Estimation of fluorine and chlorine emissions from Spanish structural ceramic industries. The case study of the Bailén area, Southern Spain

This paper assesses F and Cl emissions as atmospheric pollutants in the Bailén area (southern Spain), originated from the raw material used in structural ceramic industries. The area is one of the most important in Spain, with a daily output over three million pieces. The Bailén area features three categories of industries taking into account F emissions (the most important pollutant from ceramic clays): Group I: Those releasing less than 150 ppm F, which use raw materials with low F contents and/or high proportion of calcite, and fire at about 850°C. Group II: Those releasing 150–300 ppm F, whose raw materials show low calcite percentages and bricks are fired between 850–1050°C. Group III: Those releasing more than 300 ppm F, which use clays containing over 1000 ppm F and firing temperatures around 900°C. The emission rate of F increases with increasing F content in the raw material and firing temperature (particularly when exceeding 1000°C). The calcite and clay mineral contents control the F emissions up to 950°C; on the other hand, a high heating rate hinders fluorine emission to some extent. The emission rate of Cl increases with increasing temperature, but in the most cases chlorine is released at concentrations below 30 ppm. Atmospheric contamination in the Bailén area can reach 3 kg/h of fluorine and up to twice of chlorine emission levels permitted, owing to the massive production of structural clay products.