Method for selectively separating and purifying rare earth cerium in waste polishing powder pickle liquor
Through the combined method of double salt precipitation, strong alkali conversion and mixed extractants, the problem of selective separation and purification of rare earth copper in waste polishing powder acid leaching solution was solved, and efficient and environmentally friendly rare earth cerium separation and purification effects were achieved.
Patent Information
- Application Number
- CN202510654929.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-21
- Publication Date
- 2025-09-19
AI Technical Summary
Existing technologies make it difficult to efficiently and selectively separate and purify rare earth cerium from waste polishing powder acid leaching solutions, and traditional methods are complex, energy-intensive, and cause serious environmental pollution.
The method adopts double salt precipitation, strong alkali conversion and low acid dissolution combined with a mixed extractant of n-octyl phosphoric acid, tributyl phosphate and kerosene. Impurities are removed by double salt precipitation, aluminum and calcium elements are separated by strong alkali conversion, and rare earth chloride solution is obtained by low acid dissolution. The mixed extractant is then used for selective extraction and back extraction to obtain a high-purity cerium sulfate solution.
The selective and precise separation of rare earth cerium is achieved, the extraction rate and purification rate are improved, environmental pollution is reduced, the operation process is simplified, and the cost is reduced.
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Figure CN120666201A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of deep purification and recovery of valuable components in solid waste, in particular to a method for selectively separating and purifying rare earth cerium in waste polishing powder acid leaching solution. Background Art
[0002] With the increasing importance of rare earth resources in high-tech industries, energy, environmental protection, and the military, waste polishing powder has attracted widespread attention as a potential source of rare earth elements (REEs). Waste polishing powder contains a large number of rare earth elements, particularly lanthanides such as lanthanum and cerium. To achieve sustainable utilization and development of rare earth resources, recovering REEs from waste polishing powder not only reduces resource waste but also alleviates the environmental pressures associated with rare earth mining. Therefore, efficient and highly selective extraction, separation, and purification of REEs from waste polishing powder have become key research areas. The acid leaching process for REEs in waste polishing powder is often accompanied by a large number of impurity ions, which pose challenges to their separation and purification. Furthermore, lanthanum and cerium are two common REEs in the leaching solution of waste polishing powder. However, due to their similar chemical properties and electronic structures, the selective separation of lanthanum and cerium has been a technical challenge in the extraction and recovery of REEs from waste polishing powder leaching solutions. Traditional REE purification methods, such as ion exchange and precipitation, often suffer from poor reaction selectivity, unsatisfactory separation results, and complex operations.
[0003] Prior art patents disclose a method for separating and purifying a single heavy rare earth element using a full extraction process. This method involves first purifying non-rare earth impurities with N235, followed by saponification with a dual extraction system of P507 and C272, followed by full extraction, separation, and purification. Another patent discloses a method for recovering waste rare earth polishing powder. This method involves using a strong acid multi-stage countercurrent leaching process to produce a leachate containing rare earth ions. This leachate containing rare earth ions is then subjected to a two-stage extraction using a combination of saponified 2-ethylhexyl phosphate and sulfonated kerosene, followed by stripping to produce a high-purity rare earth chloride solution. This method is not only complex and consumes a lot of chemical reagents, but also requires a special multi-stage countercurrent leaching unit, resulting in high water and energy recovery costs. Furthermore, it is not effective for the selective separation and purification of single lanthanide elements. Therefore, it is of great strategic significance to find a method for recovering rare earth elements from waste polishing powder acid leachate that has high rare earth element separation efficiency, good single rare earth selectivity, and minimal environmental pollution.
[0004] Therefore, how to provide a method for selective separation and purification of rare earth cerium in waste polishing powder acid leaching solution, so that it can achieve the technical effect of selective and deep separation of rare earth cerium in waste polishing powder acid leaching solution and improve the extraction rate and purification rate of rare earth cerium, is a technical problem that technical personnel in this field urgently need to solve. Summary of the Invention
[0005] In view of the problems existing in the prior art, the technical problem to be solved by the present invention is to provide a method for selectively separating and purifying rare earth cerium in the acid leaching solution of waste polishing powder, so that it can achieve the technical effect of selectively and deeply separating rare earth cerium in the acid leaching solution of waste polishing powder and improving the extraction rate and purification rate of rare earth cerium.
