Rare earth metal smelting

Abstract

An electrolytic reduction smelting furnace system for producing rare earth metal, the system comprising: a) a furnace for smelting, the furnace comprising: i) a furnace cell for holding molten salt; and ii) anodes and a cathode for passing electric current; and b) an automated system for monitoring and controlling the furnace, the automated system comprising: i) a monitoring system comprising: a camera for monitoring operation of the furnace; a temperature sensor for monitoring operation of the furnace; optionally a conductivity sensor for monitoring oxide concentration in electrolyte; and optionally a spectral sensor for sensing spectral data during operation of the furnace; and ii) a control system, for controlling the furnace, based on measurement from the monitoring system, the control system comprising: an electrical control system for controlling electrical power to the furnace; and a feed rate control system for controlling feed rate, feed schedule, or both.

Description

RARE EARTH METAL SMELTINGCROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 713,738 filed October 30, 2024, which is hereby incorporated by reference.FIELD

[0002] The disclosure relates generally to the field of smelting rare earth metals from rare earth oxides.BACKGROUND

[0003] This section is intended to introduce various aspects of the art, which may be associated with the present disclosure. This discussion is believed to assist in providing a framework to facilitate a better understanding of particular aspects of the present invention. Accordingly, it should be understood that this section should be read in this light, and not necessarily as admissions of prior art.

[0004] Rare Earth is the name of a group of 17 individual elements, including yttrium (Y) and scandium (Sc), as well as 15 lanthanide elements: lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). They may not be particularly rare in the earth’s crust in comparison to base metals such as copper, nickel, lead, zinc, etc. However, rare earth elements (REEs) are often found together as a group in minerals such as bastnaesite, monazite, apatite, etc. To separate the rare earth minerals from the rock and divide the rare earth elements from each other may be difficult. Rare earth separation technology may play an important role in the rare earth mining and recovery industry.

[0005] Rare earth elements may be important, as they have wide applications in many high technology areas. According to the Department of Energy of the United States, neodymium (Nd), dysprosium (Dy), europium (Eu), and terbium (Tb) are classified as critical based on their importance and low supplies. Rare earth elements may have distinctive electrical, metallurgical, catalytic, nuclear, magnetic, or luminescent properties and may be important for many advanced technologies, including consumer electronics, computers and networks, communications, clean energy, advanced transportation, health care, environmental mitigation, national defense, etc. Usage ranges from daily use (e.g.,lighter flints, glass polishing mediums, car alternators) to high-end technology (lasers, magnets, batteries, fibre-optic telecommunication cables).

[0006] Rare earth elements may be mined from the earth’s crust as ore deposits and may be recovered through stages of physical and chemical separation processes. The physical separation process typically includes crushing, grinding, gravity separation, magnetic separation, electrostatic separation, sensor-based sorting such as X-ray sorting, and / or flotation. The chemical separation process may include calcination, roasting, leaching, fractional precipitation, ion exchange, and solvent extraction. The physical and chemical processes may be drastically different due to the unique characteristics of each ore deposit. Rare earth orebodies may have complicated mineralogy that may make the recovery and separation processes complicated, expensive, or environmentally challenging. Ores may comprise monazite, bastnaesite, or a mixture of monazite and bastnaesite.

[0007] Rare earth elements may also be recovered from recycling the end of life materials like permanent magnets that includes high concentrations of Nd, Pr, Dy and Tb oxides.

[0008] Rare earth elements are an important component of modern technology and are used in the manufacturing of, for instance, electric vehicles and wind turbines. There may be many processing steps involved in the production of rare earths including mining, concentration, hydrometallurgy, separation, metal smelting, and magnet manufacturing. Each processing step may require various unit operations and mechanical equipment to produce the product. Rare earth smelting is a midstream operation where the rare earth oxides are converted into rare earth metals.SUMMARY

[0009] It is an object of the present disclosure to obviate or mitigate one of more challenges with metal smelting electrolysis.

[0010] According to an aspect of the present disclosure, an electrolytic reduction smelting furnace system for producing rare earth metal is provided, the system comprising: a) a furnace for smelting, the furnace comprising: i) a furnace cell for holding molten salt; and ii) anodes and a cathode for passing electric current; and b) an automated system for monitoring and controlling the furnace, the automated system comprising: i) a monitoring system comprising: a visual light camera for monitoring operation of the furnace; and a temperature sensor for monitoring operation of the furnace; and ii) a control system, for controlling the furnace, based on measurement from the monitoring system, the controlsystem comprising: an electrical control system for controlling electrical power to the furnace; and a feed rate control system for controlling feed rate, feed schedule, or both.

[0011] The monitoring system further may comprise a conductivity sensor for monitoring oxide concentration. The monitoring system may further comprise a spectral sensor for sensing spectral data during operation of the furnace. The monitoring system may further comprise a thermal spectrum camera for mapping the surface temperatures. The monitoring system may comprise a cathode load sensor for sensing electrical load on a cathode positioning device , and wherein the control system comprises the cathode positioning device for positioning and moving the cathode within the furnace cell, based on measurement from the cathode load sensor or feedback from motors that drive the cathode positioning system.

[0012] The system may further comprise an agitator for agitating the molten salt, wherein the monitoring system comprises an agitator load sensor for sensing load on the agitator. The control system may control the agitator, based on measurement from one or more of the agitator load sensor, feedback from motors that drive the agitator system, the cathode load sensor or motor feedback, the visual light camera, the thermal spectrum camera or the temperature sensor.

[0013] The system may further comprise an extraction system for extracting the rare earth metal from the furnace and controlled by the control system, wherein the monitoring system comprises an extraction system load sensor for sensing load on the extraction system, and wherein the control system controls the extraction system, based on measurement from the extraction system load sensor and / or the information from the visual light camera or the thermal spectrum camera.

[0014] The system may further comprise an anode retraction system for moving, replacing, and positioning at least one of the anodes, wherein the monitoring system comprises an anode retraction system load sensor for sensing load on the anode retraction system, and wherein the control system controls the anode retraction system, based on measurement from the anode retraction system load sensor.

[0015] The system may further comprise a sample collection system for collecting a sample from the furnace and controlled by the control system, wherein the monitoring system comprises a sample collection load sensor for sensing load on the sample collection system, and wherein the control system controls the sample collection system, based on measurement from the sample collection load sensor. The automated system may comprise a notification system for providing a notification when the monitoring system measures a parameter outside of a set range.

[0016] The system may further comprise an automated feeding system having one or more load cell scales for determining the amount and rate at which one or more products are added to the furnace cell. The automated feeding system may be configured to pre-mix two or more of the products for providing to the furnace cell.

[0017] The furnace cell may comprise a precast insulation shell having castable refractory cement rings. The castable refractory cement rings may comprise a tongue and groove system for reducing drafts. The insulation may also incorporate a layer of magnesium oxide powder.

[0018] The furnace cell may further comprise instrumentation mounting points for one or more of the agitator load sensor, the visual light camera, the thermal spectrum camera, conductivity sensor, or the temperature sensor.

[0019] The system may further comprise a multifunction mast configured to attach to one or more of the furnace cell, the monitoring system, or the control system. The multifunction mast may further comprise a cathode suspension mechanism for positioning the cathode and performing cathode load sensing. The multifunction mast may further comprise a mixer mechanism for stirring furnace reagents and load sensing.

[0020] The system may further comprise a scrubber system controllable by the control system to reposition an intake of the scrubber system intake. The system may further comprise a robotic arm controllable by the control system to perform one or more of removing material and replacing anodes.

