Method and system for recovering and reusing conductive additives for flash joule heating.

Abstract

Methods and systems for the recovery and reuse of conductive additives for flash Joule heating. Conductive additives or flash Joule heating used in materials such as electronic waste, ore, fly ash, soil, and / or bauxite residue can be recovered with a high recovery rate of over 85%, which can then be reused in further flash Joule heating processes. Conductive additives can be separated from the products of flash Joule heating processes by sieving or centrifugation, filtration, and drying.

Description

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[0001] Cross-reference of related applications This application claims the following priorities: (1) U.S. Patent Application No. 63 / 420,282, filed on October 28, 2022, entitled "Methods And Systems For The Recovery And Reuse Of Conductive Additives For Flash Joule Heating"; (2) PCT Patent Application No. PCT / US23 / 65506, filed on April 7, 2023, entitled "Heavy-Metal-Reduced Post-Industrial Waste In Cementitious Materials And Methods Of Making And Using Thereof"; and (3) U.S. Patent Application No. 63 / 589,489, filed on October 11, 2023, entitled "Methods For Remediation Of PFAS-Contaminated Soil By Rapid Electrothermal Mineralization".

[0002] The methods and systems of the present invention are also related to PCT Patent Applications Nos. PCT / US21 / 52030, PCT / US21 / 52043, PCT / US21 / 52057, and PCT / US21 / 52070, each filed on September 24, 2021, and each entitled "Ultrafast Flash Joule Heating Synthesis Methods And Systems For Performing Same".

[0003] Each of these patent applications is co-owned by the owner of the present invention and is hereby incorporated by reference in its entirety.

Technical Field

[0004] The present invention relates to methods and systems for the recovery and reuse of conductive additives for flash Joule heating.

[0005] Government interest This invention was made possible with the support of grant number FA9550-22-1-0526 awarded by the U.S. Air Force Office of Scientific Research and grant number W912HZ-21-2-0050 awarded by the U.S. Army Corps of Engineers Research and Development Center. The Government has certain rights to this invention. [Background technology]

[0006] Flash Joule heating (FJH) is characterized by its ultra-fast processing time and ultra-low energy consumption, making it an innovative method for the production of functional materials [Luong 2020; Chen I 2021; Deng I 2022; Stanford 2020] and sustainable waste management [Luong 2020; Algozeeb 2020; Barbhuiya 2021; Wyss 2021; Wyss 2022; Chen II 2021]. For example, applications of the FJH process have been reported for the recovery of precious metals from electronic waste (e-waste), the removal of heavy metals from e-waste, coal fly ash, and contaminated soil, and the recovery of rare earth elements from coal fly ash, bauxite residue, and e-waste [Deng 2021; Deng II 2022].

[0007] In FJH processes, when insulating inorganic or organic materials are used, conductive additives must be added and mixed with the inorganic materials to ensure good conductivity. Applicable conductive additives include many types of carbon and metals. Conductive additives typically constitute a large portion of the material cost in FJH processes. Therefore, the recovery and reuse of conductive additives is often desired to reduce material costs in FJH processes.

[0008] Chemical processes can be used to remove conductive additives. For example, in the synthesis of transition metal carbides by flash Joule heating, carbon additives were removed by a calcium etching protocol [Deng I 2022], and in the synthesis of corundum nanoparticles by pulsed DC heating processes, carbon additives were removed by calcination in air [Deng III 2022]. However, these processes are energy-intensive, and the carbon additives could not be recovered and reused.

[0009] Therefore, the need for recovery and reuse of conductive additives for flash joule heating remains. [Overview of the project]

[0010] The present invention relates to a method and system for recovering and reusing conductive additives for flash joule heating.

[0011] In a general embodiment, the present invention relates to a method comprising mixing a first material with a conductive additive to form a first mixture. The method further comprises performing a flash Joule heating process on the first mixture to form a product. The product contains the conductive additive obtained in the first mixture. The obtained conductive additive is selected from the group consisting of (i) a conductive additive, (ii) a different conductive additive, and (iii) a combination thereof. The method further comprises separating at least a portion of the obtained conductive additive from the product to obtain a recovered conductive additive. The method further comprises using the recovered conductive additive in a second flash Joule heating process. The recovered conductive material is mixed with a second material for use in the second flash Joule heating process. The second material is identical to or different from the first conductive material.

[0012] The implementation of the present invention may include one or more of the following features:

[0013] The resulting conductive additive may contain conductive additives.

[0014] The resulting conductive additive may contain different conductive additives.

[0015] The method may further include separating at least a portion of the second obtained conductive additive from the second product formed in the second flash-joule heating process to obtain a second recovered conductive additive. The method may further include using the second recovered conductive additive in a third flash-joule heating process. The second recovered conductive additive may be mixed with a third material for use in the third flash-joule heating process. The third material may be the same as or different from the first material and / or the second material.

[0016] The process of separating and reusing the recovered conductive additive can be repeated with respect to multiple additional flash Joule heating processes performed in series.

[0017] Additional conductive additives may be mixed with the recovered conductive additives and the second material before performing the second flash Joule heating process.

[0018] The first material may be prepared from electronic waste, ore, fly ash, soil, and / or bauxite residue.

[0019] The second material may be prepared from electronic waste, ore, fly ash, soil, and / or bauxite residue.

[0020] The first material could be soil.

[0021] The soil may be contaminated soil containing heavy metals, persistent organic pollutants, and pollutants selected from the group consisting of polyfluoroalkyl substances and perfluoroalkyl substances (PFAS).

[0022] The pollutant can be a heavy metal selected from the group consisting of lead (Pb), arsenic (As), zinc (Zn), cobalt (Co), cadmium (Cd), copper (Cu), mercury (Hg), and nickel (Ni).

[0023] The pollutant can be a persistent organic pollutant selected from the group consisting of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, organochlorine pesticides, total petroleum hydrocarbons, and PFAS.

[0024] The soil can be contaminated soil containing persistent and bioaccumulative pollutants.

[0025] The persistent and bioaccumulative pollutants can include one or more perfluoroalkyl substances and polyfluoroalkyl substances (PFAS).

[0026] The first material can be fly ash.

