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1
Bergsten, Joshua. "Sorption and leaching characteristics of heavy metals in artificial soil". Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4617.
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Thesis (M.S.) University of Missouri-Columbia, 2006.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 21, 2007) Includes bibliographical references.
2
Yang, Xinbo. "LEACHING CHARACTERISTICS OF RARE EARTH ELEMENTS FROM BITUMINOUS COAL-BASED SOURCES". UKnowledge, 2019. https://uknowledge.uky.edu/mng_etds/49.
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The demand for rare earth elements (REEs) has increased over the last decade due to applications in high technology devices including those in the defense industry. The recovery of REEs from primary sources such as rare earth minerals are viable using physical separations followed by chemical processing. However, weak market values and environmental concerns have limited the viability of such operations. On the other hand, REE recovery from secondary sources such as apatite ore, bauxite waste, and waste recycling, provides an opportunity to take advantage of a resource that does not require mining costs as well as other associated costs given that these expenses are covered by the revenue generated from the production of the primary material. Coal-based materials represent a potential source for REEs which may be extracted and concentrated by the use of physical and/or chemical processes.
The current study focused on developing a leaching process to extract REEs from the pre-combustion coal sources including coarse and fine refuse and low-valued material obtained from coal preparation plants. Materials collected for leaching characteristic studies were found to have average total REE concentrations in the range of 200-350 ppm on a whole sample basis. Mineralogy studies performed on Fire Clay seam coal refuse using SEM-EDS detected micro-dispersed rare earth phosphate mineral particles which are generally difficult to dissolve in strong acid solutions. On the other hand, XRD analysis results from a high REE content segment of the West Kentucky No. 13 coal seam indicated the presence of fluorapatite which is soluble in weak acid solutions. The mineral associations of REEs were studied by extracting REEs using different types of acids under various pH conditions. Differential extraction of the REEs was examined along with the associated impurity elements such as iron, aluminum, and calcium among others. The findings showed that the light REEs were primarily associated in a phosphate mineral form, whereas the heavy REEs were mostly present in an ion substitution form associated with clay minerals.
Relatively high concentrations of REEs were discovered in mixed-phase particles consisting of both coal and mineral matter. By reducing the particle size, more leachable forms of REEs were liberated and recovered along with the associated mineral matter embedded in the coal structure. The type of lixiviant played an important role during the initial stage of leaching but was found to be insignificant as the system reached equilibrium. Solids concentration in the leaching medium has an important role in establishing the throughput capacity of the leaching system. Test results found that an increase in solids concentration had a significant negative effect on rare earth recovery. This finding may be explained by higher concentrations of soluble calcium-based minerals such as calcite which provided localized pH increases near and within the pores of the solids. The result was precipitation of CaSO4 within the pores which blocked access for the lixiviants. This hypothesis was supported by the findings from BET and XPS analyses which found lower pore volume in high solid concentration systems and the existence of CaSO4 on the surface of the solids.
Leaching test results obtained using sulfuric acid over a range of temperatures showed that the leaching process was mainly driven by a diffusion control process. The activation energy determined for an Illinois No. 6 coal source was 14.6 kJ/mol at the beginning of the reaction and 35.9 kJ/mol for the rest of the leaching process up to 2 hours. For material collected from the Fire Clay coal seam, the apparent activation energy was 36 kJ/mol at the start of the leaching reaction and decreased to 27 kJ/mol over the remaining period of the test. The activation energy values were nearly equivalent to the upper-level values that generally define a diffusion control process and the lower values of a chemical reaction control process. The lack of clarity in defining a clear control mechanism is likely associated with the variability in associated mineralogy, various modes of occurrence of the REEs and the interfacial transfer of product through the porous structure of the coal-based particles which requires relatively high activation energy. As such, both diffusion control and chemical reaction control mechanisms are likely occurring simultaneously during the leaching process with diffusion control being more dominant.
3
Scherer, T., D. Slack, J. Watson i F. Fox. "Comparison of Three Irrigation Scheduling Methods and Evaluation of Irrigation Leaching Characteristics". College of Agriculture, University of Arizona (Tucson, AZ), 1989. http://hdl.handle.net/10150/204858.
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Three methods were used to schedule irrigations on replicated plots at the Maricopa Ag Center using DPL 90 cotton. The three methods were: a soil water balance model based on historic consumptive use curves, a soil water balance model based on the Modified Penman Equation and daily weather (AZMET), and infrared thermometry using the C.W.S.I. A potassium-bromide conservative tracer was applied at selected sites in the plots to evaluate leaching characteristics. The irrigation scheduling test was duplicated at the Safford Experiment Station and is presented in another report. Results from the 1988 data indicate that there was no significant difference in yield between the 3 methods. There was a significant difference in water applied; the historic consumptive-use curves was the lowest and the Penman equation method was the highest.
4
Scherer, T., D. Slack, J. Watson i F. Fox. "Comparison of Three Irrigation Scheduling Methods and Evaluation of Irrigation Leaching Characteristics". College of Agriculture, University of Arizona (Tucson, AZ), 1990. http://hdl.handle.net/10150/208305.
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Three methods were used to schedule irrigations during 1989 on replicated plots at the Maricopa Ag Center using DPL 90 cotton. This is a continuation of the research initiated in 1988 using the same field The three methods were; a soil water balance model based on historic consumptive use curves, a soil water balance model based on the Modified Penman Equation and daily weather (AZMET), and infrared thermometry using the C.W.S.I. A potassium- bromide conservative tracer was applied at selected sites in the plots to evaluate leaching characteristics. The irrigation scheduling test was again duplicated at the Safford Experiment Station and is presented in another report. Results from this years data indicate that there was no significant difference in yield among the three methods. However, as in 1988 there was a significant difference in water applied with historic consumptive use (ERIE) the lowest and the Penman equation method (CHECKBOOK) the highest.
5
Scherer, Tom, Don Slack, Jack Watson i Fred Fox. "Comparison of Three Irrigation Scheduling Methods and Evaluation of Irrigation Leaching Characteristics". College of Agriculture, University of Arizona (Tucson, AZ), 1991. http://hdl.handle.net/10150/208344.
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Three methods were used to schedule irrigations during the 1990 growing season on replicated plots at the Maricopa Ag Center using DPL 90 cotton. This is the final report of the research initiated in 1988. The three methods were: a soil water balance model based on historic consumptive use curves (ERIE), a soil water balance model (AZSCHED) based on the Modified Penman Equation and daily weather (AZMET), and infrared thermometry using the Crop Water Stress Index (CWSI). A potassium- bromide conservative tracer was applied at selected sites in the plots to evaluate leaching characteristics. The irrigation scheduling test was again duplicated at the Safford Experiment Station and is presented in another report. Results from this years data indicate that there was no significant difference in yield between the 3 methods. Also, there was no significant difference in the amount of applied irrigation water. The AZSCHED and ERIE methods will be developed into Extension educational tools and released for use by growers.
6
Purbashree, Sarmah. "Mechanical and leaching characterization of inert waste landfills for safe and sustainable management". Kyoto University, 2020. http://hdl.handle.net/2433/259083.
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Yusoff, Wan Abdullah bin Wan. "Effect of zeolites on soil characteristics, leaching and surface pollutant losses form soils of contrasting textures". Thesis, Lancaster University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.531713.
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Hackett, A. J. "The influence of contaminated crushed brick aggregate on the strength, durability and leaching characteristics of concrete". Thesis, Queen's University Belfast, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273043.
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Schmidt, Martin. "Assessment of the physical, chemical and leaching characteristics of a marine sediment dredge spoil at Bing Bong, Northern Territory /". Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09AR/09ars353.pdf.
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Plappally, Anand Krishnan. "Theoretical and Empirical Modeling of Flow, Strength, Leaching and Micro-Structural Characteristics of V Shaped Porous Ceramic Water Filters". The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1276860054.
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Miyauchi, Teruhisa. "Development of a new analytical method for quantifying benzalkonium chloride in treated wood and evaluation of its leaching characteristics under different ambient conditions". Kyoto University, 2008. http://hdl.handle.net/2433/136698.
