CN115094239B - Method for recovering rare earth elements from waste fluorescent powder, alkali flux and application of alkali flux as doping element in preparation of manganese-zinc ferrite - Google Patents
Method for recovering rare earth elements from waste fluorescent powder, alkali flux and application of alkali flux as doping element in preparation of manganese-zinc ferrite Download PDFInfo
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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
- C22B7/007—Wet processes by acid leaching
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F17/00—Compounds of rare earth metals
- C01F17/20—Compounds containing only rare earth metals as the metal element
- C01F17/206—Compounds containing only rare earth metals as the metal element oxide or hydroxide being the only anion
- C01F17/224—Oxides or hydroxides of lanthanides
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F17/00—Compounds of rare earth metals
- C01F17/20—Compounds containing only rare earth metals as the metal element
- C01F17/206—Compounds containing only rare earth metals as the metal element oxide or hydroxide being the only anion
- C01F17/224—Oxides or hydroxides of lanthanides
- C01F17/235—Cerium oxides or hydroxides
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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
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/02—Roasting processes
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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
- C22B59/00—Obtaining rare earth metals
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
The invention provides a method for recovering rare earth elements from waste fluorescent powder, an alkali flux and application of the alkali flux as a doping element in the preparation of manganese-zinc ferrite, wherein the alkali flux comprises the following components in percentage by weight: 50-60% of extraction flux and KBe of low-temperature fluxing agent 2 F 5 35 to 45 percent of low-temperature flowing agent KAlF 4 5 to 15 percent of the solvent, and the extraction flux is Na 3 AlF 6 Or K 3 AlF 6 Or NaAlF 4 . The reduction of the melting temperature and the reduction of the melting time greatly reduce the energy consumption for extracting the rare earth elements from the waste fluorescent powder, and the economic benefit is obvious; the roasting conversion process of the rare earth fluoride is completed by cooling treatment in the molten salt extraction process, and compared with the prior art, the method reduces the energy consumption and shortens the subsequent separation time of the rare earth elements.
Description
Technical Field
The invention belongs to the field of recycling of industrial wastes, and particularly relates to a method for recovering rare earth elements from waste fluorescent powder, an alkali flux and application of the alkali flux as a doping element in preparation of manganese-zinc ferrite.
Background
The rare earth fluorescent powder is usually coated on the inner wall of a fluorescent lamp in a thin layer, and the contained rare earth elements of yttrium (Y), europium (Eu), terbium (Tb) and cerium (Ce) are basic raw materials of high-tech rare earth functional materials and are strategic rare earth elements which are in the critical shortage of China, wherein Y, eu and Tb are also positioned in 5 most critical rare earth listed in the United states energy agency. With the increasing application of rare earth elements in the field of illumination, the quantity of waste rare earth fluorescent powder is also increasing continuously, and the waste rare earth fluorescent powder is a potential secondary resource, so that the rare earth resource is effectively and reasonably utilized, the rare earth resource can be recycled, and the pollution of the waste rare earth fluorescent powder to the environment is reduced.
The rare earth fluorescent powder comprises red powder, green powder and blue powder which are respectively a phosphate system, an aluminate system, a borate system and a silicate system. Among them, aluminate systems are becoming the most widely used fluorescent powder system in the world due to their characteristics of ultraviolet aging resistance, stability at high temperature, high ultraviolet sensitivity, high luminous efficiency, etc. In order to recover the valuable rare earth in the aluminate system, the fluorescent powder mixture needs to be treated by acid dissolution and alkali fusion. Red powder (Y) of aluminate system 2 O 3 :Eu 3+ ) The rare earth elements in the product exist in the form of oxides, and Y and Eu in the product are easy to be leached by acid; green powder (MgAl) 11 O 19 ：Ce 3+ ，Tb 3+ ) And blue powder (BaMgAl) 10 O 17 ：Eu 2+ ) The magnesium aluminate spinel structure has strong acid resistance, tb, ce and Eu are difficult to directly leach by acid, the crystal structure of the Tb, ce and Eu is damaged by adopting alkali fusion pretreatment, and then rare earth elements in the Tb, ce and Eu can be effectively recovered by adopting acid leaching.
