President of the ICG International Commission on Glass
Retired Professor from RWTH Aachen University, DE



Reinhard Conradt is a retired professor from RWTH Aachen University, Germany. He has been performing glass research at Fraunhofer Institute of Silicate Science, ISC Würzburg, Germany, for six years, then served for ten years as university lecturer and industry consultant at Chulalongkorn University, Thailand. From 1997-2016, he was full professor and Chair of Glass & Ceramic Composites at RWTH Aachen University, Germany Since 2022, he is President of the International Commission on Glass ICG.

His work has been committed to building bridges between science, especially chemistry, thermodynamics and kinetics, and industrial engineering.

  • International Otto Schott Research Award 2001,
  • Fellow of The Society of Glass Technology (SGT, U.K.) 2017,
  • L. David Pye Lifetime Achievement Award (GOMD-ACerS) 2020,
  • Otto Schott Memorial Coin of DGG 2021.

​Presentation ​

Enhancing Furnace Performance by the Choice of Raw Materials

The technological goal of the glass melting process is the production of a glass with a specific composition, at a desired quality level, at high production efficiency, at low specific energy consumption, and at low environmental impact. All of these issues have a direct influence on the production costs. During the past decades, the above goal was predominantly pursued by improving the design of glass furnaces. This development has, by and large, reached as level of saturation. By their basic function, all glass furnaces are high-T chemical reactors. So, beside the features of furnace design, their performance depends on the material passing through the reactor volume. Thus, the set of raw materials used to melt a specific glass is a powerful lever to optimize furnace performance. The present talk draws the attention to this approach, pointing out its chances and limits.


The choice of raw materials influences furnace performance is several ways. This is, first of all, the energy demand of the batch-to-melt conversion, which is a 1st law property. Second, this is the batch gas inventory contributing to the overall flue gas volume. Together with the redox potential of the raw materials, it also governs foam formation. Third, this is the reaction rate of the batch-to-melt conversion, a kinetic property depending on the mineralogi-cal nature and the grain size distribution of the raw materials. In this context, the option of batch conditioning will be addressed, too. Industrial case studies are presented clearly showing that the furnace performance can be enhanced by optimizing the above influences. The limits of such optimization measures are, however, set by raw material availability and costs.