| Haultain infrasizer | A vertical air elutriator similar to the roller elutriator. |
| homogenising | The rendering of components that were initially separate or varied in nature throughout the volume of a mass, to a compound of uniform composition at a scale of scrutiny that is significant to the application. (See blending and mixing). |
| hot pressing | The compaction of a powder under heat and pressure, to result in sintering of the mass to a strongly bound mass. |
| minimum fluidising velocity | The minimum gas velocity required to fluidise a bed of powder. The value depends mainly upon the particle size and effective particle density. |
| pegging | The conditions which occurs when particles wedge in the apertures of a sieving medium. |
| pellet | An agglomerate of particles produced by specialised techniques, such as pressing. |
| pre-sintering | A heat treatment carried out at a temperature below a final sintering temperature to strengthen a powder compact. |
| pressing | The compaction of a powder under pressure in a mould or die. |
| pressing, cold | (See cold pressing). |
| pressing, hot | (See hot pressing). |
| pressing, warm | (See warm pressing). |
| quiescent bed | A bed of particulates held in a steady, tranquil state of suspended dilatation by the passage of a second phase media. |
| roller elutriator | A vertical air elutriator used for fractionating powder in the size range 5 to 300 microns. |
| roll press | A compacting device that consolidates powder between two contra- rotating rollers under a nip pressure acting on the small gap between the rollers. The rollers may have flat surfaces, to produce flakes, or have mould indentations that form pellets or nodules. |
| scalping | The separation of a small amount of oversize lumps or particles from a bulk material by size classification. |
| settled bed | A stable bed of particulates where particle to particle contact pressure is fully developed and not relieved by internal void pressure or the counter-flow of a fluid. |
| settling bed | A transient condition, where a bed of dilated particles has an increasing density condition and a decreasing void pressure as the media in the interstitial volume at a higher pressure than ambient percolates from the bed, ultimately to allow particle-to-particle contact pressures to develop to those of a fully-settled bed where the void pressure is ambient. |
| shrinkage | The reduction in size of a compact on drying or sintering, expressed as a percentage of the final volume or stated linear dimension. |
| sintering | The bonding of contiguous particles in a mass of powder or a compact by partial fusion at temperatures below the melting point of the particles. |
| spiral flow classifier | A device for fractionating fine particles by moving a fluid stream in which the particles are suspended through a cylindrical vessel from a tangential inlet to a more centrally located outlet. The extend to which centripetal forces on the particles overcome fluid drag is related to the physical characteristics of the individual particles and determines the ability of the particles to exit at specific radially located outlets of the equipment. The division between outlet positions being terms the ‘cut’. |
| tablet | A small compact. |
| trajectory | The path taken by a particle with an initial component of horizontal motion under the influence of gravity and/or prevailing air flow. |
| warm pressing | The compaction of a powder under pressure above room temperature and below sintering temperature. |
| wet scrubbers | A dust collecting system that employs a spray system to capture particles. |
Glossary of Terms in Powder & Bulk Technology
4. Powder Processing
Page 2 of 3