[0021] According to another aspect of the present disclosure, a method of operating an electrolytic reduction smelting furnace system for producing rare earth metal is provided, the method comprising: a) monitoring operation of the furnace, including visual monitoring, temperature monitoring, and spectral monitoring; and b) controlling operation of the furnace, including controlling electrical power to the furnace and controlling feed rate, feed schedule, or both, based on measurement from the monitoring. The method may further comprise interpreting, using artificial intelligence , current and historical monitoring data with analytical results for a molten bath and produced metal to produce control inputs; and wherein controlling operation of the furnace is based on the control inputs.

[0022] According to another aspect of the present disclosure, a process for producing rare earth metal is provided, the process comprising: a) dissolving rare earth oxides in corresponding fluorides; b) producing rare earth metal using electrolytic reduction; c) monitoring the electrolytic reduction, including visual monitoring, temperature monitoring, and spectral monitoring; d) controlling the electrolytic reduction, including controlling electrical power to the electrolytic reduction and controlling feed rate, feedschedule, or both, based on measurement form the monitoring; and d) collecting the rare earth metal.

[0023] Other aspects and features of the present disclosure will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments in conjunction with the accompanying figures.DETAILED DESCRIPTION

[0024] For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the features illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Any alterations and further modifications, and any further applications of the principles of the disclosure as described herein are contemplated as would normally occur to one skilled in the art to which the disclosure relates. It will be apparent to those skilled in the relevant art that some features that are not relevant to the present disclosure may not be shown in the drawings for the sake of clarity.

[0025] At the outset, for ease of reference, certain terms used in this application and their meaning as used in this context are set forth below. To the extent a term used herein is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in at least one printed publication or issued patent. Further, the present processes are not limited by the usage of the terms shown below, as all equivalents, synonyms, new developments and terms or processes that serve the same or a similar purpose are considered to be within the scope of the present disclosure.

[0026] Throughout this disclosure, where a range is used, any number between or inclusive of the range is implied.

[0027] The present disclosure provides an electrolytic reduction furnace for producing rare earth metal. An automated system for monitoring and controlling the furnace may be provided.

[0028] Electrolysis is an important process used in metal smelting. Electrolysis cells may be used for this purpose, in which the rare earth oxides are reacted with their corresponding rare earth fluorides to form a molten pool. The furnace may be equipped with anodes, for instance made of graphite, and a cathode, for instance made of tungsten, the cathode and anodes being suspended in the furnace. An electric current is passed through the anode and cathode elements and the molten fluoride salt causing a reactionby which the rare earth ions are liberated from the oxides and migrate towards the cathode where they are reduced to their pure metallic form. The molten pool of rare earth metal may be accumulated in a collection bowl at the bottom of the furnace, usually made of titanium, molybdenum or tungsten. The metal may then be extracted out of the collection bowl after certain intervals when sufficient pure molten metal has collected. This is known as scooping or extraction.

[0029] The electrolysis process occurs at very high temperature, often above 1000°C, and precise temperature control is important to achieve efficient metal reduction and purity.

[0030] Rare earth metals are highly reactive, especially in presence of oxygen, so the process of extraction sampling and storage may be carefully designed and controlled to mitigate product contamination by oxidation.

[0031] The rare earth molten metal is prone to contain impurities which can be included during the electrolysis process. Low concentrations of impurities like carbon, oxygen or other metals may cause the rare earth metal product purity to fall below commercial grade specifications. The potential source of carbon in the produced metal may be generated from the materials in the furnace, such as graphite anodes and graphite crucible, and reaction between the graphite and oxygen present in the rare earth oxides. The oxygen contamination may come from incomplete reaction or during the mixing or pouring process when the metals are extracted or scooped out from the collection bowl. Metal contamination can come from metal instruments used to mix the heated pool or from removing the produced metal, such as when taking samples.

[0032] The rare earth electrolysis reduction process uses rare earth fluorides and lithium fluoride. When heated by the conduction of the electric current, the fluorides form a molten salt electrolyte which facilitates the rare earth metal reaction. The REE fluoride may be consumed by the reaction and minimizing the rate of consumption may be an important factor in maintaining the economic viability of the process. Fluoride consumption can become excessive if the process temperature (governed by electric voltage and current) is not uniformly maintained. Temperature is affected periodically by the scooping of the metal and factors such as changing graphite anodes. Some of the electrolyte may be removed from the furnace during metal scooping / extraction. Some of this removed electrolyte may be recycled in small amounts in a manner that has minimal effects on process temperature and quality of the produced metals.

[0033] Rare earth smelting process economics also depends on the conversion efficiency (recovery) of the oxides to metals and the purity of the produced metals. Thesetwo parameters are highly dependent on precise process control that includes stable and uniform temperatures across the four operation phases of the furnace. During startup, it is desirable to progress quickly to steady state operation where the metals are produced so automation during startup can minimize non-productive time and consumption of reagents and production of off-spec product. In the second operation phase, steady state, is where the majority of the good product is produced so the automation system can optimize inputs to achieve maximum production at the desired purity. Inputs include the feed of rare earth oxides and fluorides, electrical current and voltage, mixing parameters including speed, duration and frequency. In the third operation phase, extraction, the removal of the metal and refilling with feed materials, introduces variations in temperature as the extraction tools are cooler than the molten material and acts as a heat sink, lowering the pool temperature. The feed material which replaces the scooped metal is also cooler than the pool and if added in the incorrect rate and time can cause formation of slag and out of specification products. In the fourth phase, the anodes are replaced causing similar reduction of temperatures with the same problems. The control system, by regulating the reaction and process parameters, extends the life of the anodes which are normally consumed during the reaction. The anode consumption is increased during the period of time between extraction and refilling to the optimal pool level due to increased exposure to oxygen in the atmosphere and the fluoride consumption. Note that the graphite anodes are consumed during the reaction and need to be replaced after a certain time, if the rate of consumption is higher the risk of increased concentration of carbon in the product increases. With every replacement the temperature of the furnace may drop significantly impacting the recovery and the purity of the smelted metal.

[0034] Some known metal smelting technologies do not include a high degree of automation. A control system and components of the process may be introduced with automation including feeding system, mixing, sampling, extraction, and anode replacement. Rare earth metal smelting is a complex process with costly inputs and consumables so an integrated process control with a high level of automation may be beneficial to yield high recovery and purity with appropriate cost. Described herein is a process using automation, including for example artificial intelligence, with associated potential benefits including improved recovery, purity, capacity, and operating costs.

[0035] Metals smelting using electrolytic reduction furnaces usually requires a lot of intense manual labor to operate, feed, mix and extract the metals. This work may be hazardous and uncomfortable for workers since the furnace operates above 900°C. Workers need to wear bulky, heavily insulated personal protective equipment (PPE) toavoid severe burns and injuries. Workers feeding materials into the furnace can be exposed to high temperatures and hazards which can arise including steam explosions resulting from feeding material contaminated by water being introduced into the furnace. If the feed has moisture in it, the water can turn into steam when introduced to the furnace creating a dangerous explosion comprising molten metals and lithium salts or other materials. During smelting, emissions from the furnace can include hazardous gases or particulates requiring that the operators wear respirators or supplied air breathing apparatus which can also be cumbersome and uncomfortable for the operators. The metals smelting furnace control system and mechanisms described herein may allow the operator to be positioned away from the furnace to a large extent except where direct manual intervention is required. This system may improve the operator’s safety while improving the quality and purity of the produced metal products. Having a consistent feed rate and electronic controls may allow for more consistent and moderated feed rates and temperature which, when dysregulated, can cause low quality reaction and metals conversion. The monitoring and data logging may provide a method of ensuring and proving the quality of the materials and process. Another potential benefit may be that a worker operating automated furnaces can oversee more furnaces due to the reduced manual labor requirements. The operator’s role may change from that of manual furnace operation (controlling electrical power, feeding, stirring, extracting, changing anodes, replacing electrolytic fluoride salts) to one of overseeing and monitoring the electronic automation system and managing issues. In this way, labor costs may be reduced.

