Acidolysis tank

Abstract

The invention discloses an acidolysis tank, and belongs to the field of chemical equipment. The acidolysis tank comprises a top cover, a side wall and a flat bottom, has the functions of feeding, mixing, acidolysis, exhausting and discharging, can be used for producing mixed acid slurry by decomposing phosphorite with nitric acid, and can be widely applied to the production process of a nitric phosphate fertilizer. The acidolysis tank comprises a top cover, a side wall and a flat bottom, wherein a feeding box and a stirrer are mounted on the top cover of the acidolysis tank; the upper part of the side wall of the acidolysis tank is provided with an overflow port, and the lower part is provided with a discharge port; an acid inlet, a liquid inlet and a feeding hole are formed in the feeding box. The acidolysis tank disclosed by the invention is simple in structure, uniform in acid-ore mixing without clogging, less in ore powder escape, thorough in acidolysis, easy to mount, overhaul, maintain and clean, wide in application range and suitable for nitric acid decomposition phosphorite production systems of various specifications and models.

Description

TECHNICAL FIELD

[0001] The present application relates to an equipment for industrial production, in particular to an acidolysis tank composed of a top cover, a side wall and a flat bottom, which has the functions of feeding, mixing, acidolysis, exhaust and discharging, and can be used for producing mixed acid slurry by decomposing phosphate rock with nitric acid, and can be widely used in the process of nitric phosphate production. BACKGROUND

[0002] In a broad sense, the phosphoric acid produced by decomposing phosphate rock with acid can be collectively referred to as wet-process phosphoric acid, in contrast to thermal-process phosphoric acid (furnace-process phosphoric acid). The acid used must be a strong inorganic acid that can provide sufficient hydrogen ions. In addition to the most commonly used sulfuric acid, hydrochloric acid, fluorosilicic acid and nitric acid can also be used as the medium for decomposing phosphate rock. Compared with other methods, the method of decomposing phosphate rock with sulfuric acid has obvious technical advantages. The product after decomposition is phosphoric acid solution and calcium sulfate, which has extremely low solubility in phosphoric acid, and the separation of the liquid and solid phases can be achieved by simple filtration operation. The process technology of decomposing phosphate rock with sulfuric acid is widely used in domestic wet-process phosphoric acid production. Phosphogypsum is the main by-product of this process technology, and the main component of phosphogypsum is CaSO4·2H2O. About 4-5 tons of phosphogypsum can be produced per ton (100% P2O5) of phosphoric acid. The annual discharge of phosphogypsum in China is close to 68 million tons, and the utilization rate of phosphogypsum is only about 5%. Long-term accumulation of phosphogypsum will pollute surface water and groundwater, and setting up a storage yard requires a large area, high cost and large investment. Phosphogypsum has become one of the largest solid waste discharged in the chemical industry.

[0003] At present, the production capacity of nitric acid in China is about 3.2 million tons, the demand is about 1.6 million tons, and the device operation rate is about 50%. If nitric acid is used as an acidolysis agent to convert P2O5 in phosphate rock into a form that can be absorbed by crops, and the nitric acid itself remains in the solution as a nitrogen fertilizer, a mixed acid slurry containing nitrogen and phosphorus can be obtained, which can be used as raw material to produce nitric phosphate.

[0004] When phosphate rock is decomposed with nitric acid, in order to speed up the reaction rate and improve the conversion rate, the phosphate rock is usually processed into phosphate rock powder. Mixing phosphate rock powder with nitric acid solution will float on the surface of the liquid, and long-time stirring is required to mix the solution uniformly. Part of the phosphate rock powder will escape from the acidolysis tank with the tail gas, which not only blocks the pipeline, but also causes loss. In view of the above problems, it is urgent to provide an equipment for decomposing phosphate rock powder with nitric acid to obtain a mixed acid slurry containing nitrogen and phosphorus. SUMMARY

[0005] The acid tank is a circular tank-shaped closed device composed of a circular top cover, a cylindrical sidewall and a circular flat bottom, has the functions of feeding, mixing, acidolysis, exhaust and discharging, can be used for decomposing phosphate ore by nitric acid to produce mixed acid slurry, and can be widely used in the process of nitric acid phosphate fertilizer production.

