CA2860814A1 - Method of operating an electrolysis cell and cathode frame - Google Patents
Method of operating an electrolysis cell and cathode frame Download PDFInfo
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- CA2860814A1 CA2860814A1 CA2860814A CA2860814A CA2860814A1 CA 2860814 A1 CA2860814 A1 CA 2860814A1 CA 2860814 A CA2860814 A CA 2860814A CA 2860814 A CA2860814 A CA 2860814A CA 2860814 A1 CA2860814 A1 CA 2860814A1
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- side member
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- 238000005868 electrolysis reaction Methods 0.000 title claims abstract description 21
- 238000000034 method Methods 0.000 title abstract description 21
- 239000003792 electrolyte Substances 0.000 claims abstract description 54
- 238000005363 electrowinning Methods 0.000 claims abstract description 23
- 229910052751 metal Inorganic materials 0.000 claims abstract description 15
- 239000002184 metal Substances 0.000 claims abstract description 15
- 238000011010 flushing procedure Methods 0.000 claims abstract description 3
- 238000012384 transportation and delivery Methods 0.000 claims description 36
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 25
- 239000000463 material Substances 0.000 claims description 11
- 229910052759 nickel Inorganic materials 0.000 claims description 11
- 229910052748 manganese Inorganic materials 0.000 claims description 6
- 239000011572 manganese Substances 0.000 claims description 6
- 239000010949 copper Substances 0.000 claims description 5
- 208000034423 Delivery Diseases 0.000 claims description 4
- 229910052802 copper Inorganic materials 0.000 claims description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 3
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 3
- 230000015556 catabolic process Effects 0.000 claims description 3
- 239000010931 gold Substances 0.000 claims description 3
- 150000002739 metals Chemical class 0.000 claims description 3
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 2
- 229910052737 gold Inorganic materials 0.000 claims description 2
- 229910052709 silver Inorganic materials 0.000 claims description 2
- 239000004332 silver Substances 0.000 claims description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims 1
- -1 co-balt Co Substances 0.000 claims 1
- 238000000429 assembly Methods 0.000 abstract description 10
- 230000000712 assembly Effects 0.000 abstract description 10
- 239000007789 gas Substances 0.000 description 66
- 210000000188 diaphragm Anatomy 0.000 description 30
- 239000001257 hydrogen Substances 0.000 description 6
- 229910052739 hydrogen Inorganic materials 0.000 description 6
- 230000007772 nodular growth Effects 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 150000002431 hydrogen Chemical class 0.000 description 4
- 239000002253 acid Substances 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 239000004744 fabric Substances 0.000 description 2
- 239000003292 glue Substances 0.000 description 2
- 230000002706 hydrostatic effect Effects 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000012466 permeate Substances 0.000 description 2
- 239000002861 polymer material Substances 0.000 description 2
- 238000002791 soaking Methods 0.000 description 2
- 239000007858 starting material Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010349 cathodic reaction Methods 0.000 description 1
- 238000003889 chemical engineering Methods 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 229940043264 dodecyl sulfate Drugs 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 239000004922 lacquer Substances 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- YELGFTGWJGBAQU-UHFFFAOYSA-N mephedrone Chemical compound CNC(C)C(=O)C1=CC=C(C)C=C1 YELGFTGWJGBAQU-UHFFFAOYSA-N 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920000136 polysorbate Polymers 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 229910021653 sulphate ion Inorganic materials 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
- C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
- C25C1/06—Electrolytic production, recovery or refining of metals by electrolysis of solutions or iron group metals, refractory metals or manganese
- C25C1/08—Electrolytic production, recovery or refining of metals by electrolysis of solutions or iron group metals, refractory metals or manganese of nickel or cobalt
-
- 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
- C25B13/00—Diaphragms; Spacing elements
-
- 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
-
- 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
-
- 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
- C25C7/04—Diaphragms; Spacing elements
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electrolytic Production Of Metals (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
Abstract
The invention relates to a method of operating an electrolysis cell in electrowinning of metal, wherein cathode plates (1) are arranged in cathode frames (2) and the cathode plate and cathode frame are enclosed in a diaphragm bag (3) so as to form a cathode bag as- sembly, and the cathode bag assemblies and anode plates (4) are arranged in the electrolyte in an electrolysis cell (5) in an alternating and consecutive manner. A gas-sparging means (6) is disposed in each of the cathode bag assemblies, and sparging gas is supplied to the gas-sparging means (6) such that the gassparging means forms a curtain of fine sparging gas bubbles to flush the cathode plate (1). The cathode frame (2) comprises a gas-sparging means (6) for flushing the cathode plate (1) with a curtain of fine sparging gas bubbles inside the cathodic compartment.
Description
METHOD OF OPERATING AN ELECTROLYSIS CELL AND CATHODE
FRAME
FIELD OF THE INVENTION
The present invention relates to a method of operating an electrolysis cell in electrowinning of metal, wherein cathode plates are arranged in cathode frames.
The cathode plate and the cathode frame are enclosed in a diaphragm bag so as to form a cathode bag assem-bly. The cathode bag assemblies and anode plates are arranged in the electrolyte in an electrolysis cell in an alternating and consecutive manner. Further, the invention relates to a cathode frame configured to re-tain a cathode plate and a diaphragm bag which enclos-es said cathode plate inside said cathode frame to form a cathodic compartment inside the diaphragm bag.
BACKGROUND OF THE INVENTION
Electrowinning is a process where a metal dissolved in an electrolyte is reduced on a cathode by means of electric current. Electrowinning takes place in an electrolytic cell that contains a number of anodes and a number of cathodes arranged in an alternating man-ner.
When an electric current is conducted to the electrol-ysis system, metal is precipitated on the surface of the cathode and oxygen is generated on the anodes when the water decomposes, acid and oxygen are formed on the anodes, according to the reaction equations (1) and (2):
Anodic reaction: H20 , 2H+ + 1402 + 2e- (1) (1) Cathodic reaction: Mez+ + ze- ' Me (2) Me = metal, such as Ni, Co, Mn or Cu wherein z = the charge of a metal ion A diaphragm technique can be used in electrowinning metals, which in the electrochemical series are less noble than hydrogen, eg. Ni, Co, Mn. The overpotential of the reduction of these metals is higher than that of hydrogen, which is why the development of hydrogen at a low pH should be avoided by separating the anolyte and the catholyte from each other by a material that perme-ates the electrolyte in a controlled manner, such as a diaphragm fabric, and the electrolyte should flow from the catholyte compartment to the anolyte compartment.
Typically, in sulphate-based nickel, manganese and co-balt electrowinning, said metal can be recovered using divided-cell electrowinning technology, i.e. where the anode and cathode compartments in the cell are sepa-rated appropriately. In such tankhouses, the solution surrounding the cathode (catholyte) is separated from the adjacent anodes in the cell by slotting each cath-ode into a suitable frame, over which a bag of dia-phragm material is stretched. The diaphragm material of the bag permeates the electrolyte in a controlled manner.
A typical target in nickel electrowinning is to have a high delta-Ni (also known as bite i.e. difference in Ni concentrations between the electrolyte fed to the electrolysis cell and electrolyte overflown from the cell), or a high anolyte sulfuric acid concentration.
