Wastewater treatment systems and methods using activated bauxite residue (ABR)

Abstract

The compositions, systems and methods of the present disclosure include activated bauxite residue (ABR) compositions and methods of manufacturing activated bauxite residue compositions, methods of treating wastewater and / or soil (including water contained in soil) and methods of treating wastewater and / or soil containing an at least one pollutant, such as PFAS. In one embodiment disclosed herein, there is a method for producing activated mineral oxide, the method comprising reducing an iron oxide using carbon at a threshold temperature. The method can produce activated bauxite residue comprising Fe3O4, which can be used for the reduction of at least one pollutant, such as PFAS, in water or soil. In one embodiment, the method comprises producing activated mineral oxide by reducing moisture in at least one mineral oxide, combining the at least one mineral oxide with carbon to form a mixture, and heating the mixture to produce the activated mineral oxide.

Description

WASTEWATER TREATMENT SYSTEMS AND METHODS USING ACTIVATED BAUXITE RESIDUE (ABR)FIELD

[0001] The present disclosure relates to the field of treatment of pollutants in wastewater and soil and, in particular, to particular compositions for use in the treatment of such pollutants.BACKGROUND

[0002] Treating wastewater and soil, including wastewater that includes oil sands process-affected water (OSPW) and municipal wastewater as well as water and soil containing per-and polyfluoroalkyl substances (PFAS), can be difficult. Attempts at treatment may be inefficient or less than optimal. Various pollutants can remain in the wastewater or soil and affect environmental conditions and wildlife, as well as impair use of the same in subsequent applications.SUMMARY OF PARTICULAR EMBODIMENTS

[0003] It will be appreciated by those skilled in the art that other variations of the embodiments described below may also be practiced without departing from the scope. Further note, these embodiments, and other embodiments will become more fully apparent from a review of the description and claims which follow.

[0004] As described herein, the compositions, systems and methods of the present disclosure include (but are not limited to) the following: activated bauxite residue (ABR) compositions and methods of manufacturing activated bauxite residue compositions; methods of treating wastewater and / or soil (including water contained in soil); methods of treating wastewater and / or soil containing PFAS; methods of treating wastewater and / or soil to remove and / or neutralize PFAS; methods of treating wastewater and / or soil to remove contaminants therein; methods of treating wastewater and / or soil using activated bauxite residue compositions; use of activated bauxite residue compositions in wastewater and / or soil treatment applications; systems and processes for selective reduction of hematiteto magnetite in bauxite residue to create effective adsorption media for use in the removal of PFAS (and other contaminants) from water and soil; systems and processes for treating “forever chemicals” with recycled industrial waste in a closed loop system; and activated bauxite residue for use in pollutant removal applications in water and soil.

[0005] In accordance with an aspect, there is provided a method for producing activated mineral oxide, the method comprising reducing moisture in at least one mineral oxide; combining the at least one mineral oxide with carbon to form a mixture; and heating the mixture to produce the activated mineral oxide.

[0006] In some embodiments, the at least one mineral oxide comprises bauxite residue.

[0007] In some embodiments, the at least one mineral oxide comprises 5-60% Fe20s, 5-30% AI2O3, 0-15% TiO2, 2-14% CaO, 3-50% SiO2, and 1-10% Na2O.

[0008] In some embodiments, the bauxite residue is generated using a Bayer method in the extraction of alumina from bauxite.

[0009] In some embodiments, moisture is reduced by drying.

[0010] In some embodiments, moisture content in the at least one mineral oxide is at 5%.

[0011] In some embodiments, moisture content in the at least one mineral oxide is below 5%.

[0012] In some embodiments, the carbon is combined with the at least one mineral oxide in a quantity of 5% by volume.

[0013] In some embodiments, the mixture is heated to 1124°F.

[0014] In some embodiments, the mixture is heated to at least 1124°F.

[0015] In some embodiments, the mixture is heated to a temperature in a range from at least 1124°F.

[0016] In some embodiments, the mixture is heated to a temperature in a range from about 1100°F to about 1200°F.

[0017] In some embodiments, the mixture is heated to a temperature in a range from about 1124°F to about 1150°F.

[0018] In some embodiments, the mixture is heated in an atmosphere controlled rotary kiln.

[0019] In some embodiments, the combining and the heating is by mixing using stirring at a threshold temperature.

[0020] In some embodiments, the threshold temperature is 1124°F.

[0021] In some embodiments, the threshold temperature is at least 1124°F.

[0022] In some embodiments, the threshold temperature is in a range from at least about 1124°F.

[0023] In some embodiments, the threshold temperature is in a range from about 1100°F to about 1200°F.

