Systems and methods for recycling lead pieces

Abstract

A system for melting lead scrap pieces includes a vessel. A vortex chamber is disposed within the vessel. The vortex chamber includes an inlet, an outlet, and an open top configured to receive the lead pieces. A pump is disposed within the vessel and directs molten lead to the inlet of the vortex chamber. A dross dam divides the vessel into a first region and a second region. The vortex chamber is disposed in the second region, and a conduit extends between the vortex chamber outlet and the first region. A transfer pump is disposed in the second region and configured to remove molten lead from the vessel. The system allows dross to be removed from the surface of the molten lead bath in the first region.

Description

[Technical field]

[0001] This application claims the benefit of U.S. Provisional Application No. 62 / 945,736, filed December 9, 2019, which is incorporated herein by reference.

[0002] <Background> The Background Discussion contains information believed to be useful in understanding the present invention. No admission is made that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

[0003] The present exemplary embodiments relate to methods and systems for recycling lead. The present exemplary embodiments find particular application in connection with melting the lead component of acid lead-acid batteries and achieving separation from other battery components and will be described with particular reference thereto. However, it will be understood that the present exemplary embodiments are also applicable to other similar applications.

[0004] Lead-acid batteries (LAB) are the largest type of battery in use today. They are essential for a variety of applications, including starting automobile engines, providing emergency backup power for data centers, and powering industrial and recreational vehicles such as forklift trucks and golf carts. Unlike other batteries, LAB are nearly 100% recycled. This feature has established lead as a major recycled commodity. Global production of LAB is increasing year by year, but as lead-rich deposits are depleted, it is becoming more difficult to produce new lead from the ore. Not surprisingly, new and more efficient methods for lead recycling are urgently needed.

[0005] Recovery of lead from used batteries is of great economic importance, both as a source of raw materials and in terms of hazardous waste disposal problems. For many years, battery recycling plants have disassembled batteries, removed the acid, and crushed the remaining materials into smaller pieces. Crushing and grinding separated most of the paste from the grids and crushed the plastic parts of the battery. In a series of hydrometallurgical processes, the paste was separated into the metallic lead and plastic parts of the battery. Most of the chloride-containing plastics, along with other non-recycled plastic, glass, and inorganic components of the battery, were separated from the paste and metals.

[0006] The standard method of recovering lead from spent batteries involves melting the lead-bearing parts of the batteries in a reverberatory, rotary, blast or electric furnace using standard pyrometallurgical techniques. Typically, the cells are cut into small pieces and heated until the metal liquefies. Burning the non-metallic material leaves a black slag on its surface, which is removed with a slug arm.

[0007] It should also be noted that lead scrap material is obtained during the manufacture of various lead-containing products. For example, in the manufacture of lead-acid batteries, lead is formed into solid sheets from which components are cut or punched. This process produces sheet remnants. Such remnants are referred to herein as run-around scrap. This run-around scrap is typically on-chemistry (i.e., the alloy composition of the scrap pieces matches that of the bath) and can therefore be efficiently used as fill material for a bath of molten lead.

[0008] The flat cost to reuse one tonne of batteries is between $1,000 and $2,000. European entities aim to achieve a cost of $300 per tonne. Ideally, this would include transportation costs, but the movement and handling of goods is expected to double the overall cost. To facilitate transportation, European entities have set up small processing plants in favorable geographic locations. This is partly due to the Basel Convention, which bans the export of used lead-acid batteries altogether. As the volume of discarded batteries increases, new technologies are being developed to make recycling economically viable without institutional or government support.

[0009] The present disclosure provides an improved system and method for processing shredded lead pieces and improves the efficiency of the smelting process to produce clean molten lead. Additionally, the reclamation smelting process can be used to melt on-chemistry runaround scrap. Summary of the Invention

[0010] Various details of the present disclosure are summarized below to provide a basic understanding. This summary is not an extensive overview of the disclosure, and is not intended to identify particular elements of the disclosure or to delineate the scope thereof. Rather, the primary purpose of this summary is to present some concepts of the disclosure in a simplified form before the more detailed description that is presented below.

