Method and apparatus for producing rare earth elements from coal and clay ore

Abstract

A method for separating rare earth elements from coal and clay ore is disclosed. This method includes the steps of liquefying raw coal to form pitch or pitch resin, and filtering the pitch or pitch resin to capture rare earth elements. It also includes the step of purifying the pitch or pitch resin to produce mesophase pitch. Furthermore, it includes the step of subjecting the mesophase pitch or pitch resin to a low-crystallinity spinning process to form carbon fibers.

Description

[Technical Field]

[0001] cross reference This application claims priority to U.S. Provisional Patent Application No. 63 / 504,414, filed on 25 May 2023, entitled “RARE EARTH ELEMENTS FROM COAL AND CLAY ORES,” the disclosures of which are incorporated herein by reference in their entirety.

[0002] The embodiments described herein generally relate to carbon-based processing methods, and more specifically, to systems and methods for processing hydrocarbon-containing coal to produce advanced carbon materials and for extracting rare earth elements from coal deposits. [Background technology]

[0003] Coal has been mined for thousands of years and used for a variety of purposes. Since the Industrial Revolution, the primary use of coal has been to generate heat and energy to power homes, industries, and transportation. Initially, coal was widely used as fuel for rail transport during the Industrial Revolution, but with the advent of the automobile and the discovery of large oil deposits in the early 20th century, liquid petroleum-based fuels gained dominance in transportation.

[0004] However, research on coal continued, and its basic chemistry was well understood by at least the beginning of the 20th century. Although much research has been done on coal for over a century, the vast majority of this extensive prior research has been overwhelmingly focused on the development of fuels for transportation. The use of coal to produce other, more industrially relevant materials has not yet been sufficiently explored. For example, coal and its pre-processing products contain rare earth elements (REEs), including 17 elements such as dysprosium, neodymium, europium, terbium, and thulium.

[0005] REE is essential for the manufacture of high-demand products such as batteries and solar cells. It is also primarily used as a magnet, battery, and catalyst, and its need continues to grow in a wide range of cutting-edge applications, including defense technology, renewable energy technology, and commercial products. [Overview of the project] [Means for solving the problem]

[0006] A method for separating rare earth elements from coal and clay ore is provided. This method includes the steps of liquefying raw coal to form pitch or pitch resin, and filtering the pitch or pitch resin to capture the rare earth elements. In one example, the method further includes purifying the pitch or pitch resin to produce mesophase pitch, and subjecting the mesophase pitch or pitch resin to a low-crystallinity spinning process to form carbon fibers. In another example, the rare earth elements can be defined as including at least one of gallium, germanium, cerium, lanthanum, neodymium, praseodymium, scandium, yttrium, dysprosium, terbium, samarium, ytterbium, europium, promethium, gadolinium, holmium, lutetium, thulium, and erbium. In one example, the pitch or pitch resin may include isotropic pitch.

[0007] In at least one example, the step of filtering the pitch or pitch resin may include removing impurities and water and physically separating and detecting the rare earth elements. In one example, the method may further include a step of rehydrating the pitch or pitch resin to a moisture content of about 6% to about 8%. In some examples, the method may further include a step of separating the rare earth elements into heavy rare earth elements or light rare earth elements.

[0008] In some examples, a method for separating rare earth elements from coal and clay ores includes the step of modifying carbon fibers to bind or electrostatically interact with rare earth elements. In one example, the step of modifying carbon fibers to bind or electrostatically interact with rare earth elements includes attaching a mineral-binding protein or a lanthanide-binding protein to the carbon fibers. In another example, the step of modifying carbon fibers to bind or electrostatically interact with rare earth elements may include increasing the negative charge of the carbon fibers to increase the electrostatic interaction with rare earth elements.

[0009] In at least one example, a method for extracting rare earth elements from a coal deposit using a thermally swing adsorption system is provided. The method includes the steps of liquefying a coal deposit containing coal and clay ores to form a pitch, and feeding the pitch into a chamber of a thermally swing adsorption device. In one example, the method further includes the steps of adsorbing rare earth elements by a carbon monolith in the chamber, and discharging the pitch from the chamber of the thermally swing adsorption device.

[0010] In one example, a method for extracting rare earth elements using a thermally swing adsorption system may include the step of applying an electric current to a carbon monolith in a chamber to raise the temperature of the carbon monolith and desorb rare earth elements from the carbon monolith. In some examples, the step of adsorbing rare earth elements by a carbon monolith in the chamber may include moving the carbon monolith in the pitch. In one example, the carbon monolith may include coal-based activated carbon fibers. In one example, the liquefaction process may include crushing the coal deposit and suspending the coal solids in a fluid with a moisture content of about 6% to about 8%. In some examples, the crushed coal deposit may have a particle size of about 0.5 μm to about 50 μm.

[0011] In at least one example, a system for extracting rare earth elements from a coal deposit is provided. The system includes a first chamber including at least one carbon monolith and a second chamber including at least one carbon monolith. In one example, a thermally swing adsorption apparatus is configured to receive a feed of coal-based pitch including at least one rare earth element, and each carbon monolith of the thermally swing adsorption apparatus includes coal-based activated carbon fibers configured to capture rare earth elements.

[0012] In one example, at least one carbon monolith of the first chamber captures rare earth elements, and at least one carbon monolith of the second chamber desorbs rare earth elements while the carbon monolith of the first chamber releases rare earth elements. In one example, the first chamber and the second chamber operate periodically to perform continuous capture and release of rare earth elements, and while capture is being performed in one of the first chamber and the second chamber, release is being performed in the other of the first chamber and the second chamber. In some examples, each carbon monolith is functionalized to adsorb a specific rare earth element. In some examples, the coal-based activated carbon fibers are melt-blown from isotropic pitch.

Brief Description of the Drawings

[0013] The accompanying drawings, which show various embodiments of the apparatus, form a part of this specification. The illustrated embodiments are merely examples of the apparatus and do not limit its scope.

[0014] [Figure 1] A process flow for extracting rare earth elements from coal and clay ore to form carbon fibers according to one embodiment is shown.

[0015] [Figure 2] A system for separating rare earth elements from coal and clay ore according to one embodiment is shown.

[0016] [Figure 3]A schematic diagram of an electrothermal swing adsorption system equipped with multiple electrothermal swing adsorption devices, according to one embodiment of this disclosure, is shown.

