Abstract
The change in mechanochemical behavior of basic magnesium carbonate (4MgCO3·Mg(OH)2·4H2O) caused by vibrational grinding was investigated by means of the scanning electron microscopy (SEM), specific surface area measurement, X-ray diffractometry, infrared absorption spectroscopy, and thermoanalysis.
It was found that the generation of fine particles and their granulation occurred in grinding from the observation in SEM. The specific surface area showed the maximum value at 20min, and decreased to a constant value after prolonged grinding.
It was found from the powder X-ray diffraction patterns of the ground basic magnesium carbonate that the structural lattice irregularity and an amorphous phase were formed by grinding, and their amounts increased gradually with increasing grinding time.
The effect of grinding on the pyrolysis of basic magnesium carbonate was also studied. From the X-ray diffraction patterns of the products made by pyrolyzing the original basic magnesium carbonate and the ground one at the heating rate of 2°C/min, it was found that the crystallized MgCO3 was produced in the dehydration reaction of the ground basic magnesium carbonate, while MgCO3 produced by the dehydration of the original basic magnesium carbonate was only the amorphous phase. It was also found from the result of thermoanalysis that the reaction rate of dehydration of the ground basic magnesium carbonate was higher than that of the original basic magnesium carbonate, whereas the reaction rate of decarbonation of the ground basic magnesium carbonate was lower than that of the original basic magnesium carbonate.