[0036] The present disclosure provides an electrolysis furnace with automation and control system.

[0037] The furnace and one or more multifunction masts may have a control system which can operate the electrical power supply to the furnace which drives the electrolytic reduction reaction and can control the supplied electrical power to achieve the desired furnace performance. The multifunction mast may have attached equipment which allows the control system to operate various functions of the furnace smelting processes. The multifunction mast may have an attached mechanism to precisely position the cathode and control the motion of cathode, and include cathode load sensing. The furnace and multifunction mast may have a cathode suspension mechanism which integrates both electrical conductivity and mechanical connection of the cathode to the cathode positioning and load sensing elements. The furnace and multifunction mast may have an attached mixer mechanism with position and motion control and load sensing that is able to providestirring for the furnace reagents and detect the formation of sludge or undissolved feed or reagents within the furnace.

[0038] The furnace may have integrated electrical insulation and instrumentation.

[0039] The mixer attached to the multifunction mast may have a drive mechanism which also includes electrical and thermal isolation. The mixer drive may be mounted such that it is at the same electrical potential as the mast while the mixer arm which directly contacts and is submerged in the molten fluid within the furnace is at a different electrical potential. To prevent or mitigate the electric power shorting out through the drive mechanism, the drive may include a unique electrical isolation, for instance made up of ceramic disk and ceramic rods or “fingers”. The ceramic disk and rods may withstand the heat radiated from the furnace and conducted through the mixer shaft as well as the mechanical forces which suspend and impart rotational movement to the mixer from the mixer drive. The isolator disk and rods may create a thermal break as well as an electrical circuit break. This ceramic disk design may be both a mechanical transmitter and electrical isolator while being a thermal insulation and offering thermal resistance into the mechanism.

[0040] The furnace and multifunction mast may have both the cathode positioner and mixing attachments designed to withstand furnace operating temperatures over 900°C and the attachment where the mixing spindle is attached may be positioned outside the highest temperature zone. The mixing mechanism may offer two unique motions independent of each other.

[0041] The motors of the mixing rod and rotational arm may be used by the control system to calculate the viscosity of the molten salt and indicate the extent of reduction process and estimate of the rare earth metal in the collection pot. The viscosity of the molten salt and rare earth pool in the furnace is a function of the temperature and the concentration of the various constituents within the furnace and by measuring the temperature and using the known added quantities of the products within the furnace, an Al algorithm or other automation, can estimate the conversion rate and reaction progress within the furnace by using the feedback of force required to stir and move the stirring element through the molten pool.

[0042] The furnace may have a mechanism which may be mounted to the multifunction mast and operated by the control system which can extract the produced metals from the furnace.

[0043] The furnace and multifunction mast may have a sample collection device which can get samples of the produced metals or electrolyte bath.

[0044] The furnace and multifunction mast may have an automated feeder controlled by the control system which dispenses the rare earth feed material and / or the rare earth fluorides and reagents which make up the electrolytic bath precisely to control furnace performance. The automated feeding system may be configured to feed multiple products into the furnace. For example, in the case of NdPr metal production, products added to the smelting furnace by the automated feeding system can include lithium fluoride, Nd fluoride, Pr fluoride, Nd oxide, and Pr oxides. The fluorides may be pre-mixed in a desired ratio. The automated feeder system can meter or provide a mixed NdPr oxide and a blended fluoride product. The feeder may meter or provide one or more products in different pre-mixed blended ratios or as individual constituents, or, for example, as partially blended components. The metered provision of individual, partially blended, or blended products may be controlled by the control system. In some embodiments, the provision of the products may be controlled by the operator.

[0045] The automated feeder system may control the rate at which oxides and reagents are fed into the furnace and may use an integrated scale or balance to accurately measure the amounts added.

[0046] The automated feeder system may have a feed hopper included in the weighed mass on the balance with a separate secondary hopper which is larger than the feed hopper and is used to replenish the feed hopper with feed material. This may reduce operator interaction since the feed system can be reloaded at longer intervals without running out of material. A secondary hopper may be mounted substantially above the feed hopper so that it can reload the feed hopper by operation of a small conveyor or valve.

[0047] The furnace and multifunction mast may have a mechanism controlled by the control system which can remove and replace spent anodes which are regularly consumed during the smelting processes.

[0048] An electrolytic reduction smelting furnace is described with automation and control system for (rare earth) metals smelting with associated equipment and instrumentation. The furnace may have reduced manual user labor and inputs. The system may include control and automation of an electrolytic reduction smelting furnace including components which are operated by the control system. The smelter control system may control the electric power (voltage or current) which drives the smelting reaction and uses instrumentation including temperature sensors and an electronic camera system to monitor the smelting reaction and furnace operation. The control system may be programmed to maintain a desired feed rate and feed rate schedule by which the metals feed (oxides) and reagent electrolyte fluoride salts are introduced into the smeltingfurnace. Electro-mechanical control of the cathode positioning as well as a mechanical agitator (stirring) or mixer may be operated by the control system. Retraction and reposition of the same may be controlled by the system to automate functions required for allowing extraction of the produced metals from the furnace cell. The automation control system may operate an extraction system for removal of the metals produced and collect samples of the metals or electrolyte. The control system and automation may operate a mechanism for removal and replacement of anodes when they are consumed in the smelting process.

[0049] Cell

[0050] Improved insulation, precast. The furnace cell may have a new precast insulation shell made of castable refractory cement rings to improve efficiency by reducing power consumption as a result of reduced heat loss and improved operating function by providing more stable temperature profile. Rings may have a tongue and groove system to minimize drafts through the seams. The insulation is designed to allow installation with minimal operator effort and to fit accurately at the geometric center of the cell. Normally, cell insulation may be installed in multiple small pieces which are less accurate and require more manual labor. The precast insulation may provide superior insulation by reducing or completely eliminating seams which may create inefficiencies and uneven temperature profiles within the cell during operations. The insulation provides valuable control over energy loss and temperature stabilization but cannot be too efficient or provide too high a degree of insulation. The reduction process is exothermic and some energy must be allowed to dissipate in order to keep the temperature of the electrolytic solution from getting too high. Insulation which is too thick or efficient will not allow sufficient energy to dissipate. Excess temperature results in higher consumption of the anodes and electrolyte solution. At the same time, insulation which is not sufficiently efficient will make the furnace startup more difficult and may lead to the formation of cold zones at the bottom of the furnace.

[0051] Integrated temperature sensor mounting. The cell design may incorporate instrumentation mounting points for temperature sensors. Multipoint temperature data is one important metric that may be used by the control system to maintain desired process conditions and steady state reaction, with a goal of conversion efficiency and appropriate quality of the produced metal. Data from multiple thermocouples installed in the different layers of insulation can be used to extrapolate the temperature inside of the furnace.

[0052] A precast crucible may be made out of high quality graphite, and have a pre-cast slot for metal collection. The bottom of the crucible may have a slope to enhance metal drainage to the centrally located metal collection point. Concentric location mayenhance the uniformity of the reaction and help eliminate hot or cold spots in the reaction. Uniform temperature profile throughout the cell may enhance the quality by eliminating or mitigating cold spots or hot spots which can result in uneven reaction in quality of metals produced.

