Hardgrove Grindability

Other Tests. The so-called tumbler tests are usually used for testing material like coke, coal, iron ore pellets or tablets. They can be divided into drum tests and ball mill type tests. The latter type is used to derive both the Hardgrove Index and the Bond s Work Index, which are often used to classify the material friability as described in Sec. 3. They are generally more suited to coarse material. The Hardgrove Grindability test requires an initial size range form 595 to 1190 microns. 

Philip L. Walker Hardgrove grindability data for many Pennsylvania anthracites have been determined and reported on in the Proceedings of the 1956 Anthracite Conference held at Pennsylvania State University. 

Other important chemical and physical tests performed to characterize coal include (I) Heating value (Btu content) (2) sulfur forms (31 ash fusibility temperatures (4) ash analysis (5) trace elements (6) free swelling index and (7) hardgrove grindability. 

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. 

Grindability index number that indicates the ease of pulverizing a coal in comparison to a reference coal. This index is helpful in estimating mill capacity. The two most common methods for determining this index are the Hardgrove grindability method and ball mill grindability method. Coals with a low index are more difficult to pulverize. 

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

Standard tests consisted of proximate, ultimate, higher heating value, ash composition, ash fusibility temperatures, Hardgrove grindability, and screen analyses. Special bench scale characterization tests consisted of micro-proximate analysis and micro-ultimate analysis (C, H, N) micro-proximate and micro-ultimate analyses were performed on particulate samples collected from varying stages of combustion in the DTFS and CMHF. In addition, selected samples of SRC and chars from partial combustion or pyrolysis of the SRC were submitted for Thermo-Gravimetric analyses. 

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.)... 

Gross calorific value Hardgrove grindability Majcr and minor elements Proximate analysis Reflectance of organic matter Total moisture Trace elements Ultimate analysis Volatile matta-Maceral analysis... 

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