FR2760665A1 - Procedure for treating soil pollution - Google Patents

Abstract

The procedure for treating and getting rid of soil pollution comprises the following operations. The selected soil is cut up into squared zones which are analysed for chemical pollution. Batches of polluted earth are assembled as a function of their degree of pollution. Successive batches are treated in the installation by adapting the characteristics of the de-polluting fluids to the characteristics of the batches. Several washing and fragmentation operations enable selecting successive analysis of particles to ensure complete treatment of a part of the initial mass polluted with a specific analysis. The other parts of the material are evacuated for other recycling operations. The treatment installation is easily assembled and dismantled and enables satisfactory treatment of 70% to 80% of soils.

Description

PROCESS AND PLANT FOR TREATMENT
AND DEPOLLUTION OF SOIL
The invention relates to the technical sector of the treatment of polluted soils of all kinds, materials, and their depollution for reclamation.

 The treatment of soil polluted by all materials or chemicals is well known.

 These installations used are very heavy to set up and costly, so that their use is only carried out for large areas or spaces, making it possible to recoup the cost of depollution operations.

 Known installations are complex in that they meet the objective of total soil reprocessing, even if certain sludges are particularly expensive to regenerate.

 Known installations are stationary, so that their removal by successive disassembly-assembly is not envisaged.

 A first goal sought was to design a treatment and pollution control installation that is easy to assemble and disassemble, transportable under all conditions of safety and approval, having regard to the requirements of the Highway Code.

 Another goal sought was to design an installation which allows a satisfactory treatment to depollute at least 70 to 80% of the soils, the rest being treated under other conditions.

 Another goal sought was to design an installation which could be transportable and displaceable allowing the successive assembly-disassembly, thus making it possible to work in depollution on sites of small surfaces resolving most of the needs and at lower cost.

 Another goal sought was to design an autonomous pollution control installation.

 These and other objects will become apparent from the following description.

According to a first characteristic, the process for treating and decontaminating the soil is characterized by the implementation of the following operations
- the selected soil is precut into grid areas which are subject to chemical pollution measurements and analyzes;
- the polluted soil masses are assembled in batches according to their degree and characteristics of pollution;
- batch by batch is treated successively by adapting the characteristics of the fluids participating in the depollution to the characteristics of the batches treated
- Introducing into the treatment plant of polluted materials, successive masses of materials which are combined with one or more projections and distribution of fluids allowing the fragmentation of materials;
- several washing and fragmentation operations are carried out making it possible to select successive particle sizes of particles or pieces of polluted material treated, in order to ensure complete treatment of part of the initial mass of polluted materials with a specific particle size, the other pieces or parts of material being either disposed of for other recycling operations with a view to obtaining additional fragmentation, or being in the form of sludge for another treatment;
- the particles selected at a given particle size are then removed, dried to be reconditioned unpolluted on the treated site.

 According to a first characteristic, the installation comprises a support structure arranged to receive, maintain various components and materials necessary for the process, arranged in successive order for a continuous supply of the polluted materials to be treated in combination with means for dispensing washing fluid. , means of fragmentation, means of filtration, to select and distribute the pieces of material according to their particle size index, means of removal for the masses of materials not selected, said contaminated materials of a determined particle size being removed in a soaking and settling tank for a final selection in order to separate very fine polluted materials in the form of sludge, materials of small particle size for their drying and evacuation to be rested in situ on the initially polluted site.

 According to another characteristic, the installation is remarkable in that it comprises modules transportable on a trailer, each module receiving a part of the hardware components allowing the processing of the materials, at least two of the said modules being established with a platform supporting the component and equipment, said platforms comprising means allowing their lifting and handling to position them either on the trailers for the purpose of moving the installation, or to place them in situ near the depollution site.

