A method for producing an antimony ingot

Abstract

The present application relates to the field of metal material, specifically to a preparation method of antimony ingot, the mold is preheated, the mold is composed of mold base and release agent; the composition of the release agent contains phosphorus doped boron nitride nanotube; the molten antimony liquid is injected into the mold, and then cooled and demolded, the present application can prolong the service life of cast iron mold and improve the production efficiency of antimony ingot.

Description

Technical Field

[0001] This invention relates to the field of metallic materials, specifically to a method for preparing antimony ingots. Background Technology

[0002] Antimony, as an important strategic metal, is widely used in flame retardants, alloy materials, semiconductor devices, and chemical catalysts. In the industrial production of antimony, the casting of molten antimony is a key process for preparing standard antimony ingots. This process typically uses metal molds (such as cast iron molds or steel molds) to pour molten antimony into the preheated mold cavity. After cooling and solidification, the ingot is demolded to obtain the antimony ingot product.

[0003] However, significant thermal shock issues exist during antimony ingot casting. When molten antimony is suddenly injected into the mold cavity, the mold surface experiences drastic temperature gradient changes, resulting in severe thermal shock. Under the cyclic action of rapid heating and cooling, the surface layer and core of the mold experience uneven expansion due to temperature differences, generating enormous thermal stress. Repeated thermal cycles lead to thermal fatigue cracks on the mold surface, which gradually expand into through-cracks, reducing the average service life of the mold in antimony ingot production. Frequent mold replacements severely restrict production efficiency and increase production costs. Furthermore, at high temperatures, molten antimony tends to adhere to the mold, causing not only difficulty in demolding and poor surface quality of the antimony ingot, but also further exacerbating mold damage due to forced demolding.

[0004] To mitigate the aforementioned thermal shock issues, existing technologies primarily involve preheating the mold or applying a release agent. While mold preheating can reduce the temperature difference between the mold and the molten antimony, this method has limited effectiveness in mitigating thermal shock, and high-temperature preheating consumes a lot of energy and creates a harsh working environment.

[0005] Traditional mold release agents are mostly graphite-based coatings. Although they can isolate the antimony liquid from the mold substrate to a certain extent, they are prone to oxidation at high temperatures and have a high thermal conductivity. The heat is directly conducted to the mold, causing impact, which reduces the service life of the mold. Frequent mold replacements will also reduce production efficiency. Summary of the Invention

[0006] Purpose of the invention: In view of the above-mentioned technical problems, the present invention proposes a method for preparing antimony ingots.

[0007] The technical solution adopted is as follows: A method for preparing antimony ingots: The mold is preheated and consists of a mold base and a release agent; the release agent contains phosphorus-doped boron nitride nanotubes; molten antimony liquid is injected into the mold, and then cooled and demolded.

[0008] Furthermore, the mold preheating temperature is 100-300℃.

[0009] Furthermore, the composition of the release agent, in parts by weight, is as follows: 20-25 parts of phosphorus-doped boron nitride nanotubes, 65-75 parts of deionized water, 10-15 parts of binder, 1-2 parts of dispersant, and 0.1-0.5 parts of defoamer.

[0010] Furthermore, the preparation method of the phosphorus-doped boron nitride nanotubes is as follows: Boron oxide, ammonium dihydrogen phosphate and catalyst are mixed, ball-milled and dried, then heat-treated under a nitrogen atmosphere, and finally acid-washed, water-washed and dried.

[0011] Furthermore, the catalyst is nano-iron powder or nano-magnesium powder.

[0012] Furthermore, the mass ratio of boron oxide, ammonium dihydrogen phosphate and catalyst is 1:0.15-0.25:0.01-0.02.

[0013] Furthermore, the heat treatment temperature is ≥1250℃ and the heat treatment time is ≥5h.

[0014] Furthermore, the heat treatment is carried out under a nitrogen or ammonia atmosphere.

[0015] Furthermore, the binder is aluminum dihydrogen phosphate.

[0016] Furthermore, the cooling rate is 1-20℃ / min, and the product is demolded when cooled to below 200℃.

