Chloride salt effects on the decomposition of dolomite

A great deal of variability in decomposition temperature(s), activation energy and rate of decomposition exists in the literature on the decomposition of dolomite. Although differences may be due to experimental factors such as sample size, grain size, heating rate and atmospheric conditions, it has been found that the presence of small concentrations of alkali or alkaline earth salts in the naturally occurring minerals has a strong effect on their decomposition. From DTA and isothermal studies, it is illustrated that the temperature of decomposition of dolomite is reduced and that the rate of decomposition is enhanced relative to pure dolomite when small amounts of chloride salts such as LiCl, NaCl, MgCl₂ and CaCl₂ are added. From X-ray analysis, pure dolomite is seen to decompose directly into CaO and MgO, but when chlorides are present it initially decomposes into MgO and CaCO₃. The decomposition reaction for both pure dolomite and dolomite containing chlorides follows the contracting-area model 1 - (l - α) ^{1 2}= kt Activation energies for pure and doped dolomites have been evaluated and are similar to those reported in literature.