A system for producing mixed acid solution by decomposing phosphate ore with nitric acid

Abstract

The utility model discloses a system for producing mixed acid solution by decomposing phosphate ore with nitric acid, belonging to the field of chemical industry. The system comprises a phosphate ore powder hopper, a phosphate ore powder metering scale, a urea hopper, a urea metering scale, a feeding acidolysis tank, an acidolysis tank stirrer, an acidolysis buffer tank, a buffer tank stirrer, a sedimentation tank, a sedimentation tank rake, a mixed acid storage tank, a mixed acid pump, a filter, and an acid-insoluble matter conveyor. The above system and method are used to produce mixed acid solution by decomposing phosphate ore with nitric acid. The mixed acid solution can be used as raw material to produce nitric acid phosphate fertilizer. When nitric acid is used to decompose phosphate ore, the nitric acid serves as an acidolysis agent to convert P2O5 in the ore into a form that can be absorbed by crops. Moreover, the nitric acid itself remains in the product as a nitrogen fertilizer, playing a role of "carrying phosphorus with nitrogen". The reaction of decomposing phosphate ore with nitric acid is rapid and efficient, does not produce phosphogypsum, and has no problem of phosphogypsum storage, thus protecting the environment.

Description

Technical Field

[0001] This utility model relates to the field of chemical production technology, specifically to a system for producing mixed acid solution by decomposing phosphate rock with nitric acid. Background Technology

[0002] Broadly speaking, compared to thermal phosphoric acid (furnace phosphoric acid), any phosphoric acid produced by acid decomposition of phosphate rock can be collectively referred to as wet-process phosphoric acid. The acid used must be a strong inorganic acid that can provide sufficient hydrogen ions. Besides the most commonly used sulfuric acid, hydrochloric acid, fluorosilicic acid, and nitric acid can also be used as media for decomposing phosphate rock. The sulfuric acid decomposition method for producing phosphoric acid from phosphate rock has significant technological advantages compared to other methods. The decomposition products are phosphoric acid solution and calcium sulfate, the latter being a solid with very low solubility in phosphoric acid. The separation of the liquid and solid phases can be achieved through simple filtration. In China, the commonly used wet-process phosphoric acid technology is sulfuric acid decomposition of phosphate rock. Phosphogypsum is the main byproduct of this technology. The main components of phosphogypsum are CaSO4 and 2H2O. Approximately 4-5 tons of phosphogypsum are produced for every ton of phosphoric acid produced (based on 100% P2O5). China's annual phosphogypsum emissions are close to 68 million tons, while the utilization rate of phosphogypsum is only about 5%. Because long-term accumulation of phosphogypsum will cause pollution of surface water and groundwater, and setting up stockpiles requires a lot of land, high costs and large investments, phosphogypsum has become one of the largest solid wastes emitted by the chemical industry.

[0003] Currently, China's nitric acid production capacity is approximately 3.2 million tons, while demand is about 1.6 million tons. The operating rate of these plants is about 50%. If nitric acid could be used as an acidolytic agent to convert the P2O5 in phosphate rock into a form that can be absorbed by crops, while the nitric acid itself remains in the solution as nitrogen fertilizer, a mixed acid solution containing nitrogen and phosphorus could be obtained. This mixed acid solution could then be used as a raw material to produce nitric acid phosphate fertilizer. Therefore, there is an urgent need to provide a system and method for producing mixed acid solution by decomposing phosphate rock with nitric acid. This would not only increase the operating rate of nitric acid plants and revitalize idle assets, but also produce nitric acid phosphate fertilizer without generating phosphogypsum, eliminating the problem of phosphogypsum stockpiling, and protecting the environment. Utility Model Content

[0004] The purpose of this invention is to provide a system for producing a mixed acid solution by decomposing phosphate rock with nitric acid. This mixed acid solution can be used as a raw material to produce nitric acid phosphate fertilizer. During the decomposition of phosphate rock, nitric acid acts as an acid hydrolysant, converting the P2O5 in the ore into a form that can be absorbed by crops; moreover, it itself remains in the product as a nitrogen fertilizer, achieving a "nitrogen-driven phosphorus" effect. The decomposition of phosphate rock with nitric acid is rapid and efficient, does not produce phosphogypsum, avoids the problem of phosphogypsum stockpiling, and protects the environment.

