Semi-hydrated phosphogypsum purification system and semi-hydrated wet-process phosphoric acid production system

Abstract

The utility model belongs to the technical field of phosphorus chemical industry, and particularly relates to a semi-hydrated phosphogypsum purification system and a semi-hydrated wet-process phosphoric acid production system, which can be used for purifying wet-process phosphoric acid semi-hydrated phosphogypsum. The purification system comprises a reactor, flotation devices, gravity separation devices, a high-frequency screen and a filter pressing module, the reactor is provided with a semi-hydrated phosphogypsum inlet and a water inlet, the reactor is connected with N flotation devices connected in series, M gravity separation devices connected in series are connected behind the flotation devices, the gravity separation devices are all connected with the high-frequency screen, and the high-frequency screen is connected with the filter pressing module; n is an integer greater than or equal to 2, and M is an integer greater than or equal to 2. Impurities such as phosphorus, fluorine and siliceous are effectively separated from semi-hydrated phosphogypsum in the reactor, and flotation, gravity separation, high-frequency screening and filter pressing washing are combined for impurity removal, so that the impurities can be effectively removed, and the phosphogypsum with relatively high purity is obtained; meanwhile, the stages of flotation and gravity separation can be selected according to downstream application scenes, the purification yield, cost and purity are balanced, and the application range and field of phosphogypsum are widened.

Description

Technical Field

[0001] The utility model relates to the technical field of phosphorus chemical industry, in particular to a semi-aqueous phosphogypsum purification system and a semi-aqueous wet-process phosphoric acid production system. Background Art

[0002] Phosphogypsum is a solid waste generated during the wet-process phosphoric acid production process. Its primary component is calcium sulfate. Depending on the wet-process phosphoric acid production process, different phosphogypsum contents, including hemihydrate and dihydrate, are produced. For every ton of P₂O₅ produced, 5-5.5 tons of dry-weight phosphogypsum are generated.

[0003] In addition to its primary component, calcium sulfate, phosphogypsum also contains small amounts of impurities such as phosphorus, fluorine, silica, and organic matter. These toxic and harmful impurities leach out during storage, causing varying degrees of environmental pollution. Even though a variety of downstream applications have been developed, such as gypsum powder and gypsum products, sulfuric acid, and cement, these impurities in phosphogypsum can affect processing and the quality of downstream products.

[0004] Therefore, purification and impurity removal of phosphogypsum is the foundation and key to its resource utilization. Currently, phosphogypsum purification systems primarily use flotation to remove organic matter and silica, and water washing to recover soluble substances such as phosphorus and fluorine. However, issues such as incomplete impurity removal still exist.

[0005] In summary, this field still needs a semi-hydrated phosphogypsum purification system with high impurity removal efficiency, which can be combined with relevant process routes to obtain phosphogypsum with higher purity. Utility Model Content

[0006] The purpose of the utility model is to provide a semi-hydrated phosphogypsum purification system and a semi-hydrated wet-process phosphoric acid production system; the system can be used for the purification of wet-process phosphoric acid semi-hydrated phosphogypsum, can effectively remove impurities contained in the semi-hydrated phosphogypsum, and can adjustably balance the purity and yield of calcium sulfate.

[0007] In order to achieve the above-mentioned purpose, the semi-hydrated phosphogypsum purification system described in the present application includes a reactor, a flotation device, a gravity separation device, a high-frequency screen and a filter press module, wherein the reactor is provided with a semi-hydrated phosphogypsum inlet and a water inlet, the reactor is connected to N flotation devices connected in series, and the Nth flotation device is connected to M gravity separation devices in series, and the M gravity separation devices are all connected to the high-frequency screen, and the high-frequency screen is connected to the filter press module; N is an integer ≥2, and M is an integer ≥2.

