Method of 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, the 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; and
thereafterb) exposing the metal of the metal-containing intermediate to a second reducing agent in the molten metal bath, the second reducing agent, under the operating conditions of the bath, chemically reducing said metal 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-containing intermediate formed to dissolve in the molten metal bath for subsequent reduction of the metal component of said intermediate, 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 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 dissolved intermediate. 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-containing intermediate formed to dissolve 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.
129 Citations
35 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, the 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; and
thereafterb) exposing the metal of the metal-containing intermediate to a second reducing agent in the molten metal bath, the second reducing agent, under the operating conditions of the bath, chemically reducing said metal 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-containing intermediate formed to dissolve in the molten metal bath for subsequent reduction of the metal component of said intermediate, 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)
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27. A method for the indirect chemical reduction of at least two components of a waste, comprising the steps of:
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a) directing the waste into a molten metal bath, the molten metal bath including a first reducing agent which, under the operating conditions of the molten metal bath, chemically reduces a metal of a first component of the waste to form a dissolved metal-containing intermediate; and b) exposing the metal of the intermediate to a second reducing agent in the molten metal bath, the second reducing agent, under the operating conditions of the molten metal bath, chemically reducing the intermediate at a rate, relative to the rate at which the first component of the waste is directed into the molten metal bath, which is sufficient to cause essentially all intermediate formed to dissolve in the molten metal bath for subsequent reduction of the metal component of the intermediate, thereby indirectly chemically reducing the first component of the waste; and
thereafterc) directing a sacrificial metal into the molten metal bath after the second reducing agent has reduced the intermediate, the sacrificial metal being substantially soluble in the molten metal bath and having a lower free energy of oxidation than the second reducing agent, whereby the sacrificial metal reacts with a metal of a second component of the waste, the second component being substantially inert to the first and second reducing agents at the temperature of the molten metal bath, thereby chemically reducing the metal of the second component of the waste. - View Dependent Claims (28, 29, 30, 31, 32, 33)
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34. A method for indirect chemical reduction of a component of a waste, comprising the steps of:
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a) directing the waste into a molten metal bath, whereby a phase of the component is formed in the presence of a molten metal bath, the two phases being substantially immiscible, the molten metal bath including a-first reducing agent which, at the operating conditions of the molten metal bath, chemically reduces a significant portion of a metal of the component to form an intermediate and a reduced metal of said component at a surface of the molten metal bath which is in contact with the waste component phase, and wherein both the metal oxide and the reduced metal dissolve in the molten metal bath; and b) directing a second reducing agent into the molten metal bath to chemically reduce the metal of the intermediate at a rate comparable to that of the dissolution of the reduced metal of the waste component into the molten metal bath.
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35. A method for chemically remediating a metal component of a metal-containing waste, comprising the steps of:
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a) directing the waste into a molten metal bath which includes a first reducing agent that, under the operating conditions of the molten metal bath, chemically reduces said component containing the metal contaminant of the metal-containing waste to form a metal-containing intermediate and a reduced metal component of the waste; b) exposing the metal of the metal-containing intermediate to a second reducing agent in the molten metal bath which, under the operating conditions of the bath, reduces said metal 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-containing intermediate formed to dissolve in the molten metal bath; and
thereafterc) reclaiming the reduced metal component of the waste from the molten metal bath.
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Specification