Preparation method of induced seed crystal for removing cobalt-60 in wastewater

A technology for inducing crystallization and crystal seeding, applied in nuclear engineering, radioactive purification, etc., can solve the problems of difficult solid-liquid separation, low sedimentation efficiency, fine particles, etc., to achieve good sedimentation performance and reduce pollution.

Pending Publication Date: 2022-03-01
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Commonly used chemical precipitants mainly include hydroxides, carbonates and sulfides, etc., which can achieve a good removal effect on cobalt-60, but the particles generated by chemical reactions are small, the sedimentation efficiency is low, and solid-liq

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] The concentration of cobalt ion in the mother liquor prepared by dissolving cobalt chloride in tap water is 5.5mg / L, and adding 10mmol / L calcium carbonate as the induced crystal nucleus to the induced crystallization reactor, adding 10L mother liquor and 60mg / L NaOH, in 70s -1 Stir for 30 minutes at a certain strength, settle for 10 minutes, and discharge 4L of supernatant. After 60 cycles of circulation, the remaining turbidity of the supernatant is 2.0 NTU, the average particle size of the induced seed crystal is 16.57 μm, and the hardness removal rate is 80%.

Embodiment 2

[0023] The concentration of cobalt ion in the mother liquor prepared by dissolving cobalt chloride in tap water is 5.2mg / L, and adding 10mmol / L calcium carbonate as the induced crystal nucleus to the induced crystallization reactor, adding 10L mother liquor and 80mg / L NaOH, in 80s -1 Stir for 30 minutes at a certain strength, settle for 10 minutes, and discharge 4L of supernatant. After 60 cycles of circulation, the remaining turbidity of the supernatant is 1.6 NTU, the average particle size of the induced seed crystals is 17.07 μm, and the hardness removal rate is 85%.

Embodiment 3

[0025] The concentration of cobalt ions in the mother liquor prepared by dissolving cobalt chloride in tap water is 5.0 mg / L. Add 10 mmol / L of calcium carbonate as the induced crystal nucleus to the induced crystallization reactor, add 10 L of mother liquor and 120 mg / L of NaOH, and in 90 s -1 Stir for 30 minutes at a certain strength, settle for 10 minutes, and discharge 4L of supernatant. After 60 cycles of circulation, the remaining turbidity of the supernatant is 1.8 NTU, the average particle size of the induced seed crystal is 17.85 μm, and the hardness removal rate is 95%.

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Abstract

The invention discloses a preparation method of an induced seed crystal for removing cobalt-60 in wastewater. And adding cobalt chloride into tap water, and uniformly mixing to obtain mother liquor for preparing the induced seed crystal. The method comprises the following steps: adding an induced crystal nucleus and a mother solution into an induced crystallization reactor, adding NaOH, carrying out an induced crystallization reaction through rapid stirring, generating a calcium carbonate and cobalt hydroxide mixed crystal by taking the induced crystal nucleus as a core, precipitating, and discharging a supernatant which is a first period of induced crystal seed preparation; the mother liquor is supplemented into the induced crystallization reactor, NaOH is added, induced crystallization reaction is carried out through rapid stirring, supernate is discharged after precipitation, and the process is the second period of induced seed crystal preparation; the circulation is performed for not less than 60 periods, the generated induced seed crystal is large in particle size and good in settling performance, and the residual turbidity of supernate is low.

Description

technical field [0001] The invention belongs to the technical field of radioactive waste water treatment, and relates to a method for preparing mixed seed crystals, in particular to a method for preparing induced seed crystals for removing cobalt-60 in waste water. Background technique [0002] 60 Co is a common activated corrosion product in the primary circuit of reactors and spent fuel reprocessing, and it widely exists in radioactive wastewater. 60 Co is a highly toxic nuclide with a half-life of 5.27 years. The gamma rays generated during the decay process release powerful energy, destroying cell tissue and even DNA. Long-term exposure to radiation can also cause cancer, cataracts, etc. Cobalt-60 wastewater Processing is a burning problem. [0003] The chemical precipitation method for cobalt-60 wastewater treatment has simple process, convenient operation and mature technology, and has been widely used in industry. Commonly used chemical precipitants mainly include ...

Claims

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Application Information

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IPC IPC(8): G21F9/10
CPCG21F9/10
Inventor 张光辉钟瑶瑶郭俊男
Owner TIANJIN UNIV
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