Powder Technology 406 (2022) 117570
Contents lists available at ScienceDirect
Powder Technology
journal homepage: www.journals.elsevier.com/powder-technology
Effect of TIPA/TEA combined grinding aid on the behavior of quartz
flotation in DDA system
Yong Mao , Zehong Wang *, Wengang Liu , Pengcheng Tian
College of Resources and Civil Engineering, Northeastern University, Shenyang, Liaoning 110819, China
H I G H L I G H T S
G R A P H I C A L A B S T R A C T
• TIPA/TEA can significantly improve
grinding efficiency of quartz.
• TIPA/TEA combined grinding aid can
increase the recovery of quartz in DDA
system.
• Grinding aid and collector played a
synergistic role instead of competitive
adsorption.
• TIPA/TEA can promote the adsorption
of DDA.
A R T I C L E I N F O
A B S T R A C T
Keywords:
Combined grinding aid
TIPA/TEA
Quartz
Flotation
Adsorption
In this paper, different dosages of TIPA, TEA and their combined grinding aid were added to the process of quartz
grinding and their influence on the grinding efficiency and flotation recovery in DDA system was investigated.
From the grinding and flotation experiments, It can be known that the effect of the combined grinding aid was
better than that of a single reagent, which can not only significantly improve the grinding efficiency of quartz,
but also increase the recovery of quartz from flotation. Based on the results of FT-IR spectroscopy, XPS analysis,
quantum chemistry and solution chemistry calculations, it can be seen that the hydroxyl groups in the TIPA/TEA
combined grinding aid formed hydrogen bonds with O on the (101) surface of quartz, while collector DDA was
mainly electrostatically adsorbed on the surface of quartz with negative potential, and the introduction of
combined grinding aid improved the adsorption of DDA, the grinding aid and collector played a synergistic role
instead of competitive adsorption. The detection of contact angle and surface tension showed that the combined
grinding aid can improve the hydrophobicity of quartz, reduce the surface tension and CMC value of DDA, and
enhance the dispersibility of quartz, therefore, it can increase the recovery of quartz from flotation.
* Corresponding author.
E-mail address: wangzehong@mail.neu.edu.cn (Z. Wang).
https://doi.org/10.1016/j.powtec.2022.117570
Received 16 March 2022; Received in revised form 17 May 2022; Accepted 25 May 2022
Available online 30 May 2022
0032-5910/© 2022 Elsevier B.V. All rights reserved.
Y. Mao et al.
Powder Technology 406 (2022) 117570
1. Introduction
Without adding equipment or changing the existing production
processes, grinding aids were used to improve grinding efficiency and
reduce grinding energy consumption [1–3]. However, after the grinding
aids were added to the process of grinding, it is necessary to consider
their impact on subsequent sorting operations, especially flotation op­
erations [4]. As is well known, the flotation behavior of minerals was
mainly determined by their crystal structure, surface properties and pulp
properties, and these factors will be significantly affected by the
grinding process before the flotation operation [5]. From the perspective
of the grinding-flotation system, grinding was a complex physico­
chemical process, which will cause a series of changes in the surface
properties, crystal structure, particle size of minerals, and the chemistry
of the slurry solution, at the same time, it will also lead to a series of
problems, such as sludge cover caused by fine grinding, accelerated
oxidation of ground minerals, and a low grinding efficiency [6]. When
chemical grinding aids were added in the process of grinding, they will
definitely affect the surface properties of minerals and the properties of
the slurry, thereby affecting the flotation behavior of minerals. How­
ever, the influence of grinding aids on flotation operations was rarely
studied [7]. Therefore, further research on the influence of grinding aids
on the behavior of minerals flotation and broadening the application of
grinding aids in the field of mineral processing has important theoretical
and practical significance for adjusting the separation process conditions
and improving the separation efficiency and indicators.
Whether quartz was discarded as a gangue mineral or purified as a
raw material of non-metallic minerals, flotation was one of the effective
methods to collect it [8–10]. The current flotation reagents of quartz can
be divided into cationic collectors, anionic collectors and the anion/
cation mixed collectors [11]. DDA was used as a cation collector and had
a wide range of applications in the flotation system of quartz [12]. TIPA
and TEA, as common grinding aids, were widely used in the grinding of
cement and bauxite [13], but their influence on the grinding efficiency
and flotation behavior of quartz remains to be studied [14].
