Pretreated waste incineration fly ash washing wastewater treatment system

Abstract

The utility model relates to the field of wastewater treatment, in particular to a system for treating pretreated waste incineration fly ash washing wastewater. Comprising a fly ash temporary storage bin, a fly ash conveying system, a fly ash pre-dissolving tank, a fly ash washing system, a first solid-liquid separation device, a second solid-liquid separation device, a raw water pool, a hardness removal system, a second solid-liquid separation device, a COD (Chemical Oxygen Demand) removal system, a pH (Potential of Hydrogen) adjusting system, filtering equipment and evaporative crystallization equipment, the fly ash washing system is used for treating the slurry output by the fly ash pre-dissolving tank, so that heavy metal in the slurry is stabilized in the slurry, metal salt is washed out, and a first mud-water mixture is finally obtained; the slurry output by the fly ash pre-dissolving tank can be treated through the fly ash washing system, so that heavy metals in the slurry are stabilized in the slurry, the construction cost and the treatment cost of subsequent wastewater treatment are reduced, the risk caused by hazardous chemicals is avoided, and the comprehensive energy consumption is relatively low.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment, and more particularly to a wastewater treatment system for pretreated fly ash from waste incineration. Background Technology

[0002] Municipal solid waste incineration fly ash (referred to as "fly ash") originates from the fly ash obtained from the flue gas collection system of waste-to-energy incineration plants. It includes fluidized bed fly ash and grate furnace fly ash. The main components of fly ash are CaO, SiO2, Na2O, K2O, Fe2O3, Al2O3, and MgO. Among them, CaO has the highest mass fraction, ranging from 20.4% to 37.9%. The main hazardous substances are heavy metals (Zn, Pb, Cu, Cr, Cd, Ni, and Hg, etc.) and dioxin-like organic compounds. Chlorine has the highest mass fraction in incineration fly ash, which can exceed 25%. Among them, soluble chlorine accounts for 40.6% to 83.9% of the total chlorine.

[0003] Generally, fly ash washing wastewater originates from the washing process during fly ash resource utilization. It is high-salt wastewater, with Cl as its main component. - Na + K + Ca 2+ SO4 2- and Pb 2+ Zn 2+ Cu 2+ Cd 2+ Cr 6+ Heavy metals, including Cl - Na + K + Sodium chloride and potassium chloride can be produced through evaporation crystallization separation technology. To ensure the quality of these products and the stability of the evaporation crystallization equipment, it is necessary to remove COD, SS, and Ca from the fly ash washing wastewater. 2+ SO4 2- and Pb 2+ Zn 2+ Cu 2+ Cd 2+ Cr 6+ Heavy metal elements.

[0004] Therefore, heavy metal chelating agents are used during the washing process to stabilize heavy metals in fly ash, reduce the precipitation of heavy metals, and also reduce the cost of subsequent wastewater treatment processes.

[0005] Currently, the main methods for removing calcium ions from high-salinity wastewater include sodium carbonate removal, carbon dioxide removal, and sodium sulfate removal. Sodium carbonate removal is the most effective, achieving a calcium ion removal rate greater than 99%. Carbon dioxide removal has lower efficiency and needs to be used in conjunction with sodium carbonate removal, resulting in higher treatment costs. Sodium sulfate removal is difficult to completely remove calcium ions from high-salinity wastewater, and it also introduces large amounts of sulfate, severely affecting the quality of sodium chloride and potassium chloride products from the evaporation and crystallization equipment. Without a removal process, sulfate in fly ash washing wastewater will continuously accumulate in the evaporation and crystallization equipment, also affecting the quality of sodium chloride and potassium chloride products.

[0006] Fly ash washing wastewater contains a certain concentration of COD. Currently, COD removal generally employs physical, chemical, and biochemical methods. However, fly ash washing wastewater contains large amounts of chloride ions and heavy metals, making it unsuitable for biochemical removal. Furthermore, biochemical methods have high startup costs and require significant space. Physical methods can only remove particulate organic matter; they are ineffective for small particles or water-soluble organic matter. Therefore, chemical methods are currently the most common approach for COD removal from fly ash washing wastewater.

