The paper discusses a two-step process for the simultaneous extraction of graphene quantum dots and chemicals. The two steps are sequential structure disruption by supercritical CO2 explosion followed by a low temperature (120oC), non-catalytic transfer hydrogenation in supercritical CO2. The key idea of this research is, one hydrogen atom from hydrogen transfer agent (HTA) one hydrogen atom from water is used to hydrogenate the coal. The use of supercritical CO2 enhances the rate of hydrogenation, helps in dissolution of non-polar molecules and removal from the reaction site. The coal dissolution products are polar and non-polar. A phase transfer agent (PTA) allows seamless transport of the ions and byproduct between the aqueous and organic phases. A polar modifier (PM) for CO2 has been added to aid in the dissolution and removal of the polar components. The effect of feed conditions on the liquefaction process has been investigated. The response metrics considered were the conversion of coal and the yields of various organic classes such as ketones, alkanes, alkenes, aliphatic acids, alcohols, amines, aromatics and aromatic oxygenates. Ketones were found to be the major constituent of the products. Graphene quantum dots were also extracted.

Made available in DSpace on 2014-06-11T19:35:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-07-11Bitstream added on 2014-06-13T18:47:03Z : No. of bitstreams: 1 silva_am_dr_guara.pdf: 5117033 bytes, checksum: 08f0d4a636d759ed0ecac8bcba9c1f7d (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Esse trabalho tem como objetivo estudar a utilização da biomassa em substituição parcial ao carvão mineral utilizado no processo de fabricação do ferro gusa em altoforno, assim como, a sua influência na qualidade do coque. Este estudo foi desenvolvido em quatro fases, sendo elas: 1ª FASE: Foram utilizados nas misturas de carvão a sacarose, o melaço e o carvão da casca de coco em percentuais de 5% a 75%. Os resultados de qualidade das misturas e dos coques produzidos mostram uma forte influência da biomassa na qualidade para os níveis de participação acima de 5,0%, inviabilizando a mistura desses materiais no carvão. 2ª FASE: Foram utilizados nas misturas de carvão um segundo grupo de biomassas cujo percentual variou de 2% a 6%. Os resultados de qualidade tanto das misturas quanto dos coques produzidos em escala piloto foram aceitáveis para as misturas com 2,0% de participação das biomassas. 3ª FASE: Nessa fase foi feita a avaliação do efeito da biomassa na eficiência de queima das misturas de carvão injetadas em altos fornos. Os resultados indicaram um aumento da eficiência de queima para as misturas com maior teor de matéria volátil. 4ª FASE: Foi realizada a avaliação da qualidade do coque produzido em escala industrial utilizando as misturas dos carvões minerais com as biomassas com participação de 3%, 4% e 6%. Os resultados da qualidade dos coques obtidos em escala industrial ficaram compatíveis com os resultados obtidos em escala piloto. A substituição em até 2,0% do carvão mineral por carvão de biomassa não afetou a qualidade do coque produzido nas baterias, onde em uma empresa siderúrgica do porte da CSN é possível obter uma redução de consumo de carvão mineral em torno de 50 mil toneladas por ano e conseqüentemente uma redução no custo de fabricação do ferro-gusa no alto-forno. / This work has as purpose to study the use of biomass as partial replacement to the coal used during the process of pig iron manufactured in blast furnace. This study was developed in four phases, namely: 1st PHASE: The coal blend with sucrose, molasses, and the charcoal from coconut peel were elaborated and testes in percents from 5 to 75%. The results of quality from mixes and the coke produced show a strong influence of the biomass on the quality for the participation level higher than 5.0%, making infeasible the mix of these materials into the coal in elevate percents. 2nd PHASE: In the coal blend, a second group of biomasses was used, which percent varied from 2% to 6%; The quality results both of mixes and coke produced in pilot scale were acceptable for the addition level of 2,0%. 3rd PHASE: It was elaborated the evaluation of the biomass effect in the burn efficiency for the coal mixes injected in blast furnaces. The results indicated an efficiency increase of burn for the mixes with high content of volatile matter. 4th PHASE: The coke production was performed in industrial scale using coal blends with the biomasses with participation in up to 6.0%. The quality results of coke obtained in industrial scale were compatible with the results obtained in pilot scale. The replacement in up to 2.0% of the coal by biomass charcoal did not affect the coke quality produced on the batteries, where, in steel industry company with CSN’s size, it is possible to obtain by means of coal replacement by biomass charcoal a reduction of 50 thousand tons/year in the consumption of coal and therefore, a reduction on the manufacturing cost of pig iron in the blast furnace.

