US20240026555A1 - Reduction system and method for high-melting point metal oxides, using liquid metal crucible - Google Patents
Reduction system and method for high-melting point metal oxides, using liquid metal crucible Download PDFInfo
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- US20240026555A1 US20240026555A1 US18/253,346 US202118253346A US2024026555A1 US 20240026555 A1 US20240026555 A1 US 20240026555A1 US 202118253346 A US202118253346 A US 202118253346A US 2024026555 A1 US2024026555 A1 US 2024026555A1
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- 238000000034 method Methods 0.000 title claims abstract description 108
- 150000004706 metal oxides Chemical class 0.000 title claims abstract description 102
- 229910044991 metal oxide Inorganic materials 0.000 title claims abstract description 95
- 229910001338 liquidmetal Inorganic materials 0.000 title claims description 102
- 230000009467 reduction Effects 0.000 title description 14
- 238000002844 melting Methods 0.000 title description 9
- 229910052751 metal Inorganic materials 0.000 claims abstract description 203
- 239000002184 metal Substances 0.000 claims abstract description 203
- 239000002994 raw material Substances 0.000 claims description 98
- 229910045601 alloy Inorganic materials 0.000 claims description 87
- 239000000956 alloy Substances 0.000 claims description 87
- 230000004907 flux Effects 0.000 claims description 69
- 239000010410 layer Substances 0.000 claims description 52
- 239000007787 solid Substances 0.000 claims description 47
- 238000006243 chemical reaction Methods 0.000 claims description 43
- 239000006227 byproduct Substances 0.000 claims description 35
- 229910001092 metal group alloy Inorganic materials 0.000 claims description 34
- 239000012792 core layer Substances 0.000 claims description 30
- 230000005496 eutectics Effects 0.000 claims description 18
- 239000011777 magnesium Substances 0.000 claims description 16
- 239000007788 liquid Substances 0.000 claims description 14
- 229910052759 nickel Inorganic materials 0.000 claims description 14
- 230000005484 gravity Effects 0.000 claims description 12
- 229910052742 iron Inorganic materials 0.000 claims description 12
- 239000000843 powder Substances 0.000 claims description 12
- 229910052719 titanium Inorganic materials 0.000 claims description 12
- 229910052721 tungsten Inorganic materials 0.000 claims description 12
- 229910052725 zinc Inorganic materials 0.000 claims description 12
- 229910052726 zirconium Inorganic materials 0.000 claims description 11
- 229910052749 magnesium Inorganic materials 0.000 claims description 9
- 239000000203 mixture Substances 0.000 claims description 9
- 229910052804 chromium Inorganic materials 0.000 claims description 8
- 229910052802 copper Inorganic materials 0.000 claims description 8
- 229910052748 manganese Inorganic materials 0.000 claims description 8
- 229910052758 niobium Inorganic materials 0.000 claims description 8
- 229910052718 tin Inorganic materials 0.000 claims description 8
- 229910052791 calcium Inorganic materials 0.000 claims description 7
- 230000003647 oxidation Effects 0.000 claims description 7
- 238000007254 oxidation reaction Methods 0.000 claims description 7
- -1 halide salt Chemical class 0.000 claims description 6
- 239000011261 inert gas Substances 0.000 claims description 6
- 150000002739 metals Chemical class 0.000 claims description 6
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims description 6
- 229910052783 alkali metal Inorganic materials 0.000 claims description 5
- 150000001340 alkali metals Chemical class 0.000 claims description 5
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims description 5
- 150000001342 alkaline earth metals Chemical class 0.000 claims description 5
- 229910052695 Americium Inorganic materials 0.000 claims description 4
- 229910052684 Cerium Inorganic materials 0.000 claims description 4
- 229910052685 Curium Inorganic materials 0.000 claims description 4
- 229910052692 Dysprosium Inorganic materials 0.000 claims description 4
- 229910052691 Erbium Inorganic materials 0.000 claims description 4
- 229910052689 Holmium Inorganic materials 0.000 claims description 4
- 229910052764 Mendelevium Inorganic materials 0.000 claims description 4
- 229910052779 Neodymium Inorganic materials 0.000 claims description 4
- 229910052781 Neptunium Inorganic materials 0.000 claims description 4
- 229910052778 Plutonium Inorganic materials 0.000 claims description 4
- 229910052777 Praseodymium Inorganic materials 0.000 claims description 4
- 229910052774 Proactinium Inorganic materials 0.000 claims description 4
- 229910052772 Samarium Inorganic materials 0.000 claims description 4
- 229910052771 Terbium Inorganic materials 0.000 claims description 4
- 229910052776 Thorium Inorganic materials 0.000 claims description 4
- 229910052775 Thulium Inorganic materials 0.000 claims description 4
- 229910052770 Uranium Inorganic materials 0.000 claims description 4
- 229910052769 Ytterbium Inorganic materials 0.000 claims description 4
- 229910052767 actinium Inorganic materials 0.000 claims description 4
- 229910000905 alloy phase Inorganic materials 0.000 claims description 4
- 239000011575 calcium Substances 0.000 claims description 4
- 229910052735 hafnium Inorganic materials 0.000 claims description 4
- 229910052745 lead Inorganic materials 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 229910052720 vanadium Inorganic materials 0.000 claims description 4
- 230000008569 process Effects 0.000 description 63
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 39
- 239000001301 oxygen Substances 0.000 description 39
- 229910052760 oxygen Inorganic materials 0.000 description 39
- 239000010936 titanium Substances 0.000 description 29
- 238000006722 reduction reaction Methods 0.000 description 20
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 11
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 11
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 10
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 9
- 230000007613 environmental effect Effects 0.000 description 9
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 8
- 229910010380 TiNi Inorganic materials 0.000 description 8
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 8
- 230000008901 benefit Effects 0.000 description 8
- 239000000292 calcium oxide Substances 0.000 description 8
- 239000010949 copper Substances 0.000 description 8
- 230000008018 melting Effects 0.000 description 8
- 239000003638 chemical reducing agent Substances 0.000 description 7
- 239000012467 final product Substances 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- 229910017676 MgTiO3 Inorganic materials 0.000 description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 6
- 238000005260 corrosion Methods 0.000 description 6
- 230000007797 corrosion Effects 0.000 description 6
- 229910052593 corundum Inorganic materials 0.000 description 6
- QDOXWKRWXJOMAK-UHFFFAOYSA-N dichromium trioxide Chemical compound O=[Cr]O[Cr]=O QDOXWKRWXJOMAK-UHFFFAOYSA-N 0.000 description 6
- 239000000395 magnesium oxide Substances 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- 229910001845 yogo sapphire Inorganic materials 0.000 description 6
- 239000000654 additive Substances 0.000 description 5
- 230000000996 additive effect Effects 0.000 description 5
- 238000011109 contamination Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 229910001629 magnesium chloride Inorganic materials 0.000 description 5
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 4
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 4
- 229910001632 barium fluoride Inorganic materials 0.000 description 4
- QVQLCTNNEUAWMS-UHFFFAOYSA-N barium oxide Inorganic materials [Ba]=O QVQLCTNNEUAWMS-UHFFFAOYSA-N 0.000 description 4
- 230000004888 barrier function Effects 0.000 description 4
- 230000000903 blocking effect Effects 0.000 description 4
- 229910052681 coesite Inorganic materials 0.000 description 4
- 229910052906 cristobalite Inorganic materials 0.000 description 4
- 229910001635 magnesium fluoride Inorganic materials 0.000 description 4
- 229910001510 metal chloride Inorganic materials 0.000 description 4
- ZKATWMILCYLAPD-UHFFFAOYSA-N niobium pentoxide Chemical compound O=[Nb](=O)O[Nb](=O)=O ZKATWMILCYLAPD-UHFFFAOYSA-N 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 239000000377 silicon dioxide Substances 0.000 description 4
- 238000004611 spectroscopical analysis Methods 0.000 description 4
- 229910052682 stishovite Inorganic materials 0.000 description 4
- 229910052905 tridymite Inorganic materials 0.000 description 4
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 3
- 239000001110 calcium chloride Substances 0.000 description 3
- 229910001628 calcium chloride Inorganic materials 0.000 description 3
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 3
- 229910001634 calcium fluoride Inorganic materials 0.000 description 3
- 238000004821 distillation Methods 0.000 description 3
- 238000005265 energy consumption Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Inorganic materials [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 description 3
- 230000000149 penetrating effect Effects 0.000 description 3
- ZNOKGRXACCSDPY-UHFFFAOYSA-N tungsten(VI) oxide Inorganic materials O=[W](=O)=O ZNOKGRXACCSDPY-UHFFFAOYSA-N 0.000 description 3
- 238000005275 alloying Methods 0.000 description 2
- 239000000460 chlorine Substances 0.000 description 2
- 229910052801 chlorine Inorganic materials 0.000 description 2
- 239000011247 coating layer Substances 0.000 description 2
- UBEWDCMIDFGDOO-UHFFFAOYSA-N cobalt(II,III) oxide Inorganic materials [O-2].[O-2].[O-2].[O-2].[Co+2].[Co+3].[Co+3] UBEWDCMIDFGDOO-UHFFFAOYSA-N 0.000 description 2
- 238000010924 continuous production Methods 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- NLQFUUYNQFMIJW-UHFFFAOYSA-N dysprosium(III) oxide Inorganic materials O=[Dy]O[Dy]=O NLQFUUYNQFMIJW-UHFFFAOYSA-N 0.000 description 2
- 238000007667 floating Methods 0.000 description 2
- QZQVBEXLDFYHSR-UHFFFAOYSA-N gallium(III) oxide Inorganic materials O=[Ga]O[Ga]=O QZQVBEXLDFYHSR-UHFFFAOYSA-N 0.000 description 2
- 230000014509 gene expression Effects 0.000 description 2
- CJNBYAVZURUTKZ-UHFFFAOYSA-N hafnium(IV) oxide Inorganic materials O=[Hf]=O CJNBYAVZURUTKZ-UHFFFAOYSA-N 0.000 description 2
- 150000004820 halides Chemical class 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- XMFOQHDPRMAJNU-UHFFFAOYSA-N lead(II,IV) oxide Inorganic materials O1[Pb]O[Pb]11O[Pb]O1 XMFOQHDPRMAJNU-UHFFFAOYSA-N 0.000 description 2
- VASIZKWUTCETSD-UHFFFAOYSA-N manganese(II) oxide Inorganic materials [Mn]=O VASIZKWUTCETSD-UHFFFAOYSA-N 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- BFRGSJVXBIWTCF-UHFFFAOYSA-N niobium monoxide Inorganic materials [Nb]=O BFRGSJVXBIWTCF-UHFFFAOYSA-N 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 238000010079 rubber tapping Methods 0.000 description 2
- 229910000108 silver(I,III) oxide Inorganic materials 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- PBCFLUZVCVVTBY-UHFFFAOYSA-N tantalum pentoxide Inorganic materials O=[Ta](=O)O[Ta](=O)=O PBCFLUZVCVVTBY-UHFFFAOYSA-N 0.000 description 2
- QHGNHLZPVBIIPX-UHFFFAOYSA-N tin(II) oxide Inorganic materials [Sn]=O QHGNHLZPVBIIPX-UHFFFAOYSA-N 0.000 description 2
- 231100000331 toxic Toxicity 0.000 description 2
- 230000002588 toxic effect Effects 0.000 description 2
- 238000009834 vaporization Methods 0.000 description 2
- 230000008016 vaporization Effects 0.000 description 2
- CPELXLSAUQHCOX-UHFFFAOYSA-M Bromide Chemical compound [Br-] CPELXLSAUQHCOX-UHFFFAOYSA-M 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- KOPBYBDAPCDYFK-UHFFFAOYSA-N Cs2O Inorganic materials [O-2].[Cs+].[Cs+] KOPBYBDAPCDYFK-UHFFFAOYSA-N 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- FUJCRWPEOMXPAD-UHFFFAOYSA-N Li2O Inorganic materials [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- KKCBUQHMOMHUOY-UHFFFAOYSA-N Na2O Inorganic materials [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 1
- 241000275031 Nica Species 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- 229910052792 caesium Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 125000001309 chloro group Chemical group Cl* 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- AKUNKIJLSDQFLS-UHFFFAOYSA-M dicesium;hydroxide Chemical compound [OH-].[Cs+].[Cs+] AKUNKIJLSDQFLS-UHFFFAOYSA-M 0.000 description 1
- XUCJHNOBJLKZNU-UHFFFAOYSA-M dilithium;hydroxide Chemical compound [Li+].[Li+].[OH-] XUCJHNOBJLKZNU-UHFFFAOYSA-M 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000000921 elemental analysis Methods 0.000 description 1
- XMBWDFGMSWQBCA-UHFFFAOYSA-N hydrogen iodide Chemical compound I XMBWDFGMSWQBCA-UHFFFAOYSA-N 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910003465 moissanite Inorganic materials 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000012805 post-processing Methods 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- NOTVAPJNGZMVSD-UHFFFAOYSA-N potassium monoxide Inorganic materials [K]O[K] NOTVAPJNGZMVSD-UHFFFAOYSA-N 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 229910052701 rubidium Inorganic materials 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 235000015096 spirit Nutrition 0.000 description 1
- 229910052712 strontium Inorganic materials 0.000 description 1
- IATRAKWUXMZMIY-UHFFFAOYSA-N strontium oxide Inorganic materials [O-2].[Sr+2] IATRAKWUXMZMIY-UHFFFAOYSA-N 0.000 description 1
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 description 1
- DUNKXUFBGCUVQW-UHFFFAOYSA-J zirconium tetrachloride Chemical compound Cl[Zr](Cl)(Cl)Cl DUNKXUFBGCUVQW-UHFFFAOYSA-J 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
- C25C3/36—Alloys obtained by cathodic reduction of all their ions
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
- C25C3/26—Electrolytic production, recovery or refining of metals by electrolysis of melts of titanium, zirconium, hafnium, tantalum or vanadium
- C25C3/28—Electrolytic production, recovery or refining of metals by electrolysis of melts of titanium, zirconium, hafnium, tantalum or vanadium of titanium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B34/00—Obtaining refractory metals
- C22B34/10—Obtaining titanium, zirconium or hafnium
- C22B34/12—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08
- C22B34/1263—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining metallic titanium from titanium compounds, e.g. by reduction
- C22B34/1268—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining metallic titanium from titanium compounds, e.g. by reduction using alkali or alkaline-earth metals or amalgams
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B34/00—Obtaining refractory metals
- C22B34/10—Obtaining titanium, zirconium or hafnium
- C22B34/12—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08
- C22B34/1263—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining metallic titanium from titanium compounds, e.g. by reduction
- C22B34/1277—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining metallic titanium from titanium compounds, e.g. by reduction using other metals, e.g. Al, Si, Mn
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B5/00—General methods of reducing to metals
- C22B5/02—Dry methods smelting of sulfides or formation of mattes
- C22B5/04—Dry methods smelting of sulfides or formation of mattes by aluminium, other metals or silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
- C22B9/04—Refining by applying a vacuum
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
- C22B9/05—Refining by treating with gases, e.g. gas flushing also refining by means of a material generating gas in situ
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
- C22B9/10—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals with refining or fluxing agents; Use of materials therefor, e.g. slagging or scorifying agents
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
- C22B9/14—Refining in the solid state
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- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
- C25C3/26—Electrolytic production, recovery or refining of metals by electrolysis of melts of titanium, zirconium, hafnium, tantalum or vanadium
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- C—CHEMISTRY; METALLURGY
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- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
- C25C3/30—Electrolytic production, recovery or refining of metals by electrolysis of melts of manganese
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
- C25C3/34—Electrolytic production, recovery or refining of metals by electrolysis of melts of metals not provided for in groups C25C3/02 - C25C3/32
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- C—CHEMISTRY; METALLURGY
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- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
- C25C7/005—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells of cells for the electrolysis of melts
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
- C25C7/06—Operating or servicing
Definitions
- the present disclosure relates to a system and a method for reducing a high-melting-point metal oxide using a liquid metal crucible.
