High-efficiency energy-saving process for producing manganese balls

Abstract

The application belongs to the field of electrochemistry and particularly relates to a high-efficiency energy-saving manganese ball production process, which comprises the following steps: manganese powder is mixed with manganous oxide to obtain powder; water glass is added to the powder, and after being uniformly mixed, the powder is pressed and formed in a mold to obtain wet manganese balls; the wet manganese balls are heat treated to solidify and form pores to obtain manganese ball precursors; and the manganese ball precursors are nitrided in a nitrogen-containing atmosphere. The process can promote the nitriding process of the manganese balls, improve the uniformity of the temperature in the nitriding process, reduce the production cost, and improve the product quality.

Description

Technical Field

[0001] This invention belongs to the field of alloy materials technology, specifically relating to a high-efficiency and energy-saving manganese ball production process. Background Technology

[0002] Nitrogen is generally classified as an element harmful to steel. However, in some steel grades, nitrogen plays a beneficial role and should be artificially added to a higher content. In stainless steel, nitrogen can delay the precipitation of carbides, and has the effects of solid solution strengthening, dispersion strengthening, and grain refinement. It is an element that is conducive to the formation of a stable austenitic structure, and can significantly improve the macrostructure of steel, reduce the stacking fault energy and work hardening index; it can also improve strength, toughness, creep resistance, and corrosion resistance. Currently, there are two main nitrogen-adding processes for high-nitrogen steel: pressurizing the molten steel to increase nitrogen to form gas phase nitriding, or adding nitriding alloys such as manganese nitride, ferromanganese nitride, chromium nitride, and ferrochrome nitride to increase the nitrogen content. Although gas phase nitriding has low production costs, smelting high-nitrogen steel with nitrogen gas has disadvantages such as slow nitrogen addition rate, large fluctuations in nitrogen content, and difficulty in controlling nitrogen concentration. Therefore, adding nitriding alloys to smelt high-nitrogen steel is more practical. Among them, manganese nitride is a commonly used nitriding alloy. Based on product shape, manganese nitride can be divided into manganese nitride powder, manganese nitride flakes, and manganese nitride spheres. Manganese nitride powder and flakes do not require pressing into spheres, resulting in lower raw material costs compared to manganese nitride spheres. However, the nitriding process is more difficult to control, and manganese nitride is primarily supplied as spheres. However, there are also challenges to overcome in the preparation of manganese spheres. For example, because the reaction between manganese and nitrogen is exothermic, it can cause the temperature in the center of the manganese sphere to rise and melt, resulting in a "nitrogen release" phenomenon and causing localized low nitrogen content in the manganese nitride. How to control temperature changes to ensure a uniform distribution of nitrogen content in manganese nitride and improve the quality of manganese sphere products is an urgent problem to be solved. Summary of the Invention

[0003] This invention primarily provides a highly efficient and energy-saving manganese sphere production process to address the problem in existing technologies where there is a large difference in nitrogen content between the inside and outside of the manganese sphere, and the internal nitrogen content is relatively low, resulting in a low overall average nitrogen content level. The technical solution is as follows: A high-efficiency and energy-saving manganese ball production process includes the following steps: mixing manganese powder with manganese oxide to obtain powder; adding water glass to the powder, mixing evenly, and pressing it into shape in a mold to obtain wet manganese balls; heat-treating the wet manganese balls to solidify and create pores to obtain manganese ball precursors; and nitriding the manganese ball precursors in a nitrogen-containing atmosphere.

[0004] Furthermore, the manganese oxide accounts for 0.5-2% of the mass of the manganese powder; the mass ratio of the manganese powder to water glass is 1:0.02-0.05.

[0005] Furthermore, the particle size of the manganese powder is 0.5~3mm; the pressure of the nitrogen-containing atmosphere during nitriding is 0.4~0.8, and the temperature is 600~1000℃.

