METALS EXTRACTION FROM ASH

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63/400,459 filed August 24, 2022, which is expressly incorporated herein by reference.

BACKGROUND

[0002] The supply of critical minerals is a constant concern and a source of potential strategic vulnerabilities for many countries around the globe. These critical minerals are used as main components in the manufacturing of products that the absence of can be detrimental to the country’s economy and national security. Therefore, the solutions to addressing their supply shortage, recycling and recovering from secondary sources are crucial. However, modem recovery methods are often not environmentally friendly, time-consuming, and high energy and costintensive.

[0003] Thus, there is a need for more efficient and environmentally friendly recovery methods. These needs and other needs are at least partially satisfied by the present disclosure.

SUMMARY

[0004] The present invention is directed to a method of recovering critical minerals. In one aspect disclosed herein is a method comprising: a) evaluating a sample of a source comprising a plurality of particles to determine a spatiochemical type of at least a portion of the plurality of particles, wherein the plurality of particles comprise a first quantity of one or more critical minerals, wherein the evaluating comprises at least one of: i) imaging the at least a portion of the plurality of particles; ii) analyzing a chemical composition of the at least a portion of the plurality of particles; iii) measuring an internal connected surface area of the at least a portion of the plurality of particles, or iv) steps of both i) and ii), or i) and iii), or ii) and iii), or i), ii), and iii); b) quantifying a distribution of particles within the at least a portion of the plurality of particles based on the determined spatiochemical type; and c) adjusting a recovery step of the one or more critical minerals based on the determined spatiochemical type.

[0005] In some aspects, the step of imaging comprises scanning electron microscopy (SEM), transmission electron microscopy (TEM), or any combination thereof. While in other aspects, the step of analyzing the chemical composition comprises measurements by Energy Dispersive X-Ray composition analysis (EDX), Inductively Coupled Plasma analysis (ICP), X-Ray Fluorescence analysis (XRF), X- Ray Diffraction analysis (XRD), electron-probe micro analyzer (EPMA), or any combination thereof.

[0006] In yet still further aspects, the recovery step comprises an extraction step. In yet in still further aspects, the extraction comprises recovery from greater than 0% to 100% of the first quantity of the one or more critical minerals. In still further aspects, the one or more critical minerals comprise one or more rare earth metals comprising Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, TM, Yb, Lu, or any combination thereof.

[0007] Also disclosed herein is a system for maximizing a recovery of one or more critical elements comprising: a) a sample comprising a plurality of particles comprising one or more critical elements; b) an imaging device; c) at least one analyzing device; and d) an extraction apparatus; wherein the system is configured: to evaluate a spatiochemical type of at least a portion of the plurality of particles; to quantify a distribution of particles within the at least a portion of the plurality of particles based on the determined spatiochemical type; and to provide a path for maximizing the recovery of the one or more critical minerals based on the determined spatiochemical type.

[0008] Additional aspects of the disclosure will be set forth, in part, in the detailed description, figures, and claims which follow, and in part will be derived from the detailed description, or can be learned by practice of the invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as disclosed. BRIEF DESCRIPTION OF DRAWINGS

[0009] FIGURES 1A-1E depict a PDMS fly ash attachment procedure for single particle leaching microvisualization. FIG. 1A shows a droplet of uncured PDMS placed on pre-heated microscope glass and pre-cured for 5 minutes at 90 °C. FIG. 1B shows sprinkled fly ash on the semi-cured PDMS droplet and further cured at 120 °C for 15 minutes. FIG. 1C- the PDMS substrate is carefully detached from the microscope slide and rinsed with DI water. An aluminosilicate particle enriched with Fe-oxide was SEM imaged (FIG. 1D) before and (FIG. 1E) after acid leaching.

[0010] FIGURE 2 depicts an X-ray diffraction pattern of the ash sample. The major and minor phases include (Q) quartz, (Mu) mullite, (mag) magnetite, (H) hematite, and (A) anhydrite.

[0011] FIGURE 3 depicts REEs total concentrations of a Powder River Basin coal ash sample normalized with respect to the concentrations found in the Upper Continental Crust (UCC).

[0012] FIGURES 4A1-4D depict REEs main occurrences, including (FIG. 4A1) dense aluminosilicate particles, (FIG. 4B1) permeable aluminosilicate particles, and (FIG.4C1) discrete or surface-bound REEs minerals. EDS maps (FIG. 4A2, FIG. 4B2, FIG. 4C2) of the areas highlighted in the SEM images show the chemical composition of associated phases, and (FIG. 4A3, FIG. 4B3, FIG. 4C3) show the EDS point spectra of the REE minerals. (FIG. 4D) The composition of REEs-hosting phases indicates that dense aluminosilicates in blue have lower concentrations of major metals (Al, Ca, Mg, Na, K, Fe) than permeable particles in green. White bar scales correspond to 5 microns.

[0013] FIGURES 5A-5C depict an SEM image of a permeable particle, where unfilled pores are marked in blue and accessible, epoxy-filled pores are depicted in green (FIG. 5A); the pore size distribution for 10 permeable particles shows that most pores found in these particles fall below a pore diameter size of 1 micron (FIG. 5B); the zoomed-in SEM image shows pores as small as ~60nm present in the particle’s matrix (FIG. 5C).

[0014] FIGURE 6 depicts SEM images of REEs remaining after acid leaching.

[0015] FIGURES 7A-7B depict microvisualization of REEs hosting phases before and after leaching. FIG. 7A shows an SEM image of the REEs hosting phases found in the initial ash and the remaining ash after leaching. FIG. 7B shows REEs concentrations, estimated via image analysis, present in each hosting phase prior and after leaching. White bar scales correspond to 2.5 microns.

[0016] FIGURE 8 depicts elemental recovery efficiencies of REEs (in blue) and major metals (in green) following the acid leaching treatment. A slight preferential recovery of lighter REEs is observed. Large variations among major metals recovery are a result of the different bulk mineral phases in the initial ash.

[0017] FIGURES 9A-9B depict major metals (Al, Na, Ca, Mg, Fe) measured in REEs-hosting dense particles, indicating that REEs minerals embedded in metal-rich particles were recovered during AR leaching, leaving only the REEs present in particles with low metal content (FIG. 9A); for permeable particles, there are no significant differences in metal content before and after leaching (FIG. 9B). Due to a limited number of REEs-hosting permeable particles imaged after leaching, FIG. 9B compares overall changes in permeable particles and is not limited to REEs-hosting particles.

[0018] FIGURES 10A1-10C2 depict partially reacted aluminosilicate particles remaining after acid leaching and their corresponding average concentration profiles obtained via SEM-EDS. Radially-leached aluminosilicate particle (FIG. 10A1) shows a metal-rich core based on the (FIG. 10A2) concentration gradient obtained via the EDS linescan. Two unrecovered REEs minerals (white minerals embedded in the particle) (FIG. 10B1 and FIG. 10C1) were found in partially leached aluminosilicate particles. Concentration profiles across the unreacted/leached boundaries (FIG. 10B2 and FIG. 10C2) show varying diffuse layer thicknesses between the two distinct regions. White scale bars represent a lateral distance of 5 pm.

[0019] FIGURE 11 depicts concentration data of shown in FIGs. 10A1-10A2, plus the computed concentration profiles for the reaction-limited case (straight lines) and the diffusion-limited case (dotted lines), computed using a steady state radial diffusion process, under the assumption that the rate of advancement of the unreacted front is slower than the diffusion rate.

[0020] FIGURES 12A1-12C2 depict (FIG. 12A1, FIG. 12B1, and FIG. 12C1)

SEM images of permeable particles found after leaching and (FIG. 12A2, FIG. 12B2, and FIG. 12C2) their corresponding EDS linescans, showing average concentration profiles nearly constant across the particles. REEs recovery from permeable particles, therefore, occurs independently of matrix leaching. White bar scales correspond to 10 microns.

[0021] FIGURE 13 depicts microscale leaching visualization of particles representing the predominant dense and permeable REEs hosting phases. Dense aluminosilicates have their surface minerals leached. Permeable aluminosilicates showed some removal of smaller particles present on their larger pores, suggesting that flow pathways exist within these particles. Discrete/surface-bound REEs minerals or pseudo-phases (i.e. , metal phosphates) could not be easily identified in the PDMS substrate and, therefore, were not imaged.

[0022] FIGURE 14 depicts SEM images of the identified REEs present in dense particles. A total of 75 REEs minerals distributed across 36 dense aluminosilicate particles were analyzed in this study.

[0023] FIGURE 15 depicts REEs minerals present in permeable particles. A total of 12 REEs minerals distributed across 10 particles were identified and analyzed in this study.

[0024] FIGURE 16 depicts REEs minerals present as discrete particles (1-6) and at the surface of aluminosilicates (7-10). A total of 10 REEs minerals in this category were identified.

