CN113832348A - Method for recovering rare earth and cobalt elements from rare earth permanent magnet muddy waste - Google Patents
Method for recovering rare earth and cobalt elements from rare earth permanent magnet muddy waste Download PDFInfo
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- CN113832348A CN113832348A CN202111101299.6A CN202111101299A CN113832348A CN 113832348 A CN113832348 A CN 113832348A CN 202111101299 A CN202111101299 A CN 202111101299A CN 113832348 A CN113832348 A CN 113832348A
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- rare earth
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- permanent magnet
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- 229910052761 rare earth metal Inorganic materials 0.000 title claims abstract description 98
- 239000002699 waste material Substances 0.000 title claims abstract description 84
- 150000002910 rare earth metals Chemical class 0.000 title claims abstract description 70
- 229910017052 cobalt Inorganic materials 0.000 title claims abstract description 48
- 239000010941 cobalt Substances 0.000 title claims abstract description 48
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 title claims abstract description 48
- 238000000034 method Methods 0.000 title claims abstract description 41
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 64
- 239000003792 electrolyte Substances 0.000 claims abstract description 50
- 238000002386 leaching Methods 0.000 claims abstract description 45
- 238000006243 chemical reaction Methods 0.000 claims abstract description 39
- 239000010802 sludge Substances 0.000 claims abstract description 38
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims abstract description 32
- 229910052742 iron Inorganic materials 0.000 claims abstract description 21
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 20
- 230000003647 oxidation Effects 0.000 claims abstract description 18
- 238000005868 electrolysis reaction Methods 0.000 claims abstract description 17
- -1 rare earth oxalate Chemical class 0.000 claims abstract description 14
- 239000000706 filtrate Substances 0.000 claims abstract description 12
- 239000007788 liquid Substances 0.000 claims abstract description 12
- 238000000926 separation method Methods 0.000 claims abstract description 12
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 10
- 239000001257 hydrogen Substances 0.000 claims abstract description 10
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 10
- 235000006408 oxalic acid Nutrition 0.000 claims abstract description 10
- 230000001590 oxidative effect Effects 0.000 claims abstract description 8
- 150000002500 ions Chemical class 0.000 claims abstract description 5
- 238000002156 mixing Methods 0.000 claims abstract description 5
- 238000001556 precipitation Methods 0.000 claims abstract description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 4
- 239000001301 oxygen Substances 0.000 claims abstract description 4
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 4
- 238000010349 cathodic reaction Methods 0.000 claims abstract description 3
- 238000004519 manufacturing process Methods 0.000 claims abstract description 3
- 238000011084 recovery Methods 0.000 claims description 17
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 8
- 238000000605 extraction Methods 0.000 claims description 8
- 239000012074 organic phase Substances 0.000 claims description 7
- 239000012535 impurity Substances 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 6
- 239000003795 chemical substances by application Substances 0.000 claims description 5
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical compound [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 claims description 4
- 238000005238 degreasing Methods 0.000 claims description 4
- 238000007885 magnetic separation Methods 0.000 claims description 4
- 239000003208 petroleum Substances 0.000 claims description 4
- 229910045601 alloy Inorganic materials 0.000 claims description 3
- 239000000956 alloy Substances 0.000 claims description 3
- 229910001431 copper ion Inorganic materials 0.000 claims description 3
- 238000004070 electrodeposition Methods 0.000 claims description 3
- 229910001404 rare earth metal oxide Inorganic materials 0.000 abstract description 7
- 229910001172 neodymium magnet Inorganic materials 0.000 description 21
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 20
- QJVKUMXDEUEQLH-UHFFFAOYSA-N [B].[Fe].[Nd] Chemical compound [B].[Fe].[Nd] QJVKUMXDEUEQLH-UHFFFAOYSA-N 0.000 description 20
- 229910000938 samarium–cobalt magnet Inorganic materials 0.000 description 20
- KPLQYGBQNPPQGA-UHFFFAOYSA-N cobalt samarium Chemical compound [Co].[Sm] KPLQYGBQNPPQGA-UHFFFAOYSA-N 0.000 description 19
- 239000000243 solution Substances 0.000 description 13
- 239000002253 acid Substances 0.000 description 8
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 8
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 6
- 239000003513 alkali Substances 0.000 description 6
- MEYVLGVRTYSQHI-UHFFFAOYSA-L cobalt(2+) sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Co+2].[O-]S([O-])(=O)=O MEYVLGVRTYSQHI-UHFFFAOYSA-L 0.000 description 5