[0006] Furthermore, the wet manganese balls are heat-treated at 80~100℃ for 0.5~1.5h, and then heated to 130~170℃ at a rate of 2~8℃ / min for 1~2h to obtain the manganese ball precursor.

[0007] Furthermore, the water glass is azide-modified water glass; the preparation of the azide-modified water glass includes the following steps: preparing a 3-azidopropyltriethoxysilane ethanol solution; adding water to sodium silicate to prepare water glass; adding polyvinyl alcohol to the water glass and mixing evenly; then adding the 3-azidopropyltriethoxysilane ethanol solution while stirring, and stirring the reaction at 60~80℃ for 1~2h; adding ethanol to the system until precipitation no longer increases; collecting the precipitate and adding water to form a colloid to obtain azide-modified water glass.

[0008] Furthermore, the sodium silicate in the water glass has a mass concentration of 30-50%; the mass ratio of 3-azidopropyltriethoxysilane to sodium silicate is 1:1-3; and the mass ratio of water glass to polyvinyl alcohol is 15-30:1.

[0009] Furthermore, amide groups are grafted onto the surface of manganese oxide, and then it is mixed with manganese powder to obtain a powder.

[0010] Further, manganese oxide was activated; after activation, it was fully dispersed in anhydrous ethanol; an aminosilane coupling agent was added, and the mixture was refluxed for 10-20 hours; after cooling, the product was collected and thoroughly washed, and then vacuum dried to obtain amino-functionalized manganese oxide. Prepare an oxalic acid solution by adding sodium hydroxide to the oxalic acid solution and adjusting the pH of the system to 5.5-6.5 to obtain an oxalic acid reaction solution; disperse amino-functionalized manganese oxide in water, add the oxalic acid reaction solution, mix well, and then react at 30-40℃ for 16-24 h; wash the product thoroughly and dry it under vacuum to obtain grafted amide-group manganese oxide.

[0011] Furthermore, the mass ratio of the aminosilane coupling agent to the activated manganese oxide is 1:2~5; the mass ratio of the oxalic acid to the aminofunctionalized manganese oxide is 1:4~10.

[0012] Furthermore, the activation includes the following steps: placing manganese oxide in water, adding ammonia to adjust the pH of the system to weak alkalinity; stirring at room temperature for 0.5~1h, and thoroughly washing the precipitate to obtain activated manganese oxide.

[0013] By adopting the above scheme, the method of the present invention has the following advantages: 1. The production process of this invention involves incorporating manganese oxide into manganese powder and then nitriding them together. During the nitriding process, manganese oxide, which has a high thermal conductivity, carries away the heat generated by the reaction at the center of the manganese spheres, reducing the melting of manganese and making the nitriding more uniform.

[0014] 2. In the nitriding process of the present invention, the manganese oxide in the high-temperature zone at the center of the manganese ball is partially reduced to elemental manganese under the action of hydrogen. The newly generated elemental manganese increases the active sites participating in the nitriding reaction, accelerates the nitriding reaction rate, and further suppresses the "nitrogen release" phenomenon at the center of the manganese ball.

[0015] 3. The water glass used in the process of this invention has azide groups. During the curing process of manganese balls, the water glass and azide groups slowly decompose and release gas, forming stronger and more interconnected channels inside the manganese balls before complete curing. This allows the manganese balls to react more uniformly during nitriding and is more conducive to heat dissipation.

[0016] 4. This invention controls the solidification speed of water glass by gradient heating, thereby ensuring that the manganese ball has a certain structural strength during the formation of the channel, so as not to prevent the channel from being unable to form, nor to cause the channel to collapse and close after it is formed.

[0017] 5. The process of this invention involves grafting amide groups onto the surface of manganese oxide. These grafted amide groups are beneficial for capturing nitrogen-containing gases in the early stages of nitriding, improving mass transfer efficiency, nitriding efficiency, and uniformity. Furthermore, the grafted amide groups decompose thermally during nitriding, and the resulting gases can act as a nitrogen source to promote nitriding and facilitate heat transfer, resulting in a more balanced temperature inside and outside the manganese sphere.

