Silicon Reduction of Iron Oxide

Abstract

Systems and methods for producing iron from iron oxide using silicon are disclosed. Slag is mixed with a first ore. The slag includes metallic silicon. The first ore includes iron oxide. The mixture is heated sufficient to initiate reduction of the iron oxide by the metallic silicon, producing metallic iron and silicon oxides.

Claims

1. A method for producing metallic iron, comprising: mixing a slag, the slag comprising metallic silicon, with a first ore, the first ore comprising iron oxide, to produce a first mixture; and reducing the iron oxide by oxidation of the metallic silicon, producing metallic iron and silicon oxides.

2. The method of claim 1, further comprising deoxygenating a second ore to produce the metallic silicon and an oxygen gas stream.

3. The method of claim 2, wherein a source of the first ore is the source of the second ore.

4. The method of claim 1, further comprising separating the metallic iron from the silicon oxides.

5. The method of claim 4, wherein separating the metallic iron from the silicon oxides comprises a process selected from the group consisting of magnetic separation, electrostatic separation, physical separation based on differences in particle size, physical separation based on differences in shape, physical separation based on differences in density, and vacuum vaporization of silicon monoxide out of the metallic iron.

6. The method of claim 1, further comprising producing heat by reducing the iron oxide by oxidation of the metallic silicon.

7. The method of claim 6, further comprising transferring the heat to Lunar habitats, transferring the heat to Lunar unit operations, converting the heat to electricity, or combinations thereof.

8. The method of claim 6, further comprising transferring the heat for use during the Lunar night.

9. The method of claim 6, further comprising separating silicon monoxide from the metallic iron by vacuum vaporization of the silicon monoxide, and wherein the silicon monoxide is refined to a silicon product, a silicon dioxide product, or both.

10. The method of claim 1, further comprising heating the slag and the first ore to initiate reduction of the iron oxide.

11. The method of claim 10, wherein heating the slag and the first ore comprises beneficiating the slag and the first ore until frictional heat initiates reduction.

12. A system for producing metallic iron, comprising: a crucible to mix a slag and a first ore to form a first mixture, the slag comprising metallic silicon and the first ore comprising iron oxide; and either: a heater to heat the crucible to a temperature to initiate the iron oxide reduction by the metallic silicon, producing metallic iron and silicon oxides; or a heater to heat the slag to a molten temperature such that mixing the slag and the first ore initiates iron oxide reduction by the metallic silicon, producing metallic iron and silicon oxides.

13. The system of claim 12, further comprising a separator to pretreat the slag by removing non-metals from the slag.

14. The system of claim 12, further comprising operating the crucible in vacuum on the Lunar surface and wherein off-gases from the first mixture leave the first mixture into the vacuum.

15. The system of claim 14, further comprising a condenser to recover the off-gases, wherein the off-gases are selected from the group consisting of water, phosphorus, phosphorus-containing compounds, sulfur, sulfur-containing compounds, metals, metal oxides, silicon monoxide, mercury, and mercury containing compounds.

16. The system of claim 12, wherein the heater is disengaged after the reduction initiates as the reduction produces excess heat.

17. The system of claim 12, further comprising a reduction unit to deoxygenate a second ore to produce the slag and an oxygen gas stream.

18. The system of claim 12, wherein a pre-heater moltens the silicon metal, moltens the first ore, or moltens both before mixing the silicon metal with the first ore.

19. The system of claim 18, further comprising a vent to Lunar vacuum to provide vacuum to separate silicon monoxide from the metallic iron by vacuum vaporization of the silicon monoxide, and further comprising a refining unit to refine the silicon monoxide to a silicon product, a silicon dioxide product, or both.

20. A system for producing metallic iron, comprising: a separator to separate a slag into an oxide residue and a metal product; a crucible to mix the metal product and a first ore, the metal product comprising metallic silicon and the first ore comprising iron oxide; and either: a heater to heat the crucible to a temperature to initiate the iron oxide reduction by the metallic silicon, producing metallic iron and silicon oxides; or a heater to molten the metal product, the first ore, or both before mixing, whereby mixing the slag and the first ore initiates iron oxide reduction by the metallic silicon, producing metallic iron and silicon oxides.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0011] The following drawings are provided to illustrate certain examples described herein. The drawings are merely illustrative and are not intended to limit the scope of the present disclosure or the present claims, and are not intended to show every potential feature or embodiment of the present disclosure or the present claims. The drawings are not necessarily drawn to scale; in some instances, certain elements of the drawing may be enlarged with respect to other elements of the drawing for purposes of illustration.

