GEORGE EDWARD LYNESS
Engineers in Pittsburgh, PA

5114472, May 19, 1992

Dec 13, 1990

7/627000

C. Edward Eckert - New Kensington PA
Thomas R. Hornack - Lower Burrell PA
George E. Lyness - Pittsburgh PA
John A. Kaems - Maryville TN
Clarence J. Cox - Maryville TN
Ronald E. Miller - Murrysville PA
Diran Apelian - Worcester MA
Rajakkannu Mutharasan - Broomall PA

Aluminum Company of America - Pittsburgh PA

C22B 902

75412

A filter system for removing solid impurities from molten metal is described comprising a housing containing vertically disposed rigid coarse filter facing the incoming flow of molten metal and capable of removing solids having a particle size of at least 10 microns and a rigid fine filter mounted vertically behind the coarse filter and capable of removing solids having a particle size as small as 1 micron. The apparatus further includes a heater for maintaining the temperature of the molten metal and a sparger mounted adjacent the front face of one filter to provide an intermittent gas flow over the face of the filter to dislodge solids on the filter as filter cake. In a preferred embodiment, the rigid filters are nested cylinders, and the molten metal is directed to the center of the smaller coarse filter cylinder from which it then flows through the coarse filter outward to and through the fine filter cylinder and then from the fine filter out of the filter housing.