A high-benefit utilization process for wet-process phosphoric acid slurry and its recovery device

Abstract

The present invention provides a process for the highly efficient utilization of wet-process phosphoric acid slurry and its recovery device, belonging to the technical field of wet-process phosphoric acid preparation, which includes the following steps: S1. Stir the concentrated phosphoric acid slurry in the slurry collection tank evenly, and transport the concentrated phosphoric acid slurry to a filter press through a slurry pump for primary filtration. The concentrated phosphoric acid obtained after filtration is transported to a concentrated phosphoric acid buffer tank through a concentrated phosphoric acid pipeline for the production of high-benefit phosphoric acid products; S2. After the primary filtration is completed, continuously introduce washing water for secondary filtration for 200 - 300 s. Within the first 100 - 140 s, the dilute phosphoric acid enters the dilute phosphoric acid buffer tank; S3. During the remaining time, the filter cloth washing water enters the filter cloth washing water tank; S4. After the secondary filtration, unload the filter residue gypsum, and the filter cloth washing water rinses the filter cloth, and the rinsing liquid enters the rinsing liquid collection tank. This process not only realizes the highly efficient utilization of P2O5 in the slurry, comprehensively utilizes the phosphogypsum residue, truly achieves the complete utilization of the crude phosphoric acid slurry, but also realizes the zero discharge of wastewater during the slurry recovery and treatment process.

Description

Technical Field

[0001] The present invention relates to the technical field of wet-process phosphoric acid preparation, and particularly to a process for highly efficient utilization of wet-process phosphoric acid slurry and a recovery device thereof. Background Art

[0002] In the production process of wet-process phosphoric acid by decomposing phosphate rock with sulfuric acid, various metal elements such as iron, magnesium, aluminum, sodium, and potassium brought into the production system by the phosphate rock are mixed into the concentrated phosphoric acid solution in the form of soluble salts. When the concentrated phosphoric acid is clarified in the storage tank, the metal elements settle down in the form of successive precipitates to become slurry.

[0003] Due to the high viscosity of the slurry, it deposits at the bottom of the phosphoric acid storage tank and needs to be removed in time. Otherwise, the rotating rake in the phosphoric acid storage tank will be buried, causing production system failures. In order to ensure smooth slurry transportation, it is necessary to control the solid content of the slurry. The highest control index is generally only about 15%, and about 40% is P2O5.

[0004] The traditional method for treating slurry is to return the settled slurry to the clarified phosphoric acid solution by reflux, and then send it out for producing phosphoric acid ammonium products. However, due to the high impurity content in the slurry, when it is returned to the clarified raw phosphoric acid, it affects the product quality of phosphoric acid ammonium. Thus, the phosphoric acid slurry cannot be treated by reflux. Currently, there are mainly two ways to transport and use the slurry: one is to produce low-nutrient phosphoric acid ammonium products, such as diammonium phosphate with nutrient contents of 53% and 57%; the other is to return it to the phosphoric acid reaction and filtration system for recycling.

[0005] Using the slurry to produce low-nutrient phosphoric acid ammonium products has a low marginal contribution and even incurs losses. The purpose is to convert the slurry into a product for use. Then, when the slurry is sent back to the phosphoric acid reaction and filtration system for recovery, due to the high content of concentrated phosphoric acid in the slurry, in order to control the reaction index, a large amount of washing water has to be used to dilute the concentrated phosphoric acid into dilute phosphoric acid, and then concentrated again to produce slurry. In this way, water, electricity, and steam are continuously wasted. The slurry circulates repeatedly in the production system, and metal ions such as iron, magnesium, aluminum, sodium, and potassium in the phosphoric acid are continuously enriched, resulting in serious system scaling, difficult operation, and difficult control of the phosphoric acid product quality. At the same time, the successive precipitates in the slurry are difficult to filter. After entering the reaction and filtration system, it will also cause a high residual phosphorus content in the phosphogypsum of the phosphoric acid filter, resulting in large production cost losses. Obviously, it is also not feasible to recycle the slurry by returning it to the phosphoric acid reaction and filtration system.

