The effect of flocculant on the geotechnical properties of mature fine tailings

Abstract

When oil sands tailings are deposited in a tailing pond, they settle and segregate to create a layer of stagnant water on top that is reused in oil extraction and a dense mixture of clay, silt and water on the bottom which is referred to as mature fine tailings (MFT). Dewatering of MFT is a problem due to its very high fines content and relatively low solid content. Atmospheric drying offers a possible solution to this problem. In this technique, MFT are pumped or dredged out of the pond and mixed with polymers that helps to accelerate the release of water from the fines, and then placed on a sloped drying area in a thin layer. When the released water runs off the remaining flocculated MFT will dry to the desired moisture content for removal and replacement in the mine or for subsequent lifts. This paper presents a laboratory study on the flocculated MFT. With a senes of tests the basic properties and consolidation and desiccation behavior of flocculated MFT are assessed. The results were compared with ohginal untreated MFT, which confirmed that in case flocculants are properly mixed with MFT, they have a positive effect on the dewatenng rate of the MFT. However, the final exposed to atmospheric drying can be significantly larger than the untreated MFT. The results provide a useful reference for future pilot-scale tests and commercial implementation of the atmosphenc drying method on flocculated MFT.