Grinding Mill Power Consumption

Abstract

Equations and associated procedures for estimating power draw are inconsistent. The various methods are discussed critically. Topics discussed are: diameter exponent; loading; speed correction factors; buoyancy effects; liner wear, and effect of load dilation. Balance between effective load weight and torque-arm length determines direction of power change at critical operating points (e.g. incipient overloading). Consistent procedures for calculating the effect of charge weight on power draw in different mill types are given. Error analysis shows that the accuracy of power estimation and data correlation may depend as much on the accuracy of measurement of mill dimensions and operating variables as on the particular equation used. An equation based on the torque-arm model, and providing a compromise between existing equations, is proposed. It is simple and suitable for correlating data and estimating power draw. A data-base of power related parameters documenting mill scale-up during the past few decades is needed. A format for full reporting of essential data is suggested.