Low-cost and high-efficiency desulfurizer for converter direct-up continuous casting and production process thereof

Abstract

The application discloses a low-cost and high-efficiency desulfurizer for converter straight-up continuous casting and a preparation method, and the raw materials are derived from mineral deep processing and solid waste recycling. Compared with the manganese iron or silicon calcium wire refining desulfurization process and the premelt type preparation process, the use cost is greatly reduced. The composition of the desulfurizer comprises 60-80% of super-low-sulfur metallurgical lime powder, 10-25% of selected aluminum scrap and 10-15% of selected low-sulfur fluorite sand. Each component is prepared through a non-premelt cold forming process and is passivated by 0.3-0.5% of methyl silicone oil, and the product particle size is 5-50 mm. The desulfurizer is added to the bottom of a ladle before converter tapping, and is directly used for continuous casting after argon blowing and stirring. In subsequent application, when the addition amount is 5 kg of the desulfurizer per ton of steel, the sulfur content is reduced from 0.047% to 0.0119%, the desulfurization rate is 74.6%, and the straight-up requirement (S% <= 0.020%) is met.

Description

Technical Field

[0001] This invention relates to a low-cost, high-efficiency desulfurizing agent for converter direct-flow continuous casting and its production process, belonging to the field of steelmaking desulfurizing agents. Background Technology

[0002] Sulfur is one of the harmful elements in steel. Its main hazards are hot brittleness and anisotropy of rolled steel. Therefore, the sulfur content in steel must be strictly limited.

[0003] Currently, both domestic and international converter carbon steelmaking generally employs secondary refining for deep desulfurization of molten steel to ensure that the sulfur content meets the quality requirements of the grade steel before continuous casting. The basic process is as follows: blast furnace → hot metal pretreatment → converter → secondary refining (LF furnace) → continuous casting. Taiyuan Iron & Steel Group's No. 2 steelmaking plant, in order to significantly increase production speed, plans to eliminate the secondary LF furnace refining process and adopt a new process: blast furnace → hot metal pretreatment → converter → continuous casting. This involves directly adding desulfurizing agent and supplementing with silicon-calcium wire for deep desulfurization during the tapping process, followed by argon blowing and stirring, before directly casting. This process has serious drawbacks: high cost, a desulfurization rate of only 9%-40%, and instability, failing to meet the requirements for direct casting.

[0004] To increase steel production and reduce costs, a direct-fired converter continuous casting process is planned for the production of ordinary carbon steel. This requires a cost-effective solution to address the adverse effects of the lack of a secondary refining process (LF furnace refining), achieving a stable desulfurization rate of over 50% in the carbon steel refining process and a target sulfur content below 0.020%, thereby accelerating production. To ensure the target sulfur content, billet quality, and constant casting speed, a highly efficient and low-cost refining desulfurizing agent needs to be developed. Summary of the Invention

[0005] This invention aims to provide a low-cost and high-efficiency desulfurizing agent and its production process for converter direct continuous casting, so as to achieve deep desulfurization of molten steel, solve the adverse effects caused by the lack of secondary refining process (LF furnace refining) at low cost, achieve the direct casting requirement of carbon steel refining desulfurization rate of more than 50% and target sulfur of less than 0.020%, thereby improving production efficiency.

[0006] This invention relates to a high-efficiency desulfurizing agent for converter direct-fired continuous casting and its production process. The raw materials are derived from deep mineral processing and solid waste recycling. The homogenized binder-free cold forming preparation process is adopted, which significantly reduces the cost of use compared with the refining and desulfurization process of ferromanganese or silicon-calcium wire and the pre-melted preparation process.

[0007] The high-efficiency desulfurizer involved in this invention functions as a heat-generating agent, deoxidizer, ultra-low sulfur desulfurization and slag formation agent, and replaces the function of the secondary refining LF furnace, which significantly shortens the steelmaking process and achieves increased production and efficiency.

[0008] This invention relates to the process of adding the product to the bottom of the ladle before tapping from the converter, stirring it with argon, and then directly casting it into the continuous casting process.

[0009] This invention provides a low-cost, high-efficiency desulfurizing agent for direct-fired converter casting, which is prepared from the following raw materials: Ultra-low sulfur metallurgical lime powder 60-80%, aluminum shavings 10-25%, low sulfur fluorite sand 10-15%; The ultra-low sulfur metallurgical lime powder has a sulfur content of S% < 0.010%; the aluminum shavings contain ≥ 70% metallic aluminum and 10%-30% alumina by weight; the low sulfur fluorite sand has a sulfur content of 0.010% ≤ S% ≤ 0.030%.

