Standard Item Particle Size Bulk density apparent density sphericity. Acid concentration Breakage Rate Medium density (69 Mpa) 2040 (mesh) 1.731.80 3.253.35 0.9 ≤6 ≤5 Medium density (86 Mpa) 1.3050 (mesh) 2.2040 (mesh) 3.1630 (mesh) 4.1620 (mesh) 1.731.80 3.23.3 0.9 ≤6 ≤5 Medium density (86 Mpa) 4070 (mesh) 1.731.80 3.23.3 0.9 ≤6 ≤5