[0025] FIGURES 17A-17E depict microscopy analysis of REE-bearing particles. FIG. 17A shows thin lamellae were extracted from ash particles by (i) preparing epoxy-mounted ash particles, (ii) argon-ion milling the ash sample, (iii) sectioning off the lamellae from REE-bearing particles, and (iv) attaching the lamellae to a grid to enable the transfer of the sample to the TEM. FIG. 17B shows an HRTEM image of the lamella obtained from a dense matrix particle. Regions delimited by the dashed line correspond to crystalline fragments incorporated in the matrix of the particle. The highlighted yellow boxes indicate where the TEM data is shown in FIG. 17D and FIG. 17E were taken. FIG. 17C shows corresponding EDS elemental maps of silicon, aluminum, and potassium show silicate fragments dispersed in an aluminosilicate continuous phase. FIG. 17D shows an HRTEM image of the amorphous phase, showing no visible lattice fringes. The inset corresponds to the FFT image, showing only a halo and confirming that the aluminosilicate phase is amorphous. FIG. 17E shows an HRTEM image of the silicate fragments, showing lattice fringes and distinct spots in the FFT image, corroborating the crystalline nature of the fragments.

[0026] FIGURES 18A-18D depict a dense matrix particle (FIG. 18A) and a porous matrix particle (FIG. 18B) used in this study. Dashed boxes show the location where TEM lamellas were sectioned off. Insets in FIG. 18C and FIG. 18D show STEM images of the dense and porous matrix lamellas, respectively. The blue boxes highlighted in FIG. 17D indicate where the TEM images depicted in FIGS. 26A-26B were acquired.

[0027] FIGURES 19A-19B depict mechanisms controlling the recovery of REE minerals depend on the crystal structure of the encapsulating ash matrix. FIG. 19A shows dense amorphous matrices enable cation exchange through lattice interstices, while FIG. 19B shows porous crystalline particles are more stable and, consequently, show greater resistance to leaching solutions. The atomic structures presented here are examples of amorphous and crystalline aluminosilicate atomic arrangements. Network formers refer to Si and Al, whereas matrix cations refer to incorporated metals such as alkali metals.

[0028] FIGURES 20A-20B depict STEM-EDS maps of the porous matrix lamella for silicon (blue), aluminum (yellow), and calcium (red) (FIG. 20A) and corresponding EDS spectra and calculated elemental composition (FIG. 20B).

[0029] FIGURES 21A-21E depict particle characterization. FIG. 21 A shows HRTEM imaging of the porous matrix shows lattice fringes of randomly oriented grains, confirming the polycrystalline structure of the matrix. Crystal grains where lattice fringes are harder to distinguish have been magnified, as shown in figures i. to iv. FIG. 21 B shows an HRTEM image of the lamella showing a textured porous matrix indicative of density variations across the material. FIG. 21 C shows an HRTEM image of the porous matrix collected at 120 kX magnification, showing a textured matrix. The computed FFT pattern (inset) shows ring patterns delineated in yellow, indicating that the matrix is polycrystalline. FIGS. 21D-21E show STEM-EDS data of REE-bearing monazite grains present in the lamella.

[0030] FIGURE 22 depicts the HRTEM of the polycrystalline porous lamella. Yellow lines delineate the observed nanograins, and white boxes indicate the location where the high-magnification images of each grain were taken. Images for the grains not depicted here can be found in the main text. The insets, numbered as 1-4, correspond to the calculated FFT patterns used to determine the d-spacing of each grain.

[0031] FIGURE 23 depicts the HRTEM of the polycrystalline porous lamella collected below the location showcased on FIG. 22. Yellow lines delineate the observed nanograins, and white boxes indicate the location where the high- magnification images of each grain were taken. The insets numbered 1-3 correspond to the calculated FFT patterns used to determine the d-spacing of each grain.

[0032] FIGURE 24 depicts the HRTEM of the polycrystalline porous lamella. Yellow lines delineate the observed nanograins, and white boxes indicate the location where the high-magnification images of each grain were taken. The insets numbered 1-6 correspond to the calculated FFT patterns used to determine the d- spacing of each grain.

[0033] FIGURE 25 depicts a frequency plot for d-spacing values calculated using the FFT patterns shown in FIG. 22, FIG. 23, and FIG. 24.

[0034] FIGURES 26A-26B depict STEM images collected from the porous matrix lamella, showing nanocrystals throughout the matrix. Inset images showcase crystal lattice fringes observed in STEM mode. The location where FIGS. 26A-26B were collected, is highlighted in FIG. 18D.

[0035] FIGURES 27A-27B depict a STEM image of REE-bearing minerals, with lattice fringes visible at higher magnifications as shown in the inset image (FIG. 27A) and EDS spectra of the REE-bearing minerals, indicating that they consist of phosphate grains (FIG. 27B). Counts are plotted in log scale.

DETAILED DESCRIPTION

[0036] The present invention can be understood more readily by reference to the following detailed description, examples, drawings, and claims, and their previous and following description. However, before the present articles, systems, and/or methods are disclosed and described, it is to be understood that this invention is not limited to the specific or exemplary aspects of articles, systems, and/or methods disclosed unless otherwise specified, as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. [0037] The following description of the invention is provided as an enabling teaching of the invention in its best, currently known aspect. To this end, those skilled in the relevant art will recognize and appreciate that many changes can be made to the various aspects of the invention described herein while still obtaining the beneficial results of the present invention. It will also be apparent that some of the desired benefits of the present invention can be obtained by selecting some of the features of the present invention without utilizing other features. Accordingly, those of ordinary skill in the pertinent art will recognize that many modifications and adaptations to the present invention are possible and may even be desirable in certain circumstances and are a part of the present invention. Thus, the following description is again provided as illustrative of the principles of the present invention and not in limitation thereof.

DEFINITIONS

[0038] As used herein, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a “rare earth element” includes aspects having two or more such rare-earth elements unless the context clearly indicates otherwise.

[0039] Ranges can be expressed herein as from “about” one particular value and/or to “about” another particular value. When such a range is expressed, another aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect. It should be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint and independently of the other endpoint.

[0040] Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint and independently of the other endpoint. Unless stated otherwise, the term “about” means within 5% (e.g., within 2% or 1%) of the particular value modified by the term “about.”

[0041] Throughout this disclosure, various aspects of the invention can be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, a description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as individual numbers within that range, for example, 1 , 2, 2.7, 3, 4, 5, 5.3, 6 and any whole and partial increments therebetween. This applies regardless of the breadth of the range.

[0042] As used herein, the terms “optional” or “optionally” mean that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0043] References in the specification and concluding claims to parts by weight of a particular element or component in a composition or article, denotes the weight relationship between the element or component and any other elements or components in the composition or article for which a part by weight is expressed. Thus, in a composition or a selected portion of a composition containing 2 parts by weight of component X and 5 parts by weight component Y, X and Y are present at a weight ratio of 2:5, and are present in such ratio regardless of whether additional components are contained in the composition.

[0044] A weight percent of a component, unless specifically stated to the contrary, is based on the total weight of the formulation or composition in which the component is included.

[0045] It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. As used in the specification and in the claims, the term “comprising” can include the aspects “consisting of” and “consisting essentially of.”

[0046] For the terms “for example” and “such as,” and grammatical equivalences thereof, the phrase “and without limitation” is understood to follow unless explicitly stated otherwise. [0047] As used herein, the term “substantially,” when used in reference to a composition, refers to at least about 80%, at least about 85%, at least about 90%, at least about 91 %, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or about 100% by weight, based on the total weight of the composition, of a specified feature or component.

[0048] As used herein, the term “substantially,” in, for example, the context “substantially free,” refers to a composition having less than about 1 % by weight, e.g., less than about 0.5 % by weight, less than about 0.1 % by weight, less than about 0.05 % by weight, or less than about 0.01 % by weight of the stated material, based on the total weight of the composition.

[0049] As used herein, the term “substantially,” in, for example, the context “substantially identical” or “substantially similar,” refers to a method, a composition, an article, or a component that is at least about 80%, at least about 85%, at least about 90%, at least about 91 %, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or about 100% by similar to the method, composition, article, or the component it is compared to.

[0050] As used herein, the term or phrase “effective,” “effective amount,” or “conditions effective to” refers to such amount or condition that is capable of performing the function or property for which an effective amount or condition is expressed. As will be pointed out below, the exact amount or particular condition required will vary from one aspect to another, depending on recognized variables such as the materials employed and the processing conditions observed. Thus, it is not always possible to specify an exact “effective amount” or “condition effective to.” However, it should be understood that an appropriate effective amount will be readily determined by one of ordinary skill in the art using only routine experimentation.

[0051] As used herein, the terms “substantially identical reference composition” or “substantially identical reference method” refer to a reference composition or method comprising substantially identical components or method steps in the absence of an inventive component or a method step. In another exemplary embodiment, the term "substantially," in, for example, the context “substantially identical reference compositions,” refers to a reference composition or a method step that comprises substantially identical components or method steps, and wherein an inventive component or a method step is substituted with a common in the art component or a method step.

[0052] As used herein, the term “critical minerals” is used as defined by the U.S. Geological Survey to be the minerals that are necessary for the manufacture of high technology devices, national defense applications, and green growth-related industries. In still further aspects, these critical minerals include non-fuel minerals or mineral material essential to the economic or national security of the U.S. and which has a supply chain vulnerable to disruption. Exemplary but not limiting critical minerals are aluminum, arsenic, barite, bismuth, cesium, rubidium, chromium, cobalt, fluorspar, germanium, graphite, lithium, magnesium, manganese, platinum group metals, niobium, rhenium, scandium, strontium, tantalum, titanium, tungsten, uranium, vanadium, zirconium, hafnium, tin, indium, tellurium, gallium, antimony, beryllium, rare earth elements (REE) and the like. It is further understood that the U.S. government can update the list of critical minerals, which can be included in the present definition.