[0017] [Figure 4A] A schematic diagram of an electric thermal swing adsorption device in a first configuration state according to one embodiment of the present disclosure is shown.

[0018] [Figure 4B] Figure 4A shows a schematic diagram of the second configuration state of the electric thermal swing adsorption device.

[0019] [Figure 5] This is a flowchart illustrating a method for extracting rare earth elements from coal deposits using an electrothermal swing adsorption system.

[0020] Throughout the drawing, the same reference number indicates similar elements, but not necessarily identical elements. [Modes for carrying out the invention]

[0021] As described below, advanced carbon materials such as rare earth elements and carbon fibers can be produced from mined, untreated coal. The descriptions herein are illustrative and do not limit the scope, applicability, or configuration described in the claims. Accordingly, without departing from the spirit and scope of this disclosure, modifications can be made to the function and arrangement of the described elements, and other steps or components can be omitted, replaced, or added as appropriate. For example, the described methods can be carried out in an order different from the order described, and each step can be added, deleted, or combined. Also, features described in relation to some embodiments can be combined with other embodiments.

[0022] Rare earth elements, such as neodymium, praseodymium, and scandium, are used in a wide range of applications. In this disclosure, rare earth elements may include scandium and yttrium in addition to the 15 lanthanides in the periodic table, and may also refer to gallium and germanium. Rare earth elements (REEs) are components of many products across a wide range of applications, including mobile phones, computer hard drives, electric and hybrid vehicles, and high-tech consumer goods such as flat-screen monitors and televisions. Defense applications include electronic displays, guidance systems, lasers, radar, and sonar systems. The amount of REE used in a product may not represent a large proportion of the product's total weight, value, or volume, but REEs can be critical to the product's function.

[0023] The average rare earth element (REE) content in coal is approximately 68 ppm, while that in coal ash is approximately 404 ppm. REE can be recovered and purified from coal. Direct coal liquefaction (DCL) is a process in which REE is extracted by directly contacting coal with a catalyst in the presence of a solvent, adding hydrogen (H2) under high temperature and pressure conditions, and then filtering or processing to form a raw material liquefaction that can be further refined into products such as liquid fuels. This process is called "direct" because it does not include a pretreatment step in which the coal is gasified to form synthesis gas (which can then be converted into liquid products). The latter two-step approach, namely the route that converts coal to liquid via synthesis gas, is called indirect coal liquefaction (ICL). Therefore, in principle, the DCL process is simpler and more efficient than the other two. However, DCL may use an external H2 supply source, which may need to be supplied by gasifying additional coal, biomass, and / or heavy residues produced in the DCL reactor. The DCL process yields a relatively broad range of hydrocarbon products, predominantly aromatic, encompassing various molecular weights and forms. Therefore, significant upgrades may be required to obtain the desired product.

[0024] The DCL process may include a step of adding hydrogen to coal through hydrogenation, which breaks down the coal's organic structure into soluble products. The reaction in DCL is carried out under high temperature and high pressure conditions, such as 750°F–850°F (approximately 399°C–454°C) and 1,000–2,500 psia, in the presence of a solvent. The solvent is used to facilitate the extraction of coal and the addition of hydrogen. The solubilized products, mainly containing aromatic compounds, can then be upgraded using conventional petroleum refining techniques, such as hydrogenation, to meet the specifications of the final liquid product.

[0025] The following description details representative embodiments shown in the attached drawings. However, the following description is not intended to limit the embodiments to any particular preferred form. Rather, it is intended to include alternatives, modifications, and equivalents that may fall within the spirit and scope of the embodiments described, as defined by the attached claims.

[0026] The systems and methods described herein may include the steps of liquefying coal to form coal tar pitch and removing rare earth elements (REE) from the pitch. The coal tar pitch may be heat-treated to a liquid crystal phase exhibiting anisotropic spheres of mesophase and further spun to form carbon fibers. In some examples, the pitch may be supplied to an electrothermal swing adsorption device in which the REE can be adsorbed by a carbon monolith.

[0027] According to some embodiments, as shown in Figure 1, a method 100 for separating rare earth elements from coal and clay ore may include: a step 102 of liquefying raw coal to form pitch or pitch resin; a step 104 of filtering the pitch or pitch resin to capture rare earth elements; a step 106 of separating the rare earth elements into heavy or light rare earth elements; a step 108 of purifying the pitch or pitch resin to produce mesophase pitch; a step 110 of subjecting the mesophase pitch or pitch resin to a low-crystallinity spinning step to form carbon fibers; and a step 112 of modifying the carbon fibers to bond or electrostatically interact with rare earth elements. In some examples, the filtration step can increase the concentration of rare earth elements (REE) in the pitch from about 400 ppm to about 8000 ppm.

[0028] In some embodiments, step 102, which involves liquefying raw coal to form pitch or pitch resin, may include bringing a certain amount of coal into direct contact with a catalyst, applying a predetermined pressure of about 1000 pounds / square inch absolute pressure (psia) or less to the coal and solvent in the presence of a solvent, heating the coal and solvent to a predetermined temperature of about 380°C or less, and liquefying at least a portion of the coal to form coal tar pitch. In some examples, the coal may include anthracite and / or coal mined from the Powder River Basin in Wyoming. The catalyst may include any catalyst described herein or catalysts known in the industry, and the solvent may also include any solvent described herein or solvents known in the industry. In some examples, the solvent may include one or more of N-methyl-2-pyrrolidone (NMP), quinoline, Fluorinert FC-71, silicone oil, phthalates such as dioctyl phthalate, Siltherm 800, and other suitable solvents or carriers. In some examples, the catalyst may be, but is not limited to, a Lewis acid catalyst.

