Method for matching coarse-fraction flux type steel slag magnetic separation tailings in iron ore sintering

Abstract

According to the matching method of the coarse-grained flux-type steel slag magnetic separation tailings in iron ore sintering, the flux-type steel slag magnetic separation tailings are innovatively mixed and screened to obtain the coarse-grained flux-type steel slag magnetic separation tailings, and the coarse-grained flux-type steel slag magnetic separation tailings are used for iron ore sintering production, so that the composition fluctuation is reduced, and the production efficiency is improved. The granulating effect of the steel slag raw material is improved. A high-alkalinity sintering raw material is further obtained through burdening calculation, and combined control over the content of MgO, the use amount of solid fuel, the water content of a sintering mixture, the use amount of a sintering grate-layer material, the height of a sintering material layer and the rotating speed of a sintering exhaust fan is matched, so that the problem that the coarse-fraction flux type steel slag magnetic separation tailings are used for iron ore production is successfully solved; and the sintering effect is enhanced, and the sintered ore yield and the drum strength are improved. The granulation effect of the sintering raw material is very good, the sintering effect is improved, the yield reaches 79.80%, the drum strength of the sintered ore reaches 66.53%, and the FeO content reaches 8.77%.

Description

Technical Field

[0001] The invention relates to the fields of metallurgy and iron ore sintering, and in particular to a method for preparing coarse-grained flux-type steel slag magnetic separation tailings in iron ore sintering. Background Art

[0002] Steel slag magnetic separation tailings are solid wastes with an iron grade of less than 35% obtained after the steel slag formed by removing impurities in the steelmaking process is sorted. The content of CaO and MgO in the steel slag magnetic separation tailings is relatively high. Among them, the total content of CaO and MgO in the steel slag magnetic separation tailings is more than twice that of iron, which is called flux-type steel slag magnetic separation tailings. Steel slag contains a large amount of heavy metal pollutants such as Cr, Pb, Mn, Fe, Cu, and Zn. Random stacking and landfill will pollute the soil and water. In addition, steel slag magnetic separation tailings also contain a certain amount of iron resources, which will cause serious waste of resources if they are not recycled.

[0003] In order to solve the problem of recycling steel slag magnetic separation tailings, a variety of treatment methods have been developed, mainly including as building materials such as cement, concrete and building aggregates, as raw materials for iron ore sintering and as phosphate fertilizer or soil conditioner.

[0004] Using slag magnetic separation tailings as building materials is a traditional method of utilizing them. It has a wide range of applications, but its unstable chemical composition limits the further expansion of its application scope. In addition, the product added value is low and the economic benefits are not ideal. Using it as a raw material for iron ore sintering can achieve the treatment of solid waste within steel enterprises, reduce the transportation cost of steel slag treatment, and reduce the purchase and transportation cost of sintering raw materials, with significant economic benefits. However, due to the unevenness and poor granulation performance of slag magnetic separation tailings, it will have an adverse effect on the utilization coefficient of the sintering machine and the iron grade, yield, drum strength and reducibility of the sintered ore. Using it as a phosphate fertilizer or soil conditioner requires a very high phosphorus content in the slag magnetic separation tailings, requiring the P2O5 content to exceed 10% and 4%~7% respectively, which exceeds the phosphorus content of slag magnetic separation tailings in most steel enterprises.

[0005] Therefore, the efficient and comprehensive treatment of steel slag magnetic separation tailings still needs to overcome many technical bottlenecks. Summary of the invention

[0006] The present invention provides a method for using coarse-grained flux-type steel slag magnetic separation tailings in iron ore sintering, the purpose of which is to solve the problems of uneven composition of steel slag magnetic separation tailings, high SiO2 content, poor granulation performance, and adverse effects on the sintering machine utilization factor and the iron grade, finished product rate, drum strength and reducibility of the sintered ore.

