Enhanced refined phosphoric acid arsenic removal device

Abstract

The utility model provides an intensified refined phosphoric acid arsenic removal device which comprises a hydrolysis tank and a multi-stage intensified refining tower which are connected in sequence, a plurality of intensified units are vertically arranged in the multi-stage intensified refining tower, a gas outlet is formed in the top of the multi-stage intensified refining tower, and a gas outlet is formed in the bottom of the multi-stage intensified refining tower. A liquid phase feeding hole and a gas inlet are formed in the bottom of the multi-stage enhanced refining tower, a circulating feeding hole is also formed in the middle section of the multi-stage enhanced refining tower, and a discharging hole is formed in the bottom of the multi-stage enhanced refining tower; a phosphorus pentasulfide feeding hole and a water inlet are formed in the bottom of the hydrolysis tank, a strengthening unit is arranged at the bottom in the hydrolysis tank, and a hydrogen sulfide outlet is formed in the top of the hydrolysis tank. According to the utility model, the contact area between raw materials is strengthened by using the multi-stage strengthening refining tower, the mass transfer efficiency and the reaction efficiency are improved, the raw materials are converted into microbubbles through the strengthening unit while the hydrolysis of the raw materials is accelerated, so that the retention time between the raw materials is greatly prolonged, and the arsenic removal reaction is fully carried out.

Description

Technical Field

[0001] This utility model belongs to the field of purification technology, specifically relating to an enhanced device for removing arsenic from refined phosphoric acid. Background Technology

[0002] Food-grade phosphoric acid has a wide range of applications in edible gelatin, medical capsules, monosodium glutamate (MSG), toothpaste, beverages, brewing, and many other fields, with high demand. Food-grade phosphoric acid is usually obtained by refining industrial phosphoric acid. However, industrial phosphoric acid production processes typically contain impurities such as arsenic and chlorine. To produce food-grade phosphoric acid, the arsenic content must be reduced to below 0.5 ppm. The basic principle of existing arsenic removal processes is to add sulfide ions to the system, causing them to react with trivalent arsenic to form arsenic trisulfide precipitate, which is then removed by filtration. However, sulfide ions are mostly derived from hydrogen sulfide, sodium sulfide, and phosphorus pentasulfide. To prevent the introduction of sodium ion impurities, sodium sulfide is no longer used in phosphoric acid refining. Hydrogen sulfide is an extremely hazardous gas and unsuitable for industrial applications. Therefore, phosphorus pentasulfide is currently the more ideal sulfide ion donor. The principle is based on the hydrolysis of phosphorus pentasulfide followed by its reaction with arsenic. However, phosphorus pentasulfide is a solid, and its hydrolysis rate in both cold and hot phosphoric acid is relatively slow. Moreover, a significant portion of the converted hydrogen sulfide gas directly escapes from the system into the tail gas under heating conditions, which wastes sulfur and increases the cost of tail gas treatment and safety control. Furthermore, the contact time between the hydrogen sulfide gas converted from its hydrolysis and phosphoric acid is relatively short, resulting in incomplete arsenic removal reaction and affecting the arsenic removal effect of phosphoric acid.

[0003] In view of the above, this utility model is hereby proposed. Summary of the Invention

[0004] The primary objective of this invention is to provide an enhanced purification phosphoric acid arsenic removal device. This device enhances the contact area between raw materials by using a multi-stage enhanced purification tower, thereby improving mass transfer efficiency and reaction efficiency. While accelerating the hydrolysis of raw materials, the enhanced unit converts the raw materials into microbubbles, which greatly extends the residence time between the raw materials, allowing the arsenic removal reaction to proceed fully.

[0005] In order to achieve the above-mentioned objectives of this utility model, the following technical solution is adopted:

[0006] An enhanced purification and arsenic removal device for phosphoric acid includes a hydrolysis tank and a multi-stage enhanced purification tower connected in sequence. The multi-stage enhanced purification tower has multiple enhanced units vertically arranged inside. The top of the multi-stage enhanced purification tower has a gas outlet, the bottom of the multi-stage enhanced purification tower has a liquid feed inlet and a gas inlet, and the multi-stage enhanced purification tower also has a circulating feed inlet. The bottom of the multi-stage enhanced purification tower has a phosphorus pentasulfide feed inlet and a water inlet. The bottom of the hydrolysis tank has enhanced units arranged inside the tank, and the top of the hydrolysis tank has a hydrogen sulfide gas outlet connected to the gas inlet.

