A casting slag-based refining slag-making agent

Abstract

The invention discloses a casting slag-based refining slag-making agent, which relates to the technical field of steel manufacturing. The components of the refining slag-making agent are: 50-60% of casting slag after magnetic separation, 35-45% of calcium carbonate, 2-3% of industrial salt, and a molding binder of 0.5%-1.5% of the total mass of the main raw materials. The invention realizes the comprehensive utilization of secondary resources, and at the same time improves the purpose of the current situation that lime + fluorite slag is slow and the effect is unstable.

Description

Technical Field

[0001] The invention relates to the field of iron and steel metallurgy, and in particular to a casting slag-based refining slag-making agent. Background Art

[0002] At present, the refining slag system is mainly represented by CaO-Al2O3-based and CaO-SiO2-based. CaO-Al2O3-based slag system has many metallurgical characteristics for off-furnace refining, including: 1) high basicity; 2) strong desulfurization ability; 3) low oxygen potential, which can play a role in diffusion deoxidation; 5) strong absorption capacity of inclusions; 6) fluorine-free or low-fluorine, suitable for fast refining operation and environmental protection requirements. CaO-Al2O3-based slag system can not only be used in off-furnace refining processes such as LF, RH, VAD and VOD, but also as a covering for the intermediate steel liquid in the continuous casting process. In terms of melting point, fluidity, etc., because it has a strong capacity for CaO and Al2O3, a large amount of lime, foaming agent, etc. can be added to form LF refining slag with strong desulfurization ability. Because of the above advantages, the CaO-Al2O3-based refined slag system is widely used in steel smelting, but it also has some problems: 1) The cost is high. In order to ensure the rapid melting slag-forming effect of the CaO-Al2O3-based refined slag system, steel mills generally use pre-melted CaO-Al2O3-based refined slag. The price of such pre-melted refined slag is nearly 3,000 yuan per ton, and it can generally only be used for the production of high-quality, high-value-added products; 2) Simply using high-Al2O3 raw materials such as bauxite to supplement the Al2O3 content in the refined slag has a slightly lower cost, but the melting effect is not good, and slag-forming materials such as fluorite are often required. Considering the pollution of fluorite to the environment and the decreasing mineral reserves, foreign steel metallurgical industries basically no longer or rarely use fluorite, and for this reason, it is expected that relevant policies will be introduced in China to limit or reduce the use of fluorite in the steel metallurgical industry. Therefore, a refining slag-making agent with casting slag as the main material is developed to improve this situation. After refining and slagging, the casting slag has the characteristics of fast melting into slag like pre-melted slag. At the same time, according to the composition of the casting slag, appropriate addition of some components can achieve effective control of the steel grade composition. This kind of refining slag-forming agent has the advantages of fast slag formation (second only to pre-melted slag), low cost (equivalent to the price of lime), and strong desulfurization ability.

[0003] Similar patent technologies mainly include the following:

[0004] CN202111208386 A resource processing method for aluminum-iron alloy metallurgical slag used for steelmaking, discloses a resource processing method for aluminum-iron alloy metallurgical slag, the slag left over from aluminum-iron smelting is subjected to magnetic separation to remove iron, and then the alloy is separated by sorting, and the remaining tailings are added with limestone, coke, etc. to reduce iron, and calcium aluminate slag is obtained at the same time, which is pre-melted slag and can be used as slag for steelmaking and refining. However, its cost is relatively high, and the raw materials are not easy to obtain.

[0005] CN201910228821 A method for controlling the pulverization and recycling of steelmaking refined slag, for the reductive refined slag outside the furnace, a slag system based on CaO-Al2O3 is used in the slag type, and the composition of the refined slag is controlled so that the refined slag contains, by mass percentage, CaO 50%-66%, SiO2 8%-12%, Al2O3 21%-42%, MgO 7.6%-10% and FeO+MnO0.7%-3%; R of the refined slag is ≧4; the refined slag after the control is completed is recycled according to the steel slag cascade utilization process, or recycled in the refining process, and the temperature of the refined slag is not higher than 500 degrees Celsius during the recycling process. Although it can effectively reduce the pulverization of steelmaking refined slag, it is not necessary to add additional modulating substances, which is convenient for its return and utilization, prevents the dust from floating during the transportation process caused by pulverization, and improves the operating environment. By recycling steel slag, the consumption of slag-making materials and slag discharge are reduced, which has high economic and environmental value. It is also a way to recycle casting slag, but this method is relatively simple, and can only use partially reducing slag. It is highly targeted at steel grades and cannot achieve the recycling of casting slag of all calm steel grades. It also has a great impact on on-site operations.