- the metal M may be obtained by reducing a raw material such as an oxide or halide.
- a method which is relatively well-known and most widely commonly used in the art, is the so-called Kroll process.
- the Kroll process may be summarized as a process in which molten magnesium is used as a reducing agent and a chloride of the desired metal M, such as titanium chloride or zirconium chloride, is added thereto and reduced to titanium or zirconium.
- a chloride of the desired metal M such as titanium chloride or zirconium chloride
- this Kroll process is a process that uses chloride as a raw material, chlorine gas and magnesium chloride are generated as by-products during the process.
- chlorine gas is regarded as a representative problem of the Kroll process, which is an environmental problem that causes fatal problems to the human body, and magnesium chloride causes process problems such as rapid corrosion of reaction vessels called cells, melting furnaces or crucibles or the like.
- the Kroll process requires an additional device to overcome environmental regulations, and involves frequent replacement of reaction vessels, resulting in high costs for operating the process.
- the metal obtained through the Kroll is in the form of a sponge including a large number of pores, and thus it is very difficult to control oxygen that may exist in the metal.
- the Kroll process has limitations in obtaining high-purity metals.
- the above method has a problem in that a reducing agent having strong reducing power directly contacts a portion of the reactor due to the characteristics of the process system, causing corrosion of the reaction vessel, similar to the Kroll process.
- An object of the present disclosure is to provide a technology capable of overcoming the above-described problems.
- the present disclosure provides a system optimized for obtaining a desired metal from a metal oxide without using a metal chloride or using chloride as a flux, and a method capable of producing this metal. Accordingly, the present disclosure is capable of resolving the environmental problems of the above-described Kroll process and the cost problems caused by cell corrosion.
- the present disclosure provides a technology capable of obtaining a large amount of high-purity metal while facilitating the operation of the process according to the following aspects.
- a system and method provided in the present disclosure are characterized by using a liquid metal crucible that includes a liquid metal alloy of metal M 1 and metal M 2 forming a eutectic phase with each other.
- liquid metal crucible may significantly reduce energy consumption, leading to cost reduction. This because when a metal oxide included in a raw material module is reduced to metal M 1 , the melting point of metal M 1 is lowered by a eutectic reaction so that electrolytic reduction may be effectively performed at a relatively low temperature.
- a liquid alloy (M 1 and M 2 form a liquid metal alloy) is obtained by a eutectic reaction, and thus the metal alloy itself may be used as a final product. Since the final product derived from such a liquid alloy has a significantly smaller specific surface area that may be in contact with oxygen than the sponge-type product of the Kroll process, the system and method of the present disclosure may minimize the problem of oxygen contamination of the product.
- metal M 1 may be obtained by electrorefining the obtained metal alloy.
- the liquid alloy thus obtained may be completely isolated from an environment in which oxygen may exist, and thus contamination thereof by oxygen may be significantly prevented. That is, according to the above aspect, it is possible to obtain a high-purity metal alloy and metal M 1 .
- raw materials for example, an oxide containing a desired metal, a reducing agent, and an alloying metal
- the system and method are characterized by using such a raw material module.
- the raw materials are likely to be oxidized or contaminated with oxygen before being introduced.
- the raw material module according to the present disclosure includes a structure treated to be prevented from oxidation, and thus has a more enhanced oxygen barrier effect compared to the Kroll process. Accordingly, the metal alloy and metal obtained according to the present disclosure may have a remarkably low oxygen content. In other words, according to the present disclosure, it is possible to obtain a high-purity metal alloy and metal having little oxygen.
- a system for reducing a metal oxide to metal M 1 is provided.
- a system may include: a cell; a liquid metal crucible accommodated at the bottom of the cell and including a liquid metal alloy of metal M 1 and metal M 2 forming a eutectic phase with each other; a liquid flux accommodated in the cell while forming a layer on the liquid metal crucible without being mixed with the liquid metal crucible; and a solid raw material module including a metal oxide, metal M 2 , and reducing metal M 3 , wherein the metal oxide is reduced to metal M 1 by reaction with reducing metal M 3 while the solid raw material module reaches the liquid metal crucible and is melted, and the reduced metal M 1 and metal M 2 are continuously incorporated into the liquid metal crucible while forming a liquid metal alloy.
- the system may further include an electrorefining part configured to collect and electrorefine the liquid metal alloy formed by the reduced metal M 1 and metal M 2 to obtain metal M 1 .
- the metal oxide may include at least one selected from the group consisting of M 1 x O z and M 1 x M 3 y O z , wherein x and y are each a real number ranging from 1 to 3, and z is a real number ranging from 1 to 4.
- the solid raw material module may include: a core layer including the metal oxide and the reducing metal M 3 ; and a shell layer composed of metal M 2 surrounding the core layer.
- the solid raw material module may be a multilayer structure including: a core layer including the metal oxide; and a shell layer coated to surround the outer surface of the core layer, wherein the shell layer may include an alloy phase composed of metal M 2 and metal M 3 .
- the solid raw material module may be configured to descend vertically within the cell until it reaches the liquid metal crucible through the flux, and the solid raw material module may descend at a rate of a distance corresponding to 0.1% to 10% of the depth of the cell per min.
- oxide M 3 a O b when the metal oxide is reduced to metal M 1 by reaction with reducing metal M 3 while the solid raw material module is melted, oxide M 3 a O b may be produced, and the oxide M 3 a O b may have a lower specific gravity than that of the flux.
- a and b are each a real number ranging from 1 to 3.
- the oxide M 3 a O b may float on the flux due to a density difference to form a by-product layer.
- the liquid metal alloy may be continuously collected through the bottom of the cell, and the by-product layer may be continuously collected through the top of the cell, thereby enabling a continuous process.
- system may further include a recycling part configured to collect the byproduct layer and mix the same with M 1 x O z to produce M 1 x M 3 y O z .
- the reaction between the metal oxide and the reducing metal may be performed in an inert gas atmosphere and/or air.
- the core layer may be composed of a powder mixture including the metal oxide powder and the reducing metal M 3 powder.
- the core layer may have a multilayer structure including: a first core composed of the metal oxide; and a second core coated to surround the outer surface of the first core and composed of metal M 3 .
- the solid raw material module may further include an oxidation-preventing layer surrounding the shell layer and serving to prevent oxidation of metal included in the core layer and/or the shell layer.
- the oxidation-preventing layer may include at least one selected from the group consisting of LiF, MgF 2 , CaF 2 , BaF 2 , CaCl 2 , MgCl 2 , MgO, CaO, BaO, Al 2 O 3 and SiO 2 .
- metal M 1 may be one selected from the group consisting of Ti, Zr, Hf, W, Fe, Ni, Zn, Co, Mn, Cr, Ta, Ga, Nb, Sn, Ag, La, Ce, Pr, Nd, Nb, Pm, Sm, Eu, Al, V, Mo, Gd, Tb, Dy, Ho, Er, Tm, Yb, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md and No, metal M 2 may be at least one selected from the group consisting of Cu, Ni, Fe, Sn, Zn, Pb, Bi, Cd, and alloys thereof, and metal M 3 may be at least one selected from the group consisting of Ca, Mg, Al, and alloys thereof.
- a method of reducing and refining a metal oxide to metal M 1 is provided.
- a method may include: providing a cell; introducing a liquid flux into the cell; introducing metal M 1 and metal M 2 forming a eutectic phase with each other, thereby producing a liquid metal crucible having a specific gravity higher than that of the flux and accommodated in the cell while forming a layer under the flux without being mixed with the flux; moving a solid raw material module including a metal oxide, metal M 2 and reducing metal M 3 to the cell until it reaches the liquid metal crucible through the flux; and obtaining a liquid metal alloy including metal M 1 derived from the metal oxide of the solid raw material module and metal M 2 .
- oxide M 3 a O b may be produced as a by-product in moving the solid raw material module and/or obtaining the liquid metal alloy, and the oxide M 3 a O b may have a lower specific gravity than that of the flux, and the method may further include continuously collecting the by-product M 3 a O b forming a layer on the flux, and adding and mixing M 1 x O z with the collected M 3 a O b , thereby producing a metal oxide expressed as M 1 x M 3 y O z derived from the by-product M 3 a O b and the added M 1 x O z .
- three is provided a metal alloy or metal produced by the method according to the above-described example embodiment, wherein the metal alloy may have a residual reducing metal M 3 content of 0.1 wt % or less, specifically 0.01 wt % or less, more specifically 0.001 wt % or less, based on the total weight of the metal alloy, and an oxygen content of 1,200 ppm or less, specifically 1,000 ppm or less, more specifically 990 ppm or less.
- the present disclosure provides a system optimized for obtaining a desired metal from a metal oxide without using a metal chloride or using chloride as a flux, and a method for producing this metal. Accordingly, the present disclosure is capable of resolving the environmental problems of the above-described Kroll process and the cost problems caused by cell corrosion.
