CN1202459A - Process for preparing highly pure cerium oxide - Google Patents
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Abstract
Mixed rare earth sulfate solution containing three-valent cerium is introduced into the anode chamber of the double-chamber electrolyser for DC oxidation oxidizing three-valent cerium into four-valent cerium, which is extracted with selective organic four-valent cerium extractant. The organic phase carrying four-valent cerium into three-valent cerium with counter extraction solution containing reductant. The aqueous solution containing cerium is finally treated through routine process of chemical impurity removal, precipitation, drying and ignition to obtain high-purity cerium oxide product. The present invention is suitable for eletrolytic oxidation of cerium in sulfuric acid medium and subsequent extracting separation and purification to produce cerium products in industrial scale.
Description
The present invention relates to a kind of preparation method of high-purity cerium dioxide, be particularly suitable for that electrolytic oxidation in the sulfuric acid medium---organic solvent extraction prepares high-purity cerium dioxide, belong to the rare-earth wet method metallurgical technology.
At present, separation and Extraction cerium from mishmetal generally all utilizes its characteristic of appraising at the current rate, and at first trivalent cerium is oxidized to tetravalent state, and then utilize quadrivalent cerium on chemical property, marked difference to be arranged with other trivalent rare earth, promptly tetravalent cerium salt very easily hydrolysis with generating complex compound cerium is separated and purifies.
The method for oxidation of cerium is a lot, mainly contains air oxidation process, trial-production oxidation style, electrolytic oxidation and is in the photooxidation method etc. of theoretic discussion.Domestic production producer mostly adopts air oxidation process and potassium permanganate oxidation method: air oxidation process is used in industrial acquisition owing to inexpensive, but oxidation rate is slow, and efficient is low; Potassium permanganate oxidation method technology comparative maturity, but chemical reagent is more expensive, and give in the solution and introduced foreign ions such as manganese, potassium.After external suitability for industrialized production at present lays particular emphasis on and uses electrolytic oxidation with the cerium oxidation, extract the cerium oxide of purifying through molten Ji again, change into Industrial Co., Ltd etc. as French Luo Na company, Japanese river fine jade, but all be electrolytic oxidation in nitric acid medium, and the large-scale commercial production of electrolytic oxidation separating cerium yet there are no report in sulfuric acid medium.
The purpose of this invention is to provide electrolytic oxidation in a kind of sulfuric acid medium, selective organic solvent method of extraction, can effectively cerium be separated with impurity with other rare earth, thereby prepare highly purified cerium oxide.
The present invention is achieved in that
(1) is raw material to contain cerium mishmetal sulphuric acid soln, enters in the anolyte compartment of two-chamber-type electrolyzer, feed the direct current electrolytic oxidation, the trivalent cerium in the solution is oxidized to the tetravalence oxidation state, and other rare earth element still keeps trivalent state;
(2) the effusive quadrivalent cerium sulphuric acid soln that contains after the oxidation of above-mentioned anolyte compartment is entered in the multistage mixed settler extractor, with the ceric organic solvent extraction of one or more alternative extractions, isolate the ceric organic phase of load and contain trivalent rare earth raffinate water after mixing clarification, its raffinate water is produced few cerium mischmetal product through recycling;
(3) again with the ceric organic phase of the load acid solution reduction reextraction that contains reductive agent, mix the separation of clarification back and obtaining containing the cerous aqueous solution and organic phase, this organic phase is returned after washing and is recycled;
(4) will contain cerous aqueous solution method routinely at last, chemistry is removed non-rare earth impurities such as calcium, iron, manganese, silicon, oxalic acid precipitation, and solid-liquid separation, drying, calcination promptly gets CeO
2＞99.99% high-purity cerium oxide product.