To fix the object of the invention illustrated in the figures of the drawings:
- Figure 1 is a schematic view of an area of land to be cleared, gridded in lots for the execution of pollution measurement;
- Figure 2 is a schematic view illustrating the formation of
lots by volume of soil removed from the site to be cleaned up;
- Figure 3 is a schematic view illustrating the installation according to the invention;
- Figure 4 is a top view according to Figure 3;
- Figure 5 is a side view according to Figure 3
- Figure 6 is a view in the form of a block table illustrating the different operating phases of the installation;
- Figures 7a, 7b and 7c are schematic views illustrating the transport of the different modules on trailer (1), the modules constituting the installation.

 In order to make the object of the invention more concrete, it is now described in a nonlimiting manner illustrated in the figures of the drawings.

 It should first of all be recalled that the process for treating polluted soil is carried out as follows with reference to FIG. 1 of the drawings.

 The selected soil is precut into grid areas which are analyzed by measurement using sampling means. We thus define from the chemical analyzes carried out, zones with variable pollution characteristics, making it possible to establish and group together heaps or lots of polluted earth masses (Figure 2). These groupings in batches having been carried out, they are then treated by the installation which is the subject of the invention after having informed the latter of all the chemical characteristics of the pollution observed in the batches treated.

 Said installation is according to the invention established on the basis of transportable modules (A, B, C ...) and which can then be coupled and arranged for the complete implementation of the process. The different modules are thus produced so that they can be positioned on truck trailers as shown in Figures 7a, 7b, 7c.

 At least two of the main modules (A, B) are established with a platform (Al, B1) arranged with anchoring and carrying zones to be moved by suitable handling and lifting means in order to be positioned or moved from the support trailer.

 The first module (A) is arranged to receive, support and maintain the components necessary for the selection of polluted products, selection made by grain size while the module B is arranged to receive a tank with soaking bath and distribution wheel.

 We will now describe the different components of the installation and related modules.

 The first module A is arranged from the platform A1 with a support structure referenced as a whole by SP intended to receive, maintain various components participating in the implementation of the method. This supporting structure is established from different vertical uprights (1) receiving walkways (2), scales (3) adapted to authorize the reception of said components and the intervention of personnel.

 The supporting structure is thus arranged, stepped, with for example two adjacent stages (E1) (E2) allowing the successive arrangement of said components in an established order and in an inclination configuration to ensure the different phases of implementation of the process.

 Thus, on the upper floor (El), and upstream of the installation, the supporting structure receives a frame (4) authorizing the positioning of a receiving hopper (5) of the masses M of polluted earth. This hopper is properly maintained on the support uprights of the frame, and it is capable of opening in its lower part on a water distribution conduit (6), duly supplied with the aid of a pump and similar means not shown. . Said hopper (5) is in the high position of the installation and it is capable of receiving the polluted products to be treated which come from a conveyor (7) with belts, or equivalent, conveying volumes of polluted products from the different batches aforementioned storage. Downstream of the conduit (6) and the hopper (5), there is provided a rotary conveyor (8) arranged internally with projecting means (8d) capable of creating or causing shocks and allowing the fragmentation in particles of the polluted products in course of treatment. This rotary conveyor (8) is arranged internally with a propeller facilitating the movement of the materials which are mixed with the water coming from the conduit (6). Said rotary conveyor (8) is suitably mounted on rollers and rolling means (9) allowing its rotation.

Said rollers are positioned on a fixed support frame (10) suitably positioned on the support structure of the module. It is thus carried out by means of this rotary conveyor a first grinding of the polluted material.

 According to a particular arrangement, the front end (8a) of the rotary conveyor (8) largely overflows from these rollers and support means (9), and has perforations (8b) at its end forming a first filter allowing evacuation downwards particles of material or pieces of material having a diameter less than a certain dimension, for example twenty millimeters. The particles of polluted products which do not meet this dimensional requirement, are then evacuated by the end (8c) of the conveyor by means of a chute (I 1) towards an evacuation conveyor (12) to end up in a bucket (13) for the removal of unselected particles or pieces at the outlet of the installation. The untreated polluted earth masses can then be sent again to the entrance of the installation for a new treatment cycle to obtain, thanks to the intervention of the rotary conveyor, additional fragmentation, or be treated differently.

