WO2023244732A1 - Procédés et systèmes de réduction d'oxydes de métaux des terres rares - Google Patents

Procédés et systèmes de réduction d'oxydes de métaux des terres rares Download PDF

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Publication number
WO2023244732A1
WO2023244732A1 PCT/US2023/025424 US2023025424W WO2023244732A1 WO 2023244732 A1 WO2023244732 A1 WO 2023244732A1 US 2023025424 W US2023025424 W US 2023025424W WO 2023244732 A1 WO2023244732 A1 WO 2023244732A1
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WIPO (PCT)
Prior art keywords
rare earth
powder
earth oxide
powder mixture
crucible
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PCT/US2023/025424
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English (en)
Inventor
Matthew SZYMSKI
Marci SHELTON
Eric Van Abel
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Shine Technologies, Llc
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Publication of WO2023244732A1 publication Critical patent/WO2023244732A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B5/00—General methods of reducing to metals
    • C22B5/02—Dry methods smelting of sulfides or formation of mattes
    • C22B5/16—Dry methods smelting of sulfides or formation of mattes with volatilisation or condensation of the metal being produced
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
    • C22B1/24—Binding; Briquetting ; Granulating
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B59/00—Obtaining rare earth metals

Definitions

  • Lutetium-177 (Lu-177) is a radioisotope that is used in the treatment of neuro endocrine tumors, prostate, breast, renal, pancreatic, and other cancers. In the coming years, approximately 70,000 patients per year will need Lu-177 during their medical treatments. Some current techniques for isolating and purifying Lu-177 use ytterbium. [0004] Accordingly, a need exists for improved techniques for isolating ytterbium metal, which may be used in the separation and purification of radioisotopes, such as Lu-177.
  • a method includes forming a powder mixture from a rare earth oxide powder and a lanthanum powder, heating the powder mixture in a crucible assembly positioned in a reduced pressure environment, wherein heating the powder mixture comprises applying heat using a heating element and heating the powder mixture reduces the rare earth oxide powder into a rare earth metal that collects on a collection region of the crucible assembly.
  • the method also includes monitoring a pressure in the reduced pressure environment using a pressure sensor and reducing the heat applied by the heating element to the powder mixture when the pressure in the reduced pressure environment is above a threshold pressure.
  • a second aspect includes the method of the first aspect, wherein the rare earth oxide powder comprises an ytterbium oxide powder or a gadolinium oxide powder and the rare earth metal comprises an ytterbium metal or a gadolinium metal.
  • a third aspect includes the method of the first or second aspects, further comprising halting application of heat by the heating element to the powder mixture when the pressure in the reduced pressure environment is above the threshold pressure.
  • a fourth aspect includes the method of any of the previous aspects, further comprising resuming application of heat from the heating element to the powder mixture when the pressure of the reduced pressure environment is at or below the threshold pressure.
  • a fifth aspect includes the method of any of the previous aspects, wherein the powder mixture is a homogeneous mixture of rare earth oxide powder and lanthanum powder.
  • a sixth aspect includes the method of any of the previous aspects, wherein heating the powder mixture retains lanthanum in a reaction region of the crucible assembly.
  • a seventh aspect includes the method of any of the previous aspects, further comprising cooling the collection region of the crucible assembly while heating powder mixture to promote collection of the rare earth metal on the collection region.
  • An eighth aspect includes the method of any of the previous aspects, wherein the threshold pressure is in a range of from 1x10 -6 torr to 1 x10 -2 torr.
  • a ninth aspect includes the method of any of the previous aspects, wherein the heating element comprises an induction heating element.
  • a tenth aspect includes the method of any of the previous aspects, wherein when heating the powder mixture, the powder mixture is positioned in a reaction crucible of the crucible assembly, the crucible assembly further comprising a collection crucible, wherein the collection crucible is in the collection region of the crucible assembly.
  • An eleventh aspect includes the method of the tenth aspect, further comprising, when heating the powder mixture, cooling the collection crucible.
  • a twelfth aspect includes the method of the tenth aspect or eleventh aspect, wherein the crucible assembly further comprises a support sleeve and an insulative holder; the collection crucible extends into a first end of the support sleeve; and the reaction crucible extends into a first end of the insulative holder.
  • a thirteenth aspect includes the method of any of the tenth through twelfth aspects, wherein the support sleeve comprises graphite.
  • a fourteenth aspect includes the method of any of the tenth through thirteenth aspects, wherein the insulative holder comprises a ceramic material.
  • a fifteenth aspect includes the method of any of the tenth through fourteenth aspects, further comprising, when heating the powder mixture, cooling the collection crucible using a cold finger extending into a second end of the support sleeve and contacting the collection crucible.
  • a sixteenth aspect includes the method of any of the tenth through fifteenth aspects, wherein when heating the powder mixture, a stepper is coupled to a second end of the insulative holder, wherein the stepper is configured to translate the crucible assembly within the reduced pressure environment.
  • a seventeenth aspect includes the method of any of the tenth through sixteenth aspects, wherein the collection crucible is removably coupled to the reaction crucible by a collar.
  • An eighteenth aspect includes the method of the seventeenth aspect, wherein the collar comprises a refractory metal.
  • a nineteenth aspect includes the method of any of the tenth through eighteenth aspects, wherein the reaction crucible and the collection crucible each comprise a refractory metal.
