FIELD OF THE DISCLOSURE

[0001] The present disclosure relates to lightweight aggregate compositions having suitable characteristics for forming or lining containers for making, transporting, or storing high-temperature materials.

BACKGROUND

[0002] Calcium hexa-aluminate (CA6) is the most thermodynamically stable calcium aluminate phase and is, therefore, chemically stable in corrosive environments. Because of its lightweight characteristics and the absence of silica, CA6 has been used in environments with reducing atmospheres in which silica-containing materials may decompose. These applications include hydrogen transfer lines in the petrochemical industry and also insulation in coke furnaces. However, typical aggregates that include CA6 suffer from high water reactivity, poor aging effects, friability, and strength issues.

[0003] The production of an advantageous lightweight aggregate composition is particularly problematic when the cementitious material is used as a refractory. In typical refractory compositions, the high temperatures experienced serve to enhance dimensional changes while facilitating undesired chemical reactions that are of little consequence at lower operating temperature.

[0004] Thus, there exists a need for lightweight refractory compositions for addressing the aforementioned limitations of existing refractory compositions. The ability to control set properties and strength facilitates the use of cementitious materials particularly as refractories.

SUMMARY

[0005] A lightweight refractory composition is provided that includes a calcium aluminate aggregate and a phosphate binder. The calcium aluminate aggregate includes monocalcium dialuminate (CA2), calcium hexa-aluminate (CA6), or combinations thereof. The phosphate binder includes phosphoric acid or a derivative thereof. When the calcium aluminate aggregate and the phosphate binder are intermixed in appropriate proportions, a temperature resistant material is obtained upon forming the lightweight refractory composition. DETAILED DESCRIPTION

[0006] The materials as provided in this disclosure have utility as a lightweight refractory composition suitable for use in high temperature applications like housing molten metals, illustratively molten aluminum. Control over properties such as water reactivity, aging, and strength of the provided refractory materials are obtained through mixing particular calcium aluminate aggregates with phosphoric acid or a chemical derivative thereof as a binder to form a lightweight refractory composition showing improvements over traditional compositions. As a result, the reaction between the phosphate binder and the calcium aluminate aggregate produces a lightweight refractory composition having excellent thermal conductivity and heat resistance stemming, at least in part, from having a small average pore size, thereby creating a tortuous path for fractionated molecules attempting to enter the lightweight refractory composition.

[0007] As used herein, the terms “phosphoric acid or a chemical derivative thereof’ and “phosphate binder” mean phosphoric acid or its chemical derivatives that include at least one phosphate ion. Suitable chemical derivatives may include, but are not limited to, phosphoric acids of different grades such as different levels of dilution or impurity, monocalcium phosphate (MCP), dicalcium phosphate (DCP), zinc phosphate, aluminum phosphate such as monoaluminum phosphate, or any combination thereof. In some aspects, a phosphoric acid or a chemical derivative thereof excludes sodium phosphates. The phosphate binder, which includes the phosphoric acid or a chemical derivative thereof, may be diluted to any suitable level.

[0008] As used herein the term “lightweight” is understood as a material having a density less than 120 pounds per cubic foot.

[0009] This disclosure is based, in part, on the unexpected finding that intermixing the calcium aluminate aggregate, as described herein, with the phosphate binder yields a lightweight refractory composition having superior qualities. More specifically, aggregates that include a sufficient amount of the CA2 phase of the calcium aluminate aggregate undergoes an exothermic reaction when intermixed with a phosphate binder, such as phosphoric acid, leading to the formation of a cementitious phase with a long initial working time, suitable for enhanced periods of manipulation required in many production processes. In one or more embodiments, the initial working time and setting time of this mixture may, for example, be prolonged and can be conveniently adjusted for up to 24 hours or longer. Once set, the lightweight refractory composition shows a variety of benefits over typical aggregates. For example, as will be described in greater detail later in this disclosure, the presently described composition has excellent thermal conductivity, which reduces heat radiation transfer significantly. Moreover, in one or more embodiments, the resulting composition has a small pore size, on the order of 80 Angstroms (A) to 90 A, which results in a tortuous path for fractioned molecules to enter a structure that has been formed from the lightweight refractory composition. As such, the lightweight refractory composition, as described herein, may reduce the depth of penetration of reactants and controls the depth of unwanted buildup, such as coke buildup, when exposed to such molten compounds.

