skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: REMOVING SLUDGE HEELS FROM SAVANNAH RIVER SITE WASTE TANKS BY OXALIC ACID DISSOLUTION

Abstract

The Savannah River Site (SRS) will remove sludge as part of waste tank closure operations. Typically the bulk sludge is removed by mixing it with supernate to produce a slurry, and transporting the slurry to a downstream tank for processing. Experience shows that a residual heel may remain in the tank that cannot be removed by this conventional technique. In the past, SRS used oxalic acid solutions to disperse or dissolve the sludge heel to complete the waste removal. To better understand the actual conditions of oxalic acid cleaning of waste from carbon steel tanks, the authors developed and conducted an experimental program to determine its effectiveness in dissolving sludge, the hydrogen generation rate, the generation rate of other gases, the carbon steel corrosion rate, the impact of mixing on chemical cleaning, the impact of temperature, and the types of precipitates formed during the neutralization process. The test samples included actual SRS sludge and simulated SRS sludge. The authors performed the simulated waste tests at 25, 50, and 75 C by adding 8 wt % oxalic acid to the sludge over seven days. They conducted the actual waste tests at 50 and 75 C by adding 8 wt % oxalicmore » acid to the sludge as a single batch. Following the testing, SRS conducted chemical cleaning with oxalic acid in two waste tanks. In Tank 5F, the oxalic acid (8 wt %) addition occurred over seven days, followed by inhibited water to ensure the tank contained enough liquid to operate the mixer pumps. The tank temperature during oxalic acid addition and dissolution was approximately 45 C. The authors analyzed samples from the chemical cleaning process and compared it with test data. The conclusions from the work are: (1) Oxalic acid addition proved effective in dissolving sludge heels in the simulant demonstration, the actual waste demonstration, and in SRS Tank 5F. (2) The oxalic acid dissolved {approx} 100% of the uranium, {approx} 100% of the iron, and {approx} 40% of the manganese during a single contact in the simulant demonstration. (The iron dissolution may be high due to corrosion of carbon steel coupons.) (3) The oxalic acid dissolved {approx} 80% of the uranium, {approx} 70% of the iron, {approx} 50% of the manganese, and {approx} 90% of the aluminum in the actual waste demonstration for a single contact. (4) The oxalic acid dissolved {approx} 100% of the uranium, {approx} 15% of the iron, {approx} 40% of the manganese, and {approx} 80% of the aluminum in Tank 5F during the first contact cycle. Except for the iron, these results agree well with the demonstrations. The data suggest that a much larger fraction of the iron in the sludge dissolved, but it re-precipitated with the oxalate added to Tank 5F. (5) The demonstrations produced large volumes (i.e., 2-14 gallons of gas/gallon of oxalic acid) of gas (primarily carbon dioxide) by the reaction of oxalic acid with sludge and carbon steel. (6) The reaction of oxalic acid with carbon steel produced hydrogen in the simulant and actual waste demonstrations. The volume produced varied from 0.00002-0.00100 ft{sup 3} hydrogen/ft{sup 2} carbon steel. The hydrogen production proved higher in unmixed tanks than in mixed tanks.« less

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
SRS
Sponsoring Org.:
USDOE
OSTI Identifier:
944813
Report Number(s):
SRNL-STI-2008-00466
TRN: US200902%%971
DOE Contract Number:  
DE-AC09-08SR22470
Resource Type:
Conference
Resource Relation:
Conference: Waste Management 2009 Conference
Country of Publication:
United States
Language:
English
Subject:
08 HYDROGEN; 36 MATERIALS SCIENCE; ALUMINIUM; CARBON DIOXIDE; CARBON STEELS; CLEANING; DISSOLUTION; HYDROGEN; HYDROGEN PRODUCTION; IRON; MANGANESE; OXALATES; OXALIC ACID; SLUDGES; TANKS; URANIUM; WASTE MANAGEMENT; WASTES

