High-silicon iron ore pellet as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of metallurgical ironmaking, and discloses a high-silicon iron ore pellet as well as a preparation method and application thereof. The preparation method of the high-silicon iron ore pellets comprises the following steps that S1, high-silicon iron ore, a binder and ferrous nitrate are mixed, hydrogen peroxide is added for pelletizing, and green pellets are obtained; and S2, the green pellets are dried, preheated and roasted, and the high-silicon iron ore pellets are obtained. The preparation method of the high-silicon iron ore pellets is high in process compatibility, the consolidation kinetics of the high-silicon iron ore under the low-temperature condition can be effectively enhanced according to the characteristics of the high-silicon iron ore, and the mechanical strength and metallurgical performance of the pellets are remarkably improved on the premise of not depending on high-temperature or long-time roasting; environment protection and efficient utilization of resources are considered, green low-carbon production of high-quality pellets is achieved, and the method is simple in process, controllable in cost and high in adaptability, has large-scale industrial popularization potential and is expected to promote transformation of the iron and steel industry to the green low-carbon direction.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of metallurgical ironmaking, and discloses high-silicon iron ore pellets as well as a preparation method and application thereof. BACKGROUND

[0002] The steel industry is a basic material industry for the development of the national economy, and is also a key field of energy consumption and carbon emission. Under the strong driving of the strategic goal of "carbon peak and carbon neutrality", it has become an urgent task and core task for the steel industry to promote the transformation towards green and low carbon. In the whole process of steel production, the iron front system (mainly including sintering, pelletizing and coking processes) is a key link of energy consumption and carbon dioxide emission, and has great potential for energy saving and carbon reduction. Among them, pellet is one of the indispensable high-quality furnace charges for modern blast furnace ironmaking, and has the advantages of high grade, good strength, uniform particle size, excellent metallurgical properties and the like. Its production and use are of great significance for optimizing the blast furnace burden structure, improving the ironmaking efficiency, reducing the comprehensive energy consumption and reducing the carbon emission.

[0003] However, the traditional pellet production process generally relies on a high roasting temperature when producing high-strength pellets that meet the requirements of blast furnace smelting. Such high-temperature roasting process not only has huge energy consumption, but also is the main source of carbon emission in the pellet process, which is contrary to the goal of green and low-carbon development of the steel industry. Therefore, significantly reducing the roasting temperature of the pellets, realizing low-temperature roasting under the premise of ensuring the strength of the pellets, has become the core direction of the industry's technical research, and is crucial for reducing the overall energy consumption and carbon emission of the iron front system. The fundamental challenge faced by reducing the roasting temperature is that too low temperature of the thermal system will weaken the driving force and reaction rate of the internal physical and chemical reactions (such as magnetite oxidation, hematite recrystallization, slag phase formation and consolidation) of the pellets, which directly leads to insufficient consolidation, and the mechanical strength (such as compressive strength and drum index) of the produced pellets is difficult to meet the strict requirements of blast furnace smelting. Although, within a certain range, the strength of the pellets can be improved at a lower temperature by prolonging the roasting time, this method will also seriously sacrifice the production efficiency, leading to increased unit energy consumption, reduced equipment utilization and poor economic efficiency, and is difficult to be widely applied in actual production.

[0004] The production and application of high-silicon iron ore further exacerbate this problem. The siliceous gangue (mainly composed of quartz) in its composition has the following problems during roasting: (1) High melting point and low reactivity: Quartz has a very high melting point, and it is difficult to fully participate in the formation of low-temperature effective solidification liquid phase under normal or even higher roasting temperature conditions. At the same time, its chemical inertness is more pronounced in a low-temperature environment, which seriously hinders the effective solidification of the pellets. (2) Crystal transformation and volume effect: Quartz undergoes crystal transformation during heating and cooling, accompanied by significant volume change. This volume change easily induces internal stress in the pellets, which in turn leads to the generation of micro-cracks or even macro-cracks, causing serious damage to the strength of the pellets. (3) Upshift of solidification temperature window: In order to promote the formation of silicate slag phase to encapsulate quartz particles and achieve effective solidification, it is usually necessary to increase the roasting temperature or extend the holding time, which directly conflicts with the goal of low-temperature energy saving and carbon reduction. (4) Difficulty in balancing strength and metallurgical performance: Even if a certain strength is obtained through high temperature or prolonged time, the low-temperature reduction disintegration performance (RDI) of high-silicon pellets is often poor, which seriously affects the smooth production of blast furnaces.

