Coal Mine Productivity Assessment As Influenced By Equipment Reliability And Availability.

Feasible methods, measures and models which can be used to assess the availability of a continuous mine system are developed. The models, based on a simplified representation of room-and-pillar mining, are derived using the principles of Markov processes. A new measure of system reliability and performance, called the penalized availability is defined. This measure can be applied to any process flow system whose output may be derated due to failures of certain components. Three reliability indices which measure coal productivity in terms of equipment reliability and maintainability are defined. These indices are linearly related to the penalized availability by such constant coefficients like annual working shifts, production rate and cost of downtime. Moreover, a procedure for a sensitivity analysis of the models has been described. This analysis can be used to identify the weak link(s) in a system. A graph and a sensitivity equation, which can be used to analyze differences or variations in failure and repair rates are given. The feasibility of the techniques is demonstrated by calculating the indices of a representative coal mine. The failure rates for this mine are estimated from its field maintenance records using appropriate statistical estimation techniques. These same failure data are used to determine a suitable statistical distribution of the lifetime of mine equipment. The repair rates used in the calculations are taken from another study. The aforementioned graph and sensitivity equation are derived using these same failure rates and repair rates