Compositions for the water side treatment of high heat flux copper molds

Abstract

A composition for inhibiting oxidation and corrosion of a copper surface and / or removing oxidation and corrosion byproducts on a copper surface contains at least one copper corrosion inhibiting compound, at least one polymer dispersant, and at least one chelating agent, wherein the at least one chelating agent is included in the composition in an amount of from 0.1% to 10% by weight of the composition. The composition is applied to the copper surface, either as is or in a solution with purified water, and thereby inhibits and / or cleans corrosion such as copper oxide from the copper surface. The composition may be included in cooling water provided to a copper mold in a continuous casting process, or in an offline cleaning or storage campaign.

Description

BACKGROUND

[0001] The present invention relates to a composition for an additive to include in cooling water, particularly cooling water cycled through a copper mold used in, for example, continuous casting of a metal such as steel.

[0002] Conventionally, as an operation method of a continuous casting machine, there is known a continuous casting process in which molten metal such as molten steel is poured from a tundish into a mold, and the poured molten metal is partially cooled by the mold to solidify at least the surface of the molten metal. The mold is typically comprised of plates of a copper material when the metal being cast is steel. The cooling includes the use of cooling water fed through an open or closed loop system of pipes embedded in the mold. The cooling within the mold removes heat from the molten metal to solidify the surface of the molten metal. A semi-solidified solid product is withdrawn from the lower portion of the mold by a drawing roll, and subsequently a completely solidified solid product is produced through the use of further cooling within the machine by, for example, spray cooling.

[0003] In the continuous casting process, control of the cooling rate (i.e., heat extraction rate) through the mold is significant and requires precision control. If heat is extracted too slowly from the molten metal in the mold, a decrease in the thickness of the solidified shell of the solid product at the lower end of the mold, and an uneven distribution of the thickness of the solidified shell, will occur. As a result, a so-called breakout may occur in which the solidified shell is broken to cause leakage of molten metal upon exiting the mold. When a breakout occurs, a long down time occurs to clean and repair the continuous casting machine, and thus productivity is significantly deteriorated. On the other hand, if heat is extracted too rapidly from the molten metal while in the mold, the metal will harden too significantly before exiting the machine, and thus may become stuck within the continuous molding machine, which again causes a long down time for cleaning and repair of the continuous casting machine. In addition, inconsistent or nonuniform heat transfer across the mold can also lead to other defects in the cast product.

[0004] While the heat extraction rate can typically be sufficiently managed through control over the heat flux, cooling water flow, cooling water temperature, and the casting speed rate through the machine, other factors can adversely affect the cooling rate through the mold. One such factor is corrosion of the mold material, for example the formation of oxides on the cooling water side, cold face, surface of the mold.

[0005] Corrosion is caused by metals attempting to return to their natural state. Corrosion and byproducts thereof can be present in many forms, including localized or pitting, uniform metal loss, bi-metallic, galvanic, underdeposit, and microbiologically-induced corrosion (MIC). The process starts when surface irregularities, stresses, or compositional differences result in the formation of a corrosion cell (anode and cathode). Once started, corrosion at the anode causes metal to be released into the system or redeposited locally. As corrosion and byproducts precipitate on critical heat transfer devices and insulate the metals, heat transfer efficiency loss occurs.

[0006] Copper and its alloys (all referred to generally as “yellow metals”) are conventionally used as a mold material in continuous casting to form cast steel. Copper alloys are known to be susceptible to corrosion that can occur as a result of exposure of the mold surface at high temperatures to oxygenated water. In this context, copper oxidation causes the base material to change, e.g., oxidize, which also alters the thermal conductivity properties of the mold. The subsequent non-uniform heat removal alters the heat extraction rate through the mold and can lead to steel defects and increased copper mold wear.

[0007] U.S. Pat. No. 5,128,065 describes a method for inhibiting the corrosion of copper or copper-bearing metals in contact with an aggressive aqueous environment comprising brackish water, salt water, or water containing brine or sulfides by forming a passive film on the surface of the metals comprising generating a water soluble copper complex consisting essentially of adding to the aggressive aqueous environment a sufficient amount for the purpose of a copper corrosion inhibitor and a chelant selected from the group consisting of ethylenediamine tetraacetic acid, the mono- or triesters of ethylenediamine tetraacetic acid, ethylenediamine mono or tricarboxylic acid, nitrilo triacetic acid or monoester thereof, citric acid, its salts and derivatives thereof, tartaric acid, its salts and derivatives thereof and dialkyldithiocarbamates.

[0008] U.S. Pat. No. 11,760,666 describes a method to reduce or eliminate N-heerocycles or adsorbable organic halides (AOX), the method providing one or more environmentally benign chelators (EBCs) to an aqueous cooling system.

[0009] There is a demand for an improved methodology for not only inhibiting corrosion and oxidation of the copper surface in a first instance, but also for cleaning the copper surface of any oxidation and corrosion byproducts that may occur.SUMMARY

[0010] The present application relates to a composition comprising at least one copper corrosion inhibiting compound, at least one polymer dispersant, and at least one chelating agent, wherein the at least one chelating agent is included in the composition in an amount of from about 0.1% to about 10% by weight of the composition. This composition, when applied to the surface of a copper material either as is or in solution with purified water, can not only inhibit corrosion and oxidation of the copper, but can also clean a copper surface the composition contacts of any corrosion / oxidation that has formed thereon.

