Expanded clay incorporated with carbonate-based salts with fire-suppressing capacity for application as a fire retardant in confined spaces.

Description

1 / 25 Expanded clay incorporated with carbonate-based salts with fire-suppressing capacity for application as a fire retardant in confined spaces. TECHNICAL FIELD OF THE INVENTION

[0001] This document discusses the development of a low-cost and easy-to-install device, produced from expanded clays (lightweight aggregates) of varying sizes, whole or crushed, modified by the incorporation of carbonate-based salts or salts with fire-suppressing capacity into its porous interior and surface. Furthermore, it describes the use of this device as a fire extinguishing or inhibiting agent in confined spaces, capable of being activated upon contact with fire. Its mechanism of action, for carbonate-based salts, occurs through the release of CO2, preventing heat conduction to the polymeric components of the meter; for fire-suppressing salts, via mechanisms that capture radicals that propagate flames. STATE OF THE ART

[0002] Recently, armored meter boxes have been installed to replace traditional energy meters, aiming to reduce fraud in the energy distribution system. Since the installation of the armored boxes, there has been a reduction of approximately 40% in energy theft in the installation regions. Frequent attempts to disable the armored boxes have begun to emerge, the most effective being the propagation of fire through the conductor cables. Such damage to the boxes and cables has created new types of significant losses for energy distributors. Furthermore, these actions occur in various locations and at any time, making them difficult to predict. Therefore, the demand arises for a fire inhibition or extinguishing system that is internal to the meter box, preserving its electrical components. Petition 870240109851, dated 12 / 23 / 2024, page 15 / 45 2 / 25

[0003] According to prior art research, it was found that a very wide range of chemical compounds are used, alone or in combination, to obtain suppressive or retardant action. Therefore, the objective of the invention was to combine materials or substances that would meet the required demand and, in addition, be quick and easy to produce from basic and readily available materials. Furthermore, they should allow for easy installation and handling, since the shielded metering boxes are located on top of public lighting poles and in very unhealthy working areas for the operator (Figure 1). In addition to controlling the flames, they should inhibit thermal conduction inside the confined environment. Electronic components containing thermoplastic material, which undergo crystalline fusion, can deform due to heat and may drip, thus fueling the flames.In general, these plastics are highly flammable polyolefins (1). In contrast to this characteristic, ceramic materials are known to be excellent thermal insulators, and among them, clay minerals (2). Following this line of reasoning, the suggested combination consists of a support, which are Light Expanded Clay Aggregates (LECAs), modified by incorporating a suppressant / retardant into their porous internal structure and surface. In this work, the incorporation was preferably done with carbonate-based salts. This incorporation occurs through the immersion of the LECAs in a saline bath, i.e., a high concentration solution of the salt of interest, in a controlled pH range.

[0004] As is already known, the main component of fire extinguishers used to fight fires involving electrical equipment or flammable liquids is carbon dioxide, CO2. This is because it is a non-conductive gas and because the residue left by it does not damage electrical components (3). Devices capable of releasing gas Petition 870240109851, dated 12 / 23 / 2024, page 16 / 45 3 / 25 carbon dioxide and eliminating oxygen gas to reduce flame propagation are of interest for use inside armored boxes.

[0005] An efficient way to produce CO2, also used for fire fighting, is from the thermal decomposition of carbonate salts. Bicarbonates decompose between 100 and 200 °C and form carbonates, which in turn only decompose at temperatures above 800 °C (4), shown in equations 1 and 2. KHCO3(«,) K-CO..„.'H:O1CO2(g) (1)K2CO·....- K2O(s)+ CO2(g)(2)

[0006] For bicarbonate, CO2 release occurs shortly after contact with the flame, meaning it is a rapid response to heating. For carbonate, however, the release is slower due to the need for a higher temperature. Therefore, combining the two types of salts in a single device can result in variations in the response time of CO2 release. Furthermore, when the salts are in solution, controlling the pH of the saline baths allows for balancing the concentrations of bicarbonate and carbonate, thus enabling control over the quantity of both salts. Therefore, controlling the quantity of salts would promote CO2 generation at different times when the mixture is in contact with the flame.

[0007] The study and production of baths using other salts with fire suppression capacity has not yet been applied to incorporation into LECAs. However, the potential is already visible, since it is sufficient that these salts have good solubility in water. The ability of some metals to act as scavengers of radicals that propagate flames is already widely known (5) (6), thus opening a field for the study of these mechanisms in confined spaces and forms of quality control.

[0008] Lightweight Expanded Clays, or LECAs (from the English light expanded clay aggregate), have porous internal structures and can be Petition 870240109851, dated 12 / 23 / 2024, page 17 / 45 4 / 25 defined as “the product obtained by heating some types of clay at a temperature around 1200 °C” (7). Chemically, LECAs are composed of hydrated silicates of aluminum, iron and magnesium, consisting of crystalline particles, and may contain a certain amount of alkali and alkaline earth metals, organic materials, soluble salts and particles of other minerals, as well as non-crystalline or amorphous minerals (8). The obtaining of its porous structure occurs because, near this high temperature, part of the compounds present in the clay material melt, while another part decomposes chemically. This then releases gases that become incorporated into the sintered mass, expanding it up to seven times its initial volume. As the gases do not escape due to the phase that melted, the porous structure is maintained after cooling (7). Figure 2 shows the internal structure of LECAs, as well as their surface.Several academic works are dedicated to the characterization of these aggregates, such as ZUKRI et al (2018) (9), MORAVIA et al (2006) (7), RASHAD et al (2018) (10), BODNÁROVÁ et al (2014) (11), KILINÇ et al (2008) (12), SANTOS et al (2018) (13). These studies focus on gathering information on their physical-chemical, granulometric, and mechanical properties, mainly due to their applications in the civil construction industry as aggregate for concrete. LECAs provide some interesting characteristics, as they are an inert material with great acoustic and thermal insulation capacity, providing a decrease in density and an increase in water absorption when associated with concrete. BACKGROUND OF THE INVENTION

