Producing sustainable construction materials from byproducts

Abstract

The systems and methods of the present disclosure include a method including mixing a first byproduct including at least one calcium compound and a second byproduct including magnesium to form a first compound and a first reduced byproduct formed from a reaction between the at least one calcium compound and the magnesium, mixing a second compound and the first reduced byproduct to form a third compound and a second reduced byproduct formed from a reaction between the at least one calcium compound and the second compound, converting, by nanofiltration, the second reduced byproduct into at least a first substance and a second substance, and converting, by electrolysis, the first substance into a third substance and a fourth substance.

Description

Atty. Dkt. No. 046434-0978PRODUCING SUSTAINABLE CONSTRUCTION MATERIALS FROM BYPRODUCTS CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority to U.S. Provisional Patent Application No.63 / 747,795, filed on January 21, 2025, the entire disclosure of which is incorporated herein by reference for all purposes.TECHNICAL FIELD

[0002] The present disclosure relates generally to transforming urban and industrial byproducts into sustainable construction materials.BACKGROUND

[0003] Urban and industrial processes, such as desalination and acetylene production, produce waste (e.g., byproducts), such as high-salinity brine or calcium carbide slag (CCS), among others. Both high-salinity brine and CCS may be difficult to dispose of. For example, CCS may be assessed for any residual toxicity or reactivity prior to disposal, and dust control measures may be implemented to mitigate particulate pollution.SUMMARY

[0004] The systems and methods of the present disclosure transform byproducts, such as high-salinity brine and CCS into sustainable construction materials. For example, CCS can be reacted with the high-salinity brine to produce at least magnesium hydroxide (Mg(0H)2) which can be used in sustainable cement. The systems and methods of the present disclosure can generate one or more compounds and substances which can be reused in various processes, or reused in processes to transform the byproducts, providing a circular, sustainable process of reusing byproducts.

[0005] One aspect of the present disclosure is directed towards a method. The method can include mixing a first byproduct including at least one calcium compound and a second byproduct comprising magnesium to form a first compound and a first reduced byproduct formed from a reaction between the at least one calcium compound and the magnesium. The method can also include mixing a second compound and the first reduced byproduct to form14898-1863-4628Atty. Dkt. No. 046434-0978a third compound and a second reduced byproduct formed from a reaction between the at least one calcium compound and the second compound. The method also includes converting, by reverse osmosis and nanofiltration, the second reduced byproduct into at least a first substance and a second substance, second substance including a multivalent ion stream, and converting, by an electrochemical process, the first substance into a third substance and a fourth substance.

[0006] It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts are not mutually inconsistent) are contemplated as being part of the subject matter disclosed herein. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the subject matter disclosed herein.BRIEF DESCRIPTION OF THE FIGURES

[0007] The foregoing and other features of the present disclosure will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only several implementations in accordance with the disclosure and are therefore not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings.

[0008] FIG. l isa flow diagram of an example circular economy of producing sustainable construction materials from byproducts, according to some implementations of the present disclosure;

[0009] FIG. 2 is a flow diagram of an example process for producing sustainable construction materials from byproducts, according to some implementations of the present disclosure;

[0010] FIG. 3 is charts of compression test results of example construction materials, according to some implementations of the present disclosure;

[0011] FIG. 4 is a chart of compression test results of example construction materials, according to some implementations of the present disclosure;24898-1863-4628Atty. Dkt. No. 046434-0978

[0012] FIG. 5 is a charge of a thermogravimetry analysis (TGA) of calcium carbide slag (CCS), according to some implementations of the present disclosure;

[0013] FIG. 6 is perspective views of samples of sustainable construction materials produced from byproducts, according to some implementations of the present disclosure;

[0014] FIG. 7 is a chart of x-ray diffraction (XRD) patterns of powders synthesized from byproducts, according to some implementations of the present disclosure;

[0015] FIG. 8 is photographs of scanning electron microscopy (SEM) of powders synthesized from byproducts, according to some implementations of the present disclosure;

[0016] FIG. 9 is a table of composition of various crystalline phases in the powders synthesized from byproducts, according to some implementations of the present disclosure;

[0017] FIG. 10 is photographs of transmission electron microscopy (TEM) of powders synthesized from byproducts, according to some implementations of the present disclosure;

[0018] FIG. 11 is a chart of compressive strength development of samples of sustainable construction materials produced from byproducts, according to some implementations of the present disclosure;

[0019] FIG. 12 is a chart of thermogravimetric analysis with derivative thermogravimetric analysis (TG-DTG) of different curing conditions of samples of sustainable construction materials produced from byproducts, according to some implementations of the present disclosure;

[0020] FIG. 13 is a table of weight-loss components from TG-DTG deconvolution in samples of sustainable construction materials produced from byproducts, according to some implementations of the present disclosure;

[0021] FIG. 14 is a chart of XRD patterns of different curing conditions of samples of sustainable construction materials produced from byproducts, according to some implementations of the present disclosure;

[0022] FIG. 15 is a chart of Raman spectra of samples of sustainable construction materials produced from byproducts, according to some implementations of the present disclosure;34898-1863-4628Atty. Dkt. No. 046434-0978

[0023] FIG. 16 is a table of deconvolution analysis of samples of sustainable construction materials produced from byproducts, according to some implementations of the present disclosure;

[0024] FIG. 17 is SEM images of at different times during a curing process for compacted samples of sustainable construction materials produced from byproducts, according to some implementations of the present disclosure;

[0025] FIG. 18 is a SEM images of at different times during a curing process for uncompacted samples of sustainable construction materials produced from byproducts, according to some implementations of the present disclosure;

[0026] FIG. 19 is TEM images of compacted and uncompacted samples of sustainable construction materials produced from byproducts, according to some implementations of the present disclosure;

[0027] FIG. 20 is a table of nitrogen adsorption measurements (BET) specific surface area (SSA) of samples of sustainable construction materials produced from byproducts, according to some implementations of the present disclosure;

[0028] FIG. 21 is a flow diagram of an example method for producing sustainable construction materials from byproducts, according to some implementations of the present disclosure; and

[0029] FIG. 22 is a flow diagram of an example method for producing sustainable construction materials from byproducts, according to some implementations of the present disclosure.

[0030] Reference is made to the accompanying drawings throughout the following detailed description. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative implementations described in the detailed description, drawings, and claims are not meant to be limiting. Other implementations may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged,44898-1863-4628Atty. Dkt. No. 046434-0978substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and made part of this disclosure.DETAILED DESCRIPTION

[0031] Embodiments described herein relate generally to producing sustainable construction materials from urban and industrial waste, such as high-salinity brine and calcium carbide slag (CCS). The systems and methods of the present disclosure as described herein may transform the aforementioned waste into magnesium hydroxide (Mg(OH)2) (e.g., brucite), calcium carbonate (CaCOs), sodium hydroxide (NaOH), and hydrochloric acid (HC1). Such products can then be used for various purposes, such as in construction materials or to produce additional brucite, thereby providing a circular and sustainable process.

[0032] Cement is a powder substance that acts as a binding agent when mixed with water, aggregates (e.g., sand), and other materials which then hardens and sets over time. Cement is used in a variety of applications such as for concrete, plastering, structural components of buildings, and the like. Ordinary Portland cement (OPC) is a widely used cement due to the strength, versatility, and relatively low cost of the material, but is also associated with significant carbon dioxide (CO2) emissions produced during the manufacturing process of OPC. Reactive magnesium oxide cement (RMC) is primarily formed of reactive MgO and is used in a variety of applications with a reduced environmental impact compared to OPC due to lower CO2 emissions produced during the manufacturing process. Reactive MgO can be produced by calcining minerals with magnesium at low temperatures (e.g., 600 to 750°C), thus retaining the reactive properties of MgO with water. Alternatively, non-reactive MgO can be produced by calcining the minerals with magnesium at temperatures of 1000°C or more. Calcining the minerals at low temperatures results in a higher reactivity, higher surface area, and greater porosity of the MgO compared to calcining at high temperatures. Brucite can be converted to RMC by calcination.

[0033] Sea water desalination is employed in arid regions such as the Middle East and North Africa (MENA) to address water scarcity. Commonly used desalination methods include thermal, pressure, and electric potential processing of sea water to produce potable water (e.g., fresh, drinking water). However, regardless of the method, desalination generates at least two products: freshwater and a high-salinity byproduct, known as “brine” or “reject brine,” which has a salinity approximately twice that of the source sea water. In addition to54898-1863-4628Atty. Dkt. No. 046434-0978the high content of total dissolved solids (TDS) (e.g., salt) in the brine, desalination brine is often at a higher temperature than the freshwater and contains chemical residues from pretreatment (e.g., cleaning and biofouling), as well as anti-scaling and anti-foaming agents. High-salinity brine may have a TDS of greater than 50,000 milligrams per liter (mg / L).

