Flash calcination of magnesite in a one-throughput transport bed: reaction characterization and industrial justification

Abstract

This study investigated flash calcination of magnesite powder in a one-throughput transport bed to clarify how the conversion and product activity as well as microstructure vary with reaction conditions including temperature, particle size, and numbers of re-calcination. Results showed that calcination of magnesite powder at 850–1000 °C is a quick reaction, allowing 99% of its containing MgCO to be decomposed in 1–2 s. Activity of product from the transport bed flash calcination (TBFC) is obviously higher than that from fixed bed calcination. Product activity depends on both decomposition rate and microstructure. During calcination, the surface structure of product changes from loose and porous to dense and smooth, even in a few seconds. A recently commissioned commercial TBFC plant indeed produced the light-burned magnesia according to the anticipation of this study, and it only requires a fuel consumption about 40 % lower than that of conventional reverberatory furnace.