Pre-concentration improves profitability
Valuable minerals are often softer or more friable than gangue minerals and are hence concentrated in the fine size fractions after initial breakage stages. If the ore exhibits a grade by size relationship screening can be an effective method of pre-concentration. Screening is simple, has high capacity, low cost and low technical risk.
Sensor-based bulk ore sorting
Where the grade by size relationship does not allow effective separation it may be possible to achieve an upgrade using sensor based ore sorting (SBOS). SBOS relies on one or more sensors measuring the ore on a conveyor. A mechanism at the end of the conveyor diverts the ore stream to one of two directions depending on the grade of the ore, based on a cut-off value. A variety of sensors are available that measure different properties of the ore, the most common being photometric, electromagnetic, radiometric and x-ray.
To be practical in pre-concentration applications for large-scale mining operations the measurement process needs to penetrate the entire bulk of the ore and be almost instantaneous. Ore sorting benefits from the natural heterogeneity of deposits and should be implemented as early in the process as possible, where the variability is greatest, to maximise the benefits.
Pre-concentration with gravity processes requires a distinct density difference between the ore and gangue minerals at fairly coarse sizes. Finely disseminated ores are generally not suitable, as the density difference only becomes apparent when the particles are finely ground. Dense or heavy medium separation (DMS or HMS) is the most efficient gravity concentration options available, suitable for a wide variety of ores at a relatively low capital and operating cost, and should be considered during the design phase for new concentrators. However, many low-grade ore bodies may not have sufficient density difference at coarse sizes for effective separation.
Improve resource utilisation
The cut-off grade in the mine may be decreased, and mineral reserves increased.
Increased feed grade
By upgrading the plant feed
Lower operating and capital costs
Higher feed grade improves grade-recovery performance
More product per tonne of ore treated
#Conveying the future
To produce metals, minerals, aggregates and energy for today’s global needs, the mining industry must handle huge volumes of material, sometimes move entire mountains. Today, mines are being challenged to re-think how they can remain profitable and be socially and environmentally responsible moving into the future.