Plant for the production and distribution of bituminous conglomerates comprising: - at least one dryer for drying materials to be treated wherein the at least one dryer is provided with a burner generating drying heat for the materials to be treated by means of at least one flame of the burner, obtaining treated materials; - a mixer for mixing at least the treated materials; - a control unit; wherein the plant is adapted and intended for the treatment of the materials to be treated including inert lithic materials and materials containing bitumen, bituminous conglomerates or recycled bituminous material or mixed materials containing at least one part of materials containing bitumen, in which the at least one dryer is made up of at least one first dryer portion and of a second dryer portion (4") which are arranged one after the other with the interposition of a hot air passage compartment between the first dryer portion and the second dryer portion (4"), in which the material advances within the first dryer portion according to a direction of advancement of the material in the first dryer portion and in which the material advances within the second dryer portion (4") according to a direction of advancement of the material in the second dryer portion (4"), and further in which the first dryer portion is provided with said burner generating drying heat for the materials present within the first dryer portion and the second dryer portion (4") is devoid of a respective burner intended for the generation of heat for drying the materials which are present within the second dryer portion (4"), the whole drying heat of the materials which are present within the second dryer portion (4") being generated by means of said burner of the first dryer portion said heat being transferred to said second dryer portion (4") by means of a hot airflow oriented from the first dryer portion provided with the burner towards the second dryer portion (4"), characterized in that the first dryer portion is provided with a passage putting in communication the first dryer portion with the second dryer portion (4") generating a preferential path for the hot airflow for heating the material of the second dryer portion (4") and constituting a bypass passage with respect to said hot air passage compartment between the first dryer portion and the second dryer portion (4"), said passage defining an external flow zone of hot airflow which is located between an external surface of the passage and an internal surface of the first dryer portion, the external flow zone being in communication with the air passage compartment, adjustable sealing means (44, 50, 51) being provided which are adjustable into at least three configurations: - a first configuration in which the sealing means (44, 50, 51) leave at least partially open said passage and completely close the flow communication between the external flow zone and the second dryer portion (4"); - a second configuration in which the sealing means (44, 50, 51) completely close said passage and completely close the flow communication between the external flow zone and the second dryer portion (4"); - a third configuration in which the sealing means (44, 50, 51) leave at least partially open said passage and leave at least partially open the flow communication between the external flow zone and the second dryer portion (4"). - at least one dryer for drying materials to be treated wherein the at least one dryer is provided with a burner generating drying heat for the materials to be treated by means of at least one flame of the burner, obtaining treated materials; - a mixer for mixing at least the treated materials; - a control unit; - a first configuration in which the sealing means (44, 50, 51) leave at least partially open said passage and completely close the flow communication between the external flow zone and the second dryer portion (4"); - a second configuration in which the sealing means (44, 50, 51) completely close said passage and completely close the flow communication between the external flow zone and the second dryer portion (4"); - a third configuration in which the sealing means (44, 50, 51) leave at least partially open said passage and leave at least partially open the flow communication between the external flow zone and the second dryer portion (4").