System and method for the use of impure aluminum as a renewable energy carrier

Abstract

A method of manufacturing a smelting anode. A solid aluminum hydrate and solid impurity is precipitated from an aluminate solution. The non-aluminum impurity is separated, and smelting anode is cast therefrom. A method of creating an energy carrier using impure aluminum produced by a smelting cell.

Description

SYSTEM AND METHOD FOR THE USE OF IMPURE ALUMINUM AS A RENEWABLE ENERGY CARRIERCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to, and is a non-provisional of, U.S. Patent Application 63 / 647,495 (filed May 14, 2024), the entirety of which is incorporated herein by reference.BACKGROUND OF THE INVENTION

[0002] The threat of climate change has pushed humanity to search for new ways of generating, carrying, and consuming energy without the use of greenhouse gas emitting hydrocarbon fuels. Today, there are many solutions that have been proposed for the generation of renewable energy, including wind, solar, nuclear, geothermal and other forms of generation. These solutions are typically interconnected into an electrical grid system which provides transmission and distribution of electricity to the point of energy demand. However, electrical grids are infeasible as the sole method of carrying energy due to their high fixed cost and spatially fixed nature. Today, the world energy system heavily relies on a combination of electrical grids and hydrocarbon fuels.

[0003] The use of hydrocarbon fuels provides a highly energy dense method of cost effectively carrying energy across long distances without direct transmission losses. Applications such as marine propulsion, aviation propulsion, land vehicle propulsion, as well as mobile and backup energy generation are not suitable for grid energy as the primary energy source and require energy carriers to provide the mobility and flexibility inherent to the application. Today, the dominant mode of thinking is to expand the electrical grid and use secondary rechargeable batteries to store energy for these applications. However, the use of electrical grids to distribute energy to secondary batteries is not a perfect substitute for today’s system of combined use of grid and energy carrying fuels, namely because of insufficient energy density of secondary batteries limiting the practical range and / or duration in the aforementioned applications. This hasprompted industry to explore energy carriers such as aluminum as highly energy dense materials suitable for carrying the energy produced by renewable energy generation.

[0004] Aluminum-water oxidation reaction can be used to produce hydrogen as well as directly electrical energy, the latter of which occurs in aluminum-air primary batteries via galvanic corrosion. Typically, high-purity aluminum or specially alloyed aluminum with gallium, indium or other metals is required for aluminum-air cells. This is because the galvanic corrosion of impure aluminum preferentially produces a hydrogen evolution reaction at the sites of the impurity on the aluminum metal, particularly as the reaction sites become obstructed by aluminum hydrates during the course of the reaction. Requiring high-purity aluminum for such reactions reduces the economic viability of aluminum as an energy carrier. Aluminum benefits from an extremely high volumetric energy density of 23kWh / L, more than double that of gasoline and over ten times compressed and liquified hydrogen storage, while also having a high gravimetric specific energy of 8.5kWh / kg comparable to gasoline. Aluminum as an energy carrier also has the advantage of being highly stable, inherently safe, capable of storing energy indefinitely, not suffering from direct losses during transport, and being transportable with existing infrastructure. The aluminum-water oxidation reaction produces either directly electrical energy or hydrogen gas along with heat and a by-product of an aluminate liquor, such as sodium aluminate when sodium hydroxide is used as aluminum oxide layer stripping agent in the energy conversion reaction. From this aluminate liquor an aluminum hydrate such as aluminum trihydrate or aluminum monohydrate precipitates. As is typical in the Bayer process, this aluminum hydrate can then be calcined to produce alumina. Alumina is the primary intermediate input into virgin aluminum production. An energy carrier with complete circularity can be achieved using the aluminum-water oxidation reaction. Without the benefit of the teachings of this disclosure a significant disadvantage of using aluminum as an energy carrier is the emission of CO2 and other harmful emissions in the aluminum smelting process which is deleterious to the environmental benefits of aluminum as an energy carrier. Moreover, due to the requirement of high purityaluminum for traditional aluminum energy reactions the overall cost of the aluminum fuel cycle is prohibitive.

