CN110055433B - Method for extracting and recycling rare earth elements in neodymium iron boron waste material by using liquid metal bismuth - Google Patents
Method for extracting and recycling rare earth elements in neodymium iron boron waste material by using liquid metal bismuth Download PDFInfo
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- CN110055433B CN110055433B CN201910052446.1A CN201910052446A CN110055433B CN 110055433 B CN110055433 B CN 110055433B CN 201910052446 A CN201910052446 A CN 201910052446A CN 110055433 B CN110055433 B CN 110055433B
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- 229910052761 rare earth metal Inorganic materials 0.000 title claims abstract description 178
- 229910001172 neodymium magnet Inorganic materials 0.000 title claims abstract description 158
- QJVKUMXDEUEQLH-UHFFFAOYSA-N [B].[Fe].[Nd] Chemical compound [B].[Fe].[Nd] QJVKUMXDEUEQLH-UHFFFAOYSA-N 0.000 title claims abstract description 145
- 239000002699 waste material Substances 0.000 title claims abstract description 131
- 238000000034 method Methods 0.000 title claims abstract description 73
- 229910052797 bismuth Inorganic materials 0.000 title claims abstract description 61
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 title claims abstract description 52
- 229910001338 liquidmetal Inorganic materials 0.000 title claims abstract description 37
- 238000004064 recycling Methods 0.000 title abstract description 13
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 109
- 229910052751 metal Inorganic materials 0.000 claims abstract description 108
- 239000002184 metal Substances 0.000 claims abstract description 106
- 239000000956 alloy Substances 0.000 claims abstract description 49
- 239000007791 liquid phase Substances 0.000 claims abstract description 49
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 48
- 229910052779 Neodymium Inorganic materials 0.000 claims abstract description 37
- 229910052742 iron Inorganic materials 0.000 claims abstract description 35
- 239000000463 material Substances 0.000 claims abstract description 35
- 239000000155 melt Substances 0.000 claims abstract description 23
- -1 bismuth rare earth Chemical class 0.000 claims abstract description 21
- 238000010438 heat treatment Methods 0.000 claims abstract description 17
- 238000005191 phase separation Methods 0.000 claims abstract description 13
- 229910052796 boron Inorganic materials 0.000 claims abstract description 10
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims abstract description 8
- 238000002844 melting Methods 0.000 claims abstract description 8
- 230000008018 melting Effects 0.000 claims abstract description 8
- 150000002910 rare earth metals Chemical class 0.000 claims description 54
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- 229910052777 Praseodymium Inorganic materials 0.000 claims description 28
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- 239000007788 liquid Substances 0.000 claims description 22
- 239000000203 mixture Substances 0.000 claims description 20
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- ZDVYABSQRRRIOJ-UHFFFAOYSA-N boron;iron Chemical compound [Fe]#B ZDVYABSQRRRIOJ-UHFFFAOYSA-N 0.000 abstract description 6
- 150000002739 metals Chemical class 0.000 abstract description 6
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 abstract description 6
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- 238000000605 extraction Methods 0.000 description 10
- PLDDOISOJJCEMH-UHFFFAOYSA-N neodymium(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Nd+3].[Nd+3] PLDDOISOJJCEMH-UHFFFAOYSA-N 0.000 description 10
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 8
- 238000010586 diagram Methods 0.000 description 8
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- 239000003153 chemical reaction reagent Substances 0.000 description 4
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- 238000007711 solidification Methods 0.000 description 4
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- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
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- 238000003723 Smelting Methods 0.000 description 3
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- 239000002910 solid waste Substances 0.000 description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- PEFIIJCLFMFTEP-UHFFFAOYSA-N [Nd].[Mg] Chemical compound [Nd].[Mg] PEFIIJCLFMFTEP-UHFFFAOYSA-N 0.000 description 2
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- 238000005660 chlorination reaction Methods 0.000 description 2
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- 239000010941 cobalt Substances 0.000 description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 2
- KPLQYGBQNPPQGA-UHFFFAOYSA-N cobalt samarium Chemical compound [Co].[Sm] KPLQYGBQNPPQGA-UHFFFAOYSA-N 0.000 description 2
- JKWMSGQKBLHBQQ-UHFFFAOYSA-N diboron trioxide Chemical compound O=BOB=O JKWMSGQKBLHBQQ-UHFFFAOYSA-N 0.000 description 2
- 238000011978 dissolution method Methods 0.000 description 2
- KBQHZAAAGSGFKK-UHFFFAOYSA-N dysprosium atom Chemical compound [Dy] KBQHZAAAGSGFKK-UHFFFAOYSA-N 0.000 description 2
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- 238000010304 firing Methods 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 235000006408 oxalic acid Nutrition 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 2
- PUDIUYLPXJFUGB-UHFFFAOYSA-N praseodymium atom Chemical compound [Pr] PUDIUYLPXJFUGB-UHFFFAOYSA-N 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 229910000938 samarium–cobalt magnet Inorganic materials 0.000 description 2
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910052684 Cerium Inorganic materials 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- 229910052691 Erbium Inorganic materials 0.000 description 1
- 229910052688 Gadolinium Inorganic materials 0.000 description 1
- 229910052689 Holmium Inorganic materials 0.000 description 1
- 241000282414 Homo sapiens Species 0.000 description 1
- 241001465754 Metazoa Species 0.000 description 1
- 229910052772 Samarium Inorganic materials 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
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- 238000003916 acid precipitation Methods 0.000 description 1
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- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229960000892 attapulgite Drugs 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
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- ZMIGMASIKSOYAM-UHFFFAOYSA-N cerium Chemical compound [Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce] ZMIGMASIKSOYAM-UHFFFAOYSA-N 0.000 description 1
- 238000009388 chemical precipitation Methods 0.000 description 1
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- UYAHIZSMUZPPFV-UHFFFAOYSA-N erbium Chemical compound [Er] UYAHIZSMUZPPFV-UHFFFAOYSA-N 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- UIWYJDYFSGRHKR-UHFFFAOYSA-N gadolinium atom Chemical compound [Gd] UIWYJDYFSGRHKR-UHFFFAOYSA-N 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- KJZYNXUDTRRSPN-UHFFFAOYSA-N holmium atom Chemical compound [Ho] KJZYNXUDTRRSPN-UHFFFAOYSA-N 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 238000000462 isostatic pressing Methods 0.000 description 1
- 238000010902 jet-milling Methods 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 239000000696 magnetic material Substances 0.000 description 1
- 238000007885 magnetic separation Methods 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 238000010309 melting process Methods 0.000 description 1
- 229910052987 metal hydride Inorganic materials 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- CRLLGLJOPXYTLX-UHFFFAOYSA-N neodymium silver Chemical compound [Ag].[Nd] CRLLGLJOPXYTLX-UHFFFAOYSA-N 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 229910052625 palygorskite Inorganic materials 0.000 description 1
- 229910000027 potassium carbonate Inorganic materials 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001698 pyrogenic effect Effects 0.000 description 1
- 238000005057 refrigeration Methods 0.000 description 1
- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
