There are three challenges facing scientists and engineers in mature fine tailings (MFT) treatment: fast solids/water separation, maximum water recovery, and consolidation of the final sediment. To date, polymeric flocculants have been widely used in the oil sands industry, alone or in combination with electrolyte coagulants, to the described challenges.
As a mixture of solids and liquid, tailings naturally stratify during settling according to Stokes' Law, with coarse particles concentrated at the bottom of a sediment bed and fines at the top. According to Stokes' Law, MFT viscosity is one of several factors affecting the particle settling velocity. In this paper, a new method using surfactant to reduce MFT viscosity, therefore, to accelerate tailings settling velocity and to improve tailings dewatering, will be presented. Experimental results indicate that with addition of a solid surfactant at 4,000 ppm and moderate shaking for 30 minutes, tailings viscosity was reduced from 6,300 cPs to 2,200 cPs at shear rate of 2.2 sec-1. The treated MFT sample was centrifuged at 1,000 G-force for 5 minutes. After that, the top layer can be easily poured out of the centrifuge tube. The solid content in the top layer is only 6.9%, but is as high as 80.2% in the bottom layer. In this way, the MFT was readily separated without addition of extra water.