Ash from sunflower husk as raw material for ceramic products

The objective of the present work was to characterize a residual material (ash) from edible oil industrial production and to study its feasibility as a starting material for fabrication of ceramics for the construction industry. The characterization of the ash was carried out by a range of techniques, such as humidity content measurement, particle size distribution analysis, weight loss on calcination, scanning electron microscopy and chemical composition analysis by X-ray dispersion energy and X-ray diffraction. The ash was compacted without other additions into “green bodies”, which were treated at different temperatures in order to determine the sintering behaviour, and the occurrence of possible chemical reactions at the processing temperatures. From the experimental results and the analysis of the equilibrium diagrams of the major oxides present, the theoretical sintering temperatures were determined to be too high for an attractive cost-effective industrial scale process. Therefore new mixtures were designed adding different contents of milled discarded (cullet) glass to the ash in order to lower the working temperature. Final sintered products containing 30%, 40% and 50% of ash were produced which exhibit adequate properties for their use as ceramic products with a typology of lightening bricks.