Phosphogypsum recycling system

Abstract

Provided in the present invention is a phosphogypsum recycling system, comprising an acid washing tank, a clarification tower and a reaction furnace, wherein the acid washing tank is provided with a raw material feeding port and a washing liquid discharging port; the clarification tower is provided with a washing liquid feeding port, an acid washing slurry discharging port and an acid washing clarified liquid discharging port; the reaction furnace is provided with a crude product feeding port, a fuel feeding port, an acid gas discharging port and a product discharging port; and the washing liquid discharging port is connected to the washing liquid feeding port via a washing liquid pipeline, and the acid washing slurry discharging port is connected to the crude product feeding port. In the present invention, a large amount of calcium oxide having a wide application range is generated while waste residues are cleaned and treated. Moreover, it is ensured that tail gas meets the environmental protection standard and reaches the discharge standard, and by-products of sulfuric acid and steam are produced. This not only treats the waste residues of phosphogypsum, but also generates a certain economic value.

Description

A phosphogypsum recycling system

[0001] This application claims priority to Chinese patent application 2024226753707, filed on November 4, 2024. The entire contents of the aforementioned Chinese patent application are incorporated herein by reference. Technical Field

[0002] This invention relates to a phosphogypsum recycling system. Background Technology

[0003] Phosphogypsum is an industrial waste produced during the production of phosphate fertilizers. Its main component is calcium sulfate dihydrate (CaSO4·2H2O). The wet process production of 1 ton of phosphoric acid (calculated as P2O5) generates approximately 5 tons of phosphogypsum. Currently, the world's annual phosphogypsum emissions are approximately 200 million tons, while my country's annual emissions exceed 20 million tons, with stockpiles exceeding 300 million tons. The utilization rate is only 30%. Besides occupying a large amount of land, phosphogypsum stockpiles also cause environmental problems such as dust, groundwater, and soil pollution.

[0004] With the continuous expansion of the wet-process phosphoric acid processing industry both domestically and internationally, the comprehensive utilization of phosphogypsum has become a common issue for the sustainable development of the industry. The main ways to comprehensively utilize phosphogypsum in my country are to replace natural gypsum in the production of cement retarders, the preparation of building materials, the production of soil conditioners, and the co-production of acid and cement.

[0005] While these methods are currently used industrially, they are insufficient to solve the comprehensive utilization of phosphogypsum. For example, although effective in producing cement retarders, their application is limited by the scale of cement production and the number of manufacturers using phosphogypsum to replace natural gypsum. The use of phosphogypsum in building materials is also limited due to the high impurity content affecting material performance. Phosphogypsum can be used to produce soil conditioners for saline-alkali land and soil structure improvement, but its widespread adoption still has a long way to go. The co-production of acid and cement from phosphogypsum is still in its early stages, requiring highly precise instruments and equipment for raw material preparation. The operation and control of rotary kilns are challenging due to the narrow decomposition range of gypsum and numerous side reactions. Therefore, the process of co-producing acid and cement from phosphogypsum still requires innovation and improvement in both technology and operation. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a phosphogypsum recycling system.

[0007] The present invention solves the above-mentioned technical problems through the following technical solution:

[0008] This invention provides a phosphogypsum recycling system, which includes an acid washing tank, a clarification tower and a reaction furnace;

[0009] The pickling tank is provided with a raw material inlet and a washing liquid outlet; the clarification tower is provided with a washing liquid inlet, a pickling slurry outlet and a pickling clear liquid outlet; the reactor is provided with a crude product inlet, a fuel inlet, an acid gas outlet and a product outlet.

[0010] The washing liquid outlet and the washing liquid inlet are connected through a washing liquid pipeline, and the pickling slurry outlet is connected to the crude product inlet.

[0011] The pickling solution outlet is also connected to the pickling solution treatment unit, which includes a pickling solution collection tank. The pickling solution collection tank is provided with a solution inlet, a treatment agent inlet, and a treatment slurry outlet. The solution outlet is connected to the solution inlet.

