Single Coal Accreditation Program (SCAP)
Six (6) mounted coal blocks ground to 1 mm size in which production of fine particles is minimized must be analysed for entering the program. Successive analysis consist of two ground un-mounted samples which should be prepared at the analyst’s laboratory. ISO 7404-2 (2009) to be followed for sample preparation.
Two parameters are separately evaluated to determine which petrographer is accredited in these two procedures:
- vitrinite maceral group percentage, on a minerals-free basis (ISO 7404-3; 2009)
- mean vitrinite random reflectance percentage (ISO 7404-5; 2009), measured on Telovitrinite sub-Group macerals (ICCP, 1998).
Note: If a procedure sensitive to segregation is used for sample preparation, the analysis should be performed following traverse perpendicular to segregation and counts over 500 for maceral analysis and over 100 for vitrinite reflectance measurements should be recorded until finalizing the last traverse.
At the conclusion of the exercise, the results from all participating petrographers are pooled. A statistical evaluation for each of the two procedures identifies those petrographers whose results do not fall within acceptable limits of departure from the group mean or that report results which are consistently higher or lower than the group mean (see Statistical Evaluation in Detail).
Petrographers who are not accredited in both reflectance and maceral group analyses, or are accredited in only one (1) analysis (that is, either maceral group or reflectance), will have to perform six (6) complete analyses for either both parameters or the parameter in which they were not accredited. These six sets of analyses will then form the petrographer’s new data file that will be statistically assessed and to which all subsequent analyses are added and evaluated.
International Committee for Coal and Organic Petrology, (ICCP), 1998. The new vitrinite classification (ICCP System 1994). Fuel 77, 349–358.
ISO 7404-2, 2009. Methods for the Petrographic Analysis of Coals — Part 2: Methods of Preparing Coal Samples. International Organization for Standardization, Geneva, Switzerland. 12 pp.
ISO 7404-3, 2009. Methods for the Petrographic Analysis of Coals—Part 3: Method of Determining Maceral Group Composition. International Organization for Standardization, Geneva, Switzerland. 7 pp.
ISO 7404-5, 2009. Methods for the Petrographic Analysis of Coal—Part 5: Methods of Determining Microscopically the Reflectance of Vitrinite. International Organization for Standardization, Geneva, Switzerland. 14 pp.