[0010] According to an embodiment of the present disclosure, a lightweight refractory composition includes: a calcium aluminate aggregate comprising monocalcium dialuminate, monocalcium hexa-aluminate, or combinations thereof; and a phosphate binder comprising phosphoric acid or a chemical derivative thereof, the phosphate binder intermixed with the calcium aluminate aggregate so as to form the lightweight refractory composition. Incorporation of the selected calcium aluminate aggregate into the lightweight refractory composition results in a high-strength refractory.

[0011] In some embodiments, the calcium aluminate aggregate may include CA2 at up to 100 wt%, based on the total weight of the calcium aluminate aggregate. As previously described, CA2 is able to react with the phosphoric acid binder that allows for a long setting time, which means that the mixture is suitable for enhanced periods of manipulation - for example, up to 24 hours or more. In some embodiments, the lightweight refractory composition may include CA2 in an amount of up to 50 wt%, based on the total weight of the calcium aluminate aggregate. In further embodiments, CA2 is present from 40 wt% to 60 wt%, 45 wt% to 55 wt%, 40 wt% to 50 wt%, 45 wt% to 50 wt%, or 48 wt% to 50 wt%, based on the total weight of the calcium aluminate aggregate. It should be appreciated that regardless of which embodiments of the calcium aluminate aggregate are selected, CA6 may be present in the calcium aluminate aggregate at up to 100 wt%, based on the total weight of the calcium aluminate aggregate. In some embodiments, CA6 is present from 40 wt% to 60 wt%, 45 wt% to 55 wt%, 40 wt% to 55 wt%, 50 wt% to 60 wt%, 50 wt% to 55 wt%, or 50 wt% to 52 wt%, based on the total weight of the calcium aluminate aggregate.

[0012] The calcium aluminate aggregate may also be categorized according to the composition of the materials used in forming the composition, regardless of the final amounts CA2 and CA6 that are respectively present in the calcium aluminate aggregate. Namely, the calcium aluminate aggregate may include aluminum oxide, calcium oxide, and optionally silicon dioxide and/or iron(iii) oxide. In some embodiments, the calcium aluminate aggregate includes from 50 wt% to 90 wt% aluminum oxide, from 10 wt% to 50 wt% calcium oxide, optionally less than or equal to 2 wt% silicon dioxide, and optionally less than or equal to 1 wt% iron(iii) oxide, based on the total weight of the calcium aluminate aggregate. In some embodiments, the calcium aluminate aggregate includes from 65 wt% to 93 wt% aluminum oxide, from 7 wt% to 35 wt% calcium oxide, optionally less than or equal to 2 wt% silicon dioxide, and optionally less than or equal to 1 wt% iron(iii) oxide, based on the total weight of the calcium aluminate aggregate. In some embodiments, the calcium aluminate aggregate includes from 80 wt% to 85 wt% aluminum oxide, from 15 wt% to 20 wt% calcium oxide, optionally less than or equal to 0.6 wt% silicon dioxide, and optionally less than or equal to 0.3 wt% iron(iii) oxide, based on the total weight of the calcium aluminate aggregate.

[0013] In some embodiments, the calcium aluminate aggregate includes from 50 wt% to 93 wt% aluminum oxide, 50 wt% to 90 wt% aluminum oxide, from 60 wt% to 90 wt% aluminum oxide, from 70 wt% to 90 wt% aluminum oxide, from 78 wt% to 86 wt% aluminum oxide, from 79 wt% to 85 wt% aluminum oxide, from 80 wt% to 84 wt% aluminum oxide, from 80 wt% to 83 wt% aluminum oxide, from 79 wt% to 83 wt% aluminum oxide, from 80 wt% to 82 wt% aluminum oxide, from 81 wt% to 84 wt% aluminum oxide, from 81 wt% to 83 wt% aluminum oxide, from 67 wt% to 71 wt% aluminum oxide, from 68 wt% to 70 wt% aluminum oxide, at least 68.5 wt% aluminum oxide, about 69 wt% aluminum oxide, or about 82% aluminum oxide, based on the total weight of the calcium aluminate aggregate. In some embodiments, the calcium aluminate aggregate includes from 7 wt% to 50 wt% calcium oxide, 10 wt% to 50 wt% calcium oxide, from 10 wt% to 40 wt% calcium oxide, from 10 wt% to 35 wt% calcium oxide, from 10 wt% to 25 wt% calcium oxide, from 10 wt% to 20 wt% calcium oxide, from 13 wt% to 20 wt% calcium oxide, from 15 wt% to 19 wt% calcium oxide, from 15 wt% to 18 wt% calcium oxide, from 16 wt% to 18 wt% calcium oxide, from 16 wt% to 17 wt% calcium oxide, from 25 wt% to 35 wt% calcium oxide, from 29 wt% to 33 wt% calcium oxide, at most 31 wt% calcium oxide, about 31 wt% calcium oxide, or about 17 wt% calcium oxide, based on the total weight of the calcium aluminate aggregate.

