Towards safe and sustainable – The GEOMINS project provides alternative methods to handle mine tailings
The disposal of mine tailings is always a big problem to mining industries and causes environmental issues even after the closure of a mine. Mine tailings are stored as slurry in the tailings ponds, which can cause contamination of surface water, ground water and soil.
The tailings are handled in several ways such as isolating them with cover layers, stabilizing them with chemicals or a combination of both. However, to achieve sustainability, it is recommended to minimize the landfilling of waste. Hence, the curiosity of researchers at the University of Oulu to use such mine tailings as construction materials resulted in the project GEOMINS.
From waste to value
The project aimed to use the alkali activation technology to convert the tailings material into concrete or ceramic-like materials, geopolymers. Tailings are rich in aluminosilicates and they can be used as precursors for geopolymers. However, pretreatment is needed to increase the reactive content of the tailings. In the GEOMINS project mechanical pretreatment resulted in the improvement of compressive strength. It was also proven that a high strength ceramic can be produced by thermally treating the tailings.
The most interesting part was the possibility of carbon capture in magnesium-based tailings. Mineralogy was favorable for incorporating the carbon dioxide in its structure, which also increased the mechanical performance of the construction materials produced during the process. Granulated, alkali-activated tailings were produced and cured with carbon dioxide to achieve a strength equivalent to commercial lightweight aggregates in the market.
More research to reach a sustainable future
The project results provide alternative methods of handling tailings in a safer way. Better understanding of Finnish tailings and their mineralogy paves way for possibilities to produce valuable materials such as aggregate, cement and composites.
Future work will focus in detail on the carbonation potential of Finnish tailings. It is also important to research the long-term durability aspects of the produced materials before taking them to market.