CN110846691B - Method for recycling treatment of rare earth molten salt electrolysis waste gas of fluorination system - Google Patents
Method for recycling treatment of rare earth molten salt electrolysis waste gas of fluorination system Download PDFInfo
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- CN110846691B CN110846691B CN201910951987.8A CN201910951987A CN110846691B CN 110846691 B CN110846691 B CN 110846691B CN 201910951987 A CN201910951987 A CN 201910951987A CN 110846691 B CN110846691 B CN 110846691B
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/006—Wet processes
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
- C25C3/34—Electrolytic production, recovery or refining of metals by electrolysis of melts of metals not provided for in groups C25C3/02 - C25C3/32
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Abstract
The invention discloses a method for recycling fluoride system rare earth molten salt electrolysis waste gas, which comprises the following steps: step 1, preparing a saturated rare earth chloride solution by using solid rare earth chloride as a raw material; step 2, introducing the fluoride system molten salt electrolysis waste gas into the solution to react with the rare earth chloride in the solution to obtain rare earth fluoride precipitate and hydrogen chloride gas; and 3, respectively collecting and treating the rare earth fluoride, returning the obtained rare earth fluoride to an electrolysis process, and returning the obtained hydrogen chloride to an extraction process after treatment. The invention has the following beneficial effects: (1) the treatment process for the rare earth molten salt electrolysis waste gas of the fluoridation system has good treatment effect and good treatment efficiency; (2) the treatment process of the rare earth molten salt electrolysis waste gas of the fluoridation system can produce recycled products and improve economic benefits.
Description
Technical Field
The invention belongs to the technical field of waste gas treatment, and particularly relates to a method for treating rare earth molten salt electrolysis waste gas of a fluoridation system.
Background
At present, in the industrial production of rare earth metals in China, particularly in south ionic rare earth, a fluoridation system molten salt electrolysis process is mostly adopted, a certain amount of fluorine-containing waste gas is often generated in the production process, but because the content of fluorine in the waste gas generated in the production process is not high, a set of equipment with good fluorine removal effect needs to be built, the investment cost is large, and the simple and applicable method for treating the fluorine-containing waste gas is not mature enough. Therefore, most production enterprises directly discharge the waste gas generated in the production process without treatment, thereby causing environmental pollution.
A method for treating the waste gas generated by the molten salt electrolysis of the fluoridation system, which has simple process and environmental protection, is urgently needed.
Disclosure of Invention
The invention aims to provide a simple-process, green and environment-friendly method for treating fluoride system rare earth molten salt electrolysis waste gas, and the method can effectively solve the problem of resource treatment of fluoride system molten salt electrolysis waste gas in industrial production at the present stage.
In order to achieve the purpose, the technical scheme of the invention is as follows:
the invention discloses a technical scheme of a method for recycling fluoride system rare earth molten salt electrolysis waste gas, which comprises the following steps: (1) preparing a saturated rare earth chloride solution by taking solid rare earth chloride as a raw material; (2) introducing the fluoride system molten salt electrolysis waste gas into the solution to react with the rare earth chloride in the solution to obtain rare earth fluoride precipitate and hydrogen chloride gas; (3) respectively collecting and treating the rare earth fluoride and the hydrogen chloride to prepare the required high-purity rare earth fluoride solid and refined hydrogen chloride solution, wherein the rare earth fluoride returns to the electrolysis process, and the hydrogen chloride returns to the extraction process.
In the step (1), the solid rare earth chloride is used as a raw material, and the specific steps for preparing the saturated rare earth chloride solution are as follows:
in a constant temperature bath, industrial grade rare earth chloride with the purity of 99.99 percent is taken, the rare earth chloride which is slightly excessive is stirred and dissolved, after standing, supernatant fluid is taken, and the concentration of the obtained saturated rare earth chloride solution is not lower than 200 g/L.
In the step (2), the molten salt electrolysis waste gas is introduced into the solution to react with the rare earth chloride in the solution, and the specific steps of obtaining rare earth fluoride precipitate and hydrogen chloride gas are as follows:
placing the saturated rare earth chloride solution in a stirring bubbling kettle type reactor to ensure sufficient quantity, and introducing the saturated rare earth chloride solution at a flow speed of 40-65 m under the conditions that the temperature is 25-60 ℃ and the rotating speed is 100-400 r/min3H molten salt electrolysis off-gas.
