This paper presents an approach to decide a cost effective replacement intervals for the liners of a grinding mill used in ore processing plants. The replacement model is based on the detailed analysis of mill performance characteristics, mill failure statistics and maintenance of mill liner. The model formulation for optimum replacement and mill efficiency includes the cost and revenue drivers for the mill. The developed decision model incorporates maintenance cost and monetary gain by doing analysis of production performance of the mill.The developed mathematical model uses the various types of process data i.e. power consumption, mill load, feed flow, metal recovery etc. which is analyzed to establish correlation with life cycle of mill liners. Due to lack of process data for some particular ore types, various techniques such as smoothing, interpolation, simulation and distribution analysis are used to generate the data for the periods for which data is not available. The paper also discusses practical problems encountered while modeling of the real data using classical approach for replacement decisions. The main objective of this paper is to develop a decision support model for taking a cost effective optimum replacement interval for mill liners. A case study was carried out on real data obtained from an ore dressing plant to validate the model.