[0006] Based on an annual output of 300,000 tons of P2O5, when the solid content of the concentrated acid is 3%, the concentration is 47.5%, the specific gravity of the slurry is 1.782, the solid content of the slurry is 15%, and the percentage content of P2O5 in the slurry is 40.38%, the annual output of the slurry is approximately 126,300 tons, and the amount of P2O5 contained in the slurry is approximately 51,000 tons. The content of P2O5 in the concentrated phosphoric acid slurry is quite high. If not utilized well, this is a huge waste. Therefore, it is necessary to seek channels for the efficient utilization of the slurry and also find methods to reduce the impurity content in phosphoric acid. Summary of the Invention

[0007] To overcome the problems existing in the related technologies, the object of the present invention is to provide a process for the highly efficient utilization of wet-process phosphoric acid slurry.

[0008] A process for the highly efficient utilization of wet-process phosphoric acid slurry.

[0009] It includes the following steps:

[0010] S1. Stir the concentrated phosphoric acid slurry in the slurry collection tank evenly, and use a slurry pump to transport the concentrated phosphoric acid slurry to a filter press for primary filtration. The concentrated phosphoric acid obtained after filtration is transported to a concentrated phosphoric acid buffer tank through a concentrated phosphoric acid pipeline for the production of high-benefit phosphoric acid products.

[0011] S2. After the primary filtration is completed, continuously introduce washing water into the filter press for secondary filtration for 200 - 300 s; within 100 - 140 s before the secondary filtration, the dilute phosphoric acid obtained after washing enters the dilute phosphoric acid buffer tank through a dilute phosphoric acid pipeline.

[0012] At this time, close the regulating valve on the concentrated phosphoric acid pipeline and open the regulating valve on the dilute phosphoric acid pipeline to transport the dilute phosphoric acid to the dilute phosphoric acid buffer tank.

[0013] S3. During the remaining time of the secondary filtration, the filter cloth flushing water obtained from washing enters the filter cloth flushing water tank through a filter cloth flushing pipeline.

[0014] At this time, close the regulating valve on the dilute phosphoric acid pipeline and open the regulating valve on the filter cloth flushing pipeline to transport the filter cloth flushing water to the filter cloth flushing water tank.

[0015] Since during the secondary filtration washing process, the concentration gradient of the washing liquid obtained after washing changes greatly, in the initial stage of washing, the phosphorus content in the washing liquid is relatively high. Introduce the washing liquid into the dilute phosphoric acid buffer tank. Due to the small amount, the filtration time is controlled very short; the washing liquid mainly serves to wash the residual water-soluble phosphorus in the filtered gypsum and as the filter cloth flushing water.

[0016] S4. After the secondary filtration, unload the filter residue gypsum, and use the filter cloth flushing water in the filter cloth flushing water tank from a filter cloth flushing pump to flush the filter cloth of the filter press. The flushing liquid after flushing enters the flushing liquid collection tank through a flushing liquid pipeline.

[0017] Under the agitation of the stirrer in the flushing liquid collection tank, the flushing liquid is sent to the filter in the phosphoric acid workshop by the flushing water pump for use as flushing water.

[0018] The filter residue gypsum is sent to the yard and screened by the screening machine. After screening, the fine powder will enter the return belt of the DAP production workshop and be used as the raw material for producing DAP products; it is used as an additive for producing DAP products with a nutrient content of 53% or 57%.

[0019] Through continuous feeding - pressure filtration - washing - slag discharging - flushing, and so on in a cycle, after the first - stage pressure filtration and the second - stage pressure filtration of the concentrated phosphoric acid slurry are completed, the system is regularly cleaned and inspected. After the system has been running for a period of time, by preparing the cleaning liquid, a full - process cleaning of the system is carried out to ensure the regeneration effect of the filter cloth and the scale removal of the pipeline.

[0020] In a preferred technical solution of the present invention, the solid content of the concentrated phosphoric acid slurry is 3 - 10%; the specific gravity of the concentrated phosphoric acid slurry is 1.7 - 1.9; the P2O5 content of the concentrated phosphoric acid slurry is 38 - 43%.

[0021] In a preferred technical solution of the present invention, the filter press is a vertical filter press or a horizontal filter press. Preferably, the filter press is a vertical filter press.

[0022] In a preferred technical solution of the present invention, the pressure of the filter press for pressure filtration is 10 - 16 MPa. Preferably, the pressure of the filter press for pressure filtration is 12 MPa.

[0023] In a preferred technical solution of the present invention, the pressure of the first - stage pressure filtration is 10 - 16 MPa. Preferably, the pressure of the first - stage pressure filtration is 12 MPa.

