Graphite purification system and method

Abstract

A graphite purification system comprises: a vessel adapted to contain graphite particles, the vessel comprising an induction coil for heating the vessel; and a cooling system for cooling the graphite purification system, whereby the cooling system is adapted to also cool the graphite particles. The purification system may be a continuous or batch system, and the vessel may be formed at least partially from graphite. The invention also proposes a method of purifying graphite particles, the method comprising: providing a container at least partially formed from graphite; filling graphite particles into the container; inductively heating at least a portion of the vessel, thereby heating the graphite particles in physical contact with the vessel; and cooling the vessel and the graphite particles.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 369,257, filed on July 25, 2022, and entitled “Graphite Purification System and Method,” the teachings of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present invention relates to graphite purification systems and methods, and more particularly to furnaces heated by magnetic induction that exhibit increased efficiency in converting electrical energy into usable thermal energy. Background Art

[0004] As battery technology has advanced, such as in electric vehicles, graphite has been found to be a useful conductor in these types of batteries. A key component of lithium-ion batteries is graphite, which is the main material used in one of the two electrodes, called the anode. Normally, when the battery is charged, lithium ions flow from the cathode to the anode through the electrolyte buffer that separates the two electrodes.

[0005] In order to be usable, naturally occurring graphite must be processed to remove impurities, such as those typically present in graphite ores. These impurities include, for example, metal hydrides, oxides, and metal silicates. The grinding process typically grinds a graphite concentrate, which is then formed into spherical particles. In some processes, the spheroidized particles are purified by an acid leaching process, which can be harmful to the environment. In many areas around the world, the acid leaching process unfortunately results in environmental degradation.

[0006] As an alternative, purification methods have been developed that specifically use high temperature furnaces. Although environmentally harmful acid leaching or alkali burning is not used, the inherent high temperatures and inefficient cooling lead to increased energy costs and relatively long purification process times. For example, resistive heating can be used in an oven, whereby the graphite is heated in batches in a horizontal or vertical orientation in an effort to remove impurities. But again, these methods are always batch methods and require relatively high temperatures and relatively long process times, so the energy costs are relatively high. In addition, these methods require relatively long equipment cooling times, which increases the process time. Therefore, these types of challenges continue to drive continuous improvements in the graphite purification industry. Summary of the invention

[0007] A graphite purification system includes: a container suitable for containing graphite particles;

[0008] a magnetic induction coil for heating the container; and a cooling system for cooling the graphite purification system, whereby the cooling system is adapted to also cool the graphite particles. The purification system may be a continuous or batch system, and the container may be formed at least in part of graphite. The present invention also provides a method for purifying graphite particles, the method comprising: providing a container at least partially formed of graphite; loading graphite particles into the container; inductively heating at least a portion of the container, thereby heating the graphite particles in physical contact with the container; and cooling the container and the graphite particles. The cooling system may include: a vertical column operably connected to the container for vertical flow of graphite particles through the purification system; a cooling jacket wrapped around at least a portion of the vertical column; and a coolant circulating through the cooling jacket. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a first exemplary embodiment of a vertical continuous graphite purification system according to the present invention.

[0010] Figure 2 is a perspective view of a second exemplary embodiment of a vertical continuous graphite purification system according to the present invention.

[0011] Figure 2A yes Figure 2 A side view of an embodiment of the invention.

[0012] Figure 2B is along Figure 2A A cross-sectional view taken along line BB.

[0013] Figure 2C yes Figure 2 Front view of an implementation scheme of FIG.

[0014] Figure 2D is along Figure 2C A cross-sectional view taken along line CC.

[0015] Figure 2E yes Figure 2A Bottom view of .

[0016] Figure 2F yes Figure 2C Bottom view of .

[0017] Figure 3 This is a first embodiment of the cooling system of the present invention.

[0018] Figure 4 is a first schematic diagram of a batch purification system according to the present invention.

[0019] Figure 5 is a perspective and exploded view of a second exemplary batch purification system according to the present invention.

[0020] Figure 5A yes Figure 5 Cross-sectional view of a batch purification system.

[0021] Figure 5B is a cross-sectional view of a batch purification system in a stacked configuration.

[0022] Figure 6 is a schematic diagram of a third exemplary batch purification system according to the present invention.

[0023] Fig. 6A yes Figure 6 Side view of the batch purification system.

[0024] Figure 6B It was taken along line BB Fig. 6A Cross-sectional view of a batch purification system.

[0025] Figure 6C yes Figure 6 Bottom view of the crucible shown.

[0026] Figure 7 is a schematic diagram of a fourth batch purification system according to the present invention.