[0007] In this invention, a better arsenic removal effect of phosphoric acid is achieved by combining a hydrolysis tank and a multi-stage enhanced refining tower. Specifically, by using a hydrolysis tank to first hydrolyze the raw material phosphoric acid pentasulfide, a better arsenic removal effect is achieved. This is because among existing arsenic removal agents, only phosphoric acid pentasulfide is both effective and safe. However, phosphoric acid pentasulfide is extremely difficult to dissolve; it is insoluble or dissolves very slowly in both cold and hot phosphoric acid. Therefore, traditional arsenic removal methods that directly mix phosphoric acid pentasulfide with phosphoric acid suffer from extremely slow reaction rates, low efficiency, poor safety, and low hydrogen sulfide utilization. Therefore, in order to accelerate the arsenic removal rate of phosphoric acid, while ensuring high safety and achieving high hydrogen sulfide utilization, this invention first introduces the raw material phosphorus pentasulfide and water into a hydrolysis tank. The enhanced unit in the hydrolysis tank accelerates the effect of phosphorus pentasulfide, enabling it to quickly generate a large amount of hydrogen sulfide gas. Subsequently, the hydrogen sulfide gas flows out from the hydrogen sulfide outlet at the top of the hydrolysis tank and is introduced into the enhanced refining tower through the inlet for the arsenic removal reaction. In this way, the utilization rate of phosphorus pentasulfide can be greatly improved, and the arsenic removal effect can be significantly enhanced.

[0008] Preferably, as a further feasible option, the multi-stage enhanced refining tower is a two-stage enhanced refining tower, which includes a primary refining tower and a secondary refining tower.

[0009] Preferably, as a further feasible option, the primary refining tower is provided with two intensifier units, wherein the two intensifier units are a first intensifier unit and a second intensifier unit, the first intensifier unit is located at the bottom of the primary refining tower, and the second intensifier unit is located at the top of the primary refining tower; the circulating feed inlet is located above the second intensifier unit; the liquid phase feed inlet and the air inlet are connected to the first intensifier unit; a sieve plate is provided above the first intensifier unit, and a spray layer is provided above the second intensifier unit.

[0010] Preferably, as a further feasible option, a third intensifier unit is provided at the top of the secondary refining tower, and a feed inlet is provided above the third intensifier unit, which is connected to the gas outlet; a first circulation feed inlet and a second circulation feed inlet are also provided on the middle sections of both sides of the secondary refining tower, and a discharge outlet is also provided at the bottom of the secondary refining tower.

[0011] This invention primarily employs a two-stage enhanced refining tower, comprising a primary refining tower and a secondary refining tower. Two intensifying units are installed within the primary refining tower, designated as the first intensifying unit and the second intensifying unit. The first intensifying unit is located at the bottom of the primary refining tower, while the second intensifying unit is located at the top. Phosphorus pentasulfide and phosphoric acid are introduced into the primary refining tower through the liquid and solid inlets located at the bottom. Upon introduction into the refining tower, phosphorus pentasulfide undergoes vigorous hydrolysis upon contact with water, generating a large amount of hydrogen sulfide gas. The hydrogen sulfide gas and phosphoric acid... The hydrogen sulfide gas is introduced into the first intensifier unit. After being processed by the first intensifier unit, the hydrogen sulfide gas is broken into microbubbles, which can be evenly dispersed in the phosphoric acid liquid. By reducing the size of the hydrogen sulfide gas, the contact area and reaction time between hydrogen sulfide and phosphoric acid are increased, making the arsenic removal reaction more complete. In addition, this invention also sets a sieve plate above the first intensifier unit. Since the sieve plate has evenly distributed funnel-shaped guide ports with guiding function, it ensures that the hydrogen sulfide broken into microbubbles can be dispersed to both sides, avoiding the irregular dispersion of hydrogen sulfide due to excessive accumulation of microbubbles in the center of the reactor, which would affect the arsenic removal effect of phosphoric acid.

