Molten steel clean pouring method for replacing ladle filler sand

Abstract

The invention belongs to the field of ferrous metallurgy, and particularly relates to a molten steel clean pouring method for replacing ladle filler sand, which mainly comprises the flow of plugging alloy pre-packaging, plugging alloy filling, molten steel containing in a ladle, secondary refining and hot delivery, and ladle casting. According to the method, operation is easy, clean casting of the molten steel is easy to achieve, use of stuffing sand in the traditional tapping process is completely avoided, and large-scale application and popularization of the technology are expected to be achieved.

Description

Technical Field

[0001] The invention belongs to the field of iron and steel metallurgy, and in particular relates to a method for cleanly pouring molten steel that replaces ladle drainage sand. Background Art

[0002] In the iron and steel metallurgical process, the degree of cleanliness of the molten steel has a decisive influence on the final quality of the steel. Currently, during the smelting and pouring process, drainage sand is commonly used at the bottom of the ladle to seal the bottom water inlet, and steel tapping and molten steel pouring are achieved by opening and closing the slide. However, the use of drainage sand not only causes certain environmental pollution, but also due to its small particle size and short casting process, it is difficult to completely remove this drainage sand, which ultimately remains in the molten steel, resulting in a significant increase in the oxygen content and the number of inclusions in the molten steel. Even if the molten steel has a high degree of cleanliness during the initial smelting process, the presence of drainage sand may still cause a certain degree of secondary contamination to the molten steel, thereby affecting the final quality of the steel.

[0003] In order to eliminate the impact of drainage sand on the clean casting of molten steel, relevant technical personnel in this field have proposed a variety of alternative solutions, such as manual sand collection with an external sand collection box, high-pressure argon blowing, and the use of low-melting-point alloys in the sealing layer. However, these methods have certain limitations in practical applications. It is usually impossible to completely avoid the use of drainage sand, and it is difficult to fundamentally achieve clean casting of molten steel. In addition, the operating procedures of the above-mentioned technical methods are relatively complicated, which imposes certain restrictions on the production rhythm and efficiency of continuous casting and mold casting sites, and is not conducive to long-term and large-scale promotion. At the same time, some technologies may also bring certain safety hazards. Therefore, it is particularly important to develop a method for clean casting of molten steel that is simple to operate, efficient, and can replace ladle drainage sand. Summary of the Invention

[0004] To address the problems of drainage sand in existing technologies causing secondary contamination of the molten steel during the pouring process, affecting steel quality, and resulting in complex and inefficient operations, the present invention provides a clean steel pouring method that replaces ladle drainage sand. By replacing traditional drainage sand with a prefabricated metal plugging assembly and combining the principles of self-propagating oxidation reaction and heat conduction, efficient sealing of the molten steel and automatic pouring are achieved. This method not only avoids the use of drainage sand but also significantly reduces the inclusion and oxygen content in the molten steel, while simplifying the operational process and making it suitable for large-scale industrial applications.

[0005] The technical solution of the present invention is: A method for clean molten steel pouring that replaces ladle drainage sand, the specific implementation steps of which are as follows: 1) Pre-packaging of plugging alloy: Fill the metal plugging material into a prefabricated thin metal barrel and seal it with flammable materials to prevent the plugging material from flowing out prematurely or undergoing chemical reactions during the ladle circulation process; 2) Sealing alloy filling: Before the ladle is filled with molten steel, the packaged metal sealing component is pushed into the nozzle from the bottom of the ladle and the slide is closed to ensure that the molten steel will not leak during the subsequent flow process; 3) Ladle filling with molten steel, secondary refining and hot delivery: After the ladle is filled with molten steel, the metal sealing component gradually heats up through heat conduction, changing from the initial "cold state" to a "hot state" with a certain temperature, thereby enhancing the sealing effect and preventing excessive infiltration of molten steel.

