Calculation method of adsorption capacity of CaO-Al2O3 covering agent to inclusions and application of CaO-Al2O3 covering agent

Abstract

The invention provides a method for calculating the adsorption capacity of a CaO-Al2O3 covering agent to inclusions, which comprises the following steps: S1) defining the adsorption capacity as I, and calculating according to a formula I; s2) detecting the mass percentage content of CaO and Al2O3 in the initial CaO-Al2O3 covering agent; s3) adsorbing Al2O3 inclusions by using an initial CaO-Al2O3 covering agent, defining a calcium-aluminum ratio K during saturation, and calculating a formula as a formula II; s4) after the adsorption is completed, calculating the weight QI of the Al2O3 inclusion in the CaO-Al2O3 covering agent according to a calculation formula III; s5) combining the calculation formula III and the calculation formula I to obtain the adsorption capacity I of the CaO-Al2O3 covering agent to the inclusions; according to the calculation method, the inclusion adsorption capacity of the covering agent can be rapidly calculated, then the adding amount of the covering agent is accurately determined, and the problems of cost, molten steel cleanliness and the like caused by unreasonable adding of the covering agent are solved.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a method for calculating the adsorption capacity of a CaO-Al2O3 series covering agent for inclusions and application thereof. Background Art

[0002] The tundish covering agent is an important metallurgical 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. The Chinese patent with publication number CN117920953A provides a tundish covering agent and a preparation method for electrical steel, which effectively improves the slag-like physicochemical properties of the covering agent and enhances the ability to adsorb inclusions; the Chinese patent with publication number CN117210641A provides a preparation method for a tundish covering agent for ultra-low sulfur steel, which can reduce production costs and effectively ensure that the molten steel does not increase S during casting by controlling the amount of lime added during refining and reducing the initial S content of molten steel; the Chinese patent with publication number CN116987841A discloses a tundish covering agent and a preparation method for the production of high-quality carbon structural steel, which can effectively adsorb inclusions and melt quickly, reduce pollution to molten steel, and make full use of various waste materials. Material; Chinese patent application number CN202310690778.9 discloses a low-silicon, low-carbon, smokeless electric melting hollow covering agent for tundish and its preparation method, which has the advantages of 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 has excellent thermal insulation and heat preservation effects, and significantly reduces dust pollution; Chinese patent application number CN116041079A discloses a tundish covering agent with improved thermal insulation performance and its preparation method, which improves its adsorption and removal ability of inclusions through higher basicity, and has the advantages of excellent slag-removing performance and low corrosion of tundish refractory materials.

[0004] The above patent effectively improves the metallurgical function of the tundish covering agent by optimizing the composition and processing technology of the covering agent. However, in terms of the covering agent's inclusion adsorption capacity, the existing technology mainly relies on on-site industrial test evaluation, and does not propose a theoretical calculation method for the covering agent's inclusion adsorption capacity, which cannot provide a theoretical basis for the rapid evaluation and adjustment of the covering agent technical solution. Summary of the invention

[0005] The technical problem solved by the present invention is to provide a method for calculating the adsorption capacity of a CaO-Al2O3 series covering agent for inclusions. The calculation method provided in the present application can quickly calculate the adsorption capacity of a CaO-Al2O3 series covering agent for inclusions, and then accurately determine the amount of covering agent added, thereby avoiding problems such as cost and molten steel cleanliness caused by unreasonable addition of covering agent.

[0006] In view of this, the present application provides a method for calculating the adsorption capacity of a CaO-Al2O3 system covering agent for inclusions, comprising the following steps:

[0007] S1) The adsorption capacity of the CaO-Al2O3 system covering agent for Al2O3 inclusions is defined as I, and the calculation formula of I is shown in (Ⅰ):

[0008]

[0009] S2) Detect the mass percentage of CaO and Al2O3 in the initial CaO-Al2O3 system covering agent, which are respectively recorded as w 1C 、w 1A , wt%;

[0010] S3) using the initial CaO-Al2O3 system covering agent to adsorb Al2O3 inclusions, and the ratio of CaO to Al2O3 when saturation is reached is defined as the calcium-aluminum ratio K, and the calculation formula of the ratio and the temperature of the molten steel in the continuous casting process is shown in formula (II):

[0011] K=-8.195+0.01482×T-5.9497×10 -6 ×T 2 (Ⅱ);

[0012] S4) After the adsorption is saturated, the weight of Al2O3 inclusions in the CaO-Al2O3 system covering agent is obtained. I Calculate according to formula (III):

