Ore Processing Method

Abstract

The present invention relates to a method for providing an ore concentrate solution suitable for mineral processing, the method comprising contacting an ore with one or more metal bases at a high temperature. The one or more metal bases at a high temperature may constitute a super-alkaline medium that partially or completely dissolves the ore. Typically, the one or more metal bases are alkali metal bases, preferably selected from lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, or cesium hydroxide, or alkaline earth bases, preferably selected from calcium hydroxide, barium hydroxide, or strontium hydroxide. The one or more metal bases at a high temperature may constitute a super-alkaline medium that partially or completely dissolves the ore.

Description

Detailed Description of the Invention

[0001] [Technical field] The present invention relates to the field of ore processing.

[0002] In one aspect, the invention relates to the processing of ores to provide valuable products, such as metals, metal compounds, metalloids, or intermediate compounds, suitable for further downstream processing.

[0003] In another aspect, the present invention is suitable for providing the treated ore to downstream mineral processing steps.

[0004] In one particular embodiment, the present invention is suitable for providing the treated ore to downstream electrometallurgical processes such as electrodeposition and electrowinning.

[0005] While it will be convenient to describe the invention below in terms of iron ore, it will be understood that the invention is not so limited and extends to a variety of ores and a variety of value products, including metal and metalloid based products. Furthermore, it will also be convenient to describe the invention in terms of providing processed material for electrometallurgy, but it can be extended to other forms of extractive metallurgy and ore beneficiation processes.

[0006] [Background technology] It will be understood that any discussion of a document, device, act, or finding within this specification is included to explain the context of the invention. Moreover, the discussion throughout this specification arises out of the inventor's knowledge and / or identification by the inventor of problems in the related art. Moreover, any discussion of material such as a document, device, act, or finding within this specification is included to explain the context of the invention in terms of the inventor's knowledge and experience, and therefore, no such discussion should be taken as an admission that any of the material formed part of the prior art base or common general knowledge in the relevant art in Australia or elsewhere at or before the priority date of the disclosure and claims herein.

[0007] The term "crude ore" refers to ores, metals, metalloids, minerals, and other products containing mineral matter that have been mined or removed from the natural environment and may have been classified or crushed. The crude ore may be further processed or beneficiated as an industrial process to separate the valuable minerals from the waste or gangue. "Beneficiation" is a term used to refer to any process that improves or contributes to the economic value of the ore, thereby providing a higher-grade product (called "ore concentrate") and a waste stream.

[0008] Further processing generally involves extractive metallurgy to remove metals from natural deposits. Extractive metallurgy techniques are typically divided into four types: hydrometallurgy, pyrometallurgy, ionometallurgy, and electrometallurgy.

[0009] Electrometallurgy involves metallurgical processing carried out in some type of electrolytic cell. The most common electrometallurgical processes are electrorefining and electrowinning.

[0010] Electrowinning is an electrolytic process used to recover metals from aqueous solutions, usually after the ore has undergone one or more hydrometallurgical processes. Metals are recovered by depositing them on the cathode by passing an electric current from an inert anode into a leach solution containing dissolved metal ions.

[0011] Electrorefining uses a similar process to remove impurities from metals. In electrorefining, the anode consists of the impure metal to be refined. The impure metal anode is oxidized, dissolving the metal into solution. The metal ions flow through an acidic electrolyte toward the cathode, where the pure metal is deposited.

[0012] Ionometallurgy uses ionic liquids or eutectic melts to extract and / or convert metals and minerals.

[0013] In addition to metals, many commercially valuable products can be obtained from ores. For example, silica is an abundant and chemically complex substance obtained from several minerals, particularly quartz. Silica is extremely valuable to the microelectronics, food, and pharmaceutical industries.

[0014] The mining industry is constantly seeking "green" ore processing techniques to reduce emissions and waste.

[0015] For example, the steel industry accounts for approximately 7% of global carbon dioxide emissions, making reducing carbon pollution from iron ore processing a key part of efforts to avoid further climate change. To that end, recent efforts have focused on developing greener steel—higher-value steel made by removing impurities without using processes that cause carbon dioxide emissions, leaving behind high-purity steel. Global efforts to reduce carbon dioxide emissions by adopting hydrogen-based steelmaking using blast furnaces and direct reduction iron plants, followed by electric arc furnaces, to replace fossil fuels require pellets made from high-grade iron ore with low impurity content.

[0016] Limited quantities of high-grade ore are currently mined, mostly in North and South America, Europe, and the Middle East. As supplies of high-grade ore are depleted, utilization of lower-grade ore will become necessary. Countries already mining lower-grade ore will need to further refine the crude product to make it suitable for reduction with hydrogen in blast furnaces or direct reduced iron plants in order to compete with suppliers of high-grade ore and meet the expectations of international ore processors.

[0017] For many years, Australia has relied on direct shipment ore, that is, ore that can be simply mined and exported without further processing or with very limited processing (such as blending or drying). The three main types of iron ore produced in Australia are hematite, goethite, and magnetite. Hematite / goethite crude ore is high-grade and deposits are declining, while magnetite deposits are extensive and relatively low-grade, but can be used to produce very high-grade concentrate.

[0018] Iron ore mining is a high-volume, low-margin business. Iron ore mining is capital-intensive and requires significant investment in infrastructure. Producers must obtain the highest possible returns from their product, and returns are highly dependent on the grade and demand for the iron ore. Over the past decade, premiums for high-grade ore and discounts for low-grade ore have increased, and steelmakers are demanding higher-grade ore with fewer impurities.

