Method for efficiently purifying and recycling phosphorus resources from raffinate acid

Abstract

The application discloses a method for efficiently purifying and recycling phosphorus resources from raffinate acid. The method comprises the following steps: S1, transporting the raffinate acid generated in the wet purification phosphoric acid extraction section to a mixed filter acid tank; S2, transporting the slurry of a dilute phosphoric acid clarifying tank and / or the thick slurry of a disc flushing water tank to the mixed filter acid tank, and mixing the slurry and / or the thick slurry with the raffinate acid to form mixed filter acid; S3, stirring and mixing the mixed filter acid to uniformly mix the slurry of the dilute phosphoric acid clarifying tank and / or the thick slurry of the disc flushing water tank with the raffinate acid; S4, transporting the mixed mixed filter acid to a filter device for solid-liquid separation treatment, to obtain filter residue and filter clear acid; S5, transporting the filter residue to a general fertilizer product production device for utilization; and S6, transporting the filter clear acid to a concentration system for concentration treatment, and transporting the concentrated filter clear acid to a high-end phosphorus product production device for utilization.

Description

Technical Field

[0001] This application relates to the field of phosphating technology, and in particular to a method for efficiently purifying and recovering phosphorus resources from residual raffinate. Background Technology

[0002] This invention belongs to the technical field of resource utilization of waste acid from wet purification of phosphoric acid production, and particularly relates to a method for efficient purification and recovery of phosphoric acid resources from residual acid.

[0003] In the wet-process purification of phosphoric acid, a large amount of raffinate is generated during the extraction stage. As the capacity of wet-process phosphoric acid purification units continues to expand, the amount of raffinate generated continues to increase. Because the raffinate still contains a high concentration of P2O5, typically reaching 42%–45%, and also contains various impurity ions such as magnesium, calcium, and aluminum, as well as a large number of suspended solid particles, it is characterized by high impurity content, fine particles, high viscosity, and poor filtration performance. Direct discharge would not only cause environmental pollution but also lead to a significant waste of phosphorus resources; therefore, the raffinate is usually required for comprehensive recovery and utilization.

[0004] In existing technologies, residual raffinate is typically used directly in the production of low-value-added products, or it is mixed with concentrated phosphoric acid clarification slurry and then purified by pressure filtration. However, in existing mixed pressure filtration processes, due to the small particle size of suspended particles in the residual raffinate and the high viscosity of the slurry, a high proportion of residual raffinate in the mixed system can easily cause filter cloth clogging, leading to a decrease in the pressure filtration rate. This necessitates frequent shutdowns for cleaning and maintenance of the pressure filtration equipment, affecting the operating efficiency of the pressure filtration system and increasing the cost of pressure filtration.

[0005] Furthermore, in existing technologies, when concentrated phosphoric acid clarification slurry is mixed with residual raffinate for pressure filtration, the high phosphorus content of both results in filter residue containing a significant amount of phosphorus. The P2O5 content in the filter residue typically reaches 25%–35%, leading to substantial phosphorus loss and reducing the high-value recovery rate of phosphorus resources. To reduce the phosphorus content in the filter residue, multiple water washing processes are usually required. However, this method not only increases the system's water balance burden but also reduces the concentration of the filtered acid, increasing energy consumption and operating costs in subsequent concentration processes and making the overall process more complex.

[0006] Meanwhile, existing residual acid filtration purification processes have limited capacity for treating residual acid. To ensure stable operation of the filtration process, the proportion of residual acid in the mixed slurry is usually low, resulting in low residual acid utilization efficiency and difficulty in meeting the continuous processing requirements of large-scale wet-process phosphoric acid purification units. In addition, the existing process does not form an effective cascade utilization model for phosphorus resources between the filter residue and the purified acid, and the phosphorus resources in the filter residue are not fully utilized, making it difficult to meet the needs of both ordinary fertilizer production and high-end phosphorus product production.

[0007] Therefore, how to provide a method for efficiently purifying and recovering phosphorus resources from residual acid that can improve the filtration efficiency of residual acid, reduce the phosphorus content of filter residue, reduce filter cloth clogging, improve the absorption capacity of residual acid, and realize the cascade recovery and utilization of phosphorus resources has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0008] To address the aforementioned technical problems, this application provides a method for the efficient purification and recovery of phosphorus resources from residual raffinate.

