Active dephosphorizing agent based on converter dust and cutting slag and preparation method thereof

Abstract

The application discloses an active dephosphorization agent based on converter dust and cutting slag and a preparation method thereof, and the active dephosphorization agent is prepared from the following components in percentage by weight: converter dust: 50wt%-60wt%, cutting slag: 38.2wt%-49.2wt% and active additive: 0.8wt%-1.8wt%. The application realizes high-value resource utilization of solid waste, reduces the production cost of the dephosphorization agent, improves the dephosphorization efficiency and stability, and provides an economically feasible technical scheme for green transformation of the steel industry by reasonably designing the raw material composition of the active dephosphorization agent, selecting the converter dust, the cutting slag and the rare earth additive as raw materials, and combining the optimized process to prepare the active dephosphorization agent.

Description

Technical Field

[0001] This invention relates to the field of steelmaking waste recycling technology, and more specifically, to an active dephosphorizing agent based on converter dust and cutting slag and its preparation method. Background Technology

[0002] As a fundamental industry, the steel industry generates a large amount of solid waste such as converter dust and cutting slag during production. The annual output of such solid waste can reach hundreds of millions of tons, which has become a major pain point for the industry's green development. From a development trend perspective, the disposal of steelmaking solid waste is shifting from extensive stockpiling to refined and high-value utilization, and the constraints on the comprehensive utilization rate of solid waste are becoming increasingly stringent.

[0003] Currently, most solid waste is disposed of through open-air dumping or landfilling, which not only occupies a large amount of valuable land resources but also poses significant environmental risks: heavy metals contained in converter dust and sludge can easily seep in with rainwater, polluting the soil and groundwater; dust generated from cutting slag is dispersed by wind, exacerbating air pollution and seriously threatening the ecological environment and human health. Furthermore, the harmless disposal of this type of solid waste requires high costs, placing a heavy economic burden on enterprises, and the valuable components such as iron and calcium it contains are not effectively utilized, resulting in serious resource waste. Summary of the Invention

[0004] This invention addresses the problems of extensive and wasteful disposal of steelmaking solid waste (converter dust and cutting slag) and overcomes the shortcomings of existing dephosphorizing agents, such as high preparation cost, low activity, and small phosphorus capacity. It provides an active dephosphorizing agent based on converter dust and cutting slag and its preparation method. By synergistically utilizing the component advantages of converter dust, cutting slag, and rare earth additives, and combining optimized processes to prepare active dephosphorizing agents, this invention achieves high-value resource utilization of solid waste, reduces the production cost of dephosphorizing agents, and improves dephosphorization efficiency and stability, providing an economically feasible technical solution for the green transformation of the steel industry.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] An active dephosphorizing agent based on converter dust and cutting slag, wherein the raw materials for preparing the active dephosphorizing agent include the following components by weight percentage: converter dust: 50wt%~60wt%, cutting slag: 38.2wt%~49.2wt%, and active additives: 0.8wt%~1.8wt%.

[0007] Optionally, the cutting slag is high-calcium cutting slag produced in the continuous casting process and / or hot rolling process; Optionally, the active additive is a rare earth oxide.

[0008] Optionally, the converter dust and sludge, calculated as 100% by total mass, shall have TFe ≥ 50 wt% and SiO2 ≤ 8 wt%.

[0009] Optionally, the cutting slag, based on a total mass percentage of 100%, has the following composition: TFe ≥ 50 wt%, CaO ≥ 15 wt%, and SiO2 ≤ 10 wt%.

[0010] Optionally, the active ingredient is La2O3 and / or CeO2.

[0011] Optionally, the active additive has a particle size ≤20μm and a specific surface area ≥150m². 2 / g.

[0012] Optionally, the alkalinity of the active dephosphorizing agent is 1.5 to 3.

