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Reactive Transport - Newton Raphson


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Hi Brian


Once again thanks for the workshop in Perth last week, it was very good.


I'm working on a problem whereby the project involves injecting aquifer mined materials back into the aquifer (it's a long story...).


The issue is that we have the calculated pyrite oxidation rates and acidity generation rates for the material, and I want to show the case where the material is not neutralised and is injected to the aquifer. To do this I have my groundwaters in the GSS (attached) and am using a 'mix' water as representative. I put this water through SpecE8, and transfer the results to REACT. I react H2SO4 at a rate commensurate with the acid generation rate quantitative data, to mimic leachate generation in the overburden above ground (as per the attached REACT file). All good at this point.


To check, I use my GSS mix water direct from SpecE8 results as the new basis in REACT, following pick up > acidified leach to reactant. The run is good and works fine (file not attached). To me this represents the leach mixing with the groundwater at point of injection.


However the issue is where I use the speciated mix water from SpecE8 as initial in Xt1, and use the results from REACT (leach) as inlet. No matter what i do I get one or more 'newton raphson' errors and just cannot get convergence (Xt1 file attached). My conceptual model is that the leach is introduced for X period of time into the initial water so that i can calibrate against offset monitoring wells (in theory).


The waters are fairly 'exotic' and I have included titanium and zircon to mimic the mineral phases (a key resource is ilmenite) - to get the thermodynamic side working, i switched to the V8 R6 database...for all app runs.


I have tried a less complicated water (i.e. consecutively removing species flagged as being newton raphson problematic) but have had no joy.


Any tips greatly appreciated!!




JamesLWC CP-01 UGM Backfill_001.x1tLWC CP-01 UGM Leach 001.reaLWC CP-01 UGM Mix Water Spec 001.sp8UGM V2.gss

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