[0013] Q I =W Al2O3 -W' Al2O3 =Q s ×(w 1C / Kw 1A ) (III);

[0014] S5) combining the calculation formula (III) with the calculation formula (I) to obtain the adsorption capacity I of the CaO-Al2O3 system covering agent for inclusions;

[0015] Among them, Q s is the initial weight of CaO-Al2O3 system covering agent, kg; Q I is the weight of Al2O3 inclusions when they reach saturation in the covering agent, kg;

[0016] T is the average temperature of molten steel during continuous casting, °C;

[0017] W' Al2O3 is the weight of Al2O3 in the initial CaO-Al2O3 system covering agent, kg;

[0018] W Al2O3 It is the total weight of Al2O3 when the CaO-Al2O3 system covering agent is saturated with adsorption, kg.

[0019] Preferably, T is 1350-1550°C.

[0020] Preferably, the formula (II) is obtained by the following method:

[0021] The calcium-aluminum ratios of different initial CaO-Al2O3 system covering agents at different temperatures when Al2O3 inclusions are adsorbed saturated are calculated using thermodynamic calculation software to obtain a curve of the calcium-aluminum ratio and temperature when the covering agent is adsorbed saturated; the calcium-aluminum ratios of the initial CaO-Al2O3 system covering agents are different;

[0022] The temperature and calcium-aluminum ratio when the covering agent is adsorbed to saturation are fitted.

[0023] Preferably, w 1C 30~60wt% 1A It is 10~25wt%.

[0024] Preferably, in step S2), the weight of the initial CaO-Al2O3 based covering agent is ≥100 g.

[0025] Preferably, K is 0.3-0.6.

[0026] Preferably, the formula (III) further comprises:

[0027] The CaO-Al2O3 system covering agent is adsorbed to saturation, and the total weight of Al2O3 in the covering agent is W Al2O3 The calculation is carried out according to the following formula:

[0028] W Al2O3 =W' CaO / K=Q s × 1C / K.

[0029] The present application also provides the application of the calculation method in determining the initial addition amount of CaO-Al2O3 system covering agent in the continuous casting tundish.

[0030] The present application provides a method for calculating the adsorption capacity of a CaO-Al2O3 system covering agent for inclusions. First, the adsorption capacity I of the CaO-Al2O3 system covering agent for Al2O3 inclusions is defined, the mass percentage of CaO and Al2O3 in the initial CaO-Al2O3 system covering agent is detected, and the Al2O3 inclusions are adsorbed by the covering agent. The ratio of CaO to Al2O3 when saturation is reached is defined as the calcium-aluminum ratio K. After the adsorption is completed, the weight Q of the Al2O3 inclusions in the CaO-Al2O3 system covering agent is obtained based on the conservation of mass of calcium oxide in the adsorbent. I , Q I Substituting into the expression of adsorption capacity, the adsorption capacity of the covering agent for inclusions can be obtained; the calculation method provided in this application is based on the steel pouring temperature and the covering agent composition, and can quickly and quantitatively calculate the adsorption capacity of the covering agent for inclusions, avoiding the cost, molten steel cleanliness and other problems caused by unreasonable addition of covering agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The relationship diagram of the calcium-aluminum ratio of the covering agents with different initial calcium-aluminum ratios at different temperatures when the Al2O3 inclusions are adsorbed saturatedly;

[0032] Figure 2 This is a graph showing the relationship between the calcium-aluminum ratio and the absorption of inclusions by the covering agent CaO / Al2O3 during the ladle casting process in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] 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.

[0034] In view of the lack of theoretical basis for evaluating the adsorption capacity of inclusions by covering agents in the prior art, this application provides a method for calculating the adsorption capacity of inclusions by a CaO-Al2O3-based covering agent. Based on the steel pouring temperature and the composition of the covering agent, the corresponding adsorption capacity of inclusions can be quickly and quantitatively calculated, filling the gap in current technical inventions. The calculation method provided by this application can quickly calculate and determine the theoretical amount of covering agent added, avoiding the cost, cleanliness of molten steel and other problems caused by unreasonable addition of covering agents. The embodiment of the present invention discloses a method for calculating the adsorption capacity of inclusions by a CaO-Al2O3-based covering agent, comprising the following steps:

[0035] S1) The adsorption capacity of the CaO-Al2O3 system covering agent for Al2O3 inclusions is defined as I, and the calculation formula of I is shown in (Ⅰ):