[0013] This invention also discloses a method for preparing an active dephosphorizing agent based on converter dust and cutting slag as described above, comprising the following steps: S1. Raw material pretreatment: The converter dust and sludge are dried to a moisture content of ≤1.5wt% to obtain pretreated converter dust and sludge; the cutting slag is crushed to a particle size of ≤0.8mm, then finely ground and sieved through a 200-mesh sieve to obtain fine cutting slag powder. S2. Batching and mixing: According to the raw material ratio, the pretreated converter dust, cutting slag powder and active additives are mixed to obtain a mixture. S3. Low-temperature roasting activation: The mixture is roasted under a nitrogen atmosphere at 220~280℃ to obtain the roasted material; S4. Mechanical activation: The calcined material is ball-milled to obtain dephosphorizing agent powder; S5. Binder-free sintering and pressing: After pressing the dephosphorizing agent powder into shape, sinter it at 450~550℃ in a nitrogen atmosphere, and after cooling to room temperature, obtain the active dephosphorizing agent.

[0014] Optionally, in step S1, the drying temperature is 110~130℃.

[0015] Optionally, in step S2, the mixing speed is 80~120 r / min, and the mixing time is 15~20 min.

[0016] Optionally, in step S3, the calcination time is 25-35 minutes; and the purity of the nitrogen atmosphere is ≥99.9%.

[0017] Optionally, in step S4, the ball milling speed is 400~480 r / min, the ball milling time is 40~55 min, and the ball-to-material ratio is 8~12:1; the particle size of the dephosphorizing agent powder is 12~20 μm.

[0018] Optionally, in step S5, the pressing pressure is 16~19MPa; the sintering time is 35~45min; and the purity of the nitrogen atmosphere is ≥99.9%.

[0019] Implementing the embodiments of the present invention will have the following beneficial effects: This invention rationally designs the raw material composition of the active dephosphorizing agent, selecting converter dust, cutting slag, and rare earth additives as raw materials. In a specific ratio system, iron-containing solid waste and lime can generate calcium ferrite with good slag-forming and dephosphorizing capabilities during sintering. Furthermore, this raw material ratio can increase the alkalinity of the active dephosphorizing agent, which is beneficial to the dephosphorizing reaction in the converter. Simultaneously, the presence of lime helps improve the high-temperature strength performance of the dephosphorizing agent. Specific effects are as follows: (1) In this invention, low-temperature roasting is used to decompose carbonate impurities in the mixture, while inhibiting the oxidation of FeO in converter dust.

[0020] (2) In this invention, FeO in converter dust reacts with CaO and SiO2 in cutting slag to generate a low-melting-point composite oxide phase of calcium iron olivine (CaFe2SiO6), which serves as a natural binder phase to achieve intergranular bonding of the block billet, thus avoiding the potential harm to the cleanliness of the molten steel caused by adding binders.

[0021] (3) In this invention, the natural advantages of high iron and high calcium components in steelmaking solid waste are utilized, and rare earth additives and composite activation process are combined to prepare a dephosphorizing agent with high activity, large phosphorus capacity and strong stability, and the dephosphorization efficiency is significantly improved. Detailed Implementation

[0022] The present invention will be further described below with reference to specific embodiments, but this does not limit the present invention in any way.

[0023] Example 1 The raw materials for preparing the active dephosphorizing agent in this embodiment include the following components by weight percentage: converter dust: 52wt%, continuous casting cutting slag: 47wt%, and La2O3 micro powder additive (particle size 18μm, specific surface area 155m²). 2 / g): 1%.

[0024] The composition of converter dust and continuous casting cutting slag is shown in Table 1 below.

[0025] Table 1

[0026] The preparation method of the active dephosphorizing agent in this embodiment includes the following steps: S1. The converter dust is dried at 110℃ to a moisture content of ≤1.5wt% to obtain pretreated converter dust; the continuous casting cutting slag is processed by jaw crusher to a particle size of ≤0.8mm, and then subjected to planetary fine grinding and 200-mesh sieve to obtain fine powder of cutting slag.

[0027] S2. According to the raw material ratio, the pretreated converter dust, cutting slag powder and La2O3 micro powder additive are put into the shaft mixer for mixing. The mixing speed is 80 r / min and the mixing time is 20 min to obtain the mixture.

[0028] S3. Place the mixture in a tube furnace with a protective atmosphere of high-purity nitrogen with a purity of ≥99.9%, and calcine it at 220℃ for 35 minutes to obtain the calcined material.

[0029] S4. The calcined material is fed into a planetary ball mill for ball milling. The ball milling speed is 400 r / min, the ball milling time is 55 min, and the ball-to-material ratio is 10:1 to obtain dephosphorizing agent powder with a particle size of 12 μm.

