FR2825361A1 - Procedure for extracting metal particles from fresh or crushed concrete involves using vibrating sieve and magnets at outlet - Google Patents

Abstract

Extraction of metal particles from fresh or crushed concrete involves breaking down the concrete and separating the different components, using one or more vibrating sieves (3) to direct different components towards their respective collection points (4, 5, 6). Metal particles are extracted from the sand by magnets (20) situated at the outlet or appropriate collection point (5). The extraction of metal particles and especially reinforcing fibers from fresh or crushed concrete is carried out by first breaking down the concrete and separating the different components, such as gravel, sand with metal particles, and cement dust, using one or more vibrating sieves (3) to direct the different components towards their respective collection points (4, 5, 6). The metal particles are extracted from the sand by magnets (20) situated at the outlet or the appropriate collection point (5). With fresh sand, the operation is carried out with the assistance of water jets (14, 15).

Description

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 Method and installation for extracting metallic particles from a concrete.

 The invention is in the field of civil engineering techniques, and its subject is a method and an installation for extracting metallic particles from concrete.

 Concretes are commonly loaded with metallic particles intended to increase their resistance, metallic fibers in particular. The presence of these metallic particles poses problems during the treatment of these concretes, when they are still fresh and recovered following the cleaning of the material used for their manufacture or their transport, or even when it is deconstruction concrete. Indeed, these particles are not extracted from the concrete during its reclassification, which is not desirable. In addition, these particles alter the equipment used for this, which often causes them to malfunction.

 The aim of the present invention is to propose a method and an installation for extracting from a concrete, fresh concrete or the like and deconstruction concrete in particular, metallic particles which it contains for its initial reinforcement.

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 The process of the invention generally consists in carrying out the following operations: a) parceling out the concrete, b) separating the various components of this parceled concrete, namely gravel, sand loaded with metallic particles, and cement dust, using at least one vibrating screen to isolate and route the components to respective collection stations. This operation aims to make the concrete inactive. c) extract the metallic particles from the loaded sand, using magnetic means arranged at the outlet of the corresponding collection station.

 Note that the method of the invention is applicable to concrete, whether fresh or deconstruction, and in general to any material combining gravel and sand loaded with metallic particles.

 It will be understood that in the case of deconstruction concrete, the step of parceling out the concrete is a specific step carried out, by grinding in particular, before the separation of its components. This operation is carried out dry, the vibration of the screen being sufficient to effect the separation of the components.

 In the case of treatment of fresh concrete, the operations of parceling and separation of this concrete into different

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 components are advantageously combined, and preferably use means for spraying water under pressure, associated with the vibrating screen.

 It will be noted that the spraying of water, in addition to its parceling function of the concrete, advantageously cooperates with the vibrating nature of the screen to participate in the separation of the concrete into its different components. In particular, this projection of water takes place in a dam to parcel out the finest components and cause them to pass through the mesh of the sieve, while the largest components are transported, thanks to the vibrations, to the corresponding collection station. .

 It will also be noted that the use of a vibrating screen has the advantage of providing a regular layer of collected charged sand, to facilitate the operation of extracting the metal particles by magnetic means.

 Finally, it should be noted that in the case of treatment of the concrete with sprayed water, the vibrations of the sieve are used to drain the components, and in particular the loaded sand, before their collection.

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 The present invention will be better understood and details will be apparent from the description which will be given of different embodiments of an installation for implementing the process described, in relation to the figures of the appended plates, in which: fig. 1 is a diagram illustrating a first exemplary embodiment of an installation for implementing the method of the invention, applied to fresh concrete, FIG. 2 is a top view of the installation illustrated in the previous figure, FIGS. 3, fig. 4 and fig. 5 are diagrams illustrating respective variants of a station for extracting metal particles from a loaded sand, located at the outlet of the corresponding collection station of an installation shown in the preceding figures.

 In fig. 1 and fig. 2, an installation for extracting metallic particles from a fresh concrete, for its initial reinforcement in particular, successively comprises: a) a station 1 for receiving the concrete, b) if necessary a parceling station, c ) a station 2 for separating the various components of the concrete, comprising a vibrating screen 3 and various collection stations, namely a

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 gravel collecting station 4, a loaded sand collecting station 5, and a cement collecting station 6, d) a station 7 for extracting metallic particles from the loaded sand, disposed at the outlet of the collecting station 5 the latter, e) stations 8 and 9 for collecting sand and metal particles respectively, arranged at the outlet of the extraction station 7.

 It will be noted that the separation station 2 also comprises ramps 10 for spraying water. This water is preferably filtered, to be reintroduced after treatment in the distribution circuit. For this, the installation further comprises means 11, 19 for collecting the projected water, and means for filtering the collected water, associated with means for recovering this water in the projection circuit. These latter different means, known in themselves, are not shown in the figures.

 Such an installation initially makes it possible to separate the gravel and the sand from the cement, in order to render the concrete inactive. Note in the example illustrated, that the screen 3 is a circular vibrating screen with three stages. However, the three separation functions of the concrete components can be carried out by means of respective respective sieves which are associated.

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 For example and analogously to the use of a stepped screen, a one-stage filter for gravel can be used, then a two-stage filter for the other components in cascade, in order to facilitate maintenance of the installation, as well as the various checks and adjustments, in particular vibrations.

 In addition, the vibrating screen 3 can have a rectangular conformation, without departing from the general rules set out.

 In the variant illustrated by way of example, the vibrating screen 3 is a rotary step screen with a circular base. This sieve comprises an upper stage 2 for the separation and collection of the gravel, a middle stage 12 for the separation and collection of the loaded sand, and a lower stage 13 for the collection of the cement.

 It will be noted that accessory ramps 14 are preferably provided during the collection of the loaded sand, to complete its washing.

 This vibrating screen 3 is for example equipped with an axial motor, or similarly with peripheral motors.

 In the example illustrated, the various collection stations 4,5, 6 and 11 are materialized by chutes. The vibrations of the sieve 3 are used to move the materials to their respective collection chute and to initiate the separation of the different components of the

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 concrete between them. The combined action of vibrations and water spray helps to separate the different components of concrete when it is still fresh.

 The gravel is first extracted on the canvas 15 from the top, with a mesh size of the order of between 3mm and 5mm. The loaded sand is retained on the central fabric 16, with a mesh size of the order of between 0.2 mm and 0.5 mm. It will be noted that these dimensions are given by way of indication, for metallic fibers of a common size of the order of 0.6mm for a length between 20mm and 100mm. The cement dust is retained by the lower fabric 17, while the water 18 is discharged. It will be noted that the evacuated water 18 can incidentally circulate through a fabric with a mesh size of the order of 0.05 mm, for its filtration before recovery.

 Referring furthermore to FIGS. 3 to fig. 5, the extraction station 7 comprises a conveyor 20 of the collected charged sand, to convey it through the magnetic means until separation and respective collection of the metallic particles and the sand.

 The magnetic means are in particular means for retaining metal particles to remove them from the sand, which is evacuated by gravity to the collection station 8 which is assigned to it, and to convey them to the corresponding collection station 9.

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 According to the various variants illustrated in FIGS. 1 to fig. 5, the magnetic means comprise any one of the following elements: a) the conveyor 20 itself which is magnetized (FIG. 1 and FIG. 2), so as to capture the magnetic fibers until separation from the sand. b) a movable surface 21 which overhangs the conveyor 20 (fig. 3). This surface 21 is in particular formed by a non-magnetic conveyor belt, which makes it possible to remove the metallic particles from the sand and to collect them on the fly, thanks to a permanent permanent magnet 30 located inside the carpet. c) a rotary drum 22 with a surface magnetized by a magnet 32 (fig. 5). The loaded sand flows along the surface of the drum 22, until the natural fall of the sand in the corresponding collection station 8, while the metallic particles are kept under the influence of the magnetism of the drum 22.

