Filling material for inhibiting oxidation of integral nozzle of continuous casting tundish and construction and installation method

Abstract

The invention provides a filler for inhibiting oxidation of an integral nozzle of a continuous casting tundish and a construction and installation method, the filler comprises chrome corundum fire clay and water glass, and the filler is obtained by mixing the chrome corundum fire clay and the water glass according to the weight ratio of (8-12): 1 until the mixture is held by a hand and does not flow. The construction and installation method comprises the steps that after the integral water gap and the separation ring are installed in place and centered, the filler is adopted to fill and plug a gap in the connecting position of the tundish body and the integral water gap. A small amount of gap filler between the nozzle below the tundish bottom and the hole wall is subjected to formula improvement, and the chrome corundum fire clay and the water glass are proportionally and uniformly mixed until the mixture is held by a hand and does not flow, so that the gap between the nozzle below the tundish bottom and the hole wall is compactly filled, and the gap between the nozzle below the tundish bottom and the hole wall is protected while a protection effect is achieved. The adverse effect of water in the filler on an enamel layer at the root of the whole nozzle is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of continuous casting in steel mills, and specifically refers to a filler for suppressing oxidation of the tundish monoblock nozzle and a construction and installation method therefor. Background Art

[0002] For the existing tundish monoblock nozzle in steel enterprises, especially in the construction and installation of the tundish during the repair of the slab caster, it is mostly inserted from below the tundish bottom into the tundish bottom through the nozzle hole, and then the monoblock nozzle is fixed and clamped through the bottom brick of the tundish or the split ring. The gap is filled with clay fireclay, and then the tundish spraying material is applied and leveled in the nozzle area at the bottom of the tundish cavity. In this structure, there are still a small amount of gaps between the nozzle below the tundish bottom and the hole wall. If not filled and protected, the nozzle is likely to break during hoisting and baking, and there is also a risk of molten steel leakage, which will have a significant impact on production.

[0003] Most of the existing solutions are to mix chromic corundum fireclay and water in a certain ratio and then stuff it into the gap between the nozzle below the tundish bottom and the hole wall for filling and protection, as Figure 1 shown. Although this method can play a role in filling and protection, the moisture in the filler is likely to damage the enamel layer at the root of the monoblock nozzle, causing oxidation at the root of the nozzle. When exposed to air during production, the refractory material forms oxidation points that gradually expand, resulting in strength failure and causing unplanned caster stops such as shedding and steel penetration accidents. For the problem of steel leakage in the aluminum-carbon monoblock nozzle, the Chinese patent document with the application number CN201120154484.7 discloses a tundish monoblock nozzle for continuous casting, which consists of a nozzle body, refractory seat bricks around the body, and an interlayer filler layer. By limiting the expansion rate of the material of the low-deformation refractory section in the gap to be the same as or close to that of the refractory seat brick, the problem of the gap between the nozzle and the seat brick expanding can be effectively solved, avoiding steel leakage in the aluminum-carbon monoblock nozzle, thereby increasing the safety factor of the tundish. However, this solution does not optimize the interlayer filler layer and does not solve the problem of the oxidation points of the refractory material gradually expanding due to the filler in the gap between the nozzle and the hole wall. Summary of the Invention

[0004] To overcome the deficiencies of the above technologies, the purpose of the present invention is to provide a filler for suppressing oxidation of the tundish monoblock nozzle and a construction and installation method therefor, to solve the problem that the moisture in the filler in the gap between the nozzle below the tundish bottom and the hole wall of the existing tundish monoblock nozzle in steel mills damages the enamel layer at the root of the monoblock nozzle, causing oxidation at the root of the nozzle. When exposed to air during production, the refractory material forms oxidation points that gradually expand, resulting in strength failure and causing unplanned caster stops such as shedding and steel penetration accidents.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A filler for inhibiting oxidation of the monolithic nozzle in continuous casting tundish, characterized in that: it includes chrome corundum fire clay and water glass (Na2O.nSiO2), and is used to fill the gap at the connection between the tundish body and the monolithic nozzle. Among them, the refractoriness of the chrome corundum fire clay is ≥1780 °C, the mass percentage content of Al2O3 is ≥70.00%, and the mass percentage content of Cr2O3 is ≥10.00%. The modulus of water glass n = 2.0 - 3.5, and it can be fully mixed with chrome corundum fire clay at room temperature, and after curing, it has both high bonding strength and refractoriness.

[0007] As a preferred solution, the weight ratio of the chrome corundum fire clay to the water glass is 8 - 12:1.

[0008] Further, the weight ratio of the chrome corundum fire clay to the water glass is 10:1.

