A device and method for high-efficiency dechlorination of fly ash from waste incineration in a grate furnace by reverse water washing

Abstract

The invention discloses a device and method for reverse water washing and efficient dechlorination of fly ash from waste incineration in a grate furnace, comprising a fly ash feeder, a detachable tray, a water washing agitator, a primary water washing liquid storage tank and a clean water tank; the detachable tray is a group, which circulates between the fly ash feeder and the water washing agitator through a transportation mechanism, and the detachable tray can be detachably installed at the bottom of the water washing agitator; when the detachable tray moves to the bottom of the fly ash feeder, the fly ash to be washed is loaded into the detachable tray through the fly ash feeder; when the detachable tray moves to the bottom of the water washing agitator, it is installed with the bottom of the water washing agitator, and the fly ash in the detachable tray is washed by injecting water into the water washing agitator; the primary water washing liquid storage tank and the clean water tank are respectively connected to the water washing agitator through pipelines, and the water washing liquid is injected into the water washing agitator.

Description

Technical Field

[0001] The invention relates to the technical field of domestic waste incineration fly ash treatment, in particular to a device and method for reverse water washing and efficient dechlorination of fly ash from waste incineration in a grate furnace. Background Art

[0002] With the rapid development of urbanization and the improvement of people's living standards in my country, the amount of urban domestic waste has also increased rapidly. In 2018, the amount of urban domestic waste collected and transported nationwide reached 228.018 million tons. Domestic waste incineration has gradually become the mainstream method of domestic waste disposal in my country due to its advantages of significant reduction, less land occupation and energy conversion. The domestic waste incineration fly ash (hereinafter referred to as fly ash) produced is a powdery substance collected by the flue gas purification system of domestic waste incineration, which is a hazardous waste. In recent years, with the rapid growth of urban domestic waste generation, the amount of fly ash generated has become larger and larger. The relevant departments predict that by the end of the 13th Five-Year Plan, the annual fly ash generation in my country will reach 10 million tons. One of the major reasons for limiting the further treatment and disposal of fly ash is the high content of chlorine. Acidic substances such as hydrogen chloride generated by the incineration and decomposition of chlorine-containing plastics in domestic waste react with alkaline substances in the flue gas purification system to enter the fly ash, and salt in kitchen waste is also eventually enriched in fly ash. The fly ash composition produced by different municipal solid waste incinerators is also very different. Among them, the chlorine content in the fly ash of municipal solid waste incineration by grate furnace is the highest, with a chlorine content of more than 20%. The high chlorine content of fly ash greatly limits the subsequent treatment and deeper resource utilization, so an efficient water washing and dechlorination method for fly ash from grate furnace is urgently needed. Summary of the invention

[0003] Purpose of the invention: The technical problem to be solved by the present invention is to provide a device capable of realizing efficient dechlorination of fly ash from waste incineration in a grate furnace by reverse water washing in view of the deficiencies of the prior art. The technical problem to be further solved by the present invention is to provide a method for eluting chlorine from fly ash from waste incineration with high chlorine content in an efficient and environmentally friendly manner.

[0004] In order to solve the above technical problems, the present invention discloses a device for reverse water washing and efficient dechlorination of fly ash from waste incineration in a grate furnace, comprising a fly ash feeder, a detachable tray, a water washing agitator, a primary water washing liquid storage tank and a clean water tank;

[0005] The detachable tray is a group, which is cyclically moved between the fly ash feeder and the water-washing agitator through the transport mechanism, and the detachable tray can be detachably mounted on the bottom of the water-washing agitator;

[0006] When the detachable tray moves to the bottom of the fly ash feeder, the fly ash to be washed is loaded into the detachable tray through the fly ash feeder; when the detachable tray moves to the bottom of the water washing agitator, it is installed with the bottom of the water washing agitator, and the fly ash in the detachable tray is washed by injecting water into the water washing agitator;

[0007] The primary washing liquid storage tank and the clean water tank are respectively connected to the washing agitator through pipelines, and the washing liquid is injected into the washing agitator.

