Sintering mixture and preparation method thereof

Abstract

The invention relates to the technical field of sintered ore production, in particular to a sintering mixture and a preparation method thereof.According to the method, a large proportion of iron-containing dust sludge is adopted as a raw material to prepare the sintering mixture, and the sintering mixture comprises mixed iron-containing dust sludge, iron ore concentrate, fine ore, coke powder, magnesite powder and slaked lime powder; the mixed type iron-containing dust mud comprises blast furnace gas mud, converter mud and sintering machine tail dedusting ash, and the weight percentage content of the blast furnace gas mud, the converter mud and the sintering machine tail dedusting ash is 20%-25%: 8%-15%: 65%-70%. The method has the beneficial effects that the problems that the sintering mixture is poor in strength and unreasonable in particle size composition due to the fact that the iron-containing dust mud is directly used as the raw material for preparing the sintering mixture, and the yield and quality of sintered ore are deteriorated are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of sinter production, and particularly relates to a sinter mixture and a preparation method thereof. Background Art

[0002] There are many types of mineral resources in China. Its general characteristics are: poor, fine, miscellaneous, few rich ore resources, many associated lean ores, and few easy-to-dress ores. Therefore, in recent years, the steel industry in China has a relatively high dependence on imported iron ore. In 2023, China imported 1,179,060,000 tons of iron ore in total. The large demand for iron ore has led to a shortage in the iron ore market, resulting in consecutive price increases of imported ore and continuous climbing of enterprise production costs, which has brought a great impact on the stable and rapid development of the steel industry. Facing this situation, the comprehensive utilization of secondary resources has become a countermeasure that the metallurgical industry must consider and study for the development of circular economy.

[0003] During the production process, iron and steel enterprises emit a large amount of iron-containing dust and sludge, such as sintering dust, blast furnace gas ash, tapping yard dust, steelmaking red dust, converter sludge, gas sludge, etc. Since they contain utilizable components such as iron, carbon, CaO, and MgO, we collectively refer to them as secondary resources. In this part of the resources, the iron content is relatively high and has good utilization value. If not utilized, it will not only waste resources but also cause serious environmental pollution.

[0004] Another problem brought about by the rapid development of the steel industry is the emission of a large amount of iron-containing dust and sludge. According to statistics, the generation amount of iron-containing dust and sludge in large steel enterprises in China accounts for about 10% of their steel production. Among them, the generation amount of solid waste in the rolling process accounts for about 0.8 - 1.5% of the rolled product output, the generation amount of dust and sludge in the steelmaking process accounts for about 3 - 4% of the steel output, the generation amount of dust (sludge) in the ironmaking process accounts for about 3 - 4% of the hot metal output, and the generation amount of dust in the sintering process accounts for about 2 - 4% of the sinter output. Calculated according to this ratio, the annual emission of iron-containing dust and sludge in China is very large. These iron-containing dust and sludge not only contain recyclable iron elements but also contain some useful substances such as C, CaO, and MgO. However, due to the characteristics of fine and irregular particle size, poor hydrophilicity, and difficulty in pelletizing of iron-containing dust and sludge, directly using it as a raw material to prepare sinter mixture leads to poor strength of the sinter mixture and unreasonable particle size composition, thus deteriorating the output and weight of sinter. The comprehensive secondary utilization is mostly limited utilization, and most of the iron-containing slag dust is long-term abandoned and stacked.