[0014] The calcium aluminate aggregate may optionally include silicon dioxide. In some embodiments, the calcium aluminate aggregate includes less than or equal to 2 wt% silicon dioxide, based on the total weight of the calcium aluminate aggregate. In other embodiments, the calcium aluminate aggregate includes from 0.1 wt% to 2 wt% silicon dioxide, from 0.1 wt% to 1 wt% silicon dioxide, from 0.2 wt% to 0.6 wt% silicon dioxide, from 0.2 wt% to 0.5 wt% silicon dioxide, from 0.2 wt% to 0.4 wt% silicon dioxide, from 0.1 wt% to 0.2 wt% silicon dioxide, about 0.3 wt% silicon dioxide, less than or equal to 0.8 wt%, about 0.8 wt%, or about 0.2 wt% silicon dioxide, based on the total weight of the calcium aluminate aggregate. In some embodiments, the calcium aluminate aggregate comprises no silicon dioxide or essentially no silicon dioxide.

[0015] The calcium aluminate aggregate, in some embodiments, may further include iron(iii) oxide. In some embodiments, the calcium aluminate aggregate includes less than or equal to 1 wt% iron(iii) oxide, less than or equal to 0.5 wt% iron(iii) oxide, less than or equal to 0.4 wt% iron(iii) oxide, less than or equal to 0.3 wt% iron(iii) oxide, less than or equal to 0.2 wt% iron(iii) oxide, less than or equal to 0.1 wt% iron(iii) oxide, about 0.07 wt% iron(iii) oxide, less than 0.01 wt% iron(iii) oxide, or about 0.001 wt% iron(iii) oxide, based on the total weight of the calcium aluminate aggregate. In some embodiments, the calcium aluminate aggregate comprises no iron(iii) oxide or essentially no iron(iii) oxide.

[0016] Regardless of the chemical composition of the calcium aluminate aggregate, its porosity, Brunauer-Emmett-Teller (BET) surface area, specific gravity, and pore size must be suitable for producing the lightweight refractory composition. As previously described, these pore-related characteristics result in a litany of benefits, such as improved thermal conductivity, increased strength, and reduction of reactant penetration and its subsequent buildup.

[0017] In some embodiments, the calcium aluminate aggregate has a porosity ranging from 50% to 75%. In some embodiments, the calcium aluminate aggregate has a porosity ranging from 55% to 75%, 65% to 75%, 68% to 72%, from 68.5% to 71.5%, from 69% to 71%, or about 70%. Even though the calcium aluminate aggregate has a relatively high porosity, its small pore size prevents reactant penetration when utilized as a component in a refractory composition. For instance, the calcium aluminate aggregate may have an average pore size from 80 A to 90 A. In certain embodiments, the calcium aluminate aggregate has a pore size from 82 A to 89 A, from 84 A to 88 A, or about 86 A. In contrast, typical aggregates, such as SLA-92 (commercially available from Almatis Premium Alumina), have average pore sizes that are nearly 600 times larger than those of the present disclosure. As such, typical aggregates may have decreased performance, such as high shrinkage or diminished control of coke buildup when used in a refractory composition.

[0018] It will be appreciated by those of ordinary skill in the art that the specific gravity of an aggregate is defined as the ratio of the weight of aggregate to the weight of an equal volume of water. The specific gravity of an aggregate may be considered a measure of strength of the aggregate. Specifically, aggregates having low specific gravity are generally considered to be weaker than those with high specific gravity. This property helps in a general identification of aggregates. In some embodiments, the calcium aluminate aggregate of the present disclosure has a specific gravity from 2.5 g/cm ³ to 3.5 g/cm ³ , which is substantially greater than specific gravities for other typical lightweight aggregates, such as SLA-92 (having a specific gravity of about 0.8 g/cm ³ to 0.95 g/cm ³ ). In other embodiments, the calcium aluminate aggregate has a specific gravity from 2.7 g/cm ³ to 3.3 g/cm ³ , from 2.9 g/cm ³ to 3.2 g/cm ³ , from 2.95 g/cm ³ to 3.15 g/cm ³ , from 3.0 g/cm ³ to 3.1 g/cm ³ , or about 3.07 g/cm ³ . Such ranges of specific gravity allow for the calcium aluminate aggregate to maintain its strength, while also having high levels of porosity with small pore sizes.

