Patent ID: 7931753

Claim:
A method for removing a deposit containing magnetite and copper from a container, which comprises the steps of: in a first step, treating a deposit containing magnetite and copper in the container with an alkaline cleaning solution containing a reducing agent, an alkalizing agent, and a complexing agent forming a soluble complex with iron(II) ions originating from the magnetite, wherein the first step dissolves the magnetite in the alkaline cleaning solution; in a second step, metering a further complexing agent which forms a more stable complex with iron(III) ions than the complexing agent used in the first step, and an oxidizing agent, into the alkaline cleaning solution of the first step which is present in the container, wherein the further complexing agent has a different chemical composition than the complexing agent used in the first step, the second step dissolves the copper in the alkaline cleaning solution; and removing the magnetite and the copper from the container by discharging the alkaline cleaning solution from the container.