[0019] The grade of Australian iron ore has declined in recent years, and miners are experiencing significant depletion of reserves. To compete with other iron ore producers, Australia must develop options for producing higher-grade iron ore and its derivatives.

[0020] Various routes to producing environmentally friendly iron have been evaluated, including electrochemical conversion of iron ore to iron over a wide range of temperatures (60–2,000°C) without coal, natural gas, or other reductants, using environmentally friendly hydrogen as an environmentally friendly reductant in the blast furnace of a DRI plant to replace fossil fuel-based reductants. However, making environmentally friendly processes economically viable and efficient has proven challenging. Environmentally friendly pyrometallurgical processes also rely on a stable, continuous supply of sufficient electricity, which can be difficult to supply to remote mining areas where raw ore is processed due to the highly intermittent nature of wind and solar power.

[0021] [Summary of the Invention] It is an object of the present invention to provide a method for the conversion and extraction of ores.

[0022] Another object of the present invention is to provide an environmentally friendly process, or at least a process that facilitates environmentally friendly processing of ores.

[0023] A further object of the present invention is to ameliorate at least one of the disadvantages associated with the related art.

[0024] It is an object of the embodiments described herein to overcome or ameliorate at least one of the above-mentioned drawbacks of related art mechanisms, or at least to provide a useful alternative to related art mechanisms.

[0025] In a first aspect of the embodiments described herein, there is provided a method for producing an ore concentrate solution, the method comprising contacting an ore with one or more metal bases, preferably alkali metal or alkaline earth bases, at an elevated temperature. Preferably, the ore concentrate solution is suitable for downstream beneficiation processes, such as extractive metallurgy.

[0026] The ore fed to the process of the present invention is typically crude ore, but may also be ore that has undergone some refinement to produce a concentrate. Once the ore has been treated according to the method of the present invention to obtain an ore concentrate solution, the ore concentrate solution can be fed directly to downstream processes, such as electrometallurgical extraction processes, thereby avoiding traditional beneficiation processes that are inefficient in terms of energy consumption, such as flotation, electrostatic separation, or magnetic separation and deliquoring.

[0027] Typically, the ore used in the present invention is any crude ore or ore concentrate containing a metal or metalloid. Preferably, the ore is selected from iron ores such as hematite, goethite, magnetite, titanomagnetite, and pisolite iron ore; aluminum-containing ores such as bauxite, cryolite, and corundum; gold ores such as gold-polysulfide, gold-quartz, gold-telluride, gold-tetradymite, gold-antimony, gold-bismuth-sulfonate, gold-pyrrhotine, and gold-smeltite; manganese-containing ores such as romanechite, manganite, hemimanganite, and rhodochrosite; galena, cerussite. and sulphurite; zinc ores such as hemimorphite and smithsonite; cobalt-bearing ores; uranium-bearing ores; copper-bearing ores such as copper pyrite, chalcopyrite, bornite, covellite, chalcocite, malachite, cuprite, and chalcocite; nickel-bearing ores such as laterite and magmatic sulfide deposits; silver-bearing ores such as argillite; tin-bearing ores such as cassiterite, cassiterite, sphalerite, or cylindrical cassiterite; and quartz. In a particularly preferred embodiment, the ore is an iron ore particularly rich in iron oxide, especially in the form of magnetite (FeO), hematite (FeO), goethite (FeO(OH)), limonite (FeO(OH)·n(HO)), or siderite (FeCO).

[0028] In another preferred embodiment, the ore is an ore concentrate containing species such as nickel oxide, nickel hydroxide, or nickel sulfide.

[0029] In a further preferred embodiment, the ore is an ore concentrate containing species such as copper sulfide or copper-iron sulfide.

[0030] The hot metal base or bases comprise a super-alkaline medium. Upon contact with the metal base, the ore completely or partially dissolves and / or metal-containing components are chemically converted to dissolvable species. Without wishing to be bound by theory, it is believed that, for example, sulfide ores are converted to oxides.

[0031] The additional compounds can enhance the dissolution or chemical conversion of the ore, and in particular the addition of silicates can enhance the dissolution or chemical conversion of the ore, especially the ore concentrate.

[0032] Alkali metal or alkaline earth bases suitable for use in the present invention are preferably hydroxides, although other bases such as metal oxides or metal ammonium species may also be used.

[0033] Typically, the metal base is selected from alkali metal bases such as lithium, sodium, potassium, rubidium, or cesium hydroxides, or alkaline earth bases such as calcium, barium, or strontium hydroxides. In particularly preferred embodiments, the metal base is selected from lithium hydroxide, sodium hydroxide, potassium hydroxide, or calcium hydroxide. In particularly preferred embodiments, the superalkaline medium comprises 45 wt % to 100 wt % sodium hydroxide and / or potassium hydroxide.

[0034] One or more metal bases may be contacted with the ore, and the combination of metal bases may be in the form of a eutectic mixture. A eutectic mixture of sodium hydroxide, potassium hydroxide, and / or lithium hydroxide is particularly preferred. In some embodiments, NaOH is preferred for economic reasons, although pure NaOH may not be as efficient as the combination of NaOH and KOH, which forms a eutectic system.

[0035] The superalkaline medium comprising an alkali metal or alkaline earth base contacts the ore at an elevated temperature, preferably above 160° C., or above 200° C., preferably above 250° C., more preferably above 300° C. In a particularly preferred embodiment, the alkali metal or alkaline earth base contacts the ore at a temperature of from 160° C. to 400° C., preferably from 200° C. to 350° C., more preferably from 250° C. to 350° C.

