Method for calculating adsorption weight of CaO-Al2O3-based tundish covering agent on Al2O3 inclusion in tundish casting area and application of CaO-Al2O3-based tundish covering agent

Abstract

The invention provides a method for calculating the adsorption weight of a CaO-Al2O3-based tundish covering agent on Al2O3 inclusion in a tundish casting area. The method comprises the following steps: S1) detecting the content of CaO and Al2O3 in the CaO-Al2O3-based tundish covering agent before use; s2, the molten steel is cast, a tundish is cast into a first furnace, and a tundish covering agent is added into a tundish casting area; the last furnace of tundish casting is carried out, and the content of CaO and the content of Al2O3 in tundish slag are detected; s3) calculating the weight of CaO and Al2O3 in the tundish covering agent; calculating the content ratio of Al2O3 to CaO in the tundish slag; s4) calculating the weight of Al2O3 in the tundish slag according to the mass conservation of CaO; and calculating the adsorption quantity of the tundish covering agent in the tundish casting area to the Al2O3 inclusion. According to the calculation method provided by the invention, the adsorption removal amount of the Al2O3 inclusion can be accurately calculated by taking the component CaO in the tundish covering agent as the marker.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a method for calculating the adsorption weight of Al2O3 inclusions in a casting zone of a ladle by a CaO-Al2O3-based ladle covering agent and its application. Background Art

[0002] The tundish covering agent is an important auxiliary material in the continuous casting process. It keeps the molten steel in the tundish warm and prevents the molten steel from direct contact with the air and secondary oxidation. In addition, for steel grades with high cleanliness requirements, the covering agent in the tundish also plays an important metallurgical function of absorbing and dissolving inclusions in the molten steel and purifying the molten steel.

[0003] In order to enhance the metallurgical function of the tundish covering agent, many researchers have carried out optimization design work on the tundish covering agent based on the characteristics of the steel grade. For example: Chinese patent publication number CN117920953A discloses a tundish covering agent for electrical steel and a preparation method thereof, which uses a mixture of electrical steel refining top slag and prefabricated slag as a tundish covering agent for electrical steel continuous casting production, effectively improving the slag-like physical and chemical properties of the covering agent, making it have good fluidity, avoiding the occurrence of crusting, and improving the ability to absorb inclusions; Chinese patent publication number CN117210641A discloses a preparation method for a tundish covering agent for ultra-low sulfur steel, which controls the slag during refining. The amount of lime added and the reduction of the initial sulfur content of molten steel make the slag smelting still have a high sulfur capacity after refining, and then it is recycled by cooling to make a tundish covering agent, which can not only reduce the production cost, but also effectively ensure that the molten steel does not increase sulfur during casting; the Chinese patent with publication number CN116987841A provides a tundish covering agent for the production of high-quality carbon structural steel and a preparation method thereof. The prepared tundish covering agent has good thermal insulation effect, can effectively absorb inclusions and melt quickly, and can reduce the pollution to the molten steel, and makes full use of Various waste materials, realizing waste utilization and low-carbon environmental protection; Chinese patent application number CN202310690778.9 discloses a low-silicon, low-carbon, smokeless electric melting hollow covering agent for tundish and its preparation method, the prepared covering agent has the characteristics of no carbon, high strength, good thermal insulation performance, good spreadability, light specific gravity, small dosage, no ignition loss, and strong ability to adsorb impurities; Chinese patent application number CN116479212A discloses a new type of environmentally friendly ladle covering agent and its preparation method and application, which can achieve steel The water keeps the molten steel warm without polluting it, thus playing a role in heat insulation and heat preservation, and greatly reducing dust, which can further reduce the impact of the molten steel on the environment during the smelting process; the Chinese patent with publication number CN116041079A discloses a tundish covering agent with improved thermal insulation performance and a preparation method thereof, which has the characteristics of high basicity, strong ability to remove inclusions, no hardening and no corrosion of the lining after long-term use, and better thermal insulation than carbon-free calcium-aluminum-magnesium hollow particle covering agents, and can be widely used in the production of various high value-added steels.

[0004] The above patent aims to improve the physicochemical properties of the tundish slag and its metallurgical function in the steelmaking process by optimizing the composition and preparation process of the tundish covering agent. However, the current patent does not involve the quantitative calibration and evaluation method of the inclusion adsorption weight of the tundish covering agent, so it is difficult to accurately evaluate the inclusion adsorption capacity of the covering agent after optimization. Summary of the invention

[0005] The technical problem solved by the present invention is to provide a method for calculating the adsorption weight of Al2O3 inclusions in the casting area of ​​the middle ladle by a CaO-Al2O3-based middle ladle covering agent. The calculation method provided in this application can accurately calculate the adsorption amount of Al2O3 inclusions by the middle ladle covering agent.