[0006] 4) Ladle pouring: When the ladle slides open, the metal seal is exposed to the air. The active metal in the core rapidly comes into contact with oxygen, causing a self-propagating oxidation reaction and releasing a large amount of heat, further heating and melting the surrounding metal. As the reaction continues, the metal seal gradually flows out of the ladle's bottom outlet. Eventually, the molten steel, under static pressure, breaks through the barrier, allowing pouring to proceed smoothly.

[0007] Furthermore, in the aforementioned clean steel pouring method that replaces ladle drain sand, the metal plugging material is selected from one or more metals such as Fe, Al, Mg, Mn, Ni, Ti, Cr, Mo, V, Cu, and rare earth elements, and their alloys. The melting point of the selected material must be maintained above 500°C. The particle size of the metal plugging material is controlled to be less than 3mm to ensure rapid melting and uniform flow during the reaction.

[0008] Furthermore, in the above-mentioned method for clean molten steel pouring that replaces ladle drainage sand, the material of the thin metal barrel is inert metals such as Fe, Al, Si, Cu and their alloys, its external dimensions match the internal dimensions of the ladle bottom water inlet, and the wall thickness does not exceed 0.5mm.

[0009] Furthermore, in the aforementioned clean steel pouring method, which replaces ladle drain sand, the top of the thin metal barrel is filled with metallic Fe powder, with a particle size not exceeding 1 mm and a filling thickness of at least 30 mm. This top Fe powder layer acts as a physical barrier, effectively preventing the penetration of molten steel and preventing the plugging material from prematurely dissolving into the molten steel during the initial heat conduction process.

[0010] Furthermore, in the aforementioned clean steel pouring method that replaces ladle drain sand, the filling structure of the metal plugging material can be adjusted according to specific needs, including single metal filling, multi-metal mixed filling, or multi-metal layered filling. During layered filling, different metals are gradually filled from the core outward according to the chemical properties of the metals to optimize reaction rate and melting sequence.

[0011] Furthermore, in the aforementioned clean steel pouring method that replaces ladle drain sand, when the metal plugging assembly exhibits a slow reaction rate during ladle pouring, supplemental oxygenation can be used to accelerate the self-propagating reaction rate and the melting process. This supplemental oxygenation can be achieved by introducing oxygen-enriched gas into the ladle bottom nozzle area, with the flow rate and concentration of the oxygen-enriched gas adjusted based on the actual reaction conditions.

[0012] Furthermore, in the above-mentioned method for clean molten steel pouring that replaces ladle drainage sand, the packaging steps of the metal sealing component are as follows: first, Fe powder with a particle size of 0.05 mm is filled into the top of the thin metal barrel to form a top Fe powder layer with a thickness of 30-50 mm, and then the remaining metal material is filled with a particle size controlled between 0.1-3 mm, and finally the thin metal barrel is sealed with a flammable material.

[0013] Furthermore, in the above-mentioned method for clean molten steel pouring that replaces ladle drainage sand, during the ladle pouring process, the active metal in the core of the metal sealing component is selected from one or more of Mg, Al or Ti.

[0014] Advantages and beneficial effects of the present invention: (1) Traditional drainage sand particles are fine and difficult to completely remove, easily accumulating in the molten steel and forming inclusions. Metal plugging components, on the other hand, can completely melt under high temperature conditions and participate in the microalloying process of the molten steel, generating very little oxide, and causing almost negligible secondary contamination of the molten steel. Furthermore, the metal plugging components can reach the ideal reaction temperature through heat conduction during the ladle circulation process, eliminating the need for additional heating and simplifying the process.