  • a twentieth aspect includes the method of any of the tenth through nineteenth aspects, wherein an inner chamber of the reaction crucible faces an inner chamber of the collection crucible.
  • a twenty-first aspect includes the method of any of the previous aspects, further comprising orienting a collection substrate to face the collection region of the crucible assembly holding the rare earth metal; and sublimating the rare earth metal in an environment at a temperature in a range of from 400o C to 3000o C to transfer the rare earth metal from the collection region of the crucible assembly to a collection surface of the collection substrate, wherein the rare earth metal comprises an ytterbium metal.
  • a twenty-second aspect includes the method of the twenty-first aspect, further comprising removing the ytterbium metal from the collection substrate; and irradiating the ytterbium metal with neutrons to form an irradiated solid composition comprising ytterbium and lutetium.
  • a twenty-third aspect includes the method of the twenty-second aspect, further comprising sublimating ytterbium from the irradiated solid composition in an environment at a temperature in a range of from 400o C to 3000o C to leave a lutetium composition comprising a higher weight percentage of lutetium than was present in the irradiated solid composition.
  • a twenty-fourth aspect includes the method of the twenty-third aspect, wherein the environment is an inert or reduced pressure environment.
  • a twenty-fifth aspect includes the method of the twenty-third or twenty-fourth aspects, wherein the temperature is less than 700o C.
  • a twenty-sixth aspect includes the method of any of the previous aspects, wherein the rare earth oxide powder comprises rare earth oxide particles comprising an average maximum cross-sectional dimension of 5 ⁇ m or less and a particle size distribution in which 90% or more of the rare earth oxide particles comprise a maximum cross-sectional dimension of 10 ⁇ m or less.
  • a method includes forming a powder mixture from a rare earth oxide powder and a lanthanum powder; wherein the rare earth oxide powder comprises rare earth oxide particles comprising an average maximum cross-sectional dimension of 5 ⁇ m or less and a particle size distribution in which 90% or more of the rare earth oxide particles comprise a maximum cross-sectional dimension of 10 ⁇ m or less; agitating the powder mixture to increase a distribution uniformity of the rare earth oxide powder and the lanthanum powder in the powder mixture; and heating the powder mixture in a crucible assembly positioned in a reduced pressure environment, wherein heating the powder mixture reduces the rare earth oxide powder into a rare earth metal that collects on a collection region of the crucible assembly.
  • a twenty-eighth aspect includes the method of the twenty-seventh aspect, wherein, subsequent to agitating the powder mixture, the powder mixture comprises a homogeneous mixture of the rare earth oxide powder and the lanthanum powder.
  • a twenty-ninth aspect includes the method of the twenty-seventh or twenty-eighth aspects, wherein the rare earth oxide particles comprise an average maximum cross-sectional dimension of 3 ⁇ m or less.
  • a thirtieth aspect includes the method of any of the twenty-seventh through twenty- ninth aspects, wherein the rare earth oxide particles comprise an average maximum cross-sectional dimension in a range of 1 ⁇ m to 3 ⁇ m.
  • a thirty-first aspect includes the method of any of the twenty-seventh through thirtieth aspects, wherein the particle size distribution of the rare earth oxide powder is such that 95% or more of the rare earth oxide particles comprise a maximum cross-sectional dimension of 10 ⁇ m or less.
  • a thirty-second aspect includes the method of any of the twenty-seventh through thirty-first aspects, wherein the particle size distribution of the rare earth oxide powder is such that 90% or more of the rare earth oxide particles comprise a maximum cross-sectional dimension of 5 ⁇ m or less.
  • a thirty-third aspect includes the method of any of the twenty-seventh through thirty-second aspects, wherein the particle size distribution of the rare earth oxide powder is such that 95% or more of the rare earth oxide particles comprise a maximum cross-sectional dimension of 5 ⁇ m or less.
  • a thirty-fourth aspect includes the method of any of the twenty-seventh through thirty-third aspects, wherein the lanthanum powder comprises lanthanum particles comprising an average maximum cross-sectional dimension of 90 ⁇ m or less.
  • a thirty-fifth aspect includes the method of any of the twenty-seventh through thirty-fourth aspects, wherein when heating the powder mixture, the crucible assembly is positioned in a reduced pressure environment.
  • a thirty-sixth aspect includes the method of any of the twenty-seventh through thirty-fifth aspects, further comprising, prior to agitating the powder mixture, positioning the powder mixture in a reaction crucible of the crucible assembly such that the powder mixture is agitated in the reaction crucible, and subsequent to agitating the powder mixture, packing the powder mixture to increase a density of the powder mixture in the reaction crucible.
  • a thirty-seventh aspect includes the method of any of the twenty-seventh through thirty-sixth aspects, further comprising, prior to forming the powder mixture, milling the rare earth oxide powder to increase a sphericity the rare earth oxide particles of the rare earth oxide powder.
  • a thirty-eighth aspect includes the method of the thirty-seventh aspect, wherein milling the rare earth oxide powder comprises jet milling the rare earth oxide powder.
  • a thirty-ninth aspect includes the method of the thirty-seventh or thirty-eighth aspects, wherein, subsequent to milling the rare earth oxide powder, the ratio of the maximum cross-sectional dimension to the minimum cross-sectional dimension of 90% of more of the rare earth oxide particles of the rare earth oxide powder is 2:1 or less.