[0009] According to the literature, fire suppressants or inhibitors are produced from mixtures of chemical compounds, as reported in the following documents: BR 10 2023 017944 4 A2(14), which describes the production of so-called oxygen-encapsulating agents, using phosphate products, such as phosphoric ester, monoethanolamine phosphate; Petition 870240109851, dated 12 / 23 / 2024, page 18 / 45 5 / 25 suppressants employing azeotropic mixtures with Z-1,1,1,4,4,4-hexafluoro-2-butene, trans-1,2-dichloroethylene and 1,1,1,3,3-pentafluorobutane in the preparation of thermoplastic and thermosetting foams, as described in invention BR20121116979 20110110 (15); invention PI 0500548-5 B1 (16), in which a mixture comprising water, a highly concentrated alkali and at least one of a combination of anhydrous citric acid, citric acid, acetic acid or a salt correlated thereto is used. The composition also includes phosphate, alkali metal salt in combination with acetate, bicarbonate, carbonate and / or hydroxide. For applications in electrical devices, it is of fundamental importance to use materials that do not accelerate corrosive processes, as can occur with highly hygroscopic salts, such as phosphates. The presence of water in confined environments, such as the interior of metering boxes, is also undesirable.These issues make the use of the technological solutions cited in documents BR 10 2023 017944 4 A2 and PI 0500548-5 B1 unfeasible. Furthermore, the presence of flammable plastics, such as polyurethanes, should also be avoided in the desired technology.

[0010] Many inventions have in their compositions minerals or clays, as described in BR20211123298 20200522 (17), with application in wire coating or passive fire resistance, having as composition alkaline earth carbonate, kaolin and magnesium hydroxide, and may also include ethylene-vinyl acetate, polyethylene and dicumyl peroxide. In invention BR 11 2020 021041 2 A2 (18) the use of additivated foams is also shown, comprising surfactants and / or hydrotropes, particulate inorganic materials of perlite, talc, calcium carbonate, kaolin, dolomite, mica and bentonite, as well as their combinations, and, optionally, one or more additives. In addition, nanostructured products, such as in invention BR102014030429B1(19), consisting of modified nanoclay, phosphorus salt and hydrophilic polymer are described in the technical and scientific literature. In this case, the nanoclay is dispersed in an aqueous medium, followed by the addition of phosphate salt and the Petition 870240109851, dated 12 / 23 / 2024, page 19 / 45 6 / 25 incorporation of hydrophilic polymer, and used as an additive for materials, mainly polymeric. Finally, the description of fire protection mortar comprising binder cement, calcite, mica, xonotlite, expanded perlite, fibers, in addition to an air-entraining and foam-forming agent, described in invention BR102014002644A2 (20).

[0011] Other technologies are based on the construction of physical barriers, many of them using LECAs as a base. Invention WO / 2014 / 209140 (21) describes the production of molded panels for use in civil construction, sandwich type, with a core composition of magnesium oxide, perlite (hydrophobic), magnesium chloride, among other varied components. The external coatings are made of magnesium oxychloride, gypsum, metal or fiber blanket. Invention BR 11 2023 018332 4 A2 (22) reports a multi-layered thermal barrier material, including at least one insulating layer, a compressible cushion and one or more layers that have favorable heat dissipation properties, together with a module or battery pack. In invention PI 9901624-9 A2 (23) expanded clay is used directly as insulation and a thermal barrier, alone or in conjunction with an adequate volume of water through the use of hoses.This background reveals the use of a very wide range of chemical compounds in combination for the production of the suppressant or retardant. These combinations make the production process complex and expensive, which is often not offset by the gain in efficiency.

[0012] In addition to these documents, the academic literature also provides countless articles on evaluating the effectiveness of various types of substances, applying them as suppressants. Since the establishment of the Montreal Protocol in 1989, which banned the use of suppressants based on Halon 1301 (Bromotrifluoromethane, CF3Br), the need for the discovery of "clean" suppressants and Petition 870240109851, dated 12 / 23 / 2024, page 20 / 45 7 / 25 simultaneously efficient, shot up (24). New and already known compounds with suppressive capacity were once again studied, and, to this day, several works are still being published in this area. For example, sodium bicarbonate (NaHCO3) was already being studied as a suppressor of explosions in grain silos before the establishment of the Montreal Protocol (25)(26) and was immediately resumed in post-event research, being studied until recent years (27-31). Of note are the research with inert gases (32), with the mineral struvite, both in synthetic form and recovered from wastewater (33-36); Chlorides, mainly of alkali metals (6,37), halogenated organic compounds with low boiling point (38,39), zeolites (40), and, in more recent research, Dry Water (41-44), hydrogel (45) and ecological retardants, such as banana pseudostem sap, obtained from agricultural waste (46,47).