[0034] Conventional disposal strategies for the brine are primarily based on cost and location, including direct disposal to the sea, deep well discharge, evaporation ponds, and land applications. Continuous discharge of brine into water bodies can increase the salinity and temperature of the water bodies, adversely affecting the environment and marine life. With the high number of desalination plants in the Gulf region producing approximately 55% of the global reject brine, amounting to around 142 million meters cubed (m3) brine per day, reject brine is a major urban waste and environmental concern. Therefore, safe disposal of brine produced in the desalination process remains an economic challenge as the brine may need to be treated and diluted to mitigate increases in temperature or salinity levels if disposed into the ocean or sewage systems. The brine may need to be treated given the TDS discharge limits for such disposal ranging from 1,000 to 3,000 ppm. Sustainable alternatives and treatment solutions may be employed to appropriately manage desalination brine and its disposal to sea within a safe TDS limit.

[0035] Mineral recovery from the desalination brine may be a solution for management and utilization of the desalination brine. The brine solution contains various cations such as Na+, Mg2+, K+, Ca2+, Li+, B3+, Rb2+, and Cs2+, and anions such as SC2-, Cl“, HCCh-, CCh2-, NO3“, Br“, and 1“ which can be converted to minerals. Specifically, magnesium (Mg2+) and calcium (Ca2+) ions can be recovered in the form of magnesium hydroxide (brucite, Mg(0H)2) and calcium carbonate (CaCCh), which are both used for, for example, cement production. Brucite can be calcined at temperatures between 400-500°C to convert the brucite to RMC, which can be a sustainable alternatives to OPC due to a lower production temperature (700-900°C), ability to gain strength through CO2 sequestration, and recyclability. Conventionally, commercial production of RMC involves calcination of naturally occurring mineral magnesite (MgCCh), resulting in significant CO2 emissions. Therefore, alternative methods for RMC production from brucite may improve energy efficiency and reduce the carbon footprint of the production process. CaCCh may be a supplementary cementitious material (SCM) and a constituent of limestone calcined clay cement (LC3), another possible sustainable alternative to OPC.64898-1863-4628Atty. Dkt. No. 046434-0978

[0036] Recovery of brucite or MgO from concentrated brine solutions can be achieved through the utilization of a base or precipitation agent. The use of a strong base increases the pH of the brine solution to favor the formation of Mg(0H)2. Various precipitation agents, such as but not limited to calcium oxide (CaO), sodium hydroxide (NaOH), ammonium hydroxide (NH4OH), and ethanolamine (C2H5OHNH2), can be employed to produce brucite from the reject brine which can be subsequently converted to RMC through calcination. Conventional methods focus on characterizing the MgO synthesized through the precipitation process and examining the influence of reaction parameters on the porosity, reactivity, and performance as a binder of the MgO for construction applications. RMC synthesized through the precipitation route from desalination reject brine can exhibit higher dissolution and reactivity, resulting in greater strength compared to commercial counterparts. However, lifecycle analyses (LCA) suggest that synthetic MgO production has a higher CO2 impact due to the alkali production, processing steps, and calcination. Hence, direct application of brucite without calcination can lower CO2 emissions. Direct carbonation of brucite under concentrated CO2 conditions may have rapid strength development up to 30 MPa, making the brucite suitable for construction applications. Ammonium acetate modifiers can be used to increase the reactivity of brucite powders, which may result in an almost two-fold increase in the strength of the sample compared to unmodified brucite.

[0037] LCA studies have also found that more than 80% of the equivalent CO2 emissions in the brucite production process are associated with the carbon footprint of the utilized precipitation agent. Therefore, reducing the emissions from precipitation agents such as CaO or identifying sustainable alkali sources may be an efficient way to improve the CO2 impact of brucite production through precipitation. Calcium carbide slag or residue (CCS), a solid waste from the acetylene (C2H2) (e.g., used in chemical manufacturing) production process, may be an alternative to the conventional precipitation agents used for brucite synthesis from reject brine. CCS primarily includes calcium hydroxide (Ca(OH)2) and CaCOs, with small amounts of carbon and silicate. Due to the availability of Ca(OH)2 in the CCS, the pH of the brine can be enhanced (e.g., increased) to precipitate the Mg(OH)2. Globally, the demand for acetylene is high due to the usage of acetylene as a raw material for many processes, including chemical synthesis, polyvinyl chloride (PVC) production, metalworking, welding and cutting, and carbon coatings, resulting in around 40 million tons of CCS being produced annually. The CCS generated as a waste of the acetylene industry is mainly disposed in landfills, leading to environmental pollution.74898-1863-4628Atty. Dkt. No. 046434-0978

[0038] Therefore, locally produced CCS (e.g., CCS produced in the Gulf and UAE region) can be utilized directly as a resource for the production of magnesium-based construction material (e.g., RMC). 10 grams (g) of CCS may produce approximately 10g of brucite-based powders per liter of brine. Such approach replaces the commonly used precipitation agent calcium oxide (CaO) which increases CO2 emissions of the brucite production process. Brucite produced from CCS can address the demand for non-structural construction materials. Further, due to an overall low global utilization of CCS as a resource, CCS can be acquired from other regions (e.g., regions other than the Gulf and UAE region) to process higher quantities of brine and produce higher quantities of, for example, brucite. Additionally, NaOH produced from brine solution using electrolysis can also be used as a precipitation agent.

[0039] The utilization of CCS not only significantly reduces the CO2 footprint associated with CaO production, but also enhances the technical properties of the produced construction materials. The high percentage of calcium hydroxide (Ca(OH)2) in the CCS increase the pH of the brine solution to favor the formation of brucite, while impurities in the CCS (e.g., calcium sulfate hemihydrate, calcium carbonate, etc.) enhances the nucleation effect in the brucite, resulting in a densified cementitious matrix when the brucite is used as a construction material.

[0040] Further, CaCCh can be utilized as an SCM for OPC. OPC can be replaced by up to 30% of CaCCh to create concrete with suitable (e.g., similar) mechanical performance (e.g., to OPC without CaCOs). The addition of CaCOs into concrete can accelerate the reaction rate of OPC. Calcium carboaluminate hydrates as hemicarbonate aluminate, and monocarbonate aluminate can also form when CaCOs is added to OPC. Further, the incorporation of CaCOs into fly ash (e.g., byproduct of burning coal) and OPC mixes can accelerate and amplify early-age hydration reactions (e.g., cement hydration) by serving as nucleation sites, which can alleviate the delayed setting times induced by a high volume of fly ash. In addition, CaCOs is also a constituent of limestone calcined clay (LC3) cement (e.g., 15-20%) and a sustainable alternative to OPC. The combination of different constituents of LC3creates a synergistic effect to enhance mechanical performance and simultaneously reduce the overall CO2 footprint compared to OPC.

[0041] CaCOs produced from reject brine may be a resource with many applications in the construction industry. Indirect mineral carbonation can be used to sequester CO2 to form84898-1863-4628Atty. Dkt. No. 046434-0978CaCCh using a Ca-rich solution and an alkali to increase the pH of the solution. Methods may be implemented to extract the CaCCh. A first example method can be a direct precipitation process in a continuous mode configuration, where commercially available Na2CCh can be used to recover CaCCh. A second example, potentially more energy-efficient method involves CO2 passing into a basic NaOH stream to produce a Na2CCh stream for CaCCh recovery from a Ca-rich brine.

[0042] Efficient management and safe disposal of major urban and industrial waste products are becoming necessary due to the environmental and ecological concerns associated with current disposal practices of the waste products. The systems and methods of the present disclosure aim to utilize at least two such locally (e.g., local to at least the UAE) abundant urban and industrial byproducts as resources for the production of sustainable materials for industrial applications. The byproducts can include (i) high-salinity reject brine produced as a byproduct of the desalination process and (ii) calcium carbide slag (CCS) produced as a byproduct of the acetylene production process. The systems and methods of the present disclosure can transform byproducts into valuable resources for various industries, such as construction and chemical industries, thus reducing environmental pollution and promoting sustainable development and circular economy practices. In addition to producing environmentally friendly (e.g., sustainable) construction materials and industrial chemicals, a low-TDS brine stream can be produced which is suitable for safe disposal back into the sea. Low-TDS brine can be defined as brine including a TDS of 10,000 mg / L or less.

[0043] The systems and methods embody principles of circular systems (e.g., minimizing waste and maximizing resources) by reducing the use of input resources and simultaneously minimizing waste, pollution, and carbon emissions. The systems and methods transform the linear process associated with sea water desalination, which typically results in the direct disposal of reject brine, into a circular process by extracting valuable minerals from the reject brine. The systems and methods leverage widely available byproducts in, for example, the MENA region, and process the byproducts to extract minerals of commercial value. Similarly, the utilization of CCS promotes the circular process by repurposing the CCS as a valuable resource instead of disposing of the CCS as waste.

[0044] The systems and methods of the present disclosure aim to achieve a brine processing capacity of, for example, 4,000 liters per day and produce brucite (Mg(0H)2) and calcium carbonate (CaCCh) along with sodium hydroxide (NaOH), hydrochloric acid (HC1),94898-1863-4628Atty. Dkt. No. 046434-0978low-TDS brine, and freshwater. The performance of brucite, and calcium carbonate can be evaluated for construction applications. Concrete blocks produced from brucite-based materials can be cured under CCh-rich environments to enhance strength development and achieve permanent carbon sequestration. The CaCCh produced can be utilized as a supplementary cementitious material and a principal component of the limestone calcined clay cement (LC3). NaOH can be used as a supplemental source for generating Mg(0H)2 or in other industrial applications. Similarly, the HC1 can neutralize the low-TDS brine stream before the stream is released to the sea and can be used by other industries.