[0007] In order to achieve the above object, an embodiment of the present invention provides a method for using coarse-grained flux-type steel slag magnetic separation tailings in iron ore sintering, comprising the following steps: S1: Mixing and screening the flux type steel slag magnetic separation tailings to obtain coarse particle size flux type steel slag magnetic separation tailings; S2: Calculate the amount of water to be added based on the proportion of coarse-grained flux-type steel slag magnetic separation tailings, iron-containing raw materials, flux and solid fuel to obtain the required amount of sintering raw materials; S3: mixing and granulating the sintering raw materials after quicklime and magnesian lime digestion according to the said proportion of ingredients to obtain a sintering mixture; S4: sintering the sintered mixture with exhaust air to obtain sintered ore; Among them, flux-type steel slag magnetic separation tailings contain 30%~40% CaO, 10%~15% SiO2, 10%~15% MgO, 5%~10% Al2O3, 10%~15% TFe, 8%~10% FeO, among which the burn loss of flux-type steel slag magnetic separation tailings is 1%~4%; the coarse particle size of coarse particle flux-type steel slag magnetic separation tailings is +3 mm; it should be noted that the higher the TFe content in flux-type steel slag magnetic separation tailings, the more iron-containing raw materials can be replaced, the higher the CaO and MgO content, the more replaceable flux, and the more obvious the economic benefit. The ratio of CaO, SiO2 and TFe content has a significant effect on the formation process of liquid phase, especially calcium ferrite. A higher SiO2 content and a lower TFe content will limit the formation of calcium ferrite. The iron in flux-type steel slag magnetic separation tailings mainly exists in the form of single substance and FeO. The higher its content, the higher the latent heat, which is more conducive to improving the sintering effect. Under the condition that the basicity of sintering raw materials remains unchanged, the lower the basicity of flux-type steel slag magnetic separation tailings, the lower the iron grade of the sintered ore. Therefore, the higher the basicity of flux-type steel slag magnetic separation tailings, the higher its application value.

[0008] The content of coarse-grained flux-type steel slag magnetic separation tailings in the sintering raw materials is 2%~4%; the content of solid fuel in the sintering raw materials is 2.7%~3.2%; the basicity of the sintering raw materials 1.7~2. According to the composition characteristics of coarse-grained flux-type steel slag magnetic separation tailings, under the condition of ensuring the ratio of quicklime, the basicity and MgO content of the sintering raw materials are regulated by magnesian lime, limestone powder and dolomite powder. While realizing the high-value utilization of coarse-grained flux-type steel slag magnetic separation tailings, the latent heat of the steel slag magnetic separation tailings is used to improve the yield rate of sintered ore and the drum strength.

[0009] According to one aspect of the embodiment of the present invention, in step S1, the mixing process adopts the stacking method, the stacking amount is 30-40 kg, and the stacking times are 3-4 times; the screening process adopts Manual screening with a standard sieve takes 2 to 3 minutes. The composition of flux-type steel slag magnetic separation tailings fluctuates greatly, which will seriously deteriorate the sintering effect. Therefore, it is very necessary to mix the steel slag magnetic separation tailings before use. In addition, using +3 mm coarse-grained flux-type steel slag magnetic separation tailings to prepare sintering mixtures can avoid the influence of the insufficient granulation performance of steel slag magnetic separation tailings on the granulation effect, thereby improving the permeability of the sintering material layer and enhancing the sintering effect.

[0010] According to one aspect of the embodiments of the present invention, in step S1, the proportion of +5 mm particle size in the coarse-grained flux-type steel slag magnetic separation tailings is 50% to 60%.

[0011] According to one aspect of the embodiment of the present invention, in step S2, the iron-containing raw material is at least one of powder ore, sintering fine powder, pelletizing fine powder, iron oxide scraps, iron-containing dust and sintering return ore, the particle size of +3 mm accounts for 25% to 28%, and the particle size of -0.5 mm accounts for 40% to 44%; the TFe content of the iron-containing raw material is 58% to 60%, and the proportion of sintering return ore is 20% to 22%. Among them, the powder ore includes domestic low-grade powder ore, domestic high-grade powder ore, imported powder ore, etc.

[0012] According to one aspect of an embodiment of the present invention, in step S2, the flux is at least one of quicklime, magnesian lime, limestone powder and dolomite powder, the proportion of -3 mm particle size in quicklime is 98%~99.5%, the proportion of -3 mm particle size in magnesian lime is 95%~98%, the proportion of -3 mm particle size in limestone powder is 75%~80%, and the proportion of -3 mm particle size in dolomite powder is 75%~80%; wherein, the CaO content of quicklime is 78%~82%, the burn loss is 9.5%~10.5%, and the activity is 310~320mL; the CaO content of magnesian lime is 55%~59%, the MgO content is 30%~33%, the burn loss is 7%~8%, and the activity is 250~260mL; the fixed carbon content of coke powder is 81%~84%, and the ash content is 14%~15%.

[0013] According to one aspect of an embodiment of the present invention, in step S2, the solid fuel is coke powder, and the -3 mm particle size accounts for 90% to 93%; the fixed carbon content of the coke powder is 81% to 84%, and the ash content is 14% to 15%.

[0014] According to one aspect of the embodiment of the present invention, in step S2, the basicity of the sintering raw material The content of CaO in the sintering raw materials is 3.4%~3.9%, the content of MgO in the sintering raw materials is 2.5%~2.8%, and the content of solid fuel is 2.8%~3.1%. It should be noted that part of the CaO and MgO in the sintering raw materials exists in the large particles of magnetic separation tailings of steel slag, which will reduce the alkalinity of the liquid phase during the sintering process. Therefore, it is very necessary to select sintering raw materials with high alkalinity and a certain amount of MgO.