[0013] Because the prior art search did not find results for products similar to the invention described herein, we can say that its advantages include: i) low production cost, due to the use of few steps and simple, commercially available products for manufacturing; ii) ease of incorporating carbonate salts into the internal structure of LECAs; iii) ease of installation in confined spaces; iv) replacement of activated clays with new ones; v) the possibility of reusing the structures for further modifications; and vi) ease of treating the generated waste. OBJECTIVES OF THE INVENTION

[0014] The objective of the invention was to combine materials or substances that would meet the required demand, and, in addition, that would be quick and simple to produce, from basic and readily available materials. Furthermore, they should allow for easy installation and handling, since the armored metering boxes are located on top of public lighting poles and in very unhealthy working areas. Petition 870240109851, dated 12 / 23 / 2024, page 21 / 45 8 / 25 for the operator. Which, in addition to controlling the flames, would inhibit thermal conduction inside the confined space. BRIEF DESCRIPTION OF THE INVENTION

[0015] The solution described in this document is based on the development of an apparatus composed of a clay mineral support, which are lightweight expanded clays (LECAs), modified by incorporating into its porous internal structure and surface, preferably with carbonate-based salts, more preferably with carbonates and bicarbonates, even more preferably with bicarbonates. This incorporation is done by immersing the clays in a saturated or supersaturated solution of the salts. These salts can be replaced by other compounds that have good solubility and flame-retardant characteristics. DETAILED DESCRIPTION OF THE INVENTION

[0016] The developed apparatus consists of expanded clays (lightweight aggregates), applied as a fire retardant in confined environments, characterized by containing lightweight expanded clays incorporated with bicarbonate at a concentration of 85 to 100% w / w and carbonate at a concentration of 0 to 15% w / w, with a pH between 8.5 and 12.0 in which the bicarbonate concentration is at least 85%. These salts remain incorporated after the drying process of the expanded clays.

[0017] Furthermore, LECAs have varying sizes, whole or crushed, modified by the incorporation into their porous interior and surface, preferably of carbonate-based salts or other salts that have good solubility and retardant action. LECAs must be washed to remove dirt and release the pores. Then, incorporation occurs by immersing them for 4 hours in a saline bath, that is, a solution of known concentration of the salt of interest. For alkaline baths, pH control must be performed. Petition 870240109851, dated 12 / 23 / 2024, page 22 / 45 9 / 25 which can vary between 8.0 and 12.0. Preferably, the solution should be kept at rest, without agitation. pH measurement should be performed using conventional techniques, using a pH meter or pH indicators. These baths can be made in polyethylene tanks or drums, or polypropylene containers in the case of alkaline baths, given the incompatibility of alkaline solutions with glass containers. A 1:1 volume ratio (one volume of LECA to one volume of solution) is preferred and ensures the deposition of salt on the clay. After the immersion period, the clays, already incorporated with the salt, are air-dried and subsequently packaged. The entire LECA production process takes place at room temperature. After the complete process, the LECAs are stored in plastic packaging.

[0018] To validate the presence of bicarbonate / carbonate and incorporation efficiency, samples of the modified LECAs are collected, crushed, and homogenized. These samples are then treated with concentrated hydrochloric acid in a sealed vial, where carbon dioxide (CO2) is released into the headspace. The generated CO2 is collected with a syringe and analyzed by gas chromatography (GC) using a barrier discharge ionization (BID) detector. The CO2 concentration quantifies the release and confirms the incorporation of the carbonates. For use, they are placed inside the shielded box, as shown in Figure 3. If a heat source is placed near the cable entry opening, as shown in Figure 4, the heating causes the carbonates to decompose, forming gaseous carbon dioxide inside.Thus, in addition to the naturally insulating properties of LECAs, the incorporation of carbonates allows for a combined action with the gas to retard the fire inside the box. These characteristics, combined with the ability of some salts to generate carbon dioxide (CO2) after heating and degradation, make LECAs the ideal medium for this purpose. Details regarding quantities used, dissolution time, and heating will depend on the specific requirements. Petition 870240109851, dated 12 / 23 / 2024, page 23 / 45 10 / 25 properties of the salts (or mixtures of salts) selected to compose the bath.

[0019] The absorption / adsorption of salts to the porous structure and surface of LECAs can occur through two processes. The first is based on the characteristic of LECAs, as clay minerals, which have the capacity to perform ion exchange. They have ions fixed both on their surface and between the layers and within the channels of their crystalline structure. These ions can be exchanged for other ions in aqueous solution, through chemical reactions, and these interactions / reactions do not modify the crystalline structure itself. These exchangeable ions can interfere with their physical-chemical characteristics and properties as well as technological ones(8). Another process would be purely physical, in which the solution, upon penetrating the internal and porous structure of the LECA, simply deposits inside the pore. It has not yet been possible to determine which of the two processes is predominant; however, this characteristic does not compromise the understanding of the apparatus's mechanism of action.On the other hand, after the bath, it was possible to detect the increase in mass, the saline structures within the LECAs by scanning electron microscopy (SEM), in addition to the detection of the CO2 signal during gas chromatography (GC) analysis, as shown in the chromatogram shown in Figure 5.

