Enhancing the safety and surveillance of tailings storage facilities in cold climates
Thesis event information
Date and time of the thesis defence
Place of the thesis defence
University of Oulu, Linnanmaa, auditorium L10
Topic of the dissertation
Enhancing the safety and surveillance of tailings storage facilities in cold climates
Doctoral candidate
Master of Science Anne Tuomela
Faculty and unit
University of Oulu Graduate School, Faculty of Technology, Civil Engineering (CIV) Research Unit
Subject of study
Civil Engineering
Opponent
Professor Leena Korkiala-Tanttu, Aalto University
Custos
Professor Rauno Heikkilä, University of Oulu
Enhancing the safety and surveillance of tailings storage facilities in cold climates
The mining industry, both in Finland and worldwide, generates a lot of unused by-products. One of the most significant by-products is tailings, Tailings is a generic term for material that is formed as a surplus in the enrichment process when the most economically viable compounds, such as precious metals, have been separated from ore.
Sustainable mining aims to reduce the load on the environment and find ways to exploit the materials of the side streams. However, northern conditions, such as the presence of snow and ice, create their own challenges for exploitation.
The doctoral dissertation investigated the behaviour of tailings in cold climate areas. The study analysed how tailings from metal ore mines freeze and how their disposal can be improved from a geotechnical perspective. The examined tailings samples behaved like natural materials during freezing, and the frost-susceptible classifications developed for natural materials were suitable for use in the tailings studied as well. In one tailings storage facility (TSF), the penetration of frost in the tailings pond was measured over the winter. The functionality of the one-dimensional simulation model was verified with the help of the measurement results. The model can be used to assess, for example, a disposal method’s risk of generating permafrost layers in a pond. In addition, a method was developed to select an appropriate test method for estimating the frost susceptibility of mine tailings.
The use of drones was also tested in several ways. In this work, unmanned aerial vehicle measurements were used to monitor changes in a tailings storage facility at one of the mines from 2015 to 2017. Drones were found to be a practical tool for monitoring and collecting tailings surface elevation data with an accuracy of about a decimetre. Surface maps generated from the data were useful for tracking settlements and patterns. The method was found to have several possibilities and can be used in the future, for example, in planning, designing, and dimensioning of TSFs and managing the filling during the use of facilities.
In addition, the study collected information from the literature on composite structures used in the bottom of tailings ponds, which in Finland have attracted much debate because of leaks. According to the previous research, high-quality foundation structures reduce leakages into the environment. In this study, a framework of action was developed to improve the construction process by designing the most qualitatively functional structures. The results obtained in this dissertation can be used extensively in the mining industry.
Sustainable mining aims to reduce the load on the environment and find ways to exploit the materials of the side streams. However, northern conditions, such as the presence of snow and ice, create their own challenges for exploitation.
The doctoral dissertation investigated the behaviour of tailings in cold climate areas. The study analysed how tailings from metal ore mines freeze and how their disposal can be improved from a geotechnical perspective. The examined tailings samples behaved like natural materials during freezing, and the frost-susceptible classifications developed for natural materials were suitable for use in the tailings studied as well. In one tailings storage facility (TSF), the penetration of frost in the tailings pond was measured over the winter. The functionality of the one-dimensional simulation model was verified with the help of the measurement results. The model can be used to assess, for example, a disposal method’s risk of generating permafrost layers in a pond. In addition, a method was developed to select an appropriate test method for estimating the frost susceptibility of mine tailings.
The use of drones was also tested in several ways. In this work, unmanned aerial vehicle measurements were used to monitor changes in a tailings storage facility at one of the mines from 2015 to 2017. Drones were found to be a practical tool for monitoring and collecting tailings surface elevation data with an accuracy of about a decimetre. Surface maps generated from the data were useful for tracking settlements and patterns. The method was found to have several possibilities and can be used in the future, for example, in planning, designing, and dimensioning of TSFs and managing the filling during the use of facilities.
In addition, the study collected information from the literature on composite structures used in the bottom of tailings ponds, which in Finland have attracted much debate because of leaks. According to the previous research, high-quality foundation structures reduce leakages into the environment. In this study, a framework of action was developed to improve the construction process by designing the most qualitatively functional structures. The results obtained in this dissertation can be used extensively in the mining industry.
Last updated: 23.1.2024