[0012] The pickling solution treatment unit further includes a slurry filter, which includes a slurry inlet, a reflux filtrate outlet, and a filter cake outlet; the slurry inlet and the slurry outlet are connected by a slurry pipeline.

[0013] In this invention, the main component of phosphogypsum is dihydrate gypsum (CaSO4·2H2O). Besides the main component calcium sulfate, it also contains small amounts of phosphoric acid, silicon, fluorine, magnesium, iron, aluminum, and organic impurities. The presence of these impurities significantly hinders the reuse of phosphogypsum. These impurities must be removed before the calcination stage (dissolved in dilute acid) to reduce their impact on subsequent products such as CaO and acid gas. F - Since it cannot be discharged in the solution, CaO is added to the liquid to reduce the concentration of F in the solution. - It exists in the form of CaF2 for collection and storage.

[0014] In this invention, the pickling tank may be equipped with a stirring device.

[0015] In this invention, a washing liquid pump may be installed on the washing liquid pipeline.

[0016] In this invention, the raw material inlet may include a phosphogypsum inlet and a dilute acid inlet.

[0017] In this invention, a slurry pump may be installed on the slurry processing pipeline. The pickling tank may also have a filtrate return port, and the filtrate return outlet is connected to the filtrate return port via a filtrate return pipeline. A filtrate return pump may be installed on the filtrate return pipeline. The slurry processing filter may be a plate and frame filter.

[0018] In this invention, conventionally, the height of the pickling slurry outlet is lower than the height of the pickling clear liquid outlet.

[0019] In this invention, an acid pickling slurry treatment unit may be provided between the pickling slurry outlet and the coarse product inlet. The acid pickling slurry treatment unit includes an acid pickling slurry filter and a dryer. The acid pickling slurry filter is provided with an acid pickling slurry inlet, an acid pickling filtrate outlet, and an acid pickling filter cake outlet. The dryer is provided with an acid pickling filter cake inlet, a coarse product outlet, and a tail gas outlet. The acid pickling slurry inlet is connected to the acid pickling slurry outlet, the acid pickling filter cake outlet is connected to the acid pickling filter cake inlet, and the coarse product outlet is connected to the coarse product inlet.

[0020] The pickling slurry treatment unit may further include a dryer dust collector, which has an exhaust gas inlet, a second exhaust gas outlet, and a second coarse product outlet. The exhaust gas inlet is connected to the exhaust gas outlet, and the second coarse product outlet is connected to the coarse product inlet. The second exhaust gas outlet may be connected to the inlet of the drying fan. The pickling slurry treatment unit may also include a conveyor, with the coarse product outlet connected to the inlet of the conveyor and the outlet of the conveyor connected to the coarse product inlet. The dryer may be a drum dryer. The drum of the drum dryer may be slightly inclined and capable of rotation. The drum of the drum dryer may be equipped with forward-moving lifting plates. The conveyor may include a belt conveyor and a bucket elevator connected in sequence. A crusher may also be provided between the outlet of the conveyor and the coarse product inlet. The crusher may be a vibrating crusher. The pickling slurry filter may be a plate and frame filter.

[0021] In a specific embodiment of the present invention, an acid pickling slurry treatment unit may be provided between the acid pickling slurry outlet and the crude product inlet. The acid pickling slurry treatment unit includes an acid pickling slurry filter, a dryer, a dryer dust collector, a belt conveyor, a bucket elevator, and a crusher.

[0022] The pickling slurry filter is provided with a pickling slurry inlet, a pickling filtrate outlet, and a pickling filter cake outlet; the dryer is provided with a pickling filter cake inlet, a coarse product outlet, and a tail gas outlet; the dryer dust collector is provided with a tail gas inlet, a second tail gas outlet, and a second coarse product outlet.

