Sulfur from coal , removal

The developed process aimed for the removal of iron and sulfur from coal. While several patents for microbial removal of pyrite from coal exist, this one is unique because of the microbial mixture developed by the group for this purpose, which is partially... 

Ledgemont A process for removing sulfur from coal by an oxidative leach with lime and ammonia. Developed by Hydrocarbon Research. 

The goal of beneficiation is to remove as much sulfur from a fuel as possible before it is ever burned. When burned, fuel with lower sulfur content will produce less sulfur dioxide. Beneficiation is usually accomplished by a physical process that separates one form of sulfur, pyritic sulfur, from coal. Pyritic sulfur consists of sulfur minerals (primarily sulfides) that are not chemically bonded to coal in any way. The name is taken from the most common form of mineral sulfur usually found in coal, pyrite, or iron sulfide (FeS2). 

A process designed to remove organic sulfur from coal prior to combustion involves the following reactions ... 

Meyers, R. A. Hart, W. D. "Chemical Removal of Organic Sulfur from Coal " Synp. on Removal of Heteroatoms from Fuel, ACS Meeting, Houston, TX, March 23-28, 1980. 

TRW, "Laboratory Study for Removal of Organic Sulfur from Coal " Final Report to U.S. DOE, DE-AC-80PC30141, July 1, 1981. 

From this, it can be seen that the amount of KOH within the hydroxide mixture would probably be critical in removing organo-sulfur from coal. While the particular role of KOH has not been determined, evidence from the literature has shown that the size of the cation may be important in stabilizing intermediate carbanions. Wallace et al. (J ) conducted a series of base- catalyzed, beta-elimination reactions with isopropyl sulfide and measured the amount of olefin production. The proposed mechanism involved initial abstraction of a proton by the t-butoxide base, and formation of a carbanion, with subsequent elimination of the sulfur moiety (which can be considered a good leaving group) to form the olefin (Equation 5). 

Removal of Organic Sulfur from Coal by Reaction with Supercritical Alcohols... 

Growing concern over environmental effects of acid rain has resulted in increased Interest in development of pre-combustion removal of sulfur from coal. Physical coal cleaning processes are effective for pyritic sulfur removal but do little to reduce the organic sulfur content of coal This paper reports the removal of organic sulfur from coal, employing ethyl or methyl alcohols as the solvent/ reactant. The process is based on the observation that, under supercritical conditions, reactions occur that selectively remove organic sulfur from the coal matrix. 

Preparative methods, both large- and small-scale, are used widely for the simple purpose of removing low-level contaminants from products of value (e.g., sulfur from coal). There is major emphasis now on developing better methods to remove pollutants from air and water. 

As the removal of sulfur from coal prior to combustion acquires more importance in order to meet evermore stringent antipollution regulations, research on the development of methods for the cleaning of coal continues to expand. Reviews are available which describe the various methods for... 

In our work, the removal of organic sulfur from coal was followed by the ASTM procedure. In addition, the fate of iron and sulfur was assessed by a series of extraction experiments with analysis of the solid residues and the liquid extracts by conventional chemical methods. Finally, an instrumental method based on electron microprobe X-ray analysis was used for the direct determination of organic sulfur in the organic coal matrix (18, 19). The analytical results from the different... 

Thus the difficulties in evaluating the removal of organic sulfur from coal are not only due to differences in... 

Follow the process as this power plant removes the sulfur from coal to reduce air pollution. Where is the sulfur found at the end of the process ... 

Chemical Removal of Pyritic Sulfur from Coal... 

A new approach for the chemical removal of pyritic sulfur from coal is described. The process is based on the discovery that aqueous ferric salts selectively oxidize the pyritic sulfur in coal to chemical forms which can be removed by vaporiza-tion, steam, or solvent extraction. Data for removal of the pyritic sulfur from four major coals (Lower Kittanning, Illu nois No. 5, Herrin No. 6 and Pittsburgh) are presented together with a discussion of the process chemistry. The effect of variables, such as coal particle size, acid and iron concern tration, reaction time, and temperature are discussed. The results show that near complete removal of pyritic sulfur can be obtained under mild conditions, resulting in a reduction of the total sulfur content of the coals from 40 to 80%, depending on the original pyritic sulfur content. 

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