Plastic conversion vessels such as pyrolytic reactors convert plastic waste materials such as polymers, or hydrocarboneous material, or both, via in situ chemical reactions comprising cracking, recombination, reforming, recracking, and the like, to usable chemical compounds such as naphtha, diesel fuel, heavy oil, wax, and the like. Inherent within the polymers and/or carbonaceous material are generally solid, inert residues such as various fillers, pigments, flame retardants, silica, aluminum, talc, glass, clay, and so forth. Such solid inert residues (SIR) must be treated to remove residual volatile organic material therefrom in order to meet acceptable environmental standards and/or limits. A heated dryer for treating the SIR comprises heating units to remove excessive volatile organic material therefrom as when moved along a conveyor that transfers said material to a collection area. The collection area comprises one or more pistons that are capable of compacting and discharging said SIR material. Another collection area embodiment comprises a plurality of plungers that transfer the SIR material from said collection area to a plunger collection area, and subsequently to a collection container.