[0012] FIG. 1 is a block flow diagram showing an example system for producing iron.

[0013] FIG. 2 is a block diagram showing an example method for producing iron.

[0014] FIG. 3 is a block diagram showing an example method for producing iron.

[0015] FIG. 4 is a process flow diagram showing unit operation 104 from FIG. 1.

[0016] FIG. 5 is a process flow diagram showing unit operation 106 from FIG. 1.

[0017] FIG. 6 is a process flow diagram showing unit operation 108 from FIG. 1 and slag handling.

DETAILED DESCRIPTION

[0018] The following description recites various example systems and methods disclosed herein. No particular example is intended to define the scope of the present systems and methods. Rather, the examples provide non-limiting examples of various systems, and methods, that are included within the scope of the present disclosure and the present claims. The description is to be read from the perspective of one of ordinary skill in the art. Therefore, information that is well known to the ordinarily skilled artisan is not necessarily included.

[0019] The following terms and phrases have the meanings indicated below, unless otherwise provided herein. This disclosure may employ other terms and phrases not expressly defined herein. Such other terms and phrases shall have the meanings that they would possess within the context of this disclosure to those of ordinary skill in the art. In some instances, a term or phrase may be defined in the singular or plural. In such instances, it is understood that any term in the singular may include its plural counterpart and vice versa, unless expressly indicated to the contrary.

[0020] As used herein, the singular forms a, an, and the include plural referents unless the context clearly dictates otherwise. For example, reference to a substituent encompasses a single substituent as well as two or more substituents, and the like.

[0021] As used herein, for example, for instance, such as, illustratively, or including are meant to introduce examples that further clarify more general subject matter. Unless otherwise expressly indicated, such examples are provided only as an aid for understanding embodiments illustrated in the present disclosure and are not meant to be limiting in any fashion. Nor do these phrases indicate any kind of preference for the disclosed example.

[0022] As used herein, oxides are oxide containing chemicals that may occur in the form of multi-element oxides, silicates, and aluminates, and often as distinct mineral types. All oxides, silicates, and aluminates are referred to as oxides herein.

[0023] As used herein, slag refers to any of the following terms. Slag, dross, waste ore, mineral processing byproducts, or any mix of the results of oxides and metals from a molten unit operation.

[0024] In some examples, the metallic silicon can be sourced from scrap man-made resources such as solar panels, computer chips, and similar silicon containing materials. In some examples, slag and man-made silicon sources are blended.

[0025] The examples, drawings, and descriptions herein disclose utilization systems and methods for carbothermal reduction residue (or any other silicon-metal containing material) to produce metallic iron from relatively low-grade iron oxide feeds.

[0026] A carbothermal reduction module carries out carbothermal reduction. Much of the description herein is directed towards a Lunar application, but the disclosure should not be construed to be limited to Lunar applications. The disclosure can be utilized terrestrially, on Mars, asteroids, comets, or any rocky body, as well as in orbit. The most immediate applications are envisioned on the Moon as a high-yielding oxygen production process. The process generates a deoxygenated residue (DOR) that consists of a metallic phase (mostly silicon containing iron and manganese) and an oxide phase containing oxides of silicon, aluminum, and calcium along with smaller amounts of other oxides present in lunar regolith. The oxide phase of the residue has some potential use as feed to more-advanced oxygen and metal generation processes (such as Molten Regolith Electrolysis). The metallic phase of the DOR has been identified as a potential feed for refinement to produce silicon metal for various applications following significant refining to achieve purities required for solar or electronic applications.

[0027] Given the relatively low demand for silicon metal on the Moon (at least during early phases of exploration and settlement), alternative uses of the metallic phase have been identified that provide a valuable near-term benefit to the lunar economy and infrastructure. This involves the use of the metallic silicon-containing residue as a reducing agent to produce metallic iron from relatively low-grade feeds such as lunar regolith.

[0028] Carbothermal reduction is expected to be carried out by organizations that have tailored the process to the lunar application. In initial implementation, the combined metallic and oxide portions of DOR are expected to be discharged from the reactor system for disposal or potential additional use.