[0008] The reactor receives hemihydrated phosphogypsum and forms a slurry. Rapid hydration occurs within the reactor, separating the phosphoric acid, organic matter, and black residue from the phosphogypsum, facilitating subsequent flotation and gravity separation. During the flotation process, the slurry is removed from the upper portion of the flotation unit and introduced into the slurry tank, yielding phosphogypsum at the lower portion of the unit. The phosphogypsum obtained after flotation enters the gravity separation unit. The density difference between the phosphogypsum and silicon slag separates the slurry at the bottom and introduces it into the slurry tank. The phosphogypsum obtained from the upper portion of the gravity separation unit then enters a high-frequency screen. The high-frequency screen further removes the slurry from the phosphogypsum, which is then filtered and washed in a filter press module to produce purified phosphogypsum.

[0009] In one set of embodiments, the reactor is connected to the upper inlet of the first flotation device, the lower outlet of the previous flotation device is connected to the upper inlet of the next flotation device, the material is passed between the two flotation columns connected in series by relying on the potential difference, the lower outlet of the Nth flotation device is connected to the upper inlet of the first gravity separation device; the lower outlet of the previous gravity separation device is connected to the upper inlet of the next gravity separation device, and the upper outlets of the M gravity separation devices are all connected to the high-frequency screen inlet.

[0010] In one set of embodiments, the upper outlets of N flotation devices are connected to the slurry tank, the lower outlet of the Mth gravity separation device is connected to the slurry tank, and the upper outlet of the high-frequency screen is connected to the slurry tank.

[0011] In one set of embodiments, the flotation device is a flotation column.

[0012] In one set of embodiments, the gravity separation device is a cyclone.

[0013] In one set of embodiments, the reactor is connected to the first flotation device via an emulsification pump and a feed pump.

[0014] In one set of embodiments, the Nth flotation device is connected to the first gravity separation device via a feed pump.

[0015] In one set of embodiments, the lower outlet of the previous gravity separation device is connected to the feed trough, and then connected to the upper inlet of the next gravity separation device through a feed pump.

[0016] In one embodiment, the filter press module includes a filter press, a raw water tank connected to the filter press inlet, a compressed air storage tank, and a press water tank, and a wash water tank and a filtrate tank connected to the filter press outlet. The lower outlet of the high-frequency screen is connected to the filter press inlet via a concentrate tank.

[0017] In one set of embodiments, the concentrate tank is connected to the filter press inlet through a concentrate pump, the wash water tank is connected to the filter press inlet through a wash water pump, and the squeeze water tank is connected to the filter press inlet through a squeeze water pump.

[0018] In one set of embodiments, the hemihydrate phosphogypsum purification system further includes a water storage tank, wherein the water storage tank is connected to the water inlet of the reactor, and the washing water tank is connected to the water storage tank.

[0019] In one set of embodiments, the water storage tank is connected to the water inlet of the reactor via a water supply pump, and the washing water tank is connected to the water storage tank via a washing water pump.

[0020] In one set of embodiments, the lower outlet of the water storage tank is connected to the water inlet above the reactor, and a hemihydrate phosphogypsum inlet is provided above the reactor.

[0021] In one set of embodiments, the water tank is further provided with a water inlet.

[0022] In one set of embodiments, the washing water tank is connected to an upper inlet of the water storage tank.

[0023] In one set of embodiments, the compressed air storage tank is provided with a compressed air inlet.

[0024] In one group of embodiments, N is 2, 3, 4, 5, 6, 7, 8, 9 or 10; preferably 2, 3, 4, 5.

[0025] In one group of embodiments, M is 2, 3, 4, 5, 6, 7, 8, 9 or 10; preferably 2, 3, 4, 5.

[0026] The present application also provides a semi-aqueous wet-process phosphoric acid production system, which includes the semi-aqueous phosphogypsum purification system described in the present application and a semi-aqueous wet-process phosphoric acid production module, wherein the semi-aqueous phosphogypsum discharge point of the semi-aqueous wet-process phosphoric acid production module is connected to the semi-aqueous phosphogypsum inlet of the reactor.