[0015] (2) The metal filling materials used are all common and commonly used metal and alloy raw materials in current steel mills, which are easy to obtain and use. At the same time, the metal thin barrels used in the present invention are also easy to process and obtain on site, and can be prepared and stored in large quantities before the ladle is used, greatly improving the convenience and practicality of the process. Traditional drainage sand steelmaking technology currently uses the upper part of the ladle to fill the ladle, with a large amount of filling and needs to be spread to the bottom of the ladle to form a bun shape, resulting in a large amount of raw material waste. Compared with this, the present invention not only uses less sealing raw materials and has a higher utilization rate, but also can ensure the same sealing effect as drainage sand.

[0016] (3) The metals and alloys used in the present invention do not pollute the molten steel after entering it, and they also play a beneficial role in secondary microalloying of the molten steel. Even if a small amount of oxides is generated when the plugging alloy contacts and reacts with oxygen, the amount generated is extremely small. Compared with the original drainage sand, the secondary pollution problem of the molten steel is negligible. In addition, the present invention does not require secondary heating of the plugging alloy. Only heat conduction during the ladle circulation process can bring the plugging alloy to above the ideal reaction temperature. After the slide plate is opened and contacts oxygen, a chemical reaction is initiated and a large amount of heat energy is generated, which promotes the melting of the surrounding alloy.

[0017] (4) In the plugging alloy filling structure described in the present invention, the ultrafine iron powder filling structure with a top thickness of not less than 30 mm can effectively prevent the dissolution of the top alloy and the penetration of the molten steel after the surface of the plugging alloy contacts the molten steel. This ensures that the thickness of the cold steel layer on the top of the plugging alloy will not exceed the conditions required for the molten steel to break through the plugging layer under static pressure and achieve automatic steel tapping. At the same time, the top iron powder can also serve as a physical barrier between the liquid steel and the lower metal or alloy, and can also ensure that the molten steel will not come into contact with the molten steel during the early smelting and hot delivery process, resulting in problems such as premature dissolution into the molten steel. This effectively ensures the self-opening effect and self-opening rate of the ladle itself, and effectively ensures the large-scale application and promotion of the technology described in the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic structural diagram of an embodiment of the present invention, showing the layered structure of a thin metal barrel and its internal filling material, including a top Fe powder layer and a core active metal filling area.

[0019] Figure 2 This is a schematic diagram of the reaction state of the metal sealing assembly during the ladle pouring process in an embodiment of the present invention, showing the oxidation reaction process of the sealing assembly exposed to the air after the slide plate is opened and the state of the molten steel breaking through the barrier.

[0020] In the figure, 1-metal sealing assembly; 101-metal thin barrel; 102-top Fe powder layer; 103-core active metal filling area; 2-ladle; 3-upper water inlet; 4-slide plate; 5-molten steel. DETAILED DESCRIPTION

[0021] like Figure 1-2 As shown, the present invention provides a method for clean pouring of molten steel that replaces ladle drainage sand. The core of the method is to replace traditional drainage sand with a metal sealing component 1 to achieve efficient sealing and automatic pouring of molten steel.

[0022] In the embodiment, the overall structure of the metal sealing assembly 1 includes a thin metal barrel 101, a top Fe powder layer 102, and a core active metal filling area 103. The thin metal barrel is the outer shell of the entire sealing assembly 101, and its material is selected from inert metals such as Fe or Al and their alloys, and the wall thickness does not exceed 0.5mm. The outer dimensions of the thin metal barrel 101 match the internal dimensions of the water inlet at the bottom of the ladle to ensure that it can be pushed tightly into the water inlet and remain stable. The top Fe powder layer 102 is located in the upper part of the thin metal barrel 101, with a thickness of 30-50mm and a particle size controlled below 0.05mm. The main function of the top Fe powder layer 102 is to act as a physical barrier to prevent the penetration of molten steel, and at the same time prevent the core active metal from dissolving into the molten steel prematurely during the early heat conduction process. The core active metal filling area 103 is located at the lower portion of the thin metal barrel 101 and is filled with a metal material with a particle size of 0.1-3 mm. This metal material is selected from one or more metals such as Fe, Al, Mg, Mn, Ni, Ti, Cr, Mo, V, Cu, and rare earth elements, and their alloys, and must maintain a melting point above 500°C. The filling structure of the core active metal filling area 103 can be designed to be filled with a single metal, a mixed metal filling, or a layered filling of multiple metals according to actual needs. During layered filling, different metals are gradually added from the core toward the outer diameter based on the chemical properties of the metals to optimize the reaction rate and melting sequence.

