Method for mechanically separating different semiconductor, insulating or metal materials from a component or module, for example a photovoltaic module, in order to recycle same

Abstract

The invention relates to a method for mechanically separating different materials from an electronic module at end of life, the method comprising: a) providing a mixture of first (101) and second (103) elements, in the form of pieces, each piece having three dimensions in an orthonormal frame of reference, the first elements (101) having at least one dimension of the order of millimeters and the second elements (103) having dimensions smaller than 500 μm and at least one dimension smaller than 50 μm; b) arranging the first and second elements in a trough (1); c) spatially separating the first (101) and second (102) elements toward a downstream end (14a) and an upstream end (13a), respectively, by applying a mechanical vibration to the trough (1), which is inclined by an angle (α) of between 10° and 30°.

Description

PROCESS FOR THE MECHANICAL SEPARATION OF DIFFERENT SEMICONDUCTOR, INSULATING OR METALLIC MATERIALS FROM A COMPONENT OR MODULE, FOR EXAMPLE PHOTOVOLTAIC, FOR THE RECYCLING OF THE LATTER FIELD OF THE INVENTION

[0001] The present invention relates to the field of recycling components or modules formed from different materials, in particular semiconductors, insulators and / or metals, materials which need to be separated in order to effectively recover them in whole or in part; this is particularly the case for photovoltaic modules and cells. In particular, the invention therefore relates to a method for mechanically separating different elements included in a photovoltaic module at the end of its life, one objective being to recover the silicon from the photovoltaic cells, separated from other elements such as glass, metals (for example, copper, silver, etc.), etc. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] The deployment of photovoltaic modules has been growing rapidly over the past few decades, and has more recently increased exponentially. It is therefore essential to develop recycling processes for end-of-life or defective modules, as they are made of valuable and recyclable materials, including silicon, silver, etc.

[0003] As illustrated in the figure, a typical photovoltaic module is made up of different materials: aluminum (frame), glass, plastic (encapsulant and polymer membrane), 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 used for soldering and connections.

[0004] Photovoltaic-grade silicon has a very high purity ranging from 6N (99.99999%) to 11N by weight. It is important, when recycling and reusing silicon cells from a photovoltaic module, to maintain this purity as much as possible. This high purity recommendation therefore requires particularly high sorting efficiency.

[0005] When a photovoltaic module needs to be recycled, it is usually broken down into pieces, for example by using thermal treatments (pyrolysis) or mechanical treatments (water jet in particular).

[0006] There are processes for separating these pieces according to the nature of their material; they are based on optical separation, electrostatic separation, eddy current separation or even mechanical separation.

[0007] At the photovoltaic cell level, it is particularly necessary to separate the silicon and the silver lines that form the electrical contacts. There are chemical and / or mechanical treatments that can detach these silver lines from the pieces of silicon. Reference can be made to document FR3096833, which proposes a recycling process that allows the physical division between the silicon and the silver lines of a photovoltaic cell.

[0008] Obtaining a mixture of silicon pieces and silver pieces, it is not always easy to sort and segregate pieces of different materials effectively.

[0009] In the field of recycling, particularly of photovoltaic cells, there is therefore a strong advantage in simplifying and making more reliable separation processes in order to recycle as much as possible of the materials forming the cells, as these materials can be polluting for each other if they are reinjected mixed into a recovery chain. SUBJECT OF THE INVENTION

[0010] The present invention relates to a method for separating different materials (in particular semiconductors and metals) forming components or modules, so as to efficiently recycle and recover all or part of said materials. The method uses a trough having an inclination between 10° and 30° relative to the horizontal: elements composed of the different materials are arranged in the trough and, subjected to mechanical vibration, undergo a spatial separation in an upstream zone (on the high side) or downstream zone (on the low side) of the trough, depending on the physical characteristics of said elements.

[0011] The invention relates in particular to the recycling of photovoltaic cells and is applied with excellent efficiency to the separation of silver and silicon. BRIEF DESCRIPTION OF THE INVENTION

[0012] The present invention relates to a method for mechanically separating different semiconductor, insulating or metallic materials from an end-of-life electronic component or module, comprising the following steps:

[0013] a) providing a mixture of first elements and second elements, in the form of pieces, each piece having three dimensions in an orthonormal frame of reference, the first elements having at least one dimension of millimetric order and the second elements having dimensions less than 500μm and at least one dimension less than 50μm,b) arranging the first elements and the second elements in a central zone of a trough, said trough having a tray shape, solid in the central zone, extending in a main plane, and comprising lateral edges;c) the spatial separation of the first elements and the second elements, by applying a mechanical vibration to the trough, said trough being inclined so that the main plane forms an angle of inclination of between 10° and 30° with a substantially horizontal plane and so as to define an upstream zone and a downstream zone relative to the central zone of the trough, the second elements and the first elements, subjected to the mechanical vibration, being conveyed respectively towards the upstream zone and towards the downstream zone of the trough.;