[0019] It will also be appreciated by those of ordinary skill in the art that BET surface area is an analysis technique for the measurement of the specific surface area of materials, which corresponds to the adhesion of atoms or molecules of gas to a surface. The greater the BET surface area of the material, the greater the adhesion of atoms or molecules. Here, in some embodiments, the calcium aluminate aggregate has a BET surface area from 0.45 m ² /g to 0.65 m ² /g. In other embodiments, the calcium aluminate aggregate has a BET surface area from 0.5 m ² /g to 0.6 m ² /g, from 0.52 m ² /g to 0.58 m ² /g, from 0.54 m ² /g to 0.56 m ² /g, or about 0.55 m ² /g, all of which are suitable for providing the calcium aluminate aggregate with the previously described structural and performance-based benefits.

[0020] In some embodiments, the calcium aluminate aggregate comprises primary particles having an average particle diameter of greater than 0 to 10 mm, greater than 0 to 6 mm, greater than 0 to 3 mm, greater than 0 to 1 mm, 0.1 to 0.7 mm, 0.2 to 0.5 mm, 0.3 to 0.4 mm, 1 to 6 mm, 1 to 3 mm, 3 to 10 mm, or 3 to 6 mm.

[0021] In one or more embodiments, the calcium aluminate aggregate may be formed from a molten mixture of the constituent ingredients, namely, aluminum oxide, calcium oxide, and optionally silicon dioxide and/or iron(iii) oxide. For example, the constituent ingredients may be liquified in a furnace, such as a submerged electrode furnace (SEF). The molten mixture may then be cooled using a blowing process, thereby forming droplets of the calcium aluminate aggregate. The blowing process may comprise using an air knife with an air velocity of Mach 0.5 to Mach 2, Mach 0.5 to Mach 1, or about Mach 0.75. In some embodiments, the blowing process may be conducted in water. In other embodiments, the blowing process may further comprise using a cooling gas to accelerate solidification. In some embodiments, the calcium aluminate aggregate particles are spherical and/or have an aspect ratio of no more than 2. In some embodiments, the calcium aluminate aggregate includes less than 10 wt%, less than 5 wt%, less than 2 wt%, or less than 1 wt% of particles having an aspect ratio of greater than 2 (i.e., fibers).

[0022] In some embodiments, one or more additional components may be added to the lightweight refractory composition in any desirable amount to adjust the properties of the lightweight refractory composition. For example, additional components may be added to the lightweight refractory composition that alter the composition’s porosity, BET surface area, specific gravity, pore size, density, or other like characteristics. In some embodiments, therefore, the lightweight refractory composition may further include calcined alumina, water, a cementitious component, or other similar substances. Regardless of whether an additional component is added to the lightweight refractory composition, the calcium aluminate aggregate may be present from 70 wt% to less than 100 wt%, based on the total weight of the lightweight refractory composition.

[0023] In some embodiments, the calcined alumina is present in the lightweight refractory composition from 1 wt% to 15 wt%, based on the total weight of the lightweight refractory composition. In other embodiments, the calcined alumina may be present in the lightweight refractory composition from 2 wt% to 14 wt%, from 3 wt% to 12 wt%, from 4 wt% to 11 wt%, or from 5 wt% to 10 wt%. Without being bound by theory, it is believed that the addition of calcined alumina to the lightweight refractory composition may increase the composition’s setting time and density, should such properties be desirable.

[0024] A cementitious component may also be optionally added to the lightweight refractory composition, regardless of whether calcined alumina has been added to the composition. In some embodiments, the cementitious component is present from 1 wt% to 15 wt%, based on the total weight of the lightweight refractory composition. In other embodiments, the cementitious component may be present in the lightweight refractory composition from 2 wt% to 14 wt%, from 3 wt% to 12 wt%, from 4 wt% to 11 wt%, or from 5 wt% to 10 wt%. Without being bound by theory, it is believed that the addition of the cementitious component to the lightweight refractory composition may also increase the composition’s setting time and density, should such properties be desirable. Suitable cementitious components may include, but are not limited to, calcium aluminate cements (e.g., 80% alumina cements). One commercially suitable calcium aluminate cement includes CA- 25R, an 80% alumina cement available from Almatis Chemicals, Leetsdale, PA.