[0011] The composition can find particular utility as an additive for cooling water supplied to a copper mold in a continuous casting process, for example a continuous casting process forming cast steel slabs. A particularly preferred use is in a closed loop system with a copper / yellow metal mold having high heat flux, the composition functioning to keep the mold clean and free of oxidation and corrosion byproduct deposition.

[0012] Thus, the present application also relates to a method of inhibiting oxidation and corrosion of a copper surface and / or removing oxidation and corrosion byproduct fouling on a copper surface, comprising applying the composition comprising at least one copper corrosion inhibiting compound, at least one polymer dispersant, and at least one chelating agent to the copper surface.

[0013] Also provided is a method of forming a cast metal in a continuous casting process, comprising providing molten metal into a continuous casting machine including a copper mold, cooling the molten metal as the molten metal passes through the copper mold, the cooling comprising adding the composition of claim 1 into cooling water fed to a surface of the copper mold away from the molten metal, the cooling water contacting the surface of the copper mold and thereby inhibiting oxidation and corrosion of the surface and / or removing oxidation and corrosion byproducts from the surface, and maintaining predetermined heat transfer rates to solidify molten metal exiting the copper mold to form a cast metal free of heat transfer related defects.DETAILED DESCRIPTION OF EMBODIMENTS

[0014] Although specific embodiments are described herein, the scope of the invention and claims is not limited to only those specific embodiments. The scope of the invention is defined by the following claims and any equivalents therein. As will be appreciated by one skilled in the art, aspects of the present disclosure may be embodied as an apparatus, system or method.

[0015] The terms “comprise(s),”“comprising,”“include(s),”“including,”“having,”“has,”“contain(s),”“containing,” and variants thereof, as used herein, are open-ended transitional phrases, terms, or words that are meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The singular forms “a”, “and”, and “the” include plural references unless the context clearly dictates otherwise. Where the term “comprising” is used, the present disclosure also contemplates other embodiments “comprising”, “consisting of”, or “consisting essentially of” elements presented herein, whether explicitly set forth or not.

[0016] Any numerical range recited herein includes all values from the lower value to the upper value. For example, if a concentration range is stated as 1% to 50%, it is intended that values such as 2% to 40%, 10% to 30%, or 1% to 3%, etc., are expressly enumerated in this specification. These are only examples of what is specifically intended, and all possible combinations of numerical values between and including the lowest value and the highest value enumerated are to be considered to be expressly stated in this application.

[0017] The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (for example, it includes at least the degree of error associated with the measurement of the particular quantity). The modifier “about” should also be considered as disclosing the range defined by the absolute values of the two endpoints. For example, the expression “from about 2 to about 4” also discloses the range “from 2 to 4.” The term “about” may refer to plus or minus 10% of the indicated number. For example, “about 10%” may indicate a range of 9% to 11%, and “about 1” may mean from 0.9-1.1. Other meanings of “about” may be apparent from the context, such as rounding off, so, for example “about 1” may also mean from 0.5 to 1.4.

[0018] In general, the amount of a component in a composition as disclosed herein is expressed “by weight” which refers to the percentage of the component's weight in the total weight of the composition. Unless indicated otherwise, all concentrations are expressed as weight percentage concentrations.

[0019] The composition described herein comprises at least one copper corrosion inhibiting compound, at least one polymer dispersant, and at least one chelating agent. The at least one chelating agent is desirably present in the composition in an amount of from 0.1% to 10% by weight of the composition. Applicant has found that the inclusion of the chelating agent achieves a synergistic improvement in corrosion inhibition and removal when applied to a copper material.

[0020] The at least one copper corrosion inhibiting compound can be any suitable compound capable of inhibiting corrosion on the surface of the copper material. Suitable examples for use in the composition include azoles such as tolyltriazole (TTA), benzotriazole (BZT), methylbenzotriazole (MBT), halogen stable azole, and mercaptobenzothiazole, including salts thereof. Heterocyclic non-triazole compounds as described in App. No. 63 / 541,425, incorporated herein by reference in its entirety, may also be used as a copper corrosion inhibiting compound. The copper corrosion inhibiting compound can be used alone or in combination of two or more.

[0021] A preferred copper corrosion inhibiting compound for use herein includes sodium tolyltriazole, benzotriazole, mercaptobenzothiazole, any form of a halogenated azole, and combinations thereof.

[0022] The copper corrosion inhibiting compound may be included in the composition in an amount of from about 0.1% to about 50% by weight of the composition, preferably from about 0.1% to about 30%, or from about 0.1% to about 10%, by weight of the composition.

[0023] The at least one chelating agent may include any common chelating agents, for example including an aminopolycarboxylic acid, a hydroxcarboxylic acid such as citric acid and glycolic acid, and polyhydroxycarboxylic acids / sugar acids such as glucaric acid, glucoheptonate, and gluconic acid), and mixtures thereof. Preferred chelating agents are aminopolycarboxylic acids including, for example, ethylenediaminetetraacetic acid (EDTA), 1-glutamic acid, N,N-diacetic acid (GLDA), diethylenetriaminepentaacetic acid (DTPA) and methylglycinediacetic acid (MGDA). The chelating agent can be used alone or in combination of two or more.

[0024] The at least one chelating agent may be included in the composition in an amount of from about 0.01 to about 20% by weight of the composition.

[0025] The chelating agents appear to both solubilize and clean the copper surface.

[0026] The composition also contains at least one polymer dispersant.

