The heat treatment and particle size effects in the thermal decomposition of dolomite for separation of constituents

Abstract

The effect of particle size and heat treatment on partial decomposition of dolomite for the extraction of calcite has been investigated. Isothermal firing trials varying the soaking period were performed for dolomite at temperatures between 1013-1033 K according to schedules derived from thermogravimetric analysis (TGA). Samples of dolomite representing three size fractions were used. It is shown that, the optimum heat treatment for reducing the residual MgO in extracted CaCO 3 and maximising the yield of CaCO 3 is accomplished at 1013 K. A soaking time of 160 min seems adequate. The highest degree of partial decomposition was obtained for the 150 µm size fraction of dolomite. A single processing cycle performed under the optimised conditions coupled with relatively short periods of hydration and re-carbonation (24 h, 15 min) yielded CaCO 3 with 7·5% MgO from a dolomite containing 23·6% MgO.

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

“…Dependiendo de las condiciones experimentales, la descomposición térmica puede proceder en una etapa endotérmica en aire (De Aza et al, 2002;Engler et al, 1989;Fang et al, 2011;Subagjo et al, 2017;Wiedemann y Bayer, 1987), nitrógeno (Bogahawatta et al, 2004;Wiedemann y Bayer, 1987), argón y helio (Smith et al, 1974), o en CO2 a una presión menor de 150 mm de Hg, de acuerdo a la ecuación (Otsuka, 1986;Santani et al, 2001) (Ecuación 3):…”

“…oxígeno; en CO2 se presenta una descomposición en tres etapas (Ptáček et al, 2021). En un proceso en dos etapas, a presión de CO2 mayor a 150 mm de Hg, la descomposición térmica procede como sigue (Ecuaciones 4 y 5) (Bogahawatta et al, 2004;Kristóf-Makó y Juhász, 1999;Santani et al, 2001):…”

Calcined Dolomite: Alternative to Lime for Minimizing Undesirable Element Leachability from Fly Ash

“…The relative amounts of these phases depend on the specific temperature, heating time, and the ambient CO 2 pressure . It has been found that the yield of MgO can be maximized and that of CaO minimized by heating dolomite at 740 °C in a pure CO 2 atmosphere. , The smaller size of Mg 2+ compared to Ca 2+ results in a greater mobility of magnesium in the dolomite structure, and thus, the easier detachment and escape of carbon dioxide associated to magnesium oxide during calcination. So the formation of MgO is kinetically favored over that of CaO .…”

An analysis of the chemistry, mineralogy and texture of waste dolomite powder used to identify its potential application in industry

“…Due to the chemical composition of the dolomite powder, consisting of more than 5% wt., CaO and MgO (Małolepszy et al 1994, Konik et al 2007, Kurdowski 2010, the material cannot be considered as potential replacement for clinker in cement production, even though the studies on calcination were promising because of the mineral phases formed. On the other hand, while the procedure of MgO extraction from dolomite is normally used (Beruto et al 2003, Bogahawatta et al 2004, the MgO extraction experiment from dolomite powder could be investigated. According to results obtained by Rashad and Baioumy (2005), MgO recovery was increased by decreasing the particle size.…”