Patent Application
20240410032
The mining of critical metals is an industry that supports various sectors including technology, aerospace, and renewable energy. These metals, such as iron, lithium, cobalt, nickel, and rare earth elements, are essential for manufacturing batteries, electronics, and other high-tech applications. Traditional mining methods often involve extensive drilling and excavation, which can lead to significant environmental degradation including deforestation, soil erosion, water contamination, and biodiversity loss. Moreover, the increasing demand for these metals, driven by the global shift towards sustainable technologies such as electric vehicles and renewable energy systems, is putting additional pressure on supply chains and raising concerns about the sustainability and ethical implications of extraction practices. Consequently, there is a growing need for innovative mining technologies that can efficiently and sustainably extract critical metals while minimizing environmental impact and adhering to stringent regulatory standards.
In some aspects, the techniques described herein relate to a mineral recovery solution including: a liquid or supercritical carbon dioxide component; a water component; and a chelator component.
In some aspects, the techniques described herein relate to a method of recovering a mineral, the method including: delivering a mineral recovery solution to a subterranean location, the mineral recovery solution including: a liquid or supercritical carbon dioxide component; a water component; and a chelator component; chelating a mineral with the chelator component to form a chelated mineral; mineralizing the liquid or supercritical carbon dioxide component; and recovering the chelated mineral.
In some aspects, the techniques described herein relate to a method of forming a mineral recovery solution, the method including: contacting a liquid or supercritical carbon dioxide component and a chelator component.
Reference will now be made in detail to certain embodiments of the disclosed subject matter, examples of which are illustrated in part in the accompanying drawings. While the disclosed subject matter will be described in conjunction with the enumerated claims, it will be understood that the subject matter expressed in the various embodiments herein is presented by way of illustrative example but is not presented in a limiting sense.
The present subject matter can include an integrated technology and comprehensive suite of methods for in situ liquid or supercritical CO2 enhanced mineral recovery and permanent carbon storage via carbonate mineralization of mafic-ultramafic formations. The present inventors have recognized, among other things, that challenges can exist in providing cost-effective transformative technologies to help decarbonize the mining industry, address depletion of high value ore grades, help minimize hazardous legacy of tailing piles, and ultimately help develop a resilient supply chain of domestic energy-relevant minerals. The present subject matter can be used to address one or more such challenges.
An aspect of the present subject matter can include a process that can be used for mining of energy relevant minerals using a carbon-negative technology that can leverage horizontal drilling technologies to deliver the disclosed mineral recovery solution as a leaching solution to mixed-grade ultramafic formations. As will be described further herein, energy-relevant mineral rich fluids produced from the mineral recovery solution can be brought to the surface for processing and CO2 can be permanently sequestered at depth in the form of carbonate minerals.
There are numerous benefits that can be associated with the disclosed mineral recovery solution. For example, according to some examples, novel carbon-negative technology may expand the mineral supply chain by harnessing low value assets while creating a carbon-negative pathway that can reduce energy cost by, according to different estimates, at least 50% or at least 63% and mineralizes about 100 to about 150 kg CO2 per kg of metal extracted, according to an illustrative example.
The disclosed mineral recovery solution can be used in a leaching mining operation. Leaching mining, also known as in situ leaching or solution mining, is a technique that can be used to extract metals from underground deposits. This method generally involves the circulation of a mineral recovery solution to chelate target metals, and the resulting solution containing the chelated minerals can then pumped back to the surface for mineral recovery
The integration of horizontal drilling into the leaching mining process has can enhance efficiency and can reduce environmental impact of mineral extraction. Horizontal drilling techniques generally involve the creation of a vertical well that reaches a desired depth of an ore body. From this location, a drilling apparatus can extend horizontally through the ore deposit. This method allows for extensive contact between the injected mineral recovery solution and the ore, as the horizontal wells generally traverse a larger section of the ore body compared to traditional vertical wells
Once the horizontal wells are established, a mineral recovery solution can be injected and allowed to permeate through the ore body, chelating the minerals as it progresses. The enriched solution can be collected either through the same horizontal wells or through separate recovery wells strategically placed within the ore body. The collected solution is generally processed on the surface to extract the valuable minerals, typically through techniques such as precipitation, adsorption, or ion exchange, as illustrative examples.
The use of horizontal drilling in leaching mining can enhance the efficiency of the mining process and can offer several environmental benefits. For example, this method can reduce the surface disruption typically associated with traditional mining methods, thereby reducing or even minimizing an environmental footprint. Additionally, use of the approach described herein can potentially increase the recovery rates of minerals by accessing parts of the ore body that are unreachable with vertical drilling approaches in the absence of horizontal drilling.
