Aluminum Company of America

Gene S Miller

Robert L Kozarek

Lester L Knapp

Dennis R Raines

Christopher M Seaman

William D McGraw

William M Hall

Joseph C Preston

Kevin G Christian

A transport duct for carrying abrasive materials, such as ceramic powders. The duct comprises an outer casing and an axially extending array of alternating ceramic and polymer segments each having an interior wall defining a passageway. The transport duct is useful for transporting streams of alumina powder to an aluminum electrolysis cell and for other uses where abrasion resistance and avoidance of internal material buildup are important.

Transport duct for abrasive materials

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

Methods of switching electrical current in the operation of an electrical load device such as an electrolytic cell having at least one anode and one cathode. At least one source of electrical current is connected to the anode and cathode at two spaced apart locations thereon. One method comprises the steps of disconnecting one of the locations on the anode and on the cathode from the source of electrical current, and connecting the disconnected locations of the anode and cathode directly together so that the path of current flow to and from the source of electrical current is limited to the anode and cathode. To reconnect the anode and cathode to the source of electrical current, the directly connected locations of the anode and cathode are unconnected from each other and reconnected to the source of electrical current. In addition, the invention includes the use of an anode or cathode, exclusive of the other, as means to heat an electrolytic cell.

Method of operating an electrolytic cell

Growing community of inventors

Maryville, TN, United States of America

Gene S Miller