WO2024196975A1 - Methods for chloride sequestration - Google Patents

Abstract

The present technology relates to the sequestration of chloride streams from industrial processes.

Description

METHODS FOR CHLORIDE SEQUESTRATION FIELD OF TECHNOLOGY [0001] The present technology generally relates to methods for chloride sequestration. BACKGROUND [0002] Many industrial processes generate chlorine or chlorides as by-products. Depending on the nature and quantity of impurities in these by-products, they may be commercially valuable, but in some cases, they are not, and it is desirable to dispose of them. Therefore, there is a need for processes that provide for safe, economical, and environmentally friendly modalities for the sequestration of chlorine and chloride containing streams. SUMMARY OF TECHNOLOGY [0003] The present technology provides for processes for the sequestration of chloride containing streams by injecting them into specific geological formations that promote the reduction of the chlorine or other chloride molecule by mineral substrates. In some cases, the mineral substrates comprise metal compounds where the metal components are initially in a less than maximal oxidation state. In other cases, the mineral substrates comprise sulfides or sulfites. In still other cases, the mineral substrates comprise bromide. In still other embodiments, the geologic formations comprise carbonates which serve as sinks for the hydrogen chloride or other chlorides generated by the chloride-metal redox reaction. In other aspects, the present technology provides for methods of reclamation of the sequestered chlorides as metal chloride brines. In still other aspects, the present technology provides for the production of bromine by the reaction of chlorine with bromide anion. [0004] The present technology provides for a method of chloride sequestration comprising: a) obtaining chloride; b) identifying a hypoxic geological formation, c) creating a new, or identifying an existing access point in the geological formation, d) injecting the chloride into the access point, and d) optional capping the access point. BRIEF DESCRIPTION OF THE FIGURES [0005] Figure 1 is a schematic representation that outlines the general process of chloride sequestration by injection into appropriate geological formations. 302853711.1 [0006] Figure 2 is a schematic representation that outlines the general process of chloride sequestration through reaction with hydrogen followed by the use of the generated hydrogen chloride to leach and reclaim metal chloride brines from appropriate geological formations. DETAILED DESCRIPTION OF THE TECHNOLOGY [0007] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of ordinary skill in the art to which the inventions belong. All patents, patent applications, published applications and publications, websites and other published materials referred to throughout the entire disclosure herein, unless noted otherwise, are incorporated by reference in their entirety. In the event that there are a plurality of definitions for terms herein, those in this section prevail. Where reference is made to a URL or other such identifier or address, it is understood that such identifiers can change and particular information on the internet can come and go, but equivalent information can be found by searching the internet. Reference thereto evidences the availability and public dissemination of such information. [0008] While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any variations, uses, or adaptations of the invention, including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as follows in the scope of the appended claims. [0009] As used herein, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. [0010] As used herein, ranges and amounts can be expressed as “about” a particular value or range. “About” also includes the exact amount. Hence “about 5 percent” means “about 5 percent” and also “5 percent.” [0011] As used herein, the term “about” means within typical experimental error for a measurement typically used for purpose intended, or, if referred to in the context of a process parameter, the term about should be construed in the context of the sensitivity of such process to the particular parameter. 