[0005] On the one hand, domestic mineral resources are severely scarce, necessitating large quantities of iron ore imports. On the other hand, large quantities of iron-containing dust and sludge from steel mills remain unused, lost, and wasted. Therefore, effectively utilizing these "waste" resources has become a pressing issue for steel companies. Failure to utilize them not only wastes resources but also poses a significant risk of serious environmental pollution. Especially in the context of scarce iron ore resources and increasing pressure on environmental governance, fully utilizing iron-containing resources such as metallurgical slag and dust and sludge waste can alleviate both resource constraints and environmental challenges in steel production, contributing to the healthy development of the steel industry. Summary of the Invention

[0006] In order to overcome the deficiencies of the prior art, the present invention provides a sintering mixture and a preparation method thereof, which achieves the purpose of using iron-containing dust mud as a raw material to prepare the sintering mixture in a relatively large proportion, overcomes the problem that the sintering mixture has poor strength and unreasonable particle size composition when directly using the iron-containing dust mud as a raw material to prepare the sintering mixture due to the characteristics of fine and irregular particle size, poor hydrophilicity and difficulty in balling, thereby worsening the output and weight of the sintered ore. The present invention broadens the raw material usage conditions for sintered ore production, makes full use of the iron-containing dust mud as a secondary resource, and reduces the production cost of the sintered ore.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A sintering mixture comprises mixed iron-containing dust, iron concentrate, fine ore, coke powder, magnesite powder and slaked lime powder. The mixed iron-containing dust comprises blast furnace gas mud, converter mud and sintering machine tail dust ash, which are fully mixed according to the weight percentage of 20% to 25%, 8% to 15% and 65% to 70% respectively to obtain the mixed iron-containing dust.

[0009] Furthermore, the chemical composition of the mixed iron-containing dust mud is as follows in percentage by weight: TFe: 55% to 60%, CaO: 5% to 10%, MgO: 2% to 5%, SiO2: 1% to 7%, Al2O3: 0.5% to 3%, and the remainder is impurity elements.

[0010] Furthermore, the chemical composition of the iron ore by weight is as follows: TFe: 67% to 70%, FeO: 9% to 31%, CaO: 0.05% to 0.3%, MgO: 0.1% to 0.5%, SiO2: 3% to 6%, Al2O3: 0.1% to 0.3%, and the remainder is impurity elements; the chemical composition of the powder ore by weight is as follows: TFe: 50% to 66%, FeO: 0.2% to 2%, CaO: 0.1% to 0.5%, MgO: 0.1% to 0.5%, SiO2: 3% to 7%, Al2O3 : 1.5% to 7%, the balance being impurities; the industrial composition weight percentage of the coke powder is: fixed carbon 80% to 86%, ash 11% to 14%, volatile matter 1% to 4%, moisture 0.5% to 3%, and the rest being impurities; the chemical composition weight percentage of the magnesite powder is: CaO: 2% to 5%, MgO: 42% to 45%, SiO2: 10% to 13%, Al2O3: 0.5% to 2%, and the balance being impurities; the slaked lime powder is a high specific surface area slaked lime with a specific surface area of 300,000 to 400,000 cm 2 / g.

[0011] Furthermore, the preparation method comprises the following steps:

[0012] (1) The blast furnace gas mud, converter mud and sintering machine tail dust in the iron-containing dust mud are dried and crushed respectively to remove the lumps formed by them. The particle size after crushing is less than 0.074mm.

[0013] (2) finely grinding the coke powder, magnesite powder and slaked lime powder used in sintering production respectively, wherein the particle size after fine grinding is less than 0.05 mm, thereby obtaining finely ground coke powder, finely ground magnesite powder and finely ground slaked lime powder.

[0014] (3) The iron ore concentrate, fine ore, and mixed iron-containing dust are mixed in a weight percentage ratio of 15% to 55%, 35% to 70%, and 10% to 15%, and limestone powder, magnesite powder, and coke powder are added in an external form to obtain a mixture A.

[0015] (4) The mixed iron-containing dust mud, finely ground coke powder, finely ground magnesite powder, and finely ground slaked lime powder are fully mixed in a powerful mixer according to the weight percentage of 85% to 90%: 2% to 6%: 2% to 5%: 2% to 6%, respectively, so that the mixed iron-containing dust mud particles are fully in contact with the coke powder, magnesite, and slaked lime particles to obtain pretreated mixed iron-containing dust mud.