- the system and method provided in the present disclosure are characterized by using a liquid metal crucible that includes a liquid metal alloy of metal M 1 and metal M 2 forming a eutectic phase with each other.
- a liquid metal crucible may significantly reduce energy consumption, leading to cost reduction. This because when a metal oxide included in a module, which is a raw material, is reduced to metal M 1 , the melting point of metal M 1 is lowered by a eutectic reaction so that electrolytic reduction may be effectively performed at a relatively low temperature.
- a liquid alloy (M 1 and M 2 form a liquid metal alloy) is obtained by a eutectic reaction, and thus the metal alloy itself may be used as a final product. Since the final product derived from such a liquid alloy has a significantly smaller specific surface area that may be in contact with oxygen than the sponge-type product of the Kroll process, the system and method of the present disclosure may minimize the problem of oxygen contamination of the product.
- the liquid alloy thus obtained may be completely isolated from an environment in which oxygen may exist, and thus contamination thereof by oxygen may be significantly prevented. That is, according to the foregoing, it is possible to obtain a high-purity metal alloy and metal M 1 .
- raw materials for example, an oxide containing a desired metal, a reducing agent, and an alloying metal
- the system and method are characterized by using such a raw material module.
- the raw materials are likely to be oxidized or contaminated with oxygen before being introduced.
- the raw material module according to the present disclosure includes a structure treated to be prevented from oxidation, and thus has a more enhanced oxygen barrier effect compared to the Kroll process. Accordingly, the metal alloy and metal obtained according to the present disclosure may have a remarkably low oxygen content. In other words, according to the present disclosure, it is possible to obtain a high-purity metal alloy and metal having little oxygen.
- FIG. 1 is a schematic view of a system according to one example embodiment of the present disclosure
- FIG. 2 depicts photographs showing a process of preparing a raw material module including MgTiO 3 as a metal oxide according to one example embodiment of the present disclosure
- FIG. 3 is a graph showing the results of XRD analysis of the raw material module prepared as shown in FIG. 2 ;
- FIG. 4 is a schematic vertical sectional view of a raw material module according to one example embodiment of the present disclosure
- FIG. 5 is a schematic vertical sectional view of a raw material module according to another example embodiment of the present disclosure.
- FIG. 6 is a schematic vertical sectional view of a raw material module according to still another example embodiment of the present disclosure.
- FIG. 7 is a photograph of a raw material module
- FIG. 8 is another photograph of a raw material module
- FIG. 9 depicts photographs showing the results of comparing weight before and after removing the flux from the alloy ingot produced in an Example
- FIG. 10 is a table showing the results of performing elemental analysis of the inside of an alloy, produced in an Example, by energy dispersive spectrometry (EDS) after cutting the alloy; and
- FIG. 11 is a table showing the results of measuring the content of oxygen present in the alloy using ELTRA ONH2000.
- charging as used in the present specification may be used interchangeably with the term “feeding”, “introducing”, “flowing in”, or “injection”, and may be understood to mean sending or putting any material, such as a raw material, into a place where it is needed.
- a system for a metal oxide to metal M 1 according to the present disclosure is schematically shown in FIG. 1 .
- the system according to the present disclosure may include: a cell 400 ; a liquid metal crucible 100 accommodated at the bottom of the cell 400 and including a liquid metal alloy of metal M 1 and metal M 2 forming a eutectic phase with each other; a liquid flux 200 accommodated in the cell while forming a layer on the liquid metal crucible 100 without being mixed with the liquid metal crucible, so as to block oxygen and reaction by-products from flowing into the liquid metal crucible 100 ; and a solid raw material module 300 including a metal oxide, metal M 2 , and reducing metal M 3 , wherein the metal oxide may be reduced to metal M 1 by reaction with the reducing metal M 3 while the solid raw material module reaches the liquid metal crucible and is melted, and the reduced metal M 1 and metal M 2 may be continuously incorporated into the liquid metal crucible while forming a
- the desired metal M 1 is not particularly limited, but may be specifically one selected from the group consisting of Ti, Zr, Hf, W, Fe, Ni, Zn, Co, Mn, Cr, Ta, Ga, Nb, Sn, Ag, La, Ce, Pr, Nd, Nb, Pm, Sm, Eu, Al, V, Mo, Gd, Tb, Dy, Ho, Er, Tm, Yb, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md and No.
- the desired metal M 1 may be one selected from the group consisting of Ti, Zr, W, Fe, Ni, Zn, Co, Mn, Cr, Ta, Er and No, and more specifically, may be one selected from the group consisting of Ti, Zr, W, Fe, Ni, Zn, Co, Mn, and Cr. Even more specifically, it may be Ti, Zr or W.
- metal M 2 is not particularly limited as long as it can form a liquid metal alloy by a eutectic reaction with metal M 1 .
- metal M 2 may be at least one selected from the group consisting of Cu, Ni, Fe, Sn, Zn, Pb, Bi, Cd, and alloys thereof, and more specifically, may be Cu, Ni, or an alloy thereof.
- metal M 3 is not particularly limited as long as it can reduce the metal oxide to M 1 .
- metal M 3 may be at least one selected from among Ca, Mg, Al, and alloys thereof, and more specifically, may be Ca or Mg, in particular, Mg.
- the metal oxide may include at least one selected from the group consisting of M 1 x O z and M 1 x M 3 y O z , wherein x and y are each a real number ranging from 1 to 3, and z is a real number ranging from 1 to 4.
- the metal oxide may include one or a combination of two or more selected from the group consisting of ZrO 2 , TiO 2 , MgTiO 3 , HfO 2 , Nb 2 O 5 , Dy 2 O 3 , Tb 4 O 7 , WO 3 , Co 3 O 4 , MnO, Cr 2 O 3 , MgO, CaO, Al 2 O 3 , Ta 2 O 5 , Ga 2 O 3 , Pb 3 O 4 , SnO, NbO and Ag 2 O, without being limited thereto.
- the system according to the present disclosure is different from the conventional Kroll process in that it uses a metal oxide instead of a metal chloride as a raw material.
- Raw materials usually found in nature include an oxide of metal M 1 , and in order to use this metal oxide in the Kroll process, a pretreatment process of substituting the metal oxide with a chloride needs to be performed. If this pretreatment process is performed, it itself will cause an increase in process cost.
- hydrochloric acid is used in the pretreatment process of substituting the metal oxide with a chloride, and in this case, corrosion of production equipment may be promoted due to the strong acidity of the hydrochloric acid, and toxic chlorine gas may be generated during the process, which may cause environmental problems.
- the system according to the present disclosure has advantages over the Kroll process in that it does not require the pretreatment process of substituting the metal oxide with a chloride, and thus it incurs a lower cost than the Kroll process cost and does not cause environmental problems.
- the cell 400 is preferably made of a material that has a high melting point in terms of durability and does not cause side reactions with the flux and the liquid metal crucible.
- the material of the cell may include at least one selected from the group consisting of MgO, Cr 2 O 3 , Al 2 O 3 , SiO 2 , CaO, SiC, WO 3 , W, C, and Mo, without being limited thereto.
- the cell 400 may include a tapping hole 410 for continuously tapping the liquid metal alloy produced at the bottom thereof.
- liquid metal crucible may refer to a reaction region capable of providing an environment in which at least one metal may be accommodated in, for example, the cell in a molten state while forming one layer, and the raw material module of the present disclosure may be melted within and the layer surface of the melted metal so that the metal oxide may be reduced.
- the system according to the present disclosure has the advantage of using this liquid metal crucible.
- melting point of metal M 1 may be lowered by the eutectic reaction while the metal oxide of the raw material module is reduced to metal M 1 , and thus electrolytic reduction may be effectively performed at a relatively low temperature. That is, in the system of the present disclosure, it is possible to obtain a liquid metal alloy while operating a liquid metal crucible in which metals are melted, and it is possible to operate the process at a lower temperature than the melting point of metal M 1 , thereby significantly reducing energy consumption. This temperature may vary depending on the types of M 1 and M 2 , but may preferably be 900° C. to 1,600° C.
- a liquid alloy (M 1 and M 2 form a liquid metal alloy) may be obtained based on the eutectic reaction induced in the system of the present disclosure, and the metal alloy itself may be used as a final product.
- M 1 is often used industrially in the form of an alloy.
- a post-processing process for forming an alloy with another metal may be required.
- the present disclosure has high process efficiency in that it is possible to obtain a final product in the form of a metal alloy of M 1 and M 2 through reduction reaction without the above-described post-treatment process.
- metal M 1 may be obtained by electrorefining the obtained metal alloy, and a method known in the art may be used for such electrolytic refining.
- the liquid alloy obtained according to the present disclosure may be completely isolated from an environment in which oxygen may exist, and thus contamination thereof by oxygen may be significantly prevented. That is, according to the above aspect, it is possible to obtain a high-purity metal alloy and metal M 1 .
- the use of the liquid metal crucible including the liquid metal alloy of metal M 1 and metal M 2 forming a eutectic phase with each other has an advantage in that, even if the metal oxide contained in the raw material module is a material that is difficult to electrolytically reduce to metal, it is possible to more easily reduce the metal oxide in the raw material module using the standard oxidation-reduction potential difference between the liquid metal alloy and the desired metal M 1 . That is, when metal M 2 having a more positive standard reduction potential that of metal M 1 is used, the standard reduction potential value of M 1 may move in a positive direction due to the liquid metal crucible, so that electrolytic reduction of the metal may be more easily achieved.
- a metal oxide as a raw material, another metal as a reducing agent, and other additive metals are not introduced, but they constitute a raw material module like a single part, and based on this raw material module, it is possible to obtain a higher-quality metal alloy and metal.
- the raw materials are likely to be oxidized before being introduced, but the raw material module according to the present disclosure includes a structure treated to be prevented from oxidation, and thus has a more enhanced oxygen barrier effect compared to the Kroll process. Accordingly, the metal alloy and metal obtained according to the present disclosure may have a significantly low oxygen content.
- the system of the present disclosure includes a configuration for doubly blocking oxygen, because the flux serves as a barrier layer for blocking oxygen, and the raw material module itself can also block oxygen. Accordingly, the system of the present disclosure has significant advantages in that it is possible to perform the reaction between the metal oxide and the reducing metal under an inert gas atmosphere, which has been commonly recognized in the art, and it is also possible to perform the reaction between the metal oxide and the reducing metal in air. Even if the system of the present disclosure is operated in air, the metal alloy and metal produced thereby are of high purity with little oxygen. This will be clearly demonstrated through examples to be described later. In some cases, in the system of the present disclosure, the reaction between the metal oxide and the reducing metal may be performed in a combination of an inert gas atmosphere and a normal air atmosphere.
- the system of the present disclosure uses a raw material module in which raw materials necessary for the reaction are gathered into one body, and thus has an advantage in that it is easy to induce the reaction at the most optimal location in the cell.
- FIG. 2 Photographs showing a process of preparing a raw material module according to the present disclosure are depicted in FIG. 2
- FIG. 4 shows a schematic view of a raw material module according to one example embodiment of the present disclosure.
- the photographs shown in FIG. 2 are only for helping understanding of the preparation of the raw material module as a non-limiting example, and the scope of the present disclosure is not limited thereto.
- the solid raw material module 300 may include: a core layer 30 including the metal oxide 10 and the reducing metal M 3 30 ; and a shell layer 320 composed of metal M 2 surrounding the core layer 310 .
- the core layer 310 may have a multilayer structure including: a first core 311 composed of the metal oxide 10 ; and a second core 312 coated to surround the outer surface of the first core 311 and composed of the reducing metal M 3 30 .
- a raw material module 300 a as shown in FIG. 5 in which a core layer is shown as another example of the present disclosure may be used.
- the core layer 310 a of the raw material module 300 a may be composed of a powdery mixture including metal oxide powder 10 a and reducing metal M 3 powder 30 a.
- the structure shown in FIG. 6 may also be preferable as the raw material module.
- the raw material module 300 b is similar to the above-described example in terms of a multilayer structure, but is different from the above-described example in that it includes the core layer 310 b including the metal oxide 10 b and the shell layer 320 b coated to surround the outer surface of the core layer 310 b , wherein the shell layer 320 b is a coating layer including an alloy phase 330 b composed of the metal M 2 20 b and the metal M 3 30 b.
- the above-described solid raw material module may further include an oxidation-preventing layer ( 330 in FIG. 4 ) surrounding the shell layer and serving to prevent oxidation of metal included in the core layer and/or the shell layer by blocking oxygen from contacting the metal.
