Froth Flotation’s Newest Machines: How Much Better Are They?

“An order of magnitude savings…; a paradigm shift in flotation technology…” (Woodgrove Technologies, 2024) “Revolutionising copper concentration…” (International Mining, 2024) “[Only requires] two reactor-separator units” (Maelgwyn Mineral Services Africa Pty Ltd, 2024) “Effectively replaces ten conventional flotation cells” (FLSmidth, 2024) In recent years, dual-chamber flotation machines have gained increased acceptance, particularly in retrofit or cleaner-scalper applications. However, despite the marketing claims, most large greenfield projects continue to install conventional mechanical flotation cells instead of the supposedly more efficient dual-chamber machines. What gives? Are these new machines really as good as claimed, or do the mining or engineering companies know something we don’t know? In this paper, we examine these questions. A new compartmental model of flotation is proposed, one that is effective for both single- and dual-chamber machines. An example model calibration is provided, from test work performed at Capstone’s Pinto Valley concentrator, showing that the new approach works well for dual-chamber flotation cells. The proposed model is then used to evaluate the key operating and design parameters for flotation circuits with dual-chamber flotation cells. The results are surprising. The collection of hydrophobic particles in the mixing chamber appears to be very high, but due to froth recovery effects and secondary collection in the separation chamber, the machine performance is less sensitive to mixing chamber recovery than many would expect, suggesting that the design of the mixing chamber is unlikely to significantly impact the overall machine performance. The impact of separation chamber residence time and internal recycle rate is only relevant when the froth recovery is low; at high froth recoveries, there is no metallurgical benefit to either. Lastly, the study shows that single most important driver impacting overall performance is the froth recovery, suggesting that most dual-chamber machines will excel if equipped with aggressive froth management systems.