[0005] Therefore, there is an urgent need to develop an innovative process method that can effectively strengthen the solidification kinetics under low-temperature conditions based on the characteristics of high-silicon iron ore, significantly improve the mechanical strength and metallurgical performance of the pellets without relying on high-temperature or long-time roasting, and realize the green and low-carbon production of high-quality pellets. SUMMARY

[0006] The purpose of the present application is to overcome the shortcomings of the prior art and provide a high-silicon iron ore pellet and a preparation method and application thereof.

[0007] To achieve the above-mentioned purpose, the technical solutions adopted by the present application are as follows: In a first aspect, the present application provides a preparation method of a high-silicon iron ore pellet, characterized in that it comprises the following steps: S1, mixing high-silicon iron ore, binder and ferrous nitrate, adding hydrogen peroxide to pelletize, obtaining green pellets; the mass of the ferrous nitrate is 1%-20% of the mass of the high-silicon iron ore; the mass of the hydrogen peroxide is 1%-12% of the mass of the high-silicon iron ore; the mass of the ferrous nitrate is not more than 2 times the mass of the hydrogen peroxide; S2, drying, preheating and roasting the green pellets to obtain the high-silicon iron ore pellets.

[0008] The preparation method of the high-silicon iron ore pellet realizes significant improvement of the strength, reducibility and metallurgical properties of the high-silicon iron ore pellet through a three-stage strengthening mechanism of oxidation-bridging-solidification combined with precise control of process parameters. 2+ The hydrogen peroxide has strong oxidizing property, which on one hand strengthens the oxidation of magnetite in the pellet, eliminates the risk of volume expansion caused by unoxidized phases (such as residual magnetite); on the other hand, catalyzes the oxidation of Fe in silicate minerals, reduces the interference of low-valence iron on the reduction reaction, strengthens the crystallization of iron ore, improves the degree of intercrystallization, and thus makes the high-crystallinity iron ore more easily form continuous metallic iron nuclei in the reduction process, improving the reduction kinetics performance. Meanwhile, the ferrous nitrate as an additive is oxidized to hematite nanoparticles by H2O2 in the initial stage of roasting, which uniformly fills the gaps between high-silicon iron ore particles to form a bridging structure of "iron ore-hematite-iron ore"; later in the high-temperature roasting process, these hematite formed from ferrous nitrate will fuse and recrystallize with high-silicon iron ore to form new iron ore grains, thereby strengthening the intercrystallization degree of iron ore and further improving the compressive strength, reduction performance and anti-pulverization performance of the pellet. In addition, the preparation method of the high-silicon iron ore pellet has strong process compatibility and is green and environmentally friendly, which can effectively strengthen the solidification kinetics under low-temperature conditions according to the characteristics of high-silicon iron ore, significantly improve the mechanical strength and metallurgical properties of the pellet without relying on high-temperature or long-time roasting, realize green and low-carbon production of high-quality pellets, balance environmental protection and resource efficient utilization, has extremely high application value and development prospect, and has simple process, controllable cost and strong adaptability, which has great potential for large-scale industrialization and is expected to promote the transformation of the steel industry towards green and low-carbon direction.

[0009] As a preferred embodiment of the preparation method of the high-silicon iron ore pellet, the mass of the ferrous nitrate is 3%-10% of the mass of the high-silicon iron ore.

