WO2000053826A1 - Electrolytic production of magnesium - Google Patents
Electrolytic production of magnesium Download PDFInfo
- Publication number
- WO2000053826A1 WO2000053826A1 PCT/CA2000/000248 CA0000248W WO0053826A1 WO 2000053826 A1 WO2000053826 A1 WO 2000053826A1 CA 0000248 W CA0000248 W CA 0000248W WO 0053826 A1 WO0053826 A1 WO 0053826A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- anode
- cell
- magnesium
- chloride
- hydrogen
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Ceased
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Classifications
-
- 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
- C25C3/04—Electrolytic production, recovery or refining of metals by electrolysis of melts of magnesium
Definitions
- This invention relates to production of magnesium by electrolysis.
- the molten salt electrolyte typically comprises one or more alkali metal or alkaline earth metal chlorides in which the magnesium chloride is dissolved.
- This invention seeks to provide a new electrolytic process for the production of magnesium from magnesium chloride, in which hydrogen chloride is produced as the by-product.
- This invention also seeks to provide a new electrolytic process for the production of magnesium from magnesium chloride at a lower energy requirement.
- a process for the electrolytic production of magnesium comprising: i) electrolysing magnesium chloride in a molten salt electrolyte in an electrolysis cell having a cathode and an anode, with formation of magnesium metal at said cathode, ii) feeding hydrogen gas to said anode and reacting chloride ions at said anode with the hydrogen gas to form hydrogen chloride, iii) recovering the magnesium metal from said cell, and iv) recovering the hydrogen chloride from said cell.
- an electrolytic cell for production of magnesium metal from magnesium chloride comprising: a) a cell for housing magnesium chloride in a molten salt electrolyte, said cell having a cathode and an anode, b) means for feeding hydrogen gas to said anode, c) means for recovery from said cell of magnesium metal developed at said cathode, and d) means for recovery from said cell of hydrogen chloride developed at said anode.
- the anode is a high surface area anode, for example, a porous anode in which case the hydrogen gas permeates the pores of the anode, such as by diffusion, or molten electrolyte containing the magnesium chloride permeates the pores of the anode, to provide the contact between the hydrogen gas and the chloride ions.
- the hydrogen gas may be fed along a non-porous tube or conduit to the porous anode. If this tube or conduit is in contact with the bath it should not be of a material which will function as an anode for the electrolysis.
- any anode having a structure permitting delivery of hydrogen to the cell bath at the anode may be employed, for example, an anode having drilled channels for communication with a source of hydrogen gas.
- the requirement is that the anode structure deliver hydrogen gas to the cell bath at the anode, so that chloride ions at the anode react with the hydrogen gas to form hydrogen chloride, rather than discharging as chlorine gas.
- suitable anodes may be of graphite, silicon carbide or silicon nitride.
- the method has the advantage that this hydrogen chloride gas is produced with minimal, if any, production of chlorine gas.
- E ad ⁇ ab is the minimum voltage required to carry out the process, assuming 100% current efficiency and that the M g Cl 2 and H 2 are fed at room temperature.
- Table I shows the calculated decomposition voltage (1000 K) and adiabatic voltage required to cover the energy requirements of the process without heat losses.
- Table I further shows that the decomposition voltage decreases by 1.04V and that the overall energy requirement decreases by 0.86V. This means that with HCl formation, another 0.18V per mole can be dissipated in the cell without causing overheating. The decrease of 0.86V translates to a reduction of about 25% less electricity consumption for magnesium production. With magnesium cells currently requiring an average of 12.5 MW-hr per tonne, and an average energy cost of 4 cents per KW-hrs, this translates to a savings of about $125 per tonne of magnesium produced in electrical consumption. Another major cost saving comes from the fact that the cell is producing HCl rather than chlorine, requiring no HCl synthesis plant. Chlorine treatment and handling as well as HCl synthesis can provide for further cost savings.
- the hydrogen gas may be considered to form a hydrogen anode in the cell, for discharge of the chloride ions.
- an anode structure is provided which, can be of any suitable material, for example, graphite, silicon carbide or silicon nitride.
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- 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)
- Manufacture And Refinement Of Metals (AREA)
Abstract
Magnesium metal is produced by electrolysis of magnesium chloride employing a high surface area anode, for example, a porous anode to which hydrogen gas is fed. Hydrogen chloride is formed from the chloride ions at the anode, rather than chlorine gas; the process also has the advantage of operating at a lower voltage with a lower energy requirement than the conventional process in which chlorine gas is generated at the anode.
