Claims
- 1. A composition for dissolving an alkaline earth metal sulfate scale consisting essentially of:
- a) an aqueous solution having a pH of from about 10 to about 14 which is provided by the presence of potassium hydroxide;
- b) a chelating agent comprising a polyaminopolycarboxylic acid or a salt of such an acid in an amount from about 0.1M to about 1.0M; and
- c) a synergistic scale-dissolving quantity of oxalate anion in an amount from 0.1M to 1.0M.
- 2. The composition as recited in claim 1 where the chelating agent is EDTA or DTPA.
- 3. The composition as recited in claim 1 where the chelating agent is present in an amount of from 0.3M to 0.6M.
- 4. The composition as recited in claim 1 where the oxalate anion is present in a concentration of from 0.1M to 0.6M.
- 5. The composition as recited in claim 4 where the oxalate anion is present in a concentration of 0.3M to 0.6M.
- 6. The composition as recited in claim 1 where the pH is adjusted to about 12 with potassium hydroxide, the chelant comprises DTPA and the synergist comprises oxalate anions.
- 7. The composition as recited in claim 1 where the pH of the solution is from 10 to 13.
- 8. The composition as recited in claim 1 where the pH of the solution is about 12.
Parent Case Info
This is a division of copending application Ser. No. 369,897 filed on Jun. 22, 1989, now U.S. Pat. No. 4,980,077 which is a continuation-in-part of Ser. No. 332,147 now U.S. Pat. No. 5,093,020.
US Referenced Citations (12)
Foreign Referenced Citations (2)
Number |
Date |
Country |
107297 |
Jul 1982 |
JPX |
174990 |
Jan 1985 |
JPX |
Non-Patent Literature Citations (1)
Entry |
Hawley's Condensed Chemical Dictionary, 11th edition, Van Nostrand Rienhold, N.Y. 1987, pp. 391, 486. |
Divisions (1)
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Number |
Date |
Country |
Parent |
369897 |
Jun 1989 |
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Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
332147 |
Apr 1989 |
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