[0027] The conductive additive can be selected from the group consisting of elemental carbon, carbon black, graphene, flash graphene, coal, anthracite, coke, metallurgical coke, calcined coke, activated carbon, biochar, natural gas carbon with its hydrogen atoms removed, activated carbon, shungite, plastic waste, carbonaceous carbon derived from plastic waste, food waste, carbonaceous carbon derived from food waste, biomass, carbonaceous carbon derived from biomass, hydrocarbon gas products, metals, and mixtures thereof.

[0028] The conductive additive can be selected from the group consisting of metallurgical coke (metcoke), bituminous activated carbon (BAC), and combinations thereof.

[0029] The conductive additive can be biochar.

[0030] The conductive additive can be fiber and / or graphite.

[0031] The conductive additive can be carbon fiber.

[0032] The metal may be selected from the group consisting of metal particles, metal alloys, and metal carbides.

[0033] The metal may contain metal particles, including titanium.

[0034] The metal can be selected from the group consisting of metal nanoparticles, metal microparticles, metal milliparticles, and metal centi-particles.

[0035] The metal may contain metal carbides, including tungsten carbide.

[0036] The step of separating at least a portion of the obtained conductive additive from the product to obtain the recovered conductive additive may be a sieving process.

[0037] The step of separating at least a portion of the obtained conductive additive from the product to obtain the recovered conductive additive can be performed based on the particle size of the conductive additive and the particle size of the product.

[0038] The separation step may include sieving to separate at least a portion of the resulting conductive additive from the product.

[0039] The step of separating at least a portion of the obtained conductive additive from the product to obtain the recovered conductive additive may be based on the density difference between the conductive additive and the product. In many cases, carbon additives float in water. In many cases, metal additives sink in water.

[0040] The separation step may utilize a liquid to separate at least a portion of the resulting conductive additive from the product.

[0041] The liquid may be selected from the group consisting of water, salts dissolved in water, organic solvents, and ionic liquids.

[0042] The liquid could be water.

[0043] At least a portion of the resulting conductive additive may float on or near the upper surface of the liquid used for separation.

[0044] The conductive additive may be a conductive carbon additive.

[0045] The separation step may include decanting and / or skimming at least a portion of the resulting conductive additive from the product.

[0046] At least a portion of the conductive additive settles in the liquid used for separation.

[0047] Conductive additives contain metals.

[0048] The recovery rate of the conductive additive may be at least 85%. The recovery rate of the conductive additive is calculated by dividing the weight of the recovered conductive additive recovered from the product by the weight of the conductive additive in the first mixture.

[0049] The recovery rate could be at least 90%.

[0050] The recovery rate could be at least 92%.

[0051] The recovery rate could be at least 95%.

[0052] In a further general embodiment, the present invention relates to a system comprising a first source of a first mixture of a first material mixed with a conductive additive. The system further comprises a flash Joule heating system comprising (i) a cell operably connected to the first source such that the first mixture can be flowed into the cell and held under compression; (ii) an electrode operably connected to a pressure cell; and (iii) a flash power supply for applying a voltage over the entire mixture to perform a flash Joule heating process to form a product comprising the first mixture and the obtained conductive additive. The obtained conductive additive is selected from the group consisting of (i) a conductive additive, (ii) different conductive additives, and (iii) combinations thereof. The system further comprises a separator for separating a portion of the obtained conductive additive from the product to obtain a recovered conductive additive. The system further comprises a mixer for mixing the recovered conductive additive with a second material to form a second mixture. The second material is identical to or different from the first material. The system further includes a second source of the second mixture operably connected to the flash Joule heating system for use in the flash Joule heating system.

[0053] The implementation of the present invention may include one or more of the following features:

[0054] The resulting conductive additive may contain conductive additives.

[0055] The resulting conductive additive may contain different conductive additives.

[0056] This system may be capable of repeatedly separating and reusing recovered conductive additives in relation to multiple additional Joule heating processes performed in series.

[0057] The system may include a second source of additional conductive material. The additional source may be operably connected to the mixer so that the additional conductive material is mixed with the conductive additive and the second material recovered in the mixer to form a second mixture.

[0058] The first material may be prepared from electronic waste, ore, fly ash, soil, and / or bauxite residue.

[0059] The second material may be prepared from electronic waste, ore, fly ash, soil, and / or bauxite residue.

[0060] The first material could be soil.

[0061] The soil may be contaminated soil containing heavy metals, persistent organic pollutants, and pollutants selected from the group consisting of polyfluoroalkyl substances and perfluoroalkyl substances (PFAS).

[0062] The contaminants may be heavy metals selected from the group consisting of lead (Pb), arsenic (As), zinc (Zn), cobalt (Co), cadmium (Cd), copper (Cu), mercury (Hg), and nickel (Ni).

[0063] The pollutants may be persistent organic pollutants selected from the group consisting of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, organochlorine pesticides, total petroleum hydrocarbons, and PFAS.

[0064] The soil may be contaminated, containing persistent and bioaccumulative pollutants.

[0065] Persistent and bioaccumulative contaminants may include one or more perfluoroalkyl and polyfluoroalkyl substances (PFAS).

[0066] The first material could be fly ash.

[0067] The conductive additive may be selected from the group consisting of elemental carbon, carbon black, graphene, flash graphene, coal, anthracite, coke, metallurgical coke, calcined coke, activated carbon, biochar, natural gas carbon from which its hydrogen atoms have been removed, activated carbon, shungite, plastic waste, carbon derived from plastic waste, food waste, carbon derived from food waste, biomass, carbon derived from biomass, hydrocarbon gas products, metals, and mixtures thereof.

[0068] The conductive additive may be selected from the group consisting of metallurgical coke (methcoke), bituminous activated carbon (BAC), and combinations thereof.

[0069] The conductive additive can be biochar.

[0070] The conductive additive may be fibers and / or graphite.

[0071] The conductive additive can be carbon fiber.

[0072] The metal may be selected from the group consisting of metal particles, metal alloys, and metal carbides.

[0073] The metal may contain metal particles, including titanium.

[0074] The metal can be selected from the group consisting of metal nanoparticles, metal microparticles, metal milliparticles, and metal centi-particles.

[0075] The metal may contain metal carbides, including tungsten carbide.

[0076] The separator can be a sieve.

[0077] The separator may be operable to separate at least a portion of the resulting conductive additive from the product based on the particle size of the conductive additive and the particle size of the product, thereby obtaining the recovered conductive additive.

[0078] The separator may include a sieve for separating at least a portion of the conductive additive from the product based on the particle size of the conductive additive and the particle size of the product.