[0010] Preferably, the mass of the ferrous nitrate is one or a range value of two of 3%, 4%, 5%, 6%, 7%, 8%, 9% and 10% of the mass of the high-silicon iron ore.

[0011] As a preferred embodiment of the preparation method of the high-silicon iron ore pellet, the ferrous nitrate is any one of ferrous nitrate powder, ferrous nitrate hydrate and ferrous nitrate aqueous solution (the addition ratio is calculated according to the pure substance of ferrous nitrate).

[0012] As a preferred embodiment of the preparation method of the high-silicon iron ore pellet, the mass of the hydrogen peroxide is 6%-10% of the mass of the high-silicon iron ore.

[0013] Preferably, the mass of the hydrogen peroxide is one or a range value of two of 6%, 7%, 8%, 9% and 10% of the mass of the high-silicon iron ore.

[0014] As a preferred embodiment of the preparation method of the high-silicon iron ore pellets, the mass ratio of the ferrous nitrate and the hydrogen peroxide is (0.3-2):1.

[0015] Preferably, the mass ratio of the ferrous nitrate and the hydrogen peroxide is (1-2):1.

[0016] Further preferably, the mass ratio of the ferrous nitrate and the hydrogen peroxide is 1:1.

[0017] As a preferred embodiment of the preparation method of the high-silicon iron ore pellets, the mass fraction of TFe in the high-silicon iron ore is 60wt%-65wt%, and the mass fraction of SiO2 is 8wt%-15wt%.

[0018] As a preferred embodiment of the preparation method of the high-silicon iron ore pellets, the high-silicon iron ore comprises the following mass percentages of components: TFe 60%-65%, FeO 25%-30%, SiO2 8%-15%, MgO 0.3%-1%, Al2O3 1%-2.5%, CaO 0.2%-1%, K2O 0.03%-0.1%, Na2O 0.5%-1%, S 0.2%-0.5%, and P 0.01%-0.03%.

[0019] As a preferred embodiment of the preparation method of the high-silicon iron ore pellets, the binder comprises at least one of bentonite, sodium silicate, and sodium carboxymethyl cellulose.

[0020] Preferably, the binder is sodium-based bentonite and / or calcium-based bentonite.

[0021] Further preferably, the binder is sodium-based bentonite.

[0022] As a preferred embodiment of the preparation method of the high-silicon iron ore pellets, the mass ratio of the high-silicon iron ore and the binder is (80-100):1.

[0023] As a preferred embodiment of the preparation method of the high-silicon iron ore pellets, the hydrogen peroxide is hydrogen peroxide pure reagent and / or hydrogen peroxide aqueous solution (the addition ratio is calculated according to the hydrogen peroxide pure substance).

[0024] As a preferred embodiment of the preparation method of the high-silicon iron ore pellets, the water content is controlled to be 8%-10% of the total mass of the mixture (the mixture includes the high-silicon iron ore, the binder, the ferrous nitrate, and the hydrogen peroxide) during the balling process.

[0025] Preferably, the water content is 8% of the total mass of the mixture.

[0026] As a preferred embodiment of the preparation method of the high-silicon iron ore pellets, the temperature of the preheating is 900-950℃.

[0027] Preferably, the temperature of the preheating is 920℃.

[0028] As a preferred embodiment of the preparation method of the high-silicon iron ore pellets, the temperature of the roasting is 1200-1260℃, and the time is 15-40min.

[0029] As a preferred embodiment of the preparation method of the high-silicon iron ore pellets, the temperature of the roasting is 1200℃, and the time is 20min.

[0030] In a second aspect, the present application provides the high-silicon iron ore pellets prepared by the preparation method.

[0031] In a third aspect, the present application provides the application of the high-silicon iron ore pellets in blast furnace ironmaking, electric furnace steelmaking, gray cast iron, and ductile cast iron.

