WO2022109725A1 - Removing impurities from an electrolyte - Google Patents
Removing impurities from an electrolyte Download PDFInfo
- Publication number
- WO2022109725A1 WO2022109725A1 PCT/CA2021/051665 CA2021051665W WO2022109725A1 WO 2022109725 A1 WO2022109725 A1 WO 2022109725A1 CA 2021051665 W CA2021051665 W CA 2021051665W WO 2022109725 A1 WO2022109725 A1 WO 2022109725A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- cathodes
- anodes
- bath
- purifier assembly
- anode
- Prior art date
Links
- 239000012535 impurity Substances 0.000 title claims abstract description 40
- 239000003792 electrolyte Substances 0.000 title description 15
- 238000000746 purification Methods 0.000 claims abstract description 58
- 238000000034 method Methods 0.000 claims abstract description 39
- 229910052751 metal Inorganic materials 0.000 claims abstract description 25
- 239000002184 metal Substances 0.000 claims abstract description 25
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 21
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 20
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 20
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 12
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims abstract description 11
- 229910052742 iron Inorganic materials 0.000 claims abstract description 11
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 11
- 239000011593 sulfur Substances 0.000 claims abstract description 11
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 10
- 229910052733 gallium Inorganic materials 0.000 claims abstract description 10
- 239000011574 phosphorus Substances 0.000 claims abstract description 10
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 claims abstract description 9
- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 9
- 229910001610 cryolite Inorganic materials 0.000 claims abstract description 8
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 17
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 16
- 229910000831 Steel Inorganic materials 0.000 claims description 14
- 229910052802 copper Inorganic materials 0.000 claims description 14
- 239000010949 copper Substances 0.000 claims description 14
- 239000010959 steel Substances 0.000 claims description 14
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 12
- 238000005260 corrosion Methods 0.000 claims description 9
- 230000007797 corrosion Effects 0.000 claims description 9
- 229910052759 nickel Inorganic materials 0.000 claims description 9
- 229910052799 carbon Inorganic materials 0.000 claims description 8
- 229910002804 graphite Inorganic materials 0.000 claims description 8
- 239000010439 graphite Substances 0.000 claims description 8
- 238000002844 melting Methods 0.000 claims description 8
- 230000008018 melting Effects 0.000 claims description 8
- 229910044991 metal oxide Inorganic materials 0.000 claims description 8
- 150000004706 metal oxides Chemical class 0.000 claims description 8
- PUZPDOWCWNUUKD-UHFFFAOYSA-M sodium fluoride Chemical compound [F-].[Na+] PUZPDOWCWNUUKD-UHFFFAOYSA-M 0.000 claims description 8
- 229910001220 stainless steel Inorganic materials 0.000 claims description 8
- 239000000654 additive Substances 0.000 claims description 7
- 229910052804 chromium Inorganic materials 0.000 claims description 7
- 239000011651 chromium Substances 0.000 claims description 7
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 7
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- 239000007787 solid Substances 0.000 claims description 6
- 239000010935 stainless steel Substances 0.000 claims description 6
- IRPGOXJVTQTAAN-UHFFFAOYSA-N 2,2,3,3,3-pentafluoropropanal Chemical compound FC(F)(F)C(F)(F)C=O IRPGOXJVTQTAAN-UHFFFAOYSA-N 0.000 claims description 4
- KLZUFWVZNOTSEM-UHFFFAOYSA-K Aluminum fluoride Inorganic materials F[Al](F)F KLZUFWVZNOTSEM-UHFFFAOYSA-K 0.000 claims description 4
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims description 4
- 229910001634 calcium fluoride Inorganic materials 0.000 claims description 4
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 4
- 235000013024 sodium fluoride Nutrition 0.000 claims description 4
- 239000011775 sodium fluoride Substances 0.000 claims description 4
- 238000009413 insulation Methods 0.000 claims description 3
- 229910000510 noble metal Inorganic materials 0.000 claims description 3
- 230000001681 protective effect Effects 0.000 claims description 2
- 230000003014 reinforcing effect Effects 0.000 claims description 2
- 230000000087 stabilizing effect Effects 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 abstract description 9
- 239000004411 aluminium Substances 0.000 abstract description 3
- 239000007789 gas Substances 0.000 description 11
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 9
- 239000000463 material Substances 0.000 description 9
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 6
- 238000005868 electrolysis reaction Methods 0.000 description 6
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 239000003575 carbonaceous material Substances 0.000 description 2
- JJWKPURADFRFRB-UHFFFAOYSA-N carbonyl sulfide Chemical compound O=C=S JJWKPURADFRFRB-UHFFFAOYSA-N 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 229910010271 silicon carbide Inorganic materials 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 238000009626 Hall-Héroult process Methods 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 1
- 239000012774 insulation material Substances 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000013341 scale-up Methods 0.000 description 1
- 238000007790 scraping Methods 0.000 description 1
- 230000001131 transforming effect Effects 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B1/00—Electrolytic production of inorganic compounds or non-metals
- C25B1/01—Products
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/02—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B15/00—Operating or servicing cells
- C25B15/04—Regulation of the inter-electrode distance
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
- C25B9/30—Cells comprising movable electrodes, e.g. rotary electrodes; Assemblies of constructional parts thereof
-
- 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
- C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
- C25C3/18—Electrolytes
-
- 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
-
- 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
- C25C7/005—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells of cells for the electrolysis of melts
-
- 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
- C25C7/007—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells of cells comprising at least a movable electrode
-
- 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
- C25C7/02—Electrodes; Connections thereof
- C25C7/025—Electrodes; Connections thereof used in cells for the electrolysis of melts
Definitions
- the present patent application generally relates to the purification of a molten electrolytic bath of an electrolytic cell, the electrolytic cell being used, for instance, for the production of a metal, such as aluminum.
