Process of recycling a bituminous waste product such as a waste bituminous membrane product
A process of recycling a bituminous product or a bituminous membrane product contacting reinforcement layers. Collecting the waste bituminous products and sorting it in a series of waste bituminous product batches. At least one grinding step of each batch in each series forms a fine ground batch. The fine ground batch is introduced into a recycling unit wherein the fine ground batch is heated and melted and collected as a melted product. The melted product is fed into a mixing tank having a predetermined volume containing fresh carrier.
1. A process of recycling a bituminous product, or a bituminous membrane product containing reinforcement layers, the process comprising the steps of:
collecting waste bituminous products, or waste bituminous membrane products containing bituminous layers and reinforcement layers and sorting the waste bituminous products in a series of n waste bituminous product batch(es);
at least one grinding step of each batch of said series of n waste bituminous product batch(es) or of a mixture of n waste bituminous product batch(es), thereby forming a fine ground batch;
introducing said fine ground batch into a recycling unit having at least a rotor and a stator and a micronization chamber, said fine ground batch being heated and melted by shear strength upon an operation of the stator, rotor and micronization chamber and collecting a melted product; and
feeding said melted product in a mixing tank having a predetermined volume containing fresh carrier at a level comprised between 25 and 75w %, with respect to the predetermined volume, and at a residence temperature between 160 and 200° C., said mixing tank being continuously agitated with a horizontal screw having mixing blades, said melted product being fed in said mixing tank until a volume of the melted product is comprised between 25 and 75w %, with respect to the predetermined volume to provide a recycled bitumen at a temperature of 180° C. for pumpability and having a predefined viscosity between 500 and 45000 cPS, wherein said at least one grinding step comprises:
a first grinding of each batch of said series of n waste bituminous product batch(es) in a knife shredder for reducing a size of each batch into a first shredded batch having a mean particle size distribution between 20 and 50 cm;
a second grinding of each first shredded batch in a rotor granulator where each first shredded batch is reduced in size to a first crushed batch having a mean particle size distribution between 5 and 25 cm; and
a third grinding of each first crushed batch in a rotor granulator where each first crushed batch is reduced in size to a first ground batch having a mean particle size distribution between 20 and 50 mm.
2. The process according to claim 1 , wherein before being fed to said recycling unit, said fine ground batch is conveyed on a vibrating sieve to collect a fine ground batch substantially depleted from dust and particles having a particle size d100 lower than 8 mm.
3. The process according to claim 1 , wherein, before being fed to said recycling unit, said fine ground batch undergoes a step of separating metal pieces from non-metal pieces by application of Foucault current to said fine ground batch and collecting a fine ground mixture substantially depleted from metal pieces.
4. The process according to claim 1 , wherein the recycled bitumen is further withdrawn by pumping in batches and filtrated in a bag filter, before or after being stored in a storage tank.
5. The process according to claim 1 , wherein said fine ground batch is melted at a temperature between 110° C. and 260° C.