An investigation into the use of froth colour as sensor for metallurgical grade in a copper system

In recent years the development of Machine Vision systems has opened up new possibilities for non-intrusive process performance sensors and process control. There are currently various Machine Vision systems on notation plants worldwide (Metso at Kennecott, Frothcam at Escondida). Extensive research has been done on using froth image analysis in closed loop control (Hyotyniemi et aI, 2000; Kittel et aI, 2001; Holtham and Nguyen, 2002; Cipriano et aI, 1998) and recently plants have been using these systems to control the air or level of a flotation cell as a means of controlling mass pull using the froth velocity output. As yet no flotation plants have reported the use of froth colour in their control strategies, however it is well accepted that an experienced operator can judge the metallurgical state of a flotation cell by the appearance of the froth, using colour as a key descriptor of grade, particularly in the case of copper froths. For this reason an investigation was undertaken to evaluate whether a relationship existed between concentrate grade and the froth colour obtained using a Machine Vision system. This relationship could be used to control reagent addition or for system diagnostics. Both would be invaluable tools for the flotation industry. A Machine Vision system called SmartFroth has been developed at University of Cape Town (VCT) as a research tool to investigate the relationships between froth surface indicators and metallurgical parameters. The relationship between froth colour and % solids was also investigated as it was believed that solids loading could be reflected by froth colour. This work was aimed at evaluating the empirical relationship between froth colour and copper grade in the laboratory and then investigating whether a similar relationship existed on plant. Various colour spaces were examined to find one appropriate for the copper flotation froths in order to allow for accurate colour analysis. It also evaluated the use of calibration objects in the colour analysis of flotation froths. This work also evaluated relating froth colour to % solids on plant. Two batch flotation campaigns were done using different ores as well as a preliminary plant trial.

Grantor dc:publisher.institution

Department of Chemical Engineering

Year dc:date.issued

2003

Author dc:creator

• Heinrich, Glen Sean

Advisor dc:contributor.advisor

• Bradshaw, Dee

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/11427/15427

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/15427