[0030] S5. After pressing the dephosphorizing agent powder into shape under a pressure of 16MPa, sinter it at 550℃ for 35min in a nitrogen atmosphere with a purity of ≥99.9%, and then cool it to room temperature to obtain the active dephosphorizing agent.

[0031] The active dephosphorizing agent prepared by this method has an alkalinity of 1.8 and an in-situ generated CaFe2SiO6 calcium-iron composite active phase content of 25.2%. The phosphorus content of the molten steel is reduced from the initial 0.038% to 0.031%. Compared with the traditional quicklime dephosphorizing agent, the dephosphorization rate of this embodiment is 89.6%, which is 28% higher and the raw material cost is reduced by 23%.

[0032] Example 2 The raw materials for preparing the active dephosphorizing agent in this embodiment include the following components by weight percentage: converter dust: 55wt%, continuous casting cutting slag: 43.8wt%, and La2O3 micro powder additive (particle size 17μm, specific surface area 160m²). 2 / g): 1.2%.

[0033] The composition of converter dust and continuous casting cutting slag is shown in Table 2 below.

[0034] Table 2

[0035] The preparation method of the active dephosphorizing agent in this embodiment includes the following steps: S1. The converter dust is dried at 120℃ to a moisture content of ≤1.5wt% to obtain pretreated converter dust; the continuous casting cutting slag is processed by jaw crusher to a particle size of ≤0.8mm, and then subjected to planetary fine grinding and 200-mesh sieve to obtain fine cutting slag powder.

[0036] S2. According to the raw material ratio, the pretreated converter dust, cutting slag powder and La2O3 micro powder additive are put into the shaft mixer for mixing. The mixing speed is 100r / min and the mixing time is 17min to obtain the mixture.

[0037] S3. Place the mixture in a tube furnace with a protective atmosphere of high-purity nitrogen with a purity of ≥99.9%, and calcine it at 250℃ for 30 minutes to obtain the calcined material.

[0038] S4. The calcined material is fed into a planetary ball mill for ball milling. The ball milling speed is 440 r / min, the ball milling time is 50 min, and the ball-to-material ratio is 10:1 to obtain dephosphorizing agent powder with a particle size of 14 μm.

[0039] S5. After pressing the dephosphorizing agent powder into shape under a pressure of 17MPa, sinter it at 500℃ for 40min in a nitrogen atmosphere with a purity of ≥99.9%, and then cool it to room temperature to obtain the active dephosphorizing agent.

[0040] The active dephosphorizing agent prepared by this method has an alkalinity of 2.2 and an in-situ generated CaFe2SiO6 calcium-iron composite active phase content of 27.5%. The phosphorus content of the molten steel is reduced from the initial 0.033% to 0.029%. Compared with the traditional quicklime dephosphorizing agent, the dephosphorization rate of this embodiment is 86.8%, which is 24% higher and the raw material cost is reduced by 20%.

[0041] Example 3 The raw materials for preparing the active dephosphorizing agent in this embodiment include the following components by weight percentage: converter dust: 60wt%, continuous casting cutting slag: 38.6wt%, and CeO2 micro powder additive (particle size 19μm, specific surface area 165m²). 2 / g): 1.4%.

[0042] The composition of converter dust and continuous casting cutting slag is shown in Table 3 below.

[0043] Table 3

[0044] The preparation method of the active dephosphorizing agent in this embodiment includes the following steps: S1. The converter dust is dried at 130℃ to a moisture content of ≤1.5wt% to obtain pretreated converter dust; the continuous casting cutting slag is processed by jaw crusher to a particle size of ≤0.8mm, and then subjected to planetary fine grinding and 200-mesh sieve to obtain fine powder of cutting slag.

[0045] S2. According to the raw material ratio, the pretreated converter dust, cutting slag fine powder and La2O3 micro powder additive are put into the shaft mixer for mixing. The mixing speed is 120r / min and the mixing time is 15min to obtain the mixture.

[0046] S3. Place the mixture in a tube furnace with a protective atmosphere of high-purity nitrogen with a purity of ≥99.9%, and calcine it at 280℃ for 25 minutes to obtain the calcined material.

