Ore treatment method

Abstract

The present invention relates to a method of providing a concentrate solution suitable for use in a beneficiation process, the method comprising the step of contacting the ore with one or more metal bases at an elevated temperature. The one or more metal bases may form an ultra-alkaline medium that partially or fully dissolves the ore at elevated temperatures. 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 an alkaline earth metal base, preferably selected from calcium hydroxide, barium hydroxide or strontium hydroxide. The one or more metal bases may form an ultra-alkaline medium that partially or fully dissolves the ore at elevated temperatures.

Description

Technical Field

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

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

[0003] In another aspect, the present invention is applicable to providing processed ores for downstream ore dressing processes.

[0004] In a particular aspect, the present invention is applicable to providing processed ores for downstream electrometallurgical processes such as electrodeposition or electroextraction.

[0005] For ease of description, the present invention will be described hereinafter by taking iron ore as an example. However, it should be understood that the present invention is not limited thereto, but extends to various ores and various valuable products (including metal- and metalloid-based products). In addition, although the present invention will be described in a manner convenient for description as providing processed materials for electrometallurgy, it can also be extended to other forms of extractive metallurgy and ore dressing processes. Background Art

[0006] It should be understood that any discussion of literature, devices, actions or knowledge in this specification is for the purpose of explaining the background of the present invention. In addition, the discussions throughout this specification arise from the inventors' awareness and / or the inventors' recognition of certain related technical problems. In addition, any discussion of materials (such as literature, devices, actions or knowledge) in this specification is included to explain the background of the present invention based on the inventors' knowledge and experience. Therefore, any such discussion should not be regarded as an admission that any material constituted the basis of the prior art in the relevant field in Australia or elsewhere or a part of the common general knowledge as of the priority date of the present disclosure and claims.

[0007] The term "crude ore" refers to ores, metals, metalloids, minerals and other products containing mineral substances that are mined from underground or otherwise removed and can be sized or crushed. As part of industrial processing, the crude ore is further processed or beneficiated to separate valuable minerals from waste rock or gangue. "Ore dressing" is a term that refers to any treatment that enhances or favors the economic value of an ore to provide a higher grade product (referred to as "concentrate") and a waste stream.

[0008] Further processing typically includes extractive metallurgy to remove metals from natural minerals. Extractive metallurgy techniques are generally divided into four categories: hydrometallurgy, pyrometallurgy, ion metallurgy and electrometallurgy.

[0009] Electrometallurgy involves metallurgical processes carried out in some form of electrolytic cell. The most common electrometallurgical processes are electrolytic refining and electroextraction.

[0010] Electrolytic extraction is an electrolytic process used to recover metals from aqueous solutions, usually after the ore has undergone one or more hydrometallurgical treatments. An electric current passes from an inert anode through a leaching solution containing dissolved metal ions, causing the metal to deposit on the cathode and be recovered.

[0011] Electrolytic refining uses a similar process to remove impurities from metals. In electrolytic refining, the anode consists of impure metal to be refined. The impure metal anode is oxidized and the metal dissolves into the solution. Metal ions migrate through an acidic electrolyte towards the cathode, where pure metal is deposited.

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

[0013] In addition to metals, many other commercially valuable products are derived from ores. For example, silica is an abundant and chemically complex substance present in many minerals, especially quartz. Silica is very valuable to the microelectronics, food, and pharmaceutical industries.

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

[0015] For example, the steel industry accounts for approximately 7% of global carbon dioxide emissions, and reducing carbon pollution from iron ore processing is very important for avoiding further climate change. Therefore, in recent years, there has been a focus on developing "green iron" - a higher value form of iron. The impurities in this "green iron" have been removed, leaving purer iron, and processes that produce carbon dioxide emissions are not used. The world is working to reduce carbon emissions by using blast furnaces or direct reduced iron facilities and then using hydrogen-based steelmaking in electric arc furnaces instead of fossil fuels, but high-quality iron ore pellets with low impurity content are required.

[0016] The quantity of high-grade ores currently mined is limited, mainly in the Americas, Europe, and the Middle East. As high-grade ore resources are depleted, it is necessary to mine low-grade ores. Countries that have mined low-grade ores need to further refine the crude products to make them suitable for reduction with hydrogen in blast furnaces or direct reduced iron facilities in order to compete with suppliers of high-grade ores and meet the requirements of overseas ore processors.

[0017] Australia has relied on direct shipping ores for many years, i.e., ores that can be simply mined and exported without further treatment or with very limited treatment (such as blending or drying). The three main types of Australian iron ores are hematite, goethite, and magnetite. Coarse hematite / goethite has a higher grade, and the deposits are decreasing; while magnetite deposits are larger in scale and have a relatively lower grade, but can be used to produce ultra-high-grade concentrates.

[0018] Iron ore mining is a high - volume, low - margin business. Iron ore mining is capital - intensive and requires substantial infrastructure investment. Producers must extract the best returns from their products, and the returns depend largely on iron ore grade and demand. In the past decade, the premium for high - grade ore and the discount for low - grade ore have both increased, making steel manufacturers require high - grade ore with fewer impurities.

[0019] In recent years, the grade of Australian iron ore has declined, and mining companies are experiencing significant depletion of their reserve deposits. To compete with other iron ore producers, Australia must develop technical solutions for producing higher - grade iron ore or its derivatives.