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Kyoto University (京都大学)0048
新制・論文博士
博士(農学)
乙第12215号
論農博第2673号
新制||農||959(附属図書館)
学位論文||H20||N4382(農学部図書室)
UT51-2008-C985
北海道大学大学院農学研究科林産学専攻
(主査)教授 今村 祐嗣, 教授 中野 隆人, 教授 梅澤 俊明
学位規則第4条第2項該当
12
Acharya, Lok P. "Chemical and Physical Characteristics of Mahoning River Sediment Before and After Fungal Bioremediation". Youngstown State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1211558693.
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Dunja, Rađenović. "Uticaj starenja stabilizovanog i solidifikovanog sedimenta na strukturne karakteristike matriksa i izluživanje metala". Phd thesis, Univerzitet u Novom Sadu, Prirodno-matematički fakultet u Novom Sadu, 2020. https://www.cris.uns.ac.rs/record.jsf?recordId=114883&source=NDLTD&language=en.
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Predmet izučavanja ove disertacije obuhvatio je ispitivanje uticaja starenja stabilizovanog/solidifikovanog (S/S) sedimenta zagađenog teškim metalima i arsenom, i efikasnost primenjenih imobilizacionih agenasa (Portland cement, kreč, leteći pepeo, zeolit, montmorilonit i kaolinit) nakon dugogodišnjeg starenja S/S smeša. Shodno tome ispitana je dugoročna stabilnost i postojanost dobijenih S/S smeša sa aspekta izluživanja pomenutih metala, promene u minerološkim i strukturnim karakteristikama, kao i uticaj sušenja i zrenja materijala na pomenute parametre. Istraživanja u disertaciji obuhvatila su dve faze. Prva faza imala je za cilj procenu rizika i početnu karakterizaciju netretiranog sedimenta primenom analize pseudo-ukupnog sadržaja metala kojom je utvrđen sadržaj metala u početnom uzorku sedimenta. Druga faza uključivala je primenu tretmana stabilizacije i solidifikacije na kontaminirani sediment dodavanjem različitih imobilizacionih agenasa. Analize su se vršile nakon 7 i 28 dana od primenjenog S/S tretmana, kao i nakon 7 godina sa ciljem da se utvrdi uticaj višegodišnjeg starenja i zrenja monolitnih smeša na mobilnost metala i strukturne karakteristike smeša. U okviru druge faze istraživanja ispitana je toksičnost S/S smeša primenom DIN i TCLP testova izluživanja, dok je test toksičnosti primenom bakterija Vibrio Fischeri doprineo u sagledavanju procene rizika S/S smeša po organizme. Nakon 28 dana i 7 godina korišćena je sekvencijalna ekstrakcija za određivanje mobilnost i biodostupnost metala u monolitnim matriksima. U cilju utvrđivanja mikrostukturnih karakteristika sedimenta primenjena je rendgenska difrakciona analiza (XRD) za ispitivanje kristalnih struktura S/S smeša i detekciju mineralnog sastava. Pomoću elektronskog mikroskopa i energodisperzivnog detektora sa X-zrakom (SEM/EDS) određena je kvalitativna i kvantitativna distribucija metala i drugih elemenata od interesa, dok se za identifikaciju formiranih funkcionalnih grupa u monolitnim smešama primenio spektrometar sa infracrvenom Furijeovom transformacijom (FTIR). Na osnovu dobijenih rezultata zaključeno je da se mobilnost teških metala i arsena značajno smanjila nakon 7 godina za smeše tretirane cementom (C5), krečom (L10), letećim pepelom (F30) i kaolinitom (K20), a efekat stabilizacije je pokazan transformacijom metala iz direktne toksične frakcije u stabilnije oblike. Smeše C5 i K20 ispoljavaju najmanje toksične efekate od svih smeša, jer je procenat inhibicije na bioluminiscentnim bakterijama manji od 13%, dok je u pogledu izdržljivosti monolitna smeša C5 pokazala najveću pritisnu čvrstoću od svih smeša. Dobijeni podaci su neprocenjivi za dobijanje stvarnog uvida u dugoročnu efikasnost primenjenog tretmana i mogućnost bezbedne upotrebe ili odlaganja dobijenih S/S smeša sa aspekta zaštite životne sredine, kao i ekonomski i ekološki prihvatljivog upravljanja opasnim otpadom.The subject of study in this dissertation included to investigate the effect of aging of stabilized/solidified (S/S) sediment contaminated with heavy metals and arsenic, and the efficacy of the applied immobilization agent (Portland cement, lime, fly ash, zeolite, montmorillonite and kaolinite) after long-term aging of S/S mixtures. Thelong - term stability and stability of the obtained S/S mixtures from the aspect of leaching of the mentioned metals, changes in mineralogical and structural characteristics, as well as the influence of drying and maturation of the material on the mentioned parameters were examined. The research in the dissertation included two phases. The first phase aimed at risk assessment and initial characterization of untreated sediment using pseudo-total metal content analysis which determined themetal content in the initial sediment sample. The second phase involved applying stabilization and solidification treatments to the contaminated sediment by adding various immobilizing agents. The analyzes were performed after 7 and 28 days from the applied S/S treatment, as well as after 7 years in order to determine the influence of perennial aging and maturation of monolithic mixtures on metal mobility and structural characteristics of the mixtures. In the second phase of the study, the toxicity of S/S mixtures using DIN and TCLP leaching tests was examined, while the toxicity test using bacteria Vibrio Fischeri contributed to the assessment of the risk of S/S mixtures to organisms. After 28 days and 7 years, sequential extraction was used to determine the mobility and bioavailability of metals in monolithic matrices. In order to determine the microstructural characteristics of the sediment, x-ray diffraction analysis (XRD) was used to examine the crystal structures of S/S mixtures and to detect the mineral composition. The qualitative and quantitative distribution of metals and other elements of interest was determined using an electron microscope and an energy-dispersive X-ray detector (SEM / EDS), while an infrared Fourier transform spectrometer(FTIR) was used to identify the formed functional groups in monolithic mixtures. Based on the obtained results, it was concluded that the mobility of heavy metals and arsenic decreased significantly after 7 years for mixtures treated with cement (C5), lime (L10), fly ash (F30) and kaolinite (K20), and the stabilization effect was shown by transformation of metals from direct toxic fractions into more stable forms. Mixtures C5 and K20 exhibit the least toxic effects of all mixtures, because the percentage of inhibition on bioluminescent bacteria is less than 13%, while in terms of durability, the monolithic mixture C5 showed the highest compressive strength of all mixtures. The obtained data are invaluable for gaining real insight into the long-term efficiency of the applied treatment and the possibility of safe use or disposal of the obtained S/S mixtures from the aspect of environmental protection, as well as economically and ecologically acceptable hazardous waste management.
14
Nelson, John D. "Toxicity characteristic leaching procedure analysis of dye containing sludges". Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-10062009-020242/.
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Vann, Kevin N. "Leaching behavior of personal computer central processing units (CPUs) using standardized and modified toxicity characteristic leaching procedure (TCLP) tests". [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0001149.
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16
Countess, Stephanie Jean. "Evaluating Leachability of Residual Solids from Hydraulic Fracturing in the Marcellus Shale". Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/56156.
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The process of natural gas extraction through hydraulic fracturing produces large quantities of fluid containing naturally-occurring salt, radionuclides, and heavy metals which form residual solids during storage and treatment. The purpose of this research was to characterize the residual solids from hydraulic fracturing operations in the Marcellus Shale to predict the leaching behavior of select elements in disposal environments.
Samples collected for this research were: (1) drilling mud, (2) treated sludge from the chemical treatment of process waters, (3) solids from the gravity settling of produced water, and (4) sludge solidified prior to disposal in a municipal landfill. These samples were subjected to various digestion techniques to determine the composition and leaching potential for elements of concern. Strong acid digestions were performed to determine the total environmentally available composition, whereas weak acid digestions were used to predict the leaching potential of these solids under various environmental conditions. The extraction fluids for the leaching experiments included weak acetic acid, acid rain, reagent water, and synthetic landfill leachate. Solids were agitated in a standard tumbling apparatus to simulate worst-case conditions based on ASTM and EPA recommendations. Results from EPA's Toxicity Characteristic Leaching Procedure (TCLP) were used to determine if solids were considered hazardous based on the metal leaching potential.