[0036]

[0037] S2) Detect the mass percentage of CaO and Al2O3 in the initial CaO-Al2O3 system covering agent, which are respectively recorded as w 1C 、w 1A , wt%;

[0038] S3) using the initial CaO-Al2O3 system covering agent to adsorb Al2O3 inclusions, and the ratio of CaO to Al2O3 when saturation is reached is defined as the calcium-aluminum ratio K, and the calculation formula of the ratio and the temperature of the molten steel in the continuous casting process is shown in formula (II):

[0039] K=-8.195+0.01482×T-5.9497×10 -6 ×T 2 (Ⅱ);

[0040] S4) After the adsorption is saturated, the weight of Al2O3 inclusions in the CaO-Al2O3 system covering agent is obtained. I Calculate according to formula (III):

[0041] Q I =W Al2O3 -W' Al2O3 =Q s ×(w 1C / Kw 1A ) (III);

[0042] S5) combining the calculation formula (III) with the calculation formula (I) to obtain the adsorption capacity I of the CaO-Al2O3 system covering agent for inclusions;

[0043] Among them, Q s is the initial weight of CaO-Al2O3 system covering agent, kg; Q I is the weight of Al2O3 inclusions when they reach saturation in the covering agent, kg;

[0044] T is the average temperature of molten steel during continuous casting, °C;

[0045] W' Al2O3 is the weight of Al2O3 in the initial CaO-Al2O3 system covering agent, kg;

[0046] W Al2O3 It is the total weight of Al2O3 when the CaO-Al2O3 system covering agent is saturated with adsorption, kg.

[0047] In the calculation method of the adsorption capacity of the CaO-Al2O3 system covering agent for inclusions, the present application first defines the adsorption capacity of the CaO-Al2O3 system covering agent for Al2O3 inclusions as I, and the calculation formula of I is shown in (I):

[0048]

[0049] Among them, Q s is the initial weight of CaO-Al2O3 system covering agent, kg; Q I is the weight of Al2O3 inclusions when the covering agent reaches saturation, kg. When the CaO-Al2O3 covering agent is saturated with adsorption, only the weight of Al2O3 inclusions increases. Therefore, the ratio of the weight of the covering agent at saturation with adsorption to the weight of the initial adsorbent has a high accuracy in characterizing the adsorption amount of Al2O3 inclusions by the covering agent.

[0050] The present application firstly detects the mass percentage of CaO and Al2O3 in the initial CaO-Al2O3 system covering agent, which are respectively denoted as w 1C 、w 1A , wt%; example, w 1C 30~60wt% 1A In order to test accurately and facilitate sampling, the weight of the initial CaO-Al2O3 system covering agent to be tested is ≥100g. s The weight of CaO contained in W' CaO =Q s × 1C , containing Al2O3 weight W' Al2O3 =Q s × 1A .

[0051] According to the present invention, the Al2O3 inclusions are adsorbed by the CaO-Al2O3 system covering agent. When saturation is reached, the ratio of CaO to Al2O3 is defined as the calcium-aluminum ratio K, and the calculation formula of the ratio and the temperature of the molten steel in the continuous casting process is shown in formula (II):

[0052] K=-8.195+0.01482×T-5.9497×10 -6 ×T 2 (Ⅱ);

[0053] The determination of the calcium-aluminum ratio K is specifically as follows: the final calcium-aluminum ratio K of the CaO-Al2O3 system covering agent with different initial calcium-aluminum ratios at different temperatures when the Al2O3 inclusions are adsorbed saturated is calculated using thermodynamic calculation software. The results are as follows: Figure 1 As shown by Figure 1It can be seen that the calcium-aluminum ratio K when the covering agent is saturated with inclusion adsorption has nothing to do with the initial calcium-aluminum ratio, but is closely related to the temperature; and as the temperature increases, the calcium-aluminum ratio K decreases continuously when the adsorption is saturated. The K value of the covering agent at different temperatures and different initial calcium-aluminum ratios when the inclusion adsorption is saturated was quadratically fitted. The fitting formula is formula (Ⅱ), and the fitting result is the solid line in the figure. The fitting result is consistent with the thermodynamic calculation result. Formula (Ⅱ) and the covering agent use temperature can be used to quickly calculate and determine the K value. Figure 1 At the same time, the relationship between the theoretical calculated value and the fitting value was compared. The fitting value was consistent with the thermodynamic calculated value, indicating that the fitting formula can be used to accurately calculate and determine K.