[0020] Various routes for producing green iron have been evaluated, including electrochemically converting iron ore to iron at a wide range of temperatures (60 °C to 2000 °C) without using coal, natural gas, or other reducing agents; and using green hydrogen as a green reducing agent to replace fossil - fuel - based reducing agents in the blast furnaces of DRI plants. However, it has proven difficult to make green processes economically viable and efficient. Green pyrometallurgical processes also rely on a continuous and uninterrupted supply of sufficient electricity, which may be difficult to supply in remote mining areas where crude ore is processed due to the high intermittency of wind and solar power generation. Summary of the Invention

[0021] An object of the present invention is to provide a method for the conversion and extraction of ores.

[0022] Another object of the present invention is to provide a green method, or at least a method for promoting the green treatment of ores.

[0023] Another object of the present invention is to alleviate at least one defect of the related art.

[0024] The object of the embodiments described herein is to overcome or alleviate at least one of the above - mentioned defects of the related - art systems, or at least to provide a useful alternative to the related - art systems.

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

[0026] The ore fed into the method of the present invention is typically crude ore, but can also be ore that has been refined to some extent to become concentrate. Once the ore is processed according to the method of the present invention to provide a concentrate solution, it can be easily supplied to downstream processes, such as electrometallurgical extraction processes. Thus, the inefficiencies in energy consumption of traditional refining processes (such as flotation, electrostatic separation, or magnetic separation or dehydration) can be avoided.

[0027] Generally, the ore used for the present invention is any crude ore or concentrate containing a metal or a metalloid. Preferably, the ore is selected from one or more of the following: iron ores, including hematite, goethite, magnetite, titanomagnetite, and pisolitic iron ore; aluminum-containing ores, including bauxite, cryolite, and corundum; gold ores, including gold-polysulfide, gold-quartz, gold-telluride, gold-tetradymite, gold-antimony, gold-bismuth-sulfosalt, gold-pyrrhotite, and gold-fahlore; manganese-containing ores, such as romanechite, manganite hausmannite, and rhodochrosite; lead ores, including galena, cerrusite, and anglesite; zinc ores, including calamine and smithsonite; cobalt-containing ores; uranium-containing ores; copper-containing ores, including copperpyrite, chalcopyrite, bornite, covellite, chalcocite, malachite, cuprite, and copper glance; nickel-containing ores, such as laterite and magmatic sulfide deposits; silver-containing ores, such as argentite; tin-containing ores, such as cassiterite, tinstone, stannite, or cylindrite; and quartz. In a particularly preferred embodiment, the ore is an iron ore rich in iron oxides, especially magnetite (Fe 3 O 4 )), hematite (Fe 2 O 3 ), goethite (FeO(OH)), limonite (FeO(OH)·n(H 2 O)), or siderite (FeCO 3 ).

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

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

[0030] One or more metal alkalis at high temperature comprise a super-alkaline medium. When in contact with the metal alkali, the ore completely dissolves or partially dissolves and / or the metal-containing part is chemically converted into a soluble substance. Without wishing to be bound by theory, it is believed that, for example, sulfide ores are converted into oxides.

[0031] Other compounds can promote the dissolution or chemical conversion of the ore. In particular, the addition of silicates can promote the dissolution or chemical conversion of the ore, especially concentrates.

[0032] The alkali metal alkalis or alkaline earth metal alkalis suitable for the present invention are preferably hydroxides, although other alkalis such as metal oxides or metal ammonium substances can also be used.

[0033] Generally, the metal alkali is selected from alkali metal alkalis such as lithium, sodium, potassium, rubidium or cesium hydroxides; or alkaline earth metal alkalis such as calcium, barium or strontium metal hydroxides. In a particularly preferred embodiment, the metal alkali is selected from lithium hydroxide, sodium hydroxide, potassium hydroxide or calcium hydroxide. In a particularly preferred embodiment, the super-alkaline medium comprises 45 wt% to 100 wt% of sodium hydroxide and / or potassium hydroxide.

[0034] One or more metal alkalis can be in contact with the ore, and the combination of metal alkalis can be in the form of a eutectic mixture. A eutectic mixture of sodium, potassium and / or lithium hydroxides is particularly preferred. In some embodiments, for economic reasons, NaOH is preferred, but pure NaOH may not be as effective as the eutectic system formed by the combination of NaOH and KOH.

[0035] The super-alkaline medium containing an alkali metal alkali or an alkaline earth metal alkali is contacted with the ore at high temperature, preferably at a temperature above 160 °C or above 200 °C, preferably above 250 °C, more preferably above 300 °C. In a particularly preferred embodiment, the alkali metal alkali or alkaline earth metal alkali is contacted with the ore at a temperature of 160 °C to 400 °C, preferably 200 °C to 350 °C, more preferably 250 °C to 350 °C.

[0036] For example, with regard to eutectic mixtures, the melting points of most mixtures of NaOH and KOH are lower than the melting points of the constituent compounds. For a molar ratio of 1:1 of NaOH:KOH, the eutectic forms at 170 °C. If there is adsorbed water or water of crystallization, such as in the ratio of NaOH:KOH:H 2 O of 1:1:1, the formation temperature of the eutectic can be lower than 100 °C.

[0037] Once the super-alkaline medium is in contact with the ore and the ore is partially or completely dissolved, the combination can be cooled to form a solid, and then reheated for further processing.