[0018] 6. The process of this invention does not introduce other impurity ions. It promotes the nitriding process of manganese spheres through decomposable and vaporizable groups. The nitriding efficiency is high, the time is short, the cost is low, the product is purer, the nitrogen content is evenly distributed, and the quality is good. Attached Figure Description

[0019] Figure 1 This is a comparison diagram of the nitrogen content at different positions of the manganese balls in each embodiment and the comparative example. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1: (1) Manganese oxide was placed in water, and ammonia was added to adjust the pH of the system to 9.5; the mixture was stirred at room temperature for 40 min, and the precipitate was collected by centrifugation. The precipitate was washed with water and then washed with anhydrous ethanol to obtain activated manganese oxide; then it was fully dispersed in anhydrous ethanol; 0.3 times the amount of KH-550 as activated manganese oxide was added, and the mixture was refluxed for 16 h; after cooling, the product was collected and washed thoroughly, and then dried under vacuum to obtain amino-functionalized manganese oxide; (2) Prepare 100 mL of 18 g / L oxalic acid solution, add sodium hydroxide to the oxalic acid solution to adjust the pH of the system to 6, and obtain oxalic acid reaction solution; place 12 g of amino-functionalized manganese oxide in water and disperse it fully, add the oxalic acid reaction solution, mix evenly, and then react at 35 °C for 20 h; wash the product thoroughly and dry it under vacuum to obtain grafted amide-group manganese oxide; (3) Prepare 3-azidopropyltriethoxysilane ethanol solution; take sodium silicate with a mass twice that of 3-azidopropyltriethoxysilane and add an equal weight of water to make water glass; add 5% polyvinyl alcohol to the water glass and mix well; then add 3-azidopropyltriethoxysilane ethanol solution while stirring, and stir the reaction at 70°C for 1.5 h; add ethanol to the system until the precipitation no longer increases; collect the precipitate and add water to form a colloid to obtain azide-modified water glass; (4) Add 1% amidated manganese oxide to manganese powder with a particle size of 1.5 mm and mix to obtain powder; add 3% azide-modified water glass to the powder, mix evenly and press into shape in a mold to obtain 3 cm wet manganese balls; heat treat the wet manganese balls at 90℃ for 1 h, and then heat treat at 150℃ for 1.5 h at a rate of 5℃ / min to obtain manganese ball precursor; in a vacuum nitriding furnace, under a nitrogen pressure of 0.6 MPa, first hold at 400℃ for 1 h, and then hold at 850℃ for 3 h.

[0022] Example 2: The difference from Example 1 is as follows: (2) Prepare 100 mL of 18 g / L oxalic acid solution, add sodium hydroxide to the oxalic acid solution, adjust the pH of the system to 6, and obtain oxalic acid reaction solution; place 7 g of amino-functionalized manganese oxide in water and disperse it fully, add the oxalic acid reaction solution, mix evenly, and then react at 35 °C for 20 h; wash the product thoroughly and dry it under vacuum to obtain grafted amide-group manganese oxide.

[0023] Example 3: The difference from Example 1 is as follows: (2) Prepare 100 mL of 18 g / L oxalic acid solution, add sodium hydroxide to the oxalic acid solution to adjust the pH of the system to 6, and obtain oxalic acid reaction solution; place 16 g of amino-functionalized manganese oxide in water and disperse it fully, add the oxalic acid reaction solution, mix evenly, and then react at 35 °C for 20 h; wash the product thoroughly and dry it under vacuum to obtain grafted amide-group manganese oxide.