[0024] In a preferred technical solution of the present invention, the pressure of the second - stage pressure filtration is 10 - 16 MPa. Preferably, the pressure of the second - stage pressure filtration is 12 MPa.

[0025] In a preferred technical solution of the present invention, the duration of the first - stage pressure filtration is 120 - 180 s.

[0026] In a preferred technical solution of the present invention, the slurry pump is a high - lift slurry pump, and the lift of the slurry pump is ≥70 m.

[0027] In a preferred technical solution of the present invention, the filter cloth flushing pump is a high - lift flushing pump, and the lift of the filter cloth flushing pump is ≥70 m.

[0028] In a preferred technical solution of the present invention, the flow rate of the washing water is 30 - 45 m 3 / h.

[0029] In a preferred technical solution of the present invention, the concentrated phosphoric acid buffer tank and the dilute phosphoric acid buffer tank are respectively connected to the concentrated phosphoric acid tank and the dilute phosphoric acid tank through a transfer pump, and the flushing liquid collection tank is connected to the workshop flushing water tank through a flushing water pump;

[0030] The present invention also provides a recovery device for highly efficient utilization of wet-process phosphoric acid slurry,

[0031] including a slurry collection tank, a slurry stirrer, a slurry pump, a filter press, a concentrated phosphoric acid pipeline, a concentrated phosphoric acid buffer tank, a dilute phosphoric acid pipeline, a dilute phosphoric acid buffer tank, a filter cloth flushing pipeline, a filter cloth flushing water tank, a filter cloth flushing pump, a flushing liquid pipeline, and a flushing liquid collection tank;

[0032] The slurry stirrer is arranged in the slurry collection tank. The inlet end of the slurry pump is connected to the bottom of the slurry collection tank through a pipeline, and the outlet end of the slurry pump is connected to the filter press through a pipeline;

[0033] The concentrated phosphoric acid pipeline connects the filter press and the concentrated phosphoric acid buffer tank, the dilute phosphoric acid pipeline connects the filter press and the dilute phosphoric acid buffer tank, and the filter cloth flushing pipeline connects the filter press and the filter cloth flushing water tank; the flushing liquid collection tank is connected to the filter press through a flushing liquid pipeline;

[0034] The inlet end of the filter cloth flushing pump is connected to the bottom of the filter cloth flushing water tank through a pipeline, and the outlet end of the filter cloth flushing pump is connected to the filter press through a pipeline.

[0035] In a preferred technical solution of the present invention, a flushing liquid stirrer is arranged in the flushing liquid collection tank, and the bottom of the flushing liquid collection tank is connected to the flushing water pump.

[0036] In a preferred technical solution of the present invention, the filter press is a vertical filter press or a horizontal filter press. Preferably, the filter press is a vertical filter press;

[0037] In a preferred technical solution of the present invention, the filtration pressure of the filter press is 10 - 16 MPa. Preferably, the filtration pressure of the filter press is 12 MPa.

[0038] In a preferred technical solution of the present invention, the slurry pump is a high-lift slurry pump, and the lift of the slurry pump is ≥ 70 m.

[0039] In a preferred technical solution of the present invention, the filter cloth flushing pump is a high-lift flushing pump, and the lift of the filter cloth flushing pump is ≥ 70 m.

[0040] In a preferred technical solution of the present invention, the concentrated phosphoric acid buffer tank and the dilute phosphoric acid buffer tank are respectively connected to the concentrated phosphoric acid tank and the dilute phosphoric acid tank through a transfer pump, and the flushing liquid collection tank is connected to the workshop flushing water tank through a flushing water pump;

[0041] The beneficial effects of the present invention are:

[0042] The high-benefit utilization process of wet-process phosphoric acid slurry and its recovery device provided by the present invention

[0043] Separate P2O5 in the slurry for the production of high-end phosphochemical products, greatly enhancing the utilization value of P2O5, while using filter residue gypsum for the production of phosphoammonium products with relatively low marginal contribution, improving the high-value utilization of the slurry, and thus achieving the purpose of maximizing the utilization benefit of phosphoric acid slurry;

[0044] Phosphates of various metal elements such as iron, magnesium, aluminum, sodium, and potassium brought into the production system by phosphate rock precipitate as slurry in the form of successive precipitates in the phosphoric acid production system. After being treated by this process, the successive precipitates of metal elements are removed from the production system and do not circulate and accumulate in the production system, making the product quality control more stable. At the same time, it can also alleviate the scaling of the production system; the total phosphorus in the filter residue gypsum decreases, the scaling of the storage tank slows down, and the product quality is better controlled;

[0045] After extracting concentrated phosphoric acid from the slurry, washing of the sludge filter cake is provided, with cascade distribution and recycling of the washing acid and recycling of the washing water. It not only realizes high recovery rate and effective utilization rate of P2O5, but also realizes zero discharge of wastewater during the slurry treatment process. Brief Description of the Drawings

[0046] Figure 1 It is a schematic structural diagram of the recovery device for the high-benefit utilization process of wet-process phosphoric acid slurry provided by the present invention.

