Role of Preconditioning Cationic Zetag Flocculant in Enhancing Mature Fine Tailings Flocculation

Abstract

The ongoing generation of mature fine tailings (MFT) or fluid fine tailings (FFT) from surface mining activities of the oil sands industry in Canada has been a contentious issue for many years. In the absence of large-scale processing facilities, many far-reaching consequences from extensive stockpiling of FFT will plague the industry for many years to come. Application of polymeric flocculants to treating FFT for efficient solid–water separation has been well-established. However, most commercially used flocculants carry a negative charge and yield incomplete capture of suspended fine solids and hence relatively turbid recycle water. This inefficient flocculation of fine solids limits the effort of process water recycling and severely strains most downstream dewatering processes, such as filtration. Cationic flocculants offer a promising alternative in terms of overall solids capture and recycle water quality, although the associated high cost hindered much of its commercial applications. In this work, we introduce a method to deploy a commercial cationic flocculant (Zetag 8110). Heating and increasing pH of the flocculant solution in oil sands process water led to more effective fines flocculation and a supernatant of <200 nephelometric turbidity units (NTU), at ∼75% less dosage than the direct use of Zetag solution without any form of preconditioning. The insights gained from this study can lead to a better flocculant design, utilization, and process economics for FFT treatment.