Thesis (MTech (Chemistry))--Cape Technikon, Cape Town, 2002 / The aim of the study was to develop an understanding of fine coal flotation emphasizing developing methodology capable of selecting the optimum flotation reagent. A secondary aim was to use the experimental data in a statistical program to validate the findings and investigate correlations between flotation performance and coal characteristics. The predictions that were made from the coal characterisation results were confirmed. Oleic acid, iso-decanol and dodecene resulted in the best flotation performance on the coal samples that were evaluated. This is in agreement with previous research findings, that oleic acid is a good collector for coal and that branched hydrocarbons also increase flotation yields. The ability of unsaturated hydrocarbons to increase flotation yield was also confirmed. The study included 5 coal samples from different collieries - Twistdraai (Highveld seam 3 and 4), Waterberg (Zone 10 -11), Syferfontein seam 5 upper (Highveld) and Witbank seam 2 and seam 4. Twistdraai, Waterberg and Syferfontein seam 5 upper were all found to be vitrinite rich coals. The Witbank coals are both more inertinite rich. The feed ash contents determined for the flotation feed samples were 28.8% for Twistdraai coal, 13.9% for Syferfontein seam 5 upper, 28.8% for Waterberg coal, 16.1% for Witbank seam 2 coal and 33.8% for Witbank seam 4 coal. The coal characterisation study included petrographic analysis, proximate analysis, float-sink analysis, oxygen-containing functional groups, surface extraction, flotation release analysis and contact angle measurements.

Orientador: João Andrade de Carvalho Junior / Banca: José Antonio Perrella Balestierii / Banca: Maurício Araújo Zanardi / Banca: José Adilson de Castro / Banca: Eduardo Osório / Resumo: Esse trabalho tem como objetivo estudar a utilização da biomassa em substituição parcial ao carvão mineral utilizado no processo de fabricação do ferro gusa em altoforno, assim como, a sua influência na qualidade do coque. Este estudo foi desenvolvido em quatro fases, sendo elas: 1ª FASE: Foram utilizados nas misturas de carvão a sacarose, o melaço e o carvão da casca de coco em percentuais de 5% a 75%. Os resultados de qualidade das misturas e dos coques produzidos mostram uma forte influência da biomassa na qualidade para os níveis de participação acima de 5,0%, inviabilizando a mistura desses materiais no carvão. 2ª FASE: Foram utilizados nas misturas de carvão um segundo grupo de biomassas cujo percentual variou de 2% a 6%. Os resultados de qualidade tanto das misturas quanto dos coques produzidos em escala piloto foram aceitáveis para as misturas com 2,0% de participação das biomassas. 3ª FASE: Nessa fase foi feita a avaliação do efeito da biomassa na eficiência de queima das misturas de carvão injetadas em altos fornos. Os resultados indicaram um aumento da eficiência de queima para as misturas com maior teor de matéria volátil. 4ª FASE: Foi realizada a avaliação da qualidade do coque produzido em escala industrial utilizando as misturas dos carvões minerais com as biomassas com participação de 3%, 4% e 6%. Os resultados da qualidade dos coques obtidos em escala industrial ficaram compatíveis com os resultados obtidos em escala piloto. A substituição em até 2,0% do carvão mineral por carvão de biomassa não afetou a qualidade do coque produzido nas baterias, onde em uma empresa siderúrgica do porte da CSN é possível obter uma redução de consumo de carvão mineral em torno de 50 mil toneladas por ano e conseqüentemente uma redução no custo de fabricação do ferro-gusa no alto-forno. / Abstract: This work has as purpose to study the use of biomass as partial replacement to the coal used during the process of pig iron manufactured in blast furnace. This study was developed in four phases, namely: 1st PHASE: The coal blend with sucrose, molasses, and the charcoal from coconut peel were elaborated and testes in percents from 5 to 75%. The results of quality from mixes and the coke produced show a strong influence of the biomass on the quality for the participation level higher than 5.0%, making infeasible the mix of these materials into the coal in elevate percents. 2nd PHASE: In the coal blend, a second group of biomasses was used, which percent varied from 2% to 6%; The quality results both of mixes and coke produced in pilot scale were acceptable for the addition level of 2,0%. 3rd PHASE: It was elaborated the evaluation of the biomass effect in the burn efficiency for the coal mixes injected in blast furnaces. The results indicated an efficiency increase of burn for the mixes with high content of volatile matter. 4th PHASE: The coke production was performed in industrial scale using coal blends with the biomasses with participation in up to 6.0%. The quality results of coke obtained in industrial scale were compatible with the results obtained in pilot scale. The replacement in up to 2.0% of the coal by biomass charcoal did not affect the coke quality produced on the batteries, where, in steel industry company with CSN's size, it is possible to obtain by means of coal replacement by biomass charcoal a reduction of 50 thousand tons/year in the consumption of coal and therefore, a reduction on the manufacturing cost of pig iron in the blast furnace. / Doutor

