iterations exceeded 100

[Sergio913]

Hello everybody

Im beginner in phreeqc and i have error in the iteration, how can i modify the iterations?

this is my code, and dont converge

       temp      115
       pH        8.49
       pe        4
       redox     pe
       units     mg/l
       density   1.014
       Ca               429.60            
       Mg               1361.00         
       Na              11429.00         
   Alkalinity       47.58 as HCO3
   Cl         20040
       S(6)           3500.00         
     -water    1 # kg

thanks

[dlparkhurst]

The immediate problem is with the definition of Alkalinity. If you remove the Alkalinity definition, the solution will run, and it calculates an alkalinity of 6.9e-3 equivalents per kgs, mostly due to the ion pair MgOH+. So, when you define the total alkalinity as 48 mg/L, which corresponds to <1e-3 equivalents per kgs, there is no way to find a numerical solution. There is no way to have the Mg concentration, pH, and alkalinity simultaneously.

The calculation will also run if you define C(4) instead of Alkalinity. At this pH, carbonate alkalinity is nearly equal to total dissolved inorganic carbon.

If the alkalinity is a reliable analysis, then the problem may ultimately be the reliability of the aqueous model at 115 C.