| 摘要 |
A method and solution for removing iron oxide-containing scale from the interior surfaces of steel vessels. During normal cleaning procedures for internal scale-encrusted steel surfaces of a utility boiler, a reducing atmosphere is maintained, and an aqueous solution containing an about 4:1 to about 9:1 weight ratio of formic acid and citric acid, is placed in dissolving relation to the scale. The high F/C ratios hold more iron in solution than low F/C ratios, especially if the iron is kept in the 2+oxidation state. The ability of the solution to hold dissolved iron is only slightly dependent on pH, so long as pH is maintained below 7.0. An oxidation stage is not required to remove dissolved iron to below 1 ppm from the solution, during waste treatment procedures using lime and NaOH.
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