[0009] The preparation method of the above-mentioned filler is characterized in that: it includes mixing the chrome corundum fire clay and the water glass according to a set weight ratio until it does not flow when held by hand.

[0010] As a preferred solution, the mixing time in the mixing process is 3 - 25 min.

[0011] Further, the weight ratio of the chrome corundum fire clay to the water glass is 10:1, and the mixing time is 5 - 10 min.

[0012] The present invention also provides a construction and installation method for inhibiting oxidation of the monolithic nozzle in continuous casting tundish, characterized in that: it includes filling and blocking the gap at the connection between the tundish body and the monolithic nozzle with a filler after the monolithic nozzle and the separating ring are installed in place and centered; the filler is the above-mentioned filler or the filler prepared by the above-mentioned preparation method.

[0013] Further, the gap is the gap between the wall of the nozzle installation hole on the tundish body for installing the monolithic nozzle and the outer wall of the monolithic nozzle.

[0014] As a preferred solution, the use method of the filler includes: mixing the chrome corundum fire clay and the water glass according to a set weight ratio until it does not flow when held by hand, and then stuffing it into the gap between the monolithic nozzle and the nozzle installation hole on the tundish body, so as to play a role in fixing the monolithic nozzle and preventing oxidation.

[0015] As a preferred solution, the construction and installation method includes the following steps: 1) Installing the monolithic nozzle; 2) Installing the separating ring; 3) Filling and blocking the gap at the connection between the tundish body and the monolithic nozzle with a filler.

[0016] Further, the construction and installation method specifically includes:

[0017] 1) Installation of the integral tundish nozzle: Handling of the integral tundish nozzle and alignment of the nozzle position

[0018] Carry the integral tundish nozzle to the lower part of the tundish to be constructed and installed, then extend the top of the nozzle into the tundish through the nozzle installation hole at the bottom of the tundish body and align it to ensure that the integral tundish nozzle is vertically downward and in alignment;

[0019] 2) Installation of the split ring

[0020] After the root of the nozzle is fed into the nozzle installation hole, clamp the root of the nozzle at the bottom inside the tundish with a split ring coated with chrome corundum fire clay to fix and limit the integral tundish nozzle, and tap the split ring to adjust the alignment position;

[0021] 3) Sealing of the nozzle installation hole at the bottom of the tundish

[0022] After the split ring is set, use the filling material to fill and seal the gap between the integral tundish nozzle and the hole wall of the nozzle installation hole at the bottom of the tundish body.

[0023] Furthermore, after the construction and installation are completed, let the tundish stand still for at least 24 hours. After 24 hours, put it into production after baking in the tundish. The baking temperature is 1300 - 1340 °C, and the baking time is 2 - 3 hours.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] The present invention provides a filling material and a construction and installation method for suppressing the oxidation of the integral tundish nozzle in continuous casting. The formula of the filling material for the small gap between the nozzle under the bottom of the tundish and the hole wall is improved. Chrome corundum fire clay and water glass (Na2O.nSiO2) are proportioned and mixed evenly until it can be held by hand without flowing. Then, the gap between the nozzle under the bottom of the tundish and the hole wall is filled tightly, which not only plays a protective role but also avoids the adverse effects of the moisture in the filling material on the enamel layer at the root of the integral tundish nozzle. Description of the drawings

[0026] Figure 1 It is a physical diagram of sealing the gap between the integral tundish nozzle and the hole at the bottom of the tundish;

[0027] Figure 2 It is a schematic diagram of installing the integral tundish nozzle;

[0028] In the figure: 1. Nozzle installation hole; 2. Tundish body; 3. Integral tundish nozzle; 4. Split ring; 5. Gap. Specific embodiments

[0029] In order to better explain the present invention, the main content of the present invention is further clarified below in conjunction with specific embodiments, but the content of the present invention is not limited to the following embodiments only.

[0030] Example 1

[0031] A filler for inhibiting oxidation of the tundish monoblock nozzle, used to fill the gap at the connection between the tundish body and the monoblock nozzle, includes chrome corundum fire clay and water glass, with a weight ratio of 8:1. Among them, the refractoriness of the chrome corundum fire clay is ≥1780 °C, the mass percentage content of Al2O3 is 75%, and the mass percentage content of Cr2O3 is 13%. The modulus n of the water glass is 2.0 - 3.5, and it can be fully mixed with the chrome corundum fire clay at room temperature, and after curing, it has both high bonding strength and fire resistance.