[0011] According to one exemplary embodiment, a system for recycling lead scrap is provided. The system includes a vessel defining a vortexing chamber. The vortex chamber includes an inlet, an outlet, and an open top configured to receive the lead pieces. A pump is disposed within the vessel and directs molten lead to the inlet of the vortex chamber. A dross dam divides the vessel into a first region and a second region. The vortex chamber is disposed in the second region, and a conduit extends between the outlet of the vortex chamber and the first region. A transfer pump is disposed in the second region and configured to remove the molten lead from the vessel.

[0012] According to another embodiment, a system for recycling lead pieces is provided. The system includes a vessel configured to contain a bath of molten lead. The vessel is divided into a whirlpool chamber, a dross chamber, and a main bath region. The whirlpool chamber has an inlet, an outlet, and an open top configured to receive the lead pieces. A first pump is disposed in the main bath region, the first pump positioned to supply molten lead to the inlet of the whirlpool chamber. A dross dam separates the dross chamber from the main bath region. A conduit extends between the outlet of the whirlpool chamber and the dross chamber. A second pump is disposed in the main bath region to remove the molten lead from the vessel.

[0013] According to a further embodiment, a method for recycling lead is provided. The method includes providing a vessel including a bath region, a vortexing region, and a dross removal region. Molten lead is introduced into the vessel. A flow of molten lead is introduced into the vortexing region. Solid lead pieces are introduced into the molten lead in the vortexing region. A portion of the molten lead is directed from the vortexing region to the dross removal region to remove floating dross. Clean molten lead flows from the dross removal region to the bath region and from the bath region to downstream processing. [Brief description of the drawings]

[0014] Below is a brief description of the drawings, which are presented for the purpose of illustrating, but not limiting, the exemplary embodiments disclosed herein. [Figure 1] FIG. 1 is a plan view of the lead scrap recycling chamber. [Diagram 2] FIG. 2 is a top view of the lead scrap recycling chamber of FIG. 1 with the lid engaged. [Diagram 3] FIG. 3 is a perspective view, partially in phantom, of the lead scrap recycling chamber. [Figure 4] FIG. 4 is a perspective view of the vortex chamber of the scrap recycle chamber. [Diagram 5] FIG. 5 is a side view of the dispersion plate of the exhaust conduit.

[0015] <Detailed Description> A more complete understanding of the components, methods and devices disclosed herein can be obtained by reference to the accompanying drawings, which are merely schematic representations for convenience to easily illustrate the present disclosure, and thus are not intended to indicate the relative sizes and dimensions of the devices or their components, and / or to define or limit the scope of the example embodiments.

[0016] In the following description, specific terms are used for clarity, but these terms are intended to refer only to the specific structures of the embodiments selected for illustration in the drawings, and are not intended to define or limit the scope of the disclosure. In the drawings and the following description, like numerical designations should be understood to refer to components having similar functions.

[0017] The singular forms "a," "an," and "the" include plural referents unless the context clearly indicates otherwise.

[0018] As used herein, the terms "about," "generally," and "substantially" are intended to encompass structural or numerical modifications that do not significantly affect the purpose of the element or value modified by the term.

[0019] As used in the specification and claims, the term "comprising" may include the embodiments "consisting of" and "consisting essentially of." As used herein, the terms "comprise(s)," "include(s)," "having," "has," "can," "contain(s)," and variations thereof are intended to be open-ended transitional phrases, terms, or words that require the presence of the specified components / steps and allow for the presence of other components / steps. However, such descriptions should be construed as describing the compositions or methods as "consisting of" and "consisting essentially of" the recited components / steps, which allows that only the recited components / steps may be present along with impurities that may result therefrom, and that other components / steps are excluded.

[0020] The present disclosure relates to a system suitable for recycling lead scrap material of the type obtained from lead-acid batteries. In recycling lead-acid batteries, the lead is separated from the plastics, acids and other materials that form the finished battery by crushing, fine cutting and separation. However, some contamination or contamination of the lead component is unavoidable. Therefore, the lead component is typically melted to separate the contaminants from the pure lead. Most of the lead scrap pieces are thin-walled, since this is the form of lead used in typical acid lead batteries. Melting the thin-walled scrap pieces is difficult because they float on the molten metal, which greatly impedes their rapid immersion in the molten lead.