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No description available.

In order to mine coal, South African surface coal mining operations are heavily dependent on their earthmoving equipment fleets. These equipment fleets represent large capital investments by the companies. Mine management must make complex decisions on their deployment, maintenance, and retirement. They have finite physical and economic life and require replacement at some stage. However, different methodologies are employed to determine the timing of earthmoving equipment replacements. These vary from complex financial models to an intuitive knowledge that a machine must be replaced at a particular time. This study investigated the replacement of earthmoving equipment at coal mining companies and contract earthmoving companies. It also explored the recommendations of the equipment suppliers. This was done by conducting in-depth interviews with five coal mining companies, four contractor companies and three equipment suppliers. The results showed that large companies do economic analysis, as recommended by the equipment suppliers. They incorporate the quantifiable factors of increased maintenance cost, decreased performance and technological improvements. Smaller coal mining companies and contractor companies generally only consider historical cost and performance trends and there is scope for improving the replacement decision of their earthmoving equipment. / Dissertation (MBA)--University of Pretoria, 2010. / Gordon Institute of Business Science (GIBS) / unrestricted

No description available.

The physical environment of the Nanaimo area, inland forms, climate, soils and vegetation, is similar to that of the eastern coastal plain region of Vancouver Island. Two resources have/influenced the occupance particularly: coal deposits and location. The distributing economy made possible by location is still developing, but the economy as sociated with coal-mining has lost its former dominance. The effects which coal-mining, and adaptation to its decline, have had upon the economic life, the cultural landscape and the population can be studied as a phase in a continuing process of interaction between man and his environment. Physical factors have placed limitations upon the development of local activities. Location, which both fostered and hindered the progress of coal-mining, is becoming an increasingly important asset. Geological conditions proved disadvantageous to the prosperity of mining and limited the span of its productivity. Topography, soil and drainage restricted the scope of agriculture. The volume of local timber reserves confines their exploitation to small-scale operations, but the large reserves in surrounding areas form the basis of the whole regional economy. Fishing makes its greatest economic contribution in directly. Coal-mining expanded slowly from 1852 until the 1880's. The thirty years following 1890 marked the period of greatest employment and productivity, but it was interrupted by recessions due to the competition of other fuels and to labour difficulties. Decline since 1923 has been rapid and steady. The coal resources are now exploited on a continuously declining scale. Other economic activities have been further influenced by their changing relationships to coal-mining. Because of its early start, agriculture has nearly reached the limits of its areal expansion, part-time farming, by which land is used less intensively, has also been encouraged by the mining industry The depletion of timber reserves is directly attributable to the demands of the coal-mining economy. Certain manufacturing industries developed to serve the mining community, have disappeared, but others have expanded slightly Only those dependent upon resources located outside the area are likely to develop significantly. The tertiary industries of the coalmining period formed the nucleus of the present distributing economy. Favoured by location, they have become the mainstay of the area and have possibilities of further expansion. The features of the cultural landscape which originated during the coal-mining period are still discernible, but are being obscured by those associated with the distributing economy. The present complex pattern of agricultural and forest land utilization has been determined by the distribution of soil classes and the relationships of these industries to coal-mining. Zones of increasingly intensive utilization, centred on Nanaimo, may be developing. Settlements, formerly located near the outcropping seams, are becoming involved in a general tendency toward radial development. Three types of street patterns have been developed in the city and its vicinity. Elsewhere, the compact street patterns of the mining period are becoming more linear. Distinctive miners' homes remain in certain localities. The growth of population, formerly related to coal-mining, has not yet significantly increased, but population distribution is changing. Movements in accordance with mining developments have ceased, and the distribution is becoming noticeably dense near Nanaimo. Mining has been replaced as the dominant occupation by the tertiary industries. The nationalities in the area still represent those attracted by the mining industry. Attitudes engendered during the mining period still persist and may have varying effects on future progress. The present economic structure is based upon a primary resource, lumber, which must compete in the world market. Although the productive capacity of the area could be improved, the greatest contribution toward future development would be the maintenance of the regional timber resources. / Arts, Faculty of / Geography, Department of / Graduate