[0036] For example, with regard to eutectic mixtures, most mixtures of NaOH and KOH have a lower melting point than the compounds of the constituent elements. For a 1:1 molar ratio of NaOH:KOH, the eutectic mixture forms at 170°C. If absorbed water or water of crystallization is present, for example in a 1:1:1 ratio of NaOH:KOH:HO, the temperature at which the eutectic mixture forms may be below 100°C.

[0037] Once the superalkaline medium has contacted the ore, the ore is partially or completely dissolved and the mixture is cooled to produce a solid which may then be reheated for further processing.

[0038] Molten metal bases, particularly molten hydroxides, often contain impurities such as water. Preferably, the metal base incorporated into the superalkaline medium of the present invention contains no more than one mole of water per mole of hydroxide. Water can also be removed from the superalkaline medium by briefly heating the medium to higher temperatures (e.g., 450°C or higher). Subsequent use of an inert gas shield over the superalkaline medium can limit or prevent water reabsorption.

[0039] The metal bases used in the present invention may contain small amounts of chemical impurities, for example, sodium hydroxide may generate or contain small amounts of sodium carbonate (Na2(CO3)).

[0040] In a second aspect of the embodiments described herein, there is provided a method of refining ore, the method comprising: (i) contacting the ore with one or more metal bases, preferably alkali metal or alkaline earth bases, at elevated temperatures; (ii) sending the solution produced in step (i) to a mineral processing process; Includes:

[0041] In one embodiment of the invention, the beneficiation process may be, for example, an extraction process that removes silica and / or alumina, or other impurities including titania, phosphorus, and manganese.

[0042] In another aspect of the invention, the beneficiation process may be, for example, an extractive metallurgical process, preferably electrometallurgical, in which metals are precipitated from solution.

[0043] Upon contacting the ore with one or more metal bases, the ore may be completely or partially dissolved, or constituent moieties within the ore may be chemically converted to dissolvable species. Ultimately, the solution thus produced may be sent to downstream extractive metallurgical processing, such as an electrochemical process for selective electrodeposition of target metals, although it may be advantageous to include steps to enhance the extraction of certain elements, such as nickel, cobalt, molybdenum, lithium, aluminum, and silicon. The solution may also be subjected to further beneficiation processes.

[0044] Thus, in a third aspect of the embodiments described herein, there is provided a method of beneficiating ore, the method comprising: (i) contacting the ore with one or more metal bases, preferably alkali metal or alkaline earth bases, at elevated temperatures to produce an ore concentrate solution; (ii) extracting one or more components of the ore from the ore concentrate solution; Optionally, (iii) sending the extracted solution to an extractive metallurgy process, preferably electrometallurgy, to deposit metal; Optionally, (iv) passing the extracted ore concentrate solution to further beneficiation steps; Includes:

[0045] In a fourth aspect of the embodiments described herein, there is provided a method of beneficiating ore, the method comprising: (i) contacting the ore with one or more metal bases, preferably alkali metal or alkaline earth bases, at elevated temperatures; (ii) converting sulfide species in the ore to oxides in a solution; (iii) extracting one or more of the oxides from the solution; Optionally, (iii) subjecting the extracted oxides to further refining steps; Includes:

[0046] In a fifth aspect of the embodiments described herein, there is provided a method of beneficiating ore, the method comprising: (i) contacting the ore with one or more metal bases, preferably alkali metal or alkaline earth bases, at elevated temperatures; (ii) producing a solution containing dissolved components from the ore; (iii) removing the components from the solution; Optionally, (iv) sending the purified solution from step (iii) to a downstream mineral processing step; Includes:

[0047] The components removed from the solution may include aluminum and silicate species. The components removed from the solution may be valuable commercial products such as geopolymers (inorganic aluminosilicate polymers) and zeolites (generally M n+ 1 / 2 (AlO2) - (SiO2) x yH2O, where M n+ 1 / 2 is a metal ion, typically Na + , K. + , Ca 2+ , Mg 2+ , or H + ) which is

[0048] In another aspect, the present invention provides a concentrated ore or refined ore produced according to the method of the present invention.

[0049] In yet another aspect, the present invention provides a commercial product produced according to the method of the present invention. In a particularly preferred embodiment, the commercial product is a metal.

[0050] Other aspects and preferred embodiments are disclosed herein and / or defined in the appended claims, which form part of the description of the invention.

[0051] In essence, embodiments of the present invention stem from the realization that ores, including crude ores, can be converted into useful concentrate ores or commercially valuable chemical products using a super-alkaline medium.

[0052] The advantages provided by the process of the present invention include the following: -It must be possible to carry out the operation at normal pressure. Low energy consumption. Highly efficient conversion of ores into valuable chemical species. - To refine ores, especially crude ores, with high efficiency. · Supplying ore feed material to further downstream ore refining processes. · To provide chemical species suitable for processing into valuable chemical products.

[0053] Further areas of applicability of embodiments of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various modifications and improvements within the spirit and scope of the disclosure herein will be apparent to those skilled in the art from this detailed description.

