Effects of sand and flocculation on dewaterability of kaolin slurries aimed at treating mature oil sands tailings

In guiding dewatering of oil sands tailings we measured dewaterability of as-mined kaolin when sand was added as a process aid to both the dispersed and flocculated kaolin slurries. In batch tests, gravitational settling, inverse permeability R, and compressive yield stress Py were measured as functions of solids volume fractions Phi, as sand increased in the mixtures. We measured Py(Phi) for flocculated kaolin with an equal sand fraction, a flocculated diluted kaolin, flocculated diluted mature fine tailings (MFT), gel-point kaolin and MFT. Results indicated that an optimal quantity of sand in mixtures with kaolin increased the consolidated volume fraction of solids at equivalent compressive yield stress, reduced hindered settling function values, and enhanced gravitational settling rate. Py(Phi) vs Phi plots for gel-point volume fractions of kaolin and MFT showed MFT to be more compressible, but needed a much longer time to dewater. Two flocculants had similar Py(Phi)) vs Phi responses when tested with either kaolin or MFT. Flocculated kaolin and MFT exhibited rapid settling, but flocculated was less compressible than unflocculated. Py(4)) vs 4) plots for both kaolin and MFT that were flocculated after dilution produced a crossover at Py=121 kPa and Phi = 0.41. The Py(Phi)) vs Phi data from all tests followed power law. Crown Copyright (C) 2017 Published by Elsevier B.V. on behalf of Institution of Chemical Engineers. All rights reserved.