Decomposition of Dolomite Monitored by Neutron Thermodiffractometry

Abstract

Dolomite powder from Coín (Spain) was heated in air at a constant rate of 2°C/min to 1000°C, while neutron diffraction patterns were collected every 150 s. Rietveld refinement was applied and raw intensity data were used to monitor decomposition. The full process happened in two stages: dolomite decomposition to give calcite and periclase, and calcite breakup. The first stage activation energy was 47 kcal·mol −1 from fitting to a contracting sphere model. The dolomite mean thermal expansion coefficients were (6.7 ± 0.4) × 10 −6 and (2.7 ± 0.2) × 10 −5 K −1 along the a and c axes, respectively. Changes in the Ca–O and Mg–O bond distances were also measured.