[0023] In actual operation, the following steps are included: First, the sealing alloy pre-packaging step is performed. Fe powder with a particle size of 0.05 mm is filled into the top of the prefabricated thin metal barrel 101 to form a top Fe powder layer 102. The filling thickness is controlled between 30-50 mm. The remaining metal material is then filled into the core active metal filling area 103 according to the design requirements. After filling, the thin metal barrel 101 is sealed with a flammable material. The sealing material must be selected to ensure that it can burn quickly under high temperature conditions without leaving residue, thereby preventing contamination of the molten steel.

[0024] After the packaging is completed, the metal sealing assembly 1 is pushed into the water inlet 3 at the bottom of the ladle 2 and fixed in place by a mechanical device. Then the slide 4 is closed to ensure that the metal sealing assembly 1 remains stable during the filling and hot delivery of the molten steel 5.

[0025] After the ladle 2 is filled with molten steel 5, the metal sealing assembly 1 gradually heats up through heat conduction. The top Fe powder layer 102 plays a key role in the heat conduction process. Its higher density and smaller particle size enable it to effectively block the penetration of molten steel. At the same time, its lower melting point ensures that it will not melt prematurely in the early stages of heat conduction. As the temperature rises, the metal material in the core active metal filling area 103 gradually reaches the temperature required for the reaction. During the hot delivery process of the ladle 2, the metal sealing assembly 1 changes from an initial cold state to a hot state with a certain temperature, thereby enhancing the sealing effect and preventing excessive infiltration of the molten steel 5.

[0026] The ladle 2 starts pouring. When the slide 4 is opened, the metal sealing assembly 1 is exposed to the air. The active metals such as Mg, Al or Ti in the active metal filling area 103 of the core quickly come into contact with oxygen to undergo a self-propagating oxidation reaction and release a large amount of heat. The heat in the oxidation reaction area further increases the temperature of the surrounding metal, causing it to melt quickly and gradually flow out of the water outlet. In this process, the role of the top Fe powder layer 102 is once again apparent. Its lower melting point and higher density ensure that a certain structural stability can be maintained in the early stage of the reaction, thereby preventing the molten steel 5 from breaking through the barrier prematurely. As the reaction continues, the metal sealing assembly 1 gradually flows out from the bottom water outlet of the ladle 2, and finally the molten steel 5 breaks through the barrier under the action of static pressure to achieve smooth pouring.

[0027] If the reaction rate of the metal plugging assembly 1 is slow during the ladle 2 pouring process, auxiliary oxygenation can be used to accelerate the self-propagating reaction rate and melting process. This auxiliary oxygenation is achieved by introducing oxygen-enriched gas into the ladle bottom water inlet area. The flow rate and concentration of the oxygen-enriched gas are adjusted according to the actual reaction conditions. This method ensures that the metal plugging assembly 1 completes the oxidation reaction and melting process in a short time, thereby improving pouring efficiency.

[0028] The specific implementation methods of the present invention are further described in detail below with reference to examples.

[0029] Example 1

[0030] This embodiment conducts experiments on a 120-ton ladle used in a low-carbon steel slab continuous casting process at a certain steel plant.

[0031] First, before the experiment, metal iron powder with a particle size of 0.05mm was placed on the top of the prefabricated metal iron thin barrel with a filling thickness of 40mm. The remaining part was filled with metal magnesium in the center (filling diameter was 25mm) and metal iron powder in the rest of the barrel. The filling alloy particle size was 0.1mm.