[0054] Further disclosure, objects, advantages, and aspects of the preferred and other embodiments of the present application can be better understood by those skilled in the relevant art by reference to the following description of each embodiment taken in conjunction with the accompanying drawings, which are provided for illustrative purposes only and are therefore not intended to limit the disclosure herein. [Brief explanation of the drawings]

[0055] [Figure 1] FIG. 1 illustrates the use of molten hydroxide as a superalkaline medium at different temperatures. [Figure 2]Figure 2 is a graph illustrating the deposition of iron from solutions produced by contacting hematite with a NaOH / KOH eutectic mixture at five temperatures: 250°C, 275°C, 300°C, 325°C, and 350°C. The graph records current (I) in mA versus voltage (E) in volts. [Figure 3] Figure 3 is a graph illustrating the effectiveness of removing water from a super-alkaline medium. The graph records current (I) in mA versus voltage (E) in volts. DETAILED DESCRIPTION OF THE INVENTION

[0056] [Detailed Description of the Invention] The present invention provides a method for refining ore, e.g., crude ore ore concentrate, for downstream processing, particularly extractive metallurgy. The method includes contacting the ore with a superalkaline medium at elevated temperature, formed from one or more metal bases, preferably alkali metal and / or alkaline earth bases. When two or more alkali metal and / or alkaline earth bases are used, the superalkaline medium is typically in the form of a eutectic mixture.

[0057] Figure 1 illustrates the use of molten hydroxide as a superalkaline medium at different temperatures. At lower temperatures, around 100°C, the superalkaline medium is particularly useful for dissolving species such as silica and alumina from ore. The concentrate ore may be sent to other mineral processing steps, and the alumina or silica may be used as a valuable product. At intermediate temperatures, around 200°C, the superalkaline medium is particularly useful for dissolving certain metal oxides that can be recovered by electrowinning from the solution. At higher temperatures, around 300°C, the superalkaline medium is particularly useful for dissolving metal oxides, such as iron, that can be recovered by electrowinning from the concentrate ore.

[0058] In particular, the super-alkaline medium can be used to: Complete or partial dissolution or chemical conversion of iron-bearing ores into soluble species followed by electrochemical deposition of the metal from this solution. Complete or partial dissolution of ores or chemical conversion into soluble species that facilitate the extraction of specific elements (e.g., nickel, cobalt, molybdenum, aluminum, lithium, and silicon) followed by selective electrolytic deposition of the elements from molten hydroxides or chemical treatment of the dissolved elements. The complete or partial conversion of sulfide ores or concentrates (e.g., iron or nickel) to oxides, followed by conventional processing of these oxides (chemical and / or electrochemical, but not necessarily in molten hydroxide). Partial dissolution of mineral ores to remove components (e.g. alumina and silica) followed by downstream processing of the refined ore and the potential conversion of the removed components into commercial products such as geopolymers and zeolites.

[0059] <Ore concentrate> In any of the above processes, additional compounds may be used to promote dissolution of the ore or chemical conversion of components to soluble species. In particular, the addition of silicates may enhance the conversion of solid oxides to metal-silicates that produce solutions with superalkaline media. For example, the addition of silicates such as quartz, feldspar, mica, amphibole, pyroxene, olivine, or aluminum-silicates may be particularly effective for ore concentrates.

[0060] When an ore concentrate is first exposed to a molten hydroxide, it can produce a solid metal oxide. For example, a nickel hydroxide or nickel sulfide concentrate can initially produce a solid iron-nickel oxide. This solid oxide may also contain small amounts of other elements, such as iron, manganese, magnesium, copper, and cobalt (but only in small amounts of silicates).

[0061] By controlling process parameters such as temperature and silica concentration, it is possible to selectively dissolve metals contained in the solid oxide, while undesired oxides remain in the solid oxide, allowing control of purity and species in the solution.

[0062] The metal may be electrolytically deposited directly from the solution or may be isolated downstream by conventional techniques (eg, neutralization followed by conventional electrowinning).

[0063] In the case of sulfide concentrates, this procedure is particularly effective as it eliminates the need for the traditional high temperature "baking" step. [Example]

[0064] The present invention will now be further described with reference to the following non-limiting examples.

[0065] Example 1 - Hematite The method of the present invention was applied to a sample of iron ore "dust" from Western Australia containing about 24 wt% Si, about 21 wt% Fe, and 1 wt% Ni.

[0066] A superalkaline medium containing a 1:1 molar NaOH / KOH eutectic mixture was produced at 200 °C. No attempt was made to remove water from the eutectic mixture, and the equilibrium water content at this temperature is known to be 8–10 wt% depending on the NaOH:KOH ratio. Upon contacting the superalkaline medium with iron ore dust, a solution containing aluminates, silicates, and several iron oxides (magnetite, hematite, goethite, limonite, and siderite) was immediately produced. However, at 200 °C, the majority of the iron oxides remained in the solid state. The concentration of iron oxide species in the solution increased with increasing temperature, which reduced the water content at atmospheric pressure, until complete dissolution was achieved at 350 °C.

[0067] The hematite was recovered from the solution at 200°C by simple decantation of the liquid followed by washing with water. Analysis showed that the hematite had a purity of 93 wt% (61% iron), which is considered "export grade".

[0068] Example 2 - Nickel The solution produced in Example 1 was maintained at 200°C and atmospheric pressure and fed to an electrolytic cell in an electrowinning process. The solution contained nickel derived from approximately 1% of the nickel contained in the original ore.

[0069] In the electroplating process, a current was passed through the solution from an inert gold anode in a ratio of 7:1 (Ni:Fe), depositing nickel and iron onto the cathode.

