Abstract

Control engineering in mineral processing continues to grow as a result of more demanding conditions such as low grade ores, economic changes (including reduced tolerance to risk), and ever more stringent environmental regulations, among others. These have motivated technological developments on several fronts such as: a. Advances in robust sensor technology. On-line sensors such as flowmeters, density gauges, and particle size analyzers have been successfully used in grinding cir- cuit control. Machine vision, a non-invasive technology, has been successfully implemented for monitoring and control of mineral processing plants (Duchesne, 2010; Aldrich et al., 2010; Janse Van Vuuren et al., 2011; Kistner et al., 2013). Some commercial vision systems are VisioRock/Froth (Metso Minerals), FrothMaster (Outotec) and JKFrothCam (JK-Tech Pty Ltd).Other important sensors are pH meters, level and pressure transducers, all of which provide a signal related to the measurement of the particular process variable. This allows the final control elements, such as servo valves, variable speed motors, and pumps, to manipulate the process variables based on signals from the controllers. These sensors and final control elements are used in many industries besides the minerals industry, and are described elsewhere (Edwards et al., 2002; Seborg et al., 2010). b. Advances in microprocessor and computer technology. These have led to the development of more powerful Distributed Control Systems (DCS) equipped with user friendly software applications that have facilitated process supervision and implementation of advanced control strategies. In addition, DCS capabilities combined with the development of intelligent sensors have allowed integration of automation tasks such as sensor configuration and fault detection. c. More thorough knowledge of process behavior. This has led to more reliable mathematical models of various important process units that can be used to evaluate control strategies under different simulated conditions (Mular, 1989; Napier-Munn and Lynch, 1992; Burgos and Concha, 2005; Yianatos et al., 2012). d. Increasing use of large units, notably large grinding mills and flotation cells. This has reduced the amount of instrumentation and the number of control loops to be implemented. At the same time, however, this has increased the demands on process control as poor performance of any of these large pieces of equipment will have a significant detrimental impact on overall process performance.