Kinetics of steam gasification of both delayed and fluid cokes, byproducts from thermal cracking processes of Athabasca bitumen, have been studied in laboratory-size stirred and fixed bed reactors. The hydrogen sulphide in the product gas was captured in-situ using calcined dolomite and limestones as acceptors. Experiments were carried out at atmospheric pressure and at temperatures between 800°C and 930°C. The coke particle size ranged from 0.1 to 3.5 mm, and the steam partial pressure was varied from 15.15 to 60.6 kPa. The carbon and sulphur conversions were computed from the knowledge of gas compositions and flowrates and the gasification kinetics of both species established. The effects of sorbent type, particle size, calcination conditions, and Ca/S molar ratios on the extent of sulphur capture during gasification were examined in separate series of experiments. Scanning electron microscopy, surface area analysis, and mercury porosimetry were employed to relate physical structure changes in the solids to experimental kinetic data. The rate of gasification for the delayed coke was generally higher than that for the fluid coke, and both cokes were almost unreactive to steam gasification at temperatures below 800°C. Increased reaction temperatures or reduced particle sizes increased both carbon as well as sulphur conversion. The carbon conversion rates were found to go through maxima as the time of reaction and extent of conversion increased. As the reaction proceeded the surface area of the coke increased to a maximum of about five times its initial value and thenfell off sharply. The extent of carbon conversion alone dictated the specific surface area irrespective of temperature, particle size and steam partial pressure. Both calcined dolomite and calcined limestone were found to be effective in removing sulphur from the product gas. Sorbents possessing a larger specific area or smaller grain size had higher capacity to accept sulphur. At a Ca/S molar ratio of 2.0, the overall sulphur removal was approximately 90% for the first 3 hrs and the H₂S concentration in the produced gas was reduced to about 200 ppm from nearly 1250 ppm. The rate of sorbent conversion from CaO to CaS decreased monotonically with time. Three available kinetic models for gasification - the Random Capillary Model, the Random Pore Model and the Modified Volumetric Model, were tested with the experimental gasification data. Although reasonable fits were obtained for Xc-t results, the sharp drop in rate at high conversion could not be adequately modelled. Rate constants were established for the initial stage of reaction only. The Grain model and Continuous reaction models were tested with the experimental sulphidation results. The sulphidation process was controlled by chemical reaction at low sorbent conversion, and subsequently by diffusion through the product layer at higher conversions. The reaction rate constant and the effective diffusivity were accordingly established as functions of temperature. Values compared favourably with results of sulphidation kinetics done without simultaneous gasification reported in the literature. The results suggest that the gasification process and the sulphur capture process, which occur together in gasifiers with sorbent injection, can be treated independently. Indexing terms: Gasification, Carbon Conversion, Sulphur Conversion, Sulphur Removal, Calcine, Limestone, Dolomite, Hydrogen Sulphide, Sulphidation. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate