A method for recycling polishing powder

Abstract

This invention discloses a method for recovering polishing powder, belonging to the field of waste resource recycling technology, comprising the following steps: treating gravity-selected rare earth polishing powder in hydrochloric acid solution to obtain primary treated waste powder and primary untreated filtrate; adding lanthanum ion adsorbent to the primary untreated filtrate, stirring for 4-6 hours, centrifuging and filtering, washing the precipitate, desorbing for 24 hours, filtering, and obtaining secondary untreated filtrate; adding ammonia water to the secondary untreated filtrate to adjust the pH to 8-12, stirring evenly, stirring and reacting at 50-120℃ for 8-10 hours, cooling to room temperature, filtering to obtain precipitate, washing, drying, and calcining the precipitate to obtain recovered lanthanum oxide; placing the primary treated waste powder in sodium hydroxide solution, stirring and reacting at 105℃ for 1-1.5 hours, cooling, filtering with a vacuum filter, washing and drying the filter cake to obtain recovered cerium oxide; the rare earth oxide recovery rate obtained by the recovery method of this invention is high and the impurity content is low.

Description

Technical Field

[0001] This invention belongs to the field of waste resource recycling technology, specifically relating to a method for recycling polishing powder. Background Technology

[0002] Rare earth cerium-based polishing powder is currently the mainstream rare earth polishing powder. It has excellent polishing performance and can improve the surface finish of products or parts. It is known as the "king of polishing powders" and is widely used in the polishing of precision optical glass, picture tubes, displays, flat glass, crystal and consumer electronics products. However, after the polishing of rare earth polishing powder fails, it is often disposed of by landfill. Since rare earth is an important non-renewable resource, the recycling of waste rare earth polishing powder has become an inevitable trend.

[0003] Waste rare earth polishing powder contains elements such as La, Ce, Pr, Al and Si. The total amount of CeO2 and La2O3 is generally 40-80%, indicating a high rare earth content. It also contains impurities such as glass particles, glass fragments, polishing skin (organic polymers) from the polishing machine, metals or metal oxides, etc. The main impurities are silicon and aluminum impurities, which have a significant impact on the recycling and reuse of waste polishing powder.

[0004] Chinese patent CN109536037B discloses a method for removing silicon-aluminum impurities from waste rare earth polishing powder, including the following steps: providing waste rare earth polishing powder containing silicon-aluminum impurities; mixing the waste rare earth polishing powder and alkaline solution under the action of a grinding medium to obtain a slurry; heating the slurry to 50℃~80℃ under stirring conditions, filtering, and obtaining rare earth polishing powder with silicon-aluminum impurities removed. However, the removal effect of silicon-aluminum impurities is poor because the main impurities in the polishing powder fertilizer, alumina and silicon dioxide, will produce a precipitate called zeolite in an alkaline environment, which leads to the impurities not being completely removed and affects the impurity removal effect.

[0005] Chinese patent CN102391833B discloses a method for regenerating waste rare earth polishing powder used in crystal glass, which includes the following process: (1) using a screening device to coarsely screen the waste rare earth polishing powder to remove impurities and large particles; (2) adjusting the waste rare earth polishing powder into a slurry and using a gravity separation device to separate it into a high-content rare earth polishing powder waste; (3) then using a strong acid to chemically treat and dissolve the soluble substances; (4) roasting the waste at a high temperature above 800°C to remove the thermosetting resin and organic oil stains and increase the hardness of the rare earth polishing powder; (5) cooling and grinding the roasted material to achieve a particle size range that can be reused as polishing powder. The strong acid in this patent is dilute nitric acid or hydrofluoric acid. Hydrofluoric acid is a highly toxic substance that produces polluted wastewater that is difficult to treat and causes secondary pollution.

[0006] Based on the above description, providing an environmentally friendly and effective method for recycling polishing powder is a technical problem that needs to be solved. Summary of the Invention

[0007] The purpose of this invention is to provide a method for recycling polishing powder to solve the problems in the prior art.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] A method for recycling polishing powder includes the following steps:

[0010] Step S1: Pass the waste rare earth polishing powder through a 60-mesh sieve, then adjust the slurry, and use a shaking table gravity separation device for gravity separation. The heavy components obtained after separation are dried to obtain gravity-separated rare earth polishing powder.

