Container for holding bulk material while it is being introduced into a fluid, and method for producing a container

Abstract

A description is given of a container (1) for holding bulk material, such as for example silicon fragments (3), while it is being introduced into a fluid, such as for example while it is being immersed in a liquid (5), and of a method for producing such a container. The container (1) comprises a base structure (7), which delimits a holding volume (9) of the container (1) in a lower region, and comprises a number of side walls (11), which laterally surround the holding volume (9) and are each disposed transversely in relation to the base structure (7). The base structure (7) is formed in one piece from a plate (17) and has a trapezoidal-profile-like geometry, in which some lower-lying elongated subregions (19) form depressed areas of the base structure (7), which are separated from adjacent areas of the base structure (7) by higher-lying elongated subregions (21) extending between them. The base structure (7) also has a multiplicity of through-holes (23).

Description

[0001] CONTAINER FOR COLLECTING BULK MATERIAL DURING A PLACEMENT

[0002] INTO A FLUID AND METHOD FOR MANUFACTURING A CONTAINER

[0003] FIELD OF THE INVENTION

[0004] The present invention relates to a container for receiving bulk material such as silicon fragments during introduction into a fluid, in particular immersion into a liquid or introduction into a drying gas stream, as well as a method for manufacturing such a container.

[0005] TECHNICAL BACKGROUND

[0006] A technical background and specific embodiments of the invention are explained herein using the example of processing bulk material in the form of silicon fragments, in particular immersing silicon fragments in a liquid or flushing silicon fragments with gas. However, embodiments of the invention can also be applied to other types of processing or other types of bulk material.

[0007] Silicon can be produced as a highly pure material, for example, in the form of polycrystalline, multicrystalline, or monocrystalline blocks, rods, or bars. Before further processing, these are often crushed using metallic tools such as crushers. The resulting silicon fragments, sometimes referred to as "chunks," generally must then be freed of metallic impurities before being further processed, for example, into electronic components or solar cells, where such metallic impurities could otherwise have a harmful effect.

[0008] US 6,309,467 BI, US 7,736,439 B2, and DE 10 2006 031 105 A1 describe methods for cleaning polysilicon fragments. The fragments are collected in a basket-like container and then immersed together with the container into a cleaning fluid. The container has through-holes through which the cleaning fluid can flow into an internal receiving volume of the container and thus come into contact with the fragments. The cleaning fluid can have a wetting, oxidizing, and optionally corrosive effect on the polysilicon fragments, thus freeing them from, for example, metallic contamination.

[0009] JP 2023019676 A describes the properties of a container in which the fragments can be collected during the cleaning process. JP 2012106914 A describes an alternative basket-like container in which rods to be cleaned can be collected. KR 200445846 Y1 describes another possible container design.

[0010] SUMMARY OF THE INVENTION AND EMBODIMENTS

[0011] Containers for holding bulk material, in particular silicon fragments, such as those used for immersion in a cleaning fluid during cleaning processes, are regularly subjected to heavy mechanical, thermal, and chemical stress and are therefore subject to considerable wear. As wearing parts, they must therefore be replaced frequently. The aim is therefore to be able to manufacture such containers cost-effectively and simply and, at the same time, to ensure that the containers can withstand the stresses and strains for as long as possible. The containers should also be designed in such a way that the bulk material held therein, in particular the silicon fragments held therein, can be flushed as efficiently as possible by a fluid, such as a liquid used for cleaning, and, on the other hand, the bulk material can be advantageously dried after such flushing.

[0012] There may therefore be a need for a container in which bulk material can be held during introduction into a fluid, in particular during immersion in a liquid, and which, in particular, satisfies the aforementioned requirements as well as possible. Furthermore, there may be a need for a method for manufacturing such a container, wherein the method should be as simple as possible, using the simplest and fewest tools possible, and / or as cost-effective as possible.

[0013] The aforementioned needs can be at least partially met by the subject matter of one of the independent claims of the present application. Advantageous embodiments are specified in the dependent claims as well as the following description and the accompanying figures.

[0014] According to a first aspect of the present invention, a container for holding bulk material during introduction into a fluid is described. The container has at least one base structure which delimits a holding volume of the container in a lower region, and a plurality of side walls laterally surrounding the holding volume and each arranged transversely to the base structure. The base structure is formed integrally from a plate and has a trapezoidal profile-like geometry in which some lower-lying, elongated partial regions form depressed areas of the base structure, which are separated from adjacent areas of the base structure by higher-lying, elongated partial regions extending therebetween. In addition, the base structure has a plurality of through holes.

[0015] According to a second aspect of the present invention, a method for manufacturing a container for holding bulk material during introduction into a fluid, in particular for manufacturing a container according to an embodiment of the first aspect of the invention, is described. The method comprises at least the following steps, preferably, but not necessarily, in the specified order:

[0016] Providing a plate having a plurality of through holes; introducing a plurality of linear grooves into the plate;

[0017] Forming a floor structure with a trapezoidal profile-like geometry by bending the plate along the grooves such that, with respect to a groove, adjacent partial areas of the plate run in different planes which enclose a bending angle between them, so that some lower-lying elongated partial areas form depressed areas of the floor structure which are separated from adjacent areas of the floor structure by higher-lying elongated partial areas running therebetween; and attaching side walls laterally surrounding the floor structure and each running transversely to the floor structure.