[0027] The polymer of the polymer dispersant refers to a macromolecular chain comprising repeating units. The polymer can be a homopolymer of the same repeating monomeric units, or can be a copolymer of one or more, such as two, three (e.g., terpolymers), four (e.g., quad polymers) or more different monomeric units in the chain.

[0028] The monomeric units making up the polymer chain are not particularly limited, and may include monomeric units from, for example, vinyl sulfonic acid, or vinyl sulfonates salts, vinyl phosphonic acid, or vinyl phosphonates salts, vinylidene diphosphonic acid, or salts thereof, acrylic acid, methacrylic acid, vinyl acetate, vinyl alcohol, unsaturated mono- or di-carboxylic acids or anhydrides, such as maleic anhydride, maleic acid, fumaric acid, itaconic acid, aconitic acid, mesaconic acid, citraconic acid, crotonic acid isocrotonic acid, angelic acid, tiglic acid, and the like, vinyl chloride, styrene-p-sulfonic acid, or styrene sulfonates salts, acrylamido-2-methylpropanesulfonic acid (AMPS), hydroxyphosphonoacetic acid (HPA), hypophosphorus acids such as H3PO3, giving units of formula —PO(OH)—, acrylamides, propargyl alcohol having formula HC═C—CH2—OH, butyr-1,4-diol, and the like.

[0029] As described in U.S. Pat. No. 7,087,189 (incorporated herein by reference in its entirety), the polymer may include at least one monomer unit from each of dicarboxylic acids, mono-carboxylic acids, nonionic monomers, and sulfonated or sulfated monomers. The dicarboxylic monomer is one or more ethylenically unsaturated monomer containing two carboxylic acid groups, and includes aliphatic, branched or cyclic dicarboxylic acids, the alkali or alkaline earth metal or ammonium salts thereof, and the anhydrides thereof. Examples of dicarboxylic acid monomers include, but are not limited to itaconic acid, maleic acid, and maleic anhydride, citraconic acid, mesaconic acid, glutaconic acid, aconitic acid, fumaric acid, and tricarboxy ethylene, or mixtures thereof. Preferred dicarboxylic acid monomers are maleic acid or maleic anhydride. The mono-carboxylic acid monomer is one or more ethylenically unsaturated monomers having a single carboxylic acid functionality and includes aliphatic, branched or cyclic, mono-carboxylic acids, and the alkali or alkaline earth metal or ammonium salts thereof. Examples of mono-carboxylic acid monomers includes acrylic acid, methacrylic acid, ethacrylic acid, alpha-chloro-acrylic acid, alpha-cyano acrylic acid, alpha-chloro-acrylic acid, alpha-cyano acrylic acid, beta methyl-acrylic acid (crotonic acid), alpha-phenyl acrylic acid, beta-acryloxy propionic acid, sorbic acid, alpha-chloro sorbic acid, angelic acid, cinnamic acid, p-chloro cinnamic acid, beta-styryl acrylic acid (1-carboxy-4-phenyl butadiene-1,3), and mixtures thereof. The non-ionic monomer is an ethylenically unsaturated nonionic monomer including monomers represented by the chemical structure R3-X1-(CR1R2)-(CH)═(CR7)-(CR8R9)-X2-R10, wherein n1 and n2 are independently 0 to 10; R1, R2, R8 and R9 are independently hydrogen, C1-C6 alkyl, or C1-C6 alkyl-substituted aryl; R7 is hydrogen, or C1-C6 alkyl; X1 and X2 are absent or are independently O, C—O, or hydrogen; R3 is absent or is C—OR4, OR4, NR5R6, C1-C18 alkyl or hydrogen, where R4 is C1-C18 alkyl or hydrogen and R5 and R6 are independently hydrogen, C1-C6 alkyl, or an alkyloxyether or alcohol; and R10 is absent or is C—OR11, OR11, NR12R13, C1-C18 alkyl, or hydrogen, where R11 is C1-C18 alkyl or hydrogen, R12 and R13 are independently hydrogen, C1 to C6 alkyl, or an alkyloxyether or alcohol, such as C1-C6 alkyl esters of (meth)acrylic acid and the alkali or alkaline earth metal or ammonium salts thereof, acrylamide and the C1-C6 alkyl-substituted acrylamides, the N-alkyl-substituted acrylamides and the N-alkanol-substituted acrylamides. The sulfonated or sulfated monomer is one or more ethylenically unsaturated monomers containing a sulfonate functionality, such as (meth)acrylamido methyl propane sulfonic acid, styrene sulfonic acid, acrylamido alkyl or aryl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, and salts thereof.

[0030] The polymer dispersant may be included in the composition in any suitable amount, for example in an amount of from about 0.1% to about 50% by weight of the composition, including from about 1% to about 30% by weight or about 5% to about 20% by weight of the composition.

[0031] In total, the composition may include the chelating agent and the polymer dispersant in amounts such that a concentration of the chelating agent and polymer dispersant is in the range of, for example, 1-1000 ppm, such as 1-500 ppm, in the composition or treatment fluid, during storage or service.

[0032] In addition to the foregoing, the composition may also include additional optional additives. One such additive is a buffer such as triethanolamine or borax. Fluorescent tracers such as PTSA (1,3,6,8-pyrenetetrasulfonic acid) or NDSA (naphthalene disulfonate) may also be present.

