An Investigation of the Mechanism Magnetite Precipitation Using Ammonium Carbonate

Abstract

The purpose of this study is to determine the phase composition of iron oxide compounds formed during precipitation by ammonium carbonate hydrolysis products, to establish the magnetite formation regions and the kinetic characteristics of the reaction formation Fe3O4. Characterization by X-ray diffraction (XRD) indicated that magnetite is formed in a solution of ferrous sulphate during the hydrolysis of ammonium carbonate. It has a homogeneous phase composition and a cubic crystal structure. Phase diagrams of the formation of the crystalline phase of magnetite, goethite and ferric hydroxide have been determined. It has been established that magnetite with a spinel structure is formed under controlled slow precipitation from ferrous sulphate with an ammonium carbonate solution. The calculation of the kinetic characteristics of the reactions of solid phase precipitation (a rate constant at different initial concentrations of ferrous sulphate, the order of the reaction) has shown that the process proceeds in two stages with the formation of an intermediate compound and its further oxidation. Moreover, the rate constant of oxidation is 0.654 L/min mol, and the rate constant of the first reaction is much higher – 1.645 L/min mol.