[0047] Reference Signs:

[0048] 1. Slurry collection tank; 2. Slurry agitator; 3. Slurry pump; 4. Filter press; 5. Concentrated phosphoric acid buffer tank; 6. Concentrated phosphoric acid pipeline; 7. Dilute phosphoric acid pipeline; 8. Dilute phosphoric acid buffer tank; 9. Filter cloth flushing pipeline; 10. Filter cloth flushing water tank; 11. Filter cloth flushing pump; 12. Flushing liquid pipeline; 13. Flushing liquid collection tank; 14. Flushing liquid agitator; 15. Washing water pump. Detailed Embodiments

[0049] The preferred embodiments of the present invention will be described in more detail below with reference to the drawings. Although the preferred embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to convey the scope of the present invention fully to those skilled in the art.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used in the description of the present invention herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The singular forms "a", "said", and "the" as used in the present invention and the appended claims are also intended to include the plural forms unless the context clearly dictates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0051] It should be understood that although the terms "first", "second", "third", etc. may be used herein to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other.

[0052] The reagents, methods, and equipment used in the present invention, unless otherwise specified, are conventional reagents, methods, and equipment in this technical field.

[0053] The equipment used in the following examples and comparative examples is as follows:

[0054] Vertical filter press: Model: HDLY-III-108; Specification: 7100*5200*4600mm; Jiangsu Xinhongda (Group) Co., Ltd.

[0055] Slurry pump: Model: 125WD-400; Q = 200m3 / h, H = 70m, P = 132KW, n = 1450rpm; Chengdu Yongyi Pump Industry Co., Ltd.

[0056] Filter cloth washing pump: Model: CDMF65-60FSWLC; Q = 65m3 / h, H = 124m, P = 37KW, n = 2900rpm; Nanfang Pump Industry Co., Ltd.

[0057] Example 1

[0058] High-benefit utilization process recovery device for wet-process phosphoric acid slurry

[0059] It includes a slurry collection tank 1, a slurry agitator 2, a slurry pump 3, a filter press 4, a concentrated phosphoric acid pipeline 6, a concentrated phosphoric acid buffer tank 5, a dilute phosphoric acid pipeline 7, a dilute phosphoric acid buffer tank 8, a filter cloth washing pipeline 9, a filter cloth washing water tank 10, a filter cloth washing pump 11, a washing liquid pipeline 12, and a washing liquid collection tank 13;

[0060] The slurry agitator 2 is arranged in the slurry collection tank 1. The inlet end of the slurry pump 3 is connected to the bottom of the slurry collection tank 1 through a pipeline, and the outlet end of the slurry pump 3 is connected to the filter press 4 through a pipeline;

[0061] The concentrated phosphoric acid pipeline 6 connects the filter press 4 and the concentrated phosphoric acid buffer tank 5, the dilute phosphoric acid pipeline 7 connects the filter press 4 and the dilute phosphoric acid buffer tank 8, and the filter cloth washing pipeline 9 connects the filter press 4 and the filter cloth washing water tank 10; the washing liquid collection tank 13 is connected to the filter press 4 through the washing liquid pipeline 12;

[0062] The inlet end of the filter cloth washing pump 11 is connected to the bottom of the filter cloth washing water tank 10 through a pipeline, and the outlet end of the filter cloth washing pump 11 is connected to the filter press 4 through a pipeline.

[0063] The washing liquid collection tank 13 is provided with a washing liquid stirrer 14, and the bottom of the washing liquid collection tank 13 is connected to the washing water pump 15.

[0064] The filter press 4 is a vertical filter press;

[0065] The filter pressing pressure of the filter press 4 is 12 MPa.

[0066] The slurry pump 3 is a high-lift slurry pump, and the head of the slurry pump is 70 m.

[0067] The filter cloth washing pump 11 is a high-lift washing pump, and the head of the filter cloth washing pump is 70 m.