[0032] After filling is completed, the thin metal barrel is sealed with flammable materials to prevent the alloy from flowing out prematurely.

[0033] Then, before the ladle is filled with molten steel, the pre-packaged sealing alloy is pushed from the bottom of the ladle into the water inlet, and then the slide is closed.

[0034] Subsequently, during the ladle's filling, secondary refining, and hot delivery processes, the sealing alloy effectively seals the molten steel and prevents excessive infiltration. Simultaneously, heat conduction between the metals transforms the sealing alloy from its original "cold" state to a "hot" state at a specific temperature.

[0035] When the ladle opens the slide to prepare for pouring, the blocking alloy will be directly exposed to the air environment, and the active metal in the core will begin to undergo a self-propagating oxidation reaction and release a large amount of heat after contact with oxygen, driving the surrounding metal to further heat up and melt. As the reaction and melting process continue, the blocking alloy will gradually flow out from the water outlet at the bottom of the ladle. Finally, the molten steel inside the ladle will break through the barrier under the action of the static pressure of the molten steel, thereby realizing the smooth pouring of the ladle.

[0036] Tests have shown that compared with conventional sand-draining steelmaking technology, the overall inclusion count of the ingot in this embodiment was reduced by 52% and the oxygen content by 56%. In the initial stages of ladle pouring, the inclusion count and oxygen content were reduced by 68% and 74%, respectively.

[0037] Example 2

[0038] This embodiment conducts experiments on a 40-ton ladle used in a special steel mold casting process at a steel plant.

[0039] First, before the experiment, metal iron powder with a particle size of 0.05mm was placed on the top of the prefabricated metal iron thin barrel with a filling thickness of 35mm. The remaining part was filled with metal titanium in the center (filling diameter was 20mm) and metal Al powder in the rest of the barrel. The filling alloy particle size was 0.1mm.

[0040] After filling is completed, the thin metal barrel is sealed with flammable materials to prevent the alloy from flowing out prematurely.

[0041] Then, before the ladle is filled with molten steel, the pre-packaged sealing alloy is pushed from the bottom of the ladle into the water inlet, and then the slide is closed.

[0042] Subsequently, during the ladle's filling, secondary refining, and hot delivery processes, the sealing alloy effectively seals the molten steel and prevents excessive infiltration. Simultaneously, heat conduction between the metals transforms the sealing alloy from its original "cold" state to a "hot" state at a specific temperature.

[0043] When the ladle opens the slide to prepare for pouring, the blocking alloy will be directly exposed to the air environment, and the active metal in the core will begin to undergo a self-propagating oxidation reaction and release a large amount of heat after contact with oxygen, driving the surrounding metal to further heat up and melt. As the reaction and melting process continue, the blocking alloy will gradually flow out from the water outlet at the bottom of the ladle. Finally, the molten steel inside the ladle will break through the barrier under the action of the static pressure of the molten steel, thereby realizing the smooth pouring of the ladle.

[0044] Testing has shown that compared with conventional sand-draining steelmaking technology, the overall inclusion count of the ingot in this embodiment was reduced by 55% and the oxygen content by 64%. In the initial stages of ladle pouring, the inclusion count and oxygen content were reduced by 67% and 75%, respectively.

[0045] Example 3

[0046] This embodiment conducts experiments on a 120-ton ladle used in a low-carbon steel slab continuous casting process at a certain steel plant.

[0047] First, before the experiment, metal iron powder with a particle size of 0.05 mm was placed in a prefabricated metal iron thin barrel. After the filling was completed, the metal thin barrel was sealed with flammable materials to prevent the alloy from flowing out prematurely.

[0048] Then, before the ladle is filled with molten steel, the pre-packaged sealing alloy is pushed from the bottom of the ladle into the water inlet, and then the slide is closed.

