CN113832348B - Method for recovering rare earth and cobalt element from rare earth permanent magnet mud-like waste - Google Patents
Method for recovering rare earth and cobalt element from rare earth permanent magnet mud-like waste Download PDFInfo
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- CN113832348B CN113832348B CN202111101299.6A CN202111101299A CN113832348B CN 113832348 B CN113832348 B CN 113832348B CN 202111101299 A CN202111101299 A CN 202111101299A CN 113832348 B CN113832348 B CN 113832348B
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- 239000002699 waste material Substances 0.000 title claims abstract description 93
- 229910052761 rare earth metal Inorganic materials 0.000 title claims abstract description 91
- 150000002910 rare earth metals Chemical class 0.000 title claims abstract description 67
- 229910017052 cobalt Inorganic materials 0.000 title claims abstract description 44
- 239000010941 cobalt Substances 0.000 title claims abstract description 44
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 title claims abstract description 44
- 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 108
- 239000003792 electrolyte Substances 0.000 claims abstract description 47
- 238000002386 leaching Methods 0.000 claims abstract description 44
- 238000006243 chemical reaction Methods 0.000 claims abstract description 43
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims abstract description 30
- 238000005868 electrolysis reaction Methods 0.000 claims abstract description 18
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 17
- 229910052742 iron Inorganic materials 0.000 claims abstract description 16
- 230000003647 oxidation Effects 0.000 claims abstract description 15
- 239000000706 filtrate Substances 0.000 claims abstract description 13
- 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
- -1 rare earth oxalate Chemical class 0.000 claims abstract description 10
- 230000001590 oxidative effect Effects 0.000 claims abstract description 7
- 238000001556 precipitation Methods 0.000 claims abstract description 6
- 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
- 239000010802 sludge Substances 0.000 claims description 16
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 8
- 239000012074 organic phase Substances 0.000 claims description 8
- 239000000463 material Substances 0.000 claims description 7
- 239000002244 precipitate Substances 0.000 claims description 7
- 239000012535 impurity Substances 0.000 claims description 6
- 238000005238 degreasing Methods 0.000 claims description 4
- 238000000605 extraction Methods 0.000 claims description 4
- 238000007885 magnetic separation Methods 0.000 claims description 4
- 239000003208 petroleum Substances 0.000 claims description 4
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical compound [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 claims description 3
- HJPBEXZMTWFZHY-UHFFFAOYSA-N [Ti].[Ru].[Ir] Chemical compound [Ti].[Ru].[Ir] HJPBEXZMTWFZHY-UHFFFAOYSA-N 0.000 claims description 3
- 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
- 238000000227 grinding Methods 0.000 claims description 3
- 239000003054 catalyst Substances 0.000 claims description 2
- 229910001404 rare earth metal oxide Inorganic materials 0.000 abstract description 6
- 229910001172 neodymium magnet Inorganic materials 0.000 description 21
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 20
- KPLQYGBQNPPQGA-UHFFFAOYSA-N cobalt samarium Chemical compound [Co].[Sm] KPLQYGBQNPPQGA-UHFFFAOYSA-N 0.000 description 20
- 229910000938 samarium–cobalt magnet Inorganic materials 0.000 description 20
- 238000011084 recovery Methods 0.000 description 16
- QJVKUMXDEUEQLH-UHFFFAOYSA-N [B].[Fe].[Nd] Chemical compound [B].[Fe].[Nd] QJVKUMXDEUEQLH-UHFFFAOYSA-N 0.000 description 14
- 238000004064 recycling Methods 0.000 description 9
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 8
- 239000002253 acid Substances 0.000 description 8
- 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
- 239000010949 copper Substances 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
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 4
- MULYSYXKGICWJF-UHFFFAOYSA-L cobalt(2+);oxalate Chemical compound [Co+2].[O-]C(=O)C([O-])=O MULYSYXKGICWJF-UHFFFAOYSA-L 0.000 description 4
- 238000005265 energy consumption Methods 0.000 description 4
- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 description 4
- 239000002351 wastewater Substances 0.000 description 4
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [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
