The recent emergence of reliable, real-time direct particle size measurement on individual hydrocyclones has overcome a long-standing, underserved need in mineral processing. It is well known that good control of the final particle size produced by the grinding-classification circuit is a critical measurement. Its poor control can have many adverse effects: e.g. lower throughput, poor flotation performance, and ultimately, lower net metal production.
In order to obtain full benefits of the commercially available CiDRA CYCLONEtrac Particle Size Tracking (PST) technology, particle size measurements of each individual cyclone overflow stream must be incorporated into the corresponding Expert Control Strategy, to take advantage of PST’s unique capability to detect on-line abnormal cyclone performance (e.g. excessively coarse product size that can lead to apex roping or plugging) of any specific cyclone at any point in time during line operation. In this context, PST allows for the implementation of selective open/close protocols for each of the cyclones around the whole classifier cluster.
In this paper the authors propose examples of advanced process control strategies that incorporate the particle size signals generated from each hydrocyclone, as could be applied to a typical SAG/Ball milling line. Proper implementation of the proposed control strategy is expected to deliver significantly lower variability of the final product size fed to downstream flotation, and thus, enable more closely approaching downstream process barriers. This is a particularly important goal given the emerging trend toward coarse particle recovery which requires grinding coarser while staying within the existing limits of the process and equipment.