[0053] In yet still further aspects, it is understood that a “full strength” of an acid refers to a maximum available concentration of a specific acid used in the disclosure. For example, and without limitations, the "full strength" of HCI is about 12 M, HNOs is about 15 M, HF is about 29 M, etc.

[0054] While aspects of the present invention can be described and claimed in a particular statutory class, such as the system statutory class, this is for convenience only and one of ordinary skill in the art will understand that each aspect of the present invention can be described and claimed in any statutory class. Unless otherwise expressly stated, it is in no way intended that any method or aspect set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not specifically state in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that an order be inferred in any respect. This holds for any possible nonexpress basis for interpretation, including matters of logic with respect to the arrangement of steps or operational flow, plain meaning derived from grammatical organization or punctuation, or the number or type of aspects described in the specification.

[0055] The present invention may be understood more readily by reference to the following detailed description of various aspects of the invention and the examples included therein and to the Figures and their previous and following description.

METHODS

[0056] In certain aspects disclosed herein are methods allowing obtaining one or more critical minerals from secondary sources. It is understood that the secondary source, as described herein, is any source containing at least some amount of the critical minerals that is not an ore source. In certain aspects, the secondary sources can comprise manufacturing waste, materials to be recycled, byproducts of various industries and the like.

[0057] In certain aspects, disclosed herein is a method that allows precharacterization of the secondary source before recovering the critical minerals. In such aspects, the pre-characterization of the secondary source can allow the development of more environmentally friendly, energy-efficient, and cost-conscious methods for the recovery of the desired critical minerals.

[0058] In certain aspects, the methods disclosed herein comprise a step of evaluating a sample of a source comprising a plurality of particles to determine a spatiochemical type of at least a portion of the plurality of particles. In such aspects, the plurality of particles can comprise a first quantity of one or more critical minerals. In still further aspects, the evaluating comprises at least one of: i) imaging the at least a portion of the plurality of particles; ii) analyzing a chemical composition of the at least a portion of the plurality of particles; iii) measuring an internal connected surface area of the at least a portion of the plurality of particles; or iii) steps of both i) and ii), or i) and iii), or ii) and iii), or i), ii), and iii).

[0059] In certain aspects, the source can be any secondary source that comprises a plurality of particles. In some aspects, the source is an ash. Ash is a known pollutant that can be obtained from coal (and/or wood) combustion. Many industries are required to collect the ash to decrease the environmental pollution. Ash is known to contain a large variety of chemical components that can be very valuable if recovered. In certain aspects, the source used in this disclosure is a coal ash. In yet still further aspects, the coal ash can comprise a fly ash, a bottom ash, a boiler slag, a flue gas desulfurization material, or any combination thereof.

[0060] In still further aspects, it is understood that one of ordinary skill in the art can evaluate more than one sample of the source. For example, the methods disclosed herein can comprise steps of evaluating two or more samples of the same source taken from a different location in the source and comparing the evaluation analysis to more to design the recovery processes more efficiently. In still further aspects, the step of evaluating can also comprise collecting samples from different sources and comparing the evaluation analysis for the design of the recovery process.

[0061] In still further aspects, the one or more critical minerals comprise one or more rare earth metals comprising Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, TM, Yb, Lu, or any combination thereof. However, it is understood that the disclosed herein methods can recover other critical minerals.

[0062] In still further aspects, the step of imaging can comprise any known in the art imaging techniques capable of imaging the plurality of particles at the desired resolution. In certain aspects, the step of imaging comprises SEM (scanning electron microscopy), TEM (transmission electron microscopy), or any combination thereof.

[0063] In still further aspects, the step of analyzing the chemical composition can comprise any methods known in the art capable of providing elemental analysis of the desired sample. For example, in some aspects, the step of analyzing comprises measurements by EDX (energy dispersive X-ray analysis), ICP (inductively coupled plasma analysis), XRF (X-Ray fluorescent analysis), XRD (X-Ray diffraction analysis), EPMA (electron probe microanalysis), or any combination thereof.

[0064] In still further aspects, the measuring the internal connected surface area of the at least a portion of the plurality of particles can be done by any known in the art method. For example, and without limitations, it can be done by measuring a BET value of at least a portion of the plurality of particles, gas adsorption, and/or porosimetry using mercury or gas.

[0065] It is understood that the evaluation step can comprise any combination or all of the abovementioned steps. [0066] In still further aspects, the methods disclosed herein can comprise a step of quantifying a distribution of particles within the at least a portion of the plurality of particles based on the determined spatiochemical type. In such aspects, the spatiochemical type comprises a plurality of dense particles, a plurality of at least partially permeable particles, or a combination thereof. It is understood, in some aspects, the at least partially permeable particles can be substantially porous. In yet still other aspects, the plurality of dense particles can be present as a plurality of discrete particles or aggregates. In yet still further aspects, it is understood that the spatiochemical type of the particle can also comprise a plurality of particles that are substantially not dense. In yet still further aspects, some of the particles can be substantially hollow. In yet still, further aspects, the density of the particles can be varied from very dense, dense, substantially dense, porous, highly porous, to substantially hollow.

[0067] In still further aspects, at least a first portion of the first quantity of one or more critical minerals is disposed of within at least a portion of the plurality of dense particles, or within at least a portion of the plurality at least partially permeable particles, or a combination thereof. In yet still further aspects, at least a second portion of the first quantity of one or more critical minerals is surface bounded to one or more of discrete particles of the plurality of particles. In such aspects, the surface- bounded critical mineral can be bound to an outer surface of the discrete particles that are very dense, to dense, to substantially dense, to substantially hollow.

[0068] In still further aspects, the methods disclosed herein comprise a step of adjusting a recovery of the one or more rare earth elements based on the determined spatiochemical type. It is understood that the step of adjusting means that after the spatiochemical type of the particles is determined, the specific recovery steps parameters can be tuned to fit the recovery mechanism based on the spatiochemical type.

[0069] In certain aspects, the recovery step can comprise an extraction step. In certain aspects, the extraction step comprises an acid leaching step, wherein an acid comprises one or more of HF, H2SO4, HNO3, HCI, or any combination thereof. In still further aspects, the acid has a concentration from about 0.1 M to full-strength, including exemplary values of about 0.5 M, about 1 M, about 2 M, about 3 M, about 4 M, about 5 M, about 6 M, about 7 M, about 8 M, about 9 M, about 10 M, about 11 M, about 12 M, about 13 M, about 14 M, about 15 M, about 16 M, about 17 M, about 18 M, about 19 M, about 20 M, about 21 M, about 22 M, about 23 M, about 24 M, about 25 M, about 26 M, about 27 M, about 28 M, about 29 M, and about 30 M. It is understood, however, the full strength of the acid depends on a type of the acid, and therefore, the values provided above are only exemplary.

[0070] In aspects where the recovery step is done by extraction, for example, extraction leaching, the step of adjusting can comprise choosing the specific acid or combination of acids and their concentrations to obtain the faster extraction rate, or adjusting the extraction temperature, or extraction pressure, or extraction time, or any combination thereof.

[0071] In still further aspects, the adjusting step comprises selecting the acid at a predetermined concentration. Yet in still further aspects, the adjusting step comprises selecting the temperature of the leaching step. In still further aspects, the adjusting step comprises adjusting the duration of the leaching step.

[0072] In certain aspects, the extraction can comprise heating a solution of the plurality of particles in any of the disclosed herein acids present at any of the disclosed herein concentrations a temperature from about 20 °C to about 160 °C, including exemplary values of about 25 °C, about 30 °C, about 35 °C, about 40 °C, about 45 °C, about 50 °C, about 55 °C, about 60 °C, about 65 °C, about 70 °C, about 75 °C, about 80 °C, about 85 °C, about 90 °C, about 95 °C, about 100 °C, about 105 °C, about 110 °C, about 115 °C, about 120 °C, about 125 °C, about 130 °C, about 135 °C, about 140 °C, about 145 °C, about 150 °C, and about 155 °C.

[0073] In still further aspects, the acid leaching step has a duration from about 1 min to about 12 months, including exemplary values of 5 min, about 10 min, about 30 min, about 1 h, about 2 h, about 5 h, about 10 h, about 12 h, about 15 h, about 20 h, about 24 h, about 36 h, about 38 h, about 72 h, about 1 week, about 1 month, about 3 months, about 6 months, and about 9 months. It is understood, however, that if the solution still has at least a portion of the first predetermined amount of one or more critical minerals, the leaching step can continue for more than 12 months.

[0074] In still further aspects, wherein the plurality of particles further comprise a second quantity of one or more of Si, Al, Ca, Fe, Mg, Na, K, or any combination thereof. In such aspects, the methods disclosed herein further comprise extracting of the one or more of Si, Al, Ca, Fe, Mg, Na, K, or any combination thereof from the source. In still further aspects, the methods can also comprise steps of separating the one or more of critical minerals from the one or more of Si, Al, Ca, Fe, Mg, Na, K, or any combination thereof.

