Investigations into the thermal utilization of secondary fuels in lump form in the cement burning process - Part 2. Commissioning and operating results for the first industrial application

The replacement of fossil fuels by uncomminuted old tyres in precalcining p lants with separate tertiary air supply has so far been limited by process engineering constraints to approximately 10 to 15 % of the total heat consu mption. A new thermal process, the development of which was discussed in ZK C INTERNATIONAL 02/99, allows the specific fuel fraction provided by old ty res to be increased by a factor of 2 to 3. This article describes experienc e with the first industrial application in a Swiss cement works. Proof of t he guaranteed nominal throughput of the plant of 3 t/h of old tyres was est ablished in June 2000. The NOx emissions from the kiln line when operating the pre-combustion chamber lie significantly below those when using fossil fuels alone.