Integrated catalytic processes for converting aluminum metal into precipitated alumina trihydrate

Abstract

Processes for producing a precipitated aluminum trihydrate (ATH) product from scrap or waste aluminum metal include the steps of contacting the aluminum metal with an activating composition containing gallium and / or indium to form an activated aluminum composition, reacting the activated aluminum composition with water and an ionic salt, a hydroxide, and / or an acid to form hydrogen gas and a first reaction mixture comprising solid ATH and a first solid fraction, isolating the solid ATH and the first solid fraction from the first reaction mixture, contacting the solid ATH and the first solid fraction with an aqueous caustic solution to form a second reaction mixture containing dissolved sodium aluminate, removing a second solid fraction from the second reaction mixture to form a liquor solution, seeding the liquor solution with a seed material to precipitate ATH and form a suspension, isolating precipitated ATH from the suspension and washing the precipitated ATH to form an intermediate ATH product, optionally milling the intermediate ATH product, and drying the intermediate ATH product to form the precipitated ATH product. Concurrently with the production of ATH is the production of molecular hydrogen and significant amounts of heat / energy.

Description

[0001] INTEGRATED CATALYTIC PROCESSES FOR CONVERTING ALUMINUM METAL INTO PRECIPITATED ALUMINA TRIHYDRATE

[0002] REFERENCE TO RELATED APPLICATION

[0003] This application is being filed on October 9, 2025, as a PCT International Patent Application and claims the benefit of and priority to U.S. Provisional Patent Application No. 63 / 705,548, filed on October 10, 2024, the disclosure of which is incorporated herein by reference in its entirety.

[0004] FIELD OF THE INVENTION

[0005] The present disclosure is directed generally to catalytic processes for converting aluminum metal into alumina trihydrate (ATH), and more particularly, to converting scrap or waste aluminum metal into ATH concurrently with the production of molecular hydrogen (H2) and energy.

[0006] BACKGROUND OF THE INVENTION

[0007] Bauxite ore is a primary source of aluminum metal, which is produced in large quantities in basically three (3) very energy-intensive steps: refining bauxite to aluminum trihydroxide (ATH) in the so called “Bayer process” (which produces red mud waste and crude alumina trihydrate (“crude ATH”) and yields of about 50-60% depending on the composition of the bauxite ore); calcining this ATH to aluminum oxide (alumina) at high temperature; and reducing the oxide to aluminum metal in a melt flow electrolysis (via the Hall-Heroult electrolytic process). It is obvious from the high energy consumption needed to produce aluminum metal that a preferred technology should be the recycling of aluminum metal and suitable alloys again to aluminum metal. This is often not possible, and much aluminum metal or alloys thereof end up in landfills, and the energy still enclosed in the aluminum material is therefore lost.

[0008] The reaction of aluminum metal with water is very exothermic and provides hydrogen gas and heat, recovering at least part of the energy that went into the production of the metal. Molecular hydrogen or H2 gas is a highly desirable form of green energy and has been the subject of scientific research to find an affordable clean energy solution to use aluminum metal waste. This reaction of aluminum metal and water, however, is hindered by an oxide layer formed on the metal surface, which completely prevents the ability of the aluminum metal from substantially reacting with water.

[0009] As a side stream to the large aluminum metal industry, ATH is also produced for certain applications, e.g., as a filler in compounds to provide flame retardancy or thermal conductivity. This is either done directly in the first step described above, or by further refining the product of the first step (often called “crude ATH”) in a recrystallization process, also based on Bayer process technology, into highly purified and finely tailored precipitated alumina trihydrate at high purity levels, with specific morphology via particle size and surface area structure, commonly referred to in the industry as fine precipitated ATH.

[0010] In view of these factors, Applicant believes that it would be beneficial to produce a refined and more desirable purified ATH product in a recrystallization process concurrently with a H2 product stream from a scrap or waste aluminum metal feedstock. Accordingly, it is to these ends that the present invention is generally directed.

[0011] SUMMARY OF THE INVENTION

[0012] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify required or essential features of the claimed subject matter. Nor is this summary intended to be used to limit the scope of the claimed subject matter.

[0013] The present invention provides a process to use scrap or waste aluminum metal, which would otherwise go to a landfill, as a green source for the production of aluminum hydroxide. Instead of using the result of the Bayer process based on Bauxite mineral as a feedstock, waste material based on aluminum metal, which has reached the end of its life cycle, is the feedstock used to make ATH, at the same time regaining the energy enclosed in the aluminum feedstock in the form of heat and hydrogen gas. The oxide layer that ordinarily protects aluminum metal is overcome by using an activating composition that can permeate into the grain boundaries and / or subgrain boundaries of the aluminum metal, therefore disrupting the oxide layer formed on the metal surface and facilitating the reaction between aluminum and water. The resultant energy generated eliminates the need for further energy input into the process, whether from fossil fuels or otherwise. This enables ATH filler production to be part of the green circular economy by both reusing a scrap or waste material and utilizing the energy generated to eliminate the need for external energy sources.

[0014] Accordingly, a representative process for producing a precipitated alumina trihydrate (ATH) product from aluminum metal can comprise (i) contacting the aluminum metal with an activating composition comprising gallium and / or indium to form an activated aluminum composition, (ii) reacting the activated aluminum composition with water and an ionic salt, a hydroxide, and / or an acid to form hydrogen (H2) gas and a first reaction mixture comprising solid ATH and a first solid fraction, (iii) isolating the solid ATH and the first solid fraction from the first reaction mixture, (iv) contacting the solid ATH and the first solid fraction with an aqueous caustic solution to form a second reaction mixture containing dissolved sodium aluminate, (v) removing a second solid fraction from the second reaction mixture to form a liquor solution, (vi) seeding the liquor solution with a seed material to precipitate ATH and form a suspension, (vii) isolating precipitated ATH from the suspension and washing the precipitated ATH to form an intermediate ATH product, (viii) optionally, milling the intermediate ATH product, and (ix) drying the intermediate ATH product to form the precipitated ATH product. The resulting precipitated ATH product can be used as a flame retardant additive in polymer compositions for a variety of end-use applications, such as wire and cable applications.

[0015] Typically, the aluminum metal source is a scrap or waste aluminum metal, and concurrently with the production of ATH is the generation of significant amounts of both hydrogen gas and heat / energy.

[0016] Both the foregoing summary and the following detailed description provide examples and are explanatory only. Accordingly, the foregoing summary and the following detailed description should not be considered to be restrictive. Further, features or variations may be provided in addition to those set forth herein. For example, certain aspects may be directed to various feature combinations and sub-combinations described in the detailed description.

[0017] BRIEF DESCRIPTION OF THE FIGURE FIG. 1 is a schematic flow diagram of an integrated catalytic process for converting aluminum metal into alumina trihydrate consistent with aspects of the present disclosure.

[0018] DEFINITIONS

[0019] To define more clearly the terms used herein, the following definitions are provided. Unless otherwise indicated, the following definitions are applicable to this disclosure. If a term is used in this disclosure but is not specifically defined herein, the definition from the IUPAC Compendium of Chemical Terminology, 2nd Ed (1997), can be applied, as long as that definition does not conflict with any other disclosure or definition applied herein, or render indefinite or non-enabled any claim to which that definition is applied. To the extent that any definition or usage provided by any document incorporated herein by reference conflicts with the definition or usage provided herein, the definition or usage provided herein controls.

[0020] Herein, features of the subject matter are described such that, within particular aspects, a combination of different features can be envisioned. For each and every aspect and each and every feature disclosed herein, all combinations that do not detrimentally affect the designs, compositions, or processes / methods described herein are contemplated and can be interchanged, with or without explicit description of the particular combination. Accordingly, unless explicitly recited otherwise, any aspect or feature disclosed herein can be combined to describe inventive designs, compositions, or processes / methods consistent with the present disclosure.

[0021] While compositions and processes / methods are described herein in terms of “comprising” various components or steps, the compositions and processes / methods also can “consist essentially of’ or “consist of’ the various components or steps, unless stated otherwise. The terms “a,” “an,” and “the” are intended to include plural alternatives, e.g., at least one, unless otherwise specified.

[0022] Generally, groups of elements are indicated using the numbering scheme indicated in the version of the periodic table of elements published in Chemical and Engineering News, 63(5), 27, 1985. In some instances, a group of elements can be indicated using a common name assigned to the group; for example, alkali metals for Group 1 elements, alkaline earth metals for Group 2 elements, and so forth. The term “contacting” is used herein to refer to materials or components which can be blended, mixed, slurried, dissolved, reacted, treated, seeded, compounded, or otherwise contacted or combined in some other manner or by any suitable method. The materials or components can be contacted together in any order, in any manner, and for any length of time, unless otherwise specified.

[0023] Aluminum trihydroxide, Al(0H)3, also may be referred to herein as aluminum hydroxide or alumina trihydrate (or abbreviated as ATH).

[0024] Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the invention, the typical methods and materials are herein described.

[0025] All publications and patents mentioned herein are incorporated herein by reference in their entirety for the purpose of describing and disclosing, for example, the constructs and methodologies that are described in the publications and patents, which might be used in connection with the presently described invention.

[0026] Several types of ranges are disclosed in the present invention. When a range of any type is disclosed or claimed, the intent is to disclose or claim individually each possible number that such a range could reasonably encompass, including end points of the range as well as any sub-ranges and combinations of sub-ranges encompassed therein. As a representative example, the Na?O concentration of the aqueous caustic solution (or the second reaction mixture) in step (iv) of the disclosed processes can be in certain ranges in various aspects of this invention. By a disclosure that the Na?O concentration is in a range from 50 to 200 g / L (NaOH concertation expressed in terms of Na2O), the intent is to recite that the concentration can be any amount in the range and, for example, can include any range or combination of ranges from 50 to 200 g / L of Na?O, such as from 50 to 150 g / L, from 65 to 120 g / L, from 75 to 100 g / L, from 100 to 180 g / L, from 120 to 170 g / L, or from 130 to 160 g / L of Na?O, and so forth. Likewise, all other ranges disclosed herein should be interpreted in a manner similar to this example.

[0027] In general, an amount, size, formulation, parameter, range, or other quantity or characteristic is “about” or “approximate” whether or not expressly stated to be such. Whether or not modified by the term “about” or “approximately,” the claims include equivalents to the quantities or characteristics. DETAILED DESCRIPTION OF THE INVENTION

[0028] Disclosed herein are processes for the concurrent production of molecular hydrogen (H2, hydrogen gas), alumina trihydrate (ATH), and heat / energy from scrap or waste aluminum metal. The production of virgin aluminum metal on an industrial scale from bauxite ore using the Bayer process followed by the Hall-Heroult electrolytic process is an extensive, energy intensive, and costly process. Therefore, producing fine precipitated ATH directly from virgin aluminum metal would be non-sensical.

[0029] The current Bayer process for producing crude ATH, which is a raw material feedstock to make fine precipitated ATH, is likewise very expensive and energy intensive. Thus, an objective of this invention is to use scrap or waste aluminum metal rather than crude ATH as a feedstock to produce precipitated ATH.

[0030] Another objective is to produce molecular hydrogen (H2) from the aluminum metal, concurrently with the production of precipitated ATH.

[0031] Another objective is to produce molecular hydrogen (H2) from the aluminum metal, concurrently with the production of precipitated ATH, with the use of an activating composition comprising gallium and / or indium.

[0032] Another objective is to recover the activating composition comprising gallium and / or indium from the first reaction mixture, and recycle the recovered activating composition for use as a portion of the activating composition in step (i), since the activating composition is expensive and can be detrimental to the final precipitated ATH product if not removed.

[0033] Another objective is to produce molecular hydrogen (H2) from the aluminum metal, concurrently with the production of precipitated ATH at a yield of approximately 2.5-3.0 kg of ATH per kg of initial (scrap or waste) aluminum metal.

[0034] Another objective is to convert the conventional process of producing fine precipitated ATH from crude ATH, which is an endothermic process, to a process of producing precipitated ATH from scrap or waste aluminum metal, which is an exothermic process, producing significant amounts of heat / energy.