[0032] Compared with the prior art, the present application has the following beneficial effects: first, the preparation method of the high-silicon iron ore pellets realizes the significant improvement of the strength, reducibility, and metallurgical properties of the high-silicon iron ore pellets through the synergistic oxidation-bridging effect of ferrous nitrate and hydrogen peroxide and the precise control of process parameters. Second, the preparation method of the high-silicon iron ore pellets can effectively strengthen the solidification kinetics under low-temperature conditions according to the characteristics of high-silicon iron ore, significantly improve the mechanical strength and metallurgical properties of the pellets under the premise of not relying on high-temperature or long-time roasting, and realize the green and low-carbon production of high-quality pellets. In addition, the preparation method of the high-silicon iron ore pellets has strong process compatibility, provides key technical support for the efficient utilization of high-silicon iron ore, has extremely high application value and market prospect, and has simple process, controllable cost, strong adaptability, large-scale industrialization potential, and the potential to promote the transformation of the steel industry to green and low-carbon direction. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The SEN diagrams of the pellets prepared in Comparative Example 1, Comparative Example 6, and Example 1 of the present application; Figure (a) is the pellets of Comparative Example 1, Figure (b) is the pellets of Comparative Example 5, and Figure (c) is the pellets of Example 1. DETAILED DESCRIPTION

[0034] In order to better illustrate the purpose, technical scheme, and advantages of the present application, the present application will be further described below in combination with specific embodiments. Those skilled in the art should understand that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0035] The following is described in connection with specific examples to illustrate the practical effects of the present application scheme.

[0036] The test methods used in the examples are conventional methods unless otherwise specified; the materials, reagents, equipment, etc. used are commercially available unless otherwise specified.

[0037] The chemical composition of the high-silicon iron ore used in the following examples and comparative examples is shown below: Table 1 Chemical composition of high-silicon iron ore (wt%) TFe 62.26 FeO 28.93 SiO2 13.23 MgO 0.56 Al2O3 1.82 CaO 0.50 K2O 0.051 Na2O 0.602 S 0.255 P 0.012 The high-silicon iron ore used in the examples is purchased from Xiangtan Iron and Steel Group Co., Ltd., model De Yuan Concentrate; The sodium-based bentonite used in the examples is purchased from Xiangtan Iron and Steel Group Co., Ltd., model sodium-based modified bentonite P-90.

[0038] Example 1: A high-silicon iron ore pellet is prepared in this example, and the preparation method includes the following steps: (1) 60 g of sodium-based bentonite and 500 g of ferrous nitrate powder are added to 5 kg of high-silicon iron ore and mixed uniformly, and the above-mentioned materials are placed in a disc pelletizer (diameter Ф = 1000 mm, side height h = 250 mm) for pelletizing, the disc pelletizer rotates at a speed of 20 r / min, the disc inclination angle is 45 degrees, and the pelletizing time is 12 min. During the pelletizing process, a hydrogen peroxide aqueous solution with a mass concentration of 70% is sprayed onto the surface of the materials (the addition ratio is calculated based on the pure hydrogen peroxide, so that the mass of pure hydrogen peroxide in the system is 500 g), the pelletizing moisture is controlled at 8 wt%, and the pelletizing time is 12 min. The green pellets with a diameter of 12-15 mm are prepared.

[0039] (2) The drop strength is used as the key index for screening, and the green pellets with a drop strength ≥ 4 times / 0.5 m are selected as qualified products, and the qualified green pellets are placed in a 120℃ oven for drying; the dried pellets are transferred to a preheating device for preheating, the preheating temperature is 920℃, and the preheating time is 10 min; then they are placed in a roasting temperature of 1200℃ for roasting for 20 min, and finally cooled to room temperature to obtain the pellets.

[0040] Example 2: A high-silicon iron ore pellet is prepared in this example, and the difference between the preparation method and Example 1 is that in step (1), the mass of ferrous nitrate powder is 1000 g.