[0032] The preparation method of the filler in this example includes mixing chrome corundum fire clay and water glass (Na2O·nSiO2) according to a ratio of 8:1, and mixing evenly at 25 °C until it does not flow when held by hand, that is, no liquid drips when held in the palm at 25 °C for 10 seconds, and the mixing time is 20 min.

[0033] Example 2

[0034] The difference between this example and Example 1 is that: the weight ratio of chrome corundum fire clay to water glass is 9:1; the mixing time is 15 min.

[0035] Example 3

[0036] The difference between this example and Example 1 is that: the weight ratio of chrome corundum fire clay to water glass is 10:1; the mixing time is 7 min.

[0037] Example 4

[0038] The difference between this example and Example 1 is that: the weight ratio of chrome corundum fire clay to water glass is 11:1; the mixing time is 5 min.

[0039] Example 5

[0040] The difference between this example and Example 1 is that: the weight ratio of chrome corundum fire clay to water glass is 12:1; the mixing time is 3 min.

[0041] Among the fillers in Examples 1 - 5, when the weight ratio of chrome corundum fire clay to water glass is 8:1, after the chrome corundum fire clay and water glass are mixed evenly, the viscosity is relatively low, and a longer mixing time is required to reach the state of flowing down when held by hand; when the weight ratio is 12:1, after the chrome corundum fire clay and water glass are mixed evenly, the viscosity is relatively high, and during the filling process, the compactness is slightly insufficient. And the mixing time of the filler in Example 3 is shorter and the viscosity is moderate. After multiple tests, the ratio of 10:1 in Example 3 is finally determined as the best ratio.

[0042] Example 6

[0043] Such as Figure 2As shown in the figure, a tundish monoblock nozzle 3 that can inhibit oxidation is fixed at the nozzle installation hole 1 at the bottom of the tundish. The tundish includes a tundish body 2 for containing molten steel, and a nozzle installation hole 1 for installing the monoblock nozzle 3 is provided at the bottom of the tundish body 2.

[0044] The monoblock nozzle 3 is a refractory member with upper and lower openings for guiding molten steel to flow out, and is made of aluminum-carbon refractory. Its upper end is inserted into the tundish body 2 through the nozzle installation hole 1 and extends downward from the bottom of the tundish body 2.

[0045] The diameter of the monoblock nozzle 3 at the connection with the tundish body 2 is smaller than that of other parts of the monoblock nozzle 3. Specifically, the diameter of the monoblock nozzle 3 decreases in a reducing manner from the top of the monoblock nozzle 3 to the connection with the tundish body 2, and gradually increases from the connection with the tundish body 2 to the bottom end of the monoblock nozzle 3. The outer diameter of the top end of the monoblock nozzle 3 is slightly smaller than the aperture of the nozzle installation hole 1, ensuring that the monoblock nozzle 3 can extend into the tundish body 2 from below the tundish body 2 through the nozzle installation hole 1. There is a gap 5 between the monoblock nozzle 3 and the tundish body 2, that is, there is a gap 5 between the outer wall of the part of the monoblock nozzle 3 connected to the tundish body 2 and the hole wall of the nozzle installation hole 1. The gap 5 is filled with the filler in Example 3, which is used to enhance the installation stability and sealing performance and prevent molten steel leakage.

[0046] The outside of the monoblock nozzle 3 is wrapped with a separation ring 4 from the top to the bottom wall position of the tundish body 2. The separation ring 4 is a frustum of a cone-shaped structure with upper and lower openings formed by combining two semi-circular structures. Its size matches the upper part of the monoblock nozzle 3, clamping the monoblock nozzle 3 and playing a role in limiting and auxiliary sealing. The contact surfaces between the two semi-circular structures of the separation ring 4 and the contact surfaces between the separation ring 4 and the monoblock nozzle 3 are sealed and connected by applying chrome corundum fire clay to enhance the sealing effect.

[0047] A construction and installation method for inhibiting oxidation of the above-mentioned tundish monoblock nozzle includes:

[0048] 1) Installation of the monoblock nozzle 3: When the monoblock nozzle 3 is installed and constructed in the continuous casting workshop of the steel plant, the operator transports the monoblock nozzle 3 to the bottom of the tundish repair bench, and manually sends the monoblock nozzle 3 into the tundish through the nozzle installation hole 1 at the bottom of the tundish.

[0049] 2) Separation ring 4 installation: The bottom construction workers of the tundish apply corundum fire clay to the joint surface of the two semi-circular structures of the separation ring 4 and the contact surface between the separation ring 4 and the integral nozzle 3 in advance. After the nozzle root extends out of the tundish bottom, the bottom construction workers clamp the separation ring 4 pre-coated with corundum fire clay to the nozzle root. The integral nozzle 3 is centered by using a level and a plumb bob method under the tundish bottom. During this period, the position of the integral nozzle 3 is adjusted and fixed by the bottom construction workers knocking on the separation ring 4.