 It will be understood that, according to these various variants, the element participating in the magnetic means is equipped either with a scraper 23, or is magnetized over a restricted area so as to naturally release the metallic particles by gravity above their collecting station 9 The scraper 23 is notably arranged above the collecting station 9 for metallic particles, with a view to causing them to fall and to be recovered.

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 In the variant illustrated in FIG. 4, the magnetic means comprise a fixed magnetized surface 24 which overhangs the conveyor 20. It will be understood that this variant is more particularly suited to applications according to which the load of sand is poor.

 It will be noted that this mode of treatment of concrete after its use makes it possible to recycle each of its components, after their recovery at low cost.

Claims (10)

CLAIMS 1. - Process for extracting from a concrete, fresh concrete or the like and concrete of deconstruction in particular, of the metallic particles which it contains, characterized: in that it consists in carrying out the following operations: a) to partition the concrete , b) separate the various components of this parceled concrete, namely gravel, sand loaded with metallic particles, and cement dust, using at least one vibrating screen (3) to isolate and convey the components to respective collection stations ( 4,5, 6), c) extract the metallic particles from the loaded sand, using magnetic means (20,30, 32,24) arranged at the outlet of the corresponding collection station (5). <Desc / Clms Page number 11>  2. - Method according to claim 1, characterized: the concrete being a fresh concrete, the operations of parceling and separation of this concrete into different components are combined, and employ means (10, 14) of spraying water under pressure associated with the vibrating screen (3). 3.- Installation for the implementation of a process according to any one of claims 1 and 2, characterized: in that it successively comprises: - a station (1) for receiving the concrete, - if necessary a parceling station, a station (2) for separating the various components of the concrete, comprising the vibrating screen (3) and the various collecting stations (4,5, 6), namely a gravel collecting station (4) , a station (5) for collecting the loaded sand, and a station (6) for collecting the cement, - a station (7) for extracting metallic particles from the loaded sand, disposed at the outlet of the station (5) for collecting of the latter, - stations (8,9) for collecting sand and metallic particles respectively, arranged at the outlet of the extraction station (7). <Desc / Clms Page number 12>  4. - Installation according to claim 3, for the implementation of a method according to claim 2, characterized: in that the separation station (2) further comprises water spraying ramps (10), l installation comprising means (11, 19) for collecting the projected water (18).  5. - Installation according to claim 4, characterized: in that it comprises means for filtering the collected water (18), and for recovering this water (18) in the projection circuit.  6. - Installation according to any one of claims 3 to 5, characterized: in that the vibrating screen (3) is a stepped screen (2,12, 13) rotary circular base, comprising an upper stage (2) for separation and collection of gravel, a middle stage (12) for the separation and collection of loaded sand, and a lower stage (13) for the collection of cement.  7. - Installation according to claim 3, characterized: <Desc / Clms Page number 13>  in that the extraction station (7) comprises a conveyor (20) of the collected charged sand, for conveying it through the magnetic means (20,30, 32,24) until separation and respective collection of metallic particles and sand.  8. - Installation according to claim 7, characterized: in that the magnetic means (20.30, 32.24) are means for retaining metal particles to remove them from the sand, which is evacuated by gravity to the collection station (8) assigned to it, and to route them to the corresponding collection station (9).  9. - Installation according to claim 7, characterized: in that the magnetic means comprise any one of the following elements: - the conveyor (20) itself which is magnetized, - a permanent magnet (30) arranged in the inside of a non-magnetic mobile surface (21) which overhangs the conveyor, - a rotary drum (22) with a surface magnetized by a magnet (32), said element (20,30, 32) being equipped with a scraper (24 ) to improve the release of metallic particles from <Desc / Clms Page number 14>  the effect of magnetic attraction, this scraper (23) being disposed above the collecting station (8) of metallic particles. 10. - Installation according to claim 7, characterized: in that the magnetic means comprise a fixed magnetic surface (24) which overhangs the conveyor (20).