On-Line Bubble Size Analyzer for Collection Zone in Industrial Flotation Machines

Abstract

Abstract Video cameras and image analysis software to measure the top of the froth parameters (velocity, stability, bubble size distribution, bubble load, color and texture) have been proposed to control and to enhance the metallurgical performance. Nevertheless, these measurements are based on a 2D image and empirical strategies, which are insufficient to interpret froth bed hydrodynamics and collection zone kinetics, being both aspects controlling factors in flotation. One of the variables directly related with flotation kinetics and fundamental models are the bubble size distribution in the collection zone (below froth interface). However, sampling and measuring bubble size in collection zone is complex due to the presence of dark particles and bubble clusters. To make possible an industrial measurement for control purposes, a new on-line analyzer based on McGill University bubble viewer , was developed and evaluated at industrial flotation machines. The device incorporates actuators and a PLC to automate: bubble sampling, image acquisition and a washing system. To increase reliability and accuracy of the measurement; new image analysis software is developed, which identifies single bubbles from cluster and eliminates dark area from an image. The prototype and software were evaluated in industrial flotation machines at Codelco-Chile, and has been awarded for the innovations incorporated. The results indicate that the device may be used at industrial scale and the bubble size distribution appears as a new control variable to improve metallurgical performance in industrial flotation machines.