Carbothermal Reduction Residue Separation

[0029] The silicothermic reduction process recovers the metallic fraction of DOR for use as a silicothermic reducing agent for production of metallic iron. Because carbothermal reduction is carried out at high temperature (in excess of 1600 C), the metallic and oxide components are entirely molten. The metallic phase coalesces and separates from the oxide phase due to differences in surface tension. Upon discharge from the reactor, and as the residue cools and solidifies, coalesced metal and oxides exist as separate phases. Recovery of the cooled DOR (from a lunar-derived ceramic pad, for example) with application of soft crushing can then release the brittle, glassy, oxide phase from the metal phase. This crushing action to break the oxide component from the metal phase can be conducted by various means as follows.

[0030] Tumbling in a rotary drum with baffles to break the oxides from the metal phase followed by discharge and feed to physical separation based on differences in particle size, shape, or density. Magnetic separation of the metal phase when the iron concentration is high enough, and if the ferrosilicon structure is correct. Each of these steps can be conducted in the low-pressure lunar environment in hardware delivered from Earth or produced via in-situ resources (such as iron/steel) produced from the proposed methods and system.

[0031] After recovery of the metal phase from the DOR, some additional crushing may be required to achieve a particle size distribution (likely less than about 1 mm) that has sufficient surface area to provide interparticle contact with fresh ore or regolith as described later. If additional crushing of the metallic phase is required, this might be achieved after allowing the metal to be cooled to lunar night time temperatures to boost the brittleness. Under this environment, additional tumbling with hard grinding media or potentially autogenously with coarser silicon metal containing feed could produce the desired size reduction.

[0032] Alternatively, the metallic fraction could be heated, melted, and sprayed to create particles of controlled size as feed to the silicothermic reduction step.

[0033] In one example, separation has no integration with carbothermal reduction. In other examples, integration with carbothermal reduction allows for recovery of the silicon containing metal in a molten state separately from the oxides in DOR. This allows a tailoring of the particle size of the metallic fraction to minimize physical processing needs.

[0034] The oxide portion of DOR is stored for other processing while the metallic portion is advanced to the iron oxide reduction module or maintained in inventory until use.

[0035] In this example, the iron oxide reduction module utilizes a crucible for the molten temperatures and corrosion characteristics of the silicon-containing metal and fresh ore or regolith. In this example, this step is conducted in the low-pressure lunar environment. Because no significant emissions are produced due to the transfer of oxygen from the ore or regolith constituents to the silicon metal, gas handling hardware is not required. However, with appropriate selection of temperatures for the process, some vaporization of contaminants or metals or silicon monoxide will occur. In some examples, condensers will be installed to selectively recover these fumes based on their condensation temperatures.

[0036] The silicothermic reduction process can be initiated in several ways. In one example, the mixture of the silicon metal phase plus fresh ore or regolith is heated (via induction or resistive heating, for example) until the exothermic reaction begins (likely below the melting temperature). In this case, the reaction would generate more heat that would melt the entire contents with no further heat input. As an alternative example, a small localized flow of hot oxygen is provided in proximity to the metallic silicon to generate enough heat initiate a metallothermic reduction reaction that spreads through the entire reaction crucible. In other examples, igniters or small pyrotechnic devices are used to initiate the reaction.

[0037] Because the silicothermic reduction reaction can generate significant excess energy, provisions to recover heat from the reaction system may be installed. In some examples, the heat is removed from the reactor and recovered for heat exchange via a variety of gas- or liquid-based systems for use in preheating additional feed, providing lunar night-survival heat for other hardware and systems, and generating electricity via thermoelectric devices.

[0038] Although many metallothermic reduction systems are operated in batch mode, options to operate in a semi-continuous manner are provided herein to significantly boost the efficiency of heat recovery methods described above. In one example, the metallic and/or regolith constituents can be added incrementally to spread the rate of heat release during reaction. This provides a more-steady heat flow to facilitate heat recovery and transfer. The metallic iron and oxide phases are tapped periodically in a manner similar to that employed in blast furnaces to provide sufficient reaction time while controlling the inventory in the reactor.