- Aluminum metal also called aluminium
- alumina also known as aluminium oxide (IUPAC)
- IUPAC aluminium oxide
- the cells have a crucible comprising a steel shell, containing a carbonaceous cathode material, steel current conducting bars and refractory insulation materials capable of containing the electrolyte, at least one cathode and at least one anode.
- the direct current that passes through the anodes, the electrolyte and cathodes causes alumina reduction reactions, and is also capable of maintaining the electrolytic bath at the target operating temperature by the Joule effect.
- the electrolysis cell is regularly supplied with alumina so as to compensate for consumption of alumina caused by electrolysis reactions.
- the anodes are made of carbon and are consumed during the electrolytic reaction. The anodes need to be replaced after 3 to 4 weeks. Consumption of the carbonaceous material releases large quantities of carbon dioxide in the atmosphere.
- a purifier assembly for removing impurities from an electrolytic bath before using the same in an electrolytic cell for the making of a metal
- the purifier assembly comprising: a purification tank located upstream an electrolytic cell and configured to contain at least a portion of the electrolytic bath; and at least one row of alternating vertically oriented cathodes and anodes configured to be operatively connected to a power supply for providing an electric current to the anodes and cathodes, wherein the at least one row of vertically oriented cathodes and anodes is configured in size to be inserted into the purification tank; and wherein the purifier assembly is configured to provide and maintain an anode-to-cathode distance (ACD) between each of said vertically oriented cathodes or anodes.
- ACD anode-to-cathode distance
- the purifier assembly further comprises at least two parallel rows of alternating vertically oriented cathodes and anodes, each anode or cathode of one row being adjacent respectively to another anode or cathode of adjacent parallel rows, forming as such an array of alternating columns of vertically oriented cathodes and anodes.
- the purifier assembly further comprising: at least one anode connection rail configured to be operatively connected to the power supply, each of the anode connection rail being configured to support one row of vertically oriented anodes and to electrically connect the anodes one to each other in a parallel arrangement; and at least one a cathode connection rail configured to be operatively connected to the power supply, each cathode connection rail being configured to support one row of vertically oriented cathodes and to electrically connect the cathodes one to each other in a parallel arrangement.
- the at least one anode and cathode connection rails are configured to be independently moved at a desired position relative to the electrolytic bath in the purification tank. More preferably, the at least one cathode connection rail is configured to entirely plunge the cathodes below a bath-vapor interface of the electrolytic bath.
- each of the anodes or cathodes comprises a longitudinal stem having one end connected to an anode body or a cathode plate, and an opposite end configured to be operatively connected to the anode or cathode connection rails respectively.
- each of the anode bodies and cathode plates have a top extremity connected to their respective stems, the top extremities of the cathodes being located below the top extremities of the anodes when the row of electrodes is plunged into the electrolytic bath in order to have the cathode plates entirely plunged into the bath.
- the anode body comprises carbon or graphite
- the cathode plates comprises steel or stainless steel
- the longitudinal stem comprises steel or stainless steel.
- each of the anodes and cathodes further comprises a protective sleeve around the longitudinal stem for protecting the longitudinal stem from corrosion.
- the longitudinal sleeve comprises: a metal oxide of the metal to be produced, the metal oxide being aluminum oxide when the metal to be produced is aluminum; a semi-noble metal, such as copper; or silicon carbide (SiC).
