Using surface geopolymerization reactions to strengthen Athabasca oil sands mature fine tailings

Abstract

AbstractThis paper describes a novel method to address the oil sands tailings reclamation problem using surface geopolymerization reactions. Geopolymerization involves dissolution of aluminosilicate minerals and re‐solidification reactions that result in the formation of three‐dimensional inorganic polymers of significant strengths. Since the fines present in oil sands mature fine tailings (MFT) mainly consist of aluminosilicate minerals, or clay minerals, it is hypothesized that by adding appropriate reagents, the surface of the clay minerals can be activated and go through geopolymerization reaction under ambient conditions. The resulting geopolymeric species formed on the clay minerals will bind the clay particles together and strengthen the tailings even without further dewatering.Geopolymerization was tested on 0.51 g/g (51 wt%) solids centrifuged MFT and its shear strength was observed to increase from 115 to 4880 Pa in 90 days when treated with 40 kg of sodium hydroxide and 60 kg sodium silicate per tonne of dry MFT solids. Similarly, the shear strength of 0.48 g/g (48 wt%) solids polymer flocculated MFT increased from 395 to 3950 Pa 90 days after the addition of the same dosages of sodium hydroxide and sodium silicate. Tests conducted on a geopolymerized model kaolinite sample showed that under the test conditions, the geopolymerization reaction only occurs on the surface of the kaolinite at the indicated dosages. The surface geopolymers held the kaolinite particles together, leading to an increase in its shear strength.