阅读说明：本技术 一种利用螯合剂浸出废弃荧光粉中稀土元素的方法 (Method for leaching rare earth elements in waste fluorescent powder by using chelating agent ) 是由 于明明 肖俊杰 原伟泉 梅光军 于 2020-12-04 设计创作，主要内容包括：本发明涉及稀土二次资源回收及再生利用技术领域,具体来说是一种利用微波-螯合剂浸出废弃荧光粉中稀土元素的方法,依次采用微波-螯合剂浸出、离子交换树脂吸附、草酸沉淀方法、高温煅烧方法得到混合稀土氧化物,针对目前废弃荧光粉中稀土元素化学浸出工艺存在的酸碱浓度高、用量大,易造成二次污染和设备腐蚀等技术缺陷和技术问题,从资源有效利用、减少环境污染的角度出发,并利用微波辐射引起的高温和高压条件获得的反应促进效果,以及螯合剂对稀土元素的优异亲和力,采用螯合剂作为浸出剂浸出废弃荧光粉中的稀土元素。(The invention relates to the technical field of rare earth secondary resource recovery and recycling, in particular to a method for leaching rare earth elements in waste fluorescent powder by using a microwave-chelating agent, which sequentially adopts a microwave-chelating agent leaching method, an ion exchange resin adsorption method, an oxalic acid precipitation method and a high-temperature calcination method to obtain mixed rare earth oxide.)

1. A method for leaching rare earth elements in waste fluorescent powder by using a chelating agent is characterized by comprising the following steps:

(1) mixing the waste fluorescent powder and the chelating agent solution, placing the mixture in a microwave reactor, adjusting the pH of a reaction system to 3-5 by adopting a buffer solution, reacting for 1-6h under the conditions of microwave power of 400-1200W and temperature of 30-100 ℃, and filtering to obtain rare earth leachate and leaching slag;

wherein the concentration of the chelating agent is 0.05-5mmol/L, and the solid-to-liquid ratio of the waste fluorescent powder to the chelating agent is 1 g: 1-1000 mL;

(2) putting the rare earth leachate obtained in the step (1) into an ion exchange column, and performing rare earth ion adsorption of ion exchange resin to obtain saturated resin;

(3) leaching the rare earth ions in the saturated resin in the step (2) to obtain rare earth-rich leacheate;

(4) precipitating the rare earth-rich leacheate obtained in the step (3) to obtain a rare earth salt precipitate;

(5) and (4) roasting the rare earth salt precipitate in the step (4) at the temperature of 800-1000 ℃ for 1-2h to obtain the mixed rare earth oxide.

2. The method for leaching rare earth elements from waste fluorescent powder by using a chelating agent as claimed in claim 1, wherein the waste fluorescent powder in the step (1) is waste phosphor for a waste lamp, phosphor for a waste cathode ray tube display, LED phosphor for a waste lamp or waste material containing rare earth which is unqualified and generated in the production process of the phosphor.

3. The method for leaching rare earth elements in waste fluorescent powder by using the chelating agent as claimed in claim 1, wherein the chelating agent in the step (1) is one or more of ethylenediamine tetraacetic acid, nitrilotriacetic acid, iminodisuccinic acid, N- (2-hydroxyethyl) iminodiacetic acid and diethylenetriamine pentaacetic acid.

4. The method for leaching rare earth elements in waste fluorescent powder by using a chelating agent as claimed in claim 1, wherein the ion exchange resin in the step (2) is a strong-acid styrene cation exchange resin or a chelating styrene amino carboxyl ion exchange resin or a weak-acid acrylic cation exchange resin.

5. The method for leaching rare earth elements in waste fluorescent powder by using the chelating agent as claimed in claim 1, wherein the leaching agent used in the leaching operation in the step (3) is saturated ammonium sulfate or saturated ammonium chloride.

6. The method for leaching rare earth elements in waste fluorescent powder by using the chelating agent as claimed in claim 1, wherein the method for precipitating the rare earth-rich leacheate in the step (4) is as follows: adding the rare earth-rich leacheate into 50-100g/L of precipitation-causing liquid, preserving heat for 1-2h at 80-90 ℃, and filtering;

wherein the precipitation solution is selected from oxalic acid, ammonium carbonate solution or ammonium bicarbonate solution.