[0007] Therefore, there is an urgent need in this field for a waste incineration fly ash washing wastewater treatment system to efficiently remove COD and heavy metals, reduce calcium ions in the wastewater washing solution, ensure the quality of subsequent evaporation and crystallization products, and control treatment costs. Utility Model Content

[0008] In order to solve at least one of the technical problems mentioned in the background art, the purpose of this application is to provide a pre-treated waste incineration fly ash washing wastewater treatment system.

[0009] To achieve the above objectives, this application provides the following technical solution.

[0010] The pretreated wastewater treatment system for fly ash washing from waste incineration includes:

[0011] Fly ash pre-dissolving tank is used to mix fly ash with water to form a slurry and to adjust the pH.

[0012] The fly ash washing system is used to treat the slurry output from the fly ash pre-dissolving tank, so that the heavy metals in the slurry are stabilized in the slurry and the metal salts are washed out, finally obtaining the first mud-water mixture.

[0013] The first solid-liquid separation device is used to perform solid-liquid separation on the first mud-water mixture output from the fly ash washing system to obtain the first sludge and washing wastewater.

[0014] The hardness removal system is used to treat the washing wastewater output from the first solid-liquid separation device to remove calcium and magnesium from the washing wastewater in order to obtain a second mud-water mixture.

[0015] The second solid-liquid separation device is used to separate the second mud-water mixture into solid and liquid components to obtain the second sludge and softened water.

[0016] The COD removal system is used to remove COD from the softened water output from the second solid-liquid separation unit to obtain deionized water.

[0017] The pH adjustment system is used to adjust the pH of the dewatering water output from the COD removal system to obtain neutral adjusted water.

[0018] Filtration equipment is used to filter the conditioned water output from the pH adjustment system to obtain filtered water;

[0019] Evaporation crystallization equipment is used to evaporate and concentrate the filtered water output from filtration equipment to obtain sodium chloride and potassium chloride.

[0020] As an optional implementation of this application, it also includes:

[0021] The fly ash temporary storage bin is located upstream of the fly ash pre-dissolving tank and is used to collect and store fly ash.

[0022] The fly ash conveying system is used to transport fly ash from the fly ash temporary storage bin to the pre-dissolving tank.

[0023] As an optional implementation of this application, it also includes:

[0024] The raw water tank is located downstream of the first solid-liquid separation device and upstream of the hardness removal system, and is used to collect and temporarily store the washing wastewater output from the first solid-liquid separation device.

[0025] As an optional implementation of this application, the pumping pipeline between the raw water tank and the hardness removal system is equipped with a self-priming pump.

[0026] As an optional implementation of this application, the pumping pipeline between the fly ash washing system and the first solid-liquid separation device adopts a screw sludge pump and / or a sludge diaphragm pump.

[0027] And / or the pumping pipeline between the hardening system and the second solid-liquid separation device uses a screw sludge pump and / or a sludge diaphragm pump.

[0028] As an optional embodiment of this application, the pumping pipeline between the second solid-liquid separation device and the COD removal system adopts a self-priming pump;

[0029] And / or the pumping pipeline between the COD removal system and the pH adjustment tank uses a self-priming pump;

[0030] And / or the pumping pipeline between the pH adjustment tank and the filtration equipment uses a self-priming pump;

[0031] And / or the pumping pipeline between the filtration equipment and the evaporation crystallization equipment uses a self-priming pump.

[0032] As an optional embodiment of this application, the first solid-liquid separation device is selected from one or more of a plate and frame filter press, a belt filter press, or a horizontal screw centrifuge.

[0033] The second solid-liquid separation device is selected from one or more of a plate and frame filter press, a belt filter press, or a horizontal screw centrifuge.

[0034] As an optional embodiment of this application, the fly ash pre-dissolving tank is equipped with a pulse acid pump for pulse addition of hydrochloric acid to adjust the pH.

[0035] As an optional embodiment of this application, the COD removal system includes an ozone reaction device.