[0024] Example 4: The difference from Example 1 is as follows: (3) Prepare 3-azidopropyltriethoxysilane ethanol solution; take 3 times the mass of sodium silicate of 3-azidopropyltriethoxysilane and add an equal weight of water to make water glass; add 5% polyvinyl alcohol to the water glass and mix well; then add 3-azidopropyltriethoxysilane ethanol solution while stirring, and stir the reaction at 70°C for 1.5 h; add ethanol to the system until the precipitation no longer increases; collect the precipitate and add water to form a colloid to obtain azido-modified water glass.

[0025] Example 5: The difference from Example 1 is as follows: (4) Add 0.5% amidated manganese oxide to manganese powder with a particle size of 1.5 mm and mix to obtain powder; add 3% azide-modified water glass to the powder, mix evenly and press into shape in a mold to obtain wet manganese balls; heat treat the wet manganese balls at 90℃ for 1 h, and then heat treat at 150℃ for 1.5 h at a rate of 5℃ / min to obtain manganese ball precursor; in a vacuum nitriding furnace, under a nitrogen pressure of 0.6 MPa, first hold at 400℃ for 1 h, and then hold at 850℃ for 3 h.

[0026] Example 6: The difference from Example 1 is as follows: (4) Add 2% amidated manganese oxide to manganese powder with a particle size of 1.5 mm and mix to obtain powder; add 3% azide-modified water glass to the powder, mix evenly and press into shape in a mold to obtain wet manganese balls; heat treat the wet manganese balls at 90℃ for 1 h, and then heat treat at 150℃ for 1.5 h at a rate of 5℃ / min to obtain manganese ball precursor; in a vacuum nitriding furnace, under a nitrogen pressure of 0.6 MPa, first hold at 400℃ for 1 h, and then hold at 850℃ for 3 h.

[0027] Example 7: The difference from Example 1 is as follows: (4) Add 1% amidated manganese oxide to manganese powder with a particle size of 1.5 mm and mix to obtain powder; add 5% azide-modified water glass to the powder, mix evenly and press into shape in a mold to obtain wet manganese balls; heat treat the wet manganese balls at 90℃ for 1 h, and then heat treat at 150℃ for 1.5 h at a rate of 5℃ / min to obtain manganese ball precursor; in a vacuum nitriding furnace, under a nitrogen pressure of 0.6 MPa, first hold at 400℃ for 1 h, and then hold at 850℃ for 4 h.

[0028] Example 8: The difference from Example 1 is as follows: (4) Add 1% amidated manganese oxide to manganese powder with a particle size of 1.5 mm and mix to obtain powder; add 3% azide-modified water glass to the powder, mix evenly and press into shape in a mold to obtain wet manganese balls; heat treat the wet manganese balls at 90℃ for 1 h, and then heat treat at 150℃ for 1.5 h at a rate of 2℃ / min to obtain manganese ball precursor; in a vacuum nitriding furnace, under a nitrogen pressure of 0.6 MPa, first hold at 400℃ for 1 h, and then hold at 850℃ for 3 h.

[0029] Example 9: The difference from Example 1 is as follows: (4) Add 1% amidated manganese oxide to manganese powder with a particle size of 1.5 mm and mix to obtain powder; add 3% azide-modified water glass to the powder, mix evenly and press into shape in a mold to obtain wet manganese balls; heat treat the wet manganese balls at 90℃ for 1 h, and then heat treat at 150℃ for 1.5 h at a rate of 8℃ / min to obtain manganese ball precursor; in a vacuum nitriding furnace, under a nitrogen pressure of 0.6 MPa, first hold at 400℃ for 1 h, and then hold at 850℃ for 4 h.