[0054] In the present application, the temperature range of T is 1350-1550°C, which also represents the average temperature of the molten steel in the actual continuous casting process and can be detected during the continuous casting process.

[0055] After the CaO-Al2O3 system covering agent is saturated with Al2O3 inclusions, the mass of CaO is conserved, and the Al2O3 weight W at the time of saturated adsorption of the covering agent is obtained by using the calcium-aluminum ratio K at the time of saturated adsorption Al2O3 =W' CaO / K=Q s × 1C / K.

[0056] Since the initial CaO-Al2O3 system covering agent contains Al2O3, the above W Al2O3 It is not the weight of the adsorbed Al2O3 inclusions. The weight of Al2O3 adsorbed when the CaO-Al2O3 coating agent adsorbs Al2O3 inclusions to saturation is Q I =W Al2O3 -W' Al2O3 =Q s ×(w 1C / Kw 1A ), namely Q I It's Q s Substituting the relationship into the expression of I, we get I = w 1C / Kw 1A w 1C / Kw 1A The adsorption capacity of the CaO-Al2O3 system covering agent for Al2O3 inclusions is obtained, which represents the maximum weight of Al2O3 inclusions that can be adsorbed by 1 kg of the CaO-Al2O3 system covering agent.

[0057] The present application also provides the application of the above calculation method in determining the amount of CaO-Al2O3 series covering agent added to the continuous casting tundish. During the continuous casting process, the amount of CaO-Al2O3 series covering agent to be added can be determined according to the amount of inclusions, thereby avoiding the problems caused by adding too much or too little covering agent.

[0058] In order to further understand the present invention, the calculation method of the adsorption capacity of inclusions by the CaO-Al2O3 system covering agent provided by the present invention is described in detail below in conjunction with the examples. The protection scope of the present invention is not limited by the following examples.

[0059] Example IF Calculation of the adsorption capacity of Al2O3 inclusions by CaO-Al2O3 system covering agent in the middle ladle for continuous casting of steel, the pouring temperature of the middle ladle for continuous casting is 1550℃

[0060] (1) Define the adsorption capacity I of CaO-Al2O3 coating agent for Al2O3 inclusions:

[0061]

[0062] In the formula, Q s is the weight of the covering agent before initial use, kg; Q I is the dissolved weight of Al2O3 inclusions when they reach saturation in the covering agent, kg;

[0063] (2) Take 150g of the CaO-Al2O3-based coating agent before initial use and test to determine its CaO and Al2O3 contents, which are w 1C =58.3wt%, w 1A =23.1wt%;

[0064] (3) Thermodynamic calculations show that the ratio of CaO to Al2O3 components (calcium-aluminum ratio K) when the adsorption of Al2O3 inclusions by the CaO-Al2O3 system covering agent reaches saturation is only related to the temperature, but has nothing to do with the calcium-aluminum ratio in the initial covering agent. Therefore, the calcium-aluminum ratio K when the initial covering agent adsorbs Al2O3 inclusions saturated can be determined based on the temperature of the ladle casting process: K = -8.195 + 0.01482 × T - 5.9497 × 10 -6 ×T 2 =-8.1951+0.01482×1550-5.9497×10 -6 ×1550 2 =0.48;

[0065] Where, T is the average temperature of ladle steel during continuous casting, °C;

[0066] (4) Based on steps (2) to (3), calculate the weight Q sThe Al2O3 inclusion adsorption weight Q when the initial covering agent reaches Al2O3 inclusion adsorption saturation I :

[0067] Q I =Q s ×(w 1C / Kw 1A )=Q s ×(58.3% / 0.48-23.1%);

[0068] (5) The Al2O3 inclusion adsorption weight Q determined in step (4) is I Substituting the calculation formula in step (1) into the formula, the adsorption capacity I of the studied CaO-Al2O3 system covering agent for Al2O3 inclusions can be finally determined:

[0069] I=w 1C / Kw 1A =58.3% / 0.48-23.1%=0.98;

[0070] I=1.06, indicating that 1 kg of CaO-Al2O3 coating agent can absorb a maximum of 1.06 kg of Al2O3 inclusions.

