Improved pozzolan and methods of making and using same

Abstract

A process for producing a pozzolan from a starting material such as glass. The starting material is size-reduced and incorporated into an aqueous slurry to form a solid treated pozzolan and an alkali metal rich aqueous solution. The size-reduction can be carried out before or after incorporation into the aqueous slurry. The solid treated pozzolan is separated from the alkali metal rich aqueous solution, and gas containing carbon dioxide is supplied to the alkali metal rich aqueous solution for a treatment period to sequester carbon dioxide.

Description

IMPROVED POZZOLAN AND METHODS OF MAKING AND USING SAMECross-Reference to Related Applications

[0001] This application claims priority to, and the benefit of, United States provisional patent application No. 63 / 439,748 filed 18 January 2023, the entirety of which is incorporated by reference herein for all purposes.Technical Field

[0002] Some embodiments relate to systems and methods for improving properties of a pozzolan material. In some embodiments, the pozzolan material is glass. In some embodiments, the treated material is useful as a pozzolan or supplementary cementitious material in cement.Background

[0003] Concrete is a composite material incorporating aggregate material bonded together with a cement paste that hardens as it cures over time. To form concrete structures, the aggregate material is mixed with cement and water to form a slurry that can be molded to a desired shape. The cement reacts with water and other components of the mixture to form a hard matrix that binds the materials together into a durable stone-like material.

[0004] Concrete is the most widely used building material in the world. Significant greenhouse gas, including carbon dioxide (CO2), emissions are associated with the production of concrete, and in particular with cement used in the concrete. It is estimated that the production of cement (e.g. Portland cement) produces as much as 8% of the world’s greenhouse gas emissions.

[0005] Materials such as pozzolans (or supplementary cementitious materials) can be added to cement or concrete to improve the working properties of the mixture and / or the physical parameters of the finished material. Pozzolans can also help to reduce the production of greenhouse gases associated with the production of concrete, by reducing the amount of material such as Portland cement that must be used in the concrete. Glass is a type of pozzolan, although it can have certain undesirable properties when used as such.

[0006] Alkali-silica reactivity occurs when silica contained in certain aggregates reacts with alkali hydroxide in concrete (e.g. NaOH, KOH) to form a gel (e.g. sodium silicate) that is hygroscopic and that swells as it adsorbs water from the surrounding cement paste or from the external environment. As this gel expands, it can crack the concrete, potentially causing structural damage.

[0007] One of the potential downsides of using glass as a pozzolan is that it may not fully mitigate alkali-silica reactivity in concrete to below 0.10% expansion at 14 days in accordance with ASTM standards.

[0008] There is a general desire for improved pozzolans for use in the manufacture of concrete that can reduce the greenhouse gas emissions associated with concrete production, and methods of their production.

[0009] The foregoing examples of the related art and limitations related thereto are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.Summary

[0010] The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the abovedescribed problems have been reduced or eliminated, while other embodiments are directed to other improvements.

[0011] One aspect of the invention provides a process for producing a pozzolan from a starting material. The starting material is size-reduced in an aqueous slurry to a desired size to activate alkali metals in the starting material. In some aspects, the starting material is glass, including post-consumer waste glass. In some aspects, the glass is E-glass, flat glass, plate glass, glass bottles and / or glass jars, and / or windshields. In some aspects, the activated alkali metals, including e.g. sodium, are washed out of the glass in the aqueous slurry by removal of water, to improve performance characteristics of the pozzolan, such as by reducing alkali-silica reactivity and / or increasing compressive strength of a concrete product incorporating the treated pozzolan produced by the process.

[0012] In some aspects, the solid treated pozzolan is separated from the aqueous solution containing the activated alkali metals, for example by dewatering. A gas containing carbon dioxide is supplied to the aqueous solution for a treatment period to sequester carbon dioxide. The treated pozzolan product can be dried, and in some aspects is subjected to an acid washing and subsequent rinsing steps, further size homogenization and / or removal of undesirably large particles to produce a final pozzolan product for incorporation into cement and ultimately concrete.

[0013] In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following detailed descriptions.Brief Description of the Drawings

[0014] Exemplary embodiments are illustrated in referenced figures of the drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than restrictive.

[0015] FIG. 1 shows an example embodiment of a method for manufacturing a pozzolan from a starting material.

[0016] FIG. 2 shows a second example embodiment of a method for manufacturing a pozzolan from a starting material.

[0017] FIG. 3 shows a third example embodiment of a method for manufacturing a pozzolan from a starting material, using the pH of the reaction mixture to control the treatment period.

[0018] FIG. 4 shows an example embodiment of an apparatus for manufacturing a pozzolan from a starting material.

[0019] FIG. 5 shows a fourth example embodiment of a method for manufacturing a pozzolan from a starting material.

[0020] FIG. 6 shows a fifth example embodiment of a method for manufacturing a pozzolan from a starting material.Description

[0021] Throughout the following description specific details are set forth in order to provide a more thorough understanding to persons skilled in the art. However, well known elements may not have been shown or described in detail to avoid unnecessarily obscuring the disclosure. Accordingly, the description and drawings are to be regarded in an illustrative, rather than a restrictive, sense.

[0022] The inventors have now discovered a process of producing a pozzolan that results in both sequestration of greenhouse gases such as carbon dioxide during production of the pozzolan, and which also minimizes the alkali-silica reactivity of concrete produced with the pozzolan. In some aspects, alkali metals including sodium ions are removed from the pozzolan during the process.

[0023] More specifically a wet grinding process of a slurry of the starting material in water is carried out to activate alkali metals in the starting material for removal in aqueous solution. In some embodiments, the starting material is glass. Without being bound by theory, during this wet grinding process, sodium oxide (Na2O) in glass is activated and reacts with water to form sodium hydroxide (NaOH) and dissolves in solution. The NaOH solution can be separated from the starting material during dewatering and used for carbon capture via reaction with CO2, as carbonic acid (H2CO3), to form Na2COs in an aqueous environment. Thus the process can reduce alkali-silica reactivity of glass when used as a pozzolan by removing alkali metals such as sodium from the glass and thereby decreasing the alkalinity of the glass, as the sodium is removed from the pozzolan via a NaOH solution (i.e. the alkali metal rich solution). This process also sequesters some carbon dioxide via the formation of Na2COs. The carbonic acid will also react with any soluble calcium and magnesium ions, present in the alkali metal rich solution as calcium hydroxide (Ca(OH)2) and magnesium hydroxide (Mg(OH)2) to form calcium carbonate (CaCOs) and magnesium carbonate (MgCO3).

[0024] With reference to FIG. 1 , an example embodiment of a method 100 for producing an improved pozzolan is illustrated. At 102, a starting material is supplied. At 106, the starting material is combined with water to produce a mixture in the form of an aqueous slurry. At 104, the mixture is milled for a treatment period to size reduce the starting material, activating alkali metals in the starting material for reaction with water. At 108, the mixture isdewatered to yield the desired improved pozzolan product 114 and an aqueous solution 110 containing activated alkali metals reacted with water. In some embodiments if desired any suitable grinding aid can be added at 104 or 106.