The alkali fusion pretreatment is to melt metal resources at high temperature by using alkaline molten salt as a medium and usually using sodium hydroxide, potassium hydroxide, sodium salt and potassium salt as single or mixed flux, and can effectively destroy the crystal structures of green powder and blue powder of an aluminate system. The alkali fusion pretreatment belongs to a complex heterogeneous reaction process, needs higher reaction temperature and longer reaction time for improving the recovery rate of the smelting metal, has the problems of high energy consumption, high recovery cost, high alkali consumption and the like, and is not beneficial to the low-cost recycling of rare earth resources in the waste fluorescent powder.
Disclosure of Invention
In view of the problems of the prior art, a first object of the present invention is to provide an alkali flux for recovering rare earth elements from waste phosphor, and a second object of the present invention is to provide a method for recovering rare earth elements from waste phosphor. Green powder and blue powder suitable for aluminate system.
In order to achieve the first object, the invention is realized by the following technical scheme: an alkali flux for recovering rare earth elements from waste fluorescent powder is characterized by comprising the following components in percentage by weight: 50-60% of extraction flux and KBe of low-temperature fluxing agent 2 F 5 35 to 45 percent of low-temperature flowing agent KAlF 4 5 to 15 percent of the solvent, and the extraction flux is Na 3 AlF 6 Or K 3 AlF 6 Or NaAlF 4 。
Preferably, the following components: the composition consists of the following components in percentage by weight: 50% of extraction flux and KBe of low-temperature flux 2 F 5 40% low temperature flowing agent KAlF 4 10％。
The second object of the present invention is achieved by: a method for recovering rare earth elements from waste fluorescent powder is characterized by comprising the following steps:
the method comprises the following steps:
1) Fully and uniformly mixing the alkali flux and the waste fluorescent powder as described in any one of claims 1-2;
2) Placing the mixed material in a muffle furnace for high-temperature roasting, wherein a liquid phase appears when the temperature reaches about 330 ℃, continuously heating to 700-900 ℃ and keeping for 1-2 hours, so that solid-liquid layering appears on the material, wherein impurities such as magnesium, barium and the like exist in a solid phase, rare earth elements exist in a liquid phase in a fluoride form, and performing solid-liquid separation to separate impurities such as magnesium, barium and the like;
3) Cooling the liquid molten salt to 350-400 ℃, adding alkali, continuing to roast for 1-2 h, cooling to room temperature after alkali fusion is completed, adding water into the molten salt, washing off water-soluble salts such as fluorine, aluminum, beryllium, potassium, sodium and the like, filtering, and washing a filter cake with water;
4) And (3) stirring and hot-dipping the filter cake at the temperature of 70 ℃ by using dilute hydrochloric acid, wherein the leaching solution is a rare earth element chloride solution.
In the scheme, the method comprises the following steps: the mass ratio of the alkali flux to the waste fluorescent powder is 5.
In the scheme, the method comprises the following steps: in the step 3), the mass ratio of the added alkali to the liquid molten salt after solid-liquid separation is 1.
In the scheme, the method comprises the following steps: the alkali is sodium hydroxide or potassium hydroxide.
In step 2), the extraction flux is Na 3 AlF 6 When the temperature is raised to 900 ℃, the extraction flux is K 3 AlF 6 When the temperature is raised to 800 ℃, the extraction flux is NaAlF 4 When the temperature is increased to 700 ℃.
The extracted rare earth elements are used as doping elements in the preparation of manganese-zinc ferrite.
