Method for mechanically separating different semiconducting, insulating or metallic materials from components or modules, such as photovoltaic modules, and recycling them - Patent Application 20070122997

Abstract

The present invention relates to a method for mechanically separating different materials from an end-of-life electronic module, the method comprising: a) providing a mixture of first elements (101) and second elements (103) in the form of strips, each strip having three dimensions in a Cartesian coordinate system, the first elements (101) having at least one dimension on the order of millimeters and the second elements (103) having at least one dimension less than 500 μm and less than 50 μm; b) placing the first and second elements in a trough (1); and c) applying mechanical vibration to the trough (1), which is inclined by an angle (α) between 10° and 30°, thereby spatially separating the first and second elements (101) towards the downstream end (14a) and the upstream end (13a), respectively.

Description

[Technical Field]

[0001] The present invention relates to the field of recycling components or modules made of different materials, in particular semiconducting, insulating and / or metallic materials, which need to be separated in order to efficiently recover them in whole or in part, which is particularly the case for photovoltaic cells and modules. In particular, the present invention relates to a method for mechanically separating the different elements contained in end-of-life photovoltaic modules. One objective is to recover silicon from photovoltaic cells by separating it from other elements such as glass, metals (e.g. copper, silver, etc.). [Background technology]

[0002] The deployment of photovoltaic modules has grown rapidly for decades, and more recently exponentially. Therefore, it is crucial to develop recycling processes for end-of-life or defective modules, as they are composed of valuable and reusable materials such as silicon and silver.

[0003] As illustrated in Figure 1, a typical photovoltaic module is composed of different materials: aluminum (frame), glass, plastic (polymer film and encapsulant), and silicon (photovoltaic cells), which together account for about 99% of the total weight. Small amounts of copper, silver, lead, tin, and zinc are also present for soldering and connectors.

[0004] Photovoltaic grade silicon has a very high purity, ranging from 6N (99.99999%) to 1N by weight. When recycling and reusing silicon cells from photovoltaic modules, it is important to keep this purity as high as possible. This high purity requirement necessitates particularly high sorting efficiency.

[0005] When a photovoltaic module is recycled, it is usually broken into pieces, for example by thermal treatment (pyrolysis) or mechanical treatment (in particular water jetting).

[0006] Processes exist to separate these pieces according to the type of material, which are based on optical separation, electrostatic separation, eddy current separation or mechanical separation.

[0007] At the scale of photovoltaic cells, this involves separating the silicon and silver wires that form the electrical contacts. Chemical and / or mechanical processes can be used to separate these silver wires from the silicon pieces. Reference can be made in particular to document FR 3096833, which proposes a recycling method that allows a physical separation between the silicon and silver wires of a photovoltaic cell.

[0008] When a mixture of silicon and silver flakes is obtained, it is not always easy to efficiently separate and separate the different types of material flakes.

[0009] In the field of recycling, and in particular in the field of photovoltaic cells, there may therefore be a strong desire to simplify the separation processes and make them more reliable in order to recycle as many of the materials that make up the cells as possible, since these materials may cross-contaminate if they are reinjected as a mixture into the recovery chain. Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention relates to a method for separating different materials (especially semiconductors and metals) forming a component or module, for efficient recycling and recovery of all or part of said materials. The method implements a trough with an inclination of 10° to 30° to the horizontal, in which elements made of different materials are placed and subjected to mechanical vibrations, resulting in spatial separation in the upstream (high side) or downstream (low side) regions of the trough, depending on the physical properties of the elements.

[0011] In particular, the invention relates to the recycling of photovoltaic cells and applies to the separation of silver and silicon with excellent efficiency. [Means for solving the problem]

[0012] The present invention relates to a method for mechanically separating different semiconducting, insulating or metallic materials from an end-of-life electronic component or module, the method comprising the following steps: a) providing a mixture of first and second elements in the form of pieces, each piece having three dimensions in a Cartesian coordinate system, the first elements having at least one dimension on the order of millimeters, and the second elements having at least one dimension less than 500 μm and less than 50 μm; b) disposing the first element and the second element in a central region of a trough, the trough being tray-shaped, solid in the central region, extending in a major plane, and having lateral flanges; and c) spatially separating the first and second elements by applying mechanical vibration to a trough, the trough being inclined such that a major plane forms an inclination angle of 10° to 30° with a substantially horizontal plane and so as to define upstream and downstream regions relative to a central region of the trough, and the second and first elements subjected to the mechanical vibration are transported towards the upstream and downstream regions of the trough, respectively.

