Download or read book Alternative Enhanced Chemical Cleaning Basic Studies Results FY09 written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to the need to close waste storage tanks, chemical cleaning methods are needed for the effective removal of the heels. Oxalic acid is the preferred cleaning reagent for sludge heel dissolution, particularly for iron-based sludge, due to the strong complexing strength of the oxalate. However, the large quantity of oxalate added to the tank farm from oxalic acid based chemical cleaning has significant downstream impacts. Optimization of the oxalic acid cleaning process can potentially reduce the downstream impacts from chemical cleaning. To optimize oxalic acid usage, a detailed understanding of the chemistry of oxalic acid based sludge dissolution is required. Additionally, other acid systems may be required for specific waste components with low solubility in oxalic acid and as a means to reduce oxalic acid usage in general. Solubility tests were conducted using non-radioactive, pure metal phases known to be the primary phases present in High Level Waste sludge. The metal phases studied included the aluminum phases gibbsite and boehmite and the iron phases magnetite and hematite. Hematite and boehmite are expected to be the most difficult iron and aluminum phases to dissolve. These mineral phases have been identified in both SRS and Hanford High Level Waste sludge. Acids evaluated for dissolution included oxalic, nitric, and sulfuric acids. The results of the solubility tests indicate that oxalic and sulfuric acids are more effective for the dissolution of the primary sludge phases. For boehmite, elevated temperature will be required to promote effective phase dissolution in the acids studied. Literature reviews, thermodynamic modeling, and experimental results have all confirmed that pH control using a supplemental proton source (additional acid) is critical for minimization of oxalic acid usage during the dissolution of hematite. These results emphasize the importance of pH control in optimizing hematite dissolution in oxalic acid and may explain the somewhat limited success observed during recent attempts to remove sludge heels from SRS Tanks 5F and 6F using oxalic acid. Additionally, based on the results of the solubility tests conducted, the following conclusions can be drawn: (1) Hematite dissolution in oxalic acid is a stoichiometric process dependant upon the provision of sufficient oxalate molar equivalents to complex the iron and sufficient H to promote the dissolution reaction. (2) The optimal utilization of oxalic acid for hematite dissolution requires an additional proton source, such as nitric acid, and a pH of (less-than or equal to) 1. In the absence of a supplemental proton source, greater than stoichiometric amounts of oxalate are required. (3) Magnetite is generally more soluble than hematite in all acids tested. (4) Gibbsite is generally more soluble than the boehmite form of aluminum in all acids tested. (5) The OLI Thermodynamic Model is a useful tool for the prediction of equilibrium iron concentrations, but predictions must be experimentally verified. The OLI model appears to over-predict the solubility of the iron and aluminum phases studied in mineral acids.

