On the thermal decomposition of dolomite. IV.thermogravimetric investigation of the dolomite decomposition

Abstract

The thermal decomposition of dolomite at various constant temperatures and carbon dioxide pressures has been investigated by the ‘loss‐of‐weight method.’ Depending on these conditions, dolomite can be decomposed either stepwise to magnesium oxide and calcium carbonate (‘half‐burnt dolomite’) with subsequent dissociation of calcium carbonate, or in a single stage to both magnesium oxide and calcium oxide. It is most significant that partial decomposition is independent of the carbon dioxide pressure occurring within the same narrow temperature range, about 680°. If the ambient carbon dioxide pressure is lowered below the dissociation pressure of calcite corresponding to this temperature, then decomposition curves are shifted to lower temperatures. The second stage of the step‐wise decomposition occurs at increasingly higher temperatures with increased carbon dioxide pressure. However, complete decomposition becomes progressively more difficult owing to remaining calcium carbonate. A reaction mechanism of the thermal decomposition of dolomite is propounded based on these thermogravimetric results in conjunction with thermodynamic calculations and X‐ray studies.

Dolomía y dolomita: un abordaje desde las perspectivas geológica, cerámica y refractaria

“…Se ha sugerido que en la etapa inicial, tanto la calcia como la magnesia son formadas. Se ha propuesto que la primer etapa de la descomposición de la dolomita en atmósfera de CO2 ocurre por la formación de una magnesita inestable la cual se descompone inmediatamente a magnesia y calcita (dolomita a "medio calcinar", "half burnt dolomite") (Haul y Markus, 1952). La segunda etapa de descomposición de la dolomita, involucra la descomposición reversible de la calcita a calcia, la cual es altamente reactiva.…”

A Kinetic Study of Thermal Decomposition of Limestone UsingIn SituHigh TemperatureX‐Ray Powder Diffraction

“…4 it is clear that the decomposition occurs by a single step: dolomite dissociates simultaneously into CaO and MgO without involving the two stage process where MgO is first accompanied by the formation of calcite, and later by the growth of CaO generated owing to the calcite decomposition with the evolution of CO 2 . 26,27 In Fig. 5b the a-t curves belonging to the dolomite thermal decomposition for sample A are reported.…”