A filler for intercepting suspended solids in desulfurization wastewater, its preparation method and application

Abstract

The present invention discloses a filler for intercepting suspended solids in desulfurized wastewater, its preparation method and application. Through the improvement of the filler components and preparation method, the filler has excellent mechanical strength and stable chemical properties, can withstand the high-salt and highly corrosive water environment of desulfurized wastewater, and is not easily deformed or damaged due to mutual friction during regeneration, thus avoiding losses. When the filler is used as the filter bed layer of the filtration device, after the desulfurized wastewater is pretreated, the reduction rate of suspended solids can reach 95%, and the pretreatment time can be shortened to 5-10 minutes, greatly improving the pretreatment efficiency of desulfurized wastewater. The desulfurized wastewater pretreatment process provided by the present invention has higher pretreatment efficiency and better treatment effect compared with the traditional pretreatment method of the pre-sedimentation tank, can greatly improve the operation efficiency of the triple box, and further reduce the chemical dosage of the triple box.

Description

Technical Field

[0001] The present invention belongs to the technical field of desulfurized wastewater treatment, and particularly relates to a particle for intercepting suspended substances in desulfurized wastewater, a preparation method thereof, and an application thereof. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the overall understanding of the present invention, and it is not necessarily regarded as an admission or any form of implication that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] Desulfurized wastewater is the end wastewater of a power plant. The smooth treatment of desulfurized wastewater is directly related to the stable operation of the entire power plant wastewater treatment system and directly related to whether the environmental protection indicators of the entire power plant can meet the standards. Usually, the treatment of desulfurized wastewater adopts a triple-tank process, that is, the pH of the desulfurized wastewater is adjusted, heavy metals are removed, and flocculation and sedimentation treatment are carried out successively. However, due to the large content of suspended substances in desulfurized wastewater and most of them are particles with a relatively large surface viscosity, blockages often occur in the pipes and tanks, affecting the normal operation of the triple tank.

[0004] Establishing a fast and efficient pre-sedimentation process is an important step to ensure the subsequent treatment of desulfurized wastewater. In the prior art, the pre-sedimentation treatment of desulfurized wastewater is usually achieved by adding a sedimentation tank, but this treatment method requires a large floor area and will seriously affect the sedimentation effect when the water volume changes. Therefore, how to achieve the efficient pretreatment of desulfurized wastewater, avoid blockages when treating wastewater in the triple tank, and ensure the stable treatment process of desulfurized wastewater is a technical problem that needs to be solved urgently at present. Summary of the Invention

[0005] In order to solve the deficiencies of the prior art, the present invention provides a filler for intercepting suspended substances in desulfurized wastewater, a preparation method thereof, and an application thereof. By synthesizing a highly stable filler with extremely strong affinity for suspended substances, and using this filler as a filter bed layer to remove the suspended substances in desulfurized wastewater, the pretreatment of desulfurized wastewater is realized, and blockages during the treatment of wastewater in the triple tank are avoided.

[0006] Specifically, the present invention is realized through the following technical solutions:

[0007] In the first aspect of the present invention, there is provided a filler for intercepting suspended substances in desulfurized wastewater, including calcium sulfate, aluminum oxide, calcium oxide, and iron powder. Among them, the mass ratio of calcium sulfate, aluminum oxide, and calcium oxide is 4.5 - 5.5:2 - 4:0.5 - 1.5, and the mass ratio of iron powder to the mixed powder of calcium sulfate, aluminum oxide, and calcium oxide is 1:50 - 70.

[0008] Furthermore, the purity of each component of calcium sulfate, aluminum oxide, calcium oxide, and iron powder is higher than 99%.

[0009] Further, the filler has a diameter of 2 - 3 cm.

[0010] In the second aspect of the present invention, a method for preparing a filler for intercepting suspended solids in desulfurized wastewater is provided. Calcium sulfate, aluminum oxide, calcium oxide, and iron powder are put into a ball mill for grinding and mixing, and the powder passing through a 200 - mesh sieve is taken. Using the dry - pressing method, the mixed powder is pressed into small balls with a diameter of 2 - 3 cm. Then, the small balls are put into a muffle furnace for calcination. After calcination, the small balls are put into a grinding machine for grinding, and after being rinsed with water, the filler for efficiently intercepting suspended solids in desulfurized wastewater is obtained.

