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CN-121974521-A - Circulation treatment method of high-fluorine mother liquor

CN121974521ACN 121974521 ACN121974521 ACN 121974521ACN-121974521-A

Abstract

The invention discloses a cyclic treatment method of high-fluorine mother liquor, and relates to the technical field of electroplating wastewater treatment. The method comprises the steps of mixing MVR mother liquor and raw water containing chromium according to the volume ratio of 1:250-500, then adding agents such as aluminum sulfate, PAC and PAM for physical and chemical treatment to remove COD, fluoride and hardness, then utilizing resin containing aluminum functional groups for deep fluorine removal to control the fluoride content of effluent to be lower than 7mg/L, and finally conveying the effluent to an MVR evaporator for evaporation circulation. Through a specific mixing proportion and a double defluorination process, the problems of crystallization and hardening of the high-fluorine mother solution and the problem of corrosion of the MVR evaporator are effectively solved. The data show that the process can reduce fluoride to below 0.02mg/L, and the system has stable conductivity and no scaling phenomenon. The method reduces the treatment amount of the mother liquor outside the hazardous waste commission, realizes the reduction of hazardous waste, obviously reduces the operation cost and prolongs the service life of equipment.

Inventors

  • ZHANG PENG
  • ZHANG GUOTIAN
  • LI XULU
  • HE JINGWEN
  • WANG YUANZHE
  • LUO HAO
  • HUANG YUNSHAN
  • TAO GUANGXU

Assignees

  • 四川金茂源环保科技有限公司

Dates

Publication Date
20260505
Application Date
20260212

Claims (9)

  1. 1. The recycling treatment method of the high-fluorine mother liquor is characterized by comprising the following steps of: S1, introducing MVR mother liquor into a chromium-containing wastewater regulating tank, and mixing and diluting with chromium-containing raw water according to the volume ratio of 1:250-500; s2, a physical and chemical treatment step, namely adding a reagent into the mixed wastewater, and removing COD, fluoride and hardness in the wastewater through physical and chemical reaction, wherein the reagent comprises sodium metabisulfite, aluminum sulfate, PAC and PAM; S3, resin adsorption, namely introducing the wastewater subjected to physical and chemical treatment into an ion exchange resin column to perform deep defluorination, and controlling the concentration of fluoride in the effluent to be lower than 7mg/L; And S4, an evaporation circulation step, namely conveying effluent after resin adsorption to an MVR evaporator as a feed for evaporation treatment, condensing and recycling generated secondary steam, and enabling the concentrated mother solution to enter the mixing dilution step again for circulation treatment.
  2. 2. The method for recycling high-fluorine mother liquor according to claim 1, wherein in the step of S1 mixing and diluting, the mixing volume ratio of MVR mother liquor to raw water containing chromium is 1:250.
  3. 3. The recycling method of high-fluorine mother liquor according to claim 1, wherein after mixing in the step of S1 mixing and diluting, the conductivity of the regulating tank is maintained at 3100-4380 mu S/cm.
  4. 4. The recycling method of the high-fluorine mother liquor according to claim 1, wherein in the S2 physical and chemical treatment step, aluminum sulfate and aluminum ions in PAC are reacted with fluoride ions to generate aluminum fluoride precipitates and aluminum hydroxide colloid, fluoride and particulate matters are removed through coprecipitation, polymer chain adsorption bridging of PAM is used for accelerating flocculating settling, a biochemical system is used for degrading COD in wastewater, and softening resin is used for removing hardness and fluoride in wastewater.
  5. 5. The method for recycling high-fluorine mother liquor according to claim 1, wherein in the step of S3 resin adsorption, the ion exchange resin is an aluminum-containing functional group resin, after resin adsorption is saturated, the resin is regenerated by using a crystalline aluminum chloride solution with the concentration of 8%, and 1.6kg of crystalline aluminum chloride is dissolved in 60L of water to prepare a regenerant, wherein the amount of processable mother liquor in a single regeneration period is 145L.
  6. 6. The method for recycling a high-fluorine mother liquor according to claim 5, wherein the concentration of fluoride in effluent can be reduced to less than 0.02mg/L before the next adsorption of the regenerated resin.
  7. 7. The method according to claim 1, wherein in the evaporation circulation step, the fluoride concentration in the feed liquid to the MVR evaporator is controlled to be not more than 200mg/L.
  8. 8. The method of claim 1, wherein the evaporating and circulating step further comprises a control logic for controlling the MVR evaporator to continuously operate for 13 days in a single time when the fluoride concentration of the feed is 3mg/L, shortening the number of days in a single time according to a negative correlation when the fluoride concentration of the feed is increased, and discharging a part of the mother liquor to circulate before the fluoride concentration reaches 200 mg/L.
  9. 9. The method for recycling high-fluorine mother liquor according to claim 1, wherein the concentration of fluoride is 173mg/L to 243mg/L before the MVR mother liquor enters the resin adsorption step, and crystallization or hardening of the resin does not occur in the concentration range.

