Abstract
Generally light basic magnesium carbonate has the composition of “MgO: CO2: H20=(4:3:n) -(5:4:n)” mole-ratio. There is, however, another light basic carbonate of “2.0:1.2:2.1” mole-ratio, which was found by authors and made by passing CO2 gas into the aqueous suspension of Mg (OH) 2 at 90°C.
In this report, the relation between the bulkiness and crystal property of the above carbonate was studied by means of the X-ray analysis and the electron nticroscopy. The result is as follows:
1. The bulkiness of basic magnesium carbonate depends on the factors, such as the size and the lyophility of particles.
2. The single particle of “2.0:1.2:2.1” mole-ratio is composed of the flaky crystals of “5:4:5” moleratio, and each of these crystals are covered and sandwiched by the film of amorphous basic carbonate. Furthermore, the surface layers of these particles are more carbonated than the inner part, having the less hydrophilic property.
3. In order to be in the highly bulky state, therefore, the aggregates of fine flaky crystals must be dispersed, and also their surfaces must be less hydrophilic. Such conditionings are possible not only by the mechanical stirring, but also by the controlling of the CO2-adsorption in the process above mentioned.
