XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 703
a need to understand the effect of these different chained
collectors under different water qualities further.
MATERIALS AND METHODS FACTORIAL
DESIGN OF EXPERIMENTS
The experiments for the study were conducted in two
phases to investigate two collectors of different chain
lengths. Phase 1 utilised a two-chained collector, sodium
ethyl-xanthate (SEX). For Phase 2, a four-chained collector,
sodium isobutyl-xanthate (SIBX) was selected. The factors
selected are the ionic strength of the water and the dosage
of the collectors. Three levels for each factor, i.e., high, low,
and medium were selected. Therefore, with a 32 factorial
design, there were 9 experimental conditions for each phase
as shown in Table 1.
BENCH SCALE FLOTATION
A sample of a Merensky ore was obtained from the Bushveld
Igneous Complex (BIC) of South Africa. Once the bulk
sample was crushed and split into 1 kg ore samples, the ore
was milled in the prepared plant water at the required ionic
strength. This formed a slurry containing a solids’ grind
size of 60% passing 75µm. The slurry was added to a 3 L
Barker batch cell, and plant water was added to form a pulp
density of 35% solids. Air was then bubbled through the
pulp at 7 L/min as it was agitated by an impeller rotating
at 1200 rpm. Depramin 267 (depressant) and DowFroth
200 (frother) were then added at dosages of 100 g/t and
40 g/t respectively. After a certain conditioning time, the
froth was collected at multiple time intervals. The concen-
trate, tails and feed were sent for X-ray fluorescence analysis
(XRF). The results from the XRF analysis were then uti-
lized to calculate the grade and recoveries of copper and
nickel obtained in the experiments. This indicated the flo-
tation performance under different conditions, which was
the standard Merensky ore flotation procedure used at the
Centre for Minerals Research. To simulate the recycled pro-
cess water, synthetic plant water (SPW) was utilized with
0 SPW being represented by tap water. 40 L of 1 SPW
was prepared by the addition of inorganic salts to distilled
water. 3 and 5 SPW were synthesized by multiplying the
concentrations of the salts in 1 SPW by 3 and 5 respectively
(Wiese et al., 2005 Manono et al., 2018).
RESULTS EFFECT OF WATER QUALITY
AND COLLECTOR CHAIN-LENGTH ON
SOLIDS AND WATER RECOVERIES
Figure 1 shows the final solids and water recovered at the
three ionic strengths for SIBX and SEX at a dosage of 50,
100 and 150 g/t. Both collectors showed an increase in sol-
ids and water recoveries with an increase in ionic strength
from 0 to 3 SPW. At 0 SPW, SEX recovered 33% more sol-
ids than SIBX. However, SIBX at the higher ionic strengths
recovered more solids than SEX. At 50 g/t, the difference
in the performance of the two collectors decreased as the
ionic strength of the water increased. The difference in sol-
ids recovered at 0 SPW further decreased to 8% at 3 SPW,
and finally, 3% at 5 SPW. The water recoveries increased
with an increase in the ionic strength of the water. At 0
and 5 SPW, SIBX recovered less water than SEX. However,
at 3 SPW, SEX recovered 20% less water than SIBX. At 0
SPW, increasing collector dosage improved both solid and
water recoveries for both collectors. However, at 3 SPW, the
impact on recoveries with increasing dosage was minimal
for both collectors. At 5 SPW, SIBX showed little change
in recoveries, while SEX displayed a decrease in recoveries
with higher collector dosage.
At 100 g/t the lowest solids and water recoveries
occurred with SIBX at 0 SPW. As the ionic strength of
the water increased, the solids recoveries for both collec-
tors increased as well. As observed at a collector dosage of
50 g/t, solids recoveries with SIBX at 3 and 5 SPW were
higher than solids recoveries with SEX. Unlike at the 50
g/t dosage however, the difference between the collec-
tor performance did not decrease with an increase in the
ionic strength of the water. The water recoveries for SIBX
increased with an increase in ionic strength. Aside from 0
SPW, SIBX had higher water recovered than SEX. SEX had
an increase in the water recovered when the synthetic plant
water strength was increased from 0 to 3 SPW. However,
at 5 SPW, there was a 15% decrease in the water recovered
by SEX in comparison to 3 SPW. At 150 g/t as the ionic
strength of the water increased, the solids and water recov-
eries increased as observed for the lower dosages. However,
for SEX at 5 SPW, there is a decrease in both the water
and solids recoveries. Therefore, as observed at 100 g/t,
the highest water and solids recoveries observed for SEX
occurred at 3 SPW. Another difference observed is at this
higher dosage, SIBX and SEX had similar solids and water
recoveries at 0 SPW in comparison to lower dosages, where
Table 1. Phases, factors, and levels selected for the study
Phase 1 SEX Phase 2 SIBX
Factor SPW Collector Dosage, g/t
High level 5 150
Medium level 3 50
Low level 0 0
a need to understand the effect of these different chained
collectors under different water qualities further.
