Electrothermal chlorination and carbochlorination systems and methods for selective metal recovery

Abstract

Metal recovery and separation systems and methods, more particularly, electrothermal chlorination (ETC) and electrothermal carbochlorination (ETCC) methods and systems for selective metal extraction, e.g., for the extraction of key metals from waste streams. Alternatively, other oxidizing agents, such as fluorine, bromine, or iodine, can be used in place of or in addition to chlorine. Furthermore, alternatively, other reducing agents, such as metal(0) (e.g., tin(0)) and H2 (e.g., H2 in argon, e.g., 1% to 5% H2 by volume in argon), can be used in place of or in addition to carbon. Embodiments of the present invention can utilize ETC for the selective recovery of In from ITO-containing waste, and ETC combined with ETCC for Ta recovery from capacitor waste.

Description

Related Applications

[0001] Cross-reference to related patent applications

[0001] This application is related to U.S. patent application Ser. No. 63 / 415,384, entitled "Metal Recovery And Separation Systems And Methods," filed on October 12, 2023, by James M. Tour et al., which is co-owned by the present owner and is incorporated herein in its entirety.

[0002] This application is also related to U.S. patent application Ser. No. 18 / 263,831, entitled "Ultrafast Flash Joule Heating Synthesis Methods And Systems For Performing Same," filed August 1, 2023, to James M. Tour et al. ("Tour's '831 Application"), which is a national stage application under U.S. § 371 of PCT patent application PCT / US22 / 14923, entitled "Ultrafast Flash Joule Heating Synthesis Methods And Systems For Performing Same," filed February 2, 2022, to James M. Tour et al., which claims priority to U.S. patent application Ser. No. 63 / 144,862, filed February 2, 2021. All of these patent applications are commonly owned by the present owner. The Tour '831 application is incorporated herein in its entirety. [Technical Field]

[0003] Technical Field

[0003] The present invention relates to metal recovery and separation systems and methods, and more particularly to electrothermal chlorination and electrothermal carbochlorination methods and systems for selective metal extraction, e.g., for the extraction of metals of interest from waste streams.

[0004] Government Rights This invention was made with government support under Grant No. R1A330-416000 awarded by the United States Air Force Office of Scientific Research, Grant No. W912HZ-21-2-0050 awarded by the United States Engineer Research and Development Center for the United States Army Corp of Engineers, and Grant No. HR00112290122 awarded by the Defense Advanced Research Projects Agency, United States Department of Defense. The government has certain rights in this invention. [Background technology]

[0005] There is an urgent and increasing demand for metals for applications in electronics, superalloys, and renewable energy systems [Reck 2012; Sovacool 2020]. Metals are, in principle, infinitely recyclable. However, current metal recycling is often inefficient due to limitations in social behavior, product design, and recycling technologies. Recovering critical elements from electronic waste (e-waste), a class of urban mine, is important for a circular economy by simultaneously preventing disruptions to the supply chain of critical materials while reducing the environmental impact of waste disposal. It is estimated that more than 45 million tons of e-waste are produced each year, growing at approximately 9% annually [Ghosh 2015]. E-waste is becoming a huge environmental problem due to its heavy metal and plastic content [Ogunseitan 2009]. However, e-waste is also a valuable resource due to its high content of valuable metals [Chauhan 2018], including base metals (e.g., Cu, Al, and Fe), precious metals (e.g., Au, Ag, and Pt), rare earth metals (Sc, Y, and La groups), and critical metals (e.g., Ga, In, Ta) that are essential to the electronics platform but are currently difficult to obtain due to political and economic restrictions.

[0006]

[0006] Important metals such as Ga, In, and Ta have wide applications in semiconductor, display, and capacitor technologies and are therefore essential for modern electronics. For example, tantalum (Ta) is widely used as a tantalum capacitor in mobile phones and computers [Matsuoka 2004]. Ta production rates are limited, causing the price of Ta to skyrocket. Therefore, the recovery of Ta from e-waste is essential to achieving a sustainable Ta supply chain. For Ga, its production is estimated to be approximately 270 tons in 2012 [Salazar 2013].

[0007]

[0007] Ga is traditionally recovered from by-products of alumina and zinc production [Dutrizac 2000; Fang 1996]. The growing demand for Ga necessitates the search for new sources and extraction methods. Ga is used as a semiconductor in electronics, mostly in the form of gallium arsenide (GaAs), and also in some forms of gallium nitride (GaN), aluminum gallium indium phosphide (AlGaInP), and aluminum gallium arsenide (AlGaAs), among others. The recovery of Ga from e-waste is expected to compensate for the increasing consumption of Ga in consumer electronics.

[0008]

[0008] Indium, also a rare metal, is mostly recovered from by-product residues during the production of lead and zinc. Currently, In is mostly used to produce indium-tin-oxide (ITO) thin films, which are a key component of transparent electrodes in displays, touchscreens, photovoltaic cells, and smart windows because they are both transparent and conductive. As demand for personal electronics increases, In consumption is rapidly increasing. Therefore, recovery of In from consumer electronics scrap is important for a sustainable In supply chain.

[0009] Chlorination processes are used in extractive metallurgy for metal separation and are industrially used to separate titanium (Ti) from its ores [Jena 1997]. Various metals or metal compounds are reacted with a chlorinating agent to form metal chlorides, and differences in properties such as volatility and solubility of the metal chlorides enable the separation of the metals [Xing 2020]. Commercially, chlorination is performed using a fluidized bed [Niu 2013], which typically operates at 900–1300°C [Gleser '353 Patent]. The available temperature range limits its widespread application. As a result, the chlorination process is only applicable to a few scenarios, such as Ti and magnesium (Mg) [Xing 2020]. In addition, the inert heating and cooling processes inevitably reduce the efficiency of the chlorination process.

[0010] Similarly, rare earth elements (REEs) are important materials in modern electronics, clean technology, alloys, and catalysts [Cheisson 2019]. Aqueous acid leaching of concentrated REE minerals followed by two-phase solvent extraction remains the predominant scheme for bulk REE production [Cheisson 2019]. Although REE minerals are not ubiquitous, their individual separation remains extremely difficult. Mining from natural ores presents several challenges: (1) low-value mixed rare earth concentrates containing 60–70% Ce and La are produced, both of which have near-zero value and prevent the isolation of more desirable and important REEs such as Nd, Pr, Dy, Tb, and Sc; (2) iron, silicon, and aluminum oxides prevent high recovery rates and clean products; and (3) co-enrichment of actinides is highly challenging. While uranium (U) can be sold, thorium (Th) is produced at a 3:1 ratio compared to U. In the United States, enrichment of Th and U above certain levels is illegal. Back-blending into tailings is an environmental burden. It would be important if the process could recover the lanthanides while leaving the actinides in the feed, but there is currently no such solution.

[0011] It would therefore be highly advantageous if a technique could selectively recover Nd, Pr, Dy, Tb and Sc, while leaving behind Ce and La, as well as actinides and other impurities.

[0012]

[0012] REE separation is generally classified as primary separation (separation of REEs from other impurity elements) and secondary separation (separation of individual REEs) [Xie 2014]. The presence of metal impurities in REE-containing leachates affects the efficiency of subsequent REE separation by methods such as solvent extraction and ion exchange [Xie 2014; Judge 2020; Zhang 2021]. Therefore, impurities usually need to be removed prior to REE separation [Judge 2020].

[0013]

[0013] The composition of ores and secondary wastes often varies significantly from source to source, and therefore the impurities in leachate also vary significantly in type and content. [Judge 2020] Major impurities include Al, Si, Fe, Ca, Mg, Zn, Co, Ni, Cr, and Cu, among others. Many techniques, such as solvent extraction, ion exchange or adsorption, and selective precipitation, have been widely used to remove impurities from leachate solutions. [Judge 2020] Applicable routes depend significantly on the type and content of the impurities and the intended use of the REEs. For example, in the case of Fe-containing solutions, acidic extractants such as di(2-ethylhexyl)phosphoric acid (D2EHPA) can selectively extract REEs at appropriate extractant concentrations and organic / aqueous ratios. [Ye 2019] In the case of Al impurities, significant amounts can be removed through selective precipitation by adjusting the pH of the leachate solution. [Silva 2019] Ca and Mg impurities are usually not co-extracted with REEs, and the allowable upper limit is 1500 ppm [Li 2019]. Therefore, Ca and Mg are not a particular problem in REE extraction. In the case of Cu and Zn, they are usually not co-extracted with REEs by cation solvent extraction or ion exchange [Li 2019; Lou 2019].