- 230000007613 environmental effect Effects 0.000 description 3
- 238000011065 in-situ storage Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 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
- 229940044175 cobalt sulfate Drugs 0.000 description 2
- 229910000361 cobalt sulfate Inorganic materials 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
- 238000005520 cutting process Methods 0.000 description 2
- 238000011978 dissolution method Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 238000009854 hydrometallurgy Methods 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 239000000696 magnetic material Substances 0.000 description 2
- 230000001376 precipitating effect Effects 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 150000003839 salts Chemical class 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
- 229910052771 Terbium Inorganic materials 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- 235000019270 ammonium chloride Nutrition 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000003411 electrode reaction Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000005516 engineering process 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
- 150000002739 metals Chemical class 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000009853 pyrometallurgy Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 229910001954 samarium oxide Inorganic materials 0.000 description 1
- 229940075630 samarium oxide Drugs 0.000 description 1
- FKTOIHSPIPYAPE-UHFFFAOYSA-N samarium(iii) oxide Chemical compound [O-2].[O-2].[O-2].[Sm+3].[Sm+3] FKTOIHSPIPYAPE-UHFFFAOYSA-N 0.000 description 1
- 238000000638 solvent extraction Methods 0.000 description 1
Classifications
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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
-
- 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
-
- 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
-
- 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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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Metallurgy (AREA)
- Materials Engineering (AREA)
- Geology (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Inorganic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
The application discloses a method for recovering rare earth and cobalt elements from rare earth permanent magnet mud-like waste, which is characterized by comprising at least the following steps: (a) Placing the leaching anode, the oxidation anode and the cathode in electrolyte for electrolysis; rare earth permanent magnet mud-like waste is adsorbed on the leaching anode; leaching the anode to produce H by oxygen evolution reaction + Iron, cobalt and rare earth elements in the rare earth permanent magnet mud-shaped waste on the anode enter electrolyte in an ionic form; oxidizing the Fe in the anode to obtain Fe 2+ Oxidation to Fe 3+ The method comprises the steps of carrying out a first treatment on the surface of the OH produced by hydrogen evolution reaction at cathode − Fe is added to 3+ By Fe (OH) 3 Form precipitation of (c); (b) After stopping the electrolysis, the pH of the electrolyte is adjusted to make Fe 3+ By Fe (OH) 3 Adding oxalic acid into the filtrate after solid-liquid separation in step (b), and then carrying out solid-liquid separation to obtain rare earth oxalate and Co-containing solution 2+ Is a solution of (a); and roasting the rare earth oxalate to obtain the 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 mud-like waste.
Background
Rare earth permanent magnet materials, such as neodymium iron boron (NdFeB) and samarium cobalt (SmCo), are widely applied to a plurality of fields of electronic information, aviation industry, medical equipment, energy traffic and the like due to the characteristics of light weight, small volume, strong magnetism and the like. In the sintered NdFeB magnet, rare earth elements (including Nd accounting for about 90%, pr, dy and Tb accounting for the rest) 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 the samarium cobalt magnetic material, the Sm content is 18-30wt%, the Co content is 50wt%, and the Fe content is 20wt%. The rare earth magnetic material is hard and brittle, and in the machining process, 30-40% of raw materials become blocky scraps, sludge like oil sludge, grinding sludge and the like due to working procedures such as cutting, polishing and the like. Since rare earth and cobalt are important strategic metals, the recovery of rare earth and cobalt from rare earth permanent magnet waste is of great 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 include direct recycling method, pyrometallurgy and hydrometallurgy. For rare earth permanent magnet bulk waste, a direct recycling method is generally adopted for producing new permanent magnet materials. For rare earth permanent magnet mud-like waste, hydrometallurgy is a main method for treating the rare earth permanent magnet mud-like waste, and comprises a hydrochloric acid eulyzing method, a hydrochloric acid total lyzing method and a sulfuric acid double salt method. Among them, the eugenolysis method of hydrochloric acid is most widely used. Generally, iron needs to be removed before the rare earth elements are recovered. The key step of iron removal is the formation of Fe 3+ Then by adjusting the pH, fe 3+ By Fe (OH) 3 Is removed in the form of (c). To form, the waste material may be subjected to oxidative calcination in a pretreatment step, or H may be added to the leaching solution after acid leaching of the waste material 2 O 2 Fe is added with 2+ Conversion to Fe 3+ . The energy consumption of oxidizing roasting is high; h 2 O 2 The oxidation process is slow. In short, the hydrochloric acid eutectoid method still needs to consume a large amount of strong acid and alkali, and the leaching time is long; a large amount of wastewater is discharged, so that environmental pollution is caused; the whole recovery process flow is long and the cost is high. In addition, for neodymium iron boron waste, most treatment processes only involve rare earth recovery, and there is little mention of Co recovery. Therefore, the invention provides a green and economic recovery method for realizing the efficient recovery of rare earth and cobalt in the neodymium iron boron and samarium cobalt mud-like waste.
Disclosure of Invention
The invention mainly solves the technical problem that the existing electrochemical technology is difficult to recycle the rare earth permanent magnet mud-shaped waste with high resistance; solves the problems of high acid and alkali consumption, serious environmental pollution and the like existing in the prior hydrochloric acid optimal dissolution method for recycling rare earth alloy mud-like waste. The invention aims to provide a method for recycling rare earth and cobalt from rare earth permanent magnet mud-like waste. The method developed a double anode cell system comprising an leached anode and an oxidized anode, utilizing the leached anode oxygen evolution reaction (2H 2 O − 4e − → 4H + + O 2 ≡), produced H + Carrying out in-situ and continuous leaching on rare earth permanent magnet mud-shaped waste; fe with anode oxide 2+ Performing in-situ oxidation to form Fe 3+ （Fe 2+ − e − → Fe 3+ ). At the same time, the cathode hydrogen evolution reaction (2H 2 O + 2e − → 2OH − + H 2 ≡), produced OH − For Fe 3+ And (5) performing precipitation removal. Finally, rare earth and cobalt are respectively recovered by an oxalic acid precipitation method and a solvent extraction method. The electrochemical recovery method of the rare earth permanent magnet mud-shaped waste material has the characteristics of green, simplicity, convenience, low cost and the like, the leaching efficiency and the acid-base consumption of the rare earth permanent magnet mud-shaped waste material can be regulated and controlled by regulating the pH value, the current/voltage and the like of the electrolyte, and the electrolyte (raffinate) can be recycled, so that 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 mud-like waste, comprising at least the steps of:
(a) Placing the leaching anode, the oxidation anode and the cathode in electrolyte for electrolysis; rare earth permanent magnet mud-like waste is adsorbed on the leaching anode; leaching the anode to produce H by oxygen evolution reaction + Iron, cobalt and rare earth elements in the rare earth permanent magnet mud-shaped waste on the anode enter electrolyte in an ionic form; oxidizing the Fe in the anode to obtain Fe 2+ Oxidation to Fe 3+ The method comprises the steps of carrying out a first treatment on the surface of the OH produced by hydrogen evolution reaction at cathode − Fe is added to 3+ By Fe (OH) 3 Form precipitation of (c);
(b) After stopping the electrolysis, the pH of the electrolyte is adjusted to make Fe 3+ By Fe (OH) 3 Removing iron by solid-liquid separation;
(c) Adding oxalic acid into the filtrate after solid-liquid separation in step (b), and obtaining rare earth oxalate and Co-containing solution through solid-liquid separation 2+ Is a solution of (a);
preferably, the pH of the electrolyte in the step (a) is 2.0 to 4.0.
