A method for synthesis of rare-earth oxychloride and production of rare-earth metal / alloy

Abstract

The present disclosure relates to a method for external synthesis of rare-earth oxychloride and production of rare-earth metal or alloy. The method comprises the steps of adding hydrochloric acid (HCl) to a portion of a pre-defined weight of rare-earth oxide (RE2O3) converting the portion of RE2O3 to rare-earth chloride hydrate (RECl3.xH2O). The method further comprises mixing the residual rare-earth oxide (RE2O3) with the RECl3.xH2O and heating the mixture to a temperature exceeding 300℃ to obtain rare-earth oxychloride (REOCl). The method includes making the obtained REOCl to react directly with a reductant or mixture of reductant and alloying element in a temperature of 600℃ - 1400℃ for reducing the rare-earth oxychloride (REOCl) to rare-earth metal or alloy; and upon cooling, treating the reduced mass of rare-earth metal or alloy with water and dilute acid to remove reaction byproducts such as calcium chloride (CaCl2) and calcium oxide (CaO).

Description

[0001] TITLE: A METHOD FOR SYNTHESIS OF RARE-EARTH OXYCHLORIDE AND PRODUCTION OF RARE-EARTH METAL / ALLOY

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to method for production of rare earth metal / alloy. Particularly, but not exclusively, the present disclosure is directed towards method for synthesis of rare-earth oxychloride in low temperature and production of rare-earth metal / alloy.

[0004] BACKGROUND

[0005] Rare earth (RE) alloys are highly valued in various industries for their exceptional properties and wide-ranging applications. These alloys consist of a blend of different metals as the base metal and rare earth elements such as Scandium (Sc), Lanthanum (La), Cerium (Ce), Praseodymium (Pr), Neodymium (Nd), Samarium (Sm), Gadolinium (Gd), Dysprosium (Dy) and others. The production of rare earth metal or alloy requires specific techniques to achieve the desired composition and properties. There is extensive use of Al-RE alloys in industries including aerospace, automotive, electronics, and renewable energy. The Al-RE alloy is highly sought after due to its lightweight properties, high strength-to-weight ratio, outstanding thermal conductivity, resistance to corrosion, and high temperatures. Rare earth-aluminum alloys are utilized in the manufacturing of aircraft components, automobile parts, electronic devices, and in applications where high-performance materials are essential.

[0006] A recent study looked into the possibility of employing an aluminum alloy with 12 weight percent Cerium (Ce) in automobile internal combustion (IC) engines. In comparison to standard aluminum alloys, the ALCe alloy showed the ability to endure greater temperatures, leading to increased fuel efficiency and decreased emissions. Further, it is anticipated that 2400 tons of rare earth elements (REEs) can be consumed in the automotive industry by substituting just 1% of current aluminum alloys with alloys containing 12% rare earths.

[0007] Conventionally, rare earth alloys are produced from rare earth metals. The production of rare earth metals involves several complex and often expensive technologies. Few of the existing notable methods used in the industry are illustrated below:

[0008] • Fluorination followed by Calciothermic Reduction: The process starts by combining hydrofluoric acid with compounds made of rare earth oxide or carbonate to create rare earth fluorides. The next step requires reacting the rare earth fluorides with calcium metal at high temperatures, a process known as calciothermic reduction. The rare earth metals can be separated from the fluorides using this technique, and then extracted.

[0009] • Fused Salt Electrolysis of Oxides: The method involves first converting rare earth oxide compounds into rare earth chlorides or fluorides. An electric current is then conducted though the solution after these chemicals have been dissolved in a molten salt electrolyte. While oxygen or fluorine gas is produced at the anode, rare earth ions flow towards the cathode and are reduced to their metallic form.

[0010] • Chlorination followed by Electro winning: In this process, rare earth oxide or carbonate compounds are chlorinated using chlorine gas or another chlorinating agent. The created rare earth chlorides are next cleaned and put though electro winning. By electro winning, rare earth metal ions are reduced and deposited onto the cathode by running an electric current though an electrolyte that contains rare earth chlorides.