[0006] CN201110192283 A method for producing high-basicity steelmaking refining slag, which is used in the steelmaking furnace refining process, solves the problem of slow hydration of lime powder and melting of added lime blocks. The method includes: crushing and grinding the lime just burned in the lime kiln, putting the ground lime fine powder into a fluidized bed at a temperature of 650-750°C, passing the waste gas and water vapor discharged from the lime kiln burning lime, using the CO2 in the waste gas discharged from the lime kiln burning lime to passivate and waterproof the lime surface, and using water vapor to accelerate the passivation treatment of the lime surface by CO2. Then the passivated lime powder is mixed with the solvent powder, and the wet or dry method is used to form balls and sieve. Although it has the characteristics of high basicity, fast melting speed, good spreadability, low cost and long storage time; it can shorten the refining time outside the steelmaking furnace and improve the S and P removal rate of molten steel in the steelmaking furnace refining process outside the steelmaking furnace; at the same time, it utilizes the CO2 waste gas discharged from the lime kiln burning lime. However, the basicity of the refined slag produced is too high, and the slag components have limited ability to absorb inclusions and the cost is relatively high. Summary of the invention

[0007] The purpose of the present invention is to provide a casting slag-based refining slag-making agent, which realizes the comprehensive utilization of secondary resources and improves the current situation that the lime+fluorite slag is slow and the effect is unstable.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A refining slag-forming agent based on casting slag, the components of the refining slag-forming agent include main raw materials and auxiliary materials, the main raw materials are calculated by mass fraction as follows: 50-60% of casting slag after magnetic separation, 35-45% of calcium carbonate, 2-3% of industrial salt (NaCl), and the auxiliary material is a molding binder, which accounts for 0.5%-1.5% of the total mass of the main raw materials.

[0010] Based on the above technical solution, preferably, the selected casting slag is crushed and then subjected to magnetic separation to remove metallic iron and control FeO within 5%.

[0011] Based on the above technical solution, preferably, the casting slag is a killed steel casting slag, and its composition range is as follows by mass fraction:

[0012] CaO: 35-45%, SiO2: 5-12%, Al2O3: 21-32%, FeO: 2-7%, MgO: 6-10%, and the rest is some metallic iron and impurities.

[0013] Based on the above technical solution, preferably, the particle size of the pulverized casting slag is 0-3 mm.

[0014] Based on the above technical solution, preferably, the molding binder, by mass fraction, has a composition range of: bentonite 40-60%, sodium carboxymethyl cellulose 2%, gluten 10-20%, and cement 20-30%.

[0015] Based on the above technical solution, preferably, the cement is 425 cement.

[0016] Based on the above technical solution, preferably, the preparation method of the refining slag-forming agent comprises the following steps:

[0017] Step 1, dry mixing, mixing the main raw material dry material and stirring for 5-7 minutes to mix well, then adding the auxiliary material forming binder dry material and stirring for 3-5 minutes until uniform, to prepare a dry mixed material;

[0018] Step 2: Use a strong ball press to dry-press the balls to prepare pellets with a size (diameter) of 20-35 mm;

[0019] Step 3: Screening: Use a sieve with a 10 mm mesh to screen the pellets, and select pellets with a particle size greater than 10 mm to prepare a refining slag-making agent.

[0020] The refining slag-forming agent of the present invention is applied to converter steelmaking or refining process. When the refining slag-forming agent is applied to converter steelmaking, the amount of the refining slag-forming agent added is 3-5kg / t steel; when the refining slag-forming agent is applied to the refining process, the amount of the refining slag-forming agent added according to the desulfurization requirements is 3-10kg / t steel.

[0021] The beneficial effects of the present invention are as follows: the casting slag-based refining slag-making agent of the present invention can realize the recovery of casting slag of all killed steel grades, the raw materials are easy to obtain, the comprehensive utilization of secondary resources is realized, the cost is low, the slag-forming condition is good, and at the same time the current situation of slow slag production and unstable effect of lime + fluorite is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the slag slag formation of small platform steel in Example 1.

[0023] Figure 2 This is the slag-forming condition of LF steel slag in Example 1.

[0024] Figure 3 This is the slag slag formation of small platform steel in Example 2.

[0025] Figure 4 This is the slag slag formation of LF steel slag in Example 2.

[0026] Figure 5 This is the slag slag formation of small platform steel in Example 3.

[0027] Figure 6 This is the slag formation of LF steel slag in Example 3. DETAILED DESCRIPTION

[0028] The following non-limiting embodiments may enable a person skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0029] Example 1

[0030] A method for preparing a casting slag-based refining slag-forming agent comprises the following steps:

[0031] (1) The casting slag is selected as a killed steel casting slag, and its composition is:

[0032] CaO: 40%, SiO2: 9%, Al2O3: 37%, FeO: 5%, MgO: 8%, and the rest is some metallic iron and impurities.

[0033] (2) The selected casting slag is crushed and then subjected to magnetic separation to remove metallic iron and control FeO within 5%.

[0034] (3) The components of the refined slag-making agent are: 57% of the casting slag after magnetic separation, 40% of calcium carbonate, 3% of industrial salt (NaCl), and 1% of the total mass of the main raw materials as the molding binder; the components of the molding binder are: 52% of bentonite, 2% of sodium carboxymethyl cellulose, 18% of gluten, and 28% of 425 cement.

