Purifying and recycling system for fly ash washing evaporation mother liquor
By employing technologies such as ettringite reaction tanks, solid-liquid separation, pH adjustment, and iron-carbon micro-electrolysis, the problem of impurity ion enrichment in fly ash washing evaporation mother liquor was solved, enabling efficient reuse of mother liquor and stable operation of the evaporation system, thereby improving the quality of crystalline salts and reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZHEJIANG JINGLAN ENVIRONMENTAL PROTECTION TECH CO LTD
- Filing Date
- 2025-04-25
- Publication Date
- 2026-04-28
AI Technical Summary
The concentration of impurity ions such as ammonia nitrogen, nitrate, COD and sulfate in fly ash washing evaporation mother liquor increases with the concentration factor. Direct discharge or reuse will affect the operation of the evaporation system and the quality of crystallized salt, and existing technologies have not been able to effectively solve this problem.
The purification and reuse system consists of an ettringite reaction tank, a solid-liquid separation device, a pH adjustment tank, an iron-carbon micro-electrolysis device, and a stripping tower. Through a series of chemical reactions and physical separation steps, sulfates, nitrates, nitrites, ammonia nitrogen, and carbonates are removed from the mother liquor. The pH value is adjusted and the ammonia nitrogen is controlled by reflux in the stripping tower, ensuring that the reuse of the purified mother liquor does not affect the evaporation system.
It effectively removes impurities from the mother liquor, ensures stable operation of the evaporation system, improves the quality of crystallized salt, reduces operating costs, reduces the generation of calcium sludge in the raw water tank, and achieves efficient reuse of the mother liquor.
Smart Images
Figure CN224172619U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of high-salt wastewater treatment technology, specifically relating to a fly ash water washing evaporation mother liquor purification and reuse system. Background Technology
[0002] With the continuous expansion of waste incineration capacity, the amount of fly ash generated is also increasing daily. Fly ash contains a large amount of soluble chloride salts (such as sodium chloride and potassium chloride) and a small amount of heavy metal ions, as well as trace amounts of impurity ions such as ammonia nitrogen, nitrate, COD, and sulfate. If not properly disposed of, it will seriously harm the environment and affect human health. Fly ash washing is an effective treatment method that can remove chloride salts and heavy metals from fly ash.
[0003] During the washing process, heavy metal ions and soluble chlorides dissolve in the water in ionic form. These are then separated from the fly ash through filtration, yielding detoxified fly ash. The filtrate, containing heavy metals and high concentrations of chlorides, undergoes further pretreatment such as weight and hardness removal before being separated and extracted through evaporation and crystallization to obtain high-quality potassium and sodium salts. The condensate produced by the evaporation system can be recycled back into the front-end washing system, achieving resource utilization.
[0004] However, a small amount of mother liquor is generated during the operation of the evaporation system. The concentration of impurity ions such as ammonia nitrogen, nitrate, COD and sulfate in the mother liquor increases with the concentration factor. If it is discharged directly, it will cause serious pollution to the environment. If it is directly transported to the front-end pretreatment system, impurity ions such as ammonia nitrogen, nitrate, COD and sulfate will continue to accumulate. After reaching a certain level, it will affect the operation of the evaporation system and affect the quality of the crystallized salt.
[0005] Therefore, there is an urgent need in this field to develop a fly ash washing evaporation mother liquor purification and reuse system to ensure efficient reuse of the evaporation mother liquor without affecting the operation of the evaporation system and reducing operating costs. Utility Model Content
[0006] Based on the aforementioned shortcomings and deficiencies in the existing technology, one of the objectives of this utility model is to at least solve one or more of the aforementioned problems in the existing technology. In other words, one of the objectives of this utility model is to provide a fly ash water washing evaporation mother liquor purification and reuse system that meets one or more of the aforementioned requirements.