[0017] The beneficial effects of this invention are: This invention provides a method for preparing antimony ingots. Compared to hexagonal boron nitride nanosheets, boron nitride nanotubes have lower thermal conductivity. By replacing nitrogen atoms in the boron nitride lattice with phosphorus atoms, lattice distortion and defect sites are introduced. This doping effect produces two beneficial results: further reducing thermal conductivity and forming an effective thermal resistance barrier; the introduction of phosphorus disrupts the chemical inertness of the boron nitride crystal planes, and phosphorus atoms in phosphorus-doped boron nitride nanotubes can form covalent or coordinate bonds with aluminum dihydrogen phosphate, improving the interfacial bonding force between the two. This results in a more compact and dense structure after the release agent is applied, reducing damage during the demolding process and increasing the number of times the antimony ingot can be continuously demolded. The hollow structure of phosphorus-doped boron nitride nanotubes can strongly scatter phonon transmission, effectively reducing the thermal diffusivity coefficient. The nanotube network forms a multi-reflective interface, suppressing the transmission of high-temperature heat radiation, and the micro-deformation under thermal shock absorbs thermal stress, preventing crack initiation and propagation, and improving the thermal shock resistance of the mold. This method can extend the service life of cast iron molds and improve the production efficiency of antimony ingots. Attached Figure Description

[0018] Figure 1 The image shows a SEM image of the phosphorus-doped boron nitride nanotubes prepared in Example 1. Detailed Implementation

[0019] Unless otherwise specified in the examples, the conditions were performed under standard conditions or as recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products. Techniques not mentioned in this invention refer to existing technologies. Unless otherwise specified, the following examples and comparative examples are parallel experiments, using the same processing steps and parameters. Example 1:

[0020] A method for preparing antimony ingots: Boron oxide, ammonium dihydrogen phosphate, and catalyst nano-iron powder were added to the grinding jar of a planetary ball mill in a mass ratio of 1:0.2:0.015. The ball mill was set to a rotational speed of 280 r / min, and the jar temperature was controlled at around 15℃ under the cooling condition of a cold air blower. The milling was carried out for 12 hours by alternating forward and reverse rotation for 10 minutes each time. During the milling process, high-purity nitrogen was introduced into the grinding jar once every hour. After the milling was completed, the mixture was collected and placed in a tube furnace. Under a flowing ammonia atmosphere of 50 ml / min, the temperature was increased to 1250℃ at a rate of 10℃ / min and held for 5 hours. After furnace cooling to room temperature, the product was collected, washed successively with dilute hydrochloric acid and deionized water, and then dried to obtain phosphorus-doped boron nitride nanotubes. The SEM image is shown below. Figure 1 Weigh out phosphorus-doped boron nitride nanotubes, deionized water, aluminum dihydrogen phosphate, ammonium oleate dispersant, and SAG638 defoamer in a weight ratio of 23:70:12:1.5:0.25. Mix the phosphorus-doped boron nitride nanotubes, ammonium oleate, and deionized water, then grind and disperse them in a high-speed disperser for 10 hours. Add aluminum dihydrogen phosphate and SAG638 defoamer and continue stirring for 30 minutes to obtain the release agent. Apply the release agent to the inner surface of an HT250 gray cast iron mold using an air spray gun. Control the spray gun pressure at 0.3-0.5 MPa, maintain the spray gun 20-30 cm from the mold surface, and use a "cross-spray" method to ensure uniform coverage of the slurry without any missed areas or overlaps. The spray thickness is [missing information]. After spraying, let it stand at room temperature for 60 minutes, then dry it at 80℃ for 30 minutes. Preheat the HT250 gray cast iron mold sprayed with release agent to 200℃, pour molten antimony liquid at 680±10℃ into the mold, and then cool it to 200℃ at a rate of 10℃ / min to demold it. Example 2:

[0021] A method for preparing antimony ingots: Boron oxide, ammonium dihydrogen phosphate, and catalyst nano-iron powder were added to the grinding jar of a planetary ball mill in a mass ratio of 1:0.25:0.02. The ball mill was set to a rotational speed of 280 r / min, and the jar temperature was controlled at around 15°C under the cooling condition of a cold air blower. The ball milling was carried out for 12 hours by alternating forward and reverse rotation for 10 minutes each time. During the process, high-purity nitrogen gas was introduced into the grinding jar once every 1 hour. After the ball milling was completed, the mixture was collected and placed in a tube furnace. Under a flowing ammonia atmosphere of 50 ml / min, the temperature was increased to 1250°C at a rate of 10°C / min. After holding at this temperature for 5 hours, the furnace was cooled to room temperature and the product was collected. The product was washed with dilute hydrochloric acid and deionized water in sequence and then dried to obtain phosphorus-doped boron nitride nanotubes. Weigh out phosphorus-doped boron nitride nanotubes, deionized water, aluminum dihydrogen phosphate, ammonium oleate dispersant, and SAG638 defoamer in a weight ratio of 25:75:15:2:0.5. Mix the phosphorus-doped boron nitride nanotubes, ammonium oleate, and deionized water, then grind and disperse them in a high-speed disperser for 10 hours. Add aluminum dihydrogen phosphate and SAG638 defoamer and continue stirring for 30 minutes to obtain the release agent. Apply the release agent to the inner surface of an HT250 gray cast iron mold using an air spray gun. Control the spray gun pressure at 0.3-0.5 MPa, maintain the spray gun 20-30 cm above the mold surface, and use a "cross-spray" method to ensure uniform coverage of the slurry without any missed areas or overlaps. The spray thickness should be [missing information]. After spraying, let it stand at room temperature for 60 minutes, then dry it at 80℃ for 30 minutes. Preheat the HT250 gray cast iron mold coated with release agent to 300℃, pour molten antimony liquid at 680±10℃ into the mold, and then cool it to 200℃ at a rate of 10℃ / min to demold it. Example 3:

