Low-titanium refining slag and preparation method thereof

Abstract

The invention discloses low-titanium refining slag and a preparation method thereof, and the low-titanium refining slag comprises the following components in percentage by mass: 35%-60% of CaO, 5%-10% of MgO, 15%-30% of SiO2, 10%-15% of Al2O3, 3%-8% of B2O3, 2%-5% of Y2O3, 1%-3% of K2O and 0.01%-0.2% of TiO2. The method is designed on the basis of a CaO-MgO-SiO2-Al2O3 quaternary refining slag system, the refining slag is controlled to be 1.50-2.50 low alkalinity, a small amount of rare earth Y2O3 and B2O3 are introduced to jointly regulate and control the melting characteristic and rheological characteristic of the refining slag, the steel slag reaction is optimized, under the action of K2O, the refining slag is applied to refining of molten steel after LF refining is finished, oxygen and sulfur can be effectively removed, and the steel slag refining quality is improved. And meanwhile, the catalyst also has relatively good removal performance on phosphorus.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a low-titanium refined slag and a preparation method thereof. Background Art

[0002] With the increasingly good development of the steel industry, there are not only requirements for output, but also higher and higher quality requirements. Furnace refining is one of the most important links in the process of steel production. In order to pursue stable quality when producing steel products, choosing suitable steelmaking refining slag is conducive to improving the refining effect and optimizing the production process. The composition and characteristics of the refining slag have the greatest impact on the refining effect. Therefore, studying the performance of refining slag is of great significance for the actual industrial production and the role of refining equipment.

[0003] Traditional refining slag systems include CaO-Al 2 O 3 Slag system, CaO-CaF 2 Slag system and CaO-Al 2 O 3 -CaF 2 Slag system. At present, in order to increase the application of tailings produced by steelmaking, some methods use tailings as materials for refining slag. For example, CN117701894A discloses a method for preparing calcium aluminate refining slag and its application. The ratio of this refining slag is: 50-60% calcium aluminate, 10-30% alumina, and 5-20% limestone. The use of limestone as a solvent can reduce the melting point of calcium aluminate refining slag, thereby reducing the required heating energy, and thus helping to reduce energy consumption and production costs. However, this method does not evaluate the deoxidation and desulfurization properties of the refining slag. There are also some methods that introduce rare earth oxides into the refining slag system. For example, CN117305610A discloses a low-basicity fluorine-free rare earth refining slag for clean SWRS82B steel production and its preparation method and application. By mass percentage, it consists of 33-41% CaO, 13-15% Al 2 O 3 , 23~37% SiO 2 , 3-7% CeO 2 , 7-9% MgO composition, the addition of appropriate amount of rare earth oxides can improve the melting characteristics and rheological properties of the refined slag, ensuring that the slag is slag-free as early as possible during the refining process. 2 The higher the content, the higher the cost.

[0004] It is still necessary to regulate the composition and proportion of refined slag to obtain refined slag with good desulfurization performance. Summary of the invention

[0005] In order to overcome the problems existing in the prior art, the present invention provides a low-titanium refined slag, which comprises, by mass percentage,

[0006] 35% to 60% CaO, 5% to 10% MgO, 15% to 30% SiO 2 10% to 15% Al 2 O 3 3% to 8% B 2 O 3 , 2% to 5% Y 2 O 3 1%~3% K 2 O, 0.01% to 0.2% TiO 2 .

[0007] The low titanium refined slag of the present invention adopts CaO-MgO-SiO 2 -Al 2 O 3 Quaternary refining slag system, in which CaO and MgO react in the slag to precipitate O 2- The oxides of SiO are basic oxides; 2 etc. react in the slag to combine with O 2- The oxides of Al are acidic oxides; 2 O 3 The acidity and alkalinity of MgO changes with the change of valence, and it is an amphoteric oxide. It is generally believed that the CaO content in the refined slag is the key to desulfurization. A high content is conducive to desulfurization, but the increase of CaO content will lead to an increase in basicity, thereby increasing the viscosity and melting point, and the fluidity of the refined slag will become worse, which will have an adverse effect on desulfurization. The role of MgO is similar to that of CaO, but the desulfurization effect is not as good as CaO, and the ratio should not be too high. Al 2 O 3 With the increase of content, the melting point and viscosity gradually decrease, which improves the fluidity of the refined slag.

