Method for replacing center brick of spherical bottom ladle

Abstract

This invention discloses a method for replacing the center brick of a spherical-bottomed molten iron ladle, comprising the following steps: breaking and removing the original center brick in the bottom center area; breaking and removing the permanent layer material at the bottom of the original center brick, and cleaning the residue, residual iron, and residual ash in the bottom center area; pouring high-alumina castable into the permanent layer at the bottom of the original center brick, with the pouring height level with the unexcavated permanent layer at the joint, curing and initial setting; taking a new center brick, cutting at least one of the original center bricks, applying aluminum-magnesium-carbon mortar around the cut bricks and the surrounding area of ​​the complete center brick, and filling it into the bottom center area, ensuring that the gaps between bricks and between bricks and the unexcavated working layer at the joint do not exceed 1mm, and that the overall working surface and surrounding surface of the bottom center area are flat; and baking after curing. The method provided by this invention realizes the repair of frustum-shaped center bricks, which is simple, efficient, low-cost, and has a long service life after repair.

Description

Technical Field

[0001] This invention relates to the field of refractory materials for molten iron ladles, specifically to a method for replacing the center brick of a spherical-bottomed molten iron ladle. Background Technology

[0002] In iron and steel metallurgy, molten iron ladles are important containers for transporting and pre-treating molten iron. A spherical bottom is a structural feature of molten iron ladles, with the advantage that the non-working surface of the bottom working layer bricks is larger than the corresponding working surface, preventing the entire ladle from being pulled out due to thermal expansion and contraction. The bottom working layer is typically constructed by first laying a frustum-shaped center brick, with the other bottom bricks then laid in a ring around it. Because of its large size, the center brick is usually composed of four identical bricks assembled together.

[0003] With advancements in smelting technology, the central area at the bottom of some steel plants experiences increased erosion and corrosion from molten iron, making it unable to match the service life of other working lining areas. This necessitates mid-term repair and maintenance. Currently, two common bottom maintenance methods exist: the first involves cleaning residual iron from the bottom and then directly pouring matching castable refractory for repair; the second involves cleaning residual iron from the bottom, placing several erosion-resistant high-alumina bricks near the impact point in the central area, covering the high-alumina bricks with matching castable refractory, and then curing and baking before use. Both methods result in short service life after each maintenance, requiring multiple pours and repairs to achieve the desired lifespan matching the working lining bricks. Furthermore, each repair requires at least 24 hours of curing and baking before use, leading to excessively long repair cycles and impacting the turnover of molten iron ladles.

[0004] Therefore, there is an urgent need to develop a low-cost repair method with a long service life after repair to achieve the repair and maintenance of the center brick. Summary of the Invention

[0005] To overcome the shortcomings of the above-mentioned technologies, the purpose of this invention is to provide a method for replacing the center brick of a spherical bottom molten iron ladle. This method can realize the excavation and repair of the center brick of the spherical bottom molten iron ladle, and solve the problems of high maintenance and repair costs and short service life after maintenance and repair.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for replacing the center brick of a spherical-bottomed molten iron ladle, wherein the ladle is composed of an outer shell, a permanent layer, and a working layer from the outside to the inside, and the working layer in the central area of ​​the bottom of the ladle is made of a center brick; the center brick forms a frustum structure in the central area of ​​the bottom, and its special feature is that the replacement method includes the following steps:

[0008] 1) Break and remove the original center brick in the bottom center area;

[0009] 2) Break up and remove the permanent layer material at the bottom of the original center brick, and clean up the residue, iron residue, and ash residue in the center area at the bottom;

[0010] 3) Pour high-alumina castable into the permanent layer at the bottom of the original center brick, with the pouring height level with the unexcavated permanent layer at the joint, and allow it to cure for at least 8 hours and allow it to initially set.

[0011] 4) Take a new center brick, cut at least one of the center bricks, apply aluminum magnesium carbon mortar around the cut bricks and the whole center brick, and fill it into the bottom center area. Ensure that the gaps between each brick and between the brick and the unexcavated working layer of the joint are not more than 1mm, and that the overall working surface of the bottom center area and the surrounding surface are flat.

[0012] 5) After the initial conditioning, proceed with baking.

[0013] Furthermore, the center brick is a 1 / 4 frustum-shaped brick, and the top and bottom surfaces of the center brick are fan-shaped surfaces, with the bottom fan-shaped radius being larger than the top fan-shaped radius; the four center bricks can be spliced ​​together to form a frustum structure.

[0014] As a preferred embodiment, the high-alumina castable in step 3) is a high-alumina castable bonded with calcium aluminate cement.

[0015] Furthermore, the Al2O3 content in the high-alumina castable is 45-95%. The Al2O3 content needs to be at least 45% to ensure the refractoriness, mechanical properties and thermal shock resistance of the castable.

[0016] Furthermore, in step 3), before pouring the high-alumina castable, water is added to the high-alumina castable, and after stirring and mixing, the casting is carried out. After pouring, the surface of the castable is patted flat. The weight of water is 5 to 7% of the weight of the high-alumina castable.

[0017] As a preferred embodiment, in step 4), at least two of the center bricks are cut to form at least one cuboid brick. Since the working layer in the bottom center area has a frustum structure with a larger bottom diameter than the top, it is impossible to directly fill it with a complete center brick. Therefore, the center bricks need to be cut before filling. To avoid the situation where the center bricks cannot be filled even after cutting, it is ensured that at least one cuboid brick is among the bricks to be filled, which can be directly inserted into the bottom center area to achieve the replacement of the center bricks.

[0018] Furthermore, the rectangular bricks are filled into the bottom center area last.

[0019] Further, in step 4), after the cut bricks and the complete center brick coated with aluminum-magnesium-carbon mortar are filled into the bottom center area, the gaps are filled with aluminum-magnesium-carbon mortar to form an aluminum-magnesium-carbon mortar layer. The thickness of the aluminum-magnesium-carbon mortar layer between the bricks does not exceed 1 mm. When applying the aluminum-magnesium-carbon mortar, the coating thickness is 0.5 to 1.5 mm.

[0020] Furthermore, step 4) includes:

[0021] Take a central brick and cut it with the surface parallel to any of its trapezoidal sides as the first cutting surface to obtain a first irregular fan-shaped brick and a first brick. The first brick is an irregular cuboid brick with an arc surface.

[0022] Take the first irregular fan-shaped brick and cut it along the second cutting surface to obtain a second irregular fan-shaped brick and a second brick. The second cutting surface is perpendicular to the first cutting surface and the fan-shaped surface of the center brick. The second brick is an irregular cuboid brick with an arc surface. Take the second irregular fan-shaped brick and cut it to obtain a third brick. The third brick is a cuboid brick.

[0023] Take another central brick and cut it along a plane parallel to the first cutting surface to obtain a fourth brick, which is an irregular fan-shaped brick.

[0024] Take another center brick and cut it along a plane parallel to the second cutting plane to obtain a fifth brick, which is an irregular fan-shaped brick;

[0025] After applying aluminum-magnesium-carbon mortar to the four sides of the first brick, second brick, third brick, fourth brick, fifth brick, and two complete center bricks, the center brick area is filled in; wherein, the first brick and fourth brick are spliced ​​together to form the shape of a center brick, and the second brick, third brick, and fifth brick are spliced ​​together to form the shape of a center brick.

[0026] Furthermore, during the cutting process of the fourth brick, the width of the cut portion is not less than the width of the first brick, and the difference between the two widths is not greater than 1mm.

[0027] During the cutting process of the fifth brick, the width of the cut portion is not less than the width of the second brick and the side length of one side of the third brick, and the difference between the width of the cut portion and the width of the second brick and the side length of the third brick is not greater than 1mm; the other side length of the third brick is smaller than the total width of the first brick and the brick body lost during the cutting process and the difference is not greater than 1mm.

[0028] Furthermore, the cut portions of the fourth and fifth bricks are the same width.

[0029] Each cut during the cutting process results in a loss of 4-6mm in width. This excessive loss means that filling the entire gap with aluminum-magnesium-carbon mortar would lead to insufficient strength, affecting the lifespan of the repaired ladle. By precisely designing the cutting and splicing dimensions of multiple center bricks, the gap between the repaired center bricks is kept to no more than 1mm. Cutting multiple center bricks and splicing the cut portions avoids the problem of excessively large gaps after splicing due to the loss of bricks during the cutting process. This cutting method effectively maintains the gap between the repaired bricks to less than 1mm, and the deviation between the spliced ​​center bricks and the original center bricks is less than 1mm. It also solves the problem of not being able to repair center bricks that are truncated cone-shaped (smaller at the top, larger at the bottom).

[0030] Furthermore, the radius of the fan-shaped surface of the central brick 6 is 200-250 mm.

[0031] Furthermore, in step 4), during the cutting process of preparing the fourth and fifth bricks, the width of the cut portion is 50-60 mm. When it is less than 50 mm, the strength of the first and second bricks is too low, and they are easy to break during the splicing process. When it is greater than 60 mm, the fourth and fifth bricks are too small and not easy to splice.

[0032] As a preferred embodiment, the aluminum-magnesium-carbon mortar described in step 5) contains 50-80% Al2O3, 5-15% MgO, and 5-15% C. When the MgO content is below 5%, the mortar will not expand significantly; when it exceeds 15%, the expansion is excessive, both affecting the splicing of bricks. Therefore, a MgO content of 5-15% is chosen. When the C content is below 5%, the mortar cannot effectively resist penetration; when it exceeds 15%, its strength is too low, affecting its service life after repair.

[0033] Furthermore, in step 5), before applying the aluminum-magnesium-carbon mortar, the aluminum-magnesium-carbon mortar is mixed with water and stirred in a mixer to form a slurry before construction can proceed; the weight of the water is 25-45% of the weight of the aluminum-magnesium-carbon mortar.

[0034] As a preferred option, in step 5), the health maintenance time is 8 to 24 hours.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] This invention enables the excavation and repair of the central brick in a frustum shape. The method is simple, efficient, low-cost, and has a long service life after repair.

[0037] The cutting method used in this invention effectively solves the problem of excessive gaps caused by losses during the cutting process, and avoids the phenomenon of molten iron seeping into the gaps of the center brick when it is replaced, thus greatly improving the operational safety of the molten iron ladle. When repairing the center brick, this invention removes the permanent layer below the center brick and re-casts the refractory material, which provides support for the center brick and prevents displacement of the repaired center brick during use. This invention uses aluminum-magnesium-carbon mortar to fill the brick joints. On the one hand, the addition of carbon can effectively improve the resistance of the brick joints to molten iron erosion and penetration. On the other hand, the reaction of alumina and magnesium oxide at high temperature to produce spinel produces a certain expansion, which can further fill the brick joints and prevent iron seepage. Attached Figure Description

[0038] Figure 1 , Figure 2 , Figure 3 This is a schematic diagram of the cutting of the center brick in the embodiment;

[0039] Figure 4 This is a schematic diagram of the assembly of the center brick after cutting in the embodiment;

[0040] Figure 5 This is a cross-sectional schematic diagram of the bottom center brick of the molten iron ladle after the center brick of the spherical bottom ladle was replaced in the embodiment.

[0041] Marked in the diagram: 1. First brick; 2. Second brick; 3. Third brick; 4. Fourth brick; 5. Fifth brick; 6. Center brick; 8. Brick cutting loss; 9. Aluminum-magnesium-carbon mortar layer; 10. Bottom center area; 11. Bottom center permanent layer; 12. Circular area; 13. Unexcavated permanent layer. Detailed Implementation

[0042] To better explain the present invention, the main content of the invention is further illustrated below with reference to specific embodiments, but the content of the present invention is not limited to the following embodiments. The term "width" as used herein refers to the distance between two parallel lines on the top surface of the brick or between two parallel surfaces of the brick.

[0043] Example 1

[0044] like Figure 5As shown, the wall of the spherical-bottomed molten iron ladle consists of, from the outside in, an outer shell, a permanent layer, and a working layer. The working layer at the bottom of the ladle consists of a central area 10 and an annular area 12. The working layer in the central area 10 is a frustum structure, constructed by splicing four identical central bricks 6. Fan-shaped bricks are laid around the central bricks 6, forming the annular area 12 using a circular masonry method. The central bricks 6 are quarter-frustum shaped bricks, with their top and bottom surfaces being fan-shaped, and the radius of the bottom fan-shaped surface being larger than that of the top fan-shaped surface. This ladle bottom structure is existing technology. Due to the long-term erosion and intensified corrosion of the central area 10 by molten iron, it cannot achieve the same service life as the working linings in other areas, requiring repair and maintenance.

[0045] The following steps are taken to maintain the central area 10 at the bottom of the molten iron ladle using a method for replacing the central brick of a spherical bottom ladle according to the present invention:

[0046] 1) such as Figure 5 As shown, the original central brick of the bottom center area 10 of the spherical bottom molten iron ladle is broken and removed manually using a pneumatic pick, without damaging the bottom brick of the annular area 12 surrounding the central brick;

[0047] 2) Manually use a pneumatic pick to break up and remove the original permanent layer material below the bottom center area 10, and clean up the residue, iron residue and ash in the bottom center area 10.

[0048] 3) Pour a layer of high-alumina castable with calcium aluminate cement and an alumina content of 45% into the existing permanent layer below the bottom center area 10 to form the maintained bottom center permanent layer 11. The amount of water added during construction is 7% of the weight of the high-alumina castable. The high-alumina castable and water are mixed in a mixer before pouring. After pouring, use a shovel to flatten the surface of the castable so that the height of the bottom center permanent layer 11 is level with the permanent layer 13 that is not excavated at the connection. After curing for 8 hours and initial setting, the next step can be carried out.

[0049] 4) Take five center bricks 6, and cut three of them; the top fan-shaped surface of the center brick 6 has a radius of 200, and the bottom fan-shaped surface has a radius of 250mm.

[0050] like Figure 1As shown, a central brick 6 is cut along a first cutting plane parallel to a trapezoidal side of the central brick 6 to obtain a first brick 1, which is an irregular cuboid with an arc surface. The remaining irregular fan-shaped portion is then cut along a second cutting plane to obtain a second brick 2, which is perpendicular to both the first cutting plane and the fan-shaped surface of the central brick 6. The second brick 2 is also an irregular cuboid with an arc surface. Finally, the remaining portion is cut to obtain a third brick 3, which is a cuboid. The width of the first brick 1 is 49mm, the width of the second brick 2 is 49mm, and the width and length of the third brick 3 are 49mm and 53mm, respectively.

[0051] like Figure 2 As shown, a central brick 6 is cut along a plane parallel to the first cutting surface to obtain a fourth brick 4. The fourth brick 4 is an irregular fan-shaped brick, and the width of the cut portion is 50mm. There is brick loss 8 during the cutting process.

[0052] like Figure 3 As shown, a central brick 6 is cut along a plane parallel to the second cutting surface to obtain a fifth brick 5. The fifth brick 5 is an irregular fan-shaped brick, and the width of the cut portion is 50mm. There is brick loss 8 during the cutting process.

[0053] The width of the brick cutting loss 8 is 5mm.

[0054] Apply aluminum-magnesium-carbon mortar around the fifth brick (5), fourth brick (4), first brick (1), second brick (2), third brick (3), and two center bricks (6) to form an aluminum-magnesium-carbon mortar layer (9) between the brick joints. The aluminum-magnesium-carbon mortar has the following composition: Al2O3 content 50%, MgO content 15%, C content 15%, and the water added during construction is 32% of the weight of the aluminum-magnesium-carbon mortar.

[0055] Fill the bottom center area 10 with the bricks coated with aluminum-magnesium-carbon mortar, ensuring that the thickness of each gap (i.e., the aluminum-magnesium-carbon mortar layer 9) after assembly does not exceed 1mm, and that the overall working surface and surrounding surfaces of the working layer are flat; Figure 4 As shown, a fifth brick 5, a second brick 2, and a third brick 3 are filled into the central brick area to form the shape of a central brick 6. A fourth brick 4 and a first brick 1 are filled into the central brick area to form the shape of a central brick 6. The third brick 3 is the last one to be filled into the central brick area.

[0056] 5) After resting for 8 hours, bake for later use.

[0057] Example 2

[0058] The repair method in this embodiment is largely the same as that in Embodiment 1, except that:

[0059] In step 3), the alumina content in the high-alumina castable is 60%, the amount of water added during construction is 6% of the weight of the high-alumina castable, and the curing time is 12 hours.

[0060] In step 4), during the cutting process of preparing the fifth brick 5 and the fourth brick 4, the width of the cut-off portion is 60mm; the width of the first brick 1 is 59mm, the width of the second brick 2 is 59mm, and the width and length of the third brick 3 are 59mm and 63mm, respectively.

[0061] The composition of aluminum-magnesium-carbon mortar is: Al2O3 content 80%, MgO content 5%, C content 5%, and the amount of water added during construction is 28% of the weight of aluminum-magnesium-carbon mortar.

[0062] In step 6), the health maintenance time is 12 hours.

[0063] Example 3

[0064] The repair method in this embodiment is largely the same as that in Embodiment 1, except that:

[0065] In step 3), the alumina content in the high-alumina castable is 95%, the amount of water added during construction is 5% of the weight of the high-alumina castable, and the curing time is 24 hours.

[0066] In step 4), during the cutting process of preparing the fifth brick 5 and the fourth brick 4, the width of the cut portion is 50mm; the width of the first brick 1 is 49.5mm, the width of the second brick 2 is 49.5mm, and the width and length of the third brick 3 are 49.5mm and 53.5mm, respectively. The composition of the aluminum-magnesium-carbon mortar is: Al2O3 content 70%, MgO content 8%, C content 8%, and the amount of water added during construction is 28% of the weight of the aluminum-magnesium-carbon mortar.

[0067] In step 5), the health maintenance period is 24 hours.

[0068] Example 4

[0069] The repair method in this embodiment is largely the same as that in Embodiment 1, except that:

[0070] In step 3), the alumina content in the high-alumina castable is 65%, and the amount of water added during construction is 6.5% of the weight of the high-alumina castable.

[0071] In step 4), during the cutting process of preparing the fifth brick 5 and the fourth brick 4, the width of the cut portion is 55mm; the width of the first brick 1 is 54mm, the width of the second brick 2 is 54mm, and the width and length of the third brick 3 are 54mm and 58mm respectively. The composition of the aluminum-magnesium-carbon mortar is: Al2O3 content 60%, MgO content 12%, C content 12%, and the amount of water added during construction is 32% of the weight of the aluminum-magnesium-carbon mortar.

[0072] In step 5), the health maintenance period is 18 hours.

[0073] Example 5

[0074] The repair method in this embodiment is largely the same as that in Embodiment 1, except that:

[0075] In step 3), the alumina content in the high-alumina castable is 75%, and the amount of water added during construction is 5.5% of the weight of the high-alumina castable.

[0076] In step 4), during the cutting process of preparing the fifth brick 5 and the fourth brick 4, the width of the cut portion is 51mm; the width of the first brick 1 is 50mm, the width of the second brick 2 is 50mm, and the width and length of the third brick 3 are 50mm and 54mm respectively. The composition of the aluminum-magnesium-carbon mortar is: Al2O3 content 55%, MgO content 13%, C content 13%, and the amount of water added during construction is 37% of the weight of the aluminum-magnesium-carbon mortar.

[0077] In step 5), the health maintenance time is 16 hours.

[0078] The performance and cost of the spherical bottom molten iron ladles after repair in Examples 1 to 5 are shown in Table 1.

[0079] Table 1: Service life of the central area 10 at the bottom of the spherical bottom molten iron ladle in Examples 1-5 after repair

[0080] Average service life of furnace Cost, yuan / time Example 1 620 1000 Example 2 650 1100 Example 3 750 1200 Example 4 640 1050 Example 5 690 1150 Conventional castable repair 240 4000 Repair of high-alumina brick composite castable 400 5000

[0081] As shown in Table 1 above, the repair method designed in this invention costs less than one-third of ordinary casting repair, and the service life of the bottom center area after maintenance is more than 1.5 times longer than that of ordinary casting repair. Therefore, the excavation and patching method designed in this invention is beneficial for improving the service life of the repaired molten iron ladle bottom, and the cost of using this method is lower than that of conventional castable refractory repair and high-alumina brick composite castable refractory repair.

[0082] The above embodiments are merely best examples and are not intended to limit the implementation of the present invention. In addition to the above embodiments, the present invention has other embodiments. All technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope claimed by the present invention. Other parts not described are all prior art.