[0008] Specifically, the clean water tank is connected to the water supply port on the top of the water washing agitator through a water supply pipe, and the clean water in the clean water tank is supplied into the water washing agitator to perform primary cleaning on the fly ash;

[0009] The primary water washing liquid storage tank is connected to the water injection port on the top of the water washing agitator through a water injection pipe, and the primary fly ash water washing liquid in the primary water washing liquid storage tank is injected into the water washing agitator through the water injection pipe to wash the fly ash;

[0010] The bottom drain outlet of the water washing agitator is respectively connected to the primary water washing liquid storage tank and the external waste liquid storage tank through a drain pipe; after the clean water added into the water washing agitator is used to wash the fly ash, the primary fly ash water washing liquid formed is introduced into the primary water washing liquid storage tank through the drain pipe for storage; after the primary fly ash water washing liquid injected into the water washing agitator is used to wash the fly ash, the secondary fly ash water washing liquid formed is introduced into the external waste liquid storage tank through the drain pipe for subsequent treatment.

[0011] Specifically, the fly ash feeder is a cylindrical structure with a fly ash feeding port on the top and a fly ash feeding port on the bottom. A spray head is also provided at the bottom of the fly ash feeder, located outside the feeding port. When the fly ash feeder inputs fly ash into the detachable tray below, the spray head is turned on for spraying to prevent fly ash from raising dust.

[0012] Specifically, the water washing agitator comprises a barrel, a tray buckle, an agitator mounting seat and an agitator;

[0013] The bottom of the barrel body is open, and the tray buckles are evenly arranged on the outer edge of the bottom of the barrel body for connecting with the detachable tray buckle. The bottom inner wall of the barrel body is also provided with a sealing ring for sealing when the detachable tray is connected with the barrel body bottom buckle.

[0014] The agitator mounting seat is located on the top of the water washing agitator and is used to mount the agitator;

[0015] The agitator comprises a variable frequency agitator motor, a agitator shaft and agitator blades; the agitator shaft passes through the agitator mounting seat, and one end of the agitator shaft is connected to the output end of the variable frequency agitator motor, and the other end is connected to the agitator blades located in the barrel body.

[0016] Furthermore, the water washing agitator also includes a spoiler, a support ear and a pressure stabilizing port;

[0017] The spoiler is located on the inner wall of the barrel body, and is used to disturb the fly ash water washing liquid during the stirring process, so that the fly ash particles are fully dispersed and fully contact with the water washing liquid, thereby enhancing the dechlorination effect; the support ears are located on the outer wall of the barrel body, and are used to fix the water washing agitator; the pressure stabilizing port is arranged on the top of the barrel body, and is used to stabilize the internal pressure of the water washing agitator.

[0018] Specifically, a water replenishment pump is provided at the bottom of the clean water tank, which is connected to the water replenishment pipe, and the clean water in the clean water tank is replenished into the water washing agitator through the water replenishment pump.

[0019] Specifically, a water injection pump is provided at the bottom of the primary water washing liquid storage tank, which is connected to the water injection pipe, and the primary fly ash water washing liquid in the primary water washing liquid storage tank is injected into the water washing agitator through the water injection pump.

[0020] Furthermore, the present invention also provides a method for reversely washing fly ash from waste incineration in a grate furnace with the above device for efficient dechlorination, comprising the following steps:

[0021] S1: The fly ash to be washed is continuously loaded into a detachable tray through a fly ash feeder. The fly ash has a chlorine content of more than 20% from the waste incineration grate furnace.

[0022] S2: moving the detachable tray loaded with fly ash to the bottom of the water-washing agitator through a transport mechanism, and connecting and sealing the detachable tray to the bottom of the water-washing agitator;

[0023] S3: Adding primary water washing liquid into the water washing agitator through the primary water washing liquid storage tank, performing secondary water washing on the fly ash, allowing it to settle after water washing, and then draining the upper secondary water washing liquid through the pipeline;

[0024] S4: Add clean water into the washing agitator through the clean water tank to wash the fly ash with primary water, let it settle after washing, and then introduce the upper primary water washing liquid into the primary water washing liquid storage tank through a pipeline for storage, which is used as the primary water washing liquid for the next batch of fly ash in the detachable tray;

[0025] S5: The washed fly ash is transported to subsequent processing units through a transportation mechanism.