[0008] Traditionally, CaF is added to the refined slag to obtain better fluidity. 2 , but CaF 2 It will corrode the furnace lining and reduce the service life of the equipment. In addition, because the slag contains fluorine, it is highly volatile at high temperatures and will harm the health of on-site operators. Therefore, it is necessary to avoid CaF 2 Currently, some studies have used B 2 O 3 As a new type of metallurgical slag flux, it is used in continuous casting protection slag to improve the fluidity and viscosity of the refined slag, so that the refined slag can be slaged earlier, creating good kinetic conditions for the steel slag reaction. 2 O 3, in order to improve the performance of refined slag.

[0009] Rare earth elements are very easy to combine with sulfur and oxygen elements to form inclusions, which are then removed and have the characteristics of purifying molten steel. The desulfurization ability of rare earth elements is between magnesium and calcium. They combine with sulfur to form rare earth sulfides. This type of inclusion is easy to be discharged from the molten steel, but if the rare earth content is too high compared to the sulfur content that can be combined, desulfurization will be inhibited. 2 O 3 The mass ratio of CaO-MgO-SiO 2 -Al 2 O 3 The quaternary refined slag system can better remove sulfur and oxygen elements.

[0010] The present invention also introduces a small amount of K 2 O has a better effect on the removal of sulfur in the presence of other components, and also significantly improves the removal of phosphorus.

[0011] Furthermore, the K 2 The mass percentage of O is 2%, B 2 O 3 and Y 2 O 3 The mass ratio is 1.5-2.0:1.

[0012] Refining slag mainly controls the basicity of slag to achieve the purpose of controlling the total oxygen in molten steel. 2 O 3 Easy to form liquid (CaO) x (Al 2 O 3 ) y The slag has an increased ability to absorb oxide inclusions. 2 ) increases, the effective content in the slag increases, the desulfurization rate increases, and the slag also has a high deoxidation potential. However, SiO 2 The proportion of aluminum is too high, aluminum deoxidation cannot be fully utilized, and the deoxidation product Al 2 O 3 It may be retained in the steel, affecting the purity of the molten steel. Therefore, the basicity of the refined slag is also a very important control factor. The basicity calculation formula of the present invention is (CaO+MgO) / (SiO 2 +Al 2 O 3 ), while designing for lower alkalinity.

[0013] Titanium can play a role in desulfurization, alloying, nitrogen fixation and grain refinement in the steelmaking process. The content of titanium element in the present invention is relatively small, and the overall effect is not obvious.

[0014] Furthermore, the basicity of the refined slag is 1.50-2.50.

[0015] Furthermore, the basicity of the refined slag is 1.70-2.20.

[0016] Furthermore, the particle size of the refined slag is 20 to 50 mm.

[0017] The present invention also provides a method for preparing the above-mentioned low-titanium refined slag, comprising:

[0018] The raw materials are obtained according to a mass ratio and mixed, then heated to melt, and cooled to obtain low-titanium refined slag.

[0019] Furthermore, the heating and melting is continued at 1500-1590° C. for 20-30 minutes.

[0020] The slag treatment process after steelmaking is commonly used in the electric furnace process and the converter process, namely: steelmaking from an electric arc furnace or converter → LF (Ladle Furnace, ladle refining) furnace refining (adding aluminum, slag, Ca-Si or slag modifying agent) → casting. LF furnace refining is one of the main methods of refining outside the furnace, and its key lies in the rapid production of white slag. The purpose of LF slag making is to desulfurize, deoxidize, improve alloy yield, and remove inclusions.

[0021] The present invention also provides the application of the above-mentioned low-titanium refined slag in alloy steel production, including:

[0022] The low-titanium refined slag is added to the molten steel after LF refining, and then kept warm, and then cast to obtain an ingot.

[0023] Furthermore, the addition amount of the low-titanium refined slag is 2-5 kg ​​per ton of molten steel.