Preferably, when the mass ratio of the leaching amount of the rare earth permanent magnet mud-shaped waste material to the electrolyte in the step (b) reaches 1:4-6, stopping the electrolysis of the leaching anode as a batch, continuously operating the oxidation anode for 0.5-2 h, and adding Fe 2+ Fully oxidized to Fe 3 + Then adjusting the pH of the electrolyte to lead Fe 3+ By Fe (OH) 3 Is precipitated in the form of (a).
Preferably, the rare earth oxalate is calcined to obtain the rare earth oxide.
Preferably, in the step (b), the pH of the electrolyte is adjusted to 4.0-5.0.
Preferably, the molar ratio of oxalic acid added in the step (c) to the rare earth element in the solution is 1.5-2.5.
Preferably, the method further comprises:
(d) To said step (c) Co-containing 2+ Adding an extractant into the solution of the catalyst to extract and separate cobalt, so as to obtain raffinate and a cobalt-loaded organic phase; and (3) reversely extracting the cobalt-loaded organic phase to obtain a purified cobalt solution.
Preferably, the Co-containing material 2+ And adding an extractant into the solution to extract and separate cobalt, wherein the extraction ratio O/A is preferably 4-1:1.
Preferably, the extractant is a saponified Cyanex272 extractant.
Preferably, the stripping is performed with sulfuric acid.
Preferably, the raffinate is recovered and recycled back to example step (4) for recycling as electrolyte.
Preferably, a magnet for adsorbing rare earth permanent magnet mud-like waste is arranged on the leaching anode.
Preferably, the rare earth permanent magnet alloy oil sludge/grinding sludge waste is put into a degreasing tank before electrolysis, petroleum ether is added to remove greasy dirt in the waste, and the waste is dried and then non-magnetic impurities are removed through magnetic separation.
Preferably, the number of the cathodes is two, and the first cathode generates OH through hydrogen evolution reaction − Fe is added to 3+ By Fe (OH) 3 In the form of a precipitate, copper ion electrodeposition reactions occur at the second cathode.
The rare earth permanent magnet mud-shaped waste material in the application comprises, 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 service expiration.
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 mud-shaped waste, large acid-base consumption, energy conservation, environmental protection and the like along with the discharge of a large amount of wastewater. The invention utilizes an inert double-anode system to carry out in-situ leaching on rare earth permanent magnet mud-like waste, and synchronously realizes iron removal, thereby successfully recovering rare earth and cobalt elements. The method has the advantages of short process flow, simple process condition, less acid and alkali consumption, no wastewater discharge, maximized improvement of the recovery value of the rare earth permanent magnet waste, considerable economic, social and environmental protection benefits and capability of meeting the large-scale commercial application requirements.
Drawings
FIG. 1 is a schematic view of an electrolytic cell for electrochemically treating NdFeB sludge-like waste material according to the present invention.
Wherein: 1. neodymium iron boron mud-like waste; 2. leaching the anode; 2', oxidizing an anode; 3. a cathode; 4. an electrolyte; 5. a magnet.
FIG. 2 is a schematic diagram of an electrolytic cell for electrochemically treating samarium cobalt sludge waste according to the present invention.
Wherein: 1. samarium cobalt mud-like waste; 2. leaching the anode; 2', oxidizing an anode; 3. a cathode 1;3', cathode 2; 4. an electrolyte; 5. a magnet.
Detailed Description
Example 1
(1) Pretreatment of neodymium iron boron mud-like waste: and (3) putting the neodymium iron boron mud-shaped waste into a degreasing tank, adding petroleum ether according to a volume ratio of 1:1 to remove greasy dirt and impurities in the waste, drying the cleaned neodymium iron boron mud-shaped waste, and removing non-magnetic impurities through magnetic separation to obtain the dried and clean neodymium iron boron mud-shaped waste.