- the oxidation-preventing layer 330 may include at least one selected from the group consisting of LiF, MgF 2 , CaF 2 , BaF 2 , CaCl 2 , MgCl 2 , MgO, CaO, BaO, Al 2 O 3 and SiO 2 , but the scope of the present disclosure is not limited thereto.
- the oxidation-preventing layer is shown only in FIG. 4 , it is to be understood that the oxidation-preventing layer may also be applied to the other example embodiments shown in FIGS. 5 and 6 .
- This solid raw material module may be configured to descend vertically within the cell until it reaches the liquid metal crucible through the flux.
- the solid raw material module may descend at a rate of a distance corresponding to 0.1% to 10% of the depth of the cell per min.
- rotating the solid raw material module about the axis is preferable in terms of stirring the liquid metal crucible and improving reactivity thereby.
- the rotation may be performed during the descent into the cell and/or until completion of the descent.
- system according to the present disclosure may further include a rotation unit to which the solid raw material module is mounted and which rotates the same.
- the solid raw material module descends to the liquid metal crucible and is melted, and at the same time or partially simultaneously, the metal oxide and the reducing metal M 3 react to reduce the metal oxide to M 1 , and the reduced M 1 forms a liquid metal alloy with M 2 contained in the solid raw material module.
- the metal oxide (M 1 x O z ) is TiO 2
- M 2 is Ni
- M 3 is Mg
- the metal oxide may be reduced to metal Ti, and then an M 3 oxide (M 3 a O b ) may be separated while the liquid metal alloy TiNi is obtained.
- the metal oxide (M 1 x M 3 y O z ) is MgTiO 3
- M 2 is Ni
- M 3 is Mg
- Reaction Formulas 2-1 and 2-2 below the metal oxide may be reduced to metal Ti, and then an M 3 oxide (M 3 a O b ) may be separated while the liquid metal alloy TiNi is obtained.
- M 3 aO b produced according to the above-described reaction is a kind of by-product and may have a lower specific gravity that that of the flux of the present disclosure.
- the M 3 a O b may float on the flux due to its density difference from the flux to form a by-product layer. Therefore, the by-product M 3 a O b does not mix with the liquid metal crucible present as a layer under the flux and with the formed liquid metal alloy.
- the by-product layer may serve to prevent the flux from being lost by vaporization while being positioned on the flux, and to prevent oxygen in the air from penetrating into the reactor.
- the system according to the present disclosure may be configured to enable a continuous process by using this by-product.
- the system of the present disclosure may further include a recycling device that continuously collects the layered by-product floating on the flux through the top of the cell and mixes the collected by-product with, for example, M 1 x O z to produce metal oxide M 1 x M 3 y O z .
- M 1 x O z the reduction reaction rate may be further increased compared to when M 1 x O z is used.
- the flux preferably has a specific gravity which is intermediate between the specific gravity of the liquid metal crucible and the specific gravity of the by-product M 3 a O b so as to prevent the liquid metal crucible and the by-product M 3 a O b from mixing with each other, and at the same time, the flux is preferably insoluble in the by-product M 3 a O b .
- the flux is preferably a material such as a non-chlorine-based material, which does not cause environmental problems while being capable of preventing prevent oxygen from penetrating into the liquid metal crucible and the liquid metal alloy containing the desired metal M 1 .
- This flux may include a molten halide salt of at least one metal selected from the group consisting of alkali metals and alkaline earth metals, but does not contain chloride. More specifically, the flux in the system of the present disclosure may be a molten halide salt of at least one metal selected from the group consisting of alkali metals including Li, Na, K, Rb, and Cs, and alkaline earth metals including Mg, Ca, Sr, and Ba. In this case, the halide may include fluoride, bromide, iodide, or a mixture thereof.
- the flux may also be present in an amount of 10 wt % to 50 wt %, specifically 10 wt % to 20 wt %, more specifically 10 wt % to 15 wt %, even more specifically 12 wt % to 13 wt %, relative to the metal oxide involved in the overall reduction reaction, that is, the metal oxide contained in the raw material module and capable of being reduced to the desired metal M 1 .
- the flux may further contain, as an additive, at least one metal oxide selected from the group of alkali metals and alkaline earth metals.
- the content of the additive may be 0.1 to 25 wt % based on the total weight of the flux.
- the additive may include Li 2 O, Na 2 O, SrO, Cs 2 O, K 2 O, CaO, BaO, or a mixture thereof, without being limited thereto.
- the additive contained in the flux may enable easier reduction of the metal oxide contained in the raw material module.
- the system according to the present disclosure may further include an electrorefining part configured to continuously collect the liquid metal alloy formed by M 1 and M 2 through the bottom of the cell and to electrorefine the collected liquid metal alloy to obtain metal M 1 .
- the electrorefining part may solidify the collected liquid metal alloy to obtain a solid metal alloy, and electrorefine the solid metal alloy, thereby recovering metal M 1 from the metal alloy.
- a flux that may remain in the liquid metal alloy may be removed before electrorefining of the solid metal alloy, and this removal may be achieved, for example, by heat-treating the liquid metal alloy in a vacuum or inert gas atmosphere, causing the flux to be removed by distillation.
- the distillation temperature heat treatment temperature
- the distillation temperature is not particularly limited as long as it is a temperature equal to or higher than the melting point of the flux used in the system of the present disclosure, and it may be, for example, 780 to 1,000° C.
- the electrorefining part may include a flux including a molten halide salt of at least one metal selected from the group consisting of alkali metals and alkaline earth metals, independently of the flux used in the above-described reduction reaction.
- the method according to the present disclosure may include the operations of: providing a cell; introducing a liquid flux into the cell; introducing metal M 1 and metal M 2 forming a eutectic phase with each other, thereby producing a liquid metal crucible having a specific gravity higher than that of the flux and accommodated in the cell while forming a layer under the flux without being mixed with the flux; moving a solid raw material module including a metal oxide, metal M 2 and reducing metal M 3 to the cell until it reaches the liquid metal crucible through the flux; and obtaining a liquid metal alloy including metal M 1 derived from the metal oxide of the solid raw material module and metal M 2 .
- the metal oxide and the reducing metal M 3 may react with each other to reduce the metal oxide to metal M 1 , and the reduced metal M 1 and metal M 2 may be continuously incorporated into the liquid metal crucible while forming a liquid metal alloy.
- the desired metal M 1 is not particularly limited, but may be specifically one selected from the group consisting of Ti, Zr, Hf, W, Fe, Ni, Zn, Co, Mn, Cr, Ta, Ga, Nb, Sn, Ag, La, Ce, Pr, Nd, Nb, Pm, Sm, Eu, Al, V, Mo, Gd, Tb, Dy, Ho, Er, Tm, Yb, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md and No.
- the desired metal M 1 may be one selected from the group consisting of Ti, Zr, W, Fe, Ni, Zn, Co, Mn, Cr, Ta, Er and No, and more specifically, may be one selected from the group consisting of Ti, Zr, W, Fe, Ni, Zn, Co, Mn, and Cr. Even more specifically, it may be Ti, Zr or W.
- metal M 2 is not particularly limited as long as it can form a liquid metal alloy by a eutectic reaction with metal M 1 .
- metal M 2 may be at least one selected from the group consisting of Cu, Ni, Fe, Sn, Zn, Pb, Bi, Cd, and alloys thereof, and more specifically, may be Cu, Ni, or an alloy thereof.
- metal M 3 is not particularly limited as long as it can reduce the metal oxide to M 1 .
- metal M 3 may be at least one selected from among Ca, Mg, Al, and alloys thereof, and more specifically, may be Ca or Mg, in particular, Mg.
- the metal oxide may include at least one selected from the group consisting of M 1 x O z and M 1 x M 3 y O z , wherein x and y are each a real number ranging from 1 to 3, and z is a real number ranging from 1 to 4.
- the metal oxide may include one or a combination of two or more selected from the group consisting of ZrO 2 , TiO 2 , MgTiO 3 , HfO 2 , Nb 2 O 5 , Dy 2 O 3 , Tb 4 O 7 , WO 3 , Co 3 O 4 , MnO, Cr 2 O 3 , MgO, CaO, Al 2 O 3 , Ta 2 O 5 , Ga 2 O 3 , Pb 3 O 4 , SnO, NbO and Ag 2 O, without being limited thereto.
- the method according to the present disclosure is different from the conventional Kroll process in that it uses a metal oxide instead of a metal chloride as a raw material.
- Raw materials usually found in nature include an oxide of metal M 1 , and in order to use this metal oxide in the Kroll process, a pretreatment process of substituting the metal oxide with a chloride needs to be performed. If this pretreatment process is performed, it itself will cause an increase in process cost.
- hydrochloric acid is used in the pretreatment process of substituting the metal oxide with a chloride, and in this case, corrosion of production equipment may be promoted due to the strong acidity of the hydrochloric acid, and toxic chlorine gas may be generated during the process, which may cause environmental problems.
- the method according to the present disclosure has advantages over the Kroll process in that it does not require the pretreatment process of substituting the metal oxide with a chloride, and thus it incurs a lower cost than the Kroll process cost and does not cause environmental problems.
- the raw material module that is used in the method of the present disclosure may include: a core layer including a metal oxide and reducing metal M 3 ; and a shell layer composed of metal M 2 surrounding the core layer.
- the core layer 310 may have a multilayer structure including: a first core composed of the metal oxide; and a second core coated to surround the outer surface of the first core and composed of the reducing metal M 3 .
- the core layer 310 a of the raw material module 300 a may be composed of a powdery mixture including metal oxide powder and reducing metal M 3 powder.
- the raw material module shown in FIG. 6 may also be used.
- This raw material module may include the core layer including the metal oxide and the shell layer coated to surround the outer surface of the core layer, wherein the shell layer may be a coating layer including an alloy phase composed of metal M 2 and metal M 3 .
- the solid raw material module may further include an oxidation-preventing layer surrounding the shell layer and serving to prevent oxidation of metal included in the core layer and/or the shell layer by blocking oxygen from contacting the metal.
- the oxidation-preventing layer may include at least one selected from the group consisting of LiF, MgF 2 , CaF 2 , BaF 2 , CaCl 2 , MgCl 2 , MgO, CaO, BaO, Al 2 O 3 and SiO 2 , but the scope of the present disclosure is not limited thereto.
- the solid raw material module may be descended at a rate of a distance corresponding to 0.1% to 10% of the depth of the cell per min, until it reaches the liquid metal crucible through the flux.
- the metal oxide may be reduced to metal M 1 by reaction with the reducing metal M 3 , and the reduced M 1 may form a liquid metal alloy with the metal M 2 contained in the solid raw material module.
- the metal oxide (M 1 x O z ) is TiO 2
- M 2 is Ni
- M 3 is Mg
- the metal oxide may be reduced to metal Ti, and then an M 3 oxide (M 3 a O b ) may be separated while the liquid metal alloy TiNi is obtained.
- the metal oxide (M 1 x M 3 y O z ) is MgTiO 3
- M 2 is Ni
- M 3 is Mg
- Reaction Formulas 2-1 and 2-2 below the metal oxide may be reduced to metal Ti, and then an M 3 oxide (M 3 a O b ) may be separated while the liquid metal alloy TiNi is obtained.
- M 3 aO b produced according to the above-described reaction is a kind of by-product and may have a lower specific gravity that that of the flux of the present disclosure.
- the M 3 a O b may float on the flux due to its density difference from the flux to form a by-product layer. Therefore, the by-product M 3 a O b does not mix with the liquid metal crucible present as a layer under the flux and with the formed liquid metal alloy.
- the by-product layer may serve to prevent the flux from being lost by vaporization while being positioned on the flux, and to prevent oxygen in the air from penetrating into the reactor.
- the method according to the present disclosure may be configured to use this by-product.
- the method according to the present disclosure may further include the operation of continuously collecting the layered by-product (i.e., M 3 a O b ) floating on the flux through the top of the cell, and adding and mixing, for example, M 1 x O z with the collected M 3 a O b , thereby producing the metal oxide M 1 x M 3 y O z derived from the by-product M 3 a O b and the added M 1 x O z .
- M 3 a O b the layered by-product floating on the flux through the top of the cell
- the reduction reaction rate may be further increased compared to when M 1 x O z is used.
- the operation of producing M 1 x M 3 y O z may be performed at a temperature of 1,000° C. to 1,500° C., specifically 1,200° C. to 1,400° C., more specifically, 1,250° C. to 1,350° C.