[0045] The systems and methods of the present disclosure: (i) demonstrate a scalable, continuous (e.g., circular) process for the recovery of valuable minerals from byproduct streams, (ii) provide a sustainable solution to brine disposal issues faced by the desalination industry, (iii) introduce a circular system model to both the desalination and acetylene industries, transforming byproducts into valuable resources, and (iv) enhance the understanding of using low-TDS brine in construction, potentially reducing freshwater usage and associated environmental impacts. The systems and methods significantly positively impact target populations by: (i) reducing environmental pollution through efficient byproduct utilization, (ii) lowering the cost of construction materials by providing locally produced alternatives, (iii) decreasing the reliance on freshwater for construction, conserving water resources in arid regions like the UAE, and (iv) promoting sustainable industrial practices and contributing to sustainability goals, such as regional sustainable goals.

[0046] Furthermore, the systems and methods can leverage sunny and warm desert climates, further enhancing the efficiency and sustainability. For example, drying of wet powders in post-processing steps can be achieved in natural outdoor conditions. The wet powders may also be dried in an environmental chamber.

[0047] FIG. 1 is a flow diagram of an example circular process 100 achieved by the systems and methods of the present disclosure. A desalination process 102 transitions from a linear to a circular process (e.g., at least a portion of the circular process 100) by extracting various compounds and substances from a second byproduct 104 including desalination reject brine (e.g., effluent brine, high-salinity brine, waste brine). The desalination process 102 can receive sea water 106 as an input, and can separate the sea water 106 into potable water 108 (e.g., drinking water, fresh water) and the second byproduct 104. The sea water 106 may be collected from a body of water, such as a sea, ocean, or gulf.104898-1863-4628Atty. Dkt. No. 046434-0978

[0048] From the second byproduct 104, the process 100 can include precipitating compounds out of the second byproduct 104 to extract the compounds. The extracted compounds can include a first compound 110 including Mg(OH)2 and a third compound 112 including CaCCh. During the precipitation of the first compound 110, the second byproduct 104 can be reduced into a first reduced byproduct 114, such that the first reduced byproduct 114 is the second byproduct 104 without magnesium (e.g., magnesium is reduced or precipitated out from the second byproduct 104). The first compound 110 can be precipitated out of the second byproduct 104 by using a first byproduct 105. The first byproduct 105 can include CCS, and can be a byproduct of the acetylene industry.

[0049] The first reduced byproduct 114 can be used to precipitate the third compound 112. During the precipitation of the third compound 112, the first reduced byproduct 114 can be reduced into a second reduced byproduct 116, such that the second reduced byproduct 116 is the second byproduct 104 without magnesium or calcium (e.g., magnesium and calcium are reduced or precipitated out of the first reduced byproduct 114). In some implementations, a second compound (e.g., second compound 211) is used to facilitate precipitation of the third compound 112. For example, the second compound is a precipitation agent.

[0050] A plurality of substances can be extracted from the second reduced byproduct 116 using at least a plurality of membranes (e.g., membranes 219). The extracted substances can include a first substance 118 including NaCl and a second substance 120 including freshwater and low-TDS brine. Low-TDS brine can be defined as brine including a TDS of 10,000 mg / L or less. The plurality of membranes can be included and implemented in nanofiltration (NF) and reverse osmosis (RO). For example, the first substance 118 and the second substance 120 can be extracted from the second reduced byproduct 116 via NF. The first substance 118 can be further separated into a third substance 122 including NaOH and a fourth substance 124 including HC1 via electrolysis performed by, for example, an electrolyzer. The third substance 122 can be used to facilitate precipitation of the first compound 110 and the third compound 112. The second substance 120 can be separated into a fifth substance 126 including the freshwater and a sixth substance 128 including the low-TDS brine via RO. The fifth substance 126 can be used as potable water 108. The fifth substance 126 can also be used in various applications, such as construction.

[0051] Mg(OH)2 and CaCOs can be directly used for various purposes, such as in the construction industry. Furthermore, the acetylene industry, which generates a first byproduct114898-1863-4628Atty. Dkt. No. 046434-0978105 including CCS, can be transformed into a circular process by utilizing the CCS in the recovery (e.g., precipitation, generation) of Mg(0H)2. The NaOH generated at the end of the process 100 can also be re-used as a precipitation agent in a first stage (e.g., first stage 206) and second stage (e.g., second stage 208) during the extraction of Mg(0H)2 and CaCCh, enabling the extraction of larger volumes of Mg(0H)2 and CaCOs from the reject brine without acquiring NaOH from other sources. The NaOH extracted from the second byproduct 104 can supplement (e.g., reduce) the amount of CCS used for Mg(OH)2 extraction. Another advantage of the systems and methods of the present disclosure is that the systems and methods generates low-TDS brine (e.g., the fifth substance 126), which can be used in construction applications. Currently, desalinated water is used in construction since water containing ions such as chloride may harm concrete. However, low-TDS brine may be used with construction materials such as brucite or RMC or even traditional binders such as OPC or LC3directly without compromising the properties of the concrete. Using low-TDS brine can lower the water usage and, thereby, the energy usage and CO2 emissions, of the construction industry.

[0052] FIG. 2 is a flow diagram of an example system 200 for implementing the process 100 for recovering minerals (e.g., compounds and substances) from brine. The system 200 recovers Mg2+, Ca2+, Na+, and Cl" ions in the form of Mg(OH)2 (e.g., first compound 110), CaCO3 (e.g., third compound 112), NaOH (e.g., third substance 122), and HC1 (e.g., fourth substance 124), respectively, utilizing desalination reject brine 202 (e.g., second byproduct 104) and calcium carbide slag (CCS) 204 (e.g., first byproduct 105). The high concentration of the four ions in the reject brine 202 ensures a high yield of these products, such as a recovery of at least 80% of the ions in the brine 202.

[0053] As shown in FIG. 2 and as described herein, the system 200 may include four stages. A first stage 206 and a second stage 208 can utilize chemical synthesis reactors 210 (e.g., precipitation reactors, etc.) operating in a continuous mode to extract at least brucite (Mg(OH)2) 212 (e.g., first compound 110) and calcium carbonate (CaCCh) 214 (e.g., third compound 112), respectively. Operation in a continuous mode may refer to the reactors 210 continually receiving input (e.g., reject brine 202 and CCS 204) and producing output (e.g., Mg(OH)2212 and brine 236) . For example, the system 200 includes a first reactor 210 to extract brucite 212 and a second reactor 210 to extract CaCOs 214. The first stage 206 can include a precipitation process to recover Mg(OH)2212 from reject brine 202 using CCS 204124898-1863-4628Atty. Dkt. No. 046434-0978as a resource and precipitation agent. In the second stage 208. the Ca-rich effluent brine 236 (e.g., first reduced byproduct 114) may be utilized to recover CaCCh 214 by employing a second compound 211, such as Na2CCh, as a precipitation agent.

[0054] In a third stage 216, membrane-based NF 218 (e.g., plurality of membranes 219, at least a portion of a plurality of membranes 219) and RO 220 (e.g., plurality of membranes 219, at least a portion of a plurality of membranes 219) can be employed to produce a NaCl-rich stream 222 (e.g., first substance 118, liquid), freshwater 224 (e.g., fifth substance 126), and a low-TDS stream 226 (e.g., portion of the second substance, sixth substance 128). For example, NF 218 and RO 220 separates the brine 238 (e.g., second reduced byproduct 116) into multiple streams (e.g., substances). As shown in FIG. 2, the NF 218 separates the brine 238 into NaCl 222 and a multivalent stream 242 (e.g., the second substance). The multivalent stream 242 can be separated into freshwater 224 and low-TDS brine 226 by RO 220.

[0055] The system 200 can include an electrolyzer 230. A fourth stage 228 can involve the electrolyzer 230 to perform electrolysis on the NaCl-rich stream 222 to produce one or more substances, namely sodium hydroxide (NaOH) 232 (e.g., third substance 122) and hydrochloric acid (HC1) 234 (e.g., fourth substance 124), which may both be used for various industrial application, such as in chemicals or textiles. NaOH 232 can be used for the precipitation processes in both the first stage 206 and the second stage 208, such as for the production of Na2CO3211. HC1 234 can be used to neutralize the low-TDS stream 226 for safe disposal into a body of water. The system 200 can include a mixer 240. The HC1234 can be mixed using the mixer 240 with the low-TDS brine 226 to produce a neutralized low-TDS brine 244.

[0056] Each of the first stage 206, the second stage 208, the third stage 216, and the fourth stage 228 can include techniques such as reactive seeded crystallization for enhanced recovery, energy efficiency of continuous mode processes, and pressure and volume flow adjustments. Each of the first stage 206, the second stage 208, the third stage 216, and the fourth stage 228 can operate under ambient conditions, thus eliminating environmental concerns regarding temperature increase in sea water when disposing of the brine (e.g., brine 244). All the reactions (e.g., stages 206, 208, 216, 228) can be processed in a continuous flow configuration, allowing for higher processing capacity, low reaction time, and low operational costs compared to non-continuous configurations. Each fluid or substance of the system 200 may be located in a storage tank 209. For example, at least one of the reject brine 202, the134898-1863-4628Atty. Dkt. No. 046434-0978brine 236, the brine 238, the multivalent stream 242, the freshwater 224, the low-TDS brine 226, the NaCl 222, the NaOH 232, the HC1 234, or the neutralized brine 244 is located in a respective storage tank 209.