[0039] In one example, upon completion of the silicothermic reduction reaction, the molten iron product is tapped separately from the oxide phase as part of metal-oxide slag separation. In one example, the oxide phase is cooled and stored for potential future recycle to carbothermal reduction or for other purposes. In other examples, the metal phase is maintained in the molten phase while transferring to the next step, as in the transfer of iron from blast furnaces to nearby steelmaking facilities. At this point in the example, the metal phase will consist of iron along with manganese, chromium, and small amounts of nickel, depending on the compositions of the feeds to carbothermal reduction and silicothermic reduction.

[0040] In this example, further impurity removal, alloying, and manufacturing are conducted. In this Lunar example, operations occur in a low-pressure lunar environment. Some purification will be achieved in a manner analogous to terrestrial vacuum metallurgy. In one example, the low-pressure environment facilitates the release of dissolved gases (such as oxygen) and more-volatile impurities that can affect steel properties. This reduces the requirements for steel making additives that would otherwise be added to move these constituents to a slag phase. In some examples, additional impurity removal is provided. Contaminants for possible removal include sulfur and phosphorus. Conventional steelmaking methods may be adapted to remove these and other contaminants to the desired levels in a Lunar environment. In one example, the hardening effect of phosphorus is exploited to the benefit of the final steel product by keeping concentrations below required levels. In some examples, the calcium-oxide rich slag components that aid impurity removal are derived from Lunar regolith, or in particular from slags that have elevated concentration of calcium oxide after carbothermal reduction and/or molten regolith electrolysis.

[0041] These examples provide significant flexibility for control of the amount of residual silicon metal in the alloy.

[0042] For lunar applications requiring service temperatures far lower than those designed for on Earth, additional alloying may be required. For example, increasing nickel additions (up to about 10 percent) can increase steel microstructure stability at increasingly lower temperatures. Several other alloying options applied for cryogenic application on Earth are well known. These can be adapted for lunar use under reduced gravity and lack of atmospheric corrosion agents.

[0043] Many lunar regolith compositions contain manganese in concentrations relative to iron that constitute favorable alloying compositions. Therefore, the proposed system and methods carry a built-in advantage for manufacture of low-alloy steel.

[0044] After tapping the molten steel from the refining vessel, the steel can be handled in a manner similar to terrestrial use for the fabrication of components via casting or extrusion. In a lunar application, the recovery of heat as material solidifies and cools is a valuable additional step. A continuous or semi-continuous approach aids the efficiency of heat recovery and exchange.

[0045] An additional benefit of the proposed approach is that a silicothermic reduction based welding approach is provided. This is applied in a manner analogous to terrestrial thermite rail welding, which uses an aluminum metal/iron oxide mix. With appropriate molds and ignition, the thermite reaction creates sufficient heat to reduce the iron oxide to metal, which sinks below the oxides and pours into the weld area. A silicon metal-iron oxide mix thermite mix can be tailored to achieve similar results for field fabrication on the Moon.

[0046] The Lunar ore, provided both in the initial carbothermal reaction or in the metallothermic reaction, may be used as-is or after beneficiation. Beneficiation can include particle size adjustment and separations to alter the concentrations of iron oxide. On the moon, the two ores can be the same or different. They can be of a highlands-type composition (with a relatively high calcium-aluminum-silicate composition and relatively low iron oxide concentration that is more typical near the south pole and over wide regions at lower latitudes) or of a mare-type composition (with a relatively higher iron oxide concentration in basalt and with iron oxide also existing as ilmenite, iron titanate, typically in lower latitude and equatorial regions). In some regions, mare and highlands soils may exist in relatively close proximity, allowing for their separate selection as the carbothermal or metallothermic feed ores. This flexibility allows for the silicon-producing process to create a higher-purity silicon metal product while the iron oxide producing process creates a higher-purity iron oxide feed that can reduce the total mass subjected to silicothermic reduction. With consideration of the presences of the more minor elements (including manganese, an important alloying agent) the final iron metal product composition can be controlled.

[0047] Silicon metal in small amounts can be considered to be a beneficial alloying agent in steel. By reducing the ratio of silicon metal to feed ore to a sub-stoichiometric ratio, the residual silicon concentration in the metal can be controlled to near zero. Conversely, a higher silicon-metal-containing iron product can be obtained by using a slight excess of silicon metal to feed ore ratio. A thermodynamic equilibrium evaluation shows that near complete reaction between iron oxide, manganese oxide, and silicon metal takes place up to at least 1600 C. Above 1600 C, the extent of reduction of FeO to Fe gradually drops. In vacuum conditions, iron metal, manganese metal, and silicon monoxide (SiO) would be partially vaporized above about 1600 C. This may be leveraged to perform at least some product refinement, or allow for recovery of a relatively pure SiO product that is reoxidized to SiO2 as a glass component or further reduced as a first step in manufacture of solar or electronic grade silicon.

