Manufacturing method of high-alloy iron-based casting ceramic grate bar of sintering machine
By melting and casting high-temperature resistant ceramic sheets on high alloy cast iron substrates, the problem of insufficient performance of traditional grate strips in high-temperature environments is solved, and a higher service life and lower cost are achieved.
Patent Information
- Application Number
- CN202411694577.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-25
- Publication Date
- 2025-03-21
AI Technical Summary
Traditional high chromium cast iron grate bars show low high temperature mechanical properties and anti-oxidation corrosion properties in high temperature environments, resulting in short service life and high cost.
Cook high-temperature resistant ceramic sheets on high alloy cast iron substrates, select ceramic sheets with a temperature resistance of more than 1100°C, and cover ceramic sheets on the working surface of the grate bar to isolate high-temperature furnace gas and block high-temperature radiation.
It significantly improves the high-temperature mechanical properties and resistance to high-temperature oxidation and corrosion, extends the service life, reduces manufacturing costs, and reduces spare parts losses and labor intensity for workers.
Smart Images
Figure CN119657887A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of sintering machine equipment in iron and steel metallurgy, and in particular to a method for manufacturing a high-alloy cast iron-based molten-cast ceramic grate bar. Background Art
[0003] The grate bar is the primary accessory of the sintering machine trolley furnace in iron and steel metallurgical production. The upper part of the grate bar carries the ore, and the two ends are supported on the sintering machine trolley. The lower bent feet of the grate bar are hung on the trolley. On the one hand, it fixes the grate bar when the trolley is turned over to unload the material, so that it will not fall off; on the other hand, it plays a supporting and strengthening role when the top of the grate bar carries the ore under pressure, preventing the grate bar from bending and breaking.
[0004] The working environment of grate bars is harsh. First, the temperature is high and the temperature changes greatly: the temperature of sintered ore can reach 1100℃, and the temperature of grate bars is generally 800-1000℃. After unloading, the temperature of grate bars drops rapidly to 100-300℃, and the thermal vibration shock is large; secondly, grate bars bear the heavy pressure of sintered ore during high-temperature sintering; thirdly, grate bars also bear the erosion of high-temperature and high-speed powder-gas two-phase flow and the corrosion of CO, CO2, NOx, SO2 and water vapor in high-temperature flue gas; fourthly, grate bars also bear the impact and abrasive wear of sintered ore during loading and unloading.
[0005] It can be seen that the grate bars of the sintering machine trolley in the steel plant must not only have excellent high-temperature mechanical properties such as high-temperature strength and high-temperature toughness, but also have excellent resistance to high-temperature oxidation and corrosion to ensure the normal production and operation of the sintering machine.
[0006] In traditional technology, the material of grate bars is mainly made of alloy cast iron such as high-chromium cast iron. Due to the poor resistance to high-temperature oxidation corrosion and high-temperature mechanical properties of materials such as high-chromium cast iron, the service life of alloy cast iron grate bars is short (mostly around 12 to 18 months), which cannot meet the high performance, long life and low cost requirements of steel sintering production.
[0007] In order to improve the high-temperature mechanical properties and high-temperature oxidation and corrosion resistance of high-chromium cast iron grate bars, the prior art uses alumina / zirconia wear-resistant ceramic sheets to mechanically inlay and cover the surface of the grate bars, which can isolate heat radiation and improve the wear resistance, corrosion resistance and oxidation resistance of the high-chromium cast iron grate bar matrix. The mechanical inlay method used is to first plan away 3mm of material from the surface of the grate bar, then process an inverted V-shaped groove with a depth of 10mm; then, process an inverted V-shaped boss alumina / zirconia wear-resistant ceramic sheet corresponding to the inverted V-shaped groove; finally, the wear-resistant ceramic sheet is mechanically inlaid with the inverted V-shaped boss and the inverted V-shaped groove on the surface of the grate bar.
[0008] The above method of mechanically inlaying wear-resistant ceramic sheets on grate bars has the following defects: 1. Since the Cr content of high chromium cast iron grate bars is about 15%-28%, its hardness is generally HRC50-HRC63. The machining of such high-hardness hard materials is very difficult, and the requirements for heat treatment process and machining tools are extremely high. Not only is the machining process complicated, but the cost is also high; 2. Generally, the thickness of the material-bearing part of the top of the grate bar is about 26-32mm, and the bottom of the grate bar is thinner, generally about 16mm. If 3mm of material is planed off on both sides of the grate bar and then a 10mm deep inverted V-shaped groove is processed, the thickness of the grate bar base will be thinned, which will inevitably lead to deformation and fracture of the grate bar at high temperatures, reducing the reliability of the grate bar in high temperature environments. Summary of the invention
[0010] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a method for manufacturing high-alloy cast iron-based fused-cast ceramic grate bars with excellent high-temperature mechanical properties, high-temperature oxidation corrosion resistance, long service life and low manufacturing cost.
[0011] The invention discloses a high alloy cast iron based fused cast wear-resistant ceramic grate bar, comprising a grate bar high alloy cast iron matrix and a high temperature resistant ceramic sheet fused cast on the working surface of the grate bar matrix.
[0012] A method for manufacturing a high-alloy iron-based molten-cast ceramic grate bar for a sintering machine according to the present invention comprises the following steps: (1) Arrangement of ceramic tiles: When the grate bars are produced by the lost foam casting process, the high temperature resistant ceramic sheets 4 are pasted on the surface of the EPS foam solid mold of the grate bars using high temperature resistant glue, and the distance between the high temperature resistant ceramic sheets is 1 to 6 mm; after the high temperature resistant glue is cured, the EPS foam solid mold is dipped in refractory coating and dried; the foam solid mold with hanging material drying is buried in dry quartz sand and subjected to three-dimensional vibration molding; When the grate bars are produced by sand casting process, high temperature resistant ceramic sheets are pasted on the inner surface of the hardened grate bar sand mold cavity using high temperature resistant glue, and the distance between the high temperature resistant ceramic sheets is 1 to 6 mm; after the high temperature resistant glue is cured, the upper and lower sand boxes are combined; (2) Adding materials: Weigh the alloy cast iron charge according to the conventional proportion and add the charge in the following order: scrap steel --- ferroalloy --- deoxidizer --- ferroalloy --- deoxidizer; (3) Melting: The smelting is carried out in a medium frequency induction furnace with an alkaline lining, the smelting temperature is controlled at 1500-1600℃, and pouring is performed immediately after smelting; (4) Casting: The casting temperature is controlled at 1450~1580℃.
[0013] (5) Cleaning: The castings are polished and cleaned and can be used directly without heat treatment.
[0014] The above-mentioned method for manufacturing high-alloy iron-based fused-cast ceramic grate bars for a sintering machine, wherein the grate bars are made of high-chromium cast iron such as Cr22, Cr26, Cr28, aluminum-silicon heat-resistant cast iron, vermicular cast iron, or ductile cast iron.
[0015] The above-mentioned method for manufacturing high-alloy iron-based fused-cast ceramic grate bars for a sintering machine, wherein the material of the high-temperature resistant ceramic sheet 1 is alumina ceramic, silicon carbide ceramic, boron carbide ceramic, boron nitride ceramic or refractory metal boride, carbide ceramic material, which has a temperature resistance of more than 1100°C, a thickness of 1 to 6 mm, and a quadrilateral or hexagonal shape.
[0016] Compared with the prior art, the present invention has obvious beneficial effects. It can be seen from the above technical scheme that the present invention adopts the existing high-chromium cast iron and other alloy cast iron grate bar materials, melts and casts high-temperature resistant ceramic sheets on the working surface of the grate bar, and selects high-temperature resistant ceramic sheets with a temperature resistance of more than 1100°C, which can ensure that the ceramic sheets work normally under high-temperature sintering conditions. The interval between the high-temperature resistant ceramic sheets is 1 to 6 mm, which can ensure that when casting the grate bar casting, the high-temperature molten iron fills the interval gaps between the ceramic sheets, and the ceramic sheets can be clamped and clamped after the casting condenses and shrinks; if the ceramic sheet interval size is greater than 6 mm, the contact area between the alloy cast iron matrix and the sintering high-temperature furnace gas increases, expanding the scope of high-temperature oxidation corrosion. The present invention spreads the high-temperature ceramic sheets all over the working surface of the grate bar, isolates the direct scouring of the sintering high-temperature furnace gas on the alloy cast iron matrix of the grate bar, improves the high-temperature oxidation corrosion resistance of the alloy cast iron matrix of the grate bar, and prolongs the service life of the grate bar; at the same time, it blocks the damage of the alloy cast iron matrix of the grate bar by high-temperature radiation. The high-temperature ceramic sheets cast on the working surface of the grate bars have a heat-insulating effect. When the grate bars are cyclically heated or cooled during the operation of the sintering machine, the rate of heating or cooling of the grate bar matrix is slowed down, thereby enhancing the thermal shock resistance of the grate bars, improving the high-temperature mechanical properties of the grate bar alloy cast iron matrix, extending the service life of the grate bars, reducing the loss of spare parts and the labor intensity of workers, and reducing the cost of sintering production. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 It is a schematic diagram of the structure of the present invention in which the high temperature ceramic sheet is in a quadrilateral shape; Figure 2 for Figure 1 The main view of Figure 3 for Figure 1 A top view of Figure 4It is a schematic diagram of the structure of the present invention in which the high temperature ceramic sheet is hexagonal in shape; Figure 5 for Figure 4 The main view of Figure 6 for Figure 2 Top view of the .
[0019] Marked in the figure, 1. High temperature resistant ceramic sheet, 5. Cast iron base. DETAILED DESCRIPTION
[0021] In conjunction with the accompanying drawings and preferred embodiments, the specific implementation manner, structure, characteristics and efficacy of a method for manufacturing high-alloy iron-based molten-cast ceramic grate bars for a sintering machine proposed in accordance with the present invention are described in detail below.
[0022] Embodiment 1: A method for manufacturing a high-alloy iron-based molten-cast ceramic grate bar for a sintering machine comprises the following steps: 1. Material selection: (1) The material of the high alloy cast iron substrate 2 of the grate bar is Cr22 high chromium cast iron; (2) The high temperature resistant ceramic sheet 1 is made of 95% alumina ceramic, which has a temperature resistance of more than 1100°C, a thickness of 1mm, and a shape of a 10mm×10mm quadrilateral; 2. Modeling and arranging ceramic tiles: The high-alloy iron-based molten-cast ceramic grate bars are produced by the lost foam casting process. The high-temperature resistant ceramic sheets 1 are adhered to the outer surface of the EPS foam solid mold of the grate bars using high-temperature resistant glue, and the distance between all high-temperature resistant ceramic sheets 1 is 2mm; after the high-temperature resistant glue is cured, the EPS foam solid mold is dipped in refractory coating as a whole and dried; the dried foam solid mold is buried in a dry quartz sand sand box and prepared for casting through three-dimensional vibration molding.
[0023] 3. Add ingredients: Weigh the alloy cast iron charge according to the conventional proportion and add the materials in the following order: scrap steel --- ferroalloy --- deoxidizer --- ferroalloy --- deoxidizer.
[0024] 4. Melting: The smelting is carried out in a medium frequency induction furnace with an alkaline lining, the smelting temperature is controlled at 1580℃, and casting is performed immediately after smelting.
[0025] 5. Casting: The molten high-temperature molten iron is poured into the pouring riser of the grate bar EPS foam solid mold sand box, and the casting temperature is controlled at 1550℃.
[0026] 6. Cleaning: The castings are cleaned by sand removal and grinding and can be used directly without heat treatment.
[0027] Embodiment 2: A method for manufacturing a high-alloy iron-based molten-cast ceramic grate bar for a sintering machine comprises the following steps: 1. Material selection: (1) The material of the high alloy cast iron substrate 2 of the grate bar is Cr26 high chromium cast iron; (2) The high temperature resistant ceramic sheet 1 is made of silicon carbide ceramic, has a thickness of 3 mm, and has a hexagonal shape with a side length of 7 mm.
[0028] 2. Modeling and arranging ceramic tiles: The grate bars are produced by using a carbon dioxide hardened water glass sand mold casting process. The high temperature resistant ceramic sheets 1 are pasted on the inner surface of the hardened grate bar sand mold cavity using high temperature resistant glue. The distance between all high temperature resistant ceramic sheets 1 is 4 mm. After the high temperature resistant glue is cured, the upper and lower sand boxes are combined for casting.
[0029] 3. Add ingredients: Weigh the alloy cast iron charge in proportion and add in the following order: scrap steel --- ferroalloy --- deoxidizer --- ferroalloy --- deoxidizer.
[0030] 4. Melting: The smelting is carried out in a medium frequency induction furnace with an alkaline lining, the smelting temperature is controlled at 1550-1600℃, and pouring is performed immediately after smelting.
[0031] 5. Pouring: The molten high-temperature molten iron is poured into the pouring riser of the assembled grate bar mold cavity sand box, and the pouring temperature is controlled at 1550℃.
[0032] 6. Cleaning: The castings are polished and cleaned and can be used directly without heat treatment.
[0033] Embodiment 3: A method for manufacturing a high-alloy iron-based molten-cast ceramic grate bar for a sintering machine comprises the following steps: 1. Material selection: (1) The material of the high alloy cast iron substrate 2 of the grate bar is Cr28 high chromium cast iron; (2) The high temperature resistant ceramic sheet 1 is made of silicon carbide ceramic, has a thickness of 5 mm, and is a quadrilateral with a size of 10 mm × 10 mm.
[0034] 2. Modeling and arranging ceramic tiles: The grate bars are produced by the coated sand mold casting process. The high-temperature resistant ceramic sheets 1 are pasted on the inner surface of the hardened grate bar sand mold cavity using high-temperature resistant glue. The distance between all high-temperature resistant ceramic sheets 1 is 5 mm. After the high-temperature resistant glue is cured, the upper and lower sand boxes are combined for casting.
[0035] 3. Add ingredients: Weigh the alloy cast iron charge in proportion and add in the following order: scrap steel --- ferroalloy --- deoxidizer --- ferroalloy --- deoxidizer.
[0036] 4. Melting: The smelting is carried out in a medium frequency induction furnace with an alkaline lining, the smelting temperature is controlled at 1550-1600℃, and casting is performed immediately after smelting.
[0037] 5. Casting: The molten high-temperature molten iron is poured into the pouring riser of the assembled grate sand model cavity sand box, and the casting temperature is controlled at 1550℃.
[0038] 6. Cleaning: The castings are polished and cleaned and can be used directly without heat treatment.
[0039] Test example: The actual service life of the high-alloy iron-based fused-cast ceramic grate bars of the sintering machine prepared in Examples 1-3 exceeds 36 months, which is much longer than that of ordinary high-chromium cast iron grate bars, and its high-temperature oxidation resistance is also better than that of ordinary high-chromium cast iron grate bars.
[0040] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still falls within the scope of the technical solution of the present invention.
Claims
1. A method for manufacturing a high alloy iron-based molten-cast ceramic grate bar for a sintering machine, comprising the following steps: (1) Arrangement of ceramic pieces: Arrange high temperature resistant ceramic sheets on the mold surface, with the distance between the high temperature resistant ceramic sheets being 1 to 6 mm; (2) Adding materials: Weigh the alloy cast iron charge according to the conventional proportion and add the charge in the following order: scrap steel --- ferroalloy --- deoxidizer --- ferroalloy --- deoxidizer; (3) Melting: The smelting is carried out in a medium frequency induction furnace with an alkaline lining, the smelting temperature is controlled at 1500-1600℃, and pouring is performed immediately after smelting; (4) Casting: The casting temperature is controlled at 1450~1580℃; (5) Cleaning: The casting is polished and cleaned; (1) Arrange the ceramic tiles.
2. A method for manufacturing a high-alloy iron-based molten-cast ceramic grate bar for a sintering machine as described in claim 1, wherein the method for arranging ceramic sheets in step (1) is as follows: when the grate bars are produced by the lost foam casting process, the high-temperature resistant ceramic sheets 4 are adhered to the surface of the EPS foam solid mold of the grate bars using a high-temperature resistant adhesive, and the distance between the high-temperature resistant ceramic sheets is 1 to 6 mm; after the high-temperature resistant adhesive is cured, the EPS foam solid mold is dipped in a refractory coating as a whole and dried; the dried foam solid mold is buried in dry quartz sand and subjected to three-dimensional vibration molding.
3. A method for manufacturing a high-alloy iron-based fused-cast ceramic grate bar for a sintering machine as described in claim 1, wherein the method for arranging ceramic sheets in step (1) is as follows: when the grate bars are produced by a sand mold casting process, high-temperature resistant adhesive is used to stick the high-temperature resistant ceramic sheets to the inner surface of the hardened grate bar sand mold cavity, and the distance between the high-temperature resistant ceramic sheets is 1 to 6 mm; after the high-temperature resistant adhesive is cured, the upper and lower sand boxes are combined.
4. A method for manufacturing a high alloy iron-based fused-cast ceramic grate bar for a sintering machine according to any one of claims 1 to 3, wherein: The grate bars are made of high-chromium cast iron such as Cr22, Cr26, Cr28, aluminum-silicon heat-resistant cast iron, vermicular cast iron, ductile cast iron, and other high-alloy cast irons.
5. A method for manufacturing a high-alloy iron-based fused-cast ceramic grate bar for a sintering machine as described in any one of claims 1-3, wherein the material of the high-temperature resistant ceramic sheet 4 is alumina ceramic, silicon carbide ceramic, boron carbide ceramic, boron nitride ceramic or boride or carbide ceramic material of a refractory metal, and its temperature resistance exceeds 800°C.
6. A method for manufacturing high-alloy iron-based fused-cast ceramic grate bars for a sintering machine as claimed in any one of claims 1 to 3, wherein the thickness of the high-temperature resistant ceramic sheet 1 is 1 to 6 mm.
7. A method for manufacturing a high-alloy iron-based fused-cast ceramic grate bar for a sintering machine as claimed in any one of claims 1 to 3, wherein the shape of the high-temperature resistant ceramic sheet 4 is a quadrilateral or a hexagon.