[0018] Embodiments of the invention may be considered, among other things and without limiting the invention, as being based on ideas or findings described below.

[0019] By way of introduction, a basic idea for embodiments of the invention described herein will be briefly explained, whereby this explanation is to be interpreted as merely a rough summary and not as limiting the invention:

[0020] Containers that have been used to date to hold bulk materials, such as silicon fragments, and then immerse them in a cleaning fluid, for example, generally had a box-shaped geometry with a flat bottom with a large number of holes through which the fluid could flow into a holding volume enclosed by the container. It was observed, however, that such containers with a flat bottom do not have a very high mechanical load-bearing capacity. In particular, only a limited number of relatively small holes could be provided in the flat bottom in order to prevent excessive mechanical weakening of the bottom and the escape of small silicon fragments through the holes. This, however, also prevented fluid from flowing into the container for cleaning orEtching of the silicon fragments, subsequent outflow of liquid from the container and inflow of air for final drying of the silicon fragments was inhibited.

[0021] Alternatively, containers were proposed that have a relatively complex structure and can therefore only be manufactured with significantly increased effort.

[0022] In the container described herein, the base is to have a trapezoidal profile-like geometry in which lower-lying elongated sections alternate with higher-lying elongated sections running between them. A base structure with such a trapezoidal profile-like geometry enables, on the one hand, increased mechanical stability. On the other hand, such a base structure can accommodate significantly more through-holes than in a completely flat base structure, allowing liquid or air to flow more easily into and out of the container's receiving volume through the through-holes. The base structure with the trapezoidal profile-like geometry can be formed relatively easily in one piece from a plate, so that the proposed container can be manufactured with little effort and thus cost-effectively.For this purpose, straight grooves can be created on one or both sides of the panel, along which the panel can then be bent to create the desired trapezoidal profile-like geometry. Possible features of embodiments of the invention and the advantages achieved thereby are described in detail below.

[0023] The container described herein is designed to hold bulk material, for example in the form of a large number of silicon fragments, in a holding volume enclosed by the container such that the fragments are held in the container during introduction into a fluid, for example during immersion in a liquid. The container can be designed as a basket with a base structure delimiting the holding volume at the bottom and a plurality of side walls enclosing the holding volume at the sides. For example, the base structure can have a quadrangular, in particular rectangular, outline and the holding volume can be surrounded by four side walls. The side walls can each run in planes perpendicular or oblique to a plane of the base structure. In particular, opposite side walls can run parallel to one another.Above the receiving volume, the container can be open or alternatively covered with a ceiling structure that can be reversibly opened or removed if necessary.

[0024] The container can be dimensioned such that its receiving volume can accommodate silicon fragments with a total weight of between 5 kg and 100 kg, preferably between 10 kg and 40 kg, and more preferably between 20 kg and 30 kg. For example, the container can typically have a length of between 20 cm and 2 m, preferably between 50 cm and 1 m, a width of between 10 cm and 1 m, preferably between 30 cm and 60 cm, and a height of between 10 cm and 1 m, preferably between 20 cm and 50 cm. The fragments are introduced into the container as bulk material. Individual fragments can typically have dimensions or diameters of between 0.5 cm and 20 cm, usually between 2 cm and 7 cm. The container can be introduced into a fluid, in particular a liquid or a gas, during processing of the bulk material.

[0025] The liquid into which the container, including the (silicon) fragments, is to be immersed can be a liquid, a solution, or a mixture of liquids with a cleaning, oxidizing, and / or corrosive effect. For example, the liquid can comprise water, in particular ultrapure deionized water (DI water), hydrofluoric acid (HF), nitric acid (HNO3), and / or chemical additives. The liquid can be at room temperature, i.e., approximately 20-30°C, or heated to an elevated temperature, for example, above 40°C, above 60°C, or even above 80°C, but typically below 120°C and mostly below 100°C. The liquid can also be cooled below room temperature, for example, to a temperature of 2-20°C. The material of the container that comes into contact with the liquid is selected such that it is resistant to attack by the liquid, and in particular is not chemically decomposed or etched by the liquid.

[0026] The base structure is formed integrally from a plate. In other words, during manufacture of the container, the entire base structure is preferably formed by suitable machining of a single plate. The plate may initially be flat and then machined to assume a trapezoidal profile-like geometry. For this purpose, the plate may be kinked, bent, or folded, as described in more detail below, such that several elongated portions of the plate are lower than adjacent elongated portions, with the lower portions being separated and spaced from one another by higher portions extending therebetween. Each of the lower portions and higher portions may be flat in itself. All of the lower portions may be arranged in a common plane.The higher-lying subregions can be arranged above the lower-lying subregions and thus be interpreted as projecting into the recording volume. The higher-lying subregions can all be arranged in a common plane, whereby this plane can be parallel to the common plane of the lower-lying subregions. The lower-lying subregions can be connected to the higher-lying subregions by flanks that run obliquely, i.e., for example, at an angle of between 20° and 70°, preferably between 35° and 55°, to both the lower-lying subregions and the higher-lying subregions.