In this study, the influence of TIPA, TEA and their combined grinding
aids on the grinding efficiency of quartz was discussed. On this basis,
DDA was selected as a collector to study the effect of grinding aids on the
flotation behavior of quartz. A variety of detection and calculation
methods (FT-IR spectroscopy, XPS detection, quantum chemistry
calculation, solution chemistry calculation, contact angle and surface
tension detection) were used to reveal the influence mechanism of the
combined grinding aids on the flotation behavior of quartz. The research
results of this paper provide strong proof of the synergistic effect be­
tween grinding aids and flotation collectors, and lay the foundation for
the selection and application of grinding aids.
Fig. 1. Characteristic curve of particle size of material.
Fig. 2. X-ray diffraction of sample.
Table 1
X-ray fluorescence spectroscopy of sample.
2. Materials and methods
Element
SiO2
CaO
Al2O3
K2O
Na2O
MgO
TFe
Loss
Content /%
98.37
0.01
0.09
0.11
0.03
0.03
0.42
0.04
acid, HCl; Sodium hydroxide, NaOH, the reagents were all analytical and
were used without further purification.
2.1. Materials
2.1.1. Mineral samples
The raw quartz, tested in this research, was taken from Guangxi
Province, China. The sample with the size of less than 1.6 mm was ob­
tained after being crushed, hand-selected, ground, and sieved. The
particle size characteristic curve of the product was shown in Fig. 1. The
crystal phase structure of quartz and its chemical element components
were studied by using X-ray diffraction (XRD) and X-ray fluorescence
spectroscopy (XRF), the corresponding analysis results of the test ore
samples were shown in Fig. 2 and Table 1. It can be seen that the content
of SiO2 was 98.37% in the sample, indicating the high purity of quartz,
which can meet the requirements of the subsequent experiments.
2.2. Methods
2.2.1. Grinding test
A laboratory conical ball mill with a diameter of 150 × 50 mm and a
volume of 1 L produced in Hubei Province, China, was used for the
grinding test. The optimal grinding parameters of quartz without adding
grinding aids were conducted with a series of exploratory experiments,
in which, the grinding method was wet grinding, steel balls were
adopted as the grinding medium, aiming to reduce the grinding time and
maximize the effect of the grinding aids. The medium filling ratio (Ф)
was 50% (Volume ratio); the size of medium and the mass ratio was m
(Ф30 mm): m (Ф20 mm): m (Ф15 mm) = 30: 25: 45; the material-ball
ratio (Фm) was 0.8 (Volume ratio); the grinding concentration pulp
was 60% (Mass ratio); and the grinding time was 30 min. The supply of
quartz fed into the ball mill each time in the test was calculated by Eq.
2.1.2. Reagents
Triisopropanolamine (TIPA), [CH3CH(OH)CH2]3N; Triethanolamine
(TEA), C6H15NO3; Dodecylamine (DDA), CH3(CH2)11NH2; hydrochloric
2
Y. Mao et al.
Powder Technology 406 (2022) 117570
(1) [15]. The mineral sample with 243.20 g was added to the ball mill,
then 162.13 mL water was added, and finally an appropriate amount of
grinding aid solution was added (The mass of grinding aid accounts for
the percentage of the mass of quartz). After the grinding, the particle size
of the grinding products was analyzed by the standard inspection sieve
and vibrating sieve machine produced in Zhejiang Province, China, and
the grinding effect of the grinding aid was evaluated with the content of
− 0.043 mm particle size.
W = μVΦΦm Sm
2.2.5. Quantum chemistry calculation
Through the molecular dynamics simulation of the interaction be­
tween the mineral surface and the reagent, the nature of the reagent’s
effect on the mineral was explored, and the interaction between reagents
and minerals was provided at the molecular micro level, which could
deepen the understanding of the interaction between the reagents and
minerals and provide a theoretical basis for flotation. In this study, the
CASTEP module based on quantum mechanics calculations in the Ma­
terial studio 7.0 (MS) software was used to calculate the energy and
properties of the interaction system of minerals and reagents, and was
used to explore the effects of grinding aid molecules on the surface
properties of quartz, and the influence mechanism on the flotation
behavior [19].