Flow agent KAlF of the invention 4 With fluxing agent KBe 2 F 5 The binary system of the composition belongs to the eutectic type, KAlF 4 And KBe 2 F 5 Are of similar structural properties, KAlF 4 Melting point of 575 deg.C, KBe 2 F 5 The melting point of 359 ℃ and the eutectic point of the two is 330 ℃, the liquid phase appears and starts to melt and flow under the condition of low temperature, the melting quantity is gradually increased along with the increase of the temperature, the flow between the mixed materials is accelerated, and particularly, the flowing agent KAlF 4 The super-fluid property of the material can flow between the mixed materials without resistance, and the mass transfer and heat transfer efficiency between the materials is improved; at the same time, KBe 2 F 5 Thermal decomposition into KF and BeF 2 In which KF dissociates in the melt to produce K + And F - All exhibit strong corrosion characteristics, at K + Extremely strong permeability and F - Under the dual action of extremely strong fluidity, the rare earth in the waste fluorescent powder is subjected to fluorination reaction rapidly to generate rare earth fluoride. At the same time, flux (Na) is extracted in a molten state 3 AlF 6 Or K 3 AlF 6 Or NaAlF 4 ) All can destroy aluminateThe aluminum spinel blocks in the waste fluorescent powder are structured, so that the aluminum spinel blocks are melted in the extraction flux. To reduce KAlF 4 Volatilizing, the reaction temperature of the molten salt system is lower than KAlF 4 The gasification temperature is not more than 900 ℃.
In order to reduce the energy consumption of roasting and converting the rare earth fluoride, the original heat of the molten salt is fully utilized, after solid-liquid separation of the liquid molten salt, naOH or KOH is added when the temperature of the liquid molten salt is reduced to 350-400 ℃, and the roasting is carried out for 1-2 hours at the temperature of 1. In the process, the flowing agent KAlF is still fully utilized 4 With fluxing agent KBe 2 F 5 The fluidity and permeability of the pseudo binary system avoid the operation that sodium hydroxide is added after cooling and crushing and then the temperature is raised again in the prior art, thereby realizing the uninterrupted continuous operation of molten salt extraction and alkali fusion conversion, reducing the energy consumption and shortening the recovery time.
Has the advantages that:
by adopting the molten salt system, the recovery rate of extracting rare earth elements from the waste fluorescent powder is over 98 percent by controlling the melting temperature, the melting time, the proportion of the waste fluorescent powder to the molten salt and the proportion of each component of the molten salt; the melting temperature is reduced by 200-500 ℃ compared with a single alkali melting system, and the melting time is shortened to 1-2 h; the reduction of the melting temperature and the reduction of the melting time greatly reduce the energy consumption for extracting the rare earth elements from the waste fluorescent powder, and the economic benefit is obvious; the roasting conversion process of the rare earth fluoride is completed by cooling treatment in the molten salt extraction process, and compared with the prior art, the method reduces the energy consumption and shortens the subsequent separation time of the rare earth elements.
An alkali flux for recovering rare earth elements from waste fluorescent powder is characterized by comprising the following components in percentage by weight: 50-60% of extraction flux and KBF of low-temperature fluxing agent 4 35 to 45 percent of low-temperature flowing agent KAlF 4 5 to 15 percent of the solvent, and the extraction flux is Na 3 AlF 6 Or K 3 AlF 6 Or NaAlF 4 。
A method for recovering rare earth elements from waste fluorescent powder is characterized by comprising the following steps:
1) Fully and uniformly mixing the alkali flux and the waste fluorescent powder according to the mass ratio of 5;
2) Placing the mixed material in a muffle furnace for high-temperature roasting, wherein a liquid phase appears when the temperature reaches about 470 ℃, continuously heating to 700-900 ℃ and keeping for 1-2 hours, so that solid-liquid layering appears on the material, wherein impurities such as magnesium, barium and the like exist in a solid phase, rare earth elements exist in a liquid phase in a fluoride form, and performing solid-liquid separation to separate impurities such as magnesium, barium and the like;
3) Cooling liquid molten salt to room temperature, crushing to 200 meshes, adding NaOH or KOH according to a mass ratio of 1;
4) And (3) stirring and hot-dipping the filter cake at the temperature of 70 ℃ by using dilute hydrochloric acid, wherein the leaching solution is a rare earth element chloride solution.
When KBF is adopted 4 Their principle of action with KBe 2 F 5 Same because of KBF 4 Is around 470 ℃, thus the process steps and the KBe 2 F 5 Different. Similarly, when the extraction flux is Na 3 AlF 6 When the temperature is raised to 900 ℃, the extraction flux is K 3 AlF 6 When the temperature is raised to 800 ℃, the extraction flux is NaAlF 4 When the temperature is increased to 700 ℃.