[0027] A large number of through-holes are provided in the plate forming the base structure. The through-holes can be designed with any desired geometry, for example round, square, rounded, as an elongated hole or the like. The through-holes can preferably extend perpendicularly through the plate. The through-holes can have a constant cross-section along their direction of extension. For example, the through-holes can be drilled as round holes with a constant cross-section. Alternatively, the through-holes can be manufactured in a different way and, for example, be conical. The through-holes can have lateral dimensions or a diameter of typically at least 2 mm, at least 3 mm or at least 4 mm, so that liquid can easily flow through them. On the other hand, the lateral dimensions orThe diameter of the through-holes should preferably be less than 20 mm, less than 10 mm, or less than 6 mm to prevent particularly small silicon fragments from escaping from the receiving volume through these through-holes. The distance between adjacent through-holes can be less than 20 mm, less than 10 mm, or less than 6 mm. In other words, the edges of adjacent through-holes can be spaced apart by less than the stated values. Thus, the through-holes are close enough together to allow liquid to flow smoothly through the through-holes into the receiving volume. On the other hand, the distance between adjacent through-holes should be at least 2 mm, at least 4 mm, or at least 8 mm to avoid excessively weakening the stability and load-bearing capacity of the base structure due to too many or too closely spaced through-holes.The through holes can be evenly distributed along the entire plate. Alternatively, the through holes can be unevenly spaced. For example, fewer through holes can be provided in areas that are essential for the stability of the base structure or the entire container than in other areas.

[0028] According to one embodiment of the second aspect of the invention, a container, as described herein by way of example for holding silicon fragments, can be manufactured by first providing a plate with which the base structure is to be formed. The plurality of through-holes can already have been previously formed in the plate. Alternatively, such a plurality of through-holes can be introduced into the plate during the course of the method. The through-holes can advantageously be drilled into the plate before the plate is bent. Accordingly, the holes can be easily introduced into the plate, which is still flat before the plate is bent, using simple drilling tools.

[0029] A number of straight grooves are then cut into the plate. For example, the grooves can be milled, cut, laser burned, or created in some other way. The grooves form mechanical weak points in the plate along which the plate can then be bent, i.e. curved with a small radius of curvature. The depth and shape of the grooves can be adjusted in such a way that bending or curving of the plate along the grooves is made easier, but at the same time breaking or tearing of the grooves during such a bending or curving process is avoided. Accordingly, the plate remains a single piece even when bent along its grooves. Using the plate provided with these grooves, the base structure of the container can then be formed with the desired trapezoidal profile-like geometry by bending the plate appropriately along the grooves.The bending is performed in such a way that the sections of the plate adjacent to a groove on both sides are arranged at an angle to each other after bending. This angle is referred to herein as the bending angle. This allows the formation of the lower, elongated sections described above, as well as the higher, elongated sections arranged between adjacent lower sections.

[0030] Finally, side walls can be attached to the floor structure thus formed, which laterally surround the floor structure and the receiving volume to be formed above it. These side walls are aligned transversely, preferably perpendicularly, to the floor structure.

[0031] Accordingly, according to one embodiment, in a container manufactured in the manner described above, the base structure in the plate has a plurality of rectilinear grooves, wherein the plate is bent along the grooves in such a way that, with respect to a groove, adjacent partial regions of the plate run in different planes which enclose a bending angle between them.

[0032] According to one embodiment, the grooves can have a depth of at least 1 mm, preferably at least 2 mm. Alternatively or additionally, the grooves can have a depth that is at least 30%, preferably at least 50%, of the material thickness of the plate.

[0033] In other words, the grooves can be cut into the panel in such a way and to such a depth that the panel has a significantly lower material thickness in the area of ​​the grooves than the previously unprocessed panel. The grooves can be cut on just one side or on both opposite sides of the panel. Since the panel is considerably thinner in the area of ​​the grooves than in adjacent areas, the grooves represent mechanical weak points. In addition, since the grooves are straight and preferably extend along the entire length or width of the panel, i.e. from one edge of the panel to an opposite edge of the panel, the panel will give way and deform primarily in the area of ​​the grooves when subjected to a bending load. Accordingly, the grooves can serve as folded edges, i.e. the panel can be bent in a defined manner along the grooves.However, the depth of the grooves should generally be less than 90% or even less than 80% of the material thickness of the board in order to prevent excessive weakening of the board or even breaking or cracking of the board along the grooves.

[0034] According to one embodiment, the grooves have an outwardly widening cross-section and / or a width that is greater than a depth of the grooves.

[0035] In other words, the grooves can be formed with a conical cross-section, i.e. wider at a surface of the plate than deeper inside the plate. Alternatively, the grooves can have a different cross-sectional shape, such as a rectangular or quasi-rectangular cross-section. The grooves can have a width that is greater than their depth. The width can be measured as the average width, maximum width, or width in the area of ​​the surface of the plate. All grooves provided in the plate can have the same cross-sectional shape. Alternatively, the grooves can have different cross-sectional shapes depending on an intended bending direction and / or an intended bending angle.

[0036] The two individual measures mentioned above, or a combination of both measures, can (as explained in more detail below with reference to the figures) contribute to the ability of the plate, among other things, to be bent along the groove without cavities forming in the groove region, from which, for example, liquid could only flow with a delay. According to one embodiment, the bending angle by which adjacent subregions of the plate are angled relative to one another can be between 20° and 70°, preferably between 35° and 55°.