7. The method as claimed in claim 1, wherein the buffer solution of step (1) is selected from one or more of 2-morpholine ethanesulfonic acid biological buffer, 4-hydroxyethylpiperazine ethanesulfonic acid biological buffer, sodium N-tris (hydroxymethyl) methyl-3-aminopropanesulfonate biological buffer, and 3- (cyclohexylamine) -2-hydroxy-1-propanesulfonic acid biological buffer.

Technical Field

The invention relates to the technical field of rare earth secondary resource recovery and recycling, in particular to a method for leaching rare earth elements in waste fluorescent powder by using a chelating agent.

Background

The rare earth element is widely applied due to unique properties of magnetism, light, electricity and the like, is an indispensable element for manufacturing materials and equipment such as precision guidance weapons, permanent magnets, night vision goggles and the like, is an important strategic resource, and causes the continuous increase of the demand of the rare earth resource, and the analysis of Alonso, Long and the like considers that the annual increment rate of the demand of the rare earth resource is between 3.7% and 8.6%, the consumption of the rare earth resource is 16 ten thousand tons in 2016, the consumption of the rare earth resource is expected to increase to 20-24 ten thousand tons in 2020, while the total annual rare earth resource yield of the whole world is about 11 ten thousand tons, and the increasing demand of the rare earth resource cannot be met. The reserves of heavy ion rare earth in Jiangxi province are 230 ten thousand tons, the reserve of long-term view is 940 ten thousand tons, the reserve is the first in China and is the famous big rare earth province, but according to the current rare earth resource consumption, the guarantee supply years of the heavy rare earth resources represented by the ionic rare earth in Jiangxi province are only about 20 years, and the stable supply of the rare earth resources such as neodymium, terbium, dysprosium and the like in the future mainly comes from the recycling of the secondary rare earth resources.

The rare earth fluorescent powder is widely applied to the fields of fluorescent lamps, cathode ray tubes, LEDs and the like as an important luminescent material, and is prepared by mixing red powder, green powder and blue powder according to a certain proportion. The rare earth elements Y and Eu mainly exist in red powder, and the red powder belongs to rare earth oxide and is easy to leach. The blue powder and the green powder belong to stable spinel structures, and the stable structures are difficult to damage by conventional acid leaching. At present, chemical ore dressing methods such as acid leaching method and roasting method are generally adopted to preferentially leach rare earth elements in red powder. As for rare earth elements in green powder and blue powder, dry mechanical activation is carried out on the waste fluorescent powder on a planetary ball mill by people such as Tan pure silver, the leaching rate of the rare earth elements Ce and Tb in the waste fluorescent powder can be increased to over 90 percent, and the leaching time can be greatly shortened. Digamber GP and the like mix the green powder and the blue powder with sodium carbonate according to a certain proportion, and roast the mixture at a high temperature of 1000 ℃ to realize the recovery of rare earth elements in the green powder and the blue powder. However, hydrochloric acid, nitric acid, sulfuric acid or sodium hydroxide used in the above methods are likely to cause secondary environmental pollution and corrosion of leaching equipment.

The invention provides a process for leaching rare earth elements in waste fluorescent powder by chelating agent induction-microwave radiation reinforcement for replacing a conventional acid-base leaching agent for the first time, so as to reduce environmental pollution and equipment corrosion and realize green and efficient leaching of the rare earth elements in the waste fluorescent powder.

Disclosure of Invention

Aiming at the technical defects of high acid and alkali consumption, equipment corrosion, environmental pollution and the like in the leaching process in the prior art, the invention provides a method for leaching rare earth elements in waste fluorescent powder by using a chelating agent, which utilizes the reaction promotion effect obtained under the conditions of high temperature and high pressure caused by microwave radiation, recovers the rare earth elements from the waste fluorescent powder through the excellent affinity of the chelating agent to metals, realizes the efficient and green leaching of the rare earth elements in the waste fluorescent powder, and provides theoretical reference for the recovery and cyclic utilization of the rare earth elements in the waste rare earth fluorescent powder.