[0015] According to one aspect of the embodiment of the present invention, in step S3, the molar ratio of CaO to digestion water in the sintering raw material is 1:2, and the digestion time is 5 min. The amount of water added during the mixing and granulation process is 0.25 kg, a fixed amount of water added by the drum mixer, and the residual amount of digestion water is 50%.

[0016] According to one aspect of an embodiment of the present invention, in step S3, the water content of the sintered mixture is 8.4%~9%; the mixing granulation equipment includes a disc mixer and a drum granulator; wherein the filling rate of the disc mixer is 18%~20%, the rotation speed is 15 r / min, and the mixing time is 180 s; the filling rate of the drum granulator is 10%~12%, the rotation speed is 12 r / min, and the mixing time is 300 s.

[0017] According to one aspect of the embodiment of the present invention, in step S4, the sintering ignition temperature is 1100-1150°C, and the ignition time is 90 s. The sintering process is carried out in a sintering cup, wherein the sintering cup has a height of 720 mm and an inner diameter of 290 mm; the particle size of the base material for sintering is 10-20 mm; the amount of base material is 2.8 kg-3.1 kg; the material layer height is 660-720 mm; and the exhaust fan speed is 1800-2000 r / min.

[0018] Principle / Mechanism Description The present invention innovatively mixes and screens flux-type steel slag magnetic separation tailings to obtain coarse-grained flux-type steel slag magnetic separation tailings, and uses them in iron ore sintering production, thereby reducing component fluctuations and improving the granulation effect of steel slag raw materials. Further, a high-basicity sintering raw material is obtained through batching calculation, and the MgO content, solid fuel dosage, sintering mixture moisture content, sintering base material dosage, sintering material layer height and sintering exhaust fan speed are combined to successfully solve the problem of using coarse-grained flux-type steel slag magnetic separation tailings for iron ore production, enhance the sintering effect, and improve the sintering ore yield and drum strength.

[0019] The above scheme of the present invention has the following beneficial effects: The granulation effect of the sintering raw material of the present invention is very good. The proportion of sintering mixed material particles with a particle size of +3 mm can reach 66.48%, and the air permeability index of the sintering material layer reaches 322 m·(kPa·h)-1 ; The sintering effect has been improved, exceeding the benchmark test results, with a yield rate of 79.80% and a utilization factor of 1.78 t·h -1 ·m -2 The sintered ore drum strength reached 66.53% and the FeO content reached 8.77%. DETAILED DESCRIPTION

[0020] In order to make the technical problems to be solved, technical solutions and advantages of the present invention more clear, they are described in detail below in conjunction with specific embodiments.

[0021] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0022] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0023] In view of the existing problems, the present invention provides a method for using coarse-grained flux-type steel slag magnetic separation tailings in iron ore sintering, comprising the following steps: S1: Mixing and screening the flux type steel slag magnetic separation tailings to obtain coarse particle size flux type steel slag magnetic separation tailings; S2: Calculate the amount of water to be added based on the proportion of coarse-grained flux-type steel slag magnetic separation tailings, iron-containing raw materials, flux and solid fuel to obtain the required amount of sintering raw materials; S3: mixing and granulating the sintering raw materials after quicklime and magnesian lime digestion according to the said proportion of ingredients to obtain a sintering mixture; S4: sintering the sintered mixture with exhaust air to obtain sintered ore; Among them, flux-type steel slag magnetic separation tailings contain 30%~40% CaO, 10%~15% SiO2, 10%~15% MgO, 5%~10% Al2O3, 10%~15% TFe, 8%~10% FeO, among which the burn loss of flux-type steel slag magnetic separation tailings is 1%~4%; the coarse particle size of coarse particle flux-type steel slag magnetic separation tailings is +3 mm; it should be noted that the higher the TFe content in flux-type steel slag magnetic separation tailings, the more iron-containing raw materials can be replaced, the higher the CaO and MgO content, the more replaceable flux, and the more obvious the economic benefit. The ratio of CaO, SiO2 and TFe content has a significant effect on the formation process of liquid phase, especially calcium ferrite. A higher SiO2 content and a lower TFe content will limit the formation of calcium ferrite. The iron in flux-type steel slag magnetic separation tailings mainly exists in the form of single substance and FeO. The higher its content, the higher the latent heat, which is more conducive to improving the sintering effect. Under the condition that the basicity of sintering raw materials remains unchanged, the lower the basicity of flux-type steel slag magnetic separation tailings, the lower the iron grade of the sintered ore. Therefore, the higher the basicity of flux-type steel slag magnetic separation tailings, the higher its application value.

[0024] The content of coarse-grained flux-type steel slag magnetic separation tailings in the sintering raw materials is 2%~4%; the content of solid fuel in the sintering raw materials is 2.7%~3.2%; the basicity of the sintering raw materials 1.7~2. According to the composition characteristics of coarse-grained flux-type steel slag magnetic separation tailings, under the condition of ensuring the ratio of quicklime, the basicity and MgO content of the sintering raw materials are regulated by magnesian lime, limestone powder and dolomite powder. While realizing the high-value utilization of coarse-grained flux-type steel slag magnetic separation tailings, the latent heat of the steel slag magnetic separation tailings is used to improve the yield rate of sintered ore and the drum strength.

[0025] According to one aspect of the embodiment of the present invention, in step S1, the mixing process adopts the stacking method, the stacking amount is 30-40 kg, and the stacking times are 3-4 times; the screening process adopts Manual screening with a standard sieve takes 2 to 3 minutes. The composition of flux-type steel slag magnetic separation tailings fluctuates greatly, which will seriously deteriorate the sintering effect. Therefore, it is very necessary to mix the steel slag magnetic separation tailings before use. In addition, using +3 mm coarse-grained flux-type steel slag magnetic separation tailings to prepare sintering mixtures can avoid the influence of the insufficient granulation performance of steel slag magnetic separation tailings on the granulation effect, thereby improving the permeability of the sintering material layer and enhancing the sintering effect.

[0026] According to one aspect of the embodiments of the present invention, in step S1, the proportion of +5 mm particle size in the coarse-grained flux-type steel slag magnetic separation tailings is 50% to 60%.

[0027] According to one aspect of the embodiment of the present invention, in step S2, the iron-containing raw material is at least one of powder ore, sintering fine powder, pelletizing fine powder, iron oxide scraps, iron-containing dust and sintering return ore, the particle size of +3 mm accounts for 25% to 28%, and the particle size of -0.5 mm accounts for 40% to 44%; the TFe content of the iron-containing raw material is 58% to 60%, and the proportion of sintering return ore is 20% to 22%. Among them, the powder ore includes domestic low-grade powder ore, domestic high-grade powder ore, imported powder ore, etc.

[0028] According to one aspect of an embodiment of the present invention, in step S2, the flux is at least one of quicklime, magnesian lime, limestone powder and dolomite powder, the proportion of -3 mm particle size in quicklime is 98%~99.5%, the proportion of -3 mm particle size in magnesian lime is 95%~98%, the proportion of -3 mm particle size in limestone powder is 75%~80%, and the proportion of -3 mm particle size in dolomite powder is 75%~80%; wherein, the CaO content of quicklime is 78%~82%, the burn loss is 9.5%~10.5%, and the activity is 310~320mL; the CaO content of magnesian lime is 55%~59%, the MgO content is 30%~33%, the burn loss is 7%~8%, and the activity is 250~260mL; the fixed carbon content of coke powder is 81%~84%, and the ash content is 14%~15%.

[0029] According to one aspect of an embodiment of the present invention, in step S2, the solid fuel is coke powder, and the -3 mm particle size accounts for 90% to 93%; the fixed carbon content of the coke powder is 81% to 84%, and the ash content is 14% to 15%.

[0030] According to one aspect of the embodiment of the present invention, in step S2, the basicity of the sintering raw material The content of CaO in the sintering raw materials is 3.4%~3.9%, the content of MgO in the sintering raw materials is 2.5%~2.8%, and the content of solid fuel is 2.8%~3.1%. It should be noted that part of the CaO and MgO in the sintering raw materials exists in the large particles of magnetic separation tailings of steel slag, which will reduce the alkalinity of the liquid phase during the sintering process. Therefore, it is very necessary to select sintering raw materials with high alkalinity and a certain amount of MgO.

[0031] According to one aspect of the embodiment of the present invention, in step S3, the molar ratio of CaO to digestion water in the sintering raw material is 1:2, and the digestion time is 5 min. The amount of water added during the mixing and granulation process is 0.25 kg, a fixed amount of water added by the drum mixer, and the residual amount of digestion water is 50%.

[0032] According to one aspect of an embodiment of the present invention, in step S3, the water content of the sintered mixture is 8.4%~9%; the mixing granulation equipment includes a disc mixer and a drum granulator; wherein the filling rate of the disc mixer is 18%~20%, the rotation speed is 15 r / min, and the mixing time is 180 s; the filling rate of the drum granulator is 10%~12%, the rotation speed is 12 r / min, and the mixing time is 300 s.

[0033] According to one aspect of the embodiment of the present invention, in step S4, the sintering ignition temperature is 1100-1150°C, and the ignition time is 90 s. The sintering process is carried out in a sintering cup, wherein the sintering cup has a height of 720 mm and an inner diameter of 290 mm; the particle size of the base material for sintering is 10-20 mm; the amount of base material is 2.8 kg-3.1 kg; the material layer height is 660-720 mm; and the exhaust fan speed is 1800-2000 r / min.

[0034] The "%" mentioned in this article refers to the mass percentage content, among which "alkalinity ” specifically refers to the mass ratio of calcium oxide to silicon dioxide.

[0035] The main chemical compositions of flux-type steel slag magnetic separation tailings, iron-containing raw materials, quicklime, magnesian lime, limestone powder, dolomite powder and coke powder in this paper are shown in Tables 1 and 2 below.

[0036] Table 1 Chemical composition of raw materials used in iron ore sintering / %

[0037] Table 2 Industrial analysis of coke powder / %

[0038] The following will describe the invention through specific embodiments.

[0039] Example 1 This embodiment provides a method for using coarse-grained flux-type steel slag magnetic separation tailings in iron ore sintering.

[0040] The method of this embodiment specifically includes the following steps: Step (1) The flux type steel slag magnetic separation tailings were mixed for 4 times and then sieved to obtain the coarse particle size of +3 mm flux type steel slag magnetic separation tailings.

[0041] Step (2) The calculated content of coarse-grained flux-type steel slag magnetic separation tailings is 3%, the content of quicklime is 3.8%, the content of coke powder is 2.9%, the basicity is 1.8, the content of MgO is 2.6%, the wet weight of sintering raw materials is 84-86 kg, the moisture content of sintering mixture is 8.7%, and the amount of water added to the disc mixer is 8.

[0042] Step (3) The quicklime and magnesia lime calculated and weighed in step (2) are fed into a disc mixer and a drum granulator to mix and granulate the sintered raw materials, and water is added to obtain a sintered mixed material.

[0043] The sintered mixture obtained in Example 1 has a particle size of +3 mm accounting for 60.01%.

[0044] Step (4) The sintered mixture was placed in a sintering cup covered with 3.2 kg of base material, the material layer height was controlled to be 700 mm, and sintering was ignited at a fan speed of 1900 r / min to obtain sintered ore.

[0045] The permeability index of the sintered material layer obtained in Example 1 is between 284 and 322 m·(kPa·h) -1 The sintered ore yield is 77.23% and the sintering cup utilization coefficient is 1.76 t·h -1 ·m -2 The drum strength of the sintered ore is 63.45%, and the FeO content of the sintered ore is 9.48%.

[0046] Example 2 This embodiment provides a method for using coarse-grained flux-type steel slag magnetic separation tailings in iron ore sintering.

[0047] The method of this embodiment specifically includes the following steps: Step (1) The flux type steel slag magnetic separation tailings were mixed for 4 times and then sieved to obtain the coarse particle size of +3 mm flux type steel slag magnetic separation tailings.

[0048] Step (2) The calculated content of coarse-grained flux-type steel slag magnetic separation tailings is 2%, the content of quicklime is 3.4%, the content of coke powder is 3%, the basicity is 1.75, the content of MgO is 2.7%, the wet weight of sintering raw materials is 84~86 kg, the moisture content of sintering mixture is 9.0%, the amount of sintering raw materials and the amount of water added to the disc mixer are

[0049] Step (3) The quicklime and magnesia lime calculated and weighed in step (2) are fed into a disc mixer and a drum granulator to mix and granulate the sintered raw materials, and water is added to obtain a sintered mixed material.

[0050] The sintered mixture obtained in Example 2 has a particle size of +3 mm accounting for 63.78%.

[0051] Step (4) The sintered mixture was placed in a sintering cup covered with 2.8 kg of base material, the material layer height was controlled to be 720 mm, and sintering was ignited at a fan speed of 1900 r / min to obtain sintered ore.

[0052] The permeability index of the sintered material layer obtained in Example 2 is between 265 and 305 m·(kPa·h) -1 The sintered ore yield is 78.06%, and the sintering cup utilization coefficient is 1.67 t·h -1 ·m -2 The drum strength of the sintered ore is 64.28%, and the FeO content of the sintered ore is 8.92%.

[0053] Example 3 This embodiment provides a method for using coarse-grained flux-type steel slag magnetic separation tailings in iron ore sintering.

[0054] The method of this embodiment specifically includes the following steps: Step (1) The flux type steel slag magnetic separation tailings were mixed for 4 times and then sieved to obtain the coarse particle size of +3 mm flux type steel slag magnetic separation tailings.

[0055] Step (2) The calculated content of coarse-grained flux-type steel slag magnetic separation tailings is 3%, the content of quicklime is 3.6%, the content of coke powder is 2.9%, the basicity is 1.85, the content of MgO is 2.7%, the wet weight of sintering raw materials is 84-86 kg, the moisture content of sintering mixture is 9.0%, the amount of sintering raw materials and the amount of water added to the disc mixer are calculated.