[0038] Fused metal alkalis, especially hydroxides, usually contain impurities such as water. Preferably, the metal alkalis incorporated into the superalkaline medium of the present invention contain no more than one mole of water per mole of hydroxide. Water can also be removed from the superalkaline medium by heating the superalkaline medium briefly to a higher temperature (i.e., >450 °C). Inert gas protection over the superalkaline medium can be used to limit or prevent reabsorption of water.

[0039] The metal alkalis used in the present invention can contain minor chemical impurities. For example, sodium hydroxide can form or contain minor amounts of sodium carbonate (Na 2 CO 3 ).

[0040] In a second aspect of the embodiments described herein, a method for refining ore is provided, the method comprising the steps of:

[0041] (i) contacting the ore with one or more metal alkalis at a high temperature, said metal alkalis preferably being alkali metal alkalis or alkaline earth metal alkalis;

[0042] (ii) feeding the solution formed in step (i) to a beneficiation process.

[0043] In one aspect of the present invention, the beneficiation process can be, for example, an extraction process for removing silica and / or alumina or other impurities including titanium dioxide, phosphorus, and manganese.

[0044] In another aspect of the present invention, the beneficiation process can be, for example, an extractive metallurgy process (preferably electrometallurgy) to deposit metals from the solution.

[0045] When the ore is contacted with one or more metal alkalis, the ore can dissolve completely or partially or a portion of the ore can be chemically converted into a soluble substance. Although the solution thus finally formed can be fed to a downstream extractive metallurgy process (such as an electrochemical process for selective electrodeposition of target metals), it may be advantageous to include steps to promote the extraction of specific elements (such as nickel, cobalt, molybdenum, lithium, aluminum, and silicon). The solution can be subjected to further beneficiation treatment.

[0046] Thus, in a third aspect of the embodiments described herein, a method for refining ore is provided, the method comprising the steps of:

[0047] (i) contacting the ore with one or more metal alkalis, preferably alkali metal alkalis or alkaline earth metal alkalis, at a high temperature to form a concentrate solution;

[0048] (ii) extracting one or more components of the ore from the concentrate solution;

[0049] and optionally,

[0050] (iii) Feed the extracted solution to an extractive metallurgy process (preferably electrometallurgy) to deposit the metal;

[0051] And optionally,

[0052] (iv) Send the extracted concentrate solution to a further ore beneficiation process.

[0053] In a fourth aspect of the embodiments described herein, a method for refining an ore is provided, the method comprising the steps of:

[0054] (i) Contact the ore with one or more metal alkalis, preferably alkali metal alkalis or alkaline earth metal alkalis, at a high temperature,

[0055] (ii) Convert the sulfides in the ore to oxides in solution;

[0056] (iii) Extract one or more oxides from the solution; and optionally,

[0057] (iv) Send the extracted oxides to a further refining process.

[0058] In a fifth aspect of the embodiments described herein, a method for refining an ore is provided, the method comprising the steps of:

[0059] (i) Contact the ore with one or more metal alkalis, preferably alkali metal alkalis or alkaline earth metal alkalis, at a high temperature;

[0060] (ii) Form a solution containing the dissolved components in the ore;

[0061] (iii) Remove components from the solution; and optionally,

[0062] (iv) Transport the purified solution in step (iii) to a downstream ore beneficiation process.

[0063] The components removed from the solution may include aluminum and silicate materials. The components removed from the solution may be converted into valuable commercial products, such as geopolymers (inorganic aluminum silicate polymers) or zeolites (commonly denoted as M n+ 1 / 2 (AlO 2 ) - (SiO 2 ) x ·yH 2 O, where M n+ 1 / 2 is a metal ion, usually Na + , K + , Ca 2+ , Mg 2+ or H + ).

[0064] In another aspect, the present invention provides a concentrate or refined ore produced by the method according to the present invention.

[0065] In another aspect, the present invention provides a commercial product produced by the method according to the present invention. In a particularly preferred embodiment, the commercial product is a metal.

[0066] Other aspects and preferred forms are disclosed in the specification and / or defined in the appended claims and form part of the description of the present invention.

[0067] In essence, the embodiments of the present invention stem from the recognition that superalkaline media can be used to convert ores (including crude ores) into useful concentrates or commercially valuable chemical products.

[0068] Advantages provided by the method of the present invention include:

[0069] It can be carried out at ambient pressure;

[0070] Low energy consumption;

[0071] Efficient conversion of ores into valuable chemicals;

[0072] Efficient refining of ores (especially crude ores);

[0073] Providing ore raw materials for further downstream ore refining; and

[0074] Providing chemicals suitable for processing into valuable chemical products.

[0075] From the detailed description given below, the further scope of application of the embodiments of the present invention becomes apparent. However, it should be understood that the detailed description and specific examples are given only by way of illustration when describing the preferred embodiments of the present invention, since various changes and modifications within the spirit and scope disclosed herein will be apparent to those skilled in the art from this detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Those skilled in the relevant art can better understand the preferred embodiments of the present application and the further disclosure content, objectives, advantages and aspects of other embodiments by referring to the following description of the embodiments in conjunction with the drawings. The drawings are only for illustration and thus do not constitute a limitation to the disclosure content of the present application, wherein:

[0077] Figure 1 Shows the use of molten hydroxides as superalkaline media at different temperatures.