[0014] According to advantageous characteristics of the invention, taken alone or in any feasible combination: the angle of inclination is between 10° and 25°, preferably between 20° and 25°, still preferably between 20° and 25°, or even between 21° and 25°, typically 23°; the electronic component or module is a photovoltaic cell, namely a stack comprising a silicon layer, layers and metal lines; step a) comprises the division of the photovoltaic cell by mechanical or chemical treatment, so as to detach the metal lines, the first material composing the first elements being silicon, the second material composing the second elements being the silver of the metal lines; the first elements have a length and a width of between 1mm and 20mm and a thickness of the order of 150μm;the second elements have a length of less than 500μm, and a width and a thickness of less than 50μm;the mechanical separation method comprises a step d) of recovering the elements, when they pass beyond an upstream end or a downstream end of the trough;the mechanical separation method comprises a step d) of recovering the elements in the upstream zone or in the downstream zone of the trough, one or more orifices being provided in the tray of the trough in said upstream zone and / or said downstream zone;the mechanical vibration in step c) is applied to the trough by means of a vibrating system, integral with the trough, the mechanical vibration having a frequency of between 40 and 60 Hz;the mechanical vibration applied to the trough is associated with a rectilinear movement of amplitude of between 0.1 mm and 20 mm, preferably between 0.1 mm and 1 mm;the rectilinear movement takes place along an axis inclined by 10° to 30° relative to the main plane, said axis and the longitudinal axis of the trough being included in a plane normal to the main plane; preferably, the rectilinear movement takes place along an axis inclined by 20° to 25° relative to the main plane; the trough is formed from a material chosen from steel, ceramic, quartz or silicon.;

[0015] Other characteristics and advantages of the invention will emerge from the detailed description which follows with reference to the appended figures:

[0016] This is an exploded view of the components of a classic photovoltaic panel;

[0017] The present invention shows a trough implemented in the mechanical separation method according to the present invention, (a) in top view and (b) in side view;

[0018] The present invention provides a trough and a separation between first and second members.

[0019] The figures are schematic representations in which the relative dimensions between the different elements / components are not necessarily respected. DETAILED DESCRIPTION OF THE INVENTION

[0020] The invention relates to a method for mechanically separating different semiconductor, insulating or metallic materials from an end-of-life electronic component or module.

[0021] As will be specified later, the electronic component or module may for example be one (or more) photovoltaic cell(s) 110, for example from a photovoltaic module 100. The materials considered are therefore in particular silicon and silver; they compose different elements 101, 103, in the form of pieces or fragments, which constitute objects to be separated and sorted.

[0022] In general, the method according to the invention is based on the spatial separation of said elements 101, 103, in a trough 1 inclined in a suitable manner and subjected to a particular mechanical vibration. It typically comprises:A step a) of providing two different types of elements 101, 103 to be sorted,A step b) of arranging said elements 101, 103 in the trough 1,A step c) of spatial separation of the two types of elements 101, 103.

[0023] The trough 1 has the shape of a solid tray, at least in a central zone 12, extending along a longitudinal axis A, and comprising lateral edges 11 (). The trough 1 is typically formed from a material chosen 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 materials of the elements 101, 103 to be sorted, so that the latter do not damage it excessively. The tray is flat and smooth.

[0024] The lateral dimensions of the tray can vary from a few centimeters to several meters, depending on the quantity of material to be processed. For example, the trough 1 can have a length, along the longitudinal axis A, of approximately 1 m and a width of the order of 50 cm. The height of the lateral edges 11 is typically chosen to be of the order of 1 cm to a few cm.

[0025] A distribution device 5 can be arranged above the central zone 12 of the trough 1, so as to gradually introduce the elements 101, 103 onto the tray of the trough 1.

[0026] The spatial separation occurs due to the movement of certain elements 103 towards the higher part (called upstream zone 13) of the trough 1 while other elements 101 move towards the lower part (called downstream zone 14). Such a separation is made possible due to the different geometry (planar shape, powdery shape, etc.) of the elements 101, 103 present on the trough 1, in combination with the inclination and the vibratory movement of the trough 1.

[0027] In the context of the present invention, the angle of inclination α of the trough 1 is between 10° and 30°. When we speak of an angle α of 10°, we must understand 10° + / -0.5°. Note that the angle of inclination α corresponds to the angle formed between a horizontal plane and a main plane defined by the plate of the trough 1. A particular embodiment will then be detailed, in which more precise and more advantageous ranges of angles of inclination α are proposed.

