Mineralogical and Thermal Characterization of Kaolinitic Clays from Terra Alta (Catalonia, Spain)

Maite Garcia-Valles,Salvador Martínez,Núria Roca,Pura Alfonso

doi:10.3390/min10020142

Maite Garcia-Valles, Salvador Martínez + Show 2 more

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https://doi.org/10.3390/min10020142

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Abstract

This research characterizes the kaolinitic clays from Cretaceous–Paleocene lateritic deposits of Terra Alta (south Catalonia) to evaluate their possible applications. The outcrops and quarries belong to the Horta de Sant Joan and Pinell de Brai areas. The chemical composition, mineralogy, rheological behavior, particle size distribution and plasticity are determined. The Fe and Ti4+ contents prevent them from being directly used as raw material for white ceramics. The mineralogy consists of kaolinite with quartz, illite, hematite, and minor K-feldspar and calcite. Most of the area comprises medium plastic clays that are classified as fired clays and can be used as ceramic and construction materials. In Horta de Sant Joan, a kaolinitic-rich level, up to 75 wt % of kaolinite, is highly crystalline with low plasticity and can be classified as flint clay, useful as a refractory clay. The evaluated kaolinitic clays can also be used to obtain a triaxial ceramic when they are mixed with feldspar to act as a fluxing agent and chamotte.

Highlights

Kaolin is highly important for industry, especially due to its specific properties that benefit a large number of applications [1,2,3]
Kaolin mining started in the Neolithic, when people discovered its suitability for painting; previously, the miners had transformed this raw material into a form that could be more readily applied to surfaces [4]
Most of this raw material is employed for papermaking [5], and another common application is in the manufacture of whiteware ceramics, because of its excellent firing properties and relatively high melting point

Summary

Introduction

Kaolin is highly important for industry, especially due to its specific properties that benefit a large number of applications [1,2,3]. Kaolin mining started in the Neolithic, when people discovered its suitability for painting; previously, the miners had transformed this raw material into a form that could be more readily applied to surfaces [4]. Nowadays, most of this raw material is employed for papermaking [5], and another common application is in the manufacture of whiteware ceramics, because of its excellent firing properties and relatively high melting point. A technological classification of kaolinitic clays according to their possible applications distinguishes between ball clays, brick clays, fire or refractory clays, flint clays, bloating clays and underclays [7]

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