Download or read book Alternative and Enhanced Chemical Cleaning written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In an effort to develop and optimize chemical cleaning methods for the removal of sludge heels from High Level Waste tanks, solubility tests have been conducted using nonradioactive, pure metal phases. The metal phases studied included the aluminum phase gibbsite and the iron phases hematite, maghemite, goethite, lepidocrocite, magnetite, and wustite. Many of these mineral phases have been identified in radioactive, High Level Waste sludge at the Savannah River and Hanford Sites. Acids evaluated for dissolution included oxalic, nitric, and sulfuric acids and a variety of other complexing organic acids. The results of the solubility tests indicate that mixtures of oxalic acid with either nitric or sulfuric acid are the most effective cleaning solutions for the dissolution of the primary metal phases in sludge waste. Based on the results, optimized conditions for hematite dissolution in oxalic acid were selected using nitric or sulfuric acid as a supplemental proton source. Electrochemical corrosion studies were also conducted (reported separately; Wiersma, 2010) with oxalic/mineral acid mixtures to evaluate the effects of these solutions on waste tank integrity. The following specific conclusions can be drawn from the test results: (1) Oxalic acid was shown to be superior to all of the other organic acids evaluated in promoting the dissolution of the primary sludge phases. (2) All iron phases showed similar solubility trends in oxalic acid versus pH, with hematite exhibiting the lowest solubility and the slowest dissolution. (3) Greater than 90% hematite dissolution occurred in oxalic/nitric acid mixtures within one week for two hematite sources and within three weeks for a third hematite sample with a larger average particle size. This dissolution rate appears acceptable for waste tank cleaning applications. (4) Stoichiometric dissolution of iron phases in oxalic acid (based on the oxalate concentration) and the formation of the preferred 1:1 Fe to oxalate complex is possible with the addition of a supplemental hydrogen ion source (HNO3 or H2SO4) and pH control. (5) Sulfuric acid is nearly twice as effective as nitric acid (on a molar basis) at promoting hematite dissolution in oxalic acid solutions, most likely due to the fact that it is diprotic. (6) The greater the oxalic acid concentration, the greater the demand for supplemental H to promote optimal dissolution. Minimum mineral acid concentrations required for optimal oxalic acid utilization based on hematite solubility tests are provided. (7) Corrosion studies conducted (reported elsewhere) with 1 wt.% oxalic acid revealed that carbon steel corrosion rates are manageable at lower mineral acid concentrations (0.1 M HNO3 and 0.05 M H2SO4) and lower temperatures (45 C). (8) Proposed conditions for waste tank heel dissolution based on the solubility and corrosion test results are 0.5 wt.% oxalic acid and 0.18 M HNO3 or 0.09 M H2SO4 at 50 C. (9) The OLI Thermodynamic Model appears to over-predict the solubility of the iron phases studied in oxalic acid and oxalic/nitric acid mixtures. The predictions show better agreement with experimental results at higher pH and in sulfuric/oxalic acid mixtures. (10) Oxalic, nitric, and sulfuric acids are effective at quickly dissolving gibbsite (e"6% dissolution in 2 weeks), with oxalic/sulfuric acid mixtures being particularly effective. (11) Limited dissolution tests conducted with carbon steel coupons revealed that the presence of metallic iron can, in some cases, result in dramatically different results. Additional studies in this area are recommended. Based on the current results, the optimal approach for the removal of sludge heels for HLW tanks would include the following steps: (1) removal of the maximum possible amount of heel materials by mechanical means; (2) neutralization and acidification of the heel using dilute mineral acid (This step should promote significant dissolution of certain metal hydroxides and salts, including gibbsite.); and (3) dissolution of the residual heel material at 50 C using an acid mixture containing 0.5 wt.% oxalic acid and 0.18 M nitric acid (This step should dissolve the iron phases.).

Download or read book EM 31 Alternative and Enhanced Chemical Cleaning Program written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: King's introduction to his presentation made 5 important points: 1) Numerous SRS tanks scheduled for closure (contract commitments); 2) Cannot remove all sludge by mechanical means due to obstructions; 3) Chemical removal technology needed (likely oxalic acid); 4) Post - dissolution neutralization required prior to transfer to compliant tanks; 5) Sodium oxalate salts precipitate on neutralization and have negative downstream impacts. There were three SRS chemical cleaning programs in 2010: Baseline: 8wt percent OA batch contact, ECC: 1-3 wt. percent OA with oxalate destruction, and the Alternative/Enhanced Chemical Cleaning (EM-31). This talk is on the EM-31 program.

Download or read book EM 21 ALTERNATIVE ENHANCED CHEMICAL CLEANING PROGRAM FOR SLUDGE HEEL REMOVAL written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Preliminary studies in the EM-21 Alternative Chemical Cleaning Program have focused on understanding the dissolution of Hematite (a primary sludge heel phase) in oxalic acid, with a focus on minimizing oxalic acid usage. Literature reviews, thermodynamic modeling, and experimental results have all confirmed that pH control, preferably using a supplemental proton source, is critical to oxalate minimization. With pH control, iron concentrations as high as 0.103 M have been obtained in 0.11 M oxalic acid. This is consistent with the formation of a 1:1 (iron:oxalate) complex. The solubility of Hematite in oxalic acid has been confirmed to increase by a factor of 3 when the final solution pH decreases from 5 to below 1. This is consistent with literature predictions of a shift in speciation from a 1:3 to 1:1 as the pH is lowered. Above a solution pH of 6, little Hematite dissolves. These results emphasize the importance of pH control in optimizing Hematite dissolution in oxalic acid.