- the type of the flux is not particularly limited unless it is a chlorine-based material, and is preferably as defined in the previous example embodiment.
- the method according to the present disclosure may further include, after the operation of obtaining the alloy including metals M 1 and M 2 , the operation of obtaining metal M 1 by electrorefining the obtained alloy.
- the operation of obtaining metal M 1 by electrorefining may be the operation of solidifying the obtained liquid metal alloy to obtain a solid alloy, and electrorefining the solid alloy, thereby recovering metal M 1 from the alloy.
- Flux MgF 2 (0.2 kg)-BaF 2 (1.5 kg) in a resistance heating furnace was weighed, introduced into a cell, and then heated to about 1,200° C. to form a flux layer.
- the prepared raw material module was charged into the cell and descended vertically at a rate of about 6 cm/min until it reached the layer of the liquid metal crucible. At this time, the module was rotated for 10 minutes to stir the flux and the liquid metal crucible. The melting and reduction reaction of the raw material module was performed for 2 hours, and a CuTi liquid metal alloy as a reaction product was collected through an outlet provided at the bottom of the cell and was solidified to finally obtain a CuTi alloy shown in FIG. 9 . In addition, after completion of the reaction, the crucible was cooled at a rate of ⁇ 10° C./min to prevent damage to the crucible.
- FIG. 10 shows the results obtained by cutting the alloy produced in the Example and analyzing the residual impurity content in the inside of the alloy by energy dispersion spectrometry.
- the alloy is composed only of the desired metal Ti and Cu, and Mg used as the reducing metal does not exist at all.
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Abstract
The present disclosure provides a system and a method for reducing metal oxide to metal M1.
Description
- The present disclosure relates to a system and a method for reducing a high-melting-point metal oxide using a liquid metal crucible.
- When a metal typically known in the art is referred to as any metal “M”, the metal M may be obtained by reducing a raw material such as an oxide or halide. Among the methods for producing the desired metal M, a method, which is relatively well-known and most widely commonly used in the art, is the so-called Kroll process.
- Typically, the Kroll process may be summarized as a process in which molten magnesium is used as a reducing agent and a chloride of the desired metal M, such as titanium chloride or zirconium chloride, is added thereto and reduced to titanium or zirconium. In this regard, more details of the Kroll process may be found in U.S. Pat. No. 5,035,404.
- Since this Kroll process is a process that uses chloride as a raw material, chlorine gas and magnesium chloride are generated as by-products during the process. Among these by-products, chlorine gas is regarded as a representative problem of the Kroll process, which is an environmental problem that causes fatal problems to the human body, and magnesium chloride causes process problems such as rapid corrosion of reaction vessels called cells, melting furnaces or crucibles or the like.
- As such, the Kroll process requires an additional device to overcome environmental regulations, and involves frequent replacement of reaction vessels, resulting in high costs for operating the process.
- In another aspect, the metal obtained through the Kroll is in the form of a sponge including a large number of pores, and thus it is very difficult to control oxygen that may exist in the metal. In other words, the Kroll process has limitations in obtaining high-purity metals.
- Meanwhile, a method of preparing a desired metal alloy using CuCa or NiCa as a reducing agent and then electrorefining the same is being considered to overcome the disadvantages of the Kroll process.
- However, the above method has a problem in that a reducing agent having strong reducing power directly contacts a portion of the reactor due to the characteristics of the process system, causing corrosion of the reaction vessel, similar to the Kroll process. There is also a method of minimizing the influence of the reducing agent by making a reaction vessel composed of W or Mo metal, but the unit cost of the reaction vessel itself is so high that it causes an increase in the overall production cost. In addition, in order to continuously perform the process, it is necessary to remove CaO, which is a by-product generated in the reduction reaction, and a large amount of a flux is required to remove the by-product. This also has a problem of causing an increase in the overall production cost.
- Therefore, at present, there is a demand for a completely new technology capable of not only overcoming the problems of the Kroll process at once but also easily operating the process for obtaining the desired metal M while making it possible to obtain a large amount of the metal with high purity.
- An object of the present disclosure is to provide a technology capable of overcoming the above-described problems.
- The present disclosure provides a system optimized for obtaining a desired metal from a metal oxide without using a metal chloride or using chloride as a flux, and a method capable of producing this metal. Accordingly, the present disclosure is capable of resolving the environmental problems of the above-described Kroll process and the cost problems caused by cell corrosion.
- Furthermore, the present disclosure provides a technology capable of obtaining a large amount of high-purity metal while facilitating the operation of the process according to the following aspects.
- In one aspect of the present disclosure, a system and method provided in the present disclosure are characterized by using a liquid metal crucible that includes a liquid metal alloy of metal M1 and metal M2 forming a eutectic phase with each other.
- The use of such a liquid metal crucible may significantly reduce energy consumption, leading to cost reduction. This because when a metal oxide included in a raw material module is reduced to metal M1, the melting point of metal M1 is lowered by a eutectic reaction so that electrolytic reduction may be effectively performed at a relatively low temperature.
- In addition, in the above system and method, a liquid alloy (M1 and M2 form a liquid metal alloy) is obtained by a eutectic reaction, and thus the metal alloy itself may be used as a final product. Since the final product derived from such a liquid alloy has a significantly smaller specific surface area that may be in contact with oxygen than the sponge-type product of the Kroll process, the system and method of the present disclosure may minimize the problem of oxygen contamination of the product.
- Alternatively, metal M1 may be obtained by electrorefining the obtained metal alloy. The liquid alloy thus obtained may be completely isolated from an environment in which oxygen may exist, and thus contamination thereof by oxygen may be significantly prevented. That is, according to the above aspect, it is possible to obtain a high-purity metal alloy and metal M1.
- In another aspect of the present disclosure, in the system and method provided in the present disclosure, raw materials, for example, an oxide containing a desired metal, a reducing agent, and an alloying metal, form a module like a single part, and the system and method are characterized by using such a raw material module. In a process of continuously introducing a plurality of raw materials into a cell, like the Kroll process, the raw materials are likely to be oxidized or contaminated with oxygen before being introduced. However, the raw material module according to the present disclosure includes a structure treated to be prevented from oxidation, and thus has a more enhanced oxygen barrier effect compared to the Kroll process. Accordingly, the metal alloy and metal obtained according to the present disclosure may have a remarkably low oxygen content. In other words, according to the present disclosure, it is possible to obtain a high-purity metal alloy and metal having little oxygen.
- According to these aspects, it is possible to easily producer a metal having excellent quality while overcoming the conventional problems. Thus, the technical basis for the implementation of the present disclosure will be described in detail below.
- In one example embodiment of the present disclosure, a system for reducing a metal oxide to metal M1 is provided.
- A system according to one example embodiment of the present disclosure may include: a cell; a liquid metal crucible accommodated at the bottom of the cell and including a liquid metal alloy of metal M1 and metal M2 forming a eutectic phase with each other; a liquid flux accommodated in the cell while forming a layer on the liquid metal crucible without being mixed with the liquid metal crucible; and a solid raw material module including a metal oxide, metal M2, and reducing metal M3, wherein the metal oxide is reduced to metal M1 by reaction with reducing metal M3 while the solid raw material module reaches the liquid metal crucible and is melted, and the reduced metal M1 and metal M2 are continuously incorporated into the liquid metal crucible while forming a liquid metal alloy.
- In one specific example embodiment, the system may further include an electrorefining part configured to collect and electrorefine the liquid metal alloy formed by the reduced metal M1 and metal M2 to obtain metal M1.
- In one specific example embodiment, the metal oxide may include at least one selected from the group consisting of M1 xOz and M1 xM3 yOz, wherein x and y are each a real number ranging from 1 to 3, and z is a real number ranging from 1 to 4.
- In one specific example embodiment, the solid raw material module may include: a core layer including the metal oxide and the reducing metal M3; and a shell layer composed of metal M2 surrounding the core layer.
- In one specific example embodiment, the solid raw material module may be a multilayer structure including: a core layer including the metal oxide; and a shell layer coated to surround the outer surface of the core layer, wherein the shell layer may include an alloy phase composed of metal M2 and metal M3.
- In one specific example embodiment, the solid raw material module may be configured to descend vertically within the cell until it reaches the liquid metal crucible through the flux, and the solid raw material module may descend at a rate of a distance corresponding to 0.1% to 10% of the depth of the cell per min.
- In one specific example embodiment, when the metal oxide is reduced to metal M1 by reaction with reducing metal M3 while the solid raw material module is melted, oxide M3 aOb may be produced, and the oxide M3 aOb may have a lower specific gravity than that of the flux. Here, a and b are each a real number ranging from 1 to 3.
- In one specific example embodiment, the oxide M3 aOb may float on the flux due to a density difference to form a by-product layer.
- In one specific example embodiment, as the process progresses, the liquid metal alloy may be continuously collected through the bottom of the cell, and the by-product layer may be continuously collected through the top of the cell, thereby enabling a continuous process.
- In one specific example embodiment, the system may further include a recycling part configured to collect the byproduct layer and mix the same with M1 xOz to produce M1 xM3 yOz.
- In one specific example embodiment, the reaction between the metal oxide and the reducing metal may be performed in an inert gas atmosphere and/or air.
- In one specific example embodiment, the core layer may be composed of a powder mixture including the metal oxide powder and the reducing metal M3 powder.
- In one specific example embodiment, the core layer may have a multilayer structure including: a first core composed of the metal oxide; and a second core coated to surround the outer surface of the first core and composed of metal M3.
- In one specific example embodiment, the solid raw material module may further include an oxidation-preventing layer surrounding the shell layer and serving to prevent oxidation of metal included in the core layer and/or the shell layer.
- In one specific example embodiment, the oxidation-preventing layer may include at least one selected from the group consisting of LiF, MgF2, CaF2, BaF2, CaCl2, MgCl2, MgO, CaO, BaO, Al2O3 and SiO2.
- In one specific example embodiment, metal M1 may be one selected from the group consisting of Ti, Zr, Hf, W, Fe, Ni, Zn, Co, Mn, Cr, Ta, Ga, Nb, Sn, Ag, La, Ce, Pr, Nd, Nb, Pm, Sm, Eu, Al, V, Mo, Gd, Tb, Dy, Ho, Er, Tm, Yb, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md and No, metal M2 may be at least one selected from the group consisting of Cu, Ni, Fe, Sn, Zn, Pb, Bi, Cd, and alloys thereof, and metal M3 may be at least one selected from the group consisting of Ca, Mg, Al, and alloys thereof.
- In one example embodiment of the present disclosure, a method of reducing and refining a metal oxide to metal M1 is provided.
- A method according to one example embodiment of the present disclosure may include: providing a cell; introducing a liquid flux into the cell; introducing metal M1 and metal M2 forming a eutectic phase with each other, thereby producing a liquid metal crucible having a specific gravity higher than that of the flux and accommodated in the cell while forming a layer under the flux without being mixed with the flux; moving a solid raw material module including a metal oxide, metal M2 and reducing metal M3 to the cell until it reaches the liquid metal crucible through the flux; and obtaining a liquid metal alloy including metal M1 derived from the metal oxide of the solid raw material module and metal M2.
- In one specific example embodiment, in the method, oxide M3 aOb may be produced as a by-product in moving the solid raw material module and/or obtaining the liquid metal alloy, and the oxide M3 aOb may have a lower specific gravity than that of the flux, and the method may further include continuously collecting the by-product M3 aOb forming a layer on the flux, and adding and mixing M1 xOz with the collected M3 aOb, thereby producing a metal oxide expressed as M1 xM3 yOz derived from the by-product M3 aOb and the added M1 xOz.
- In one example embodiment of the present disclosure, three is provided a metal alloy or metal produced by the method according to the above-described example embodiment, wherein the metal alloy may have a residual reducing metal M3 content of 0.1 wt % or less, specifically 0.01 wt % or less, more specifically 0.001 wt % or less, based on the total weight of the metal alloy, and an oxygen content of 1,200 ppm or less, specifically 1,000 ppm or less, more specifically 990 ppm or less.
- The present disclosure provides a system optimized for obtaining a desired metal from a metal oxide without using a metal chloride or using chloride as a flux, and a method for producing this metal. Accordingly, the present disclosure is capable of resolving the environmental problems of the above-described Kroll process and the cost problems caused by cell corrosion.
- The system and method provided in the present disclosure are characterized by using a liquid metal crucible that includes a liquid metal alloy of metal M1 and metal M2 forming a eutectic phase with each other. The use of such a liquid metal crucible may significantly reduce energy consumption, leading to cost reduction. This because when a metal oxide included in a module, which is a raw material, is reduced to metal M1, the melting point of metal M1 is lowered by a eutectic reaction so that electrolytic reduction may be effectively performed at a relatively low temperature.
