(Assessment of new clay deposits of Paraíba State for application as ceramic raw materials)

Abstract

In recent years, new clay deposits have been discovered in the state of Paraíba, Brazil, the characterization of these deposits having fundamental importance to establish the best industrial application. The aim of this study was to characterize clays from Cubati, PB, Brazil, to establish their appropriate uses as ceramic raw materials. Therefore, the raw materials were subjected to physical, chemical, mineralogical and thermal characterizations. The specimens were prepared by uniaxial pressing at 19 MPa, dryng at 110 ºC, and fired at 750, 850, 950 and 1150 ºC. The following physical and mechanical properties were studied: firing linear shrinkage, water absorption, apparent density and flexural modulus of rupture. The results showed that SiO₂, Al₂O₃ and Fe₂O₃ were the main oxides present in the clays, whicht are constituted by smectite, kaolinite and quartz. The clay containing higher Al₂O₃/SiO₂ratio, wider size distribution and the lower average particle diameter was the one that presented best mechanical performance. Three clays are suitable for use in white ceramic and one to red ceramic.

Keywords:
clays; characterization; properties