[0078] Figure 2 Shows from hematite and NaOH / KOH eutectic at 250 °C, 275 °C, 300 °C, 325 °C

[0079] Iron is deposited in a solution formed by contacting at five temperatures including 350 °C. This figure records the relationship between current (I, unit: mA) and voltage (E, unit: volt).

[0080] Figure 3 This is a figure showing the effect of removing water from a super-alkaline medium. This figure records the relationship between current (I, unit: mA) and voltage (E, unit: volt). Detailed Description of the Invention

[0081] The present invention provides a method for refining ores (such as crude ores or concentrates) for downstream processes (especially extractive metallurgy). The method includes the step of contacting the ore with one or more metal alkalis, preferably a super-alkaline medium formed by alkali metal alkalis and / or alkaline earth metal alkalis, at a high temperature. When using two or more alkali metal alkalis and / or alkaline earth metal alkalis, the super-alkaline medium is usually in the form of a eutectic.

[0082] Figure 1 It shows the use of molten hydroxides as the super-alkaline medium at different temperatures. At a low temperature of about 100 °C, the super-alkaline medium is particularly suitable for dissolving substances such as silica and alumina from the ore. The concentrate can be used for other ore beneficiation processes, and alumina or silica can be used as valuable products. At a medium temperature of about 200 °C, the super-alkaline medium is particularly suitable for dissolving certain metal oxides that can be recovered by an electrolytic extraction process on the solution. At a higher temperature of about 300 °C, the super-alkaline medium is particularly suitable for dissolving metal (such as iron) oxides that can be recovered by an electrolytic extraction process on the concentrate.

[0083] In particular, the super-alkaline medium can be used for:

[0084] Completely or partially dissolving a metal-containing ore or chemically converting a metal-containing ore into a soluble substance, and then electrochemically depositing the metal from the solution;

[0085] Completely or partially dissolving the ore or chemically converting the ore into a soluble substance to facilitate the extraction of specific elements (such as nickel, cobalt, molybdenum, aluminum, lithium, and silicon), and then selectively electro-depositing the elements from the molten hydroxide, or chemically treating the dissolved elements;

[0086] Completely or partially converting a sulfide ore or concentrate (such as iron or nickel) into an oxide, and then subjecting these oxides to conventional treatments (chemical and / or electrochemical treatments - but not necessarily in molten hydroxide);

[0087] Partially dissolving a mineral ore to remove certain components (such as alumina and silica), and then subjecting the purified ore to downstream processes, and the removed components can be converted into commercial products such as geopolymers or zeolites.

[0088] Concentrate

[0089] For any of the above processes, additional compounds can be used to facilitate the dissolution of the ore or the chemical transformation of the components into soluble substances. In particular, the addition of silicates can enhance the transformation of solid oxides into metal silicates, which form a solution with the hyperalkaline medium. For example, it may be advantageous to add silicates such as quartz, feldspar, mica, amphibole, pyroxene, olivine, or aluminum silicate, especially for concentrates.

[0090] When the concentrate is initially exposed to molten hydroxide, it can form solid metal oxides. For example, nickel hydroxide or nickel sulfide concentrate can initially form solid iron-nickel oxides. Such solid oxides can also contain small amounts of other elements (such as iron, manganese, magnesium, copper, and cobalt), but rarely contain silicates.

[0091] By controlling process parameters (such as temperature and silica concentration), selective dissolution of the metals contained in the solid oxides can be carried out. The unwanted oxides will remain undissolved in the solid oxides, thereby controlling the purity or type of the solution.

[0092] The metal can be directly electrodeposited from the solution or separated by conventional methods in downstream processes (e.g., conventional electrolytic extraction after neutralization).

[0093] For sulfide concentrates, this process is particularly advantageous as it eliminates the need for a conventional high-temperature "roasting" process.

[0094] Examples

[0095] The present invention will be further described with reference to the following non-limiting examples:

[0096] Example 1 - Hematite

[0097] The method of the present invention was applied to an iron ore "dust" sample from Western Australia, which contained approximately 24 wt% Si, approximately 21 wt% iron, and 1 wt% Ni.

[0098] A hyperalkaline medium was formed, which included a eutectic of NaOH / KOH with a molar ratio of 1:1 at 200 °C. No attempt was made to remove water from the eutectic, and the equilibrium water content at this temperature was known to be 8 wt% to 10 wt%, depending on the NaOH:KOH ratio. When the hyperalkaline medium contacted the iron ore dust, a solution containing aluminates, silicates, and some iron oxides (magnetite, hematite, goethite, limonite, and siderite) was formed. However, most of the iron oxides remained solid at 200 °C. The concentration of iron oxides in the solution increased with increasing temperature, thereby reducing the water content at atmospheric pressure and completely dissolving at 350 °C.

[0099] Hematite was recovered from the solution at 200 °C by simply decanting the liquid and then rinsing with water. Analysis showed that the hematite had a purity of 93 wt% (iron content 61%) and was considered "export grade".

[0100] Example 2 - Nickel

[0101] The solution formed in Example 1 was maintained at 200 °C and atmospheric pressure and fed into an electrolytic cell in an electrolytic extraction process. The solution contained nickel derived from approximately 1% nickel in the crude ore.

[0102] Current passed from an inert gold anode through the solution and nickel and iron were deposited on the cathode in a ratio of 7:1 (Ni:Fe) during electroplating.

