Passivation of scrap metal powder

Abstract

Aspects of passivating waste metal streams are provided. An apparatus may include a 3D printer that generates waste powder during 3D printing of a printed part, a passivator configured to receive and melt the waste powder, and a container configured to collect the molten waste powder. A method may include generating waste powder during 3D printing of a printed part, collecting the waste powder in a passivator, heating the passivator to melt the waste powder, and collecting the molten waste powder. Aspects of this disclosure may include the passivator maintaining an inert environment.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of U.S. Patent Application No. 63 / 601,992, filed November 22, 2023, entitled “WASTE METAL POWDER PASSIVATION”, the entire contents of which are expressly incorporated herein by reference, as set forth herein. Technical Field

[0003] This disclosure relates generally to additive manufacturing, and more specifically to systems and methods for passivating scrap metal streams during additive manufacturing. Background Technology

[0004] Powder bed fusion (PBF) and directed energy deposition (DED) 3D printing systems operate by melting metal powders in an inert atmosphere, such as argon or nitrogen, to create solid 3D printed structures. Metal powders (such as aluminum) react readily with oxygen and pose a potential explosion hazard when exposed to environments containing air or moisture. When the particle size is small enough, the mass-to-surface-area ratio becomes minimal, causing most of the aluminum material to transform into oxides. This makes the small powder highly flammable, capable of being ignited and burned in air. Pure aluminum can have a combustion temperature as low as 650 degrees Celsius. Rapid combustion can produce large amounts of gaseous material, which can explode in a confined space.

[0005] During the 3D printing process, by ensuring the process takes place in an inert environment, the possibility of metal powder reacting with oxygen to trigger runaway oxidation or moisture reactions is eliminated. Therefore, the melting of the powder and the subsequent solidification of the molten material into the structure do not produce potentially catastrophic reactions. After the printing process is complete and the printed structure is separated from the waste powder, the printed structure can be exposed to normal atmospheric conditions without the risk of a catastrophic reaction. However, unused waste powder remains and continues to be at risk of triggering hazardous oxidation reactions. Collecting waste powder in, for example, waste metal containers still carries a reaction risk because, during transfer from the 3D printing system and disposal of the waste metal containers, the waste powder may still trigger oxidation reactions when it moves outside the inert environment.

[0006] Therefore, it is necessary to safely passivate the waste metal powder generated during the 3D printing process to prevent dangerous oxidation reactions caused by the waste powder. Summary of the Invention

[0007] Several aspects of waste metal powder passivation equipment and methods will be described more fully below.

[0008] In one aspect of this disclosure, an apparatus for passivating waste metal powder is provided. The apparatus includes a 3D printer that generates waste powder during 3D printing of a part. The apparatus also includes a passivator configured to receive and melt the waste powder. The apparatus further includes a container configured to collect the molten waste powder.

[0009] In one or more embodiments, the device further includes a pump configured to circulate an inert gas through the device to form a gas flow carrying waste powder. For example, the gas flow may be continuous. Furthermore, the passivator of the device can receive the gas flow carrying waste powder.

[0010] In one or more embodiments, the device further includes a filter element. The filter element can be heated. For example, the passivator can be induction heated. Furthermore, the passivator of the device can be configured to receive the filter element and melt it.

[0011] In one or more embodiments, the apparatus further includes a rotating mechanism for rotating the passivator. In one or more embodiments, the apparatus further includes a cyclone separator. In one or more embodiments, the apparatus further includes a dehumidifying dryer.

[0012] In one or more embodiments, the passivator of the device further includes an electrostatically charged portion. In one or more embodiments, the passivator of the device further includes an outlet.

[0013] In another aspect of this disclosure, a method for passivating waste powder is proposed. The method includes generating waste powder by a 3D printer during 3D printing of a printed part. The method further includes collecting the waste powder in a passivator. In one or more embodiments, the passivator includes a filter element for collecting the waste powder. Furthermore, the method includes heating the passivator to melt the waste powder. Additionally, the method includes collecting the molten waste powder. In one or more embodiments, the molten waste powder is collected through an outlet of the passivator. In one or more embodiments, the passivator maintains an inert environment. For example, the inert environment may be argon or nitrogen.

[0014] In one or more embodiments, the method includes circulating an inert gas to a 3D printer to form a gas flow carrying waste powder. Additionally, the method may include conveying the gas flow carrying waste powder to a passivator.

[0015] In one or more embodiments, the method includes applying an electrostatic charge to the gas flow to attract waste powder to a passivator, wherein the passivator includes an electrostatically charged portion. In one or more embodiments, the method includes centrifugally rotating the passivator to separate the waste powder from the gas flow. In one or more embodiments, the method includes conveying the gas flow to a cyclone separator to remove coarse waste powder particles. In one or more embodiments, the method includes recirculating the gas flow to a dehumidifying dryer. In one or more embodiments, the method includes recirculating the gas flow to a 3D printer.

[0016] In one or more embodiments, the method includes melting the filter element together with collected waste powder. In one or more embodiments, the method includes melting a passivator.

[0017] In another aspect of this disclosure, the method includes generating waste powder during 3D printing of a part by a 3D printer. The method further includes circulating an inert gas to the 3D printer to generate a gas flow carrying the waste powder. Additionally, the method includes conveying the gas flow carrying the waste powder to a passivator. Furthermore, the method includes agitating the gas flow carrying the waste powder to generate a waste powder slurry. The method also includes collecting the waste powder slurry from the outlet of the passivator. In one or more embodiments, the passivator contains an aqueous solution.