[0009] The technical solution provided in this application is described below:

[0010] This application provides a method for the efficient purification and recovery of phosphorus resources from residual acid, including: S1. The residual acid produced in the wet purification phosphoric acid extraction section is transported to the mixed pressure filter acid tank. S2. The slurry from the dilute phosphoric acid clarification tank and / or the thick slurry from the rinsing tank are transported to the mixed filter acid tank and mixed with the residual raffinate to form mixed filter acid; wherein the slurry from the dilute phosphoric acid clarification tank and / or the thick slurry from the rinsing tank are added to the residual raffinate at a mass ratio of 30% to 50%. S3. Stir and mix the mixed filter acid to make the slurry of the dilute phosphoric acid clarification tank and / or the thick slurry of the flushing tank evenly mixed with the residual acid. S4. The mixed filter acid is transported to a filter press device for solid-liquid separation to obtain filter residue and filtered acid. S5. The filter residue is transported to a general fertilizer production unit for use; S6. The filtered acid is transported to a concentration system for concentration, and the concentrated filtered acid is then transported to a high-end phosphorus product production unit for use.

[0011] Optionally, the P2O5 content in the residual acid is 42% to 45%.

[0012] Optionally, the P2O5 content in the slurry of the dilute phosphoric acid clarification tank is 24%–28%, and the solid content is 4%–8%.

[0013] Optionally, the P2O5 content in the slurry of the slurry tank is 10% to 15%, and the solid content is 20% to 25%.

[0014] Optionally, in step S3, the mixed filter acid is stirred and mixed using a mechanical stirring method.

[0015] Optionally, in step S4, a plate and frame filter press and / or a vertical filter press are used to perform solid-liquid separation treatment on the mixed filter acid.

[0016] Optionally, the P2O5 content in the filter residue obtained in step S4 is 15% to 28%.

[0017] Optionally, the P2O5 content in the filtered acid obtained in step S4 is 25% to 36%.

[0018] Optionally, in step S6, the filtered acid is concentrated using an evaporation and concentration method.

[0019] Optionally, the mass percentage of residual acid in the mixed filter press acid is 50% to 70%.

[0020] As can be seen from the above technical solutions, this application has the following beneficial effects: 1. This invention involves mixing the slurry from the dilute phosphoric acid clarification tank and / or the thick slurry from the flushing tank with the residual raffinate and then performing pressure filtration. By using a slurry with low phosphorus content and high solids content to adjust the residual raffinate, the phosphorus content in the filter residue can be effectively reduced, the loss of phosphorus resources with the filter residue can be reduced, and the high-value recovery and utilization rate of phosphorus resources in the residual raffinate can be improved.

[0021] 2. This invention improves the rheological properties and filter skeleton structure of the mixed slurry by adding high-solids-content dilute phosphoric acid clarification tank slurry and / or thick slurry from the flushing tank to the residual acid, thereby reducing the viscosity of the mixed slurry, reducing filter cloth clogging, increasing the filtration rate and the operational stability of the filtration device, and thus reducing the frequency of filtration system shutdown for cleaning and equipment maintenance costs.

[0022] 3. By controlling the proportion of slurry from the dilute phosphoric acid clarification tank and / or thick slurry from the flushing tank in the mixed slurry, the mixed filter acid can still have good filtration performance under the condition of a high proportion of residual raffinate, thereby improving the filter absorption capacity of residual raffinate and meeting the continuous processing requirements of large-scale wet purification phosphoric acid units.

[0023] 4. This invention can obtain low-phosphorus filter residue and high-phosphorus filtered acid by a single pressure filtration of mixed filtered acid, without the need for multiple water washing treatments of the filter residue. This can effectively simplify the process, reduce the water balance burden of the system, and reduce energy consumption and operating costs in the subsequent pressure filtration and acid concentration process.

[0024] 5. In this invention, the filter residue obtained by pressure filtration can be directly transported to the ordinary fertilizer production device for use, while the concentrated pressure-filtered acid is transported to the high-end phosphorus product production device for use, thereby realizing the cascade recovery and utilization of phosphorus resources, improving the comprehensive utilization efficiency of phosphorus resources and the added value of products.