[0005] The Hall-Heroult process is the dominant method of producing virgin aluminum but suffers from the direct production of CO2 from the consumption of the carbon coke anode in the Hall-Heroult electrolysis cell. To resolve this the aluminum industry has undertaken significant effort to create ‘inert’ anode materials which do not directly emit CO2 in the electrolysis process. Candidate inert anode materials do not emit CO2 during electrolysis, withstand cell vibrations, hold their own weight, are resistant to thermal shock, are stable in oxygen, survive the cryolite bath as well as temperatures above 900°C. To meet the current needs of the aluminum industry inert anodes must also have a polarization voltage of < 0.5V at 0.8amps / cm2with a continuous voltage drop no lower than the carbon coke anode. Most importantly, the aluminum industry requires the inert anode to exhibit an erosion rate of < 20mm per year so as to produce primary-grade aluminum with impurities meeting the current standard of < 0.1% iron and < 0.2% silicon, meeting the 99.7% purity required to be a ‘good delivery’ bar at the London Metals Exchange. In selecting the material for the inert anode there exists a tradeoff between the corrosion resistance of the inert anode (and therefore the resultant aluminum metal purity) and its conductivity (and therefore energy requirements). Today, inert anode electrolysis cells explicitly trade off conductivity to achieve the corrosion resistance required for the 99.7% purity good deliver requirements. The 99.7% purity requirement arises from the common practice of the subsequent alloying of 99.7% pure primary aluminum to tight compositional specifications to achieve material properties desirable in common aluminum uses such as structural and packaging applications. Alloying requires high purity aluminum feedstock as even trace amounts of impurities such as iron or lead can degrade the desired mechanical and corrosion resistance properties. High purity aluminum provides for better quality control and consistency in its alloys. The development of an inert anode for the Hall-Heroult process is significantly restricted by the requirement for a high purity output. Therefore, selecting an inert anode material that meets all other requirements while simultaineously meeting the stringentpurity requirment for primary aluminum can be considered the most significant technical challenge to the development of a zero emissions Hall-Heroult process.

[0006] Another primary aluminum smelting process uses a candidate for zero emissions production of primary aluminum is carbothermic reduction, including the most promising variation Carbothermo-Chlorination Reduction (CCR). In CCR, alumina produced from the dehydration and calcination of an aluminum hydrate alongside carbon is fed into a chlorination process which utilizes a chlorinating agent combined with a catalyst and reductant at an elevated temperature. The products of this reaction are fed into a condensation system which recovers heat using a heat exhanger and condenses solid impure aluminum chloride. Other by-products such as silicon tetrachloride and titanium tetrachloride are directed to a rectification and condensation process for pruification. The solid aluminum chloride is typically contaminated with iron chloride, other impurities such as sulfur, and non-aluminum metal chlorides. This requires purification steps such as blending operations where powdered metals, such as iron, are combined with the impure aluminum chloride and then fed into a multi-stage sublimation process and a granulated metal reactor to produce high purity aluminum chloride gas. The high purity aluminum chloride gas is then condensed into a solid which is dissolved into an electrolyte in a closed smelting cell for the electrolysis of aluminum and chlorine. The chlorine is then recovered for re-use and the high concentration stream of CO produced during chlorination is either emitted or combusted for energy recovery and the resultant CO2 is sequenstered using carbon capture technology. The CCR process has the advantage over direct carbothermic reduction as there is no competing reaction of alumina to aluminum carbide over aluminum metal. In both carbothermic reduction and CCR the biggest challenge to the viability of the process is the purity of the Aluminum metal end product. In carbothermic reduction the purity challenge is associated with the impurities in the carbon source and the decarbonization of the aluminum carbide at high recoveries. In CRR the purity challenge is associated with the impurities in the carbon source and impurities introduced by chlorination. Both processes require significantadded steps, complexity, and energy to produce 99.7% high purity primary aluminum and the current non-use of these processes can be largely attributed to this challenge.