[0023] The pickling slurry inlet is connected to the pickling slurry outlet. The pickling filtrate outlet is connected to the clear liquid inlet via a clear liquid pipe, and a clear liquid pump is installed on the clear liquid pipe. The pickling filter cake outlet is connected to the pickling filter cake inlet. The coarse product outlet and the second coarse product outlet are connected to the inlet end of the belt conveyor. The outlet end of the belt conveyor is connected to the inlet end of the bucket elevator. The outlet end of the bucket elevator is connected to the inlet end of the crusher. The outlet end of the crusher is connected to the coarse product inlet. The exhaust gas inlet is connected to the exhaust gas outlet. The second exhaust gas outlet is connected to the inlet of the drying induced draft fan.

[0024] In this invention, the acid gas outlet and the product outlet can also be connected to a product processing unit. The product processing unit includes an acid gas dust collector and a silo. The acid gas dust collector has an acid gas inlet, a second acid gas outlet, and a second product outlet. The acid gas inlet is connected to the acid gas outlet, and the second product outlet and the product outlet are connected to the inlet of the silo. The outlet of the silo can also be connected to the inlet of a product crusher.

[0025] In this invention, the reactor can be a cruciform reactor. There can be two fuel inlets, located on opposite sides of the reactor. The acid gas outlet can be located at the top of the reactor. The product outlet can be located at the bottom of the reactor.

[0026] In this invention, the furnace lining of the reactor can be made of refractory bricks.

[0027] The positive and progressive effects of this invention are as follows:

[0028] (1) In this invention, phosphogypsum is comprehensively utilized, the process is simpler and more operable, and it can be promoted in the industrial field. It can not only fully recover and utilize resources such as sulfur and calcium in phosphogypsum, but also ensure that the entire process is free from wastewater, waste residue and air pollution. It solves the problems of phosphogypsum storage, land occupation and pollution, and alleviates the problem of sulfur resource shortage in my country. It turns waste into treasure and realizes the sustainable development of resources.

[0029] (2) In this invention, the operation is simple, the energy consumption is low, the processing cost is low, and the environmental benefits are obvious. While cleaning and treating the waste residue, no other harmful substances are generated. The products calcium oxide and sulfuric acid containing SO2 gas have good economic benefits. In the end, the purpose of safe incineration of industrial waste residue, environmental protection compliance, energy conservation and emission reduction is achieved. At the same time, the exhaust gas meets the environmental protection standards and is discharged in compliance with the standards. Sulfuric acid and steam are produced as by-products. It not only properly treats the waste residue phosphogypsum, but also generates certain economic value. Attached Figure Description

[0030] Figure 1 is a schematic diagram of the phosphogypsum recycling system of Example 1;

[0031] Figure 2 is a schematic diagram of the phosphogypsum recycling system in Example 2;

[0032] The following are labeled in the diagram: Pickling tank V-101, Pickling liquid collection tank V-102, Silo V-103, Clarifying tower T-101, Reactor R-101, Washing liquid pump P-101, Clear liquid pump P-102, Processing slurry pump P-103, Reflux filtrate pump P-104, Pickling slurry filter F-101, Processing slurry filter F-102, Dryer D-101, Dryer dust collector X-101, Crusher X-102, Acid gas dust collector X-103, Product crusher X-104, Drying induced draft fan C-101, Belt conveyor L-101, Bucket elevator L-102. Detailed Implementation

[0033] The present invention will be described more clearly and completely below with reference to a preferred embodiment and the accompanying drawings.

[0034] Example 1

[0035] A phosphogypsum recycling system, as shown in Figure 1, includes an acid washing tank V-101, a clarification tower T-101, and a reactor R-101. The acid washing tank V-101 is provided with a raw material inlet, a washing liquid outlet, and a filtrate return outlet. The clarification tower T-101 is provided with a washing liquid inlet, an acid washing slurry outlet, and an acid washing clear liquid outlet. The reactor R-101 is provided with a crude product inlet, a fuel inlet, an acid gas outlet, and a product outlet. The washing liquid outlet is connected to the washing liquid inlet via a washing liquid pipeline.