The results from strong and weak acid digestions were compared to better understand the types and quantity of materials that have the potential to leach from the samples. This research may be used to develop best management practices for hydraulic fracturing residual solids.Master of Science
17
Chestnutt, Sheryl A. "Comparison of the extraction procedure toxicity test (EP) and the toxicity characteristic leaching procedure (TCLP) for the analysis of trace organic compounds in land applied municipal wastewater sludges". Thesis, Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/44626.
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The current Environmental Protection Agency (EPA) method utilized for analysis of trace organic chemicals and heavy metals leached from solid waste is the Extraction Procedure (EP) Toxicity Test. Because of various operational problems and limitations of the EP, the EPA has developed and plans to implement the Toxicity Characteristic Leaching Procedure (TCLP), which is an expanded version of the EP capable of analyzing more organic components, in particular volatile organic chemicals.
The purpose of this research was to investigate and compare the ability of the EP and TCLP test procedures to quantitatively recover added surrogate standards (1,2-dibromoethane, bromoform, 1â chlorooctane, fusarex, heptachlor, and DDT) and also qualitatively identify and evaluate unknown trace organic chemicals in domestic wastewater sludges. In order to meet the research objectives established, three small (approximately 1 MGD or less) municipal wastewater treatment plants that land applied their sludges were analyzed.
Master of Science
18
Swann, Christina Talbot. "Evaluating the Leachability of Elements from Residuals Generated by Hydraulic Fracturing in Marcellus Shale". Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/73707.
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The purpose of this research was to characterize the residual solids produced from hydraulic fracturing operations in the Marcellus Shale region. Four field samples were evaluated: drilling mud, treated sludge from the chemical treatment of process water, solids from the gravity settling of produced water, and sludge solidified prior to disposal in a municipal landfill. Cement kiln dust (CKD), used for solidification, was also considered in this study. All samples were subjected to a variety of laboratory techniques to determine their elemental composition and the potential for the elements to leach from the landfill. Strong acid digestion using a 3:1 combination of nitric acid to hydrochloric acid in a microwave with closed vessels was used to determine overall elemental composition. Leaching experiments were performed with de-ionized water and acetic acid (0.57%, pH 2.88) in an attempt to respectively evaluate the effects of weak and strong fluids that might be encountered by the residuals in landfill environments. Elements were analyzed by means of ICP-MS revealing the increased tendency for alkali metals, alkaline earth metals and halogens to leach. Leachablility was further increased for metals when exposed to acidic conditions.Master of Science
19
Alderman, Lori A. "The evaluation and comparison of the extraction procedure toxicity test and the toxicity characteristic leaching procedure for the analysis of municipal wastewater sludges". Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/44103.
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A viable sludge management alternative is land application of waste sludge. However, it is necessary to implement efficient monitoring and analysis of land applied sludges in order to assess potential health risks associated with this means of disposal.
The State of Virginia is considering a proposal that requires land-applied wastewater sludges to undergo analysis by EPAâ s Toxicity Characteristic Leaching Procedure (TCLP) (EPA, 1986b) to determine if the sludge exhibits hazardous characteristics, which preclude land application as a management alternative. The method currently used for the analysis of hazardous wastes is the Extraction Procedure (EP) Toxicity Test. Both of these test methods analyze for trace organic chemicals and heavy metals. However, the TCLP is designed to analyze for volatile organic chemicals to a greater extent than the EP. Because of the added complexity and the current expense of the TCLP, the State is concerned that the TCLP may not be warranted for the analysis of trace organic chemicals in land-applied sludges.
This research was designed to compare the abilities of the EP and TCLP for the analysis of trace organic chemicals in wastewater sludges. Samples from three municipal wastewater treatment plants that utilize secondary biological treatment, aerobic digestion and land-apply waste sludge were evaluated by both EP and TCLP methods. Both tests utilize a weak acid extraction to remove organic chemicals from the wastewater sample. The weak acid extract was subjected to liquid-liquid extraction (EPA Method 625) to partition and concentrate the organic chemicals into methylene chloride; this methylene chloride extract was then subjected to GC and GC/MS for quantitative analysis and qualitative identification of targeted and nontargeted organic chemicals.
In order to assess recovery and extractability efficiencies of each test, surrogate standards were added prior to the test procedure. These standards were bromoform, 1-chlorooctane, DDT, ethylene dibromide (EDB, a volatile fungicide), fusarex (tetrachloronitrobenzene), and heptachlor. Control samples were run for both EP and TCLP, in addition to a sludge samples with no surrogates added.
Analysis indicated that both the TCLP and EP tests showed high variability for the recovery of the sludge surrogates. The recoveries of the surrogate standards were low and varied between zero and 30 percent depending on the standard and the matrix. Surrogate recoveries were evaluated with respect to various physical/ chemical properties of the individual standard, the sample site, and the test method utilized. Although the TCLP recovered the volatile surrogate standards only slightly better than the EP, there was no statistically significant difference between the TCLP and EP for the recovery of the non- and semi-volatile surrogate standards.
Specific trace organic chemicals identified in the sludges included dimethylpentanol, dichlorodimethoxybenzene, 4-methylphenol, and tetrabutylphenol. Other chemicals, such as contaminants and artifacts resulting from laboratory processing and background contamination in the reagents, were also identified in the blank control samples as well as the sludge samples.
Master of Science
20
Mallik, Gayadhar. "Leaching characteristics of fluoride from pond ash". Thesis, 2011. http://ethesis.nitrkl.ac.in/2485/1/Leaching_characteristics_of_fluoride_from_pond_ash.pdf.
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Now, more than 100 million tons of coal fly ash is produced annually in India from combustion of coal in power plants. It is expected that about 150 million tons of coal ash will be produced due to burning of coal in power plants by the year of 2015. This will require about 30,000 hectare of land for the disposal of ash. One of the biggest problems due to disposal of large quantities of coal ash is the possible leaching of different hazardous pollutants, including fluoride. A thorough investigating concerning leaching of fluoride from fly ash is much more indispensable to know the impingement of fluoride due to its leaching from fly ash to ground water as well as surface water. In this paper, short term and long term leaching studies will be carried out on pond ash, pond ash water of different thermal power plants: Rourkela Steel Plant (RSP), Rourkela; National Thermal Power Corporation (NTPC), Kaniha; National Aluminium Corporation Limited (NALCO), Angul; IB Thermal Power Station (ITPS), Banharpali. The amount of fluoride released in different experiments will be evaluated. Environmental impact of pond ash and fluoride has been discussed.
21
Chen, Sin-yu, i 陳信彧. "Leaching Characteristics of Heavy Metals and Dioxins from Fly Ash Using Batch and Dynamic Leaching Procedures". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/49125581222596611089.
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碩士國立中央大學
環境工程研究所
100
The MSWI fly ash which contains high concentrations of heavy metals and dioxins has been classified as hazardous waste. In this study, batch and dynamic leaching procedures were used to explore the leaching behaviors of heavy metals and dioxins in the fly ash generated from MSWI. Heavy metals and dioxins leached from different solutions are assessed, and different chelating agents are tested for higher stability of MSWI fly ash. The results of batch leaching procedure indicate that the leached Pb concentrations of the plant A were 21.6, 19.3, 16.7 and 16.0 mg/L for HAc, acid rain, humic acid and SDBS as solvents, respectively. These concentrations all exceeded the regulated standard (5 mg/L). The leached Pb, Cu and Cd concentrations of the plant B exceeded the regulated limit, but only occurred in HAc solution. Highly chlorinated PCDD/Fs were observed in the leachates of fly ash, accounting for more than 80% of PCDD/Fs. In addtion, 3,3’,4,4’-TCB, 2,3’,4,4’,5-PeCB and 2,3,3’,4,4’-PeCB were also observed in the leachates of the fly ash. The results of dynamic leaching procedure indicated that the leached Pb concentrations of the plant A was the highest, followed by Zn, Cu, and Cr, whereas Cd was the lowest. In the SDBS solution, the leached Cd concentrations was the highest. On the other hand, the leached Zn, Pb, Cu and Cr concentrations were the highest in HAc solution. The structures of fly ash were destroyrd due to the long-term washing (13 days) of fly ash were washed by HAc solution, resulting in the increase of PCDD/Fs concentrations leached from the fly ash. 3,3’,4,4’,5-PeCB, 2,3,3’,4,4’,5-HxCB and 2,3,3’,4,4’,5,5’-HpCB were also observed in the leachates of the fly ash, compared with the results of batch leaching. Adding inorganic sulfide (A plant) or phosphate (B plant) along with cement results in the best stabilization effect in treating the fly ash. We also found there was some stabilization effect for dioxins of fly ash.