[0005] The objective of this patent can be achieved through the following technical solutions:

[0006] A system for producing a mixed acid solution by decomposing phosphate rock with nitric acid includes a buffer tank, a stirrer, and a settling tank. Nitric acid pipelines from the boundary area, washing liquid pipelines from a calcium nitrate crystallization separation system, phosphate rock powder conveying pipelines from the boundary area, and urea conveying pipelines from the boundary area are respectively connected to the top of a feeding acidolysis tank. The feeding acidolysis tank is sequentially connected to the settling tank via an acidolysis buffer tank. The bottom of the settling tank is connected to a filter and an acid-insoluble matter conveyor.

[0007] The top of the settling tank is connected to the mixed acid storage tank.

[0008] In the above system: phosphate rock powder from the boundary area is connected to the top of the acid hydrolysis tank via a phosphate rock powder storage hopper and a phosphate rock powder metering scale.

[0009] In the above system: urea from the boundary area is connected to the top of the feeding acid hydrolysis tank in sequence through the urea storage hopper, the urea metering scale, and the feed acid hydrolysis tank.

[0010] In the above system, both the feeding acid hydrolysis tank and the acid hydrolysis buffer tank are equipped with a stirrer.

[0011] In the above system, a settling tank rake is installed in the settling tank.

[0012] In the above system: the liquid output of the filter is connected to the mixed acid storage tank.

[0013] In some more specific technical solutions, a system for producing mixed acid solution by decomposing phosphate rock with nitric acid includes a phosphate rock powder storage hopper, a phosphate rock powder weighing scale, a urea storage hopper, a urea weighing scale, a feeding acidolysis tank, an acidolysis tank agitator, an acidolysis buffer tank, a buffer tank agitator, a settling tank, a settling tank rake, a mixed acid storage tank, a mixed acid pump, a filter, and an acid-insoluble matter conveyor. The nitric acid pipeline from the boundary area is connected to the top inlet A3 of the feeding acidolysis tank, and this pipeline is equipped with a washing liquid pipeline from a calcium nitrate crystallization separation system. The phosphate rock powder conveying equipment from the boundary area is connected to the top inlet A1 of the phosphate rock powder storage hopper. The bottom outlet B1 of the phosphate rock powder storage hopper is connected to the top inlet B3 of the feeding acid hydrolysis tank via a phosphate rock powder metering scale. The urea conveying equipment from the boundary area is connected to the top inlet A2 of the urea storage hopper. The bottom outlet B2 of the urea storage hopper is connected to the top inlet C3 of the feeding acid hydrolysis tank via a urea metering scale. The overflow outlet E3 of the feeding acid hydrolysis tank is connected to the side inlet A4 of the acid hydrolysis buffer tank. The overflow outlet C4 of the acid hydrolysis buffer tank is connected to the side inlet A5 of the settling tank. The overflow outlet B5 of the settling tank is connected to the top inlet B6 of the mixed acid storage tank. The side outlet C6 of the mixed acid storage tank is connected to the mixed acid solution pipeline to the boundary area via a mixed acid pump.

[0014] In the above system: the top outlet D3 of the feeding acid hydrolysis tank and the top outlet B4 of the acid hydrolysis buffer tank are connected to the tail gas pipeline of the boundary zone; the bottom outlet C5 of the settling tank is connected to the slurry inlet of the filter; the process water inlet of the filter is connected to the process water pipeline from the boundary zone; the liquid outlet of the filter is connected to the top inlet A6 of the mixed acid storage tank; the solid outlet of the filter is connected to the inlet of the acid insoluble material conveyor; and the outlet of the acid insoluble material conveyor is connected to the boundary zone.