[0013] According to advantageous features of the invention, taken alone or in any feasible combination, the following is performed: The tilt angle is 10° to 25°, preferably 20° to 25°, more preferably 20° to 25°, or even 21° to 25°, typically 23°. The electronic component or module is a stack containing photovoltaic cells, i.e. silicon layers, metal lines and layers. Step a) comprises disassembling the photovoltaic cell by mechanical or chemical treatment to separate the metal wires, the first material constituting the first element being silicon separated from the metal wires, and the second material constituting the second element being silver separated from the metal wires. The first element has a length and width of 1 mm to 20 mm and a thickness of about 150 μm. The second element has a length of less than 500 μm and a width and thickness of less than 50 μm. · Mechanical separation methods include a step d) of recovering the elements as they pass over the upstream or downstream end of the trough. The mechanical separation method comprises a step d) of recovering the elements in an upstream or downstream region of the trough, in which one or more openings are provided in the trays of the trough in the upstream and / or downstream region. The mechanical vibration in step c) is applied to the trough via a vibration system fixed to the trough, the mechanical vibration having a frequency of 40-60 Hz. The mechanical vibration applied to the trough is associated with a linear movement having an amplitude of 0.1 mm to 20 mm, preferably 0.1 mm to 1 mm. The linear movement is performed along an axis inclined at an angle of 10° to 30° to the main plane, said axis and the longitudinal axis of the trough being contained in a plane perpendicular to the main plane, preferably along an axis inclined at an angle of 20° to 25° to the main plane. The trough is formed from a material selected from steel, ceramic, quartz or silicon. [Brief explanation of the drawings]

[0014] Other features and advantages of the present invention will become apparent from the following detailed description of the invention, which proceeds with reference to the accompanying drawings. [Figure 1] 1 shows an exploded view of the components of a conventional photovoltaic panel. [Figure 2] 1A and 1B show diagrams illustrating a trough implemented in a mechanical separation method according to the present invention, where (a) is a top view and (b) is a side view. [Figure 3] 1 illustrates the trough and the separation between the first and second elements according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] The figures are schematic representations in which the relative dimensions between the various elements / components are not necessarily to scale.

[0016] The present invention relates to a method for mechanically separating different semiconducting, insulating or metallic materials from an end-of-life electronic component or module.

[0017] As will be explained below, the electronic component or module can be, for example, one or more photovoltaic cells 110 from a photovoltaic module 100. The materials considered are therefore in particular silicon and silver, which constitute different elements 101, 103 in the form of pieces or fragments, which constitute the objects to be separated and sorted.

[0018] Generally speaking, the method according to the invention is based on the spatial separation of the elements 101, 103 in a trough 1 that is suitably inclined and subjected to specific mechanical vibrations. a) providing two different types of elements 101, 103 to be sorted; - step b) placing said elements 101, 103 in the trough 1; - step c) of spatially separating the two types of elements 101, 103.

[0019] The trough 1 is in the form of a solid tray, at least in a central region 12, extending along a longitudinal axis A and having lateral flanges 11 (Fig. 2). The trough 1 is typically made of a material selected from steel, ceramic, quartz or silicon. The hardness of the material of the trough 1 must be close to or exceed the hardness of the material of the elements 101, 103 to be sorted, so that the elements do not damage it excessively. The tray is flat and smooth.

[0020] The lateral dimensions of the tray can vary from a few centimeters to several meters, depending on the amount of material to be processed. For example, the trough 1 can have a length along the longitudinal axis A of about 1 m and a width of the order of 50 cm. The height of the lateral flanges 11 is typically selected to be on the order of 1 cm to a few centimeters.

[0021] The distributor 5 may be positioned above the central region 12 of the trough 1 so as to gradually add the elements 101, 103 to the trays of the trough 1.

[0022] Spatial separation occurs when some elements 103 move towards the higher part (upstream region 13) of the trough 1 and other elements 101 move towards the lower part (downstream region 14). Such separation is made possible by the different geometries (flat, powder, etc.) of the elements 101, 103 present on the trough 1 in combination with the tilting and vibrating motion of the trough 1.

[0023] For the purposes of the present invention, the inclination angle α of the trough 1 is between 10° and 30°. An angle α of 10° means 10° ±0.5°. It should be noted that the inclination angle α corresponds to the angle formed between the horizontal plane and the main plane defined by the trays of the trough 1. One particular embodiment will now be described in detail, in which a more precise and advantageous range of the inclination angle α is proposed.