[0035] Another objective is to produce green ATH from scrap or waste aluminum metal, which would otherwise go to a landfill, and to do so in a process that is energy self- sufficient, in which no external energy source is needed. Another objective is to produce the precipitated ATH as a dry, free flowing powder, with a controlled average particle size that is suitable for use as a flame retardant additive in various products, such as in polymer formulations for wire / cable applications, as an additive in thermal management applications, and as a raw material for the production of specialty aluminum oxides. Non-limiting examples for use of such aluminum oxides include polishing agents, specialty ceramics, absorbents for water purification, catalyst carriers or supports, and the like.

[0036] PROCESSES FOR PRODUCING ALUMINA TRIHYDRATE

[0037] Disclosed herein are processes for producing a precipitated aluminum trihydrate (ATH) product from aluminum metal, and these processes can comprise (or consist essentially of, or consist of) (i) contacting the aluminum metal with an activating composition comprising gallium and / or indium to form an activated aluminum composition, (ii) reacting the activated aluminum composition with water and an ionic salt, a hydroxide, and / or an acid to form hydrogen (H2) gas and a first reaction mixture comprising solid ATH and a first solid fraction, (iii) isolating the solid ATH and the first solid fraction from the first reaction mixture, (iv) contacting the solid ATH and the first solid fraction with an aqueous caustic solution to form a second reaction mixture containing dissolved sodium aluminate, (v) removing a second solid fraction from the second reaction mixture to form a liquor solution, (vi) seeding the liquor solution with a seed material to precipitate ATH and form a suspension, (vii) isolating precipitated ATH from the suspension and washing the precipitated ATH to form an intermediate ATH product, (viii) optionally, milling the intermediate ATH product, and (ix) drying the intermediate ATH product to form the precipitated ATH product.

[0038] Generally, the features of the processes for producing the precipitated ATH product from aluminum metal (e.g., the activating composition, the contacting step to form the activated aluminum composition, the reaction and formation of hydrogen gas and the first reaction mixture, isolating solid ATH and the first solid fraction, the contacting step to form the second reaction mixture, the removing step, the seeding step, isolating precipitated ATH from the suspension, the milling step, and the drying step, among others) are independently described herein and these features can be combined in any combination to further describe the disclosed processes to produce precipitated ATH products from aluminum metal. Moreover, additional process steps can be performed before, during, and / or after any of the steps in any of the processes disclosed herein and can be utilized without limitation and in any combination to further describe these processes, unless stated otherwise. Further, any precipitated ATH products produced in accordance with the disclosed processes are within the scope of this disclosure and are encompassed herein.

[0039] Referring first to step (i), the aluminum metal can be contacted with an activating composition comprising gallium and / or indium to form an activated aluminum composition. Typically, the source of the aluminum metal that is the feedstock in step (i) is a scrap or waste aluminum metal, which can include any source that contains aluminum metal that cannot be recycled into aluminum metal. Thus, the (scrap or waste) aluminum metal can have any shape or configuration, non-limiting examples of which can include sheet like, spherical, oblong, or irregular, among other options. Depending upon the shape or configuration of the aluminum metal, the aluminum metal can have any suitable average particle size or average thickness. While not limited thereto, illustrative ranges for the average particle size or the average thickness of the aluminum metal can include from 0.1 to 100 mm, from 1 to 100 mm, from 5 to 100 mm, from 0.1 to 30 mm, from 1 to 30 mm, 3 to 30 mm, from 5 to 30 mm, from 0.1 to 10 mm, from 1 to 10 mm, or from 3 to 10 mm, and the like.

[0040] In some aspects, the (scrap or waste) aluminum metal can be an aluminum alloy. The aluminum alloy can comprise any number of different materials that may be alloyed with aluminum, including but not limited to, silicon, magnesium, manganese, copper, zinc, or tin, as well as combinations thereof. Generally, the amount of aluminum present in the aluminum alloy, when utilized as the source of the aluminum metal, is greater than or equal to 40 wt. %, greater than or equal to 50 wt. %, greater than or equal to 60 wt. %, greater than or equal to 70 wt. %, greater than or equal to 80 wt. %, greater than or equal to 90 wt. %, greater than or equal to 95 wt. %, greater than or equal to 99 wt. %, or greater than or equal to 99.99 wt. %, based on the total weight of the aluminum alloy.

[0041] Additionally or alternatively, the aluminum metal can have any suitable purity (e.g., based on the source of the scrap or waste aluminum metal), and this can range from a purity of aluminum in the aluminum metal of as low as 30-40 wt. % and up to and including purity levels of over 95-99 wt. %. Thus, for example, the aluminum metal can have a purity of at least 30 wt. % aluminum; alternatively, at least 40 wt. % aluminum; alternatively, at least 50 wt. % aluminum; alternatively, at least 60 wt. % aluminum; alternatively, at least 70 wt. % aluminum; alternatively, at least 80 wt. % aluminum; alternatively, at least 90 wt. % aluminum; alternatively, at least 92 wt. % aluminum; alternatively, at least 95 wt. % aluminum; alternatively, at least 98 wt. % aluminum; or alternatively, or at least 99 wt. % aluminum. The aluminum purity also can fall within a range between any of these purity values, such as an aluminum metal having a purity of 50 to 90 wt. % aluminum.

[0042] Aluminum products are often coated with a polymeric coating (e.g., paint). Thus, in an aspect, a polymeric coating is present on the surface of the (scrap or waste) aluminum metal. While not limited thereto, the polymeric coating can comprise a polyethylene, a polypropylene, a polyester, a polystyrene, an acrylic resin, a polyvinyl, a phenolic resin, an epoxy resin, or any combination thereof. When present, the polymeric coating on the aluminum metal surface may inhibit the activating composition comprising gallium and / or indium from contacting and activating the underlying aluminum metal. Thus, when a polymeric coating is present on the aluminum metal surface, it may be desirable to penetrate, remove, or otherwise disrupt any coatings disposed on the aluminum metal in order to expose or access the underlying aluminum metal.

[0043] Optionally, prior to step (i), the aluminum metal can be processed in a comminution device to reduce the average particle size or the average thickness of the aluminum metal to the sizes / dimensions disclosed herein. Typical comminution devices that can be utilized include an impact crusher, a hammer mill, a jet mill, a roll mill, a roll crusher, a jaw crusher, an ultrasonic device, and the like, and including combinations of two or more of these devices. Also optionally, prior to step (i), the aluminum metal can be subjected to any conventional shredding or fragmenting operation to form aluminum metal fragments. Typically, shredding or fragmenting operations that can be utilized include cutting, milling, shredding, fragmenting, and the like, and including combinations of two or more of these operations.

[0044] The resulting aluminum metal fragments can subsequently be compressed together in a die with a press to form a pellet having any suitable thickness, diameter, and / or width. While not limited thereto, the pellet can have an average cross-sectional transverse dimension (e.g., a diameter or width) of greater than or equal to 0.5 mm and less than or equal to 5 mm, an average thickness of greater than or equal to 1 mm and less than or equal to 5 mm, and / or a mass of greater than or equal to 0.3 g and less than or equal to 5 g.

[0045] Contacting the aluminum metal with the activating composition in step (i) disrupts the naturally occurring oxide coating that is present on the surface of the aluminum metal, and prevents the oxide coating from reforming as the aluminum and water react in step (ii). The activating composition in step (i) can be a liquid eutectic mixture (i.e., a mixture that would remain in liquid form at room temperature) of gallium and indium or a close-to eutectic mixture (i.e., a mixture that would remain in a liquid and / or semi-liquid form at room temperature) of gallium and indium. In a non-limiting aspect, the activating composition can contain an amount of gallium in a range from 70 to 80 wt. % gallium, based on the total weight of the activating composition. Additionally or alternatively, the activating composition can contain an amount of indium in a range from 20 to 30 wt. % indium, based on the total weight of the activating composition.

[0046] In step (i), the aluminum metal can be contacted with the activating composition comprising gallium and / or indium, thereby forming an activated aluminum composition. Contacting the aluminum metal with the activating composition comprising gallium and / or indium in step (i) can comprise applying (e.g., painting or spraying) a coating of the activating composition onto the aluminum metal to form the activated aluminum composition. The aluminum metal also can be dipped or submerged into a container of the activating composition. The activating composition initially wets the surface of the aluminum metal, but over time it permeates into the grain boundaries and / or subgrain boundaries of the aluminum, thereby activating the aluminum and forming the activated aluminum composition.

[0047] Alternatively, the activating composition comprising gallium and / or indium may be incorporated into an alloy with the aluminum. Thus, contacting the aluminum metal with the activating composition can comprise melting / mixing the aluminum metal and the activating composition together to form an alloy mixture and solidifying the alloy mixture to form the activated aluminum composition. While not wishing to be bound by theory, during solidification, the gallium and / or indium of the activating composition tend to migrate to the grain boundaries and / or subgrain boundaries of the aluminum, thereby activating the aluminum and forming the activated aluminum composition. Typically, the amount of the activating composition in the alloy mixture, based on the total weight of the alloy mixture, can be in a range from 0.1 to 50 wt. %, from 1 to 40 wt. %, from 5 to 30 wt. %, from 15 to 20 wt. %.

[0048] While not limited thereto, step (i) can be conducted (or the activated aluminum composition can be formed) at a temperature in a range 100 °C to 200 °C, from 110 °C to 190 °C, from 120 °C to 180 °C, from 130 °C to 170 °C, or from 140 °C to 160 °C. Step (i) can be conducted (or the activated aluminum composition can be formed) over a wide range of time periods, such as from 1 hr to 240 hr, from 24 hr to 168 hr, from 48 hr to 120 hr, or from 72 hr to 120 hr, but is not limited solely to these time periods. Many factors can influence the appropriate time period for step (i), such as temperature, pressure, the amount and characteristics of the aluminum metal, and the amount and characteristics of the activating composition.

[0049] As previously mentioned, in step (i), the gallium and / or indium of the activating composition may permeate through the one or more grain boundaries and / or subgrain boundaries of the aluminum in order to activate the aluminum metal. In step (i), once activation occurs, an activated aluminum composition is formed and contains activated aluminum. The activated aluminum may be more reactive towards water when compared to aluminum that has not been exposed to an activating composition of gallium and / or indium. Thus, in an aspect, the aluminum metal in the activated aluminum composition in step (i) is more reactive towards water than aluminum metal that has not been contacted with the activating composition comprising gallium and / or indium.

[0050] Optionally, prior to step (ii), the activated aluminum composition can be milled to form activated aluminum particles. The activated aluminum particles can be suspended in any suitable carrier fluid to form a slurry. Thus, the activated aluminum composition can be present as a slurry of activated aluminum particles. Alternatively, or additionally, the activated aluminum particles can be in a solid form (e.g., a powder). Thus, the activated aluminum composition can be present as a powder comprising activated aluminum particles.

[0051] Referring now to step (ii), the activated aluminum composition is reacted with water and an ionic salt, a hydroxide, and / or an acid to form hydrogen (H2) gas and a first reaction mixture comprising solid ATH and a first solid fraction. While other reactions can be occurring in step (ii), it is believed that the following reactions (1) and (2) are the primary reactions that occur in step (ii):

[0052] 2 Al + 6 H2O ==> 3 H2 + 2 A1(OH)3(1)

[0053] 2 Al + 4 H2O ==> 3 H2+ 2 A10(0H) (2)

[0054] A particular benefit of the processes disclosed herein is the concurrent production of molecular hydrogen (H2, hydrogen gas), precipitated alumina trihydrate (ATH), and heat / energy from the scrap or waste aluminum metal. In step (ii), hydrogen (H2) gas is formed, and the hydrogen (H2) gas can be captured or collected for any suitable end-use, whether as a fuel or for use in a multitude of chemical processes. Step (ii) is highly exothermic and produces heat / energy. In some aspects, for instance, the heat / energy is converted to steam, such that the thermal energy is recovered and used. Advantageously, in other aspects, heat generated in step (ii) can be utilized in downstream operations or process steps discussed further hereinbelow, as needed, thereby reducing the energy consumption needed for the respective operation or process step. Although not limited thereto, at least 50% of the heat / energy produced in step (ii) can be utilized within the process, and more often, at least 60%, at least 75%, at least 90%, or at least 95% of the heat / energy produced in step (i) can be utilized within the process.