[0030] Example 10: (1) Prepare 3-azidopropyltriethoxysilane ethanol solution; take sodium silicate with a mass twice that of 3-azidopropyltriethoxysilane and add an equal weight of water to make water glass; add 5% polyvinyl alcohol to the water glass and mix well; then add 3-azidopropyltriethoxysilane ethanol solution while stirring, and stir the reaction at 70°C for 1.5 h; add ethanol to the system until the precipitation no longer increases; collect the precipitate and add water to form a colloid to obtain azido-modified water glass; (2) Add 1% manganese oxide to manganese powder with a particle size of 1.5 mm and mix to obtain powder; add 3% azide-modified water glass to the powder, mix evenly and press into shape in a mold to obtain wet manganese balls; heat treat the wet manganese balls at 90℃ for 1 h, and then heat treat at 150℃ for 1.5 h at a rate of 5℃ / min to obtain manganese ball precursor; in a vacuum nitriding furnace, under a nitrogen pressure of 0.6 MPa, first hold at 400℃ for 1 h, and then hold at 850℃ for 3 h.

[0031] Comparative Example 1: The difference from Example 1 is that: The water glass is not modified.

[0032] Comparative Example 2: The difference from Example 1 is that: No manganese oxide is added.

[0033] Example Sample Performance Testing: Five manganese balls were randomly selected from each of the embodiments and comparative examples. The nitrogen content at the surface and center of the manganese balls prepared in each embodiment and comparative example was analyzed using an infrared nitrogen and oxygen analyzer. The final data were averaged, and the results are shown in Table 1 and... Figure 1 As shown. As can be seen from the table above, the nitrogen content of the manganese balls prepared by the method of the present invention is relatively uniform, and the average nitrogen content among the various embodiments is not significantly different, indicating that the process of the present invention can produce manganese ball products with stable and controllable nitrogen content. The difference in nitrogen content between the center and the surface of the embodiments of the present invention is also significantly smaller than that of the comparative examples, indicating that the overall nitrogen content of the manganese balls produced by the process of the present invention is relatively uniform, the degree of internal manganese melting is small, and the product quality is good.

[0034] Examples 2 and 3 show that when manganese oxide is functionalized with amides, the manganese spheres in Example 2, with more complete amidation, exhibit a more uniform degree of nitridation both inside and outside, significantly better than those in Example 3. This indicates that the amide groups grafted onto the manganese oxide are beneficial for improving the complete nitridation of the manganese spheres. In Example 4, when water glass was modified, the water glass content was higher than in Example 1, resulting in a greater difference in nitrogen content between the inside and outside. This indicates that grafting azide groups onto the water glass is beneficial for homogenizing the temperature inside and outside the manganese spheres during nitridation. The significant difference in nitrogen content between the inside and outside of Comparative Example 1, which did not modify with water glass, also proves this point. The difference in the content of amidated manganese oxide in Examples 5 and 6 caused a significant difference in the nitrogen content difference between the inside and outside of the manganese spheres. The difference in content was significantly greater in Example 5, which had a lower content. This indicates that amidated manganese oxide is beneficial for promoting nitridation inside the manganese spheres. Furthermore, the nitrogen content on the surface of Example 5 also decreased, indicating that amidated manganese oxide not only promotes temperature homogenization but also promotes the overall nitridation process. The manganese oxide in Example 10 was not modified by amidation, and its nitrogen content was significantly lower than that in Example 1, but significantly higher than that in Comparative Example 2, which did not contain manganese oxide.

[0035] Compared to Example 1, Example 7 used more azide-modified water glass, resulting in a smaller difference in the amount of nitriding inside and outside the manganese spheres. However, the overall nitrogen content decreased, indicating that azide-modified water glass helps reduce the temperature difference between the inside and outside of the manganese spheres during nitriding. However, due to the low melting point of sodium silicate and the high temperature of the nitriding reaction, sodium silicate may exist in a molten state in the later stages of nitriding, hindering nitriding and causing a decrease in the overall nitrogen content of the manganese spheres. Examples 8 and 9 showed different heating rates during the heat treatment and solidification of the manganese spheres to create pores, resulting in significant differences in the nitrogen content of the manganese spheres. Example 9, with its faster heating rate, had a significantly smaller difference in nitrogen content between the inside and outside than Example 8. However, during the experiment, the strength of the manganese spheres in Example 9 decreased significantly, exhibiting cracking, increased fragmentation, and poor roundness. The integrity of the manganese spheres decreased significantly, requiring a balance between the strength and nitrogen content of the manganese spheres to maintain product quality.