[0011] Further, first, calcium sulfate, aluminum oxide, and calcium oxide are ground and mixed according to a mass ratio of 4.5 - 5.5:2 - 4:0.5 - 1.5, and then iron powder is uniformly mixed with the mixed powder of calcium sulfate, aluminum oxide, and calcium oxide according to a mass ratio of 1:50 - 70. Preferably, the mass ratio of calcium sulfate, aluminum oxide, and calcium oxide is 5:3:1, and the mass ratio of iron powder to the mixed powder of calcium sulfate, aluminum oxide, and calcium oxide is 1:60.

[0012] Further, when calcining in the muffle furnace, the calcination temperature is 500 - 700 °C, the calcination time is 2 - 4 h, and the heating rate is 4 - 7 °C / min. Preferably, the calcination temperature is 600 °C, the calcination time is 3 h, and the heating rate is 4 °C / min.

[0013] In the third aspect of the present invention, a filtering device is provided, which includes a filler tank. The filler described in the first aspect is filled in the filler tank to form a filtering bed layer, and a filter screen is arranged at the top of the filtering bed layer.

[0014] Further, the height of the filtering bed layer is not less than 1 m.

[0015] In the fourth aspect of the present invention, a desulfurized wastewater pretreatment process is provided. Before the desulfurized wastewater is treated, it first enters the filtering device for pretreatment. Under the action of the filtering bed layer of the filtering device, the suspended solids in the desulfurized wastewater are removed, and the desulfurized wastewater with suspended solids removed enters the triple - box for subsequent treatment.

[0016] Further, two filtering devices are arranged in parallel in a one - use - one - standby mode. When the water flux of one of the filtering devices drops below 50% of the initial water volume, the other filtering device is used for filtration; the filler in the filtering device with the decreased water flux is sent to a cleaning tank for cleaning, and after cleaning, it is backfilled into the filtering device.

[0017] One or more embodiments of the present invention have the following beneficial effects:

[0018] (1) The filter bed filler of the present invention has excellent mechanical strength, stable chemical properties, and can withstand the high-salt and highly corrosive water environment of desulfurization wastewater. During regeneration, it is not easy for the filler to be deformed or damaged due to mutual friction, thereby causing loss;

[0019] (2) After the filter bed of the present invention pre-treats the desulfurization wastewater, the suspended solids reduction rate can reach 95%, and the pre-treatment time can be shortened to 5-10 minutes, greatly improving the desulfurization wastewater pre-treatment efficiency;

[0020] (3) The catalytic bed of the present invention has a large particle size of fillers, so that the gaps between the fillers are large, and the pressure drop of the desulfurized wastewater passing through the bed is small. The pretreatment of the desulfurized wastewater does not rely entirely on the physical interception of the filter bed, but also relies on the adsorption effect of the filler surface on small suspended particles in the desulfurized wastewater. Therefore, it is not easy to cause problems such as pressure build-up;

[0021] (4) The catalytic bed regeneration process of the present invention adopts a method of first dispersing and then washing the filler. The cleaning process is thorough and the bed flux recovery effect is good. Compared with the backwashing method, the cleaning effect is better and the flux recovery effect is better;

[0022] (5) Compared with the pretreatment method of the traditional pre-sedimentation tank, the desulfurization wastewater pretreatment process of the present invention has higher pretreatment efficiency and better treatment effect, can greatly improve the operating efficiency of the triple box, increase the operating cycle of the triple box, and also reduce the dosage of the triple box. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein:

[0024] Figure 1 This is a process flow chart of the desulfurization wastewater pretreatment process of the present invention;

[0025] Figure 2 It is a schematic diagram of the structure of the filtering device of the present invention;

[0026] Among them, 1. desulfurization wastewater, 2. water flow switch, 3. triple box, 4. filter bed, 5. cleaning tank, 6. cleaning water inlet, 7. cleaning wastewater discharge port; 8. packing inlet of the cleaning tank; 9. packing outlet of the cleaning tank; 10. filtering device, 12. desulfurization wastewater inlet, 13. desulfurization wastewater outlet, 14. packing inlet of the filtering device, 15. packing outlet of the filtering device. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. The experimental methods without specific conditions noted in the following embodiments are generally carried out under conventional conditions or according to the conditions recommended by the manufacturer.

