Reaction of α-Fe2O3 (hematite) with potassium carbonate at elevated temperatures

The kinetics of the reaction between α-Fe2O3 and K2CO3 have been investigated over the temperature range 600 to 800 °C, and the phase composition of the products has been determined. The reaction follows the rate law α = 1 - exp (-kτn). At molar ratios K : Fe 1, KFeO2 is the only product. At K : Fe 1, initially formed KFeO2 reacts with hematite to yield K2Fe4O7. The latter phase has been assigned a cubic structure with a = 1.681 ± 0.003 nm. based on X-ray powder diffraction patterns and Mossbauer spectra, the structure of K2Fe4O7 is proposed to be a cubic close-packed array of oxygen atoms, part of these being replaced by potassium atoms, with Fe atoms occupying the octahedral interstices.