The higher the delta-Ni, the more economic is the pro-cess since no excess circulation in the leaching SX-EW-circuit exists. When said cathode bag technology (cathodes are in bags in order to keep catholyte pH
high enough for the Ni-EW process) is used, delta-Ni can be increased by two ways, by 1) increasing the current density 2) decreasing the electrolyte flow rate to the cathode bag and consequently through the diaphragm used to separate anodic and cathodic compartment from each other.
In nickel electrowinning, increasing current density is limited at the typical industrial conditions and not much higher than 200 A/m2 can be used without se-rious problems in cathode quality. Increasing current density causes increased nodular growth of metal at the lower end of the cathode. Heavy nodular growth may tear the bag. A torn bag allows acid to migrate into the catholyte compartment thus suppressing the pH to a level at which hydrogen is produced. This causes pit-ting on the cathode surface resulting in a rough sur-face. Hydrogen formation causes also a risk of explo-sion. Nodular growth of the cathode tearing the bag may also cause a shortcut to the neighboring anode thereby decreasing the current efficiency.
Another possibility is to decrease the electrolyte flow through the diaphragm bags. However, when cathode bags are used this option is not possible since it is difficult to distribute even flow over the tankhouse and in addition, the electrolyte retention time inside the diaphragm bag would be very long and electrolyte flow/circulation (inside the bag) would be too slow.
Also temperature control is difficult with slow elec-trolyte flow.
In prior art, as is known from documents WO
2005/019502 Al, US 3,959,112, US 6,849,172 B2 and ar-ticle "Gas bubble induced mixing in electrowinning baths" G. D. Rigby; P. E. Grazier, A. D. Stuart, E. P.
Smithson; Chemical Engineering Science 56 (2001) 6329-6336, gas-sparging has been utilized in copper elec-trowinning to obtain higher current density and to produce high quality metal cathode. It is known that the gas bubbles arising along the electrode surface decrease the Nernst diffusion layer and thereby in-crease the limiting current density (and the critical current density). Thereby a higher current density is possible to be used without decreasing the surface quality of the deposit on the electrode. Typically, in prior art, a gas-sparging manifold has been arranged at the bottom of the electrolysis cell. However, this kind of arrangement of the gas-sparging manifold at the bottom of the cell is not usable in the cathode bag technology since the diaphragm prevents the bub-bles from reaching the cathode.
Therefore, an object of the present invention is to alleviate the problems described above and to intro-duce a method of operating an electrolysis cell and a cathode frame that allow the electrowinning to be op-erated at a high current density and at the same time to achieve a high quality cathode deposit with a smooth surface and with a minimum amount of nodular growth.
Further, the object of the invention is to introduce a method of operating an electrolysis cell and a cathode frame that allow to achieve a high delta-Me (differ-ence in the metal concentrations between the electro-lyte fed to the cell and electrolyte overflown from the cell) whereby less cells are needed to obtain the same capacity.
Further, the object of the invention is to introduce a method of operating an electrolysis cell and a cathode frame that minimize the number of torn cathode bags and short-cuts and therefore to achieve a high current efficiency.
Further, the object of the invention is to introduce a method of operating an electrolysis cell and a cathode frame that allow a good mixing of the electrolyte re-sulting in a homogenous electrolyte inside the cathode 5 bag.
SUMMARY OF THE INVENTION
A first aspect of the present invention is a method of operating an electrolysis cell in electrowinning of metal, wherein cathode plates are arranged in cathode frames and the cathode plate and cathode frame are en-closed in a diaphragm bag so as to form a cathode bag assembly, and the cathode bag assemblies and anode plates are arranged in the electrolyte in an electrol-ysis cell in an alternating and consecutive manner.
According to the invention the method includes dispos-ing a gas-sparging means in each of the cathode bag assemblies, and supplying sparging gas to the gas-sparging means such that the gas-sparging means forms a curtain of fine sparging gas bubbles to flush the cathode plate.
A second aspect of the present invention is a cathode frame configured to retain a cathode plate and a dia-phragm bag which encloses said cathode plate inside said cathode frame to form a cathodic compartment in-side the diaphragm bag.
According to the invention the cathode frame comprises a gas-sparging means for flushing the cathode plate with a curtain of fine sparging gas bubbles inside the cathodic compartment.
The advantage of the invention is that the sparged gas bubbles arising along the cathode plate surfaces de-crease the Nernst diffusion layer and thereby increase the limiting current enabling a high current density.
With the high current density, a high delta-Me or anolyte acid concentration can be achieved and less electrolytic cells leading to a lower capital expendi-ture for the tankhouse. Despite the high current den-sity it is possible to achieve a very smooth cathode deposit surface, i.e. high quality cathode is achieved. Nodular growth and torn bags are signifi-cantly reduced thereby reducing the number of short-cuts and leading to a high current density and low op-erating expenses. The bubbles also improve mixing of electrolyte inside the diaphragm bag.
In an embodiment of the invention, the method further includes disposing an electrolyte feed means in each of the cathode bag assemblies, and supplying electro-lyte to the electrolyte feed means to feed electrolyte into the cathode bag. The gas-sparging allows that electrowinning can be operated at a high current den-sity and therefore the electrolyte feed does not need to be excessively reduced in order to achieve a high delta-Me.
In an embodiment of the invention, the gas-sparging means comprises a gas delivery manifold with a plural-ity of outlet orifices, said gas delivery manifold be-ing located at a distance below the cathode plate.
In an embodiment of the invention, the cathode frame comprises an electrolyte feed means integrated to the cathode frame for feeding of the electrolyte into the cathodic compartment.
In an embodiment of the invention, the electrolyte feed means comprises an electrolyte feed manifold lo-cated adjacent the gas delivery manifold.
In an embodiment of the invention, the electrolyte feed manifold is located below the gas delivery mani-fold.
FRAME
FIELD OF THE INVENTION
The present invention relates to a method of operating an electrolysis cell in electrowinning of metal, wherein cathode plates are arranged in cathode frames.
The cathode plate and the cathode frame are enclosed in a diaphragm bag so as to form a cathode bag assem-bly. The cathode bag assemblies and anode plates are arranged in the electrolyte in an electrolysis cell in an alternating and consecutive manner. Further, the invention relates to a cathode frame configured to re-tain a cathode plate and a diaphragm bag which enclos-es said cathode plate inside said cathode frame to form a cathodic compartment inside the diaphragm bag.
BACKGROUND OF THE INVENTION
Electrowinning is a process where a metal dissolved in an electrolyte is reduced on a cathode by means of electric current. Electrowinning takes place in an electrolytic cell that contains a number of anodes and a number of cathodes arranged in an alternating man-ner.
When an electric current is conducted to the electrol-ysis system, metal is precipitated on the surface of the cathode and oxygen is generated on the anodes when the water decomposes, acid and oxygen are formed on the anodes, according to the reaction equations (1) and (2):
Anodic reaction: H20 , 2H+ + 1402 + 2e- (1) (1) Cathodic reaction: Mez+ + ze- ' Me (2) Me = metal, such as Ni, Co, Mn or Cu wherein z = the charge of a metal ion A diaphragm technique can be used in electrowinning metals, which in the electrochemical series are less noble than hydrogen, eg. Ni, Co, Mn. The overpotential of the reduction of these metals is higher than that of hydrogen, which is why the development of hydrogen at a low pH should be avoided by separating the anolyte and the catholyte from each other by a material that perme-ates the electrolyte in a controlled manner, such as a diaphragm fabric, and the electrolyte should flow from the catholyte compartment to the anolyte compartment.