[0016] (5) The pretreated mixed iron-containing dust mud is transported to a disc pelletizing machine for pelletizing. During the pelletizing process, mist water is sprayed to prepare pretreated mixed iron-containing dust mud balls. During the ball forming process, a scraper is continuously used to cut the balls in the opposite direction of the disc pelletizing machine to prevent the balls from being too dense and to form irregular shapes. The particle size of the balls is controlled to be Φ2~6mm.

[0017] (6) The pre-treated mixed iron-containing dust pellets are transported to a drum mixer, and mixed material A is added at the same time. The pre-treated mixed iron-containing dust pellets are used as the granulation core and mixed material A is used as the attachment material to prepare a sintering mixture. The sintering mixture is distributed to the sintering trolley for sintering production.

[0018] Furthermore, the pelletizing time in step (5) is 10 to 12 minutes, the rotation speed of the disc pelletizing machine is 23 to 28 r / min, and the inclination angle of the disc pelletizing machine is 48° to 55°.

[0019] Furthermore, the weight percentage of moisture content of the sintering mixture in step (6) is 6.5% to 8.5%. The weight percentage of the particle size composition of the sintering mixture is 45% to 50% for the 3 to 5 mm size fraction, 40% to 45% for the 5 to 8 mm size fraction, and 5% to 10% for the size fraction larger than 8 mm. The material temperature of the sintering mixture is 55 to 70°C.

[0020] Furthermore, in the step (6), the height of the sintering material layer from the sintering mixture to the sintering trolley is 700-850 mm, and the negative pressure of the exhaust during the sintering process is 9500-12500 KPa.

[0021] Furthermore, the basicity of the pretreated mixed iron-containing dust sludge in step (4) is 1.7-1.9, and the weight percentage of MgO is 1.4%-1.5%.

[0022] Furthermore, the weight percentage of the moisture content of the pretreated mixed iron-containing dust and mud pellets in step (5) is 6% to 7%.

[0023] Furthermore, the basicity value of the mixture A in step (6) and the sintering mixture is the same as 1.85 to 2.15, and the weight percentage of MgO is 1.5% to 1.7%.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention realizes the purpose of using a large proportion of iron-containing dust and sludge as raw materials to prepare sintering mixture and produce sinter, and overcomes the problems that directly using iron-containing dust and sludge as raw materials to prepare sintering mixture leads to poor strength of the sintering mixture and unreasonable particle size composition, thus deteriorating the output and quality of sinter.

[0026] 2. The present invention solves the problem that iron-containing dust and sludge cannot be effectively utilized in iron and steel enterprises, returns the waste in some production processes of iron and steel enterprises as secondary resources to the sintering production process, broadens the raw material usage conditions for sinter production, and reduces the production cost of sinter.

[0027] 3. Through the treatment of iron-containing dust and sludge, the present invention enables the iron-containing dust and sludge particles to be in full contact with the coke powder particles, provides favorable conditions for the reduction of alkali metals such as potassium and sodium in the iron-containing dust and sludge, enables such harmful elements to be removed during the sintering process, overcomes the problem that a large amount of alkali metals brought in by the iron-containing dust and sludge are enriched in the sinter and enter the blast furnace to erode the hearth, and improves the service life of the blast furnace. Specific Embodiments

[0028] The following further describes the specific embodiments of the present invention:

[0029] Example 1

[0030] The blast furnace sludge, converter sludge, and sinter machine tail dust in the iron-containing dust and sludge of the steel plant are respectively dried and crushed to remove the agglomerated lumps. After crushing, the weight percentage of the particle size composition less than 0.074 mm particle size grade is 100%. The coke powder, magnesite powder, and hydrated lime powder used in sinter production are respectively finely ground. After treatment, the weight percentage of the particle size composition less than 0.05 mm particle size grade is 100% to obtain finely ground coke powder, finely ground magnesite powder, and finely ground hydrated lime powder. The industrial component weight percentages of the coke powder are: fixed carbon 83.6%, ash 12.1%, volatile matter 2.3%, moisture 2%, and the rest are impurities; the chemical component weight percentages of the magnesite powder are as follows: CaO: 2.8%, MgO: 42.6%, SiO2: 11.9%, Al2O3: 0.8%, and the balance are impurity elements; the hydrated lime powder is hydrated lime with a high specific surface area, and its specific surface area is 320,000 cm 2 / g; the blast furnace sludge, converter sludge, and sinter machine tail dust after crushing treatment are fully mixed according to the weight percentages of 22%: 11%: 67% respectively to obtain a mixed iron-containing dust and sludge; the chemical component weight percentages of the mixed iron-containing dust and sludge are as follows: TFe: 56.6%, CaO: 7.8%, MgO: 3.2%, SiO2: 4.1%, Al2O3: 1.3%, and the balance are impurity elements.

[0031] Mix magnetite concentrate, powdered ore, and mixed iron-containing dust and sludge in a weight percentage of 25%:65%:10% respectively, and add limestone powder, magnesite powder, and coke powder in an externally added form to obtain mixture A. The basicity value of mixture A is 1.95, and the weight percentage of MgO is 1.6.

[0032] Mix mixed iron-containing dust and sludge, finely ground coke powder, finely ground magnesite powder, and finely ground slaked lime powder in a weight percentage of 87%:3%:5%:5% in a high-intensity mixer to fully mix them, so that the particles of mixed iron-containing dust and sludge are in full contact with the particles of coke powder, magnesite, and slaked lime, and obtain pretreated mixed iron-containing dust and sludge. The basicity value of the pretreated mixed iron-containing dust and sludge is 1.82, and the weight percentage of MgO is 1.43.

[0033] Transport the pretreated mixed iron-containing dust and sludge to a disk pelletizer for pelletizing. Spray atomized water during the pelletizing process to prepare small balls of pretreated mixed iron-containing dust and sludge. During the pelletizing process, continuously cut against the rotation direction of the disk pelletizer with a scraper. Control the particle size of the small balls to be Φ2 - 6mm, and the weight percentage of the moisture content is 6.5%. The pelletizing time is 10 minutes, the rotation speed of the disk pelletizer is 23 r / min, and the inclination angle of the disk pelletizer is 48°.

[0034] Transport the small balls of pretreated mixed iron-containing dust and sludge to a cylindrical mixer, and at the same time add mixture A. Use the small balls of pretreated mixed iron-containing dust and sludge as the granulation core and mixture A as the adhering material to grow, and prepare sintering mixture; the weight percentage of the moisture content of the sintering mixture is 6.5%. The particle size composition of the sintering mixture: the weight percentage of the particle size range of 3 - 5mm is 45%, the weight percentage of the particle size range of 5 - 8mm is 45%, and the weight percentage of the particle size range greater than 8mm is 10%. The temperature of the sintering mixture is 55°C, the basicity value is 1.95, and the weight percentage of MgO is 1.6. Distribute the sintering mixture onto the sintering trolley for sintering production. The height of the sintering material layer in the sintering production process is 700mm, and the suction negative pressure during the sintering process is 9500 KPa.

[0035] To compare the application effects of the present invention, in Comparative Example 1, mix magnetite concentrate and powdered ore, and add limestone powder, magnesite powder, and coke powder in an externally added form to obtain a mixture. Keep other process parameters the same. The temperature of the mixture is 55°C, the basicity value is 1.95, and the weight percentage of MgO is 1.6. The height of the sintering material layer in the sintering production process is 700mm, and the suction negative pressure during the sintering process is 9500 KPa.