[0053] Insulated top plate. The design may introduce an upper plate which is separated from the cell body by thermal and electrical insulation. Thermal insulation may reduce heat lost by the cell and reduce power consumption, increasing the efficiency of operation. The top plate may operate at a lower temperature making it safer and more comfortable for operators working in proximity to the upper part of the furnace. The top plate may also have a cooling system using a circulating coolant. The lower temperature may also result in more efficient conduction of electrical power which transfers more energy to the anode-electrolyte-cathode circuit. The top plate is a link in the power conduction circuit connecting the main power buss from the power supply to the graphite anodes and is designed to provide a high quality connection to the brackets which attach the anodes to the top plate. The top plate features integrated mounting points for the clamping mechanism which accurately locates and retains the anode mounting brackets.

[0054] Precision electrical connection point. The furnace cell may be designed for highly efficient electrical connections unlike traditional designs. The machined surfaces may mate directly to both the power supply bus and the anode retainer brackets. The improved electrical connection may provide more stable power to drive the smelting reaction and may improve efficiency through reduced power loss as heat production.

[0055] Anode Retainers. The cell may feature anode retainer brackets which may serve several functions. The retainers may locate the anodes accurately. Accurate spacing and location ensures that all the anodes conduct electricity evenly promoting a uniform conversion / reduction reaction throughout the cell to increase throughput product purity and reduce energy consumption and impurities. The anode retainers may be constructed of a conductive, durable metal alloy with integrated lifting points which facilitate changing out of spent anodes and precisely locating the replacement. The anode retainer may have surfaces / connection points which may allow robotic manipulation and movement when the anodes need to be changed. The conductive material may promote efficient electrical conduction to ensure that the anodes serve the intended function of delivering electrical current and power to drive the reaction. The anode retainers may be designed to promote good electrical connections between the retainer and the graphite anodes and the retainer to top plate connection. The anode retainers may also have integrated lifting points allowing a hoist or crane to be attached when operators need to lift them without the use ofthe robotic positioners. Anode retainers may have slots for anode covers that prevent gas circulation behind the anodes, reducing oxidation and consumption of the exposed anode surface.

[0056] Anodes. The anodes may be designed to fit precisely within the cell providing optimal spacing between the external crucible and the cathode, which may be at the geometric center of the cell. The uniform and precise location may ensure that an even distance is maintained between the anodes and the cathode which eliminates or mitigates hot spots and cold spots as a result of uneven electrical conduction throughout the electrolyte. Anodes may have grooves to increase the surface area and facilitate the removal of CO and CO2 gas produced during the reaction.

[0057] Insulated covers which facilitate feeding. The new cell design may include insulation covers which can close up the top of the furnace. This is an area which is normally left open but the present furnace design may include unique insulation which is precast as a precise fit to both the cathode and top plate. The insulation may increase operating efficiency by reducing radiative and convective heat loss from the upper surface of the molten pool of electrolyte. The furnace may maintain a more even temperature gradient throughout the electrolyte and produce less slag as well as consuming less power. An added benefit may be that the insulation reduces exposure of the graphite anodes to direct atmospheric and can increase the lifespan of the anodes by reducing oxidation at the upper portion which is exposed to air. Extending the life of the anodes may reduce operating costs and also reduce contamination of the final metal produced by lowering the carbon content in the electrolyte and produced metal. The insulation covers may be designed with integrated feeding port so that rare earth oxides and fluorides can be added as per the control systems desired feeding rate without disturbing or moving the insulation. The insulation may be removed temporarily when changing anodes or extracting molten metals.

[0058] Control system. The control system may use several components to monitor the smelting process, process the data and provide output controls to operate the various parts of the system. The central components may include the processor, sensors, robotic manipulators, PLC, the HMI or human interface and the main housing. The interface may comprise a display screen and multiple user inputs switches and controls. The control system may include the following:

[0059] Electrical power. The control system may control the electric power rectifier that drives the electrolytic reaction. The control system may have the ability to control DC voltage and / or DC current output from the rectifier. This may directly affect boththe chemical reaction and temperature of the molten electrolyte and is the main input to control the temperature and rate of reaction. Consistent monitoring and adjustment of the power may yield stable conditions which may enhance reaction efficiency and the rare earth metals recovery and purity. The control system may continuously adjust the electrical power to achieve the target temperature. The control system may coordinate all the functions of this system with use of the artificial intelligence programming so that the power output profile may be modified to correlate with increases or decreases in feed rate and also other activities such as stirring or extraction where the cathode is moved in relation to the anodes to promote longevity of the anodes and avoid or mitigate creating hotspots or cold spots within the cell as a result of over or underpowering the electrical power supply during these other operations. After extraction when feed rates may be increased to replace both the rare earth metals and the electrolyte lost during extraction the control system may modify the power output to reduce recovery times to achieve steady state temperature and reactions. The Al algorithm may use data from the temperature sensors, conductivity sensors, thermal camera spectra, visual light camera images and / or other sensors to determine an appropriate or optimal power supply rate, timing curves, and feeding rate during all functions of the cell. If the power output remains constant during a time where the cathode is moved close to an anode, as such as would happen during extraction or stirring, this may cause premature failure or increased erosion of the adjacent anode as well as decrease quality through the inclusion of additional carbon which is lost from the anode when it erodes. System control may increase quality of the produced metal.

[0060] Camera monitoring temperature and level. The control system may use a feedback signal from a thermal and / or visual light cameras to determine the temperature of the molten electrolyte salt, which is an analogue of the pool mean temperature. The thermal camera may detect hot spots or cold spots within the molten pool and using the control system to adjust the position of the cathode can move the cathode towards a cold spot or away from a hot spot affecting the electrical resistance between the cathode and the adjacent anode this will change the amount of electrical power conducted through the electrolyte in that region and can be used to heat up cold spots or cool down hot spots. The goal of the control system may be to optimize the temperature profile in the pool to achieve a very even distribution of temperature throughout the entire reaction zone. A consistent temperature profile may result in maximizing throughput and productivity and minimizing the production of slag or low quality product. With the use of Al in the control system, the camera may also provide data which the control system can interpret as the fill level of the furnace to avoid over or underfilling, controlling both the feed rate and extractionrate to maintain the target fill level. Overfilling can reduce the efficiency of the reaction, introduce contamination and cause spillage whereas underfilling can waste capacity and production capability while increasing the consumption of the graphite anodes through excessive oxidation when they are not sufficiently submerged within the pool of molten fluoride salts.

[0061] Spectral monitoring. A dedicated spectrophotometer sensor may collect the spectral data from the molten pool and may estimate the composition including the percentage of the dissolved oxides in the electrolyte. This data may be used by the control system to adjust the feeding rates and the electric power fed into the system.

[0062] Conductivity and oxygen sensors. Conductivity sensors comprised of materials such as titanium, molybdenum, tungsten, platinum or other high temperature materials may be installed in the furnace to continuously monitor the concentration of oxides in the electrolyte. The data may be used by the control system to optimize the feeding rate.

[0063] Mast Precision positioning. The multifunction mast is the core component on which the cathode positioner, the stirring mechanism, the upper jib crane, and other components may be located and may provide a precise mounting point and positioning of these components which may be important to the operation of the control system and cell function. The mast may be constructed of heavy gauge steel tubing with precision machined mounting points for all of the key components. This may include track systems and brakes which may provide precise height adjustment and safety for operators

[0064] Grounding. The multifunction mast may contain insulated mechanical drives which isolate the tools and instruments mounted on the mast from the mean electrical power circuit which is used to drive the electrolytic reduction reaction.