[0033] The composition can also include water, such as distilled water and / or deionized water or RO water or city / tap water. The composition may be a dry product, supplied and / or fed as such, i.e., contain 0% by weight of water, or may include from about 10% to about 90% by weight of water. If water is included, the components of the composition should all be sufficiently water soluble to not settle out of the composition. Note that the amounts of water indicated for the composition are prior to use of the composition in subsequent copper corrosion inhibition and / or removal, where the composition may be included in a solution with water for such treatment.

[0034] The composition may be formed in any suitable manner, for example by mixing together the various components of the composition.

[0035] The composition finds utility in inhibiting oxidation and corrosion of a copper surface and / or in removing, for example through cleaning, any and corrosion byproducts that do occur on a copper surface.

[0036] As the copper of the copper surface, any copper, i.e., copper containing material, may be used. The copper may be pure copper, a copper alloy, or a metal including a measurable amount of copper.

[0037] In preferred embodiments herein, the copper is in the form of a mold for a continuous casting machine. In such molds, cooling water is provided to the side of the copper mold opposite the side in contact with the molten metal, such as molten steel, in order to extract heat from the molten metal and mold, and thereby assist in the cooling process of the molten metal as it passes through the mold.

[0038] As noted earlier, the use of cooling water, while effective for heat extraction, can also cause corrosion, oxidation and byproduct fouling on the copper surface contacted by the cooling water. Such corrosion, oxidation and related byproduct fouling can be inhibited, and if it occurs can be cleaned and removed, by application of the compositions herein to the surface of the copper.

[0039] The application of the composition to the copper surface can be done at any suitable stage. For example, the composition can be applied to the copper surface upon formation of the mold from the copper and before use in a continuous molding machine. The composition can also be applied to the copper surface following a refurbishing cleaning of the mold removed from the machine and prior to re-installation. The composition may also be used during offline storage of the mold, for example during maintenance, a cleaning or refurbishing, of the mold prior to re-installation. As an example, the mold may be contained in a steel container, and the container filled with a treatment fluid that includes the composition. The treatment fluid can protect both the copper mold and the steel container, and in this regard the treatment fluid or composition can also include a steel corrosion inhibitor such as a nitrite compound.

[0040] In either case, the copper surface may be polished prior to application of the composition thereto. The composition can be applied as is, or the composition can be added to water, preferably purified water, to form a solution that is applied to the aforementioned copper surfaces. In these treatments, the composition or solution may be applied to the surface by any suitable method, such as by spraying, or the copper surface can be immersed in the composition or solution to soak.

[0041] For a solution, the composition can be added to a treatment solution in an amount of about 100 ppm to about 50000 ppm to process water.

[0042] In addition, when the mold is in use in a continuous molding machine, the surface of the copper mold exposed to the cooling water may be treated by including the composition in the cooling water, at a concentration the same as the treatment solution discussed above. The cooling water, which is preferably in a closed loop recirculating system, may be continuously monitored for the amount of the composition remaining therein, and continuously dosed with additional amounts of the composition to retain a substantially steady state amount of the composition in the cooling water fed to the mold.

[0043] In a method of forming a cast metal in a continuous casting process, molten metal is provided into a continuous casting machine including a copper mold, and cooling the molten metal as the molten metal passes through the copper mold. The cooling preferably includes adding the composition of the present application into cooling water fed to a surface of the copper mold away from the molten metal, the cooling water contacting the surface of the copper mold and thereby inhibiting oxidation and corrosion of the surface and / or removing oxidation and corrosion byproducts from the surface. In the process, predetermined heat transfer rates are able to be maintained in order to solidify the molten metal exiting the copper mold to form a cast metal free of heat transfer related defects.

[0044] The addition of a chelating agent may result in a synergistic boost in the copper corrosion inhibition performance of the composition, particularly compared to compositions simply containing additional copper corrosion inhibiting compounds or containing only polymer dispersants.

Examples

Embodiment Construction

[0014]Although specific embodiments are described herein, the scope of the invention and claims is not limited to only those specific embodiments. The scope of the invention is defined by the following claims and any equivalents therein. As will be appreciated by one skilled in the art, aspects of the present disclosure may be embodied as an apparatus, system or method.

[0015]The terms “comprise(s),”“comprising,”“include(s),”“including,”“having,”“has,”“contain(s),”“containing,” and variants thereof, as used herein, are open-ended transitional phrases, terms, or words that are meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The singular forms “a”, “and”, and “the” include plural references unless the context clearly dictates otherwise. Where the term “comprising” is used, the present disclosure also contemplates other embodiments “comprising”, “consisting of”, or “consisting essentially of” elements presented herein, whether explicit...

BACKGROUND

[0001] The present invention relates to a composition for an additive to include in cooling water, particularly cooling water cycled through a copper mold used in, for example, continuous casting of a metal such as steel.

[0002] Conventionally, as an operation method of a continuous casting machine, there is known a continuous casting process in which molten metal such as molten steel is poured from a tundish into a mold, and the poured molten metal is partially cooled by the mold to solidify at least the surface of the molten metal. The mold is typically comprised of plates of a copper material when the metal being cast is steel. The cooling includes the use of cooling water fed through an open or closed loop system of pipes embedded in the mold. The cooling within the mold removes heat from the molten metal to solidify the surface of the molten metal. A semi-solidified solid product is withdrawn from the lower portion of the mold by a drawing roll, and subsequently a completely solidified solid product is produced through the use of further cooling within the machine by, for example, spray cooling.

[0003] In the continuous casting process, control of the cooling rate (i.e., heat extraction rate) through the mold is significant and requires precision control. If heat is extracted too slowly from the molten metal in the mold, a decrease in the thickness of the solidified shell of the solid product at the lower end of the mold, and an uneven distribution of the thickness of the solidified shell, will occur. As a result, a so-called breakout may occur in which the solidified shell is broken to cause leakage of molten metal upon exiting the mold. When a breakout occurs, a long down time occurs to clean and repair the continuous casting machine, and thus productivity is significantly deteriorated. On the other hand, if heat is extracted too rapidly from the molten metal while in the mold, the metal will harden too significantly before exiting the machine, and thus may become stuck within the continuous molding machine, which again causes a long down time for cleaning and repair of the continuous casting machine. In addition, inconsistent or nonuniform heat transfer across the mold can also lead to other defects in the cast product.

[0004] While the heat extraction rate can typically be sufficiently managed through control over the heat flux, cooling water flow, cooling water temperature, and the casting speed rate through the machine, other factors can adversely affect the cooling rate through the mold. One such factor is corrosion of the mold material, for example the formation of oxides on the cooling water side, cold face, surface of the mold.

[0005] Corrosion is caused by metals attempting to return to their natural state. Corrosion and byproducts thereof can be present in many forms, including localized or pitting, uniform metal loss, bi-metallic, galvanic, underdeposit, and microbiologically-induced corrosion (MIC). The process starts when surface irregularities, stresses, or compositional differences result in the formation of a corrosion cell (anode and cathode). Once started, corrosion at the anode causes metal to be released into the system or redeposited locally. As corrosion and byproducts precipitate on critical heat transfer devices and insulate the metals, heat transfer efficiency loss occurs.

[0006] Copper and its alloys (all referred to generally as “yellow metals”) are conventionally used as a mold material in continuous casting to form cast steel. Copper alloys are known to be susceptible to corrosion that can occur as a result of exposure of the mold surface at high temperatures to oxygenated water. In this context, copper oxidation causes the base material to change, e.g., oxidize, which also alters the thermal conductivity properties of the mold. The subsequent non-uniform heat removal alters the heat extraction rate through the mold and can lead to steel defects and increased copper mold wear.

[0007] U.S. Pat. No. 5,128,065 describes a method for inhibiting the corrosion of copper or copper-bearing metals in contact with an aggressive aqueous environment comprising brackish water, salt water, or water containing brine or sulfides by forming a passive film on the surface of the metals comprising generating a water soluble copper complex consisting essentially of adding to the aggressive aqueous environment a sufficient amount for the purpose of a copper corrosion inhibitor and a chelant selected from the group consisting of ethylenediamine tetraacetic acid, the mono- or triesters of ethylenediamine tetraacetic acid, ethylenediamine mono or tricarboxylic acid, nitrilo triacetic acid or monoester thereof, citric acid, its salts and derivatives thereof, tartaric acid, its salts and derivatives thereof and dialkyldithiocarbamates.

[0008] U.S. Pat. No. 11,760,666 describes a method to reduce or eliminate N-heerocycles or adsorbable organic halides (AOX), the method providing one or more environmentally benign chelators (EBCs) to an aqueous cooling system.

[0009] There is a demand for an improved methodology for not only inhibiting corrosion and oxidation of the copper surface in a first instance, but also for cleaning the copper surface of any oxidation and corrosion byproducts that may occur.SUMMARY

[0010] The present application relates to a composition comprising at least one copper corrosion inhibiting compound, at least one polymer dispersant, and at least one chelating agent, wherein the at least one chelating agent is included in the composition in an amount of from about 0.1% to about 10% by weight of the composition. This composition, when applied to the surface of a copper material either as is or in solution with purified water, can not only inhibit corrosion and oxidation of the copper, but can also clean a copper surface the composition contacts of any corrosion / oxidation that has formed thereon.

[0011] The composition can find particular utility as an additive for cooling water supplied to a copper mold in a continuous casting process, for example a continuous casting process forming cast steel slabs. A particularly preferred use is in a closed loop system with a copper / yellow metal mold having high heat flux, the composition functioning to keep the mold clean and free of oxidation and corrosion byproduct deposition.

[0012] Thus, the present application also relates to a method of inhibiting oxidation and corrosion of a copper surface and / or removing oxidation and corrosion byproduct fouling on a copper surface, comprising applying the composition comprising at least one copper corrosion inhibiting compound, at least one polymer dispersant, and at least one chelating agent to the copper surface.

[0013] Also provided is a method of forming a cast metal in a continuous casting process, comprising providing molten metal into a continuous casting machine including a copper mold, cooling the molten metal as the molten metal passes through the copper mold, the cooling comprising adding the composition of claim 1 into cooling water fed to a surface of the copper mold away from the molten metal, the cooling water contacting the surface of the copper mold and thereby inhibiting oxidation and corrosion of the surface and / or removing oxidation and corrosion byproducts from the surface, and maintaining predetermined heat transfer rates to solidify molten metal exiting the copper mold to form a cast metal free of heat transfer related defects.DETAILED DESCRIPTION OF EMBODIMENTS

[0014] Although specific embodiments are described herein, the scope of the invention and claims is not limited to only those specific embodiments. The scope of the invention is defined by the following claims and any equivalents therein. As will be appreciated by one skilled in the art, aspects of the present disclosure may be embodied as an apparatus, system or method.