[0015] In the above system: the feeding acid hydrolysis tank is equipped with an acid hydrolysis tank agitator, the acid hydrolysis buffer tank is equipped with a buffer tank agitator, and the settling tank is equipped with a settling tank rake.

[0016] A method for producing a mixed acid solution by decomposing phosphate rock with nitric acid using the above-described system, the method comprising the following steps:

[0017] (1) Raw material and auxiliary material feeding: The raw material from the boundary area - nitric acid (containing HNO3 mass concentration ≤68%) is mixed with the washing liquid from the calcium nitrate crystallization separation system and enters the feeding acid hydrolysis tank through the top inlet A3; the raw material from the boundary area - phosphate rock powder enters the phosphate rock powder storage hopper through the top inlet A1, and the phosphate rock powder in the storage hopper exits the phosphate rock powder storage hopper through the bottom outlet B1. After being measured by the phosphate rock powder metering scale, it enters the feeding acid hydrolysis tank through the top inlet B3; the auxiliary material from the boundary area - urea (containing N mass concentration ≤46%) enters the urea storage hopper through the top inlet A2, and the urea in the storage hopper exits the urea storage hopper through the bottom outlet B2. After being measured by the urea metering scale, it enters the feeding acid hydrolysis tank through the top inlet C3; the molar ratio of N to Ga added to the feeding acid hydrolysis tank is ≤3:1, and the mass ratio of urea to phosphate rock powder is ≤1:100;

[0018] (2) Nitric acid decomposition of phosphate rock: In the feeding acid hydrolysis tank, nitric acid reacts with phosphate rock powder under the stirring of the acid hydrolysis tank agitator to produce phosphoric acid and calcium nitrate, and urea reacts with nitrous acid to produce nitrogen gas. The reaction temperature of the feeding acid hydrolysis tank is ≤80℃ and the solution residence time is ≤40 minutes. The slurry ① that has reached the residence time exits the feeding acid hydrolysis tank from the overflow outlet E3 and enters the acid hydrolysis buffer tank through the side inlet A4. Under the stirring of the buffer tank agitator, the slurry ① continues to react. The reaction temperature of the acid hydrolysis buffer tank is ≤80℃ and the solution residence time is ≤40 minutes. The slurry ② that has reached the residence time exits the acid hydrolysis buffer tank from the overflow outlet C4 and enters the settling tank through the side inlet A5. The tail gas that escapes during the reaction is mainly nitrogen gas and water vapor, which go to the boundary area from the top outlet D3 of the feeding acid hydrolysis tank and the top outlet B4 of the acid hydrolysis buffer tank.

[0019] (3) Removal of impurities by mixed acid: In the settling tank, the clear liquid exits from the overflow outlet B5 and enters the mixed acid storage tank through the top inlet B6. The thick slurry exits from the bottom outlet C5 and enters the filter through the slurry feed end. In the filter, the solids and clear liquid are separated, and the separated solids are washed and separated with process water from the boundary area. The separated clear liquid and washing liquid exit from the liquid outlet end of the filter and enter the mixed acid storage tank through the top inlet A6. The separated solids exit from the solids outlet end of the filter and are sent to the boundary area as acid insoluble matter via the acid insoluble matter conveyor. The solution in the mixed acid storage tank exits from the side outlet C6 and is sent to the calcium nitrate crystallization separation system via the mixed acid pump as the target product - mixed acid solution.

[0020] A method for producing a mixed acid solution by decomposing phosphate rock with nitric acid includes mixing and feeding nitric acid with washing liquid, metering and feeding phosphate rock powder and urea, reacting nitric acid with phosphate rock powder and urea with nitrous acid, clarifying and separating the reacted slurry, filtering and washing acid-insoluble substances, and discharging the mixed acid solution. The method is characterized by the following steps: feeding raw materials and auxiliary materials, decomposing phosphate rock with nitric acid, and removing impurities with mixed acid.