[0018] In another aspect of this disclosure, the method includes generating waste powder during 3D printing of a part using a 3D printer. The method further includes circulating an inert gas to the 3D printer to generate a gas flow carrying the waste powder. Additionally, the method includes conveying the gas flow carrying the waste powder to a passivator. Furthermore, the method includes mixing the waste powder with a reactant to solidify the waste powder. The method also includes collecting the inert gas from the outlet of the passivator.

[0019] Other aspects will become apparent to those skilled in the art from the following detailed description, wherein only a few exemplary embodiments are shown and described by way of illustration. As those skilled in the art will appreciate, the concepts described herein can have other and different embodiments, and several details can be modified in various other ways without departing from this disclosure. Therefore, the accompanying drawings and detailed description are to be regarded as illustrative in nature and not restrictive. Attached Figure Description

[0020] The various aspects of the concepts described herein will now be presented in detail, by way of example rather than limitation, with the accompanying drawings, in which:

[0021] Figure 1An apparatus for passivating waste powder is shown according to one or more embodiments of this document.

[0022] Figure 2 An apparatus for passivating waste powder is shown according to one or more embodiments of this document.

[0023] Figure 3 An apparatus for passivating waste powder is shown according to one or more embodiments of this document.

[0024] Figure 4A and Figure 4B An apparatus for passivating waste powder is shown according to one or more embodiments of this document.

[0025] Figures 5A-5B This is a flowchart illustrating a method for passivating waste powder according to one or more embodiments of this document.

[0026] Figure 6 This is a flowchart illustrating a method for passivating waste powder according to one or more embodiments of this document.

[0027] Figure 7 This is a flowchart illustrating a method for passivating waste powder according to one or more embodiments of this document. Detailed Implementation

[0028] The detailed description set forth below with reference to the accompanying drawings is intended to provide a description of various exemplary embodiments of the concepts disclosed herein, and is not intended to represent the only embodiments that may be practiced with respect to this disclosure. The term “exemplary” as used herein means “serves as an example, instance, or illustration” and should not necessarily be construed as being preferred or advantageous relative to other embodiments presented herein. The detailed description includes specific details for the purpose of providing a thorough and complete disclosure that fully communicates the scope of the concepts to those skilled in the art. However, this disclosure may be practiced without these specific details. In some instances, well-known structures and components may be shown in block diagram form or omitted entirely to avoid obscuring the various concepts presented herein. Dashed lines are used in the figures to indicate elements that may be optional.

[0029] While this disclosure generally relates to laser-based PBF (L-PBF) or DED systems, it will be understood that such systems can encompass a wide variety of AM technologies. Therefore, additive manufacturing processes can include, but are not limited to, the following printing technologies: Direct Metal Laser Sintering (DMLS), Selective Laser Melting (SLM), and Selective Laser Sintering (SLS). Other additive manufacturing processes capable of melting powder during the printing process, relevant to the principles of this disclosure, include those currently conceived or under commercial development. For example, powder can be heated by induction, heating coils, lasers, flames, and any other heating method available in the art. While specific details of each such process are omitted to avoid unduly obscuring the key concepts of this disclosure, it will be understood that the claims are intended to cover such technologies and related structures.

[0030] During the additive manufacturing of the structure, waste metal powder is generated during the laser beam-induced melting of the 3D printer. During printing, waste metal powder is generated in at least two ways: (1) unused powder from the powder bed of the 3D printer; and (2) powder collected as condensate by the filter cartridge during printer operation.

[0031] Waste metal powder (including powder generated as waste from the 3D printing process) is an extremely hazardous material that can trigger a runaway oxidation reaction if exposed to air and / or moisture, generating heat and hydrogen gas. Furthermore, the risk of oxidation increases as the filter collects more waste powder. To minimize the danger from oxidation reactions, waste metal powder generated during the 3D printing process must be removed from the area where the 3D printed structure is being printed. Collecting large amounts of waste powder for removal from the 3D printing area poses a hazardous situation to personnel and facilities, potentially leading to fire and catastrophic explosion risks.

[0032] Solutions for removing waste metal powder can include batch removal of the powder away from its source. Batch processing involves collecting the powder in filter cartridges and dedicated containers, then transferring it to a remote storage and processing location where it can be passivated, for example, by receiving water in a controlled manner. However, even when transferred to a remote storage and processing location, these solutions still carry a risk of oxidation before the powder is passivated. Oxidation reactions can still occur when large quantities of waste powder are collected before it is removed from the 3D printing area for transport, and this risk may be higher because the powder has not been passivated. Fine metal powder is a potential hazard, and the larger the volume and the finer the powder, the greater the potential damage to people and facilities when collected for downstream processing, which could occur during a runaway oxidation incident. Additionally, batch processing solutions may require transporting the powder from the 3D printing location to a specific processing location. The longer the powder remains outside an inert, dry gas environment, the greater the chance of an oxidation event. Therefore, the collected waste powder may need to be continuously monitored to ensure that a sufficient amount of oxidation does not occur, leading to a runaway reaction.

