Concrete sludge recycling and recovery process

Abstract

The concrete sludge recycling and recovery process comprises a production step consisting of obtaining a sludge from the concrete sludge with a fines concentration above a first predetermined concentration value and an aggregates concentration below a second predetermined concentration value; a homogenization step consisting of homogenizing the sludge obtained in the production step; a conveying step consisting of conveying the homogenized sludge to at least one concrete production unit; and a utilization step consisting of using the homogenized sludge as a raw material for the manufacture of concrete. Figure 1

Description

Title of the invention: Process for recycling and recovering value from concrete sludge. Technical field

[0001] The present invention relates to a process for recycling and recovering concrete sludge, and more particularly concrete sludge from concrete manufacturing plants. State of the art

[0002] A concrete batching plant, also called a concrete plant, is designed to produce concrete in very large quantities and includes, in particular, a mixing device configured to mix the various constituent materials of the concrete to be produced. The concrete produced in the mixing device is generally transported to a construction site using a mixer truck, also called a concrete mixer truck.

[0003] To prevent fouling of the mixing device in the concrete plant, regular washing of the mixing device is required. Similarly, regular washing of the rotating drums of the mixer trucks is also required.

[0004] For environmental reasons, the wash water from a concrete plant and mixer trucks must be recycled. Generally, this wash water is conveyed to a settling basin where the aggregates and cement slurry contained in the wash water settle by gravity to the bottom of the settling basin.

[0005] The concrete sludge formed from these settled aggregates and laitance is then cleaned and stored in a storage tank, such as a storage skip or a storage pit, at the concrete plant. Returned concrete from mixer trucks and defective or unsold concrete produced by the concrete plant are also stored in such a storage tank.

[0006] Periodically or not, the contents of the storage bin are evacuated to a waste storage facility, such as a quarry or a landfill, where they are buried in the ground.

[0007] One disadvantage of such a concrete manufacturing plant is that the costs related to transporting concrete sludge to a waste storage center and burying concrete sludge in the waste storage center are relatively high. Summary of the invention

[0008] The present invention aims to remedy this drawback.

[0009] The technical problem underlying the invention therefore consists of providing a process for recycling and recovering concrete sludge that is economical and ecological, while ensuring optimal recovery of concrete sludge.

[0010] To this end, the present invention relates to a process for recycling and recovering value from concrete sludge, and preferably from concrete sludge originating from at least one concrete manufacturing plant, comprising the following steps:

[0011] - a production step consisting of obtaining, from the concrete slurries, a slurry, and in particular a pasty sludge, having a concentration of fines which is greater than a first predetermined concentration value and a concentration of aggregates, having dimensions greater than a predetermined value, which is less than a second predetermined concentration value,

[0012] - a homogenization step consisting of homogenizing the mud obtained during the obtaining stage,

[0013] - a conveying step consisting of conveying the homogenized sludge to the minus one concrete production unit, and

[0014] - a usage step consisting of using the homogenized sludge as raw material for the manufacture of concrete.

[0015] Such a configuration of the recycling and recovery process according to the present invention, and in particular the homogenization step, makes it possible to combat the thixotropic properties of the fine-laden sludge obtained during the obtaining step (and in particular to avoid hardening of the sludge), and thus to ensure easy conveyance of the fine-laden sludge to at least one concrete production unit, for use as a raw material for the manufacture of concrete.

[0016] Thus, the configuration of the recycling and recovery process according to the present invention makes it possible on the one hand to considerably reduce the quantity of material that must be transferred to a conventional recycling channel (i.e. to be buried in the ground), and therefore the operating costs of a concrete manufacturing plant, on the other hand to recover value from concrete sludge.

[0017] In the present, "concrete sludge" means, in particular, wash water from mixing equipment in concrete plants, concrete returns from mixer trucks, wash water from rotary tanks and chutes of mixer trucks, the contents of storage tanks intended to store concrete returns from concrete plants, defective or unsold concrete that has been produced by concrete plants, and solidified concrete that has been cleaned in settling basins of concrete plants.

[0018] The recycling and recovery process according to the present invention may further have one or more of the following characteristics, taken alone or in combination.

