Method for manufacturing zirconia refractory by fusion casting and preparation method thereof

Abstract

This invention provides a method for manufacturing zirconium refractory materials by melting and casting, belonging to the technical field of melt-cast refractory materials. The refractory materials of this invention are sprues and slide plates, containing ZrO2, HfO2, CaO, MgO, Y2O3, Fe2O3, TiO2, Al2O3, and SiO2. This invention directly casts molten zirconium oxide at high temperatures into a high-temperature mold to produce zirconium sprues and slide plates. This simplifies the production process of zirconium sprues and slide plates and eliminates the high-temperature sintering energy consumption associated with pressing and sintering processes. The prepared zirconium sprues and slide plates have high bulk density, and the manufactured products exhibit uniform distribution of crystal phases and internal micropores, resulting in a significant improvement in hot compressive strength, thermal shock resistance, and erosion resistance.

Description

Technical Field

[0001] This invention relates to the field of fused casting refractory materials technology, and in particular to a fused casting method for manufacturing zirconium refractory materials and its preparation method. Background Technology

[0002] Currently, the zirconia nozzles and slide gates used in steel plants are produced using monoclinic zirconia or stabilized zirconia produced by the electrofusion method as the main raw materials, through processes of batching, pressing, and sintering. Zirconia nozzles and slide gates are key functional refractory components used in steelmaking operations to flow molten steel, with an annual consumption of approximately 100,000 tons.

[0003] Monoclinic zirconia produced by the electrofusion method uses zircon sand as the main raw material, adding a carbon reducing agent to remove silicon dioxide from the zircon sand in an electric arc furnace, producing electrofused monoclinic zirconia, also known as desilicationized zirconium. Stabilized zirconia produced by the electrofusion method uses zircon sand as the main raw material, adding a carbon reducing agent and a stabilizer to remove silicon dioxide from the zircon sand in an electric arc furnace, producing electrofused stabilized zirconia; or desilicationized zirconium can be mixed with a stabilizer and electrofused at high temperature in an electric arc furnace to produce electrofused stabilized zirconia. Zirconia has a very high melting point, at 2700℃, and producing one ton of electrofused zirconia requires 5000–8000 kWh of electricity, resulting in high energy consumption. The produced electrofused zirconia is crushed and processed into sand, fine powder, and micro powder of various particle sizes and supplied to refractory material manufacturers. Through batching, pressing, and high-temperature sintering, zirconia nozzles and slide plates are produced. The sintering temperature is 1680–1780℃, and the high-temperature holding time is 8–20 hours, resulting in high energy consumption. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a method for manufacturing zirconium refractory materials by melting and casting. The zirconium oxide raw material with stabilizers (CaO, MgO and Y2O3) is melted and stabilized in an electric arc furnace at high temperature to form a high-temperature melt of stabilized zirconium oxide. The high-temperature melt is then directly cast into a high-temperature mold to manufacture zirconium sprues and slide plates.

[0005] The zirconium refractory material manufactured by the casting method of this invention comprises the following chemical components in parts by weight:

[0006] ZrO2+HfO2: 90-97 parts, CaO: 0-4 parts, MgO: 0-4 parts, Y2O3: 0-7 parts, Fe2O3: 0-1 parts, TiO2: 0-1 parts, Al2O3: 0-1 parts, SiO2: 0-1 parts;

[0007] The sum of the weight parts of Fe2O3, TiO2, Al2O3 and SiO2 is 0 to 1.0 parts, excluding 0.

[0008] The refractory materials are sprue and slide plate.

[0009] Another object of the present invention is to provide a method for preparing zirconium refractory materials by melting and casting, comprising the following steps:

[0010] Step 1: Mixing: Thoroughly mix the zirconium source, calcium source, magnesium source and yttrium source to obtain a mixture;

[0011] Step 2: Melting: The mixture is added to an electric arc furnace at a casting rate of 200-400 kg / min for melting. The melting temperature is 2700-3000℃ and the melting time is 60-180 min. The mixture is fully melted to form a mixed molten liquid.

[0012] Step 3: Casting: The mixed molten liquid is poured into a high-temperature resistant mold, and the casting is completed;

[0013] Step 4: Demolding: After casting, leave the molten liquid in the high-temperature mold at room temperature until the surface solidifies, then demold.

[0014] Step 5: Cooling: After demolding, cool the product to room temperature;

[0015] Step Six: Heat Holding Annealing: After cooling, heat holding annealing is performed to produce high-performance cast zirconium refractory material.

