The design of a feeding or pneumatic conveying system is heavily influenced by a bulk solid’s particle shape, size (aspect ratio) and particle size distribution as well as the particle’s roughness, hardness (abrasiveness), and density. In the case of calcium carbonate these characteristics vary widely depending on the source and production process for the individual samples.
The sieve analysis below illustrates the difference in particle shape, particle size and particle size distribution for two samples of calcium carbonate. The large number of particle interactions makes it impossible to establish a clear correlation between filler’s properties at the particle level and its flow behavior as a bulk solid.
As a consequence, pneumatic conveying systems cannot be purchased “off-the-shelf” and must be engineered for each situation individually. Both systems engineering and equipment selection are affected by differences in a bulk solid’s characteristics. Laboratory tests are often necessary to help determine a material’s properties and behavior. A pneumatic conveying system generally consists of five basic components: a gas motive, a conveying line, a dispensing device, a material-gas separator and controls.