High-emissivity fire-resistant material and fire-resistant components formed therefrom

Abstract

The particulate high-emissivity (high ε) refractory product comprises: (a) a particulate refractory substrate, including at least one particulate binder material, at least one particulate refractory raw filler material, and, optionally, at least one refractory additive; and (b) a mixture of high ε pigments in an amount sufficient to impart a high ε characteristic of at least 0.80 to the refractory product upon curing. The high ε pigment is uniformly dispersed throughout the particulate refractory substrate, making it less susceptible to loss of high ε characteristics over time. The particulate high ε product may be formed into a castable wet mix, an aqueous slurry, or an insulating aqueous foam, and cured to form a component of a high-temperature refractory structure (e.g., a wall or ceiling of a refractory furnace) having high ε characteristics.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of domestic priority to U.S. Provisional Patent Application No. 63 / 050,381, filed July 10, 2020, the entire contents of which are expressly incorporated herein by reference.

[0002] Embodiments disclosed herein generally relate to high-temperature resistant (refractory) materials. In a preferred form, embodiments disclosed herein relate to refractory materials that exhibit high emissivity (ε) characteristics upon curing. Preferred embodiments disclosed herein relate to refractory materials having high emissivity (high ε) pigments uniformly dispersed throughout the material. The refractory material may be in the form of a dry mixture of particulate components, and the dry mixture may be formed into an aqueous slurry, a refractory foam, or a castable refractory material.

[0003] Background Art and Summary of the Invention High-emissivity coatings are currently being produced for industrial furnaces and process heaters. These coatings are prepared from ceramic substrates using high-emissivity pigments containing materials such as cobalt oxide, nickel oxide, chromium oxide, and iron oxide. Many such pigments are commercially available and can be mixed into the base refractory material at about 1% to about 5% by weight, based on the dry weight of the refractory material. The coating is then applied to the interior surfaces of existing furnaces as a thin layer (e.g., about 1.6 mm thick).

[0004] Stefan-Boltzmann equation (P=εAσT 4) where ε is emissivity, the change in emissivity provided by a high-emissivity coating can result in an increase in radiative heat transfer on the order of 40%. Because emissivity is a surface effect, the benefit of changing the emissivity with a coating on the outermost furnace interior surface is noteworthy. For example, the coating improves the radiative heat transfer of refractory surfaces to the furnace load in a natural gas-fired furnace by increasing the emissivity of the refractory surface (which is typically quite low, between 0.4 and 0.65) to approximately 0.92.

[0005] High-emissivity coatings therefore provide operational and financial benefits in manufacturing industries with high energy costs, such as smelters, chemical plants, and steel finishing plants. This benefit is immediate (i.e., immediately after coating) and persists as long as the coating remains on the furnace interior surface. However, as the refractory components deteriorate, conventional high-ε coatings applied to furnace interior surfaces also deteriorate and spall. Thus, as this itself reveals, the high-ε benefits provided by the coating diminish over time as the coating spalls.

[0006] Another problem with high-ε refractory coatings is the conventional use of ceramic refractory fibers (CRFs), typically aluminosilicates, to form ceramic blankets and furnace interior surfaces, providing thermal insulation. While these CRFs provide increased insulation, they also break down over time and become brittle and brittle when exposed to high temperatures. Turbulence from the combustion in the furnace, caused by the gases and air blowing through the furnace, can cause degraded CRFs to break off and travel downstream within the furnace. As these fibers travel downstream, they can become trapped in the pre-stack heat recovery system, reducing its efficiency and eventually clogging it. Alternatively, the fibers can continue downstream and, upon exiting the system, deposit in the surrounding environment. Because CRFs have been shown to be carcinogenic, this issue poses health and environmental risks and must be strictly avoided.

[0007] It is an object of embodiments disclosed herein to incorporate high-emissivity pigments directly into refractory substrates, such as refractory insulating foams, cast-in-place materials, spray materials, brick, molding compounds, or other precast refractory castable materials for high-temperature (e.g., above about 450°F (232°C)) applications. Exemplary applications in which the refractory products of the present application may be utilized include the walls and ceilings of high-temperature melting furnaces used in the aluminum industry. By incorporating the high-ε pigment into the refractory substrate and dispersing the pigment throughout the refractory substrate, a concentration of the pigment is uniformly distributed throughout the refractory structure formed from the material. Alternatively, a concentration of the high-ε pigment can be uniformly distributed within the refractory substrate to a specific, predefined depth (e.g., greater than 1 inch).