[0006] The object of the present application can be achieved by the following technical solutions.

[0007] The acid tank comprises a top cover, a sidewall and a flat bottom, a feeding tank and a stirrer are installed on the top cover of the acid tank, an overflow port is arranged on the upper portion of the sidewall of the acid tank, and a discharging port is arranged on the lower portion of the sidewall of the acid tank.

[0008] In the technical scheme of the present application, a phosphate ore powder feeding pipe is arranged in the feeding port of the feeding tank, the top feeding port of the phosphate ore powder feeding pipe is located above the top surface of the feeding tank, and the lower portion of the phosphate ore powder feeding pipe extends into the acid-ore falling pipe; the top inlet of the acid-ore falling pipe is located above the bottom surface of the feeding tank, and the bottom outlet is located below the liquid level of the acid tank and as close to the paddle as possible.

[0009] In the technical scheme of the present application, the feeding tank is connected with the top cover of the acid tank through a vent pipe.

[0010] In the technical scheme of the present application, a liquid inlet pipe is installed on the acid inlet pipe.

[0011] In the technical scheme of the present application, the overflow port is at an angle of alpha (0°<alpha<90°) with the vertical direction, and the ratio of the height H2 of the inlet M of the overflow port to the height H1 of the sidewall of the acid tank is H2:H1=6-7:10. The height ratio can leave sufficient space for the gas phase above the overflow port, and the liquid effective volume below the overflow port is maximized, and if the height ratio exceeds this value, the paddle should be double-layered, otherwise the reaction is insufficient.

[0012] In the technical scheme of the present application, a plurality of baffles are installed on the sidewall of the acid tank and are uniformly distributed around the center line of the acid tank, the ratio of the height H3 of the baffle to the height H1 of the sidewall of the acid tank is H3:H1=6-7:10, and the ratio of the width W of the baffle to the inner diameter D1 of the acid tank is W:D1=1:13-18. If the height ratio exceeds this value, the mixed acid slurry begins to overflow, and if the height ratio is below this value, the slurry mixing is not good. In addition, if the baffle is too wide, the energy consumption is high, and if the baffle is too narrow, the slurry mixing is not good.

[0013] In the technical scheme of the present application, the ratio of the paddle diameter D2 of the stirrer to the inner diameter D1 of the acidolysis tank is D2:D1=1:3-4, and the ratio of the height H4 of the center line of the paddle from the bottom surface of the acidolysis tank to the paddle diameter D2 is H4:D2=1-3:2. In the technical scheme of the present application, if the paddle diameter is too large, the energy consumption is high, and if the paddle diameter is too small, the slurry mixing is poor. If the height of the paddle from the bottom surface of the acidolysis tank is too high, the bottom surface will be caked; and if the height of the paddle from the bottom surface of the acidolysis tank is too low, the bottom surface will be quickly worn, and the slurry mixing in the upper part of the acidolysis tank is poor.

[0014] In the technical scheme of the present application, an inspection hole is mounted on the top cover, and the inspection hole is provided with a cover plate; the height of the outlet of the discharge port is lower than that of the flat bottom, and the outlet is provided with a cover plate.

[0015] The exhaust port, the inspection hole and the overflow port are all provided with flanges; the overflow port is provided with a cleaning port, and the cleaning port is provided with a cover plate.