[0075] In certain aspects, wherein the recovery step comprises recovery from greater than 0% to 100%, including exemplary values of about 1 %, about 5%, about

10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about

45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about

80%, about 85%, about 90%, about 95%, and about 99% of the first quantity of the one or more of critical minerals.

[0076] In yet still further aspects, the recovery step can comprise recovery from greater than 0% to 100%, including exemplary values of about 1 %, about 5%, about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, and about 99% of the second quantity of the one or more of Si, Al, Ca, Fe, Mg, Na, K, or any combination thereof.

SYSTEMS

[0077] Also disclosed herein is a system for maximizing a recovery of one or more critical elements comprising: a) a sample comprising a plurality of particles comprising one or more critical elements; b) an imaging device; c) at least one analyzing device; and d) an extraction apparatus; wherein the system is configured: to evaluate a spatiochemical type of at least a portion of the plurality of particles; to quantify a distribution of particles within the at least a portion of the plurality of particles based on the determined spatiochemical type; and to provide a path for maximizing the recovery of the one or more critical minerals based on the determined spatiochemical type.

[0078] Any suitable samples can be utilized. In some aspects, the sample comprises coal ash. In such aspects, the plurality of particles can have any possible size distribution. As disclosed above, in some aspects, the one or more critical elements can be present in a first quantity. In still further aspects, the one or more critical elements can comprise one or more rare earth metals comprising Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, TM, Yb, Lu, or any combination thereof. [0079] In still further aspects, the plurality of particles further comprises one or more of Si, Al, Ca, Fe, Mg, Na, K, or any combination thereof present in a second quantity.

[0080] In yet still further aspects, the system is configured to extract the one or more critical elements according to the methods disclosed above. In yet still further aspects, the system is configured to separate the one or more critical elements from Si, Al, Ca, Fe, Mg, Na, K, or any combination thereof.

[0081] In still further aspects, the system comprises an imaging device. In such aspects, the imaging device can comprise one or more of SEM, TEM, or any combination thereof. It is understood that these imaging devices can be used to image the sample according to the methods and examples disclosed herein.

[0082] In yet still further aspects, the system comprises at least one analyzing device. In such aspects, the at least one analyzing device can comprise EDX, ICP, XRF, XRD, EPMA, or any combination thereof. In still further aspects, these analyzing devices can be used to analyze the sample according to the methods and examples disclosed herein.

[0083] In still further aspects, the system comprises an extraction apparatus. In such aspects, the extraction apparatus is configured to receive and hold any material that can assist in extracting one or more critical elements. In such exemplary aspects, the extraction apparatus is configured to hold an extraction acid solution comprising one or more of HF, H2SO4, HNO3, HCI, or any combination thereof. It is understood that the extraction acid can be present in any concentration effective to provide the desired extraction level of the one or more critical elements. In still further aspects, maximizing the extraction output can comprise tuning the concentration of the acid based on the imagining and analyzing of the sample.

[0084] In still further aspects, the extraction apparatus is configured to withstand temperatures of about 20 °C to about 160 °C, including exemplary values of about 30 °C, about 40 °C, about 50 °C, about 60 °C, about 70 °C, about 80 °C, about 90 °C, about 100 °C, about 120 °C, about 140 °C, and about 150 °C for up to about 12 months, for example, for 1 min to about 12 months, including exemplary values of of 5 min, about 10 min, about 30 min, about 1 h, about 2 h, about 5 h, about 10 h, about 12 h, about 15 h, about 20 h, about 24 h, about 36 h, about 38 h, about 72 h, about 1 week, about 1 month, about 3 months, about 6 months, and about 9 months. In still further aspects, the extraction apparatus is configured to continue extraction according to the methods disclosed herein until substantially all first quantity of the one or more critical elements is recovered. It is understood, however, that if the solution still has at least a portion of the first predetermined amount of one or more critical minerals, the extraction apparatus can continue extraction for more than 12 months.

[0085] In still further aspects, the system can comprise a controller. In such aspects, the controller can control any system parts individually or simultaneously. In yet still further aspects, the system can comprise various computing devices.

[0086] As disclosed herein, computing devices can contain communication connection(s) that allow the device to communicate with other devices if desired. Computing devices can also have input device(s) such as a keyboard, mouse, pen, voice input device, touch input device, etc. Output device(s) such as a display, speakers, printer, etc., can also be included. All these devices are well-known in the art and need not be discussed at length here.

[0087] Computer-executable instructions, such as program modules being executed by a computer, can be used. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform particular tasks or implement particular abstract data types. Distributed computing environments can be used where tasks are performed by remote processing devices that are linked through a communications network or other data transmission medium. In a distributed computing environment, program modules and other data can be located in both local and remote computer storage media, including memory storage devices.

[0088] A computing device typically includes at least one processing unit and memory in its most base configuration. Depending on the exact configuration and type of computing device, memory can be volatile (such as random-access memory (RAM)), non-volatile (such as read-only memory (ROM), flash memory, etc.), or some combination of the two. [0089] Computing devices can have additional features/functionality. For example, a computing device can include additional storage (removable and/or nonremovable), including, but not limited to, magnetic or optical disks or tape.

[0090] Computing device typically includes a variety of computer-readable media. Computer-readable media can be any available media that can be accessed by the device and includes both volatile and non-volatile media, removable and nonremovable media.

[0091] Computer storage media include volatile and non-volatile and removable and non-removable media implemented in any method or technology for information storage, such as computer-readable instructions, data structures, program modules, or other data. Memory, removable storage, and non-removable storage are all examples of computer storage media. Computer storage media include but are not limited to, RAM, ROM, electrically erasable program read-only memory (EEPROM), flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by a computing device. Any such computer storage media can be part of a computing device.

[0092] Computing devices, as disclosed herein, can contain communication connection(s) that allow the device to communicate with other devices. The connection can be wireless or wired. Computing devices can also have input device(s) such as a keyboard, mouse, pen, voice input device, touch input device, etc. Output device(s) such as a display, speakers, printer, etc., can also be included. All these devices are well-known in the art and need not be discussed at length here.

[0093] It should be understood that the various techniques described herein can be implemented in connection with hardware components or software components or, where appropriate, with a combination of both. Illustrative types of hardware components that can be used include Field-programmable Gate Arrays (FPGAs), Application-specific Integrated Circuits (ASICs), Application-specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), etc. The methods and apparatus of the presently disclosed subject matter, or certain aspects or portions thereof, can take the form of program code (i.e., instructions) embodied in tangible media, such as CD-ROMs, hard drives, or any other machine-readable storage medium where, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the presently disclosed subject matter.

EXAMPLES

[0094] The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the compounds, compositions, articles, devices and/or methods claimed herein are made and evaluated and are intended to be purely exemplary and are not intended to limit the disclosure. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.), but some errors and deviations should be accounted for.

[0095] Unless indicated otherwise, parts are parts by weight, temperature is degrees C or is at ambient temperature, and pressure is at or near atmospheric or full vacuum.

[0096] Current approaches to recover REEs from fly ash are challenged by a limited understanding of the fundamental particulate material properties and reactive transport processes. Distinct transport and reactive phenomena take place at the sub-particle-level during REEs recovery treatments. The inventors found that crystallinity strongly impacts the reactivity and ion diffusivity of material phases, and the results are shown here.

EXAMPLE 1

Full Digestion for Initial Elemental Characterization

[0097] Approximately 35 mg of fly ash were dissolved overnight using a 1 mL mixture of concentrated HF and HNOs at a 1 :1 ratio. A mixture of HF and HNO3 at a 4:1 volumetric ratio, respectively, was added to each beaker, and the digestion was carried out for three days. The samples were re-digested with 2 mL of HNO3 overnight, followed by a 1 mL HCI digestion for three days. Beakers were ultrasonicated, and the hydrochloric acid digestion was repeated until the full dissolution was achieved. All digestions were carried at 160° C, and samples were dried in between digestion cycles. All resulting effluents were dried down and redissolved by adding 2 milliliters of 3 M HNOs. Appropriate dilutions were carried out, and trace elemental composition was determined via inductively coupled plasma mass spectrometry (Agilent 7500 ICP-MS). Initial digestion was run in triplicate.

Leaching Procedure

[0098] For the acid leaching experiments, samples were digested with 2 mL of full-strength aqua-regia for three days at 120 °C. Following the acid digestion steps, samples were centrifuged, and leachates were transferred to clean beakers. All resulting effluents were dried down and re-dissolved by adding 2 milliliters of 3 M HNO3. Appropriate dilutions, as described for the fully digested samples, were carried out, and trace elemental composition was determined via inductively coupled plasma mass spectrometry (Agilent 7500 ICP-MS). Leaching experiments were run in triplicate.

