Preparation method of refractory crucible for reducing nickel metal smelting adhesion and wall hanging

Abstract

The present invention belongs to the technical field of pure smelting preparation of metallic nickel for the electronics industry, and relates to a preparation method of a refractory crucible for reducing metallic nickel smelting adhesion and wall hanging, the method is by loading magnesia-alumina spinel sand and calcium oxide frit particles into a rubber mold with elasticity, a magnesia-alumina spinel-calcium oxide composite crucible blank is prepared by ramming, the rubber mold equipped with the composite crucible blank is subjected to cold isostatic pressing, the isostatic pressing applies a pressure range of 90MPa~120Mpa, a holding time of 15min~30min, and then high-temperature sintering is performed. The refractory crucible obtained has the advantages of high use temperature, simple process, low cost, etc., and is particularly suitable for use in the smelting preparation of pure metallic nickel.

Description

Technical Field

[0001] The invention belongs to the technical field of pure smelting preparation of nickel metal for the electronics industry, and relates to a method for preparing a composite refractory crucible which can reduce wall adhesion during nickel smelting, reduce crucible erosion, and improve material yield. Background Art

[0002] Pure nickel metal has good electrical conductivity, processing ductility, and corrosion resistance, and is widely used in the electronics industry and other fields. In recent years, the application of pure nickel metal strips and foils in new energy batteries and other fields has continued to expand, and the demand and product quality requirements have continued to increase. For example, the national standard stipulates that the total impurity content of pure nickel strips with a grade of pure nickel metal (such as N6) shall not exceed 0.5%wt. Due to the certain gap in production technology compared with foreign countries, China imports a large amount of pure nickel metal strips and foils for high-end fields such as aerospace and electronics. Therefore, it is necessary to improve the quality level of my country's pure nickel metal products as soon as possible and reduce production costs to meet domestic demand.

[0003] One of the primary manufacturing processes for nickel metal products used in the electronics industry is vacuum induction melting, and the crucible is a crucial component of the vacuum induction furnace. During this process, nickel metal must withstand not only various mechanical stresses but also the erosion of high-temperature molten metal. The quality of the crucible is directly related to the metallurgical quality, processing costs, and production safety of the product. Therefore, producing high-quality, long-lasting, high-performance refractory crucibles is fundamental to ensuring product quality.

[0004] Crucible materials are used at temperatures between 1550°C and 1750°C, requiring them to possess high high-temperature strength and stable physical and chemical properties. In high-temperature, high-vacuum environments, various metallurgical physical and chemical reactions occur between the crucible material, molten metal, slag, and gases. These reactions can easily lead to problems such as molten metal sticking to the wall, crucible erosion, and contamination of the molten steel. Furthermore, the crucible material must exhibit excellent thermal shock resistance. Thermal shock resistance refers to the ability of a refractory crucible to withstand rapid temperature changes without cracking. During use, the crucible is subjected to periodic heating and cooling cycles, which generate expansion and contraction stresses within the crucible. This can cause cracks in the crucible, leading to steel infiltration and destruction. Summary of the Invention

[0005] This invention addresses the need for high-quality pure nickel metal vacuum induction melting in the electronics industry and proposes a method for preparing a refractory crucible that reduces the risk of nickel metal sticking to the wall during melting. The refractory crucible produced by this method offers advantages such as high operating temperature, simple processing, and low cost. It is particularly well-suited for the production of products in the electronics industry, which require high-quality pure nickel strip. The crucible produced using this method can significantly improve the metallurgical quality of pure nickel metal products.

[0006] A method for preparing a refractory crucible capable of reducing the risk of nickel metal sticking to the wall during smelting, comprising: loading magnesia-alumina spinel sand and calcium oxide frit particles into an elastic rubber mold; preparing a magnesia-alumina spinel-calcium oxide composite crucible blank by ramming; and cold isostatically pressing the rubber mold containing the composite crucible blank, wherein the isostatic pressing pressure ranges from 90 MPa to 120 MPa and the pressure is maintained for 15 to 30 minutes; and then performing high-temperature sintering and inert gas packaging.

[0007] Preferably, in the process of preparing the magnesia-alumina spinel-calcium oxide composite crucible body, the outer layer of the crucible in contact with the rubber mold is paved with magnesia-alumina spinel sand with a thickness of 6mm to 10mm, and the inner wall of the crucible is paved with calcium oxide frit particles with a thickness of 20mm to 30mm.

