1994 Fiscal Year Final Research Report Summary
Energy Efficient Production of High-Purity Aluminum by Using an Aluminum Scrap-Chlorine Fuel Cell as One of the Component Processes.
| Project/Area Number |
04453056
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
金属精錬・金属化学
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| Research Institution | Hokkaido University |
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Principal Investigator |
ISHIKAWA Tatuo Hokkaido University, Facaulty of Engineering, Professor, 工学部, 教授 (10001158)
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| Project Period (FY) |
1992 – 1994
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| Keywords | Aluminum-Chlorine Fuel Cell / aluminum Chloride / Electrochemical Cycle / Aluminum Scrap / Molten Salt System / Graphite Cathode / Reaction Resistance / Reaction Zone Length |
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| Research Abstract |
An aluminum-chlorine fuel cell for manufacturing aluminum chloride was proposed as one component process of an electrochemical cycle for reproduction of hig-purity aluminum from aluminum scrap. Using this fuel cell, much electric energy can be produced in contrast to the usual direct chlorination of aluminum, and by applying this energy to the electrowinning process, a very advantageous electrochemical cycle for high-purity aluminum production can be constructed in a molten salt system.
To develop the cathode for the fuel cell, three types of graphite electrodes referred to as the drilled type, grooved type and slit type were tested by changing reaction zone lengths. The perfomance for the reduction reaction of chlorine was investigated in terms of the discharge characteristics of the cell in a mixture of MgCl_2 25mol%-NaCl 75mol% at 750^oC.
We obtained the following results from experimental tests. The discharge characteristics showed that the voltage droped due to the resistance of the reduction reaction which decreased with the increase in the length of the reaction zone. The grooved electrodes and slit electrodes gave better efficiencies than those of the drilled electrodes, because both these electrodes enlarged the length of the reaction zone more than drilled ones. Stirring the melts near the reaction zone caused the discharge characteristics of the cell to decline. It was also found that the product of the reaction resistance and reaction zone length was nearly constant. This relationship gives us a guiding principle for design of a new fuel cell.
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