Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1914. / The entire thesis text is included in file. Typescript. Illustrated by authors. Title from title screen of thesis/dissertation PDF file (viewed April 9, 2009)

Thesis (M.S.)--University of Nevada, Reno, 2007. / "December, 2007." Includes bibliographical references (leaves 166-176). Online version available on the World Wide Web.

Thesis (doctoral)--University of Tartu, 1998. / Includes bibliographical references.

Thesis (M. Eng.)(Metallurgical)--University of Pretoria, 2005. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.

The potential for mobilization of SO4 and Cl from coal stockpiles and coal processing waste and refuse (waste rock) disposal areas to the receiving streams and groundwater is an environmental concern and proper management practices are necessary to minimize the impact of these discharges. In an effort to characterize the long-term environmental impact of weathering in from both a typical coal stockpile and coal waste disposal areas a series of laboratory- scale and field-scale kinetic tests were performed with the ultimate goal of improving both coal and coal waste management at coal mines in a manner that minimizes the discharge of sulfate (SO4) and chloride (Cl). Laboratory experiments demonstrated that kinetic testing is a productive method for understanding the chemistry of surface water discharges from coal stock piles. However, these tests proved to be problematic in simulating the weathering of coal refuse. In an effort to improve the kinetic tests, field test columns were constructed that eliminated this deficiency. Unfortunately, field-scale test columns were found to be difficult to construct and, due to extremes weather events, difficult to maintain for an adequate test period. In the course of the experiment elemental and mineralogical data were collected both before and after weathering of fresh, run-of-mine coal from the Springfield (No.5) coal seam and coal refuse samples from processing the Springfield (No. 5) and Herrin (No. 6) coal seams. Duplicate columns were constructed in 2008 to conduct kinetic testing of the fresh run-of-mine No. 5 coal collected at an active underground mine in Southeastern Illinois. These columns measured 15.4 cm (6-inch) diameter by 61 cm (2-ft.) tall and were leached in batch mode for 32 months (27 leach cycles) using locally-collected rainfall water at a rate consistent with climatic data. Similarly, triplicate columns were constructed in 2009 to conduct kinetic testing of fine and coarse coal collected at the cooperative mine. The coal refuse test columns also measured 15.4 cm (6-inch) diameter by 61 cm (2-ft.) tall and were leached in batch mode for 41 months (31 leach cycles). Coal refuse was emplaced into the columns using a measured amount of compaction and a controlled moisture content (15.3%) based on data from previous laboratory engineering tests (Proctor testing). Locally-collected rainfall water was again used for leaching at a rate consistent with climatic data. Three columns investigated the leaching of compacted coarse refuse (the control) and three columns investigated the leaching of compacted 80:20 blend of coarse and fine refuse. To verify the results of the laboratory-scale, kinetic tests on coal refuse six field-scale (208 L or 55 gal.) columns were constructed in 2011 which measured 57.2 cm (22.5-in.) diameter by 85.1 cm (33.5-in.) tall and were leached in batch mode for 18 months (17 leach cycles). Two columns were again investigated the leaching of compacted coarse refuse (the control), while two additional columns leached compacted 85:15 blend of fine and coarse refuse and two columns tested a 80:10:10 blend of coarse refuse, fine refuse, and ground limestone. These field-scale tests allowed the use of full-sized refuse particles and were subject to natural precipitation events. An improved geochemical data set was obtained by these experiments due to an extension of the laboratory kinetic tests from 12 to 32 months to better simulate a mine-site stockpile conditions. Similarly, kinetic tests on coal refuse were extended from 12 to 41 months to better simulate SO4 and Cl release from a coal refuse facility. Three coal refuse disposal options were investigated in these experiments: 1) compacted coarse refuse (the control), 2) a compacted blend of fine and coarse refuse and 3) a compacted blend of coarse refuse, fine refuse, and ground limestone. Trends observed during the course of this research in leachate chemistry, as well as, comparisons of refuse placement options provide important insights necessary for development of management practices which minimize SO4 and Cl in coal mine discharge. The observed temporal changes were largely due to the presence of carbonate and aluminum mineral buffering of pH; three stages were observed during the kinetic testing of the Springfield (No.5) coal (Stages 1 through 3). Conversely, only Stage 1 and Stage 2 were observed in leaching tests of coal refuse due to the greater amount of compaction, which reduced the hydraulic conductivity and slowed the weathering rate. The identification of these three stages is important because of the improvement