[0026] Preferably, in step S3 and step S4, the liquid-to-solid ratio of the secondary water washing and the primary water washing is controlled to be 3-5 mL / g, the stirring rate is controlled to be 270-450 r / min, the stirring and washing time is 10-25 min, and the static sedimentation time is 3-5 min.

[0027] Beneficial effects:

[0028] 1. The method of the present invention is applicable to fly ash from the incineration of domestic waste in a grate furnace. The chlorine content of such fly ash is about 20%, which is 3 to 4 times higher than that of the incineration of domestic waste in a fluidized bed. At the same time, it also contains a large amount of calcium and a small amount of heavy metals such as lead and copper, which greatly limits the further treatment and resource utilization of the fly ash.

[0029] 2. The present invention temporarily stores the primary washing liquid generated after washing with clean water in a storage tank, and uses it as the primary washing liquid of subsequent batches of fly ash, thereby achieving continuous operation and recycling of water resources, making full use of the solubility of water in chloride salts, and fully dissolving the washing liquid and fly ash multiple times, which can fully utilize water resources and elute the chloride salts in the fly ash into the washing liquid to the greatest extent.

[0030] 3. The method of the present invention can realize the flow line operation of fly ash washing through the transportation mechanism, which is suitable for industrialized amplification treatment and provides a new tool for waste incineration fly ash treatment. Through the method of the present invention, the dechlorination efficiency of grate furnace fly ash can be controlled to be above 80%, which provides great conditions for subsequent treatment. The used washing liquid can reach a basic saturation state, the chloride ion concentration can reach 50g / L, and the dechlorination efficiency utilization rate of water can reach above 90%. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more clear.

[0032] Figure 1 This is a schematic diagram of the overall structure of the device for reverse water washing and efficient dechlorination of fly ash from waste incineration in the grate furnace.

[0033] Figure 2 To study the changes in elemental composition of fly ash after one, two and three water washings using the device.

[0034] Among them, each figure mark represents: 1 fly ash feeder; 11 fly ash feeding port; 12 fly ash feeding port; 13 spray head; 2 detachable tray; 3 water washing agitator; 31 barrel; 32 tray buckle; 33 agitator mounting seat; 34 spoiler; 35 support ear; 36 pressure stabilizing port; 37 drain port; 38 water injection port; 39 water replenishment port; 4 primary water washing liquid storage tank; 5 clean water tank; 6 agitator; 61 variable frequency stirring motor; 62 agitator shaft; 63 stirring blades; 7 drain pipe; 71 external waste liquid storage tank; 8 water injection pump; 9 water injection pipe; 10 water replenishment pump; 14 water replenishment pipe. DETAILED DESCRIPTION

[0035] The present invention can be better understood with reference to the following examples.

[0036] The structures, proportions, sizes, etc. illustrated in the drawings of the specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical contents disclosed by the present invention. At the same time, the terms such as "upper", "lower", "front", "back", "middle" and so on quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the present invention without substantially changing the technical contents.

[0037] like Figure 1 As shown, the device for reverse water washing and efficient dechlorination of fly ash from waste incineration in a grate furnace mainly includes five parts: a fly ash feeder 1, a detachable tray 2, a water washing agitator 3, a primary water washing liquid storage tank 4 and a clean water tank 5.

[0038] The detachable tray 2 is a group, which circulates between the fly ash feeder 1 and the water-washing agitator 3 through a transport mechanism (which can be a common transport mechanism such as a belt conveyor), and the detachable tray 2 can be detachably installed at the bottom of the water-washing agitator 3. When the detachable tray 2 moves to the bottom of the fly ash feeder 1, the fly ash to be washed is loaded into the detachable tray 2 through the fly ash feeder 1; when the detachable tray 2 moves to the bottom of the water-washing agitator 3, it is installed with the bottom of the water-washing agitator 3, and the fly ash in the detachable tray 2 is washed by injecting water into the water-washing agitator 3;