  • a fortieth aspect includes the method of any of the thirty-seventh through the thirty- ninth aspects, wherein, subsequent to milling the rare earth oxide powder, the ratio of the maximum cross-sectional dimension to the minimum cross-sectional dimension of 90% of more of the rare earth oxide particles of the rare earth oxide powder is 1.5:1 or less.
  • a forty-first aspect includes the method of any of the twenty-seventh through fortieth aspects, wherein the ratio of the maximum cross-sectional dimension to the minimum cross-sectional dimension of 90% of more of the rare earth oxide particles of the rare earth oxide powder is 2:1 or less.
  • a forty-second aspect includes the method of any of the twenty-seventh through forty-first aspects, wherein the ratio of the maximum cross-sectional dimension to the minimum cross-sectional dimension of 90% of more of the rare earth oxide particles of the rare earth oxide powder is 1.5:1 or less.
  • a forty-third aspect includes the method of any of the twenty-seventh through forty-second aspects, wherein the rare earth oxide powder comprises an ytterbium oxide powder or a gadolinium oxide powder and the rare earth metal comprises an ytterbium metal or a gadolinium metal.
  • FIG. 1 schematically depicts a crucible assembly for rare earth metal oxide reduction, according to one or more embodiments shown and described herein;
  • FIG. 2 schematically the crucible assembly of FIG.
  • FIG.3 schematically depicts a collar of the crucible assembly of FIG.1, according to one or more embodiments shown and described herein;
  • FIG.4A schematically depicts an insulative holder of the crucible assembly of FIG.
  • FIG.4B schematically depicts a cross section of the insulative holder of FIG.4A along line 4B-4B, according to one or more embodiments shown and described herein;
  • FIG.5A schematically depicts a support sleeve of the crucible assembly of FIG.1, according to one or more embodiments shown and described herein;
  • FIG. 5B schematically depicts a cross section of the support sleeve of FIG. 5A along line 5B-5B, according to one or more embodiments shown and described herein.
  • embodiments of the present disclosure are directed to methods of reducing rare earth oxides to rare earth metals.
  • embodiments of the present disclosure are directed to methods of reducing a rare earth oxide, such as ytterbium oxide, to a rare earth metal, such as ytterbium metal, in a crucible assembly.
  • the crucible assembly may comprise a reaction crucible fluidly coupled to a collection crucible such the fluids, including gases, may flow between the reaction crucible and the collection crucible, for example, from the reaction crucible to the collection crucible.
  • a powder mixture comprising a rare earth oxide powder, such as an ytterbium oxide powder, and a lanthanum powder may be heated in the crucible assembly positioned in a reduced pressure environment by applying heat to a reduction region of the crucible assembly using a heating element. Heating the powder mixture reduces the rare earth oxide powder into a rare earth metal that collects on a collection region of the crucible assembly.
  • the efficiency and quality of the reduction process may be improved by operating within certain pressure and temperature ranges.
  • the efficiency and quality of the reduction process may also be improved by increasing the distribution uniformity of the powder mixture, reducing the particle size of the rare earth oxide particles, and increasing a sphericity of the rare earth oxide particles.
  • the reduction techniques described herein take an advantage of the large differences in vapor pressure between the produced rare-earth metal and the reductant, along with any potential by-products or other impurities. These vapor pressure differences also purify the reduced rare-earth metal by separating the reduced metal from the by- products and impurities.
  • the reduced rare-earth metal may have a purity of 99% or greater.
  • the method described herein includes a pressure monitoring step to continuous or intermittently measure the pressure in the reduced pressure environment such that the heat applied to the powder mixture may be reduced and/or removed when the pressure in the reduced pressure environment is above a threshold pressure, such as a threshold pressure in a range of from 1x10 -6 torr and 5 x10 -5 torr.
  • Lu-177 is useful for many medical applications, because during decay it emits a low energy beta particle that is suitable for treating tumors. It also emits two gamma rays that can be used for diagnostic testing. Isotopes with both treatment and diagnostic characteristics are termed “theranostic.” Not only is Lu-177 theranostic, but it also has a 6.65-day half-life, which allows for more complicated chemistries to be employed, as well as allowing for easy global distribution.
  • Lu-177 also exhibits chemical properties that allow for binding to many bio molecules, for use in a wide variety of medical treatments.
  • the processes described herein provide efficient and effective techniques for obtaining ytterbium metal from ytterbium oxide, which is easier to obtain than ytterbium metal, such that the ytterbium metal may be used to isolate isotopes of interest, such as Lu-177.
  • the technique described herein may be used to obtain other rare earth metals from their oxides, such as gadolinium, samarium, europium, and terbium.
  • the crucible assembly 100 comprises a reaction region 102 and a collection region 104, which may be opposite the reaction region 102.
  • the crucible assembly 100 comprises a reaction crucible 110 in the reaction region 102 and a collection crucible 120 in the collection region 104.
  • the reaction crucible 110 is removably coupled to the collection crucible 120 by a collar 105.
  • the collar 105 is depicted in more detail in FIG.3 and may include one or more secondary flowpaths to facilitate pressure changes within the reaction crucible 110 and the collection crucible 120, for example, pressure reduction when the crucible assembly is positioned in a chamber 15 of the sublimation/distillation system 10. That is, in some embodiments the collar 105 may provide a baffle functionality.
  • the reaction crucible 110, the collection crucible 120 and the collar 105 each comprise a refractory metal.
  • Example refractory metals include tungsten, molybdenum, niobium, tantalum, and rhenium.
