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MEI Online: Magnetic/Electrical Separation: Latest News: February 15th 2005

 
 

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:: Magnetic Test Faciilties at Multotec Eliminate Guesswork

Two new magnetic test units have been added to the test facilities at Multotec Process Equipment, and will assist in the selection of the most appropriate magnetic process equipment for a given application by minimising guesswork from the process engineer’s side.

Renira Reddy, process engineer for the gravity concentration division at Multotec Process Equipment, says that test work is common practice at Multotec. In this division, comprehensive spiral concentrator test work has been done for the past twelve years to assist the process engineer in providing process guarantees based on measured data.

"The main benefit of a test facility, such as the one at Multotec, is that tests are conducted in a controlled environment where verification and validation are ensured," Reddy explains.

Samples generated from the test work done at the test rig are usually returned to the client for analysis. These analyses are returned to a process engineer for data processing that will then highlight factors such as process requirements, upgrading, recoveries and mass pulls.

"This level of testing facilitates the appropriate design of new plants as well as the effective upgrading of existing processes," Reddy says. Multotec has a number of full scale and pilot scale units that can generate reliable results without the need for scale-up in many cases.

Among the recently commissioned test equipment is a Dry Magnetic Roll Separator, which is designed for the dry magnetic separation of material using rare earth roll magnets in different configurations. A magnetic field strength of 10 000 Gauss is used for separation of weakly susceptible materials such as illmenite from beach sands.

A 100 mm diameter roll is used under a thin Kevlar belt to optimise the magnetic recovery of the material. There is no need for scaling up from his unit as the full scale units also operate with a 100 mm roll, except that the roll length is increased to allow for increased capacity.

In theory, minerals which are not attracted to the magnetic field will be thrown off the belt along the trajectory created by the rotating roll. Minerals which are attracted to the magnetic field will stick to the magnet against the belt and only fall off the belt when it moves out of the field.

A magnetic roll is made up of magnet and pole slices which are sandwiched together in an alternating manner to form a roll. Different role configurations in terms of magnet and pole widths are available to facilitate the testing of a wide variety at different particles sizes.

The mass pull recovered to the magnetic and middlings fraction can be varied according to the magnetic and non-magnetic separation requirements. This is achieved by adjusting the product splitter. The feed rate to the rolls is also adjustable and under ideal conditions there should be a mono-layer of particles on the belt.

The second unit is a Medium Intensity Wet Drum Separator that allows for the wet testing of material. Fed in a continuous circuit via a gravity distributor, this pilot scale machine can process material at a rate of between 7-10 t/hr. If tested in batch mode (close circuit), samples as small as 70kg can be tested. Inside the drum is a magnet assembly with an intensity of 8000 Gauss on the drum surface. The magnet can be used to recover relatively weakly magnetic materials like illmenite, hematite and chromite.

"Use of test work such as this is often used for scoping and process validation, and work has already been undertaken on a number of different materials," Reddy concludes.

Other test units available at Multotec Process Equipment include :

  • A Low Intensity Permax Wet Drum unit designed for plant scale test work for the recovery of magnetite and ferrosilicon in dense media plants.
  • An Induced Roll unit designed for test work on minerals sands processing or purification and/or concentration of granular minerals applications.
  • A Rare Earth Drum unit designed for treating industrial minerals in a dry application.
  • An Eddy Current Separator suitable for test work on aluminium, copper and scrap metal. This unit separates conductors from non-conductors by inducing a charge on the material with a moving magnetic field.

 

 

   

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