[0039] The clean water tank 5 is connected to the water replenishment port 39 at the top of the water washing agitator 3 through the water replenishment pipe 14, and the clean water in the clean water tank 5 is replenished into the water washing agitator 3 to perform primary cleaning of the fly ash; the primary water washing liquid storage tank 4 is connected to the water injection port 38 at the top of the water washing agitator 3 through the water injection pipe 9, and the primary fly ash water washing liquid in the primary water washing liquid storage tank 4 is injected into the water washing agitator 3 through the water injection pipe 9 to clean the fly ash; the bottom drain port 37 of the water washing agitator 3 is connected to the primary water washing liquid storage tank 4 and the external waste liquid storage tank 71 through the drain pipe 7 respectively; after the clean water replenished in the water washing agitator 3 is used to wash the fly ash, the primary fly ash water washing liquid formed is introduced into the primary water washing liquid storage tank 4 through the drain pipe 7 for storage; after the primary fly ash water washing liquid injected into the water washing agitator 3 is used to wash the fly ash, the secondary fly ash water washing liquid formed is introduced into the external waste liquid storage tank 71 through the drain pipe 7 for subsequent treatment.

[0040] Among them, the fly ash feeder 1 is a cylindrical structure, with a fly ash feeding port 11 on the top and a fly ash feeding port 12 on the bottom; a spray head 13 is also provided at the bottom of the fly ash feeder 1, located outside the feeding port 12. When the fly ash feeder 1 inputs fly ash into the detachable tray 2 below, the spray head 13 is opened for spraying to prevent fly ash from raising dust.

[0041] The water-washing agitator 3 includes a barrel 31, a tray buckle 32, an agitator mounting seat 33 and an agitator 6; the barrel 31 is open at the bottom, and the tray buckles 32 are evenly arranged on the outer edge of the bottom of the barrel 31, which are used to be buckled and connected with the detachable tray 2. The bottom inner wall of the barrel 31 is also provided with a sealing ring, which is used to seal when the detachable tray 2 is buckled and connected with the bottom of the barrel 31. The agitator mounting seat 33 is located at the top of the water-washing agitator 3 and is used to install the agitator 6; the agitator 6 includes a variable frequency stirring motor 61, a stirring shaft 62 and a stirring blade 63; the stirring shaft 62 passes through the agitator mounting seat 33, and one end of the agitator shaft 62 is connected to the output end of the variable frequency stirring motor 61, and the other end is connected to the stirring blade 63 located in the barrel 31.

[0042] The water washing agitator 3 also includes a spoiler 34, a support ear 35 and a pressure stabilizing port 36; the spoiler 34 is located on the inner wall of the barrel body 31, and is used to disturb the fly ash water washing liquid during the stirring process, so that the fly ash particles are fully dispersed and fully contacted with the water washing liquid to enhance the dechlorination effect; the support ear 35 is located on the outer wall of the barrel body 31, and is used to fix the water washing agitator 3; the pressure stabilizing port 36 is arranged at the top of the barrel body 31, and is used to stabilize the internal pressure of the water washing agitator 3.

[0043] A water supply pump 10 is provided at the bottom of the clean water tank 5, which is connected to the water supply pipe 14. The clean water in the clean water tank 5 is supplied to the water washing agitator 3 through the water supply pump 10. A water injection pump 8 is provided at the bottom of the primary water washing liquid storage tank 4, which is connected to the water injection pipe 9. The primary fly ash water washing liquid in the primary water washing liquid storage tank 4 is injected into the water washing agitator 3 through the water injection pump 8.

[0044] The specific method of using the above device to reversely wash and efficiently dechlorinate fly ash from waste incineration in a grate furnace comprises the following steps:

[0045] S1: The fly ash to be washed is continuously loaded into the detachable tray 2 through the fly ash feeder 1, and the loading amount is 200g;

[0046] S2: moving the detachable tray 2 loaded with fly ash to the bottom of the water-washing agitator 3 by means of a transport mechanism, and connecting the detachable tray 2 to the bottom of the water-washing agitator 3 and sealing it;

[0047] S3: 800 mL of primary washing liquid is added into the washing agitator 3 through the primary washing liquid storage tank 4, and the fly ash is subjected to secondary washing. The stirring rate is controlled at 400 r / min, and the stirring washing time is 20 min. After washing, the mixture is allowed to stand and settle for 5 min, and then the upper layer of the secondary washing liquid is discharged through the pipeline;

[0048] S4: 800 mL of clean water is added to the washing stirrer 3 through the clean water tank 5 to perform primary washing of the fly ash. The stirring rate is controlled at 400 r / min, and the stirring and washing time is 20 min. After washing, the primary washing liquid is allowed to settle for 5 min, and then the upper primary washing liquid is introduced into the primary washing liquid storage tank 4 through a pipeline for storage, and is used as the primary washing liquid for the next batch of fly ash in the detachable tray 2;

[0049] S5: The washed fly ash is transported to subsequent processing units through a transportation mechanism.