[0048] In some examples, as an initial step toward the silicothermic reduction of metal oxides contained in fresh regolith, the metallic constituent of the carbothermal reduction residue is separated from the remaining oxidized portion of the residue. The carbothermal reduction residue containing both the metallic and oxide fractions may be used for silicothermic reduction of oxides in fresh regolith without separation but with reduced thermal efficiency. The metallic phase of the carbothermal reduction residue may be separated from the oxide phase while molten. The metallic fraction of the carbothermal reduction residue may be separated from solidified residue by crushing to release coalesced metal from the oxide phase followed by physical separation.

[0049] The reaction of metallic silicon with Lunar ore may be carried out by mixing the components. The reaction may be initiated as a solid-solid reaction when sufficient interparticle contact is present between the metal and oxide phases. Beneficiation to optimize particle packing and/or physical compression may be used to boost interparticle contact. The reaction may be initiated by gradually heating until the exothermic silicothermic reaction starts, at which time it will self sustain. The reaction may be initiated at relatively low temperature by a small, concentrated heat source, like a pyrotechnic discharge or localized oxidation of an initiating agent such as the already-present silicon metal or a small addition of a reactive metal such as magnesium. The reactants may be charged with the full target mass of each constituent prior to initiating reaction. Alternatively, one reactant may be metered into the other reactant to control temperature and rate of reaction. Heat removal may be utilized to control temperature while providing a high-quality (high-temperature) heat source. The process may be conducted as a typical batch thermite reaction. Alternatively, the reactants may be introduced in a semi-continuous fashion while periodically removing the resulting metal and slag constituents.

[0050] The reaction of silicon metal with Lunar ore may be used as a welding method (similar to the aluminothermic reduction of iron oxide for terrestrial rail welding) as part of a manufacturing process (and for remote/field fabrication).

[0051] Lunar iron oxides are generally less oxidized that those on earth. Most iron on the moon exists as ferrous iron (+2) with small amounts of metallic iron (from micrometeorites or from reduction of iron oxide upon high-temperature impact of micrometeorites). Iron on Earth is more typically in the form of ferrous or ferric (+3). The effect of this is that less silicon metal is required on the moon than on earth to produce metallic iron.

[0052] Now referring to FIG. 1, FIG. 1 is a block flow diagram showing an example system 100 for producing iron that may be used in some examples provided herein. This example is purely illustrative, and multiple other examples are envisioned or may be readily envisioned without undue experimentation.

[0053] The example in FIG. 1 is based on Lunar mining, but terrestrial, Martian, asteroid, comet, or other planetary body ores could be used. In examples where the mining occurs on a planetary body with an atmosphere, any steps involving vacuum would require the appropriate equipment to produce vacuum, whereas vacuum is made on the moon and other no-atmosphere planetary bodies by simply opening a valve or similar to the vacuum of space. Examples on any planetary body are readily understood using the examples herein.

[0054] Lunar regolith is as complex an ore body as any Earth ore. There are metal oxides, metal sulfides, and in some locations, volatiles and other contaminants. For this example, iron oxide is the primary ore of interest, while other ores, listed elsewhere, are of secondary concern.

