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Ultra-class mining trucks used for material haulage in rugged surface mining terrains experience premature tire fatigue failure in operation. Typical failures include belt edge separation, ply turn-up separation, and tread base and sidewall cracking. The use of reinforcing fillers and processing aids in tire compounds result in the formation of microstructural in-homogeneities in the compounds. This article presents an application of the critical plane analysis technique for predicting the fatigue life of the belt package of an ultra-large mining truck (CAT 795F) tire of size 56/80R63 in a surface coal mine. Experimental data obtained from extracted specimens (sidewall, tread, and belt edge region) of the tire are used to characterize the stress-strain and fatigue behavior of the modeled tire. The tire's duty cycle stresses and strains were obtained from finite element analysis of the rolling tire in Abaqus. Fatigue life calculations were performed in the rubber fatigue solver Endurica CL. Effects of inflation pressure, tire speed, and axle load on the fatigue life of the belt package under strain-crystallizing and non-crystallizing conditions of the belt compound are discussed. Specifically, the results show the belt edges to be critical regarding crack nucleation.

This work presents a new method of mine ventilation network optimisation as standard non-linear programming problem and discusses the use of a novel firstorder Lagrangian (FOL) algorithm for equality constraints as a solution tool for these problems. Slack variables have been defined to transform such inequality constraints into their corresponding equality forms. The problem is then converted to non-linear problem with equality constrains. The methodology adopted in this paper is capable of dealing with the non-linear convex model with significant savings on computational efforts due to its use of only first derivatives. A MATLAB programme has been developed based on the FOL method to solve a generalised mine ventilation network optimisation problem. To study the validity and the viability of the FOL programme, the programme has been applied to already published network problems and both results are identical.

The need to increase productivity has led to innovations in highly mechanized equipment such as the continuous miner (CM). However, often times the CM is underutilized, resulting in loss of productivity and increased operating cost. The objective of this study is to apply a simulation tool to evaluate if optimizing support systems, such as cut-out distance, fleet size, and panel dimensions, can maximize CM utilization and productivity. Discrete event simulation is used to analyze different cut-out distances for a room and pillar mining system. The results show that an 11-entry panel width with a fleet size of three shuttle cars is optimum for the variable cut-out distances examined. The utilization and production rate also increases by 6% at the maximum cut-out distance.

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