A plant for recycling of white slag which is generated during a steel production step, comprising: - a rotating cylinder internally of which the white slag is housed in a controlled atmosphere; the rotating cylinder comprising a first portion in which a controlled cooling is carried out so as to lead to a withering process of the white slag, with a consequent detachment of fragments and powders, and a second portion, located in cascade from the first portion, in which the selection and the separation takes place of the fragments and powders of the white slag having a smaller grain size than a predetermined grain size; - first means (90, 19, 19a) associated to the second portion of the rotating cylinder, for extraction of the fragments and powders of the white slag having a grain size that is on average smaller than a predetermined size; - second means, located in cascade to the second portion of the rotating cylinder, for extraction of the fragments and powders of the white slag having a grain size that is on average higher than a predetermined size, - a space afforded in the mantle of the first portion of the rotating cylinder; - a cooling fluid contained internally of the space for enabling an indirect cooling of the white slag contained internally of the first portion of the rotating cylinder; - means for feeding the cooling fluid into the space in a closed circuit; the plant being characterized in that it comprises: storage means of the white slag; feeding means of the white slag from the storage means to the first portion of the rotating cylinder; wherein the first means (90, 19, 19a) and the second means enable extraction of the fragments and powders of the white slag in a continuous cycle with the rotation of the rotating cylinder, and in that the storage means of the white slag comprise: - a hopper peripherally provided with a space containing a cooling fluid, so as to enable a first cooling of the white slag prior to inlet thereof into the first portion of the rotating cylinder; - an overflow, positioned superiorly of the hopper, frontally of the feeding zone of the white slag, provided for separating the white slag from any liquid metal still possibly present; the overflow having, on a side thereof facing the hopper, a containing head which enables retaining the liquid metal in the overflow, and facilitating passage of the white slag, which floats on the liquid metal due to the specific weight difference there-between, towards the underlying hopper. - a rotating cylinder internally of which the white slag is housed in a controlled atmosphere; the rotating cylinder comprising a first portion in which a controlled cooling is carried out so as to lead to a withering process of the white slag, with a consequent detachment of fragments and powders, and a second portion, located in cascade from the first portion, in which the selection and the separation takes place of the fragments and powders of the white slag having a smaller grain size than a predetermined grain size; - first means (90, 19, 19a) associated to the second portion of the rotating cylinder, for extraction of the fragments and powders of the white slag having a grain size that is on average smaller than a predetermined size; - second means, located in cascade to the second portion of the rotating cylinder, for extraction of the fragments and powders of the white slag having a grain size that is on average higher than a predetermined size, - a space afforded in the mantle of the first portion of the rotating cylinder; - a cooling fluid contained internally of the space for enabling an indirect cooling of the white slag contained internally of the first portion of the rotating cylinder; - means for feeding the cooling fluid into the space in a closed circuit; storage means of the white slag; feeding means of the white slag from the storage means to the first portion of the rotating cylinder; wherein the first means (90, 19, 19a) and the second means enable extraction of the fragments and powders of the white slag in a continuous cycle with the rotation of the rotating cylinder, - a hopper peripherally provided with a space containing a cooling fluid, so as to enable a first cooling of the white slag prior to inlet thereof into the first portion of the rotating cylinder; - an overflow, positioned superiorly of the hopper, frontally of the feeding zone of the white slag, provided for separating the white slag from any liquid metal still possibly present;