[0027] Figure 8 is a perspective view of a first hopper and a second hopper in a vertical continuous graphite purification system according to the present invention.

[0028] Fig. 8A yes Figure 8 Side view of the hopper.

[0029] Figure 8B yes Figure 8 Front view of the hopper.

[0030] Figure 8C yes Figure 8 A bottom view of the device is shown, showing the connecting flange.

[0031] Fig.8D yes Figure 8 A bottom view of the device is shown showing the inert gas inlet for the second hopper.

[0032] Fig. 9 yes Figure 2 An exploded view of an implementation scheme of FIG.

[0033] Fig.10 yes Figure 2 A perspective view of an embodiment of the invention.

[0034] Fig.11 A perspective view of an exemplary induction coil and heater of a vertical column of the present invention is shown.

[0035] Fig.11A yes Fig.11 Side view of a graphite tube or vertical column.

[0036] Fig. 11B yes Fig.11 A second side view of the graphite tube or vertical column, emphasizing the induction coil.

[0037] Fig. 11C yes Fig.11 A cross-sectional view of a graphite tube or vertical column.

[0038] Fig.11D The power supply and Fig.11 Schematic diagram of the electrical connections of the induction coil of a graphite tube or vertical column.

[0039] Fig.11E yes Fig.11 A top view of the connecting flange of a graphite tube or vertical column, also schematically showing the power connection to the induction coil.

[0040] Fig.12 A perspective view of an exemplary vertical column or graphite tube feeder of the present invention is shown.

[0041] Fig. 12A yes Fig.12 Side view of a vertical column or graphite tube feeder.

[0042] Fig. 12B yes Fig.12 A cross-sectional view of a vertical column or graphite tube feeder.

[0043] Fig. 12C yes Fig.12 A top view of a vertical column or graphite tube feeder.

[0044] Fig.12D yes Fig.12 Bottom view of a vertical column or graphite tube feeder.

[0045] Fig.13 is a perspective view of an exemplary jacketed cooling funnel of the present invention.

[0046] Fig.13A yes Fig.13 Side view of the jacketed cooling funnel.

[0047] Fig. 13B yes Fig.13 Rear view of the jacketed cooling funnel.

[0048] Fig. 13C is along Fig. 13B A cross-sectional view of the jacketed cooling funnel taken along line AA.

[0049] Fig.13D is a top view of the vacuum flange that secures the top of the jacketed cooling funnel. Fig.13E yes Fig.13Bottom view of the jacketed cooling funnel.

[0050] Fig.14 A second exemplary cooling system according to the present invention is shown.

[0051] Fig.15 A third exemplary cooling system according to the present invention is shown.

[0052] Fig.16 Shows Figure 1 Side view of a vertical continuous graphite purification system.

[0053] Fig.16A Shows Figure 1 An embodiment of a mixer or conveyor of a vertical continuous graphite purification system.

[0054] Fig. 16B Shows Fig.16 Cross-sectional view of a vertical continuous graphite purification system.

[0055] Fig. 16C Shows Fig.16 A second embodiment of a mixer or conveyor for a vertical continuous graphite purification system.

[0056] Fig.17 A fourth exemplary cooling system according to the present invention is shown. DETAILED DESCRIPTION

[0057] Non-limiting definition

[0058] The terms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0059] The term "about" or "approximately" applies to all values, whether or not explicitly stated. These terms generally refer to a range of values ​​that one skilled in the art considers equivalent to the stated value (i.e., having the same function or result). In many cases, these terms may include numbers rounded to the nearest significant figure.

[0060] The term "adapted to" describes hardware, software, or a combination of hardware and software that is capable of, able to accommodate, made, or suitable for performing a given function.

[0061] The term "another," as used herein, is defined as at least a second or more.

[0062] The phrase "associated with..." and its derivatives may mean to include, be included within, be interconnected with, contain, be contained within, connect to or be connected with, be coupled to or be coupled with, be able to communicate with, cooperate with, interleave, juxtapose, be close to, be bound to or be bound with, have, have the characteristics of, have a relationship with, etc.

[0063] phrase" 、 ......and <n> At least one of "or"< / n> 、 ...... <n> or at least one of their combinations" or "< / n> 、 ...and / or <n>" is defined by the applicant in the broadest sense, unless the applicant explicitly states otherwise, superseding any other implicit definition above or below, to mean one or more elements selected from the group consisting of A, B... and N, that is, any combination of one or more of elements A, B... or N includes any one of the elements alone or in combination with one or more other elements, which other elements may also include additional elements not listed in combination.

[0064] The term "connected" and its derivatives include direct and indirect connections.

