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Near Neutral Oxidation Of Pyrite In Coal Slurry Solids Quarterly Technical Report September 1 November 30 1994
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Book Synopsis Near-neutral Oxidation of Pyrite in Coal Slurry Solids. [Quarterly] Technical Report, September 1--November 30, 1994 by :
Download or read book Near-neutral Oxidation of Pyrite in Coal Slurry Solids. [Quarterly] Technical Report, September 1--November 30, 1994 written by and published by . This book was released on 1994 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this research project we plan to determine the rate of oxidation of pyrite associated with coaly particles (coal slurry solid) when the pH of the surrounding environment is held at approximately 7.8. Coaly particles that contain pyrite are generated during the preparation of Illinois Basin coal for market. These particles are discharged to an impoundment, which eventually must be reclaimed. The purpose for reclamation is either to prevent the generation of acidic solution as the pyrite in the coal slurry solid reacts with air, or to prevent the migration of the acidic solution to a groundwater aquifer. The reclamation is usually accomplished by covering the impoundment with a four-foot-thick layer of topsoil. One possible alternative method for reclamation of a coal slurry impoundment is to mix in alkaline residue from the fluidized-bed combustion of coal. This codisposal would slow the production of acid and would also neutralize any acid produced. If the codisposal method is found to be environmentally acceptable, it will save the coal mining companies part of their cost of reclamation, and also provide a safe and useful disposal outlet for a portion of the residue that is generated by the fluidized-bed combustion of coal. During this quarter we purchased and set up two automatic titrators, which will be used in determining the rate of pyrite oxidation at nearly neutral pH. The titrators will provide a means for maintaining the pH at the desired level. The rate at which sulfate ion is produced as a result of pyrite oxidation will be used to measure the amount of pyrite oxidized over time.
Book Synopsis Near-neutral Oxidation of Pyrite in Coal Slurry Solids. Quarterly Report, 1 December 1994--28 February 1995 by :
Download or read book Near-neutral Oxidation of Pyrite in Coal Slurry Solids. Quarterly Report, 1 December 1994--28 February 1995 written by and published by . This book was released on 1995 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this research project we plan to determine the rate of oxidation of pyrite associated with coaly particles when the pH of the surrounding environment is held at approximately 7.8. Coaly particles that contain pyrite are generated during the preparation of Illinois Basin coal for market. These particles are discharged to an impoundment, which eventually must be reclaimed. The purpose for reclamation is either to prevent the Generation of acidic solution as the pyrite in the coal slurry solid reacts with air, or to prevent the migration of the acidic solution to a groundwater aquifer. The reclamation is usually accomplished by covering the impoundment with a four-foot-thick layer of topsoil. One possible alternative method for reclamation of a coal slurry impoundment is to mix in alkaline residue from the fluidized-bed combustion of coal. This codisposal would slow the production of acid and would also neutralize any acid produced. If the codisposal method is found to be environmentally acceptable, it will save the coal mining companies part of their cost of reclamation, and also provide a safe and useful disposal outlet for a portion of the residue that is Generated by the fluidized-bed combustion of coal.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1994-06 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Near-neutral Oxidation of Pyrite in Coal Slurry Solids. Technical Report, March 1--May 31, 1995 by :
Download or read book Near-neutral Oxidation of Pyrite in Coal Slurry Solids. Technical Report, March 1--May 31, 1995 written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this research project are determining the rate of oxidation of pyrite associated with coaly particles (coal slurry solid) when the pH of the surrounding environment is held at approximately 7.8. Coaly particles that contain pyrite are generated during the preparation of Illinois Basin coal for market. These particles are discharged to an impoundment, which eventually must be reclaimed. The purpose for reclamation is either to prevent the generation of acidic solution as the pyrite in the coal slurry solid reacts with air, or to prevent the migration of the acidic solution to a groundwater aquifer. The reclamation is usually accomplished by covering the impoundment with a four-foot-thick layer of topsoil. One possible alternative method for reclamation of a coal slurry impoundment is to mix in alkaline residue from the fluidized-bed combustion of coal. This codisposal would slow the production of acid and would also neutralize any acid produced. If the codisposal method is found to be environmentally acceptable, it will save the coal mining companies part of their cost of reclamation, and also provide a safe and useful disposal outlet for a portion of the residue that is generated by the fluidized-bed combustion of coal. Pyrite oxidation experiments were conducted during the quarter in the following manner. Air, free of carbon dioxide, is bubbled through water in a covered beaker. The pH is adjusted to 7.8 and the solution is circulated by a peristaltic pump through the coal slurry sample contained in a cellulose thimble in a Soxhlet tube mounted above the beaker. The pH of the solution is continuously statted to 7.8 by addition of NaOH solution. Samples are pipetted from the reaction solution for sulfate determination. The rate of oxidation of pyrite in coal slurry solids sample CSS-2a was calculated from the rate of production of sulfate ion to be 1.71[times] 10[sup[minus]6][micro]mole pyrite per minute per[micro]mole of pyrite present.