[0056] Step (3) The quicklime and magnesia lime calculated and weighed in step (2) are fed into a disc mixer and a drum granulator to mix and granulate the sintered raw materials, and water is added to obtain a sintered mixed material.

[0057] The sintered mixture obtained in Example 3 has a particle size of +3 mm accounting for 57.20%.

[0058] Step (4) The sintered mixture was placed in a sintering cup covered with 3 kg of base material, the material layer height was controlled to be 720 mm, and sintering was ignited at a fan speed of 1950 r / min to obtain sintered ore.

[0059] The permeability index of the sintered material layer obtained in Example 3 is between 278 and 322 m·(kPa·h) -1 The sintered ore yield is 76.98%, and the sintering cup utilization coefficient is 1.74 t·h -1 ·m -2 The drum strength of the sintered ore is 64.48%, and the FeO content of the sintered ore is 9.05%.

[0060] Example 4 This embodiment provides a method for using coarse-grained flux-type steel slag magnetic separation tailings in iron ore sintering.

[0061] The method of this embodiment specifically includes the following steps: Step (1) The flux type steel slag magnetic separation tailings were mixed for 4 times and then sieved to obtain the coarse particle size of +3 mm flux type steel slag magnetic separation tailings.

[0062] Step (2) The calculated content of coarse-grained flux-type steel slag magnetic separation tailings is 4%, the content of quicklime is 3.4%, the content of coke powder is 3%, the basicity is 1.85, the content of MgO is 2.5%, the wet weight of sintering raw materials is 84-86 kg, the moisture content of sintering mixture is 8.7%, and the amount of water added to the disc mixer is 8.7%.

[0063] Step (3) The quicklime and magnesia lime calculated and weighed in step (2) are fed into a disc mixer and a drum granulator to mix and granulate the sintered raw materials, and water is added to obtain a sintered mixed material.

[0064] The sintered mixture obtained in Example 4 has a particle size of +3 mm accounting for 56.42%.

[0065] Step (4) The sintered mixture was placed in a sintering cup covered with 3 kg of base material, the material layer height was controlled to be 700 mm, and sintering was ignited at a fan speed of 1850 r / min to obtain sintered ore.

[0066] The permeability index of the sintered material layer obtained in Example 4 is between 266 and 311 m·(kPa·h) -1 The sintered ore yield is 79.18%, and the sintering cup utilization coefficient is 1.74 t·h -1 ·m -2 The drum strength of the sintered ore is 65.57%, and the FeO content of the sintered ore is 9.08%.

[0067] Example 5 This embodiment provides a method for using coarse-grained flux-type steel slag magnetic separation tailings in iron ore sintering.

[0068] The method of this embodiment specifically includes the following steps: Step (1) The flux type steel slag magnetic separation tailings were mixed for 4 times and then sieved to obtain the coarse particle size of +3 mm flux type steel slag magnetic separation tailings.

[0069] Step (2) The calculated content of coarse-grained flux-type steel slag magnetic separation tailings is 4%, the content of quicklime is 3.6%, the content of coke powder is 2.8%, the basicity is 1.8, the content of MgO is 2.6%, the wet weight of sintering raw materials is 84-86 kg, the moisture content of sintering mixture is 8.4%, and the amount of water added to the disc mixer is 8.4%.

[0070] Step (3) The quicklime and magnesia lime calculated and weighed in step (2) are fed into a disc mixer and a drum granulator to mix and granulate the sintered raw materials, and water is added to obtain a sintered mixed material.

[0071] The sintered mixture obtained in Example 5 has a particle size of +3 mm accounting for 58.73%.

[0072] Step (4) The sintered mixture was placed in a sintering cup covered with 2.8 kg of base material, the material layer height was controlled to be 680 mm, and sintering was ignited at a fan speed of 1850 r / min to obtain sintered ore.

[0073] The permeability index of the sintered material layer obtained in Example 5 is between 268 and 305 m·(kPa·h) -1 The sintered ore yield is 77.62% and the sintering cup utilization coefficient is 1.69 t·h -1 ·m -2 The drum strength of the sintered ore is 64.05%, and the FeO content of the sintered ore is 9.02%.

[0074] Comparative Example 1 Compared with Example 1, the difference is that in step (2), no coarse-grained flux-type steel slag magnetic separation tailings are added to the sintering raw materials, and other operations and parameters are the same as those in Example 1; The results are as follows: the sintered mixture obtained in step (3) has a particle size of +3 mm accounting for 60.47%.

[0075] The permeability index of the sintered material layer obtained in step (4) is between 281 and 329 m·(kPa·h) -1 The sintered ore yield is 76.10% and the sintering cup utilization coefficient is 1.68 t·h -1 ·m -2The drum strength of the sintered ore is 63.05%, and the FeO content of the sintered ore is 8.55%.

