CN115725867A - Method for extracting rare earth from fly ash - Google Patents
Method for extracting rare earth from fly ash Download PDFInfo
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- CN115725867A CN115725867A CN202211052836.7A CN202211052836A CN115725867A CN 115725867 A CN115725867 A CN 115725867A CN 202211052836 A CN202211052836 A CN 202211052836A CN 115725867 A CN115725867 A CN 115725867A
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- 229910052761 rare earth metal Inorganic materials 0.000 title claims abstract description 132
- 239000010881 fly ash Substances 0.000 title claims abstract description 78
- 150000002910 rare earth metals Chemical class 0.000 title claims abstract description 66
- 238000000034 method Methods 0.000 title claims abstract description 37
- 239000002893 slag Substances 0.000 claims abstract description 102
- 238000005406 washing Methods 0.000 claims abstract description 95
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 75
- 239000007788 liquid Substances 0.000 claims abstract description 74
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims abstract description 54
- 239000003792 electrolyte Substances 0.000 claims abstract description 37
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 36
- -1 rare earth chloride Chemical class 0.000 claims abstract description 36
- 238000005868 electrolysis reaction Methods 0.000 claims abstract description 32
- 239000001103 potassium chloride Substances 0.000 claims abstract description 27
- 235000011164 potassium chloride Nutrition 0.000 claims abstract description 27
- 238000002156 mixing Methods 0.000 claims abstract description 20
- 238000004537 pulping Methods 0.000 claims abstract description 14
- 229910052751 metal Inorganic materials 0.000 claims abstract description 11
- 239000002184 metal Substances 0.000 claims abstract description 11
- 230000005484 gravity Effects 0.000 claims abstract description 9
- 150000002739 metals Chemical class 0.000 claims abstract description 8
- 238000000926 separation method Methods 0.000 claims abstract description 7
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 42
- 239000001569 carbon dioxide Substances 0.000 claims description 21
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 21
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 15
- 239000010439 graphite Substances 0.000 claims description 15
- 229910002804 graphite Inorganic materials 0.000 claims description 15
- 238000006243 chemical reaction Methods 0.000 claims description 14
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 9
- 238000001704 evaporation Methods 0.000 claims description 9
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 6
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 6
- 239000011575 calcium Substances 0.000 claims description 6
- 229910052791 calcium Inorganic materials 0.000 claims description 6
- 238000002386 leaching Methods 0.000 claims description 5
- 230000005684 electric field Effects 0.000 claims description 4
- 229910001385 heavy metal Inorganic materials 0.000 claims description 4
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 3
- 239000002738 chelating agent Substances 0.000 claims description 3
- 238000001816 cooling Methods 0.000 claims description 3
- 239000012535 impurity Substances 0.000 claims description 3
- 229910001338 liquidmetal Inorganic materials 0.000 claims description 3
- 229910052749 magnesium Inorganic materials 0.000 claims description 3
- 239000011777 magnesium Substances 0.000 claims description 3
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 2
- 238000000605 extraction Methods 0.000 abstract description 6
- 238000011282 treatment Methods 0.000 abstract description 3
- 229910052750 molybdenum Inorganic materials 0.000 description 6
- 239000011733 molybdenum Substances 0.000 description 6
- 239000002002 slurry Substances 0.000 description 6
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 4
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 4
- 239000011133 lead Substances 0.000 description 4
- 238000004064 recycling Methods 0.000 description 4
- 229910052725 zinc Inorganic materials 0.000 description 4
- 239000011701 zinc Substances 0.000 description 4
- ZKQDCIXGCQPQNV-UHFFFAOYSA-N Calcium hypochlorite Chemical compound [Ca+2].Cl[O-].Cl[O-] ZKQDCIXGCQPQNV-UHFFFAOYSA-N 0.000 description 3
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- NKWPZUCBCARRDP-UHFFFAOYSA-L calcium bicarbonate Chemical compound [Ca+2].OC([O-])=O.OC([O-])=O NKWPZUCBCARRDP-UHFFFAOYSA-L 0.000 description 3