MATERIALS AND METHODS FACTORIAL
DESIGN OF EXPERIMENTS
The experiments for the study were conducted in two
phases to investigate two collectors of different chain
lengths. Phase 1 utilised a two-chained collector, sodium
ethyl-xanthate (SEX). For Phase 2, a four-chained collector,
sodium isobutyl-xanthate (SIBX) was selected. The factors
selected are the ionic strength of the water and the dosage
of the collectors. Three levels for each factor, i.e., high, low,
and medium were selected. Therefore, with a 32 factorial
design, there were 9 experimental conditions for each phase
as shown in Table 1.
BENCH SCALE FLOTATION
A sample of a Merensky ore was obtained from the Bushveld
Igneous Complex (BIC) of South Africa. Once the bulk
sample was crushed and split into 1 kg ore samples, the ore
was milled in the prepared plant water at the required ionic
strength. This formed a slurry containing a solids’ grind
size of 60% passing 75µm. The slurry was added to a 3 L
Barker batch cell, and plant water was added to form a pulp
density of 35% solids. Air was then bubbled through the
pulp at 7 L/min as it was agitated by an impeller rotating
at 1200 rpm. Depramin 267 (depressant) and DowFroth
200 (frother) were then added at dosages of 100 g/t and
40 g/t respectively. After a certain conditioning time, the
froth was collected at multiple time intervals. The concen-
trate, tails and feed were sent for X-ray fluorescence analysis
(XRF). The results from the XRF analysis were then uti-
lized to calculate the grade and recoveries of copper and
nickel obtained in the experiments. This indicated the flo-
tation performance under different conditions, which was
the standard Merensky ore flotation procedure used at the
Centre for Minerals Research. To simulate the recycled pro-
cess water, synthetic plant water (SPW) was utilized with
0 SPW being represented by tap water. 40 L of 1 SPW
was prepared by the addition of inorganic salts to distilled
water. 3 and 5 SPW were synthesized by multiplying the
concentrations of the salts in 1 SPW by 3 and 5 respectively
(Wiese et al., 2005 Manono et al., 2018).
RESULTS EFFECT OF WATER QUALITY
AND COLLECTOR CHAIN-LENGTH ON
SOLIDS AND WATER RECOVERIES
Figure 1 shows the final solids and water recovered at the
three ionic strengths for SIBX and SEX at a dosage of 50,
100 and 150 g/t. Both collectors showed an increase in sol-
ids and water recoveries with an increase in ionic strength
from 0 to 3 SPW. At 0 SPW, SEX recovered 33% more sol-
ids than SIBX. However, SIBX at the higher ionic strengths
recovered more solids than SEX. At 50 g/t, the difference
in the performance of the two collectors decreased as the
ionic strength of the water increased. The difference in sol-
ids recovered at 0 SPW further decreased to 8% at 3 SPW,
and finally, 3% at 5 SPW. The water recoveries increased
with an increase in the ionic strength of the water. At 0
and 5 SPW, SIBX recovered less water than SEX. However,
at 3 SPW, SEX recovered 20% less water than SIBX. At 0
SPW, increasing collector dosage improved both solid and
water recoveries for both collectors. However, at 3 SPW, the
impact on recoveries with increasing dosage was minimal
for both collectors. At 5 SPW, SIBX showed little change
in recoveries, while SEX displayed a decrease in recoveries
with higher collector dosage.
At 100 g/t the lowest solids and water recoveries
occurred with SIBX at 0 SPW. As the ionic strength of
the water increased, the solids recoveries for both collec-
tors increased as well. As observed at a collector dosage of
50 g/t, solids recoveries with SIBX at 3 and 5 SPW were
higher than solids recoveries with SEX. Unlike at the 50
g/t dosage however, the difference between the collec-
tor performance did not decrease with an increase in the
ionic strength of the water. The water recoveries for SIBX
increased with an increase in ionic strength. Aside from 0
SPW, SIBX had higher water recovered than SEX. SEX had
an increase in the water recovered when the synthetic plant
water strength was increased from 0 to 3 SPW. However,
at 5 SPW, there was a 15% decrease in the water recovered
by SEX in comparison to 3 SPW. At 150 g/t as the ionic
strength of the water increased, the solids and water recov-
eries increased as observed for the lower dosages. However,
for SEX at 5 SPW, there is a decrease in both the water
and solids recoveries. Therefore, as observed at 100 g/t,
the highest water and solids recoveries observed for SEX
occurred at 3 SPW. Another difference observed is at this
higher dosage, SIBX and SEX had similar solids and water
recoveries at 0 SPW in comparison to lower dosages, where
Table 1. Phases, factors, and levels selected for the study
Phase 1 SEX Phase 2 SIBX
Factor SPW Collector Dosage, g/t
High level 5 150
Medium level 3 50
Low level 0 0