The two-chamber-type cell construction that electrolytic oxidation of the present invention is used is made up of anolyte compartment [2], cathode compartment [6], ion-exchange membrane [8], anode [3] and negative electrode [7], ion-exchange membrane [8] is positioned in the middle of the electrolyzer, anolyte compartment [2] and cathode compartment [6] are separated, anode [3] and negative electrode [7] insert respectively in the electrolytic solution of anolyte compartment [2] and cathode compartment [6], anolyte compartment [2] is respectively equipped with feed liquid inlet [1] and oxidation liquid outlet [4] up and down, and cathode compartment [6] is respectively equipped with catholyte inlet [5] and outlet [9] up and down.The material of electrolyzer can be polyvinyl chloride or glass reinforced plastic, and anode material is the titanium and the titanium precious metal alloys of titanium or topped platinum, iridium; Cathode material is generally graphite, is preferably the Ti product of titanium, platinized titanium or topped palladium, and anode and negative electrode can be tabular or netted.Ion-exchange membrane be contain sulfonic group because of polymkeric substance make, also can be the synthetic homogeneous membrane or brush film.
Feed direct current during electrolysis, current density is 50～200A/m
2Enter the sulfuric acid rare earth feed liquid of anolyte compartment, it is 10～40g/l that its rare earth concentration contains rare earth oxide (REO),, cerium concentration (CeO
2/ REO) be 5-40g/l, optimum concn is 20～30g/l, solution acidity [H
+] be 0.1～2.5mol/l, optimum acidity [H
+] be 0.5～1.5mol/l, feed the aqueous sulfuric acid that cathode compartment recycles, its acidity [H
+] be 2.0～4.0mol/l.In the electrolytic process, aqueous temperature is controlled to be 20～80 ℃, and optimum temps is 40～50 ℃.Be provided with cooling installation in the electrolyzer, unsuitable too high to keep solution temperature.
Contain the sulphuric acid soln of quadrivalent cerium and trivalent rare earth behind the electrolytic oxidation and enter multistage mixed settler extractor after qualified after testing, extract with the ceric organic solvent of one or more alternative extractions.Extraction equipment generally adopts the multi-stage countercurrent cascade extraction for mixing the box extraction tank of clarification, also can adopt extraction of half adverse current and concurrent or back extraction.Organic extractant and quadrivalent cerium form complex compound and are extracted into organic phase, and other trivalent rare earth is then stayed in the aqueous solution, thereby obtain separating of quadrivalent cerium and trivalent rare earth.For reducing the extraction agent viscosity, improving liquidity, can to add a certain amount of inert organic solvents be that thinner mixes use with extraction agent.
Organic extractant commonly used is 21 ethylhexyl phosphoric acids, i.e. P204.Thinner adopts the sulphonated coal wet goods usually.The extraction agent that the present invention adopts is 1MP,204 one sulfonated kerosene.
Obtain the ceric organic phase of a kind of load and a kind of trivalent rare earth raffinate water that lacks cerium or essentially no cerium through above-mentioned extracting and separating, the few cerium mischmetal product of the recyclable process for producing of its water.The load quadrivalent cerium organic phase and the inorganic salt reductive agent acid solution of metal ion not, contact mixes in mixed settler extractor, carries out reduction reextraction.The present invention adopts hydrogen peroxide (H
2O
2) be the hydrochloric acid soln (i.e. 0.5～3.0NHcl+1--8%H of reductive agent
2O
2) through the multi-stage countercurrent thorough mixing, make quadrivalent cerium be reduced into trivalent cerium fully and entered aqueous phase by the hydrochloric acid back extraction, instead descend organic phase behind the rare earth after washing, can return and recycle.The cerium water method chemistry routinely that contains that reduction reextraction obtains is removed non-rare earth impurities such as calcium, iron, manganese, silicon, promptly gets CeO through oxalic acid precipitation, solid-liquid separation, drying, calcination again
2＞99.99% high-purity cerium oxide product.
The present invention compared with prior art has following advantage:
1, electrolytic oxidation is not introduced external impurity metal ion in the sulfuric acid medium, and electrolytic process is simple to operate, the oxidation ratio of process stabilizing, current efficiency and cerium is all higher.
2, electrolytic oxidation does not use more expensive chemical reagent, less investment, and production cost can reduce significantly.