[0014]

[0014] Regarding secondary separation, ion exchange or solvent extraction is the most suitable commercial technology for REE separation [Gupta 1992]. Because the chemical properties of rare earth ions in aqueous solution are similar, the degree of separation in solvent extraction processes is often very insufficient, typically with a separation factor of only 2-10 per stage [Adachi 1999]. Therefore, to achieve the required separation and purity of REEs, up to hundreds of stages of mixers and settlers may be assembled [Xie 2014]. In addition, the ion exchange process is not suitable for industrial production because it requires a very long period of time for significant separation [Uda 2000]. [Prior art documents] [Patent documents]

[0015]

Patent Document 1

Non-licensed literature

[0016]

Non-licensed literature 1

Non-licensed Document 4

Non-licensed Document 5

Non-licensed Document 6

[0017]

[0015] The present invention relates to metal recovery and separation systems and methods, and more particularly to electrothermal chlorination and electrothermal carbochlorination methods and systems for selective metal extraction, e.g., for the extraction of metals of interest from waste streams. [Means for solving the problem]

[0018] In general, in one embodiment, the invention features a method for selectively recovering at least one of two or more metals from a material. The method includes combining the material with an oxidizer to form a mixture. The material includes two or more metals. The method further includes subjecting the mixture to a flash joule heating process. The method further includes separating and selectively recovering at least one or more first metals of the two or more metals from at least one or more second metals of the material.

[0019] Implementations of the invention may include one or more of the following features. The oxidizing agent may be selected from the group consisting of chlorine agents, fluorine agents, bromine agents, iodine agents, and combinations thereof.

[0020] The oxidizing agent may include a chlorine agent. The chlorine agent may be selected from the group consisting of halogen salts, ammonium chloride, and combinations thereof.

[0021] The chlorine agent may be sodium chloride.

[0022] The chlorine agent may be Cl2.

[0023] The flash joule heating process may include an electrothermal chlorination process.

[0022]

[0024] The flash joule heating process may be carried out at a temperature between 630°C and 830°C.

[0025] The one or more first metals can include In.

[0023]

[0026] The flash heating process may be carried out at temperatures above 1240°C.

[0027] The one or more first metals may include a metal selected from the group consisting of Sn and Mn. The one or more second metals may include a metal selected from the group consisting of Au and Cr.

[0024]

[0028] The step of subjecting the mixture to a flash joule heating process may include subjecting the mixture to a first flash joule heating process at a first temperature to form a first product. The step of subjecting the mixture to a flash joule heating process may include subjecting the first product to a first evaporation process to form a first residue product. The step of subjecting the mixture to a flash joule heating process may include subjecting the first residue product to a second flash joule heating process at a second temperature.

[0025]

[0029] The second temperature may be higher than the first temperature.

[0030] The first flash joule heating process may include a first electrothermal chlorination process. The second flash joule heating process may include a second electrothermal chlorination process.

[0026]

[0031] The first flash joule heating process may be carried out at a temperature between 630°C and 830°C. The second flash joule heating process may be carried out at a temperature above 1240°C.

[0027]

[0032] The first evaporative process can form an evaporative phase.

[0033] The evaporable phase may include an In-containing compound.

[0034] The first residue product may include compounds containing a metal selected from the group consisting of Sn, Mn, Au, and Cr.

[0028]

[0035] A second flash joule heating process can form a second product.

[0036] A second evaporation process can be performed on the second product to form a second residue product.

[0029]

[0037] The second residue product may include a compound containing a metal selected from the group consisting of Au and Cr.

[0038] The second evaporation process can form a second evaporation phase.

[0030]

[0039] The second vaporizable phase may include a compound containing a metal selected from the group consisting of Sn and Mn.

[0040] The step of subjecting the mixture to a flash joule heating process may include a second flash joule heating process to form a second residue product. The step of subjecting the mixture to a flash joule heating process may include subjecting the second product to a second evaporation process to form a second residue product. The step of subjecting the mixture to a flash joule heating process may include subjecting the second residue product to a third flash joule heating process at a third temperature.

[0031]

[0041] The second temperature may be higher than the first temperature. The third temperature may be higher than the second temperature.

[0042] The material may be waste material.

[0032]

[0043] The waste material may be post-consumer electronic waste.

[0044] The waste may be industrial waste.

[0045] The industrial waste may be selected from the group consisting of coal fly ash, bauxite residue, ore, mining tailings, and dredge mud.

[0033]

[0046] The e-waste may include indium-tin oxide (ITO).

[0047] The waste material may be electrode waste.

[0048] The electrode waste may include compounds selected from the group consisting of In2O3, SnO2, Au, MnO, Cr2O3, and combinations thereof.

[0034]

[0049] The mixture may further comprise a reducing agent.

[0050] The reducing agent can be selected from the group consisting of a carbon source, a metal(0) source, H2, and combinations thereof.

[0035]

[0051] The reducing agent may include a metal(0) source.

[0052] The metal(0) source may include a tin(0) source.

[0053] The reducing agent may include H2.

[0036]

[0054] The reducing agent may include H2 in argon or nitrogen (N2).

[0055] The reducing agent may include 1% to 5% H2 by volume in argon or nitrogen (N2).

[0037]

[0056] The reducing agent may include a carbon source.

[0057] The flash joule heating process may include an electrothermal carbochlorination process.

[0038]

[0058] A flash joule heating process can form a first product. A first evaporation process can be performed on the first product to form a first residue product. The method can further include mixing a reducing agent with the first residue product to form a second mixture. The method can further include performing a second flash joule heating process on the second mixture.

[0039]

[0059] Prior to performing the second flash joule heating process, the method can perform a treatment on the first residue product. The treatment can be selected from the group consisting of an aqueous treatment, an aqueous acid treatment, and an aqueous base treatment.

[0040]

[0060] Treatment of the first residue product may increase the purity of one or more metals recovered from the first residue product.

[0061] The reducing agent can be selected from the group consisting of a carbon source, a metal(0) source, H2, and combinations thereof.

[0041]

[0062] The reducing agent may include a metal(0) source.

[0063] The metal(0) source may include a tin(0) source.

[0064] The reducing agent may include H2.

[0042]

[0065] The reducing agent may include H2 in argon or nitrogen (N2).

[0066] The reducing agent may be 1% to 5% H2 by volume in argon or nitrogen (N2).

[0043]

[0067] The reducing agent may include a carbon source.

[0068] The flash joule heating process on the mixture may comprise an electrothermal chlorination process. The second flash joule heating process on the second mixture may comprise an electrothermal carbochlorination process.

[0044]

[0069] The first evaporative process can form a first evaporative phase.

[0070] The first vaporizable phase may include a compound containing a metal selected from the group consisting of Fe, Ni, Mn, Cu, and combinations thereof.

[0045]

[0071] The first residue product may include compounds comprising a metal selected from the group consisting of Si, Ta, and combinations thereof.

[0072] A second flash joule heating process can form a second product.

[0046]

[0073] A second evaporation process can be performed on the second product to form a second residue product.

[0074] The second residue product may include compounds containing Ta.

[0047]

[0075] The second evaporation process can form a second evaporation phase.

[0076] The second vaporizable phase may include a compound containing Si.

[0077] The material may be waste material.

[0048]

[0078] The waste material may be post-consumer electronic waste.

[0079] The waste may be industrial waste.

[0080] The industrial waste may be selected from the group consisting of coal fly ash, bauxite residue, ore, mining tailings, and dredge mud.

[0049]

[0081] The waste may include Ta.

[0082] The waste may be capacitor waste.

[0083] The capacitor waste may include compounds selected from the group consisting of Fe2O3, NiO, MnO, CuO, SiO2, Ta2O5, and combinations thereof.

[0050]

[0084] The method is capable of selectively recovering at least one of two or more metals from a material with a selectivity of at least 70 wt% purity of the at least one metal.

[0085] The selectivity may be at least 90 wt%.

[0051]

[0086] The selectivity may be at least 95 wt%.

[0087] The selectivity may be at least 97 wt%.

[0088] The selectivity may be at least 99 wt%.

[0052]

[0089] The selectivity may be at least 99.999 wt%.

[0090] In general, in another embodiment, the invention features a system for selectively recovering at least one metal of two or more metals. The system includes a source of a mixture including a material and an oxidizer. The material includes two or more metals. The system further includes a cell operably connected to the source such that the mixture flows into the cell and is held under compression. The system further includes electrodes operably connected to the pressure cell. The system further includes a flash power supply for applying a voltage across the mixture to subject the mixture to a flash Joule heating process. The system is designed and operable to perform any of the methods described above, separating and selectively recovering at least one or more first metals of two or more metals of a material from at least one or more second metals of the two or more metals of the material.

[0053]

[0091] Implementations of the invention may include one or more of the following features.

[0092] The source of the mixture may include a material, an oxidizing agent, and a reducing agent.