Detailed Description
The present invention will be further described with reference to the following examples.
Example 1
An alkali flux for recovering rare earth elements from waste fluorescent powder comprises the following components in percentage by weight: extraction of flux Na 3 AlF 6 50% low temperature flux KBe 2 F 5 40% of low-temperature flowing agent KAlF 4 10％。
A method for recovering rare earth elements from waste fluorescent powder,
1) Mixing alkali flux and waste fluorescent powder (green powder MgAl) 11 O 19 ：Ce 3+ ，Tb 3+ ) Fully mixing according to a mass ratio of 5Mixing uniformly.
2) Placing the mixed material in a muffle furnace for high-temperature roasting, continuously heating to 900 ℃ to generate a liquid phase when the temperature reaches about 330 ℃, keeping for 1-2 hours, and allowing the material to have solid-liquid stratification, wherein impurities such as magnesium and barium exist in the solid phase, rare earth elements exist in the liquid phase in the form of fluoride, and performing solid-liquid separation (pouring out upper-layer molten salt) to separate impurities such as magnesium and barium.
3) Cooling the liquid molten salt to 350-400 ℃, adding sodium hydroxide, continuing to roast for 1-2 h, carrying out alkali fusion conversion on rare earth fluoride, wherein aluminum exists in the form of sodium metaaluminate and beryllium exists in the form of sodium metaberyllium, cooling to room temperature after the alkali fusion conversion is finished, adding water, washing to remove water-soluble salts such as fluorine, aluminum, beryllium, potassium, sodium and the like, filtering, and washing a filter cake with water; the mass ratio of the supplemented sodium hydroxide to the liquid molten salt after solid-liquid separation is 1.
4) And (3) stirring and hot-dipping the filter cake at 70 ℃ by using dilute hydrochloric acid, wherein the leaching solution is a rare earth element chloride solution, and the impurity content is less than 0.5%.
After the leachate is concentrated and enriched, a single rare earth element chloride solution, a cerium chloride solution and a terbium chloride solution can be separated by using P507 extraction resin.
After the pure single rare earth solution is separated, the cerium chloride solution and the terbium chloride solution are respectively added with oxalic acid for precipitation to obtain cerium oxalate and terbium oxalate, the cerium oxalate is calcined in a rotary kiln for 1.5 to 2.5 hours at the temperature of between 350 and 400 ℃ to obtain pure cerium oxide, the terbium oxalate is calcined in the rotary kiln for 12 to 15 hours at the temperature of between 1000 and 1050 ℃ to obtain pure terbium oxide, the purity is 99.5 percent, and the recovery rate is 98 percent. The extracted rare earth elements can be used as doping elements in the preparation of manganese-zinc ferrite.
Example 2
An alkali flux for recovering rare earth elements from waste fluorescent powder comprises the following components in percentage by weight: extraction flux K 3 AlF 6 60% low-temperature fluxing agent KBe 2 F 5 35% of low-temperature flowing agent KAlF 4 5％。
1) Fluxing agent, waste fluorescent powder (blue powder (BaMgAl) 10 O 17 ：Eu 2+ ) And (2) according to the mass ratio of 5.
2) And (2) placing the mixed material in a muffle furnace for high-temperature roasting, wherein a liquid phase appears when the temperature reaches about 330 ℃, continuously heating to 800 ℃ and keeping for 1-2 hours, so that solid-liquid layering appears on the material, impurities such as magnesium and barium exist in the solid phase, rare earth elements exist in the liquid phase in the form of fluoride, and the impurities such as magnesium and barium are separated out through solid-liquid separation.
3) Cooling the liquid molten salt to 350-400 ℃, adding potassium hydroxide, continuing roasting for 1-2 hours, carrying out alkali fusion conversion on rare earth fluoride, allowing aluminum to exist in the form of potassium metaaluminate and beryllium to exist in the form of potassium metaberyllide, cooling to room temperature after the alkali fusion is finished, adding water, washing to remove water-soluble salts such as fluorine, aluminum, beryllium, potassium, sodium and the like, filtering, washing a filter cake with water, and controlling the mass ratio of the added potassium hydroxide to the whole reaction system to be 1.
