Process for the purification of metals in liquid medium at low temperatures

Abstract

According to one aspect of the present disclosure, a method of producing purified silicon comprises providing an alkali or alkaline earth metal and a metallic or aminated halide salt of silicon; combining the alkali or alkaline earth metal and metallic or aminated halide salt of silicon in a liquid medium to form a precipitate; combining the precipitate with sulfuric acid or another acid to form a byproduct and silicon; and recovering the purified silicon. In some embodiments, the liquid medium is an amine or ammonia. In some embodiments, the alkali or alkaline earth metal and metallic or aminated halide salt of silicon are combined at a low temperature such that the amine or ammonia are in a liquid phase.

Description

ATTY DOCKET NO. SAUTER-002AWOPROCESS FOR THE PURIFICATION OF METALS IN LIQUID MEDIUM AT LOW TEMPERATURESCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit under 35 U.S.C. §119 of U.S. Provisional Patent Application No. 63 / 704,748 filed on October 8, 2024, which is hereby incorporated by reference herein in its entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

[0002] N / ABACKGROUND

[0003] The electronics industry has an increasing demand for semiconductor and solar grade polycrystalline silicon, driven in part by the ever growing need for complex semiconductors in many commonly used electronics and the rise of photovoltaic cells. Polycrystalline silicon is a material consisting of several small silicon crystals. “Semiconductor grade” refers to a high quality polycrystalline silicon with exceptional purity and minimal contamination. Semiconductor grade polycrystalline silicon is converted to single crystal silicon and is used to manufacture most silicon based microelectronic devices. Solar grade polycrystalline silicon is converted to single crystal silicon and is used to manufacture most photovoltaic cells.

[0004] One process for producing such polycrystalline silicon is referred to as the Siemens process. The Siemens process is a chemical vapor deposition based process, which involves the distillation of volatile silicon compounds and their decomposition on to silicon. The Siemens process converts metallurgical-grade silicon to SiHCL or SiHs and then to silicon in a reactor, removing the dopant and transition metal impurities. The Siemens process is typically run at a high temperature of 1110°C. This process is expensive due to the equipment, chemicals, and power consumption involved. Alternative processes have beenATTY DOCKET NO. SAUTER-002AWO suggested, but often require similar high temperatures and often involve hazardous conditions.SUMMARY OF DISCLOSED EMBODIMENTS

[0005] Disclosed herein is a method for producing a purified metal, especially silicon, by combining a metallic or aminated halide salt of the desired metal with an alkali or alkaline earth metal in a liquid medium, resulting in the desired metal deposited in a solid precipitate. The metal is subsequently recovered and washed to separate the purified metal from the byproducts. The liquid medium can be an amine or ammonia. The method is performed at a substantially low temperature (i.e., below the boiling point of the amine or ammonia) depending on the pressure, such that the amine or ammonia is in a liquid phase. The disclosed method advantageously utilizes a liquid at a lower temperature, enabling decreased constructions costs and operating costs, lower power consumption, and safer operating conditions.

[0006] According to one aspect of the present disclosure, a method of producing purified silicon comprises: providing an alkali or alkaline earth metal and a metallic or aminated halide salt of silicon; combining the alkali or alkaline earth metal and metallic or aminated halide salt of silicon in a liquid medium to form a precipitate; combining the precipitate with sulfuric acid or another acid to form a byproduct and silicon; and recovering the purified silicon.

[0007] In some embodiments, the liquid medium is an amine or ammonia. In some embodiments, the liquid medium is an amine or ammonia and the alkali or alkaline earth metal and metallic or aminated halide salt of silicon are combined at a low temperature such that the amine or ammonia are in a liquid phase. In some embodiments, the liquid medium is an amine or ammonia and the alkali or alkaline earth metal and metallic or aminated halide salt of silicon are combined at a low temperature such that the amine or ammonia are in a liquid phase, wherein theATTY DOCKET NO. SAUTER-002AWO alkali or alkaline earth metal and metallic or aminated halide salt of silicon are combined at a temperature of about 115°C and a pressure of about 100 atm.