[0079] The separator may be operable to separate at least a portion of the resulting conductive additive from the product based on the density difference between the conductive additive and the product, thereby obtaining the recovered conductive additive.

[0080] This system may further contain a liquid. The separator may be able to operate using the liquid to separate at least a portion of the resulting conductive additive from the product.

[0081] The liquid may be selected from the group consisting of water, salts dissolved in water, organic solvents, and ionic liquids.

[0082] The liquid could be water.

[0083] The separator may be operable to suspend at least a portion of the resulting conductive carbon additive on or near the upper surface of the liquid within the separator.

[0084] The conductive additive may be a conductive carbon additive.

[0085] The separator may include a decanter and / or skimmer for decanting and / or skimming at least a portion of the resulting conductive additive from the product.

[0086] At least a portion of the resulting conductive additive may settle in the liquid used for separation.

[0087] Conductive materials may contain metals.

[0088] This system may have a conductive additive recovery rate of at least 85%. The conductive additive recovery rate is calculated by dividing the weight of the recovered conductive additive recovered from the product by the weight of the conductive additive in the first mixture.

[0089] The recovery rate could be at least 90%.

[0090] The recovery rate could be at least 92%.

[0091] The recovery rate could be at least 95%. [Brief explanation of the drawing]

[0092] [Figure 1] This figure shows the carbon residue after soil remediation using the flash Joule heating (FJH) process. Figure 1 is the TGA curve for the remediated soil with residual carbon. TGA was performed in air at a heating rate of 10°C·min⁻¹. [Figure 2] This shows the separation and reuse of metallurgical coke (methcoke) from soil improved by the FJH process. Figure 2A is a photograph of the soil / methcoke mixture before FJH. Figure 2B is a photograph of the soil / methcoke mixture after FJH. Figure 2C shows the separation of soil and methcoke by sieving. Figure 2D is a photograph of the separated soil and methcoke. Figure 2E is a photograph of the soil / methcoke mixture after FJH. (Most of the methcoke was recovered from the previous FJH trail.) Figure 2F is a photograph of the separated soil and methcoke. [Figure 3] The Raman spectra of metcoke are shown. Figure 3A shows the Raman spectrum of the metcoke raw materials. Figure 3B shows the Raman spectra of FJH and the separated metcoke. The Raman spectra showed that metcoke was converted to flash graphene after the FJH process. [Figure 4] This shows the measurement of soil carbon content. Figure 4A is the calibration curve for measuring soil carbon content. Figure 4B shows the soil carbon content in the raw soil and treated soil after removal of carbon additives by sieving. [Figure 5]This shows the separation and reuse of carbon additives and bituminous activated carbon (BAC). Figure 5A is a photograph of the soil and BAC mixture. Figure 5B is a photograph of the soil and BAC mixture after FJH. Figure 5C shows the separation of soil and BAC by sieving. Figure 5D is a photograph of the separated treated soil and recovered BAC. Figure 5E is a photograph of the soil and reused BAC mixture after FJH. Figure 5F is a photograph of the separated treated soil and recovered BAC. [Figure 6] This shows the recycling of biochar from treated soil. Figure 6A is a photograph of the initial biochar before the rapid electrothermal mineralization (REM) process. Figure 6B is a photograph of the soil / biocal mixture before REM. Figure 6C is a photograph of the soil / biocal mixture after REM. Figure 6D is a photograph of the REM soil mixed with a biochar dispersant after centrifugation. Figure 6E is a photograph of the recycled biochar after REM, dispersion, centrifugation, and drying. [Figure 7] A comparison of biochar and recycled biochar is shown. Figure 7A is the XRD pattern, and Figure 7B is the Raman spectrum. [Figure 8] These are the TGA results for soil. Figure 8A shows the raw soil (soil contaminated with PFAS). Figure 8B shows the REM-treated soil mixed with biochar. Figure 8C shows the REM-treated soil after biochar removal by centrifugation. The TGA test was performed in air at a heating rate of 10°C / min-1. [Figure 9] This shows the mineralization ratio of PFOA using biochar and recycled biochar as conductive additives after REM treatment. The REM process was performed once with an input voltage of 100V and a duration of 1 second. Error bars indicate the standard deviation, and N=3. [Figure 10] This shows the separation and recycling of conductive additives, methcoke, from soil. Figure 10A is a photograph of the soil / methcoke mixture before the REM process. Figure 10B is a photograph of the soil / methcoke mixture after the REM process. Figure 10C shows the separation of REM-treated soil and methcoke by sieving. [Figure 11]The Raman spectra of methocoke and recycled methocoke are shown. Figure 11A shows the initial methocoke before REM, and Figure 11B shows the recycled methocoke after REM. [Figure 12] This shows the mineralization ratio of p-fluorooctanoic acid (PFOA, a specific type of PFAS) using methcoke and recycled methcoke as conductive additives after REM treatment. The REM process was performed once with an input voltage of 100V and a duration of 1 second. Error bars indicate the standard deviation, and N=3. [Figure 13] This shows the separation and reuse of carbon additives. Figure 13A is a photograph of a mixture of coal fly ash (CFA) and metallurgical coke (methcoke). Figure 13B is a photograph of the mixture of CFA and methcoke after flash Joule heating (FJH). Figure 13C shows the separation of CFA and methcoke by sieving. Figure 13D is a photograph of the separated CFA and recovered methcoke. Figure 13E is a photograph of the mixture of CFA and recovered methcoke after FJH. Figure 13F is a photograph of the separated CFA and recovered methcoke. [Figure 14] The residual carbon in the CFA sample after sieving separation is shown (TGA curve of purified CFA after CB removal by sieving). TGA was performed in air at a heating rate of 10°C / min. [Figure 15] This is a flow diagram of an embodiment of the method of the present invention. [Figure 16] This is a schematic diagram of an embodiment of the system of the present invention. [Modes for carrying out the invention]

[0093] The present invention relates to a method and system for recovering and reusing conductive additives for flash joule heating.

[0094] In the FJH process, conductive additives may be added to and mixed with inorganic materials to ensure good conductivity, such as when insulating inorganic materials are used in the FJH process. Based on the difference in physical properties between the treated inorganic material (or other materials used in the FJH process) and the carbon conductive additive, it is possible to separate them and recover and reuse the conductive additive. Using relatively coarse-grained carbon as the conductive additive and separating the carbon additive from the inorganic material can be carried out by a simple and cost-effective sieving process. Various coarse-grained carbon additives can be used, including metallurgical coke (methcoke) and bituminous activated carbon (BAC). This process is applicable to many inorganic materials (or other materials) that have the characteristics of fine powders, as exemplified by coal fly ash (CFA) and contaminated soil.