- 229910000020 calcium bicarbonate Inorganic materials 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 229910052684 Cerium Inorganic materials 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 229910000019 calcium carbonate Inorganic materials 0.000 description 2
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 2
- 239000000920 calcium hydroxide Substances 0.000 description 2
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 2
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 2
- 239000000292 calcium oxide Substances 0.000 description 2
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 235000010755 mineral Nutrition 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 229910052692 Dysprosium Inorganic materials 0.000 description 1
- 229910052691 Erbium Inorganic materials 0.000 description 1
- 229910052693 Europium Inorganic materials 0.000 description 1
- 229910052688 Gadolinium Inorganic materials 0.000 description 1
- 229910052689 Holmium Inorganic materials 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910052765 Lutetium Inorganic materials 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 229910052773 Promethium Inorganic materials 0.000 description 1
- 229910052772 Samarium Inorganic materials 0.000 description 1
- 229910052771 Terbium Inorganic materials 0.000 description 1
- 229910052775 Thulium Inorganic materials 0.000 description 1
- 229910052769 Ytterbium Inorganic materials 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000007844 bleaching agent Substances 0.000 description 1
- 239000010882 bottom ash Substances 0.000 description 1
- ZFXVRMSLJDYJCH-UHFFFAOYSA-N calcium magnesium Chemical compound [Mg].[Ca] ZFXVRMSLJDYJCH-UHFFFAOYSA-N 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 1
- 238000003889 chemical engineering Methods 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- KBQHZAAAGSGFKK-UHFFFAOYSA-N dysprosium atom Chemical compound [Dy] KBQHZAAAGSGFKK-UHFFFAOYSA-N 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- UYAHIZSMUZPPFV-UHFFFAOYSA-N erbium Chemical compound [Er] UYAHIZSMUZPPFV-UHFFFAOYSA-N 0.000 description 1
- OGPBJKLSAFTDLK-UHFFFAOYSA-N europium atom Chemical compound [Eu] OGPBJKLSAFTDLK-UHFFFAOYSA-N 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- UIWYJDYFSGRHKR-UHFFFAOYSA-N gadolinium atom Chemical compound [Gd] UIWYJDYFSGRHKR-UHFFFAOYSA-N 0.000 description 1
- KJZYNXUDTRRSPN-UHFFFAOYSA-N holmium atom Chemical compound [Ho] KJZYNXUDTRRSPN-UHFFFAOYSA-N 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 238000009854 hydrometallurgy Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052747 lanthanoid Inorganic materials 0.000 description 1
- 150000002602 lanthanoids Chemical class 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
- 238000004020 luminiscence type Methods 0.000 description 1
- OHSVLFRHMCKCQY-UHFFFAOYSA-N lutetium atom Chemical compound [Lu] OHSVLFRHMCKCQY-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000008204 material by function Substances 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- LPUQAYUQRXPFSQ-DFWYDOINSA-M monosodium L-glutamate Chemical compound [Na+].[O-]C(=O)[C@@H](N)CCC(O)=O LPUQAYUQRXPFSQ-DFWYDOINSA-M 0.000 description 1
- 239000004223 monosodium glutamate Substances 0.000 description 1
- 235000013923 monosodium glutamate Nutrition 0.000 description 1
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 description 1
- PUDIUYLPXJFUGB-UHFFFAOYSA-N praseodymium atom Chemical compound [Pr] PUDIUYLPXJFUGB-UHFFFAOYSA-N 0.000 description 1
- VQMWBBYLQSCNPO-UHFFFAOYSA-N promethium atom Chemical compound [Pm] VQMWBBYLQSCNPO-UHFFFAOYSA-N 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000009853 pyrometallurgy Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 description 1
- 229910052706 scandium Inorganic materials 0.000 description 1
- SIXSYDAISGFNSX-UHFFFAOYSA-N scandium atom Chemical compound [Sc] SIXSYDAISGFNSX-UHFFFAOYSA-N 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- GZCRRIHWUXGPOV-UHFFFAOYSA-N terbium atom Chemical compound [Tb] GZCRRIHWUXGPOV-UHFFFAOYSA-N 0.000 description 1
- FRNOGLGSGLTDKL-UHFFFAOYSA-N thulium atom Chemical compound [Tm] FRNOGLGSGLTDKL-UHFFFAOYSA-N 0.000 description 1
- NAWDYIZEMPQZHO-UHFFFAOYSA-N ytterbium Chemical compound [Yb] NAWDYIZEMPQZHO-UHFFFAOYSA-N 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Processing Of Solid Wastes (AREA)
Abstract
The invention discloses a method for extracting rare earth from fly ash, which comprises the following steps: pulping fly ash and water according to a solid-to-liquid ratio of a preset proportion, and then washing to obtain fly ash washing liquid and washing slag respectively; decalcification treatment is carried out on the washing slag to obtain decalcification slag, and other valuable metals are recovered by gravity separation on the decalcification slag to obtain rare earth slag; the rare earth slag is diluted and dissolved in concentrated hydrochloric acid according to a solid-to-liquid ratio of a preset proportion, and then is evaporated to dryness to obtain rare earth chloride; and mixing the rare earth chloride and potassium chloride according to a preset proportion to form electrolyte required by electrolysis, and electrolyzing the electrolyte to obtain the rare earth element. The invention realizes the extraction of the rare earth in the fly ash.
Description
Technical Field
The invention relates to the technical field of chemical engineering, in particular to a method for extracting rare earth from fly ash.
Background
Rare earth elements include 17 elements of lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), scandium (Sc) and yttrium (Y) in lanthanide elements, and rare earth is a precious strategic resource, is called "industrial monosodium glutamate" and is a parent of new materials, and is widely applied to the fields of advanced science and technology and military industry.
According to introduction of the ministry of industry and informatization, at present, functional materials such as rare earth permanent magnet, luminescence, hydrogen storage, catalysis and the like are indispensable raw materials for high and new technology industries such as advanced equipment manufacturing industry, new energy sources, emerging industries and the like, and are widely applied to electronics, petrochemical industry, metallurgy, machinery, new energy sources, light industry, environmental protection, agriculture and the like. Therefore, how to separate and extract the rare earth elements becomes important.
At present, most of rare earth elements are smelted from rare earth ores, for example, rare earth is separated and extracted from rare earth concentrate by means of hydrometallurgy and pyrometallurgy, however, besides rare earth ore and other rare earth element-rich ores, there are also a large amount of substances capable of extracting rare earth elements, for example, fly ash and the like, which also contain a large amount of rare earth elements, and therefore, a method for extracting rare earth from fly ash is urgently needed to be proposed to extract rare earth elements in fly ash and realize resource recycling.
Disclosure of Invention
In view of this, the present invention provides a method for extracting rare earth from fly ash, which aims to extract rare earth from fly ash and realize resource recycling.
The embodiment of the invention is realized as follows:
a method of extracting rare earths from fly ash, the method comprising:
pulping fly ash and water according to a solid-to-liquid ratio of a preset proportion, and then washing to obtain fly ash washing liquid and washing slag respectively;
decalcification treatment is carried out on the washing slag to obtain decalcification slag, and other valuable metals are recovered by gravity separation on the decalcification slag to obtain rare earth slag;
the rare earth slag is diluted and dissolved in concentrated hydrochloric acid according to a solid-to-liquid ratio of a preset proportion, and then is evaporated to dryness to obtain rare earth chloride;
and mixing the rare earth chloride and potassium chloride according to a preset proportion to form electrolyte required by electrolysis, and electrolyzing the electrolyte to obtain the rare earth element.
Further, in the method for extracting rare earth from fly ash, the step of mixing the rare earth chloride and potassium chloride according to a preset ratio to form an electrolyte required for electrolysis, and the step of electrolyzing the electrolyte to obtain rare earth elements includes:
mixing potassium chloride in a molten state and anhydrous rare earth chloride according to a preset proportion to form an electrolyte, taking a graphite crucible as an anode and a molybdenum rod and liquid metal as a cathode, and electrolyzing the electrolyte under the action of a direct current electric field to obtain rare earth elements.
Further, the method for extracting the rare earth from the fly ash is characterized in that the electrolysis temperature is 620-900 ℃.
Further, in the method for extracting rare earth from fly ash, the fly ash and water are slurried according to a solid-to-liquid ratio of a preset proportion, and then are washed with water to obtain fly ash washing liquid and washing slag respectively, the steps of:
the solid-to-liquid ratio of fly ash to water is 1:6.
Further, in the method for extracting rare earth from fly ash, the rare earth slag is diluted in concentrated hydrochloric acid according to a solid-to-liquid ratio of a preset proportion, and then is evaporated to dryness to obtain rare earth chloride:
the solid-to-liquid ratio of the rare earth slag to the concentrated hydrochloric acid is 2-5:1.
Further, in the method for extracting rare earth from fly ash, the rare earth chloride and potassium chloride are mixed according to a preset ratio to form electrolyte required by electrolysis, and the step of electrolyzing the electrolyte to obtain rare earth elements comprises:
the mixing ratio of the rare earth chloride and the potassium chloride is 1/3-3:1.
Further, the method for extracting rare earth from fly ash, wherein the steps of pulping fly ash and water according to a solid-to-liquid ratio of a preset proportion, and then washing with water to obtain fly ash washing liquid and washing slag respectively, further comprise:
and adding a chelating agent into the water washing liquid to remove heavy metals, adding sodium carbonate to remove calcium and magnesium impurities, and finally cooling and crystallizing to obtain the potassium chloride.
Further, in the method for extracting rare earth from fly ash, the step of decalcifying the washed slag to obtain decalcified slag and the step of reselecting the decalcified slag to recover other valuable metals to obtain rare earth slag comprises:
and leaching the washing slag under high pressure by using carbon dioxide to decalcify the washing slag to obtain decalcified slag.
Further, in the method for extracting rare earth from fly ash, the step of leaching the washing slag with carbon dioxide under high pressure to decalcify the washing slag to obtain the decalcified slag comprises:
uniformly mixing the washing slag and water according to a preset solid-liquid ratio, placing the mixture into a high-pressure reaction kettle, and introducing excessive carbon dioxide into the reaction kettle to obtain decalcified slag;
wherein the solid-liquid ratio of the washing slag to water is 1.
Further, the method for extracting rare earth from fly ash comprises the following steps of pulping fly ash and water according to a solid-to-liquid ratio of a preset proportion, and then washing with water to obtain fly ash washing liquid and washing slag respectively:
pulping the fly ash and water according to a solid-liquid ratio of a preset proportion, introducing carbon dioxide to adjust the pH value to 6-8, and washing to obtain fly ash water washing liquid and water washing slag respectively.
The method comprises the steps of pulping the fly ash, then washing with water to obtain the washing slag enriched with the rare earth elements, decalcifying, reselecting and recycling the washing slag to obtain the rare earth slag, then fusing and evaporating the rare earth slag and concentrated hydrochloric acid to obtain rare earth chloride, and finally electrolyzing the rare earth chloride and potassium chloride to form electrolyte to obtain the rare earth elements, so that the extraction of the rare earth in the fly ash is realized, and the resource recycling is realized.
Drawings
FIG. 1 is a flow chart of a method for extracting rare earth from fly ash according to an embodiment of the present invention.
The following detailed description will further illustrate the invention in conjunction with the above-described figures.
Detailed Description
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
Further, as used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. In the detailed description and claims, a list of items connected by the term "one of" may mean any of the listed items. For example, if items a and B are listed, the phrase "one of a and B" means a alone or B alone. In another example, if items A, B and C are listed, the phrase "A, B and one of C" means a only; only B; or only C. Item a may comprise a single element or multiple elements. Item B may comprise a single element or multiple elements. Item C may comprise a single element or multiple elements. In the detailed description and claims, a list of items linked by the term "at least one of," "at least one of," or other similar terms may mean any combination of the listed items. For example, if items a and B are listed, the phrase "at least one of a and B" or "at least one of a or B" means a only; only B; or A and B. In another example, if items A, B and C are listed, the phrase "at least one of A, B and C" or "at least one of A, B or C" means a only; or only B; only C; a and B (excluding C); a and C (excluding B); b and C (excluding A); or A, B and all of C. Item a may comprise a single element or multiple elements. Item B may comprise a single element or multiple elements. Item C may comprise a single element or multiple elements.
The invention provides a method for extracting rare earth from fly ash, aiming at solving the problem that no method capable of extracting rare earth from fly ash exists at present, wherein the method comprises the following steps:
and S10, pulping the fly ash and water according to a solid-to-liquid ratio of a preset proportion, and then washing to respectively obtain fly ash washing liquid and washing slag.
The fly ash comprises but is not limited to a captured object captured by a flue gas purification system of a household garbage incineration facility, bottom ash settled at the bottom of a flue and a chimney, specifically, the fly ash and water are pulped according to a solid-liquid ratio of a preset proportion, then carbon dioxide is introduced to adjust the pH value to 6-8, and fly ash water washing liquid and water washing slag are respectively obtained by water washing, wherein in specific implementation, the solid-liquid ratio of the fly ash and the water is 1:6, and the water washing liquid mainly contains sodium chloride, potassium chloride, a small amount of calcium magnesium, heavy metal ions and the like.
It should be noted that the rare earth elements are distributed in the fly ash in a dispersed manner, and the rare earth elements in the fly ash can be enriched after washing with water, so that the extraction is facilitated.
And S11, decalcifying the washing slag to obtain decalcified slag, and reselecting the decalcified slag to recover other valuable metals to obtain rare earth slag.
Specifically, decalcification is carried out on the washing slag by adopting carbon dioxide high-pressure leaching, excessive carbon dioxide converts calcium in the slag into calcium bicarbonate to enter aqueous solution, so as to obtain decalcification slag, and the decalcification slag mainly contains part of enriched valuable metals and rare earth metals and can be recycled; wherein the solid-liquid ratio of the washing slag to water is 1.
The method is characterized in that valuable metals mainly comprise lead and zinc, lead and zinc metal slag is recovered by adopting a gravity separation method, the gravity separation method is a method for separating according to different mineral specific gravities and different sedimentation speeds of the mineral specific gravities in a medium, the lead and the zinc have large mass difference, and the process is simple and convenient to select.
And S12, diluting and dissolving the rare earth slag in concentrated hydrochloric acid according to a solid-to-liquid ratio of a preset proportion, and then evaporating to obtain rare earth chloride.
In particular, it is preferable that the concentration of concentrated hydrochloric acid is 36 to 38% and the solid-to-liquid ratio of the rare earth slag to the concentrated hydrochloric acid is 2 to 5:1, for example, 2:1, 3:1, 4:1 and 5:1.
And S13, mixing the rare earth chloride and potassium chloride according to a preset ratio to form electrolyte required by electrolysis, and electrolyzing the electrolyte to obtain the rare earth element.
Specifically, potassium chloride in a molten state and anhydrous rare earth chloride are mixed according to a preset proportion to form electrolyte, a graphite crucible is used as an anode, a molybdenum rod and liquid metal are used as a cathode, the electrolyte is electrolyzed under the action of a direct current electric field to obtain rare earth elements, and more specifically, re of the electrolyte is obtained under the action of the electric field in the molten state 3+ Cations migrate to the cathode and anions migrate to the anode. When the electrolytic voltage reaches ReCl 3 At decomposition voltage of (2), re on the cathode 3+ A reduction reaction occurs to accept electrons to form the metal. The chemical reaction formula is as follows:
anodic reaction 2C1 - -2e→Cl 2 ↑
Cathode reaction of Re 3+ (Ce 3+ 、La 3+ 、Pr 3+ ) +3e → Re (Ce, la, pr) ↓, wherein, the mixing ratio of the rare earth chloride and the potassium chloride is 1/3 to 3:1, for example, 1/3: 1. 1:1 and 3:1, and the electrolysis temperature is 620 to 900 ℃, for example, 620, 700, 800, and 900 ℃.