A mineral recovery solution according to the present disclosure can include a liquid carbon dioxide or a supercritical carbon dioxide, one or more chelators, and water. Liquid carbon dioxide is formed when CO2 is compressed above its critical pressure of 7.38 MPa (megapascals) and cooled below its critical temperature of 31.1° C. In this state, it does not behave like a typical liquid; instead, it has properties that are intermediate between a gas and a liquid. One characteristic of liquid CO2 is its high density. Additionally, liquid CO2 is non-flammable and relatively inert, which makes it a safer choice for many industrial processes as compared to flammable or more reactive materials.
When the temperature and pressure of CO2 are increased above its critical point (31.1° C. and 7.38 MPa), it enters a supercritical state. In this state, supercritical CO2 exhibits unique properties that differ significantly from those of either gas or liquid. It expands to fill its container like a gas but has a density like that of a liquid. This combination of properties makes supercritical CO2 an excellent solvent for a variety of applications, particularly in situations where non-toxic, non-flammable, and environmentally benign materials are desired.
The carbon dioxide of the liquid or supercritical carbon dioxide can be obtained from an emitted greenhouse gas source. For example, the carbon dioxide can be provided from an industrial emission, automotive emission, the atmosphere, or any other source. If the carbon dioxide is recovered from a greenhouse gas emission source, the subsequent mineralization of that carbon dioxide removes that source of carbon dioxide from the atmosphere.
In the mineral recovery solution, the liquid or supercritical carbon dioxide component is in range of from about 2 mol % to about 95 mol % of the mineral recovery solution, about 50 mol % to about 95 mol %, less than, equal to, or greater than about 2 mol %, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, or about 95 mol %.
Chelators, also known as chelating agents, are chemical compounds that have the ability to form multiple bonds with a single metal ion. They can be considered suitable for various industrial processes because they can effectively bind metal ions, forming stable, water-soluble complexes. The mineral recovery solution can include one chelator or a mixture of at least two chelators.
Suitable chelators include those that are capable of chelating nickel, iron, cobalt, copper, or mixtures thereof. In general, the chelators should be able to chelate at least 70 mol %, at least 75 mol %, at least 80 mol %, at least 85 mol %, at least 90 mol %, at least 95 mol % or about 100 mol % of the available target metal. Non-limiting examples of suitable chelators include EDTA (ethylenediaminetetraacetic acid), or EDDS (Ethylenediamine-N,N′-disuccinic acid), CDTA (cyclohexane diamine tetra acetic acid), PDTA (Propylenediamine-N,N,N′,N′-tetraacetic acid), and PDTA (1,3-propanediaminetetraacetic acid) ortho-Phenylenediamine-N,N,N′,N′-tetraacetic acid, and derivatives thereof. Derivatives of these chelators can include chemically modified versions. Chemically modified versions can include those with additional one or more functional groups synthesized thereto and/or versions with one or more functional groups removed.
Different chelators can be chosen for their selectivity to a target metals. In some examples, a mixture of at least two chelators can be included if a particular chelator is better suited for chelating one or more metals and another chelator is better suited for chelating one or more different metals. This can allow for effective recovery of multiple target metals. In examples, where multiple chelators are used, they may be present in the mineral recovery solution in substantially equivalent amounts or in different amounts.
Target metals can include nickel, iron, cobalt, copper, or mixtures thereof. It is within the scope of this disclosure to include further target metals.
The chelator can be present in the mineral recovery solution in a range of from about 0.01 mol % to about 7 mol %, about 0.01 mol % to about 0.2 mol %, less than, equal to, or greater than about 0.01 mol %, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6.5, or about 7 mol %.
The balance of the mineral recovery solution can be water. The water can be added to the mineral recovery solution or the water can be included by way of the liquid or supercritical carbon dioxide. The present inventors have also recognized that the mineral extraction solution comprising the combinations described herein may use relatively small amounts of water. For example, overall water usage of the in situ mining procedure using the mineral extraction solutions according to various examples described herein is up to 95% less compared to conventional mining that doesn't use the mineral extraction solution. A PH of the mineral recovery solution is not acidic (e.g., is equal to or greater than 7). The pH is will be controlled via the water-rock ratio, CO2—H2O ratios, and additional of chelating ligand additives to promote a combination of enhanced rock dissolution, carbonate precipitation, and critical mineral recovery, depending on the stage and exact goals of the process.