[0024] Furthermore, the temperature of the molten steel is 1590-1620°C;

[0025] The insulation time is 30 to 60 minutes.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention is based on CaO-MgO-SiO 2 -Al 2 O 3 The quaternary refining slag system is designed to control the refining slag to a relatively low basicity of 1.50 to 2.50, and a small amount of rare earth Y is introduced. 2 O 3 With B 2 O 3 The melting characteristics and rheological properties of the refined slag were jointly regulated to optimize the slag reaction.2 Under the action of O, the refining slag is applied to the refining of molten steel after LF refining, which can effectively remove oxygen and sulfur, and also has good removal performance for phosphorus. The low-titanium refining slag of the present invention has simple composition, good effect, and has the potential to be applied to alloy steel production. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 A photograph of low titanium refined slag prepared in Example 1 of the present invention is shown. DETAILED DESCRIPTION

[0030] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0031] The following will be combined with the specific embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] A method for preparing low-titanium refined slag, comprising the following steps:

[0034] S1. Weigh 48.97% CaO, 7% MgO, and 22% SiO by mass. 2 , 13% Al 2 O 3 5% B 2 O 3 , 3% Y 2 O 3 , 1% K 2 O, 0.03% TiO 2 , basicity is about 1.60;

[0035] S2, mixing the raw materials of step S1, then heating to 1550° C. to melt for 25 min, and then water cooling to obtain original slag;

[0036] S3, crushing and sieving the original slag obtained in step S2 to obtain low-titanium refined slag with a particle size of 20 to 50 mm, such as Figure 1 shown.

[0037] Example 2

[0038] A method for preparing low-titanium refined slag, comprising the following steps:

[0039] S1. Weigh 50.97% CaO, 10% MgO, and 20% SiO by mass. 2 , 10% Al 2 O 3 5% B 2 O 3 , 3% Y 2 O 3 , 1% K 2 O, 0.03% TiO 2 , basicity is about 2.03;

[0040] S2, mixing the raw materials of step S1, then heating to 1550° C. to melt for 25 min, and then water cooling to obtain original slag;

[0041] S3, crushing and sieving the original slag obtained in step S2 to obtain low-titanium refined slag with a particle size of 20 to 50 mm.

[0042] Example 3

[0043] A method for preparing low-titanium refined slag, comprising the following steps:

[0044] S1. Weigh 54.97% CaO, 10% MgO, and 16% SiO by mass. 2 , 10% Al 2 O 3 5% B 2 O 3 , 3% Y 2 O 3 , 1% K 2 O, 0.03% TiO 2 , alkalinity is about 2.50;

[0045] S2, mixing the raw materials of step S1, then heating to 1550° C. to melt for 25 min, and then water cooling to obtain original slag;

[0046] S3, crushing and sieving the original slag obtained in step S2 to obtain low-titanium refined slag with a particle size of 20 to 50 mm.

[0047] Example 4

[0048] A method for preparing low-titanium refined slag, comprising the following steps:

[0049] S1. Weigh 48.97% CaO, 7% MgO, and 21% SiO by mass. 2 , 13% Al 2 O 3 5% B 2 O 3 , 3% Y 2 O 3 , 2% K 2 O, 0.03% TiO 2 , basicity is about 1.65;

[0050] S2, mixing the raw materials of step S1, then heating to 1550° C. to melt for 25 min, and then water cooling to obtain original slag;

[0051] S3, crushing and sieving the original slag obtained in step S2 to obtain low-titanium refined slag with a particle size of 20 to 50 mm.

[0052] Example 5

[0053] A method for preparing low-titanium refined slag, comprising the following steps:

[0054] S1. Weigh 50.97% CaO, 8% MgO, and 20% SiO by mass. 2 , 11% Al 2 O 3 5% B 2 O 3 , 3% Y 2 O 3 , 2% K 2 O, 0.03% TiO 2 , basicity is about 1.90;

[0055] S2, mixing the raw materials of step S1, then heating to 1550° C. to melt for 25 min, and then water cooling to obtain original slag;

[0056] S3, crushing and sieving the original slag obtained in step S2 to obtain low-titanium refined slag with a particle size of 20 to 50 mm.

[0057] Example 6

[0058] A method for preparing low-titanium refined slag, comprising the following steps:

[0059] S1. Weigh 52.97% CaO, 10% MgO, and 17% SiO by mass.2 , 10% Al 2 O 3 5% B 2 O 3 , 3% Y 2 O 3 , 2% K 2 O, 0.03% TiO 2 , basicity is about 2.33;

[0060] S2, mixing the raw materials of step S1, then heating to 1550° C. to melt for 25 min, and then water cooling to obtain original slag;

[0061] S3, crushing and sieving the original slag obtained in step S2 to obtain low-titanium refined slag with a particle size of 20 to 50 mm.