[0020] An important step in the development of modified clays was the study of chemical equilibria between the species present in saline baths. This knowledge allowed the optimization of the baths, initially with the aim of obtaining the greatest possible amount of bicarbonate aggregates per gram of LECAs. The main equilibria to be considered are shown in equations 3 to 9 (48). Equation 3 represents the case of the production of the saline bath from the dissolution of potassium carbonate. Due to the equilibrium established between the carbonate anion and water (equation 4), bicarbonate and carbonic acid species are formed in the medium (equations 5 and 6), the solution acquiring a basic pH at the end of the dissolution varying between 11 and 12. The acid Petition 870240109851, dated 12 / 23 / 2024, page 24 / 45 11 / 25 The carbon dioxide generated is an unstable species that degrades into carbon dioxide and water (equation 7), while the opposite also occurs, the gas comes into equilibrium again with water, generating carbonic acid, bicarbonate and carbonate. K. CO:. 2 k-...:+co 3r: HO(l) -HO / . +OH(aq)(4)CO3-(aq)+H3O+aq)—HCO·.+ H2O(l) HCO· ..+HO / ...- H.CO^q, + H2O(0 H.CO3(sq) - CO2(a) + H2OW(7) KHCO.. K / q-HCO (aq)(8) HCO3(aq)+H3O+aq)- ^CO^ + ^OffiH C°... -CO2(g) + H2O(7)HCO3«q)+ H2O(l)— CO2-(aq)+H3O+aq)

[0021] For the saline bath produced with potassium bicarbonate salt (equation 8), the same equilibria are obtained, but the final pH is around 8.5. In this case, carbonate is also formed in the medium (equation 9). Here, the direct dependence of pH on the establishment of the fractions present in solution of each of the species involved is highlighted, which can be seen in Figure 3. Thus, in the case of the saline bath produced with potassium carbonate, with a pH between 11 and 12, we will have predominantly carbonate present, about 85%. In the bath produced from potassium bicarbonate, with an approximate pH of 8.5, we will have a bicarbonate fraction greater than 90%, which is desirable for incorporation into LECAs for rapid response. Therefore, in the case of using potassium carbonate salt for the purpose of producing bicarbonate for rapid response, there must be an extra step of adjusting the pH to 8.5. Petition 870240109851, dated 12 / 23 / 2024, page 25 / 45 12 / 25

[0022] To obtain different fractions of the species in the saline bath, the pH must be adjusted according to the required fraction. The calculations of the fractions (equations 13, 14 and 15) can be deduced from the pH value (equation 11), mass balance (equation 12), charge balance (18) (considering hydrochloric acid for pH adjustment) and the law of mass action of this system (equations 13 and 14). In addition, tabulated information on pKa values ​​(negative logarithm of the acidity constant, Ka, equation 10) is also used, with the first pKa1 being equal to 6.35 (relative to the carbonic acid deprotonation equation) and the second pKa2 being equal to 10.33 (relative to the bicarbonate deprotonation)(49). Ka=10-pKa (10) [H3O+]=10-pH c(CO-32)=[H2CO3 ] + [CO32]+[HCO3] _[HCO3 ]·[Η3θ+] a1 [H2CO3] [<:°:|[η()·| 2 [HCO3] [H2CO3] [H2CO3] «0= = c(CO32) [H2CO3]+[CO32]+[HCO3] [HCO-3] [HCO-3] «1 =-----= =-------------Z-------- c(CO32) [H2CO3]+[CO32]+[HCO3] .. _ [CO32] _ [CO32] «2 , Ok .-o-. c(CO32) [H2CO3]+[CO32]+[HCO3] [Cl-]=-[HCO3]-2[CO32]-[OH-]+2[K+]+[H3O+] (11) (12) (13) (14) (15) (16) (17) (18)

[0023] To obtain the values ​​of the fractions of carbonic acid ( «0, equation 21), bicarbonate ( «1, equation 22) and carbonate ( «2, equation 23) solely as a function of pH and pKa values: Petition 870240109851, dated 12 / 23 / 2024, p. 26 / 45 13 / 25 Kai [HCO3] 10-PH [H2CO3] (19) „Ka2[CO32]-10-PH(20) - r\-pKa2_ L3J = [HCO3]a=_______________1 (a0 i+ioPH-PKa1+io2pH-Pka1-PKa2a=1(22)11+10Pka1-PH + 10PH-Pka2 ^2 = 1-(^1+^0)(23)

[0024] In this way, it is possible to calculate the quantities and concentrations of both the saline bath and the hydrochloric acid to be used in pH adjustments.

[0025] However, an unavoidable problem arising from the acidification of the saline bath using a strong acid is the buffer effect. This can be described as a “protective effect against abrupt changes in the acidity or basicity of the solution”, that is, solutions that resist variations in the concentration of acid added to the medium. Generally, they can be obtained when solutions of a weak acid with its conjugate base (salt), or of a weak base with its conjugate acid (salt), at a pH close to the pKa of the acid (50). What happens is that, in the reaction shown in equation 5, we have a weak base, carbonate, and its conjugate acid, bicarbonate; while in equation 6, bicarbonate acts as the conjugate base of the weak acid, which is carbonic acid. We therefore have two different equilibria to take into account in the case of the saline bath, and two different pKas.The buffer begins to act when a strong acid is added to the solution, which is precisely the case with the addition of hydrochloric acid during the pH adjustment of the bath. A larger volume than expected is needed to "break" the buffer effect. In practice, this leads us to have to use a larger quantity of acid, and consequently, a greater final dilution of the saline bath, in addition to a higher cost for the acid. This... Petition 870240109851, dated 12 / 23 / 2024, page 27 / 45 14 / 25 The problem limits the use of a very high concentration for the pH-adjusted saline bath, since the buffering power increases directly proportionally to the concentration. This problem would not occur in the case of the saline bath prepared with potassium bicarbonate salt, since the final pH after dissolution is already at the pH that maximizes a greater fraction of bicarbonate. A second issue that arises as a consequence of pH adjustment is the probable formation of a second salt in the medium, potassium chloride. This salt will probably be incorporated along with the carbonated salts, which can generate a "competition," decreasing the actual aggregate mass of carbonated salt. Again, for the saline bath prepared with potassium bicarbonate salt, this would not be an interference. However, in the texts already cited by CAO et al (37) and SHILLING, DLUGOGORSKI & KENNEDY (6), the presence of potassium chloride may be interesting for the desired purpose.

