An automatic dross processing system has a pivotably-mounted reaction vessel and a vertically movable motor and impeller. A microprocessor controls the operation of the motor and a series of actuators that move the motor vertically, move a probe that removes a plug to drain collected metal from the reaction vessel, and move the reaction vessel between a loading-and-processing position and a dumping position. The microprocessor coordinates the actions of these elements to complete a dross processing cycle to recover metal from a dross without requiring the attention of an operator throughout the process. The reaction vessel can have an inner shell and an outer shell that are bolted together with a gap therebetween to accommodate insulation, which can include a felt overlying one or more pieces of rigid material. A drain tube can be attached to the inner shell by an accordion-like structure to reduce thermal stresses in service.