Description
ELECTROLYTIC PRODUCTION OF MAGNESIUM
TECHNICAL FIELD
This invention relates to production of magnesium by electrolysis.
Conventional electrolytic production of magnesium from magnesium chloride dissolved in a molten salt electrolyte in an electrolytic cell results in formation of magnesium at the cathode and chlorine gas at the cathode. The molten salt electrolyte typically comprises one or more alkali metal or alkaline earth metal chlorides in which the magnesium chloride is dissolved. BACKGROUND ART
The production of chlorine as a by-product of the production of magnesium requires auxiliary equipment for recovery and storage of the byproduct chlorine gas which typically is reacted with hydrogen gas to form hydrochloric acid. Electrolytic methods for producing magnesium are described in U.S. Patents 4,073,703; 4,192,724; 5,089,094 and 5,665,220, the teachings of which are incorporated herein by reference. DISCLOSURE OF THE INVENTION
This invention seeks to provide a new electrolytic process for the production of magnesium from magnesium chloride, in which hydrogen chloride is produced as the by-product.
This invention also seeks to provide a new electrolytic process for the production of magnesium from magnesium chloride at a lower energy requirement.
In accordance with one aspect of the invention there is provided in a process for the electrolytic production of magnesium from magnesium chloride in an electrolytic cell having an anode and a cathode, and in which magnesium is generated at the cathode, the improvement wherein hydrogen gas is fed to the anode and hydrogen chloride is formed in situ at the anode.
In accordance with another aspect of the invention there is provided a process for the electrolytic production of magnesium comprising: i) electrolysing magnesium chloride in a molten salt electrolyte in an electrolysis cell having a cathode and an anode, with formation of magnesium metal at said cathode, ii) feeding hydrogen gas to said anode and reacting chloride ions at said anode with the hydrogen gas to form hydrogen chloride, iii) recovering the magnesium metal from said cell, and iv) recovering the hydrogen chloride from said cell.
In accordance with still another aspect of the invention there is provided an electrolytic cell for production of magnesium metal from magnesium chloride comprising: a) a cell for housing magnesium chloride in a molten salt electrolyte, said cell having a cathode and an anode, b) means for feeding hydrogen gas to said anode, c) means for recovery from said cell of magnesium metal developed at said cathode, and d) means for recovery from said cell of hydrogen chloride developed at said anode.
In accordance with yet another aspect of the invention there is provided use of hydrogen in an electrolytic cell for the production of magnesium from magnesium chloride with production of by-product hydrogen chloride at the anode. DESCRIPTION OF BEST MODES
In particular the anode is a high surface area anode, for example, a porous anode in which case the hydrogen gas permeates the pores of the anode, such as by diffusion, or molten electrolyte containing the magnesium chloride permeates the pores of the anode, to provide the contact between the hydrogen gas and the chloride ions. The hydrogen gas may be fed along a non-porous tube or conduit to the porous anode. If this tube or conduit is in contact with the bath it should not be of a material which will function as an anode for the electrolysis.
As an alternative to a porous anode, any anode having a structure permitting delivery of hydrogen to the cell bath at the anode may be employed, for example, an anode having drilled channels for communication with a source of hydrogen gas. The requirement is that the anode structure deliver hydrogen gas to the cell bath at the anode, so that chloride ions at the anode react with the hydrogen gas to form hydrogen chloride, rather than discharging as chlorine gas.
By way of example, suitable anodes may be of graphite, silicon carbide or silicon nitride.
It has been found that introducing hydrogen at the anode in the electrolytic cell for magnesium metal production results in a lower energy requirement for the cell, and the cell can be operated at a cell voltage lower than the cell voltage of a corresponding cell having a conventional carbon or graphite anode, without hydrogen gas.
In addition it is found that hydrogen chloride is formed directly at the anode by the reaction:
2d" + H2(g) = 2HCl(g) + 2e~
where (g) indicates the gas phase.
Furthermore, the method has the advantage that this hydrogen chloride gas is produced with minimal, if any, production of chlorine gas.
In conventional cells in which chlorine gas is produced as the byproduct, the anode is graphite, and at the high temperatures of operation some chlorinated hydrocarbons are produced by reaction between the chlorine gas and the carbon anode, and this presents environmental problems. Eliminating production of chlorine gas in the present invention can be expected to alleviate these problems.
