Rock Fracturing Mine to Mill Optimization

摘要

The research presented in this dissertation consists of four topics. The first of these topics is an experimental study of rock fracturing due to rapid thermal cooling, and the other three topics are related to mine-to-optimization. This includes the development and testing of a site-specific model for blast fragmentation, the development of a technique for utilizing digital image processing and ground-based LIDAR for rock mass characterization, and an experimental study of the effects of ore blending on mineral recovery. All four topics are related through the subject of rock fracturing and rock fragmentation. The results from this research are important and can be used to improve engineering design associated with rock excavation and rock fragmentation. First of all, a successful set of laboratory experiments and 3D numerical modeling was conducted, looking at the effects of rapid thermal cooling on rock mechanical properties. The results gave the unexpected finding that depending on the rock type and the thermal conditions, rapid cooling can result in either overall crack growth or crack closing. Secondly, a site-specific model for predicting blast fragmentation was developed and tested at an open-pit copper mine in Arizona. The results provide a practical technique for developing a calibrated blasting model using digital images and digital image processing software to estimate in-situ block size, and a calibrated Schmidt hammer to estimate intact tensile strength. Thirdly, a new technique was developed to conduct cell mapping in open-pit mines using the new technologies of digital image processing and ground-based LIDAR. The results show that the use of these new technologies provide an increased accuracy and the ability for more sophisticated slope stability analyses with no increase in field time only a moderate increase in data processing time. Finally, a successful set of laboratory experiments was conducted looking at the effects of ore blending and grinding times on mineral recovery from a set of six ore from a copper mine in Arizona. The results gave the unexpected finding that for a fixed grinding time, the mineral recovery of the blended ores exceeded the average of the individual recoveries of the same ores unblended.