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:: Marikana Spiral Pilot Plant
The Multotec Process Equipment spiral pilot plant has been commissioned at Aquarius’ Marikana Platinum where it will be used to conduct test work on chromite removal from the circuit.
Raf Abela, product manager responsible for spirals at Multotec Process Equipment, says that in producing a PGM concentrate it is necessary to maintain low chromite levels and this is often not possible in conventional flotation plants. Substantial energy savings can also be obtained by not grinding the hard chromite mineral if it can be removed.
"It is easier to remove the chromite using a gravity concentration step such as spirals, and given that spiral is the most economical gravity concentration method for removing chromite it was decided to install the pilot plant at Marikana to obtain accurate results for detail design," Abela says.
The four stage spiral pilot plant has been on site at Marikana Platinum for four months and Abela is confident that sufficient test data will be accumulated to enable an accurate assessment to be made. He says that once the test data has been reviewed it will be possible to design the most appropriate full scale plant for this particular application.
This is the second time that the Multotec spiral pilot plant is being used for test work. The first showed excellent results for the customer and some 7000t of ore was treated on the test unit to confirm results for another chromite application.
The Multotec spiral pilot plant has a 10t/hr capacity and this is considered a competent size to obtain representative results for the design of full-scale operations. The plant, which is housed in a 2.4 x 3.2 x 12 metre high frame, comprises four spiral stages - rougher, cleaner, recleaner and scavenger.
Abela says that the spiral pilot plant is especially useful for those mines that do not have the capital required to build their own pilot plant. The plant can be hired for a fixed period of time and provides accurate data using normal operating parameters.
The self-contained spiral pilot plant is compact in design and can be transported to site using a single 12 metre lowbed truck. The plant is easy to erect on-site using a crane to manoeuvre it onto a concrete base where it is secured in place.
Set-up is simple - all that is required is to connect the process feed line, the power line and the water line to the pilot plant.
"Desliming cyclones and a sampler to provide accurate feed data are placed ahead of the rougher spirals. This is followed by inter-stage pumping using vertical spindle pumps, a dewatering cyclone ahead of the scavenger spirals, cleaners and recleaner spirals followed again by samplers for the two final products. A stack system is used for both products," Abela explains. Automatic samplers ensure accurate and representative samples.
An important aspect in the design of the spiral pilot plant was to ensure flexibility. This means that the plant can be used to treat almost any type of heavy mineral such as beach sands, titanium, chromite, iron ore, silica sand and tin tantalum.
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