[0025] At 112, a source of carbon dioxide is supplied to the aqueous solution obtained at 110. In some embodiments, the source of carbon dioxide is at atmospheric pressure. In some embodiments, the source of carbon dioxide is pressurized. In some embodiments, the carbon dioxide could be provided in combination with other gases, for example flue gases or other combustion gases that are unprocessed or only partially processed, and which may contain other oxidizing gases such as CO, SO2, SO3, NO, NO2, NO3, H2O and the like. CO2 or other gas is supplied to the alkali metal rich solution in any suitable contactor vessel, e.g. a sparger, a diffuser, a contactor tower, or the like. In some embodiments, the contactor tower is run with gas and solution in parallel or co-current flow. In some embodiments, the contactor tower is run with the gas and solution in counter or counter-current flow.

[0026] In some embodiments, the pressure of the gas that is added at step 112 is in the range of about 5 to about 150 psi gauge, including between about 20 to about 100 psi gauge, including any value or subrange therebetween, e.g. 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140 or 145 psi gauge. In some embodiments, the gas that is added at step 112 is supplied at atmospheric (i.e. ambient) pressure. The pressure at which the carbon dioxide is supplied could be adjusted by the person skilled in the art to remain within the maximum pressure limits of the apparatus being used to conduct the process, while still being high enough to dissolve a sufficient amount of carbon dioxide to yield a desired reaction profile.

[0027] In some embodiments, prior to carbon dioxide being supplied to the aqueous solution, the aqueous solution is concentrated at 115, for example using a membrane or distillation unit. Concentration step 115 increases the concentration of alkali hydroxide, e.g. NaOH, present in the aqueous solution prior to exposure to carbon dioxide.

[0028] In some embodiments, the starting material supplied at 102 is glass. In some embodiments, the starting material is glass diverted from a waste stream, e.g. postconsumer glass waste such as container glass such as glass bottles and jars e.g. mason jar glass, E-glass, flat glass or plate glass such as windshields, and the like. In someembodiments, the starting material is soda-lime glass. In some embodiments, the starting material is subjected to any suitable crushing or grinding process to render it suitable as a starting material before being used in method 100. For example, post-consumer glass waste may be received from consumers, processed to clean the glass, and crushed to a relatively uniform starting size, e.g. having average particle diameters of in the range of about 70 to about 110 microns, including any value or subrange therebetween e.g. about 75, 80, 85, 90, 95, 100, or 105 microns, including about 100 microns, before being used as a starting material in method 100.

[0029] In some embodiments, the starting material is supplied at 102 to a mill such as a tumbling ball mill, stirred bead mill, horizontal mill, vibratory kinetic mill, roller mill, or the like and the remaining steps 106 and 104 are carried out in the mill. In other embodiments, any suitable apparatus can be used.

[0030] In some embodiments, at 106 the starting material is combined with water to yield a slurry or mixture. In some embodiments, the level of solids present in the slurry is between about 5% and about 50% by weight, including between about 10% and about 30% by weight, including any value or subrange therebetween, e.g. about 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, 32, 34, 36, 38, 40, 42, 44, 46, or 48% by weight. In some embodiments, the level of solids present in the mixture is approximately 20% by weight.

[0031] In some embodiments at 104, size reduction of the starting material is carried out to activate alkali metals in the starting material. In some embodiments, the mixture is combined with a suitable media such as mild steel ball media, stainless steel media, alumina media, ceramic media, tungsten carbide media, zirconia media, zirconia toughened alumina media, or the like at step 104 and grinding is carried out for a treatment period. In one example embodiment, approximately 10 kg of mild steel ball media is added per kg of starting material and a mild steel grinding mill is used to carry out size reduction step 106. In other embodiments, size reduction can be carried out in any suitable manner. In some embodiments, size reduction is carried out in a mill having a stainless steel liner, which without being bound by theory may assist in reducing formation of iron oxide during size reduction. In some embodiments, size reduction step 104 is carried out at atmospheric (i.e. ambient) pressure.

[0032] In some embodiments, the size reduction step 104 is carried out for a treatment period of between about 15 minutes and about 12 hours, including between about 30 minutes and about 12 hours, including between about 2 hours and about 10 hours, including any value or subrange therebetween, e.g. about 15, 20, 25, 30, 35, 40, 45, 50 or 55 minutes or 1 , 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11 or 11 .5 hours. In some embodiments by way of example only, the size reduction step 104 is carried out for a treatment period of approximately 4 hours. The duration of the treatment period can be adjusted by one skilled in the art based on the input size of the starting material and the grinding intensity applied to the starting material. For example, grinding under higher pressure in a stirred mill may require less processing time than grinding in a ball mill at atmospheric pressure.

[0033] In some embodiments, the size reduction step 104 is carried out at ambient temperature. In some embodiments, the size reduction step 104 is carried out at a temperature in the range of about 10°C to about 80°C, including any temperature or subrange therebetween, e.g. 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70 or 75°C. In some embodiments, the only heat supplied at size reduction step 104 is the friction heat generated by the size reduction of the starting material.

[0034] In some embodiments, the size reduction step 104 is carried out until the starting material reaches a desired size profile. In one example embodiment in which the starting material is glass, the glass is ground to have a D50 passing in the range of about 2 to about 15 pm, including any value or subrange therebetween, e.g. about 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14 or 15 pm, and including between about 5 to about 15 pm.

[0035] It is noted that ASTM C1886 / C1886M requires that a minimum of 95% of glass powder to be incorporated into concrete passes a 325-mesh wet sieve. In some embodiments, the glass is ground to a sufficient extent to be compliant with this or any other applicable requirement.

[0036] After the size reduction step 104 has been completed, the resultant mixture is dewatered in any suitable manner at step 108 to remove the activated alkali metal rich solution from the treated starting material. For example, the treated material could be filtered through a sieve of appropriate mesh or liquid suctioned off to yield the desired end product pozzolan at 114. In some embodiments, centrifuging could be used to precipitateor sediment the desired solids and allow for removal of the liquid supernatant, a hydrocyclone could be used, a thickener settling tank could be used, and / or fine-mesh pressure filtering could be carried out, or the like, to separate the desired pozzolan 114 from the alkali metal rich solution 110.

[0037] In some embodiments, a CC>2-solubilizer is added at 112 or at 104 or 106. In some embodiments, the CC>2-solubilizer is glycerin (propane-1 ,2 , 3-triol) . In some embodiments, the CC>2-solubilizer is added to the mixture at a rate of about 6 g per kg of starting material. Without being bound by theory, it is believed that glycerin may act to enhance the solubility of carbon dioxide in aqueous solution and may allow for the formation of a greater carbonic acid (H2CO3) concentration for conducting the desired acid-base reaction to sequester carbon and remove alkali metal salts. In some embodiments, the CC>2-solubilizer is omitted.

