The Morphology Control Of Superfine Calcium Carbonate And Process Of Modification

There are many kinds of morphology in calcium carbonate which can be applied in different industry. It needs to be surface modification when calcium carbonate is applied in polymer system. The morphology control of calcium carbonate has attracted more and more researchers’ attention. In order to control the morphology of ultrafine calcium carbonate, as carbonation reaction is a exothermic reaction, temperature control system needs to be used in production. This means a waste of energy and make production cost increase. The sub-micron spindle-like calcium carbonate and cubic calcium carbonate are synthesized by gas-liquid carbonization method by adding (NaPO3)6and A. The main effects are initial carbonation temperature and morphology control additive amount. The shape control mechanism of (NaPO3)6and A are studied. At the same time, the formation process of cubic calcium carbonate is discussed.The results turn out sub-micron CaCO3can be prepared when the initial temperature is30～35℃,(NaPO3)6mass fraction is0.8-1.2%. Its radial length is200～600nm and the radio of radial length to axial length is4. Furthermore, the nucleation rate increased and the growth rate decreased when (NaPO3)6is added into Ca(OH)2slurry because the steric hinerance is increased.The cubic calcium carbonate can be synthesized when initial temperature is25～35℃and adding0.8～1.2%A as morphology control agent. The formation process of cubic calcium carbonate is discussed. The reaction temperature is important to the morphology of PCC. The cubic PCC can be prepared only when constant temperature is lower than30℃. The length of calcium carbonate is enlarged with the initial temperature.The surface organic modification of nano-CaCO3with sodium stearate was carried out. It focuses on the effect of modification process on modification effect and energy consumption. The results turns out that oil-absorbed value is99.8%when adding sodium stearate before carbonation starts and keeping the pH of suspension is about10for2h.