[0028] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0029] In the prior art, the pre-sedimentation treatment of desulfurized wastewater is usually achieved by setting up sedimentation tanks. However, sedimentation tanks require a large floor area, and the sedimentation effect will be seriously affected when the water volume changes. The suspended solids in desulfurized wastewater mainly include gypsum particles, silica, and hydroxides of iron and aluminum. Therefore, according to the components of the suspended solids in desulfurized wastewater, the present invention synthesizes a highly stable filler with extremely strong affinity for suspended solids, forms a fixed-bed filter layer with the highly stable filler, and conducts efficient filtration treatment on desulfurized wastewater. Regularly adopting the method of dispersedly cleaning the filter layer filler to restore the water flux of the filter layer, ensuring the efficient pretreatment of desulfurized wastewater, laying an important foundation for the stable operation of the triple box, and ensuring the stable treatment process of desulfurized wastewater.

[0030] In one or more embodiments of the present invention, a filler for intercepting suspended solids in desulfurized wastewater is provided, and its components include calcium sulfate, aluminum oxide, calcium oxide, and iron powder. Among them, the mass ratio of calcium sulfate, aluminum oxide, and calcium oxide is 4.5 - 5.5:2 - 4:0.5 - 1.5. Since the main component of the suspended solids in desulfurized wastewater is calcium sulfate, choosing calcium sulfate as the main component is beneficial to the coagulation of suspended solids. Aluminum oxide and calcium oxide are structure regulators. Aluminum oxide is beneficial to the ductility of particles, making the particles not easily broken during the mixing and transfer process. Calcium oxide increases the particle hardness, making the bottom particles not easily crushed. Iron powder is an adhesive, enabling the particles to be sintered at a lower calcination temperature. Therefore, the filler composed of these four components has extremely strong stability, has a good interception effect on the suspended solids in desulfurized wastewater, and is not easily worn.

[0031] The mass ratio of iron powder to the mixed powder of calcium sulfate, aluminum oxide, and calcium oxide is 1:50 - 70, preferably 1:60. The reason for controlling the iron powder within this range is that if the iron powder content is too low, the particles are not easily sintered; if the iron powder content is too high, the sintering degree is too high, and it is easy to melt and will not form particles.

[0032] Furthermore, the purity of each component of calcium sulfate, aluminum oxide, calcium oxide, and iron powder is higher than 99%, which can give full play to the functions of each component and avoid the influence of impurities contained in the components on the physical and chemical properties of the particles, so as to ensure the stability of the prepared filler.

[0033] Furthermore, the diameter of the filler is 2 - 3 cm. When the filler particles are too large, the gaps between the fillers are too large, and the filtration effect of the suspended matter is not good. When the filler particles are too small, the gaps between the fillers are too small, and the water flux drops rapidly during use, requiring multiple cleanings. Controlling the filler particle size within 2 - 3 cm can effectively ensure the interception effect on the suspended matter in the desulfurization wastewater.

[0034] In one or more embodiments of the present invention, a method for preparing a filler for intercepting suspended matter in desulfurization wastewater is provided. Calcium sulfate, aluminum oxide, calcium oxide, and iron powder are put into a ball mill according to a ratio for grinding and mixing. The powder passing through a 200 - mesh sieve is taken to remove larger particles to improve the stability of the prepared filler. The dry - pressing method is used to press the mixed powder into small balls with a diameter of 2 cm. Then, the small balls are put into a muffle furnace for calcination. When calcining in the muffle furnace, the calcination temperature is 500 - 700 °C, the calcination time is 2 - 4 h, and the heating rate is 4 - 7 °C / min. After calcination, the small balls are put into a grinding machine for grinding to separate the un - sintered parts on the surface of the small balls. After washing with water, a filler for efficiently intercepting suspended matter in desulfurization wastewater is obtained.

[0035] Furthermore, first, calcium sulfate, aluminum oxide, and calcium oxide are ground and mixed according to a mass ratio of 4.5 - 5.5:2 - 4:0.5 - 1.5, and then iron powder is uniformly mixed with the mixed powder of calcium sulfate, aluminum oxide, and calcium oxide according to a mass ratio of 1:50 - 70. Preferably, the mass ratio of calcium sulfate, aluminum oxide, and calcium oxide is 5:3:1, and the mass ratio of iron powder to the mixed powder of calcium sulfate, aluminum oxide, and calcium oxide is 1:60.

[0036] Preferably, the calcination temperature is 600 °C, the calcination time is 3 h, and the heating rate is 4 °C / min.

