Hardgrove Grindability Index (HGI) & Standard Reference Materials (HGI-SRM)

The Hardgrove Grindability Index Standard Reference Material (HGI-SRM) is a sample of coal used to calibrate instruments that are designed to determine the ease with which coal can be pulverized. The HGI value provides information for determining grinding power consumption and pulverizer capacities.

The HGI-SRM is prepared in a series of steps over several days. All procedures conform to American Society for Testing and Materials (ASTM) standard methods (Appendix A). Coal is purchased according to specifications. The Hardgrove Grindability Index is calculated on four splits (or portions), two each taken from the two reserved cans. The results are averaged to give the index for the entire lot. Cans of standard reference sample are shipped to customers upon request, along with a questionnaire designed by ASTM to obtain data on the quality of the sample. The data obtained on the questionnaire is used by ASTM to perform detailed statistical analysis of HGI-SRM production.

The HGI-SRM come in sets of four, containing four standards of approximate HGI values 40, 60, 80, and 100. Each set costs $1,200 for domestic orders and $1,400 for foreign orders to help cover the manufacturing and shipping costs.

For more information, download the HGI-SRM Order Form and Data Sheet.