Claims
- 1. A method of dissolving solid iron oxide comprising providing an electrolyte of water and not less than about 14% by volume phosphoric acid or not less than 12% by weight citric acid or a combination thereof, the balance water in contact with an anode and a cathode of the solid iron oxide to be dissolved, and applying a direct negative current of not less than about 12 milliamps between the solid iron oxide cathode and an anode for a time sufficient to dissolve a portion of the solid iron oxide.
- 2. The method of claim 1, wherein the current between the anode and cathode is in the range of from about 12 milliamps to about 500 milliamps and the cathode is partially submerged in the electrolyte.
- 3. The method of claim 2, wherein the current between the anode and cathode is not less than about 25 milliamps.
- 4. The method of claim 2, wherein the voltage is in the range of from about 20 volts to about 200 volts.
- 5. The method of claim 1, wherein the cathode is fully submerged in the electrolyte.
- 6. The method of claim 1, wherein the anode is copper or silver or an alloy thereof.
- 7. The method of claim 1, wherein the iron oxide includes FeO.
- 8. The method of claim 1, wherein the iron oxide includes Fe.sub.2 O.sub.3.
- 9. The method of claim 1, wherein the iron oxide includes Fe.sub.3 O.sub.4.
- 10. The method of claim 1, wherein the iron oxide includes FeO and Fe.sub.2 O.sub.3.
- 11. The method of claim 1, wherein the phosphoric acid is present in an amount less than about 55% by volume.
- 12. The method of claim 1, wherein the citric acid is present in an amount of less than about 45% by weight.
- 13. In a coil for a heat exchanger clogged by deposits of iron oxide lodged inside the coil, the method of dissolving the iron oxide comprising, providing an electrolyte solution of water with one or more of phosphoric acid or citric acid present in the water in contact with the coil and the iron oxide inside the coil, the phosphoric acid being present in the amount of from about 14% by volume to about 55% by volume, said citric acid being present in the amount of from about 12% by weight to about 45% by weight, establishing a direct negative current of not less than about 12 milliamps between an anode and the deposit of iron oxide clogging the inside of the coil for a time sufficient to dissolve enough of the iron oxide to enable the coil to be flushed.
- 14. The method of claim 13, wherein the time necessary to unclog the coil is about 2 to about 4 hours.
- 15. The met hod of claim 13, wherein the electrolyte is maintained at about ambient temperature.
- 16. The method of claim 13, wherein the temperature of the electrolyte is elevated above ambient temperatures and below the boiling point of the electrolyte.
- 17. The method of claim 13, wherein 20 to 200 volts is applied across the anode and cathode.
- 18. The method of claim 17, wherein the current is in the range of from about 12 milliamps to about 500 milliamps.
- 19. The method of claim 13, wherein the current is not less than about 25 milliamps.
- 20. The method of claim 13, wherein the cathode of iron oxide is submerged in the electrolyte and the current does not exceed 133 amps.
Parent Case Info
This application is a continuation-in-part of U.S. patent application Ser. No. 402,869, filed Sept. 5, 1989.
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1195704 |
Marino |
Aug 1916 |
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4264418 |
Wood et al. |
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Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
402869 |
Sep 1989 |
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