[0008] Preferably, the calcium oxide frit particles contain calcium oxide content greater than 93%, magnesium oxide content 2-4%, aluminum oxide content 0.5-1%, and the remainder is impurities; and the particle size of the calcium oxide frit particles is less than 2 mm.

[0009] Preferably, the magnesia-alumina spinel sand is obtained by uniformly mixing magnesia-alumina spinel and boric acid, the mixing time is not less than 10 minutes, and the amount of boric acid added is 1-2% of the mass of the magnesia-alumina spinel.

[0010] Preferably, the magnesium oxide content in the magnesium-aluminum spinel is 75-80%, the aluminum oxide content is 20-25%, the silicon oxide content is less than 0.5%, and the rest is impurities.

[0011] Preferably, the magnesia-alumina spinel has a particle size of less than 1.5 mm.

[0012] Preferably, the high-temperature sintering temperature is 1400° C. to 1480° C., and the holding time is 5 h to 8 h.

[0013] The calcium oxide frit is preferably a granular material obtained by calcining limestone at high temperature, crushing it, and screening it. It can be purchased directly from the market. The crucible prepared has an operating temperature of up to 1850°C, exhibits excellent chemical stability at high temperatures, and is highly resistant to slag erosion, making it ideal for the preparation of high-purity metals with low sulfur content and low non-metallic inclusions.

[0014] Because the high-temperature alloy melt is alkaline during the induction furnace smelting process when a crucible is used in vacuum induction melting of pure nickel, the present invention selects a crucible material with a basicity close to that of the slag to resist chemical erosion by the slag, reduce the impact of chemical erosion, and extend the service life of the crucible. Furthermore, to improve the thermal shock resistance of the material, magnesium-aluminum spinel sand is used in combination to further reduce the thermal expansion coefficient of the crucible material and minimize volume changes at high temperatures. Although calcium oxide has strong water absorption, the combination of the two can also avoid the problem of calcium oxide crucibles being difficult to store at room temperature.

[0015] Preferably, the magnesia-alumina spinel is prepared by melting and sintering magnesia and alumina at high temperature in an industrial electric arc furnace.

[0016] The specific process of the preparation method of the refractory crucible for reducing the adhesion and wall sticking of nickel during smelting is as follows:

[0017] (1) Take calcium oxide frit particles, crush them and screen them to a particle size of less than 2 mm; wherein the calcium oxide content in the calcium oxide frit is

[0018] >93%, magnesium oxide content 2-4%, aluminum oxide content 0.5-1%;

[0019] (2) taking magnesia-alumina spinel, crushing and screening the spinel to a particle size of less than 1.5 mm; wherein the spinel has a magnesium oxide content of 75-80%, an aluminum oxide content of 20-25%, a silicon oxide content of less than 0.5%, and the remaining impurities; uniformly mixing the screened magnesia-alumina spinel with boric acid to obtain magnesia-alumina spinel sand, the mixing time being not less than 10 minutes, and the amount of boric acid added being 1-2% of the mass of the magnesia-alumina spinel;

[0020] (3) The uniformly mixed magnesium aluminum spinel sand and calcium oxide frit particles are placed into an elastic rubber mold, and a magnesium aluminum spinel-calcium oxide refractory composite crucible blank is prepared by ramming; wherein, the outer layer of the crucible in contact with the rubber mold is paved with magnesium aluminum spinel sand with a thickness of 6 mm to 10 mm, and the inner wall of the crucible is paved with calcium oxide frit particles with a thickness of 20 mm to 30 mm;

[0021] (4) isostatic pressing and densification; placing the rubber mold containing the magnesium aluminum spinel-calcium oxide refractory composite crucible blank in step (3) into a cold isostatic press for cold isostatic pressing; the isostatic pressing pressure range is 90MPa to 120Mpa, and the holding time is 15min to 30min;

[0022] (5) Inert gas packaging after high-temperature sintering; the high-temperature sintering temperature is 1400℃~1480℃, and the holding time is 5h~8h.

