Claims
- 1. A method for removing barium sulfate scale comprising contacting the scale with an aqueous solution having a pH of about 8 to about 14 and consisting essentially of a chelating agent comprising a polyaminopolycarboxylic acid or salt of such an acid in a concentration of 0.1 to 1.0 M, and anions of a monocarboxylic acid selected form mercaptoacetic acid, hydroxyacetic acid, aminoacetic acid, or salicyclic acid in a concentration of 0.1 to 1.0 M and which is soluble in the solution under the selected pH conditions, to dissolve the scale.
- 2. The method as recited in claim 1 wherein the chelating agent comprises DTPA.
- 3. The method as recited in claim 1 where the pH of the solution is from 11 to 13.
- 4. The method as recited in claim 1 wherein the scale is contacted with the solution for a time of up to 4 hours.
- 5. The method as recited in claim 1 where the pH of the solution is provided by the use of a potassium base.
- 6. The method as recited in claim 1 where the potassium base is potassium hydroxide.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation part of prior co-pending application Ser. No. 07/332,147, filed 3 Apr. 1989, of J.M.Paul and R.L.Morris.
This application is also related to prior application No. 07/369,897, filed 22 June 1989, of the same inventors.
US Referenced Citations (14)
Foreign Referenced Citations (2)
Number |
Date |
Country |
61-174990 |
Nov 1985 |
JPX |
63-178199 |
Jan 1987 |
JPX |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
332147 |
Apr 1989 |
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