[0103] Example 3 - Dissolution of Ore in Molten Hydroxide

[0104] A superbasic medium was formed which consisted of a NaOH / KOH eutectic with a molar ratio of 1:1 at 300 °C. Hematite was gradually added and a solution was formed. At lower hematite concentrations, the solution was light green and the color gradually darkened. At a concentration of 200 g hematite in one liter of superbasic medium at 300 °C, the solution was dark green / black.

[0105] Similar tests were carried out on ores of different qualities with an iron content of 48% to 62% and all showed the same dissolution behavior.

[0106] The resulting solution exhibited low viscosity (similar to water) above 250 °C, which is particularly suitable for electrochemical processing. The solution was cooled to 25 °C at which temperature it became solid. The solid material could be remelted and further metallurgical extraction carried out.

[0107] At higher hematite concentrations in the superbasic medium, a solution formed 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 at temperatures up to 300 °C.

[0108] Both hematite and goethite are iron oxides in which the iron is in the oxidation state (III), giving the ore its characteristic red to reddish-brown "rust". The appearance of a distinct green color indicates that at least some of the iron(III) has changed its oxidation state during solution formation. Without wishing to be bound by theory, the green color of the solution may be due to:

[0109] The formation of soluble iron(II) silicate; and / or

[0110] The formation of "green rust", which consists of a mixed-valence (oxy)hydroxide with iron in mixed oxidation states (+2 and +3). Low melting point iron silicates exist in both Fe(II) and Fe(III) forms and only the Fe(II) silicate is green; and / or

[0111] Form other iron compounds in the solution.

[0112] Some possible reaction schemes support the observed conversion to Fe(II), all of which indicate the production of oxygen, which is consistent with the bubbles observed when the super-alkaline medium contacts the ore, as follows:

[0113] 2Fe 2 O 3 + 4NaOH → 4(Na + , HFeO 2 - ) + O 2

[0114] Fe 2 O 3 + 2NaOH → H 2 O + O 2 + 2FeO + 2Na (Sodium reacts with water to form NaOH and H 2 ; FeO is soluble in the alkaline medium.)

[0115] 2Fe 2 O 3 → 4FeO + O 2

[0116] 2Fe 2 O 3 + 2H 2 O → 4FeOOH, and then 4FeOOH + 2H 2 O → 4Fe(OH) 2 + O 2

[0117] The production of oxygen can be used for new applications, such as mining or refining minerals in an anaerobic or anoxic atmosphere. This will contribute to the exploitation of ore resources on planets such as the Moon, asteroids, or Mars.

[0118] Example 4 - Effect of Temperature on Iron Deposition

[0119] In the electrolytic extraction process maintained at atmospheric pressure, the solution of Example 3 was fed separately into the electrolytic cell and deposition was carried out in the electrolytic cell at temperatures of 250 °C, 275 °C, 300 °C, 325 °C, and 350 °C, respectively.

[0120] During the electroplating process, the current passed through the solution from the inert gold anode and iron was deposited on the iron cathode. It was noted that some parasitic hydrogen evolution also occurred during the deposition process.

[0121] Figure 2A graph showing the iron deposition results in each solution. The graph shows successful deposition at 250 °C, and the deposition rate increases with increasing temperature. The current increases with increasing temperature because the solution viscosity decreases and the normal activity increases.

[0122] Example 5 - Influence of Water in a Superalkaline Medium

[0123] Many alkali metal hydroxides or alkaline earth metal hydroxides are hygroscopic. In particular, the hygroscopicity of hydroxides is very strong, and even "pure" commercially available hydroxides often contain up to 10 wt% of water at 200 °C.

[0124] In electrochemical processes such as electrodeposition, the presence of water may lead to parasitic hydrogen evolution due to the decomposition of water. This side reaction reduces the overall efficiency of the electrodeposition reaction. In metal deposition, removing water is important, especially for iron deposition, because the thermodynamic reduction potential of water and iron oxides is more favorable for hydrogen evolution compared to iron deposition.

[0125] By heating the superalkaline medium briefly to a higher temperature (i.e., > 450 °C), water can be effectively removed. During the deposition process, an inert gas protection should be maintained above the solution to limit or prevent reabsorption of water. Heating the solution to > 350 °C for a long time during the deposition process also removes sufficient water, thus greatly reducing hydrogen evolution.

[0126] Figure 3 A graph showing the effect of removing water from a superalkaline medium. This graph records the relationship between current (I, in mA) and voltage (E, in volts). The first plot was made at 12.00 pm, the second at 14.00 pm, the third at 16.00 pm, and the last plot at 16.30 pm. The slope of the graph at 16.00 pm increases at about -2.2 volts because water is expelled from the superalkaline medium. Generally speaking, the graph shows that heating at 350 °C for a long time successfully removes water, but the process is rather slow. The graph also reflects the "true" iron deposition rate.

[0127] Example 6 - Relationship between Dissolution / Transformation of Iron Ore and Impurities

[0128] Three dry hematite samples (dried at 200 °C for 2 hours) with the same Pilbara origin but different iron contents (55%, 60%, and 62% Fe respectively) were reacted with molten hydroxide in three Teflon-lined containers.

[0129] At 310 °C, 20 g of ore sample per portion was added to 48 g of NaOH:KOH with a molar ratio of 1:1 and stirred for 1 minute to form a dark green solution. The temperature was maintained at 310 °C for 4 hours, and then the sample was cooled to room temperature under a Teflon lid.