Citation Formats

Poirier, M, David Herman, D, Fernando Fondeur, F, John Pareizs, J, Michael Hay, M, Bruce Wiersma, B, Kim Crapse, K, Thomas Peters, T, Samuel Fink, S, and Donald Thaxton, D. REMOVING SLUDGE HEELS FROM SAVANNAH RIVER SITE WASTE TANKS BY OXALIC ACID DISSOLUTION. United States: N. p., 2009. Web.
Poirier, M, David Herman, D, Fernando Fondeur, F, John Pareizs, J, Michael Hay, M, Bruce Wiersma, B, Kim Crapse, K, Thomas Peters, T, Samuel Fink, S, & Donald Thaxton, D. REMOVING SLUDGE HEELS FROM SAVANNAH RIVER SITE WASTE TANKS BY OXALIC ACID DISSOLUTION. United States.
Poirier, M, David Herman, D, Fernando Fondeur, F, John Pareizs, J, Michael Hay, M, Bruce Wiersma, B, Kim Crapse, K, Thomas Peters, T, Samuel Fink, S, and Donald Thaxton, D. Sun . "REMOVING SLUDGE HEELS FROM SAVANNAH RIVER SITE WASTE TANKS BY OXALIC ACID DISSOLUTION". United States. https://www.osti.gov/servlets/purl/944813.
@article{osti_944813,
title = {REMOVING SLUDGE HEELS FROM SAVANNAH RIVER SITE WASTE TANKS BY OXALIC ACID DISSOLUTION},
author = {Poirier, M and David Herman, D and Fernando Fondeur, F and John Pareizs, J and Michael Hay, M and Bruce Wiersma, B and Kim Crapse, K and Thomas Peters, T and Samuel Fink, S and Donald Thaxton, D},
abstractNote = {The Savannah River Site (SRS) will remove sludge as part of waste tank closure operations. Typically the bulk sludge is removed by mixing it with supernate to produce a slurry, and transporting the slurry to a downstream tank for processing. Experience shows that a residual heel may remain in the tank that cannot be removed by this conventional technique. In the past, SRS used oxalic acid solutions to disperse or dissolve the sludge heel to complete the waste removal. To better understand the actual conditions of oxalic acid cleaning of waste from carbon steel tanks, the authors developed and conducted an experimental program to determine its effectiveness in dissolving sludge, the hydrogen generation rate, the generation rate of other gases, the carbon steel corrosion rate, the impact of mixing on chemical cleaning, the impact of temperature, and the types of precipitates formed during the neutralization process. The test samples included actual SRS sludge and simulated SRS sludge. The authors performed the simulated waste tests at 25, 50, and 75 C by adding 8 wt % oxalic acid to the sludge over seven days. They conducted the actual waste tests at 50 and 75 C by adding 8 wt % oxalic acid to the sludge as a single batch. Following the testing, SRS conducted chemical cleaning with oxalic acid in two waste tanks. In Tank 5F, the oxalic acid (8 wt %) addition occurred over seven days, followed by inhibited water to ensure the tank contained enough liquid to operate the mixer pumps. The tank temperature during oxalic acid addition and dissolution was approximately 45 C. The authors analyzed samples from the chemical cleaning process and compared it with test data. The conclusions from the work are: (1) Oxalic acid addition proved effective in dissolving sludge heels in the simulant demonstration, the actual waste demonstration, and in SRS Tank 5F. (2) The oxalic acid dissolved {approx} 100% of the uranium, {approx} 100% of the iron, and {approx} 40% of the manganese during a single contact in the simulant demonstration. (The iron dissolution may be high due to corrosion of carbon steel coupons.) (3) The oxalic acid dissolved {approx} 80% of the uranium, {approx} 70% of the iron, {approx} 50% of the manganese, and {approx} 90% of the aluminum in the actual waste demonstration for a single contact. (4) The oxalic acid dissolved {approx} 100% of the uranium, {approx} 15% of the iron, {approx} 40% of the manganese, and {approx} 80% of the aluminum in Tank 5F during the first contact cycle. Except for the iron, these results agree well with the demonstrations. The data suggest that a much larger fraction of the iron in the sludge dissolved, but it re-precipitated with the oxalate added to Tank 5F. (5) The demonstrations produced large volumes (i.e., 2-14 gallons of gas/gallon of oxalic acid) of gas (primarily carbon dioxide) by the reaction of oxalic acid with sludge and carbon steel. (6) The reaction of oxalic acid with carbon steel produced hydrogen in the simulant and actual waste demonstrations. The volume produced varied from 0.00002-0.00100 ft{sup 3} hydrogen/ft{sup 2} carbon steel. The hydrogen production proved higher in unmixed tanks than in mixed tanks.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2009},
month = {3}
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share: