Method for preparing aluminum slag balls from steel ladle slag

Abstract

The invention provides a method for preparing aluminum slag balls from ladle slag. A method for preparing aluminum slag balls from steel ladle slag comprises the following steps: mixing the steel ladle slag, lime powder and aluminum powder, adding a binder, uniformly mixing to prepare spherical particles, drying, and cooling to obtain the aluminum slag balls, the mass ratio of the steel ladle slag to the lime powder to the aluminum powder is (35-45): (5-15): (35-45), and the steel ladle slag comprises CaO, Al2O3, SiO2, MgO and FeO. The steel ladle slag comprises the following components in parts by mass: 30 to 50 parts of CaO, 25 to 45 parts of Al2O3, less than 10 parts of SiO2, less than 8 parts of MgO and less than 1 part of FeO. By using the aluminum slag ball provided by the invention, the melting point of ladle slag can be effectively reduced, the slagging speed is increased, and the improvement effects of shortening the refining period and improving the efficiency can be achieved.

Description

Technical Field

[0001] The present application relates to the technical field of metallurgy and comprehensive utilization of waste resources, and in particular to a method for preparing aluminum slag balls from ladle slag. Background Art

[0002] With the continuous development of my country's steel industry, my country's crude steel output has exceeded 1 billion tons year after year. The resulting solid waste has also increased, causing certain pollution to the environment. At present, steel production faces severe challenges in environmental protection and energy conservation and emission reduction. The recycling of steelmaking waste has become an issue that needs to be urgently addressed.

[0003] my country produces about 15 million tons of refining waste slag every year, which contains a large amount of CaO, SiO2, Al2O3 and MgO (Modern Metallurgy (Iron and Steel Metallurgy Volume) [M]). If these effective components can be utilized, it will not only improve the recycling rate of LF refining waste slag, but also save resources and shorten the smelting time (Steelmaking, 2015, 31(2): 73-78.). The hot recycling of LF ladle slag can reduce the consumption of slag and electricity in the refining process (Steel Vanadium Titanium, 2020, 41(6): 112-118.).

[0004] During the smelting process of ultra-low carbon steel, a large amount of oxygen is blown into the steel during the decarbonization process in the converter, resulting in a high oxygen content in the steel. Therefore, the molten steel needs to be deoxidized during refining. The commonly used composite deoxidizer is aluminum slag balls.

[0005] Commonly used aluminum slag balls are mainly composed of metal Al, Al2O3, CaO, SiO2 and CaF2. During the production process, they are pressed from raw materials. The advantages are simple production and low cost, but the disadvantages are high melting point, which requires the addition of fluorite to lower the melting point, causing greater pollution to the environment.

[0006] In view of this, this application is hereby filed. Summary of the invention

[0007] The purpose of this application is to provide a method for preparing aluminum slag balls from ladle slag to solve the above technical problems.

[0008] This application adopts the following technical solutions:

[0009] A method for preparing aluminum slag balls from ladle slag, comprising mixing ladle slag, lime powder and aluminum powder, adding a binder and mixing evenly to form spherical particles, drying and cooling to obtain aluminum slag balls;

[0010] The mass ratio of the ladle slag, the lime powder and the aluminum powder is (35-45): (5-15): (35-45), and the ladle slag includes CaO, Al2O3, SiO2, MgO and FeO.

[0011] Preferably, the ladle slag comprises the following components by mass fraction:

[0012]

[0013] Preferably, the ladle slag further comprises S and H2O, the mass fraction of S in the ladle slag is less than 0.1 parts, and the mass fraction of H2O in the ladle slag is less than 0.2 parts.

[0014] Preferably, the lime powder comprises CaO and SiO2, and the mass of CaO accounts for no less than 95% of the mass of the lime powder.

[0015] Preferably, the mass fraction of Al in the aluminum powder is not less than 95 parts, the mass fraction of the impurity Cu is not more than 1 part, and the mass fraction of Si is not more than 3 parts.

[0016] Preferably, the particle sizes of the ladle slag, the lime powder and the aluminum powder are all 0.1 mm to 0.5 mm.

[0017] Preferably, the particle size of the spherical particles is 10 mm to 20 mm.

[0018] The aluminum slag balls are obtained by the method for preparing aluminum slag balls from ladle slag.

[0019] The above-mentioned aluminum slag balls are used in steel smelting. The aluminum slag balls are used in the converter to RH process. The adding methods include: all of them are added when the converter taps steel; or all of them are added when the RH taps steel; or they are added in two batches when the converter taps steel and the RH.

[0020] Preferably, the amount of aluminum slag balls added is 1.5-2.5 kg / ton of steel.

[0021] Compared with the prior art, the beneficial effects of this application include:

[0022] 1. The aluminum slag balls of the present application can effectively reduce the melting point of ladle slag, increase the slag melting speed, and improve the refining cycle and efficiency. Compared with patent 200510094825.5, the present patent uses refining waste slag (pre-melted slag) instead of raw materials (aluminum powder, limestone powder, etc.) to mix and press into balls. Compared with mixed slag, pre-melted slag usually has a lower melting point, which is conducive to the rapid melting of aluminum slag balls and enhances the fluidity of slag.

[0023] 2. The aluminum slag ball manufacturing process of the present application is simple to operate and can effectively save costs. Its main raw materials are ladle slag, lime powder and aluminum powder. Compared with 200510094824.0, the composition of the aluminum slag ball preparation of the present application is simple, and the raw materials do not need to be pre-melted at high temperature, which can effectively reduce energy loss and reduce costs.

[0024] 3. The aluminum slag ball production process described in this application can effectively solve the problem of recycling of refining waste slag, reduce the stacking of metallurgical solid waste and waste of resources. The content of refining waste slag added in this application is about 40%, which is conducive to the recycling of metallurgical resources. In addition, compared with 201711365341.9, it effectively saves the use of raw materials such as Al2O3, CaCO3 and MgO, and reduces production costs.

[0025] 4. The production of aluminum slag balls described in this application does not require the addition of fluorite, which can reduce pollution to the environment and increase the life of the refractory materials of the ladle. As described in beneficial effect 1, due to the addition of refined waste slag, the slag balls have a lower melting point and a good slag-removing effect. Compared with patent 02138450.9, there is no need to add fluorite, which can effectively avoid the harm of fluoride volatilization to operators. Replacing the production of fluoride-containing aluminum slag balls with the production of aluminum slag balls described in this application can reduce the erosion of the ladle lining and increase the service life of the ladle.

[0026] 5. The production raw materials described in this application do not contain C, which can effectively avoid carbon addition in the ultra-low carbon steel refining process. DETAILED DESCRIPTION

[0027] To make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are described clearly and completely below. If no specific conditions are specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer shall be followed.

[0028] A method for preparing aluminum slag balls from ladle slag comprises mixing ladle slag, lime powder and aluminum powder, adding a binder and mixing evenly to form spherical particles with a particle size of 10 mm to 20 mm, drying, and cooling to obtain aluminum slag balls. The binder may be bentonite or other binders.

[0029] The mass ratio of ladle slag, lime powder and aluminum powder is (35-45):(5-15):(35-45).

[0030] By mass fraction, ladle slag includes the following components:

[0031]

[0032] Example 1

[0033] Weigh the raw materials: 400kg of ladle slag powder, 100kg of lime powder, 400kg of aluminum powder, and 50kg of bentonite. Mix the above raw materials evenly in a blender and press them into balls. After drying and dehydration, put the aluminum slag balls into the silo for refining and slag. The composition of the ladle slag powder: Al2O3 content is 40%, CaO content is 40%, SiO2 content is 8%, MgO content is 5%, and FeO content is 1%. The particle size of the ladle slag powder is less than 0.3mm.

[0034] The aluminum slag balls produced by this application are used for ultra-low carbon steel refining, and the production process is as follows:

[0035] The mass of molten steel in the ladle used in Example 1 is 180t. The top slag is taken from the ladle before the RH ladle slag is modified, and its composition is shown in Table 1. 360kg of aluminum slag balls (added amount 2.0kg / ton steel) are added to the ladle to modify the ladle slag. After modification, the top slag is taken and its composition is measured. The results are shown in Table 1. The FeO content in the modified slag is reduced by 6.9%. The aluminum slag balls melt quickly after addition, and the aluminum slag balls made from the ladle slag slag slag faster. The fluidity of the ladle slag is significantly improved after modification, and the crust is reduced.

[0036] Example 2

[0037] Weigh the following raw materials: 450kg of ladle slag powder, 50kg of lime powder, 350kg of aluminum powder, and 50kg of bentonite. Mix these raw materials thoroughly in a blender and press them into balls. After drying and dehydration, store the prepared aluminum slag balls in a silo for standby use. The chemical composition of the ladle slag powder is: AlO content 35%, CaO content 50%, SiO content 6%, MgO content 6%, FeO content 2%, and its particle size is less than 0.3mm. The aluminum slag balls produced by this application are used for ultra-low carbon steel refining, and the production process is as follows:

[0038] The production process of this embodiment is as follows: Before the RH ladle slag is modified, the top slag is taken out from the ladle and its composition is analyzed (see Table 1). Then, 450 kg of aluminum slag balls (i.e., 2.5 kg of aluminum slag balls are added per ton of steel) are added to the ladle of 180 tons of molten steel to modify the ladle slag. After modification, samples are taken again and the top slag composition is measured. The results are shown in Table 1. The FeO content in the modified slag is reduced by 7.07%. The aluminum slag balls melt rapidly after being added, and the formed ladle slag slags quickly, the fluidity of the slag is significantly improved, and the crusting phenomenon is significantly reduced.