[0076] Comparative Example 2 Compared with Example 2, the difference is that the magnetic separation tailings of -3 mm coarse-grained steel slag are obtained in step (1), and the other operations and parameters are the same as those in Example 2; The results are as follows: the sintered mixture obtained in step (3) has a particle size of +3 mm accounting for 57.88%.

[0077] The permeability index of the sintered material layer obtained in step (4) is between 245 and 272 m·(kPa·h) -1 The sintered ore yield is 78.87% and the sintering cup utilization coefficient is 1.73 t·h -1 ·m -2 The drum strength of the sintered ore is 62.23%, and the FeO content of the sintered ore reaches 8.98%.

[0078] Comparative Example 3 Compared with Example 3, the difference is that in step (1), the flux-type steel slag magnetic separation tailings are not mixed, and other operations and parameters are the same as those in Example 3; The results are as follows: the sintered mixture obtained in step (3) has a particle size of +3 mm accounting for 57.44%.

[0079] The permeability index of the sintered material layer obtained in step (4) is between 289 and 323 m·(kPa·h) -1 The sintered ore yield is 77.13%, and the sintering cup utilization coefficient is 1.73 t·h -1 ·m -2 The drum strength of the sintered ore is 61.23%, and the FeO content of the sintered ore reaches 8.85%.

[0080] Comparative Example 4 Compared with Example 4, the difference is that in step (1), the flux-type steel slag magnetic separation tailings are not screened, and other operations and parameters are the same as those in Example 4; The results are as follows: the sintered mixture obtained in step (3) has a particle size of +3 mm accounting for 55.31%.

[0081] The permeability index of the sintered material layer obtained in step (4) is between 260 and 291 m·(kPa·h) -1 The sintered ore yield is 76.62% and the sintering cup utilization coefficient is 1.71 t·h -1 ·m -2 The drum strength of the sintered ore is 61.60%, and the FeO content of the sintered ore reaches 9.12%.

[0082] Comparative Example 5 Compared with Example 5, the difference is that the basicity of the sintering raw material in step (2) is 1.65, and the other operations and parameters are the same as those in Example 5; The results are as follows: the sintered mixture obtained in step (3) has a particle size of +3 mm accounting for 55.74%.

[0083] The permeability index of the sintered material layer obtained in step (4) is between 260 and 294 m·(kPa·h) -1 The sintered ore yield is 77.64%, and the sintering cup utilization coefficient is 1.73 t·h -1 ·m -2 The drum strength of the sintered ore is 61.57%, and the FeO content of the sintered ore reaches 9.07%.

[0084] Table 3 Performance of sintered ore of Examples and Comparative Examples

[0085] As can be seen from Table 3, the comparison results of Example 1 and Comparative Example 1 show that the use of flux-type steel slag magnetic separation tailings for sintering production has both advantages and disadvantages on the sintering process, and the sintered ore yield, sintering cup utilization coefficient and drum strength are all enhanced. The use of flux-type steel slag magnetic separation tailings for sintering production can achieve its high-value utilization. The comparison results of Example 2 and Comparative Example 2 show that the experimental effects of +3mm coarse-grained steel slag magnetic separation tailings for sintering production and -3mm fine-grained steel slag magnetic separation tailings have their own advantages and disadvantages. Among them, the coarse-grained steel slag magnetic separation tailings have higher sintering drum strength, breaking the view that steel slag in the 3~5 mm particle size range cannot replace flux and also reduces the strength of sintered ore in the method for sintering the converter steel slag tailings in Patent Publication No. CN116656890A, which realizes the high-value utilization of coarse-grained flux-type steel slag magnetic separation tailings. The comparison results of Example 3 and Comparative Example 3 show that mixing the steel slag magnetic separation tailings is a necessary measure to ensure the strength of the sintered ore drum and cannot be omitted. The comparison results of Example 4 and Comparative Example 4 show that although the use of fine-grained and coarse-grained steel slag magnetic separation tailings in sintering production will not have much impact on the quality of sintered ore, not screening the steel slag magnetic separation tailings and directly using them in sintering production will have a significant negative impact on the drum strength, and the screening treatment of the steel slag magnetic separation tailings cannot be omitted. The comparison results of Example 5 and Comparative Example 5 show that coarse-grained flux-type steel slag magnetic separation tailings are only suitable for the production of high-basicity sintered ore, and the basicity of the steel slag magnetic separation tailings itself determines its upper limit of the ratio.