Book Synopsis Government Reports Announcements & Index by :
Download or read book Government Reports Announcements & Index written by and published by . This book was released on 1995 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Near-neutral Oxidation of Pyrite in Coal Slurry Solids by :
Download or read book Near-neutral Oxidation of Pyrite in Coal Slurry Solids written by and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Control of Pyrite Surface Chemistry in Physical Coal Cleaning. Technical Progress Report for the Ninth Quarter, September 1--November 30, 1991 by :
Download or read book Control of Pyrite Surface Chemistry in Physical Coal Cleaning. Technical Progress Report for the Ninth Quarter, September 1--November 30, 1991 written by and published by . This book was released on 1992 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: The separation of pyrite from coal by flotation is based on exploiting the wettability difference between coal and pyrite. There is evidence that the wettability of coal pyrite changes upon superficial oxidation. Therefore, the oxidation of coal pyrite has been studied under carefully controlled electrochemical conditions. In order to identify the species responsible for the changes in wettability, the surface products formed during oxidation have been identified by means of various surface analysis techniques, including X-ray photoelectron spectroscopy (XPS) and ion scattering spectroscopy (ISS). It has been found that pyrite oxidation creates a sulfur-rich surface along with iron oxides/hydroxides. The ratio between these hydrophobic and hydrophilic species correlates well with the results of the wettability measurements.
Book Synopsis Controlling Incipient Oxidation of Pyrite for Improved Rejection. Eighth Quarterly Technical Progress Report, July 1, 1994-September 30, 1994 by :
Download or read book Controlling Incipient Oxidation of Pyrite for Improved Rejection. Eighth Quarterly Technical Progress Report, July 1, 1994-September 30, 1994 written by and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Oxidation of Coal and Coal Pyrite Mechanisms and Influence on Surface Characteristics. Quarterly Technical Progress Report, December 1, 1993--May 31, 1994 by :
Download or read book Oxidation of Coal and Coal Pyrite Mechanisms and Influence on Surface Characteristics. Quarterly Technical Progress Report, December 1, 1993--May 31, 1994 written by and published by . This book was released on 1996 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this research is to develop a mechanistic understanding of the oxidation of coal and coal pyrite, and to correlate the intrinsic physical and chemical properties of these minerals, along with changes resulting from oxidation, with those surface properties that influence the behavior in physical cleaning processes. The results will provide fundamental insight into oxidation, in term of the bulk and surface chemistry, the microstructure, and the semiconductor properties of the pyrite. During the fourteenth and fifteenth quarters, flotation tests were done on Upper Freeport coal from the Troutville No. 2 Mine, Clearfield County, Pennsylvania and on coal samples from the Pennsylvania State Coal Bank. The influence of electrode potential on the surface properties of coal pyrite was tested using contact angle measurements on polarized Pittsburgh coal pyrite electrode.
Book Synopsis Development of Enhanced Sulfur Rejection Processes. Final Technical Progress Report, Third Quarter (8. Quarterly Report), July 1--September 30, 1994 by :
Download or read book Development of Enhanced Sulfur Rejection Processes. Final Technical Progress Report, Third Quarter (8. Quarterly Report), July 1--September 30, 1994 written by and published by . This book was released on 1996 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pyrite becomes hydrophobic upon superficial oxidation and floats without a collector. The flotation begins to occur at potentials above the stable potentials identified by the chronoamperometry experiments conducted with freshly fractured pyrite. This finding suggests that iron polysulfide, formed during the initial stages of oxidation, is responsible for the flotation. The collectorless flotation is suppressed above the potential where the mineral is aggressively oxidized, forming iron hydroxide and soluble sulfoxy species. The collectorless flotation is less significant at pH 9.2 than at pH 4.6, possibly due to the formation of iron hydroxide. At pH 9.2, the collectorless flotation increases in the presence of EDTA and hydrocarbon oil. The collectorless flotation of pyrite can be suppressed by galvanically coupling the mineral with reactive metals such as aluminum, manganese, and zinc. This effectively prevents the mineral from oxidation. The microflotation tests conducted with mono-sized pyrite samples show that the collectorless flotation can be suppressed effectively in the presence of metal powders. Bench-scale flotation experiments conducted using Denver laboratory flotation cell and a 2-inch diameter Microcel flotation column, also demonstrates that the collectorless flotation can be suppressed in the presence of the reactive metals. It has been established that the most important parameters determining the effectiveness of suppressing pyrite flotation by the galvanic coupling technique are the surface area of the galvanic contractors and the solids concentration of the slurry during conditioning.
