Contaminants from Coal Gasification

Complex Mixture Extraction. Analytical SFE can also be used for complex mixture sample preparation. Typical examples using hazardous waste samples are described below. Sample A was a soil boring contaminated with coal gasification residuals and sample B was from a waste stream from a treatment facility. The major objective of these studies was to compare the extraction abilities (e.g., amount of material extracted) of three different fluid systems using approximately four-gram aliquots of the samples. The specific fluid systems, the extraction conditions, and the percentage of the total mass of material extracted from each sample are listed in Table II. 

Tablell-1 Typical Contaminant Levels Obtained from Selected Coal Gasification... 

Exposure of the general population to 2-hexanone is not likely to be high. However, persons living near hazardous waste sites or wood pulping, coal-gasification, or oil-shale processing plants may be exposed to 2-hexanone in contaminated environmental media. In the past, occupational exposures to 2-hexanone resulted from its manufacture and use. However, since 2-hexanone is not currently manufactured or used commercially in the United States, occupational exposures related to these activities are no longer of special concern. 

According to the vendor, landfarming was used to treat 10 yd of soil contaminated with PAH from a coal gasification plant in Connecticut. The cost of this pilot-scale demonstration was approximately 80/yd (D213718, p. 6). 

Field demonstration of an aerated soil cell was conducted with soil contaminated by PAH originating from a coal gasification plant (Taddeo et al., 1989). After 78 days of compost treatment, total PAH concentrations were reduced from 6330 to 370 mg/kg compost. However, 5-ring PAHs including benzo[ pyrene were not degraded within this time period. 

Methanol, also called methyl alcohol and once commonly know as wood alcohol, is a clear, volatile liquid mp, -98°C bp, 65°C). Until the early 1900s, the major commercial source of methanol was the destructive distillation (pyrolysis) of wood, a process that yields a product contaminated with allyl alcohol, acetone, and acetic acid. Now methanol is synthesized by the following reaction of hydrogen gas and carbon monoxide, both readily obtained from natural gas or coal gasification ... 

Gas-solid noncatalytic reactions are encountered in a broad range of industrial processes, including coal combustion and gasification, mineral processing, the capture of contaminants from gas streams, and the regeneration of coked catalysts. In applications such as combustion and gasification, the solid phase disappears as the reaction proceeds, while in others such as the capture of sulfur from gas streams, the solid reactant is converted into a solid product. 

Many of these steps are made necessary by the presence of naphtha and other troublesome contaminants in the gas stream and are not normally included in plants that treat gas streams derived from sources other than the Lurgi coal gasification process. 

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