Calculation method for reaction degree of chrome stuffing sand and molten steel and application of calculation method

Abstract

The invention provides a method for calculating the reaction degree of chrome ladle filler sand and molten steel, which comprises the following steps: S1) detecting the weight of the chrome ladle filler sand of a steel ladle, and detecting the content of Cr2O3 in the chrome ladle filler sand; calculating the weight of Cr2O3 in the chrome stuffing sand; detecting the weight of the large ladle molten steel; s2) refining the molten steel, and detecting the content of [Cr] in the molten steel after refining is finished; the refined molten steel is cast, the chrome stuffing sand enters a tundish and is mixed with the molten steel in the tundish, and the content of [Cr] in the molten steel in a tundish casting area is detected; calculating the increment of [Cr] from the end of refining to the tundish molten steel to obtain the weight of Cr2O3 generated by the reaction of the chrome stuffing sand and the molten steel; and S3) defining a reaction index of the chrome stuffing sand and the molten steel and calculating. According to the calculation method provided by the invention, the reaction degree of the chrome stuffing sand and the molten steel is quantitatively calculated based on the addition amount of the chrome stuffing sand and the change of the components of the molten steel, and a key data support is provided for evaluating and optimizing the stuffing sand.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a method for calculating the degree of reaction between chromium drainage sand and molten steel and an application thereof. Background Art

[0002] Drainage sand is an important metallurgical auxiliary material in the iron and steel metallurgical process. It is filled in the water inlet at the bottom of the ladle. During the steel tapping and molten steel transfer process, it plays a blocking role for the water inlet at the bottom of the ladle. When the continuous casting ladle is poured, the drainage sand plays a role in drainage.

[0003] Many researchers have conducted a lot of research and exploration around drainage sand. For example: Chinese patent publication number CN117682878A discloses a drainage sand containing an oxidant and a preparation method thereof, which makes it easier for molten steel to break through the sintering layer under the same static pressure during pouring, thereby realizing automatic pouring; Chinese patent publication number CN117383925A discloses a chromium drainage sand covered with a siliceous coating, which improves the automatic pouring rate by coating the surface of chromium ore sand and plate-shaped corundum with siliceous materials, thereby overcoming the problems of unstable performance and difficulty in pouring of traditional drainage sand; Chinese patent publication number CN115650740A discloses a high-quality magnesium drainage sand for ladle and a preparation method thereof, which has the characteristics of good fluidity, high refractoriness, good high-temperature sintering performance and high self-opening rate; Chinese patent publication number CN117655313A discloses a chromium drainage sand covered with a siliceous coating, which improves the automatic pouring rate by coating the surface of chromium ore sand and plate-shaped corundum with siliceous materials, thereby overcoming the problems of unstable performance and difficulty in pouring of traditional drainage sand; Chinese patent publication number CN115650740A discloses a high-quality magnesium drainage sand for ladle and a preparation method thereof, which has the characteristics of good fluidity, high refractoriness, good high-temperature sintering performance and high self-opening rate; A ladle drainage sand is disclosed, wherein the upper layer is made of chrome sand to ensure high temperature resistance, and the lower layer is made of chrome-free drainage sand, which can reduce the influence of chrome drainage sand on the purity of molten steel in the tundish, thereby reducing the risk of secondary oxidation of molten steel and improving the purity of molten steel; Chinese patent with publication number CN115229172A discloses a high-chromium drainage sand process that can improve the self-opening rate of ladle, which has strong resistance to molten steel corrosion, good resistance to molten steel permeability, good high-temperature sintering performance, uniform particle size distribution, good fluidity, and the automatic pouring rate of ladle can reach more than 99%; Chinese patent with publication number CN117326875A provides a high-alloy steel refined ladle zirconium drainage sand and a preparation method thereof, which reduces the reactivity of drainage sand with molten steel by using ZrO2 instead of traditional Cr2O3 in drainage sand.