In addition, in some embodiments of the present invention, the steps of pulping the fly ash and water according to a solid-to-liquid ratio of a preset ratio, and then washing with water to obtain a fly ash washing liquid and washing slag respectively further include:
and adding a chelating agent into the water washing liquid to remove heavy metals, then adding sodium carbonate to remove calcium and magnesium impurities, and finally cooling and crystallizing to obtain the potassium chloride.
The water washing liquid is subjected to a series of treatments to obtain potassium chloride required by rare earth electrolysis, so that reasonable utilization of resources is realized.
In addition, the remaining mixed salt solution is mainly sodium salt, and sodium hydroxide and chlorine gas can be obtained by electrolysis. The washing slag is leached under high pressure by carbon dioxide, the excessive carbon dioxide converts calcium in the slag into calcium bicarbonate to enter into water solution, the calcium bicarbonate is easy to decompose at normal temperature to obtain calcium carbonate solid, the calcium carbonate is calcined to obtain calcium oxide and carbon dioxide, and the calcium oxide is added with water to obtain calcium hydroxide. Chlorine gas obtained by electrolysis in the water washing solution is introduced into a calcium hydroxide water solution to generate calcium hypochlorite, the calcium hypochlorite is the main component of the bleaching powder, and the process recycles calcium in the fly ash and solves the problem of chlorine gas discharge.
In order to facilitate an understanding of the invention, several embodiments of the invention are set forth below. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Example 1
Adding water into fly ash to prepare slurry according to the solid-to-liquid ratio of 1:6, introducing carbon dioxide to adjust the pH value to 6, and washing with water to obtain water washing liquid and water washing slag;
placing the washing slag and water in a high-pressure reaction kettle according to a solid-to-liquid ratio of 1;
dissolving the rare earth slag in concentrated hydrochloric acid according to a solid-to-liquid ratio of 2:1, and then evaporating to obtain rare earth chloride;
mixing rare earth chloride and potassium chloride according to the proportion of 1/3:1 to form electrolyte, wherein the electrolysis equipment adopts a graphite electrolysis bath, the anode is graphite, and the cathode is molybdenum. The electrolysis temperature was controlled at 620 ℃. The electrolyte is electrolyzed to obtain the rare earth element.
Example 2
Adding water into fly ash to prepare slurry according to the solid-to-liquid ratio of 1:6, introducing carbon dioxide to adjust the pH value to 7, and washing with water to obtain water washing liquid and water washing slag;
placing the washing slag and water in a high-pressure reaction kettle according to a solid-to-liquid ratio of 1;
dissolving the rare earth slag in concentrated hydrochloric acid according to a solid-to-liquid ratio of 3:1, and then evaporating to obtain rare earth chloride;
mixing rare earth chloride and potassium chloride according to a proportion of 1:1 to form electrolyte, wherein the electrolysis equipment adopts a graphite electrolysis bath, the anode is graphite, and the cathode is molybdenum. The electrolysis temperature was controlled at 700 ℃. The electrolyte is electrolyzed to obtain the rare earth element.
Example 3
Adding water into fly ash to prepare slurry according to the solid-to-liquid ratio of 1:6, introducing carbon dioxide to adjust the pH value to 8, and washing with water to obtain water washing liquid and water washing slag;
placing the washing slag and water in a high-pressure reaction kettle according to a solid-to-liquid ratio of 1;
dissolving the rare earth slag in concentrated hydrochloric acid according to a solid-to-liquid ratio of 4:1, and then evaporating to obtain rare earth chloride;
mixing rare earth chloride and potassium chloride according to a proportion of 2:1 to form electrolyte, wherein the electrolysis equipment adopts a graphite electrolysis bath, the anode is graphite, and the cathode is molybdenum. The temperature of electrolysis was controlled at 750 ℃. The electrolyte is electrolyzed to obtain the rare earth element.