[0011] It is important to note that the selection of the specific production method depends on factors such as the type of rare earth metals required, the desired purity, and the costeffectiveness of the process. However, the existing production methods often involve intricate steps and require specialized equipment and expertise, contributing to the overall expense of rare earth metal production.

[0012] There are few patent applications that describes the technique of production of rare-earth alloy. The patent documents CN2008102239844A discloses a method to produce Al-RE alloys by using fused salt electrolysis. However, the solubility of the RE oxide is less than 2 weight percent in the salt limit the rate of production. The capital cost is also high for this process.

[0013] Further, the patent document EP0170372A1 describes a method for producing rare earth metal by dissolving rare earth oxide in CaCh molten salt. However, during the process, the rare earth oxide is converted into oxychloride, resulting in the formation of CaO. The presence of CaO limits the effectiveness of calico-thermic reduction of the RE compound to metal since the reduction product also contains CaO. The solubility of CaO is limited to approximately 20 mol%.

[0014] Therefore, in order to avoid such problems, there is a need for a simple and cost-effective processes to produce rare earth metal / alloy that should overcome some of the problems of the prior art.

[0015] The present disclosure is directed to overcome one or more limitations stated above, and any other limitation associated with the prior arts.

[0016] SUMMARY

[0017] One or more shortcomings of the prior art are overcome, and additional advantages are provided through the present disclosure. Additional features and advantages are realized though the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

[0018] The present invention is directed to a method for external synthesis of rare-earth oxychloride and production of rare-earth metal / alloy. The method comprises the steps of adding hydrochloric acid (HC1) to a portion of a pre-defined weight of rare-earth oxide (RE2O3) as obtained for converting the portion of RE2O3 to rare-earth chloride hydrate (RECI3.XH2O), heating the obtained rare-earth chloride hydrate (RECI3.XH2O) for evaporating water. The method further comprises mixing the residual rare-earth oxide (RE2O3) with the rare-earth chloride hydrate (RECI3.XH2O) upon evaporation of water, and heating the mixture to a temperature exceeding 300°C to obtain rare-earth oxychloride (REOC1). The method includes making the obtained rare-earth oxychloride (REOC1) to react directly with calcium (Ca) or mixture of calcium (Ca) and alloying element in a temperature of 600°C - 1400°C for reducing the rare-earth oxychloride (REOC1) to rare-earth metal / alloy; and upon cooling, treating the reduced mass of rare- earth metal / alloy with water and dilute acid to remove reaction byproducts such as calcium chloride (CaCh) and calcium oxide (CaO).

[0019] In another embodiment, the present disclosure relates to a method for producing rare- earth metal / alloy from externally synthesized rare-earth oxychloride. The method comprises the steps of adding the externally synthesized rare-earth oxychloride (RE0C1) to molten calcium chloride (CaCh) or a mixture of calcium chloride (CaCh) and sodium chloride (NaCl) at temperature above 600°C with continuous stirring in presence of calcium (Ca) or mixture of calcium (Ca) and alloying element under controlled atmosphere for reducing the rare-earth oxychloride (RE0C1) to rare-earth metal / alloy, and upon cooling, treating the reduced mass of rare-earth metal / alloy with water and dilute acid to remove reaction byproducts such as calcium chloride (CaCh) and calcium oxide (CaO).