[0037] The filler prepared by this preparation method has stable chemical and physical properties, is not easily corroded or damaged by desulfurization wastewater, and is not easily deformed or lost due to mutual friction or hydraulic scouring.

[0038] In one or more embodiments of the present invention, as Figure 1 and Figure 2 shown, a filtering device is provided, including a filler tank filled with the above - mentioned filler to form a filter bed layer 4. A filter screen is arranged at the top of the filter bed layer, and the height of the filter bed layer is not less than 1 m so that the suspended matter in the desulfurization wastewater can be effectively filtered.

[0039] A desulfurization wastewater inlet 12, a desulfurization wastewater outlet 13, a packing inlet 14 of the filtering device, and a packing outlet 15 of the filtering device are arranged on the filtering device; after the filtering device operates for a period of time, the pores between the packings are gradually filled with suspended matters, resulting in a decrease in water flux. When the water flux drops below 50% of the original flux, at this time, it is necessary to wash the filter bed layer of the filtering device. The packing outlet 15 of the filtering device is connected to the packing inlet 8 of the cleaning tank. Compressed air is used to transport the packings in the filter bed layer to the cleaning tank 5 for cleaning, and compressed air is used as the auxiliary power for cleaning to achieve turbulent washing of the small balls in the cleaning tank. The packing inlet 14 of the filtering device is connected to the packing outlet 9 of the cleaning tank. The washed packings are sent to the filtering device by compressed air for reuse, improving the utilization rate of the packings.

[0040] In one or more embodiments of the present invention, for a desulfurization wastewater pretreatment process, the desulfurization wastewater 1 enters the filtering device 10 first before being treated. Under the action of the filter bed layer 4 of the filtering device 10, the suspended matters in the desulfurization wastewater are removed, and the desulfurization wastewater from which the suspended matters are removed enters the triple box for subsequent treatment.

[0041] Furthermore, two filtering devices are arranged in parallel, one for use and one for standby. When the water flux of one of the filtering devices drops below 50% of the initial water volume, the other filtering device is used for filtration. A water flow switch 2 is arranged between the two filtering devices, and the working states of the two filtering devices are switched through the water flow switch; the packings in the filtering device with a decreased water flux are sent to the cleaning tank 5 for cleaning, and after cleaning, they are backfilled into the filtering device 10.

[0042] The cleaning tank uses water to clean the packings. Therefore, a cleaning water inlet 6 and a cleaning wastewater discharge port 7 are arranged on the cleaning tank.

[0043] The following further elaborates on the present invention with specific embodiments. It should be noted that the specific embodiments are explanations rather than limitations of the present invention.

[0044] Embodiment 1

[0045] A packing for intercepting suspended matters in desulfurization wastewater, whose components include calcium sulfate, aluminum oxide, calcium oxide, and iron powder. Among them, the mass ratio of calcium sulfate, aluminum oxide, and calcium oxide is 5:3:1, and the mass ratio of iron powder to the mixed powder of calcium sulfate, aluminum oxide, and calcium oxide is 1:60. The purity of each component of calcium sulfate, aluminum oxide, calcium oxide, and iron powder is higher than 99%. The diameter of the packing is 2 cm;

[0046] The preparation method is as follows:

[0047] Put calcium sulfate, alumina, calcium oxide, and iron powder into a ball mill for grinding and mixing according to a mass ratio of 5:3:1. Then, mix the iron powder with the mixed powder of calcium sulfate, alumina, and calcium oxide at a ratio of 1:60. Take the powder smaller than 200 mesh, press the mixed powder into small balls with a diameter of 2 cm, and then put them into a muffle furnace for calcination. The calcination temperature is 600 °C, the calcination time is 3 h, and the heating rate is 4 °C / min. After calcination, put the filler into a grinding machine for grinding, separate the un-sintered part on the surface of the filler, and wash it with water to obtain the filler.

[0048] Use this filler as the filter bed layer of the filtration device. The height of the bed layer is set to 1 m, and the desulfurized wastewater of Huadian Jining Power Plant is pretreated. The lime addition amount is 68 ppm, the organic sulfur addition amount is 30 ppm, the flocculant addition amount is 15 ppm. The suspended solid content in the treated desulfurized wastewater is 0.21%, and the operation cycle of the triple box is 70 days.