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- GZCRRIHWUXGPOV-UHFFFAOYSA-N terbium atom Chemical compound [Tb] GZCRRIHWUXGPOV-UHFFFAOYSA-N 0.000 description 1
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- 229910052727 yttrium Inorganic materials 0.000 description 1
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B15/00—Other processes for the manufacture of iron from iron compounds
-
- 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
- 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
-
- 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)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Mechanical Engineering (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention belongs to the field of metal resource recycling, and particularly relates to a method for extracting and recycling rare earth elements in neodymium iron boron waste materials by using liquid metal bismuth. Firstly, melting metal bismuth in an induction heating furnace; adding the waste neodymium iron boron into liquid metal bismuth, heating to melt the neodymium iron boron waste, and performing liquid-liquid phase separation to form two immiscible solution phases rich in bismuth and iron; then, preserving heat to enable rare earth elements in the neodymium iron boron waste to be enriched in liquid metal bismuth to form a bismuth rare earth alloy melt, wherein the iron-rich liquid phase is an iron boron alloy melt; and finally, separating the two completely layered alloy melts (the upper layer is the iron-boron-rich alloy melt, and the lower layer is the bismuth-rare earth alloy melt). The Fe-B ferroboron alloy can be recycled for producing neodymium iron boron permanent magnet materials after being refined; the metals Bi, Nd and the like in the bismuth rare earth alloy are separated by vacuum evaporation. Under the environment-friendly condition, the rare earth elements such as neodymium in the neodymium iron boron are separated in one step, and the iron and boron elements are recycled.
Description
Technical Field
The invention belongs to the field of metal resource recycling, and particularly relates to a method for extracting and recycling rare earth elements in neodymium iron boron waste materials by using liquid metal bismuth.
Background
The rare earth elements have unique physical and chemical properties and are widely applied to development and innovation of science and technology, so that the global demand on rare earth metal resources is increased year by year. Especially in recent years, the dependence of new technologies on rare earth resources, which are dedicated to reducing energy consumption and developing renewable energy, has been remarkably enhanced. The rare earth elements are widely applied to new materials such as permanent magnet materials, luminescent materials, hydrogen storage alloys, electrode materials of nickel-metal hydride batteries, polishing and catalysts and the like. However, most rare earth elements are applied to the preparation of rare earth permanent magnetic materials. From the first generation rare earth permanent magnet samarium cobalt developed in 1967 to the third generation rare earth permanent magnet neodymium iron boron developed in 1983, the rare earth elements used therein are samarium, praseodymium, neodymium, terbium, dysprosium, lanthanum, cerium, gadolinium, holmium, erbium, yttrium, etc. The third generation neodymium iron boron rare earth permanent magnet material has the advantages of light weight, small volume, strong magnetism, extremely high magnetic energy, easily available raw materials, low price and the like, is developed extremely rapidly, is the permanent magnet material with the highest cost performance so far, and is praised as 'Magwang' in the magnetics world. It is widely used in hard disk drives, wind power generation, electric power steering, hybrid and electric vehicles, electric bicycles, electronic consumer products, household appliances, and the like. In addition, the neodymium iron boron permanent magnet material is also arranged on a lifter, magnetic separation and magnetic refrigeration equipment. The rare earth permanent magnet materials widely used at present mainly include sintered neodymium iron boron (accounting for 91.4%), bonded neodymium iron boron (accounting for 6.7%), hot-pressed/hot-deformed neodymium iron boron (accounting for 0.6%) and sintered samarium cobalt (accounting for 1.3%). In 2017, the yield of the global neodymium-iron-boron permanent magnet is nearly 20 ten thousand tons, wherein China accounts for about 85 percent.
The waste neodymium iron boron mainly comes from: firstly, waste materials generated in the process of preparing the neodymium iron boron materials and secondly, waste materials generated when the neodymium iron boron materials are finally invalid along with the use of devices. The production and preparation process of the rare earth neodymium iron boron permanent magnet material mainly comprises the following steps: the method comprises the steps of material preparation, alloy smelting, hydrogen crushing, jet milling, magnetic field orientation forming, isostatic pressing, oil stripping, sintering, machining and the like. Each process in the production process of the neodymium iron boron permanent magnet material can generate a certain amount of waste materials or waste products, and the method mainly comprises the following steps: raw material loss generated in the pretreatment process of raw materials, neodymium iron boron waste generated due to severe oxidation in the induction melting process, ultrafine powder generated in the powder production process, powder oxidized in the powder production process, neodymium iron boron blocky material oxidized in the sintering process, a large amount of leftover materials generated in the processing and forming process, unqualified products generated in the surface treatment process and the like. According to statistics, the utilization rate of raw materials is only about 70% in the production process of the neodymium iron boron rare earth permanent magnet, and about 30% of waste materials are generated. In addition, the neodymium iron boron rare earth permanent magnet material is widely applied to new technologies and products such as hard disk drives, wind driven generators, electric power steering, hybrid power and electric vehicles, electric bicycles, electronic consumer products, household appliances and the like. These products have an age and are out of date. For example, the voice coil motor has a lifetime of 8 years, the hybrid/electric vehicle has a lifetime of 15 years, the consumer motor has a lifetime of 15 years, the wind power motor has a lifetime of 20 years, and so on. The installed capacity of the Chinese wind power in 2017 exceeds 188GW, the installed capacity is 1.5MW, and about 1 ton of neodymium iron boron permanent magnet is needed. Since 2000 years, the installed capacity of wind power in China has increased year by year, and particularly, the installed capacity of wind power in China has rapidly increased in recent 10 years. The total amount of the rare earth neodymium iron boron permanent magnet which is scrapped globally in 2016 is 5-6 ten thousand tons, China accounts for more than 60%, and the scrapping amount is increased year by year. The content of rare earth elements such as praseodymium, neodymium, dysprosium and the like in the neodymium iron boron rare earth permanent magnet material is up to 25-30%, and the balance of the rare earth elements are mainly metal iron, cobalt, nickel, element boron and the like. If a large amount of waste neodymium iron boron rare earth permanent magnets cannot be efficiently and green recycled, a large amount of pollution sources and secondary pollution are generated, resource waste is caused, and the development of circular economy is contradicted. Therefore, the recovery of metal elements from the waste neodymium iron boron rare earth permanent magnet material is not only beneficial to ecological environment protection, but also can relieve the crisis of rare earth resources and promote resource recycling production, and has important significance to environmental protection and economic development.
At present, the recovery of the neodymium iron boron permanent magnet waste mainly comprises two treatment methods, namely a wet method and a fire method. The wet process mainly comprises 4 steps: dissolving the waste material with chemical reagent to distribute metal ion in the solution for leaching; ② separating the leaching solution from the residue; purifying and separating the leaching solution by ion exchange, solvent extraction or other chemical precipitation methods; and extracting the compound from the purified solution. Based on the wet recovery of rare earth, a sulfate double salt precipitation method, a sulfide precipitation method, a hydrochloric acid dissolution method, an oxalic acid precipitation method and the like are developed at home and abroad. The literature (Linhecheng, research on preparation of neodymium oxide, rare metals and hard alloy, 03:4-7,1997) reports that rare earth is recovered from neodymium-iron-boron waste by a sulfuric acid-double salt method and a neodymium oxide product is prepared. The literature (Chenyun brocade, recovery of rare earth and cobalt from waste neodymium iron boron slag by total extraction method 06:10-12, 2004) reports that neodymium iron boron waste is dissolved in hydrochloric acid by using hydrochloric acid total dissolution method, and iron and rare earth elements are separated by adjusting the pH value. The literature (Yi Xiao Wen et al, research on recovery of rare earth elements in neodymium iron boron waste by oxalate precipitation method, rare metals, 06: 1093-. In addition, the invention patent (a method for recovering and extracting rare earth oxide from neodymium iron boron waste, publication No. CN107012330A) discloses a method for recovering and extracting rare earth oxide from neodymium iron boron waste, which adopts the processes of crushing, burning, cleaning, acid dissolving, extracting and roasting to obtain the rare earth oxide. The invention patent (a method for recovering rare earth from neodymium iron boron waste, publication No. CN106319249A) discloses a method for recovering rare earth from neodymium iron boron waste, which is to dissolve neodymium iron boron waste by using hydrogen peroxide and oxidability and weak acidity, then to extract iron element in solution by using N503, then to extract rare earth element by using P507, and finally to precipitate corresponding rare earth ions by using oxalic acid and potassium carbonate respectively. The invention patent (method for recovering rare earth from neodymium iron boron waste, publication No. CN103146925A) discloses a method for recovering rare earth from neodymium iron boron waste, which comprises the steps of roasting, acid dissolution, separation, firing and the like, wherein filtrate is treated by adopting modified attapulgite and hydrogen peroxide, and rare earth oxide is obtained after processes of centrifugal deslagging, extraction separation, precipitation separation and the like. The invention patent (method for recovering rare earth elements from neodymium iron boron waste, publication number CN102011020A) discloses a method for recovering rare earth elements from neodymium iron boron waste, which comprises the following steps: mixing neodymium iron boron waste with water, grinding, oxidizing the ground neodymium iron boron, secondarily grinding an oxidation product, adding acid for leaching, performing solid-liquid separation, extracting for removing iron, chlorinating rare earth, extracting for separating rare earth, extracting for removing aluminum, precipitating, firing and the like.
The pyrogenic process is mainly divided into a glass slag method, an alloy method, a chlorination method, a selective oxidation method, a slag finance method and the like. In 2003, Saito et al used a glass-slag method to oxidize rare earth elements in neodymium-iron-boron waste materials into neodymium oxide by using boron oxide as an oxidizing agent, and the boron oxide is reduced into a boron simple substance and enters iron to form an iron-boron alloy. Uda used FeCl in 20022Is a chlorinating agent, and the rare earth elements in the neodymium iron boron waste material are treated at the temperature of 800 DEG CChloridized and then the rare earth chloride is recovered by adopting a vacuum distillation mode. Hua et al proposed to utilize MgCl in composite molten salt in 20142-KCl selective chlorination of rare earth elements, recovery of rare earths from neodymium iron boron wastes. Takeda et al, 2003 and 2004, propose to extract rare earth elements from neodymium iron boron solid wastes using magnesium or silver as an extractant. Distilling the obtained magnesium neodymium alloy to separate magnesium from neodymium in the magnesium neodymium alloy; for the obtained silver-neodymium alloy, the rare earth neodymium element is oxidized into solid neodymium oxide by adopting selective oxidation, and then the neodymium oxide and the molten metal silver are obtained by liquid/solid separation. However, it is obviously difficult to realize industrial production by using metallic silver. Okabe et al, 2018, proposed immersing solid neodymium-iron-boron waste in molten MgCl at 1000 deg.C2And (3) selectively chlorinating the rare earth elements for 3-12 hours, thereby extracting the rare earth elements from the neodymium iron boron solid waste. The method has long treatment time and high energy consumption.
Therefore, the method for recycling the rare earth in the neodymium iron boron waste needs to pretreat the neodymium iron boron waste, and has the problems of long process flow, high consumption of chemical reagents, high energy consumption, secondary pollution, difficult recycling of iron elements and the like.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide the method for extracting and recovering the rare earth elements in the neodymium iron boron waste by using the liquid metal bismuth, which has the advantages of short process flow, high efficiency, no need of caustic chemical reagents, zero emission, environmental friendliness and capability of solving the problems of comprehensive high-efficiency recovery and recycling of the neodymium iron boron waste including rare earth, iron and boron elements by combining the metallurgical characteristics of liquid-liquid phase separation and the selective distribution rule of multiple metal components in a liquid phase separation system.