[0086] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for using coarse-grained flux-type steel slag magnetic separation tailings in iron ore sintering, characterized in that: The steps include: S1: Mixing and screening the flux type steel slag magnetic separation tailings to obtain coarse particle size flux type steel slag magnetic separation tailings; S2: Calculate the amount of water to be added based on the proportion of coarse-grained flux-type steel slag magnetic separation tailings, iron-containing raw materials, flux and solid fuel to obtain the required amount of sintering raw materials; S3: mixing and granulating the sintering raw materials after quicklime and magnesian lime digestion according to the said proportion of ingredients to obtain a sintering mixture; S4: sintering the sintered mixture with exhaust air to obtain sintered ore; Among them, the flux-type steel slag magnetic separation tailings contain 30%~40% CaO, 10%~15% SiO2, 10%~15% MgO, 5%~10% Al2O3, 10%~15% TFe, 8%~10% FeO, among which the burn loss of the flux-type steel slag magnetic separation tailings is 1%~4%; the coarse particle size of the coarse particle flux-type steel slag magnetic separation tailings is +3 mm; The content of coarse-grained flux-type steel slag magnetic separation tailings in the sintering raw materials is 2%~4%; the content of solid fuel in the sintering raw materials is 2.7%~3.2%; and the basicity of the sintering raw materials is 1.7~2.

2. The method for using the coarse-grained flux-type steel slag magnetic separation tailings in iron ore sintering according to claim 1, characterized in that: In step S1, the mixing process adopts the stacking method, the stacking amount is 30-40 kg, and the stacking times are 3-4 times; the screening process adopts Standard sieve manual screening, screening time is 2~3 min.

3. The method for using the coarse-grained flux-type steel slag magnetic separation tailings in iron ore sintering according to claim 1, characterized in that: In step S1, the +5 mm particle size accounts for 50% to 60% of the coarse-grained flux-type steel slag magnetic separation tailings.

4. The method for using the coarse-grained flux-type steel slag magnetic separation tailings in iron ore sintering according to claim 1, characterized in that: In step S2, the iron-containing raw material is at least one of powder ore, sintered fine powder, pelletizing fine powder, iron oxide filings, iron-containing dust and sintered return ore, the particle size of +3 mm accounts for 25%~28%, and the particle size of -0.5 mm accounts for 40%~44%; the TFe content of the iron-containing raw material is 58%~60%, and the proportion of sintered return ore is 20%~22%.

5. The method for using the coarse-grained flux-type steel slag magnetic separation tailings in iron ore sintering according to claim 1, characterized in that: In step S2, the flux is at least one of quicklime, magnesian lime, limestone powder and dolomite powder, the proportion of -3 mm particle size in quicklime is 98%~99.5%, the proportion of -3 mm particle size in magnesian lime is 95%~98%, the proportion of -3 mm particle size in limestone powder is 75%~80%, and the proportion of -3 mm particle size in dolomite powder is 75%~80%; wherein, the CaO content of quicklime is 78%~82%, the burn loss is 9.5%~10.5%, and the activity is 310~320 mL; the CaO content of magnesian lime is 55%~59%, the MgO content is 30%~33%, the burn loss is 7%~8%, and the activity is 250~260 mL; the fixed carbon content of coke powder is 81%~84%, and the ash content is 14%~15%.

6. The method for using the coarse-grained flux-type steel slag magnetic separation tailings in iron ore sintering according to claim 1, characterized in that: In step S2, the solid fuel is coke powder, and the -3 mm particle size accounts for 90% to 93%; the fixed carbon content of the coke powder is 81% to 84%, and the ash content is 14% to 15%.

7. The method for using the coarse-grained flux-type steel slag magnetic separation tailings in iron ore sintering according to claim 1, characterized in that: In step S2, the basicity of the sintering raw material is 1.7-1.9, the CaO content in the sintering raw material is 3.4%-3.9%, the MgO content in the sintering raw material is 2.5%-2.8%, and the solid fuel content is 2.8%-3.1%.

8. The method for using the coarse-grained flux-type steel slag magnetic separation tailings in iron ore sintering according to claim 1, characterized in that: In step S3, the molar ratio of CaO to digestion water in the sintering raw material is 1:2, and the digestion time is 5 min.

9. The method for using the coarse-grained flux-type steel slag magnetic separation tailings in iron ore sintering according to claim 1, characterized in that: In step S3, the water content of the sintered mixture is 8.4%~9%; the mixing granulation equipment includes a disc mixer and a drum granulator; wherein, the filling rate of the disc mixer is 18%~20%, the rotation speed is 15 r / min, and the mixing time is 180 s; the filling rate of the drum granulator is 10%~12%, the rotation speed is 12 r / min, and the mixing time is 300 s.

10. The method for using the coarse-grained flux-type steel slag magnetic separation tailings in iron ore sintering according to claim 1, characterized in that: In step S4, the sintering ignition temperature is 1100~1150 ℃, and the ignition time is 90 s; the particle size of the base material for sintering is 10~20 mm, and the amount of base material is 2.8~3.1 kg; the material layer height is 660~720 mm; and the exhaust fan speed is 1800~2000 r / min.

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