[0065] When used in this specification, the terms "comprise" and / or "include" specify the existence of stated features, steps, operations, elements and / or components, but do not preclude the existence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0066] The term "configured to" describes hardware, software, or a combination of hardware and software that is adapted, set up, arranged, constructed, composed, constructed, designed, or has any combination of these characteristics, to perform a given function.

[0067] The term "coupled" is defined as connected, although not necessarily directly, and not necessarily mechanically.

[0068] As used herein, the terms "including," "comprising," and "having," are defined as comprising (ie, open language).

[0069] The term "or" is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless specified otherwise or clear from context, "X employs A or B" is intended to mean any of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, then "X employs A or B" is satisfied in any of the foregoing instances. Furthermore, the articles "a" and "an" as used in this application and the appended claims should generally be construed to mean "one or more" unless specified otherwise or clear from context in the singular.

[0070] The terms "substantial" and "substantially" mean that when various components are compared to each other, the compared components are equal or close enough in size that a person skilled in the art would consider them to be the same. As used herein, "substantial" and "substantially" are not limited to a single dimension, and specifically include a range of values ​​for those components being compared. Above and below the range of values ​​(e.g., "+ / -" or greater / lesser or larger / smaller), include a range of variations that a person skilled in the art would know to be a reasonable tolerance for the components.

[0071] Note that not all activities described above in the general description or in the embodiments are required, that a portion of a specific activity may not be required, and that one or more additional activities may be performed in addition to those described. Further, the order in which the activities are listed is not necessarily the order in which they are performed.

[0072] Vertical continuous production system

[0073] In a first embodiment of the present invention,< / n> Figure 1 As shown, a vertical feed furnace 10 is provided, which is preferably heated by magnetic induction. According to the present invention, the heating, purification and cooling of graphite particles, such as spheroidized graphite particles, are enhanced by a vertical graphite feed system or vertical feed furnace 10. The vertical graphite feed system 10 can also be, for example, Figure 1 , Figure 2 and Figure 8 Continuous vertical graphite feed system 10 is shown. It should be understood that the mass flow rate of graphite, defined by the change in mass units over time, can be iteratively determined based on the applied induction heat (described below) and based on a predetermined desired purity level. An exemplary mass flow rate is provided at 5 kg per hour. It should be understood that the mass flow rate can be changed based on design variables when optimizing design criteria.

[0074] like Figure 1 , Figure 2 and Figure 8 As shown, the first feed hopper or first open hopper 12 is preferably conical and is located at the top end 14 of the furnace 10 for receiving spheroidized graphite fed into the first open hopper 12 or the top of the first feed hopper 12. A first sliding door 16 is located at the bottom of the first feed hopper 12 to automatically or manually adjust and facilitate the gravity transfer of graphite particles through the first feed hopper 12.

[0075] The second feed hopper 18 or second environmentally controlled hopper 18 is also preferably conical, environmentally controlled and operatively sealed and is positioned immediately below the first feed hopper 12 whereby the graphite particles flowing from the first feed hopper 12 flow through the first sliding door 16 into the top of the second feed hopper 18 for processing therein. A vacuum flange 21 may be provided at the top of the second feed hopper 18 to facilitate environmental control of the second feed hopper 18. An oxygen scavenger, such as carbonized ascorbic acid, may be integrated into the second feed hopper 18 so that oxygen is at least reduced or removed from the flow of graphite particles as the graphite particles pass through, for example, a bed of carbonized ascorbic acid, for example, before entering a furnace below. Reaction of the graphite with oxygen is thereby eliminated or at least mitigated. Figure 8 As shown, inert gas may be injected into the second feed hopper 18 through an inert gas inlet 19 to aid in fluidization of the graphite particles as they flow through the hopper 18. A second sliding gate 20 is located at the bottom of the second feed hopper 18 to automatically or manually regulate and facilitate gravity transfer of the graphite particles through the second feed hopper 18.

[0076] Refer again Figure 1 and Figure 8 During operation of the system 10, a flow tube or conduit 22 is operatively connected to the second sliding gate 20 to facilitate gravity flow of graphite particles exiting the second feed hopper 18 to the system below. Figure 1 and Figure 8 As shown, a first connecting flange 24 is attached to the bottom of the second feed hopper 18 for connecting the second feed hopper 18 to the flow tube 22, thereby facilitating the flow of graphite particles therethrough. Figure 2 and Figures 8 to 10 As shown, the connecting flange 24 may instead be connected directly to a vertical column or graphite feed tube 30, again facilitating the flow of graphite particles therethrough.