[0047] S4. The calcined material is fed into a planetary ball mill for ball milling. The ball milling speed is 480 r / min, the ball milling time is 40 min, and the ball-to-material ratio is 10:1 to obtain dephosphorizing agent powder with a particle size of 13 μm.

[0048] S5. After pressing the dephosphorizing agent powder into shape under a pressure of 19MPa, sinter it at 450℃ for 45min in a nitrogen atmosphere with a purity of ≥99.9%, and then cool it to room temperature to obtain the active dephosphorizing agent.

[0049] The active dephosphorizing agent prepared by this method has an alkalinity of 2.5 and an in-situ generated CaFe2SiO6 calcium-iron composite active phase content of 28.1%. The phosphorus content of the molten steel is reduced from the initial 0.035% to 0.03%. Compared with the traditional quicklime dephosphorizing agent, the dephosphorization rate of this embodiment is 88.2%, which is 26% higher and the raw material cost is reduced by 22%.

[0050] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. An active dephosphorizing agent based on converter dust and cutting slag, characterized in that, The raw materials for preparing the active dephosphorizing agent include the following components by weight percentage: Converter dust and sludge: 50wt%~60wt%, cutting slag: 38.2wt%~49.2wt%, and active additives: 0.8wt%~1.8wt%.

2. The active dephosphorizing agent based on converter dust and cutting slag according to claim 1, characterized in that, The cutting slag is high-calcium cutting slag produced by the continuous casting process and / or hot rolling process; The active additive is a rare earth oxide.

3. The active dephosphorizing agent based on converter dust and cutting slag according to claim 1, characterized in that, The converter dust, calculated as a 100% total mass percentage, contains TFe ≥ 50 wt% and SiO2 ≤ 8 wt%. The cutting slag, based on a total mass percentage of 100%, has the following composition: TFe ≥ 50 wt%, CaO ≥ 15 wt%, and SiO2 ≤ 10 wt%. The active additive is La2O3 and / or CeO2; The active additive has a particle size ≤20μm and a specific surface area ≥150m². 2 / g.

4. The active dephosphorizing agent based on converter dust and cutting slag according to claim 1, characterized in that, The alkalinity of the active dephosphorizing agent is 1.5~3.

5. A method for preparing an active dephosphorizing agent based on converter dust and cutting slag as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Dry the converter dust to a moisture content of ≤1.5wt% to obtain pretreated converter dust; crush the cutting slag to a particle size of ≤0.8mm, then grind it and sieve it through a 200-mesh screen to obtain fine cutting slag powder. S2. According to the raw material ratio, the pretreated converter dust, cutting slag powder and active additives are mixed to obtain a mixture. S3. The mixture is calcined under a nitrogen atmosphere at 220~280°C to obtain the calcined material. S4. The calcined material is ball-milled to obtain dephosphorizing agent powder; S5. After pressing the dephosphorizing agent powder into shape, sinter it in a nitrogen atmosphere at 450~550℃, and after cooling to room temperature, obtain the active dephosphorizing agent.

6. The method for preparing the active dephosphorizing agent based on converter dust and cutting slag according to claim 5, characterized in that, In step S1, the drying temperature is 110~130℃.

7. The method for preparing the active dephosphorizing agent based on converter dust and cutting slag according to claim 5, characterized in that, In step S2, the mixing speed is 80~120 r / min, and the mixing time is 15~20 min.

8. The method for preparing the active dephosphorizing agent based on converter dust and cutting slag according to claim 5, characterized in that, In step S3, the calcination time is 25-35 minutes; the purity of the nitrogen atmosphere is ≥99.9%.

9. The method for preparing the active dephosphorizing agent based on converter dust and cutting slag according to claim 5, characterized in that, In step S4, the ball milling speed is 400~480 r / min, the ball milling time is 40~55 min, and the ball-to-material ratio is 8~12:1; the particle size of the dephosphorizing agent powder is 12~20 μm.

10. The method for preparing the active dephosphorizing agent based on converter dust and cutting slag according to claim 5, characterized in that, In step S5, the pressing pressure is 16~19MPa; the sintering time is 35~45min; and the purity of the nitrogen atmosphere is ≥99.9%.

Images