  • the reaction crucible 110 is coupled to the collection crucible 120 such that the reaction crucible 110 is fluidly coupled to the collection crucible 120, allowing fluids, such as sublimated metal gas, to flow between the reaction crucible 110 and the collection crucible 120, for example, from the reaction crucible 110 to the collection crucible 120.
  • the reaction crucible 110 is coupled to the collection crucible 120 such that the inner surfaces and inner chambers of each face one another.
  • the crucible assembly 100 may further comprise an insulative holder 130 (FIGS. 4A and 4B) and a support sleeve 140 (FIGS. 5A and 5B).
  • the insulative holder 130 comprises a first recess 134 that extends into the first end 132 and a second recess 138 that extends into a second end 136. Both the first recess 134 and the second recess 138 terminate within the body of the insulative holder 130 (e.g., both may have a floor). As depicted in FIG.4B, the diameter of the first recess 134 is greater than the diameter of the second recess 138. However, embodiments are contemplated in which the diameter of the first recess 134 is less than the diameter of the second recess 138 and embodiments are contemplated in which the diameters of the first recess 134 and the second recess 138 are equal.
  • the support sleeve 140 comprises a central opening 144 that extends from the first end 142 to the second end 146.
  • the diameter of the central opening 144 may be uniform from the first end 142 to the second end 146.
  • the diameter of the central opening 144 varies between the first end 142 and the second end 146.
  • the reaction crucible 110 extends into a first end 132 of the insulative holder 130 and the collection crucible 120 extends into a first end 142 of the support sleeve 140.
  • the reaction crucible 110 may be positioned within the first recess 134 of the insulative holder 130.
  • the collection crucible 120 may be positioned within the central opening 144 of the support sleeve 140.
  • a portion of the reaction crucible 110 extends beyond the first end 132 of the insulative holder 130 and a portion of the collection crucible 120 is extends beyond the first end 142 of the support sleeve 140, allowing the collar 105 to couple the reaction crucible 110 and the collection crucible 120 between the insulative holder 130 and the support sleeve 140.
  • the support sleeve 140 comprises graphite and the insulative holder 130 comprises a ceramic material, such as alumina, zirconia, fluorphlogopite mica in a borosilicate glass matrix, such as MACOR®, or the like.
  • the support sleeve 140 assists with the cooling of the collection crucible 120 and the insulative holder 130 both holds the reaction crucible 110 when heating (e.g., holds the reaction crucible 110 in the induction field of an induction heater) and operates as an insulator to help retain heat in the reaction crucible 110, improving heating efficiency of the reaction crucible 110.
  • the sublimation/distillation system 10 which may be used to reduce a metal oxide in the crucible assembly 100, is schematically depicted.
  • the sublimation/distillation system 10 includes a chamber 15 with gas, cooling, vacuum, power, and instrument feedthroughs.
  • the sublimation/distillation system 10 can generate an environment in the chamber 15 having a variety of conditions, such as high temperatures, low pressures, high levels of inert gas, and low partial pressures of select gases.
  • the sublimation/distillation system 10 includes a heating element 25.
  • the crucible assembly 100 may be positioned in the chamber 15 together with the heating element 25, such that the crucible assembly 100 may be heated in the chamber 15 using the heating element 25.
  • the heating element 25 is an induction heating element, such as an RF induction coil.
  • the crucible assembly 100 may be suspended or supported within the RF induction heating coil.
  • the heating element 25 comprises a resistance heating element, an infrared heating element, or any other known or yet to be developed heating element suitable for generating heat in a reduced pressure environment.
  • the chamber 15 may be fluidly coupled to a turbomolecular pump, which may be used to achieve high vacuum levels (i.e., low pressures) in the chamber 15.
  • the sublimation/distillation system 10 further comprises one or more temperature sensors 11 and one or more pressure sensors 12.
  • the one or more temperature sensors 11 are configured and positioned to monitor the temperature in the chamber 15, the temperature of the reaction crucible 110, and the temperature of the collection crucible 120.
  • the one or more pressure sensors 12 are configured and positioned to monitor the pressure in the chamber 15 and the pressure within the reaction crucible 110, and the pressure within the collection crucible 120.
  • Example temperature sensors 11 include thermocouples, resistive temperature detectors, thermopiles, thermistors, or any other known or yet to be developed temperature sensor.
  • Example pressure sensors 12 include ion gauges, or any other known or yet to be developed pressure sensor suitable for measuring pressure levels below 1 torr.
  • the method first comprises forming a powder mixture from an ytterbium oxide powder and a lanthanum powder.
  • the rare earth oxide particles of the rare earth oxide powder may have a small maximum cross-sectional dimension (e.g., a small diameter) as this may increase the distribution uniformity of the powder mixture and increase the packing density of the powder mixture, both of which improve the efficiency of the reduction process, allowing more rare earth metal to be recovered, increasing yield.
  • the rare earth oxide powder comprises rare earth oxide particles comprising an average maximum cross-sectional dimension of 8 ⁇ m or less, such as 7 ⁇ m or less, 6 ⁇ m or less, 5 ⁇ m or less, 4 ⁇ m or less, 3 ⁇ m or less, 4 ⁇ m or less, 2 ⁇ m or less, 1 ⁇ m or less, 0.5 ⁇ m or less, 0,1 ⁇ m or less, any range having any two of these values as endpoints, such as 0.5 ⁇ m to 5, 1 ⁇ m to 4 ⁇ m, and 1 ⁇ m to 3 ⁇ m, or any value in a range having any two of the values as endpoints.
