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CN-121990710-A - Harmless purification and reutilization method for low-temperature evaporation concentration of waste acid

CN121990710ACN 121990710 ACN121990710 ACN 121990710ACN-121990710-A

Abstract

The invention discloses a low-temperature evaporation concentration harmless purification recycling method of waste acid, which comprises the following steps of S1, pre-removing impurities of industrial waste acid, S1-1, pre-filtering industrial waste acid, S1-2, crystallizing filtered waste acid, S1-3, performing solid-liquid separation through low-temperature centrifugal separation after crystallizing, S2, performing low-temperature evaporation concentration, ultrasonic collaborative vacuum pulsation evaporation treatment, S3, performing gradient membrane separation and performing low-temperature recrystallization, wherein an ultrasonic collaborative vacuum pulsation evaporation mechanism is designed, and a core problem of low-temperature evaporation mass transfer efficiency and easy scaling is solved through ultrasonic rupture of membranes and vacuum pulsation update interface.

Inventors

  • ZHANG JUN
  • LIU LINLI
  • LV YANG
  • CAO JIE
  • WANG YI
  • ZHANG HOUHU

Assignees

  • 生态环境部南京环境科学研究所

Dates

Publication Date
20260508
Application Date
20260123

Claims (10)

  1. 1. The harmless purification and recycling method for low-temperature evaporation concentration of waste acid is characterized by comprising the following steps of: s1, pre-impurity removal treatment of industrial waste acid: S1-1, pre-filtering industrial waste acid through a modified polytetrafluoroethylene composite membrane; s1-2, the filtered waste acid enters a low-temperature crystallization tank, and a composite crystallization inducer is added into the tank for crystallization treatment; S1-3, after crystallization treatment, carrying out solid-liquid separation through low-temperature centrifugal separation at the temperature of 5 ℃ to obtain the industrial waste acid after impurity removal; S2, low-temperature evaporation concentration and ultrasonic collaborative vacuum pulsation evaporation treatment: Conveying the industrial waste acid subjected to the pre-impurity removal treatment into a low-temperature evaporation kettle, and performing low-temperature evaporation treatment at 35-55 ℃ in a vacuum environment, so that the industrial waste acid is concentrated to 70-80% by mass fraction to obtain concentrated acid liquor; S3, gradient membrane separation and low-temperature recrystallization treatment: S3-1, gradient membrane separation treatment, namely filtering and concentrating concentrated acid liquor by two-stage ceramic ultrafiltration membranes with different retention performances; Forming primarily purified acid liquor by the concentrated acid liquor passing through the ceramic ultrafiltration membrane; S3-2, carrying out low-temperature recrystallization treatment, namely conveying the primarily purified acid liquor into a low-temperature recrystallization tank, cooling the primarily purified acid liquor to-5~0 ℃ at a cooling rate of 1-2 ℃ per minute, and standing at a constant temperature for 4-6 hours to enable acid components in the primarily purified acid liquor to form crystals; finally, filtering and separating the crystals from the mother liquor at the low temperature of-2~0 ℃ to obtain high-purity acid crystals; s4, acid liquor regeneration and tailing innocent treatment: And (3) sending the high-purity acid crystals into a dissolving tank, adding the condensed water obtained in the step S2 for dissolving, and adjusting the acid liquor concentration to the standard required by production to obtain regenerated acid liquor which can be recycled in the original production process.
  2. 2. The method for innocuous purification and reuse of waste acid by low temperature evaporation concentration according to claim 1, wherein in step S1-1, the pore diameter of the modified polytetrafluoroethylene composite membrane is controlled to be 0.1-0.5 μm, the filtration pressure is controlled to be 0.2-0.3 mpa, and the filtration temperature is 25-30 ℃.
  3. 3. The method for innocuous purification and reuse of low-temperature evaporation concentration of waste acid according to claim 1, wherein in the crystallization treatment process of step S1-2, the temperature is controlled to be 0-5 ℃, the stirring speed is 50-80 r/min, and the constant temperature crystallization is carried out for 2-3 hours; The compound crystallization inducer is prepared by compounding trisodium citrate and sodium pyrophosphate according to a mass ratio of 2:1; The mass fraction of the composite crystallization inducer is 0.5-1.0%.
  4. 4. The method for innocuous purification and reuse of low-temperature evaporation concentration of waste acid according to claim 1, wherein in step S1-3, in low-temperature centrifugal separation, the rotation speed is controlled to be 8000-10000 r/min, and centrifugal treatment is carried out for 20-30 min; the heavy metal content in the industrial waste acid after the pre-impurity removal treatment is less than or equal to 5mg/L.
  5. 5. The method for innocuous purification and reuse of low-temperature evaporation concentration of waste acid according to claim 1, wherein in step S2, an ultrasonic transducer with the power density of 100-150W/L is installed in a low-temperature evaporation kettle, and ultrasonic vibration energy is continuously applied to industrial waste acid; The vacuum degree in the low-temperature evaporation kettle is periodically pulsed and regulated within a period of 60s, and the vacuum degree in the low-temperature evaporation kettle is periodically regulated within a range of-0.08 to 0.09 Mpa.
  6. 6. The method for low-temperature evaporation concentration harmless purification and reuse of waste acid according to claim 1, characterized in that in step S2, steam generated by evaporation is conveyed to a condensing tank through a pipeline, the condensing tank liquefies the steam at 5-10 ℃ to obtain condensed water, the conductivity of the condensed water is less than or equal to 50 mu S/cm, and the condensed water can be directly reused for production water or further treated and then discharged.
  7. 7. The method for innocuous purification and reuse of low-temperature evaporation concentration of waste acid according to claim 1, wherein in step S3-1, the primary membrane is an Al 2 O 3 -TiO 2 composite ceramic membrane with a molecular weight cut-off of 500-1000 Da, and macromolecular organic impurities and microsuspensions remained in the concentrated acid solution are removed; the secondary membrane is a modified SiO 2 ceramic membrane with a molecular weight cut-off of 100-300 Da, and can selectively cut off trace metal ions and anion impurities in the acid liquor.
  8. 8. The method for innocuous purification and reuse of waste acid by low temperature evaporation concentration according to claim 7, wherein in step S3-1, in the gradient membrane separation, the pressure of the membrane separation is controlled to be 0.4-0.6 mpa, and the temperature is controlled to be 30-40 ℃.
  9. 9. The method for innocuous purification and reuse of waste acid by low-temperature evaporation concentration is characterized in that in the step S4, crystalline complex generated by pre-impurity removal treatment is mixed with mother liquor generated by low-temperature recrystallization and then is treated as a tailing, 10-15% of modified zeolite powder and 5-8% of calcium hydroxide powder by mass are added into the tailing, and stirring is continuously carried out for 2-3 hours at the temperature of 25-35 ℃ to enable heavy metal ions in the tailing to form hydroxide or silicate coordination compound, fluoride ions form calcium fluoride precipitate, and the solidified tailing can be obtained by filter pressing treatment after the reaction is completed; And regulating the filtrate produced by filter pressing to be neutral, and discharging.
  10. 10. The method for innocuous purification and reuse of waste acid by low temperature evaporation concentration according to claim 9, wherein in step S4, the modified zeolite powder is zeolite powder activated by 3wt% hydrochloric acid; the pressure is 1.0-1.2 mpa during the filter pressing treatment, so that the moisture content of the obtained solidified tailings is less than or equal to 20%.

Description

Harmless purification and reutilization method for low-temperature evaporation concentration of waste acid Technical Field The invention relates to the technical field of industrial waste acid treatment, in particular to a low-temperature evaporation concentration harmless purification and reutilization method of waste acid. Background The industrial waste acid refers to acid waste liquid which is generated in the industrial production process and contains inorganic acid or organic acid with higher concentration, and is commonly used in the industries of chemical industry, metallurgy, electroplating, pharmacy, metal processing and the like. The main components of the water-soluble organic compound can comprise sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, hydrofluoric acid and the like, and generally contain pollutants such as heavy metal ions, organic matters, grease and the like, and the water-soluble organic compound has strong corrosiveness, toxicity and environmental hazard. The industrial waste acid treatment is required to follow the principles of reduction, recycling and harmless treatment, however, the treatment method in the prior art has the defects in the aspects of recovery rate and treatment effect, and needs to be further improved and optimized. Disclosure of Invention The invention aims to provide a harmless purification and recycling method for low-temperature evaporation concentration of waste acid, and an ultrasonic-vacuum-pulsation-evaporation-combined mechanism is designed to enable the low-temperature concentration of the waste acid to be more efficient. In order to achieve the above purpose, the present invention provides the following technical solutions: a low-temperature evaporation concentration harmless purification and reutilization method of waste acid comprises the following steps: s1, pre-impurity removal treatment of industrial waste acid: S1-1, pre-filtering industrial waste acid through a modified polytetrafluoroethylene composite membrane; s1-2, the filtered waste acid enters a low-temperature crystallization tank, and a composite crystallization inducer is added into the tank for crystallization treatment; S1-3, after crystallization treatment, carrying out solid-liquid separation through low-temperature centrifugal separation at the temperature of 5 ℃ to obtain the industrial waste acid after impurity removal; S2, low-temperature evaporation concentration and ultrasonic collaborative vacuum pulsation evaporation treatment: Conveying the industrial waste acid subjected to the pre-impurity removal treatment into a low-temperature evaporation kettle, and performing low-temperature evaporation treatment at 35-55 ℃ in a vacuum environment, so that the industrial waste acid is concentrated to 70-80% by mass fraction to obtain concentrated acid liquor; S3, gradient membrane separation and low-temperature recrystallization treatment: S3-1, gradient membrane separation treatment, namely filtering and concentrating concentrated acid liquor by two-stage ceramic ultrafiltration membranes with different retention performances; Forming primarily purified acid liquor by the concentrated acid liquor passing through the ceramic ultrafiltration membrane; S3-2, carrying out low-temperature recrystallization treatment, namely conveying the primarily purified acid liquor into a low-temperature recrystallization tank, cooling the primarily purified acid liquor to-5~0 ℃ at a cooling rate of 1-2 ℃ per minute, and standing at a constant temperature for 4-6 hours to enable acid components in the primarily purified acid liquor to form crystals; finally, filtering and separating the crystals from the mother liquor at the low temperature of-2~0 ℃ to obtain high-purity acid crystals; s4, acid liquor regeneration and tailing innocent treatment: And (3) sending the high-purity acid crystals into a dissolving tank, adding the condensed water obtained in the step S2 for dissolving, and adjusting the acid liquor concentration to the standard required by production to obtain regenerated acid liquor which can be recycled in the original production process. Preferably, in the step S1-1, the pore diameter of the modified polytetrafluoroethylene composite membrane is controlled to be 0.1-0.5 mu m, the filtration pressure is controlled to be 0.2-0.3 Mpa, and the filtration temperature is 25-30 ℃. The treatment process can accurately intercept suspended particles and colloid impurities in the waste acid, so that the removal rate of the suspended particles and the colloid impurities is more than or equal to 98 percent. Preferably, in the crystallization treatment process of the step S1-2, the temperature is controlled to be 0-5 ℃, the stirring speed is 50-80 r/min, and the crystallization is carried out for 2-3 hours at constant temperature; the compound crystallization inducer is prepared by compounding trisodium citrate and sodium pyrophosphate according to a mass ratio of 2:1; The mass fract