[0036] Table 1 Comparison of K2O and Na2O Contents in Sintered Ore between Example 1 and Comparative Example 1

[0037] <![CDATA[K2O]]> <![CDATA[Na2O]]> Example 1 0.026 0.018 Comparative Example 1 0.171 0.078

[0038] It can be seen from the comparison results that, compared with Comparative Example 1, the contents of K2O and Na2O in the sinter of Example 1 are significantly reduced. The content of K2O is reduced by nearly 85 percentage points, and the content of Na2O is reduced by nearly 77 percentage points.

[0039] After the application of the present invention, the drum strength of the sinter is increased from 81.77% to 86.78%, and the solid fuel consumption for sintering is reduced from 51.4 kg / t to 46.2 kg / t. The improvement effect of the sinter weight and the reduction degree of the solid fuel consumption are significant.

[0040] Example 2

[0041] The blast furnace gas sludge, converter sludge, and sinter machine tail dust in the iron-containing dust and sludge of the steel plant are respectively dried and crushed to remove the agglomerated lumps. After crushing, the weight percentage of the particle size fraction less than 0.074 mm is 100%. The coke powder, magnesite powder, and hydrated lime powder used in sintering production are respectively finely ground. After processing, the weight percentage of the particle size fraction less than 0.05 mm is 100%, obtaining finely ground coke powder, finely ground magnesite powder, and finely ground hydrated lime powder. The industrial component weight percentages of the coke powder are as follows: fixed carbon 85.8%, ash 11.1%, volatile matter 1.3%, moisture 1.8%, and the rest are impurities; the chemical component weight percentages of the magnesite powder are as follows: CaO: 2.1%, MgO: 44.8%, SiO2: 10.3%, Al2O3: 1.8%, and the balance is impurity elements; the hydrated lime powder is hydrated lime with a high specific surface area, and its specific surface area is 380000 cm 2 / g; the blast furnace gas sludge, converter sludge, and sinter machine tail dust after crushing treatment are fully mixed according to the weight percentages of 22%: 8%: 70% respectively to obtain a mixed iron-containing dust and sludge; the chemical component weight percentages of the mixed iron-containing dust and sludge are as follows: TFe: 60%, CaO: 5.8%, MgO: 4.2%, SiO2: 2.1%, Al2O3: 2.3%, and the balance is impurity elements.

[0042] The iron concentrate, powder ore, and mixed iron-containing dust and sludge are mixed and processed according to the weight percentages of 50%: 35%: 15% respectively, and limestone powder, magnesite powder, and coke powder are added in an externally added form to obtain mixture A. The basicity value of mixture A is 2.15, and the weight percentage of MgO is 1.7.

[0043] The mixed iron-containing dust and sludge, finely ground coke powder, finely ground magnesite powder, and finely ground hydrated lime powder are fully mixed in a high-intensity mixer according to the weight percentages of 90%: 6%: 2%: 2% respectively, so that the particles of the mixed iron-containing dust and sludge are in full contact with the coke powder, magnesite, and hydrated lime particles, obtaining pre-treated mixed iron-containing dust and sludge. The basicity value of the pre-treated mixed iron-containing dust and sludge is 1.9, and the weight percentage of MgO is 1.5.

[0044] The pretreated mixed iron-bearing dust and sludge is conveyed to a disk pelletizer for pelletizing. During the pelletizing process, atomized water is sprayed to prepare small balls of the pretreated mixed iron-bearing dust and sludge. During the ball forming process, a scraper is continuously used to cut against the rotation direction of the disk pelletizer. The particle size of the small balls is controlled to be Φ2 - 6 mm, and the moisture content is 7% by weight. The pelletizing time is 12 minutes, the rotation speed of the disk pelletizer is 28 r / min, and the inclination angle of the disk pelletizer is 55°.

