State of the art and challenges in mineral processing control

Abstract

The objective of process control in the mineral industry is to optimise the recovery of the valuable minerals, while maintaining the quality of the concentrates delivered to the metal extraction plants. The paper presents a survey of the control approaches for ore size reduction and mineral separation processes. The present limitations of the measurement instrumentation are discussed, as well as the methods to upgrade the information delivered by the sensors. In practice, the overall economic optimisation goal must be hierarchically decomposed into simpler control problems. Model-based and AI methods are reviewed, mainly for grinding and flotation processes, and classified as mature, active or emerging.

Benefits of optimisation and model predictive control on a fully autogenous mill with variable speed

“…As the benefit of milling circuits is usually expressed in terms of liberation or particle size distribution of the product (Hulbert, 2002;SosaBlanco et al, 2000;Hodouin et al, 2001), the optimal operating region is defined as the limits conducive to the best grind. These limits were obtained by conducting two optimisation trials.…”

Economic performance assessment of two ROM ore milling circuit controllers

“…The optimization of grinding and flotation circuits individually does not necessarily result in optimal performance of the overall system. The operation of the milling circuits has a great influence on the economic performance of a mineral processing plant, but investigating the economics of grinding circuits alone cannot yield a satisfactory result, as the major economic influence of the milling operation occurs in the downstream processes (Hodouin et al, 2001). A unifying study, considering the grinding and flotation circuits together, is employed in this paper for the economic assessment of the milling circuit being considered.…”

“…There are several reasons for this selection. The PSD setpoint is usually selected based on a trade-off that too fine a grind maximises the mineral liberation at the expense of throughput and high energy cost, whereas too coarse a grind decreases concentrate grade because of the presence of midlings (Wills and Napier-Munn, 2006;Hodouin et al, 2001). Maximising the net revenue of the recovered mineral tends to decrease metallurgical performance and increase the loss of valuable minerals (low recovery) to the plant tailings, which has ethical implications for resource conservation and environmental concerns (Sosa-Blanco et al, 2000).…”

“…Theoretically, the PSD setpoint should be selected based on the relation between recovery and grinding circuit product PSD. However practically, the narrowest PSD in the size range of maximum recovery is obtained at the design or tuning stage of the grinding circuit, and the operation is controlled at a single target (Hodouin et al, 2001). …”

“…Grinding mill circuits are the most cost-intensive unit processes in the mineral processing industry, so their relevant economic performance analyses remain important (Wills and Napier-Munn, 2006;Hodouin et al, 2001). However, the performance is often not estimated satisfactorily (Hulbert, 2002;Lo et al, 1996;Radhakrishnan, 1999;Bourassa et al, 1995).…”