[0008] In some embodiments, the alkali or alkaline earth metal is sodium. In some embodiments, the metallic or aminated halide salt of silicon is a alkali metal silicate, an alkaline earth metal silicate, a transition metal silicate, or an aluminosilicate. In some embodiments, the metallic or aminated halide salt of silicon is sodium hexafluorosilicate or sodium fluorosilicate. In some embodiments, the method further comprises grinding the alkali or alkaline earth metal and the metallic or aminated halide salt of silicon under nitrogen atmosphere, wherein the liquid medium is anhydrous liquid ammonia or an amine. In some embodiments, the method further comprises dissolving the alkali or alkaline earth metal in anhydrous liquid ammonia to form about a three normal or greater solution then adding the metallic or aminated halide salt of silicon, wherein recovering the purified silicon further comprises washing the silicon with water to remove the byproducts. In some embodiments, the method further comprises providing an alkali or alkaline earth metal dispersion and washing an alkali or alkaline earth metal from the metal dispersion with petroleum ether to provide the alkali or alkaline earth metal. In some embodiments, the method further comprises mixing the alkali or alkaline earth metal, metallic or aminated halide salt of silicon, and liquid medium with a stirring device.

[0009] According to another aspect of the present disclosure, a method of producing a purified metal comprises: providing an alkali or alkaline earth metal and a metallic or aminated halide salt of the purified metal; combining the alkali or alkaline earth metal and the metallic or aminated halide salt of the purified metal in a liquid amine or liquid ammonia to form a precipitate; combining the precipitate with sulfuric acid or another acid to form a byproduct and the purified metal; and recovering the purified metal.

[0010] In some embodiments, the purified metal is a metal of an element selected from the group of elements from group II, III, IV, V, or VI of the periodic table of the elements. In some embodiments, the purified metal is a metal of an element selected from the group of elements from group II, III, IV, V, or VI of theATTY DOCKET NO. SAUTER-002AWO periodic table of the elements, wherein the purified metal is a metal of an element selected from the group of elements comprising beryllium, boron, scandium, arsenic, yttrium, titanium, zirconium, hafnium, thorium, vanadium, niobium, tantalum, chromium, germanium, molybdenum, gallium, selenium, and tungsten. In some embodiments, the purified metal is a metal of an element selected from the group of elements from group II, III, IV, V, or VI of the periodic table of the elements, wherein the purified metal is a metal of an element selected from group II or group III.

[0011] In some embodiments, the method further comprises combining the alkali or alkaline earth metal and the metallic or aminated halide salt of the purified metal at a low temperature such that the amine or ammonia are in a liquid phase. In some embodiments, the method further comprises combining the alkali or alkaline earth metal and metallic or aminated halide salt of the purified metal at a temperature of about 115°C and a pressure of about 100 atm. In some embodiments, the method further comprises grinding the alkali or alkaline earth metal and metallic or aminated halide salt of the purified metal under nitrogen atmosphere, wherein the liquid amine or liquid ammonia is anhydrous liquid ammonia. In some embodiments, wherein the method further comprises dissolving the alkali or alkaline earth metal in anhydrous liquid ammonia to form about a three normal or greater solution then adding the metallic or aminated halide salt of the purified metal, wherein recovering the purified metal further comprises washing the purified metal with water to remove the byproducts. In some embodiments, the method further comprises mixing the alkali or alkaline earth metal, metallic or aminated halide salt of the purified metal, and liquid amine or liquid ammonia with a stirring device.DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0012] The manner and process of making and using the disclosed embodiments may be appreciated by reference to the figures of the accompanying drawings. It should be appreciated that the components and structures illustrated in the figures are not necessarily to scale, emphasis instead being placed uponATTY DOCKET NO. SAUTER-002AWO illustrating the principles of the concepts described herein. Like reference numerals designate corresponding parts throughout the different views. Furthermore, embodiments are illustrated by way of example and not limitation in the figures, in which:

[0013] FIG. 1 is a flowchart of an example of a method for producing purified silicon;

[0014] FIG. 2 is a flowchart of an example of a method for producing a purified metal;