[0022] A method for preparing antimony ingots: Boron oxide, ammonium dihydrogen phosphate, and catalyst nano-iron powder were added to the grinding jar of a planetary ball mill in a mass ratio of 1:0.15:0.01. The ball mill was set to a rotational speed of 280 r / min, and the jar temperature was controlled at around 15°C under the cooling condition of a cold air blower. The ball milling was carried out for 12 hours by alternating forward and reverse rotation for 10 minutes each time. During the process, high-purity nitrogen gas was introduced into the grinding jar once every 1 hour. After the ball milling was completed, the mixture was collected and placed in a tube furnace. Under a flowing ammonia atmosphere of 50 ml / min, the temperature was increased to 1250°C at a rate of 10°C / min. After holding at this temperature for 5 hours, the furnace was cooled to room temperature and the product was collected. The product was washed with dilute hydrochloric acid and deionized water in sequence and then dried to obtain phosphorus-doped boron nitride nanotubes. Weigh out phosphorus-doped boron nitride nanotubes, deionized water, aluminum dihydrogen phosphate, ammonium oleate dispersant, and SAG638 defoamer in a weight ratio of 20:65:10:1:0.1. Mix the phosphorus-doped boron nitride nanotubes, ammonium oleate, and deionized water, then grind and disperse them in a high-speed disperser for 10 hours. Add aluminum dihydrogen phosphate and SAG638 defoamer and continue stirring for 30 minutes to obtain the release agent. Apply the release agent to the inner surface of an HT250 gray cast iron mold using an air spray gun. Control the spray gun pressure at 0.3-0.5 MPa, maintain the spray gun 20-30 cm from the mold surface, and use a "cross-spray" method to ensure uniform coverage of the slurry without any missed areas or overlaps. The spray thickness should be [missing information]. After spraying, let it stand at room temperature for 60 minutes, then dry it at 80℃ for 30 minutes. Preheat the HT250 gray cast iron mold coated with release agent to 100℃, pour molten antimony liquid at 680±10℃ into the mold, and then cool it to 200℃ at a rate of 10℃ / min to demold it. Example 4:

[0023] A method for preparing antimony ingots: Boron oxide, ammonium dihydrogen phosphate, and catalyst nano-iron powder were added to the grinding jar of a planetary ball mill in a mass ratio of 1:0.25:0.01. The ball mill was set to a rotational speed of 280 r / min, and the jar temperature was controlled at around 15°C under the cooling condition of a cold air blower. The ball milling was carried out for 12 hours by alternating forward and reverse rotation for 10 minutes each time. During the process, high-purity nitrogen gas was introduced into the grinding jar once every 1 hour. After the ball milling was completed, the mixture was collected and placed in a tube furnace. Under a flowing ammonia atmosphere of 50 ml / min, the temperature was increased to 1250°C at a rate of 10°C / min. After holding at this temperature for 5 hours, the furnace was cooled to room temperature and the product was collected. The product was washed with dilute hydrochloric acid and deionized water in sequence and then dried to obtain phosphorus-doped boron nitride nanotubes. Weigh out phosphorus-doped boron nitride nanotubes, deionized water, aluminum dihydrogen phosphate, ammonium oleate dispersant, and SAG638 defoamer in a weight ratio of 25:65:15:1:0.5. Mix the phosphorus-doped boron nitride nanotubes, ammonium oleate, and deionized water, then grind and disperse them in a high-speed disperser for 10 hours. Add aluminum dihydrogen phosphate and SAG638 defoamer and continue stirring for 30 minutes to obtain the release agent. Apply the release agent to the inner surface of an HT250 gray cast iron mold using an air spray gun. Control the spray gun pressure at 0.3-0.5 MPa, maintain the spray gun 20-30 cm above the mold surface, and use a "cross-spray" method to ensure uniform coverage of the slurry without any missed areas or overlaps. The spray thickness should be [missing information]. After spraying, let it stand at room temperature for 60 minutes, then dry it at 80℃ for 30 minutes. Preheat the HT250 gray cast iron mold coated with release agent to 100℃, pour molten antimony liquid at 680±10℃ into the mold, and then cool it to 200℃ at a rate of 10℃ / min to demold it. Example 5:

[0024] A method for preparing antimony ingots: Boron oxide, ammonium dihydrogen phosphate, and catalyst nano-iron powder were added to the grinding jar of a planetary ball mill in a mass ratio of 1:0.15:0.02. The ball mill was set to a rotational speed of 280 r / min, and the jar temperature was controlled at around 15°C under the cooling condition of a cold air blower. The ball milling was carried out for 12 hours by alternating forward and reverse rotation for 10 minutes each time. During the process, high-purity nitrogen gas was introduced into the grinding jar once every 1 hour. After the ball milling was completed, the mixture was collected and placed in a tube furnace. Under a flowing ammonia atmosphere of 50 ml / min, the temperature was increased to 1250°C at a rate of 10°C / min. After holding at this temperature for 5 hours, the furnace was cooled to room temperature and the product was collected. The product was washed with dilute hydrochloric acid and deionized water in sequence and then dried to obtain phosphorus-doped boron nitride nanotubes. Weigh out phosphorus-doped boron nitride nanotubes, deionized water, aluminum dihydrogen phosphate, ammonium oleate dispersant, and SAG638 defoamer in a weight ratio of 20:75:10:2:0.1. Mix the phosphorus-doped boron nitride nanotubes, ammonium oleate, and deionized water, then grind and disperse them in a high-speed disperser for 10 hours. Add aluminum dihydrogen phosphate and SAG638 defoamer and continue stirring for 30 minutes to obtain the release agent. Apply the release agent to the inner surface of an HT250 gray cast iron mold using an air spray gun. Control the spray gun pressure at 0.3-0.5 MPa, maintain the spray gun 20-30 cm above the mold surface, and use a "cross-spray" method to ensure uniform coverage of the slurry without any missed areas or overlaps. The spray thickness should be [missing information]. After spraying, let it stand at room temperature for 60 minutes, then dry it at 80℃ for 30 minutes. Preheat the HT250 gray cast iron mold coated with release agent to 300℃, pour molten antimony liquid at 680±10℃ into the mold, and then cool it to 200℃ at a rate of 10℃ / min to demold it.

[0025] Comparative Example 1: The method is basically the same as in Example 1, except that commercially available boron nitride nanotubes (Zhongke Leiming) are used instead of the self-made phosphorus-doped boron nitride nanotubes.

[0026] A method for preparing antimony ingots: Weigh commercially available boron nitride nanotubes (Zhongke Leiming), deionized water, aluminum dihydrogen phosphate, ammonium oleate dispersant, and SAG638 defoamer according to a weight ratio of 23:70:12:1.5:0.25. Mix the boron nitride nanotubes, ammonium oleate, and deionized water, then grind and disperse them using a high-speed disperser for 10 hours. Add aluminum dihydrogen phosphate and SAG638 defoamer and continue stirring for 30 minutes to obtain the release agent. Apply the release agent to the inner surface of an HT250 gray cast iron mold using an air spray gun. Control the spray gun pressure at 0.3-0.5 MPa, maintain the spray gun at a distance of 20-30 cm from the mold surface, and use a "cross-spray" method to ensure uniform coverage of the slurry without any missed areas or overlaps. The spray thickness should be [missing information]. After spraying, let it stand at room temperature for 60 minutes, then dry it at 80℃ for 30 minutes. Preheat the HT250 gray cast iron mold sprayed with release agent to 200℃, pour molten antimony liquid at 680±10℃ into the mold, and then cool it to 200℃ at a rate of 10℃ / min to demold it.

[0027] Comparative Example 2: The method is basically the same as in Example 1, except that commercially available hexagonal boron nitride nanosheets (Yamei Nano) are used instead of the self-made phosphorus-doped boron nitride nanotubes.