[0021] (1) Raw material and auxiliary material feeding: The raw material from the boundary area - nitric acid (containing HNO3 mass concentration of 50%~68%) is mixed with the washing liquid from the calcium nitrate crystallization separation system and enters the feeding acid lysis tank through the top inlet A3; the raw material from the boundary area - phosphate rock powder enters the phosphate rock powder storage hopper through the top inlet A1, and the phosphate rock powder in the storage hopper exits the phosphate rock powder storage hopper through the bottom outlet B1. After being measured by the phosphate rock powder metering scale, it enters the feeding acid lysis tank through the top inlet B3; the auxiliary material from the boundary area - urea (containing N mass concentration of 46%) enters the urea storage hopper through the top inlet A2, and the urea in the storage hopper exits the urea storage hopper through the bottom outlet B2. After being measured by the urea metering scale, it enters the feeding acid lysis tank through the top inlet C3; the molar ratio of N to Ga in the feeding acid lysis tank is 2~3:1, and the mass ratio of urea to phosphate rock powder is 1~10:1000;

[0022] (2) Nitric acid decomposition of phosphate rock: In the acid hydrolysis tank, nitric acid reacts with phosphate rock powder under the stirring of the acid hydrolysis tank agitator to produce phosphoric acid and calcium nitrate, and urea reacts with nitrous acid to produce nitrogen gas. The reaction temperature of the acid hydrolysis tank is 50℃~80℃, and the solution residence time is 10~40 minutes. The slurry ① that has reached the residence time exits the acid hydrolysis tank from the overflow outlet E3 and enters the acid hydrolysis buffer tank through the side inlet A4. Under the stirring of the buffer tank agitator, the slurry ① continues to react. The reaction temperature of the acid hydrolysis buffer tank is 50℃~80℃, and the solution residence time is 10~40 minutes. The slurry ② that has reached the residence time exits the acid hydrolysis buffer tank from the overflow outlet C4 and enters the settling tank through the side inlet A5. The tail gas that escapes during the reaction is mainly nitrogen gas and water vapor, which goes to the boundary area from the top outlet D3 of the acid hydrolysis tank and the top outlet B4 of the acid hydrolysis buffer tank.

[0023] (3) Removal of impurities by mixed acid: In the settling tank, the clear liquid exits from the overflow outlet B5 and enters the mixed acid storage tank through the top inlet B6. The thick slurry exits from the bottom outlet C5 and enters the filter through the slurry feed end. In the filter, the solids and clear liquid are separated, and the separated solids are washed and separated with process water from the boundary area. The separated clear liquid and washing liquid exit from the liquid outlet end of the filter and enter the mixed acid storage tank through the top inlet A6. The separated solids exit from the solids outlet end of the filter and are sent to the boundary area as acid insoluble matter via the acid insoluble matter conveyor. The solution in the mixed acid storage tank exits from the side outlet C6 and is sent to the calcium nitrate crystallization separation system via the mixed acid pump as the target product - mixed acid solution.

[0024] The beneficial effects of this invention are:

[0025] The reaction time for decomposing phosphate rock with nitric acid is 20-60 minutes, which is significantly shorter than that of decomposing phosphate rock with sulfuric acid (120-360 minutes). During the decomposition of phosphate rock with nitric acid, the nitric acid acts as an acidolytic agent, converting the P2O5 in the ore into a form that can be absorbed by crops. Furthermore, it also remains in the product as a nitrogen fertilizer, playing a role in "carrying phosphorus with nitrogen." The decomposition of phosphate rock with nitric acid does not produce phosphogypsum. Compared to the sulfuric acid process, producing 1 ton of P2O5 results in approximately 5 tons less phosphogypsum emissions, eliminating the problem of phosphogypsum stockpiling, protecting the environment, and introducing approximately 0.66-1 ton of nitrate nitrogen.