[0007] Additionally, the use of inert anodes in the Hall-Heroult process and CRR both provide the potential to reduce both the capital expenditure of the smelting plant and its operating expenditure. For the former, inert anodes significantly reduce the carbon cost of primary aluminum smelters and require changing less frequently thereby reducing labour costs, which estimates say will provide a 15% reduction in operating costs. The CCR process is also being investigated as a way to utilize alumina sources that are less pure than bauxite ore and to eliminate the environmentally deleterious red mud produced by the reduction of bauxite in the Bayer process. The CCR process also benefits from a smaller smelting cell size and potentially capital cost reductions of 50-70%. However, the environmental and economic savings promised by both of these smelting processes and the viability of aluminum as an energy carrier are harmed by today’s requirement of high purity aluminum in aluminum to energy reactions and the technical challenges of producing high purity aluminum from Hall-Heroult inert anode cells and carbothermic reduction processes.

[0008] The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.SUMMARY

[0009] A method of manufacturing a smelting anode is disclosed. A solid aluminum hydrate and solid impurity is precipitated from an aluminate solution. The non-aluminum impurity is separated, and smelting anode is cast therefrom. A method of creating an energy carrier using impure aluminum produced by a smelting cell is also disclosed.

[0010] In a first embodiment, a method of manufacturing a smelting anode is provided. The method comprising: precipitating, from an aluminate solution, a solid aluminum hydrate and at least one solid impurity, wherein the at least one solid impuritycomprises a first metal selected from copper, nickel, iron and combinations thereof; separating the at least one solid impurity from the solid aluminum hydrate; and casting a smelting anode from the at least one solid impurity, wherein the smelting anode comprises at least 40% (m / m) of the first metal.

[0011] In a second embodiment, a method of manufacturing an aluminum energy carrier is provided. The method comprising: reducing alumina to impure aluminum metal; casting the impure aluminum into an aluminum energy carrier, the aluminum energy carrier being a solid, a foam, a pellet, or a powder; and wherein the impure aluminum metal and the aluminum energy carrier each comprise aluminum and at least 1% (m / m) of a non-aluminum material.

[0012] This brief description of the invention is intended only to provide a brief overview of subject matter disclosed herein according to one or more illustrative embodiments, and does not serve as a guide to interpreting the claims or to define or limit the scope of the invention, which is defined only by the appended claims. This brief description is provided to introduce an illustrative selection of concepts in a simplified form that are further described below in the detailed description. This brief description is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] So that the manner in which the features of the invention can be understood, a detailed description of the invention may be had by reference to certain embodiments, some of which are illustrated in the accompanying drawings. It is to be noted, however, that the drawings illustrate only certain embodiments of this invention and are therefore not to be considered limiting of its scope, for the scope of the invention encompasses other equally effective embodiments. The drawings are not necessarily to scale, emphasis generally being placed upon illustrating the features of certain embodiments ofthe invention. In the drawings, like numerals are used to indicate like parts throughout the various views. Thus, for further understanding of the invention, reference can be made to the following detailed description, read in connection with the drawings in which:

[0014] FIG. 1 is a schematic diagram of an example of an aluminum smelting cell.

[0015] FIG. 2 is a flow diagram depicting one method of producing an aluminum energy carrier.

[0016] FIG. 3 is a schematic diagram of one example of an energy generating system.

[0017] FIG. 4 is a schematic diagram of a metal air battery for use in the energy generating system.

[0018] FIG. 5 is a flow diagram depicting one method of refurbishing spent aluminum.

[0019] FIG. 6 is a flow diagram of one method of producing an aluminum energy carrier.

[0020] FIG. 7 depicts two flow diagrams of methods for producing an aluminum energy carrier.