[0024] In some embodiments, the threshold temperature is in a range from about 1124°F to about 1150°F.

[0025] In some embodiments, the combining comprises a partial reduction of hematite in the at least one mineral oxide to magnetite.

[0026] In some embodiments, the carbon comprises gaseous CO.

[0027] In some embodiments, the partial reduction causes a change in a crystal structure of the at least one mineral oxide, release of a gaseous species, and formation of a porous surface structure in the at least one mineral oxide.

[0028] In some embodiments, the heating increases a porous surface area of the at least one mineral oxide.

[0029] In some embodiments, the heating alters a meso and macro porous structure of the at least one mineral oxide by converting AI2O3 to a trigonal or hexagonal crystal system and converting hematite of the at least one mineral oxide to magnetite.

[0030] In some embodiments, a pH of the mixture is reduced.

[0031] In some embodiments, the pH of the mixture is reduced to about 10.

[0032] In some embodiments, the pH of the mixture is reduced by the heating comprising removing hydroxyls from the mixture.

[0033] In accordance with an aspect, there is provided an activated mineral oxide comprising a partially reduced iron species, the activated mineral oxide adapted to adsorb polar organic compounds by electrostatic interaction at pH greater than 3.

[0034] In some embodiments, the activated mineral oxide comprises a photocatalytic semiconductor when used with a UV light.

[0035] In some embodiments, the activated mineral oxide comprises a meso and macro porous structure.

[0036] In some embodiments, the activated mineral oxide comprises activated bauxite residue.

[0037] In some embodiments, the activated mineral oxide comprises FesCh, AI2O3, TiCh, SiCh, and carbon.

[0038] In some embodiments, moisture content in the mineral oxide is at 5%.

[0039] In some embodiments, moisture content in the mineral oxide is below 5%.

[0040] In some embodiments, the activated mineral oxide comprises carbon combined with the activated mineral oxide in a quantity of 5% by volume.

[0041] In some embodiments, the activated mineral oxide has been heated to 1124°F.

[0042] In some embodiments, the activated mineral oxide has been heated to at least 1124°F.

[0043] In some embodiments, the activated mineral oxide has been heated to a temperature in a range from at least about 1124°F.

[0044] In some embodiments, the activated mineral oxide has been heated to a temperature in a range from about 1100°F to about 1200°F.

[0045] In some embodiments, the activated mineral oxide has been heated to a temperature in a range from about 1124°F to about 1150°F.

[0046] In some embodiments, the activated mineral oxide comprises magnetite.

[0047] In some embodiments, the activated mineral oxide comprises a porous surface structure.

[0048] In some embodiments, the activated mineral oxide comprises A12O3 in a trigonal crystal system.

[0049] In some embodiments, the activated mineral oxide comprises A12O3 in a hexagonal crystal system.

[0050] In some embodiments, the activated mineral oxide comprises TiCh and the activated mineral oxide is positively charged.

[0051] In some embodiments, the activated mineral oxide comprises a pH of about 10.

[0052] In some embodiments, the activated mineral oxide does not contain hydroxyls.

[0053] In some embodiments, the activated mineral oxide comprises FesCh.

[0054] In some embodiments, the activated mineral oxide comprises activated bauxite residue comprising FesCh.

[0055] In some embodiments, the activated mineral oxide comprises a porous surface structure that is increased in area compared to an unactivated mineral oxide.

[0056] In accordance with an aspect, there is provided a method for producing an activated mineral oxide, the method comprising converting Fe20s to FesCh by mixing the Fe20s with about 5% carbon by weight and heating the Fe20s and the carbon to a temperature of at least 1124°F.

[0057] In some embodiments, at least a portion of the activated mineral oxide is positively charged.

[0058] In some embodiments, the activated mineral oxide has a greater porous surface area than the Fe2C>3 before the heating.

[0059] In some embodiments, the activated mineral oxide has a pH of about 10.

[0060] In some embodiments, the activated mineral oxide is adapted to remove fluorine compounds from water.

[0061] In some embodiments, the fluorine compounds comprise per-alkyls.

[0062] In some embodiments, the fluorine compounds comprise poly-alkyls.

[0063] In some embodiments, the activated mineral oxide is adapted to remove fluorine compounds from soil.

[0064] In some embodiments, the fluorine compounds comprise per-alkyls.

[0065] In some embodiments, the fluorine compounds comprise poly-alkyls.

[0066] In some embodiments, use of the activated mineral oxide is for the reduction of at least one pollutant in water.

[0067] In some embodiments, the at least one pollutant comprises at least one PF AS.