(1)
Where W is the mass of the materials, g; μ is the ratio of the void
volume in the medium to the medium volume，when the grinding
medium was steel balls, the μ was calculated to be 0.38 (Volume ratio); V
is the effective volume of the mill, cm3; Ф is the ratio of the loose volume
of the grinding medium in the stationary state to the effective volume of
the mill, % (Volume ratio); Фm is the ratio of the loose volume of the
materials to the pore volume of the medium (Volume ratio); Sw is the
bulk density of the material, g/cm3.
2.2.6. Contact angle measurement
The XG-CMAB contact angle measuring instrument was used to
detect the contact angle of quartz under the environment of different
reagents. In the optimal conditions, the quartz was mixed with TIPA,
TEA, TIPA/TEA, DDA and TIPA/TEA + DDA. After being fully reacted, it
was baked at a low temperature for later use. The change of contact
angle was used to analyze the influence of grinding aids and collectors
on the wettability of the quartz surface [20].
2.2.2. Flotation test
In order to avoid the influence of impurity ions on the flotation test,
the flotation materials were prepared by grinding with ceramic ball
media. After adding different types and amounts of grinding aids,
flotation materials with the quartz content of 90% -0.074 mm and 65%
-0.043 mm were obtained by controlling the grinding time. The grinding
aids and quartz were fully ground by the ceramic medium, and after
natural air drying, the flotation materials were obtained. The flotation
test was carried out by using an XFGII5–35 flotation machine equipped
with a 40 mL flotation tank at room temperature (20 ◦ C). Each time 2.0 g
of flotation materials were weighed, placed in a 40 mL flotation tank,
and distilled water was added. Subsequently, HCl and NaOH were used
to adjust the pH value of the slurry for 2 min, then the collector DDA was
added to the tank with the stirring of 3 min. After that, the pulp was
stirred for another 2 min. Scraping the foam with a scraper until all froth
products were collected. The foam products andthe products in the tank
were dried and weighed separately, and the flotation recovery was
calculated. The change of flotation recovery was used to analyze the
influence of grinding aids on the flotation behavior of quartz [16].
2.2.7. Surface tension test
The Pendant drop (PD) method in KRUSS surface tensiometer was
used to measure the surface tension of different reagents at different
concentrations. A certain amount of medicament was added to a 100 mL
beaker containing 50 mL of distilled water, and after being stirred by a
magnetic stirrer at a speed of 1800 r/min for 5 min, the surface tension
of the reagents solution under this amount was measured. Each sample
was tested 4 times and the average value was taken [21].
3. Results and discussion
3.1. Grinding efficiency test
3.1.1. Grinding experiment of a single grinding aid
Before exploring the influence of grinding aids on subsequent flota­
tion operations, the influence of grinding aids on quartz grinding effi­
ciency was worthy of priority research. Relevant studies had shown that
the finer the particle size of minerals was ground, the more significant
effect of using grinding aids [22]. In production practice, the grinding
efficiency can be expressed either as the mass of materials processed per
1 kWh of energy consumed, or as the content of new qualified grades per
1 kWh of energy consumed, so under the same grinding conditions, the
grinding efficiency is proportional to the content of qualified grade [5].
In this study, the content of − 0.043 mm was used to evaluate the index
of grinding efficiency. When the mill feed was the same, the content of
− 0.043 mm in the grinding products were directly proportional to the
grinding efficiency [23]. The molecular structure of the selected
grinding aids TIPA and TEA was shown in Fig. 3. The amount of TIPA or
TEA at 0.01%, 0.03%, 0.05%, 0.07%, and 0.09% was added to the
grinding process of quartz, the − 0.043 mm content of the resulting
grinding product was shown in Fig. 4(a). It can be seen that the content
of − 0.043 mm particle size in the grinding product first increased and
then decreased with the increase of TIPA dosage, and reached the
maximum value of 67.62% when the TIPA usage was 0.07%, which
increased by 7.62 percentage points in comparison of no grinding aid in
the process of grinding. As for the grinding aid TEA, its influence trend
on the content of − 0.043 mm particle size was consistent with TIPA, The
content of − 0.043 mm reached the maximum value of 65.61% when the
addition amount was 0.03%, which increased by 5.61 percentage points
in comparison of no grinding aid. Obviously, both TIPA and TEA can
improve the grinding efficiency of quartz, and the effect of grinding aid
TIPA was better than that of TEA.
2.2.3. FT-IR spectroscopy
A Nicolet 740 FT-IR spectrometer was used to obtain the FT-IR
spectra of quartz adsorbed with TIPA/TEA, DDA and TIPA/TEA +
DDA at room temperature (20 ◦ C). Mineral (10 g) was added to distilled
water (30 mL) to prepare a suspension, and different concentrations of
TIPA/TEA, DDA, or TIPA/TEA + DDA were added to the suspension at
pH = 6.2. After the suspension was stirred for 30 min, the quartz samples
adsorbed with TIPA/TEA, DDA and TIPA/TEA + DDA were dehydrated
and then washed with distilled water 3 times. The sample was dried at
40 ◦ C for 72 h, and 1 mg of the sample was mixed with 100 mg of
spectral pure KBr to measure FT-IR. The scanning range was from 400 to
4000 cm− 1, the resolution was 2 cm− 1, and the number of scans was 20
[17].
2.2.4. XPS measurements
The XPS spectra of TIPA/TEA, DDA and TIPA/TEA + DDA were
measured with Thermo VG ESCALAB250 spectrometer, the radioactive
source was Al-Kα, the power was 150 W, and the XPS measurement was
performed in an analysis chamber with a high vacuum of about 5.0 ×
10− 7 Pa. In each test, sample (1 g) was added to 30 mL of distilled water,
and then different reagents were added. After the solution was stirred for
0.5 h, the suspension of different samples was filtered, washed with
distilled water 3 times, and dried in vacuum at about 40 ◦ C. The test
result was calibrated using the value of C 1 s binding energy of 284.80
eV as a standard [18].
3
Y. Mao et al.
Powder Technology 406 (2022) 117570
Fig. 3. Molecular structure of grinding aid. (a) TIPA, (b) TEA.
be observed that the changes in the content of − 0.043 mm particle size
for the combined grinding aids with different mass ratios show the
similar trend within the scope of the test and investigation, namely, the
content of − 0.043 mm particle size increase first and then is reduced. As
the increase of the proportion of TIPA in the combined grinding aid, the
content of − 0.043 mm also increase. When TIPA:TEA = 2:1 and the
dosage is 0.07%, the TIPA/TEA have the best grinding effect, and the
content of − 0.043 mm increase by 9.81 percentage points than that of
no grinding aid. The grinding efficiency of combined grinding aid is
better than using TIPA or TEA individually. Relevant studies have
proved that the molecular adsorption of grinding aids can reduce the
hardness of minerals and adjust the rheological properties of the slurry,
which can be used to explain the mechanism of the grinding aids [25].
The influence of grinding aids on subsequent flotation operations and
the corrsponding mechanism are the main research focus in this article.
3.2. Flotation experiment
3.2.1. Flotation parameter optimization
Given that the low solubility in aqueous solution, DDA was selected
as the collector. It was dissolved in hydrochloric acid during the test for
use in flotation tests [26]. The dosage of DDA is fixed at 60 mg/L. Under
different pH conditions, the change in the recovery of quartz flotation is
shown in Fig. 5(a). The results indicate that the floatability of quartz in
the DDA system is significantly affected by the pH of the slurry. When
the slurry pH is 6.2, the flotation recovery of quartz reaches the
maximum value of 93.97%, thus 6.2 is as the optimal pH value and the
pH of the slurry is 6.2 to further optimize the dosage of DDA. The
relationship between the amounts of collector DDA and the recovery of
quartz is displayed in Fig. 5(b). When the dosage of collector DDA is 45
mg/L, the recovery of quartz can reach the maximum value of 93.97%,
so 45 mg/L is determined as the optimal dosage.
3.2.2. Flotation experiment with grinding aid
Based on the optimal flotation parameters, the effects of the grinding
aids TIPA and TEA on the recovery of quartz when they were added to
the grinding and directly added to the flotation process were illustrated
in Fig. 6(a). The results show that the recovery of quartz can reach the
maximum value of 96.6% after the addition of grinding aid TIPA with
the dosage of 0.03%. Compared to the condition of no grinding aid, the
recovery increases by 2.63 percentage points. Under the same condi­
tions, when the grinding aid TEA was added to the grinding process, the
recovery can reach the maximum value of 96.1% at a dosage of 0.05%.