 The particles or masses of polluted materials which meet the first criterion or dimensional particle size index are thus evacuated from the rotary conveyor (8) to fall by gravity into a washing screen (14) disposed below, the washing screen also being very long. to allow scrolling and processing of materials. This washing screen comprises an internal grid (15) established over the entire length of said screen and opening downstream thereof. This grid can in turn receive polluted materials for the second treatment phase. Projection nozzles (14a) of water or nozzle ramps again make it possible to fragment, thanks to the given spraying pressure of the fluid, the masses of materials found in the washer-screen.

The latter is positioned in inclination and is supported on fixed supports (16,17) arranged on the supporting structure.

 The internal grid (15) is also very long, opening by its end (1 Sa) out of the washing screen to a chute (18) for the outlet and evacuation of materials whose selected particle size index can be by example for example between 2 mm and 20 mm. Again, a discharge chute (18) for materials of such a particle size index is discharged to a bucket (19) at the outlet of the installation for recycling upstream of the installation or other procedures.

 The materials having thus been selected by the washing screen and having a particle size of less than 2 mm, pass through the grid and fall into the bottom of the washing screen to then be by gravity sprayed into a soaking tank (20) disposed on the module adjacent (B). A guide chute (21) facilitates the orientation of the collected materials of satisfactory particle size to orient them in the tank. This soaking tank is itself arranged to receive a paddle wheel (22) comprising on its periphery a plurality of scraper profile cups (23).

 Thus, the mass of polluted materials of small particle size, for example less than 2 mm, is sent and stored in the soaking tank, then scraped by the paddle wheel using the various buckets. These cups forming a receptacle have a particular profiled shape with in particular a zone (23a) forming a receptacle, an external face of sloping bottom (23b) whose function will appear subsequently. The scraper cups are themselves perforated (23c) in the form of grids and make it possible to scrape, grasp, move and drain the masses of polluted materials having a third particle size index of for example between 0.8 and 1.9 mm, all allowing the flow of the fluid. The finer particles are liable to form sludge and remain at the bottom of the soaking tank since they are liable to fall from the cups through the perforations (23c). This sludge is then evacuated using other means of the suction pump type allowing the evacuation of the treated water and very fine polluted charges.

 The masses of polluted materials with a particle size between 0.8 and 1.9mm, are then taken out of the soaking tank by the paddle wheel, to be conveyed through the buckets to the next postoperative phase.

 More particularly, there is a chute (24) for collecting the products collected by the paddle wheel, this chute being oriented inclined so as to receive, during the rotation of the paddle wheel, the materials collected with a view to conveying them to a vibrating table (25) which is itself held positioned on the module (A) of the installation.

 The treated materials are dried to be in the form of sand. Said vibrating table is itself arranged with a filtration grid (26) allowing the water to flow from below in the manner of a wringer, while the dried material particles are then removed using a conveyor (27) or several conveyors to a grab (28) for receiving the treated products.

Said products are then re-routed to the place of the initially polluted soil to be re-planted, but this time in a pollution control condition.

 In order to ensure all the appropriate maintenance of the installation, the various modules are arranged with passage areas and stairways ramps allowing access and control of the operation of the various components of the installation.

 According to the invention, such an installation makes it possible to treat approximately 80% of the masses of polluted materials thus leading to a satisfactory result having regard to the means used. The masses of untreated polluted materials such as sludge in particular are sent to a different operating station independent of this installation.

 The main means of the invention have thus been described. Some additional details should be provided.

 The installation is arranged upstream with a control unit (29) which makes it possible to define the characteristics and properties of the water or of the injected fluid as a function of the characteristics of the materials treated. At the outlet of the hopper (5) of the first sorting, this water or this fluid may have specificities depending on the nature of the pollution of the load to be treated, additive or other components which may indeed be associated with said fluid to allow treatment depollution.