[0020] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

[0021] BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0022] The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and, together with the description, explain the disclosed principles. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system and / or methods in accordance with embodiments of the present subject matter are now described, by way of example only, and regarding the accompanying figures, in which:

[0023] Figure 1 illustrates a process flow diagram for production of rare-earth metal / alloy, in accordance with an embodiment of the present disclosure;

[0024] Figure 2 illustrates exemplary X-ray diffraction analysis (XRD) patterns of samples (LaOCl) heated at 300-900°C (including La2C>3 and synthesized LaC13.7H2O), in accordance with an embodiment of the present disclosure;

[0025] Figure 3 illustrates exemplary Scanning Electron Microscopy with Energy Dispersive X-Ray (SEM-EDX) analysis of the samples (LaOCl) heated at 500°C for 1 h, in accordance with an embodiment of the present disclosure;

[0026] Figure 4 illustrates exemplary X-ray diffraction analysis (XRD) patterns of samples (LaOCl) heated at 500°C and 700°C (including La2O3 and LaCh.VfLO), in accordance with an embodiment of the present disclosure;

[0027] Figure 5 illustrate exemplary Scanning Electron Microscopy with Energy Dispersive X- Ray (SEM-EDX) analysis of Al-La master alloy, in accordance with an embodiment of the present disclosure;

[0028] Figure 6 illustrate exemplary X-ray diffraction analysis (XRD) patterns of Al-30% La master alloy, in accordance with an embodiment of the present disclosure;

[0029] Figure 7 illustrate exemplary X-ray diffraction analysis (XRD) patterns of Al-60% La master alloy, in accordance with an embodiment of the present disclosure;

[0030] Figure 8 illustrate exemplary Scanning Electron Microscopy with Energy Dispersive X- Ray (SEM-EDX) analysis of Al-60%La master alloy, in accordance with an embodiment of the present disclosure; and

[0031] Figure 9 illustrate exemplary Scanning Electron Microscopy with Energy Dispersive X- Ray (SEM-EDX) analysis of Al-90%La master alloy, in accordance with an embodiment of the present disclosure.

[0032] Figure 10 illustrate exemplary X-ray diffraction analysis (XRD) patterns of Al-60% Nd master alloy, in accordance with an embodiment of the present disclosure; and

[0033] Figure 11 illustrate exemplary X-ray diffraction analysis (XRD) patterns of Al-60% Sm master alloy, in accordance with an embodiment of the present disclosure.

[0034] The figure depicts embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein. DETAILED DESCRIPTION

[0035] In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

[0036] While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however that it is not intended to limit the disclosure to the forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the disclosure.

[0037] The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non- exclusive inclusion, such that a setup, device or process that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or process. In other words, one or more elements in a system or apparatus proceeded by “comprises... a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.

[0038] Embodiments of the present disclosure provide a method for external synthesis of rare- earth oxychloride and production of rare-earth metal / alloy. The method comprises the steps of adding hydrochloric acid (HC1) to a portion of a pre-defined weight of rare-earth oxide (RE2O3) as obtained for converting the portion of RE2O3 to rare-earth chloride hydrate (RECI3.XH2O), heating the obtained rare-earth chloride hydrate (RECI3.XH2O) for evaporating water. The method further comprises mixing the residual rare-earth oxide (RE2O3) with the rare-earth chloride hydrate (RECI3.XH2O) upon evaporation of water, and heating the mixture to a temperature exceeding 300°C to obtain rare-earth oxychloride (REOC1). The method includes making the obtained rare-earth oxychloride (REOC1) to react directly with a reductant or mixture of reductant and alloying element in a temperature of 600°C - 1400°C for reducing the rare-earth oxychloride (REOC1) to rare-earth metal / alloy; and upon cooling, treating the reduced mass of rare-earth metal / alloy with water and dilute acid to remove reaction byproducts such as calcium chloride (CaCh) and calcium oxide (CaO).

[0039] In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.

[0040] A class of elements known as rare earth metals have special qualities including catalytic activity, luminescence, and magnetism that make them indispensable in many important technologies. They are used in the production of permanent magnets for electric motors, generators, and speakers, as well as in the manufacturing of rechargeable batteries, catalysts, high-performance alloys, and advanced electronics like smartphones, computers, and televisions.

[0041] As an example, aluminum rare earth alloys combine the lightweight and corrosionresistant properties of aluminum with the enhanced mechanical and thermal characteristics provided by rare earth elements. These alloys find applications in aerospace, automotive, and defence industries, where lightweight materials with high strength and heat resistance are crucial for fuel efficiency, structural integrity, and performance.