[0026] The advantages of using modified LECAS are, in addition to the reasonable simplicity of its production, the achievement of a good cost-benefit ratio. Despite the initial investments in infrastructure, the final price of each batch is still divided by the number of times a salt bath can be reused, which is between 4 and 6 times. Furthermore, it is a lightweight product that, after use, can be easily handled for removal and replacement with a new load. It poses no serious risk during handling, requiring only basic PPE such as nitrile or rubber gloves. Disposal can be carried out by collecting the burned material, washing it, and reusing it in a new incorporation process. The waste generated during the production of the salt bath undergoes a simple pH neutralization and disposal process. DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 illustrates photos of the Armored Energy Metering Boxes that were installed at strategic points in the state of Rio de Janeiro, Brazil. Source: Light / Press Release. Petition 870240109851, dated 12 / 23 / 2024, page 28 / 45 15 / 25

[0028] Figure 2, from left to right, illustrates the surface view and shape of LECAs, followed by a view of their interior and internal porous structure seen through Scanning Electron Microscopy (SEM).

[0029] Figure 3 illustrates the photograph highlighting the internal view of the armored box, with the modified LECAs arranged inside, before the field test.

[0030] Figure 4 illustrates the external view of the armored box, with fire at the cable entry (left). Box opened after extinguishing the external fire and verification of the preservation of the internal circuits of the box after the test fire (right).

[0031] Figure 5 illustrates the species distribution graph for the carbonate / bicarbonate / carbonic acid equilibrium as a function of pH.

[0032] Figure 6 illustrates the comparative chromatograms between an analysis of the unmodified LECA support (blank), in red, and an analysis of the modified LECA, in black.

[0033] Figure 7 illustrates the porous structure of LECAs as seen by Scanning Electron Microscopy (SEM), before modification (figures above) and after (figures below) bicarbonate absorption into the pores, at different magnitudes. DESCRIPTION OF EXAMPLES

[0034] The three essential and primary points for the production of modified LECAs are pre-preparation, choice of salts, and production of the saline bath. The tests included the basic control parameters in the process of obtaining modified LECAs: minimum volume of the saline bath, maximum absorption capacity, influence of agitation, immersion time, pH adjustment, gravimetric analysis, analysis of CO2 release efficiency by gas chromatography with dielectric barrier discharge detector, scanning electron microscopy (SEM) analysis, and determination of the saline bath concentration. Petition 870240109851, dated 12 / 23 / 2024, page 29 / 45 16 / 25 Example 1

[0035] For the maximum absorption capacity test, the water absorption test was used as a reference, standardized, for example, by the ASTM C127, ASTM 128 (9), NBR 9776 (7) standards. It is based on submerging the dry aggregate for approximately 15 hours in water (51), which can be extended for a period of up to 24 hours (7,9). After this period, the aggregate is weighed and the mass compared to the dry mass to obtain the absorption content. The absorption of the saline solution by the LECAs (for the laboratory tests a fixed mass of approximately 50 grams was used) varied between 13.8 and 18.2% after 5 hours of immersion. However, it was observed that after 3 hours of immersion this value was already reached, remaining constant until the final 5 hours were completed. It was also concluded that, even with the change in bath conditions, the absorption did not change significantly beyond the described range.What actually changes according to the experimental conditions is the difference between the initial mass before immersion and the final mass after immersion and drying, that is, the mass of salt effectively absorbed / adsorbed. This difference is called the aggregate mass, which is obtained from gravimetric analysis of samples collected from the saline baths. Example 2

[0036] Establishing the best conditions for preparing the saline bath is extremely important. To evaluate the influence of bath volume on the aggregate mass, baths with two different ratios were prepared: 1:1 (one volume of LECA to one volume of solution) and 1:2 (one volume of LECA to two volumes of solution). The samples were immersed in the prepared saline solutions and left to stand for a predetermined period to ensure the aggregation of ions to the surface and pores of the LECA particles. The results indicated that the variation in the final volume of the saline bath (1:1 and 1:2) did not cause a significant difference in the aggregate mass. In both cases, the following was obtained: Petition 870240109851, dated 12 / 23 / 2024, pages 30 / 45 17 / 25 an average mass increase of 4.5%, suggesting that the volume ratio tested does not significantly influence the final aggregate mass result. Example 3

[0037] The baths were prepared and the LECA immersion procedures were conducted identically, differing only in terms of agitation, being: with and without agitation. It was found that there was a significant difference in the aggregated mass for the saline baths with and without agitation, with results of 1.9% and 5.7%, respectively. Agitation can promote the destabilization of the adsorbed / absorbed layer on the surface and inside the pores, causing a smaller amount of ions to be aggregated at the end of the 5-hour test. Example 4