[0050] When the machine is started for the first time, there is no primary washing liquid stored in the primary washing liquid storage tank 4, so it is necessary to continuously add clean water into the washing agitator 3 twice to perform two primary washings, and the generated primary washing liquid is introduced into the washing liquid storage tank 4 for storage.

[0051] The fly ash with a moisture content of 1.96% was washed with water using the above device. The first washing used a primary washing liquid, the second washing used clean water, and the third washing still used clean water. This can simulate the effect of continuous operation of the device. The components of the washing liquid and fly ash and the washing effect tend to be stable. The mass loss of fly ash after washing can reach 30%. According to the test, the efficiency of fly ash water washing dechlorination by this method reached 83.4%, and the dechlorination effect was good. The dechlorination effect is as follows Figure 2 As shown, it can be seen that the chlorine content of chlorine (the first gray grid on the left) after the second washing is much lower than that of the original fly ash, and the three clean water washings after the second washing have little effect on the dechlorination of the fly ash. Therefore, this experiment proves that only two washings are needed to achieve a good dechlorination effect. At the same time, the heavy metal content in the secondary washing liquid produced by the two-stage washing with different liquid-to-solid ratios is shown in Table 1. Compared with the water quality standard B for sewage discharged into the urban sewer, only the concentration of lead exceeds the standard, and the others meet the standard.

[0052] Table 1

[0053]

[0054] The present invention provides a device and method for reverse water washing of fly ash from waste incineration in a grate furnace for efficient dechlorination. There are many methods and ways to implement the technical solution. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention. All components not specified in this embodiment can be implemented by existing technologies.

Claims

1. A device for reverse water washing and efficient dechlorination of fly ash from waste incineration in a grate furnace, characterized in that: It comprises a fly ash feeder (1), a detachable tray (2), a water washing agitator (3), a primary water washing liquid storage tank (4) and a clean water tank (5); The detachable tray (2) is a group, which is cyclically moved between the fly ash feeder (1) and the water-washing agitator (3) by a transport mechanism, and the detachable tray (2) can be detachably mounted on the bottom of the water-washing agitator (3); When the detachable tray (2) moves to the bottom of the fly ash feeder (1), the fly ash to be washed is loaded into the detachable tray (2) through the fly ash feeder (1); when the detachable tray (2) moves to the bottom of the water-washing agitator (3), it is installed with the bottom of the water-washing agitator (3), and the fly ash in the detachable tray (2) is washed by water by injecting water into the water-washing agitator (3); The primary washing liquid storage tank (4) and the clean water tank (5) are respectively connected to the washing agitator (3) through pipelines, and the washing liquid is injected into the washing agitator (3); The clean water tank (5) is connected to the water supply port (39) at the top of the water-washing agitator (3) via a water supply pipe (14), and the clean water in the clean water tank (5) is supplied to the water-washing agitator (3) to perform primary cleaning on the fly ash; The primary water washing liquid storage tank (4) is connected to the water injection port (38) at the top of the water washing agitator (3) via a water injection pipe (9), and the primary fly ash water washing liquid in the primary water washing liquid storage tank (4) is injected into the water washing agitator (3) via the water injection pipe (9) to wash the fly ash; The bottom drain port (37) of the water-washing agitator (3) is connected to the primary water-washing liquid storage tank (4) and the external waste liquid storage tank (71) respectively through a drain pipe (7); after the clean water added to the water-washing agitator (3) is used to wash the fly ash, the primary fly ash water-washing liquid formed is introduced into the primary water-washing liquid storage tank (4) through the drain pipe (7) for storage; after the primary fly ash water-washing liquid injected into the water-washing agitator (3) is used to wash the fly ash, the secondary fly ash water-washing liquid formed is introduced into the external waste liquid storage tank (71) through the drain pipe (7) for subsequent treatment; The fly ash feeder (1) is a cylindrical structure, with a fly ash feeding port (11) provided at the top and a fly ash feeding port (12) provided at the bottom; a spray head (13) is also provided at the bottom of the fly ash feeder (1) and outside the feeding port (12).

