November 2004

HCI, the HCItasca office in Denver, is conducting ongoing work for COGEMA's McClean Lake Operation in the Athabasca Basin in Northern Saskatchewan. The primary aim of the project is to examine the treatment of raffinate and tailings to control arsenic concentrations in the tailings management facility. One completed phase of the project has examined arsenic released to pore waters from buried mill tailings, using a unique approach to estimate distribution coefficients in tailings based upon the concept of Equilibrium Partitioning in a Closed Systems (EPICS). Details of the method will be presented in a future issue of Applied Geochemistry. The sidebar figures show a hypothetical example of the effect of adding arsenic free water to a slurry of tailings and neutralized raffinate. If adsorbed arsenic is not present then simple dilution will occur. If adsorbed arsenic is present then a portion of it will be released, increasing the arsenic in the solution when compared to the simple dilution case. Plotting the inverse concentrations as a function of volume permits one to calculate the distribution coefficient (intercept/slope = Kd).

Additional work, which is nearing completion, includes preparation of papers that describe 1) laboratory measurements and use geochemical modeling to examine the formation of different minerals as the raffinate is neutralized, 2) tests that examine the behavior of arsenic as samples of tailings are aged using accelerated testing methods, and 3) studies on behavior of arsenic and other elements in the tailings management facility. For more information please contact Dr. John Mahoney at HCI.

Simple dilution (upper) vs. sorption (lower) and estimation of Kd

UDEC Version 4.0 prerelease is available now.
UDEC 4.0 has a number of new features that include: a complete graphical user interface, network key version, extended UDM models, block hide-and-show, block fill, mixed discretization, double-precision version, and more. See the UDEC 4.0 page for complete information.

Sales Notes

UDEC 3.1 is no longer for sale. Users who wish to purchase or upgrade current versions of UDEC will receive/upgrade to version 4.0. Please see the UDEC 4.0 page for a detailed explanation of the availability for purchase of UDEC.

With the release of PFC2D 3.1 just around the corner, version 3.0 is no longer being sold. However, current version 3.0 users have until November 30, 2004 to pre-purchase 3.1 at a discounted rate over the price of upgrading. New users who purchase PFC2D will immediately receive version 3.0 and will receive version 3.1 when it is officially released.

FLAC3D Version 3.0 prerelease is available now to those who have pre-purchased the code. See the FLAC3D 3.0 page for complete information.

UpdateAlert:

Updated since 9/1/2004:

Charles Fairhurst, Professor Emeritus of the University of Minnesota and founder of Itasca, was honored recently at the Fairhurst Colloquium, October 23-24, 2004, at the University of Minnesota. The event was a chance for friends, colleagues, and students to reflect on Charles' life and achievements. Itasca was a proud co-sponsor of the event. The program of the Colloquium is available from the University's site.

Congratulations, Charles!

FLAC Practical Applications Course
This course will focus on geotechnical modeling for urban construction, such as tunneling, cut-and-cover underground structures, and slope stability. The training will be hands-on, with minimum discussion on the theoretical basis of FLAC. Simple examples will demonstrate the principles and application of various code features (e.g., geo-material models, mechanical and groundwater analysis, structural support, factor-of-safety calculation). Participants are encouraged to bring their own design situations. The course will be offered December 1-3, 2004, at the Croydon office of the Itasca code agent in England, Mott MacDonald. For further information, please contact Yu Sheng Hsu, the code representative at Mott MacDonald.

Q: "When working on a FLAC model that has multiple "branches" in the project tree, is there an easy way to set FLAC to run through each branch automatically?"

A: Yes, by using the sometimes easy-to-miss "rebuild unsaved states" command on the "project options" tool. Be sure to delete or remove all SAV files that you plan to rebuild.

Code users who did not have the chance to attend the recent UDEC/3DEC and PFC conferences may want to consider obtaining a copy of the proceedings from these events.

Shimizu, Y., R. D. Hart and P. Cundall, Eds. (2004) Numerical Modeling in Micromechanics Via Particle Methods - 2004. Proceedings of the 2nd International PFC Symposium, Kyoto, Japan, October 2004. Leiden: Balkema.

Konietzky, H., Ed. (2004) Numerical Modeling of Discrete Materials in Geotechnical Engineering, Civil Engineering & Earth Sciences. 1st International UDEC/3DEC Symposium, Bochum, Germany, September 2004. Leiden: Balkema.

These proceedings (as well as proceedings from earlier FLAC and PFC conferences) are available from A.A. Balkema Publishers. They are among the richest resources in print when it comes to discussion of the application of Itasca codes.

   ©2004 HCItasca, Inc.

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