Titanium-containing continuous casting protective mold flux

Abstract

The application relates to a continuous casting protective slag, in particular a titanium-containing continuous casting protective slag. The mass percentage of the component ingredients is as follows: MgO: 4-7%; CaO: 35-40%; SiO2: 20-28%; TiO2: 4-6%; Al2O3: 7-10%; K2O: 3-5%; BaO: 4-7%; Pr6O 11 : 2-4%; C: 3-4%; and the rest is inevitable impurities. The application replaces the fluoride in the traditional protective slag with TiO2, realizes the environmental protection function type protective slag of fluoride-free protective slag while ensuring the reduction of viscosity and the control of heat transfer. The rare earth compound Pr6O 11 is added at the same time to consume excessive Ti 4+ ions in the protective slag system and avoid the phenomenon of excessively high comprehensive alkalinity.

Description

Technical Field

[0001] This invention relates to a continuous casting protective slag, specifically a titanium-containing continuous casting protective slag. Background Technology

[0002] Mold flux is an important auxiliary material in continuous casting production, and its physicochemical properties directly affect the quality of the cast billets. Faced with fierce competition in the current steel market and the demands of social development, steel companies are researching and producing various high-strength, high-toughness, and easy-to-weld new varieties. Most mold fluxes used in continuous casting are slag systems with high fluorine content. However, fluorine in mold flux has a dual role: on the one hand, fluorides reduce the viscosity of the mold flux and participate in the formation of gun crystals to control heat transfer in the slag film; on the other hand, fluoride ions are acidic when they enter the secondary cooling water, which reduces the life of the casting machine and damages the environment and threatens human health when released into the atmosphere. The industry generally uses TiO2 to partially or completely replace fluorides.

[0003] For example, application number 201710796327.8 discloses a TiO2-containing high-alumina steel protective slag and its application. The slag, by mass percentage, is composed of the following oxides: CaO 30%–45%, Al2O3 16%–24.5%, SiO2 8%–16%, Na2O 8%–15%, Li2O 1%–5%, MgO 2%–6%, BaO 3%–7%, F- 6%–10%, TiO 2.7%–7%, and (CaO+BaO) / Al2O3 is 1.0–2.1. This protective slag has a low melting point and viscosity, and good crystallization properties. It is particularly suitable for the continuous casting of high-alumina steel with an Al mass percentage of 1.5–2.5%. When this protective slag is used, it can effectively reduce the degree of slag-steel reaction during continuous casting, making the crystallization and lubrication properties of the protective slag more stable, and greatly reducing the probability of quality defects such as pits, cracks, and inclusions on the surface of the billet.

[0004] However, the TiO2-containing high-alumina steel protective slag disclosed in this patent application has an excessively high TiO2 content, resulting in incomplete consumption of TiO2 in the molten state. 4+ At higher concentrations, it tends to form a TiO6 six-coordinate octahedral structure. At this point, titanium plays an excessive alkaline role in the system, resulting in an overall high alkalinity that affects lubrication and heat transfer performance. Summary of the Invention

[0005] The purpose of this invention is to provide a titanium-containing continuous casting protective slag to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A titanium-containing continuous casting mold flux has the following composition by mass percentage:

[0008] MgO: 4%-7%;

[0009] CaO: 35%-40%;

[0010] SiO2: 20%-28%;

[0011] TiO2: 4%-6%;

[0012] Al2O3: 7%-10%;

[0013] K2O: 3%-5%;

[0014] BaO: 4%-7%;

[0015] Pr6O 11 2%-4%;

[0016] C: 3%-4%;

[0017] The rest are unavoidable impurities.

[0018] As a preferred embodiment of the present invention, the ratio of CaO to SiO2 is 1:0.55-0.58, ensuring that the overall alkalinity of the continuous casting protective slag is within a suitable range.

[0019] As a preferred embodiment of the present invention, the ratio of TiO2 to SiO2 is 1:4-5, and the TiO2 content is... 4+ The ions generated are incorporated into the protective slag [Si₂O₇]. 6- The composite anionic groups provide free oxygen ions, which cause them to break and inhibit the precipitation and formation of gun crystals. When the ratio of TiO2 to SiO2 is too low, it will lead to excessive precipitation of gun crystals, which in turn will cause insufficient precipitation of feldspar and perovskite, thus reducing the heat preservation effect of the protective slag.

[0020] As a preferred embodiment of the present invention, the Pr6O 11 The total proportion of Al2O3+, SiO2+, and BaO is ≤44%, and Pr6O 11 An excessively high total amount of Al2O3, SiO2, and BaO can lead to an overly strong ability to precipitate crystals, which is detrimental to the structural stability and fluidity of the slag.

[0021] In this invention, due to the TiO2 in the protective slag at high temperature, Ti 4+ The ions will form a large number of TiO6 six-coordinate octahedral structures, exerting a basic effect. As a rare earth compound, it is inert at room temperature, but reacts with TiO2 at high temperatures.4+ A redox reaction occurs, and the reaction equation is:

[0022]

[0023] Make Pr6O 11 The Pr ions in the solution are reduced to Pr 3+ TiO2 contains Ti 4+ The ions are oxidized to TiO3, thus consuming excess Ti during the melting of the protective slag. 4+ Ions, inhibiting their alkaline effect.

[0024] As a preferred embodiment of the present invention, the Pr6O 11 The ratio of Pr6O to TiO2 is ≤6:11. 11 The molar ratio of Pr6O to TiO2 is 6:11, which is too high. 11 The ratio of TiO2 to Ti will cause Ti 4+ The large-scale consumption of ions results in a negative effect of excessively low viscosity and low crystal precipitation ability.