[0025] 6. This invention uses slurry from a dilute phosphoric acid clarification tank and thick slurry from a flushing tank as slurry conditioning media, which can realize the synergistic resource utilization of by-product slurries within the wet purification phosphoric acid system, reduce the amount of waste slurry discharged, and improve the overall resource utilization rate and green production level of the system. Attached Figure Description

[0026] Figure 1 This is a schematic flowchart of the first embodiment of the method for efficient purification and recovery of phosphorus resources from residual acid provided in this application. Figure 2 This is a schematic flowchart of the second embodiment of the method for efficient purification and recovery of phosphorus resources from residual acid provided in this application. Figure 3 This is a schematic flowchart of the third embodiment of the method for efficient purification and recovery of phosphorus resources from residual acid provided in this application. Detailed Implementation

[0027] In this application, the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and other terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to describe the relative positional relationship between the components or parts and do not specifically limit the specific installation orientation of each component or part.

[0028] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0029] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; 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, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0030] Furthermore, the structures, proportions, sizes, etc., drawn in the accompanying drawings of this application are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modification to the structure, change in the proportional relationship, or adjustment of the size, without affecting the effects and purposes that this application can produce, should still fall within the scope of the technical content disclosed in this application.

[0031] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] Example 1: See Figure 1 This application first provides an embodiment of a method for the efficient purification and recovery of phosphorus resources from residual raffinate, the embodiment including: This embodiment provides a method for the efficient purification and recovery of phosphorus resources from residual raffinate, which is used to purify the residual raffinate generated in the extraction section of the wet purification phosphoric acid production process and to recycle and utilize phosphorus resources in stages, so as to improve the resource utilization efficiency of residual raffinate and reduce the operating cost of the pressure filtration process.

[0033] The method provided in this embodiment includes the following steps: S1. The residual acid produced in the wet purification phosphoric acid extraction section is transported to the mixing and filtration acid tank.

[0034] In this embodiment, the P2O5 content in the residual acid is 42%–45%, and it contains impurities such as magnesium ions, calcium ions, aluminum ions, and suspended solid particles. Because the residual acid has high viscosity, small suspended particle size, and poor filtration performance, it is difficult to directly perform high-efficiency pressure filtration.

[0035] S2. The slurry from the dilute phosphoric acid clarification tank and / or the thick slurry from the flushing tank are transported to the mixed filter acid tank and mixed with the residual leaching acid to form mixed filter acid.

[0036] The slurry from the dilute phosphoric acid clarification tank and / or the thick slurry from the rinsing tank are added to the residual acid at a mass ratio of 30% to 50%.

[0037] In this embodiment, the slurry in the dilute phosphoric acid clarification tank is the bottom slurry formed after dilute phosphoric acid has been clarified and settled, with a P2O5 content of 24% to 28% and a solid content of 4% to 8%; the slurry in the flushing water tank is the slurry formed by collecting flushing water from the rotary filter of the phosphoric acid unit, with a P2O5 content of 10% to 15% and a solid content of 20% to 25%.

[0038] By adding low-phosphorus, high-solids dilute phosphoric acid slurry from the clarification tank and / or thick slurry from the flushing tank to the residual slurry, the rheological properties of the mixed slurry can be effectively improved, the viscosity of the slurry can be reduced, and the slurry filter skeleton structure can be improved, thereby reducing the filtration resistance in the subsequent pressure filtration process.

[0039] In this embodiment, the mass percentage of residual raffinate in the mixed filter press acid is 50% to 70%. This ensures a high-value recovery rate of phosphorus resources while improving the filter press utilization capacity of residual raffinate.

[0040] S3. Stir and mix the mixed filter acid to make the slurry from the dilute phosphoric acid clarification tank and / or the thick slurry from the flushing tank uniformly mixed with the residual acid.

[0041] In this embodiment, mechanical stirring is used to mix the mixed filter acid in step S3. Specifically, one or more of a paddle stirrer, impeller stirrer, or frame stirrer can be used to continuously stir the mixed filter acid to prevent solid particles from settling and to improve the mixing uniformity between the components.

[0042] Mechanical stirring allows low-phosphorus slurry to come into full contact with residual acid, thereby improving the flowability and filtration performance of the mixed slurry, reducing cloth clogging caused by uneven local concentration of the slurry, and improving the solid-liquid separation efficiency in the subsequent pressure filtration process.

[0043] S4. The mixed filter acid is transported to a filter press device for solid-liquid separation to obtain filter residue and filter acid.

[0044] In this embodiment, in step S4, a plate and frame filter press and / or a vertical filter press are used to perform solid-liquid separation treatment on the mixed filter acid.

[0045] The plate and frame filter press uses the filtration chamber formed between the filter plates and the filter frame to filter the mixed filtration acid, which has the characteristics of high filtration accuracy and good filtrate clarification effect; the vertical filter press realizes continuous or semi-continuous filtration through the vertical filtration structure, which has the characteristics of high automation and large processing capacity.