[0027] The utility model has at least the following beneficial effects:

[0028] (1) The present invention combines unique purification and impurity removal technology to rapidly hydrate the hemihydrate phosphogypsum in a reactor, effectively separating impurities such as phosphorus, fluorine, and silica from the hemihydrate phosphogypsum. Using a combined impurity removal method of flotation, gravity separation, high-frequency screening, and filter press washing, the present invention effectively removes organic matter, silica, phosphorus, fluorine, and other impurities from the hemihydrate phosphogypsum, thereby obtaining phosphogypsum of higher purity. Compared with currently common impurity removal methods, the present invention significantly increases the removal rate of silica and other impurities from phosphogypsum.

[0029] (2) At the same time, the number of flotation and gravity separation stages can be selected according to the downstream application scenarios of phosphogypsum, so as to balance the yield, cost and purity of phosphogypsum purification and expand the application scope and field of phosphogypsum. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1The following is a structural diagram of a specific embodiment of the semi-hydrated phosphogypsum purification system of the present invention.

[0031] Figure numerals: 1-water storage tank, 2-water feed pump, 3-reactor, 4-emulsification pump, 5-first feed pump, 6-first flotation column, 7-second flotation column, 8-second feed pump, 9-slurry tank, 10-feed tank, 11-first cyclone, 12-third feed pump, 13-second cyclone, 14-high frequency screen, 15-fine material tank, 16-compressed air storage tank, 17-wash water pump, 18-pressing water tank, 19-pressing water pump, 20-wash water raw water tank, 21-filtrate tank, 22-washing water pump, 23-washing water tank, 24-fine material pump, 25-filter press. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the utility model for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0033] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "provided with," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0034] The semi-hydrated phosphogypsum purification system described in the present application includes a reactor, a flotation device, a gravity separation device, a high-frequency screen and a filter press module, wherein the reactor is provided with a semi-hydrated phosphogypsum inlet and a water inlet, the reactor is connected to N flotation devices connected in series, the Nth flotation device is connected to M gravity separation devices connected in series, the M gravity separation devices are all connected to the high-frequency screen, and the high-frequency screen is connected to the filter press module; N is an integer ≥2, and M is an integer ≥2.

[0035] Example 1

[0036] Figure 1The invention shows a specific embodiment of the semi-hydrated phosphogypsum purification system described in the present application, comprising a water storage tank 1, a reactor 3, two flotation columns, two cyclones, a high-frequency screen 14, a slurry tank 9 and a filter press module; wherein the lower portion of the water storage tank 1 is connected to the water inlet above the reactor 3 via a water feed pump 2, and a semi-hydrated phosphogypsum inlet is also provided above the reactor 3; the lower portion of the reactor 3 is connected to the upper inlet of the first flotation column 6 via an emulsification pump 4 and a first feed pump 5, the lower outlet of the first flotation column 6 is connected to the upper inlet of the second flotation column 7, and the material is passed by the potential difference, and the lower outlet of the second flotation column 7 is connected to the upper inlet of the first cyclone 11 via a second feed pump 8; the lower outlet of the first cyclone 11 is connected to the feed trough 10, and the feed trough 10 is connected to the upper inlet of the second cyclone 13 via a third feed pump 12; the first cyclone 11, the second The upper outlet of the cyclone 13 is connected to the inlet of the high-frequency screen 14; the upper outlet of the first flotation column 6, the upper outlet of the second flotation column 7, the lower outlet of the second cyclone 13, and the upper outlet of the high-frequency screen 14 are all connected to the slurry tank 9; the lower outlet of the high-frequency screen 14 is connected to the concentrate tank 15, which is connected to the inlet of the filter press 25 via the concentrate pump 24; the raw wash water tank 20 is connected to the inlet of the filter press 25 via the wash water pump 17, and the compressed air storage tank 16 is connected to the inlet of the filter press 25. The compressed air storage tank 16 is provided with a compressed air inlet, and the squeeze water tank 18 is connected to the inlet of the filter press 25 via the squeeze water pump 19; the outlet of the filter press 25 is connected to the filtrate tank 21; the outlet of the filter press 25 is connected to the washing water tank 23, which is connected to the upper inlet of the water storage tank 1 via the washing water pump 22; a water inlet is also provided at the top of the water storage tank 1.