22
Liu, Chien-Chung, i 劉建中. "Leaching Characteristics of Sewage Sludge Disposed in Seashore landfill". Thesis, 1995. http://ndltd.ncl.edu.tw/handle/87829832461365521137.
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Chan, Yung-Hisang, i 詹詠翔. "Leaching characteristics of BOF slag affected by various aging conditions". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/28628046429431027252.
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碩士國立成功大學
環境工程學系碩博士班
97
Based on previous studies, calcium-based ashes and slags have the potential to absorb CO2. In this study, the degree of aging of natural aged and rapid carbonation BOF slag were compared on their physical and chemical characteristics, including the conversion rate of total calcium, pH, ANC/BNC, and pH dependence behavior leaching test. Results show that the BOF slag with calcium content over 20% has the potential to absorb CO2. The calcium conversion rate of 6 months natural aged BOF slag were about 15%. Rapid carbonation of BOF slag at temperature of 100℃, moisture content of 90% and 10% partial pressure of carbon dioxide under the reaction for 24 hours, the conversion rate of BOF slag is up to 18%. According to the follow-up grinding analysis and SEM analysis, it was discovered that BOF slag carbonation reaction occurred on the surface with calcium oxide as the main reaction species. And BOF slag was confirmed by the leaching test which the surface layer of calcium carbonate reduces the effects of dissolution. In addition, the BOF slag conversion degree of 8 hours carbonation has similar results with that of 6 months natural aged. The rapid carbonation BOF slag although lower pH values from 12.5 to about 11, but did not increase the leaching of heavy metals concentration. BOF slag after a 24-hour rapid carbonation absorbs the amount of CO2 up to 0.035g of CO2/g of BOF Slag. This shows rapid carbonation has the ability of CO2 absorption at the same time achieved the goal of BOF slag stabilization, which enhances the value of BOF slag follow-up reuse.
24
Van, der Merwe Ryno. "Leaching characteristics of copper refractory ore : effect of pre-oxidation stage". Thesis, 2010. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000303.
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M. Tech. Metallurgical Engineering.A novel process of leaching copper refractory ore from Nchanga mine, Zambia, in two stages consisting of a pre-oxidation step and an acid dissolution stage was investigated by means of a leach test rig.
25
LEE, CHIA-YING, i 李佳穎. "Solutions of Leaching and Expansion Characteristics of Electric Arc Furnace Slags". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/sdn3r6.
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碩士中臺科技大學
環境與安全衛生工程系碩士班
106
In recent years, the steel industry plays an important role in social and economic life，In the domestic steel industry, the output of steel products also grows year by year with the vigorous development. The by-product of the steelmaking scrap smelting process is electric arc furnace slag , Which can be subdivided into ballast and ballast according to differences in the process stages. The main components of both are calcium, silicon, iron magnesium and the like, which has the potential of replacing natural gravel as an engineering material. However, -MgO and f-CaO, as the application of engineering materials, there is the risk of health instability and expansion. Therefore, in this study, the target of reducing ballast and ballast in electric arc furnace was explored, and their differences in physico-chemical properties were discussed. The toxicity of TCLP and MTCLP combined with EU environmental dissolution / extraction test (CEN / TS 14429 pH correlation test and CEN / TS 14405 column dissolution test) were used to test the dissolution of arc furnace ballast. The dissolution characteristics of heavy metals and their compatibility with the environment were also discussed. And then to hot pressing expansion method and the rapid mortar bar method to determine the visibility of the arc furnace slag and alkali activation program to provide a high chemical energy to increase the reactivity of the arc furnace ballast to overcome the problem of structural instability and explore the activation of alkali Improvement of the feasibility of using arc furnace slag as engineering material. It can be concluded from the experimental results that for the different ballast and ballast, due to different process conditions, the material properties are different. The elemental composition of the ballast and ballast are Ca, Mg and Fe as the main components, while the ballast calcium-removing compound In addition, another iron oxide and other iron compounds. However, the ballast and ballast were in compliance with the TCLP test. According to the pH correlation test, the acid equivalent of the ballast required to reach a specific pH value is higher than that of the oxidized slag, and has a higher buffering capacity and a more gradual pH change. However, the dissolution rate of heavy metals in different pH conditions indicates that the dissolution of most heavy metals is directly below the detection limit. However, using the column dissolution test results to calculate the hundred-year release rates of heavy metals, it can be seen that the dissolution characteristics of arc furnace slag can be in line with the Netherlands Building Materials Decree (BMD) specification. However, it is known from the thermogravimetric heat flow curve and the crystal phase composition of the healthy test that the thermal and heavy losses of the raw material ballast and the reduced ballast can be found that the ballast and the ballast are both calcined with Ca (OH) 2 and Mg (OH) 2 Magnesium compounds mainly from the hot expansion and rapid mortar bars also showed the reduction of ballast and ballast as Bo Zuolan materials application of cement hydration program with the problem of health instability and from the use of alkali with high alkalinity alkali Activation of ballast and reducing ballast to improve f-CaO, f-MgO reactivity found alkali equivalent base modulus than 4% 1.25,6% 1.75 is better for the current more suitable to improve the arc furnace ballast expansion with the match ratio. The results show that, both the activity index and alkali activated index of AAS+DS mortar are more than 75%, that means AAS+DS mortar is available to be the cementitious material. In the results of engineering and environmental properties, AAS+DS mortar with hydration products mainly composed with calcium silicate hydrate and calcium aluminum silicate hydrate. Thfore, compressive strength of AAS+DS mortar are higher than OPC mortar. Besides, better thermal resistance performance represent in AAS+DS mortar with calcium silicate hydrate. Through 550°C heat treatment, AAS+DS mortar still keep more than 98% residual strength. From result of tank test, AAS+DS mortar shows lower Ca dissolution and the all regulated heavy metal leaching levels are not detected. In summary, both compressive strength and heat treatment and tank test, AAS+DS mortar is better than OPC mortar to be the engineering material.
26
Tlotleng, Nonhlanhla. "Evaluation of atomic force microscopy techniques for imaging and studying surface characteristics of bacterial systems involved in bioleaching". Thesis, 2009. http://hdl.handle.net/10210/2457.
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M.TechAtomic force microscopy (AFM) has been an integral tool in bacterial studies for resolving surface structures. Novel applications of this instrument in research require the development of sample preparation techniques and improvement of existing ones. Careful selection of the scanning parameters is particularly crucial when exploring the full potential of the AFM. The objective of this study was to design sample preparation methods for AFM imaging bioleaching bacteria and optimise the scanning parameters (deflection setpoint, feedback loop and the scan rate) for contact mode (CM) imaging in air. The method should be simple, fast and cost effective. The strategy used in this study of (i) evaluation of support substrates for bacterial attachment, (ii) investigation of the effect of pH and centrifugation on cell samples during imaging. Centrifuged and noncentrifuged cell samples suspended in either deionised water (pH 7) or acidified water (pH 1.5) were tested for imaging. Mica and glass cover slips were used as potential substrates for attachment. Cells were attached to substrates for imaging by simple adsorption (‘air-drying’ method). To optimise the scanning parameters, the effect of different values of the scan rate, deflection setpoint and the feedback gains on the quality of AFM imaging was investigated. Optimisation of these parameters was found to be instrumental when imaging weakly adsorbed samples prepared by simple adsorption and ‘soft’ samples such as bacterial cells. The results obtained from these experiments were used during preparation of iron- oxidising leaching bacteria for AFM imaging. The surface morphology of iron-grown bacterial samples was investigated with contact mode AFM in air. Reproducible results obtained in each scan shown by the stability of morphological characteristics of bacterial samples indicate that (i) mica can be used successfully as a substrate for attaching cells, (ii) centrifuged bacterial samples can be easily imaged (iii) scanning with scan rate values of <0.5Hz, deflection setpoint of between 0.2-0.5V and feedback values of < 5.000V improve the image quality and can prevent deformation of the bacterial cells by the tip. Non-centrifuged samples could not be imaged, indicating that bacterial cells need to be separated from growth residues as a prerequisite for successful AFM imaging.