Typically, in sulphate-based nickel, manganese and co-balt electrowinning, said metal can be recovered using divided-cell electrowinning technology, i.e. where the anode and cathode compartments in the cell are sepa-rated appropriately. In such tankhouses, the solution surrounding the cathode (catholyte) is separated from the adjacent anodes in the cell by slotting each cath-ode into a suitable frame, over which a bag of dia-phragm material is stretched. The diaphragm material of the bag permeates the electrolyte in a controlled manner.
A typical target in nickel electrowinning is to have a high delta-Ni (also known as bite i.e. difference in Ni concentrations between the electrolyte fed to the electrolysis cell and electrolyte overflown from the cell), or a high anolyte sulfuric acid concentration.
The higher the delta-Ni, the more economic is the pro-cess since no excess circulation in the leaching SX-EW-circuit exists. When said cathode bag technology (cathodes are in bags in order to keep catholyte pH
high enough for the Ni-EW process) is used, delta-Ni can be increased by two ways, by 1) increasing the current density 2) decreasing the electrolyte flow rate to the cathode bag and consequently through the diaphragm used to separate anodic and cathodic compartment from each other.
In nickel electrowinning, increasing current density is limited at the typical industrial conditions and not much higher than 200 A/m2 can be used without se-rious problems in cathode quality. Increasing current density causes increased nodular growth of metal at the lower end of the cathode. Heavy nodular growth may tear the bag. A torn bag allows acid to migrate into the catholyte compartment thus suppressing the pH to a level at which hydrogen is produced. This causes pit-ting on the cathode surface resulting in a rough sur-face. Hydrogen formation causes also a risk of explo-sion. Nodular growth of the cathode tearing the bag may also cause a shortcut to the neighboring anode thereby decreasing the current efficiency.
Another possibility is to decrease the electrolyte flow through the diaphragm bags. However, when cathode bags are used this option is not possible since it is difficult to distribute even flow over the tankhouse and in addition, the electrolyte retention time inside the diaphragm bag would be very long and electrolyte flow/circulation (inside the bag) would be too slow.
Also temperature control is difficult with slow elec-trolyte flow.
In prior art, as is known from documents WO
2005/019502 Al, US 3,959,112, US 6,849,172 B2 and ar-ticle "Gas bubble induced mixing in electrowinning baths" G. D. Rigby; P. E. Grazier, A. D. Stuart, E. P.
Smithson; Chemical Engineering Science 56 (2001) 6329-6336, gas-sparging has been utilized in copper elec-trowinning to obtain higher current density and to produce high quality metal cathode. It is known that the gas bubbles arising along the electrode surface decrease the Nernst diffusion layer and thereby in-crease the limiting current density (and the critical current density). Thereby a higher current density is possible to be used without decreasing the surface quality of the deposit on the electrode. Typically, in prior art, a gas-sparging manifold has been arranged at the bottom of the electrolysis cell. However, this kind of arrangement of the gas-sparging manifold at the bottom of the cell is not usable in the cathode bag technology since the diaphragm prevents the bub-bles from reaching the cathode.
Therefore, an object of the present invention is to alleviate the problems described above and to intro-duce a method of operating an electrolysis cell and a cathode frame that allow the electrowinning to be op-erated at a high current density and at the same time to achieve a high quality cathode deposit with a smooth surface and with a minimum amount of nodular growth.
Further, the object of the invention is to introduce a method of operating an electrolysis cell and a cathode frame that allow to achieve a high delta-Me (differ-ence in the metal concentrations between the electro-lyte fed to the cell and electrolyte overflown from the cell) whereby less cells are needed to obtain the same capacity.
Further, the object of the invention is to introduce a method of operating an electrolysis cell and a cathode frame that minimize the number of torn cathode bags and short-cuts and therefore to achieve a high current efficiency.
Further, the object of the invention is to introduce a method of operating an electrolysis cell and a cathode frame that allow a good mixing of the electrolyte re-sulting in a homogenous electrolyte inside the cathode 5 bag.
SUMMARY OF THE INVENTION
A first aspect of the present invention is a method of operating an electrolysis cell in electrowinning of metal, wherein cathode plates are arranged in cathode frames and the cathode plate and cathode frame are en-closed in a diaphragm bag so as to form a cathode bag assembly, and the cathode bag assemblies and anode plates are arranged in the electrolyte in an electrol-ysis cell in an alternating and consecutive manner.
According to the invention the method includes dispos-ing a gas-sparging means in each of the cathode bag assemblies, and supplying sparging gas to the gas-sparging means such that the gas-sparging means forms a curtain of fine sparging gas bubbles to flush the cathode plate.
A second aspect of the present invention is a cathode frame configured to retain a cathode plate and a dia-phragm bag which encloses said cathode plate inside said cathode frame to form a cathodic compartment in-side the diaphragm bag.
According to the invention the cathode frame comprises a gas-sparging means for flushing the cathode plate with a curtain of fine sparging gas bubbles inside the cathodic compartment.
The advantage of the invention is that the sparged gas bubbles arising along the cathode plate surfaces de-crease the Nernst diffusion layer and thereby increase the limiting current enabling a high current density.
With the high current density, a high delta-Me or anolyte acid concentration can be achieved and less electrolytic cells leading to a lower capital expendi-ture for the tankhouse. Despite the high current den-sity it is possible to achieve a very smooth cathode deposit surface, i.e. high quality cathode is achieved. Nodular growth and torn bags are signifi-cantly reduced thereby reducing the number of short-cuts and leading to a high current density and low op-erating expenses. The bubbles also improve mixing of electrolyte inside the diaphragm bag.
In an embodiment of the invention, the method further includes disposing an electrolyte feed means in each of the cathode bag assemblies, and supplying electro-lyte to the electrolyte feed means to feed electrolyte into the cathode bag. The gas-sparging allows that electrowinning can be operated at a high current den-sity and therefore the electrolyte feed does not need to be excessively reduced in order to achieve a high delta-Me.
In an embodiment of the invention, the gas-sparging means comprises a gas delivery manifold with a plural-ity of outlet orifices, said gas delivery manifold be-ing located at a distance below the cathode plate.
In an embodiment of the invention, the cathode frame comprises an electrolyte feed means integrated to the cathode frame for feeding of the electrolyte into the cathodic compartment.
In an embodiment of the invention, the electrolyte feed means comprises an electrolyte feed manifold lo-cated adjacent the gas delivery manifold.
In an embodiment of the invention, the electrolyte feed manifold is located below the gas delivery mani-fold.
In an embodiment of the invention, the cathode frame comprises - a vertical first side member having an up-per end and a lower end, - a first guide arranged at the first side member between the upper end and the lower end of the first side member to provide vertical guidance and lateral support for a first edge of the cathode plate, - a vertical second side member at a distance from the first side member, said second side member having an upper end and a lower end, - a second guide arranged at the second side member between the upper end and the lower end of the first side member to provide vertical guidance and lateral support for a second edge of the cathode plate, - hangers at the upper ends of the first and second side member, said hangers being adapted to hang the cathode frame to the support of the opposite walls of the electrolysis cell, and - a horizontal bottom member extending be-tween and rigidly connecting the lower ends of the first and second side members, whereby the gas deliv-ery manifold is arranged to extend between the side members on and along the bottom member.