[0037] It was recognized that a floor structure with a trapezoidal profile-like geometry, in which adjacent sections are angled relative to each other at the aforementioned angles, exhibits significantly increased mechanical load-bearing capacity compared to flat plates, with the load-bearing capacity typically increasing with increasing bending angle. On the other hand, it was recognized that at such bending angles, there is a low risk of silicon fragments becoming caught or jammed in the areas adjacent to the bend in the sections of the plate that are angled to each other.

[0038] According to one embodiment, the plate has a material thickness of at least 3 mm, preferably at least 4 mm, and at most 20 mm, at most 10 mm or at most 6 mm.

[0039] The plate used to form the floor structure is thus sufficiently thick to avoid excessive distortion under load, yet thin enough to keep the container's dead weight low. Despite its low weight and minimal material requirements, a floor structure made of such a relatively thin plate can withstand considerable loads, particularly due to its three-dimensional, trapezoidal-shaped geometry.

[0040] According to one embodiment, the base structure and / or the side walls are made of plastic, in particular polyvinylidene difluoride (PVDF).

[0041] The use of plastic for the base structure and / or the side walls can be advantageous, on the one hand, due to the high chemical resistance of many plastics to aggressive liquids such as corrosive and / or oxidizing liquids. On the other hand, many plastics are relatively easy to process and / or inexpensive to obtain. In particular, PVDF has proven particularly suitable for the production of the containers described herein due to its chemical and mechanical properties. PVDF typically exhibits high chemical stability, good dimensional stability, and high thermal resistance. Furthermore, PVDF can be produced in high degrees of purity and is recyclable as a thermoplastic. It exhibits hydrophobic properties, which can reduce carryover. Furthermore, PVDF is a weldable material.

[0042] According to one embodiment, the lower elongated partial regions are flat and have a width of at least 2 cm, preferably at least 3 cm, and at most 15 cm, preferably at most 8 cm.

[0043] Designing the lower sections of the soil structure with a maximum width of 15 cm can, on the one hand, contribute to ensuring that the entire soil structure achieves sufficiently high mechanical stability due to the reinforcing higher sections, which run at relatively short distances between adjacent lower sections. On the other hand, ensuring that the sections have a width of at least 2 cm can minimize the risk of (silicon) fragments becoming entangled or jammed within narrower lower sections.

[0044] According to one embodiment, the container further comprises at least one reinforcing rib which runs in a direction transverse to the elongated partial regions of the base structure and which supports the base structure from below outside the receiving volume.

[0045] The reinforcing rib serves to increase the mechanical stability and rigidity of the entire floor structure. The reinforcing rib preferably extends along the entire floor structure, i.e., from one edge of the floor structure to an opposite edge thereof. The reinforcing rib can be attached or fixed to the floor structure and / or to the side walls, which are arranged adjacent to said opposite edges, as a separate component, for example by form-fitting cooperation and / or material-to-material fixing. The reinforcing rib can be made of the same or a similar material, in particular a plastic material, as the floor structure and / or the side walls. The reinforcing rib can have a geometry that is complementary to the trapezoidal profile-like geometry of the floor structure.

[0046] According to one embodiment, the edges of the base structure can engage, at least in part, in a receiving groove formed in the inner side of a respective one of the side walls, and can additionally be integrally connected, i.e., welded, to the respective side wall along the receiving groove. In this case, an embodiment of the manufacturing method according to the invention further comprises forming the receiving groove on the inner sides of at least two opposite side walls, inserting edges of the base structure, at least in part, in a positive-fitting manner into the receiving groove of a respective side wall adjacent to the edge, and integrally connecting, in particular welding, the base structure along the receiving groove to the adjacent side wall.

[0047] In other words, the base structure can, on the one hand, interact in a form-fitting manner with the surrounding side walls and, on the other hand, can also be additionally materially bonded to the side walls, for example, by welding or adhesive bonding. For this purpose, a groove-like recess can be provided in each of the side walls, into which the base structure can be inserted with its edge or at least with parts of its edge, thus engaging positively with the side wall. Due to the form-fitting connection, considerable forces can be transferred between the side wall and the base structure, thus ensuring high stability of the container. This stability can be further increased by additionally bonding the base structure to the side walls in a material-fitting manner, in particular by welding or adhesive bonding.The integral connection prevents, among other things, the base structure from being pulled out of its positive engagement with the side wall. In addition, and for the specific application of the container described here, in which it is intended to be immersed in potentially aggressive liquids, the additional integral connection of the base structure to the side plate can prevent, for example, any cavities present at the transition between the base structure and the groove in the adjacent side wall from being temporarily flooded with liquid or from liquid being drawn into the cavities by capillary action. This liquid may then be unable to drain from the cavities or may only drain slowly, and thus, for example, be carried over in an unintentional manner.Instead, the material-to-material connection of the base structure to the side wall along the groove results in a liquid-tight closure or sealing of the transition between the two components, thus preventing liquid from penetrating into any cavities.

[0048] According to one embodiment, the container has a plurality of rods which connect opposite side walls to one another.