in coal and coal refuse management and water quality treatment realized by an understanding of these geochemical trends. The stages observed in the coal column leachate are: Stage 1: Laboratory coal column leachate collected during the first 7 months of simulated weathering of the No.5 coal maintained a favorable pH (> 6.4) maintained by an excess in bicarbonate alkalinity which minimized discharge of SO4 and common coal mine drainage metal Fe. The concentrations of Na and Cl in the leachate were elevated in early leach cycles, but declined rapidly as water soluble salts were flushed from the coal columns, which was an indicator that a portion of the Cl was water soluble forms such as salts and dissolved Cl- ions in pore water and not bound to the organic structure. Stage 2: A transitional period (Stage 2) occurred during the next 3 months of simulated coal stockpile weathering (7 to 10 months). This stage marked the exhaustion of the carbonate mineral buffer and an acceleration of coal weathering. Stage 2 leachate was characterized by a rapid decrease in the leachate pH to 4.0 and an increase in concentration of SO4 and dissolved Fe. Both Na and Cl in the leachate continued to decline in Stage 2, but the release related to flushing rate and not pH. Stage 3: After 10 months of simulated coal stockpile weathering, the leachate pH continued to slowly decrease to values below 2.0. At the same time the SO4 concentration increased rapidly and Fe concentration increased by over a factor of ten. The decline in pH was believed to have been restricted by iron and possibly aluminum mineral buffering during Stage 3. The release of Na and Cl in the coal increased somewhat during Stage 3 presumably due to slaking of shale contain in the ROM coal and the subsequent increase in the exposure of the soluble portion of the Cl to weathering and flushing. Laboratory leach testing of the Springfield (No.5) Coal from Southeastern Illinois suggests that: (1) SO4 levels in coal stockpile discharge would be relatively low up to ≈7 months. This time period, therefore, should correspond to the operational limit of run-of-mine (ROM) coal storage for this case example; and (2) Elevated discharges Cl- and the Na+ counter ion occurs immediately and may require control by operational measures (dilution and/or periodic blow down from a closed loop water handling system) to minimize Cl. A favorable leachate pH of > 6.4 which typified Stage 1 was also maintained throughout the laboratory-scale experiments for all blended coal refuse and in two of three columns simulating coarse coal refuse. Lower pH conditions similar to Stage 2 in the coal study was observed in leachate from only one of three coarse refuse columns after ≈12 months of kinetic testing. In all laboratory column experiments, the concentrations of Na and Cl in the leachate were elevated in early leach cycles, but declined rapidly as water soluble salts were flushed from the coal refuse columns. However, in the field column experiments favorable pH conditions (> 6.4) were only maintained throughout the 18 month experiment in the two columns which received a relatively high amount or ground limestone addition (10%). Lower pH conditions similar to Stage 2 observed in the coal leachate tests were observed in leachate from two coarse refuse columns and one of two blended refuse columns after ≈12 months. Complementary laboratory and field kinetic testing of coal refuse also suggest that: 1) SO4 levels in simulated coal refuse disposal area can be minimized by systematic compaction and co-disposal of properly dewatered fine and coarse refuse, and 2) elevated Cl (and Na) discharges occur immediately, which may require operational measures such as dilution and/or periodic blow down from the mine’s closed loop system. In most cases all of these measures can be completed using existing facilities at minimal additional costs. This dissertation provides insights into the potential for long-term discharge of SO4 and Cl from coal processing facilities in the Southeastern part of the Illinois and the operational controls that should be considered to minimize these impacts. Additional studies are suggested to confirm the findings with different coal seams and mining regions in the Illinois basin. Some notable findings include: 1) An increased understanding of coal and coal refuse leachate geochemistry can be expected by extending kinetic testing from the normal short-term tests (<12 >months) to longer-term testing (32-41 months). By conducting long-term (>12 months) kinetic tests additional observations were possible regarding limitations on rate of release of Cl and SO4 by both carbonate mineral buffer (pH 6.4) and an mineral ferrihydrite buffer at pH ≈3.4, as well as, increases due to chemical and physical weathering (slaking) of the materials. An understanding of the bicarbonate buffer is necessary to design operational controls during mining and reclamation and to evaluate the impact of alkaline (i.e. limestone) additions. 