[0036] As an optional embodiment of this application, the fly ash washing system is equipped with a pulse dosing pump for pulse dosing of DTC, sodium dihydrogen phosphate, and sodium sulfide.

[0037] Compared with the prior art, this application has the following advantages:

[0038] Firstly, in this application, the fly ash washing system can treat the slurry output from the fly ash pre-dissolving tank, thereby stabilizing the heavy metals in the slurry, reducing the construction and treatment costs of subsequent wastewater treatment, avoiding the risks posed by hazardous chemicals, and resulting in lower overall energy consumption.

[0039] Secondly, the COD removal system (ozone reaction equipment) used in this application can remove COD to a large extent, which is beneficial to improving the quality of chloride salts.

[0040] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0041] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings. Several embodiments of this application are illustrated in the drawings by way of example and not limitation, in which:

[0042] In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0043] Figure 1 A process flow diagram of this application is shown. Detailed Implementation

[0044] To make the objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0045] This embodiment provides a pretreated waste incineration fly ash washing wastewater treatment system. It is worth noting that the pretreated waste incineration fly ash mainly refers to the pyrolysis fly ash after dioxin removal by heat treatment, hereinafter referred to as fly ash.

[0046] The system provided in this embodiment includes, in sequence according to the process flow, a fly ash temporary storage bin, a fly ash conveying system, a fly ash pre-dissolving tank, a fly ash washing system, a first solid-liquid separation device, a second solid-liquid separation device, a raw water tank, a hardness removal system, a second solid-liquid separation device, a COD removal system, a pH adjustment system, a filtration device, and an evaporation crystallization device. The following is a detailed description of each component.

[0047] A fly ash temporary storage bin is used to collect and store fly ash, which refers to the pyrolysis fly ash after dioxin removal mentioned above. Specifically:

[0048] The fly ash temporary storage silo is located inside a cofferdam. The cofferdam adopts surface anti-seepage measures. The surface anti-seepage material should be compatible with the material or pollutant it comes into contact with. It can be anti-seepage concrete, high-density polyethylene membrane, sodium bentonite waterproof blanket or other materials with equivalent anti-seepage performance. The basic anti-seepage layer is a clay layer with a thickness of at least 1m (permeability coefficient not greater than 10-7cm / s), or an artificial anti-seepage material such as a high-density polyethylene membrane with a thickness of at least 2mm (permeability coefficient not greater than 10-10cm / s), or other materials with equivalent anti-seepage performance.

[0049] The fly ash conveying system is used to convey fly ash from the fly ash temporary storage bin to the pre-dissolving tank. In some embodiments, the fly ash conveying device is a conveying pipe with multiple layers of paired spiral blades inside. The conveying pipe is divided into a feeding section and a mixing section. The feeding section has a waste incineration fly ash inlet and a pyrolysis batching inlet. In the mixing section, two sets of parallel stirring chains are arranged between adjacent layers of spiral blades. The tail end of the conveying pipe has a material outlet.

[0050] The fly ash pre-dissolving tank is used to mix fly ash with water to form a slurry, which is mainly a mud-water mixture. The pH is adjusted. Specifically, the fly ash pre-dissolving tank is equipped with a pulse acid pump for pulse addition of hydrochloric acid to adjust the pH of the slurry.

[0051] The fly ash washing system is mainly used to treat the slurry output from the fly ash pre-dissolving tank, stabilizing heavy metals in the slurry and washing out metal salts, ultimately obtaining the first mud-water mixture; specifically:

[0052] The fly ash washing system includes a washing tank, a dosing tank, and a rinsing tank. The inlet of the washing tank is connected to the slurry outlet of the fly ash pre-dissolving tank via an overflow pipe. During operation, the slurry output from the fly ash pre-dissolving tank enters the washing tank. The dosing tank adds chelating agents and other reagents to the washing tank, causing the slurry in the washing tank to react with the chelating agents, thereby stabilizing or fixing the heavy metals in the fly ash, reducing the precipitation of heavy metals, and simultaneously washing out sodium and potassium metals from the fly ash for resource recovery.