[0070] Example 3 - Ore Dissolution in Molten Hydroxide A superalkaline medium containing a 1:1 molar NaOH / KOH eutectic mixture was prepared at 300°C. Hematite was gradually added to form a solution. At low concentrations of hematite, the solution was pale green and became darker in color. At a concentration of 200 g hematite per liter of superalkaline medium at 300°C, the solution was dark green / black.

[0071] Ores of different qualities with Fe contents ranging from 48% to 62% were similarly tested and all showed the same dissolution behavior.

[0072] The resulting solution exhibited low viscosity above about 250°C (likely behaving similarly to water), which is particularly suitable for electrochemical processes. The solution was cooled to 25°C, at which point it became a solid. This solid material could be remelted and subjected to further metallurgical extraction.

[0073] The high concentration of hematite in the ultra-alkaline medium produced a solution in the precipitate. When the solution was cooled to 25 °C and then remelted, the precipitate remained an amorphous solid and did not dissolve or melt, even when exposed to temperatures up to 300 °C.

[0074] Hematite and goethite are both iron oxides in which iron is in the oxidation state (III), giving the ores their characteristic red "rust" to reddish-brown color. The appearance of the distinctive green color indicates that at least some of the iron (III) changed oxidation state during solution formation. Without wishing to be bound by theory, the green color of the solution may be due to the following: - formation of soluble iron(II) silicates; and / or - the formation of a "verdigris" which is a mixed-valence (oxy)hydroxide with iron in mixed oxidation states (+2 and +3). In low-melting iron silicates, both Fe(II) and Fe(III) species are present, and only Fe(II) silicates are green; and / or -The formation of other iron compounds in solution.

[0075] The observed conversion to Fe(II) is supported by several viable reaction schemes, all of which suggest the evolution of oxygen, which is consistent with the observed gas bubbles when superalkaline media contacts the ore according to the following reaction scheme: 2Fe2O3 + 4NaOH → 4(Na + ,HFeO2 - )+O2 Fe2O3 + 2NaOH → H2O + O2 + 2FeO + 2Na (Sodium reacts with water to produce NaOH and H2. FeO is soluble in alkaline media.) 2Fe2O3 → 4FeO+O2 2Fe2O3 + 2H2O → 4FeOOH, then 4FeOOH + 2H2O → 4Fe(OH)2 + O2

[0076] Oxygen generation may be useful for novel applications, such as mining or smelting minerals in anaerobic or oxygen-deficient atmospheres, which could facilitate mineral resource extraction on planets such as the Moon, asteroids, or Mars.

[0077] Example 4 - Effect of temperature on iron precipitation In the electrowinning process held at atmospheric pressure, the solution of Example 3 was divided and fed to an electrolytic cell, where deposition was carried out at temperatures of 250°C, 275°C, 300°C, 325°C, and 350°C, respectively.

[0078] In the electroplating process, a current was passed through the solution from an inert gold anode, and iron was deposited onto an iron cathode, with parasitic hydrogen evolution occurring during the deposition process.

[0079] Figure 2 is a graph illustrating the deposition results of iron from each solution. The graph shows that deposition was successful at 250°C, with the deposition rate increasing with increasing temperature. The increase in current with increasing temperature accounts for both the decrease in viscosity of the solution and the increase in normal activity.

[0080] Example 5 - Effect of water in ultra-alkaline media Many alkali metal or alkaline earth bases are hygroscopic. Hydroxides in particular are very hygroscopic, and even commercially available "pure" hydroxides often contain up to 10 wt% water at 200°C.

[0081] The presence of water in electrochemical processes such as electrodeposition can lead to parasitic hydrogen generation due to water decomposition. This side reaction reduces the overall efficiency of the electrodeposition reaction. Water removal is important for metal deposition, especially iron deposition, because the thermodynamic reduction potential between water and iron oxide favors hydrogen generation over iron deposition.

[0082] Water can be effectively removed by briefly heating the superalkaline medium to higher temperatures (e.g., above 450°C). An inert gas shield must then be maintained over the solution during precipitation to limit or prevent water reabsorption. Also, prolonged heating of the solution above 350°C during precipitation removes enough water to nearly eliminate hydrogen evolution.

[0083] Figure 3 is a graph illustrating the effect of removing water from a super-alkaline medium. The graph records current (I) in mA against voltage (E) in volts. The first plot was plotted at 12:00 PM, the second at 2:00 PM, the third at 4:00 PM, and the final at 4:30 PM. The increase in the slope of the graph at 4:00 PM, at approximately -2.2 volts, occurs as water is removed from the super-alkaline medium. Overall, the graph shows that prolonged heating at 350°C is successful in removing water, although the process is fairly slow. The graph also reflects the "real" iron deposition rate.

[0084] Example 6 - Dissolution / conversion of iron ore as a function of impurities Three dried hematite samples (dried at 200°C for 2 hours) from the same Pilbara source but with different iron contents (55%, 60%, and 62% Fe, respectively) were reacted with molten hydroxide in three Teflon-lined vessels (Teflon is a registered trademark).

[0085] A 20 g portion of each ore sample was added to 48 g of 1:1 (molar) NaOH:KOH at 310°C and stirred for 1 minute, resulting in the development of a dark green solution. The temperature was held at 310°C for 4 hours, after which the samples were covered with Teflon lids and allowed to cool to room temperature.