Book Synopsis Control of Pyrite Surface Chemistry in Physical Coal Cleaning. First Quarterly Progress Report, September 1, 1989--November 30, 1989 by :
Download or read book Control of Pyrite Surface Chemistry in Physical Coal Cleaning. First Quarterly Progress Report, September 1, 1989--November 30, 1989 written by and published by . This book was released on 1990 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: To better understand the flotation behavior of coal pyrite, studies have been initiated to characterize the floatability of coal pyrite and mineral pyrite. The hydrophobicity of coal material pyrite was examined over a range of pH and oxidation times. The results indicate that surface oxidation plays an important role in coal and mineral pyrite hydrophobicity. The hydrophobicity of mineral pyrite decreases with increasing oxidation time (20 min. to 5 hr.) and increasing pH (pH 4.6 to 9.2), with maximum depression occurring at pH 9.2. However, coal pyrite exhibited low floatability, even at the lowest oxidation time, over the entire pH range. X-ray photoelectron spectroscopy (XPS) results suggest the growth of an oxidized iron layer as being responsible for the deterioration in floatability, while a sulfur-containing species present on the sample surfaces may promote floatability. Preliminary studies of the effect of frother indicate an enhancement in the floatability of both coal and mineral pyrite over the entire pH range.
Book Synopsis Control of Pyrite Surface Chemistry in Physical Coal Cleaning. Fifth Quarterly Progress Report, September 1, 1990--November 30, 1990 by :
Download or read book Control of Pyrite Surface Chemistry in Physical Coal Cleaning. Fifth Quarterly Progress Report, September 1, 1990--November 30, 1990 written by and published by . This book was released on 1992 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: The successful separation of pyrite from coal by flotation is dependent to a large extent upon the selectivity of the process, and the use of a pyrite depressant is one of the most important and cost-effective techniques for achieving this. This report evaluates the effects of three factors on the floatability of pyrite. These are (1) the superficial oxidation of pyrite, (2) the contamination of pyrite surfaces by carbonaceous matter, and (3) pulp redox potentials. XPS (x-ray photoelectron spectroscopy) and IR spectrometry have been used to identify surface reaction products. Microflotation, laboratory-scale conventional flotation and microbubble column flotation were used to quantify the effects of these factors. It was found that low (reducing) pulp potentials are effective depressants of pyrite (more so for fresh, unoxidized samples than for oxidized samples), whilst at the same time do not materially affect coal flotation.
Book Synopsis Pyrite Surface Characterization and Control for Advanced Fine Coal Desulfurization Technologies. Ninth Quarterly Technical Progress Report, September 1, 1992-- December 31, 1992 by :
Download or read book Pyrite Surface Characterization and Control for Advanced Fine Coal Desulfurization Technologies. Ninth Quarterly Technical Progress Report, September 1, 1992-- December 31, 1992 written by and published by . This book was released on 1992 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the 9th quarterly technical progress report for the project entitled ''Pyrite surface characterization and control for advanced fine coal desulfurization technologies'', DE-FG22-90PC90295. The work presented in this report was performed from September 1, 1992 to November 31, 1992. The objective of the project is to conduct extensive fundamental studies on the surface chemistry of pyrite oxidation and flotation and to understand how the alteration of the coal-pyrite surface affects the efficiency of pyrite rejection in coal flotation. During this reporting period, the surface oxidation of pyrite in various electrolytes was investigated. It has been demonstrated, for the first time, that borate, a pH buffer and electrolyte used by many previous investigators in studying sulfide mineral oxidation, actively participates in the surface oxidation of pyrite. In borate solutions, the surface oxidation of pyrite is tronly enhanced. The anodic oxidation potential of pyrite is lowered by more than 0.4 volts. The initial reaction of the borate enhanced pyrite oxidation can be described by:FeS2 + B(OH)4{sup =} --> [S2Fe-B(OH)4]{sub surf} + e. This reaction is irreversible and is controlled by the mass-transfer of borate species from the solution to the surface. It has been shown that the above reaction inhibits the adsorption of xanthate on pyrite. Comparative studies have been made with other sulfide minerals. The solution chemistry of the iron-borate systems have been studied to understand the electrochemical results.