In order to solve the technical problems, the invention adopts the following technical scheme:

a method for leaching rare earth elements in waste fluorescent powder by using a chelating agent comprises the following steps:

(1) mixing the waste fluorescent powder and the chelating agent solution, placing the mixture in a microwave reactor, adjusting the pH of a reaction system to 3-5 by adopting a buffer solution, reacting for 1-6h under the conditions of microwave power of 400-1200W and temperature of 30-100 ℃, and filtering to obtain rare earth leachate and leaching slag;

wherein the concentration of the chelating agent is 0.05-5mmol/L, and the solid-to-liquid ratio of the waste fluorescent powder to the chelating agent is 1 g: 1-1000 mL;

(2) putting the rare earth leachate obtained in the step (1) into an ion exchange column, and performing rare earth ion adsorption of ion exchange resin to obtain saturated resin;

(3) leaching the rare earth ions in the saturated resin in the step (2) to obtain rare earth-rich leacheate;

(4) precipitating the rare earth-rich leacheate obtained in the step (3) to obtain a rare earth salt precipitate;

(5) and (4) roasting the rare earth salt precipitate in the step (4) at the temperature of 800-1000 ℃ for 1-2h to obtain the mixed rare earth oxide.

Preferably, the waste fluorescent powder in the step (1) is waste three-primary-color fluorescent powder for lamps, waste cathode-ray tube display fluorescent powder, waste LED fluorescent powder for lamps or waste containing rare earth which is unqualified and generated in the production process of the fluorescent powder.

Preferably, the chelating agent in the step (1) is one or more of ethylenediamine tetraacetic acid, nitrilotriacetic acid, iminodisuccinic acid, N- (2-hydroxyethyl) iminodiacetic acid and diethylenetriamine pentaacetic acid.

Preferably, the ion exchange resin in the step (2) is a strongly acidic styrene cation exchange resin, a chelating styrene aminocarboxyl ion exchange resin, or a weakly acidic acrylic cation exchange resin.

Preferably, the eluting solution used in the eluting operation in step (3) is saturated ammonium sulfate or saturated ammonium chloride.

Preferably, the method for precipitating the rare earth-rich leacheate in the step (4) comprises the following steps: adding the rare earth-rich leacheate into 50-100g/L of precipitation-causing liquid, preserving heat for 1-2h at 80-90 ℃, and filtering;

wherein the precipitation solution is selected from oxalic acid, ammonium carbonate solution or ammonium bicarbonate solution.

Preferably, the buffer solution in step (1) is selected from one or more of 2-morpholine ethanesulfonic acid biological buffer, 4-hydroxyethyl piperazine ethanesulfonic acid biological buffer, N-tris (hydroxymethyl) methyl-3-aminopropanesulfonic acid sodium biological buffer and 3- (cyclohexylamine) -2-hydroxy-1-propanesulfonic acid biological buffer.

Compared with the prior art, the invention has the beneficial effects that:

(1) the method for leaching rare earth elements in the waste fluorescent powder by using the microwave-chelating agent is green and environment-friendly, and the equipment corrosion is small; aiming at the technical defects and technical problems that the leaching process in the prior art needs large amounts of acid and alkali, equipment corrosion, environmental pollution and the like are easily caused, the invention provides a reaction promoting effect obtained under the conditions of high temperature and high pressure caused by microwave radiation, and the rare earth elements are recovered from the waste fluorescent powder through the excellent affinity of a chelating agent to metals, so that the high-efficiency and green leaching of the rare earth elements in the waste fluorescent powder is realized.

(2) The chelating agent used in the invention has excellent extraction performance on rare metals, can be recycled, and has high utilization rate.

(3) According to the invention, a microwave-chelating agent leaching method, an ion exchange resin adsorption method and an oxalic acid precipitation method are sequentially adopted, so that a large amount of non-rare earth impurities can be removed, rare earth elements are selected, and the rare earth oxide with high purity is obtained after calcination; compared with the leaching only by adopting microwave and the leaching only by adopting a chelating agent, the technical effect is obviously superior to the addition of the two results by adopting a single mode, and the unexpected technical effect is achieved.

Drawings

Fig. 1 is a technical route adopted in the technical solutions of embodiments 1 to 3 of the present invention.

Detailed Description

The following description of the preferred embodiments and the accompanying drawings are incorporated in and constitute a part of this specification.

Example 1

A method for leaching rare earth elements in waste fluorescent powder by using a chelating agent comprises the following steps:

(1) mixing the waste fluorescent powder with an aminotriacetic acid solution with the concentration of 0.05mmol/L, and placing the mixture into a microwave reactor, wherein the solid-to-liquid ratio of the waste fluorescent powder to the aminotriacetic acid solution is 1 g: 1mL, adjusting the pH value of a reaction system to 3 by using a buffer solution, reacting for 1h under the conditions of microwave power of 400W and temperature of 100 ℃, and filtering to obtain rare earth leachate and leaching residues;

the waste fluorescent powder is waste three-primary-color fluorescent powder for lamps, waste cathode-ray tube display fluorescent powder, waste LED fluorescent powder for lamps or unqualified waste containing rare earth generated in the production process of the fluorescent powder;

(2) putting the rare earth leachate obtained in the step (1) into an ion exchange column, and performing rare earth ion adsorption by using chelating styrene amino carboxyl ion exchange resin to obtain saturated resin;

(3) leaching the rare earth ions in the saturated resin in the step (2), wherein the leaching agent is a saturated ammonium sulfate solution to obtain a rare earth-rich leaching solution;

(4) precipitating the rare earth-rich eluent obtained in the step (3), adding the rare earth-rich eluent into 50g/L ammonium carbonate solution, preserving the heat for 2 hours at 80 ℃, and filtering to obtain rare earth salt precipitate;

(5) and (4) roasting the rare earth salt precipitate obtained in the step (4) at 800 ℃ for 2h to obtain the mixed rare earth oxide.

Example 2

A method for leaching rare earth elements in waste fluorescent powder by using a chelating agent comprises the following steps:

(1) mixing the waste fluorescent powder with an ethylene diamine tetraacetic acid solution with the concentration of 2mmol/L, and placing the mixture in a microwave reactor, wherein the solid-to-liquid ratio of the waste fluorescent powder to the ethylene diamine tetraacetic acid solution is 1 g: 200mL, adjusting the pH value of the reaction system to 5 by adopting a buffer solution, reacting for 4 hours under the conditions of the microwave power of 1000W and the temperature of 50 ℃, and filtering to obtain rare earth leachate and leaching residues;

the waste fluorescent powder is waste three-primary-color fluorescent powder for lamps, waste cathode-ray tube display fluorescent powder, waste LED fluorescent powder for lamps or unqualified waste containing rare earth generated in the production process of the fluorescent powder;

(2) putting the rare earth leachate obtained in the step (1) into an ion exchange column, and adsorbing rare earth ions by adopting strong-acid cation exchange resin to obtain saturated resin;

(3) leaching the rare earth ions in the saturated resin in the step (2), wherein the leaching agent is a saturated ammonium sulfate solution to obtain a rare earth-rich leaching solution;

(4) precipitating the rare earth-rich leacheate obtained in the step (3), adding the rare earth-rich leacheate into 80g/L oxalic acid solution, preserving heat for 1.5 hours at 85 ℃, and filtering to obtain rare earth salt precipitate;

(5) and (4) roasting the rare earth salt precipitate obtained in the step (4) at 900 ℃ for 1.5h to obtain the mixed rare earth oxide.

Example 3

A method for leaching rare earth elements in waste fluorescent powder by using a chelating agent comprises the following steps:

(1) mixing waste fluorescent powder with a mixed solution of iminodisuccinic acid and N- (2-hydroxyethyl) iminodiacetic acid, placing the mixed solution in a microwave reactor, wherein the concentration of the mixed solution of iminodisuccinic acid and N- (2-hydroxyethyl) iminodiacetic acid is 5mmol/L, and the solid-to-liquid ratio of the waste fluorescent powder to the mixed solution of iminodisuccinic acid and N- (2-hydroxyethyl) iminodiacetic acid is 1 g: 1000mL, adjusting the pH value of the reaction system to 4 by adopting a buffer solution, reacting for 6 hours under the conditions of microwave power of 1200W and temperature of 30 ℃, and filtering to obtain rare earth leachate and leaching residues;

the waste fluorescent powder is waste three-primary-color fluorescent powder for lamps, waste cathode-ray tube display fluorescent powder, waste LED fluorescent powder for lamps or unqualified waste containing rare earth generated in the production process of the fluorescent powder;

(2) putting the rare earth leachate obtained in the step (1) into an ion exchange column, and adsorbing rare earth ions by using weak-acid acrylic cation exchange resin to obtain saturated resin;

(3) leaching the rare earth ions in the saturated resin in the step (2), wherein the leaching agent is a saturated ammonium chloride solution to obtain a rare earth-rich leaching solution;

(4) precipitating the rare earth-rich eluent obtained in the step (3), adding the rare earth-rich eluent into 100g/L ammonium bicarbonate solution, preserving the heat for 1h at 90 ℃, and filtering to obtain rare earth salt precipitate;

(5) and (4) roasting the rare earth salt precipitate obtained in the step (4) at 1000 ℃ for 1h to obtain the mixed rare earth oxide.

Comparative example 1

Leaching rare earth elements Y and Eu in red powder, and detecting the leaching rate of the rare earth elements under the conditions of stirring speed of 800rpm, hydrochloric acid concentration of 4mol/L, hydrogen peroxide addition of 0.2mL/g, reaction temperature of 60 ℃, liquid-solid ratio of 7.5mL/g and reaction time of 3 hours.

Comparative example 2

The same operation as that of example 2, except that in step (1), the waste phosphor was mixed with the ethylenediamine tetraacetic acid solution with a concentration of 2mmol/L, and the solid-to-liquid ratio of the waste phosphor to the ethylenediamine tetraacetic acid solution was 1 g: 200mL, adjusting the pH value of the reaction system to 5 by adopting a buffer solution, reacting for 4 hours at the temperature of 50 ℃, and filtering to obtain rare earth leachate and leaching residues.

Comparative example 3

The operation steps are the same as those of example 2, except that in step (1), the waste fluorescent powder is placed in a microwave reactor, the reaction system is adjusted to pH 5 by using a buffer solution, and the reaction system is filtered after reacting for 4 hours under the conditions of the microwave power of 1000W and the temperature of 50 ℃ to obtain rare earth leachate and leaching residues.

The leaching methods of examples 1 to 3 of the present invention have similar leaching rates of heavy metals and results are parallel to each other, and the following examples 2 are compared with comparative example 1 using a conventional acid leaching method, example 2 using only a chelating agent, and example 3 using only microwaves, and the contents of leached rare earth elements are studied, and the specific results are shown in table 1:

TABLE 1 rare earth element leaching rate control table (in mass percent)

In example 2, strong acid cation exchange resin is used for ion exchange, ammonium sulfate leaching and oxalic acid precipitation, so that the recovery rate of the rare earth elements reaches 90.32%, and the purity of the rare earth oxide obtained after the oxalic acid precipitation and roasting is 99.36%;

compared with the comparative example 1, the leaching rates of the rare earth elements of Y and Eu in the embodiment 2 are not greatly different, which shows that the leaching rates of Ce and Tb are obviously superior to those of the prior art after the technical defects and problems of the prior art are overcome, and the technical problem that the rare earth elements of Ce and Tb are difficult to leach in the prior art is overcome; compared with comparative examples 2 and 3, the sum of the leaching rates of comparative examples 2 and 3 is obviously smaller than the combined action of the microwave-chelating agent of example 2, which shows that the two are not simply combined but can generate the mutual cooperation effect, thereby achieving the unexpected technical effect.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.