Microscale Analysis via SEM-EDS

[0099] Spatial elemental characterization was conducted using a Scios 2 HiVac scanning electron microscope (SEM) equipped with an energy-dispersive X-ray (EDX) detector and a backscattered electron detector (BSE). Visualization and EDX elemental mapping of the internal structure of fly ash were achieved at a voltage of 10 kV. At this operating voltage, the EDX depth of investigation was estimated to be ~0.6 microns based on Monte Carlo Simulations conducted using the Casino software. EDS linescan concentration profiles were obtained as duplicates, ~100 nm apart, and using a working voltage of 5 kV to reduce the volume of investigation.

Microscale Leaching Experiments

[00100] The PDMS-bound fly ash particulates were imaged before and after acid leaching using the Scios 2 HiVac SEM at a working voltage of 2-5 kV. EDS chemical data could not be properly collected due to charge accumulation resulting from the poor surface conductivity of the polymer. Notably, the particle attachment procedure depends on sample composition and heterogeneity. The methods described above were optimized to retain the greatest number of ash particles samples. When tested using 5-micron magnetite particles, longer curing periods (an extra 5 min) were required to increase the PDMS viscosity and prevent complete particle embedment. ICP-MS Measurements

[00101] Major, minor, and trace elemental analyses were conducted using inductively coupled plasma mass spectrometry (ICP-MS, Agilent 7500) in solution mode. Digestion effluents were diluted to less than 200 ppm of total dissolved solids for the trace elements analysis, and further diluted by a factor of 75 for the major and minor elemental analysis. Diluted aliquots were analyzed using three reaction cell modes: no gas mode, collision mode with helium, and reaction mode with hydrogen. Rare earth elements were analyzed in collision mode with helium. Major elements were analyzed using all three modes; the final reported concentrations were selected based on the mode that yielded the most statistically robust measurements based on the quality control standards analyses.

EXAMPLE 2

[00102] Rare earth elements (REEs), comprised of the lanthanides group plus yttrium and scandium, are critical material components for the manufacturing of key technologies used in energy, transportation, medicine, and electronics. Goods and materials requiring REEs, for instance, accounted for ~ 10 % of the global economy in 2018. As a result of their ubiquitous use and lack of suitable substitute materials, REEs demand is expected to increase in the upcoming years, with neodymium and dysprosium demands rising as high as 1100% and 2400%, respectively, by 2050. Identifying nontraditional sources of REEs is, therefore, fundamental to ensure that ever-increasing societal needs are met.

[00103] Coal fly ash, the microscopic (1 to 100 pm) aerosolized waste material from coal combustion, offers a promising alternative for REEs recovery, supporting a circular economy model in resources exploration. Excitingly, fly ash contains REEs concentrations of up to 1500 ppm and is an abundant and accessible hazardous material. Between the years 2000 to 2019, the U.S. produced more than 1 billion short tons of fly ash, and yet only ~ 42 % of it was repurposed. The unused fly ash is traditionally disposed of in landfills and poses environmental concerns over the leaching of heavy metals into local hydrology. Of equally harsh environmental impact are conventional REEs mining operations. Specifically, land clearing and excavation, high energy usage, greenhouse gas emissions, and acid mine drainage severely impact neighboring ecosystems. Heavy REEs mining, for example, consumes up to 20 times more energy than steel making. Repurposing unused fly ash as a REEs resource, therefore, presents an opportunity to help meet REEs demands while simultaneously reducing the environmental footprint associated with current ash disposal and ore mining practices.

[00104] Extracting REEs from fly ash relies on reagent-based methods such as acid leaching. Key questions remain, however, on the underlying processes that control REEs recovery. Specifically, previous bulk recoveries range from ~ 20 to 100 % and render the prediction and control of REEs extraction from coal wastes challenging. The recovery of REEs via leaching is directly impacted by their spatial distributions across the fly ash matrix. Previous studies have focused on the REEs modes of occurrence or their bulk extractability and macroscale recovery control factors. The understanding of the coupling between microscale properties of fly ash and the mechanisms dictating REEs accessibility, however, is still lacking.

Specifically, at the microscale, reactive transport is controlled by the local chemical and morphological variations of the REEs-hosting phases, which have not been accounted for in bulk-scale experiments. To develop economic- and ecologically- feasible extraction methods, therefore, a fundamental understanding of the processes dictating REEs recovery is critical.

[00105] In this disclosure, a spatiochemically-resolved characterization of fly ash is provided. Also, the correlation between the physicochemical properties of the ash to unique extraction mechanisms is investigated. Specifically, the processes dictating REEs recovery from fly ash by examining the microscopic properties of REEs- hosting phases pre- and post-recovery were studied. It was discovered that REEs recovery from dense aluminosilicates, the most common REEs-hosting particles, is controlled by the reaction-limited progressive leaching of metals in the encapsulating phase. Without wishing to be bound by any theory, it was suggested that the recovery of REEs minerals hosted in permeable aluminosilicates, on the other hand, was enabled by intraparticle pore fluid flow.

[00106] Moreover, morphological changes were negligible for both dense and permeable aluminosilicate particles, as evidenced by microvisualization leaching experiments. Discrete and surface-bound REEs minerals were also found in this study and, due to their direct accessibility, their recovery is controlled only by the dissolution kinetics of the REEs mineral. The current disclosure shows how elemental composition and the morphology of the hosting particles, enable or hinder the recovery of REEs from fly ash and inform the design of more efficient REE extraction processes.

Materials and Methods

Initial Phase and Elemental Characterization

[00107] A fly ash sample from Powder River Basin feed coal was used in this study. The phases present in the fly ash were characterized using X-ray diffraction (XRD, Rigaku R-Axis Spider). Major elemental composition was determined via X- ray fluorescence (XRF, NSL Analytical). REEs concentrations, as well as other trace element content, were quantified via acid digestion followed by inductively-coupled plasma mass spectrometry (Agilent 7500 ICP-MS). Specifically, acid digestions were carried out in triplicate using hydrofluoric acid (optima grade HF, Fisher Scientific), hydrochloric acid (trace metal grade HCI, Fisher Scientific), and double-distilled nitric acid (15 M HNOs, Fisher Scientific), until the ash was fully dissolved.

[00108] Microscale spatial characterization of the ash was performed using a scanning electron microscope (SEM, Scios 2 HiVac) equipped with energy- dispersive X-ray spectroscopy (EDS) detector and a backscattered electron (BSE) detector. The initial ash sample was mounted in epoxy (Ted Pella), hand-polished, Argon ion-milled, and carbon-coated to enable direct visual access to the interior of the ash particles. To understand the microscale properties controlling REEs accessibility, elemental distribution (via EDS) and morphologic data of 97 REEs minerals and their associated hosting phases (i.e. , the bulk ash particles) were collected from the initial ash sample. Quantitative data was collected by performing SEM and EDS image analyses.

Acid Leaching Experiments

[00109] Leaching experiments were conducted using aqua regia (AR), a 3:1 ratio mixture of 12 M HCI to 15 M HNO3, and the resulting effluents and solids were analyzed to understand the processes dictating REEs recovery. For each run, approximately 35 mg of ash were leached in 2 mL of AR for three days at 120 °C. The effluent was diluted and analyzed using ICP-MS. The solid residue was epoxymounted following the method described for the initial characterization.

Characterization of elemental distribution and morphologic changes to the ash residue was performed using SEM to identify and compare the microscale properties of the remaining REEs hosting phases to the initial ones. The Mann-Whitney II test was used to determine if statistical differences exist between the composition of REEs hosting particles pre- and post-leaching.

Single Particle Leaching

[00110] Direct micro and nanoscopic visualization of the leaching process was facilitated by a particulate attachment procedure (FIGS 1A-1E). Specifically, Sylgard 184 silicon elastomer (PDMS, Dow) was mixed using a 10:1 ratio of base to curing agent, degassed, and a drop (~ 100 pL) of the mixture was placed on a glass microscope slide that was pre-heated to 90 °C. The PDMS was cured partially for 5 min at 90 °C before fly ash was sprinkled on top. The semi-cured PDMS, with ash embedded, was heated at 120 °C for an additional 15 min to finish curing. The ash- embedded PDMS was rinsed using deionized (DI) water to remove those particles that had not been secured in the PDMS, and the substrate was air-dried overnight. The leaching of PDMS-bound fly ash particulates was imaged for morphological changes using SEM, before and after leaching the substrate with AR for 2 hours at 70 °C.

EXAMPLE 3

Results and Discussion

Initial Ash Characterization

[00111] The major metals present in the fly ash, measured using XRF, include aluminum (17.5 %), calcium (6.0%), iron (4.3 %), magnesium (2.4 %), sodium (1.6 %), and potassium (1.2 %). As determined by XRD measurements, the major and minor phases present include an amorphous phase, quartz, mullite, hematite, and anhydrite (FIG. 2). SEM imaging revealed that ash particulates, predominantly composed of aluminosilicate oxides, ranged in size between sub-micron levels to ~60 microns. Total REEs concentrations in the acid-digested sample were 384 ± 32 ppm using ICP-MS (Table 1), and when normalized relative to the upper continental crust (FIG. 3), no preferential enrichment towards light or heavy lanthanides was observed. The REEs minerals identified in this study via SEM-EDS imaging consisted of light REEs (La, Ce, Nd) phosphates, as well as Y minerals. [00112] Interestingly, REEs minerals were found in three modes of occurrence (FIGs. 4A1-4D): (i) dense aluminosilicate particles, as reported previously (~ 78 %, FIGs. 4A1-4A3), (ii) permeable aluminosilicate particles (~ 12 %, FIGs. 4B1-4B3), and (iii) discrete or surface-bound minerals (~ 10 %, FIGs. 4C1-4C3). Specifically, the inventors have identified morphologic differences in the hosting phases (dense versus permeable particles) that influence REEs accessibility and, therefore, the reactive transport mechanisms that control their recovery from fly ash.