The recovery increases by 2.13 percentage points in comparison of the
absence of grinding aid. However, when the two kinds of grinding aids
are directly added to the process of flotation, separately, (added before
the collector), the recovery of quartz has no substantial improvement.
Moreover, the recovery will be suppressed when the dosages of TIPA and
TEA are large (more than 0.09%). The main reason for the above results
Fig. 4. Influence of grinding aids on quartz grinding. (a) Single grinding aid,
(b) Combined grinding aid.
3.1.2. Grinding experiment of combined grinding aids
TIPA and TEA with similar chemical properties were both alcohol
amine organic reagents, and there was no chemical reaction between the
two reagents at room temperature [24]. In order to further improve the
grinding efficiency of quartz and the adaptability of grinding aids, TIPA
and TEA were used in combination under optimal grinding conditions.
The effect of TIPA and TEA on the grinding efficiency of quartz at three
mass ratios (1:1, 1:2 and 2:1) and five dosages (0.01%, 0.03%, 0.05%,
0.07% and 0.09%) were studied, the result was shown in Fig. 4(b). It can
4
Y. Mao et al.
Powder Technology 406 (2022) 117570
Fig. 6. Influence of grinding aids on quartz flotation. (a) Single grinding aid,
(b) Combined grinding aid.
Fig. 5. Flotation parameter optimization. (a) pH, (b) Collector dosage.
combined grinding aid mass ratio 2:1, dosage 0.05%. The mechanism of
the influence of grinding aids on the flotation behavior of quartz in the
DDA flotation system is investigated by using a variety of detection
methods and MS computer simulation technology.
can be attributed to the addition of grinding aid in the process of
grinding, which is beneficial to extend the time for the reagent to
interact with the quartz, and there is a mechanochemical effect in the
media grinding, which can increase the adsorption on the quartz surface
and thus result in the enhancement of recovery.
Since the chemical composition of the combined reagent is consistent
with the two single reagents, this article will not discuss the influence of
the location of the combined reagent on quartz flotation. From Fig. 6(b),
it can be seen that the TIPA/TEA combined grinding aid is added to the
process of grinding before flotation, in three mass ratios (TIPA:TEA
=1:1, 1:2 and 2:1), with the increase in the amount of combined
grinding aids, the flotation recovery exhibits the similar law, that is,
increasing firstly and then decreased. Under the same dosage of com­
bined grinding aid, the recovery of quartz increased with the increase of
the TIPA ratio in the combined grinding aid. When the mass ratio of
TIPA to TEA is 2:1 and the dosage is 0.05%, the largest flotation recovery
rate of 98.4% is obtained, increasing by 4.43 percentage points in
comparison of no grinding aid. After TIPA and TEA are mixed, the
number of effective groups on the surface of quartz will increase, which
results in the improvement of recovery by the combined action of the
two reagents. It should be pointed out that the synergy between the
grinding aid and the collector plays a vital role in the increase of re­
covery. Since the TIPA/TEA combined grinding aid has better effect on
quartz grinding efficiency and flotation recovery than a single grinding
aid and the groups of the combined grinding aid are the same as that of a
single grinding aid, the experiment is optimized under the flotation
conditions as follows: DDA dosage 45 mg/L, pH = 6.2, TIPA/TEA
3.3. FT-IR spectroscopy analysis
The functional groups of the combined grinding aid TIPA/PEA and
the collector DDA were measured by FT-IR after fully interacting with
quartz under optimal conditions, the results are shown in Fig. 7. The
Fig. 7. FT-IR spectra of quartz in different systems.
5
Y. Mao et al.
Powder Technology 406 (2022) 117570
absorption peak of quartz at 3142.18 cm− 1 is the characteristic ab­
sorption peak of -OH, and the absorption peak at 1404.24 cm− 1 is the
stretching vibration peak of quartz adsorbing -OH in water [27]. Besides
the absorption peak located at 775.12 cm− 1 can be ascribed to the
stretching vibration of Si-O-Si bond, while the absorption peak posi­
tioned at 695.04 cm− 1 corresponds to the bending vibration Si–O bond
[28]. After the reaction of quartz with the TIPA/PEA, the absorption
peak situated at 695.04 cm− 1 shifts to 692.14 cm− 1 and the absorption
peak at 775.12 cm− 1 shifts to 771.63 cm− 1. No new functional groups
are generated, demonstrating that the interaction between the combined
grinding aid and the surface of quartz belongs to physical adsorption.