[0095] Carbon residue after the FJH process After the FJH treatment process, a significant amount of residual carbon remains in the remaining solid. For example, in soil remediation with FJH, contaminated soil is mixed with a carbon additive in a 2:1 mass ratio. After the FJH purification process, the residual carbon has a mass of approximately 27% by weight, according to thermogravimetric analysis (TGA), as shown in Figure 1. During the FJH process, easily decomposable components in the soil were broken down. Therefore, in the TGA measurement, the majority of the weight loss was attributable to residual carbon.

[0096] Soil recovery and reuse Soil contaminated with heavy metals / persistent organic pollutants The FJH process can be used to remediate soil contaminated with heavy metals including lead (Pb), arsenic (As), zinc (Zn), cobalt (Co), cadmium (Cd), copper (Cu), mercury (Hg), and nickel (Ni), as well as persistent organic pollutants (POPs) such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, organochlorine pesticides, total petroleum hydrocarbons, and PFAS. The FJH process for remediating such multiple pollutants in contaminated soil may also be referred to as the high-temperature electric heating (HET) process.

[0097] Residual carbon from soil after the FJH process (HET process) can be separated by sieving based on the particle size difference between the soil and the introduced carbon. Using methocoke as an example, separation of treated soil from residual methocoke was achieved, with a carbon recovery rate of approximately 92%. Figures 2A-2D.

[0098] Metcoke has a larger particle size than soil. Figure 2A. After the FJH process, the particle size of methcoke remained larger than that of soil. Figure 2B. Therefore, soil and methcoke were separated by sieving. Figures 2C-2D. For example, a mixture of soil and methcoke with masses of m(soil) = 334 mg and m(methcoke) = 166 mg. After FJH, the remaining mass of soil and methcoke was m(soil + methcoke, FJH) = 445 mg. After sieving separation, purified soil with a mass of m(purified soil) = 293 mg and recovered methcoke with a mass of m(recovered methcoke) = 152 mg were obtained. As a result, a recovery rate of approximately 92% of methcoke was obtained. The mass loss of approximately 8% was thought to be due to consumption during the FJH process.

[0099] The recycled metcoke was converted to flash graphene (Figures 3A-3B), which has superior conductivity and can be reused in the FJH process (Figures 2E-2F), significantly reducing material consumption. For example, the recovered metcoke (152 mg) and some fresh metcoke (14 mg) were then used as conductive additives in the FJH process. Figure 2E. After similar sieving separation, metcoke with a mass of m(recovered metcoke) = 155 mg was recovered (Figure 2F), resulting in a metcoke recovery rate of approximately 93%. This demonstrates that simple sieving recycling can significantly reduce the consumption of conductive additives.

[0100] After the separation of the carbon conductive additive, the soil carbon content in the raw and treated soils was measured. Figures 4A-4B show that the carbon content in the treated soil was approximately 3.5%, comparable to that of the raw soil (approximately 3.7%). The residual carbon additive can compensate for the reduction of organic carbon during the FJH process, resulting in similar total carbon content in both the treated and raw soils.

[0101] Other inexpensive carbon additives, such as bituminous activated carbon (BAC), can also be used for separation. Figures 5A-5F show that a mixture of soil (approximately 200 mg) and BAC (approximately 100 mg) was used in the FJH process. Figure 5A shows that after the FJH purification and sieving process (Figures 5B-5C), the recovered mass of BAC was m(recovered BAC) = 95.5 mg (Figure 5D), resulting in a BAC recovery rate of approximately 95.5%.

[0102] The recovered BAC can be reused for further FJH treatment. To demonstrate this, another batch of soil (200 mg) was purified using recovered BAC (95.5 mg) with some fresh BAC (4.5 mg) as a conductive additive. Figure 5E. After the FJH process and subsequent sieving separation, BAC was recovered with a mass of m(recovered BAC) = 93.2 mg (Figure 5F), resulting in a BAC recovery rate of approximately 93.2%.

[0103] Soil contaminated with PFAS The FJH process can be used to remediate soil contaminated with persistent and bioaccumulative contaminants, such as soil contaminated with perfluoroalkyl and polyfluoroalkyl substances (PFAS). The FJH process for remediating such soil contaminated with persistent and bioaccumulative contaminants, such as soil contaminated with perfluoroalkyl and polyfluoroalkyl substances (PFAS) ("PFAS-contaminated soil"), may also be referred to as the rapid electrothermal mineralization (REM) process.

[0104] In this process, PFAS-contaminated soil is mixed with conductive additives such as biochar to ensure proper electrical conductivity. After the FJH process (REM process), the used carbon additives can be separated from the soil mixture and then reused for the next batch of soil improvement. For example, perfluorooctanoic acid (PFOA) is a specific type of PFAS. PFOA-contaminated soil and biochar with m(soil) = 400 mg and m(biocchar) = 200 mg. Figures 6A-6B. After the REM process, the remaining mass of the mixture was m(mixture, REM) = 476 mg. Figure 6C. After centrifugation, filtration, and drying (Figure 6D shows where the biochar 601 floated and the soil 602 settled), purified REM-treated soil with m(purified soil) = 307 mg and recycled biochar with m(recycled biochar) = 169 mg were obtained. Figure 6E.

[0105] The biochar was flash-heated to improve its conductivity and then used as a conductive additive. Figures 7A and 7B show a comparison of biochar and recycled biochar using their XRD patterns (lines 701 and 702, respectively) (Figure 7A) and Raman spectra (lines 701 and 702, respectively) (Figure 7B). No significant compositional differences were observed between them, demonstrating the effectiveness of the biochar recycling process. In this case, the biochar was pre-flashed before use, converted to graphene, and then used as a conductive additive.

[0106] According to the TGA results, the weight loss of the raw soil is due to the decomposition of organic compounds, which account for approximately 7% by weight. Figure 8A. After mixing with biochar and treating with REM, the soil weight loss increased to approximately 18% by weight, which is due to the oxidation of carbon in the biochar. Figure 8B. After removing the biochar by centrifugation and drying, the weight loss of the REM soil decreased to a low value of approximately 5% by weight, demonstrating that the majority of the biochar in the soil was successfully removed. Figure 8C.

[0107] Biochar was separated from the soil by dispersion and centrifugation at a recycling rate of approximately 85% by weight (Figures 6A-6E, 7A-7B, and 8A-8C), and reused in a second REM treatment with comparable PFAS mineralization performance (Figure 9). Figure 9 shows that when biochar and recycled biochar were used as conductive additives, there was almost no change in the PFOA mineralization rate (approximately 94%), demonstrating the effectiveness of reusing recycled biochar in the REM process.

[0108] Similarly, when metcoke is used as a conductive additive, approximately 91% by weight can be recycled after REM by simple sieving (Figures 10A-10C and 11A-11B) and then reused with similar performance (Figure 12). For example, soil contaminated with PFOA and metcoke were mixed with m(soil) = 400 mg and m(metcoke) = 200 mg. Figure 10A. After the REM process, the remaining mass of the mixture was m(mixture, REM) = 473 mg. Figure 10B. After sieving separation, purified REM-treated soil with m(purified soil) = 287 mg and recycled metcoke with m(recycled metcoke) = 186 mg were obtained. Figure 10C. The recycling yield of metcoke was calculated to be approximately 93% by weight. The Raman spectra in Figures 11A-11B show that the initial metcoke was converted to crystalline flash graphene during the REM process. When recycled metcoke is used as a conductive additive, the PFOA mineralization ratio can reach a comparable value of approximately 91%, demonstrating the effectiveness of reusing recycled metcoke in the REM process. Figure 12. This significantly reduces material consumption in the REM process while requiring greater processing.

[0109] CFA recovery and reuse Based on the particle size and density differences between coal fly ash (CFA) and carbon, residual carbon from CFA can also be separated using physical processes. Using methocoke as an example, the separation of purified CFA and methocoke by sieving is demonstrated. CFA has a fine particle size, while methocoke, with its relatively larger size, was used for the analysis. A mixture of CFA (approximately 333 mg) and methocoke (approximately 167 mg) was used. Figure 13A. After FJH, the particle sizes of CFA and methocoke remained almost unchanged. Figure 13B. Thus, the separation of CFA and methocoke by sieving was performed. Figure 13C. In a typical process, the recovered mass of methocoke was m(recovered methocoke) = 154 mg, which represents a recovery rate of approximately 92% of methocoke. Figure 13D.

[0110] The recovered metcoke could be reused as a conductive additive for further purification of CFA, reducing the cost of FJH purification. As shown in Figure 13E, recovered metcoke (154 mg) with several new metcoke (13 mg) as a conductive additive for the purification of CFA (333 mg). After separation by the FJH process and subsequent sieving, metcoke with a mass of m(recovered metcoke) = 156 mg was recovered, and the metcoke recovery rate was approximately 93%. Figure 13F.

[0111] After the sieving separation process, the residual carbon content in the treated CFA (plot 1401) was reduced to approximately 3%. See Figure 14 (dashed line 1402 for 100% by weight). The residual carbon can be completely removed by calcination in air. The selection of an appropriate carbon removal method may depend on the landfill or application of the purified CFA.

[0112] Furthermore, other inexpensive carbon additives such as bituminous activated carbon (BAC) can also be used for separation. Figures 10A-10F. Similar to metcoke, BAC with a relatively large size was used for analysis. A mixture of CFA (approximately 200 mg) and BAC (approximately 100 mg) was used. Figure 10A. After FJH, the particle sizes of CFA and BAC remained unchanged. Figure 10B. Thus, separation of CFA and BAC was performed by sieving. Figure 10C. In a typical process, the recovered mass of BAC was m(recovered BAC) = 95 mg, which represents a recovery rate of approximately 95% of BAC. Figure 10D.

[0113] The recovered BAC can be reused for further FJH treatment. To demonstrate this, CFA (200 mg) was purified by adding several fresh BAC (5.5 mg) as a conductive additive to recovered BAC (154 mg). Figure 10E. After the FJH process and subsequent sieving separation, BAC was recovered with a mass of m(recovered BAC) = 94 mg, and the BAC recovery rate was approximately 94%. Figure 10F.

[0114] Separation process Table I below summarizes the recovery and reuse of conductive additives in the previously discussed and described examples. [Table 1]

[0115] Except for the soil and biochar examples, the separation processes used were based on sieving to separate the conductive carbon additive from the resulting product of the FJH process. The percentage yield of such sieving provided a recovery rate of at least 90%, at least 92% in some embodiments, and at least 95% in further embodiments. The separation processes in the soil and biochar examples utilized centrifugation and drying, resulting in a recovery rate of at least 85%.

[0116] Further and additional separation processes may be used to separate the conductive additive from the resulting product of the FJH process. For example, the separation may be based on the particle size of the conductive additive and the particle size of the resulting product of the FJH process. This may be sieving or other processes that separate materials based on their size. Furthermore, for example, the separation may be based on the density difference between the conductive additive and the resulting product of the FJH process. This may involve using a liquid (such as water) to separate the conductive additive from the resulting product of the FJH process. This may further include the conductive additive floating on or near the upper surface of the liquid used for separation, while the resulting product of the FJH process sinks in the liquid (or vice versa). This may further include decanting and / or skimming of the conductive additive (or the resulting product of the FJH process).

[0117] Further applications and benefits Figure 15 is a flow diagram of an embodiment of the method of the present invention. In step 1501, the method mixes a first material with a conductive additive to form a first mixture. In step 1502, the method performs a flash Joule heating process on the first mixture to form a product. The product contains at least a portion of the conductive additive in the first mixture. In step 1503, the method separates at least a portion of the conductive additive from the product to obtain a recovered conductive additive. In step 1504, the method uses the recovered conductive additive in a second flash Joule heating process. The conductive material is mixed with a second material for use in the second flash Joule heating process. The second material is either identical to or different from the first material.

