Key Research Findings in Mining and Environment by the RIME UQAT-Polytechnique

The mining industry is a major driver of the Quebec economy, not only in terms of employment and exports, but also in terms of innovation. However, mining generates waste that is potentially harmful to the environment. The two main types of waste from mining activities are waste rock and tailings. Waste rock is economically unviable material extracted using explosives to reach the ore, while tailings are crushed rock particles resulting from ore processing. Over the past 20 years, the mining industry has invested significantly in developing tools and techniques to properly manage these wastes. Despite this progress, there is still some research work to do in this area, particularly regarding the reclamation of mine waste storage areas that contain reactive minerals that can generate contaminated mine drainage (acidic or neutral). During Phase II of RIME UQAT-Polytechnique, fundamental and practical knowledge related to the reclamation of mine sites was developed. The research also helped train tomorrow’s experts in this field, in order to promote responsible mining development. This presentation will summarize this work and present research perspectives for the coming years.

The exploitation of mineral resources generates large quantities of solid waste, which can impact the environment. The responsible management of solid waste is one of the mining industry's biggest challenges and a priority for governments due to the associated geotechnical (dyke breaches) and geochemical (mine drainage generation) risks. There is a paradigm shift taking place within the mining industry in that solid waste is now being considered as a potential resource. However, in the case of reactive mine tailings that have the potential to generate contaminated mine drainage, a reprocessing step is required to modify their geochemical properties to meet the desired recovery requirements. For many years, researchers at UQAT have been actively developing concrete solutions for reclaiming mine tailings on or off site. This presentation will provide an overview of the research being conducted on mine tailings reclamation in collaboration with mining partners as part of Phase II of the RIME-UQAT-Polytechnique project. These projects fall into two main categories: 1) environmental desulphurization of tailings and waste rock to produce materials for mine reclamation and 2) recovery of critical and strategic minerals in mining and metallurgical tailings. The case studies presented on the recovery of mining and metallurgical tailings provide positive and concrete examples of the integration of circular economy principles into the exploitation of mineral resources in Canada.

Mine waste storage areas expose unstable minerals to weathering, which can contaminate water through mine drainage. Ore extraction can also contaminate water through the effluent produced. Predicting the potential for mine drainage contamination is essential to anticipate management and reclamation methods that will minimize the generation of aqueous contamination. In addition, when contamination occurs despite precautions, water treatment is necessary to minimize environmental impacts. During Phase II of the RIME-UQAT-Polytechnique partnership, several studies focused on different avenues for improving the prediction of mine drainage water quality, as well as the treatment and management of mine water (drainage and ore separation processes). The presentation will provide an overview of this work and the new opportunities in applied research on these themes. In water quality prediction, studies on the influence of temperature on contaminant generation, on the development of new tools for predicting contaminated neutral drainage, as well as on significant advances in numerical modeling of reactive transport applied to prediction will be presented. In the treatment and management of mine water, studies on the performance (efficacy, compliance, residual contamination, sludge recovery) of traditional and innovative processes, passive and active, for conventional contaminants and contaminants of emerging interest will be presented, using a bio-geo-hydrochemical approach.

Technological advances, combined with growing global demand for a variety of natural resources, have led to increased mining activity across the country, particularly in the Canadian Arctic. The development of these projects raises unique engineering and environmental challenges, mainly due to the thermo-hydric conditions specific to permafrost regions and the presence of frost. These factors have a direct impact on the management of mine tailings and approaches to site restoration. The aim of this presentation is to outline recent developments in the management of mine tailings and the restoration of mine sites in arctic conditions carried out at the Research Institute for Mining and the Environment UQAT-Polytechnique. An overview of the main research projects focusing on this theme will be presented, highlighting the key results as well as the practical spin-offs of the work carried out. These spin-offs will improve our ability to design, manage and restore mine tailings disposal areas in Arctic conditions, while providing valuable expertise to the Québec and Canadian mining community.

Mine soils present significant challenges for ecological rehabilitation in forested contexts due to the limited amounts of topsoil available and the high requirements of tree species. Several projects carried out at RIME UQAT-Polytechnique have explored revegetation techniques to overcome these constraints and facilitate the afforestation of mine wastes. Two case studies will be presented in more detail. The first tested the use of several low-density agricultural plant mixes to create favorable conditions for the establishment of forest species on tailings at the Canadian Malartic mine. The second focused on the use of wood chip mulch on waste rock to stimulate spontaneous forest recolonization at the Lapa mine. An interesting alternative to afforestation in forested areas is to focus on establishing pioneer herbaceous plants that are adapted to the constraints of mine soils but can create habitats able of supporting biodiversity. Thus, we have planted native, pollinating-insect-attractive flowering plants on several mine sites and monitored the insect populations visiting these new habitats. The results of these studies are promising for the ecological rehabilitation of mine sites, but there is still work to be done to ensure that the revegetated sites are healthy for the organisms that settle there and that they provide ecosystem services beneficial to society.

From 2013 to 2019, during the first phase, RIME's mandate was to develop environmental solutions covering the entire life cycle of mining operations to help companies in the sector achieve responsible mining development. While the mandate has not changed drastically in Phase II (2020–2026), new research themes have emerged, including knowledge sharing with communities and the influence of climatic conditions. This ambitious research program is led by an exceptional team of researchers, experts, professionals, and students. First and foremost, RIME is a team of over twenty professors with multidisciplinary and complementary skills who have developed unique synergies, providing global solutions to the industry's challenges. Around twenty technicians and professionals also contribute to research with their unique laboratory and field expertise. Last but not least, our students are our greatest strength. Coming from all over the world and boasting a wide range of educational backgrounds, they are the spearhead of our research and the next generation of researchers. Our partners also play a key role, with several representatives from each company taking an active part in the research. This collaboration allows us to address major environmental challenges facing the Québec mining sector and respond to the most urgent and important issues. Consequently, our research can be rapidly integrated into practice and have a tangible, immediate impact. It also enables us to effect change at the regulatory level and ensure that the best technologies and practices developed within RIME become industry standards.

In recent months, steps have been taken to approach the current mining partners regarding the launch of Phase III. The process is progressing well, and good news may be announced between now and next year. This new phase will allow the work carried out since 2013 on the Institute's key themes (mine site restoration, mine tailings management, mine water treatment, geochemical behaviour and reclamation of mine tailings, and knowledge sharing with communities) to continue, while further exploring new themes, such as biodiversity and revegetation, specific aspects of cold climates, and innovative approaches to the characterization and monitoring of storage areas.