[0042] Fe-RE alloys containing Neodymium (Nd), Dysprosium (Dy), Praseodymium (Pr) can be used as a raw material for the production of permanent magnets. Sm-Co alloys can be used for the production of Sm-Co magnets. Similarly, Mg-RE alloys, Gd-Si alloys can use in some niche applications.

[0043] There are many advantages to developing domestic technology for rare earth metals and aluminum rare earth alloys. First off, it lessens reliance on foreign sources, as only a small number of nations account for a sizable share of the world's supply of rare earth metals. A community can secure a dependable supply chain and reduce the risks associated with geopolitical conflicts or trade interruptions by developing indigenous capabilities to mine, refine, and process these metals or create aluminum rare earth alloys.

[0044] One aspect of the invention relates to a synthesis process for RE0C1. The present invention introduces a novel and simple process that eliminates the need for high temperatures or the use of alkali or alkaline earth salt mediums as disclosed by the conventional techniques.

[0045] The following paragraphs describe the present disclosure with reference to Figure 1 - Figure 11. In the figures, Figure 1 is an exemplary method of the present disclosure and illustrates various steps of the method (100) for method for synthesis of rare-earth oxychloride in low temperature and production of rare-earth metal / alloy. The method (100) enables manufacturers to synthesize rare-earth oxychloride (REOC1) from rare- earth oxides and further produce rare-earth metal / alloy from the synthesized rare-earth oxychloride (REOC1). The method (100) therefore eliminates the requirement of involving high-temperature processes for obtaining REOC1 by reacting rare earth oxides with molten salts comprising alkali and alkaline earth chlorides. The method (100) also eliminates the requirement of additional processing such as water washing to eliminate calcium chloride (CaCh), mild acid leaching to eliminate calcium oxide (CaO) for the recovery of REOC1. In one embodiment, the method (100) according to present disclosure aids in mitigating the problems of limited solubility of CaO in a CaCh melt and effect of amount of CaO in solubility of calcium (Ca) that is used as reductant. Therefore, the present invention eliminates the need for high temperatures or the use of alkali or alkaline earth salt mediums.

[0046] However, it is understood by a person skilled in the art that the size and configuration of the required set of machinery for accomplishing the method (100) may be variable in accordance with the requirement of the different types of installation environment. Any such variation / modification shall be construed to be within the scope of the present disclosure. As illustrated in Figure 1 (a solid state reduction process), the method (100) comprises one or more blocks to be performed for synthesis of rare-earth oxychloride in low temperature and production of rare-earth metal or alloy from the rare-earth oxychloride. The order in which the method (100) is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the method. Additionally, individual blocks may be deleted from the methods without departing from the spirit and scope of the subject matter described herein.

[0047] At block (102), hydrochloric acid (HC1) is added to a portion of a pre-defined weight of rare-earth oxide. In one embodiment, hydrochloric acid (HC1) is added to a portion of a pre-defined weight of rare-earth oxide (RE2O3) as obtained for converting the portion of RE2O3 to rare-earth chloride hydrate (RECI3.XH2O). In an example, the REOC1 synthesis is achieved by addition of HC1 to convert 1 / 3 of the rare-earth oxide as obtained. The addition of HC1 converts the part of RE2O3 to rare-earth chloride hydrate (RECI3.XH2O) as depicted in the following reactions:

[0048] 1 / 3 RE2O3 + 2HC1 2 / 3REC13.XH2O

[0049] In another embodiment, commercial RECI3.XH2O can also be used as a raw material along with RE2O3 for the production of REOC1.

[0050] At block (104), water from the dissolved solution is evaporated for obtaining rare-earth chloride hydrate. In one embodiment, the dissolved solution is heated in certain temperature for evaporating water from the dissolved solution and obtaining rare-earth chloride hydrate.