Furthermore, the absorption peak at 1404.24 cm− 1 shifts to 1400.19
cm− 1, and the absorption peak at 3142.18 cm− 1 shifts to 3140.25 cm− 1,
indicating that TIPA/TEA has hydrogen bond adsorption on quartz [29].
After the reaction of quartz with DDA, the absorption peak at 695.04
cm− 1 shifts to 690.90 cm− 1, and the absorption peak at 775.12 cm− 1
shifts to 762.07 cm− 1, which reveals that DDA has physical attachment
to the surface of quartz. Additionally, the shifting of absorption peak
from 1404.24 cm− 1 shifts to 1390.73 cm− 1 and 3142.18 cm− 1 shifts to
3133.21 cm− 1 are derived from the hydrogen bond adsorption of DDA
on the surface of quartz. Based on the above analysis, no new absorption
peak produces on the surface of quartz and the corresponding peak in­
tensity is weakened, signifying that neither the grinding aid nor the
collector has chemical adsorption on the surface of quartz [30]. After the
combined grinding aid is introduced into the DDA flotation system, the
peak offsets increas compared to the Quartz + DDA flotation system,
which indicats that the combined grinding aid has a certain promotion
effect on the adsorption of DAA on the surface of quartz.
3.4. XPS analysis
Fig. 8. XPS O 1 s scans of quartz. (a) Quartz + DDA, (b) Quartz + TIPA/TEA
+ DDA.
In order to further explore the adsorption mechanism of the com­
bined grinding aid and collector on the surface of quartz, XPS analysis
was performed on the sample after the action of the reagent, and the
results are shown in Table 2. After the addition of TIPA/TEA to the
grinding, the binding energy of Si on the surface of quartz did not change
significantly compared to the combination of quartz and DDA, and the
binding energy of O increases by 0.09 eV. The results suggest that TIPA/
PEA and DDA mainly interacted with O on the surface of quartz. Peak
fitting was performed on O 1 s on the surface of quartz, and the results
are shown in Fig. 8. From Fig. 8(a), it can be seen that in the O 1 s peak
fitting between DDA and Quartz, the binding energies of 532.60 eV and
532.11 eV correspond to the peak positions of -OH and Si–O, respec­
tively [31], where -OH is mainly derived from quartz during the
grinding process. The possible reason can be attributed to part of the
Si–O on the surface breaks electrostatically reacted with the ionized H+
in the water to generate -OH or the fracture surface is -O-Si2+, which
electrostatically reacted with the ionized OH− in the water to form -OH
[32]. Fig. 8(b) shows that after adding grinding aids in grinding, both
TIPA/TEA and DDA interacted with the surface of quartz. Besides, the
position of -OH peak shifts from 532.60 eV to 532.71 eV with an increase
of 0.11 eV, while the position of Si-O peak shifts from 532.11 eV to
532.20 eV with an increase of 0.09 eV, the results further prove that the
addition of TIPA/TEA has a certain promotion effect on the adsorption
of DDA on the surface of quartz instead of inhibition.
3.5. Quantum chemistry calculation
The CASTEP module in Materials Studio was used to optimize the
structure of the quartz unit cell, the energy cutoff was set as 460 eV, the
functional was set as GGA-PBESOL, and the self-consistent iteration
accuracy of the calculation was set as 1 × 10− 6 eV/atom, k-point was 3
× 3 × 4 [33]. Under the above conditions, the quartz cell parameters
were simulated. The comparative results of the optimized quartz cell
parameters and empirical values are shown in Table 3. It is obvious that
the error between the optimized quartz cell parameters and the empir­
ical value is small, demonstrating that the optimized structure is correct
and conforms to the actual situation. Fig. 9(a) is the optimized quartz
cell. The quartz cell was cut along the (101) plane with the thickness of
1.5 layers, and the top atoms were adjusted to make the ratio of the
number of exposed Si atoms and O atoms equal to 1:1. Since the CASTEP
module can only optimize the three-dimensional unit cell, while the cut
out (101) crystal plane is a two-dimensional planar structure [34], it is
necessary to establish a vacuum layer and optimize the quartz (101)
plane, where the thickness of the vacuum layer was set as 15 Å (Fig. 9
(b)). The unit cell is expanded into a 2 × 2 × 1 supercell (Fig. 9(c)), and
the bottom atoms are fixed before relaxing the first layer atoms. As
shown in Fig. 10(a), there is no obvious difference between the
Table 3
The optimized quartz cell parameters are compared to the empirical values.