Table 1. Minor and trace elemental composition, including rare earth elements, was measured using ICP-MS.

Li V Cr Mn Co Ni Cu Zn As Rb Sr Zr Ba Pb Th U

Cont 93. 108 73. 26 10. 26. 89. 62. 20. 51. 166 19 376 47. 21. 8.

8 0 6 2 6 2 4 7 8 4 1 8 4 7 8

(ppm

)

Sc Y La Ce Pr Nd Sm En Gd Tb Dy Ho Er Tm Yb Ln

Cont 17. 58. 71. 13 14. 53. 10. 2.5 10. 1.6 9.1 1.9 5.4 0.8 5.1 0.

3 8 0 0 7 4 2 4 8

(ppm

)

[00113] First, dense aluminosilicates constitute the main REEs-hosting particle type. It was found that for dense aluminosilicate particles, concentrations of aluminum range from < 1 to ~ 12 wt. %. Minor concentrations of metals, such as Ca, Mg, Na, K, and Fe, were also found dispersed throughout the glassy phase (8 wt. % on average). It is worth noting that some REEs minerals were found in particularly SiOx-enriched phases, although a clear compositional cutoff among dense particles could not be established (FIG. 4D). Structurally, dense particles are compact and, although pores occur as a result of entrapped volatile molecules, they lack the interconnectivity required for intraparticle fluid transport.

[00114] Second, permeable aluminosilicate particles host REEs minerals, to a lesser extent (~ 12 %), in their matrices. Their chemical composition consists of high aluminum content (21 ± 2 wt. %), with an Al: Si ratio, on a wt. basis of nearly 1 . Minor metals (Ca, Na, Mg) occur only in small concentrations (<4 wt. % in total). Notably, permeable particles are highly porous (porosity up to ~ 32%), presenting pore interconnectivity that enables intraparticle fluid flow (e.g., epoxy partially filling accessible pores in FIGs. 5A-5C, green). The chemical and physical features of permeable aluminosilicates suggest that these particles, which potentially originated from clay minerals, were poorly exposed to the combustion furnace. Moreover, permeable particles appear to be the original material of amorphous spheres attached to their surfaces (FIG. 5A), further indicating an incomplete phase change of the permeable particulate.

[00115] Lastly, discrete as well as surface-bound particles are recovered easily because of direct access to their surfaces by reagents. Without wishing to be bound by any theory, it was suggested that the dissolution of these particles can be governed by thermodynamics and kinetics. Their recovery extent, and rate, are greater than those of the former two modes of REEs occurrences.

REEs Distribution and Phase Association after Leaching

[00116] Microscale SEM-EDS analysis of the leached ash (FIG. 6) shows that, whereas discrete/surface-bound REEs minerals and the REEs minerals hosted in permeable aluminosilicates were recovered, a small portion of REEs minerals hosted in dense aluminosilicates remained trapped in the solid residue (FIGs. 7A-7B). No discrete or surface-bound REEs minerals after leaching (i.e. , ~ 100 % recovery) were found. Permeable particles were only associated with ~ 4 % of the remaining REEs minerals found in the ash, indicating that ~92% of the REEs hosted in permeable particles were recovered. Lastly, although REEs hosted in dense aluminosilicates represent the majority of the unrecovered REEs minerals, ~ 70 % of REEs encapsulated in the dense particles were recovered. The image analyses show a total REEs recovery of ~ 69 %, consistent with the REEs recovery of ~ 63 % measured in the leachates via ICP-MS (FIG. 8).

REEs Recovery from Dense Aluminosilicates

[00117] A strong relationship between REEs recoverability and the concentration of major metals (Al, Ca, Mg, Na, Fe) in the hosting particulates was observed. The analysis of the REEs-hosting particles before and following leaching using SEM-EDS enables the tracking of bulk chemical and morphological changes that occur on dense particles (FIGs. 14-16). Notably, most REEs minerals in dense aluminosilicates with high metal content were recovered via acid leaching, whereas REEs in particles with lower concentrations of metals were not recovered (FIG. 9A, Table 2)

[00118] A heterogeneous surface reaction coupled with cation interdiffusion governs REEs recovery in high-metal content particles. Notably, concentration profiles of partially reacted metal-rich particles obtained via EDS linescans, indicate that major metals (Al, Ca, Mg, Na, Fe) are recovered, layer by layer, from the matrix of the particle during leaching (FIGs. 10A1-10C2). Specifically, outer metal-poor leached regions are found surrounding inner metal-rich cores that are unreacted (FIGs. 10A1-10A2). The metals released at the leached-unreacted interface migrate through the metal-poor shell through the interdiffusion of matrix metals and H ⁺ ions in the solution. Remaining REEs minerals after the acid leach were found in the unreacted regions of the particles (FIGS. 10B1-10C2). Without wishing to be bound by any theory, it was hypothesized that the leaching of surrounding mobile cations present in the ash matrix is a required step to enable the delivery of reagents to REEs minerals and their subsequent recovery. It is worth noting that such outer metal-poor shells in the partially-reacted particles were not formed during coal combustion; no such particles were present in the initial ash and the higher melting points of silicate minerals favor limited to no phase changes; therefore, silicate condensation onto other phases was assumed to be unlikely.

Table 2 The Mann-Whitney U test was used to determine if differences exist in the major metal content of REEs-hosting particles, before and after leaching. The data shows that statistical differences exist between the composition of dense particles before and after leaching, whereas permeable particles pre- and post-leaching show statistically similar metal content. dense particles permeable particles

(initial vs. leached) (initial vs. leached)

U 352 30 p-value <0.001 0.574

[00119] Surprisingly, the outer leached layers and sharp concentration gradients (thickness < 1 pm), herein called diffuse layers, across partially-reacted particles indicate that the leaching reaction kinetics, rather than ionic diffusion through the matrix, controls the metal leaching process in metal-rich particles. The existence of an unreacted region with uniform composition following the three-day leaching period indicates that the release of mobile cations at the unreacted core-leached layer interface is extremely slow. Moreover, the sharp concentration profiles measured follow closely those of reaction-limited processes, whereas the spreading wave profile characteristic of diffusion-limited reactive transport was not observed (FIG. 11)

[00120] Approximately 30 % of REEs found in dense aluminosilicates were unrecovered. REEs-hosting dense particles that withstood the leaching were predominantly metal-poor, suggesting that a low metal content in the surrounding matrix may slow or fully inhibit the recovery of REEs. Moreover, crystal lattice order may be preserved in SiOx-rich phases, further restricting the ability of the matrix to allow metals release during leaching.

REEs Recovery from Permeable Aluminosilicates

[00121] REEs minerals hosted in permeable particles that are poorly burnt and highly porous were recovered almost in their entirety (~92 %). Surprisingly, however, it was found that the REEs recovery is controlled mainly by fluid flow through the pores, with little to no contributions from matrix leaching. Chemical data collected after leaching reveals negligible changes in the main composition of the matrix. That is, unlike the dense particles, there are no statistical differences between the composition of the particles before and after leaching (FIG. 9B, Table 2). Moreover, the concentration profiles of major metals across the leached permeable particles remain unchanged as a result of leaching (FIGs. 12A1-12C2). Without wishing to be bound by any theory, it was assumed that due to the preservation of crystallinity due to incomplete phase conversion, these particles withstand the leaching treatment despite having higher metal concentrations than dense particles. These findings suggest that for permeable particles, metal removal from the matrix of the particle is slower than the fluid’s ability to travel through the entire particle. REEs recovery is, therefore, controlled by fluid flow through the particle rather than by the sequential leaching of cations present in the particle’s matrix.

REEs Recovery from Discrete and Surface-Bound Minerals

[00122] Discrete and surface-bound REEs minerals were fully recovered during acid leaching. Their direct surface exposure enables REEs minerals dissolution with no requirements of glass leaching (as in dense particles) or fluid flow through intraparticle pores (as in permeable particles). For this type of REEs occurrence, recovery is limited by the kinetics of REEs mineral dissolution at the mineral surface and the saturation conditions of the solution.

Examining Morphological Changes as a Result of Leaching

[00123] Microscale physical properties of the REEs-hosting particles influence the recovery of REEs from them. To investigate potential morphological changes that occur during leaching ex-situ ash leaching, micro/nano-visualization experiments were performed where PDMS-embedded ash was characterized. No major morphological changes were observed in the dense aluminosilicate particles following acid leaching (FIG. 13). Nanosized (< 1 pm) minerals attached to the particle surfaces were consistently dissolved, yet no visible physical changes to the particle bulk structure were observed. These findings corroborate that the recovery of REEs is controlled by ion exchange across the glass matrix, with little to no changes to the morphology of dense particles. Similarly, permeable aluminosilicates do not undergo morphologic changes following acid leaching. Smaller particles contained in the particle pores, however, appear to be removed, further suggesting that these particles enable flow through their pores.