[0004] Chromium drainage sand is the most widely used type of drainage sand, and Cr2O3 is one of its main components. When the ladle is poured, the Cr2O3 in the drainage sand is mixed with the molten steel into the tundish and reacts with active alloying elements such as [Al] and [Ti] in the molten steel ([Al]+Cr2O3→Al2O3+[Cr], [Ti]+Cr2O3→TiO2+[Cr]), resulting in secondary oxidation pollution of the molten steel and affecting the cleanliness of the molten steel. Quantitative calculation of the degree of reaction between chromium drainage sand and molten steel is an important indicator for evaluating its effect on secondary oxidation pollution of molten steel, and can also provide key data support for optimizing the composition, particle size and other parameters of drainage sand, thereby reducing its reactivity with molten steel. However, current technology mainly proposes corresponding methods for optimizing the design of drainage sand composition, and does not involve quantitative evaluation and calculation methods for the reactivity of chromium drainage sand with molten steel. Summary of the invention

[0005] The technical problem solved by the present invention is to provide a method for calculating the degree of reaction between chromium drainage sand and molten steel. The calculation method provided by the present application can quantitatively and accurately calculate the degree of reaction between chromium drainage sand and molten steel.

[0006] In view of this, the present application provides a method for calculating the degree of reaction between chromium drainage sand and molten steel, comprising the following steps:

[0007] S1) Detect the weight of the chromium drainage sand of the ladle, recorded as W1, kg, and detect the content of Cr2O3 in the chromium drainage sand, recorded as w' Cr2O3 , wt%; calculate the weight of Cr2O3 in the chromium drainage sand, recorded as W3, W3 = W1 × w' Cr2O3 , kg;

[0008] Detect the weight of the ladle of molten steel, recorded as W2, t;

[0009] S2) The molten steel is refined, and the [Cr] content in the molten steel at the end of refining is detected and recorded as w Cr1 , wt%;

[0010] The refined molten steel is poured, and the chromium drainage sand enters the tundish and mixes with the molten steel in the tundish. The [Cr] content in the molten steel in the casting area of ​​the tundish is detected and recorded as w Cr2 , wt%;

[0011] Calculate the increment of [Cr] in the molten steel from the end of refining to the tundish, recorded as Δ[Cr], Δ[Cr] = W2×1000×(w Cr2 -w Cr1 ), kg, then the weight of Cr2O3 produced by the reaction of the chromium drainage sand and molten steel is obtained, which is recorded as W4, W4 = Δ[Cr] × 1.46, kg;

[0012] S3) defining the reaction index R of the chromium drainage sand and molten steel I , R I =W4 / W3×100%.

[0013] Preferably, in step S1), in the process of detecting the content of Cr2O3 in the chromium drainage sand, the detected amount of the chromium drainage sand is ≥100g.

[0014] Preferably, in step S1), in the process of detecting the content of Cr2O3 in the chromium drainage sand, the detected amount of the chromium drainage sand is 200-300g.

[0015] Preferably, the timing for detecting the [Cr] content in the molten steel in the ladle casting area is when the weight of the molten steel cast in the ladle is 70-80% of the weight of the molten steel in the ladle.

[0016] Preferably, during the pouring process, the active metal elements [M] in the molten steel react with Cr2O3 in the chromium drainage sand.

[0017] Preferably, the refining is vacuum refining RH, and the refining also includes a converter LD before the refining.

[0018] Preferably, in step S1), the content of Cr2O3 in the chromium drainage sand is 20-40wt%.

[0019] The present application also provides the application of the calculation method in the design of chrome drainage sand.