[0077] exist Figure 1 In the exemplary embodiment of the present invention, a mixer motor 26 is radially spaced outwardly from the first feed hopper 12 and is fixed within the structure 10 for rotatably operating the mixer, as described below. A second flow tube or conduit 28 supports the motor 26 and extends downwardly along the hoppers 12 and 18 to facilitate operative communication between the motor 26 and the mixer, as described below. Figure 1 As further shown, a junction 70 is defined at the intersection of the first conduit 22 and the second conduit 28, respectively, whereby the interiors of each conduit overlap one another in operable communication therewith.

[0078] Refer again Figure 1 and Fig.11 In the exemplary embodiment of the present invention, the graphite feed tube 30 extends from the second flange 36 and is operably connected to the bottom end of the second flow tube 26 or the connecting flange 24 through the second flange 36, thereby providing a vertically oriented internal plenum 32 defined by the graphite feed tube 30. Alternatively, referring to Figure 2 and Fig.11 , the graphite flow tube 30 may be directly connected to the second feed hopper 18 via the second flange 36 .

[0079] Refer again Figure 1 , Fig.11 and FIG. 11A to FIG. 11E , the flow of graphite particles can be directed from the first tube 22 into the graphite feed tube 30 to heat the flow of graphite particles therein. An insulating material 34, such as zeolite, is preferably coated around the upper portion 72 of the graphite tube 30 for reflecting and retaining radial heat generated within the internal plenum 32. In addition, a plurality of cooling / heat sinks 74 can be formed around the bottom portion 76 of the graphite feed tube 30 in a coaxial relationship with the graphite feed tube 30 for cooling the graphite particles as they pass through the bottom portion 76. For example, an exemplary magnetic induction coil 38, which can be manufactured by Ultraflex Power Technologies of New York or California, is coiled around the insulating material 34 for heating the internal plenum 32.

[0080] like Figure 1 , Figure 2 and Fig.12 As shown, the jacketed titanium container 44 provides a cylindrical and annular housing positioned around the graphite feed tube 30 for cooling the portion of the graphite feed tube 30 that is not heated by the coil 38. As further described below, a cooler can be connected to the jacketed container 44 in a known manner for cooling thereof. A power line 40 extends through the titanium container 44 and provides electronic communication between the power source 42 and the induction coil 38 for energizing the coil 38.

[0081] Reference Fig.10 and Figures 12 to 12D A connecting column 45 extends from the top of the container 44 and the graphite tube feeder 30 for connecting the tube feeder to the flange 24 at the bottom of the second sliding door 20. A connecting flange 47 is fixed to the bottom of the container 44 for fixing the container 44 and the graphite tube feeder 30 to the rotary valve 60.

[0082] Reference Figure 1 , and with reference to the internal plenum 32, a rotary mixer / screw conveyor 46 driven by the mixer motor 26 may be centrally disposed within the internal plenum 32 for transferring graphite particles from the top to the bottom of the graphite feed tube 30. It should be understood that just as the graphite feed tube 30 is formed of graphite, the rotary mixer 46 is also preferably formed of graphite. It is believed that when the graphite feed tube 30 and the rotary mixer 46 are formed of graphite, they each act as a susceptor by absorbing the magnetic flux lines inherent in induction heating and amplifying the reciprocal magnetic dipole activity, thereby enhancing and promoting the heat generated within the upper portion 72 of the graphite feed tube 30. By enhancing the heat applied to the graphite particles within the graphite feed tube 30, volatile organic compounds (VOCs) and metallic impurities such as metal hydrides and metal silicates (but not limited thereto) are believed to be cooked off at about 500°C and about 1700°C to 1800°C, respectively.

[0083] like Fig.16 As further shown, the rotating inline mixer 46 can be formed as a screw conveyor and can also be constructed to contain graphite. It has been found that the rotating design and graphite construction can provide additional heating and more efficient heat transfer to the graphite powder and also aid in mixing the graphite powder with an inert gas or other reactive gas. The mixer 46 helps to adequately agitate the graphite powder during high temperature heating.

[0084] Likewise, Figure 1 As shown schematically, the third exhaust conduit 50 also partially defines the junction 70 and extends upward from the second tube or conduit 28, so that the graphite feed tube 30, the second tube 28 and the third exhaust conduit 50 are in fluid communication to exhaust impurities volatilized from the heated graphite particles. Therefore, VOCs and metal plasma vapors formed from impurities boiled off from the graphite particles can be managed at a wet (e.g., aqueous) scrubber that is in fluid communication and operative communication with the exhaust conduit 50. By exhausting or venting the VOCs and metal plasma released from the heated graphite feed tube 30, metal silicates and hydrides and other impurities can be collected at the scrubber in a known manner or otherwise managed.