[0038] In some embodiments, other additives are added at 112 or at 104 or 106. In some embodiments, TiC>2 is added at 112 or 104 or 106, which without being bound by theory may assist in carbonating NaOH. In some embodiments, the TiC>2 is added to the mixture at a ratio of about 1 % by weight of dry matter (i.e. at a rate of about 1 % by weight of the starting material). In some embodiments, the other additive such as TiC>2 is omitted.

[0039] In some embodiments, at 112, a gas such as carbon dioxide is supplied. In some embodiments, the gas contains carbon dioxide at a concentration in a range of between about 5% and about 100%, including any value therebetween, e.g. 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65 70, 75, 80, 85, 90 or 95%. In some embodiments, the gas includes other gases, for example flue gases that are unprocessed or only partially processed, and which may contain other oxidizing gases such as CO, SO2, SO3, NO, NO2, NO3, H2O, and the like. In some embodiments, the pressure of the pressurized gas that is added to the reaction mixture is in the range of about 5 to about 150 psi gauge, including between about 20 to about 100 psi gauge, including any value or subrange therebetween, e.g. 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140 or 145 psi gauge. In some embodiments, step 112 is conducted at atmospheric (i.e. ambient) pressure. The pressure at which the gas containing carbon dioxide is supplied could be adjusted by the person skilled in the art to remain within the maximum pressure limits of the apparatus being used to conduct the process, while still being high enough to dissolve a sufficient amount of carbon dioxide to yield a desired amount of carbonic acid to chemically activate alkali metals in the starting material.

[0040] In some embodiments, the gas containing carbon dioxide is supplied to the alkali metal rich solution at 112 in any suitable contactor vessel, e.g. a sparger, a diffuser, a contactor tower, or the like. In some embodiments, the contactor tower is run with gas and solution in parallel or co-current flow. In some embodiments, the contactor tower is run with the gas and solution in counter or counter-current flow.

[0041] In some embodiments, step 112 is carried out at ambient temperature. In some embodiments, step 112 is carried out at a temperature in the range of about 10°C to about 80°C, including any temperature or subrange therebetween, e.g. 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70 or 75°C. In some embodiments, step 112 is carried out for a treatment period of between about 15 minutes and about 12 hours, including between about 30 minutes and about 12 hours, including between about 2 hours and about 10 hours, including any value or subrange therebetween, e.g. about 15, 20, 25, 30, 35, 40, 45, 50 or 55 minutes or about 1 , 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11 or 11.5 hours.

[0042] In some embodiments, release of pressure and repressurization is carried out at step 112 to vent off gases such as nitrogen and / or oxygen, and / or to introduce additional carbon dioxide gas, as carbon dioxide gas is consumed in the course of reactions to form sodium, calcium and magnesium carbonates and the like. In some embodiments in which the pressurized gas that is used contains a high partial pressure of carbon dioxide, it is not necessary to carry out such a step of pressure reduction and re-introduction of pressurized gas.

[0043] In some embodiments, at step 116, the resultant pozzolan product obtained at step 114 is dried in any suitable manner. In some embodiments, drying is conducted e.g. at a temperature in the range of about 100°C to about 600°C, including any value or subrange therebetween e.g. 150, 200, 250, 300, 350, 400, 450, 500, 550, or 600°C after pressure filtration for a suitable drying period, e.g. overnight (i.e. at least eight hours). The person skilled in the art could adjust the drying conditions to be suitable for any particular material and desired level of dryness. For example, the temperature at which the drying is conducted may vary depending on the ambient air moisture level, the remaining moisture content in the processed material after dewatering, drying volume capacity, and so on. The drying conditions can be selected to dry the treated material to any desired level, e.g. torender the treated pozzolan material compliant with ASTM C1866 requirements (0.5% maximum moisture content), or any other applicable standard.

[0044] In some embodiments, after the product is dried, size homogenization may be conducted at 118 to return the finished product to the same size range as was achieved prior to dewatering (i.e. for glass in one example embodiment a D50 passing in the range of about 2 to about 15 pm, including any value or subrange therebetween, e.g. about 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14 or 15 pm, and including between about 5 and about 15 pm). Without being bound, in some aspects agglomeration may occur as the product is dewatered and dried and so this additional size homogenization or grinding step can be carried out in any suitable manner to return the final product to the desired size for subsequent use, e.g. in cement and ultimately concrete. For example, in some embodiments, size homogenization is carried out via a short period of ball milling at step 118.

[0045] In some embodiments, subsequent to size homogenization, at step 120 a quality control step is carried out to ensure particles outside of a desired size range are removed from the pozzolan powder product. In some embodiments, the quality control step is conducted by air classification to remove undesirably large particles from the pozzolan powder product.

[0046] With reference to FIG. 2, a second example embodiment of a process 200 for producing a pozzolan from a starting material is illustrated. Process 200 is generally similar to process 100 except that the starting material is size reduced prior to forming an aqueous slurry. At 202, a starting material is supplied and at 204 the starting material is size reduced to the desired size range to activate alkali metals in the starting material. In some embodiments if desired any suitable grinding aid can be added at 2O4.ln some embodiments, the starting material is ground to the desired size range in a dry ball mill, stirred mill, or in any other suitable apparatus. In one example embodiment in which the starting material is glass, the glass is ground to have a D50 passing in the range of about 2 to about 15 pm, including any value or subrange therebetween, e.g. about 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14 or 15 pm, including between about 5 and about 15 pm. Any of the starting materials described for method 100 could be treated by method 200.

[0047] It is noted that ASTM C1886 / C1886M requires that a minimum of 95% of glass powder to be incorporated into concrete passes a 325-mesh wet sieve. In some embodiments, the glass is ground to a sufficient extent to be compliant with this or any other applicable requirement.

[0048] At 206, the size-reduced starting material is combined with water to form a slurry or mixture. In some embodiments, the amount of water added at 206 is sufficient so that the level of solids present in the mixture is between about 5% and about 50% by weight, including between about 10% and about 30% by weight, including any value or subrange therebetween, e.g. about 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, 32, 34, 36, 38, 40, 42, 44, 46, or 48% by weight. In some embodiments, the level of solids present in the mixture is approximately 20% by weight. In some embodiments, step 206 is conducted in a ball mill with no media. In some embodiments, the ball mill is a wet ball mill (e.g. rubber lined with standard lifters to agitate the mixture). In some embodiments, step 206 is conducted in a stirred tank, agitation tank, attrition scrubber tank, or by pumping through an inline mixer. In other embodiments, any suitable apparatus may be used.

[0049] In some embodiments, a CO2-solubilizer is added at 206 or at 212. In some embodiments, the CO2-solubilizer is glycerin (propane-1 ,2 , 3-triol) . In some embodiments in which the CC>2-solubilizer is glycerin, the CC>2-solubilizer is added to the mixture at a rate of about 6 g per kg of starting material. In some embodiments, other additives are added at 206. In some embodiments, TiC>2 is added at 206 or at 212, which without being bound by theory may assist in carbonating NaOH. In some embodiments, the TiC>2 is added to the mixture at a ratio of about 1 % by weight of the dry matter in the mixture. In some embodiments, the CO2-solubilizer and / or other additive is omitted.

[0050] In some embodiments, the slurry formed at step 206 is mixed, stirred or otherwise agitated for a treatment period sufficient to allow alkali metals present in the starting material to be activated for removal by the aqueous solution. In some embodiments, the treatment period at step 206 is at least 10 to at least 120 minutes, including any value or subrange therebetween, e.g. 15, 20, 25, 30, 40, 50, 60, 80, 100 minutes, or any suitable time interval. In some embodiments, the temperature at which step 206 is carried out is a temperature in the range of about 10°C to about 80°C, including any temperature or subrange therebetween, e.g. 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70 or 75°C.

[0051] After processing step 206 is completed, the mixture is dewatered at 208 in any appropriate manner to remove the activated alkali metals from the treated starting material with the water as an alkali metal rich solution at 210 and the treated pozzolan product at 214. For example, the material could be filtered through a sieve of appropriate mesh or liquid suctioned off to yield the desired end product. In some embodiments, centrifuging could be used to precipitate the desired solids and allow for removal of the liquid supernatant, a hydrocyclone could be used, a thickener settling tank could be used, and / or fine-mesh pressure filtering could be carried out, or the like.

[0052] At 212, CO2 or other gas is supplied to the alkali metal rich solution in any suitable contactor vessel, e.g. a sparger, diffuser, a contactor tower, or the like. In some embodiments, the contactor tower is run with gas and solution in parallel or co-current flow. In some embodiments, the contactor tower is run with the gas and solution in counter or counter-current flow. In some embodiments, the carbon dioxide could be in combination with other gases, for example flue gases that are unprocessed or only partially processed, and which may contain other oxidizing gases such as CO, SO2, SO3, NO, NO2, NO3, H2O, and the like. In some embodiments, the pressure of the pressurized gas that is added to the reaction mixture is in the range of about 5 to about 150 psi gauge, including between about 20 to about 100 psi gauge, including any value or subrange therebetween, e.g. 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140 or 145 psi gauge. In some embodiments, step 212 is conducted at atmospheric (i.e. ambient) pressure. The pressure at which the carbon dioxide is supplied could be adjusted by the person skilled in the art to remain within the maximum pressure limits of the apparatus being used to conduct the process, while still being high enough to dissolve a sufficient amount of carbon dioxide to yield a desired reaction profile.

[0053] At 212, the alkali metal rich solution is processed with the gas to facilitate dissolution of carbon dioxide to form carbonic acid, which reacts with alkali metals present in solution to both react with the alkali metals and sequester carbon. In some embodiments, step 212 is carried out for a treatment period of between about 15 minutes and about 12 hours, including between about 30 minutes and about 12 hours, including between about 2 hours and about 10 hours, including any value or subrange therebetween, e.g. about 15, 20, 25, 30, 35, 40, 45, 50 or 55 minutes or about 1 , 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11 or 11.5 hours.

[0054] In some embodiments, after an initial addition of pressurized gas at 212, pressure release and repressurization is carried out to vent off gases and / or to introduce additional gases. This release of pressure and re-introduction of pressurized gas can be done at any time during step 212. In some embodiments, these release and repressurization steps are carried out to vent off gases such as nitrogen and / or oxygen, and / or to introduce additional carbon dioxide gas, as carbon dioxide gas is consumed in the course of reactions to form sodium and calcium carbonates and the like. In some embodiments in which the pressurized gas that is used contains a high partial pressure of carbon dioxide, it is not necessary to carry out such a step of pressure reduction and re-introduction of pressurized gas.

[0055] In some embodiments, step 212 is carried out at ambient temperature. In some embodiments, step 212 is carried out at a temperature in the range of about 10°C to about 80°C, including any temperature or subrange therebetween, e.g. 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70 or 75°C.

[0056] In some embodiments, prior to carbon dioxide being supplied to the aqueous solution as 212, the aqueous solution is concentrated at 215, for example using a membrane or distillation unit. Concentration step 215 increases the concentration of alkali hydroxide, e.g. NaOH, present in the aqueous solution prior to exposure to carbon dioxide.

[0057] In some embodiments, at step 216, the pozzolan product from step 214 is dried in any suitable manner. In some embodiments, drying is conducted e.g. at a temperature in the range of about 100°C to about 600°C, including any value or subrange therebetween e.g. 150, 200, 250, 300, 350, 400, 450, 500, 550, or 600°C after dewatering for a suitable drying period, e.g. overnight. The person skilled in the art could adjust the drying conditions to be suitable for any particular material and desired level of dryness. For example, the temperature at which the drying is conducted may vary depending on the ambient air moisture level, the remaining moisture content in the processed material after dewatering, drying volume capacity, and so on. The drying conditions can be selected to dry the treated material to any desired level, e.g. to render the treated pozzolan material compliant with ASTM C1866 requirements (0.5% maximum moisture content), or any other applicable standard.

[0058] In some embodiments, after the product is dried, size homogenization may be conducted at 218 to return the finished product to the same size range as was achieved prior to forming the aqueous slurry (i.e. for glass in one example embodiment a D50 passing in the range of about 2 to about 15 pm, including any value or subrange therebetween, e.g. about 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14 or 15 pm, and including between about 5 and about 15 pm). Without being bound, in some aspects agglomeration may occur as the pozzolan product is dewatered and dried and so this additional size homogenization or grinding step can be carried out in any suitable manner to return the final product to the desired size for subsequent use, e.g. in cement and ultimately concrete. For example, in some embodiments, size homogenization is carried out via a short period of ball milling.

[0059] In some embodiments, subsequent to size homogenization, at step 220 a quality control step is carried out to ensure particles outside of a desired size range are removed from the pozzolan powder product. In some embodiments, the quality control step is conducted by air classification to remove undesirably large particles from the pozzolan powder product.

[0060] In some embodiments, the alkali metal that is activated and removed from the starting material by the removal of an alkali metal rich solution through method 100 or 200 is sodium. In some embodiments, the amount of alkali metal in the form of sodium that is removed from glass as a starting material is in the range of about 5% to about 25%, including any value therebetween, e.g. 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 , 22, 23 or 24%. In some embodiments, a process is provided for producing a ground glass pozzolan from a glass starting material, wherein the amount of sodium removed from the glass starting material to produce the ground glass pozzolan is in the range of about 5% to about 25%, including any value therebetween, e.g. 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 , 22, 23 or 24%.

[0061] In some embodiments, the treated pozzolan is crushed glass having a D50 passing in the range of about 2 to about 15 pm, including any value therebetween, e.g. 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13 or 14 pm. In some embodiments, the treated pozzolan is glass that has a carbon content of at least approximately 0.5% by weight, including e.g. at least approximately 0.4% or at least approximately 0.6%. In some embodiments, the treated pozzolan is glass that has a sodium content of between about 7.2% and 9.0%, includingany value or subrange therebetween, e.g. 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1 , 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8 or 8.9%.