[0007] To achieve the above-mentioned objectives, this utility model adopts the following technical solution:
[0008] A fly ash washing evaporation mother liquor purification and reuse system includes:
[0009] The ettringite reaction vessel is used to remove sulfates from the mother liquor of fly ash washing evaporation to obtain a mud-water mixture;
[0010] Solid-liquid separation device is used to separate the sludge-water mixture output from the ettringite reaction tank to produce sulfate-free mother liquor and ettringite sludge.
[0011] The first pH adjustment tank is used to adjust the pH of the sulfate-removing mother liquor output from the solid-liquid separation device to obtain the pickling mother liquor.
[0012] The iron-carbon micro-electrolysis equipment is used to remove nitrates, nitrites and COD from the pickling mother liquor output from the first pH adjustment tank, to obtain a mother liquor free of nitrates, nitrites and COD.
[0013] The first stripping tower is used to remove carbonates from the denitrate, nitrite and COD mother liquor output from the iron-carbon micro-electrolysis equipment to obtain decarbonate mother liquor.
[0014] The second pH adjustment tank is used to adjust the pH of the decarbonate mother liquor output from the first stripping tower to obtain an alkaline mother liquor.
[0015] The second stripping tower is used to remove ammonia nitrogen from the alkaline mother liquor output from the second pH adjustment tank, resulting in ammonia nitrogen-free mother liquor.
[0016] As a preferred embodiment, the ettringite reaction tank is connected to the calcium hydroxide storage tank, the anhydrous aluminum chloride storage tank and the flocculant storage tank respectively, and the ettringite reaction tank is connected to the evaporation mother liquor tank for temporary storage by a pump pipeline.
[0017] The calcite reaction vessel is equipped with a stirring device.
[0018] As a preferred embodiment, the ettringite reaction vessel is configured as two sets connected in parallel.
[0019] As a preferred embodiment, the outlet of the ammonia nitrogen removal mother liquor of the second stripping tower is equipped with an online ammonia nitrogen detector. When the online ammonia nitrogen detector detects that the ammonia nitrogen in the ammonia nitrogen removal mother liquor is unqualified, the ammonia nitrogen removal mother liquor is returned to the second pH adjustment tank through the return pipeline.
[0020] As a preferred embodiment, the mother liquor for removing ammonia nitrogen is connected to the raw water tank of fly ash washing liquid via a reuse pipeline.
[0021] As a preferred embodiment, the fly ash washing evaporation mother liquor purification and reuse system also includes:
[0022] The heavy metal removal reaction sedimentation tank is used to remove heavy metals from the fly ash washing liquid output from the raw water tank to obtain de-heavy water.
[0023] The hardness removal reaction sedimentation tank is used to remove calcium and magnesium ions from the heavy water output from the heavy weight removal reaction sedimentation tank to obtain softened water.
[0024] Sand filter tanks are used to remove suspended solids from softened water output from hardness removal reaction sedimentation tanks to obtain de-SS water;
[0025] The third pH adjustment tank is used to adjust the pH of the SS-removed water output from the sand filter tank to obtain neutral water.
[0026] The evaporation crystallization system is used to separate and purify sodium and potassium salts in the neutral water output from the third pH adjustment tank through evaporation crystallization, to obtain industrial by-product salts and discharge the evaporation mother liquor;
[0027] The mother liquor storage tank is used to store the mother liquor output from the evaporation crystallization system.
[0028] As a preferred embodiment, the first pH adjustment tank is connected to the hydrochloric acid tank, and the second pH adjustment tank is connected to the alkali tank.
[0029] As a preferred embodiment, the acid mother liquor from the first pH adjustment tank enters the iron-carbon micro-electrolysis device through a pressurization pipeline.
[0030] As a preferred option, the pumping pipeline between the ettringite reaction tank and the solid-liquid separation device is selected from a screw sludge pump, a pneumatic diaphragm pump, or a slurry pump.
[0031] As a preferred option, the solid-liquid separation device is a horizontal screw centrifuge or a plate and frame filter press.
