PHREEQC, Solubility graphs from a quaternary mix of salt

[nicksingh]

Hi,

I am new to PHREEQC and wanted to use the sw to get an idea of precipitation rates of specific salts from a mixed salts solution while varying the temperature.

I noted that the sw has data on sylvite and halite phases but not on hydrophilite, sinjarite or antarcticite. 

Is there a way to obtain solubility (precipitation) information of salts - CaCl2, NaCl, KCl from a quaternary mix of NaCl10%-KCl 5%-20%CaCl2- H20 solution? 

I would like to get an idea of ratio of salts precipitated (and types) vs amount left in solution as water is evaporated? And the final composition of 30%CaCl2  in solution with residuals of KCl and NaCl for different volume reductions?

I would welcome your suggestions.

Thanks, Nick

[dlparkhurst]

If you have the log Ks for the minerals, you can use PHASES to define them. Antarcticite is included in the frezchem.dat database.

Even without adding new minerals, for starters you could determine the predicted stable phase assemblage for the minerals that are included in pitzer.dat or frezchem.dat, provided the concentrations are not so large as to cause numerical issues.

Rates of precipitation is another matter.  There are no rate expressions for these minerals that I know of, so you would be on your own to find rate expressions in the literature or develop your own for your system.