[0086] To determine ore dissolution / conversion, Teflon liners containing ore / hydroxide samples were immersed in 150 mL of 5.5 M HCl and reacted with stirring for 24 hours. The liquid was then decanted, and 50 mL of fresh 5.5 M HCl was added and reacted for 2 hours, then decanted again. The unreacted ore was then washed three times with distilled water, dried in air at 150 °C, and weighed. The characteristics of each sample are listed in Table 1.

[0087] [Table 1]

[0088] From Table 1, we can see that the saturation of dissolved ore in the molten hydroxide increases with increasing amounts of impurities in the ore. This is not unexpected, as the main impurities, silica and alumina, are well known to dissolve readily under alkaline conditions. However, the increase in dissolved ore is greater than the amount of additional impurities, such as when the Fe content increases from 62% to 60% and then to 55%. This suggests that the impurities aid in the dissolution of iron oxide in the molten hydroxide.

[0089] Two control experiments were performed using a 60% Fe ore sample. In one experiment, the reaction time at 310°C was reduced from 4 hours to 1 hour. As a result, the measured saturation of the dissolved ore remained unchanged, strongly suggesting that the reaction / conversion time was well below 1 hour under the conditions used.

[0090] In another experiment, 20 g of 60% Fe ore was reacted with 200 mL of 5.5 M HCl for 26 hours. The undissolved ore was washed with water, dried, and weighed. Exposure to HCl resulted in only a slight loss in weight (see Table 1), indicating that the effect seen from exposure to molten hydroxide is caused by the hydroxide and not by titration with HCl.

[0091] Example 7 - Dissolution of Manganese(IV) Oxide (MnO) Manganese oxide is a common impurity present in Australian iron ore, typically with an upper limit of approximately 1%. The manganese impurity rarely becomes part of the iron oxide lattice, but rather appears as well-defined MnO2 grains. The low abundance of manganese oxide in the ore makes it difficult to determine what happens to it during the ore dissolution process. To address this, 5 wt% synthetic MnO2 was added to a 1:1 (molar) NaOH:KOH mixture at 300 °C. The molten hydroxide immediately turned black and gradually discolored to a dark green / black color after 24 hours, with no precipitate. Based on the color observed at this temperature, it is unlikely that manganese(II) hydroxide was formed, as manganese(II) hydroxide is white and decomposes at temperatures up to 140 °C. Instead, the green color indicates the partial formation of manganate(VI) ions.

[0092] Electrodeposition from a molten hydroxide solution was attempted at 300 °C under conditions known to produce iron from dissolved iron ore. Nickel foil was used as both the anode and cathode material, and a voltage of 1.8 V was applied between the electrodes. A bright green solution was produced around the anode, indicating the formation of manganate as an oxidation product. Analysis of the deposit on the cathode revealed it to be a mixture of manganese oxides, with the manganese being primarily in the divalent (+2) and tetravalent (+4) oxidation states.

[0093] This experiment demonstrates that under the conditions used to electrolytically deposit dissolved iron species, metallic manganese cannot be deposited as a cathodic product (either as pure manganese or as an alloying element). Rather, trace impurities of manganese oxide are suspected.

[0094] Example 8 - Dissolution of molten hydroxides and subsequent separation at high temperature In a heated laboratory-scale thickener, sodium hydroxide (250 g) was melted at 335°C and 25 g of dry (400°C) iron ore powder was added. One hour after the ore had dissolved, the temperature was increased to 370°C and held at this temperature for one hour. This increase in temperature caused the dissolved iron species to phase separate from the bulk molten hydroxide within the conical portion of the thickener by dehydrogenation. This allowed the iron-rich intermediate to be removed from the thickener by gravimetric means.

[0095] The main impurities from the ore (silica and alumina) remained dissolved as silicates and aluminates in the molten hydroxide. The process could be repeated by lowering the temperature to 335°C, adding more iron ore, and raising the temperature again to 370°C to isolate a more iron-bearing intermediate.

[0096] The iron-rich intermediate was added to a eutectic melt of sodium hydroxide and potassium hydroxide, and electrodeposition was carried out at temperatures ranging from 220 to 310°C.

[0097] Dissolution and separation can also be carried out directly in the hot eutectic melt, but this incurs additional costs as expensive potassium hydroxide is consumed in the process by conversion to potassium silicate and potassium aluminate.

[0098] Example 9 - Dissolution of iron ore in a molten hydroxide eutectic mixture followed by removal of impurities from the surface Four kilograms of hydroxide eutectic mixture (1:1 NaOH:KOH by weight) was heated to 300°C in a vertical furnace with a nickel liner. A 400g sample of dried iron ore (hematite, 55% Fe) was added and stirred for 30 minutes until all the iron ore was dissolved. The stirring was then stopped and the temperature was gradually and slowly reduced.

[0099] At temperatures close to the freezing point of the mixture (210-230°C), a liquid-liquid gravimetric phase separation occurred. The lower phase contained heavier, iron-rich species, while the upper phase contained impure species (mainly silicates and aluminates). This impure phase could be removed by carefully skimming off the upper layer of the solution.

[0100] Further reduction in temperature (to 200 °C) resulted in the formation of a white crust on the surface of the solution, which was removed by simple mechanical means. Elemental analysis revealed that this crust contained up to 50% impurities in a hydroxide matrix.

[0101] Both of these methods of separating liquid or solid impurities from molten ore provide a practical method of beneficiation prior to further processing, for example by electrowinning, to an iron-rich solution.