[0036] In this embodiment, the raw material inlets include a phosphogypsum inlet and a dilute acid inlet. In this embodiment, the pickling tank V-101 is equipped with a stirring device. In this embodiment, the height of the pickling slurry outlet is lower than the height of the pickling clear liquid outlet. In this invention, the reactor R-101 is a cross-shaped reactor with two fuel inlets located on either side of the reactor R-101. The acid gas outlet can be located at the top of the reactor R-101, and the product outlet can be located at the bottom of the reactor R-101. In this invention, the furnace chamber of the reactor R-101 is lined with refractory bricks.

[0037] In this embodiment, the pickling solution outlet is also connected to the pickling solution treatment unit, which includes a pickling solution collection tank V-102 and a slurry filter F-102. The pickling solution collection tank V-102 is provided with a clear solution inlet, a treatment agent inlet, and a slurry outlet. The slurry filter F-102 includes a slurry inlet, a reflux filtrate outlet, and a filter cake outlet. The clear solution outlet is connected to the clear solution inlet, the slurry inlet and the slurry outlet are connected via a slurry pipeline, and the reflux filtrate outlet and the filtrate reflux outlet are connected via a reflux filtrate pipeline. In this embodiment, the slurry filter F-102 is a plate and frame filter.

[0038] In this embodiment, an acid pickling slurry treatment unit may be provided between the pickling slurry outlet and the coarse product inlet. The acid pickling slurry treatment unit includes an acid pickling slurry filter F-101 and a dryer D-101. The acid pickling slurry filter F-101 has an acid pickling slurry inlet, an acid pickling filtrate outlet, and an acid pickling filter cake outlet. The dryer D-101 has an acid pickling filter cake inlet, a coarse product outlet, and a tail gas outlet. The acid pickling slurry inlet is connected to the acid pickling slurry outlet, the acid pickling filter cake outlet is connected to the acid pickling filter cake inlet, the coarse product outlet is connected to the coarse product inlet, and the acid pickling filtrate outlet is connected to the clear liquid inlet. In this embodiment, the dryer D-101 is a drum dryer.

[0039] In this embodiment, the waste phosphogypsum generated during the phosphate fertilizer production process is recycled and reused to generate products such as calcium oxide and acidic gas containing SO2. This involves the following four processing steps:

[0040] 1. Acid hydrolysis of phosphogypsum with dilute sulfuric acid: The phosphogypsum entering through the feed inlet is mainly composed of dihydrate gypsum (CaSO4·2H2O), and also contains small amounts of phosphoric acid, silicon, fluorine, magnesium, iron, aluminum, and organic impurities. The Fe in the phosphogypsum... 3+ Al 3+ F - Na + K +Metal ions are stirred in pickling tank V-101 to achieve more complete dissolution and more effective removal of impurities, resulting in higher purity calcium oxide. Most of these impurity ions dissolve in dilute sulfuric acid (25wt%-30wt%) introduced from the dilute acid inlet. The mass ratio of phosphogypsum to dilute sulfuric acid is 1:(1.5-3). After pickling, the pH of the phosphogypsum is controlled between 5 and 6. The dilute acid removes approximately 95%-98% of the phosphorus, 50%-60% of silicon, 50%-60% of iron, 70%-80% of fluorine, and 65%-75% of potassium. Small amounts of silicon, fluorine, aluminum, and iron remain after pickling. The washing liquid from the phosphogypsum pickling is fed into clarifier T-101. This liquid, a liquid-solid mixture, settles in clarifier T-101, separating into two layers: a lower slurry layer and an upper clear liquid layer. The clarifier T-101 operates at room temperature and a pressure of approximately 0.3 MPaG.