Download or read book ALTERNATIVE AND ENHANCED CHEMICAL CLEANING written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to the need to close High Level Waste storage tanks, chemical cleaning methods are needed for the removal of sludge heel materials remaining at the completion of mechanical tank cleaning efforts. Oxalic acid is considered the preferred cleaning reagent for heel dissolution of iron-based sludge. However, the large quantity of chemical reagents added to the tank farm from oxalic acid based cleaning has significant downstream impacts. Optimization of the oxalic acid cleaning process can potentially reduce the downstream impacts from chemical cleaning. To optimize oxalic acid usage, a detailed understanding of the chemistry of oxalic acid based sludge dissolution is required. Additionally, other acidic systems may be required for specific waste components that have low solubility in oxalic acid, and as a means to reduce oxalic acid usage in general. Electrochemical corrosion studies were conducted with 1 wt. % oxalic acid at mineral acid concentrations above and below the optimal conditions for this oxalic acid concentration. Testing environments included pure reagents, pure iron and aluminum phases, and sludge simulants. Mineral acid concentrations greater than 0.2 M and temperatures greater than 50 C result in unacceptably high corrosion rates. Results showed that manageable corrosion rates of carbon steel can be achieved at dilute mineral acid concentrations (i.e. less than 0.2 M) and low temperatures based on the contact times involved. Therefore, it is recommended that future dissolution and corrosion testing be performed with a dilute mineral acid and a less concentrated oxalic acid (e.g., 0.5 wt.%) that still promotes optimal dissolution. This recommendation requires the processing of greater water volumes than those for the baseline process during heel dissolution, but allows for minimization of oxalic acid additions. The following conclusions can be drawn from the test results: (1) In both nitric and sulfuric acid based reagents, the low temperature and dilute concentration environment resulted in carbon steel corrosion rates that were less than 150 mpy. These rates are manageable in that chemical cleaning processes could proceed for limited time without significant wall loss. Further optimization of the Alternative Enhance Chemical Cleaning (AECC) process should focus on testing in solutions of this dilute concentration and low temperature regime. (2) In general, for the nitric acid based reagent, the aluminum oxide phase environments resulted in higher corrosion rates than the iron oxide phase environments. (3) In general, for the sulfuric acid based reagent, the iron oxide phase environments resulted in higher corrosion rates than the aluminum oxide phase environments. (4) In general, for the nitric acid based reagent, the HM sludge simulant environments resulted in higher corrosion rates than the PUREX sludge simulant environments. This result agrees with the previous observation that the aluminum oxide phases are more aggressive than the iron oxide phase environments in the nitric acid reagent. (5) Pitting was more likely to occur in the sulfuric acid based reagents than in the nitric acid based reagents. (6) Pitting occurred only in the iron based pure oxide phases and the sludge simulants. No pitting was observed in the aluminum based pure oxide phases. (7) Pitting tended to occur more frequently in tests that involved the dilute mineral acid reagent. (8) Pitting was more severe at the higher temperature for a given mineral acid concentration. (9) Pitting was more severe at a higher mineral acid concentration for a given temperature. (10) Based on the combined results of the open circuit potential and cathodic polarization testing, there was a low propensity for hydrogen evolution in solutions where sludge has been dissolved.

Download or read book EM 31 ALTERNATIVE AND ENHANCED CHEMICAL CLEANING PROGRAM FOR SLUDGE HEEL REMOVAL 11220 written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Mixtures of oxalic acid with nitric acid have been shown to be superior to oxalic acid alone for the dissolution of iron-rich High Level Waste sludge heels. Optimized conditions resulting in minimal oxalate usage and stoichiometric iron dissolution (based on added oxalate ion) have been determined for hematite (a primary sludge iron phase) in oxalic/nitric acid mixtures. The acid mixtures performed better than expected based on the solubility of hematite in the individual acids through a synergistic effect in which the preferred 1:1 Fe:oxalate complex is formed. This allows for the minimization of oxalate additions to the waste stream. Carbon steel corrosion rates were measured in oxalic/nitric acid mixtures to evaluate the impacts of chemical cleaning with these solutions on waste tank integrity. Manageable corrosion rates were observed in the concentration ranges of interest for an acid contact timescale of 1 month. Kinetics tests involving hematite and gibbsite (a primary sludge aluminum phase) have confirmed that ≥90% solids dissolution occurs within 3 weeks. Based on these results, the chemical cleaning conditions recommended to promote minimal oxalate usage and manageable corrosion include: 0.5 wt. % oxalic acid/0.175 M nitric acid mixture, 50 C, 2-3 week contact time with agitation.