[0130] To determine the dissolution / transformation of the ore, the Teflon-lined container with the ore / hydroxide sample was immersed in 150 mL of 5.5 M HCl and reacted with stirring for 24 hours. Then the liquid was decanted, 50 mL of fresh 5.5 M HCl was added, and the reaction was carried out for 2 hours, and decantation was performed again. Then the unreacted ore was washed three times with distilled water and dried in air at 150 °C before weighing. The characteristics of each sample are listed in Table 1.

[0131] Table 1:

[0132]

[0133]

[0134] As can be seen from Table 1, the saturation of the ore dissolved in the molten hydroxide increases with the increase in the impurity content in the ore. This is not unexpected because it is well known that the main impurities, silica and alumina, are easily soluble under alkaline conditions. However, the increase in the dissolved ore is greater than the increase in the impurities, with the iron content decreasing from 62% to 60% to 55%. This indicates that the impurities contribute to the dissolution of iron oxides in the molten hydroxide.

[0135] Two control experiments were carried out using 60% iron ore samples. In one experiment, the reaction time at 310 °C was reduced from 4 hours to 1 hour. This did not result in a change in the measured saturation of the dissolved ore, which fully indicates that the reaction / transformation time is much lower than 1 hour under the conditions used.

[0136] In a separate experiment, 20 g of 60% iron ore was reacted with 200 mL of 5.5 M HCl for 26 hours. The undissolved ore was rinsed in water, then dried and weighed. Exposure to HCl only caused a very small weight reduction (see Table 1), which means that the effect of exposure to the molten hydroxide is caused by the hydroxide rather than by the HCl titration.

[0137] Example 7 - Dissolution of Manganese(IV) Oxide (MnO 2 )

[0138] Manganese oxides are common impurities in Australian iron ores, usually limited to a maximum of about 1%. Manganese impurities rarely enter the iron oxide lattice but exist as well-defined MnO 2present in the form of particles. The content of manganese oxide in the ore is very low, so it is difficult to determine what changes occur to manganese oxide during the dissolution of (iron) ore. To solve this problem, 5 wt% of synthetic MnO was added to NaOH:KOH with a molar ratio of 1:1 at 300 °C. 2 The molten hydroxide immediately turned black and gradually changed to dark green / black after 24 hours without precipitation. Based on the color observed at this temperature, it is unlikely that manganese(II) hydroxide was formed because it is white and decomposes at about 140 °C. Instead, the green color indicates the partial formation of manganate(VI) ions.

[0139] Under the conditions known for producing iron from dissolved iron ore, an attempt was made to electro-deposit from the molten hydroxide solution at 300 °C. Nickel foil was used as the anode and cathode material, and a voltage of 1.8 V was applied between the electrodes. A bright green solution formed around the anode, indicating the formation of manganate as the oxidation product. Analyzing the deposit on the cathode, it was found to be a mixture of manganese oxides, in which manganese mainly exists in the +2 and +4 oxidation states.

[0140] This experiment shows that under the conditions used for electro-depositing dissolved iron substances, it is unlikely that metallic manganese (pure or as an alloying element) will deposit as a cathode product. Instead, trace impurities of manganese oxides can be expected.

[0141] Example 8 - Dissolution of Molten Hydroxide and Subsequent Separation at High Temperature

[0142] Sodium hydroxide (250 g) was melted in a heated laboratory-scale concentrator at 335 °C, and 25 g of dry (400 °C) iron ore powder was added. After one hour, the ore dissolved, the temperature rose to 370 °C, and it was maintained at this temperature for one hour. The elevated temperature caused the hydrolysis of the dissolved iron substances, resulting in the separation of a large amount of molten hydroxide in the conical part of the thickener. This allowed the iron-rich intermediate to be removed from the concentrator by gravity methods.

[0143] The main impurities in the ore (silica and alumina) were retained in the molten hydroxide solution in the form of silicates and aluminates. The process can be repeated by lowering the temperature to 335 °C, adding more iron ore, and raising the temperature to 370 °C again, resulting in the separation of more iron-rich intermediates.

[0144] The iron-rich intermediate was added to the eutectic melt of sodium hydroxide and potassium hydroxide, and electro-deposition was carried out at a temperature of 220 °C to 310 °C.

[0145] Dissolution and separation can also be carried out directly in the eutectic melt at high temperature. However, this results in additional costs because more expensive potassium hydroxide is consumed in the process of converting to potassium silicate and potassium aluminate.

[0146] Example 9 - Dissolving Iron Ore in a Molten Hydroxide Eutectic and then Removing Impurities from the Surface

[0147] 4 kg of a hydroxide eutectic (NaOH:KOH in a 1:1 weight ratio) was heated to 300 °C in a vertical kiln with a nickel lining. A 400 g sample of dry iron ore (hematite, 55% Fe) was added and stirred for 30 minutes until all of the iron ore was dissolved. Stirring was then turned off and the temperature was gradually and slowly decreased.

[0148] At a temperature close to the freezing point of the mixture (about 230 °C to 210 °C), liquid-liquid weight phase separation occurred. The bottom phase contained the heavier iron-rich material and the upper layer contained the impurity-rich material (mainly silicates and aluminates). The impurity-rich phase could be removed by carefully siphoning this phase from the upper layer of the solution.

[0149] When the temperature was further decreased (to 200 °C), a white crust formed on the surface of the solution, which was removed by simple mechanical means. Elemental analysis showed that this crust contained up to 50% of the impurities in the hydroxide matrix.