[0006] To achieve the above-mentioned objectives, the present invention provides a method for selectively separating and purifying rare earth cerium from waste polishing powder acid leachate. The method for selectively separating and purifying rare earth cerium from waste polishing powder acid leachate comprises: primary purification: subjecting the waste polishing powder acid leachate to double salt precipitation, strong base conversion, and low acid dissolution in sequence to obtain a rare earth chloride salt solution; extraction separation: adjusting the pH value of the obtained rare earth chloride salt solution with ammonia water, then mixing it with a mixed extractant, shaking it, and separating the liquids to obtain a first extract phase and a first raffinate phase; back extraction: mixing the obtained first extract phase with a sulfuric acid aqueous solution, shaking it, and separating the liquids to obtain a second extract phase and a high-purity cerium sulfate solution; the mixed extractant is a mixture of n-octyl phosphoric acid, tributyl phosphate, and kerosene.
[0007] In the first aspect, the step of subjecting the waste polishing powder acid leaching solution to double salt precipitation, strong alkali conversion, and low acid dissolution to obtain a rare earth chloride salt solution specifically comprises: mixing the waste polishing powder acid leaching solution with sodium sulfate, performing a double salt precipitation reaction under heating and stirring conditions, performing solid-liquid separation after the reaction to obtain a first filter residue and a first filtrate, adding a sodium hydroxide aqueous solution to the first filter residue for reaction, and performing solid-liquid separation after the reaction to obtain a second filter residue and a second filtrate; and adding dilute hydrochloric acid to the second filter residue for reaction to obtain a rare earth chloride salt solution.
[0008] In the first aspect, the solid-liquid ratio of the sodium sulfate to the waste polishing powder acid leaching solution is 100g / L to 200g / L; the reaction temperature of the double salt precipitation reaction is 60°C to 100°C, and the reaction time of the double salt precipitation reaction is 10min to 90min.
[0009] In the first aspect, during the primary purification process, the amount of the dilute hydrochloric acid and the amount of the sodium hydroxide aqueous solution added are both excessive, the molar concentration of the dilute hydrochloric acid is 0.1 mol / L to 1 mol / L, and the mass concentration of the sodium hydroxide aqueous solution is 30% to 50%.
[0010] In the first aspect, the ammonia water adjusts the pH value of the rare earth chloride salt solution to 1.6-2; the volume ratio of the rare earth chloride salt solution to the mixed extractant is 3:1-1:3.
[0011] In the first aspect, in the extraction separation, the shaking time is 5 min to 20 min, and the shaking speed is 50 rpm to 300 rpm.
[0012] In the first aspect, the volume ratio of the first extraction phase to the aqueous sulfuric acid solution is 3:1 to 1:3, and the molar concentration of the aqueous sulfuric acid solution is 0.5 mol / L to 6 mol / L.
[0013] In the first aspect, in the stripping, the shaking time is 2 min to 15 min, and the shaking speed is 50 rpm to 300 rpm.
[0014] In a first aspect, the method for preparing the mixture of n-octyl phosphoric acid, tributyl phosphate, and kerosene comprises: uniformly mixing tributyl phosphate and kerosene, then adding n-octyl phosphoric acid to dissolve the mixture, thereby obtaining the mixture of n-octyl phosphoric acid, tributyl phosphate, and kerosene; wherein the sum of the volume ratios of the tributyl phosphate and the kerosene is 100%, and the volume ratio of the tributyl phosphate to the kerosene is 10-30:70-90; and the concentration of the n-octyl phosphoric acid in the mixture of n-octyl phosphoric acid, tributyl phosphate, and kerosene is 0.005 mol / L to 0.02 mol / L.
