Patent ID: 7470330
Filing Date: 2008-12-30
Classification: C01F,C02F,C09K,C22B,C23F,Y02P

Abstract:
1. A method of removing metal scale from surfaces, comprising: contacting the surfaces with a first aqueous solution comprising: allowing the chelating agent to dissolve the metal scale from the surfaces into the first aqueous solution; acidifying the first aqueous solution to form a precipitant of the chelating agent and a precipitant of the metal from the metal scale in the first aqueous solution, wherein both the precipitant of the chelating agent and the precipitant of the metal are present together in the first aqueous solution; isolating the precipitant of the chelating agent and the precipitant of the metal from the first aqueous solution and introducing the precipitant of the chelating agent and the precipitant of the metal into a second aqueous solution; selectively dissolving the precipitant of the chelating agent in the second aqueous solution; and removing the precipitant of the metal from the second aqueous solution.