[0038] The influence of bath concentration was tested using an experiment conducted by varying the bath concentration while maintaining the other conditions. It was observed that, for a bath with a concentration of 30 g / 100 mL, there was a mass increase of 5.4%, while for the test with a concentration of 15 g / 100 mL there was a mass increase of 2.9%. It can be concluded that absorption is dependent on the bath concentration. Example 5

[0039] The test performed with pH adjustment corroborated these latter results. A comparison was made with the 15g / 10 mL concentration test, but hydrochloric acid (concentration 1 mol / L) was added until the pH was adjusted to 8.65. The mass increase obtained was 1.4%, approximately half the value obtained for the previous test at the same concentration. This decrease in the aggregate mass value is due to two factors: the first, and probably the most pronounced, was the two-fold dilution factor. When adding acid, a volume was required that approximately doubled the volume of the initial bath. That is, with the Petition 870240109851, dated 12 / 23 / 2024, page 31 / 45 18 / 25 Due to the decrease in bath concentration caused by dilution, the aggregate mass reduced proportionally. The second factor was the loss of CO2 in the acidification process. This occurs because, at the moment of contact between the acid solution and the saline bath, the pH instantly becomes very low, which shifts the entire equilibrium towards the formation of carbonic acid and, consequently, CO2 is released, as can be seen in Figure 5 and equations 3, 4 and 5. Example 6

[0040] The analysis of the saline bath concentration can be monitored by analyzing the alkalinity, which will be carried out according to the fraction of species that will be present in the bath. For each pH, ​​there is a more suitable alkalinity method that will give greater sensitivity, precision and accuracy to the results obtained (52). Example 7

[0041] To validate the presence of bicarbonate / carbonate, i.e., incorporation efficiency, samples of the modified LECAs are collected and treated, after grinding and homogenization, with concentrated hydrochloric acid. This treatment is performed in a closed vial, generating carbon dioxide in the vial's headspace. The gas produced is collected with a syringe and analyzed by gas chromatography (GC). During the tests, a barrier discharge ionization detector (BID) was used coupled to the GC. The evidence of release in this case will be quantified through the concentration of CO2 produced by the reaction of the carbonates with the acidic medium. Figure 6 shows two chromatograms obtained at different times: the first, in red, shows the analysis of the LECA before modification, indicating that there is no detectable presence of CO2; in the second, in black, we can see the presence of the characteristic peak of carbon dioxide. Petition 870240109851, dated 12 / 23 / 2024, pages 32 / 45 19 / 25 carbon in the analyzed modified LECA sample, identified with the aid of a standard. Example 8