[0012] After passing through the primary refining tower, the reaction liquid gradually rises. It then passes through a second intensifying unit located at the top of the primary refining tower to further enhance the arsenic removal efficiency of hydrogen sulfide from phosphoric acid. Simultaneously, the first circulating pump extracts the reaction liquid from the tower and re-enters it through the circulating feed inlet. There, it is sprayed through a spray layer above the second intensifying unit, achieving initial breakup of the reaction liquid. This allows the reaction liquid circulating from the top to initially form a stable gas-liquid mixture. As the reaction liquid descends through the primary refining tower, the residence time of hydrogen sulfide gas in the phosphoric acid is increased. Consequently, when the reaction liquid recirculates back into the primary refining tower, the hydrogen sulfide gas, after being processed by the second intensifying unit, is more evenly dispersed in the phosphoric acid, further improving the arsenic removal effect of the phosphoric acid.

[0013] Subsequently, the unreacted hydrogen sulfide gas flows out from the outlet at the top of the primary refining tower, and then enters the secondary refining tower through the feed inlet at the top of the secondary refining tower. It is then introduced into the third enhancement unit together with the reaction liquid introduced from the first circulation feed inlet. This process breaks the unreacted hydrogen sulfide gas into microbubbles, which mix with the introduced reaction liquid, increasing the residence time of hydrogen sulfide in phosphoric acid and increasing the contact area between the two, thereby improving the arsenic removal effect of phosphoric acid.

[0014] Therefore, this invention further increases the contact area and contact time between raw materials by setting up a multi-stage enhanced refining tower, combined with the setting of sieve plates and spray layers, which greatly improves the efficiency of the arsenic removal reaction. Compared with the prior art, the arsenic removal device used in this invention can effectively avoid the danger caused by the direct use of hydrogen sulfide, and has excellent arsenic removal effect, fast reaction rate and excellent arsenic removal effect.

[0015] Preferably, as a further feasible option, a first circulating pump is provided between the circulating feed inlet and the discharge outlet, and the first circulating pump is connected to the first circulating feed inlet.

[0016] Preferably, as a further feasible option, the discharge port at the bottom of the secondary refining tower is connected to the second circulating feed port, and a second circulating pump is also provided between the discharge port and the second circulating feed port.

[0017] Preferably, as a further feasible option, a separation tower is also included; the separation tower is connected to the secondary purification tower via the second circulating pump.

[0018] Preferably, as a further feasible option, the top of the separation tower is provided with an exhaust gas outlet, and the bottom of the separation tower is provided with a discharge port and a circulating pump inlet on both sides, respectively, and the circulating pump inlet is connected to the second circulating pump.

[0019] Preferably, as a further feasible option, the separation tower is provided with packing material, and the distance between the packing material and the top of the separation tower is 2-3 times the distance between the packing material and the bottom of the separation tower.

[0020] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0021] (1) The present invention provides an enhanced refined phosphoric acid arsenic removal device. The arsenic removal device enhances the contact area between raw materials by using a multi-stage enhanced refining tower, thereby improving mass transfer efficiency and reaction efficiency. While accelerating the hydrolysis of raw materials, the enhanced unit converts the raw materials into microbubbles, thereby greatly extending the residence time between raw materials and allowing the arsenic removal reaction to proceed fully. Attached Figure Description

[0022] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0023] Figure 1 This invention relates to an enhanced arsenic removal device for refined phosphoric acid, as provided in Embodiment 1 of this utility model.

[0024] Figure 1 The list of components represented by each number is as follows:

[0025] 1. Primary refining tower; 2. First intensifier unit; 3. Spray layer; 4. Second intensifier unit; 5. Sieve plate; 6. First circulating pump; 7. Secondary refining tower; 8. Third intensifier unit; 9. Second circulating pump; 10. Packing; 11. Separation tower; 12. Intensifier unit; 13. Hydrolysis tank. Detailed Implementation

[0026] The technical solution of this utility model will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are only some embodiments of this utility model, not all embodiments, and are only used to illustrate this utility model, and should not be regarded as limiting the scope of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0027] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0029] To more clearly illustrate the technical solution of this utility model, the following description is provided in the form of specific embodiments.

