Reduction of CO2 emission in the whiteware wall tiles industry
CAILLIET S. 1, AZAR M. , POILLY C. 2, SÁNCHEZ E. 3, SANZ V. 3, CASTELLANO J. 3
1 Imerys, Toulouse, France; 2 Imerys, Aixe-sur-Vienne, France; 3 Instituto de Tecnología Cerámica (ITC), Universitat Jaume I (UJI), Castellón, Spain
In the aim of the decarbonisation of the European economy by 2050, the ceramic industry has to work on the reduction of its emissions with a target of 34 - 40% by 2030 and 83 - 87% by 2050. In the ceramic sector, achieving almost 90% emissions reduction will require radical changes in product design and available energy sources, and modifications of processes and technologies. Regarding the whiteware wall tiles compositions, the elimination/substitution of calcium carbonate raw material is essential to reduce CO2 emissions. Its thermal decomposition is responsible for CO2 emissions for two reasons: the decomposition itself and the need for a significant contribution of thermal energy (combustion of natural gas) due to the strong endothermic reaction.
In order to assess this topic, it is necessary to work on the raw materials sources and find potential candidates to replace partially or totally the calcium carbonate. Multiple candidates have been tested such as talc, pyrophyllite, wollastonite, and waste of fibreglass. Their effect has been studied on the formulation from the slurry to the fired pieces and compared to the standard formulation using calcium carbonate. The substitution allows to play on the firing cycle (FC) and to reduce the time of firing while keeping the same maximum temperature. The engobe and the glaze have to be compliant with the change of FC, therefore it is important to keep the thermal expansion of the body in an acceptable range. The substitution of calcium carbonate leads to changes in the properties of the fired pieces and might require adaptation of the ratio of each mineral in the formulation.
Pieces obtained with talc and pyrophyllite substitution and fired properties will be presented as well as the energy saving achieved thanks to the substitution.