[0008] Incorporating pigments into the fire-resistant substrate improves the emissivity of the material and eliminates problems associated with the degradation of coatings that flake off over time. Because the high-ε pigments are physically present in the fire-resistant material, cleaning the surface of the fire-resistant material to remove emissivity-reducing contaminants that accumulate on the surface can expose the fire-resistant material and restore its high-ε properties. Furthermore, because pigments are traditionally applied only to the surface, incorporating pigments directly into the fire-resistant substrate only marginally increases the overall production cost. Because the project is complete once the material is installed, i.e., no additional coatings or layers need to be applied to the material surface to achieve high-ε properties, providing a high-ε surface is a one-step process using the present high-ε fire-resistant material, in which the high-ε pigments are physically incorporated into the fire-resistant substrate.

[0009] These and other aspects and advantages of the present invention will become more apparent upon careful consideration of the following detailed description of preferred representative embodiments thereof. DETAILED DESCRIPTION OF THE INVENTION

[0010] Disclosed are granulated refractory materials for use in high-temperature applications, having high-emissivity pigments incorporated therein, and methods by which the refractory materials may be used as flowable masses that, upon curing, form high-temperature refractory structures (e.g., walls, ceilings, blocks, etc., utilized in high-temperature environments). Refractory materials include, for example, refractory insulating foams, cast-in-place materials, sprayed materials, bricks, molding compounds, or other precast refractory castable materials for use in high-temperature applications and environments. The term "high temperature," as it relates to this disclosure, is 450°F (232°C) or higher, such as 450°F to 2800°F (232°C to 1538°C) or even 1200°F to 2800°F (649°C to 1538°C).

[0011] By incorporating the high-emissivity pigment directly into the refractory substrate, the concentration of the pigment in the resulting granular refractory material is uniformly distributed throughout at least a portion of, or even the entire depth of, the resulting refractory structure or component upon curing. This uniform distribution of the high-ε pigment is in stark contrast to conventional high-ε coatings, in which the high-ε pigment is present only in a relatively thin top coating. Thus, according to embodiments disclosed herein, the high-ε pigment is less susceptible to flaking or shedding due to some other mechanical force / damage than conventional thin high-ε coatings. Furthermore, the refractory base material to which the conventional high-ε coating is applied does not need to be dried, thereby minimizing idling of the equipment and refractory components.

[0012] High-emissivity pigments may be incorporated into virtually any type of dry granulated refractory substrate mixture, including high-cement, low-cement, cement-free, colloidal, slurry, and phosphate-bound systems. Thus, the refractory substrate dry mixture typically includes at least one particulate binder material, at least one particulate refractory raw filler material, and optionally at least one refractory additive.

[0013] The particulate refractory substrate typically has a predetermined target particle size distribution (D) that provides suitable flowability to an aqueous slurry of the particulate refractory material. pstIn a preferred embodiment, the particulate refractory substrate typically has a D pst are: 4 mesh <2%; 10 mesh = 23% ± 5%; 20 mesh = 42% ± 5%; 100 mesh = 58% ± 5%; 200 mesh = 64% ± 5% and -325 mesh = 32% ± 5%.

[0014] The particulate binder material is typically present in the refractory substrate dry mix in an amount of about 2% to about 30% by weight, preferably about 2% to about 10% by weight (e.g., about 4% by weight), based on the total weight of the particulate high ε refractory material product. The binder material is added in an amount that promotes the development of green mechanical properties of the cured refractory material. One or more binder materials may be used in the refractory substrate dry mix.

