CPS reactivity

[mmhassan]

Hello Sir,

I am trying to model an abandoned mine where heavy metal is leaching into the groundwater. For the remediation, CPS injection will be performed.

I tried to script this way but it seems like it doesn't work properly.

Here,

1. I wanted to generate the initial solution by the existing mineral
2. Then inject the contaminant into the solution to make the initial solution contaminated
3. Finally, injected CPS to remediate

SOLUTION 1000
   units        mol/kgw
        temp             20.0
        pH                4.0     charge
   Cd             0.001                    
   Zn             0.1
   S(6)        1
END   

SOLUTION 1001
   units        mol/kgw
        temp             20.0
        pH                11.0     charge
   S(-2)        5
   Ca           1
END

SOLUTION 1-10
    temp            20                      
    pH              4.0 
         
EQUILIBRIUM_PHASES 1-10
   Quartz         0      26.7              
   Albite             0      6.4              
   Anorthite        0      0.89              
   Muscovite      0   3.8
   Annite      0   4
   Kaolinite      0   0.18
   Illite         0   0.08
   Hausmannite   0   2
   CO2(g)         -3.5
   
COPY SOLUTION 1000 0
END

TRANSPORT
    -cells                            10
    -lengths              0.1
    -shifts                           360
    -time_step                3600  # seconds
    -boundary_conditions     constant flux
    -diffusion_coefficient    1e-12
    -dispersivities           0.015
    -flow_direction           forward
    -punch_cells              1-10
   

EQUILIBRIUM_PHASES 1-10
   Sphalerite              0   0
   Greenockite      0   0
   ZnS(a)         0   0
   ZnO(a)         0   0
   Wurtzite              0   0
   Zn(OH)2-e      0   0
   Cd(OH)2         0   0
   Goethite              0   0
   Dolomite              0   0
   Calcite         0   0
   Hematite              0   0
   Magnetite              0   0
   Pyrolusite              0   0
   Gypsum         0   0   

COPY SOLUTION 1001 0
END

TRANSPORT
    -cells                            10
    -lengths              0.1
    -shifts                           360
    -time_step                3600  # seconds
    -boundary_conditions     constant flux
    -diffusion_coefficient    1e-12
    -dispersivities           0.015
    -flow_direction           forward
    -punch_cells      1-10
END

In the result before injecting the CPS, I wanted to see the initial solution chemistry, but the pH was not low enough, where in the field it is very low pH. Also, the mineral precipitation is different.

I need help to know that the approach is right or wrong?

Thanks in advance.

[dlparkhurst]

There are too many moving parts for me to help at this point.

Here is a simplified script for making acid mine water. You can add reactions as you see fit. In carbonate-hosted mines, dissolution of calcite and dolomite can lead to modified pH  and equilibrium with gypsum.

Code: [Select]

SOLUTION
EQUILIBRIUM_PHASES
Pyrite 0 1
Goethite 0 0
REACTION
O2 1
1e-6 1e-5 1e-3 1e-2 1e-1 1
INCREMENTAL_REACTIONS
USER_GRAPH 1
    -headings               S(6) pH
    -axis_titles            "Sulfate, mol/kgw" "pH" ""
    -axis_scale x_axis      auto auto auto auto log
    -initial_solutions      false
    -connect_simulations    true
    -plot_concentration_vs  x
  -start
10 GRAPH_X TOT("S(6)")
20 GRAPH_Y -LA("H+")
  -end
    -active                 true
END



[mmhassan]

Dear Sir,

Thank you so much for your reply.