[0049] Example 2

[0050] The difference from Example 1 is that the desulfurized wastewater of Huadian Xindian Power Plant is pretreated. The lime addition amount is 57 ppm, the organic sulfur addition amount is 15 ppm, the flocculant addition amount is 15 ppm. The suspended solid content in the treated desulfurized wastewater is 0.15%, and the operation cycle of the triple box is 80 days.

[0051] Example 3

[0052] The difference from Example 1 is that the desulfurized wastewater of Huadian Canal Power Plant is pretreated. The lime addition amount is 55 ppm, the organic sulfur addition amount is 15 ppm, the flocculant addition amount is 15 ppm. The suspended solid content in the treated desulfurized wastewater is 0.18%, and the operation cycle of the triple box is 70 days.

[0053] Example 4

[0054] The difference from Example 1 is that the desulfurized wastewater of Huadian Huangtai Power Plant is pretreated. The lime addition amount is 65 ppm, the organic sulfur addition amount is 20 ppm, the flocculant addition amount is 15 ppm. The suspended solid content in the treated desulfurized wastewater is 0.15%, and the operation cycle of the triple box is 80 days.

[0055] Example 5

[0056] Differences from Example 1: The desulfurized wastewater of Huaneng Jiaxiang Power Plant is pretreated. Before treatment, the desulfurized wastewater enters the filtration device. Under the action of the filter bed layer of the filtration device, the suspended solids in the desulfurized wastewater are removed. The desulfurized wastewater with suspended solids removed enters the triple box for subsequent treatment. The lime addition amount is 55 ppm, the organic sulfur addition amount is 15 ppm, the flocculant addition amount is 15 ppm. The suspended solid content in the treated desulfurized wastewater is 0.21%, and the operation cycle of the triple box is 70 days.

[0057] Comparative Example 1

[0058] Differences from Example 1: A filler with a diameter of 5 cm is used as the filter bed layer to pretreat the desulfurized wastewater of Huaneng Xindian Power Plant. The lime addition amount is 75 ppm, the organic sulfur addition amount is 10 ppm, the flocculant addition amount is 15 ppm. The suspended solid content in the treated desulfurized wastewater is 2.9%, and the operation cycle of the triple box is 45 days.

[0059] Comparative Example 2

[0060] Differences from Example 1: The bed height is 0.2 m to pretreat the desulfurized wastewater of Huaneng Jining Canal Power Plant. The chemical addition amounts are the same as those in Example 3. Specifically, the lime addition amount is 95 ppm, the organic sulfur addition amount is 15 ppm, the flocculant addition amount is 25 ppm. The suspended solid content in the treated desulfurized wastewater is 4.2%, and the operation cycle of the triple box is 25 days.

[0061] Comparative Example 3

[0062] Differences from Example 1: Ordinary anthracite fillers with the same particle size are used as the filter bed layer of the filtration device to pretreat the desulfurized wastewater of Huaneng Jining Power Plant. The lime addition amount is 68 ppm, the organic sulfur addition amount is 30 ppm, the flocculant addition amount is 15 ppm. The suspended solid content in the treated desulfurized wastewater is 4.7%, and the operation cycle of the triple box is 25 days.

[0063] Comparative Example 4

[0064] A sedimentation tank is used to pretreat the desulfurized wastewater of Huaneng Jining Power Plant. The lime addition amount is 68 ppm, the organic sulfur addition amount is 30 ppm, the flocculant addition amount is 15 ppm. The suspended solid content in the treated desulfurized wastewater is 4.7%, and the operation cycle of the triple box is 35 days.

[0065] By analyzing the data of the suspended solid content, chemical addition amounts, and the operation cycle of the triple box in the above examples and comparative examples, the following conclusions can be drawn:

[0066] (1) The present invention has a good pretreatment effect on the pretreatment of desulfurized wastewater generated by different power plants, which can effectively reduce the suspended solids in the desulfurized wastewater, avoid blockage during the treatment of wastewater in the triple box, and at the same time reduce the usage amount of chemicals (such as lime, organic sulfur, flocculant), increase the operation cycle of the triple box, and improve the operation stability of the triple box.

[0067] (2) Compared with the existing fillers, the filler of the present invention can effectively reduce the content of suspended solids in the desulfurized wastewater, and the triple box has a long operation cycle, avoiding blockage during the treatment of wastewater in the triple box and improving the operation stability of the triple box;

[0068] (3) Compared with the existing desulfurized wastewater treatment process in the sedimentation tank, the desulfurized wastewater pretreatment process of the present invention can effectively reduce the content of suspended solids, increase the operation cycle of the triple box, and improve the operation stability of the triple box.

