The Queen Domination Problem

An improved seal is provided at the entrance of a de-airing chamber, which removes air from abrasive particulate matter as it is fed to an auger that forces the same though an extruder die to form an extrusion. The seal includes a sealing die whose wall is coaxial to the travel direction of the particulate matter entering the chamber and a sealing core that has flights for directly forcing the particulate matter through the die into the chamber while the particulate matter cooperates with the sealing die and sealing core to block the escape of vacuum from such chamber. Steam or other lubricant may be injected into the particulate matter at or upstream of the seal to facilitate the flow of particulate matter through the seal. Fluid, such as steam, also may be injected directly into the particulate matter at the pug mill as an additional lubricant and/or as an activator to enhance the binding characteristics of a binder material combined with the particulate matter.