[0023] The present invention addresses the problems of traditional refractory crucibles being prone to sticking and clinging to the wall and affecting metallurgical quality during the smelting process of domestically produced pure nickel metal. By designing the composition and structure of a refractory composite crucible, a new crucible that is resistant to corrosion and not prone to sticking to the wall is prepared, thereby improving the quality of metallic nickel products used in the electronics industry.

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

[0025] ① Composite refractory crucible structure design; In combination with actual engineering problems, the composition and structure of the magnesia-alumina spinel-calcium oxide refractory composite crucible were designed. Among them, the outer layer of the crucible in contact with the rubber sleeve is paved with magnesia-alumina spinel sand with a thickness of about 6mm to 10mm, and the inner wall of the crucible is paved with calcium oxide sand, so as to prepare a composite crucible with higher outer layer strength and better inner layer resistance to slag erosion. In addition, the calcium oxide content in the calcium oxide frit is greater than 93%, the magnesium oxide content is 2-4%, and the aluminum oxide content is 0.5-1%; the magnesium oxide content in the spinel is 75-80%, the aluminum oxide content is 20-25%, and the silicon oxide content is less than 0.5%. Therefore, the present invention combines magnesia-alumina spinel sand with calcium oxide refractory material to make a crucible for metal nickel smelting, which can reduce the adhesion of metal nickel to the wall while improving the thermal shock resistance of the material and extending the service life of the crucible.

[0026] ② Isostatic pressing and densification. The rubber mold containing the magnesium-aluminum spinel-calcium oxide refractory material is placed in a cold isostatic press and formed. The isostatic pressing pressure ranges from 90 MPa to 120 MPa, and the holding time is 15 to 30 minutes. This increases the density of the crucible and helps extend the service life of the composite crucible.

[0027] The present invention combines the vacuum metallurgy technology of metal materials with the refractory crucible preparation technology. Aiming at the high-quality smelting demand of high-quality pure nickel metal, the present invention innovatively designs a refractory composite crucible for vacuum induction melting of metallic nickel. The obtained composite crucible has the advantages of high operating temperature, simple process and low cost, and is particularly suitable for the product needs of the electronics industry that have high requirements for the quality of pure nickel strips. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The inner wall of the crucible made of magnesium-aluminum spinel-calcium oxide composite refractory material after use in the embodiment of the present invention. DETAILED DESCRIPTION

[0029] The present invention is further explained by the following examples: Magnesium-aluminum spinel was purchased from Gongyi Zhijun Refractory Material Co., Ltd. Magnesium-aluminum spinel furnace lining material was purchased from Hebei Hongzhuang Environmental Protection Technology Co., Ltd. Calcium oxide frit was purchased from Hebei Hongzhuang Environmental Protection Technology Co., Ltd. Calcium oxide granules were purchased from Hebei Hongzhuang Environmental Protection Technology Co., Ltd.

[0030] Example 1: Refractory calcium oxide frit is crushed, and the calcium oxide frit is screened with a screen. The undersize material is selected and the particle size of the undersize material for preparing the crucible is 2 mm. The calcium oxide frit has a calcium oxide content of 94%, a magnesium oxide content of 2%, an aluminum oxide content of 0.5%, and the remaining impurities. The screened calcium oxide frit particles are vacuum-sealed with a vacuum degree of 1×10 -1 After crushing the magnesia-alumina spinel, it is screened using a mesh. The magnesia-alumina spinel undersize is selected for furnace lining material with a particle size of 1.5 mm and a magnesium oxide content of 75%, aluminum oxide 22%, and silicon oxide 0.5%. The screened magnesia-alumina spinel is evenly mixed with boric acid (H3BO3) for 15 minutes, with the boric acid addition amount being 1.5% of the magnesia-alumina spinel mass. The mixed sand is then placed into an elastic rubber mold and ramming is used to prepare a magnesia-alumina spinel-calcium oxide refractory composite crucible blank. The outer layer of the crucible, which contacts the rubber sleeve, is covered with magnesia-alumina spinel sand to a thickness of approximately 6 mm. The inner wall of the crucible is covered with calcium oxide frit particles to a thickness of 30 mm, resulting in a composite crucible with a high outer layer strength and improved inner layer resistance to slag erosion. The rubber mold containing the magnesia-alumina spinel-calcium oxide refractory is then placed in a cold isostatic press for cold isostatic pressing. The isostatic pressing pressure range is 90Mpa, and the holding time is 15 minutes. The composite crucible blank after isostatic pressing is placed in a high-temperature heat treatment furnace for high-temperature sintering at a sintering temperature of 1400℃ and a holding time of 5 hours. After sintering, the composite crucible is taken out of the furnace and inspected for its dimensions and quality. The density of the crucible material after isostatic pressing reaches 3.2g / cm 3 .