[0015] FIG. 3 is an x-ray diffraction (XRD) scan of purified silicon resulting from the disclosed method; and

[0016] FIG. 4 is an XRD scan of silicon resulting from prior art methods.DETAILED DESCRI PTION

[0017] Concepts herein are directed towards a method for producing purified metals. One aspect is a method of producing purified silicon, by providing and combining an alkali or alkaline earth metal and a metallic or aminated halide salt of silicon in a liquid medium to form a precipitate. The precipitate is combined with sulfuric acid or another acid to form a byproduct and silicon. The silicon is subsequently recovered, by washing the silicon to separate the purified silicon from the byproducts. The liquid medium is an amine or ammonia, enabling the method to be run at a low temperature (i.e., below the boiling point of the solvent - the amine or ammonia), depending on the pressure. Performing the method in the presence of liquid ammonia or an amine retains the reducing power of the metal, while enabling the method to proceed at much lower temperatures than previously known.

[0018] Referring to FIG. 1 , an example of a method to provide purified silicon is method 100. In a first step 102, an alkali or alkaline earth metal and a metallic or aminated halide salt of silicon are provided. The alkali or alkaline earth metal can be any metal from group I or group II of the periodic table, for example the alkali or alkaline earth metal can be sodium. The metallic or aminated halide salt of silicon can be sodium fluorosilicate or sodium hexafluorosilicate. The metallic orATTY DOCKET NO. SAUTER-002AWO aminated halide salt of silicon can be a alkali metal silicate (e.g., sodium silicate), an alkaline earth metal silicate (e.g., calcium silicate), a transition metal silicate (e.g., iron silicide), or an aluminosilicate (e.g., aluminum silicate). The metallic or aminated halide salt of silicon can be a silicon halide (e.g., SiX4, wherein X = Cl, Br, I) or ammonium hexafluorosilicate.

[0019] The alkali or alkaline earth metal can be provided by washing an alkali or alkaline earth metal from an alkali or alkaline earth metal dispersion with petroleum ether or another appropriate solvent. For example, finely ground sodium metal with 99+% purity can be obtained from a sodium dispersion (e.g., a sodium dispersion with 40% sodium in mineral oil) by washing the sodium metal with petroleum ether to remove the mineral oil. In another embodiment, the sodium may be provided in a container with argon or another appropriate gas (i.e., a noble gas), in which case washing the sodium may not be necessary.

[0020] In a second step 104, the alkali or alkaline earth metal and metallic or aminated halide salt of silicon are combined in a liquid medium to form a precipitate. The desired metal to be purified, here silicon, is disposed in the solid precipitate. The liquid medium is an amine or ammonia, for example a liquid amine or a substantially anhydrous liquid ammonia medium. The amine can be a primary amine (e.g. methylamine, CH3NH2), a secondary amine (e.g., dimethylamine, (CH3)2NH), or a tertiary amine (e.g., trimethylamine, (CH3)3N).

[0021] The alkali or alkaline earth metal and metallic or aminated halide salt of silicon can be combined at a low temperature, such that the amine or ammonia are in a liquid phase. As used herein, “low temperature” refers to a temperature below the boiling point of the liquid medium. For example, ammonia at normal atmospheric pressure (1 atm) boils at -33.3°C, so liquid ammonia at low temperature and at normal atmospheric pressure (1 atm) would be below about - 33.3°C (+ / - 1°C). In an example embodiment, when the liquid medium is ammonia, when the alkali or alkaline earth metal, the metallic or aminated halide salt of silicon, and ammonia are combined at normal atmospheric pressure (1 atm), the temperature range can be at or below about 0°C (+ / - 1 °C) to about - 33.3°C (+ / - 1°C); -100°C (+ / - 5°C) to about -33.3°C (+ / - 1°C); -50°C (+ / - 5°C) toATTY DOCKET NO. SAUTER-002AWO about -33.3°C (+ / - 1 °C); or -40°C (+ / - 5°C) to about -33.3°C (+ / - 1 °C). For example, at a pressure of 100 atm, the temperature may be at or below about 0°C (+ / - 1 °C) to at or above about 200 °C (+ / - 10°C); at or below about 0°C (+ / - 1 °C) to at or above about 115°C (+ / - 10°C); and at or below about 0°C (+ / - 1 °C) to at or above about 100°C (+ / - 10°C).

