A proposal for reducing F and Cl emission in the brick industry using new formulations

Emissions of F and Cl by the brick and tile industry of Bailén (Jaén, Spain) can be reduced by preparing mixtures of the three clays traditionally used in that area (white, and blonde Tertiary loams and Triassic red loam), which F content ranges between 850 and 1200 ppm, with an Al-rich clay of low F content (<350 ppm). In the proposed formulations, ceramic properties were improved, F is lowered to 570–950 ppm, and during the heating process, F emission was in most cases lower than 100 ppm at 850 °C. At 1000 °C, the emission was higher, mainly when red Triassic clay was included in the mixture. This loam should be avoided in percentage >30% because its higher F initial content and its lower proportion of carbonate produce higher emissions. For Cl, the initial content is very low (<70 ppm) and does not represent a source of contamination although the emission at 1000 °C can reach up to 80% of the initial content. The new formulations lead to produce paving bricks and, in some cases, porous wall tiles.