[0016] Furthermore, the zircon source mentioned in step one is at least one of desilication zircon, zirconia, and chemical zircon, wherein the total mass ratio of ZrO2 and HfO2 in the zircon source is ≥98.5%, and the particle size of the zircon source is <60 mesh.

[0017] Furthermore, the calcium source mentioned in step one is calcite with a CaCO3 content of ≥54%; the particle size of the calcium source is <2mm.

[0018] Furthermore, the magnesium source mentioned in step one is magnesite ore with a MgCO3 content ≥ 45%; the particle size of the magnesium source is < 2 mm.

[0019] Furthermore, the yttrium source mentioned in step one is one or more of yttrium oxalate, yttrium carbonate, and yttrium oxide; the particle size of the yttrium source is <325 mesh.

[0020] Furthermore, the dwell time in step four is ≥1 minute, and the temperature is reduced to below 2200℃.

[0021] Furthermore, the cooling time in step five is 1 to 5 minutes, cooling down to 1800 to 2000°C.

[0022] Furthermore, in step six, the annealing rate is 5–20 °C / h, and the holding annealing temperature is 800–1100 °C.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] This invention provides a method for manufacturing zirconium refractory materials by melting and casting. The high-temperature molten zirconium oxide is directly poured into a high-temperature mold to produce zirconium sprues and slide plates. This method simplifies the production process of zirconium sprues and slide plates and eliminates the high-temperature sintering energy consumption of pressing and sintering processes. This is significant for energy conservation, emission reduction, and lower production costs.

[0025] This invention simplifies the manufacturing process of zirconium sprue nozzles and slide plates, reducing energy consumption and production costs. The manufactured cast zirconium sprue nozzles and slide plates have a higher bulk density than those produced by pressing and sintering processes. Therefore, the manufactured products exhibit a more uniform distribution of crystalline phases and internal micropores, resulting in a significant improvement in hot compressive strength, thermal shock resistance, and erosion resistance. Zirconium sprue nozzles and slide plates manufactured using the cast method are better suited for critical applications in high-temperature, erosion-resistant materials used for molten steel flow control in the steel industry. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating the preparation process of the zirconium refractory material of the present invention. Detailed Implementation

[0027] The present invention will be further described below with reference to the embodiments.

[0028] Example 1

[0029] A zirconium refractory material manufactured by a melting and casting method, comprising the following chemical components in parts by weight:

[0030] ZrO2+HfO2: 94.57 parts; CaO: 1.15 parts; MgO: 1.05 parts; Y2O3: 2.52 parts; Fe2O3: 0.05 parts; TiO2: 0.12 parts; Al2O3: 0.16 parts; SiO2: 0.38 parts.

[0031] The refractory materials are sprue and slide plate.

[0032] The preparation method for manufacturing zirconium refractory materials by the melting and casting method includes the following steps:

[0033] Step 1: Mixing: Mix the zirconium source, calcium source, magnesium source, and yttrium source thoroughly and evenly according to the target composition to obtain a mixture. The mixing time is 40 min and the mixing rate is 25 r / min. The zirconium source is desilicationized zirconium, and the total mass ratio of ZrO2 and HfO2 in the zirconium source is 98.9%. The particle size of the zirconium source is <80 mesh. The calcium source is calcite with a CaCO3 content of 55% and a particle size of <2 mm. The magnesium source is magnesite with a MgCO3 content of 45.8% and a particle size of <2 mm. The yttrium source is yttrium oxalate with a particle size of <325 mesh.

[0034] Step 2: Melting: Add the mixture from Step 1 to a 1000kg electric arc furnace for melting at 2900℃ for 120 minutes until the mixture is fully melted to form a mixed molten liquid.

[0035] Step 3: Casting: The mixed molten liquid is poured into the high-temperature mold at a casting rate of 280 kg / min. After casting is completed, the high-temperature mold is a graphite mold that can withstand temperatures above 3000℃.

[0036] Step 4: Demolding: Let the molten liquid poured in Step 3 stand at room temperature for 3 minutes until the surface of the molten liquid solidifies to a certain strength and the surface temperature is 2200℃ before demolding.

[0037] Step 5: Cooling: After demolding in Step 4 above, the product is cooled at room temperature. The cooling rate depends on the ambient temperature. In this invention, the cooling rate is 80℃ / min, the cooling time is 5min, and the product is cooled to 1800℃.