[0022] For trimethylamine, the boiling point at normal atmospheric pressure (1 atm) is 3.5°C, so trimethylamine at low temperature and at normal atmospheric pressure (1 atm) would be below about 3.5°C (+ / - 1°C ). In an example embodiment, when the liquid medium is trimethylamine, when the alkali or alkaline earth metal, the metallic or aminated halide salt of silicon, and trimethylamine are combined at normal atmospheric pressure (1 atm), the temperature range can be at or below about -100°C (+ / - 1 °C) to about 3.5°C (+ / - 1 °C); -50°C (+ / - 5°C) to about 3.5°C (+ / - 1°C); -25°C (+ / - 5°C) to about 3.5°C (+ / - 1°C); -10°C (+ / - 5°C) to about 3.5°C (+ / - 1 °C); or 0°C (+ / - 5°C) to about 3.5°C (+ / - 1 °C).

[0023] In an example embodiment, the alkali or alkaline earth metal and metallic or aminated halide salt of silicon can be combined at a temperature where the amine or ammonia are in a liquid phase, but at a pressure above normal atmospheric pressure (1 atm) or higher (200 atm or above). For example, the method can be performed at a pressure of about 1 atm (+ / - 0.5 atm) to about 200 atm (+ / - 10 atm); of about 1 atm (+ / - 0.5 atm) to about 25 atm (+ / - 10 atm); of about 25 atm (+ / - 10 atm) to about 50 atm (+ / - 10 atm); or of about 50 atm (+ / - 10 atm) to about 200 atm (+ / - 10 atm).

[0024] Further, the alkali or alkaline earth metal, metallic or aminated halide salt of silicon, and liquid medium can be combined at a low temperature or the entire method can be performed at a low temperature. Following, the entire method can also be performed above a normal atmospheric pressure (1 atm).

[0025] In an example embodiment, the alkali or alkaline earth metal, metallic or aminated halide salt of silicon, and ammonia can be combined at a temperature of about 115°C (+ / - 1 °C) and a pressure of about 100 atm (+ / - 10 atm), which is below the boiling point of ammonia of 125 °C at 100 atm. Single crystals can be made using the disclosed method at a temperature of 115°C and a pressure ofATTY DOCKET NO. SAUTER-002AWO100 atm. This is analogous to hydrothermal crystallization of materials using ammonia or an amine instead of water, utilizing similar techniques but taking advantage of the low critical temperature (i.e., the low boiling point) of ammonia.

[0026] The method can take place in a clean room or an otherwise sterile system. The method can be performed in a sealed reaction container suitable for containing the appropriate liquid medium and conducting the particular method, so as to preclude other reactants or contaminants from entering the system or container. The container may be equipped with a means for bringing the reactants into contact with each other such as a stirring device or other mixing device, such as a magnetic stirring rod, magnetic stirring bar, mixer, or shaker.

[0027] In an example embodiment, the mixture of alkali or alkaline earth metal and metallic or aminated halide salt of silicon can be prepared by grinding the appropriate molar ratio with a mortar and pestle in a dry box under nitrogen atmosphere. In an example embodiment, the alkali or alkaline earth metal and metallic or aminated halide salt of silicon is wet with about ten times its weight of anhydrous liquid ammonia. In an alternative example embodiment, the alkali or alkaline earth metal can be dissolved in the anhydrous liquid ammonia to achieve about a three normal solution or greater (a higher than normal solution, i.e., concentration) and then the metallic or aminated halide salt of silicon is added. The alkali or alkaline earth metal, metallic or aminated halide salt of silicon, and ammonia can be mixed with a stirring device.

[0028] In a third step 106, the precipitate is combined with sulfuric acid or another acid to form a byproduct and silicon. The precipitate can be washed or otherwise reacted with sulfuric acid. Another acid can be hydrochloric acid, nitric acid, or acetic acid. In an example embodiment, the acid is concentrated, the ammonia is evaporated off, and the byproduct is sodium sulfate.

