Abstract: The method permits recovery of spent foundry sand for reuse by eliminating, by combustion, the organic and carbon substances with which the spent sand is impregnated; spent sand, after grinding to a uniform grain size, is placed into a cylindrical container (2) inclined with respect to the vertical and rotated slowly (4-6 revolutions per minute); then, a stream of oxygen is blown into the base of the container through a distributor (5) which uniformly distributes it into the spent sand mass (20), and local combustion is initiated on the surface of the sand mass, at the top of container, by a burner (31); finally the burner is extinguished whilst the delivery of the oxygen stream is maintained and the combustion proceeds and feeds itself by the effect of a progressive descent of the flame front (30) towards the base of the container until complete destruction of the organic and carbon substances contained in the sand has taken place.