[0019] According to one embodiment of the invention, the first predetermined concentration value is between 30 and 70% as a percentage by weight. Thus, the sludge obtained during the production step has a concentration of fines, as a percentage by weight, greater than 30% and less than 70%, and for example a concentration of fines, as a percentage by weight, of the order of 50%.

[0020] According to one embodiment of the invention, the mud obtained during the obtaining step has a water concentration, as a percentage by weight, greater than 30% and less than 70%.

[0021] According to one embodiment of the invention, the water loaded with fines has a concentration of fines of between 5 and 20%, as a percentage by weight, and for example of the order of 10%, and therefore a concentration of water of between 80 and 95%, as a percentage by weight, and for example of the order of 90%.

[0022] According to one embodiment of the invention, the homogenization step includes an introduction step consisting of introducing the mud, obtained during the obtaining step, into a storage tank of a homogenization device, such as an agitator hopper, and a movement step consisting of moving the mud contained in the storage tank so as to homogenize said mud.

[0023] According to one embodiment of the invention, the storage tank has a storage capacity of at least 3m3, and therefore of at least 6 tonnes of sludge.

[0024] According to one embodiment of the invention, the homogenization apparatus comprises a sludge introduction hopper opening into the storage tank. Thus, the introduction step consists of introducing the sludge, obtained during the production step, into the storage tank via the sludge introduction hopper. Advantageously, the sludge introduction hopper is adapted to allow the introduction of sludge into the storage tank via a loader bucket, and therefore has a minimum width of at least 2.5 m.

[0025] According to one embodiment of the invention, the homogenizing device comprises a movable protective cover between a covering position in which the protective cover covers the sludge introduction hopper and prevents the introduction of sludge into the storage tank, and a release position in which the protective cover releases the sludge introduction hopper and allows the introduction of sludge into the storage tank.

[0026] According to one embodiment of the invention, the sludge introduction hopper of the homogenizing device comprises a hopper grid. Advantageously, the hopper grid is configured to be inclined with respect to the horizontal.

[0027] According to one embodiment of the invention, the hopper grid is vibrating.

[0028] According to one embodiment of the invention, the starting step is carried out by a drive device equipping the homogenizing apparatus, the drive device comprising a drive shaft disposed in the storage tank, and for example at a distance from the bottom wall of the storage tank and is for example located approximately halfway up the storage tank, and carrying a plurality of mixing elements, and a drive motor, such as an electric motor, configured to drive the drive shaft in rotation around an axis of rotation so as to be able to stir the slurry contained in the storage tank.

[0029] According to one embodiment of the invention, the drive motor is configured to drive the drive shaft in rotation at a rotational speed of between 50 and 60 revolutions per minute.

[0030] According to one embodiment of the invention, the homogenizing device includes a drain hatch located in a lower part of the storage tank.

[0031] According to one embodiment of the invention, the homogenization device includes a hygrometric sensor configured to measure the hygrometry level of the sludge contained in the storage tank.

[0032] According to one embodiment of the invention, the homogenizing device includes a weighing system configured to determine the mass of sludge contained in the storage tank.

[0033] According to one embodiment of the invention, the homogenizing apparatus includes a sludge evacuation opening through which the homogenized sludge is able to be evacuated out of the homogenizing apparatus.

[0034] According to one embodiment of the invention, the homogenizing device comprises a screw conveyor disposed in a lower part of the storage tank and a drive unit configured to rotate the screw conveyor, the screw conveyor being configured to move the homogenized sludge towards the sludge discharge opening.

[0035] According to one embodiment of the invention, the conveying step is carried out using a conveying device configured to convey the mud homogenized by the homogenizing device to at least one concrete production unit.

[0036] According to one embodiment of the invention, at least one concrete production unit comprises a mixer truck and / or a component of a concrete manufacturing plant.

[0037] According to one embodiment of the invention, the conveying device is configured to convey the homogenized slurry to an aggregate weighing device, such as a weighing belt, an aggregate scale or a skip weigher, of a concrete manufacturing plant, or directly into a concrete mixer of the concrete manufacturing plant.

[0038] According to one embodiment of the invention, the conveying device comprises a pump, such as a positive displacement pump (for example a piston pump, a peristaltic pump or an eccentric screw pump) or a centrifugal pump, fluidly connected to the mud discharge opening of the homogenizing device, and a mud injection circuit fluidly connected to a discharge port of the pump and configured to convey homogenized mud, from the homogenizing device, to at least one concrete production unit.

