Effects of organic matter, soluble salts and characteristics of ball clays on their rheological and casting properties

Abstract

Characteristic features of ball clay that have influence on slip rheology and casting properties were studied. The ball clay samples were classified into 3 groups; 11 samples: the first group is local ball clays having good rheological and casting properties, the second group is imported ball clays having superior rheological and casting properties and the last group is ball clays that have inferior rheological and casting properties. For comparative study, the samples were investigated with 4 groups of characterizing techniques, the first is general characterization which consist of chemical, mineralogical and microstructural together with partical size distribution analysis. The second is organic matter characterization such as total carbon, inorganic carbon and organic carbon. Extractable humic substance were quantitative analyzed and classified into humic acid and beta-humus then identified by Nuclear Magnetic Resonance Spectroscopy (NMR). The third group is soluble salts analysis of 6 cations and 6 anions including total dissolved solid, carbonate hardness and non-carbonate hardness. The last feature is rheology and casting properties by studying about defloccolation response, gelation, relative gel-strength, shear response, viscosity and thixotropy. For casting rate test were made with Baroid Filter Press and plaster mold. The results confirm that organic matter and soluble salts in each group of ball clays have influence on rheological and casting properties. Finally, efforts had been made by adding extractable humic acid from some ball clay samples and commercial humic acid to low organic ball clay to study their rheological and casting properties. The results of this intensive sanitaryware ball clay characterization will benefit ball clay manufacturers and sanitaryware industry. They can use this information to improve in quality control of Thai ball clays. The ultimate advantage was to establish the new concepts of organic matter selection and production and finally towards the production of high quality ball clays for the sanitaryware industries. This research consists of 90 figures, 8 tables and 38 references.