A pallet car for conveying material to be processed is disclosed. The pallet car includes first and second sidewalls formed from sidewall members that each include a metal frame and a heat-resistant liner, such as formed from refractory. The refractory formed on the metal frame of the sidewall members provides insulation for the metal frame without the need for a hearth layer of pre-processed material in the material bed of the pallet car. The sidewall member including the refractory layer increases the effective volume of the pallet car, which increases the overall efficiency of the furnace and material processing procedure.