3, the rare earth sulfate solution behind the electrolytic oxidation, can directly be connected the P2O4 extraction process and produce high-purity cerium dioxide, an advanced person's process for extracting cerium route has been opened up in further perfect separation and the purification that contains cerium in the rare earth ore concentrate vitriol oil high-temperature roasting infusion and the surplus liquid that divides into groups thereof.And simple for process, economical rationality realizes the serialization industrial production easily.
Below in conjunction with drawings and Examples the present invention is further described.
Description of drawings:
Fig. 1 is a two-chamber-type cell construction synoptic diagram;
Fig. 2 is the electrolytic oxidation extraction and separation technology schema of cerium of the present invention.
As shown in Figure 1, electrolytic oxidation is comprised of anode chamber [2], cathode chamber [6], amberplex [8], anode [3] and negative electrode [7] with the double chamber type cell construction, amberplex [8] in the middle of being positioned at electrolytic cell separates anode chamber [2] and cathode chamber [6], anode and negative electrode insert respectively in anode chamber and the cathode chamber, anode chamber [2] is respectively equipped with up and down feed liquid entrance [1] and oxidation solution outlet [4], and cathode chamber [6] is respectively equipped with up and down catholyte entrance [5] and outlet [9]. During electrolysis, contain cerium mishmetal sulfuric acid solution and enter anode chamber [2] from feed liquid entrance [1], the vitriolated aqueous solution enters cathode chamber [6] from catholyte entrance [5]. Between anode [3] and negative electrode [7] two electrodes, pass into direct current, because from exchange membrane [8] the two chambers of anode and cathode being separated, in anode chamber [2], trivalent cerium is oxidized to the tetravalence oxidation state. Contain quadrivalent cerium and trivalent rare earth sulfuric acid solution after electrolytic oxidation is finished flow out from oxidation solution outlet [4], connect next step extraction separation circuit. After adding sulfuric acid, the catholyte of catholyte outlet [9] outflow continues to recycle.
As shown in Figure 2, what contain that cerium mishmetal sulfuric acid liquid obtains after the oxidation of above-mentioned double chamber type electrolytic tank electrolysis contains quadrivalent cerium and trivalent rare earth sulfuric acid solution, enter in the multistage mixed settler extractor, extract with the ceric organic phase of selective extraction, quadrivalent cerium and organic solvent form complex compound and are extracted into organic phase, other trivalent rare earth is then stayed the raffinate aqueous phase, further reclaims few cerium mischmetal product. The ceric organic phase of load through the several grades of sulfuric acid solution countercurrent washings that contain 1.0～2.0mol/l after, with the strip liquor that contains reducing agent reduction reextraction in extraction tank, be about to the rare trivalent cerium that is reduced into of tetravalence and enter in the aqueous solution, the organic phase after the back extraction is returned extraction section and is recycled after washing. Back extraction obtains contains the cerium aqueous solution and carries out conventional method chemistry and remove the non-rare earth impurities such as calcium, iron, manganese, silicon, oxalic acid precipitation, and Separation of Solid and Liquid, drying, high temperature sintering namely get high-purity cerium oxide product.
Embodiment:
Electrolytic oxidation:
The volume 0.5m of two-chamber-type electrolyzer anode chamber
3, anode is the platinized titanium net, negative electrode is the titanium plate, adopts anion-exchange membrane.
Anolyte: sulfuric acid rare earth feed liquid rare earth concentration REO30-35g/l contains cerium CeO
2/ REO59～62%, acidity [H
+] 0.2～1.5mol/l, the feed liquid composition is listed in table 1.
Catholyte: 2.0～4.0mol/lH
2So
4
Electrolysis process condition: strength of current 500～800A, voltage 10-20V.
Electrolytic oxidation the results are shown in table 2.
The electrolytic process process stabilizing, current efficiency 46～49%, the oxidation ratio 90～96% of cerium.
Extracting and separating:
Feed liquid: contain the quadrivalent cerium sulphuric acid soln behind the electrolytic oxidation, rare earth concentration REO31～35g/l contains cerium CeO
2/ REO 61～63%.
The extraction process condition:
Organic phase: 1MP204-carbonization kerosene
Pickle solution: 1.0～2.0mol/l H
2So
4
Strip liquor: 0.5～3.0NHcl+1～8%H
2O
2
Adopt the extraction of mixed settler extractor 6 stage countercurrents, 9 grades of pickling, 4 grades of reduction reextractions, gained contain the cerium water through chemical subtraction, and oxalic acid precipitation, drying, calcination promptly get high-purity cerium oxide product, and table 4 and table 5 are listed in its interpretation of result, and cerium oxide purity is greater than 99.99%.
Electrolytic oxidation feed liquid composition table
Table 1
| Sequence number | Ree distribution pattern (%) | Non-rare earth (g/l) |
| ?La 2O 3?CeO 2?Pr 6O 11?Nd 2O 3Sm 2O 3?Eu 2O 3Gd 2O 3Y 2O 2 | cl -?Fe 2O 3?CaO 2?SiO 2?Mn?O 2 | |
| ?1 ?2 | ?35.02???59.42??5.06?????＜0.3???＜0.3?????＜0.3???＜0.3???＜0.3 ?30.88???62.34??6.38?????0.39????＜0.3?????＜0.3???＜0.3???0.01 | 1.38??0.08???1.005??0.02????0.158 2.60??0.12???1.000??0.002???- |
The electrolytic oxidation balance sheet table 2 of cerium
| Item number | ??[Ce 4+] ??(g/l) | ??[CeO 2] ????(g/l) | Oxidation ratio (%) | Current efficiency (%) | Remarks |
| ????8-1 ????8-2 ????8-3 ????8-4 ????8-5 ????8-6 | ????19.45 ????19.45 ????19.63 ????19.63 ????19.63 ????19.63 | ????20.72 ????20.72 ????20.54 ????20.91 ????20.92 ????20.72 | ????93.87 ????93.87 ????95.57 ????94.74 ????94.88 ????94.38 | ??48.77 ??48.77 ??49.70 ??49.26 ??49.34 ??49.08 | |
| ????8-7 ????8-8 ????8-9 | ????16.54 ????16.72 ????16.65 | ????17.82 ????17.89 ????17.82 | ????92.82 ????93.46 ????93.43 | ??46.28 ??47.77 ??47.78 | Electrolysis time 4.5 hours |
| ????8-10 ????8-11 ????8-12 ????8-13 ????8-14 ????8-15 ????8-16 | ????17.35 ????17.35 ????17.35 ????17.35 ????18.50 ????18.78 ????18.42 | ????18.98 ????19.16 ????19.08 ????18.98 ????20.25 ????20.36 ????20.39 | ????91.65 ????90.55 ????90.93 ????91.41 ????91.36 ????92.24 ????90.34 | ??48.88 ??48.29 ??48.29 ??48.75 ??48.51 ??48.96 ??48.98 | |
Non-rare earth analysis table 5 as a result in the product
| Numbering | CaO 2?Fe 2O 3?MnO 2???SiO 2Igloss (%) total amount of rare earth (%) |
| ?8-8 ?8-9 ?8-10 ?8-11 ?8-12 ?8-13 ?8-14 ?8-15 | ?0.034?＜0.005?＜0.005?＜0.005?0.11????99.87 ?0.034?＜0.005?＜0.005?＜0.005?0.13????99.41 ?0.058?＜0.005??0.0065?＜0.005?0.21????99.49 ?0.040?＜0.005??0.0064?＜0.005?0.27????99.78 ?0.040???0.005?＜0.005?＜0.005?0.72????99.10 ?0.042?＜0.005?＜0.005?＜0.005?0.80????99.62 ?0.059?＜0.005?＜0.005?＜0.005?0.68????99.50 ?0.048?＜0.005?＜0.005?＜0.005?0.57????99.82 |
Extraction feed liquid composition table table 3
| Sequence number | REO concentration (g/l) | Ree distribution pattern (%) | Non-rare earth (g/l) |
| La 2O 3CeO 2Pr 6O 11Nd 2O 3Sm 2O 3Eu 2O 3Gd 2O 3Y 2O 3 | ?cl -Fe 2O 3CaO 2SiO 2MnO 2 | ||
| ?1 ?2 | ????31.5 ????34.6 | 31.97??62.30??5.70???＜0.3????＜0.3??＜0.3??＜0.3??＜0.3 31.94??61.66??5.62???＜0.3????＜0.3??＜0.3??＜0.3??＜0.3 | ?2.01?0.140?0.726?0.138?0.015 ?3.16?0.119?0.804?0.145?0.017 |
Other rare earth analysis table 4 as a result in the product
| Numbering | La 2O 3?Pr 6O 11?Nd 2o 3?Sm 2O 3?Eu 2O 3?Gd 2O 3?Tb 4o 7?DY 2O 3?Ho 2O 3?Er 2O 3?Tm 2O 3?Yb 2O 3?Lu 2O 3?Y 2o 3 |
| ?8-8 ?8-9 ?8-10 ?8-11 ?8-12 ?8-13 ?8-14 ?8-15 | ＜0.002?＜0.008???＜0.002?＜0.0005?＜0.0003?＜0.001?＜0.002?＜0.0005?＜0.0005?＜0.0005?＜0.0005?＜0.0001?＜0.001??0.0064 ＜0.002?＜0.008???＜0.002?＜0.0005?＜0.0003?＜0.001?＜0.002?＜0.0005?＜0.0005?＜0.0005?＜0.0005?＜0.0001?＜0.001??0.0068 ＜0.002?＜0.008???＜0.002?＜0.001??＜0.0003?＜0.001?＜0.002?＜0.001??＜0.001??＜0.0005?＜0.0005?＜0.0001?＜0.001??0.0040 ＜0.002?＜0.008???＜0.002?＜0.001??＜0.0003?＜0.001?＜0.002?＜0.001??＜0.001??＜0.0005?＜0.0005?＜0.0001?＜0.001??0.0062 ＜0.002?＜0.008???＜0.002?＜0.001??＜0.0003?＜0.001?＜0.002?＜0.001??＜0.001??＜0.0005?＜0.0005?＜0.0001?＜0.001??0.0012 ＜0.002?＜0.008???＜0.002?＜0.001??＜0.0003?＜0.001?＜0.002?＜0.001??＜0.001??＜0.0005?＜0.0005?＜0.0001?＜0.001??0.0011 ＜0.002?＜0.008???＜0.002?＜0.001??＜0.0003?＜0.001?＜0.002?＜0.002??＜0.001??＜0.0005?＜0.0005?＜0.0001?＜0.001??0.0020 ＜0.002?＜0.008???＜0.002?＜0.001??＜0.0003?＜0.001?＜0.002?＜0.001??＜0.001??＜0.0005?＜0.0005?＜0.0001?＜0.001??0.00092 |
Claims (8)
1, a kind of preparation method of high-purity cerium dioxide, it comprises steps such as electrolytic oxidation, selective organic solvent extraction, reduction reextraction, chemical subtraction, precipitation, calcination, it is characterized in that:
(1) is raw material to contain cerium mishmetal sulphuric acid soln, enters in the anolyte compartment of two-chamber-type electrolyzer, feed the direct current electrolytic oxidation;
(2) the effusive quadrivalent cerium sulphuric acid soln that contains after the oxidation of above-mentioned anolyte compartment is entered in the multistage mixed settler extractor, with the ceric organic solvent extraction of one or more alternative extractions, mix the raffinate water of isolating the ceric organic phase of load after clarifying and containing trivalent rare earth;
(3), mix the separation of clarification back and obtaining containing the cerous aqueous solution and organic phase with the ceric organic phase of the load acid solution reduction reextraction that contains reductive agent;
(4) will contain the cerous aqueous solution at last and promptly get high-purity cerium dioxide (CeO with conventional method chemical subtraction, oxalic acid precipitation, drying, calcination
2＞99.99%) product.
2, according to the preparation method of the described high-purity cerium dioxide of claim 1 (1), it is characterized in that the rare earth sulfate solution raw material that electrolytic oxidation is used, it is 10～40g/l that its rare earth concentration contains rare earth oxide (REO), cerium concentration (CeO
2/ REO) be that 5～40g/l optimum concn is 20～30g/l; Solution acidity [H
+] be 0.1～2.5mol/l, optimum acidity is 0.5～1.5mol/l.
3,, it is characterized in that also comprising in the said organic extractant the aliphatic hydrocarbon that a kind of and extraction agent use with or the thinner of halohydrocarbon according to the preparation method of the described high-purity cerium dioxide of claim 1 (2).
4,, it is characterized in that said reductive agent is the inorganic salt reagent of metal ion not according to the preparation method of the described high-purity cerium dioxide of claim 1 (3).
5,, it is characterized in that the processing condition that extract with the back extraction separating cerium are according to the preparation method of claim 1,3,4 described high-purity cerium dioxides:
Feed liquid: rare earth concentration contains REO10～40g/l
Organic phase: 1MP204-kerosene
Washing lotion: 1.0～3.0mol/l H
2So
4
Strip liquor: 0.5～3.0NHcl+1～8%H
2O
2
6, for realizing the preparation method of the described high-purity cerium dioxide of claim 1 (1), it is characterized in that the two-chamber-type cell construction that electrolytic oxidation is used is by anolyte compartment [2], cathode compartment [6], ion-exchange membrane [8], anode [3] and negative electrode [7] are formed, ion-exchange membrane [8] is positioned in the middle of the electrolyzer, anolyte compartment [2] and cathode compartment [6] are separated, anode [3] and negative electrode [7] insert respectively in the electrolytic solution of anolyte compartment [2] and cathode compartment [6], anolyte compartment [2] is respectively equipped with feed liquid inlet [1] and oxidation liquid outlet [4] up and down, and cathode compartment [6] is respectively equipped with catholyte inlet [5] and outlet [9] up and down; Anode and negative electrode can be tabular or netted.
7, according to claim 1,6 described electrolytic oxidation electrolyzers, the material that it is characterized in that electrolyzer can be polyvinyl chloride or glass reinforced plastic, anode material is the titanium of titanium, topped platinum, iridium or the precious metal alloys of titanium, negative electrode material material is generally graphite, is preferably the Ti product of titanium, platinized titanium or topped palladium.
8,, it is characterized in that the feed liquid that anolyte compartment [2] enters is a rare earth sulfate solution according to claim 1,6,7 described electrolytic oxidation electrolyzers; The catholyte that cathode compartment [6] feeds is an aqueous sulfuric acid, its acidity [H
+] be 2.0～4.0mol/l; The electrolysis process condition: current density is 50～200A/m
2, the electrolytic solution temperature is 20～80 ℃, optimum temps is 40～50 ℃.
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|---|---|---|---|
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|---|---|---|---|
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100500568C (en) * | 2007-02-05 | 2009-06-17 | 金坛市西南化工研究所 | Method for preparing superfine high-purity cerium oxide by using rear earth ore sulfuric acid calcination products |
| CN104030336A (en) * | 2014-06-24 | 2014-09-10 | 安徽江南晶盛新材料有限公司 | Method for removing impurities such as iron and aluminum out of nano cerium oxide |
-
1997
- 1997-06-17 CN CN 97110686 patent/CN1202459A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100500568C (en) * | 2007-02-05 | 2009-06-17 | 金坛市西南化工研究所 | Method for preparing superfine high-purity cerium oxide by using rear earth ore sulfuric acid calcination products |
| CN104030336A (en) * | 2014-06-24 | 2014-09-10 | 安徽江南晶盛新材料有限公司 | Method for removing impurities such as iron and aluminum out of nano cerium oxide |
| CN104030336B (en) * | 2014-06-24 | 2016-01-20 | 安徽江南晶盛新材料有限公司 | The removing method of the impurity such as the iron aluminium in nano-cerium oxide |
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