The specific principle is as follows: the fused salt electrolysis waste gas is introduced into the saturated rare earth chloride solution and reacts with the rare earth chloride in the solution,
ReCl3+3HF→ReF3↓+3HCl
the fluorine ions have stronger binding capacity than the chlorine ions and the rare earth cations, and can convert the fluorine ions in the molten salt electrolysis waste gas into rare earth fluoride precipitates. While hydrogen chloride is discharged with the gas stream.
The steps (3) are respectively collected to prepare the required high-purity rare earth fluoride solid and refined hydrogen chloride solution, the rare earth fluoride returns to the electrolysis process, and the hydrogen chloride returns to the extraction process, and the concrete steps are as follows:
the hydrogen chloride gas discharged with the gas flow is condensed and concentrated by a water circulation condenser to obtain a high-purity hydrogen chloride solution, the concentration of the high-purity hydrogen chloride solution is more than 37 percent, and the high-purity hydrogen chloride solution is returned to the extraction process in the rare earth molten salt electrolysis to be used as a detergent. After the reactor completely finishes working, the obtained rare earth fluoride is filtered, washed and dried in vacuum, high-purity rare earth fluoride solid can be obtained, the purity of the rare earth fluoride solid is more than 99.97%, the rare earth fluoride solid returns to the rare earth molten salt electrolysis procedure for electrolysis, and the defluorination rate of the gas is more than 99.9%.
The invention has the following beneficial effects: (1) the treatment process for the rare earth molten salt electrolysis waste gas of the fluoridation system has good treatment effect and good treatment efficiency; (2) the treatment process of the rare earth molten salt electrolysis waste gas of the fluoridation system can produce recycled products and improve economic benefits.
Detailed Description
The present invention will be further described below, and it should be noted that the following examples are provided to illustrate the detailed embodiments and specific procedures based on the technical solution, but the scope of the present invention is not limited to the examples.
The invention relates to a method for recycling fluoride system rare earth molten salt electrolysis waste gas, which comprises the following steps:
step 1, preparing a saturated rare earth chloride solution by using solid rare earth chloride as a raw material;
step 2, introducing the fluoride system molten salt electrolysis waste gas into the solution to react with the rare earth chloride in the solution to obtain rare earth fluoride precipitate and hydrogen chloride gas;
and 3, respectively collecting and treating the rare earth fluoride, returning the obtained rare earth fluoride to an electrolysis process, and returning the obtained hydrogen chloride to an extraction process after treatment.
The prepared rare earth chloride solution is a saturated solution.
The rare earth chloride solution is placed in a gas-liquid reactor, and the flow velocity of the rare earth chloride solution is 40-65 m under the conditions that the temperature is 25-60 ℃ and the rotating speed is 100-400 r/min3H molten salt electrolysis off-gas.
It should be noted that, after the introduction of the molten salt electrolysis waste gas is stopped, the gas-liquid reactor still continues to operate for 1 hour.
It should be noted that the fluorine removal rate for the gas is more than 99.9%.
The hydrogen chloride gas discharged along with the gas flow is condensed by a water circulation condenser and concentrated to obtain a high-concentration refined hydrogen chloride solution, wherein the concentration of the high-concentration refined hydrogen chloride solution is more than 37%; returning to the extraction process in the rare earth molten salt electrolysis as a washing agent.
The rare earth fluoride obtained is filtered, washed and dried in vacuum to obtain high-purity rare earth fluoride solid, and the purity of the high-purity rare earth fluoride solid is more than 99.97%; returning to electrolysis in rare earth molten salt electrolysis process
The first embodiment is as follows:
setting the temperature to room temperature in a constant temperature tank, taking industrial grade neodymium chloride with the purity of 99.99 percent, stirring and dissolving the industrial grade neodymium chloride with slightly excessive neodymium chloride, standing, and taking supernatant fluid to obtain saturated neodymium chloride solution. Placing saturated neodymium chloride solution in a stirring bubbling tank type reactor, and introducing at a flow rate of 55m at a temperature of 50 ℃ and a rotation speed of 300r/min3H molten salt electrolysis waste gas (fluorine content of the fluorine-containing waste gas is 45% by a measuring method). The neodymium fluoride precipitate and the hydrogen chloride gas are treated separately.