The technical scheme of the invention is as follows:
a method for extracting and recovering rare earth elements in neodymium iron boron waste materials by using liquid metal bismuth comprises the following steps:
step 2, constructing a Fe-Bi liquid-liquid phase separation system by using the waste neodymium iron boron and the bismuth-rich extractant: the liquid state is rich in Fe + and the liquid state is rich in Bi;
step 3, placing the mixture of the waste neodymium iron boron and the bismuth-rich extractant in an alumina crucible for heating and melting, stirring the melt in the crucible to ensure that the liquid bismuth-rich extractant fully contacts the liquid neodymium iron boron melt, and extracting all rare earth elements in the waste neodymium iron boron into the bismuth-rich extractant melt step by step;
and 4, after the melt in the alumina crucible is kept warm, separating the Fe-rich melt at the upper layer from the Bi-rich melt at the lower layer.
According to the method for extracting and recovering the rare earth elements from the neodymium iron boron waste by using the liquid metal bismuth, the chemical composition of the recovered and treated waste neodymium iron boron in the step 1 mainly comprises transition metal elements, light rare earth elements and heavy rare earth elements.
According to the method for extracting and recovering the rare earth elements in the neodymium iron boron waste material by using the liquid metal bismuth, the transition metal elements are Fe, Co, Ni and Cu, the light rare earth elements are Nd and Pr, and the heavy rare earth elements are Dy or Tb.
The method for extracting and recovering the rare earth elements in the neodymium iron boron waste material by using the liquid metal bismuth comprises the following steps of 2: metal Bi having a purity of 99wt% or more; or a Bi-rich Bi alloy in which the Bi content is not less than 50 wt%.
The method for extracting and recovering the rare earth elements in the neodymium iron boron waste by using the liquid metal bismuth comprises the step 3 of mixing the waste neodymium iron boron with the bismuth-rich extractant, wherein the weight percentage of the metal Bi is 15-60%.
The method for extracting and recovering the rare earth elements in the neodymium iron boron waste by using the liquid metal bismuth comprises the step 3 of heating and melting the mixed ingredients of the waste neodymium iron boron and the bismuth-rich extractant at the temperature of 1200-1450 ℃.
The method for extracting and recovering the rare earth elements in the neodymium iron boron waste by the liquid metal bismuth comprises the step 3 of extracting and separating the rare earth elements in the waste neodymium iron boron by the liquid bismuth-rich extracting agent step by step, wherein the rare earth elements comprise light rare earth elements Nd and Pr and heavy rare earth elements Dy or Tb.
The method for extracting and recovering the rare earth elements from the neodymium iron boron waste by the liquid metal bismuth comprises the step 4, wherein the heat preservation temperature of a melt in an alumina crucible is 1350-1450 ℃, and the heat preservation time is 5-10 minutes.
In the method for extracting and recycling rare earth elements in neodymium iron boron waste materials by using liquid metal bismuth, in the upper-layer Fe-rich melt separated in the step 4, an alloy melt mainly composed of more than 98% by weight of transition metals Fe, Co, Ni and Cu and about 1-2% by weight of boron B elements is refined and then recycled to produce neodymium iron boron permanent magnet materials by using intermediate alloys.
In the method for extracting and recovering rare earth elements from neodymium iron boron waste materials by using liquid metal bismuth, in the lower-layer Bi-rich melt separated in the step 4, a Bi-RE bismuth rare earth alloy melt mainly composed of 40-70 wt% of metal Bi, 25-50 wt% of light rare earth elements Nd and Pr and 5-10 wt% of heavy rare earth elements Dy or Tb is separated successively by using a vacuum distillation technology to separate metal Bi and various rare earth metals Dy or Tb, Nd and Pr in the Bi-RE alloy; or based on the fact that the vapor pressure of metal Bi is higher than that of rare earth metal Dy or Tb, Nd and Pr at the same temperature, the metal Bi in the Bi-RE alloy is extracted and separated by adopting a vacuum distillation technology, and then the residual mixed rare earth contains Nd, Pr and Dy or Tb and is circularly used for producing the neodymium iron boron permanent magnet material by using the intermediate alloy.
The design idea of the invention is as follows:
based on the interaction principle between metal atoms, the larger the absolute value of the mixing heat between the two components is, the stronger the interaction is. Generally, a positive heat of mixing means that two element atoms repel each other, and a negative heat of mixing means that the element atoms attract each other. The heat of mixing any two of Fe, Nd and B is Δ H from the elements in the Nd-Fe-B alloyFe-Nd＝+1kJ/mol、ΔHFe-B＝-11kJ/mol、ΔHNd-BThis indicates that the elements Fe, Nd and B are mainly attracted to each other and have better affinity, which also means that the three elements are difficult to separate in the molten state of the ndfeb alloy. When the extractant metal Bi is introduced, the heat of mixing between them and Bi is Δ HFe-Bi＝+26kJ/mol、ΔHNd-Bi＝-55kJ/mol、ΔHB-Bi+46 kJ/mol. It can be seen that the Bi atoms and Fe/B atoms strongly repel each other, but the proBi atomThe atoms strongly attract Nd atoms. Therefore, elements such as rare earth Nd are diffused into the extractant Bi, and efficient green separation between the rare earth elements and iron boron is realized.
The invention has the advantages and beneficial effects that:
1. rare earth has the reputation of industrial vitamin, and is widely used for preparing rare earth permanent magnets, polishing materials, hydrogen storage materials, catalysis materials and the like, and neodymium iron boron rare earth permanent magnets are key materials of hard disk drives, motors, wind power generation, new energy automobiles and the like. However, during the preparation of these rare earth materials, such as neodymium iron boron permanent magnet materials, about 30% of waste materials such as sludge, scrap, etc. are generated. In addition, the products (such as computers, motors, automobiles and the like) containing the rare earth key materials have the service life and fail due to the expiration, so that a large amount of waste rare earth permanent magnets are generated. The annual scrappage of neodymium iron boron rare earth permanent magnets in China is 3-5 ten thousand tons, and the annual scrappage is increased year by year. The weight ratio of rare earth elements in the neodymium iron boron permanent magnet reaches about 25-35%, and the weight ratio of iron elements reaches about 65-75%. Therefore, the comprehensive and efficient separation and recovery of the neodymium iron boron waste materials have obvious economic benefits.
2. The invention is helpful to reduce the pressure of the waste on the ecological environment, and the rare earth permanent magnet material is widely applied to products such as electronic appliances, industrial motors, wind power generation, electric vehicles, automobiles and the like. With the continuous progress of scientific technology and the update of products, the products gradually become solid wastes. If the rare earth permanent magnet waste is not properly treated in the recovery process, the secondary pollution can bring great harm to the ecological environment, and great threat is brought to animals, plants and human beings. For example, the acidity and alkalinity of underground water and soil are seriously exceeded; a large amount of smoke is generated, and the atmosphere is seriously polluted. Therefore, the method has obvious environmental benefits by exploring a new technology and a new process for recycling the neodymium iron boron waste and carrying out comprehensive and efficient separation and recovery of the neodymium iron boron waste.
3. The method utilizes the liquid metal bismuth to extract and separate the rare earth metals in the waste neodymium iron boron, and enables various metal resources in the waste neodymium iron boron to be efficiently and environmentally recycled, so that the waste neodymium iron boron permanent magnet is recycled and reused. Therefore, under the environment-friendly condition, rare earth elements such as neodymium and the like in the waste neodymium iron boron are extracted in one step, and iron and boron elements are recycled.
Drawings
FIGS. 1(a) - (c) illustrate the use of rare earth element RE in a liquid phase separation system (L) according to the present invention1+L2) A principle diagram of selective distribution rule and high-efficiency separation and recovery of rare earth elements in neodymium iron boron waste.
Fig. 2(a) - (d) are schematic diagrams of the specific implementation process of recovering rare earth metals from neodymium iron boron waste by liquid metal bismuth extraction according to the present invention. In the figure, 1-a stopper rod, 2-an alumina crucible, 3-an induction coil, 4-an Fe-rich melt, 5-a Bi-rich melt, 6-a melt diversion port, and 7-a metal container.
FIG. 3 is a structural view of a microstructure of a lower Bi-RE alloy melt from which rare earth elements are extracted after cooling and solidification.
FIG. 4 is a schematic diagram of vacuum distillation separation of Bi-RE alloy, i.e., a diagram of relationship between the saturated vapor pressure logP (Pa) -temperature T (DEG C) of Bi and the rare earth elements Nd, Pr, and Dy.
FIG. 5 is a solidification structure morphology diagram of an upper layer Fe-B rich alloy melt after extraction separation of rare earth elements by liquid metal Bi from the neodymium iron boron waste melt.
Detailed Description
In the specific implementation process, the invention provides a method for efficiently separating and recovering rare earth elements in neodymium iron boron waste materials, and the extraction and separation of the rare earth metal elements from the neodymium iron boron waste materials are realized by utilizing the selective distribution rule of the rare earth elements in a liquid phase separation system. As shown in fig. 1(a) - (c), generally, there are three selective partitioning cases of the rare earth element RE in the liquid phase separation system: l with RE dissolved in liquid phase separation system1See fig. 1 (a); l with RE element dissolved in liquid phase separation system2See fig. 1 (b); ③ L of rare earth element RE not dissolved in liquid phase separation system1In (b) is also not dissolved in L2Rather, it is distributed between two separate liquid phases L1And L2See fig. 1 (c).
According to the principle, rare earth elements RE (Nd, Pr, Dy and the like) and transition metals TM (Fe, Co, Ni and the like) in the neodymium iron boron waste are separated efficiently, and almost all the rare earth elements are enriched in liquid metal Bi to form Bi-RE alloy melt. Then, the metal Bi and the rare earth element RE (Nd, Pr, Dy, etc.) in the Bi-RE alloy melt are separated by the existing industrial mature technology (such as a vacuum distillation method). Extracting rare earth elements in the neodymium iron boron waste material by adopting liquid metal Bi, and then separating and recycling the rare earth elements from the Bi-RE alloy melt; in addition, after the rare earth elements in the neodymium iron boron waste are extracted by liquid metal Bi, most of the remaining metals are transition metals TM (Fe, Co, Ni and the like) and a small amount of B elements. The Fe-B alloy is refined and then circularly used for producing the neodymium iron boron permanent magnet material by using the intermediate alloy. The method for extracting and recovering the rare earth metal from the waste permanent magnet material by the liquid metal bismuth has the advantages of short process flow, no need of using chemical reagents, short operation time period, low energy consumption, zero emission, no secondary pollution, high utilization rate of metal resource recovery and the like.
Firstly, melting metal bismuth in an induction heating furnace; adding the waste neodymium iron boron into liquid metal bismuth, heating to a certain temperature to melt the neodymium iron boron waste, and performing liquid-liquid phase separation to form a bismuth-rich and iron-rich immiscible solution phase; then, preserving the heat for a certain time to ensure that the rare earth elements in the neodymium iron boron waste are enriched in liquid metal bismuth to form a bismuth rare earth alloy melt, wherein the iron-rich liquid phase is an iron boron alloy melt; and finally, separating the two completely layered alloy melts (the upper layer is the iron-boron-rich alloy melt, and the lower layer is the bismuth-rare earth alloy melt). The Fe-B ferroboron alloy can be recycled for producing neodymium iron boron permanent magnet materials after being refined; the metals Bi, Nd and the like in the bismuth rare earth alloy are separated by vacuum evaporation. The method comprises the following steps:
step 2, preparing neodymium iron boron waste materials and metal bismuth according to a certain proportion to construct a Fe-Bi liquid-liquid phase separation system: the liquid state is rich in Fe + and the liquid state is rich in Bi;
step 3, placing the neodymium iron boron waste and the metal bismuth mixture in an alumina crucible for heating and melting, stirring the melt in the crucible to enable the liquid metal bismuth to fully contact the neodymium iron boron melt, and extracting and separating all rare earth elements in the neodymium iron boron waste into the metal bismuth melt in a one-step manner;
and 4, after the melt in the alumina crucible is kept warm for a period of time, the liquid Fe + rich Bi melt is layered up and down, and the Fe-B rich alloy melt on the upper layer is separated from the Bi-RE rich melt on the lower layer.