[0065] Cable Management. Electrical and control cabling may provide connections and communication between the various components of the system. A cable management system may be included in the multifunction mast design which provides a safe and controlled location for power conduction cables which are used to drive the stirring function the cathode positioning operation as well as the jib crane power and other components. Cabling for instrumentation may include temperature sensors, position sensors, load sensing components, and other parts of the control system, which may be managed within the multifunction mast cable management system. The cable management system should maintain safety for operators and thermal insulation and protection for all of the cables and wires.

[0066] Jib crane mount. An integrated mounting point for a jib crane may be included in the multifunction mast design. The jib crane mounting point may be located at any suitable or convenient location on the mast, for instance the mounting point may be at the top of the mast providing coverage of the jib crane over all of the useful areas of the top plate and furnace area. The purpose of the crane may be to assist operators with maintenance and operations due to many of the components being too heavy for operators to safely manipulate.

[0067] Geometric location to furnace. An important element of the mast design is its convenient and precise location with respect to the geometric center of the cell. The control system may operate the position of the stirring system and the cathode positioner optimal performance may be achieved when the mast is located in precise relationship to the cell so that the full functions of the positioning systems are achieved. A positioning jig or location system may be used to ensure that the mast position and cell body have a precise relationship. This may allow a modular design where individual cells and individual masts can be switched around as needed to facilitate maintenance and installation without adverse effects on system performance. The mast may be positioned so that it is vertical or plumb in relation to the cell so that the longitudinal center axis of the mast is parallel to the center vertical axis of the cell. This ensures that the positioning of the cathode and stirring system maintains a precise relationship with the cell at all times.

[0068] Mixer. The embodiments of the present disclosure referring to the mixer may similarly be configured with an agitator, stirrer, or other suitable apparatus.

[0069] Electric and thermal isolation. To ensure proper function and longevity of the mixer components, they should be electrically and thermally insulated from the cell's power system. This may be done using a design with multiple ceramic pins and a ceramic top plate. The mixer drive may have a connection which conducts mechanical power while providing thermal and electrical insulation. This mechanism may include ceramic disks and rods combined with metal components.

[0070] Positioning. The mixer rod may be operable about a vertical axis concentric with the center of the cylindrical shaped furnace body, with a user defined speed and the mixing attachment rotates such that the mixer rod can rotate over a different array in this instance approximately a 270 degree angle within the furnace. The circular motion of the whole attachment may be moved at variable speeds. In addition to the rotation about the furnace center axis, the radius or distance from the center of the furnace may be adjusted or in some cases actuated via the control system to affect a larger area within the furnace, including the zone under the graphite anodes where stirring is often more difficultdue to reduced accessibility. The mixer rod may be made of a metal alloy which is capable to withstand the furnace temperatures of over 900°C and includes a mean vertical shaft with one or more mixing elements located at or near the bottom of the shaft. The mixer elements and the shaft may be constructed so that they are strong enough to encounter slag or other impurities which may precipitate at the bottom of the cell and the purpose of this stirring element is to help detect and break up any precipitated solids within the cell. The mixer may introduce mechanical agitation which may be an important feature during startup to facilitate the establishment of a molten pool of electrolyte, for dissolving sludge and for enhancing the chemical reaction in cases where the reaction has slowed. This may occur after extraction when the level and temperature of the contents of the cell are reduced and when additional electrolyte or feed material needs to be introduced at a higher rate to get the cell back to steady state operation. The mechanical mixer may enhance safety by eliminating or mitigating the need for operators to manually agitate the contents of the cell. Manual mixing may be dangerous because it puts the operator in close proximity to the extremely hot furnace and its contents. The mixing rod used by operators during manual mixing can get very hot and can only be used for a short time before it becomes too hot for the operator to handle. An automated electromechanical mixer may allow more thorough aggressive and longer duration mixing than can be achieved by an operator on their own. This may help the mixing be more effective and when combined with the artificial intelligence in the control system can be precisely applied exactly when needed to ensure that the throughput is maximized and quality is optimized. The mixer components may be mounted on a horizontal arm which is attached to the vertical multifunction mast. A mechanical drive system operated by electric motors may be controlled by the control system to move the arm vertically up and down or horizontally in relation to the mast and furnace cell. This horizontal mixer arm may have a feature that allows it to be coupled rigidly to the drive system during normal operations but moved out of the way for maintenance by the operators with a very simple and fast mechanism. The operator can uncouple a latch releasing a portion of the horizontal mixer arm to swing horizontally out of the way to facilitate maintenance or improve ergonomic access to the cell for any purpose. Once the maintenance operation has concluded, the horizontal arm can be repositioned and coupled without any loss of accuracy in positioning for requirement for recalibration. These operations may be automated by an addition of a servo motor and latch mechanism. The horizontal mixer arm may be mounted to a base which may be attached to the multifunction mast. This space uses brakes which prevent the arm from sliding down the mast and ensure that the precise positioning is maintained.

[0071] Load sensing. The mixer drive system may incorporate a load sensing function that allows the control system to determine if the mixer has encountered an obstruction such as slag which may precipitate at the bottom of the cell. With load sensing, the control system may detect and avoid damaging the mixer or the cell by stopping the movement of the mixer before bending the mixer shaft. This is an important feature of the mixer control system since it avoids or mitigates costly repairs in down time. It may also provide useful feedback to the control system and operators that there is an obstruction or problem within the cell that would otherwise be undetectable. Typically, the only other way that the problem could be discovered is for the operators to manually insert a mixing rod and operate it themselves to discover problems. The load sensing function may operate by monitoring the electrical load of the electric motors which actuate the mixer movement and if the current draw increases suddenly this would be an indication that mixer has encountered an obstruction.

[0072] Cathode positioner

[0073] Load sensing. The load sensing function of the cathode positioner may operate similarly to the mixer arm load sensing. The cathode positioner may be made-up of a base unit which attaches to the multifunction mast and a horizontal arm attached to the base, which connects to the cathode. The cathode mounting arm may be operated by an electromechanical drive system and the load sensing function may be achieved by monitoring the electrical load on these electric drives. A sudden increase in electric motor load may indicate that the cathode has encountered an obstruction and the control system can't use this signal to indicate when it needs to stop and avoid damaging the cathode or the anodes or any other component. The load sensing may also provide a useful function during startup of the furnace. At startup, a shunt is typically installed to provide an electrical connection directly between the cathode and one of the anodes. The electrical power passes through the shunt causing it to heat up and provides the initial heat source to begin melting the fluoride electrolytes and to facilitate the reduction reaction. The heat generated by the shunt acting as a resistor also starts to heat up the furnace and is critical to the startup process of the cell. The main challenge is that the shunt is made of graphite and is slowly consumed by oxidation during startup process. As the shunt is consumed it gets progressively smaller and will fall out of position and lose the electrical connection if it gets too small. The control system for the cathode positioner can monitor the force required to hold the shunt in position between the cathode and anode and slowly adjust the position of the cathode to maintain sufficient pressure on the shunt to hold it in position during the startup process. Without load sensing, the operator would have no means to judge thecompressive force between the cathode and the anode and would risk damaging one or both of the components when trying to clamp the shunt by moving the cathode closer to the anode. The load sensing function may allow very precise control over the pressure and may avoid or mitigate damaging these critical components and may allow the operator to focus on other parts of the startup process including optimizing feed rate of the fluorides and rare earth oxides into the furnace instead of trying to monitor the position and compression on the shunt.