[0055] At 100, raw Lunar regolith stream 101, containing iron oxide, is passed into a carbothermal reduction module 102 where heat is used to melt stream 101 and evolve an oxygen product stream 103 and produce a carbothermal reduction residue stream 105. Stream 105 contains reduced iron, also referred to as metallic iron or iron metal, reduced silicon, also referred to as metallic silicon or silicon metal, other reduced metals, as well as any remaining oxides, sulfides, and contaminants as slag. The molten stream 105 is passed into a carbothermal reduction residue separation unit 104. Stream 105 is cooled below molten temperatures and the slag and metals separated in unit 104 into carbothermal reduction residue oxide byproduct stream 109 and carbothermal reduction residue metal product 107. In this example, the metal product 107 still contains a small amount of slag. As is known in mineral processing, complete separation can be accomplished by increasingly complex unit operations. Therefore, the metal product stream 107 contains as much slag as the process design allows for. Stream 107 is combined with more raw Lunar regolith stream 111 in iron oxide reduction module 106. Stream 111 can be from the same source as stream 101, or can be from a different Lunar regolith source. The goal of reduction module 106 is to reduce iron oxide with silicon metal. The reduction module 106 of this example can include multiple sub-unit operations. In this example, a beneficiation unit, such as a grinder, reduces particle size of the metal product stream 107 and the ore stream 111 to reduce the heat requirement for initiation of the reduction reaction. The grinder may even produce enough heat to initiate the reaction, at which point the mixture is moved into a crucible for the reduction reaction. The beneficiation of this example brings the mixture near the temperature to initiate reaction, but the final heat is provided by inductive heating in the crucible. The metallic silicon in the mixture reduces the iron oxide in the mixture, and the heat of reaction causes the mixture to molten and self-propagate. In some examples, the heat from this reaction is sufficient that removal of the heat is required, and can even be beneficial. These examples will be shown in greater detail in FIGS. 4 through 6.

[0056] The molten slag 113 produced by the reaction, which includes metallic iron and silicon oxides, is passed to a metal-oxide slag separation unit 108. The silicon oxides include both silicon dioxide and silicon monoxide. The separation unit 108 of this example includes multiple sub-unit operations. First, vacuum, which is free and omnipresent on the Lunar surface, can be utilized to boil off silicon monoxide and any other volatile contaminants. The list of potential contaminants is the list of naturally-occurring elements on the periodic table, minus iron, as Lunar ore is just as complex as terrestrial ore. These are discussed in greater detail herein. Unit 108 would further include units to cool and physically separate the slag from the metal product. The reduction oxide byproduct stream 117 (slag) is removed while the metallic iron product stream 115 is passed on to impurity removal, alloying, and manufacturing units 110.

[0057] Unit 110 is actually several unit operations. Impurity removal agents 123 are made available to the system and impurities such as sulfur, phosphorus, and other contaminants that made it through to this stage are removed as impurities stream 121. Alloying agents 125 are added to the purified metal and the steel product 119 is either shipped as a raw material or manufacturing is completed in unit 110 before the steel product 119 is shipped.

[0058] The examples in FIG. 1 have greater detail and context provided below and are to be understood in the context provided throughout.

[0059] In the example of FIG. 1, stream 105 is cooled below molten temperatures for separation, but in another example, separation unit 104 separates the metal product 107 from the slag 109 while still molten, thereby passing stream 107 into the reduction module at molten temperatures, allowing the reduction of ore by the silicon metal to occur without a heater in the reduction module 106.

[0060] Illustratively, FIG. 2 is a block diagram showing an example method 2000 for producing iron that may be used in some of the examples provided herein. Method 2000 may include mixing a slag, the slag including metallic silicon, with a first ore, the first ore including iron oxide, to produce a first mixture (operation 2001). Method 2000 may include reducing the iron oxide by oxidation of the metallic silicon, producing metallic iron and silicon oxides (operation 2002).

[0061] Illustratively, FIG. 3 is a block diagram showing an example method 3000 for producing iron that may be used in some of the examples provided herein. Method 3000 may include mixing a slag, the slag including metallic silicon, with a first ore, the first ore including iron oxide, to produce a first mixture (operation 3001). Method 3000 may include heating the first mixture (operation 3002). Method 3000 may include reducing the iron oxide by oxidation of the metallic silicon, producing metallic iron and silicon oxides (operation 3003). Method 3000 may include producing heat and transferring the heat to Lunar habitats or Lunar unit operations, or converting the heat to electricity (operation 3004).

[0062] Illustratively, FIG. 4 is a process flow diagram showing an example of unit operation 104 from FIG. 1 at 400. FIG. 5 is a process flow diagram showing an example of unit operation 106 from FIG. 1 at 500. FIG. 6 is a process flow diagram showing an example of unit operation 108 from FIG. 1 and slag handling at 600. Molten carbothermal reduction residue stream 105 passes into carbothermal residue separation unit 104, which consists of slag cooling and solidification 402, crusher 404, separator 406, metal product auger 408, oxide auger 410, and storage bin 412. Stream 105 is cooling and solidified in unit operation 402. Heat stream 409 is removed. This is especially important in Lunar environments, where heat dissipation is by conduction or radiation, as atmospheric convection is not available. Solid slag 401 is passed through a crusher 404 to size the slag and metal sufficiently small for proper separation. Separator 406 separates the oxides 109 from the metal product 107. These are conveyed through augers 410 and 408, respectively. The oxides 109 are stored in a storage bin 412 while the metal product 107 is passed on to unit operation 106, in FIG. 5.