2) Kinetic testing of coal refuse should simulate real-world placement of these materials in a disposal area. Current coal mining practices require both the placement and compaction of coarse or blended refuse, which is not duplicated in kinetic methods employed by previous investigators that conducted tests using relatively loose-packed materials. Kinetic testing of non-compacted coal refuse is inconsistent with mine safety regulations in the U.S. dictate that compaction will be required for the structural stability of the coal refuse facility. Therefore, this experiment improved on the conventional kinetic testing methodology and provides a more appropriate estimate of the weathering rates as they relate to the release of SO4 and Cl from these materials. However, due the low hydraulic conductivity of the compacted refuse blends the laboratory column leachate volumes were inadequate to conduct key alkalinity analyses when rainfall was applied at physically realistic rates. Larger volume field columns may, therefore, serve as a better alternative. 3) Limitations on the mobility of the powerful oxidant, ferric iron (Fe3+), created by compaction and the presence of alkaline materials that support the presence of a bicarbonate buffer are critical in controlling the release of SO4. 4) Increased compaction in the two coal refuse blends would be expected to restrict the hydraulic conductivity and, therefore, flushing rate of the refuse and, as a result, reduce the corresponding release of Cl. However, the reverse was observed which was due in part to the high release rate of the soluble portion of the Cl from fine-grained materials, which in this case was the <200 mesh>(<0.074mm) fine coal processing waste. Moderate additions (<5%) of fine-grained (< 1 cm) limestone provides both an increased stability of blended coal refuse due to its role as a drying and cementing agent. The environmental benefit of limestone addition to coal refuse blends is the reduction of SO4 release due to: 1) Lower infiltration of H2O and O2(g) as the result of improved compaction, and 2) Increase in the net neutralization potential which results in increased bicarbonate mineral buffering. However, it is recognized that due to the size of these facilities limestone additions at the rate suggested by this research would be costly.

Cette thèse adapte le modèle GRAAL, initialement dédié à la prédiction du comportement à long terme des verres nucléaires type R7T7, à l’étude de l’altération des verres basaltiques, matériaux considérés comme des analogues naturels des verres nucléaires. Cette thèse cherche à valider les hypothèses fondatrices du modèle GRAAL et évaluer sa robustesse en l’appliquant aux verres basaltiques. Pour ce faire, deux axes de recherche sont suivis. Le premier consiste à reparamétrer le modèle GRAAL pour le verre basaltique. Le travail de description de la couche amorphe qui se forme durant l’altération du verre, a été entrepris aux moyen d’expériences de lixiviation de verres basaltiques simplifiés à 90°C et différents pH (7 ; 8,5 et 10). Des fortes analogies observées sur le comportement des éléments ont permis de conserver une partie du paramétrage du modèle GRAAL dédié aux verres nucléaires. Des expériences ont également été conduites pour affiner la compréhension des mécanismes d’altération à long terme du verre basaltique. A fort progrès de réaction, l’altération du verre basaltique n’est pas limitée par un mécanisme diffusif, comme c’est le cas pour le verre nucléaire, mais par une très lente hydrolyse du réseau vitreux entretenue par la précipitation de phases secondaires. Ainsi une modification de la loi cinétique de dissolution du verre a été réalisée.Le modèle, reparamétré avec la même méthodologie que celle employée pour le paramétrer pour le modèle de verre nucléaire parvient à rendre compte avec justesse de l’altération du verre basaltique pour les pH faiblement basiques, renforçant ainsi la confiance que l’on peut accorder au modèle sur les prédictions liées au verre nucléaire. / This thesis adapts the GRAAL model, initially dedicated to the prediction of the long-term behavior of nuclear glasses, to basaltic glasses.This thesis intends to validate the relevance of the founding hypotheses of the GRAAL model as well as to assess its robustness. To achieve this, two lines of research were carried out simultaneously. The first was to re-parameterize the GRAAL model for basaltic glass compositions. To describe the amorphous layer formed during glass alteration, simple basaltic glasses were leached at 90 ° C and various pH (7, 8.5 and 10). Strong analogies observed on the behavior of the elements allowed to preserve a part of the parameterization of the GRAAL model. Experiments have also been conducted to improve the understanding of the mechanisms of basaltic glasses alteration in silica saturated conditions. It is shown that alteration of the basaltic glass is not limited by a diffusive mechanism like nuclear glass, but by a very slow hydrolysis of the vitreous network sustained by the precipitation of secondary phases. Thus, a modification of the kinetic law of the model controlling the dissolution of the glass was carried out.The model, then, accurately accounts for the alteration of basaltic glass in slightly alkaline conditions, thus reinforcing the confidence that can be given to the model on the predictions related to nuclear glasses.