In operation, the mineral recovery solution can be flowed into a mine. The mine can be a network of porous rocks and can include shafts formed by horizontal drilling as described above. The mine can be deep. For example, the mine can be greater than 40 meters deep, greater than 60 meters deep, greater than 80 meters deep, greater than 100 meters deep, greater than 300 meters deep, greater than 700 meters deep, or greater than 900 meters deep. The mineral recovery solution can be formed at the time it is deployed to the mine. For example, the components of the mineral recovery solution can be stored in separate containers each in fluid communication with a manifold that combines the constituents at a desired level to form the mineral recovery solution that is sent to the mine. Once a desired amount of mineral recovery solution is provided to the mine, the mineral recovery solution is left for a soak duration ranging from about 1 month to about 18 months, about 2 months to about 17 months, about 5 months to about 15 months, less than, equal to, or greater than about 1 month, 2 months, 3, months, 4, months, 5 months, 6 months, 7 months, 8 months, 9 months, 10 months, 11 months, 12 months, 13 months, 14 months, 15 months, 16 months, 17 months, or about 18 months. The total soak time can depend on reaction rates of the mineral recovery solution and the mineral, injection rate of the mineral recovery solution, and the like. During that time, chelation occurs between the chelator and target metals. Additionally, mineralization of the liquid carbon dioxide or supercritical carbon dioxide occurs.
Mineralizing liquid or supercritical carbon dioxide refers to the process of using CO2 in its liquid or supercritical state to facilitate the formation of mineral carbonates from certain metal oxides. This process is particularly significant in the context of carbon capture and storage (CCS) technologies, where CO2 is not just stored but converted into a stable, solid form that can be safely sequestered. The supercritical CO2 reacts with the metal oxides to form stable mineral carbonates, such as calcium carbonate (CaCO3) or magnesium carbonate (MgCO3). This reaction is facilitated by the unique solvent properties of supercritical CO2, which allow it to penetrate porous rock formations and react more effectively with the available metal oxides. The end product of this reaction is a solid mineral that encapsulates the CO2 in a stable, non-gaseous form. This effectively removes CO2 from the atmosphere and stores it in a way that is less likely to be released back into the atmosphere. In general about 80 mol % to about 100 mol %, about 85 mol % to about 95 mol %, less than, equal to, or greater than about 80 mol %. 81, 82, 83, 84, 85, 86, 878, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or about 100 mol % of the carbon dioxide in the mineral recovery solution is mineralized.
The chelated target metals will stay in solution and remain underground in the mine until it can be pumped out of the mine. Once recovered, the target metals are released from the chelators. One method for recovering metals from chelators involves adjusting the pH of the solution. Many chelating agents bind metals more tightly under specific pH conditions. By altering the pH, either by making the solution more acidic or more alkaline, the stability of the metal-chelator complex can be disrupted, causing the metal to dissociate from the chelator. This method is particularly useful because it can be finely tuned to target specific metals and chelators, allowing for selective recovery. The pH can also be adjusted depending on the type, concentrations, and mixtures of ligands used. The ligands and CO2—H2O ratio can also be tailored to exert control on redox state of the production fluid to better chelate minerals/metals that are redox sensitive. The redox control can also be used to inhibit potentially deleterious effects, including sulfide oxidation. Another example of redox control using ligands and multiphase CO2—H2O fluids involves the dissolution of iron from minerals of interest during CO2-enhanced iron mining, in which iron dissolving from minerals will be bound with a ligand to preclude its incorporation into a carbonate so the iron can be extracted in a fluid phase. The iron may also be induced to exist as Fe3+ and transported as colloidal iron (oxyhyr) oxides, keeping iron in a form not suitable for incorporation into carbonate minerals.
Another approach is the use of ion exchange techniques, where ions that compete with the metal ions for the chelator are introduced into the system. By flooding the chelator with these competing ions, the metal ions can be displaced from the complex. This method is effective but requires a careful selection of competing ions to ensure that the metal is efficiently displaced without unwanted side reactions.
Thermal treatment can also be employed to recover metals from chelators. Heating the metal-chelator complex can weaken the bonds holding the metal, leading to the release of the metal ions. This method must be carefully controlled to avoid degrading the metal or the chelator, and it is generally used when other methods are not viable or efficient.
Chemical displacement involves adding a chemical agent that reacts with the metal-chelator complex to form a new compound, from which the metal can be more easily extracted. This could involve reducing agents that change the oxidation state of the metal, making it less likely to remain bound to the chelator. This method is particularly useful when dealing with robust chelators that do not easily release their bound metals under altered pH or thermal conditions.
Chelating the target metal also improves the overall yield compared to other mining techniques that require crushing of a rock or ore to recover the target metal where there is an inherent loss of target metal.
Various embodiments of the present invention can be better understood by reference to the following Examples which are offered by way of illustration. The present invention is not limited to the Examples given herein.
Sulfide nickel deposits are the primary source of mined nickel, with ˜93% being low grade Ni ore (0.2-2%). Nickel is extracted through a combination of energy intensive processes.