Claims

1. A method for replacing the center brick of a spherical-bottomed molten iron ladle, wherein the molten iron ladle is composed of an outer shell, a permanent layer, and a working layer from the outside to the inside, and the working layer in the central area of ​​the bottom of the molten iron ladle is made of a center brick; the center brick is a 1 / 4 frustum-shaped brick, and the center brick forms a frustum structure in the central area of ​​the bottom, characterized in that: The replacement method includes the following steps: 1) Break and remove the original center brick in the bottom center area; 2) Break up and remove the permanent layer material at the bottom of the original center brick, and clean up the residue, iron residue, and ash residue in the center area at the bottom; 3) Pour high-alumina castable into the permanent layer at the bottom of the original center brick, with the pouring height level with the permanent layer at the joint where no excavation or repair is required, and allow it to cure and initially set. 4) Take a new center brick, cut at least one of the center bricks, apply aluminum-magnesium-carbon mortar around the cut bricks and the complete center brick, and fill it into the bottom center area, ensuring that the gaps filled with aluminum-magnesium-carbon mortar between bricks and between bricks and the unexcavated working layer at the joints do not exceed 1mm, and that the overall working surface of the bottom center area and its surrounding surfaces are flat; including: Take a central brick and cut it with the surface parallel to any of its trapezoidal sides as the first cutting surface to obtain a first irregular fan-shaped brick and a first brick. The first brick is an irregular cuboid brick with an arc surface. Take the first irregular fan-shaped brick and cut it along the second cutting surface to obtain a second irregular fan-shaped brick and a second brick. The second cutting surface is perpendicular to the first cutting surface and the fan-shaped surface of the center brick. The second brick is an irregular cuboid brick with an arc surface. Take the second irregular fan-shaped brick and cut it to obtain a third brick. The third brick is a cuboid brick. Take another central brick and cut it along a plane parallel to the first cutting surface to obtain a fourth brick, which is an irregular fan-shaped brick. Take another center brick and cut it along a plane parallel to the second cutting plane to obtain a fifth brick, which is an irregular fan-shaped brick; After applying aluminum-magnesium-carbon mortar to the four sides of the first brick, second brick, third brick, fourth brick, fifth brick and two complete center bricks, the center brick area is filled in; wherein, the first brick and fourth brick are spliced ​​together to form the shape of a center brick, and the second brick, third brick and fifth brick are spliced ​​together to form the shape of a center brick. 5) Baking is done after the initial health maintenance.

2. The method for replacing the center brick of a spherical-bottomed molten iron ladle according to claim 1, characterized in that: The top and bottom surfaces of the central brick are fan-shaped, with the bottom fan radius being larger than the top fan radius; the four central bricks can be joined together to form a frustum structure.

3. The method for replacing the center brick of a spherical-bottomed molten iron ladle according to claim 1, characterized in that: The high-alumina castable mentioned in step 3) is a high-alumina castable bonded with calcium aluminate cement.

4. The method for replacing the center brick of the spherical-bottomed molten iron ladle according to claim 3, characterized in that: The Al2O3 content in the high-alumina castable is 45-95%.

5. The method for replacing the center brick of a spherical-bottomed molten iron ladle according to claim 4, characterized in that: In step 3), before pouring the high-alumina castable, water is added to the high-alumina castable, and after stirring and mixing, the casting is carried out. After pouring, the surface of the castable is patted flat. The weight of water is 5 to 7% of the weight of the high-alumina castable.

6. The method for replacing the center brick of a spherical-bottomed molten iron ladle according to claim 2, characterized in that: In step 4), at least two of the center bricks are cut to form at least one cuboid brick.

7. The method for replacing the center brick of a spherical-bottomed molten iron ladle according to claim 6, characterized in that: The rectangular bricks are filled into the bottom center area in the order that they are the last ones to be filled.

8. The method for replacing the center brick of a spherical-bottomed molten iron ladle according to claim 1, characterized in that: In step 4), the aluminum-magnesium-carbon mortar contains 50-80% Al2O3, 5-15% MgO, and 5-15% C.

9. The method for replacing the center brick of a spherical-bottomed molten iron ladle according to any one of claims 1 to 8, characterized in that: In step 4), before applying the aluminum-magnesium-carbon mortar, the aluminum-magnesium-carbon mortar is mixed with water and stirred into a slurry before construction; the weight of the water is 25-45% of the weight of the aluminum-magnesium-carbon mortar.

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