[0037] The washing water tank 23 is connected to the water storage tank 1 to realize the recycling of washing water. The separated slurry is removed from the slurry tank 9 and filtered and washed by the filter press 25 to obtain purified phosphogypsum.

[0038] The specific working process of the hemihydrate phosphogypsum purification system described in this embodiment is as follows.

[0039] Hemihydrated phosphogypsum obtained from the production system, such as that from the hemihydrated wet-process phosphoric acid production module, is introduced into reactor 3 at the discharge point through the hemihydrated phosphogypsum inlet. Water is supplied to reactor 3 from water storage tank 1 via water pump 2, where the hemihydrated phosphogypsum and water mix to form a slurry. Furthermore, the hemihydrated phosphogypsum undergoes a rapid hydration reaction in reactor 3, promoting the dissociation of phosphoric acid, organic matter, and black residue in the hemihydrated phosphogypsum, further facilitating subsequent flotation and gravity separation. The slurry in reactor 3 is introduced into the first flotation column 6 from the upper inlet via an emulsifying pump 4 and a first feed pump 5. The phosphogypsum then flows from the lower outlet of the first flotation column 6 via a differential feed through the upper inlet and into the second flotation column 7. During the flotation process, the organic matter and black residue are introduced into the slurry tank 9 from the upper outlets of the first and second flotation columns 6 and 7. After two stages of flotation, the phosphogypsum flows from the lower outlet of the second flotation column 7 through the second feed pump 8 and the upper inlet into the first cyclone 11. Siliceous black slag and other materials are separated from the phosphogypsum in the cyclone due to density differences. The siliceous black slag and other materials flow from the lower outlet of the first cyclone 11 into the feed trough 10. The black slag and other materials in the feed trough 10 are fed by the third feed pump 12 through the upper inlet into the second cyclone 13 for second-stage cyclonic separation. The black slag and other materials are then introduced into the slurry tank 9 through the lower outlet of the second cyclone 13. The phosphogypsum separated in the first and second cyclones 11 and 13 is discharged from the upper outlet and enters the high-frequency screen 14. After screening by the high-frequency screen 14, the upper slurry is introduced into the slurry tank 9, while the lower phosphogypsum enters the concentrate tank 15. The phosphogypsum in the fine material tank 15 enters the filter press 25 for filtration through the fine material pump 24, the compressed air storage tank 16 introduces compressed air into the filter press 25 for backblowing and angle blowing, and the squeeze water tank 18 introduces squeeze water into the filter press through the squeeze water pump 19. The working principle of squeezing is to separate the solid particles and liquid in the mixture by applying pressure and utilizing the filtering effect of the filter cloth. The squeeze water does not contact the material and can be recycled and stored in the squeeze water tank 18. The filtrate obtained after the phosphogypsum is filtered by the filter press 25 enters the filtrate tank 21, and then the washing water is introduced from the washing water raw water tank 20 through the washing water pump 17 into the filter press 25 to wash the phosphogypsum. The washing water enters the washing water tank 23, and the washing water in the washing water tank 23 is introduced into the water storage tank 1 through the washing water pump 22 to realize the recycling of the washing water. Finally, the purified phosphogypsum is obtained by the filter press 25.

[0040] In the description of this specification, the descriptions with reference to the terms "a set of embodiments", "a specific embodiment", "a specific example", "some embodiments", "examples", "specific examples", etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0041] The scope of protection of the present invention is not limited to the above-described embodiments. Obviously, those skilled in the art may make various modifications and variations to the present invention without departing from the scope and spirit of the present invention. If such modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations.

Claims

1. A semi-hydrated phosphogypsum purification system, characterized in that: It includes a reactor, a flotation device, a gravity separation device, a high-frequency screen and a filter press module, wherein the reactor is provided with a semi-hydrated phosphogypsum inlet and a water inlet, the reactor is connected to N flotation devices connected in series, the Nth flotation device is connected to M gravity separation devices connected in series, the M gravity separation devices are all connected to the high-frequency screen, and the high-frequency screen is connected to the filter press module; N is an integer ≥2, and M is an integer ≥2.

2. The hemihydrate phosphogypsum purification system according to claim 1, characterized in that: The reactor is connected to the upper inlet of the first flotation device, the lower outlet of the previous flotation device is connected to the upper inlet of the next flotation device, and the material is passed between the two flotation columns connected in series by the potential difference; the lower outlet of the Nth flotation device is connected to the upper inlet of the first gravity separation device; The lower outlet of the previous gravity sorting device is connected to the upper inlet of the next gravity sorting device, and the upper outlets of the M gravity sorting devices are all connected to the high-frequency screen inlet.

3. The hemihydrate phosphogypsum purification system according to claim 1 or 2, characterized in that: The upper outlets of N flotation devices are all connected to the slurry tank, the lower outlet of the Mth gravity separation device is connected to the slurry tank, and the upper outlet of the high-frequency screen is connected to the slurry tank.

4. The hemihydrate phosphogypsum purification system according to claim 1 or 2, characterized in that: The flotation device is a flotation column.

5. The hemihydrate phosphogypsum purification system according to claim 1 or 2, characterized in that: The gravity separation device is a cyclone.

6. The hemihydrate phosphogypsum purification system according to claim 1 or 2, characterized in that: The reactor is connected to the first flotation device through an emulsification pump and a feed pump.

7. The hemihydrate phosphogypsum purification system according to claim 1 or 2, characterized in that: The Nth flotation device is connected to the first gravity separation device through a feed pump.

8. The hemihydrate phosphogypsum purification system according to claim 1 or 2, characterized in that: The lower outlet of the previous gravity separation device is connected to the feeding trough, and then connected to the upper inlet of the next gravity separation device through the feeding pump.

9. The hemihydrate phosphogypsum purification system according to claim 1 or 2, characterized in that: The filter press module includes a filter press, a raw water tank connected to the filter press inlet, a compressed air storage tank, a pressing water tank, and a washing water tank and a filtrate tank connected to the filter press outlet.

10. The hemihydrate phosphogypsum purification system according to claim 9, characterized in that: The lower outlet of the high-frequency screen is connected to the inlet of the filter press through the fine material tank.

11. The hemihydrate phosphogypsum purification system according to claim 10, characterized in that: The concentrate tank is connected to the filter press inlet through the concentrate pump, the raw water tank for washing water is connected to the filter press inlet through the washing water pump, and the squeeze water tank is connected to the filter press inlet through the squeeze water pump.

12. The hemihydrate phosphogypsum purification system according to claim 9, characterized in that: It also includes a water storage tank, which is connected to the water inlet of the reactor, and the washing water tank is connected to the water storage tank.

13. The hemihydrate phosphogypsum purification system according to claim 12, characterized in that: The water storage tank is connected to the water inlet of the reactor through a water supply pump, and the washing water tank is connected to the water storage tank through a washing water pump.

14. The hemihydrate phosphogypsum purification system according to claim 1 or 2, characterized in that: The N is 2, 3, 4, 5, 6, 7, 8, 9 or 10; the M is 2, 3, 4, 5, 6, 7, 8, 9 or 10.

15. A semi-aqueous wet-process phosphoric acid production system, characterized in that: It comprises the hemihydrate phosphogypsum purification system according to any one of claims 1 to 14 and a hemihydrate wet-process phosphoric acid production module, wherein the hemihydrate phosphogypsum discharge port of the hemihydrate wet-process phosphoric acid production module is connected to the hemihydrate phosphogypsum inlet of the reactor.

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