- In addition, in the above system and method, a liquid alloy (M1 and M2 form a liquid metal alloy) is obtained by a eutectic reaction, and thus the metal alloy itself may be used as a final product. Since the final product derived from such a liquid alloy has a significantly smaller specific surface area that may be in contact with oxygen than the sponge-type product of the Kroll process, the system and method of the present disclosure may minimize the problem of oxygen contamination of the product.
- The liquid alloy thus obtained may be completely isolated from an environment in which oxygen may exist, and thus contamination thereof by oxygen may be significantly prevented. That is, according to the foregoing, it is possible to obtain a high-purity metal alloy and metal M1.
- In the system and method provided in the present disclosure, raw materials, for example, an oxide containing a desired metal, a reducing agent, and an alloying metal, form a module like a single part, and the system and method are characterized by using such a raw material module. In a process of continuously introducing a plurality of raw materials into a cell, like the Kroll process, the raw materials are likely to be oxidized or contaminated with oxygen before being introduced. However, the raw material module according to the present disclosure includes a structure treated to be prevented from oxidation, and thus has a more enhanced oxygen barrier effect compared to the Kroll process. Accordingly, the metal alloy and metal obtained according to the present disclosure may have a remarkably low oxygen content. In other words, according to the present disclosure, it is possible to obtain a high-purity metal alloy and metal having little oxygen.
-
FIG. 1 is a schematic view of a system according to one example embodiment of the present disclosure; -
FIG. 2 depicts photographs showing a process of preparing a raw material module including MgTiO3 as a metal oxide according to one example embodiment of the present disclosure; -
FIG. 3 is a graph showing the results of XRD analysis of the raw material module prepared as shown inFIG. 2 ; -
FIG. 4 is a schematic vertical sectional view of a raw material module according to one example embodiment of the present disclosure; -
FIG. 5 is a schematic vertical sectional view of a raw material module according to another example embodiment of the present disclosure; -
FIG. 6 is a schematic vertical sectional view of a raw material module according to still another example embodiment of the present disclosure; -
FIG. 7 is a photograph of a raw material module; -
FIG. 8 is another photograph of a raw material module; -
FIG. 9 depicts photographs showing the results of comparing weight before and after removing the flux from the alloy ingot produced in an Example; -
FIG. 10 is a table showing the results of performing elemental analysis of the inside of an alloy, produced in an Example, by energy dispersive spectrometry (EDS) after cutting the alloy; and -
FIG. 11 is a table showing the results of measuring the content of oxygen present in the alloy using ELTRA ONH2000. - Hereinafter, the intentions, operations and effects of the present disclosure will be described in detail through specific descriptions and examples to assist in understanding the example embodiments of the present disclosure and to implement these example embodiments. However, the following descriptions and example embodiments are presented as examples to assist in understanding the present disclosure as described above, and the scope of the invention is neither defined thereby nor limited thereto.
- Prior to the detailed description of the present disclosure, it should be noted that the terms or words used in the present specification and claims should not be construed as being limited to typical meanings or dictionary definitions, but should be interpreted as having meanings and concepts relevant to the technical scope of the present disclosure, based on the principle according to which the inventors can appropriately define the meaning of the terms to describe their invention in the best manner.
- Accordingly, it should be understood that the example embodiments described in the present specification and the configurations shown in the drawings are merely the most preferred example embodiments, but not cover all the technical spirits of the present disclosure, and thus there may be various equivalents and modifications capable of replacing them at the time of filing the present disclosure.
- In the present specification, singular expressions include plural expressions unless the context clearly indicates otherwise. In the present specification, it should be understood that terms such as “include” and “have” are intended to denote the existence of mentioned characteristics, numbers, operations, components, or combinations thereof, but do not exclude the possibility of existence or addition of one or more other characteristics, numbers, operations, components, or combinations thereof.
- The term “charging” as used in the present specification may be used interchangeably with the term “feeding”, “introducing”, “flowing in”, or “injection”, and may be understood to mean sending or putting any material, such as a raw material, into a place where it is needed.
- Hereinafter, the present disclosure will be described in detail in the order of a system for reduction to metal M1, a method for reduction to metal M1, and examples.
- In one specific example embodiment, a system for a metal oxide to metal M1 according to the present disclosure is schematically shown in
FIG. 1 . Referring toFIG. 1 , the system according to the present disclosure may include: acell 400; aliquid metal crucible 100 accommodated at the bottom of thecell 400 and including a liquid metal alloy of metal M1 and metal M2 forming a eutectic phase with each other; aliquid flux 200 accommodated in the cell while forming a layer on theliquid metal crucible 100 without being mixed with the liquid metal crucible, so as to block oxygen and reaction by-products from flowing into theliquid metal crucible 100; and a solidraw material module 300 including a metal oxide, metal M2, and reducing metal M3, wherein the metal oxide may be reduced to metal M1 by reaction with the reducing metal M3 while the solid raw material module reaches the liquid metal crucible and is melted, and the reduced metal M1 and metal M2 may be continuously incorporated into the liquid metal crucible while forming a liquid metal alloy. - In the system of the present disclosure, the desired metal M1 is not particularly limited, but may be specifically one selected from the group consisting of Ti, Zr, Hf, W, Fe, Ni, Zn, Co, Mn, Cr, Ta, Ga, Nb, Sn, Ag, La, Ce, Pr, Nd, Nb, Pm, Sm, Eu, Al, V, Mo, Gd, Tb, Dy, Ho, Er, Tm, Yb, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md and No. More specifically, the desired metal M1 may be one selected from the group consisting of Ti, Zr, W, Fe, Ni, Zn, Co, Mn, Cr, Ta, Er and No, and more specifically, may be one selected from the group consisting of Ti, Zr, W, Fe, Ni, Zn, Co, Mn, and Cr. Even more specifically, it may be Ti, Zr or W.
- In the system of the present disclosure, metal M2 is not particularly limited as long as it can form a liquid metal alloy by a eutectic reaction with metal M1. Specifically, metal M2 may be at least one selected from the group consisting of Cu, Ni, Fe, Sn, Zn, Pb, Bi, Cd, and alloys thereof, and more specifically, may be Cu, Ni, or an alloy thereof.
- In the system of the present disclosure, metal M3 is not particularly limited as long as it can reduce the metal oxide to M1. Specifically, metal M3 may be at least one selected from among Ca, Mg, Al, and alloys thereof, and more specifically, may be Ca or Mg, in particular, Mg.
- In the system of the present disclosure, the metal oxide may include at least one selected from the group consisting of M1 xOz and M1 xM3 yOz, wherein x and y are each a real number ranging from 1 to 3, and z is a real number ranging from 1 to 4.
- In one specific example embodiment, the metal oxide may include one or a combination of two or more selected from the group consisting of ZrO2, TiO2, MgTiO3, HfO2, Nb2O5, Dy2O3, Tb4O7, WO3, Co3O4, MnO, Cr2O3, MgO, CaO, Al2O3, Ta2O5, Ga2O3, Pb3O4, SnO, NbO and Ag2O, without being limited thereto.
- The system according to the present disclosure is different from the conventional Kroll process in that it uses a metal oxide instead of a metal chloride as a raw material. Raw materials usually found in nature include an oxide of metal M1, and in order to use this metal oxide in the Kroll process, a pretreatment process of substituting the metal oxide with a chloride needs to be performed. If this pretreatment process is performed, it itself will cause an increase in process cost. Moreover, hydrochloric acid is used in the pretreatment process of substituting the metal oxide with a chloride, and in this case, corrosion of production equipment may be promoted due to the strong acidity of the hydrochloric acid, and toxic chlorine gas may be generated during the process, which may cause environmental problems. The system according to the present disclosure has advantages over the Kroll process in that it does not require the pretreatment process of substituting the metal oxide with a chloride, and thus it incurs a lower cost than the Kroll process cost and does not cause environmental problems.
- The
cell 400 is preferably made of a material that has a high melting point in terms of durability and does not cause side reactions with the flux and the liquid metal crucible. The material of the cell may include at least one selected from the group consisting of MgO, Cr2O3, Al2O3, SiO2, CaO, SiC, WO3, W, C, and Mo, without being limited thereto. - The
cell 400 may include atapping hole 410 for continuously tapping the liquid metal alloy produced at the bottom thereof. - As used herein, the term “liquid metal crucible” may refer to a reaction region capable of providing an environment in which at least one metal may be accommodated in, for example, the cell in a molten state while forming one layer, and the raw material module of the present disclosure may be melted within and the layer surface of the melted metal so that the metal oxide may be reduced.
- The system according to the present disclosure has the advantage of using this liquid metal crucible.
- Specifically, in the system of the present disclosure, as the liquid metal crucible including the liquid metal alloy of metal M1 and metal M2 forming a eutectic phase with each other is used, melting point of metal M1 may be lowered by the eutectic reaction while the metal oxide of the raw material module is reduced to metal M1, and thus electrolytic reduction may be effectively performed at a relatively low temperature. That is, in the system of the present disclosure, it is possible to obtain a liquid metal alloy while operating a liquid metal crucible in which metals are melted, and it is possible to operate the process at a lower temperature than the melting point of metal M1, thereby significantly reducing energy consumption. This temperature may vary depending on the types of M1 and M2, but may preferably be 900° C. to 1,600° C.
- What is also noteworthy about the liquid metal crucible is that a liquid alloy (M1 and M2 form a liquid metal alloy) may be obtained based on the eutectic reaction induced in the system of the present disclosure, and the metal alloy itself may be used as a final product. M1 is often used industrially in the form of an alloy. When M1 can be produced as only a single metal as in the conventional Kroll process, a post-processing process for forming an alloy with another metal may be required. However, the present disclosure has high process efficiency in that it is possible to obtain a final product in the form of a metal alloy of M1 and M2 through reduction reaction without the above-described post-treatment process. In addition, when the liquid metal crucible is formed, there are advantages in that it is possible to adjust the ratio between M1 and M2, it is also possible to adjust the ratio between the metal oxide and M2 in the module, and thus it is possible to the ratio between M1 and M2 in the metal alloy as a final product. It is to be understood that, if necessary, metal M1 may be obtained by electrorefining the obtained metal alloy, and a method known in the art may be used for such electrolytic refining.
- The liquid alloy obtained according to the present disclosure may be completely isolated from an environment in which oxygen may exist, and thus contamination thereof by oxygen may be significantly prevented. That is, according to the above aspect, it is possible to obtain a high-purity metal alloy and metal M1.
- Furthermore, the use of the liquid metal crucible including the liquid metal alloy of metal M1 and metal M2 forming a eutectic phase with each other has an advantage in that, even if the metal oxide contained in the raw material module is a material that is difficult to electrolytically reduce to metal, it is possible to more easily reduce the metal oxide in the raw material module using the standard oxidation-reduction potential difference between the liquid metal alloy and the desired metal M1. That is, when metal M2 having a more positive standard reduction potential that of metal M1 is used, the standard reduction potential value of M1 may move in a positive direction due to the liquid metal crucible, so that electrolytic reduction of the metal may be more easily achieved.
- In one major aspect of the present disclosure, in the system of the present disclosure, a metal oxide as a raw material, another metal as a reducing agent, and other additive metals are not introduced, but they constitute a raw material module like a single part, and based on this raw material module, it is possible to obtain a higher-quality metal alloy and metal.
- For example, in a process of continuously introducing a plurality of raw materials into a cell, like the Kroll process, the raw materials are likely to be oxidized before being introduced, but the raw material module according to the present disclosure includes a structure treated to be prevented from oxidation, and thus has a more enhanced oxygen barrier effect compared to the Kroll process. Accordingly, the metal alloy and metal obtained according to the present disclosure may have a significantly low oxygen content.
- Additionally, as described above, the system of the present disclosure includes a configuration for doubly blocking oxygen, because the flux serves as a barrier layer for blocking oxygen, and the raw material module itself can also block oxygen. Accordingly, the system of the present disclosure has significant advantages in that it is possible to perform the reaction between the metal oxide and the reducing metal under an inert gas atmosphere, which has been commonly recognized in the art, and it is also possible to perform the reaction between the metal oxide and the reducing metal in air. Even if the system of the present disclosure is operated in air, the metal alloy and metal produced thereby are of high purity with little oxygen. This will be clearly demonstrated through examples to be described later. In some cases, in the system of the present disclosure, the reaction between the metal oxide and the reducing metal may be performed in a combination of an inert gas atmosphere and a normal air atmosphere.
