Thesis (Ph.D.) - University of Queensland, 2003. / Includes bibliography.

Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1947. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed July 9, 2010) Includes bibliographical references (p. 48).

Thesis (Ph.D.)--University of Missouri-Columbia, 2004. / Typescript. Vita. Includes bibliographical references (leaves 169-173). Also available on the Internet.

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Includes bibliographical references (p. 246-266).

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains vii, 63 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 52-53).

National Science Foundation (RANN) under Grant no.SIA 73-07871 A02

>Magister Scientiae - MSc / Energy production from coal comes with an environmental cost because of the toxic waste produced during coal combustion such as coal ash and brine which are potential water and soil pollutants. Coal ash and brine contain toxic elements which can leach and contaminate soils and ground water if not properly disposed. This study investigated the mobility of species in coal fly ash co-disposed with brine at Sasol Secunda power station in order to establish if the ash dam could act as a salt sink. The ash was dumped as a slurry with 5:1 brine/ash ratio and the dam was in operation for 20 years. It was hypothesized that the disposed Secunda fly ash was capable of leaching toxic metal elements into the surrounding soils and ground water and therefore could not be used as a long term sustainable salt sink. Weathered fly ash samples were collected along a 51 m depth core at the Secunda ash dam by drilling and sampling the ash at 1.5 m depth intervals. A fresh fly ash sample was collected from the hoppers in the ash collection system at the power station. Characterization of both Secunda fresh ash and Secunda weathered ash core samples was done using X-ray diffraction (XRD) for mineralogy, X-ray fluorescence (XRF) for chemical composition and scanning electron microscopy (SEM) for morphology. Analysis of extracted pore water and moisture content determination of Secunda fresh ash and Secunda weathered ash core samples was done in order to evaluate the physico-chemical properties of the fly ash. The chemical partitioning and mobility of metal species in the ash dam was evaluated using the sequential extraction procedure. The XRD spectra revealed quartz, mullite and calcite as the dominant mineral phases in the weathered Secunda ash core samples while Secunda fresh ash contained quartz, mullite and lime. The major oxides identified by XRF analysis for both Secunda fresh ash and Secunda weathered ash include: SiO₂, Al₂O₃, CaO, Fe₂O₃, MgO, Na₂O, TiO₂ and K₂O. The minor oxides identified for both Secunda fresh ash and Secunda weathered ash were P₂O₅, SO₃ and MnO. The trace elements identified for both Secunda fresh ash and Secunda weathered ash were As, Ba, Ce, Co, Nb, Ni, Pb, Rb, Sr, V, Y, Zr and Th. However, U was detected in some of the Secunda weathered ash samples but not in Secunda fresh ash. Both Secunda fresh ash and Secunda weathered ash was classified as class F based on the sum of the oxides of silicon, aluminium and iron by mass and the CaO content as reported by XRF analysis, and further classified as sialic and ferrocalsialic type highlighting the significant levels of Si, Al, Ca and Fe in the fly ash based on XRF analysis. The XRF analysis further showed that brine codisposal on the ash may have been responsible for the slight enrichment of some species such as Na, SO₄²⁻, Mg, K and V in the disposed Secunda weathered fly ash. However, there was no significant accumulation of these species in the disposed fly ash despite continuous addition of an estimated 117.65 billion litres of brine over the 20 year period that the dam existed. Furthermore, Secunda ash dam showed an overall total salt capture capacity of only -0.01 weight %, a strong indication that the ash dam was incapable of holding salts and would release elements to the environment over time. The scanning electron microscopy (SEM) analysis revealed spherical particles with smooth outer surfaces for Secunda fresh ash while Secunda ash core samples consisted of agglomerated, irregular particles appearing to be encrusted, etched and corroded showing that weathering and leaching had occurred in the ash dam. A decrease in pH, electrical conductivity (EC) and total dissolved solids (TDS) was observed in Secunda ash core samples compared to Secunda fresh ash. While Secunda fresh ash (n = 3) had a pH of 12.38 ± 0.15, EC value of 4.98 ± 0.03 mS/cm and TDS value of 2.68 ± 0.03 g/L, the pH of Secunda ash core (n = 35) was 10.04 ± 0.50, the EC value was 1.08 ± 0.14 mS/cm and the TDS value was 0.64 ± 0.08 g/L. The lower pH in the ash dam created an environment conducive to the release of species through leaching, while the lower EC and TDS in the ash dam implied the loss of ionic species from the ash which resulted from leaching. The moisture content (MC) analysis indicated that Secunda ash dam was very damp with an average MC of 54.2 ± 12.66 % for Secunda ash core creating favourable conditions for leaching of species in the ash dam while Secunda fresh ash had MC of 1.8 ± 0.11 %. The bottom of Secunda ash dam appeared water logged which could cause slumping of the dam. The sequential extraction procedure revealed that the major and trace elements contained in both Secunda fresh fly ash and Secunda weathered fly ash could leach upon exposure to different environmental conditions. The elements showed partitioning between five geochemical phases i.e. water soluble fraction, exchangeable fraction, carbonate fraction, Fe & Mn fraction and residual fraction. The labile phases consisted of the water soluble fraction, exchangeable fraction and carbonate fraction. The % leached out in the labile phases was expressed as a fraction of each element‟s total content e.g. Si (6.15 %) meant that 6.15 % of the total amount of Si in the ash was released in the labile phases. Na was the most labile among the major elements in the ash dam while Si and Al which form the major aluminosilicate ash matrix also showed significant lability. The % leached out in the labile phases for these major elements was as follows: for Secunda fresh ash: Si (6.15 %), Al (7.84 %), Na (11.31 %); for weathered Secunda ash core samples (n = 35): Si (7.53 %), Al (8.12 %), Na (11.63 %). This study showed that the fly ash generated at Sasol Secunda power station could not be used as a long term sustainable salt sink. The wet disposal method used at Sasol Secunda power station poses a high risk of groundwater contamination due to the high liquid to solid ratio used to transport the ash for disposal, which may lead to rapid dissolution of all the soluble components in the fly ash. The large volumes of brine that pass through Secunda ash dam in the wet ash handling system present a greater environmental concern than the dry ash handling system which involves small amounts of brine entering the ash dump.