[0068] In some embodiments, the at least one pollutant comprises an organic polar molecule.

[0069] In some embodiments, the use includes an adsorption mechanism for the reduction.

[0070] In some embodiments, the adsorption mechanism comprises electrostatic interaction.

[0071] In some embodiments, the adsorption mechanism comprises hydrophonic interaction.

[0072] In some embodiments, the adsorption mechanism comprises ligan exchange.

[0073] In some embodiments, the adsorption mechanism comprises hydrogen bonding.

[0074] In some embodiments, use of the activated mineral oxide is for for the reduction of at least one pollutant in soil.

[0075] In some embodiments, the at least one pollutant comprises at least one PF AS.

[0076] In some embodiments, the at least one pollutant comprises an organic polar molecule.

[0077] In some embodiments, an adsorption mechanism for the reduction.

[0078] In some embodiments, the adsorption mechanism comprises electrostatic interaction.

[0079] In some embodiments, the adsorption mechanism comprises hydrophonic interaction

[0080] In some embodiments, the adsorption mechanism comprises ligan exchange.

[0081] In some embodiments, the adsorption mechanism comprises hydrogen bonding.

[0082] In some embodiments, use of the activated mineral oxide is for neutralizing an acid content of water.

[0083] In some embodiments, use of the activated mineral oxide is for neutralizing an acid content of soil.

[0084] In accordance with an aspect, there is provided a method for producing activated mineral oxide, the method including reducing an iron oxide using carbon at a threshold temperature.

[0085] In some embodiments, the threshold temperature is 1124°F.

[0086] In some embodiments, the mineral oxide comprises bauxite residue.

[0087] In some embodiments, the iron oxide is Fe20s.BRIEF DESCRIPTION OF THE DRAWINGS

[0088] These and other features will become more apparent in the following detailed description in which reference is made to the appended drawings.

[0089] FIG. 1 is a graph showing a percentage of removal of pollutant, in accordance with some embodiments;

[0090] FIG. 2 is a flowchart showing a method for using activated bauxite residue, in accordance with some embodiments;

[0091] FIG. 3 A is a graph showing the removal efficiency of PFAS compounds for activated bauxite residue and for activated carbon, in accordance with some embodiments; and

[0092] FIG. 3B is a graph showing the removal efficiency of PFAS compounds for activated bauxite residue and for activated carbon, in accordance with some embodiments.DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0093] In this respect, before explaining at least one embodiment in detail, it is to be understood that embodiments are not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. Other embodiments are capable of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. In particular, all terms used herein are used in accordance with their ordinary meanings unless the context or definition clearly indicates otherwise. Also, unless indicated otherwise except within the claims the use of “or” includes “and” and vice-versa. Non-limiting terms are not to be construed as limiting unless expressly stated or the context clearly indicates otherwise (for example, “including”, “having”, “characterized by” and “comprising” typically indicate “including without limitation”). Singular forms included in the claims such as “a”, “an” and “the” include the plural reference unless expressly stated or the context clearly indicates otherwise. Further, the stated features and / or configurations or embodiments thereof the suggested intent may be applied as seen fit to certain operating conditions or environments by one experienced in the field of art.

[0094] In some embodiments, there is described a product composition and process for treating industrial waste, which utilizes a material with unique properties to remove another significant pollutant from water and soil on a global scale, all while providing a ‘closed loop’ system for disposal of these pollutants.

[0095] In some example embodiments, the process begins with the selective reduction of a widely available waste compound from the aluminum industry, known as bauxite residue (or “BR”). Bauxite residue is a mineral oxide compound waste generated utilizing the Bayer process in the extraction of alumina from bauxite in the manufacturing of aluminum.

[0096] The primary oxide species in bauxite residue is Fe2C>3 (or “Hematite”), a common iron oxide compound, but consists of approximately 20 different oxides of varied content with the top 6 oxides being iron, aluminum, titanium, calcium, sodium, and silicon.Typical analysis of Bauxite Residue:Chemical Percentage compositionFe2O3 5-60%A12O3 5-30%TiO2 0-15%CaO 2-14%SiO2 3-50%Na2O 1-10%

[0097] Bauxite residue is considered ‘hazardous’ as the pH is typically 12 or higher. As such, bauxite residue material is typically stored in dedicated reservoirs or containment ponds around the world at the site of processing. It is estimated that there are over 4 billion tons of legacy bauxite residue stored at these sites with hundreds of millions of new tons being added and stored each year. Accordingly, a need exists to curb or reduce bauxite residue stores around the world.