Made available in DSpace on 2014-06-11T19:23:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-07-05Bitstream added on 2014-06-13T18:09:18Z : No. of bitstreams: 1 garcia_ig_me_araiq_parcial.pdf: 206327 bytes, checksum: 96ce2244d53cd6b26eef086e6ea1ab1a (MD5) Bitstreams deleted on 2015-06-03T11:42:41Z: garcia_ig_me_araiq_parcial.pdf,. Added 1 bitstream(s) on 2015-06-03T11:44:08Z : No. of bitstreams: 1 000721776_20150831.pdf: 196800 bytes, checksum: 7855db2c08df6a688c6d404aeebac5cd (MD5) Bitstreams deleted on 2015-08-31T12:12:22Z: 000721776_20150831.pdf,. Added 1 bitstream(s) on 2015-08-31T12:12:57Z : No. of bitstreams: 1 000721776.pdf: 1205657 bytes, checksum: 64d61f0337043ba4804b2dcd6c5ffe5b (MD5) / Na natureza, os sulfetos minerais constituem a principal fonte para extração industrial de metais, como o cobre, o chumbo, o zinco e o níquel. A calcopirita (CuFeS2) é um sulfeto de cobre importante, sendo o mineral de cobre mais abundante na natureza. Dentre os processos utilizados para a extração de metais está a biolixiviação, que consiste no processamento de minérios utilizando-se micro-organismos, e é reconhecida hoje como uma metodologia interessante sob os pontos de vista econômico e ambiental. Neste contexto, este trabalho foi desenvolvido com o objetivo de se obter consórcios oxidantes de ferro e de enxofre capazes de promover a solubilização da calcopirita. Para obtenção dos consórcios, quinze amostras minerais fornecidas pela Companhia Vale S.A. foram enriquecidas em meios de cultivo específicos. Foram obtidos 4 consórcios oxidantes de ferro e 4 oxidantes de enxofre, denominados Dep SOS-4, S3A, SO3, D1. A análise dessas amostras minerais por difração de raios X evidenciou a presença predominante de quartzo (SiO2) nas amostras Dep SOS-4 e S3A e nas amostras D1 e SO3 também foi observado covelita (CuS), pirrotita (FeS), calcopirita (CuFeS2) e enxofre (S0). Os consórcios oxidantes de ferro foram adaptados ao crescimento em calcopirita e submetidos a ensaios de biolixiviação em calcopirita. Agrupamentos dos consórcios também foram realizados, porém sem adaptação prévia à calcopirita. Nos ensaios de biolixiviação, os valores de Eh se elevaram continuamente nos frascos inoculados, estabilizando ao redor de 550 mV, indicando o aumento da relação Fe3+/Fe2+, o que afeta diretamente a solubilização dos metais pela ação oxidante do Fe3+. Mesmo considerando que a calcopirita é um dos sulfetos mais refratários ao ataque oxidante, bacteriano ou químico, a extração de cobre nos ensaios... / In nature, sulphide minerals are the main sources for extraction of some metals for industrial uses, such as copper, lead, zinc and nickel. One of the most important and explored copper sulphide is chalcopyrite, being the most abundant copper mineral in nature. Metals can be extracted using microorganisms, leading the bioleaching to an economic and environmentally sustainable process. In this research, it was developed different iron and sulfur oxidizer consortium to promote chalcopyrite (CuFeS2) solubilization. All consortium were obtained from previous enrichment in a specific culture of 15 ore samples provided by Companhia Vale S.A. Four iron oxidizer and four sulfur oxidizer consortium were prepared, and named Dep SOS-4, S3A, SO3 and D1. X ray diffraction of the Dep SOS-4 and S3A samples showed mainly quartz content (SiO2), whereas the SO3 and D1 samples showed covellite (CuS), pyrrothite (FeS), chalcopyrite (CuFeS2) and sulfur (S0) presence too. The iron oxidizer consortium were adapted to grow with chalcopyrite and then used in shake flasks experiments with chalcopyrite. A mix of consortiums was performed, but without a previous adaptation to the chalcopyrite. The Eh values increased during the bioleaching of the inoculated flasks, stabilizing around 550 mV, which affects metal solubilization due to an increase in the Fe+3/Fe+2 ratio. The iron oxidizer consortium resulted in a better dissolution of the chalcopyrite when compare with the control, sulfur oxidizer consortium and pure strain At. thiooxidans - FG01. However, it was not observed any significant difference between the consortium and At. ferrooxidans - LR in the chalcopyrite dissolution. In the respirometric tests with chalcopyrite as substrate were observed lower consumption of oxygen to the iron oxidizer consortium (Dep SOS -4, S3A, SO3 and D1) in relation to... (Complete abstract click electronic access below)