[0015] Representative particulate binder materials include calcium aluminate cement, hydratable alumina, phosphate-based binders, sodium silicate, colloidal silica, and colloidal alumina. Representative calcium aluminate cements include SECAR® 71 (CAS #65997-16-2, a hydraulic binder with the following composition: Al2O3 (≥68.5%), CaO (≤31.0%), SiO2 (≤0.8%), and Fe2O3 (≤0.4%), sold by KERNEOS Inc.). Representative hydratable aluminas include DYNABOND® 3 (CAS #1344-28-1, a flash-calcined hydratable alumina powder sold by ALUCHEM, Inc.). Representative phosphate-based binders include 85% Phosphoric Acid FG (sold by Brenntag) and monoaluminum phosphate. A representative sodium silicate is SS®-C20 (CAS # 1344-09-8, sodium silicate powder) sold by PQ Corporation. A representative colloidal silica is LUDOX® TM-40 (CAS # 7631-86-9, 40 wt% water suspension, sold by Sigma Aldrich). A representative colloidal alumina is ALR-0105 (0.5 μm fine alumina abrasive powder) sold by Pace Technologies.

[0016] The particulate refractory raw filler material is added to impart desired general properties to the refractory material, such as final chemical properties specific to each end use. The refractory raw filler material is typically present in an amount of from 50% to about 99% by weight, preferably from about 75% to about 95% (e.g., from about 85% to about 90% by weight) based on the total dry weight of the refractory substrate, relative to the total weight of the particulate high ε refractory material product.

[0017] Refractory raw filler materials that are suitable for use in the dry mix of refractory substrates include one or more of alumina silicates, alumina, silicon carbide, zirconia-containing raw materials, magnesium-aluminum spinel, silica fume, burnt flint, fused silica, and silica sand. The refractory raw filler provides the general properties of the refractory material, including the final chemistry specific to each application. The particle size of the particulate refractory raw filler is finer than 3 mesh, e.g., below 40 mesh (e.g., about 48 mesh, 100 mesh, 200 mesh, 325 mesh, 400 mesh, 600 mesh, etc.).

[0018] Representative aluminosilicates that may be utilized include kyanite (e.g., Virginia Kyanite® 48 mesh, 100 mesh, 200 mesh, or 325 mesh, available from Kyanite Mining Corporation, Dillwyn, Virginia), mullite (e.g., Virginia Mullite 48 mesh, 100 mesh, 200 mesh, or 325 mesh, available from Kyanite Mining Corporation, Dillwyn, Virginia, and MULCOA® 47, 60, or 70 in particle sizes finer than 3 mesh, e.g., 48 mesh, 100 mesh, 200 mesh, or 325 mesh, available from Imerys Refractory Minerals, Roswell, Georgia), and andalusite (e.g., Randalusite®, available from Fused Minerals, Roswell, Georgia).

[0019] Representative aluminas that may be utilized include calcined alumina (e.g., AC2-325 and AC2-325SG, sold by AluChem, Inc., Cincinnati, Ohio), thermally reactive alumina (e.g., AC17RG and AC19RG, sold by AluChem, Inc., Cincinnati, Ohio), reactive alumina (e.g., P172SB, sold by Alteo, Gardanne, France), tabular alumina (e.g., AC99, sold by AluChem, Inc., Cincinnati, Ohio), bauxite (e.g., RD-88, sold by Great Lake Minerals), and fused alumina sold by Imerys Fused Minerals of Greeneville, TN and FX Minerals Group of Newell, WV.

[0020] Exemplary silicon carbide that may be utilized includes silicon carbide having a particle size finer than 3 mesh, sold by ElectroAbrasives, Buffalo, New York.

[0021] Representative zirconia-containing raw materials include zircon powder and zirconia alumina silicate (e.g., DURAMUL® ZR, sold by Washington Mills) and dry-ground zircon finer than 3 mesh (e.g., 200 mesh, 325 mesh, 400 mesh, 600 mesh, sold by Continental Mineral Processing, Cincinnati, Ohio).

[0022] Magnesium-aluminum spinels that may be utilized include Spinel AR78 (a high alumina content spinel, 78% Al2O3, sold by Almatis, Inc.).

[0023] Representative silica fumes include NS-950 and NS-980 sold by Technical Silica Co., Atlanta, Georgia; a representative fused silica is Teco-Sil® fused silica sold by Imerys Refractory Materials of Greeneville, Tenn.; and a representative silica sand (crystalline silica) is sold by US Silica Company of Katy, Texas.

