The basic purpose of sampling is to collect a manageable mass of material which is representative of the total mass of material from which it was collected. This manageable mass of material is called a sample and is subject to certain preparation procedures that render it suitable for either physical testing or laboratory analysis. The types of tests or analyses that are performed are dependent on what characteristics are required to be measured.

Methodology

The method by which samples are collected, the frequency of collecting samples and the accuracy of the samples collected, that is, how closely they represent the true characteristics of the total mass, all depend on the nature of the material being sampled. A totally homogeneous material will require the collection of only a single sample to determine its characteristics accurately. In contrast, a lumpy heterogeneous material, such as coal, will require many small samples or increments which, when combined, will represent the total mass or lot with an acceptable degree of accuracy and precision. These increments should be collected from all parts of the lot. The number of increments required is dependent upon the variability of the material constituting the lot.

Accessibility

Since the increments must come from all parts of the lot, the total lot must be accessible. It is fundamentally important that all particles in the lot have the same probability of being included in the final sample. This is one of the “golden rules” of sampling. To achieve this requirement it is desirable to sample the lot whilst it is in a dynamic state. Sampling may be carried out by either manually or by mechanical means, the latter being more preferable with respect to operator safety and correct sampling. There are distinct advantages using mechanical sampling.

Importance of Understanding Sampling

Because many decisions are based on results of sampling, particularly those of a commercial nature, sampling is one of the most important operations carried out during the mining, beneficiation and ultimately the use of coal and mineral commodities. Yet despite this, sampling is often than not one of the most neglected and least understood operations in the mining and process industries.

In addition, where mechanical sampling is used, SGS often finds that inappropriate maintenance and modifications lead to poor performance of the sampling operation. SGS can perform technical audits and provide on-going maintenance to ensure the best possible sampling with the existing equipment.

Ultimate Control

In this age of sophisticated laboratory analytical equipment and methods for calculating and reporting results, no matter how accurately the final laboratory analysis is performed, the results obtained cannot be anymore accurate than the degree of accuracy with which the initial sampling operation was performed.

Learn more about:

• Bias Testing
  
• Technical Audits