Particle size analysis is a critical step during the mineral processing of raw materials. This analysis is often required during the size reduction stages of crushing and grinding (wet/dry) to mineral liberation and recovery processes such as gravity or magnetic separation, flotation or leaching to other materials and slurries. For example, comminution is an energy intensive process which requires continuous material size monitoring, particularly with changes in ore types. Extensive crushing results in too many fines whereas inadequate crushing creates overly coarse particles, poor liberation and low recoveries. The crushing process should be monitored and controlled by understanding the size distribution and shape and aspect of the daughter particles products. Optical microscopy, laser sizing and sieve shaking are well known and highly trusted techniques. While they can provide some reliable information on particle size, they lack the capability to provide accurate characterization data within short timeframes. An emerging technology, Dynamic Image Analysis (DIA) allows for particle size and shape characterisation to be carried out within minutes and yield accurate and reproducible results. Under this direct measurement technique, a wide particle size range can be measured with no requirements or assumptions such as particles being spherical. DIA generates data on particle size, shape, sphericity, aspect ratio, roundness, transparency and many more. These additional parameters provide more in-depth characterisation to assist in greater control, creating opportunities for better decision-making in real-time. The technology has also proven to work well for fine, agglomerated particles and wet suspensions where such features allow this technology to be presented as a mine-site-ready solution, allowing operators and metallurgists to optimize their measurement process for quick and accurate particle size characterisation results.
CITATION:Johnson, M, OConnor, L and Avadiar, L, 2019. Particle Size Analysis for Process Control: A New Approach with Dynamic Image Analysis, in Proceedings MetPlant 2019, pp 399401 (The Australasian Institute of Mining and Metallurgy: Melbourne).