[0085] Reference Figure 1 , a jacketed cooling tower 52 may be connected to the bottom of the graphite feed tube 30, whereby the graphite particles exiting the graphite feed tube 30 are immediately cooled in a number of stages defined in the cooling tower 52. Although not limited, the first upper stage 54 of the jacketed cooling tower 52 may provide a fluid flow of a coolant (such as water) into and out of the jacketed cooling tower 52. A second intermediate stage 56 of the cooling tower 52 may provide temperature control of the graphite particles (e.g., via a thermocouple). In other words, a graphite particle temperature controller 51 (such as a thermocouple) may be housed within the purification system, in operable communication with the cooling jacket of the jacketed cooling tower 52, for example, to measure the temperature of the graphite particle flow, thereby adjusting the flow rate of the coolant determined by a preset control setting. The third bottom stage 58 of the cooling tower 52 may provide regulation of the fluid flow of the coolant into and out of the cooling tower 52. It should be understood that the various stages of the cooling tower 52 may be interchangeable, as long as the cooling function is retained within the cooling tower 52.

[0086] Go to Figure 2 and FIG. 2A to FIG. 2F In another exemplary embodiment of system 10, cooling tower 52 may be omitted from purification system 10, whereby cooling is achieved by passing the graphite particles through an unheated portion of graphite feed tube 30 and then passing the graphite particles through a jacketed cooling discharge hopper, as described below.

[0087] refer to Figure 3 , provides a schematic diagram of an exemplary cooling system 310 in operative communication with the purification system 110 (or work head 110). A coolant reservoir 312 (such as a water tank 312) is in fluid communication with the purification system 110 and various components of the cooling system 310. Figure 3 As shown, a pump 314 in fluid communication with a coolant reservoir 312 pumps the coolant through the system 310. A 5 ton chiller 316 receives water or coolant from the coolant reservoir 312 and provides the cooled coolant directly to the power source 42, the purification system 110, and the induction coil 38 to cool them. Heated coolant 318 is transferred from the power source 42, the workhead or purification system 110, the electric coil 38, and other heat sources to the heat exchanger 320 for heat transfer and cooling of the coolant 318. A 10 ton chiller 322 is in fluid communication with the heat exchanger 320 to further cool the system coolant 318 during operation of the system 110. Finally, the cooled coolant 318 is then recirculated from the chiller 322 back to the heat exchanger 320 for transfer back to the coolant reservoir 312 and recirculated back through the system 310.

[0088] To further illustrate the cooling system 310, Fig.14 A second exemplary embodiment of a cooling system 310 is shown in FIG. Fig.14 As shown, the heated coolant 318 (H in) exiting the workhead or purification system 110 enters the heat exchanger 320 and, after heat exchange (H out), enters the chiller 322 for cooling. After cooling, the coolant 318 flows again to and through the heat exchanger 320 as the coolant input (C in) and the coolant output (C out). This cooling flow from the chiller 322 provides a coolant reservoir for thermodynamic communication with the coolant flow from the workhead or purification system 110. The coolant 318 (C out) exiting the heat exchanger 320 is then recycled back to the tank 312 to be drawn out again as the cooling process continues.

[0089] In yet another embodiment of the cooling system 310, Fig.15 A third exemplary embodiment of a cooling system 310 is shown. Fig.15 As shown, heated coolant 318 (H in) enters heat exchanger 320 and is cooled therein before exiting as "heated coolant output" (H out). The cooled "H out" is then recirculated back to tank 312 to be drawn out again as the cooling process continues. A closed coolant loop 360 is in thermodynamic communication with heat exchanger 320 and is defined by a continuous coolant flow input (C in) pumped from 10-ton chiller 322 into heat exchanger 320 to provide a continuous cooling reservoir in heat exchanger 320. As heat is transferred to "C in", it exits heat exchanger 320 as coolant output (C out) to circulate back to 10-ton chiller 322 where it is cooled. Once cooled, the coolant exits as "C in" to again provide cooling within heat exchanger 320.

[0090] In yet another embodiment of the cooling system 310, Fig.17 A fourth exemplary embodiment of a cooling system 310 is shown. A 5 ton chiller 316 is in fluid and thermodynamic communication with a coolant 318 and a cold water reservoir 312. A first chiller pump 315 pumps a coolant 318 (e.g., water) into and out of the cold water reservoir or tank 312 to facilitate cooling of the water 318, thereby maintaining a continuous cooling temperature at which the system 110 operates. A second pump 317 pumps water 318 from the cold water reservoir 312 to the coil 38 and the workhead or purification system 110. As the coolant 318 leaves the coil 38, it is continuously pumped to the heat exchanger 320 for heat transfer therein. A second coolant 324 is pumped from the 10 ton chiller 322 to the heat exchanger 320 for cooling the system coolant 318. As shown in FIG. Fig.17 As shown, when the second coolant 324 is pumped in the closed loop 326 defined between the heat exchanger 320 and the 10-ton cooler 322, the 10-ton cooler 322 is in thermodynamic communication with the heat exchanger 320, thereby facilitating heat transfer between the system coolant 318 and the second coolant 324. Therefore, the second coolant 324 is cooled as it is pumped from the heat exchanger 320 back to the 10-ton cooler 322.