[0025] As previously stated, the lightweight refractory composition includes a phosphate binder, which is intermixed with the calcium aluminate aggregate to form the lightweight refractory composition. The phosphate binder includes phosphoric acid or a chemical derivative thereof, which is defined above. In some embodiments, the phosphate binder is intermixed with the calcium aluminate aggregate at a weight ratio (phosphate binder to calcium aluminate aggregate) of from 0.1 to 10, from 0.2 to 5, from 0.4 to 2.5, from 0.5 to 2, from 0.1 to 0.5, from 0.2 to 0.35, about 0.25, or about 0.3. In some embodiments, the phosphate binder includes phosphoric acid, which may be diluted to any suitable concentration (e.g., in some embodiments, the phosphoric acid is diluted to a concentration of between 15% and 55%) before, during, or after being intermixed with the calcium aluminate aggregate. Without being bound by theory, it is believed that the exothermic reaction between the phosphate binder and the calcium aluminate aggregate further enables long setting or working times of the lightweight refractory composition. Moreover, the phosphate binder allows for the lightweight refractory composition to bond quickly with any existing refractory linings and allows for the lightweight refractory composition to be fired shortly after casting. Notably, unlike typical phosphate-bonded refractory compositions, the lightweight refractory composition described within the present disclosure does not show high shrinkage.

[0026] Regardless of which specific formulation of the lightweight refractory composition is chosen, its density must be suitable for preventing metal penetration or corrosion when utilized as a refractory lining. In some embodiments, the lightweight refractory composition has a density of less than or equal to 1.6 g/cm ³ . In some embodiments, the lightweight refractory composition has a density of less than or equal to 1.5 g/cm ³ , less than or equal to 1.4 g/cm ³ , or about 1.35 g/cm ³ . In further embodiments, the lightweight refractory composition has a density from to 1.2 g/cm ³ to 1.6 g/cm ³ , from to 1.25 g/cm ³ to 1.5 g/cm ³ , or from to 1.3 g/cm ³ to 1.4 g/cm ³ . [0027] It will be appreciated by those of ordinary skill in the art that the addition of silica to refractory compositions may decompose hydrogen transfer lines commonly used in the petrochemical industry. As such, in some embodiments, the lightweight refractory composition described in the present disclosure is substantially free of silica or any other compounds that include silicon or chemical derivatives thereof. In some embodiments, silica is optionally present at 2 wt% or less, 1 wt% or less, 0.5 wt% or less, 0.25 wt% or less, 0.1 wt% or less, or 0.05 wt% or less.

[0028] The lightweight refractory composition, in some embodiments, has a porosity of greater than or equal to 50%. This porosity allows the composition to maintain its lightweight properties while also preventing metal penetration or corrosion. In other embodiments, the lightweight refractory composition has a porosity of greater than or equal to 52%, 54%, 56%, 58%, 60%, 65%, or 70%.

[0029] A longer working, or setting time, of the lightweight refractory composition may be desirable in certain situations. As such, the lightweight refractory composition described in the present disclosure may have an initial working time of greater than 24 hours. The initial working time may be shortened or prolonged depending on the exact formulation chosen for the composition, all of which are described and contemplated within this disclosure. In some embodiments, the initial working time of the lightweight refractory composition may be equal to or greater than 1 hour, optionally 40 minutes, optionally 20 minutes, optionally 10 minutes. The total setting time of the lightweight refractory composition may be greater than or equal to 2 hours, 4 hours, 6 hours, 8 hours, 12 hours, 24 hours, or 48 hours. The initial working time and setting time may be further adjusted by the inclusion of one or more additional components, such as the previously-described calcined alumina and/or cementitious component.

[0030] The lightweight refractory composition may be at least partially or fully resistant to penetration by molten aluminum, such as aluminum at temperatures greater than 1300 °F. Further, the lightweight refractory composition may be at least partially or fully non-wetting when contacted with molten aluminum.

[0031] It will be appreciated by those of ordinary skill in the art that the term “cold crush strength” represents the ability of a product to resist failure under compressive load at room temperature. It is relevant to refractory performance and may be used as an indicator of abrasion resistance. The higher the cold crush strength of a material, the greater the resistance the material is to abrasion. In some embodiments, the lightweight refractory composition has a cold crush strength of greater than or equal to 500 psi.

[0032] A lightweight refractory composition, depending on choice of components, is well suited for a variety of uses illustratively including refractory articles such as fireplaces, furnace linings, refractory castables, a lining material for casting launders, ladle linings, insulating back-up linings, and patch materials for kilns, furnaces and incinerators.

EXAMPLES

[0033] Example 1:

[0034] Two lightweight refractory compositions were formed. In the first composition, 6500 g of a dry calcium aluminate CA6/CA2 aggregate (commercially available as CAHP-82 from BNZ Materials, Inc. (Zelienople, PA)) was mixed with 2000 mL of 25% H3PO4 diluted acid (functioning as the phosphate binder), 1000 g of 80% alumina cement, and 2500 g of calcined alumina. The mixture resulted in a lightweight refractory composition with an initial working time of 20 minutes and a total setting time of 12 hours. The initial working time of this lightweight refractory composition was found to be nearly double compared to pure monocalcium aluminate (CA) formulations.

[0035] At 1500 °F, the first lightweight refractory composition had a permanent linear change (PLC) of -0.16%, a cold crush strength (CCS) of 510 psi, a modulus of rupture of (MOR) of 133 psi, and a density of 1.34 g/cm ³ . At 2000 °F, the first lightweight refractory composition had a PLC of -0.43%, a MOR of 226 psi, and a density of 1.35 g/cm ³ .

[0036] An aluminum penetration test was conducted with the first lightweight refractory composition using the following steps. First, a vessel was cast with the first lightweight refractory composition. The vessel was then fired to 1500 °F and charged with 500 grams of 7075 aluminum alloy, an aluminum metal considered to be one of the most aggressive alloys as it contains magnesium, zinc, and manganese in addition to aluminum. The aluminum alloy was stirred while 15 grams of aluminum cover salt containing sodium chloride, potassium chloride, and sodium aluminum hexafluoride were added to protect the aluminum alloy from oxidation. The vessel was then held at 1500 °F for 100 hours. After 100 hours, the vessel was removed, and the aluminum alloy was discharged. No metal penetration or corrosion was observed upon reviewing and analyzing the vessel, indicating that the lightweight refractory composition is suitable for use as a refractory article or lining material for casting launders, ladle linings, or insulating back-up linings. [0037] A second formulation was also produced containing 6500 g of the dry calcium aluminate CA6/CA2 aggregate, which was mixed with 1600 mL 25% of H3PO4 diluted acid (functioning as the phosphate binder), 100 g of 80% alumina cement, and 3400 g of calcined alumina. The mixture resulted in a lightweight refractory composition with an initial working time of 45 minutes and a total setting time of 12 hours. The initial working time of this lightweight refractory composition was also found to be nearly double compared to pure monocalcium aluminate (CA) formulations.

[0038] At 1500 °F, the second lightweight refractory composition had a PLC of -0.21%, a CCS of 590 psi, a MOR of 133 psi, and a density of 1.35 g/cm ³ . At 2000 °F, the second lightweight refractory composition had a PLC of -0.39%, a MOR of 231 psi, and a density of 1.39 g/cm ³ . Based on these properties, it is also believed that the second lightweight refractory composition would be suitable for use as a refractory article or lining material for casting launders, ladle linings, or insulating back-up linings.

[0039] Example 2:

[0040] A lightweight refractory composition was formed by melting a calcium-aluminate composition with about 31% CaO (available under the tradename SECAR 71 from Imerys S.A.) in submerged electrode furnace (SEF). The orifice of the SEF was drilled out to 0.5 inches to allow the molten mixture to exit and the plug was embedded in S1O2 to create a low viscosity flux. An air knife was installed proximate the orifice and the molten mixture was solidified via a blowing process to form glassy, spherical calcium aluminate aggregate particles (fiber content of less than 5 wt%) having an average particle diameter of 400 to 500 microns. [0041] A portion of the calcium aluminate aggregate particles was intermixed with dilute phosphoric acid. The material set overnight, which confirmed that the particles are reactive and provide a beneficially slow setting time.

[0042] A separate portion of the calcium aluminate aggregate particles was mixed with water. The particles were submerged in water and reached a pH of 9 instantly, which indicates Ca+ dissolution and potential binder activity. After being submerged in water for 12 hours, the particles appeared opaque and some particles appeared to have macroscopic surface crystallization.

[0043] These examples are not intended to limit the scope of the present disclosure as described herein. These examples are for purposes of illustration and it will be evident to those persons of ordinary skill in the art that numerous variations and details of the instant disclosure may be made without departing from the instant disclosure as set forth herein.

[0044] The foregoing description is illustrative of particular embodiments of the disclosure, but is not meant to be a limitation upon the practice thereof. The following claims, including all equivalents thereof, are intended to define the scope of the disclosure.