[0068] The concentrated phosphoric acid buffer tank 5 and the dilute phosphoric acid buffer tank 8 are respectively connected to the concentrated phosphoric acid tank and the dilute phosphoric acid tank through a transfer pump, and the washing liquid collection tank 13 is connected to the workshop washing water tank through a washing water pump.

[0069] Example 2

[0070] Using the high-benefit utilization process recovery device for wet-process phosphoric acid slurry in Example 1, the concentrated phosphoric acid slurry is treated:

[0071] S1. Stir the concentrated phosphoric acid slurry in the slurry collection tank evenly, and transport the concentrated phosphoric acid slurry to the filter press through the slurry pump for primary filtration. The concentrated phosphoric acid obtained after filtration is transported to the concentrated phosphoric acid buffer tank through the concentrated phosphoric acid pipeline for the production of high-benefit phosphoric acid products;

[0072] S2. After the primary filtration is completed, continuously introduce washing water into the filter press for secondary filtration for 240 s; within the first 120 s of the secondary filtration, the dilute phosphoric acid obtained after washing enters the dilute phosphoric acid buffer tank through the dilute phosphoric acid pipeline; at this time, close the regulating valve on the concentrated phosphoric acid pipeline and open the regulating valve on the dilute phosphoric acid pipeline to transport the dilute phosphoric acid to the dilute phosphoric acid buffer tank;

[0073] S3. Within the remaining 120 s of the secondary filtration, the filter cloth washing water obtained by washing enters the filter cloth washing water tank through the filter cloth washing pipeline; at this time, close the regulating valve on the dilute phosphoric acid pipeline and open the regulating valve on the filter cloth washing pipeline to transport the filter cloth washing water to the filter cloth washing water tank;

[0074] S4. After secondary pressure filtration, unload the filter residue gypsum, and use the filter cloth washing water in the filter cloth washing water tank to wash the filter cloth of the pressure filter through the filter cloth washing pump. The washing liquid after washing enters the washing liquid collection tank through the washing liquid pipeline;

[0075] The pressure of the first pressure filtration is 12 MPa; the pressure of the second pressure filtration is 12 MPa; the duration of the first pressure filtration is 150 s; the flow rate of the washing water is 38 m 3 / h.

[0076] Example 3

[0077] Adopt the recovery device for the high-benefit utilization process of wet-process phosphoric acid slurry in Example 1 to treat the concentrated phosphoric acid slurry:

[0078] S1. Stir the concentrated phosphoric acid slurry in the slurry collection tank evenly, and transport the concentrated phosphoric acid slurry to the pressure filter through the slurry pump for the first pressure filtration. The concentrated phosphoric acid obtained after pressure filtration is transported to the concentrated phosphoric acid buffer tank through the concentrated phosphoric acid pipeline for the production of high-benefit phosphoric acid products;

[0079] S2. After the first pressure filtration is completed, continuously introduce washing water into the pressure filter for 200 s of secondary pressure filtration; within the first 100 s of secondary pressure filtration, the dilute phosphoric acid obtained after washing enters the dilute phosphoric acid buffer tank through the dilute phosphoric acid pipeline; at this time, close the regulating valve on the concentrated phosphoric acid pipeline and open the regulating valve on the dilute phosphoric acid pipeline to transport the dilute phosphoric acid to the dilute phosphoric acid buffer tank;

[0080] S3. Within the remaining 100 s of secondary pressure filtration, the filter cloth washing water obtained by washing enters the filter cloth washing water tank through the filter cloth washing pipeline; at this time, close the regulating valve on the dilute phosphoric acid pipeline and open the regulating valve on the filter cloth washing pipeline to transport the filter cloth washing water to the filter cloth washing water tank;

[0081] S4. After secondary pressure filtration, unload the filter residue gypsum, and use the filter cloth washing water in the filter cloth washing water tank to wash the filter cloth of the pressure filter through the filter cloth washing pump. The washing liquid after washing enters the washing liquid collection tank through the washing liquid pipeline;

[0082] The pressure of the first pressure filtration is 12 MPa; the pressure of the second pressure filtration is 12 MPa; the duration of the first pressure filtration is 120 s; the flow rate of the washing water is 30 m 3 / h.