[0021] FIG. 8 depicts one method for manufacturing an aluminum smelting anode.DETAILED DESCRIPTION OF THE INVENTION

[0022] This disclosure teaches a system and method of using impure aluminum as an energy carrier through the production of a renewable “fuel grade” of aluminum metal, creating an aluminum energy carrier.

[0023] In one embodiment, an aluminum energy carrier is provided that comprises aluminum metal and at least 1% (m / m) non-aluminum materials (i.e. non-aluminum impurities). The basic and novel characteristic of the aluminum energy carrier is that it functions in an aluminum oxidation reaction to provide greater than 500Wh of energy per kilogram of aluminum metal. The non-aluminum materials are incorporated into the aluminum energy carrier during the smelting process. Conventionally, when selecting a smelting anode there is a tradeoff between conductivity and corrosion resistance. Theindustry currently favors high corrosion resistance to ensure the resulting aluminum metal reaches at least 99.7% (m / m) purity. This disclosure provides an aluminum energy carrier that comprises at least 1% (m / m) non-aluminum materials yet still produces greater than 500Wh of energy per kilogram of aluminum metal. Accordingly, a high conductivity smelting anode may be used, thereby reducing the cost of both the smelting anode and the resulting aluminum metal.

[0024] Referring to FIG. 1 an aluminum smelting cell 100 is depicted. The aluminum smelting cell 100 comprises a plurality of smelting anodes 102, a cathode 104, an electrolyte 106 and a feedstock 108 of alumina. In one embodiment, the electrolyte 106 is molten cryolite (Na3AlF6) or KF-NaF-AIFy AlCh-NaCl-KCl or EMIM-Cl-AICk wherein EMIM is l-ethyl-3-methylimidazolium cation. In a conventional smelting cell, the cathode is formed of a consumable material, such as carbon, which is oxidized to carbon dioxide as the alumina is reduced to aluminum metal 110. The aluminum metal 110 is subsequently collected and cast into a commercial product. In other conventional embodiments, the anode is formed of a corrosion resistant material that seeks to minimize chemical change during electrolysis (i.e. an inert anode). The inert anode is carbon- free. Conventionally, great care is taken to ensure the smelting anode 102 is selected to avoid contaminating the resulting aluminum metal 110 and thereby produce aluminum that is at least 99.7% (m / m) pure. To avoid contaminating the aluminum metal, inert anodes are typically selected from materials containing <40% (m / m) copper or similarly high conductivity materials such as nickel or iron. Such high purity aluminum is believed to be necessary to function as an energy carrier in, for example, aluminum metal air batteries and is standard for aluminum’s use in structural applications.

[0025] In contrast with conventional aluminum smelting cells, the aluminum smelting cell 100 uses a smelting anode 102 that comprises at least one of Al, Pt, Au, Ag, Cu, Pb, Sn, Ni, Co, Fe, Zn, Mn, Ti and Mg, with >40% (m / m) of copper, nickel, iron or a combination thereof. In one embodiment, the cathode 104 is a non-carbon cathode or wetted TiB2 cathode. During electrolysis, the non-aluminum materials in the smeltinganode 102 are incorporated into the aluminum metal 110 such that the resultant aluminum metal purity is <99.7%. The incorporation of >0.3% (m / m) of non-aluminum materials in the smelting cell is distinct from the conventional practice of alloying high purity aluminum >99.7% (m / m).

[0026] In some embodiments, the smelting anode 102 is an inert anode with at least 40% (m / m) of a first metal that is copper, iron, nickel or a combination thereof and at least one second metal that is not copper, nickel or iron. The second metal is present in a concentration of >1%, >2%, >5%, >10%, >15%, >20%, >25, >30%, >35%, >40%, >45%, >50% or >60% (m / m). Examples of the second metal include Al, Pt, Au, Ag, Pb, Sn, Co, Zn, Mn, Cr, Ti, Mg and combinations thereof.

