FR2619025A1 - Device for grading a heterogeneous mixture of solid bodies - Google Patents

Abstract

Device for grading a heterogeneous mixture of solid bodies. The waste 18, coming from a grinder 10, travels on a conveyor 16 and then down a chute 20 where it undergoes a first moistening operation. It then drops into a vessel 22 containing a mass of water 28 which is constantly recycled. The light bodies collect at the upper part of the vessel 22 and are removed by an overflow effect. The heavy bodies collect at the bottom of the vessel and are removed along a pipe 50 which brings them to a series of successive screens 54, 56. Application to the grading of household waste.

Description

DEVICE FOR SORTING A HETEROGENEOUS BODY MIXTURE
SOLIDS
DESCRIPTION
The present invention relates to a device for sorting a heterogeneous mixture of solid bodies applicable in particular but not exclusively for separating the organic materials contained in household waste in order to subject them to a subsequent methanization treatment.

 There are currently sorting methods for removing organic matter containing garbage or other mixtures of solids. In general, the separation is done by density difference, the mixture being introduced into a tank filled with water so that the light bodies (that is to say of density less than 1) gather on the surface and that the heavy bodies (generally inert materials such as metals, glasses, ceramics, etc.) collect at the bottom of the tank.

 The subject of the present invention is precisely a device used for sorting according to this density method continuously and automatically with a higher efficiency than that of the devices of the prior art.

The device object of the invention comprises, in known manner - a tank arranged vertically and able to contain a mass
water, - means for introducing water into this tank so
continues so that it constantly overflows as a result of
overflow, - means for introducing the mixture into the tank, the bodies
heavy gathering at the bottom of the tank and
Light bodies gathering at the top of The tank
and being entrained by the water leaving by the overflow effect, - means for separating the light bodies from their water
training, - means of evacuation of light bodies after this
separation, - means for recycling said entrainment water in the
tank, and - means for evacuating heavy bodies.

According to the invention, the means for removing heavy bodies comprise - a pipe whose cross section is greater than the dimension
maximum of said heavy bodies, this pipe having a
first end communicating with the lower part of La
tank where heavy bodies gather and a
second end located at a higher level than the
first, - a heavy body treatment installation, said
pipe being arranged so that the material exiting through
its second end enter this installation, and - means for circulating along said pipe,
its first end towards its second end, the water
located at the bottom of the tank and in which
collect the heavy bodies.

In the preferred embodiment, said installation for treating heavy bodies comprises - a series of sieves arranged one above the other and
whose mesh width decreases from top to bottom, the
second end of said pipe being arranged so
to pour the materials circulating in this pipe on the
first sieve, - means for vibrating all the sieves, - means for separate removal of the materials retained by
each of the sieves, and - means for recycling into the tank the water having passed through all
the sieves.

 According to another aspect of the invention, the device further comprises means for wetting the solid bodies before their introduction into the tank.

According to another characteristic of the invention, the device further comprises: - a sleeve open at its two ends and arranged substantially
vertically inside your tank, and - a gas inlet arranged so as to send bubbles of
gas from bottom to top inside the sleeve.

 Finally, according to another aspect of the invention, the device further comprises a water inlet pipe opening tangentially into the tank inside the body of water. This line is used to impart to the liquid contained in the tank a rotational movement which facilitates the evacuation of the light part.

 The invention will appear better on reading the description which follows, given by way of purely illustrative and in no way limiting, with reference to the appended drawing, which comprises a single figure which is a schematic view in vertical section of the device which is the subject of the invention.

 If we refer to the drawing, we see that the mixture to be sorted first passes through a crusher 10 where the waste is shredded in order to obtain pieces having maximum dimensions of the order of a few centimeters. The waste 18, then driven by an endless screw 12 actuated by a motor 14, is ejected on a conveyor 16. The waste 18 then falls into an inclined chute 20 so that the waste descends by gravity into a tank 22 in which is sorted. Preferably, this tank 22 has a symmetry of revolution.

 It has been found that separation efficiency is improved if the waste is wetted before it enters the body of water contained in the tank. This is why one or more orifices 24 have been provided making it possible to send a certain amount of water to the waste located in the chute 20. These different orifices 24 are connected by a pipe 26 to a water inlet (not shown).