[0028] The mechanical vibration is advantageously applied to the trough 1 by means of a vibrating system 2, integral with the trough 1. The mechanical vibration typically has a frequency of between 40 and 60 Hz, for example 50 Hz. It can be associated with a rectilinear movement along an axis parallel or normal to the main plane, or forming any angle with said main plane. The mechanical vibration can also be associated with an elliptical movement, which can take place in the main plane, in the horizontal plane or in any other plane. The amplitude of these different possible movements is preferably between 0.1 mm and 20 mm, advantageously between 0.1 mm and 1 mm, typically around 0.5 mm, or even around 0.3 mm. The amplitude of the vibrations makes it possible to regulate the jittering of the elements 101, 103, so that they are subjected to an acceleration adapted to the need.With too low an amplitude, the two types of elements 101,103 would move downwards; on the contrary, too high an amplitude would cause all the elements to move upwards or be ejected from the trough 1.

[0029] According to a preferred variant, the vibratory movement is rectilinear, along an axis forming an angle of between 10° and 30° (advantageously between 20° and 25°) with the main plane (plane of the tray of the trough 1), it being understood that the main plane forms an angle of inclination α of between 10° and 30° with the horizontal plane and that the axis of the vibratory movement and the longitudinal axis A belong to the same plane normal to the main plane.

[0030] The method comprises a step d) of recovering the two types of elements 101, 103, when they pass respectively beyond an upstream end 13a or a downstream end 14a of the trough 1. For this, containers 3, 4 can be arranged below each of the ends 13a, 14a.

[0031] According to a possible variant, one or more orifices (not shown) are arranged in the tray of the trough 1 in the upstream zone 13 and / or in the downstream zone 14, to allow one and the other of the two types of separate elements 101, 103 to pass respectively; each type of element 101, 103 can then fall into a dedicated container 3, 4, arranged under the orifice(s).

[0032] According to a particular embodiment of the invention, the method for mechanically separating different semiconductor, insulating or metallic materials from an electronic component or module at the end of its life, comprises a 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 orthonormal reference frame ().

[0033] Each first element 101 has at least one millimetric dimension, typically greater than or equal to 1 mm, or even 2 mm. According to an advantageous variant, each first element 101 has a generally planar shape: its lateral dimensions (length L, width l) are therefore greater than its thickness e. The first elements 101 are thus characterized by at least one millimetric dimension and advantageously, a form factor (called first form factor) greater than 6, or even greater than 10, 20, 50, or even more.

[0034] Each second element 103 has dimensions less than 500 μm and at least one dimension less than 50 μm. Typically, the second elements 103 are in powder form, in other words, in the form of very fine particles. These elements 103, in addition to their very small dimensions, may be in a substantially cylindrical shape, the section of the cylinder may then be defined by a width l and a thickness e, or by a diameter ϕ if it is circular.

[0035] Step b) comprises the arrangement of the first elements 101 and the second elements 103 in a central zone 12 of the trough 1. It should be remembered that the central zone 12 of the trough 1 is not limited to the center of the tray, but is considered to extend towards each of the upstream 13a and downstream 14a ends. The introduction of the elements 101, 103 onto the tray can therefore take place more or less close to / far from said upstream 13 and downstream 14 zones, while remaining in the central zone 12.

[0036] In step c), the spatial separation of the first elements 101 and the second elements 103 occurs, by applying a mechanical vibration (as previously described) to the trough 1, which is inclined with an angle of inclination α of between 10° and 30° (+ / -0.5°). The first elements 101 are then conveyed to the downstream zone 14 (lowest part) of the trough 1, while the second elements 103 are conveyed to the upstream zone 13 (highest part) ().

[0037] Advantageously, the angle of inclination α of the trough 1 is between 15° and 25° (+ / -0.5°), for example around 20°. Also advantageously, the angle of inclination α of the trough 1 is between 20° and 25° (+ / -0.5°), or even between 21° and 25°, or typically 23° (+ / -0.5°). These preferential ranges of angle of inclination α significantly improve the separation efficiency of the first 101 and second 103 elements.

[0038] The spatial separation of the first 101 and second 103 elements is favored by the fact that, in this range of inclination of the trough 1, the balance of forces (friction, gravity, reaction of the trough on the elements) is such that it causes the first elements 101 (for example planes) to slide towards the lower part of the trough 1 (downstream zone 14), due to the reaching of a breaking point of the equilibrium due to friction. The second elements 103, similar to dust, are very highly volatile and subject to the air currents created by the vibratory movements of the trough 1; these air currents allow the second elements 103 to rise along the plate. When they are not lifted by the air currents, the second elements 103 are retained by the micro-asperities of the trough 1.