[0006] In view of this, the present application provides a method for calculating the adsorption weight of Al2O3 inclusions in the casting area of ​​the ladle by a CaO-Al2O3-based ladle covering agent, comprising the following steps:

[0007] S1) Detect the contents of CaO and Al2O3 in the CaO-Al2O3-based coating agent before use, which are respectively denoted as w 1C 、w 1A , wt%;

[0008] S2) casting the molten steel, pouring the first furnace of the tundish, and adding W1 kg of the tundish covering agent into the tundish casting area;

[0009] After the last batch of tundish casting, the contents of CaO and Al2O3 in the tundish slag were detected and recorded as w 2C 、w 2A , wt%;

[0010] S3) Calculate the weight of CaO and Al2O3 in the middle package covering agent, and record them as W 1CaO , W 1Al2O3 , W 1CaO =W1×w 1C , kg, W 1Al2O3 =W1×w 1A , kg;

[0011] Calculate the ratio of Al2O3 to CaO in the tundish slag, R2, R2 = w 2A / w 2C ;

[0012] S4) According to the CaO mass conservation law, calculate the weight of Al2O3 in the tundish slag, recorded as W 2Al2O3 , W 2Al2O3 =W 1CaO × R2, kg; calculate the adsorption amount of Al2O3 inclusions by the tundish covering agent in the tundish casting area, recorded as W Al2O3夹杂 , W Al2O3夹杂 =W 2Al2O3 -W 1Al2O3 , kg.

[0013] Preferably, in step S1), the middle package covering agent includes CaO, Al2O3, MgO, and SiO2, wherein CaO / Al2O3=1-2.5, the content of MgO is 8-12wt%, and the content of SiO2 is ≤5wt%.

[0014] Preferably, in step S1), the detected amount of the middle package covering agent is ≥100g.

[0015] Preferably, in step S1), the detected amount of the middle package covering agent is 150-300 g.

[0016] Preferably, in step S2), the timing of adding the tundish covering agent is when the weight of the molten steel in the tundish reaches 40-60% of the nominal capacity.

[0017] Preferably, in step S2), the timing for detecting the tundish slag is when the weight of the large ladle of molten steel remains at 30-50%.

[0018] Preferably, in step S2), the detected amount of the middle ladle slag is ≥100g.

[0019] Preferably, in step S2), the detected amount of the middle bag slag is 200-300g.

[0020] Preferably, retaining walls are provided in the tundish casting zone and the impact zone, and the refractory material in the tundish casting zone does not include CaO.

[0021] The present application also provides the application of the calculation method in the design of the middle package covering agent.

[0022] The present application provides a method for calculating the adsorption weight of Al2O3 inclusions in the casting area of ​​the tundish by a CaO-Al2O3-based tundish covering agent. The method first detects the contents of CaO and Al2O3 in the CaO-Al2O3-based tundish covering agent before use, then casts molten steel, casts the first heat in the tundish, adds the tundish covering agent to the casting area of ​​the tundish, casts the last heat in the tundish, detects the contents of CaO and Al2O3 in the tundish slag, and then calculates the weight of CaO and Al2O3 in the initial tundish covering agent, the weight of the tundish slag, and the weight of the tundish slag. The content ratio of Al2O3 and CaO in the ladle slag; finally, according to the conservation of CaO mass, the adsorption amount of Al2O3 inclusions by the mid-ladle covering agent can be calculated on the basis of the calculated weight of Al2O3 in the mid-ladle slag; the calculation method provided in the present application is based on the CaO inherent component in the initial covering agent as a marker, and utilizes the conservation of CaO mass during the casting process and the changes in the detected components of the mid-ladle slag to accurately calculate the adsorption and removal amount of Al2O3 inclusions by the mid-ladle covering agent, providing key data support for optimizing the composition of the mid-ladle covering agent. DETAILED DESCRIPTION