[0029] In a fourth step 108, the purified silicon is recovered, which can include washing the silicon with water or distilled water to remove the byproducts.

[0030] More broadly, the disclosed method can be used to produce a purified metal selected from groups II, III, IV, V, or VI of the periodic table of the elements. In some embodiments, the purified metal can be a group Illa or II lb metal. TheATTY DOCKET NO. SAUTER-002AWO purified metal can be a metal of an element selected from the group of elements, such as beryllium, boron, scandium, arsenic, yttrium, silicon (i.e. , using the method illustratively elaborated upon herein in connection with FIG. 1), titanium, zirconium, hafnium, thorium, vanadium, niobium, tantalum, chromium, germanium, molybdenum, gallium, selenium, and tungsten. The disclosed method for producing a purified metal selected from these chemical groups is similar to the method for producing purified silicon.

[0031] Referring to FIG. 2, an example of a method to provide a purified metal is method 200. In a first step 202, provide an alkali or alkaline earth metal and a metallic or aminated halide salt of the purified metal.

[0032] In a second step 204, combine the alkali or alkaline earth metal and the metallic or aminated halide salt of the purified metal in liquid amine or liquid ammonia to form a precipitate. The alkali or alkaline earth metal and metallic or aminated halide salt of the purified metal can be combined at a low temperature such that the amine or ammonia are in a liquid phase.

[0033] In a third step 206, combine the precipitate with sulfuric acid or another acid to form a byproduct and the purified metal. Another acid can be hydrochloric acid, nitric acid, or acetic acid. In a fourth step 208, the purified metal is recovered.

[0034] Provided below are several example methods of providing a purified metal, specifically silicon.

[0035] EXAMPLE 1

[0036] For example, consider the following method of producing purified silicon: first, grind metallic sodium and sodium fluorosilicate. Next, combine the metallic sodium and sodium fluorosilicate in liquid ammonia, resulting in a precipitate, including: sodium fluoride and silicon. In an alternative example embodiment, the alkali or alkaline earth metal can be dissolved in the anhydrous liquid ammonia to achieve about a three normal solution (a higher normal solution, i.e., concentration) and then the metallic or aminated halide salt of silicon is added. The reaction can be represented by the following equation (1):ATTY DOCKET NO. SAUTER-002AWONH34Na + Na2SiF6- > 6NaF +Si (1)

[0037] Next, wash the precipitate with sulfuric acid. The ammonia evaporates off. The reaction can be represented by the following equation (2):Si + NaF +Na2SiFe + H2SO4 - > SiF4(g) + Na2SO4 + Si (2)

[0038] Next, recover the purified silicon. The silicon tetrafluoride forms a gas, which bubbles off and can be recycled. The sodium sulphate is soluble in water and may then be washed out. The reaction can be represented by the following equation (3):Solution (3)

[0039] EXAMPLE 2

[0040] For example, consider the following representative equation (4) and method of producing purified silicon:NH3

[0041] First, to provide the sodium, finely ground sodium metal with 99+% purity is obtained from a sodium dispersion (40% sodium in mineral oil), by washing the ground metal with petroleum ether to remove the mineral oil. Next, sodium metal and sodium hexafluorosilicate is mixed by grinding with a mortar and pestle in a dry box under nitrogen atmosphere. Next, the mixture is wet with about ten times its weight of anhydrous liquid ammonia. In an alternative example embodiment, the alkali or alkaline earth metal can be dissolved in the anhydrous liquid ammonia to achieve about a three normal solution or greater (i.e., a higher than normal solution, i.e., concentration) and then the metallic or aminated halide salt of silicon is added. The sodium metal, sodium hexafluorosilicate, and anhydrous liquid ammonia are mixed and the precipitate dried immediatelyATTY DOCKET NO. SAUTER-002AWO afterwards. The mixture is then reacted with an excess of sulfuric acid. Following, the dried brown powder (i.e., the silicon and byproduct) is reacted with concentrated sulfuric acid, followed by repeated washing with distilled water.

