Method for chemically reducing metals in waste compositions

A method for the indirect chemical reduction of at least two oxygen-containing metal compounds of a metal-containing waste composition, comprising the steps of:

• a) directing the metal-containing waste composition into a molten bath, including a first reducing agent which, under the operating conditions of the molten bath, chemically reduces a first oxygen-containing metal compound of the metal-containing composition to form a metal oxide;
• and
• b) directing a second reducing agent into the molten bath, the second reducing agent, under the operating conditions of the molten bath, chemically reducing the metal oxide, and being directed into the molten bath at a rate, relative to the rate at which the metal of the oxygen-containing metal compound is directed into the subsequently formed metal oxide to dissolve in the molten bath, thereby indirectly chemically reducing the first oxygen-containing metal compound of the metal-containing composition;
• and thereafter
• c) directing a sacrificial metal into the molten bath after the second reducing agent has reduced at least a significant portion of the second metal oxide, the sacrificial metal being substantially soluble in the metal bath and having a lower free energy of oxidation than the second reducing agent, whereby the sacrificial reacts with a second oxygen-containing metal compound of the waste composition, the second oxygen-containing metal compound being substantially inert to the first and second reducing agents at the temperature of the molten bath, thereby chemically reducing the second oxygen-containing metal compound of the waste composition.

A method for chemically remediating a oxygen-containing metal contaminant of a metal-containing composition, comprising the steps of:

• a) directing the metal-containing composition into a molten bath which includes a first reducing agent that, under the operating conditions of the molten bath, chemically reduces the oxygen-containing metal contaminant of the metal-containing composition to form a metal oxide and a reduced metal component of the metal-containing metal composition;
• b) directing a second reducing agent into the molten bath which, under the operating conditions of the molten bath, reduces the metal oxide, and at a rate, relative to the rate at which the metal-containing composition is directed into the molten bath, which is sufficient to cause essentially all subsequently formed metal oxide to dissolve in the molten bath;
• and thereafter
• c) reclaiming the reduced metal component of the metal-containing composition from the molten bath.