Emissions

Abstract

Of the pollutants emitted with exhaust gases from kilns in the brick and tile industry fluorine is of special importance. Fluorine is present in very low quantities of 0.01 to 0.1% in the raw materials used by the brickmaking industry. During the combustion process some of the fluorine is released in gaseous form as hydrogen fluoride (HF) and emitted with the exhaust gases. The absolute quantities emitted in a tunnel kiln are only of the order of 0.1 to 0.8 kg F per hour, depending on kiln efficiency. This means that the brickmaking industry is certainly a very small emitter of fluorine in comparison with other industries. Among the methods for reducing emissions of gaseous fluorine, the first to be mentioned must be combustion engineering measures. During the firing process a so-called fluorine cycle is produced, in which the fluorine contained in the clay is released in the form of hydrogen fluoride gas.