[0055] The ionic salt, when present in step (ii), can be any suitable ionic salt, including sodium chloride, potassium chloride, sodium bicarbonate, magnesium chloride, calcium chloride, aluminum sulfate, and the like, and including combinations of two or more of these ionic salts. The hydroxide, when present in step (ii), can be any suitable hydroxide, including sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, and the like, and including combinations of two or more of these hydroxides. The acid, when present in step (ii), can be any suitable acid, including hydrochloric acid, sulfuric acid, acetic acid, and the like, and including combinations of two or more of these acids. In one aspect, the activated aluminum composition is reacted with water and the ionic salt, while in another aspect, the activated aluminum composition is reacted with water and the hydroxide, and in yet another aspect, the activated aluminum composition is reacted with water and the acid.

[0056] In some aspects, the ionic salt, the hydroxide, and / or the acid in step (ii) is dissolved and / or suspended in water. The concentration of the ionic salt, the hydroxide, and / or the acid dissolved in the water can be greater than or equal to 0.1 M, greater than or equal to 0.5 M, greater than or equal to 1 M, greater than or equal to 1.5 M, greater than or equal to 2 M, greater than or equal to 2.5 M, greater than or equal 3 M, greater than or equal to 3.5 M, greater than or equal to 4 M, greater than or equal to 4.5 M, greater than or equal to 5 M, greater than or equal to 6 M, greater than or equal to 7 M, greater than or equal to 8 M, or greater than or equal to 9 M (molarity in mol / L). In certain aspects, the concentration of the ionic salt, the hydroxide, and / or the acid dissolved in water can be less than or equal to a solubility limit of the ionic salt, the hydroxide, and / or the acid in the water. For example, the concentration of the ionic salt, the hydroxide, and / or the acid dissolved in the water can be less than or equal to 10 M, less than or equal to 9 M, less than or equal to 8 M, less than or equal to 7 M, less than or equal to 6 M, less than or equal to 5 M, less than or equal to 4.5 M, less than or equal to 4 M, less than or equal to 3.5 M, less than or equal to 3 M, less than or equal to 2.5 M, less than or equal to 2 M, less than or equal to 1.5 M, less than or equal to 1 M, or less than or equal to 0.5 M. Combinations of the above recited ranges are also possible, for instance, the concentration of the ionic salt, the hydroxide, and / or the acid in the water can be greater than or equal to 0.1 M and less than or equal to 10 M, greater than or equal to 1 M and less than or equal to 8 M, or greater than or equal to 4 M and less than or equal to 6 M. In an aspect, the ionic salt, the hydroxide, and / or the acid in step (ii) can be in a solid form (e.g., a powder) prior to use in step (ii).

[0057] The inclusion of the ionic salt, the hydroxide, and / or the acid in step (ii) serves several functions. First, the components of the activating composition (e.g., gallium and indium) may separate from one another during the course of the reaction in step (ii) and oxidize. While not wishing to be bound by theory, during step (ii), ionic cations (e.g., Na+) and / or anions (e.g., CF) of the ionic salt, the hydroxide, and / or the acid may adhere and / or otherwise aggregate on the surface of the activating composition. The adherence of the ionic cations and / or anions to the surface of the activating composition can prevent separation and / or oxidation of the components of the activating composition (e.g., gallium and indium).

[0058] Beneficially, the use of the ionic salt, the hydroxide, and / or the acid may also decrease the amount of water necessary to reach the maximum yield of hydrogen, or conversely increase the hydrogen yield for the given amount of water. While not wishing to be bound by theory, when a hydroxide is utilized in step (ii) (e.g., NaOH), it can increase the alkalinity of the water reactant, therefore favoring the formation of ATH, and driving the reaction to completion. This is advantageous because a high yield of ATH can be accomplished in step (ii), while simultaneously conserving water.

[0059] The first reaction mixture in step (ii) comprises solid ATH and the first solid fraction. In an aspect, the first reaction mixture can further comprise (in addition to ATH) the activating composition comprising gallium and / or indium, aluminum hydroxide oxide (A10(0H)), aluminum oxide (AI2O3), unreacted water, and / or excess and / or leftover ionic salt, hydroxide, and / or acid. The amount of water in the first reaction mixture at the end of step (ii) can be an amount greater than or equal to 1 wt. %, greater than or equal to 5 wt. %, greater than or equal to 10 wt. %, greater than or equal to 15 wt. %, or greater than or equal to 20 wt. %, based on the total weight of the first reaction mixture. Likewise, the amount of water in the first reaction mixture at the end of step (ii) can be an amount less than or equal to 25 wt. %, less than or equal to 20 wt. %, less than or equal to 15 wt. %, less than or equal to 10 wt. %, or less than or equal to 5 wt. %, based on the total weight of the first reaction mixture. Combinations of the above recited ranges are also possible, for instance, the first reaction mixture can comprise water in an amount between greater than or equal to 1 wt. % and less than or equal to 25 wt. %, between greater than or equal to 5 wt. % and less than or equal to 20 wt. %, or between greater than or equal to 10 wt. % and less than or equal to 15 wt. %, based on the total weight of the first reaction mixture. Often, it can be beneficial to have an amount of water sufficient to maintain a gel state, for instance, to facilitate easier separation.

[0060] In a further aspect of the processes for producing precipitated ATH, these processes optionally can include - after step (ii) - the steps of isolating the activating composition comprising gallium and / or indium from the first reaction mixture, and then recycling the isolated activating composition for use as a portion of the activating composition in step (i). Isolating and recycling the activating composition is beneficial because the activating composition comprising gallium and / or indium is expensive and reusing the gallium and / or indium improve the overall cost efficiency of the process. Any suitable technique can be used for isolating the activating composition from the first reaction mixture, non-limiting examples of which include filtering, settling, decanting, pressing, electrowetting, centrifuging, cycloning, hydrocycloning, or any combination thereof. Advantageously, greater than or equal to 95 wt. %, greater than or equal to 96 wt. %, greater than or equal to 97 wt. %, greater than or equal to 98 wt. %, greater than or equal to 99 wt. %, or greater than or equal to 99.9 wt. % of the activating composition can be isolated from the first reaction mixture. Likewise, less than or equal to 100 wt. %, less than or equal to 99.9 wt. %, less than or equal to 99 wt. %, less than or equal to 98 wt. %, less than or equal to 97 wt. %, or less than or equal to 96 wt. % of the activating composition can be isolated from the first reaction mixture. Combinations of the above recited ranges are also possible, for instance, between greater than or equal to 96 wt. % and less than or equal to 100 wt. %, between greater than or equal to 96 wt. % and less than or equal to 99 wt. %, or between greater than or equal to 98 wt. % and less than or equal to 99.9 wt. % of the activating composition can be isolated from the first reaction mixture.

[0061] In another aspect of the processes for producing precipitated ATH, these processes optionally can include - after step (ii) - the steps of isolating the excess and / or leftover ionic salt, hydroxide, and / or acid from the first reaction mixture, and then recycling the excess and / or leftover ionic salt, hydroxide, and / or acid for use as a portion of the ionic salt, the hydroxide, and / or the acid in step (ii). Any suitable technique can be used for isolating the excess and / or leftover ionic salt, hydroxide, and / or acid from the first reaction mixture, non-limiting examples of which include filtering, settling, decanting, pressing, electrowetting, centrifuging, cycloning, hydrocycloning, or any combination thereof.

[0062] Referring now to step (iii), the solid ATH and the first solid fraction are isolated from the first reaction mixture for use in subsequent processing steps. Any suitable technique can be used for isolating the solid ATH and the first solid fraction from the first reaction mixture, non-limiting examples of which include filtering, settling, decanting, pressing, centrifuging, cycloning, hydrocycloning, or any combination thereof. Optionally, after being isolated, the solid ATH and the first solid fraction can be washed in one or more wash cycles with a wash solution that independently can comprise water, an alcohol (e.g., ethanol), or any mixture or combination thereof. Most often, the wash solution comprises (or consists essentially of, or consists of) water.

[0063] The first solid fraction comprises undissolved solids and metals / alloys other than aluminum. If desired, the first solid fraction can be fractionated to isolate (and recover and reuse) at least one metal other than aluminum. The composition of the first solid fraction can vary significantly based on the aluminum purity in the scrap or waste aluminum feed and the source of the scrap or waste aluminum (e.g., aluminum beverage cans versus structural aluminum parts).

[0064] Once isolated, the solid ATH and the first solid fraction is contacted (or reacted) with an aqueous caustic solution in step (iv), thereby forming a second reaction mixture containing dissolved sodium aluminate. Thus, solid ATH is dissolved and sodium aluminate is formed in step (iv). The reaction in step (iv) is endothermic and thus, a portion of the heat / energy produced in step (ii) can be used to heat water or produce steam for improved energy efficiency when forming the second reaction mixture.

[0065] The Na?O concentration of the aqueous caustic solution (or the second reaction mixture) in step (iv) is generally very high, often in the range from 50 to 200 g / L of Na?O (NaOH concertation expressed in terms of Na?O), and more often, the concentration falls within a range from 50 to 150 g / L, from 65 to 120 g / L, from 75 to 100 g / L, from 100 to 180 g / L, from 120 to 170 g / L, or from 130 to 160 g / L, of Na2O. A standard titration procedure is used to determine the Na?O concentration.

[0066] Additionally or alternatively, the NaOH concentration of the aqueous caustic solution (or the second reaction mixture) in step (iv) can be expressed in molarity, and can fall within a range from 1.5 to 7 mol / L in one aspect, or from 1.5 to 5 mol / L in another aspect, from 2 to 4 mol / L in another aspect, from 2.5 to 3.5 mol / L in another aspect, from 3 to 6 mol / L in another aspect, from 3.5 to 5.5 mol / L in yet another aspect, and from 4 to 5 mol / L in still another aspect.

[0067] In an aspect, the aqueous caustic solution contains dissolved sodium aluminate prior to contacting the solid ATH and the first solid fraction, while in another aspect, the aqueous caustic solution contains sodium hydroxide, but does not contain any sodium aluminate.

[0068] Therefore, in some aspects, the molar ratio of Na2O:A12O3 in the reaction mixture in step (iv) can fall within a range from 1.2:1 to 5: 1, although not limited thereto. Illustrative and non-limiting ranges for the molar ratio of Na2O:AhO3 in the second reaction mixture in step (iv) include from 1.2: 1 to 2.5:1, from 1.2:1 to 2:1, from 1.3:1 to 1.8:1, from 1.3:1 to 1.6:1, from 1.35: 1 to 2: 1, from 1.35: 1 to 1.8: 1, from 1.4: 1 to 1.8: 1, or from 1.4: 1 to 1.6: 1, and the like. Advantageously, molar ratios in the range of, for example, from 1.3: 1 to 1.8: 1 or from 1.4: 1 to 1.6: 1 in the final reaction mixture result in higher yields of ATH after subsequent crystallization. As would be readily recognized, the molar ratio changes as the reaction in step (iv) proceeds. For instance, the molar ratio of Na2O:Al2O3in the aqueous caustic solution can fall within a range from 1.5: 1 to 5: 1, from 1.6: 1 to 4: 1, from 1.8: 1 to 3.5:1, or from 2: 1 to 3.2:1, and the like.

[0069] Consistent with aspects of the processes disclosed herein, the aqueous caustic solution (or the second reaction mixture) in step (iv) does not contain solid aluminum trihydrate (ATH), or at least 98 wt. % or at least 99 wt. % of solid ATH has been dissolved. As described herein, the ATH is not precipitated and recovered until a later stage of the process.