[0031] The qualified composite refractory crucible is placed in a plastic bag, filled with dry inert gas and sealed for standby use.

[0032] The crucible of the same capacity was loaded with 50 kg of nickel material and subjected to vacuum induction melting in a vacuum furnace. The comparison results are as follows:

[0033]

[0034]

[0035] Example 2:

[0036] The refractory calcium oxide frit was crushed and screened with a screen. The undersize material was selected and the particle size of the undersize material for preparing the crucible was 1.5 mm. The calcium oxide frit contained 95% calcium oxide, 4% magnesium oxide, 0.5% aluminum oxide, and the rest was impurities. The screened calcium oxide frit particles were vacuum sealed with a vacuum degree of 0.5×10 -1Pa; crush the magnesia-alumina spinel and screen it with a sieve; use the magnesia-alumina spinel furnace lining material undersize material for the preparation of the refractory crucible; the particle size requirement is 1.3mm, wherein the magnesium oxide content is 80%, the aluminum oxide content is 15%, the silicon oxide content is 0.5%, and the rest are impurities; the screened magnesia-alumina spinel is evenly mixed with boric acid (H3BO3) for 11 minutes, and the amount of boric acid added is 2% of the mass of the magnesia-alumina spinel; the evenly mixed sand material is placed into an elastic rubber mold, and a ramming process is used to prepare a magnesia-alumina spinel-calcium oxide refractory composite crucible blank. Among them, the outer layer of the crucible in contact with the rubber sleeve is paved with magnesia-alumina spinel sand with a thickness of about 10mm, while the inner wall of the crucible is paved with calcium oxide frit particles with a thickness of 20mm, to prepare a composite crucible with a higher outer layer strength and better inner layer resistance to slag erosion; the rubber mold packaged with the magnesia-alumina spinel-calcium oxide refractory material is placed in a cold isostatic press for cold isostatic pressing. The isostatic pressing pressure range is 120Mpa, and the holding time is 30min. The composite crucible blank after isostatic pressing is placed in a high-temperature heat treatment furnace for high-temperature sintering at a sintering temperature of 1480℃ and a holding time of 8h. After sintering, it is taken out of the furnace. The composite crucible after sintering is taken out of the furnace and inspected for its dimensions and quality. The density of the crucible material after isostatic pressing reaches 3.4g / cm 3 .

[0037] The qualified composite refractory crucible is placed in a plastic bag, filled with dry inert gas and sealed for standby use.

[0038] The crucible of the same capacity is loaded with 80 kg of nickel material. After vacuum induction melting in a vacuum furnace, the comparison results are as follows:

[0039]

[0040] According to the general vacuum induction melting process and furnace loading method, the metal nickel used in the electronics industry is melted. After melting and use, the composite crucible proposed by the present invention is as follows: Figure 1 As shown. Figure 1 It can be seen from the figure that after using the composite refractory crucible of the present invention, there is no phenomenon of adhesion or wall hanging on the inner wall.

[0041] Comparative Example 1

[0042] The remaining steps are the same as those in Example 2, except for the isostatic pressing conditions. The isostatic pressing pressure used in the crucible preparation is 60 MPa, the holding time is 30 min, and the density of the crucible material after isostatic pressing reaches 2.8 g / cm 3 The inner wall is easily corroded by nickel solution, which shortens the service life.

[0043] The crucible of the same capacity is loaded with 80 kg of nickel material. After vacuum induction melting in a vacuum furnace, the comparison results are as follows:

[0044]

[0045] Comparative Example 2

[0046] The remaining steps are the same as those in Example 2, except that the outer layer of the composite refractory crucible, magnesia-alumina spinel sand, is 20 mm thick, and the crucible has poor heat resistance.