- the purifier assembly further comprises a supporting structure for securing the at least one row of alternating vertically oriented cathodes and anodes at a position relative to the purification tank.
- the connection rails are secured to the supporting structure for reinforcing and stabilizing the position of anodes and cathodes.
- the supporting structure is configured in size to close a top opening of the purification tank and seal the tank.
- the supporting structure is configured to provide insulation, to be resistant to corrosion and to prevent gas from escaping the purification tank when the top opening is closed, the purification tank being then equipped with a gas outlet for safely collecting anode gas.
- the purification tank may belongs to a melter, the melter being used for melting a dry (solid) bath of said electrolytic bath.
- the at least one row of alternating vertically oriented cathodes and anodes forms a compact array with an ACD ranging from about 1 cm to about 5 cm, preferably about 2.5 cm.
- the power supply comprises a DC rectifier.
- the metal to produce by the electrolytic cell is aluminum, the electrolytic bath then comprising cryolite and additives, and the impurities to remove comprising sulfur, phosphorus, iron, nickel, chromium, copper, gallium or mixture thereof.
- a method for removing impurities from an electrolytic bath before using the same in an electrolytic cell for the making of a metal comprising the steps of: injecting at least a portion the electrolytic bath to purify into a purification tank located upstream an electrolytic cell; positioning into the purification tank at least one row of alternating vertically oriented cathodes and anodes configured to be operatively connected to a power supply for providing an electric current to the anodes and cathodes, the at least one row of alternating vertically oriented cathodes and anodes being configured in size to be inserted into the purification tank and to provide and maintain an anode-to-cathode distance (ACD) between each of the vertically oriented cathodes or anodes; and applying the electric current between the anodes and cathodes for a period of time to remove impurities from the electrolytic bath.
- ACD anode-to-cathode distance
- each of the cathodes comprises a cathode plate, the cathodes being positioned in the electrolytic bath so as to be entirely submerged in the electrolytic bath.
- the method further comprises the step of: melting the dry bath before injecting at least the portion the electrolytic bath into the purification tank; or melting the dry bath directly in the purification tank.
- the electric current is a direct current applied using a DC rectifier.
- applying the electric current comprises measuring an amount of impurities present in the bath before adapting a total electric charge passing through a purifier assembly comprising said purification tank and said at least one row of alternating vertically oriented cathodes and anodes.
- the total charge is about 0.1 to about 10 Ampere-hours (Ah) per kilogram of electrolytic bath to purify, more preferably about 0.3 to about 4.0 Ampere-hours (Ah) per kilogram of electrolytic bath to purify.
- a current density of the cathodes is about 0.004 to about 0.4 A/cm 2 , preferably about 0.1 to about 0.3 A/cm 2 .
- the voltage across a purifier assembly comprising the row of alternating vertically oriented cathodes and anodes and the purification tank is between about 0.5 V and about 2.5 V.
- the period of time is between about 1 to about 150 hours, preferably between about 24 to about 96 hours.
- the method further comprises increasing current density for either increasing a specific electrical charge (Ah/kg bath), reducing the period of time of purification, or a combination thereof.
- the method further comprises removing the cathodes from the purification tank and removing solid impurities accumulated on the cathodes.
- the metal to produce by the electrolytic cell is aluminum, the bath then comprising cryolite and additives, the impurities to remove comprising sulfur, phosphorus, iron, nickel, chromium, copper, gallium or mixture thereof.
- the additives comprises sodium fluoride, aluminum fluoride, calcium fluoride, and/or aluminum oxide.
- a purifier assembly for purifying an electrolytic bath located in a purification tank located upstream an electrolytic cell, the bath once purified being used in said electrolytic cell for the making of a metal.
- the purifier assembly comprises alternating anodes and cathodes in a compact array, the compact array being configured in size to be inserted into the purification tank; and the purifier assembly being configured to be operatively connected to a power supply located outside the purification tank for providing an electric current to the anodes and cathodes.
- a method for purifying an electrolytic bath of an electrolytic cell comprising the steps of: a) charging the electrolytic bath into a purification tank; b) inserting the anodes and cathodes of the purifier assembly as disclosed herein into the tank until the anodes and cathodes are plunged, at least partially, into the electrolytic bath; and c) applying a current between the anodes and cathodes for a given period of time to remove impurities from the bath.
- the invention is particularly adapted for the purification of electrolytic bath of electrolytic cell using inert or oxygen-evolving anodes requiring a bath of higher purity.
- Purifying electrolytic bath by immersing and passing DC current through a graphite or carbon anode to a steel or metallic cathode for a period of time, has been found adequate to deposit as solid metals and compounds, various impurities, such as Fe, Ni, Cr, Cu, S and P on the cathodes, as well as liberate additional impurities, such as sulfur dioxide gas from the anode.
- Figure 1 is a schematic illustration of a purifier assembly according to a preferred embodiment
- Figure 2 is a schematic illustration of a purifier assembly located upstream the electrolytic cell according to a preferred embodiment
- Figure 3 is a three-dimensional illustration of an anode according to a preferred embodiment
- Figure 4 is a three-dimensional illustration of a cathode according to a preferred embodiment
- Figure 5 is a three-dimensional illustration of electrodes of a purifier assembly according to a preferred embodiment
- Figure 6A is a top isometric illustration of a purifier assembly according to another preferred embodiment
- Figure 6B is a bottom isometric illustration of the electrodes of the purifier assembly illustrated on Figure 6A;
- Figure 6C is a top isometric illustration the electrodes and guardrails illustrated on Figures 6A and 6B;
- Figure 6D is a bottom isometric illustration the electrodes and guardrails illustrated on Figure 6C;
- Figure 7A is an isometric illustration the electrodes and guardrails of a purifier assembly according to another preferred embodiment
- Figure 7B is a front plan view of the electrodes and guardrails of the purifier assembly illustrated on Figure 7A;
- Figure 7C is a closer view of the guardrails illustrated on Figure 7A and 7B;
- Figure 7D is a closer view of the electrodes 7 illustrated on Figure 7A and 7B;
- Figure 8 is a flowchart illustrating the method for removing impurities from an electrolyte assembly according to another preferred embodiment
- Figure 9 is a top isometric illustration of two rows of electrodes according to another preferred embodiment.
- Figure 10 is a cross-sectional view of a purifier assembly with the two rows of electrodes illustrated on Figure 9 inserted into a purification tank according to another preferred embodiment.
- % or wt.% means weight % unless otherwise indicated. When used herein % refers to weight % as compared to the total weight percent of the phase or composition that is being discussed.
- the invention as disclosed herein is directed to an apparatus, also named purifier assembly, for removing impurities from an electrolytic bath or electrolyte of an electrolytic cell.
- the electrolytic cell is preferably used for the making of metals, such as aluminum.
- the electrolyte then comprises cryolite and the impurities to remove comprise sulfur, phosphorus, iron, gallium or mixture thereof
- FIGs 1 and 2 are schematic illustrations of a purifying system in accordance with the principle of the invention.
- the purifier assembly 100 allows purifying or removing impurities from an electrolytic bath 102 located in a purification tank 104 located upstream an electrolytic cell 200 ( Figure 2).
- An inlet 101 can be provided to introduce the electrolyte in the tank 104.
- the bath 102 once purified is transferred to the electrolytic cell 200 for the making of a metal.
- the bath 102 once purified can be transferred 109 to the cell 200 by siphoning it into a crucible before pouring it into the cell. Other way for transferring the electrolyte once purified from the purifier assembly to the electrolytic cell can be considered.
- the bath forms a bath-vapor interface 103.
- the electrolytic bath typically comprises cryolite and additives.
- the additives comprises sodium fluoride, aluminum fluoride, calcium fluoride, and/or aluminum oxide.
- the purifier assembly 100 may comprise one or more rows of alternating vertically oriented anodes 112 and cathodes 114, preferably forming a compact array of one row (see e.g. Figures 6 and 7), two rows (see e.g. Figure 5), or more rows of alternating anodes and cathodes.
- the electrodes are configured in size to be inserted or plunged into a purification tank 104.
- the purifier assembly 100 can then be operatively connected to a power supply 120, preferably located outside the purification tank 104 and operatively connected the anodes and cathodes for providing an electric current to the anodes and cathodes.
- the purifier assembly as disclosed herein comprises anodes and cathodes, preferably in a compact array.
- the anode’s body of the anodes can comprises carbon, preferably graphite.
- the cathodes are typically cathode plates of steel or stainless steel. All the anodes are electrically connected to each other in a parallel arrangement. Likewise, the cathodes are preferably connected to each other in a parallel arrangement.
- the purifier assembly as disclosed herein is configured to be operatively connected to the power supply, preferably comprising a DC rectifier providing a direct current.
- each anode 112 of one row 113 may be connected to an anode connection rail or guardrails 116 whereas each cathode 114 of the same row is connected to a cathode connection rail or guardrails 118.
- the anode and cathode connection rail 116, 118 are operatively connected to the power supply 120, preferably a DC rectifier, for generating a direct current that will pass through the anodes 112 and cathodes 114 submerged in the purification tank 110.
- the cathodes are fully submerged into the bath to avoid or limit corrosion thereof.
- the purifier assembly 100 comprises two rows 113, 115 of multiple parallel alternating anodes 112 and cathodes 114 in a compact array.
- compact array refers to an anode-to-cathode distance (ACD) of up to about 5 cm, preferably between 1 cm and 3 cm, and even more preferably about 2.5 cm.
- ACD anode-to-cathode distance
- the anode-cathode distance is nominally about 2.5 cm, but can be varied.
- the anode connection rail 116 is configured to support and electrically connect the anodes 112 to each other in a parallel arrangement.
- the anode and cathode connection rails are preferably configured to be independently moved at a desired position relative to the electrolytic bath in the purification tank.
- each of the anode bodies 121 and cathode plates 141 have a top extremity 121a, 141a connected to their respective stems 122, 142.
- the top extremities of the cathodes 121a is positioned below the top extremities of the anodes 141a when the row of electrodes is plunged into the electrolytic bath in order to have the cathode plates entirely plunged into the bath or below the bath-vapor interface. This advantageously protect the cathodes plates, preferably made of steel as detailed herein below, from corrosion of the vapors above the interface.
- each anode 112 comprises an anode body 121 and a longitudinal stem 122 for electrically connecting each anode body to the anode connection rail 116.
- the longitudinal stem 122 may be made of any suitable conductive material, and may be threaded for securely and electrically connecting the longitudinal stem 122 to the connection rail 116 using, for example, stainless steal fasteners.
- the anode body 121 may comprises carbon or graphite.
- an anode connection rail 116 may comprise a plurality of openings 117, configured to receive and maintain the stem of the anodes.
- the openings 117 are located along the rail 116 about 2 cm to 10 cm from another opening so as to maintain an anode-to-cathode distance (ACD), for instance of about 1 cm to 5 cm when the anode connection rail 116 and the cathode connection rail 118 are “sandwiched” together in the purifying assembly.
- ACD anode-to-cathode distance
- the rails can be each a one peace element with lateral extensions 116b, 118b allowing the openings 117, 119 of the rails 116, 118 to intermingle in a way that all the openings of both rails are aligned to form the electrode row 113.
- FIG 6C Another embodiment of the rails is illustrated on Figure 6C for instance, where each rail comprises a main longitudinal element 116a with extension 116b hingely fixed thereto, the opening 117 being located at the end of the extension 116b.
- the center-to-center distance between two anode openings may be twice the ACD plus the thickness of one anode body 121 and one cathode plate 141. It may be the same for the cathode rails as discussed herein after.
- the distance between the surfaces or faces of two anodes is typically twice the ACD plus the thickness of the cathode plate 141 located between two anode bodies 121.
- the anode 112 may further comprise a sleeve 123 for encapsulating and protecting the longitudinal stem 122 from the electrolytic bath and vapors, preferably adjacent the anode plate.
- the sleeve is preferably cylindrical and may be removably secured onto a supporting structure, or separator plate, using fasteners or the like.
- the sleeve is preferably made of a metal oxide of the metal to be produced.
- an anode for the production of aluminum will comprise a sleeve made of a metal oxide that comprises aluminum oxide, or alumina, or also silicon containing material, such as silicon carbide. Another option would be to use copper for the sleeve.
- the anodes are sacrificial anodes, preferably comprising carbon or graphite.
- the anode can be connected to the stem 122 using, for instance, a threaded connection 124 as visible on Figure 6D for instance where one anode is transparently illustrated to show the connection in the anode body.
- the purifier assembly also comprises a cathode connection rail 118 configured similarly as the anode connection rail 116, for supporting and electrically connecting the cathodes to each other in a parallel arrangement along the row
- each cathode 114 preferably comprises a cathode plate 141 and a longitudinal stem 142 for electrically connecting each cathode plate to the cathode connection rail 118.
- the longitudinal stem 142 may be made of any suitable conductive material, preferably steel, and may be threaded for securely and electrically connecting the longitudinal stem to the connection rail using, for example, stainless steal fasteners.
- the cathode connection rail 118 comprises a plurality of openings 119, each about 2 cm to 10 cm from another opening so as to maintain an anode- to-cathode distance (ACD) of about 1 cm to 5 cm when the anode connection rail 116 and the cathode connection rail 118 are “sandwiched” together in the purifying assembly.
- ACD anode- to-cathode distance
- the center-to-center distance between two cathodes openings of the cathode rail may be twice the ACD plus the thickness of one anode body 121 and one cathode plate 141.
- the distance between two cathode plate surfaces may be twice the ACD plus the thickness of one anode.