27
Ko, Ming-Sheng, i 柯明賢. "Leaching Mechanisms and Stabilizing Characteristics of Copper Xanthate and Copper Dithiocarbamate Complexes". Thesis, 2000. http://ndltd.ncl.edu.tw/handle/08580844943615152387.
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博士國立成功大學
環境工程學系
88
ABSTRACT Although cement-based solidification/stabilization (S/S) technique has been advanced to treat hazardous metal-bearing wastes, many researcheres more recently studying on the long-term stability of the solidified matrix bearing hazardous heavy metal are of the opinion that metal solidified in cementitious matrix will indicate a lack of stabilizing characteristics owing to long exposure in an acidic environment. Thio-surfactants such as xanthates and dithiocarbamates are commonly used for flotation and precipitation of metals as frothers and collectors and have been applied in the industrial wastewaters for the removal of metals by forming highly insoluble metal xanthate and dithiocarbamate complexes. Some of the past studies indicate that xanthates and dithiocarbamates have the strong metal-binding properties and could strongly stabilize metal ion under acidic condition and room temperature. It is still further expected that the xanthates and dithiocarbamates will directly be used as the stabilizing agent to treat the hazardous heavy metal. However, it is still a mystery whether some significant amounts of metal ions can be leached out of insoluble metal xanthate and dithiocarbamate complexes through the various pH (acid, neutral and alkaline) of renewable synthetic extraction fluids at the different temperatures and understanding of such leaching mechanisms can be useful for evaluating the long-term stability of the insoluble metal complexes under the relevant environment situations. Thus, the purpose of the present work was mainly to provide detailed information of the leaching mechanism and stabilizing characteristic of the synthetic copper ethyl xanthate (Cu-EtX) and copper diethyl dithiocarbamate (Cu-DDTC) complexes through the semi-dynamic leaching test (SDLT) using 1 N acetic acid (pH 2.08), 0.2 N NaHCO3 (pH 8.0) and 1 N NaOH (pH 14) extraction fluids at two different temperatures (25℃ and 60℃) to simulate the relevant environment situations. The thio-surfactants xanthate, potassium ethyl xanthate (C2H5OCS2K, abbreviated as KEtX), and dithiocarbamate, sodium diethyl dithiocarbamate (C5H10NSNa, abbreviated as NDDTC) were used as a model stabilization agents to stabilize the copper ion, which became the insoluble copper ethyl xanthate complex (Cu-EtX) and copper diethyl dithiocarbamate complex (Cu-DDTC). The leached species of the leachant (liquid phase) were characterized by using SDLT and ultraviolet-visible spectrophotometer (UV-visible) techniques to obtain the leaching mechanism of Cu-EtX and Cu-DDTC complexes under three different pH extraction fluids at two different temperatures. The crystallinity, functional group and morphology of the unleached and leached Cu-EtX and Cu-DDTC complexes (solid phase) were examined by using X-ray diffractometer (XRD), fourier-transform infrared spectrophotometer (FTIR) and scanning electron microscopy/energy- dispersive X-ray analysis (SEM/EDAX) techniques to identify the stabilizing characteristic of the Cu-EtX and Cu-DDTC complexes. Based on the results of SDLT and UV-visible analyses of synthetic Cu-EtX and Cu-DDTC complexes through three different pH extraction fluids at two different temperatures, the leaching mechanisms are summarized as followed: (1) Cu-EtX complex Regardless of pH of extraction fluid and temperature of environment, the Cu-EtX complex is mostly the presence of Cu(EtX) and (EtX)2, the Cu(EtX) is the controlling factor for the dissolution of copper ion and EtX-. The (EtX)2 will constantly dissolve and leach out of the insoluble Cu-EtX complex, but the (EtX)2 still further decomposes into EtX- under 0.2 N NaHCO3 (pH 8.0) and 1 N NaOH (pH 14) extraction fluids. Then, the EtX- will decompose into EtOH and CS2 under 1 N acetic acid (pH 2.08) and 1 N NaOH (pH 14) extraction fluids. (2) Cu-DDTC complex Regardless of pH of extraction fluid and temperature of environment, the Cu-DDTC complex is mostly the presence of Cu(DDTC)2, the Cu(DDTC)2 is the controlling factor for the dissolution of copper ion and DDTC-. Then, the DDTC- will decompose into secondary amine (R2NH) and CS2 under 1 N NaOH (pH 14) extraction fluid. Based on the results of XRD, FTIR and SEM/EDAX analyses of unleached and leached Cu-EtX and Cu-DDTC complexes, the long-term stabilizing characteristics of the insoluble Cu-EtX and Cu-DDTC complexes existed in three different pH extraction fluids at two different temperatures are summarized as followed: (1) Cu-EtX complex The raise of temperature and pH will cause the microstructural change to the leached Cu-EtX complex. The main stabilization phases existed in Cu-EtX complex leached through 1 N acetic acid (pH 2.08) and 0.2 N NaHCO3 (pH 8.0) extraction fluids at 25℃ both are Cu(EtX) and the main stabilization phases existed in Cu-EtX complex leached through 1 N NaOH (pH 14) extraction fluid at 25℃ are copper organosulfur compound and non-stoichiometric copper sulfide. The main stabilization phases of Cu-EtX complex leached through 1 N acetic acid and 0.2 N NaHCO3 extraction fluids at 60℃ are copper organosulfur compound and non-stoichiometric copper sulfide and the main stabilization phases of Cu-EtX complex leached through 1 N NaOH extraction fluid at 60℃ is copper organosulfur compound, non-stoichiometric copper sulfide and the reprecipitate of copper hydroxide. (2) Cu-DDTC complex The raise of pH will cause the microstructural change to the leached Cu-DDTC complex. Regardless of temperature of environment, the main stabilization phases existed in Cu-DDTC complex leached through 1 N acetic acid (pH 2.08) and 0.2 N NaHCO3 (pH 8.0) extraction fluids both are Cu(DDTC)2 and the main stabilization phases existed in Cu-DDTC complex leached through 1 N NaOH (pH 14) extraction fluid are Cu(DDTC)2 and the reprecipitate of copper hydroxide.
28
Rapulane, Mary. "Leaching characteristics of PGM tailings at elevated temperatures and pressure in Chloride media". Thesis, 2008. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000290.
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Thesis (MTech. degree in Chemical Engineering)--Tshwane University of Technology, 2008.Studies the leaching characteristics of the flotation tailings at different temperatures and pressure in chloride media using an autoclave.Subsequently, to assess and compare the leachability under atmospheric and oxidation pressure leaching conditions. The parameters employed to study atmospheric and oxidative pressure leaching were as follows: Sodium chloride concentration, oxygen partial pressure, % feed solids and particle size distribution.HNO3 acid concentration was kept constant in most of the leach tests. The development of a mathematical reaction rate model that describes the leaching kinetics. The rate values are subsequently used to model the leaching reaction.
29
Hsu, Kuei-Chiu, i 許桂秋. "Leaching Characteristics of Heavy Metals and Dioxin from Different Fly Ashes Using Sequential Extraction Procedure". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/05404369541609736203.
