Download or read book Surface Properties of Photo oxidized Bituminous Coals written by and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Surface Properties of Photo Oxidized Bituminous Coals written by and published by . This book was released on 1998 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: Natural weathering has a detrimental effect on the hydrophobic nature of coal, which in turn can influence clean-coal recovery during flotation. Few techniques are available that can establish the quality of coal surfaces and that have a short analysis time to provide input for process control. Luminescence emissions which can be quantified with an optical microscope and photometer system, are measurably influenced by degree of weathering as well as by mild storage deterioration. In addition, it has been shown that when vitrinite is irradiated with a relatively high intensity flux of violet- or ultraviolet- light in the presence of air, photo-oxidation of the surface occurs. The combination of measuring the change in luminescence emission intensity with degree of surface oxidation provided the impetus for the current investigation. The principal aim of this research was to determine whether clear correlations could be established among surface oxygen functionality, hydrophobicity induced by photo-oxidation, and measurements of luminescence intensity and alteration. If successful, the project would result in quantitative luminescence techniques based on optical microscopy that would provide a measure of the changes in surface properties as a function of oxidation and relate them to coal cleanability. Two analytical techniques were designed to achieve these goals. Polished surfaces of vitrain bands or a narrow size fraction of powdered vitrain concentrates were photo-oxidized using violet or ultraviolet light fluxes and then changes in surface properties and chemistry were measured using a variety of near-surface analytical techniques. Results from this investigation demonstrate that quantitative luminescence intensity measurements can be performed on fracture surfaces of bituminous rank coals (vitrains) and that the data obtained do reveal significant variations depending upon the level of surface oxidation. Photo-oxidation induced by violet or ultraviolet light fluxes does result in a progressive and significant increase in the amount of near-surface oxygen concentration at about the same level regardless of bituminous coal rank. These incremental changes in oxygen concentration appear to lower the hydrophobicity as shown by contact angle measurements on polished surfaces. Although this influence diminished as coal rank increased, the level of oxygen uptake was about the same, suggesting that the type of oxygen functionality formed during oxidation may be of great importance in modifying surface hydrophobicity. Changes in functional-group chemistry, measured by a variety of near-surface techniques, showed a general increase in the concentration of carbonyl-containing groups while those of CH2 groups decreased. All of these observations follow the trends observed in previous investigations of naturally weathered coals. The photo-oxidation technique also resulted in the development of phenolic, ester and anhydride moieties instead of the expected emplacement of carboxylic acid groups which are normally associated with naturally weathered coals. The importance of this observation is that esters and anhydrides would result in a more hydrophobic surface in comparison to the more hydrophilic surface resulting from acid functionality. This observation is consistent with the results of film flotation of UV-irradiated powdered vitrain in which floatability was generally observed to increase with increasing photo- oxidation.

Download or read book Surface Properties of Photo oxidized Bituminous Coals Quarterly Technical Report October 1 1996 December 31 1996 written by and published by . This book was released on 1997 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: During this reporting period, three vitrain concentrate samples crushed to -200 mesh were irradiated (photo-oxidized) for different time periods (0, 10, 50 and 100 min) using the BLAK-RAY ultraviolet lamp to obtain samples suitable for pyrolysis GC/MS. These samples will be used to investigate whether the levels of photo-oxidation induced with increasing UV irradiation can be detected and measured in bulk vitrains using the technique. The analyses have not been fully completed. Further, additional analysis of reflectance-mode FTIR results obtained from polished blocks of vitrain is currently under way. This evaluation involves calculating the second derivative of the spectra in an attempt to better identify the spectral regions of most significant change resulting from photo-oxidation. These analyses, along with final analytical tests that will destroy the irradiated surfaces, including electron microprobe analysis for near- surface oxygen concentration and x-ray mapping, and measurement of reflectance in oil immersion, are under way and will be completed by the end of February, 1997. During this report period we have begun the preparation of a manuscript tentatively entitled, ''Time Resolved C-NEXAFS Analysis of the Chemistry of Photochemical Alteration of Vitrinite. This publication will discuss our efforts in utilizing Scanning Transmission X-ray Microscopy as a tool to better define the kinetics of photo-oxidation or vitrinite from coals of three different ranks by measuring changes in regions near the carbon-edge absorption.

