Particle size analysis
Particle size analysis, particle size measurement, or simply particle sizing is the collective name of the technical procedures, or laboratory techniques which determines the size range, and/or the average, or mean size of the particles in a powder or liquid sample.
Particle size analysis is part of particle science, and its determination is carried out generally in particle technology laboratories.
The particle size measurement is typically achieved by means of devices called Particle Size Analyzers (PSA) which are based on different technologies, such as high definition image processing, analysis of Brownian motion, gravitational settling of the particle and light scattering (Rayleigh and Mie scattering) of the particles.
The particle size can have considerable importance in a number of industries including the chemical,food, mining, forestry, agriculture, nutrition, pharmaceutical, energy, and aggregate industries.
Chemical Industry
There are a large number of methods for the determination of particle size, and it is important to state at the outset, that these different methods are not expected to give identical results: the size of a particle depends on the method used for its measurement, and it is important to choose that method for its determination which is relevant to its use.
Inks and Coatings
Particle size is quickly measured using the fineness of grind gauge. The gauge consists of a steel block with a series of very small parallel grooves machined into it. The grooves decrease in depth from one end of the block to the other, according to a scale stamped next to them. A typical Hegman gauge is 170mm by 65mm by 15mm, with a channel of grooves running lengthwise, 12.5mm across and narrowing uniformly in depth from 100 μm to zero.[1]
A Hegman gauge is used by puddling a sample of paint at the deep end of the gauge and drawing the paint down with a flat edge along the grooves. The paint fills the grooves, and the location where a regular, significant "pepperyness" in the appearance of the coating appears, marks the coarsest-ground dispersed particles.[1] The reading is taken from the scale marked next to the grooves, in dimensionless "Hegman units" and/or mils or micrometres.[2]
The Hegman gauge is used in the coatings industry and measures from 100 μm to zero. THE NPIRI gauge is used for ink's finer particles and measures from 25 μm to zero
Mining
The size of materials being processed in an operation is very important. Having oversize material being conveyed will cause damage to equipment and slow down production. Particle-size analysis also helps the effectiveness of SAG Mills when crushing material.
The Fisher sub-sieve sizer is still used.
Agriculture
The gradation of soils affects water and nutrient holding and drainage capabilities. For sand-based soils, particle size can be the dominant characteristic affecting soil performances and hence crop
Particle-size analysis in the agriculture industry is paramount because unwanted materials will contaminate products if they are not detected. By having an automated particle size analyzer, companies can closely monitor their processes.
Forestry
Wood particles used to make various types of products rely on particle-size analysis to maintain high quality standards. By doing so, companies reduce waste and become more productive.
Aggregate
Having properly sized particles allow aggregate companies to create long-lasting roads and other products.
Biology
Particle size analyzers are used also in biology to measure protein aggregation.