[0057] Referring further to FIG. 2, the first stage 206 can involve the utilization of the Ca(OH)2-containing calcium carbide slag (CCS) 204 to precipitate brucite-based composite powders 212 from the reject brine 202 of the desalination process. The high pH (e.g., greater than 11) generated from the Ca(OH)2 (e.g., calcium compound) in CCS 204 solutions is expected to result in high recovery (e.g., greater than 80% of Mg ions present in brine 202) and yield of brucite. Utilization of CCS 204 can also ensure a higher concentration of Ca2+ions (e.g., 20% or greater increase in Ca ions from brine 202) in the effluent brine 236 after the first stage 206, which can be recovered using the appropriate filtration method (e.g., NF 218).

[0058] As shown in FIG. 2, in the first stage 206, a chemical precipitation reactor 210 operating in a continuous flow configuration can be utilized for recovery of Mg(OH)2 212 from reject brine 202 (e.g., high-salinity brine, effluent brine, waste, byproduct). The reject brine 202 may have a salinity of at least twice as much has sea water (e.g., 106), and the reject brine 202 may have a TDS of greater than 50,000 mg / L. The first stage 206 can recover (e.g., generate, extract) brucite 212. The flow of the reactants (e.g., reject brine 202 and CCS 204) can be adjusted to limit the residence time (e.g., time within the reactor 210) between 30 minutes to 1 hour and to obtain a brine processing capacity of, for example, 4,000 liters per day. In some implementations, the residence time is less than 30 minutes or greater than 1 hour. In some implementations, the brine processing capacity is less or greater than 4,000 liters per day.

[0059] Reject brine 202 can be filtered to remove dust and other particulate impurities before utilization in the reactor 210. CCS 204 (e.g., locally obtained CCS 204) can be characterized through X-ray diffraction (XRD) and thermogravimetry (TG) analysis for quantification of crystalline phases. The CCS 204 can be dried, for example, under natural sunny conditions or in an environmental chamber, to remove the moisture. In addition, depending on the content of Ca(OH)2 in the CCS 204, the CCS 204 can be dissolved in water to make a slurry prior to combining with the reject brine 202. The CCS 204 content in the slurry can be, for example but not limited to, 50 mL of slurry containing 10 to 13 grams of CCS 204 per liter of brine 202.144898-1863-4628Atty. Dkt. No. 046434-0978

[0060] Room temperature (e.g., 20-25 degrees Celsius) and constant stirring rates may be utilized for the reaction. For example, the CCS 204 and the brine 202 are mixed at a constant rate at room temperature. Seeded reactive crystallization may also be implemented by recirculating a portion of at least one of the CCS 204 or the brine 202 at a pre-determined flow rate. Through the recirculation dynamics, seeded crystallization can occur which may enhance the effectiveness (e.g., amount of recovered brucite 212, etc.) of the first stage 206. The factors that can affect the reaction dynamics, such as CCS 204 slurry concentration, stirring speed, residence time, and flow rate of the recirculated solution, can be optimized (e.g., adjusted, calculated) to achieve an enhanced precipitation rate, complete homogenization, and recovery of brucite. Such factors and parameters can depend on a size (e.g., volume) of the precipitation reactor 210 and the circulating volume and contents being reacted in the precipitation reactor 210. For example, the concentration of magnesium may affect how much CCS 204 will be used in the slurry which can be in a range 10 to 13 grams of CCS 204 per liter of brine 202. Specific ranges can be tested to determine the ranges of the factors that affect reaction dynamics, such as but not limited to, slurry concentration (e.g., 50 to 300 grams of CCS 204 per liter of water), stirring speed (e.g., 100 to 400 revolutions per minute (RPM), for a 120-liter volume reactor 210), residence time (e.g., 10 mins to 2 hours), and flow rate of the recirculated solution (e.g., 0.05 to 0.2 liters per minute (LPM)).

[0061] The resulting solution after mixing the CCS 204 and the brine 202 may undergo postprocessing to complete the Mg(OH)2212 recovery. For example, centrifugation may be utilized to separate precipitated brucite 212 and the reject brine 202. The effluent brine 236 (e.g., brine 202 without magnesium) may be directed to the second stage 208, as shown in FIG. 2. The wet brucite powders may be washed by centrifugation using a volume of water to remove reaction byproducts and impurities. The amount of water used for the washing can determine the overall purity of the brucite powders 212. For example, as the water used increases, the purity of the brucite powders 212 increases. The amount of water used can be based on a minimum brucite powder 212 purity that can be used in construction applications to mitigate increased water usage.

[0062] After postprocessing (e.g., centrifugation), the wet powders can be collected and dried to remove the excess water. The obtained brucite powders 212 and effluent brine 236 can be characterized to quantify the recovery and physio- chemical properties of the reactants and products. Brucite-based powders 212 obtained from the reaction can be performance154898-1863-4628Atty. Dkt. No. 046434-0978tested for construction applications by curing the brucite powders 212 under concentrated CO2 conditions for subsequent strength development through permanent CO2 sequestration. The performance assessment can confirm the suitability of brucite-based materials produced using CCS 204 for application as a sustainable binder.

[0063] In some implementations, the first stage 206 can include characterization of the CCS 204 obtained from acetylene production industries (e.g., using XRD, TG, crystalline phase analysis / composition) and characterization of the effluent brine 202 obtained from the desalination plant (e.g., inductively coupled plasma optical emission spectrometer (ICP-OES), chemical composition). X-ray diffraction (XRD) is an analytical technique that identifies and characterizes crystalline materials by measuring the pattern and intensity of X-rays diffracted by their atomic lattice. Thermogravimetry (TG) is a thermal analysis technique that measures changes in a material’s mass as a function of temperature or time under a controlled atmosphere.

[0064] The first stage 206 can also include analysis of the recovery and final yield of brucite-based powders 212 from the precipitation reactor 210 using the continuous flow configuration. The analyzed parameters may include the concentration of CCS 204 slurry, rotation speed, residence time, flow rate of recirculated reaction solution, etc., characterization of the recovered brucite powders 212 for their purity and microstructural properties (e.g., x-ray diffraction (XRD), thermogravimetric analysis (TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM)), and characterization of the effluent brine 236 after the precipitation (e.g., ICP-OES spectrometer, chemical composition).

[0065] In some implementations, the results of the first stage 206 can include identification of the parameters impacting the reaction operated in a continuous flow configuration to achieve maximum reaction rates and recovery, applicability of the CCS 204 as a precipitation agent for high recovery of Mg from reject brine 202, and determining a residence or reaction time for the continuous flow reactor configuration to achieve a complete reaction. The residence time calculation determines the total amount of reject brine 202 that can be processed daily for the recovery of brucite-based powders 212. The results can also include efficiency of the first stage 206 for selective recovery of magnesium hydroxide and properties of the brine 202 after the first stage 206 for use in the second stage 208. The parameters can include slurry concentration, flow rate of slurry and brine 202 affecting the164898-1863-4628Atty. Dkt. No. 046434-0978residence time, and stirring speed to find conditions for maximum reaction efficiency (e.g., maximum Mg removal).

[0066] The recovery of Mg(0H)2 212 from reject brine 202 can be achieved through reactive crystallization, where Mg2+reacts with OH" ions to form brucite or Mg(OH)2 212, precipitating due to low solubility. Any precipitation agent or alkali which can increase the pH of the solution (e.g., reject brine 202) above 9 can be used in at least the first stage 206. However, utilization of the alkalis may use energy and CO2. Therefore, the precipitation of Mg(OH)2 212 can be achieved by utilizing CCS 204, which contains high amounts of Ca(OH)2 to increase the pH of the solution (e.g., brine 202). Since CCS 204 includes CaCCh 214 and small amounts of carbon and silicate, other than Ca(OH)2, the reaction products are expected to have a lower purity. However, since the goal of the systems and methods is to utilize the recovered brucite 212 for construction applications, a reduction in purity is not expected to affect performance.

[0067] The second stage 208 can involve the precipitation of CaCCh 214 from the Ca-rich and Mg-free brine 236 (e.g., first reduced byproduct, effluent Ca2+-rich brine 236) recovered from the first stage 206 using a precipitation agent, such as Na2CCh 211. CaCCh 214 is usually recovered from industrial byproduct streams using mineral carbonation, where CO2 reacts with Ca2+to produce thermodynamically stable and insoluble calcium carbonate 214. Alkali solutions can also be used for the precipitation of CaCCh 214. In the second stage 208, CaCCh 214 can be precipitated by using Na2CCh 211 as an alkali, such as in the precipitation reactor 210. Due to the non-availability (e.g., lack, etc.) of the Mg2+ions in the effluent brine 236 of the second stage 208, high-purity CaCCh 214 (e.g., 98 weight percent (wt.%) or more CaCCh) can be produced in the second stage 208, which can be used for construction and other industrial applications. In addition, the availability of a Ca2+-rich stream can also help to reduce the energy utilization for the reaction and post-processing procedures.

