kinectic of galena and cerussite in acid ph

[Scarlet]

hello sir david,
Please, I want to know if my execution of kinetics to find the index of saturation of galena and cerussite in acid ph are right.
thank you
 
RATES
    Galena
-start
10 k = PARM(1)
20 n = PARM(2)
30 ph = PARM(3)
40 lograte = LOG k-n*ph
50 moles = (10^lograte)*TIME
60 SAVE moles
-end

KINETICS 1
Galena
    -formula  PbS  1
    -m        0.001
    -m0       0.0019
    -parms    2.34e-07 1 4
    -tol      1e-08
-steps       977600000 in 31 steps # seconds
-step_divide 1
-runge_kutta 6
-bad_step_max 100

INCREMENTAL_REACTIONS True

SOLUTION 2
    temp      25
    pH        2
    pe        2
    redox     pe
    units     mg/l
    density   1
    As        43.89
    B         0.05595
    C(4)      82.82
    Ca        28.8
    Cd        0
    Cl        943.12
    K         33.12
    Li        0.01974
    Mg        133.9
    Na        1148.84
    Pb        2.2e-05
    Sr        0.768
    Zn        0.002939
    -water    1 # kg
USER_GRAPH 1
    -headings               Years Pb
    -axis_titles            "Years" "Molality Pb" ""
    -initial_solutions      false
    -connect_simulations    true
    -plot_concentration_vs  x
  -start
10 GRAPH_X TOTAL_TIME/3.1536e7
20 GRAPH_Y TOT("Pb")*207.2*1000*1000
  -end
    -active                 true


USER_GRAPH 3
    -headings               Years Galena
    -axis_titles            "Years" "Saturation Index" ""
    -initial_solutions      false
    -connect_simulations    true
    -plot_concentration_vs  x
  -start
10 GRAPH_X TOTAL_TIME/3.1536e7
20 GRAPH_Y SI("Galena")
  -end
    -active                 true
USER_GRAPH 4
    -headings               Years Cerussite
    -axis_titles            "Years" "Saturation Index" ""
    -initial_solutions      false
    -connect_simulations    true
    -plot_concentration_vs  x
  -start
10 GRAPH_X TOTAL_TIME/3.1536e7
20 GRAPH_Y SI("Cerussite")
  -end
    -active                 true
USER_GRAPH 5
    -headings               Years cerussite Galena
    -axis_titles            "Years" "Saturation Index" ""
    -initial_solutions      false
    -connect_simulations    true
    -plot_concentration_vs  x
  -start
10 GRAPH_X TOTAL_TIME/3.1536e7
20 GRAPH_Y SI("Cerussite"),SI("Galena")
  -end
    -active                 true
END

[dlparkhurst]

I have no idea whether your calculations are "right".

The rate that you have is very slow. You have removed oxygen from your rate definition, but I expect that the availability of oxygen is a critical factor in the rate of galena dissolution.

[Scarlet]

thank you for your reply.
I tried to follow the dissolution of galena in the pit lake of an old mine of lead.
so I tried to take a kinetic equation and apply it directly