Production method of low-silicon low-aluminum tablet vanadium pentoxide

Abstract

The invention discloses a production method of low-silicon low-aluminum tablet vanadium pentoxide, which belongs to the technical field of vanadium chemical metallurgy, and comprises the following steps: (1) impurity removal of a vanadium liquid: heating the vanadium liquid with steam, and sequentially adding concentrated sulfuric acid and aluminum sulfate to obtain the purified vanadium liquid; (2) precipitating and filtering: adding liquid ammonium sulfate and concentrated sulfuric acid into the purified vanadium liquid to adjust the pH value, heating by steam, washing by a vertical filter press, extruding, and drying by compressed air to generate ammonium polyvanadate; and (3) drying, calcining and melting: carrying out flash evaporation drying on the ammonium polyvanadate, calcining in a calcining furnace, melting in a melting furnace, and carrying out sheet casting to generate the sheet-shaped vanadium pentoxide with the silicon content and the aluminum content being less than or equal to 0.05% by mass. By means of the method, impurities entering the product are reduced, and the flaky vanadium pentoxide meeting the requirement for aviation alloy smelting is produced.

Description

Technical Field

[0001] The invention belongs to the technical field of vanadium chemical metallurgy, and specifically relates to a method for producing vanadium pentoxide with low silicon and low aluminum tablets. Background Art

[0002] The traditional method of producing vanadium pentoxide tablets is sodium roasting of vanadium slag - purification of vanadium liquid calcium salt - ammonium salt precipitation method - melting and casting to obtain vanadium pentoxide tablets. After impurities are removed from the vanadium liquid calcium liquid, the silicon content is 400-500 mg / L. The ammonium salt precipitation method uses a step-by-step adjustment of the solution pH value to 1.9-2.3, adding ammonium salt precipitation, and filtering to precipitate ammonium polyvanadate. The obtained ammonium polyvanadate is heated at high temperature and melted to obtain melted vanadium pentoxide liquid, which is then cooled and cast into tablets.

[0003] The impurity content of vanadium pentoxide tablets obtained by ordinary vanadium liquid purification and impurity removal, ammonium salt precipitation method, belt filter or vertical filter press, and melting furnace melting process is relatively high, with Si content of about 0.1%-0.2% and Al content of 0.2-0.4%, which does not meet the requirements of vanadium pentoxide tablets for aviation alloy smelting. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for producing low-silicon and low-aluminum vanadium pentoxide tablets, which reduces the entry of impurities into the product and produces a product that meets the standards for vanadium pentoxide tablets for aviation alloy smelting.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: A method for producing low-silicon and low-aluminum vanadium pentoxide tablets comprises the following steps: (1) Impurity removal of vanadium liquid: The vanadium liquid is heated with steam, and concentrated sulfuric acid and aluminum sulfate are added in sequence to obtain purified vanadium liquid; (2) Sedimentation and filtration: Liquid ammonium sulfate and concentrated sulfuric acid are added to the purified vanadium liquid to adjust the pH, steam-heat it, wash it with water, squeeze it, and dry it with compressed air in a vertical filter press to generate ammonium polyvanadate; (3) Drying, calcining and melting: ammonium polyvanadate is flash dried, calcined in a calcining furnace, melted in a melting furnace and cast into tablets to produce vanadium pentoxide tablets.

[0006] Preferably, in step (1), the V content in the vanadium liquid is 22-28 g / L, the silicon content is 400-500 mg / L, the phosphorus content is 70-120 mg / L, and the temperature of the vanadium liquid after steam heating is 60-75° C. The pH of the purified vanadium liquid after adding concentrated sulfuric acid and aluminum sulfate is 5.5-6.5; The mass fraction of sulfuric acid in concentrated sulfuric acid is 92.5%-93.91%. After adding concentrated sulfuric acid, the pH of the vanadium solution is adjusted to 7.5-8.0; The amount of aluminum sulfate added is 0.14-0.2kg / m 3 Vanadium solution, after adding aluminum sulfate, the pH value of the vanadium solution is adjusted to 5.5-6.5.