[0068] The recovery of calcium from the effluent brine 236 of the first stage 206 can be achieved using a similar precipitation reactor 210 employed in the first stage 206 operating in a continuous flow configuration. Due to the utilization of the CCS 204, the effluent brine 236 from the first stage 206 will be rich in Ca (e.g., have 20% or more Ca ions than the brine 202). A filtration process can be implemented to filter any impurities and byproducts from the effluent brine 236 before utilization in the second stage 208. Na2CCh 211 may be utilized174898-1863-4628Atty. Dkt. No. 046434-0978as an alkali to increase the effluent brine 236 pH for forming the mineral CaCCh 214, an insoluble compound that precipitates immediately. Unlike CCS 204, Na2CCh 211 has a high solubility in water. Therefore, a concentrated solution (e.g., 100 to 300 grams of Na2CCh 211 per liter) may be utilized as a reactant. An amount of reactant solution (e.g., 5 to 20% volume of effluent brine 236) may be recirculated to achieve seeded reactive crystallization for enhanced reaction rates (e.g., reaction efficiency based on, for example, product yield and brine after reaction) and a residence time. The Na2CCh 211 stream may be at least one of a: (i) a commercially available Na2CCh 211 or (ii) a NaOH solution saturated with CO2 to form the Na2CCh 211 stream. Similar to the first stage 206, all the reaction parameters (e.g., alkali solution concentration, stirring speed, residence time, and flow rate of the recirculated solution) can be optimized to maximize the recovery and yield of CaCCh. For example, the reaction parameters can be adjusted by testing factors in a specific range, and adjusting the factors based on product yield (e.g., of CaCCh) and brine 236 following the reaction. In some implementations, a yield of CaCCh 214 may be approximately 10 to 12 grams per liter of brine 236 in response to using 8 to 9 grams of Na2CCh 211 per liter of brine 236. In some implementations, the yield is less than 10 or greater than 12 grams, and the Na2CCh is less than 8 or greater than 9 grams.

[0069] CaCCh 214 can be separated from the brine 236 using centrifugation, and collected CaCCh 214 powders can be dried. As the brine 236 in the second stage 208 has no Mg present, the CaCCh 214 formed in the second stage 208 is expected to have higher purity (e.g., little to no Mg, etc.) than the Mg(OH)2 212, and little or no washing may be used. The CaCCh powders 214 may be characterized for physio-chemical properties. The performance of CaCCh 214 powders may be assessed as supplementary cementitious material to OPC or as a constituent of LC3cement.

[0070] In some implementations, the second stage 208 can include analysis of the reaction parameters (e.g., Na2CCh 211 concentration, residence time, and rotation speed) to maximize calcium carbonate recovery, carbonation of NaOH solution for the production of Na2CO3211 solution, characterization of the recovered calcium carbonate for purity and microstructural properties and comparison of the efficiency of the two sources of Na2CO3 211, and characterization of the effluent brine for the chemical composition (e.g., ICP-OES spectrometer).184898-1863-4628Atty. Dkt. No. 046434-0978

[0071] Results of the second stage 208 can include parameters that affect the yield of calcium carbonate 214, processing capability of the reactor for brine utilization per day with maximized yields and optimal conditions, estimation of cost and energy utilization of the recovery of both the products for commercial and environmental viability, and properties of the brine 238 (e.g., chemical composition) after the second stage 208 (e.g., ICP-OES spectrometer). A maximum yield of the second stage 208 corresponds to a recovery of greater than 99% of CaCCh 214. The flow rates may depend on a volume of NaOH solution.

[0072] In the third stage 216, effluent brine 238 (e.g., brine 202 without magnesium or calcium, second reduced byproduct) from the second stage 208 can be processed through NF 218 and RO 220 steps, and a NaCl-concentrated solution 222 obtained after the NF 218 can be utilized to produce an acid (e.g., HC1) 234 and a base (e.g., NaOH) 232 stream by employing the electrolyzer 230 (e.g., electrochemical reactor) to perform an electrolysis process. In the third stage 216, NF 218 may be utilized for the rejection of monovalent ions and the generation of NaCl 222 (e.g., first substance) and multivalent ions streams 242 (e.g., second substance). The multivalent ion stream 242 can be a liquid with multiple positively or negatively charged ions.

[0073] The Mg- and Ca-free effluent brine 238 from the second stage 208 can be processed using NF 218 and RO 220 to generate a monovalent NaCl concentrated stream 222, multivalent stream 242, and freshwater 224. The systems including the membranes 219 for NF 218 and RO 220 can use housings and pumps to generate a flow for processing the effluent brine 238. The NF 218 membrane has a high multivalent rejection (e.g., greater than 97% rejection) such that only the monovalent permeates the membrane. The NF 218 step may result in a permeate NaCl stream 222 and retentate multivalent stream 242. The NF 218 step can be optimized to obtain high efficiency of the permeate NaCl stream 222 by recirculating the retentate feed into the inlet feed. For example, the NF 218 can be adjusted based on a flow rate of the NaCl stream 222 through the membranes and a number of cycles of the NaCl stream 222 being recirculates. The flow rate can depend on a membrane module used for application. High efficiency can refer to a high concentration of obtained NaCl 222. The feeds obtained from the NF 218 step can be provided to the RO 220 membrane to obtain more concentrated monovalent, multivalent streams 242, and freshwater 224.

[0074] In some implementations, the third stage 216 can include a continuous chemical composition analysis of the brine 226 after NF 218 and RO 220 steps to optimize the output194898-1863-4628Atty. Dkt. No. 046434-0978for multivalent and monovalent streams for the next stage (e.g., fourth stage 228) and further processing (e.g., with an ICP-OES spectrometer) and optimizing flow rates for increased energy efficiency of the NF 218 and RO 220 steps. The flow rate can be optimized by varying solution flow through the membrane from a minimum to a maximum allowable energy. The output can be adjusted by controlling a number of times the streams remain in NF 218 and RO 220, respectively. The results of the third stage 216 can include obtaining flow conditions for NF 218 and RO 220 steps for energy-efficient recovery of monovalent and multivalent streams from the effluent stream 238 of the third stage 216 and properties of the obtained streams (e.g., NaCl 222 and brine 226) after the third stage 216.

[0075] In the fourth stage 228, the concentrated NaCl stream 222 may be introduced to an electrolyzer 230 to electrolyze the NaCl 222 and generate NaOH 232 (e.g., third substance) and HC1 streams 234 (e.g., fourth substance). Monovalent ions stream 242 can be subjected to a RO 220 process for freshwater 224 generation and low-TDS brine 226 for concrete mixing or disposal into a body of water. NaOH 232 and HC1234 can be utilized to precipitate brine in the first stage 206 (e.g., brine 202) or the brine 226, and neutralize the high-pH brine (e.g., brine 202 or 226) before its disposal, respectively.

[0076] The NaCl concentrated stream 222 obtained after the third stage 216 can be processed using the electrolyzer 230 to split the NaCl 222 and generate NaOH 232 and HC1 234 streams. The electrolyzer 230 can use bipolar membrane electrodialysis (BMED) and membrane-less electrolysis to recover NaOH 232 and HC1 234 from NaCl 222. In some implementations, the electrolyzer 230 includes at least a portion of the plurality of membranes 219. The energy efficiency, cost, and long-term operation for both processes can be analyzed. Such analysis can be conducted based on capital cost of processes, energy consumption, and concentration of obtained chemicals (e.g., NaOH 232 and HC1 234). In addition, the concentration of the NaOH 232 and HC1 234 streams can also be determined. In some implementations, the electrolyzer 230 include a membrane-less electrolyzer which may not include a membrane between the anode and cathode at high current density and processes higher volumes in smaller areas compared to electrolyzers with membranes.

[0077] The electrolyzer 230 can include an electrodialysis (ED) stack based on the bipolar membrane (BPM) to produce acid and base from the NaCl stream 222. Depending on the cell design, the BMED stack may contain one or more units including at least a cation exchange membrane (CEM), a BPM, and an anion exchange membrane (AEM). Acid and base204898-1863-4628Atty. Dkt. No. 046434-0978production can be performed galvanostatically at a specific cell current or current density range. The concentration of the feed solutions (e.g., NaCl 222) can be determined using an ICP-OES spectrometer. Since Mg and Ca would have been recovered in the previous stages 206 and 216, the fouling of the membranes to increase the long-term operation of the cell may be reduced. In some implementations, the system 200 may employ a membrane-less electrolyzer 230 that eliminates membranes for acid and base production.