[0027] In some embodiments, the smelting anode 102 consist of 100% of the first metal; 95-99% (m / m) of the first metal and from 1-5% (m / m) of the second metal; 95- 98% (m / m) the first metal and from 2-5% (m / m) of the second metal; 90-98% (m / m) the first metal and from 2-10% (m / m) of the second metal; 85-98% (m / m) the first metal and from 2-15% (m / m) of the second metal; 80-98% (m / m) the first metal and from 2-20% (m / m) of the second metal; 75-98% (m / m) the first metal and from 2-25% (m / m) of the second metal; 70-98% (m / m) the first metal and from 2-30% (m / m) of the second metal; 65-98% (m / m) the first metal and from 2-35% (m / m) of the second metal; 60-98% (m / m) the first metal and from 2-40% (m / m) of the second metal; 55-98% (m / m) the first metal and from 2-45% (m / m) of the second metal; 50-98% (m / m) the first metal and from 2- 50% (m / m) of the second metal; 45-98 (m / m) of the first metal and from 2-55% (m / m) of the second metal or 40-98% (m / m) of the first metal and from 2-60% (m / m) of the second metal.

[0028] In some embodiments, the smelting anode 102 consists of 40-98% (m / m) of the first metal and a balance which is the second metal, from 45-98% (m / m) of the first metal and a balance which is the second metal, 50-99% (m / m) the first metal and a balance which is the second metal; 55-99% (m / m) the first metal and a balance which is the second metal; 60-99% (m / m) the first metal and a balance which is the second metal; 65-99% (m / m) the first metal and a balance which is the second metal; 70-99% (m / m) thefirst metal and a balance which is the second metal; 75-99% (m / m) the first metal and a balance which is the second metal; 80-99% (m / m) the first metal and a balance which is the second metal; 85-99% (m / m) the first metal and a balance which is the second metal; 90-99% (m / m) the first metal and a balance which is the second metal; 95-99% (m / m) the first metal and a balance which is the second metal or 98-99% (m / m) the first metal and a balance which is the second metal.

[0029] Examples of suitable materials which form smelting cathode 104 include carbon / graphite, TiB2, or TiB2-carbon composites.

[0030] Referring to FIG. 2, a method 200 is depicted therein. In step 202 of method 200, alumina is reduced to impure aluminum metal 110 using, for example, the aluminum smelting cell 100 and the smelting anode 102. The alumina may be impure alumina that comprises >1%, >2%, >5%, >10%, >15%, >20%, >25, >30%, >35%, >40%, >45% or >50% (m / m) non-alumina materials, including Cu, Fe, Ni, Pt, Au, Ag, Pb, Sn, Co, Zn, Mn, Cr, Ti, Mg and combinations thereof. In another embodiment, the alumina may be substantially pure (e.g. >99.7% (m / m)) but non-aluminum impurities are incorporated from the use of the impure smelting anode 102. In step 204, the impure aluminum metal 110 is cast into an aluminum energy carrier. Conventional methods for casting molten aluminum into specific forms are well known in the art and include molding, die casting, centrifugal casting, continuous casting, direct chill casting. The aluminum energy carrier may be a solid metal, a foam, a pellet, or a powder. Examples of suitable aluminum energy carriers include anodes, such as anodes used in metal air batteries.

[0031] In some embodiments, the aluminum energy carrier consist of 95-99% (m / m) aluminum and from 1-5% (m / m) non-aluminum materials; 95-98% (m / m) aluminum and from 2-5% (m / m) non-aluminum materials; 90-98% (m / m) aluminum and from 2-10% (m / m) non-aluminum materials; 85-98% (m / m) aluminum and from 2-15% (m / m) non- aluminum materials; 80-98% (m / m) aluminum and from 2-20% (m / m) non-aluminum materials; 75-98% (m / m) aluminum and from 2-25% (m / m) non-aluminum materials; 70- 98% (m / m) aluminum and from 2-30% (m / m) non-aluminum materials; 65-98% (m / m) aluminum and from 2-35% (m / m) non-aluminum materials; 60-98% (m / m) aluminumand from 2-40% (m / m) non-aluminum materials; 55-98% (m / m) aluminum and from 2- 45% (m / m) non-aluminum materials or 50-98% (m / m) aluminum and from 2-50% (m / m) non-aluminum materials.