[0150] These methods for separating impurities in liquid or solid form from the dissolved ore provide a practical method prior to ore dressing to further process the iron-rich solution (e.g., by electrolytic extraction).

[0151] Example 10 - Magnetite Concentrate

[0152] At 310 °C, a 10 wt% sample of magnetite concentrate (67% iron, 5% silica, particle size of about 50 μm) was added to a mixture of molten NaOH and KOH in a 3:1 molar concentration. The magnetite concentrate dissolved rapidly with stirring to form a dark brown solution. This solution was used for electrolytic extraction of iron at 310 °C without further treatment.

[0153] The experiment was repeated with a NaOH:KOH ratio of 1:1 (molar) and the magnetite concentrate was dissolved at 310 °C. After dissolution was complete, the temperature was decreased to 240 °C before electrolytic extraction of iron was carried out.

[0154] Example 11 - Silica, Silicates, and Quartz

[0155] It is known that silica and other variants of the SiO 2 structure dissolve readily in alkaline media, which is an important aspect of various established industrial scale processing routes (e.g., for bauxite and spodumene minerals). However, these methods are based on the use of hydroxide solutions rather than molten hydroxides.

[0156] When 10 wt% of silica or sodium silicate powder is added to a molten hydroxide eutectic (1:1 NaOH:KOH) at 310 °C, the silica or sodium silicate immediately begins to react with the hydroxide, releasing water as part of the reaction. The release and evaporation of water cools the top of the molten hydroxide below its melting temperature. This results in the formation of a solidified sponge on top of the molten hydroxide, which due to its poor thermal conductivity, prevents further reaction of the silica. To solve this problem, the silica was slowly added to the molten hydroxide over 48 hours, resulting in a clear and transparent solution.

[0157] The reaction of quartz with the molten hydroxide has the same overall chemistry as silica, but is significantly slower and thus does not cause the same problem of forming a spongy crust / matrix. In fact, this makes the leaching of quartz easily integrable into the dissolution - electroextraction circuit (of silica).

[0158] Example 12 - Nickel Sulfide Ores and Concentrates

[0159] A sample of nickel sulfide ore from Western Australia with a particle size less than 3 mm (2.0% Ni, 14.1% Fe, 0.2% Cu, 6.3% S, and 9.9% MgO) was added to a NaOH:KOH eutectic melt at 250 °C (weight ratio 1:1) (6 wt% ore, 94 wt% hydroxide). The ore immediately began to dissolve and was completely dissolved after 3 minutes, turning the clear molten hydroxide into an orange / brown solution.

[0160] The dissolved ore solution was used as an electrolyte in an electroextraction experiment, where magnetic deposition was achieved at a voltage as low as 1.4 V. The magnetic deposit was washed in water and then immersed in 5.5 M HCl, where hydrogen evolution was detected, confirming the metallic nature.

[0161] Example 13 - Nickel Sulfide Ores and Concentrates

[0162] A sample of nickel sulfide concentrate from nickel sulfide ore from Western Australia with a particle size less than 1 mm (13.6% Ni, 38.7% Fe, 1.1% Cu, 32.8% S, and 3.5% MgO) was added to a NaOH:KOH eutectic melt at 250 °C (weight ratio 1:1) (3 wt% concentrate, 97 wt% hydroxide). The concentrate rapidly dissolved in the molten hydroxide within 2 minutes, forming a dark red - brown solution. No gas or vapor escaped during dissolution. The solution was left at 250 °C under a Teflon lid for 24 hours. After this, no precipitation was observed and the color remained the same but increased in intensity.

[0163] The dissolved concentrate solution was then used for electroextraction experiments. It was observed that the electrochemical current had started at a cell voltage of 0.6 V and reached a low current plateau at 0.9 V, then increased rapidly again at 1.2 V. A thin coating with a recognizable copper color was formed by cathodic deposition at 1.0 V, indicating that copper could be selectively deposited from the solution, but the current density was limited by the diffusion of low-concentration copper species in the solution.

[0164] The cathodic deposits obtained from the same solution at cell voltages of 1.6 V and 1.8 V were magnetic and produced hydrogen when exposed to dilute HCl solution. Notably, at a cell voltage of 1.8 V, a current density above 200 mA / cm 2 was measured, indicating that the dissolved metal species had very high diffusivity in the molten hydroxide solution.

[0165] Copper, nickel, and iron in sulfide ores and concentrates are contained in the sulfide structure, and their electrodeposition from the molten hydroxide solution confirmed that the sulfide bonding structure had been broken during the dissolution process. Therefore, it is expected that other sulfide ores (such as copper-iron sulfide ores like chalcopyrite) and their concentrates will undergo a similar dissolution process in molten hydroxides.

[0166] Notably, iron exists only in the +2 oxidation state in sulfide ores, while in most commercial oxides, all (hematite and goethite) or most (magnetite) iron exists in the +3 oxidation state. From the perspective of (electro)reduction, this means that much less current / energy is required to reduce iron from the sulfide structure than from oxides.

[0167] Although the present invention has been described in connection with its specific embodiments, it should be understood that further modifications can be made. This application is intended to cover any variations, uses, or modifications of the present invention that generally follow the principles of the present invention, and includes variations based on the common general knowledge or conventional means within the field of the present invention made in light of the present disclosure, provided that these variations can be applied to the essential features set forth above.

