The Radflow™ thickener feedwell: redefining thickener sizing and flocculant usage

The development and successful application of the Radflow™ thickener feedwell by Roytec Global (Pty) Ltd. is explored, showcasing an advanced feedwell design that overcomes common thickener deficiencies. Utilising scale model methodologies and computational fluid dynamics (CFD), the Radflow feedwell demonstrates superior energy dissipation compared to standard industrial feedwells, optimising thickener performance. Two case studies, including one retrofit (to improve performance) and a new installation, validate the Radflow feedwell’s effectiveness. These cases highlight that traditional thickener design heuristics, specifically limiting rise rates and flux rates, are often overly conservative when an efficient feedwell design is applied. With Radflow-equipped thickeners, excessive flocculant addition becomes unnecessary, reducing operational costs and enhancing achievable underflow density. The findings advocate for relaxed scale-up safety factors in thickener design, allowing rise and flux rates closer to free settling rates observed in laboratory conditions when an optimised feedwell is utilised. This is particularly beneficial for processing slow-settling, challenging materials like clays and fine precipitates, where controlling flow dynamics is critical. Since thickener dimensions are often predetermined by external specifications, a secondary recommendation is to minimise flocculant dosing during commissioning. This reduces operational rise rates just below free settling velocities, which may be sufficient in conservatively sized thickeners. The argument can extend to a hypothetical extreme where certain conservatively sized or operated thickeners might operate without requiring flocculant, effectively functioning as conventional thickeners. Although this approach may not be practical or feasible for most thickening applications, there are cases where the use of polymer flocculants is undesirable. In these situations, the Radflow feedwell offers an effective solution through effective energy dissipation.