Visual observation of" the metal-bearing froth is the traditional method of feedback for the manual control of flotation. Following recent developments of measuring instrumentation, on-line control computer may now enter the flotation plant.
Summary--An industrial flotation circuit with successive stages of flotation and recycling material is studied in preparation for digital control. After considering the steady state and dynamics of the circuit, a study of the feedback control, based on a linearized model, has been carried out using standard graphical and analytical methods. Good inherent process stability is observed.
A model of the circuit with two floatable particle types, controlled by feed-forward and feedback methods, was created using a CSMP digital/analog simulator. Feedforward gives a better compensation for feed concentration, which is considered the main disturbance, but feedback is needed for several other disturbances, non-linearities, etc. A combined method is being developed and will be used for practical computer control. At the same time values of process parameters are being determined by data collection and statistical analysis, in order to expand the model. NOTATION C Concentration, based on unit airless volume (of the feed) (sometimes ~ in solids) K Gain factor k Flotation rate coefficient p Sub-index for the pulp body Q Airless volumetric flow rate (of the feed) s As sub-index refers to the steady state t Time; as sub-index refers to the tailing channel V Airless pulp volume of the cell Ratio of the change of Qt to the change of Q Time constant oJ Angular frequency.