Table I below shows how the decomposition voltage of the electrolysis decreases, with the process of the invention, as compared with the conventional process and how the minimum voltage required to maintain energy balance changes.
TABLE I
In Table I, Eadιab is the minimum voltage required to carry out the process, assuming 100% current efficiency and that the MgCl2 and H2 are fed at room temperature.
In particular, Table I shows the calculated decomposition voltage (1000 K) and adiabatic voltage required to cover the energy requirements of the process without heat losses.
Table I further shows that the decomposition voltage decreases by 1.04V and that the overall energy requirement decreases by 0.86V. This means that with HCl formation, another 0.18V per mole can be dissipated in the cell without causing overheating. The decrease of 0.86V translates to a reduction of about 25% less electricity consumption for magnesium production. With magnesium cells currently requiring an average of 12.5 MW-hr per tonne, and an average energy cost of 4 cents per KW-hrs, this translates to a savings of about $125 per tonne of magnesium produced in electrical consumption.
Another major cost saving comes from the fact that the cell is producing HCl rather than chlorine, requiring no HCl synthesis plant. Chlorine treatment and handling as well as HCl synthesis can provide for further cost savings.
Environmetal problems associated with chlorine gas production are expected to be alleviated.
The hydrogen gas may be considered to form a hydrogen anode in the cell, for discharge of the chloride ions. In such case an anode structure is provided which, can be of any suitable material, for example, graphite, silicon carbide or silicon nitride.
Claims
1. In a process for the electrolytic production of magnesium from magnesium chloride in an electrolytic cell having an anode and a cathode, and in which magnesium is generated at the cathode, the improvement wherein hydrogen gas is fed to the anode and hydrogen chloride is formed in situ at the anode.
2. A process according to claim 1, wherein the anode is a high surface area anode.
3. A process according to claim 1, wherein the anode is a porous anode and the hydrogen gas permeates the pores of the anode.
4. A process according to claim 1, wherein said magnesium chloride is dissolved in a molten salt electrolyte in said cell, said anode is a porous anode and the molten electrolyte permeates the pores of the porous anode.
5. A process according to claim 1, 2, 3 or 4, wherein the anode is of graphite, silicon carbide or silicon nitride.
6. A process, according to claim 1, for the electrolytic production of magnesium comprising: i) electrolysing magnesium chloride in a molten salt electrolyte in an electrolysis cell having a cathode and an anode, with formation of magnesium metal at said cathode, ii) feeding hydrogen gas to said anode and reacting chloride ions at said anode with the hydrogen gas to form hydrogen chloride, iii) recovering the magnesium metal from said cell, and iv) recovering the hydrogen chloride from said cell.
7. A process according to claim 6, wherein said cell is operated at a cell voltage lower than the cell voltage of a corresponding cell having a carbon anode, without hydrogen gas, in which chlorine gas is developed at the anode.
8. A process according to claim 6 or 7, wherein said anode is a high surface area anode.
9. A process according to claim 6 or 7, wherein said anode is a porous anode and the hydrogen gas permeates from the pores of the anode into the cell.
10. A process according to claim 6 or 7, wherein said anode is a porous anode and the molten electrolyte permeates the pores of the porous anode.
11. A process according to claim 6, 7, 8, 9 or 10, wherein said anode is of graphite, silicon carbide or silicon nitride
12. An electrolytic cell for production of magnesium metal from magnesium chloride comprising: a) a cell for housing magnesium chloride in a molten salt electrolyte, said cell having a cathode and an anode, b) means for feeding hydrogen gas to said anode, c) means for recovery from said cell of magnesium metal developed at said cathode, and d) means for recovery from said cell of hydrogen chloride developed at said anode.
