Environmental Engineering Reference
In-Depth Information
vides valuable information, the local nature of the results should not be forgotten. A
more detailed discussion of numerical image analysis potential for the monitoring
of froth characteristics was presented by Bartolacci
et al.
[90].
Currently, commercial froth imaging systems are available to monitor different
froth parameters such as velocity, bubble size, stability and color intensity. Their in-
stallation with existing or new column flotation applications is always recommended
by equipment providers. Their use for more comprehensive process control strate-
gies should be considered by researchers and practitioners.
6.5.2 Process Control and Optimization
A challenging area for future developments is the proper on-line evaluation and
modeling of the BSD in the collection zone. Gas dispersion properties have proven
to be a key feature of the flotation process, in particular bubble surface area flux
(
S
b
), linearly correlated with the flotation rate constant, thus becoming a good po-
tential control variable to achieve a target metallurgical performance. As previously
explained, currently all the effort made to obtain a BSD is wasted through the cal-
culation of an average bubble diameter. Once properly modeled, the BSD could
be used for control purposes, either indirectly, through the
S
b
concept or directly,
leading to metallurgical benefits, particularly if it can be matched to the prevailing
particle size distribution feeding the flotation unit. Therefore, a reasonable control
formulation would be to control the bubble surface area flux being generated from
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Time (sec)
Figure 6.14
Control of the column - 2
×
2 three-phase system
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