Composition and process for the removal of copper during acid cleaning of ferrous alloys

Claim 2

AN ADDITIVE FOR USE IN COMPOSITIONS FOR THE REMOVAL OF COPPER ENCRUSTATIONS ENCOUNTERED DURING ACID CLEANING OPERATIONS OF FERROUS ALLOY CONTAINING ESSENTIALLY OF THE REACTION PRODUCT OF A. AN ALIPHATIC OR CYCLOALIPHATIC ALDEHYDE HAVING FIVE CARBON ATOMS OR LESS: B. AN AMINE HVING AN HYDROXYETHYL OR SUBSTITUTED HYDROXYETHYL GROUP ATTACHED TO AN AMINO NITROGEN ATOMS: AND C. THIOUREA, THE RATIO OF CARBON ATOMS IN THE ALIPHATIC OR CYCLOALIPHATIC SUBSTITUENTS TO THE NUMBER OF POLAR GROUPS THEREIN BEING NO GREATER THAN ABOUT 5-TO-1, THE MOLAR EQUILAVENT OF ALDEHYDE BEING BETWEEN ABOUT 1.0 AND ABOUT 2.5 PER MOLE OF THIOUREA, THE MOLAR EQUILAVENT OF HYDROXY PRESENT IN THE AMINE BEING FROM ABOUT 1.0 TO ABOUT 2.5 TIME THE NUMBER OF MOLES OF THIOUREA, AND THE MOLAR EQUILAVENT OF HYDROXY BEING EQUAL TO THE MOLAR EQUILAVENT OF ALDHYDE.

Claim 3

The additive of claim 1 wherein the ratio of carbon atoms in the aliphatic or cycloaliphatic substituents to the number of polar groups therein is below about 3-to-1.

Claim 4

The additive of claim 1 wherein the aldehyde is selected from the class consisting of formaldehyde, trioxane, paraformaldehyde, acetaldehyde, propionaldehyde, furfural, glyoxal, gluteraldehyde, acrolein and caproaldehyde.

Claim 5

The additive of claim 1 wherein the aldehyde is selected from the class consisting of paraformaldehyde, trioxane, paraldehyde and metaldehyde.

Claim 6

The additive of claim 1 wherein the amine contains less than about 7 carbon atoms per amino nitrogen atom.

Claim 7

The additive of claim 1 wherein the amine contains three carbon atoms per amino nitrogen atom.

Claim 8

The additive of claim 1 wherein the amine contains about two carbon atoms per amino nitrogen atom.

Claim 9

The additive of claim 1 wherein the amine is selected from the class consisting of 2-hydroxy-propylamine, monoethanolamine, diethyl monoethanolamine, diethanolamine, methyl diethanolamine, triethanolamine, hydryoxyethylethylene diamine and di-2-hydroxypropylamine.

Claim 10

A composition for the removal of copper compounds during acid cleaning operations of ferrous alloy surfaces consisting essentially of an aqueous solution of an acid and the additive of claim 1, the ratio of acid in said composition to the amine in the additive being at least as high as about 1-to-5 by volume.

Claim 11

The composition of claim 9, wherein the acid is an organic acid.

Claim 12

The composition of claim 9 wherein the acid is an inorganic acid.

Claim 13

The composition of claim 9 wherein the acid is selected from the class consisting of acetic, hydrochloric, sulfuric and phosphoric.

Claim 14

The composition of claim 9 wherein the acid is acetic.

Claim 15

A process for the removal of copper encrustations on ferrous alloy surfaces comprising the steps of: a. Contacting the ferrous surface with an aqueous solution of (1) the additive of claim 1 in an amount sufficient to provide from about 1.8 to about 5.0 pounds of sulphur for each pound of copper ion, and (2) an acid selected from the class consisting of acetic, hydrochloric, sulfuric and phosphoric, the amount of acid in said solution being a ratio to the amine in the additive of at least as high as about 1-to-5 by volume; and b. Maintaining contact with the said ferrous surface by the said aqueous solution for a time sufficient to substantially solubilize the said copper encrustation.

Claim 16

The process for the removal of copper encrustations on ferrous alloy surfaces comprising the steps of: a. Contacting the ferrous surface with an squeous solution of an additive consisting essentially of the reaction product of (1) an aldehyde having five carbon atoms or less selected from the class consisting of aliphatic and cycloaliphatic aldehydes, (2) an amine having a hydroxyethyl or substituted hydroxyethyl group attached to an amino nitrogen atom, and (3) thiourea, said additive being present in an amount sufficient to provide from about 1.8 to about 5.0 pounds of sulphur for each pound of copper present, and an aqueous acidic solution comprising an acid selected from the class consisting of acetic, hydrochloric, sulphuric, and phosphoric acids; and b. Maintianing contact with said ferrous surface by the said aqueous acidic solution having present therein the said additive for a time sufficient to solubilize substantially all of said encrustation.

Claim 17

The process for the removal of copper encrustations on ferrous alloy surfaces comprising the steps of: a. Contacting the ferrous surface with an squeous solution of an additive consisting essentially of the reaction product of (1) an aldehyde having five carbon atoms or less selected from the class consisting of aliphatic and cycloaliphatic aldehydes, (2) an amine having a hydroxyethyl or substituted hydroxyethyl group attached to an amino nitrogen atom, and (3) thiourea, said additive being present in an amount sufficient to provide from about 1.8 to about 5.0 pounds of sulphur for each pound of copper present, and an aqueous acidic solution comprising an acid selected from the class consisting of acetic, hydrochloric, sulphuric, and phosphoric acids; and b. Maintianing contact with said ferrous surface by the said aqueous acidic solution having present therein the said additive for a time sufficient to solubilize substantially all of said encrustation.

Claim 18

The process of claim 15 wherein the aldehyde is selected from the class consisting of formaldehyde, trioxane, paraformaldehyde, acetaldehyde, propionaldehyde, furfural, glyoxal, fluteraldehyde, acrolein and caproaldehyde.

Claim 19

The process of claim 15 wherein the aliphatic or cycloaliphatic reactant contains less than four carbon atoms per aldehyde group.

Claim 20

The process of claim 15 wherein the aldehyde is selected from the class consisting of paraformaldehyde, trioxane, paraldehyde and metaldehyde.

Claim 21

The process of claim 15 wherein the amine contains less than about seven carbon atoms per amino nitrogen atom.

Claim 22

The process of claim 15 wherein the amine contains 3 carbon atoms per amino nitrogen atom.

Claim 23

The process of claim 15 wherein the amine contains about two carbon atoms per amino nitrogen atom.

Claim 24

The process of claim 15 wherein the amine is selected from the class consisting of 2-hydroxy-propylamine, monoethanolamine, diethyl monoethanolamine, diethanolamine, methyl diethanolamine, triethanolamine, hydroxyethylethylene diamine and di-2-hydroxypropylamine.