Nonlinear Control of Coal Separation in a Jig

Abstract Discussion on nonlinear control of coal separation in a jig using a float or, more recently introduced in the industry, radiometric density meters applied to measure the density of the separation coal layer, have been presented. The main signals describing the separation process are: the flow rate of the discharged refuse as the control signal, the density of the separation coal layer as the output signal and the raw coal feed rate and its washability characteristics as disturbances. A jig is a highly nonlinear control element for changes in all input signals, however, in most industrial float control systems usually there can be found linear P controllers in order to achieve stable operation and avoid frequent oscillations. There has been presented a comparison of effects of various nonlinear strategies of control, using a developed simulation model of coal separation process, which was verified during industrial tests. The analysis showed a distinct advantage of systems with a radiometric meter over systems with a float measuring the stabilized density of the coal separation layer and advantage of nonlinear PI controllers over commonly applied P or PI linear controllers.