Optical measurements for flotation monitoring and diagnostics


Mineral beneficiation processes lack on-line instrumentation for process monitoring and control. Using the latest on-line optical instrumentation for monitoring important process parameters of each stage together with advanced process control would enable better control and optimization of the processes, leading to savings in raw material use, chemicals, water and energy. The on-line measurements could also be used as a part of the process diagnostic system, aiding in disturbance detection and timely recovery.

Froth flotation is a widely applied separation process in minerals processing. In this study, a machine vision –based system measuring bubble size inside the flotation cell to obtain faster response to the changes in the process in order to improve flotation control and yield is presented. Additionally, the system gives better understanding of bubble behaviour in different depths of flotation cells. The applied modular imaging probe consists of an illumination unit, a viewing unit and an electronic unit. The performance of the technique was verified in a laboratory batch reactor and continuous minipilot mineral beneficiation plant located at Oulu Mining School Research Centre, University of Oulu, Finland.

During the experimental campaigns, it was verified that the bubble size measurement can observe changes in flotation performance and thus the system can be used for on-line process monitoring. Moreover, it was noticed that because of ore type variation large particles of grinded ore occasionally accumulated at the bottom of the flotation cells, damaging the equipment and preventing the formation of the bubbles. The optical probe could be detect the disturbance and could be used for process diagnostics to prevent the downtime of the process timely.