.17%, FeO: 9.48%, SiO2: 5.76%, Al2O3: 2.03%, MnO: 0.27%, S: 0.10%, P: 0.07%.

[0033] The coke powder of this embodiment has the following composition by mass percentage: C: 83.95%, SiO2: 4.83%, Al2O3: 0.43%, CaO: 0.62%, MgO: 0.15%; the quicklime has the following composition by mass percentage: SiO2: 1.29%, Al2O3: 1.82%, CaO: 83.63%, MgO: 1.92%, P: 0.01%, S: 0.33%, and loss on ignition: 3.00%; the dolomite has the following composition by mass percentage: SiO2: 0.65%, Al2O3: 0.64%, CaO: 30.10%, MgO: 20.00%, P: 0.01%, S: 0.03%, and loss on ignition: 45.65%. However, it should be noted that this embodiment is only illustrated using the above-mentioned specific raw material composition as an example, but the specific composition of each raw material and the types of other sintering materials are not limited to this embodiment.

[0034] (2) All the iron oxide scale in the raw materials are crushed and ground to obtain iron oxide scale powder with a particle size ≤200 mesh.

[0035] Step 2: Pre-granulation of iron oxide scale

[0036] (1) Use a high-power mixer to mix 75% of the iron oxide scale powder with all the iron ore powder A and iron ore powder B in the raw materials evenly for 18 minutes;

[0037] (2) The above mixture is pelletized on a disc pelletizer while water is added to obtain iron oxide pellets with a moisture content of 7.4-8.0% and a particle size of 5-8 mm.

[0038] Step 3: Sintering and Granulation

[0039] (1) The remaining 25% of iron oxide powder, dust, internal return ore, external return ore, coke powder, quicklime and dolomite are mixed once in a high-pressure mixer. The mixture is mixed by spraying atomized water through a water sprayer after being pressurized by high-pressure nitrogen. The mixing time is 7 minutes. After mixing, a sintering mixture is prepared.

[0040] (2) Add the iron oxide pellets and the sintered mixture prepared by sintering to a cylindrical mixer for secondary mixing and granulation. The granulation time is 3 minutes. The final moisture content of the mixture is controlled at 7.3-7.6%. Then, the mixture is subjected to sintering experiment.

[0041] Step 4: Sintering the fabric

[0042] The final sintering mixture is then sintered to obtain sintered ore particles at a sintering temperature of 1300℃.

[0043] Sintering performance test:

[0044] To facilitate the testing of the quality of the obtained sinter, this embodiment places the mixture in a sintering cup for sintering experiments. The specific experimental procedure is as follows:

[0045] Step 1: First, add 2kg of bottom material to the grate of the sintering cup. Then, directly spread the well-mixed and granulated sintering material into the sintering cup, with a material layer height of 720mm. The amount of material loaded at one time is about 40kg.

[0046] Step 2: Sintering the fabric

[0047] The blower is started, and the intake and exhaust are controlled. Liquefied natural gas is used for ignition, with controlled air and fuel quantities. The ignition temperature is 1100℃, the ignition time is 90s, and the ignition negative pressure is 7kPa. Sintering timing begins at this point. After ignition, the negative pressure is adjusted to 14kPa for exhaust sintering. The exhaust gas temperature and exhaust negative pressure are automatically collected by a computer. Sintering ends when the exhaust gas temperature reaches its maximum and begins to decrease; the recorded time t is the complete sintering time. At the end of sintering, the exhaust pressure is adjusted to 7kPa. When the exhaust gas temperature cools to 300℃, the blower is turned off, and the sintered ore is poured out to obtain the finished sintered ore. The sintered ore is crushed by a crusher, then subjected to vibrating screen grading, drum strength testing, and other tests.