[0091] Refer again Figure 1 , a rotary valve 60 is fluidly and operatively connected to the bottom end of the cooling tower 52 for controlling the release of the flow of purified graphite particles moving therethrough. Although not shown, the rotary valve 60 can be controlled by a variable frequency drive (VFD) in a known manner. A third sliding door 66 is housed at the bottom of the rotary valve 60 and is used to automatically or manually regulate and facilitate the gravity transfer of graphite particles through the rotary valve 60.

[0092] like Figure 1 , Figure 2 and Figures 13 to 13E As shown, a jacketed discharge hopper 64, also preferably conical in shape, is connected to the bottom of the rotary valve 60. Also, as with the cooling tower 52, the discharge hopper 64 is in fluid communication with a cooling source, such as a heat exchanger or chiller, to facilitate efficient and rapid cooling of the purified graphite particles. A coolant inlet 78 is in fluid communication with the discharge hopper 64 to provide cooling of the graphite particles flowing therethrough. A coolant outlet 80 (see below) positioned adjacent the fourth sliding door 68 provides for the discharge of coolant or water from the hopper 64. As shown in FIG. Fig.13 As shown, a second gas inlet 65 can be used to inject an inert gas into the graphite flowing through the discharge hopper 64 to assist in discharging graphite particles therefrom. A fourth sliding gate 68 is housed at the bottom of the discharge hopper 64 and is used to automatically or manually regulate and facilitate gravity transfer of purified graphite spheroidized particles from the system 10.

[0093] As described above, the hoppers 12, 18 and 64 can be formed of stainless steel or other suitable materials. The sliding doors 16, 20, 66 and 68 can be formed of stainless steel or other suitable materials. The jacketed titanium container 44 can of course be formed of titanium. All tubes or conduits, except the graphite feed tube 30, can also be formed of stainless steel. As described above, the rotary mixer / conveyor 46 and the graphite feed tube 30 can be molded of graphite or formed of metal to provide the enhanced heating benefits described above. A known control system can be used to achieve automatic control of the system 10 in a known manner.

[0094] Batch System

[0095] Further according to the present invention, and as Figures 4 to 7 As illustrated, graphite particles may be heated in a crucible in a batch system 110. Figure 7 As shown, the first crucible 112 is contained in a ventilated oven 114 for inductively heating the container or crucible 112 (heating container). An induction coil 116 is coiled around the container or crucible 112 for heating the crucible 112. A power cord 118 connects a power source 120 to the coil 116 to provide inductive heat to the crucible 112. Fig. 7A As shown, copper tubes 117 house wires 118 and are secured to oven 114 via compression fittings 115 of the copper tubes. Mounting flanges 113 are glued to washers 123, which are glued or otherwise secured to oven 114. A corresponding plexiglass tube 119 extending through mounting flanges 113 may be continuously secured to each copper tube 117 extending into oven 114, thereby providing a continuous conduit for wires 118 that power induction coils 116 to heat crucibles 112. Crucibles 112 are preferably made of graphite, as are graphite feed tubes 30 in vertical continuous production systems 10, so as to also take advantage of the thermal advantages of the reciprocating motion of magnetic dipoles when magnetic flux is sinusoidally generated. When the magnetic dipoles are alternated by AC current, the resulting sinusoidal energy pattern creates internal friction on the graphite-containing crucible and graphite-containing particles, thereby significantly improving thermal efficiency.

[0096] refer to Figure 5 In a second exemplary embodiment of a batch system, a second crucible 120 is formed in the same manner as the first crucible 112 and is also shaped the same as the first crucible 112, thereby facilitating stacking one graphite crucible on top of a second graphite crucible. When two or more crucibles are stacked in this manner, the additional heat generated can enhance the heating and purification process while optimizing energy costs. If desired, a cover 122 can be formed to fit over the opening of the top stacked crucible to retain heat within the top crucible during heating of the top crucible. A second coil 124 can also be wrapped around the second crucible 120 to provide magnetic induction heating thereto.

