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The New Mine Level Project is a 130 000 tonnes per day (tpd) panel caving project set to start in 2017. The high stresses, complex structural setting and high mining rates present major challenges in terms of seismicity management and rockburst hazard reduction. This paper is a case study of the calculation of the energy requirements needed to design a dynamic support system for this operation. This analysis starts with the estimation of the seismic source, forecast through the use of numerical modelling and verified with observed past data; later peak particle velocity (PPV) is calculated at the drifts using a PPV attenuation model and an amplification factor is used near the excavations. The amount of fractured rock around the drifts that could be ejected by a seismic event is calculated through numerical modelling. With the ejection velocity estimated from PPVs, energy demand is obtained. All the values resulting from numerical analysis were compared to historical data of similar mine sectors. As the results show that the methodology used in this paper agrees well with previously observed rockburst episodes, it was used to calculate the yielding support of this new deep mine project. [ABSTRACT FROM AUTHOR]

This paper presents the results of a series of recent studies to investigate the improved optimal design and planning of the main ventilation systems of complex multi-level mine networks using a genetic algorithm (GA) routine. It is concluded that the method may be successfully used to investigate the benefits offered by alternative ventilation configurations and to determine the most practical and cost-effective ventilation system during the various mine planning stages (short-, medium- and long-term). In particular, the optimum number, location and duties of booster fans, and size and location of regulators may be evaluated and selected. The objective of the final ventilation design is to identify the ventilation system that operates in both a safe and energy-efficient manner. The method has been refined to include the selection of practical fan units that match the optimal fan operating duties determined by the GA routine. The paper also reviews general optimisation strategies that may be employed to enhance and maintain the performance of mine ventilation systems. [ABSTRACT FROM AUTHOR]

This paper presents the results of controlled blasting experiments and blast modelling carried out to understand and quantify the effect of blasting on the creation of fractures inside fragments referred to as conditioning. Fragment conditioning is studied through the use of indirect and direct measurement techniques on samples collected from different zones around an explosive charge. Modelling is used to map different levels of conditioning throughout the blasted samples and explore the impact of boundary conditions on the spatial distribution of conditioning levels. Combined statistical analysis of repeatable tests showed that the measured impact breakage ranking parameter (A*b) increased by 20 and 33% within the low and intermediate conditioning zones respectively. This translates into a statistically significant strength reduction of the material. These results in conjunction with other documented experience suggest that blast-induced conditioning can have a positive impact on comminution performance and thus energy consumption. Results from this work provide the basis for a methodology to better define postblast breakage strength inputs into comminution performance models; as well as a preliminary approach to scale up the extent and degree of conditioning by blasting. Further work is required to evaluate the ability to control the degree of conditioning through the application of improvements in designs and novel blasting technology [ABSTRACT FROM AUTHOR]

As open out mines become progressively deeper, mining operations face increased operating costs and technical challenges. In-Pit Crusher Conveyor (IPCC) systems offer advantages in the form of continuous operation, reduced labour requirements and decreased energy consumption resulting in lower cost per bank cubic metre. Nevertheless, IPCC systems are associated with high capital costs, lack of flexibility to adapt to changing mine plans and low effective system utilisation. This paper investigates alternative IPCC configurations for pre-stripping application in an open pit coal mine. It demonstrates that system redundancy in the form of introducing parallel conveyor lines with spreaders is capable of improving IPCC productivity by 9-4-12-6%. Parallel conveying systems have higher Equivalent Unit Costs (EUCs) than do single conveyor IPCC configurations. Nevertheless, introducing redundancy into IPCC systems enables higher production and associated coal revenue. Using an indicative metallurgical coal price and stripping ratio, it was demonstrated that parallel conveyor IPCC systems can provide higher profit than single conveyor line IPCC alternatives. [ABSTRACT FROM AUTHOR]

The intrinsic specific energy, that is the minimum energy consumed by pure cutting action to cut unit volume of rock, along with the rock strain energy, that is the absorbed energy by unit volume of rock in uniaxial compression, were used together to assess rock cutting performance. A series of rock cutting tests using a single polycrystalline diamond compact (PDC) cutter under steady conditions, and uniaxial compressive tests with a single-cyclic loading, otherwise monotonic loading were carried out on rock samples. Different rock types having unconfined compressive strength values of 9–249 MPa were carefully tested to determine the intrinsic specific energy and strain energy values. The results suggest that stress and strain characteristics of the rock obtained from uniaxial compressive tests, in terms of absorbed energy, can be related to cutting performance. Therefore, it was concluded that the strain energy can be used to assess the intrinsic specific energy to evaluate drilling performance in PDC cutting. [ABSTRACT FROM PUBLISHER]

Research has recognised operators' skill as important factors affecting performance and energy efficiency of mining equipment. Modern monitoring tools generate large, highly variable, and, often, skewed energy efficiency data sets. Well-conceived statistical tests should be used to assess the effect of operators on energy efficiency in such situations. However, in many cases in the mining literature, the choice of statistical tests to evaluate operator effects has not been systematic and rigorous and, often, the underlying assumptions of these tests have not been examined before their use. This work provides a systematic method, synthesised from the statistical literature, to rigorously evaluate the effect of operators on energy efficiency of mining equipment. Mine engineers and managers can use this method to evaluate whether differences exist in energy efficiency of their operators given sample data and focus on operator training, if they find cause to improve operator performance. [ABSTRACT FROM AUTHOR]