Two-stage flocculation of fluid fine tailings

Abstract

A method for treating and disposal of fluid fine tailings utilizes two stages of thickening prior to disposal of the thickened tailings. The fluid fine tailings are adjusted to a sand-to-fines ratio of 0.5 to 1.3 using hydrocyclones or centrifuges in required. In a first stage of thickening a first flocculant is added to the fluid fine tailings which are fed to one or more conventional thickeners to produce a pumpable thickened tailings underflow having a solids content of between about 20 wt % to 40 wt %. The pumpable thickened tailings underflow is centrifugally pumped through a pipeline towards a disposal area. Adjacent the disposal area a second flocculant is added to the pumpable tailings underflow in a second stage of thickening to flocculate the tailings sufficient to produce a secondary thickened tailings underflow which when deposited has a solids content of about 50 wt % or higher at least one day after disposal. Alternatively, the second flocculant can be added prior to a paste thickener located adjacent the disposal area to further thicken the secondary thickened tailings underflow to a solids content of about 65 wt % for direct disposal at the disposal area.

Dependencies are inferred from the claim text.