Preparation method of low-manganese low-sulfur high-purity steel

Abstract

The invention relates to the technical field of ferrous metallurgy and material forming, particularly discloses a preparation method of low-manganese low-sulfur high-purity steel, and aims to produce the low-manganese low-sulfur high-purity steel, and the background is that impurity elements such as manganese and sulfur in ultra-low carbon steel are difficult to remove in the prior art, so that the use performance of the steel is influenced. According to the method, common high-manganese molten iron is adopted, and the low-manganese, low-sulfur and high-conductivity cathode flat steel is produced through converter smelting, LF and RH double refining, billet continuous casting and rolling. The molten iron desulfurizer is a specific mixture, converter smelting is performed by two-time slagging, a blowing method is improved, large-scale production is performed after small-batch tests, the supply capacity is formed, the product performance meets the user requirements, and a high-quality material is provided for reducing power consumption and carbon emission in the electrolytic aluminum industry.

Description

Technical Field

[0001] The invention relates to the technical field of iron and steel metallurgy and material forming, and in particular to a method for preparing low-manganese, low-sulfur and high-purity steel. Background Art

[0002] With the development of modern industry, steel has become more widely used. Cathode flat steel is a must-use material in the electrolytic aluminum industry. The electrolytic aluminum industry is a large energy consumer. In the working environment of the aluminum electrolytic cell, the cathode flat steel is required to have stable conductivity. The cathode flat steel needs to withstand high temperature, highly corrosive electrolyte and electric current for a long time. Highly conductive cathode flat steel should have extremely low resistivity to reduce the loss of electricity during use. Improving the conductivity of cathode flat steel is the best way to reduce energy consumption, reduce costs and reduce carbon emissions. This requires improving the purity of cathode flat steel and reducing impurity elements and non-metallic inclusions in cathode flat steel.

[0003] The carbon, manganese and sulfur contents in cathode flat steel are the main impurity elements that affect the conductivity of cathode flat steel. At present, the commonly used materials in the electrolytic aluminum industry are low-carbon, low-manganese cathode flat steels with a carbon content of less than 0.06w% and a manganese content of less than 0.20w%. However, the existing process cannot simultaneously reduce the manganese and sulfur contents in cathode flat steel, resulting in high resistivity of cathode flat steel, high power consumption and carbon emissions. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing low-manganese, low-sulfur and high-purity steel to solve the problem that the existing process cannot simultaneously reduce the manganese and sulfur contents in the cathode flat steel, thereby resulting in high resistivity of the cathode flat steel, high power consumption and high carbon emissions.

[0005] To achieve the above object, the basic scheme provided by the present invention is: a method for preparing low-manganese, low-sulfur and high-purity steel, comprising the following steps: Composition of smelting finished product: C content is 0.001-0.0020w%, Si content is ≤0.003w%, Mn content is 0.012-0.020w%, P content is ≤0.008w%, S content is ≤0.007w%, Al content is 0.003-0.012w%, Cu content is 0.010-0.020w%, Cr content is 0.012-0.020w%, Ni content is ≤0.010w%, N content is ≤0.0030w%, and the rest is iron and unavoidable impurities; S1. Desulfurize the molten iron from the blast furnace by KR desulfurization method. The desulfurizer is a mixture of active lime and fluorite. The activity of the active lime is greater than 330ml / 4N-HCl. The amount of desulfurizer added is 7-8kg per ton of molten iron. The molten iron before and after desulfurization is deslagging. The deslagging standard is that the molten iron liquid surface is completely exposed. S2. Add 30-34 tons of scrap steel into the converter, and pour in 90-92 tons of desulfurized molten iron for the first oxygen blowing smelting. The height of the oxygen blowing lance head from the liquid surface is 1.6-1.7 meters, the Mach number of the oxygen lance outlet is 1.9-2.0, the maximum impact depth of oxygen on the molten pool is 45-50% of the molten pool depth, the blowing time is 3.8-4.2 minutes, and after the blowing is completed, the slag is poured; S3. After slag pouring is completed, active lime slag is added according to the silicon content in the converter, and then 0.6-0.63t ferrosilicon and 10-15t scrap steel are added to the converter for the second oxygen blowing smelting. The height of the oxygen blowing gun head from the liquid surface is 1.3-1.4m, the oxygen gun outlet Mach number is 1.9-2.0, the maximum impact depth of oxygen on the molten pool is 45-50% of the molten pool depth, and the blowing time is 3.5-4min. After the blowing is completed, steel is tapped; S4, sending the molten steel to the LF furnace for refining, adding 200Kg of active lime and 80Kg of oxidized pellets mainly composed of iron oxide, the oxygen content of the molten steel is 580-650PPm, the temperature of the molten steel is 1615-1630℃, argon is blown from the bottom of the ladle, and the stirring time is 2-3min; S5. The molten steel is transported to the RH process for vacuum treatment. Under the premise that the molten steel does not splash, forced oxygen blowing is performed for 3 to 6 minutes through a three-stage steam vacuum pump for decarburization and demanganese. After the vacuum is exhausted to the limit, rapid decarburization is performed under low vacuum for 6 to 13 minutes; S6. After decarburization and demanganese removal, a composite deoxidizer is added to the ladle top slag; S7, injecting molten steel into the tundish, and then flowing into the crystallizer through the tundish water inlet, after the molten steel forms a shell of a certain thickness in the crystallizer, the billet drawing operation is performed at a finished product drawing speed of 0.8 to 1.2 m / min; S8. When the billet reaches the designed cutting length, the finished product is cut horizontally using a rail-type flame cutting vehicle, and the cutting width is less than 6mm; S9. The cut steel billets are loaded into a furnace for rolling. The specifications of the finished cathode flat steel are 160mm×230mm×2230mm. The starting rolling temperature is 1195~1215℃, and the final rolling temperature is 860~868℃.

[0006] The beneficial effects of the present invention are as follows: the present invention adopts ordinary high manganese molten iron, undergoes molten iron desulfurization pretreatment, top and bottom combined blowing converter smelting, LF and RH double refining, slab continuous casting, cutting and rolling and other processes, and achieves a manganese content of less than 0.025w% by controlling the converter bottom blowing stirring intensity, the end oxygen activity of the molten steel and the like, and uses a specific desulfurizer and process to make the sulfur content of the molten iron entering the furnace less than 0.01w%, and accurately controls the parameters of the converter smelting to inhibit the return of manganese, further optimizes the composition and purity of the molten steel in the refining process, and strictly controls the temperature of continuous casting, cutting and rolling to prepare high-conductivity cathode flat steel, thereby reducing the resistivity of the cathode flat steel and reducing power consumption.

[0007] Option 2: This is the preferred basic option. In S1, the composition of molten iron: carbon content 4.2-4.9w%, silicon content 0.30-0.70w%, manganese content 0.35-0.65w%, phosphorus content ≤0.12w%, sulfur content 0.040-0.055w%, molten iron temperature greater than 1300℃; scrap steel quality requirements: carbon content 0.05-0.35w%, manganese content 0.25-0.35w%, phosphorus content 0.008-0.018w%, sulfur content 0.005-0.012w%, chromium content not more than 0.10w%, nickel content not more than 0.05w%, copper content not more than 0.008w%; clarifying the molten iron composition and scrap steel quality requirements to ensure that the content of each element in the molten iron and scrap steel is within a certain range is conducive to controlling the quality of cathode flat steel.

[0008] Scheme three is the preferred basic scheme. In S1, the composition of the desulfurizer is: active lime content 88w%, fluorite content 12w%, wherein the composition of fluorite is: CaF2 content 75-80w%, SiO2 content 7-10w%, CaCO3 content less than 8w%, and the rest is FeO3 and unavoidable impurities; the composition of the desulfurizer is determined to facilitate reducing the sulfur content in the molten iron so that the sulfur content of the molten iron entering the furnace is less than 0.01w%.

[0009] Scheme 4 is the preferred basic scheme. In S2, during the slag pouring process, it is prohibited to blow nitrogen and argon into the bottom of the converter for stirring, so as to prevent MnO in the slag from being reduced to Mn and returning to the molten steel.

[0010] Scheme 5 is the preferred option of the basic scheme. In S3, the ratio of the silicon content in the converter to the amount of active lime slag added is 1:1.2. Through the ratio of 1:1.2, the pH value and the redox environment in the furnace can be adjusted, the impurity content in the molten steel can be reduced, and the quality of the molten steel can be improved.

[0011] Option six is ​​the preferred basic option. In S4, the main components of the oxidized pellets are: 80w% of continuous casting billet iron oxide scale and 20w% of light-burned dolomite binder. They are evenly stirred by adding water, and then pressed into ellipsoidal pellets with a particle size of 20 to 30 mm, and then naturally air-dried; this is convenient for adjusting the composition of molten steel and removing impurities during the LF furnace refining process, using the continuous casting billet iron oxide scale as the main component.

[0012] Scheme 7: This is the preferred basic scheme. In S5, the minimum vacuum degree is 75-100 Pa, and the circulation flow rate of RH treatment is 78-80 m³ / min, which is convenient for rapid decarburization and demanganeseization.

[0013] Scheme 8, which is the preferred basic scheme, in S5, after decarburization is completed, pure aluminum is added to the vacuum tank to reduce the oxygen content in the molten steel to 15-20 PPm; this is to increase the molten steel temperature at the end of the RH treatment, and the molten steel is not completely precipitated and deoxidized. After adding aluminum for deoxidation, the oxygen content in the molten steel is controlled at 15-20 PPm, reducing the Al content in the molten steel. 2 O 3 The amount and content of inclusions can improve the purity of the material.

[0014] Option nine, which is the preferred basic option, in S6, the components of the composite deoxidizer are: aluminum particle content is 22-28w%, calcium carbonate content is 35-45w%, alumina content is 22-28w%, and light-burned dolomite powder content is less than 10w%.

[0015] Scheme 10, which is a preferred embodiment of Scheme 9, the preparation method of the composite deoxidizer comprises the following steps: Step 1: First, cut the aluminum wire with a diameter of 5 mm into aluminum particles with a length of 5 to 6 mm; Step 2: fully mix aluminum particles, calcium carbonate, aluminum oxide and light-burned dolomite powder; Step 3: Put the fully mixed raw materials into a blender and stir, add an appropriate amount of water, and stir for 13 to 15 minutes; Step 4: After the stirring is completed, the stirred raw materials are put into a ball press to roll and form high-aluminum slag ball particles with a particle size of 20 to 40 mm; Step 5: Air-dry the high-aluminum slag ball particles naturally. The moisture content of the high-aluminum slag ball particles is not more than 0.5w%, which is convenient for ladle slag reforming, deoxidation and removal of inclusions. DETAILED DESCRIPTION

[0016] The present invention is further described in detail below through specific embodiments: A method for preparing low-manganese, low-sulfur and high-purity steel comprises the following steps: Composition of smelting finished product: C content is 0.0016w%, Si content is 0.01w%, Mn content is 0.013w%, P content is 0.005w%, S content is 0.005w%, Al content is 0.004w%, Cu content is 0.012w%, Cr content is 0.015w%, Ni content is 0.008w%, N content is 0.0020w%, and the rest is iron and unavoidable impurities; S1. The molten iron from the blast furnace is desulfurized by the KR desulfurization method. The composition of the molten iron is as follows: carbon content 4.5w%, silicon content 0.40w%, manganese content 0.50w%, phosphorus content 0.12w%, sulfur content 0.050w%, and the molten iron temperature is 1365℃; the quality requirements of scrap steel are as follows: carbon content 0.20w%, manganese content 0.30w%, phosphorus content 0.010w%, sulfur content 0.008w%, chromium content 0.10w%, nickel content 0.05w%, and copper content 0.008w%. The desulfurizer is a mixture of active lime and fluorite. The activity of the active lime is greater than 330ml / 4N-HCl. The composition of the desulfurizer is as follows: active lime content 88w%, fluorite content 12w%, wherein the composition of fluorite is: CaF 2 Content 80w%,SiO 2 Content 10w%, CaCO 3 The content is 8w%, and the rest is FeO 3 As well as unavoidable impurities, the amount of desulfurizer added is 7kg per ton of molten iron, the sulfur content in the molten iron before entering the converter is 0.01w%, the amount of top slag in the molten iron tank is 0.4kg / t, and the molten iron before and after desulfurization is slag-scraped, and the slag-scraping standard is that the molten iron liquid surface is completely exposed; S2. Add 30t scrap steel into the converter and pour in 90t desulfurized molten iron for the first oxygen blowing smelting. 2 The affinity of Mn is lower than that of Si. In the early stage of converter smelting, Si is completely oxidized first, and then Mn is oxidized in a short time to form MnO·SiO 2 , the CaO in the furnace is continuously dissolved, and the reaction formula is as follows: (MnO·SiO 2 )+2CaO=(2CaO·SiO 2)+(MnO). Since Mn can be oxidized to generate MnO, MnO is in a free state when dissolved in slag and is easily reduced. As the furnace temperature continues to rise, MnO is reduced. The reaction process at this time is: (MnO)+[C]=[Mn]+{CO}, (MnO)+[Fe]=[Mn]+(FeO). In the smelting of low-manganese, low-sulfur and high-conductivity steel, it is necessary to inhibit MnO in the slag from being reduced to Mn and then entering the molten steel. Therefore, the distance between the oxygen blowing gun head and the liquid surface is controlled. The height is 1.6m, which reduces the impact depth of the molten pool and inhibits the rapid heating of the converter. The Mach number of the oxygen lance outlet is 1.9. The maximum impact depth of oxygen on the molten pool is 48% of the molten pool depth, which ensures the stability of the jet, increases the impact area of ​​the molten pool, increases the slag-melting speed and inhibits the slag from drying out. The blowing time is 4min. After the blowing is completed, the slag is poured. During the slag pouring process, it is forbidden to blow nitrogen and argon to the bottom of the converter for stirring. The binary basicity of the slag at the end of the first blowing is CaO / SiO 2 is 1.2, the composition of molten steel before slag discharge from the converter: carbon content is 3.0w%, the converter removes Si to 0.15w%, manganese content is 0.05w%, and sulfur content is 0.005w; S3. After slag pouring, active lime slag is added according to the silicon content in the converter. The ratio of the silicon content in the converter to the amount of active lime slag added is 1:1.2. Then 0.62t of ferrosilicon and 12t of scrap steel are added to the converter for the second oxygen blowing smelting. The height of the oxygen blowing gun head from the liquid surface is 1.3m, the Mach number of the oxygen gun outlet is 2.0, the maximum impact depth of oxygen on the molten pool is 50% of the molten pool depth, the blowing time is 4min, and the binary basicity of the converter terminal slag is CaO / SiO 2 The oxygen content of the molten steel at the converter end point is 650PPm. After blowing, steel is tapped. During the converter tapping process, it is strictly forbidden to add any kind of deoxidizer into the ladle, and the molten steel in the ladle is not stirred by bottom blowing argon. S4, sending the molten steel to the LF furnace for refining, adding 200Kg of active lime and 80Kg of oxidized pellets mainly composed of iron oxide, the main components of the oxidized pellets are: 80w% of continuous casting billet oxide scale, 20w% of light-burned dolomite binder, which is stirred evenly by adding water, and then pressed into ellipsoidal pellets with a particle size of 25mm, and then naturally air-dried for use. The slag at the end of refining is transparent and light black, the oxygen content of the molten steel is 600PPm, the temperature of the molten steel is 1630℃, argon is blown at the bottom of the ladle, and the stirring time is 3min. The composition of the molten steel at the end of the LF furnace is: manganese content is 0.025w%, carbon content is 0.030w%, phosphorus content is 0.012w%, sulfur content is 0.007w%, and the binary basicity of the slag is CaO / SiO 2 is 3.8, the iron oxide FeO in the ladle slag and Fe 2 O 3 The sum is 11w%, Al 2 O3 The content is 14w%; S5. The molten steel is transported to the RH process for vacuum treatment. Under the premise that the molten steel does not splash, forced oxygen blowing is carried out for 5 minutes through a 7000kPa three-stage steam vacuum pump for decarburization and demanganese. The circulation flow rate of the RH treatment is 79m³ / min. After the vacuum reaches the limit, the minimum vacuum degree is 90Pa. Rapid decarburization is carried out for 13 minutes under low vacuum degree. The carbon-oxygen reaction rate reaches the highest value. As the carbon content in the molten steel decreases, the CO concentration gradually decreases. After about 15 minutes, the CO volume fraction decreases to below 1%, and the carbon-oxygen reaction basically reaches equilibrium. After decarburization, the oxygen content of the molten steel is 350PPm. Pure aluminum is added to the vacuum tank to reduce the Al content in the molten steel. 2 O 3 The amount and content of inclusions, improve the purity of the material, reduce the oxygen content in the molten steel to 18PPm, and the RH molten steel endpoint temperature is 1625℃; S6. After decarburization and demanganese removal, a composite deoxidizer is added to the ladle top slag. The components of the composite deoxidizer are: 25w% aluminum particles, 40w% calcium carbonate, 25w% aluminum oxide, and 10w% light-burned dolomite powder. The preparation method of the composite deoxidizer comprises the following steps: Step 1: First, cut the aluminum wire with a diameter of 5 mm into aluminum particles with a length of 5 mm; Step 2: fully mix aluminum particles, calcium carbonate, aluminum oxide and light-burned dolomite powder; Step 3: Put the fully mixed raw materials into a blender and stir, add an appropriate amount of water, and stir for 15 minutes; Step 4: After the stirring is completed, the stirred raw materials are put into a ball press to roll and form high-aluminum slag ball particles with a particle size of 30 mm; Step 5: Air-dry the high-aluminum slag ball particles naturally, and the moisture content of the high-aluminum slag ball particles is 0.4w; S7, injecting molten steel into the tundish, and then flowing into the crystallizer through the tundish water inlet, after the molten steel forms a shell of a certain thickness in the crystallizer, the billet drawing operation is performed at a finished product drawing speed of 1.0 m / min; S8. When the billet reaches the designed cutting length, the finished product is cut horizontally using a rail-type flame cutting vehicle, with a slit width of 4 mm; S9. The cut steel billets are loaded into a furnace for rolling. The specifications of the finished cathode flat steel are 160mm×230mm×2230mm. The starting rolling temperature is 1200℃ and the final rolling temperature is 865℃.

[0017] The above is only an embodiment of the present invention, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing low manganese, low sulfur and high purity steel, characterized in that: The following steps are involved: Composition of smelting finished product: C content is 0.001-0.0020w%, Si content is ≤0.003w%, Mn content is 0.012-0.020w%, P content is ≤0.008w%, S content is ≤0.007w%, Al content is 0.003-0.012w%, Cu content is 0.010-0.020w%, Cr content is 0.012-0.020w%, Ni content is ≤0.010w%, N content is ≤0.0030w%, and the rest is iron and unavoidable impurities; S1. Desulfurize the molten iron from the blast furnace by KR desulfurization method. The desulfurizer is a mixture of active lime and fluorite. The activity of the active lime is greater than 330ml / 4N-HCl. The amount of desulfurizer added is 7-8kg per ton of molten iron. The molten iron before and after desulfurization is deslagging. The deslagging standard is that the molten iron liquid surface is completely exposed. S2. Add 30-34 tons of scrap steel into the converter, and pour in 90-92 tons of desulfurized molten iron for the first oxygen blowing smelting. The height of the oxygen blowing lance head from the liquid surface is 1.6-1.7 meters, the Mach number of the oxygen lance outlet is 1.9-2.0, the maximum impact depth of oxygen on the molten pool is 45-50% of the molten pool depth, the blowing time is 3.8-4.2 minutes, and after the blowing is completed, the slag is poured; S3. After slag pouring is completed, active lime slag is added according to the silicon content in the converter, and then 0.6-0.63t ferrosilicon and 10-15t scrap steel are added to the converter for the second oxygen blowing smelting. The height of the oxygen blowing gun head from the liquid surface is 1.3-1.4m, the oxygen gun outlet Mach number is 1.9-2.0, the maximum impact depth of oxygen on the molten pool is 45-50% of the molten pool depth, and the blowing time is 3.5-4min. After the blowing is completed, steel is tapped; S4, sending the molten steel to the LF furnace for refining, adding 200Kg of active lime and 80Kg of oxidized pellets mainly composed of iron oxide, the oxygen content of the molten steel is 580-650PPm, the temperature of the molten steel is 1615-1630℃, argon is blown from the bottom of the ladle, and the stirring time is 2-3min; S5. The molten steel is transported to the RH process for vacuum treatment. Under the premise that the molten steel does not splash, forced oxygen blowing is performed for 3 to 6 minutes through a three-stage steam vacuum pump for decarburization and demanganese. After the vacuum is exhausted to the limit, rapid decarburization is performed under low vacuum for 6 to 13 minutes; S6. After decarburization and demanganese removal, a composite deoxidizer is added to the ladle top slag; S7, injecting molten steel into the tundish, and then flowing into the crystallizer through the tundish water inlet, after the molten steel forms a shell of a certain thickness in the crystallizer, the billet drawing operation is performed at a finished product drawing speed of 0.8 to 1.2 m / min; S8. When the billet reaches the designed cutting length, the finished product is cut horizontally using a rail-type flame cutting vehicle, and the cutting width is less than 6mm; S9. The cut steel billets are loaded into a furnace for rolling. The specifications of the finished cathode flat steel are 160mm×230mm×2230mm. The starting rolling temperature is 1195~1215℃, and the final rolling temperature is 860~868℃.