302853711.1 [0012] When a list of parameters or ranges is preceded by the term “about”, it is intended that the term “about” applies to each of the members of the list. [0013] As used herein, “optional” or “optionally” means that the subsequently described event or circumstance does or does not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not. For example, an optional component in a system means that the component may be present or may not be present in the system. [0014] As used herein, “weight percent” or “wt %” refers to the concentration of a substance as the weight of that substance divided by the total weight of the composition and multiplied by 100. [0015] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub- combination. All combinations of the embodiments pertaining to the invention are specifically embraced by the present invention and are disclosed herein just as if each and every combination was individually and explicitly disclosed. In addition, all sub-combinations of the various embodiments and elements thereof are also specifically embraced by the present invention and are disclosed herein just as if each and every such sub-combination was individually and explicitly disclosed herein. [0016] As used herein, the term “chloride” means elemental chlorine in its monoatomic state or diatomic state, Cl-, HOCl, HClO2, HClO3, HClO4, ClO-, ClO2-, ClO3-, ClO4-, ClO2, their salts, coordination compounds, inclusion compounds and combinations thereof. When appearing in combination with another element or molecule, it is understood that the combination term refers to chemically meaningful compositions, i.e., the combination term “magnesium chloride” may refer to MgCl2, Mg(ClO3)2, or other chemically viable salt and not to a chemically nonsensical composition such as “magnesium chlorine.” [0017] As shown in Fig. 1, the present technology provides for devices, methods, and systems for the sequestration of chlorine, and especially chlorine which otherwise cannot be sold 302853711.1 commercially due to the location of generation or impurity profile, by injection into a hypoxic geological formation. [0018] As shown in Fig. 2, the chlorine sequestration is coupled with the concomitant generation of metal chloride brine, and a chlorine generating metal electrowinning process. In a non-limiting example, the chlorine generating process produces chlorine and magnesium metal. The chlorine is converted to hydrogen chloride with a hydrogen burner, or a chlorine-hydrogen fuel cell, and the resulting hydrochloric acid is injected into a magnesium oxide, hydroxide, or carbonate bearing geological formation, causing magnesium chloride to be generated. The magnesium chloride is removed from the geological formation as a brine, depending on natural ground water or injected water, and dehydrated to a desired state of hydration where it is suitable for use in the electrowinning process using the heat generated from the hydrogen burner or the electrical energy from the chlorine-hydrogen fuel cell. [0019] In one embodiment, the present technology provides for a method of chloride sequestration comprising: a) identifying a hypoxic geological formation, b) creating a new, or identifying an existing access point in the geological formation, c) injecting chloride into the access point, and d) optionally capping the access point. [0020] In one embodiment, the present technology provides for a method of chloride sequestration comprising: a) obtaining chloride, b) identifying a hypoxic geological formation, c) creating a new, or identifying an existing access point in the geological formation, d) injecting the chloride into the access point, and e) optionally capping the access point. [0021] In one embodiment, the present technology provides for a method of chloride sequestration comprising: a) obtaining chloride, b) identifying a hypoxic aquifer, c) creating a new, or identifying an existing access point in the aquifer, d) injecting the chloride into the access point, and e) optionally capping the access point. [0022] In one embodiment, the present technology also provides for a method of chloride sequestration coupled with the conversion of mineral deposits to metal chloride salt comprising: a) obtaining chloride, b) identifying a hypoxic geological formation bearing metal hydroxide, oxide, or carbonate deposits, c) creating a new, or identifying an existing access point in the geological formation, d) injecting the chloride into the access point, e) injecting water into the 302853711.1 access point, thus forming a solution of converted metal chloride salt, and f) removing the converted metal chloride salt solution from the access point. [0023] In one embodiment, the present technology also provides for a method of chloride sequestration coupled with the conversion of mineral deposits to a metal chloride salt solution comprising: a) obtaining chloride, b) identifying a hypoxic aquifer bearing metal hydroxides, oxides, or carbonates, c) creating a new, or identifying an existing access point in the aquifer, d) injecting the chloride into the access