Deep countercurrent purification system for phosphogypsum

Abstract

The utility model relates to the technical field of ardealite processing equipment, in particular to a deep countercurrent purification system for ardealite, which comprises a first repulping tank, the bottom output end of the first repulping tank is connected to a hydrocyclone through a first delivery pump, the bottom of the hydrocyclone is provided with a discharge port, the discharge port is connected to a second repulping tank through a pipeline, and the second repulping tank is provided with a second delivery pump. And one side of the bottom of the second re-pulping tank is connected to a slurry distribution box through a second conveying pump, and a dehydration area, a first washing area and a second washing area are sequentially arranged in the slurry distribution box from left to right. According to the deep countercurrent purification system for ardealite, efficient and environment-friendly purification treatment of ardealite is realized through unique process design and equipment combination. The system is based on physical water washing and is combined with a countercurrent washing technology, so that the impurity removal efficiency is remarkably improved, the problem of sewage generated in the traditional water washing process is effectively solved, and the risk of secondary pollution is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of phosphogypsum processing equipment, in particular to a phosphogypsum deep countercurrent purification system. Background Art

[0002] Phosphogypsum is a by-product of the wet phosphoric acid production process. Since it contains impurities such as water-soluble P2O5, water-soluble F and some organic matter, the utilization of phosphogypsum has become an industry problem. In order to expand the downstream application of phosphogypsum, it is necessary to purify the phosphogypsum.

[0003] At present, the chemical, physical and thermal treatment methods commonly used for phosphogypsum can achieve a certain degree of purification of phosphogypsum. The chemical method can remove most phosphate, fluoride and organic impurities, and has a high impurity removal rate. However, except for the lime neutralization method, which has the advantages of simple process, low cost and strong applicability, most of the other chemical treatment methods are high in cost and low in applicability of treatment agents. They are only in the laboratory research stage and are difficult to promote and apply on a large scale. The thermal treatment method mainly uses fast burning technology to remove most of the insoluble impurities in phosphogypsum. Although it has less pollution to the environment, it is a high-energy consumption process with a small processing scale, and it is difficult to achieve large-scale purification of phosphogypsum.

[0004] Physical method is the most commonly used method for phosphogypsum purification in the phosphorus chemical industry. Physical flotation has a considerable effect on impurity removal, but it also has great limitations. The efficiency of impurity removal mainly depends on the size of gypsum crystal particles. Water washing purification is the most effective way to remove impurities in physical purification, but the wastewater generated by water washing is prone to secondary pollution. The treatment of wash water is the key to water washing purification. Utility Model Content

[0005] The purpose of the utility model is to provide a deep countercurrent purification system for phosphogypsum to solve the problem that the physical method proposed in the above background technology is currently the commonly used purification method for phosphogypsum in the phosphorus chemical industry. The physical flotation removal effect is quite impressive, but it also has great limitations. The efficiency of impurity removal mainly depends on the size of the gypsum crystal particles. Water washing purification is the most effective way to remove impurities in the physical purification method, but the sewage generated by the water washing treatment is prone to secondary pollution. The treatment of wash water is the key issue of water washing purification.

[0006] To achieve the above-mentioned purpose, the utility model provides a deep countercurrent purification system for phosphogypsum, including a first re-slurry tank, the bottom output end of the first re-slurry tank is connected to a hydrocyclone through a first delivery pump, a discharge port is provided at the bottom of the hydrocyclone, the discharge port is connected to a second re-slurry tank through a pipeline, one side of the bottom of the second re-slurry tank is connected to a slurry distribution box through a second delivery pump, and the interior of the slurry distribution box is provided with a dehydration zone, a first washing zone and a second washing zone in sequence from left to right.

[0007] Preferably, the hydrocyclone is provided with an overflow port at the top and a discharge port at the bottom.

[0008] Preferably, a vacuum filter press chamber is provided inside the dehydration zone, and a countercurrent washing chamber is provided inside the first washing zone and the second washing zone.

[0009] Preferably, a heat exchanger is provided outside the secondary washing zone, the input end of the heat exchanger is connected to the vacuum pump through a pipeline, the output end of the heat exchanger is connected to the secondary washing zone through a pipeline, and the input end of the vacuum pump is connected to process water through a pipeline.

[0010] Preferably, the bottom of the secondary washing zone is connected to the top of the primary washing zone through a pipeline.