[0083] Example 4

[0084] Adopt the recovery device for the high-benefit utilization process of wet-process phosphoric acid slurry in Example 1 to treat the concentrated phosphoric acid slurry:

[0085] S1. Stir the concentrated phosphoric acid slurry in the slurry collection tank evenly, and transport the concentrated phosphoric acid slurry to a filter press through a slurry pump for primary filtration. Transport the concentrated phosphoric acid obtained after filtration to the concentrated phosphoric acid buffer tank through a concentrated phosphoric acid pipeline for producing high-benefit phosphoric acid products;

[0086] S2. After the primary filtration is completed, continuously introduce washing water into the filter press for secondary filtration for 300 s. Within the first 140 s of the secondary filtration, the dilute phosphoric acid obtained after washing enters the dilute phosphoric acid buffer tank through a dilute phosphoric acid pipeline. At this time, close the regulating valve on the concentrated phosphoric acid pipeline and open the regulating valve on the dilute phosphoric acid pipeline to transport the dilute phosphoric acid to the dilute phosphoric acid buffer tank;

[0087] S3. During the remaining time of the secondary filtration, the filter cloth washing water obtained from washing enters the filter cloth washing water tank through a filter cloth washing pipeline. At this time, close the regulating valve on the dilute phosphoric acid pipeline and open the regulating valve on the filter cloth washing pipeline to transport the filter cloth washing water to the filter cloth washing water tank;

[0088] S4. After the secondary filtration, unload the filter residue gypsum, and use the filter cloth washing water in the filter cloth washing water tank from a filter cloth washing pump to wash the filter cloth of the filter press. The washing liquid after washing enters the washing liquid collection tank through a washing liquid pipeline;

[0089] The pressure of the primary filtration is 12 MPa; the pressure of the secondary filtration is 12 MPa; the duration of the primary filtration is 180 s; the flow rate of the washing water is 45 m 3 / h.

[0090] Comparative Example 1

[0091] Use the high-benefit utilization process recovery device for wet-process phosphoric acid slurry in Example 1 to treat the concentrated phosphoric acid slurry:

[0092] S1. Stir the concentrated phosphoric acid slurry in the slurry collection tank evenly, and transport the concentrated phosphoric acid slurry to a filter press through a slurry pump for primary filtration. Transport the concentrated phosphoric acid obtained after filtration to the concentrated phosphoric acid buffer tank through a concentrated phosphoric acid pipeline for producing high-benefit phosphoric acid products;

[0093] S2. After the primary filtration is completed, continuously introduce washing water into the filter press for secondary filtration for 240 s. The phosphoric acid obtained after washing enters the dilute phosphoric acid buffer tank through a dilute phosphoric acid pipeline. Only open the regulating valve on the dilute phosphoric acid pipeline to transport the phosphoric acid to the dilute phosphoric acid buffer tank;

[0094] S3. After the secondary filtration, unload the filter residue gypsum, introduce clean water to wash the filter cloth of the filter press, and the washing liquid after washing enters the washing liquid collection tank through a washing liquid pipeline;

[0095] The pressure for the first filtration is 12 MPa; the pressure for the second filtration is 12 MPa; the duration of the first filtration is 150 s; the flow rate of the washing water is 38 m 3 / h..

[0096] Comparative Example 2

[0097] Using the high-efficiency utilization process recovery device for wet-process phosphoric acid slurry in Example 1, the concentrated phosphoric acid slurry was treated as follows:

[0098] S1. Stir the concentrated phosphoric acid slurry in the slurry collection tank evenly, and use a slurry pump to transport the concentrated phosphoric acid slurry to a filter press for direct second filtration. Continuously introduce washing water into the filter press for 240 s of second filtration; within the first 120 s of the second filtration, the dilute phosphoric acid obtained after washing enters the dilute phosphoric acid buffer tank through the dilute phosphoric acid pipeline; at this time, close the regulating valve on the concentrated phosphoric acid pipeline and open the regulating valve on the dilute phosphoric acid pipeline to transport the dilute phosphoric acid to the dilute phosphoric acid buffer tank;

[0099] S3. Within the remaining 120 s of the second filtration, the filter cloth flushing water obtained from washing enters the filter cloth flushing water tank through the filter cloth flushing pipeline; at this time, close the regulating valve on the dilute phosphoric acid pipeline and open the regulating valve on the filter cloth flushing pipeline to transport the filter cloth flushing water to the filter cloth flushing water tank;

[0100] S4. After the second filtration, unload the filter residue gypsum, and use the filter cloth flushing water in the filter cloth flushing water tank from a filter cloth flushing pump to flush the filter cloth of the filter press. The flushing liquid after flushing enters the flushing liquid collection tank through the flushing liquid pipeline;

[0101] The pressure for the first filtration is 12 MPa; the pressure for the second filtration is 12 MPa; the duration of the first filtration is 150 s; the flow rate of the washing water is 38 m 3 / h.