[0074] Precision location of cathode. Controlling the location and position of the cathode is important for several reasons. The control system may observe the temperature at the surface of the pool and detect cooler areas which would benefit from additional electrical power to ensure a homogenous reaction throughout the cell. The positioner may move the cathode closer to the anodes in a location corresponding to the colder region of the pool, which will increase electrical current in that region which will counteract and heat the cold area faster. This can be useful for preventing and reducing the production of slag or fine tuning the cell performance to ensure maximum throughput, energy efficiency and product quality. Conversely, if the control system detects a hot spot which might result from too much localized electrical current flowing in that area, or an overactive reaction in that zone, moving the cathode away from the hotspot will increase electrical resistance between the cathode and the anode closest to the hotspot effectively cooling it by allowing some electrical current to flow through other anodes.

[0075] The cathode may also be moved down deeper in the electrolyte to bring more heat to the bottom of the electrolyte pool and / or increase the surface area of the cathode in contact with the electrolyte, which may decrease the overall resistance of the system and / or allow for the more power to be added. Conversely, the cathode may be moved up to move the cathode further away from the molten metal at the bottom of the furnace, which may reduce the current and the power consumed by the furnace while maintaining the same voltage. This precise cathode positioning is useful for the intended purpose of driving a uniform, homogenous reaction. The ability to precisely move and position the cathode also is helpful for facilitating metals extraction since the cathode can be temporarily moved aside. Similarly, if mechanical stirring is required, the control system can manipulate the cathode and stirring mechanism simultaneously or separately to promote appropriately aggressive stirring and the swept path of the stirring element to attain optimal stirring performance. As the stirring or extraction operation is concluded the control system can quickly restore the cathode to the optimal position again.

[0076] The control system may also control the movement of the cathode and mixer simultaneously to create more separation between them. The mixer shaft material can be subject to erosion due to electrical current and temperature. The erosion can result in a reduced lifespan for the mixer and / or may also contaminate the metals produced. The control system may coordinate the movements of the mixer and cathode simultaneously so that they orbit around the center of the cell but maximize or increase the distance between them and ensure they do not come into direct contact with each other. The electrical current may be reduced around the cathode on the side which is farthest from the anodes, and this zone may be suitable or optimal to operate the mixer.

[0077] Electrical power connection. One of the primary functions of the cathode positioner is conduction of electrical power as a main component in the electric circuit required by the electrolytic smelting process. The cathode may be held securely in a unique fixture known as a “supernut”. This supernut may be used to clamp the cathode securely with both a mechanical grip and a highly efficient electrical power conduction. This design may use a combination of a precision machined outer cylindrical housing and inner clamping cylinder with a combination of internal and external tapered surfaces which are drawn together by an array of fasteners. The precision tapered design of the inner and outer cylinders may provide both the mechanical and electrical elements of the cathode supernut.

[0078] Feeding system. The feeding system may be the electromechanical operated mechanism which provides the flow of rare earth oxides and in some cases the blended electrolyte fluorides into the cell to maintain the level of the molten pool and the effective throughput rate of the cell. The main components of the feeding system may include a hopper or container in which the premixed oxides and fluorides may be placed and a mechanical conveyor which dispenses the oxides from the container into the cell. The oxides fall by gravity from the end of the conveyor into the molten pool where they begin participation in the chemical reaction. The feeding system may include an array of load cells which weigh the product within the container or hopper and provide feedback to the control system so that it can operate the conveyor to provide a determined feed rate into the cell based on user input or the Al control system instructions. The control system may at times vary the rate of the conveyor to increase or decrease the rate at which oxides and fluorides are introduced into the cell depending on the state of the process at any point. At startup, the control system would optimize the feed rate to reduce the overall time from startup to steady state because it is at steady state that the desired product starts to be produced. The control system is coupled with automated extraction of metals or aprogrammed recovery function after manual extraction of the metals and can operate the feed system to optimize the recovery time and return to steady state operation after each extraction event has concluded.

[0079] Weighing. The feeding system may incorporate a load cell scale system to accurately determine the amount and rate at which rare earth oxides and fluorides are added to the cell which make up the feed. The input weight is important for calculating the total throughput and conversion rate between feed and product. Single load cells or an array of load cells or other load sensing instruments could be used. The feed hopper may be mounted to the upper operable surface of the load cell scale system such that the load cells (balance) support the weight of the hopper, feed screw conveyor and feed material held in the hopper.

[0080] Programable rate. The programmable rate of feed input to the furnace cell is a important feature of the control system in order to optimize the maximum throughput of the furnace and to ensure that existent uniform steady state reaction is perpetuated. It is the consistent steady state operation which may yield the highest performance and purity from the furnace and maintaining the steady state operation depends on a consistent and determined feed rate of the feed materials. With Al, the control system can monitor the system instruments and determine when to adjust the feed rate. For example, after extraction of the metals is completed, the control system may increase both the electric power input and the feed rate in order to shorten the duration of time taken to get back to the optimal fill level and chemical reaction steady state.

[0081] Supply hopper. Mounted above the feed hopper may be a secondary hopper, used to replenish the feed hopper. To attain the required degree of accuracy, the feed hopper may be relatively small compared to the mass of the feed materials which are fed into the furnace. The feed hopper may then, under normal operation, empty quickly requiring the feed hopper to be refilled frequently. The secondary hopper may be much larger and may contain a significantly larger quantity of the blended feed material. Mounted above and adjacent to the feed hopper, the secondary hopper may transfer feed to the feed hopper via a mechanical conveyor, for instance a screw conveyor whenever the feed hopper requires replenishment.

[0082] Metals extraction. Metals extraction in rare earth element smelting is one of the most dangerous and hazardous parts of the operation for operator safety. The produced liquid metal is over 900°C in temperature and poses a significant hazard to operators. In addition to the safety risk, the work is very hot and uncomfortable making it difficult for operators when working long hours or during already hot conditions. The moltenmetal may be put into molds for cooling. This operation also requires a high degree of skill from the operators to complete the same movements each time in order to extract the maximal amount of metal with the least amount of fluoride electrolyte salts. The molten metal tends to collect at the bottom of the furnace directly below the cathode and is generally collected in a cast crucible made of molybdenum or similarly high melting point material. Because the crucible is at the bottom of the furnace, it is not visible to the operator and the operator can only access it by extending a long handled scoop from the top of the furnace down to the bottom where it is difficult to maneuver and to avoid getting either a partial scoop of molten electrolyte or slag instead of the desired metal. This skill is hard to master and because of the high financial cost of the operation and raw materials it is very inefficient to waste the extraction effort and over extract fluorides. This contributes in large part to the difficulty in maintaining and reestablishing steady state reaction after extraction occurs. The optimal performance is to extract only pure rare earth metal from the furnace with a minimal amount of molten electrolyte which would then have to be replenished before achieving steady state again.