[0054]

[0093] The system may include a second source comprising a reducing agent. [Brief explanation of the drawings]

[0055] [Figure 1A]

[0094] 1A-1H show the thermodynamics and setup of the electrothermal chlorination process. Figure 1A shows the critical reaction temperatures (Tcrit) for chlorination and carbochlorination for various metal oxides. [Figure 1B] FIG. 1B shows a schematic diagram of the electrothermal chlorination process in which metal chlorides or metal oxychlorides are vaporized and deposited on a quartz tube. [Figure 1C] Figure 1C shows the current profile at 60 V, a resistance of approximately 1 Ω, and a pulse duty cycle of 10%. The inset in Figure 1C is a zoomed-in current profile. [Figure 1D] FIG. 1D is a photograph of the carbon paper heater before (above) and during (below) electrical heating. [Figure 1E] Figure 1E shows the temperature profile of the carbon paper heater under different voltage inputs. [Figure 1F] Figure 1F shows the maximum temperature and heating / cooling rate of the carbon paper heater under different voltage inputs. [Figure 1G] Figure 1G shows the simulated average temperature profile of the sample and gas. The inset in Figure 1G shows the simulated cross-sectional temperature distribution at t = 0.6 s and 4 s. [Figure 1H] FIG. 1H shows the correlation of sample and gas temperatures with the carbon paper heater temperature (Theater). [Figure 2]

[0095] Figure 2 is a scheme of the electrothermal chlorination and carbochlorination system. [Figure 3A]

[0096] 3A and 3B show a power supply system, and Fig. 3A shows an electrical circuit diagram of the system. [Figure 3B] FIG. 3B shows an illustration of the power supply system. [Figure 4A]

[0097] 4A-4B show the geometry and boundary conditions for the simulations: Figure 4A shows the 3D framework of the simulation setup. [Figure 4B] Figure 4B shows a cross section of the simulation. [Figure 5]

[0098] Figure 5 shows the simulated temperature distribution at different times ranging from 0.1 seconds to 4 seconds. [Figure 6]

[0099] Figure 6 shows the simulated temperature distribution at t = 4 seconds under different carbon heater temperatures (Theater). [Figure 7A]

[0100] Figures 7A-7I show the selective recovery of In from ITO-containing waste. Figure 7A shows the calculated ΔG versus temperature for the chlorination of In2O3 and SnO2. [Figure 7B] FIG. 7B shows the maximum temperature (Tmax) versus voltage input for the carbon paper heater at a 5% duty cycle. [Figure 7C] FIG. 7C is a photograph of the ITO source material (bottom), volatiles (middle), and residue (top). [Figure 7D] FIG. 7D shows the Raman spectra of the ITO raw material, the InCl 3 volatile product, and the SnO 2 residue. [Figure 7E] Figure 7E shows the XRD patterns of the ITO raw material (PDF#01-089-4597), the InCl volatile product (PDF#01-0170), and the SnO residue (PDF#00-021-1250). [Figure 7F] FIG. 7F shows the purity and yield of the product versus the voltage input. [Figure 7G] Figure 7G shows the major metal compositions in the TCE waste. [Figure 7H] Figure 7H shows the ΔG of the chlorination reactions versus temperature for the major components in TCE waste, including In2O3, MnO, SnO2, Au, and Cr2O3. The dashed line indicates ΔG = 0 kJ mol-1. [Figure 7I] Figure 7I shows the recovery yield and purity of In from TCE waste. Error bars in Figures 7F, 7G, and I represent standard deviations for N=3. [Figure 8]

[0101] Figure 8 shows the temperature profile of the carbon paper heater under different voltage inputs. [Figure 9A]

[0102] Figures 9A-9B show the chlorination of In2O3 by the ETC process. Figure 9A shows a photograph of the In2O3 source material (bottom) placed on a carbon paper heater and the InCl3 volatiles deposited on a quartz tube. [Figure 9B]FIG. 9B shows the Raman spectra of the In2O3 raw material, commercial InCl3, and the as-obtained InCl3 volatiles. [Figure 10]

[0103] Figure 10 shows the protocol for the separation of In from TCF waste. [Figure 11A]

[0104] 11A-11B show the separation of In from TCF waste by the ETC process. Figure 11A shows the elemental composition of the raw material and volatiles under different voltage inputs. [Figure 11B] FIG. 11B shows the elemental composition of the raw material and residue under different voltage inputs. [Figure 12A]

[0105] 12A to 12I show the selective recovery of Ta from Ta capacitor waste. Figure 12A shows the main metals present in Ta capacitor waste. [Figure 12B] FIG. 12B shows the ΔG of the chlorination reaction of major metals in Ta capacitor waste, including Ta2O5, SiO2, CuO, Fe2O3, NiO, and MnO, versus temperature. [Figure 12C] FIG. 12C shows the ΔG of the carbochlorination reaction of Ta2O5 and SiO2 versus temperature. [Figure 12D] Figure 12D shows the kinetics of carbochlorination of Ta2O5 and SiO2. The slope of the Arrhenius fitted curve is the activation energy of the reaction, which is 53.6 kJ mol-1 for SiO2 and 31.6 kJ mol-1 for Ta2O5. [Figure 12E] Figure 12E shows EDS spectra of the first step volatiles (bottom) and the second step volatiles (top). The inset in Figure 12E is a photograph of the volatiles concentrated on the quartz tube, with the bottom inset being step 1 chlorination and the top inset being step 2 carbochlorination. [Figure 12F] FIG. 12F shows the percentage of metal content in the Ta capacitor raw material, step 1 volatiles and residue, and step 2 volatiles and residue. [Figure 12G]Figure 12G shows the purity and yield of the product under different electrothermal chlorination and carbochlorination conditions. The first row shows the ETC parameters for the first step, and the second row shows the ETCC parameters for the second step. [Figure 12H] Figure 12H shows the XRD patterns of the deposited volatiles and the volatiles after calcination. The reference PDF for Ta2O5 is shown (01-082-9637). [Figure 12I] Figure 12I shows the Raman spectra of the Ta2O5 raw material, the deposited volatiles, and the volatiles after calcination. The error bars in Figures 12A and 12G represent the standard deviation for N=3. [Figure 13A]

[0106] Figures 13A-13B show the chlorination of Ta2O5 by the ETC process. Figure 13A shows photographs of the Ta2O5 raw material (bottom) and the sample after chlorination. [Figure 13B] FIG. 13B shows the XRD pattern of the residue after the ETC process. [Figure 14A]

[0107] Figures 14A-14C show the carbochlorination of Ta2O5 by the ETCC process. Figure 14A shows a photograph of the mixture of TaO5 and C (bottom) and the volatiles deposited on the quartz tube after the ETCC process. [Figure 14B] FIG. 14B shows the XRD patterns of the volatiles deposited on the quartz tube and after calcination at 800° C. [Figure 14C] FIG. 14C shows the Raman spectra of the Ta2O5 raw material, the deposited volatiles, and the volatiles after calcination. [Figure 15A]

[0108] Figures 15A-15C show the carbochlorination of a mixture of Ta2O5 and SiO2 by the ETCC process. Figure 15A shows photographs of the mixture of Ta2O5, SiO2, and C (bottom) and the volatiles deposited on the quartz tube (top) after the ETCC process. [Figure 15B] FIG. 15B shows the XRD patterns of the volatiles deposited on the quartz tube and the volatiles after calcination. [Figure 15C]FIG. 15C shows the Raman spectra of the Ta2O5 raw material, the deposited volatiles, and the sample after calcination. [Figure 16]

[0109] Figure 16 shows a protocol for the separation of Ta from Ta capacitor waste by a two-step ETC and ETCC process. Note that a short rinse step with water before step 2 can remove small amounts of residual metal chlorides from the desired Ta2O3 and SiO2. [Figure 17A]

[0110] Figures 17A-17E show the characterization of ETC volatiles and residues from the first step. Figure 17A shows the XRD patterns of the TCW raw material, residue, and volatiles. [Figure 17B] FIG. 17B shows the EDS spectrum of the residue. [Figure 17C] FIG. 17C shows the EDS spectrum of the volatiles. [Figure 17D] FIG. 17D shows an SEM image and EDS elemental map of the residue. [Figure 17E] FIG. 17E shows an SEM image and EDS elemental map of the volatiles. [Figure 18A]

[0111] Figures 18A-18C show the characterization of the ETCC residue from the second step: Figure 18A shows the XRD pattern of the residue. [Figure 18B] FIG. 18B shows the EDS spectrum of the residue. [Figure 18C] FIG. 18C shows an SEM image and EDS elemental map of the residue. [Figure 19A]