Filtering and vacuum drying the obtained neodymium fluoride to obtain neodymium fluoride solid with the purity of 99.98 percent, and returning the neodymium fluoride solid to the electrolysis process of the neodymium fluoride molten salt for continuous electrolysis; condensing the hydrogen chloride gas discharged with the gas flow through a water circulation condenser, concentrating to obtain refined hydrogen chloride solution with the concentration of 38%, and returning the refined hydrogen chloride solution to the extraction process of molten salt electrolysis to be used as a detergent. The fluorine content in the discharged gas is measured to be 0.003 percent and the fluorine removal rate is 99.993 percent, which reaches the national emission standard.
Example two:
setting the temperature to room temperature in a constant temperature tank, taking industrial-grade cerium chloride with the purity of 99.99 percent, stirring and dissolving the industrial-grade cerium chloride with a little excess of cerium chloride, standing the solution, and taking supernatant fluid to obtain saturated cerium chloride solution. Placing saturated cerium chloride solution in a stirred bubbling tank reactor, and introducing at a flow rate of 60m at a temperature of 50 ℃ and a rotation speed of 300r/min3H molten salt electrolysis waste gas (fluorine content of the fluorine-containing waste gas is 45% by a measuring method). The obtained cerium fluoride precipitate and hydrogen chloride gas were treated separately.
Filtering and vacuum drying the obtained cerium fluoride to obtain cerium fluoride solid with the purity of 99.99 percent, and returning the cerium fluoride solid to the electrolysis process of the cerium fluoride molten salt for continuous electrolysis; the hydrogen chloride gas discharged with the gas flow is condensed and concentrated by a water circulation condenser to obtain refined hydrogen chloride solution with the concentration of 39 percent, and the refined hydrogen chloride solution is returned to the extraction procedure of molten salt electrolysis to be used as a detergent. The fluorine content in the discharged gas is measured to be 0.005 percent and the fluorine removal rate is 99.989 percent, which reach the national emission standard.
Example three:
in a constant temperature tank, setting the temperature to room temperature, taking industrial grade lanthanum chloride with the purity of 99.99 percent, stirring and dissolving the industrial grade lanthanum chloride with a little excess lanthanum chloride, standing, and taking supernatant fluid to obtain saturated lanthanum chloride solution. Placing saturated lanthanum chloride solution in a stirring bubbling kettle type reactor, and introducing at a flow rate of 60m under the conditions of a temperature of 45 ℃ and a rotation speed of 400r/min3H molten salt electrolysis waste gas (fluorine content of the fluorine-containing waste gas is 45% by a measuring method). And respectively treating the obtained lanthanum fluoride precipitate and the hydrogen chloride gas.
Filtering and vacuum drying the obtained lanthanum fluoride to obtain lanthanum fluoride solid with the purity of 99.99 percent, and returning the lanthanum fluoride solid to the electrolysis process of the lanthanum fluoride molten salt for continuous electrolysis; the hydrogen chloride gas discharged with the gas flow is condensed and concentrated by a water circulation condenser to obtain refined hydrogen chloride solution with the concentration of 39 percent, and the refined hydrogen chloride solution is returned to the extraction procedure of molten salt electrolysis to be used as a detergent. The fluorine content in the discharged gas is measured, and the fluorine content in the discharged gas is 0 percent, the fluorine removal rate is 100 percent, and the national emission standard is achieved.
Various corresponding changes and modifications can be made by those skilled in the art based on the above technical solutions and concepts, and all such changes and modifications should be included in the protection scope of the present invention.