[0097] exist Figure 6 (And similarly in Figure 4 In a third exemplary embodiment of a batch system shown in Figure 2, the third batch system 210 includes a first crucible 212, which may include a square sawtooth circumference 214 surrounding an upper portion 216 of the first crucible 212. The sawtooth circumference facilitates venting from each crucible so formed, thereby releasing volatile compounds that are emitted from the graphite powder in the covered single or stacked crucibles. In addition, the gap provided by the sawtooth configuration facilitates the manipulation of the stacked hot crucibles by an automated fork during processing; for example, when a fork (not shown) is inserted through the gap of the bottom crucible, the adjacent upper crucible can be lifted from the bottom crucible.

[0098] Reference Figure 6 , Fig. 6A , Figure 6B and Figure 6C , the interior 218 of the first crucible 212 is defined by the wall 220 of the first crucible 212. A plurality of cavities or recesses 222 may be formed in a bottom portion 224 of the interior 218, whereby each cavity or recess 222 is formed to extend partially into the bottom portion 224 of the first crucible 212. Solid graphite rods 230, 232 may be inserted into the plurality of cylindrical cavities 222, whereby the solid graphite rods 230, 232 also function as thermomagnetic susceptors. Therefore, it is believed that the solid graphite rods 230, 232 may provide more heating surface for the graphite powder and also improve heating efficiency through reciprocal dipole activity within the solid graphite rods 230, 232.

[0099] In summary, the graphite crucible and optional graphite rods transfer heat to the graphite particles contained within the crucible when the corresponding crucible is inductively heated during the purification of graphite particles. As described above, induction heating causes magnetic flux lines to be absorbed by the graphite-containing crucible, rotating shaft, rods and other magnetic susceptors, and may be absorbed to a lesser extent (but not limited to) by the graphite particles and the resulting friction generated by the magnetic dipoles. Generally speaking, the graphite particles are heated primarily by conduction through the magnetic susceptors heated by the magnetic induction coils. In addition, heat transfer from the magnetic susceptors to the graphite particles further achieves effective heating. It should be understood that as an alternative to the crucible, other types of graphite supports, susceptors or containers (including rods, plates or cylinders) can also be molded from high purity graphite in a known manner.

[0100] Graphite purification method

[0101] In another aspect of the present invention, a method for purifying graphite is provided.

[0102] 1. In the first step, spheroidized graphite powder is preferably selected based on desired design criteria.

[0103] 2. The graphite powder is loaded into the top of the vertical continuous production process and fed by gravity to the induction heating furnace or graphite feed tube 30.

[0104] 3.Reference Figure 1 and Figure 2 , the graphite spheroidized particles or powder within the upper portion 72 of the graphite tube 30 are directly or indirectly heated by the induction coil 38. As described above, graphite can be introduced into the vertical continuous production process 10, whereby the graphite particles are inductively heated as they pass through the graphite feed tube 30 and through the upper portion 72 surrounded by the induction coil 38.

[0105] When heated in a temperature range of about 450° C. to 550° C., organic impurities may be released as volatile organic compounds (VOCs). When further heated in a temperature range of about 1700° C. to 2200° C., metal silicates, metal oxides, and other metal impurities or minerals may be released as pyrolytic metal plasma. Both VOCs and metal plasma may be released through vents 50 and directed to a wet scrubber to capture and manage these impurities.

[0106] Alternatively, if a batch system 110 is desired, such as Figures 4 to 7 As shown, at least one graphite crucible 112 or 212 (and optional graphite rod) can be inductively heated whereby, when charged with spheroidized graphite particles, for example, the particles physically contact the interior of the crucible 112 or 212 (and the surface of the optional graphite rod). Thus, the graphite particles are directly heated by contact with the heated container or heated crucible (and optional rod), and indirectly heated by the inductive heating of the crucible and the magnetic flux of the graphite particles contained in the crucible.

[0107] 4. Cooling the graphite particles by directing them through areas of the purification process that are not heated but rather cooled. These areas include areas within the graphite feed tube 30 of the vertical continuous feed production system 10, such as the bottom portion 76 surrounded by radial fins 74. In addition, the jacketed titanium container 44 will provide cooling in areas of the tube 30 that are not heated by the coils 38. Furthermore, if a cooling tower 52 is included, the jacketed tower will also cool the graphite particle stream in the same manner. Finally, the jacketed discharge hopper 64, which is also cooled by the cooling system 310,

[0108] (For example, Figure 5 ) will also cool the graphite particle stream in the same manner. For batch systems, to avoid reaction with atmospheric oxygen, the crucible 112 or 212 or other graphite-containing susceptor and container can be removed from induction heating by disconnecting the power source and physically moving the crucible to a cooler environment once the graphite temperature drops below about 500° C., or by moving the crucible to an oxygen-free environment. The graphite can be cooled by simply allowing the crucible and graphite particles to cool in the crucible, which is no longer being inductively heated.

