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Kinetic Calcite


H Kerfoot
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I am trying to model the kinetic dissolution of limestone using Kinetic Calcite. The specific command I am using is:

 

75 gram of Calcite by kinetic rate law

Rate law = "rate_con * surface * (0.30*molality('CO3--')/Ksp - molality('Ca++'))"

Rate constant = 2.7e-6 mol/cm2 sec

Specific surface area = 3.37 cm2/g

 

REACT runs for some time and seems to end normally. However, the printd output (View Results) only contains information for Step 0. (See below)

 

I am wondering what is causing this - This is the first time I have used the kinetic part of REACT, so please let me know if I did something dumb so that i can correct.

output and input below (in that order) --

 

OUTPUT

Step # 0 Xi = 0.0000

Time = 0 secs (0 days)

 

Temperature = 25.0 C Pressure = 1.013 bars

pH = 6.250

Ionic strength = 0.002195

Activity of water = 0.999937

Solvent mass = 1.000000 kg

Solution mass = 1.000104 kg

Solution density = 1.013 g/cm3

Chlorinity = 0.001790 molal

Dissolved solids = 104 mg/kg sol'n

Rock mass = 0.075000 kg

Carbonate alkalinity= 0.54 mg/kg as CaCO3

 

moles moles grams cm3

Reactants remaining reacted reacted reacted

----------------------------------------------------------------------------

Calcite 0.7493 0.0000 0.0000 0.0000

 

Kinetic rate const. sp. surface net surface rxn rate

mineral rxns (mol/cm2 s) area (cm2/g) area (cm2) (mol/kg sec)

----------------------------------------------------------------------------

Calcite 2.000e-006 3.370 252.7 1.#IO

 

No minerals in system.

 

Aqueous species molality mg/kg sol'n act. coef. log act.

---------------------------------------------------------------------------

Cl- 0.001787 63.34 0.9490 -2.7706

Na+ 0.0009999 22.99 0.9498 -3.0224

Ca++ 0.0003970 15.91 0.8180 -3.4884

CO2(aq) 1.341e-005 0.5900 1.0000 -4.8726

HCO3- 1.080e-005 0.6591 0.9501 -4.9886

CaCl+ 2.906e-006 0.2195 0.9498 -5.5591

H+ 5.900e-007 0.0005946 0.9531 -6.2500

CaHCO3+ 5.847e-008 0.005910 0.9506 -7.2551

NaCl 4.051e-008 0.002367 1.0000 -7.3925

OH- 1.931e-008 0.0003283 0.9494 -7.7368

NaHCO3 1.312e-008 0.001102 1.0000 -7.8820

(only species > 1e-8 molal listed)

 

Mineral saturation states

log Q/K log Q/K

----------------------------------------------------------------

(only minerals with log Q/K > -3 listed)

 

Gases fugacity log fug.

-----------------------------------------------

Steam 0.03131 -1.504

CO2(g) 0.0003800 -3.420

 

In fluid Sorbed Kd

Original basis total moles moles mg/kg moles mg/kg L/kg

-------------------------------------------------------------------------------

Ca++ 0.000400 0.000400 16.0

Cl- 0.00179 0.00179 63.4

H+ 1.40e-005 1.40e-005 0.0141

H2O 55.5 55.5 1.00e+006

HCO3- 2.43e-005 2.43e-005 1.48

Na+ 0.00100 0.00100 23.0

 

Elemental composition In fluid Sorbed

total moles moles mg/kg moles mg/kg

-------------------------------------------------------------------------------

Calcium 0.0004000 0.0004000 16.03

Carbon 2.429e-005 2.429e-005 0.2917

Chlorine 0.001790 0.001790 63.44

Hydrogen 111.0 111.0 1.119e+005

Oxygen 55.51 55.51 8.880e+005

Sodium 0.001000 0.001000 22.99

 

INPUT:

 

 

Options: Debye-Huckel

 

Reaction runs from 0 days to 1 days

Temperature is 25 C

Thermo dataset: c:\program files\gwb\gtdata\thermo.dat

Basis is:

H2O 1 free kg

CO2(g) (swapped for HCO3-) .00038 fugacity

Na+ .001 molarity

Cl- .001 molarity (charge balance species)

Ca++ 4e-4 molarity

H+ 6.25 pH

Reactants:

75 gram of Calcite by kinetic rate law

Rate law = "rate_con * surface * (0.30*molality('CO3--')/Ksp - molality('Ca++'))"

Rate constant = -2e-6 mol/cm2 sec

Specific surface area = 3.37 cm2/g

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Rate law = "rate_con * surface * (0.30*molality('CO3--')/Ksp - molality('Ca++'))"

 

Hi Henry:

 

In your custom rate law, try changing 'Ksp' to 'K', as React will only recognize the latter as a valid parameter for the equilibrium constant.

 

If it still doesn't work, please attach the entire React script, so I'm sure to compare apples to apples..

 

Best regards,

 

Tom Meuzelaar

RockWare, Inc.

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