Effect of trisodium phosphate on the decomposition of dolomite

Abstract

Dolomite calcination is of important industrial significance in versatile scenarios. This paper reports the effect of trisodium phosphate on dolomite decomposition. The thermogravimetric tests showed that the dolomite with 1.0 wt. % Na3PO4 (Na3PO4-dolomite) partially decomposed into MgO and magnesian calcite (Mg-CaCO3) and the formed Mg-CaCO3 then decomposed subsequently. The Na3PO4 lowered the temperature and significantly enhanced the rate of partial decomposition of dolomite. The change in the apparent activation energy (178.5-104.0 kJ/mol) versus the conversion indicated that multiple steps were involved in the partial decomposition of Na3PO4-dolomite. In the partial decomposition, Mg-CaCO3 with different Mg contents and MgO formed as final products. The Mg content of the Mg-CaCO3 was dependent on the calcination conditions. High-magnesian calcite (>10 mol% Mg) was obtained by calcining Na3PO4-dolomite at 873 K within 60 min.