CN113070457A - Crystallizer casting powder for high-casting-speed continuous casting - Google Patents
Crystallizer casting powder for high-casting-speed continuous casting Download PDFInfo
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- CN113070457A CN113070457A CN202110320972.9A CN202110320972A CN113070457A CN 113070457 A CN113070457 A CN 113070457A CN 202110320972 A CN202110320972 A CN 202110320972A CN 113070457 A CN113070457 A CN 113070457A
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- casting
- crystallizer
- silicon
- covering slag
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/10—Supplying or treating molten metal
- B22D11/11—Treating the molten metal
- B22D11/111—Treating the molten metal by using protecting powders
Abstract
The invention discloses crystallizer casting powder for high-casting-speed continuous casting. Before the covering slag is added into the crystallizer, the covering slag comprises basic slag and a heating agent; the heating agent contains at least one of zero-valent silicon, zero-valent calcium, silicon-calcium alloy, silicon carbide, calcium carbide and silicon calcium carbide; the basic slag comprises CaO and SiO2、Al2O3、B2O3、MgO、Na2O、CaF2And C. The covering slag is added into a crystallizer and reacts to form binary alkalinity (CaO/SiO)2) A final mold flux of between 0.6 and 1.0. The casting powder has lower viscosity and melting temperature, higher melting speed, can form a stable liquid layer, well lubricate a casting blank, control heat transfer, absorb impurities in steel without generating the performance deterioration of the casting powder, and ensure the smooth operation of a continuous casting process.
Description
Technical Field
The invention belongs to the technical field of metallurgy, particularly relates to an auxiliary material used in a continuous casting process, and more particularly relates to crystallizer covering slag for high-casting-speed continuous casting.
Background
The continuous casting covering slag is a functional material for steel-making auxiliary covering on the surface of molten steel in the crystallizer of continuous casting machine, and has the functions of heat insulation, heat preservation, molten steel oxidation prevention, inclusion absorption, lubrication, heat transfer control and the like, and is the last process element for controlling the surface quality of casting blank in the steel-making process. At the present stage, because the steelmaking technology is continuously perfected, the steelmaking rhythm is accelerated, the steel output of the furnace is increased, and compared with the process capacity of steelmaking and steel rolling, the production capacity of the existing continuous casting machine is easy to become a restrictive link of the whole steelmaking plant. Efficient continuous casting becomes an important mark of continuous casting technology progress at the present stage, and the key is to improve the drawing speed on the premise of ensuring the quality of a casting blank. The mold flux for high-speed continuous casting must be reasonably solved as a critical factor.
The high-speed continuous casting refers to a continuous casting process with the drawing speed exceeding a certain specific value under certain process conditions, wherein the certain process conditions mainly comprise factors such as the section of a steel casting blank and the like. Whether the continuous casting machine can realize high-speed casting is related to a plurality of factors such as equipment state, operation process, molten steel quality, covering slag performance, automation level, production organization management and the like.
There is a large difference between high-speed continuous casting and constant-speed continuous casting. Under high speed continuous casting conditions:
(1) the heat flow of the crystallizer is increased, and the friction force borne by the crystallizer is increased;
(2) the flow speed of the molten steel at the water gap is accelerated, and the fluctuation of the molten steel surface in the crystallizer is intensified;
(3) the residence time of the molten steel in the crystallizer is short, and the thickness of an outlet billet shell is reduced;
(4) the slag consumption is reduced sharply, the stability and uniformity of the slag film are reduced, and poor lubrication and uneven heat transfer are caused.
The difference causes two major problems of bleed-out and casting blank defects of the high-speed continuous casting technology, and the improvement of the drawing speed is seriously influenced. In order to solve the two major problems of the high-speed continuous casting technology, the method needs to intensively study the covering slag for high-speed continuous casting besides improving the design of a submerged nozzle, automatically controlling the molten steel level and optimizing the crystallizer and the vibration mode thereof, and the like, and the covering slag has to meet the following requirements in order to meet the requirements of high-speed continuous casting: sufficient slag consumption is provided; maintaining sufficient liquid slag depth; maintaining stable operating characteristics; the heat transfer, both transverse and longitudinal, of the crystallizer can be well controlled.