 Furthermore, the pipes, distribution or water flow circuits which are of all known types, fall under the conventional implementation of a distribution, evacuation and recycling plant for waste water.

 According to the important provisions of the invention as indicated above, it is established in the form of modules which are capable of juxtaposing or coupling together so that they can then be transported on semi-trailer trucks as shown without limitation in FIGS. 6a , 6b, 6c. The module (A) positioned on the platform (Al) essentially comprises the structural elements supporting the hopper (5) and supporting the rotary conveyor (8), as well as support means of the washing screen (14), as as such, all the necessary arrangements allowing access to the various components.

 The module (B) intended to be transported on the trailer as shown in FIG. 6b, essentially comprises the soaking tank (20) or the settling tank associated with the paddle wheel (22) and its drive means.

 According to the invention, some of the components can be detached and positioned on a third platform (A3) using appropriate handling and lifting means. This is particularly the case of the rotary conveyor (8), of the washing screen (14) which are positioned using appropriate means on a trailer.

 The support modules (A, B) are arranged with a size and a base allowing a perfect adjustment on the platforms (A1-A2) by respecting the conditions and regulations of the Highway Code. This positioning of components on the platform (A3) meets this condition.

 It is thus understood that such an installation designed from modular elements adjustable between them, and the components being able to be transported independently, it is perfectly easy to be able to move the installation object of the invention in the best possible conditions.

 This does not aim to be able to treat the depollution at 100% of polluted materials, but it allows to ensure a treatment under conditions that can vary from 70 to 800 or more, while leaving a residue of sludge or materials polluted untreated and perfectly competitive treatment compared to existing facilities. The masses of materials in the particle size were greater than the requirements can be recycled for new treatments.

 I1 was also given by way of nonlimiting example of particle size values allowing the selection of sorting of the polluted materials treated, and without departing from the scope of the invention, given ranges can be adapted to the needs observed.

 The advantages stand out clearly from the invention and in particular the new concept which emphasizes putting the entire installation almost in situ on this site to be decontaminated, then moving it on trailers for other operations.

Claims (12)

