Fluorine control in ceramic gaseous emissions

Abstract

One of the major environmental issues within the ceramic industry is the fluorine emission in the flue gases exhausted during the firing process. European and National regulations limit these emissions, and there is a trend towards the harmonization and restrictions of these limits among the EU countries.The present study reports the investigation of the fluorine emissions process, from the raw materials (chemical composition and fluorine content, crystal nature, effect of selected body additives) to the thermal process control (heating rate, peak temperature, oxygen and water vapour pressure and overall flow of gases in kiln atmosphere).A laboratory scale apparatus was developed to study the effect of several parameters on the emissions during firing.The experiments results show that some primary measures can be adopted in industrial operation to reduce fluorine emissions of clay based ceramic materials by means of adjustments in body composition and the control of the atmosphere and firing cycle.