[0030] Example 1

[0031] Please see Figure 1 This utility model is an enhanced purification and arsenic removal device for phosphoric acid, comprising: 1. a primary purification tower; 2. a first enhancement unit; 3. a spray layer; 4. a second enhancement unit; 5. a sieve plate; 6. a first circulating pump; 7. a secondary purification tower; 8. a third enhancement unit; 9. a second circulating pump; 10. packing; 11. a separation tower; 12. an enhancement unit; and 13. a hydrolysis tank.

[0032] In this utility model, the first strengthening unit, the second strengthening unit and the third strengthening unit are all gas-liquid linkage micro-interface generators, while the strengthening unit is a solid-liquid linkage micro-interface generator.

[0033] In the enhanced refined phosphoric acid arsenic removal device of this utility model, it mainly includes a hydrolysis tank 13, a primary refining tower 1 and a secondary refining tower 7 connected in sequence. The bottom of the hydrolysis tank 13 is provided with a phosphorus pentasulfide feed inlet and a water inlet, and an enhanced unit 12 is provided at the bottom of the hydrolysis tank 13.

[0034] Two intensifier units are installed in the primary refining tower 1, namely the first intensifier unit 2 and the second intensifier unit 4. The first intensifier unit 2 is located below the circulating feed inlet, and a liquid feed inlet and a solid feed inlet are provided at the bottom of the primary refining tower. A sieve plate 5 is provided above the first intensifier unit, and funnel-shaped guide ports are evenly distributed on the sieve plate 5. A spray layer 3 is provided above the second intensifier unit.

[0035] The top of the secondary refining tower 7 is equipped with a third intensifier unit 8, and a feed inlet is provided above the third intensifier unit 8. The feed inlet above the third intensifier unit 8 is connected to the discharge outlet provided at the top of the primary refining tower 1. The middle sections on both sides of the secondary refining tower 7 are respectively equipped with a first circulation feed inlet and a second circulation feed inlet, and a discharge outlet is provided at the bottom of the secondary refining tower 7.

[0036] Furthermore, a first circulation pump 6 is installed between the circulation inlet on the first-stage refining tower and the discharge outlet at the bottom of the first-stage refining tower, and the first circulation pump 6 is connected to the first circulation inlet on the side of the middle section of the second-stage refining tower 7.

[0037] The discharge port at the bottom of the secondary refining tower 7 is connected to the second circulation feed port on the side of the primary refining tower, and a second circulation pump 9 is installed between the discharge port and the second circulation feed port.

[0038] The present invention also includes a separation tower 11, which is connected to the secondary refining tower 7 via the second circulation pump 9. The top of the separation tower is provided with a tail gas outlet, and the bottom of the separation tower is provided with a feed inlet and a circulation pump feed inlet on both sides, respectively. The circulation pump feed inlet is connected to the second circulation pump 9. Furthermore, a packing material 10 is provided inside the separation tower, and the distance between the packing material and the bottom of the separation tower 10 is twice the distance between the packing material and the top of the separation tower 10.

[0039] The specific steps of the arsenic removal method of this utility model are as follows: Water and phosphorus pentasulfide are introduced into the hydrolysis tank 13 through the phosphorus pentasulfide feed port and water inlet respectively set at the bottom of the hydrolysis tank 13. Subsequently, due to the setting of the intensifier unit 12, the hydrolysis speed of phosphorus pentasulfide is accelerated, which causes it to form a large amount of hydrogen sulfide gas. Then, the hydrogen sulfide gas formed by hydrolysis will flow out from the hydrolysis tank and enter the first intensifier unit 2 in the first-stage purification tower 1 through the gas inlet set on the side of the first-stage purification tower 1 and the phosphoric acid introduced through the liquid phase feed port. After being processed by the first intensifier unit 2, the hydrogen sulfide gas is broken into microbubbles and then evenly dispersed in the phosphoric acid through the sieve plate 5 set above the first intensifier unit. In this way, the residence time and contact area of ​​hydrogen sulfide in phosphoric acid can be greatly increased.