[0046] In this embodiment, the P2O5 content in the filter cake obtained in step S4 is 15% to 28%. Because a low-phosphorus slurry is added to the mixed slurry, the phosphorus content in the filter cake is effectively reduced, minimizing phosphorus loss. Simultaneously, the resulting filter cake has a relatively loose structure, making it less prone to adhering to the filter cloth surface, thus reducing the risk of filter cloth clogging and the frequency of downtime for cleaning the filter press.

[0047] In this embodiment, the P2O5 content in the filtered acid obtained in step S4 is 25% to 36%. Since a large amount of phosphorus resources are enriched in the filtered acid, it is beneficial for the subsequent production of high-value phosphorus products.

[0048] S5. The filter residue is transported to the general fertilizer production unit for use.

[0049] In this embodiment, since the P2O5 content in the filter residue is 15% to 28%, the filter residue can be directly used as a raw material for the production of general fertilizer products for comprehensive utilization without the need for multiple water washing treatments, thereby reducing the water balance burden of the system and lowering the operating cost of the filter press.

[0050] S6. The filtered acid is transported to a concentration system for concentration, and the concentrated filtered acid is then transported to a high-end phosphorus product production unit for use.

[0051] In this embodiment, step S6 uses evaporation to concentrate the filtered acid. Specifically, vacuum evaporation, multi-effect evaporation, or forced circulation evaporation can be used to concentrate the filtered acid, thereby increasing the P2O5 concentration in the filtered acid.

[0052] The concentrated filtered acid can be transported to high-end phosphorus product production facilities to produce industrial-grade phosphoric acid, electronic-grade phosphoric acid, or other high-value-added phosphorus products, thereby improving the high-value utilization rate of phosphorus resources.

[0053] This embodiment effectively improves the problems of high viscosity, easy clogging, and low filtration efficiency that exist when directly filtration of residual acid by using a mixture of low-phosphorus, high-solids-content dilute phosphoric acid clarification tank slurry and / or flushing tank thick slurry with residual acid for pressure filtration. Simultaneously, phosphorus resources can be enriched into the filtered acid through a single pressure filtration process, and the phosphorus content in the filter residue can be reduced, thereby achieving cascade recovery and utilization of phosphorus resources, improving the resource utilization efficiency of residual acid, and reducing system operating costs.

[0054] Example 2: See Figure 2 This embodiment provides a method for efficient purification and recovery of phosphorus resources using residual raffinate, which is basically the same as that in Embodiment 1. The difference is that in this embodiment, the slurry from the dilute phosphoric acid clarification tank is mixed with the residual raffinate for pressure filtration.

[0055] Specifically, this embodiment includes the following steps: A1. The residual acid produced in the wet purification phosphoric acid extraction section is transported to the mixing and filtration acid tank.

[0056] In this embodiment, the P2O5 content in the residual acid is 43%.

[0057] A2. The slurry from the dilute phosphoric acid clarification tank is transported to the mixed filter acid tank and mixed with the residual raffinate to form mixed filter acid.

[0058] The slurry from the dilute phosphoric acid clarification tank is added to the residual acid at a mass ratio of 40%.

[0059] In this embodiment, the P2O5 content in the slurry from the dilute phosphoric acid clarification tank is 26%, and the solid content is 6%. The mass percentage of the residual raffinate in the mixed filter press acid is 60%.

[0060] A3. The mixed filter acid is continuously stirred and mixed using a mechanical stirring method.

[0061] In this embodiment, an impeller-type mechanical stirrer is used to stir the mixed filter acid, so that the slurry from the dilute phosphoric acid clarification tank and the residual acid are fully and evenly mixed, in order to avoid uneven local concentration of the slurry and sedimentation of solid particles.

[0062] A4. The mixed filter acid is transported to a plate and frame filter press for solid-liquid separation to obtain filter residue and filter acid.

[0063] In this embodiment, the P2O5 content in the filter residue obtained after pressure filtration is 18%, and the P2O5 content in the filtered acid is 33%.

[0064] A5. The filter residue from the pressure filter is transported to the general fertilizer production unit for use as a raw material in general fertilizer production.

[0065] A6. The filtered acid is transported to the evaporation and concentration system for concentration, and the concentrated filtered acid is then transported to the high-end phosphorus product production unit for use.