[0033] Therefore, this disclosure provides solutions to mitigate the risks associated with the handling of waste metal powder in a safe and feasible manner. In particular, this disclosure provides solutions for handling waste metal powder without the need for bulk collection, handling, and disposal. In one or more embodiments herein, the disclosed solutions include passivating the generated waste powder on-site during 3D printing, which prevents the accumulation of such waste metal powder. As disclosed herein, passivation refers to treating the waste powder to reduce the likelihood of oxidation reactions.

[0034] In one aspect, this disclosure provides apparatus and methods for passivating waste powder during or after the printing process by melting and subsequently solidifying it in an inert gas environment. Passivation is performed in or near the 3D printer in an inert environment, which passivates the waste powder during collection. Furthermore, the passivation of the resulting waste metal powder can be performed in small amounts, ideally continuously or nearly continuously during or after the 3D printing process, thereby minimizing the potential for damage from any catastrophic event during waste powder generation. In one or more embodiments, the inert environment comprises a gas flow through the 3D printer and / or collection filter to prevent oxidation reactions.

[0035] Metal powder passivation can occur at the location where waste powder is generated within each printing unit, or the waste metal powder can be transferred in batches or continuously to a central processing location. Continuous transfer can be achieved using an inert gas stream carrying suspended metal powder. For example, the inert gas can be argon or nitrogen.

[0036] One advantage of passivating waste metal through melting and solidification is the significant cost savings compared to alternative batch transfer methods. Another advantage is that passivating waste powder at the printing site allows for the possibility of recycling the waste powder. The solid metal blocks collected during passivation can be processed into standard-sized ingots, much larger than the particle size of the waste powder. These ingots can be reused as raw materials for future 3D printing or for other industries that use metal ingots as raw materials.

[0037] In this disclosure, waste powder or waste metal powder refers to, but is not limited to, powder generated during the printing process and referred to as “condensate.” For example, when a laser beam in an LPBF system heats metal powder, some of the metal may evaporate and be carried away by a gas flow. This evaporated metal is also referred to as condensate. These condensates are expected to be the most reactive portion of the waste powder and can be collected from cyclone separators and filters associated with the 3D printing equipment. Alternatively or additionally, waste powder or waste metal powder may include powder remaining after printing (e.g., in the printing bed). Compared to condensate, this waste powder may have a larger particle size and lower reactivity. For example, the size of waste powder particles can range from 1 micrometer to 400 micrometers.

[0038] In one or more embodiments, the apparatus and methods contemplated herein may include one or more 3D printers, each producing separate waste metal powder, which is collected in an inert gas environment and provided to a passivator. The waste metal powder is dried by the inert gas and remains unreactive before being collected and removed from the 3D printing system or redistributed to the 3D printer for further printing.

[0039] The filtering and / or passivation apparatuses and methods disclosed herein are not intended to be limited to the specific embodiments described herein. These apparatuses and methods may be implemented independently or in combination with each other.

[0040] In one aspect of this disclosure, the passivation technique described herein involves collecting waste metal powder (e.g., condensate) trapped in an inert gas stream and melting the waste metal powder via a passivator. The passivator disclosed herein is a structure capable of receiving waste powder from a 3D printing process and melting the waste powder for a container to receive the molten waste powder (e.g., melting and cooling the waste powder into a solid ingot). In one or more embodiments, the apparatus of this invention is configured to receive an inert gas stream passing through a 3D printer, a passivator, and a container for collecting the waste powder. In one or more embodiments, the apparatus of this invention includes a filter element that separates the waste powder from the inert gas stream and collects the waste powder in the filter element or container, where the powder can be passivated by heating the powder until the powder particles agglomerate to a size unlikely to undergo oxidation. For example, the filter element may be a cyclone separator or a filter screen.

[0041] In one or more embodiments, the passivator and / or collection container may be a container for storing waste powder generated during printing, which is coupled to the 3D printer and maintained under an inert atmosphere (such as argon or nitrogen). It is conceivable that the passivator may be equipped with a dedicated jacket or heating element, thereby allowing the temperature of the passivator or the temperature of its components to be adjusted to melt the waste powder collected therein. In one or more embodiments, the passivator may have heating and cooling capabilities along a desired section of its height, the passivator being configured to heat and cool the desired section.

[0042] Once the first portion of the waste powder is collected in a passivator (which can essentially be disposable), a heating process is initiated to melt the waste powder. The heating process can be designed to be interactive, with the passivator heated only in sections containing newly deposited metal powder. This procedure allows the molten waste powder to melt and coalesce into one or more pools of molten metal, which can then be cooled to ambient temperature for solidification using a cooling mechanism. The top layer of cooled metal can then be heated together with newly deposited powder to repeat the process.

[0043] In one or more embodiments, the passivator includes an insulating material. Such insulating materials can help separate the heating and cooling zones within the passivator and / or the container of molten waste powder. These materials can be powder-based (e.g., sand) or refractory chemicals. These materials can be added in batches to the waste metal powder to create an insulating layer for the waste powder. The purpose of this addition is to isolate the already molten and cooled bulk waste metal from the layer of waste powder to be melted.

[0044] In one or more embodiments, the collected waste powder can be heated in small portions, thus reducing the need to collect larger volumes of bulk metal after melting and solidification. The smaller volume makes removal from the collection point in the 3D printer easier to automate and eliminates the potential need for heated / cooled zones on the same collection container. Such a process can be performed by collecting the powder in a smaller tray, heating to melt, cooling to solidify, and automatically moving the small tray to a central location in an inert environment. Finally, the solid collection can be removed from the inert container. The collected solid metal can be used as feedstock to prepare new metal powder for use in future 3D printing processes. Molten metal can be collected in large quantities or used to fill molds with desired shapes. The molten metal can be analyzed and mixed with specific elements for use in high-end metal markets such as powder metallurgy or 3D printing.