[0048] Step 3: Screening and Drum Testing

[0049] After sintering, the sintered ore is crushed and screened to obtain sintered ore of six different particle sizes. The mass of each of these six particle sizes is then measured. When measuring the drum strength of the sintered ore, according to the international standard ISO-3271-1975, a total of 7.5 kg of sintered ore of three particle sizes (25-40 mm, 16-25 mm, and 10-16 mm) is weighed according to the mass ratio and placed into the drum. The drum is started and rotated 200 revolutions. Then, the sintered ore is screened, with the vibrating screen swinging back and forth 20 times. The screened sintered ore is then removed, and the mass of each of the three particle sizes is weighed. The drum strength is obtained by dividing the weight of the sintered ore of the required particle size by the total mass of 7.5 kg.

[0050] Step 4: Metallurgical Performance Testing of Sintered Ore

[0051] (1) According to the national standard GB / T13242-91, the low-temperature reduction pulverization performance (RDI) of sintered ore was evaluated. +3.15 The test involved static reduction of samples with a particle size range (10-12.5 mm) in a fixed bed at 500°C using a reducing gas composed of CO, CO2, and N2. After 60 minutes of constant-temperature reduction, the samples were cooled, loaded into a rotating drum, rotated 300 rpm, and then removed. The samples were then graded using square-hole sieves of 6.3 mm, 3.15 mm, and 0.5 mm, and the content of each particle size was calculated. The final content was expressed as RDI. +3.15 The performance evaluation index for low-temperature reduction and pulverization of sintered ore.

[0052] (2) Refer to the national standard GB / T13241 to test the reduction performance (RI) of sintered ore. Place a sample with a certain particle size range (10-12.5mm) in a fixed bed and reduce it isothermally at 900℃ using a reducing gas composed of CO and N2. Weigh the sample at regular intervals and calculate the degree of reduction after 3 hours of reduction based on the trivalent iron state.

[0053] In this embodiment, after sintering, the quality indicators of the sintered product were measured, and the metallurgical properties of the sintered ore were measured. The experimental results are recorded in Table 1.

[0054] Comparative Example 1

[0055] This embodiment describes a method for increasing the proportion of iron oxide scale in the sintering process. The raw material ratio is the same as in Example 1, except that the iron oxide scale is not pre-granulated with iron ore powder A and iron ore powder B. Instead, the iron oxide scale is directly added to the sintering raw materials for mixing. After sintering, the sintering product quality indicators are measured, and the metallurgical properties of the sinter are measured. The experimental results are recorded in Table 1.

[0056] Comparative Example 2

[0057] This embodiment describes a method for increasing the proportion of iron oxide scale in the sintering process. The raw material ratio is the same as in Example 1, except that during the iron oxide scale pre-granulation process, 50% of the iron oxide scale powder is pre-granulated with iron ore A and iron ore powder B. After sintering, the quality indicators of the sintered product are measured, and the metallurgical properties of the sinter are measured. The experimental results are recorded in Table 1.

[0058] Example 2

[0059] This embodiment describes a method for increasing the proportion of iron oxide scale in the sintering process. The raw material proportion is the same as in Example 1, except that in step two, during the iron oxide scale pre-granulation process, all the iron oxide scale powder in the raw materials is pre-granulated with iron ore A and iron ore powder B. After sintering, the quality indicators of the sintered product are measured, and the metallurgical properties of the sintered ore are measured. The experimental results are recorded in Table 1.

[0060] Table 1. Sintering product quality indicators and metallurgical properties of sintered ore in different embodiments.

[0061]

[0062] Analysis of the indicators in Table 1 leads to the following conclusions:

[0063] Compared with Example 1, Comparative Example 1 did not involve pre-granulation of iron oxide scale with iron ore powder A and iron ore powder B. This resulted in a 2.04 mm / min decrease in sintering speed, a 6.96% decrease in yield, a 0.56% decrease in utilization coefficient, an 11.61% decrease in drum index, a 5.87 kg / t increase in fuel consumption, a 4.43% decrease in RI, and a decrease in RDI. +3.15 It decreased by 1.67%;