[0032] Compared with the prior art, the advantages of this utility model are:
[0033] (1) This utility model can efficiently remove sulfate, nitrate, nitrite, ammonia nitrogen and carbonate in the evaporation mother liquor, interrupt the enrichment of COD, and ensure that the quality of the evaporation crystallization product will not be affected after the evaporation mother liquor is reused.
[0034] (2) This utility model utilizes iron-carbon micro-electrolysis to remove a large amount of COD from the mother liquor, achieving a maximum COD removal rate of up to 85%, which improves the water quality of the mother liquor, is more conducive to the stable operation of the evaporation crystallization salt separation equipment, and improves the quality of chloride salts.
[0035] (3) This utility model uses the method of adjusting the pH of the mother liquor and stripping tower to remove most of the ammonia nitrogen and carbonate, which greatly reduces the operating cost and has a lower overall energy consumption compared with other methods.
[0036] (4) This utility model uses a stripping tower to remove carbonates and then returns them to the original water tank, which reduces the generation of calcium sludge in the original water tank.
[0037] (5) This utility model selects the mother liquor to be purified and returned to the original water tank, and then transported to the evaporation system after being de-heavy and de-hardened by the pretreatment system. The existing treatment equipment effectively interrupts the enrichment of heavy metals and calcium ions, which saves costs and ensures the quality of the salt. Attached Figure Description
[0038] Figure 1 This is a schematic diagram of the fly ash water washing evaporation mother liquor purification and reuse system according to an embodiment of this utility model. Detailed Implementation
[0039] To more clearly illustrate the embodiments of this utility model, the specific implementation methods of this utility model will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of this utility model. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.
[0040] Example 1:
[0041] like Figure 1 As shown, the fly ash washing evaporation mother liquor purification and reuse system of this embodiment includes a raw water tank 1, a heavy removal reaction sedimentation tank 2, a hard removal reaction sedimentation tank 3, a sand filter tank 4, a pH adjustment tank 5, an evaporation crystallization system 6, an evaporation mother liquor temporary storage tank 7, an ettringite reaction tank 8, a solid-liquid separation device 9, a pH adjustment tank 10, an iron-carbon micro-electrolysis device 11, a stripping tower 12, a pH adjustment tank 13, and a stripping tower 14.
[0042] In this embodiment, the raw water tank 1 is used to store the washing filtrate, i.e., fly ash washing liquid. Specifically, the raw water tank 1 is underground, semi-underground, or above ground, and the raw water tank is a concrete structure, made of Q235 or SUS316L; in addition, the volume of the raw water tank is sufficient to store liquid for 20 hours of continuous operation.
[0043] In addition, the raw water tank 1 is connected to the fly ash washing wastewater source 0 through a pipeline. The washing wastewater enters the raw water tank by gravity flow in order to treat the fly ash wastewater from the waste incineration.
[0044] In this embodiment, the heavy metal removal reaction sedimentation tank 2 is used to remove heavy metals from the washing wastewater output from the raw water tank 1 to obtain de-heavy water. Specifically, the heavy metal removal reaction sedimentation tank 2 includes a dosing unit, a coagulation reaction unit, a flocculation reaction unit, a sedimentation unit, and a clear liquid storage unit. The heavy metal removal reaction sedimentation tank 2 is connected to the raw water tank 1 via a pumping pipeline. The dosing unit is connected to the coagulation unit and the flocculation unit via a pumping pipeline. The dosing pump is a diaphragm metering pump. The coagulation reaction unit, the flocculation reaction unit, the sedimentation unit, and the clear liquid storage unit are all connected by an overflow method. For details, please refer to the prior art, which will not be elaborated here. The treatment process of fly ash washing wastewater in the heavy metal removal reaction sedimentation tank 2 includes chemical dosing, coagulation reaction, flocculation reaction, and sedimentation. Chemical dosing involves adding hydrochloric acid to adjust the pH and remove heavy metals. The flocculant used in the flocculation reaction is anionic or nonionic PAM. The sedimentation tank is either semi-underground or above-ground, constructed of concrete, made of Q235 or SUS316L steel, and its volume must allow for a settling time of at least 20 hours. The heavy metal removal reaction sedimentation tank 2 is connected to both the hydrochloric acid storage tank 21 and the PAM storage tank 22 for easy chemical dosing.