[0041] 2. Solid filtration, drying and pulverization: The pickling slurry in the lower layer of the clarifier T-101 enters the pickling slurry filter F-101 for filtration. The filtered pickling liquid is then passed into the pickling liquid collection tank V-102. The filtered pickling filter cake enters the dryer D-101 for drying at a temperature of 150-160℃ to obtain a crude product. The generated tail gas is sent to the acid tail washing tower.

[0042] 3. Calcination: The crude product enters reactor R-101 and reacts with the coal gas introduced through the fuel inlet. This reaction requires high temperature to ensure complete reaction and reduce the occurrence of side reactions. Reactor R-101 operates at atmospheric pressure, and the reaction temperature is 1350-1450℃. The main reactions occurring here are:

[0043] CaSO4 + CO = SO2 + CaO + CO2

[0044] CaSO4 + H2 = SO2 + CaO + H2O

[0045] After a series of processing steps, the main component of phosphogypsum, CaSO4, reacts with coal gas to produce solid CaO, which flows to the product outlet. Because the reaction occurs in excess coal gas, the subsequent calcination yields not only CaO and SO2, but also CO2 and CO as byproducts. This gas can be used as syngas in the wet sulfuric acid production unit.

[0046] 4. Deep Treatment of Waste Liquid: The pickling liquid from the upper layer of clarifier T-101 and the pickling slurry obtained from filter F-101 enter the pickling liquid collection tank V-102. CaO is added through the feed inlet of the treatment agent, and a reaction occurs to form CaF2 precipitate. The main reactions occurring here are:

[0047] 2F -+CaO(s)+H2O→CaF2(s)+2OH -

[0048] The obtained slurry is filtered by the slurry filter F-102, and the resulting reflux filtrate is fed into the pickling tank V-101 for washing and recycling. The resulting CaF2 solid is collected and stored.

[0049] Example 2

[0050] A phosphogypsum recycling system, as shown in Figure 2, includes an acid washing tank V-101, a clarification tower T-101, and a reactor R-101. The acid washing tank V-101 is provided with a raw material inlet, a washing liquid outlet, and a filtrate return outlet. The clarification tower T-101 is provided with a washing liquid inlet, an acid washing slurry outlet, and an acid washing clear liquid outlet. The reactor R-101 is provided with a crude product inlet, a fuel inlet, an acid gas outlet, and a product outlet. The washing liquid outlet is connected to the washing liquid inlet via a washing liquid pipeline.

[0051] In this embodiment, the pickling tank V-101 is equipped with a stirring device. In this embodiment, a washing liquid pump P-101 is installed on the washing liquid pipeline. In this embodiment, the raw material inlets include a phosphogypsum inlet and a dilute acid inlet. In this embodiment, the height of the pickling slurry outlet is lower than the height of the pickling clear liquid outlet. In this embodiment, the reactor R-101 is a cross-shaped reactor with two fuel inlets located on either side of the reactor R-101. The acid gas outlet can be located at the top of the reactor R-101, and the product outlet can be located at the bottom of the reactor R-101.

[0052] In this embodiment, the pickling solution outlet is also connected to the pickling solution treatment unit, which includes a pickling solution collection tank V-102 and a slurry filter F-102. The pickling solution collection tank V-102 is provided with a clear solution inlet, a treatment agent inlet, and a slurry outlet. The slurry filter F-102 includes a slurry inlet, a reflux filtrate outlet, and a filter cake outlet. The clear solution outlet is connected to the clear solution inlet, and the slurry inlet and outlet are connected through a slurry pipeline. A slurry pump P-103 is provided on the slurry pipeline. The reflux filtrate outlet and the filtrate reflux outlet are connected through a reflux filtrate pipeline. A reflux filtrate pump P-104 is provided on the reflux filtrate pipeline.