point, and e) removing the converted metal chloride salt solution from the access point. [0024] In one embodiment, the present technology also provides for a method of chloride sequestration comprising: a) reacting chloride with hydrogen to form hydrogen chloride and heat of combustion, and b) using the heat of combustion in a magnesium chloride salt or magnesium metal preparation process. [0025] In one embodiment, the present technology also provides for a method of chloride sequestration comprising: a) obtaining chloride, b) obtaining hydrogen, c) reacting the chloride with the hydrogen forming hydrogen chloride and heat of combustion, and d) using the heat of combustion in a magnesium chloride salt or magnesium metal preparation process. [0026] In one embodiment, the present technology also provides for a method of chloride sequestration coupled with the conversion of mineral deposits to a metal chloride salt solution comprising: a) reacting chloride with hydrogen to form hydrogen chloride and heat of combustion, b) identifying a geological formation bearing metal hydroxide, oxide, or carbonate deposit, c) creating a new, or identifying an existing access point in the geological formation, d) injecting the hydrogen chloride and water into the access point, and e) removing the converted metal chloride salt solution from the access point. [0027] In one embodiment, the present technology also provides for a method of chloride sequestration coupled with the conversion of mineral deposits to a metal chloride salt solution comprising: a) obtaining chloride, b) obtaining hydrogen, c) reacting the chloride with the hydrogen forming hydrogen chloride and heat of combustion, d) identifying a geological formation bearing metal hydroxide, oxide, or carbonate deposit, e) creating a new, or identifying an existing 302853711.1 access point in the geological formation, f) injecting the hydrogen chloride and water into the access point, and g) removing the converted metal chloride salt solution from the access point. [0028] In one embodiment, the present technology also provides for a method of chloride sequestration coupled with the conversion of mineral deposits to a metal chloride salt solution comprising: a) obtaining chloride, b) obtaining hydrogen, c) reacting the chloride with the hydrogen forming hydrogen chloride and heat of combustion, d) identifying an aquifer bearing metal hydroxide, oxide, or carbonate deposit, e) creating a new, or identifying an existing access point in the aquifer, f) injecting the hydrogen chloride into the access point, and g) removing the converted metal chloride salt solution from the access point. [0029] In one embodiment, the present technology also provides for a method of chloride sequestration coupled with the conversion of mineral deposits to a metal chloride salt solution comprising: a) obtaining chloride, b) obtaining hydrogen, c) reacting the chloride with the hydrogen forming hydrogen chloride and heat of combustion, d) identifying a geological formation bearing metal hydroxide, oxide, or carbonate deposit, e) creating a new, or identifying an existing access point in the geological formation, f) injecting the hydrogen chloride and water into the access point, g) removing the converted metal chloride salt solution from the access point, and h) using the heat of combustion in a magnesium chloride salt or magnesium metal preparation process. [0030] In one embodiment, the present technology also provides for a method of chloride sequestration coupled with the conversion of mineral deposits to a metal chloride salt solution comprising: a) obtaining chloride, b) obtaining hydrogen, c) reacting the chloride with the hydrogen forming hydrogen chloride and heat of combustion, d) identifying an aquifer bearing metal hydroxide, oxide, or carbonate deposit, e) creating a new, or identifying an existing access point in the aquifer, f) injecting the hydrogen chloride into the access point, g) removing the converted metal chloride salt solution from the access point, and h) using the heat of combustion in a magnesium chloride salt or magnesium metal preparation process. [0031] In one embodiment, the present technology also provides for a method of chloride sequestration coupled with the conversion of mineral deposits to a metal chloride salt solution comprising: a) obtaining chloride, b) obtaining hydrogen, c) reacting the chloride with the hydrogen forming hydrogen chloride and heat of combustion, d) identifying a geological formation 302853711.1 bearing iron hydroxide, oxide, or carbonate deposit, e) creating a new, or identifying an existing access point in the geological formation, f) injecting the hydrogen chloride and water into the access point, g) removing the converted iron chloride salt solution from the access point, h) using the iron chloride salt in a process to remove sulfate or borate from a brine. [0032] In one embodiment, the present technology also provides for a method of chloride sequestration coupled with the conversion of mineral deposits to a metal chloride salt solution comprising: a) obtaining chloride, b) obtaining hydrogen, c) reacting the chloride with the hydrogen forming hydrogen chloride and heat of combustion, d) identifying an aquifer bearing calcium hydroxide, oxide, or carbonate deposit, e) creating a new, or identifying an existing access point in the aquifer, f) injecting the hydrogen chloride into the access point, g) removing the converted calcium chloride salt solution from the access point, and h) using the calcium chloride salt in a process to remove sulfate or borate from a brine. [0033] In one embodiment, the present technology also provides for a method of chloride sequestration coupled with serpentinization and conversion of mineral deposits to a metal chloride salt solution comprising: a) obtaining chloride, b) identifying a geological formation bearing ferromagnesian minerals, c) creating a new, or identifying an existing access point in the geological formation, d) injecting the chloride and water into the access point, and e) removing the converted metal chloride salt solution from the access point. [0034] In one embodiment, the chloride may be obtained in the commercial market. Where a chloride producer has chloride that due to circumstances, like, but not limited to, impurity profile, market conditions, or transportation costs, cannot be economically sold in the chloride marketplace, the chloride producer may be motivated to pay a disposal fee for the chloride, thus the present technology provides for a revenue stream by providing an economically advantageous means of disposing unwanted chloride. [0035] In another embodiment, the chloride may be obtained from the electrowinning of metals from their metal chloride salt. Typically, through such processes include, but are not limited, to magnesium, titanium, calcium, sodium, rubidium, lithium or potassium. [0036] In still another embodiment chloride may be obtained from the operation of caustic soda production through chlor-alkali processes. 302853711.1 [0037] In one embodiment, the hypoxic geological formation is an aquifers. [0038] As used herein, the term “access point” means one or plurality of boreholes. [0039] Generally, a borehole is a narrow shaft bored in the ground, either vertically or horizontally. A borehole may be constructed for many different purposes, including the extraction of water (drilled water well and tube well), other liquids (such as petroleum), or gases (such as natural gas). It may also be part of a geotechnical investigation, environmental site assessment, mineral exploration, temperature measurement, as a pilot hole for installing piers or underground utilities, for geothermal installations, or for underground storage of unwanted substances, e.g. in chloride sequestration, or for temporary storage of substances for subsequent extraction and reuse. [0040] In some embodiments, the access point may be a single borehole or an array of multiple boreholes, some serving for the injection of chloride and water, one or more being used for the removal of metal chlorides salt formed during the process. [0041] In some embodiments, chloride may be injected alone, or in other cases, mixed with water and the mixture being injected through the same borehole. In some cases, the injection of chloride may be simultaneous with the injection of water, or the injection of one may precede the injection of the other. In some cases, the injection of hydrogen chloride may be simultaneous with the injection of water, or the injection of one may precede the injection of the other. [0042] In some embodiments, where the access point is an array of boreholes, the array may be spread out over an area of about 1 square meter to about 1 square kilometer. In some embodiments, where the access point is an array of boreholes, the array may be spread out over an area of about 1 square kilometer to about 10 square kilometers. In some embodiments, where the access point is an array of boreholes, the array may be spread out over an area of about 10 square kilometers to about 100 square kilometers. In some embodiments, where the access point is an array of boreholes, the array may be spread out over an area of about 100 square kilometers to about 10000 square kilometers. [0043] In some embodiments, a borehole may extend from