- In addition, the system of the present disclosure uses a raw material module in which raw materials necessary for the reaction are gathered into one body, and thus has an advantage in that it is easy to induce the reaction at the most optimal location in the cell.
- Photographs showing a process of preparing a raw material module according to the present disclosure are depicted in
FIG. 2 , andFIG. 4 shows a schematic view of a raw material module according to one example embodiment of the present disclosure. Incidentally, the photographs shown inFIG. 2 are only for helping understanding of the preparation of the raw material module as a non-limiting example, and the scope of the present disclosure is not limited thereto. - Referring to
FIG. 4 , the solidraw material module 300 may include: acore layer 30 including themetal oxide 10 and the reducingmetal M 3 30; and ashell layer 320 composed of metal M2 surrounding thecore layer 310. As shown inFIG. 4 , thecore layer 310 may have a multilayer structure including: afirst core 311 composed of themetal oxide 10; and asecond core 312 coated to surround the outer surface of thefirst core 311 and composed of the reducingmetal M 3 30. - In some cases, a
raw material module 300 a as shown inFIG. 5 in which a core layer is shown as another example of the present disclosure may be used. Thecore layer 310 a of theraw material module 300 a may be composed of a powdery mixture includingmetal oxide powder 10 a and reducing metal M3 powder 30 a. - Alternatively, the structure shown in
FIG. 6 may also be preferable as the raw material module. Referring toFIG. 6 , theraw material module 300 b is similar to the above-described example in terms of a multilayer structure, but is different from the above-described example in that it includes thecore layer 310 b including themetal oxide 10 b and theshell layer 320 b coated to surround the outer surface of thecore layer 310 b, wherein theshell layer 320 b is a coating layer including analloy phase 330 b composed of themetal M 2 20 b and themetal M 3 30 b. - The above-described solid raw material module may further include an oxidation-preventing layer (330 in
FIG. 4 ) surrounding the shell layer and serving to prevent oxidation of metal included in the core layer and/or the shell layer by blocking oxygen from contacting the metal. The oxidation-preventinglayer 330 may include at least one selected from the group consisting of LiF, MgF2, CaF2, BaF2, CaCl2, MgCl2, MgO, CaO, BaO, Al2O3 and SiO2, but the scope of the present disclosure is not limited thereto. Although the oxidation-preventing layer is shown only inFIG. 4 , it is to be understood that the oxidation-preventing layer may also be applied to the other example embodiments shown inFIGS. 5 and 6 . - This solid raw material module may be configured to descend vertically within the cell until it reaches the liquid metal crucible through the flux. The solid raw material module may descend at a rate of a distance corresponding to 0.1% to 10% of the depth of the cell per min.
- When the descending direction of the solid raw material module is set as an imaginary axis, rotating the solid raw material module about the axis is preferable in terms of stirring the liquid metal crucible and improving reactivity thereby. The rotation may be performed during the descent into the cell and/or until completion of the descent.
- Accordingly, the system according to the present disclosure may further include a rotation unit to which the solid raw material module is mounted and which rotates the same.
- Meanwhile, the solid raw material module descends to the liquid metal crucible and is melted, and at the same time or partially simultaneously, the metal oxide and the reducing metal M3 react to reduce the metal oxide to M1, and the reduced M1 forms a liquid metal alloy with M2 contained in the solid raw material module.
- As an example, when M1 is Ti, the metal oxide (M1 xOz) is TiO2, M2 is Ni, and M3 is Mg, according to Reaction Formulas 1-1 and 1-2 below, the metal oxide may be reduced to metal Ti, and then an M3 oxide (M3 aOb) may be separated while the liquid metal alloy TiNi is obtained.
-
2Mg+TiO2->Ti+2MgO [Reaction Formula 1-1] -
Ti+Ni+2MgO→TiNi (alloy)+2MgO (separated) [Reaction Formula 1-2] - As another example, when M1 is Ti, the metal oxide (M1 xM3 yOz) is MgTiO3, M2 is Ni, and M3 is Mg, according to Reaction Formulas 2-1 and 2-2 below, the metal oxide may be reduced to metal Ti, and then an M3 oxide (M3 aOb) may be separated while the liquid metal alloy TiNi is obtained.
-
2Mg+MgTiO3->Ti+3MgO [Reaction Formula 2-1] -
Ti+Ni+3MgO→TiNi (alloy)+3MgO (separated) [Reaction Formula 2-2] - M3aOb produced according to the above-described reaction is a kind of by-product and may have a lower specific gravity that that of the flux of the present disclosure. The M3 aOb may float on the flux due to its density difference from the flux to form a by-product layer. Therefore, the by-product M3 aOb does not mix with the liquid metal crucible present as a layer under the flux and with the formed liquid metal alloy. In addition, the by-product layer may serve to prevent the flux from being lost by vaporization while being positioned on the flux, and to prevent oxygen in the air from penetrating into the reactor.
- Meanwhile, since the by-product floats on the cell as the liquid metal alloy is produced, the by-product needs to be continuously removed from the cell in order to continuously perform the process in the cell having a limited volume. Thus, the system according to the present disclosure may be configured to enable a continuous process by using this by-product. Specifically, the system of the present disclosure may further include a recycling device that continuously collects the layered by-product floating on the flux through the top of the cell and mixes the collected by-product with, for example, M1 xOz to produce metal oxide M1 xM3 yOz. At this time, when the produced M1 xM3 yOz is used, the reduction reaction rate may be further increased compared to when M1 xOz is used.
- The flux preferably has a specific gravity which is intermediate between the specific gravity of the liquid metal crucible and the specific gravity of the by-product M3 aOb so as to prevent the liquid metal crucible and the by-product M3 aOb from mixing with each other, and at the same time, the flux is preferably insoluble in the by-product M3 aOb. The flux is preferably a material such as a non-chlorine-based material, which does not cause environmental problems while being capable of preventing prevent oxygen from penetrating into the liquid metal crucible and the liquid metal alloy containing the desired metal M1.
- This flux may include a molten halide salt of at least one metal selected from the group consisting of alkali metals and alkaline earth metals, but does not contain chloride. More specifically, the flux in the system of the present disclosure may be a molten halide salt of at least one metal selected from the group consisting of alkali metals including Li, Na, K, Rb, and Cs, and alkaline earth metals including Mg, Ca, Sr, and Ba. In this case, the halide may include fluoride, bromide, iodide, or a mixture thereof.
- In the system of the present disclosure, the flux may also be present in an amount of 10 wt % to 50 wt %, specifically 10 wt % to 20 wt %, more specifically 10 wt % to 15 wt %, even more specifically 12 wt % to 13 wt %, relative to the metal oxide involved in the overall reduction reaction, that is, the metal oxide contained in the raw material module and capable of being reduced to the desired metal M1.
- The flux may further contain, as an additive, at least one metal oxide selected from the group of alkali metals and alkaline earth metals. The content of the additive may be 0.1 to 25 wt % based on the total weight of the flux. The additive may include Li2O, Na2O, SrO, Cs2O, K2O, CaO, BaO, or a mixture thereof, without being limited thereto. The additive contained in the flux may enable easier reduction of the metal oxide contained in the raw material module.
- The system according to the present disclosure may further include an electrorefining part configured to continuously collect the liquid metal alloy formed by M1 and M2 through the bottom of the cell and to electrorefine the collected liquid metal alloy to obtain metal M1.
- The electrorefining part may solidify the collected liquid metal alloy to obtain a solid metal alloy, and electrorefine the solid metal alloy, thereby recovering metal M1 from the metal alloy.
- In some cases, a flux that may remain in the liquid metal alloy may be removed before electrorefining of the solid metal alloy, and this removal may be achieved, for example, by heat-treating the liquid metal alloy in a vacuum or inert gas atmosphere, causing the flux to be removed by distillation. The distillation temperature (heat treatment temperature) is not particularly limited as long as it is a temperature equal to or higher than the melting point of the flux used in the system of the present disclosure, and it may be, for example, 780 to 1,000° C. In order to effectively prevent the liquid metal alloy from being oxidized again, it may be advantageous to carry out the distillation in a vacuum atmosphere and under an inert gas atmosphere.
- The electrorefining part may include a flux including a molten halide salt of at least one metal selected from the group consisting of alkali metals and alkaline earth metals, independently of the flux used in the above-described reduction reaction.
- The method according to the present disclosure may include the operations of: providing a cell; introducing a liquid flux into the cell; introducing metal M1 and metal M2 forming a eutectic phase with each other, thereby producing a liquid metal crucible having a specific gravity higher than that of the flux and accommodated in the cell while forming a layer under the flux without being mixed with the flux; moving a solid raw material module including a metal oxide, metal M2 and reducing metal M3 to the cell until it reaches the liquid metal crucible through the flux; and obtaining a liquid metal alloy including metal M1 derived from the metal oxide of the solid raw material module and metal M2.
- In the operation of moving the solid raw material module, when the solid raw material module is melted when it reaches the liquid metal crucible. In this case, the metal oxide and the reducing metal M3 may react with each other to reduce the metal oxide to metal M1, and the reduced metal M1 and metal M2 may be continuously incorporated into the liquid metal crucible while forming a liquid metal alloy.
- In the method of the present disclosure, the desired metal M1 is not particularly limited, but may be specifically one selected from the group consisting of Ti, Zr, Hf, W, Fe, Ni, Zn, Co, Mn, Cr, Ta, Ga, Nb, Sn, Ag, La, Ce, Pr, Nd, Nb, Pm, Sm, Eu, Al, V, Mo, Gd, Tb, Dy, Ho, Er, Tm, Yb, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md and No. More specifically, the desired metal M1 may be one selected from the group consisting of Ti, Zr, W, Fe, Ni, Zn, Co, Mn, Cr, Ta, Er and No, and more specifically, may be one selected from the group consisting of Ti, Zr, W, Fe, Ni, Zn, Co, Mn, and Cr. Even more specifically, it may be Ti, Zr or W.
- In the method of the present disclosure, metal M2 is not particularly limited as long as it can form a liquid metal alloy by a eutectic reaction with metal M1. Specifically, metal M2 may be at least one selected from the group consisting of Cu, Ni, Fe, Sn, Zn, Pb, Bi, Cd, and alloys thereof, and more specifically, may be Cu, Ni, or an alloy thereof.
- In the method of the present disclosure, metal M3 is not particularly limited as long as it can reduce the metal oxide to M1. Specifically, metal M3 may be at least one selected from among Ca, Mg, Al, and alloys thereof, and more specifically, may be Ca or Mg, in particular, Mg.
- In the method of the present disclosure, the metal oxide may include at least one selected from the group consisting of M1 xOz and M1 xM3 yOz, wherein x and y are each a real number ranging from 1 to 3, and z is a real number ranging from 1 to 4.
- In one specific example embodiment, the metal oxide may include one or a combination of two or more selected from the group consisting of ZrO2, TiO2, MgTiO3, HfO2, Nb2O5, Dy2O3, Tb4O7, WO3, Co3O4, MnO, Cr2O3, MgO, CaO, Al2O3, Ta2O5, Ga2O3, Pb3O4, SnO, NbO and Ag2O, without being limited thereto.
- The method according to the present disclosure is different from the conventional Kroll process in that it uses a metal oxide instead of a metal chloride as a raw material. Raw materials usually found in nature include an oxide of metal M1, and in order to use this metal oxide in the Kroll process, a pretreatment process of substituting the metal oxide with a chloride needs to be performed. If this pretreatment process is performed, it itself will cause an increase in process cost. Moreover, hydrochloric acid is used in the pretreatment process of substituting the metal oxide with a chloride, and in this case, corrosion of production equipment may be promoted due to the strong acidity of the hydrochloric acid, and toxic chlorine gas may be generated during the process, which may cause environmental problems. The method according to the present disclosure has advantages over the Kroll process in that it does not require the pretreatment process of substituting the metal oxide with a chloride, and thus it incurs a lower cost than the Kroll process cost and does not cause environmental problems.