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Orientador: Denise Bevilaqua / Banca: Ana Teresa Lombardi / Banca: Monica Cristina Teixeira / Resumo: Na natureza, os sulfetos minerais constituem a principal fonte para extração industrial de metais, como o cobre, o chumbo, o zinco e o níquel. A calcopirita (CuFeS2) é um sulfeto de cobre importante, sendo o mineral de cobre mais abundante na natureza. Dentre os processos utilizados para a extração de metais está a biolixiviação, que consiste no processamento de minérios utilizando-se micro-organismos, e é reconhecida hoje como uma metodologia interessante sob os pontos de vista econômico e ambiental. Neste contexto, este trabalho foi desenvolvido com o objetivo de se obter consórcios oxidantes de ferro e de enxofre capazes de promover a solubilização da calcopirita. Para obtenção dos consórcios, quinze amostras minerais fornecidas pela Companhia Vale S.A. foram enriquecidas em meios de cultivo específicos. Foram obtidos 4 consórcios oxidantes de ferro e 4 oxidantes de enxofre, denominados Dep SOS-4, S3A, SO3, D1. A análise dessas amostras minerais por difração de raios X evidenciou a presença predominante de quartzo (SiO2) nas amostras Dep SOS-4 e S3A e nas amostras D1 e SO3 também foi observado covelita (CuS), pirrotita (FeS), calcopirita (CuFeS2) e enxofre (S0). Os consórcios oxidantes de ferro foram adaptados ao crescimento em calcopirita e submetidos a ensaios de biolixiviação em calcopirita. Agrupamentos dos consórcios também foram realizados, porém sem adaptação prévia à calcopirita. Nos ensaios de biolixiviação, os valores de Eh se elevaram continuamente nos frascos inoculados, estabilizando ao redor de 550 mV, indicando o aumento da relação Fe3+/Fe2+, o que afeta diretamente a solubilização dos metais pela ação oxidante do Fe3+. Mesmo considerando que a calcopirita é um dos sulfetos mais refratários ao ataque oxidante, bacteriano ou químico, a extração de cobre nos ensaios... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In nature, sulphide minerals are the main sources for extraction of some metals for industrial uses, such as copper, lead, zinc and nickel. One of the most important and explored copper sulphide is chalcopyrite, being the most abundant copper mineral in nature. Metals can be extracted using microorganisms, leading the bioleaching to an economic and environmentally sustainable process. In this research, it was developed different iron and sulfur oxidizer consortium to promote chalcopyrite (CuFeS2) solubilization. All consortium were obtained from previous enrichment in a specific culture of 15 ore samples provided by Companhia Vale S.A. Four iron oxidizer and four sulfur oxidizer consortium were prepared, and named Dep SOS-4, S3A, SO3 and D1. X ray diffraction of the Dep SOS-4 and S3A samples showed mainly quartz content (SiO2), whereas the SO3 and D1 samples showed covellite (CuS), pyrrothite (FeS), chalcopyrite (CuFeS2) and sulfur (S0) presence too. The iron oxidizer consortium were adapted to grow with chalcopyrite and then used in shake flasks experiments with chalcopyrite. A mix of consortiums was performed, but without a previous adaptation to the chalcopyrite. The Eh values increased during the bioleaching of the inoculated flasks, stabilizing around 550 mV, which affects metal solubilization due to an increase in the Fe+3/Fe+2 ratio. The iron oxidizer consortium resulted in a better dissolution of the chalcopyrite when compare with the control, sulfur oxidizer consortium and pure strain At. thiooxidans - FG01. However, it was not observed any significant difference between the consortium and At. ferrooxidans - LR in the chalcopyrite dissolution. In the respirometric tests with chalcopyrite as substrate were observed lower consumption of oxygen to the iron oxidizer consortium (Dep SOS -4, S3A, SO3 and D1) in relation to... (Complete abstract click electronic access below) / Mestre

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