[0051] At block (106), the residual rare-earth oxide is mixed to the obtained rare-earth chloride hydrate. In one embodiment, the residual 2 / 3 of the obtained rare-earth oxide is mixed with the rare-earth chloride as produced upon treating the 1 / 3 portion the rare-earth oxide with hydrochloric acid (HC1).

[0052] At block (108), the mixture heated to temperature exceeding 300°C for converting to rare-earth oxychloride. In one embodiment, the mixture of the rare-earth oxide and the rare-earth chloride is heated to temperature exceeding 300°C and in a range of 300°C - 1000°C. The heating process facilitated the conversion of the mixture of RE2O3 and RECI3 into the rare-earth oxychloride (RE0C1) as depicted in the following reactions.

[0053] 2 / 3 RE2O3 + 2 / 3REC13.XH2O 2RE0C1 + XH2O

[0054] At block (110), the rare-earth oxychloride is made to react with calcium or calcium along with alloying element for extracting rare-earth metal or alloy. In one embodiment, the obtained rare-earth oxychloride (REOC1) is reacted directly with a reductant or reductant (Ca, Mg, Al) along with alloying element in a temperature of 600°C - 1400°C under inert atmosphere for reducing rare-earth oxychloride (REOC1) to rare-earth metal or alloy, calcium chloride (CaCh), and calcium oxide (CaO) as depicted in the following reaction:

[0055] 2REOC1 + 3Ca = 2RE + 2CaO + CaCh

[0056] 2REOC1 + 3Ca + alloying element = 2RE-alloy + 2CaO + CaCh

[0057] Further, upon cooling, the reduced mass of rare-earth metal or alloy is treated with water to remove one of the reaction product, i.e. CaCh followed by a weak acid leaching such as dilute acetic acid for the removal of CaO / Ca(OH)2 to yield RE metal or alloy. The acid used for removal of CaO / Ca(OH)2 can be one of organic or inorganic acid such as citric, acetic, HC1, H2SO4.

[0058] The calcium content in the alloy can be reduced by carefully adjusting the Ca to REOC1 ratio during the alloy formation. Moreover, to achieve even lower calcium levels, two additional methods can be employed: either subjecting the alloy to vacuum treatment, which helps remove additional calcium impurities by exposing the alloy to low pressure conditions, or by adding it to a specific dilute alloy formation designed to selectively remove calcium from the alloy.

[0059] Therefore, the proposed process eliminates the requirement of addition of extra CaCh as a reaction medium or a solvent for dissolving CaO. As a result, the process becomes highly energy-efficient and straightforward. The need to heat a large volume of CaCh is also eliminated, reducing energy consumption significantly. Additionally, the requirement for the removal and recovery of large volumes of CaCh is also eliminated. Thus, the solid-state process shows to be a major improvement in addressing the previous limitations and streamlining the overall production of rare-earth metal or alloy.

[0060] The solid-state process plays a crucial role in shaping and transforming metals and alloys without involving melting or liquid phases. These processes are used to modify the microstructure, mechanical properties, and overall characteristics of metals.

[0061] In another embodiment, RE0C1 is used as an input material for the synthesis of rare earth metal or alloy production. RE0C1 is added to molten CaCh or a mixture of CaCh-NaCl at temperatures above 800°C with continuous stirring in the presence of Ca under inert atmosphere.

[0062] 2RE0C1 + 3Ca = 2RE + 2CaO + CaCh

[0063] Therefore, the method for producing rare-earth metal or alloy from externally synthesized rare-earth oxychloride, comprises the step of adding the externally synthesized rare-earth oxychloride (RE0C1) to molten calcium chloride (CaCh) or a mixture of calcium chloride (CaCh) and sodium chloride (NaCl) at temperature above 800°C with continuous stirring in presence of calcium (Ca) under controlled atmosphere for reducing the rare-earth oxychloride (RE0C1) to rare-earth metal or alloy. The method also includes treating the reduced mass of rare-earth metal or alloy, upon cooling, with water and dilute weak acid to remove reaction byproducts such as calcium chloride (CaCh) and calcium oxide (CaO).