[0029] In many cases, step 102 involves bringing the catalyst and coal into direct contact in the presence of a solvent and added hydrogen, while heating the coal to a predetermined pressure (e.g., approximately 975 psia or less, approximately 950 psia or less, approximately 925 psia or less, approximately 900 psia or less, approximately 875 psia or less, approximately 850 psia or less, approximately 825 psia or less, approximately 800 psia or less, approximately 775 psia or less, approximately 750 psia or less, approximately 725 psia or less, approximately 700 psia or less, approximately 6 Below 75 psia, below approximately 650 psia, below approximately 625 psia, below approximately 600 psia, below approximately 575 psia, below approximately 550 psia, below approximately 525 psia, below approximately 500 psia, below approximately 475 psia, below approximately 450 psia, below approximately 425 psia, below approximately 400 psia, below approximately 375 psia, below approximately 350 psia, approximately 350 psia to approximately 450 psia, approximately 400 psia to approximately 500 psia, approximately 450 psia This involves pressurizing the coal to approximately 550 psia, 500 psia to 600 psia, 550 psia to 650 psia, 600 psia to 700 psia, 650 psia to 750 psia, 700 psia to 800 psia, 750 psia to 850 psia, 800 psia to 900 psia, and 850 psia to 950 psia), while simultaneously pressurizing the coal to a predetermined temperature (for example, below approximately 380°C). This may include heating to approximately 375°C or below, approximately 370°C or below, approximately 365°C or below, approximately 360°C or below, approximately 355°C or below, approximately 350°C or below, approximately 325°C or below, approximately 320°C or below, approximately 315°C or below, approximately 310°C or below, approximately 305°C or below, approximately 300°C or below, approximately 295°C or below, approximately 290°C or below, approximately 285°C or below, approximately 280°C or below, approximately 275°C or below, approximately 270°C or below, approximately 265°C or below, approximately 260°C or below, approximately 255°C or below, and approximately 250°C or below. As mentioned above, raw coal may contain rare earth elements (REE). In some cases, coal and / or clay ore may contain approximately 400 ppm of REE.

[0030] Step 104 of method 100 for separating rare earth elements from coal and clay ore includes filtering pitch or pitch resin to capture the rare earth elements. In some embodiments, the filter may include a carbon fiber filter, but other types of filters may also be used. In some examples, the filter may include a nylon filter, a woven fabric filter, a membrane system, a mechanical collector, a wet scrubber, or an electrostatic precipitator. In some examples, the filter can provide a filtrate quality of less than 0.3 to 0.5 ppm for particles with a particle size of about 0.5 to 1 μm. In some examples, the filter may be less than 100 μm. In other embodiments, the filter may be less than 80 μm. For example, rare earth elements (REEs) may have particle sizes of approximately 5 μm or less, approximately 10 μm or less, approximately 20 μm or less, approximately 30 μm or less, approximately 50 μm or less, approximately 60 μm or less, approximately 70 μm or less, or they may be in the range of approximately 5 to approximately 15 μm, approximately 10 to approximately 20 μm, approximately 15 to approximately 25 μm, approximately 20 to approximately 30 μm, approximately 25 to approximately 35 μm, approximately 30 to approximately 40 μm, approximately 35 to approximately 45 μm, approximately 40 to approximately 50 μm, approximately 45 to approximately 60 μm, approximately 50 to approximately 70 μm, approximately 60 to approximately 80 μm, approximately 70 to approximately 90 μm, or approximately 80 to approximately 100 μm.

[0031] In some cases, pitch or pitch resin may contain isotropic pitch. Since isotropic pitch is amorphous and the resulting carbon fibers have low strength, anisotropic pitch is primarily used when producing high-strength, high-elasticity carbon fibers. The physical properties and composition of isotropic pitch are important in producing high-strength, high-elasticity carbon fibers. In particular, high-strength carbon fibers can be produced by melting isotropic pitch to obtain carbon fibers with specific ranges and levels of molecular weight, softening point, and viscosity.

[0032] In some examples, method 100 may include a step 106 for sorting rare earth elements. Rare earth elements with atomic numbers 57–63 are considered light rare earth elements (LREE), and rare earth elements with atomic numbers 64–71 are considered heavy rare earth elements (HREE). Because the separation and purification of rare earth elements are difficult, their production costs are very high. Since the outermost electron configurations of rare earth elements are filled in a similar manner, these elements exhibit similar reactivity. This similarity makes it difficult to separate them from one another. In some examples, step 106 may include solvent extraction. Solvent extraction involves mixing various acids having different affinities for different rare earth elements and allowing these mixtures to stand, thereby gradually increasing the concentration of a particular rare earth metal at each separation step. In some examples, a purity of over 99.9% can be obtained by solvent extraction. In some examples, rare earth elements can be separated using ligands. In other examples, ion exchange or precipitation methods can be used to recover rare earth elements from the pregnant leach solution obtained by acid leaching.

[0033] In some examples, method 100 may include step 108 of purifying pitch or pitch resin to produce mesophase pitch. In some examples, this method includes heat treatment of coal tar pitch to invert it into a liquid crystal phase exhibiting anisotropic spheres of mesophase pitch. Mesophase pitch has a heterogeneous structure including anisotropic regions. Various spinning modes, such as centrifugal spinning, jet spinning, and conventional melt spinning, have been used to spin mesophase pitch. Mesophase pitch is a precursor for medium- and high-performance carbon fibers, highly conductive carbon foams, and other advanced carbon materials. Large, highly aromatic molecules stack to form liquid crystal domains, which can be oriented by different processing methods to produce highly oriented crystalline materials with high strength, high elasticity, and excellent electrical and thermal conductivity. In some examples, step 108 includes hydrogenation, which can produce mesophase pitch. In other examples, mesophase pitch can be prepared using sulfur as a crosslinking agent. The action of the crosslinking agent depends to some extent on the degree of swelling of SBS (i.e., antimony sulfur). Crosslinking reactions can form a crosslinked polymer network within the mesophase pitch.

[0034] In some examples, method 100 may include step 110 of subjecting mesophase pitch or pitch resin to a low-crystallinity spinning process to form carbon fibers. The post-treatment conditions and structure of the mesophase pitch determine the performance and structure of the resulting carbon material containing carbon fibers. In addition to low density, high modulus of elasticity, and high strength, carbon fibers have resistance to deformation and high temperatures, a low coefficient of thermal expansion, excellent mechanical properties, and even thermal and electrical conductivity. Carbon fiber materials can be used as both structural and functional materials. High-performance carbon fibers have high specific modulus of elasticity and specific strength. While the density of high-quality carbon fibers is only about 25% of that of steel wire, their tensile strength can reach three times that of steel wire, and their tensile modulus of elasticity can reach five times that of steel wire, making them the best material among high-performance fiber materials.

[0035] After the desired mesophase pitch is prepared, it is spun into fibers by conventional techniques such as melt spinning, centrifugal spinning, blow spinning, or any other known method. As mentioned above, in order to obtain highly oriented carbonaceous fibers that can be obtained with high Young's modulus and high tensile strength, the pitch must form a homogeneous bulk mesophase with large aggregate domains under static conditions and must not exhibit thixotropy under the conditions used for spinning.