[0038] Step Six: Heating and Annealing: After cooling in Step Five above, the demolded casting is quickly placed into an annealing furnace or insulating material and annealed at a rate of 8℃ / h at a holding temperature of 900℃ to produce fused zirconium sprue and slide plate castings. The castings are then cut and ground to obtain the finished zirconium sprue and slide plate. The specific preparation process is as follows: Figure 1 .

[0039] Example 2

[0040] A zirconium refractory material manufactured by a melting and casting method, comprising the following chemical components in parts by weight:

[0041] ZrO2+HfO2: 95.44 parts; CaO: 1.65 parts; MgO: 1.10 parts; Y2O3: 1.22 parts; Fe2O3: 0.07 parts; TiO2: 0.06 parts; Al2O3: 0.03 parts; SiO2: 0.43 parts.

[0042] The refractory materials are sprue and slide plate.

[0043] The preparation method for manufacturing zirconium refractory materials by the melting and casting method includes the following steps:

[0044] Step 1: Mixing: The zircon, calcium, magnesium, and yttrium sources are thoroughly mixed according to the target composition to obtain a mixture. The mixing time is 50 min, and the mixing rate is 28 r / min. The zircon source is natural zirconite, with a total ZrO2 and HfO2 mass ratio of 99.2% and a particle size < 60 mesh. The calcium source is calcite with a CaCO3 content of 54.8% and a particle size < 2 mm. The magnesium source is magnesite with a MgCO3 content of 45.9% and a particle size < 2 mm. The yttrium source is yttrium carbonate with a particle size < 325 mesh.

[0045] Step 2: Melting: Add the mixture from Step 1 to a 1000kg electric arc furnace for melting at 2950℃ for 150 minutes until the mixture is fully melted to form a mixed molten liquid.

[0046] Step 3: Casting: The mixed molten liquid is poured into the high-temperature mold at a casting rate of 270 kg / min. After casting is completed, the high-temperature mold is a graphite mold that can withstand temperatures above 3000℃.

[0047] Step 4: Demolding: Let the molten liquid poured in Step 3 stand at room temperature for 3 minutes until the surface of the molten liquid solidifies to a certain strength and the surface temperature is 2200℃ before demolding.

[0048] Step 5: Cooling: After demolding in Step 4 above, the product is cooled at room temperature. The cooling rate depends on the ambient temperature. In this invention, the cooling rate is 100℃ / min, the cooling time is 3min, and the product is cooled to 1900℃.

[0049] Step Six: Heating Annealing: After cooling down in Step Five above, the demolded casting is quickly placed into an annealing furnace or insulation material and held for annealing at a rate of 10℃ / h. The holding annealing temperature is 1000℃, which produces fused zirconium gate and slide plate castings. The castings are then cut and ground to obtain the finished zirconium gate and slide plate.

[0050] Example 3

[0051] A zirconium refractory material manufactured by a melting and casting method, comprising the following chemical components in parts by weight:

[0052] ZrO2+HfO2: 96.73 parts; CaO: 2.65 parts; MgO: 0.10 parts; Y2O3: 0.32 parts; Fe2O3: 0.03 parts; TiO2: 0.01 parts; Al2O3: 0.03 parts; SiO2: 0.13 parts.

[0053] The refractory materials are sprue and slide plate.

[0054] The preparation method for manufacturing zirconium refractory materials by the melting and casting method includes the following steps:

[0055] Step 1: Mixing: Thoroughly mix the zirconium source, calcium source, magnesium source, and yttrium source according to the target composition to obtain a mixture. The mixing time is 60 min, and the mixing rate is 30 r / min. The zirconium source is chemical zirconium, with a total mass ratio of ZrO2 and HfO2 of 98.9% and a particle size <60 mesh. The calcium source is calcite with a CaCO3 content of 55.2% and a particle size <2 mm. The magnesium source is magnesite with a MgCO3 content of 45.9% and a particle size <2 mm. The yttrium source is yttrium oxide with a particle size <325 mesh.

[0056] Step 2: Melting: Add the mixture from Step 1 to a 1000kg electric arc furnace for melting at 2850℃ for 150 minutes until the mixture is fully melted to form a mixed molten liquid.

[0057] Step 3: Casting: The mixed molten liquid is poured into the high-temperature mold at a casting rate of 280 kg / min. After casting is completed, the high-temperature mold is a graphite mold that can withstand temperatures above 3000℃.