[0063] At 500, Unit operation 106 from FIG. 1 consists of a crucible 506 with heater 508, an auger 502, and a condenser 504. Metal product 107 is dropped into crucible 506 along with new ore 111, conveyed to the crucible 506 via an auger 502. The crucible 506 is heated by a heater 508, which can be inductive, resistive, or other appropriate heating devices. Heating the crucible 506 moltens the mixture, initiating the reduction of iron oxide by silicon metal. The resultant reaction produces molten slag 113 which passes on to unit operation 108, in FIG. 6. Contaminants and other volatiles can offgas as stream 503 and be sent to condenser 504. Condensed products 505 can result. The contaminants are listed throughout this disclosure, but of note for this example is silicon monoxide, which offgases readily in the vacuum of the Lunar environment and can be condensed and collected as another product.

[0064] At 600, unit operation 108 is shown for separating molten slag 113 into molten metal 115 and molten slag 117, as in FIG. 1. Added to this example is the slag cooling and solidification unit 602. Heat is removed from this unit as stream 603, while solid slag 601 is augered via auger 604 to a hopper 606 as solid slag byproduct 605.

[0065] In some examples, the slag further includes metals selected from the group consisting of iron, manganese, copper, cobalt, nickel, and chromium.

[0066] In some examples, the method includes deoxygenating a second ore to produce the metallic silicon and an oxygen gas stream.

[0067] In some examples, a source of the first ore is the source of the second ore.

[0068] In some examples, the method includes separating the metallic iron from the silicon oxides.

[0069] In some examples, separating the metallic iron from the silicon oxides includes a process selected from the group consisting of magnetic separation, electrostatic separation, physical separation based on differences in particle size, physical separation based on differences in shape, physical separation based on differences in density, and vacuum vaporization of silicon monoxide out of the metallic iron.

[0070] In some examples, the first ore is selected from the group consisting of Lunar ore, Martian ore, asteroid ore, comet ore, and terrestrial ore, and the second ore is selected from the group consisting of Lunar ore, Martian ore, asteroid ore, comet ore, and terrestrial ore.

[0071] In some examples, the first ore further includes an oxide ore selected from the group consisting of magnesium oxide, manganese oxide, silver oxide, cadmium oxide, lead oxide, copper oxide, nickel oxide, cobalt oxide, tin oxide, zinc oxide, chromium oxide, niobium oxide, vanadium oxide, sodium oxide, and potassium oxide. The method further includes reducing the oxide ore by oxidation of the silicon metal, producing a metal selected from the group consisting of magnesium, manganese, silver, cadmium, lead, copper, nickel, cobalt, tin, zinc, chromium, niobium, vanadium, sodium, and potassium, respectively.

[0072] In some examples, the slag is produced using energy produced during a Lunar day by a process selected from the group consisting of nuclear fission, nuclear fusion, and radioisotope thermoelectric.

[0073] In some examples, the slag is produced using energy produced during a Lunar day by a process selected from the group consisting of solar electric, direct solar thermal, and indirect solar thermal. The iron oxide reduced by oxidation of the metallic silicon further produces heat. The method includes transferring the heat to Lunar habitats, transferring the heat to Lunar unit operations, converting the heat to electricity, or combinations thereof. The method includes transferring the heat for use during the Lunar night.

[0074] In some examples, the silicon metal is molten, the first ore is molten, or both are molten while mixing the silicon metal with the first ore.

[0075] In some examples, silicon monoxide is separated from the metallic iron by vacuum vaporization of the silicon monoxide, and the silicon monoxide is refined to a silicon product, a silicon dioxide product, or both.

[0076] In some examples, heating the slag and the first ore initiates reduction of the iron oxide.

[0077] In some examples, heating the slag and the first ore involves beneficiating the slag and the first ore until frictional heat initiates reduction.

[0078] In some examples, an additional dose of the first ore is added to the first mixture while the first mixture is reducing, the additional dose of the first ore modifying a temperature of the first mixture.

