Dominant mineral

[ANar]

Hi everybody,

I have a solution with some major ions dissolved and put in it the element of my concern. For the solubility limit calculation (maximum aqeous concentration) to be calculated by PHREEQC I intend to a selected mineral (let say 10 moles) and let it to be in equilibrium with the solution (SI=0). For selection the most dominant mineral determining the solubility limit at fixed conditions I believe it is not enough to look at the highest SI. My approach to find out the dominant mineral is to add some amount of element of concern into solution and to put its mineral phases (and some others) into EQUILIBRIUM_PHASES block with 0 0. Based final moles in Phase assemble of particular I decide the dominant mineral (largest amount). Is this approach correct?

I am able to draw predominance diagram with PHREEPLOT with solution composition considered and I do believe that the conclusion about the dominant one should match as PHREEPLOT is executing PHREEQC.

Many thanks for any comments.

[dlparkhurst]

Assuming your solution is supersaturated with one or more of your minerals of interest, I would set the moles of each to zero in the EQUILIBRIUM_PHASES definition. By using non zero values, you may get quite a bit of reaction of minerals dissolving and precipitating, and your solution may look very different than the starting solution.