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Coarse particle flotation

Optimising ore recovery with coarse particle flotation

The opportunities offered by coarse particle flotation to optimise resource recovery while reducing energy and water consumption have long been recognised. However, until recently, coarse particle flotation remained a technical challenge. Current innovations in flotation technology, such as coarseAIR™ Coarse Particle Flotation, are changing that.

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The limitations of conventional flotation 

Conventional flotation circuits rely on grinding feed to a fine particle size distribution to liberate the valuable ore and facilitate efficient separation. Coarser particles are not well recovered in such circuits and are frequently lost to tailings. Mines thus tend to over-grind material to avoid such losses, increasing mill wear and energy consumption. By increasing the particle size at which acceptable flotation recovery is possible, coarse particle flotation changes the equation, allowing the mill to operate at a coarse grind, with multiple benefits for mill operation and downstream separation processes.  

The benefits of coarse particle flotation are becoming increasingly apparent as mines are forced to process lower-grade deposits and, thus, a greater volume of material to maintain production levels. Coarse particle flotation can improve the efficiency of processing these low-grade deposits, allowing mines to tap into previously uneconomical reserves to help meet the growing demand for metals and minerals.

Key benefits of coarse particle flotation

  • Increase plant throughput

    Coarser grinding allows more material to pass through the mill within the same timeframe without costly investment in additional grinding capacity. This benefit compounds when twinning coarse particle flotation with other innovative flotation technologies such as the REFLUX™ flotation cell (RFC™).

  • Reduce energy consumption

    Coarser grinding tends to be less energy-intensive, allowing increased throughput without substantially increasing energy consumption. Plants may also opt to maintain throughput to lower energy consumption in the mill.

  • Enhance metallurgical recovery

    Coarse particle flotation recovers minerals otherwise lost in conventional flotation circuits. In some cases, it has been shown to recover more than 60% of the target mineral that would have been lost to rougher or scavenger tailings.

  • Improve tailings and water management

    Coarse particle flotation naturally produces coarser tailings, which are far easier to dewater. This facilitates innovative tailings disposal methods, such as FLS’ EcoPaste tailings, which involves vacuum filtering and mixing coarse tailings with finer, thickened paste tailings and waste rock/overburden to form a geotechnically stable product that improves safety and increases process water recycling.

Introducing coarseAIR Coarse Particle Flotation

Developed by Prof. Galvin and the University of Newcastle and based on REFLUX technology, coarseAIR flotation cells combine a low-turbulence, aerated fluidised bed with inclined lamella plates. The low-turbulence environment reduces the risk of bubble-particle detachment, a key cause of coarse particle loss in conventional flotation cells. At the same time, the fluidised bed acts as a semi-permeable layer, preventing the loss of bubble-attached coarse particles. The lamella region enhances bubble-liquid separation and rejects any misplaced particles, as unattached particles carried hydraulically into the lamella region are rejected back to the separator, resulting in a high-grade coarse concentrate.

Implementing coarse particle flotation

The use of coarse particle flotation technologies is gaining momentum in various mining applications. It’s particularly suited to base and precious metals processing, including copper, molybdenum, gold, silver, lead, and zinc applications, and industrial mineral beneficiation, such as phosphate, potash, and feldspar.  

Another promising area for coarse particle flotation deployment is in the retreatment of tailings, which often contain a coarse ore fraction lost in conventional flotation processes. Coarse particle flotation can be used to scavenge these valuable materials, recovering material that would otherwise go to waste while reducing the volume of material sent to tailings.  

As the mining industry faces mounting environmental and regulatory pressures, implementing coarse particle flotation offers a pathway to a more sustainable future. By reducing energy consumption, enhancing water recovery, and recovering valuable materials that would otherwise be lost to tailings, coarse particle flotation will be crucial in aligning mining operations with environmental and production goals.  

These benefits place coarse particle flotation at the heart of FLS MissionZero Mine flowsheets of the future, allowing mining operations to operate in a challenging global market, optimising resource utilisation while meeting enhanced ESG commitments and powering the transition to a greener economy. 

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