[0042] FIG. 3 is an XRD scan 300 of purified silicon provided by the disclosed method, with distinct peaks at the (311) plane 302, (220) plane 304, and (111) plane 306 corresponding to silicon crystallographic planes. The XRD scan 300 has notably sharp peaks at each plane 302, 304, 306, indicating the sample of purified silicon resulting from the disclosed method is notably pure.

[0043] In contrast, FIG. 4 is an XRD scan 400 of silicon resulting from the prior art methods, with peaks at the (311 ) plane 402, (220) plane 404, and (111) plane 406 corresponding to silicon crystallographic planes. Unlike the sharp peaks at each plane 302, 304, 306 in the XRD scan 300, the peaks corresponding to the planes 402, 404, 406 are not as sharp, indicating the prior art sample is not as pure.The disclosed method of purifying metals produces a notably pure sample, while utilizing a lower temperature, providing an alternative method for purifying metals with decreased operating costs, lower power consumption, and safer operating conditions. Tests have illustrated the disclosed method produces silicon with a purity that compared favorably (i.e., had similar purity) with commercially available electronic grade silicon. Additionally, repeated experiments indicate that yields decreased when the concentration of sodium was relatively low or if the reaction (i.e., the disclosed process) was allowed to proceed for an extended period of time (compared to the usual process time) the liquid ammonia.

[0044] Prior art processes often employ high heat (i.e., 1100°C in the case of the Siemens reaction) and thus are susceptible to leaving residual impurities in the separated silicon. Further, the reaction is costly, require high power consumption, and can be dangerous due to the necessary equipment to provide such heat and the chemicals involved. By contrast, the disclosed method occurs in the presence of liquid ammonia, which retains the reducing power of the alkali or alkaline earth metal at much lower temperatures (i.e., below the boiling point of the solvent). At normal atmospheric pressure (i.e., 1 atm) ammonia boils at -ATTY DOCKET NO. SAUTER-002AWO33.3C, thus the disclosed method can be run at or above normal atmospheric pressure.

[0045] One notable aspect of the disclosed process is the use of a solvent, specifically one that retains the reducing power of sodium or other alkali metals. Prior processes merely combined sodium and sodium fluosilicate to produce silicon. By contrast, the disclosed process utilizes ammonia or another amine (e.g., trimethylamine with a boiling point of 3.5 °C) as this solvent enabling the reaction to run at a low temperature. Low temperature referring to a temperature at or below the boiling point of the solvent (i.e., for ammonia at normal atmospheric pressure (1 atm), this would be a temperature at or below about - 33.3 ° C (+ / - 1 °C)). Following, the disclosed process can occur at pressures above normal atmospheric pressure (1 atm), indicative of the order of magnitude for the low temperature. Further, the boiling temperature of the solution (i.e., the solvent) will depend on the concentration of the solute, but not significantly, certainly not in orders of magnitude.

[0046] Moreover, the reaction advantageously runs in a solvated state. The solvated state is the process by which solvent molecules surround and form weak bonds with solute ions or molecules. A solvated electron is an uncoupled electron in a solution after a metal donates an electron, and is stabilized temporarily in the solution by nearby solvent molecules. Accordingly, the solvated state stabilizes the solute within the solution. While in a solvated state, sodium notably retains its reducing power in a liquid state. The disclosed silicon purification process occurs in a solvated state and utilizes the strong reducing power of sodium.

[0047] Further, liquid ammonia is notably effective at dissolving metals, resulting in the solvated state. Specifically, liquid ammonia dissolves all of the alkali metals. When a metal (i.e., sodium) dissolves in liquid ammonia it donates electrons to the solvent, resulting in solvated electrons with metallic behavior resulting in a disordered liquid metal. The ammonia molecules are attracted to the negative charge and orient their dipoles forming a type of hole around the electron, stabilizing the electron. This advantageous quality further enables the disclosed process when performed with ammonia to occur in a solvated state.ATTY DOCKET NO. SAUTER-002AWO