- DABIZUXUJGHLMW-UHFFFAOYSA-H oxalate;samarium(3+) Chemical compound [Sm+3].[Sm+3].[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O DABIZUXUJGHLMW-UHFFFAOYSA-H 0.000 description 5
- 229910052772 Samarium Inorganic materials 0.000 description 4
- 230000008901 benefit Effects 0.000 description 4
- 239000010949 copper Substances 0.000 description 4
- 238000011978 dissolution method Methods 0.000 description 4
- 238000005265 energy consumption Methods 0.000 description 4
- 230000007613 environmental effect Effects 0.000 description 4
- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 description 4
- FAPWRFPIFSIZLT-UHFFFAOYSA-M sodium chloride Inorganic materials [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 4
- 239000002351 wastewater Substances 0.000 description 4
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 3
- QUXFOKCUIZCKGS-UHFFFAOYSA-N bis(2,4,4-trimethylpentyl)phosphinic acid Chemical compound CC(C)(C)CC(C)CP(O)(=O)CC(C)CC(C)(C)C QUXFOKCUIZCKGS-UHFFFAOYSA-N 0.000 description 3
- 238000011065 in-situ storage Methods 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- HJPBEXZMTWFZHY-UHFFFAOYSA-N [Ti].[Ru].[Ir] Chemical compound [Ti].[Ru].[Ir] HJPBEXZMTWFZHY-UHFFFAOYSA-N 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 229910000361 cobalt sulfate Inorganic materials 0.000 description 2
- 229940044175 cobalt sulfate Drugs 0.000 description 2
- KTVIXTQDYHMGHF-UHFFFAOYSA-L cobalt(2+) sulfate Chemical compound [Co+2].[O-]S([O-])(=O)=O KTVIXTQDYHMGHF-UHFFFAOYSA-L 0.000 description 2
- MULYSYXKGICWJF-UHFFFAOYSA-L cobalt(2+);oxalate Chemical compound [Co+2].[O-]C(=O)C([O-])=O MULYSYXKGICWJF-UHFFFAOYSA-L 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 238000009854 hydrometallurgy Methods 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 2
- 239000000696 magnetic material Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- FKTOIHSPIPYAPE-UHFFFAOYSA-N samarium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Sm+3].[Sm+3] FKTOIHSPIPYAPE-UHFFFAOYSA-N 0.000 description 2
- 239000011780 sodium chloride Substances 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- MBULCFMSBDQQQT-UHFFFAOYSA-N (3-carboxy-2-hydroxypropyl)-trimethylazanium;2,4-dioxo-1h-pyrimidine-6-carboxylate Chemical compound C[N+](C)(C)CC(O)CC(O)=O.[O-]C(=O)C1=CC(=O)NC(=O)N1 MBULCFMSBDQQQT-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910052692 Dysprosium Inorganic materials 0.000 description 1
- 241001190694 Muda Species 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 229910052771 Terbium Inorganic materials 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000009853 pyrometallurgy Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229910001954 samarium oxide Inorganic materials 0.000 description 1
- 229940075630 samarium oxide Drugs 0.000 description 1
- 238000000638 solvent extraction Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/006—Wet processes
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F17/00—Compounds of rare earth metals
- C01F17/20—Compounds containing only rare earth metals as the metal element
- C01F17/206—Compounds containing only rare earth metals as the metal element oxide or hydroxide being the only anion
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B23/00—Obtaining nickel or cobalt
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B59/00—Obtaining rare earth metals
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B1/00—Electrolytic production of inorganic compounds or non-metals
- C25B1/01—Products
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B15/00—Operating or servicing cells
- C25B15/08—Supplying or removing reactants or electrolytes; Regeneration of electrolytes
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- General Life Sciences & Earth Sciences (AREA)
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- Chemical Kinetics & Catalysis (AREA)
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Abstract
The application discloses a method for recovering rare earth and cobalt elements from rare earth permanent magnet muddy waste, which is characterized by comprising at least the following steps: (a) putting the leaching anode, the oxidation anode and the cathode into electrolyte for electrolysis; rare earth permanent magnet sludge waste is adsorbed on the leaching anode; production of H by oxygen evolution reaction in a leaching anode+Iron, cobalt and rare earth elements in the rare earth permanent magnet muddy waste on the leaching anode enter the electrolyte in the form of ions; oxidizing Fe in the electrolyte by the anode2+Is oxidized into Fe3+(ii) a OH produced by the cathodic reaction by hydrogen evolution−Mixing Fe3+With Fe (OH)3Precipitation in the form of (1); (b) after the electrolysis is stopped, the pH of the electrolyte is adjusted to cause Fe3+With Fe (OH)3Adding oxalic acid into the filtrate obtained in the step (b) after the solid-liquid separation, and obtaining rare earth oxalate and Co-containing rare earth oxalate through the solid-liquid separation2+The solution of (1); rare earth oxalate is roasted to obtain rare earth oxide.