[0102] Comparative Example 3

[0103] Basically the same as Example 1, the difference from Example 1 is that:

[0104] S2. Conduct second filtration for 150 s; within the first 70 s of the second filtration, the dilute phosphoric acid obtained after washing enters the dilute phosphoric acid buffer tank through the dilute phosphoric acid pipeline;

[0105] S3. Within the remaining 80 s of the second filtration, the filter cloth flushing water obtained from washing enters the filter cloth flushing water tank through the filter cloth flushing pipeline;

[0106] Comparative Example 4

[0107] Basically the same as Example 1, the difference from Example 1 is that:

[0108] S2. Conduct secondary pressure filtration for 400 s; within the first 200 s of secondary pressure filtration, the dilute phosphoric acid obtained after washing enters the dilute phosphoric acid buffer tank through the dilute phosphoric acid pipeline;

[0109] S3. Within the remaining 200 s of secondary pressure filtration, the filter cloth flushing water obtained from washing enters the filter cloth flushing water tank through the filter cloth flushing pipeline;

[0110] Comparative Example 5

[0111] It is basically the same as Example 1, and the difference from Example 1 is that:

[0112] The duration of primary pressure filtration is 90 s; the flow rate of the washing water is 25 m 3 / h.

[0113] Comparative Example 6

[0114] It is basically the same as Example 1, and the difference from Example 1 is that:

[0115] The duration of primary pressure filtration is 210 s; the flow rate of the washing water is 50 m 3 / h.

[0116] The above-mentioned examples and comparative examples all passed the following performance tests:

[0117] 1. Solids content test: HG / T 4068-2022 Test method for industrial wet-process crude phosphoric acid; test the concentrated phosphoric acid slurry, the solution in the concentrated phosphoric acid buffer tank, and the solution in the dilute phosphoric acid buffer tank;

[0118] 2. P2O5 content test: HG / T 4068-2022 Test method for industrial wet-process crude phosphoric acid; test the concentrated phosphoric acid slurry, the solution in the concentrated phosphoric acid buffer tank, the solution in the dilute phosphoric acid buffer tank, the solution in the filter cloth flushing water tank, and the solution in the flushing liquid collection tank;

[0119] 3. P2O5 content test of the filter residue gypsum: JC / T 2073-2011 Standard test method for the determination of phosphorus and fluorine in phosphogypsum

[0120] Table 1 Data of examples and comparative examples

[0121]

[0122] In Comparative Example 1, the washing water was not recycled in batches, the P2O5 content of the dilute phosphoric acid was relatively low, more water was wasted, but the P2O5 content of the subsequent flushing liquid did not decrease significantly, and the P2O5 content of the filter residue gypsum did not decrease significantly either;

[0123] In Comparative Example 2, primary filtration was not carried out. Subsequently, the P2O5 content and solid content of the dilute phosphoric acid increased significantly. The P2O5 content of the filter cloth washing water and the washing liquid was relatively high, and it was difficult to reuse the washing liquid. Moreover, the P2O5 content of the filter residue gypsum was relatively high.

[0124] In Comparative Example 3, the secondary filtration time was too short. Subsequently, the P2O5 content of the dilute phosphoric acid increased. The P2O5 content of the filter cloth washing water and the washing liquid was relatively high, and it was difficult to reuse the washing liquid. Moreover, the P2O5 content of the filter residue gypsum was relatively high.

[0125] In Comparative Example 4, the secondary filtration time was too long, and the effect was not significantly improved, resulting in a waste of water resources.

[0126] In Comparative Example 5, the primary filtration time was short and the flow rate of the washing water was small. Subsequently, the P2O5 content and solid content of the dilute phosphoric acid increased significantly. The P2O5 content of the filter cloth washing water and the washing liquid was relatively high, and it was difficult to reuse the washing liquid. Moreover, the P2O5 content of the filter residue gypsum was relatively high.

[0127] In Comparative Example 6, the primary filtration time was long and the flow rate of the washing water was large, but the effect was not significantly improved, resulting in a waste of resources.