[0064] The production of rare earth (RE) metal is influenced by the limited solubility of CaO in a CaCh melt (approximately 20 mol%). Additionally, the solubility of calcium, which is used as a reductant in the process, is also affected by the amount of CaO. To mitigate these limitations of the existing technology, an external synthesis of REOC1 is carried out and used as a substitute for RE2O3. Such substitution reduces the production of CaO since CaO is only generated during the reduction phase, not during dissolution. Furthermore, the consumption of CaCh for the conversion of RE2O3 to REOC1 also can be avoided with the proposed process. The CaCh required for the dissolution of CaO formed during reaction of RE2O3 with CaCh and during reduction of REOC1 with Ca is about 5.5 kg per kg RE metal production. However, in the present invention the requirement of CaCh is brought down to 3 kg. As a result, this modification significantly increases productivity by about 50%.

[0065] Experimental Details:

[0066] According to the present invention's embodiments, the present process's advantages and benefits would become more apparent from the experimental details below to a person skilled in the art.

[0067] Example 1:

[0068] 5g La2C>3 was dissolved in 9.08g acid (37% HC1) and kept on hot plate for the removal water at 90 °C for 6 h. The residue (LaCh.xfTO) obtained was mixed with 10g of La2Os and heated at different temperatures from 300 to 900°C for 1 h to 4 hs. The obtained samples were examined using X-Ray diffraction (XRD) and scanning electron microscopy-energy dispersive X-ray (SEM-EDX) analysis as illustrated in Figure 2 and Figure 3 respectively. LaOCl was successfully synthesized, except at low temperature and at less duration. The LaOCl was formed even at 300°C for 4 h duration. However, at 400°C, even at Ih reaction could convert everything to LaOCl. At higher temperature (>800°C) LaOCl started decomposing and converting back to La2O3. About 17.5g of LaOCl was formed at 500°C for 1 h.

[0069] Example 2:

[0070] About 1g of La2Os was mixed with a chemical grade 1.13g of LaC13.7H2O and heated to 500°C and 700°Cfor 1 h. After the reaction, the product was weighed about 1.7g of LaOCl. It was characterized with XRD and confirmed the formation of LaOCl, which is illustrated in Figure 4.

[0071] Example 3:

[0072] NdOCl was produced by combining 1.23g of HC1 acid with 2g of Nd2Os, leading to the conversion of one-third of the Nd2Os. Subsequently, the mixture was heated to a temperature of 500°C and maintained at this temperature for one h. The addition of HC1 converts the part of Nd2Os to NdCh.xH2O. The heating process facilitated the conversion of the mixture of Nd2Os and NdCh.xH2O into NdOCl, as per the following reactions:

[0073] 1 / 3 Nd2O3+ 2HC1 2 / 3 NdCl3.xH2O 2 / 3 Nd2O3+ 2 / 3 NdCl3.xH2O 2 NdOCl + xH2O

[0074] Example 4:

[0075] 1.37g LaOCl was mixed with 0.43g Ca and 9g Al. 9g CaCl2and 1g NaCl was mixed and melted at 900°C. After melting, the LaOCl, Al and Ca mixture was added to the melt and continuously stirred for 1 h. This process was conducted under argon atmosphere. After cooling the melt, the sample was washed under running water to remove CaCl2and fine Ca(OH)2. As illustrated in Figure 5, the SEM-EDX analysis of Al-La master alloy confirmed that the alloy contains around 6% La along with some Ca. However, by optimizing stirring and other conditions about 10% La alloy can be obtained.

[0076] Example 5:

[0077] LaOCl was mixed with reductant (10% excess of stoichiometric Ca) and required amount of Al powders to produce different alloys. The composition of different mixtures is shown in the Table 1.

