Trace element addition to mineral phases (water-rock interaction)

[Nicole Mikkelson]

I am trying to simulate water quality of runoff and seepage from a waste rock dump.

I currently have the mineralogy from XRD analysis and trace element concentrations of waste rock.

 

I would like to determine the chemistry resulting from the interaction of rain with for example; Rhyodacite or Andesite.

 

I have entered the Basis solution along with the kinetic reactants (minerals present as per XRD results) however would like to know how to incorporate additional trace elements.

 

For example the mineral phases present include;

Quartz

Anorthite

Calcite

Anatase

Pyrite

Kaolinite

Montmorillonite.

 

How can I include trace quanities of As, Pb, Ni, V ect?

 

Thank you for your help

[Brian Farrell]

Hi Nicole,

 

Unfortunately, dealing with trace elements can be difficult, because they often appear as impurities or substitutions within more common minerals rather than as pure minerals. You could, however, assume that the elements you mentioned (As, Pb, Ni, V) do in fact exist as pure minerals in equilibrium with your initial waste rock pile by swapping them into the Basis pane. Perhaps you could create a diagram in Act2 for each particular element of interest, being sure to include your system's chemistry, then choose the mineral that is predominant at your system's pH, Eh, conc., etc. values.

 

You can also force these trace elements to react by adding a proxy mineral to the Reactants pane, or an oxide of that element. Basically as your dilute rainwater reacts with your waste pile, some amount of these oxides would dissolve uniformly over the course of the reaction path. Just a few ideas.

 

Hope this helps,

Brian Farrell

Aqueous Solutions LLC