Download or read book Surface Properties of Photo oxidized Bituminous Coals Technical Progress Report September November 1993 written by and published by . This book was released on 1993 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Five of the eight coals to be studied in this project have been selected on the basis of economic importance as well as geologic and chemical histories. Plans have been initiated to collect the first sample, a Pittsburgh seam coal from southwestern Pennsylvania. However, we have as yet not received permission from the mine to collect our working face sample. In addition, preliminary work was completed on development and testing of a procedure to photo-oxidize vitrinite containing coal blocks using the optical microscope.

Download or read book Surface Properties of Photo oxidized Bituminous Coals Technical Progress Report October December 1995 written by and published by . This book was released on 1996 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: During this report period, polished blocks of coal containing 3--4 mm wide vitrain bands were prepared for contact angle measurements of fresh and photo-oxidized surfaces using the advancing-drop technique. Contact angles were measured on two of the coals collected for this study, (the Ohio No. 4a (DECS-33) and Lower Kittanning (PSOC-1562) seams) and the results added to those presented in the last quarterly report. Although the new data give additional variation to the sample set, they are consistent with the original observations, i.e., that contact angle is influenced by irradiation time and coal rank. Using the maximum change in contact angle measured between fresh and photo-oxidized surfaces, a linear decrease is observed with increasing rank resulting from 5 and 10 minutes of irradiation. The magnitude of the decrease in contact angle diminishes with increasing rank. Also during this period, an ultraviolet spotlight was evaluated as a means of irradiating powdered vitrain. This 100 watt, long wavelength (366 nm) ultraviolet lamp is to be used in place of the optical microscope system to establish the influence of surface photo-oxidation on the flotation characteristics of vitrain concentrates. A series of experiments was designed to determine the magnitude of change in the luminescence intensity (at 600 nm measured in the optical microscope) with exposure to the ultraviolet light with time for vitrinite from different rank coals. The authors have established that there is a significant decrease in luminescence intensity with time of exposure which diminishes slightly as rank increases. The ultraviolet light appears to provide a level of photo-oxidation that is a factor of 10 lower than that obtained with their optical microscope system.

Download or read book Surface Properties of Photo oxidized Bituminous Coals Technical Progress Report July September 1995 written by and published by . This book was released on 1995 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: During this report period, a new whole-seam channel sample (Ohio {number_sign}4a) was collected and analyzed, together with the Upper Banner and Splash Dam samples obtained last quarter. These additions bring to seven the number of coals obtained for this project and that range in rank from hvCb to mvb. Polished blocks of each coal containing 3-4 mm wide vitrain bands were prepared for contact angle measurements of fresh and photo-oxidized surfaces. An advancing-drop technique was used to measure contact angle. In this test a droplet of distilled water is grown initially on fresh surfaces and then moved across those irradiated in blue-light for 1, 5, and 10 minutes. The sequence of growth was recorded on video tape, and the change in contact angle measured relative to position at the air/water/surface interface. Contact angles were measured on five of the coals collected for this study, namely the Illinois {number_sign}6, Ohio {number_sign}4a, Lower Kittanning (PSOC-1563), Pittsburgh and Splash Dam seams. Preliminary results show that both coal rank and irradiation time influence surface wettability as measured by contact angle. With one exception, contact angle values decreased and remained low when the droplet advanced into an irradiated area. In most cases, one minute of irradiation resulted in only a slight decrease in contact angle, whereas after 5 and 10 minutes a more significant decrease was observed. The magnitude of change in contact angle values with degree of photo-oxidation decreased as rank increased, such that lower rank bituminous coals show the greatest change and medium volatile coal the least.

Download or read book Surface Properties of Photo oxidized Bituminous Coals Technical Progress Report December 1993 March 1994 written by and published by . This book was released on 1994 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the report period, channel and block samples of the Pittsburgh seam (DECS-23) were collected from Consolidation Coal Company's Bailey Mine and were subsequently processed and partly analyzed. Powdered vitrinite concentrates were prepared from the block samples in a nitrogen-filled glovebox, and small coal blocks containing (approximately)5 mm thick vitrain bands were cut from the larger sections. Results of proximate, ultimate and petrographic analyses showed that the concentrate contained 97% (by volume, dmmf) vitrinite and about 3% (by weight) pyrite. On the basis of fluorescence intensity and alteration measurements, the coal and concentrate appeared to be extremely fresh, exhibiting no signs of oxidation or deterioration. A polished surface of one of the small coal blocks was prepared and photo-oxidized in order to evaluate reflectance-mode FTIR equipment and techniques, as well as for the measurement of contact angles. Photo-oxidation of this sample was accomplished by blue-light irradiation. In addition, arrangements are being made for the collection of two Lower Kittanning seam coal samples (marine- and freshwater-influenced) from northwestern Pennsylvania.