[0109] Non-limiting Examples

[0110] The above descriptions of specific embodiments of the present invention are given for the purpose of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed, and many modifications and variations are possible in light of the above description. It should be understood that various omissions and / or substitutions of equivalents are contemplated when circumstances may suggest or provide expediency without departing from the spirit or scope of the claims of the present invention.

[0111] The description in this application should not be construed as implying that any particular element, step, or function is an essential or critical element that must be included in the scope of the claims. The scope of the patented subject matter is limited only by the claims as allowed. In addition, no claim invokes 35 U.S.C. § 112(f) with respect to any appended claim or claim element unless the exact words "means for" or "step for" are expressly used in a particular claim followed by a participle phrase identifying the function.

[0112] The above has described benefits, other advantages and solutions to problems for specific embodiments. However, the benefits, advantages, solutions to problems and any features that may cause any benefits, advantages or solutions to occur or become more significant do not constitute the key, necessary, inviolable or essential features of any or all claims.

[0113] After reading this disclosure, it will be appreciated by those skilled in the art that, for the sake of clarity, certain features described herein in the context of separate embodiments may also be provided in combination in a single embodiment. On the contrary, for the sake of brevity, various features described in the context of a single embodiment may also be provided individually or in any sub-combination. In addition, values ​​expressed as ranges include every value within the range.

[0114] The above discussion is intended to illustrate the principles and various embodiments of the present invention. Once the above disclosure is fully understood, many variations and modifications will become apparent to those skilled in the art. The appended claims are intended to be interpreted as covering all such variations and modifications.

Claims

1. A graphite purification system comprising: A container suitable for containing graphite particles; an induction coil for heating the container; and A cooling system for cooling the graphite purification system, whereby the cooling system is adapted to also cool the graphite particles, whereby the container is at least partially formed of graphite.

2. The graphite purification system of claim 1, wherein the graphite purification system is a continuous graphite feed system.

3. The graphite purification system according to claim 1, wherein the graphite purification system is a vertical continuous graphite feeding system.

4. The graphite purification system of claim 3, wherein the graphite purification system further comprises a first open-air hopper operably connected to a second environmental control hopper downstream of the first open-air hopper.

5. The graphite purification system of claim 4, wherein at least one of the first open air hopper and the second controlled environment hopper comprises a gas inlet for injecting a gas therein to fluidize the flow of graphite particles.

6. The graphite purification system of claim 1, wherein the cooling system comprises: a vertical column operably connected to the container for vertical flow of graphite particles through the cooling system; a cooling jacket surrounding at least a portion of the vertical column; and A coolant is circulated through the cooling jacket.

7. The graphite purification system of claim 6, wherein the coolant is selectively circulated through the cooling jacket.

8. The graphite purification system of claim 6, further comprising a graphite particle temperature controller that measures a temperature of graphite particles flowing therethrough, the graphite particle temperature controller being in operable communication with the cooling jacket.

9. The graphite purification system of claim 1, wherein the cooling system further comprises a graphite particle temperature controller for measuring the temperature of graphite particles flowing therethrough, the cooling system being in operable communication with the graphite particle temperature controller.

10. The graphite purification system of claim 1, wherein the graphite purification system is a batch system.

11. The graphite purification system of claim 10, wherein the batch system comprises: a first heating vessel for heating graphite particles; and A ventilated oven containing the first heating vessel.

12. The graphite purification system of claim 11, wherein the first heating vessel is a crucible formed at least in part from graphite, and the first heating vessel is induction heated.

13. The graphite purification system of claim 11, further comprising a second heating vessel stacked on the first heating vessel.

14. The graphite purification system of claim 13, wherein each of the first heating vessel and the second heating vessel is a crucible formed at least in part from graphite, and each heating vessel is induction heated.

15. The graphite purification system of claim 12, wherein the first heating vessel further comprises: One or more recesses formed in the bottom of the first heating vessel, and a corresponding number of rods seated in each of the one or more recesses, the rods being composed of graphite.

16. A method for purifying graphite particles, comprising: providing a container formed at least in part from graphite; placing graphite particles into the container; inductively heating at least a portion of the container, thereby heating the graphite particles in physical contact with the container; as well as The container and the graphite particles are cooled.

17. The method of claim 16, further comprising the step of continuously feeding graphite particles into the container.

18. The method according to claim 16, wherein the step of loading the graphite particles into the container is performed by loading the graphite particles into the container in batches.

19. The method of claim 16, wherein the cooling step further comprises selectively activating a cooling jacket surrounding the vessel.

20. The method of claim 16, wherein the temperature of the graphite particles is controlled by measuring the temperature of the graphite particles during purification of the graphite particles.

Images