Description
Technical Field
The invention belongs to the technical field of resource recovery and environmental protection, and relates to a method for recovering rare earth and cobalt elements from rare earth permanent magnet muddy waste.
Background
Rare earth permanent magnet materials such as neodymium iron boron (NdFeB) and samarium cobalt (SmCo) are widely used in many fields such as electronic information, the aviation industry, medical equipment, energy transportation and the like due to their characteristics of light weight, small volume, strong magnetism and the like. In the sintered neodymium-iron-boron magnetic material, the rare earth elements (including Nd accounting for about 90 percent and the balance of Pr, Dy and Tb) account for 30-33 wt.%, Fe accounts for 50-65 wt.%, Co accounts for 4-6 wt.%, and B accounts for 1-2 wt.%. In samarium cobalt magnet, Sm accounts for 18-30 wt.%, Co accounts for 50 wt.%, and Fe accounts for 20 wt.%. The rare earth magnetic material is hard and brittle, and in the machining process, 30-40% of raw materials become massive leftover materials, and mud waste materials such as oil sludge and mill mud due to the working procedures of cutting, grinding and the like. As rare earth and cobalt are important strategic metals, the recovery of rare earth and cobalt from rare earth permanent magnet waste materials has important significance.
At present, the methods for recycling rare earth permanent magnet waste materials, mainly neodymium iron boron and samarium cobalt waste materials at home and abroad comprise a direct reuse method, pyrometallurgy and hydrometallurgy. For rare earth permanent magnet bulk waste, a direct reuse method is generally adopted for producing new permanent magnet materials. For rare earth permanent magnet sludge-like waste, hydrometallurgy is the main method for treating the rare earth permanent magnet sludge-like waste, and comprises a hydrochloric acid optimum dissolution method, a hydrochloric acid full dissolution method and a sulfate double salt method. Among them, the hydrochloric acid optimum solution method is most widely used. Generally, iron removal is required before recovery of rare earth elements. The key step in iron removal is the formation of Fe3+Then adjusting the pH to convert Fe3+With Fe (OH)3Is removed. To form, the scrap may be subjected to oxidative roasting in a pretreatment stepOr adding H to the leaching solution after acid dissolution of the waste2O2Of Fe2+Conversion to Fe3+. The energy consumption of oxidizing roasting is high; h2O2The oxidation process is slow. In conclusion, the hydrochloric acid optimum dissolution method still needs to consume a large amount of strong acid and strong base, and the leaching time is long; a large amount of waste water is discharged, so that the environmental pollution is caused; the whole recovery process has long flow and high cost. In addition, most treatment processes only involve rare earth recovery and little mention is made of Co recovery for neodymium iron boron scrap. Therefore, the invention provides a green and economic recovery method, which realizes the high-efficiency recovery of rare earth and cobalt in neodymium iron boron and samarium cobalt mud-shaped waste materials.