Disclosure of Invention
Aiming at the problems that continuous casting protective slag reduces consumption with the increase of the pouring speed at present, so that the wall of a crystallizer and a solidified blank shell are not sufficiently lubricated and have uneven heat transfer, and casting blank surface defects, cohesive steel leakage and other accidents are easy to occur, the invention provides the crystallizer protective slag for high-casting-speed continuous casting, which optimizes components and is innovatively added with a heating agent with the addition of 0.5-1.5%. After the exothermic agent in the covering slag is burnt, the generated oxidation product and the original raw material of the covering slag form the final covering slag together, after the exothermic agent is added, the oxidation heat release is fast, the slag forming speed is accelerated, and the consumed liquid slag is quickly melted and supplemented; the spreading performance is good, the secondary oxidation of the molten steel can be prevented after the use, and harmful impurities on the surface of the molten steel can be adsorbed. The casting powder has the advantages of low viscosity, low melting temperature, high melting speed, physical and chemical properties, good lubricating capability, uniform slag film formation in the crystallizer, heat transfer control in the crystallizer, good inclusion absorption capability, high molten steel purity and capability of ensuring smooth continuous casting process.
In order to achieve the purpose, the technical scheme of the invention is as follows:
the invention relates to a crystallizer covering slag for high-casting speed continuous casting, which comprises basic slag and a heating agent before being added into a crystallizer; the heating agent contains at least one of zero-valent silicon, zero-valent calcium, silicon-calcium alloy, silicon carbide, calcium carbide and silicon calcium carbide; the basic slag comprises CaO and SiO2、Al2O3、B2O3、MgO、Na2O、CaF2、C。
Preferably, the mold flux for high-casting-speed continuous casting is characterized in that the heating agent in the mold flux is at least one of zero-valent silicon, zero-valent calcium and silicon-calcium alloy.
The crystallizer casting powder for high-casting-speed continuous casting is characterized in that the addition amount of a heating agent in the casting powder is 0.5-1.5%, and preferably 0.9-1.2%.
The invention relates to crystallizer covering slag for high-casting speed continuous casting, which is added into a crystallizer and then reacts to form final covering slag; the final casting powder comprises the following components in percentage by mass:
CaO 33％～36％；
SiO242％～47％；
Al2O31％～3％；
B2O31％～5％；
MgO 2％～3％；
Na2O 8％～10％；
CaF23％～6％；
C 2％～4.5％。
the invention relates to crystallizer casting powder for high-casting speed continuous casting, which is characterized in that the binary alkalinity (CaO/SiO) of the final casting powder2) Between 0.6 and 1.0.
Preferably, the invention relates to a high-speed chainCasting mold flux, the binary basicity (CaO/SiO) of the final flux2) Between 0.6 and 0.8.
The invention relates to crystallizer covering slag for high-casting speed continuous casting, which is added into a crystallizer, and then reacts and melts in 10-15s, preferably 10.5-12.5 s; the melting temperature is 950-.
The invention relates to a crystallizer covering slag for high-casting speed continuous casting, which is added into a crystallizer to react and melt to obtain molten covering slag; the viscosity of the molten mold flux at 1300 ℃ is 0.10-0.15 Pa.s.
Preferably, the mold flux for high-casting-speed continuous casting comprises the following components in percentage by mass
CaO 34.23％；
SiO243.37％；
Al2O31.6％；
B2O3 2.3％；
MgO 2.1％；
Na2O 8.2％；
CaF2 3.2％；
C4.1％；
0.9% of a heat generating agent; the heating agent is silicon-calcium alloy; in the silicon-calcium alloy, the mass percentage of Ca is 40%, and the mass percentage of Si is 60%.
CaO 35.75％；
SiO242.05％；
Al2O31.6％；
B2O3 2.3％；
MgO 2.1％；
Na2O 8.2％；
CaF2 3.2％；
C3.6％；
1.2% of a heat generating agent; the heating agent is a silicon-calcium alloy, wherein the mass percentage of Ca in the silicon-calcium alloy is 45%, and the mass percentage of Si in the silicon-calcium alloy is 55%. According to the invention, the scheme can improve the yield of the product under the condition that the pulling speed is 5.5 m/min.