[0098] In some embodiments, there is described a system and process for manufacturing an activated bauxite residue composition using bauxite residue as a base component. In one embodiment of a process, bauxite residue is dried in order to remove (or reduce) moisture content therein. In one embodiment, once the moisture content of the bauxite residue is low enough (e.g., at or around 5%, or below 5%), then the bauxite residue is combined with a quantity of carbon (e.g., 5% by volume) in a mixture. The mixture is then heated. In one preferred embodiment, the mixture is put into an atmosphere controlled rotary kiln and heated to a temperature (or internal temperature) of 1124°F, or minimum temperature of 1124°F. Heating and mixing can also be accomplished by mechanized or magnetic stirring at high temperatures, including via the use of a continuous furnace, such as a rotary hearth, rotary kiln, traveling bed, shaft furnace or other suitable apparatus. In one embodiment, the mixture is heated to a temperature in the range of approximately 900 - 1200°F. In another embodiment, the mixture is heated to a temperature in the range of approximately 1100°F - 1200°F or higher. In yet another embodiment, the mixture is heated to a temperature in the range of approximately 1124°F - 1150°F. In another embodiment, the mixture is heated to a temperature in the range of at leastapproximately 1124°F. In some embodiments, the moisture is reduced by drying. In some embodiments, the moisture is reduced by filter pressing. In some embodiments, the moisture is reduced by centrifuge. Other moisture reducing methods can be used in various embodiments.

[0099] The addition of carbon results in partial reduction of hematite to magnetite based on the reactions listed below. Alternative reductants such as gaseous CO can also be used for the reduction reaction.Fe20s + C = FesO4 + COCO + O2= CO2

[0100] Solid state reduction of hematite to magnetite results in a change in the crystal structure causing the release of gaseous species and formation of porous surface structure with high specific surface area.

[0101] The heating of the material (as described above) (e.g., in the rotary kiln) also increases the porous surface area of the input material, altering the meso / macro porous structure of the material through conversion of AI2O3 to the trigonal or hexagonal crystal system (Corundum) and conversion of hematite to magnetite.

[0102] As a result of the process steps described herein, the pH of the mixture is also reduced (e.g. pH reduction to approx. 10), rendering the output material non-hazardous to handle. The reduction in pH occurs as the heat process removes hydroxyls left over from the Bayer process.

[0103] Activated bauxite residue produced in accordance with the processes described herein can be utilized in wastewater and soil treatment applications to remove harmful pollutants therefrom, including PF AS.

[0104] In one embodiment, ABR produced in accordance with the processes described herein can be used to remove PFAS from contaminated water or soil, using, for example, an adsorption mechanism, such as electrostatic interaction, hydrophonic interaction, ligan exchange, and / or hydrogen bond.

[0105] Importantly, use of ABR to treat wastewater or contaminated soil, instead of common adsorbents, such as activated carbon, represents a more cost effective, efficient and higher capacity method of treating wastewater and soil, including for use in PF AS removal applications.

[0106] In an example embodiment of an adsorption process for removing PF AS from contaminated water or soil, the starting material is a compound comprised of multiple mineral oxides that include: FesO4, AI2O3, TiC>2, SiC>2, and carbon.

[0107] By partially reducing the iron species of the compound, at least two benefits occur: a. Partially reducing the iron species content of the base material to magnetite (FesC ), renders that content magnetic. The material acts as a ‘semiconductor’ and adsorption is enhanced from the electrostatic force from the surface charge of the material. i. Surface charge of ABR promotes the removal of polar organic compounds from wastewater through electrostatic interaction. ii. Given that the PF AS compounds are anionic (negatively charged at pH > 3), an electrostatic interaction occurs with the cations present in the ABR (Al3+for example) that provides an attraction and adsorption function in the collection of organic and heavy metal compounds. iii. Because of the TiO2 content in the ABR and with the material being (+) charged, when used with a UV light, the ABR also acts as a photocatalytic semiconductor. b. The enhanced porous surface area created during the iron species reduction of the material increases the ‘meso’ and ‘macro” porous structure aiding with the sorption capacity of organics and (others) from water.

[0108] The pH of ABR produced in accordance with the processes described herein is approximately 10. Accordingly, for applications requiring treatment of acidic wastewater or acidic soil, ABR provides an opportunity to balance the pH and neutralize the acid content of the wastewater or soil.

[0109] In some example embodiments, a process is described for transforming Fe2C>3 to FesC via a partial reduction reaction which is accomplished by adding ~5% carbon (C) to the mixture prior to introducing the material to the controlled atmosphere kiln. A partial reduction of the material occurs at a minimum temperature of 1124°F in the controlled atmosphere, transforming the Fe2C>3 to FesC with CO as a byproduct, pursuant to the following chemical reaction: Fe2O3 + C = Fe3O4 + CO.

