Optimising thickener feedwells in minerals processing can enhance throughput, improve unit stability, reduce downtime and save companies costs, particularly when processing low grade ore.
The challenge
Inefficient or inadequate thickener feedwell designs
Almost every mineral processing operation will have at least one thickener unit set-up for separating solids from liquid, with some larger operations using more than 20 units. Diluted slurries are delivered by pipes or channels to feed open-bottomed mixing cylinders, called feedwells, in the middle of the thickener. These feedwells serve to dissipate the feed slurry momentum and also to aggregate (flocculate) fine particles to enhance the settling of material.
A thickener at WMC Resources' operation in Western Australia.
A thickener at WMC Resources' operation in Western Australia.
Flocculation in thickener feedwells is used for:
- Treating tailings
- Pre-concentrating ore before leaching and digestion
- Giving counter-current decantation washing in trains of two to 10 units
- Thickening concentrate products
- Clarifying leach solutions prior to subsequent steps, such as solvent extraction, electrowinning or precipitation
- Dealing with effluent treatment products.
Old feedwells are typically inefficient and struggle when pushed harder with greater throughput demands, unless design modifications are made.
Even new feedwells can be poorly selected for a particular application and need modifying when pushed outside of the original optimal operating range or faced with a change in feed material.
Simple improvements to thickener processes can provide companies with greater efficiencies and a much-needed boost, particularly when solid-liquid separation is a bottleneck on productivity.
Our response
Advanced computational fluid dyanmics models combined with flocculation kinetics
We have developed the world’s most advanced computational fluid dynamics (CFD) models of feedwell flocculation, which have become a powerful tool for optimising process performance.
CFD prediction of aggregate growth within a thickener feedwell.
CFD prediction of aggregate growth within a thickener feedwell.
Our models capture crucial information on the flow of fluid and solids and have been extensively used to understand the impacts of feedwell design elements and operating conditions.
In addition, our models predict distribution and adsorption of flocculant (a polymer that promotes particle aggregation), the growth and breakage of aggregated material (flocculated aggregates) and the likely rate that solids discharged from the feedwell will settle.
Optimising feedwells can ensure a company can maintain productivity despite material feed variability, and is an opportunity to save costs and energy usage.
We have world-leading expertise in combining flocculation kinetics in CFD modelling, customised to a client’s operation.
We have worked with feedwells used for a range of process steps, and for a range of clients that includes mineral processing operations, flocculant suppliers, thickener manufacturers and engineering companies.
Our work can be applied outside the minerals processing industry where thickener processes are used, such as paper-making and wastewater treatment.
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