(2) Anode coating of neodymium iron boron mud-like waste: in this example, stainless steel sheet was used as the cathode and commercial ruthenium iridium titanium mesh material was used as the inert anode (leaching anode + oxidation anode). As shown in FIG. 1, the NdFeB sludge-like waste material treated in the example step (1) was uniformly coated on the surface of the leached anode to a thickness of about 10 a mm a.
(3) Preparing an electrolyte: preparation of 0.1 mol L −1 Sodium chloride (NaCl) solution was used as the electrolyte.
(4) Electrochemical leaching of neodymium iron boron mud-like waste: according to FIG. 1, the leached anode, the oxidized anode and the cathode of the NdFeB mud-like waste coated in the example step (2) are placed in the electrolyte of the example step (3) for electrolysis. The electrolysis conditions are as follows: the temperature was 20 ℃, the anodic current for leaching was 4.0A, the anodic current for oxidation was 2.0A, and the pH of the electrolyte was maintained at about 4.0 by dropwise addition of concentrated hydrochloric acid. The (electro) chemical (semi) reaction equation involved in this step is as follows (RE: rare earth element):
2H 2 O − 4e − → 4H + + O 2 positive electrode reaction of ∈ (1-1) (leaching positive electrode)
2RE 2 Fe 14 B + 74H + → 4RE 3+ + 28Fe 2+ + 2B 3+ + 37H 2 Waste ∈ (1-2) leaching reaction
RE 2 O 3 + 6H + → 4RE 3+ + 3H 2 O (1-3) waste leaching reaction
Fe 2 O 3 + 6H + → 4Fe 3+ + 3H 2 O (1-4) waste leaching reaction
Fe 2+ − e − → Fe 3+ (1-5) anodic reaction (oxidized anode)
4Fe 2+ + O 2 + 4H + → 4Fe 3+ + 2H 2 O (1-6) oxidation reaction
Elements in the neodymium iron boron mud-like waste enter the electrolyte in an ionic form during the electrolysis process based on the anode reaction and the waste leaching reaction. At the same time, the cathode mainly generates hydrogen evolution reaction, and only small amount of iron ions (Fe 2+ And Fe (Fe) 3+ ) At the cathode, the metal iron is deposited:
2H + + 2e − → H 2 cathode reaction of ∈ (1-7)
2H 2 O + 2e − → 2OH − + H 2 Cathode reaction of ∈ (1-8)
Fe 2+ + 2e − Fe (1-9) cathode reaction
Fe 3+ + 3e − Fe (1-10) cathode reaction
Cathodic hydrogen evolution reaction to OH − Resulting in an increase in the pH of the electrolyte. To make Fe 2+ Is efficiently oxidized to Fe in the form of soluble ion 3+ Hydrochloric acid is added dropwise to the electrolyte to maintain the pH of the electrolyte at about 2.0-4.0.
(5) Iron removal: when the mass ratio of the leaching amount of the NdFeB mud-like waste material at the anode to the electrolyte reaches 1:5, the electrolysis of the leached anode is suspended as a batch. The oxidized anode continues to run for 1 h to lead Fe to 2+ Fully oxidized to Fe 3+ . Then adjusting the pH value of the electrolyte to 4.0 to enable Fe to be 3+ By Fe (OH) 3 Removing iron by solid-liquid separation and obtaining rare earth and Co-containing precipitate 2+ Is a filtrate of (a) a (b).
(6) Selective precipitation of rare earth elements: rare earth oxalate (e.g., K) sp (neodymium oxalate) = 1.3 × 10 −31 ) With cobalt oxalate (K) sp (cobalt oxalate) = 6.0 × 10 −8 ) Solubility difference to rare earth and Co containing 2+ Adding oxalic acid solution into the filtrate, wherein the molar ratio of oxalic acid to rare earth element in the filtrate is 1.5, and selectively precipitating the rare earth element in the form of rare earth oxalate. Obtaining rare earth oxalate precipitate and Co-containing precipitate through solid-liquid separation 2+ Is a filtrate of (a) a (b). Rare earth grassThe high-purity rare earth oxide is obtained after the acid salt is roasted at 900 ℃ for 2 h.
(7) Recovery of cobalt: will contain Co 2+ The filtrate of (2) is extracted and separated into cobalt by using a saponified Cyanex272 extractant, wherein 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 −1 And (3) back-extracting the sulfuric acid to obtain a cobalt sulfate solution, and evaporating and crystallizing to obtain the cobalt sulfate heptahydrate. The raffinate was recovered and returned to example step (4) for recycling as electrolyte.
Since the electrolyte (raffinate) can be recycled, the loss of rare earth element and cobalt element is almost 0. In the example, the recovery rate of rare earth elements in the NdFeB mud-like waste is up to 99.7%, and the purity of rare earth oxide is up to 99.4%; the recovery rate of cobalt element is up to 99.9%, and the purity of cobalt sulfate heptahydrate is up to 99.7%; the electrochemical treatment energy consumption of each kilogram of neodymium iron boron mud-shaped waste is only 4.25 kWh, the acid consumption is only 0.5 kilogram, and the alkali consumption is only 0.05 kilogram.
Example 2 of the embodiment
(1) Pretreatment of samarium cobalt mud-like waste: sludge waste of samarium cobalt (for example, sm-Co of 2:17 type, sm 2 (Co x1-- y Fe x Cu y ) 17 ) And (3) placing the waste material into a degreasing tank, adding petroleum ether according to the volume ratio of 1:1 to remove greasy dirt and impurities in the waste material, drying the cleaned samarium cobalt mud-like waste material, and removing non-magnetic impurities through magnetic separation to obtain dry clean samarium cobalt mud-like waste material.
(2) Anode coating of samarium cobalt mud waste: in this example, stainless steel sheet was used as the cathode and commercial ruthenium iridium titanium mesh material was used as the inert anode (leaching anode + oxidation anode). As shown in FIG. 2, the sludge-like waste of samarium cobalt treated in the example step (1) was uniformly coated on the surface of the anode to a thickness of about 10 a mm a.
(3) Preparing an electrolyte: preparation of 0.2 mol L −1 Ammonium chloride (NH) 4 Cl) solution as electrolyte.
(4) Electrochemical leaching of samarium cobalt sludge waste: according to FIG. 2, the leached anode, oxidized anode and cathode coated with samarium cobalt sludge waste material of example step (2) were placed in the electrolyte of example step (3) to conduct electrolysis. The electrolysis conditions are as follows: the temperature was 20 ℃, the anodic current for leaching was 4.0A, the anodic current for oxidation was 2.0A, and the pH of the electrolyte was maintained at about 4.0 by dropwise addition of concentrated hydrochloric acid. The (electro) chemical (semi) reaction equation involved in this step is as follows (RE: rare earth element):
2H 2 O − 4e − → 4H + + O 2 anode reaction ∈ (2-1) (leaching anode)
Sm 2 (Co x y1-- Fe x Cu y ) 17 + 40H + → 2Sm 3+ + 17(1-x-y)Co 2+ + 17xFe 2+ + 17yCu 2+ + 20H 2 Waste ∈ (2-2) leaching reaction
Sm 2 O 3 + 6H + → 2Sm 3+ + 3H 2 O (2-3) waste leaching reaction
2CoO + 4H + → 2Co 2+ + 2H 2 O (2-4) waste leaching reaction
Fe 2 O 3 + 6H + → 2Fe 3+ + 3H 2 O (2-5) waste leaching reaction
2CuO + 4H + → 2Cu 2+ + 2H 2 O (2-6) waste leaching reaction
Fe 2+ − e − → Fe 3+ (2-7) anodic reaction (oxidized anode)
4Fe 2+ + O 2 + 4H + → 4Fe 3+ + 2H 2 O (2-8) oxidation reaction
Elements in the samarium cobalt mud waste enter the electrolyte in ionic form during electrolysis based on the anodic reaction and the waste leaching reaction. At the same time, the cathode 1 is mainly hydrogen evolution reaction, and only small amount of iron ions (Fe 2+ And Fe (Fe) 3+ ) Is deposited as metallic iron at the cathode and copper ion electrodeposition reactions predominate at the cathode 2 (metal is obtainedCopper):
2H + + 2e − → H 2 reaction of ∈ (2-9) cathodes 1 and 2
2H 2 O + 2e − → 2OH − + H 2 Cathode 1 reaction of ∈ (2-10)
Cu 2+ + 2e − Cu (2-11) cathode 2 reaction
Fe 2+ + 2e − Fe (2-12) cathode 1 reaction
Fe 3+ + 3e − Reaction of Fe (2-13) cathode 1
Cathodic hydrogen evolution reaction to OH − Resulting in an increase in the pH of the electrolyte. To make Fe 2+ Is efficiently oxidized to Fe in the form of soluble ion 3+ Hydrochloric acid is added dropwise to the electrolyte to maintain the pH of the electrolyte at about 2.0-4.0.