[0118] Figure 16 is a schematic diagram of an embodiment of the system of the present invention. The system includes a source 1601 for a first mixture of a first material mixed with a conductive additive. The system further includes a flash Joule heating system 1602. Such a flash Joule heating system may include (i) a cell operably connected to the first source so that the first mixture can be introduced into the cell and held under compression; (ii) electrodes operably connected to a pressure cell; and (iii) a flash power supply for applying a voltage over the entire mixture to perform a flash Joule heating process to form a product containing at least a portion of the conductive additive of the first mixture. The system further includes a separator 1803 for separating a portion of the conductive additive from the product to obtain a recovered conductive additive. The system further includes a mixer 1604 for mixing the recovered conductive additive with a second material to form a second mixture. The second material may be identical to or different from the first material. The system further includes a second source 1605 of the second mixture operably connected to the flash Joule heating system 1602 for the use of the second mixture in the flash Joule system. It should be noted that the flash Joule heating system 1602 may have multiple reactors for flash Joule heating to occur, and as a result, the system may perform flash Joule heating of the first mixture from source 1601 in the same or different reactors while the system performs flash Joule heating of the second mixture from source 1602. Furthermore, the source of the first mixture 1801 may be the same as the source of the second mixture 1605.

[0119] These methods and systems for recovering and reusing conductive additives for FJH can be used in countless FJH processes, including precious metal recovery from electronic waste, heavy metal removal from electronic waste and coal fly ash, removal of heavy metals and organic pollutants from contaminated soil for soil remediation, and rare earth element recovery from coal fly ash, bauxite residue, and electronic waste. This separation and recovery of conductive additives from processed materials can be utilized to reduce material costs in FJH processes. Conductive additives can be separated and recovered by simple, energy-efficient processes such as sieving.

[0120] In addition to waste reduction and resource recovery, FJH has been used to synthesize a variety of functional nanomaterials, including transition metal carbide nanocrystals, silicon carbide, corundum nanoparticles, molybdenum disulfide, and boron nitride. The recovery and reuse of conductive additives can also be used for the separation and purification of these materials.

[0121] Conventional processes for separating residual carbon additives using FJH-treated inorganic materials typically involve chemical processes such as calcium etching or calcination. Separation processes such as sieving have the following advantages: (1) Sieving is a physical process, so energy consumption is very low, whereas chemical processes involve high-temperature processing with high energy consumption; (2) Carbon additives can be recovered and reused with a high yield of over 95%, whereas chemical processes typically etch the carbon and therefore cannot be reused. Furthermore, sieving processes for recovering and reusing conductive additives are feasible on a large scale.

[0122] 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 invention. The embodiments and examples provided herein are merely illustrative and not intended to limit the invention. Many variations and modifications of the invention disclosed herein are possible and within the scope of the invention. The scope of protection is not limited by the preceding statements but only by the following claims, which include all equivalents of the subject matter of the claims.

[0123] All patents, patent applications, and publication disclosures cited herein are incorporated herein by reference in their entirety, insofar as they provide illustrative, procedural, or other detailed information that complements what is described herein.

[0124] Quantitative and other numerical data may be presented in range form as herein. It should be understood that such range forms are used merely for convenience and brevity, and should be interpreted flexibly to include not only the explicitly listed numbers as limits to the range, but also all individual numbers or subranges contained within that range, as if each number and subrange were explicitly enumerated. For example, a numerical range of approximately 1 to approximately 4.5 should be interpreted to include not only the explicitly enumerated limits of 1 to approximately 4.5, but also individual numbers such as 2, 3, 4, and subranges such as 1 to 3, 2 to 4, etc. The same principle applies to ranges enumerating only one number, such as "less than approximately 4.5," which should be interpreted to include all the previously enumerated values ​​and ranges. Furthermore, such interpretation should apply regardless of the width of the range or the characteristics described.

[0125] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art in the field to which the subject matter of this disclosure pertains. Any methods, devices, and materials similar to or equivalent to those described herein may be used in the practice or testing of the subject matter disclosed herein, and representative methods, devices, and materials are described herein.

[0126] In accordance with established patent law conventions, the terms “a” and “an,” when used in this application, including in the claims, mean “one or more.”

[0127] Unless otherwise indicated, all numbers used herein and in the claims to represent quantities of components, reaction conditions, etc., should be understood in all examples to be modified by the term “approximately.” Therefore, unless otherwise indicated, the numerical parameters described herein and in the appended claims are approximations that may vary depending on the desired properties to be obtained by the subject matter of this disclosure.

[0128] As used herein, the terms “about” and “substantially” mean, when referring to a value, or quantity of mass, weight, time, volume, concentration, or percentage, to include variations from a particular quantity of ±20%, ±10%, ±5%, ±1%, ±0.5%, and ±0.1% in some embodiments, such variations are appropriate for carrying out the disclosed method.

[0129] As used herein, the terms “substantially perpendicular” and “substantially parallel” mean, in some embodiments, variations within ±10° of the perpendicular and parallel directions, in some embodiments, within ±5° of the perpendicular and parallel directions, in some embodiments, within ±1° of the perpendicular and parallel directions, and in some embodiments, within ±0.5° of the perpendicular and parallel directions.

[0130] As used herein, the term "and / or," when used in the context of a list of entities, means that the entities exist individually 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 of A, B, C, and D, as well as subcombinations.

[0131] References PCT International Patent Publication No.WO 2022 / 067111,entitled “Ultrafast Flash Joule Heating Methods And System For Performing Same,” toJ.M.Tour,et al.,filed September 24,2021(the “Tour ’111 PCT Application”). Algozeeb,W.A.,et al.,“Flash graphene from plastic waste,” ACS Nano,2020,14,15595-15604(“Algozeeb 2020”). Barbhuiya,N.H.,et al.,“The Future of flash graphene for the sustainable management of solid waste,” ACS Nano,2021,15,15461-15470(“Barbhuiya 2021”). Chen,W.,et al.,“Millisecond conversion of metastable 2D materials by flash Joule heating,” ACS Nano,2021,15,1282-1290(“Chen I 2021”). Chen,W.,et al.,“Ultrafast and controllable phase evolution by flash Joule heating,” ACS Nano,2021,15,11158-11167(Chen II 2021”). Deng,B.,et al.,“Phase controlled synthesis of transition metal carbide nanocrystals by ultrafast flash Joule heating,” Nat.Commun.,2022,13,262(“Deng I 2022”). Deng,B.,et al.,“Rare earth elements from waste,” Sci.Adv.,2022,8,eabm3132(“Deng II 2022”). Deng,B.,et al.,“High-surface-area corundum nanoparticles by resistive hotspot-induced phase transformation,” Nat Commun,2022,13,5027(Deng III 2022). Deng,B.,et al.,“Urban mining by flash Joule heating,” Nat.Commun.,2021,12,5794(“Deng 2021”). Luong,D.X.,et al.,“Gram-scale bottom-up flash graphene synthesis,” Nature,2020,577,647-651(“Luong 2020”). Stanford,M.G.,et al.,“Flash Graphene Morphologies,” ACS Nano,2020,14,13691-13699(“Stanford 2020”). Wyss,K.M.et al.,“Upcycling end-of-life vehicle waste plastic into flash graphene,” Communications Engineering,2022,1,3(“Wyss 2022”). Wyss,K.M.,et al.,“Converting plastic waste pyrolysis ash into flash graphene,” Carbon,2021,174,430-438(“Wyss 2021”).

Claims

1. It is a method, (a) Mixing the first material with a conductive additive to form the first mixture, (b) Performing a flash Joule heating process on the first mixture to form a product, wherein the product comprises a conductive additive obtained in the first mixture, and the obtained conductive additive is (i) The conductive additive, (ii) Different conductive additives, and (iii) To be selected from the group consisting of these combinations, (c) Separating at least a portion of the obtained conductive additive from the product to obtain the recovered conductive additive, (d) Using the recovered conductive additive in a second flash Joule heating process, (i) The recovered conductive material is mixed with a second material for use in the second flash Joule heating process, (ii) A method comprising using the second material which is the same as or different from the first material.

2. The method according to claim 1, wherein the conductive additive obtained comprises the conductive additive.

3. The method according to claim 1, wherein the conductive additive obtained comprises the different conductive additives.

4. The method described above is (a) Separating at least a portion of the second conductive additive obtained from the second product formed in the second flash Joule heating process to obtain the second recovered conductive additive, (b) Using the second recovered conductive additive in a third flash Joule heating process, (i) The second recovered conductive additive is mixed with a third material for use in the third flash Joule heating process, (ii) The method according to claim 1, further comprising using the third material which is the same as or different from the first material and / or the second material.

5. The method according to claim 4, wherein the step of separating and reusing the recovered conductive additive according to claim 4 is repeated with respect to a plurality of additional flash Joule heating processes performed in series.

6. The method according to claim 1, wherein the additional conductive additive is mixed with the recovered conductive additive and the second material before the second flash-joule heating process is performed.

7. The method according to claim 1, wherein the first material is prepared from electronic waste, ore, fly ash, soil, and / or bauxite residue.

8. The method according to claim 7, wherein the second material is prepared from electronic waste, ore, fly ash, soil, and / or bauxite residue.

9. The method according to claim 1, wherein the first material is soil.

10. The method according to claim 9, wherein the soil is contaminated soil containing heavy metals, persistent organic pollutants, and pollutants selected from the group consisting of polyfluoroalkyl substances and perfluoroalkyl substances (PFAS).

11. The method according to claim 10, wherein the pollutant is a heavy metal selected from the group consisting of lead (Pb), arsenic (As), zinc (Zn), cobalt (Co), cadmium (Cd), copper (Cu), mercury (Hg), and nickel (Ni).

12. The method according to claim 10, wherein the pollutant is a persistent organic pollutant selected from the group consisting of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, organochlorine pesticides, total petroleum hydrocarbons, and PFAS.

13. The method according to claim 9, wherein the soil is contaminated soil containing persistent and bioaccumulative pollutants.

14. The method according to claim 13, wherein the persistent and bioaccumulative contaminant comprises one or more perfluoroalkyl substances and polyfluoroalkyl substances (PFAS).

15. The method according to claim 1, wherein the first material is fly ash.

16. The method according to claim 1, wherein the conductive additive is selected from the group consisting of elemental carbon, carbon black, graphene, flash graphene, coal, anthracite, coke, metallurgical coke, calcined coke, activated carbon, biochar, natural gas carbon from which hydrogen atoms have been removed, activated carbon, shungite, plastic waste, carbon derived from plastic waste, food waste, carbon derived from food waste, biomass, carbon derived from biomass, hydrocarbon gas products, metals, and mixtures thereof.

17. The method according to claim 16, wherein the conductive additive is selected from the group consisting of metallurgical coke (methocoke), bituminous activated carbon (BAC), and combinations thereof.

18. The method according to claim 16, wherein the conductive additive is biochar.

19. The method according to claim 16, wherein the conductive additive is a fiber and / or graphite.

20. The method according to claim 19, wherein the conductive additive is carbon fiber.

21. The method according to claim 16, wherein the metal is selected from the group consisting of metal particles, metal alloys, and metal carbides.

22. The method according to claim 21, wherein the metal comprises metal particles containing titanium.

23. The method according to claim 21, wherein the metal is selected from the group consisting of metal nanoparticles, metal microparticles, metal milliparticles, and metal centi-particles.

24. The method according to claim 21, wherein the metal comprises a metal carbide containing tungsten carbide.

25. The method according to claim 1, wherein the step of separating at least a portion of the obtained conductive additive from the product to obtain the recovered conductive additive is a sieving process.

26. The method according to claim 1, wherein the step of separating at least a portion of the conductive additive obtained from the product to obtain the recovered conductive additive is based on the particle size of the conductive additive and the particle size of the product.

27. The method according to claim 26, wherein the separation step includes sieving to separate at least a portion of the obtained conductive additive from the product.

28. The method according to claim 1, wherein the step of separating at least a portion of the obtained conductive additive from the product to obtain the recovered conductive additive is based on the density difference between the conductive additive and the product.

29. The method according to claim 28, wherein the separation step includes using a liquid to separate at least a portion of the obtained conductive additive from the product.

30. The method according to claim 29, wherein the liquid is selected from the group consisting of water, salts dissolved in water, organic solvents, and ionic liquids.

31. The method according to claim 29, wherein the liquid is water.

32. The method according to any one of claims 29 to 31, wherein at least a portion of the obtained conductive additive floats on or near the upper surface of the liquid used for separation.

33. The method according to claim 32, wherein the conductive additive is a conductive carbon additive.

34. The method according to any one of claims 29 to 33, wherein the separation step includes decanting and / or skimming at least a portion of the obtained conductive additive from the product.

35. The method according to any one of claims 29 to 31, wherein at least a portion of the obtained conductive additive settles in the liquid used for separation.

36. The method according to claim 35, wherein the conductive additive includes a metal.

37. The method according to claim 1, wherein the recovery rate of the conductive additive is at least 85%, and the recovery rate of the conductive additive is obtained by dividing the weight of the recovered conductive additive recovered from the product by the weight of the conductive additive in the first mixture.

