Abstract: Coal Sample Preservation in Foil Multilaminate Bags

GLICK, DAVID C., GARETH D. MITCHELL, and ALAN DAVIS

Since 1989, coal samples newly collected for the Penn State Coal Sample Bank have been sealed for long-term storage under argon in heat-sealed bags composed of aluminum foil and polyethylene multilaminate. Since 1993, all samples have been refrigerated to retard chemical change.

The samples have been analyzed annually for moisture, sulfur forms, calorific value, Gieseler fluidity (on samples of appropriate rank) and gaseous oxygen within the bags. Results show that this storage protocol preserves the initial properties of the samples very well. For seven samples monitored over at least five years, moisture and calorific value show no decrease on average; Gieseler fluid range has decreased only 3 degrees C on average; and the final sulfate sulfur level for every sample is no higher than the initial value.

A separate study was performed on Argonne premium coal samples in original glass ampoules compared to those resealed in multilaminate bags. Gieseler fluidity analyses through time in this study also show that the bags are comparable to glass ampoules over a two-year period.

The bags are available in a variety of sizes, allowing all splits of a sample to be stored in the same container type. They provide a cost-effective method for short- or long-term preservation of moderate quantities of coal samples for research.

AAPG Search and Discovery Article #90939©1997 AAPG Eastern Section and TSOP, Lexington, Kentucky