(5) Iron removal: when the mass ratio of the leaching amount of the samarium cobalt sludge waste at the anode to the electrolyte reaches 1:5, the electrolysis of the leached anode is suspended as a batch. The oxidation anode continues to run for 0.5 to h to lead Fe to 2+ Fully oxidized to Fe 3+ . Then adjusting the pH value of the electrolyte to 4.0 to enable Fe to be 3+ By Fe (OH) 3 Removing iron by solid-liquid separation and obtaining Sm-containing 3+ And Co 2+ Is a filtrate of (a) a (b).
(6) Selective precipitation of samarium: samarium oxalate (e.g., K) sp (samarium oxalate) = 4.5 × 10 −32 ) With cobalt oxalate (K) sp (cobalt oxalate) = 6.0 × 10 −8 ) Solubility difference to rare earth and Co containing 2+ Adding oxalic acid solution into the filtrate, wherein the molar ratio of oxalic acid to rare earth element in the filtrate is 1.5, and selectively precipitating samarium in the form of samarium oxalate. Obtaining samarium oxalate precipitate and Co-containing precipitate through solid-liquid separation 2+ Is a filtrate of (a) a (b). And roasting samarium oxalate at 900 ℃ for 2h to obtain the high-purity rare earth oxide.
(7) Recovery of cobalt: will contain Co 2+ The filtrate of (2) is extracted and separated into cobalt by using a saponified Cyanex272 extractant, wherein the extraction ratio of O/A is preferably 2:1. Obtaining raffinate and a cobalt-loaded organic phase; the cobalt-loaded organic phase is adopted to be 0.1mol L −1 And (3) back-extracting the sulfuric acid to obtain a cobalt sulfate solution, and evaporating and crystallizing to obtain the cobalt sulfate heptahydrate. The raffinate was recovered and returned to example step (4) for recycling as electrolyte.
Since the electrolyte (raffinate) can be recycled, the loss of samarium element and cobalt element was almost 0. In the example, the recovery rate of samarium element in the samarium cobalt mud waste is up to 99.8%, and the purity of samarium oxide is up to 99.6%; the recovery rate of cobalt element is up to 99.9%, and the purity of cobalt sulfate heptahydrate is up to 99.8%; the electrochemical treatment energy consumption of each kilogram of samarium cobalt mud-shaped 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 the mud-like waste of neodymium iron boron and samarium cobalt has the following beneficial characteristics: realizing very high rare earth recovery efficiency, high purity rare earth oxide and cobalt sulfate heptahydrate; realizes the recycling of electrolyte (raffinate) and avoids the discharge of wastewater. The whole process has the advantages of low acid and alkali consumption, low energy consumption, simple treatment process and remarkable industrialization.
The above examples are presented only to aid in understanding the core concept of the present invention; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present invention, the present description should not be construed as limiting the present invention in view of the above.