Example 4
Adding water into fly ash to prepare slurry according to the solid-to-liquid ratio of 1:6, introducing carbon dioxide to adjust the pH value to 6, and washing with water to obtain water washing liquid and water washing slag;
placing the washing slag and water in a high-pressure reaction kettle according to a solid-to-liquid ratio of 1;
dissolving the rare earth slag in concentrated hydrochloric acid according to a solid-to-liquid ratio of 5:1, and then evaporating to obtain rare earth chloride;
mixing rare earth chloride and potassium chloride according to a proportion of 3:1 to form electrolyte, wherein the electrolysis equipment adopts a graphite electrolysis bath, the anode is graphite, and the cathode is molybdenum. The temperature of the electrolysis was controlled at 800 ℃. The electrolyte is electrolyzed to obtain the rare earth element.
Example 5
Adding water into fly ash to prepare slurry according to the solid-to-liquid ratio of 1:6, introducing carbon dioxide to adjust the pH value to 7, and washing with water to obtain water washing liquid and water washing slag;
placing the washing slag and water in a high-pressure reaction kettle according to a solid-to-liquid ratio of 1;
dissolving the rare earth slag in concentrated hydrochloric acid according to a solid-to-liquid ratio of 4:1, and then evaporating to obtain rare earth chloride;
mixing rare earth chloride and potassium chloride according to a proportion of 3:1 to form electrolyte, wherein the electrolysis equipment adopts a graphite electrolysis bath, the anode is graphite, and the cathode is molybdenum. The temperature of the electrolysis is controlled to be 850 ℃. The electrolyte is electrolyzed to obtain the rare earth element.
Example 6
Adding water into fly ash to prepare slurry according to the solid-to-liquid ratio of 1:6, introducing carbon dioxide to adjust the pH value to 7, and washing with water to obtain water washing liquid and water washing slag;
placing the washing slag and water in a high-pressure reaction kettle according to a solid-to-liquid ratio of 1:20, introducing excessive carbon dioxide, reacting at normal temperature for 3h under the pressure of 1.5MPa in the reaction kettle to obtain decalcified slag, and recovering lead and zinc metal slag from the decalcified slag by adopting a gravity separation mode;
dissolving the rare earth slag in concentrated hydrochloric acid according to a solid-to-liquid ratio of 4:1, and then evaporating to obtain rare earth chloride;
mixing rare earth chloride and potassium chloride according to a proportion of 2:1 to form electrolyte, wherein the electrolysis equipment adopts a graphite electrolysis bath, the anode is graphite, and the cathode is molybdenum. The temperature of the electrolysis was controlled at 900 ℃. The electrolyte is electrolyzed to obtain the rare earth element.
Referring to Table 1 below, the parameters for the above examples 1-6 of the present invention are shown in the following table:
TABLE 1
In practical applications, the extraction rates of the corresponding extracted rare earths of the above embodiments 1-6 of the present invention are respectively utilized to perform tests, and the test data are shown in the following table 2
TABLE 2
| Categories | Rare earth extraction ratio (%) |
| Example 1 | 83.5％ |
| Example 2 | 87.2％ |
| Example 3 | 90.2％ |
| Example 4 | 92.8％ |
| Example 5 | 93.4％ |
| Example 6 | 94.1％ |
In summary, it can be seen from the data in tables 1 and 2 that the present invention achieves extraction of rare earth from fly ash by pulping fly ash, then washing with water to obtain rare earth-enriched water-washed slag, then decalcifying, gravity separation and recovery of the water-washed slag to obtain rare earth slag, then fusing the rare earth slag and concentrated hydrochloric acid to dryness to obtain rare earth chloride, and finally forming an electrolyte from the rare earth chloride and potassium chloride to electrolyze to obtain rare earth elements, thereby achieving recovery and utilization of resources.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is specific and detailed, but not to be understood as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A method for extracting rare earth from fly ash, the method comprising:
pulping fly ash and water according to a solid-to-liquid ratio of a preset proportion, and then washing to obtain fly ash washing liquid and washing slag respectively;
decalcifying the washing slag to obtain decalcified slag, and reselecting the decalcified slag to recover other valuable metals to obtain rare earth slag;
the rare earth slag is diluted and dissolved in concentrated hydrochloric acid according to a solid-to-liquid ratio of a preset proportion, and then is evaporated to dryness to obtain rare earth chloride;
and mixing the rare earth chloride and potassium chloride according to a preset proportion to form electrolyte required by electrolysis, and electrolyzing the electrolyte to obtain the rare earth element.
