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The Inert Electrodes Program, conducted by Pacific Northwest Laboratory (PNL), involves improving the Hall-Heroult Cells used by the aluminum industry for the electrochemical production of aluminum. The PNL research centers on developing more energy-efficient, longer-lasting anodes, cathodes, and ancillary equipment. During the FY 1989 and FY 1990, preparations for the pilot cell test continued. Numerous unanticipated problems were encountered that delayed the test schedule. The delays resulted primarily from three factors: (1) modifications for anode design based on the results obtained from the prototype test (documented here); (2) difficulties in procuring a manufacturer for the cermet inert anodes to be used in the pilot cell; and (3) problems in the actual scale-up activities, both in the production of the ferrite powder and in the fabrication of the anodes themselves. Issues related to scaling up the fabrication of the anodes are still being addressed in FY 1991. Important accomplishments in FY 1989 and FY 1990 include the completion of laboratory cell tests in which the effects of current density, pre-corrosion, and silica content on anode performance were confirmed; the performance of tests that resulted in the identification of the reaction layer on cermet anodes; the initiation of electrochemical tests to determinemore » the source of the anode impedance; the completion of studies to identify and summarize optimal fabrication conditions for the cermet inert anodes, including advanced compositions; the testing of anodes with advanced composition; the refinement of the electrical connection for the anode; and modeling the dynamics of the anode array to be used in the pilot cell. 15 refs., 23 figs.« less |