Description

Circulation treatment method of high-fluorine mother liquor Technical Field The invention relates to the technical field of electroplating wastewater treatment, in particular to a recycling treatment method of high-fluorine mother liquor. Background With the increasing strictness of industrial wastewater treatment standards, the treatment of high-fluorine and high-salt wastewater becomes a difficult point. Mechanical Vapor Recompression (MVR) technology is widely applied to the field of wastewater evaporation due to energy conservation and high efficiency, but in actual operation, mother liquor generated by an MVR system often enriches high-concentration fluoride, COD (chemical oxygen demand) and hardness, and is currently used as hazardous waste, and entrusted with high treatment cost of qualification units. Currently, the treatment of MVR mother liquor is usually done by off-site disposal, which results in extremely high operating costs. Although attempts exist in the prior art to reflux mother liquor to a front-end biochemical or physicochemical system for cyclic treatment, the following technical bottlenecks are faced: the high-fluorine mother liquor directly enters the MVR evaporator, so that the operation time is short, crystallization and hardening are easy, equipment is easy to damage, and the cost is high. The concentration of fluoride in MVR mother liquor is extremely high, if direct reflux or improper treatment is carried out, scaling and corrosion in an evaporation system are extremely easy to cause, and the single continuous operation time of equipment is obviously shortened. The lack of clear data support of the mother liquor reflux on impact load (such as conductivity fluctuation and COD impact) of the chromium-containing wastewater treatment system leads to the problem that the prior system balance is worried about being destroyed in industrial application, so that the closed loop circulation is not easily attempted. At present, the mother liquor in the prior art is directly and completely entrusted to a third party as hazardous waste disposal, which is not beneficial to environmental protection and has higher cost. Therefore, there is a need for a MVR mother liquor recycling method that can solve the crystallization and hardening problems in the recycling process of high-fluorine mother liquor, and can precisely control the feed concentration to ensure the long-period stable operation of the system, thereby reducing the MVR mother liquor from being used as a hazardous waste commission. Disclosure of Invention In order to solve the problems, the invention provides a recycling treatment method of high-fluorine mother liquor, Specifically, the method comprises the following steps: s1, introducing MVR mother liquor into a chromium-containing wastewater regulating tank, and mixing and diluting with chromium-containing raw water according to the volume ratio of 1:250-500. And S2, a physical and chemical treatment step, namely adding a reagent into the mixed wastewater, and removing COD, fluoride and hardness in the wastewater through physical and chemical reaction, wherein the reagent comprises sodium metabisulfite, aluminum sulfate, PAC and PAM. And S3, resin adsorption, namely introducing the wastewater subjected to physical and chemical treatment into an ion exchange resin column for deep defluorination, and controlling the concentration of fluoride in the effluent to be lower than 7mg/L. And S4, an evaporation circulation step, namely conveying effluent after resin adsorption to an MVR evaporator as a feed for evaporation treatment, condensing and recycling generated secondary steam, and enabling the concentrated mother solution to enter the mixing dilution step again for circulation treatment. Specifically, in the step of S1 mixing and diluting, the mixing volume ratio of MVR mother liquor to raw water containing chromium is 1:250. Specifically, after the S1 mixing and diluting step is mixed, the conductivity of the regulating tank is maintained at 3100-4380 mu S/cm. Specifically, in the step of S2 physical and chemical treatment, aluminum sulfate and aluminum ions in PAC are reacted with fluoride ions to generate aluminum fluoride precipitates and aluminum hydroxide colloid, fluoride and particulate matters are removed through coprecipitation, polymer chain adsorption bridging action of PAM is used for accelerating flocculating constituent sedimentation, a biochemical system is used for degrading COD in wastewater, and softening resin is used for removing hardness and fluoride in wastewater. Specifically, in the step of S3 resin adsorption, the ion exchange resin is an aluminum-containing functional group resin, after the resin adsorption is saturated, the resin is regenerated by using a crystalline aluminum chloride solution with the concentration of 8%, and 1.6kg of crystalline aluminum chloride is dissolved in 60L of water to prepare a regenerant, wherein the mother liquor amount in a si