In an embodiment of the invention, the cathode frame comprises a stop member arranged at each of the first and second side members, against which stop members the lower end of the cathode plate may abut, said stop members being arranged to keep the lower end of the cathode plate at a distance from the gas delivery man-ifold In an embodiment of the invention, the cathode frame comprises gas inlet channel arranged to supply pres-surized gas to the gas delivery manifold.
In an embodiment of the invention, the gas outlet ori-fices are disposed at the upper part of the gas deliv-ery manifold to direct the delivery of bubbles to an upwards direction. The aim is that all gas bubbles go directly upwards so that collisions and fusion of gas bubbles to larger bubbles on the gas delivery manifold are prevented so as to maintain the small size of the gas bubbles.
In an embodiment of the invention, the first guide and the second guide are disposed to center the cathode plate in the middle of the gas delivery manifold so that substantially an equal amount of fine bubbles uniformly flush each one of the opposite surfaces of the cathode plate.
In an embodiment of the invention, the cathode frame comprises a pair of cross-bars arranged adjacent the upper end of the cathode frame, each one of said cross-bars having a first end connected to the first side member and the a second end connected to the sec-ond side member.
In an embodiment of the invention, the cross-bars com-prise fastening members by which the diaphragm bag can be releasably fastened to the cathode frame.
In an embodiment of the invention, the gas delivery manifold is a gas permeable tube, the lower part of the tube being deposited with a gas impermeable mate-rial.
In an embodiment of the invention, the cathode frame comprises a stop member arranged at each of the first and second side members, against which stop members the lower end of the cathode plate may abut, said stop members being arranged to keep the lower end of the cathode plate at a distance from the gas delivery man-ifold In an embodiment of the invention, the cathode frame comprises gas inlet channel arranged to supply pres-surized gas to the gas delivery manifold.
In an embodiment of the invention, the gas outlet ori-fices are disposed at the upper part of the gas deliv-ery manifold to direct the delivery of bubbles to an upwards direction. The aim is that all gas bubbles go directly upwards so that collisions and fusion of gas bubbles to larger bubbles on the gas delivery manifold are prevented so as to maintain the small size of the gas bubbles.
In an embodiment of the invention, the first guide and the second guide are disposed to center the cathode plate in the middle of the gas delivery manifold so that substantially an equal amount of fine bubbles uniformly flush each one of the opposite surfaces of the cathode plate.
In an embodiment of the invention, the cathode frame comprises a pair of cross-bars arranged adjacent the upper end of the cathode frame, each one of said cross-bars having a first end connected to the first side member and the a second end connected to the sec-ond side member.
In an embodiment of the invention, the cross-bars com-prise fastening members by which the diaphragm bag can be releasably fastened to the cathode frame.
In an embodiment of the invention, the gas delivery manifold is a gas permeable tube, the lower part of the tube being deposited with a gas impermeable mate-rial.
In an embodiment of the invention, the gas permeable upper part of the gas permeable tube is covered with material which improves the breakdown of the bubbles discharged from the orifices to smaller bubbles.
In an embodiment of the invention, the cathode frame comprises a cap which is releasably and gas-tightly connectable to the cathode frame, and that the cap comprises a central slot through which the cathode plate is sealably insertable to and removable from the frame.
In an embodiment of the invention, the cap comprises a suction pipe for removal of the sparged gas from in-side the bag.
The method and the cathode frame having the gas-sparging means according to the invention can be used in any electrowinning process that needs separation of the catholyte (electrolyte inside the cathode bag) and the anolyte (electrolyte in the cell space surrounding the cathode bags). Thus, the method and the cathode frame of the invention are usable in the elec-trowinning of nickel, manganese and cobalt. Further, the method and the cathode frame are also usable in the electrowinning of copper. Further, it is also usa-ble in the electrowinning of gold and silver.
It is to be understood that the aspects and embodi-ments of the invention described above may be used in any combination with each other. Several of the as-pects and embodiments may be combined together to form a further embodiment of the invention. A method for electrowinning or a cathode frame which is an aspect of the invention may comprise at least one of the em-bodiments of the invention described above.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are included to pro-vide a further understanding of the invention and constitute a part of this specification, illustrate 5 embodiments of the invention and together with the de-scription help to explain the principles of the inven-tion. In the drawings:
Fig. 1 schematically shows an exploded view of a cath-10 ode bag assembly including a cathode frame according to one embodiment of the invention, a cathode plate insertable to the frame and a diaphragm bag configured to be drawn on the frame;
Fig. 2 shows one embodiment of the cathode bag assem-bly assembled from the parts shown in Fig. 1;
Figs. 3 shows another embodiment of the cathode frame having both the gas-sparging and electrolyte feed means integrated into the cathode frame;
Fig. 4 schematically shows a cross-sectional view of the cathode bag assembly immersed in the electrolyte and the gas-sparging means sparging fine bubbles along the cathode plate surfaces;
Fig. 5 shows a cross-section of the gas delivery mani-fold of one embodiment of the invention;
Fig. 6 schematically shows an electrolysis cell equipped with the cathode bag assemblies having cath-ode frames of Fig. 2 and anode plates arranged in the cell.
In an embodiment of the invention, the cathode frame comprises a cap which is releasably and gas-tightly connectable to the cathode frame, and that the cap comprises a central slot through which the cathode plate is sealably insertable to and removable from the frame.
In an embodiment of the invention, the cap comprises a suction pipe for removal of the sparged gas from in-side the bag.
The method and the cathode frame having the gas-sparging means according to the invention can be used in any electrowinning process that needs separation of the catholyte (electrolyte inside the cathode bag) and the anolyte (electrolyte in the cell space surrounding the cathode bags). Thus, the method and the cathode frame of the invention are usable in the elec-trowinning of nickel, manganese and cobalt. Further, the method and the cathode frame are also usable in the electrowinning of copper. Further, it is also usa-ble in the electrowinning of gold and silver.
It is to be understood that the aspects and embodi-ments of the invention described above may be used in any combination with each other. Several of the as-pects and embodiments may be combined together to form a further embodiment of the invention. A method for electrowinning or a cathode frame which is an aspect of the invention may comprise at least one of the em-bodiments of the invention described above.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are included to pro-vide a further understanding of the invention and constitute a part of this specification, illustrate 5 embodiments of the invention and together with the de-scription help to explain the principles of the inven-tion. In the drawings:
Fig. 1 schematically shows an exploded view of a cath-10 ode bag assembly including a cathode frame according to one embodiment of the invention, a cathode plate insertable to the frame and a diaphragm bag configured to be drawn on the frame;
Fig. 2 shows one embodiment of the cathode bag assem-bly assembled from the parts shown in Fig. 1;
Figs. 3 shows another embodiment of the cathode frame having both the gas-sparging and electrolyte feed means integrated into the cathode frame;
Fig. 4 schematically shows a cross-sectional view of the cathode bag assembly immersed in the electrolyte and the gas-sparging means sparging fine bubbles along the cathode plate surfaces;
Fig. 5 shows a cross-section of the gas delivery mani-fold of one embodiment of the invention;
Fig. 6 schematically shows an electrolysis cell equipped with the cathode bag assemblies having cath-ode frames of Fig. 2 and anode plates arranged in the cell.
DETAILED DESCRIPTION OF THE INVENTION
Reference will now be made in detail to the embodi-ments of the present invention, examples of which are illustrated in the accompanying drawings.