 The waste leaving the chute 20 falls into the tank 22, which contains a mass of water 28 in order to separate, by difference in density, the heavy bodies which will fall to the bottom of the tank and the light bodies (i.e. - essentially say organic matter) which will collect at the top of the tank. The waste coming from the chute 20 falls into a vertical tube 30, the lower part of which is slightly below the surface of the liquid contained in the tank. This arrangement makes it possible to better channel the solid materials and to improve their pre-wetting in order to prevent some of them from floating on the surface.

 We also see, below the tube 30 and inside the body of water 28, a sleeve 32 open at its two ends and arranged vertically in the tank 22. A gas inlet 34 located at the bottom of the tank makes it possible to send gas bubbles into the body of water, these bubbles traveling from bottom to top inside the sleeve 32. This makes it possible to stir the liquid located inside the tank. This stirring by a dispersion of gas has three uses.

 First of all, this keeps the bodies to be sorted in suspension thanks to the macroscopic turbulence thus created. On the other hand, this causes a certain washing of the waste thanks to microscopic turbulence. Finally, in the case where waste is treated to extract materials intended to be fermented, the latter thus undergo a first aerobic fermentation which can favor the subsequent methanization treatment.

 In addition, this turbulence means that the different bodies to be sorted are subjected to rotational movements in all directions and the geometry or the shape of the waste no longer matters. Indeed, it could be that certain wastes, because of their shape, fall quickly or rise quickly to the surface and that we find a significant proportion of organic matter in inert wastes and vice versa. The turbulence created in the liquid means that the position of the different solid bodies is arbitrary and that they go up or down in the liquid mass only according to their density.

 A pump 36 makes it possible to constantly send water to the lower part of the tank so that the latter constantly overflows due to the overflow effect. The mounting of the pump 36 will be described in more detail below in the rest of the present description.

 Since the light bodies collect on the surface of the body of water 28 contained in the tank 22, they are discharged continuously by the effect of overflow through the notch 38 provided at the upper part of the tank . The mixture of water and light bodies falls into a chute 40, then, via a pipe 42, onto a conveyor 44. Preferably, the latter is arranged so as to entrain the waste from bottom to top and it consists of a fine mesh canvas allowing water to pass through while retaining the waste. Thus, the latter can be evacuated while the water falls back into a first recovery tank 46 in two different ways: in fact, part of the water can slide along the conveyor 44 and another part falls directly through the mesh of the fabric constituting this conveyor. The water collected at the bottom of the tank is returned to the pump 36 via a pipe 48 shown diagrammatically in phantom in the drawing.

 As for light bodies, they can be treated and recovered by a subsequent treatment, for example transformed into compost by methanization.

As for the heavy bodies, they gradually fall to the bottom of the tank and, from there, arrive in a pipe - 50, which is in communication with the pump 36. Under the action of
The pump 36, the water arriving from the tank 22 in the pipe 50 is evacuated from bottom to top Along this pipe in the direction of arrow F. The mixture of water and heavy bodies thus circulates from below at the top along the pipe 50 to the outlet orifice 52 of the latter, which is at a higher level than the first end of the pipe 50, that is to say at a higher level that the lower part of the tank 22. The orifice 52 of the pipe 50 is arranged so as to project the mixture which leaves it onto a first sieve 54 with large meshes (for example 3 mm meshes) which serves to retain large heavy waste. Water and small waste having passed through the screen 54 then arrive on a second screen 56 with fine mesh (for example of the order of 1 mm) located below the first . This second screen retains the small heavy bodies while letting the water which falls back into a second recovery tank 58 thanks to a pipe 60. A vibration device 62 mounted on the tank 58 allows to simultaneously vibrate the assembly of the two sieves 54 and 56. This setting in vibration allows the screening of the waste and their evacuation by conduits 64 and 66. The conduit 64 is used for the evacuation of the solid bodies retained by the sieve 54 and the conduit 66 is used for the evacuation of the waste retained by the sieve 56. The waste thus recovered can be evacuated or sent to another treatment installation, for example to undergo further sorting. As for the water falling back into the recovery tank 58, it returns to the pump 36 via a pipe 68.

 We will now describe in more detail the mounting of the pump 36 and its connection to the rest of the installation.

 We see that it is supplied by a supply line 70 which can be connected to an external water supply (not shown) and which communicates with the lines 48 and 68 already mentioned. Thus, the pump can suck the water from the two recovery tanks 46 and 58 and, optionally, also from the external supply. The water discharged by the pump 36 can follow several paths. First of all, it goes into the pipe 50, already described, which has a valve 72 located between the pump 36 and the point where the pipe 50 communicates with the lower part of the tank 22.

A pipe 74 fitted with a valve 76 communicates on the one hand with the pipe 50 at a point thereof situated between the pump 36 and the valve 72 and on the other hand with the lower part of the tank.

Finally, a last pipe 78 fitted with a valve 80 connects the pipe 50, at a point located between your pump 36 and the valve 72, to your recovery tank 36.

 In normal operation, the valve 72 is open while the valve 80 is closed. As for the valve 76, it can be opened or closed depending on the operating mode chosen.

Thus, the pump sucks up the water coming from the recovery tanks 46 and 58 through the lines 48 and 68 and rejects this water on the one hand through the line 50 to ensure the evacuation of the heavy materials and, on the other hand, in the tank 22 in order to continuously recycle the water contained therein. As for the valve 80, it is only open in certain exceptional cases to return the water from the pump directly to the tank 46, for example when one wishes to intervene for the maintenance of another part of the installation. .

 Finally, the pump can be used to send water (via a set of pipes not shown in the drawing) to the pipes 26, to convey the water used for wetting the waste brought into the chute 20.

Those skilled in the art will choose the flow rates in the various pipes according to each particular case, and in particular the nature, dimensions, quantities, etc. waste to be sorted.

 We can also see in the drawing a pipe 82 fitted with a valve 84, which opens into the tank 22 inside the body of water 28. The pipe 82 opens tangentially inside the tank 22 in order to impart a rotational movement to the liquid 28 contained therein, which facilitates the evacuation of Light bodies. It can be connected to pump 36 or to another water supply.

 Thus, the device that is the subject of the invention has interesting advantages since it is simple and therefore inexpensive to produce and that it allows efficient sorting of waste automatically and continuously.

 Finally, it is understood that the invention is not limited to the single embodiment which has just been described, but that variants can be envisaged without thereby departing from the scope of the invention. This is how we can vary the shape and dimensions of the different parts of the device depending on the waste to be sorted and use any number of sieves to sort the heavy bodies.

Claims (5)

 1. Device for sorting a heterogeneous mixture of solid bodies (18) comprising light bodies and heavy bodies, this device comprising: - a tank (22) arranged vertically and capable of containing a  body of water (28), - means for introducing water into this tank (22) so  continues so that it constantly overflows as a result of  overflow, - means for introducing the mixture (18) into the tank (22),  heavy bodies gathering at the bottom of the  tank (22) and the light bodies collecting at the part  upper part of the tank and being entrained by the water leaving  overflow effect, - means for separating light bodies from their water  training, - means of evacuation of light bodies after this  separation, - means for recycling said entrainment water in the  tank (22), and - means for evacuating heavy bodies, characterized in that the means for evacuating heavy bodies comprise - a pipe (50) the cross section of which is greater than the dimension  maximum of said heavy bodies, this pipe (50) having a  first end communicating with the lower part of La  tank (22) at the place where the heavy bodies and a  second end located at a higher level than the  first, - a heavy body treatment installation, said  line (50) being arranged so that the materials leaving  by its second end enter this installation, and - means (36) for circulating along said pipe  (50), from its first end to its second end,  the water at the bottom of the tank (22) and  in which heavy bodies gather.  2. Device according to claim 1, characterized in that said treatment installation comprises: - a series of sieves (54, 56) arranged one above the  others and whose mesh width decreases from top to bottom  bottom, The second end of said pipe (50) being  arranged to discharge the material flowing into  this pipe (50) on the first screen (54), - means for vibrating all the screens (54,  56), - means of separate removal of the materials retained by  each of the sieves, and - means for recycling into the tank (22) the water having passed through  all sieves (54, 56).  3. Device according to claim 1, characterized in that it further comprises means (26, 24) for wetting said solid bodies before their introduction into the tank (22).  4. Device according to claim 1, characterized in that it further comprises - a sleeve (32) open at its two ends and arranged  substantially vertically inside the tank (22), and - a gas inlet (34) arranged so as to send  gas bubbles from bottom to top inside the sleeve (32).  5. Device according to claim 1, characterized in that it further comprises a pipe (82) of water inlet tangentially opening into the tank (22) inside the body of water (28).