[0011] Preferably, the bottom of the first washing zone is connected to the first reslurry tank through a pipeline.

[0012] Preferably, the bottom of the dehydration zone is connected to an external production system via a pipeline.

[0013] Preferably, the top of the dehydration zone is connected to the output end of the second delivery pump through a pipeline.

[0014] Compared with the prior art, the utility model has the following beneficial effects:

[0015] In this phosphogypsum deep countercurrent purification system, the unique process design and equipment combination realize the efficient and environmentally friendly purification of phosphogypsum. Based on physical water washing and combined with countercurrent washing technology, the system not only significantly improves the removal efficiency of impurities, but also effectively solves the sewage problem generated in the traditional water washing process and reduces the risk of secondary pollution. Specifically, the system enables phosphogypsum to fully contact with water during the purification process through the reasonable layout of multiple re-slurry tanks and slurry distribution boxes, thereby more thoroughly removing impurities therein. At the same time, by utilizing the principle of countercurrent washing, the maximum utilization of water resources is achieved, and the consumption of fresh water and the generation of wastewater are reduced. In addition, the heat exchanger in the system can also heat or cool the washing water to adapt to the climatic conditions of different seasons and regions to ensure the stability of the purification effect. In summary, the purification system not only improves the purification efficiency of phosphogypsum, but also reduces environmental pollution, providing strong technical support for the resource utilization of phosphogypsum. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0017] Figure 2 It is a partial structural schematic diagram of the utility model.

[0018] The meaning of each number in the figure is:

[0019] 1. First reslurry tank; 2. First delivery pump; 3. Hydrocyclone; 4. Second reslurry tank; 5. Second delivery pump; 6. Slurry distribution box; 61. Dehydration zone; 62. First washing zone; 63. Second washing zone; 7. Heat exchanger; 8. Vacuum pump. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0021] The utility model provides a phosphogypsum deep countercurrent purification system, such as Figure 1-Figure 2 As shown, it includes a first re-slurry tank 1, and the phosphogypsum is flushed and re-slurried with production water. The bottom output end of the first re-slurry tank 1 is connected to the hydrocyclone 3 through a first delivery pump 2, and screening is performed through the hydrocyclone 3. A discharge port is arranged at the bottom of the hydrocyclone 3, and the discharge port is connected to the second re-slurry tank 4 through a pipeline. One side of the bottom of the second re-slurry tank 4 is connected to a slurry distribution box 6 through a second delivery pump 5 for uniform distribution. The interior of the slurry distribution box 6 is provided with a dehydration zone 61, a first washing zone 62 and a second washing zone 63 from left to right. The material is firstly dehydrated by vacuum filtration in the slurry distribution box 6, and then subjected to two countercurrent washings.

[0022] In this embodiment, an overflow port is provided at the top of the hydrocyclone 3, and the 500-mesh phosphogypsum and organic matter are sent to the phosphogypsum slag yard through the overflow. A discharge port is provided at the bottom, and the phosphogypsum sediment of the corresponding particle size is transported to the second re-slurry tank 4.

[0023] Specifically, the dehydration zone 61 is provided with a vacuum filter press chamber for vacuum filter press dehydration, and the first washing zone 62 and the second washing zone 63 are provided with a countercurrent washing chamber for countercurrent washing. The water content of the washed phosphogypsum is less than 23% after vacuum drying.

[0024] Furthermore, a heat exchanger 7 is provided outside the secondary washing area 63, the input end of the heat exchanger 7 is connected to the vacuum pump 8 through a pipeline, the output end of the heat exchanger 7 is connected to the secondary washing area 63 through a pipeline, and the input end of the vacuum pump 8 is connected to process water through a pipeline. The process water is used as the working fluid of the vacuum pump 8, and it also cools the gas while sealing the working chamber. The used process water is collected and heated by the heat exchanger 7 as the secondary washing water.

[0025] Furthermore, the bottom of the secondary washing zone 63 is connected to the top of the primary washing zone 62 through a pipeline for water flow transportation.

[0026] Furthermore, the bottom of a washing zone 62 is connected to the first reslurry tank 1 through a pipeline.

[0027] Furthermore, the bottom of the dehydration zone 61 is connected to an external production system through a pipeline.

[0028] Furthermore, the top of the dehydration zone 61 is connected to the output end of the second delivery pump 5 through a pipeline.