[0039] According to one embodiment of the invention, the slurry injection circuit comprises at least one pipeline configured to inject homogenized slurry, from the homogenization unit, into a mixer truck and / or into a component of a concrete batching plant. This at least one pipeline may, for example, have a length greater than 10 m, advantageously greater than 20 m, and, for example, up to 30 m.

[0040] According to one embodiment of the invention, at least one pipe has an internal diameter between 50 mm and 60 mm.

[0041] According to one embodiment of the invention, the mud injection circuit comprises a first pipeline configured to inject homogenized mud into a mixer truck, and a second pipeline configured to inject homogenized mud into a component of a concrete manufacturing plant.

[0042] According to one embodiment of the invention, the conveying step includes a control step consisting of controlling the operation of the pump in a first direction of rotation so as to convey homogenized sludge, coming from the homogenization device, into the sludge injection circuit and to at least one concrete production unit, and the recycling and recovery process includes an emptying step consisting of controlling the operation of the pump in a second direction of rotation, opposite to the first direction of rotation, so as to convey the homogenized sludge, contained in the sludge injection circuit, to the storage tank, and thus to empty the sludge injection circuit.

[0043] According to one embodiment of the invention, the conveying step consists of conveying, at each mud injection cycle, a predetermined quantity of mud to at least one concrete production unit.

[0044] According to one embodiment of the invention, the conveying step includes a control step consisting of controlling the operation of the device conveying, and for example of the pump, so as to convey, at each mud injection cycle, a predetermined quantity of mud to at least one concrete production unit.

[0045] According to another embodiment of the invention, the conveying device comprises a belt conveyor, a screw conveyor, a bucket elevator, an extruder, a suction conveying device, or even a cable or rail wagon.

[0046] According to one embodiment of the invention, the homogenizing device comprises an electronic control unit configured to control the operation of the homogenizing device, and in particular the drive mechanism. The drive mechanism can, for example, be activated continuously or intermittently.

[0047] According to one embodiment of the invention, the electronic control unit is configured to control the operation of the conveying device, and for example the pump, so as to convey, at each mud injection cycle, a predetermined quantity of mud to at least one concrete production unit.

[0048] According to one embodiment of the invention, the recycling and recovery process includes a separation step carried out prior to the production step, consisting of separating aggregates contained in the concrete sludge and having dimensions greater than the predetermined value, from the water laden with fines contained in the concrete sludge. Such a separation step makes it possible, in particular, to separate the aggregates contained in the concrete sludge, with a view to reusing said aggregates for the manufacture of concrete.

[0049] Advantageously, the obtaining step consists of obtaining a sludge having a fines concentration greater than the first predetermined concentration value and an aggregates concentration less than the second predetermined concentration value, from the water loaded with fines which was separated during the separation step.

[0050] According to one embodiment of the invention, the obtaining step includes a decantation step consisting of decanting the water loaded with fines which was separated during the separation step.

[0051] According to one embodiment of the invention, the settling step is carried out in a settling basin configured to be supplied with water loaded with fines.

[0052] According to one embodiment of the invention, the recycling and recovery process includes a dredging step consisting of dredging the decanted sludge in the settling basin.

[0053] According to one embodiment of the invention, the obtaining step includes a transfer step consisting of transferring the settled sludge into a storage container, such as that a storage tank, and a storage step consisting of storing the settled sludge for a predetermined period of time, for example for several days, in the storage container.

[0054] According to one embodiment of the invention, the predetermined value is between 300 and 700 pm, and advantageously between 400 and 600 pm, and is for example equal to about 500 pm.

[0055] According to one embodiment of the invention, the recycling and recovery process includes a conveying step consisting of conveying, for example by gravity, the water loaded with fines, which has been separated during the separation step, into an agitation basin, and an agitation step consisting of agitating the water loaded with fines contained in the agitation basin, the conveying and agitation steps being carried out prior to the obtaining step, and for example prior to the decantation step.

[0056] According to one implementation method of the recycling and recovery process, the recycling and recovery process includes a feeding step consisting of supplying the settling basin with water loaded with fines from the stirring basin.

