Tag Archives: FLSMIDTH (PTY) LTD

HOW THE REFLUX™ CLASSIFIER INCREASES MINING PRODUCTIVITY

Delivering high levels of recovery, while managing large throughput efficiently is no easy job. So how exactly does FLSmidth’s REFLUX™ Classifier (RC™) achieve this? And, importantly, can it benefit your mining operations?

Concisely, the RC is the slurry based gravity separator designed specifically to upgrade fine minerals generally finer than 2mm. The key design element is a system of lamella plates or inclined channels and the internal overflow launders. These are contained within the Lamella Settler – the top portion of the RC. The other two main components are an Autogenous Dense Medium Separator underneath the lamella chamber, and a Fluidised Bed Separator beneath that.

Material from the process plant enters through the slurry inlet and passes over an internal over-size protection screen which removes any tramp or debris that may cause damage to the ceramic underflow valve. Large, high-density solids quickly sink and settle in the mixing chamber that is in the middle section of the classifier, forming a fluidised bed of dense material. The fluidised bed is created by a series of water jets at the base of the mixing chamber and rejects any trapped lighter particles.

Lighter and finer particles rise in the RC, through the autogenous zone to the lamella section. The autogenous section is created by fine suspended solids, and this zone helps convey lighter particles to the lamella section.

This upper section contains the crucial sloping lamella channels, that are typically placed 6mm apart – although this distance can be reduced for finer materials. Low density particles rise up through these channels, driven by the upward water flow from the feed. The narrow sloping channels cause a parabolic flow pattern, where the flow is fastest midway between the channel walls.

The lightest particles are carried by the faster flow before they can settle and they overflow at the top of the channel. They fall into internal launders and are discharged from the RC. The higher density particles tend to slide back along the topside of the lamella channel, where the flow is slower. These particles slide down the slope, back to form the autogenous dense media zone.

Pressure probes monitor the bed density and automatically control the underflow valve to optimise the bed level and density. The fluidised bed keeps particles in suspension and rejects the lighter material up out of the bed while the denser particles sink and flow out through the underflow valve. The valve’s four-link system moves the plug vertically, which reduces wear and provides protection against splashing.

In a recent innovation, a modular RC™ plant, FLSmidth carefully selected the associated equipment – like pumps, screens, dewatering equipment and conveyors – for optimal performance. These modular plants are also automated, using advanced instrumentation and control equipment to keep operations consistent and recoveries high.

LOW-CAPACITY RECLAIM FEEDER SUITS MINES OF ANY SIZE

Adaptability is the watchword in FLSmidth’s Buffalo™ range of low-capacity modular reclaim feeders, making it a versatile offering for anything from run-of-mine applications by medium-tier miners to flexible stand-in units for larger operations when stacker-reclaimers require maintenance downtime.

According to PC Kruger, FLSmidth’s account manager for coal in sub-Saharan Africa, the modular format allows different discharge heights and loading decks of various lengths to suit the required application. It also facilitates transportation of these units in standardised containers to remote locations, after being manufactured in a dedicated FLSmidth workshop.

“Our current designs are optimal for soft, non-abrasive material such as coal and salt, as well as potash and gypsum,” says Kruger. “The modularity allows us to tailor the final product to meet customers’ specific requirement and ensure optimal productivity, with easy reclaiming using dozers or front-end loaders.”

Depending on the application and the level of mobility required, the units can be mounted on skids or even wheels to be relocated from one position on site to another. This further enhances their versatility. The motor control centre (MCC) is located onboard the reclaim feeder and only the power supply needs to be isolated before relocating the unit.

“Our reclaim feeders and feeder breakers can be installed as a free-standing unit – with or without civil works – or as a multi-unit construction with hoppers or sizers,” Kruger says. “This presents an ideal backup system for stacker and reclaimer systems, and they can be implemented for side-tipping or back-tipping applications to reduce double handling of material.”

The modularity of the units also makes for easier logistics; rather than demanding the large lifting equipment for the conventional size of composite units, this range requires much lighter lifting capacity of just two to three tonnes. The economy of this design extends to manpower, as fewer artisans are required for assembly and commissioning.

The heavy-duty design features replaceable individual parts throughout the full length of the feeder, which is powered by electromechanical and hydraulic drives. Flow control is achieved through adjustable hydraulics, variable speed drives and gearbox ratios. Pitch chains are available in 4 inch.

“A hydraulic take-up system ensures ideal and consistent chain tensioning on the shaft take-up assembly,” he adds, “with auxiliary components such as wheel assemblies, lights, lubrications systems and safety features offering a true, fit-for-purpose solution.”