Disclosure of Invention
The invention mainly solves the technical problem that the prior electrochemical technology is difficult to recover rare earth permanent magnet muddy waste with high resistance; also solves the problems of large acid-base consumption, serious environmental pollution and the like existing in the recovery treatment of rare earth alloy muddy waste by the existing hydrochloric acid optimum solution method. The invention aims to provide a method for recovering rare earth and cobalt from rare earth permanent magnet muddy waste. The method develops a double-anode electrolytic cell system with an impregnated anode and an oxidized anode, and utilizes the oxygen evolution reaction (2H) of the impregnated anode2O − 4e− → 4H+ + O2×) generated H+In-situ and continuous leaching of rare earth permanent magnet sludge waste; using an oxidizing anode pair of Fe2+Carrying out in-situ oxidation to form Fe3+（Fe2+ − e− → Fe3+). At the same time, the cathodic hydrogen evolution reaction (2H) is utilized2O + 2e−→ 2OH− + H2×) produced OH−To Fe3+The precipitate was removed. And finally, respectively recovering the rare earth and the cobalt by an oxalic acid precipitation method and a solvent extraction method. The electrochemical recovery method of rare earth permanent magnet muddy waste provided by the invention has the characteristics of environmental friendliness, simplicity, convenience, low cost and the like, the leaching efficiency and the acid and alkali consumption of the rare earth permanent magnet muddy waste can be regulated and controlled by adjusting the pH value of the electrolyte, the current/voltage and the like, the electrolyte (raffinate) can be recycled, and the large-scale industrial production can be realized.
In order to achieve the above object, the present invention provides a method for recovering rare earth and cobalt elements from rare earth permanent magnet sludge waste, comprising at least the following steps:
(a) putting the leaching anode, the oxidation anode and the cathode into electrolyte for electrolysis; rare earth permanent magnet sludge waste is adsorbed on the leaching anode; production of H by oxygen evolution reaction in a leaching anode+Iron, cobalt and rare earth elements in the rare earth permanent magnet muddy waste on the leaching anode enter the electrolyte in the form of ions; oxidizing Fe in the electrolyte by the anode2+Is oxidized into Fe3+(ii) a OH produced by the cathodic reaction by hydrogen evolution−Mixing Fe3+With Fe (OH)3Precipitation in the form of (1);
(b) after the electrolysis is stopped, the pH of the electrolyte is adjusted to cause Fe3+With Fe (OH)3Precipitating in a form of removing iron by solid-liquid separation;
(c) adding oxalic acid into the filtrate obtained after solid-liquid separation in the step (b), and then carrying out solid-liquid separation to obtain rare earth oxalate and Co-containing rare earth oxalate2+The solution of (1);
preferably, the pH of the electrolyte in the step (a) is 2.0-4.0.
Preferably, when the mass ratio of the leaching amount of the rare earth permanent magnet muddy waste to the electrolyte in the step (b) reaches 1: 4-6, the electrolysis of the leaching anode is stopped as a batch, the oxidation anode is continuously operated for 0.5-2 h, and Fe is added2+Complete oxidation to Fe3 +And then adjusting the pH of the electrolyte to Fe3+With Fe (OH)3Is precipitated.
Preferably, the rare earth oxalate is calcined to obtain the rare earth oxide.
Preferably, the pH of the electrolyte in the step (b) is adjusted to be 4.0-5.0.
Preferably, the molar ratio of the oxalic acid added in the step (c) to the rare earth elements in the solution is 1.5-2.5.
Preferably, the method further comprises:
(d) introducing Co into said step (c)2+Adding an extracting agent into the solution to extract and separate cobalt to obtain raffinate and a cobalt-loaded organic phase; subjecting the cobalt-loaded organic phase toAnd (4) carrying out back extraction to obtain a purified cobalt solution.
Preferably, the Co-containing2+The solution is added with an extractant for extracting and separating cobalt, and the O/A ratio of the extraction is preferably 4-1: 1.
Preferably, the extractant is a saponified Cyanex272 extractant.
Preferably, the stripping is performed using sulfuric acid.
Preferably, the raffinate is recovered and recycled to example step (4) as electrolyte.
Preferably, the leaching anode is provided with a magnet for adsorbing rare earth permanent magnet muddy waste.
Preferably, before electrolysis, the rare earth permanent magnet alloy oil sludge/mill mud waste is put into a degreasing tank, petroleum ether is added to remove oil stains in the waste, the waste is dried, and then nonmagnetic impurities are removed through magnetic separation.
Preferably, there are two of said cathodes, the first cathode producing OH by hydrogen evolution reaction−Mixing Fe3+With Fe (OH)3Is precipitated, and copper ion electrodeposition reaction is performed on the second cathode.
The rare earth permanent magnet sludge waste material in the present application includes but is not limited to rare earth permanent magnet cutting waste material, sintered blank, unqualified product and powder waste material formed by crushing rare earth permanent magnet waste material scrapped after the service period is over.