[0058] Step 4: Demolding: Let the molten liquid poured in Step 3 stand at room temperature for 3 minutes until the surface of the molten liquid solidifies to a certain strength and the surface temperature is 2000℃ before demolding.

[0059] Step 5: Cooling: After demolding in Step 4 above, the product is cooled at room temperature. The cooling rate depends on the ambient temperature. In this invention, the cooling rate is 90℃ / min, the cooling time is 2min, and the product is cooled to 1820℃.

[0060] Step Six: Heating Annealing: After cooling down in Step Five above, the demolded casting is quickly placed into an annealing furnace or insulation material and held for annealing at a rate of 12℃ / h. The holding annealing temperature is 980℃, which produces fused zirconium gate and slide plate castings. The castings are then cut and ground to obtain the finished zirconium gate and slide plate.

[0061] Example 4

[0062] A zirconium refractory material manufactured by a melting and casting method, comprising the following chemical components in parts by weight:

[0063] ZrO2+HfO2: 96.52 parts; CaO: 0.25 parts; MgO: 2.10 parts; Y2O3: 0.52 parts; Fe2O3: 0.06 parts; TiO2: 0.09 parts; Al2O3: 0.13 parts; SiO2: 0.33 parts.

[0064] The refractory materials are sprue and slide plate.

[0065] The preparation method for manufacturing zirconium refractory materials by the melting and casting method includes the following steps:

[0066] Step 1: Mixing: The zirconium source, calcium source, magnesium source, and yttrium source are thoroughly mixed according to the target composition to obtain a mixture. The mixing time is 55 min, and the mixing rate is 29 r / min. The zirconium source is a mixture of desilicationized zirconium and chemical zirconium in a 1:2 mass ratio, with a total ZrO2 and HfO2 mass ratio of 98.7% and a particle size <80 mesh. The calcium source is calcite with a CaCO3 content of 54.6% and a particle size <2 mm. The magnesium source is magnesite with a MgCO3 content of 45.7% and a particle size <2 mm. The yttrium source is a mixture of yttrium oxalate and yttrium oxide in a 1:2 mass ratio and a particle size <325 mesh.

[0067] Step 2: Melting: Add the mixture from Step 1 to a 1000kg electric arc furnace for melting at 2880℃ for 120 minutes until the mixture is fully melted to form a mixed molten liquid.

[0068] Step 3: Casting: The mixed molten liquid is poured into the high-temperature mold at a casting rate of 200-300 kg / min. After casting is completed, the high-temperature mold is a graphite mold that can withstand temperatures above 3000℃.

[0069] Step 4: Demolding: Let the molten liquid poured in Step 3 stand at room temperature for 3 minutes until the surface of the molten liquid solidifies to a certain strength and the surface temperature is 2150℃ before demolding.

[0070] Step 5: Cooling: After demolding in Step 4 above, the product is cooled at room temperature. The cooling rate depends on the ambient temperature. In this invention, the cooling rate is 110℃ / min, the cooling time is 3min, and the product is cooled to 1820℃.

[0071] Step Six: Heating Annealing: After cooling down in Step Five above, the demolded casting is quickly placed into an annealing furnace or insulation material and held for annealing at a rate of 15℃ / h. The holding annealing temperature is 1000℃, which produces fused zirconium gate and slide plate castings. The castings are then cut and ground to obtain the finished zirconium gate and slide plate.

[0072] Example 5

[0073] A zirconium refractory material manufactured by a melting and casting method, comprising the following chemical components in parts by weight:

[0074] ZrO2+HfO2: 94.58 parts; CaO: 0.25 parts; MgO: 0.10 parts; Y2O3: 4.38 parts; Fe2O3: 0.07 parts; TiO2: 0.11 parts; Al2O3: 0.13 parts; SiO2: 0.38 parts.

[0075] The refractory materials are sprue and slide plate.

[0076] The preparation method for manufacturing zirconium refractory materials by the melting and casting method includes the following steps:

[0077] Step 1: Mixing: The zirconium source, calcium source, magnesium source, and yttrium source are thoroughly mixed according to the target composition to obtain a mixture. The mixing time is 45 min, and the mixing rate is 29 r / min. The zirconium source is a mixture of desilicationized zircon and natural zircon in a 1:1 mass ratio, with a total ZrO2 and HfO2 mass ratio of 98.9% and a particle size <60 mesh. The calcium source is calcite with a CaCO3 content of 55.3% and a particle size <2 mm. The magnesium source is magnesite with a MgCO3 content of 46.2% and a particle size <2 mm. The yttrium source is a mixture of yttrium carbonate and yttrium oxide in a 1:1 mass ratio and a particle size <325 mesh.

