ASTM D5003 Standard Test Method for Hardgrove Grindability Index (HGI) of Petroleum Coke
4. Summary of Test Method
4.1 The sample of petroleum coke is reduced (crushed) to produce a high yield of particles passing a 1.19 mm (No. 16) sieve and retained on a 0.59 mm (No. 30) sieve. These particles are reduced in the hardgrove grindability machine according to Test Method D409. The quantity of particles retained on a 0.074 mm (No. 200) sieve is used to calculate the HGI of the sample.
5. Significance and Use
5.1 The HGI is used to predict the ranking ofraw petroleum cokes or calcined petroleum cokes in industrial size mills used for crushing operations. The rankings are based on energy required and feed rate or both.
5.2 The HGI is also used to select raw petroleum cokes and coals that are compatible with each other when milled together in a blend so that segregation of the blend does not occur during particle size reduction.
6. Hazards
6.1 Calcined petroleum coke is generally coated with a dedusting agent to decrease the occurrence and the quantity of dust during subsequent transporting of the calcined petroleum coke. The dedusting agent is an oil or suitable material. When a dedusting agent is present and is not removed prior to the determination of HGI there can be interference in the sieving step to measure the portions retained on and passing a 0.074 mm (No. 200) sieve. Removal of the dedusting agent after calcined petroleum coke is reduced to pass the 4.76 mm (No. 4) sieve and before stage crushing to pass the 1.19 mm (No. 16) sieve is required. Suitable solvents for oil removal are dichloromethane, dichloroethane and toluene. (Warning - See the appropriate materials safety data sheet.) The solvent used must be removed prior to the reduction to pass the 1.19 mm (No. 16) sieve. Heating to 10°C above the boiling point of the solvent used or application of vacuum is satisfactory for the removal.