Download or read book REVIEW OF ALTERNATIVE ENHANCED CHEMICAL CLEANING OPTIONS FOR SRS WASTE TANKS written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A literature review was conducted to support the Task Technical and Quality Assurance Plan for Alternative Enhanced Chemical Cleaning (AECC) for sludge heel removal funded as part of the EM-21 Engineering and Technology program. The goal was to identify potential technologies or enhancements to the baseline oxalic acid cleaning process for chemically dissolving or mobilizing Savannah River Site (SRS) sludge heels. The issues with the potentially large volume of oxalate solids generated from the baseline process have driven an effort to find an improved or enhanced chemical cleaning technology for the tank heels. This literature review builds on a previous review conducted in 2003. A team was charged with evaluating the information in these reviews and developing recommendations of alternative technologies to pursue. The new information in this report supports the conclusion of the previous review that oxalic acid remains the chemical cleaning agent of choice for dissolving the metal oxides and hydroxides found in sludge heels in carbon steel tanks. The potential negative impact of large volumes of sodium oxalate on downstream processes indicates that the amount of oxalic acid used for chemical cleaning needs to be minimized as much as possible or the oxalic acid must be destroyed prior to pH adjustment in the receipt tank. The most straightforward way of minimizing the volume of oxalic acid needed for chemical cleaning is through more effective mechanical cleaning. Using a mineral acid to adjust the pH of the sludge prior to adding oxalic acid may also help to minimize the volume of oxalic acid used in chemical cleaning. If minimization of oxalic acid proves insufficient in reducing the volume of oxalate salts, several methods were found that could be used for oxalic acid destruction. For some waste tank heels, another acid or even caustic treatment (or pretreatment) might be more appropriate than the baseline oxalic acid cleaning process. Caustic treatment of high aluminum sludge heels may be appropriate as a means of reducing oxalic acid usage. Reagents other than oxalic acid may also be needed for removing actinide elements from the tank heels. A systems engineering evaluation (SEE) was performed on the various alternative chemical cleaning reagents and organic oxidation technologies discussed in the literature review. The objective of the evaluation was to develop a short list of chemical cleaning reagents and oxalic acid destruction methods that should be the focus of further research and development. The results of the SEE found that eight of the thirteen organic oxidation technologies scored relatively close together. Six of the chemical cleaning reagents were also recommended for further investigation. Based on the results of the SEE and plan set out in the TTQAP the following broad areas are recommended for future study as part of the AECC task: (1) Basic Chemistry of Sludge Dissolution in Oxalic Acid: A better understanding of the variables effecting dissolution of sludge species is needed to efficiently remove sludge heels while minimizing the use of oxalic acid or other chemical reagents. Tests should investigate the effects of pH, acid concentration, phase ratios, temperature, and kinetics of the dissolution reactions of sludge components with oxalic acid, mineral acids, and combinations of oxalic/mineral acids. Real waste sludge samples should be characterized to obtain additional data on the mineral phases present in sludge heels. (2) Simulant Development Program: Current sludge simulants developed by other programs for use in waste processing tests, while compositionally similar to real sludge waste, generally have more hydrated forms of the major metal phases and dissolve more easily in acids. Better simulants containing the mineral phases identified by real waste characterization should be developed to test chemical cleaning methods. (3) Oxalic Acid Oxidation Technologies: The two Mn based oxidation methods that scored highly in the SEE should be studied to evaluate long term potential. One of the AOP's (UV/O3/Solids Separator) is currently being implemented by the SRS liquid waste organization for use in tank heel chemical cleaning. (4) Corrosion Issues: A program will be needed to address potential corrosion issues from the use of low molarity mineral acids and mixtures of oxalic/mineral acids in the waste tanks for short durations. The addition of corrosion inhibitors to the acids to reduce corrosion rates should be investigated.

Download or read book Developments in Surface Contamination and Cleaning Methods for Surface Cleaning written by Rajiv Kohli and published by William Andrew. This book was released on 2016-11-04 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: Developments in Surface Contamination and Cleaning: Methods for Surface Cleaning, Volume 9, part of the Developments in Surface Contamination and Cleaning series provide a state-of-the-art guide to the current knowledge on the behavior of film-type and particulate surface contaminants and their associated cleaning methods. This newest volume in the series discusses methods of surface cleaning of contaminants and the resources that are needed to deal with them. Taken as a whole, the series forms a unique reference for professionals and academics working in the area of surface contamination and cleaning. A strong theme running through the series is that of surface contamination and cleaning at the micro and nano scales. Provides a comprehensive coverage of innovations in surface cleaning Written by established experts in the surface cleaning field, presenting an authoritative resource Contains a comprehensive review of the state-of-the-art, including case studies to enhance the learning process