[0036] The spinning temperature of the pitch naturally depends on the temperature at which the pitch exhibits an appropriate viscosity. A pitch with a mesophase content of about 40% by weight exhibits a viscosity of about 200 poise at about 300°C and about 10 poise at about 375°C, while a pitch with a mesophase content of about 90% by weight exhibits a similar viscosity at temperatures above 430°C. Within this viscosity range, fibers can be spun from the pitch. Preferably, the pitch has a mesophase content of about 50% to about 65% by weight and exhibits a viscosity of about 30% to about 150 poise at temperatures of about 340°C to about 380°C. Under such viscosity and temperature conditions, uniform fibers with a diameter of about 5 μm to about 25 μm can be spun.

[0037] In some examples, method 100 may include step 112 of modifying a carbon fiber filter to bind to or electrostatically interact with rare earth elements. For example, the step of modifying a carbon fiber filter to bind to or electrostatically interact with rare earth elements may include attaching mineral-binding proteins or lanthanide-binding proteins to the carbon fibers. For example, methylotropic bacteria can utilize lanthanides for binding to rare earth elements. Lanmodulin (LanM) has three binding sites and forms a complex that is highly stable and water-soluble across the entire rare earth element (REE) series while maintaining selectivity for non-rare earth elements. LanM enables the quantitative extraction and purification of REE from pre-combustion coal containing coal and pitch feedstock in a single step. In some examples, by utilizing the similarity of affinities between REEs, multiple types of REE and total REE can be recovered against non-REE elements. In some examples, other proteins such as Tf, Scn, and CaM also exhibit affinity for REE and can be used for REE separation.

[0038] In some examples, step 112, which modifies carbon fibers to bond or electrostatically interact with rare earth elements, may include increasing the negative charge of the carbon fibers to enhance electrostatic interaction with the rare earth elements. In some examples, carbon fibers can be functionalized to impart magnetic or electric field-related properties, such as by introducing magnetite (Fe3O4) to impart magnetic properties or by introducing chitosan to increase the maximum adsorption capacity of the material. In some examples, such functionalization can be achieved by preparing nanostructured silica-coated magnetite and then coating it with the desired functional group. The material thus obtained tends to have a high adsorption capacity for rare earth elements (REE) and exhibits magnetic properties, facilitating material separation processes in aqueous media.

[0039] Figure 2 is a flowchart of a system 200 for separating rare earth elements from coal and clay ore according to one embodiment. In some examples, system 200 may include a mine or source 202 from which coal and clay ore are extracted. Coal and its by-products (including coal ash from power generation, waste rock from coal sorting plants, acid mine wastewater treatment sludge, and young lignite found in areas such as Wyoming) may contain extractable high concentrations of rare earth elements. Some types of coal show relatively high rare earth concentrations at the hundreds of ppm level. Other coal deposits may have lower rare earth concentrations, reaching several thousand ppm. Since combustion has the effect of concentrating rare earth elements in ash by about 6 to 10 times compared to coal, coal ash can also be another source in system 200.

[0040] The coal for the supply source 202 is size-adjusted to facilitate processing in the crusher 204. In some examples, the ore crusher pulverizes the raw ore into ore particles. In some examples, the system 200 may include an ore crusher that pulverizes the raw ore to form ore particles with a diameter of approximately 1 mm to approximately 1 cm. In some examples, these particles may be further pulverized to a diameter of less than 1 mm. In other examples, the particles may have diameters of less than 1 μm, less than 10 μm, less than 50 μm, less than 200 μm, or less than 600 μm. In some examples, the pulverized particles may have particle sizes ranging from approximately 1 μm to approximately 1 mm. Other ranges include approximately 1 μm to 10 μm, approximately 10 μm to 50 μm, approximately 50 μm to 250 μm, approximately 250 μm to 500 μm, approximately 500 μm to 1 mm, approximately 1 mm to 200 mm, approximately 200 mm to 500 mm, or approximately 500 mm to 1 cm.

[0041] In some cases, after particle size adjustment, water can be removed from the coal or clay ore by a dewatering system 206. Dewatering methods include both mechanical dewatering and geotube dewatering. In mechanical dewatering, high-moisture crushed ore is sent to a mechanical dewatering unit 206 (e.g., a centrifuge, belt press, or filter press) for dewatering, and the filtered coal (filter cake) is further processed to remove impurities.

[0042] Geotube dehydration is a method of dehydration using geotubes. Geotubes are large filter bags made of geotextile. Crushed ore or clay is placed in the geotubes and the water is drained, leaving the solid material inside. Once the geotubes are filled with ore or clay, drainage is performed for a certain period of time. As drainage progresses and the geotubes contract, more ore or clay can be added to the geotubes. By repeating the filling and draining process, the geotubes are eventually filled. If necessary, the ore or clay can be further dehydrated by evaporation for several weeks. The dehydrated ore is then further processed to remove impurities.

[0043] System 200 further includes a detection and impurity removal system 208. In some examples, ore filtration may include physically separating and detecting rare earth elements by removing impurities and water. Crystallization can be used as a purification technique when the amount of impurities is very small or when the impurities have a significantly different solubility profile from the target compound. Impurities can be easily removed if they are more or less soluble than rare earth elements (REEs) in dehydrated ore or clay. In some examples, coal can also be beneficiated.

[0044] The ore dressing process may include heating the coal ore to one or more desired temperatures. These desired temperatures are in the range of approximately 100°C to 500°C, for example, approximately 100°C to 290°C, approximately 100°C to 150°C, approximately 125°C to 200°C, or approximately 150°C to 290°C. The temperature at which the ore is heated can be selected to selectively remove at least some, or at least one, type of impurities present in the ore. For example, the ore can be heated to approximately 100°C to 150°C to remove moisture from the coal, and heated to approximately 150°C to 290°C to remove volatile metals from the raw coal. In some cases, the ore dressing process may include heating the ore to a first desired temperature. Heating the ore to the first desired temperature can remove one or more first impurities. In some embodiments, the process may then include heating the ore to a second, higher desired temperature. By heating the ore to a second desired temperature, one or more second impurities can be removed.

