Method for indirect chemical reduction of metals in waste
DCFirst Claim
1. A method for indirect chemical reduction of a component of a waste, comprising the steps of:
- a) directing the waste, containing the component, into a molten metal bath, including a metal-containing first reducing agent which, under the operating conditions of the molten metal bath, chemically reduces said component of the waste to form a dissolved metal-containing intermediate;
b) directing a metal-ligand exchange reagent into the molten metal bath, said metal-ligand exchange reagent causing a metal-ligand exchange reaction with the metal-containing intermediate to form a metal-ligand exchange product which includes the metal of the intermediate; and
c) exposing the metal-ligand exchange product to a second reducing agent in the molten metal bath which, under the operating conditions of the bath, chemically reduces the metal of the metal-ligand exchange product at a rate, relative to the rate at which the component of the waste is directed into the molten metal bath, which is sufficient to cause essentially all metal of the metal-containing intermediate formed to be reduced in the molten metal bath, thereby indirectly reducing the component of the waste.
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Abstract
An environmentally sound process is described for the remediation of waste materials that allows the separation, recovery and decontamination of metals. The method includes chemically reducing essentially all of a reducible toxic and potentially hazardous metal-containing component of a waste composition. The waste is directed into a molten metal bath, including a first reducing agent which, under the operating conditions of the molten metal bath, chemically reduces a metal of the metal-containing component to form a dissolved intermediate. A reagent is directed into the molten metal bath for metal-ligand exchange with the dissolved intermediate to form a metal-ligand exchange product that includes the metal of the dissolved intermediate. A second reducing agent is directed into the molten metal bath. The second reducing agent, under the operations of the molten metal bath, chemically reduces the metal of the metal-ligand exchange product. The rate at which the second reducing agent is directed into the molten metal bath, relative to the rate at which the component of the waste is directed into the molten metal bath, is sufficient to cause essentially all metal of the metal-containing intermediate formed to be reduced in the molten metal bath, thereby indirectly chemically reducing the component of the waste. This indirect reduction technology can remediate a variety of materials, including ash metal-contaminated municipal waste, vitreous slag-like materials and spent metal catalysts, while allowing the recovery of remediable metals.
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Citations
37 Claims
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1. A method for indirect chemical reduction of a component of a waste, comprising the steps of:
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a) directing the waste, containing the component, into a molten metal bath, including a metal-containing first reducing agent which, under the operating conditions of the molten metal bath, chemically reduces said component of the waste to form a dissolved metal-containing intermediate; b) directing a metal-ligand exchange reagent into the molten metal bath, said metal-ligand exchange reagent causing a metal-ligand exchange reaction with the metal-containing intermediate to form a metal-ligand exchange product which includes the metal of the intermediate; and c) exposing the metal-ligand exchange product to a second reducing agent in the molten metal bath which, under the operating conditions of the bath, chemically reduces the metal of the metal-ligand exchange product at a rate, relative to the rate at which the component of the waste is directed into the molten metal bath, which is sufficient to cause essentially all metal of the metal-containing intermediate formed to be reduced in the molten metal bath, thereby indirectly reducing the component of the waste. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. A method for chemically remediating a metal-containing component of a waste, comprising the steps of:
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a) directing the waste, containing the component, into a molten metal bath, including a metal-containing first reducing agent which, under the operating conditions of the molten bath, chemically reduces said component of the waste to form a dissolved metal-containing intermediate; b) directing a metal-ligand exchange reagent into the molten metal bath, said metal-ligand exchange reagent causing a metal-ligand exchange reaction with the metal-containing intermediate to form a metal-ligand exchange product which includes the metal of the intermediate; c) exposing the metal-ligand exchange product to a second reducing agent in the molten metal bath which, under the operating conditions of the bath, chemically reduces the metal of the metal-ligand exchange product at a rate, relative to the rate at which the component of the waste is directed into the molten metal bath, which is sufficient to cause essentially all metal of the metal-containing intermediate formed to be reduced in the molten metal bath; and
thereafterd) reclaiming the reduced metal component of the waste from the molten metal bath.
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Specification