3300 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
out to correspond with the five parameters specified for the
CCD. It is important to note that the catalyst type was a
categorical factor. The parameter levels and values are high-
lighted in Table 1, in addition the leaching recovery of Ni.
Per the experimental design (as highlighted in Table 2), the
leaching experiments were conducted in a random order to
minimize the effect of systematic errors (Owusu, Mends,
and Acquah 2022). The Minitab software (version 21.4.2)
was used for the design of experiments, and the succeeding
regression and graphical analysis of the obtained leaching
results.
Experimental Procedure
The leaching experiments for each run (in Table 2) were
conducted in the water bath with 5 g of the ground sample
pulped with 100 mL of the leach solution, with parameters
including temperature, time, H2SO4 concentration, cata-
lyst type and concentration varied. The slurry was agitated
in the water bath at about 200 rev/min. The leach solution
was sampled at set intervals and filtered using the centri-
fuge for chemical analysis by the ICP-OES technique. The
leaching recoveries of Ni were computed using the formu-
lar shown in Eq. (1).
R Ff
Cc 100% #=(1)
where,
R =The leaching recovery of Ni (%).
C =The volume of leach liquor (mL).
c =The concentration of each metal in the leach liquor
(mg/L).
F =The mass of the feed sample (g).
f =The concentration of each metal in the feed sample
(mg/L).
Characterization
The characterization studies were performed using the
ground sample. The cumulative percent passing of the sam-
ple was first validated using a particle size analyzer. Using
a set of sieves, the size-by-size deportment of the valuable
minerals in the rougher tailings was also evaluated. The
elemental composition of the feed material and the oversize
from each sieve size was examined using the acid digestion
method. Thus, the samples were completely dissolved in
freshly prepared aqua regia for one hour at 250 °C. The
resulting digests were filtered, diluted, and analyzed using
the ICP-OES. The crystal structures and mineral constit-
uents of the feed sample were characterized by the X-ray
diffraction (XRD) with Cu Kα radiation. The morphology
was analyzed by the scanning electron microscopy (SEM),
Table 1. The coded parameter levels and values used in the experimental design
Parameter Units Symbols
Coded Variables and Levels
–1 0 +1
H2SO4 conc. M m1 1 2.5 4
Catalyst dosage g/L m
2 0 10 20
Leaching temperature °C m
3 20 50 80
Leaching time h m4 4 8 12
Catalyst type – m5 FeCl3 AC
Table 2. The layout of the experimental design
Standard Order Run
H
2 SO
4 Concentration, (M)
Catalyst Dosage
(g/L)
Leaching
Temperature (°C)
Leaching Time
(h) Catalyst Type
57 1 2.5 10 50 8 AC
12 2 4.0 20 20 12 FeCl3
42 3 1.0 20 20 12 AC
62 4 2.5 10 50 8 AC
37 5 4.0 0 80 4 AC
58 6 2.5 10 50 8 AC
35 7 4.0 20 20 4 AC
47 8 4.0 20 80 12 AC
60 9 2.5 10 50 8 AC
17 10 1.0 10 50 8 FeCl3
59 11 2.5 10 50 8 AC
10 12 4.0 0 20 12 FeCl
3
out to correspond with the five parameters specified for the
CCD. It is important to note that the catalyst type was a
categorical factor. The parameter levels and values are high-
lighted in Table 1, in addition the leaching recovery of Ni.
Per the experimental design (as highlighted in Table 2), the
leaching experiments were conducted in a random order to
minimize the effect of systematic errors (Owusu, Mends,
and Acquah 2022). The Minitab software (version 21.4.2)
was used for the design of experiments, and the succeeding
regression and graphical analysis of the obtained leaching
results.
Experimental Procedure
The leaching experiments for each run (in Table 2) were
conducted in the water bath with 5 g of the ground sample
pulped with 100 mL of the leach solution, with parameters
including temperature, time, H2SO4 concentration, cata-
lyst type and concentration varied. The slurry was agitated
in the water bath at about 200 rev/min. The leach solution
was sampled at set intervals and filtered using the centri-
fuge for chemical analysis by the ICP-OES technique. The
leaching recoveries of Ni were computed using the formu-
lar shown in Eq. (1).
R Ff
Cc 100% #=(1)
where,
R =The leaching recovery of Ni (%).
C =The volume of leach liquor (mL).
c =The concentration of each metal in the leach liquor
(mg/L).
F =The mass of the feed sample (g).
f =The concentration of each metal in the feed sample
(mg/L).
Characterization
The characterization studies were performed using the
ground sample. The cumulative percent passing of the sam-
ple was first validated using a particle size analyzer. Using
a set of sieves, the size-by-size deportment of the valuable
minerals in the rougher tailings was also evaluated. The
elemental composition of the feed material and the oversize
from each sieve size was examined using the acid digestion
method. Thus, the samples were completely dissolved in
freshly prepared aqua regia for one hour at 250 °C. The
resulting digests were filtered, diluted, and analyzed using
the ICP-OES. The crystal structures and mineral constit-
uents of the feed sample were characterized by the X-ray
diffraction (XRD) with Cu Kα radiation. The morphology
was analyzed by the scanning electron microscopy (SEM),
Table 1. The coded parameter levels and values used in the experimental design
Parameter Units Symbols
Coded Variables and Levels
–1 0 +1
H2SO4 conc. M m1 1 2.5 4
Catalyst dosage g/L m
2 0 10 20
Leaching temperature °C m
3 20 50 80
Leaching time h m4 4 8 12
Catalyst type – m5 FeCl3 AC
Table 2. The layout of the experimental design
Standard Order Run
H
2 SO
4 Concentration, (M)
Catalyst Dosage
(g/L)
Leaching
Temperature (°C)
Leaching Time
(h) Catalyst Type
57 1 2.5 10 50 8 AC
12 2 4.0 20 20 12 FeCl3
42 3 1.0 20 20 12 AC
62 4 2.5 10 50 8 AC
37 5 4.0 0 80 4 AC
58 6 2.5 10 50 8 AC
35 7 4.0 20 20 4 AC
47 8 4.0 20 80 12 AC
60 9 2.5 10 50 8 AC
17 10 1.0 10 50 8 FeCl3
59 11 2.5 10 50 8 AC
10 12 4.0 0 20 12 FeCl
3