3466 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
Compared with individual PEO, the flocs by ferric/PEO
were smaller but much larger than that of ferric alone. It
is also noted that by adding TA before ferric/PEO, the floc
size did not change obviously if not increased slightly.
Figure 6 indicates the sedimentation test of oil sands
tailing slurry with and without adding tannic acid over
eighteen hours of free settling time. The variation in the
height of mudlines is shown in the lower diagram. As can
be seen, the control group of tailing slurry (left graduated
cylinder) without any chemical addition behaved with high
colloidal stability when, and no clear mudline appeared
even after 2 hours of settling. The slurry treated by ferric/
PEO always had lower mudline than that by TA and fer-
ric/PEO. Since FBRM has indicated the similar floc size
distributions of these two chemical schemes, it implies
that flocs formed by ferric/PEO were more compressible.
In other words, the TA treatment increased the compres-
sion resistance of flocs. It is obvious that within the first
hour of settling, the mudline for ferric/PEO treated tail-
ings experienced a dramatic decline compared to when the
TA was used. Correspondingly, the sediment volume also
decreased more for ferric/PEO treated tailings. After the
long settling time of eighteen hours, the TA-treated tail-
ings still had a larger sediment volume (276 mL) versus
the tailings without TA (238 mL). On the micro-scale, we
guess that the presence of TA may offer supporting effects
(enhanced rigidity) within the flocs so that the sediment
structure reluctant to be yieldable. Consequently, the tiny
water channels or pores were also not easy to close and seal
the water inside flocs. Overall, the increase in compression
resistance of flocs brought by TA exerted positive effects on
pressure filtration.
Shear Stress Measurement
Figure 7 shows the shear stress of tailing slurry with and
without TA. The measurements were carried out with
continuous and constant shear rate ramps in a concentric
cylinder. As can be seen, the shear stress increased with
increasing shear rate from 10 to 100 s–1. The tailings slurry
treated with TA behaved with higher shear stress compared
with the slurry conditioned by ferric/PEO, which was also
the case at a constant shear rate of 50 s–1. The results proved
that stronger aggregates were generated when the tailing
slurry was conditioned with three chemicals. We believe
that the improvement in floc strength was beneficial for
pressure filtration.
Elemental Analysis and UV-Vis Spectra
The role of tannic acid in the flocculation filtration pro-
cess was investigated. Table 1 shows the elemental analysis
of the solid surface in tailing slurry before and after con-
ditioning with TA. Without chemical addition, it can be
seen that the solid in the tailings contained ca. 9.6% car-
bon and other elements. These elements were associated
with the contamination of residue bitumen in the tailings
[19]. If we pay attention to the surface carbon content,
which was seen to increase after conditioning with TA,
representing the adsorption of TA on the solid surface. As
Figure 5. FBRM measurement of un-weighted and square-weighed chord length distribution of 0.1 wt% tailing slurry under
different chemical conditioning. The data were acquired after 5 min following the addition of chemicals. Stirring speed
300 rpm
Compared with individual PEO, the flocs by ferric/PEO
were smaller but much larger than that of ferric alone. It
is also noted that by adding TA before ferric/PEO, the floc
size did not change obviously if not increased slightly.
Figure 6 indicates the sedimentation test of oil sands
tailing slurry with and without adding tannic acid over
eighteen hours of free settling time. The variation in the
height of mudlines is shown in the lower diagram. As can
be seen, the control group of tailing slurry (left graduated
cylinder) without any chemical addition behaved with high
colloidal stability when, and no clear mudline appeared
even after 2 hours of settling. The slurry treated by ferric/
PEO always had lower mudline than that by TA and fer-
ric/PEO. Since FBRM has indicated the similar floc size
distributions of these two chemical schemes, it implies
that flocs formed by ferric/PEO were more compressible.
In other words, the TA treatment increased the compres-
sion resistance of flocs. It is obvious that within the first
hour of settling, the mudline for ferric/PEO treated tail-
ings experienced a dramatic decline compared to when the
TA was used. Correspondingly, the sediment volume also
decreased more for ferric/PEO treated tailings. After the
long settling time of eighteen hours, the TA-treated tail-
ings still had a larger sediment volume (276 mL) versus
the tailings without TA (238 mL). On the micro-scale, we
guess that the presence of TA may offer supporting effects
(enhanced rigidity) within the flocs so that the sediment
structure reluctant to be yieldable. Consequently, the tiny
water channels or pores were also not easy to close and seal
the water inside flocs. Overall, the increase in compression
resistance of flocs brought by TA exerted positive effects on
pressure filtration.
Shear Stress Measurement
Figure 7 shows the shear stress of tailing slurry with and
without TA. The measurements were carried out with
continuous and constant shear rate ramps in a concentric
cylinder. As can be seen, the shear stress increased with
increasing shear rate from 10 to 100 s–1. The tailings slurry
treated with TA behaved with higher shear stress compared
with the slurry conditioned by ferric/PEO, which was also
the case at a constant shear rate of 50 s–1. The results proved
that stronger aggregates were generated when the tailing
slurry was conditioned with three chemicals. We believe
that the improvement in floc strength was beneficial for
pressure filtration.
Elemental Analysis and UV-Vis Spectra
The role of tannic acid in the flocculation filtration pro-
cess was investigated. Table 1 shows the elemental analysis
of the solid surface in tailing slurry before and after con-
ditioning with TA. Without chemical addition, it can be
seen that the solid in the tailings contained ca. 9.6% car-
bon and other elements. These elements were associated
with the contamination of residue bitumen in the tailings
[19]. If we pay attention to the surface carbon content,
which was seen to increase after conditioning with TA,
representing the adsorption of TA on the solid surface. As
Figure 5. FBRM measurement of un-weighted and square-weighed chord length distribution of 0.1 wt% tailing slurry under
different chemical conditioning. The data were acquired after 5 min following the addition of chemicals. Stirring speed
300 rpm