Chemical Coal Cleaning Using Selective Oxidation

Chemical Coal Cleaning Using Selective Oxidation
Author:
Publisher:
Total Pages: 28
Release: 1991
Genre:
ISBN:

The primary objective of this study is to investigate the removal of both mineral and organic sulfur from Illinois coals using low temperature selective oxidation. This overall objective is to develop new methods for either physical/chemical or physical/microbial cleaning of Illinois coal. Innovative approaches to achieve deep cleaned products, containing both ash and sulfur contents less than 0.5 percent, will be considered. Experiments focus on developing cost-effective methods for the removal of organic sulfur and finely disseminated mineral impurities, especially fine pyrite particles, from coal. Rates and mechanisms for organic sulfur removal will be studied. Chemical reagent recycling and/or reagent wastes will be studied. Chemical reagent recycling and/or reagent wastes handling are included. Bench scale studies are performed.

Chemical Coal Cleaning Using Selective Oxidation. Final Technical Report, September 1, 1990--August 31, 1991

Chemical Coal Cleaning Using Selective Oxidation. Final Technical Report, September 1, 1990--August 31, 1991
Author:
Publisher:
Total Pages: 28
Release: 1991
Genre:
ISBN:

The primary objective of this study is to investigate the removal of both mineral and organic sulfur from Illinois coals using low temperature selective oxidation. This overall objective is to develop new methods for either physical/chemical or physical/microbial cleaning of Illinois coal. Innovative approaches to achieve deep cleaned products, containing both ash and sulfur contents less than 0.5 percent, will be considered. Experiments focus on developing cost-effective methods for the removal of organic sulfur and finely disseminated mineral impurities, especially fine pyrite particles, from coal. Rates and mechanisms for organic sulfur removal will be studied. Chemical reagent recycling and/or reagent wastes will be studied. Chemical reagent recycling and/or reagent wastes handling are included. Bench scale studies are performed.

Mild Pyrolysis of Selectively Oxidized Coals. Technical Report, September 1, 1991--August 31, 1992

Mild Pyrolysis of Selectively Oxidized Coals. Technical Report, September 1, 1991--August 31, 1992
Author:
Publisher:
Total Pages: 34
Release: 1992
Genre:
ISBN:

The primary objective of this study was to evaluate selective oxidation as a pretreatment for the enhanced desulfurization of Illinois Basin coals using a variety of mild thermal/chemical processes. Both an Illinois No. 6 and an Indiana No. 5 coal were selectively oxidized with peroxyacetic acid in the pretreatment step. The products were then treated with many hydroxide and carbonate bases using either water, methanol or ethanol as the solvent system. Other reaction variables investigated include reaction temperature, reaction time, pyrolysis pressure, particle size of the coal and the level of oxidation in the pretreatment step. Throughout the study the selectively oxidized coals were compared to unoxidized control coals. Model compounds were also studied. The results of these studies overwhelmingly show that selective oxidation with peroxyacetic acid significantly enhances the level of desulfurization obtained with subsequent chemical/thermal treatments. Indeed, every process investigated, including simple pyrolysis experiments, showed sulfur removal in the pretreatment step and the subsequent step to be substantially additive. In addition, considerable enhancement in the reactivity of the sulfur in the coal was obtained by the selective oxidation pretreatment. Sulfur contents lower than 0.25% were obtained for selectively oxidized coals. This represents an overall sulfur reduction of around 95%. This is beyond the level required for compliance with Clean Air Act legislation. No unoxidized coal, regardless of the desulfurization treatment, approached this level of sulfur removal.