As shown in fig. 2(a) - (d), the specific implementation process of the present invention for recovering rare earth metals from waste neodymium iron boron by using liquid metal bismuth extraction is as follows:
fig. 2(a) is a diagram in which a mixture of neodymium iron boron waste and metal bismuth, which are prepared according to a certain proportion, is placed in an alumina crucible 2, a melt diversion port 6 is sealed and plugged by a plug rod 1, then an induction coil 3 of a vacuum intermediate frequency induction furnace is adopted for heating until the neodymium iron boron waste is melted, and liquid-liquid separation is carried out to form a Fe-rich melt 4 with a lower layer density and a Bi-rich melt 5 with a higher layer density. The rare earth element is almost completely extracted into the Bi-rich metal melt 5 due to the greater affinity between the rare earth RE atoms and the metal Bi atoms. After the temperature of the figure 2(b) is preserved for a certain time, the stopper rod 1 is lifted up slightly, and the Bi-rich metal melt 5 at the lower layer flows into a metal container 7 for containing the melt through a melt diversion port 6. FIG. 2(c) when the Bi-rich metal melt 5 in the lower layer is discharged from the crucible, the stopper rod 1 is reset to stop the melt guiding opening 6, and the metal container 7 containing the Bi-rich metal melt 5 is transferred for subsequent treatment. Fig. 2(d) lifts the stopper rod 1 slightly upward again, and the upper layer of Fe-rich metal melt 4 flows into another metal container through the melt guiding port 6.
Mixing neodymium iron boron waste materials and metal Bi according to the weight ratio of 1:1 to obtain a mixture, sealing and plugging a melt diversion port 6 by using a plug rod 1, then placing the mixture into an alumina crucible 2 of a vacuum intermediate frequency induction furnace, carrying out induction heating on the mixture under the argon protection environment until the neodymium iron boron rare earth permanent magnet waste materials (namely, neodymium iron boron waste materials) are completely melted, and stirring by using the alumina rod until no obvious unmelted solid exists in the crucible. Keeping the temperature for a period of time at a certain temperature, standing, allowing two liquid phases of the upper layer Fe-rich melt 4 and the lower layer Bi-rich melt 5 to flow out through a flow guide port, and cooling to obtain an Fe-B-rich alloy ingot and a Bi-RE-rich alloy ingot respectively.
As shown in fig. 3, the microstructure of the rare earth element-extracted lower Bi-rich metal melt after cooling and solidification. Chemical component analysis shows that the metal Bi in the Bi-rich metal melt accounts for 40-65% by mass, and the total mass of the rare earth elements Nd, Pr, Dy and the like accounts for 30-50%.
As shown in FIG. 4, a schematic diagram of vacuum distillation separation of Bi-RE alloy, i.e., a diagram of the relationship between the saturated vapor pressure and the temperature of metal Bi and rare earth elements Nd, Pr and Dy. Based on the different vapor pressures of Bi, Nd, Pr, Dy and other metal elements at the same temperature in the Bi-RE alloy melt, various metals are separated by a vacuum distillation method, and then high-purity metal simple substances are obtained; or based on the highest vapor pressure of metal Bi at the same temperature, the Bi element in the Bi-RE alloy is firstly separated by adopting a vacuum evaporation technology, and then the residual mixed rare earth (containing Nd, Dy, Pr and the like) is circularly used for producing the neodymium iron boron permanent magnet material by using the intermediate alloy.
As shown in fig. 5, the solidification structure morphology of the upper layer Fe-B-rich alloy melt after the rare earth elements of the neodymium iron boron scrap melt are extracted by the liquid metal Bi. Chemical composition analysis shows that the total mass percentage of transition metals such as Fe, Co, Ni and the like in the Fe-rich metal melt is more than 98%, and the total mass percentage of rare earth elements such as Nd, Pr and Dy is 0.1-1%. This shows that it is feasible to extract and recover the rare earth elements in the neodymium iron boron waste material by using the liquid metal Bi. The method can comprehensively recover light rare earth elements Nd, Pr and the like, heavy rare earth elements Dy and the like, transition metals Fe, Co, Ni and the like and boron B elements in the neodymium iron boron waste material in one step, so that the metal resource separation and extraction process is simplified, and the method has the characteristics of high efficiency, energy conservation, zero emission, environmental friendliness and the like, and has economic and environmental benefits.
Hereinafter, the present invention will be described in further detail by way of examples.
Example 1
Demagnetizing the rare earth strong magnet neodymium iron boron waste materials purchased in the market, cleaning stains on the surface of the rare earth strong magnet neodymium iron boron waste materials, and drying the rare earth strong magnet neodymium iron boron waste materials for later use. The neodymium iron boron waste and the metal Bi are prepared according to the weight ratio of 2:1, 1.33 kg of the neodymium iron boron waste and 0.67 kg of the metal Bi are weighed, and 2 kg of the mixture is calculated. And (3) plugging the melt diversion port of the alumina crucible by using an alumina plug rod in a sealing manner, then loading 2 kg of mixture into the alumina crucible of the medium-frequency induction melting furnace, carrying out induction heating on the mixture under the argon protection environment, and heating until the neodymium iron boron rare earth permanent magnet waste is melted until no obvious unmelted solid exists in the crucible when the alumina plug rod is used for stirring. Then, the melt in the crucible was left standing for 10 minutes at 1450 ℃. Liquid-liquid separation forms two liquid phases of a Fe-rich liquid phase and a Bi-rich liquid phase. Because the density of the Fe-rich liquid phase is less than that of the Bi-rich liquid phase, the Fe-rich liquid phase floats upwards under the action of gravity, and the Bi-rich liquid phase sinks to form a layered structure of the Fe-rich liquid phase and the Bi-rich liquid phase. And starting the stopper rod to enable the stopper rod to move upwards by 6-8 mm, wherein the lower-layer Bi-rich liquid melt flows out through the flow guide port, and the iron crucible is used for containing the Bi-rich alloy melt. And after the lower-layer Bi-rich liquid phase in the alumina crucible flows out from the flow guide port, the plug rod is started to reset, the flow guide port is plugged, and after another iron crucible container is replaced, the plug rod is started again, so that the residual Fe-rich melt in the alumina crucible is guided into the iron crucible from the flow guide port. And after the Fe-rich metal melt in the alumina crucible flows out completely, starting the plug rod to reset, plugging the flow guide port, adding the mixture of the next furnace of neodymium iron boron waste and metal Bi, and starting the next batch of circulating operation. And after the Fe-rich alloy melt and the Bi-rich alloy melt in the two iron crucibles are cooled and solidified, respectively sampling for analysis and detection.
The results showed that the weight percentage of rare earth elements (Nd, Pr, Dy) in the Bi-rich alloy ingot was 34.4%, the weight percentage of extracted metal Bi was 63.8%, the weight percentage of metal Fe was 1.65%, the weight percentage of metal Al was 0.09%, and the weight percentage of element Si was 0.06%. In the Fe-rich alloy ingot, the weight percentage of rare earth elements (Nd, Pr and Dy) is 0.78 percent, the weight percentage of extracted metal Bi is 1.01 percent, the weight percentage of metal Fe is 93.14 percent, the weight percentage of metal Al is 0.46 percent, the weight percentage of element Si is 0.34 percent, the weight percentage of metal Mn is 0.12 percent, the weight percentage of metal Ni is 2.19 percent, the weight percentage of metal Co is 1.83 percent, and the weight percentage of metal Cu is 0.13 percent.
Therefore, when the neodymium iron boron waste and the metal Bi are configured according to the weight ratio of 2:1, the heavy rare earth and the light rare earth in the neodymium iron boron waste are extracted by the liquid metal Bi in a short time, and the recovery rate of the rare earth elements reaches 95.6%. This example 1 demonstrates the validity of the principle of the present invention.
Example 2
Demagnetizing the rare earth strong magnet neodymium iron boron waste materials purchased in the market, cleaning stains on the surface of the rare earth strong magnet neodymium iron boron waste materials, and drying the rare earth strong magnet neodymium iron boron waste materials for later use. The neodymium iron boron waste and the metal Bi are prepared according to the weight ratio of 3:2, 1.33 kg of the neodymium iron boron waste and 0.87 kg of the metal Bi are weighed, and 2.2 kg of mixed materials are calculated. And (3) plugging the melt diversion port of the alumina crucible by using an alumina plug rod in a sealing manner, then loading 2.2 kg of mixture into the alumina crucible of the medium-frequency induction smelting furnace, carrying out induction heating on the mixture under the argon protection environment, and heating until the neodymium iron boron rare earth permanent magnet waste is melted until no obvious unmelted solid exists in the crucible when the alumina rod is used for stirring. Then, the melt in the crucible was left standing for 10 minutes at 1400 ℃. Liquid-liquid separation forms two liquid phases of a Fe-rich liquid phase and a Bi-rich liquid phase. Because the density of the Fe-rich liquid phase is less than that of the Bi-rich liquid phase, the Fe-rich liquid phase floats upwards under the action of gravity, and the Bi-rich liquid phase sinks to form a layered structure of the Fe-rich liquid phase and the Bi-rich liquid phase. And starting the stopper rod to enable the stopper rod to move upwards by 6-8 mm, wherein the lower-layer Bi-rich liquid melt flows out through the flow guide port, and the iron crucible is used for containing the Bi-rich alloy melt. And after the lower-layer Bi-rich liquid phase in the alumina crucible flows out from the flow guide port, the plug rod is started to reset, the flow guide port is plugged, and after another iron crucible container is replaced, the plug rod is started again, so that the residual Fe-rich melt in the alumina crucible is guided into the iron crucible from the flow guide port. And after the Fe-rich metal melt in the alumina crucible flows out completely, starting the plug rod to reset, plugging the flow guide port, adding the mixture of the next furnace of neodymium iron boron waste and metal Bi, and starting the next batch of circulating operation. And after the Fe-rich alloy melt and the Bi-rich alloy melt in the two iron crucibles are cooled and solidified, respectively sampling for analysis and detection.
The results showed that the Bi-rich alloy ingot contained 29.41% by weight of the rare earth elements (Nd, Pr, Dy), 69.08% by weight of the extracted metal Bi, 1.44% by weight of the metal Fe, 0.03% by weight of the metal Al, and 0.04% by weight of the element Si. In the Fe-rich alloy ingot, the weight percentage of rare earth elements (Nd, Pr and Dy) accounts for 0.45 percent, the weight percentage of extracted metal Bi accounts for 0.51 percent, the weight percentage of metal Fe accounts for 95.54 percent, the weight percentage of metal Al accounts for 0.32 percent, the weight percentage of element Si accounts for 0.22 percent, the weight percentage of metal Mn accounts for 0.12 percent, the weight percentage of metal Ni accounts for 1.52 percent, the weight percentage of metal Co accounts for 1.2 percent, and the weight percentage of metal Cu accounts for 0.12 percent.
It can be seen that, compared with example 1, when the same weight of the ndfeb scrap is mixed with different weight of the extracted metal Bi, the weight of the extracted metal Bi is increased, the content of the rare earth element in the extracted metal Bi is reduced, but the extraction of the rare earth element in the ndfeb scrap is more complete, the content of the extracted metal Bi in the final Fe-rich alloy ingot is less, the content of the metal Fe is increased, and the recovery rate of the rare earth element reaches 97.4%. This example 2 is mainly to reflect the effect of the addition of the amount of the extraction metal Bi in comparison with example 1 in terms of the weight of the added extraction metal.
Example 3
Demagnetizing the rare earth strong magnet neodymium iron boron waste materials purchased in the market, cleaning stains on the surface of the rare earth strong magnet neodymium iron boron waste materials, and drying the rare earth strong magnet neodymium iron boron waste materials for later use. The neodymium iron boron waste and the metal Bi are prepared according to the weight ratio of 3:2, 1.33 kg of the neodymium iron boron waste and 0.87 kg of the metal Bi are weighed, and 2.2 kg of mixed materials are calculated. And (3) plugging the melt diversion port of the alumina crucible by using an alumina plug rod in a sealing manner, then loading 2.2 kg of mixture into the alumina crucible of the medium-frequency induction smelting furnace, carrying out induction heating on the mixture under the argon protection environment, and heating until the neodymium iron boron rare earth permanent magnet waste is melted until no obvious unmelted solid exists in the crucible when the alumina rod is used for stirring. Then, the melt in the crucible was kept at 1400 ℃ and left to stand for 5 minutes. Liquid-liquid separation forms two liquid phases of a Fe-rich liquid phase and a Bi-rich liquid phase. Because the density of the Fe-rich liquid phase is less than that of the Bi-rich liquid phase, the Fe-rich liquid phase floats upwards under the action of gravity, and the Bi-rich liquid phase sinks to form a layered structure of the Fe-rich liquid phase and the Bi-rich liquid phase. And starting the stopper rod to enable the stopper rod to move upwards by 6-8 mm, wherein the lower-layer Bi-rich liquid melt flows out through the flow guide port, and the iron crucible is used for containing the Bi-rich alloy melt. And after the lower-layer Bi-rich liquid phase in the alumina crucible flows out from the flow guide port, the plug rod is started to reset, the flow guide port is plugged, and after another iron crucible container is replaced, the plug rod is started again, so that the residual Fe-rich melt in the alumina crucible is guided into the iron crucible from the flow guide port. And after the Fe-rich metal melt in the alumina crucible flows out completely, starting the plug rod to reset, plugging the flow guide port, adding the mixture of the next furnace of neodymium iron boron waste and metal Bi, and starting the next batch of circulating operation. And after the Fe-rich alloy melt and the Bi-rich alloy melt in the two iron crucibles are cooled and solidified, respectively sampling for analysis and detection.