[0053] In this embodiment, an acid pickling slurry treatment unit is also provided between the pickling slurry outlet and the coarse product inlet. The acid pickling slurry treatment unit includes an acid pickling slurry filter F-101, a dryer D-101, a dryer dust collector X-101, a belt conveyor L-101, a bucket elevator L-102, and a crusher X-102. The acid pickling slurry filter F-101 is provided with an acid pickling slurry inlet, an acid pickling filtrate outlet, and an acid pickling filter cake outlet. The dryer D-101 is provided with an acid pickling filter cake inlet, a coarse product outlet, and a tail gas outlet. The dryer dust collector X-101 is provided with a tail gas inlet, a second tail gas outlet, and a second coarse product outlet. The acid pickling slurry inlet and... The pickling slurry outlet is connected to the pickling filtrate outlet, which is connected to the clear liquid inlet via a clear liquid pipeline. A clear liquid pump P-102 is installed on the clear liquid pipeline. The pickling filter cake outlet is connected to the pickling filter cake inlet. The coarse product outlet and the second coarse product outlet are connected to the inlet end of the belt conveyor L-101. The outlet end of the belt conveyor L-101 is connected to the inlet end of the bucket elevator L-102. The outlet end of the bucket elevator L-102 is connected to the inlet end of the crusher X-102. The outlet end of the crusher X-102 is connected to the coarse product inlet. The exhaust gas inlet is connected to the exhaust gas outlet, and the second exhaust gas outlet is connected to the inlet of the drying induced draft fan C-101. In this embodiment, the pickling slurry filter F-101 is a plate and frame filter. In this embodiment, the crusher X-102 is a vibrating crusher.

[0054] In this embodiment, the dryer D-101 is a drum dryer. The drum of the drum dryer is slightly tilted and can rotate. The height of the pickling filter cake inlet is higher than the height of the crude product outlet. The drum of the drum dryer is equipped with forward lifting plates, which continuously lift and sprinkle the material during the rotation of the drum, so that it can fully contact the hot airflow, thereby improving the drying efficiency and moving the material forward.

[0055] In this embodiment, the acid gas outlet and the product outlet are also connected to the product processing unit. The product processing unit includes an acid gas dust collector X-103 and a silo V-103. The acid gas dust collector X-103 is provided with an acid gas inlet, a second acid gas outlet, and a second product outlet. The acid gas inlet is connected to the acid gas outlet. The second product outlet and the product outlet are connected to the inlet of the silo V-103. The outlet of the silo V-103 is also connected to the inlet of the product crusher X-104.

[0056] In this embodiment, the main components of phosphogypsum are: approximately 86.7 wt% CaSO4·2H2O, approximately 8.8 wt% SiO2, approximately 2.4 wt% Ca3P2O8, and trace amounts of MgO, CaF2, and Fe2(SO4)3. The total phosphogypsum volume is 2026 kg / h, and the treatment process is as follows:

[0057] The phosphogypsum entering from the raw material feed inlet and the 30 wt% dilute sulfuric acid entering from the dilute acid feed inlet are dissolved with stirring in the pickling tank V-101 at a mass ratio of 1:2, generating a variety of sulfate solutions and a precipitate mixture. The obtained solid-liquid mixture is pumped into the clarification tower T-101 by the washing liquid pump P-101 and settles in the clarification tower T-101 into two layers, namely the lower slurry layer and the upper clear liquid layer. The operating temperature of the clarification tower T-101 is normal temperature, and the operating pressure is 0.3 MPaG.

[0058] The pickling slurry in the lower layer of the clarification tower T-101 enters the pickling slurry filter F-101 for filtration. The filtered pickling clear liquid is pumped into the pickling clear liquid collection tank V-102 by the clear liquid pump P-102. CaO is added from the treatment agent feed inlet, and a reaction occurs to form CaF2 precipitate, resulting in the formation of treatment slurry in the pickling clear liquid collection tank V-102, which is a solid-liquid mixed slurry. The treatment slurry is pumped into the treatment slurry filter F-102 by the treatment slurry pump P-103. The reflux filtrate obtained after filtration is pumped into the pickling tank V-101 by the reflux filtrate pump P-104 for washing and recycling, and the obtained CaF2 solid is collected and stored.

[0059] The pickling filter cake filtered by the pickling slurry filter F-101, which is CaSO4 solid containing a certain amount of moisture, first enters the dryer D-101 for drying at a drying temperature of 160°C, and then passes through the dryer dust collector X-101 for dust removal. The small-volume solids deposited and the solids dried by the dryer D-101 are transported together by the belt conveyor L-101 and the bucket elevator L-102 to the crusher X-102 for crushing, and the particle size of the crushed crude product is 10 μm < D90 < 90 μm. The tail gas generated by the dryer dust collector X-101 is sent to the acid tail washing tower for acid making.

[0060] The crude product enters the reaction furnace R-101, and excessive gas is introduced from the fuel feed inlet. At 1350°C, the CaSO4 solid reacts with CO and H2 in the gas to generate CaO solid and SO2 and CO2 gases. The SO2 and CO2 gases and the excessive gas are sent to the acid gas dust collector X-103 for dust removal after further cooling, and then can enter the subsequent acid making unit. The CaO solid generated by the reaction furnace R-101 is discharged from the product discharge port into the silo V-103, and together with the small-particle CaO solid falling after dust removal by the acid gas dust collector X-103, it is crushed to the required size by the product crusher X-104 and then packaged and transported out.

[0061] Although the specific embodiments of the present invention are described above, those skilled in the art should understand that these are only examples. Without departing from the principles and essence of the present invention, various changes or modifications can be made to these embodiments. Therefore, the protection scope of the present invention is defined by the appended claims.

Claims

1. A phosphogypsum recycling system, characterized in that, It includes a pickling tank (V-101), a clarification tower (T-101), and a reactor (R-101); The pickling tank (V-101) is equipped with a raw material inlet and a washing liquid outlet; the clarification tower (T-101) is equipped with a washing liquid inlet, a pickling slurry outlet and a pickling clear liquid outlet; the reactor (R-101) is equipped with a crude product inlet, a fuel inlet, an acid gas outlet and a product outlet. The washing liquid outlet and the washing liquid inlet are connected through a washing liquid pipeline, and the pickling slurry outlet is connected to the crude product inlet. The pickling solution outlet is also connected to the pickling solution treatment unit, which includes a pickling solution collection tank (V-102). The pickling solution collection tank (V-102) is provided with a solution inlet, a treatment agent inlet, and a treatment slurry outlet; the solution outlet is connected to the solution inlet. The pickling solution treatment unit further includes a slurry filter (F-102), which includes a slurry inlet, a reflux filtrate outlet, and a filter cake outlet. The slurry inlet and the slurry outlet are connected via a slurry pipeline. A slurry pump (P-103) is installed on the slurry pipeline. The pickling tank (V-101) is also provided with a filtrate return port, and the filtrate return outlet is connected to the filtrate return port through a filtrate return pipeline.

2. The phosphogypsum recycling system as described in claim 1, characterized in that, The pickling tank (V-101) is equipped with a stirring device; the washing liquid pipeline is equipped with a washing liquid pump (P-101); the raw material inlet includes a phosphogypsum inlet and a dilute acid inlet; the height of the pickling slurry outlet is lower than the height of the pickling clear liquid outlet.

3. The phosphogypsum recycling system according to at least one of claims 1 and 2, characterized in that, The reflux filtrate pipeline is equipped with a reflux filtrate pump (P-104); the slurry treatment filter (F-102) is a plate and frame filter.

4. The phosphogypsum recycling system according to at least one of claims 2 and 3, characterized in that, A pickling slurry treatment unit is also provided between the pickling slurry outlet and the coarse product inlet. The pickling slurry treatment unit includes a pickling slurry filter (F-101) and a dryer (D-101). The pickling slurry filter (F-101) is provided with a pickling slurry inlet, a pickling filtrate outlet, and a pickling filter cake outlet. The dryer (D-101) is provided with a pickling filter cake inlet, a coarse product outlet, and a tail gas outlet. The pickling slurry inlet is connected to the pickling slurry outlet, the pickling filter cake outlet is connected to the pickling filter cake inlet, and the coarse product outlet is connected to the coarse product inlet.

5. The phosphogypsum recycling system as described in claim 4, characterized in that, The pickling slurry treatment unit also includes a dryer dust collector (X-101), which is provided with an exhaust gas inlet, a second exhaust gas outlet, and a second coarse product outlet. The exhaust gas inlet is connected to the exhaust gas outlet, and the second coarse product outlet is connected to the coarse product inlet. The second exhaust outlet can be connected to the air inlet of the drying blower (C-101); the pickling slurry treatment unit also includes a conveyor, the crude product outlet is connected to the feed end of the conveyor, and the discharge end of the conveyor is connected to the crude product inlet.

6. The phosphogypsum recycling system as described in claim 5, characterized in that, The dryer (D-101) is a drum dryer; the drum of the drum dryer is an inclined and rotatable drum; the drum of the drum dryer is equipped with forward lifting plates; the conveyor includes a belt conveyor (L-101) and a bucket elevator (L-102) connected in sequence; a crusher (X-102) is also provided between the discharge end of the conveyor and the feed inlet of the coarse product; the crusher (X-102) is a vibrating crusher; the pickling slurry filter (F-101) is a plate and frame filter.

7. The phosphogypsum recycling system according to at least one of claims 5 and 6, characterized in that, A pickling slurry treatment unit may also be provided between the pickling slurry outlet and the crude product inlet. The pickling slurry treatment unit includes a pickling slurry filter (F-101), a dryer (D-101), a dryer dust collector (X-101), a belt conveyor (L-101), a bucket elevator (L-102), and a crusher (X-102). The pickling slurry filter (F-101) is equipped with a pickling slurry inlet, a pickling filtrate outlet, and a pickling filter cake outlet; the dryer (D-101) is equipped with a pickling filter cake inlet, a coarse product outlet, and a tail gas outlet; the dryer dust collector (X-101) is equipped with a tail gas inlet, a second tail gas outlet, and a second coarse product outlet. The pickling slurry inlet is connected to the pickling slurry outlet. The pickling filtrate outlet is connected to the clear liquid inlet via a clear liquid pipe. A clear liquid pump (P-102) is installed on the clear liquid pipe. The pickling filter cake outlet is connected to the pickling filter cake inlet. The coarse product outlet and the second coarse product outlet are connected to the inlet end of the belt conveyor (L-101). The outlet end of the belt conveyor (L-101) is connected to the inlet end of the bucket elevator (L-102). The outlet end of the bucket elevator (L-102) is connected to the inlet end of the crusher (X-102). The outlet end of the crusher (X-102) is connected to the coarse product inlet. The exhaust gas inlet is connected to the exhaust gas outlet. The second exhaust gas outlet is connected to the inlet of the drying induced draft fan (D-101).

8. The phosphogypsum recycling system according to at least one of claims 1-7, characterized in that, The acid gas outlet and the product outlet can also be connected to a product processing unit. The product processing unit includes an acid gas dust collector (X-103) and a silo (V-103). The acid gas dust collector (X-103) is provided with an acid gas inlet, a second acid gas outlet, and a second product outlet. The acid gas inlet is connected to the acid gas outlet, and the second product outlet and the product outlet are connected to the inlet of the silo (V-103). The outlet of the silo (V-103) is also connected to the inlet of the product crusher (X-104).

9. The phosphogypsum recycling system according to at least one of claims 1-8, characterized in that, The reactor (R-101) is a cross-shaped reactor; there are two fuel inlets, located on both sides of the reactor (R-101); the acid gas outlet is located at the top of the reactor (R-101); and the product outlet is located at the bottom of the reactor (R-101).

10. The phosphogypsum recycling system according to at least one of claims 1-9, characterized in that, The furnace lining of the reactor (R-101) is made of refractory bricks.

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