[0047] The crucible of the same capacity is loaded with 80 kg of nickel material. After vacuum induction melting in a vacuum furnace, the comparison results are as follows:

[0048]

[0049] Comparative Example 3

[0050] The remaining steps were the same as in Example 2, except that the calcium oxide frit had a calcium oxide content of 95%, a magnesium oxide content of 4%, and an aluminum oxide content of 1%. The spinel frit had a magnesium oxide content of 81%, an aluminum oxide content of 18.7%, and a silicon oxide content of 0.3%. The resulting crucible had poor heat resistance and a short service life.

[0051] The crucible of the same capacity is loaded with 80 kg of nickel material. After vacuum induction melting in a vacuum furnace, the comparison results are as follows:

[0052]

Claims

1. A method for preparing a refractory crucible for reducing the adhesion and wall buildup of nickel during smelting, characterized in that The method comprises the following steps: placing magnesia-alumina spinel sand and calcium oxide frit particles into an elastic rubber mold, preparing a magnesia-alumina spinel-calcium oxide composite crucible blank by ramming, performing cold isostatic pressing on the rubber mold containing the composite crucible blank, applying an isostatic pressing pressure in the range of 90 MPa to 120 MPa and holding the pressure for 15 to 30 minutes, then performing high-temperature sintering and inert gas packaging; in the process of preparing the magnesia-alumina spinel-calcium oxide composite crucible blank, paving the outer layer of the crucible in contact with the rubber mold with magnesia-alumina spinel sand to a thickness of 6 mm to 10 mm The thickness of the calcium oxide frit particles laid on the inner wall of the crucible is 20mm to 30mm; the calcium oxide content of the calcium oxide frit particles is greater than 93%, the magnesium oxide content is 2-4%, and the aluminum oxide content is 0.5-1%; the particle size of the calcium oxide frit particles is less than 2mm; the magnesium aluminum spinel sand is obtained by uniformly mixing magnesium aluminum spinel and boric acid, the mixing time is not less than 10min, the amount of boric acid added is 1-2% of the mass of the magnesium aluminum spinel, the magnesium oxide content of the magnesium aluminum spinel is 75-80%, the aluminum oxide content is 20-25%, and the silicon oxide content is less than 0.5%.

2. The method for preparing a refractory crucible for reducing the adhesion of nickel metal during smelting according to claim 1, characterized in that The particle size of the magnesium-aluminum spinel described in the method is less than 1.5 mm.

3. The method for preparing a refractory crucible for reducing the adhesion of nickel metal during smelting according to claim 1, characterized in that The high-temperature sintering temperature of the method is 1400° C. to 1480° C., and the heat preservation time is 5 hours to 8 hours.

4. A method for preparing a refractory crucible for reducing nickel metal sticking to the wall during smelting according to claim 1, characterized in that The method comprises the following steps: (1) Take calcium oxide frit particles, crush them, and screen them to a particle size of less than 2 mm; wherein the calcium oxide content in the calcium oxide frit is greater than 93%, the magnesium oxide content is 2-4%, and the aluminum oxide content is 0.5-1%; (2) Take magnesium aluminum spinel, crush it and screen it to obtain a particle size of less than 1.5 mm; wherein the spinel contains 75-80% magnesium oxide, 15-25% aluminum oxide, less than 0.5% silicon oxide, and the rest are impurities; (3) The sieved magnesia-alumina spinel is uniformly mixed with boric acid to obtain magnesia-alumina spinel sand, the mixing time is not less than 10 minutes, and the amount of boric acid added is 1-2% of the mass of the magnesia-alumina spinel; the uniformly mixed magnesia-alumina spinel sand and calcium oxide frit particles are loaded into an elastic rubber mold, and a magnesia-alumina spinel-calcium oxide refractory composite crucible blank is prepared by ramming; wherein, the outer layer of the crucible in contact with the rubber mold is paved with magnesia-alumina spinel sand with a thickness of 6 mm to 10 mm, and the inner wall of the crucible is paved with calcium oxide frit particles with a thickness of 20 mm to 30 mm; (4) isostatic pressing and densification; the rubber mold containing the magnesia-alumina spinel-calcium oxide refractory composite crucible blank in step (3) is placed in a cold isostatic press for cold isostatic pressing; the isostatic pressing pressure range is 90 MPa to 120 MPa, and the holding time is 15 min to 30 min; (5) high-temperature sintering and inert gas packaging; the high-temperature sintering temperature is 1400°C to 1480°C, and the holding time is 5 h to 8 h.

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