Abstract
The variation of DO (dissolved oxygen), pH and ORP in the course of Fe(OH)2 oxidation, the yields of Fe3O4 determined by measuring the concentrations of Fe(II) and total Fe ions in the suspension and the settling velocity of final oxidation products were studied.
Completion of Fe(II) oxidation was detected by measuring the DO concentration or ORP in alkaline suspensions. During the oxidation, DO value was not detected and the rate of Fe(II) oxidation was shown by the product of KLa (oxygen transfer coefficient) by the saturated concentration of oxygen in the suspension.
The initial pH suitable for Fe3O4 formation was 11.5-12.5 at 40°C or lower and 11.5-13 at 60°C or higher, whereas the settling velocity of the final products became faster as the initial pH was lower.