[0035] (4) further comprising the following steps:

[0036] Step 1, dry mixing, mixing the main raw material dry material and stirring for 5-7 minutes to mix well, then adding the auxiliary material forming binder dry material and stirring for 3-5 minutes until uniform, to prepare a dry mixed material;

[0037] Step 2: Use a strong ball press to dry-press the balls to prepare pellets with a size of 20-35 mm;

[0038] Step 3: Screening: Use a sieve with a 10 mm mesh to screen the pellets, and select pellets with a particle size greater than 10 mm to prepare a refining slag-making agent.

[0039] Example 2

[0040] A method for preparing a casting slag-based refining slag-forming agent comprises the following steps:

[0041] (1) The casting slag is selected as a killed steel casting slag, and its composition is:

[0042] CaO: 45%, SiO2: 6%, Al2O3 30%, FeO: 7%, MgO: 10%, and the rest are some metallic iron and impurities.

[0043] (2) The selected casting slag is crushed and then subjected to magnetic separation to remove metallic iron and control FeO within 5%.

[0044] (3) The components of the refined slag-making agent are: 52% of the casting slag after magnetic separation, 45% of calcium carbonate, 2% of industrial salt (NaCl), and 1.5% of the total mass of the main raw materials as the molding binder; the components of the molding binder are: 55% of bentonite, 2% of sodium carboxymethyl cellulose, 20% of gluten, and 23% of 425 cement.

[0045] (4) further comprising the following steps:

[0046] Step 1, dry mixing, mixing the main raw material dry material and stirring for 5-7 minutes to mix well, then adding the auxiliary material forming binder dry material and stirring for 3-5 minutes until uniform, to prepare a dry mixed material;

[0047] Step 2: Use a strong ball press to dry-press the balls to prepare pellets with a size of 20-35 mm;

[0048] Step 3: Screening: Use a sieve with a 10 mm mesh to screen the pellets, and select pellets with a particle size greater than 10 mm to prepare a refining slag-making agent.

[0049] Example 3

[0050] After the converter is tapped, 3 kg / t of steel is added to the refining slag-making agent prepared in Example 1, and argon is blown on the small platform for 5 minutes. The steel slag is basically melted and has good spreadability. Figure 1 .

[0051] LF enters the station and adds 4kg / t steel of refining slag-making agent. On-site observation shows that slag is completely removed in 3 minutes. Figure 2 The slagging condition is good and the desulfurization rate is 43.7%.

[0052] Example 4

[0053] After the converter tapped, 4 kg / t of steel was added to the refining slag-making agent prepared in Example 1, and argon was blown on the small platform for 4.5 min. The slag was basically melted and had good spreadability. Figure 3 .

[0054] LF enters the station and adds 5kg / t steel of refining slag-making agent. On-site observation shows that slag is completely removed in 5 minutes. Figure 4 The slagging condition is good and the desulfurization rate is 55.4%.

[0055] Example 5

[0056] After the converter is tapped, 5 kg / t of the refining slag-making agent prepared in Example 1 is added, and argon is blown on the small platform for 5 minutes. The slag is basically melted and has good spreadability. Figure 5 .

[0057] LF enters the station and adds 10kg / t steel of refining slag-making agent. On-site observation shows that slag is completely removed in 8 minutes. Figure 6 The slagging condition is good and the desulfurization rate is 76.7%.

[0058] Example 3-5 Steel composition (mass fraction %, the balance is iron and unavoidable impurities)

[0059]

[0060] For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments with equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention should still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A casting slag-based refining slag-making agent, characterized in that: The components of the refining slag-making agent include main raw materials and auxiliary materials. The main raw materials are calculated by mass fraction as follows: 50-60% of magnetically separated casting slag, 35-45% of calcium carbonate, and 2-3% of industrial salt. The auxiliary material is a molding binder, and the molding binder is 0.5%-1.5% of the total mass of the main raw materials. The casting slag is a killed steel casting slag, and its components are as follows by mass fraction: CaO: 35-45%, SiO2: 5-12%, Al2O3: 21-32%, FeO: 2-7%, MgO: 6-10%, and the rest is metallic iron and impurities; Industrial salt is NaCl.

2. The casting slag-based refining slag-making agent according to claim 1, characterized in that: The casting slag after magnetic separation is free of metallic iron and has FeO controlled within 5%.

3. The casting slag-based refining slag-making agent according to claim 1, characterized in that: The molding binder comprises, by mass fraction, 40-60% bentonite, 2% sodium carboxymethyl cellulose, 10-20% gluten and 20-30% cement.

4. The casting slag-based refining slag-making agent according to claim 1, characterized in that: The particle size of the casting slag is 0-3 mm.

5. The casting slag-based refining slag-making agent according to claim 3, characterized in that: The cement is 425 cement.

6. The casting slag-based refining slag-making agent according to claim 1, characterized in that: The preparation method of the refining slag-forming agent comprises the following steps: Step 1, dry mixing, mixing the main raw material dry material and stirring for 5-7 minutes to mix well, then adding the auxiliary material forming binder dry material and stirring for 3-5 minutes until uniform, to prepare a dry mixed material; Step 2: Use a strong ball press to dry press the pellets to prepare pellets with a specification of 20-35 mm; Step 3: Screening: Use a sieve with a 10 mm mesh to screen the pellets, and select pellets with a particle size greater than 10 mm to prepare a refining slag-making agent.

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