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Patent Number: |
7524794 |
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Case ID: |
0 |
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Patent Title:
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Method for surface treating perlite sorbents for improved adsorbing of
vapor phase metals and metal compounds at elevated temperatures
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Status: |
ACTIVE |
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Status Date: |
10/12/2009 7:36:32 AM |
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Issue Date:
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4/28/2009 |
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Filed Date:
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9/1/2004 |
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Serial #:
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0/931,232 |
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Assignee Name:
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The United States of America as represented by the Secretary of the Army
(Washington,
DC)
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Inventor(s):
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Boddu, Veera M. , Hay, Kent James , Ghosh, Tushar K. , Viswanath, Dabir S. |
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BACKGROUND
The amount of heavy metals contained in flue gases released from high temperature incinerators, such as demilitarization furnaces operated by the U.S. Government and its contractors, are monitored and controlled in accordance with EPA
regulations. A typical air pollution control technique is to inject activated carbon or its modified form (activated carbon impregnated with various chemicals) as sorbents into the flue gas or the combustion chamber to capture the metal vapors. The
carbon is then separated from the flue gas in a downstream filter system. Chen, S., Rostam-Abadi, M., and R. Chang. An Evaluation of Carbon-Based Processes for Combined Hg/SO2/Nox Removal from Coal Combustion Flue Gasses, Book of Abstracts, 216.sup.th
ACS National Meeting, Boston, Aug. 23-27, 1998.
As an example, the U.S. Army operates and maintains deactivation furnaces for conventional and chemical munitions demilitarization operations. These furnaces are subject to the Haza . . . . More |
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Perlite, particularly, perlite in powdered form, is employed to adsorb
metals and metal compounds from a fluid flow. In select embodiments, the
perlite is treated to expand its surface area and injected into a fluid
stream, such as flue gas, held for a specific retention period, and
removed for subsequent disposal. In other embodiments the perlite is
provided in a fixed adsorption bed and the fluid flow permitted to pass
through the bed until the perlite surface is exhausted. The perlite in
the fixed bed is then replaced, with the exhausted perlite disposed of as
appropriate. Treatment of perlite by boiling with sulfuric acid or
suspending in a suspension of sulfur in carbon disulfide has been shown
to significantly expand the surface area of perlite.
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We claim:
1. A method for modifying expanded perlite thereby enabling use of said modified expanded perlite to efficiently adsorb unwanted vapor phase metals and metal compounds in fluids,
comprising: providing a pre-specified amount of expanded perlite; combining said pre-specified amount of expanded perlite with a pre-specified amount of a material suitable for interacting with said perlite to surface treat said expanded perlite;
boiling said combination of said material and said expanded perlite for a pre-specified period; cooling said boiled combination to a first pre-specified temperature; filtering said cooled combination to yield a filtrate; washing said filtrate with
distilled water until said filtrate attains an approximately neutral pH to yield a neutralized filtrate; and drying said neutralized filtrate in an oven at a second pre-specified temperature to yield said surface treated expanded perlite.
2. The method of claim 1 in which said material is a . . . . More |
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