A method of removing metal scale from surfaces that includes contacting
the surfaces with a first aqueous solution of a chelating agent, allowing
the chelating agent to dissolve the metal scale, acidifying the solution
to form a precipitant of the chelating agent and a precipitant of the
metal from the metal scale, isolating the precipitant of the chelating
agent and the precipitant of the metal from the first solution,
selectively dissolving the precipitated chelating agent in a second
aqueous solution, and removing the precipitated metal from the second
solution is disclosed.