[0064] Compared with Example 1, Comparative Example 2, using 50% iron oxide scale with iron ore powder A and iron ore powder B for pre-granulation, resulted in a sintering speed reduction of 1.25 mm / min, a yield reduction of 4.97%, a utilization coefficient reduction of 0.34%, a drum index reduction of 2.66%, an increase in fuel consumption of 8.24 kg / t, a decrease in RI of 1.67%, and a decrease in RDI. +3.15 It decreased by 1.49%;

[0065] Compared with Example 1, Example 2 involved pre-granulating all the iron oxide scale with iron ore powder A and iron ore powder B. This resulted in a sintering speed reduction of 0.56 mm / min, a yield increase of 11.26%, a utilization coefficient reduction of 0.01%, a drum index reduction of 6.93%, a fuel consumption reduction of 8.80 kg / t, a RI reduction of 1.63%, and an RDI reduction of [missing information]. +3.15 It decreased by 1.94%.

[0066] Therefore, pre-granulating at least a portion of the iron oxide scale with iron ore powder, and then mixing and granulating it with other sintering materials, while optimizing and controlling the amount of iron oxide scale added in the pre-granulation process, can help reduce the adverse effects of excessive iron oxide scale addition on the quality of sintered ore, thereby significantly increasing the amount of iron oxide scale added.

[0067] Example 3

[0068] This embodiment provides a method for increasing the proportion of iron oxide scale during the sintering process, and the specific steps are as follows:

[0069] Step 1: Raw Material Preparation

[0070] (1) The raw materials are proportioned according to the following mass percentages: iron oxide scale: 10.0%, iron ore powder A: 30.0%, iron ore powder B: 30%, dust collector ash: 3%, internal return ore: 15%, external return ore: 3%, coke powder: 2.5%, quicklime: 3.0%, dolomite: 3.5%;

[0071] In this embodiment, the iron oxide scale is a solid waste generated during the steel rolling process of an iron and steel enterprise, and its composition by mass percentage is: TFe: 66%, FeO: 46.5%, SiO2: 0.8%, Al2O3: 1.5%, MnO: 1.0%, S: 0.02%, P: 0.01%, K2O: 0.03%; the iron ore powder A is a concentrate, and its composition by mass percentage is: TFe: 64%, FeO: The iron ore powder B is a type of iron ore powder, with the following composition by mass percentage: TFe: 69%, FeO: 29.5%, SiO2: 1.5%, Al2O3: 0.9%, Al2O3: 0.9%, MnO: 0.12%, S: 0.2%, P: 0.05%.

[0072] The composition of dust, internal return ore, external return ore, coke powder, quicklime, and dolomite in this embodiment is the same as that in Embodiment 1, but other components can also be selected, and it is not limited to the specific composition of Embodiment 1.

[0073] (2) All the iron oxide scale in the raw materials are crushed and ground to obtain iron oxide scale powder with a particle size ≤200 mesh.

[0074] Step 2: Pre-granulation of iron oxide scale

[0075] (1) Use a high-powered mixer to mix 70% of the iron oxide scale powder with all the iron ore powder A and iron ore powder B in the raw materials evenly for 15 minutes;

[0076] (2) The above mixture is pelletized on a disc pelletizer while water is added to obtain iron oxide pellets with a moisture content of 7.4-8.0% and a particle size of 5-8 mm.

[0077] Step 3: Sintering and Granulation

[0078] (1) The remaining 30% of iron oxide powder, dust, internal return ore, external return ore, coke powder, quicklime and dolomite are mixed once in a high-pressure mixer. The mixture is mixed by spraying atomized water through a water sprayer after being pressurized by high-pressure nitrogen. The mixing time is 8 minutes. After mixing, a sintering mixture is prepared.

[0079] (2) Add the iron oxide pellets and the sintered mixture prepared by sintering to a cylindrical mixer for secondary mixing and granulation. The granulation time is 4 min. The final moisture content of the mixture is controlled at 7.3-7.6%. Then, the mixture is subjected to sintering experiment.

[0080] Step 4: Sintering the fabric

[0081] The final sintering mixture is then sintered to obtain sintered ore particles at a sintering temperature of 1250℃.