Figure 1 shows a cathode frame 2 which is configured to hold a cathode plate 1 and a diaphragm bag 3. In Figure 1 cathode plate 1 and the diaphragm bag 3 are shown separate from the cathode frame 2. The cathode frame 2 with the cathode plate 1 installed in the cathode frame 2 can be inserted inside the diaphragm bag 3 so that the diaphragm bag 3 encloses the cathode frame in a manner as shown in Fig. 2. The cathode plate 1 can be either a starter sheet or a permanent cathode.
The cathode frame 2 comprises a gas-sparging means 6.
The gas-sparging means comprises a gas delivery mani-fold 6 having a plurality of outlet orifices 8 through which the sparging gas can be distributed to the elec-trolyte in the cathodic compartment inside the dia-phragm bag 3 as a cloud of fine bubbles which rise as a curtain along the surface of the cathode plate 1 as illustrated in Fig. 4. Pressurized gas may be supplied to the gas delivery manifold 6 via a gas inlet channel 16. The gas outlet orifices 8 are disposed at the up-per part of the gas delivery manifold 6 to allow bub-ble delivery only in an upwards direction. The gas outlet orifices 8 have a diameter smaller than 3 mm.
With reference to Fig. 5, in one example, the gas de-livery manifold 6 may be made of a gas permeable tube, so that only the lower part of the tube is deposited with a gas impermeable material 19 and the upper part of the tube is left undeposited for discharging the sparging gas in an upwards direction. The gas imperme-able material 19 can be any suitable gas impermeable material, such as a layer of paint, lacquer, glue or polymer. The gas permeable upper part of the gas per-meable tube 6 may also be covered with material 24, such as industrial fabric, which improves the break-down of the bubbles discharged from the orifices 8 to even smaller bubbles.
Referring to Fig. 1, the cathode frame 2 comprises a vertical first side member 9 having an upper end and a lower end. A first guide 10 is arranged at the first side member 9 between the upper end and the lower end of the first side member to provide vertical guidance and lateral support for a first edge of the cathode plate. The cathode frame 2 comprises a vertical second side member 11 at a distance from the first side mem-ber, said second side member having an upper end and a lower end. A second guide 12 is arranged at the second side member 11 between the upper end and the lower end of the first side member to provide vertical guidance and lateral support for a second edge of the cathode plate. A horizontal bottom member 14 extends between and rigidly connecting the lower ends of the first and second side members 9, 11 so that the cathode frame 2 is substantially a U-shaped rigid structure. The cath-ode frame 2 can be made of suitable polymer material reinforced with steel inside the polymer material.
The gas delivery manifold 6 extends between the side members 9, 11 on and along the bottom member 14. The cathode frame 2 comprises a stop member 15 which is arranged oppositely at the first and second side mem-bers 9, 11 so that the lower end of the cathode plate 1 may abut against the stop members 15. The stop mem-bers 15 being are arranged to keep the lower end of the cathode plate at a distance h from the gas deliv-ery manifold 6 so that the cathode plate 2 never con-tacts the gas delivery manifold 6 when the cathode plate 1 is installed in the cathode frame 2 (see Figs.
2 and 4).
As shown in Fig. 2 and Fig. 4, the first guide 10 and the second guide 12 are disposed to center the cathode plate 1 in the middle of the gas delivery manifold 6 so that substantially an equal amount of fine bubbles uniformly flush each one of the opposite surfaces of the cathode plate 1.
As shown in Figs 1, 2, and Fig 6, the cathode frame 2 comprises a pair of hangers 13 at the upper ends of the first and second side member 9. 11. The hangers are adapted to hang the cathode frame 2 to the support of the opposite walls of the electrolysis cell 5.
As shown in Figs. 1 and 2, the cathode frame 2 may al-so comprise a pair of cross-bars 17 arranged adjacent the upper end of the cathode frame 2. The number of cross-bars can also more than two, if needed. The cross-bars 17 have a first end connected to the first side member 9 and a second end connected to the second side member 11. The cross-bars 17 strengthen the structure of the cathode frame 2.
The cross-bars 17 may also serve in fastening the dia-phragm bag to the frame 2. Then the cross-bars 17 may comprise fastening members 18 by which the diaphragm bag 3 can be releasably fastened to the cathode frame 2. For example, the fastening members 18 may comprise a plurality of lugs to which the diaphragm bag 3 can be hanged, as shown in Fig. 2. In another embodiment the fastening members 18 can be e.g. cable ties or like straps (not shown) by which the diaphragm bag 3 can be hanged to the cross-bars 17. Also any other way known to the man skilled in the art may be used for of fastening the diaphragm bag to the cathode frame.
Reference will now be made in detail to the embodi-ments of the present invention, examples of which are illustrated in the accompanying drawings.
Figure 1 shows a cathode frame 2 which is configured to hold a cathode plate 1 and a diaphragm bag 3. In Figure 1 cathode plate 1 and the diaphragm bag 3 are shown separate from the cathode frame 2. The cathode frame 2 with the cathode plate 1 installed in the cathode frame 2 can be inserted inside the diaphragm bag 3 so that the diaphragm bag 3 encloses the cathode frame in a manner as shown in Fig. 2. The cathode plate 1 can be either a starter sheet or a permanent cathode.
The cathode frame 2 comprises a gas-sparging means 6.
The gas-sparging means comprises a gas delivery mani-fold 6 having a plurality of outlet orifices 8 through which the sparging gas can be distributed to the elec-trolyte in the cathodic compartment inside the dia-phragm bag 3 as a cloud of fine bubbles which rise as a curtain along the surface of the cathode plate 1 as illustrated in Fig. 4. Pressurized gas may be supplied to the gas delivery manifold 6 via a gas inlet channel 16. The gas outlet orifices 8 are disposed at the up-per part of the gas delivery manifold 6 to allow bub-ble delivery only in an upwards direction. The gas outlet orifices 8 have a diameter smaller than 3 mm.
With reference to Fig. 5, in one example, the gas de-livery manifold 6 may be made of a gas permeable tube, so that only the lower part of the tube is deposited with a gas impermeable material 19 and the upper part of the tube is left undeposited for discharging the sparging gas in an upwards direction. The gas imperme-able material 19 can be any suitable gas impermeable material, such as a layer of paint, lacquer, glue or polymer. The gas permeable upper part of the gas per-meable tube 6 may also be covered with material 24, such as industrial fabric, which improves the break-down of the bubbles discharged from the orifices 8 to even smaller bubbles.
Referring to Fig. 1, the cathode frame 2 comprises a vertical first side member 9 having an upper end and a lower end. A first guide 10 is arranged at the first side member 9 between the upper end and the lower end of the first side member to provide vertical guidance and lateral support for a first edge of the cathode plate. The cathode frame 2 comprises a vertical second side member 11 at a distance from the first side mem-ber, said second side member having an upper end and a lower end. A second guide 12 is arranged at the second side member 11 between the upper end and the lower end of the first side member to provide vertical guidance and lateral support for a second edge of the cathode plate. A horizontal bottom member 14 extends between and rigidly connecting the lower ends of the first and second side members 9, 11 so that the cathode frame 2 is substantially a U-shaped rigid structure. The cath-ode frame 2 can be made of suitable polymer material reinforced with steel inside the polymer material.