Concentrations of Ni are set at 1% and energy costs are ˜115 MJ/kg. Using the standard mine a base case (the Eagle Mine in the state of Michigan, USA), Ni metal production (2021) was 18,353 metric tons (mt); recovery rate of 84.1%. Co-product Cu metal had a higher recovery rate (97.3%), yielding ˜18,419 mt. Setting Ni at $1.24/lb ($2.76/kg) for 2021, capital cost were ˜$16.3 M; total revenue>$462M.
A single 900 m deep well with 12 horizontal channels (100 m each) will be utilized to (1) deliver super critical carbon dioxide fluids (100 mg/L lixiviants; 50 L/sec) and (2) extract Ni-rich fluids. Crushing and grinding of the Ni ore will be eliminated, saving ˜21 MJ/kg Ni (based on the assumption that 20 kWh energy is needed to crush and grind a ton of ore grading 1% Ni). Additional processes (e.g., air flotation, high-temperature smelting, and high-temperature oxidation) are eliminated. The extracted fluid (15 vol % of injected super critical carbon dioxide) will undergo a standard separation method (e.g., ion exchange, crystallization, and electrorefining) to produce Ni (>95%).
Based on 11-years of operations, equivalent Ni and Cu production is assumed (research case) to compare capital and energy cost with the base case. Total energy for drilling, super critical carbon dioxide compression, pumping, and electrorefining is estimated at 42 MJ/kg (0.3% Ni in extracted fluid), equating to ˜63% energy savings. Capital cost for Ni production (research case), based on the accumulated productivity over 11 years (decay ratio of 0.9) is ˜$1.37/kg Ni (Table 1). This approach includes sequestering 83,000 mt of carbon dioxide as a carbonate mineral while producing more than 700 equivalent mt of Ni metal annually. The unit carbon dioxide emission reduction is estimated to be 110 kg CO+/kg Ni.
The terms and expressions that have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the embodiments of the present invention. Thus, it should be understood that although the present invention has been specifically disclosed by specific embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those of ordinary skill in the art, and that such modifications and variations are considered to be within the scope of embodiments of the present invention.
The following exemplary aspects are provided, the numbering of which is not to be construed as designating levels of importance:
Throughout this document, values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of “about 0.1% to about 5%” or “about 0.1% to 5%” should be interpreted to include not just about 0.1% to about 5%, but also the individual values (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. The statement “about X to Y” has the same meaning as “about X to about Y,” unless indicated otherwise. Likewise, the statement “about X, Y, or about Z” has the same meaning as “about X, about Y, or about Z,” unless indicated otherwise.
In this document, the terms “a,” “an,” or “the” are used to include one or more than one unless the context clearly dictates otherwise. The term “or” is used to refer to a nonexclusive “or” unless otherwise indicated. The statement “at least one of A and B” or “at least one of A or B” has the same meaning as “A, B, or A and B.” In addition, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. Any use of section headings is intended to aid reading of the document and is not to be interpreted as limiting; information that is relevant to a section heading may occur within or outside of that particular section. A comma can be used as a delimiter or digit group separator to the left or right of a decimal mark; for example, “0.000,1” is equivalent to “0.0001.” All publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference should be considered supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls.
In the methods described herein, the acts can be carried out in any order without departing from the principles of the invention, except when a temporal or operational sequence is explicitly recited. Furthermore, specified acts can be carried out concurrently unless explicit claim language recites that they be carried out separately. For example, a claimed act of doing X and a claimed act of doing Y can be conducted simultaneously within a single operation, and the resulting process will fall within the literal scope of the claimed process.
The term “about” as used herein can allow for a degree of variability in a value or range, for example, within 10%, within 5%, or within 1% of a stated value or of a stated limit of a range, and includes the exact stated value or range.
The term “substantially” as used herein refers to a majority of, or mostly, as in at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%. The term “substantially free of” as used herein can mean having none or having a trivial amount of, such that the amount of material present does not affect the material properties of the composition including the material, such that about 0 wt % to about 5 wt % of the composition is the material, or about 0 wt % to about 1 wt %, or about 5 wt % or less, or less than or equal to about 4.5 wt %, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.01, or about 0.001 wt % or less, or about 0 wt %.
This application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 63/472,457 entitled “SUPERCRITICAL CO2-BASED MINING FOR CARBON NEGATIVE CRITICAL MINERAL RECOVERY,” filed Jun. 12, 2023, the disclosure of which is incorporated herein in its entirety by reference.
This invention was made with Government support under Contract DE-AC0576RL01830 awarded by the U.S. Department of Energy. The Government has certain rights in the invention.
| Number | Date | Country | |
|---|---|---|---|
| 63472457 | Jun 2023 | US |