[0024] Depending on the application requirements, virtually any additive conventionally used in refractory materials can be satisfactorily used in the particulate refractory material of the present application. Optional additives include, for example, dispersants, coagulants including set time accelerators and set time retarders, flocculating agents, deflocculating agents, plasticizers, colorants, foaming agents, water retention agents, anti-settling agents, preservatives, etc. The particulate additives may also include ceramic and / or polymer fibrous materials. All additives present in the particulate material are preferably used in a total amount of up to about 15 wt. %, e.g., about 0.01 wt. % to about 15 wt. %, or more typically about 0.02 wt. % to about 10 wt. %, based on the total weight of the particulate high ε refractory material product.

[0025] The fire-resistant substrate of the present application necessarily contains a high-ε pigment in an amount sufficient to impart the desired high ε to the fire-resistant material upon curing. Virtually any high-ε pigment conventionally used in fire-resistant coating applications can be similarly utilized in the fire-resistant material of the present application. Pigments that, when incorporated into the fire-resistant material, impart the ability to emit broadband radiant energy upon curing, e.g., impart a "black body" effect to the cured fire-resistant material, are preferred. In certain embodiments, the high-ε pigment is incorporated into the fire-resistant material in an amount sufficient to, for example, cause the fire-resistant material to emit radiant energy at wavelengths from about 0.1 μm up to about 3.0 μm upon curing.

[0026] Preferred for use as high-ε pigments in the particulate material product embodiments disclosed herein are inorganic, high-temperature, inorganic metal oxides or carbides that impart broadband emissivity to the cured refractory material as described above. Particularly preferred are oxides of chromium, tin, iron (especially black iron oxide), and cerium. For example, suitable high-ε pigments include iron oxide pigments, chromium-iron black pigments, cadmium-chromium-iron-nickel black pigments, nickel-manganese-iron-chrome black pigments, chrome green pigments, iron-cobalt-chrome black pigments, iron-chrome black pigments, and iron-cobalt-chrome black pigments. Representative high-ε pigments are further disclosed in U.S. Pat. Nos. 9,499,677 and 10,400,150, the entire contents of which are expressly incorporated herein by reference.

[0027] Commercially available high ε pigments include Pigments BK-5099, BK-4799, R-3098, and YLO-2288D (sold by Brenntag Specialties, Reading, PA); Cerdec 41776A Black Pigment; Cerdec 41117A Black Pigment; Cerdec 10333 Black Pigment; Chrome Oxide (G4099) (sold by Harcros, Kansas City, KS); Black Pigment 6600 (sold by Mason Color Works, East Liverpool, OH); Pigments 1606 and 1607 (sold by Ceramic Color & Chemical, New Brighton, PA); chromite powder (sold by American Minerals); and iron cobalt chromite black spinel (PBK27) (sold by Ferro, Mayfield Heights, OH). A specific commercially available high ε pigment that can be successfully used in the practice of this invention is LANOX® 8303T Hi-Temp Black Iron Oxide by Lansco Colors of Pearl River, New York.

[0028] Preferably, the high ε pigment is present in the present particulate refractory material product in an amount sufficient to achieve an emissivity (ε) of greater than about 0.80, preferably from about 0.80 to about 0.95, and more preferably from about 0.90 to about 0.93. Specifically, the high ε pigment is present in the present particulate refractory material product in an amount up to about 20 wt %, e.g., from about 2 wt % to about 20 wt %, or more typically from about 3 wt % to about 10 wt %, and most preferably from about 4 wt % to about 8 wt % (e.g., from about 6 wt % to about 8 wt %), based on the total weight of the particulate high ε refractory material product.

[0029] The addition of high ε pigments improves the D of particulate refractory substrates. pst This is likely to adversely affect the final particle size distribution (D psf ) is the D of the fire-resistant substrates described so far. pst According to a preferred embodiment, such resetting or adjustment of the particle size distribution is performed after the addition of the high ε pigment to achieve a D of the final particulate refractory material product. psf is the granular refractory substrate D pst This is accomplished by adding a particulate refractory sizing component in an amount to reset the particle size distribution to be substantially the same as

[0030] The particle size distribution adjusting component must not only meet the particle size distribution requirements described above, but also not substantially impair the broadband radiation effect achieved by adding the high ε pigment. Representative preferred particle size distribution adjusting components include inorganic metal oxides, such as brown and / or white fused alumina and silicon carbide. Brown fused alumina is particularly preferred. Even with the addition of the particle size distribution adjusting component, it may still be necessary to slightly adjust the amount of one or more components present in the refractory base material.