[0028] A method for preparing antimony ingots: Weigh commercially available hexagonal boron nitride nanosheets (Yamei Nano), deionized water, aluminum dihydrogen phosphate, ammonium oleate dispersant, and SAG638 defoamer according to a weight ratio of 23:70:12:1.5:0.25. Mix the hexagonal boron nitride nanosheets, ammonium oleate, and deionized water, then grind and disperse them using a high-speed disperser for 10 hours. Add aluminum dihydrogen phosphate and SAG638 defoamer and continue stirring for 30 minutes to obtain the release agent. Apply the release agent to the inner surface of an HT250 gray cast iron mold using an air spray gun. Control the spray gun pressure at 0.3-0.5 MPa, maintain the spray gun 20-30 cm from the mold surface, and use a "cross-spray" method to ensure uniform coverage of the slurry without any missed areas or overlaps. The spray thickness should be [missing information]. After spraying, let it stand at room temperature for 60 minutes, then dry it at 80℃ for 30 minutes. Preheat the HT250 gray cast iron mold sprayed with release agent to 200℃, pour molten antimony liquid at 680±10℃ into the mold, and then cool it to 200℃ at a rate of 10℃ / min to demold it.

[0029] Performance testing The release agents prepared in Examples 1-5 and Comparative Examples 1-2 were sprayed onto HT250 gray cast iron sheets measuring 10cm × 5cm × 1cm using an air spray gun, with a spray thickness of [missing information]. After spraying, the sample was placed at room temperature for 60 minutes, and then dried at 80℃ for 30 minutes to obtain the specimen. Molten antimony liquid at a temperature of 680±10℃ was poured onto the surface of the test piece and HT250 gray cast iron sheet respectively. After naturally cooling to room temperature, the force applied to peel it off the mold was tested with a force gauge, which is the demolding force. The number of demolding times with a demolding force of less than 20N was taken as the number of continuous demolding times.

[0030] Another sample and HT250 gray cast iron sheet were placed in a sintering furnace at 800℃ and kept at that temperature for 30 minutes. Then they were taken out and placed in an ice-water mixture at 0℃ to cool for 10 seconds. The thermal shock was repeated multiple times until macroscopic cracks appeared. The number of thermal shocks experienced by the sample before cracks appeared was recorded to characterize the effect of the release agent on the thermal shock resistance of the mold.

[0031] The test results are shown in Table 1 below: Table 1: As shown in Table 1 above, the release agent prepared by the present invention can effectively increase the number of times antimony ingots can be continuously demolded and improve the thermal shock resistance of the mold.

[0032] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing antimony ingots, characterized in that, The mold is preheated and consists of a mold base and a release agent; the release agent contains phosphorus-doped boron nitride nanotubes; molten antimony liquid is injected into the mold, and then cooled and demolded.

2. The method for preparing antimony ingots as described in claim 1, characterized in that, The mold preheating temperature is 100-300℃.

3. The method for preparing antimony ingots as described in claim 1, characterized in that, The composition of the release agent, by weight, is as follows: 20-25 parts of phosphorus-doped boron nitride nanotubes, 65-75 parts of deionized water, 10-15 parts of binder, 1-2 parts of dispersant, and 0.1-0.5 parts of defoamer.

4. The method for preparing antimony ingots as described in claim 3, characterized in that, The preparation method of the phosphorus-doped boron nitride nanotubes is as follows: Boron oxide, ammonium dihydrogen phosphate and catalyst are mixed, ball-milled and dried, then heat-treated under a nitrogen atmosphere, and finally acid-washed, water-washed and dried.

5. The method for preparing antimony ingots as described in claim 4, characterized in that, The catalyst is nano-iron powder or nano-magnesium powder.

6. The method for preparing antimony ingots as described in claim 4, characterized in that, The mass ratio of boron oxide, ammonium dihydrogen phosphate and catalyst is 1:0.15-0.25:0.01-0.

02.

7. The method for preparing antimony ingots as described in claim 4, characterized in that, Heat treatment temperature ≥1250℃, heat treatment time ≥5h.

8. The method for preparing antimony ingots as described in claim 4, characterized in that, The heat treatment is carried out under a nitrogen or ammonia atmosphere.

9. The method for preparing antimony ingots as described in claim 3, characterized in that, The binder is aluminum dihydrogen phosphate.

10. The method for preparing antimony ingots as described in claim 1, characterized in that, The cooling rate is 1-20℃ / min, and the product is demolded when cooled to below 200℃.

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