The invention has the advantages of high heat value of the heating agent, quick oxidation and heat release, accelerated slagging speed and quicker melting and supplement of consumed liquid slag.
Compared with the prior art, the invention has the following advantages:
1) the crystallizer casting powder for high-casting-speed continuous casting has low viscosity, lower melting temperature and higher melting speed, can form a stable liquid layer, well lubricate a casting blank, and ensures the smooth running of continuous casting.
2) The crystallizer casting powder for high-drawing-speed continuous casting has good heat transfer control performance, can ensure that a primary blank shell with enough thickness is formed at high drawing speed, and prevents the leakage accident caused by the over-thin hydrostatic pressure of steel on the blank shell.
3) The crystallizer casting powder for high-casting-speed continuous casting has good stability and strong impurity absorption capacity, and can well prevent secondary oxidation of molten steel.
The specific implementation mode is as follows:
the invention is further illustrated by the following examples, which are intended to be illustrative only and are not intended to be in any way limiting.
The preparation process comprises the following steps:
1) taking the raw materials according to the distribution of a design group, and mechanically stirring the raw materials except C and the heating agent to uniformly mix the components;
2) heating and melting the mixed sample, and preserving heat for a period of time to remove volatile components and uniform slag components;
3) quenching the molten slag to obtain a glassy sample;
4) crushing a glassy sample, and adding required amount of carbonaceous material, a heating agent and a cellulose binder to prepare slurry;
5) and (3) feeding the obtained slurry into a spray particle drying tower for drying and granulating, wherein the water content of the product is required to be less than 0.5%, the granularity is in the range of 0.01-2 mm, and sealing and bagging the product for later use.
TABLE 1 chemical composition (wt%) of mold flux and its physicochemical properties of examples 1 to 3 and comparative examples 1 to 3
The heat generating agent used in example 1 was composed of calcium carbide, a silicon calcium alloy (Ca: 40 wt%, Si: 60 wt%), and a mixed powder of calcium carbide and silicon calcium alloy (Ca: 40 wt%, Si: 60 wt%) in a mass ratio of 1: 1.
The heat generating agent used in example 2 was composed of a silicon calcium alloy (Ca: 40 wt%, Si: 60 wt%).
The heat generating agent used in example 3 was composed of a silicon calcium alloy (Ca: 45 wt%, Si: 55 wt%).
As shown in Table 1, the melting temperatures of examples 1 to 3 were 1002 ℃, 981 ℃ and 970 ℃, respectively; the viscosities at 1300 ℃ are respectively 0.142 pas, 0.123 pas and 0.118 pas; the heat flux density is 3.9MW m respectively-2、4.1MW·m-2、4.6MW·m-2。
As can be seen from Table 1, the melting temperatures of comparative examples 1 to 3 were 1016 ℃, 996 ℃ and 983 ℃ respectively; viscosity at 1300 ℃ is 0.154 pas, 0.136 pas and 0.122 pas respectively; the heat flux density is 3.1MW m respectively-2、3.3MW·m-2、3.6MW·m-2。
Comparing examples 1 to 3 with comparative examples 1 to 3, it can be found that: the high-pulling-speed casting powder added with the heating agent has lower viscosity and melting temperature, higher melting speed and better lubricating capability than the high-pulling-speed casting powder without the heating agent, forms a uniform slag film in the crystallizer, controls heat transfer in the crystallizer, has good capability of absorbing impurities, improves the purity of molten steel, and ensures the smooth operation of a continuous casting process.
Under the condition that the drawing speed is 4.5m/min, the yield of the product of the example 1 is improved by 50 percent compared with that of the product of the comparative example 1.
Under the condition that the drawing speed is 5m/min, the yield of the product of the example 2 is improved by 75 percent compared with that of the product of the comparative example 2.
Under the condition that the drawing speed is 5.5m/min, the yield of the product of the example 3 is improved by 95 percent compared with that of the product of the comparative example 3.
