ASTM D6791 Test Method for Determination of Grain Stability of Calcined Petroleum Coke
4. Summary of Test Method
4.1 A representative sample of calcined petroleum coke is dried and screened to a 4 mm to 8 mm fraction. The resultant sample is weighed so that two separate portions of 100.0 g +/- 0.5 g mass are obtained. The samples are place into the laboratory mill and ground for a specified period of time. After grinding the sample is screened and the mass of the + 4 mm material is determined. The grain stability is the percent of the original material remaining on the + 4 mm sieve.
5. Significance and Use
5.1 The grain stability of calcined petroleum coke determines the resistance to breakdown of + 4 mm particles used in the manufacture of carbon anodes for use in the reduction process of aluminum.
5.2 Calcined petroleum cokes have to be relatively easy to grind for fines production but strong enough to withstand forming pressures and thermal stresses occurring when the anodes are used in the reduction process.
6. Interferences
6.1 No material normally applied to the calcined petroleum coke is found to cause analytical interference with this procedure.