[0045] In this embodiment, the hardness removal reaction sedimentation tank 3 is used to remove calcium and magnesium ions from the de-heavy water to obtain softened water. Specifically, the hardness removal reaction sedimentation tank 3 includes a dosing unit, a coagulation reaction unit, a flocculation reaction unit, a sedimentation unit, and a clear liquid storage unit. The coagulation unit of the hardness removal reaction sedimentation tank is connected to the clear liquid storage unit of the de-heavy water reaction sedimentation tank via a pump pipeline. The dosing unit is connected to the coagulation unit and the flocculation unit via a pump pipeline. The dosing pump is a diaphragm metering pump. The coagulation reaction unit, flocculation reaction unit, sedimentation unit, and clear liquid storage unit are all connected by an overflow method. For details, please refer to the prior art, which will not be elaborated here. The treatment process of the hardness removal reaction sedimentation tank for de-heavy water includes dosing, coagulation reaction, flocculation reaction, and sedimentation in sequence. Among them, the dosing involves adding sodium carbonate and coagulant PAC; the coagulant for the flocculation reaction is anionic PAM or nonionic PAM; the sedimentation tank is semi-underground or above-ground, using concrete structure, Q235 or SUS316L, and the volume needs to meet a settling time of more than 20 hours. Among them, the hard reaction sedimentation tank 3 is connected to the PAC storage tank 31, PAM storage tank 32 and sodium carbonate storage tank 33 respectively, which facilitates the addition of chemicals.
[0046] In this embodiment, sand filter tank 4 is used to remove suspended solids from softened water to obtain water with desaturated (SS) water. The sand filter tank can be made of Q235 steel, fiberglass, or PP. Two sand filter tanks are used in parallel, with one set on standby during operation. Each set is connected in series with 2-3 stages to ensure that the SS in the effluent is less than 1 mg / L.
[0047] In addition, the sand filter tank 4 is connected to the clear liquid storage unit of the hardening reaction sedimentation tank by a pumping pipeline, and each sand filter tank corresponds to one transfer pump.
[0048] In this embodiment, the pH adjusting tank 5 is used to adjust the pH of the SS-removed water to obtain neutral water. The pH adjusting tank 5 includes a dosing unit and a pH adjusting unit; the added agent is hydrochloric acid; the pH adjusting tank 5 can be made of PP, PE, PPH, or fiberglass; the pH adjusting tank 5 is connected to the sand filter tank 4 via a gravity flow pipe, and the dosing unit is connected to the pH adjusting unit via a pumping pipe, with the dosing pump being a diaphragm metering pump. Specifically, the pH adjusting tank 5 is connected to the hydrochloric acid tank 51 for easy dosing.
[0049] The evaporation crystallization system 6 in this embodiment is used to separate salts from neutral water. It includes evaporation crystallization and cooling crystallization. Evaporation crystallization separates sodium salts by heating and evaporating, while cooling crystallization separates potassium salts by cooling. In addition, the outlet of the pH adjustment tank 5 enters the evaporation crystallization system 6 through a booster pump.
[0050] In this embodiment, the evaporation mother liquor temporary storage tank 7 is used to store the evaporation mother liquor output from the evaporation crystallization system 6, and can be selected from FPR, PPH and TA2 tanks; wherein, the evaporation mother liquor is transported to the evaporation mother liquor temporary storage tank 7 through a pump pipeline.