[0110] This partial or “selective” reduction has several effects, including but not limited to: a. The conversion of the hematite to magnetite makes the bulk of the material (+) charged (magnetic). b. The partial reduction or ‘roasting’ of the oxides increases the porous surface area of the material, increasing its sorption characteristics. c. The process reduces the pH of the starting material from 12 or more to around 10, making it safe and manageable to handle, while preserving a pH level to be useful in water treatment applications that warrant a need for a media with a high pH.

[0111] In a use application, the partially reduced or “activated” BR (or ABR), produced in accordance with the present disclosure, can be utilized to remove certain contaminants from water and soil, including but not limited to fluorine compounds (such as perfluorocarbons (or PFCs)). PFCs are a group of thousands of man-made carbon and fluorine chemicals. They are categorized as “forever chemicals” as the F-C bond is very strong, which makes PFC’s extremely persistent and difficult to break down.

[0112] A subcategory of fluorine compounds are the per- and poly-alkyls, which include F-C chains attached to carboxylic (R-C(=O)OH) or sulfonic acid (R-S(=O)2-OH “heads”. Sulfonic acids (which are basically an organic form of sulfuric acid) are as much as one million times stronger than their carboxyl counterparts. Longer chains are generally more toxic than short chains. Left instorage, short chain PFCs tend to recombine to become longer chains (and therefore become more toxic).

[0113] Many present day research and development efforts are focused on PFAS (perfluorooctanoic sulfonate) and PFOS (perfluorooctanoate) clean-up and remediation. The ABR composition produced in accordance with the present disclosure is effective in removing PFOS and PFAS from water using conventional water treatment processes which incorporate the ABR composition.

[0114] In some embodiments, various advantages are provided by the activated mineral oxide (e.g., activated bauxite residue) described herein. For example, a unique mineral oxide can be manufactured as an adsorbent product made from recycled bauxite residue, which is a hazardous / toxic waste from the aluminum industry. This can provide environmental and waste reduction advantages. For example, there is presently over 4 billion tons on reserve at dedicated sites and growing every day.

[0115] In some embodiments, activated bauxite residue is a product similar to activated carbon, yet has shown to be more effective (up to 100% in many cases) in removing challenging contaminants such as PFAS, heavy metals and other organic / in-organic compounds from water. FIG. 3A and 3B show data collected from experiments that show that ABR outperforms activated carbon (PAC) in its removal efficiency for various types of PFAS compounds, according to some embodiments of ABR described herein. In FIG. 3 A, the top bar for each of the three PFAS compounds shown refers to a treatment of 0.1 g / L PAC + 500 ng / L PFAS, while the bottom bar refers to a treatment of 10 g / L ABR + 500 ng / L PFAS. In FIG. 3B, the top, middle, and bottom bars for each of the PFAS compounds shown refer to treatments of 100 g / L ABR, 50 g / L ABR, and 0.1 g / L PAC, each for 24 hours, respectively.

[0116] In some embodiments, a further advantage provided is that activated carbon products can be produced from materials generating large amounts of CO2 emissions, while ABR can be produced with 97.5% lower CO2 emissions, creating carbon credits.

[0117] In some embodiments, activated carbon products need to be ‘regenerated’ after use (e.g., burning off the adsorbed contaminant(s) - causing added emissions that are currently unregulated), but can only be regenerated two to three times before they end up in a landfill. By comparison, ABR inaccordance with some embodiments described herein can be collected and recycled post water treatment use in a secondary process to permanently destroy the contaminant, creating additional revenue that offset costs and provided usable metallic iron and aggregate products.

[0118] Furthermore, numerous locations of red mud sites around the world may provide unlimited supplies for the manufacture of ABR and provide logistical and availability benefits for its use to address global water issues.

[0119] In some embodiments, ABR provides a true circular economy solution that not only provides a source of carbon credits while utilizing a ‘waste to clean a waste’, eliminates waste and reduces contingent liabilities for aluminum companies, addresses global clean water needs, and satisfies five targeted UN Sustainable Development Goals (SDGs).

[0120] To gain a better understanding of embodiments described herein, the following examples are set forth. It will be understood that these examples are intended to describe illustrative embodiments and are not intended to limit the scope of embodiments in any way.EXAMPLESEXAMPLE 1:

[0121] As shown in FIG. 1 and described herein, recent bench-scale testing using ABR for the removal of long and short chain PF AS compounds from water produced the following outcomes.