[0049] Subsequently, during the ladle's filling, secondary refining, and hot delivery processes, the sealing alloy effectively seals the molten steel and prevents excessive infiltration. Simultaneously, heat conduction between the metals transforms the sealing alloy from its original "cold" state to a "hot" state at a specific temperature.

[0050] When the ladle opens the slide to prepare for pouring, the blocking alloy will be directly exposed to the air environment. Through the auxiliary oxygen enrichment, the blocking alloy will melt quickly and drive the surrounding metal to further heat up and melt. As the reaction and melting process continue, the blocking alloy will gradually flow out from the water outlet at the bottom of the ladle. Finally, the molten steel inside the ladle will break through the barrier under the action of the static pressure of the molten steel, thereby realizing the smooth pouring of the ladle.

[0051] Testing has shown that compared with conventional sand-draining steelmaking technology, the overall inclusion count of the ingot in this embodiment was reduced by 46% and the oxygen content by 40%. In particular, the inclusion count and oxygen content during the initial ladle pouring phase were reduced by 65% ​​and 59%, respectively.

Claims

1. A method for purifying molten steel by replacing ladle drainage sand, characterized in that: The specific steps include: 1) Fill the metal sealing material into the thin metal barrel and seal it with flammable materials; 2) Before the ladle is filled with molten steel, push the encapsulated metal sealing component from the bottom of the ladle into the water inlet and close the slide; 3) After the ladle is filled with molten steel, the metal plugging component gradually heats up through heat conduction, changing from the initial "cold state" to a "hot state" with a certain temperature, thereby enhancing the plugging effect and preventing excessive infiltration of molten steel; 4) Open the slide plate, and the metal sealing component is exposed to the air. The active metal in the core comes into contact with oxygen, causing a self-propagating oxidation reaction and releasing heat, which drives the surrounding metal to melt and gradually flow out of the water outlet. Under the action of static pressure, the molten steel breaks through the barrier to start pouring.

2. The method for purifying molten steel by replacing ladle drainage sand according to claim 1, characterized in that: The metal sealing material is selected from one or more of Fe, Al, Mg, Mn, Ni, Ti, Cr, Mo, V, Cu and rare earth elements. The melting point of the selected material is not lower than 500°C and the particle size does not exceed 3mm.

3. The method for purifying molten steel by replacing ladle drainage sand according to claim 1, characterized in that: The metal thin barrel is made of Fe, Al, Si or Cu and its alloys, with a wall thickness not exceeding 0.5 mm and an external dimension matching the internal dimension of the water inlet at the bottom of the ladle.

4. The method for purifying molten steel by replacing ladle drainage sand according to claim 1, characterized in that: The top of the thin metal barrel is filled with a Fe powder layer with a thickness of not less than 30 mm and a particle size of the Fe powder not exceeding 1 mm.

5. The method for purifying molten steel by replacing ladle drainage sand according to claim 1, characterized in that: The filling structure of the metal plugging material is single metal filling, multi-metal mixed filling or multi-metal layered filling. During layered filling, different metals are gradually filled from the core to the outer diameter according to the chemical properties of the metal.

6. The method for purifying molten steel by replacing ladle drainage sand according to claim 1, characterized in that: When the reaction rate of the metal plugging component is low, oxygen-rich gas is introduced into the water inlet area at the bottom of the ladle to accelerate the self-propagating reaction rate and the melting process.

7. The method for clean molten steel pouring replacing ladle drainage sand according to claim 1, characterized in that: The packaging steps of the metal sealing component are as follows: first fill the top of the metal thin barrel with Fe powder with a particle size of 0.05mm to form a top Fe powder layer with a thickness of 30-50mm, then fill the remaining metal material with a particle size controlled between 0.1-3mm, and finally seal the metal thin barrel with flammable materials.

8. The method for clean molten steel pouring replacing ladle drainage sand according to claim 1, characterized in that: During the ladle pouring process, the active metal in the core of the metal plugging component is selected from one or more of Mg, Al or Ti.

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