[0007] Preferably, in step (1), in the purified vanadium liquid, the silicon content is ≤100 mg / L, the aluminum content is ≤20 mg / L, the phosphorus content is ≤1 mg / L, and the suspended matter content is ≤50 mg / L.

[0008] Preferably, in step (2), the amount of liquid ammonium sulfate added is 300-400 g / L, the pH is adjusted to 1.9-2.1 with 92.5%-93.91% concentrated sulfuric acid, and steam heated to 95-100°C; The extrusion pressure is 0.5-0.8MPa; The compressed air drying time is 200-400 seconds, and the compressed air pressure is 0.3-0.5MPa; The generated ammonium polyvanadate meets the following mass percentage conditions: V2O5≥88%, Al≤0.005%, Si≤0.02%.

[0009] Preferably, in step (3), the flash drying temperature of ammonium polyvanadate is 250-300°C, the hot air temperature of the calcining furnace is 550-600°C, and the outlet temperature is 390-400°C to obtain powdered vanadium pentoxide. The flash drying is instantaneous drying, and the calcining in the calcining furnace is instantaneous calcination.

[0010] Preferably, in step (3), the powdered vanadium pentoxide is sent to a melting furnace for melting, the temperature of the melting zone of the melting furnace is controlled at 750-800°C, and the mass percentages of silicon and aluminum in the vanadium pentoxide tablets are both ≤0.05%.

[0011] Preferably, in step (3), the flash drying is performed in a flash dryer, all parts of the flash dryer that contact the material are made of 304 and 316L stainless steel, the material of the annular seam is 310S, the wall thickness of the cylinder and the inner cone cylinder is more than 6 mm, and the thickness of the stirring blade is more than 14 mm; All parts of the calcining furnace that come into contact with materials are made of 304 and 316L stainless steel; Flash drying and calcining furnace calcination are both dusted by cyclone dust collectors. The material of the cyclone separator is 304 stainless steel with a wall thickness of not less than 4mm. The cyclone separator uses a bag dust collector to collect dust. The temperature resistance of the filter bag of the bag dust collector is ≥250℃.

[0012] Preferably, in step (3), the bottom of the melting furnace is a water-cooled cast iron bottom, on which a layer of Al2O3≥95% corundum is laid, the refractory material of the molten pool is built with Al2O3≥95% corundum, and the rest is LZ-75 grade high-alumina bricks; The negative pressure in the melting zone of the melting furnace is controlled at -20Pa~-50Pa.

[0013] Preferably, in step (3), the melting furnace consists of a melting zone, a heat preservation zone, a cooling zone and a settling zone; There are flat arch structures between the melting zone and the insulation zone. The material of the flat arch structure is Al2O3≥95% corundum material. High-alumina bricks are laid on the flat arch structure. The flat arch structure is 500-800mm away from the furnace bottom. The insulation area and the settlement area are separated by masonry walls, which are 800-1000mm away from the furnace top. The wall close to the settlement area is equipped with a steel pipe for cooling air. The temperature in the sedimentation zone is controlled at 250-300°C.

[0014] Preferably, in the step (3), a burner is provided on the melting furnace and arranged at the horizontal center of the rear wall, the burner is directly opposite to the flat arch structure, the discharge pipe of the melting furnace is made of 310S material, and the discharge point of the melting furnace is 1800-2200mm away from the discharge point.

[0015] The beneficial effects of adopting the above technical solution are: The method of the invention reduces the entry of impurities into the product, and produces tablet vanadium pentoxide with silicon and aluminum mass percentages of both ≤0.05% that meet the requirements for aviation alloy smelting. DETAILED DESCRIPTION

[0016] The present invention will be further described in detail below in conjunction with specific embodiments.

[0017] The embodiments and comparative examples were carried out in the following equipment: Flash drying is done in a flash dryer. All parts of the flash dryer that come into contact with materials are made of 304 stainless steel, the annular seam is made of 310S, the wall thickness of the cylinder and the inner cone cylinder is more than 6mm, and the thickness of the stirring blade is more than 14mm. All parts of the calcining furnace that come into contact with materials are made of 304 and 316L stainless steel; Flash drying and calcining furnace calcination are both dusted by cyclone dust collectors. The material of the cyclone separator is 304 stainless steel with a wall thickness of not less than 4mm. The cyclone separator uses a bag dust collector to collect dust. The temperature resistance of the filter bag of the bag dust collector is ≥250℃.

[0018] The bottom of the melting furnace is made of water-cooled cast iron, on which a layer of Al2O3≥95% corundum is laid. The refractory material of the molten pool is made of Al2O3≥95% corundum, and the rest is made of LZ-75 high-alumina bricks. The melting furnace consists of a melting zone, a heat preservation zone, a cooling zone and a settling zone; There are flat arch structures between the melting zone and the insulation zone. The material of the flat arch structure is Al2O3≥95% corundum. High-alumina bricks are laid on the flat arch structure. The flat arch structure is 600mm away from the furnace bottom. A partition wall is built between the insulation area and the settlement area. The partition wall is 9000mm away from the furnace top. A steel pipe for cooling air is installed on the partition wall close to the settlement area. The melting furnace is provided with a burner, which is arranged at the horizontal center of the rear wall. The burner is directly opposite to the flat arch structure. The material of the melting furnace discharge pipe is 310S, and the melting furnace discharge point is 2000mm away from the discharge point.

[0019] The parameters of the above equipment are not limited to those listed above and can be adjusted as needed in actual production. Example 1

[0020] (1) Removal of impurities from vanadium liquid; The V content of the vanadium liquid is 22g / L, the silicon content is 400mg / L, and the phosphorus content is 70mg / L. The temperature of the vanadium liquid after steam heating is 60°C. The pH is adjusted to 7.5 with 92.5% concentrated sulfuric acid, and then aluminum sulfate is added to adjust the pH to 5.5 to generate the purified vanadium liquid.

[0021] (2) Sedimentation and filtration; The silicon content of the purified vanadium liquid is 70mg / L, the aluminum content is 5mg / L, the phosphorus content is 0.5mg / L, and the suspended matter content is 30mg / L. The purified vanadium liquid is added with 300g / L of liquid ammonium sulfate and 92.5% concentrated sulfuric acid to adjust the pH to 2.1. Steam heating is performed to 100°C. The slurry is washed with water in a vertical filter press, squeezed at a pressure of 0.8MPa, and dried with compressed air for 300 seconds. After the compressed air pressure reaches 0.4MPa, the ammonium polyvanadate generated meets the following mass percentage conditions: V2O5 content is 89.2%, Al content is 0.003%, and Si content is 0.015%.

[0022] (3) Drying, calcining and melting; Ammonium polyvanadate is flash dried (250°C), calcined in a calcining furnace (inlet 550°C, outlet 395°C), melted in a melting furnace (-20Pa, melting zone temperature 800°C, settling zone temperature 300°C), and cast into sheets to generate vanadium pentoxide tablets with a silicon mass percentage of 0.035% and an aluminum mass percentage of 0.04%. Example 2

[0023] (1) Impurity removal of vanadium liquid; The V content of the vanadium liquid is 25g / L, the silicon content is 450mg / L, and the phosphorus content is 90mg / L. The temperature of the vanadium liquid after steam heating is 70°C. The pH is adjusted to 8 with 93.91% concentrated sulfuric acid, and then aluminum sulfate is added to adjust the pH to 6.5 to generate the purified vanadium liquid.

[0024] (2) Sedimentation and filtration; The purified vanadium liquid has a silicon content of 80 mg / L, an aluminum content of 10 mg / L, a phosphorus content of 0.7 mg / L, and a suspended solids content of 40 mg / L. The purified vanadium liquid is added with 350 g / L of liquid ammonium sulfate and 93.91% concentrated sulfuric acid to adjust the pH to 2.0. Steam is heated to 97°C. The slurry is washed with water in a vertical filter press, squeezed at a pressure of 0.5 MPa, and dried with compressed air for 200 seconds. After the compressed air pressure reaches 0.5 MPa, the ammonium polyvanadate generated meets the following mass percentage conditions: V2O5 content 88.8%, Al content 0.004%, Si content 0.018%.

[0025] (3) Drying, calcining and melting; High-purity ammonium metavanadate is flash dried (270°C), calcined in a calcining furnace (inlet 570°C, outlet 390°C), melted in a melting furnace (-30Pa, melting zone temperature 750°C, settling zone temperature 250°C), and cast into tablets to produce vanadium pentoxide tablets with a silicon mass percentage of 0.04% and an aluminum mass percentage of 0.045%. Example 3

[0026] (1) Impurity removal of vanadium liquid; The vanadium liquid contains 28g / L V, 500mg / L silicon, and 120mg / L phosphorus. The temperature of the vanadium liquid after steam heating is 75°C. The pH is adjusted to 7.5 with 92.89% concentrated sulfuric acid, and then aluminum sulfate is added to adjust the pH to 5.5 to generate the purified vanadium liquid.

[0027] (2) Sedimentation and filtration; The silicon content of the purified vanadium liquid is 100 mg / L, the aluminum content is 20 mg / L, the phosphorus content is 1 mg / L, and the suspended matter content is 50 mg / L. The purified vanadium liquid is added with 400 g / L of liquid ammonium sulfate and 92.89% concentrated sulfuric acid to adjust the pH to 1.9. Steam is heated to 95°C. The slurry is washed with water in a vertical filter press, squeezed at a pressure of 0.6 MPa, and dried with compressed air for 400 seconds. After the compressed air pressure reaches 0.3 MPa, the ammonium polyvanadate generated meets the following mass percentage conditions: V2O5 content 88.5%, Al content 0.005%, Si content 0.02%.

[0028] (3) Drying, calcining and melting; High-purity ammonium metavanadate is flash dried (300°C), calcined in a calcining furnace (inlet 600°C, outlet 400°C), melted in a melting furnace (-50Pa, melting zone temperature 780°C, settling zone temperature 280°C), and cast into tablets to produce vanadium pentoxide tablets with a silicon mass percentage of 0.05% and an aluminum mass percentage of 0.05%. Comparative Example 1

[0029] (1) Impurity removal of vanadium liquid; The V content of the vanadium liquid is 22g / L, the silicon content is 400mg / L, and the phosphorus content is 70mg / L. The temperature of the vanadium liquid after steam heating is 60°C. The pH is adjusted to 5.5 with 92.5% concentrated sulfuric acid, and then aluminum sulfate is added to adjust the pH to 2.1. The vanadium liquid cannot be purified. The silicon content of the vanadium liquid is 400mg / L, the phosphorus content is 70mg / L, and the impurities have not changed, which does not meet the next production conditions. Comparative Example 2

[0030] (1) Impurity removal of vanadium liquid; The V content of the vanadium liquid is 25g / L, the silicon content is 450mg / L, and the phosphorus content is 90mg / L. The temperature of the vanadium liquid after steam heating is 70°C. The pH is adjusted to 8 with 93.91% concentrated sulfuric acid, and then aluminum sulfate is added to adjust the pH to 6.5 to generate the purified vanadium liquid.

[0031] (2) Sedimentation and filtration; The silicon content of the purified vanadium liquid is 80mg / L, the aluminum content is 10mg / L, the phosphorus content is 0.7mg / L, and the suspended matter content is 40mg / L. The purified vanadium liquid is added with 350g / L of liquid ammonium sulfate and 93.91% concentrated sulfuric acid to adjust the pH to 1.5. Steam heating to 97°C. The slurry is washed with water in a vertical filter press, squeezed at 0.5MPa pressure, and dried with compressed air for 200 seconds. After the compressed air pressure reaches 0.5MPa, the ammonium polyvanadate generated meets the following mass percentage conditions: V2O5 content 80%, Al content 0.004%, Si content 0.018%. It does not meet the next step of production. Comparative Example 3

[0032] (1) Impurity removal of vanadium liquid; The vanadium liquid contains 28g / L V, 500mg / L silicon, and 120mg / L phosphorus. The temperature of the vanadium liquid after steam heating is 75°C. The pH is adjusted to 7.5 with 92.89% concentrated sulfuric acid, and then aluminum sulfate is added to adjust the pH to 5.5 to generate the purified vanadium liquid.

[0033] (2) Sedimentation and filtration; The silicon content of the purified vanadium liquid is 100 mg / L, the aluminum content is 20 mg / L, the phosphorus content is 1 mg / L, and the suspended matter content is 50 mg / L. The purified vanadium liquid is added with 400 g / L of liquid ammonium sulfate and 92.89% concentrated sulfuric acid to adjust the pH to 1.9. Steam is heated to 95°C. The slurry is washed with water in a vertical filter press, squeezed at a pressure of 0.6 MPa, and dried with compressed air for 400 seconds. After the compressed air pressure reaches 0.3 MPa, the ammonium polyvanadate generated meets the following mass percentage conditions: V2O5 content 88.5%, Al content 0.005%, Si content 0.02%.

[0034] (3) Drying, calcining and melting; High-purity ammonium metavanadate is flash dried (300°C), calcined in a calcining furnace (inlet 600°C, outlet 400°C), melted in a melting furnace (20Pa, melting zone temperature 780°C, settling zone temperature 280°C), and cast into tablets to produce vanadium pentoxide tablets with a silicon mass percentage of 0.1% and an aluminum mass percentage of 0.25%.

[0035] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for producing low-silicon and low-aluminum vanadium pentoxide tablets, characterized in that: The steps include: (1) Impurity removal of vanadium liquid: The vanadium liquid is heated with steam, and concentrated sulfuric acid and aluminum sulfate are added in sequence to obtain purified vanadium liquid; (2) Sedimentation and filtration: Liquid ammonium sulfate and concentrated sulfuric acid are added to the purified vanadium liquid to adjust the pH, steam-heat it, wash it with water, squeeze it, and dry it with compressed air in a vertical filter press to generate ammonium polyvanadate; (3) Drying, calcining and melting: ammonium polyvanadate is flash dried, calcined in a calcining furnace, melted in a melting furnace and cast into tablets to produce vanadium pentoxide tablets.

2. The method for producing low-silicon and low-aluminum vanadium pentoxide tablets according to claim 1, characterized in that: In the step (1), the V content in the vanadium liquid is 22-28 g / L, the silicon content is 400-500 mg / L, the phosphorus content is 70-120 mg / L, and the temperature of the vanadium liquid after steam heating is 60-75° C. The pH of the purified vanadium liquid after adding concentrated sulfuric acid and aluminum sulfate is 5.5-6.5; The mass fraction of sulfuric acid in concentrated sulfuric acid is 92.5%-93.91%. After adding concentrated sulfuric acid, the pH of the vanadium solution is adjusted to 7.5-8.0; The amount of aluminum sulfate added is 0.14-0.2kg / m 3 Vanadium solution, after adding aluminum sulfate, the pH value of the vanadium solution is adjusted to 5.5-6.

5.

3. The method for producing low-silicon and low-aluminum vanadium pentoxide tablets according to claim 1, characterized in that: In the step (1), in the purified vanadium liquid, the silicon content is ≤100 mg / L, the aluminum content is ≤20 mg / L, the phosphorus content is ≤1 mg / L, and the suspended matter content is ≤50 mg / L.

4. The method for producing low-silicon and low-aluminum vanadium pentoxide tablets according to claim 1, characterized in that: In the step (2), the amount of liquid ammonium sulfate added is 300-400 g / L, the pH is adjusted to 1.9-2.1 with 92.5%-93.91% concentrated sulfuric acid, and steam heated to 95-100° C.; The extrusion pressure is 0.5-0.8MPa; The compressed air drying time is 200-400 seconds, and the compressed air pressure is 0.3-0.5MPa; The generated ammonium polyvanadate meets the following mass percentage conditions: V2O5≥88%, Al≤0.005%, Si≤0.02%.

5. The method for producing low-silicon and low-aluminum vanadium pentoxide tablets according to claim 1, characterized in that: In the step (3), the ammonium polyvanadate is flash dried at a temperature of 250-300°C, the hot air temperature of the calcining furnace is 550-600°C, and the outlet temperature is 390-400°C, thereby obtaining powdered vanadium pentoxide.

6. The method for producing low-silicon and low-aluminum vanadium pentoxide tablets according to claim 1, characterized in that: In the step (3), the powdered vanadium pentoxide is sent to a melting furnace for melting, the temperature of the melting zone of the melting furnace is controlled at 750-800°C, and the mass percentages of silicon and aluminum in the vanadium pentoxide tablets are both ≤0.05%.

7. The method for producing low-silicon and low-aluminum vanadium pentoxide tablets according to claim 1, characterized in that: In step (3), the flash drying is carried out in a flash dryer, all parts of the flash dryer that contact the material are made of 304 and 316L stainless steel, the material of the annular seam is 310S, the wall thickness of the cylinder and the inner cone cylinder is more than 6 mm, and the thickness of the stirring blade is more than 14 mm; All parts of the calcining furnace that come into contact with materials are made of 304 and 316L stainless steel; Flash drying and calcining furnace calcination are both dusted by cyclone dust collectors. The material of the cyclone separator is 304 stainless steel with a wall thickness of not less than 4mm. The cyclone separator uses a bag dust collector to collect dust. The temperature resistance of the filter bag of the bag dust collector is ≥250℃.

8. The method for producing low-silicon and low-aluminum vanadium pentoxide tablets according to claim 1, characterized in that: In the step (3), the bottom of the melting furnace is a water-cooled cast iron bottom, on which a layer of Al2O3≥95% corundum is laid, the molten pool refractory is built with Al2O3≥95% corundum, and the rest is LZ-75 grade high-alumina bricks; The negative pressure in the melting zone of the melting furnace is controlled at -20Pa~-50Pa.

9. The method for producing low-silicon and low-aluminum vanadium pentoxide tablets according to claim 1, characterized in that: In the step (3), the melting furnace is composed of a melting zone, a heat preservation zone, a cooling zone and a settling zone; There are flat arch structures between the melting zone and the insulation zone. The material of the flat arch structure is Al2O3≥95% corundum material. High-alumina bricks are laid on the flat arch structure. The flat arch structure is 500-800mm away from the furnace bottom. The insulation area and the settlement area are separated by masonry walls, which are 800-1000mm away from the furnace top. The wall close to the settlement area is equipped with a steel pipe for cooling air. The temperature in the sedimentation zone is controlled at 250-300°C.

10. The method for producing low-silicon and low-aluminum vanadium pentoxide tablets according to claim 9, characterized in that: In the step (3), a burner is provided on the melting furnace and arranged at the horizontal center of the rear wall. The burner is directly opposite to the flat arch structure. The discharge pipe of the melting furnace is made of 310S material. The discharge point of the melting furnace is 1800-2200mm away from the discharge point.