[0032] In some embodiments, the aluminum energy carrier consists of 50-99% (m / m) aluminum and a balance which is non-aluminum materials; 55-99% (m / m) aluminum and a balance which is non-aluminum materials; 60-99% (m / m) aluminum and a balance which is non-aluminum materials; 65-99% (m / m) aluminum and a balance which is non-aluminum materials; 70-99% (m / m) aluminum and a balance which is non- aluminum materials; 75-99% (m / m) aluminum and a balance which is non-aluminum materials; 80-99% (m / m) aluminum and a balance which is non-aluminum materials; 85- 99% (m / m) aluminum and a balance which is non-aluminum materials; 90-99% (m / m) aluminum and a balance which is non-aluminum materials; 95-99% (m / m) aluminum and a balance which is non-aluminum materials or 98-99% (m / m) aluminum and a balance which is non-aluminum materials.

[0033] In some embodiments, the aluminum energy carrier consists essentially of aluminum and from 1-50% (m / m) non-aluminum materials; aluminum and from 2-50% (m / m) non-aluminum materials; aluminum and from 5-50% (m / m) non-aluminum materials; aluminum and from 10-50% (m / m) non-aluminum materials; aluminum and from 15-50% (m / m) non-aluminum materials; aluminum and from 20-50% (m / m) non- aluminum materials; aluminum and from 25-50% (m / m) non-aluminum materials; aluminum and from 30-50% (m / m) non-aluminum materials; aluminum and from 35- 50% (m / m) non-aluminum materials; aluminum and from 40-50% (m / m) non-aluminum materials or aluminum and from 45-50% (m / m) non-aluminum materials. Examples of non-aluminum materials include Cu, Fe, Ni, Pt, Au, Ag, Pb, Sn, Co, Zn, Mn, Cr, Ti, Mg, Si, and combinations thereof.

[0034] Referring again to FIG. 2, once the aluminum energy carrier has been formed in step 204, the aluminum energy carrier may be transported to a distal location in step 206. For example, the aluminum energy carrier may be cast into the form of analuminum anode for a metal air battery. The aluminum anode is then transported to a distal location for sequent use in an energy generating device.

[0035] In step 208, the aluminum energy carrier is incorporated into an energy generating device. The energy generating device releases electrical, thermal, and / or hydrogen gas from the aluminum energy carrier during an aluminum oxidation reaction. Examples of suitable energy generating devices include metal air batteries, and aluminum- water high temperature reactors.

[0036] Referring to FIG. 3, one example of an energy generating system 300 is schematically depicted. The system 300 comprises an air metal battery 302, an air blower 304, and / or an oxygen supply 306 and a carbon dioxide scrubber 308. An electrolyte tank 310 with an electrolyte with a filter 312 is also present. Commonly electrolytes include, for example, aqueous NaOH or KOH solutions. A coolant system with a heat exchanger 314 and pump 316 is provided. An electrolyte pump 318 sends electrolyte through the air metal battery 302 and a gas separator 320. A knockout tank 322 and hydrogen disposal system 324 are also present. FIG. 4 depicts an example of the air metal battery 302 in further detail. The aluminum energy carrier is present as anode 400 and a cathode 402 is proximate to, but spaced from, the anode 400.

[0037] In one embodiment, a metal air battery is provided that incorporates any one of the aluminum energy carriers disclosed in this specification. The metal air battery produces hydrogen gas and thermal energy or electrical energy and thermal energy. The aluminum energy carrier may be, for example, a solid disc, pellets, a powder or a foam.