Claims (7)
1. A method for recovering rare earth and cobalt elements from rare earth permanent magnet mud-like waste, comprising at least the steps of:
(a) Placing the leaching anode, the oxidation anode and the cathode in electrolyte for electrolysis; rare earth permanent magnet mud-like waste is adsorbed on the leaching anode; leaching the anode to produce H by oxygen evolution reaction + Iron, cobalt and rare earth elements in the rare earth permanent magnet mud-shaped waste on the anode enter electrolyte in an ionic form; oxidizing the Fe in the anode to obtain Fe 2+ Oxidation to Fe 3+ The method comprises the steps of carrying out a first treatment on the surface of the OH produced by hydrogen evolution reaction at cathode - Fe is added to 3+ By Fe (OH) 3 Form precipitation of (c); a magnet for adsorbing rare earth permanent magnet mud-shaped waste is arranged on the leaching anode; the number of the cathodes is two, and the first cathode generates OH through hydrogen evolution reaction - Fe is added to 3+ By Fe (OH) 3 In the form of a precipitate, copper ion electrodeposition occurs at the second cathode; the leaching anode and the oxidation anode are made of ruthenium iridium titanium mesh materials;
(b) After stopping the electrolysis, the pH of the electrolyte is adjusted to make Fe 3+ By Fe (OH) 3 Removing iron by solid-liquid separation;
(c) Adding oxalic acid into the filtrate after solid-liquid separation in step (b), and obtaining rare earth oxalate and Co-containing solution through solid-liquid separation 2+ Is a solution of (a);
(d) To said step (c) Co-containing 2+ Adding an extractant into the solution of the catalyst to extract and separate cobalt, so as to obtain raffinate and a cobalt-loaded organic phase; and (3) reversely extracting the cobalt-loaded organic phase to obtain a purified cobalt solution.
2. The method for recovering rare earth and cobalt elements from rare earth permanent magnet sludge waste according to claim 1, wherein the pH of the electrolyte in said step (a) is 2.0 to 4.0.
3. The method for recovering rare earth and cobalt elements from rare earth permanent magnet sludge waste according to claim 1, wherein when the mass ratio of the leaching amount of the rare earth permanent magnet sludge waste to the electrolyte in the step (b) reaches 1:4-6, stopping the electrolysis of the leaching anode as a batch, continuing the operation of the oxidized anode for 0.5-2 h, and adding Fe 2+ Fully oxidized to Fe 3+ Then adjusting the pH of the electrolyte to lead Fe 3+ By Fe (OH) 3 Is precipitated in the form of (a).
4. The method for recovering rare earth and cobalt elements from rare earth permanent magnet sludge waste 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 according to claim 1, wherein the molar ratio of oxalic acid added in the step (c) to 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 according to claim 1, wherein said Co-containing material 2+ Adding extractant into the solution to extract and separate cobalt, wherein the extraction ratio O/A is 4-1:1.
7. The method for recovering rare earth and cobalt elements from rare earth permanent magnet mud-like waste material according to claim 1, wherein the rare earth permanent magnet alloy oil mud/grinding mud waste material is put into a degreasing tank before electrolysis, petroleum ether is added to remove greasy dirt in the waste material, and the waste material is dried and then non-magnetic impurities are removed through magnetic separation.
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| CN112941321A (en) * | 2021-01-26 | 2021-06-11 | 浙江大学衢州研究院 | Method for strengthening leaching reaction of neodymium iron boron magnet by combining electrochemical anodic oxidation with ionic flocculant |
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| "Selective Extraction of REEs from NdFeB Magnets by a Room-Temperature Electrolysis Pretreatment Step";Prakash Venkatesan 等;《ACS Sustainable Chemistry & Engineering》;20180525;正文第1-21页 * |
| "钕铁硼废料资源化回收利用研究进展";付利雯 等;《有色金属科学与工程》;20200229;第11卷(第1期);第92-96页 * |
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