1180 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
hydration layer compared to scheelite. Consequently, this
leads to poorer flotation performance.
The Development of a New, Enhanced Collector
To tackle the slow flotation rates of wolframite and cassit-
erite, the initial consideration involves the optimization of
the collector to enhance their collecting. Herein, the methyl
group, serving as an electron-donating moiety, is intro-
duced into the ortho position of benzo hydroxamic acid.
When the electron-repulsive effect of the methyl group
is transferred along the benzene ring, there is an alternat-
ing phenomenon of positive and negative electrons in the
benzene ring[14]. The ortho-position and para-position of
the methyl group have higher electron density, while the
meso-position electron cloud density is lower. Therefore,
the electro-cloud density of oxime on the ortho-position
increases, further strengthening the electron-accepting
ability of Pb in Pb-MBHA structure. The LUMO energy
serves as a gauge for assessing the capacity towards acquir-
ing electrons. Previous research has determined the chemi-
cal formula of Pb-BHA as Pb4L5(OH)3 through X-ray
single-crystal diffraction and obtained its optimized stable
configuration[21]. The LUMO energy of the stable con-
figurations of Pb-BHA and Pb-MBHA has been calculated
here, as shown in Figure 10. The lower LUMO energy of
Pb-MBHA(–0.05408 a.u.) than Pb-BHA(–0.04568 a.u.)
indicates that it is easier to get electrons and is more active
during the adsorption reaction with oxygen atoms on min-
eral surfaces, which is consistent with our hypothesis.
To verify the flotation performance of Pb-MBHA for
tungsten-tin minerals, the recovery of scheelite, wolframite,
cassiterite, calcite, and fluorite was investigated, in which
calcite and fluorite as common gangue minerals in actual
tungsten-tin ores. As shown in Figure 11, compared with
Pb-BHA, the recovery of all five minerals increases under
the Pb-MBHA collector, especially for wolframite and cas-
siterite. This indicated that Pb-MBHA has a greater ability
to collect wolframite and cassiterite. The recovery of wol-
framite and cassiterite increased from 75.4% and 53.9%
to 90.24% and 84.2%, respectively. Neither Pb-BHA nor
Pb-MBHA possesses the capability to capture fluorite, as
both complexing collectors, Pb-BHA and Pb-MBHA, uti-
lize lead ion group to interact with the oxygen sites, thus
exhibiting excellent selectivity. However, the Pb-MBHA
has higher recovery for calcite, which needs to be consid-
ered in practical applications.
The New-Process Flotation Experiment
Based on the study of flotation behavior and flotation rate
of tungsten-tin single minerals, the closed-circuit flota-
tion experiment was conducted according to the flowsheet
shown in Figure 12. The principal flow of Tungsten-tin is
a asynchronous flotation. The main process adopts a lower
pH (pH=8.2±0.2), which is conducive to the flotation of
scheelite with a fast flotation rate and produces high-grade
scheelite concentrate. Tungsten-tin minerals with slow flo-
tation rate (wolframite and cassiterite), fall into the tailings
of the main process because they cannot enter the concen-
trate of the main process. The secondary process adopts a
Figure 9. The schematic view about influence of different hydration degrees on the Pb-BHA adsorption
hydration layer compared to scheelite. Consequently, this
leads to poorer flotation performance.
The Development of a New, Enhanced Collector
To tackle the slow flotation rates of wolframite and cassit-
erite, the initial consideration involves the optimization of
the collector to enhance their collecting. Herein, the methyl
group, serving as an electron-donating moiety, is intro-
duced into the ortho position of benzo hydroxamic acid.
When the electron-repulsive effect of the methyl group
is transferred along the benzene ring, there is an alternat-
ing phenomenon of positive and negative electrons in the
benzene ring[14]. The ortho-position and para-position of
the methyl group have higher electron density, while the
meso-position electron cloud density is lower. Therefore,
the electro-cloud density of oxime on the ortho-position
increases, further strengthening the electron-accepting
ability of Pb in Pb-MBHA structure. The LUMO energy
serves as a gauge for assessing the capacity towards acquir-
ing electrons. Previous research has determined the chemi-
cal formula of Pb-BHA as Pb4L5(OH)3 through X-ray
single-crystal diffraction and obtained its optimized stable
configuration[21]. The LUMO energy of the stable con-
figurations of Pb-BHA and Pb-MBHA has been calculated
here, as shown in Figure 10. The lower LUMO energy of
Pb-MBHA(–0.05408 a.u.) than Pb-BHA(–0.04568 a.u.)
indicates that it is easier to get electrons and is more active
during the adsorption reaction with oxygen atoms on min-
eral surfaces, which is consistent with our hypothesis.
To verify the flotation performance of Pb-MBHA for
tungsten-tin minerals, the recovery of scheelite, wolframite,
cassiterite, calcite, and fluorite was investigated, in which
calcite and fluorite as common gangue minerals in actual
tungsten-tin ores. As shown in Figure 11, compared with
Pb-BHA, the recovery of all five minerals increases under
the Pb-MBHA collector, especially for wolframite and cas-
siterite. This indicated that Pb-MBHA has a greater ability
to collect wolframite and cassiterite. The recovery of wol-
framite and cassiterite increased from 75.4% and 53.9%
to 90.24% and 84.2%, respectively. Neither Pb-BHA nor
Pb-MBHA possesses the capability to capture fluorite, as
both complexing collectors, Pb-BHA and Pb-MBHA, uti-
lize lead ion group to interact with the oxygen sites, thus
exhibiting excellent selectivity. However, the Pb-MBHA
has higher recovery for calcite, which needs to be consid-
ered in practical applications.
The New-Process Flotation Experiment
Based on the study of flotation behavior and flotation rate
of tungsten-tin single minerals, the closed-circuit flota-
tion experiment was conducted according to the flowsheet
shown in Figure 12. The principal flow of Tungsten-tin is
a asynchronous flotation. The main process adopts a lower
pH (pH=8.2±0.2), which is conducive to the flotation of
scheelite with a fast flotation rate and produces high-grade
scheelite concentrate. Tungsten-tin minerals with slow flo-
tation rate (wolframite and cassiterite), fall into the tailings
of the main process because they cannot enter the concen-
trate of the main process. The secondary process adopts a
Figure 9. The schematic view about influence of different hydration degrees on the Pb-BHA adsorption