# estimate A of pyrite to reduce 22 mol/L/yr
# volume = 0.1 * 1 = 0.1 m3
# 0.1m3 * 30% of 0.3  = 9 L water
# 0.1m3 * 2 ton/m3 * 0.04 / 119.85 / 9 = 7.4 mol pyr/L = m.  m * 2 = m0 = 14.8 mol/L
# 22 mol O2 * 24/0.2 = 2640 L air
# Note the increase in rate when pH < 3 and Fe+3 is important oxidator
RATES
 Pyrite  # rates from data compiled by Williamson and Rimstidt 1994, GCA 58, 5443
 -start
  1 A = 0.0073 * m0 # initial surface area in m2 indicates 2 cm size crystals
 10 if SI("Pyrite")>0 then goto 100
 20 fH = mol("H+")
 30 fFe2 = (1 + tot("Fe(2)")/1e-6)
 40 if mol("O2") < 1e-6 then goto 80
# rate with oxygen...
 50 rO2 = 10^-8.19 * mol("O2")^0.5 * fH^-0.11
# rate with oxygen and Fe3+...
 60 rO2_Fe3 = 6.3e-4 * tot("Fe(3)")^0.92 * fFe2^-0.43
 70 goto 90
 80 rem
# rate with Fe3+ without oxygen, and for pH < 3
 81 rFe3 = 1.9e-6 * tot("Fe(3)")^0.28 * fFe2^-0.52 * fH^-0.3
 90 rate = A * (m/m0)^0.67 * (rO2 + rO2_Fe3 + rFe3) * (1 - SR("Pyrite"))
 100 save rate * time
 -end

SOLUTION_SPECIES  # make N2 the only N species...
 2NO3- + 12H+ + 10e- = N2 + 6H2O; log_k 500 #207.080
SOLUTION 1
 pH 7 charge;        pe 14 O2(g) -1.0878
 Ca 1 Calcite;       C(4) 1 CO2(g) -2.6021
 Fe 1e-3 Goethite 2; N 1.3 N2(g) -0.0382

PHASES
JarositeH		337
	(H3O)Fe3(SO4)2(OH)6 + 5H+ = 3Fe+3 + 2SO4-2 + 7H2O
	log_k		-5.390
	delta_h -55.150 kcal
EQUILIBRIUM_PHASES 1
 Goethite 2 100; JarositeH 0 0
GAS_PHASE 1
 -fixed_pressure  # default 1 atm
 -volume 2640
 O2(g) 0.2; N2(g) 0.8
KINETICS 1
  Pyrite; -m0 14.8; -m 7.4; -step 3.05e7 0.1e7
INCREMENTAL_REACTIONS true
END