Claims (3)
1. A method for recycling a fluoride system rare earth molten salt electrolysis waste gas is characterized by comprising the following steps:
step 1, preparing a saturated rare earth chloride solution by using solid rare earth chloride as a raw material;
step 2, introducing the fluoride system molten salt electrolysis waste gas into the solution to react with the rare earth chloride in the solution to obtain rare earth fluoride precipitate and hydrogen chloride gas;
step 3, respectively collecting and treating the rare earth fluoride, returning the obtained rare earth fluoride to an electrolysis process, and returning the obtained hydrogen chloride to an extraction process after treatment;
wherein the rare earth chloride solution is placed in a gas-liquid reactor, and the flow velocity is 40-65 m under the conditions that the temperature is 25-60 ℃ and the rotating speed is 100-400 r/min3H molten salt electrolysis waste gas; condensing the hydrogen chloride gas discharged with the gas flow through a water circulation condenser, and concentrating to obtain a high-concentration refined hydrogen chloride solution, wherein the concentration of the high-concentration refined hydrogen chloride solution is more than 37%; returning to the extraction process in the rare earth molten salt electrolysis as a washing agent; filtering, washing and vacuum drying the obtained rare earth fluoride to obtain high-purity rare earth fluoride solid with the purity of more than 99.97 percent; returning to the rare earth molten salt electrolysis process for electrolysis.
2. The method for recycling the rare earth molten salt electrolysis waste gas of the fluorinated system according to claim 1, wherein the gas-liquid reactor is still operated for 1 hour after the introduction of the molten salt electrolysis waste gas is stopped.
3. The method for recycling the waste gas generated in the electrolysis of rare earth molten salt in the fluoridation system according to claim 1, wherein the defluorination rate of the gas is more than 99.9%.
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Citations (6)
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| CN102796872A (en) * | 2011-05-27 | 2012-11-28 | 深圳市格林美高新技术股份有限公司 | Method for recycling rare earths from cathode-ray tube fluorescent powder |
| CN103143235A (en) * | 2013-02-28 | 2013-06-12 | 包头稀土研究院 | Method for treating tail gas during production process for rare-earth metals and alloys |
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| CN108654347A (en) * | 2018-04-17 | 2018-10-16 | 江苏金石稀土有限公司 | A kind of method that fluoride system electrolysis rare earth waste gas recovery utilizes |
| CN109487089A (en) * | 2019-01-07 | 2019-03-19 | 江西理工大学 | A kind of method of rare earth fluoride molten-salt electrolysis Slag treatment |
| CN209173735U (en) * | 2018-11-22 | 2019-07-30 | 西安西骏新材料有限公司 | A kind of Wan An training rare earth-iron-boron electrolytic cell and waste gas recovering device |
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2019
- 2019-10-09 CN CN201910951987.8A patent/CN110846691B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102796872A (en) * | 2011-05-27 | 2012-11-28 | 深圳市格林美高新技术股份有限公司 | Method for recycling rare earths from cathode-ray tube fluorescent powder |
| CN103143235A (en) * | 2013-02-28 | 2013-06-12 | 包头稀土研究院 | Method for treating tail gas during production process for rare-earth metals and alloys |
| CN105603459A (en) * | 2016-02-03 | 2016-05-25 | 中南大学 | Rare-earth electrolysis fume cleaning system and method |
| CN108654347A (en) * | 2018-04-17 | 2018-10-16 | 江苏金石稀土有限公司 | A kind of method that fluoride system electrolysis rare earth waste gas recovery utilizes |
| CN209173735U (en) * | 2018-11-22 | 2019-07-30 | 西安西骏新材料有限公司 | A kind of Wan An training rare earth-iron-boron electrolytic cell and waste gas recovering device |
| CN109487089A (en) * | 2019-01-07 | 2019-03-19 | 江西理工大学 | A kind of method of rare earth fluoride molten-salt electrolysis Slag treatment |
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Effective date of registration: 20230110 Address after: 314500 Science and Technology Innovation Park, Gaoqiao Street, Tongxiang City, Jiaxing City, Zhejiang Province Patentee after: TONGXIANG SIYUAN ENVIRONMENTAL PROTECTION TECHNOLOGY Co.,Ltd. Address before: 86 No. 341000 Jiangxi city of Ganzhou province Zhanggong District Hongqi Avenue Patentee before: Jiangxi University of Science and Technology |