38. The method according to claim 37, wherein the recovery rate is at least 90%.

39. The method according to claim 37, wherein the recovery rate is at least 92%.

40. The method according to claim 37, wherein the recovery rate is at least 95%.

41. It is a system, (a) A first source of a first mixture of a first material mixed with a conductive additive, (b) A flash Joule heating system, (i) The cell is operably connected to the first supply source so that the first mixture can be flowed into the cell and held under compression, (ii) Electrodes operably connected to the pressure cell, (iii) A flash power supply for applying a voltage over the entire mixture to perform a flash Joule heating process to form a product comprising the first mixture, wherein the obtained conductive additive is (A) The conductive additive, (B) Different conductive additives, and (C) A flash joule heating system including a flash power supply selected from the group consisting of these combinations, (c) A separator for separating a portion of the conductive additive obtained from the product to obtain the recovered conductive additive, (d) A mixer for mixing the recovered conductive additive with a second material to form a second mixture, wherein the second material is the same as or different from the first material, (e) A system comprising a second source of the second mixture operably connected to the flash Joule heating system for use of the second mixture in the flash Joule heating system.

42. The system according to claim 41, wherein the conductive additive obtained comprises the conductive additive.

43. The system according to claim 41, wherein the obtained conductive additive includes the different conductive additives.

44. The system according to claim 41, wherein the system is operable to repeatedly separate and reuse the recovered conductive additive with respect to a plurality of additional Joule heating processes performed in series.

45. (a) The system comprises a second source of additional conductive material, (b) The system according to claim 41, wherein the additional supply source is operably connected to the mixer so that the additional conductive material is mixed in the mixer with the recovered conductive additive and the second material to form the second mixture.

46. The system according to claim 41, wherein the first material is prepared from electronic waste, ore, fly ash, soil, and / or bauxite residue.

47. The system according to claim 46, wherein the second material is prepared from electronic waste, ore, fly ash, soil, and / or bauxite residue.

48. The system according to claim 41, wherein the first material is soil.

49. The system according to claim 48, wherein the soil is contaminated soil containing heavy metals, persistent organic pollutants, and pollutants selected from the group consisting of polyfluoroalkyl substances and perfluoroalkyl substances (PFAS).

50. The system according to claim 49, wherein the pollutant is a heavy metal selected from the group consisting of lead (Pb), arsenic (As), zinc (Zn), cobalt (Co), cadmium (Cd), copper (Cu), mercury (Hg), and nickel (Ni).

51. The system according to claim 49, wherein the pollutant is a persistent organic pollutant selected from the group consisting of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, organochlorine pesticides, total petroleum hydrocarbons, and PFAS.

52. The system according to claim 48, wherein the soil is contaminated soil containing persistent and bioaccumulative pollutants.

53. The system according to claim 52, wherein the persistent and bioaccumulative contaminant comprises one or more perfluoroalkyl substances and polyfluoroalkyl substances (PFAS).

54. The system according to claim 41, wherein the first material is fly ash.

55. The system according to claim 41, wherein the conductive additive is selected from the group consisting of elemental carbon, carbon black, graphene, flash graphene, coal, anthracite, coke, metallurgical coke, calcined coke, activated carbon, biocarbon, natural gas carbon from which hydrogen atoms have been removed, activated carbon, shungite, plastic waste, carbon dioxide derived from plastic waste, food waste, carbon dioxide derived from food waste, biomass, carbon dioxide derived from biomass, hydrocarbon gas products, metals, and mixtures thereof.

56. The system according to claim 55, wherein the conductive additive is selected from the group consisting of metallurgical coke (methocoke), bituminous activated carbon (BAC), and combinations thereof.

57. The method according to claim 55, wherein the conductive additive is biochar.

58. The system according to claim 59, wherein the conductive additive is a fiber and / or graphite.

59. The system according to claim 58, wherein the conductive additive is carbon fiber.

60. The system according to claim 55, wherein the metal is selected from the group consisting of metal particles, metal alloys, and metal carbides.

61. The system according to claim 60, wherein the metal comprises metal particles containing titanium.

62. The system according to claim 60, wherein the metal is selected from the group consisting of metal nanoparticles, metal microparticles, metal milliparticles, and metal centi-particles.

63. The method according to claim 60, wherein the metal comprises a metal carbide containing tungsten carbide.

64. The system according to claim 41, wherein the separator is a sieve.

65. The system according to claim 41, wherein the separator is operable to separate at least a portion of the obtained conductive additive from the product based on the particle size of the conductive additive and the particle size of the product, thereby obtaining the recovered conductive additive.

66. The system according to claim 65, wherein the separator includes a sieve for separating at least a portion of the obtained conductive additive from the product based on the particle size of the conductive additive and the particle size of the product.

67. The system according to claim 41, wherein the separator is operable to separate at least a portion of the obtained conductive additive from the product based on the density difference between the conductive additive and the product to obtain a recovered conductive additive.

68. The system according to claim 67, wherein the system further comprises a liquid, and the separator is operable to use the liquid to separate at least a portion of the obtained conductive additive from the product.

69. The system according to claim 68, wherein the liquid is selected from the group consisting of water, salts dissolved in water, organic solvents, and ionic liquids.

70. The system according to claim 68, wherein the liquid is water.

71. The system according to any one of claims 68 to 70, wherein the separator is operable to suspend at least a portion of the obtained conductive carbon additive on or near the upper surface of the liquid in the separator.

72. The system according to claim 71, wherein the conductive additive is a conductive carbon additive.

73. The system according to any one of claims 68 to 72, wherein the separator includes a decanter and / or skimmer for decanting and / or skimming at least a portion of the obtained conductive additive from the product.

74. The system according to any one of claims 68 to 70, wherein at least a portion of the obtained conductive additive settles in the liquid used for separation.

75. The system according to claim 74, wherein the conductive additive includes a metal.

76. The system according to claim 41, wherein the system has a recovery rate of the conductive additive of at least 85%, and the recovery rate of the conductive additive is obtained by dividing the weight of the recovered conductive additive recovered from the product by the weight of the conductive additive in the first mixture.

77. The system according to claim 76, wherein the recovery rate is at least 90%.

78. The system according to claim 76, wherein the recovery rate is at least 92%.

79. The system according to claim 76, wherein the recovery rate is at least 95%.

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