expanding the HMW database (include Fe, Al)

[Tom Meuzelaar]

[admin notice: the below is from the former GWB users group email distribution list. This message was originally posted 12/5/2005]

Posted by: Grant Douglas

Dear GWB users,

I have a question regarding the modelling of

evaporation in React of

often highly acidic and saline to hypersaline

drainwaters. While I can

evaporate and follow the course of salts that

precipitate, pH and major

ions using the hmw database (and this agrees fairly

well with actual

evaporation expts), a challenge arises when I want to

look at the

precipitation of a range of Al- and Fe-based minerals

such as alunite,

jurbanite and ferrihydrite. Given that these acid

drainwaters are

shallow and well-mixed I would like to keep CO2 and O2

near atmospheric

and Fe trivalent.

Given only some elements are available in the hmw,

thermo_pitzer and/or

other databases, is there a way to build a single

database that will

cope with the high salinities and also be able to

accurately predict

the

precipitation of various Al- and Fe-containing phases

under the acidic

and saline conditions?

Background information is as follows: GWB 6.0 Pro

using React on

Windows

XP. A simple script to evaporate drainwa! ter to near

dryness

(simulating

natural events) using the hmw database is attached.

Many thanks to anyone that can assist.

Grant Douglas

Posted by: Mark Logsdon

HI Grant,

A good place to start is Ptacek, CJ and DW Blowes, 2003. Geochemistry of Concentrated Waters at Mine-Waste Sites, in JL Jambor, DW Blowes and AIM Ritchie (Eds) Environmental Aspects of Mine Wastes, Mineralogical Association of Canada, Short Course Series Volume 31, p. 239-252.

Drs. Ptacek and Blowes discuss the model-development process and expansion of the databases on pages 242-244. There is an extenisve bibliograpohy, with citations to data sets that you may wish to consider.

Hope this helps.

Mark