[0062] Example 7

[0063] A method for preparing low-titanium refined slag, comprising the following steps:

[0064] S1. Weigh 46.97% CaO, 7% MgO, and 22% SiO by mass. 2 , 13% Al 2 O 3 5% B 2 O 3 , 3% Y 2 O 3 , 3% K 2 O, 0.03% TiO 2 , basicity is about 1.54;

[0065] S2, mixing the raw materials of step S1, then heating to 1550° C. to melt for 25 min, and then water cooling to obtain original slag;

[0066] S3, crushing and sieving the original slag obtained in step S2 to obtain low-titanium refined slag with a particle size of 20 to 50 mm.

[0067] Example 8

[0068] A method for preparing low-titanium refined slag, comprising the following steps:

[0069] S1. Weigh 50.97% CaO, 7% MgO, and 20% SiO by mass. 2 , 11% Al 2 O 3 5% B 2 O 3 , 3% Y 2 O 3 , 3% K 2O, 0.03% TiO 2 , basicity is about 1.87;

[0070] S2, mixing the raw materials of step S1, then heating to 1550° C. to melt for 25 min, and then water cooling to obtain original slag;

[0071] S3, crushing and sieving the original slag obtained in step S2 to obtain low-titanium refined slag with a particle size of 20 to 50 mm.

[0072] Example 9

[0073] A method for preparing low-titanium refined slag, comprising the following steps:

[0074] S1. Weigh 54.97% CaO, 7% MgO, and 16% SiO by mass. 2 , 11% Al 2 O 3 5% B 2 O 3 , 3% Y 2 O 3 , 3% K 2 O, 0.03% TiO 2 , basicity is about 2.30;

[0075] S2, mixing the raw materials of step S1, then heating to 1550° C. to melt for 25 min, and then water cooling to obtain original slag;

[0076] S3, crushing and sieving the original slag obtained in step S2 to obtain low-titanium refined slag with a particle size of 20 to 50 mm.

[0077] Comparative Example 1

[0078] Compared with Example 5, the difference is that in step S1, 52.3% CaO, 8% MgO, 20.67% SiO 2 , 11% Al 2 O 3 5% B 2 O 3 , 3% Y 2 O 3 , 0.03% TiO 2 , the alkalinity is about 1.90.

[0079] Comparative Example 2

[0080] Compared with Example 5, the difference is that in step S1, 56.25% of CaO, 8% of MgO, and 22.72% of SiO are weighed by mass percentage. 2 , 11% Al 2O 3 , 2% K 2 O, 0.03% TiO 2 , the alkalinity is about 1.90.

[0081] Comparative Example 3

[0082] Compared with Example 5, the difference is that in step S1, 50.97% CaO, 8% MgO, 20% SiO 2 , 11% Al 2 O 3 8% B 2 O 3 , 2% K 2 O, 0.03% TiO 2 , the alkalinity is about 1.90.

[0083] Comparative Example 4

[0084] Compared with Example 5, the difference is that in step S1, 50.97% CaO, 8% MgO, 20% SiO 2 , 11% Al 2 O 3 , 8% Y 2 O 3 , 2% K 2 O, 0.03% TiO 2 , the alkalinity is about 1.90.

[0085] Comparative Example 5

[0086] Compared with Example 5, the difference is that: 50.97% CaO, 8% MgO, 20% SiO 2 , 11% Al 2 O 3 3% B 2 O 3 , 5% Y 2 O 3 , 2% K 2 O, 0.03% TiO 2 , the alkalinity is about 1.90.

[0087] Table 1 summarizes the proportion information of the low titanium refined slag of the above examples and comparative examples.

[0088] Table 1 Proportion of low titanium refined slag

[0089]

[0090]

[0091] Test Case

[0092] The melting temperature and viscosity of low-titanium refined slag are measured using a melt property tester. For the temperature test, 10g of low-titanium refined slag is pressed into a cylinder, then placed on a corundum sheet and placed in a melt property tester for measurement. For the viscosity test, 150g of low-titanium refined slag is placed in a graphite crucible and placed in the furnace body of the melt property tester, placed in the heating high temperature zone in the corundum tube, and the instrument heating program is started. After the temperature is raised to 1600°C, it is kept warm for 30 minutes to ensure complete melting. After that, the heating furnace body is raised, and the test head is inserted into the molten slag and kept warm for 10 minutes before starting the viscosity measurement. The melting temperature and viscosity test results are shown in Table 2.