[0041] Example 3: A high-strength pellet is prepared in this example, and the difference between the preparation method and Example 1 is that in step (1), the mass of ferrous nitrate powder is 150 g.

[0042] Example 4: In this example, a high-silicon iron ore pellet was prepared, and the difference between the preparation method and Example 1 is that in step (1), the mass of hydrogen peroxide pure substance in the system is 600g.

[0043] Example 5: In this example, a high-silicon iron ore pellet was prepared, and the difference between the preparation method and Example 1 is that in step (1), the mass of hydrogen peroxide pure substance in the system is 300g.

[0044] Example 6: In this example, a high-silicon iron ore pellet was prepared, and the difference between the preparation method and Example 1 is that in step (1), the mass of ferrous nitrate powder is 100g, and the mass of hydrogen peroxide pure substance in the system is 50g.

[0045] Example 7: In this example, a high-silicon iron ore pellet was prepared, and the difference between the preparation method and Example 1 is that in step (1), the mass of ferrous nitrate powder is 50g, and the mass of hydrogen peroxide pure substance in the system is 50g.

[0046] Example 8: In this example, a high-silicon iron ore pellet was prepared, and the difference between the preparation method and Example 1 is that in step (2), the roasting temperature is 1260℃.

[0047] Example 9: In this example, a high-silicon iron ore pellet was prepared, and the difference between the preparation method and Example 1 is that in step (2), the roasting temperature is 1230℃.

[0048] Comparative Example 1: In this comparative example, a high-silicon iron ore pellet was prepared, and the preparation method includes the following steps: (1) 60g of sodium bentonite was added to 5kg of high-silicon iron ore and mixed uniformly, and the above material was placed in a disc pelletizer (diameter Ф=1000mm, side height h=250mm) for pelletizing, the disc pelletizer speed was 20r / min, the disc inclination was 45 degrees, the pelletizing time was 12min, the pelletizing water content was controlled at 8wt%, and the pelletizing time was 12min, to prepare green balls with a diameter of 12-15mm.

[0049] (2) The falling strength was selected as the key index for screening, and the green balls with falling strength ≥4 times / 0.5m were selected as qualified products, and the qualified green balls were placed in a 120℃ oven for drying; the dried pellets were transferred to a preheating device for preheating, the preheating temperature was 920℃, and the preheating time was 10min; then it was placed at a roasting temperature of 1200℃ for 20min, and finally cooled to room temperature to obtain the pellets.

[0050] Comparative Example 2: The comparative example prepared a high-silicon iron ore pellet, the preparation method of which was different from that of Comparative Example 1 in that in step (2), the roasting temperature was 1300°C.

[0051] Comparative Example 3: The comparative example prepared a high-silicon iron ore pellet, the preparation method of which was different from that of Comparative Example 1 in that in step (1), 200 g of ferrous nitrate powder was added to the mixed materials.

[0052] Comparative Example 4: The comparative example prepared a high-silicon iron ore pellet, the preparation method of which was different from that of Comparative Example 1 in that in step (1), 500 g of ferrous nitrate powder was added to the mixed materials.

[0053] Comparative Example 5: The comparative example prepared a high-silicon iron ore pellet, the preparation method of which was different from that of Example 1 in that in step (1), the mass of the ferrous nitrate powder was 0.

[0054] Comparative Example 6: The comparative example prepared a high-silicon iron ore pellet, the preparation method of which was different from that of Example 6 in that in step (1), the mass of the ferrous nitrate powder was 150 g.

[0055] Comparative Example 7: The comparative example prepared a high-silicon iron ore pellet, the preparation method of which was different from that of Example 1 in that in step (1), the mass of the ferrous nitrate powder was 1200 g.

[0056] Comparative Example 8: The comparative example prepared a high-silicon iron ore pellet, the preparation method of which was different from that of Example 1 in that in step (1), the aqueous hydrogen peroxide solution was replaced with an aqueous potassium permanganate solution of the same concentration (the addition ratio was calculated according to the pure substance of potassium permanganate, so that the mass of the pure substance of potassium permanganate in the system was 500 g).

