At the heart of The Trefoil Process is the highly efficient Trefoil Rotary Kiln incorporating high temperature resistant alloys.

The shape of the kiln chamber is not dictated by the lining structure allowing the triple-lobed (trefoil) internal profile to be used. This greatly aids mixing and heat transfer within the kiln. The aggregate produced has a glazed outer surface that greatly increases aggregate strength. 

The kiln is designed to operate at temperatures above the critical 1100°C which is necessary to lock the heavy metal contaminates in toxic materials (contaminated mud, PFA, sewage and water sludge) into an unleachable state in the vitreous matrix of the lightweight building aggregates and sands produced.