[0049] In other words, in addition to the side walls and the base structure, the container can have several rods extending between at least two of the opposing side walls. Forces can then be transferred between the two side walls via such rods. In particular, the two side walls can be subjected to tensile forces toward each other using the rods. In this way, the base structure located between the two side walls can be clamped between the side walls. The rods can be used to significantly stiffen and stabilize the container, allowing it to withstand high loads.In particular, the rods can be used to transfer forces between the side walls connected by them, thus protecting the other side walls extending between the respective side walls and the floor structure extending there from the effects of excessive forces. Furthermore, the rods can help maintain basic tolerances of the container.

[0050] The side walls to be connected by the rods can be those side walls of the container that are arranged parallel to the elongated sections of the base structure and are referred to below as transverse side walls. In this case, the rods run transversely, preferably perpendicularly, to the elongated sections or to the grooves in the plate of the base structure.

[0051] Alternatively or additionally, bars can connect those side walls that extend transversely to the elongated sections of the floor structure and which are hereinafter referred to as longitudinal side walls.

[0052] Preferably, the rods are arranged outside the receiving volume, i.e. outside the side walls delimiting the receiving volume.

[0053] According to one embodiment, the rods are made of carbon. In particular, the rods can be made of carbon or a carbon fiber-reinforced plastic (CFRP), such as carbon fiber-reinforced PVDF. Alternatively or additionally, the rods can be coated with plastic. For example, the rods can be metal rods, in particular steel rods, coated with a protective plastic, for example in the form of a layer of ECTFE (Halar®). As a further alternative or additionally, the rods can engage positively with the opposing side walls.

[0054] Carbon rods can withstand particularly high forces, thus giving the container exceptional stability. Carbon rods also generally exhibit sufficiently high chemical resistance to the aggressive liquids the container is intended to contain.

[0055] Coating the rods with plastic can protect the rod surface, particularly from external forces and / or chemical attack. For example, carbon rods can be protected from excessive stress concentrations. Rods made of materials that are not sufficiently chemically resistant can be protected from contact with chemically aggressive media. Furthermore, the coating can prevent rod material from detaching from the rods and / or components or additives such as plasticizers from escaping and, for example, entering the cleaning fluid in which the container is immersed, thereby contaminating it.

[0056] By designing the rods and the side walls to be connected by them in such a way that the rods engage positively with the side walls, high forces can be transferred between the side walls using the rods.

[0057] According to one embodiment, the side walls are free of through holes at least in a lower region of at least 50%, preferably at least 80% or even along 100% of a height of the receiving volume.

[0058] In other words, in contrast to the base structure, the side walls are preferably free of through-holes at least in a lower region. More preferably, the side walls are completely free of through-holes. In particular, the side walls can be formed using flat, continuous plates. Accordingly, fluids coming from below can flow exclusively through the through-openings in the base structure into the receiving volume enclosed by the container. This property can be particularly advantageous during a drying process that follows the immersion of the container in liquid. During such a drying process, gas, in particular air, can be flowed through the receiving volume of the container in order to dry the silicon fragments located there.The container can preferably be arranged on a device that generates a suitable gas flow in such a way that the drying gas can flow into the receiving volume over a large area at the bottom of the container through the through-holes in its base structure. If the side walls are free of holes, the gas must then flow completely through the receiving volume and thus along all the silicon fragments received there before it can exit the receiving volume again on a side of the container opposite the base structure. In this way, it can be ensured that the entire bulk material held in the container is efficiently flowed around and dried by the gas flow. The same principle also applies to the flow of a liquid around the bulk material, which is also described herein.

[0059] Furthermore, side walls that are largely or completely free of through-holes and that are also preferably flat at least on their inner side facing the receiving volume are advantageous in that no silicon fragments can become trapped in through-holes and / or irregularities when the container is emptied. The silicon fragments located in the container can thus be easily and residue-freely poured out of the container at the end of a liquid treatment and possibly after subsequent drying.

[0060] It should be noted that possible advantages and configurations of embodiments of the invention are described herein partly with reference to a container according to the invention and partly with reference to a method for manufacturing a container. A person skilled in the art will recognize that the described features can be appropriately transferred, adapted, exchanged, or modified to achieve further embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Embodiments of the invention are described below with reference to the accompanying drawings, wherein neither the drawings nor the description are to be construed as limiting the invention.

[0062] Fig. 1 shows a perspective view of a container according to an embodiment of the invention.

[0063] Fig. 2 shows a side view of a transverse side wall of the container from Fig. 1.

[0064] Fig. 3 shows a longitudinal sectional view through the container of Fig. 1 along a plane AA as indicated in Fig. 2.

[0065] Fig. 4 shows a top view of the container from Fig. 1.

[0066] Fig. 5 shows a perspective detailed view of the container from Fig. 1.

[0067] Fig. 6 shows the perspective detail view from Fig. 5 omitting the floor structure.

[0068] Fig. 7 shows a side view of a plate of a bottom structure of the container from Fig. 1 before buckling.

[0069] Fig. 8 shows a side view of a plate of a bottom structure of the container from Fig. 1 after buckling.

[0070] Fig. 9 illustrates a cleaning of polysilicon fragments in a container according to the invention.