[0010] This invention provides a production process for the aforementioned low-cost and high-efficiency desulfurizing agent for direct-fired converter casting, comprising the following steps: (1) Obtaining low-sulfur raw materials: Using the Fugu low-sulfur anthracite co-firing and diesel strong oxidation technology, low-sulfur lime raw materials with a sulfur content of less than 0.025% are produced; (2) Deep processing of raw materials: aluminum scrap, ultra-low sulfur metallurgical lime powder and low sulfur fluorite sand are obtained at low cost through off-line selection and impurity removal processes; (3) Product preparation: The obtained raw materials are mixed evenly by mass percentage: 60-80% of ultra-low sulfur metallurgical lime powder, 10-25% of aluminum shavings, and 10-15% of low sulfur fluorite sand. The mixture is fed into a high-pressure roller press by a forced feeder and rolled into strips of 100mm×20mm×10mm. The strips fall naturally into a blade crusher and a granulator for crushing. The qualified particles are screened out to a size of 5-50mm. The unqualified powder is recycled back into the roller press for molding. (4) Product passivation: Weigh 0.3-0.5% of the total mass of the above products with methyl silicone oil, pressurize it through a variable frequency metering pump of 0.1-0.5L / min, and heat it to 80-100℃ through a conveying pipe with a heat tracing cable. Finally, passivate the finished product through an atomizing nozzle to reduce moisture absorption and powdering, ensure product storage time, and solve the powdering defect of non-pre-melted cold forming.

[0011] Specifically, the preparation process is as follows: The preparation process of the selected ultra-low sulfur metallurgical lime powder is as follows: (1) In a 1000T / D rotary kiln for lime production, a strong oxidation technology is used, consisting of 90% Fugu low-sulfur anthracite and 10% diesel fuel, with a coal injection rate of 9200kg / h, an oil injection rate of 0.92kg / h, and a secondary air volume greater than 51000Nm³. 3 Under operating conditions of / h, low-sulfur limestone is calcined at high temperature (1250-1320℃) to produce low-sulfur lime blocks A with a sulfur content of less than 0.025% and a particle size of 10-40mm. (2) 10-40mm low sulfur lime blocks A are crushed by a 0-15mm low speed compound crusher and separated into 5-15mm blocks B and 0-5mm powder C by a closed rolling screen; powder C contains high sulfur content such as kiln skin, slag, and soil, which are used for other purposes, such as sintering. (3) 5-15mm block material B is crushed by a 0-5mm medium-speed compound crusher, and under the action of a cyclone dust collector, 0-1mm ultra-low sulfur metallurgical lime powder (S% < 0.010%) and 1-5mm small block material D are separated; among them, small block material D contains hard kiln skin with high sulfur content, quick-burned lime, miscellaneous stones, etc., and is used for other purposes, such as sintering.

[0012] After the above-mentioned secondary impurity removal pretreatment process, the obtained ultra-low sulfur (S% < 0.010%) metallurgical lime powder can replace common ordinary lime. On the one hand, it reduces the sulfur content brought in by lime, and on the other hand, the high-purity lime can achieve low-cost improvement of alkalinity and sulfur capacity.

[0013] The preparation process of the selected low-sulfur fluorite sand is as follows: (1) After the fluorite ore is crushed by a jaw crusher with a diameter of 0-80mm, it is spread out by a loader and then the silica and vein skin are picked out manually. (2) After stirring and washing, fluorite with high sulfur content is removed from fluorite fabric with 0-80mm fluorite. (3) After the above steps, the fluorite blocks are naturally air-dried, and the sulfur content is reduced from 0.35-0.50% to 0.010-0.030%, the calcium fluoride content is increased from 85-90% to 94-96%, and the moisture content is reduced from more than 5% to less than 1%. (4) Low-moisture fluorite blocks are crushed by a 0-2mm low-speed compound crusher to obtain low-sulfur fluorite sand.

[0014] The main process for preparing the selected aluminum scrap is as follows: primary aluminum slag → crushing → ball milling → closed drum screen screening → aluminum scrap; specifically including the following steps: (1) The aluminum slag is crushed into small pieces of 0-15mm by a 0-15mm jaw crusher; (2) After being ground and separated by an aluminum slag ball mill, the 0-15mm small pieces of material enter a closed rotating screen to separate 2-15mm of selected aluminum chips and 0-2mm of secondary aluminum slag. (3) Secondary aluminum slag is sent to the cement plant to make CA-50 fast-hardening cement raw material.

