3302 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
and the surface composition of the rougher tailings was
determined by the energy dispersive spectrometer (EDS).
RESULTS AND DISCUSSIONS
Characterization of the Rougher Tailings
The particle size distribution of the sample is displayed in
Figure 1 (a), and it revealed that d80 was 74.65 microns.
The results complement the size-by-size deportment data
(Figure 1 (b)), as more than 80% of the valuable metals
of interest are present in the fine fraction. Hence, the feed
sample is liberated, negating the influence of particle size
during leaching. The elemental composition from the ICP-
OES analysis was computed in Table 3. The concentration
of Ni was correspondingly 1.29%, and the impurities were
mainly aluminum (Al), calcium (Ca), iron (Fe) and magne-
sium (Mg). The mineralogical composition was determined
using the XRD, and the primary minerals as displayed in
Figure 3. The powder diffraction analysis indicated that
nickel is mainly hosted in the sulfides, notably, pentlandite
(Ni9S8).
The SEM micrograph and EDS images of the rougher
tailings sample for the leaching experiments are displayed
in Figures 3 and 4, respectively. The particle morphology
indicates that the particles are irregularly shaped and of dif-
ferent sizes. The results of the EDS analysis demonstrate the
occurrence of mainly Fe at 33.5 wt.%, Ni at 32.6 wt.% and
sulphur (S) at 34.0 wt.%, which indicates the presence of
fine and coarse liberated pentlandite grains. The EDS map
displays the association of Mg and Ca with the pentlandite
locked inside the silicates.
The activated carbon (Figure 5) used for this study
was synthesized from coconut shells and activated using
steam at high temperatures. The characterization of the
commercial activated carbon (given in Table 4) indicated
that the carbon has high activity, and the pores have a large
surface area.
Response Surface Model and Statistical Evaluation
The experimental results from the CCD have been shown
in Table 6. The RSM coupled with CCD facilitated the
establishment of a statistical relationship between the
Table 3. The chemical analysis of the feed sample determined
by ICP-OES
Element Ni Al Ca Fe Mg Zn
Content (%)1.29 0.87 0.78 14.66 10.37 0.04
0
20
40
60
80
100
0.01 0.1 1 10 100 1000 10000
Screen size (microns)
(a)
0
10
20
30
40
50
60
70
80
90
100
Ni
Elements
+106 μm -106+75 μm -75+63 μm
-63+38 μm -38 μm
(b)
Figure 1. The percentage of (a) the particle size distribution (b) Ni in the different particle sizes of the rougher tailings
Table 4. The characteristics of the granular activated carbon
Property Value
Iodine number, mg/gm 1100–1200
Apparent density, lb/ft3 29–31
U.S. standard sieve size (Mesh size) 4 × 8
Butane number, %w/w 23.5 (60 CTC)
Hardness, min. (ASTM D-3802) 98
Total surface area (BET), m2/gm 1150–1250
Ash, max (ASTM D-2866) 3%
Cumulative
percent
passing
(%)Sizedeportment(%)
and the surface composition of the rougher tailings was
determined by the energy dispersive spectrometer (EDS).
RESULTS AND DISCUSSIONS
Characterization of the Rougher Tailings
The particle size distribution of the sample is displayed in
Figure 1 (a), and it revealed that d80 was 74.65 microns.
The results complement the size-by-size deportment data
(Figure 1 (b)), as more than 80% of the valuable metals
of interest are present in the fine fraction. Hence, the feed
sample is liberated, negating the influence of particle size
during leaching. The elemental composition from the ICP-
OES analysis was computed in Table 3. The concentration
of Ni was correspondingly 1.29%, and the impurities were
mainly aluminum (Al), calcium (Ca), iron (Fe) and magne-
sium (Mg). The mineralogical composition was determined
using the XRD, and the primary minerals as displayed in
Figure 3. The powder diffraction analysis indicated that
nickel is mainly hosted in the sulfides, notably, pentlandite
(Ni9S8).
The SEM micrograph and EDS images of the rougher
tailings sample for the leaching experiments are displayed
in Figures 3 and 4, respectively. The particle morphology
indicates that the particles are irregularly shaped and of dif-
ferent sizes. The results of the EDS analysis demonstrate the
occurrence of mainly Fe at 33.5 wt.%, Ni at 32.6 wt.% and
sulphur (S) at 34.0 wt.%, which indicates the presence of
fine and coarse liberated pentlandite grains. The EDS map
displays the association of Mg and Ca with the pentlandite
locked inside the silicates.
The activated carbon (Figure 5) used for this study
was synthesized from coconut shells and activated using
steam at high temperatures. The characterization of the
commercial activated carbon (given in Table 4) indicated
that the carbon has high activity, and the pores have a large
surface area.
Response Surface Model and Statistical Evaluation
The experimental results from the CCD have been shown
in Table 6. The RSM coupled with CCD facilitated the
establishment of a statistical relationship between the
Table 3. The chemical analysis of the feed sample determined
by ICP-OES
Element Ni Al Ca Fe Mg Zn
Content (%)1.29 0.87 0.78 14.66 10.37 0.04
0
20
40
60
80
100
0.01 0.1 1 10 100 1000 10000
Screen size (microns)
(a)
0
10
20
30
40
50
60
70
80
90
100
Ni
Elements
+106 μm -106+75 μm -75+63 μm
-63+38 μm -38 μm
(b)
Figure 1. The percentage of (a) the particle size distribution (b) Ni in the different particle sizes of the rougher tailings
Table 4. The characteristics of the granular activated carbon
Property Value
Iodine number, mg/gm 1100–1200
Apparent density, lb/ft3 29–31
U.S. standard sieve size (Mesh size) 4 × 8
Butane number, %w/w 23.5 (60 CTC)
Hardness, min. (ASTM D-3802) 98
Total surface area (BET), m2/gm 1150–1250
Ash, max (ASTM D-2866) 3%
Cumulative
percent
passing
(%)Sizedeportment(%)