[0057] According to one embodiment of the invention, the separation step includes a step of washing the concrete sludge.

[0058] According to one embodiment of the invention, the separation step is carried out using a concrete recycler.

[0059] According to one embodiment of the invention, the separation step includes an introduction step consisting of introducing concrete sludge into an internal reservoir of the concrete recycler via an introduction hopper of the concrete recycler, a first evacuation step consisting of evacuating the water laden with fines out of the concrete recycler and a second evacuation step consisting of evacuating the aggregates out of the concrete recycler.

[0060] According to one embodiment of the recycling and recovery process, the concrete sludge washing step is carried out in the internal tank of the concrete recycler. Advantageously, the concrete recycler is equipped with a water supply port that is fluidly connected to the internal tank.

[0061] According to one implementation method of the recycling and recovery process, the aggregates discharged from the concrete recycler fall by gravity onto the ground or into an aggregate storage container.

[0062] According to one embodiment of the invention, the recycling and recovery process further comprises a screening step of the concrete sludge which is carried out prior to the separation step and which consists of separating concrete blocks, which have dimensions greater than a predetermined dimension, from the sludge of concrete. Such a screening step avoids the introduction of large concrete blocks into the separation device configured to separate aggregates, and therefore limits the risks of clogging or breakage of this separation device.

[0063] According to one implementation method of the recycling and recovery process, the predetermined dimension is between 10 and 30 mm, advantageously between 15 and 25 mm, and is for example equal to about 20 mm.

[0064] According to one embodiment of the invention, the screening step is carried out using a screening bucket.

[0065] According to one embodiment of the invention, the recycling and recovery process includes a step of crushing the separated concrete blocks.

[0066] According to one embodiment of the invention, the recycling and recovery process includes a use step consisting of using the crushed concrete blocks for the construction of buildings, such as buildings, road infrastructure, or urban developments of all types. These provisions further improve the recovery of concrete sludge.

[0067] According to one embodiment of the invention, the recycling and recovery process includes a collection step consisting of collecting concrete sludge from different concrete plants. These arrangements make it possible to centralize the treatment of concrete sludge in a single concrete plant.

[0068] According to one embodiment of the invention, the recycling and recovery process includes a use step consisting of using the separated aggregates as a raw material for the manufacture of concrete.

[0069] According to one embodiment of the invention, the recycling and recovery process includes a utilization step consisting of using a portion of the water loaded with fines, which was separated during the separation step, as a raw material for the manufacture of concrete.

[0070] According to one embodiment of the invention, the recycling and recovery process includes a use step consisting of using at least part of the clarified water from the decantation step as a raw material for the manufacture of concrete.

[0071] According to one embodiment of the invention, the second predetermined concentration value is, as a percentage by weight, less than 20%, and advantageously less than 5%, and for example, approximately 0%. Thus, the sludge obtained during the production step has an aggregate concentration, as a percentage by weight, of less than 20%, and advantageously less than 5%, and for example, approximately 0%. Brief description of the figures

[0072] The invention will be well understood with the aid of the following description with reference to the attached schematic drawings representing, by way of non-limiting example, one embodiment of a concrete manufacturing plant enabling the implementation of the recycling and recovery process according to the present invention.

[0073] [Fig.l] is a schematic view of a concrete manufacturing plant enabling the implementation of a recycling and recovery process according to the present invention;

[0074] [Fig.2] is a perspective view of a homogenizing apparatus belonging to the concrete manufacturing plant of [Fig.1]. Detailed description

[0075] Fig. 1 represents a concrete manufacturing plant 2 comprising a treatment unit 3 configured to separate aggregates, contained in concrete slurries, from the water laden with fines contained in the concrete slurries, and a settling unit 4 configured to settle the water laden with fines that has been separated from the aggregates.

[0076] The treatment unit 3 more particularly comprises a concrete recycler 5 including an internal reservoir 6, an inlet hopper 7 opening into the internal reservoir 6 and configured to allow the introduction of concrete slurries into the internal reservoir 6, a first discharge opening 8 through which separate aggregates 9 are intended to be discharged from the concrete recycler 5 and a second discharge opening 10 through which water laden with fines is intended to be discharged from the concrete recycler 5. The aggregates 9 discharged from the concrete recycler 5 can, for example, fall by gravity onto the ground or into an aggregate storage container.