[0025] As a preferred embodiment of the present invention, the titanium-containing continuous casting protective slag has a melting point of 1200℃-1400℃ and a viscosity of 0.11-0.23 Pa·s at 1200℃-1400℃.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] This invention replaces fluorides in traditional protective slags with TiO2, achieving an environmentally friendly, functional protective slag without fluorides while ensuring reduced viscosity and controlled heat transfer. The rare earth compound Pr6O is also added. 11 In order to consume the excess Ti in the protective slag system 4+ Ions, to avoid causing excessively high overall alkalinity. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art.

[0029] The following embodiments of the present invention are used:

[0030] Magnesium ore, limestone, quartz sand, titanium ore, bauxite, potassium feldspar, and barite are all sourced from Jiangxi Liyou International Supply Chain Co., Ltd.

[0031] The rare earth ore was purchased from Baotou Steel (Group) Co., Ltd.

[0032] The graphite powder was purchased from Shandong Xinbaiyi Metal Materials Co., Ltd.

[0033] Example 1

[0034] In this embodiment, the titanium-containing continuous casting flux is composed of the following components by mass percentage: MgO: 5%; CaO: 38%; SiO2: 22%; TiO2: 5%; Al2O3: 10%; K2O: 4%; BaO: 6%; Pr6O 11 C: 2%; C: 3%; the remainder are unavoidable impurities, which are used as experimental protective residue 1.

[0035] Example 2

[0036] In this embodiment, the titanium-containing continuous casting flux is composed of the following components by mass percentage: MgO: 5%; CaO: 40%; SiO2: 20%; TiO2: 5%; Al2O3: 10%; K2O: 4%; BaO: 6%; Pr6O 11 C: 2%; C: 3%; the remainder are unavoidable impurities, which are used as experimental protective residue 2.

[0037] Example 3

[0038] In this embodiment, the titanium-containing continuous casting flux is composed of the following components by mass percentage: MgO: 5%; CaO: 38%; SiO2: 21%; TiO2: 6%; Al2O3: 10%; K2O: 4%; BaO: 6%; Pr6O 11 C: 2%; C: 3%; the remainder are unavoidable impurities, which are used as experimental protective residue 3.

[0039] Example 4

[0040] In this embodiment, the titanium-containing continuous casting flux is composed of the following components by mass percentage: MgO: 4%; CaO: 35%; SiO2: 27%; TiO2: 5%; Al2O3: 10%; K2O: 3%; BaO: 7%; Pr6O 11 :2%; C:3%; the remainder are unavoidable impurities, which are used as experimental protective residue 4.

[0041] Example 5

[0042] In this embodiment, the titanium-containing continuous casting flux is composed of the following components by mass percentage: MgO: 5%; CaO: 38%; SiO2: 22%; TiO2: 4%; Al2O3: 10%; K2O: 4%; BaO: 6%; Pr6O 11 :3%; C:3%; the remainder are unavoidable impurities, used as experimental protective residue 5.

[0043] Comparative Example 1

[0044] Using the same formulation and preparation process as in Example 1, the only difference is that TiO2 is replaced with an equal amount of CaF2 to obtain experimental protective slag 6.

[0045] Comparative Example 2

[0046] Comparative Example 2 uses the same formulation and preparation process as Example 1, the only difference being that it does not contain Pr6O. 11 By using the same mass of Na2O, experimental protective residue 7 was obtained.

[0047] During continuous casting production, experimental protective slag 1-7 was added to the crystallizer. After the protective slag melted, it spread evenly on the surface of the molten steel in the crystallizer. The viscosity and overall basicity were tested as shown in the table below:

[0048]

[0049] The data in the table above shows that when the ratio of CaO to SiO2 is too small, the overall basicity of the continuous casting flux increases significantly, while the Pr6O of TiO2 and SiO2... 11 When the total proportion of Al2O3, SiO2, and BaO is too high, it leads to a significant decrease in overall basicity and an increase in viscosity. However, as shown in Comparative Example 1, the performance of the continuous casting flux remains largely unchanged after replacing traditional fluorides with TiO2, and it even offers a slight advantage in viscosity. This allows for a more environmentally friendly formulation without compromising performance. However, as shown in Comparative Example 2, without using Pr6O... 11 Consume excess Ti under high temperature conditions 4+ The presence of ions will result in excessively high overall alkalinity in the continuous casting protective slag, which in turn leads to a significant decrease in heat transfer performance.

[0050] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A titanium-containing continuous casting protectional mold flux, characterized by: The mass percentage of its constituent components is: MgO: 4%-7%; CaO: 35%-40%; SiO2: 20%-28%; TiO2: 4%-6%; Al2O3: 7%-10%; K2O: 3%-5%; BaO: 4%-7%; Pr6O 11 : 2%-4% C： 3%-4%； The rest is inevitable impurities; The ratio of CaO to SiO2 is 1:0.55-0.58; The ratio of TiO2 to SiO2 is 1:4-5; The Pr6O 11 + Al2O3+ SiO2+ BaO is < 44%.

2. The titanium-containing continuous casting protective slag according to claim 1, characterized in that: The Pr6O 11 The ratio of Pr6O to TiO2 is ≤ 6:

11.

3. The titanium-containing continuous casting protective slag according to claim 1, characterized in that: The melting point of the titanium-containing continuous casting protective slag is 1200-1400℃, and the viscosity of the continuous casting protective slag at 1200-1400℃ is 0.11-0.23 Pa·s.

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