13. A cell according to claim 12, further including a conduit for delivery of hydrogen gas to said anode.
14. A cell according to claim 12 or 13, wherein said anode is a high surface area anode.
15 A cell according to claim 12 or 13, wherein said anode is a porous anode.
16. A cell according to claim 12, 13, 14 or 15, wherein said anode is of graphite, silicon carbide or silicon nitride
17. Use of hydrogen in an electrolytic cell for the production of magnesium from magnesium chloride with production of by-product hydrogen chloride at the anode.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU31390/00A AU3139000A (en) | 1999-03-11 | 2000-03-09 | Electrolytic production of magnesium |
| US09/933,802 US20020014416A1 (en) | 1999-03-11 | 2001-08-22 | Electrolytic production of magnesium |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2,265,183 | 1999-03-11 | ||
| CA002265183A CA2265183C (en) | 1999-03-11 | 1999-03-11 | Magnesium metal production |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US09/933,802 Continuation US20020014416A1 (en) | 1999-03-11 | 2001-08-22 | Electrolytic production of magnesium |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2000053826A1 true WO2000053826A1 (en) | 2000-09-14 |
Family
ID=4163374
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/CA2000/000248 Ceased WO2000053826A1 (en) | 1999-03-11 | 2000-03-09 | Electrolytic production of magnesium |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US20020014416A1 (en) |
| AU (1) | AU3139000A (en) |
| CA (1) | CA2265183C (en) |
| WO (1) | WO2000053826A1 (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8608935B2 (en) * | 2006-03-24 | 2013-12-17 | GM Global Technology Operations LLC | Apparatus and method for synthesis of alane |
| CA2829049C (en) | 2011-03-18 | 2014-12-02 | Orbite Aluminae Inc. | Processes for recovering rare earth elements from aluminum-bearing materials |
| WO2012149642A1 (en) | 2011-05-04 | 2012-11-08 | Orbite Aluminae Inc. | Processes for recovering rare earth elements from various ores |
| IN2014DN03007A (en) | 2011-09-16 | 2015-05-08 | Orbite Aluminae Inc | |
| WO2013104059A1 (en) | 2012-01-10 | 2013-07-18 | Orbite Aluminae Inc. | Processes for treating red mud |
| CN102534688B (en) * | 2012-01-10 | 2014-12-10 | 华东理工大学 | High-current baffleless magnesium electrolytic tank |
| EP2838848B1 (en) | 2012-03-29 | 2019-05-08 | Orbite Technologies Inc. | Processes for treating fly ashes |
| WO2014029031A1 (en) * | 2012-08-24 | 2014-02-27 | Alliance Magnésium | Process for treating magnesium-bearing ores |
| US9353425B2 (en) | 2012-09-26 | 2016-05-31 | Orbite Technologies Inc. | Processes for preparing alumina and magnesium chloride by HCl leaching of various materials |
| BR112015011049A2 (en) | 2012-11-14 | 2017-07-11 | Orbite Aluminae Inc | Methods for Purification of Aluminum Ions |
| JP6465816B2 (en) * | 2013-02-14 | 2019-02-06 | アライアンス・マグネシウム | HYDROGEN GAS DIFFUSION ANODE ASSEMBLY DEVICE FOR GENERATING HCl AND ELECTROLYTIC CELL INCLUDING THE ASSEMBLY DEVICE |
| CA2950004A1 (en) * | 2014-05-26 | 2015-12-03 | Procede Ethanol Vert Technologie | Process for pure aluminum production from aluminum-bearing materials |
| US10423746B2 (en) * | 2015-07-23 | 2019-09-24 | Texas Instruments Incorporated | Compensation design of power converters |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5665220A (en) * | 1995-12-26 | 1997-09-09 | General Motors Corporation | Electrolytic magnesium production process |
-
1999
- 1999-03-11 CA CA002265183A patent/CA2265183C/en not_active Expired - Fee Related
-
2000
- 2000-03-09 WO PCT/CA2000/000248 patent/WO2000053826A1/en not_active Ceased
- 2000-03-09 AU AU31390/00A patent/AU3139000A/en not_active Abandoned
-
2001
- 2001-08-22 US US09/933,802 patent/US20020014416A1/en not_active Abandoned
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5665220A (en) * | 1995-12-26 | 1997-09-09 | General Motors Corporation | Electrolytic magnesium production process |
Non-Patent Citations (2)
| Title |
|---|
| CHEMICAL ABSTRACTS, vol. 129, no. 18, 2 November 1998, Columbus, Ohio, US; abstract no. 236807, TAKENAKA, T. ET AL: "Electrode behavior of hydrogen in alkali halide melts" XP002141418 * |
| MOLTEN SALT FORUM (1998), 5-6(MOLTEN SALT CHEMISTRY AND TECHNOLOGY 5), 275-278, 1998 * |
Also Published As
| Publication number | Publication date |
|---|---|
| AU3139000A (en) | 2000-09-28 |
| CA2265183A1 (en) | 2000-09-11 |
| CA2265183C (en) | 2008-01-08 |
| US20020014416A1 (en) | 2002-02-07 |
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