[0045] The small balls of the pretreated mixed iron-bearing dust and sludge are conveyed to a cylindrical mixer, and at the same time, mixture A is added. Using the small balls of the pretreated mixed iron-bearing dust and sludge as the granulation core and mixture A as the adhering material to grow, sintering mixture is prepared. The moisture content of the sintering mixture is 7.5% by weight. In the particle size composition of the sintering mixture, the weight percentage of the particle size range of 3 - 5 mm is 50%, the weight percentage of the particle size range of 5 - 8 mm is 43%, and the weight percentage of the particle size range greater than 8 mm is 7%. The temperature of the sintering mixture is 68 °C, the basicity value is 2.15, and the weight percentage of MgO is 1.7. The sintering mixture is fed onto a sintering trolley for sintering production. In the sintering production process, the height of the sintering material layer is 850 mm, and the suction negative pressure during sintering is 12500 KPa.

[0046] To compare the implementation and application effects of the present invention, in Comparative Example 2, iron concentrate and fine ore are mixed evenly, and limestone powder, magnesite powder, and coke powder are added in the form of external addition to obtain a mixture. Other process parameters remain the same. The temperature of the mixture is 68 °C, the basicity value is 2.15, and the weight percentage of MgO is 1.7. In the sintering production process, the height of the sintering material layer is 850 mm, and the suction negative pressure during sintering is 12500 KPa.

[0047] Table 2 Comparison of K2O and Na2O Contents in Sintered Ore between Example 2 and Comparative Example 2

[0048] <![CDATA[K2O]]> <![CDATA[Na2O]]> Example 2 0.021 0.013 Comparative Example 2 0.182 0.083

[0049] It can be seen from the comparison results that compared with Comparative Example 2, the contents of K2O and Na2O in the sintered ore of Example 1 are significantly reduced. The content of K2O is reduced by nearly 88 percentage points, and the content of Na2O is reduced by nearly 84 percentage points.

[0050] After the implementation and application of the present invention, the drum strength of the sintered ore is increased from 82.01% to 88.65%, the consumption of sintered solid fuel is reduced from 51.8 kg / t to 44.3 kg / t, and the improvement effect of the weight of the sintered ore and the reduction degree of the solid fuel consumption are remarkable.

[0051] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and its concept of the present invention, making equivalent substitutions or changes should be covered within the protection scope of the present invention.

Claims

1. A sintering mixture, comprising mixed iron-containing dust and sludge, iron concentrate, powdered ore, coke powder, magnesite powder and hydrated lime powder, characterized in that The described mixed iron-containing dust and sludge includes blast furnace gas sludge, converter sludge, and sinter machine tail dust, which are fully mixed in a weight percentage of 20% - 25%: 8% - 15%: 65% - 70% to obtain the mixed iron-containing dust and sludge.

2. The sintering mixture according to claim 1, wherein The chemical composition weight percentages of the described mixed iron-containing dust and sludge are as follows: TFe: 55% - 60%, CaO: 5% - 10%, MgO: 2% - 5%, SiO2: 1% - 7%, Al2O3: 0.5% - 3%, and the balance is impurity elements.

3. A sintering mixture according to claim 1, characterized in that, The chemical composition of the iron concentrate by weight percentage is as follows: TFe: 67% - 70%, FeO: 9% - 31%, CaO: 0.05% - 0.3%, MgO: 0.1% - 0.5%, SiO2: 3% - 6%, Al2O3: 0.1% - 0.3%, and the balance is impurity elements; the chemical composition of the powdered ore by weight percentage is: TFe: 50% - 66%, FeO: 0.2% - 2%, CaO: 0.1% - 0.5%, MgO: 0.1% - 0.5%, SiO2: 3% - 7%, Al2O3: 1.5% - 7%, and the balance is impurity elements; the industrial composition of the coke powder by weight percentage is: fixed carbon 80% - 86%, ash 11% - 14%, volatile matter 1% - 4%, moisture 0.5% - 3%, and the rest is impurities; the chemical composition of the magnesite powder by weight percentage is: CaO: 2% - 5%, MgO: 42% - 45%, SiO2: 10% - 13%, Al2O3: 0.5% - 2%, and the balance is impurity elements; the slaked lime powder is high specific surface area slaked lime, and its specific surface area is 300,000 - 400,000 cm 2 / g.

