All decisions in process development, mine planning and process optimisation are based on analytical results. However, analytical results cannot be separated from the specific conditions under which they were obtained. Sampling comes to the fore as a critical success factor before analysis, which should only be carried out on documented representative samples as a basis for data driven, informed decisions.
While analytical results are only representative of the tiny analytical aliquot, decisions have to be made for the original lots, which are millions or billions of times larger. A single increment, or a single sample can never be representative! The main goal of sampling theory (TOS) is to be able to extract representative samples across six to nine orders of magnitude. The Theory of Sampling was established over 60 years ago and is the only theoretical and practical framework that addresses the systematics of the necessary-and-sufficient sampling principles.
Consideration of all factors affecting the accuracy (bias) and precision (uncertainty) of sampling requires the appropriate competence in all steps “from lot to aliquot”. Sampling must take into account heterogeneity at all stages in a fully documented form. TOS is the only fully developed scientific-backed framework for practical sampling.
However in many contemporary standards, ‘best practice’ manuals and guiding documents there is a lack of proper understanding, in fact making many common practices insufficient and deficient. This is particularly evident in the context of pre-concentration of ores, where large particle sizes quickly lead to required sample sizes on the scale of several tonnes.
Only when the task is clearly defined and the data has been generated correctly, can operational and investment decisions be made on fully accountable and defensible terms. SIX-S, together with KHEConsult, offers application-specific and customer-oriented advice for professional accountable sampling so that so that processes can be monitored appropriately, the right decisions made and productivity increased.
“All sampling procedures invoked to secure primary samples (as well as any sub-sampling operations required to produce the analytical aliquot) shall be 100% compliant with the principles of representative sampling as outlined in the Theory of Sampling (TOS), and as codified in the standard DS 3077 (2013). All sampling procedures must be adequately and fully documented.”
- Audits and design assistance
- Sample selection
- Test work design and management
- Equipment selection
- Establishment of sampling quality assessment, assurance and control protocols (QA, QC).
- Trainings, courses, mentoring