Reduction leaching of rare earth from ion-adsorption type rare earths ore with ferrous sulfate

Eh-pH diagram of cerium Line (1): Ce4++e−↔Ce3+, ϕ1=1.61 V; Line (2): Ce(OH)4+H++ e−↔ Ce(OH)2+H2O, ϕ2=0.0497-0.0592pH (V); Line (3): Ce(OH)4+ 4H++e−↔Ce3++4H2O, ϕ2=1.68-0.23pH (V); Line (4): Ce(OH)4+ 4H+↔Ce4++4H2O, pH=0.3; Line (5): Ce3++3OH−↔Ce(OH)2, pH=6.7; Line (6): 2H++2e−↔H2↑, ϕ6=−0.0592pH (V); Line (7): O2+4H++4e−↔2H2O, ϕ7=1.229-0.0592pH (V)