Hardgrove Grindability Index (HGI)

The Hardgrove Grindability Index (HGI) is a measure of coal’s resistance to crushing. Grinding studies, and the resulting HGI, allow many different types of coal users to evaluate how coals will perform in their mills, allowing them to estimate grinding power requirements and throughput capacities.

SGS is a world leader in coal and coke testing services. Our coal testing procedures are completed globally by technical experts in state-of-the-art facilities. SGS testing results are returned in a timely manner and comply with ASTM, ISO and other international standards.

HGI is determined through a multi-step procedure:

1. A 50-gram sample of prepared coal that is uniform in size is placed inside a grinding unit
2. The unit undergoes a standard number of revolutions under a specified pressure
3. Steel balls within the unit crush the coal sample
4. The coal fines are sorted and the quantity of coal less than a specified size is recorded and converted into a Hardgrove Grindability Index (HGI) value

Typical resulting HGI values lie between 30 (increased resistance to pulverization) and 100 (more easily pulverized).

Experienced SGS technicians ensure your HGI testing is completed promptly and in accordance with global industry standards. Rely on the SGS global team for the results that allow you to make accurate estimations of the power requirements and throughput capacities in your facilities, leading to optimized plant operation and an improved bottom line.