ASTM D287

General

The grain stability of calcined petroleuni 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. 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. This test method covers a laboratory vibration mill for the determination of grain stability of calcined coke for the manufacture of carbon products used in aluminum smelting. Calcined coke with poor mechanical strength may become degraded during mixing. Poor grain stability will affect the grain size and may result in poor quality of baked blocks.

Precision

• Repeatability:       2%
• Reproducibility:   3%

Test

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±0.5 g mass are obtained. The samples are placed into the laboratory mill and ground for a specific 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 materials remaining on the +4 mm sieve.

How D287 and ASTM D1298 compare

   ASTM D287 → reports API gravity only

   ASTM D1298 → reports density, specific gravity, or API gravity

   D287 is more API-focused, D1298 is more general-purpose

ASTM D1298 vs ASTM D287