# pH buffering by silicate reactions in the Koenigstein uranium mine SOLUTION_SPECIES H2O + 0.01e- = H2O-0.01; log_k -9 PHASES Adularia # log_k from llnl.dat = phreeqc.dat -2.0 KAlSi3O8 + 8H2O = K+ + Al(OH)4- + 3H4SiO4; log_k -22.573; delta_h 30.82 kcal RATES Pyrite # rates from data compiled by # Williamson and Rimstidt 1994, GCA 58, 5443 -start 1 A = 0.3 * m0 # surface area in m2/dm3 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") * 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 Goethite # estimated from Zinder et al., 1986, GCA 50, 1861, data without organic cplx # r_Goethite = 10^-11.0 * [H+]^0.45 mol/m2/s -start 1 A0 = 2000 * m0 # surface area in m2/mol Goethite 2 SS = (1 - SR("Goethite")/1) 20 moles = A0 * (m/m0)^0.67 * 10^-11 * act("H+")^0.45 * SS * time 50 if moles < 0 then moles = moles / 10 # 10 times smaller precipitation rate 60 save moles -end Kaolinite # Rate from Sverdrup and Warfvinge, 1995, Am Mineral. 31, 485. # r in 1/6 kmol kaol/m2/s (is 1 kmol H+/m2/s) -start 10 A = 3150 * m0 # m2 for 10 m2/g 20 f_Al = 1 + tot("Al")/4e-6 30 r = 10^-15.1 * act("H+")^0.7 * f_Al^-0.4 + 10^-17.6 * f_Al^-0.2 40 moles = A * r/6 * 1e3 * (m/m0)^0.67 * (1 - SR("Kaolinite")) * time 50 if moles < 0 then moles = moles / 10 # 10 times smaller precipitation rate 60 save moles -end Adularia # K-feldspar in phreeqc.dat # Rate from Sverdrup and Warfvinge, 1995, Am Mineral. 31, 485. # r in kmol/m2/s at 8 oC -start 10 A = 111 * m0 # m2 for 0.4 m2/g K-fsp 20 f_Al = 1 + tot("Al")/4e-6 30 r = 10^-14.7 * act("H+")^0.5 * f_Al^-0.4 + 10^-17.5 * f_Al^-0.14 40 moles = A * r * 1e3 * (m/m0)^0.67 * (1 - SR("Adularia")) * time 50 if moles < 0 then moles = moles / 10 # 10 times smaller precipitation rate 60 save moles -end END SOLUTION 1 # Mine water from Bain et al., 2001 -temp 10; pH 2.3 Na 23.8; K 0.1; Mg 2.0; Ca 11.6 C 1.7e-4; Cl 13.0; P 0.08; S(6) 52.8 charge Al 6.5; Cd 0.01; Fe(3) 10.7; Fe(2) 0.27; U(6) 0.18; Zn 1.5; KINETICS 1 Pyrite; m0 0.1 Goethite; m0 0.02 # Kaolinite; m0 1.27 # 5% kaol = 400 g/L / (M = 322g/mol) # Adularia; m0 1.44 # 5% Kfsp = 400 g/L / (M = 278 g/mol) -step 9e8 in 100 -bad 1000 INCREMENTAL_REACTIONS true EQUILIBRIUM_PHASES 1; Cristobalite; PRINT; -reset false; -status false #SELECTED_OUTPUT # -file e:\p\pg.csv; -reset false USER_GRAPH -head time K Adul Kaol Go Pyr pH -axis_scale y_axis -9 3 -start 10 graph_x sim_time/(24*3600*365) 20 graph_y tot("K"), SI("Adularia"), SI("Kaolinite"), SI("Goethite"), SI("Pyrite") 30 graph_sy -la("H+") -end END