2. The method for extracting rare earth from fly ash according to claim 1, wherein the step of mixing the rare earth chloride with potassium chloride according to a preset ratio to form an electrolyte required by electrolysis, and the step of electrolyzing the electrolyte to obtain rare earth elements comprises:
mixing potassium chloride in a molten state and anhydrous rare earth chloride according to a preset proportion to form an electrolyte, taking a graphite crucible as an anode and a molybdenum rod and liquid metal as a cathode, and electrolyzing the electrolyte under the action of a direct current electric field to obtain rare earth elements.
3. A method for extracting rare-earth elements from fly ash according to claim 2, wherein the electrolysis temperature is 620-900 ℃.
4. The method for extracting rare earth from fly ash according to claim 1, wherein the steps of pulping fly ash and water according to a solid-to-liquid ratio of a preset proportion, and then washing to obtain fly ash washing liquid and washing slag respectively comprise:
the solid-to-liquid ratio of fly ash to water is 1:6.
5. The method for extracting rare earth from fly ash according to claim 1, wherein the step of dissolving the rare earth slag in concentrated hydrochloric acid according to a solid-to-liquid ratio of a preset proportion and then evaporating to obtain rare earth chloride comprises:
the solid-to-liquid ratio of the rare earth slag to the concentrated hydrochloric acid is 2-5:1.
6. The method for extracting rare earth from fly ash according to claim 1 or 2, wherein the step of mixing the rare earth chloride and potassium chloride according to a preset ratio to form an electrolyte required for electrolysis, and the step of electrolyzing the electrolyte to obtain rare earth elements comprises:
the mixing ratio of the rare earth chloride and the potassium chloride is 1/3-3:1.
7. The method for extracting rare earth from fly ash according to claim 1, wherein the steps of pulping fly ash and water according to a solid-to-liquid ratio of a preset proportion, and then washing to obtain fly ash washing liquid and washing slag respectively further comprise:
and adding a chelating agent into the water washing liquid to remove heavy metals, then adding sodium carbonate to remove calcium and magnesium impurities, and finally cooling and crystallizing to obtain the potassium chloride.
8. The method for extracting rare earth from fly ash according to claim 1, wherein the step of decalcifying the washed slag to obtain decalcified slag, and performing gravity separation on the decalcified slag to recover other valuable metals to obtain rare earth slag comprises:
and leaching the washing slag by adopting carbon dioxide under high pressure to decalcify the washing slag to obtain decalcified slag.
9. The method for extracting rare earth from fly ash according to claim 1, wherein the step of subjecting the washing slag to high pressure carbon dioxide leaching for decalcifying the washing slag to obtain decalcified slag comprises:
uniformly mixing the washing slag and water according to a preset solid-liquid ratio, placing the mixture into a high-pressure reaction kettle, and introducing excessive carbon dioxide into the reaction kettle to obtain decalcified slag;
wherein the solid-liquid ratio of the washing slag to water is 1.
10. The method for extracting rare earth from fly ash according to claim 1, wherein the steps of pulping fly ash and water according to a solid-to-liquid ratio of a preset proportion, and then washing to obtain fly ash washing liquid and washing slag respectively comprise:
pulping the fly ash and water according to a solid-liquid ratio of a preset proportion, introducing carbon dioxide to adjust the pH value to 6-8, and washing to obtain fly ash water washing liquid and water washing slag respectively.
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| US20210347652A1 (en) * | 2020-05-11 | 2021-11-11 | University Of Wyoming | Methods and apparatus for separation of rare earth elements from coal ash |
| CN113955954A (en) * | 2021-08-31 | 2022-01-21 | 江西盖亚环保科技有限公司 | Carbon dioxide high-pressure leaching decalcification process for fly ash |
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