[0071] In order to verify the accuracy of the above calculation method, the percentage of CaO and Al2O3 in IF steel continuous casting is w 1C =58.3%, w 1A =23.1% calcium aluminum-based tundish covering agent was tested. The tundish was continuously cast for 10 batches. 160 kg of the calcium aluminum-based tundish covering agent was added to the tundish casting area. The temperature of the tundish covering agent was 1550°C during the continuous casting process. Samples of the tundish covering agent were taken from the casting area for each batch during the casting process to test the composition. The change of the calcium aluminum ratio in the casting area during the casting process was obtained as follows: Figure 2 As shown in the figure, as the number of casting heats increases, Al2O3 in the molten steel continuously floats up into the tundish covering agent, resulting in a continuous decrease in the calcium-aluminum ratio in the covering agent. When the tundish is cast to the seventh heat and subsequent heats, the calcium-aluminum ratio is basically maintained at 0.47 and no longer decreases, indicating that the tundish covering agent has reached saturation in adsorption of Al2O3 inclusions. It can be seen from step (3) of the embodiment that at 1550°C, K=0.48 determined by the formula is in good agreement with the actual measured value of 0.47 during the test process, which verifies the accuracy of the K value calculation formula proposed in this patent.

[0072] Substituting the measured K value of 0.47 into formula (5) can finally determine the measured inclusion adsorption capacity I = = w 1C / Kw 1A =58.3% / 0.47-23.1%=1.01; the measured value 1.01 is in good agreement with the calculated value 0.98, thus verifying the reliability of the calculation method of the present application.

[0073] 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.

[0074] 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 capacity of a CaO-Al2O3 system covering agent for inclusions, comprising the following steps: S1) The adsorption capacity of CaO-Al2O3 system covering agent for Al2O3 inclusions is defined as I, and the calculation formula of I is shown in (Ⅰ): S2) Detect the mass percentage of CaO and Al2O3 in the initial CaO-Al2O3 system covering agent, which are respectively recorded as w 1C 、w 1A , wt%; S3) using the initial CaO-Al2O3 system covering agent to adsorb Al2O3 inclusions, and the ratio of CaO to Al2O3 when saturation is reached is defined as the calcium-aluminum ratio K, and the calculation formula of the ratio and the temperature of the molten steel in the continuous casting process is shown in formula (II): K=-8.195+0.01482×T-5.9497×10 -6 ×T 2 (Ⅱ); S4) After the adsorption is saturated, the weight of Al2O3 inclusions in the CaO-Al2O3 system covering agent is obtained. I Calculate according to formula (III): Q I =W Al2O3 -W’ Al2O3 =Q s ×(w 1C / K-w 1A ) (Ⅲ); S5) combining the calculation formula (III) with the calculation formula (I) to obtain the adsorption capacity I of the CaO-Al2O3 system covering agent for inclusions; Among them, Q s is the initial weight of CaO-Al2O3 system covering agent, kg; Q I is the weight of Al2O3 inclusions when they reach saturation in the covering agent, kg; T is the average temperature of molten steel during continuous casting, °C; W' Al2O3 is the weight of Al2O3 in the initial CaO-Al2O3 system covering agent, kg; W Al2O3 It is the total weight of Al2O3 when the CaO-Al2O3 system covering agent is saturated with adsorption, kg.

2. The calculation method according to claim 1, characterized in that: T is 1350~1550℃.

3. The calculation method according to claim 1, characterized in that: The formula (II) is obtained by the following method: The calcium-aluminum ratios of different initial CaO-Al2O3 system covering agents at different temperatures when Al2O3 inclusions are adsorbed saturated are calculated using thermodynamic calculation software to obtain a curve of the calcium-aluminum ratio and temperature when the covering agent is adsorbed saturated; the calcium-aluminum ratios of the initial CaO-Al2O3 system covering agents are different; The temperature and calcium-aluminum ratio when the covering agent is adsorbed to saturation are fitted.

4. The calculation method according to claim 1, characterized in that: w 1C 30~60wt% 1A It is 10~25wt%.

5. The calculation method according to claim 1, characterized in that: In step S2), the weight of the initial CaO-Al2O3 based covering agent is ≥100 g.

6. The calculation method according to claim 1, characterized in that: The K is 0.3 to 0.

6.

7. The calculation method according to claim 1, characterized in that: Before obtaining the formula (III), it also includes: The CaO-Al2O3 system covering agent is adsorbed to saturation, and the total weight of Al2O3 in the covering agent is W Al2O3 The calculation is carried out according to the following formula: W Al2O3 =W’ CaO / K=Q s ×w 1C / K。 8. Application of the calculation method according to any one of claims 1 to 7 in determining the initial amount of CaO-Al2O3 based covering agent added to the continuous casting tundish.

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