[0053] The added chelating agents include DTC, sodium dihydrogen phosphate, and sodium sulfide. In some embodiments, the dosing tank can be used to administer the drug via a pulse pump.

[0054] This embodiment utilizes a chelating agent to solidify heavy metals in fly ash, reducing the construction and treatment costs of subsequent wastewater treatment, avoiding the risks posed by hazardous chemicals, and resulting in lower overall energy consumption.

[0055] The first solid-liquid separation device is used to separate the first mud-water mixture output from the fly ash washing system to obtain the first sludge and the washing wastewater. The first sludge is mainly the product of fly ash washing, and the washing wastewater is sodium and potassium-containing wastewater. That is, after the first mud-water mixture is separated by the first solid-liquid separation device, filter residue (i.e., the first sludge) and filtrate (i.e., washing wastewater) are obtained.

[0056] The outlet of the first solid-liquid separation device is connected to the fly ash washing system via a pumping pipeline. Preferably, the pumping pipeline between the fly ash washing system and the first solid-liquid separation device is a screw sludge pump or a sludge diaphragm pump, or a combination of both.

[0057] In some embodiments, the first solid-liquid separation device is selected from one or more of the following: a plate and frame filter press, a belt filter press, or a horizontal screw centrifuge. For example, a plate and frame filter press and a belt filter press may be used simultaneously.

[0058] The raw water tank is located downstream of the first solid-liquid separation unit and is mainly used to collect and temporarily store the washing wastewater output from the first solid-liquid separation unit. The raw water tank can be underground, semi-underground, or above ground, and the raw water tank is made of concrete, Q235 or SUS316L. In addition, the volume of the raw water tank is sufficient to store liquid for 15 hours of continuous operation.

[0059] In addition, the pH of the washing wastewater in the raw water tank can be adjusted; the washing wastewater in the raw water tank is then transported to the hardness removal system for hardness removal treatment.

[0060] The hardness removal system is mainly used to remove hardness from the washing wastewater output from the raw water tank, or to soften it. It mainly removes calcium and magnesium from the washing wastewater to obtain a second mud-water mixture.

[0061] The raw water tank and the hardness removal system are connected by a pumping pipeline. Specifically, the pumping pipeline between the raw water tank and the hardness removal system uses a self-priming pump.

[0062] In some embodiments, the hardening system mainly includes a hardening reaction tank, which comprises a dosing unit and a sedimentation unit. The treatment process of fly ash washing wastewater in the hardening reaction tank includes dosing and sedimentation in sequence. The dosing involves adding sodium carbonate decahydrate solution, which removes calcium and magnesium ions by generating calcium carbonate and other precipitates. The sodium carbonate decahydrate reagent is used to remove calcium and magnesium ions from the wastewater, thus softening the fly ash. The softening effect of the wastewater is the same as that of anhydrous sodium carbonate treatment, but the price is lower, resulting in a treatment cost reduction of over 14.78% and lower overall energy consumption.

[0063] The second solid-liquid separation device is mainly used to separate the second sludge-water mixture output from the hardening system to obtain second sludge and softened water. The second sludge is mainly calcium carbonate sludge, etc. Specifically, the hardening reaction tank and the second solid-liquid separation device are connected by a pumping pipeline. Preferably, the pumping pipeline between the hardening reaction tank and the second solid-liquid separation device adopts a screw sludge pump and / or a sludge diaphragm pump.

[0064] In addition, the second solid-liquid separation device is selected from one or more of the following: plate and frame filter press, belt filter press, or horizontal screw centrifuge. For example, a plate and frame filter press and a belt filter press are used simultaneously.

[0065] The COD removal system is used to treat the softened water output from the second solid-liquid separation unit to remove COD, resulting in water with a low COD concentration. Specifically, the COD removal system can employ an ozone reactor, where ozone is generated by an ozone generator and then introduced into the ozone reactor to remove COD. The ozone reactor is connected to the softened water outlet of the second solid-liquid separation unit via a pumping pipeline, for example, a self-priming pump.