 1 / Soil treatment and depollution process characterized by the implementation of the following operations  - The selected soil is precut into grid areas which are subject to chemical pollution measurements and analyzes;  - The masses of polluted soil are assembled in batches according to their degree and characteristics of pollution;  - We treat batch by batch successively by adapting the characteristics of the fluids participating in the depollution to the characteristics of the treated batches;  - Introduced into the treatment plant for polluted materials, successive masses of materials which are combined with one or more projections and distribution of fluids allowing the fragmentation of materials;  - Several washing and fragmentation operations are carried out, making it possible to select successive particle sizes of treated particles or pieces of polluted material, in order to ensure complete treatment of part of the initial mass of polluted materials with a specific particle size, the other pieces or parts of material being either disposed of for other recycling operations with a view to obtaining additional fragmentation, or being in the form of sludge for another treatment;  - Particles selected at a given particle size are then removed, dried to be reconditioned unpolluted on the treated site.  2 / Installation for implementing the soil depollution treatment according to the method of claim 1, characterized in that it comprises a support structure SP arranged to receive, maintain different components and materials necessary for the process, arranged in successive order for a continuous supply of polluted materials to be treated in combination with washing fluid distribution means, fragmentation means, filtration means, to select, distribute the pieces of material according to their particle size index, means for the masses of unselected materials, said polluted materials of a determined particle size being discharged in a soaking and decanting tank for a final selection with a view to separating very fine polluted materials in the form of sludge, materials from small particle size for drying and evacuation to be rested s in situ on the initially polluted site.  3 / Installation according to claim 2, characterized:  - In that it comprises means and components making it possible to carry out, in continuous feeding, at least two successive selections of polluted materials as a function of their particle size, masses of unselected materials being removed by means disposed at the outlet of the selection means , said means and components being arranged to authorize the distribution of fluid and of fragmentation of the materials:  - In that it comprises a settling tank and soaking of the selected materials, associated with a paddle wheel for the ultimate selection between materials in fine particles forming sludge intended to be treated independently, and a mass of material small particle size intended to undergo a drying operation to be removed and replaced in situ.  in that it comprises transportable modules (A, B, C) on trailer, each module receiving a part of the hardware components allowing the treatment of materials, at least two of said modules (A, B) being established with a platform form (Al, Bl) support for the components and materials, said platforms comprising means allowing their lifting and handling to position them either on the trailers for moving the installation, or to place them in situ near the site of depollution.  4 / Installation according to any one of claims 2 and 3, characterized:  5 / Installation according to any one of claims 2 to 4, characterized:  - In that the carrying structure (SP) is arranged to allow the successive positioning of the component materials in an inclination configuration and comprising a hopper (5) for receiving polluted masses, placed on a support frame, said masses being conveyed by conveying means (7), said hopper opening in its lower part into a water distribution conduit (6) in order to ensure mixing and fragmentation of said masses inside a rotary conveyor (8) arranged internally with complementary fragmentation means,  - In that said rotary conveyor being arranged with a filtration allowing a separation of the masses according to a first particle size index, the masses greater than this index being removed from the installation, the masses less than this index being conveyed to a washing screen (14),  - In that the washing screen (14) provides a second selection operation according to a second particle size index, the masses greater than this second index being discharged from the installation, the masses less than this second index being discharged into the tank soaking and settling.  6 / Installation according to claim 5, characterized:  - In that the rotary conveyor (8) is mounted on rolling means (9) positioned on a fixed support frame (10), the front end (8a) of said conveyor projecting from the support means (9) and having at its end, perforations (8b) forming filters allowing evacuation downwards into the washing screen (14);  - In that the washing screen is arranged internally with a filtration grid (15) and water distribution means (14a) for the fragmentation and washing of the masses of polluted materials in order to select according to the second particle size index masses of materials to be removed for recycling, and masses of materials to be treated in a third selection phase.  7 / Installation according to any one of claims 5 and 6, characterized in that at the outlet of the support structure receiving the components and materials for selecting the masses of materials, a settling and soaking tank (20) is arranged to receive a paddle wheel (22) having on its periphery a plurality of profiled buckets (23), scrapers, said buckets being arranged with perforations (23c) for scraping, grasping, moving, draining masses of polluted materials of a precise particle size to evacuate them to drying means in order to transport them in the depolluted state in the site of origin.  8 / Installation according to claim 7, characterized in that said buckets (23) have a zone (23a) forming a receptacle, an external face of sloping bottom (23b) for guiding the masses of polluted materials towards a sampling chute (24) routing them to a vibrating and drying table (25), the table having a filtration grid for the evacuation of water.  9 / Installation according to any one of claims 2 to 8, characterized in that  - The first granulometry index for the selection of the masses of materials defined by the rotary conveyor allows materials having a dimension greater than 20 mm to be removed.  - The second granulometry index for the selection of the masses of materials defined by the washing screen (14) enables materials having a dimension greater than 2 mm to be removed.  - The third granulometry index for the selection of the masses of materials defined by the perforation of the scraper cups makes it possible to keep only the masses of materials between 0.8 and 1.9 mm.  10 / Installation according to any one of claims 2 to 9, characterized in that it is controlled by a central control (19).  11 / Installation according to any one of claims 4 to 10, characterized:  - In that the module (A) positioned on the platform (Al) mainly comprises the supporting structure (SP), the support structure elements of the hopper, the rotary conveyor and the washing screen  - In that the module (B) positioned on the platform (B1) mainly comprises the soaking and settling tank, the paddle wheel.  12 / installation according to claim 11, characterized in that the transporter  rotary, the screen washer, the pipe duct are arranged on a trailer  independent.