This study examined the surface properties, fluidity, flowability and floodability of untreated ground calcium carbonate (GCC) powder and treated GCC powder with stearic acid (SA) using a dry process coating system. The surface of GCC powder is generally hydrophilic, but was changed to a hydrophobic surface when coated with SA. The contact angle of water on the coated GCC powder surface increased with increasing concentration of SA. The contact angle and hydrophobicity on the GCC powder treated with 1.0 mass% SA was 105 and 100%, respectively. The dispersive component of the surface free energy, D S of the untreated GCC powder determined using inverse gas chromatography (IGC) was 103 mJÁm À2 at 100 C. However, that of the GCC powder treated with 1.0 mass% SA was 34.8 mJÁm À2 . Kawakita's equations were used to characterize the properties of the powder. The fluidity index was increased from 18.60 to 30.39 when the surface of GCC powder was modified with SA. On the other hand, the characterization based on the method suggested by Carr showed that the flowability and the floodability of the GCC powder treated with SA increased from 45 to 53 and from 30 to 69, respectively. Therefore, the flowability and floodability of the GCC powder treated with SA were superior to the untreated GCC powder.

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