[0057] Comparative Example 9: The comparative example prepared a high-silicon iron ore pellet, the preparation method of which was different from that of Example 1 in that in step (1), the balling moisture was controlled to be 15 wt%.

[0058] Comparative Example 10: The comparative example prepared a high-silicon iron ore pellet, the preparation method of which was different from that of Example 1 in that in step (1), the balling moisture was controlled to be 5 wt%.

[0059] Comparative Example 11: This comparative example prepared a high-silicon iron ore pellet. The difference between its preparation method and that of Example 1 is that the preheating temperature in step (2) is 850℃.

[0060] Test example: This test case examines the performance of pellets prepared in the example and the comparative example.

[0061] (1) Pellet compressive strength test Testing standard: Based on ISO 4700 standard.

[0062] Test method: Apply axial pressure to the pellets using a pressure testing machine until the pellets rupture, record the maximum pressure value and calculate the compressive strength (the blast furnace requires a compressive strength of not less than 2500N / pellet).

[0063] (2) Reduction of pellets (RI) test Test standard: Based on GB / T13241-91 standard.

[0064] Test method: The reduction degree (RI) of the pellets is calculated by simulating the reduction conditions of a blast furnace using a reduction degree meter. The reduction degree of the pellets is reflected by measuring the weight loss rate of the pellets under specific atmosphere and temperature.

[0065] (3) Pellet Reduction and Powdering Properties (RDI) +3.15 / %)test Testing standard: Based on GB / T13242-2015 standard.

[0066] Test method: A reduction pulverization test apparatus was used to simulate the low-temperature reduction conditions in the upper part of a blast furnace to determine the pulverization rate (RDI) of the reduced pellets. +3.15 (A higher chalking rate means less chalking), reflecting its resistance to chalking.

[0067] (4) The internal mineral phase microstructure of the pellets of Example 1, Comparative Example 1, and Comparative Example 5 was observed using a scanning electron microscope.

[0068] Table 2 Performance test results of pellets from the examples and comparative examples. Sample Pellet compressive strength (N / pellet) RI (%) Reduction disintegration (%) Example 1 4352 72.23 95.21 Example 2 3998 68.77 94.29 Example 3 3423 70.23 94.52 Example 4 4589 73.15 95.29 Example 5 3862 70.22 93.98 Example 6 2698 63.96 95.11 Example 7 2569 64.45 95.32 Example 8 2759 70.39 95.59 Example 9 3423 70.23 94.52 Comparative Example 1 2356 63.21 90.11 Comparative Example 2 2371 61.88 92.18 Comparative Example 3 2125 55.69 85.73 Comparative Example 4 1874 51.26 79.85 Comparative Example 5 3218 73.21 96.52 Comparative Example 6 2453 62.59 91.59 Comparative Example 7 3101 64.32 93.29 Comparative Example 8 2812 70.23 94.12 Comparative Example 9 2736 71.11 92.88 Comparative Example 10 2569 70.12 90.11 Comparative Example 11 2701 68.82 87.29 like Figure 1 As shown, compared with Comparative Example 1 (Figure a) and Comparative Example 5 (Figure b), the pellets of Example 1 of the present invention (Figure c) have a higher degree of iron oxide intercrystallization and a denser internal structure, indicating a higher degree of oxidation. This is because the strong oxidizing property of hydrogen peroxide in the present invention can enhance the oxidation of magnetite inside the pellets and catalyze the oxidation of Fe in silicate minerals. 2+Oxidation, eliminating the risk of volume expansion caused by unoxidized phases (such as residual magnetite); on the other hand, it can also strengthen the crystallization of iron ore, improve the degree of intercrystallization, and thus make it easier for high-crystallinity iron ore to form continuous metal iron nuclei during reduction, thereby improving the reduction kinetics performance. At the same time, ferrous nitrate as an additive is oxidized to hematite nanoparticles by H2O2 at the initial stage of roasting, uniformly distributed in the gap between high-silicon iron ore particles, forming a "iron ore-hematite-iron ore" bridging structure; later, during high-temperature roasting, these hematite formed from ferrous nitrate will fuse and recrystallize with high-silicon iron ore to form new iron ore grains, thereby strengthening the intercrystallization degree of iron ore and further improving the compressive strength, reduction performance, and anti-pulverization performance of the pellets.