[0045] The ore dressing process may include a step of heating the ore to a desired temperature for a desired time. The desired time can range from about 1 second to several days, for example, from about 1 second to about 1 minute, about 30 seconds to about 30 minutes, about 1 minute to about 1 hour, about 30 minutes to about 3 hours, about 1 hour to about 5 hours, about 3 hours to about 10 hours, about 7 hours to about 18 hours, about 12 hours to about 1 day, or about 18 hours to about 3 days. Generally, increasing the time the ore is heated to the desired temperature tends to increase the amount of one or more impurities removed from the ore. However, the ore has a maximum duration, and heating beyond this may have little or no effect on the amount of one or more impurities removed. In some cases, the ore dressing process may include a step of heating the ore to a first desired temperature for a first time, and then heating the ore to a second, higher desired temperature for a second time. The first and second times may be the same or different.

[0046] In some cases, as a further treatment after impurity removal and / or coal beneficiation, the beneficiated coal can be subjected to liquid extraction, such as pyrolysis (high-temperature pyrolysis or low-temperature pyrolysis). Other liquefaction treatments, such as direct or indirect liquefaction, membrane treatment, arc discharge treatment, supercritical solvent extraction, or electromagnetic heating, can be used instead of or in combination with pyrolysis. Liquid extraction can convert the beneficiated coal into pitch.

[0047] After the impurity removal system 208, the pitch can be rehydrated by the water replenishment system 210. Coal ore pitch can be rehydrated to a moisture content of 6% to 8% to prevent spontaneous combustion. After the impurity removal system 208, the ore can be sorted by the ore sorting system 212. The ore sorting system 212 includes physical sorting using a sensor detection system and can be configured to separate heavy rare earth element ore 214 and light rare earth element ore 216, as well as other metals / elements 218 that can be separated at this stage.

[0048] As described above, heavy rare earth elements 214 and light rare earth elements 216 can be separated by a sorting system 212 including solvent extraction. Solvent extraction involves mixing various acids having different affinities for different rare earth elements and allowing these mixtures to stand, thereby gradually increasing the concentration of a specific rare earth metal at each separation stage. In some cases, purity exceeding 99.9% can be achieved by solvent extraction. In some cases, ligands can be used to separate REE. In other cases, ion exchange and precipitation methods can be used to recover REE from the leached noble liquid obtained by acid leaching. However, other methods can also be used for the extraction of REE.

[0049] In some cases, rare earth elements can be extracted from coal deposits using an electrothermal swing adsorption system. Figure 3 shows a schematic diagram of an electrothermal swing adsorption system 300 comprising a plurality of electrothermal swing adsorption devices according to one embodiment of the present disclosure.

[0050] Figure 3 shows an electrothermal swing adsorption system 300 for capturing rare earth elements (REEs) from pitch according to one embodiment of the present disclosure. The electrothermal swing adsorption system 300 includes a pitch input stream 302 containing a high concentration of REEs and a filtered pitch output stream 304, which has a low concentration of REEs removed from the pitch during the swing adsorption process of the electrothermal swing adsorption system 300. Here, the term “filtered” does not necessarily mean that the REEs have been completely removed, but rather that the concentration of REEs in the pitch has been reduced. The pitch input stream 302 may contain any type of REE, including at least one of gallium, germanium, cerium, lanthanum, neodymium, praseodymium, scandium, yttrium, dysprosium, terbium, samarium, ytterbium, europium, promethium, gadolinium, holmium, lutetium, thulium, and erbium.

[0051] The electrothermal swing adsorption system 300 may include a plurality of electrothermal swing adsorption devices 310, 320, 330 arranged in series. In the illustrated embodiment, a first electrothermal swing adsorption device 310, a second electrothermal swing adsorption device 320, and a third electrothermal swing adsorption device 330 are shown. In other words, the pitch input flow 302 is filtered by the first electrothermal swing adsorption device 310, then filtered again by the second electrothermal swing adsorption device 320, and further filtered again by the third electrothermal swing adsorption device 330. However, the disclosure is not limited thereto, and the electrothermal swing adsorption system 300 may include more or fewer than three electrothermal swing adsorption devices to purify the pitch input flow 302.

[0052] In some embodiments, the electrothermal swing adsorption devices 310, 320, and 330 of the electrothermal swing adsorption system 300 can be arranged in parallel. In other words, the electrothermal swing adsorption devices 310, 320, and 330 can simultaneously filter the pitch input flow 302, thereby increasing the rate at which rare earth elements are removed from the pitch input flow 302.

[0053] Each of the electrothermal swing adsorption devices 310, 320, and 330 may be configured to capture specific rare earth elements (REEs). For example, the first electrothermal swing adsorption device 310 may be configured to remove gallium from the pitch input flow 302, and after gallium has been removed by the first electrothermal swing adsorption device 310, the second electrothermal swing adsorption device 320 may be configured to remove germanium from the pitch input flow 302, and after gallium and germanium have been removed by the first and second electrothermal swing adsorption devices 310 and 320, the third electrothermal swing adsorption device 330 may be configured to remove lanthanum from the pitch input flow 302. As a result, the pitch output flow 304 will be REE-free. The electrothermal swing adsorption system 300 may include additional electrothermal swing adsorption devices to remove other specific REEs from the pitch input flow 302. For example, after predetermined REE has been removed by the first electric thermal swing adsorption device 310, the second electric thermal swing adsorption device 320, and the third electric thermal swing adsorption device 330, a fourth electric thermal swing adsorption device can be provided and functioned to remove another REE from the pitch input flow 302.

[0054] In some examples, the electrothermal swing adsorption devices 310, 320, and 330 may include activated carbon monoliths for adsorbing rare earth elements (REE), as will be discussed later. The first REE-enriched pitch stream 311 can transfer or output the pitch inlet stream 302 to a first temporary storage container for storing the enriched REE pitch. The second enriched pitch stream 321 can transfer or output the pitch inlet stream 302 to a second temporary storage container for storing the enriched REE pitch. The third enriched pitch stream 331 can transfer or output the pitch inlet stream 302 to a third temporary storage container for storing the enriched REE pitch. In some examples, the first, second, and third temporary storage containers are different temporary storage containers, each storing a specific REE. In some embodiments, the first, second, and third temporary storage containers are the same temporary storage container, storing all the different REEs obtained from the pitch.