The invention has the following beneficial effects
The hydrochloric acid optimal dissolution method has the problems of high requirement on the granularity of rare earth permanent magnet muddy waste, high acid and alkali consumption, energy conservation and environmental protection along with the discharge of a large amount of waste water and the like. The invention utilizes an inert double-anode system to carry out in-situ leaching on rare earth permanent magnet muddy waste, synchronously realizes the removal of iron and successfully recovers rare earth and cobalt elements. The method has the advantages of short process flow, simple process conditions, low acid and alkali consumption, no waste water discharge, maximized improvement on the recovery value of the rare earth permanent magnet waste, considerable economic, social and environmental protection benefits, and capability of meeting the requirements of large-scale commercial application.
Drawings
FIG. 1 is a schematic view of an electrolytic cell for electrochemically treating neodymium iron boron sludge-like waste material according to the present invention.
Wherein: 1. neodymium iron boron sludge waste; 2. leaching the anode; 2', oxidizing the anode; 3. a cathode; 4. an electrolyte; 5. a magnet.
Figure 2 is a schematic of an electrolytic cell of the invention for electrochemically treating samarium cobalt sludge waste.
Wherein: 1. samarium cobalt sludge waste; 2. leaching the anode; 2', oxidizing the anode; 3. a cathode 1; 3', a cathode 2; 4. an electrolyte; 5. a magnet.
Detailed Description
Examples 1
(1) Pretreatment of neodymium iron boron sludge: putting the neodymium iron boron sludge waste into a degreasing tank, adding petroleum ether according to the volume ratio of 1:1 to remove oil stains and impurities in the waste, drying the cleaned neodymium iron boron sludge waste, and removing non-magnetic impurities through magnetic separation to obtain the dried clean neodymium iron boron sludge waste.
(2) Anode coating of neodymium iron boron sludge: in this example, a stainless steel sheet was used as the cathode and a commercial ruthenium iridium titanium mesh material was used as the inert anode (immersion anode + oxide anode). The neodymium iron boron sludge treated in example step (1) was uniformly coated on the surface of the leaching anode to a thickness of about 10 mm as shown in FIG. 1.
(3) Preparing electrolyte: 0.1 mol L of the mixture is prepared−1Sodium chloride (NaCl) solution was used as the electrolyte.
(4) Electrochemical leaching of neodymium iron boron sludge: as shown in FIG. 1, the anode for leaching coated with neodymium iron boron sludge from example step (2), the anode for oxidation and the cathode were placed in the electrolyte from example step (3) to conduct electrolysis. The electrolysis conditions were: the temperature is 20 ℃, the leaching anode current is 4.0A, the oxidation anode current is 2.0A, and the pH value of the electrolyte is maintained to be about 4.0 by dropwise adding concentrated hydrochloric acid. The (electro) chemical (semi) reaction equation involved in this step is as follows (RE: rare earth elements):
2H2O − 4e− → 4H+ + O2↓ (1-1) anode reaction (leaching anode)
2RE2Fe14B + 74H+ → 4RE3+ + 28Fe2+ + 2B3+ + 37H2Leaching reaction of waste material ↓ (1-2)
RE2O3 + 6H+ → 4RE3+ + 3H2O (1-3) waste leaching reaction
Fe2O3 + 6H+ → 4Fe3+ + 3H2O (1-4) waste leaching reaction
Fe2+ − e− → Fe3+(1-5) anodic reaction (Oxidation of Anode)
4Fe2+ + O2 + 4H+ → 4Fe3+ + 2H2O (1-6) oxidation reaction
Based on anode reaction and waste leaching reaction, elements in the neodymium iron boron mud-like waste enter the electrolyte in the form of ions in the electrolysis process. Meanwhile, the cathode mainly takes hydrogen evolution reaction and only has a small amount of iron ions (Fe)2+And Fe3+) Is deposited at the cathode in the form of metallic iron:
2H+ + 2e− → H2↓ (1-7) cathode reaction
2H2O + 2e− → 2OH− + H2↓ (1-8) cathode reaction
Fe2+ + 2e−→ Fe (1-9) cathode reaction
Fe3+ + 3e−→ Fe (1-10) cathode reaction
Cathodic hydrogen evolution reaction to produce OH−Resulting in an increase in the pH of the electrolyte. To make Fe2+Is efficiently oxidized to Fe in the form of soluble ions3+And dropwise adding hydrochloric acid into the electrolyte to maintain the pH of the electrolyte to be about 2.0-4.0.
(5) Removing iron: when the mass ratio of the neodymium iron boron sludge-like waste material to the electrolyte at the anode reaches 1:5, the electrolysis of the leaching anode is suspended as a batch. The oxidation anode is continuously operated for 1 h, and Fe is added2+Complete oxidation to Fe3+. Then adjusting the pH value of the electrolyte to 4.0 to enable Fe3+With Fe (OH)3Is precipitated in a form, iron is removed through solid-liquid separation,and obtaining a rare earth and Co2+The filtrate of (1).
(6) Selective precipitation of rare earth elements: using rare earth oxalates (e.g., K)sp (Neodymium oxalate) = 1.3 × 10−31) With cobalt (K) oxalatesp (cobalt oxalate) = 6.0 × 10−8) Difference in solubility towards rare earth and Co2+Adding oxalic acid solution into the filtrate, wherein the molar ratio of oxalic acid to the rare earth elements in the filtrate is 1.5, and selectively precipitating the rare earth elements in the form of rare earth oxalate. Obtaining rare earth oxalate precipitate and Co-containing by solid-liquid separation2+The filtrate of (1). The rare earth oxalate is roasted for 2h at 900 ℃, and then the high-purity rare earth oxide is obtained.
(7) And (3) recovering cobalt: will contain Co2+The filtrate is extracted by a saponified Cyanex272 extracting agent to separate cobalt, and the extraction ratio of O/A is preferably 2: 1. Obtaining raffinate and a cobalt-loaded organic phase; the cobalt-loaded organic phase is 0.1 mol L−1And carrying out back extraction on the sulfuric acid to obtain a cobalt sulfate solution, and carrying out evaporative crystallization to obtain the cobalt sulfate heptahydrate. The raffinate was recovered and returned to example step (4) for recycle as electrolyte.
Since the electrolyte (raffinate) can be recycled, the loss of the rare earth element and the cobalt element is almost 0. In the present example, the recovery rate of rare earth elements in the neodymium iron boron mud waste material is as high as 99.7%, and the purity of rare earth oxide is as high as 99.4%; the recovery rate of the cobalt element is as high as 99.9 percent, and the purity of the cobalt sulfate heptahydrate is as high as 99.7 percent; the energy consumption of electrochemical treatment of each kilogram of neodymium iron boron sludge waste is only 4.25 kWh, the acid consumption is only 0.5 kilogram, and the alkali consumption is only 0.05 kilogram.
EXAMPLES example 2
(1) Pretreatment of samarium cobalt sludge waste: samarium cobalt sludge (Sm-Co type 2:17, for example, Sm2(Co x1-- y Fe x Cu y )17) Putting the obtained product into a degreasing tank, adding petroleum ether according to the volume ratio of 1:1 to remove oil stains and impurities in the waste, drying the cleaned samarium-cobalt mud-like waste, and removing non-magnetic impurities through magnetic separation to obtain dry samarium-cobalt mudAs waste material.
(2) Anode coating of samarium cobalt sludge waste: in this example, a stainless steel sheet was used as the cathode and a commercial ruthenium iridium titanium mesh material was used as the inert anode (immersion anode + oxide anode). The samarium cobalt sludge treated in example step (1) was uniformly coated on the surface of the anode to a thickness of about 10 mm as shown in figure 2.
(3) Preparing electrolyte: 0.2 mol L of the mixture is prepared−1Ammonium chloride (NH)4Cl) solution as an electrolyte.
(4) Electrochemical leaching of samarium cobalt sludge waste: the electrolytic solution was prepared by placing the leached anode coated with samarium cobalt sludge from example step (2), the oxidized anode and the cathode in the electrolyte from example step (3), as shown in FIG. 2. The electrolysis conditions were: the temperature is 20 ℃, the leaching anode current is 4.0A, the oxidation anode current is 2.0A, and the pH value of the electrolyte is maintained to be about 4.0 by dropwise adding concentrated hydrochloric acid. The (electro) chemical (semi) reaction equation involved in this step is as follows (RE: rare earth elements):
2H2O − 4e− → 4H+ + O2↓ (2-1) anode reaction (leaching anode)
Sm2(Co x y1--Fe x Cu y )17 + 40H+ → 2Sm3+ + 17(1-x-y)Co2+ + 17xFe2+ + 17yCu2+ + 20H2Leaching reaction of waste material ↓ (2-2)
Sm2O3 + 6H+ → 2Sm3+ + 3H2O (2-3) waste leaching reaction
2CoO + 4H+ → 2Co2+ + 2H2O (2-4) waste leaching reaction
Fe2O3 + 6H+ → 2Fe3+ + 3H2O (2-5) waste leaching reaction
2CuO + 4H+ → 2Cu2+ + 2H2O (2-6) waste leaching reaction
Fe2+ − e− → Fe3+(2-7) YangPolar reaction (Oxidation anode)
4Fe2+ + O2 + 4H+ → 4Fe3+ + 2H2O (2-8) oxidation reaction
Based on the anodic reaction and the leaching reaction of the waste, elements in the samarium cobalt sludge waste enter the electrolyte in the form of ions during the electrolysis process. Meanwhile, the cathode 1 is mainly used for hydrogen evolution reaction and only has a small amount of iron ions (Fe)2+And Fe3+) Is deposited as metallic iron at the cathode, and mainly consists of copper ion electrodeposition reaction (obtaining metallic copper) at the cathode 2:
2H+ + 2e− → H2↓ (2-9) cathode 1 and 2 react
2H2O + 2e− → 2OH− + H2↓ (2-10) cathode 1 reaction
Cu2+ + 2e−→ Cu (2-11) cathode 2 reaction
Fe2+ + 2e−Reaction at cathode 1 of → Fe (2-12)
Fe3+ + 3e−Reaction at cathode 1 of → Fe (2-13)
Cathodic hydrogen evolution reaction to produce OH−Resulting in an increase in the pH of the electrolyte. To make Fe2+Is efficiently oxidized to Fe in the form of soluble ions3+And dropwise adding hydrochloric acid into the electrolyte to maintain the pH of the electrolyte to be about 2.0-4.0.
(5) Removing iron: when the mass ratio of the leaching amount of the samarium cobalt mud-like waste material at the anode to the electrolyte reached 1:5, the electrolysis of the leached anode was suspended as a batch. The oxidation anode is continuously operated for 0.5 h to oxidize Fe2+Complete oxidation to Fe3+. Then adjusting the pH value of the electrolyte to 4.0 to enable Fe3+With Fe (OH)3Is precipitated, is removed of iron by solid-liquid separation, and Sm-containing3+And Co2+The filtrate of (1).
(6) Selective precipitation of samarium: using samarium oxalate (e.g., K)sp (samarium oxalate) = 4.5 × 10−32) With cobalt (K) oxalatesp (cobalt oxalate) = 6.0 × 10−8) Difference in solubility towards rare earth and Co2+Adding oxalic acid into the filtrateThe molar ratio of oxalic acid to the rare earth elements in the filtrate is 1.5, and the samarium is selectively precipitated in the form of samarium oxalate. Obtaining samarium oxalate precipitate and Co-containing by solid-liquid separation2+The filtrate of (1). Roasting samarium oxalate at 900 ℃ for 2h to obtain the high-purity rare earth oxide.
(7) And (3) recovering cobalt: will contain Co2+The filtrate is extracted by a saponified Cyanex272 extracting agent to separate cobalt, and the extraction ratio of O/A is preferably 2: 1. Obtaining raffinate and a cobalt-loaded organic phase; the cobalt-loaded organic phase is 0.1 mol L−1And carrying out back extraction on the sulfuric acid to obtain a cobalt sulfate solution, and carrying out evaporative crystallization to obtain the cobalt sulfate heptahydrate. The raffinate was recovered and returned to example step (4) for recycle as electrolyte.
Note that, since the electrolyte (raffinate) can be recycled, the loss of samarium and cobalt elements is almost 0. In the example, the recovery rate of samarium element in the samarium cobalt mud waste is as high as 99.8 percent, and the purity of samarium oxide is as high as 99.6 percent; the recovery rate of the cobalt element is as high as 99.9 percent, and the purity of the cobalt sulfate heptahydrate is as high as 99.8 percent; and the energy consumption of electrochemical treatment of each kilogram of samarium cobalt mud waste is only 4.02 kWh, the acid consumption is only 0.7 kilogram, and the alkali consumption is only 0.035 kilogram.
The method for recovering rare earth elements and cobalt from neodymium iron boron and samarium cobalt mud-like waste has the following beneficial characteristics: the method realizes very high rare earth recovery efficiency and high-purity rare earth oxide and cobalt sulfate heptahydrate; the electrolyte (raffinate) is recycled, and the waste water discharge is avoided. The whole process has the advantages of low acid and alkali consumption, low energy consumption, simple treatment process and obvious industrialization advantage.
The above examples are only described to help understand the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
Claims (10)
1. A method for recovering rare earth and cobalt elements from rare earth permanent magnet sludge-like waste materials is characterized by comprising at least the following steps:
(a) putting the leaching anode, the oxidation anode and the cathode into electrolyte for electrolysis; rare earth permanent magnet sludge waste is adsorbed on the leaching anode; production of H by oxygen evolution reaction in a leaching anode+Iron, cobalt and rare earth elements in the rare earth permanent magnet muddy waste on the leaching anode enter the electrolyte in the form of ions; oxidizing Fe in the electrolyte by the anode2+Is oxidized into Fe3+(ii) a OH produced by the cathodic reaction by hydrogen evolution−Mixing Fe3+With Fe (OH)3Precipitation in the form of (1);
(b) after the electrolysis is stopped, the pH of the electrolyte is adjusted to cause Fe3+With Fe (OH)3Precipitating in a form of removing iron by solid-liquid separation;
(c) adding oxalic acid into the filtrate obtained after solid-liquid separation in the step (b), and then carrying out solid-liquid separation to obtain rare earth oxalate and Co-containing rare earth oxalate2 +The solution of (1).
2. The method for recovering rare earth and cobalt elements from rare earth permanent magnet sludge waste material according to claim 1, wherein the pH of the electrolyte in the step (a) is 2.0-4.0.
3. The method for recovering rare earth and cobalt from rare earth permanent magnet sludge waste according to claim 1, wherein when the mass ratio of leaching amount of rare earth permanent magnet sludge waste to electrolyte in the step (b) reaches 1: 4-6, electrolysis of the leaching anode is stopped as a batch, the oxidation anode is continuously operated for 0.5-2 h, and Fe is added2+Complete oxidation to Fe3+And then adjusting the pH of the electrolyte to Fe3+With Fe (OH)3Is precipitated.
4. The method for recovering rare earth and cobalt elements from rare earth permanent magnet sludge waste material according to claim 1, wherein the pH of the electrolyte in the step (b) is adjusted to 4.0-5.0.
5. The method for recovering rare earth and cobalt elements from rare earth permanent magnet sludge waste material as claimed in claim 1, wherein the molar ratio of the oxalic acid added in the step (c) to the rare earth elements in the solution is 1.5-2.5.
6. The method for recovering rare earth and cobalt elements from rare earth permanent magnet sludge waste material according to claim 1, further comprising:
(d) introducing Co into said step (c)2+Adding an extracting agent into the solution to extract and separate cobalt to obtain raffinate and a cobalt-loaded organic phase; and carrying out organic reverse extraction on the loaded cobalt to obtain a purified cobalt solution.
7. The method for recovering rare earth and cobalt elements from rare earth permanent magnet sludge waste material according to claim 1, wherein the Co-containing material is Co-containing2+Adding an extracting agent into the solution to extract and separate cobalt, wherein the extraction ratio of O/A is 4-1: 1.
8. The method for recovering rare earth and cobalt elements from rare earth permanent magnet sludge waste according to claim 1, wherein the leaching anode is provided with a magnet for adsorbing the rare earth permanent magnet sludge waste.
9. The method of claim 1, wherein the rare earth permanent magnet alloy sludge/mill mud waste is placed in a degreasing tank before electrolysis, petroleum ether is added to remove oil stains in the waste, the waste is dried, and then nonmagnetic impurities are removed by magnetic separation.
10. The process for recovery of rare earth and cobalt elements from rare earth permanent magnet sludge as claimed in claim 1, wherein there are two cathodes, the first one of which produces OH by hydrogen evolution reaction−Mixing Fe3+With Fe (OH)3Is precipitated, and copper ion electrodeposition reaction is performed on the second cathode.
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