[0078] Step 2: Melting: Add the mixture from Step 1 into an electric arc furnace for melting at 2920℃ for 120 minutes until the mixture is fully melted to form a mixed molten liquid;

[0079] Step 3: Casting: The mixed molten liquid is poured into the high-temperature mold at a casting rate of 260 kg / min. After casting is completed, the high-temperature mold is a graphite mold that can withstand temperatures above 3000℃.

[0080] Step 4: Demolding: Let the molten liquid poured in Step 3 stand at room temperature for 3 minutes until the surface of the molten liquid solidifies to a certain strength and the surface temperature is 2160℃ before demolding.

[0081] Step 5: Cooling: After demolding in Step 4 above, the product is cooled at room temperature. The cooling rate depends on the ambient temperature. In this invention, the cooling rate is 85℃ / min, the cooling time is 4min, and the product is cooled to 1820℃.

[0082] Step Six: Heating Annealing: After cooling down in Step Five above, the demolded casting is quickly placed into an annealing furnace or insulation material and held for annealing at a rate of 9℃ / h. The holding annealing temperature is 910℃, which produces fused zirconium gate and slide plate castings. The castings are then cut and ground to obtain the finished zirconium gate and slide plate.

[0083] Tests were conducted on the sprue and slide plate prepared by the casting method in Examples 1-5 of this invention, and the bulk density was higher than 5.8 g / cm³.3 .

[0084] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for manufacturing zirconium refractory materials by melting and casting, characterized in that, The refractory material comprises the following chemical components in parts by weight: ZrO2+HfO2: 90~97 parts, CaO: 0~4 parts, MgO: 0~4 parts, Y2O3: 0~7 parts, Fe2O3: 0~1 parts, TiO2: 0~1 parts, Al2O3: 0~1 parts, SiO2: 0~1 parts; wherein the contents of CaO, MgO, Y2O3, Fe2O3, TiO2, Al2O3, and SiO2 are all not 0; The sum of the weight parts of Fe2O3, TiO2, Al2O3 and SiO2 is 0 to 1.0 parts, excluding 0. The refractory material is a sprue and a slide plate; The method for preparing zirconium refractory materials by the melting and casting method includes the following steps: Step 1: Mixing: Thoroughly mix the zirconium source, calcium source, magnesium source and yttrium source to obtain a mixture; Step 2: Melting: The mixture is added to an electric arc furnace at a casting rate of 200-400 kg / min for melting. The melting temperature is 2700-3000℃ and the melting time is 60-180 min. The mixture is fully melted to form a mixed molten liquid. Step 3: Casting: The mixed molten liquid is poured into a high-temperature resistant mold, and the casting is completed; Step 4: Demolding: After casting, leave the molten liquid in the high-temperature mold at room temperature until the surface solidifies, then demold. Step 5: Cooling: After demolding, cool the product to room temperature; Step Six: Heat Holding Annealing: After cooling, heat holding annealing is performed to produce high-performance cast zirconium refractory material; The dwell time in step four is ≥1 minute, and the temperature is reduced to below 2200℃; The cooling time mentioned in step five is 1 to 5 minutes, cooling down to 1800 to 2000℃; In step six, the annealing rate is 5~20℃ / h, and the holding annealing temperature is 800~1100℃.

2. The method for manufacturing zirconium refractory materials by melting and casting according to claim 1, characterized in that, The zirconium source mentioned in step one is at least one of desilication zircon and zirconia, wherein the total mass ratio of ZrO2 and HfO2 in the zirconium source is ≥98.5%, and the particle size of the zirconium source is <60 mesh.

3. The method for manufacturing zirconium refractory materials by melting and casting according to claim 1, characterized in that, The calcium source mentioned in step one is calcite with a CaCO3 content of ≥54%; the particle size of the calcium source is <2mm.

4. The method for manufacturing zirconium refractory materials by melting and casting according to claim 1, characterized in that, The magnesium source mentioned in step one is magnesite ore with a MgCO3 content ≥ 45%; the particle size of the magnesium source is < 2 mm.

5. The method for manufacturing zirconium refractory materials by melting and casting according to claim 1, characterized in that, The yttrium source mentioned in step one is one or more of yttrium oxalate, yttrium carbonate, or yttrium oxide; the particle size of the yttrium source is <325 mesh.

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