The Buffalo™ brand of feeder breakers, introduced in 1975, became part of the FLSmidth group in 1999, changing its name to FLSmidth Buffalo™. The Buffalo™ acquisition has strengthened FLSmidth’s position as a market-leading manufacturer and supplier of feeders, feeder breakers and sizers. Manufactured in South Africa, FLSmidth Buffalo™ equipment is distributed globally.

FLSMIDTH HIGHLIGHTS DIGITAL FUTURE FOR MINING

In pride of place on the FLSmidth Electra Mining Africa exhibition stand this year will be a 1:20 scale model of its REFLUX™ Classifier (RC) modular plant, representing – in more ways than one – the future of processing in the mining sector.

According to FLSmidth Commercial Manager Terence Osborn, the RC plant is a good example of an integrated solution designed to a meet a customer’s tailings-related risks and requirements.

“The plant demonstrates how our insights and expertise make us more than an equipment supplier,” says Osborn. “Our focus is to bring the value of our technical knowledge base – along with our range of advanced product offerings – directly to bear on improving customers’ sustainability and profitability.”

The RC plant embodies FLSmidth’s leading technologies as well as its innovative business approach. Equipped with advanced automation facilities, a full-size version of this plant is in operation for a mining customer on an outcomes-based toll treatment, model. It treats waste product, or tailings, and recovers valuable minerals as a saleable product for the customer, without adding extra workload or risk to their operation.

FLSmidth’s technical advancement in automation and digitalization is vital in making these solutions more valuable; both FLSmidth and the customer can observe and assess the key operational parameters of the plant in real-time in their respective head offices anywhere in the world. He emphasised how much of a priority this direction was for the business.

“Our appointment in May this year of a Chief Digital Officer at global group executive level reflects our focus on digital efforts to leverage solutions,” he says. “This is key to our corporate strategy going forward and customers will see increasing levels of bottom line benefit arising from this direction.”

Osborn emphasises that Electra Mining Africa is a good opportunity to engage with operations-level customers, listening to feedback and sharing ideas about the kind of solutions that help them achieve their goals and targets.

“Our role is increasingly to provide total solutions that package our expertise and equipment for the customer’s benefit – and to make it possible for them to run efficient plants with high recoveries,” he says. “This includes our ability to effectively integrate equipment and solutions into their existing infrastructure.”

FLSMIDTH OFFERS ECONOMIC OPTIONS FOR LARGE THICKENERS

Finding the optimal design and delivery solution for a large thickener at a remote gold mine in the West African state of Mauritania meant considering a complex range of technical, transportation and assembly options, according to FLSmidth senior account manager Ricus van Reenen.

The cost of transporting the components for the 50-metre diameter thickener was a key factor affecting the design, says van Reenen. He highlights that transportation of components to remote sites can comprise a substantial portion of costs, and that break-bulk shipping costs are significantly higher than containerised transport.

“Given that the thickener components needed to be shipped by sea as well as by road, containers were considered the most economical mode solution,” he says. “This requires that the plate sections be cut and rolled in dimensions that can be packed into containers for shipping to site.
The structural support sections like the I-beams will be fabricated to final stage at our facility and just bolted on site, but the plates will need to then be welded by expert welders.”

While bolted thickeners are often more economical to construct, as they obviate the need for extensive on-site welding, this option cannot easily be applied to thickeners larger than 50 metres in diameter.

“For these larger designs, the support structure is erected on site followed by the welding together of the plate sections from one end to the other,” he says. “After the plate sections have been welded to the structure, the welds are sandblasted, primed and applied with a final paint coating over the welded areas.”

Certain cost-saving strategies can still be employed in these situations; for instance, the plates can be painted before shipping with the weld-strips left clean to facilitate on-site welding.

Van Reenen emphasises the importance of the documented assembly procedure – according to FLSmidth’s global best practice – that is applied when erecting these large thickeners.

“When supplying a thickener, part of our engineering deliverables includes an installation methodology for the site contractor to follow, to make sure that they implement each stage correctly,” he says. “FLSmidth also provides a technical installation expert from the most suitable of our global offices who visits the site at appropriate intervals to advise and inspect.”

He further emphasises that the forces demanded within large thickeners also makes the choice of gearbox drive much more important.

“Smaller thickeners can usually be designed with planetary gearbox drives – available from a number of OEMs,” he says. “With really large drives requiring higher torque, however, we prefer to use our own ring-gear Dorr Oliver drives which can reach much higher torque values than planetary drives.
The ring-gear drives are also more able to handle axial and radial loadings on the rakes.”