AN ABSTRACT OF THE THESIS OF Amberly Hope Tobin, for the Master of Science degree in Organic Geochemistry, presented on August 4th 2016, at Southern Illinois University Carbondale. TITLE: OHD PROCESSING OF COAL WASTE MATERIALS MAJOR PROFESSOR: Dr. Susan M. Rimmer This research addresses coal-waste utilization via the OHD process and the implications for both economic and environmental impacts. The goal of this project is to determine if coal-waste products can be processed by the OHD technique. Furthermore, this project will determine what types of products are produced from the coal-waste materials and will compare these to those produced by the OHD processing of raw coal. This research has the potential to be beneficial to the coal industry as OHD would allow production of high-value products from what is currently viewed as a waste material; additionally, this research will provide a way to recycle what is considered a hazardous waste product and provide an incentive to reclaim coal slurry ponds that are an environmental concern. A preliminary suite of grab samples from an active coal slurry pond along with a stream reject sample were obtained in order to determine if these types of materials could be processed via OHD. After these samples were deemed viable in the OHD process, core samples were taken from a large slurry pond. These cores were then ii sampled at 2 ft (0.61 m) intervals. The key analyses performed were geochemical, petrographic, OHD, and GC-MS. Geochemical analysis included carbon, sulfur, moisture, volatile matter, ash, and fixed carbon content of the coal-waste samples before OHD, and provided a basis for comparison with raw coal samples. Petrographic analysis was performed to determine the maceral composition before the OHD processing. The OHD process is the core technique of this research project. The preliminary slurry pond samples were processed in a small semi-continuous OHD reactor. While the stream reject and slurry pond core samples were processed using a continuous OHD reactor, as this type of reactor is best suited for fine-grained slurries. GC-MS was used to examine the OHD liquid products analysis in order to determine the types of compounds present in the final liquefied product; these products were then compared to raw coal OHD products in order to determine their economic potential. Petrography of the coal-waste materials showed that these samples did contain a notable amount of coal; predominantly vitrinites and inertinites were observed in the samples. Geochemical analysis proved that there were significant amounts of organic carbon in these materials, ranging between 25 and 37%. OHD processing was successful on all coal-waste materials, although the continuous OHD reactor tended to work better with the fine-grained slurries than the semi-continuous OHD reactor. The GC-MS analysis of the coal-waste OHD product showed very similar suites of compounds to that of a bulk coal OHD product; in general, almost all major compounds that are found in a typical coal OHD product were also found in the coal-waste OHD products. This suggests that these slurry ponds, which are typically regarded as waste products, could be viable feedstocks for OHD processing.

