Corrosion inhibitor for nitrogen fertilizer solutions
AssigneeNalco Chemical Company
InventorsRaymond T. Cunningham, Kristen T. Moore
Life of this patent
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Abstract
A trace amount of a molybdate is disclosed for inhibiting corrosion by concentrated urea-ammonium nitrate fertilizer solutions (UAN) in contact with ferrous metal piping and equipment surfaces. From 10 to 200 ppm of sodium molybdate are blended in a UAN solution containing 20-50 weight percent water for effectively inhibiting corrosion. The corrosion-inhibited UAN solution is non-sludging, non-foaming and essentially free of precipitates.
Claims12
In a method for inhibiting corrosion of ferrous metal surfaces by nitrogen fertilizer solutions in contact therewith, including the steps of blending a corrosion inhibitor with a fertilizer solution consisting essentially of urea, ammonium nitrate and a minor amount of water, and contacting the metal surfaces with the resulting blend, the improvement consisting of:
- using an effective, soluble amount less than 200 ppm, by weight of the fertilizer solution, of an alkali metal molybdate as the corrosion inhibitor in the blending step.
A method for processing a liquid nitrogen fertilizer in ferrous metal equipment without excessive corrosion, consisting of the steps of:
- (a) blending (1) a solution of urea, (2) a solution of ammonium nitrate, (3) optional water and (4) an aqueous solution of an alkali metal molybdate;
- (b) recovering the blend from step (a), wherein the blend is effectively inhibited against ferrous metal corrosion and comprises a precipitate-free, non-sludging, non-foaming solution containing more than 10 and less than 100 ppm of the alkali metal molybdate and from about 20 to about 50 percent water;
- (c) passing the corrosion-inhibited blend in contact with ferrous metal surfaces.
A corrosion-inhibited liquid fertilizer, consisting of a non-sludging, non-foaming, precipitate-free solution of urea and ammonium nitrate, of more than 20 and less than 50 percent water by weight and from 10 to 100 ppm sodium or potassium molybdate, having a pH of from 7.5 to 8.0 at atmospheric pressure and essentially non-corrosive to ferrous metal surfaces.
Dependencies are inferred from the claim text.