- the cathode 114 may further comprise a sleeve 143 for encapsulating and protecting the longitudinal stem 142 from the electrolytic bath in a region of the longitudinal stem adjacent the cathode plate.
- the sleeve 143 is preferably cylindrical and may be removably secured onto a supporting structure, or separator plate, using fasteners or the like.
- the sleeve is preferably made of a metal oxide of the metal to be produced in downstream applications.
- a cathode for the production of aluminium will comprise a sleeve made of metal oxide that comprises aluminum oxide, or alumina.
- a semi-noble metal, such as copper, and also silicon containing material, such as silicon carbide, have also been found to work well as a sleeve material.
- the cathode plate 141 comprises steel, preferably stainless steel.
- the plate 141 and the stem 142 are made of the same metal or alloy, such as steel, the two can be connected together using continuous welding 144, as visible on Figure 4.
- Other material for the cathode can used as long as the material is conductive to electricity and resistant to corrosion in contact with the electrolytic bath and gas.
- Non-limiting examples are steel, nickel, copper, or carbon.
- the electrodes of the purifier assembly 100 may be mounted onto a supporting structure 150 for securing the electrodes 112, 114 at a desired position relative to the purification tank 104.
- the supporting structure may comprises a bridge 152, such as the one illustrated on Figures 6A, 6B or 7A, 7B, for moving and supporting the electrodes over the tank 104.
- the array of electrodes 112, 114 may be mounted onto the supporting structure using fasteners and the threaded longitudinal stem. The anodes and cathodes are therefore secured to both the guardrail 116, 118 and the supporting structure 150.
- the guardrails 116, 118 may also be secured onto the supporting structure 150 to reinforce and stabilize the position of the electrodes 112, 114.
- the purifier assembly is configured for varying the anode-cathode distance (ACD).
- the supporting element 150 may comprises elongated slots 154 to allow lateral movements of the stems.
- the central electrode 114c preferably a cathode, can be fixed as a reference point, whereas the other cathodes and anodes can be laterally movable to adjust the ACD.
- the supporting structure 150 of the purifier assembly 100 may also be configured in size to close a top opening 105 of the tank 104 of the purifier 100.
- the supporting structure 150 may also provide insulation, be resistant to corrosion and prevent gas from escaping the tank.
- the tank 104 can be equipped with a gas outlet 107 for safely collecting the anode gas.
- the supporting structure 150 of the purifier assembly may also comprises several attachment elements 156 for attaching the supporting structure and electrodes and moving them in and out the tank 104.
- a method for removing impurities from an electrolytic bath or electrolyte of an electrolytic cell is also disclosed.
- a raw non-purified bath 102 of electrolyte is transferred into the purification tank 104, for instance via the inlet 101.
- the electrodes 112, 114 are plunged in the raw bath 102.
- the cathode plates of the cathodes 114 of the purifier assembly 100 are entirely submerged in the bath 102, limiting as such the corrosion of the top end of the cathode plates that would be above the bath-vapor interface 103 during purification.
- the power supply 120 such as the direct current (DC) rectifier, is then activated to supply direct current to the anodes and cathodes submerged in the raw bath.
- DC direct current
- the electrical current is then applied for a period of time until the impurities deposit onto the cathode surface or are released with the anode gas (e.g. sulfur dioxide, hydrogen sulfide, carbonyl sulfide, etc.).
- the purified bath 102 may be then transferred 109 into the electrolysis cell 200 for downstream applications, for example, aluminum production.
- the method 1000 for removing impurities from an electrolytic bath before using the same in an electrolytic cell for the making of a metal comprise the steps of: injecting 1010 at least a portion the electrolytic bath to purify into a purification tank located upstream an electrolytic cell; positioning 1020 into the purification tank at least one row of alternating vertically oriented cathodes and anodes configured to be operatively connected to a power supply for providing an electric current to the anodes and cathodes, the at least one row of alternating vertically oriented cathodes and anodes being configured in size to be inserted into the purification tank and to provide and maintain an anode-to-cathode distance (ACD) between each of the vertically oriented cathodes or anodes; and applying the electric current 1030 between the anodes and cathodes for a period of time to remove impurities from the electrolytic bath.
- ACD anode-to-cathode distance
- the method 1000 may further comprise the step of: melting the dry bath 1040 before injecting at least the portion the electrolytic bath into the purification tank; or melting the dry bath 1050 directly in the purification tank.
- a dry electrolytic bath e.g. solid cryolite
- the method comprises, before the step of charging a dry bath, the step of mounting the purifier assembly onto a first supporting structure for securing the assembly at a desired position.
- the impurities to be removed may comprise, but are not limited to, sulfur, phosphorus, iron, nickel, chromium, copper, and/or gallium.
