Modern Mining June 2018

PRODUCT News

FLSmidth offers economical options for large thickeners ing over the welded areas.”

Finding the optimal design and deliv- ery solution for a large thickener at a remote gold mine in the West African state of Mauritania meant considering a complex range of technical, transporta- tion and assembly options, according to FLSmidth Senior Account Manager Ricus van Reenen. The cost of transporting the compo- nents for the 50-m diameter thickener was a key factor affecting the design, says van Reenen. He says 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

mines – with the largest populations work- ing in North America, South America and Australia. “The 797 has proven its ability to deliver high production in the most challenging conditions – from the extreme cold and soft underfoot conditions of the Canadian oil sands to high altitude, deep pit cop- per applications in South America,” said Sudhanshu Singh, Global Product Manager, Large Mining Trucks. “In a broad range of applications, the 797F sets the production standard for ultra-class mining trucks. That’s a big reason why there are double the num- ber of 797s at work today compared to the total number of all competitors’ trucks in the size class.” Caterpillar assembled the 1 000th 797 and all of its predecessors at its Decatur, Illinois, USA, facility. “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.” FLSmidth, tel (+27 10) 210-4820 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 prac- tice – that is applied when erecting these large thickeners. “When supplying a thickener, part of our engineering deliverables includes an installation methodology for the site con- tractor to follow, to make sure that they implement each stage correctly,” he says. “FLSmidth also provides a technical instal- lation expert from the most suitable of our global offices who visits the site at appro- priate intervals to advise and inspect.” He further emphasises that the forces demanded within large thickeners also make the choice of gearbox drive much more important.

the need for extensive on-site welding, this option cannot easily be applied to thicken- ers larger than 50 m 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,” says van Reenen.“After the plate sections have been welded to the structure, the welds a r e s and - b l a s t ed , primed and applied with a final paint coat-

An FLSmidth concentrate thickener installation.

Caterpillar produces its 1 000th Cat® 797 truck Caterpillar recently celebrated the manu- facture of the 1 000th Cat® 797 mining truck. With 400 tons (363 tonnes) payload

capacity, the 797F model is Caterpillar’s largest truck and the largest mechanical- drive mining truck in the world. The 797 is the only mining

truck in the size class to reach the 1 000 milestone. The first 797 placed in a mining oper- ation was commissioned in 1999 and is still in service – with more than 130 000 hours working in Canadian oil sands. Extended durability has helped the 797 become a mainstay in Canadian oil sands operations. Since that time, the breadth of applica- tions has grown to include copper, coal and iron ore

A Cat 797F is loaded by a Cat 7495 rope shovel.

48  MODERN MINING  June 2018