Treatment plant with optimised densimetric sorting and related treatment process

A method for treating a primary mixture (2A) of wastes from household and similar refuse collection, a non-negligible portion of the mass of said primary mixture (2A) of wastes being formed by biodegradable wastes, said primary mixture (2A) of wastes comprising non-biodegradable wastes, said method comprising a step E1 of treating a secondary mixture (2B) of materials obtained from said primary mixture (2A) of wastes, a non-negligible portion of the mass of said secondary mixture (2B) of materials being formed by biodegradable materials, said treatment step E1 comprising the following successive steps:

• an operation O1 in which said secondary mixture (2B) of materials is introduced into a rotary trommel (3) provided with a separation wall (4) with a series of separation through-holes, and said secondary mixture (2B) of materials is separated into a first fraction (5) of materials passing through said separation wall (4) via the series of separation holes and a second residual fraction of materials, the secondary mixture (2B) of materials flowing along said separation wall (4) to be separated thereby,
• an operation O2 in which said first fraction (5) of materials is separated, using a ballistic separation means (8), into at least one first and second subfractions (9, 10) of materials, the first subfraction (9) of materials being formed of materials having an average density lower than the average density of the materials forming the second subfraction (10) of materials, and
• an operation O3 in which a densimetric sorting is applied to each of said first and second subfractions (9, 10) of materials, respectively, using at least one first and second densimetric tables (6, 7), each fed by said ballistic separation means (8) wherein the ballistic separation means (8) implemented in operation O2 comprises:
• an inclined drop ramp (12) comprising, at an upstream end, a ramp portion, called collecting portion (13), that is positioned opposite the separation wall (4) of the trommel (3) to collect said first fraction (5) of materials, and an opposite, downstream end (14) that is positioned above and remote from a feed portion (15) of a conveyor means (11), which is positioned at a lower altitude than a respective altitude of the trommel (3), and
• at least one ballistic distribution flap (16) that defines, on a conveying surface of said conveyor means (11), at least one first area (17) for conveying said first subfraction (9) of materials and a second area (18) for conveying said second subfraction (10) of materials, said conveyor means (11) including an evacuation portion (19) through which the first and second conveying areas (17, 18) each feed said first and second densimetric tables (6, 7), respectively;
• wherein said drop ramp (12) comprises a ramp portion, called acceleration portion (20), that extends said collecting portion (13) up to the downstream end (14) of the drop ramp (12), and whose average inclination is adjustable with respect to the vertical;
• wherein said separation wall (4) extends along a longitudinal axis of extension (A-A′) about which said separation wall (4) is rotatably mounted, said drop ramp (12) extending longitudinally along said longitudinal axis of extension (A-A′) of the separation wall (4);
• and
• wherein the acceleration portion (20) of the drop ramp (12) has an average inclination with respect to the vertical that varies along said longitudinal axis of extension (A-A′) of the separation wall (4);
• and
• wherein an aerobic or anaerobic biological degradation process has been applied to the wastes contained in said primary mixture (2A) of wastes, in order to biodegrade said biodegradable wastes, said secondary mixture (2B) of materials being then formed of all or part of a residual matter resulting from said aerobic or anaerobic biological degradation process.

A plant for treating a primary mixture (2A) of wastes from household and similar refuse collection, a non-negligible portion of the mass of said primary mixture (2A) of wastes being formed by biodegradable wastes, said primary mixture (2A) of wastes comprising non-biodegradable wastes, said treatment plant comprising a unit (1) for treating a secondary mixture (2B) of materials obtained from said primary mixture (2A) of wastes, a non-negligible portion of the mass of said secondary mixture (2B) of materials being formed by biodegradable materials, said treatment unit (1) comprising a rotary trommel (3) provided with a separation wall (4) with a series of separation through-holes for separating the secondary mixture (2B) of materials into a first fraction (5) of materials passing through said separation wall (4) via the series of separation holes and a second residual fraction of materials, the secondary mixture (2B) of materials being intended to flow along said separation wall (4) to be separated thereby, said treatment unit (1) also comprising at least one first and second densimetric tables (6, 7), and a ballistic separation means (8) positioned between said trommel (3) and said densimetric tables (6, 7) to collect said first fraction (5) of materials and feed the first and second densimetric tables (6, 7) with at least one first and second subfractions (9, 10) of materials, respectively, the first subfraction (9) of materials being formed of materials having an average density lower than an average density of the materials forming the second subfraction (10) of materials;

• wherein said treatment unit (1) comprises a conveyor means (11), which is positioned at a lower altitude than a respective altitude of the trommel (3), said ballistic separation means (8) comprising:
• an inclined drop ramp (12) comprising, at an upstream end, a ramp portion, called collecting portion (13), that is positioned opposite the separation wall (4) of the trommel (3) to collect said first fraction (5) of materials, and having an opposite, downstream end (14) that is positioned above and remote from a feed portion (15) of the conveyor means (11);
• at least one ballistic distribution flap (16) that defines, on a conveying surface of said conveyor means (11), at least one first area (17) for conveying said first subfraction (9) of materials and a second area (18) for conveying said second subfraction (10) of materials,
• said conveyor means (11) including an evacuation portion (19), through which the first and second conveying areas (17, 18) are able to feed each of said densimetric tables (6, 7), respectively;
• wherein said drop ramp (12) comprises a ramp portion, called acceleration portion (20), that extends said collecting portion (13) up to the downstream end (14) of the drop ramp (12), and whose average inclination is adjustable with respect to the vertical;
• wherein said separation wall (4) extends along a longitudinal axis of extension (A-A′) about which said separation wall (4) is rotatably mounted, said drop ramp (12) extending longitudinally along said longitudinal axis of extension (A-A′) of the separation wall (4);
• wherein the acceleration portion (20) of the drop ramp (12) has an average inclination with respect to the vertical that varies along said longitudinal axis of extension (A-A′) of the separation wall (4);
• and
• upstream from said treatment unit (1), an aerobic or anaerobic biological degradation unit for applying a biological degradation process to the biodegradable wastes contained in said primary mixture (2A) of wastes, in order to biodegrade said biodegradable wastes and to thus form said secondary mixture (2B) of materials.