[0045] In one or more embodiments, the passivator and / or collection container has the ability to determine and notify the printer / operator of the powder / bulk metal fill level. In one or more embodiments, the passivator and / or collection container may determine, for example, via acoustic wave penetration, whether the powder has solidified into a bulk form.

[0046] In another aspect of this disclosure, the passivation process is performed continuously during the 3D printing process. During continuous passivation, the generated waste powder is directly conveyed to a passivator, which is or has a crucible, furnace, or other heatable container, in which the waste powder is melted and transformed into molten metal. The passivator can heat the waste powder by various methods (such as induction heating), although the heating method must be sufficient to ensure that the temperature of the waste powder reaches its melting point. For example, the passivator is capable of heating the waste powder to over 660 degrees Celsius (the melting point of aluminum). Alternatively, the heating process can be performed simultaneously during the gaseous transfer of the waste powder to the passivator, or in a container at the 3D printer, or as disclosed elsewhere herein. For example, a container connected to the 3D printer for storing the waste powder generated during printing can be maintained in an inert atmosphere and equipped with a dedicated jacket or heating element, such that the temperature of the container or a portion thereof can be regulated to melt the waste powder released therein. In one or more embodiments, the molten metal is not allowed to cool to solidify in the passivator, but instead flows out of the container for further processing.

[0047] Waste powder can be conveyed directly or via an inert gas flow mixed with waste powder particles to a passivator. In continuous passivation methods involving inert gas flow, the process is synchronized with the flow of waste powder into and out of the 3D printer. In one or more embodiments, the passivator may include a filter element that collects waste powder passing through a crucible. For example, the filter element may be a mesh. In one or more embodiments, the filter element is a heated, high-temperature mesh capable of withstanding temperatures sufficient to melt the waste metal powder. For example, the filter element may be an aluminosilicate filter element. In one or more embodiments, the surface of the passivator is heated to perform additional waste powder melting. Furthermore, the filter element has sufficient size, thickness, and shape to ensure that the waste powder particles in the gas flow are completely converted into a molten form. The pressure of the gas flow should be sufficient to blow the molten metal against the surrounding hot walls of the passivator, which will guide the melt to a collection container. This process can be combined with other actions that increase the powder melting rate, increase the molten metal collection rate, or assist the inert gas flow, such as rapid vibration of the filter element and the passivator as a whole, or centrifugal rotation of the passivator. Suspended waste metal particles are removed from the inert gas by passing it through a passivator, and the inert gas can then be guided back to the 3D printer.

[0048] In one or more embodiments, the filter element is made of a material with a melting point lower than that of the passivator. For example, the filter element may be composed of a material with a melting point equal to or close to that of the waste powder. For example, in a printing system using aluminum powder, the filter element may be aluminum. In this way, the filter element is fusible during the heating operation of the passivator. In one or more embodiments, the filter element is suspended above the crucible, where it collects waste powder from an inert gas flow. In one or more embodiments, the filter element may be pressure-sensitive. For example, upon reaching a certain back pressure, the filter element will undergo a rapid recirculation of inert gas to dislodge the trapped waste metal particles and allow them to fall into the crucible. Once the recirculation procedure is complete, the filter element continues its standard operation. Replacing the filter element at regular intervals can be advantageous in itself. This process can be initiated by dropping the filter element into the crucible. Filter element replacement can be arranged to automatically replace the dropped filter element without opening the housing and interrupting the printing program. The advantage of this arrangement is that ordinary filter element units can be used without the need for high-temperature materials. Once the filter element is melted into the molten pool, the filter element material can be selected to control the overall composition of the molten alloy.

[0049] In embodiments where the filter element of the passivator is located in a heated container (e.g., an oven, crucible, furnace), the seals maintaining the inert gas environment must function at the elevated temperature. After cooling, the filter element can be opened or treated with water (or an aqueous sodium hydroxide solution) before opening.

[0050] In cases where the waste powder contains very small particles, after the inert gas flow containing the waste powder condenses through a filter element to remove the coarser particles, the gas flow can be directed to a washing section. This section will cause the waste powder carrying the inert gas flow to pass through water or an aqueous solution of sodium hydroxide, and then to a gas drying section (e.g., a dehumidifying dryer) to allow for the reuse of the inert gas. Care must be taken to ensure the safe collection or venting of synthetic hydrogen.

[0051] In one or more embodiments, the passivator may include an electrostatic element capable of generating an electromagnetic field arranged to attract waste metal powder particles from an inert gas flow. In this way, waste powder can be filtered from the inert gas flow. For example, the electrostatic element may be one or more charged metal plates, grids, rods, cups, etc. In one or more embodiments, the electrostatic element may be heated to melt the collected waste powder.

