Re: arsenopyrite oxidation with Fe+3 modelling with PHREEQC

["David L Parkhurst" <dlpark@xxxxxxxx>]

I don't know exactly how you want to model this reaction. Below is an input
file that takes pure water, equilibrates with arsenopyrite, and then adds a
quantity of FeCl3 and re-equilibrates with arsenopyrite. I used llnl.dat
because it had the arsenopyrite phase in the database; however, you can
make the same calculation with wateq4f.dat if you define arsenopyrite in a
PHASES data block in the input file. The calculation assumes redox
equilibrium for iron.

David

SOLUTION 1
EQUILIBRIUM_PHASES 1
    Arsenopyrite 0 10

END
USE solution 1
USE equilibrium_phases 1
REACTION
      FeCl3 1.0
      .001 moles
END

David Parkhurst (dlpark@xxxxxxxx)
U.S. Geological Survey
Box 25046, MS 413
Denver Federal Center
Denver, CO 80225


                                                                                                                             
                      "Ricardo                                                                                               
                      Perobelli Borba"         To:      <dlpark@xxxxxxxx>                                                    
                      <borba@xxxxxxxxx         cc:                                                                           
In-Reply-To: <000a01c1b246$93528c40$2bc86a8f@xxxx>
                      mp.br>                   Subject: arsenopyrite oxidation with Fe+3 modelling with PHREEQC              
                                                                                                                             
                      02/10/02 08:49                                                                                         
                      AM                                                                                                     
                      Please respond                                                                                         
                      to "Ricardo                                                                                            
                      Perobelli Borba"                                                                                       
                                                                                                                             
                                                                                                                             



Dear Dr. David Parkhurst

I want use the PHREEQC to forward modelling the oxidation of arsenopyrite
by Fe+3, to simulate bacterial action in oxidation process, with this
equation:  FeAsS + 13 Fe+3  + 8H2O = 14Fe+2 + HSO4-2 + SO4-2 + 15H+, but I
don´t know how introduce the Fe3+ in the WATEQ4Fdatabase file, without
cause any trouble in the program calculations, to use it in the REACTION
block, could you have some sugestion to solve this problem?


Thanks in for your attention

Ricardo Perobelli Borba
Instituto de Geociências - Unicamp
Brazil