[0051] In this embodiment, the ettringite reaction tank 8 is used to remove sulfate from the mother liquor output from the temporary storage tank of evaporating mother liquor, obtaining a mud-water mixture. Specifically, the ettringite reaction tank includes a dosing unit, a coagulation reaction unit, and a flocculation unit. The treatment process of the evaporating mother liquor by the ettringite reaction tank includes dosing, coagulation reaction, and flocculation reaction in sequence. Among them, the dosing involves adding anhydrous aluminum chloride and calcium hydroxide; the flocculant for the flocculation reaction is anionic PAM or nonionic PAM; the tank body is a PPH structure, and the packing material is quartz sand; the tank is connected to the evaporating mother liquor tank by a pump pipeline. The ettringite reaction tank 8 is connected to the calcium hydroxide storage tank 81, the anhydrous aluminum chloride storage tank 82, and the flocculant storage tank 83, respectively. The ettringite reaction tank 8 is connected to the temporary storage tank of evaporating mother liquor 7 by a pump pipeline. The ettringite reaction tank 8 is equipped with a stirring device and a diaphragm pump for adding aluminum chloride solution and PAM.
[0052] In addition, two sets of ettringite reaction tanks 8 can be connected in parallel, with each set using a batch processing method.
[0053] In this embodiment, the solid-liquid separation device 9 is used to separate the sludge-water mixture output from the ettringite reactor 8 to produce sulfate-free mother liquor and ettringite sludge. The solid-liquid separation device 9 is connected to the outlet of the flocculation zone of the ettringite reactor via a pumping pipeline.
[0054] In this embodiment, the pH adjusting tank 10 is used to adjust the pH of the sulfate-free mother liquor output from the solid-liquid separation device 9. It includes a dosing unit and a pH adjusting unit; the added agent is hydrochloric acid; the pH adjusting tank 10 can be made of PP, PE, PPH, or fiberglass; the pH adjusting tank 10 is connected to the solid-liquid separation device 9 via a pumping pipeline, and the dosing unit is connected to the pH adjusting unit via a pumping pipeline. The dosing pump is a diaphragm metering pump. The pH adjusting tank 10 is connected to the hydrochloric acid tank 101 for easy dosing.
[0055] In this embodiment, the iron-carbon micro-electrolysis device 11 is used to remove nitrates, nitrites, and COD from the pickling mother liquor output from the pH adjustment tank 10, thereby obtaining electrolyzed water. Specifically, the packing material in the iron-carbon micro-electrolysis device 11 is an iron-carbon column, and the iron-carbon micro-electrolysis device 11 is connected to the outlet of the pH adjustment tank 10 via a pumping pipeline.
[0056] In this embodiment, the stripping tower 12 is used to remove nitrates, nitrites, and carbonates from the COD mother liquor output by the iron-carbon micro-electrolysis device 11. The stripping tower 12 adopts a cylindrical tower structure, uses multi-faceted hollow plastic balls as packing material, and employs a centrifugal fan. The stripping tower 12 is connected to the outlet of the iron-carbon micro-electrolysis device 11 via a pump pipeline. Furthermore, the mother liquor enters the stripping tower 12 from the outlet of the iron-carbon micro-electrolysis device 11 via a booster pump.
[0057] In this embodiment, the pH adjusting tank 13 is used to adjust the pH of the decarbonate mother liquor, and includes a dosing unit and a pH adjusting unit; the added agent is an alkaline solution; the pH adjusting tank 13 can be made of PP, PE, PPH, or fiberglass; the pH adjusting tank 13 is connected to the stripping tower 12 via a pumping pipeline, and the dosing unit is connected to the pH adjusting unit via a pumping pipeline, the dosing pump being a diaphragm metering pump. The pH adjusting tank 13 is connected to the alkaline solution tank 131 for easy dosing.