[0093] Table 2 Melting temperature and viscosity test results

[0094]

[0095]

[0096] From Table 2, Comparative Example 2 has the highest melting point and viscosity. This is because the CaO content is relatively high. In the absence of flux, a large amount of CaO compounds and substances with high melting points such as dicalcium silicate are produced. The test results of Example 5 and Comparative Examples 2-4 show that under the same basicity, adding B 2 O 3 and / or Y 2 O 3 It can reduce the melting point of refined slag, because B 2 O 3 The melting point is low, and B 2 O 3 Can be used with CaO, MgO, SiO 2 The oxide components react to form low melting point substances; rare earth oxide Y 2 O 3 The addition of can improve the melting characteristics and rheological properties of the refined slag. The other components of Example 5 and Comparative Example 5 are the same, B 2 O 3 The proportion is larger, and the melting point and viscosity are further reduced.

[0097] At 1600°C, 3 kg of low titanium refining slag prepared in the embodiment and the comparative example was added to the molten steel after LF refining, and then kept warm for 45 minutes. During this period, the contents of oxygen, sulfur and phosphorus in the initial molten steel and the molten steel after keeping warm were tested, and the deoxidation rate, desulfurization rate and dephosphorization rate were calculated. The results are shown in Table 3.

[0098] Table 3 Impurity element removal results

[0099]

[0100]

[0101] From the test results in Table 3, it can be seen that Examples 4-6 of the present invention have a good removal rate of oxygen, sulfur and phosphorus in molten steel, with a removal rate of >55%. 2 O 3 and Y 2 O 3 The impurity removal performance of Comparative Example 2 is the worst, because the melting characteristics and rheological properties of the refined slag are the worst. Compared with Example 5, Comparative Example 1 does not contain K 2 O, the desulfurization and desulfurization effects are significantly reduced. Compared with Example 5, only a higher content of Y 2 O 3 Without B 2 O 3 The deoxidation and desulfurization performance of Comparative Example 4 is significantly reduced. This is because the density of rare earth element Y combined with oxygen is large, and the inclusion product is not easy to float up; although Y combines with sulfur to form rare earth sulfide at low concentrations, this type of inclusion is easy to be discharged from the molten steel, but when the rare earth content is too high compared to the sulfur content that can be combined, desulfurization will be inhibited. Compared with Example 5, B in Comparative Example 5 2 O 3 and Y 2 O 3 The quality of the deoxidation and desulfurization is relatively low, but the dephosphorization performance is significantly reduced. These results show that under similar alkalinity, adding K 2 O and adjust B 2 O 3 and Y 2 O 3 The mass ratio of can enhance the interaction between low titanium refined slag and molten steel, thereby significantly improving the deoxidation, desulfurization and dephosphorization effects.

[0102] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A low-titanium refined slag, characterized in that: In percentage by mass, including: 35%~60% CaO, 5%~10% MgO, 15%~30% SiO2, 10%~15% Al2O3, 3%~8% B2O3, 2%~5% Y2O3, 1%~3% K2O, 0.01%~0.2% TiO2.

2. The low titanium refined slag according to claim 1, characterized in that: The mass percentage of Ka2O is 2%, and the mass ratio of B2O3 to Y2O3 is 1.5-2.0:

1.

3. The low titanium refined slag according to claim 1, characterized in that: The basicity of the refined slag is 1.50-2.

50.

4. The low titanium refined slag according to claim 1, characterized in that: The basicity of the refined slag is 1.70-2.

20.

5. The low-titanium refined slag according to any one of claims 1 to 4, characterized in that: The particle size of the refined slag is 20-50 mm.

6. A method for preparing low-titanium refined slag according to any one of claims 1 to 5, characterized in that: include, The raw materials are obtained according to a mass ratio and mixed, then heated to melt, and cooled to obtain low-titanium refined slag.

7. The method for preparing low-titanium refined slag according to claim 6, characterized in that: The heating and melting is continued at 1500-1590° C. for 20-30 minutes.

8. An application of the low-titanium refined slag as claimed in any one of claims 1 to 5 in alloy steel production, characterized in that: include, The low-titanium refined slag is added to the molten steel after LF refining, and then kept warm, and then cast to obtain an ingot.

9. The use according to claim 8, characterized in that: The addition amount of the low-titanium refined slag is 2-5 kg ​​per ton of molten steel.

10. The use according to claim 8, characterized in that: The temperature of the molten steel is 1590-1620°C; The insulation time is 30 to 60 minutes.

Images