[0052] In one or more embodiments, the passivator may include a centrifugal filter unit and a crucible. For example, the centrifugal filter unit of the passivator may be made of a high-temperature filter material and is designed in a cylindrical shape. As an inert gas stream flows from the outside of the filter element to the inside of the centrifugal filter unit, the filter material allows waste powder to be filtered out of the inert gas stream. In one or more embodiments, the inert gas stream containing waste powder may flow through an inlet port or inlet in the centrifugal filter unit. In one or more embodiments, the inert gas stream containing waste powder may flow through filter material constituting the outer surface of the centrifugal filter unit (e.g., on a capture wall). The centrifugal filter unit is configured to rotate about a longitudinal central axis during operation, which further pushes the waste powder (which is heavier than the inert gas) against the filter material located on the outside of the unit. In one or more embodiments, the centrifugal filter unit includes an outlet port or outlet for returning the filtered inert gas to a printing machine or transferring it for further processing. The outlet port or outlet may be coupled to a tubular shaft extending into the interior of the centrifugal filter unit. In one or more embodiments, the passivator includes a crucible surrounding a centrifugal unit capable of heating the waste powder to its melting point. The crucible acts as a jacket, allowing it to be heated to the melting temperature of the waste powder. In one or more embodiments, the melting point of the centrifugal filter unit is higher than the melting point of the waste powder. In one or more embodiments, the melting point of the centrifugal filter unit is lower than the temperature the crucible can reach to heat the centrifugal filter unit. In this way, the centrifugal unit can be melted together with the waste powder. The crucible may also include an exit port or outlet for allowing the molten waste powder to flow out of the passivator. This outlet may be a tubular structure located at the bottom of the passivator, where gravity causes the molten waste powder to flow toward and through the outlet. In one or more embodiments, the outlet is coupled to or leads to a collection container for the melted waste powder.

[0053] The passivator may consist of one or more elements disclosed herein. For example, the passivator may further include electrostatic elements combined with a centrifugal filter unit and / or crucible, as disclosed elsewhere herein. Filter element regeneration can be optimized using the rotational speed, temperature, and gas flow of the centrifugal unit (which may be designed to allow intermittent reverse flow). The passivator can be used continuously by maintaining a high temperature or in batches, wherein the unit is placed offline for regeneration. In the case of offline filter element placement, a replacement device will be automatically connected to ensure that the process continues with minimal interruption.

[0054] refer to Figure 1 A device 100 for passivating waste powder is provided. The device includes one or more 3D printers 105 capable of additive manufacturing structures using a laser-based technique based on metal powder. During or after 3D printing, a pump 110 provides a flow of inert gas to the printing area to capture waste powder and form a “dirty gas” of inert gas and waste powder (e.g., condensate). For example, the inert gas may be argon or nitrogen. The gas flow is directed through inlet 120 to a passivator 115. Inlet 120 may be, for example, a pipe coupled to or in airflow communication with the inert gas flow pumped to the 3D printer 105. The passivator 115 is configured to receive the gas flow and separate and passivate the waste powder from the gas flow to limit or minimize the probability of a large oxidation reaction occurring when the waste powder is exposed to air or moisture.

[0055] The passivator 115 may include one or more components for performing passivation, including a filter element 125, a heating element 130, a rotation mechanism 135, and / or an electrostatic element 140.

[0056] Filter element 125 receives and filters waste powder from a gas flow. In one or more embodiments, filter element 125 forms part of the surface of a passivator. In one or more embodiments, filter element 125 is a cyclone filter, a filter screen, a thermally conductive woven metal mesh, or a centrifugal filter unit. In one or more embodiments, filter element 125 is housed within passivator 115 or within other elements of the passivator, such as heating element 130. Heating element 130 can be any element capable of heating the passivator to raise the temperature within the passivator sufficient to melt the waste powder housed in the filter element. For example, heating element 130 can be an induction heater, crucible, furnace, heating jacket, coil housed within or adjacent to the housing surface of filter element 125, as described elsewhere herein. As the waste powder melts, it coalesces and flows into a collection tank that guides the metal to a collection container (e.g., container 150). This process can be combined with rapid vibration of filter element 125 to enhance the separation of liquefied metal. It should be understood that the process is carried out in an inert atmosphere, in which a gas such as argon or nitrogen is maintained.

[0057] In various embodiments, the rotating mechanism 135 may be coupled to or form part of the filter element 125. In this way, the rotating mechanism 135 can provide rotational motion to the filter element, and the resulting centrifugal force can be used to separate waste powder from the inert gas flow.

[0058] The electrostatic element 140 may include one or more charged plates, grids, rods, cups, etc., for generating an electromagnetic field in the passivator 115. Since waste powders such as aluminum are generally attracted by electric charge, these electromagnetic fields can be configured to attract waste powder particles from the gas flow and adsorb the waste powder particles onto the filter element 125 or other suitable locations.

[0059] As waste powder is collected in passivator 115, heating element 130 raises the temperature of the waste powder to its melting point. For example, the melting point of aluminum is approximately 660 degrees Celsius. As the waste powder melts, it forms molten waste powder. This molten waste powder is directed to outlet 145, which may be a tube, a tapered section, or other outlet known in the art, at which the molten waste powder leaves the passivator and reaches container 150. Container 150 is a collection container designed to safely collect the molten waste powder, where it can coalesce and cool with little or no risk of oxidation. The collected waste powder can then be processed continuously or in batches to remove it from the 3D printing environment or to recycle it for future printing applications.

[0060] In one or more embodiments, the passivator 115 further includes a gas outlet 155. The gas outlet 155 may be a tube, a tapered section, or other similar structure that allows inert gas to exit the passivator 115 once waste powder has been filtered from the gas flow. In this way, the gas flow can be "cleaned." The gas flow can then be conveyed to a dehumidifying dryer 160, which dries the gas flow and removes any moisture entrained in it. Once the gas flow is dried, it can be pumped back to the 3D printer 105 to pick up any additional waste powder generated at the 3D printing powder bed.