Este estudo foi feito a partir de uma amostra de carvão extraído na mina da Vale- Moçambique, localizada no distrito de Moatize, Província de Tete. O trabalho visa analisar o sistema de reagentes na flotação de finos de carvão mineral pertencente à camada UCB. Dentre os métodos de beneficiamento de carvão, a flotação se destaca como um dos mais importantes para a concentração deste material, em particular no tratamento de partículas finas. A alimentação total da planta de processamento da Vale- Moçambique é de 8000 tph de carvão, onde 10% dessa alimentação corresponde a fração fina que alimenta o circuito de flotação. O material utilizado nesse estudo apresentou uma granulometria 96% menor do que 0,25 mm. Os reagentes utilizados nos ensaios de flotação foram betacol e óleo diesel como agentes hidrofobizantes e MIBC como espumante. O intervalo de concentrações de betacol na primeira fase de ensaios foi de 200 g/t a 500 g/t, e na segunda fase foi de 200 g/t a 500g/t de óleo diesel e manteve-se constante o MIBC em 300 g/t. Os resultados mostraram que é possível, a partir de uma alimentação com o teor de cinzas em torno de 22,84%, obter produtos com teores abaixo de 10% de cinzas, com uma recuperação mássica em torno de 50%. A recuperação de matéria carbonosa também foi avaliada e apresentou resultados positivos. Complementando esse estudo, foi avaliado o efeito da recuperação de H2O e foi observado que para as concentrações de betacol as recuperações variaram de 6 a 9%, e para óleo diesel mais MIBC foram de 4 a7%. / This study was done from a sample of coal mined at the Vale-Mozambique mine, located in Moatize district, Tete Province. The aim of this work is to analyze the reagent system in the flotation of coal fines belonging to the UCB layer. Among coal processing methods, flotation stands out as one of the most important for the concentration of this material, in particular in the treatment of fine particles. The total feed of the Vale-Mozambique processing plant is 8000 tph of coal, where 10% of this feed corresponds to the fine fraction that feeds the flotation circuit. The material used in this study had a particle size of 96% smaller than 0.25 mm. The reagents used in the flotation tests were betacol and diesel oil as hydrophobizing agents and MIBC as frother. The range of betacol concentrations in the first test phase was 200 g / t at 500 g / t, and in the second phase 200 g / t at 500 g / t of diesel oil and MIBC were kept constant at 300 g / t. The results showed that it is possible, from a feed with the ash content around 22.84%, to obtain products with levels below of 10% ash, with a mass recovery around 50%. The recovery of carbonaceous matter was also evaluated and presented positive results. Complementing this study, the effect of H2O recovery was evaluated and it was observed that for the concentrations of betacol the recoveries ranged from 6 to 9%, and for diesel oil plus MIBC were 4 to 7%.

Este estudo foi feito a partir de uma amostra de carvão extraído na mina da Vale- Moçambique, localizada no distrito de Moatize, Província de Tete. O trabalho visa analisar o sistema de reagentes na flotação de finos de carvão mineral pertencente à camada UCB. Dentre os métodos de beneficiamento de carvão, a flotação se destaca como um dos mais importantes para a concentração deste material, em particular no tratamento de partículas finas. A alimentação total da planta de processamento da Vale- Moçambique é de 8000 tph de carvão, onde 10% dessa alimentação corresponde a fração fina que alimenta o circuito de flotação. O material utilizado nesse estudo apresentou uma granulometria 96% menor do que 0,25 mm. Os reagentes utilizados nos ensaios de flotação foram betacol e óleo diesel como agentes hidrofobizantes e MIBC como espumante. O intervalo de concentrações de betacol na primeira fase de ensaios foi de 200 g/t a 500 g/t, e na segunda fase foi de 200 g/t a 500g/t de óleo diesel e manteve-se constante o MIBC em 300 g/t. Os resultados mostraram que é possível, a partir de uma alimentação com o teor de cinzas em torno de 22,84%, obter produtos com teores abaixo de 10% de cinzas, com uma recuperação mássica em torno de 50%. A recuperação de matéria carbonosa também foi avaliada e apresentou resultados positivos. Complementando esse estudo, foi avaliado o efeito da recuperação de H2O e foi observado que para as concentrações de betacol as recuperações variaram de 6 a 9%, e para óleo diesel mais MIBC foram de 4 a7%. / This study was done from a sample of coal mined at the Vale-Mozambique mine, located in Moatize district, Tete Province. The aim of this work is to analyze the reagent system in the flotation of coal fines belonging to the UCB layer. Among coal processing methods, flotation stands out as one of the most important for the concentration of this material, in particular in the treatment of fine particles. The total feed of the Vale-Mozambique processing plant is 8000 tph of coal, where 10% of this feed corresponds to the fine fraction that feeds the flotation circuit. The material used in this study had a particle size of 96% smaller than 0.25 mm. The reagents used in the flotation tests were betacol and diesel oil as hydrophobizing agents and MIBC as frother. The range of betacol concentrations in the first test phase was 200 g / t at 500 g / t, and in the second phase 200 g / t at 500 g / t of diesel oil and MIBC were kept constant at 300 g / t. The results showed that it is possible, from a feed with the ash content around 22.84%, to obtain products with levels below of 10% ash, with a mass recovery around 50%. The recovery of carbonaceous matter was also evaluated and presented positive results. Complementing this study, the effect of H2O recovery was evaluated and it was observed that for the concentrations of betacol the recoveries ranged from 6 to 9%, and for diesel oil plus MIBC were 4 to 7%.