[0031] The particle size distribution adjusting component typically has an average particle size distribution of +30 mesh = up to 10%, -30 / +40 mesh = 5-15%, -40 / +70 mesh = 20-50%, -70 / +100 mesh = 10-20 mesh, -100 / +140 mesh = 5-15%, and -140 / +325 mesh = 20-30%. The particle size distribution adjusting component is typically present in the particulate refractory material of the present application in an amount of up to about 20% by weight, for example, about 4% by weight to about 20% by weight, or more typically about 6% by weight to about 12% by weight (e.g., about 8% by weight to about 10% by weight), based on the total weight of the particulate high ε refractory material product.

[0032] To prepare a dry mix for the refractory material product, the necessary particulate ingredients, including the refractory base material and the high-ε pigment, may be dry-mixed using a conventional refractory mixer. If necessary, particle size adjusting ingredients may be added simultaneously or separately to the refractory base material and the high-ε pigment. Water is then added to the dry mix to prepare an aqueous castable wet mix with the desired flow characteristics. Specifically, the above-mentioned D pt The dry mix of the refractory material product having the formula (I) is mixed with sufficient water so that the resulting slurry exhibits a tap flow in accordance with ASTM Standard C1445-99 of about 15% to about 80%, more preferably about 15% to about 50%, e.g., about 20% to about 35%. The castable wet mix is then subsequently poured into a mold and allowed to harden to form a refractory structure or component.

[0033] The high ε fire-resistant material product of the present application may also be formed into a fire-resistant slurry or insulating foam. Thus, the fire-resistant slurry or insulating foam may be prepared by first combining particulate ingredients, including the high ε pigment, to form a dry mixture as previously described. Water may then be added to the dry mixture to prepare an aqueous slurry, which may be used in this form for certain applications. The slurry may then be combined with a conventional foaming material to form the fire-resistant insulating foam. The fire-resistant insulating foam may then be cured and hardened. Examples of conventional foaming materials include FM160® foam from Drexel Chemical Company of Memphis, Tenn.

[0034] The following non-limiting examples provide further understanding of specific embodiments of the present invention. [Example]

[0035] Example 1 The dry-mix formulation shown in Table 1 was utilized, using a conventional particulate refractory material as the substrate (WalMaxXx® 60M, approximately 60 wt. % mullite-based alumina, an ultra-low cement content castable conventional refractory material sold by Wahl Refractory Solutions of Fremont, Ohio) and a black iron oxide pigment (Lanox® 8303T Hi-Temp Black Iron Oxide sold by Lansco Colors of Pearl River, NY) as the high-ε pigment.

[0036] [Table 1]

[0037] Next, a dry mix of the particulate components shown in Table 1 was mixed with water to form a slurry with a tap flow (ASTM C1445-99) of about 25% to about 30% to prepare a castable wet mix. 3and cured at approximately 700°F (371°C). The resulting test samples were visually examined for color by comparing them to black bodies of samples formed with Formulations F3-F5 that were deemed acceptable for their black color.

[0038] Example 2 The sample from Formulation F4 in Example 1 was further exposed to a high temperature of 2200°F (1204°C). The sample was visually inspected after 5 hours and 100 hours of high temperature exposure and was determined to have maintained its black color.

[0039] Example 3 In preparing the slurries in Example 1, it was found that more water was required to form a suitable flowable slurry for each of Formulations F2-F5 compared to the base refractory material of Formulation F1. The need for additional water was due to the target particle size distribution (D pst ) was not equivalent to the particle size distribution of Formulations F2-F5. The amounts of ingredients in the refractory base material were adjusted by adding approximately 9 wt. % (based on the total weight of the formulation) of brown fused alumina as a particle size distribution adjusting component. Compared to Formulation F1, Formulations F2-F5 required essentially equivalent but slightly higher amounts of water (i.e., 6.0-6.5 wt. %, viz., 5.5-6.0 wt. %). This essentially equivalent amount of water required after particle size distribution adjustment indicates that the particle size distribution of Formulations F2-F5 is not equivalent to the D of the refractory base material of Formulation 1. pst The court determined that the amount of the tax benefit was adjusted to be substantially equivalent to the amount of the tax benefit.

[0040] Example 4 Formulation F4 was also evaluated for the time the castable wet mix could be worked before hardening. It was found that formulation F4 was well workable for 1 to about 2.5 hours after adding water to the dry mix. Formulation F4 was not workable after about 3 hours and hardened in less than about 4.5 hours.

[0041] While reference has been made to particular embodiments of the invention, various modifications within the skill of those in the art can be envisioned. It is therefore understood that the invention is not limited to the disclosed embodiments, but on the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. The following claims as originally filed in this application are appended as embodiments. [1] (a) a particulate refractory substrate comprising at least one particulate binder material, at least one particulate refractory raw filler material, and, optionally, at least one refractory additive; and (b) a high-ε pigment in an amount sufficient to impart a high-emissivity (high-ε) characteristic of at least 0.80 to the fire-resistant product upon curing; A particulate high-ε refractory product comprising a mixture of: [2] The final particle size distribution (D psf ) is a predetermined target particle size distribution (D pst ) The granular high ε refractory product according to [1], which is substantially equal to [3] The product adjusts the particle size distribution to psf The particulate high ε refractory product according to [2], further comprising a particle size distribution adjusting component in an amount sufficient to achieve the above. [4] The particulate high ε refractory product according to [3], wherein the particle size distribution adjusting component is at least one inorganic metal oxide selected from the group consisting of brown fused alumina, white fused alumina, and silicon carbide. [5] The particulate high ε refractory product according to [3], wherein the particle size distribution adjusting component is present in an amount of up to about 20% by weight based on the total weight of the particulate high ε refractory material product. [6] D above pst and D of said fire-resistant product psf , and the particle size distribution of each is 4 mesh<2%; 10 mesh = 23% ± 5%; 20 mesh = 42% ± 5%; 100 mesh=58%±5%; 200 mesh = 64% ± 5%, and -325 mesh = 32% ± 5% The granular high ε refractory product according to [2], [7] The particulate high ε refractory product according to [1], wherein the particulate binder material is present in the refractory base material in an amount of 2 wt % to about 30 wt % based on the total weight of the particulate high ε refractory material product. [8] The particulate high ε refractory product according to [1], wherein the refractory raw filler material is present in the refractory base material in an amount of 50% by weight to about 99% by weight, based on the total weight of the particulate high ε refractory material product. [9] The particulate high ε refractory product according to [1], wherein the refractory raw material filler contains at least one particulate refractory material selected from the group consisting of alumina silicate, alumina, silicon carbide, zirconia-containing raw material, magnesium-aluminum spinel, silica fume, burnt flint, fused silica, and silica sand.

[10] The particulate high ε refractory product according to [1], wherein the average particle size of the refractory raw material filler is finer than 3 mesh.

[11] The granular high ε fire-resistant product according to [1], wherein the at least one fire-resistant additive is selected from the group consisting of dispersants, coagulants including set time accelerators and set time retarders, flocculants, deflocculating agents, plasticizers, colorants, foaming agents, water-retaining agents, anti-settling agents, and preservatives.

[12] The particulate high ε refractory product according to [1], wherein the at least one refractory additive is present in an amount of up to about 15 wt % based on the total weight of the particulate high ε refractory material product.

[13] The particulate high-ε fire-resistant product of [1], wherein the high-ε pigment is present in an amount sufficient to impart an emissivity of about 0.80 to about 0.95 to the product upon curing.

[14] The particulate high-ε fire-resistant product of

[13] , wherein the high-ε pigment is present in an amount sufficient to impart an emissivity of about 0.90 to about 0.93 to the product upon curing.

[15] The particulate high ε fire-resistant product according to

[13] , wherein the high ε pigment is present in an amount of up to about 20% by weight based on the total weight of the particulate high ε fire-resistant product.

[16] The particulate high-ε fire-resistant product according to

[13] , wherein the high-ε pigment is present in an amount of about 2% by weight to about 20% by weight based on the total weight of the particulate high-ε fire-resistant product.

[17] The particulate high-ε fire-resistant product according to

[16] , wherein the high-ε pigment is present in an amount of about 3% by weight to about 10% by weight based on the total weight of the particulate high-ε fire-resistant product.

[18] The particulate high-ε fire-resistant product according to

[16] , wherein the high-ε pigment is present in an amount of about 4% by weight to about 6% by weight based on the total weight of the particulate high-ε fire-resistant product.

[19] A castable refractory wet mix comprising the particulate high ε refractory product according to [1] and water.

[20] A hardened refractory part comprising the hardened residue of a castable refractory wet mix as described in

[19] .

[21] A method of forming a particulate high ε refractory product according to [1], comprising dry-mixing the particulate refractory substrate with a high ε pigment in an amount sufficient to impart a high ε characteristic of at least 0.80 to the refractory product upon curing.

[22] The target particle size distribution (D pst ) to substantially match the final particle size distribution (D psf

[21] The method of

[21] , further comprising adding a particle size distribution adjusting component to the dry mixture of the fire-resistant substrate and the high ε pigment sufficient to adjust the particle size distribution.

[23] A method of forming a castable refractory wet mix, comprising adding water to the particulate high ε refractory product of [1].

[24] A method for forming an aqueous refractory slurry, comprising dispersing the particulate high ε refractory product according to [1] in water.

[25] (i) forming an aqueous refractory slurry according to

[24] ; and (ii) combining the aqueous fire-resistant slurry with an aqueous blowing agent to prepare a fire-resistant insulating foam material. 1. A method for forming a fire resistant insulating foam material, comprising:

Claims

1. A particulate high-emissivity (high ε) fire-resistant product having a final particle size distribution (D psf ), (a) a particulate refractory substrate having a predetermined target particle size distribution (D pst ), based on the total weight of the particulate high ε refractory product: (a1) 2 to 30 wt. % of at least one particulate binder material selected from the group consisting of calcium aluminate cement, hydratable alumina, phosphate-based binders, sodium silicate, colloidal silica, and colloidal alumina; (a2) 50 to 95 wt. % of at least one particulate refractory raw filler material selected from the group consisting of alumina silicates, alumina, silicon carbide, zirconia-containing raw materials, magnesium-aluminum spinel, silica fume, burnt flint, fused silica, and silica sand; a particulate refractory substrate comprising a mixture of: (b) a high-ε inorganic high-temperature pigment uniformly distributed in said refractory substrate component (a), selected from the group consisting of metal oxides or metal carbides, present in an amount of 2% to 20% by weight, based on the total weight of the particulate high-ε refractory product, and present in an amount sufficient to (i) impart an emissivity (ε) of at least 0.80 to said refractory product upon cure, and (ii) modify the D psf of said particulate high-ε refractory product; and (c) a particle size distribution modifying component selected from the group consisting of brown fused alumina, white fused alumina, and silicon carbide, present in an amount sufficient to modify the particle size distribution of components (a), (b), and (c) so that the D psf of the particulate high-ε refractory product, as modified by the high-ε inorganic high-temperature pigment component (b), is reset such that the D psf of the particulate high-ε refractory product is substantially the same as the D pst of the particulate refractory substrate component (a); A particulate high-ε refractory product comprising a mixture of:

2. A particulate high ε fire-resistant product as described in claim 1, wherein the particulate fire-resistant substrate contains (a3) at least one fire-resistant additive.

3. 3. The particulate high ε refractory product according to claim 1 or 2, wherein the particle size distribution adjusting component is present in an amount of up to 20% by weight, based on the total weight of the particulate high ε refractory material product.

4. The above D ｐｓｔ and D of said fire-resistant product ｐｓｆ , and the particle size distribution of each is 4 mesh < 2%; 10 mesh = 23% ± 5%; 20 mesh = 42% ± 5%; 100 mesh = 58% ± 5%; 200 mesh = 64% ± 5%, and -325 mesh = 32% ± 5% 3. The particulate high ε refractory product according to claim 1 or 2, wherein

5. 3. The particulate high ε refractory product according to claim 1 or 2, wherein the particulate binder material is present in the refractory substrate in an amount of 2% by weight to 10% by weight, based on the total weight of the particulate high ε refractory material product.