[0023] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0024] In view of the lack of quantitative calibration pre-evaluation methods for the adsorption weight of inclusions by the middle ladle covering agent in the prior art, the present application provides a method for accurately calibrating and calculating the adsorption weight of Al2O3 inclusions by the ladle casting zone covering agent during steel casting. By using CaO, a self-component in the middle ladle covering agent, as a marker, the adsorption removal amount of Al2O3 inclusions by the middle ladle covering agent can be accurately calculated, which can provide key data support for optimizing the composition of the middle ladle covering agent. Specifically, an embodiment of the present invention discloses a method for calculating the adsorption weight of Al2O3 inclusions in the middle ladle casting zone by a CaO-Al2O3-based middle ladle covering agent, comprising the following steps:

[0025] S1) Detect the contents of CaO and Al2O3 in the CaO-Al2O3-based coating agent before use, which are respectively denoted as w 1C 、w 1A , wt%,

[0026] S2) casting the molten steel, pouring the first furnace of the tundish, and adding W1 kg of the tundish covering agent into the tundish casting area;

[0027] After the last batch of tundish casting, the contents of CaO and Al2O3 in the tundish slag were detected and recorded as w 2C 、w 2A , wt%;

[0028] S3) Calculate the weight of CaO and Al2O3 in the middle package covering agent, and record them as W 1CaO , W 1Al2O3 , W 1CaO =W1×w 1C , kg, W 1Al2O3 =W1×w 1A , kg;

[0029] Calculate the ratio of Al2O3 to CaO in the tundish slag, R2, R2 = w 2A / w 2C ;

[0030] S4) According to the CaO mass conservation law, calculate the weight of Al2O3 in the tundish slag, recorded as W 2Al2O3 , W 2Al2O3 =W 1CaO × R2, kg; calculate the adsorption amount of Al2O3 inclusions by the tundish covering agent in the tundish casting area, recorded as W Al2O3夹杂 , W Al2O3夹杂 =W 2Al2O3 -W 1Al2O3 , kg.

[0031] The calculation method provided in this application is aimed at calculating the adsorption weight of Al2O3 inclusions by the CaO-Al2O3-based tundish covering agent in the casting area of ​​the continuous casting tundish during the casting process. There is no special restriction on the type of steel, but it is mainly aimed at the tundish covering agent with CaO-Al2O3 as the main component; that is, the calculation method provided in this application has good applicability.

[0032] First, the present invention detects the contents of CaO and Al2O3 in the CaO-Al2O3-based coating agent before use, which are respectively denoted as w 1C 、w 1A , wt%; wherein the detected amount of the middle package covering agent is ≥100g, specifically, the detected amount of the middle package covering agent is 150-300g. In the present application, the components of the middle package covering agent include CaO, Al2O3, MgO, SiO2, wherein CaO / Al2O3=1-2.5, the content of MgO is 8-12wt%, and the content of SiO2 is ≤5wt%.

[0033] The molten steel is cast, and the first furnace is poured in the tundish. Preferably, when the weight of the molten steel in the tundish reaches 40-60wt% of the nominal capacity, a certain amount of tundish covering agent is added to the tundish casting area and other areas. The amount of the tundish covering agent added is recorded as W1 kg; specifically, the timing of adding the tundish covering agent is when the weight of the molten steel in the tundish reaches 45-55wt% of the nominal capacity; if the tundish covering agent is added too early, due to the small amount of molten steel in the tundish, the added tundish covering agent has a greater impact on the stability of the molten steel flow field, which is easy to cause slag rolling and affect the purity of the molten steel; if it is added too late, the molten steel entering the tundish before the covering agent is added lacks the covering and protection effect of the tundish covering agent, and is easily secondary oxidized by the air, affecting the purity of the molten steel. On this basis, the contents of MgO and CaO in the above-mentioned added tundish covering agent are calculated respectively, and recorded as W 1CaO , W 1Al2O3 , W 1CaO =W1×w 1C , kg, W 1Al2O3 =W1×w 1A , kg.

[0034] In the last batch of tundish casting, preferably when the weight of the molten steel in the large ladle remains 30-50wt%, the tundish slag is taken in the tundish casting area. The tundish slag is formed after the tundish covering agent melts and absorbs inclusions. The CaO and Al2O3 contents in it are detected and recorded as w 2C 、w 2A , wt%; and based on this, the content ratio of CaO and Al2O3 in the middle ladle slag is calculated R2 = w 2A / w 2CSpecifically, the detection time of the middle ladle slag is when the weight of the large ladle molten steel remains 35-45wt%. The detection amount of the middle ladle slag is ≥100g, specifically, the detection amount of the middle ladle slag is 200-300g.