[0168] Without departing from the basic principles of the present invention, the present invention can be embodied in various forms. Therefore, it should be understood that, unless otherwise specified, the above embodiments do not limit the present invention, but should be broadly interpreted within the scope of the principles of the present invention defined by the appended claims. The described embodiments are considered illustrative in all respects and not restrictive.

[0169] All modifications and equivalent arrangements are intended to be included within the principles and scope of the present invention and the appended claims. Accordingly, the specific embodiments should be understood as illustrating many ways in which the principles of the present invention may be practiced. In the following claims, the means-plus-function clauses are intended to cover structures that perform the recited function, including not only structural equivalents but also functionally equivalent structures.

[0170] When a Markush group or other grouping is used herein, all individual members of the group and all possible combinations and subcombinations of the members of the group are intended to be individually included in the disclosure. Unless otherwise indicated, each combination of components described or exemplified herein can be used to practice the present invention.

[0171] Whenever a range is given in the specification (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 included in the given range, are intended to be included in the disclosure. It should be understood that any individual value included in a subrange or range or subrange included in the specification may be excluded from the claims.

[0172] As used herein, "comprising" is synonymous with "including", "containing", or "characterized by" and is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. "Consisting of" as used herein excludes any element, step, or ingredient not specified in the claim element. "Consisting essentially of" as used herein does not exclude materials or steps that do not materially affect the basic and novel characteristics of the claim. The broad term "including" is intended to cover the narrower "consisting essentially of" as well as the narrower "consisting of". Thus, in any recitation herein of the phrase "comprising one or more claim elements" (e.g., "comprising A"), the phrase is intended to cover the narrower, e.g., "consisting essentially of A" and "consisting of A". Thus, the broad term "including" is intended to provide specific support for "consisting essentially of" or "consisting of" in each instance of its use herein. The present invention, as described herein by way of example, may be practiced in the absence of any element or elements, limitation or limitations not specifically disclosed herein.

[0173] Those of ordinary skill in the art will appreciate that the present invention may be practiced using materials and methods other than those specifically exemplified without undue experimentation. All known functional equivalents of any such materials and methods are included in the present invention. The terms and expressions employed are used as descriptive terms and not of limitation, and in using such terms and expressions, it is not intended to exclude any equivalents of the features shown and described or portions thereof, but it should be recognized that various modifications are possible within the scope of the invention as claimed. Accordingly, it should be understood that although the present invention has been specifically disclosed by way of examples, preferred embodiments and alternative features, those skilled in the art may make modifications and variations to the concepts disclosed herein, and such modifications and variations are considered to be within the scope of the invention as defined by the appended claims.

[0174] Each reference cited herein is incorporated herein by reference in its entirety. These references may provide sources of materials, alternative materials, details of methods, and other uses of the present invention.

Claims

1. A method for providing a concentrate solution suitable for ore dressing processes, the method comprising the following steps: (i) contacting the ore with one or more metal alkalis at a high temperature.

2. The method according to claim 1, wherein the one or more metal alkalis are alkali metal alkalis or alkaline earth metal alkalis, the alkali metal alkalis are preferably selected from lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide or cesium hydroxide, the alkaline earth metal alkalis are preferably selected from calcium hydroxide, barium hydroxide or strontium hydroxide.

3. The method according to claim 1, wherein the one or more metal alkalis form a superalkaline medium that partially dissolves or completely dissolves the ore at a high temperature.

4. The method according to claim 1, wherein the one or more metal alkalis form a superalkaline medium containing 45 wt% to 100 wt% of sodium hydroxide and / or potassium hydroxide at a high temperature.

5. The method according to claim 1, wherein the high temperature is 160°C to 400°C, preferably 200°C to 350°C, more preferably 250°C to 350°C.

6. The method according to claim 1, wherein the ore is selected from one or more of the following: iron ore, preferably hematite, magnetite or goethite; aluminum-containing ore; gold ore; manganese-containing ore; lead ore; cobalt-containing ore; uranium-containing ore; copper-containing ore; nickel-containing ore, preferably nickel sulfide ore; silver-containing ore; tin-containing ore; silicon ore and quartz.

7. The method according to claim 1, further comprising the step of adding a silicate to the combination of the ore and one or more metal alkalis at a high temperature, the silicate is preferably quartz, feldspar, mica, amphibole, pyroxene, olivine or aluminum silicate.

8. The method according to claim 1, wherein the one or more metal alkalis form a superalkaline medium at a high temperature, and then the superalkaline medium is heated briefly at a high temperature to remove water.

9. The method according to claim 1, wherein the concentrate is fed to an ore dressing process, preferably a hydrometallurgical process.

10. The method according to claim 1, wherein the following further steps are performed on the concentrate: (ii) extracting one or more components of the ore from the concentrate solution; and optionally, (iii) feeding the extracted concentrate solution to a hydrometallurgical process, preferably electrometallurgy, to deposit metals; and optionally, (iv) feeding the extracted concentrate solution to a further ore dressing process.

11. The method according to claim 1, wherein the following further steps are performed on the concentrate: (ii) forming a solution containing the dissolved components in the concentrate; (iii) removing components from the concentrate solution; and optionally, (iv) transporting the purified solution in step (iii) to a downstream ore dressing process.

12. A concentrate produced by the method according to any one of claims 1 to 8.

13. A metal recovered by the ore dressing steps according to any one of claims 9 to 11.

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