[0038] In another embodiment, an aluminum-oxidation reactor is provided that incorporates any one of the aluminum energy carriers disclosed in this specification. The aluminum oxidation reactor produces an aluminate solution that consists, or consists essentially of, an aluminum hydrate and from 1-50% (m / m), from 1-25% (m / m), or from 1-10% (m / m) or from 1-5% (m / m) non-aluminum impurities. Examples of such nonaluminum impurities include Pt, Au, Ag, Cu, Pb, Sn, Ni, Co, Fe, Zn, Mn, Ti, Cr, Si, and Mg.

[0039] Referring to FIG. 5, method 500 is depicted wherein, after step 208 of method 200 (see FIG. 2), the energy generating device is operated in step 502 and energy is generated during an aluminum oxidation reaction. This reaction produces the aforementioned aluminate solution. In step 503, solid aluminum hydrate and solid nonaluminum impurities are precipitated from the aluminate solution. For example, the precipitation may by induced by seeding, settling, mechanical separation, stirring, etc. In step 504, the solid aluminum hydrate and solid non-aluminum impurities are collected (e.g. filtering, mechanical separation, etc.). In step 506, the solid aluminum hydrate and solid non-aluminum impurities are calcinated to produce calcination products. In step 508, the calcination products are transported from the location where the energy was consumed to a processing plant where the resulting material is refurbished into fresh aluminum energy carrier (e.g. aluminum smelting cell 100). Specifically, the calcination products become input for feedstock 108 and the non-aluminum impurities undergo processing (see method 800) to create the smelting anode 102. In this manner, the output of step 508 becomes the input for method 200 (i.e. steps 202, 204 and 206). In some embodiments, step 508 (transporting to the processing plant) is performed prior to step 506 (calcinating the aluminum hydrate). This method provides a zero emissions circular method of carrying energy from a point of production to the point of energy demand using an impure aluminum energy carrier.

[0040] Referring to FIG. 6 and method 600 depicted therein, in step 602 alumina is reduced to impure aluminum metal as described with regard to step 202 of method 200 (see FIG. 2). In step 603, additional aluminum metal from another source (e.g. secondary aluminum from aluminum scrap) is combined with the impure aluminum metal resulting from step 602 (e.g. primary aluminum from a smelter). The additional aluminum metal may be pure aluminum metal (e.g. >99.7% (m / m)) or impure aluminum metal (i.e. atleast 1% (m / m) non-aluminum materials). In step 604, the impure aluminum metal is cast into an aluminum energy carrier as described with regard to step 204 (see FIG. 2).

[0041] Referring to FIG. 7 and method 700a depicted therein, in step 701 alumina is chlorinated in the presence of impurities (including, but not limited to Pt, Au, Ag, Cu, Pb, Sn, Ni, Co, Fe, Zn, Mn, Ti, Mg, S, Cr, Fe, Si and / or carbonates) to produce impure aluminum chloride. For example, a chlorinating agent (e.g. NaCl, KC1, NiCl, etc.) and chlorine gas are combined in a reactor with alumina at 600-700 °C . Such reactors are known in the art. The impurities may be present in at least 1% (m / m) as described elsewhere in this specification. In step 702, the impure aluminum chloride is reduced in an aluminum smelting cell (e.g. aluminum smelting cell 100) to produce chlorine gas and impure aluminum metal. The impure aluminum metal comprises impurities as described elsewhere in this specification. This method removes a number of steps required in the prior art for the electrolysis of aluminum chloride. In step 704, the impure aluminum metal is cast into an aluminum energy carrier.

[0042] Referring again to FIG. 7 and method 700b depicted therein, method 700b is similar to method 700a except in that, in step 703, additional aluminum metal from another source is combined with the impure aluminum metal resulting from step 702. In one embodiment, the additional aluminum metal is secondary aluminum from aluminum scrap that comprises at least 1% (m / m) non-aluminum materials as described elsewhere in this specification.