[0055] Figure 4A shows a schematic diagram of the electrothermal swing adsorption device 410 in a first configuration. The first electrothermal swing adsorption device 410 includes a first chamber 412 and a second chamber 413. The first chamber 412 and the second chamber 413 each contain at least one carbon monolith. In some embodiments, the first chamber 412 and the second chamber 413 each contain only a single carbon monolith. In some embodiments, the first chamber 412 and the second chamber 413 may each contain multiple carbon monoliths.

[0056] In the illustrated embodiment, the first chamber 412 contains an activated carbon monolith for adsorbing rare earth elements (REE), and the second chamber 413 contains a regenerating carbon monolith for desorbing the captured REE. The regenerating carbon monolith in the second chamber 413 has previously adsorbed REE. In some embodiments, the carbon monolith may not have adsorbed REE when it is first placed in the second chamber 413. The first chamber 412 and the second chamber 413 operate periodically to continuously adsorb and desorb REE.

[0057] The carbon monoliths in the first chamber 412 and the second chamber 413 each contain coal-based activated carbon fibers. Because coal-based activated carbon fibers are obtained from coal raw materials, they are 50% to 75% more economical than existing fibers produced from polyacrylonitrile (PAN), rayon, and petroleum pitch precursors. The carbon fibers can be produced by melt-blowing isotropic pitch obtained from sub-bituminous coal ore through a direct coal liquefaction process.

[0058] Carbon monoliths and coal-based activated carbon fibers may be functionalized to adsorb specific rare earth elements (REEs). The properties of the activated carbon fibers can be adjusted to achieve selective adsorption. The properties of the activated carbon fibers include pore diameter, pore size distribution, Brunauer-Emmett-Teller (BET) specific surface area, thermal conductivity, magnetism, bulk density, permeability, electrical resistance, and the like. In some examples, functionalization may include binding proteins or releasing them in response to a change in charge. In some examples, the carbon monoliths in the first chamber 412 and the carbon monoliths in the second chamber 413 may be similar and each may be configured to target the same specific REE.

[0059] For example, the bulk density of the carbon monolith may be greater than about 0.05 g / cm 3 It may also be. In some examples, the bulk density of the carbon monolith is about 0.05 g / cm 3 ~ about 0.7 g / cm 3 It may be within the range of. In some examples, the areal weight range of the fiber may include a bulk density of less than about 0.7 g / cm 3 In other examples, the bulk density may be less than 0.6 g / cm 3 less than 0.5 g / cm 3 less than, or less than 0.1 g / cm 3 It may also be. In some examples, the bulk density of the carbon monolith is from about 0.05 g / cm 3 ~ about 0.2 g / cm 3 It may be in the range of. As other ranges, about 0.2 g / cm 3 ~ about 0.4 g / cm 3 , about 0.4 g / cm 3 ~ about 0.5 g / cm 3 , about 0.5 g / cm 3 ~ about 0.6 g / cm 3 , or about 0.6 g / cm 3 ~ about 0.7 g / cm 3 can be mentioned. In some examples, the bulk density can be adjusted by adjusting the rate of temperature increase during the formation of the carbon fiber monolith, but the bulk density can also be adjusted by adjusting the airflow or oxygen concentration during the formation of the carbon fiber monolith.

[0060] In some cases, the permeability of a carbon monolith can vary primarily based on its bulk density. In some cases, permeability may also be affected by the spacing between fibers when forming the carbon fiber monolith and the degree of melting at the nodes. In some cases, the permeability of a carbon monolith is approximately 1 × 10⁻⁶. -10 m 2 ~Approx. 8.5×10 -11 m 2 It may be within the range of 9.8 × 10. In some examples, the transparency range is approximately 9.8 × 10. -11 m 2 It may be less than 9.5 × 10⁻⁶. In other examples, the permeability is approximately 9.5 × 10⁻⁶. -11 m 2 Less than approximately 9.0 × 10 -11 m 2 Less than, or approximately 8.8 × 10 -11 m 2 It may be less than 1. In some examples, the permeability of a carbon monolith is approximately 1 × 10⁻⁶. -10 m 2 ~Approx. 9.8×10 -11 m 2 It may also be within the range of approximately 9.8 × 10. -11 m 2 ~Approx. 9.5×10 -11 m 2 , about 9.5×10 -11 m 2 ~Approx. 9.3×10 -11 m 2 , about 9.3×10 -11 m 2 ~Approx. 9.0×10 -11 m 2 , about 9.0×10 -11 m 2 ~Approx. 8.8×10 -11 m 2 , or approximately 8.8 × 10 -11 m 2 ~Approx. 8.5×10 -11 m 2 One example is the intrinsic permeability of porous media such as carbon monoliths, which measures their ability to allow fluids to pass through under the influence of a pressure gradient. In practical applications, predicting permeability based on a specific porous structure is extremely important.

[0061] Furthermore, the properties of activated carbon fibers can be adjusted to reduce the temperature and energy required to desorb rare earth elements (REEs) from carbon monoliths. As will be described later, by applying an electric current to the carbon monolith, the electrical resistance of the carbon fibers within the monolith generates heat, raising its temperature and assisting the desorption process to remove REEs from the regenerative carbon monolith.

[0062] The first electric thermal swing adsorption device 410 includes a pitch supply 414. The pitch supply 414 may be the same as the pitch input flow 302. The pitch supply 414 contains REE present in the pitch. The pitch supply 414 may contain various different REE.

[0063] The pitch supply 414 flows along a supply channel 415, which includes a first pitch supply channel 415A. The pitch supply channel 415 is introduced into or received into the first chamber 412 via the first pitch supply channel 415A. Rare earth elements (REE) are adsorbed by the activated carbon monolith in the first chamber 412, thereby filtering the pitch supply 414. The first chamber 412 is connected to a pitch output stream 404, and the pitch supply 414 is discharged from the first chamber 412 via the first pitch output stream 404A. The pitch output streams 404 and 404A have reduced REE concentrations due to the adsorption of REE by the activated carbon monolith in the first chamber 412. In some embodiments, the pitch output streams 404, 404A may not contain the specific REE that the carbon monolith in the first chamber 412 was functionalizing, and may also contain additional REE that is removed by subsequent electrothermal swing adsorption devices (e.g., 320, 330) arranged in series. As described above, the pitch output streams 404, 404A are introduced into the second electrothermal swing adsorption device 320 and then into the third electrothermal swing adsorption device 330. After the pitch supply 414 has been discharged from all the electrothermal swing adsorption devices, the electrothermal swing adsorption device 410 can filter out the REE at a high rate.