6. 2. The particulate high ε refractory product according to claim 1, wherein the refractory raw filler material is present in the refractory substrate in an amount of 75% by weight to 95% by weight, based on the total weight of the particulate high ε refractory material product.

7. 2. The particulate high ε refractory product of claim 1, wherein the average particle size of the refractory raw filler is finer than 3 mesh.

8. 3. The granular high ε fire-resistant product according to claim 1 or 2, wherein the at least one fire-resistant additive is selected from the group consisting of dispersants, coagulants including set time accelerators and set time retarders, flocculating agents, deflocculating agents, plasticizers, colorants, foaming agents, water-retaining agents, anti-settling agents and preservatives.

9. 3. A particulate high ε refractory product according to claim 1 or 2, wherein said at least one refractory additive is present in a maximum amount of 15% by weight relative to the total weight of the particulate high ε refractory material product.

10. 3. The particulate high ε refractory product of claim 1 or 2, wherein said high ε inorganic high temperature pigment is present in an amount sufficient to impart an emissivity of 0.80 to 0.95 to said product upon curing.

11. 11. The particulate high ε refractory product of claim 10, wherein said high ε inorganic high temperature pigment is present in an amount sufficient to impart an emissivity of 0.90 to 0.93 to said product upon curing.

12. 3. The particulate high-ε refractory product according to claim 1 or 2, wherein said high-ε inorganic high-temperature pigment is present in an amount of 3% to 10% by weight relative to the total weight of the particulate high-ε refractory product.

13. 3. The particulate high-ε refractory product according to claim 1 or 2, wherein said high-ε inorganic high-temperature pigment is present in an amount of 4% to 6% by weight relative to the total weight of the particulate high-ε refractory product.

14. A castable refractory wet mix comprising the particulate high ε refractory product of claim 1 or 2 and water.

15. 15. A cured refractory part comprised of the cured residue of the castable refractory wet mix of claim 14.

16. 10. A method for forming the particulate high ε refractory product of claim 1, comprising: dry blending said particulate refractory substrate with said high ε inorganic high temperature pigment in an amount sufficient to impart a high ε characteristic of at least 0.80 to said refractory product upon cure; adding a particle size distribution adjusting component to a dry mixture of the refractory substrate and the high ε inorganic high temperature pigment sufficient to adjust the final particle size distribution (D psf ) of the high ε refractory product to substantially match the target particle size distribution (D pst ) of the refractory substrate; Including, The particulate refractory base material is, based on the total weight of the particulate high ε refractory product, (a1) 2 to 30 wt. % of at least one particulate binder material selected from the group consisting of calcium aluminate cement, hydratable alumina, phosphate-based binders, sodium silicate, colloidal silica, and colloidal alumina; (a2) 50 to 95 wt. % of at least one particulate refractory raw filler material selected from the group consisting of alumina silicates, alumina, silicon carbide, zirconia-containing raw materials, magnesium-aluminum spinel, silica fume, burnt flint, fused silica, and silica sand; a mixture of the high ε inorganic high temperature pigment is selected from the group consisting of metal oxides or metal carbides, and the high ε inorganic high temperature pigment is present in an amount of 2% to 20% by weight based on the total weight of the particulate high ε refractory product; The method wherein the particle size distribution modifying component is selected from the group consisting of brown fused alumina, white fused alumina, and silicon carbide.

17. 3. A method of forming a castable refractory wet mix comprising adding water to the particulate high ε refractory product of claim 1 or 2.

18. 3. A method for forming an aqueous refractory slurry comprising dispersing the particulate high ε refractory product of claim 1 or 2 in water.

19. (i) forming an aqueous refractory slurry according to claim 18; and (ii) combining the aqueous fire-resistant slurry with an aqueous blowing agent to prepare a fire-resistant insulating foam material.

1. A method for forming a fire resistant insulating foam material, comprising:

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