Primary amine-containing polymers useful as scale inhibitors

A process for inhibiting scale produced during wet process phosphoric acid production, said process comprising:

• adding a reagent comprising a primary amine-containing polyethyleneimine polymer to at least one stage of a wet process phosphoric acid production process, thereby reducing or preventing scale in the wet process phosphoric acid production process,
• wherein said primary amine-containing polyethyleneimine polymer is characterized by having:
• a number average molecular weight from 300 daltons to 300,000 daltons;
• one or more organic moiety independently chosen from a C4-C22 hydrocarbyl group, wherein said organic moiety reduces the polymer's solubility in an aqueous acidic environment as compared to its native form;
• and
• wherein said primary amine-containing polyethyleneimine polymer is added in an amount from 0.5 g per ton to 5000 g per ton of phosphoric acid.