[0024] Mechanical vibration is advantageously applied to the trough 1 by a vibration system 2 fixed to the trough 1. The mechanical vibration typically has a frequency of 40 to 60 Hz, for example 50 Hz. It can be associated with a linear movement along an axis parallel or perpendicular to the main plane, or forming any angle with the main plane. The mechanical vibration can also be associated with an elliptical movement, which can be performed in the main plane, in a horizontal plane, or in any other plane. The amplitude of these various possible movements is preferably 0.1 mm to 20 mm, advantageously 0.1 mm to 1 mm, typically about 0.5 mm, or even about 0.3 mm. The vibration amplitude allows for controlling the jittering of the elements 101, 103, so that they undergo an acceleration suited to the requirements. If the amplitude is too low, both types of elements 101, 103 move downward. Conversely, if the amplitude is too high, all elements move upward or are thrown out of the trough 1.

[0025] In one preferred variant, the vibratory movement is linear along an axis that forms an angle of 10° to 30° (advantageously 20° to 25°) with the main plane (the plane of the trays of the trough 1), which main plane forms an inclination angle α of 10° to 30° with the horizontal plane, it being understood that the axis of the vibratory movement and the longitudinal axis A belong to the same plane that is perpendicular to the main plane.

[0026] The method includes a step d) of collecting the two types of elements 101, 103 as they pass over the upstream end 13a or the downstream end 14a, respectively, of the trough 1. For this purpose, containers 3, 4 can be placed below each of the ends 13a, 14a.

[0027] According to one possible variant, one or more openings (not shown) are made in the tray of the trough 1 in the upstream region 13 and / or the downstream region 14 to allow two distinct types of elements 101, 103, respectively, to pass through, and each type of element 101, 103 can then fall into dedicated containers 3, 4 placed below the one or more openings.

[0028] According to one particular embodiment of the present invention, a method for mechanically separating different semiconducting, insulating or metallic materials from an end-of-life electronic component or module comprises step a) of providing a mixture of first elements 101 and second elements 103 in the form of pieces, each piece having three dimensions (length L, width l, thickness e) in an orthogonal coordinate system (Figure 3).

[0029] Each first element 101 has at least one dimension of the order of millimeters, typically greater than or equal to 1 mm, or even greater than or equal to 2 mm. According to an advantageous variant, each first element 101 is generally flat in shape, so that its lateral dimensions (length L, width 1) are greater than its thickness e. The first elements 101 are thereby characterized by at least one dimension of the order of millimeters and by a shape factor (known as the first shape factor) that is advantageously greater than 6, or even greater than 10, 20, 50, or even more.

[0030] Each second element 103 has a dimension less than 500 μm and at least one dimension less than 50 μm. Typically, the second elements 103 are in the form of a powder, that is, in the form of very fine particles. In addition to their very small dimensions, these elements 103 may be substantially cylindrical in shape, the cross section of the cylinder then being defined by a width 1 and a thickness e, or, if it is circular, by a diameter φ.

[0031] Step b) involves placing a first element 101 and a second element 103 in a central region 12 of the trough 1. Note that the central region 12 of the trough 1 is not limited to the center of the tray, but can be considered to extend toward each of the upstream end 13a and downstream end 14a. Thus, elements 101, 103 can be added to trays closer or further from the upstream and downstream regions 13, 14, but still remain in the central region 12.

[0032] In step c), the first element 101 and the second element 103 are spatially separated by applying mechanical vibration (as described above) to the trough 1, which is inclined at an inclination angle α of 10° to 30° (±0.5°). The first element 101 is then transported to the downstream region 14 (lowest part) of the trough 1, while the second element 103 is transported to the upstream region 13 (highest part) (FIG. 3).

[0033] Advantageously, the inclination angle α of the trough 1 is between 15° and 25° (±0.5°), for example about 20°. Even more advantageously, the inclination angle α of the trough 1 is between 20° and 25° (±0.5°), or even between 21° and 25°, typically 23° (±0.5°). These preferred ranges of the inclination angle α significantly improve the separation efficiency of the first element 101 and the second element 103.

[0034] The spatial separation of the first elements 101 and the second elements 103 is facilitated by the fact that, in this tilt range of the trough 1, the balance of forces (friction, gravity, and the trough's reaction to the elements) is such that the first elements 101 (which are flat, for example) slide towards the lower part of the trough 1 (downstream region 14) as a result of reaching a breaking point of equilibrium due to friction. The dust-like second elements 103 are highly volatile and are subjected to air currents created by the vibratory movement of the trough 1. These air currents allow the second elements 103 to rise along the plate. When not being lifted by the air currents, the second elements 103 are held in place by the micro-irregularities of the trough 1.