[0064] The first electrothermal swing adsorption apparatus 410 further includes a purge 416. The purge 416 is a reservoir for a purge fluid used to desorb REE from a carbon monolith in a second chamber 413. In some embodiments, a purge gas is used in the desorption process. The purge 416 flows along a purge channel 417, which includes a first purge channel 417A. The purge 416 is introduced into or received into the second chamber 413 via the first purge channel 417A. REE is desorbed from the regenerated carbon monolith in the second chamber 413. Regeneration of the regenerated carbon monolith in the second chamber 413 is carried out by applying an electric current to the regenerated carbon monolith, causing it to heat up due to its electrical resistance and raising its temperature to 100°C to 150°C. This temperature range is determined depending on the properties of the carbon monolith in the second chamber 413, the REE that was captured, and the chemical modifications to the carbon monolith. In some embodiments, the purge fluid is discharged from the chamber before an electric current is applied to the carbon monolith. REE is desorbed from the carbon monolith and enters the purge 416. The REE may be discharged from the second chamber 413 through the first pitch flow 411A and then through the concentrated pitch flow 411.

[0065] The pitch flow 411 may be connected to a temporary storage container 418, which collects and stores REE obtained from the first electrothermal swing adsorption device 410, more specifically from the first chamber 412. As described above, the temporary storage container 418 can collect and store specific REE adsorbed by the carbon monolith in the first electrothermal swing adsorption device 410. In some embodiments, the temporary storage container 418 includes a flow path 419, which is in fluid communication with the pitch supply path 415 via a first flow path 419A and also in fluid communication with the purge path 417 via a second flow path 419B.

[0066] The first electrothermal swing adsorption device 410 operates continuously and periodically. In other words, a pitch supply 414 (e.g., pitch input flow 302) is continuously introduced into the first chamber 412 to adsorb REE from the pitch supply 414, and a purge 416 is continuously introduced into the second chamber 413 to desorb REE from the carbon monolith in the second chamber 413. When the activated carbon monolith in the first chamber 412 begins to reach a predetermined concentration / adsorption capacity (i.e., a state where it can no longer adsorb REE), the first electrothermal swing adsorption device 410 is switched over. That is, the carbon monolith in the first chamber 412 is regenerated by desorbing REE using the purge 416, and the carbon monolith in the second chamber 413 is activated by adsorbing REE from the pitch supply 414. Therefore, the first electric swing adsorption device 410 can continuously adsorb and desorb REE using the carbon monoliths in the first chamber 412 and the second chamber 413.

[0067] Figure 4B shows a schematic diagram of the first electric swing adsorption device 410 in the second configuration. The second configuration of the first electric swing adsorption device 410 is the reverse of the first configuration. Although Figure 4B shows a schematic diagram of the first electric swing adsorption device 410 in the second configuration, the electric swing adsorption devices 320 and 330 in the second configuration are the same as the schematic diagram of the first electric swing adsorption device 410 in the second configuration.

[0068] The first electrothermal swing adsorption device 410 in the second configuration includes a first chamber 412 and a second chamber 413. In the second configuration of the illustrated first electrothermal swing adsorption device 410, the first chamber 412 includes a regenerating carbon monolith for desorbing REE, and the second chamber 413 includes an activated carbon monolith for adsorbing REE. Previously, the regenerating carbon monolith of the first chamber 412 was the activated carbon monolith of the first chamber 412 in the first configuration, and the activated carbon monolith of the second chamber 413 was the regenerating carbon monolith of the second chamber 413 in the first configuration. In this way, the first chamber 412 and the second chamber 413 operate periodically, continuously adsorbing and desorbing REE.

[0069] The first electric swing adsorption device 410 includes a pitch supply 414. The pitch supply 414 may be the same as the pitch input flow 302. The pitch supply 414 contains REE present in the coal pitch.

[0070] The pitch supply 414 flows along the pitch supply channel 415, which includes a second pitch supply channel 415B. The pitch supply channel 415 is introduced into or received into the second chamber 413 via the second pitch supply channel 415B. REE is adsorbed by the activated carbon monolith in the second chamber 413, thereby filtering the pitch supply 414. The activated carbon monolith in the second chamber 413 is the same as the regenerative carbon monolith in the second chamber 413 in the first configuration. The second chamber 413 is connected to the pitch output stream 404, and the pitch supply 414 is discharged from the second chamber 413. The pitch output stream 404 may have a reduced concentration of REE or may be REE-free because the REE is adsorbed by the activated carbon monolith in the second chamber 413. In some embodiments, the pitch output streams 404, 404A may not contain the specific REE that the carbon monolith in the first chamber 412 was functionalized with, and may also contain additional REE that is removed by subsequent electrothermal swing adsorption devices (e.g., 320, 330). As described above, the pitch output stream 404 may be introduced into a second electrothermal swing adsorption device 320, followed by a third electrothermal swing adsorption device 330. By processing the pitch supply 414 as described above, a significant reduction in REE can be achieved.

[0071] Regeneration of the regenerative carbon monolith in the first chamber 412 is performed by applying an electric current to the regenerative carbon monolith, causing it to heat up due to its electrical resistance and raising its temperature to 100°C to 150°C. This temperature range depends on the properties of the carbon monolith in the first chamber 412, the REE desorbed from the carbon monolith, and the chemical modifications to the carbon monolith. In some embodiments, a purge fluid is discharged from the chamber before an electric current is applied to the carbon monolith. REE is desorbed from the carbon monolith. The REE concentrated during the purge 416 can be transferred from the first chamber 412 through the concentrated pitch flow 411 by a second concentrated pitch flow 411B.

[0072] Figure 5 is a flowchart of method 500 for extracting rare earth elements from a coal deposit using an electrothermal swing adsorption system. In some examples, method 500 may include a step 502 to liquefy the coal deposit, which contains coal and clay ore, to form pitch. Liquefaction may include direct coal liquefaction (DCL), which involves bringing coal into direct contact with a catalyst under high temperature and pressure with hydrogen (H2) added in the presence of a solvent to form a stock product, which can be filtered or treated to extract rare earth elements (REE) and further purified into products such as liquid fuel. The latter two-step approach, namely converting coal into synthesis gas and producing a liquid from that synthesis gas, is called indirect coal liquefaction (ICL). In some examples, the liquefaction process may include crushing the coal deposit to suspend coal solids in a fluid with about 6% to about 8% water content. As an example, the crushed coal deposit may contain particle sizes from about 0.5 μm to about 50 μm. However, other particle sizes may be used depending on the liquefaction treatment and functionalization of the carbon fibers.

[0073] In some examples, Method 500 may include step 504 of supplying pitch to the chamber of an electrothermal swing adsorption apparatus. The pitch may contain relatively low concentrations of REE. In some examples, the pitch may contain a REE concentration of about 400 ppm. Method 500 may further include step 506 of adsorbing rare earth elements by a carbon monolith in the chamber. The carbon monolith contains coal-based activated carbon fibers. The carbon monolith may function as a filter and / or be functionalized to adsorb multiple REEs or specific REEs. In some examples, the step of adsorbing rare earth elements by a carbon monolith in the chamber includes moving the carbon monolith through the pitch.

[0074] In some examples, method 500 may include step 508 of discharging pitch from the chamber of the electrothermal swing adsorption apparatus. The pitch may exhibit a low concentration of REE. In some examples, method 500 may further include step 510 of applying an electric current to the carbon monolith in the chamber to raise the temperature of the carbon monolith and desorb rare earth elements from the carbon monolith. In some examples, after desorption, the pitch may contain a concentration of approximately 8000 ppm or higher.

[0075] As used herein, the terms “approximately” or “substantially” refer to a tolerance of ±10% or ±5% for the value modified by “approximately” or “substantially.” Furthermore, terms such as “less than,” “less than or equal to,” “greater than,” “more than,” and “greater than or equal to” include the modified value as the endpoint of their range.

[0076] While the above description uses specific terminology for illustrative purposes, those skilled in the art will understand that specific details are not necessarily required to carry out the described embodiments. Therefore, the descriptions of the specific embodiments provided herein are presented for illustrative and illustrative purposes only and are not intended to be exhaustive or to limit the form of disclosure. Those skilled in the art will understand that many modifications and variations are possible based on the above teachings.

[0077] Various embodiments have been described in this specification based on specific examples. However, those skilled in the art will recognize that many modifications are possible without departing from the spirit and scope of the embodiments disclosed herein. The embodiments described in the following claims are intended to encompass all changes and modifications without departing from the spirit of this disclosure.

Claims

1. A method for separating rare earth elements from coal and clay ore, A process of liquefying raw coal to form pitch or pitch resin, A step of filtering the pitch or pitch resin to capture rare earth elements, A step of purifying the pitch or pitch resin to produce mesophase pitch, A step of subjecting the mesophase pitch or the pitch resin to a low-crystallinity spinning process to form carbon fibers, A method that includes this.

2. The method according to claim 1, wherein the rare earth element comprises at least one of gallium, germanium, cerium, lanthanum, neodymium, praseodymium, scandium, yttrium, dysprosium, terbium, samarium, ytterbium, europium, promethium, gadolinium, holmium, lutetium, thulium, and erbium.

3. The method according to claim 1, wherein the pitch or pitch resin includes isotropic pitch.

4. The method according to claim 1, wherein the step of filtering the pitch or pitch resin includes removing impurities and water and physically separating and detecting the rare earth elements.

5. The method according to claim 4, further comprising the step of rehydrating the pitch or pitch resin to a moisture content of about 6% to about 8%.

6. The method according to claim 1, further comprising the step of selecting the rare earth elements as heavy rare earth elements or light rare earth elements.

7. The method according to claim 1, further comprising the step of modifying the carbon fibers to bond with or electrostatically interact with rare earth elements.

8. The method according to claim 7, wherein the step of modifying the carbon fibers to bond with or electrostatically interact with the rare earth elements includes attaching a mineral-binding protein or a lanthanide-binding protein to the carbon fibers.

9. The method according to claim 7, wherein the step of modifying the carbon fiber to bond with or electrostatically interact with the rare earth element includes increasing the negative charge of the carbon fiber to increase the electrostatic interaction with the rare earth element.

10. A method for extracting rare earth elements from coal deposits using an electrothermal swing adsorption system, A process of liquefying a coal deposit containing coal and clay ore to form pitch, The process of supplying the aforementioned pitch to the chamber of the electric thermal swing adsorption device, The process involves adsorbing the rare earth elements using a carbon monolith within the chamber, A step of discharging the aforementioned pitch from the chamber of the electric heating swing adsorption device, A method that includes this.

11. The method according to claim 10, further comprising the step of applying an electric current to a carbon monolith in the chamber to raise the temperature of the carbon monolith and desorbing the rare earth element from the carbon monolith.

12. The method according to claim 10, wherein the step of adsorbing the rare earth elements by a carbon monolith in the chamber includes moving the carbon monolith in the pitch.

13. The method according to claim 10, wherein the carbon monolith comprises coal-based activated carbon fibers.

14. The method according to claim 10, wherein the liquefaction treatment includes crushing the coal deposit and suspending the coal solids in a fluid having a moisture content of about 6% to about 8%.

15. The method according to claim 14, wherein the crushed coal deposit has a particle size of about 0.5 μm to about 50 μm.

16. A system for extracting rare earth elements from coal deposits, A first chamber containing at least one carbon monolith, A second chamber containing at least one carbon monolith, Equipped with an electric heating swing adsorption device, The electric swing adsorption device is configured to accept a supply of coal-based pitch containing at least one rare earth element. Each carbon monolith of the electric heating swing adsorption device contains coal-based activated carbon fibers configured to capture the rare earth elements. system.

17. The system according to claim 16, wherein the at least one carbon monolith in the first chamber captures the rare earth element, and the at least one carbon monolith in the second chamber desorbs the rare earth element at the same time that the at least one carbon monolith in the first chamber releases the rare earth element.

18. The system according to claim 16, wherein the first chamber and the second chamber operate periodically to continuously capture and release rare earth elements, and while capture is taking place in one of the first chamber or the second chamber, release is taking place in the other of the first chamber or the second chamber.

19. The system according to claim 16, wherein each carbon monolith is functionalized to adsorb a specific rare earth element.

20. The system according to claim 16, wherein the coal-based activated carbon fibers are melt-blown from an isotropic pitch.

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