[0102] Example 10 - Magnetite concentrate A 10 wt% sample of magnetite concentrate (67% iron, 5% silica, particle size 50 μm or less) was added to a molten mixture of NaOH and KOH (molarity 3:1) at 310°C. The magnetite concentrate dissolved rapidly under stirring to produce a dark brown solution. This solution was used for iron electrowinning at 310°C without further treatment.

[0103] The experiment was repeated with a 1:1 (molar) ratio of NaOH:KOH and the magnetite concentrate was melted at 310° C. After melting was complete, the temperature was reduced to 240° C., followed by iron electrowinning.

[0104] Example 11 - Silica, Silicates, and Quartz Silica and other SiO2-based modifications are known to dissolve readily in alkaline media, which is an important aspect of various established routes for industrial-scale processing of, for example, bauxite and spodumene minerals. However, these methods are based on the use of hydroxide solutions rather than molten hydroxides.

[0105] When 10 wt% silica or sodium silicate powder was added to a molten hydroxide eutectic mixture (1:1 NaOH:KOH) at 310°C, the silica or sodium silicate immediately began to react with the hydroxide, releasing water as part of the reaction. The release and evaporation of water cooled the top of the molten hydroxide below the melting temperature. This resulted in the formation of a solidified sponge-like mass on top of the molten hydroxide, which stalled further reaction of the silica due to its poor thermal conductivity. To overcome this problem, the silica was slowly added to the molten hydroxide over a 48-hour period, resulting in a clear, transparent solution.

[0106] The reaction of quartz with molten hydroxide, while having the same overall chemistry as silica, is significantly slower and does not present the same problems as forming a sponge-like crust / matrix. In fact, this allows quartz leaching to be easily integrated into a (silica) dissolution-electrowinning circuit.

[0107] Example 12 - Nickel sulfide ore and concentrate A sample of nickel sulfide ore from Western Australia (2.0% Ni, 14.1% Fe, 0.2% Cu, 6.3% S, 9.9% MgO) with a particle size less than 3 mm was added to a 1:1 NaOH:KOH eutectic melt (6 wt% ore, 94 wt% hydroxide) at 250°C. The ore began to dissolve immediately and was completely dissolved after 3 minutes, transforming the clear molten hydroxide into an orange / brown solution.

[0108] In electrowinning experiments, dissolved ore solutions were used as electrolytes, and magnetic deposits were achieved at potentials as low as 1.4 V. When the magnetic deposits were washed with water and then immersed in 5.5 M HCl, hydrogen evolution was detected, confirming their metallic nature.

[0109] Example 13 - Nickel sulfide ore and concentrate A nickel sulfide concentrate sample from Western Australian nickel sulfide ore (13.6% Ni, 38.7% Fe, 1.1% Cu, 32.8% S, 3.5% MgO) with particle size less than 1 mm was added to a 1:1 NaOH:KOH eutectic melt (3 wt% concentrate, 97 wt% hydroxide) at 250°C. The concentrate rapidly dissolved in the molten hydroxide within 2 minutes, producing a deep reddish-brown solution. Dissolution occurred without evolution of gas or vapor. The solution was then capped with a Teflon lid and left at 250°C for 24 hours. After 24 hours, no precipitation was observed and the color remained unchanged, although it had increased in intensity.

[0110] The dissolved concentrate solution was then used in electrowinning experiments. Electrochemical current flow was observed to begin already at a cell voltage of 0.6 V, reach a low-current plateau at 0.9 V, and then rapidly increase again at 1.2 V. Cathodic deposition at 1.0 V resulted in the formation of a thin film with a discernible copper color, indicating that copper could be selectively deposited from the solution, although the current density was limited by the diffusion of low-concentration copper species in the solution.

[0111] Cathodic deposits from the same solution obtained at cell voltages of 1.6 and 1.8 V were magnetic and evolved hydrogen when exposed to dilute HCl solution. In particular, at 1.8 V, the cell voltage was 200 mA / cm 2 Current densities exceeding 0.1 were measured, indicating very high diffusivities of dissolved metal species in molten hydroxide solutions.

[0112] It has been confirmed that the copper, nickel, and iron in sulfide ores and concentrates are contained within sulfide structures, and that the sulfide bonding structure is broken during dissolution by electrolytic deposition from molten hydroxide solutions. Therefore, it is expected that other sulfide ores, such as copper-iron sulfide ores such as chalcopyrite and their concentrates, will undergo a similar dissolution process in molten hydroxides.

[0113] It is worth noting that while iron exists only in the divalent (+2) oxidation state in sulfide ores, in most commercial oxides all of the iron (hematite and goethite) or most of the iron (magnetite) is in the trivalent (+3) oxidation state. From an electroreduction perspective, this means that the current / energy required to reduce iron from sulfide structures is significantly less than from oxides.

[0114] While the invention has been described in relation to particular embodiments thereof, it will be understood that the invention is capable of further modifications. This application is intended to cover any modified uses or applications of the invention in general accordance with the principles of the invention and including departures from the present disclosure as applicable to the essential features described hereinabove and within the scope of known or customary practice within the art to which the invention pertains.

[0115] Since the present invention can be embodied in several forms without departing from the spirit of its essential characteristics, it should be understood that the above-described embodiments are not intended to limit the present invention unless otherwise specified, but rather should be broadly construed as falling within the spirit and scope of the present invention as defined in the appended claims. The described embodiments are to be considered in all respects only as illustrative and not restrictive.