[0077] According to one embodiment of the invention, the treatment unit 3 can be provided with a water supply orifice fluidly connected to the internal reservoir 6 and configured to allow the introduction of water into the internal reservoir 6.

[0078] The settling unit 4 includes in particular an agitation basin 11 into which the water laden with fines from the concrete recycler 5, and more particularly from the second discharge opening 10, is intended to be conveyed and agitated, and a settling basin 12 configured to be supplied with water laden with fines from the agitation basin 11, for example by means of a feed pump.

[0079] The concrete manufacturing plant 2 further includes a storage container 13, such as a storage tank, which is open at the top and which is configured to store decanted sludge from the settling basin 12.

[0080] The concrete manufacturing plant 2 further includes a homogenizing device 14, such as an agitator hopper, configured to homogenize sludge from the storage container 13.

[0081] The homogenizing apparatus 14 more particularly comprises a storage tank 15, a sludge introduction hopper 16 opening into the storage tank 15 and configured to allow the introduction of sludge into the storage tank 15, for example via a loader bucket, and a sludge discharge opening 17 through which homogenized sludge is suitable for discharge from the homogenizing apparatus 14. Advantageously, the storage tank 15 has a storage capacity of at least 3m3, and is therefore suitable for holding at least 6 tonnes of sludge, and the sludge introduction hopper 16 has a minimum width of at least 2.5 m.

[0082] According to the embodiment shown in the figures, the sludge introduction hopper 16 comprises a hopper grid 18, which is, for example, vibrating. Advantageously, the hopper grid 18 is configured to be inclined relative to the horizontal when the homogenizing device 14 rests on a horizontal surface.

[0083] The homogenizing apparatus 14 also includes a drive device 19 comprising a drive shaft 20 disposed in the storage tank 15 and carrying a plurality of mixing elements 21, and a drive motor 22, such as an electric motor, configured to drive the drive shaft 20 in rotation about an axis of rotation extending coaxially with the central longitudinal axis of the drive shaft 20, so as to be able to stir the slurry contained in the storage tank 15. Advantageously, the drive shaft 20 is located substantially at mid-height of the storage tank 15, and the axis of rotation is configured to be substantially horizontal when the homogenizing apparatus 14 rests on a horizontal surface.The drive motor 22 can, for example, be configured to rotate the drive shaft 20 at a rotational speed of between 50 and 60 revolutions per minute, and can, for example, be located outside the storage tank 15.

[0084] As shown in [Fig.2], the homogenizing apparatus 14 also includes a screw 23 disposed in a lower part of the storage tank 15 and a drive unit 24 disposed outside the storage tank 15 and configured to drive the screw 23 in rotation about a screw rotation axis which is substantially parallel to the rotation axis of the drive shaft 20. The screw 23 is more particularly configured to move the homogenized sludge towards the sludge discharge opening 17.

[0085] Advantageously, the homogenizing device 14 can be equipped with a protective cover (not shown in the figures) movable between a covering position in which the protective cover covers the sludge introduction hopper 16 and prevents the introduction of sludge into the storage tank 15, and a release position in which the protective cover releases the sludge introduction hopper 16 and allows the introduction of sludge into the storage tank 15.

[0086] The homogenizing apparatus 14 may further include a drain hatch (not shown in the figures) located in a lower part of the storage tank 15.

[0087] The homogenizing apparatus 14 may also include a weighing system configured to determine the mass of sludge contained in the storage tank 15. The weighing system may, for example, be equipped with load cells 25 each fixed to a respective foot of the homogenizing apparatus 14.

[0088] Advantageously, the homogenizing device 14 also includes a hygrometric sensor (not shown in the figures) configured to measure the hygrometry level of the sludge contained in the storage tank 15.

[0089] The concrete manufacturing plant 2 also includes a conveying device 26 configured to convey the slurry homogenized by the homogenizing device 14 to at least one concrete production unit 27, such as a mixer truck and / or a component of the concrete manufacturing plant 2. The component of the concrete manufacturing plant 2 may, for example, be an aggregate weighing device (such as a weighing conveyor, an aggregate scale or a skip weigher) or a concrete mixer.

