Papers by Author: Sang Hwan Cho

Abstract: Homogeneous precipitated calcium carbonate(PCC) was synthesized by calcinations, hydration and carbonation of limestone which has been deposited in Danyang, Korea. In the reaction process, shapes(scalenohedral and cubic) and sizes(0.2~0.3μm and 2.0μm) of the powder were controlled by reaction temperature. Synthesized PCC was applied to hand-made paper as filler and coated paper. For the prepared papers, physical/optical properties(brightness, whiteness, opacity, roughness, gloss, tensile strength, internal tearing strength, stiffness, bursting strength) and printability(ink gloss, ink set-off, dry pick, wet pick) were characterized

Abstract: The effect of the impurity ions Al3+, Fe3+ and Mg2+ on the formation yield and crystal properties of precipitated calcium carbonate(PCC) produced by the carbonation process was investigated in Ca(OH)2-H2O-CO2 system. The effect of the impurity ions Al3+, Fe3+ and Mg2+ on the formation yield using particle size distribution and morphology of PCC were discussed. The particle size distribution of PCC was increased with increase of impurity ions. The morphology was transformed in order of spheroidal, scalenohedral, rhombohedral calcite for Al3+, Fe3+ and rhombospheroidal, spherical, scalenohedral for Mg2+ with increase of impurity ions.

Abstract: Non-isothermal behaviors of calcium carbonate using Danyang limestone were investigated. It was attempted to provide non-isothermal data with a precision sufficient for the determination of reliable decomposition behaviors and for the estimation of accurate kinetic parameter. The decomposition temperature of calcium carbonate on the onset, peak and final point were measured. Reaction rate was decreased and maximum reaction temperature was increased with increasing heating rate. Activation energy of Danyang limestone was 45.14㎉/㏖ and 50.80㎉/ ㏖ by Kissinger method and Freeman method, respectively.