[0066] Example 3: See Figure 3 This embodiment provides a method for efficient purification and recovery of phosphorus resources using residual raffinate, which is basically the same as that in Embodiment 1. The difference is that in this embodiment, a thick slurry from a slurry tank is mixed with residual raffinate for pressure filtration.

[0067] Specifically, this embodiment includes the following steps: B1. The residual acid produced in the wet purification phosphoric acid extraction section is transported to the mixed pressure filter acid tank.

[0068] In this embodiment, the P2O5 content in the residual acid is 45%.

[0069] B2. The thick slurry from the flushing tank is transported to the mixed filter acid tank and mixed with the residual leaching acid to form mixed filter acid.

[0070] The thick slurry from the slurry tank is added to the residual acid at a mass ratio of 50%.

[0071] In this embodiment, the P2O5 content in the slurry from the rinsing tank is 12%, and the solid content is 22%. The mass percentage of residual acid in the mixed filter press acid is 50%.

[0072] B3. The mixed filter acid is stirred and mixed using a mechanical stirring method.

[0073] In this embodiment, a frame-type mechanical stirrer is used to continuously stir the mixed filter acid to improve the uniformity of the slurry.

[0074] B4. The mixed filter acid is transported to a vertical filter press for solid-liquid separation to obtain filter residue and filtered acid.

[0075] In this embodiment, the P2O5 content in the filter residue obtained after pressure filtration is 15%, and the P2O5 content in the filtered acid is 28%.

[0076] B5. The filter residue from the pressure filter is transported to the general fertilizer production unit for utilization.

[0077] B6. The filtered acid is transported to the evaporation and concentration system for concentration, and the concentrated filtered acid is then transported to the high-end phosphorus product production unit for use.

Claims

1. A method for efficiently purifying and recovering phosphorus resources from residual raffinate, characterized in that, Includes the following steps: S1. The residual acid produced in the wet purification phosphoric acid extraction section is transported to the mixed pressure filter acid tank. S2. The slurry from the dilute phosphoric acid clarification tank and / or the thick slurry from the flushing tank are transported to the mixed filter acid tank and mixed with the residual raffinate to form mixed filter acid. The slurry from the dilute phosphoric acid clarification tank and / or the thick slurry from the rinsing tank are added to the residual raffinate at a mass ratio of 30% to 50%. S3. Stir and mix the mixed filter acid to make the slurry of the dilute phosphoric acid clarification tank and / or the thick slurry of the flushing tank evenly mixed with the residual acid. S4. The mixed filter acid is transported to a filter press device for solid-liquid separation to obtain filter residue and filtered acid. S5. The filter residue is transported to a general fertilizer production unit for use; S6. The filtered acid is transported to a concentration system for concentration, and the concentrated filtered acid is then transported to a high-end phosphorus product production unit for use.

2. The method for efficient purification and recovery of phosphorus resources from residual acid according to claim 1, characterized in that, The P2O5 content in the residual acid is 42% to 45%.

3. The method for efficient purification and recovery of phosphorus resources from residual acid according to claim 1, characterized in that, The P2O5 content in the slurry from the dilute phosphoric acid clarification tank is 24%–28%, and the solid content is 4%–8%.

4. The method for efficient purification and recovery of phosphorus resources from residual acid according to claim 1, characterized in that, The P2O5 content in the slurry of the slurry tank is 10% to 15%, and the solid content is 20% to 25%.

5. The method for efficient purification and recovery of phosphorus resources from residual acid according to claim 1, characterized in that, In step S3, the mixed pressure filter acid is stirred and mixed using mechanical stirring.

6. The method for efficient purification and recovery of phosphorus resources from residual acid according to claim 1, characterized in that, In step S4, a plate and frame filter press and / or a vertical filter press are used to perform solid-liquid separation treatment on the mixed filter acid.

7. The method for efficient purification and recovery of phosphorus resources from residual acid according to claim 1, characterized in that, The P2O5 content in the filter residue obtained in step S4 is 15% to 28%.

8. The method for efficient purification and recovery of phosphorus resources from residual acid according to claim 1, characterized in that, The P2O5 content in the filtered acid obtained in step S4 is 25% to 36%.

9. The method for efficient purification and recovery of phosphorus resources from residual acid according to claim 1, characterized in that, In step S6, the filtered acid is concentrated using an evaporation and concentration method.

10. The method for efficient purification and recovery of phosphorus resources from residual acid according to claim 1, characterized in that, The mass percentage of residual acid in the mixed filter press acid is 50% to 70%.

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