Evaluation of optical sizing methods

Ontimization of blasting is hampered by the lack of inexpensive methods of measuring blast results. Optical methods of size analysis have the potential of creating a breakthrough in size analysis and in overall blast optimization. Attainment of reliable measurements hinge on solving a number of shortcomings inherent to optical systems. This paper uses the output from a commercially available optical measuring systems (Wipfrag(TM)) to assess the precision and reproducibility of measurements. Results are compared to actual crusher performance at a large-scale mine Lighting, resolution of fines, statistical precision and sampling frequency are addressed. This paper is divided into two parts. The first section addresses the question of how many samples are needed to achieve statistical significance. The final section covers optical resolution and the problem of 'lost fines'.