[0016] A method for acidolysis by using the acidolysis tank, the method comprising the following steps:

[0017] (1) Raw material nitric acid from a boundary area enters an acid inlet pipe from an acid inlet, washing liquid from a calcium nitrate crystallization separation system enters a liquid inlet pipe from a liquid inlet, the nitric acid and the washing liquid are mixed to enter a feed tank, and the solution in the feed tank overflows to enter an acid ore falling pipe;

[0018] (2) Phosphorite powder from the boundary area enters a phosphorite powder feed pipe, and the phosphorite powder discharged from the bottom outlet directly enters the acid ore falling pipe; the nitric acid solution in the acid ore falling pipe directly washes the phosphorite powder out of the bottom outlet to enter the acidolysis tank, the nitric acid solution and the phosphorite powder are preliminarily mixed, and the nitric acid in the nitric acid solution and the phosphorite powder are preliminarily acidolysed; the stirrer in the acidolysis tank mixes the nitric acid solution and the phosphorite powder again, the nitric acid in the nitric acid solution and the phosphorite powder continue to react, the reaction temperature is 60-80℃, the solution residence time is 40-60 minutes, the target product mixed acid slurry of the reaction completion is discharged from the acidolysis tank to the boundary area from the overflow port, and tail gas escaped in the reaction process is discharged from the acidolysis tank to the boundary area from the exhaust port.

[0019] In the method, the washing liquid of the calcium nitrate crystallization separation system contains P2O5 with a mass concentration of 3-8%, Ca 2+ with a mass concentration of 1-5%, and NO3 - with a mass concentration of 40-50%;

[0020] The raw material nitric acid contains HNO3 with a mass concentration of 50-60%;

[0021] The phosphorite powder contains P2O5 with a mass concentration of 25-35%, and Ca 2+ with a mass concentration of 25-35%;

[0022] The mixed acid slurry contains P2O5 with a mass concentration of 5-15%, and Ca 2+5-15% by mass, containing NO3 - 30-40% by mass.

[0023] In some specific technical solutions, an acidolysis tank has the functions of feeding, mixing, acidolysis, exhaust, and discharging, and can be used for producing mixed acid slurry by decomposing phosphate rock with nitric acid, and can be widely used in the process of producing nitric acid phosphate fertilizer. Nitric acid from a boundary zone enters an acid inlet pipe from an acid inlet A, and washing liquid enters a liquid inlet pipe from a liquid inlet B. After mixing, the two liquids enter a feed tank from a liquid outlet C. The solution in the feed tank overflows from a top inlet G and enters an acid ore falling pipe. Phosphate rock powder from the boundary zone enters a phosphate rock powder feed pipe from a feed inlet E. The phosphate rock powder discharged from a bottom outlet F directly enters the acid ore falling pipe. The solution in the acid ore falling pipe directly flows into the acidolysis tank from a bottom outlet J. The solution and the phosphate rock powder are preliminarily mixed, and the nitric acid in the solution and the phosphate rock powder are preliminarily acidolysed. The agitator mixes the solution and the phosphate rock powder in the acidolysis tank again, the nitric acid in the solution and the phosphate rock powder continue to react, and the mixed acid slurry after reaction is discharged from the acidolysis tank to the boundary zone. The acid and the phosphate rock powder that can be acidolysed are not only one kind, and the nitric acid and the phosphate rock powder are taken as an example:

[0024] In some more specific technical solutions, an acidolysis tank is a closed circular tank composed of a circular top cover, a cylindrical side wall, and a circular flat bottom.

[0025] The beneficial effects of the present application are as follows:

[0026] The present application provides an acidolysis tank, which can be widely used in the process of producing nitric acid phosphate fertilizer.

[0027] The acid inlet pipe is provided with a liquid inlet pipe. The washing liquid is mixed with the nitric acid and then enters the feed tank. The concentration of the nitric acid solution is uniform, which is beneficial to the subsequent acidolysis reaction. The nitric acid solution enters the feed tank from the bottom of the side wall of the feed tank, and the bottom of the feed tank is not easy to be caked. The nitric acid solution overflows from the top inlet and enters the acid ore falling pipe, the flow is stable, the surface of the acid ore falling pipe is not easy to be caked, dust is reduced, and the mixed slurry directly enters the inside of the acidolysis tank after being mixed with the continuously added phosphate rock powder, and the acid ore falling pipe is discharged from the place close to the slurry blade. The nitric acid and the phosphate rock powder are rapidly and uniformly mixed in the acidolysis tank.