[0035] Since a retaining wall is usually installed between the tundish casting area and the impact area, it can effectively block the slag (containing CaO) from the ladle from flowing to the casting area. At the same time, the refractory material in the casting does not contain CaO. Therefore, it can be considered that the mass of CaO in the tundish covering agent in the casting area is conserved, that is, the mass of CaO in the tundish covering agent and the tundish slag remains unchanged. Based on this, the weight of Al2O3 in the tundish slag in the casting area when the tundish is cast for the last batch can be quantitatively calculated and determined, which is recorded as W. 2Al2O3 , W 2Al2O3 =W 1CaO × R2, kg. In the process of calculating the weight of Al2O3 inclusion adsorption, this application uses CaO as a marker because the refractory material in the casting area of ​​the tundish does not contain CaO, and the mass of CaO is conserved, that is, the mass of CaO in the tundish covering agent remains unchanged during the casting process.

[0036] Based on the above calculation, the weight increment of Al2O3 in the tundish slag relative to the weight increment of Al2O3 in the tundish covering agent is the weight of Al2O3 inclusions adsorbed by the tundish covering agent in the casting area during the tundish casting process, which is recorded as W Al2O3夹杂 , W Al2O3夹杂 =W 2Al2O3 -W 1Al2O3 , kg.

[0037] The present application also provides the application of the above-mentioned calculation method in the design of the middle bag covering agent; the design can be the design of the specific composition of the middle bag covering agent. According to the adsorption weight of the original middle bag covering agent for Al2O3 inclusions calculated by the above-mentioned calculation method, the composition of the middle bag covering agent can be further adjusted to increase the adsorption amount of Al2O3 inclusions.

[0038] The present application provides a quantitative calculation and evaluation method for the weight of Al2O3 inclusions adsorbed by the ladle covering agent during continuous casting, which includes the following steps: (1) based on the weight of the middle ladle covering agent added and the detected components, the weight of CaO and Al2O3 initially added is determined; (2) after the steel casting is completed, the components of the middle ladle covering agent are detected and CaO / Al2O3 is determined; (3) the CaO mass in the ladle casting area during the steel casting process is conserved, and the weight of Al2O3 adsorbed by the ladle covering agent during the steel casting process can be calculated based on the weight of CaO and Al2O3 added and the new CaO / Al2O3 after the steel casting is completed. The calculation method provided by the present invention can accurately calculate and determine the weight of Al2O3 inclusions adsorbed by the covering agent in the ladle casting area during the steel casting process, and provide accurate data support for optimizing the covering agent components and improving its inclusion adsorption performance, thereby enhancing the cleanliness of molten steel of key varieties of steel such as automobile plates, reducing the economic losses caused by inclusion degradation, and is expected to create an annual benefit of at least 500,000 yuan.

[0039] In order to further understand the present invention, the calculation method of the adsorption weight of Al2O3 inclusions in the casting area of ​​the middle ladle by the CaO-Al2O3 based middle ladle covering agent provided by the present invention is described in detail in combination with the embodiments below. The protection scope of the present invention is not limited by the following embodiments.

[0040] Example Calculation of the adsorption weight of Al2O3 inclusions by the tundish covering agent in the rear casting area of ​​the two-stream 70-ton tundish for continuous casting of 10 furnaces of high-cleanliness IF steel

[0041] (1) Take 150g of the CaO-Al2O3-based coating agent before use, and detect and analyze its CaO and Al2O3 contents, which are recorded as w 1C =30.75%, w 1A =23.21%;

[0042] (2) The first furnace is poured in the tundish. When the weight of the molten steel in the tundish reaches 50% of the nominal capacity, a certain amount of covering agent is added to the casting area and other areas of the tundish. The weight of the covering agent added to the casting area is W1 = 160 kg.

[0043] (3) In the last batch of tundish casting, when the weight of the molten steel in the large ladle remains at 30%, 200g of tundish slag is taken from the tundish casting area to test the CaO and Al2O3 contents of the tundish slag, which are w 2C =23.17%, w 2A =24.67%;

[0044] (4) Calculate the weight of CaO and Al2O3 covering agents before use, which are W 1CaO =W1×w 1C =160kg×30.75%=49.2kg, W 1Al2O3 =W1×w 1A=160kg×23.21%=37.1kg;

[0045] (5) Calculate the ratio of Al2O3 to CaO in the slag of the last batch of tundish casting (R2 = w) 2A / w 2C =24.67% / 23.17%=1.06;

