No abstract

Coal has often been described as one of the most difficult materials to sample because of its inherent heterogeneity. Therefore, fundamental to any coal assessment is an understanding of the impacts of the geological heterogeneity on coal quality variability for a given area. Since the mid-1970s, the U.S. Geological Survey (USGS) has maintained a coal quality database of national scope named USCHEM, which currently contains data for over 13,000 samples. A subset of the USCHEM database called COALQUAL Version 1.3 was initially published in 1994. Version 3.0 of the COALQUAL database represents a major editing effort to resolve some of the DOS software limitations used by earlier versions of the database. Because of database size limits during the development of COALQUAL Version 1.3, many analyses of individual bench samples were merged into whole coal bed averages. The methodology for making these composite intervals was not consistent. Size limits also restricted the amount of georeferencing information and forced removal of qualifier notations such as "less than detection limit" (<) information, which can cause problems in using the data. A review of the original data sheets revealed that COALQUAL Version 2.0 was missing information, which was needed for a complete understanding of a coal section. Another important database issue to resolve was the USGS "remnant moisture" problem. Prior to 1998, tests for remnant moisture (as-determined moisture in the sample at the time of analysis) were not performed on any USGS major, minor, or trace-element coal analyses. Without the remnant moisture, it is impossible to convert the analyses to a usable basis (as-received, dry, etc.). Based on remnant moisture analyses of hundreds of samples of different ranks and known residual moisture reported (moisture reported at the time of the ultimate and proximate analysis) after 1998, it was possible to develop a method to provide reasonable estimates of remnant moisture for older data to make it more useful in COALQUAL Version 3.0. In addition, the COALQUAL Version 3.0 database is improved by (1) adding qualifiers, including statistical programming to deal with the qualifiers; (2) clarifying the sample compositing problems; and (3) adding associated samples (discussed in more detail in report). Version 3.0 of COALQUAL also represents the first attempt to incorporate data verification by mathematically crosschecking certain analytical parameters. Finally, a new database system was designed and implemented to replace the outdated DOS program used in earlier versions of the database. The COALQUAL Version 3.0 database is located at http://ncrdspublic.er.usgs.gov/coalqual/. Parameter name Description Ash Softening Ash softening temperature in degrees Fahrenheit as determined by ASTM method D1857 in reducing atmosphere (ASTM, 2014). This parameter was ASHSOF in COALQUAL Version 1.3 and Version 2.0. *Ash Softening Q* Qualifier for Ash Softening. Ash Fluid Ash fluid temperature in degrees Fahrenheit as determined by ASTM method D1857 in re...

This list contains the results of measurements made during 1965 and 1966. Samples are counted in the form of acetylene gas, as previously, and ages computed on the basis of the Libby half-life, 5568 ± 30 yr. The error listed is always larger than the one-sigma statistical counting error commonly used, takes into account known uncertainty laboratory factors, but does not include external (field or atmospheric) variations.

No abstract

This list contains the results of measurements made during 1963 and 1964. Samples are counted in the form of acetylene gas, as previously, and ages computed using the Libby half-life of 5568 ± 30 yr. The error listed is always larger than the one-sigma statistical counting error commonly used, takes into account known uncertainty laboratory factors, but does not include external (field or atmospheric) variations.