[0070] Step (iv) can be performed under a variety of temperature, pressure, and time conditions. For instance, step (iv) can be conducted (or the second reaction mixture can be formed) at a temperature of at least 70 °C. As an illustration, step (iv) can be conducted (or the second reaction mixture can be formed) at a temperature in a range from 50 °C to 200 °C; alternatively, from 100 °C to 200 °C; alternatively, from 50 °C to 165 °C; alternatively, from 110 °C to 165 °C; alternatively, from 125 °C to 165 °C; alternatively, from 70 °C to 140 °C; alternatively, from 90 °C to 140 °C; alternatively, from 90 °C to 130 °C; alternatively, from 95 °C to 110 °C; alternatively, from 70 °C to 108 °C; alternatively, from 90 °C to 108 °C; alternatively, from 80 °C to 105 °C; alternatively, from 80 °C to 100 °C; alternatively, from 90 °C to 100 °C; or alternatively, from 95 °C to 105 °C. These temperature ranges also are meant to encompass circumstances where step (iv) and / or the formation of the second reaction mixture is / are conducted at a series of different temperatures, instead of at a single fixed temperature, wherein at least one temperature falls within the respective ranges.

[0071] The pressure at which step (iv) is conducted (or the second reaction mixture is formed) is not particularly limited, but can be at an elevated pressure (e.g., from 1 bar to 25 bar absolute pressure, from 1.3 bar to 22 bar absolute pressure, or from 2 bar to 10 bar absolute pressure), at atmospheric pressure, or at any suitable sub-atmospheric pressure. In some instances, step (iv) is conducted (or the second reaction mixture is formed) at atmospheric pressure, eliminating the need for pressurized vessels and their associated cost and complexity. Step (iv) can be conducted (or the second reaction mixture can be formed) over a wide range of time periods, and encompasses any time period sufficient for complete reaction of the ATH and the first solid fraction, such as from 5 min to 18 hr, from 5 min to 5 hr, from 5 hr to 2 hr, or from 10 min to 1 hr, but is not limited solely to these time periods. Many factors can influence the appropriate time period for step (iv), such as temperature, pressure, caustic concentration, and the amount of the solid ATH and first solid fraction. If step (iv) of the process is performed continuously, then any average residence time sufficient for complete reaction of the solid ATH and first solid fraction can be utilized.

[0072] Referring now to step (v), a second solid fraction can be removed from the second reaction mixture to form a liquor solution. Any suitable technique can be used for this removing or separating step, non-limiting examples of which include filtering, settling, decanting, pressing, centrifuging, cycloning, hydrocycloning, and the like. Combinations or two or more of these techniques can be used, if desired. Often, the second solid fraction is conveniently removed from the reaction mixture using filtration.

[0073] The second solid fraction in step (v) generally contains undissolved solids and metals / alloys other than aluminum. All or substantially all of the solid ATH present in prior steps of the process should be dissolved and not be present in the second solid fraction. If desired, the second solid fraction can be fractionated to isolate (and recover and reuse) at least one metal other than aluminum. The composition of the second solid fraction can vary significantly based on the aluminum purity in the scrap or waste aluminum feed and the source of the scrap or waste aluminum (e.g., aluminum beverage cans versus structural aluminum parts).

[0074] In step (vi), the liquor solution is seeded with (contacted with) a seed material to precipitate (or crystallize) ATH and form a suspension, also referred to herein as a slurry. Any suitable seed material can be used in step (vi) of the process. In one aspect, the seed material can comprise a bayerite alumina trihydrate, and in another aspect, the seed material can comprise a gibbsite alumina trihydrate, and in still another aspect, the seed material can comprise a mixture or combination of a bayerite alumina trihydrate and a gibbsite alumina trihydrate.

[0075] The seed material generally has a d50 median particle size of from 0.1 to 100 pm, and the seed material can have a unimodal particle size distribution, or alternatively, a bimodal particle size distribution. Other representative ranges for the d50 median particle size of the seed material can include from 0.2 to 50 pm, from 0.4 to 20 pm, from 0.4 to 10 pm, from 0.4 to 5 pm, or from 0.8 to 3 pm, and the like. While not particularly limited, the BET surface area of the seed material ranges from 0.1 to 50 m2 / g, and other suitable ranges for the BET surface area of the seed material include from 0.5 to 40 m2 / g, from 1 to 30 m2 / g, from 0.1 to 10 m2 / g, from 0.2 to 5 m2 / g, from 10 to 20 m2 / g, and from 25 to 35 m2 / g.

[0076] The liquor solution is generally seeded with the seed material at a relatively high (precipitation or crystallization) temperature. While not limited thereto, step (vi) can be conducted (or the suspension can be formed) at a temperature in a range from 40 °C to 90 °C, such as in a range from 45 °C to 85 °C, from 50 to 75 °C, from 55 to 85 °C, from 60 °C to 80 °C, or from 65 °C to 85 °C. The amount of the seed material used is not particularly limited, but often falls in a range from 0.1 to 20 g / L (grams of seed material per liter of the liquor solution). Illustrative and non-limiting ranges for the amount of the seed material, therefore, can include the following ranges: from 0.2 to 10 g / L, from 0.4 to 5 g / L, from 0.4 to 2 g / L, from 5 to 20 g / L, and from 10 to 20 g / L.

[0077] The pressure at which step (vi) is conducted (or the suspension is formed) is not particularly limited, but can be at an elevated pressure (e.g., from 1 bar to 25 bar, from 1.3 bar to 22 bar, or from 2 bar to 10 bar absolute pressure), at atmospheric pressure, or at any suitable sub-atmospheric pressure. In some instances, step (vi) is conducted (or the suspension is formed) at atmospheric pressure, eliminating the need for pressurized vessels and their associated cost and complexity.

[0078] Step (vi) can be conducted (or the suspension can be formed) over a wide range of time periods, such as from 1 hr to 240 hr, from 24 hr to 168 hr, from 48 hr to 120 hr, or from 72 hr to 120 hr, but is not limited solely to these time periods. Many factors can influence the appropriate time period for step (vi), such as temperature, pressure, caustic concentration, and the amount and characteristics of the seed material.

[0079] Referring now to step (vii), a precipitated ATH can be isolated from the suspension and the precipitated ATH can then be washed to form an intermediate ATH product. Any suitable technique can be used to isolate the precipitated ATH from the suspension, non-limiting examples of which include filtering, settling, decanting, pressing, centrifuging, cycloning, hydrocycloning, and the like. Combinations or two or more of these techniques can be used, if desired. Often, the precipitated ATH is conveniently isolated from the suspension using filtration.

[0080] After the precipitated ATH has been isolated, it is generally washed in step (vii), in one or more wash cycles with a wash solution that independently can comprise water, an alcohol (e.g., ethanol), or any mixture or combination thereof. Most often, the wash solution comprises (or consists essentially of, or consists of) water. One objective of the washing step is to remove NaOH and sodium ions from the precipitated ATH to form the intermediate ATH product.

[0081] The intermediate ATH product in step (vii) can have a d50 median particle size of from 0.1 to 150 pm and a BET surface area of from 0.1 to 20 m2 / g, although not limited thereto. In some aspects, the intermediate ATH product can have a d50 particle size of from 0.5 to 120 pm (or from 1 to 10 pm, or from 1 to 5 pm, or from 10 to 100 pm, or from 20 to 50 pm, or from 40 to 80 pm) and a BET surface area of from 0.1 to 1 m2 / g (or from 0.5 to 10 m2 / g, or from 1 to 5 m2 / g, or from 3 to 15 m2 / g, or from 10 to 20 m2 / g).

[0082] Prior to drying the intermediate ATH product in step (ix), and optionally, the process can comprise (viii) milling the intermediate ATH product. The intermediate ATH product can be wet milled, dry milled, or a combination thereof, using any suitable milling or grinding technique. Also optionally, any suitable dispersant or any suitable coating can be applied to the intermediate ATH product to reduce agglomeration or to improve downstream performance of the ATH product, and the dispersant and / or the coating can be applied by re-slurrying the intermediate ATH product (which may be in the form of a filter cake) at high solids (e.g., 50 wt. % or more) in water that contains the appropriate additive (e.g., dispersant or coating).

[0083] The intermediate ATH product is dried in step (ix) to form the precipitated ATH product. Any suitable technique can be used for this drying step, non-limiting examples of which include spray drying, tray drying, flash drying, freeze drying, oven drying, or microwave drying, and the like. Combinations or two or more of these techniques can be used, if desired. Often, the precipitated ATH is conveniently formed by spray drying or flash drying. Any suitable drying conditions can be employed. For example, drying temperatures of the precipitated ATH ranging from 25 °C to 200 °C, from 50 °C to 150 °C, from 70 °C to 120 °C, or from 90 °C to 110 °C, can be used. Consistent with aspects of the present invention, the precipitated alumina trihydrate products described herein (or the precipitated ATH products produced in accordance with any of the processes disclosed herein) can be used in variety of polymer formulations with beneficial performance properties. In an aspect, the precipitated ATH product in step (ix) can have a d50 particle size in a range from 1 to 10 pm, and more often, the d50 particle size of the precipitated ATH product falls within a range from 1.5 to 4.5 pm; alternatively, from 2 to 5 pm; or alternatively, from 2 to 3.5 pm.

[0084] Additionally or alternatively, the precipitated ATH product in step (ix) can have a BET surface area in a range from 1 to 20 m2 / g, from 1 to 10 m2 / g, from 2 to 15 m2 / g, from 2 to 10 m2 / g, from 2 to 5 m2 / g, from 4 to 10 m2 / g, or from 8 to 15 m2 / g, although not limited thereto. Beneficially, the precipitated ATH product can have a total Na?O content in a range from 0.01 to 0.2 wt. %, such as from 0.03 to 0.15 wt. %, from 0.03 to 0.1 wt. %, from 0.04 to 0.15 wt. %, from 0.05 to 0.15 wt. %, or from 0.05 to 0.1 wt. %. Additionally or alternatively, the precipitated ATH product can have a soluble Na?O content in a range from 0.001 to 0.01 wt. %, such as from 0.001 to 0.007 wt. %, from 0.001 to 0.005 wt. %, from 0.002 to 0.01 wt. %, from 0.002 to 0.007 wt. %, or from 0.002 to 0.005 wt. %. These very low sodium contents contribute to less crystal lattice errors and higher purity ATH particles.

[0085] In a further aspect of the processes for producing precipitated ATH, these process optionally can include - after step (vii) - the steps of evaporating water from the suspension to form a concentrated liquor, and then recycling the concentrated liquor for use as a portion of the aqueous caustic solution in step (iv). After the precipitated ATH has been removed, the suspension may be a diluted caustic liquor containing, for instance, NaOH and uncrystallized aluminate in water, often at a Na?O concentration of less than 100 g / L Na2O. Beneficially, at least a portion of the heat / energy produced in step (ii) can be utilized in this step of evaporating water from the suspension after step (vii). Also beneficially, at least a portion of the water evaporated from (or removed from) the suspension can be utilized as a portion of the wash solution in step (vii).

[0086] Referring now to FIG. 1, which illustrates a schematic flow diagram of catalytic process 100 for converting scrap or waste aluminum metal into a precipitated alumina trihydrate (ATH) product consistent with an aspect of the present disclosure. Aluminum metal 102 is introduced into shedder 104 to form a plurality of fragments comprising aluminum.

[0087] The aluminum fragments are contacted with an activating composition comprising gallium and / or indium 106 (e.g., a liquid eutectic mixture of gallium and indium) in order to activate the aluminum and form activated aluminum composition 110. Activated aluminum composition 110 is reacted in reaction chamber 120 with a solution of water 112 and sodium hydroxide (NaOH) 114 to form hydrogen (H2) gas 124, heat / energy 122, and the first reaction mixture. As noted herein, the reaction of aluminum metal with water in reaction chamber 120 is highly exothermic, so heat / energy 122 is produced that can be used elsewhere in process 100. Hydrogen (H2) gas 124 can be captured and stored and subsequently used in a wide range of industrial processes.

[0088] After activated aluminum composition 110 reacts with water, reaction chamber 120 comprises the first reaction mixture. The first reaction mixture can comprise solid ATH, a first solid fraction, the activating composition, aluminum hydroxide oxide (A10(0H)), aluminum oxide (AI2O3), unreacted water, and / or excess and / or leftover NaOH.