[0042] The structures of the LECAs before and after the incorporation process were also analyzed by Scanning Electron Microscopy (SEM). Figure 7 shows the internal pores of the LECAs before and after immersion in the bath. For the analysis, the samples were dried in an oven at 110°C before and after the baths, until constant mass. After this process, they were broken, with the aid of a tool, so that the pores were exposed. The presence of the incorporated salt can be clearly identified due to its more characteristic crystalline shape. REFERENCES 1. Missio AL, Delucis RA, Otoni CG, de Cademartori PHG, Coldebella R, Aramburu AB, et al. Thermally Resistant, Self-Extinguishing Thermoplastic Composites Enabled by Tannin-Based Carbonaceous Particulate. Polymers (Basel). 2022 Sep 1;14(18). 2. Santos P de SS. Ciência e Tecnologia de argilas. 2a. Vol. 1. 1989. 1408 p. 3. Rajput S, Saikia PP. Fire extinguishing agents: sort and comparison. Int J Res Appl Sci Eng Technol. 2018;6:557-67. 4. Lehman RL, Gentry JS, Glumac NG. Thermal stability of potassium carbonate near its melting point. 5. Jiang Z, Chow WK, Li SF. Review on additives for new clean fire suppressants. Vol. 24, Environmental Engineering Science. 2007. p. 663-74. 6. Shilling H, Dlugogorski BZ, Kennedy Eric. Extinction of diffusion flames by ultrafine water mist doped with metal chlorides. 1998; Available from: https: / / www.researchgate.net / publication / 285256253 Petition 870240109851, dated 12 / 23 / 2024, pages 33 / 45 20 / 25 7. Moravia WG, Oliveira CAS, Gumieri AG, Vasconcelos WL. Microstructural characterization of expanded clay for application as aggregate in lightweight structural concrete. Cerâmica. 2006;52:1939. 8. Santos P de SS. Science and Technology of Clays. 2nd ed. Vol. 1. 1989. 1408 p. 9. Zukri A, Nazir R, Said KNM, Moayedi H. Physical and mechanical properties of lightweight expanded clay aggregate (LECA). In: MATEC Web of Conferences. EDP ​​Sciences; 2018. 10. Rashad AM. Lightweight expanded clay aggregate as a building material - An overview. Vol. 170, Construction and Building Materials. Elsevier Ltd; 2018. p. 757-75. 11. Bodnárová L, Hela R, Hubertová M, Nováková I. Behavior of Lightweight Expanded Clay Aggregate. International Journal of Civil, Architectural, Structural and Construction Engineering. 2014;8(12):1139-42. 12. Kilinç K, Karasu B, Kivrak S. A Preliminary Research On The Properties of Lightweight Expanded Clay Aggregate [Internet]. 2008. Available from: https: / / www.researchgate.net / publication / 242312751 13. Santos FF, Santos FL de A, Santos JNS, Pereira MHN, Almeida VG, de Melo FMC, et al. Study of the granulometric variation of synthetic aggregate for the manufacture of non-structural precast concrete slabs. Revista Materia. 2018;23(1). 14. FIORILO RJEDB, APRILE PF. Oxygen encapsulating agents for fire fighting, use and production process. BR 10 2023 017944 4 A2, 2023. 15. BARTELT JE, ROBIN ML. Azeotropic composition, process for the preparation of a thermoplastic foam or thermosetting foam, process for the production of refrigeration, process for the production of an aerosol product, process for extinguishing or suppressing fire. BR20121116979 20110110, 2011. Petition 870240109851, dated 12 / 23 / 2024, pages 34 / 45 21 / 25 16. NILSSON JB. Fire retardant composition and method for its production. PI 0500548-5 B1, 2005. 17. FANTATHO F, BOLOURCHI M. Flame-retardant polymer composition and methods of use. BR20211123298 20200522, 2020. 18. GREENHILL-HOOPER M, BORRAS A, COLLARD G. Fire-suppressing foam compositions, precursors, their uses and methods of preparation. BR 11 2020 021041 2 A2, 2018. 19. PAIVA LB DE, DE OLIVEIRA AM, NETO CLDO, RISSO RR, LLBA AD. Nanostructured flame retardant agent. BR102014030429B1, 2014. 20. Opsommer A, Xiao Wu. Fire protection mortar. BR102014002644A2, 2014. 21. URBANIEC W, ZAWALSKI M. Fire-resistant, load bearing and insulating material of sandwich panel with a core based on magnesium oxychloride or oxysulfate binder. WO / 2014 / 209140, 2014. 22. MIHALCIK D, WILLIAMS J, EVANS O, BAUR D, DEKRAFFT K. Materials, systems and methods for mitigating thermal events in electrical energy storage. BR 11 2023 018332 4 A2, 2022. 23. KEUTENEDJIAN U. Method for extinguishing fires using expanded clay. PI 9901624-9 A2, 1999. 24. Tapscott RE, Sheinson RS, Babushok V, Nyden MR, Gann RG. Alternative Fire Suppressant Chemicals: A Research Review with Recommendations. 25. Hertzberg M, Cashdollar KL, Zlochower I, NG DL. INHIBITION AND EXTINCTION OF EXPLOSIONS IN HETEROGENEOUS MIXTURES. In: Twentieth Symposium (International) on Combustion / The Combustion Institute. Pittsburgh; 1984. p. 1691700. Petition 870240109851, dated 12 / 23 / 2024, pages 35 / 45 22 / 25 26. Kordylewski W, Amrogowicz J. Comparison of NaHCO 3 and NH4H2PO 4 Effectiveness as Dust Explosion Suppressants. CombustFlame. 1992;90:344-5. 27. Fan R, Jiang Y, Li W, Xiong C, Qiu R. Investigation of the physical and chemical effects of fire suppression powder NaHCO3 addition on methane-air flames. Fuel. 2019 Dec 1;257. 28. Chen X, Zhang H, Chen X, Liu X, Niu Y, Zhang Y, et al. Effect of dust explosion suppression by sodium bicarbonate with different granulometric distribution. J Loss Prev Process Ind. 2017 Sep 1;49:905-11. 29. Bakirtzis D, Delichatsios MA, Liodakis S, Ahmed W. Fire retardancy impact of sodium bicarbonate on ligno-cellulosic materials. Thermochim Acta. 2009 Mar 20;486(1-2):11-9. 30. Chelliah HK, Lazzarini AK, Wanigarathne PC, Linteris GT. COMPARSION OF THE FIRE SUPPRESSION EFFECTIVENESS OF SODIUM BICARBONAE PARTICLES AND FINE-WAER DROPLETS IN NON-PREMIXED AND PREMIXED FLAMES. In: Halon Options Technical Working Conference. 2000. p. 389-94. 31. Hamins A. FLAME EXTINCTION BY SODIUM BICARBONATE POWDER IN A CUP BURNER. In: Twenty-Seventh Symposium (International) on Combustion / The Combustion Institute. 1998. p. 2857-64. 32. Senecal JA. Flame extinguishing in the cup-burner by inert gases. Fire Saf J. 2005;40(6):579-91. 33. Kim AH, Yu AC, El Abbadi SH, Lu K, Chan D, Appel EA, et al. More than a fertilizer: Wastewater-derived struvite as a high value, sustainable fire retardant. Green Chemistry. 2021 Jun 21;23(12):4510-23. 34. Guo H, Lukovic M, Mendoza M, Schlepütz CM, Griffa M, Xu B, et al. Bioinspired Struvite Mineralization for Fire-Resistant Wood. ACS Appl Mater Interfaces. 2019 Feb 6;11(5):5427-34. Petição 870240109851, de 23 / 12 / 2024, pág. 36 / 45 23 / 25 35. Mostashari SM, Zanjanchi MA, Moafi HF, Mostashari SZ, Chaijan MRB. Thermogravimetric analysis of a cellulosic fabric incorporated by synthetic ammonium magnesium phosphate as a flame-retardan. Polymer - Plastics Technology and Engineering. 2008 Mar;47(3):307-12. 36. Yetilmezsoy K, Kocak E, Akbin HM, Ozçimen D. Utilization of struvite recovered from high-strength ammonium-containing simulated wastewater as slow-release fertilizer and fire-retardant barrier. Environmental Technology (United Kingdom). 2020 Jan 15;41(2):153-70. 37. Cao X, Ren J, Zhou Y, Wang Q, Gao X, Bi M. Suppression of methane / air explosion by ultrafine water mist containing sodium chloride additive. J Hazard Mater. 2015 Mar 1;285:311-8. 38. Shmakov AG, Korobeinichev OP, Shvartsberg VM, Yakimov SA, Knyazkov DA, Komarov VF, et al. Testing Ogranophosphorus, Organofluorine, and Metal-Containing Compounds and SolidPropellant Gas-Generating Compositions Doped with PhosphorusContaining Additives as Effective Fire Suppressants. Translated from Fizika Goreniya i Vzryva. 2006;42(6):64-73. 39. Korobeinichev OP, Shmakov AG, Shvartsberg VM, Chernov AA, Yakimov SA, Koutsenogii KP, et al. Fire suppression by low-volatile chemically active fire suppressants using aerosol technology. Fire Saf J. 2012;51:102-9. 40. Ni X, Wang X, Zhang S, Zhao M. Experimental study on the performance of transition metal ions modified zeolite particles in suppressing methane / air coflowing flame on cup burner. J Fire Sci. 2014 Sep 1;32(5):417-30. 41. Chen X, Fan A, Yuan B, Sun Y, Zhang Y, Niu Y. Renewable biomass gel reinforced core-shell dry water material as novel fire extinguishing agent. J Loss Prev Process Ind. 2019 May 1;59:14-22. Petição 870240109851, de 23 / 12 / 2024, pág. 37 / 45 24 / 25 42. Fan R, Jiang Y, Jiang H. Experimental and theoretical investigation of dry-water containing phosphoric acid for new fire suppressant. J Loss Prev Process Ind. 2021 May 1;70. 43. Chai G, Wang Y, Zhu G, Wu Z, Markert F. Experimental study on the effect of dry water materials on the fire extinguishing efficiency and suppression mechanism of wood crib fire. Fire Mater. 2024 Jun 1 ;48(4):469-82. 44. Wang Q, Wang F, Li C, Li Z, Li R. Fire extinguishing performance and mechanism for several typical dry water extinguishing agents. RSC Adv. 2021 Mar 1;11 (17):9827-36. 45. Li G, Wang Q, Liu G, Yao M, Wang Y, Li Y, et al. Hydrogel Extinguishants. Vol. 14, Nanomaterials. Multidisciplinary Digital Publishing Institute (MDPI); 2024. 46. Basak S, Samanta KK, Chattopadhyay SK, Pandit P, Maiti S. Green fire retardant finishing and combined dyeing of proteinous wool fabric. Coloration Technology. 2016 Apr 1;132(2):135-43. 47. Basak S, Samanta KK, Saxena S, Chattopadhyay SK, Narkar R, Mahangade R, et al. Flame resistant cellulosic substrate using banana pseudostem sap. Polish Journal of Chemical Technology. 2015 Mar 1;17(1):123-33. 48. Zeller KP, Schuler P, Haiss P. The hidden equilibrium in aqueous sodium carbonate solutions - Evidence for the formation of the dicarbonate anion. Eur J Inorg Chem. 2005 Jan 7;(1):168-72. 49. Dave Evans, D. H. Ripin. Bordwell pKa Table [Internet]. 2024 [cited 2024 May 28]. Available from: https: / / organicchemistrydata.org / hansreich / resources / pka / #ka-water 50. Filho OF. Ionic equilibrium: applications in analytical chemistry. São Carlos: EdUFSCar; 2016. 513. 51. CDT - ARTERIS Technological Development Center. Specific gravity and absorption of coarse aggregates. 2014; Petition 870240109851, dated 12 / 23 / 2024, pages 38 / 45 25 / 25 52. Souto RT, Fernando; Brandão G, Magda; Ferreira Pinto C, Antonieta M, et al. Comparative study of models for determining alkalinity in groundwater samples. 53. Oliveira AF. AlphaDist 7. 2020. Petition 870240109851, dated 12 / 23 / 2024, pages 39 / 45

Claims

1 / 1 CLAIMS 1. EXPANDED CLAY, applied as a fire retardant in confined environments, characterized by containing lightweight expanded clays incorporated with bicarbonate at a concentration of 85 to 100% w / w and carbonate at a concentration of 0 to 15% w / w, with a pH between 8.5 and 12.0, in which the bicarbonate concentration is at least 85%.

2. PROCESS for producing the expanded clay defined in claim 1, characterized by the following steps: a. Washing the lightweight expanded clays with water; b. Preparing a saline solution; c. Immersing the lightweight expanded clays for 4 hours at room temperature in a saline solution without agitation, where the concentration ratio by volume of expanded clay and the solution is 1:1; d. Controlling the pH between 8.0 and 12.0; e. Removing the clays from the bath; f. Drying the clays at room temperature; g. Packaging the dried clays.

3. PROCESS for validating expanded clay produced according to the process of claim 2, characterized by the following steps: a. Collect a sample of the produced clays; b. Grind the clays until a uniform powder is obtained; c. Treat the sample with concentrated hydrochloric acid in a closed vial; d. Collect the generated CO2 with a syringe; e. Analyze the CO2 sample by gas chromatography using a barrier discharge ionization detector; f. Measure the CO2 concentration.

4. USE of expanded clay produced according to the process of claims 1 to 3, characterized by its application as a fire retardant in confined environments. Petition 870240109851, dated 12 / 23 / 2024, pp. 40 / 45

Images