Claims (10)
1. The mold flux for high casting speed continuous casting is characterized in that: before the covering slag is added into the crystallizer, the covering slag comprises basic slag and a heating agent; the heating agent contains at least one of zero-valent silicon, zero-valent calcium, silicon-calcium alloy, silicon carbide, calcium carbide and silicon calcium carbide; the basic slag comprises CaO and SiO2、Al2O3、B2O3、MgO、Na2O、CaF2、C。
2. The mold flux for high casting speed continuous casting according to claim 1, wherein: the heating agent in the covering slag is at least one selected from zero-valent silicon, zero-valent calcium and silicon-calcium alloy.
3. The mold flux for high casting speed continuous casting according to claim 1, wherein: the addition amount of the heating agent in the covering slag is 0.5-1.5%, and preferably 0.9-1.2%.
4. The high-pulling-speed crystallizer casting powder as defined in claim 3, wherein: the covering slag is added into a crystallizer and then reacts to form final covering slag; the final casting powder comprises the following components in percentage by mass:
CaO33％～36％；
SiO242％～47％；
Al2O31％～3％；
B2O31％～5％；
MgO 2％～3％；
Na2O 8％～10％；
CaF23％～6％；
C2％～4.5％。
5. the high pulling rate crystallizer protection of claim 4Slag, which is characterized in that: binary basicity (CaO/SiO) of the final mold flux2) Between 0.6 and 1.0.
6. The high-pulling-speed crystallizer casting powder as defined in claim 5, wherein: binary basicity (CaO/SiO) of the final mold flux2) Between 0.6 and 0.8.
7. The high-pulling-speed crystallizer casting powder as defined in claim 4, wherein: after the covering slag is added into a crystallizer, the covering slag reacts and is melted within 10-15 s; the melting temperature is 950-.
8. The high-pulling-speed crystallizer casting powder as defined in claim 4, wherein: adding the covering slag into a crystallizer, and reacting and melting to obtain molten covering slag; the viscosity of the molten mold flux at 1300 ℃ is 0.10-0.15 Pa.s.
9. The mold flux for a high casting speed crystallizer according to claim 1, wherein: the covering slag comprises the following components in percentage by mass
CaO 34.23％；
SiO243.37％；
Al2O31.6％；
B2O3 2.3％；
MgO 2.1％；
Na2O 8.2％；
CaF2 3.2％；
C4.1％；
0.9% of a heat generating agent; the heating agent is silicon-calcium alloy; in the silicon-calcium alloy, the mass percentage of Ca is 40%, and the mass percentage of Si is 60%.
10. The mold flux for a high casting speed crystallizer according to claim 1, wherein: the covering slag comprises the following components in percentage by mass
CaO 35.75％；
SiO242.05％；
Al2O31.6％；
B2O3 2.3％；
MgO 2.1％；
Na2O 8.2％；
CaF2 3.2％；
C3.6％；
1.2% of a heat generating agent; the heating agent is a silicon-calcium alloy, wherein the mass percentage of Ca in the silicon-calcium alloy is 45%, and the mass percentage of Si in the silicon-calcium alloy is 55%.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114045374A (en) * | 2021-11-19 | 2022-02-15 | 西峡龙成冶金材料有限公司 | Special covering slag for nodular cast iron and preparation method and application thereof |
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| CN110538973A (en) * | 2018-05-29 | 2019-12-06 | 宝山钢铁股份有限公司 | light-weight fluorine-free environment-friendly continuous casting covering slag special for enamel steel |
| CN110548841A (en) * | 2018-06-04 | 2019-12-10 | 上海梅山钢铁股份有限公司 | Low-sodium low-lithium continuous casting crystallizer casting powder for low-carbon steel |
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2021
- 2021-03-25 CN CN202110320972.9A patent/CN113070457B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02220749A (en) * | 1989-02-22 | 1990-09-03 | Nisshin Steel Co Ltd | Initial stage casting method in continuous casting of stainless steel |
| JPH0852550A (en) * | 1994-08-11 | 1996-02-27 | Sumitomo Metal Ind Ltd | Mold powder for continuous casting of steel |
| CN1911559A (en) * | 2006-08-25 | 2007-02-14 | 重庆大学 | Protective slag for ultralow carbon steel continuous casting |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114045374A (en) * | 2021-11-19 | 2022-02-15 | 西峡龙成冶金材料有限公司 | Special covering slag for nodular cast iron and preparation method and application thereof |
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