[0015] Beneficial effects:
[0016] Due to the adoption of the above technical scheme, the present invention has the following advantages compared with the prior art: 1) The method of the present invention for selectively separating and purifying rare earth cerium from waste polishing powder acid leaching solution, wherein the rare earth elements in the waste polishing powder acid leaching solution are precipitated by a double salt precipitation method. During the double salt precipitation process, the aluminum and calcium elements in the waste polishing powder acid leaching solution are also precipitated, thereby obtaining a first filter residue containing rare earth elements such as cerium and lanthanum, as well as aluminum and calcium elements. The first filter residue is then subjected to strong alkali conversion to convert the aluminum element and part of the calcium element precipitated in the first filter residue into soluble compounds, thereby separating the rare earth elements such as cerium and lanthanum from the aluminum element and part of the calcium element, thereby obtaining a second filter residue enriched with a large amount of rare earth elements such as cerium and lanthanum. The invention relates to a second filter residue; an excess of dilute hydrochloric acid is added to the second filter residue to dissolve the precipitate containing rare earth elements such as cerium and lanthanum in the second filter residue to obtain a rare earth chloride solution containing rare earth elements such as cerium and lanthanum, which is convenient for subsequent extraction; the rare earth chloride solution mainly contains rare earth elements such as cerium and lanthanum, and a mixed extractant is used to selectively extract the cerium in the rare earth chloride solution to obtain a first extraction phase and a first raffinate phase, the extraction rate of cerium in the first extraction phase is more than 60%, the extraction rate of lanthanum does not exceed 2%, and the cerium has a good selective extraction effect; an aqueous sulfuric acid solution is added to the first extraction phase for back extraction to transfer the cerium from the organic phase back to the aqueous phase, and further extract the cerium. Purification is carried out to obtain a high-purity cerium sulfate solution, and the purity of cerium sulfate in the high-purity cerium sulfate solution can reach 99.9%; From the above, it can be seen that the method for selective separation and purification of rare earth cerium in waste polishing powder acid leaching solution of the present invention combines double salt precipitation technology with extraction and stripping, effectively removes impurity elements, and selectively separates cerium in depth, thereby improving the selective recovery efficiency of a single cerium element in the waste polishing powder acid leaching solution and ensuring the selective deep purification of a single cerium element; 2) the method for selective separation and purification of rare earth cerium in waste polishing powder acid leaching solution of the present invention adopts a mixed extractant of n-octyl phosphoric acid, tributyl phosphate and kerosene, wherein the sum of the volume ratios of the tributyl phosphate and the kerosene is 100%, and the The volume ratio of tributyl phosphate to the kerosene is 10-30:70-90; the concentration of n-octyl phosphoric acid in the mixture of n-octyl phosphoric acid, tributyl phosphate and kerosene is 0.005 mol / L-0.02 mol / L, and tributyl phosphate not only has an extraction effect but also dissolves n-octyl phosphoric acid. Through the combination of n-octyl phosphoric acid and tributyl phosphate, the mixed extractant can achieve the technical effect of selectively extracting a single cerium element; 3) The method for selectively separating and purifying rare earth cerium in a waste polishing powder acid leaching solution of the present invention has a good extraction effect under low pH conditions, does not require a complex and highly polluting saponification process, and has the advantages of short phase separation time, simple operation, and low environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0018] Figure 1 The present invention is a process flow chart of a method for selectively separating and purifying rare earth cerium from waste polishing powder acid leaching solution. DETAILED DESCRIPTION
[0019] The following will be combined with the drawings in the embodiments of this specification to clearly and completely describe the technical solutions in the embodiments of this specification. Obviously, the embodiments described are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of this invention.
[0020] Example 1
[0021] like Figure 1 As shown, this embodiment 1 provides a method for selectively separating and purifying rare earth cerium in a waste polishing powder acid leachate, and the method for selectively separating and purifying rare earth cerium in a waste polishing powder acid leachate includes: primary purification: subjecting the waste polishing powder acid leachate to double salt precipitation, strong base conversion, and low acid dissolution in sequence to obtain a rare earth chloride solution; extraction separation: adjusting the pH value of the obtained rare earth chloride solution by ammonia water, and then mixing it with a mixed extractant, shaking it, and separating the liquids to obtain a first extract phase and a first raffinate phase; back extraction: mixing the obtained first extract phase with a sulfuric acid aqueous solution, shaking it, and separating the liquids to obtain a second extract phase and a high-purity cerium sulfate solution; the mixed extractant is a mixture of n-octyl phosphoric acid, tributyl phosphate, and kerosene.
[0022] Compared with the prior art, the method for selectively separating and purifying rare earth cerium from waste polishing powder acid leaching solution provided in Example 1 of the present invention has the following advantages:
[0023] 1. A method for selectively separating and purifying rare earth cerium from waste polishing powder acid leaching liquid of the present invention comprises the following steps: precipitating rare earth elements in the waste polishing powder acid leaching liquid by a double salt precipitation method; during the double salt precipitation process, aluminum and calcium elements in the waste polishing powder acid leaching liquid are also precipitated, thereby obtaining a first filter residue containing rare earth elements such as cerium and lanthanum, as well as aluminum and calcium elements; then subjecting the first filter residue to strong alkali conversion to convert the aluminum element and part of the calcium element precipitated in the first filter residue into soluble compounds, thereby separating the rare earth elements such as cerium and lanthanum from the aluminum element and part of the calcium element, thereby obtaining a second filter residue enriched in a large amount of rare earth elements such as cerium and lanthanum; adding excess dilute hydrochloric acid to the second filter residue to dissolve the precipitate containing rare earth elements such as cerium and lanthanum in the second filter residue, thereby obtaining a rare earth chloride solution containing rare earth elements such as cerium and lanthanum, which is convenient for subsequent extraction; the rare earth chloride solution mainly contains cerium. The invention discloses a method for selectively separating and purifying rare earth cerium from a rare earth chloride solution containing lanthanum, cerium and other rare earth elements, and adopts a mixed extractant to selectively extract cerium from a rare earth chloride solution to obtain a first extraction phase and a first raffinate phase. The extraction rate of cerium in the first extraction phase is above 60%, and the extraction rate of lanthanum does not exceed 2%, which has a good selective extraction effect on cerium. A sulfuric acid aqueous solution is added to the first extraction phase for back extraction to transfer the cerium from the organic phase back to the aqueous phase, and the cerium is further purified to obtain a high-purity cerium sulfate solution. The purity of cerium sulfate in the high-purity cerium sulfate solution can reach 99.9%. As can be seen from the above, the method for selective separation and purification of rare earth cerium in a waste polishing powder acid leaching solution of the present invention combines complex salt precipitation technology with extraction and back extraction to effectively remove impurity elements, selectively and deeply separate cerium, improve the selective recovery efficiency of a single cerium element in the waste polishing powder acid leaching solution, and ensure the selective deep purification of a single cerium element.
[0024] 2. The present invention provides a method for selectively separating and purifying rare earth cerium from an acid leaching solution of waste polishing powder, wherein the mixed extractant used is a mixture of n-octyl phosphoric acid, tributyl phosphate, and kerosene, wherein the sum of the volume ratios of the tributyl phosphate and the kerosene is 100%, and the volume ratio of the tributyl phosphate to the kerosene is 10-30:70-90; the concentration of the n-octyl phosphoric acid in the mixture of n-octyl phosphoric acid, tributyl phosphate, and kerosene is 0.005 mol / L to 0.02 mol / L, and the tributyl phosphate not only has an extraction effect but also dissolves the n-octyl phosphoric acid. Through the combination of n-octyl phosphoric acid and tributyl phosphate, the mixed extractant can achieve the technical effect of selectively extracting a single cerium element.
[0025] 3. The method of selectively separating and purifying rare earth cerium from waste polishing powder acid leaching solution of the present invention has a good extraction effect under low pH conditions, does not require a complex and polluting saponification process, and has the advantages of short phase separation time, simple operation, and low environmental pollution.
[0026] In some possible implementations, the step of subjecting the waste polishing powder acid leaching solution to double salt precipitation, strong alkali conversion, and low acid dissolution to obtain a rare earth chloride solution specifically includes: mixing the waste polishing powder acid leaching solution with sodium sulfate, conducting a double salt precipitation reaction under heating and stirring conditions, performing solid-liquid separation after the reaction to obtain a first filter residue and a first filtrate, adding a sodium hydroxide aqueous solution to the first filter residue for reaction, and performing solid-liquid separation after the reaction to obtain a second filter residue and a second filtrate; adding dilute hydrochloric acid to the second filter residue for reaction to obtain a rare earth chloride solution; the solid-liquid ratio of the sodium sulfate to the waste polishing powder acid leaching solution is 100 g / L to 200 g / L; the reaction temperature of the double salt precipitation reaction is 60° C. to 100° C., and the reaction time of the double salt precipitation reaction is 10 min to 90 min; during the initial purification process, the amount of the dilute hydrochloric acid and the amount of the sodium hydroxide aqueous solution added are both excessive, the molar concentration of the dilute hydrochloric acid is 0.1 mol / L to 1 mol / L, and the mass concentration of the sodium hydroxide aqueous solution is 30% to 50%.
[0027] Specifically, double salt precipitation is mainly used to precipitate rare earth elements such as cerium and lanthanum; excess sodium hydroxide aqueous solution is mainly used to convert non-rare earth elements in the double salt precipitation residue into soluble compounds and remove impurities of non-rare earth elements so as to separate non-rare earth elements from rare earth elements such as cerium and lanthanum; excess dilute hydrochloric acid is mainly used to dissolve the hydroxide precipitates of rare earth elements such as cerium and lanthanum to obtain a rare earth chloride salt solution, which is convenient for the subsequent extraction of cerium.
[0028] In some possible implementations, the ammonia water adjusts the pH value of the rare earth chloride salt solution to 1.6-2; the volume ratio of the rare earth chloride salt solution to the mixed extractant is 3:1-1:3; during the extraction separation, the oscillation time is 5 min-20 min, and the oscillation speed is 50 rpm-300 rpm.
[0029] Specifically, the pH value of the acid hydrolyzate is adjusted to 1.6-2.0 by using ammonia water to improve the extraction effect and reduce the extraction phase separation time.
[0030] In some possible implementations, the volume ratio of the first extraction phase to the aqueous sulfuric acid solution is 3:1 to 1:3, and the molar concentration of the aqueous sulfuric acid solution is 0.5 mol / L to 6 mol / L; in the stripping, the oscillation time is 2 min to 15 min, and the oscillation speed is 50 rpm to 300 rpm.
[0031] Specifically, the back extraction is mainly used to further purify the cerium element in the first extraction phase.
[0032] In some possible implementations, the method for preparing the mixture of n-octyl phosphoric acid, tributyl phosphate, and kerosene includes: uniformly mixing tributyl phosphate and kerosene, then adding n-octyl phosphoric acid to dissolve, to obtain a mixture of n-octyl phosphoric acid, tributyl phosphate, and kerosene; the sum of the volume ratios of the tributyl phosphate and the kerosene is 100%, and the volume ratio of the tributyl phosphate to the kerosene is 10-30:70-90; and the concentration of the n-octyl phosphoric acid in the mixture of n-octyl phosphoric acid, tributyl phosphate, and kerosene is 0.005 mol / L to 0.02 mol / L.
[0033] Specifically, in the present invention, tributyl phosphate is used not only as an extractant but also as a solvent for n-octyl phosphoric acid. Through the combination of n-octyl phosphoric acid and tributyl phosphate, the mixed extractant has a selective extraction and recovery effect on a single cerium element.
[0034] In order to further illustrate the technical solution of the present application in detail to support the technical problem to be solved by the present application, the preparation method is specifically illustrated below, as shown in Examples 1 to 4 and Comparative Examples 1 to 2.
[0035] Example 1
[0036] A method for selectively separating and purifying rare earth cerium from waste polishing powder acid leaching solution, specifically comprising:
[0037] Primary purification: mixing the waste polishing powder acid leaching solution with sodium sulfate, reacting the mixture under heating and stirring at 95° C. for 30 minutes, performing solid-liquid separation after the reaction to obtain a first filter residue and a first filtrate, adding an excess of a 50% sodium hydroxide aqueous solution to the first filter residue for reaction, and performing solid-liquid separation after the reaction to obtain a second filter residue and a second filtrate; adding an excess of 0.5 mol / L dilute hydrochloric acid to the second filter residue for reaction to obtain a rare earth chloride solution; the solid-liquid ratio of the sodium sulfate to the waste polishing powder acid leaching solution is 200 g / L;
[0038] Extraction and separation: The rare earth chloride solution obtained is adjusted to a pH of 1.77 with ammonia water, then mixed with a mixed extractant, and shaken at a shaking speed of 200 rpm for 10 minutes before separation to obtain a first extract phase and a first raffinate phase; the volume ratio of the rare earth chloride solution to the mixed extractant is 1:1; the preparation method of the mixed extractant specifically comprises: uniformly mixing tributyl phosphate and kerosene at a volume ratio of 24.5:75.5, then adding n-octyl phosphoric acid to dissolve, to obtain a mixture of n-octyl phosphoric acid, tributyl phosphate, and kerosene; the concentration of n-octyl phosphoric acid in the mixture of n-octyl phosphoric acid, tributyl phosphate, and kerosene is 0.01 mol / L;
[0039] Stripping: The obtained first extract phase is mixed with an aqueous sulfuric acid solution, shaken at an oscillation speed of 200 rpm for 10 minutes, and then separated to obtain a second extract phase and a high-purity cerium sulfate solution; the volume ratio of the first extract phase to the aqueous sulfuric acid solution is 1:1, and the molar concentration of the aqueous sulfuric acid solution is 4 mol / L.
[0040] Example 2
[0041] A method for selectively separating and purifying rare earth cerium from waste polishing powder acid leaching solution, specifically comprising:
[0042] Primary purification: mixing the waste polishing powder acid leaching solution with sodium sulfate, reacting the mixture under heating and stirring at 95° C. for 30 minutes, performing solid-liquid separation after the reaction to obtain a first filter residue and a first filtrate, adding an excess of a 50% sodium hydroxide aqueous solution to the first filter residue for reaction, and performing solid-liquid separation after the reaction to obtain a second filter residue and a second filtrate; adding an excess of 0.5 mol / L dilute hydrochloric acid to the second filter residue for reaction to obtain a rare earth chloride solution; the solid-liquid ratio of the sodium sulfate to the waste polishing powder acid leaching solution is 200 g / L;
[0043] Extraction and separation: The rare earth chloride solution obtained is adjusted to a pH of 1.79 with aqueous ammonia, then mixed with a mixed extractant, and shaken at a shaking speed of 200 rpm for 9 minutes before separation to obtain a first extract phase and a first raffinate phase; the volume ratio of the rare earth chloride solution to the mixed extractant is 1:1; the preparation method of the mixed extractant specifically comprises: uniformly mixing tributyl phosphate and kerosene at a volume ratio of 25:75, then adding n-octyl phosphoric acid to dissolve, to obtain a mixture of n-octyl phosphoric acid, tributyl phosphate, and kerosene; the concentration of n-octyl phosphoric acid in the mixture of n-octyl phosphoric acid, tributyl phosphate, and kerosene is 0.01 mol / L;
[0044] Stripping: The obtained first extract phase is mixed with an aqueous sulfuric acid solution, shaken at an oscillation speed of 200 rpm for 10 minutes, and then separated to obtain a second extract phase and a high-purity cerium sulfate solution; the volume ratio of the first extract phase to the aqueous sulfuric acid solution is 1:1, and the molar concentration of the aqueous sulfuric acid solution is 4 mol / L.
[0045] Example 3
[0046] A method for selectively separating and purifying rare earth cerium from waste polishing powder acid leaching solution, specifically comprising:
[0047] Primary purification: mixing the waste polishing powder acid leaching solution with sodium sulfate, reacting the mixture under heating and stirring at 95° C. for 30 minutes, performing solid-liquid separation after the reaction to obtain a first filter residue and a first filtrate, adding an excess of a 50% sodium hydroxide aqueous solution to the first filter residue for reaction, and performing solid-liquid separation after the reaction to obtain a second filter residue and a second filtrate; adding an excess of 0.5 mol / L dilute hydrochloric acid to the second filter residue for reaction to obtain a rare earth chloride solution; the solid-liquid ratio of the sodium sulfate to the waste polishing powder acid leaching solution is 200 g / L;
[0048] Extraction and separation: The obtained rare earth chloride solution is adjusted to a pH of 1.85 with aqueous ammonia, then mixed with a mixed extractant, shaken at a shaking speed of 200 rpm for 8 minutes, and then separated to obtain a first extract phase and a first raffinate phase; the volume ratio of the rare earth chloride solution to the mixed extractant is 1:1; the preparation method of the mixed extractant specifically comprises: uniformly mixing tributyl phosphate and kerosene at a volume ratio of 22.7:77.3, then adding n-octyl phosphoric acid to dissolve, to obtain a mixture of n-octyl phosphoric acid, tributyl phosphate, and kerosene; the concentration of n-octyl phosphoric acid in the mixture of n-octyl phosphoric acid, tributyl phosphate, and kerosene is 0.11 mol / L;
[0049] Stripping: The obtained first extract phase is mixed with an aqueous sulfuric acid solution, shaken at an oscillation speed of 200 rpm for 10 minutes, and then separated to obtain a second extract phase and a high-purity cerium sulfate solution; the volume ratio of the first extract phase to the aqueous sulfuric acid solution is 1:1, and the molar concentration of the aqueous sulfuric acid solution is 4 mol / L.
[0050] Example 4
[0051] A method for selectively separating and purifying rare earth cerium from waste polishing powder acid leaching solution, specifically comprising:
[0052] Primary purification: mixing the waste polishing powder acid leaching solution with sodium sulfate, reacting the mixture under heating and stirring at 95° C. for 30 minutes, performing solid-liquid separation after the reaction to obtain a first filter residue and a first filtrate, adding an excess of a 50% sodium hydroxide aqueous solution to the first filter residue for reaction, and performing solid-liquid separation after the reaction to obtain a second filter residue and a second filtrate; adding an excess of 0.5 mol / L dilute hydrochloric acid to the second filter residue for reaction to obtain a rare earth chloride solution; the solid-liquid ratio of the sodium sulfate to the waste polishing powder acid leaching solution is 200 g / L;
[0053] Extraction and separation: The obtained rare earth chloride salt solution is adjusted to a pH of 1.65 with aqueous ammonia, then mixed with a mixed extractant, and shaken at a shaking speed of 200 rpm for 10.5 minutes before separation to obtain a first extract phase and a first raffinate phase; the volume ratio of the rare earth chloride salt solution to the mixed extractant is 1:1; the preparation method of the mixed extractant specifically comprises: uniformly mixing tributyl phosphate and kerosene at a volume ratio of 27:73, then adding n-octyl phosphoric acid to dissolve, to obtain a mixture of n-octyl phosphoric acid, tributyl phosphate, and kerosene; the concentration of n-octyl phosphoric acid in the mixture of n-octyl phosphoric acid, tributyl phosphate, and kerosene is 0.11 mol / L;
[0054] Stripping: The obtained first extract phase is mixed with an aqueous sulfuric acid solution, shaken at an oscillation speed of 200 rpm for 10 minutes, and then separated to obtain a second extract phase and a high-purity cerium sulfate solution; the volume ratio of the first extract phase to the aqueous sulfuric acid solution is 1:1, and the molar concentration of the aqueous sulfuric acid solution is 4 mol / L.
[0055] Comparative Example 1
[0056] A method for selectively separating and purifying rare earth cerium from waste polishing powder acid leaching solution, specifically comprising:
[0057] Primary purification: mixing the waste polishing powder acid leaching solution with sodium sulfate, reacting the mixture under heating and stirring at 95° C. for 30 minutes, performing solid-liquid separation after the reaction to obtain a first filter residue and a first filtrate, adding an excess of a 50% sodium hydroxide aqueous solution to the first filter residue for reaction, and performing solid-liquid separation after the reaction to obtain a second filter residue and a second filtrate; adding an excess of 0.5 mol / L dilute hydrochloric acid to the second filter residue for reaction to obtain a rare earth chloride solution; the solid-liquid ratio of the sodium sulfate to the waste polishing powder acid leaching solution is 200 g / L;
[0058] Extraction and separation: The rare earth chloride solution obtained is adjusted to a pH of 1.77 with aqueous ammonia, then mixed with a mixed extractant, shaken at a rotation speed of 200 rpm for 10 minutes, and then separated to obtain a first extract phase and a first raffinate phase; the volume ratio of the rare earth chloride solution to the mixed extractant is 1:1; the preparation method of the mixed extractant specifically comprises: uniformly mixing tributyl phosphate and kerosene at a volume ratio of 24.5:75.5 to obtain a mixture of tributyl phosphate and kerosene;
[0059] Stripping: The obtained first extract phase is mixed with an aqueous sulfuric acid solution, shaken at an oscillation speed of 200 rpm for 10 minutes, and then separated to obtain a second extract phase and a high-purity cerium sulfate solution; the volume ratio of the first extract phase to the aqueous sulfuric acid solution is 1:1, and the molar concentration of the aqueous sulfuric acid solution is 4 mol / L.
[0060] The first extract phases obtained in Examples 1 to 4 and Comparative Example 1 were subjected to separation and detection of cerium and lanthanum elements. At the same time, the purity of cerium sulfate in the high-purity cerium sulfate solutions obtained in Examples 1 to 4 and Comparative Example 1 was tested. The test results are shown in Table 1.
[0061] Table 1 Test results
[0062] Example Cerium extraction rate Lanthanum extraction rate Separation factor β for cerium and lanthanum Cerium sulfate purity Example 1 64.95％ 1.93％ 94.60 99.9％ Example 2 64.21％ 1.12％ 157.60 99.7％ Example 3 68.11％ 1.88％ 111.70 99.5％ Example 4 60.15％ 1.51％ 97.94 99.8％ Comparative Example 1 27.45％ 4.07％ 8.93 88.93％
[0063] It can be seen from Examples 1 to 4 in Table 1 that the extraction rates of cerium are all above 60%, the extraction rates of lanthanum are all below 2%, and the purity of cerium sulfate is all above 99.5%. It can be seen that the method for selective separation and purification of rare earth cerium in waste polishing powder acid leaching solution of the present invention has a technical effect of selective extraction and purification of cerium; when the extraction rate of lanthanum is increased, the separation factor β of cerium and lanthanum will be relatively reduced. It can be seen that the separation factor β of cerium and lanthanum is related to the extraction rate of cerium and the extraction rate of lanthanum; comparing Example 1 and Comparative Example 1, the extraction rate of cerium in Comparative Example 1 is significantly reduced, while the extraction rate of lanthanum reaches 4.07%, the separation factor β of a single rare earth is only 8.93, and the purity of cerium sulfate in Comparative Example 1 is only 88.93%. It can be seen that in Comparative Example 1, the separation effect between single cerium and lanthanum is not good, and the selective extraction and purification effect of cerium is significantly reduced. It can be considered that the combination of n-octyl phosphoric acid and tributyl phosphate improves the effect of selective extraction and purification of cerium.
[0064] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.
Claims
1. A method for selectively separating and purifying rare earth cerium from waste polishing powder acid leaching solution, characterized in that: The method for selectively separating and purifying rare earth cerium in waste polishing powder acid leaching solution comprises: Primary purification: The waste polishing powder acid leaching solution is sequentially subjected to double salt precipitation, strong alkali conversion and low acid dissolution to obtain a rare earth chloride salt solution; Extraction and separation: adjusting the pH value of the obtained rare earth chloride salt solution by ammonia water, then mixing it with a mixed extractant, shaking it, and separating the liquids to obtain a first extraction phase and a first raffinate phase; Stripping: mixing the obtained first extract phase with a sulfuric acid aqueous solution, shaking and separating the liquids to obtain a second extract phase and a high-purity cerium sulfate solution; The mixed extractant is a mixture of n-octyl phosphoric acid, tributyl phosphate and kerosene.
2. The method for selectively separating and purifying rare earth cerium from waste polishing powder acid leaching solution according to claim 1, characterized in that: The method of subjecting the waste polishing powder acid leaching solution to double salt precipitation, strong alkali conversion and low acid dissolution in sequence to obtain the rare earth chloride salt solution specifically comprises: mixing the waste polishing powder acid leaching solution with sodium sulfate, performing a double salt precipitation reaction under heating and stirring conditions, performing solid-liquid separation after the reaction to obtain a first filter residue and a first filtrate, adding a sodium hydroxide aqueous solution to the first filter residue for reaction, and performing solid-liquid separation after the reaction to obtain a second filter residue and a second filtrate; and adding dilute hydrochloric acid to the second filter residue for reaction to obtain the rare earth chloride salt solution.
3. The method for selectively separating and purifying rare earth cerium from waste polishing powder acid leaching solution according to claim 2, characterized in that: The solid-liquid ratio of the sodium sulfate to the waste polishing powder acid leaching solution is 100g / L to 200g / L; the reaction temperature of the double salt precipitation reaction is 60°C to 100°C, and the reaction time of the double salt precipitation reaction is 10min to 90min.
4. The method for selectively separating and purifying rare earth cerium from waste polishing powder acid leaching solution according to claim 3, characterized in that: During the primary purification process, the amount of the diluted hydrochloric acid and the amount of the sodium hydroxide aqueous solution added are both excessive, the molar concentration of the diluted hydrochloric acid is 0.1 mol / L to 1 mol / L, and the mass concentration of the sodium hydroxide aqueous solution is 30% to 50%.
5. The method for selectively separating and purifying rare earth cerium from waste polishing powder acid leaching solution according to claim 4, characterized in that: The ammonia water adjusts the pH value of the rare earth chloride salt solution to 1.6-2; the volume ratio of the rare earth chloride salt solution to the mixed extractant is 3:1-1:
3.
6. The method for selectively separating and purifying rare earth cerium from waste polishing powder acid leaching solution according to claim 5, characterized in that: In the extraction and separation, the shaking time is 5 minutes to 20 minutes, and the shaking speed is 50 rpm to 300 rpm.
7. The method for selectively separating and purifying rare earth cerium from waste polishing powder acid leaching solution according to claim 6, characterized in that: The volume ratio of the first extraction phase to the aqueous sulfuric acid solution is 3:1 to 1:3, and the molar concentration of the aqueous sulfuric acid solution is 0.5 mol / L to 6 mol / L.
8. The method for selectively separating and purifying rare earth cerium from waste polishing powder acid leaching solution according to claim 7, characterized in that: In the stripping, the shaking time is 2 min to 15 min, and the shaking speed is 50 rpm to 300 rpm.
9. The method for selectively separating and purifying rare earth cerium from waste polishing powder acid leaching solution according to claim 8, characterized in that: The preparation method of the mixture of n-octyl phosphoric acid, tributyl phosphate and kerosene comprises: uniformly mixing tributyl phosphate and kerosene, then adding n-octyl phosphoric acid to dissolve the mixture to obtain the mixture of n-octyl phosphoric acid, tributyl phosphate and kerosene; the sum of the volume ratios of the tributyl phosphate and the kerosene is 100%, and the volume ratio of the tributyl phosphate to the kerosene is 10-30:70-90; and the concentration of the n-octyl phosphoric acid in the mixture of n-octyl phosphoric acid, tributyl phosphate and kerosene is 0.005 mol / L to 0.02 mol / L.