[0089] The activating composition in the first reaction mixture can be isolated (e.g., by filtration) and discharged to recovery chamber 126. A portion or all of the recovered activating composition can be utilized to activate additional quantities of aluminum fragments and form another activated aluminum composition 110. Additionally, the excess and / or leftover NaOH can be isolated from the first reaction mixture (e.g., by filtration) and can be recycled and reutilized as a portion of the NaOH 114.

[0090] The solid ATH and the first solid fraction are isolated from the first reaction mixture by filtration 128 to form ATH slurry and first solid fraction 130. Renumbered to indicate its use as a feedstock, ATH slurry and first solid fraction 140 are introduced into digestion vessel 150 that contains an aqueous caustic solution at a very high pH. A typical NaOH concentration is from 3 to 6 M and a typical Na2O concentration is from 100 to 200 g / L of Na2O. All or a portion of heat / energy 122, produced from the aluminum-water reaction, can be used to heat water or produce steam 132 for improved energy efficiency of digestion vessel 150.

[0091] Second reaction mixture 152 containing sodium aluminate is discharged from vessel 150 and filtered 154 to remove second solid fraction 156 and form liquor solution 160. Liquor solution 160 is then contacted with a seed material to initiate precipitation or crystallization 164 of ATH, typically resulting in a suspension of ATH particles in the liquor solution. The suspension is filtered / washed 170 to form solid intermediate ATH 172. Solid intermediate ATH 172 is then treated 174 in one or more operations - for instance, milling, drying, and the like - to form final precipitated ATH product 180.

[0092] Referring back to the step in which the suspension of ATH particles is filtered / washed 170, a diluted liquor fraction is generally produced along with solid intermediate ATH 172. Next, the diluted liquor fraction is concentrated by the removal of water by any suitable technique, but often evaporation unit 184 is used. All or any portion of heat / energy 122, produced from the aluminum-water reaction, can be used to heat water or produce steam 182 for improved energy efficiency of evaporation unit 184.

[0093] Discharged from evaporation unit 184 are water stream 168 and concentrated liquor stream 136. Water stream 168, resulting from water condensate from evaporation unit 184, is utilized as wash water in filter / wash step 170, which forms solid intermediate ATH 172. Concentrated liquor stream 136 is recycled back to digestion vessel 150 to react with additional quantities of ATH slurry and first solid fraction 140, again resulting in second reaction mixture 152.

[0094] POLYMER COMPOSITIONS

[0095] This invention is also directed to, and encompasses, any compositions, formulations, composites, and articles of manufacture that contain any of the precipitated ATH products disclosed herein. In a particular aspect of this invention, a polymer composition is disclosed, and in this aspect, the polymer composition can comprise any suitable polymer (one or more than one) and any of the precipitated ATH products disclosed herein (or the precipitated ATH products produced by any process described herein).

[0096] In one aspect, the polymer in the polymer composition can comprise a thermoplastic polymer, while in another aspect, the polymer can comprise a thermoset polymer. In another aspect, the polymer can comprise, either singly or in any combination, an ethylene-based polymer (e.g., a polyethylene, an ethylene homopolymer, or an ethylene-based copolymer, such as an ethylene / a-olefin copolymer, and the like), a propylene-based polymer (e.g., a polypropylene, a propylene homopolymer, a propylene-based copolymer, and the like), and / or an ethylene / vinyl acetate (EVA) copolymer.

[0097] While not being limited thereto, the amount of the precipitated ATH product in the polymer composition often can fall in a weight ratio range of polymerATH from 100: 1 to 10:90. Illustrative and non-limiting ranges for the weight ratio of polymerATH in the polymer composition, therefore, can include the following ranges: from 100: 1 to 80:20, from 90:10 to 25:75, from 90: 10 to 50:50, or from 90:10 to 75:25.

[0098] Optionally, the polymer composition can further comprise any suitable additive, non-limiting examples of which can include a stabilizer, a lubricant, a filler, a colorant, and the like, as well as combinations thereof.

[0099] Articles of manufacture can be formed from and / or can comprise any of the polymer compositions described herein. For example, in a particular aspect, the article of manufacture can comprise a wire or cable.

[0100] EXAMPLES

[0101] The invention is further illustrated by the following examples, which are not to be construed in any way as imposing limitations to the scope of this invention. Various other aspects, modifications, and equivalents thereof which, after reading the description herein, may suggest themselves to one of ordinary skill in the art without departing from the spirit of the present invention or the scope of the appended claims.

[0102] The d50 particle size, or median particle size, refers to the diameter of volume equivalent spheres for which 50% of the sample has a smaller diameter and 50% of the sample has a larger diameter. Particle size measurements (inclusive of dlO, d50, and d90) were determined by laser diffraction using a LS 13 320 laser diffractometer from Beckman Coulter Inc., in accordance with ISO 13320. A diluted dispersant solution of polyphosphates in deionized water (see below) was introduced into the measurement equipment. A small sample was mixed externally with 20 mL of this dispersant solution and treated with ultrasound of 200 W for 2 min. A background measurement was taken. The pre-dispersed sample suspension was slowly added to the equipment until a sufficient obscuration, as defined by the software and the manufacturer, was achieved in the optical device for laser diffraction. The amount needed is dependent on the particle size and material type and may therefore vary between samples. For data evaluation, the Mie theory was used. The required physical data of ATH is the refractive index of 1.58, and for the dispersant solution, the refractive index is 1.333.

[0103] The water / dispersant solution was mixed by first preparing a concentrate from 500 g Calgon N, available from Julius Hoesch GmbH & Co. KG, with 3 liters of Solutrix A40, 40%, available from BASF. This solution was made up to 10 L with deionized water. Then, 100 mL of this original 10 L was in turn diluted further to 10 L with deionized water, and this final solution was used as the water-dispersant solution described above.

[0104] BET surface areas were determined using the BET nitrogen adsorption method of Brunauer et al., J. Am. Chem. Soc., 60, 309 (1938) in accordance with DIN-66132 using Micromeritics Gemini V and Gemini VII instruments.

[0105] The total Na?O content (wt. %) and the soluble Na?O content (wt. %) are determined by flame photometry. For the measurement of the total Na?O content, predried ATH is treated with concentrated sulfuric acid and heated above the boiling point until all acid has evaporated. The remaining sulfate salts are then completely dissolved in deionized water. The Na?O content of this solution is determined with a flame photometer M410C from Sherwood. The solution is mixed into a gas flame and the intensity of light at the typical Na wavelength of 589 nm is analyzed versus a calibration standard. For the measurement of the soluble Na?O content, pre-dried ATH is treated with deionized water at 95 °C for 45 min, then cooled. The Na?O content of this solution is determined using the flame photometer as described for the total Na?O content.

[0106] X-ray powder fluorescence (XRF) was performed on a S4 Explorer instrument from Bruker AXS. The sample was placed in a high-energy X-ray beam which stimulates X-ray emission from the sample. The frequency of the emitted radiation is specific for the elements in the sample, independent of the sample phase composition. Evaluation of the X-ray frequencies and intensity therefore yields information about the elementary composition of the sample, both qualitatively and quantitatively. Only elements above an atomic number of 9 (fluorine) can be detected, as lighter elements require an even higher activation energy.

[0107] X-Ray powder diffraction (XRD) was performed on a D2 Phaser from Bruker AXS, equipped with Bragg-Brentano focusing, applying a copper anode with a nickel filter for monochromatization. The sample was placed in a monochromatized X-ray beam which results in diffraction signals. Those signals can be interpreted and compared to literature data to analyze the phase composition of a crystalline sample. A mixture will give all diffraction patterns of all crystalline phases present. Amorphous or noncrystalline materials will not show diffraction signals in XRD.

[0108] EXAMPLE 1

[0109] A starting aqueous solution was prepared in a flask equipped with a reflux condenser at room temperature and ambient pressure. This 60 g aqueous solution contained 155 g / L Na?O and 82.3 g / L AI2O3, and the molar ratio of ISfeCkAhCL was 3.1 :1. Approximately 4.66 g of water was then added to reach a concentration of 149.2 g / L Na?O and 78.9 g / L AI2O3 (the molar ratio was unchanged).

[0110] As a representative aluminum metal feedstock, standard kitchen aluminum foil (2.36 g) was added to the flask. Within a few minutes, the temperature increased dramatically and the reaction mixture eventually began boiling. The hydrogen gas was not collected during this experiment. After 16 min, the aluminum foil was completely reacted. The final reaction mixture contained 151 g / L Na2O and 168 g / L AI2O3, and the molar ratio of ISfeCkAhCL was 1.47. Some solids were present in the reaction mixture, likely the result of copper-based alloys or compounds, as well as carbonaceous materials, that were minor components of the aluminum foil. After cooling, the reaction mixture was filtered to remove the solids, resulting in a clear liquor solution.

[0111] EXAMPLE 2

[0112] The experiments in Examples 2-6 were conducted in a 3 -neck 2-L glass flask equipped in the middle with a reflux condenser cooled with tap water, and on the side necks a thermometer and a stopper which can be removed to add the aluminum sample. The flask was placed in a heated water bath on top of a magnetic stirrer plate. The water bath served to heat the liquor in the flask to the starting temperature. For each experiment, nominally 0.5 L of the starting liquor (orNaOH solution in some examples) was heated to the required temperature. The indicated amount of an aluminum sample was added and the reaction started immediately, releasing H2 gas. In Example 2, high purity aluminum granules were used (99.2 wt. % Al per XRF), the compositional breakdown of which in summarized in Table A. Granule size was in the range of approximately 0.5 cm. For Examples 2A-2D, 0.5 L of a Bayer process liquor containing dissolved sodium aluminate was heated to 67-91 °C, as shown in Table B, and the Al granules were added. The amount (g) of Al added was calculated to result in the same target molar ratio of ISfeCkAhCh of approximately 1.35 after 120 min. The composition of the starting liquor and samples of the reaction mixture after 20 min, 60 min, and 120 min were analyzed, and the results are summarized in Table B.

[0113] Examples 2A-2B were produced at very low Na?O concentrations. Thus, the aluminum dissolution rates were slow and the absolute concentrations after 120 min of reaction were too low for suitable ATH production.

[0114] The amount of EE released (g) and heat energy released (watt-hr, Wh) in Table B were calculated based on known aluminum reactions and the data at 120 min. The laboratory set-up was not equipped to measure the heat released from the reaction, but generally, the initial reaction led to a strong and fast increase of the temperature both in the flask and in the water bath. For instance, the water bath was heated in Example 2D to 70 °C by the magnetic stirrer and heating plate below it. Heating was stopped before the addition of the Al metal. The mass of the water in the water bath was about 2 L, so much larger than the flask volume. The liquor in the flask was at 67 °C when the Al metal was added, then temperature rose sharply to 91 °C, all the while also releasing heat to the surrounding water bath, the temperature of which rose to 78 °C. Not taken into account here is the heat that is lost via the H2 gas release and the water vapor being cooled by the reflux condenser. In sum, in the batchwise reaction, the heat release was highest at the start and then became slower, while all the time, heat was also exchanged with the surroundings, which led to cooling. Most of the energy / heat from the reaction in the flask was moderated by the water in the water bath.

[0115] Table A. XRF analysis (wt. %) of the high purity Al granules of Example 2. Table B. Summary of Examples 2A-2D

[0116] EXAMPLE 3

[0117] In Example 3, the high purity aluminum granules (99.2 wt. % Al per XRF) of Example 2 were used. As shown in Table C, for Examples 3A-3C, 0.5 L of a Bayer process liquor containing dissolved sodium aluminate was used, and for Examples 3D- 3F, 0.5 L of a NaOH solution was used (no sodium aluminate). After heating to the respective temperatures shown in Table C, the same amount of the Al granules were added (20 g) to determine the impact of different liquor concentrations.

[0118] The composition of the starting liquor and samples of the reaction mixture after 20 min and 60 min were analyzed, and the results are summarized in Table C. Examples 3 A and 3D utilized initial Na?O concentrations of approximately 9 g / L, resulting in a much slower reaction. Further, in both cases, ATH started to precipitate after about 20 min. This explains the decreasing value for dissolved ATH (dissolved Al is no longer equal to reacted Al, because some of the reacted Al is no longer in solution). At this concentration, ATH will start to precipitate during the reaction, significantly limiting the amount of Al to be dissolved, making operating at these conditions completely impractical. The precipitated ATH is not in a form to be directly used as a flame retardant or any other suitable end-use application. In principle, it would also be mixed with the residue of the alloy or scrap, as shown in the following examples, rendering it unusable.

[0119] For Examples 3B-3C and 3E-3F, almost all of the aluminum was dissolved after 60 min. Since there is no starting concentration of sodium aluminate in Examples 3E- 3F, the concentration of Al in pure NaOH was lower after the same time, and more Al was needed to reach the same concentration range. Note the significantly lower molar ratios of Na2O:AhO3 for Examples 3B-3C as compared to 3E-3F after both 20 min and 60 min. At the higher ratios of Na2O:AhO3 for Examples 3E-3F when using NaOH as the starting caustic solution (e.g., outside of the range of 1.3 : 1 to 1.8: 1 in the final reaction mixture), aluminum is wasted in the form of dissolved sodium aluminate and there is a poor yield of ATH after subsequent crystallization.

[0120] Table C. Summary of Examples 3A-3F

[0121] EXAMPLE 4

[0122] In Example 4, aluminum alloys were used (90+ wt. % Al per XRF). Table D summarizes the compositional breakdown of Alloy 1 (Al / Cu / Pb / Mn alloy, used in Examples 4A-4B) and Alloy 2 (Al / Mg / Si alloy, used in Examples 4C-4D). For these examples, 0.5 L of a Bayer process liquor containing dissolved sodium aluminate was heated to about 80 °C, as shown in Table E, and the Al samples of approximately the same weight were added (25-26 g). The overall surface area of the Al alloy pieces varied between 38 cm2and 71 cm2. The pieces overall had lower surface area and were much larger than the granules used in Examples 2-3. The aluminum pieces ranged from about 0.6 cm to 2 cm in length.

[0123] The composition of the starting liquor and samples of the reaction mixture after 20 min, 60 min, and 120 min were analyzed, and the results are summarized in Table E. There were only minor differences in reaction rate between the alloys, but there were significant differences in reaction rate based on surface area, for instance, compared to Examples 2-3. The percentage of Al dissolved was calculated versus the mass of Al content of the added alloy, not on the mass of the alloy.

[0124] Apart from undissolved Al, in these examples, there was also are up to ~10 wt. % of insoluble elements in the alloy that remained undissolved after 120 min. This was different from Examples 2-3, where only a very minor amount of residue was found. Nonetheless, despite the large particle size of the aluminum starting material and residue in the reaction mixture, the overall target liquor concentrations for the production of ATH were unexpectedly reached, for instance, molar ratios of Na2O:AhO3 for Examples 4A- 4D in the 1.4: 1 to 1.8: 1 range after 120 min.

[0125] The residue compositions were analyzed by XRF and are summarized in Table F (alloy 1) and Table G (alloy 2). In general, the composition of the respective residue was consistent with the composition of the alloy. For alloy 2 (Table G), there was a significant amount of aluminum, and it is possible that the sodium came from liquor, while it appears that most of the silicon was dissolved in the liquor. The values for the alloy and the residue do not correlate exactly, as the information about phase composition is missing, and the amount of oxide, hydroxide, or possibly carbonate ions is unknown. The sodium content suggests that also some insoluble sodium salts have formed. XRD (x-ray diffraction) of the residue to investigate phase composition showed almost no diffraction intensity, which means that the residue was not crystalline, but was amorphous per XRD.

[0126] For alloy 1 (Table F), the overall correlation between alloy and residue was better.

[0127] While the percentage of aluminum in the alloy was reduced by a factor of 10 in the residue, other metals increased by a factor of about 10. Again, it appears that most of the silicon was dissolved in the liquor. Also, as above, the residue was amorphous per XRD, so no information on the percentage of oxides, hydroxides, or carbonates was obtained.

[0128] Table D. XRF analysis (wt. %) of the Al alloys of Example 4.

[0129] Table E. Summary of Examples 4A-4D Table F. XRF analysis (wt. %) of Alloy 1 and the Residue of Alloy 1 of Example 4 Table G. XRF analysis (wt. %) of Alloy 2 and the Residue of Alloy 2 of Example 4. EXAMPLE 5

[0130] In Example 5, aluminum scrap pieces from two different waste disposal facilities were used. The scrap samples were non-homogenous, containing small particles of different colors and glass-like particles. Therefore, analytical testing (e.g., XRF) of the scrap compositions is not representative of the entirety of the scrap sample, since the sample amount for such analytical testing is small (a few mg). Therefore, analytical testing was repeated; differences in compositional breakdown were expected due to the non-homogeneity of the scrap samples. Table H summarizes the results of several XRF analytical tests on scrap sample 1 and scrap sample 2.

[0131] Due to sample non-homogeneity, average Al contents were used. Examples 5 A- 5B used scrap sample 1 with different size ranges: 5-10 mm range for Example 5A, and 10-20 mm range of Example 5B. Examples 5C-5D used scrap sample 2 with different size ranges: 5-10 mm range for Example 5C, and 10-20 mm range for Example 5D.

[0132] For these examples, 0.5 L of a Bayer process liquor containing dissolved sodium aluminate was heated to 81 °C, as shown in Table I, and the Al scrap samples of different amounts were added. The amount of scrap was based on the average purity and targeted a molar ratio of ISfeCkAhCh of 1.47. In some experiments, this was not reached within 120 min, likely due to the fact that the Al purity was overestimated, and a longer reaction time would be needed.

[0133] After each experiment, a black non-crystalline (XRD amorphous) residue was filtered from the reaction mixture. The XRF compositions shown in Table J included many different elements / metals, but were generally consistent with the scrap sample analytical results in Table H. Since the main component of aluminum is significantly reduced in the residues, other elements / metals can be found in the residue that were not picked up in the original scrap samples. While there is still aluminum in the residue, it appears to be unreacted aluminum, since there was surprisingly no ATH found in the residue (ATH would give peaks in XRD).

[0134] Table H. XRF analysis (wt. %) of the Al scrap samples of Example 5.

[0135] Table I. Summary of Examples 5A-5D Table J. XRF analysis (wt. %) of the Residues of Examples 5A-5D.

[0136] EXAMPLE 6

[0137] For Example 6, 1 L of a Bayer process liquor containing dissolved sodium aluminate was heated to 111 °C, which was the boiling point of this liquor, and Al scrap sample 1 from Example 5 was added. The reaction time was 180 min. Table K summarizes the results of Example 6. The final molar ratio of ISfeChAhCh in the reaction mixture was 1.43, and over 93 wt. % of the pure aluminum in the scrap sample was dissolved.

[0138] After reaction completion, a residue was filtered from the reaction mixture, and the compositional breakdown of the residue is shown in Table L. The materials and relative amounts in the residue composition of Example 6 are in reasonable agreement with Examples 5A-5B in Table J, particularly considering the non-homogeneity of the scrap samples. After the solid residue was removed from the reaction mixture, 0.96 L of the resulting liquor solution was used to produce a precipitated ATH product. At a temperature of 65 °C, approximately 0.5 g of an ATH seed material, containing gibbsite and bayerite, with a d50 of 0.5-2 pm and a BET surface area of 5-30 m2 / g was added to the liquor solution. After 67 hr of crystallization time, the resulting solid ATH was filtered from the liquor, and washed with deionized water to form an intermediate ATH product. After drying, the precipitated ATH product had a d50 average particle size of 3.6 pm and a BET surface area of 1.7 m2 / g. The yield was 112 g / L of ATH.

[0139] In sum, Examples 1-6 demonstrate that regardless of the aluminum source - pure aluminum, aluminum alloy, or scrap aluminum - target concentrations of Na?O and AI2O3 and target molar ratios of ISfedAhCE in the reaction mixture were achieved to result in suitable ATH production. Particle size and surface area of the aluminum source impacted reaction rate, but a wide range of sizes and shapes were nonetheless processed successfully. Similarly, aluminum sources with aluminum purities ranging from under 40 wt. % to over 99 wt. % were also processed successfully, with more solid residue (e.g., the mixture of undissolved metal s / elements) resulting from the lower purity aluminum sources.

[0140] Table K. Summary of Example 6 Table L. XRF analysis (wt. %) of the Residue of Example 6.

[0141] The invention is described above with reference to numerous aspects and specific examples. Many variations will suggest themselves to those skilled in the art in light of the above detailed description. All such obvious variations are within the full intended scope of the appended claims. Other aspects of the invention can include, but are not limited to, the following (aspects are described as “comprising” but, alternatively, can “consist essentially of’ or “consist of’):

[0142] Aspect 1. A process for producing a precipitated alumina trihydrate (ATH) product from aluminum metal, the process comprising (i) contacting the aluminum metal with an activating composition comprising gallium and / or indium to form an activated aluminum composition, (ii) reacting the activated aluminum composition with water and an ionic salt, a hydroxide, and / or an acid to form hydrogen (H2) gas and a first reaction mixture comprising solid ATH and a first solid fraction, (iii) isolating the solid ATH and the first solid fraction from the first reaction mixture, (iv) contacting the solid ATH and the first solid fraction with an aqueous caustic solution to form a second reaction mixture containing dissolved sodium aluminate, (v) removing a second solid fraction from the second reaction mixture to form a liquor solution, (vi) seeding the liquor solution with a seed material to precipitate ATH and form a suspension, (vii) isolating precipitated ATH from the suspension and washing the precipitated ATH to form an intermediate ATH product, (viii) optionally, milling the intermediate ATH product, and (ix) drying the intermediate ATH product to form the precipitated ATH product.

[0143] Aspect 2. The process defined in aspect 1, wherein the aluminum metal is in any shape or configuration, such as sheet like, spherical, oblong, or irregular.

[0144] Aspect 3. The process defined in aspect 1 or 2, wherein an average particle size or an average thickness of the aluminum metal is in a range from 0.1 to 100 mm, from 1 to 100 mm, from 5 to 100 mm, from 0.1 to 30 mm, from 1 to 30 mm, 3 to 30 mm, from 5 to 30 mm, from 0.1 to 10 mm, from 1 to 10 mm, or from 3 to 10 mm; and / or wherein a purity of the aluminum metal is at least 30 wt. %, at least 40 wt. %, at least 50 wt. %, at least 60 wt. %, at least 70 wt. %, at least 80 wt. %, at least 90 wt. %, at least 92 wt. %, at least 95 wt. %, at least 98 wt. %, or at least 99 wt. % aluminum.

[0145] Aspect 4. The process defined in any one of aspects 1-3, wherein the aluminum metal is an aluminum alloy comprising silicon, magnesium, manganese, copper, zinc, tin, or any combination thereof.

[0146] Aspect 5. The process defined in aspect 4, wherein an amount of aluminum in the aluminum alloy is greater than or equal to 40 wt. %, greater than or equal to 50 wt. %, greater than or equal to 60 wt. %, greater than or equal to 70 wt. %, greater than or equal to 80 wt. %, greater than or equal to 90 wt. %, greater than or equal to 95 wt. %, greater than or equal to 99 wt. %, or greater than or equal to 99.99 wt. %, based on the total weight of the aluminum alloy.

[0147] Aspect 6. The process defined in any one of aspects 1-5, wherein a polymeric coating is present on the surface of the aluminum metal.

[0148] Aspect 7. The process defined in aspect 6, wherein the polymeric coating comprises a polyethylene, a polypropylene, a polyester, a polystyrene, an acrylic resin, a polyvinyl, a phenolic resin, an epoxy resin, or any combination thereof.

[0149] Aspect 8. The process defined in any one of aspects 1-7, wherein prior to step (i), the aluminum metal is processed in a comminution device to reduce an average particle size or an average thickness of the aluminum metal. Aspect 9. The process defined in aspect 8, wherein the comminution device is an impact crusher, a hammer mill, a jet mill, a roll mill, a roll crusher, a jaw crusher, an ultrasonic device, or a combination thereof.

[0150] Aspect 10. The process defined in any one of aspects 1-9, wherein prior to step (i), the aluminum metal is shredded or fragmented to form aluminum metal fragments.