[0066] Using ozone reaction equipment to remove large amounts of COD can achieve a maximum COD removal rate of up to 80%, improving the quality of wastewater and facilitating the stable operation of evaporation crystallization and salt separation equipment, thereby improving the quality of chloride salts.

[0067] The pH adjustment system mainly includes a pH adjustment tank, which is primarily used to adjust the pH of the deionized water output from the COD removal system to obtain neutral water. The pH adjustment tank is connected to the COD removal water outlet of the COD removal system via a pumping pipeline, which can be a self-priming pump.

[0068] The filtration equipment is used to filter the conditioned water output from the pH adjustment tank to obtain filtered water. In some embodiments, the filtration equipment adopts a multi-media filter from the prior art. The multi-media filter is connected to the conditioned water outlet of the pH adjustment tank via a pumping pipeline, which is a self-priming pump. Large particulate impurities are separated from the conditioned water output from the pH adjustment tank by the multi-media filter to obtain filtered water.

[0069] Evaporation crystallization equipment is used to evaporate and concentrate the filtered water output from filtration equipment, crystallizing and separating salts to produce sodium chloride and potassium chloride. Specifically, the evaporation crystallization equipment is connected to the filtrate outlet of the filtration equipment via a pumping pipeline, which can be a self-priming pump. Evaporation crystallization equipment has been extensively described and applied in existing technologies, and will not be elaborated upon further here.

[0070] The specific process of using this system to treat fly ash washing wastewater is as follows:

[0071] S1. The pyrolysis fly ash after dioxin removal (hereinafter referred to as fly ash) enters the fly ash pre-dissolving tank. The fly ash pre-dissolving tank is used to mix fly ash and water to make a slurry, and at the same time, acid is added to adjust the pH.

[0072] S2. The slurry from the fly ash pre-dissolving tank enters the fly ash washing system. DTC, sodium dihydrogen phosphate, and sodium sulfide are added as chelating agents to fix the heavy metals in the fly ash. At the same time, sodium and potassium salts in the fly ash are washed out for recycling. After step S2, the first mud-water mixture is finally obtained.

[0073] S3. The first mud-water mixture undergoes solid-liquid separation using a first solid-liquid separation device to obtain first sludge and washing wastewater. The proportions of various metal ions in the obtained washing wastewater are approximately: chloride ion content 8%–15%, sodium ion content 1%–3%, potassium ion content 1%–3%, and calcium ion content 2%–4%. The washing wastewater is temporarily stored in a raw water tank.

[0074] S4. The washing wastewater in the raw water tank is discharged into the hardening reaction tank for hardening treatment to remove calcium and magnesium ions, thereby obtaining the second mud-water mixture. Industrial sodium carbonate decahydrate is mainly used as the softening agent for hardening.

[0075] S5. The second mud-water mixture is separated into solid and liquid by the second solid-liquid separation device to obtain softened water and second sludge, the second sludge being mainly calcium carbonate sludge, etc.; the calcium carbonate sludge can be processed in the fly ash washing system and finally enter the finished fly ash product for use as a raw material in building materials.

[0076] Among them, the calcium ion removal rate in softened water is greater than 99%, and the water content of calcium carbonate sludge is 30% to 35%.

[0077] S6. Softened water enters the ozone reaction equipment to remove COD and obtain deionized water.

[0078] S7. Remove water and enter the pH adjustment tank. Add acid (such as hydrochloric acid) to adjust the pH to neutral to obtain adjusted water.

[0079] S8. Adjust the water flow into the multi-media filter to remove solid impurities and produce filtered water.

[0080] S9. Filtered water is evaporated and crystallized through an evaporation crystallization device to separate sodium and potassium salts for use in the preparation of sodium chloride and potassium chloride products.

[0081] The waste incineration fly ash washing wastewater treatment system in this embodiment can achieve a wastewater softening and removal cost reduction of more than 14.78%. The treated water (i.e. COD removal system effluent) has a lower COD content than fly ash washing wastewater, which is more conducive to the stable operation of the evaporation crystallization equipment.

[0082] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this application can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this application can be achieved, and this is not limited herein.

