Specialized contact kneader/dryers are applied to dry materials that exhibit a multiple phase change while contained volatile components are evaporated. During drying, a multiple phase change is manifested by gradual but continuous change in rheological consistency of process material from liquid to highly viscous, pasty and eventually, but not necessarily to a free-flowing solid. Side effects such as foaming, stickiness or crust formation, difficult product flow, fluctuation of product temperature, and power uptake often occur. LIST USA INC. 1629 Cross Beam Drive Charlotte, NC, 28217