Particle Size Analysis and Distribution – Particle Characterisation Services by LSM Analytical Services

Background

LSM Analytical Services offer a large and diverse range of modern analytical testing facilities that cater for a vast range of industry sectors. LSM’s success has been achieved by building on a strong reputation for low cost, fast accurate turnaround. The laboratory activities are backed up by accreditation to the ISO 17025 (UKAS) and 9001:2000 laboratory and quality management standards. LSM is able to offer complete analytical solutions from its internationally recognised team of technical experts, with in depth knowledge, allowing its customers to benefit from impartial guidance.

LSM’s range of analytical services includes:

• X-Ray Fluorescence Spectrometry (XRF)
• X-Ray Diffraction (XRD)
• ICP Optical Emission Spectrometry (ICP-OES)
• Atomic Absorption Spectrometry (AAS)
• Carbon, Sulphur, Nitrogen, Oxygen Analysers
• Boron analysis by the Neutron Transmission method
• Colorimetric and Volumetric Analysis
• Particle Size Analysis

Particle Size Analysis

LSM Analytical Services large range of analytical techniques includes a range of instrumentation for particle size analysis, including classical methods, sieve testing and laser diffraction.

The Importance of Particle Size Analysis

Particle size affects many of the properties of materials such as strength, stability and flow ability. Hence particle size measurement is an important feature in many industries.

Types of Particle Size Measurements

Particle size measurement equipment tends to be of one of two types. Ensemble methods look at the entire distribution without looking at the individual particles. An example of this type is the simple sieve test. Particle counting methods look at the size of many individual particles and then assume the distribution for the whole population.

The Importance of Obtaining Representative Samples on Particle Size Analyses

Obtaining a representative sample is a key issue for all analytical techniques and particle size distribution is no different. The ease with which this can be done depends very much on the material to be sampled. For powders which are cohesive and where the particle sizes are similar this task is relatively simple. However when the particle size distribution is large, mechanical vibrations occurring during sample handling and transport can lead to size segregation. Larger particles tend to rise to the top so a scoop sample would not be adequate.

Particle Size Distribution via Sieve Analysis

Particle size distribution can be assessed visually or by using a set of sieves, where a representative sample of known weight of particles is passed through a set of sieves of known mesh sizes (arranged in downwards decreasing mesh size). After vibrating for a set period the percentage of particles on each sieve is determined.

High Tech Particle Size Analysis Techniques

There are a number of more complex methods and techniques to measure particle size. These include the use of laser diffraction, electrical sensing zone (known as Coulter counter), light scattering, optical reflectance, acoustic attenuation, imaging, hydrodynamic fractionation and photon correlation spectroscopy.

Particle Size Analysis by Laser Diffraction

LSM Analytical Services offer a number of techniques for particle size measurement from traditional classical methods, through sieve testing to the most popular laser diffraction. Laser diffraction is generally the method of choice for many customers due to its rapidity and robustness. It is an ensemble technique capable of measuring large samples over a wide size range. It also has high sensitivity to oversize material.

Source: LSM Analytical Services

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