[0071] Fig. 10 illustrates the drying of polysilicon fragments in a container according to the invention. Fig. 11 illustrates the emptying of polysilicon fragments from a container according to the invention.

[0072] The figures are merely schematic and not to scale. The same reference numerals designate identical or equivalent features in the various figures.

[0073] DESCRIPTION OF PREFERRED EMBODIMENTS

[0074] Fig. 1 shows a container 1 in which silicon fragments 3 can be held while immersed in a liquid 5 in the form of a cleaning fluid or etching fluid (see Fig. 9). The container 1 comprises a base structure 7 and a plurality of side walls 11 in the form of two opposing longitudinal side walls 13 and two opposing transverse side walls 15, which together surround a receiving volume 9.

[0075] Figures 2-4 show a view of the transverse side wall 15, a sectional view through the container 1, and a plan view of the container 1. Figures 5 and 6 show two detailed views. Figures 7 and 8 show a plate 17, by means of which the base structure 7 is formed, before and after folding into a trapezoidal profile-like geometry.

[0076] The floor structure 7 consists of a one-piece plate 17 made of PVDF with a material thickness of 4 mm and a trapezoidal profile-like geometry. The trapezoidal profile-like geometry is formed by introducing straight grooves 25 into the plate 17, which have a depth of approximately 2-3 mm and which run transversely across the entire width of the plate 17. Along these grooves 25, the plate 17 is then alternately bent twice in a first direction and twice in an opposite direction at equal bending angles in order to create the trapezoidal profile-like geometry. In the example shown, the bending angle is 45°. Several lower-lying, elongated partial regions 19, which extend in the transverse direction, form depressed areas of the floor structure 7. Adjacent lower-lying, elongated partial regions 19 are separated from one another by higher-lying, elongated partial regions 21 running between them.Higher-lying sections 21 and lower-lying sections 19 thus alternate. The lower-lying sections are flat and have a width (i.e., a dimension in the longitudinal direction of the container) of approximately 4-6 cm. The higher-lying sections are also flat and, in the example shown, also have a width of approximately 4-6 cm, but could also have a considerably smaller width.

[0077] As can be seen in Figures 7 and 8, the grooves 25 can have a rectangular cross-section or an outwardly widening cross-section. The width of the grooves 25 is preferably selected such that, after the plate 17 is bent, the flanks of the grooves 25 do not abut one another, thus preventing closed cavities from forming along the grooves and allowing fluid to escape from the grooves quickly and easily. For this purpose, the depth of the grooves 25 can, in particular, be smaller than their width.

[0078] Throughout the entire base structure 7, many through-holes 23 are provided through which liquid can flow into the receiving volume 9 when the container 1 is immersed and can then flow out again. In the example shown, the through-holes 23 are round and have a diameter of 4 mm. Through-holes 23 are provided along the entire surface of the plate 17, with the exception of the areas in which the grooves 25 run. The through-holes 23 are evenly distributed along the surface and can be arranged equidistant from one another. Advantageously, the through-holes 23 can already be drilled before the plate 17 is bent, so that all through-holes 23 can be easily drilled in the same direction and do not need to be drilled at an angle to a surface of the plate 17.In order to protect the base structure 17, in particular against bending due to the considerable load generated by the silicon fragments, a reinforcing rib 29 runs below the base structure 17 and outside the receiving volume 9 in the longitudinal direction of the container and thus transversely to the elongated partial regions 19, 21 of the base structure 7. In the example shown, the reinforcing rib 29 is formed on its upper edge directed towards the base structure 7 with a trapezoidal profile-like geometry which can be applied approximately complementarily to the geometry of the base structure 7.

[0079] As can be seen in Figures 5 and 6, a receiving groove 33 is provided on each inner side of the longitudinal side walls 13 and possibly also of the transverse side walls 15. The course of this receiving groove 33 corresponds to the trapezoidal profile-like geometry of the base structure 7, so that edges 31 of the base structure 7 can each be positively inserted into the receiving groove 33 on the adjacent side walls 11. In addition, the areas adjacent to these edges 31 are then materially connected to the respective side wall 11, for example by welding, in order to thereby seal off any cavities that could otherwise remain within the receiving grooves 33 and in which liquid could collect.

[0080] Furthermore, the transverse side walls 15 are connected to one another via several rods 35 that increase stability. The rods 35 are made of carbon and impart very high stability to the entire container by acting as a type of frame together with the transverse side walls 15. To protect the rods 35, in particular from notch forces, they can be coated with a thin layer of softer plastic. The rods 35 can engage positively with the opposing transverse side walls 15 and thus transmit high forces to them. In contrast to the base structure 7, the side walls 11 are free of through holes, at least in a lower region or, as in the example shown, along their entire height.

[0081] As illustrated in Figure 9, a plurality of silicon fragments 3 can be received as bulk material in the receiving volume 9 of the container 1 and then immersed in a basin filled with liquid 5. The liquid 5 flows through the through-holes 23 from below through the base structure 7 and washes around the silicon fragments 3. The container 1 can then be moved up and down several times, as indicated in the figure by opposite arrows, in order to ensure that all of the silicon fragments 3 are evenly washed. After the silicon fragments 3 have been cleaned in this way and possibly etched off on the surface, the container 1 is removed from the basin, whereby the liquid 5 can flow out through the perforated base structure 7.