[0082] Example 4

[0083] This embodiment provides a method for increasing the proportion of iron oxide scale during the sintering process, and the specific steps are as follows:

[0084] Step 1: Raw Material Preparation

[0085] (1) The raw materials are proportioned according to the following mass percentages: iron oxide scale: 13.0%, iron ore powder A: 20.0%, iron ore powder B: 26.5%, dust collector ash: 6%, internal return ore: 9%, external return ore: 6%, coke powder: 6.5%, quicklime: 6.0%, dolomite: 7.0%;

[0086] In this embodiment, the iron oxide scale is a solid waste generated during the steel rolling process of an iron and steel enterprise, and its composition by mass percentage is: TFe: 74.1%, FeO: 52.3%, SiO2: 2.0%, Al2O3: 0.5%, S: 0.06%, P: 0.05%; the iron ore powder A is a concentrate, and its composition by mass percentage is: TFe: 65.73%, FeO: 25.02%, SiO2: 4%. The iron ore powder B is a type of iron ore powder, with the following composition by mass percentage: TFe: 67.74%, FeO: 30.88%, SiO2: 1.68%, Al2O3: 1.10%, MnO: 0.17%, S: 0.28%, P: 0.01%. The composition of the dust collector ash, internal return ore, external return ore, coke powder, quicklime, and dolomite in this embodiment is the same as in Example 1, but other components can also be used, and it is not limited to the specific composition of Example 1.

[0087] (2) All the iron oxide scale in the raw materials are crushed and ground to obtain iron oxide scale powder with a particle size ≤200 mesh.

[0088] Step 2: Pre-granulation of iron oxide scale

[0089] (1) Use a high-powered mixer to mix 80% of the iron oxide scale powder with all the iron ore powder A and iron ore powder B in the raw materials evenly for 20 minutes;

[0090] (2) The above mixture is pelletized on a disc pelletizer while water is added to obtain iron oxide pellets with a moisture content of 7.4-8.0% and a particle size of 5-8 mm.

[0091] Step 3: Sintering and Granulation

[0092] (1) The remaining 20% ​​of iron oxide powder, dust, internal return ore, external return ore, coke powder, quicklime and dolomite are mixed once in a high-pressure mixer. The mixture is mixed by spraying atomized water through a water sprayer after being pressurized by high-pressure nitrogen. The mixing time is 5 minutes. After mixing, a sintering mixture is prepared.

[0093] (2) Add the iron oxide pellets and the sintered mixture prepared by sintering to a cylindrical mixer for secondary mixing and granulation. The granulation time is 6 minutes. The final moisture content of the mixture is controlled at 7.3-7.6%. Then, the mixture is subjected to sintering experiment.

[0094] Step 4: Sintering the fabric

[0095] The final sintering mixture is then sintered to obtain sintered ore particles at a sintering temperature of 1350℃.

[0096] Example 5

[0097] This embodiment provides a method for increasing the proportion of iron oxide scale during the sintering process, and the specific steps are as follows:

[0098] Step 1: Raw Material Preparation

[0099] (1) The raw materials were prepared according to the following mass percentages: iron oxide scale: 11.0%, iron ore powder A: 20.0%, iron ore powder B: 45%, dust collector ash: 2%, internal return ore: 9%, external return ore: 3%, coke powder: 3%, quicklime: 3%, dolomite: 4%; The composition of iron oxide scale, iron ore powder A, iron ore powder B, dust collector ash, internal return ore, external return ore, coke powder, quicklime and dolomite in this embodiment is the same as in Example 1.

[0100] (2) All the iron oxide scale in the raw materials are crushed and ground to obtain iron oxide scale powder with a particle size ≤200 mesh.

[0101] Step 2: Pre-granulation of iron oxide scale

[0102] (1) Use a high-power mixer to mix 73% of the iron oxide scale powder with all the iron ore powder A and iron ore powder B in the raw materials evenly for 16 minutes;

[0103] (2) The above mixture is pelletized on a disc pelletizer while water is added to obtain iron oxide pellets with a moisture content of 7.4-8.0% and a particle size of 5-8 mm.

