The Effects of Ore Properties on the Characterization of Suspension in Settling and Compression

Document Type: Research Paper

Authors

1 Department of mining Engineering, Science and Research branch, Islamic Azad University, Tehran, Iran

2 School of Mining Engineering, University of Tehran, Tehran, Iran

Abstract

Many studies have considered the effects of suspension properties on the dewatering process but few
have focused on ore properties. Thus, the present work studied the effects of ore properties (density,
particle size, mineralogy) on the dewatering process based on lab and pilot experiments. A hydrocyclone
was used to prepare the required samples for the experiments. To study the effects of mineralogical
properties, the sedimentation behaviour of hydrocyclone feed and underflow samples were compared. It
was observed that the free-settling velocity of feed (2 to 6mm/sec) was less than in the underflow sample
(2 to 7mm/sec) and the final concentration of underflow sample (0.45 to 0.48t/m3) was more than the
feed sample (0.44 to 0.47t/m3). Additionally, to study the effects of particle size and density, the
sedimentation behaviour of hydrocyclone overflow and feed samples were compared. The settling
velocity and final concentration of overflow sample were obtained at 0.15 to 0.4mm/sec and 0.32t/m3,
respectively, which was significantly less than the feed sample. This was due to the amount of clay
reduction in the underflow sample and particle size and density reduction in the overflow sample.
Following on, the pilot experiments were carried out. It was observed that the bed formation of the feed
sample tended to overflow in the sample at low flux (10t/m2/day) and tended to underflow in the sample
at high flux (28.5t/m2/day). This meant that the long time at lower flux created an opportunity for fine
particles to settle easily, similar to coarser particles and as such, ore properties did not play a decisive
role in bed formation, but their effects appeared instead at higher flux. Furthermore, it was observed that
the underflow concentration increased by decreasing the flux from 28.5 to 10t/m2/day. These increasing
amounts were 0.05t/m3 and 0.12t/m3 in hydrocyclone overflow and underflow samples, respectively, at a
height of 2.5 metres. This meant that the compressibility and permeability of the hydrocyclone
underflow sample was much better than in the hydrocyclone overflow sample, which was clearly a result
of the ore properties (density, particle size, mineralogy).

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