Environmental Engineering Reference
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hold-up monitoring. This technique was recently successfully tested by Arizmendi
et al.
[41] for solid hold-up measurements. Such a technique could become a low-
cost and safer substitute for gamma-ray density meters. In its original application,
the standard addition method remains the only available method for gas hold-up
estimation in the froth zone.
Supervision methods based on multivariate image analysis (MIA) are promis-
ing options to overcome OSA limitations and to monitor froth characteristics. MIA
potential applications for concentrate grade prediction have been reported by Duch-
esne
et al.
[88]. Liu
et al.
[89] presented a novel method to extract textural and color
information related to the froth zone BSD, and the presence and amount of clear
windows in flotation froths. Liu and McGregor [70] also showed that the scores of
the MR-MIA (multiresolution multivariate image analysis) could be directly used
in froth control. Froth image analysis based on MIA could become the alternative to
some instrumentation problems of flotation columns, for instance, to monitor water
entrainment. In fact, if the froth color and/or texture are related to the froth water
content, it is possible to build a regression model linking froth image characteristics
to concentrate water content. Like for any image analysis application, conclusions
would be drawn using only surface features, therefore, even if the technique pro-
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Figure 6.13
Column control - 3
×
3 two-phase system
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