2240 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
decreases with the increase of pH, reaching a peak at pH=7
and then gradually decreasing. The overall recovery of fine-
grained lepidolite was increased in both cases under the
effect of NBs, and the recovery of fine-grained lepidolite
increased from 65.45% to 70.16% at pH=7. Figure 5 illus-
trates the variation of the recovery of fine-grained lepidolite
with the concentration of collector in both cases. The flota-
tion recovery of fine-grained lepidolite gradually increased
with an increase in the concentration of the collector. At a
collector dosage of 70 mg/L, the flotation recovery of fine-
grained lepidolite reached 65.45%, after which there was no
further increase. It is clear that the addition of NB improves
the recovery of fine-grained lepidolite and also reduces the
dosage of collector. This results in higher flotation recover-
ies being obtained at lower collector concentrations in the
presence of NB compared to no NB addition. It is expected
that the collector concentration will be reduced by approxi-
mately 10 mg/L.
Characteristics of NBs
Figure 6 shows the effect of pH on the average size of NBs
and the changes in the average size of NBs under different
reagent conditions. According to the changes in the size
of NBs under different reagent conditions, it can be seen
that the average sizes of NBs all increased after the addi-
tion of collector, and the size of NBs increased the least
after the addition of the cationic collector DDA, followed
by the anionic collector HQ330, and the average size of
NBs was the largest after the addition of the mixed collec-
tor of HQ330 and DDA. This may be because the addi-
tion of the collector, also known as a surfactant, promoted
the nucleation of NBs and increased the accumulation of
their surface charge, thereby improving their stability. The
surfactant also lowered the surface tension of the solution,
resulting in the gradual growth of the NBs and an increase
in their size.[7–9]
In addition, with the increase of pH, the average size
of NBs increases and then decreases, and when pH=5, the
average size of NBs reaches the maximum value, and when
pH is greater than 7, the average size of NBs decreases rap-
idly. It can be seen that pH has a strong influence on the
size of NBs, and pH between 4 and 5 is the isoelectric point
(IEP) of NBs, and the size of NBs reaches its maximum at
the IEP. This may be related to the change in zeta potential,
which increases with pH. According to the ionic stability
theory, the electrostatic pressure generated by the charge
around the NBs balances the internal Laplace pressure,
which prevents the diffusion of gases into the environment,
resulting in smaller NBs under acidic and alkaline condi-
tions and larger NBs near the IEP.[19, 20]
Effect of NBs on the flocculation of fine lepidolites
Figure 7 shows the particle size analysis of lepidolite par-
ticles in UP water and NBs water in non-stirred condition,
40 50 60 70 80 90 100
20
30
40
50
60
70
80
Reagent concentration, mg·L -1
UP water
NBs water
(pH=7)
Figure 5. Effect of reagent concentration on the flotation of fine lepidolite with NBs
Recovery%
,
decreases with the increase of pH, reaching a peak at pH=7
and then gradually decreasing. The overall recovery of fine-
grained lepidolite was increased in both cases under the
effect of NBs, and the recovery of fine-grained lepidolite
increased from 65.45% to 70.16% at pH=7. Figure 5 illus-
trates the variation of the recovery of fine-grained lepidolite
with the concentration of collector in both cases. The flota-
tion recovery of fine-grained lepidolite gradually increased
with an increase in the concentration of the collector. At a
collector dosage of 70 mg/L, the flotation recovery of fine-
grained lepidolite reached 65.45%, after which there was no
further increase. It is clear that the addition of NB improves
the recovery of fine-grained lepidolite and also reduces the
dosage of collector. This results in higher flotation recover-
ies being obtained at lower collector concentrations in the
presence of NB compared to no NB addition. It is expected
that the collector concentration will be reduced by approxi-
mately 10 mg/L.
Characteristics of NBs
Figure 6 shows the effect of pH on the average size of NBs
and the changes in the average size of NBs under different
reagent conditions. According to the changes in the size
of NBs under different reagent conditions, it can be seen
that the average sizes of NBs all increased after the addi-
tion of collector, and the size of NBs increased the least
after the addition of the cationic collector DDA, followed
by the anionic collector HQ330, and the average size of
NBs was the largest after the addition of the mixed collec-
tor of HQ330 and DDA. This may be because the addi-
tion of the collector, also known as a surfactant, promoted
the nucleation of NBs and increased the accumulation of
their surface charge, thereby improving their stability. The
surfactant also lowered the surface tension of the solution,
resulting in the gradual growth of the NBs and an increase
in their size.[7–9]
In addition, with the increase of pH, the average size
of NBs increases and then decreases, and when pH=5, the
average size of NBs reaches the maximum value, and when
pH is greater than 7, the average size of NBs decreases rap-
idly. It can be seen that pH has a strong influence on the
size of NBs, and pH between 4 and 5 is the isoelectric point
(IEP) of NBs, and the size of NBs reaches its maximum at
the IEP. This may be related to the change in zeta potential,
which increases with pH. According to the ionic stability
theory, the electrostatic pressure generated by the charge
around the NBs balances the internal Laplace pressure,
which prevents the diffusion of gases into the environment,
resulting in smaller NBs under acidic and alkaline condi-
tions and larger NBs near the IEP.[19, 20]
Effect of NBs on the flocculation of fine lepidolites
Figure 7 shows the particle size analysis of lepidolite par-
ticles in UP water and NBs water in non-stirred condition,
40 50 60 70 80 90 100
20
30
40
50
60
70
80
Reagent concentration, mg·L -1
UP water
NBs water
(pH=7)
Figure 5. Effect of reagent concentration on the flotation of fine lepidolite with NBs
Recovery%
,