[0061] refer to Figure 2 A passivator 200 is provided. As disclosed herein, the passivator 200 can receive an inert gas containing waste powder particles (such as condensate), which is heated to melt the particles for collection and removal from the 3D printing environment. In one or more embodiments, the waste powder is fed directly to a heating element 230 (such as a crucible). The heating element 230 can be heated by induction, heating coils, lasers, flames, or other heating solutions known to those skilled in the art. In one embodiment, the heating element 230 includes a conical design in which the waste powder is fed to the heating element through a wide-opening nozzle 235, heated within the body of the heating element, and conveyed as molten waste powder to a narrower outlet 245, which can be a tube, a conical section, or other outlets known in the art. After the molten waste powder flows out of outlet 245, it can be collected in a container 250 for processing.

[0062] The passivator 200 may optionally include a filter element 225, as disclosed elsewhere herein, which can receive an inert gas containing waste powder particles. In one or more embodiments, the filter element 225 is made of the same material as the waste powder, or of a material with a melting point equal to or close to that of the waste powder. For example, in a printing system using aluminum powder, the filter element 225 may be made of aluminum. Thus, once the filter element 225 receives the waste powder, it can fall into the heating element 230, and the combination of the filter element and the waste powder can be melted into molten waste and conveyed to the container 250 through the outlet 245.

[0063] refer to Figure 3A passivator 300 is provided. As disclosed herein, the passivator 300 can receive an inert gas containing waste powder particles (such as condensate), which is heated to melt the particles, thereby collecting and removing them continuously from the 3D printing environment. The passivator 300 includes a filter element 325 and a heating element 330. The filter element 325 can be, for example, a filter screen. In one or more embodiments, the filter element 325 is made of a material with a melting point higher than that of the waste powder to ensure that the filter element remains solid during the melting of the waste powder. The heating element 330 can be a crucible, a furnace, or other gas-impermeable, heatable container. As the filter element 325 collects waste powder from the inert gas, the heating element 330 increases in temperature to melt the waste powder. The molten waste powder exits the heating element 330 through an outlet and is collected in a container, as disclosed elsewhere herein. Figure 3 As shown, inert gas is supplied to passivator 300 via the flow indicated by reference numeral A (indicating "dirty" gas flow into filter element 325) and reference numeral B (indicating "clean" gas flow (without waste powder) leaving heating element 330).

[0064] refer to Figure 4A and Figure 4B A passivator 400 is provided. As disclosed herein, the passivator 400 can receive an inert gas containing waste powder particles (such as condensate), which is heated to melt the particles for collection and removal from the 3D printing environment, and the passivator can also provide rotational motion to generate centrifugal force, thereby further separating the inert gas from the waste powder. The passivator 400 includes a highly heat-resistant cylindrical filter element 425. The filter element 425 includes a central longitudinal shaft 450 configured to provide rotational motion to the filter element. The shaft 450 can be powered by a motor or other conventional device. The inert gas containing waste powder enters the filter element 425 through an inlet 455, which can be a tube, a tapered section, or other opening.

[0065] A heating element 430 surrounds the filter element 425. The heating element 430 may be a crucible, furnace, heating jacket, or other mechanism for providing high temperatures to an area surrounding the outer surface of the filter element 425. In one or more embodiments, the filter element 425 is made of a material with a melting point exceeding that of the waste powder.

[0066] Once the inert gas carrying the waste powder enters the filter element 425, the rotational motion provided by the shaft 450 is used to push the larger waste powder particles toward the side of the filter element, closer to the heating element 430. The high temperature provided by the heating element 430 is used to melt the waste powder into molten waste powder. This molten waste powder is collected near the bottom of the heating element 430 at or near the outlet 445. The outlet 445 can be coupled to the filter element 425. As the molten waste powder is collected, it leaves the passivator 400 through the outlet 445, where it can be collected in a container or other receiver, as disclosed elsewhere herein. Additionally, the rotational motion and the removal of the waste powder mass from the inert gas lighten the inert gas, causing it to rise and exit the filter element through the filtered gas outlet 460. This gas outlet 460 can be placed in series with other components, such as a dehumidifier and / or a 3-D printer, to allow for inert gas circulation.

[0067] Figure 5A and Figure 5B This is a flowchart of an example method 500 for waste powder passivation according to the disclosure herein. Method 500 begins: waste powder is generated by a 3D printer during the 3D printing of a part, 505. The waste powder may be a metal, such as aluminum. The waste powder may be collected in a powder bed or a container at the 3D printer. The waste powder may be suspended in a gas flow, such as condensate carried away from the powder bed by a gas flow of inert gas.

[0068] In one or more embodiments, method 500 may optionally continue by circulating an inert gas to the 3D printer to generate a gas flow carrying waste powder, 510. For example, the inert gas may be argon or nitrogen. The gas flow carrying waste powder is then conveyed to a passivator, 515. The passivator may be any passivator disclosed herein (e.g., passivator 115, 200, 300, 400) or any combination of elements from these passivator embodiments.