[0083] Mechanism. The mechanism for automated extraction of the rare earth metal can be operated by the furnace control system and can be mounted either on the multifunction mast or as a standalone robotic or mechanized extraction unit. If mounted on the multifunction mast, the extraction arm can be operated with electromechanical pneumatic hydraulic or similar elements to articulate the mechanical arm and then achieve the desired extraction of metals by scooping the metal from the bottom of the furnace. The control system is able to learn and replicate the optimal scooping technique in order to minimize removal of electrolyte and maximize the amount of metal extracted per scoop. As the metal is removed from the furnace it is important that it cools within an inert environment to prevent the re oxidation of the metal which can occur very quickly. An advantage of the mechanized extraction is that this motion can be done very efficiently and quickly minimizing exposure to the atmosphere above the furnace and getting the molten metal into the mold quickly and with minimal spillage or risk to operators. Alternatively, extraction system can comprise of a siphon, incorporating a tube made of high temperature alloy prefilled with metal that is lowered into the bottom of the crucible containing molten metal. Electromagnetic induction heating can be used to melt the metal in the siphon tube outside of the furnace and initiate the siphon action. Yet another alternative is vacuum extraction, where a reservoir under vacuum may be lowered into the furnace and filled with molten metal.

[0084] Control system. The role of the control system in the automated scooping is to operate the mechanized robotic arm to manipulate the extraction scoop in such a way as to achieve optimal removal of metal with minimal disturbance to steady state or removal of valuable electrolyte. Use of Al in this process to learn and repeat the extraction of the molten metal by scooping may result in a highly efficient process. An integrated control system which also can operate both the cathode positioner and the mechanical stirring system may be able to coordinate between these elements and remove or move them out of the way to achieve the best extraction performance. This may include the momentary change to the electric power being delivered to the furnace to avoid or mitigate damage or overconsumption of the graphite anodes and, in cases where an operator would have to manually make these changes and then accommodate multiple scoops in the same extraction, it would not be practical for the operator to resume normal furnace operation between scoops increasing the overall disturbance in the steady state condition. The automated control system described herein may control all of these elements and make small momentary changes including moving the other components out of the way to facilitate a single scoop and then resuming both the electric power operation and the optimal cathode position while the scoop is being poured out into the mold and do this series of steps in succession for each scoop required thereby minimizing the overall disturbance to the furnace steady state. The automated control system may also determine how much metal to remove at each cycle, which can reduce the amount of electrolyte removed from the furnace and / or improve the quality of the metal. These small improvements when combined into continuous operation of the furnace overtime may yield an increase (for instance a large increase) in overall performance and capacity of the furnace with reduced impurities in the finished metal.

[0085] Mast mounting. If the automated extraction tools are mounted to the multifunction mast with both the cathode positioner and the automated mixing system, all these components can form a robust modular unit with minimal footprint. This may allow for better flexibility in planned layout and design to achieve a more efficient use of the facility, which may reduce operating cost. The multiple components may share a common power supply and connection to a central control system, which is also operating the furnace power supply and feeding system.

[0086] Anode replacement automation. One of the most difficult and hazardous activities for metal smelting operators use periodic replacement of the graphite anodes during live operation of the smelting furnace. Although this has obvious safety hazards, it is a requirement of the necessary continuous operation of the furnace to replace anodesas they are consumed by the chemical reaction in the furnace. The graphite, which makes up the anodes, combines with the oxygen atoms liberated from the electrolytic reduction of the rare earth oxides to form pure rare earth metal and form carbon monoxide or carbon dioxide and effectively burn up the graphite anodes. Under ideal conditions the graphite anodes will survive for periods of 10, 12 or up to 80 hours or more depending on the overall conditions and chemical reactions occurring in the furnace but they will have to be changed when they are consumed or else the operator risks that the furnace will shut down due to lack of conductive electric circuit through the electrolyte. The optimal performance is for the graphite anodes to be replaced progressively throughout the furnace operation in order to cause a minimal disturbance to steady state operation. New anodes may be preheated but may still be much colder than the contents of the furnace and so when a new anode is added it has a cooling effect on the contents and disrupts the steady state of the chemical reaction. It is important that this operation be done quickly and efficiently but the anodes must also be placed very accurately in order to maintain a proper current density and an even current distribution. In the described system, the anode replacement may be accomplished by an automated system instead of manually by the furnace operators as is done in the traditional operations.

[0087] Robot arm for removal of spent anodes. In the described system, the spent anodes may be changed by the operation of a robotic arm controlled by the furnace control system. The robotic arm may be mounted on the mast or located on its own base. The robotic arm may incorporate vision module and / or load sensing in order to avoid damaging other components it may come in contact with. The furnace control system may coordinate with the other automated components including the cathode positioner, the mixer control arm, the automatic feed dispenser, and the automated metals extraction to ensure that the anode replacement does not interfere with the operation of the other components, that replacement is done quickly and safely. As described above, the anode mounting brackets may have a dedicated point where their robotic arm can attach and detach from the anodes in order to securely maintain a grip on the anode bracket. There is a strong magnetic attraction between the anodes and other furnace components due to the presence of a strong electromagnetic field generated by the furnace electric power system which can make it difficult for operators to manually manipulate the anodes. The robotic arm may have sufficient force to overcome the presence of this magnetic field because the anodes are changed while the furnace operation is live and both the top plate, anode holders, electrolyte and cathode are fully energized. Alternatively, power to the furnace may be reduced or stopped for a short period of time needed to detach the anodesfrom the top plate. Use of a mechanized robotic arm in this scenario provides obvious safety improvements to protect the furnace operators from both exposure to electric shock and the high temperature contents of the furnace and the spent anode parts which are removed from the furnace at 900°C or more. Once the anodes are removed from the furnace, they should be placed securely in a clean receptacle so that the electrolyte crust present on the anodes can be recovered. Both the electrolyte and the rare earth metal oxides dissolved in it are highly valuable and it is desirable to recover these from the surface of the anode after they have cooled so that the materials can be reintroduced to the furnace to maximize economic viability. The robotic arm can safely and quickly remove the spent anodes from the furnace to the receptacle and then pick and place a fresh anode accurately into the furnace in a precise location where it is then clamped in place by the anode holders. The robot can also scrape the surface of the crucible to remove any caked on electrolyte and / or sludge, and scoop any floating graphite pieces or sludge from the surface of the electrolyte. The robot may use different end effectors (attachments) for each of these actions.

[0088] Installation and positioning of fresh new anode. The anodes may be attached mechanically to the anode holding brackets which get clamped to the top plate. The clamping function may be accomplished by a mechanical clamp and actuator which may be controlled by the furnace control system. When the control system determines that an anode needs to be changed it may first operate the cathode holder, the mixer, and other components such that they are out of the way and will not interfere with the robotic arm which is used to grab on to the anode bracket. Once the robotic arm has securely gripped the anode bracket the control system may release the mechanical clamp on the bracket by use of the clamp actuator to release the anode bracket from the top plate. Once free, the robot arm can lift and remove the anode bracket and the remainder of the spent anode from the furnace. Once the robot arm has secured a fresh anode, the robot arm can place the anode into the furnace into the correct location and then the control system triggers the bracket clamping mechanism to clamp down on the bracket securely attaching it to the top plate and completing the electric circuit so that it can conduct electricity from the top plate through the bracket into the anode and then into the electrolytic salt bath. The robot arm may also be used to clean the surface of the furnace lid before new anode is installed by brushing it, blowing compressed air or using vacuum. This entire operation should be done quickly and efficiently avoiding any contact with other components or splashing of the molten electrolyte and once completed the control system will operate the furnace power system cathode positioner and mixer along with the feeding system to reestablish steady state by heating up the furnace as quickly as possible.

[0089] Sample collection automation. An important performance metric of the furnace is the purity and conversion rate of the rare earth oxides into rare earth metals. The way that the operators can determine both the purity and other factors of the metal is to take samples of the molten material at various stages in the smelting process so that these samples can be processed and provide this invaluable feedback to the operators on the system performance. Collecting these samples is dangerous due to the temperatures of the furnace, and therefore automation of sample collection is an important improvement to the smelting system. Sample collection system may use a rod or a tube inserted into the pool of molten electrolyte and / or molten metal. Once retracted, solidified sample may be removed from the sampling tool and analyzed.