[0078] In the electrolyzer 230 setup, two porous electrodes may be placed in parallel. The Hz-saturated NaCl 222 stream may flow between the electrodes, and NaOH 232 and HC1234 are produced at the cathode and anode, respectively. The electrolyzer 230 inlet port may be connected to the feed NaCl 222 tank, saturated with Hz, and outlet ports with effluent collection containers. After filling the cell with inlet NaCl 222 solution, electrodes may be subjected to different voltametric cycles at certain sweeping voltage ranges and scan rates to find steady-state operation voltage. Recovery of the Mg and Ca in the previous stages 206 and 208 can also increase the efficiency of the electrodes for the process 200 due to the minimal formation of metal hydroxide during operation. The NaOH 232 stream produced from the fourth stage 228 can be used to further precipitate the brine 202 for Mg(OH)z 212 production or carbonated to NazCOs 211 and used for the precipitation of CaCOs 208 in the second stage 208. The HC1234 stream can neutralize the low-TDS stream 226 obtained after the RO 220 step to create a neutralized low-TDS stream 244 (e.g., neutralized sixth substance) before disposal. The HC1 234 can be mixed with the low-TDS stream 226 in a mixer 240 to produce the neutralized low-TDS stream 244.

[0079] In some implementations, the fourth stage 228 can include a continuous chemical composition analysis of the inlet brine (e.g., brine post NF 218 and post RO 220) to measure the reduction in the NaCl 222 concentration and formation of products (e.g., using a ICP-OES spectrometer) and measuring pH of the effluent NaOH 232 and HC1 234 streams under steady-state operation. Results of the fourth stage 228 can include a comparison of lab-scale studies to identify an optimal electrochemical process (e.g., NF 218, RO 220, electrolyzer 230) for producing NaOH 232 and HC1 234 from the NaCl 222 stream produced after the third stage 216, utilization of NaOH 232 for the precipitation of Mg(OH)z 212 from reject brine 202 in the first stage 206 or for the production of CaCOs 214 in the second stage 208, and utilization of HC1234 to neutralize the low-TDS stream 226.214898-1863-4628Atty. Dkt. No. 046434-0978

[0080] The stages 206, 208, 216, and 228 of the system 200 form a closed-loop process where the products can be utilized as reactants to produce other minerals. For example, the NaOH 232 can be used to precipitate Mg(0H)2 212. In addition, converting the byproducts from at least two linear processes (e.g., CCS 204 and brine 202) into circular processes enables the mineral production to be energy-efficient and sustainable.

[0081] The aforementioned stages (e.g., the first stage 206, the second stage 208, the third stage 216, and the fourth stage 228) are designed to be energy and cost-efficient for mineral recovery and scalable for industrial applications. For example, brucite-based composite material 212 can be produced from the desalination brine 202 and CCS 204 waste. The recovered brucite-based composite 212 can be utilized as a construction material through direct carbonation, which results in carbon sequestration and minimizes environmental impact by eliminating the need for calcination. Additionally, the systems and methods employ an energy-efficient synthesis method, using non-commercial resources instead of high CO2 footprint chemical reagents. In addition, deploying the brucite 212 in the construction industry can have a net zero or negative environmental impact by considering CO2 sequestration during the curing and strength development stages in life cycle assessments (LCA). Brucite-based composites 212 produced using CCS 204 and reject brine 202 can have a >15 MPa compressive strength. Thus, brucite-based composites 212 can be used at least for non- structural applications with energy savings from eliminating pre-compaction.

[0082] The CaCCh 214 produced during the second stage 208 can partially replace OPC in concrete and as a constituent of the limestone calcined clay cement (LC3). A base stream 232 (e.g., NaOH solution) produced from the electrolyzer 230 (e.g., in the fourth stage 228) may be utilized to precipitate additional brucite or other industrial applications. An acid stream 234 (e.g., HC1 solution) may neutralize the high pH streams (e.g., low-TDS brine 226) before disposal or for other industrial applications. A low-TDS water stream 244 may be utilized for concrete mixing instead of freshwater.

[0083] FIG. 3 illustrates charts 300 of compression test results for compacted brucite 212 pellets carbonated under high-pressure supercritical CO2 (scCCh) conditions and a compressive strength development for compacted brucite 212 pellets under accelerated carbonation (20% CO2, 80% RH at 30°C) and ambient conditions. As shown in the charts 300, compacted pellets of brucite 212 recovered from reject brine 202 can be directly carbonated under 20% CO2 and 80% relative humidity (RH) conditions to gain rapid strength224898-1863-4628Atty. Dkt. No. 046434-0978of up to 30 MPa. The strength gain in brucite 212 synthesized using CaO is attributed to the formation of interconnected networks of particles and the formation of amorphous hydrated magnesium carbonates (HMCs) under 20% CO2 curing. The strength of the compacted brucite 212 can be further enhanced up to 38 MPa by using high-pressure supercritical CO2 (scCCh) conditions, as shown in the charts 300. Under scCCh curing conditions, high-density nesquehonite phases are formed, which may be responsible for the higher strength of the brucite pellets 212. The LCA conducted on the synthesis process of brucite 212 also confirmed that production using CaO may have a lower CO2 impact (e.g., compared to synthesis not using CaO) due to the lower CO2 emissions during commercial production of CaO compared to other alkali agents.

[0084] FIG. 4 is a chart 400 of compression test results for the compressed and uncompressed brucite 212 pellets carbonated under 20% CO2 and 80% RH at 30°C conditions. CCS 204 or acetylene waste (AW) has also been tested as a precipitation agent for the formation of brucite 212 from effluent brine 202. The obtained CCS 204 or AW powders were wet and had to be heated at 100°C for removal of excess water. The XRD and TGA analysis of the powders confirmed around -75% Ca(OH)2 content, which was used to calculate the number of powders for the reaction. The processing of the synthesized powders after the reaction was kept consistent with the processing for the results of charts 300. The synthesized brucite-based powders 212 were tested for mechanical performance under 20% CO2 conditions with samples prepared, including the pre-compaction process as well as without compaction. The samples showed compressive strength up to -22 MPa for compacted samples and up to 15 MPa for non-compacted samples as shown in the chart 400. The decrease in the strength of compacted samples can be attributed to a lower purity of the powders. The observed results confirmed that the brucite-based powders 212 can be utilized for non-structural construction applications.

[0085] FIG. 5 depicts a TGA analysis of CCS 204. The TGA analysis was performed to determine a composition of a sample of the CCS 204, specifically, a composition of the main active component, Ca(OH)2, which is responsible for precipitating magnesium from desalination reject brine 202. FIG. 5 shows that the sample of CCS contains approximately 78% Ca(OH)2 and minor amounts of CaCCh (-3.7%). Such information can then be used to calculate a ratio of CCS 204 to brine 202 for efficient magnesium recovery. For example, a234898-1863-4628Atty. Dkt. No. 046434-0978concentration of Mg in the brine 202 can be used to determine how much calcium hydroxide can be used to complete precipitation of the Mg.

[0086] For example, CCS 204 can be added to reject brine 202 at varying dosages (e.g., 10 to 13 grams per liter (g / L)) under continuous stirring. After precipitation of the magnesium, the solids (e.g., magnesium) can be washed, dried, and ground into powder. A dosage of 11 g / L was selected for optimal yield and purity of brucite 212, balancing magnesium recovery and the presence of minor calcium-containing phases like bassanite and calcite.

[0087] FIG. 6 depicts samples of the brucite 212 powders. The brucite 212 can be prepared into two types of specimens shown in FIG. 6. Specifically, the brucite 212 can be prepared into compacted pellets with a diameter of, for example, 10 millimeters (mm), to increase initial density, reduce porosity, and accelerate carbonation. The brucite 212 can be prepared into uncompacted cylinders with dimensions of, for example, 25 mm by 25 mm, to study carbonation without mechanical compaction. Both types were cured under accelerated carbonation conditions (20% CO2, 80% RH, 30 °C) for up to 30 days.

[0088] FIGS. 7-10 depict charts, a table, images of XRD, SEM, and TEM resulst. The XRD confirmed that brucite 212 is the dominant phase in the powders, with minor amounts of bassanite and calcite. Increasing CCS 204 dosage slightly increased overall yield, but reduced brucite 212 purity of the powders. SEM and TEM revealed platelet-shaped brucite particles (e.g., 20 to 80 nm) and rod-like bassanite, confirming a multiphase microstructure.

[0089] FIG. 11 illustrates a chart of compressive strength development. Compacted pellets showed rapid strength gain, reaching approximately 22 megapascals (MPa) after 144 days. Uncompacted cylinders showed slower development, reaching approximately 14 MPa after 30 days. Such difference can be due to higher density and reduced porosity in compacted samples, which enhances carbonation efficiency.

[0090] FIGS. 12-13 illustrate a thermal analysis of the samples of brucite powder 212.TG-DTG analysis revealed multiple weight-loss events corresponding to water loss from brucite and hydrated magnesium carbonate (HMC) phases, dehydroxylation and decarbonation of HMC phases, and decomposition of residual calcium carbonate. Both compacted and uncompacted samples developed amorphous and crystalline HMC phases over time, contributing to strength.244898-1863-4628Atty. Dkt. No. 046434-0978

[0091] FIGS. 14-16 illustrate the carbonate phase formation of the samples of brucite powder 212. XRD and Raman spectroscopy show progressive formation of nesquehonite, hydromagnesite / dypingite, and amorphous HMC phases. Raman band deconvolution indicated that amorphous HMC dominated early stages, gradually transforming into crystalline phases. Compacted samples favored nesquehonite formation, while uncompacted samples showed more hydromagnesite / dypingite.

[0092] FIGS. 17-19 depict SEM and TEM images showing the morphology of the samples of brucite powder 212. Specifically, the rod-like structures associated with nesquehonite, flake- or sheet-like morphologies characteristic of hydromagnesite / dypingite, and gradual densification over curing time, correlating with compressive strength trends.

[0093] FIG. 20 shows a table depicting nitrogen adsorption measurements (BET) showed a sharp decrease in surface area during carbonation, indicating matrix densification. Compacted specimens exhibited lower final surface area than uncompacted specimens, consistent with higher strength.

[0094] As shown, CCS 204 effectively precipitates brucite 212 from desalination reject brine 202, producing powders suitable for construction binders. Accelerated carbonation promotes the formation of HMC phases, densifying the matrix and increasing strength. Compaction improves early-age strength and densification, while both compacted and uncompacted specimens achieve substantial CO2 sequestration. This approach valorizes industrial waste, reduces CO2 emissions, and provides a sustainable alternative to conventional cements.

[0095] The system 200 described above details the recovery of four major minerals -brucite (Mg(OH)2) 212, CaCCh 214, NaOH 232, and HC1 234 - from effluent brine 202 by combining reactive crystallization, mineralization, NF 218, RO 220 as well as electrolysis strategies. These methods effectively remove the most abundant ions in reject brine 202, namely, Mg2+, Ca2+, Na+, and Cl". The process 200 not only facilitates the mining of minerals from desalination waste but also controls the salinity of the brine discharge. Since the system 200 can be carried out at room temperature, any adverse impact on the marine ecosystem can also be reduced. Also, since calcium carbide residue is used for the extraction of brucite 212, the system 200 also contributes to reducing the waste from acetylene production. The chemical mineralization steps also help minimize energy demand in comparison to energy-254898-1863-4628Atty. Dkt. No. 046434-0978intensive hydrolysis. Seeded reactive crystallization may be adopted through partial recirculation of the precipitate solutions (e.g., brucite 212 and calcium carbonate 214) back into the respective reactors. Using mineralization and recirculation of precipitation solution reduces the overall critical super-saturation limit, thus improving the reaction rate and crystal growth for better control of particle size distribution.

[0096] The recovered brucite and CaCCh both have applications in the construction industry as potential alternatives to OPC. Compared to the production of MgO from the calcination of MgCCh, the calcination energy and CO2 released from the chemical decomposition of MgCCh can be eliminated in the system 200. In addition, the brucite 212 can be directly carbonated to strengthen the composite. The brucite 212 can have a compressive strength >15 MPa, indicating that the brucite 212 can be directly used in non-structural applications in construction and using brucite 212 eliminates the need for calcination and the associated energy consumption.

[0097] The system 200 can also include a CO2 mineralization-based approach to produce Na2CCh 211 from NaOH 232 to recover CaCCh 214. Mineralization-based CO2 capture and storage involve inherently lower energy processes since CO2 capture and storage occur without a separate removal or concentration step (e.g., absorption from a vapor phase). These processes also utilize the thermodynamics of carbonate precipitation reactions. Mineralization-based approaches can be applied across a wide range of CO2 concentrations (e.g., atmospheric concentrations to 100 vol. % CO2) and temperatures (e.g., ambient to ~90°C) without increasing energy expenditure and are also insensitive to the impurities in CCh-containing streams (e.g., hydrocarbons and H2S). Thus, mineralization approaches allow for simple, flexible, and modular (e.g., few unit operations) strategies for CO2 capture and emission mitigation in the oil and gas sector.

[0098] The amount of cement to be replaced and carbon sequestration potential may contribute to carbon footprint reduction for the construction industry. The direct carbonation of the recovered brucite 212 for building applications is also associated with a considerably lower carbon footprint as compared to that of RMC obtained from the calcination of magnesite, considering the elimination of grinding, calcination, and absence of chemical decomposition in the reject brine route. A life cycle assessment (LCA) performed previously indicated that alkalis may be the highest contributors to CO2 emissions during the production of synthetic MgO. However, brucite 212 recovered from reject brine 202 using CaO produces264898-1863-4628Atty. Dkt. No. 046434-097828.8-37.1% less CO2 eq. emissions compared to commercial MgO produced from MgCCh. Since the process 200 replaces CaO with CCS 204, a waste from the acetylene industry, the CO2 emissions during the synthesis of Mg(OH)2212 can be further reduced.

[0099] The system 200 can implement a mineral recovery process, such as the process 100, to extract Mg(OH)2212, CaCCh 214, NaOH 232, and HC1 234 which means a closed-loop operation where CaO can be obtained from the first stage 206 through calcination with renewable energy sources and fed into the second stage 208 for Mg(OH)2212 precipitation. Furthermore, the NaOH 232 recovered at the end of the third stage 216 can also be used in the extraction of the Mg(OH)2212 in the first stage 206 and for the production of the Na2COs 211 stream for CaCOs 214 recovery in the second stage 208. These processes ensure the recovery is closed loop, and additional precipitating agents may not be needed.

[0100] The geographical limitation of MgCCh reserves used to produce RMC can also be overcome with the use of concentrated reject brine 202 as raw feeds in the synthesis of reactive brucite 212 and thus help to increase the accessibility of the material in regions where desalination has been the main source of potable water.

[0101] The system 200 is designed to be independent and modular, thus implementing minimal changes to existing desalination plants. The water used for washing the precipitates can also be obtained at the end of the NF 218 and RO 220 step, thereby also reducing piping and connection used to circulate the water. Natural drying under the sun can be done off-site next to the plant to minimize the cost and environmental impacts of transportation. Further, the process 200 aims to utilize the recovered minerals, Mg(0H)2 212 and CaCOs 214, as binders in composite building materials, while NaOH 232 and HC1 234 enhance the use for the rejected brine 202. Utilizing the brucite 212 and CaCOs 214 in precast products (e.g., cement) may result in time and workforce savings as well as an increase in the productivity and safety of the construction industry.

[0102] FIG. 21 is a flow diagram of an example method 2100, according to some embodiments of the present disclosure. The method 2100 can include, at block 2102, mixing a first byproduct (e.g., CCS, CCS 204, first byproduct 1021) and a second byproduct (e.g., reject brine, high-salinity brine, brine 202, second byproduct 104) to form a first compound (e.g., Mg(0H)2, Mg(OH)2212, first compound 110) and a first reduced byproduct (e.g., brine without Mg, brine 236, first reduced byproduct 114). The second byproduct may have274898-1863-4628Atty. Dkt. No. 046434-0978concentrations of Na+, Cl", Mg2+, and Ca2+ions at around 19900 parts per million (ppm), 36270 ppm, 2220 ppm, and 1080 ppm, respectively. The second byproduct can be filtered to remove particulate impurities prior to being mixed with the second byproduct. The first byproduct may be stored in a storage tank and mixed with the second byproduct in a precipitation reactor (e.g., first reactor, reactor 210) to form the first compound.

[0103] In some implementations, the first byproduct and the second byproduct are mixed at room temperature to form the first compound. The first compound can precipitate from the reaction of the first byproduct with the second byproduct. The first byproduct may include Ca(OH)2 and CaCCh as well as carbon and silicate. The first byproduct can be dried to remove excess water prior to being mixed with the first byproduct. The first byproduct may be a byproduct of acetylene production and the second byproduct may be a byproduct of desalination.

[0104] In some implementations, NaOH (e.g., NaOH 232, third substance, third substance 122) is also replaced with the first byproduct and the second byproduct to form the first compound. The first compound can be washed and dried following formation in the precipitation reactor. The first byproduct and the second byproduct may be mixed at a constant rate at room temperature. The first compound may be a brucite powder. The first reduced byproduct may be stored in a storage tank. Both the first compound and the first reduced byproduct may be reaction products of the first byproduct and the second byproduct. The first reduced byproduct is the second byproduct without magnesium, which is precipitated out after being mixed with the first byproduct.

[0105] In some implementations, the precipitation reactor has a volume of about 120 liters. The precipitation reactor can be made of acrylic with an agitator. The agitator can be rotated using a power supply to mix the reactants (e.g., the first byproduct and the second byproduct). Slurry (e.g., solid dissolved in liquid) and peristaltic pumps can flow the reactants into the precipitation reactor at fixed flow rates. The temperature and pH can be measured while the reactants are being mixed.

[0106] At block 2104, a second compound (e.g., Na2CCh, Na2CCh 211) is mixed with the first reduced byproduct to form a third compound (e.g., CaCCh, CaCCh 214, third compound 112) and a second reduced byproduct (e.g., brine without magnesium or calcium, brine 238, second reduced byproduct 116). The second compound can be an alkali, such as Na2CCh. The284898-1863-4628Atty. Dkt. No. 046434-0978second compound can be a precipitation agent. The second compound can be mixed with the first reduced byproduct at a constant rate at room temperature. The third compound may be formed in a precipitation reactor (e.g., second reactor) and washed and dried. The second reduced byproduct can be stored in a storage tank. The second reduced byproduct is the second byproduct without magnesium or calcium, which are both precipitated out to form the first compound and the third compound. For example, the third compound is precipitated out from a reaction between the second compound and the first reduced byproduct which also forms the second reduced byproduct.

[0107] At block 2106, the second reduced byproduct is converted into a first substance (e.g., NaCl, NaCl 222, first substance 118) and a second substance (e.g., freshwater and low-TDS brine, fifth substance 126 and sixth substance 128, freshwater 224 and low-TDS brine 226, multivalent ion stream 242, second substance 120). Following the first byproduct being mixed with the second compound to form the first reduced byproduct, and the first reduced byproduct being mixed with a second compound to form the second reduced byproduct, the second reduced byproduct may be free of Mg and Ca due to the Mg and Ca being precipitated out to form the first compound and the third compound. The second reduced byproduct can be converted into the first substance and the second substance via separation by a plurality of membranes. For example, the plurality of membranes (e.g., membranes 219) can be used to perform NF (e.g., NF 218) to separate and convert the second reduced byproduct into the first substance and the second substance. For example, the second reduced byproduct can undergo NF to produce the first substance, which includes NaCl, and the second substance which includes multivalent streams (e.g., liquids with positively and negatively charged ions, multivalent stream 242). The second substance can include freshwater and low-total dissolved solids (TDS) brine. For the second substance to split into a fifth substance (e.g., freshwater, fifth substance 126) and the sixth substance (e.g., low-TDS brine, sixth substance 128), respectively, the second substance can undergo RO (e.g., RO 220) via at least a portion of the plurality of membranes. The first substance may be a stream of NaCl. Each of the first substance and the second substance may be stored in a storage tank (e.g., storage tank 209).

[0108] At block 2108, the first substance can be converted into a third substance (e.g., NaOH, NaOH 232, third substance 122) and a fourth substance (e.g., HC1, HC1 234, fourth substance 124) via an electrolyzer performing an electrolysis process. The third substance can be NaOH, and the fourth substance can be HC1. Following electrolysis (e.g., by electrolyzer294898-1863-4628Atty. Dkt. No. 046434-0978230), both the third substance and the fourth substance can be stored in respective storage tanks. The fourth substance can be mixed using a mixer (e.g., mixer 240) with the low-TDS brine of the second substance to neutralize the low-TDS brine (e.g., neutralized sixth substance, neutralized sixth substance 244, sixth substance 226). The third substance can be mixed with the second byproduct prior to being mixed with the first byproduct at block 2102.

[0109] FIG. 22 is a flow diagram of an example method 2200, according to some embodiments of the present disclosure. At block 2202, the method 2200 can include precipitating a first compound by reacting a first byproduct including at least one calcium compound and a second byproduct including magnesium, where the reaction of the first byproduct and the second byproduct forms a first reduced byproduct. For example, Mg(0H)2 can be precipitated out from a reaction of reject brine and CCS in a precipitation reactor. In some implementations, the first compound can be precipitated out from a reaction between the reject brine and CCS performed at room temperature.

[0110] At block 2204, the method 2200 can include precipitating a third compound by reacting a second compound and the first reduced byproduct, where the reaction of the second compound and the first reduced byproduct forms a second reduced byproduct. For example, CaCCh can be precipitated out from a reaction between Na2CCh and brine without magnesium. In some implementations, the third compound can be precipitated out from a reaction between the Na2CCh and the brine without magnesium performed at room temperature.[OHl] At block 2206, the method 2200 can include separating the second reduced byproduct into a plurality of substances. The second reduced byproduct can be the input reject brine without magnesium or calcium. Separating the second reduced byproduct can include separating, by NF, the second reduced byproduct into a first substance and a second substance. The first substance can include NaCl, and the second substance (e.g., multivalent ion stream) can include freshwater and low-TDS brine. The first substance can be separated by electrolysis into a third substance and a fourth substance. The third substance can be NaOH and the fourth substance can be HC1. The second substance can be separated into a fifth substance and a sixth substance by RO. The fifth substance can be freshwater and the sixth substance can be low-TDS brine. NF and RO can use at least one membrane to separate the respective substances.304898-1863-4628Atty. Dkt. No. 046434-0978Definitions.

[0112] As used herein, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, the term “a member” is intended to mean a single member or a combination of members, “a material” is intended to mean one or more materials, or a combination thereof.

[0113] As used herein, the terms “about” and “approximately” generally mean plus or minus 10% of the stated value. For example, about 0.5 would include 0.45 and 0.55, about 10 would include 9 to 11, about 1000 would include 900 to 1100.

[0114] It should be noted that the term “exemplary” as used herein to describe various embodiments is intended to indicate that such embodiments are possible examples, representations, and / or illustrations of possible embodiments (and such term is not intended to connote that such embodiments are necessarily extraordinary or superlative examples).

[0115] As used herein, the terms “coupled,” “connected,” and the like mean the joining of two additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate members being attached to one another.

[0116] It is important to note that the construction and arrangement of the various exemplary embodiments are illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter described herein. Other substitutions, modifications, changes and omissions may also be made in the design, operating conditions and arrangement of the various exemplary embodiments without departing from the scope of the present invention.

[0117] While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any inventions or of what may be claimed, but rather as descriptions of features specific to particular implementations of particular inventions. Certain features described in this specification in the context of separate314898-1863-4628Atty. Dkt. No. 046434-0978implementations can also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.324898-1863-4628

Claims

Atty. Dkt. No. 046434-0978WHAT IS CLAIMED IS:

1. A method, comprising:mixing a first byproduct comprising at least one calcium compound and a second byproduct comprising magnesium to form a first compound and a first reduced byproduct formed from a reaction between the at least one calcium compound and the magnesium; mixing a second compound and the first reduced byproduct to form a third compound and a second reduced byproduct formed from a reaction between the at least one calcium compound and the second compound;converting, by nanofiltration, the second reduced byproduct into at least a first substance and a second substance; andconverting, by electrolysis, the first substance into a third substance and a fourth substance.

2. The method of claim 1, wherein:the first byproduct comprises calcium carbide slag (CCS), andthe second byproduct comprises brine.

3. The method of claim 1, wherein:the at least one calcium compound comprises calcium hydroxide (Ca(OH)2), and the first compound comprises Mg(0H)2.

4. The method of claim 1, wherein the second compound comprises Na2CO3.

5. The method of claim 1, wherein the first substance comprises NaCl.

6. The method of claim 1, wherein:the third substance comprises sodium hydroxide (NaOH), andthe fourth substance comprises hydrochloric acid (HC1).

7. The method of claim 1, wherein the first byproduct and the second byproduct are mixed at room temperature to form the first compound.

8. The method of claim 1, wherein:the second compound comprises an alkali, andthe third compound comprises CaCCh.334898-1863-4628Atty. Dkt. No. 046434-09789. The method of claim 1, wherein:the first byproduct is a byproduct of desalination, andthe second byproduct is a byproduct of acetylene production.

10. The method of claim 1, wherein:the first reduced byproduct is the second byproduct without the magnesium, and the second reduced byproduct is the second byproduct without the magnesium and calcium.

11. The method of claim 1, further comprising converting, by reverse osmosis, the second substance into a fifth substance and a sixth substance, the fifth substance being freshwater and the sixth substance being low-total dissolved solids (TDS) brine, wherein the second substance comprises a multivalent ion stream.

12. The method of claim 11, further comprising mixing the fourth substance with the sixth substance to form a neutralized sixth substance.

13. The method of claim 1, wherein the third substance is mixed with the first byproduct and the second byproduct to form the first compound and the first reduced byproduct.

14. A system, comprising:a first reactor configured to mix a first byproduct comprising at least one calcium compound and a second byproduct comprising magnesium to form a first compound and a first reduced byproduct;a second reactor configured to mix a second compound and the first reduced byproduct to form a third compound and a second reduced byproduct;a plurality of membranes configured to separate the second reduced byproduct into at least a first substance and a second substance; andan electrolyzer configured to convert the first substance into a third substance and a fourth substance.

15. The system of claim 14, wherein the second reduced byproduct is separated into the at least the first substance and the second substance by nanofiltration.

16. The system of claim 14, wherein the first reactor and the second reactor are precipitation reactors.344898-1863-4628Atty. Dkt. No. 046434-097817. The system of claim 14, further comprising a mixer configured to mix the fourth substance and a portion of the second substance to form a neutralized sixth substance.

18. A method, comprising:precipitating a first compound by reacting a first byproduct comprising at least one calcium compound and a second byproduct comprising magnesium, wherein reaction of the first byproduct and the second byproduct forms a first reduced byproduct;precipitating a third compound by reacting a second compound and the first reduced byproduct, wherein the reaction of the second compound and the first reduced byproduct forms a second reduced byproduct; andseparating the second reduced byproduct into a plurality of substances.

19. The method of claim 18, further comprising:separating, by nanofiltration, the second reduced byproduct into a first substance and a second substance;separating, by electrolysis, the first substance into a third substance and a fourth substance; andseparating, by reverse osmosis, the second substance into a fifth substance and a sixth substance.

20. The method of claim 19, wherein the first substance comprises sodium chloride (NaCl), the second substance comprises freshwater and low-total dissolved solids (TDS) brine, the third substance comprises sodium hydroxide (NaOH), the fourth substance comprises hydrochloric acid (HC1), the fifth substance comprises freshwater, and the sixth substance comprises low- TDS brine.354898-1863-4628

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