[0015] The terms “comprise(s),”“comprising,”“include(s),”“including,”“having,”“has,”“contain(s),”“containing,” and variants thereof, as used herein, are open-ended transitional phrases, terms, or words that are meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The singular forms “a”, “and”, and “the” include plural references unless the context clearly dictates otherwise. Where the term “comprising” is used, the present disclosure also contemplates other embodiments “comprising”, “consisting of”, or “consisting essentially of” elements presented herein, whether explicitly set forth or not.

[0016] Any numerical range recited herein includes all values from the lower value to the upper value. For example, if a concentration range is stated as 1% to 50%, it is intended that values such as 2% to 40%, 10% to 30%, or 1% to 3%, etc., are expressly enumerated in this specification. These are only examples of what is specifically intended, and all possible combinations of numerical values between and including the lowest value and the highest value enumerated are to be considered to be expressly stated in this application.

[0017] The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (for example, it includes at least the degree of error associated with the measurement of the particular quantity). The modifier “about” should also be considered as disclosing the range defined by the absolute values of the two endpoints. For example, the expression “from about 2 to about 4” also discloses the range “from 2 to 4.” The term “about” may refer to plus or minus 10% of the indicated number. For example, “about 10%” may indicate a range of 9% to 11%, and “about 1” may mean from 0.9-1.1. Other meanings of “about” may be apparent from the context, such as rounding off, so, for example “about 1” may also mean from 0.5 to 1.4.

[0018] In general, the amount of a component in a composition as disclosed herein is expressed “by weight” which refers to the percentage of the component's weight in the total weight of the composition. Unless indicated otherwise, all concentrations are expressed as weight percentage concentrations.

[0019] The composition described herein comprises at least one copper corrosion inhibiting compound, at least one polymer dispersant, and at least one chelating agent. The at least one chelating agent is desirably present in the composition in an amount of from 0.1% to 10% by weight of the composition. Applicant has found that the inclusion of the chelating agent achieves a synergistic improvement in corrosion inhibition and removal when applied to a copper material.

[0020] The at least one copper corrosion inhibiting compound can be any suitable compound capable of inhibiting corrosion on the surface of the copper material. Suitable examples for use in the composition include azoles such as tolyltriazole (TTA), benzotriazole (BZT), methylbenzotriazole (MBT), halogen stable azole, and mercaptobenzothiazole, including salts thereof. Heterocyclic non-triazole compounds as described in App. No. 63 / 541,425, incorporated herein by reference in its entirety, may also be used as a copper corrosion inhibiting compound. The copper corrosion inhibiting compound can be used alone or in combination of two or more.

[0021] A preferred copper corrosion inhibiting compound for use herein includes sodium tolyltriazole, benzotriazole, mercaptobenzothiazole, any form of a halogenated azole, and combinations thereof.

[0022] The copper corrosion inhibiting compound may be included in the composition in an amount of from about 0.1% to about 50% by weight of the composition, preferably from about 0.1% to about 30%, or from about 0.1% to about 10%, by weight of the composition.

[0023] The at least one chelating agent may include any common chelating agents, for example including an aminopolycarboxylic acid, a hydroxcarboxylic acid such as citric acid and glycolic acid, and polyhydroxycarboxylic acids / sugar acids such as glucaric acid, glucoheptonate, and gluconic acid), and mixtures thereof. Preferred chelating agents are aminopolycarboxylic acids including, for example, ethylenediaminetetraacetic acid (EDTA), 1-glutamic acid, N,N-diacetic acid (GLDA), diethylenetriaminepentaacetic acid (DTPA) and methylglycinediacetic acid (MGDA). The chelating agent can be used alone or in combination of two or more.

[0024] The at least one chelating agent may be included in the composition in an amount of from about 0.01 to about 20% by weight of the composition.

[0025] The chelating agents appear to both solubilize and clean the copper surface.

[0026] The composition also contains at least one polymer dispersant.

[0027] The polymer of the polymer dispersant refers to a macromolecular chain comprising repeating units. The polymer can be a homopolymer of the same repeating monomeric units, or can be a copolymer of one or more, such as two, three (e.g., terpolymers), four (e.g., quad polymers) or more different monomeric units in the chain.

[0028] The monomeric units making up the polymer chain are not particularly limited, and may include monomeric units from, for example, vinyl sulfonic acid, or vinyl sulfonates salts, vinyl phosphonic acid, or vinyl phosphonates salts, vinylidene diphosphonic acid, or salts thereof, acrylic acid, methacrylic acid, vinyl acetate, vinyl alcohol, unsaturated mono- or di-carboxylic acids or anhydrides, such as maleic anhydride, maleic acid, fumaric acid, itaconic acid, aconitic acid, mesaconic acid, citraconic acid, crotonic acid isocrotonic acid, angelic acid, tiglic acid, and the like, vinyl chloride, styrene-p-sulfonic acid, or styrene sulfonates salts, acrylamido-2-methylpropanesulfonic acid (AMPS), hydroxyphosphonoacetic acid (HPA), hypophosphorus acids such as H3PO3, giving units of formula —PO(OH)—, acrylamides, propargyl alcohol having formula HC═C—CH2—OH, butyr-1,4-diol, and the like.