[0122] As indicated in FIG. 1, ABR was used in a water treatment process for effecting removal of several PF AS compounds ranging from short- to long-chain substances. Long chain PFAS compounds are well removed by ABR (up to 100%) and short-chain PFAS compounds (e.g., PFBA) were not removed as well (-20%). Enhanced PFAS removal using ABR was observed in concentrations around 100 g / L although there were no differences in longer-chain PFAS removal at higher concentrations of ABR. Background PFAS levels were deemed to be 23 ppt which does not influence the analytical detection at higher concentrations (i.e., 600 ppt). Depending on the treatment goal (e.g., S 70 ppt), ABR treatment can be further optimized. For this particular experiment, the initial sum EPF AS was 5,710ppt and after treatment, the EPF AS dropped to 782 ppt at 100 g / L ABR dose, with PFBA and PFPeA contributing almost 50% of the total concentration in the treated soltuion. If these two short-chain PF AS were not considered in the analysis, excellent removals of longer-chain PFAS were evident (<20 ng / L after 24h treatment) upon treatment with ABR, and were deemed lower than the background levels.

[0123] Activated bauxite residue in the form produced in accordance with the present disclosure appears to be materially more effective in water and soil treatment / remediation applications than activated carbon (AC), particularly with respect to removal of longer chain PFCs from the water (or soil) which are the more toxic ones.

[0124] The activated bauxite residue composition described herein can be used in connection with a form of “closed loop” treatment process wherein the method of disposal takes the spent ABR and introduces it into a process to reduce the oxide content of the main oxide content (i.e. iron oxide) to metallic iron (in the collectable form of “Pig Iron”) and vitrifies and encapsulates the remaining oxides and the contained heavy metals and other contaminants) in a reusable, non-leaching slag. This slag can be ground and sold as roadbed and for other engineered aggregate applications. FIG. 2 shows an example closed loop process, according to some embodiments.

[0125] The ABR composition produced in accordance with the processes described herein is not technically produced by “calcining” the bauxite residue in the true meaning of the term calcination. In this regard, while a “calciner” apparatus can be employed as part of the process to convert BR to ABR, the BR material is not “calcined” in the true sense of the word. By definition, “calcining” is the close of weight of something by evaporating something in a vapor. In some embodiments, in the processes described herein, the iron oxide species in the bauxite residue are at least partially reduced (by converting it from hematite to magnetite) while using a rotary kiln (or similar apparatus) that may resemble a calciner in form or function. Also, technically, the calcination process tends to close the pores of material that is subject to calcination. In contrast, the processes for production of ABR described herein increase the porous structure of the BR material, according to some embodiments. In some embodiments, reference to “activated bauxite residue” in FIG. 2 refers to activated bauxite residueprepared in accordance with methods described herein and not “calcined” in the true meaning of the term calcination.

[0126] The scope of this disclosure encompasses all changes, substitutions, variations, alterations, and modifications to the example embodiments described or illustrated herein that a person having ordinary skill in the art would comprehend. The scope of this disclosure is not limited to the example embodiments described or illustrated herein. Moreover, although this disclosure describes and illustrates respective embodiments herein as including particular components, elements, functions, operations, or steps, any of these embodiments may include any modification, combination or permutation of any of the components, elements, functions, operations, or steps described or illustrated anywhere herein that a person having ordinary skill in the art would comprehend. All such modifications, combinations and permutations are believed to be within the sphere and scope of the embodiments.

Claims

CLAIMSWhat is claimed is:

1. A method for producing activated mineral oxide, the method comprising a. reducing moisture in at least one mineral oxide; b. combining the at least one mineral oxide with carbon to form a mixture; and c. heating the mixture to produce the activated mineral oxide.

2. The method of claim 1, wherein the at least one mineral oxide comprises bauxite residue.

3. The method of claim 1 or 2, wherein the at least one mineral oxide comprises 5-60% Fe20s, 5- 30% AI2O3, 0-15% TiO2, 2-14% CaO, 3-50% SiO2, and 1-10% Na2O.

4. The method of claim 2, wherein the bauxite residue is generated using a Bayer method in the extraction of alumina from bauxite.

5. The method of any one of claims 1 to 4, wherein moisture is reduced by drying.

6. The method of any one of claims 1 to 5, wherein moisture content in the at least one mineral oxide is at 5%.

7. The method of any one of claims 1 to 6, wherein moisture content in the at least one mineral oxide is below 5%.

8. The method of any one of claims 1 to 7, wherein the carbon is combined with the at least one mineral oxide in a quantity of 5% by volume.

