Dissolve but not Precipitate

[bkazamel]

Hello,

 

New to GWB here! I have a system where chlorite (Clinochlore-14A) is allowed to dissolve, but not precipitate. I am wondering how to set this up in REACT. I tried setting the critical SI to an arbitrarily high value (99999), but that doesn't seem to work. I also went through Config --> Iteration, and unchecked precipitation, but that didn't make a difference in the model either. Attached image is the trend in chlorite abundance of the system, with crit SI set to 9999 and precipitation turned off. In the first 50 years, chlorite is dissolving, in the later years, it is precipitating (which does not make sense for my system). I apologize that I am unable to share the file because proprietary.

 

Any help would be greatly appreciated.

Cheers,

Brent

[Jia Wang]

Hello Brent,

Unchecking the precipitation option disables any new mineral from precipitating but if some amount of the mineral is in the system initially, it will precipitate or dissolve according to thermodynamics and the kinetic constraints prescribed. The critical saturation index parameter is used in mineral nucleation calculation, that is if your system initially contained none of the kinetic mineral, then the program uses the nucleus density and crit SI values to calculate initial mineral precipitation.

With a kinetic mineral reactions, you can use a custom rate law to specify a precipitation rate of 0 when the fluid is supersaturated with respect to Clinochlore14A . The simplest way of implementing this is to use a custom rate law script. Please see the example for this in section 5.1 Setting the rate law form directly in the GWB Reactions Modeling User Guide. 

Hope this helps,
Jia Wang

[Jia Wang]

Hello Brent, 

I am made a mistake in the above post. The example for the rate law script is in section 5.2 Rate law scripts and not section 5.1. 

Best regards,
Jia