[0090] Scrubber System. A scrubber system for the collection and neutralization of hazardous gases or vapors may be used with the furnace. The control system may control the scrubber, for example, to reposition the scrubber intake during extraction or anode replacement, which can allow for better positioning to collect the fumes during most of the operation without affecting the extraction and anode replacement. For example, the scrubber intake of the scrubber system could be physically moved out of the way upon receiving a signal from the control system.

[0091] Embodiments of the disclosure can be represented as a computer program product stored in a machine-readable medium (also referred to as a computer-readable medium, a processor-readable medium, or a computer usable medium having a computer-readable program code embodied therein). The machine-readable medium can be any suitable tangible, non-transitory medium, including magnetic, optical, or electrical storage medium including a diskette, compact disk read only memory (CD-ROM), memory device (volatile or non-volatile), or similar storage mechanism. The machine-readable medium can contain various sets of instructions, code sequences, configuration information, or other data, which, when executed, cause a processor to perform steps in a method according to an embodiment of the disclosure. Those of ordinary skill in the art will appreciate that other instructions and operations necessary to implement the described implementations can also be stored on the machine-readable medium. The instructions stored on the machine-readable medium can be executed by a processor or other suitable processing device, and can interface with circuitry to perform the described tasks.

[0092] It should be understood that numerous changes, modifications, and alternatives to the preceding disclosure can be made without departing from the scope of the disclosure. The preceding description, therefore, is not meant to limit the scope of the disclosure. Rather, the scope of the disclosure is to be determined only by the appendedclaims and their equivalents. It is also contemplated that structures and features in the present examples can be altered, rearranged, substituted, deleted, duplicated, combined, or added to each other.

[0093] The above-described embodiments are intended to be examples only. Alterations, modifications and variations can be effected to the particular embodiments by those of skill in the art. The scope of the claims should not be limited by the particular embodiments set forth herein, but should be construed in a manner consistent with the specification as a whole.

Claims

CLAIMS:

1. An electrolytic reduction smelting furnace system for producing rare earth metal, the system comprising: a) a furnace for smelting, the furnace comprising: i) a furnace cell for holding molten salt; and ii) anodes and a cathode for passing electric current; and b) an automated system for monitoring and controlling the furnace, the automated system comprising: i) a monitoring system comprising: a visual light camera for monitoring operation of the furnace; and a temperature sensor for monitoring operation of the furnace; and ii) a control system, for controlling the furnace, based on measurement from the monitoring system, the control system comprising: an electrical control system for controlling electrical power to the furnace; and a feed rate control system for controlling feed rate, feed schedule, or both.

2. The system of claim 1 , wherein the monitoring system further comprises a conductivity sensor for monitoring oxide concentration.

3. The system of claim 1 or 2, wherein the monitoring system further comprises a spectral sensor for sensing spectral data during operation of the furnace.

4. The system of any one of claims 1 to 3, wherein the monitoring system further comprises a thermal spectrum camera for mapping the surface temperatures.

5. The system of any one of claims 1 to 4, wherein the monitoring system comprises a cathode load sensor for sensing electrical load on a cathode positioning device, and wherein the control system comprises the cathode positioning device for positioning and moving the cathode within the furnace cell, based on measurement from the cathode load sensor, or feedback from motors that drive the cathode positioning system.

6. The system of any one of claims 1 to 5, further comprising an agitator for agitating the molten salt, wherein the monitoring system comprises an agitator load sensor for sensing load on the agitator.

7. The system of claim 6, wherein the control system controls the agitator, based on measurement from one or more of the agitator load sensor, feedback from motors that drive the agitator system, the cathode load sensor or motor feedback, the visual light camera, the thermal spectrum camera or the temperature sensor.

8. The system of any one of claims 1 to 7, further comprising an extraction system for extracting the rare earth metal from the furnace and controlled by the control system, wherein the monitoring system comprises an extraction system load sensor for sensing load on the extraction system, and wherein the control system controls the extraction system, based on measurement from the extraction system load sensor and / or the information from the visual light camera or the thermal spectrum camera.

9. The system of any one of claims 1 to 8, further comprising an anode retraction system for moving, replacing, and positioning at least one of the anodes, wherein the monitoring system comprises an anode retraction system load sensor for sensing load on the anode retraction system, and wherein the control system controls the anode retraction system, based on measurement from the anode retraction system load sensor.

10. The system of any one of claims 1 to 9, further comprising a sample collection system for collecting a sample from the furnace and controlled by the control system, wherein the monitoring system comprises a sample collection load sensor for sensing load on the sample collection system, and wherein the control system controls the sample collection system, based on measurement from the sample collection load sensor.11 . The system of any one of claims 1 to 10, wherein the automated system comprises a notification system for providing a notification when the monitoring system measures a parameter outside of a set range.

12. The system of any one of claims 1 to 11 , further comprising an automated feeding system having one or more load cell scales for determining the amount and rate at which one or more products are added to the furnace cell.

13. The system of claim 12, wherein the automated feeding system is configured to premix two or more of the products for providing to the furnace cell.

14. The system of any one of claims 1 to 13, wherein the furnace cell comprises a precast insulation shell having castable refractory cement rings.

15. The system of any one of claims 1 to 14, wherein the furnace cell comprises a fill of magnesium oxide powder.

16. The system of claim 14, wherein the castable refractory cement rings comprises a tongue and groove system for reducing drafts.

17. The system of any one of claims 1 to 16, wherein the furnace cell further comprises instrumentation mounting points for one or more of the agitator load sensor, the visual light camera, the thermal spectrum camera, conductivity sensor, or the temperature sensor.

18. The system of any one of claims 1 to 17, further comprising a multifunction mast configured to attach to one or more of the furnace cell, the monitoring system, orthe control system.

19. The system of claim 18, wherein the multifunction mast further comprises a cathode suspension mechanism for positioning the cathode and performing cathode load sensing.

20. The system of claim 18 or 19, wherein the multifunction mast further comprises an agitator mechanism for stirring furnace reagents and load sensing.

21. The system of any one of claims 1 to 20, further comprising a scrubber system controllable by the control system to reposition an intake of the scrubber system.

22. The system of any one of claims 1 to 21 , further comprising a robotic arm controllable by the control system to perform one or more of removing material and replacing the anodes.

23. A method of operating an electrolytic reduction smelting furnace system for producing rare earth metal, the method comprising: a) monitoring operation of the furnace, including visual monitoring, temperature monitoring, and spectral monitoring; and b) controlling operation of the furnace, including controlling electrical power to the furnace and controlling feed rate, feed schedule, or both, based on measurement from the monitoring.

24. The method of claim 23, further comprising interpreting, using artificial intelligence, current and historical monitoring data with analytical results for a molten bath and produced metal to produce control inputs; and wherein controlling operation of the furnace is based on the control inputs.

25. A process for producing rare earth metal, the process comprising: a) dissolving rare earth oxides in corresponding fluorides; b) producing rare earth metal using electrolytic reduction; c) monitoring the electrolytic reduction, including visual monitoring, temperature monitoring, and spectral monitoring; d) controlling the electrolytic reduction, including controlling electrical power to the electrolytic reduction and controlling feed rate, feed schedule, or both, based on measurement from the monitoring; and e) collecting the rare earth metal.