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碩士國立中央大學
環境工程研究所碩士在職專班
96
The fly ashes generated from incineration and metallurgical processes have been classified as a hazardous waste. In this study, sequential extraction procedure, TCLP and aqua regia extraction were used to explore chemical bondings and heavy metals in fly ashes generated from different steel industries and municipal waste incinerators (MWI). The potential impact of heavy metals leached in different leaching processes on the environment was investigated. In addition, the effect of acidic agents on total TEQ of dioxin in the collected ash samples was investigated by analysis of PCDD/F contents in residues collected from each fraction of sequential extraction. The results indicate that different chemical bondings and leaching characteristics of collected ash samples were observed and relied on steel-making materials, types of steel industries, types of steel-making furnaces, and operating parameters. Cadmium was mainly leached out from the first three steps (water-soluble, ion-exchangeable, and hydroxides and carbonates fractions) (Plant A: 93.6%, Plant B: 43.1%, Plant C: 70.8%, Plant D: 66.5%) and should be noticed during treatment due to its high mobility. The bonding structure of leached lead was performed differently based on the basic characteristics of ash samples. The results of heavy metals obtained from TCLP showed that the leached cadmium concentrations of collected ashes were 41.0, 6.84 and 23.7 mg/L, respectively, for Plant A, B, and C. These concentrations all exceeded the regulated standard. The leached lead concentrations for Plants A, B, C, and D were, respectively, 165, 83.2, 7.92, 9.83 mg/L, which were all over the regulated standard as well. The distributions of 17 toxic PCDD/Fs extracted from residue using sequential extraction procedure were found no difference in first five different extraction fractions (water-soluble, ion-exchangeable, hydroxides and carbonates, amorphous Fe-Mn oxides and crystal Fe oxides), and their concentrations were all below the regulated standard (1.0 ng I-TEQ/g). The highest concentrations of dioxin in the residue were found at the 6th extraction step（sulfide fraction）and this demonstrated the sufficient ability to leach a large amount of PCDD/Fs by using strong oxidants and acids at the sulfide fraction.
30
周順裕. "Influence of Silicate and Phosphate Additives on Leaching Characteristics of Stabilized Municipal Incinerator Fly Ashes". Thesis, 1997. http://ndltd.ncl.edu.tw/handle/52111936303249123044.
Pełny tekst źródła
31
GARG, SAKSHI. "STUDY OF LEACHING CHARACTERISTICS OF STAINLESS STEEL PICKLING SLUDGE & ITS UTILIZATION WITH CONCRETE USING TAGUCHI METHODOLOGY". Thesis, 2016. http://dspace.dtu.ac.in:8080/jspui/handle/repository/15341.
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Steel finishing operations such as pickling, galvanizing, plating, etc., involve a process of removing scale, rust and dust from the surface of stainless steel. In this, sheets of steel are immersed in hot acidic solution resulting in waste liquor which contains heavy metals like Fe, Cr, Ni, etc. When treated with lime, these heavy metals get settled as metal hydroxides in form of sludge. As per the Act of Hazardous Waste (Management and Handling) Rules, 1989, the disposal of lime treated spent pickling sludge should be done with consideration and is not easy. In normal practice, this sludge is being stored in leak proof bags and no proper disposal technique is being employed by small and medium industries.
An attempt has therefore been made to utilize the lime treated pickling sludge in cement concrete mix in the presence of fly-ash as a binder agent. The main objective is to immobilize heavy metals in the concrete matrix and studying its leaching characteristics and compressive strength. Sludge is characterized for the heavy metal content using AAS, EDX and XRD. Other physical and chemical properties are also analysed. Test cubes of nominal mix M20 were prepared and these were tested for its 7 and 28 days compressive strength. Toxicity characteristics leaching procedure (TCLP) test as per USEPA was carried out on these cubes to study the extent of immobilization and stabilization of heavy metals in the concrete matrix.
For this, Four factors were varied on three levels i.e. Percentage of cement replaced by sludge (5%, 7.5% & 10%) and Percentage of fly-ash (0%, 15% & 20%), type of cement used and particle size grading of sludge, to assess the effect of these factors on compressive strength and heavy metal concentrations in leachate. Taguchi methodology (L9 orthogonal array) was used for optimizing the design of experiments and for further analysis.
Experimental results show that the lime treated pickling sludge can be utilized with cement/concrete with some binding materials like fly-ash. By Analysis of Mean (ANOM) method, it was found that 7.5% addition of sludge and 20% fly-ash as partial replacement of cement with 43 grade OPC and sludge particle size ranging between 0.3 to 2.36mm produced the optimal performance for compressive strength and heavy metal immobilization values of the cement-sludge-flyash concrete cubes. By Analysis of Variance (ANOVA) method, it was found that particle size grading of sludge and percent of sludge added as cement replacement contributed 46% and 41% respectively to the optimal performance. Formation of C2H, C3H and gypsum (C-S-H gel) may be contributing in the better performance of concrete.
32
Chen, Zhao-yu, i 陳昭羽. "Effects on leaching characteristics of heavy metals in municipal solid waste incinerator residues by accelerated carbonation". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/72738852564174089829.
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碩士逢甲大學
環境工程與科學所
99
This research investigated that the accelerated carbonation reaction effects on leaching characteristics of heavy metals and stabilization of municipal solid waste incineration (MSWI) bottom ash and fly ash (referred to as ash). The experiments were conducted by controlling 25 weight percentage of moisture content of ash, carbon dioxide concentration (10% and 20%) and fly ash addition ratio (10%, 20% and 30%), respectively. This research was also established the kinetics parameters of accelerated carbonation reaction using Thermogravimetric analysis (TGA) method, and evaluated the carbon reduction and/or carbon dioxide capture efficiency by MSWI ash during accelerated carbonation reaction process. The experimental results showed that higher CO2 concentration will help to accelerate the carbonate reaction, and to reduce the required time for MSWI ash stabilization. Meanwhile, the higher MSWI fly ash addition ratio will enhance the carbonate reaction rate and ash stabilization degree, due to its good moisture holding capacity. Besides, the calcium carbonate (CaCO3) formed in ash was more that the ash stabilization will be better. According to results of leaching concentration of tested heavy metals of ashes by accelerated carbonation, the tested heavy metals, such as zinc (Zn), cadmium (Cd) and lead (Pb), their leaching concentration decreased with carbonate reaction time increased. However, the copper (Cu) leaching concentration increased from 0.42±0.02 mg/l to 1.12±0.06 mg/l with an increase the carbonation time. According to results of MINTEQA2 model for prediction of heavy metals speciation formed in ash, the Cu speciation will be Cu2OCl2 (Melanothallite) that it will reduce the saturation index (SI: -19.361) and increase the solubility of ash. Therefore, the Cu leaching concentration will increase after accelerated carbonation reaction. In summary, the toxicity characteristics leaching procedure (TCLP) concentration of tested metals in accelerated carbonation ash were all in compliance with the current Taiwan’s regulation thresholds. All tested hazardous MSWI ashes have converted to non-hazardous ashes by accelerated carbonation process that will promote the potential application in further resourcification and reutilization of ash. According to analysis results of carbonate reaction kinetic, the slow carbonation reaction occurred at controlling of high CO2 concentration and smaller particle size of ash. This is due to the smaller particle size of ash has a low relatively porosity. When higher CO2 concentration will be enhanced the carbonation reaction rate and then formed calcium carbonate crystals on the ash surface. It could clog the ash pores and inhibit the diffusion of CO2. According to the analysis results of activation energy, the smaller particle size of ashes (ranged between 0.074 mm and 0.149 mm) has a lower activation energy (ranged between 17 kJ/mole and 76 kJ/mole). However, when the particle size increased to 0.149-0.420 mm, its activation energy will be increased approximately between 62 kJ/mole and 159 kJ/mole. According to the relationships between pH and carbon dioxide variation, the stabilization index (ΣΔpH/ΣΔCO2/Ca) for evaluating accelerated carbonation reaction was established. The results of stabilization index of accelerated carbonation ash were approximately between 1.2 and 2.6. Based on the results of accumulated amounts of CO2 uptake by MSWI ash, in the case of 10% CO2 concentration, every 100 grams of MSWI ash could capture the amounts of CO2 were approximately ranged between 43 grams and 45 grams during the accelerated carbonation. The overall effectiveness of carbon dioxide capture and reduction was also estimated approximately between 310 thousands and 370 thousands every year in Taiwan if all MSWI ash treated by accelerated carbonation process. In summary, the results of this study can provide further information for selection of potential technology in resourcification and reutilization of accelerated carbonation ash, but will also evaluate the benefits of carbon dioxide capture and reduction by accelerated carbonation process.
33
Craig, Deborah Carol. "Pressure leaching characteristics of a magnetically enhanced concentrate with specific refrence to the precious metal components". Thesis, 2008. http://hdl.handle.net/10539/4922.
