Kaiser said it settled a number of antitrust cases.

Subject to approval by the U.S. District Court in Philadelphia, Kaiser Aluminum will pay $3 million to settle claims of buyers--from June 3, 1971, through Dec. 30, 1980--of Kaiser’s residential, commercial and farm aluminum roofing, siding and related building products. The litigation has been pending since 1975. A spokesman for the Oakland-based firm said the company has consistently denied liability in these cases. However, in view of continuing litigation costs, the uncertainty of trying cases of this complexity before a jury and the amount of the claims involved, the company agreed to join other defendants in a settlement.