[0062] In some embodiments, the treated pozzolan is used as a component of a cement mixture. For example, the treated pozzolan may be mixed with Portland cement to form a cement mixture. In some embodiments, the treated pozzolan is incorporated into cement at a rate of about 5% to about 70% w / w, including between 20% to 30% w / w, and including any value or subrange therebetween e.g. 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, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66 or 68% w / w. In some embodiments, the cement is incorporated into concrete at a ratio of approximately 15% w / w on a dry matter basis (e.g. about 10-20% w / w, including any value or subrange therebetween e.g. about 11 , 12, 13, 14, 15, 16, 17, 18 or 19% w / w). In some embodiments, the treated pozzolan is incorporated into concrete in an amount of between about 1 % to about 12%, including any value or subrange therebetween, e.g. about 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11 %.

[0063] With reference to FIG. 3, in some embodiments the pH of the reaction mixture is used to determine the duration of the treatment period. More specifically, in an example embodiment of a method 300 for producing a treated pozzolan, changes in pH of the reaction mixture are used to determine the treatment period for the reaction mixture. Method 300 is generally similar to method 200, and equivalent steps are described with reference numerals incremented by 100 and are not further described again in detail. Method 300 could also be applied to method 100 using the basic steps of method 100 and adding step 313 thereto, and the corresponding steps of method 300 have been incremented by 200 relative to the steps described for method 100.

[0064] In method 300, a starting material is provided at 302. In some embodiments, the starting material is post-consumer glass. Any of the starting materials described with reference to method 100 can be used in method 300. At step 304, the starting material is size reduced to a desired particle size to activate alkali metals in the starting material, and at 306 an aqueous slurry is formed and then dewatered at step 308. In some embodiments if desired any suitable grinding aid can be added at 304. At step 312, optionally after concentration step 315, an atmospheric or pressurized source of carbon dioxide is provided, so that carbon dioxide gas is introduced into the aqueous slurry. At step 312, the reaction mixture is processed to allow the carbon dioxide to dissolve into the aqueous solution toform carbonic acid, which reacts with alkali metals present in the aqueous solution to sequester carbon.

[0065] In some embodiments the starting material is not size reduced prior to forming an aqueous slurry at step 306, but rather the starting material is size reduced simultaneously with forming an aqueous slurry at step 306, as described with reference to method 100.

[0066] Prior to the introduction of carbon dioxide, in embodiments in which the starting material is glass, e.g. post-consumer glass, the aqueous slurry at step 306 has a strongly alkaline pH, e.g. in the range of about 10.5-12.5, including any value therebetween e.g. 11.0, 11.5, or 12.0.

[0067] The aqueous slurry is dewatered at 308 to release the activated alkali metals from the starting material with the water as an alkali metal rich solution 310, and a pozzolan product at 314. The pozzolan product is dried at 316, and optionally size reduced at 318 to homogenize the size of the particles present, and / or optionally subject to a quality control step to ensure the presence of only particles having a desired size range at 320 as described for methods 100 and 200.

[0068] As carbon dioxide is introduced into the alkali solution at 312, optionally after concentration at step 315, the carbon dioxide dissolves in the water and forms carbonic acid (H2CO3). As the concentration of carbonic acid in the aqueous slurry increases, the pH of the aqueous slurry will correspondingly decrease. In some embodiments, the addition of gas containing carbon dioxide continues at step 312 until the pH of the aqueous slurry reaches a predetermined low level of between about 4.0 and about 6.0, including any value therebetween (e.g. 4.5, 5.0 or 5.5). Once the pH reaches the predetermined low level, carbon dioxide introduction is stopped and processing step 312 is permitted to continue for a treatment period at 313. In some embodiments, the treatment period is between about 0.25 hours and about 12 hours, including any value or subrange therebetween, e.g. about 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 060, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1 , 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11 , or 11.5 hours.

[0069] After the introduction of pressurized gas containing carbon dioxide is stopped, the pH of the aqueous slurry will gradually increase as the carbonic acid reacts with alkali metal oxides in solution for a second period. In some embodiments, processing step 313 is halted after the pH of the aqueous slurry increases to a predetermined high level of about 6.0 toabout 7.0, including any value therebetween, e.g. about 6.1 , 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, or 6.9.

[0070] In some embodiments, after the pH of the aqueous slurry increases to the predetermined high level at step 313, step 312 is repeated and additional gas containing carbon dioxide is again introduced to the aqueous slurry, and processing step 313 is again repeated. For example, if the pH returns to a high level of about 11 , this suggests that hydroxides still remain in solution and available for further reaction with carbonic acid, so that additional carbon dioxide should be added. Or if there is a substantial drop in pressure after additional pressurized gas containing carbon dioxide is added in embodiments where the gas containing carbon dioxide is supplied above atmospheric pressure, this suggests that carbon dioxide continues to dissolve into the reaction mixture. Generally speaking, an excess amount of carbon dioxide is added relative to the level of sodium, calcium and magnesium ions present in the reaction mixture. Any excess carbon dioxide added to the process that does not dissolve into solution may be recaptured for use in further processing of additional starting material.

[0071] With reference to FIG. 4, an example embodiment of an apparatus 400 for processing a starting material to produce a treated pozzolan is illustrated. Apparatus 400 is suitable for use in methods 100, 200 or 300, for example. Apparatus 400 includes a size reduction apparatus 402 such as a stirred- bead vertical mill (e.g. a VertiMill or HIGmill), horizontal mill (e.g. an IsaMill), vibratory mill (e.g. VKE Mill), dry ball mill, stirred mill, roller mill, or the like. Optionally the starting material can be combined with water in size reduction apparatus 402 to form an aqueous slurry, or optionally the size reduced starting material can be passed to a mixing apparatus 403 to be combined with water to form the aqueous slurry. In some embodiments, mixing apparatus 403 may be a stirred tank, agitation tank, attrition scrubber tank, inline mixer, or the like.

[0072] A dewatering apparatus 414 is provided for receiving the aqueous slurry. Dewatering apparatus 414 can be used to dewater the aqueous slurry to produce an alkali metal rich solution for contactor vessel 404 and a dewatered pozzolan product. In some embodiments, the dewatering apparatus is a filtration unit, a centrifuge, a sedimentation tank, a hydrocyclone, or a thickener settling tank or the like.

[0073] Apparatus 400 further includes a contactor vessel 404, which is suitable for receiving gas containing carbon dioxide while processing the alkali metal rich aqueous solution separated from the aqueous slurry of treated starting material. In some embodiments, the contactor vessel is a sparger, a diffuser, a contactor tower, or the like. In the illustrated embodiment, a pump 406 is provided to pump carbon dioxide containing gas from a carbon dioxide tank 408 into contactor vessel 404. In some embodiments, including the illustrated embodiment, carbon dioxide containing gas from the headspace above the aqueous slurry of starting material in contactor vessel 404 is recycled to carbon dioxide tank 408 via pump 406 and re-used in the process.

[0074] In some embodiments, including the illustrated embodiment, a pressure sensor 410 and / or a pH meter 412 are provided, so that the pressure and / or pH inside of contactor tower 404 can be monitored.