Implications

[00124] Identifying nontraditional sources of REEs is essential for secure and reliable access to critical metals such as REEs. Recovering REEs from coal fly ash bridges the gap between increasing demands and limited conventional resources. To improve the recovery efficiency and to reduce the environmental impact of REEs extraction, however, the processes that dictate REEs recovery at the scales where they occur need to be understood. The methods disclosed herein can also allow the cleanup of wastes that are hazardous to the environment, ecology, and human health.

[00125] The current study has shown that REEs recovery is mainly controlled by intraparticle processes. Specifically, a microscale analysis of REEs minerals associations in the initial ash, and the phases associations and properties of the accessible and inaccessible REEs minerals was provided. Three types of REEs minerals occurrences were found: embedded in dense particles, embedded in permeable particles, and discrete or surface-bound REEs minerals. Most REEs minerals were found encapsulated in dense aluminosilicates, and their recovery relies on the sequential leaching of metals in the surrounding phases that enables reagents to reach the encapsulated REEs minerals via matrix diffusion. Other REEs- minerals hosting phases were identified, namely permeable aluminosilicates and discrete or surface-bound REEs minerals. The recovery mechanisms for these two phases are less influenced by the ash matrix chemistry since permeable aluminosilicates allow fluid flow and discrete/surface-bound REEs minerals are directly exposed to the leaching solution. Without wishing to be bound by any theory, it was indicated that kinetic studies conducted at a bulk scale might fail to fully uncouple the different release rates of each mode of occurrence. Again, without wishing to be bound by any theory, it was suggested that the rate of release of discrete and surface-bound particles be the fastest, followed by permeable particles, and lastly by dense particles. A spatiochemical understanding of microscale phenomena occurring during leaching is, therefore, fundamental to better predicting REEs recovery rates at larger scales.

EXAMPLE 4

Materials and Methods

[00126] A fly ash sample from Powder River Basin was used in this study (Table 3). The bulk and microscale properties of this ash sample are reported in prior examples. In summary, the bulk mineralogy of the fly ash consists of amorphous aluminosilicate, quartz, hematite, mullite, and anhydrite. The total REEs content in this sample is 384 ± 32 ppm. Approximately 90% of REE-bearing minerals identified via micro-visual characterization were encapsulated in the dense and porous matrix aluminosilicate particles; the remainder were either discrete or bound to the surface of ash particles and were accessible to leaching reagents directly.

[00127] The crystallinity of REE-bearing particles was investigated using electron microscopy techniques (FIG. 17A). Dense and porous ash particles containing REE minerals were identified in epoxy-mounted, Argon-ion milled ash using scanning electron microscopy (SEM, Scios 2 HiVac Dual-Beam, FIG. 17A, FIGS. 18A-18D). Thin lamellae were extracted from the matrix of the particles using a focused ion beam (FIB), attached to a lift-out grid, and further milled to a thickness of ~ 100 nm. The lamellae were imaged using scanning transmission electron microscopy (STEM, JEOL neoARM) in TEM and STEM modes at 200 keV. Annular darkfield (ADF) STEM imaging coupled with EDS was performed to evaluate the elemental composition of the matrix of the REE-hosting ash particles. High-resolution TEM (HRTEM) and Fast Fourier Transform (FFT) were used to investigate the crystallinity of the REE-bearing ash matrix lamellae. Matrix lattice characteristics (i.e., d-spacing) were calculated from the FFT patterns using Imaged image analysis software.

Table 3. Summarized composition of the ash used. The elemental composition was obtained via ICP-MS analysis of digested ash samples, and the REE- hosting phases were obtained via SEM-EDS microscale visual analysis.

Elemental Composition via ICP-MS

Elements Concentration (ppm)

Na 12,324 ± 205

Mg 15,190 ± 240

Al 89,438 ± 188 j ****

K 9,958 ± 52

Ca 43,478 ± 814

Ti 5,285 ± 77

Mn 267 ± 8

Fe 29,464 ± 1332

Sr 1 ,664 ± 70

Zr 191 ± 7

Ba 3,769 ± 72

Total REEs 384 ± 32

REEs Microscale Spatial Distribution

REEs-hosting Phases Percentage (%)

Dense Matrix Particles 78

Permeable Matrix Particles 12

Discrete/Surface-bound REEs 10

Results and Discussion

Dense Matrix Particles

[00128] STEM-EDS data reveal that the matrix of the dense particle consists primarily of an aluminosilicate phase, with silicate fragments incorporated throughout (FIGS. 17B-17C). Overlapping elemental maps of silicon, aluminum, and oxygen across the continuous phase suggest that the matrix is an aluminosilicate. The fragments, in contrast, are characterized by Si and 0 without aluminum signals, indicating that their composition consists of silicon oxide (i.e. , silicate, FIG. 17C). [00129] Notably, HRTEM crystallinity data of the dense matrix lamella showed two distinct phases: a continuous amorphous phase that coincides with the aluminosilicate material and crystalline regions coinciding with the silicate fragments (FIGS. 17A-17E). The crystallinity of the continuous aluminosilicate phase and of the silicate fragments were determined using three data sets: (i) the location and distribution of Fresnel fringes in HRTEM images; (ii) the presence, or lack of, lattice fringes in HRTEM; and (iii) the corresponding FFT patterns of the HRTEM data. First, Fresnel fringes, indicative of crystal boundaries and dislocations, were observed across the silicate fragments but not in the continuous aluminosilicate phase (FIG. 17B). Second, the absence of crystalline lattice fringes confirms that the aluminosilicate phase is amorphous (FIG. 17D). Notably, the corresponding FFT shows only a halo and lacks distinct spot patterns, further corroborating the amorphous nature of the aluminosilicate phase. In contrast, HRTEM imaging of the silicate fragments exhibited lattice fringes that indicate periodic crystal lattices in the silicate phase (FIG. 17E). Spot patterns are noticeable in the FFT data of the silicate fragments, with a lattice d-spacing of 2.2 A (FIG. 17E).

[00130] Amorphous phases found in fly ash present structural interstices (i.e. , free volume within the lattice network) that enable the transport of chemical species and facilitate access to REEs encapsulated by dense matrices (FIG. 19A). Specifically, variations in bond lengths and angles rotated lattice units, as well as the incorporation of alkali and alkali-earth metals, disrupt the lattice network and create ring structures that generate interstitial volume. Metal cations (i.e., Mg, Ca, Na, K) in the amorphous ash matrix are thus able to use the interstices to diffuse outwardly in exchange for protons that diffuse into the matrix of the particle. Proton access to REEs encapsulated within dense matrix particles, therefore, does not require interconnected porosity but rather is enabled by the lattice interstices available in their amorphous phase. Leaching methods, however, generally lack selectivity and result in the indiscriminate release of cations, including non-REE species, from the amorphous matrix. A tradeoff, therefore, exists in REEs recovery from dense amorphous particles, where REEs extraction is accompanied by contaminated solutions that require intensive separation downstream.

Porous Matrix Particles [00131] STEM-EDS elemental data of the porous matrix showed a homogeneous aluminosilicate composition across the lamella (FIGS. 20A-20B). Elevated concentrations of silicon and aluminum were detected throughout the matrix with a Si: Al ratio of 1 :1 , whereas alkali/alkali-earth cations were only found at minor levels (FIGS. 20A-20B). The porous internal morphology and elemental composition of these particles (i.e., 1 :1 ratio of Si:AI) resemble those of calcined clay particles.

[00132] HRTEM characterization shows that the porous lamella was comprised of a polycrystalline matrix that consists of randomly oriented nanocrystals (~ 10 to 100 nm, FIGS. 21A-21E). HRTEM data collected from the matrix showed distinctly oriented crystal grains across the matrix of the lamella with d-spacing values ranging from 1.3 to 5.5 A (FIG. 21 A, FIG. 22, FIG. 23, FIG. 24, FIG. 25). Importantly, textural heterogeneity across the lamella, indicative of spatial density variations, shows that the polycrystalline behavior extends across the entire matrix (FIGS. 21B-21C, FIGS. 26A-26B). Ring patterns in the FFT data, with predominant d-spacings of 3.5 and 5.5 A, further corroborate the existence of polycrystallinity in the porous matrix (inset of FIG. 21C)

[00133] The crystalline nature of the porous particle matrices explains previous observations of their unchanged composition throughout REEs recovery leaching treatments. Crystalline aluminosilicates possess fewer interstices than their amorphous counterparts, such that reactions with leaching solutions are primarily restricted to solid-fluid interfaces (as opposed to solid-state transport in the case of amorphous matrices). Consequently, REE-bearing minerals in porous matrices are recovered via fluid transport through intraparticle pores, while the polycrystalline aluminosilicate matrix remains unaltered (FIG. 19B). A potential advantage of the less reactive polycrystalline matrices is minimal depletion of reagents in parasitic reactions with the bulk ash matrix and, subsequently, reduced contaminants released into the leaching solution. Specifically, REEs recovered from crystalline porous matrices are expected to yield lower levels of secondary metals (e.g., Al, Ca, Mg, Na, K) in the effluent solutions, reducing the separation requirements in downstream operations.

[00134] The potential for lower reagent consumption and purer effluents suggests that ash samples with a greater degree of porosity and crystallinity may provide a more efficient path for REEs extraction. As discussed earlier, the physiochemical properties of porous ash particles suggest that they originate from clays and have maintained their crystalline structures as a result of limited exposure to combustion. Amorphous matrices formed from the rapid solidification of molten minerals, on the other hand, result from firing at high temperatures. Coal combustion temperatures and residence times, therefore, could be adjusted to reduce the amorphous content generated in the ash to improve overall REEs recovery efficiency, economics, and environmental impact.

[00135] This study presents a nanoscale structural characterization of REE- bearing minerals in the porous lamella (FIG. 21 D). TEM and STEM-EDS data show that the REE-bearing minerals in the porous matrix consist of REEs phosphate (i.e. , monazite) crystals (FIG. 21 E, FIGS. 27A-27B). The TEM analysis in this study showed that the monazite is comprised of nanosized (~ 100 nm) grains rather than one single mineral, suggesting that multiple monazite grains nucleated but failed to grow into a single crystal or that heat-induced fragmentation of the original single grain occurred. The presence of multiple nanosized REEs grains corroborates previous work indicating that REE-bearing minerals may occur at the nanometer scale and suggest greater surface availability for dissolution reactions.

Environmental Implications

[00136] Coal fly ash is uniquely positioned to serve as a sustainable source of REEs and reduce the environmental footprint associated with conventional mining. Specifically, repurposing ash for REEs recovery creates the opportunity to move the mining industry toward a circular economy, transforming waste products into valuegenerating assets and sparing virgin mining locations. Adding coal ash to the supply chain of REEs will, however, require the development of extraction processes that are efficient and produce low levels of chemical waste.

[00137] This study highlights how the crystallographic structure of REE-hosting ash particles plays an important role in the release of REEs and secondary cations from fly ash. Specifically, dense aluminosilicate particles are comprised of amorphous matrices that, although enabling the transport of reagents and subsequent release of REEs, require reagent-intensive treatments and are expected to release contaminant metals. Crystalline porous particles, in contrast, possess less reactive matrices and, consequently, are expected to enable REEs recovery with lower reagent consumption associated with secondary reactions. These results provide valuable insights into the controls of REEs release at fundamental scales and are expected to inform the design of more efficient REEs extraction methods.

[00138] The claims are not intended to include, and should not be interpreted to include, means-plus- or step-plus-function limitations unless such a limitation is explicitly recited in a given claim using the phrase(s) “means for” or “step for,” respectively.

[00139] In view of the described processes and compositions, hereinbelow are described certain more particularly described aspects of the inventions. These particularly recited aspects should not, however, be interpreted to have any limiting effect on any different claims containing different or more general teachings described herein or that the “particular” aspects are somehow limited in some way other than the inherent meanings of the language and formulas literally used therein.

EXEMPLARY ASPECTS

[00140] Example 1 . A method comprising: evaluating a sample of a source comprising a plurality of particles to determine a spatiochemical type of at least a portion of the plurality of particles, wherein the plurality of particles comprise a first quantity of one or more critical minerals, wherein the evaluating comprises at least one of: imaging the at least a portion of the plurality of particles; analyzing a chemical composition of the at least a portion of the plurality of particles; measuring of an internal connected surface area of the at least a portion of the plurality of particles; or steps of both i) and ii), or i) and iii), or ii) and iii), or i), ii), and iii); quantifying a distribution of particles within the at least a portion of the plurality of particles based on the determined spatiochemical type; and adjusting a recovery of the one or more critical minerals based on the determined spatiochemical type.

[00141] Example 2. The method of any examples herein, particularly example 1 , wherein the source comprises coal ash.

[00142] Example 3. The method of any examples herein, particularly examples 1 or 2, wherein the plurality of particles further comprise a second quantity of one or more of Si, Al, Ca, Fe, Mg, Na, K, or any combination thereof. [00143] Example 4. The method of any examples herein, particularly examples 1-

3, wherein the step of imaging comprises scanning electron microscopy (SEM), transmission electron microscopy (TEM), or any combination thereof.

[00144] Example 5. The method of any examples herein, particularly examples 1-

4, wherein the step of analyzing the chemical composition comprises measurements by Energy Dispersive X-Ray composition analysis (EDX), Inductively Coupled Plasma analysis (ICP), X-Ray Fluorescence analysis (XRF), X-Ray Diffraction analysis (XRD), electron-probe micro analyzer (EPMA), or any combination thereof.

[00145] Example 6. The method of any examples herein, particularly examples 1-

5, wherein the spatiochemical type comprises a plurality of dense particles, a plurality of at least partially permeable particles, or a combination thereof.

[00146] Example 7. The method of any examples herein, particularly example 6, wherein at least a first portion of the first quantity of one or more critical minerals is disposed within at least a portion of the plurality of dense particles, or within at least a portion of the plurality at least partially permeable particles or a combination thereof.

[00147] Example 8. The method of any examples herein, particularly examples 6 or 7, wherein at least a second portion of the first quantity of one or more critical minerals is surface bounded to one or more of discrete particles of the plurality of particles.

[00148] Example 9. The method of any examples herein, particularly examples 1- 8, wherein the recovery step comprises an extraction step.

[00149] Example 10. The method of any examples herein, particularly example 9, wherein the extraction step comprises an acid leaching step, wherein an acid comprises one or more of HF, H2SO4, HNO3, HCI, or any combination thereof.

[00150] Example 11 . The method of any examples herein, particularly examplelO, wherein the acid has a concentration from about 0.1 M to full-strength.

[00151] Example 12. The method of any examples herein, particularly examples 9- 11 , wherein the extraction comprises heating to a temperature from about 20 °C to about 160 °C. [00152] Example 13. The method of any examples herein, particularly examples

10-12, wherein the acid leaching step has a duration from about 1 min to about 12 months.

[00153] Example 14. The method of any examples herein, particularly examples

11-13, wherein the adjusting step comprises selecting the acid at a predetermined concentration.

[00154] Example 15. The method of any examples herein, particularly examples

12-14, wherein the adjusting step comprises selecting the temperature of the acid leaching step.

[00155] Example 16. The method of any examples herein, particularly examples 12-15, wherein the adjusting step comprises adjusting the duration of the acid leaching step.

[00156] Example 17. The method of any examples herein, particularly examples 3- 16, further comprises extracting of the one or more of Si, Al, Ca, Fe, Mg, Na, K, or any combination thereof from the source.

[00157] Example 18. The method of any examples herein, particularly example 17, further comprises separating the one or more of critical minerals from the one or more of Si, Al, Ca, Fe, Mg, Na, K, or any combination thereof.

[00158] Example 19. The method of any examples herein, particularly examples 1-

18, wherein the recovery step comprises recovery from greater than 0% to 100% of the first quantity of the one or more critical minerals.

[00159] Example 20. The method of any examples herein, particularly examples 3-

19, wherein the recovery step comprises recovery from greater than 0% to 100% of the second quantity of the one or more of Si, Al, Ca, Fe, Mg, Na, K, or any combination thereof.

[00160] Example 21. The method of any examples herein, particularly examples 1-

20, wherein the one or more critical minerals comprise one or more rare earth metals comprising Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, TM, Yb, Lu, or any combination thereof.

[00161] Example 22. A system for maximizing a recovery of one or more critical elements comprising: a) a sample comprising a plurality of particles comprising one or more critical elements; b) an imaging device; c) at least one analyzing device; and d) an extraction apparatus; wherein the system is configured: to evaluate a spatiochemical type of at least a portion of the plurality of particles; to quantify a distribution of particles within the at least a portion of the plurality of particles based on the determined spatiochemical type; and to provide a path for maximizing the recovery of the one or more critical minerals based on the determined spatiochemical type.

[00162] Example 23. The system of any of one of examples herein, particularly example 22, wherein the sample comprises coal ash.

[00163] Example 24. The system of any one of examples herein, particularly examples 22 or 23, wherein the one or more critical elements are present in a first quantity.

[00164] Example 25. The system of any one of examples herein, particularly examples 22-24, wherein the plurality of particles further comprises one or more of Si, Al, Ca, Fe, Mg, Na, K, or any combination thereof present in a second quantity.

[00165] Example 26. The system of any one of examples herein, particularly examples 22-25, wherein the imaging device comprises one or more of SEM, TEM, or any combination thereof.

[00166] Example 27. The system of any one of examples herein, particularly examples 22-26, wherein the at least one analyzing device comprises EDX, ICP, XRF, XRD, EPMA, or any combination thereof.

[00167] Example 28. The system of any one of examples herein, particularly examples 22-27, wherein the extraction apparatus is configured to hold an extraction acid solution comprising one or more of HF, H2SO4, HNO3, HCI, or any combination thereof.

[00168] Example 29. The system of any one of examples herein, particularly examples 22-28, wherein the extraction apparatus is configured to withstand temperatures of about 20 °C to about 160 °C for up to about 12 months. REFERENCES:

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