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The breaching of containment of conventionally deposited mine tailings impoundments, and the consequent release of tailings flows with long run-outs, unfortunately remains not uncommon and often has devastating ecological and economic consequences, occasionally including the loss of human life. Rather than the breaching of containment itself, which can result from a number of causes (poor control of the phreatic surface, unrecognized dam foundation issues), the contributing factor to the severe consequences of dam breach is the low density and strength and (or) susceptibility of the tailings to liquefy or soften under loading, combined with the driving weight of the ponded water, which allows for significant run-outs (in some cases tens of kilometres) to occur. Hence the motivation for developing alternative technologies that dewater tailings before deposition to the point where reliance on containment is minimized or eliminated. In this paper, these technologies are referred to as 'high-density' tailings, which includes any technology that at least produces nonsegregating tailings that will form a sloped stack when deposited, including thickened, paste, and filtered tailings. The paper explores a number of issues related to high-density tailings, including shear behaviour, dewatering behaviour, acid generation, and surface deposition rheology. The paper concludes with some discussion on what the limitations are on this technology that are holding back its wider adoption, and how these limitations might be overcome. [ABSTRACT FROM AUTHOR]

Canadian hard rock mines continue to reach deeper deposits, which poses greater challenges to mine safety including rock burst control. Destress blasting techniques have been successfully employed in such underground mines with the aim of preconditioning highly stressed rock mass to mitigate the risk for rock burst occurrence in deep mines. In the present study, the efficiency of destress blasting is examined through a comparison between traditional and alternative numerical modelling approaches. The traditional modelling approach assumes a uniformly distributed blast-induced damage zone extending over the entire drift face, whilst the alternative modelling approach, presented herein, simulates the damage zone for each individual blast hole. In the first part of this paper, a three-dimensional numerical model of a single blast hole is constructed, whereby the extent of blast-induced damage zone is delineated. The latter part of this paper uses the single-hole model results to examine the efficiency of destress blasting as practiced in drift development in deep mines. It is demonstrated through comparison of FLAC3D numerical simulation results that the traditional modelling approach may lead to an overly optimistic indication of destress blasting efficiency when compared with the alternative modelling approach, in which a more precise simulation of the damage zones is applied. [ABSTRACT FROM AUTHOR]

Large-magnitude mining-induced seismic events can occur as a result of local rock mass stress increase. High apparent stress events can be used as a proxy to identify increases in local rock mass stress conditions. This paper proposes a relative apparent stress ratio (ASR) for quantifying apparent stress of a seismic population. Variations in ASR are analysed over time with reference to seismic hazard inferred from the magnitude of seismic events. The proposed ratio is examined through examples of seismic populations from a single deep Canadian mine. [ABSTRACT FROM AUTHOR]

This Special volume published by the Canadian Journal of Earth Sciences consists of a collection of six papers on the petrology, geochemistry, and metallogeny of igneous rocks emplaced in large igneous provinces (LIPs). The papers provide a snapshot of results presented at a Special Session of the 2017 Geological Association of Canada – Mineral Association of Canada Joint Annual Meeting held in Kingston, Ontario, by members of the vibrant geoscience community dedicated to the study of LIPs. Participants applauded the idea of a joint session on these topics and as a result, the session fostered animated discussions and new collaborations. The scope of magmatic and metallogenic studies of LIPs often precludes the type of brainstorming that took place during the meeting. This Special volume demonstrates that a robust understanding of magmatic processes represents the essential first step towards the search for mineral deposits in LIPs worldwide. [ABSTRACT FROM AUTHOR]

Canadian society faces a significant decline in the number of active mines and in the discovery rate of base and precious metal deposits. Exploring in the shadows of active and former mines with improved metallogenic models and new technologies is one way to address this problem. Another way is to diversify mineral exploration outside known mining camps and target prospective but underexplored settings and nonconventional mineral deposits. In Canadian terms, diversifying exploration commonly translates into targeting gneissic and granitic terrains where modern geoscience knowledge may be rare or only at reconnaissance scale and where key regional and local indicators and vectors to ore may be missing in the geological record. Though underexplored settings abound in Canada, only one orogen has an aura that discourages exploration: the Grenville Province. Consequently, even though the Grenville Province provides the best model of a deep continental-collision zone so far studied anywhere on Earth and constitutes a microcosm of continental accretion, it remains underexplored, underprospected, undermapped and underestimated. It is thus essential to revisit the mineral potential of the most accessible orogen of the Canadian Shield, search for its missing volcanic belts, reexamine its ore deposits and mineral occurrences, and explore new research avenues using the best remote-sensing device on Earth: human eyes. This special issue captures advances associated with regional field investigations by government that played a special role in opening up frontier areas for mineral exploration. Papers stemming from academia and government–university–industry consortiums investigate further some of the topics covered by these and earlier surveys and others contribute structural and metamorphic insights that will be valuable in future mapping projects. The advances reported here for the Grenville Province may provide impetus to revisit other Grenville-age terrains worldwide, just as metallogenic models developed in other countries have provided the means to look in a different manner at the Grenville orogen for mineral deposits. Collectively all the various approaches presented in this volume help us to revamp our way of looking at the mineral potential of the Grenville orogen. [ABSTRACT FROM AUTHOR]