[0040] Subsequently, the first circulating pump 6 draws the reaction liquid from the bottom of the first-stage refining tower 1 and re-enters the first-stage refining tower 1 through the circulating feed port set at the top of the first-stage refining tower 1. The reaction liquid is then initially broken up by the spray layer 3 set above the second intensifier unit 4, so that the hydrogen sulfide gas is dispersed in the reaction liquid to form a uniform mixture. Then, it enters the second intensifier unit 4 together. After being processed by the second intensifier unit 4, the hydrogen sulfide gas can be further evenly dispersed in the reaction liquid, further improving the arsenic removal effect.

[0041] The unreacted hydrogen sulfide gas will flow out from the outlet at the top of the primary refining tower 1 and enter the secondary refining tower 7 through the feed inlet at the top of the secondary refining tower 7. It will then enter the secondary refining tower 7 together with the reaction liquid drawn out by the first circulating pump 6. After being processed by the third intensifier unit 8, the hydrogen sulfide gas will be evenly dispersed in the reaction liquid, so that the hydrogen sulfide can be further reacted completely.

[0042] Subsequently, the second circulation pump 9 will extract the reaction liquid inside the secondary purification tower 7 and enter the secondary purification tower 7 through the second circulation feed port set at the top of the secondary purification tower 7 for further arsenic removal reaction;

[0043] After being processed by the secondary purification tower 7, the reaction liquid is pumped out by the second circulation pump 9 and sent to the separation tower 11. The reaction liquid is separated into gas and liquid by the packing 10. After the arsenic removal is completed, the reaction liquid is discharged from the outlet at the bottom of the separation tower 10, and the tail gas is discharged from the tail gas outlet at the top.

[0044] Example 2

[0045] In the enhanced refined phosphoric acid arsenic removal device of this utility model, it mainly includes a hydrolysis tank 13, a primary refining tower 1 and a secondary refining tower 7 connected in sequence. The bottom of the hydrolysis tank 13 is provided with a phosphorus pentasulfide feed inlet and a water inlet, and an enhanced unit 12 is provided at the bottom of the hydrolysis tank 13.

[0046] Two intensifier units are installed in the primary refining tower 1, namely the first intensifier unit 2 and the second intensifier unit 4. The first intensifier unit 2 is located below the circulating feed inlet, and a liquid feed inlet and a solid feed inlet are provided at the bottom of the primary refining tower. A sieve plate 5 is provided above the first intensifier unit, and funnel-shaped guide ports are evenly distributed on the sieve plate 5. A spray layer 3 is provided above the second intensifier unit.

[0047] The top of the secondary refining tower 7 is equipped with a third intensifier unit 8, and a feed inlet is provided above the third intensifier unit 8. The feed inlet above the third intensifier unit 8 is connected to the discharge outlet provided at the top of the primary refining tower 1. The middle sections on both sides of the secondary refining tower 7 are respectively equipped with a first circulation feed inlet and a second circulation feed inlet, and a discharge outlet is provided at the bottom of the secondary refining tower 7.

[0048] Furthermore, a first circulation pump 6 is installed between the circulation inlet on the first-stage refining tower and the discharge outlet at the bottom of the first-stage refining tower, and the first circulation pump 6 is connected to the first circulation inlet on the side of the middle section of the second-stage refining tower 7.

[0049] The discharge port at the bottom of the secondary refining tower 7 is connected to the second circulation feed port on the side of the primary refining tower, and a second circulation pump 9 is installed between the discharge port and the second circulation feed port.

[0050] The present invention also includes a separation tower 11, which is connected to the secondary refining tower 7 via the second circulation pump 9. The top of the separation tower is provided with a tail gas outlet, and the bottom of the separation tower is provided with a feed inlet and a circulation pump feed inlet on both sides, respectively. The circulation pump feed inlet is connected to the second circulation pump 9. Furthermore, a packing material 10 is provided inside the separation tower, and the distance between the packing material and the bottom of the separation tower 10 is three times the distance between the packing material and the top of the separation tower 10.