[0151] Aspect 11. The process defined in aspect 10, wherein the aluminum metal fragments are compressed together in a die with a press to form a pellet having any suitable thickness, diameter, and / or width.

[0152] Aspect 12. The process defined in any one of aspects 1-11, wherein the activating composition in step (i) is a liquid eutectic mixture (i.e., a mixture that would remain in liquid form at room temperature) of gallium and indium or a close-to eutectic mixture (i.e., a mixture that would remain in a liquid and / or semi-liquid form at room temperature) of gallium and indium.

[0153] Aspect 13. The process defined in any one of aspects 1-12, wherein the activating composition contains an amount of gallium in a range from 70 to 80 wt. % gallium, based on the total weight of the activating composition.

[0154] Aspect 14. The process defined in any one of aspects 1-13, wherein the activating composition contains an amount of indium in a range from 20 to 30 wt. % indium, based on the total weight of the activating composition.

[0155] Aspect 15. The process defined in any one of aspects 1-14, wherein contacting the aluminum metal with the activating composition comprising gallium and / or indium in step (i) comprises applying (e.g., painting) a coating of the activating composition onto the aluminum metal to form the activated aluminum composition.

[0156] Aspect 16. The process defined in any one of aspects 1-14, wherein contacting the aluminum metal with the activating composition comprising gallium and / or indium in step (i) comprises melting / mixing the aluminum metal and the activating composition together to form an alloy mixture and solidifying the alloy mixture to form the activated aluminum composition.

[0157] Aspect 17. The process defined in any one of aspects 1-16, wherein step (i) is conducted (or the activated aluminum composition is formed) at a temperature in a range from 100 °C to 200 °C, from 110 °C to 190 °C, from 120 °C to 180 °C, from 130 °C to 170 °C, or from 140 °C to 160 °C. Aspect 18. The process defined in any one of aspects 1-17, wherein step (i) is conducted for (or the activated aluminum composition is formed in) a time period in a range from 1 hr to 240 hr, from 24 hr to 168 hr, from 48 hr to 120 hr, or from 72 hr to 120 hr.

[0158] Aspect 19. The process defined in any one of aspects 1-18, wherein the aluminum metal in the activated aluminum composition in step (i) is more reactive towards water than aluminum metal that has not been contacted with the activating composition comprising gallium and / or indium.

[0159] Aspect 20. The process defined in any one of aspects 1-19, further comprising, before step (ii), milling the activated aluminum composition to form activated aluminum particles.

[0160] Aspect 21. The process defined in aspect 20, wherein the activated aluminum particles are suspended in a carrier fluid to form a slurry and / or are in a solid form (e.g., a powder).

[0161] Aspect 22. The process defined in any one of aspects 1-21, wherein the hydrogen (H2) gas formed in step (ii) is captured or collected.

[0162] Aspect 23. The process defined in any one of aspects 1-22, wherein step (ii) produces heat / energy.

[0163] Aspect 24. The process defined in any one of aspects 1-23, wherein step (ii) produces heat / energy, and the heat / energy is converted to steam.

[0164] Aspect 25. The process defined in any one of aspects 1-24, wherein the activated aluminum composition is reacted with water and the hydroxide in step (ii).

[0165] Aspect 26. The process defined in any one of aspects 1-25, wherein the hydroxide is sodium hydroxide, potassium hydroxide, calcium hydroxide, and / or magnesium hydroxide.

[0166] Aspect 27. The process defined in any one of aspects 1-26, wherein the ionic salt, the hydroxide, and / or the acid in step (ii) is dissolved and / or suspended in the water.

[0167] Aspect 28. The process defined in aspect 27, wherein the concentration of the ionic salt, the hydroxide, and / or the acid in the water is from 0.1 M to 10 M, from 1 M to 8 M, or from 4 M to 6 M.

[0168] Aspect 29. The process defined in any one of aspects 1-28, wherein the ionic salt, the hydroxide, and / or the acid in step (ii) is in a solid form (e.g., a powder). Aspect 30. The process defined in any one of aspects 1-29, wherein the first solid fraction comprises undissolved solids and metals / alloys other than aluminum.

[0169] Aspect 31. The process defined in any one of aspects 1-30, wherein the first reaction mixture in step (ii) further comprises the activating composition comprising gallium and / or indium, aluminum hydroxide oxide (A10(0H)), aluminum oxide (AI2O3), unreacted water, and / or excess and / or leftover ionic salt, hydroxide, and / or acid.

[0170] Aspect 32. The process defined in any one of aspects 1-31, wherein the first reaction mixture at the end of step (ii) comprises water in an amount from 1 wt. % to 25 wt. %, from 5 wt. % to 20 wt. %, or from 10 wt. % to 15 wt. %, based on the total weight of the first reaction mixture.

[0171] Aspect 33. The process defined in any one of aspects 1-32, further comprising after step (ii), isolating the activating composition comprising gallium and / or indium from the first reaction mixture and recycling the activating composition for use as a portion of the activating composition in step (i).

[0172] Aspect 34. The process defined in aspect 33, wherein isolating the activating composition comprising gallium and / or indium from the first reaction mixture comprises filtering, settling, decanting, pressing, electrowetting, centrifuging, cycloning, hydrocycloning, or any combination thereof.

[0173] Aspect 35. The process defined in aspect 33 or 34, wherein from 96 wt. % to 100 wt. %, from 96 wt. % to 99 wt. %, or from 98 wt. % to 99.9 wt. % of the activating composition is isolated from the first reaction mixture.

[0174] Aspect 36. The process defined in any one of aspects 1-35, further comprising after step (ii), isolating the excess and / or leftover ionic salt, hydroxide, and / or acid from the first reaction mixture and recycling the excess and / or leftover ionic salt, hydroxide, and / or acid for use as a portion of the ionic salt, the hydroxide, and / or the acid in step (ii).

[0175] Aspect 37. The process defined in aspect 36, wherein isolating the excess and / or leftover ionic salt, hydroxide, and / or acid from the first reaction mixture comprises filtering, settling, decanting, pressing, electrowetting, centrifuging, cycloning, hydrocycloning, or any combination thereof.

[0176] Aspect 38. The process defined in any one of aspects 1-37, wherein isolating the solid ATH and the first solid fraction from the first reaction mixture in step (iii) comprises filtering, settling, decanting, pressing, centrifuging, cycloning, hydrocycloning, or any combination thereof.

[0177] Aspect 39. The process defined in any one of aspects 1-38, wherein at least a portion of the heat / energy produced in step (ii) is utilized in step (iv).

[0178] Aspect 40. The process defined in any one of aspects 1-39, wherein a Na2O concentration of the aqueous caustic solution (or the second reaction mixture) in step (iv) is in a range from 50 to 200 g / L, from 50 to 150 g / L, from 65 to 120 g / L, from 75 to 100 g / L, from 100 to 180 g / L, from 120 to 170 g / L, or from 130 to 160 g / L, of Na2O (NaOH concertation expressed in terms of Na2O).

[0179] Aspect 41. The process defined in any one of aspects 1-40, wherein a NaOH concentration of the aqueous caustic solution (or the second reaction mixture) in step (iv) is in a range from 1.5 to 7 mol / L, from 1.5 to 5 mol / L, from 2 to 4 mol / L, from 2.5 to 3.5 mol / L, from 3 to 6 mol / L, from 3.5 to 5.5 mol / L, or from 4 to 5 mol / L.

[0180] Aspect 42. The process defined in any one of aspects 1-41, wherein a molar ratio of Na2O:Al2O3in the second reaction mixture in step (iv) is in a range from 1.2: 1 to 5: 1, from 1.2: 1 to 2.5: 1, from 1.2: 1 to 2: l, from 1.3: 1 to 1.8: 1, from 1.3: 1 to 1.6: 1, from 1.35: 1 to 2: 1, from 1.35: 1 to 1.8: 1, from 1.4: 1 to 1.8: 1, or from 1.4: 1 to 1.6: 1.

[0181] Aspect 43. The process defined in any one of aspects 1-42, wherein step (iv) is conducted (or the second reaction mixture is formed) at a temperature of at least 70 °C.

[0182] Aspect 44. The process defined in any one of aspects 1-43, wherein step (iv) is conducted (or the second reaction mixture is formed) at a temperature in a range from 50 °C to 200 °C, from 100 °C to 200 °C, from 50 °C to 165 °C, from 110 °C to 165 °C, from 125 °C to 165 °C, from 70 °C to 140 °C, from 90 °C to 140 °C, from 90 °C to 130 °C, from 95 °C to 110 °C, from 70 °C to 108 °C, from 90 °C to 108 °C, from 80 °C to 105 °C, from 80 °C to 100 °C, from 90 °C to 100 °C, or from 95 °C to 105 °C.

[0183] Aspect 45. The process defined in any one of aspects 1-44, wherein step (iv) is conducted (or the second reaction mixture is formed) at ambient or atmospheric pressure.

[0184] Aspect 46. The process defined in any one of aspects 1-44, wherein step (iv) is conducted (or the second reaction mixture is formed) at a pressure in a range from 1 bar to 25 bar, from 1.3 bar to 22 bar, or from 2 bar to 10 bar absolute pressure. Aspect 47. The process defined in any one of aspects 1-46, wherein step (iv) is conducted for (or the second reaction mixture is formed in) a time period in a range from 5 min to 18 hr, from 5 min to 5 hr, from 5 hr to 2 hr, or from 10 min to 1 hr.

[0185] Aspect 48. The process defined in any one of aspects 1-47, wherein the aqueous caustic solution (or the second reaction mixture) does not contain solid aluminum trihydrate (ATH), or the aqueous caustic solution contains dissolved sodium aluminate, or both.

[0186] Aspect 49. The process defined in any one of aspects 1-48, wherein removing the second solid fraction in step (v) comprises filtering, settling, decanting, pressing, centrifuging, cycloning, hydrocycloning, or any combination thereof.

[0187] Aspect 50. The process defined in any one of aspects 1-49, wherein the second solid fraction contains undissolved solids and other metals / alloys.

[0188] Aspect 51. The process defined in any one of aspects 1-50, wherein step (vi) is conducted (or the suspension is formed) at a temperature in a range from 40 °C to 90 °C, from 45 °C to 85 °C, from 50 to 75 °C, from 55 to 85 °C, from 60 °C to 80 °C, or from 65 °C to 85 °C.

[0189] Aspect 52. The process defined in any one of aspects 1-51, wherein step (vi) is conducted (or the suspension is formed) at ambient or atmospheric pressure.

[0190] Aspect 53. The process defined in any one of aspects 1-51, wherein step (vi) is conducted (or the suspension is formed) at a pressure in a range from 1 bar to 25 bar, from 1.3 bar to 22 bar, or from 2 bar to 10 bar absolute pressure.

[0191] Aspect 54. The process defined in any one of aspects 1-53, wherein step (vi) is conducted for (or the suspension is formed in) a time period in a range from 1 hr to 240 hr, from 24 hr to 168 hr, from 48 hr to 120 hr, or from 72 hr to 120 hr.

[0192] Aspect 55. The process defined in any one of aspects 1-54, wherein the seed material comprises bayerite alumina trihydrate, gibbsite alumina trihydrate, or a combination thereof.

[0193] Aspect 56. The process defined in any one of aspects 1-55, wherein the seed material has a d50 median particle size in a range from 0.1 to 100 pm, from 0.2 to 50 pm, from 0.4 to 20 pm, from 0.4 to 10 pm, from 0.4 to 5 pm, or from 0.8 to 3 pm.

[0194] Aspect 57. The process defined in any one of aspects 1-56, wherein the seed material has a unimodal particle size distribution or a bimodal particle size distribution. Aspect 58. The process defined in any one of aspects 1-57, wherein the seed material has a BET surface area in a range from 0.1 to 50 m2 / g, from 0.5 to 40 m2 / g, froml to 30 m2 / g, from 0.1 to 10 m2 / g, from 0.2 to 5 m2 / g, from 10 to 20 m2 / g, or from 25 to 35 m2 / g.

[0195] Aspect 59. The process defined in any one of aspects 1-58, wherein an amount of the seed material per liter of the liquor solution is in a range from 0.1 to 20 g / L, from 0.2 to 10 g / L, from 0.4 to 5 g / L, from 0.4 to 2 g / L, from 5 to 20 g / L, or from 10 to 20 g / L.

