At the Saint-Pierre-la-Cour cement plant in France, Holcim has developed and commissioned its own patented technology to produce calcined clay with the lowest-possible CO2 footprint, 100 per cent alternative fuel use, low thermal energy requirement, and innovative colour control. The successful project start-up marks the first calcined clay, low-carbon cement operation in Europe, with scope for further potential. By Rudy Blum, Ernst Bucher and Michael Weihrauch, Holcim Technology Ltd, Switzerland.
Calcined clay cements will play an important role in further reducing the carbon footprint of cement. Numerous projects and new technologies are under development. However, calcined clay projects are often hampered by a few challenges such as:
• insufficient deposits with large enough quantities of suitable kaolinitic clays
• insufficient payback due to high investment and operating costs
• technological restrictions in the use of alternative fuels
• elevated emission coming from clay and fuel that require capex intense secondary abatement measures
• difficult clay colour control
• difficult material handling properties of raw and calcined clay outside of the classical experiences
• required adaptation of downstream cement production process including for example separate grinding
• change in market acceptance due to the altered cement quality parameters such as colour, early strength, and water demand of the concrete.