The gas delivery manifold 6 extends between the side members 9, 11 on and along the bottom member 14. The cathode frame 2 comprises a stop member 15 which is arranged oppositely at the first and second side mem-bers 9, 11 so that the lower end of the cathode plate 1 may abut against the stop members 15. The stop mem-bers 15 being are arranged to keep the lower end of the cathode plate at a distance h from the gas deliv-ery manifold 6 so that the cathode plate 2 never con-tacts the gas delivery manifold 6 when the cathode plate 1 is installed in the cathode frame 2 (see Figs.
2 and 4).
As shown in Fig. 2 and Fig. 4, the first guide 10 and the second guide 12 are disposed to center the cathode plate 1 in the middle of the gas delivery manifold 6 so that substantially an equal amount of fine bubbles uniformly flush each one of the opposite surfaces of the cathode plate 1.
As shown in Figs 1, 2, and Fig 6, the cathode frame 2 comprises a pair of hangers 13 at the upper ends of the first and second side member 9. 11. The hangers are adapted to hang the cathode frame 2 to the support of the opposite walls of the electrolysis cell 5.
As shown in Figs. 1 and 2, the cathode frame 2 may al-so comprise a pair of cross-bars 17 arranged adjacent the upper end of the cathode frame 2. The number of cross-bars can also more than two, if needed. The cross-bars 17 have a first end connected to the first side member 9 and a second end connected to the second side member 11. The cross-bars 17 strengthen the structure of the cathode frame 2.
The cross-bars 17 may also serve in fastening the dia-phragm bag to the frame 2. Then the cross-bars 17 may comprise fastening members 18 by which the diaphragm bag 3 can be releasably fastened to the cathode frame 2. For example, the fastening members 18 may comprise a plurality of lugs to which the diaphragm bag 3 can be hanged, as shown in Fig. 2. In another embodiment the fastening members 18 can be e.g. cable ties or like straps (not shown) by which the diaphragm bag 3 can be hanged to the cross-bars 17. Also any other way known to the man skilled in the art may be used for of fastening the diaphragm bag to the cathode frame.
Fig. 3 shows a further modification of the cathode frame 2 of Fig. 1. In this embodiment the cathode frame 2 comprises a gas-sparging means 6 as disclosed above with reference to Fig. 1, 2, 3 and 5, and also an electrolyte feed means 7 integrated to the cathode frame 2 for feeding of the electrolyte into the ca-thodic compartment inside the bag 3. The electrolyte feed means comprises an electrolyte feed manifold 7 located adjacent and below the gas delivery manifold 6. As an alternative to Fig. 3, the gas delivery man-ifold 6 of Fig. 1 can also be used to deliver electro-lyte into the bag 3. A simultaneous feeding of both sparging gas and electrolyte via the gas delivery man-ifold 6 is also possible.
In another embodiment (not shown in Figs.) the gas de-livery manifold 6 (and the electrolyte feed manifold 7 and the bottom member 14 of the frame 2 are all inte-grated into an integral structure. The side members 9, 11 may also include shading elements that shade the flow so that the metal precipitating on the cathode surface does not grow on edge regions of the cathode plate 1 and get stuck with the guides 12.
Fig. 4 shows that the cathode frame 2 may also com-prise a cap 20 which is releasably and gas-tightly connectable to top of the cathode frame 2. The cap 20 comprises a central slot 21 through which the cath-ode plate 1 is sealably insertable to and removable from the frame. The sparged gas which is collected to a space limited by the cap 20 and the electrolyte sur-face may be suctioned by a suction pipe 22 for removal of the sparged gas from inside the bag 3.
With reference to Fig. 6, the arrangement as disclosed above with reference to Figs. 1 to 5, is used in elec-trowinning of metal, wherein cathode plates 1 are ar-ranged in cathode frames 2 and the cathode plate and cathode frame are enclosed in a diaphragm bag 3 so as to form a cathode bag assembly as shown on Fig. 2.
5 These cathode bag assemblies and anode plates 4 are arranged in the electrolyte in an electrolysis cell 5 in an alternating and consecutive manner. The neces-sary busbars arranged to supply electric current are not shown in Fig. 6. The busbars may be arranged in 10 any way known to a man skilled in the art. Sparging gas is supplied to the gas-sparging means 6 such that a curtain of fine sparging gas bubbles is formed to flush the cathode plate 1. Also electrolyte may be supplied to the electrolyte feed means 7 to feed elec-15 trolyte into the cathode bag assembly. A tube 23 for supplying and distributing sparging gas, resp. elec-trolyte, to the gas-sparging means 6, resp. to elec-trolyte feed means 7, is preferable disposed outside the cell 5 beside the side wall of the cell as sche-matically illustrated in Fig. 6.
Example In order to show the effects of gas-sparging in con-junction with cathode frame tests were conducted in a laboratory scale electrolysis cell configured for nickel electrowinning. Air was used as the sparging gas. The current density was 300 A/m2 while normally in the nickel electrowinning a current density much more than 200 A/m2 cannot be used without problems in cathode quality when the arrangement of the invention is not used. The cathode frame having a structure as shown in Fig. 1 was used in tests. The gas delivery manifold in the bottom of the cathode frame was made of soaking hose which is a porous air permeable tube.
The soaking hose was treated with gas impermeable glue substantially in the manner as disclosed with refer-ence to Fig. 4 so that the air bubbles would be re-leased upwards from the upper part of the hose. The frame was equipped with an air inlet pipe to supply air to the gas delivery hose and cathode guides/holders to keep the cathode in position under sparging and stoppers that kept the bottom edge of the cathode from a distance of the hose. The cell was ac-commodated in a water bath to keep the electrolyte temperature constant. Catholyte was pumped into the cell (volume 3.5 1) inside a diaphragm bag that iso-lated catholyte from the anolyte. Anolyte was collect-ed as overflow. A nickel starter sheet was used as a cathode and two anodes were Pb-Ag (Ag 0.5%) (size 7.8 cm x 9.0 cm) with the spacing between anodes of 110 mm and hydrostatic head of 20 mm. Hydrostatic head is the height difference between anolyte surface and catho-lyte surface (see also Fig. 4; Catholyte surface is at a higher level than the anolyte surface and therefore the flow of the electrolyte is in the direction from the cathodic compartment (inside cathode bag) to the anodic compartment (outside cathode bag)). Air was sparged 300 ml/min and 2.2 g/1 Na-laurylsulfate was used as an additive. The nickel cathodes produced at 300 A/m2 had very smooth surfaces. No pitting on the cathode surfaces due to the hydrogen formation was present demonstrating an additional beneficial effect of the air sparging in Ni-EW. Based on the experiment the current density can be increased by using the air sparging at least to 300 A/m2 and very smooth deposit surface can be produced. Furthermore, no short-cuts were detected and it seems that gas sparging also re-duces the tendency to obtain short circuits reducing the number of torn bags in the Ni-EW process.
A further modification of the invention may also be to integrate the gas-sparging means to an anode frame.
The anode bag assembly comprises and anode frame into which an anode can be placed and a diaphragm bag is installed to enclose these. A gas-sparging means may be integrated to the anode frame in a manner that the gas sparging means is located outside the anode bag so that the gas-sparging means may be positioned right below the neighboring adjacent cathode plate to sparge gas as fine bubbles to flush the cathode plate.
While the present inventions have been described in connection with a number of exemplary embodiments, and implementations, the present inventions are not so limited, but rather cover various modifications, and equivalent arrangements, which fall within the purview of prospective claims.
