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Advanced Process Control - Flotation Image Analysis System for Inferential Mineral Content

Challenge: In the flotation process, it was observed that operators controlled the quality of the float material according to the colour of the froth in the cells. They were able to visually classify the types of foam into different categories and each one of them is associated with an operating strategy.

Solution: An image analysis system can detect characteristics of the froth of an online flotation cell, OptGrade©. It uses an adaptive algorithm based in optic flow stimulation (optical flow vector) for detection and analysis of the motion in addition of the detection of RGB. With these data it was possible to assess variations that must be controlled in order to maintain the grade and recovery desired. Data of grade were collected from the mineral of interest and RGB (red, green and blue) data of final concentrate of the froth. It was collected during one month of operation and RGB was obtained using a camera. It was verified that the red colour showed the same trend of the grade curve in the concentrate. Thus, the use of this online data in optimising control was introduced. The laboratory grade is used to calibrate the colour set point. Therefore it was possible to monitor in real time the trend of enrichment and depletion of a non-ferrous mineral in flotation. It was possible to establish an online control strategy based on simple data acquisition.

Results: From the use of the OptGrade© and the image analysis and control through OptProcess© expert system , an increase in recovery was possible, which resulted in an increase of 10.26% on the recovery.