[0112] Figures 19A-19F show the scaling rules and scale-up demonstration. Figure 19A shows photographs of carbon paper heaters with sizes of 2 × 6 cm, 3 × 9 cm, and 4 × 12 cm (W / L) (S = 2, 3, and 4, respectively) under the same voltage input of 100 V. [Figure 19B] Figure 19B shows the carbon paper heater temperature map versus voltage input and carbon heater length. The aspect ratio of the carbon paper heater is fixed at 3. [Figure 19C] Figure 19C shows the simulated average temperature profiles of samples with different carbon heater scales. The carbon heater temperature is fixed at 1200°C. The inset in Figure 19C shows the simulated temperature distributions for S = 2 and 4. [Figure 19D] FIG. 19D shows the sample mass as a function of time for T99 and the scale of the carbon paper heater. [Figure 19E] FIG. 19E shows photographs of untreated capacitor waste placed on a carbon heater with a size of 3 × 9 cm (top) and volatile materials deposited on a quartz tube after the second-step ETCC reaction (bottom). [Figure 19F] FIG. 19F shows the purity and yield of the Ta product recovered from the scaled-up batch. [Figure 20]

[0113] Figure 20 shows the simulation of temperature distributions at different scales at t = 4 seconds for the 2D scale-up case. The carbon paper heater temperature is fixed at 1200 °C. [Figure 21]

[0114] Figure 21 shows the simulated temperature distribution of the upscale sample (S=4) at different times varying from 1 second to 60 seconds. The carbon heater temperature is fixed at 1200°C. [Figure 22A]

[0115] Figures 22A-22C show a 3D scale-up of the ETC process: Figure 22A shows the simulated temperature distribution at different scales. [Figure 22B] Figure 22B shows the simulated average temperature profile of the sample at different carbon heater scales. The carbon paper heater temperature is fixed at 1200°C. [Figure 22C] FIG. 22C shows the normalized sample mass as a function of time and carbon heater scale for T99. [Figure 23A]

[0116] Figures 23A-23B show the scale-up of the ETC process for In separation from ITO. Figure 23A shows a photograph of the ITO raw material (top) and the volatiles deposited on the quartz tube (bottom). [Figure 23B] FIG. 23B shows the purity and yield of the In product in different batches. [Figure 24A]

[0117] Figures 24A-24F show the scale-up of a two-step process for Ta recovery from TCW. Figure 24A shows photographs of the TCW feedstock (top) and the volatiles (bottom) deposited on a quartz tube resulting from the first-step chlorination process. [Figure 24B] FIG. 24B shows a photograph of the mixture of residue and C from the first step (top) and the volatiles deposited on the quartz tube obtained from the second step carbochlorination process (bottom). [Figure 24C] FIG. 24C shows the XRD patterns of the second step deposited volatiles and the volatiles after calcination. [Figure 24D] FIG. 24D shows the Raman spectra of the second step deposited volatiles and the volatiles after calcination. [Figure 24E] FIG. 24E shows the EDS spectrum of the deposited volatiles from the second step. [Figure 24F] FIG. 24F shows an SEM image and EDS elemental map of the volatiles. DETAILED DESCRIPTION OF THE INVENTION

[0056]

[0118] The present invention relates to metal recovery and separation systems and methods, and more particularly to electrothermal chlorination and electrothermal carbochlorination methods and systems for selective metal extraction, e.g., for the extraction of metals of interest from waste streams.

[0057]

[0119] "Selective" or "selectivity," as used herein, means that the method / system recovers and separates a metal (or group of metals) into components having a purity of at least 70 wt% of the metal (or group of metals). In some embodiments, the selectivity may be at least 90 wt% purity, in further embodiments, the selectivity may be at least 95 wt% purity, in further embodiments, the selectivity may be at least 97 wt% purity, in further embodiments, the selectivity may be at least 99 wt% purity, and in still further embodiments, the selectivity may be at least 99.999% purity.

[0058] Electrothermal chlorination and carbochlorination

[0120] Embodiments of the present invention include innovative electrothermal chlorination and carbochlorination methods and systems for the selective extraction of critical metals from waste streams. These methods and systems utilize programmable pulsed current input to provide precise control over temperature and reaction duration during the chlorination process. This level of control can be utilized to achieve both thermodynamic and kinetic selectivity to desired metals. These methods and systems have broad applicability, such as selectively recovering indium tin oxide from waste tantalum capacitors and indium from tantalum-containing waste materials. Furthermore, these methods and systems are scalable. Due to their compact reactor design and rapid processing capabilities, these methods offer a variety of applications in metal recycling, purification, and process intensification.

[0059] Thermodynamics and setup

[0121] Thermodynamic analyses were performed on the chlorination of 34 metal oxides covering representative metals in the s, p, and d blocks using chlorine (Cl2) as the chlorinating agent. The thermodynamic analyses were performed using HSC Chemistry 10 software. The direct chlorination of metal oxides was investigated for the following reactions: MO x+xCl2=MCl 2x +x / 2O2(1)

[0122] The carbochlorination of metal oxides was investigated using the following reaction: MO x +xCl2+xC=MCl 2x +xCO (2)

[0123] Calculations were performed under a standard pressure of 1 atm. Thirty-four metal oxides covering representative metals in the s, p, and d blocks and their corresponding chlorides include Li2O / LiCl, Na2O / NaCl, K2O / KCl, BeO / BeCl2, MgO / MgCl2, CaO / CaCl2, B2O3 / BCl3, Al2O3 / AlCl3, Ga2O3 / GaCl3, In2O3 / InCl3, SiO2 / SiCl4, GeO2 / GeCl4, SnO2 / SnCl4, PbO / PbCl2, and TiO2 / TiCl 4, ZrO2 / ZrCl4, HfO2 / HfCl4, V2O5 / VCl5, Nb2O5 / NbCl5, Ta2O5 / TaCl5, Cr2O3 / CrCl3, MoO3 / MoCl5, WO3 / WCl6, MnO / MnCl2, Fe2O3 / FeCl3, CoO / CoCl2, NiO / NiCl2, PdO / PdCl2, PtO2 / PtCl2, CuO / CuCl2, Ag2O / AgCl, ZnO / ZnCl2, CdO / CdCl2, and HgO / HgCl2. The thermodynamic favorability of a direct chlorination reaction is considered first; if it is not favorable, a carbochlorination reaction is considered, in which carbon reduces the metal oxide to a lower valent metal oxide or metal(s) that can react with, for example, chlorine to form the desired metal chloride. Alternatively, other oxidizing agents, such as fluorine, bromine, or iodine, may be used in place of, or in addition to, chlorine. Furthermore, alternatively, other reducing agents, such as metal(0) (such as tin(0)) and H2 (e.g., H2 in argon or nitrogen (N2), such as 1% to 5% H2 by volume in argon or nitrogen (N2)) may be used in place of, or in addition to, carbon. Mixtures with less than 5% H2 in argon are safer because they are below the explosive limit of H2.

[0060]

[0124] These metals can be classified into several groups, as shown in Figure 1A, and the critical reaction temperatures (T crit ) indicates: (i) Direct chlorination is favored at all temperatures above 0°C: Li, Na, K, Ca, Pb, Co, Pt, Ag, Zn, Cd, and Hg.

[0061] (ii) Direct chlorination is only advantageous at temperatures above certain values ​​(lower limits): Mg (1870°C), Al (2220°C), Ga (875°C), In (630°C), Ge (1010°C), Sn (1250°C), Mn (830°C), Fe (1230°C), and Ni (1680°C).

[0062] (iii) Direct chlorination is only advantageous below certain values ​​(upper limits): Mg (460°C), Ni (870°C), Pd (1930°C), Cu (1370°C). (iv) Direct chlorination is not favored at any temperature: Be, B, Si, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W.

[0063] (v) Carbochlorination is favored at all temperatures above 0°C: Be, B, Si, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W.

[0125] Both the chlorination reaction equation (1) and the carbochlorination reaction equation (2) were calculated and these reactions can be categorized into four groups: (i) The chlorination reaction is favorable at all temperatures.

[0064] (ii) The chlorination reaction is favored at a lower temperature threshold. (iii) The chlorination reaction is favored at an upper temperature threshold. (iv) Chlorination reactions are not favored at all temperatures, but when carbon acts as a reducing agent and the reduced metal is reactive with chlorine, these carbochlorination reactions are favored.

[0065]

[0126] This analysis highlighted the limitations of conventional chlorination reactions. First, the temperatures required for chlorination reactions can range from 400 to 2400 °C, and therefore many metal oxides cannot be chlorinated using conventional heating methods, which generally operate below 1500 °C. Second, the reaction temperature difference is narrow between metal oxides, requiring precise temperature control to ensure selectivity based on reactivity differences. Third, for chlorination reactions with similar trends in reactivity, it is impossible to separate them simply based on thermodynamics.