[0020] The present application provides a method for calculating the degree of reaction between chromium drainage sand and molten steel, which first detects the weight of chromium drainage sand in a ladle and the content of Cr2O3 in the chromium drainage sand, and calculates the weight of Cr2O3 in the chromium drainage sand; at the same time, detects the weight of molten steel in a large ladle; then refines the molten steel, and detects the [Cr] content in the molten steel at the end of refining; then pours the refined molten steel, and the chromium drainage sand enters the tundish and mixes with the molten steel in the tundish, and then detects the [Cr] content in the molten steel in the casting area of ​​the tundish; calculates the increment of [Cr] in the molten steel from the end of molten steel refining to the end of molten steel refining; finally, calculates the degree of reaction between the chromium drainage sand and the molten steel based on the above results, and uses R I The calculation method provided in this application quantitatively calculates the degree of reaction between chromium drainage sand and molten steel based on the amount of chromium drainage sand added and the change in the composition of molten steel, providing key data support for the evaluation and optimization of drainage sand. DETAILED DESCRIPTION

[0021] 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.

[0022] In view of the lack of a quantitative calculation method for the degree of reaction between chromium drainage sand and molten steel in the prior art, the present application provides a method for calculating the degree of reaction between chromium drainage sand and molten steel, which quantitatively calculates the degree of reaction between chromium drainage sand and molten steel based on the filling amount of chromium drainage sand and the changes in the composition of the molten steel process without affecting normal production, and provides key data support for the evaluation and optimization of chromium drainage sand. Specifically, an embodiment of the present invention discloses a method for calculating the degree of reaction between chromium drainage sand and molten steel, comprising the following steps:

[0023] S1) Detect the weight of the chromium drainage sand of the ladle, recorded as W1, kg, and detect the content of Cr2O3 in the chromium drainage sand, recorded as w' Cr2O3 , wt%; calculate the weight of Cr2O3 in the chromium drainage sand, recorded as W3, W3 = W1 × w' Cr2O3 , kg;

[0024] Detect the weight of the ladle of molten steel, recorded as W2, t;

[0025] S2) The molten steel is refined, and the [Cr] content in the molten steel at the end of refining is detected and recorded as w Cr1 , wt%;

[0026] The refined molten steel is poured, and the chromium drainage sand enters the tundish and mixes with the molten steel in the tundish. The [Cr] content in the molten steel in the casting area of ​​the tundish is detected and recorded as w Cr2 , wt%;

[0027] Calculate the increment of [Cr] in the molten steel from the end of refining to the tundish, recorded as Δ[Cr], Δ[Cr] = W2×1000×(w Cr2 -w Cr1 ), kg, then the weight of Cr2O3 produced by the reaction of the chromium drainage sand and molten steel is recorded as W4, W4 = Δ[Cr] × 1.46, kg;

[0028] S3) defining the reaction index R of the chromium drainage sand and molten steel I , R I =W4 / W3×100%.

[0029] The method for calculating the degree of reaction between chromium drainage sand and molten steel provided in the present application is for calculation during the steel casting process, and is applicable to all types of steel that require the introduction of chromium drainage sand during the continuous casting process. For example, the type of steel can be selected from ultra-low carbon steel.

[0030] In the method for calculating the degree of reaction between chromium drainage sand and molten steel, the present application first detects the weight of chromium drainage sand in the ladle, recorded as W1, kg, and detects the content of Cr2O3 in the chromium drainage sand, recorded as w' Cr2O3, wt%; in the process of detecting the content of Cr2O3 in the chromium drainage sand, the detected amount of the chromium drainage sand is ≥100g, specifically, the detected amount of the chromium drainage sand is 100-200g. The present application preferably detects the content of Cr2O3 in part of the chromium drainage sand, which can characterize the content of Cr2O3 in the chromium drainage sand in the ladle. On this basis, the weight of Cr2O3 in the chromium drainage sand is calculated, recorded as W3, W3=W1×w' Cr2O3 In the process of continuous casting, all refractory materials do not contain Cr element, and only Cr2O3 in chromium drainage sand reacts with molten steel. Therefore, the change of Cr2O3 can characterize the degree of reaction between chromium drainage sand and molten steel.

[0031] This application also detects the weight of the ladle of molten steel, which is recorded as W2,t.