[0048] Metal-ammonia solutions, such as those disclosed herein, can be used to intercalate a range of layered materials, which can then be removed in solvents, to produce ionic solutions of two-dimensional materials. The reaction may take place either in a batch or a continuous process. The reaction can occur at a range of different temperatures and pressures (depending on various factors, such as the solvent used). The production of single crystals can occur at a pressure of 100 atm and 115 °C, which could eliminate the step of producing single crystal boules by the Czochralski method and slicing the crystals into wafers for use. Further, the reaction can produce a ‘ribbon’ of silicon, which refers to silicon appropriate for solar cells (often produced by solidifying sheets of silicon). The produced ribbon silicon can have sufficient smoothness for use in photovoltaic cells, and, similar to the benefits described above, can be produced at decreased operating costs, lower power consumption, and safer operating conditions.

[0049] Further, when performed in practice, the process included dissolving sodium in a liquid anhydrous ammonia, resulting in a precipitation with a blue or copper color. Said copper / bronze color is indicative of a higher (> 3 molar) concentration. This coloring indicates a greater reducing activity with greater concentration of sodium in the solution. Following, sodium fluosilicate was included in the disclosed process, to take advantage of the greater reducing activity with the greater concentration of sodium in the solution.

[0050] Various embodiments of the concepts, systems, devices, structures and techniques sought to be protected are described herein with reference to the related drawings. Alternative embodiments can be devised without departing from the scope of the concepts, systems, devices, structures and techniques described herein. It is noted that various connections and positional relationships (e.g., over, below, adjacent, etc.) are set forth between elements in the following description and in the drawings. These connections and / or positional relationships, unless specified otherwise, can be direct or indirect, and the described concepts, systems, devices, structures and techniques are not intended to be limiting in this respect. Accordingly, a coupling of entities can refer to either a direct or an indirectATTY DOCKET NO. SAUTER-002AWO coupling, and a positional relationship between entities can be a direct or indirect positional relationship.

[0051] The following definitions and abbreviations are to be used for the interpretation of the claims and the specification.

[0052] As used herein, the terms "comprises," "comprising,” "includes," "including," "has," "having," "contains" or "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, a mixture, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but can include other elements not expressly listed or inherent to such composition, mixture, process, method, article, or apparatus.

[0053] The terms "one or more" and "at least one " are understood to include any integer number greater than or equal to one, i.e. one, two, three, four, etc.

[0054] References in the specification to "one embodiment,” "an embodiment," "an example embodiment," etc., indicate that the embodiment described can include a particular feature, structure, or characteristic, but every embodiment can include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0055] Use of ordinal terms such as “first,” “second,” “third,” etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.

[0056] The terms “approximately,” “substantially” and “about” may be used to mean within ±20% of a target value in some embodiments, within ±10% of a target value in some embodiments, within ±5% of a target value in some embodiments,ATTY DOCKET NO. SAUTER-002AWO and yet within ±2% of a target value in some embodiments. For example, the terms “substantially equal” or “substantially equal to” may be used to refer to values that are within ±20% of one another in some embodiments, within ±10% of one another in some embodiments, within ±5% of one another in some embodiments, and yet within ±2% of one another in some embodiments. The terms “approximately,” “substantially” and “about” may include the target value.

[0057] It is to be understood that the disclosed subject matter is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The disclosed subject matter is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods, and systems for carrying out the several purposes of the disclosed subject matter. Therefore, the claims should be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the disclosed subject matter.

[0058] Although the disclosed subject matter has been described and illustrated in the foregoing exemplary embodiments, it is understood that the present disclosure has been made only by way of example, and that numerous changes in the details of implementation of the disclosed subject matter may be made without departing from the spirit and scope of the disclosed subject matter.

Claims

ATTY DOCKET NO. SAUTER-002AWOWhat is claimed is:1 . A method of producing purified silicon, comprising: providing an alkali or alkaline earth metal and a metallic or aminated halide salt of silicon; combining the alkali or alkaline earth metal and metallic or aminated halide salt of silicon in a liquid medium to form a precipitate; combining the precipitate with sulfuric acid or another acid to form a byproduct and silicon; and recovering the purified silicon.