[0026] The mixed acid solution of this patent can be used to prepare nitrate phosphate fertilizer (containing both ammonium nitrate and ammonium phosphate); nitrate phosphate fertilizer contains both readily available nitrate nitrogen (NO3) and readily available nitrate nitrogen (NO3). - It contains water-soluble P2O5, as well as ammonium nitrogen (NH4) which has a longer-lasting fertilizer effect. + Nitrogen phosphate fertilizer is suitable for dryland crops, especially crops such as tobacco and citrus that require nitrate nitrogen supply, to improve the quality of cash crops. It also has significant fertilizer effects on grain crops such as wheat, corn and rice, and cash crops such as rapeseed, tea, cotton and soybeans, especially in medium and low fertility soils.

[0027] Phosphate rock typically contains small amounts of reducing agents, such as sulfides and organic matter, which will reduce some nitric acid to nitrous acid;

[0028] 4HNO3 + 2C == 4HNO2 + 2CO2

[0029] 2HNO3 + S == 2HNO2 + SO2

[0030] Nitrous acid decomposes into nitrogen oxides, which are a serious pollutant to the environment.

[0031] 2HNO2 == NO + NO2 + H2O

[0032] Adding an appropriate amount of urea (NH2CONH2) can eliminate nitrogen oxide pollution;

[0033] NH2CONH2 + 2HNO2 == 2N2 + CO2 + 3H2O

[0034] Therefore, a small amount of urea is added to the acid hydrolysis tank to prevent pollution and protect the environment.

[0035] The main component of acid-insoluble matter in acid hydrolysis slurry is SiO2. To prevent acid-insoluble matter from eroding and scaling downstream equipment, pipelines and valves, the acid-insoluble matter is settled, filtered and washed with process water to recover the effective components in the acid-insoluble matter. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the process flow in this utility model.

[0037] Among them, 1 is a phosphate rock powder storage hopper, 2 is a phosphate rock powder weighing scale, 3 is a urea storage hopper, 4 is a urea weighing scale, 5 is a feeding acid hydrolysis tank, 6 is an acid hydrolysis tank agitator, 7 is an acid hydrolysis buffer tank, 8 is a buffer tank agitator, 9 is a settling tank, 10 is a settling tank rake, 11 is a mixed acid storage tank, 12 is a mixed acid pump, 13 is a filter, and 14 is an acid insoluble matter conveyor. Detailed Implementation

[0038] The technical solutions of the embodiments of this patent will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this patent, not all of them. The components of the embodiments of this patent 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 this patent provided in the accompanying drawings is not intended to limit the scope of the claimed patent, but merely to represent selected embodiments of this patent. All other embodiments obtained by those skilled in the art based on the embodiments of this patent without inventive effort are within the scope of protection of this patent. The embodiments of this patent 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 this patent, and should not be construed as limiting this patent.

[0039] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0040] like Figure 1A system for producing a mixed acid solution by decomposing phosphate rock with nitric acid is characterized in that: the system includes a phosphate rock powder storage hopper 1, a phosphate rock powder weighing scale 2, a urea storage hopper 3, a urea weighing scale 4, a feeding acidolysis tank 5, an acidolysis tank agitator 6, an acidolysis buffer tank 7, a buffer tank agitator 8, a settling tank 9, a settling tank rake 10, a mixed acid storage tank 11, a mixed acid pump 12, a filter 13, and an acid-insoluble matter conveyor 14; the nitric acid pipeline from the boundary area is connected to the top inlet A3 of the feeding acidolysis tank 5, and this pipeline is equipped with a washing liquid pipeline from a calcium nitrate crystallization separation system; the phosphate rock powder conveying equipment from the boundary area is connected to the top inlet A1 of the phosphate rock powder storage hopper 1. The bottom outlet B1 of the phosphate rock powder storage hopper 1 is connected to the top inlet B3 of the feeding acid hydrolysis tank 5 via the phosphate rock powder metering scale 2. The urea conveying equipment from the boundary area is connected to the top inlet A2 of the urea storage hopper 3. The bottom outlet B2 of the urea storage hopper 3 is connected to the top inlet C3 of the feeding acid hydrolysis tank 5 via the urea metering scale 4. The overflow outlet E3 of the feeding acid hydrolysis tank 5 is connected to the side inlet A4 of the acid hydrolysis buffer tank 7. The overflow outlet C4 of the acid hydrolysis buffer tank 7 is connected to the side inlet A5 of the settling tank 9. The overflow outlet B5 of the settling tank 9 is connected to the top inlet B6 of the mixed acid storage tank 11. The side outlet C6 of the mixed acid storage tank 11 is connected to the mixed acid solution pipeline to the boundary area via the mixed acid pump 12.

[0041] The top outlet D3 of the acid hydrolysis tank 5 and the top outlet B4 of the acid hydrolysis buffer tank 7 are connected to the tail gas pipeline of the boundary area; the bottom outlet C5 of the settling tank 9 is connected to the slurry feed end of the filter 13; the process water feed end of the filter 13 is connected to the process water pipeline from the boundary area; the liquid discharge end of the filter 13 is connected to the top inlet A6 of the mixed acid storage tank 11; and the solid discharge end of the filter 13 is connected to the feed end of the acid insoluble conveyor 14. The discharge end of the acid insoluble conveyor 14 is connected to the boundary area.

[0042] The feeding acid hydrolysis tank 5 is equipped with an acid hydrolysis tank agitator 6, the acid hydrolysis buffer tank 7 is equipped with a buffer tank agitator 8, and the settling tank 9 is equipped with a settling tank rake 10.

[0043] The method for producing mixed acid solution by decomposing phosphate rock with nitric acid using the above system includes the following steps:

[0044] (1) Raw material and auxiliary material feed: Raw material from the boundary area—nitric acid (containing 58% HNO3 by mass) and washing liquid from the calcium nitrate crystallization separation system (containing 5.466% P2O5 by mass, containing Ca) 2+ Mass concentration 3.563%, containing NO3. - The mixture (43.188% by mass) is fed into the acid leaching tank 5 through the top inlet A3; the raw material from the boundary area is phosphate rock powder (containing 31.54% P2O5 by mass and Ca). 2+Phosphate rock powder (32.029% mass concentration) enters phosphate rock powder storage hopper 1 through top inlet A1. The phosphate rock powder in the hopper exits phosphate rock powder storage hopper 1 through bottom outlet B1, is measured by phosphate rock powder weighing scale 2, and then enters feeding acid hydrolysis tank 5 through top inlet B3. Auxiliary material from the boundary area—urea (containing N mass concentration of 46%)—enters urea storage hopper 3 through top inlet A2. The urea in the hopper exits urea storage hopper 3 through bottom outlet B2, is measured by urea weighing scale 4, and then enters feeding acid hydrolysis tank 5 through top inlet C3. The molar ratio of N to Ga added to feeding acid hydrolysis tank 5 is 253:100, and the mass ratio of urea to phosphate rock powder is 6:1000.

[0045] (2) Nitric acid decomposition of phosphate rock: In the acid hydrolysis tank 5, under the stirring of the acid hydrolysis tank agitator 6, nitric acid reacts with phosphate rock powder to produce phosphoric acid and calcium nitrate, and urea reacts with nitrous acid to produce nitrogen gas. The reaction temperature in the acid hydrolysis tank 5 is 60℃, and the solution residence time is 30 minutes. The slurry ① that has reached the residence time exits from the overflow outlet E3 of the acid hydrolysis tank 5 and enters the acid hydrolysis buffer tank 7 through the side inlet A4. Under the stirring of the buffer tank agitator 8, the slurry ① continues to react. The reaction temperature in the acid hydrolysis buffer tank 7 is 70℃, and the solution residence time is 30 minutes. The slurry ② that has reached the residence time (containing 9.836% P2O5 by mass, containing Ca) 2+ Mass concentration 9.656%, containing NO3. - The mass concentration of 37.947% flows out of the acid hydrolysis buffer tank 7 through the overflow outlet C4 and enters the settling tank 9 through the side inlet A5. The tail gas that escapes during the reaction is mainly nitrogen and water vapor (containing nitrogen N2 mass concentration of 4.898% and H2O mass concentration of 29.605%), and goes to the boundary area through the top outlet D3 of the feeding acid hydrolysis tank 5 and the top outlet B4 of the acid hydrolysis buffer tank 7.