- the impurities accumulated on the surfaces of the cathodes are periodically removed therefrom, for instance by scraping.
- the gas impurities are safely recovered from the tank via the gas outlet 107.
- the amount of current to be applied will depend on several parameters such as the number of electrodes of the purifier assembly, typically selected in function of the size of the purification tank and the amount of electrolyte to purify.
- a constant direct current is applied with a total charge of preferably about 0.1 to 10, preferably from about 0.3 to 4.0, Ampere-hours per kilogram of bath to purify.
- the current density is between about 0.004 to about 0.3 A/cm 2 , preferably from 0.1 to about 0.3 A/cm 2
- the voltage across the purifying assembly may be between about 0.5 V and about 2.5 V.
- the period of time for removing the impurities may be 1 hour to about 150 hours, more preferably between about 24 to about 96 hours.
- applying the electric current may comprises measuring an amount of impurities present in the bath before adapting a total charge of current passing between the cathodes and anodes.
- the method 1000 comprises removing the cathodes after purification 1060 to clean and remove solid impurities therefrom.
- the method further comprises adding the purified bath to the electrolytic cell prior to start electrolysis.
- the present invention provides a method of achieving the desired amperage and electrode surface area in a much smaller cross-section. This makes it possible to install the electrodes of the purifier through an insulated lid of a commercial-sized bath melter within a reasonably-sized work port.
- the experimental purifying unit described below has produced the basic metric for the design base for the pilot unit.
- the guiding metric used is Ampere Hours/Kilogram Bath.
- the experimental unit comprised one flat, steel plate cathode and one cylindrical graphite anode. Since there were only one anode and one cathode, the cathode and anode current densities were calculated based only on the area of the side facing the opposite electrode (i.e. 50% the total submerged surface area).
- a prototype bath purifier was constructed, comprising an array of 4 anodes and 3 cathodes, each electrode being rectangular in shape 19 cm tall and 6.35 cm wide, with a 2.54 cm ACD.
- the anodes comprised a fine-grained graphite, 40 mm thick and the cathodes comprised carbon steel, 10 mm thick.
- the purifier was immersed in a molten bath containing impurities to a level of about 2.5 cm below the electrode to rod connection.
- the molten bath is preferably a molten salt composed of sodium fluoride, aluminum fluoride and calcium fluoride and is typically the same that is used in the electrolytic cell.
- a DC rectifier used to power the purifier was set for 7 A constant current and run for 72 hrs.
- the rectifier voltage initially started at 1.15 V and reduced to about 0.7 V after 12 hours.
- Bath samples were taken at 12 hour intervals and analyzed for impurities. The results are given below in Table 3 in parts per million (ppm).
- Table 3 Concentration of impurities in the bath at 12 hour intervals for 72 hours of purification
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Electrolytic Production Of Metals (AREA)
- Water Treatment By Electricity Or Magnetism (AREA)
- Secondary Cells (AREA)
Abstract
Description
Claims
Priority Applications (7)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CA3197049A CA3197049A1 (en) | 2020-11-24 | 2021-11-23 | Removing impurities from an electrolyte |
CN202180079016.4A CN116583629A (en) | 2020-11-24 | 2021-11-23 | Impurity removal in electrolytes |
US18/038,358 US20240003030A1 (en) | 2020-11-24 | 2021-11-23 | Removing impurities from an electrolyte |
EP21895995.5A EP4251791A1 (en) | 2020-11-24 | 2021-11-23 | Removing impurities from an electrolyte |
AU2021386476A AU2021386476A1 (en) | 2020-11-24 | 2021-11-23 | Removing impurities from an electrolyte |
ZA2023/05470A ZA202305470B (en) | 2020-11-24 | 2023-05-19 | Removing impurities from an electrolyte |
DKPA202370307A DK202370307A1 (en) | 2020-11-24 | 2023-06-19 | Removing impurities from an electrolyte |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US202063117483P | 2020-11-24 | 2020-11-24 | |
US63/117,483 | 2020-11-24 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2022109725A1 true WO2022109725A1 (en) | 2022-06-02 |
Family
ID=81753963
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/CA2021/051665 WO2022109725A1 (en) | 2020-11-24 | 2021-11-23 | Removing impurities from an electrolyte |
Country Status (8)
Country | Link |
---|---|
