Physiochemical Restrictions of Mineral Zoning of Sediment-Hosted Stratiform Copper Deposit in SW China

Table 2

Chemical reactions and Eh-pH expressions.

Chemical reactions	pH-Eh expressions
	523 K	473 K	423 K	373 K
(1) 2H2O = O2 + 4H^+ + 4e	1.129 − 0.104pH	1.142 − 0.094pH	1.166 − 0.084pH	1.167 − 0.074pH
(2) H2 = 2H^+ + 2e	−0.104pH	−0.094pH	−0.084pH	−0.074pH
(3) = + H^+	pH = 5.40	pH = 4.56	pH = 3.73	pH = 2.98
(4) S + 4H2O = + 7H^+ + 6e	0.367 − 0.121pH	0.340 − 0.110pH	0.33 − 0.098pH	0.288 − 0.086pH
(5) S + 4H2O = + 8H^+ + 6e	0.462 − 0.138pH	0.411 − 0.125pH	0.38 − 0.112pH	0.325 − 0.099pH
(6) H2S = S + 2H^+ + 2e	0.233 − 0.104pH	0.220 − 0.094pH	0.211 − 0.084pH	0.205 − 0.074pH
(7) H2S = HS^− + H^+	pH = 7.61	pH = 7.09	pH = 6.71	pH = 6.57
(8) HS^− + 4H2O = + 9H^+ + 8e	0.305 − 0.117pH	0.280 − 0.106pH	0.268 − 0.094pH	0.235 − 0.083pH
(9) HS^− = S^2− + H^+	pH = 11.43	pH = 11.28	pH = 11.30	pH = 11.68
(10) S^2− + 4H2O = + 8H^+ + 8e	0.157 − 0.104pH	0.148 − 0.094pH	0.149 − 0.084pH	0.127 − 0.074pH
(11) 3Fe + 4H2O = Fe3O4 + 8H^+ + 8e	−0.085 − 0.104pH	−0.903 − 0.094pH	−0.091 − 0.084pH	−0.112 − 0.074pH
(12) 2Fe3O4 + H2O = 3Fe2O3 + 2H^+ + 2e	0.24 − 0.104pH	0.22 − 0.094pH	0.21 − 0.084pH	0.17 − 0.074pH
(13) Fe^2+ = Fe^3+ + e	0.95	0.94	0.90	0.86
(14) 2Fe^2+ + 3H2O = Fe2O3 + 6H^+ + 2e	1.602 − 0.341pH	1.352 − 0.282pH	1.282 − 0.252pH	1.142 − 0.222pH
(15) 3Fe^2+ + 4H2O = Fe3O4 + 8H^+ + 2e	2.258 − 0.456pH	1.918 − 0.376pH	1.818 − 0.336pH	1.628 − 0.296pH
(16) 2Fe^3+ + 3H2O = Fe2O3 + 6H^+	pH = 1.18	pH = 1.11	pH = 1.34	pH = 1.3
(17) 2Cu + 4H2O = Cu2O + 2H^+ + 2e	0.46 − 0.104pH	0.45 − 0.094pH	0.46 − 0.084pH	0.44 − 0.074pH
(18) Cu2O + H2O = 2CuO + 2H^+ + 2e	0.67 − 0.104pH	0.65 − 0.094pH	0.62 − 0.084pH	0.62 − 0.074pH
(19) Cu^+ = Cu^2+ + e	0.37	0.32	0.27	0.22
(20) Cu^+ + e = Cu	−0.30	−0.36	−0.41	−0.45
(21) 2Cu^+ + H2O = Cu2O + 2H^+	pH = 9.53	pH = 9.05	pH = 8.65	pH = 7.86
(22) Cu^2+ + H2O = CuO + 2H^+	pH = 6.23	pH = 6.32	pH = 6.58	pH = 6.60
(23) 2Cu^2+ + H2O = Cu2O + 2H^+ + 2e	0.622 − 0.104pH	0.532 − 0.094pH	0.462 − 0.084pH	0.362 − 0.074pH
(24) Fe^2+ + 2H2S = FeS2 + 4H^+ + 2e
(25) Fe^2+ + S2 + 2e = FeS2
(26) Cu^+ + = Cu^2+ + + e	−0.63	−0.67	−0.72	−0.77
(27) 2FeS2 + Cu^2+ + 4H^+ + 4e = CuFeS2 + Fe^2+ + 2H2S	−0.16 + 0.104pH	−0.15 + 0.094pH	−0.14 + 0.084pH	−0.14 + 0.074pH
(28) 2CuFeS2 + 3Cu^2+ = Cu5FeS4 + Fe^2+ + 4e	−0.59	−0.59	−0.59	−0.6
(29) 2Cu^+ + S^2− = Cu2S
(30) 15Cu2S + 2Fe3O4 + 7H^+ + 9HS^− = 6Cu5FeS4 + 8H2O + 2e	−4.86 + 0.364pH	−4.34 + 0.329pH	−3.96 + 0.294pH	−2.1 + 0.259pH