[0075] In some embodiments, a concentrator 415 is provided to concentrate the alkali metal rich solution obtained from dewatering apparatus 414 prior to supplying the solution to contactor vessel 404. Concentrator 415 may be any suitable concentration apparatus in various embodiments, for example a membrane, a distillation unit, or the like.

[0076] From dewatering apparatus 414, the dewatered pozzolan product is passed to any suitable drying apparatus such as an air dryer 416. Air dryer 416 can be used to dry the pozzolan product, and a size reduction apparatus such as a ball mill, rolls crusher, pulverizer or the like illustrated as 418 can be provided to carry out an additional size reduction step of the treated pozzolan material to help provide a homogenous particle size in the finished product. In some embodiments an apparatus such as an air classifier 420 can be provided to remove undesirably large particles from the treated pozzolan material.

[0077] In some embodiments, for example those used to carry out method 500 or method 600, an acid washing and rinsing apparatus 430 is optionally provided after dewatering apparatus 414 but prior to air dryer 416. Any suitable apparatus can be used for acid washing and rinsing apparatus 430 that allows fresh water to be introduced to wash the pozzolan product, for example a filtration unit, a centrifuge, a sedimentation tank, a hydrocyclone, or a thickener settling tank or the like.

[0078] In some embodiments, as illustrated in more detail with reference to method 500 in FIG. 5, the dewatered pozzolan product obtained at steps 114, 214 or 314 can be subjectedto an acid rinse step 530 and optionally a further water rinse step 532 prior to being passed to drying step 116, 216 or 316. Method 500 is generally similar to method 100, and equivalent steps are described with reference numerals incremented by 400 and are not further described again in detail. Method 500 could also be applied to method 200 or method 300 using the basic steps of method 200 or 300 and adding steps 530 and 532 thereto, and the corresponding steps of method 500 have been incremented by 300 relative to the steps described for method 200 and by 200 relative to the steps described for method 300. Such steps include providing starting material at 502, adding water at 506, size reduction at 504, dewatering at 508, obtaining an alkali solution after dewatering at 510, optionally concentrating the alkali solution at 515, and providing carbon dioxide to the alkali solution at 512.

[0079] In some embodiments, after the pozzolan product is dewatered at 508 and obtained at 514, the dewatered pozzolan product is subjected to an acid rinse at 530. Without being bound by theory, rinsing the dewatered pozzolan product with an acid may assist in removing additional alkali metals such as sodium from the glass by reacting with alkali metal on the surface of the glass to further enhance removal of the alkali metal from the glass. Any suitable acid can be used at acid rinse step 530. In some embodiments, a strong acid (i.e. an acid that dissociates completely or nearly completely in water) such as hydrochloric acid, nitric acid, sulfuric acid, hydrobromic acid, hydroiodic acid, chloric acid, perchloric acid or the like is used at acid rinse step 530. In some embodiments, a weak acid (i.e. an acid that does not dissociate completely in water) is used at acid rinse step 530, including by way of example only acetic acid, formic acid, nitrous acid, sulfurous acid, or the like. In some embodiments, the acid is hydrochloric acid.

[0080] In some embodiments, the acid is provided at a concentration of about 2 M to about 18 M (including any value or subrange therebetween, e.g. 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0 or 17.0 M) at acid rinse step 530. In some embodiments, the acid is added at acid rinse step 530 at a concentration in the range of between about 33% to about 95% by weight, including any value or subrange therebetween e.g. 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85 or 90% by weight. The person skilled in the art would be able to select an appropriate acid and concentration to achieve the desired removal of alkali metals from the glass while avoiding the production of corrosive or otherwise hazardous conditions that would be undesirable to implement.

[0081] In some embodiments, acid rinse step 530 is carried out for any desired time period, for example between about 0.5 hours to about 2 hours, including any value or subrange therebetween e.g. about 45 minutes, about 1 hour, or about 1.25, 1.50 or 1.75 hours. In some embodiments, acid rinse step 530 is carried out at ambient temperature and at ambient pressure.

[0082] In some embodiments, as illustrated in FIG. 5, after acid rinse step 530, the pozzolan product is rinsed at 532, for example by dewatering, rinsing with water, and dewatering again, to remove any residual acid and alkali metal ions from the pozzolan product. In some embodiments, the pozzolan product is rinsed multiple times at 532, for example by carrying out two, three or more rinse cycles at 532. In some embodiments, each rinse cycle is conducted for a period of between about 0.5 hours to about 2 hours, including any value or subrange therebetween e.g. about 45 minutes, about 1 hour, or about 1.25, 1.50 or 1.75 hours, prior to removal of liquid by dewatering and addition of fresh water to carry out the subsequent rinse cycle. After rinse step 532 if used or after acid rinse step 530 if rinse step 532 is not used, the resulting pozzolan product is dried at 516, subjected to a further round of size reduction at 518 and subjected to a quality or size control at 520 as previously described.

[0083] As illustrated with reference to method 600 in FIG. 6, in some embodiments an improved pozzolan product is obtained without sequestering carbon dioxide in the process. Method 600 is generally similar to method 500, and corresponding steps of method 600 have been incremented by 100 and are not further described again herein including providing starting material at 602, adding water at 606, size reduction at 604, dewatering at 608, obtaining the dewatered pozzolan at 614, carrying out acid rinse step 630 and optionally rinse step 632, drying the resulting pozzolan product at 616, size reduction at 618 and quality or size control at 620 as previously described

[0084] Method 600 differs from method 500 in that the steps of obtaining an alkali solution after dewatering at 510, optionally concentrating the alkali solution at 515, and providing carbon dioxide to the alkali solution at 512 are omitted. Thus, method 600 can be used to produce a treated pozzolan product having improved properties without the additional benefit of sequestering carbon dioxide.Examples

[0085] Further embodiments are described with reference to the following examples, which are intended to be illustrative and not limiting in nature.Example 1 - Enhanced Strength of Concrete Made with Treated Glass Pozzolan

[0086] To evaluate the efficacy of removal of sodium from ground glass pozzolan in mitigating the effects of alkali-silica reactivity, a ground glass sample (1.00 kg) was screened to pass 850 urn and added to deionized water (935 mL) and ground down for 26.5 minutes achieving a pH of 11.6 in a batched stirred mill. The stirred mill had media changed out from 3 - 5 mm ceramic beads to 1 .7 - 2.0 mm ceramic beads and attached to a recirculating feed tank. Deionized water (1 .428 L) was added to the feed tank before running the stirred mill and pump for the recirculating feed tank. Excess HCI (0.865 L, 20%) was added to bring the pH of the solution down to 0.6 to effect acid removal of sodium ions from the treated glass. The stirred mill with recirculating feed tank was run for 2 hours before a subsample was extracted for solid and solution assays. The stirred mill with recirculating feed tank was run for an additional hour, 3 hours total, before a second subsample was extracted for solid and solution assays. After 3 hours of mixing, the pH of the solution was 0.41 and the particle size distribution was 2.2 pm K50. The sample was allowed to sit in the acidic solution overnight (14 hours) and rose to a pH of 1.45 before a final solid and solution sample was collected for assays. The remaining slurry was pressure filtered and rinsed with deionized water before being incorporated into concrete and tested for alkali-silica reactivity (ASTM C1567) and strength activity index (ASTM C311).

[0087] Tables 1 and 2 show the efficacy of the acid treatment in removing sodium ions from the treated ground glass pozzolan: the amount of sodium removed increased with a longer treatment period (Table 1), and after the overnight soak following grinding of the glass starting material in aqueous solution, 20.7% of the sodium in the glass starting material had been removed (Table 2).

[0088] As can be seen from Tables 3 and 4, the treated ground glass pozzolan when incorporated into concrete exhibited both greater strength than an untreated ground glass pozzolan (113.4% of the strength of the control concrete made from Portland cement versus 83% for the untreated ground glass pozzolan, Table 3), and lower alkali silica reactivity(0.05% expansion in ASR testing versus 0.16 for untreated ground glass pozzolan, Table4). Thus, this example demonstrates that removal of alkali metal ions, namely sodium, from the ground glass pozzolan is associated with both decreased alkali silica reactivity and enhanced strength of the concrete end product.Table 1. Removal of sodium from glass starting material.Table 2. Calculation of sodium removed from glass starting material.Table 3. Evaluation of strength of concrete made using treated vs. untreated ground glass pozzolan.Table 4. Evaluation of alkali-silica reactivity of concrete made using treated vs. untreated ground glass pozzolan.Example 2 - Reduced Expansion of Concrete Made Using Treated Ground Glass Pozzolan

[0089] To evaluate the characteristics of concrete produced using the treated glass as a proof of concept, ASTM-C1567 testing was carried out on a sample produced from an early iteration of the described process. This test showed that the treated sample shows less expansion (0.11 % at 14 days) than the original glass sample (0.16% at 14 days). Briefly, ASTM-C1567 testing involves mortar bars (25 x 25 x 285 mm) being produced with the aggregate of interest. The bars are stripped from their forms after 24 hours moist curing. The 1 -day-old bars are then placed in water in a sealed plastic container at room temperature. The containers (and bars) are placed in an oven at 80°C and remain there for 24 hours. The 2-day-old bars are removed from the water and are placed in a lengthchange comparator to establish the initial (reference) length. The bars are then placed in sealed plastic containers containing 1 molar sodium hydroxide solution - the solution having been preheated to 80°C. The bars are removed from the containers periodically and placed in the length comparator to determine the length change from the reference reading. The length change after 14 days in NaOH (bars are now 16 days old) is usually used as the performance indicator.Example 3 - Strength Activity and Water Demand of Treated Wet Ground Glass Pozzolan

[0090] An example method was conducted using glass that was previously ground in a 3 ft diameter ball mill and screened for +300 pm material with an input size of 80 - 100 pm d50.The experiment was conducted using a vertical stirred mill equipped with a mild steel rotor and 1.5 - 3.0 mm diameter ceramic beads. Glass (325 g) was loaded into the mill canister along with water (1 ,300 g), grinding media (2,400 g), and the rotor. The mill canister was sealed and the drive motor turned on and adjusted to 1 ,500 rpm. The drive motor was allowed to run until the desired particle size (3, 6, and 9 pm d50) was obtained where it was stopped and the sizing verified by a laser diffraction particle size analyzer. The mill canister was opened and the rotor removed before the contents were dumped onto a bead removal screen (1 mm) and a secondary screen (63 pm). The screened slurry was pressure filtered and the liquid filtrate collected for analysis and the solid filter cake processed for analysis and concrete testing. Results for a preliminary experiment for sodium extraction, water demand and strength activity index (SAI) are presented in Table 5 below, and results for a second experiment are shown in Table 6 below. Water demand and SAI were determined according to ASTM C311 / C311 M. Table 5. Exemplary removal of sodium and determination of water demand and strength activity index for ground glass pozzolan produced according to an exemplary embodiment.Table 6. Exemplary removal of sodium and determination of water demand and strength activity index for ground glass pozzolan produced according to an exemplary embodiment.Example 4 - Comparative Example - Strength Activity and Water Demand of Dry Ground Glass Pozzolan

[0091] An example method was conducted using glass that was previously ground in a 3 ft diameter ball mill and screened for +300 pm material with an input size of 80 - 100 pm d50 using dry grinding only, i.e. without addition of water to form an alkali metal rich solution. The experiment was conducted using a vertical stirred mill equipped with a mild steel rotor and 1.5 - 3.0 mm diameter ceramic beads. Glass (325 g) was loaded into the mill canister along with grinding media (2,000 g) and the rotor. The mill canister was sealed and the drive motor turned on and adjusted to 1 ,200 rpm. The drive motor was allowed to run until the desired particle size (4, 6, and 9 pm d50) was obtained where it was stopped and the sizing verified by a laser diffraction particle size analyzer. The mill canister was opened and the rotor removed before the contents were dumped onto a bead removal screen (1 mm). The powdered glass was collected for analysis and concrete testing. Results for sodium extraction, water demand and strength activity index (SAI) are from a preliminary experiment are presented in Table 7 below, and results for a second experiment are shown in Table 8 below. Water demand and SAI were determined according to ASTM C311 / C311M.

[0092] In addition to the results shown in Tables 7 and 8, samples having a D50 of 27 pm and 15 pm were also tested and had a strength activity index (SAI) after 7 days of 74.6% and 77.8%, respectively.Table 7. Exemplary change in sodium and determination of water demand and strength activity index for dry ground glass pozzolan treated according to a comparative process.Table 8. Exemplary change in sodium and determination of water demand and strength activity index for dry ground glass pozzolan treated according to a comparative process.

[0093] The foregoing results demonstrate that treatment of the glass in an aqueous slurry as described herein and removal of the alkali metal rich solution from the treated glass enhances the utility and / or properties of the ground glass as a pozzolan.

[0094] While a number of exemplary aspects and embodiments have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are consistent with the broadest interpretation of the specification as a whole.

Claims

CLAIMS:1 . A process for producing a pozzolan from a starting material, comprising the steps of: size-reducing the starting material; forming an aqueous slurry containing the starting material; mixing the aqueous slurry to yield a solid treated pozzolan and an aqueous solution containing alkali metals; and separating the solid treated pozzolan and the aqueous solution containing alkali metals.

2. The process as defined in claim 1 , further comprising supplying a gas containing carbon dioxide to the aqueous solution containing alkali metals for a treatment period to sequester the carbon dioxide.

3. The process as defined in either one of claims 1 or 2, wherein the step of sizereducing the starting material is conducted prior to forming the aqueous slurry, wherein optionally the size reduction step is conducted in a vertical mill.

4. The process as defined in any one of claims 1 to 3, wherein the step of size-reducing the starting material is conducted after forming the aqueous slurry, optionally wherein the mixing of the aqueous slurry is carried out in a tumbling ball mill, a stirred bead mill, a horizontal mill, a vibratory kinetic mill, or a roller mill.