[0036] For those skilled in the art, various other corresponding changes and modifications can be made based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of this invention.

Claims

1. A highly efficient and energy-saving manganese ball production process, characterized in that, The process includes the following steps: grafting amide groups onto the surface of manganese oxide, then mixing it with manganese powder to obtain a powder; adding water glass to the powder, mixing it evenly, and pressing it into shape in a mold to obtain wet manganese spheres; heat-treating the wet manganese spheres to solidify and create pores to obtain a manganese sphere precursor; nitriding the manganese sphere precursor in a nitrogen-containing atmosphere; wherein the manganese oxide accounts for 0.5~2% of the mass of the manganese powder; the mass ratio of the manganese powder to the water glass is 1:0.02~0.05; and the water glass is azide-modified water glass.

2. The high-efficiency and energy-saving manganese ball production process according to claim 1, characterized in that, The manganese powder has a particle size of 0.5~3mm; the nitrogen-containing atmosphere during nitriding has a pressure of 0.4~0.8 and a temperature of 600~1000℃.

3. The high-efficiency and energy-saving manganese ball production process according to claim 1, characterized in that, Wet manganese balls are heat-treated at 80~100℃ for 0.5~1.5h, and then heated to 130~170℃ at a rate of 2~8℃ / min for 1~2h to obtain manganese ball precursor.

4. The high-efficiency and energy-saving manganese ball production process according to claim 1, characterized in that, The preparation of the azide-modified water glass includes the following steps: preparing a 3-azidopropyltriethoxysilane ethanol solution; adding water to sodium silicate to make water glass; adding polyvinyl alcohol to the water glass and mixing evenly; then adding the 3-azidopropyltriethoxysilane ethanol solution while stirring, and stirring the reaction at 60~80℃ for 1~2h; adding ethanol to the system until precipitation no longer increases; collecting the precipitate and adding water to form a colloid to obtain the azide-modified water glass.

5. The high-efficiency and energy-saving manganese ball production process according to claim 4, characterized in that, The sodium silicate in the water glass has a mass concentration of 30-50%; the mass ratio of 3-azidopropyltriethoxysilane to sodium silicate is 1:1-3; and the mass ratio of water glass to polyvinyl alcohol is 15-30:

1.

6. The high-efficiency and energy-saving manganese ball production process according to claim 1, characterized in that, Manganese oxide was activated; after activation, it was fully dispersed in anhydrous ethanol; an aminosilane coupling agent was added, and the mixture was refluxed for 10-20 h; after cooling, the product was collected, washed thoroughly, and dried under vacuum to obtain amino-functionalized manganese oxide. Prepare an oxalic acid solution by adding sodium hydroxide to the oxalic acid solution and adjusting the pH of the system to 5.5-6.5 to obtain an oxalic acid reaction solution; disperse amino-functionalized manganese oxide in water, add the oxalic acid reaction solution, mix well, and then react at 30-40℃ for 16-24 h; wash the product thoroughly and dry it under vacuum to obtain grafted amide-group manganese oxide.

7. The high-efficiency and energy-saving manganese ball production process according to claim 6, characterized in that, The mass ratio of the aminosilane coupling agent to the activated manganese oxide is 1:2~5; the mass ratio of the oxalic acid to the aminofunctionalized manganese oxide is 1:4~10.

8. The high-efficiency and energy-saving manganese ball production process according to claim 6, characterized in that, The activation The steps include: placing manganese oxide in water and adding ammonia to adjust the pH of the system to be weakly alkaline; Stir at room temperature for 0.5 to 1 hour, and wash the precipitate thoroughly to obtain activated manganese oxide.

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