A
corrosion inhibitor for use with
Urea Ammonium Nitrate solutions is disclosed, comprising a blend of
molybdate and one or more of the inorganic phosphates (including phosphates, polyphosphates, and pyrophosphates) and
organic phosphates or phosphonates. Inorganic phosphates include, but are not limited to, SHMP (
Sodium Hexametaphosphate) and TKPP (
Tetra-
Potassium Pyrophosphate).
Phosphoric acid may also be utilized to provide
phosphate ions, by itself or in combination with other phosphorous containing compounds as a secondary inhibitor. There are numerous other inorganic phosphates that will also serve as suitable secondary inhibitors.
Organic phosphates or phosphonates include, but are not limited to, HEDP (1-Hydroxyethylidine-1,1-diphosphonic acid; also known as
ethanol diphosphonate, acetodiphosphonic acid, or
etidronic acid),
ATMP (aminotri(methylenephosphonic acid)), PBTC (Phosphonobutane
tricarboxylic acid), DETPMP (Diethylenetriaminepenta(
methylene phosphonic acid)), and HPA (hydroxyphosphono
acetic acid). There are numerous other
organic phosphates and phosphonates that will also serve as suitable secondary inhibitors. The amount of
molybdate can range from 1 ppm to 500 ppm by weight of
fertilizer solution, with the preferred range from 10 ppm to 200 ppm. Amounts of inorganic or organic
phosphate can also range from levels as low as 1 ppm up to 500 ppm, with the preferred range being from 5 ppm to 50 ppm.