Geotechnical Society of Edmonton

NEWS 2005

Posted September 26, 2005

September 29, 2005

2005 GSE Annual Wine and Cheese and University of Alberta Student Presentations

Freeze Separation of Contaminants from Salt Contaminated Water

Nick Beier, M.Sc. Candidate, Geo-environmental Engineering Program
Mine waste water management in the Canadian oil sands industry has become a major concern due to increased production rates, cost and disturbance associated with limited storage capacity and treatment costs for the waste water. Reuse of the clarified water results in the steady increase of organic and inorganic contaminant concentrations in the recycle water. Using a specially designed flume housed in a cold room, trickle freeze separation was evaluated for contaminant separation of saline solutions. Saline water was used as a surrogate for mine waste water. Several experiments were conducted at various ambient temperatures, salt concentrations and mass flow rates. At an ambient temperature of -15oC, separation and concentration of up to 92 % of the salt mass was possible in 22 to 53 % of the original volume depending on the source concentration.

Role of Rheological Properties in Tailings Characterization

Yetim Mihiretu, Ph.D. Candidate, Geotechnical Engineering Program.
Rheological characterization provides geotechnical /geoenvironmental engineers with the necessary tools for prediction of slurry flow behavior and segregation potential in the tailings slurries. In the current study on the fundamental physics of segregation, the vane shear method was implemented to study the rheological response of slurry. The vane shear method is compared to other rheometric methods and the validity of the approach is presented. Results from a study of the vane shear response due to variations in particle size distribution and composition are also presented. In general, the yield stress showed an exponential increase with increase in solids concentration. However, reduced yield stresses were observed for a slurry composition comprising either silt-size or sand-size fractions. A semi-empirical fractal theory for yield stress as a function of solids concentration showed good agreement with experimental data for the fine-grained slurry. The role of aqueous chemistry was also studied for the fine grained slurry used in this study. In particular, the yield stress was found to be insensitive for pH values in the acidic and neutral range, while in the basic range it showed significant sensitivity depending upon the type of chemical ( Ca(OH)2 and NaOH ) used to achieve the high pH. The presentation concludes with a discussion on the application of rheological properties in the study of slurry segregation processes.

Location: University of Alberta Faculty Club
Time: 5:30PM Reception, Presentations start at 6:30PM
Date: Thursday, September 29, 2005
Cost: GSE Members: $5, Students: $5 (includes GSE Membership), Non-Members: $10
Register: Space limited.
Please confirm attendance by 12:00pm, Tuesday September 27
by emailing kent.bannister@amec.com

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