9. The method of any one of claims 1 to 8, wherein the mixture is heated to 1124°F.

10. The method of any one of claims 1 to 8, wherein the mixture is heated to at least 1124°F.

11. The method of any one of claims 1 to 8, wherein the mixture is heated to a temperature in arange from at least about 1124°F.

12. The method of any one of claims 1 to 8, wherein the mixture is heated to a temperature in a range from about 1100°F to about 1200°F.

13. The method of any one of claims 1 to 8, wherein the mixture is heated to a temperature in a range from about 1124°F to about 1150°F.

14. The method of any one of claims 1 to 13, wherein the mixture is heated in an atmosphere controlled rotary kiln.

15. The method of any one of claims 1 to 14, wherein the combining and the heating is by mixing using stirring at a threshold temperature.

16. The method of any one of claims 1 to 15, wherein the threshold temperature is 1124°F.

17. The method of any one of claims 1 to 15, wherein the threshold temperature is at least 1124°F.

18. The method of any one of claims 1 to 15, wherein the threshold temperature is in a range from at least about 1124°F.

19. The method of any one of claims 1 to 15, wherein the threshold temperature is in a range from about 1100°F to about 1200°F.

20. The method of any one of claims 1 to 15, wherein the threshold temperature is in a range from about 1124°F to about 1150°F.

21. The method of any one of claims 1 to 20, wherein the combining comprises a partial reduction of hematite in the at least one mineral oxide to magnetite.

22. The method of any one of claims 1 to 21, wherein the carbon comprises gaseous CO.

23. The method of claim 21, wherein the partial reduction causes a change in a crystal structure of the at least one mineral oxide, release of a gaseous species, and formation of a porous surfacestructure in the at least one mineral oxide.

24. The method of any one of claims 1 to 23, wherein the heating increases a porous surface area of the at least one mineral oxide.

25. The method of any one of claims 1 to 24, wherein the heating alters a meso and macro porous structure of the at least one mineral oxide by converting AI2O3 to a trigonal or hexagonal crystal system and converting hematite of the at least one mineral oxide to magnetite.

26. The method of any one of claims 1 to 25, wherein a pH of the mixture is reduced.

27. The method of claim 26, wherein the pH of the mixture is reduced to about 10.

28. The method of claim 26, wherein the pH of the mixture is reduced by the heating comprising removing hydroxyls from the mixture.

29. An activated mineral oxide comprising a partially reduced iron species, the activated mineral oxide adapted to adsorb compounds.

30. The activated mineral oxide of claim 29, wherein the activated mineral oxide comprises a photocatalytic semiconductor when used with a UV light.

31. The activated mineral oxide of claim 29 or 30, wherein the activated mineral oxide comprises a meso and macro porous structure.

32. The activated mineral oxide of any one of claims 29 to 31, wherein the activated mineral oxide comprises activated bauxite residue.

33. The activated mineral oxide of any one of claims 29 to 32, wherein the activated mineral oxide comprises FesCh, AI2O3, TiCh, SiC>2, and carbon.

34. The activated mineral oxide of any one of claims 29 to 33, wherein moisture content in the mineral oxide is at 5%.

35. The activated mineral oxide of any one of claims 29 to 34, wherein moisture content in the mineral oxide is below 5%.

36. The activated mineral oxide of any one of claims 29 to 35, wherein the activated mineral oxide comprises carbon combined with the activated mineral oxide in a quantity of 5% by volume.

37. The activated mineral oxide of any one of claims 29 to 36, wherein the activated mineral oxide has been heated to 1124°F.

38. The activated mineral oxide of any one of claims 29 to 37, wherein the activated mineral oxide has been heated to at least 1124°F.

39. The activated mineral oxide of any one of claims 29 to 38, wherein the activated mineral oxide has been heated to a temperature in a range from at least about 1124°F.

40. The activated mineral oxide of any one of claims 29 to 38, wherein the activated mineral oxide has been heated to a temperature in a range from about 1100°F to about 1200°F.

41. The activated mineral oxide of any one of claims 29 to 38, wherein the activated mineral oxide has been heated to a temperature in a range from about 1124°F to about 1150°F.

42. The activated mineral oxide of any one of claims 29 to 41, wherein the activated mineral oxide comprises magnetite.

43. The activated mineral oxide of any one of claims 29 to 42, wherein the activated mineral oxide comprises a porous surface structure.

44. The activated mineral oxide of any one of claims 29 to 43, wherein the activated mineral oxide comprises A12O3 in a trigonal crystal system.