2. According to the device for reverse water washing and efficient dechlorination of fly ash from waste incineration in a grate furnace according to claim 1, the water washing agitator (3) comprises a barrel (31), a tray buckle (32), an agitator mounting seat (33) and an agitator (6); The bottom of the barrel body (31) is open, and the tray buckles (32) are evenly arranged on the outer edge of the bottom of the barrel body (31) for buckling with the detachable tray (2), and the bottom inner wall of the barrel body (31) is also provided with a sealing ring; The agitator mounting seat (33) is located on the top of the water washing agitator (3) and is used for mounting the agitator (6); The stirrer (6) comprises a variable frequency stirring motor (61), a stirrer shaft (62) and a stirring blade (63); the stirrer shaft (62) passes through the stirrer mounting seat (33), and one end of the stirrer shaft (62) is connected to the output end of the variable frequency stirring motor (61), and the other end is connected to the stirring blade (63) located in the barrel (31).

3. According to the device for reverse water washing and efficient dechlorination of fly ash from waste incineration in a grate furnace as described in claim 2, the water washing agitator (3) further comprises a spoiler (34), a support ear (35) and a pressure stabilizing port (36); The spoiler (34) is located on the inner wall of the barrel body (31); the support ear (35) is located on the outer wall of the barrel body (31); and the pressure stabilizing port (36) is arranged on the top of the barrel body (31).

4. According to the device for reverse water washing and efficient dechlorination of fly ash from waste incineration in a grate furnace as described in claim 1, a water supply pump (10) is provided at the bottom of the clean water tank (5), which is connected to a water supply pipe (14), and the clean water in the clean water tank (5) is replenished into the water washing agitator (3) through the water supply pump (10).

5. According to the device for reverse water washing and efficient dechlorination of fly ash from waste incineration in a grate furnace as described in claim 1, a water injection pump (8) is provided at the bottom of the primary water washing liquid storage tank (4), which is connected to a water injection pipe (9), and the primary fly ash water washing liquid in the primary water washing liquid storage tank (4) is injected into the water washing agitator (3) through the water injection pump (8).

6. A method for efficiently dechlorinating fly ash from waste incineration in a grate furnace by reverse water washing using the device of claim 1, characterized in that: The steps include: S1: grate furnace waste incineration fly ash with a fly ash chlorine content of more than 20% is continuously loaded into a detachable tray (2) through a fly ash feeder (1); S2: moving the detachable tray (2) loaded with fly ash to the bottom of the water-washing agitator (3) by means of a transport mechanism, and connecting and sealing the detachable tray (2) and the bottom of the water-washing agitator (3); S3: replenishing the primary washing liquid into the washing agitator (3) through the primary washing liquid storage tank (4), performing secondary washing on the fly ash, allowing it to settle after washing, and then draining the upper secondary washing liquid through a pipeline; S4: adding clean water into the washing agitator (3) through the clean water tank (5) to perform primary washing on the fly ash, and then allowing the fly ash to settle after washing. Then, the upper primary washing liquid is introduced into the primary washing liquid storage tank (4) through a pipeline for storage, and is used as the primary washing liquid for the next batch of fly ash in the detachable tray (2); S5: The washed fly ash is transported to subsequent processing units through a transportation mechanism.

7. The method for high-efficiency dechlorination of fly ash from waste incineration in a grate furnace by reverse water washing according to claim 6, characterized in that: In step S3 and step S4, the liquid-to-solid ratio of the secondary water washing and the primary water washing is controlled to be 3-5 mL / g, the stirring rate is controlled to be 270-450 r / min, the stirring and washing time is 10-25 min, and the static sedimentation time is 3-5 min.

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