[0128] In the above embodiments, the descriptions of the respective embodiments have their own focuses. For the parts not described in detail in a certain embodiment, reference may be made to the relevant descriptions of other embodiments. The above has described the embodiments of the present application. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art in the technical field without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technologies in the market, or to enable other ordinary technical personnel in the technical field to understand the embodiments disclosed herein.

Claims

1. A process for the highly efficient utilization of wet-process phosphoric acid slurry, characterized in that, It includes the following steps: S1. Stir the concentrated phosphoric acid slurry in the slurry collection tank evenly, and transport the concentrated phosphoric acid slurry to a filter press through a slurry pump for primary filtration. The concentrated phosphoric acid obtained after filtration is transported to the concentrated phosphoric acid buffer tank through a concentrated phosphoric acid pipeline; S2. After the primary filtration is completed, continuously introduce washing water into the filter press for secondary filtration for 200 - 300 s; within 100 - 140 s before the secondary filtration, the dilute phosphoric acid obtained after washing enters the dilute phosphoric acid buffer tank through a dilute phosphoric acid pipeline; close the regulating valve on the concentrated phosphoric acid pipeline, open the regulating valve on the dilute phosphoric acid pipeline, and transport the dilute phosphoric acid to the dilute phosphoric acid buffer tank; S3. During the remaining time of the secondary filtration, the filter cloth washing water obtained from washing enters the filter cloth washing water tank through a filter cloth washing pipeline; close the regulating valve on the dilute phosphoric acid pipeline, open the regulating valve on the filter cloth washing pipeline, and transport the filter cloth washing water to the filter cloth washing water tank; S4. After the secondary filtration, unload the filter residue gypsum, and use the filter cloth washing water in the filter cloth washing water tank from the filter cloth washing pump to wash the filter cloth of the filter press. The washing liquid after washing enters the washing liquid collection tank through a washing liquid pipeline; The solid content of the concentrated phosphoric acid slurry is 3 - 10%; the P2O5 content in the concentrated phosphoric acid slurry is 38 - 43%; The filtration pressure of the filter press is 10 - 16 MPa; The slurry pump is a high-lift slurry pump, and the lift of the slurry pump ≥ 70 m.

2. The high-efficiency utilization process of wet-process phosphoric acid slurry according to claim 1, characterized in that: The filter press is a vertical filter press or a horizontal filter press.

3. The high-efficiency utilization process of wet-process phosphoric acid slurry according to claim 1, characterized in that: The filter cloth washing pump is a high-lift washing pump, and the lift of the filter cloth washing pump ≥ 70 m.

4. The high-efficiency utilization process of wet-process phosphoric acid slurry according to claim 1, characterized in that: The flow rate of the washing water is 30 - 45 m 3 / h.

5. A high-efficiency utilization recovery device for wet-process phosphoric acid slurry used in the high-efficiency utilization process of wet-process phosphoric acid slurry according to any one of claims 1 - 4, characterized in that: It includes a slurry collection tank, a slurry stirrer, a slurry pump, a filter press, a concentrated phosphoric acid pipeline, a concentrated phosphoric acid buffer tank, a dilute phosphoric acid pipeline, a dilute phosphoric acid buffer tank, a filter cloth washing pipeline, a filter cloth washing water tank, a filter cloth washing pump, a washing liquid pipeline, and a washing liquid collection tank; The slurry stirrer is arranged in the slurry collection tank. The inlet end of the slurry pump is connected to the bottom of the slurry collection tank through a pipeline, and the outlet end of the slurry pump is connected to the filter press through a pipeline; The concentrated phosphoric acid pipeline connects the filter press and the concentrated phosphoric acid buffer tank. The dilute phosphoric acid pipeline connects the filter press and the dilute phosphoric acid buffer tank. The filter cloth washing pipeline connects the filter press and the filter cloth washing water tank; the washing liquid collection tank is connected to the filter press through a washing liquid pipeline; The inlet end of the filter cloth washing pump is connected to the bottom of the filter cloth washing water tank through a pipeline, and the outlet end of the filter cloth washing pump is connected to the filter press through a pipeline; The washing liquid collection tank is provided with a washing liquid stirrer, and the bottom of the washing liquid collection tank is connected to a washing water pump.

6. The high-efficiency utilization recovery device for wet-process phosphoric acid slurry according to claim 5, characterized in that: The filter press is a vertical filter press or a horizontal filter press.

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