5. The process as defined in any one of claims 1 to 4, wherein the step of separating the solid treated pozzolan from the aqueous solution containing the alkali metals comprises filtration, sedimentation, use of a hydrocyclone, and / or use of a thickener settling tank.

6. The process as defined in any one of claims 1 to 5, comprising drying the solid treated pozzolan.

7. The process as defined in claim 6, wherein drying the solid treated pozzolan comprises drying at ambient temperature for a period of at least eight hours.

8. The process as defined in either one of claims 6 or 7, further comprising a second size reduction step conducted subsequent to the step of drying the solid treatedpozzolan, wherein optionally the second size reduction step is conducted using a ball mill, rolls crusher or pulverizer.

9. The process as defined in any one of claims 6 to 8, further comprising a step of removing undesirably large particles after the step of drying the solid treated pozzolan or after the second size reduction step, wherein the step of removing undesirably large particles optionally comprises air classification.

10. The process as defined in any one of claims 1 to 9, wherein the gas containing carbon dioxide comprises carbon dioxide and one or more of CO, SO2, SO3, NO, NO2 and / or NO3.11 . The process as defined in any one of claims 1 to 10, wherein the starting material comprises soda-lime glass.

12. The process as defined in any one of claims 1 to 10, wherein the starting material comprises post-consumer glass waste, E-glass, flat glass or plate glass.

13. The process as defined in claim 12, wherein: the post-consumer glass waste comprises glass bottles and / or glass jars, optionally wherein the glass jars comprise mason jars; and / or the plate glass comprises windshields.

14. The process as defined in any one of claims 1 to 13, wherein the step of forming an aqueous slurry comprises forming a slurry containing between about 5% and about 50% by weight of the starting material.

15. The process as defined in any one of claims 1 to 14, wherein a carbon dioxide solubilizer is added to the aqueous slurry or to the aqueous solution containing alkali metals, wherein the carbon dioxide solubilizer optionally comprises glycerin, and wherein the glycerin is optionally added at a rate of about 6 g per kg of the starting material.

16. The process as defined in any one of claims 1 to 15, wherein TiC>2 is added to the aqueous slurry or to the aqueous solution containing alkali metals, wherein the TiC>2 is optionally added at a rate of about 1% by weight of the starting material.

17. The process as defined in any one of claims 1 to 16, wherein the gas containing carbon dioxide is supplied at a pressure of about 5 to about 150 psi gauge.

18. The process as defined in any one of claims 1 to 17, wherein the gas containing carbon dioxide is supplied to the aqueous solution containing alkali metals in a sparger, a diffuser or a contactor tower.

19. The process as defined in claim 18, wherein the contactor tower is run with the gas and the solution in parallel flow or in counter flow.

20. The process as defined in any one of claims 1 to 19, wherein the gas containing carbon dioxide contains carbon dioxide at a concentration of between about 5% and 100%.21 . The process as defined in any one of claims 2 to 20, wherein the gas containing carbon dioxide is supplied for an initial period, following which pressure is released from a vessel containing the aqueous solution containing alkali metals, following which the gas containing carbon dioxide is reintroduced to the vessel.

22. The process as defined in claim 21 , wherein the gas containing carbon dioxide is supplied for the initial period until the pH of the aqueous solution containing alkali metals reaches a value between about 4.

0. and about 6.0.

23. The process as defined in either one of claims 21 or 22, wherein subsequent to the gas containing carbon dioxide being reintroduced to the vessel, the aqueous solution containing alkali metals is processed for a second period until the pH of the aqueous slurry reaches a level of between about 6.0 and about 7.0.

24. The process as defined in any one of claims 1 to 23, wherein the treatment period comprises between about 15 minutes and about 12 hours.

25. The process as defined in any one of claims 1 to 24, wherein the aqueous solution containing alkali metals is maintained at a temperature in the range of about 10°C to about 80°C during the treatment period.

26. The process as defined in any one of claims 1 to 25, wherein the starting material is glass, and wherein the step of size-reducing the starting material is conducted until the glass has a D50 passing in the range of about 2 pm to about 15 pm.

27. The process as defined in any one of claims 1 to 26, comprising washing the separated solid treated pozzolan with an acid, wherein the acid optionally comprises a strong acid, wherein the strong acid optionally comprises hydrochloric acid, nitric acid, sulfuric acid, hydrobromic acid, hydroiodic acid, chloric acid, or perchloric acid.

28. The process as defined in claim 27, wherein the acid comprises a weak acid, wherein the weak acid optionally comprises acetic acid, formic acid, nitrous acid, or sulfurous acid.

29. The process as defined in either one of claims 27 and 28, wherein the acid is provided at a concentration of between about 2 M to about 18 M.

30. The process as defined in any one of claims 27 to 29, wherein the acid is added at a concentration of about 33% to about 95% by weight.31 . The process as defined in any one of claims 27 to 30, wherein the separated solid treated pozzolan is washed with the acid for a time period between about 0.5 hours and about 2.0 hours.

32. The process as defined in any one of claims 27 to 31 , further comprising rinsing the treated pozzolan after washing the treated pozzolan with the acid, optionally wherein rinsing the treated pozzolan comprises at least two or at least three rinse cycles.

33. A process for removing an alkali metal from glass to be used as supplementary cementitious material, the process comprising conducting a process as defined in any one of claims 1 to 32, wherein the alkali metal is optionally sodium.

34. The process as defined in claim 33, wherein the amount of sodium removed from the glass as the starting material is between about 10% and about 25%.

35. A process for producing a ground glass pozzolan from a glass starting material, wherein the amount of sodium removed from the glass starting material to produce the ground glass pozzolan is in the range of about 5% to about 25%.

36. A process for producing a treated pozzolan from a starting material, the process comprising activating at least one alkali metal in the starting material and washing the activated at least one alkali metal from the starting material using water to produce the treated pozzolan.

37. The process as defined in claim 36, wherein the starting material comprises glass, the at least one alkali metal comprises sodium, and / or the step of activating the at least one alkali metal comprises exposing the starting material to water.

38. The process as defined in either one of claims 36 or 37, wherein the step of activating the at least one alkali metal is conducted after addition of water to the starting material.

39. A pozzolan made by the process as defined in any one of claims 1 to 38.

40. A pozzolan comprising crushed glass having a sodium content of approximately 7.2% to approximately 9.0% by weight.41 . A pozzolan as defined in claim 40 comprising crushed glass having a D50 passing in the range of about 2 to about 15 pm and optionally a carbon content of at least approximately 0.5% by weight.

42. A cement comprising a pozzolan as defined in any one of claims 39 to 41 .

43. The cement as defined in claim 42, wherein the pozzolan is present in an amount of about 5% to about 70% w / w.

44. The cement as defined in either one of claims 42 or 43, comprising Portland cement.

45. Concrete comprising a pozzolan or cement as defined in any one of claims 39 to 44.

46. Concrete as defined in claim 45, wherein the pozzolan is present in an amount of between about 1 % to about 12% by weight on a dry matter basis.

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