Impact of drying on geo-environmental properties of mature fine tailings pre-dewatered with super absorbent polymer

Abstract

Oil sand operations in Alberta generate a large amount of waste tailings in the form of slurry that is rich with fine particles. The surface disposal of this waste has created several environmental problems. Furthermore, strict governmental regulations on the disposal of such a huge amount of waste called mature fine tailing in tailing ponds have compelled the industry to develop new techniques that are more sustainable and environmentally friendly. Hence, in this study, a new technique that uses a super absorbent polymer to dewater mature fine tailings is investigated by adding 1% by weight polymer to the mature fine tailings. The pre-dewatered mature fine tailings are then exposed to evaporation and the results in terms of changes to the volumetric water content, electrical conductivity, geochemistry, microstructure and permeability are reported. The volumetric water content and electrical conductivity have the same behavior such that as the water content decreases, the electrical conductivity also decreases. In term of changes to the chemistry, the super absorbent polymer reduces the ion concentration of the pore water with uptake of the major cations in its polymer chains. Scanning electron microscopy shows that there is a more compacted clay matrix in the pre-dewatered mature fine tailings as opposed to the raw material. Hence, with further restriction of flow in the pre-dewatering of mature fine tailings with the super absorbent polymer, the hydraulic conductivity is also reduced.