Evaluation of Linamon Red Clay, Salvador Black Cinder and Kapatagan Diatomaceous Earth of the Southern Philippines

Abstract

The southern island of the Philippines is abundant in silicate minerals, including the province of Lanao del Norte. However, some of these resources in the region are untapped for use as raw materials in the production of various ceramic products for industrial, pharmaceutical, and nanotechnology applications. These could include tiles, sanitary ware, dinnerware, insulating bricks, porcelain, membranes and coatings. Some of the explored minerals are the red clay in the municipality of Linamon, diatomaceous earth in Kapatagan and black cinder in Salvador. It is the aim of this study that these minerals are evaluated in terms of their physical and chemical properties so that these will be used for optimum application. The properties that were determined were their specific gravities, raw and fired surface colors, Atterberg limits, particle size distribution, thermal properties, morphologies and mineralogical compositions. Pellets were formed for each raw material and fired at two temperature levels 1000 °C and 1200 °C to evaluate their physical properties. Linamon red clay has a 38.88% cumulative passing size of 150 µm, and the black cinder of Salvador and diatomaceous earth of Kapatagan have cumulative passing sizes of 96.53% and 60.12% at 150-micron sieve, respectively. The common mineral contents of the three samples are montmorillonite, quartz and andesine. Black cinder fired at 1200 °C has the darkest shade of red with a greasy quasi-submetallic luster. It attained the highest fusion coverage on the platform among the three materials, which makes it a potential supplement or replacement for feldspar in clay-based triaxial materials for ceramic production. The diatomaceous earth has the potential to be a secondary clay content source and a good source of flux for a certain temperature range. Both the red clay and diatomaceous earth were classified as plastic materials that are suitable for brick production, and the red clay is also feasible for pottery production. These are a few of the features of the clay minerals in the region that present suitable properties for application as raw materials in the production of ceramic tiles and hollow ceramic products.