  • the lanthanum powder comprises lanthanum particles comprising an average maximum cross-sectional dimension of 90 ⁇ m or less, such as 100 ⁇ m or less, such as 90 ⁇ m or less, 80 ⁇ m or less, 70 ⁇ m or less, 60 ⁇ m or less, 50 ⁇ m or less, or any range having any two of these values as endpoints or any value in a range having any two of the values as endpoints.
  • the rare earth oxide particles of the rare earth oxide powder have a particle size distribution in which most of the rare earth oxide particles have a small maximum cross-sectional dimension (e.g., a small diameter) as this may increase the distribution uniformity of the powder mixture and increase the packing density of the powder mixture, both of which improve the efficiency of the reduction process, allowing more rare earth metal to be recovered, increasing yield.
  • the rare earth oxide particles of the rare earth oxide powder comprise a particle size distribution in which 90% or more of the rare earth oxide particles comprise a maximum cross-sectional dimension of 10 ⁇ m or less.
  • the rare earth oxide particles of the rare earth oxide powder comprise a particle size distribution in which 95% or more of the rare earth oxide particles comprise a maximum cross-sectional dimension of 10 ⁇ m or less. In some embodiments, the rare earth oxide particles of the rare earth oxide powder comprise a particle size distribution in which 99% or more of the rare earth oxide particles comprise a maximum cross-sectional dimension of 10 ⁇ m or less. In some embodiments, the rare earth oxide particles of the rare earth oxide powder comprise a particle size distribution in which 90% or more of the rare earth oxide particles comprise a maximum cross-sectional dimension of 5 ⁇ m or less.
  • the rare earth oxide particles of the rare earth oxide powder comprise a particle size distribution in which 95% or more of the rare earth oxide particles comprise a maximum cross-sectional dimension of 5 ⁇ m or less. In some embodiments, the rare earth oxide particles of the rare earth oxide powder comprise a particle size distribution in which 99% or more of the rare earth oxide particles comprise a maximum cross-sectional dimension of 5 ⁇ m or less. [0068] Moreover, it may be advantageous of the rare earth oxide particles to have a high sphericity to improve packing efficiency of the powder mixture and improve the efficiency of the reduction process, allowing more rare earth metal to be recovered, increasing yield.
  • the ratio of the maximum cross-sectional dimension to the minimum cross- sectional dimension of 90% of more of the rare earth oxide particles of the rare earth oxide powder may be 2.5:1 or less, for example, 2.4:1 or less, 2.5:1 or less, 2.2:1 or less, 2.1:1 or less, 2:1 or less, 1.9:1 or less, 1.8:1 or less, 1.7:1 or less, 1.6:1 or less, 1.5:1 or less, 1.4:1 or less 1 ⁇ .3:1 or less 1 ⁇ .2:1 or less, 1.1:1 or less, or any range having any two of these values as endpoints or any value in a range having any two of the values as endpoints.
  • the ratio of the maximum cross-sectional dimension to the minimum cross-sectional dimension of 95% of more of the rare earth oxide particles of the rare earth oxide powder may be 2.5:1 or less, for example, 2.4:1 or less, 2.5:1 or less, 2.2:1 or less, 2.1:1 or less, 2:1 or less, 1.9:1 or less, 1.8:1 or less, 1.7:1 or less, 1.6:1 or less, 1.5:1 or less, 1.4:1 or less 1 ⁇ .3:1 or less ⁇ 1.2:1 or less, 1.1:1 or less, or any range having any two of these values as endpoints or any value in a range having any two of the values as endpoints.
  • the method may include a milling step, which can help achieve the desired sphericity.
  • the method may comprise milling the rare earth oxide powder, for example, jet milling the rare earth oxide powder, to increase a sphericity the rare earth oxide particles of the rare earth oxide powder. This may also increase a volume to surface area ratio of the rare earth oxide particles. It should be understood that any suitable milling technique may be used.
  • the powder mixture is a homogeneous mixture of rare earth oxide powder (e.g., ytterbium oxide powder or gadolinium powder) and lanthanum powder.
  • the rare earth oxide powder and lanthanum powder may be mixed until the powder mixture is homogenous grey.
  • the powder mixture comprises rare earth oxide powder and a range of from 15% to 250% excess (by mole) lanthanum metal powder, for example, from 25% to 200% excess (by mole), from 50% to 200% excess (by mole), from 75% to 200% excess (by mole), from 90% to 200% excess (by mole), from 100% to 200% excess (by mole) ⁇ from 125% to 200% excess (by mole), from 150% to 200% excess (by mole), from 175% to 200% excess (by mole), any range having any two of these values as endpoints, or any value in a range having any two of these values as endpoints.
  • the powder mixture may be positioned in the reaction region 102 of the crucible assembly 100, for example, in the reaction crucible 110.
  • the method further comprises agitating the powder mixture to increase a distribution uniformity of the rare earth oxide powder and the lanthanum powder in the powder mixture. Agitating the powder mixture may comprising mixing, shaking, or the like. The agitating step may occur while the powder mixture is in the reaction crucible 110. In some embodiments, the powder mixture is a homogeneous mixture after agitating the powder mixture.