[0079] In some examples, a separator pretreats the slag by removing non-metals from the slag. The crucible is operated in vacuum on the Lunar surface and off-gases from the first mixture leave the first mixture into the vacuum. A condenser recovers at least a portion of the off-gases. The off-gases are selected from the group consisting of water, phosphorus, phosphorus-containing compounds, sulfur, sulfur-containing compounds, metals, metal oxides, silicon monoxide, mercury, and mercury containing compounds.

[0080] The crucible is made of a refractory material selected from the group consisting of graphite, carbides, ceramic oxides, and refractory metals.

[0081] In some examples, the heater is selected from the group consisting of an inductive heater, a resistive heater, an injector to send a bolus of oxygen into the metallic silicon, an igniter, and a pyrotechnic device.

[0082] In some examples, the heater is disengaged after the reduction initiates as the reduction produces excess heat.

[0083] In some examples, heat exchangers are configured to transfer the excess heat from the crucible to heat sinks.

[0084] In some examples, the heat sinks are chosen from a list including a Lunar habitat, Lunar unit operations, and a thermoelectric device.

[0085] In some examples, the slag further includes metals selected from the group consisting of iron, manganese, copper, cobalt, nickel, and chromium.

[0086] In some examples, a reduction unit deoxygenates a second ore to produce the slag and an oxygen gas stream.

[0087] In some examples, a source of the first ore is the source of the second ore.

[0088] In some examples, a separator separate the metallic iron from the silicon oxides.

[0089] In some examples, the separator is selected from a group consisting of magnetic separators, electrostatic separators, physical separators based on differences in particle size, physical separators based on differences in shape, physical separators based on differences in density, and a vent to vacuum for vaporization of silicon monoxide out of the metallic iron.

[0090] In some examples, the first ore is selected from the group consisting of Lunar ore, Martian ore, asteroid ore, comet ore, and terrestrial ore, and the second ore is selected from the group consisting of Lunar ore, Martian ore, asteroid ore, comet ore, and terrestrial ore.

[0091] In some examples, the first ore further includes an oxide ore selected from the group consisting of magnesium oxide, manganese oxide, silver oxide, cadmium oxide, lead oxide, copper oxide, nickel oxide, cobalt oxide, tin oxide, zinc oxide, chromium oxide, niobium oxide, vanadium oxide, sodium oxide, and potassium oxide, and the crucible is further configured to reduce the oxide ore by oxidation of the silicon metal and produce a metal selected from the group consisting of magnesium, manganese, silver, cadmium, lead, copper, nickel, cobalt, tin, zinc, chromium, niobium, vanadium, sodium, and potassium, respectively.

[0092] In some examples, an energy producing device provides energy to produce the slag during a Lunar day from the group consisting of nuclear fission, nuclear fusion, and radioisotope thermoelectric.

[0093] In some examples, an energy producing device provides energy to produce the slag during a Lunar day from the group consisting of solar electric, direct solar thermal, and indirect solar thermal.

[0094] In some examples, the crucible further produces heat by reducing the iron oxide by oxidation of the metallic silicon.

[0095] In some examples, heat exchangers transfers the heat to Lunar habitats, transfer the heat to Lunar unit operations, convert the heat to electricity, or combinations thereof.

[0096] In some examples, the heat is transferred for use during the Lunar night.

[0097] In some examples, a pre-heater moltens the silicon metal, moltens the first ore, or moltens both before mixing the silicon metal with the first ore.

[0098] In some examples, a vent to Lunar vacuum provides vacuum to separate silicon monoxide from the metallic iron by vacuum vaporization of the silicon monoxide. A refining unit refines the silicon monoxide to a silicon product, a silicon dioxide product, or both.

[0099] In some examples, a heater heats the slag and the first ore to initiate reduction of the iron oxide.

[0100] In some examples, the heater is a beneficiation unit to provide frictional heat until the frictional heat initiates reduction.

[0101] In some examples, a dosing unit adds an additional dose of the first ore to the first mixture while the first mixture is reducing, the additional dose of the first ore modifying a temperature of the first mixture.

[0102] In some examples, the silicon metal is provided from local sources, local being sourced from non-terrestrial sources.

[0103] The invention has been described with reference to various examples. Nevertheless, it is understood that many variations and modifications may be made while remaining within the spirit and scope of the invention.