Download or read book Surface Properties of Photo oxidized Bituminous Coals Technical Progress Report for the Period July September 1996 written by and published by . This book was released on 1996 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: During this report period, irradiation (photo-oxidation) of all six vitrain concentrates for three different time periods (10, 50 and 100 min) using the BLAK-RAY ultraviolet lamp was completed along with film flotation and surface luminescence measurements for each condition. Flotation results from photo-oxidized powdered vitrains appear to be contrary to earlier results obtained from contact angle measurements on polished surfaces. Some of the more strongly photo-oxidized powders, particularly for hvAb and mvb coals, exhibit greater hydrophobicity. The changes in hydrophobicity as well as a measured decrease in surface luminescence with increasing irradiation time, clearly shows that UV irradiation has had an influence on surface properties. There is some possibility that increasing exposure to the UV source may cause mobilization of aliphatic compounds (oils) from the fresh fracture surfaces of vitrain. These compounds, once exuded onto the surface could act like a natural flotation collector that would both increase particle hydrophobicity and may obscure the surface from further oxidation. Because most aliphatic compounds do not luminesce, their presence on the surface would reduce measured luminescence. A second possible explanation is that the types of oxygen functional groups which form during UV irradiation may inhibit or promote hydrophobicity depending upon their concentration. In an attempt to resolve these issues several analytical tests will be undertaken. Pyrolysis GC/MS will be used to investigate whether photo-oxidation of bulk vitrains was sufficiently severe with increasing UV irradiation. Reflectance-mode FTIR will be used to measure changes in surface chemistry for some of the irradiated powdered vitrains.

Download or read book Surface Properties of Photo oxidized Bituminous Coals Technical Progress Report April 1995 June 1995 written by and published by . This book was released on 1995 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: During this report period, analysis of the vitrinite concentrate samples of the Lower Kittanning (PSOC-1562) and Illinois No. 6 (DECS-24) seams were completed. These results show that the concentrates are in excess of 97 vol. % vitrinite and that the sample remains in good shape for microflotation and GC/MS experiments. Two new coal samples, the hvAb Banner seam (DECS-29) and the mvb Splashdam seam (DECS-30) were collected in mid-June. Preliminary processing of the channel samples suggests that the Banner seam sample is severely weathered and may need to be replaced. Collection of a third sample, the hvBb Ohio No. 4a seam, was delayed until next quarter. Surface oxidation of a powdered vitrinite concentrate sample of the Pittsburgh seam (DECS-23) was completed during this quarter. The technique of photo-oxidizing vitrain samples using our optical microscope was laborious and time consuming. Even after the procedure was streamlined the procedure of irradiating 1.4 g of vitrinite required 29 days. A limited number of samples will be irradiated in this manner in order to maintain continuity between our fluorometric measurements and microflotation experiments, but other methods of surface oxidation will be explored. Presentations were made at the DOE Contractor's Review and Peer Review meetings held in Nashville, TN on June 13-14, 1995.

Download or read book Surface Properties of Photo oxidized Bituminous Coals Technical Progress Report for the Period April to June 1996 written by and published by . This book was released on 1996 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: During this report period, two vitrinite concentrates were prepared and analyzed from the hvBb Ohio No. 4a and hvAb Lower Kittanning seams. Results show that concentrates of 97 and 96 vol% vitrinite were achieved for the respective samples. Both samples have relatively high concentrations of sulfate sulfur which is the only sign of deterioration. However, in the case of the Lower Kittanning sample the sulfate may have been part of the original sample. Irradiation (photo-oxidation) of all six vitrinite concentrates for three different time periods (10, 50 and 100 min) using a ultraviolet lamp was continued during this report period. Evaluation showed that these irradiation times provided a level of photo-oxidation that corresponded to the blue-light flux used in the optical microscope system for 1, 5 and 10 min irradiations, respectively. From evaluation of the surface luminescence of vitrain surfaces following exposure to UV light the authors have determined the intensity decreases with increasing irradiation time. Film flotation results, although incomplete, show that there is some variability in flotation yield as a function of rank and of photo-oxidation time. As observed from contact angle and FTIR spectral measurements on polished surfaces, the hvCb Illinois No. 6 powdered vitrain shows a significant loss in flotation yield with increasing irradiation time following 10 and 50 min of exposure to UV light. Also, a relative minor change in flotation yield was observed for the mvb Splash Dam vitrain powder after 10 and 50 min irradiation. The Splash Dam vitrain gave a slight increase in flotation yield suggesting that the surface became somewhat more hydrophobic. Results from the hvAb Lower Kittanning sample appear intermediate. A significant increase in flotation yield occurs after 10 min irradiation marked by a relatively large decrease after 50 min.