[0015] In the above-mentioned aluminum shavings preparation process, the entire system is enclosed, equipped with a dust hood, and a cyclone dust collector is configured to ensure the working environment.

[0016] Aluminum slag (primary aluminum slag) is the product of molten slag produced in the electrolytic aluminum or cast aluminum production process after cooling and processing. Its main components are metallic aluminum w(Al) 15% to 40%, aluminum oxide and silicon dioxide, etc.

[0017] Using aluminum scrap (containing ≥70% aluminum and 10%-30% alumina) recovered from primary aluminum slag (containing 15%-40% metallic aluminum and 50%-70% alumina) can achieve the following objectives: ① Metallic aluminum can deoxidize the slag system, providing a prerequisite for deep desulfurization; ② The oxidation process of metallic aluminum is exothermic, which can increase the temperature of molten steel and the desulfurization rate; ③ It forms a low-melting-point C12A7 (calcium heptaaluminate) with the slag system, improving desulfurization kinetics.

[0018] The above-mentioned desulfurizer production process replaces the pre-melting process with a homogenized, binder-free cold forming preparation process and a passivation treatment process, achieving cost reduction and efficiency improvement in the preparation process. The main process flow is as follows: various raw materials → homogenization treatment → forced feeding → high-pressure rolling forming → blade crusher crushing → granulation forming by granulator → passivation to prevent deterioration; specifically including the following steps: (1) The raw materials are packed according to the principle of the most compact packing, with small-particle low-sulfur fluorite sand and aluminum shavings as aggregates, and ultra-low sulfur metallurgical lime powder as filler. The ratio of aggregate to powder is controlled to be 1 / 4 to 2 / 3. After being homogenized by a mixer, the raw materials are carried into the forced feeding silo (intermediate silo) by a bucket elevator. (2) Under the action of the screw forced feeder, the volume of the above loose material is compressed to 1 / 4 of the original volume after passing through the forced feeder; (3) The compressed material is fed into the roller table of the high pressure roller press by a forced feeder and rolled into strips of 100mm×20mm×10mm under a pressure of 15-25MPa. (4) The strip-shaped material falls naturally into the blade crusher for crushing and the 0-50mm cage pelletizer for pelletizing; (5) The crushed and granulated material is screened by a multi-layer shaking table vibrating screen to separate qualified particles of 5-50mm. Unqualified material (<5mm) is recycled back into the roller press for molding. (6) Passivation treatment: Methyl silicone oil is delivered by a variable frequency metering pump and heated to 80-100°C through a conveying pipe with a heat tracing. The finished material is then passivated by an atomizing nozzle to reduce moisture absorption and powdering, ensure product storage time, and solve the powdering defect of non-pre-melted cold forming.

[0019] This invention provides a method for using the aforementioned low-cost and high-efficiency desulfurizing agent for direct-fired converter casting, the specific steps of which are as follows: (1) Before tapping steel from the converter, the material is discharged through the high-level silo at the top of the furnace, weighed by the metering belt, and added to the bottom of the ladle; (2) During the tapping process of the converter, the molten steel impacts and forms the first stirring desulfurization; (3) Stirring with Ar for 5-8 minutes to form a second deep desulfurization process; (4) After the sample is tested and found to be qualified, it is hoisted to the continuous casting station by the overhead crane.

[0020] All percentages mentioned in this invention are mass percentages.

[0021] The beneficial effects of this invention are: (1) The raw materials are derived from mineral deep processing and solid waste recycling. The homogenized binder-free cold forming preparation process is adopted. Compared with the refining, desulfurization and pre-melting process of manganese iron or silicon calcium wire, the production and use costs are greatly reduced.

[0022] (2) The present invention relates to a product whose functional components are heating, deoxidation, ultra-low sulfur desulfurization and slag formation, which replace the function of the secondary refining LF furnace, greatly shorten the steelmaking process, and achieve increased production and efficiency.

[0023] (3) This invention relates to the addition of the product to the bottom of the ladle before the steel is tapped from the converter, followed by argon blowing and stirring before continuous casting; when the amount of desulfurizing agent added is 5 kg / ton of steel, the sulfur content is reduced from 0.047% to 0.0119%, and the desulfurization rate is 74.6%; when the amount of desulfurizing agent added is 2.5 kg / ton of steel, the average sulfur content is reduced from 0.0295% to 0.0131%, and the desulfurization rate is 54.9%; this invention uses a low-cost desulfurizing agent to solve the adverse effects caused by the lack of secondary refining process (LF furnace refining), and achieves a stable desulfurization rate of carbon steel molten steel greater than 50%, with the target sulfur meeting the direct casting requirement of S≤0.020%, thereby improving the production pace. Attached Figure Description

[0024] Figure 1 This is a process flow diagram for preparing ultra-low sulfur metallurgical lime powder according to the present invention. Figure 2 A process flow diagram for preparing selected low-sulfur fluorite sand according to the present invention; Figure 3 This is a process flow diagram for preparing selected aluminum chips according to the present invention; Figure 4 The production process flow diagram for preparing the low-cost and high-efficiency desulfurizing agent of this invention is shown in the figure. Detailed Implementation

[0025] The present invention will be further illustrated by the following embodiments, but is not limited to the following embodiments. Example 1

[0026] A production process for preparing a low-cost, high-efficiency desulfurizing agent is described below: (1) According to Figure 1 , 2The production process yields selected ultra-low sulfur metallurgical lime powder, selected aluminum shavings, and selected low-sulfur fluorite sand. The main physicochemical properties are shown in Table 1 below. Table 1

[0027] (2) Design a high-efficiency desulfurizer formula 1, the formula composition is: 60% of selected ultra-low sulfur metallurgical lime powder, 25% of selected aluminum shavings, 15% of selected low sulfur fluorite sand, control the ratio of granules to powder to be 2 / 3, after being homogenized by a mixer, and carried into the forced feeding silo (intermediate silo) by a bucket elevator.

[0028] (3) After the above-mentioned fluffy material is fed by the forced feeder, its volume is compressed to 1 / 4 of the original volume. It is then fed into the roller press mold and rolled into strips of 100mm×20mm×10mm under a pressure of 22MPa.

[0029] (4) The strip-shaped material falls naturally into the blade crusher for crushing and the cage pelletizer for granulation of 0-50mm. After crushing and granulation, the material is screened by a multi-layer shaking table vibrating screen to separate qualified particles of 5-50mm.

[0030] (5) After the above components are prepared by a non-pre-melting cold forming process, according to Figure 4 The production process involves passivation treatment with 0.4% methyl silicone oil in the finished product, followed by packaging for later use. This is designated as desulfurizing agent 1.

[0031] The low-cost and high-efficiency desulfurizing agent 1 prepared according to the present invention was used in converter direct-fired continuous casting. The application process is as follows: 1) Before tapping steel from the converter, the material is discharged through the high-level silo at the top of the furnace, weighed by the metering conveyor belt, and added to the bottom of the ladle; 2) During the converter tapping process, the impact of molten steel creates the first stage of agitation and desulfurization; 3) A second deep desulfurization process is achieved by blowing Ar and stirring for 6 minutes; 4) After the sample passes the test, it is hoisted to the continuous casting station by an overhead crane. Experimental results: With an addition of 5 kg / ton of steel, the sulfur content decreased from 0.047% to 0.0119%, and the desulfurization rate was 74.6%, meeting the requirements for direct addition (S≤0.020%). From the slag sample, the newly developed desulfurizing agent 1 showed good adsorption of sulfur, promoting the separation of sulfur from molten steel and its entry into the steel slag. Specific data are shown in Tables 2 and 3.

[0032] Table 2. Furnace data before and after the experiment of Formula 1

[0033] Table 3. Comparison data of slag samples before and after the experiment of Formula 1

[0034] Example 2

[0035] A production process for preparing a low-cost, high-efficiency desulfurizing agent is described below: (1) According to Figure 1 , 2 The production process yields selected ultra-low sulfur metallurgical lime powder, selected aluminum shavings, and selected low-sulfur fluorite sand. The main physicochemical properties are shown in Table 4 below. Table 4

[0036] (2) Design a high-efficiency desulfurizer formula 2, the formula composition is: 70% of selected ultra-low sulfur metallurgical lime powder, 15% of selected aluminum shavings, and 15% of selected low sulfur fluorite sand; control the ratio of granular material to powder material to be 3 / 7, and after being homogenized by a mixer, it is carried into the forced feeding silo (intermediate silo) by a bucket elevator.

[0037] (3) After the above-mentioned fluffy material is fed by the forced feeder, its volume is compressed to 1 / 4 of the original volume. It is then fed into the roller press mold and rolled into strips of 100mm×20mm×10mm under a pressure of 22MPa.

[0038] (4) The strip-shaped material falls naturally into the blade crusher for crushing and the cage pelletizer for granulation of 0-50mm. After crushing and granulation, the material is screened by a multi-layer shaking table vibrating screen to separate qualified particles of 5-50mm.

[0039] (5) After the above components are prepared by a non-pre-melting cold forming process, according to Figure 4 The production process involves passivation treatment with 0.4% methyl silicone oil in the finished product, followed by packaging for later use. This is designated as desulfurizing agent 2.

[0040] The low-cost and high-efficiency desulfurizing agent 2 prepared according to the present invention was used in converter direct-fired continuous casting. The application process is as follows: 1) Before tapping steel from the converter, the material is discharged through the high-level silo at the top of the furnace, weighed via a metering conveyor belt, and added to the bottom of the ladle; 2) During the converter tapping process, the impact of molten steel creates the first stage of agitation and desulfurization; 3) A second deep desulfurization process is achieved by blowing Ar and stirring for 7 minutes; 4) After the sample passes the test, it is hoisted to the continuous casting station by the overhead crane.

[0041] Experimental results: With an addition of 2.5 kg / ton of steel, the average sulfur content decreased from 0.0295% to 0.0131%, and the desulfurization rate was 54.9%; both met the requirements for direct addition (S≤0.020%). From the slag samples, the newly developed desulfurizing agent 2 also showed good adsorption of S, promoting the separation of S from molten steel and into the steel slag. Specific data are shown in Tables 5 and 6.

[0042] Table 5. Furnace data after Formula 2 test

[0043] Table 6. Comparison data of slag samples after Formula 2 test .

Claims

1. A low-cost, high-efficiency desulfurizing agent for direct-fired converter casting, characterized in that... It is prepared from the following raw materials: Ultra-low sulfur metallurgical lime powder 60-80%, aluminum shavings 10-25%, low sulfur fluorite sand 10-15%; The ultra-low sulfur metallurgical lime powder has a sulfur content of S% < 0.010%; the aluminum shavings contain ≥ 70% metallic aluminum and 10%-30% alumina by weight; the low-sulfur fluorite sand contains 0.010% ≤ S% ≤ 0.030% sulfur, 94-96% calcium fluoride, and less than 1% moisture. The preparation process of the ultra-low sulfur metallurgical lime powder is as follows: (1) In a 1000T / D rotary kiln for lime production, a strong oxidation technology is used, consisting of 90% Fugu low-sulfur anthracite and 10% diesel fuel, with a coal injection rate of 9200kg / h, an oil injection rate of 0.92kg / h, and a secondary air volume greater than 51000Nm³. 3 Under operating conditions of / h, low-sulfur limestone is calcined at 1250-1320℃ to produce low-sulfur lime blocks A with a sulfur content of less than 0.025% and a particle size of 10-40mm. (2) 10-40mm low sulfur lime blocks A are crushed by a 0-15mm low speed compound crusher, and under the action of a closed rolling screen, 5-15mm block material B and 0-5mm powder material C are separated. Powder C contains high-sulfur kiln crust, slag, and clay, which are used for sintering. (3) 5-15mm block material B is crushed by a 0-5mm medium-speed compound crusher, and under the action of a cyclone dust collector, 0-1mm ultra-low sulfur metallurgical lime powder and 1-5mm small block material D are separated; among them, small block material D contains hard kiln skin with high sulfur content, quick-burned lime, and miscellaneous stone, which are used for sintering.