[0050] 3) Plugging the holes at the bottom of the tundish: After the integral nozzle 3 is centered and fixedly installed, the gap 5 between the integral nozzle 3 and the hole wall of the nozzle installation hole 1 at the tundish bottom is filled. First, mix corundum fire clay and water glass (Na2O.nSiO2) in a ratio of 10:1 until it reaches a state where it can be held by hand without flowing. Then, the mixed filler is stuffed into the gap 5 between the integral nozzle 3 and the hole wall, and after stuffing tightly and filling it solidly, the excess filler is removed to complete the installation of the integral nozzle 3.

[0051] 4) After installation, let it stand for 24 hours, then bake the tundish for 3 hours and put it into production. The baking temperature is 1320 °C.

[0052] The service life of the tundish nozzle obtained by this scheme is 20 heats, and there is no phenomenon of nozzle root fracture. Under the existing technology, the tundish filled with corundum fire clay and water is prone to nozzle root fracture, so its service life is only 15 heats. After normal production stops pouring, the nozzle root is inspected and compared, and the improvement effect of the oxidation point at the nozzle root is significant.

[0053] It can be seen from this that for the integral nozzle installed by the method of the present invention, during use, the oxidation protection of the nozzle root is good, and there is no longer a phenomenon of nozzle fracture caused by oxidation at the nozzle root, improving the service life of the tundish and effectively supporting the stable and smooth production.

[0054] Other parts not described belong to the prior art.

Claims

1. A filler for suppressing oxidation of the tundish nozzle in continuous casting, characterized in that: It includes chrome corundum fireclay and water glass, and is used to fill the gap at the connection between the tundish body and the monolithic nozzle.

2. The filler according to claim 1, characterized in that: The weight ratio of the chrome corundum fireclay to the water glass is 8-12:

1.

3. The filler according to any one of claims 1 or 2, characterized in that: The weight ratio of the chrome corundum fireclay to the water glass is 10:

1.

4. The preparation method of the filler for inhibiting oxidation of the tundish submerged nozzle according to any one of claims 1 to 3, characterized in that: It includes mixing the chrome corundum fireclay and the water glass according to a set weight ratio.

5. The preparation method according to claim 4, characterized in that: The mixing time of the mixing process is 3-25 min.

6. A construction and installation method for inhibiting the oxidation of the tundish integral nozzle, characterized in that: It includes using a filler to fill and seal the gap at the connection between the tundish body and the monolithic nozzle; the filler is the filler for inhibiting oxidation of the monolithic nozzle of the continuous casting tundish described in any one of claims 1-3 or the filler prepared by the preparation method described in claim 4 or 5.

7. The construction and installation method according to claim 6, characterized in that: The gap is the gap between the inner wall of the nozzle installation hole on the tundish body for installing the monolithic nozzle and the outer wall of the monolithic nozzle.

8. The construction and installation method according to claim 6, characterized in that: The using method of the filler includes: mixing the chrome corundum fireclay and the water glass according to a set weight ratio until it does not flow when held by hand, and then stuffing it into the gap between the monolithic nozzle and the nozzle installation hole on the tundish body, so as to play a role in fixing the monolithic nozzle and preventing oxidation.

9. The construction and installation method according to any one of claims 6 to 8, characterized in that: The construction and installation method includes the following steps: 1) Installation of the monolithic nozzle; 2) Installation of the split ring; 3) Using a filler to fill and seal the gap at the connection between the tundish body and the monolithic nozzle.

10. The construction and installation method according to claim 9, characterized in that: The construction and installation method specifically includes: 1) Installation of the monolithic nozzle: Handling of the monolithic nozzle and alignment of the nozzle position Carry the monolithic nozzle to the lower part of the tundish to be constructed and installed, then extend the top of the nozzle into the tundish through the nozzle installation hole at the bottom of the tundish body and align it to ensure that the monolithic nozzle is vertically downward and in alignment; 2) Installation of the split ring After the root of the nozzle is fed into the nozzle installation hole, clamp the root of the nozzle with the split ring coated with chrome corundum fireclay at the bottom inside the tundish to fix and limit the monolithic nozzle, and tap the split ring to adjust the alignment position; 3) Sealing of the nozzle installation hole at the bottom of the tundish After the split ring is set, use a filler to fill and seal the gap between the monolithic nozzle and the inner wall of the nozzle installation hole at the bottom of the tundish body.

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