There is provided a continuous combustion system for iron particles. The system comprising a multi-annular combustion tube defining in cross-section at least three distinct passages from its inlet to its outlet. A first tube that is innermost, defines a first passage providing a primary air flow with suspended iron particles. A second tube, defines an inner annular space providing a secondary air flow, a pilot combustible flow, and an ignition point of a spark generator. A third tube defines a third passage comprises a swirl generator and provides a tertiary air flow. The tubes are nested in position within the multi-annular combustion tube. The system comprises a divergent nozzle at the outlet of the multi-annular combustion tube: a combustion reactor in fluid communication with the divergent nozzle, for the generation and stabilization of a turbulent iron flame that burns the iron particles and produces oxidized iron particles; and a cyclone.