Download or read book Developments in Surface Contamination and Cleaning Applications of Cleaning Techniques written by Rajiv Kohli and published by Elsevier. This book was released on 2018-11-27 with total page 830 pages. Available in PDF, EPUB and Kindle. Book excerpt: Developments in Surface Contamination and Cleaning: Applications of Cleaning Techniques, Volume Eleven, part of the Developments in Surface Contamination and Cleaning series, provides a guide to recent advances in the application of cleaning techniques for the removal of surface contamination in various industries, such as aerospace, automotive, biomedical, defense, energy, manufacturing, microelectronics, optics and xerography. The material in this new edition compiles cleaning applications into one easy reference that has been fully updated to incorporate new applications and techniques. Taken as a whole, the series forms a unique reference for professionals and academics working in the area of surface contamination and cleaning. Presents the latest reviewed technical information on precision cleaning applications as written by established experts in the field Provides a single source on the applications of innovative precision cleaning techniques for a wide variety of industries Serves as a guide to the selection of precision cleaning techniques for specific applications

Download or read book Alternatives for CFC 113 and Methyl Chloroform in Metal Cleaning written by and published by . This book was released on 1991 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Environmental Issues in the Electronics and Semiconductor Industries written by Electrochemical Society. Dielectric Science and Technology Division and published by The Electrochemical Society. This book was released on 1999 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Demonstration of Alternative Cleaning Systems written by Dean M. Menke and published by . This book was released on 1995 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Guide to Cleaner Technologies written by and published by . This book was released on 1994 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nuclear Waste written by David C. Trimble and published by DIANE Publishing. This book was released on 2011-05 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: Decades of nuclear materials production at the Dept. of Energy¿s (DoE) Savannah River Site in S. Carolina have left 37 million gallons of radioactive liquid waste in 49 underground storage tanks. In Dec. 2008, DoE entered into a contract with Savannah River Remediation, LLC (SRR) to close, by 2017, 22 of the highest-risk tanks at a cost of $3.2 billion. This report assessed: (1) DoE¿s cost estimates and schedule for closing the tanks at the Savannah River Site; and (2) the primary challenges, if any, to closing the tanks and the steps DoE has taken to address them. The auditor visited the Savannah River Site and reviewed tank closure documents. Includes recommendations. Charts and tables. This is a print on demand report.

Download or read book Alternatives for Ground Water Cleanup written by National Research Council and published by National Academies Press. This book was released on 1994-02-01 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt: There may be nearly 300,000 waste sites in the United States where ground water and soil are contaminated. Yet recent studies question whether existing technologies can restore contaminated ground water to drinking water standards, which is the goal for most sites and the result expected by the public. How can the nation balance public health, technological realities, and cost when addressing ground water cleanup? This new volume offers specific conclusions, outlines research needs, and recommends policies that are technologically sound while still protecting health and the environment. Authored by the top experts from industry and academia, this volume: Examines how the physical, chemical, and biological characteristics of the subsurface environment, as well as the properties of contaminants, complicate the cleanup task. Reviews the limitations of widely used conventional pump-and-treat cleanup systems, including detailed case studies. Evaluates a range of innovative cleanup technologies and the barriers to their full implementation. Presents specific recommendations for policies and practices in evaluating contamination sites, in choosing remediation technologies, and in setting appropriate cleanup goals.

Download or read book Guide to Cleaner Technologies written by and published by . This book was released on 1994 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Greenhouse Gas Control Technologies 6th International Conference written by John Gale and published by Elsevier. This book was released on 2003-08-05 with total page 957 pages. Available in PDF, EPUB and Kindle. Book excerpt: Climate change is an issue that is highly debated around the globe. This book brings together the papers that were presented at a conference dedicated to this issue, held in Kyoto in October 2002. Covering a broad range of areas, the topics presented will benefit both those working in the field of carbon dioxide recovery and sequestration, and those looking at the effects of non carbon dioxide greenhouse gases. An overview of the Research and Design technologies which aid in mitigating climate change is included, which will be invaluable to those researching new opportunities for dealing with this problem. An area of research that has seen a rapid rise in worldwide spend Will benefit both researchers in climate change, and those looking at new technologies to help deal with the problem Presents papers from contributors spread around the globe means that this book has world wide relevance