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Geochemist's Workbench Support Forum


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About SebFuchs

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  1. Hello GWB experts, I am wondering if there is an easy way to calculate the (maximum possible) solubility of a mineral / metal in a fluid along a reaction path in the REACT program. Assuming an reaction path of a cooling fluid (e.g. from 250 °C to 25 °C) with different dissolved metal species (e.g., Fe, Na, Ca ....). REACT show nicely the actual concentrations of the different aqueous species, as well the amount of minerals that precipiate once saturation is reached. Is it possible to calculate and show the max. solubility of metal / mineral in this context (e.g. max solubilty of Fe at temperature)? Many thanks in advance, Sebastian
  2. Dear GWB - Team, I use the REACT module to study the precipitation of minerals when a hot hydrothermal fluid is mixed with cold seawater (simple titration model, only dump command is on). I can read from the plot (Fig. 1) that sphalerite and gold start to precipitate somewhat above 100°C. With further cooling the mineral concentrations slightly decrease again, which means to me that the minerals (re-)dissolve back into the fluid again (please correct me if I am wrong). The concentrations of these metals in the fluid, however, remain low (Fig. 2) and the Saturation Index (Fig. 3) remain high showing that there is no re-dissolution of the minerals into the fluid. This does not make sense to me. Is there a fundamental problem in the calculation / model or am I reading Figure 1 in a wrong way? Best greets, Sebastian
  3. Hi to all, I would like to ask you for some advices in choosing the right reaction paths models in REACT. I'd like to calculate a mixing model of (1) hot metal-bearing fluid (small volume, low pH, supersaturated with some mineral phase) with a (2) cold, almost pure fluid (high pH, high volume). I want to find out the amount of metals that can be removed and precipitated as minerals from hot fluids (should be mainly due to changes in T and pH) when it starts to mix with the cold fluid. I want neglect any supersaturated minerals that might be present in the initial fluids. Once the minerals precipitated as a result of the mixing of the fluids, they should be prevented from re-dissolving into the liquida at any further step of the fluid mixing. In REACT I played around with the "flow-through" and "flash" models (with "dump" option on). The results of both look quite different. Could you please give a recommendation, which model might be the best in order to describe the mineral precipitation from one fluid as a result of the 2-fluid mixing. Many thanks in advance, Sebastian
  4. Hi Brian, many thanks for your help. To disable redox coupling helped to set two set both initial values for SO4 and H2S. My analytical instrument provides elemental concentrations - that's why I used the "as" function. I still did not find a solution why gold is not the list of minerals (for mineral saturation) in GSS, as it is in SpecE8 and REACT. The reason is O2. In SpecE8 I use H2(aq) swapped for initial O2, in GSS it is only possible to add H2(aq) as basis species. Only if I add O2 to the system in GSS then I will have gold in the list. I am wondering, if there is a workaround in GSS, that I do not to provide values for O2. Cheers, Sebastian
  5. Hi Brian, many thanks for your help. I removed the entry "new mineral" and all the duplicates and it solved the problem. I have 2 more questions to you, regarding the database and SpecE8 / GSS. I want to calculate the metal speciations and mineral saturation states (esp. for gold). 1) Both SpecE8 and GSS calculate at the fixed pressures defined in the database. In the thermo.tdat file the pressure for 250 °C is 39.776 bars . Is it possible to do the calculation at a specific pressure, e.g., 50 bars at 250°C, without modifying the whole database? 2) I have 2 sulphur species SO4 and H2S as input values. In GSS I used SO4-- as basis species and change it SO4, and HS- to H2S(aq). When I used SpecE8 I was only able to add 1 sulphur species (e.g., SO4-- as H2S(aq)). When I did the calculations with GSS, the program did not calculate the saturation state for gold. In SpecE8 (using only H2S(aq)), however it calculated the saturation state for gold. In the database gold is defined as: Gold + H(+) + 0.25 O2 = Au(+) + 0.5 H2O Do you know why it is not possible to calculate the saturation state of gold using 2 sulphur species in GSS (it is also not possible when I am transferring the data to SpecE8)? Many thanks, Sebastian
  6. Hi Brian, I am using GWB 11. I sent you my database file right now by email. Cheers, Sebastian
  7. Hi, I was working on my thermo.dat this morning and added some new aqueous and mineral species. After saving the file and closing TEdit programm, I am not able to open thermo.dat file anymore. The program closes with the message: "TEdit is not working". I tried to restart the computer and open the file using ACT but nothing is working. I was only able to open an older backup of the file that made weeks ago. So I guess something went wrong when saved the file. Can you please help me to solve the problem? The file is too large to attach (600KB) but I can email it. Many thanks in advance. Sebastian