[0069] When a gas flow carrying waste powder is fed to a passivator, method 500 can manipulate the gas flow to separate the waste powder from the gas. This can be achieved in various ways, individually, or in combination with one or more options. In one or more embodiments, method 500 applies an electrostatic charge to the gas flow to attract the waste powder to the passivator, wherein the passivator includes an electrostatically charged portion, 520. In one or more embodiments, method 500 causes the passivator to rotate centrifugally to separate the waste powder from the gas flow, 525. In one or more embodiments, method 500 feeds the gas flow to a cyclone separator and / or filter cartridge to remove coarse waste powder particles and / or filter out waste powder particles, 530. In one or more embodiments, method 500 recirculates the gas flow to a dehumidifying dryer, 535. In one or more embodiments, method 500 recirculates the gas flow to a 3D printer, 540. Thereafter, once the waste powder has been separated from the gas flow, it is collected in the passivator, 545.

[0070] Method 500 continues: the passivator is heated to melt the waste powder, 550. This produces molten waste powder. In one or more embodiments, the passivator is heated to the melting point of the waste powder, but not to the melting point of the passivator or any of its components. In one or more embodiments, the passivator is melted, 555. Thereafter, method 500 collects the molten waste powder, 560. The molten waste powder can be collected in various components, including filter cartridges, crucibles, containers, or other receivers as disclosed elsewhere herein.

[0071] In other embodiments, only a portion of the passivator is melted. Therefore, the method may optionally or additionally continue by melting the filter element together with the collected waste powder, 565. For example, the filter element in the passivator may be made of a material with a melting point that will cause the filter element to melt together with the waste powder when it is formed.

[0072] The method may also optionally or additionally collect the molten waste powder through the outlet of the passivator, 570. The outlet may be located at the bottom of the passivator, and gravity may guide the molten waste powder through the outlet to a collection container, as disclosed herein.

[0073] refer to Figure 6 This document provides a method 600 for passivating waste powder according to the disclosure herein. Method 600 begins with waste powder generated by a 3D printer during the 3D printing of a part, 605. The waste powder may be a metal, such as aluminum. The waste powder may be collected in a powder bed or a container at the 3D printer.

[0074] In one or more embodiments, method 600 may optionally continue by circulating an inert gas to the 3D printer to generate a gas flow carrying waste powder (e.g., condensate), 610. For example, the inert gas may be argon or nitrogen. The gas flow carrying waste powder is then conveyed to a passivator, 615. The passivator may be any passivator disclosed herein (e.g., passivator 115, 200, 300, 400) or any combination of elements from these passivator embodiments. In one or more embodiments, method 600 provides the waste powder to the passivator via a physical conveyor or in combination with the gas flow. In one or more embodiments, the passivator comprises an aqueous solution.

[0075] Once the waste powder is supplied to the passivator, the passivator works to wash the waste powder in any container, filter, separator, or other component with an aqueous solution. For example, the aqueous solution can be water alone, or an aqueous solution containing alkali or salt. Advantageously, method 600 ensures that the waste powder is processed (or synchronized online with the 3D printer) while it is being produced by the 3D printer, rather than being collected in bulk before being transferred to a storage and processing area.

[0076] Method 600 continues: agitating the gas flow carrying waste powder to produce a waste powder slurry, 620. Agitation of the gas flow carrying waste powder can be achieved in a variety of different ways. For example, a passivator can pass the waste powder through a fine mist of aqueous solution, or alternatively through a curtain of aqueous solution, or alternatively through bubbling, or alternatively by a mixing mechanism (such as a fan, blender, mixer, or propeller) to mix the waste powder with the aqueous solution. In one or more embodiments implementing the mixing mechanism, the agitation provided by the mixing mechanism can generate heat, which is used to dissipate the escaping gas. The temperature of the aqueous solution and the concentration of alkali or salt (if used) are adjusted for optimal treatment and processing of the waste powder. In the case of treating the waste powder with an aqueous solution to generate hydrogen, the hydrogen is collected or discharged according to methods known and described in the literature.

[0077] Method 600 also collects the waste powder slurry through the outlet of the passivator, 625. The outlet may be located at the bottom of the passivator, and gravity may guide the waste powder slurry through the outlet into a collection container, as disclosed herein.

[0078] refer to Figure 7This document provides a method 700 for passivating waste powder according to the disclosure herein. Method 700 begins with waste powder generated during 3D printing of a part by a 3D printer, 705. The waste powder may be metal, such as aluminum. The waste powder may be collected in a powder bed or a container at the 3D printer. When collecting waste metal powder, there are potential hazardous situations when collecting it in batches. Therefore, separating the powder to allow for more controlled oxidation and a lower probability of runaway reactions is advantageous.

[0079] In one or more embodiments, method 700 may optionally continue by circulating an inert gas to the 3D printer to generate a gas flow carrying waste powder, 710. For example, the inert gas may be argon or nitrogen. The gas flow carrying waste powder is then conveyed to a passivator, 715. The passivator may be any passivator disclosed herein (e.g., passivator 115, 200, 300, 400) or any combination of elements from these passivator embodiments. In one or more embodiments, method 700 provides the waste powder to the passivator via a physical conveyor or in combination with the gas flow.