In another embodiment (not shown in Figs.) the gas de-livery manifold 6 (and the electrolyte feed manifold 7 and the bottom member 14 of the frame 2 are all inte-grated into an integral structure. The side members 9, 11 may also include shading elements that shade the flow so that the metal precipitating on the cathode surface does not grow on edge regions of the cathode plate 1 and get stuck with the guides 12.
Fig. 4 shows that the cathode frame 2 may also com-prise a cap 20 which is releasably and gas-tightly connectable to top of the cathode frame 2. The cap 20 comprises a central slot 21 through which the cath-ode plate 1 is sealably insertable to and removable from the frame. The sparged gas which is collected to a space limited by the cap 20 and the electrolyte sur-face may be suctioned by a suction pipe 22 for removal of the sparged gas from inside the bag 3.
With reference to Fig. 6, the arrangement as disclosed above with reference to Figs. 1 to 5, is used in elec-trowinning of metal, wherein cathode plates 1 are ar-ranged in cathode frames 2 and the cathode plate and cathode frame are enclosed in a diaphragm bag 3 so as to form a cathode bag assembly as shown on Fig. 2.
5 These cathode bag assemblies and anode plates 4 are arranged in the electrolyte in an electrolysis cell 5 in an alternating and consecutive manner. The neces-sary busbars arranged to supply electric current are not shown in Fig. 6. The busbars may be arranged in 10 any way known to a man skilled in the art. Sparging gas is supplied to the gas-sparging means 6 such that a curtain of fine sparging gas bubbles is formed to flush the cathode plate 1. Also electrolyte may be supplied to the electrolyte feed means 7 to feed elec-15 trolyte into the cathode bag assembly. A tube 23 for supplying and distributing sparging gas, resp. elec-trolyte, to the gas-sparging means 6, resp. to elec-trolyte feed means 7, is preferable disposed outside the cell 5 beside the side wall of the cell as sche-matically illustrated in Fig. 6.
Example In order to show the effects of gas-sparging in con-junction with cathode frame tests were conducted in a laboratory scale electrolysis cell configured for nickel electrowinning. Air was used as the sparging gas. The current density was 300 A/m2 while normally in the nickel electrowinning a current density much more than 200 A/m2 cannot be used without problems in cathode quality when the arrangement of the invention is not used. The cathode frame having a structure as shown in Fig. 1 was used in tests. The gas delivery manifold in the bottom of the cathode frame was made of soaking hose which is a porous air permeable tube.
The soaking hose was treated with gas impermeable glue substantially in the manner as disclosed with refer-ence to Fig. 4 so that the air bubbles would be re-leased upwards from the upper part of the hose. The frame was equipped with an air inlet pipe to supply air to the gas delivery hose and cathode guides/holders to keep the cathode in position under sparging and stoppers that kept the bottom edge of the cathode from a distance of the hose. The cell was ac-commodated in a water bath to keep the electrolyte temperature constant. Catholyte was pumped into the cell (volume 3.5 1) inside a diaphragm bag that iso-lated catholyte from the anolyte. Anolyte was collect-ed as overflow. A nickel starter sheet was used as a cathode and two anodes were Pb-Ag (Ag 0.5%) (size 7.8 cm x 9.0 cm) with the spacing between anodes of 110 mm and hydrostatic head of 20 mm. Hydrostatic head is the height difference between anolyte surface and catho-lyte surface (see also Fig. 4; Catholyte surface is at a higher level than the anolyte surface and therefore the flow of the electrolyte is in the direction from the cathodic compartment (inside cathode bag) to the anodic compartment (outside cathode bag)). Air was sparged 300 ml/min and 2.2 g/1 Na-laurylsulfate was used as an additive. The nickel cathodes produced at 300 A/m2 had very smooth surfaces. No pitting on the cathode surfaces due to the hydrogen formation was present demonstrating an additional beneficial effect of the air sparging in Ni-EW. Based on the experiment the current density can be increased by using the air sparging at least to 300 A/m2 and very smooth deposit surface can be produced. Furthermore, no short-cuts were detected and it seems that gas sparging also re-duces the tendency to obtain short circuits reducing the number of torn bags in the Ni-EW process.
A further modification of the invention may also be to integrate the gas-sparging means to an anode frame.
The anode bag assembly comprises and anode frame into which an anode can be placed and a diaphragm bag is installed to enclose these. A gas-sparging means may be integrated to the anode frame in a manner that the gas sparging means is located outside the anode bag so that the gas-sparging means may be positioned right below the neighboring adjacent cathode plate to sparge gas as fine bubbles to flush the cathode plate.
While the present inventions have been described in connection with a number of exemplary embodiments, and implementations, the present inventions are not so limited, but rather cover various modifications, and equivalent arrangements, which fall within the purview of prospective claims.
Claims (15)
1. A cathode frame (2) configured to retain a cathode plate (1) and a diaphragm bag (3) which encloses said cathode plate inside said cathode frame to form a ca-thodic compartment inside the diaphragm bag, the cath-ode frame (2) comprises a gas-sparging means (6) for flushing the cathode plate (1) with a curtain of fine sparging gas bubbles inside the cathodic compartment, the gas-sparging means comprising a gas delivery mani-fold (6) which is located at a distance (h) below the cathode plate (1), characterized in that gas delivery manifold (6) comprises a plurality of outlet orifices (8) disposed at the upper part of the gas de-livery manifold (6) to allow bubble delivery in an up-wards direction.
2. The cathode frame according to claim 1, c h a r acterized in that the cathode frame (2) compris-es an electrolyte feed means (7) integrated to the cathode frame (2) for feeding of the electrolyte into the cathodic compartment.
3. The cathode frame according to claim 2, c h a r acterized in that the electrolyte feed means comprises an electrolyte feed manifold (7) located ad-jacent the gas delivery manifold (6).
4. The cathode frame according to claim 3, c h a r -acterized in that the electrolyte feed manifold (7) is located below the gas delivery manifold (6).
5. The cathode frame according to any one of the claims 1 to 4, characterized. in that the cathode frame (2) comprises - a vertical first side member (9) having an upper end and a lower end, - a first guide (10) arranged at the first side member between the upper end and the lower end of the first side member to provide vertical guidance and lateral support for a first edge of the cathode plate, - a vertical second side member (11) at a distance from the first side member, said second side member having an upper end and a lower end, - a second guide (12) arranged at the second side member between the upper end and the lower end of the first side member to provide vertical guidance and lateral support for a second edge of the cathode plate, - hangers (13) at the upper ends of the first and second side member, said hangers being adapted to hang the cathode frame to the support of the opposite walls of the electrolysis cell, and - a horizontal bottom member (14) extending between and rigidly connecting the lower ends of the first and second side members, whereby the gas deliv-ery manifold (6) is arranged to extend between the ide members (9, 11) on and along the bottom member (14).
6. The cathode frame according to claim 5, char-acterized in that the cathode frame (2) compris-es a stop member (15) arranged at each of the first and second side members (9, 11), against which stop members the lower end of the cathode plate may abut, said stop members being arranged to keep the lower end of the cathode plate at a distance (h) from the gas delivery manifold (6)
7. The cathode frame according to claim 5 or 6, characterized in that the cathode frame (2) comprises a gas inlet channel (16) arranged to supply pressurized gas to the gas delivery manifold (6).