[0078] Table 1

[0079] After mixing in an agate mortar-pestle, the mixture was pelletized with die and punch using a press and placed in an alumina boat and kept it in a horizontal tubular furnace at 900°C for 1 h under argon atmosphere to form the Al-La alloys as per the following reaction:

[0080] 2 LaOCl + 3Ca + yAl yAl-La + 2CaO + CaCl2

[0081] About more than 98% purity Al-La alloy was achieved and produced Al-30%La, Al-60%La and Al- 90% La successfully. The reduced mass was further treated with flowing water to remove CaCl2along with some CaO. After CaCl2removal, the alloy was treated with 10% acetic acid to remove any leftover CaCl2and CaO / Ca(OH)2. After CaO and CaCl2removal, the alloy was analysed with SEM-EDX analysis and XRD analysis. Figure 5 and Figure 6 show XRD analysis of Al-30% La and AL 60% La alloys respectively, and Figure 7 and Figure 8 show SEM-EDX analysis of Al- 60% La and Al- 90% La alloys respectively.

[0082] Example 6:

[0083] NdOCl, Ca and aluminum powders were thoroughly mixed and pelletized as discussed in the above example (5). The pellet was placed in the alumina boat and kept at 900°C for 1 h under argon atmosphere. The alumina boat was removed from the furnace once it got cool down. CaCh and CaO from the mixture was removed by water and dilute acetic acid washing as explained in the previous examples. Figure 10 depicts the XRD pattern of Al-60% Nd alloy. About 97% purity Nd- Al alloy was recovered. In a similar way Nd-Fe alloy can also be produced, such alloy could be combined with B and melted to obtain Nd-Fe-B magnet raw material. The Nd-Al alloy was formed according to the following reaction.

[0084] 2NdOCl + 3Ca + xAl Nd-xAl + 2CaO + CaCh

[0085] Example 7:

[0086] SmOCl, Ca and Al powders were thoroughly mixed and pelletized as discussed in the above example (5). The pellet was placed in the alumina boat and kept at 900°C for 1 h under argon atmosphere. The alumina boat was removed from the furnace once it got cool down. CaCh and CaO from the mixture was removed by water and dilute acetic acid washing as explained in the previous examples. Figure 11 depicts the XRD pattern of Al-60% Sm alloy. About 97% purity Sm-Al alloy was recovered. In a similar way Sm-Co alloy can also be produced, such alloy could be combined with Fe and melted to obtain Sm-Co magnet raw material. The Sm-Al alloy was formed according to the following reaction.

[0087] 2SmOCl + 3Ca + x Al Sm-xAl + 2CaO + CaCh

[0088] Advantages of the present disclosure:

[0089] The present invention, by introducing pre-synthesized rare-earth oxychloride into the process, enhances the productivity as the salt demonstrates a higher ability to dissolve CaO. Such modification overcomes the issue of CaO formation, allowing for a more efficient calico-thermic reduction and increasing the overall output of the process.

[0090] The present invention also tackles the solubility limitation of CaO, even when it is formed during calico-thermic reduction. Consequently, a solid-state process has been devised wherein RE0C1 can be directly reduced using calcium, with or without the inclusion of alloying elements or their oxides. Such innovative approach enables the direct reduction of RE0C1, bypassing the use of CaCh to melt and overcoming the challenges associated with CaO solubility.

[0091] The present invention for the production rare earth alloy is indigenous technology of strategically important rare earth metals or rare earth alloys which can have significant implications for a society's technological advancement, economic development, and national security. These metals and alloys can be considered as "vitamins" for a society due to their critical role in various high-tech industries and applications.

[0092] The present invention also incurs cost of RE0C1 production that is significantly lower than REF3 production and also consumption of acid or chlorine is low.

[0093] In the detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The description is, therefore, not to be taken in a limiting sense.