[0029] As described in U.S. Pat. No. 7,087,189 (incorporated herein by reference in its entirety), the polymer may include at least one monomer unit from each of dicarboxylic acids, mono-carboxylic acids, nonionic monomers, and sulfonated or sulfated monomers. The dicarboxylic monomer is one or more ethylenically unsaturated monomer containing two carboxylic acid groups, and includes aliphatic, branched or cyclic dicarboxylic acids, the alkali or alkaline earth metal or ammonium salts thereof, and the anhydrides thereof. Examples of dicarboxylic acid monomers include, but are not limited to itaconic acid, maleic acid, and maleic anhydride, citraconic acid, mesaconic acid, glutaconic acid, aconitic acid, fumaric acid, and tricarboxy ethylene, or mixtures thereof. Preferred dicarboxylic acid monomers are maleic acid or maleic anhydride. The mono-carboxylic acid monomer is one or more ethylenically unsaturated monomers having a single carboxylic acid functionality and includes aliphatic, branched or cyclic, mono-carboxylic acids, and the alkali or alkaline earth metal or ammonium salts thereof. Examples of mono-carboxylic acid monomers includes acrylic acid, methacrylic acid, ethacrylic acid, alpha-chloro-acrylic acid, alpha-cyano acrylic acid, alpha-chloro-acrylic acid, alpha-cyano acrylic acid, beta methyl-acrylic acid (crotonic acid), alpha-phenyl acrylic acid, beta-acryloxy propionic acid, sorbic acid, alpha-chloro sorbic acid, angelic acid, cinnamic acid, p-chloro cinnamic acid, beta-styryl acrylic acid (1-carboxy-4-phenyl butadiene-1,3), and mixtures thereof. The non-ionic monomer is an ethylenically unsaturated nonionic monomer including monomers represented by the chemical structure R3-X1-(CR1R2)-(CH)═(CR7)-(CR8R9)-X2-R10, wherein n1 and n2 are independently 0 to 10; R1, R2, R8 and R9 are independently hydrogen, C1-C6 alkyl, or C1-C6 alkyl-substituted aryl; R7 is hydrogen, or C1-C6 alkyl; X1 and X2 are absent or are independently O, C—O, or hydrogen; R3 is absent or is C—OR4, OR4, NR5R6, C1-C18 alkyl or hydrogen, where R4 is C1-C18 alkyl or hydrogen and R5 and R6 are independently hydrogen, C1-C6 alkyl, or an alkyloxyether or alcohol; and R10 is absent or is C—OR11, OR11, NR12R13, C1-C18 alkyl, or hydrogen, where R11 is C1-C18 alkyl or hydrogen, R12 and R13 are independently hydrogen, C1 to C6 alkyl, or an alkyloxyether or alcohol, such as C1-C6 alkyl esters of (meth)acrylic acid and the alkali or alkaline earth metal or ammonium salts thereof, acrylamide and the C1-C6 alkyl-substituted acrylamides, the N-alkyl-substituted acrylamides and the N-alkanol-substituted acrylamides. The sulfonated or sulfated monomer is one or more ethylenically unsaturated monomers containing a sulfonate functionality, such as (meth)acrylamido methyl propane sulfonic acid, styrene sulfonic acid, acrylamido alkyl or aryl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, and salts thereof.

[0030] The polymer dispersant may be included in the composition in any suitable amount, for example in an amount of from about 0.1% to about 50% by weight of the composition, including from about 1% to about 30% by weight or about 5% to about 20% by weight of the composition.

[0031] In total, the composition may include the chelating agent and the polymer dispersant in amounts such that a concentration of the chelating agent and polymer dispersant is in the range of, for example, 1-1000 ppm, such as 1-500 ppm, in the composition or treatment fluid, during storage or service.

[0032] In addition to the foregoing, the composition may also include additional optional additives. One such additive is a buffer such as triethanolamine or borax. Fluorescent tracers such as PTSA (1,3,6,8-pyrenetetrasulfonic acid) or NDSA (naphthalene disulfonate) may also be present.

[0033] The composition can also include water, such as distilled water and / or deionized water or RO water or city / tap water. The composition may be a dry product, supplied and / or fed as such, i.e., contain 0% by weight of water, or may include from about 10% to about 90% by weight of water. If water is included, the components of the composition should all be sufficiently water soluble to not settle out of the composition. Note that the amounts of water indicated for the composition are prior to use of the composition in subsequent copper corrosion inhibition and / or removal, where the composition may be included in a solution with water for such treatment.

[0034] The composition may be formed in any suitable manner, for example by mixing together the various components of the composition.

[0035] The composition finds utility in inhibiting oxidation and corrosion of a copper surface and / or in removing, for example through cleaning, any and corrosion byproducts that do occur on a copper surface.

[0036] As the copper of the copper surface, any copper, i.e., copper containing material, may be used. The copper may be pure copper, a copper alloy, or a metal including a measurable amount of copper.

[0037] In preferred embodiments herein, the copper is in the form of a mold for a continuous casting machine. In such molds, cooling water is provided to the side of the copper mold opposite the side in contact with the molten metal, such as molten steel, in order to extract heat from the molten metal and mold, and thereby assist in the cooling process of the molten metal as it passes through the mold.

[0038] As noted earlier, the use of cooling water, while effective for heat extraction, can also cause corrosion, oxidation and byproduct fouling on the copper surface contacted by the cooling water. Such corrosion, oxidation and related byproduct fouling can be inhibited, and if it occurs can be cleaned and removed, by application of the compositions herein to the surface of the copper.