[0090] According to the embodiment shown in the figures, the conveying device 26 comprises a pump 28, such as a positive displacement pump (for example a piston pump, a peristaltic pump or an eccentric screw pump) or a centrifugal pump, fluidly connected to the mud discharge opening 17 of the homogenizing device 14, and a mud injection circuit 29 fluidly connected to a discharge port of the pump 28 and configured to convey homogenized mud, from the homogenizing device 14, to at least one concrete production unit 27.

[0091] The mud injection circuit 29 may for example include a first pipeline configured to inject homogenized mud, from the homogenizing device 14, into a mixer truck, and a second pipeline configured to inject homogenized mud, from the homogenizing device 14, into a component of the concrete manufacturing plant 2.

[0092] The concrete manufacturing plant 2 further comprises an electronic control unit 31 configured to control the operation of, in particular, the homogenizing device 14 and the conveying device 26, and in particular the drive device 19 and the pump 28. Advantageously, the electronic control unit 31 is configured to activate the drive device 19 continuously or intermittently, and is configured to control the operation of the conveying device 26, and for example the pump 28, so as to convey, at each mud injection cycle, a predetermined quantity of mud to at least one concrete production unit 27.

[0093] A process for recycling and recovering value from concrete sludge, which is partly implemented by concrete plant 2, will now be described. Such a recycling and recovery process comprises the following steps:

[0094] - a separation step carried out using the concrete recycler 5 and consisting of to separate aggregates, contained in concrete sludge and having dimensions greater than a predetermined value (which is advantageously between 400 and 600 pm, and for example equal to about 500 pm), from the water laden with fines which is contained in the concrete sludge,

[0095] - a production step consisting of obtaining, from water laden with fines which has during the separation stage, a sludge, and more particularly a pasty sludge, having a concentration of fines which is greater than a first predetermined concentration value (and advantageously a concentration of fines between 30 and 70% as a percentage by weight, and for example a concentration of fines, as a percentage by weight, of the order of 50%) and a concentration of aggregates, having dimensions greater than the predetermined value, which is less than a second predetermined concentration value (and advantageously a concentration of aggregates, as a percentage by weight, less than 20%, and further advantageously less than 5%, and for example of about 0%),

[0096] - a homogenization step carried out at least in part using the apparatus homogenization step 14, which consists of homogenizing the mud obtained during the production step,

[0097] - a conveying step carried out using the conveying device 26 and consisting to convey the homogenized slurry to at least one concrete production unit 27 belonging to the concrete manufacturing plant 2, and

[0098] - a usage step consisting of using the homogenized sludge as raw material for the manufacture of concrete.

[0099] According to one implementation method of the recycling and recovery process, the separation step comprises the following steps:

[0100] - an introductory step consisting of introducing concrete slurries into the reservoir internal 6 of the concrete recycler 5 via the feed hopper 7 fitted to the latter, for example using a loader bucket,

[0101] - a washing step consisting of washing the concrete sludge contained in the internal reservoir 6 with water introduced into the internal reservoir 6 via the water supply port,

[0102] - a first evacuation step consisting of evacuating the water laden with fines out of the concrete recycler 5 via the second discharge opening 10, and

[0103] - a second evacuation step consisting of evacuating, for example by gravity, the separated aggregates 9 out of the concrete recycler 5 via the first discharge opening 8.

[0104] According to one implementation method of the recycling and recovery process, the recycling and recovery process comprises the following steps which are carried out prior to the production step:

[0105] - a conveying step consisting of conveying, for example by gravity or to with the help of a feed pump, the water laden with fines, which was discharged from the concrete recycler 5, into the agitation basin 11,

[0106] - an agitation step consisting of agitating the water laden with fines contained in the agitation basin 11, and

[0107] - a feeding step consisting of supplying the settling basin 12 with water loaded with fines from the agitation basin 11, for example by overflow from the agitation basin 11.

[0108] According to one implementation method of the recycling and recovery process, the production step comprises the following steps:

[0109] - a settling step carried out in the settling basin 12 and consisting of to allow the water laden with fines contained in the basin to settle in settling basin 12,

[0110] - a cleaning step consisting of cleaning, for example using a bucket of loader, the settled sludge in settling basin 12,

[0111] - a transfer step consisting of transferring, for example using a bucket, a loader, the settled sludge in storage container 13, and

[0112] - a storage step consisting of storing the settled sludge for a period of predetermined time, and for example for several days, in the storage container 13, so as to obtain the desired pasty slurry.

[0113] According to one implementation method of the recycling and recovery process, the homogenization step comprises the following steps:

[0114] - an introduction step consisting of introducing the mud, obtained during the step of obtaining, in the storage tank 15 of the homogenization unit 14 via the sludge introduction hopper 16 equipping the latter, and

[0115] - a starting step carried out by the starting device 19 equipping the homogenization device 14 and consisting of moving the sludge contained in the storage tank 15 in order to homogenize said sludge.

[0116] According to one embodiment of the invention, the conveying step includes a control step consisting of controlling the operation of the conveying device 26, and more particularly of the pump 28, so as to convey, at each mud injection cycle, a predetermined quantity of mud to at least one concrete production unit 27.

[0117] According to one embodiment of the recycling and recovery process, the control step consists of controlling the operation of the pump 28 in a first direction of rotation so as to convey a predetermined quantity of sludge, from the homogenizing device 14, into the sludge injection circuit 29 and to at least one concrete production unit 27, and the recycling and recovery process includes a draining step consisting of controlling the operation of the pump 28 in a second direction of rotation, opposite to the first direction of rotation, so as to convey the homogenized sludge, contained in the sludge injection circuit 29, to the storage tank 15, in order to drain the sludge injection circuit 29.

[0118] According to one implementation method of the recycling and recovery process, the recycling and recovery process further comprises:

[0119] - a use step consisting of using the aggregates separated during the step of separation as a raw material for the manufacture of concrete,

[0120] - a use step consisting of using a portion of the water laden with fines, which was separated during the separation stage, as a raw material for the manufacture of concrete.

[0121] - a use step consisting of using at least part of the clarified water resulting from the settling stage (for example obtained by overflow from the settling basin) as a raw material for the manufacture of concrete.

[0122] According to one embodiment of the recycling and recovery process, the latter further comprises a screening step of the concrete sludge, which is carried out prior to the separation step and consists of separating concrete blocks, which have dimensions exceeding a predetermined size, from the concrete sludge. Such a screening step, which can be carried out using a screening bucket, avoids the introduction of large concrete blocks into the concrete recycler 5. The predetermined dimension can be between 10 and 30 mm, advantageously between 15 and 25 mm, and is for example equal to about 20 mm.

[0123] According to one implementation of the recycling and recovery process, the latter comprises a crushing step of the concrete blocks separated during the screening step, and a use step consisting of using the crushed concrete blocks for the construction of structures, such as buildings, road infrastructure, or urban developments of all types. These provisions further improve the recovery of concrete sludge.

[0124] According to one implementation method of the recycling and recovery process, the latter also includes a collection step consisting of collecting concrete sludge from different concrete batching plants. These provisions make it possible to centralize the treatment of concrete sludge in a single concrete batching plant, and therefore to limit the costs of treating this concrete sludge.

[0125] According to one embodiment of the recycling and recovery process, the conveying device 26 could include, instead of the pump 28 and the sludge injection circuit 29, a belt conveyor, a screw conveyor, a bucket elevator, an extruder, a suction conveying device, or even a cable or rail wagon.

[0126] According to one variant of the recycling and recovery process implementation, the separation step could be carried out using a settling device comprising, for example, several successive settling basins.

[0127] As can be understood, the invention is not limited to the methods of implementation of this recycling and recovery process described above by way of example, but on the contrary encompasses all the variant embodiments.

Claims

Demands

1. A process for recycling and recovering value from concrete sludge comprising the following steps: - a production step consisting of obtaining, from the concrete sludge, a sludge having a concentration of fines which is greater than a first predetermined concentration value and a concentration of aggregates, having dimensions greater than a predetermined value, which is less than a second predetermined concentration value, - a homogenization step consisting of homogenizing the sludge obtained during the production step, - a conveying step consisting of conveying the homogenized sludge to at least one concrete production unit (27), and - a utilization step consisting of using the homogenized sludge as a raw material for the manufacture of concrete.

2. A recycling and recovery process according to claim 1, wherein the homogenization step includes an introduction step consisting of introducing the sludge, obtained during the obtaining step, into a storage tank (15) of a homogenizing apparatus (14), and a movement step consisting of moving the sludge contained in the storage tank (15) so as to homogenize said sludge.

3. Recycling and recovery process according to claim 2, wherein the homogenizing apparatus (14) comprises a sludge introduction hopper (16) opening into the storage tank (15).

4. A recycling and recovery process according to claim 2 or 3, wherein the movement step is carried out by a movement device (19) equipping the homogenizing apparatus (14), the movement device (19) comprising a drive shaft (20) disposed in the storage tank (15) and carrying a plurality of mixing elements (21), and a drive motor (22) configured to drive the drive shaft (20) in rotation around an axis of rotation so as to be able to stir the sludge contained in the storage tank (15).

5. A recycling and recovery process according to any one of claims 2 to 4, wherein the homogenizing apparatus (14) has a sludge discharge opening (17) through which the homogenized sludge is able to be discharged from the homogenizing apparatus (14).

6. A recycling and recovery process according to claim 5, wherein the homogenizing apparatus (14) comprises a screw (23) disposed in a lower part of the storage tank (15) and a drive unit (24) configured to rotate the screw (23), the screw (23) being configured to move the homogenized sludge towards the sludge discharge opening (17).

7. A recycling and recovery process according to any one of claims 1 to 6, wherein the conveying step is carried out using a conveying device (26) configured to convey the sludge homogenized by the homogenizing apparatus (14) to at least one concrete production unit (27).

8. A recycling and recovery process according to claims 5 and 7, wherein the conveying device (26) comprises a pump (28) fluidly connected to the sludge discharge opening (17) of the homogenizing apparatus (14), and a sludge injection circuit (29) fluidly connected to a discharge port of the pump (28) and configured to convey homogenized sludge, from the homogenizing apparatus (14), to at least one concrete production unit (27).

9. A recycling and recovery process according to claim 8, wherein the conveying step includes a control step consisting of controlling the operation of the pump (28) in a first direction of rotation so as to convey homogenized sludge, from the homogenizing device (14), into the sludge injection circuit (29) and to at least one concrete production unit (27), and wherein the recycling and recovery process includes a draining step consisting of controlling the operation of the pump (28) in a second direction of rotation, opposite to the first direction of rotation, so as to convey the homogenized sludge, contained in the sludge injection circuit (29), to the storage tank (15), and thus to drain the sludge injection circuit (29).

10. A recycling and recovery process according to any one of claims 7 to 9, wherein the conveying step consists of conveying, at each sludge injection cycle, a predetermined quantity of sludge to at least one concrete production unit (27).

11. A recycling and recovery process according to any one of claims 1 to 10, comprising a separation step carried out prior to the production step and consisting of separating aggregates, contained in concrete sludge and having dimensions greater than the predetermined value, from the water laden with fines which is contained in the concrete sludge.

12. A recycling and recovery process according to claim 11, wherein the obtaining step includes a settling step consisting of settling the water loaded with fines which was separated during the separation step.

13. A recycling and recovery process according to claim 12, wherein the settling step is carried out in a settling basin (12) configured to be supplied with water loaded with fines.

14. Recycling and recovery process according to claim 13, wherein the obtaining step includes a dredging step consisting of dredging the decanted sludge in the settling basin (12).

15. A recycling and recovery process according to claim 14, wherein the obtaining step includes a transfer step consisting of transferring the settled sludge into a storage container (13), and a storage step consisting of storing the settled sludge for a predetermined period of time in the storage container (13).

16. A recycling and recovery process according to any one of claims 11 to 15, wherein the predetermined value is between 300 and 700 pm.

17. A recycling and recovery process according to any one of claims 11 to 16, comprising a conveying step consisting of conveying the water laden with fines, which was separated in the separation step, into an agitation basin (11), and an agitation step consisting of agitating the water laden with fines contained in

18. the stirring basin (11), the conveying and stirring steps being carried out prior to the obtaining step. Recycling and recovery process according to any one of claims 1 to 17, comprising a collection step consisting of collecting concrete sludge from different concrete manufacturing plants.

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