[0021] The present disclosure provides a melting apparatus that is fed with pieces of lead scrap and removes floating dross from the surface of the molten lead.

[0022] With reference to Figures 1 to 3, a cylindrical lead recycling chamber 10 is shown. The recycling chamber 10 functions as a furnace. Furthermore, the chamber 10 may be equipped with one or more electric or gas heaters 11 to allow heating of the chamber walls and melting of the lead therein. A starter volume of lead may be introduced to the furnace in solid form and melted therein or may be introduced in a molten state and maintained as a liquid.

[0023] The recycle chamber 10 is an open-top, bottomed vessel that can be constructed of any material, such as steel, that is resistant to molten lead and can withstand temperatures up to about 350°C.

[0024] The vessel may include a mechanical circulation pump 12 which directs molten lead from a bath contained within chamber 10, via conduit 13, into a scrap immersion chamber 14 where scrap chips of lead to be recycled are deposited on the surface of the melt.

[0025] The circulation pump 12 may be of the type described in U.S. Patent No. 5,470,201, the disclosure of which is incorporated herein by reference, although it should be noted that the patented circulation pump may be constructed partially or entirely of steel or other metal, since the molten lead environment is at a significantly lower temperature than the molten aluminum environment for which the pump was designed.

[0026] The scrap immersion chamber 14 may be constructed of a metal such as steel. Molten lead from the scrap immersion chamber 14 flows through a conduit 20 into a dross well 16 where impurities in the form of dross are removed from the surface.

[0027] The dross well 16 may be formed by a dross dam 18 that extends between two spaced apart points on the wall of the chamber 10. The dross dam 18 may be constructed of steel.

[0028] Typically, the cross section of the vessel that constitutes the dross well is smaller than the cross section of the vessel that constitutes the clean molten lead bath. The dross dam 18 can extend from the top of the vessel 10 to at least slightly above the vessel floor, with a space between the vessel floor and the bottom edge of the dross dam 18 of 10-30% or 15-25% of the chamber height.

[0029] This space has two functions: 1) it allows the discharge conduit 20 to direct the molten lead from the scrap immersion chamber 14 to the dross well 16, and 2) it allows the "clean" molten lead, which is heavier than the dross, to sink to the floor of the vessel and flow into the main bath of molten lead.

[0030] A circulating pump 12 is positioned within the bath of molten lead within vessel 10 and forces the molten lead into scrap immersion chamber 14. More specifically, rotation of an impeller draws molten lead from the bath into the pump, through conduit 13 and into scrap immersion chamber 14.

[0031] 4, the circulating pump 12 may be mounted on a frame 21 that is an integral component with the scrap soak chamber 14. The conduit 13 may also be an integral component with the frame 21 to facilitate installation / replacement of and ensure proper alignment of the circulating pump 12. As used herein, the term "integral" means that the components are physically connected, for example, by welding.

[0032] 1-3, a ramp 24 may be provided within the scrap immersion chamber 14 such that molten metal pumped through the conduit 13 rises up the ramp, spills over an inner edge, and exits through an outlet 26 into the discharge conduit 20. The leading edge of the ramp 24 may be located adjacent to an entrance to the scrap immersion chamber 14. The entrance to the chamber may be located in a side wall or a base wall. The chamber may include an internal post 25 defining an exit 26 in the chamber base wall. The internal post may increase in height to match the increase in height of the ramp 24. In general, the interior configuration of the chamber may be described as having a bottom or low side wall entrance and a bottom exit with the ramp formed between the internal post and the side wall. The ramp may extend from 0 to 180°, or 270°, or 360° of the chamber circumference.