[0011] Step S2: Place the heavy-selection rare earth polishing powder in a reaction vessel, add hydrochloric acid solution, control the temperature at 20-25℃, stir and react for 1-1.5h. After the reaction is completed, filter with a vacuum filter, wash the filter cake with deionized water until the washing liquid is neutral, dry at 100℃ to constant weight, collect the filtrate for later use, and obtain primary waste powder and primary filtrate to be treated.

[0012] Step S3: Add lanthanum ion adsorbent to the primary filtrate, stir for 4-6 hours, centrifuge and filter, discharge the filtrate, wash the precipitate with deionized water 3-5 times, transfer it to a 0.1 mol / L ethylenediaminetetraacetic acid solution for desorption for 24 hours, filter, collect the filtrate for later use, and obtain recyclable lanthanum ion adsorbent (filter cake) and secondary filtrate.

[0013] Step S4: Add ammonia to the secondary filtrate to adjust the pH to 8-12, stir evenly to form a precursor solution, control the temperature at 50-120℃, stir for 8-10 hours, cool to room temperature, filter to obtain precipitate, wash the precipitate with deionized water, dry at 80-90℃, and then calcine at 500-600℃ for 2-8 hours to obtain recovered lanthanum oxide.

[0014] Step S5: Place the primary waste powder in a reaction vessel, add sodium hydroxide solution, control the temperature at 105℃, stir and react for 1-1.5h. After the reaction is completed, cool to room temperature, filter with a vacuum filter, wash the filter cake with deionized water until the washing liquid is neutral, and dry at 100℃ to constant weight to obtain recovered cerium oxide.

[0015] Step S6: Mix the recovered lanthanum oxide obtained in step S4 and the recovered cerium oxide obtained in step S5, calcine at 1000-1100℃ for 3-6 hours, and then pulverize by airflow after cooling.

[0016] The rare earth oxides in waste rare earth polishing powder are cerium oxide and lanthanum oxide. Cerium oxide is almost insoluble in alkali and hydrochloric acid, but lanthanum oxide is soluble in hydrochloric acid. The main difficult-to-treat impurities are aluminum oxide and silicon dioxide, both of which are soluble in alkali and easily form zeolite precipitates in alkaline environments, which is not conducive to impurity removal. To address the above problems, this invention provides a method for recycling polishing powder. Through stepwise acid-alkali treatment and the recycling of rare earth ions, the method achieves efficient recovery of rare earth oxides in polishing powder, enabling the reuse of waste resources and saving production costs.

[0017] As a further technical solution of the present invention, the concentration of the slurry in step S1 is 25-35% by mass.

[0018] As a further technical solution of the present invention, in step S2, the mass ratio of heavy-selected rare earth polishing powder to hydrochloric acid solution is 0.5:1, and the concentration of hydrochloric acid solution is 1 mol / L.

[0019] As a further technical solution of the present invention, the ratio of the amount of the primary filtrate to be treated and the lanthanum ion adsorbent in step S3 is 30-50 mL: 10 mg.

[0020] As a further technical solution of the present invention, the mass fraction of ammonia in step S4 is 25-28%.

[0021] As a further technical solution of the present invention, in step S5, the mass ratio of sodium hydroxide solution to primary treated waste powder is 2:1, and the concentration of sodium hydroxide solution is 2.5 mol / L.

[0022] As a further technical solution of the present invention, the lanthanum ion adsorbent is prepared by the following steps:

[0023] Polyacrylamide was added to deionized water and stirred at 25°C for 3 hours. Then, lanthanum nitrate hexahydrate and glutaraldehyde aqueous solution were added and stirred for 5-10 minutes. Aldehyde-modified molecular sieves were then added, and the mixture was heated to 50°C and stirred for 5-6 hours. After the reaction was complete, the mixture was filtered, and the filter cake was washed in 0.1 mol / L ethylenediaminetetraacetic acid solution for 24 hours. This washing was repeated four times. The La content in the eluent was measured using FAAS (Flame Atomic Absorption Spectrometry). 3+ Concentration to ensure La 3+ The lanthanum ion adsorbent was completely removed, dried at 90°C to constant weight, and ground through an 80-100 mesh sieve.