[0058] In this embodiment, the stripping tower 14 is used to remove ammonia nitrogen from the alkaline mother liquor output from the pH adjustment tank 13. The stripping tower 14 adopts a cylindrical tower structure, and the packing material is Raschig rings and polypropylene Pall rings. The stripping tower 14 is connected to the outlet of the pH adjustment tank 13 via a pump pipeline. Additionally, the mother liquor enters the stripping tower 14 from the outlet of the pH adjustment tank 13 via a booster pump.
[0059] In addition, the outlet of the stripping tower 14 is connected to the raw water tank 1 via a pumping pipeline and is equipped with an online ammonia nitrogen detector, which can monitor and control the return of unqualified mother liquor with ammonia nitrogen to the pH adjustment tank 13 for reprocessing.
[0060] All pumping pipelines for the aforementioned pumped mud-water mixture utilize screw sludge pumps, sludge diaphragm pumps, or slurry pumps, while the remaining pumping pipelines employ self-priming pumps; gravity flow can also be used, depending on the actual installation environment. Furthermore, the pipelines are made of Q235, SUS316L, 2205 duplex stainless steel, or titanium for corrosion protection.
[0061] In this embodiment, the solid-liquid separation device is either a plate and frame filter press or a horizontal screw centrifuge, which can be determined according to the actual application scenario.
[0062] The treatment process of the waste incineration fly ash washing and evaporation mother liquor purification and reuse system in this embodiment includes:
[0063] (1) Fly ash washing liquid enters the raw water tank, and the raw water equalization tank is used to store and homogenize fly ash washing wastewater.
[0064] Specifically, in this embodiment, the fly ash washing wastewater (hereinafter referred to as washing filtrate) contains 138,000 mg / L of chloride ions, 29,000 mg / L of sodium ions, 28,000 mg / L of potassium ions, 35,000 mg / L of calcium ions, 200 mg / L of nitrate, 400 mg / L of sulfate, 30 mg / L of nitrite, 500 mg / L of COD, 60 mg / L of ammonia nitrogen, and 150 mg / L of heavy metals (mainly lead).
[0065] (2) The fly ash washing wastewater from the raw water tank enters the heavy metal removal reaction sedimentation tank to remove heavy metals such as lead, zinc, copper, cadmium, and chromium, generating heavy metal removal wastewater and heavy metal sludge. The heavy metal sludge enters the hazardous waste temporary storage warehouse and is packaged in ton bags and transported by forklift. The removal rate of heavy metals such as lead, zinc, copper, cadmium, and chromium in the heavy metal removal water is greater than 90%, and the water content of the heavy metal sludge is 50-60%.
[0066] (3) The heavy wastewater enters the hardening reaction sedimentation tank for the removal of calcium and magnesium ions (i.e., hardening) to obtain softened and calcium carbonate sludge; the calcium carbonate sludge enters the fly ash washing system and finally enters the washed finished ash, which is used as raw material for building materials; among them, the softening agent used for hardening is industrial sodium carbonate, the coagulant is PAC, and the flocculant is PAM; among them, the calcium ion removal rate in the softened water is greater than 99%, and the water content of the calcium carbonate sludge is 30-35%;
[0067] (4) Softened water enters a sand filter tank for SS removal, resulting in SS-free wastewater. The filter tank packing material is quartz sand with a particle size of 0.9–3 mm. The SS removal rate is 90%, and the SS content in the effluent is less than 1 mg / L.
[0068] (5) The SS-free wastewater enters the pH adjustment tank to adjust the pH of the wastewater to between 7 and 8. After being pumped into the evaporation crystallization system by a booster pump, the sodium salt and potassium salt are separated and purified. The remaining evaporation mother liquor flows into the evaporation mother liquor temporary storage tank by gravity.
[0069] (6) The mother liquor tank is used to store and homogenize the mother liquor (hereinafter referred to as mother liquor);
[0070] Specifically, the evaporation mother liquor contains nitrate at a concentration of 1000–1500 mg / L, sulfate at a concentration of 3500–4000 mg / L, nitrite at a concentration of 300–500 mg / L, COD at a concentration of 3000–4000 mg / L, and ammonia nitrogen at a concentration of 300–350 mg / L.