about 1 meter to about 10 meters below the surface. In other embodiments, a borehole may extend from about 10 meters to about 100 meters below the surface. In still other embodiments, a borehole may extend from about 302853711.1 100 meters to about 1000 below the surface. In still other embodiments, a borehole may extend from about 1000 meters to about 10000 meters below the surface. [0044] In some embodiments, where the access point is an array of boreholes, the individual boreholes may be at approximately the same level, or at different levels. [0045] In another embodiment, the metal chloride salt solution may be removed from the geological formation or aquifer through the same borehole as the chloride or water, or a separate borehole. [0046] In some embodiments where the chloride is chlorine, HCl produced by the combustion of the chlorine and hydrogen is used to convert metal hydroxides, oxides, or carbonates into metal chloride salt in situ below ground. [0047] In some embodiments where the chloride is chlorine, HCl produced by the combustion of the chlorine and hydrogen is used to convert metal hydroxides, oxides, or carbonates into metal chloride salt above ground. [0048] In still other embodiments, Cl₂ produced by the downs process of alkali metal production may be injected into the access point. [0049] In still other embodiments, HCl produced by magnesium oxide production through the roasting of magnesium chloride containing brines, instead of HCl produced by the combustion of chloride and hydrogen, may be injected into the access point. [0050] In still other embodiments, HCl produced by metal chloride dehydration processes, instead of HCl produced by the combustion of chloride and hydrogen, may be injected into the access point. [0051] In some embodiments, the HCl may be obtained by the reverse deacon reaction. In some embodiments, the HCl may be obtained by a hydrogen-chlorine fuel cell. [0052] In still other embodiments, magnesium chloride bearing brine may be hydrolytically dehydrated to yield magnesium hydroxide, magnesium hydroxychloride, magnesium oxide or combinations thereof, and the concomitantly produced HCl may be injected into the access point. 302853711.1 [0053] In still other embodiments, magnesium chloride bearing brine may be hydrolytically dehydrated to yield magnesium hydroxide, magnesium hydroxychloride, magnesium oxide or combinations thereof, and the concomitantly produced HCl may be injected into the access point to generate new magnesium chloride bearing brine. The generated magnesium hydroxide, magnesium hydroxychloride, magnesium oxide or combinations thereof are used to capture carbon dioxide from the atmosphere, bodies of water of industrial waste streams to provide a carbon capture method and system. [0054] In some embodiments, the hypoxic geological formations include, but are not limited to sediment hosted copper deposits, porphyry deposits, epithermal precious metal deposits, layered mafic intrusions, placer deposits, nickel laterite deposits, sedimentary exhalative deposits, Mississippi Valley Type deposits, Volcanic massive sulfide deposits, orogenic deposits, skarn deposits, and minerals sands. [0055] In general, geological formations favorable for the operation of the chloride sequestration methods described herein are those which bear a relatively large percentage of minerals having metal components in their less than maximal oxidation state. For example, mineral deposits bearing large amounts of Fe²⁺ are favorable for chloride sequestration, as the reduction of chloride can be coupled with the oxidation of Fe²⁺ to Fe³⁺. Likewise, other non- limiting examples include mineral deposits bearing Mn, Zn, Al, Ti, Cu and Zr. [0056] Geological formations that comprise aquifers bearing such minerals having their metal components in less than maximal oxidation states are also favorable for the chloride sequestration methods described herein. [0057] In some embodiments, the aquifers are a source of brines such as Salton Sea brines, Upper Rhine Valley brines, calcium chloride brines of Central Michigan, Permian O&G brines, West Texas O&G brines, Smackover Formation brines in Arkansas, Turkish geothermal brines, Alberta O&G brines, North Sea O&G brines, and Kenyan geothermal brines. [0058] In some embodiments, the use of aquifers is advantageous, as the acidic products of the chloride sequestration methods described herein may be used, either above ground, or, in situ, to convert metal oxides, hydroxides, and carbonates into metal chloride salt which may be recovered and either used or sold commercially. 