[0066]

[0127] To address these obstacles, direct electrical heating may be utilized for electrothermal chlorination (ETC) or electrothermal carbochlorination (ETCC). See Figures 1B-1H; Figure 2. Unlike conventional furnaces, which heat samples via thermal convection, metal oxide precursors were placed on a carbon paper heater and heated via thermal conduction. As shown in Figures 3A-3B, an electrical system was used to deliver a programmable direct current (DC) to the carbon paper heater (Figure 1C), which allows for its rapid heating and cooling (Figure 1D). The temperature of the carbon paper heater can be precisely adjusted by varying the voltage input, achieving a wide temperature distribution from 400 to 2500 °C. Figure 1E (plots 101-108 are for 140 V, 120 V, 100 V, 80 V, 60 V, 50 V, 40 V, and 30 V, respectively) demonstrates this.

[0067]

[0128] Figures 3A-3B show a schematic of the electrical system for generating pulsed direct current. A capacitor bank capable of reaching a voltage of up to 500 V with a total capacitance of 0.624 F was used. The capacitors were charged by a DC power supply. A variable frequency drive (VFD) was used to generate the pulsed voltage with a frequency (f) ranging from 0 to 1000 Hz (f = 1000 Hz was typically used in the experiments described herein). The duty cycle (or ON state duration) was adjustable (a 5% or 10% duty cycle was typically used in the experiments described herein). The current profile was recorded using a multifunction I / O (NI USB-6009) controlled by LabView. Carbon paper fixed on a graphite block and connected to the electrical system via two graphite electrodes was used as a heater. For a 1 cm x 3 cm piece of carbon paper, the resistance was approximately 0.7 Ω, which is appropriate for Joule heating.

[0068]

[0129] The ETC process exhibits several unprecedented features that address the limitations of conventional furnace-heating-based chlorination processes. First, high temperatures up to 2500 °C allow the chlorination reaction of almost all metal oxides (Figure 1A), greatly expanding the applicability of the chlorination process. Second, precise temperature controllability by adjusting the voltage input of the electrothermal process (Figure 1F; plots 111–113 are plots of T, respectively) is possible. max , heating, and cooling) allows for the separation of metals in a narrow reaction window. Third, ultrafast heating (up to approximately 4500 °C·s -1 ) and cooling (approximately 500°C·sec -1 ) rates (Figure 1F) allow the use of reaction kinetic selectivity based on reaction rates and activation energy differences between thermodynamically similar reactions.

[0069]

[0130] In the electrothermal chlorination setup, metal oxide precursors and Cl gas were heated by a carbon paper heater. Simulations were performed to evaluate the details of the sample and gas heating process. The primary objective of this simulation was to evaluate how the sample and gas temperatures correlated with the carbon paper heater temperature. Numerical simulations were performed based on the finite element method (FEM) using the software COMSOL Multiphysics 5.5. Heat transfer at the solid-fluid interface in the heat transfer module was used in the time-dependent study. The geometric configuration, material parameters, and boundary conditions are shown in Figures 4A-4B and Tables I-II.

[0070] [Table 1]

[0071] [Table 2]

[0072]

[0131] The geometry of all components was similar to that of the actual experiment. The temperature of the quartz tube wall was set to 320 °C based on experimental measurements during the chlorination reaction. The temperature of the inlet gas was set to room temperature (20 °C), and the pressure was set to 1 atm. The Cl2 flow rate was estimated to be 10 sccm. The maximum temperatures of the carbon paper heater using voltage inputs of 60, 80, 100, 120, and 140 V (Figures 1E-1F) were experimentally measured. These values ​​were used as input values ​​for the carbon paper heater temperature, and time-dependent heater movement was performed for the simulation to obtain the temperature distribution. Simulations were performed at four scales (S) of 1, 2, 3, and 4. S = 1 represents the experimental conditions used mostly, while larger S represents upscaled experiments.

[0073]

[0132] The temperature of the carbon paper heater was measured experimentally under a voltage input of U=60V, T heater= 1141 °C (Figure 1F). The sample temperature is defined as the average temperature of the sample, and the gas temperature is defined as the average temperature of the gas within the diameter of the carbon paper, considering that only the gas close to the sample reacts. The sample and gas temperatures were found to reach a plateau (approximately 1141 °C) in approximately 4 seconds (Figure 1G (plots 121-122 for the sample and gas, respectively; dashed line 123 indicates the carbon paper heater temperature fixed at 1141 °C); Figure 5), demonstrating the rapid sample and gas heating capability of the electrothermal process. This differs from conventional indirect heating processes, which may require time to reach thermal equilibrium. In addition, T heater By varying the temperature of the sample and gas, T heater The close conformance of the temperature pattern (Figure 1H (plots 131-132 for sample and gas, respectively); Figure 6) provides precise controllability of the reaction temperature. (The sample and gas temperatures were found to closely follow the pattern of the carbon paper heater temperature.)

[0074]

[0133] In a typical small-scale experiment, a sample mass of 100 mg would require a 1 x 3 cm 2 A carbon paper size of 1000 nm was used. The sample was placed on a carbon paper heater connected to a capacitor bank. The sample was placed in a sealed quartz tube. After purging the system three times, Cl2 was introduced at a flow rate of approximately 20 sccm for small-scale samples and approximately 40 sccm for large-scale samples. A pulsed current input brought the carbon paper heater to the desired temperature. The sample and gas temperatures rapidly followed the heater pattern, as shown in Figure 1G. Volatiles were deposited on the quartz tube. Because chloride products are usually deliquescent, the sealed sample in the quartz tube was transferred to a glove box, where the sample was then collected. Table III lists the detailed experimental conditions for the experiment.

[0075] [Table 3]

[0076] Recovery of In from ITO-containing waste

[0134] The recovery of key metals in real wastes was then tested and exemplified by In recovery from ITO-containing wastes and Ta recovery from Ta capacitor wastes.

[0077]

[0135] Indium is an important metal and, because it has no minerals of its own, is commonly produced as a by-product from other metallurgical processes, particularly zinc (Zn) and copper (Cu) [Frenzel 2017]. In is considered an important element in technology and is primarily used as indium tin oxide (ITO), which serves as the primary waste stream for In recycling [Virolainen 2011]. ITO is composed of 90% In and 10% tin (Sn). The thermodynamics of the chlorination reactions of In2O3 and SnO2 using Cl2 as the chlorinating agent were analyzed. Figure 7A (plots 701-702 for the chlorination of In2O3 and SnO2, respectively, and dashed line 703 for ΔG = 0 kJ mol) -1 The temperature window of 630–1240°C allows the conversion of In2O3 to InCl3, while SnO2 remains unreacted.

[0078]

[0136] The InCl can then be evaporated as a volatile phase, thus separating InCl from SnO based on their difference in volatility. The above temperature window corresponds to a voltage input of 90-110 V. Figure 7B (plot 704 versus lower dashed line 705 and upper dashed line 706 show T = 630 °C and 1240 °C, respectively); Figure 8 (plots 801-805 versus 80 V, 90 V, 1000 V, 110 V, and 120 V, respectively).

[0079]

[0137] First, the feasibility of converting In2O3 to InCl3 by the ETC process was demonstrated by controlling the voltage input at 100 V (Figures 9A-9B). ITO was then used as the precursor. After the ETC process, volatile condensates were obtained on the quartz tube, and residues remained on the carbon paper heater (Figure 7C). X-ray diffraction patterns and Raman spectra indicated that the volatile material was InCl3 and the residue was SnO2. 。 Figures 7D-7E.

[0080]

[0138] The effect of voltage input on product purity and yield was investigated. Figure 7F (bars 711-712 are for purity and yield, respectively). As the voltage increased, yield improved due to a more complete reaction; however, excessive voltage input at 120 V resulted in significantly reduced purity due to simultaneous chlorination of SnO. Figure 7B. Optimized results exhibit 99% purity and 91% yield for the In product. Figure 7F.

[0081]

[0139] Next, we investigated the recovery of In from real waste transparent conductive films (TCFs). After removing the plastic substrate by calcination, a metal mixture was obtained, mainly consisting of Au, In, Sn, Mn, etc. Overall quantification showed that In accounted for approximately 30 wt% of the metal content (Figure 7G). Five metals, including Au, In, Sn, Mn, and Cr, were found to have a content greater than 1 wt%. Computational thermodynamic analysis of the chlorination reaction was performed for Au, In2O3, SnO2, MnO, and Cr2O3 (Figure 7H).

[0082]

[0140] The temperature window was 630°C–830°C, and only under these conditions could In2O3 be chlorinated and separated from other metals by evaporation (Figure 10). Because voltage is critical for In recovery, the effect of voltage on In recycling performance was investigated (Figure 7I; Figures 11A–11B). A relatively low voltage of 100 V resulted in an inappropriately low temperature, which could also chlorinate Au, resulting in low purity of the In product. A voltage that was too high (110 V) resulted in SnO2 and MnO being chlorinated and mixed with the desired In product. An appropriate voltage of 105 V resulted in an overall performance of 95% purity and 92% In yield (Figure 7I). This demonstrates the critical role of precise temperature control for selective metal recovery, a key advantage and benefit of electrothermal processes. All of this was possible without the use of water or acid, resulting in no tailings or secondary liquid waste.

[0083] Ta recovery from Ta-containing waste

[0141] Ta is a metal important to other technologies, primarily used as a capacitor in electronics and in superalloys [Agrawal 2021]. The annual global production of ta is approximately 2,000 tons, with 42% of the ta consumed in the manufacture of ta capacitors [Angerer 2013]. Waste ta capacitors are widely present in small electrical appliances and contain as much as 45 wt% ta, making them a high-grade ta resource [Niu 2017]. Here, ta capacitor waste (TCW) was subjected to calcination in air to remove the plastic and resin layers. A fine yellow powder composed of various metal oxides, including tantalum pentoxide (Ta2O5), was subsequently obtained. Total quantification of the metals in the powder was performed after digestion, followed by ICP-MS analysis. Figure 12A. The mass fraction of ta in the waste was approximately 37.8 wt%, and other major metal components (>1 wt%) included Si, Mn, Cu, Fe, and Ni.

[0084]

[0142] First, we analyzed the thermodynamics of the chlorination reaction of these metal oxides with Cl2 using a computer. Figure 12B (dotted line indicates ΔG = 0 kJ mol -1These metal oxides are classified into two groups. The first group includes CuO, Fe2O3, NiO, and MnO, whose chlorination reaction is thermodynamically favorable below a certain temperature threshold (an upper limit for CuO, and a lower limit for Fe2O3, NiO, and MnO). The second group includes Ta2O5 and SiO2, whose chlorination reaction is thermodynamically unfavorable.

[0085]

[0143] Experimental chlorination of Ta2O5 with Cl2 was performed and found to be non-reactive (Figures 13A-13B), in good agreement with the theoretical analysis. Therefore, for Ta2O5 and SiO2, the thermodynamics of their carbochlorination reactions were analyzed (Figure 12C, dotted line indicates ΔG = 0 kJ mol -1 ), which indicates that both are favorable in the investigated temperature range. Nevertheless, the large difference in Gibbs free energy change (ΔG) between SiO2 and Ta2O5 indicates a possible reaction kinetic selectivity for their separation.

[0086]

[0144] Experimentally, Ta2O5 was mixed with carbon (C) and an ETCC reaction was performed (Figures 14A-14C). Ta2O5 was successfully converted to volatile products, predicted to be tantalum oxychlorides, which could be collected via an evaporation-condensation process.

[0087]

[0145] Similarly, SiO2 can be converted to volatile products by the ETCC process. The carbochlorination reaction kinetics was measured and rate constants were obtained. For the following reaction: SiO2(s)+2Cl2(g)+2C(s)=SiCl4(g)+2CO(g) (3) Ta2O5(s)+5Cl2(g)+5C(s)=2TaCl5(g)+5CO(g) (4) By definition, the reaction rate (v) is defined as follows:

[0088]

number

[0089]

[0146] Experimentally, SiO2 (or Ta2O5) was mixed with C separately according to the stoichiometric ratio, and the carbochlorination reaction was carried out. By measuring the weight loss at different reaction times (Δt), the corresponding Δn(SiO2) (or Δn(Ta2O5)) was obtained. Then, the reaction rate was calculated.

[0090]

[0147] During the experiment, Cl was supplied in excess, and SiO, TaO, and C were solids; therefore, the above carbochlorination reaction can also be considered as a zero-order reaction. Therefore, the reaction rate constant (k) can be calculated as follows: k(SiO2)=v(SiO2) (7) k(Ta2O5)=v(Ta2O5) (8) Assuming that k is temperature independent, according to the Arrhenius equation, the rate constant as a function of reaction temperature (T) is given by:

[0091]

number

[0092] where A is the frequency factor and E a is the activation energy and R is the gas constant. Equation (9) can be modified as follows:

[0093]

number

[0094]

[0148] By plotting lnk~1 / T (Figure 12D, plots 1201-1202 for Ta2O5 and SiO2, respectively), the activation energy of the carbochlorination reaction is found to be E a (SiO2) = 53.6 kJ mol -1 and E a (Ta2O5) = 31.6 kJ mol -1 It was calculated that:

[0095]

[0149] The activation energy difference allows for the kinetically controlled separation of Ta2O5 and SiO2. To further confirm this, SiO2 and Ta2O5 were mixed with the addition of C and an ETCC reaction was performed (Figure 15A). By precisely controlling the voltage to 100 V and the corresponding temperature to approximately 1050 °C, Ta2O5 was selectively chlorinated and separated by evaporation from the remaining unreacted SiO2 (Figures 15B-15C).

[0096]

[0150] By exploiting thermodynamic and kinetic selectivity, a two-step process can be utilized for Ta separation from capacitor waste. Figure 16. In a typical experiment, the first step is the ETC reaction by controlling the electrothermal temperature at approximately 1230–1380 °C. CuO, Fe2O3, NiO, and MnO are converted to their chlorides and evaporated as a volatile phase. Characterization of the volatile phase by elemental dispersive spectroscopy (EDS, Figure 12E, bottom; Figures 17A–17E) and ICP-MS (Figure 12F, step 1 volatiles) showed that Cu, Fe, Mn, and Ni were enriched in the volatile components. In contrast, Ta and Si were unreactive and remained in the residue phase, as confirmed by EDS (Figures 17B and 17D) and ICP-MS (Figure 12F, step 1 residue). (At this point, an optional water rinse to remove small amounts of metal chlorides may be performed, but is not required.)

[0097]

[0151] Next, in the second step, the residue from the first step was mixed with carbon black (CB) and the reaction was carried out. By controlling the electrothermal temperature at approximately 1050 °C, most of the TaO was chlorinated and collected as a volatile phase by evaporation, as evidenced by EDS (Figure 12E, top) and ICP-MS (Figure 12F, step 2 volatiles). In contrast, most of the SiO remained in the residue phase (Figure 12F, step 2 residue; Figures 18A-18C). After optimizing the voltage input and duration of the two-step process, selective recovery of Ta from capacitor waste was achieved with 96% purity and 88% yield. Figure 12G (bars 1211-1212 correspond to the purity and yield at each of three different voltages or durations, respectively). The as-obtained Ta product was an amorphous mixture of tantalum oxychlorides, which could be easily converted to pure TaO by mild calcination in air. Figures 12H-12I.

[0098] Scale-up capability

[0152] The scalability of the electrothermal chlorination process was evaluated. Accurate temperature control can play a key role in the selective recovery of metals. Therefore, the parameters that determine the temperature were first investigated. Using the system shown in Figure 3B with the RC circuit of Figure 3A, analysis revealed that the heater resistance of the Joule heating plays a key role, and there is an optimal resistance for the carbon paper heater to achieve favorable energy conversion efficiency from electricity to heat. This value is determined by the power supply system, and for the system shown in Figure 3B, the optimized value was determined to be 0.5 Ω to 2 Ω.

[0099]

[0153] Therefore, when scaling up the present method and system, it may be important to maintain a consistent resistance of the carbon heater. This can be easily achieved by maintaining the heater's thickness and aspect ratio (defined as the ratio of length to width, L / W). The resistance of the carbon paper heater (R) is calculated by:

[0100]

number

[0101] where ρ is the resistivity of the carbon heater, and L, W, S, and D are the length, width, cross-sectional area, and thickness of the carbon heater, respectively.

[0154] If the D and aspect ratio (L / W) of the carbon paper heater are maintained, the resistance (R) of the carbon paper heater is expected to remain the same. For example, a 1x3cm 2 When a carbon paper heater size of 1901 is used (as in the small-scale experiments), this is denoted as a scaling factor (S) = 1. The resistance (R1) of this carbon paper heater is approximately 0.7 Ω. This process was upscaled to S = 2, 3, and 4, as shown in Figure 19A, for carbon paper heaters 1901-1903, respectively. (The carbon paper heaters 1901-1903 are 2 × 6 cm in size, respectively.) 2 , 3×9cm 2 , and 4 × 12 cm 2 (W / L). The resistance of these samples was the same according to experimental measurements, as expected. The temperatures of the carbon paper heaters with different scales were measured under different voltage inputs. Figure 19B. This temperature plot provides guidance on how to adjust the voltage input when scaling up.

[0102]

[0155] As studied through further simulations, when scaling up the sample size, the sample temperature was regulated by the heater temperature. Heat conduction from the carbon paper heater to the sample is determined by Fourier's law. Assuming the sample is at a uniform temperature during heating, the sample temperature at time t is T sample and the temperature gradient (θ) is θ=T sample -T heater (12) where T heateris the temperature of the carbon paper heater. Then, the temperature gradient at the initial time (θ0) is θ0=T sample,0 -T heater (13) where T sample,0 is the initial temperature of the sample.

