Hardgrove grindability index

State County Bed Mine Hardgrove Grindability Index... 

FIGURE 8.2 Calibration chart for the Hardgrove grindability index. (From ASTM, 2004.)... 

FIGURE 8.3 Variation of Hardgrove grindability index with volatile matter. (From Berkowitz, 1979, p. 91.)... 

ASTM D-5003. Standard Test Method for the Hardgrove Grindability Index (HGI) of Petroleum Coke. 

Hardgrove grindability index weight percent of coal retained on a No. 200 sieve after treatment as specified in ASTM D-409. 

In the test method (ASTM D-5003), the coke sample is crushed to produce a high yield of particles passing a No. 16 sieve and retained on a No. 30 sieve. These particles are reduced in the Hardgrove grindabiUty machine according to the test method for coal (ASTM D-409). The quantity of particles retained on a No. 200 sieve is used to calculate the Hardgrove grindability index of the sample. Both this test method and the test method for coal (ASTM D-409) produce the same results on petroleum coke samples. 

Hardgrove grindability index Measure of the ease by which the size of a coal can be reduced. Values decrease with increasing resistance to grinding. 

The hardgrove grindability index (HGT). This indicates the ease with which the coal can be ground to fine powder. HGI is the test most directly related to the maceral and maceral group composition but is also dependent on rank and mineral content. 

FIGURE 6.4 Relationship of specific energy to hardgrove grindability index for two size reduction devices. (From Meyers, R.A., Ed., Coal Handbook, Marcel Dekker, New York, 1981, p. 177.)... 

The Hardgrove Grindability Index was originally developed by Babcock and Wilcox to measure the relative ease of pulverizing coal. This ASTM D409-71 method has since been employed for characterizing other particles as well. The method processes 50 g of air-dried particles screened to a size of 16 x 30 mesh (1180 X 600 pm) in a small ball-and-race mill for 60 revolutions. The amount of material (1 200) passing the 200 mesh (75 pm) screen is then measured. The result is then compared with a standard index to arrive at the HGI or the HGI is calculated from the equation... 

Petroleum coking can be varied to impact petroleum coke fuel properties and quality, as has been shown by the development of the OptiFuel process of Environmental Energy Enterprises. This variability includes volatility, type of volatile matter, and Hardgrove Grindability Index. 

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