The results showed that the Bi-rich alloy ingot contained 29.37% by weight of the rare earth elements (Nd, Pr, Dy), 68.97% by weight of the extracted metal Bi, 1.58% by weight of the metal Fe, 0.04% by weight of the metal Al, and 0.04% by weight of the element Si. In the Fe-rich alloy ingot, the weight percentage of rare earth elements (Nd, Pr and Dy) accounts for 0.46 percent, the weight percentage of extracted metal Bi accounts for 0.6 percent, the weight percentage of metal Fe accounts for 95.44 percent, the weight percentage of metal Al accounts for 0.31 percent, the weight percentage of element Si accounts for 0.23 percent, the weight percentage of metal Mn accounts for 0.12 percent, the weight percentage of metal Ni accounts for 1.53 percent, the weight percentage of metal Co accounts for 1.19 percent, and the weight percentage of metal Cu accounts for 0.12 percent.
It can be seen that, compared with example 2, the proportion and total weight of the neodymium iron boron and the extracted metal Bi are completely the same, except that the heat preservation and standing time is 5 minutes. From the detection and analysis results, the heat preservation and standing time is properly reduced, and the effect of extracting the rare earth elements in the neodymium iron boron waste material by the metal Bi is not greatly influenced. This indicates that the rare earth elements can be extracted by liquid metal Bi relatively quickly, and the Bi-rich liquid phase and the Fe-rich liquid phase can be layered completely in a relatively short time, and the recovery rate of the rare earth elements reaches about 97.1%. This example 3 is mainly compared with example 2 in terms of the holding time, which is significant for lower energy consumption.
Claims (5)
1. A method for extracting and recovering rare earth elements in neodymium iron boron waste materials by using liquid metal bismuth is characterized by comprising the following steps:
step 1, cleaning dirt on the surface of waste neodymium iron boron, and drying;
step 2, constructing a Fe-Bi liquid-liquid phase separation system by using the waste neodymium iron boron and the bismuth-rich extractant: the liquid state is rich in Fe + and the liquid state is rich in Bi;
step 3, placing the mixture of the waste neodymium iron boron and the bismuth-rich extractant in an alumina crucible for heating and melting, stirring the melt in the crucible to ensure that the liquid bismuth-rich extractant fully contacts the liquid neodymium iron boron melt, and extracting all rare earth elements in the waste neodymium iron boron into the bismuth-rich extractant melt step by step; step 3, in the mixed ingredient of the waste neodymium iron boron and the bismuth-rich extractant, the weight percentage content of metal Bi is 15-60%;
step 4, after the melt in the alumina crucible is insulated, separating the Fe-rich melt at the upper layer from the Bi-rich melt at the lower layer;
the chemical composition of the waste neodymium iron boron recycled and treated in the step 1 mainly comprises transition metal elements, light rare earth elements and heavy rare earth elements;
the transition metal elements are Fe, Co, Ni and Cu, the light rare earth elements are Nd and Pr, and the heavy rare earth elements are Dy or Tb;
step 3, heating and melting the mixed ingredients of the waste neodymium iron boron and the bismuth-rich extractant at 1200-1450 ℃;
step 4, keeping the temperature of the melt in the alumina crucible between 1350 ℃ and 1450 ℃ and keeping the temperature for 5 to 10 minutes;
4, in the upper-layer Fe-rich melt separated in the step 4, an alloy melt mainly composed of more than 98 wt% of transition metals Fe, Co, Ni and Cu and 1-2 wt% of boron B element;
in the lower-layer Bi-rich melt separated in the step 4, the Bi-RE bismuth rare earth alloy melt mainly comprises 40-70 wt% of metal Bi, 25-50 wt% of light rare earth elements Nd and Pr and 5-10 wt% of heavy rare earth elements Dy or Tb.
2. The method for extracting and recovering rare earth elements from neodymium iron boron waste materials by using liquid metal bismuth according to claim 1, wherein the bismuth-rich extractant adopted in the step 2 is as follows: metal Bi having a purity of 99wt% or more; or a Bi-rich Bi alloy in which the Bi content is not less than 50 wt%.
3. The method for extracting and recovering rare earth elements from neodymium iron boron waste materials by using liquid metal bismuth as claimed in claim 1, wherein the step 3 is to extract and separate the rare earth elements in the waste neodymium iron boron by using the liquid bismuth-rich extractant in one step, wherein the rare earth elements comprise light rare earth elements Nd and Pr and heavy rare earth elements Dy or Tb.
4. The method for extracting and recovering rare earth elements from neodymium iron boron waste materials by using liquid metal bismuth as claimed in claim 1, wherein the upper layer of Fe-rich melt separated in step 4 is refined and then recycled by using intermediate alloy to produce neodymium iron boron permanent magnet materials.
5. The method for extracting and recovering rare earth elements from neodymium iron boron waste materials by using liquid metal bismuth as claimed in claim 1, wherein the metal Bi and various rare earth metals Dy or Tb, Nd or Pr are separated from the metal Bi in the Bi-RE alloy by vacuum distillation technology in the lower Bi-rich melt separated in the step 4; or based on the fact that the vapor pressure of metal Bi is higher than that of rare earth metal Dy or Tb, Nd and Pr at the same temperature, the metal Bi in the Bi-RE alloy is extracted and separated by adopting a vacuum distillation technology, and then the residual mixed rare earth contains Nd, Pr and Dy or Tb and is circularly used for producing the neodymium iron boron permanent magnet material by using the intermediate alloy.
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| CN114427042B (en) * | 2022-01-28 | 2023-02-03 | 江苏南方永磁科技有限公司 | Draw separator of high-purity rare earth oxide from neodymium iron boron waste material |
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