2. The method of producing a purified silicon of claim 1 , wherein the liquid medium is an amine or ammonia.

3. The method of producing a purified silicon of claim 2, further comprising combining the alkali or alkaline earth metal and metallic or aminated halide salt of silicon at a low temperature such that the amine or ammonia are in a liquid phase.

4. The method of producing a purified silicon of claim 3, further comprising combining the alkali or alkaline earth metal and metallic or aminated halide salt of silicon at a temperature of about 115°C and a pressure of about 100 atm.

5. The method of producing a purified silicon of claim 1 , wherein the alkali or alkaline earth metal is sodium.

6. The method of producing a purified silicon of claim 1 , wherein the metallic or aminated halide salt of silicon is a alkali metal silicate, an alkaline earth metal silicate, or a transition metal silicate.

7. The method of producing a purified silicon of claim 1 , wherein the metallic or aminated halide salt of silicon is sodium hexafluorosilicate or sodium fluorosilicate.ATTY DOCKET NO. SAUTER-002AWO8. The method of producing a purified silicon of claim 1 , further comprising grinding the alkali or alkaline earth metal and the metallic or aminated halide salt of silicon under nitrogen atmosphere, wherein the liquid medium is anhydrous liquid ammonia or an amine.

9. The method of producing a purified silicon of claim 1 , further comprising dissolving the alkali or alkaline earth metal in anhydrous liquid ammonia to form about a three normal or greater solution then adding the metallic or aminated halide salt of silicon, wherein recovering the purified silicon further comprises washing the silicon with water to remove the byproducts.

10. The method of producing a purified silicon of claim 1 , further comprising providing an alkali or alkaline earth metal dispersion and washing an alkali or alkaline earth metal from the metal dispersion with petroleum ether or a solvent to provide the alkali or alkaline earth metal.1 1. The method of producing a purified silicon of claim 1 , further comprising mixing the alkali or alkaline earth metal, metallic or aminated halide salt of silicon, and liquid medium with a stirring device.

12. A method of producing a purified metal, comprising: providing an alkali or alkaline earth metal and a metallic or aminated halide salt of the purified metal; combining the alkali or alkaline earth metal and the metallic or aminated halide salt of the purified metal in a liquid amine or liquid ammonia to form a precipitate; combining the precipitate with sulfuric acid or another acid to form a byproduct and the purified metal; and recovering the purified metal.ATTY DOCKET NO. SAUTER-002AWO13. The method of producing a purified metal of claim 12, wherein the purified metal is a metal of an element selected from the group of elements from group II,III, IV, V, or VI of the periodic table of the elements.

14. The method of producing a purified metal of claim 13, wherein the purified metal is a metal of an element selected from the group of elements comprising beryllium, boron, scandium, arsenic, yttrium, titanium, zirconium, hafnium, thorium, vanadium, niobium, tantalum, chromium, germanium, molybdenum, gallium, selenium, and tungsten.

15. The method of producing a purified metal of claim 13, wherein the purified metal is a metal of an element selected from group II or group III .

16. The method of producing a purified metal of claim 12, further comprising combining the alkali or alkaline earth metal and the metallic or aminated halide salt of the purified metal at a low temperature such that the amine or ammonia are in a liquid phase.

17. The method of producing a purified metal of claim 16, further comprising combining the alkali or alkaline earth metal and metallic or aminated halide salt of the purified metal at a temperature of about 115°C and a pressure of about 100 atm.

18. The method of producing a purified metal of claim 12, further comprising grinding the alkali or alkaline earth metal and metallic or aminated halide salt of the purified metal under nitrogen atmosphere, wherein the liquid amine or liquid ammonia is anhydrous liquid ammonia.

19. The method of producing a purified metal of claim 12, further comprising dissolving the alkali or alkaline earth metal in anhydrous liquid ammonia to form about a three normal or greater solution then adding the metallic or aminated halideATTY DOCKET NO. SAUTER-002AWO salt of the purified metal, wherein recovering the purified metal further comprises washing the purified metal with water to remove the byproducts.

20. The method of producing a purified metal of claim 12, further comprises mixing the alkali or alkaline earth metal, metallic or aminated halide salt of the purified metal, and liquid amine or liquid ammonia with a stirring device.

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