- The raw material module that is used in the method of the present disclosure may include: a core layer including a metal oxide and reducing metal M3; and a shell layer composed of metal M2 surrounding the core layer. As shown in
FIG. 4 , thecore layer 310 may have a multilayer structure including: a first core composed of the metal oxide; and a second core coated to surround the outer surface of the first core and composed of the reducing metal M3. In some cases, as shown inFIG. 5 in which a core layer is shown as another example of the present disclosure. Thecore layer 310 a of theraw material module 300 a may be composed of a powdery mixture including metal oxide powder and reducing metal M3 powder. - Alternatively, the raw material module shown in
FIG. 6 may also be used. This raw material module may include the core layer including the metal oxide and the shell layer coated to surround the outer surface of the core layer, wherein the shell layer may be a coating layer including an alloy phase composed of metal M2 and metal M3. - The solid raw material module may further include an oxidation-preventing layer surrounding the shell layer and serving to prevent oxidation of metal included in the core layer and/or the shell layer by blocking oxygen from contacting the metal. The oxidation-preventing layer may include at least one selected from the group consisting of LiF, MgF2, CaF2, BaF2, CaCl2, MgCl2, MgO, CaO, BaO, Al2O3 and SiO2, but the scope of the present disclosure is not limited thereto.
- In the operation of moving the solid raw material module, the solid raw material module may be descended at a rate of a distance corresponding to 0.1% to 10% of the depth of the cell per min, until it reaches the liquid metal crucible through the flux.
- In the operation of obtaining a liquid metal alloy including metals M1 and M2, when the solid raw material module reaches the liquid metal crucible and is melted, the metal oxide may be reduced to metal M1 by reaction with the reducing metal M3, and the reduced M1 may form a liquid metal alloy with the metal M2 contained in the solid raw material module.
- As an example, when M1 is Ti, the metal oxide (M1 xOz) is TiO2, M2 is Ni, and M3 is Mg, according to Reaction Formulas 1-1 and 1-2 below, the metal oxide may be reduced to metal Ti, and then an M3 oxide (M3 aOb) may be separated while the liquid metal alloy TiNi is obtained.
-
2Mg+TiO2->Ti+2MgO [Reaction Formula 1-1] -
Ti+Ni+2MgO→TiNi (alloy)+2MgO (separated) [Reaction Formula 1-2] - As another example, when M1 is Ti, the metal oxide (M1 xM3 yOz) is MgTiO3, M2 is Ni, and M3 is Mg, according to Reaction Formulas 2-1 and 2-2 below, the metal oxide may be reduced to metal Ti, and then an M3 oxide (M3 aOb) may be separated while the liquid metal alloy TiNi is obtained.
-
2Mg+MgTiO3->Ti+3MgO [Reaction Formula 2-1] -
Ti+Ni+3MgO→TiNi (alloy)+3MgO (separated) [Reaction Formula 2-2] - M3aOb produced according to the above-described reaction is a kind of by-product and may have a lower specific gravity that that of the flux of the present disclosure. The M3 aOb may float on the flux due to its density difference from the flux to form a by-product layer. Therefore, the by-product M3 aOb does not mix with the liquid metal crucible present as a layer under the flux and with the formed liquid metal alloy. In addition, the by-product layer may serve to prevent the flux from being lost by vaporization while being positioned on the flux, and to prevent oxygen in the air from penetrating into the reactor.
- Meanwhile, since the by-product floats on the cell as the liquid metal alloy is produced, the by-product needs to be continuously removed from the cell in order to continuously perform the process in the cell having a limited volume. Thus, the method according to the present disclosure may be configured to use this by-product. Specifically, the method according to the present disclosure may further include the operation of continuously collecting the layered by-product (i.e., M3 aOb) floating on the flux through the top of the cell, and adding and mixing, for example, M1 xOz with the collected M3 aOb, thereby producing the metal oxide M1 xM3 yOz derived from the by-product M3 aOb and the added M1 xOz.
- When M1 xM3 yOz obtained as described above is used, in some cases, the reduction reaction rate may be further increased compared to when M1 xOz is used. The operation of producing M1 xM3 yOz may be performed at a temperature of 1,000° C. to 1,500° C., specifically 1,200° C. to 1,400° C., more specifically, 1,250° C. to 1,350° C.
- The type of the flux is not particularly limited unless it is a chlorine-based material, and is preferably as defined in the previous example embodiment.
- The method according to the present disclosure may further include, after the operation of obtaining the alloy including metals M1 and M2, the operation of obtaining metal M1 by electrorefining the obtained alloy.
- The operation of obtaining metal M1 by electrorefining may be the operation of solidifying the obtained liquid metal alloy to obtain a solid alloy, and electrorefining the solid alloy, thereby recovering metal M1 from the alloy.
- Hereinafter, example will be described in detail with reference to
FIGS. 3 to 5 and 6 a to 6 c, whereby the action and effect of the present disclosure will be demonstrated. However, the following examples are only presented as examples of the present disclosure, and the scope of the present disclosure is not defined thereby. - The system shown in
FIG. 1 was used. Flux MgF2 (0.2 kg)-BaF2 (1.5 kg) in a resistance heating furnace was weighed, introduced into a cell, and then heated to about 1,200° C. to form a flux layer. - Cu (20 g) and Ti (200 g) were weighed, introduced into the cell, and melted, thereby producing a liquid metal crucible positioned at the bottom of the cell and forming a layer under the flux.
- As shown in
FIG. 2 , 630 g of MgTiO3 (average particle size of 300 μm) as a metal oxide and 250 g of Mg powder as metal M3 were mixed together, charged into a cylindrical copper container (250 g), and dried, thus preparing a raw material module. Incidentally, photographs of the actually prepared raw material module are shown inFIGS. 7 and 8 . - The prepared raw material module was charged into the cell and descended vertically at a rate of about 6 cm/min until it reached the layer of the liquid metal crucible. At this time, the module was rotated for 10 minutes to stir the flux and the liquid metal crucible. The melting and reduction reaction of the raw material module was performed for 2 hours, and a CuTi liquid metal alloy as a reaction product was collected through an outlet provided at the bottom of the cell and was solidified to finally obtain a CuTi alloy shown in
FIG. 9 . In addition, after completion of the reaction, the crucible was cooled at a rate of −10° C./min to prevent damage to the crucible. - The properties of the alloy obtained in Example 1 were evaluated using the following methods.
-
- Recovery: 100−{(first weight−second weight)/second weight×100%}
- Residual impurity content: the produced alloy was cut and the inside of the alloy was analyzed by energy dispersive spectrometry.
- Oxygen content: the oxygen content in the alloy was measured using an ELTRA ONH2000.
-
TABLE 1 Energy dispersive First Second Recov- spectrometry results Oxygen weight* weight** ery Ti Cu content (g) (g) (%) (wt %) (wt %) (ppm) Example 500 488.56 97.7% 40.29 59.71 980.35 *First weight: total weight of liquid metal crucible of CuTi initially charged into cell + stoichiometric reduction amount of Ti contained in metal oxide **Second weight: total weight of CuTi obtained - From the results in Table 1 above, it can be seen that the alloy of the Example, produced according to the present disclosure, exhibited a high recovery rate which is much higher than 90%, and contained oxygen as a contaminant at an extremely low level. The results for this low oxygen content are clearly demonstrated in
FIG. 11 . - In addition,
FIG. 10 shows the results obtained by cutting the alloy produced in the Example and analyzing the residual impurity content in the inside of the alloy by energy dispersion spectrometry. Referring toFIG. 10 , it can be seen that the alloy is composed only of the desired metal Ti and Cu, and Mg used as the reducing metal does not exist at all. - These experimental results suggest that, according to the present disclosure, it is possible to obtain a high-purity alloy which has a very low oxygen content and has no other impurities used in the process.
- The various embodiments described above can be combined to provide further embodiments. All of the U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet are incorporated herein by reference, in their entirety. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, applications, and publications to provide yet further embodiments.
- These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.
Claims (23)
1. A system for reducing a metal oxide to metal M1, the system comprising:
a cell;
a liquid metal crucible accommodated at a bottom of the cell and comprising a liquid metal alloy of metal M1 and metal M2 forming a eutectic phase with each other;
a liquid flux accommodated in the cell while forming a layer on the liquid metal crucible without being mixed with the liquid metal crucible; and
a solid raw material module comprising a metal oxide, metal M2, and reducing metal M3,
wherein the metal oxide is reduced to metal M1 by reaction with the reducing metal M3 while the solid raw material module reaches the liquid metal crucible and is melted, and the reduced metal M1 and the metal M2 are continuously incorporated into the liquid metal crucible while forming a liquid metal alloy.
2. The system according to claim 1 , further comprising an electrorefining part configured to collect and electrorefine the liquid metal alloy formed by the reduced metal M1 and the metal M2 to obtain metal M1.
3. The system according to claim 1 , wherein the metal oxide comprises at least one selected from the group consisting of M1 xOz and M1 xM3 yOz, wherein x and y are each a real number ranging from 1 to 3, and z is a real number ranging from 1 to 4.
4. The system according to claim 1 , wherein the solid raw material module comprises: a core layer comprising the metal oxide and the reducing metal M3; and a shell layer composed of metal M2 surrounding the core layer.
5. The system according to claim 1 , wherein:
the solid raw material module is a multilayer structure comprising: a core layer comprising the metal oxide; and a shell layer coated to surround an outer surface of the core layer; and
the shell layer comprises an alloy phase composed of the metal M2 and the metal M3.
6. The system according to claim 1 , wherein:
the solid raw material module is configured to descend vertically within the cell until it reaches the liquid metal crucible through the flux; and
the solid raw material module descends at a rate of a distance corresponding to 0.1% to 10% of a depth of the cell per min.
7. The system according to claim 1 , wherein, when the metal oxide is reduced to the metal M1 by reaction with the reducing metal M3 while the solid raw material module is melted, oxide M3 aOb is produced, and the oxide M3 aOb has a lower specific gravity than that of the flux, wherein a and b are each a real number ranging from 1 to 3.
8.-10. (canceled)
11. The system according to claim 1 , wherein the reaction between the metal oxide and the reducing metal is performed in an inert gas atmosphere and/or air.
12. The system according to claim 4 , wherein the core layer is composed of a powder mixture comprising powder of the metal oxide powder and powder of the reducing metal M3.
13. The system according to claim 4 , wherein the core layer is a multilayer structure comprising: a first core composed of the metal oxide; and a second core coated to surround an outer surface of the first core and composed of the metal M3.
14. The system according to claim 4 , wherein the solid raw material module further comprises an oxidation-preventing layer surrounding the shell layer and serving to prevent oxidation of the metal contained in the core layer and/or the shell layer.
15. (canceled)
16. The system according to claim 1 , wherein the metal M1 is one selected from the group consisting of Ti, Zr, Hf, W, Fe, Ni, Zn, Co, Mn, Cr, Ta, Ga, Nb, Sn, Ag, La, Ce, Pr, Nd, Nb, Pm, Sm, Eu, Al, V, Mo, Gd, Tb, Dy, Ho, Er, Tm, Yb, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md and No.
17. The system according to claim 1 , wherein the metal M2 is at least one selected from the group consisting of Cu, Ni, Fe, Sn, Zn, Pb, Bi, Cd, and alloys thereof.
18. The system according to claim 1 , wherein the metal M3 is at least one selected from the group consisting of Ca, Mg, Al, and alloys thereof.
19. The system according to claim 1 , wherein the flux comprises a molten halide salt of at least one metal selected from the group consisting of alkali metals and alkaline earth metals.
20. A method of reducing a metal oxide to metal M1, the method comprising:
providing a cell;
introducing a liquid flux into the cell;
introducing metal M1 and metal M2 forming a eutectic phase with each other, thereby producing a liquid metal crucible having a specific gravity higher than that of the flux and accommodated in the cell while forming a layer under the flux without being mixed with the flux;
moving a solid raw material module comprising a metal oxide, metal M2 and reducing metal M3 to the cell until it reaches the liquid metal crucible through the flux; and
obtaining a liquid metal alloy comprising metal M1 derived from the metal oxide of the solid raw material module and metal M2.
21. The method according to claim 20 , further comprising obtaining metal M1 by electrorefining the obtained metal alloy comprising the metals M1 and M2.
22. The method according to claim 20 , wherein oxide M3 aOb is produced as a by-product in moving the solid raw material module and/or obtaining the liquid metal alloy, and the oxide M3 aOb has a lower specific gravity than that of the flux, and
the method further comprises continuously collecting the by-product M3 aOb forming a layer on the flux, and adding and mixing M1 xOz with the collected M3 aOb, thereby producing a metal oxide expressed as M1 xM3 yOz derived from the by-product M3 aOb and the added M1 xOz.
23. A metal alloy obtained by the method according to claim 20 .
24. A metal obtained by the method according to claim 21 .
25. (canceled)
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