[0024] As a further technical solution of the present invention, the ratio of polyacrylamide, deionized water, lanthanum nitrate hexahydrate, glutaraldehyde aqueous solution and aldehyde-modified molecular sieve is 0.4-0.5g: 50-60mL: 0.5g: 0.5g: 0.5-1g, and the mass fraction of glutaraldehyde aqueous solution is 25%. Using rare earth lanthanum ions as template ions, aldehyde-modified molecular sieve as matrix material, and polyacrylamide as functional monomer, the lanthanum ion adsorbent synthesized by surface ion imprinting technology has good specific recognition ability for lanthanum ions, achieves selective adsorption of lanthanum ions, and can be desorbed, regenerated and recycled.

[0025] As a further technical solution of the present invention, the aldehyde-modified molecular sieve is prepared by the following steps:

[0026] Aminated molecular sieves were added to glutaraldehyde aqueous solution and stirred at room temperature for 3 hours. The mixture was then filtered, and the filter cake was washed three times with deionized water and acetone, and dried at 90°C. The ratio of aminated molecular sieves to glutaraldehyde aqueous solution was 5-8 g: 50 mL, and the mass fraction of glutaraldehyde aqueous solution was 5%. The aminated molecular sieves were prepared by a method well known to those skilled in the art, namely, by using MCM-41 molecular sieves and silane coupling agents.

[0027] The beneficial effects of this invention are:

[0028] 1. To address the problem of high lanthanum oxide and cerium oxide content in current waste rare earth polishing powder, which leads to the waste of rare earth resources through direct landfilling, this invention provides a method for recycling polishing powder. First, utilizing the density difference between rare earth oxides and impurities, a gravity separation device is used to physically separate lighter impurities. Then, addressing the poor removal of silicon and aluminum impurities from current waste rare earth polishing powder, a step-by-step impurity removal process is adopted, involving hydrochloric acid treatment followed by sodium hydroxide treatment. Firstly, taking advantage of the different states of alumina and silicon dioxide in hydrochloric acid solution, alumina is first converted into water-soluble Al. 3+ The process yields primary waste powder and primary filtrate to be treated. Then, sodium hydroxide solution is used to treat the silica impurities in the primary waste powder, avoiding the introduction of hydrofluoric acid and efficiently removing silicon and aluminum impurities from the waste rare earth polishing powder.

[0029] 2. To address the loss of lanthanum oxide during the hydrochloric acid treatment of rare earth polishing powder (due to the reaction of lanthanum oxide with hydrochloric acid), this invention utilizes a lanthanum ion adsorbent to specifically enrich lanthanum ions in the primary filtrate. Through desorption, alkali treatment, precipitation, and calcination, lanthanum oxide is recovered, thereby reducing the loss of lanthanum oxide and preventing lanthanum ion pollution of water resources. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1

[0032] An amination molecular sieve is prepared by the following steps:

[0033] Weigh 1g of MCM-41 molecular sieve and place it in a three-necked flask containing 50mL of toluene. While stirring, add 0.5g of silane coupling agent KH-550 dropwise. Under nitrogen protection, heat to reflux and stir for 24h. After the reaction is complete, cool to room temperature, filter, wash and dry to obtain aminated molecular sieve.

[0034] Example 2

[0035] A lanthanum ion adsorbent is prepared by the following steps:

[0036] 0.4 g of polyacrylamide was added to 50 mL of deionized water and stirred at 25 °C for 3 h. Then, 0.5 g of lanthanum nitrate hexahydrate and 0.5 g of glutaraldehyde aqueous solution were added and stirred for 5 min. Then, 0.5 g of aldehyde-modified molecular sieve was added, and the mixture was heated to 50 °C and stirred for 5 h. After the reaction was complete, the mixture was filtered, and the filter cake was washed in 0.1 mol / L ethylenediaminetetraacetic acid solution for 24 h. This washing was repeated 4 times. The La content in the eluent was measured using FAAS (flame atomic absorption spectrometry). 3+ Concentration to ensure La 3+ The lanthanum ion adsorbent was completely removed, dried at 90°C to constant weight, and ground through an 80-100 mesh sieve to obtain a lanthanum ion adsorbent with a glutaraldehyde aqueous solution of 25% by mass.

[0037] The aldehyde-modified molecular sieve is prepared by the following steps:

[0038] Add 5g of the aminated molecular sieve from Example 1 to 50mL of 5wt% glutaraldehyde aqueous solution, stir and react at room temperature for 3h, filter, wash the filter cake three times with deionized water and acetone in sequence, and dry at 90℃.

[0039] Example 3

[0040] A lanthanum ion adsorbent is prepared by the following steps:

[0041] 0.5 g of polyacrylamide was added to 60 mL of deionized water and stirred at 25 °C for 3 h. Then, 0.5 g of lanthanum nitrate hexahydrate and 0.5 g of glutaraldehyde aqueous solution were added and stirred for 10 min. 1 g of aldehyde-modified molecular sieve was then added, and the mixture was heated to 50 °C and stirred for 6 h. After the reaction was completed, the mixture was filtered, and the filter cake was washed in 0.1 mol / L ethylenediaminetetraacetic acid solution for 24 h. This washing was repeated 4 times. The La content in the eluent was measured using FAAS (flame atomic absorption spectrometry). 3+ Concentration to ensure La 3+ The lanthanum ion adsorbent was completely removed, dried at 90°C to constant weight, and ground through an 80-100 mesh sieve to obtain a lanthanum ion adsorbent with a glutaraldehyde aqueous solution of 25% by mass.

[0042] The aldehyde-modified molecular sieve is prepared by the following steps:

[0043] Add 8g of the aminated molecular sieve from Example 1 to 50mL of 5wt% glutaraldehyde aqueous solution, stir and react at room temperature for 3h, filter, wash the filter cake three times with deionized water and acetone in sequence, and dry at 90℃.

[0044] Example 4

[0045] A method for recycling polishing powder includes the following steps:

[0046] Step S1: Pass the waste rare earth polishing powder through a 60-mesh sieve, then prepare a slurry with a concentration of 25% by mass. Use a shaking table gravity separation device for gravity separation. The heavy components obtained after separation are dried to obtain gravity-separated rare earth polishing powder.

[0047] Step S2: Place the heavy-selection rare earth polishing powder in a reaction vessel, add a 1 mol / L hydrochloric acid solution, control the temperature at 20℃, stir and react for 1 hour. After the reaction is completed, filter the powder using a vacuum filter, wash the filter cake with deionized water until the washing liquid is neutral, dry it at 100℃ to constant weight, collect the filtrate for later use, and obtain primary waste powder and primary filtrate to be treated. The mass ratio of heavy-selection rare earth polishing powder to hydrochloric acid solution is 0.5:1.

[0048] Step S3: Add the lanthanum ion adsorbent of Example 3 to the primary filtrate to be treated, stir for 4 hours, centrifuge and filter, discharge the filtrate, wash the precipitate three times with deionized water, transfer it to a 0.1 mol / L ethylenediaminetetraacetic acid solution for desorption for 24 hours, filter, collect the filtrate for later use, and obtain recyclable lanthanum ion adsorbent (filter cake) and secondary filtrate to be treated. The ratio of the amount of primary filtrate to lanthanum ion adsorbent is 30 mL: 10 mg.

[0049] Step S4: Add 25wt% ammonia to the secondary filtrate to adjust the pH to 8, stir evenly to form a precursor solution, control the temperature at 50℃, stir for 8 hours, cool to room temperature, filter to obtain precipitate, wash the precipitate with deionized water, dry at 80℃, and then calcine at 500℃ for 8 hours to obtain recovered lanthanum oxide.

[0050] Step S5: Place the primary waste powder in a reaction vessel, add a 2.5 mol / L sodium hydroxide solution, control the temperature at 105℃, stir and react for 1 hour. After the reaction is complete, cool to room temperature, filter with a vacuum filter, wash the filter cake with deionized water until the washing liquid is neutral, and dry at 100℃ to constant weight to obtain recovered cerium oxide. The mass ratio of sodium hydroxide solution to primary waste powder is 2:1.

[0051] Step S6: Mix the recovered lanthanum oxide obtained in step S4 and the recovered cerium oxide obtained in step S5, calcine at 1000°C for 6 hours, and then pulverize by airflow after cooling.

[0052] Example 5

[0053] A method for recycling polishing powder includes the following steps:

[0054] Step S1: Pass the waste rare earth polishing powder through a 60-mesh sieve, then prepare a slurry with a concentration of 30% by mass. Use a shaking table gravity separation device for gravity separation. The heavy components obtained after separation are dried to obtain gravity-separated rare earth polishing powder.

[0055] Step S2: Place the heavy-selection rare earth polishing powder in a reaction vessel, add a 1 mol / L hydrochloric acid solution, control the temperature at 22℃, stir and react for 1.3 h. After the reaction is complete, filter with a vacuum filter, wash the filter cake with deionized water until the washing liquid is neutral, dry at 100℃ to constant weight, collect the filtrate for later use, and obtain primary waste powder and primary filtrate to be treated. The mass ratio of heavy-selection rare earth polishing powder to hydrochloric acid solution is 0.5:1.

[0056] Step S3: Add the lanthanum ion adsorbent of Example 3 to the primary filtrate to be treated, stir for 5 hours, centrifuge and filter, discharge the filtrate, wash the precipitate 4 times with deionized water, transfer it to a 0.1 mol / L ethylenediaminetetraacetic acid solution for desorption for 24 hours, filter, collect the filtrate for later use, and obtain recyclable lanthanum ion adsorbent (filter cake) and secondary filtrate to be treated. The ratio of primary filtrate to lanthanum ion adsorbent is 40 mL: 10 mg.

[0057] Step S4: Add 27wt% ammonia to the secondary filtrate to adjust the pH to 10, stir evenly to form a precursor solution, control the temperature at 70℃, stir for 9 hours, cool to room temperature, filter to obtain precipitate, wash the precipitate with deionized water, dry at 85℃, and then calcine at 550℃ for 6 hours to obtain recovered lanthanum oxide.

[0058] Step S5: Place the primary waste powder in a reaction vessel, add a 2.5 mol / L sodium hydroxide solution, control the temperature at 105℃, stir and react for 1.2 h. After the reaction is complete, cool to room temperature, filter with a vacuum filter, wash the filter cake with deionized water until the washing liquid is neutral, and dry at 100℃ to constant weight to obtain recovered cerium oxide. The mass ratio of sodium hydroxide solution to primary waste powder is 2:1.

[0059] Step S6: Mix the recovered lanthanum oxide obtained in step S4 and the recovered cerium oxide obtained in step S5, calcine at 1000°C for 4 hours, and then pulverize by airflow after cooling.

[0060] Example 6

[0061] A method for recycling polishing powder includes the following steps:

[0062] Step S1: Pass the waste rare earth polishing powder through a 60-mesh sieve, then prepare a slurry with a concentration of 35% by mass. Use a shaking table gravity separation device for gravity separation. The heavy components obtained after separation are dried to obtain gravity-separated rare earth polishing powder.

[0063] Step S2: Place the heavy-selection rare earth polishing powder in a reaction vessel, add a 1 mol / L hydrochloric acid solution, control the temperature at 25℃, stir and react for 1.5 h. After the reaction is completed, filter with a vacuum filter, wash the filter cake with deionized water until the washing liquid is neutral, dry at 100℃ to constant weight, collect the filtrate for later use, and obtain primary waste powder and primary filtrate to be treated. The mass ratio of heavy-selection rare earth polishing powder to hydrochloric acid solution is 0.5:1.

[0064] Step S3: Add the lanthanum ion adsorbent of Example 2 to the primary filtrate to be treated, stir for 6 hours, centrifuge and filter, wash the precipitate 5 times with deionized water, transfer it to a 0.1 mol / L ethylenediaminetetraacetic acid solution for desorption for 24 hours, filter, collect the filtrate for later use, and obtain recyclable lanthanum ion adsorbent (filter cake) and secondary filtrate to be treated. The ratio of primary filtrate to lanthanum ion adsorbent is 50 mL: 10 mg.

[0065] Step S4: Add 28wt% ammonia to the secondary filtrate to adjust the pH to 12, stir evenly to form a precursor solution, control the temperature at 120℃, stir and react for 10h, cool to room temperature, filter to obtain precipitate, wash the precipitate with deionized water, dry at 90℃ and then calcine at 600℃ for 8h to obtain recovered lanthanum oxide.

[0066] Step S5: Place the primary waste powder in a reaction vessel, add a 2.5 mol / L sodium hydroxide solution, control the temperature at 105℃, stir and react for 1.5 h. After the reaction is complete, cool to room temperature, filter with a vacuum filter, wash the filter cake with deionized water until the washing liquid is neutral, and dry at 100℃ to constant weight to obtain recovered cerium oxide. The mass ratio of sodium hydroxide solution to primary waste powder is 2:1.

[0067] Step S6: Mix the recovered lanthanum oxide obtained in step S4 and the recovered cerium oxide obtained in step S5, calcine at 1000°C for 6 hours, and then pulverize by airflow after cooling.

[0068] Comparative Example 1

[0069] A method for recycling polishing powder includes the following steps:

[0070] Step S1: Pass the waste rare earth polishing powder through a 60-mesh sieve, then prepare a slurry with a concentration of 25-35% by mass. Use a shaking table gravity separation device for gravity separation. The heavy components obtained after separation are dried to obtain gravity-separated rare earth polishing powder.

[0071] Step S2: Place the heavy-selection rare earth polishing powder in a reaction vessel, add a 1 mol / L hydrochloric acid solution, control the temperature at 20-25℃, stir and react for 1-1.5 h. After the reaction is complete, filter the powder using a vacuum filter, wash the filter cake with deionized water until the washing liquid is neutral, dry it at 100℃ to constant weight, collect the filtrate for later use, and obtain primary waste powder and primary filtrate to be treated. The mass ratio of heavy-selection rare earth polishing powder to hydrochloric acid solution is 0.5:1, and the concentration of hydrochloric acid solution is 1 mol / L.

[0072] Step S3: Place the primary waste powder in a reaction vessel, add sodium hydroxide solution, control the temperature at 105℃, stir and react for 1-1.5 hours. After the reaction is complete, cool to room temperature, filter using a vacuum filter, wash the filter cake with deionized water until the washing liquid is neutral, and dry at 100℃ to constant weight. The mass ratio of sodium hydroxide solution to primary waste powder is 2:1, and the concentration of sodium hydroxide solution is 2.5 mol / L.

[0073] Waste rare earth polishing powder from a company in Zhuzhou, Hunan Province, was crushed, sieved through a 120-mesh sieve, and analyzed by XRF. The composition was found to be 43.36% CeO2, 19.07% La3O2, 18.52% Al2O3, 7.68% SiO2, and 1.77% CaO. The waste rare earth polishing powder was recycled using the methods described in Examples 4-6 and Comparative Example 1. The rare earth oxide recovery rate was tested. The rare earth oxide recovery rate was calculated as (mass of recovered product) / (mass of CeO2 and La3O2 in the waste rare earth polishing powder) × 100%. The contents of CeO2, La3O2, Al2O3, and SiO2 in the recovered product were also measured. The results are shown in Table 1.

[0074] Table 1

[0075] project Example 4 Example 5 Example 6 Comparative Example 1 Recovery rate (%) 97.9 98.0 98.2 85.2 <![CDATA[CeO2 content (%)]]> 67.1 67.3 68.2 48.2 <![CDATA[La3O2 content (%)]]> 28.2 28.4 30.1 22.1 <![CDATA[Al2O3 content (%)]]> 0.59 0.56 0.42 2.4 <![CDATA[SiO2 content (%)]]> 0.96 0.93 0.89 3.7

[0076] As can be seen from Table 1, compared with the polishing powder recovery method in Comparative Example 1, the polishing powder recovery methods in Examples 4, 5, and 6 have a higher rare earth oxide recovery rate and a lower impurity content.

[0077] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0078] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for recycling polishing powder, characterized by, Comprise the following steps: Step S1, the waste rare earth polishing powder is passed through 60 mesh sieve, the pulp is adjusted, and the shaking table gravity separation equipment is used for gravity separation to obtain the gravity separation rare earth polishing powder; Step S2, the gravity separation rare earth polishing powder is placed in hydrochloric acid solution, stirred and reacted at 20-25 DEG C for 1-1.5 h, suction filtered, the filter cake is washed and dried, the filtrate is collected for standby, the first grade treatment waste powder and the first grade treatment filtrate are obtained; Step S3, lanthanum ion adsorbent is added to the first grade treatment filtrate, after stirring for 4-6 h, centrifugal filtration is carried out, the precipitate is washed and transferred to ethylenediaminetetraacetic acid solution for desorption for 24 h, filtration is carried out, and the filtrate is the second grade treatment filtrate; Step S4, ammonia water is added to the second grade treatment filtrate to adjust the pH to 8-12, after stirring uniformly, after stirring and reacting at 50-120 DEG C for 8-10 h, cooling to room temperature, filtration is carried out to obtain the precipitate, the precipitate is washed, dried, and calcined at 500-600 DEG C for 2-8 h to obtain the recovered lanthanum oxide; Step S5, the first grade treatment waste powder is placed in sodium hydroxide solution, stirred and reacted at 105 DEG C for 1-1.5 h, after cooling, vacuum suction filtration is carried out, the filter cake is washed and dried to obtain the recovered cerium oxide; Step S6, the recovered lanthanum oxide obtained in step S4 and the recovered cerium oxide obtained in step S5 are mixed, calcined at 1000-1100 DEG C for 3-6 h, and after cooling, air flow crushing is carried out; The lanthanum ion adsorbent is prepared by the following steps: Polyacrylamide is added to deionized water, stirred at 25 DEG C for 3 h, then lanthanum nitrate hexahydrate and glutaraldehyde aqueous solution are added, after stirring for 5-10 min, aldehyde group molecular sieve is added, the temperature is raised to 50 DEG C, and stirring is carried out for 5-6 h, after the reaction is completed, filtration is carried out, the filter cake is washed in 0.1 mol / L ethylenediaminetetraacetic acid solution for 24 h, washed, dried, ground to obtain the lanthanum ion adsorbent; The content of CeO2 in the waste rare earth polishing powder is 43.36%, the content of La3O2 is 19.07%, the content of Al2O3 is 18.52%, the content of SiO2 is 7.68%, and the content of CaO is 1.77%.

2. The method of claim 1, wherein the polishing powder is recovered by the steps of: The concentration of the pulp in step S1 is 25-35% by mass percentage.

3. The method of claim 1, wherein the polishing powder is a cerium oxide polishing powder. In step S2, the mass ratio of the gravity separation rare earth polishing powder and the hydrochloric acid solution is 0.5:1, and the concentration of the hydrochloric acid solution is 1 mol / L.

4. The method of claim 1, wherein the polishing powder is a cerium oxide polishing powder. In step S3, the dosage ratio of the first grade treatment filtrate and the lanthanum ion adsorbent is 30-50 mL:10 mg, and the concentration of the ethylenediaminetetraacetic acid solution is 0.1 mol / L.

5. The method of claim 1, wherein the polishing powder is a cerium oxide polishing powder. In step S4, the mass fraction of the ammonia water is 25-28%.

6. The method of claim 1, wherein the polishing powder is a cerium oxide polishing powder. In step S5, the mass ratio of the sodium hydroxide solution and the first grade treatment waste powder is 2:1, and the concentration of the sodium hydroxide solution is 2.5 mol / L.

7. The method of claim 1, wherein the polishing powder is a cerium oxide polishing powder. The dosage ratio of polyacrylamide, deionized water, lanthanum nitrate hexahydrate, glutaraldehyde aqueous solution and aldehyde group molecular sieve is 0.4-0.5 g:50-60 mL:0.5 g:0.5 g:0.5-1 g, and the mass fraction of the glutaraldehyde aqueous solution is 25%.

8. The method of claim 1, wherein the polishing powder is a cerium oxide polishing powder. The aldehyde group molecular sieve is prepared by the following steps: The amino-functionalized molecular sieve is added into the aqueous glutaraldehyde solution, and the reaction is stirred at room temperature for 3h, and then filtered, and the filter cake is washed with deionized water and acetone for three times, and dried at 90 DEG C, wherein the ratio of the amino-functionalized molecular sieve to the aqueous glutaraldehyde solution is 5-8g:50mL, and the mass fraction of the aqueous glutaraldehyde solution is 5%.