[0028] The outer diameter of the phosphate rock powder feed pipe is smaller than the inner diameter of the acid ore falling pipe. The bottom outlet of the phosphate rock powder feed pipe is located in the top inlet of the acid ore falling pipe. The phosphate rock powder discharged from the phosphate rock powder feed pipe directly enters the acid ore falling pipe, and the phosphate rock powder and the nitric acid solution are rapidly and completely mixed in the acid ore falling pipe, and the escape of the phosphate rock powder is reduced.

[0029] The outlet of the air pipe is connected with the top of the acidolysis tank, and the pollution points are reduced.

[0030] A large power (1.7-2.2 kW / m 3With its effective volume and powerful single-layer turbine agitator, acid and minerals are mixed evenly and rapidly.

[0031] The overflow outlet has a cleaning port and the overflow outlet forms an angle α with the vertical direction, where α < 90°, so that the slurry overflows smoothly and is not easily blocked;

[0032] Several baffles are installed on the side wall of the acid hydrolysis tank and are evenly distributed around the center line of the acid hydrolysis tank to ensure that the slurry is fully and thoroughly mixed.

[0033] The lowest point R at the discharge port is lower than the lowest point P at the inlet, so the slurry can be completely discharged during cleaning. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of the present invention.

[0035] The components include: acid leaching tank 1, baffle 2, acid ore dropper 3, acid inlet pipe 4, liquid inlet pipe 5, feed box 6, phosphate rock powder feed pipe 7, vent pipe 8, agitator 9, paddle blade 10, exhaust port 11, inspection port 12, cleaning port 13, overflow port 14, and discharge port 15. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The acid-hydrolyzable substances are not limited to phosphate rock powder and nitric acid. Phosphate rock powder and nitric acid are used as examples:

[0038] like Figure 1The acidolysis tank 1 is a circular tank-shaped closed device composed of a circular top cover, a cylindrical sidewall and a circular flat bottom, with an inner diameter D1 = 4700 mm, a sidewall height H1 = 4700 mm, a feed tank 6 and a stirrer 9 mounted on the top cover of the acidolysis tank 1; an overflow port 14 is arranged on the upper portion of the sidewall of the acidolysis tank 1, and a discharge port 15 is arranged on the lower portion of the sidewall of the acidolysis tank 1; the feed tank 6 is provided with an acid inlet, a liquid inlet and a feed inlet.

[0039] A phosphate rock powder feeding pipe 7 is arranged in the feed inlet of the feed tank 6, the top feed inlet of the phosphate rock powder feeding pipe 7 is located above the top surface of the feed tank 6, and the lower portion of the phosphate rock powder feeding pipe 7 extends into the acid-rock falling pipe 3; the top inlet of the acid-rock falling pipe 3 is located above the bottom surface of the feed tank 6, and the bottom outlet is located below the liquid level of the acidolysis tank 1 and is arranged as close to the paddle 10 as possible.

[0040] The feed tank 6 is connected to the top cover of the acidolysis tank 1 through a vent pipe 8.

[0041] The acid inlet pipe 4 is provided with a liquid inlet pipe 5.

[0042] The overflow port 14 is 75° to the vertical direction, and the height H2 = 3140 mm of the inlet M of the overflow port 14;

[0043] Four baffles 2 are mounted on the sidewall of the acidolysis tank 1 and are uniformly distributed around the center line of the acidolysis tank 1, the height H3 = 2950 mm of the baffle 2, and the width W = 300 mm of the baffle 2;

[0044] The installed power of the stirrer 9 is 100 kW, the diameter D2 = 1350 mm of the paddle 10, the rotating speed is 77.6 r / min, the end point linear velocity is 5.49 m / s, the blade has six pieces, and the rear bending of the blade is provided with only one layer, and the center line distance H4 = 1100 mm of the paddle 10 from the bottom surface of the acidolysis tank 1;

[0045] An inspection port 12 is mounted on the top cover, and the inspection port 12 is provided with a cover plate; the height of the outlet of the discharge port 15 is lower than that of the flat bottom, and the outlet is provided with a cover plate;

[0046] The exhaust port 11, the inspection port 12 and the overflow port 14 are all provided with flanges; the overflow port 14 is provided with a cleaning port 13, and the cleaning port 13 is provided with a cover plate.