[0029] When the utility model is used, the phosphogypsum deep countercurrent purification system firstly rinses and re-pulps the phosphogypsum with production water in the first re-pulping tank; the re-pulped slurry is pumped into a hydrocyclone for screening, and the phosphogypsum and organic matter of 500 mesh are sent to the phosphogypsum slag yard through overflow, and the phosphogypsum sedimentation that meets the particle size is transported to the second re-pulping tank; the slurry in the second re-pulping tank is pumped into the slurry distribution box of the belt filter for uniform distribution; the slurry is first vacuum-filtered and dehydrated, and then subjected to two countercurrent washings; the washed phosphogypsum is vacuum-dried to a moisture content of less than 23%; the filtrate of the filter is sent to the phosphoric acid production system for use, the re-pulped slurry concentration of the first re-pulping tank is controlled at 20-40%, the phosphogypsum and organic matter of 500 mesh are sent to the phosphogypsum slag yard through overflow, and the re-pulped slurry concentration of the second re-pulping tank is controlled at 30-45%. The washing water from the first washing area 61 and the second washing area 62 is the process water supplemented with the working fluid of the vacuum pump, and then heated to 70-90°C by a heat exchanger as the second washing water. After washing, the second washing water is used as the first-stage washing water. The amount of washing water is 0.4-1 times the mass of phosphogypsum, which can save the use of process water and reduce operating costs.

[0030] The pressure of the dehydration zone 61 is 18-25 kPa, and the filtrate is sent back to the phosphoric acid production system to recover phosphorus and fluorine resources. After dehydration and washing, the water-soluble phosphorus of the phosphogypsum is less than 0.05%, the water-soluble fluorine is less than 0.03%, the whiteness is greater than 75, the content of calcium sulfate dihydrate (dry basis) is greater than 90%, the pH is greater than 5, and the moisture content of the phosphogypsum is less than 23%.

[0031] The above shows and describes the basic principle, main features and advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the utility model and are not used to limit the utility model. Without departing from the spirit and scope of the utility model, the utility model may have various changes and improvements, which fall within the scope of the utility model to be protected. The scope of protection of the utility model is defined by the attached claims and their equivalents.

Claims

1. A phosphogypsum deep countercurrent purification system, comprising a first reslurry tank (1), characterized in that: The bottom output end of the first reslurry tank (1) is connected to the hydrocyclone (3) via a first delivery pump (2); a discharge port is provided at the bottom of the hydrocyclone (3); the discharge port is connected to the second reslurry tank (4) via a pipeline; one side of the bottom of the second reslurry tank (4) is connected to a slurry distribution box (6) via a second delivery pump (5); a dehydration zone (61), a first washing zone (62) and a second washing zone (63) are provided in sequence from left to right inside the slurry distribution box (6).

2. The phosphogypsum deep countercurrent purification system according to claim 1, characterized in that: The top of the hydrocyclone (3) is provided with an overflow port, and the bottom is provided with a discharge port.

3. The phosphogypsum deep countercurrent purification system according to claim 1, characterized in that: The dehydration zone (61) is provided with a vacuum filter press chamber, and the first washing zone (62) and the second washing zone (63) are provided with a countercurrent washing chamber.

4. The phosphogypsum deep countercurrent purification system according to claim 3, characterized in that: A heat exchanger (7) is arranged outside the secondary washing zone (63); the input end of the heat exchanger (7) is connected to a vacuum pump (8) through a pipeline; the output end of the heat exchanger (7) is connected to the secondary washing zone (63) through a pipeline; and the input end of the vacuum pump (8) is connected to process water through a pipeline.

5. The phosphogypsum deep countercurrent purification system according to claim 3, characterized in that: The bottom of the secondary washing zone (63) is connected to the top of the primary washing zone (62) through a pipeline.

6. The phosphogypsum deep countercurrent purification system according to claim 3, characterized in that: The bottom of the first washing zone (62) is connected to the first reslurry tank (1) through a pipeline.

7. The phosphogypsum deep countercurrent purification system according to claim 3, characterized in that: The bottom of the dehydration zone (61) is connected to an external production system via a pipeline.

8. The phosphogypsum deep countercurrent purification system according to claim 1, characterized in that: The top of the dehydration zone (61) is connected to the output end of the second delivery pump (5) through a pipeline.

Images