8. The cathode frame according to any one of the claims 5 to 7, characterized in that the first guide (10) and the second guide (12) are dis-posed to center the cathode plate (1) in the middle of the gas delivery manifold (6) so that substantially an equal amount of fine bubbles uniformly flush each one of the opposite surfaces of the cathode plate.
9. The cathode frame according to any one of the claims 5 to 8, characterized in that the cathode frame (2) comprises a pair of cross-bars (17) arranged adjacent the upper end of the cathode frame, each one of said cross-bars having a first end con-nected to the first side member (9) and the a second end connected to the second side member (11).
10. The cathode frame according to claim 9, char acterized in that the cross-bars (17) comprise fastening members (18) by which the diaphragm bag (3) can be releasably fastened to the cathode frame.
11. The cathode frame according to any one of the claims 1 to 10, characterized in that the gas delivery manifold (6) is a gas permeable tube, having a lower part of the tube which is deposited with a gas impermeable material (19).
12. The cathode frame according to claim 11, char-acterized in that the gas permeable upper part of the gas permeable tube (6) is covered with material (24) which improves the breakdown of the bubbles dis-charged from the orifices (8) to smaller bubbles.
13. The cathode frame according to any one of the claims 1 to 12, characterized in that the cathode frame (2) comprises a cap (20) which is re-leasably and gas-tightly connectable to the cathode frame, and that the cap (20) comprises a central slot (21) through which the cathode plate (1) is sealably insertable to and removable from the frame.
14. The cathode frame according to claim 13, char-acterized in that the cap (20) comprises a suc-tion pipe (22) for removal of the sparged gas from in-side the bag.
15. Use of the cathode frame (2) according to any one of the claims 1 to 14 in the electrowinning of any one of the metals including nickel Ni, manganese Mn, co-balt Co, gold Au, silver Ag, copper Cu.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI20125139 | 2012-02-08 | ||
| FI20125139A FI123851B (en) | 2012-02-08 | 2012-02-08 | Cathodram and use of a cathodram |
| PCT/FI2013/050128 WO2013117814A1 (en) | 2012-02-08 | 2013-02-06 | Method of operating an electrolysis cell and cathode frame |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2860814A1 true CA2860814A1 (en) | 2013-08-15 |
| CA2860814C CA2860814C (en) | 2016-07-05 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2860814A Expired - Fee Related CA2860814C (en) | 2012-02-08 | 2013-02-06 | Method of operating an electrolysis cell and cathode frame |
Country Status (7)
| Country | Link |
|---|---|
| CN (1) | CN104160067B (en) |
| BR (1) | BR112014019547A8 (en) |
| CA (1) | CA2860814C (en) |
| EA (1) | EA028294B1 (en) |
| FI (1) | FI123851B (en) |
| WO (1) | WO2013117814A1 (en) |
| ZA (1) | ZA201406117B (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104831322B (en) * | 2014-02-10 | 2017-06-06 | 阳谷祥光铜业有限公司 | Pole plate wash mill |
| TWI553166B (en) * | 2014-04-25 | 2016-10-11 | Electroplating apparatus | |
| CN104532293B (en) * | 2014-12-22 | 2017-06-09 | 无锡市瑞思科环保科技有限公司 | The method of purifying nickel and nickel purifying plant in chemical nickel plating waste solution |
| US10011919B2 (en) * | 2015-05-29 | 2018-07-03 | Lam Research Corporation | Electrolyte delivery and generation equipment |
| CN104928709B (en) * | 2015-06-24 | 2017-04-12 | 广西有色金属集团汇元锰业有限公司 | Electrolytic system of manganese dioxide and production method of manganese dioxide |
| RU2677447C2 (en) * | 2017-02-13 | 2019-01-16 | Лидия Алексеевна Воропанова | Electroextraction of cobalt from aqueous solutions of cobalt and manganese sulfates in dynamic conditions |
| CN107354481A (en) * | 2017-08-30 | 2017-11-17 | 杭州三耐环保科技股份有限公司 | The electrolytic cell of both electrolytic diaphragm frame, supporting construction and application |
| JP6997376B2 (en) * | 2018-05-22 | 2022-01-17 | 日本電信電話株式会社 | Carbon dioxide reduction device |
| CN111286762B (en) * | 2020-03-26 | 2022-03-11 | 江西铜业（清远）有限公司 | Cathode copper starting sheet guider |
| CN112707010A (en) * | 2021-01-16 | 2021-04-27 | 盐城市电子设备厂有限公司 | Loading platform for carrying cathode plate |
| CN113013479A (en) * | 2021-01-26 | 2021-06-22 | 万向一二三股份公司 | Capacity-increasing soft-package lithium battery structure and battery cell combination method thereof |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB543294A (en) * | 1939-07-12 | 1942-02-18 | Falconbridge Nickel Mines Ltd | Electrolytic production of nickel |
| GB1440072A (en) * | 1972-06-02 | 1976-06-23 | Cjb Developments Ltd | Electrolytic cells time synchronisation particularly for seismic work |
| CA1020115A (en) * | 1973-02-09 | 1977-11-01 | Victor A. Ettel | Air sparging electrowinning cell |
| CA1125228A (en) * | 1979-10-10 | 1982-06-08 | Daniel P. Young | Process for electrowinning nickel or cobalt |
| JP3173689B2 (en) * | 1993-07-26 | 2001-06-04 | 住友金属鉱山株式会社 | Cathode box for metal electrolytic scouring |
| CN100525585C (en) * | 2004-08-26 | 2009-08-05 | 日本特殊陶业株式会社 | Manufacturing methods and electroless plating apparatus for manufacturing wiring circuit boards |
| FR2938498B1 (en) * | 2008-11-17 | 2012-02-03 | Gaztransp Et Technigaz | SHIP OR FLOATING SUPPORT EQUIPPED WITH A DEVICE FOR ATTENUATING THE MOVEMENTS OF LIQUID CARENES |
| CN102283421B (en) * | 2011-06-23 | 2013-07-24 | 迪弗斯科技股份有限公司 | Electrostatic induced water unfreezing method and device for food |
-
2012
- 2012-02-08 FI FI20125139A patent/FI123851B/en not_active IP Right Cessation
-
2013
- 2013-02-06 WO PCT/FI2013/050128 patent/WO2013117814A1/en active Application Filing
- 2013-02-06 BR BR112014019547A patent/BR112014019547A8/en not_active Application Discontinuation
- 2013-02-06 CN CN201380008350.6A patent/CN104160067B/en not_active Expired - Fee Related
- 2013-02-06 EA EA201491193A patent/EA028294B1/en not_active IP Right Cessation
- 2013-02-06 CA CA2860814A patent/CA2860814C/en not_active Expired - Fee Related
-
2014
- 2014-08-20 ZA ZA2014/06117A patent/ZA201406117B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| FI20125139A (en) | 2013-08-09 |
| BR112014019547A8 (en) | 2017-07-11 |
| CN104160067B (en) | 2017-06-16 |
| CA2860814C (en) | 2016-07-05 |
| WO2013117814A1 (en) | 2013-08-15 |
| BR112014019547A2 (en) | 2017-06-20 |
| EA028294B1 (en) | 2017-10-31 |
| ZA201406117B (en) | 2016-01-27 |
| FI123851B (en) | 2013-11-15 |
| EA201491193A1 (en) | 2015-04-30 |
| CN104160067A (en) | 2014-11-19 |
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