[0039] In this embodiment, the electronic component or module is for example a photovoltaic cell 110, namely a stack comprising in particular a silicon substrate, layers and metal lines. This cell 110 may come from a photovoltaic module 100 () at the end of its life, dislocated by pyrolysis or by mechanical techniques (water jet, etc.). The photovoltaic cell 110 may also come from production waste.

[0040] Step a) can then comprise the division of the photovoltaic cell 110 by mechanical (exfoliation) and / or chemical treatment, so as to detach the metal lines: the first material composing the first elements 101 is then silicon (totally or predominantly), the second material composing the second elements 103 is the silver of the metal lines.

[0041] The first elements 101 may have a length L and a width l of between 1 mm and 20 mm and a thickness e of the order of 150 μm. The second elements 103 may have a length L of less than 500 μm and a width l and a thickness e (or a diameter ϕ) of less than 50 μm. These are in particular the ranges of dimensions of the first elements 101 made of silicon and of the second elements 103 made of silver (metal wires) recovered from a photovoltaic cell 110.

[0042] The method according to the invention thus allows mechanical separation between pieces of silicon and pieces of silver, initially mixed. It has the advantage of high segregation efficiency in this specific case of first and second elements having respectively millimetric and micrometric sizes and respectively flat and powdery shapes.

[0043] The invention is not limited to the embodiment described and variant embodiments may be made without departing from the scope of the invention as defined by the claims.

[0044] In particular, the mechanical separation process can be applied to the recycling of any kind of end-of-life electronic component, and to elements composed of materials other than silicon and silver, as long as the respective shapes of the elements, in combination with the tilting and vibration conditions of the trough, meet the prerequisites set out in this description.

Claims

Method for mechanically separating pieces of silicon and pieces of silver from a photovoltaic cell at the end of its life, comprising the following steps: a) providing a mixture of first elements (101) consisting of the pieces of silicon, and second elements (103) consisting of the pieces of silver, each piece having three dimensions in an orthonormal reference frame, the first elements (101) having a length (L) and a width (l) of between 1 mm and 20 mm and a thickness (e) of the order of 150 μm and the second elements (103) having a length (L) of less than 500 μm, and a width (l) and a thickness (e) of less than 50 μm, b) arranging the first elements (101) and the second elements (103) in a central zone (12) of a trough (1), said trough (1) having a tray shape, solid in the central zone, extending in a main plane, and comprising lateral edges (11);c) the spatial separation of the first elements (101) and the second elements (103), by applying a mechanical vibration to the trough (1), the mechanical vibration having a frequency of between 40 and 60 Hz, said trough (1) being inclined so that the main plane forms an angle of inclination (α) of between 20° and 25° with a substantially horizontal plane and so as to define an upstream zone (13) and a downstream zone (14) relative to the central zone (12) of the trough (1), the second elements (103) and the first elements (101), subjected to the mechanical vibration, being conveyed respectively towards the upstream zone (13) and towards the downstream zone (14) of the trough (1).; Mechanical separation method according to the preceding claim, in which the angle of inclination is between 21° and 25°, preferably around 23° + / -0.5°. Mechanical separation method according to claim 1, wherein step a) comprises dividing the photovoltaic cell, formed by a stack comprising a silicon layer, layers and metal lines, by mechanical or chemical treatment, so as to detach the metal lines, the first material composing the first elements (101) being silicon, the second material composing the second elements (103) being the silver of the metal lines. Mechanical separation method according to one of the preceding claims, comprising:- a step d) of recovering the elements (101, 103), when they pass beyond an upstream end (13a) or a downstream end (14a) of the trough (1), or- a step d) of recovering the elements (101, 103) in the upstream zone (13) or in the downstream zone (14) of the trough (1), one or more orifices being provided in the tray of the trough (1) in said upstream zone (13) and / or said downstream zone (14). Mechanical separation method according to one of the preceding claims, in which the mechanical vibration in step c) is applied to the trough (1) by means of a vibrating system (2), integral with the trough (1). Mechanical separation method according to one of the preceding claims, in which the mechanical vibration applied to the trough (1) is associated with a rectilinear movement of amplitude between 0.1 mm and 1 mm. Mechanical separation method according to the preceding claim, in which the rectilinear movement takes place along an axis inclined by 10° to 30° relative to the main plane, said axis and the longitudinal axis (A) of the trough (1) being included in a plane normal to the main plane. Mechanical separation method according to one of the preceding claims, in which the trough (1) is formed from a material chosen from steel, ceramic, quartz or silicon.

Images