[0039] Example 3

[0040] First, weigh the raw materials: 350kg of ladle slag powder, 150kg of lime powder, 450kg of aluminum powder and 50kg of bentonite. These raw materials are fully mixed in a mixer, then pressed into balls and dried and dehydrated. The prepared aluminum slag balls are stored in a silo for refining and slag. The composition of the ladle slag powder is: AlO content 45%, CaO content 30%, SiO content 9%, MgO content 4%, FeO content 1%, and the particle size is less than 0.3mm.

[0041] The aluminum slag balls are used for refining ultra-low carbon steel. The process is as follows: Before the RH ladle slag is modified, a sample of the top slag of the molten steel is extracted from the ladle for analysis. Its composition is shown in Table 1. 300 kg of aluminum slag balls (about 1.6 kg per ton of steel) are added to the ladle containing 180 tons of molten steel to modify the ladle slag. After the modification is completed, the composition of the top slag sample is analyzed again, and the results show that the FeO content has decreased by 6.28%. After the aluminum slag balls are added, they melt quickly, the slag formation process is accelerated, the fluidity of the slag is significantly improved, and the crusting phenomenon is reduced.

[0042] Comparative Example

[0043] Ordinary aluminum slag balls were used, and the composition thereof was: Al content was 44%, Al2O3 content was 25%, CaO content was 18%, SiO2 content was 2%, MgO content was 2%, and FeO content was 1%. 300 kg of ordinary aluminum slag balls were added to the ladle for ladle slag modification. Compared with the embodiment, the melting time of the aluminum slag balls in the comparative example was significantly longer. Slag samples before and after modification were taken and their components were tested, and the results are shown in Table 1. The FeO content in the modified slag was reduced by 6.46%. The melting time was longer after the aluminum slag balls were added, and more crusts appeared after the ladle slag was modified.

[0044] After RH re-pressurization, samples of Examples 1, 2, 3 and the comparative example were taken and their total oxygen contents were measured. The total oxygen content in the sample of Example 1 was 0.0018%, the total oxygen content in the sample of Example 2 was 0.0019%, the total oxygen content in the sample of Example 3 was 0.0016%, and the total oxygen content in the comparative example sample was 0.0020%, and the total oxygen content of each sample was basically the same.

[0045] Table 1 Slag sample composition (%)

[0046]

[0047] It can be seen that the aluminum slag balls prepared by the present application have the same deoxidation capacity for molten steel and ladle slag as ordinary aluminum slag balls. However, due to its better melting characteristics, the melting speed is fast after adding it in the refining process, and the fluidity of the modified slag is good. It not only improves the slag formation rate, but also completes the better recycling of the refining waste slag, which is conducive to the recycling of metallurgical resources.

[0048] The above are only preferred embodiments of the present application and are not intended to limit the present application. Although the present application has been described in detail above with general descriptions and specific implementations, it is obvious to those skilled in the art that some modifications or improvements may be made to the present application.

Claims

1. A method for preparing aluminum slag balls from ladle slag, characterized in that: The ladle slag, lime powder and aluminum powder are mixed, and then a binder is added and mixed evenly to form spherical particles, which are then dried and cooled to obtain aluminum slag balls; The mass ratio of the ladle slag, the lime powder and the aluminum powder is (35-45): (5-15): (35-45), and the ladle slag includes CaO, Al2O3, SiO2, MgO and FeO.

2. The method for preparing aluminum slag balls from ladle slag according to claim 1, characterized in that: The ladle slag comprises the following components by mass fraction:

3. The method for preparing aluminum slag balls from ladle slag according to claim 1, characterized in that: The ladle slag also includes S and H2O, the mass fraction of S in the ladle slag is less than 0.1 parts, and the mass fraction of H2O in the ladle slag is less than 0.2 parts.

4. The method for preparing aluminum slag balls from ladle slag according to claim 1, characterized in that: The lime powder comprises CaO and SiO2, and the mass of CaO accounts for no less than 95% of the mass of the lime powder.

5. The method for preparing aluminum slag balls from ladle slag according to claim 1, characterized in that: The mass fraction of Al in the aluminum powder is not less than 95 parts, the mass fraction of impurity Cu is not more than 1 part, and the mass fraction of Si is not more than 3 parts.

6. The method for preparing aluminum slag balls from ladle slag according to claim 1, characterized in that: The particle sizes of the ladle slag, the lime powder and the aluminum powder are all 0.1 mm to 0.5 mm.

7. The method for preparing aluminum slag balls from ladle slag according to claim 1, characterized in that: The particle size of the spherical particles is 10 mm to 20 mm.

8. The aluminum slag balls obtained by the method for preparing aluminum slag balls from ladle slag according to any one of claims 1 to 7.

9. The use of the aluminum slag balls according to claim 8 in steelmaking, characterized in that: The aluminum slag balls are used in the process of converter to RH, and the adding methods include: all of them are added when the converter is tapping steel; or all of them are added when the RH is tapping steel; or they are added in two batches when the converter is tapping steel and when the RH is tapping steel.

10. The use according to claim 9, characterized in that: The amount of aluminum slag balls added is 1.5-2.5 kg / ton of steel.

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