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JohnLiang

About ACT2 result problem

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Hello,

Our client has a problem as follows:

When we create phase diagram with Act2 program, we don't know why it has difference between existing Fe and without Fe.

Please refer to the attached files which are these two cases.

Please help us.

Thanks a lot.

John

inFe.ac2

noFe.ac2

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Dear John,

Act2, shows the stability of minerals and predominance of aqueous species for a single “element” or component, the diagram species, over the chosen axes: pH and Eh in your case. They’re allowed to complex with any of the ligands that you specify in the “in the presence of” field. Thus, when you add Fe++ to the "in the presence of field", you define the activity of Fe++ and allow it to make complexes with your main species. Thus, theoretically, you should get a different plot from when you don't have Fe++However, there are a few things in your plot that I think might not be set correctly:

1. If you are looking at the speciation of sulfur, there is no need to swap Pyrite in. Pyrite will show up on your plot if it is stable over the defined pH-Eh range.

2. if you know that your complexing species reacts under changing Eh or pH, you can include that in your graph using the "speciate over x”, “speciate over y”, or “speciate over x-y" options from the pulldown next to where you define your complexing species activity. For example., Fe++ would speciate and/or change oxidation state in response to changing pH and Eh.

Finally, to check your simulated environment go to the “plot” plane --> “view results” to see all the reactions and the activity of species in your system.

Hope this helps.

Bests,

Melika Sharifi

Aqueous Solutions LLC

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Dear Melika,

If we want to know what kind of situation the pyrite will dissolve, could we use Aac2 to check it?

Thank you very much.

 

Best regards, 

Betty

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Dear Betty,

Act2 can be useful for understanding the geochemical conditions under which various mineral are stable. It calculates and plots activity-activity diagrams. This class of diagrams shows the stability of minerals and the predominance of aqueous species in chemical systems. A species activity, gas fugacity, activity or fugacity ratio, pH, Eh, or pe may serve as an axis variable. 

If you are trying to simulate reaction paths and precipitation/dissolution of minerals, you may need to use React. You specify the concentration of fluid components in your initial system, define a reaction path, and React computes the change in your initial system as it undergoes the defined reaction.

Hope this helps.

Bests,

Melika Sharifi,

Aqueous Solutions LLC

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