阅读说明：本技术 一种资源化处置氟化体系稀土熔盐电解废气的方法 (Method for recycling treatment of rare earth molten salt electrolysis waste gas of fluorination system ) 是由 王瑞祥 杨裕东 钟晓聪 曾婕 周杰 王艳阳 袁远亮 刘茶香 于 2019-10-09 设计创作，主要内容包括：本发明公开了一种资源化处置氟化体系稀土熔盐电解废气的方法,述方法包括：步骤1,采用以固体稀土氯化物为原料,制备饱和稀土氯化物溶液；步骤2,将氟化体系熔盐电解废气通入其中与溶液中的稀土氯化物反应,得到稀土氟化物沉淀及氯化氢气体；步骤3,分别对其进行收集处理,所得稀土氟化物返回电解工序,所得氯化氢经过处理后返回萃取工序。本发明具有以下有益效果：(1)本发明中的氟化体系稀土熔盐电解废气处理工艺处理效果好,并且具有很好的处理效率；(2)本发明中的氟化体系稀土熔盐电解废气处理工艺可以产生循环利用产品,提高经济效益。(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.)

1. A method for recycling treatment of rare earth molten salt electrolysis waste gas of a fluoridation system 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;

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.

2. The method for recycling the waste gas generated by electrolyzing the rare earth molten salt in the fluoridation system according to claim 1, wherein the prepared rare earth chloride solution is a saturated solution.

3. The method for recycling the rare earth molten salt electrolysis waste gas of the fluoridation system according to claim 1 or 2, wherein the rare earth chloride solution is placed in a gas-liquid reactor, and the feeding flow rate is 40-65 m under the conditions that the temperature is 25-60 ℃ and the rotation speed is 100-400 r/min³H molten salt electrolysis off-gas.

4. 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.

5. 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%.

6. The method for recycling the rare earth molten salt electrolysis waste gas of the fluoridation system according to claim 1, wherein the hydrogen chloride gas discharged with the gas flow is condensed by a water circulation condenser, and after concentration, a high-concentration refined hydrogen chloride solution is obtained, and the concentration of the solution is more than 37%; returning to the extraction process in the rare earth molten salt electrolysis as a washing agent.

7. The method for recycling the rare earth molten salt electrolysis waste gas of the fluoridation system according to claim 1, wherein the obtained rare earth fluoride is filtered, washed and dried in vacuum to obtain high-purity rare earth fluoride solid with the purity of more than 99.97%; returning to the rare earth molten salt electrolysis process for electrolysis.

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 fluorination system.

Background

At present, in the industrial production of rare earth metals in China, particularly in southern 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 fluoride system molten salt electrolysis waste gas with 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 chlorine ions and 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 with the purity of more than 99.97 percent can be obtained, the rare earth fluoride solid is returned to the rare earth molten salt electrolysis procedure for electrolysis, and the defluorination rate of gas is more than 99.9 percent.

The invention has the following beneficial effects: (1) the treatment process for the rare earth molten salt electrolysis waste gas in 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 taking 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 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 rate 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 off-gas is stopped, the gas-liquid reactor 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