[0069] As shown in Table 2, the compressive strength of the pellets of the present application is much higher than the blast furnace standard (≥2500N / pellet), which can withstand the pressure of the column and the friction of the charge in the blast furnace, reducing the damage rate of the charge into the furnace, thereby stabilizing the blast furnace operation and prolonging the service life of the furnace lining. Secondly, the reduction degree of the pellets of the present application is ≥70%, which can significantly increase the diffusion channel of the reducing gas, optimize the pore connectivity, reduce the diffusion resistance of the reducing gas, accelerate the reaction kinetics, thereby reducing the consumption of coke in the blast furnace, reducing CO2 emissions, and meeting the "double carbon" target of the steel industry. In addition, the anti-pulverization performance of the pellets of the present application is strong, and the structural stability is stronger, which can maintain the permeability of the upper layer of the blast furnace, reduce the risk of suspended and collapsed materials, ensure the smooth operation of the blast furnace, and reduce the emission of furnace dust. Therefore, the preparation method of the pellets of the present application provides a large-scale preparation scheme for high-performance pellets for blast furnace ironmaking, which can be widely applied to steel enterprises and short-process electric furnace-blast furnace combined enterprises, and promotes the green and low-carbon transformation of the steel industry.

[0070] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A method for producing high-silica iron ore pellets, characterized by, The method comprises the following steps: S1, mixing high-silicon iron ore, binder and ferrous nitrate, adding hydrogen peroxide to make balls, to obtain green balls; the mass of the ferrous nitrate is 1%-20% of the mass of the high-silicon iron ore; the mass of the hydrogen peroxide is 1%-12% of the mass of the high-silicon iron ore; the mass of the ferrous nitrate is not more than 2 times the mass of the hydrogen peroxide; S2, drying, preheating and roasting the green balls to obtain the high-silicon iron ore pellets.

2. The method of producing high-silica iron ore pellets according to claim 1, characterized by, The mass fraction of TFe in the high-silicon iron ore is 60wt%-65wt%, and the mass fraction of SiO2 is 8wt%-15wt%.

3. The method of producing high-silica iron ore pellets according to claim 1, wherein The binder comprises at least one of bentonite, sodium silicate and sodium carboxymethyl cellulose.

4. The method of producing high-silica iron ore pellets according to claim 1, characterized by, The mass ratio of the high-silicon iron ore to the binder is (80-100):

1.

5. The method of producing high-silica iron ore pellets according to claim 1, wherein The mass of the ferrous nitrate is 3%-10% of the mass of the high-silicon iron ore; the mass of the hydrogen peroxide is 6%-10% of the mass of the high-silicon iron ore.

6. The method of producing high-silica iron ore pellets according to claim 1, wherein The water content is controlled to be 8%-10% of the total mass of the mixture during the ball making process.

7. The method of producing high-silica iron ore pellets according to claim 1, wherein The preheating temperature is 900°C-950°C.

8. The method of producing high-silica iron ore pellets according to claim 1, wherein The roasting temperature is 1200°C-1260°C, and the time is 15min-40min.

9. The high-silicon iron ore pellets prepared by the preparation method of any one of claims 1-8.

10. The application of the high-silicon iron ore pellets of claim 9 in blast furnace ironmaking, electric furnace steelmaking, gray cast iron and ductile cast iron.

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