In the "Dry-Control" project, a resource-efficient drying technology was developed for ceramic products with process-integrated testing. The quality of products in the minerals industry can be significantly improved by optimizing the drying process. This lowers the rate of rejects and conserves resources.
In the ceramic industry, about five to ten percent of the green bodies still have localized humid patches even after drying. Conventional secondary drying of these patches is very energy-intensive and uneconomical. About three to five percent of total production is destroyed during firing because cracks appear due to these humid patches.
In order to avoid these cracks, the project partners developed a new method using microwave application: The conventional drying of green bodies sanitary wares is supplemented and improved with microwave drying. Remaining humid patches are located using microwaves and quickly dried using localized microwave radiation. After drying, the green body is tested for hidden cracks using infrared thermography. RFID technology that is integrated in the production process makes it possible to seamlessly track the parts.
These new developments help to significantly lower the reject rates in the ceramics industry which improves sustainable management: For one million produced parts, there is a saving potential of 1,550 tonnes of raw materials (clay, kaoline, feldspars, nepheline, quartz flour, glass and grog), 10,000 to 15,000 megawatt hours of energy, 1,500 to 2,200 tonnes CO2 emissions and 16,000 to 29,000 m³ of water and wastewater. On top of this, the landfill space required can be reduced by at least 3,000 m³.
The thermographic techniques used during process control can also be used for other applications, for example, to manufacture products based on sintered metal, in the food or packaging industries. The results from the microwave drying can be applied to the entire thermal process technology.