Process for extraction of sulphur and metals, in oxide form, usable in the Waeltz process, from sulphur and said metal compound containing muds, for example from jarosite and goethite chemically similar substance containing muds, said method comprising the following operations: - optional mud drying; - introduction into closed main reactor; - heating under oxidizing atmosphere until melting; - transformation of metal containing compounds in oxides that remain in melt bath and of sulphur containing compounds in SOx gas, that is extracted with gaseous flow exiting from said melt bath through off-gas line; - discharge of resulting metal oxides and fast cooling thereof; - addition to discharged oxides of possible powdered metal oxides recovered by filters placed in off-gas line; - grinding of recovered metallic oxides and use thereof as feed product for Waeltz process; - reduction, by reducing gas, of melt bath exited SOx in a plasma generated inside a first arc-plasma reactor thus resulting in formation of elemental S that successively is condensed and recovered; - at least once optional repetition, in a subsequent plasma reactor, of reduction for not yet reduced SOx fraction exiting from preceding plasma reactor, along with CO, H 2, H 2 S and COS, with successive condensation of obtained sulphur added to that recovered after the first reduction; - cooling of residual gas, mainly containing CO, H 2, H 2 S and COS with a very small fraction of SO x, at a temperature < 50°C, thus recovering, in condensed form, SO 3 residual fraction that is returned to first plasma reactor; - arc-plasma reducing treatment of residual fraction, without exogenous reducing agent addition, resulting in formation of CO, H 2, H 2 O, CO 2 and SO 2 containing syngas. - optional mud drying; - introduction into closed main reactor; - heating under oxidizing atmosphere until melting; - heating under oxidizing atmosphere until melting; - transformation of metal containing compounds in oxides that remain in melt bath and of sulphur containing compounds in SOx gas, that is extracted with gaseous flow exiting from said melt bath through off-gas line; - discharge of resulting metal oxides and fast cooling thereof; - discharge of resulting metal oxides and fast cooling thereof; - addition to discharged oxides of possible powdered metal oxides recovered by filters placed in off-gas line; - grinding of recovered metallic oxides and use thereof as feed product for Waeltz process; - reduction, by reducing gas, of melt bath exited SOx in a plasma generated inside a first arc-plasma reactor thus resulting in formation of elemental S that successively is condensed and recovered; - at least once optional repetition, in a subsequent plasma reactor, of reduction for not yet reduced SOx fraction exiting from preceding plasma reactor, along with CO, H 2, H 2 S and COS, with successive condensation of obtained sulphur added to that recovered after the first reduction; - grinding of recovered metallic oxides and use thereof as feed product for Waeltz process; - reduction, by reducing gas, of melt bath exited SOx in a plasma generated inside a first arc-plasma reactor thus resulting in formation of elemental S that successively is condensed and recovered; - at least once optional repetition, in a subsequent plasma reactor, of reduction for not yet reduced SOx fraction exiting from preceding plasma reactor, along with CO, H 2, H 2 S and COS, with successive condensation of obtained sulphur added to that recovered after the first reduction; - cooling of residual gas, mainly containing CO, H 2, H 2 S and COS with a very small fraction of SO x, at a temperature < 50°C, thus recovering, in condensed form, SO 3 residual fraction that is returned to first plasma reactor; - arc-plasma reducing treatment of residual fraction, without exogenous reducing agent addition, resulting in formation of CO, H 2, H 2 O, CO 2 and SO 2 containing syngas.