  • the method may comprise packing the powder mixture to increase a density of the powder mixture in the reaction crucible 110, for example, by stamping the powder mixture to press the particles of the power mixture together.
  • the crucible assembly 100 housing the powder mixture may be placed in the chamber 15 of the sublimation/distillation system 10, which forms a reduced pressure environment.
  • the method further comprises heating the powder mixture by applying heat to the reaction crucible 110 using the heating element 25, and thus applying heat to the powder mixture.
  • Heating the powder mixture reduces the ytterbium oxide powder into an ytterbium metal that collects on the collection region 104 of the crucible assembly 100, for example, in the collection crucible 120.
  • ytterbium metal may sublimate from the powder mixture, separating from the ytterbium oxide, lanthanum, and lanthanum oxide, and collecting in the collection crucible 120.
  • lanthanum is retained in the reaction region 102 of the crucible assembly 100, for example, in the reaction crucible 110, as heat is applied to the powder mixture.
  • the ytterbium metal is separated from both the oxygen of the ytterbium oxide and from the lanthanum of the powder mixture.
  • the powder mixture is heated to a temperature less than 900° C, for example, in a range of from 200° C to less than 900° C or 300° C to 875° C, for example, a temperature of 300° C, 350° C, 400° C, 450° C, 500° C, 550° C, 600° C, 650° C, 700° C, 750° C, 800° C, 825° C, 850° C, 875° C, 890° C, or value in a range having any two of these values as endpoints.
  • the collection region 104 of the crucible assembly 100 for example, the collection crucible 120, may be cooled while the powder mixture is heated.
  • the sublimation/distillation system 10 includes a cold finger, which may be actively cooled using one or more cooling fluid lines, and the cold finger extends into the second end 146 of the support sleeve 140 to cool the collection crucible 120.
  • the cold finger may directly contact the collection crucible 120.
  • a stepper may be coupled to the second end 136 of the insulative holder 130 when heating the powder mixture.
  • the stepper is configured to translate the crucible assembly 100 within the reduced pressure environment (e.g., within the chamber 15 of the sublimation/distillation system 10) facilitating selective positioning of the crucible assembly 100, for example, with respect to the heating element 25.
  • the method further includes monitoring a pressure in the reduced pressure environment using a pressure sensor and reducing the heat applied by the heating element 25 to the powder mixture when the pressure in the reduced pressure environment is above a threshold pressure.
  • the threshold pressure may be in a range of from 1x10 -8 torr to 0.1 torr, for example, from 1x10 -7 torr to 1x10 -2 torr, from 1x10 -6 torr to 1x10 -2 torr, from 1x10 -6 torr to 1x10 -3 torr, from 1x10 -6 torr to 1x10 -4 torr, from 1x10 -6 torr to 1x10 -5 torr, from 1x10 -6 torr to 5x10 -5 torr, such as 1x10 -8 torr, 5x10 -8 torr, 1x10 -7 torr, 5x10 -7 torr, 1x10 -6 torr, 5x10 -6 torr, 1x10 -5 torr, 5x10 -5 torr, 1x10 -4 torr, 5x10 -4 torr, 1x10 -3 torr, , 5x10 -3 torr
  • the method when the pressure in the reduced pressure environment is above the threshold pressure, the method comprises halting application of heat by the heating element to the powder mixture, reducing the temperature of the powder mixture.
  • the method may also comprise reducing the pressure, for example, using one or more vacuum pumps, such as turbomolecular pumps fluidly coupled to the chamber 15.
  • the method further comprises resuming the application of heat from the heating element 25 to the powder mixture.
  • Maintaining the variables of temperature and pressure within desired ranges allows the underlying chemical processes to be better understood and controlled, facilitating increases in process scale (e.g., increases in the volume of rare earth oxides reduced in the process). Moreover, reducing the temperature when the pressure in the reduced pressure environment both improves the purity of the collected rare earth metal and minimizes loss of the rare earth metal. For example, an increase in pressure in the crucible assembly 100 may occur due to gaseous rare earth metal (such as gaseous ytterbium metal) escaping the crucible assembly 100, lowering the yield.
  • gaseous rare earth metal such as gaseous ytterbium metal
  • the reduction process is complete when the pressure is at or below the threshold pressure, the heating element continues to apply heat to the crucible assembly, and the temperature of the reaction region 102 of the crucible assembly 100 (e.g., the reaction crucible 110) is greater than 1000o C.
  • these parameters may be achieved if, for example, all the lanthanum has reacted, leaving no reductant for the reaction.
  • the method may include removing the application of heat to the reaction region 102 of the crucible assembly 100 (e.g., the reaction crucible 110), allowing the temperature to reduce and the ytterbium metal to be collected. [0076] After separating ytterbium metal from the powder mixture, the method may next comprise collecting the ytterbium metal.
  • One way to collect the ytterbium metal is by performing an additional sublimation step to transfer the ytterbium metal from the collection region 104 of the crucible assembly 100 (e.g., from the collection crucible 120) to a collection substrate comprising a material and shape that facilitates removal and collection of the ytterbium metal.
  • a collection substrate is a flat quartz plate.
  • Other example collection substrates include molybdenum, titanium, and tantalum substrates, for example, a flat molybdenum plate, a flat titanium plate, or a flat tantalum plate.