[0103]

[0156] Following instantaneous heat transfer, the sample reaches T sample The time required to reach

[0104]

number

[0105] where ρ s is the density of the sample, and V s is the volume of the sample, and c s is the specific heat capacity of the sample, h is the heat transfer coefficient, and A s is the heat transfer area between the carbon paper heater and the sample.

[0106]

[0157] V s =D s ×A s (In the formula, D s is the thickness of the sample), the above equation (14) can be modified as follows:

[0107]

number

[0108]

[0158] T 99 The sample is heated to 99% of the carbon paper heater temperature (T sample =0.99T heater ) and the following equation is obtained:

[0109]

number

[0110]

[0159] Two scenarios were considered for upscaling: the first scenario was to scale up the sample in two dimensions (length and width, denoted as 2D scale-up), and the second scenario was to scale up the sample in three dimensions (length, width, and thickness, denoted as 3D scale-up).

[0111]

[0160] First, we considered two-dimensional (2D) scaling up. This means that the length and width of the sample are scaled up proportionally according to the dimensions of the carbon paper heater, while keeping the thickness of the sample the same. The temperature profiles of the sample at different scales follow a common pattern regardless of the scale (Figure 19C (overlapping plots 1911, S = 1, 2, 3, and 4, respectively); Figure 20).

[0112]

[0161] T 99 where t represents the time required to heat the sample to 99% of the carbon paper heater temperature and can be used to quantitatively describe the dependence of heating duration on sample scale. While the sample mass increases exponentially (Figure 19D, plot 1921), T 99 The time is independent of sample magnification (FIG. 19D, plot 1922), demonstrating the excellent scalability of electrical heating.

[0113]

[0162] Three-dimensional (3D) scale-up was then analyzed, meaning that all three dimensions of the sample were scaled up proportionally according to the dimensions of the carbon paper heater. In this case, with increasing sample scale, T 99 The time for which the sample mass is measured increases in phase with the sample mass. Figures 21 and 22A-22C. Figure 22B shows the simulated average temperature profile of the sample, plots 2201-2204 for different carbon heater scales S=1, 2, 3, 4, respectively. Figure 22C shows the T varying with carbon heater scale in plots 2211-2212, respectively.99 Figure 21 shows the time and normalized sample mass of the sample. Nevertheless, for the upscaled sample, the temperature plateaus in about 1 minute (Figure 21), which is still superior to indirect heating, which may take longer to reach thermal equilibrium. Essentially, for 3D scale-up, a longer heating period is found to be required for temperature equilibrium of larger S, and this period is determined by the heat transfer rate. The above results indicate that electrical heating is particularly superior for 2D scale-up.

[0114]

[0163] Furthermore, electrothermal chlorination was scaled up to the gram scale. A 2-inch (5.08 cm) tubular reactor was constructed, and a 9 cm x 3 cm (L / W) carbon paper heater was used. For ETC of In from ITO at the 1 g scale, a larger reactor was used (Figure 23A). The overall process is the same as for the small-scale reaction. After optimization, comparable 98% purity and 91% yield were achieved (Figure 23B (bars 2301-2302 for purity and yield, respectively, for three different batches)), which was almost the same as for the smaller reactor (Figure 19F (bars 1931-1932 for purity and yield, respectively)).

[0115]

[0164] A 10-minute processing time was required, corresponding to a productivity of 144 g / day. Scaling of the two-step ETC and ETCC process subsequently increased the selective recovery of Ta from Ta capacitor waste, also at a 1 g scale (Figures 19E and 24A-24F), achieving 95.1% purity, although yields were lower due to downstream losses. Further optimization is being performed by modifying the product collection system. In all cases, unreacted Cl can be recycled or reused via typical industrial methods.

[0116] Further Use

[0165] ETCs and ETCCs can be used for the selective separation and recovery of technology-critical metals from e-waste. Most methods simply extract many metals at once, relying on classical wet-chemical methods focused on water, acid, or base, resulting in tailings and toxic secondary waste streams. In embodiments of the present invention, all water and acid use is mitigated. Compared to traditional chlorination processes, the introduction of electrostatic charging broadens the scope of chlorination metallurgy by enabling advantages such as precise temperature control at ultra-high temperatures and the possibility of controlling reaction kinetics. Embodiments of the present invention can utilize ETCs for the selective recovery of In from ITO-containing waste and ETCs combined with ETCCs for Ta recovery from capacitor waste. Such methods and systems are scalable, and the utility of this approach for larger volumes is clear. By leveraging thermodynamic and kinetic selectivity in a compact reactor design, ETCs and ETCCs are also pioneering technologies for water- and acid-free metal recycling, purification, and price stabilization, while minimizing the need for continuous metal mining.

[0117]

[0166] Additionally, the present invention provides a system and method for metal recovery and separation, particularly a system and method for metal recovery and separation by combining a chloride process in a flash joule heating system and method.

[0118]

[0167] While embodiments of the present invention have been shown and described, modifications thereof can be made by those skilled in the art without departing from the spirit and teachings of the present invention. The embodiments described herein and examples provided are illustrative only and are not intended to be limiting. Many variations and modifications of the invention disclosed herein are possible and are within the scope of the present invention. The scope of protection is not limited to the above description, but is limited only by the following claims, which scope includes all equivalents of the subject matter of the claims.

[0119]

[0168] The disclosures of all patents, patent applications, and publications cited herein, to the extent that they provide exemplary, procedural, or other details supplementary to those set forth herein, are hereby incorporated by reference in their entireties.

[0120]

[0169] Quantitative and other numerical data may be presented in range format herein. It will be understood that such range formats are used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values ​​explicitly recited as the upper and lower limits of the range, but also all individual numerical values ​​or subranges contained within the range, as if each numerical value and subrange were explicitly recited. For example, a numerical range of about 1 to about 4.5 should be interpreted not only to include the explicitly recited lower limit of 1 to about 4.5, but also to include individual numbers such as 2, 3, 4, etc., subranges such as 1-3, 2-4, etc. The same principle applies to ranges recited with only one numerical value, such as "less than about 4.5," which should be interpreted as including all of the values ​​and ranges recited above. Furthermore, such interpretation should apply regardless of the breadth of the range or the characteristic being described.

[0121]

[0170] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosed subject matter belongs. Although representative methods, devices, and materials are described herein, any methods, devices, and materials similar or equivalent to those described herein can be used in the practice or testing of this disclosed subject matter.

[0122]

[0171] Following long-standing patent law convention, the terms "a" and "an" mean "one or more" when used in this application, including the claims.

[0123]

[0172] Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood in all instances to be governed by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and appended claims are approximations that may vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter.

[0124]

[0173] As used herein, the terms "about" and "substantially," when used in reference to a value or amount of mass, weight, time, volume, concentration, or percentage, are meant to encompass variations from the specified amount of, in some embodiments, ±20%, in some embodiments ±10%, in some embodiments ±5%, in some embodiments ±1%, in some embodiments ±0.5%, and in some embodiments ±0.1%, as appropriate for practicing the disclosed methods.

[0125]

[0174] As used herein, the terms "substantially perpendicular" and "substantially parallel" are meant to encompass variations within ±10° of the perpendicular and parallel directions, respectively, in some embodiments, within ±5° of the perpendicular and parallel directions, respectively, in some embodiments, within ±1° of the perpendicular and parallel directions, respectively, and in some embodiments, within ±0.5° of the perpendicular and parallel directions, respectively.

[0126]

[0175] As used herein, the term "and / or," when used in the context of a list of entities, refers to those entities either occurring alone or in combination. Thus, for example, the phrase "A, B, C, and / or D" includes A, B, C, and D individually, but also any and all combinations and subcombinations of A, B, C, and D.

[0127] References

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Claims

1. 1. A method for selectively recovering at least one of two or more metals from a material, comprising: (a) mixing a material containing two or more metals with an oxidizing agent to form a mixture; (b) subjecting the mixture to a flash joule heating process; and (c) separating and selectively recovering at least one or more first metals of the two or more metals of the material from at least one or more second metals of the two or more metals of the material. The above method, comprising:

2. 10. The method of claim 1, wherein the oxidizing agent is selected from the group consisting of a chlorine agent, a fluorine agent, a bromine agent, an iodine agent, and combinations thereof.

3. The method of claim 1 , wherein the oxidizing agent comprises a chlorine agent.

4. 4. The method of claim 3, wherein the chlorine agent is selected from the group consisting of halogen salts, ammonium chloride, and combinations thereof.

5. 4. The method of claim 3, wherein the chlorine agent is sodium chloride.

6. The chlorine agent is Cl ２ The method of claim 3, wherein

7. The method of any one of claims 3 to 6, wherein the flash joule heating process comprises an electrothermal chlorination process.

