2422 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
This measurement was taken within 6 min after the emulsi-
fication process. The results indicate that the average drop-
let size of the emulsion is close to 10 µm as estimated. In
addition, more than 80% of the droplets have sizes below
20 µm as shown in Figure 1. The droplet size distribution
of an emulsion is an important factor that affects its stabil-
ity. The smaller the droplet size distribution of an emulsion,
the higher the stability of the emulsion. The emulsion must
be stable for a reasonable length of time to facilitate mixing
and attachment and to be suitable for coarse particle recov-
ery through froth flotation. The zeta potential and conduc-
tivity of the emulsion measured with the ZetaProbe analysis
are reported in Table 5. The negative sign of the emulsion
zeta potential is because the PAX is an anionic surfactant.
The creaming rate and oil separation of the kerosene-
in-water emulsion samples with and without PAX were
observed for 100 h. The behaviors of the emulsion without
PAX after 5 min, 1 h, and 10 h are provided in Figure 2.
Similarly, the behaviors of the emulsion after 10, 50, and
100 h are provided in Figures 3 and 4. As shown by the
change in cream and oil height, the emulsion is undergoing
creaming and oil separation, implying that there is a phase
separation of the emulsion with time. After 100 h, there
was almost a complete phase separation of the emulsion
into water and oil. Although these emulsions are not very
stable, they are more stable than emulsions produced from
kerosene in water without any PAX as a stabilizer which
separates within 5 min (see Figures 2 and 3).
GRIND CALIBRATION CURVE
The feed sample (0 min), 3 min, and 5 min grind samples
were sized manually with sieves because they contain mainly
coarse particles, while the Mastersizer 3000 was used to size
the 10 min, 15 min, 20 min, and 30 min grind samples due
to the predominance of fine particles.
The cumulative passing size distributions of the sam-
ples are provided in Figure 5, and the P80 values of the
samples for each grinding time are reported in Figure 6.
The 3 min and 5 min grinds produced samples with a P50
of 164 µm and 97 µm respectively. As the aim of the study
was to investigate the impact on coarse particles, a grind
time of 5 min was used.
FLOTATION RESULTS
The flotation test was conducted on the 5-min grind sam-
ple. Table 6 shows the MLA results for the proportion of
particles in each size fraction that exhibits over 95% surface
liberation of chalcopyrite. This value increased with a reduc-
tion in particle size. The +150 μm fraction has the lowest
composition of nearly fully-liberated chalcopyrite particles
while the –45 μm has the highest proportion. this value
of the coarse fraction is significantly higher than expected,
showing that the ore sample is not finely disseminated. As
such, the grinding of the sample produced particles with
high surface liberation even at a relatively coarse product.
The flotation test with 60 g/t PAX as a conventional
collector failed to provide a stable froth, and recovery
Figure 1. The droplet size distribution of the kerosene-in-water emulsion with PAX
Table 5. The pH values, zeta potential, and conductivity of emulsion
System pH Zeta Potential, mV Conductivity, mS/cm
Emulsion 7.6 –48 0.60
This measurement was taken within 6 min after the emulsi-
fication process. The results indicate that the average drop-
let size of the emulsion is close to 10 µm as estimated. In
addition, more than 80% of the droplets have sizes below
20 µm as shown in Figure 1. The droplet size distribution
of an emulsion is an important factor that affects its stabil-
ity. The smaller the droplet size distribution of an emulsion,
the higher the stability of the emulsion. The emulsion must
be stable for a reasonable length of time to facilitate mixing
and attachment and to be suitable for coarse particle recov-
ery through froth flotation. The zeta potential and conduc-
tivity of the emulsion measured with the ZetaProbe analysis
are reported in Table 5. The negative sign of the emulsion
zeta potential is because the PAX is an anionic surfactant.
The creaming rate and oil separation of the kerosene-
in-water emulsion samples with and without PAX were
observed for 100 h. The behaviors of the emulsion without
PAX after 5 min, 1 h, and 10 h are provided in Figure 2.
Similarly, the behaviors of the emulsion after 10, 50, and
100 h are provided in Figures 3 and 4. As shown by the
change in cream and oil height, the emulsion is undergoing
creaming and oil separation, implying that there is a phase
separation of the emulsion with time. After 100 h, there
was almost a complete phase separation of the emulsion
into water and oil. Although these emulsions are not very
stable, they are more stable than emulsions produced from
kerosene in water without any PAX as a stabilizer which
separates within 5 min (see Figures 2 and 3).
GRIND CALIBRATION CURVE
The feed sample (0 min), 3 min, and 5 min grind samples
were sized manually with sieves because they contain mainly
coarse particles, while the Mastersizer 3000 was used to size
the 10 min, 15 min, 20 min, and 30 min grind samples due
to the predominance of fine particles.
The cumulative passing size distributions of the sam-
ples are provided in Figure 5, and the P80 values of the
samples for each grinding time are reported in Figure 6.
The 3 min and 5 min grinds produced samples with a P50
of 164 µm and 97 µm respectively. As the aim of the study
was to investigate the impact on coarse particles, a grind
time of 5 min was used.
FLOTATION RESULTS
The flotation test was conducted on the 5-min grind sam-
ple. Table 6 shows the MLA results for the proportion of
particles in each size fraction that exhibits over 95% surface
liberation of chalcopyrite. This value increased with a reduc-
tion in particle size. The +150 μm fraction has the lowest
composition of nearly fully-liberated chalcopyrite particles
while the –45 μm has the highest proportion. this value
of the coarse fraction is significantly higher than expected,
showing that the ore sample is not finely disseminated. As
such, the grinding of the sample produced particles with
high surface liberation even at a relatively coarse product.
The flotation test with 60 g/t PAX as a conventional
collector failed to provide a stable froth, and recovery
Figure 1. The droplet size distribution of the kerosene-in-water emulsion with PAX
Table 5. The pH values, zeta potential, and conductivity of emulsion
System pH Zeta Potential, mV Conductivity, mS/cm
Emulsion 7.6 –48 0.60