[0032] According to the present invention, the molten steel is refined, and the [Cr] content in the molten steel at the end of the refining is detected and recorded as w Cr1 , wt%; the above detection is also to detect part of the molten steel sample, and the end of refining is specifically the end of the last refining process before continuous casting. Afterwards, the refined molten steel is transferred from the large ladle to the medium ladle for pouring. During this process, the chromium drainage sand enters the medium ladle and mixes with the molten steel in the medium ladle, that is, the chromium drainage sand reacts with the active metal elements in the molten steel; when the weight of the cast molten steel in the large ladle is 70-80% of the weight of the molten steel in the large ladle, a molten steel sample is taken from the casting area of ​​the medium ladle to detect the [Cr] content therein, which is recorded as w Cr2 , wt%. Based on this, the increment of [Cr] during the process from the end of molten steel refining to the tundish molten steel is calculated, which is recorded as Δ[Cr], Δ[Cr] = W2×1000×(w Cr2 -w Cr1 ), kg.

[0033] During the process of pouring from the large ladle to the medium ladle, the drainage sand enters the medium ladle and mixes with the molten steel in the medium ladle. In this process, the active metal elements [M] in the molten steel react with the Cr2O3 in the chromium drainage sand, x[M]+yCr2O3→M x O 3y +2y[Cr],M x O 3y That is, the non-metallic oxide inclusions formed, and [Cr] is the [Cr] element that enters the molten steel after the Cr2O3 in the drainage sand reacts with the molten steel; based on Δ[Cr], the weight of Cr2O3 in the drainage sand that reacts with the molten steel can be calculated to determine W4=Δ[Cr]×1.46, kg, wherein 1.46 is obtained because the atomic weight of Cr is 52, and the atomic weight of Cr2O3 is 152, then 152 / (52×2)=1.46.

[0034] This application finally defines the reaction index R of chromium drainage sand and molten steel I , R I =W4 / W3×100%, this reaction index can reflect the reaction degree between chromium drainage sand and molten steel.

[0035] The present application also provides an application of the above-mentioned calculation method in the design of chromium drainage sand; the chromium drainage sand design can be the design of the composition of the chromium drainage sand, or the design of the particle size of the chromium drainage sand, and the present application does not impose any special restrictions on this; for example, according to the calculated degree of reaction between the chromium drainage sand and molten steel, the composition of the chromium drainage sand can be adjusted to allow as many impurity metal elements in the molten steel as possible to react with the chromium drainage sand, thereby ensuring the purity of the molten steel.

[0036] The present invention provides a method for calculating the degree of reaction between chromium drainage sand and molten steel, which can provide key data support for optimizing the particle size and composition of drainage sand, reducing the secondary oxidation pollution of chromium drainage sand on molten steel, improving the cleanliness of molten steel, and reducing the quality defects of steel inclusions; the present invention is conducive to improving the cleanliness of molten steel of varieties of steel such as automobile panels, reducing the inclusion degradation rate, and is expected to create an annual benefit of at least 500,000 yuan. The calculation method can be promoted and applied in the industry.

[0037] In order to further understand the present invention, the calculation method of the reaction degree between the chromium drainage sand and molten steel provided by the present invention is described in detail below in conjunction with the embodiments. The protection scope of the present invention is not limited by the following embodiments.

[0038] Example: Calculation of the reaction index between chromium drainage sand and molten steel in the process of producing ultra-low carbon steel in the converter LD → vacuum RH → continuous casting CC process

[0039] (1) Based on industrial production, the process parameters are determined, including the filling weight of the chromium drainage sand in the ladle W1 = 50 kg, the weight of the molten steel in the large ladle W2 = 220 t, and the weight of the molten steel in the medium ladle W 中 =70t;

[0040] (2) Take 200g of the filled drainage sand and test to determine the Cr2O3 content w' Cr2O3 = 35.8%; Calculate the weight of Cr2O3 contained in the drainage sand filled W3 = W1 × w' Cr2O3 =50kg×35.8%=17.9kg;