  • This method step may comprise orienting a collection substrate to face the collection region 104 of the crucible assembly 100, which is now holding the ytterbium metal (e.g., orienting the collection substrate to face an open end of the collection crucible 120) and sublimating the ytterbium metal in an environment at a temperature in a range of from 400o C to 3000o C to transfer the ytterbium metal from the collection region 104 of the crucible assembly 100 to a collection surface of the collection substrate. The ytterbium metal may then be removed from the collection substrate for further processing.
  • the ytterbium metal e.g., orienting the collection substrate to face an open end of the collection crucible 120
  • the method may next comprise irradiating the ytterbium metal with neutrons to form an irradiated solid composition comprising ytterbium and lutetium.
  • This irradiation step may occur using a nuclear reactor, a particle accelerator, or any other known or yet to be developed source of neutrons.
  • lutetium may be separated and purified from the irradiated solid composition, for example, using the methods described in PCT/US2020/061332 and PCT/US2021/025439, both of which are incorporated herein by reference in their entirety.
  • ytterbium may be sublimated from the irradiated solid composition in an environment at a temperature in a range of from 400o C to 3000o C to leave a lutetium composition comprising a higher weight percentage of lutetium than was present in the irradiated solid composition.
  • the environment may be a reduced pressure environment and/or an inert environment.
  • the temperature in the environment is less than 700o C.
  • the vaporized fraction of the irradiated solid composition can then be recovered downstream after the vapor is condensed. In this case, the ytterbium is vaporized (and it may be collected downstream for later use) leaving behind a material that is enriched in lutetium.
  • ytterbium that is collected is available for recycling (e.g., for another round of neutron irradiation) to produce further irradiated solid composition and to thereafter produce further lutetium in subsequent runs of the process.
  • the ytterbium that is sublimated/distilled from the solid composition may be recycled as additional target material for irradiation and re-use in a subsequent separation process.
  • the sublimation/distillation process of separating ytterbium from the irradiated solid composition yields a sample (“the lutetium composition”) that is enriched in lutetium as compared to the irradiated solid composition that enters the process.
  • the yields and purity may be measured in a number of ways. For example, in some embodiments, the process yields an ytterbium mass reduction of the solid composition from 1000:1 to 10,000:1. In other words, after the lutetium yielding sublimation is completed, there is 1000 to 10,000 times less ytterbium in the sample than prior to the process (i.e., than was present in the solid composition).
  • the lutetium composition that is recovered there may, in some embodiments, be from 1 wt% to 90 wt% of ytterbium relative to total remaining mass that will then be separated as described below in a chromatographic process.
  • the ytterbium that is collected from the lutetium yielding sublimation is collected in an amount that is from 90 wt% to 99.999 wt% of the ytterbium present in the solid composition.
  • the purification steps are also conducted to remove other trace metals and contaminants.
  • the lutetium yielding sublimation includes subjecting a sample comprising Yb-176 and Lu-177 to sublimation, distillation, or a combination thereof to remove at least a portion of the Yb-176 from the sample and form a Lu-177-enriched sample.
  • the temperature for the lutetium yielding sublimation may be in a range of from 400o C to 3000o C, for example, from 450o C to 1500o C, from 450o C to 1200o C, from 450o C to 1000o C, from 400o C to 1000o C, from 400o C to 900o C, from 400o C to 800o C, from 450o C to 700o C, from 400o C to less than 700o C, from 400o C to 695o C, from 450o C to 690o C, from 450o C to 685o C, from 450o C to 680o C, from 450o C to 675o C, from 450o C to 670o C, from 450o C to 665o C, from 450o C to 660o C, from 450o C to 655o C, from 450o C to 650o C, from 450o C to 645o C, from 450o C to
  • the temperature for sublimation and/or distillation may be 400o C, 425o C, 450o C, 470o C, 475o C, 500o C, 525o C, 550o C, 575o C, 600o C, 625o C, 640o C, 650o C, 655o C, 660o C, 665o C, 670o C, 675o C, 680o C, 685o C, 690o C, 695o C, 698o C, 700o C, 725o C, 750o C, 775o C, 800o C, 850o C, 900o C, 950o C, 1000o C, 1100o C, 1200o C, 1300o C, 1400o C, 1500o C, 1600o C, 1700o C, 1800o C, 1900o C, 2000o C, 2100o C, 2200o C, 2300o C, 2400o C, 2500o C, 2600o C
  • the pressure of the environment at any of the temperatures and temperature ranges described above may be in a range of from 2000 torr to 1x10 -8 , from 1520 torr to 1x10 -8 torr, from 1000 torr to 1x10 -8 torr, from 760 torr to 1x10 -8 torr, from 700 torr to 1x10 -8 torr, from 500 torr to 1x10 -8 torr, from 250 torr to 1x10 -7 torr, from 100 torr to 1x10 -6 torr, from 1 torr to 1x10 -6 torr, from 1x10 -1 torr to 1x10 -6 torr, 1x10 -3 or less, 1x10 -5 torr or less, 1x10 -6 torr or less, from 2000 torr to 1x10 -1 torr, from 1520 torr to 1 torr, from 1000 torr to 1 torr, from
  • temperature ramp rates over a period of 10 minutes to 2 hours may be employed to ensure no blistering or uneven heating of the irradiated solid composition.
  • a vacuum is established to degas the sample. This vacuum may be about 1 x 10 -6 torr for approximately 5 minutes to 1 hour.
  • the time period required for the lutetium yielding sublimation may vary widely and is dependent upon the amount of material in the irradiated solid composition, the temperature, and the pressure. It may vary from 1 second to 1 week. In some embodiments, it is a rate of sublimation or distillation that is pertinent to the question of time.