Mild Pyrolysis of Selectively Oxidized Coals

Mild Pyrolysis of Selectively Oxidized Coals
Author:
Publisher:
Total Pages: 20
Release: 1991
Genre:
ISBN:

The primary objective of this study is to investigate the removal organic sulfur from selectively oxidized Illinois coals using mild thermal/chemical processes. Work completed this quarter includes the investigation of the mild pyrolysis of unoxidized coals plus a selection of selectively oxidized coals. In addition the effect of particle size and extent of oxidation on pyrolysis was investigated. Some preliminary data concerning pyrolysis under vacuum and ambient pressure was also obtained. Work completed this quarter supports the following conclusions: (1) Desulfurization of unoxidized coals increases with increasing pyrolysis temperature and correlates with the loss of volatile matter. (2) Particle size did not influence the extent of desulfurization significantly. (3) Removing pyrite prior to pyrolysis helps to achieve a lower sulfur product beyond that expected from the removal of pyrite alone. (4) The extent of selective oxidation in teh pretreatment step did not effect the level of desulfurization obtained by pyrolysis alone. However this factor was important in the desulfurization obtained with supercritical methanol (SCM)/base. (5) Up to 84% of the sulfur has been removed from the IBC 101 coal by combining selective oxidation and SCM/base reactions. (6) Evidence for regressive reactions between volatilized sulfur compounds and partially desulfurized products was obtained by studying how changes in pyrolysis pressure effected the product sulfur content.

Mild Pyrolysis of Selectively Oxidized Coals. [Quarterly] Technical Report, December 1, 1991--February 29, 1992

Mild Pyrolysis of Selectively Oxidized Coals. [Quarterly] Technical Report, December 1, 1991--February 29, 1992
Author:
Publisher:
Total Pages: 23
Release: 1992
Genre:
ISBN:

The primary objective of this study is to investigate the removal organic sulfur from selectively oxidized Illinois coals using mild thermal/chemical processes. Work completed this quarter primarily concerned establishing the level of selective oxidation required for successful desulfurization in subsequent treatments. Many desulfurization reactions were performed on pretreated as well as unoxidized coal. The results obtained support the following new conclusions: (1) The extent of selective oxidation in the pretreatment step does not effect the level of desulfurization obtained by pyrolysis alone. However this factor was important in the desulfurization obtained with supercritical methanol (SCM)/base. (2) Up to 84% of the sulfur in the IBC 106 coal and 86% of the sulfur in the IBC 106 coal has been removed by combining selective oxidation and SCM/base reactions. (3) Most desulfurizations at 250°C did not produce significant levels of desulfurization. However as the temperature was increased levels of desulfurization increased considerably. (4) Although aqueous base was successful in removing sulfur from both pretreated and untreated samples, the most pronounced desulfurizations were obtained for the untreated samples. This is explained primarily by the dissolution of pyrite in the untreated samples. (5) The best desulfurizations involved SCM and base. Possible synergistic interactions between the methanol and the base are suspected. (6) Overall, selective oxidation pretreatment always led to a lower sulfur product. The severity of desulfurization is reduced by selective oxidation pretreatment.

Mild Pyrolysis of Selectively Oxidized Coals. [Quarterly] Technical Report, March 1, 1992--May 31, 1992

Mild Pyrolysis of Selectively Oxidized Coals. [Quarterly] Technical Report, March 1, 1992--May 31, 1992
Author:
Publisher:
Total Pages: 24
Release: 1992
Genre:
ISBN:

The primary objective of this study is to investigate the removal organic sulfur from selectively oxidized Illinois coals using mild thermal/chemical processes. Work completed this quarter primarily concerned the investigation of the desulfurization of the selectively oxidized coals using aqueous or alcoholic base mixtures. Model compound studies were initiated. Results were: Levels of desulfurization obtained in this study are at, or very close to, the 90% removal levels required for these coals to be in compliance with the Clean Air Act legislation; Up to 89.4% of the sulfur in the IBC 101 coal and 88.9% of the sulfur in the IBC 106 coal has been removed by combining selective oxidation and alcoholic/base reactions; Overall, selective oxidation pretreatment always led to a lower sulfur product than the untreated sample; Substantial enhancement in the reactivity of the sulfur in the coal has been achieved by the selective oxidation pretreatment; The highest levels of desulfurization obtained so far all involve bases as additives; The water/Na2CO3 combination, was superior than any of the aqueous hydroxide bases. Possible synergistic interactions between the alcohol and the base are suspected. Over 70% of the sulfur in the IBC 101 coal can be removed by performing vacuum pyrolysis on the selectively oxidized coal. Lower sulfur contents are obtained by lowing the pyrolysis pressure.