[0069] (4) The size of the filler has an important impact on the filtration effect. When the filler is too large and the gap between the fillers is too large, the filtration effect and adsorption effect on the suspended solids in the desulfurized wastewater will become poor, resulting in ineffective filtration of some suspended solids in the desulfurized wastewater, which will affect the operation cycle of the triple box; at the same time, the height of the filter bed layer in the filtration device has an important impact on the filtration effect. When the filter bed layer is less than 1 m, it means that there is too little filler in the filtration device. When the desulfurized wastewater flows through the filter bed layer, some suspended solids cannot be effectively filtered, and the too small height of the bed layer will cause the water flux to drop rapidly and shorten the cleaning cycle.

[0070] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent substitution on some of the technical features. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A filler for intercepting suspended solids in desulfurization wastewater, characterized in that, It includes calcium sulfate, aluminum oxide, calcium oxide, and iron powder. Among them, the mass ratio of calcium sulfate, aluminum oxide, and calcium oxide is 4.5 - 5.5:2 - 4:0.5 - 1.5, and the mass ratio of iron powder to the mixed powder of calcium sulfate, aluminum oxide, and calcium oxide is 1:50 - 70; Grind and mix calcium sulfate, aluminum oxide, calcium oxide, and iron powder, take the powder smaller than 200 mesh, and use the dry pressing method to press the mixed powder into small balls with a diameter of 2 - 3 cm; conduct calcination, the calcination temperature is 500 - 700 °C, the calcination time is 2 - 4 h, and after calcination, put the small balls into a grinding machine for grinding, and then wash with water to obtain the filler for efficiently intercepting suspended solids in desulfurized wastewater.

2. The filler for intercepting suspended solids in desulfurization wastewater according to claim 1, characterized in that, The purity of each component of calcium sulfate, aluminum oxide, calcium oxide, and iron powder is higher than 99%.

3. The filler for intercepting suspended solids in desulfurization wastewater according to claim 1, characterized in that, The diameter of the filler is 2 - 3 cm.

4. A preparation method of the filler for intercepting suspended solids in desulfurization wastewater according to claim 1, characterized in that, During grinding, first grind and mix calcium sulfate, aluminum oxide, and calcium oxide according to the mass ratio of 4.5 - 5.5:2 - 4:0.5 - 1.5, and then uniformly mix iron powder with the mixed powder of calcium sulfate, aluminum oxide, and calcium oxide according to the mass ratio of 1:50 - 70.

5. The preparation method of the filler for intercepting suspended solids in desulfurization wastewater according to claim 1, characterized in that, The mass ratio of calcium sulfate, aluminum oxide, and calcium oxide is 5:3:1, and the mass ratio of iron powder to the mixed powder of calcium sulfate, aluminum oxide, and calcium oxide is 1:

60.

6. The preparation method of the filler for intercepting suspended solids in desulfurization wastewater according to claim 1, characterized in that, The heating rate is 4 - 7 °C / min.

7. The preparation method of the filler for intercepting suspended solids in desulfurization wastewater according to claim 1, characterized in that, The calcination temperature is 600 °C, the calcination time is 3 h, and the heating rate is 4 °C / min.

8. A filtering device, characterized in that, It includes a filler tank, and the filler tank is filled with the filler described in any one of claims 1 - 3 to form a filter bed layer, and a filter screen is arranged at the top of the filter bed layer.

9. The filtering device according to claim 8, characterized in that, The height of the filter bed layer is not less than 1 m.

10. A desulfurization wastewater pretreatment process, implemented by using the filtering device according to claim 8 or 9, characterized in that, Before the desulfurized wastewater is treated, it first enters a filtering device for pretreatment. Under the action of the filter bed layer of the filtering device, the suspended solids in the desulfurized wastewater are removed, and the desulfurized wastewater with the suspended solids removed enters a triple box for subsequent treatment.

11. The desulfurization wastewater pretreatment process according to claim 10, characterized in that, Two filtering devices are arranged in parallel, one for use and one for standby. When the water flux of one filtering device drops below 50% of the initial water volume, the other filtering device is used for filtration; the filler in the filtering device with the decreased water flux is sent to a cleaning tank for cleaning, and after cleaning, it is backfilled into the filtering device.

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