Yield stresses of mixtures with bimodal size distributions

• Author / Creator

  Rahman, Md. Hafizur

• The addition of coarse particles to a flocculating fine particle slurry increases the Bingham yield stress of the resulting mixture, which can drastically alter the laminar-to-turbulent transition velocity. The objective of this study is to quantify the effect of coarse particle size and volume concentration on mixture rheology. Fine particle (kaolin) mixtures of 10% to 22% (by volume) were prepared, to which sand particles were added to provide a coarse solid concentration of 5% to 20% (by volume). Sand particles of two different sizes – 90 and 190 microns – were added and these kaolin-sand-water mixtures tested with a concentric cylinder viscometer. At higher total solids concentrations, the Bingham yield stress of the bimodal mixture can increase by as much as 80% over that of a kaolin-only slurry. Coarse particle diameter had little effect. This study demonstrates that the use of existing correlations should be eschewed. System-specific high-quality measurements are necessary.

• Subjects / Keywords

  • Coarse particle concentration
  • Yield stress
  • Coarse particle size
  • Viscometer
  • Fine particle slurry

• Graduation date

  Spring 2011

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3FK5N

• 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.