[0094] While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Claims

Claims:

1. A method (100) for external synthesis of rare-earth oxychloride and production of rare- earth metal / alloy, the method comprising: adding (102) hydrochloric acid (HC1) to a portion of a pre-defined weight of rare-earth oxide (RE2O3) as obtained for converting the portion of RE2O3 to rare-earth chloride hydrate (RECI3.XH2O); heating (104) the obtained rare-earth chloride hydrate (RECI3.XH2O) for evaporating water; mixing (106) the residual rare-earth oxide (RE2O3) with the rare-earth chloride hydrate (RECI3.XH2O) upon evaporation of water; heating (108) the mixture to a temperature in the range of 300°C -800°C to obtain rare-earth oxychloride (REOC1); making (110) the obtained rare-earth oxychloride (REOC1) to react directly with reductant in a temperature of 600°C - 1400 °C for reducing the rare-earth oxychloride (REOC1) to rare-earth metal; and upon cooling, treating the reduced mass of rare-earth metal with water and dilute acid to remove reaction byproducts such as calcium chloride (CaCh) and calcium oxide (CaO).

2. The method (100) as claimed in claim 1, wherein the method further comprises the steps for obtaining rare-earth alloy by: making the obtained rare-earth oxychloride (REOC1) to react directly with reductant and alloying element in a temperature above 600°C - 1400°C for reducing the rare-earth oxychloride (REOC1) to rare-earth alloy; and upon cooling, treating the reduced mass of rare-earth alloy with water and dilute acid to remove reaction byproducts such as calcium chloride (CaCh) and calcium oxide (CaO).

3. The method (100) as claimed in claim 1, wherein the pre-defined weight of rare-earth oxide (RE2O3) is % of the total weight of obtained rare-earth oxide (RE2O3) and the residual % of the total weight of obtained rare-earth oxide (RE2O3) is mixed with the rare-earth chloride hydrate (RECI3.XH2O).

4. The method (100) as claimed in claim 1, wherein the RE can be a group of 15 elements in the periodic table in Lanthanide series including scandium and yttrium.

5. The method (100) as claimed in claim 2, making the obtained rare-earth oxychloride (REOC1) to react directly with reductant such as Ca, Mg, Al etc., and alloying element in a temperature above 600°C - 1400°C for reducing the rare-earth oxychloride (REOC1) to rare-earth alloy.

6. The method (100) as claimed in claim 2, making the obtained rare-earth oxychloride (REOC1) to react directly with reductant and alloying element such as Al, Mg, Zn, Fe, Co, Si etc., in a temperature above 600°C - 1400°C for reducing the rare-earth oxychloride (REOC1) to rare-earth alloy7. The method (100) as claimed in claim 2, wherein the calcium content in the alloy is optimized by adjusting the reductant to the rare-earth oxychloride (REOC1) ratio during alloy formation.

8. The method (100) as claimed in claim 2, wherein the acid used for removal of CaO / Ca(OH)2 one of organic or inorganic acid such as citric, acetic, HC1, H2SO4.

9. A method for producing rare-earth metal or alloy from externally synthesized rare-earth oxychloride, the method comprising: adding the externally synthesized rare-earth oxychloride (REOC1) to molten calcium chloride (CaCh) or a mixture of calcium chloride (CaCh) and sodium chloride (NaCl) at temperature above 600°C - 1400°C with continuous stirring in presence of calcium (Ca) under inert atmosphere for reducing the rare-earth oxychloride (REOC1) to rare-earth metal; upon cooling, treating the reduced mass of rare-earth metal with water and dilute acid to remove reaction byproducts such as calcium chloride (CaCh) and calcium oxide (CaO).

10. The method as claimed in claim 8, wherein the method further comprises the steps for obtaining rare-earth alloy by: adding the externally synthesized rare-earth oxychloride (REOC1) to molten calcium chloride (CaCh), or a mixture of calcium chloride (CaCh) and sodium chloride (NaCl), and alloying element at temperature above 800°C - 1000°C with continuous stirring in presence of calcium (Ca) under inert atmosphere for reducing the rare-earth oxychloride (REOC1) to rare-earth alloy; upon cooling, treating the reduced mass of rare-earth alloy with water anddilute acid to remove reaction byproducts such as calcium chloride (CaCh) and calcium oxide (CaO).

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