8. 8. The method of claim 7, wherein the flash joule heating process is carried out at a temperature of 630°C to 830°C.

9. The method of claim 8 , wherein the one or more first metals comprise In.

10. 8. The method of claim 7, wherein the flash heating process is carried out at a temperature greater than 1240°C.

11. (a) the one or more first metals comprise a metal selected from the group consisting of Sn and Mn; 11. The method of claim 10, wherein (b) the one or more second metals comprise a metal selected from the group consisting of Au and Cr.

12. subjecting the mixture to a flash joule heating process; (a) subjecting the mixture to a first flash joule heating process at a first temperature to form a first product; (b) subjecting the first product to a first evaporation process to form a first residue product; and (b) subjecting the first residue product to a second flash joule heating process at a second temperature. The method according to any one of claims 1 to 6, comprising:

13. The method of claim 12 , wherein the second temperature is greater than the first temperature.

14. (a) the first flash joule heating process comprises a first electrothermal chlorination process; 14. The method of claim 12 or 13, wherein (b) the second flash joule heating process comprises a second electrothermal chlorination process.

15. (a) the first flash joule heating process is carried out at a temperature of 630°C to 830°C; 15. The method of claim 14, wherein (b) the second flash joule heating process is carried out at a temperature greater than 1240°C.

16. The method of any one of claims 12 to 15, wherein the first evaporative process forms an evaporative phase.

17. The method of claim 16 , wherein the evaporable phase comprises an In-containing compound.

18. 18. The method of any one of claims 12 to 17, wherein the first residue product comprises a compound comprising a metal selected from the group consisting of Sn, Mn, Au, and Cr.

19. 20. The method of claim 18, wherein the second flash joule heating process forms a second product.

20. 20. The method of claim 19, wherein the second product is subjected to a second evaporation process to form a second residue product.

21. 21. The method of claim 20, wherein the second residue product comprises a compound comprising a metal selected from the group consisting of Au and Cr.

22. 22. The method of any one of claims 20 to 21, wherein the second evaporation process forms a second evaporative phase.

23. 23. The method of claim 22, wherein the second evaporable phase comprises a compound comprising a metal selected from the group consisting of Sn and Mn.

24. subjecting the mixture to a flash joule heating process; (a) forming a second residue product by said second flash joule heating process; (b) subjecting the second product to a second evaporation process to form a second residue product; and (c) subjecting the second residue product to a third flash joule heating process at a third temperature. The method according to any one of claims 12 to 23, comprising:

25. (a) the second temperature is greater than the first temperature; 25. The method of claim 24, wherein (b) the third temperature is greater than the second temperature.

26. The method of any one of claims 1 to 25, wherein the material is waste material.

27. 27. The method of claim 26, wherein the waste material is post-consumer electronic waste.

28. 27. The method of claim 26, wherein the waste is industrial waste.

29. 29. The method of claim 28, wherein the industrial waste material is selected from the group consisting of coal fly ash, bauxite residue, ore, mining tailings, and dredge mud.

30. 27. The method of claim 26, wherein the waste material comprises indium-tin oxide (ITO).

31. 27. The method of claim 26, wherein the waste material is electrode waste material.

32. The electrode waste is In ２ O ３ , SnO ２ , Au, MnO, Cr ２ O ３ 32. The method of claim 31 , comprising a compound selected from the group consisting of:

33. The method of any one of claims 1 to 6, wherein the mixture further comprises a reducing agent.

34. The reducing agent comprises a carbon source, a metal(0) source, H ２ 34. The method of claim 33, wherein the hydroxyl group is selected from the group consisting of:

35. 35. The method of claim 34, wherein the reducing agent comprises a metal(0) source.

36. 36. The method of claim 35, wherein the metal(0) source comprises a tin(0) source.

37. The reducing agent is H ２ 35. The method of claim 34, comprising:

38. The reducing agent is argon or nitrogen (N ２ ) in H ２ 38. The method of claim 37, comprising:

39. The reducing agent is argon or nitrogen (N ２ ) based on the volume of 1% to 5% H ２ 39. The method of claim 38, comprising:

40. 35. The method of claim 34, wherein the reducing agent comprises a carbon source.

41. 41. The method of claim 40, wherein the flash joule heating process comprises an electrothermal carbochlorination process.

42. (a) the flash joule heating process forms a first product; (b) performing a first evaporation process on the first product to form a first residue product; (c) the method further comprises mixing a reducing agent with the first residue product to form a second mixture; 7. The method of any one of claims 1 to 6, wherein the method further comprises: (d) subjecting the second mixture to a second Flash Joule heating process.

43. (a) performing a treatment on the first residue product prior to performing the second flash joule heating process; 43. The method of claim 42, wherein (b) the treatment is selected from the group consisting of an aqueous treatment, an aqueous acid treatment, and an aqueous base treatment.

44. 44. The method of claim 43, wherein said treating said first residue product increases the purity of one or more metals recovered from said first residue product.

45. The reducing agent comprises a carbon source, a metal(0) source, H ２ 45. The method of any one of claims 42 to 44, wherein the compound is selected from the group consisting of:

46. 46. ​​The method of claim 45, wherein the reducing agent comprises a metal(0) source.

47. 47. The method of claim 46, wherein the metal(0) source comprises a tin(0) source.

48. The reducing agent is H ２ 46. ​​The method of claim 45, comprising:

49. The reducing agent is argon or nitrogen (N ２ ) in H ２ 49. The method of claim 48, comprising:

50. The reducing agent is argon or nitrogen (N ２ ) based on the volume of 1% to 5% H ２ 50. The method of claim 49, comprising:

51. 46. ​​The method of claim 45, wherein the reducing agent comprises a carbon source.

52. (a) the flash joule heating process for the mixture comprises an electrothermal chlorination process; 52. The method of claim 51, wherein (b) the second flash joule heating process on the second mixture comprises an electrothermal carbochlorination process.

53. 53. The method of claim 52, wherein the first evaporative process forms a first evaporative phase.

54. 54. The method of claim 53, wherein the first evaporable phase comprises a compound comprising a metal selected from the group consisting of Fe, Ni, Mn, Cu, and combinations thereof.

55. 55. The method of any one of claims 52 to 54, wherein the first residue product comprises compounds comprising a metal selected from the group consisting of Si, Ta, and combinations thereof.

56. 56. The method of any one of claims 52 to 55, wherein the second flash joule heating process forms a second product.

57. 57. The method of claim 56, wherein the second product is subjected to a second evaporation process to form a second residue product.

58. 58. The method of claim 57, wherein the second residue product comprises a compound comprising Ta.

59. 59. The method of any one of claims 57 to 58, wherein the second evaporation process forms a second evaporative phase.

60. 60. The method of claim 59, wherein the second evaporable phase comprises a compound containing Si.

61. 61. The method of any one of claims 33 to 60, wherein the material is waste material.

62. 62. The method of claim 61, wherein the waste material is post-consumer electronic waste.

63. 62. The method of claim 61, wherein the waste is industrial waste.

64. 64. The method of claim 63, wherein the industrial waste material is selected from the group consisting of coal fly ash, bauxite residue, ore, mining tailings, and dredge mud.

65. 62. The method of claim 61, wherein the waste material comprises Ta.

66. 62. The method of claim 61, wherein the waste material is capacitor waste material.

67. The capacitor waste is Fe ２ O ３ , NiO, MnO, CuO, SiO ２ , Ta ２ O ５ 67. The method of claim 66, comprising a compound selected from the group consisting of:

68. 68. The method of any one of the preceding claims, wherein at least one of the two or more metals is selectively recovered from the material with a selectivity of at least 70 wt% purity of the at least one metal.

69. 69. The method of claim 68, wherein the selectivity is at least 90 wt%.

70. 69. The method of claim 68, wherein the selectivity is at least 95 wt%.

71. 69. The method of claim 68, wherein the selectivity is at least 97 wt%.

72. 69. The method of claim 68, wherein the selectivity is at least 99 wt%.

73. 69. The method of claim 68, wherein the selectivity is at least 99.999 wt%.

74. 1. A system for selectively recovering at least one metal of two or more metals, comprising: (a) a source of a mixture comprising two or more metal-containing materials and an oxidizing agent; (b) a cell operably connected to the source such that the mixture can flow into the cell and be held under compression; (c) an electrode operably connected to the pressure cell; and (d) a flash power supply for applying a voltage across the mixture to perform a flash Joule heating process on the mixture. Including, 74. The system is designed and operable to carry out the method of any one of claims 1 to 73, wherein at least one or more first metals of two or more metals in the material are separated and selectively recovered from at least one or more second metals of the two or more metals in the material.

75. 75. The system of claim 74, wherein the source of the mixture comprises the material, the oxidizing agent, and a reducing agent.

76. 75. The system of claim 74, comprising a second source comprising a reducing agent.

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