[0046] (3) Removal of impurities from mixed acid: In the settling tank (9), the clear liquid exits the settling tank (9) from the overflow outlet B5 and enters the mixed acid storage tank (11) through the top inlet B6. The thick slurry exits the settling tank (9) from the bottom outlet C5 and enters the filter (13) through the slurry feed end. In the filter (13), the solids and clear liquid are separated, and the separated solids are washed and separated with process water from the boundary area. The separated clear liquid and washing liquid exit the filter (13) from the liquid outlet end and enter the mixed acid storage tank (11) through the top inlet A6. The separated solids exit the filter (13) from the solid outlet end and are sent to the boundary area as acid insoluble matter through the acid insoluble matter conveyor (14). The solution in the mixed acid storage tank (11) exits the mixed acid storage tank (11) from the side outlet C6 as the target product - mixed acid solution (containing 9.838% P2O5 mass concentration, containing Ca 2+ Mass concentration 9.658%, containing NO3. - The mass concentration of 37.983% was sent to the calcium nitrate crystallization separation system via a mixed acid pump (12);

[0047] The following table shows an example of the results of using this patent.

[0048] Performance Evaluation Results of the 100-ton / hour Nitric Acid Phosphate Fertilizer Plant's System for Producing Mixed Acid Solution by Decomposing Phosphate Rock with Nitric Acid

[0049]

Claims

1. A system for producing a mixed acid solution by decomposing phosphate rock with nitric acid, characterized in that: The system includes a buffer tank agitator (8) and a settling tank (9). Nitric acid pipelines from the boundary area, washing liquid pipelines from the calcium nitrate crystallization separation system, phosphate rock powder conveying pipelines from the boundary area, and urea conveying pipelines from the boundary area are respectively connected to the top of the feeding acid hydrolysis tank (5). The feeding acid hydrolysis tank (5) is connected to the settling tank (9) in sequence through an acid hydrolysis buffer tank (7). The bottom of the settling tank (9) is connected to a filter (13) and an acid-insoluble matter conveyor (14). The top of the settling tank (9) is connected to the mixed acid storage tank (11).

2. The system for producing mixed acid solution by decomposing phosphate rock with nitric acid according to claim 1, characterized in that: Phosphate rock powder from the boundary area is connected to the top of the feeding acid hydrolysis tank (5) via phosphate rock powder storage hopper (1) and phosphate rock powder metering scale (2).

3. The system for producing mixed acid solution by decomposing phosphate rock with nitric acid according to claim 1, characterized in that: Urea from the boundary area is connected to the top of the feeding acid hydrolysis tank (5) via the urea storage hopper (3) and the urea metering scale (4).

4. The system for producing mixed acid solution by decomposing phosphate rock with nitric acid according to claim 1, characterized in that: Both the feeding acid hydrolysis tank (5) and the acid hydrolysis buffer tank (7) are equipped with a stirrer.

5. The system for producing mixed acid solution by decomposing phosphate rock with nitric acid according to claim 1, characterized in that: A settling tank rake (10) is installed in the settling tank (9).

6. The system for producing mixed acid solution by decomposing phosphate rock with nitric acid according to claim 1, characterized in that: The liquid output of the filter (13) is connected to the mixed acid storage tank (11).

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