US Patent 7144512 Method of reclaiming brine solutions using an organic chelant

A method of reclaiming a well completion brine solution by using an organic chelant that is capable of discriminating between (i) iron and non-zinc heavy metals; and (ii) calcium and zinc. The chelant contains a functional group selected from the group —CO2H or —PO(OH)R20 or a salt or ester thereof, —C(O)—, —OE, —SE, —N═C(R2)R3, EO—N═C(R2)R3, —N(R2)R3, and —N(C(O)R1)R2 group optionally substituted with a —COOH or —PO(OH)R20 or a salt or ester thereof, —SE or —OE group, wherein R2 and R3 are independently selected from E or forms, with nitrogen, phosphorous, oxygen or sulfur, a heterocyclic ring; E is R1 or —H; R1 is a C1–C30 alkyl or aralkyl group or a derivative thereof and R20 is —OH or R1.