Abstract: The morphology, mineralogical and chemical
composition of a low-grade nickel ore from Mpumalanga, South
Africa, were studied by scanning electron microscope (SEM), X-ray
diffraction (XRD) and X-ray fluorescence (XRF), respectively. The
ore was subjected to atmospheric agitation leaching using sulphuric
acid to investigate the effects of acid concentration, leaching
temperature, leaching time and particle size on extraction of nickel
and cobalt. Analyses results indicated the ore to be a saprolitic nickel
laterite belonging to the serpentine group of minerals. Sulphuric acid
was found to be able to extract nickel from the ore. Increased acid
concentration and temperature only produced low amounts of nickel
but improved cobalt extraction. As high as 77.44% Ni was achieved
when leaching a -106+75μm fraction with 4.0M acid concentration at
25oC. The kinetics of nickel leaching from the saprolitic ore were
studied and the activation energy was determined to be 18.16kJ/mol.
This indicated that nickel leaching reaction was diffusion controlled.
Abstract: The copper flotation tailings from Konkola Copper
mine in Nchanga, Zambia were used in the study. The purpose of this
study was to determine the leaching characteristics of the tailings
material prior and after the physical beneficiation process is
employed. The Knelson gravity concentrator (KC-MD3) was used for
the beneficiation process. The copper leaching efficiencies and
impurity co-extraction percentages in both the upgraded and the raw
feed material were determined at different pH levels and temperature.
It was observed that the copper extraction increased with an increase
in temperature and a decrease in pH levels. In comparison to the raw
feed sample, the upgraded sample reported a maximum copper
extraction of 69% which was 9%, higher than raw feed % extractions.
The impurity carry over was reduced from 18% to 4 % on the
upgraded sample. The reduction in impurity co-extraction was as a
result of the removal of the reactive gangue elements during the
upgrading process, this minimized the number of side reaction
occurring during leaching.