Bulk materials with particles exceeding this diameter are commonly scalped at 4 millimetres before testing.

Due to its small size, this cell limits the maximum testable particle diameter, which may not exceed one fifth of the cell height. One of the most common methods is described in detail in ASTM D6683-19 and typically uses a small cell of 21-millimetre height by 64-millimetre diameter (approximately a 1:3 aspect ratio). There are several methods for measuring bulk density and compressibility, and it is important to understand the differences to ensure that the most appropriate method will be used for each application. Figure 3 – Example of compressibility for a given ore at three moisture contents.Ĭharacterising bulk density and compressibility: The graph in Figure 3 highlights that moisture content might greatly influence compressibility depending on the material. Some applications require explicit knowledge of the compressibility, others, including mass estimation, require knowledge of the relationship between bulk density and consolidation load. Measuring the bulk density at increasing consolidation allows for this relationship to be established (Figure 3). Therefore, a bulk material may exhibit different bulk densities depending on the consolidation load.Ĭompressibility characterises the change in bulk density with increasing consolidation stress. Consolidating the material might affect the air voids and the volume occupied by the particles depending on how compressible the solid is. In simple terms, bulk density can be determined as:Ĭompressibility, on the other hand, concerns the consolidation states of the bulk material. Figure 1 – Representation of bulk density. They are normally used for surge capacity either to store material that will be processed later or to account for differences in throughputs along the handling chain.īulk density: definition, characterisation and applicationsīulk density is the relationship between mass and the volume occupied by the mass of all constituents: bulk solid particles, moisture and air, as illustrated in Figure 1. Stockpiles are some of the most common means of storing large quantities of bulk materials in industry sectors including mining and steelmaking plants, as well as in the fertiliser industry, ports and others. Jens Plinke, Consulting Engineer, and Priscilla Freire, Business Development Engineer at TUNRA Bulk Solids explain important considerations when determining bulk density, the difference between bulk density and compressibility, the development of improved testing methods and application to stockpile mass estimation for inventory purposes.

Gravel stockpile calculator