Download or read book Surface Properties of Photo oxidized Bituminous Coals Technical Progress Report January 1995 March 1995 written by and published by . This book was released on 1995 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: During this report period, vitrinite concentrate samples were prepared from the Illinois No. 6 (DECS-24) and Lower Kittanning (PSOC-1562) seam samples that were collected last year. Some of the analytical information on these concentrates are provided. In addition, preparation of a surface-oxidized powdered vitrinite concentrate of the Pittsburgh seam (DECS-23) sample for microflotation experiments and pyrolysis GC/MS was initiated following development of a procedure for the irradiation sequence for this sample. Our collaborative efforts with Dr. Pigram of the University of New South Wales and Dr. Cody of Argonne National Laboratory have continued. As a result of problems in relocating the irradiated areas prepared for Scanning Ion Mass Spectroscopy (SIMS), a new sample preparation technique was developed. This procedure involves the use of a finder grid that is attached to the coal surface allowing Dr. Pigram's group to positively identify the affected area. A new ultrathinned section of the medium volatile Sewell seam (DECS-13) was prepared for Scanning Transmission X-ray Microscopy (STXM) and analyzed. Preliminary findings suggest the changes in oxygen functionality on the irradiated surfaces (1, 5 and 10 mins) of this coal compare well with that previously reported for the subbituminous Wyodak and high volatile Pittsburgh seam discussed in the last quarterly report. Kinetic data from evaluation of carbon near-edge x-ray adsorption fluorescence spectroscopy (C-NEXAFS) has yet to be completed.

Download or read book Surface Properties of Photo oxidized Bituminous Coals Technical Progress Report January March 1996 written by and published by . This book was released on 1996 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: During this report period, a vitrinite concentrate from the mvb Splash Dam seam (DECS-30) was prepared and analyzed. Results show that the concentrate was 91 vol % vitrinite and that the sample has been adequately protected from oxidation under refrigerated storage in argon. The 9% level of contamination within the vitrinite resulted from the extreme friability of the coal and to the dispersion of fine grains of semifusinite and micrinite. Polished blocks containing vitrain bands that were prepared, irradiated in blue-light and employed in contact angle measurements were evaluated using specular reflectance-mode FT-IR for changes in functional group chemistry. Infrared spectra from unexposed areas of vitrinite and those irradiated for 1, 5 and 10 min for six coals ranging in rank from hvCb to mvb were obtained using a FTS 175 spectrometer with a Bio-Rad UMA 500 microscope accessory. Preliminary results demonstrate that photo-oxidation occurred during irradiation, becoming progressively more intense with increasing irradiation time; however, the magnitude of this change diminished with increasing rank. A relatively steady increase in the carbonyl region (1,800--1,650 cm−1) and a decrease in the aliphatic region (2,950--2,850 cm−1) of the spectra supports this observation and is similar to observations made in the past for natural weathering and laboratory oxidation of coals. A series of tests was initiated to photo-oxidize powdered vitrains using the BLAK-RAY ultraviolet lamp evaluated last quarter. Samples of four vitrinite concentrates were exposed to UV light for 10 mins per side. These and the corresponding whole-seam channel samples and raw vitrinite concentrates were submitted for initial microflotation tests which have not been completed at this time.

Download or read book Surface Propeties of Photo oxidized Bituminous Coals Technical Progress Report January 1995 March 1995 written by and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Surface Properties of Oxidized Coal written by John Michael Rosenbaum and published by . This book was released on 1980 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1994-08 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Further Studies of the Effects of Oxidation on the Surface Properties of Coal and Coal Pyrite written by Miguel Nicholas Herrera and published by . This book was released on 1994 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Surface Properties of Coal and Their Role in Fine Coal Processing written by Jianli Diao and published by . This book was released on 1990 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: