Cleveland Cliff Iron Co. said yesterday it plans to lay off more than 2,300 workers at the Tilden and Empire mines in Michigan next month because of continued low production in the American and Canadian steel industries.

U.S. Steel, reacting to slumping orders from the oil drilling market, has planned Easter weekend layoffs of 6,600 workers at the company's National and Duquesne plants in McKeesport, Pa. The layoffs will extend through the week of April 18.

U.S. Steel's layoffs now stand at 11,300 in its Pittsburgh district.

Bethlehem Steel Corp. said it will furlough an additional 2,100 steelworkers at its Sparrows Point steel mill outside Baltimore, effective Sunday, bringing total layoffs at the plant to 5,900. The company said it would reassess the markets next week to determine if any workers can be reinstated.

Republic Steel Corp. announced yesterday that it would permanently close its plant in Youngstown, Ohio, idling 450 persons. A spokesman said the plant was losing too much money to stay in operation.

Armco Inc. has furloughed another 180 workers at its Butler plant because of a slump in orders, bringing the layoff total to 480. The plant, which produces tubular goods for the oil and gas industry, employs about 3,000 steelworkers.