[0083] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0084] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A system for treating wastewater from the washing of pre-treated waste incineration fly ash, characterized in that The system comprises: a fly ash pre-dissolution tank for mixing fly ash with water to form a slurry and adjusting pH; a fly ash water washing system for processing the slurry output by the fly ash pre-dissolution tank, so that heavy metals in the slurry are stabilized in the slurry and metal salts are washed out, and finally a first mud-water mixture is obtained; a first solid-liquid separation device for performing solid-liquid separation on the first mud-water mixture output by the fly ash water washing system to obtain first sludge and washing wastewater; a hardness removal system for performing hardness removal treatment on the washing wastewater output by the first solid-liquid separation device to remove calcium and magnesium in the washing wastewater, and obtain a second mud-water mixture; a second solid-liquid separation device for performing solid-liquid separation on the second mud-water mixture to obtain second sludge and softened water; a COD removal system for performing COD removal treatment on the softened water output by the second solid-liquid separation device to obtain removal water; a pH adjustment system for adjusting pH of the removal water output by the COD removal system to obtain neutral adjustment water; a filtration device for filtering the adjustment water output by the pH adjustment system to obtain filtered water; and an evaporation crystallization device for evaporating and concentrating the filtered water output by the filtration device to obtain sodium chloride and potassium chloride.

2. The pre-treated MSWI fly ash wastewater treatment system according to claim 1, characterized in that, The system further comprises: a fly ash temporary storage bin arranged upstream of the fly ash pre-dissolution tank and used for collecting and storing fly ash; a fly ash conveying system for conveying fly ash in the fly ash temporary storage bin to the pre-dissolution tank.

3. The pre-treated MSWI fly ash washing wastewater treatment system according to claim 1 or 2, characterized in that, The system further comprises: a raw water pool arranged downstream of the first solid-liquid separation device and upstream of the hardness removal system, and used for collecting and temporarily storing the washing wastewater output by the first solid-liquid separation device.

4. The pre-treated waste incineration fly ash water washing wastewater treatment system according to claim 3, characterized in that, A pumping pipeline between the raw water pool and the hardness removal system adopts a self-priming pump.

5. The fly ash water washing wastewater treatment system of the pretreated garbage incineration fly ash according to claim 1, wherein a pumping pipeline between the fly ash water washing system and the first solid-liquid separation device adopts a screw sludge pump and / or a sludge diaphragm pump; and / or a pumping pipeline between the hardness removal system and the second solid-liquid separation device adopts a screw sludge pump and / or a sludge diaphragm pump.

6. The fly ash water washing wastewater treatment system of the pretreated garbage incineration fly ash according to claim 1, wherein a pumping pipeline between the second solid-liquid separation device and the COD removal system adopts a self-priming pump; and / or a pumping pipeline between the COD removal system and the pH adjustment tank adopts a self-priming pump; and / or a pumping pipeline between the pH adjustment tank and the filtration device adopts a self-priming pump; and / or a pumping pipeline between the filtration device and the evaporation crystallization device adopts a self-priming pump.

7. The fly ash water washing wastewater treatment system of the pretreated garbage incineration fly ash according to claim 1, wherein the first solid-liquid separation device is selected from one or more of a plate-and-frame filter press, a belt filter press, or a horizontal screw centrifuge; the second solid-liquid separation device is selected from one or more of a plate-and-frame filter press, a belt filter press, or a horizontal screw centrifuge.

8. The pre-treated MSWI fly ash wastewater treatment system of claim 1, wherein, The fly ash pre-dissolution tank is provided with a pulse acid pump for pulse addition of hydrochloric acid to adjust pH.

9. The pre-treated MSWI fly ash wastewater treatment system of claim 1, wherein, The COD removal system comprises an ozone reaction device, and / or the filtration device comprises a multi-media filter.

10. The pre-treated MSWI fly ash wastewater treatment system of claim 1, wherein, The fly ash water washing system is provided with a pulse dosing pump for pulse adding DTC, sodium dihydrogen phosphate and sodium sulfide.

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