第一鉄イオンによる二酸化マンガンの還元溶解
1981 年 97 巻 1118 号 p. 267-271
詳細
1981 年 97 巻 1118 号 p. 267-271
The reductive dissolution of manganese dioxide in acidic aqueous solutions containing ferrous salts was studied from both thermodynamic and kinetic points of view. A rotating disc technique was employed in this study. This reaction is thought to be expressed as:
MnO2+2Fe2++4H+=Mn2++2Fe3++2H2O
or,
MnO2+2Fe2++4H2O= Mn2++2Fe (OH) 3+2H+.
It was, observed that the reaction rates were of 0.85th orderwith respects to ferrous ion concentration, while no distinct dependency was observed for acid concentration. The activation energies for the reductive dissolution reactions were 14.0 kJ/mol in H2SO4 solution and 19.3 kJ/mol in HCl solution. The overall reaction was thought to be controlled by a mass transfer of ferrous ions through the boundary layer between the acidic solution and the surface of the manganese dioxide.
Leaching experiments were carried out by applying this reaction to the dissolution for theparticulate samples of low grade manganese dioxide ore and manganiferrous nodules from deep ocean. High recoveries of manganous ions in the leach solution were achieved at room temperature after a very short retention time.
