Up-scaling of froth flotation equipment

Up-scaling of froth flotation equipment

Boeree, C.R.

Buxton, M.W.N. (mentor)
Voncken, J.H.L. (mentor)

Civil Engineering and Geosciences

Geoscience & Engineering

Resources Engineering

2014-08-22

The up-scaling of flotation equipment has been investigated based on comparisons between laboratory, pilot and industrial scale flotation tests and a characterization study of large-scale industrial flotation cells in Boliden’s Aitik copper mine in Northern Sweden. The use of high volume flotation cells has nowadays become more and more common to deal with the production of high capacity, low-grade open pit mines, which are typically copper or gold mines. Implementation of large flotation cells in the mineral beneficiation process holds several financial benefits, but gives no guarantee of an equal or improved metallurgical performance. From a historical point of view, flotation plants have been designed based on the results of laboratory tests, multiplied with a time up-scaling factor at which recovery was expected to be above a certain value on the industrial scale. Due to the uniqueness of each ore, such an experience-based factor has often resulted into under- or overestimations of the total required cell volume. One of the main differences between lab and industrial flotation in this research is found the be the behaviour of fine particles (-45 ?m), which are shown to have slower flotation kinetics and poor recovery on the industrial scale in comparison to the lab scale, but are also accompanied by a relatively high degree of gangue mineral entrainment in lab tests. A characterization of the industrial flotation equipment was done to acquire more information on the sub-processes that take place within the cells. Sampling on different depths in 160 m3 rougher and scavenger cells revealed a well-mixed regime in the lower cell half, decreasing homogeneity above a depth of 2,5 m under the froth, and an accumulation zone of fine-grained copper-rich minerals directly under the pulp-froth interface. The effectiveness of the low-turbulent zone in the top half of the industrial flotation cell is questioned, while the general trend in flotation cell design of increasing volume even shows an increasing height-to-diameter ratio, which could eventually lead to a larger fraction of the cell volume being low turbulent. To obtain more insight in the functioning of these flotation cell sub-zones, the use of a bubble load measurement is proposed to determine the recovery of both valuable and gangue minerals as a profile of cell height. Furthermore test work in a laboratory pilot scale cell with adjustable height is discussed, in which the volume fractions of the mixing zone, quiescent zone and froth zone can be varied. Combination of these two investigations is expected to allow better understanding of how an industrial flotation cell functions.

froth flotation
up-scaling
mineral processing

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Student theses

master thesis

(c) 2014 Boeree, C.R.