Book Synopsis Semiconductor Electrochemistry Coal Pyrite. Quarterly Technical Progress Report, October--December 1994 by :
Download or read book Semiconductor Electrochemistry Coal Pyrite. Quarterly Technical Progress Report, October--December 1994 written by and published by . This book was released on 1995 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pyrite dissolution in acidic solution was found to involve both electrochemical oxidation and chemical decomposition. The mechanism of chemical decomposition of pyrite in acidic solution may involve surface complexation of hydrogen ions. The anodic current of pyrite was relatively small in non-aqueous solution (acetonitrile) compared with that in aqueous solution. The implication is that the direct reaction of holes with S22− in the pyrite lattice was not significant and that the dissolution of pyrite required the presence of water. The anodic dissolution product was elemental sulfur which was detected by X-ray diffraction.
Book Synopsis Mechanisms of Pyrite Oxidation to Non-slagging Species. Quarterly Report, April 1, 1995--June 30, 1995 by :
Download or read book Mechanisms of Pyrite Oxidation to Non-slagging Species. Quarterly Report, April 1, 1995--June 30, 1995 written by and published by . This book was released on 1995 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: This document is the fourth quarterly status report on a project that is conducted at the High Temperature Gasdynamics Laboratory at Stanford University, Stanford, California and is concerned with enhancing the transformation of iron pyrite to non-slagging species during staged, low-NO(subscript x) pulverized coal (P.C.) combustion. The research project is intended to advance PETC's efforts to improve our technical understanding of the high-temperature chemical and physical processes involved in the utilization of coal. The work focuses on the mechanistic description and rate quantification of the effects of fuel properties and combustion environment on the oxidation of iron pyrite to form the non-slagging species magnetite. The knowledge gained from this work is intended to be incorporated into numerical codes that can be used to formulate anti-slagging strategies involving minimal disturbance of coal combustor performance. This project is to be performed over the three-year period from September 1994 to August 1997. The project aims to identify the mechanisms of pyrite combustion and to quantify their effects, in order to formulate a general rate expression for the combustion of pyrite that accounts for coal properties as well as furnace conditions.
Book Synopsis Oxidation of Coal and Coal Pyrite Mechanisms and Influence on Surface Characteristics. Technical Progress Report, September 30, 1992 by :
Download or read book Oxidation of Coal and Coal Pyrite Mechanisms and Influence on Surface Characteristics. Technical Progress Report, September 30, 1992 written by and published by . This book was released on 1992 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this research is to develop a mechanistic understanding of the oxidation of coal and coal pyrite, and to correlate the intrinsic physical and chemical properties of these minerals, along with changes resulting from oxidation, with those surface properties that influence the behavior in physical cleaning processes. The results will provide fundamental insight into oxidation, in terms of the bulk and surface chemistry, the microstructure, and the semiconductor properties of the pyrite. During the eighth quarter, wet chemical and dry oxidation tests were done on Upper Freeport coal from the Troutville {number_sign}2 Mine, Clearfield County, Pennsylvania. In addition electrochemical experiments were done on electrodes prepared from Upper Freeport coal pyrite and Pittsburgh coal pyrite samples provided by the US Bureau of Mines, Pittsburgh Research Center, Pennsylvania.
Book Synopsis Oxidation of Coal and Coal Pyrite Mechanisms and Influence on Surface Characteristics. Technical Progress Report, December 1, 1993--May 31, 1994 by :
Download or read book Oxidation of Coal and Coal Pyrite Mechanisms and Influence on Surface Characteristics. Technical Progress Report, December 1, 1993--May 31, 1994 written by and published by . This book was released on 1994 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this research is to develop a mechanistic understanding of the oxidation of coal and coal pyrite, and to correlate the intrinsic physical and chemical properties of these minerals, along with changes resulting from oxidation, with those surface properties that influence the behavior in physical cleaning processes. The results will provide fundamental insight into oxidation, in term of the bulk and surface chemistry, the microstructure, and the semiconductor properties of the pyrite. During the fourteenth and fifteenth quarters, flotation tests were done on Upper Freeport coal from the Troutvill {number_sign}2 Mine, Clearfield County, Pennsylvania and on coal samples from the Pennsylvania State Coal Bank. The influence of electrode potential on the surface properties of coal pyrite was tested using contact angle measurements on polarized Pittsburgh coal pyrite electrode.
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