3 A cement grinding mill A with a capacity of 50 tons per
the secretary works 2, 400 hours a year and the executive 3, 000 hours a year. 3. A cement grinding mill A with a capacity of 50 tons per hours utilizes forged steel grinding balls costing P12, 000 per ton, which have a wear rate of 100 grams per ton cement milled. Another cement mill B if the same capacity uses high chrome steel grinding bans costing P30, 000 per ton with wear