Power requirements for grinding is often calculated using experimen- tal data from prior operations as the work index for materials and ores are often unknown. In grinding a feed materials for which 80% passes through a 4-mesh screen, the power requirement was 5.9kW to produce a product 80% of which passes through a 48-mesh screen. What will be required power to produce a finer product 80% of which passes through a 200-mesh screen? I