[0043] FIG. 8 depicts a method 800 for manufacturing a smelting anode 102. In step 802, solid aluminum hydrate and solid impurities are precipitated from an aluminate solution. The solid impurities comprise the aforementioned first metal (Fe, Ni, Cu, and combinations thereof) and the second metal (Pt, Au, Ag, Pb, Sn, Co, Zn, Mn, Cr, Ti, Mg and combinations thereof). In one embodiment, at least two second metals are present. Step 802 is substantially similar to step 503 of method 500. The aluminate solution may be, for example, an aluminate solution produced in step 502 of method 500. The aluminate solution comprises at least 1% (m / m) of the impurities as recited elsewhere inthis specification. In step 804, the solid impurities are separated from the solid aluminum hydrate. Step 804 may be executed by filtering, mechanical separation, sifting, separation by size, weight. In embodiments wherein the amount of the first metal in the solid impurities is less than 40% (m / m), step 805 is performed wherein iron, nickel, copper or a combination thereof is added to produce a solid impurity with at least 40% (m / m) of the first metal. In some embodiments, aluminum is also added in step 805. In step 806, a smelting anode is cast from the solid impurities. Step 806 is substantially similar to step 204 except in that a smelting anode is cast, rather than an aluminum energy carrier.

[0044] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

What is claimed is:

1. A method of manufacturing a smelting anode, the method comprising: precipitating, from an aluminate solution, a solid aluminum hydrate and at least one solid impurity, wherein the at least one solid impurity comprises a first metal selected from copper, nickel, iron and combinations thereof; separating the at least one solid impurity from the solid aluminum hydrate; and casting a smelting anode from the at least one solid impurity, wherein the smelting anode comprises at least 40% (m / m) of the first metal.

2. The method as recited in in claim 1 , wherein the at least one solid impurity comprises a second metal selected from Pt, Au, Ag, Pb, Sn, Co, Zn, Mn, Ti, Cr, Mg or a combination thereof.

3. The method as recited in in claim 1, wherein the smelting anode comprises >40% (m / m) of copper, nickel, iron or a combination thereof.

4. The method as recited in in claim 1 , wherein the method comprises adding iron, nickel, copper, aluminum or a combination thereof to the at least one solid impurity, the adding occurring after the separating and before the casting.

5. The method as recited in in claim 1, wherein the at least one solid impurity comprises a second metal selected from Pt, Au, Ag, Cu, Pb, Sn, Co, Zn, Mn, Ti, Cr, Mg or a combination thereof.

6. The method as recited in claim 5, wherein the first metal is copper.

7. A method of manufacturing an aluminum energy carrier, the method comprising: reducing alumina to impure aluminum metal; casting the impure aluminum metal into an aluminum energy carrier, the aluminum energy carrier being a solid, a foam, a pellet, or a powder; and wherein the impure aluminum metal and the aluminum energy carrier each comprise aluminum and at least 1% (m / m) of a non-aluminum material.

8. The method as recited in claim 7, wherein the impure aluminum metal comprises at least 5% (m / m) of the non-aluminum material.

9. The method as recited in claim 7, wherein the non-aluminum material includes at least one of Pt, Au, Ag, Cu, Pb, Sn, Ni, Co, Fe, Zn, Mn, Cr, Ti, Si, and Mg.

10. The method as recited in claim 7, wherein the aluminum energy carrier is a solid anode.

11. The method as recited in claim 7, wherein the aluminum energy carrier is a solid anode in the form of a disc.

12. The method as recited in claim 7, wherein the reducing occurs in an aluminum smelting cell and is performed by electrolysis.

13. The method as recited in claim 7, wherein the reducing occurs by: chlorinating the alumina to form impure aluminum chloride; and reducing the impure aluminum chloride to form the impure aluminum metal.

14. The method as recited in claim 7, wherein the alumina is impure alumina that comprises at least 1% (m / m) of the non-alumina material.

15. The method as recited in claim 7, wherein the alumina and the impure aluminum metal comprises at least 5% (m / m) of the non-aluminum material.

16. The method as recited in claim 7, wherein the reducing occurs in an aluminum smelting cell that has a smelting anode and is performed by electrolysis, wherein the smelting anode is at least 40% (m / m) copper, nickel, or iron.

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