Mining and Minerals

Sampling, Assay Quality Assurance and Umpire Testing

Every tonne bought, sold, reconciled or reported rests on a sample weighing a few hundred grams, and a sampling error cannot be corrected by any amount of care in the laboratory afterwards. This course starts at the sample. Delegates work through sampling theory in usable terms: the fundamental error, correct sample mass for a given particle size, and why a scoop off a stockpile is not a sample. Sampling systems are covered for stopped belt, cross belt and cross stream cutters, including cutter geometry and the bias each design can introduce. Sample preparation follows, covering crushing, splitting and pulverising, and contamination between samples. Assay methods are addressed at a level that lets a non chemist question a result. Quality assurance is covered properly: certified reference materials, blanks, duplicates and the control charts that reveal drift. Umpire assay and dispute resolution in commercial contracts are addressed. The course closes on bias testing and on investigating a reconciliation gap.