ASTM D409/D409M-16 PDF Download

The relative grindability or ease of pulverization of coals in contrast to predetermined requirements is assessed using the ASTM D409/D409M-16 standard. A prepared and measured coal sample is ground in a small pulverizer to a predetermined energy input, and the crushed output is sieved to determine its consistency in size. The Hardgrove Grindability Index (HGI), which offers a measurement of the coal's grindability, is computed using the resulting size.

This test method's objective is to assess the coal's grinding or pulverizing properties, which may have an impact on a number of procedures, including combustion, coke-making, liquefaction, and gasification. It enables the evaluation of the energy input or yield necessary in various processes, offering useful data for coal utilization.

It is important to keep in mind that some coals, especially high-volatile bituminous, subbituminous, and lignite coals, could experience physical changes as moisture is released during handling and processing. Depending on drying conditions and moisture levels, these alterations may have an impact on grindability characteristics and lead to varied grindability indices. The repeatability and reproducibility described in the test procedure might not be applicable to these kinds of coals as a result.