Removal of copper containing incrustations from ferrous surfaces
AssigneeThe Dow Chemical Company
InventorsLester W. Harriman, Paul E. Muehlberg, Fred N. Teumac
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Abstract
The invention concerns a method of removing copper from a ferrous metal surface without excessive corrosion of the ferrous metal surface. In the method, the copper is dissolved with an aqueous alkaline solution containing a ferric chelate of an alkylene polyamine polyacetic acid chelating agent.
Claims25
A process for removing copper from a ferrous metal surface containing copper thereon by contacting said surface with an aqueous alkaline solution wherein the solution employed contains as an essential constituent at least one member of the group consisting of ferric chelates of [polycarboxylic] alkylene polyamine polyacetic acid chelating agents and mixtures of ferric and ferrous chelates of [polycarboxylic] alkylene polyamine polyacetic acid chelating agents in amount sufficient and for a time sufficient at a reaction temperature above about 68.degree. F. and up to about 300.degree. F., to dissolve said copper , wherein said solution may also contain a salt of the group consisting of ammonium, amine, and hydroxyalkylamine salts of alkylene polyamine polyacetic acid chelating agents . [
A process as claimed in claim [2] 1 wherein the total iron chelate originally present ranges between about 60 and about 100 weight percent of total salt form and iron chelate and the solution originally contains a total of between ca. 0.5 weight percent and up to a saturated solution of salt form and iron chelated chelating agent.
[6. A process as claimed in claim 3 wherein the iron chelate and
- chelating agent salt are those of ethylenediaminetetraacetic acid.] 7. A process as claimed in claim 3 wherein the reacted ferrous surface is
- rinsed with rinse water containing a water-soluble oxidant. 8. A process as claimed in claim 3 wherein the reacted ferrous surface is rinsed with
- rinse water while air is bubbled therethrough. 9. A process for removing copper from a ferrous metal surface containing copper thereon by contacting said surface with an aqueous alkaline solution wherein the solution contains as an essential constituent ammoniated ethylenediaminetetraacetic acid adjusted to a pH of about 9 with free ammonia and iron chelate thereof wherein the iron chelate originally present ranges between about 60 and ca. 100 weight percent of total salt form ethylenediaminetetraacetic acid and iron chelate thereof and the solution originally contains between about 0.5 weight percent and up to a saturated solution of total salt form and iron chelate of ethylenediaminetetraacetic acid while air is being bubbled therethrough at a reaction temperature above about 68.degree. F. and up to about 300.degree. F. in amount sufficient and for a time sufficient to dissolve said copper, removing said solution from said ferrous metal surface, contacting said surface with rinse water while bubbling air therethrough and removing said rinse water.
A process for removing copper from a ferrous metal surface containing copper thereon by contacting said surface with an aqueous alkaline solution wherein the solution employed contains as an essential constituent at least one member of the group consisting of ferric chelates of ethylenediaminetetraacetic acid and mixtures of ferric and ferrous chelates of ethylenediaminetetraacetic acid in amount sufficient and for a time sufficient at a reaction temperature above about 68.degree. F. and up to about 300.degree. F. to dissolve said copper, wherein said solution may also contain a salt of the group consisting of ammonium, amine and hydroxyalkylamine salts of ethylenediaminetetraacetic acid and wherein the total iron chelate originally present ranges between about 60 and about 100 weight percent of total salt form and iron chelate and the solution originally contains a total of between ca. 0.5 weight percent and up to a saturated solution of salt form and iron chelated chelating agent.
Dependencies are inferred from the claim text.