2. The method for preparing low-manganese, low-sulfur and high-purity steel according to claim 1, characterized in that: In S1, the composition of molten iron: carbon content 4.2~4.9w%, silicon content 0.30~0.70w%, manganese content 0.35~0.65w%, phosphorus content ≤0.12w%, sulfur content 0.040~0.055w%, molten iron temperature is greater than 1300℃; scrap steel quality requirements: carbon content 0.05~0.35w%, manganese content 0.25~0.35w%, phosphorus content 0.008~0.018w%, sulfur content 0.005~0.012w%, chromium content not more than 0.10w%, nickel content not more than 0.05w%, copper content not more than 0.008w%.

3. The method for preparing low manganese, low sulfur and high purity steel according to claim 1, characterized in that: In S1, the composition of the desulfurizer is: active lime content is 88w%, fluorite content is 12w%, wherein the composition of fluorite is: CaF2 content is 75-80w%, SiO2 content is 7-10w%, CaCO3 content is less than 8w%, and the rest is FeO3 and unavoidable impurities.

4. The method for preparing low-manganese, low-sulfur and high-purity steel according to claim 1, characterized in that: In S2, during the slag pouring process, it is prohibited to blow nitrogen or argon into the bottom of the converter for stirring.

5. The method for preparing low manganese, low sulfur and high purity steel according to claim 1, characterized in that: In S3, the ratio of the silicon content in the converter to the amount of active lime slag added is 1:1.

2.

6. The method for preparing low manganese, low sulfur and high purity steel according to claim 1, characterized in that: In S4, the main components of the oxidized pellets are: 80w% of continuous casting billet oxide scale, 20w% of light-burned dolomite binder, which are stirred evenly by adding water, and then pressed into ellipsoidal pellets with a particle size of 20-30mm, and then naturally air-dried, and the moisture content is not more than 0.5w%.

7. The method for preparing low-manganese, low-sulfur and high-purity steel according to claim 1, characterized in that: In S5, the minimum vacuum degree is 75-100 Pa, and the circulation flow rate of RH treatment is 78-80 m³ / min.

8. The method for preparing low manganese, low sulfur and high purity steel according to claim 1, characterized in that: In S5, after decarburization is completed, pure aluminum is added to the vacuum tank to reduce the oxygen content in the molten steel to 15-20 PPm.

9. The method for preparing low manganese, low sulfur and high purity steel according to claim 1, characterized in that: In S6, the components of the composite deoxidizer are: aluminum particle content is 22-28w%, calcium carbonate content is 35-45w%, aluminum oxide content is 22-28w%, and light-burned dolomite powder content is less than 10w%.

10. The method for preparing low-manganese, low-sulfur and high-purity steel according to claim 9, characterized in that: The preparation method of the composite deoxidizer comprises the following steps: Step 1: First, cut the aluminum wire with a diameter of 5 mm into aluminum particles with a length of 5 to 6 mm; Step 2: fully mix aluminum particles, calcium carbonate, aluminum oxide and light-burned dolomite powder; Step 3: Put the fully mixed raw materials into a blender and stir, add an appropriate amount of water, and stir for 13 to 15 minutes; Step 4: After the stirring is completed, the stirred raw materials are put into a ball press to roll and form high-aluminum slag ball particles with a particle size of 20 to 40 mm; Step 5: Air-dry the high-aluminum slag ball particles naturally, and the moisture content in the high-aluminum slag ball is not more than 0.5w%.