45. The activated mineral oxide of any one of claims 29 to 44, wherein the activated mineral oxide comprises A12O3 in a hexagonal crystal system.

46. The activated mineral oxide of any one of claims 29 to 45, wherein the activated mineral oxidecomprises TiCh and the activated mineral oxide is positively charged.

47. The activated mineral oxide of any one of claims 29 to 46, wherein the activated mineral oxide comprises a pH of about 10.

48. The activated mineral oxide of any one of claims 29 to 47, wherein the activated mineral oxide does not contain hydroxyls.

49. The activated mineral oxide of any one of claims 29 to 48, wherein the activated mineral oxide comprises Fe3C>4.

50. The activated mineral oxide of any one of claims 29 to 49, wherein the activated mineral oxide comprises activated bauxite residue comprising Fe3C>4.

51. The activated mineral oxide of any one of claims 29 to 50, wherein the activated mineral oxide comprises a porous surface structure that is increased in area compared to an unactivated mineral oxide.

52. The activated mineral oxide of any one of claims 29 to 51, wherein the activated mineral oxide is adapted to adsorb polar organic compounds by electrostatic interaction at pH greater than 3.

53. The activated mineral oxide of any one of claims 29 to 52, wherein the activated mineral oxide is adapted to adsorb at least one PF AS.

54. A method for producing an activated mineral oxide, the method comprising converting Fe2O3to Fe3O4by mixing the Fe2O3with about 5% carbon by weight and heating the Fe2O3and the carbon to a temperature of at least 1124°F.

55. The method of claim 54, wherein at least a portion of the activated mineral oxide is positively charged.

56. The method of claim 54 or 55, wherein the activated mineral oxide has a greater porous surface area than the Fe2O3before the heating.

57. The method of any one of claims 54 to 56, wherein the activated mineral oxide has a pH of about 10.

58. The method of any one of claims 54 to 57, wherein the activated mineral oxide is adapted to remove fluorine compounds from water.

59. The method of claim 58, wherein the fluorine compounds comprise per-alkyls.

60. The method of claim 58, wherein the fluorine compounds comprise poly-alkyls.

61. The method of any one of claims 54 to 60, wherein the activated mineral oxide is adapted to remove fluorine compounds from soil.

62. The method of claim 61, wherein the fluorine compounds comprise per-alkyls.

63. The method of claim 61, wherein the fluorine compounds comprise poly-alkyls.

64. Use of the activated mineral oxide of claims 29 to 53 for the reduction of at least one pollutant in water.

65. The use of claim 64, wherein the at least one pollutant comprises at least one PF AS.

66. The use of claim 64 or 65, wherein the at least one pollutant comprises an organic polar molecule.

67. The use of any one of claims 64 to 66, comprising an adsorption mechanism for the reduction.

68. The use of claim 67, wherein the adsorption mechanism comprises electrostratic interaction.

69. The use of claim 67 or 68, wherein the adsorption mechanism comprises hydrophonic interaction.

70. The use of any one of claims 67 to 69, wherein the adsorption mechanism comprises ligan exchange.

71. The use of any one of claims 67 to 70, wherein the adsorption mechanism comprises hydrogen bonding.

72. Use of the activated mineral oxide of claims 29 to 53 for the reduction of at least one pollutant in soil.

73. The use of claim 72, wherein the at least one pollutant comprises at least one PF AS.

74. The use of claim 72 or 73, wherein the at least one pollutant comprises an organic polar molecule.

75. The use of any one of claims 72 to 74, comprising an adsorption mechanism for the reduction.

76. The use of claim 75, wherein the adsorption mechanism comprises electrostratic interaction.

77. The use of claim 75 or 76, wherein the adsorption mechanism comprises hydrophonic interaction78. The use of any one of claims 75 to 77, wherein the adsorption mechanism comprises ligan exchange.

79. The use of any one of claims 75 to 78, wherein the adsorption mechanism comprises hydrogen bonding.

80. Use of the activated mineral oxide of claims 29 to 53 for neutralizing an acid content of water.

81. Use of the activated mineral oxide of claims 29 to 53 for neutralizing an acid content of soil.

82. A method for producing activated mineral oxide, the method comprising reducing an iron oxide using carbon at a threshold temperature.

83. The method of claim 82, wherein the threshold temperature is 1124°F.

84. The method of claim 82 to 83, wherein the mineral oxide comprises bauxite residue.

85. The method of any one of claims 82 to 83, wherein the iron oxide is Fe20s.

86. The method of any one of claims 1 to 28, wherein moisture is reduced by filter pressing.

87. The method of any one of claims 1 to 28, wherein moisture is reduced by centrifuge.

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