Application of Dewatering Technologies in Production of Robust Non-Segregating Tailings

• Author / Creator

  Moussavi Nik, Reza

• One of the current technologies used by the oil sands industry to reduce the volume of fluid fine tailings and create a dry landscape is production of CT (Composite Tailings) and NST (Non-Segregating Tailings). CT and NST are engineered tailings streams obtained by recombination of fines (MFT or TT) and coarse tailings (sand) plus a chemical amendment. If produced on-spec, the main advantage of CT/NST would be its improved dewatering behavior and rapid release of relatively clear water during the hindered settling and self-weight consolidation, while a majority of the fine particles are entrapped within the matrix of its coarser fraction (sand).

  Production of a robust CT/NST at a commercial scale has been a challenge for the industry. While CT/NST has been expected to be non-segregating when discharged, partial segregation and release and re-suspension of the fines has been observed following deposition. To produce a robust CT/NST and reduce its susceptibility to segregation, the yield stress of the carrier fluid (i.e. fines + water) must be enhanced. This can be achieved by increasing the solids content of CT/NST.

  The present research reviewed the different methods of solid-liquid separation and experimentally investigated the possible application of some of these methods for improving the quality of CT/NST. A major part of this research was focused on dewatering of MFT and using it as a component for making CT/NST. A batch filtering centrifuge was utilized to dewater MFT samples received from three different operators and the major factors affecting the process of centrifugal filtration were investigated. The resultant dewatered MFT samples were mixed with a mixture of sand and pond water to produce CT/NST with higher solids content. The depositional behaviour and robustness of the produced CT/NST samples were investigated using a flume apparatus. The flow profile and variations of solids content and SFR (Sand to Fines Ratio) were identified for each deposition test, also the yield stress of the CT/NST samples was evaluated using a strain-controlled viscometer and vane spindles. The results of this study indicate that using dewatered MFT promotes production of robust CT/NST streams achieved with lower dosage of chemical additives.

• Subjects / Keywords

  • Composite tailings
  • NST
  • Oil sands tailings
  • Filtering centrifuge
  • CT
  • Dewatering
  • Non-segregating
  • Centrifugal filtration
  • Solid-liquid separation

• Graduation date

  Fall 2013

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3JQ0T37Q

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.