Cleaning and liquid contact with solids – Processes – For metallic – siliceous – or calcareous basework – including...
Patent
1995-12-08
1997-10-21
El-Arini, Zeinab
Cleaning and liquid contact with solids
Processes
For metallic, siliceous, or calcareous basework, including...
134 10, 134 2213, 134 2214, 134 2216, 134 2217, 134 2219, 134 41, B08B 308, B08B 900, C23G 102, C23G 108
Patent
active
056791704
ABSTRACT:
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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El-Arini Zeinab
Hydrochem Industrial Services, Inc.
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