[0116] Various modifications and equivalent arrangements are intended to fall within the spirit and scope of the present invention and the appended claims. Accordingly, the specific embodiments are to be understood as illustrative of the many ways in which the principles of the invention may be practiced. In the following claims, means-plus-function clauses are intended to cover structures that perform the defined function and to cover not only equivalent structures but also equivalent structures.

[0117] When a Markush group or other grouping is used herein, all individual members of the group, and all possible combinations and subcombinations of the group members, are intended to be included individually in the disclosure. Any combination of the components described or exemplified herein can be used to practice the invention, unless otherwise indicated.

[0118] Whenever a range is given herein, e.g., a temperature range, a time range, or a composition or concentration range, all intermediate ranges and subranges, as well as all individual values ​​within that given range, are intended to be included within the present disclosure. It will be understood that any subrange or individual value within a range or subrange described herein may be excluded from the claims herein.

[0119] As used herein, "comprising" is synonymous with "including," "containing," or "characterized by" and is an inclusive or open-ended term that does not exclude additional, unrecited elements or method steps. As used herein, "consisting of" excludes any element, step, or ingredient not recited in the claim element. As used herein, "consisting essentially of" does not exclude materials or steps that do not affect the basic and novel characteristics of the claim. The broad term "comprising" is intended to encompass the narrower definition of "consisting essentially of" and the even narrower definition of "consisting of." Thus, any recitation herein of the phrase "comprising one or more claim elements" (e.g., "comprising A") is intended to encompass the narrower definitions of "consisting essentially of A" and "consisting of A," etc. Thus, the broader term "comprising" provides specific support for the use of either "consisting essentially of" or "consisting of," respectively. The invention illustratively described herein suitably can be practiced in the absence of one or more elements or limitation not specifically disclosed herein.

[0120] Those skilled in the art will understand that materials and methods other than those specifically exemplified can be used in the practice of the present invention without the exercise of undue experimentation. All functional equivalents known in the art of any such materials and methods are intended to be encompassed by this invention. The terms and expressions used are used as terms of description and not of limitation. The use of such terms and expressions is not intended to exclude equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention as claimed. Thus, while the present invention has been specifically disclosed by examples, preferred embodiments, and optional features, it is understood that modifications and variations of the concepts disclosed herein may be adopted by those skilled in the art, and that such modifications and variations are deemed to be within the scope of the invention as defined by the appended claims.

[0121] Each reference cited herein is incorporated herein by reference in its entirety. Such references may provide sources of materials, alternative materials, details of methods, and additional uses of the present invention.

Claims

1. 1. A method for providing an ore concentrate solution suitable for mineral processing, comprising: A method comprising contacting the ore with one or more metal bases at 160°C to 400°C.

2. 10. The method of claim 1, The method, wherein the one or more metal bases are alkali metal bases or alkaline earth bases.

3. The method according to claim 2, the alkali metal base is selected from lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, or cesium hydroxide; The alkaline earth base is selected from calcium hydroxide, barium hydroxide, or strontium hydroxide.

4. 10. The method of claim 1, The method of claim 1, wherein the one or more metal bases at 160°C to 400°C constitute a super-alkaline medium that partially or completely dissolves the ore.

5. 10. The method of claim 1, The method of claim 1, wherein the one or more metal bases at 160°C to 400°C comprise a super-alkaline medium comprising 45 wt% to 100 wt% sodium hydroxide and / or potassium hydroxide.

6. 10. The method of claim 1, The method of claim 1, wherein the one or more metal bases are heated at a temperature of from 200°C to 350°C.

7. The method of claim 1, The method of claim 1, wherein the one or more metal bases are heated at a temperature of from 250°C to 350°C.

8. 10. The method of claim 1, 10. The method of claim 1, wherein the ore is selected from the group comprising one or more of iron ore, aluminum-bearing ore, gold ore, manganese-bearing ore, lead ore, cobalt-bearing ore, uranium-bearing ore, copper-bearing ore, nickel-bearing ore, silver-bearing ore, tin-bearing ore, silica ore, and quartz.

9. The method of claim 1, The method, wherein the ore is selected from one or more of hematite, magnetite, or goethite.

10. 10. The method of claim 1, The method further comprising adding silicate to the combination of the ore and the one or more metal bases at 160°C to 400°C.

11. 10. The method of claim 1, the one or more metal bases at 160°C to 400°C constitute a super-alkaline medium; The method of claim 1, wherein the super-alkaline medium is subjected to heating at a temperature of 450° C. or above for a short period of time to remove water.

12. 10. The method of claim 1, The ore concentrate is sent to a mineral processing step.

13. The method of claim 1, The ore concentrate is sent to an extractive metallurgical process.

14. 10. The method of claim 1, The method further comprises subjecting the ore concentrate to a step of extracting one or more components of the ore from the ore concentrate solution.

15. The method of claim 14, The method further comprises subjecting the ore concentrate to an extractive metallurgical process for metal precipitation.

16. The method of claim 14, The method further comprises subjecting the ore concentrate to a step of subjecting the extracted ore concentrate solution to a further beneficiation process.

17. 10. The method of claim 1, The ore concentrate further comprises: generating a solution containing dissolved components from the ore concentrate; removing the components from the ore concentrate solution; The method by which this is applied.

18. The method of claim 17, The method further comprises subjecting the ore concentrate to a step of passing the purified solution to a downstream beneficiation process.

19. 12. A concentrated ore produced according to the method of any one of claims 1 to 11.

20. 19. Metals recovered by the beneficiation step of any one of claims 12 to 18.

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