[0041] (3) Take a sample of molten steel (racket sample) at the end of RH and test the content of [Cr] in it. Cr1 =0.025%;

[0042] (4) During the continuous casting process, when the weight of the molten steel poured into the ladle reaches 160 tons, a molten steel sample (racket sample) is taken from the casting area of ​​the tundish to detect the [Cr] content wCr2 =0.027%;

[0043] (5) Calculate the weight increase of molten steel [Cr] from the end of RH to the middle package Δ [Cr] = W2 × 1000 × (w Cr2 -w Cr1 )=220×1000×(0.027%-0.025%)=4.4kg;

[0044] (6) After the ladle is poured, the drainage sand enters the tundish and mixes with the molten steel in the tundish. During this process, the active metal elements [M] in the molten steel react with the Cr2O3 in the chromium drainage sand to form x[M]+yCr2O3→M x O 3y +2y[Cr],M x O 3y is the non-metallic oxide inclusion formed, and [Cr] is the [Cr] element that enters the molten steel after the Cr2O3 in the drainage sand reacts with the molten steel; therefore, based on Δ[Cr] in step (5), the weight of Cr2O3 in the drainage sand that reacts with the molten steel can be calculated to determine W4=Δ[Cr]×1.46=4.4kg×1.46=6.4kg;

[0045] (7) Reaction index R of chromium drainage sand and molten steel I =W4 / W3×100%=6.4kg / 17.9kg×100%=36%, i.e., 36% of the chromium drainage sand reacts with the molten steel.

[0046] 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.

[0047] 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 degree of reaction between chromium drainage sand and molten steel, comprising the following steps: S1) Detect the weight of the chromium drainage sand of the ladle, recorded as W1, kg, and detect the content of Cr2O3 in the chromium drainage sand, recorded as w' Cr2O3 , wt%; calculate the weight of Cr2O3 in the chromium drainage sand, recorded as W3, W3 = W1 × w' Cr2O3 , kg; Detect the weight of the ladle of molten steel, recorded as W2, t; S2) The molten steel is refined, and the [Cr] content in the molten steel at the end of refining is detected and recorded as w Cr1 , wt%; The refined molten steel is poured, and the chromium drainage sand enters the tundish and mixes with the molten steel in the tundish. The [Cr] content in the molten steel in the casting area of ​​the tundish is detected and recorded as w Cr2 , wt%; Calculate the increment of [Cr] in the molten steel from the end of refining to the tundish, recorded as Δ[Cr], Δ[Cr] = W2×1000×(w Cr2 -w Cr1 ), kg, then the weight of Cr2O3 produced by the reaction of the chromium drainage sand and molten steel is obtained, which is recorded as W4, W4 = Δ[Cr] × 1.46, kg; S3) defining the reaction index R of the chromium drainage sand and molten steel I , R I =W4 / W3×100%.

2. The calculation method according to claim 1, characterized in that: In step S1), in the process of detecting the content of Cr2O3 in the chromium drainage sand, the detected amount of the chromium drainage sand is ≥100g.

3. The calculation method according to claim 1 or 2, characterized in that: In step S1), in the process of detecting the content of Cr2O3 in the chromium drainage sand, the detected amount of the chromium drainage sand is 200-300g.

4. The calculation method according to claim 1, characterized in that: The timing for detecting the [Cr] content in the molten steel in the ladle casting area is when the weight of the molten steel cast in the ladle is 70-80% of the weight of the molten steel in the ladle.

5. The calculation method according to claim 1, characterized in that: During the pouring process, the active metal elements [M] in the molten steel react with Cr2O3 in the chromium drainage sand.

6. The calculation method according to claim 1, characterized in that: The refining is vacuum refining RH, and the refining also includes a converter LD before the refining.

7. The calculation method according to claim 1, characterized in that: In step S1), the content of Cr2O3 in the chromium drainage sand is 20-40wt%.

8. Application of the calculation method according to any one of claims 1 to 7 in the design of chrome drainage sand.