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Everything posted by forrie

  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. 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
  3. 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
  4. 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
  5. Hi Brian Thank so much for your help! Regards Johan
  6. 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
  7. 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
  8. 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
  9. It would probably work better if I do it in X2t because in X1t flow can only be in one dimension?
  10. 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
  11. 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
  12. 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".
  13. 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
  14. My problem is similiar to https://www.rockware.com/forum/index.php?showtopic=1099
  15. Hi Please help - this is urgent How do I force all Cu2++ from kinetic bornite dissolution to form kinetic CuS (covellite - ALTHOUGH IT MAY BE UNDERSATURATED) and Cu+ must go into solution. The covellite must then dissolute kinetically into Cu++ and SO4--. I want Covellite also as kinetic mineral so I dont want to swap Cu++ with covellite in the basis pane. While I am writing here I am thinking prehaps to specify two new (artificial) minerals in the database - one containing the Cu+ part of the bornite and the other one the Cu++ part and then give them seperate kinetic rates. But now I think this will not work because I want to state a kinetic rate for the production of the Cu++ from Bornite dissolution and a separte rate for Cu++ production from the formed covellite. Regards Johan
  16. forrie

    Mixing in GSS

    Tom, thanks a lot. GSS is really nice to work with your chemical data. Regards Johan
  17. forrie

    Mixing in GSS

    I have only downloadedinstalled the latest patch 808
  18. forrie

    Mixing in GSS

    Hi In the patch description the following: "We have released GWB 8.0.7, which addresses the following issues: •In GSS, allow mixing of samples in arbitrary mass ratios." First problem: Ive downloaded the patch but I cant see where to change the mixing ratios in GSS. (One can still mix it yourself in excel but it would be nice if it can be done automatically). Second problem: why dont GSS mix alkalinities? Help will be appreciated Regards J
  19. hi Tom, Thanks for the upgrade link you sent, however, I still cant plot my scatter data in Gtplot 8.0.2. The data works perfectly in GWB 7. "Time" "SO4--" "Sulfur" "Ca++" 7.00 2791 931.52 435.00 14.00 1827 609.78 377.00 21.00 1285 428.88 308.00 28.00 961.00 320.74 285.00 35.00 860.00 287.03 254.00 42.00 767.00 255.99 242.00 black black black black yield yield yield circle Kind Regards Johan
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