[0071] (7) The mother liquor in the evaporation mother liquor tank enters the ettringite reaction tank to remove the sulfate and produce a mud-water mixture; the ettringite reaction agent is calcium hydroxide and anhydrous aluminum chloride, and the flocculant is macromolecular cationic PAM.
[0072] (8) Solid-liquid separation is performed on the mud-water mixture to produce sulfate-free mother liquor and ettringite sludge; among which, the ettringite sludge enters the fly ash washing system and finally enters the washed finished ash, which is used as a raw material for building materials; the sulfate removal rate in the mother liquor is greater than 98%, and the water content of the ettringite sludge is 30-35%.
[0073] (9) The sulfate mother liquor enters the iron-carbon micro-electrolysis equipment to remove nitrate, nitrite and COD; before the mother liquor enters the iron-carbon micro-electrolysis equipment, the pH of the mother liquor needs to be adjusted to between 3 and 4 in the pH adjustment tank.
[0074] pH adjustment tank 2 uses hydrochloric acid to adjust the pH; the iron-carbon micro-electrolysis equipment has a removal rate of 85% for nitrate and nitrite and a removal rate of 80% for COD.
[0075] (10) The electrolytic mother liquor enters the stripping tower 1 to remove carbonate ions, and obtains decarbonate mother liquor; the carbonate removal rate is 95%.
[0076] (11) The pH of the carbonate removal mother liquor is adjusted to between 10 and 11 by pH adjustment tank 3, and then sent to stripping tower 3 by booster pump to remove ammonia nitrogen, thus obtaining ammonia nitrogen removal mother liquor, which is then sent to the raw water tank by booster pump.
[0077] The pH adjustment tank 3 uses liquid alkali to adjust the pH; the stripping tower 2 operates at a pressure of 2-3 bar; the ammonia nitrogen removal rate is as high as 98%; in addition, the online ammonia nitrogen monitor is set to 100, and mother liquor that does not meet the requirements will be automatically returned to the pH adjustment tank 3 for reprocessing.
[0078] The fly ash washing evaporation mother liquor purification and reuse process in this embodiment can realize the recycling of evaporation mother liquor without affecting the quality of crystallized salt, saving more than 30% of mother liquor treatment costs and conserving water resources.
[0079] Example 2:
[0080] The fly ash water washing evaporation mother liquor purification and reuse system in this embodiment differs from that in Example 1 in the following aspects:
[0081] It eliminates the need for raw water tank, heavy metal removal reaction sedimentation tank, hard metal removal reaction sedimentation tank, sand filter tank, pH adjustment tank, evaporation crystallization system, and evaporation mother liquor temporary storage tank, and can be directly applied to the evaporation mother liquor treatment of the existing fly ash washing system to meet the needs of different applications;
[0082] Other structures can be found in Example 1.
[0083] Example 3:
[0084] The fly ash water washing evaporation mother liquor purification and reuse system in this embodiment differs from that in Example 1 in the following aspects:
[0085] The online ammonia nitrogen detector at the stripping tower outlet is omitted to meet the needs of different applications;
[0086] Other structures can be found in Example 1.
[0087] The above description is only a detailed explanation of the preferred embodiments and principles of this utility model. For those skilled in the art, there may be changes in the specific implementation methods based on the ideas provided by this utility model, and these changes should also be considered within the protection scope of this utility model.