302853711.1 [0059] In some embodiments, in the case where the geological formation is an aquifer, water may not need to be injected into the access point in order to solubilize the metal chloride salt. But, depending on the natural pressure of the aquifer, water or a gas may need to be injected in order to facilitate the removal of the metal chloride salt solution formed by the action of the chloride or hydrogen chloride on the formation. [0060] In some embodiments, the aquifer may be a pressurized aquifer. [0061] In some embodiments of the invention, the pressurized aquifer can push water/brine to the surface where it is mixed with chloride, and then reinjected back underground in a nearby location. The reinjection location may be the same borehole as used to source the water/brine, or it may be located less than about 1 m, 2 m, 3 m, 4 m, 5 m, 10 m, 15 m, 20 m, 25 m, 50 m, 100 m, 250 m, 500 m, 1000 m, 2500 m, 5000m or 10000 m from the borehole as used to source the water/brine. [0062] In some embodiments, the chloride is injected into the access point as a gas at less than about 10 bar, 20 bar, 30 bar, 40 bar, 50 bar, 100 bar, or 250 bar. [0063] In still other embodiments, a pressurized aquifer may be a spent oil well that produces a liquid discharge that is at least 95% water. [0064] In some other embodiments, the hydrogen may be obtained in situ, through naturally occurring or induced serpentinization. [0065] In still some other embodiments, the hydrogen may be obtained by coupling a reverse deacon reaction (reaction t) with the electrolysis of the resultant hydrogen chloride. [0066] Serpentinization is a form of low-temperature (0°C to ~600 °C) metamorphism of ferromagnesian minerals in mafic and ultramafic rocks, such as dunite, harzburgite, or lherzolite. These are rocks low in silica and composed mostly of olivine ((Mg₂ ⁺, Fe₂ ⁺)2SiO₄ ^4-), pyroxene (XY(Si,Al)₂O₆), and chromite (approximately FeCr₂O₄). Serpentinization is driven largely by hydration and oxidation of olivine and pyroxene to serpentine group minerals (antigorite, lizardite, and chrysotile), brucite (Mg(OH)2), talc (Mg3Si4O10(OH)2, and magnetite (Fe3O4). Under the unusual chemical conditions accompanying serpentinization, water is the oxidizing agent, and is itself reduced to hydrogen. This leads to further reactions that produce rare iron group native 302853711.1 element minerals, such as awaruite (Ni₃Fe) and native iron; methane and other hydrocarbon compounds; and hydrogen sulfide. [0067] In some embodiments, the products of serpentinization having reductive capacity for the chloride sequestration methods described herein may be formed by natural processes. [0068] In other embodiments, serpentinization may be induced in the identified geological formations by the injection of water or water containing such additives such as hydraulic fracturing sand. [0069] In some embodiments, hydrogen may be obtained from the operation of caustic soda production through chlor-alkali processes. [0070] In still other embodiments, hydrogen chloride may be obtained by recombining the chlorine and hydrogen outputs of chlor-alkali processes. [0071] In some embodiments, where hydrogen chloride is injected into a geological formation, the geological formation in this case does not need to be hypoxic, but bearing significant amounts and concentration of metal oxides, hydroxides, or carbonates. The preferred amounts of metal oxides, hydroxides or carbonates being more than about 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.6%, 99.7%, 99.8%, or 99.9%. [0072] The general reactions that are induced by the chloride sequestration methods described herein can be classified as chloride sequestration reactions and carbonate mineral decomposition reactions. The equations are presented here in their simplest formal form and the reactants may, as appropriate in the context the reactions are happening in, be in the form of liquids, solids, gases, solutions, or as supercritical fluids. [0073] In some embodiments, the chloride may be injected into the geological formation as a gas, or, depending on the required injection temperature and pressure, as a liquid or supercritical fluid. [0074] In some embodiments, the products of the subsurface reactions like CaCl2 or FeCl3 are produced from the underground aquifer and used in evaporation pond circuits for chemical 302853711.1 modification of brine chemistry, such as the removal of SO₄ ^2-, BO₃ ^3-, or other impurities from brines in the production of MgCl2 concentrates. [0075] In still some other embodiments, the injection of the chloride and optionally water into the access point results in an increase in the permeability of the geological formation, thus facilitating the sequestration process. In some