Ozonation of ceramic raw materials to optimize fuel consumption and greenhouse gas emissions in ceramic tile processes

Abstract The concern with greenhouse gas emissions has justified efforts to increase energy efficiency in industrial processes. In the ceramics sector, the firing stage accounts for the highest fuel consumption. Excess oxygen in firing gases is one factor that increases fuel consumption. Oxygen fractions above 8% are usually applied to oxidize organic carbon from humic acids in plastic clays. Low oxygen levels combined with high humic acid content promote the occurrence of the defect known as black core. This study aimed to apply ozonation to reduce humic acid levels, thus minimizing the formation of black core in atmospheres with low oxygen content. An industrial powder composition was exposed to four ozone concentrations, ranging from 12 to 64 g O 3 /Nm 3 , for up to 6 h. Test specimens were produced to evaluate effects under firing in an atmosphere with 1% O 2 . Additional technological characterizations were performed to assess any changes in relevant properties during the manufacturing stage. Ozonation under the applied conditions led to a 25% reduction in the incidence of black core, without affecting other product characteristics. The proposed method allows for a reduction in the oxygen content during firing, potentially reducing fuel consumption by approximately 3%.