[0082] Subsequently, as illustrated in Figure 10, the container 1 is connected to a drying device 37, which directs a hot air stream 39 through the receiving volume 9 of the container 1. A housing of the drying device 37 is designed and dimensioned such that it is largely sealed against the side walls 11. Since the side walls 11 are continuous and free of through holes, the air stream 39 generated by the drying device 37 is forced to flow through the entire bulk material of the silicon fragments 3, thus drying them efficiently.

[0083] Finally, the silicon fragments 3 can be emptied from the container 1, as shown in Figure 11. It is again advantageous that the longitudinal side walls 13 are free of through holes and flat, so that the silicon fragments 3 can easily slide out of the receiving volume 9. The following explains the background and ideas for the container described herein, its production, and possible configurations thereof again using different terminology.

[0084] In a container, silicon fragments (so-called polychunks) are transported through various process areas of a wet chemical plant using a handling system. The process areas are primarily basins filled with liquid media, into which the container is placed by the handling system. A handling gripper can hook into a contour of side plates. There is also a dryer, where the polychunks are dried using hot air. Most polychunks have a diameter of between 20 and 70 mm. The polychunks are distributed as bulk material in the container; the bulk material weighs approximately 25 kg. Handles in the container side plate also allow manual transport outside the plant.

[0085] Container in a liquid medium: After the container has been placed in the filled basin by the handling device, it is moved up and down within the medium by a lifting unit integrated into the basin. The medium enters the interior of the container through the perforated base plate. The up and down movement distributes the medium within the container and surrounds the polychunks. The side walls of the container are closed. The distribution of the medium in the bulk material causes etching and cleaning processes to take place on the polychunks.

[0086] Container in the dryer: The container is placed on supports within the dryer. The container's mounting and design allow hot air to flow almost completely through the process material. Nothing flows past the container.

[0087] Automated tipping: A lower foot bar automatically tilts the container approximately 135°, allowing the bulk material to be tipped out over one of the longitudinal side panels. The following problems are to be solved:

[0088] The perforated vessel bottom should ensure good flow of the liquid medium through the process material. At the same time, the diameter of the holes in the vessel bottom must not be too large, as otherwise process material could be lost.

[0089] The aim is to achieve good distribution of the liquid medium in the process material. The aim is to achieve good flow of hot air through the process material in the dryer. Hot air in the dryer must not be able to flow unused past the container. The container should be as simple as possible in terms of manufacturing and the amount of material used. The container should be resistant to the media used. Media carryover through the container should be avoided as much as possible. The base must be able to withstand the weight of the bulk material. When the bulk material is tipped over the long side, the loaded side of the container must be designed to withstand this load and so that no bulk material gets caught on interfering contours (the container should be capable of being almost completely emptied automatically). The container must be metal-free.

[0090] The problems are mainly solved by the design of the container and the choice of materials as follows:

[0091] Base structure: A flattened version of the container's perforated base plate has cutouts in the form of grooves. These cutouts act as folded edges. When the base is folded over these folded edges, a base shape with trapezoidal recesses is created. The holes have a diameter of 4 mm. This minimizes waste during the transport of polychunks. To achieve good flow, a large number of these holes are required.

[0092] The trapezoidal design of the base allows for a much higher number of holes compared to a flat plate, as holes are also present on the sloped sides of the trapezoids. The total entry cross-section for the medium into the container, i.e., the sum of all the cross-sections of the holes, is thus larger. The recesses result in better media distribution in the bulk material. Furthermore, the trapezoidal shape makes the base stable, similar to the triangular shape of a truss. This results in less deflection.

[0093] The container can have the following overall structure:

[0094] The longitudinal side plates feature cutouts into which the trapezoidal floor is inserted. This creates a positive fit. A welded joint is relieved of stress. The longitudinal side plates, in turn, are inserted into the front and rear side plates using the same principle. Additionally, there are ribs beneath the trapezoidal floor. The front and rear side plates are connected by four carbon rods. The carbon rods are encased in a plastic sheath and are also inserted into the side plates with a positive fit.

[0095] This construction of form-fitting parts and carbon rods enables a stable container.

[0096] PVDF is the preferred plastic material. This material has high chemical resistance.

[0097] By designing the trapezoidal base as a folded part, the production of the containers is less time-consuming. If the trapezoidal base were welded together from individual pieces, much more welding would be required.

[0098] The raw plate of the trapezoidal floor can be machined from one side on a milling machine, eliminating the need for time-consuming re-clamping. The finisher can then use the trapezoidal milling of the side plate and the trapezoidal milling of the ribs as a guide when assembling the trapezoidal floor with the side plates. After assembly, the individual parts are welded together.

[0099] The folding base plate design also has the advantage that the holes can be easily drilled into the flat plate before folding. Drilling into the trapezoidal flanks would be very laborious, as drilling would have to be done at an angle.

[0100] The container is chamfered as far as possible on all parts to allow the medium to drain from all surfaces. The folds in the groove area are wide open, even after folding, so that no medium can become trapped and spread.

