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Geochemist's Workbench Support Forum


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About forrie

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  1. Hi This is a small but annoying problem: Why is some mineral saturation not shown in GSS or React when trying to plot it? (the minerals are not suppressed and all components of the minerals were included) In a Xt1 model I have performed on water with similar composition the mineral saturation is given in output using the same databases. Regards Johan
  2. forrie

    script: kinetic rate

    Hi Brian Anything yet?
  3. Hi Catriona With a lot of kinetic minerals I sometimes give all of them a zero surface area to start with. then I add the surface area (SA) of each mineral one after the other (running the model inbetween) until I see where is the problem (the faster reacting minerals). It is difficult to know the exact mineral SA. Sometimes I also reduce the SA of the silicates (then the model often runs)and slightly increases it until I feel it sorts of reflect the conditions I want to model. It would be interesting to see the model in X1t also. Regards Johan
  4. forrie

    script: kinetic rate

    Hi Brian When I replace the built in rate law with the script the mineral does not react. I thought that maybe it is again the script that is the problem as no reaction takes place. However if I specify the first condition of the script in the built in law then it runs perfectly. But I would like to run the second condition also. Regards Johan Column test pyr.x1t
  5. Hi Brian I am trying to simulate acidification over time in a column test. Can you please tell me what is wrong with my script for a kinetic mineral below... IF pH > 3 THEN 20 ELSE 40 20: rate = 6.4565e-13 * surface * (1 - Q/K) * (activity("H+")^-0.11) * (activity("O2(aq)")^0.5) GOTO 60 40: rate = rate_con * surface * (1 - Q/K) * (activity("Fe+++")^0.93) * (activity("Fe++")^-0.4) 60: RETURN rate Thanks Johan
  6. forrie

    Custom rate law - script

    Hi Brian Thank so much for your help! Regards Johan
  7. forrie

    Custom rate law - script

    Hi Brian I have attached the .rea and the .bas files. I just changed the .bas extention to .txt as it seems that one cannot upload a .bas file. The .rea script is just an example of what I am trying to do. Actually my model is in Xt1, however I have deleted all the clutter and just put it into React. However, there is the same problem in React. When I change the "custom rate law" to "built in rate law" then there is no problem and the calcite reacts - but when I add the script file then nothing happens and the model totally ignores the calcite as if it is not there. (It may not be neccesary to assign such a complex rate law to calcite but I would like to sort out the principle - how to let a mineral dissolve with different rate laws under different pH conditions). I use GWB 8.012. Thanks so much for your help. Regards Johan Example of calcite dissolution.rea ratelaw_calcite.txt
  8. Hi I am trying to model calcite dissolution under both neutral and acid conditions as the model start with the former and end with the latter. However, GWB totally ignores dissolution when I assign a script to the model (calcite reacted = 0). The script is given below. Is my script wrong that GWB ignores it? I also assigned a rate const and a surface area in the interface for the neutral conditions. I assumed that neutral/acid conditions change at 6.3. Thanks in advance. Regards Johan IF pH > 6.3 THEN 20 ELSE 40 20: rate = rate_const * surface * (1 - Q/K) GOTO 60 40: rate = 3.235936569E+05 * rate_const * surface * (1 - Q/K) * activity("H+")^powerD(1) 60: RETURN rate
  9. Hi Brian Will you please show me how to add such a fake mineral and aqueous specie in order to allow for increase in water content? Although the dissolution of the mineral wont react with other species, wont it influence system parameters or thermodynamics of the system? If I could change the water content over time it is something that I will be able to frequently use in my modelling. Your help is highly appreciated. Regards Johan
  10. It would probably work better if I do it in X2t because in X1t flow can only be in one dimension?
  11. Hi Is it possible to increase the water content in X1t over the model time (node per node)? In the model is an unsaturated zone with an underlying saturated sone and I want to simulate a rising waterlevel. As I understand the "porosity" in "medium properties" needs to increase over time. The unsat zone has an initial water content of 0.1 and this must increase to 0.3 over time. If not in GWB, is it possible to write such a function/script outside GWB? Regards Johan
  12. Hi Brian I have a column test with Cu material (mostly bornite, very little chalcopyrite) I want to model. I have tried the modelling but it still doesnt yield satisfactory results. Usually I have no problem to simulate columns with pyrite but this one is very different and I want to figure out why the SO4 production is so different. There was some lag time (8weeks) before SO4 was suddenly produced (at a significant rate) which I found very suprising. I thought it might have something to do with the mineral kinetics but I am going to send the sample for SEM to see if it could recognise any secondary mineral phases - I think this might help with understanding the results. Has anyone else experience with columns tests on Cu material? Kind Regards Johan
  13. In the end I let bornite dissolution generate the superficial CuS(aq) specie (instead of Cu++) in the database and just let CuS(aq) decompose (using redox kinetic)according to the kinetic rate of covellite. It is a shortcut and I hope it is "legal".
  14. Hi Brian Thanks for the detailed reply! That is why I am using GWB. Anyway, I will try your recommondation and will have a look at the examples. I will let you know whether I came right. Thanks for your help! Regards Johan
  15. My problem is similiar to https://www.rockware.com/forum/index.php?showtopic=1099