2. A production process for a low-cost, high-efficiency desulfurizing agent for converter direct-fired continuous casting as described in claim 1, characterized in that... The specific steps are as follows: (1) Obtaining low-sulfur raw materials: Using the Fugu low-sulfur anthracite coal and diesel co-firing strong oxidation technology, low-sulfur lime blocks A with a sulfur content of less than 0.025% were produced; (2) Deep processing of raw materials: aluminum scrap, ultra-low sulfur metallurgical lime powder and low sulfur fluorite sand are obtained at low cost through off-line selection and impurity removal processes; (3) Product preparation: The obtained raw materials are mixed evenly by mass percentage: 60-80% of ultra-low sulfur metallurgical lime powder, 10-25% of aluminum shavings, and 10-15% of low sulfur fluorite sand. The mixture is fed into a high-pressure roller press by a forced feeder and rolled into strips of 100mm×20mm×10mm. The strips fall naturally into a blade crusher and a granulator for crushing. The qualified particles are screened out to a size of 5-50mm. The unqualified powder is recycled back into the roller press for molding. (4) Product passivation: Weigh 0.3-0.5% of the total mass of the above products with methyl silicone oil, pressurize it through a variable frequency metering pump of 0.1-0.5L / min, and heat it to 80-100℃ through a conveying pipe with a heat tracing cable. Finally, passivate the finished product through an atomizing nozzle to reduce water absorption and powdering, ensure product storage time, and solve the powdering defect of non-pre-melted cold forming.

3. The production process of the low-cost and high-efficiency desulfurizing agent for converter direct-flow continuous casting according to claim 2, characterized in that: The preparation process of the low-sulfur fluorite sand is as follows: (1) After the fluorite ore is crushed by a jaw crusher with a diameter of 0-80mm, it is spread out by a loader and then the silica and vein skin are picked out manually. (2) After stirring and washing, fluorite with high sulfur content is removed from fluorite fabric with 0-80mm fluorite. (3) After the above steps, the fluorite blocks are naturally air-dried, and the sulfur content is reduced from 0.35-0.50% to 0.010-0.030%, the calcium fluoride content is increased from 85-90% to 94-96%, and the moisture content is reduced from more than 5% to less than 1%. (4) Low-moisture fluorite blocks are crushed by a 0-2mm low-speed compound crusher to obtain low-sulfur fluorite sand.

4. The production process of the low-cost and high-efficiency desulfurizing agent for converter direct-flow continuous casting according to claim 2, characterized in that: The main process for preparing the aluminum scrap is as follows: primary aluminum slag → crushing → ball milling → closed drum screen screening → aluminum scrap; specifically including the following steps: (1) The aluminum slag is crushed into small pieces of 0-15mm by a 0-15mm jaw crusher; (2) After being ground and separated by an aluminum slag ball mill, the small pieces of material of 0-15mm enter a closed rotating screen to separate 2-15mm of selected aluminum chips and 0-2mm of secondary aluminum slag. (3) Secondary aluminum slag is sent to the cement plant to make rapid hard cement CA-50 raw material.

5. The production process of the low-cost and high-efficiency desulfurizing agent for converter direct-flow continuous casting according to claim 2, characterized in that... Specifically, the following steps are included: (1) The raw materials are packed according to the principle of the most compact packing, with small-particle low-sulfur fluorite sand and aluminum shavings as aggregates, and ultra-low sulfur metallurgical lime powder as filler. The ratio of aggregate to powder is controlled to be 1 / 4 to 2 / 3. After being homogenized by a mixer, the raw materials are carried into the forced feeding silo by a bucket elevator. (2) Under the action of the screw forced feeder, the volume of the above loose material is compressed to 1 / 4 of the original volume after passing through the forced feeder; (3) The compressed material is fed into the roller table of the high pressure roller press by a forced feeder and rolled into strips of 100mm×20mm×10mm under a pressure of 15-25MPa. (4) The strip-shaped material falls naturally into the blade crusher for crushing and the 0-50mm cage pelletizer for pelletizing; (5) The crushed and granulated material is screened by a multi-layer shaking table vibrating screen to separate qualified particles of 5-50mm. Unqualified material is recycled back into the roller press for molding. (6) Passivation treatment: Methyl silicone oil is delivered by a variable frequency metering pump and heated to 80-100°C through a conveying pipe with a heat tracing cable. The finished material is then passivated by an atomizing nozzle to reduce water absorption and powdering, ensure product storage time, and solve the powdering defect of non-pre-melted cold forming.

6. A method for using the low-cost, high-efficiency desulfurizing agent for direct-fired converter casting as described in claim 1, characterized in that... The specific steps are as follows: (1) Before tapping steel from the converter, desulfurizing agent is put into the high-level silo at the top of the furnace, weighed by the metering belt, and added to the bottom of the ladle; (2) During the tapping process of the converter, the molten steel impacts and forms the first stirring desulfurization; (3) Stirring with Ar for 5-8 minutes to form a second deep desulfurization process; (4) After the sample is tested and found to be qualified, it is hoisted to the continuous casting station by the overhead crane.

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