[0033] The outlet 28 of the discharge conduit 20 may include a dispersion plate 29 for radially directing the flow. Additionally, the dispersion plate may be spaced from the outlet of the conduit and positioned perpendicular to the direction of the primary flow of the molten lead as it exits the discharge conduit 20. The dispersion plate helps to minimize surface turbulence caused by the flow from the discharge conduit.

[0034] Located within the primary bath of vessel 10 is a transfer pump 30. The transfer pump may be of the type described in U.S. Patent Nos. 4,940,384, 5,947,705, 9,506,346 or 10,843,258, the disclosures of which are incorporated herein by reference. The transfer pump 30 is used to remove clean molten lead from the vessel for use as is commonly done in the industry. As with the other components of the system, the transfer pump may be constructed of steel, refractory, or a combination thereof.

[0035] As will be appreciated by those skilled in the art, recycled lead chips are deposited on the surface of the melt in the scrap immersion chamber 14. A scrap feed chute 32 may be included as an element of the system to facilitate introduction of the lead scrap pieces onto the melt in the scrap immersion chamber through an opening in the lid 35. The vortex of the molten lead in the vortex chamber creates a folding flow that is efficient in drawing the lead scrap pieces below the surface of the molten lead bath, thereby accelerating melting.

[0036] The lid 35 provides safety and retains heat in the molten lead bath. The lid 35 may include a sidewall portion 37 to provide adequate clearance above the vessel 10 to accommodate the height of the pump components.

[0037] The lid 35, in combination with other system components (e.g., motor mount 39 of circulating pump 12), can function to substantially close the system to the atmosphere, at least with respect to the molten lead bath contained therein.

[0038] An opening 41 may be provided above the scrap soak chamber 14 to allow lead chips to be fed thereto. An opening 43 may be provided in the side wall 37 to allow access to the dross well 16 to allow dross to be removed from its surface.

[0039] The present exemplary embodiments have been described with reference to the preferred embodiments. Of course, other modifications and alterations will occur to others upon reading and understanding the above detailed description. It is intended that the present exemplary embodiments be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

[0040] In order to assist the Patent Office and any reader of this application and any resulting patent in interpreting the claims appended to this application, Applicant does not intend that any of the appended claims or claim elements be subject to 35 U.S.C. § 112(f) unless the words "means for" or "step for" are expressly used in a particular claim.

Claims

1. 1. A system for recycling lead pieces comprising a vessel defining a vortex chamber, the vessel comprising: the vortex chamber includes an inlet, an outlet, and an open top configured to receive a piece of lead; a circulation pump is disposed within the vessel for supplying molten lead to an inlet of the vortex chamber; a dross dam dividing the vessel into a first region and a second region; a conduit extending between an outlet of the vortex chamber and the first region; a transfer pump disposed in the second region and configured to remove molten lead from the vessel; the dross dam extends from above a surface of the molten lead bath in the vessel to above a bottom of the vessel, and a space exists between the bottom of the vessel and a lower end of the dross dam to allow molten lead to flow from the first region to the second region. system.

2. The system of claim 1 , wherein the vessel, the dross dam and the vortex chamber are constructed from steel.

3. The system of claim 1 , wherein the conduit further comprises a dispersion plate.

4. The system of claim 1 , further comprising a lid covering the vessel, the lid including an opening covering the vortex chamber and a structure for suspending the transfer pump.

5. The system of claim 1 , wherein the vortex chamber includes a frame member on which the circulation pump is mounted.

6. The system of claim 5 , wherein the frame member includes a pipe in fluid communication between an outlet of the circulation pump and an inlet of the vortex chamber.

7. The system of claim 1 , wherein the container is cylindrical.

8. The system of claim 1 , wherein the circulation pump and the vortex chamber are connected by a pipe, the pipe intersecting the vortex chamber at a tangent or an angled secant.

9. A method for recycling lead utilizing the system of claim 1, comprising: introducing molten lead into said vessel; introducing said stream of molten lead into said vortex chamber; introducing solid lead pieces into the molten lead in the vortex chamber; directing a portion of the molten lead from the vortex chamber into the first region to remove floating dross; flowing molten lead from the first area to the second area and removing the molten lead from the second area for downstream processing. method.

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