Siderite (FeCO 3): Its dissolution and interaction with stannic oxide in aqueous suspensions

Abstract

The dissolution rates of a magnesium-rich siderite and an iron-rich magnesite were measured as a function of pH. Electrophoretic measurements were performed on siderite (IEP = pH 7.9), stannic oxide (IEP = pH 4.5), as well as on stannic oxide suspended in solutions of Fe(II), Fe (III), Mg(II) and carbonate. Whilst MG(II) and carbonate had little effect on the isoelectric point (IEP) of stannic oxide, FE(II) and FE(III) adsorbed strongly, shifting the IEP to considerably higher pH values. Electrophoretic mobilities were also measured on stannic oxide particles suspended in filtrates derived directly from siderite suspensions. Under certain circumstances, the surfaces of stannic oxide and siderite became indistinguishable from each other with respect to measured zeta potentials. The significance of these results for selective flotation of cassiterite from siderite is discussed.