A Dual-Loop Control System for Dense Medium Coal Washing Processes with Sampled and Delayed Measurements

A dual closed-loop control system is developed for a dense medium coal washing process. The controller is designed to improve the separation efficiency and energy efficiency of the dense medium cyclone coal beneficiation process simultaneously making use of a model predictive control method and a pumped-storage system (PSS). In the dual-loop control, the outer loop is designed for medium density profile optimization and the inner loop is used for actuator control of the medium supplying circuit, considering the interplay of the energy efficiency and separation efficiency. Mathematical models of the PSS and the magnetite recycle process of the dense medium circuit are developed and employed in the design of the advanced controller. The effectiveness of the designed control system is demonstrated by simulations based on operational data from a South African coal beneficiation plant.