[0051] The specific steps of the arsenic removal method of this utility model are as follows: Water and phosphorus pentasulfide are introduced into the hydrolysis tank 13 through the phosphorus pentasulfide feed port and water inlet respectively set at the bottom of the hydrolysis tank 13. Subsequently, due to the setting of the intensifier unit 12, the hydrolysis speed of phosphorus pentasulfide is accelerated, causing it to form a large amount of hydrogen sulfide gas. Then, the hydrogen sulfide gas formed by hydrolysis will flow out from the hydrolysis tank and enter the first intensifier unit 2 in the first-stage purification tower 1 through the gas inlet set on the side of the first-stage purification tower 1 and the phosphoric acid introduced through the liquid phase feed port. After being processed by the first intensifier unit 2, the hydrogen sulfide gas is broken into microbubbles and then evenly dispersed in the phosphoric acid through the sieve plate 5 set above the first intensifier unit. In this way, the residence time and contact area of ​​hydrogen sulfide in phosphoric acid can be greatly increased.

[0052] Subsequently, the first circulating pump 6 draws the reaction liquid from the bottom of the first-stage refining tower 1 and re-enters the first-stage refining tower 1 through the circulating feed port set at the top of the first-stage refining tower 1. The reaction liquid is then initially broken up by the spray layer 3 set above the second intensifier unit 4, so that the hydrogen sulfide gas is dispersed in the reaction liquid to form a uniform mixture. Then, it enters the second intensifier unit 4 together. After being processed by the second intensifier unit 4, the hydrogen sulfide gas can be further evenly dispersed in the reaction liquid, further improving the arsenic removal effect.

[0053] The unreacted hydrogen sulfide gas will flow out from the outlet at the top of the primary refining tower 1 and enter the secondary refining tower 7 through the feed inlet at the top of the secondary refining tower 7. It will then enter the secondary refining tower 7 together with the reaction liquid drawn out by the first circulating pump 6. After being processed by the third intensifier unit 8, the hydrogen sulfide gas will be evenly dispersed in the reaction liquid, so that the hydrogen sulfide can be further reacted completely.

[0054] Subsequently, the second circulation pump 9 will extract the reaction liquid inside the secondary purification tower 7 and enter the secondary purification tower 7 through the second circulation feed port set at the top of the secondary purification tower 7 for further arsenic removal reaction;

[0055] After being processed by the secondary purification tower 7, the reaction liquid is pumped out by the second circulation pump 9 and sent to the separation tower 11. The reaction liquid is separated into gas and liquid by the packing 10. After the arsenic removal is completed, the reaction liquid is discharged from the outlet at the bottom of the separation tower 10, and the tail gas is discharged from the tail gas outlet at the top.

[0056] Experiment Example 1: Verifying the feasibility of the arsenic removal experiment from phosphorus pentasulfide.

[0057] The feed solution temperature was 75-80℃. The theoretical requirement of P2S5 was calculated based on the reaction equation. Then, experiments were conducted with feed amounts of 4, 8, 12, and 16 times the theoretical requirement, with a reaction time of 30 minutes. The arsenic removal effect of different P2S5 amounts was investigated, and the results are shown in Table 1.

[0058] Table 1. Effect of different P2S5 feed amounts on arsenic removal efficiency

[0059]

[0060] The results analysis reveals that while 16 times the recommended dosage was close to the requirement, it did not completely meet the arsenic removal needs, while dosages of 4, 8, and 12 times the recommended dosage showed poor arsenic removal effects. Further analysis based on the experimental phenomena suggests two main reasons: firstly, the experiment used hot water for initial hydrolysis to accelerate P2S5 hydrolysis, resulting in a significant amount of H2S being released and wasted. Secondly, the excess of P2S5, meaning the phosphoric acid contained excessive sulfur, contributed to the problem. 2- The remaining As2S3 precipitates that have already formed combine to form polysulfides and redissolve. Therefore, the above experimental results show that phosphorus pentasulfide has a certain effect on the removal of arsenic from phosphoric acid, but due to its low hydrolysis efficiency and low H2S utilization rate, the removal efficiency of phosphorus pentasulfide is not high.

[0061] Table 2 Verification of Arsenic Removal Performance under Enhanced Unit Conditions

[0062] Through equipment debugging and improvements to the P2S5 feeding method, the equipment achieved continuous and stable operation. Based on this, continuous operation monitoring was conducted for several days, with samples taken every 30 minutes and 60 minutes. After removing the As2S3 precipitate via membrane separation, the arsenic content in the phosphoric acid was measured, as shown in Table 2 below.

