Process equipment from Multotec, including the largest self-driven trommel the company has so far built, has been successfully commissioned at QMM’s Mandena mine in Madagascar. Installed in the mine’s heavy minerals process plant, the giant trommel is almost double the size of the Iscor Hillendale heavy minerals trommel manufactured more than 10 years ago.

Anthony Yell, product manager-screening at Multotec Manufacturing, said the  massive trommel has a 3.5-m diameter, is 15 m in length and weighs just under 50 mt. The self-driven trommel will process 3,200 mt/h of dry solids or 5,943 m3/h of heavy minerals slurry.  The process plant recovers rutile and zircon.

The South African manufacturer has fitted Spaltoflex hand-cast polyure-
thane panels, each 1,086 mm x 1,000 mm, to the trommel. These large panels with slotted apertures were selected to provide longer life and are easier to replace during maintenance. The trommel also has rubber-lined, bolt-on steel scrolls to convey the feed through the trommel in a uniform manner. It features a peripheral discharge arrangement and is driven by a Hägglunds variable speed drive system. “This hydraulic drive system allows speed variations that can be used to optimize the screening process,” Yell said.

A number of other Multotec products have also been commissioned for the wet plant. Two static screens are fitted with modular polyurethane panels (305 mm x 305 mm) and the feed boxes lined with engineered high alumina ceramic tiles to optimize wear life. All four vibrating screens at the plant also have modular polyurethane screen panels. The company’s Saddle Top system has been used to secure these panels and minimize maintenance downtime on the screens.

Vezin wet sampling systems have been installed on the rougher, cleaner and scavenger spiral circuits, allowing a representative increment sample to be taken.  The dry plant has six wet Vezin samplers, two telescopic samplers and six belt-end samplers.

Eight stacker dewatering cyclones, each 420 mm in diameter, and six rubber-lined cyclones are used for dense medium separation. In addition, two 1,200-mm-diameter, ceramic lined stacker cyclones are installed in the tailings circuit.

The plant is situated in a remote part of the Madagascar coast where there is no modern infrastructure. The QMM project included a new harbor and power station to service the plant and the local community. All the products were shipped to this new harbor.

In another technology sector, Multo-
tec Process Equipment has manufactured and supplied what it claims is the largest high-capacity cyclone cluster ever to a mine in northern China.

“The mine needed to dewater ultra-fine material, which contains valuable solids and therefore requires a very low cut point,” said Jaco Pretorius, general manager–cyclones at Multotec. “How-
ever, coupled to this was the need for high capacity. In general with cyclones, when a low cut point is required, the dimensional configuration of the cyclone is small. But since small cyclones have a low capacity, large numbers of these are required to meet the modern-day capacity requirements of large plants.” The system is able to handle higher than normal pH conditions, making it suitable for a variety of fine separation applications across a spectrum of different industries.

Multotec developed an innovative design for this application using a total of 350 cyclones, manufactured from specialized polymers, on four modular clusters to ensure optimum longevity of the cyclone. The cut point is as low as 17 micron to optimize downstream processing. The design resulted from close cooperation between Multotec metallurgical and technical specialists, the foreign project contractors, the environmental system developers and the mine to determine the most appropriate solution. Developmental test work in conjunction with Aachen University in Germany verified the data from the simulation program which Multotec operates.

In-house research, development, engineering, and test work, coupled with external research and development with various research facilities were carried out into materials of construction, configuration design, capacities and actual mechanical configuration of the equipment.

The cyclones are specifically engineered to suit applications where material buildup occurs. According to the company, development of innovative technology has achieved a non-choke design which prevents material buildup during shutdown of sectors.

“The system can be configured to operate either manually or fully automatically depending on the individual plant, its operating practice as well as the cost consideration,” said Ken Tuckey, general manager–business development at Multotec. “The system can also be custom designed to suit multi-stage environmentally required systems for flue gas desulphurization at power stations.”

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