[0101] The following advantages are achieved, among others:

[0102] - Optimization of process results (etching and cleaning)

[0103] - Optimized drying of the bulk material - Lower flow resistance when immersed in the medium

[0104] - Lower production costs

[0105] - Stable construction

[0106] Finally, it should be noted that terms such as "having," "comprising," etc., do not exclude other elements or steps, and terms such as "a" or "an" do not exclude a plurality. Furthermore, it should be noted that features or steps described with reference to one of the above embodiments may also be used in combination with other features or steps of other embodiments described above. Reference signs in the claims are not to be considered as limitations.

[0107] LIST OF REFERENCE SYMBOLS

[0108] I Container

[0109] 3 silicon fragments

[0110] 5 Liquid

[0111] 7 Soil structure

[0112] 9 Recording volume

[0113] II Side wall

[0114] 13 Longitudinal side wall

[0115] 15 Transverse side wall

[0116] 17 plate

[0117] 19 deeper sub-areas

[0118] 21 higher sub-areas

[0119] 23 through holes

[0120] 25 grooves

[0121] 27 bending angles

[0122] 29 Reinforcing rib

[0123] 31 edge

[0124] 33 mounting groove

[0125] 35 bars

[0126] 37 Drying device

[0127] 39 Airflow

Claims

Claims:

1. A container (1) for receiving bulk material, in particular in the form of silicon fragments (3), during introduction into a fluid, in particular during immersion in a liquid (5), wherein the container (1) comprises: a base structure (7) which delimits a receiving volume (9) of the container (1) in a lower region, and a plurality of side walls (11) laterally surrounding the receiving volume (9) and each arranged transversely to the base structure (7), wherein the base structure (7) is formed in one piece from a plate (17) and has a trapezoidal profile-like geometry, in which some lower-lying elongated partial regions (19) form depressed areas of the base structure (7), which are separated from adjacent areas of the base structure (7) by higher-lying elongated partial regions (21) extending therebetween, and wherein the base structure (7) has a plurality of through-holes (23).

2. Container according to claim 1, wherein the base structure (7) in the plate (17) has a plurality of straight grooves (25), wherein the plate (17) is bent along the grooves (25) in such a way that, with respect to a groove (25), adjacent partial regions (19, 21) of the plate (17) run in different planes which enclose a bend angle (27) between them.

3. Container according to claim 2, wherein the grooves (25) have a depth of at least 1 mm and / or wherein the grooves (25) have a depth which is at least 30% of a material thickness of the plate (17).

4. Container according to one of claims 2 and 3, wherein the grooves (25) have an outwardly widening cross-section and / or a width which is greater than a depth of the grooves (25).

5. Container according to one of claims 2 to 4, wherein the bending angle (27) is between 20° and 70°.

6. Container according to one of the preceding claims, wherein the plate (17) has a material thickness of at least 3 mm and at most 20 mm.

7. Container according to one of the preceding claims, wherein the base structure (7) and / or the side walls (11) consist of plastic, in particular of polyvinylidene difluoride.

8. Container according to one of the preceding claims, wherein the lower elongated portions (19) are flat and have a width of at least 2 cm and at most 15 cm.

9. Container according to one of the preceding claims, further comprising a reinforcing rib (29) which runs in a direction transverse to the elongated partial regions (19, 21) of the base structure (7) and which supports the base structure (7) from below outside the receiving volume (9).

10. Container according to one of the preceding claims, wherein the bottom structure (7) with its edges (31) each in a receiving groove (33) which is introduced into an inner side of a respective one of the side walls (11) is, engages at least partially in a form-fitting manner and is additionally materially connected along the receiving groove (33) to the respective side wall (11).

11. Container according to one of the preceding claims, further comprising a plurality of rods (35) which connect opposite ones of the side walls (11) to one another.

12. Container according to claim 11, wherein the rods (35) are formed with carbon, are coated with plastic and / or engage positively into the opposite side walls (11).

13. Container according to one of the preceding claims, wherein the side walls (11) are free of through holes (23) at least in a lower region of at least 50% of a height of the receiving volume (9).

14. A method for manufacturing a container (1) for receiving bulk material, in particular in the form of silicon fragments (3), during introduction into a fluid, in particular during immersion in a liquid (5), in particular for manufacturing a container (1) according to one of the preceding claims, the method comprising: Providing a plate (17) having a plurality of through holes (23); Introducing a plurality of straight grooves (25) into the plate (17); forming a floor structure (7) with a trapezoidal profile-like geometry by bending the plate (17) along the grooves (25) in such a way that, with respect to a groove (25), adjacent partial areas (19, 21) of the plate (17) run in different planes, which enclose a bending angle (27) between them, so that some lower-lying elongated partial regions (19) form recessed areas of the floor structure (7), which are separated from adjacent areas of the floor structure (7) by higher-lying elongated partial regions (21) extending therebetween; and attaching side walls (11) laterally surrounding the floor structure (7) and each extending transversely to the floor structure (7).

15. The method of claim 14, wherein the method further comprises: Forming a receiving groove (33) on the inner sides of at least two opposite side walls (11); at least partially inserting edges (31) of the base structure (7) into the receiving groove (33) of a side wall (11) adjacent to the edge (31); and materially connecting the base structure (7) along the receiving groove (33) to the adjacent side wall (11).

16. Method according to one of claims 14 and 15, wherein the through holes (23) are drilled into the plate (17) before the plate (17) is bent.

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