  • Yb may be at a rate of from 10 min/g to 100 min/g of solid composition, or from 20 min/g to 60 min/g of solid composition. In one embodiment, the rate may be 40 min/g of solid composition.
  • a purification of greater than 1000:1 reduction i.e. a 1000 times reduction in the amount of Yb present
  • higher reductions in Yb may be required to meet purity requirements for some pharmaceutical products. Accordingly, additional purification may be conducted prior to use in pharmaceutical applications.
  • Such purification may be obtained through the use of chelators and/or chromatographic separation.
  • Any of the above lutetium compositions or lutetium-enriched samples, as described herein, may be subjected to chromatographic separation to further enrich the lutetium in the composition or sample.
  • Such chromatographic separations may include column chromatography, plate chromatography, thin cell chromatography, or high-performance liquid chromatography.
  • Illustrative processes for purification of lutetium may be as described in U.S. 7,244,403 and 9,816,156, both of which are incorporated herein by reference in their entirety. However, it should be understood that other chromatographic separation techniques may be used to further enrich the lutetium separated using the techniques described herein.
  • a process may include dissolving in an acid the lutetium and ytterbium composition that remains after sublimation and applying the resultant solution to a chromatographic column or plate.
  • This may include plate chromatographic materials, chromatographic columns, HPLC chromatographic columns, ion exchange columns, and the like.
  • Coupled means the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent or fixed) or moveable (e.g., removable or releasable).
  • Such joining may be achieved with the two members coupled directly to each other, with the two members coupled to each other using a separate intervening member and any additional intermediate members coupled with one another, or with the two members coupled to each other using an intervening member that is integrally formed as a single unitary body with one of the two members.
  • additional term e.g., directly coupled
  • the generic definition of “coupled” provided above is modified by the plain language meaning of the additional term (e.g., “directly coupled” means the joining of two members without any separate intervening member), resulting in a narrower definition than the generic definition of “coupled” provided above.
  • Such coupling may be mechanical, electrical, optical, or fluidic.
  • references herein to the positions of elements are merely used to describe the orientation of various elements in the FIGURES. It should be noted that the orientation of various elements may differ according to other exemplary embodiments, and that such variations are intended to be encompassed by the present disclosure.
  • the figures and description may illustrate a specific order of method steps, the order of such steps may differ from what is depicted and described, unless specified differently above. Also, two or more steps may be performed concurrently or with partial concurrence, unless specified differently above. Such variation may depend, for example, on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure.

Abstract

Le procédé selon la présente invention comprend la formation d'un mélange pulvérulent à partir d'une poudre d'oxyde de terre rare et d'une poudre de lanthane, le chauffage du mélange de poudre dans un ensemble creuset positionné dans un environnement à pression réduite, le chauffage du mélange de poudre comprenant l'application de chaleur à l'aide d'un élément chauffant et le chauffage du mélange de poudre réduisant la poudre d'oxyde de terre rare en un métal des terres rares qui s'accumule sur une région de collecte de l'ensemble creuset. Le procédé comprend également la surveillance d'une pression dans l'environnement à pression réduite à l'aide d'un capteur de pression et la réduction de la chaleur appliquée par l'élément chauffant au mélange de poudre lorsque la pression dans l'environnement à pression réduite est supérieure à une pression seuil.
PCT/US2023/025424 2022-06-15 2023-06-15 Procédés et systèmes de réduction d'oxydes de métaux des terres rares WO2023244732A1 (fr)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6309441B1 (en) * 1996-10-08 2001-10-30 General Electric Company Reduction-melting process to form rare earth-transition metal alloys and the alloys
US20150159238A1 (en) * 2013-03-04 2015-06-11 Charles Clayton WYCUFF Dross processing system
US20170306523A1 (en) * 2016-04-25 2017-10-26 Innovative Advanced Materials, Inc. Effusion cells, deposition systems including effusion cells, and related methods
US20210025027A1 (en) * 2019-07-26 2021-01-28 W. Davis Lee Rare earth oxide to rare earth extraction apparatus and method of use thereof
US20210115548A1 (en) * 2018-01-31 2021-04-22 Saint-Gobain Centre De Rechercherches D'etudes Europeen Powder for coating an etch chamber
WO2021202914A1 (fr) * 2020-04-02 2021-10-07 SHINE Medical Technologies, LLC Séparation d'éléments de terres rares

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6309441B1 (en) * 1996-10-08 2001-10-30 General Electric Company Reduction-melting process to form rare earth-transition metal alloys and the alloys
US20150159238A1 (en) * 2013-03-04 2015-06-11 Charles Clayton WYCUFF Dross processing system
US20170306523A1 (en) * 2016-04-25 2017-10-26 Innovative Advanced Materials, Inc. Effusion cells, deposition systems including effusion cells, and related methods
US20210115548A1 (en) * 2018-01-31 2021-04-22 Saint-Gobain Centre De Rechercherches D'etudes Europeen Powder for coating an etch chamber
US20210025027A1 (en) * 2019-07-26 2021-01-28 W. Davis Lee Rare earth oxide to rare earth extraction apparatus and method of use thereof
WO2021202914A1 (fr) * 2020-04-02 2021-10-07 SHINE Medical Technologies, LLC Séparation d'éléments de terres rares

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