Abstract: The invention relates to a system for recovering thermal energy produced in pyrometallurgical process plants and converting said thermal energy into electrical energy. The system is characterised in that it comprises at least one heat transfer chamber (1) comprising a gas interface section (1A), for separating the subsystem from the corrosive power of, and incrustation generated by, the gases from the heat source or duct (5). The system also comprises a section (1B) for connecting to a Stirling engine (2), which is a thermal engine and which, by means of the cyclical compression and expansion of a gaseous working fluid, at different temperature levels, produces a net conversion of thermal energy into mechanical energy.