[0046] (6) Since a retaining wall is usually installed between the tundish casting area and the impact area, it can effectively block the slag (containing CaO) from the ladle from flowing to the casting area. At the same time, the refractory in the casting area does not contain CaO. Therefore, it can be considered that the mass of CaO in the tundish covering agent added to the casting area is conserved. Based on this, the weight of Al2O3 in the tundish slag in the casting area when the tundish is cast for the last batch can be quantitatively calculated. 2Al2O3 =W 1CaO ×R2=49.2kg×1.06=52.2kg;

[0047] (7) Based on steps (1) to (6), the adsorption weight W of Al2O3 inclusions by the coating agent in the casting area can be accurately calculated and determined during the casting process. Al2O3夹杂 =W 2Al2O3 -W 1Al2O3 =52.2kg-37.1kg=15.1kg.

[0048] In order to verify the accuracy of the calculation method provided by the present application, in the above embodiment, after the last batch of ladle casting, the weight of the ladle covering agent in the casting area was collected and weighed, which was 212.6kg. The Al2O3 content detection value of the ladle covering agent in the last batch was 24.67%, so the actual weight of Al2O3 in the ladle casting area covering agent in the last batch was 212.6kg×24.67%=52.4kg; the above embodiment step (5) has calculated and determined that the weight of Al2O3 initially added to the covering agent before use is 37.1kg, so the actual weight of Al2O3 adsorbed by the covering agent during the ladle casting process is 52.4kg-37.1kg=15.3kg. The Al2O3 adsorption weight calculated and determined by the calculation method provided by the present application in the embodiment is 15.1kg, which is consistent with the measured result of 15.3kg, proving the reliability and accuracy of the calculation method of the present application.

[0049] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0050] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for calculating the adsorption weight of Al2O3 inclusions in the casting area of ​​a ladle by a CaO-Al2O3-based ladle covering agent, comprising the following steps: S1) Detect the contents of CaO and Al2O3 in the CaO-Al2O3-based coating agent before use, which are respectively denoted as w 1C 、w 1A , wt%; S2) casting the molten steel, pouring the first furnace of the tundish, and adding W1kg of the tundish covering agent into the tundish casting area; After the last batch of tundish casting, the contents of CaO and Al2O3 in the tundish slag were detected and recorded as w 2C 、w 2A , wt%; S3) Calculate the weight of CaO and Al2O3 in the middle package covering agent, and record them as W 1CaO , W 1Al2O3 , W 1CaO =W1×w 1C , kg, W 1Al2O3 =W1×w 1A , kg; Calculate the ratio of Al2O3 to CaO in the tundish slag, R2, R2 = w 2A / w 2C ; S4) According to the CaO mass conservation law, calculate the weight of Al2O3 in the tundish slag, recorded as W 2Al2O3 , W 2Al2O3 =W 1CaO × R2, kg; calculate the adsorption amount of Al2O3 inclusions by the tundish covering agent in the tundish casting area, recorded as W Al2O3夹杂 , W Al2O3夹杂 =W 2Al2O3 -W 1Al2O3 , kg.

2. The calculation method according to claim 1, characterized in that: In step S1), the middle package covering agent includes CaO, Al2O3, MgO, and SiO2, wherein CaO / Al2O3=1-2.5, the content of MgO is 8-12wt%, and the content of SiO2 is ≤5wt%.

3. The calculation method according to claim 1, characterized in that: In step S1), the detected amount of the middle package covering agent is ≥100g.

4. The calculation method according to claim 1 or 3, characterized in that: In step S1), the detected amount of the middle package covering agent is 150-300 g.

5. The calculation method according to claim 1, characterized in that: In step S2), the timing of adding the tundish covering agent is when the weight of the molten steel in the tundish reaches 40-60% of the nominal capacity.

6. The calculation method according to claim 1, characterized in that: In step S2), the timing for detecting the tundish slag is when the weight of the large ladle of molten steel remains at 30-50%.

7. The calculation method according to claim 1, characterized in that: In step S2), the detected amount of the middle ladle slag is ≥100g.

8. The calculation method according to claim 1 or 7, characterized in that: In step S2), the detected amount of the tundish slag is 200-300 g.

9. The calculation method according to claim 1, characterized in that: The tundish casting zone and the impact zone are provided with retaining walls, and the refractory material in the tundish casting zone does not include CaO.

10. Application of the calculation method according to any one of claims 1 to 9 in the design of a middle package covering agent.