[0035] In this embodiment, the electronic component or module is, for example, a photovoltaic cell 110, i.e., a stack including, inter alia, a silicon substrate, metal lines and layers. This cell 110 may originate from an end-of-life photovoltaic module (FIG. 1) that has been destroyed by thermal decomposition or mechanical techniques (such as water injection). The photovoltaic cell 110 may also originate from manufacturing scrap.

[0036] Step a) may then involve disassembling the photovoltaic cell 110 by mechanical (stripping) and / or chemical processing to separate the metal wires, and the first material constituting the first element 101 is then silicon (wholly or mostly) separated from the metal wires, and the second material constituting the second element 103 is silver separated from the metal wires.

[0037] The first element 101 may have a length L and width l of 1 mm to 20 mm, and a thickness e of the order of 150 μm. The second element 103 may have a length L of less than 500 μm, and a width l and thickness e (or diameter φ) of less than 50 μm. In particular, these are the range of dimensions of the first element 101 made of silicon and the second element 103 made of silver (metal wires) recovered from the photovoltaic cell 110.

[0038] The method according to the invention thereby allows for the mechanical separation of initially mixed silicon and silver pieces, which offers the advantage of a high separation efficiency when the first and second elements have sizes of the order of millimeters and micrometers, respectively, and have flat and powder shapes.

[0039] Of course, the invention is not limited to the described embodiments, and alternative embodiments may be added without departing from the scope of the invention as defined by the claims.

[0040] In particular, the mechanical separation method can be applied to the recycling of any kind of end-of-life electronic components and to elements made of materials other than silicon and silver, as long as the respective geometry of the elements, in combination with the tilt and vibration conditions of the trough, meets the prerequisites described herein.

Claims

1. 1. A mechanical separation method for mechanically separating silicon and silver pieces from end-of-life photovoltaic cells, said method comprising the steps of: a) providing a mixture of a first element (101) made of said silicon piece and a second element (103) made of said silver piece, each piece having three dimensions in a Cartesian coordinate system, said first element (101) having a length (L) and width (l) of 1 mm to 20 mm and a thickness (c) of the order of 150 μm, and said second element (103) having a length (L) of less than 500 μm and a width (l) and thickness (e) of less than 50 μm; b) placing said first element (101) and said second element (103) in a central region (12) of a trough (1), said trough (1) being tray-shaped, solid in said central region, extending in a main plane and having lateral flanges (11); c) spatially separating the first element (101) and the second element (103) by applying mechanical vibrations having a frequency of 40 to 60 Hz to the trough (1), wherein the trough (1) is inclined so that the main plane forms an inclination angle (α) of 20° to 25° with a substantially horizontal plane and so as to define an upstream region (13) and a downstream region (14) with respect to the central region (12) of the trough (1), and the second element (103) and the first element (101) subjected to the mechanical vibrations are transported towards the upstream region (13) and the downstream region (14) of the trough (1), respectively.

2. 2. The mechanical separation method according to claim 1, wherein the tilt angle is between 21° and 25°, preferably about 23°±0.5°.

3. 2. The mechanical separation method of claim 1, wherein step a) comprises disassembling the photovoltaic cell formed by a stack including a silicon layer, a metal wire and a layer by mechanical or chemical treatment to separate the metal wire, wherein the first material constituting the first element (101) is silicon separated from the metal wire and the second material constituting the second element (103) is silver separated from the metal wire.

4. - a step d) of recovering said elements (101, 103) as they pass over the upstream end (13a) or the downstream end (14a) of said trough (1), or A mechanical separation method according to any one of claims 1 to 3, comprising a step d) of recovering the elements (101, 103) in the upstream region (13) or in the downstream region (14) of the trough (1), wherein the trays of the trough (1) are provided with one or more openings in the upstream region (13) and / or in the downstream region (14).

5. 5. The mechanical separation method according to any one of claims 1 to 4, wherein the mechanical vibration in step c) is applied to the trough (1) via a vibration system (2) fixed to the trough (1).

6. A mechanical separation method according to any one of the preceding claims, wherein the mechanical vibration applied to the trough (1) is associated with a linear movement having an amplitude of between 0.1 mm and 1 mm.

7. 7. A mechanical separation method according to any one of claims 1 to 6, wherein the linear movement is performed along an axis inclined at an angle of 10° to 30° to the main plane, said axis and the longitudinal axis (A) of the trough (1) being contained in a plane perpendicular to the main plane.

8. A mechanical separation method according to any one of the preceding claims, wherein the trough (1) is made from a material selected from steel, ceramic, quartz or silicon.

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