4. A method for preparing a sintering mixture according to claim 1, characterized in that, The described preparation method includes the following steps: (1) Respectively perform drying and crushing treatments on the blast furnace gas sludge, converter sludge, and sinter machine tail dust in the iron-containing dust and sludge to remove the agglomerated lumps, and the particle size after crushing is less than 0.074 mm; (2) Respectively perform fine grinding treatments on the coke powder, magnesite powder, and slaked lime powder used in sintering production. After the fine grinding treatment, the particle size is less than the 0.05 mm particle size grade to obtain fine-ground coke powder, fine-ground magnesite powder, and fine-ground slaked lime powder; (3) Mix and process the iron concentrate, powder ore, and mixed iron-containing dust and sludge in a weight percentage of 15% - 55%: 35% - 70%: 10% - 15%, and add limestone powder, magnesite powder, and coke powder in an externally added form to obtain mixture A; (4) Fully mix the mixed iron-containing dust and sludge, fine-ground coke powder, fine-ground magnesite powder, and fine-ground slaked lime powder in a weight percentage of 85% - 90%: 2% - 6%: 2% - 5%: 2% - 6% in a high-strength mixer, so that the particles of the mixed iron-containing dust and sludge are in full contact with the coke powder, magnesite, and slaked lime particles to obtain the pretreated mixed iron-containing dust and sludge; (5) Transport the pretreated mixed iron-containing dust and sludge to a disk pelletizer for pelletizing. During the pelletizing process, spray atomized water to prepare the pretreated mixed iron-containing dust and sludge pellets. During the pellet formation process, continuously cut against the rotation direction of the disk pelletizer with a scraper to prevent the pellets from being overly dense and promote the formation of irregular shapes. The pellet particle size is controlled to be Φ2 - 6 mm; (6) Transport the pretreated mixed iron-containing dust and sludge pellets to a cylindrical mixer, and at the same time add mixture A. Using the pretreated mixed iron-containing dust and sludge pellets as the granulation core and mixture A as the adhering material, prepare the sintering mixture, and distribute the sintering mixture onto the sintering trolley for sintering production.

5. The preparation method of the sintering mixture according to claim 4, wherein The pelletizing time in the step (5) is 10 - 12 minutes, the rotation speed of the disk pelletizer is 23 - 28 r / min, and the inclination angle of the disk pelletizer is 48° - 55°.

6. The preparation method of the sintering mixture according to claim 4, characterized in that, The weight percentage of the moisture content of the sintering mixture in the step (6) is 6.5% - 8.5%; the weight percentage of the particle size composition of the sintering mixture with a particle size of 3 - 5 mm is 45% - 50%; the weight percentage of the particle size composition of 5 - 8 mm is 40% - 45%; the weight percentage of the particle size composition greater than 8 mm is 5% - 10%; the temperature of the sintering mixture is 55 - 70 °C.

7. The preparation method of the sintering mixture according to claim 4, characterized in that, The height of the sintering material layer when the sintering mixture in the step (6) is distributed onto the sintering trolley is 700 - 850 mm, and the suction negative pressure during the sintering process is 9500 - 12500 KPa.

8. The method for preparing the sintering mixture according to claim 4, characterized in that, The basicity value of the pretreated mixed iron-containing dust and sludge in step (4) is 1.7 - 1.9, and the weight percentage of MgO is 1.4% - 1.5%.

9. The preparation method of the sintering mixture according to claim 4, characterized in that, The weight percentage of the moisture content of the pretreated mixed iron-containing dust and sludge pellets in step (5) is 6% - 7%.

10. The preparation method of the sintering mixture according to claim 4, characterized in that, The basicity values of the mixture A and the sintering mixture in step (6) are both 1.85 - 2.15, and the weight percentage of MgO is 1.5% - 1.7%.