Northwest Aluminum Company

James H Nordquist

Improved methods and apparatus for carrying out the methods are disclosed for feeding alumina into a Soderberg type aluminum reduction cell (10), so as to maximize efficiency of the cell. The apparatus includes a continuous point feeder assembly (12) connected to the cell structure over an exposed peripheral portion of the cryolite bath. The feeder assembly includes as alumina feed hopper (40) and a pair of vertically disposed feeding bins (56). Each feeding bin receives alumina from the hopper. A piston and cylinder assembly (46) is connected to the feeder assembly and arranged to drive a crust breaking member (44) down through bath crust (17) to form a temporary opening. The crust breaking member includes discharge port covers (62) which cover the lower ends of the feeding bins when the crust breaking member is retracted, and uncover the lower ends when the crust breaking member is extended, thereby opening feed discharge ports (60) and allowing a predetermined quantity of alumina to flow through the opening and into the bath. The point feeder assembly is actuated at predetermined, frequent intervals and the hopper refilled as necessary. Occasionally, the peripheral curst is broken by an elongate horizontal breaker bar (34) and a supplemental charge of alumina is forced into the bath to achieve maximum concentration.

Growing community of inventors

The Dalles, OR, United States of America

James H Nordquist