US (1) | US20240003030A1 (en) |
EP (1) | EP4251791A1 (en) |
CN (1) | CN116583629A (en) |
AU (1) | AU2021386476A1 (en) |
CA (1) | CA3197049A1 (en) |
DK (1) | DK202370307A1 (en) |
WO (1) | WO2022109725A1 (en) |
ZA (1) | ZA202305470B (en) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0028158A1 (en) * | 1979-10-29 | 1981-05-06 | Diamond Shamrock Corporation | Methods and systems of removal of metals from solution and of purification of metals and purified solutions and metals so obtained |
EP0613398B1 (en) * | 1991-11-13 | 1997-06-04 | Firma Rudolf Jatzke | Process, medium and device for electrodialytically regenerating the electrolyte of a galvanic bath or the like |
US7846309B2 (en) * | 2003-08-14 | 2010-12-07 | Rio Tinto Alcan International Limited | Metal electrowinning cell with electrolyte purifier |
-
2021
- 2021-11-23 US US18/038,358 patent/US20240003030A1/en active Pending
- 2021-11-23 EP EP21895995.5A patent/EP4251791A1/en active Pending
- 2021-11-23 WO PCT/CA2021/051665 patent/WO2022109725A1/en active Application Filing
- 2021-11-23 CN CN202180079016.4A patent/CN116583629A/en active Pending
- 2021-11-23 CA CA3197049A patent/CA3197049A1/en active Pending
- 2021-11-23 AU AU2021386476A patent/AU2021386476A1/en active Pending
-
2023
- 2023-05-19 ZA ZA2023/05470A patent/ZA202305470B/en unknown
- 2023-06-19 DK DKPA202370307A patent/DK202370307A1/en unknown
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0028158A1 (en) * | 1979-10-29 | 1981-05-06 | Diamond Shamrock Corporation | Methods and systems of removal of metals from solution and of purification of metals and purified solutions and metals so obtained |
EP0613398B1 (en) * | 1991-11-13 | 1997-06-04 | Firma Rudolf Jatzke | Process, medium and device for electrodialytically regenerating the electrolyte of a galvanic bath or the like |
US7846309B2 (en) * | 2003-08-14 | 2010-12-07 | Rio Tinto Alcan International Limited | Metal electrowinning cell with electrolyte purifier |
Also Published As
Publication number | Publication date |
---|---|
AU2021386476A1 (en) | 2023-06-22 |
CA3197049A1 (en) | 2022-06-02 |
US20240003030A1 (en) | 2024-01-04 |
EP4251791A1 (en) | 2023-10-04 |
ZA202305470B (en) | 2024-01-31 |
CN116583629A (en) | 2023-08-11 |
DK202370307A1 (en) | 2023-07-06 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US11001931B2 (en) | Systems and methods for purifying aluminum | |
EP0638133B1 (en) | Anode-cathode arrangement for aluminum production cells | |
US7077945B2 (en) | Cu—Ni—Fe anode for use in aluminum producing electrolytic cell | |
DK181300B1 (en) | Electrolytic cells for producing aluminium metal | |
US6558525B1 (en) | Anode for use in aluminum producing electrolytic cell | |
US20070278107A1 (en) | Anode for use in aluminum producing electrolytic cell | |
CA2860813A1 (en) | System for power control in cells for electrolytic recovery of a metal | |
US6811676B2 (en) | Electrolytic cell for production of aluminum from alumina | |
EP1654401B1 (en) | Metal electrowinning cell with electrolyte purifier | |
US20240003030A1 (en) | Removing impurities from an electrolyte | |
US6800191B2 (en) | Electrolytic cell for producing aluminum employing planar anodes | |
EA045537B1 (en) | REMOVAL OF CONTAMINANTS FROM THE ELECTROLYTIC BATH | |
Thonstad | Some recent trends in molten salt electrolysis of titanium, magnesium, and aluminium |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 21895995 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 3197049 Country of ref document: CA |
|
WWE | Wipo information: entry into national phase |
Ref document number: 18038358 Country of ref document: US |
|
WWE | Wipo information: entry into national phase |
Ref document number: 202180079016.4 Country of ref document: CN |
|
REG | Reference to national code |
Ref country code: BR Ref legal event code: B01A Ref document number: 112023009614 Country of ref document: BR |
|
WWE | Wipo information: entry into national phase |
Ref document number: PA202370307 Country of ref document: DK |
|
ENP | Entry into the national phase |
Ref document number: 2021386476 Country of ref document: AU Date of ref document: 20211123 Kind code of ref document: A |
|
ENP | Entry into the national phase |
Ref document number: 112023009614 Country of ref document: BR Kind code of ref document: A2 Effective date: 20230518 |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
ENP | Entry into the national phase |
Ref document number: 2021895995 Country of ref document: EP Effective date: 20230626 |
|
WWE | Wipo information: entry into national phase |
Ref document number: 523440885 Country of ref document: SA |