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ABSTRACT
The overall metallurgical processing of precious group metals (PGM) contained in
mined ores involves a number of hydrometallurgical operations for the removal of
base metals and sulphidic sulphur before the final refining of individual PGM’s to
saleable metal. The final process in this sequence is a batch pressure leach in which
further base metals are removed prior to the introduction into the Precious Metals
Refinery (PMR). Significant amounts of PGM losses are however experienced in this
stage, which is called the tertiary leach. This is attributed to difficulties in monitoring
and controlling the leach within a tight range of parameters. The losses are highly
undesirable, as the precious metal rich stream then requires additional process steps
to recover the values, which negatively impacts on the pipeline time. This
investigation will focus of the tertiary leach.
The exact reasons, chemical mechanisms and driving force which influence the
dissolution of precious metals is not fully known and understood. However, since the
plant often experiences significant PGM dissolution, it is critical to understand and
establish a knowledge base to provide a more scientific methodology for improving
the control of this process.
The objectives of this study are defined as :
1. The identification of conditions under which significant PGM dissolution is
observed.
2. Establishing the order in which the precious metals solubilise.
3. Determining the cause of PGM solubilisation.
4. Illustrating the parameters required to monitor and control the end point to
consistently maximise base metal removal and minimise PGM losses to leach
liquors.
It is experimentally observed that the most affected PGMs during the tertiary leach
are rhodium, ruthenium and palladium. All are observed in different amounts in the
leach liquors when the reduction-oxidation potentials exceed 600 mV.
The most important finding of this study is that the soluble PGMs originate from a
phase that is termed Pd type 1 mineral which is a fine grained phase that is already
present in the leaching circuit in the feed material presented to the tertiary pressureleach. This phase appears to be produced in the primary pressure leach. It is
postulated that it arises due to the presence of base metal sulphides that are
entrained with the magnetic fraction of the material. During the primary pressure
leach, these base metal sulphides appear to form fine grained material that result in
the formation of the Pd type 1 phase seen in the tertiary leach. If the amount of
entrained base metal sulphides in the magnetically enhanced concentrate (MEC) is
reduced or removed completely, it will remove the source of the soluble PGMs and
consequently PGM losses to the leach liquor will only occur in the event of severe
and extreme over-leaching.
The first prize for controlling the end point of this leach is to consistently maximise
base metal leaching while minimising PGM losses. The end point of the leaching
process is currently determined by monitoring the redox potentials of the slurry
samples taken at various intervals. A problem with this approach is that the redox
determined under atmospheric pressure conditions differs from the values in the
pressure vessel. Another drawback is that in the redox range of 550 mV to 650 mV,
the potentials are extremely sensitive and huge increases are experienced over small
time intervals. This makes it very difficult to predict the exact end point consistently
for different batches. A better approach would be to identify alternative parameters
that would allow ample time to make an informed decision regarding the end point.
This appears to be possible by monitoring the copper and nickel in solution. When
the concentration of these two base metals increases substantially, this would signal
the start of the termination sequence and cooling down of the reactor. The increase
for copper appears to be from ~19-39 g/l and nickel from ~6.5-8.5 g/l for the ore
tested in this study.
34
Chen, Ying-chung, i 陳盈中. "Binding species and leaching characteristics of copper ions adsorbed onto the surface of coal-burn fly ash". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/90427872197764136726.
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碩士嘉南藥理科技大學
環境工程與科學系碩士班
92
The coal-burn fly ash used in this study was collected from coal-burn power plants of Taiwan Power Company. Part of fly ash samples were decarbonized in a oven (550 ℃) to investigate the effect of minerals composition, specific surface area, and pH of the fly ash on the adsorption of copper ions from the aqueous solution . The binding species and leaching characteristics of copper ions adsorbed onto the surface of coal-burn fly ash were also discussion in the present work. Research results based on adsorption experiments demonstrate that when solution pH was not controlled, most of aqueous copper ions were removed. The final solution pH was larger then 5.6 when the adsorption reaction finished. Removal of copper ions was attributed to chemical deposition and adsorption. The removal efficiency of copper ions by fly ashes were more than 90 %, with some cases 100%. Based on the results of adsorption isotherm experiments, the average specific adsorption capacity of copper ions was in the range of 2.35~3.83 mg- Cu2+/g-fly ash. Furthermore the major binding species of copper ions adsorbed onto the surface of coal-burn fly ash are carbonate bound and Fe-Mn oxides bound. After adsorption reaction, fly ashes with CaO and MgO content larger than 20% passed through toxicity characteristic leaching procedure, which means concentration of copper ions leaching from copper-leaden fly ash less than 15 mg/L limitation. In addition, research result also shows that when solution pH was controlled at 5.0, the removal of copper ions was in the range of 46.3~57.2 %, with an average specific adsorption capacity of copper ions in the range of 1.45~1.96 mg- Cu2+/g-fly ash. The removal of copper ions was positively related to BET, Fe2O3, and CaO. Most of the binding species of copper ions adsorbed onto the surfaces of A~I coal-burn fly ashes was carbonate bound. The binding species of copper ions adsorbed onto the surfaces of J~O coal-burn fly ashes was residual. The copper-leached fly ash of A~O must be treated with 0.1N HNO3 for 24 hour to pass through the limitation of TCLP in Taiwan.
35
Yu-ChuanSu i 蘇鈺荃. "Heavy metal leaching characteristics of electric arc furnace slags and its feasibility on reusing in graded aggregates". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/66395916816392479568.
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36
Liao, Yi-Pao, i 廖義博. "Effects of Zero Valent Iron on the Leaching Characteristics of Nitrate and Soluble Chloride in the Municipal Sludge". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/02836608066067847958.
Pełny tekst źródłaStreszczenie:
碩士嘉南藥理科技大學
環境工程與科學系暨研究所
94
The aim of this study is to examine the effect of zero-valent iron on the co-compost of zero-valent iron and sewage sludge. The leachability of nitrate and soluble chloride in sewage sludge was observed during the composting period. Samples of sewage sludge were gathered from the An-Pin sewage treatment plan in Tainan City. The experimental parameters were designed as follows: Fe0/sludge mass ration :0-30g/kg, water content of compost: 80%, sampling time of compost: 0, 5, 10, 20 and 30 day.The sewage sludge was firstly completely mixed with Fe0 for 18 mins and the packed into plastic columns with a 9.5 cm inner diameter and 35 cm hight. To discuss the effect of acid precipitation on the sludge co-compost, acidified water with pH = 4.0 was prepared by spiking H2SO4 into D.I. water. The water content, elemental conpsition, C/N, nitrate, nitrite, amino-nitrogen, soluble chloride and ferrious ion in the sewage samples were determined. The leachate from the column were collected in a beaker and used for the analysis of NO3--N, NO2--N, NH3-N and soluble chloride. Based on the results of experiments, it was found that zero-valent iron appeare to have no effect on the reduction of NO3- in the sewage sludge. On the other hand, Fe0 was found to reduce the soluble chloride in the sludge singnificantly.
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Kuo, Chin, i 郭覲. "Selective Leaching Properties of Cu-Al-Ni Shape Memory Alloys and Damping Characteristics of Ni-Mn-Sn Ferromagnetic Shape Memory Alloys". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/tt88at.