[0196] Aspect 60. The process defined in any one of aspects 1-59, wherein isolating the precipitated ATH from the suspension in step (vii) comprises filtering, settling, decanting, pressing, centrifuging, cycloning, hydrocycloning, or any combination thereof.

[0197] Aspect 61. The process defined in any one of aspects 1-60, wherein washing the precipitated ATH in step (vii) is performed in one or more wash cycles with a wash solution comprising water, an alcohol (e.g., ethanol), or a mixture thereof.

[0198] Aspect 62. The process defined in any one of aspects 1-61, wherein the intermediate ATH product in step (vii) has a d50 particle size in a range from 0.1 to 150 pm, from 0.5 to 120 pm, from 1 to 10 pm, from 1 to 5 pm, from 10 to 100 pm, from 20 to 50 pm, or from 40 to 80 pm.

[0199] Aspect 63. The process defined in any one of aspects 1-62, wherein the intermediate ATH product in step (vii) has a BET surface area of from 0.1 to 20 m2 / g, from 0.1 to 1 m2 / g, from 0.5 to 10 m2 / g, from 1 to 5 m2 / g, from 3 to 15 m2 / g, or from 10 to 20 m2 / g.

[0200] Aspect 64. The process defined in any one of aspects 1-63, wherein the process comprises (viii) milling the intermediate ATH product.

[0201] Aspect 65. The process defined in any one of aspects 1-64, wherein milling in step (viii) comprises dry milling the intermediate ATH product.

[0202] Aspect 66. The process defined in any one of aspects 1-64, wherein milling in step (viii) comprises wet milling a slurry of the intermediate ATH product in water.

[0203] Aspect 67. The process defined in any one of aspects 1-66, wherein drying the intermediate ATH product in step (ix) is conducted at a temperature in a range from 25 °C to 200 °C, from 50 °C to 150 °C, from 70 °C to 120 °C, or from 90 °C to 110 °C. Aspect 68. The process defined in any one of aspects 1-67, wherein drying the intermediate ATH product in step (ix) comprises spray drying, tray drying, flash drying, freeze drying, oven drying, or microwave drying.

[0204] Aspect 69. The process defined in any one of aspects 1-68, wherein the precipitated ATH product in step (ix) has a d50 particle size in a range from 1 to 10 pm, from 1.5 to 4.5 pm, from 2 to 5 pm, or from 2 to 3.5 pm.

[0205] Aspect 70. The process defined in any one of aspects 1-69, wherein the precipitated ATH product in step (ix) has a BET surface area in a range from 1 to 20 m2 / g, from 1 to 10 m2 / g, from 2 to 15 m2 / g, from 2 to 10 m2 / g, from 2 to 5 m2 / g, from 4 to 10 m2 / g, or from 8 to 15 m2 / g.

[0206] Aspect 71. The process defined in any one of aspects 1-70, wherein the precipitated ATH product in step (ix) has a total Na?O content in a range from 0.01 to 0.2 wt. %, from 0.03 to 0.15 wt. %, from 0.03 to 0.1 wt. %, from 0.04 to 0.15 wt. %, from 0.05 to 0.15 wt. %, or from 0.05 to 0.1 wt. %.

[0207] Aspect 72. The process defined in any one of aspects 1-71, wherein the precipitated ATH product in step (ix) has a soluble Na?O content in a range from 0.001 to 0.01 wt. %, from 0.001 to 0.007 wt. %, from 0.001 to 0.005 wt. %, from 0.002 to 0.01 wt. %, from 0.002 to 0.007 wt. %, or from 0.002 to 0.005 wt. %.

[0208] Aspect 73. The process defined in any one of aspects 1-72, further comprising after step (vii), evaporating water from the suspension to form a concentrated liquor, and recycling the concentrated liquor as a portion of the aqueous caustic solution in step (iv).

[0209] Aspect 74. The process defined in aspect 73, wherein at least a portion of the heat / energy produced in step (ii) is utilized in the step of evaporating water from the suspension after step (vii).

[0210] Aspect 75. The process defined in aspect 73 or 74, wherein at least a portion of the water evaporated from the suspension is utilized for washing in step (vii).

Claims

1. CLAIMSWe claim:

1. A process for producing a precipitated alumina trihydrate (ATH) product from aluminum metal, the process comprising:(i) contacting the aluminum metal with an activating composition comprising gallium and / or indium to form an activated aluminum composition;(ii) reacting the activated aluminum composition with water and an ionic salt, a hydroxide, and / or an acid to form hydrogen (H2) gas and a first reaction mixture comprising solid ATH and a first solid fraction;(iii) isolating the solid ATH and the first solid fraction from the first reaction mixture;(iv) contacting the solid ATH and the first solid fraction with an aqueous caustic solution to form a second reaction mixture containing dissolved sodium aluminate;(v) removing a second solid fraction from the second reaction mixture to form a liquor solution;(vi) seeding the liquor solution with a seed material to precipitate ATH and form a suspension;(vii) isolating precipitated ATH from the suspension and washing the precipitated ATH to form an intermediate ATH product;(viii) optionally, milling the intermediate ATH product; and(ix) drying the intermediate ATH product to form the precipitated ATH product.

2. The process of claim 1, wherein prior to step (i), the aluminum metal is processed in a comminution device to reduce an average particle size or an average thickness of the aluminum metal.

3. The process of claim 1 or 2, wherein the activating composition in step (i) is a liquid eutectic mixture of gallium and indium or a close-to eutectic mixture of gallium and indium.

4. The process of any one of the preceding claims, further comprising before step (ii), milling the activated aluminum composition to form activated aluminum particles.

5. The process of any one of the preceding claims, wherein the hydrogen (H2) gas formed in step (ii) is captured or collected.

6. The process of any one of the preceding claims, wherein: step (ii) produces heat / energy; or step (ii) produces heat / energy, and the heat / energy is converted to steam.

7. The process of any one of the preceding claims, wherein the activated aluminum composition is reacted with water and the hydroxide in step (ii).

8. The process of any one of the preceding claims, wherein the first solid fraction comprises undissolved solids and metals / alloys other than aluminum.

9. The process of any one of the preceding claims, further comprising after step (ii), isolating residual activating composition comprising gallium and / or indium from the first reaction mixture and recycling the residual activating composition for use as a portion of the activating composition in step (i).

10. The process of any one of the preceding claims, wherein at least a portion of heat / energy produced in step (ii) is utilized in step (iv).

11. The process of any one of the preceding claims, wherein: a Na2O concentration of the aqueous caustic solution or the second reaction mixture in step (iv) is in a range from 50 to 200 g / L, from 50 to 150 g / L, from 65 to 120 g / L, from 75 to 100 g / L, from 100 to 180 g / L, from 120 to 170 g / L, or from 130 to 160 g / L, of Na2O (NaOH concertation expressed in terms of Na2O); a NaOH concentration of the aqueous caustic solution or the second reaction mixture in step (iv) is in a range from 1.5 to 7 mol / L, from 1.5 to 5 mol / L, from 2 to 4mol / L, from 2.5 to 3.5 mol / L, from 3 to 6 mol / L, from 3.5 to 5.5 mol / L, or from 4 to 5 mol / L; a molar ratio of Na2O:AhO3 in the second reaction mixture in step (iv) is in a range from 1.2: 1 to 5: 1, from 1.2: 1 to 2.5: 1, from 1.2: 1 to 2: 1, from 1.3: 1 to 1.8: 1, from 1.3:1 to 1.6: 1, from 1.35: 1 to 2: 1, from 1.35: 1 to 1.8: 1, from 1.4: 1 to 1.8: 1, or from 1.4:1 to 1.6: 1; or any combination thereof.

12. The process of any one of the preceding claims, wherein the aqueous caustic solution and the second reaction mixture do not contain solid ATH.

13. The process of any one of the preceding claims, wherein the aqueous caustic solution contains dissolved sodium aluminate.

14. The process of any one of the preceding claims, wherein the second solid fraction contains undissolved solids and other metals / alloys.

15. The process of any one of the preceding claims, wherein: the seed material comprises bayerite alumina trihydrate, gibbsite alumina trihydrate, or a combination thereof; the seed material has a d50 median particle size in a range from 0.1 to 100 pm, from 0.2 to 50 pm, from 0.4 to 20 pm, from 0.4 to 10 pm, from 0.4 to 5 pm, or from 0.8 to 3 pm; the seed material has a unimodal particle size distribution or a bimodal particle size distribution; the seed material has a BET surface area in a range from 0.1 to 50 m2 / g, from 0.5 to 40 m2 / g, from 1 to 30 m2 / g, from 0.1 to 10 m2 / g, from 0.2 to 5 m2 / g, from 10 to 20 m2 / g, or from 25 to 35 m2 / g; or any combination thereof.

16. The process of any one of the preceding claims, wherein an amount of the seed material per liter of the liquor solution is in a range from 0.1 to 20 g / L, from 0.2 to 10 g / L, from 0.4 to 5 g / L, from 0.4 to 2 g / L, from 5 to 20 g / L, or from 10 to 20 g / L.

17. The process of any one of the preceding claims, wherein washing the precipitated ATH in step (vii) is performed in one or more wash cycles with a wash solution comprising water, an alcohol (e.g., ethanol), or a mixture thereof.

18. The process of any one of the preceding claims, wherein the intermediate ATH product in step (vii) has: a d50 particle size in a range from 0.1 to 150 pm, from 0.5 to 120 pm, from 1 to 10 pm, from 1 to 5 pm, from 10 to 100 pm, from 20 to 50 pm, or from 40 to 80 pm; and / or a BET surface area in a range from 0.1 to 20 m2 / g, from 0.1 to 1 m2 / g, from 0.5 to 10 m2 / g, from 1 to 5 m2 / g, from 3 to 15 m2 / g, or from 10 to 20 m2 / g.

19. The process of any one of the preceding claims, wherein the process comprises (viii) milling the intermediate ATH product.

20. The process of any one of the preceding claims, wherein drying the intermediate ATH product in step (ix) comprises spray drying, tray drying, flash drying, freeze drying, oven drying, or microwave drying.

21. The process of any one of the preceding claims, wherein the precipitated ATH product in step (ix) has: a d50 particle size in a range from 1 to 10 pm, from 1.5 to 4.5 pm, from 2 to 5 pm, or from 2 to 3.5 pm; a BET surface area in a range from 1 to 20 m2 / g, from 1 to 10 m2 / g, from 2 to 15 m2 / g, from 2 to 10 m2 / g, from 2 to 5 m2 / g, from 4 to 10 m2 / g, or from 8 to 15 m2 / g; a total Na?O content in a range from 0.01 to 0.2 wt. %, from 0.03 to 0.15 wt. %, from 0.03 to 0.1 wt. %, from 0.04 to 0.15 wt. %, from 0.05 to 0.15 wt. %, or from 0.05 to 0.1 wt. %;a soluble Na20 content in a range from 0.001 to 0.01 wt. %, from 0.001 to 0.007 wt. %, from 0.001 to 0.005 wt. %, from 0.002 to 0.01 wt. %, from 0.002 to 0.007 wt.%, or from 0.002 to 0.005 wt. %; or any combination thereof.

22. The process of any one of the preceding claims, further comprising after step (vii): evaporating water from the suspension to form a concentrated liquor; and recycling the concentrated liquor as a portion of the aqueous caustic solution in step (iv).

23. The process of claim 22, wherein at least a portion of the heat / energy produced in step (ii) is utilized in the step of evaporating water from the suspension after step (vii).

24. The process of claim 22 or 23, wherein at least a portion of the water evaporated from the suspension is utilized for washing in step (vii).

25. The process of any one of the preceding claims, wherein the aluminum metal has a purity of at least 30 wt. %, at least 40 wt. %, at least 50 wt. %, at least 60 wt. %, at least 70 wt. %, at least 80 wt. %, at least 90 wt. %, at least 92 wt. %, at least 95 wt. %, at least 98 wt. %, or at least 99 wt. % aluminum.

Images