4) And (3) stirring and hot-dipping the filter cake at 70 ℃ by adopting 5mol/L hydrochloric acid, wherein the leaching solution is a rare earth element solution europium chloride, and the impurity content is less than 0.5%.
Adding oxalic acid into the obtained europium chloride solution for precipitation to obtain europium oxalate, and calcining the europium oxalate in a rotary kiln at the temperature of between 750 and 900 ℃ for 2 to 4 hours to obtain pure europium oxide with the purity of 99.5 percent and the recovery rate of 98 percent.
Example 3
An alkali flux for recovering rare earth elements from waste fluorescent powder comprises the following components in percentage by weight: extraction flux NaAlF 4 60% low-temperature fluxing agent KBe 2 F 5 35% low temperature flowing agent KAlF 4 5％。
1) Fluxing agent, waste fluorescent powder (blue powder (BaMgAl) 10 O 17 ：Eu 2+ ) And (3) and mixing the components uniformly according to the mass ratio of 5.
2) Placing the mixed material in a muffle furnace for high-temperature roasting, continuously heating to 700 ℃ to generate a liquid phase when the temperature reaches about 330 ℃, keeping for 1-2 h, and allowing the material to generate solid-liquid layering, wherein impurities such as magnesium, barium and the like exist in the solid phase, rare earth elements exist in the liquid phase in the form of fluoride, and performing solid-liquid separation to separate the impurities such as magnesium, barium and the like.
3) Cooling the liquid molten salt to 350-400 ℃, adding sodium hydroxide, continuing to roast for 1-2 h, converting rare earth fluoride, allowing aluminum to exist in the form of sodium metaaluminate and beryllium to exist in the form of sodium metaberyllium, cooling to room temperature after completing alkali fusion, adding water, washing to remove water-soluble salts such as fluorine, aluminum, beryllium, potassium, sodium and the like, filtering, and washing a filter cake with water; the mass ratio of the supplemented sodium hydroxide to the liquid molten salt after solid-liquid separation is 1.
4) And (3) stirring and hot-dipping the filter cake at 70 ℃ by adopting 5mol/L hydrochloric acid, wherein the leaching solution is a rare earth element solution europium chloride, and the impurity content is less than 0.5%.
Adding oxalic acid into the obtained europium chloride solution for precipitation to obtain europium oxalate, and then calcining the europium oxalate in a rotary kiln at the temperature of 700-900 ℃ for 2-4 h to obtain pure europium oxide with the purity of 99.5 percent and the recovery rate of 98 percent.
Example 4
An alkali flux for recovering rare earth elements from waste fluorescent powder comprises the following components in percentage by weight: extraction of flux Na 3 AlF 6 50% low temperature flux KBF 4 40% of low-temperature flowing agent KAlF 4 10％。
A method for recovering rare earth elements from waste fluorescent powder,
1) Mixing alkali flux and waste fluorescent powder (green powder MgAl) 11 O 19 ：Ce 3+ ，Tb 3+ ) And (3) fully and uniformly mixing according to the mass ratio of 5.
2) Placing the mixed material in a muffle furnace for high-temperature roasting, wherein a liquid phase appears when the temperature reaches about 470 ℃, continuously heating to 900 ℃ and keeping for 1-2 h, the material is subjected to solid-liquid layering, impurities such as magnesium, barium and the like exist in the solid phase, rare earth elements exist in the liquid phase in the form of fluoride, and the impurities such as magnesium, barium and the like are separated through solid-liquid separation.
3) Cooling the liquid molten salt to room temperature, crushing to 200 meshes, and mixing the molten salt with the powder according to a mass ratio of 1:1, adding NaOH, roasting at the temperature of 350-400 ℃ for 1-2 h, cooling to room temperature after alkali fusion conversion is finished, adding water, washing to remove water-soluble salts such as fluorine, aluminum, potassium, sodium and the like, filtering, and washing a filter cake with water;
4) And (3) stirring and hot dipping the filter cake at 70 ℃ by using dilute hydrochloric acid, wherein the leaching solution is a rare earth element chloride solution, a cerium chloride solution and a terbium chloride solution, and the impurity content is less than 0.5%.
Concentrating and enriching the leachate, and separating a single rare earth element chloride solution, a cerium chloride solution and a terbium chloride solution by using P507 extraction resin.
After the pure single rare earth solution is separated, the cerium chloride solution and the terbium chloride solution are respectively added with oxalic acid for precipitation to obtain cerium oxalate and terbium oxalate, the cerium oxalate is calcined in a rotary kiln for 1.5 to 2.5 hours at the temperature of 350 to 400 ℃ to obtain pure cerium oxide, and the terbium oxalate is calcined in the rotary kiln for 12 to 15 hours at the temperature of 1000 to 1050 ℃ to obtain pure terbium oxide, wherein the purity is 99.5 percent, and the recovery rate is 98 percent. The extracted rare earth elements can be used as doping elements in the preparation of manganese-zinc ferrite.
Example 5
An alkali flux for recovering rare earth elements from waste fluorescent powder comprises the following components in percentage by weight: extraction flux NaAlF 4 60% low temperature flux KBF 4 35% of low-temperature flowing agent KAlF 4 5％。
1) Fluxing agent, waste fluorescent powder (blue powder (BaMgAl) 10 O 17 ：Eu 2+ ) And (2) according to the mass ratio of 5.
2) And (2) placing the mixed material in a muffle furnace for high-temperature roasting, wherein a liquid phase appears when the temperature reaches about 330 ℃, continuously heating to 700 ℃ and keeping for 1-2 hours, so that solid-liquid layering appears on the material, impurities such as magnesium and barium exist in the solid phase, rare earth elements exist in the liquid phase in the form of fluoride, and performing solid-liquid separation to separate the impurities such as magnesium and barium.
3) Cooling the liquid molten salt to room temperature, crushing to 200 meshes, and mixing the molten salt with the powder according to a mass ratio of 1:1 adding KOH, roasting at 350-400 ℃ for 1-2 h, cooling to room temperature after alkali fusion is finished, adding water, washing to remove water-soluble salts such as fluorine, aluminum, potassium, sodium and the like, filtering, and washing a filter cake with water.
4) And (3) stirring and hot-dipping the filter cake at 70 ℃ by adopting 5mol/L hydrochloric acid, wherein the leaching solution is a rare earth element solution europium chloride, and the impurity content is less than 0.5%.
Adding oxalic acid into the obtained europium chloride solution for precipitation to obtain europium oxalate, and calcining the europium oxalate in a rotary kiln at the temperature of between 700 and 900 ℃ for 2 to 4 hours to obtain pure europium oxide with the purity of 99.5 percent and the recovery rate of 98 percent.
Example 6
An alkali flux for recovering rare earth elements from waste fluorescent powder comprises the following components in percentage by weight: extraction flux K 3 AlF 6 50% low temperature flux KBF 4 40% of low-temperature flowing agent KAlF 4 10％。
1) Fluxing agent, waste fluorescent powder (blue powder (BaMgAl) 10 O 17 ：Eu 2+ ) And (3) and mixing the components uniformly according to the mass ratio of 5.
2) The mixed material is put into a muffle furnace for high-temperature roasting, liquid phase appears when the temperature reaches about 330 ℃, the temperature is continuously raised to 800 ℃ and kept for 1-2 hours, solid-liquid delamination appears in the material, wherein impurities such as magnesium, barium and the like exist in the solid phase, rare earth elements exist in the liquid phase in the form of fluoride, and the impurities such as magnesium, barium and the like are separated out through solid-liquid separation.
3) Cooling the liquid molten salt to room temperature, crushing to 200 meshes, and mixing the molten salt with the powder according to a mass ratio of 1:1 adding KOH, roasting at 350-400 ℃ for 1-2 h, cooling to room temperature after alkali fusion is finished, adding water, washing to remove water-soluble salts such as fluorine, aluminum, potassium, sodium and the like, filtering, and washing a filter cake with water.
4) And (3) stirring and hot-dipping the filter cake at 70 ℃ by adopting 5mol/L hydrochloric acid, wherein the leaching solution is a rare earth element solution europium chloride, and the impurity content is less than 0.5%.
Adding oxalic acid into the obtained europium chloride solution for precipitation to obtain europium oxalate, and calcining the europium oxalate in a rotary kiln at the temperature of between 700 and 900 ℃ for 2 to 4 hours to obtain pure europium oxide with the purity of 99.5 percent and the recovery rate of 98 percent.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (6)
1. A method for recovering rare earth elements from waste fluorescent powder is characterized by comprising the following steps:
1) Fully and uniformly mixing the alkali flux and the waste fluorescent powder; the alkali fusing agent comprises the following components in percentage by weight: 50-60% of extraction flux and KBe of low-temperature fluxing agent 2 F 5 35 to 45 percent of low-temperature flowing agent KAlF 4 5 to 15 percent of the extraction flux is Na 3 AlF 6 Or K 3 AlF 6 Or NaAlF 4 ；
2) Placing the mixed material in a muffle furnace for high-temperature roasting, continuously heating to 700-900 ℃ to generate a liquid phase when the temperature reaches about 330 ℃, keeping for 1-2 hours, and allowing the material to generate solid-liquid stratification, wherein magnesium and barium impurities exist in a solid phase, rare earth elements exist in a liquid phase in a fluoride form, and performing solid-liquid separation to separate out magnesium and barium impurities;
3) Cooling the liquid molten salt to 350-400 ℃, adding alkali, continuing to roast for 1-2 h, cooling to room temperature after alkali fusion is completed, adding water into the molten salt, washing off fluorine, aluminum, beryllium, potassium and sodium water-soluble salt, filtering, and washing a filter cake with water;
4) And (3) stirring and hot-dipping the filter cake at the temperature of 70 ℃ by using dilute hydrochloric acid, wherein the leaching solution is a rare earth element chloride solution.
2. The method for recovering rare earth elements from waste fluorescent powder according to claim 1, wherein the method comprises the following steps: the alkali fusing agent comprises the following components in percentage by weight: 50% of extraction flux and KBe of low-temperature flux 2 F 5 40% of low-temperature flowing agent KAlF 4 10%。
3. The method for recovering rare earth elements from waste fluorescent powder according to claim 2, wherein the method comprises the following steps: the mass ratio of the alkali flux to the waste fluorescent powder is 5.
4. The method for recovering rare earth elements from waste fluorescent powder according to claim 3, wherein the method comprises the following steps: in the step 3), the mass ratio of the supplemented alkali to the liquid molten salt after solid-liquid separation is 1.
5. The method for recovering rare earth elements from waste fluorescent powder according to claim 4, wherein the method comprises the following steps: the alkali is sodium hydroxide or potassium hydroxide.
6. The method for recovering rare earth elements from waste fluorescent powder according to claim 5, wherein in the step 2), the extraction flux is Na 3 AlF 6 When the temperature is raised to 900 ℃, the extraction flux is K 3 AlF 6 When the temperature is raised to 800 ℃, the extraction flux is NaAlF 4 When the temperature is increased to 700 ℃.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202310160793.2A CN116287720B (en) | 2022-07-11 | 2022-07-11 | Process for recovering rare earth element from waste fluorescent powder and application of rare earth element in preparing Mn-Zn ferrite as doping element |
| CN202210810538.3A CN115094239B (en) | 2022-07-11 | 2022-07-11 | Method for recovering rare earth elements from waste fluorescent powder, alkali flux and application of alkali flux as doping element in preparation of manganese-zinc ferrite |
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| CN202210810538.3A CN115094239B (en) | 2022-07-11 | 2022-07-11 | Method for recovering rare earth elements from waste fluorescent powder, alkali flux and application of alkali flux as doping element in preparation of manganese-zinc ferrite |
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| WO2021133106A1 (en) * | 2019-12-27 | 2021-07-01 | 한국생산기술연구원 | Method for recovering rare earth metal |
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| 吴根华等.赝二元系KBe2F5-KAlF4 和 KBe2F5-K3AlF6的相图研究.安庆师范学院学报(自然科学版).2003,09(01),30-33. * |
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