Aluminum Company of America

Christopher M Seaman

Donald J Spinella

Charles B Wolf

Edward P Patrick

Robert L Kozarek

A Victor Pajerski

Gene S Miller

Philip J Blakeley

William M Hall

Kevin G Christian

William D McGraw

Regis J Huth, Jr

A method and apparatus for graining a surface having a substantial area traveling at a substantial rate of speed. The method includes directing the surface past an array of electrical arcs traveling about a plurality of loop electrodes arranged to provide overlapping arc loop paths as the surface travels past the array of arc loops. The arc loops are established between the loop electrodes and the traveling surface, and thus contact the surface to grain the same. When each arc is struck between its loop electrodes and traveling surface, it is magnetically impelled about the loop of its electrode by a magnetic field established perpendicular of the direction of arc current flow. An annular sheath of gas is provided on each side of the electrode loop and the arc struck between the electrode loop and the traveling surface.

Arc treatment of metal surfaces

A method of estimating and controlling the concentration of alumina in the bath of a Hall cell. The method includes the use of an estimator that employs two sets of equations, namely, a time update algorithm that contains a dynamic model of the alumina mass balance of the cell and provides estimates of alumina concentration, and a measurement algorithm that uses a process feedback variable from the cell to modify the alumina estimate. In addition, the method includes the use of one or more tuning parameters, such as state noise variance and measurement noise variance. The measurement noise variance is modified by the process noise variance in a manner that increases measurement noise variance for high values of process noise and decreases measurement noise variance for low values of process noise. In addition, one or more of the parameters of the model are modified by the feed history of the cell.

Estimation and control of alumina concentration in hall cells

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Jeannette, PA, United States of America

Christopher M Seaman