Adding Value by Dry Gravimetrical Sorting of Hematite Ore GSort

Adding Value by Dry Gravimetrical Sorting of Hematite Ore

Article published on © Austrian Society for Metallurgy of Metals (ASMET) and Bergmännischer Verband Österreich (BVÖ), August 9, 2021

By introducing dry gravimetrical sorting as an additional step in the
process of ore sorting, it is possible to add value by:

  1. increasing the average recovery of iron and
  2. reducing the amount of low-grade iron ore going into the wet process,

and by doing so, to either increase the total production capacity or reduce the amounts of the tailings. Based on 1 mio t run-of-mine ore per annum, the increased revenue after the implementation of the ALLGAIER dry gravimetrical sorting can be estimated at 15 mio €, the CAPEX for installing the plant at 5 mio €, and the OPEX cost for running the operation at 1.5 mio €.


Hematite is the world’s most important iron ore. Today almost all production comes from a few dozen large deposits where significant equipment investments allow companies to efficiently mine and process the ore. Most of the ore is being produced in China, Australia, Brazil, India, Russia, Ukraine, South Africa, Canada, Venezuela, and the United States.
Hematite is mined in some of the largest mines in the world. These mines require investments of billions of dollars, and some will treat over 100 mio t of ore per year. These open-pit mines can be hundreds to thousands of feet deep and several miles across by the time they have been worked to completion.


The density separation process is based on a tilted, vibrating deck. An upward air stream passes through this deck, having two important effects on the materials being separated:

Particles with a lower density will float downwards on a cushion of air, without any contact with the deck,

Particles with a higher density will remain in periodic contact with the deck and are conveyed upwards by the vibration.

The ALLGAIER GSort has the possibility to adjust many running parameters individually, quickly, and easily, ensuring that the machine is always perfectly tuned for the materials being separated. This high precision is achieved by adjusting the following parameters:

Flow and airspeed distribution
Overflow fap height
The inclination of the table
Vibration frequency

This flexible configuration ensures that a large range of materials can be processed.

For a specific product mix, the production capacity depends on the difference in material density. The treatment of the exhaust air takes place via cyclones or bag filter systems, which separate air and dust. The cleaned air is extracted by a fan.

Read the complete article at Adding Value by Dry Gravimetrical Sorting of Hematite Ore.

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