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碩士國立宜蘭大學
化學工程與材料工程學系碩士班
106
The first part of this study is to investigate the selective leaching properties of Cu-XAl-4Ni (X=12.5、13.0 and 13.5) shape memory alloys (SMAs). According to the XRD, DSC, and SEM results, the Cu-XAl-4Ni SMAs were in the (18R) martensite phase at room temperature. The electrochemical result reveals that there were no obviously different from each other in the corrosion resistance of the Cu-XAl-4Ni SMAs in Ringer’s solution. The ICP-MS result indicates that the Ni ions after Cu-XAl-4Ni SMAs immersion in Ringer’s solution for 90 days were higher than Cu and Al ions. The low concentrations of Cu and Al ions stem from the oxidation of Cu and Al atoms near the surface of the Cu-XAl-4Ni SMAs to form Cu2O and Al2O3 films, but there were no NiO film formed on the surface of the Cu-XAl-4Ni SMAs. The selective leaching properties of the Cu-XAl-4Ni SMAs were inferior to that of the TiNi SMA but were much better than those of the TiNiCu and TiNiFe SMAs. Cu-XAl-4Ni SMAs are potential candidates to serve as biomaterials owing to their lower cost, better workability, and more easily obtainable desirable martensitic transformation temperatures by adjustment of the chemical composition of the alloys. In the second part of this study, we investigate the damping capacities of the inherent and intrinsic internal frictions (IFPT+IFI) of Ni50Mn40-xSn10+x (x = 0、0.5、1、2、3 and 4) ferromagnetic shape memory alloys (FSMAs). According to the DMA result, the damping capacities of the (IFPT+IFI)L21→14M peaks of the Ni50Mn40Sn10 and Ni50Mn39.5Sn10.5 FSMA are higher than those of the other Ni50Mn40-xSn10+x FSMAs, which exhibit (IFPT+IFI)L21→14M(dominant)+10M(partial), (IFPT+IFI)L21→10(dominant)+14M(partial), or (IFPT+IFI)L21→4O peaks, as there are more abundant movable twins dissipating energy during damping in the 14M martensite than in the 10M or 4O martensite. The Ni50Mn38Sn12 FSMA exhibits a lower (IFPT+IFI)L21→10(dominant)+14M(partial) peak than the (IFPT+IFI)L21→4O peak of the Ni50Mn37Sn13 and Ni50Mn36Sn14 FSMAs as there is a smaller number of movable twins in the 10M martensite than in the 4O martensite. Compared with other SMAs, the Ni50Mn40-xSn10+x FSMAs with the 14M martensite structure not only exhibit a high damping at a temperature above 100°C, but also possess the advantages of unique magnetic properties, low cost, and simple control of the desired martensitic-transformation temperature by adjusting the chemical composition of the alloy.
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Huang, Ching-Yun, i 黃靖云. "Effects of different curing processes on the leaching characteristics of heavy metals in the bottom ash from the municipal solid waste incinerator". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/56217679708935461164.
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碩士嘉南藥理科技大學
環境工程與科學系碩士班
96
To reduce the environmental impact during the utilization and disposal of bottom ash from municipal solid waste incinerator (MSWI), the leachability of the heavy metals in the ash should be taken into consideration. In the present work, different curing processes have been used for stabilization of heavy metals in bottom ashes. To understand the effects of different curing processes on the leaching characteristics of heavy metals in the bottom ash from MSWI, bottom ash with particle size less than 4.75 mm diameter was stabilized by natural and accelerated aging. In natural aging process, the bottom ash was posed in the ambient air condition. In accelerated aging processes, ashes were soaked in tape water and saturated lime solution. Toxicity characteristic leaching procedure (TCLP), EPA SW-846 Method 1320 (Multiple Toxicity Characteristic Leaching Procedure, MTCLP), column test (CEN/TS 14405), water-soluble chloride content (CNS 13407) and sequential extraction procedure (SEP) were used to evaluate the leaching characteristics of heavy metal and chloride ion in the aged bottom ashes. It was found that leaching of heavy metals in naturally aged bottom ash was not reduced with increasing curing time. However, leaching of heavy metals in accelerated aging bottom ash declined with increasing curing time. In addition, based on the TCLP, MTCLP and column test results of aged ashes through natural aging and accelerated aging processes, it was found that the heavy metals leachability can meet the requirement of TCLP standards in Taiwan, but results based on column test elucidates the bottom ash had some problems in the long-term stability. The accumulation leachability of Cu and Pb can’t meet the requirement of building materials decree (BMD) standards of Netherlands. According to the SEP analysis, mainly bounded patterns of the heavy metals in the aged ashes through natural aging and accelerated aging processes are Fe-Mn oxides bound, organic matter bound and residual bound.
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Jyun-Sian, Liou, i 劉俊賢. "Studies on selective leaching properties of TiNiFe shape memory alloys and surface characteristics of the 316L stainless steel modified by ethylene vinyl acetate powder/chitosan composite films". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/46151782634170561122.
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碩士國立宜蘭大學
化學工程與材料工程學系碩士班
104
The first part of this study is to investigate the selective leaching and surface characteristics of Ti50Ni50-xFex(x = 1, 2, and 3) shape memory alloys using inductively coupled plasma mass spectrometry, X-ray diffractometry, electrochemical tests, and X-ray photoelectron spectroscopy. In our results, the concentrations of Ni and Fe ions selectively leached from each specimen were considerably higher than that of Ti ions. Electrochemical tests revealed a gradual deterioration in the corrosion resistance of Ti50Ni50-xFex SMAs as the Fe content in the alloys was increased. X-ray photoelectron spectroscopy results indicate that the surface of each specimen is primarily made up of passive TiO2 films. NiO and Fe2O3 oxides, which also formed on the surface of Ti50Ni50-xFex SMAs, deteriorated the uniformity and undermined the protective effect of TiO2 films, resulting in the highly selective leaching of Ni and Fe ions. Ti50Ni50-xFex SMAs possess a number of favorable properties than other SMAs; however, high concentrations of selectively leached Ni and Fe ions may pose a risk in biomedical applications, particular used in implant materials. The second part of this study is to investigate the surface characteristics and anticoagulant properties of 316L stainless steel coated with ethylene vinyl acetate powder (EVA)/chitosan (CS) composite films, using various EVA powder/CS rations, for biomedical applications. The Fourier transform infared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) results showed that in the EVA powder/CS composite films, the signals of the –CH3 and –Si-O-Si hydrophobic functional groups became more significant when the EVA powder content increased, resulting in a higher water contact angle. The results of the bicinchoninic acid (BCA) protein assay showed that EVA powder/CS composite films with EVA powder/CS content ratios lower than 5 possessed lower adsorption concentrations of bovine serum albumin than chitosan films, suggesting that the anticoagulant properties of the EVA powder/CS composite films deteriorated significantly because its surface morphology became rougher with abundant protuberances. Therefore, EVA powder/CS compsite films with appropriate EVA powder/CS content ratios are good candidate materials for biomedical applications because they possess advantages such as hydrophobic properties, smooth surface morphologies, and a low capacity for protein adsorption.
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Wen-Lin, Shung, i 商文麟. "The analysis of toxicity characteristic leaching procedure( TCLP) extractionof chlorinated hospital waste sludge". Thesis, 1993. http://ndltd.ncl.edu.tw/handle/86029433625026928158.
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Weng, Hsu-Po, i 翁序伯. "Leaching Treatment of Metal Contaminated Farm Soil and Investigating the Characteristic Change of the Soil". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/85000410936006863012.
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Xie, Fu-Zong, i 謝宗甫. "Dynamic Characteristic of Reduction of Lead Metal Leaching from Flyash of Incineration by Microwave Digestion". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/6agv73.
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碩士國立臺北科技大學
環境規劃與管理研究所
95
In general TCLP concentrations of Lead and Cadmium in flyash are usually over the regulation standards. It results in many restrictions on treatment and recycling. Flyash emitted from a large-scale refuse incinerator in the north Taiwan was investigated in this study. The objective of this research is discuss the dynamic of TCLP reduction, lead metal in flyash by Microwave Digestion Treatment method. Samples of flyash were divided into four groups, dp>417µm、295µm< dp<417、74µm< dp<295µm及37µm< dp<74µm. The experiments follow-up on the conductions, 600W, digested liquid 9M, liquid-solid ratio 1/10 and on the different digestion time and temperature to find out the rate of TCLP reduction. Result reveal after MDT ,the rate of TCLP reduction in lead metal up to more than 90％ at digestion temperature 160℃ and digestion time 16 minutes. On the other hand, the diameter of particle affect the TCLP reduction in lead metal more seriously. Useing the linear regression to published the relationship between digestion time and rate constant of digestion in every group of diameter of particle, it was found that the appearance activation energy of every group of flyash （dp>417µm、295µm< dp<417、74µm< dp<295µm及37µm< dp<74µm）is 7.6(Kcal/mole)、11.9(Kcal/mole) 、20.2(Kcal/mole) and 32.6(Kcal/mole). The experimental results indicate that the diameter of particle is an important factor on the TCLP reduction rate in lead metal. When the flyash diameter of particle became smaller, the diffusion between acid molecule and particle of flyash will be limited because of the outer layer and inner part layer drag of flyash particles . Therefore the rate of microwave digestion treatment and TCLP reduction in lead metal would be reduced.
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"Chartopolis - A Self Driving Car Test Bed". Universidad Peruana de Ciencias Aplicadas (UPC), 2018. http://hdl.handle.net/10757/624055.
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