| Environnement, ingénierie & développement |  |
N°64 - Juin 2013
1. Éditorial n°64 Déchets Sciences et Techniques
Comme annoncé au précédent numéro, nous publions ici une sélection d’articles tirés du symposium sur l’Environnement et les Mines, dont la 4e édition s’est tenue en 2011 à Rouyn-Noranda, Québec, Canada. Ce symposium se distingue tant par sa formule (qui associe des conférences scientifiques et des communications par affiches à des sessions techniques de pointe, des cours intensifs, et des visites de sites miniers) que par la diversité des participants (scientifiques, représentants d’organismes publics, opérateurs miniers, fournisseurs de services et d’équipements, étudiants, etc.).L’édition 2011 a réuni plus de 330 participants venant du Québec, d’autres provinces canadiennes, des Etats-Unis, du Burkina Faso, du Maroc, de France et de Grande- Bretagne. Au total, plus de 27 conférences ont été présentées dans 7 sessions allant du remblayage souterrain à la restauration des sites en passant par la qualité des eaux et les aspects législatifs et réglementaires. L’ensemble des présentations, orales et affichées, sont disponibles sur DVD auprès de l’institut canadien des mines et de la métallurgie (ICM). Les relations qu’entretiennent l’INSA de Lyon et l’université du Québec en Abitibi Témiscaminque (UQAT) nous donnent l’opportunité et le plaisir de présenter dans ce numéro de DST une sélection d’articles illustratifs des champs couverts par le congrès.
2. Stabilisation de l’arsenic dans les remblais miniers en pâte cimentée
Backfilling of underground mines is now widely used in hard rock mines. It provides numerous benefits regarding ore recover y (more complete and more flexible ore recover y) and the reduction of environmental impacts (storage of problematic tailings). Cemented paste backfill (CPB) is the main method used in modern mines among the various types of mine backfills, because it provides benefits when used with reactive sulphide mine tailings.These tailings contain frequently iron sulphides (pyrite and pyrrhotite), and can also contain sulphides associated with metals (e.g. copper, zinc, etc.) or metalloids (e.g. arsenic). In the present study, CPB made of As-bearing sulphide tailings, and CPB artificially spiked with As have been prepared, in order to assess the potential for As to be stabilized in these matrices. The chemico-mineralogical speciation of As and the geochemical behaviour of As in these CPB have been studied in details. Moreover, As sorption tests on hydrated cementitious phases as well as a characterization of the microstructure of CPB samples have been carried out to bring complementar y information and to conclude about the interest of As stabilization in CPB.
3. Comportement géochimique et hydrogéologique des stériles de la mine Lac Tio
Chemical reactions occurring between mine wastes and their environment can lead to water contamination, even at near-neutral pH; this phenomenon is called Contaminated Neutral Drainage (CND). CND generation is observed at the Lac Tio mine site where Ni concentration at some exfiltration points occasionally exceeds the regulation criteria.The Lac Tio mine exploits the largest massive ilmetite ore body in the world. A research program was undertaken in 2005 to better understand the phenomena leading to mine water contamination and to help identifying the most appropriate reclamation approaches. More specifically, the waste rock geochemical behaviour was first characterized and analyzed at different scales (in the laborator y and in the field). Geochemical modeling was also performed to better understand and eventually predict the geochemical behaviour. Since this behaviour is tightly related to water movement in the waste rocks, some efforts were also dedicated to the material’s hydrogeological characterization and to the evaluation of the internal structure of the main waste rock pile. Results showed that the geochemical behaviour of the different waste rock types is mainly a function of the hémo-ilmenite content and of the age of the waste.The hydrogeological tests allowed estimating the in situ saturated hydraulic conductivity variability (usually between 10-1 and 10-3 cm/s). The flow velocity into the pile was estimated to values less than 0.35 cm/day using numerical […]
4. Les travaux du projet BNQ 21000 : des mécanismes pour opérationnaliser le développement durable au sein des entreprises et autres organisations du Québec
“Project BNQ 21000” is directly linked to the Québec government’s Sustainable Development Strategy 2008-2013, which promotes voluntary approaches to sustainable development of civil society, including business, progressing towards this end. It is in the context of this strategy that is proposed the BNQ 21000 Approach to organizations in Québec. BNQ 21000 Approach is a standard guide and a comprehensive method to promote and accelerate the recognition and implementation of the principles of sustainable development.In a complementary perspective to the BNQ 21000 Standard, BNQ 21000 Method is currently being pilot projects in more than 60 Québec companies. The purpose of this testing phase is to test the normative guide in a practical way and to help validate and improve an approach and tools to meet the needs of companies in terms of sustainability management. In this regard, more than a dozen companies in the Québec mining industry participate in this experiment in the pilot project of the Quebec Mining Association (QMA). In words, the BNQ 21000 standard and 21000 BNQ Method will base the whole Approach BNQ 21000 and can be summarized by the slogan: Driving sustainable development of responsible organization
5. Revue de divers aspects liés à la stabilité géotechnique des ouvrages de retenue de résidus miniers: Partie I – Mise en contexte et caractéristiques générales
Dikes constructed for tailings impoundment must be designed to support critical loads during mining operation and after closure. Various incidents that occurred over the last few years around the globe have shown that ensuring the geotechnical stability of such retaining works still raises numerous challenges. Many organisations are reviewing their guidelines for the design criteria and methods of analysis to evaluate the stability of tailings dikes. In this first article, the general nature of the problem is reviewed, together with typical properties of tailings from hard rock mines and characteristics of dikes. The second article will address the main factors that affect their geotechnical stability.
6. Revue de divers aspects liés à la stabilité géotechnique des ouvrages de retenue de résidus miniers: Partie II – Analyse et conception
Tailings dikes are still prone to relatively frequent failures due to geotechnical instability. The general problem related to stability of such retaining works has been presented in part I. In this part II, the main factors that affect the stability of dikes are reviewed. Typical tools used to analyse the behavior of these engineering works are described, with an emphasis on the effects of critical events such as large precipitations and earthquakes. The article also discusses new avenues that help control the problems, including the use of waste rock inclusions in the tailings impoundment.