[0104] Step 3: Sintering and Granulation

[0105] (1) The remaining 27% of iron oxide powder, dust, internal return ore, external return ore, coke powder, quicklime and dolomite are mixed once in a high-pressure mixer. The mixture is mixed by spraying atomized water through a water sprayer after being pressurized by high-pressure nitrogen. The mixing time is 5 minutes. After mixing, a sintering mixture is prepared.

[0106] (2) Add the iron oxide pellets and the sintered mixture prepared by sintering to a cylindrical mixer for secondary mixing and granulation. The granulation time is 4 min. The final moisture content of the mixture is controlled at 7.3-7.6%. Then, the mixture is subjected to sintering experiment.

[0107] Step 4: Sintering the fabric

[0108] The final sintering mixture is then sintered to obtain sintered ore particles at a sintering temperature of 1280℃.

Claims

1. A method for improving the proportioning of iron oxide scale in a sintering process, characterized by: First, at least part of the oxide scale is pregranulated together with the iron ore powder to obtain oxide scale pellets; then the oxide scale pellets are mixed and granulated again with the remaining oxide scale and other sintering materials, and finally sintering is carried out; the addition amount of the oxide scale is 10%-13% of the total amount of the sintering mixture, and the mass percentage of the oxide scale participating in the pregranulation is not less than 70% of the total amount of the oxide scale; The iron ore powder comprises iron ore powder A and iron ore powder B, and the mass of the iron ore powder A and the iron ore powder B is 20%-35% and 24%-45% of the total amount of the sintering mixture, respectively; The iron ore powder A comprises the following components with the mass percentage: TFe 64.0%-66.3%, FeO 24.5%-26.2%, SiO2 3.0%-5.0%, Al2O3 1.5%-2.0%, MnO 0-0.2%, S 0-0.05%, P 0-0.02%, and K2O 0-0.07%; the iron ore powder B comprises the following components with the mass percentage: TFe 67.0%-69.2%, FeO 29.5%-31.3%, SiO2 1.5%-1.7%, Al2O3 0.9%-1.2%, MnO 0-0.2%, S 0-0.03%, and P 0-0.15%; The oxide scale comprises the following components with the mass percentage: TFe 66.0%-74.2%, FeO 46.5%-52.3%, SiO2 0.8%-2.0%, Al2O3 0.5%-1.5%, MnO 0-1.0%, S 0-0.06%, P 0-0.05%, and K2O 0-0.03%.

2. The method for improving the ratio of iron oxide scale in the sintering process according to claim 1, characterized in that: The particle size of the oxide scale is less than or equal to 200 μm.

3. The method for improving the ratio of iron oxide scale in the sintering process according to claim 1 or 2, characterized in that, In the pregranulation process, the oxide scale is first mixed with the iron ore powder for 15-20 min, and then balling and granulation are carried out on a disc balling machine, the water content is controlled to be 4.5-11%, and the granulation particle size is controlled to be 5-8 mm.

4. The method for improving the ratio of iron oxide scale in the sintering process according to claim 1 or 2, characterized in that, In the secondary mixing and granulation, the following components are added with the mass percentage: dust 1%-6%, internal return fines 9%-15%, external return fines 3%-10%, coke powder 2.5%-6.5%, quicklime 3%-6%, and dolomite 3.5%-7.0%.

5. The method of improving the ratio of iron oxide scale in the sintering process according to claim 4, characterized in that, In the secondary mixing and granulation, the remaining oxide scale powder is first mixed with other sintering materials to prepare a sintering mixture; then the oxide scale pellets and the sintering mixture prepared by the first mixing are mixed and granulated, and the final water content of the mixture is controlled to be 7.3-7.6%.

6. The method for improving the ratio of iron oxide scale in the sintering process according to claim 1 or 2, characterized in that, The sintering combustion zone temperature is controlled to be 1250-1350℃.

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