Claims
1. A system for purifying and reusing fly ash washing evaporation mother liquor, characterized in that, include: The ettringite reaction vessel is used to remove sulfates from the mother liquor of fly ash washing evaporation to obtain a mud-water mixture; Solid-liquid separation device is used to separate the sludge-water mixture output from the ettringite reaction tank to produce sulfate-free mother liquor and ettringite sludge. The first pH adjustment tank is used to adjust the pH of the sulfate-removing mother liquor output from the solid-liquid separation device to obtain the pickling mother liquor. The iron-carbon micro-electrolysis equipment is used to remove nitrates, nitrites and COD from the pickling mother liquor output from the first pH adjustment tank, to obtain a mother liquor free of nitrates, nitrites and COD. The first stripping tower is used to remove carbonates from the denitrate, nitrite and COD mother liquor output from the iron-carbon micro-electrolysis equipment to obtain decarbonate mother liquor. The second pH adjustment tank is used to adjust the pH of the decarbonate mother liquor output from the first stripping tower to obtain an alkaline mother liquor. The second stripping tower is used to remove ammonia nitrogen from the alkaline mother liquor output from the second pH adjustment tank, resulting in ammonia nitrogen-free mother liquor.
2. The fly ash water washing evaporation mother liquor purification and reuse system according to claim 1, characterized in that, The ettringite reaction tank is connected to the calcium hydroxide storage tank, the anhydrous aluminum chloride storage tank and the flocculant storage tank respectively. The ettringite reaction tank is connected to the evaporation mother liquor tank that temporarily stores the evaporation mother liquor by a pump pipeline. The calcite reaction vessel is equipped with a stirring device.
3. The fly ash water washing evaporation mother liquor purification and reuse system according to claim 1, characterized in that, The ettringite reaction tank consists of two sets connected in parallel.
4. The fly ash water washing evaporation mother liquor purification and reuse system according to claim 1, characterized in that, The outlet of the mother liquor for ammonia removal in the second stripping tower is equipped with an online ammonia nitrogen detector. When the online ammonia nitrogen detector detects that the ammonia nitrogen in the mother liquor for ammonia removal is not up to standard, the mother liquor for ammonia removal is returned to the second pH adjustment tank through the return pipeline.
5. The fly ash water washing evaporation mother liquor purification and reuse system according to claim 1, characterized in that, The mother liquor for removing ammonia nitrogen is connected to the raw water tank of fly ash washing liquid through a reuse pipeline.
6. The fly ash water washing evaporation mother liquor purification and reuse system according to claim 5, characterized in that, Also includes: The heavy metal removal reaction sedimentation tank is used to remove heavy metals from the fly ash washing liquid output from the raw water tank to obtain de-heavy water. The hardness removal reaction sedimentation tank is used to remove calcium and magnesium ions from the heavy water output from the heavy weight removal reaction sedimentation tank to obtain softened water. Sand filter tanks are used to remove suspended solids from softened water output from hardness removal reaction sedimentation tanks to obtain de-SS water; The third pH adjustment tank is used to adjust the pH of the SS-removed water output from the sand filter tank to obtain neutral water. The evaporation crystallization system is used to separate and purify sodium and potassium salts in the neutral water output from the third pH adjustment tank through evaporation crystallization, to obtain industrial by-product salts and discharge the evaporation mother liquor; The mother liquor storage tank is used to store the mother liquor output from the evaporation crystallization system.
7. The fly ash water washing evaporation mother liquor purification and reuse system according to claim 1, characterized in that, The first pH adjustment tank is connected to the hydrochloric acid tank, and the second pH adjustment tank is connected to the alkali tank.
8. The fly ash water washing evaporation mother liquor purification and reuse system according to claim 1, characterized in that, The acid mother liquor from the first pH adjustment tank enters the iron-carbon micro-electrolysis equipment through a pressurization pipeline.
9. The fly ash washing evaporation mother liquor purification and reuse system according to claim 1, characterized in that, The pumping pipeline between the ettringite reaction tank and the solid-liquid separation device is selected from screw sludge pumps, pneumatic diaphragm pumps, or slurry pumps.
10. The fly ash water washing evaporation mother liquor purification and reuse system according to claim 1, characterized in that, The solid-liquid separation device is either a horizontal screw centrifuge or a plate and frame filter press.