CN108517426B - Method for efficiently separating and recycling rare earth in waste CRT fluorescent powder under mild condition - Google Patents

Method for efficiently separating and recycling rare earth in waste CRT fluorescent powder under mild condition Download PDF

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CN108517426B
CN108517426B CN201810462363.5A CN201810462363A CN108517426B CN 108517426 B CN108517426 B CN 108517426B CN 201810462363 A CN201810462363 A CN 201810462363A CN 108517426 B CN108517426 B CN 108517426B
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rare earth
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fluorescent powder
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hydrogen peroxide
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CN108517426A (en
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王维
吴玉锋
潘德安
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Beijing University of Technology
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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
    • 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
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

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  • Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)

Abstract

A method for efficiently separating and recovering rare earth in waste CRT fluorescent powder under mild conditions belongs to the field of rare earth resource recovery. Mechanically activating waste CRT fluorescent powder by ball milling; performing pressure leaching on the activated CRT fluorescent powder waste under the catalytic oxidation condition by using low-concentration sulfuric acid and hydrogen peroxide as a leaching agent to obtain a mixed leaching solution containing rare earth elements; enriching and recovering rare earth yttrium and europium by adopting a two-step precipitation method, and performing secondary extraction by using low-concentration hydrochloric acid to obtain rare earth leachate; and finally, efficiently separating and recovering europium and yttrium by adopting a photochemical method combined with a chemical precipitation method. The method can rapidly complete leaching of rare earth elements in low-concentration acid liquor, directly and efficiently separate and recover rare earth in the subsequent process by adopting a two-step precipitation method and a photochemical method, and can effectively prevent direct strong acid leaching from generating H2S gas pollutes the secondary pollution problem of the environment, the resource utilization rate of the whole process flow is high, and the harm to the health of operators in the waste disposal process is reduced as much as possible.

Description

Method for efficiently separating and recycling rare earth in waste CRT fluorescent powder under mild condition
Technical Field
The invention belongs to the technical field of rare earth resource recycling, and particularly relates to a method for efficiently separating and recycling rare earth in waste CRT fluorescent powder under mild conditions.
Background
With the increasingly rapid updating and upgrading of electronic products, a CRT display is gradually replaced by a new liquid crystal display, so that a large number of CRT displays enter a scrapping stage, according to statistics, one CRT approximately contains 15g of fluorescent powder, wherein the content of rare earth elements accounts for more than 20% of the quality of the CRT fluorescent powder, at present, most of the waste CRT fluorescent powder in China is buried or discarded at will, and the direct influence caused by the disposal mode is environmental pollution and resource waste.
Because the proportion of the fluorescent screen glass and the cone tube glass in the CRT display exceeds 89 percent and the CRT display contains heavy metal lead, the treatment research of the CRT in China is mainly focused on recycling the glass part, and the waste CRT fluorescent powder is not treated on a large scale. At present, the prior research process for treating the waste CRT fluorescent powder in China generally comprises direct strong acid leaching or acid leaching after high-temperature alkali fusion, the two methods need to adopt strong acid or strong base, the calcination time in the whole treatment process is long, the leaching process is complex, the introduction of the strong acid causes rapid corrosion of equipment, and the personnel operate the equipmentThe risk is high, and simultaneously, because the main components of a large amount of waste CRT fluorescent powder on the market are yttrium (europium) sulfide and zinc sulfide, if the direct enhanced acid leaching is carried out under open conditions, a large amount of H can be generated2S gas causes secondary pollution to the environment. Moreover, only some researches on the recovery of rare earth from CRT fluorescent powder waste mainly focus on recovering rare earth enrichment, and subsequent separation and purification processes are not involved.
Disclosure of Invention
Based on the defects of the technology, the invention aims to provide a method for efficiently separating and recycling rare earth in waste CRT fluorescent powder under mild conditions. The method adopts a mechanical activation auxiliary pressure catalytic oxidation leaching method, can utilize low-concentration acid to rapidly and efficiently leach rare earth elements in a short time, adopts a photochemical method combined with a chemical precipitation method to efficiently separate the rare earth elements, and can effectively prevent direct strong acid leaching from generating H2S gas pollutes the secondary pollution problem of the environment, the resource utilization rate of the whole process flow is high, and the harm to the health of operators in the waste disposal process is reduced as much as possible.
The invention provides a method for efficiently separating and recycling rare earth in waste CRT fluorescent powder under mild conditions, which is characterized by comprising the following steps:
(1) mechanical activation treatment: and mechanically activating the waste CRT fluorescent powder by high-energy ball milling under the wet milling condition, wherein the added pure water amount of the wet milling is 40-50% of the weight of the powder, the wet milling time is 2-3h, and fully drying in a drying oven after the wet milling to obtain the activated CRT fluorescent powder waste.
(2) Pressure catalytic oxidation leaching: taking the CRT fluorescent powder waste obtained in the step (1), fully mixing the CRT fluorescent powder waste with low-concentration sulfuric acid and hydrogen peroxide, putting the mixture into a polymerization reaction kettle for carrying out pressurized catalytic oxidation liquid-phase leaching reaction, controlling the reaction time to be 40-45min, the reaction temperature to be 60-70 ℃, and the liquid-solid mass ratio to be (18-23): 1, the concentration of sulfuric acid is 3.5-4.0mol/L, and after the reaction is finished, the polymerization reaction kettle is taken out and cooled to room temperature. Wherein the ratio of hydrogen peroxide: volume ratio of sulfuric acid (0.05-0.07): 1.
(3) enriching and recovering rare earth by a two-step precipitation method: adding ammonia water and hydrogen peroxide into the leachate obtained in the step (2), and controlling the ammonia water: the volume ratio of the hydrogen peroxide is (9-10): 1, adjusting the concentration of ammonia water to 6-7mol/L, adjusting the pH value to 9-10, and performing solid-liquid separation after primary precipitation; adding dilute hydrochloric acid into the solid obtained by the primary precipitation for dissolving to obtain a rare earth enrichment solution, then adding oxalic acid, adjusting the pH value to 1.8-2, boiling, and standing at room temperature for 10-12h to obtain the rare earth oxalate enrichment. Then adding dilute hydrochloric acid for secondary extraction to obtain rare earth leachate. Wherein the concentration of oxalic acid is 1.0-1.2mol/L, and the concentration of dilute hydrochloric acid is 3-4 mol/L.
(4) Separating and recovering rare earth europium by a photochemical method: adding isopropanol, ammonium sulfate and hydrogen peroxide into the leachate obtained in the step (3) respectively, mixing thoroughly, removing oxygen by continuous bubbling of nitrogen, and controlling Eu in the solution3+The concentration is 0.08-0.12mol/L, the concentration of ammonium sulfate is 0.8-1.2mol/L, the concentration of isopropanol is 1.8-2.2mol/L, and the concentration of hydrogen peroxide is 0.04-0.07 mol/L. In the reaction process, a 120W mercury lamp (254nm) is used for illumination for 8-10h, a sample is taken out for centrifugal separation, distilled water is used for washing for 2-3 times, and europium sulfate precipitate is obtained after vacuum drying.
(5) Recovering rare earth yttrium by a chemical precipitation method: and (4) taking the filtrate obtained in the step (4) through centrifugal separation, and adding excessive oxalic acid until no precipitate is separated out, so as to obtain yttrium oxalate precipitate. Wherein the concentration of oxalic acid is 1.0-1.2 mol/L.
Detailed Description
Specific examples of the present invention will now be described below, but the embodiments of the present invention are not limited thereto.
[ example 1 ]
The procedure and steps of this example are as follows:
(1) mechanical activation treatment: and mechanically activating the waste CRT fluorescent powder by high-energy ball milling under the wet milling condition, wherein the added pure water amount is 40 percent of the weight of the powder in the wet milling process, the wet milling time is 2h, and fully drying in a drying oven after the wet milling process to obtain the activated CRT fluorescent powder waste.
(2) Pressure catalytic oxidation leaching: taking the CRT fluorescent powder waste obtained in the step (1), fully mixing the CRT fluorescent powder waste with low-concentration sulfuric acid and hydrogen peroxide, putting the mixture into a polymerization reaction kettle for carrying out pressurized catalytic oxidation liquid-phase leaching reaction, controlling the reaction time to be 45min, controlling the reaction temperature to be 70 ℃, and controlling the liquid-solid mass ratio to be 18: 1, the concentration of sulfuric acid is 3.5mol/L, and after the reaction is finished, the polymerization reaction kettle is taken out and cooled to room temperature. Wherein the ratio of hydrogen peroxide: the volume ratio of the sulfuric acid is 0.05: 1.
(3) enriching and recovering rare earth by a two-step precipitation method: adding ammonia water and hydrogen peroxide into the leachate obtained in the step (2), and controlling the ammonia water: the volume ratio of the hydrogen peroxide is 9: 1, adjusting the concentration of ammonia water to 6mol/L and the pH value to 10, and performing solid-liquid separation after primary precipitation; and adding dilute hydrochloric acid into the solid obtained by the primary precipitation for dissolving to obtain a rare earth enrichment solution, then adding oxalic acid, adjusting the pH value to 1.8, boiling, and standing at room temperature for 10 hours to obtain the rare earth oxalate enrichment. Then adding dilute hydrochloric acid for secondary extraction to obtain rare earth leachate. Wherein the concentration of oxalic acid is 1.0mol/L, and the concentration of dilute hydrochloric acid is 3 mol/L.
(4) Separating and recovering rare earth europium by a photochemical method: adding isopropanol, ammonium sulfate and hydrogen peroxide into the leachate obtained in the step (3) respectively, mixing thoroughly, removing oxygen by continuous bubbling of nitrogen, and controlling Eu in the solution3+The concentration is 0.08mol/L, the concentration of ammonium sulfate is 0.8mol/L, the concentration of isopropanol is 1.8mol/L, and the concentration of hydrogen peroxide is 0.04 mol/L. In the reaction process, a 120W mercury lamp (254nm) is used for illumination for 8h, a sample is taken out for centrifugal separation, distilled water is used for washing for 3 times, and europium sulfate precipitate is obtained after vacuum drying.
(5) Recovering rare earth yttrium by a chemical precipitation method: and (4) taking the filtrate obtained in the step (4) through centrifugal separation, and adding excessive oxalic acid until no precipitate is separated out, so as to obtain yttrium oxalate precipitate. Wherein the concentration of oxalic acid is 1.0 mol/L.
In the embodiment, the extraction rates of the rare earth elements Y and Eu are both more than 99%.
[ example 2 ]
The procedure and steps of this example are as follows:
(1) mechanical activation treatment: and mechanically activating the waste CRT fluorescent powder by high-energy ball milling under the wet milling condition, wherein the added pure water amount is 50 percent of the weight of the powder in the wet milling process, the wet milling time is 2h, and fully drying in a drying oven after the wet milling process to obtain the activated CRT fluorescent powder waste.
(2) Pressure catalytic oxidation leaching: taking the CRT fluorescent powder waste obtained in the step (1), fully mixing the CRT fluorescent powder waste with low-concentration sulfuric acid and hydrogen peroxide, putting the mixture into a polymerization reaction kettle for carrying out pressurized catalytic oxidation liquid-phase leaching reaction, controlling the reaction time to be 45min, controlling the reaction temperature to be 60 ℃, and controlling the liquid-solid mass ratio to be 23: 1, the concentration of sulfuric acid is 4.0mol/L, and after the reaction is finished, the polymerization reaction kettle is taken out and cooled to room temperature. Wherein the ratio of hydrogen peroxide: the volume ratio of sulfuric acid is 0.07: 1.
(3) enriching and recovering rare earth by a two-step precipitation method: adding ammonia water and hydrogen peroxide into the leachate obtained in the step (2), and controlling the ammonia water: the volume ratio of hydrogen peroxide is 10: 1, adjusting the concentration of ammonia water to 7mol/L and the pH value to 9, and performing solid-liquid separation after primary precipitation; and adding dilute hydrochloric acid into the solid obtained by the primary precipitation for dissolving to obtain a rare earth enrichment solution, then adding oxalic acid, adjusting the pH value to 2, boiling, and standing at room temperature for 12 hours to obtain the rare earth oxalate enrichment. Then adding dilute hydrochloric acid for secondary extraction to obtain rare earth leachate. Wherein the concentration of oxalic acid is 1.2mol/L, and the concentration of dilute hydrochloric acid is 3 mol/L.
(4) Separating and recovering rare earth europium by a photochemical method: adding isopropanol, ammonium sulfate and hydrogen peroxide into the leachate obtained in the step (3) respectively, mixing thoroughly, removing oxygen by continuous bubbling of nitrogen, and controlling Eu in the solution3+The concentration is 0.12mol/L, the concentration of ammonium sulfate is 1.2mol/L, the concentration of isopropanol is 2.2mol/L, and the concentration of hydrogen peroxide is 0.07 mol/L. In the reaction process, a 120W mercury lamp (254nm) is used for illumination for 8h, a sample is taken out for centrifugal separation, distilled water is used for washing for 2 times, and europium sulfate precipitate is obtained after vacuum drying.
(5) Recovering rare earth yttrium by a chemical precipitation method: and (4) taking the filtrate obtained in the step (4) through centrifugal separation, and adding excessive oxalic acid until no precipitate is separated out, so as to obtain yttrium oxalate precipitate. Wherein the concentration of oxalic acid is 1.2 mol/L.
In the embodiment, the extraction rates of the rare earth elements Y and Eu are both more than 99%.

Claims (1)

1. A method for efficiently separating and recycling rare earth in waste CRT fluorescent powder under mild conditions is characterized by comprising the following technical processes and steps:
(1) mechanical activation treatment: mechanically activating waste CRT fluorescent powder by ball milling under the wet milling condition, wherein the added pure water amount of the wet milling is 40-50% of the weight of the powder, the wet milling time is 2-3h, and fully drying in a drying oven after the wet milling to obtain activated CRT fluorescent powder waste;
(2) pressure catalytic oxidation leaching: taking the CRT fluorescent powder waste obtained in the step (1), fully mixing the CRT fluorescent powder waste with low-concentration sulfuric acid and hydrogen peroxide, putting the mixture into a polymerization reaction kettle for carrying out pressurized catalytic oxidation liquid-phase leaching reaction, controlling the reaction time to be 40-45min, the reaction temperature to be 60-70 ℃, and the liquid-solid mass ratio to be (18-23): 1, the concentration of sulfuric acid is 3.5-4.0mol/L, after the reaction is finished, the polymerization reaction kettle is taken out and cooled to room temperature; wherein the ratio of hydrogen peroxide: volume ratio of sulfuric acid (0.05-0.07): 1;
(3) enriching and recovering rare earth by a two-step precipitation method: adding ammonia water and hydrogen peroxide into the leachate obtained in the step (2), and controlling the ammonia water: the volume ratio of the hydrogen peroxide is (9-10): 1, ammonia water with the concentration of 6-7mol/L, adjusting the pH value to 9-10, and performing solid-liquid separation after primary precipitation; adding dilute hydrochloric acid into the solid obtained by the primary precipitation for dissolving to obtain a rare earth enrichment solution, then adding oxalic acid, adjusting the pH value to 1.8-2, boiling, and standing at room temperature for 10-12h to obtain a rare earth oxalate enrichment substance; then adding dilute hydrochloric acid for secondary extraction to obtain rare earth leachate; wherein the concentration of oxalic acid is 1.0-1.2mol/L, and the concentration of dilute hydrochloric acid is 3-4 mol/L;
(4) separating and recovering rare earth europium by a photochemical method: adding isopropanol, ammonium sulfate and hydrogen peroxide into the leachate obtained in the step (3) respectively, mixing thoroughly, removing oxygen by continuous bubbling of nitrogen, and controlling Eu in the solution3+The concentration is 0.08-0.12mol/L, the concentration of ammonium sulfate is 0.8-1.2mol/L, the concentration of isopropanol is 1.8-2.2mol/L, and the concentration of hydrogen peroxide is 0.04-0.07 mol/L; in the reaction process, a 120W mercury lamp is used for illuminating for 8-10h, a sample is taken out for centrifugal separation, distilled water is used for washing for 2-3 times, and europium sulfate precipitate is obtained after vacuum drying;
(5) recovering rare earth yttrium by a chemical precipitation method: taking the filtrate obtained in the step (4) through centrifugal separation, and adding excessive oxalic acid until no precipitate is separated out, so as to obtain yttrium oxalate precipitate; wherein the concentration of oxalic acid is 1.0-1.2 mol/L.
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CN112553483B (en) * 2020-12-04 2022-05-17 江西理工大学 Method for leaching rare earth elements in waste fluorescent powder by using chelating agent
CN114703366B (en) * 2022-04-24 2023-03-17 中南大学 Method for treating waste CRT fluorescent powder by concentrated sulfuric acid directional transformation

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CN103397211A (en) * 2013-06-29 2013-11-20 北京工业大学 Rapid method for destroying structure of cathode-ray tube phosphor waste material
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