[0039] The application of the composition to the copper surface can be done at any suitable stage. For example, the composition can be applied to the copper surface upon formation of the mold from the copper and before use in a continuous molding machine. The composition can also be applied to the copper surface following a refurbishing cleaning of the mold removed from the machine and prior to re-installation. The composition may also be used during offline storage of the mold, for example during maintenance, a cleaning or refurbishing, of the mold prior to re-installation. As an example, the mold may be contained in a steel container, and the container filled with a treatment fluid that includes the composition. The treatment fluid can protect both the copper mold and the steel container, and in this regard the treatment fluid or composition can also include a steel corrosion inhibitor such as a nitrite compound.

[0040] In either case, the copper surface may be polished prior to application of the composition thereto. The composition can be applied as is, or the composition can be added to water, preferably purified water, to form a solution that is applied to the aforementioned copper surfaces. In these treatments, the composition or solution may be applied to the surface by any suitable method, such as by spraying, or the copper surface can be immersed in the composition or solution to soak.

[0041] For a solution, the composition can be added to a treatment solution in an amount of about 100 ppm to about 50000 ppm to process water.

[0042] In addition, when the mold is in use in a continuous molding machine, the surface of the copper mold exposed to the cooling water may be treated by including the composition in the cooling water, at a concentration the same as the treatment solution discussed above. The cooling water, which is preferably in a closed loop recirculating system, may be continuously monitored for the amount of the composition remaining therein, and continuously dosed with additional amounts of the composition to retain a substantially steady state amount of the composition in the cooling water fed to the mold.

[0043] In a method of forming a cast metal in a continuous casting process, molten metal is provided into a continuous casting machine including a copper mold, and cooling the molten metal as the molten metal passes through the copper mold. The cooling preferably includes adding the composition of the present application into cooling water fed to a surface of the copper mold away from the molten metal, the cooling water contacting the surface of the copper mold and thereby inhibiting oxidation and corrosion of the surface and / or removing oxidation and corrosion byproducts from the surface. In the process, predetermined heat transfer rates are able to be maintained in order to solidify the molten metal exiting the copper mold to form a cast metal free of heat transfer related defects.

[0044] The addition of a chelating agent may result in a synergistic boost in the copper corrosion inhibition performance of the composition, particularly compared to compositions simply containing additional copper corrosion inhibiting compounds or containing only polymer dispersants.

Examples

Embodiment Construction

[0014]Although specific embodiments are described herein, the scope of the invention and claims is not limited to only those specific embodiments. The scope of the invention is defined by the following claims and any equivalents therein. As will be appreciated by one skilled in the art, aspects of the present disclosure may be embodied as an apparatus, system or method.

[0015]The terms “comprise(s),”“comprising,”“include(s),”“including,”“having,”“has,”“contain(s),”“containing,” and variants thereof, as used herein, are open-ended transitional phrases, terms, or words that are meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The singular forms “a”, “and”, and “the” include plural references unless the context clearly dictates otherwise. Where the term “comprising” is used, the present disclosure also contemplates other embodiments “comprising”, “consisting of”, or “consisting essentially of” elements presented herein, whether explicit...

Claims

1. A composition comprisingat least one copper corrosion inhibiting compound,at least one polymer dispersant, andat least one chelating agent,wherein the at least one chelating agent is included in the composition in an amount of from about 0.01% to about 20% by weight of the composition.

2. The composition according to claim 1, wherein the at least one copper corrosion inhibiting compound is selected from the group consisting of azole compounds, heterocyclic non-triazole compounds, and mixtures thereof, and comprises from about 0.1% to about 50% by weight of the composition.

3. The composition according to claim 1, wherein the at least one chelating agent is an aminopolycarboxylic acid, a hydroxcarboxylic acid, polyhydroxycarboxylic acids / sugar acids, and mixtures thereof.

4. The composition according to claim 1, wherein the at least one polymer dispersant comprises from about 0.1% to about 50% by weight of the composition.

5. The composition according to claim 1, wherein the at least one polymer dispersant comprises from about 1% to about 30% by weight of the composition.

6. The composition according to claim 1, wherein the at least one polymer dispersant comprises from about 5% to about 20% by weight of the composition.

7. The composition according to claim 1, wherein a concentration of a total of the chelating agent and the polymer dispersant in the composition is from 1-1000 ppm.

8. The composition according to claim 1, wherein the composition further includes water.

9. A method of inhibiting oxidation and corrosion of a copper surface and / or removing oxidation and corrosion byproduct fouling on a copper surface, comprising applying the composition of claim 1 to the copper surface.

10. The method according to claim 9, wherein prior to the applying, the copper surface is polished and / or cleaned.

11. The method according to claim 9, wherein the applying comprises adding the composition to water to form a solution, and submersing the copper surface in the solution.

12. The method according to claim 9, wherein the applying comprises adding the composition into cooling water, and feeding the cooling water to a surface of a copper mold.

13. The method according to claim 9, wherein the composition is applied as a dry product.

14. A method of forming a cast metal in a continuous casting process, comprisingproviding molten metal into a continuous casting machine including a copper mold,cooling the molten metal as the molten metal passes through the copper mold, the cooling comprising adding the composition of claim 1 into cooling water fed to a surface of the copper mold away from the molten metal, the cooling water contacting the surface of the copper mold and thereby inhibiting oxidation and corrosion of the surface and / or removing oxidation and corrosion byproducts from the surface, andmaintaining predetermined heat transfer rates to solidify molten metal exiting the copper mold to form a cast metal free of heat transfer related defects.