instances, hydraulic fracturing sand may be added to the water during injection. [0076] In still some other embodiments, the injection of the chloride and optionally water into the access point results in an increase in the permeability of the geological formation, thus facilitating the removal of the metal chloride salt produced by the sequestration process. [0077] In some embodiments, metal oxides and hydroxides may be converted to metal chlorides through the reactions of the products of the chloride sequestration reactions with minerals such as, but not limited to, calcium hydroxide, calcium oxide, magnesium hydroxide, magnesium silicate or barium hydroxide. [0078] In still other embodiments, sulfur dioxide or trioxide from the heat induced conversion of magnesium sulfate to magnesium oxide, as shown: 2MgSO4−→2MgO+2SO2↑+O2↑ or 2MgSO4−→2MgO+2SO3, may be scrubbed by contacting it with aqueous hypochlorite obtained from a chloride generating process described herein. This process may be conducted above ground, in an appropriate reactor, or the sulfur oxides may be injected along with chloride into the access point for reaction and sequestration of the products underground. [0079] In one embodiment, the chloride is Cl₂. In another embodiment, the chloride is HOCl. In [0080] In another embodiment, the chloride is ClO₄-. [0081] In another embodiment, the metal salt is magnesium chloride. [0082] In another embodiment, the magnesium chloride is MgCl2. [0083] In another embodiment, the metal salt is calcium chloride. [0084] In another embodiment, the calcium chloride is CaCl2. [0085] In another embodiment, the metal salt is iron chloride. [0086] In another embodiment, the calcium chloride is FeCl₃. 302853711.1 [0087] In another embodiment, the hydrogen chloride is HCl. [0088] In some embodiments, the present technology provides a method of extracting bromine from geological formations that comprise bromides. The injection of chlorine, or aqueous chlorine into such formations causes the reaction of chlorine with bromide anion to form bromine monochloride as shown in reaction q. The bromine monochloride then reacts with another bromide anion to form chloride anion and bromine via reaction r. The bromine may be solubilized in water which is naturally present in the geological formation, or that has been injected along with the chlorine according to equation s. The bromine laden water may then be brought to the surface under its own pressure, or by a pump, and the bromine separated from the water by the reverse of reaction s. [0089] Chloride sequestration reaction equations: a. Cl2 + H2O → O2 + 2HCl + → + + for

or a g. Cl2 + 2Fe(II)Cl2 → 2Fe(III)Cl3 →

302853711.1 [0090] Mineral decomposition reaction equations: u. 2HCl + CaCO3 → CaCl2 + CO2 + H2O v. 2HCl + MgCO3 → MgCl2 + CO2 + H2O w. Generally, for monovalent metals, for divalent metals, 2HCl + M2CO3 → 2MCl ⁺ CO₂ for divalent metals, 2HCl + MCO₃ → MCl₂ + CO₂, and for trivalent metals, 6HCl + M₂(CO₃)₃ → 2MCl₃ + 3CO₂ where M = Mg, Ca, Sr, Ba, Fe, Mn, Zn, Al, Ti, Ni, Cu, Zr, or a combination thereof x. 4HCl + Mg₂SiO₄ → 2MgCl₂ + 2H₂O + SiO₂ y. 2HCl + Fe(II)O → Fe(II)Cl2 + H2O 302853711.1

Claims

CLAIMS: 1. A method of chloride sequestration comprising: a) identifying a hypoxic geological formation; b) creating a new, or identifying an existing access point in the geological formation; and c) injecting chloride into the access point. 2. The method of claim 1, further comprising capping the access point. 3. The method of claim 1 or 2, further comprising after step a), a step of identifying a hypoxic aquifer. 4. The method of any one of claims 1 to 3, wherein the chloride is Cl2. 5. The method of any one of claims 1 to 3, wherein the chloride is HOCl. 6. The method of any one of claims 1 to 3, wherein the chloride is ClO4-. 7. The method of any one of claims 1 to 6, wherein the step of creating a new, or identifying an existing access point in the geological formation is identifying a hypoxic geological formation bearing metal hydroxide, oxide, or carbonate deposits. 8. The method of claim 7, further comprising after step c), a step of injecting water into the access point, thus forming a solution of converted metal chloride salt. 9. The method of claim 8, further comprising after injecting water into the access point, removing the converted metal chloride salt solution from the access point. 10. The method of claim 8 or 9, wherein the metal chloride salt is MgCl2. 11. The method of any one of claims 1 to 10, wherein the chloride is reacted with hydrogen to form hydrogen chloride and heat of combustion. 12. The method of claim 11, wherein the hydrogen chloride is HCl. 302853711.1