[0080] Method 700 continues: the waste powder is mixed with an encapsulating agent or reactant to solidify the waste powder, 720. The encapsulating agent or reactant may be a reactive material that solidifies via reaction, or a hot melt that solidifies upon cooling, or a combination thereof. In one or more embodiments, the waste powder is mixed with the encapsulating agent or reactant by a mixing mechanism (e.g., a fan, a mixer, a blender, or a propeller). The powder and the encapsulating agent or reactant are fed into the mixing mechanism to be mixed continuously and extruded continuously in a shape and size determined to be optimal for the safety and storage of the encapsulated powder. In one or more embodiments implementing the mixing mechanism, the agitation provided by the mixing mechanism may generate heat that is used to dissipate escaping gases. The encapsulating agent or reactant may be formulated to have desired moisture or oxygen permeability, or may consist of flame-retardant or fire-extinguishing materials. Alternatively, the mixing mechanism may include: (1) an additive, such as Butvar B-90; and (2) a solvent (e.g., isopropyl, acetone) to passivate and solidify the pure waste metal particles.

[0081] Method 700 also collects the waste powder slurry through the outlet of the passivator, 725. The outlet may be located at the bottom of the passivator, and gravity may guide the waste powder slurry through the outlet into a collection container, as disclosed herein.

[0082] As used herein, the terms “waste metal powder,” “waste powder,” “metal powder,” and similar terms include all waste metal (including waste condensate) generated during the 3D printing process, unless otherwise stated. However, this disclosure is not limited to waste metal powder generated only in the additive manufacturing industry, but includes all industries that may generate metal dust and particles.

[0083] The foregoing description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to the exemplary embodiments presented throughout this disclosure will be apparent to those skilled in the art, and the concepts disclosed herein can be applied to other support structures and systems, as well as methods, for removing support structures. Therefore, the claims are not intended to be limited to the exemplary embodiments presented throughout this disclosure, but are given the full scope consistent with the language of the claims. All structural and functional equivalents of the elements of the exemplary embodiments described throughout this disclosure (which are known or will be known hereafter by a person of ordinary skill in the art) are intended to be covered by the claims. Furthermore, nothing disclosed herein is intended to be offered to the public, whether or not such disclosure is expressly stated in the claims. Unless a claim element is expressly stated using the phrase “means for…”, or, in the case of a method claim, using the phrase “steps for…”, no claim element should be construed in accordance with 35 USC §112(f) or similar law within the applicable jurisdiction.

Claims

1. An apparatus comprising: A three-dimensional (3-D) printer, wherein the 3-D printer generates waste powder during the 3-D printing of printed parts; A passivator, configured to receive the waste powder and melt it; and A container configured to collect molten waste powder.

2. The apparatus of claim 1, further comprising a pump configured to circulate an inert gas through the apparatus to generate a gas flow carrying the waste powder.

3. The apparatus of claim 2, wherein, The gas flow is continuous.

4. The apparatus of claim 2, wherein, The passivator receives a gas flow carrying the waste powder.

5. The device according to claim 1, further comprising a filter element.

6. The device according to claim 5, wherein, The filter element is heated.

7. The device according to claim 5, wherein, The passivator is configured to receive the filter element and melt it.

8. The device according to claim 1, further comprising a rotation mechanism for rotating the passivator.

9. The device according to claim 1, wherein, The passivator is induction heated.

10. The device according to claim 1, wherein, The passivator includes an electrostatically charged portion.

11. The device according to claim 1, wherein, The passivator includes an outlet.

12. The apparatus of claim 1, further comprising a cyclone separator.

13. The apparatus according to claim 1, further comprising a dehumidifying dryer.

14. A method for passivating waste powder, comprising: Waste powder is generated by 3D printers during the 3D printing of parts; The waste powder is collected in a passivator; Heating the passivator to melt the waste powder; and Collect the molten waste powder. The passivator maintains an inert environment.

15. The method of claim 14, further comprising circulating an inert gas to the 3D printer to generate a gas flow carrying the waste powder; and The gas flow carrying the waste powder is conveyed to the passivator.

16. The method of claim 15, further comprising applying an electrostatic charge to the gas flow to attract the waste powder to the passivator, wherein, The passivator includes an electrostatically charged portion.

17. The method of claim 15, further comprising centrifugally rotating the passivator to separate the waste powder from the gas flow.

18. The method of claim 15, further comprising conveying the gas flow to a cyclone separator to remove coarse waste powder particles.

19. The method of claim 15, further comprising circulating the gas flow to a dehumidifying dryer.

20. The method of claim 15, further comprising recirculating the gas flow to the 3D printer.

21. The method according to claim 14, wherein, The passivator includes a filter element for collecting the waste powder.

22. The method of claim 21, further comprising melting the filter element together with the collected waste powder.

23. The method of claim 14, further comprising melting the passivator.

24. The method of claim 14, wherein, The molten waste powder is collected through the outlet of the passivator.

25. The method according to claim 14, wherein, The inert environment is argon or nitrogen.

26. A method for passivating waste powder, comprising: Waste powder is generated by 3D printers during the 3D printing of parts; An inert gas is circulated to the 3D printer to generate a gas flow carrying the waste powder; The gas flow carrying the waste powder is conveyed to the passivator; Agitate the gas flow carrying the waste powder to generate a waste powder slurry; and The waste powder slurry is collected from the outlet of the passivator. The passivator contains an aqueous solution.

27. A method for passivating waste powder, comprising: Waste powder is generated by 3D printers during the 3D printing of parts; An inert gas is circulated to the 3D printer to generate a gas flow carrying the waste powder; The gas flow carrying the waste powder is conveyed to the passivator; The waste powder is mixed with a reactant to solidify the waste powder; and The inert gas is collected from the outlet of the passivator.

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