[0047] A method for decomposing phosphate rock by nitric acid by using the acidolysis tank, the method comprising the following contents:

[0048] The raw material, nitric acid (containing HNO3 with a mass concentration of 58%), from the boundary area enters the acid inlet pipe 4 from the acid inlet A, the washing liquid (containing P2O5 with a mass concentration of 5.466%, containing Ca 2+ with a mass concentration of 3.563%, containing NO3 -The nitric acid solution with P2O5 mass concentration of 43.188% from inlet B enters the inlet pipe 5, and the nitric acid solution mixes with the washing liquid and then goes out from outlet C into the feed tank 6. The solution in the feed tank 6 overflows from the top inlet G into the acid ore falling pipe 3. The raw material, phosphate rock powder (containing P2O5 mass concentration of 31.54%, containing Ca 2+ The phosphate rock powder with P2O5 mass concentration of 32.029% from the inlet E enters the phosphate rock powder feeding pipe 7, and the phosphate rock powder directly goes out from the bottom outlet F into the acid ore falling pipe 3. The nitric acid solution in the acid ore falling pipe 3 directly flows into the acidolysis tank 1 from the bottom outlet J, and the nitric acid solution and the phosphate rock powder are preliminarily mixed and the nitric acid in the nitric acid solution and the phosphate rock powder are preliminarily acidolysed. The agitator 9 in the acidolysis tank 1 mixes the nitric acid solution and the phosphate rock powder again, and the nitric acid in the nitric acid solution and the phosphate rock powder continue to react. The reaction temperature is 70°C, the solution residence time is 60 minutes, and the target product, the mixed acid slurry (containing P2O5 mass concentration of 9.836%, containing Ca 2+ The nitric acid solution with P2O5 mass concentration of 43.188% from inlet B enters the inlet pipe 5, and the nitric acid solution mixes with the washing liquid and then goes out from outlet C into the feed tank 6. The solution in the feed tank 6 overflows from the top inlet G into the acid ore falling pipe 3. The raw material, phosphate rock powder (containing P2O5 mass concentration of 31.54%, containing Ca - The nitric acid solution with P2O5 mass concentration of 43.188% from inlet B enters the inlet pipe 5, and the nitric acid solution mixes with the washing liquid and then goes out from outlet C into the feed tank 6. The solution in the feed tank 6 overflows from the top inlet G into the acid ore falling pipe 3. The raw material, phosphate rock powder (containing P2O5 mass concentration of 31.54%, containing Ca

[0049] The operation results of the present application are shown in Table 1

[0050] The performance test results of the acidolysis tank for a 50-ton / hour nitric acid phosphate fertilizer device

[0051]

[0052]

Claims

1. An acid hydrolysis tank characterized by: The acidolysis tank (1) comprises a top cover, a side wall and a flat bottom, the top cover is provided with a feeding tank (6) and a stirrer (9), the upper part of the side wall is provided with an overflow port (14), and the lower part of the side wall is provided with a discharge port (15); the feeding tank (6) is provided with an acid inlet, a liquid inlet and a feeding port.

2. The acid hydrolysis tank of claim 1, wherein: The feeding port of the feeding tank (6) is provided with a phosphate ore powder feeding pipe (7), the top feeding port of the phosphate ore powder feeding pipe (7) is located above the top surface of the feeding tank (6), and the lower part of the phosphate ore powder feeding pipe (7) extends into the acid ore falling pipe (3); the top inlet of the acid ore falling pipe (3) is located above the bottom surface of the feeding tank (6), and the bottom outlet is located below the liquid level of the acidolysis tank (1) and is arranged as close to the paddle (10) as possible.

3. The acid hydrolysis tank of claim 1, wherein: The feeding tank (6) is connected with the top cover of the acidolysis tank (1) through a vent pipe (8).

4. The acid hydrolysis tank of claim 1, wherein: The acid inlet pipe (4) is provided with a liquid inlet pipe (5).

5. The acid hydrolysis tank of claim 1, wherein: The overflow port (14) is at an angle α (0°<α<90°) with the vertical direction, and the ratio of the height H2 of the inlet M of the overflow port (14) to the height H1 of the side wall of the acidolysis tank (1) is H2:H1=6-7:

10.

6. The acid hydrolysis tank of claim 1, wherein: A plurality of baffles (2) are arranged on the side wall of the acidolysis tank (1) and are uniformly distributed around the center line of the acidolysis tank (1), the ratio of the height H3 of the baffle (2) to the height H1 of the side wall of the acidolysis tank (1) is H3:H1=6-7:10, and the ratio of the width W of the baffle (2) to the inner diameter D1 of the acidolysis tank (1) is W:D1=1:13-18.

7. The acid hydrolysis tank of claim 1, wherein: The ratio of the diameter D2 of the paddle (10) of the stirrer (9) to the inner diameter D1 of the acidolysis tank (1) is D2:D1=1:3-4, and the ratio of the height H4 of the center line of the paddle (10) from the bottom surface of the acidolysis tank (1) to the diameter D2 of the paddle (10) is H4:D2=1-3:

2.

8. The acid hydrolysis tank of claim 1, wherein: An inspection port (12) is arranged on the top cover, and the inspection port (12) is provided with a cover plate; the height of the outlet of the discharge port (15) is lower than that of the flat bottom, and the outlet is provided with a cover plate; The exhaust port (11), the inspection port (12) and the overflow port (14) are all provided with flanges; the overflow port (14) is provided with a cleaning port (13), and the cleaning port (13) is provided with a cover plate.

9. A method for acidolysis using the acidolysis tank according to claim 1, characterized by, The method comprises the following steps: (1) The raw material nitric acid from the boundary area enters the acid inlet pipe from the acid inlet, the washing liquid from the calcium nitrate crystallization separation system enters the liquid inlet pipe from the liquid inlet, the nitric acid and the washing liquid are mixed and then enter the feeding tank (6), and the solution in the feeding tank (6) overflows into the acid ore falling pipe (3); (2) The phosphate ore powder from the boundary area enters the phosphate ore powder feeding pipe (7), the phosphate ore powder from the bottom outlet directly enters the acid ore falling pipe (3), the nitric acid solution in the acid ore falling pipe (3) directly flows out of the bottom outlet and enters the acidolysis tank (1), the nitric acid solution and the phosphate ore powder are preliminarily mixed, the nitric acid in the nitric acid solution and the phosphate ore powder are preliminarily acidolysed, the stirrer in the acidolysis tank (1) mixes the nitric acid solution and the phosphate ore powder again, the nitric acid in the nitric acid solution and the phosphate ore powder continue to react, the reaction temperature is 60-80℃, the solution residence time is 40-60 minutes, the target product mixed acid slurry is discharged from the acidolysis tank (1) through the overflow port (14) to the boundary area, and the tail gas escaped in the reaction process is discharged from the exhaust port (11) of the acidolysis tank (1) to the boundary area.

10. The method of claim 9, wherein, The washing liquid of the calcium nitrate crystallization separation system contains P2O5 mass concentration of 3-8%, Ca 2+ mass concentration of 1-5%, and NO3 - mass concentration of 40-50%; Raw material nitric acid: HNO3 mass concentration 50-60%; Phosphorite powder: P2O5 mass concentration 25-35%, Ca 2+ 25-35%; Mixed acid slurry: P2O5 mass concentration 5-15%, Ca 2+ NO3 mass concentration 5-15% - mass concentration 30-40%.

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