Characterization of clay deposit in the central region of Piauí for use in the ceramic industry

ABSTRACT The clay ceramics industry comprises materials used in construction (bricks, tiles, and expanded clay, among others), is of great importance for Brazilian economic development, and the industry is seeking new sources of raw material, mainly clay. The present work aims to characterize a clay deposit located in the central region of the state of Piauí, to make feasible its use as ceramic raw material, seeking to boost the clay ceramics industry. The chemical composition, the crystalline phases, and the plasticity of the clay were analyzed. Specimens were prepared by uniaxial pressing, dried in an oven at 110 °C, and then heated to 900 °C, 1000 °C, and 1100 °C. Bending strength, apparent porosity, linear shrinkage, water absorption, and mineralogical, macrostructural, and microstructural analyses were determined. The results showed an improvement in the indices with the increase in the firing temperature and that the samples showed a reddish coloration due to the presence of iron, as well as quartz and kaolinite. Thus, the clay deposit has the potential to become raw material for the clay ceramics industry in the state of Piauí.

摘要 黏土陶瓷工业涵盖建筑领域所用各类材料（砖、瓦、陶粒（expanded clay）等），对巴西经济发展至关重要，当前该行业正积极探寻新型黏土类原材料来源。本研究旨在对位于皮奥伊州（Piauí）中部地区的一处黏土矿床开展性能表征，以验证其作为陶瓷原材料的可行性，助力皮奥伊州黏土陶瓷工业的发展。本研究对该黏土的化学成分、晶相组成（crystalline phases）及可塑性（plasticity）进行了分析。实验采用单向加压成型（uniaxial pressing）法制备试样，将试样置于110℃烘箱中烘干，随后分别升温至900℃、1000℃及1100℃进行煅烧。本研究完成了试样抗弯强度（bending strength）、显气孔率（apparent porosity）、线收缩率（linear shrinkage）、吸水率（water absorption）的测试，以及矿物学分析、宏观结构与微观结构的表征。结果表明，各项性能指标随煅烧温度升高而显著优化；试样因含铁质、石英（quartz）及高岭石（kaolinite）而呈现红褐色泽。综上，该黏土矿床具备成为皮奥伊州黏土陶瓷工业原材料的潜力。