Treatment method of chlorine-containing wastewater in rare earth smelting technical process

A process and wastewater technology, applied in water/sewage treatment, chemical instruments and methods, water/sludge/sewage treatment, etc., can solve the problems of severe equipment corrosion, high energy consumption, and no market for chlorides, etc. To achieve the effect of ensuring zero emissions

Pending Publication Date: 2019-04-05
CENT SOUTH UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Evaporation and crystallization of metal chloride solution not only consumes a lot of energy, but also causes severe corrosion of equipment by chloride ions
Freezing and crystallization can reduce the corrosion of equipment, but the obtained chlorides usually cannot be sold with crystal water, and most of the chlorides are deliquescent, such as calcium chloride, magnesium chloride, etc., which are difficult to preserve

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Take Cl - Concentration of 78.9g / L rare earth chloride calcium soap after liquid 5m 3 Add anhydrous sodium sulfate according to 1 times the theoretical amount of calcium chloride converted into sodium chloride, stir at 85°C for 1.5h, add alkali to adjust the pH to 3.0, make the calcium in it precipitate in the form of gypsum, filter to obtain NaCl solution and Gypsum filter cake, gypsum purity>99.5%, then feed HCl gas into the obtained NaCl solution, so that the sodium chloride in it is supersaturated and precipitated, and filtered to obtain NaCl-containing hydrochloric acid solution and NaCl crystals with a purity of 99.38%, the hydrochloric acid solution The mass percentage concentration is 29.7%, and wherein NaCl content is 3.3g / L; Gained hydrochloric acid solution containing sodium chloride returns and is used as the leaching liquid of rare earth mineral, and the straight recovery rate of process chlorine is 97.45%, and the recovery rate of chlorine> 99.3%.

Embodiment 2

[0029] Take Cl - Concentration of 81.9g / L rare earth chloride calcium soap after liquid 5m 3 , add anhydrous sodium sulfate according to 1 times the theoretical amount of sodium chloride converted from calcium chloride, stir at 85°C for 1.5h, make the calcium in it precipitate in the form of gypsum, filter to obtain NaCl solution and gypsum filter cake, the purity of gypsum is > 99.5%, and then add 10mol / L hydrochloric acid to the resulting NaCl solution to adjust the solution H + Concentration reaches 6mol / L, and the hydrochloric acid solution of NaCl and the NaCl crystal that filtration gets NaCl and purity are 99.67%, the concentration of described hydrochloric acid solution is 6mol / L, and wherein NaCl content is 30.6g / L; Gained hydrochloric acid solution containing sodium chloride returns It is used as the back-extraction liquid for the extraction of the loaded organic phase in the production of rare earth carbonate. The direct recovery rate of chlorine in the process is ...

Embodiment 3

[0031] Add 120 g of anhydrous sodium carbonate to 300 mL of the concentrated rare earth carbonate precipitated solution with a NaCl concentration of 296 g / L, stir at 65 ° C for 2 h, and filter to obtain NaCl-containing Na 2 CO 3 solution and NaCl crystals with a purity of 99.43%, the NaCl 2 CO 3 The content of NaCl in the solution is 129.5g / L; Gained Na 2 CO 3 The solution is returned and continues to be used as a precipitation solution for rare earth carbonate. The direct recovery rate of chlorine in the process is 56.25%, and the recovery rate of chlorine is >99.4%.

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Abstract

The invention discloses a treatment method of chlorine-containing wastewater in a rare earth smelting technical process. The method comprises the following steps of firstly converting the chlorine-containing wastewater generated in the rare earth smelting process into a sodium chloride-containing solution through adding lime and sodium sulfate, then, adding hydrochloric acid used in the rare earthsmelting technical process or introducing a HCl gas into the sodium chloride-containing solution, by utilizing a common ion effect generated by a chlorine ion, impelling sodium chloride in an obtained mixture to precipitate and separate out, or adding sodium carbonate or / and sodium hydrogen carbonate, by utilizing the common ion effect generated by a sodium ion, impelling the sodium chloride in an another obtained mixture to precipitate and separate out, and filtering to obtain a sodium chloride crystal. Without evaporation concentration, chlorine in the chlorine-containing wastewater can beseparated. The method has the advantages of being clean, environment-friendly, economical and efficient, and the like, and is suitable for the industrial application of the treatment of the chlorine-containing wastewater in the rare earth smelting technical process.

Description

technical field [0001] The invention belongs to the field of chemical metallurgy, and in particular relates to a method for treating chlorine-containing wastewater in a rare earth smelting process. Background technique [0002] Due to the good solubility of rare earth chlorides and the abundant sources of hydrochloric acid, which are cheap, hydrochloric acid is often used as the leaching solution of rare earth minerals and the stripping solution of rare earth solvent extraction, resulting in a large amount of chlorine-containing wastewater generated in the rare earth smelting process. The main steps of producing chlorine-containing wastewater in the rare earth smelting process are saponification and precipitation processes. The alkali used in the saponification process is selected from sodium hydroxide, magnesium hydroxide, lime and ammonia water. The waste water produced by the sodium soap process contains sodium chloride, the waste water produced by the magnesium soap pro...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F1/58C02F101/12
CPCC02F1/58C02F2101/12
Inventor 王学文孟钰麒王懿何汉兵王明玉杜艳苹
Owner CENT SOUTH UNIV
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