[0063] Table 2 Results of continuous arsenic removal operation test of arsenic removal equipment

[0064]

[0065] Table 2 shows that the enhanced unit can achieve continuous and stable removal of arsenic from crude phosphoric acid. Furthermore, compared to arsenic removal equipment without the enhanced unit, the removal time with the enhanced unit is approximately 30-35 minutes, indicating that the enhanced unit can shorten the arsenic removal reaction time. This is because the enhanced unit effectively improves the hydrolysis efficiency of phosphorus pentasulfide and increases the gas-liquid contact reaction rate during the reaction between sulfur and arsenic, thereby improving reaction efficiency and shortening the reaction time.

[0066] The data from the second experiment in Table 2 also show that, compared to Experiment 1 which required approximately 16 times the amount of P2S5 to achieve a good arsenic removal effect, the device of this invention can significantly reduce the amount of P2S5 used. Therefore, based on the results of the pilot-scale arsenic removal experiment, in industrial production, the arsenic removal equipment designed according to this invention can effectively reduce the amount of P2S5 used, improve equipment safety, and reduce pollutant gas emissions; it can also shorten the reaction residence time and improve the processing efficiency of the equipment.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. An enhanced arsenic removal device for refined phosphoric acid, characterized in that, The system includes a hydrolysis tank and a multi-stage enhanced refining tower connected in sequence. The multi-stage enhanced refining tower contains multiple enhanced units arranged vertically. The top of the multi-stage enhanced refining tower has a gas outlet, the bottom has a liquid feed inlet and a gas inlet, a circulating feed inlet, and a discharge outlet. The bottom of the hydrolysis tank has a phosphorus pentasulfide feed inlet and a water inlet. The bottom of the hydrolysis tank contains enhanced units, and the top of the hydrolysis tank has a hydrogen sulfide gas outlet connected to the gas inlet.

2. The enhanced arsenic removal apparatus for refined phosphoric acid according to claim 1, characterized in that, The multi-stage strengthening and refining tower is a two-stage strengthening and refining tower, which includes a first-stage refining tower and a second-stage refining tower.

3. The enhanced arsenic removal apparatus for refined phosphoric acid according to claim 2, characterized in that, The primary refining tower is equipped with two intensifying units, namely a first intensifying unit and a second intensifying unit. The first intensifying unit is located at the bottom of the primary refining tower, and the second intensifying unit is located at the top of the primary refining tower. The circulating feed inlet is located above the second intensifying unit. The liquid phase feed inlet and the air inlet are connected to the first intensifying unit. A sieve plate is provided above the first intensifying unit, and a spray layer is provided above the second intensifying unit.

4. The enhanced arsenic removal apparatus for refined phosphoric acid according to claim 2, characterized in that, The top of the secondary refining tower is equipped with a third intensifier unit, and a feed inlet is provided above the third intensifier unit. The feed inlet is connected to the air outlet. The middle sections on both sides of the secondary refining tower are also equipped with a first circulation feed inlet and a second circulation feed inlet, respectively. The bottom of the secondary refining tower is also equipped with a discharge outlet.

5. The enhanced arsenic removal apparatus for refined phosphoric acid according to claim 4, characterized in that, A first circulation pump is also provided between the circulation inlet and the outlet, and the first circulation pump is connected to the first circulation inlet.

6. The enhanced arsenic removal apparatus for refined phosphoric acid according to claim 4, characterized in that, The discharge port at the bottom of the secondary refining tower is connected to the second circulating feed port, and a second circulating pump is also provided between the discharge port and the second circulating feed port.

7. The enhanced arsenic removal apparatus for refined phosphoric acid according to claim 6, characterized in that, It also includes a separation tower; the separation tower is connected to the secondary refining tower via the second circulating pump.

8. The enhanced arsenic removal apparatus for refined phosphoric acid according to claim 7, characterized in that, The top of the separation tower is provided with an exhaust gas outlet, and the bottom of the separation tower is provided with a discharge port and a circulating pump inlet on both sides, respectively. The circulating pump inlet is connected to the second circulating pump.

9. The enhanced arsenic removal apparatus for refined phosphoric acid according to claim 8, characterized in that, The separation tower is equipped with packing material, and the distance between the packing material and the bottom of the separation tower is 2-3 times the distance between the packing material and the top of the separation tower.

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