Table 2
Binding energy of quartz surface in different reagents.
Sample
Si/eV
C/eV
O/eV
Quartz + TIPA/TEA
Quartz + DDA
Quartz + TIPA/TEA +DDA
103.06
103.07
103.07
284.8
284.8
284.8
532.35
532.39
532.48
6
Parameter
Experience
Optimized
Error/%
a/Å
b/Å
c/Å
Si-O bond length /Å
Si-O-Si bond angle /◦
4.914
4.914
5.405
1.608–1.610
143.700
5.030
5.030
5.509
1.615–1.618
149.471
2.360
2.360
1.920
0.440–0.500
4.020
Y. Mao et al.
Powder Technology 406 (2022) 117570
Fig. 9. Quartz cells. (a) Optimized cells； (b) Cell after cutting the surface； (c) Expanded cell.
energy band of quartz is divided into three parts in the range of − 20 eV
to 15 eV, the valence band − 20 to − 15 eV and − 15 eV to − 2.5 eV is
mainly contributed by O, while the valence band ranging from 5 eV to
15 eV is mainly contributed by Si, the valence band at the Fermi level is
mainly contributed by O, only a small amount is Si [35]. Therefore,
reagent molecules will mainly interact with O on the (101) surface of
quartz, which is consistent with the analysis of XPS characterization .
The adsorption energy of the reagent on the surface of quartz was
calculated (by Eq. (2)) under the conditions of a universal force field and
an accuracy of ultra-fine [36]. The smaller the adsorption energy be­
tween the reagent and the mineral, the stronger the adsorption effect of
the reagent on the surface of mineral [37]. According to the simulation
calculation results, the adsorption energy of each adsorbate (grinding
aids, collector) on the surface of quartz is shown in Table 4. It can be
obtained that in the wet grinding environment, the adsorption energy of
H2O on the surface of quartz is − 0.05 eV, indicating that H2O can be
adsorbed on the surface of quartz, but the adsorption effect is weak. The
adsorption effect of combined grinding aids TIPA/TEA on the surface of
quartz is stronger than that of single TIPA or TEA. Compared with single
grinding aid, the combined grinding aids have more polar groups, so the
adsorption effect is enhanced. The adsorption energy after the interac­
tion of DDA with quartz is − 72.77 eV, which is relatively large in ab­
solute value, suggesting that it is easy to adsorb on the surface of quartz.
Compared to the system of DDA, the absolute value of the DDA + TIPA/
TEA increases, showing that the grinding aid has no competitive
adsorption with the collector DDA on the surface of quartz, and the
adsorption of the collector DDA is promoted.
)
(
ΔEads = Ecomplex − Ereagent + Emineral
(2)
Where ΔEads is the adsorption energy of the agent on the surface of
mineral, Ecomplex is the energy after the agent interacts with the mineral,
Ereagent is the energy of the reagent, Emineral is the energy of the mineral.
Table 4
The adsorption energy of reagents on the (101) surface of quartz.
Fig. 10. X-ray diffraction patterns and density of state of quartz. (a) XRD,
(b) DOS.
simulated quartz XRD spectrum of the experiment and the actual XRD,
suggesting that the crystal structure of the optimized quartz is consistent
with the actual one. After optimization, the density of states of quartz
was calculated by the CASTEP in Fig. 10(b). It can be observed that the
7
Reagents
Ecomplex/eV
Ereagent/eV
Emineral/eV
ΔEads/eV
H2O
TIPA
TEA
TIPA/TEA
DDA
TIPA/TEA + DDA
− 34,909.56
− 36,768.40
− 36,836.17
− 36,965.03
− 37,652.78
− 37,701.29
− 466.91
− 2316.37
− 2387.21
− 2507.89
− 3137.41
− 3178.84
− 34,442.60
− 34,442.60
− 34,442.60
− 34,442.60
− 34,442.60
− 34,442.60
− 0.05
− 9.43
− 6.36
− 14.54
− 72.77
− 79.85
Y. Mao et al.
Powder Technology 406 (2022) 117570
3.6. Solution chemical analysis
demonstrates that the grinding aids effectively adsorb on the surface of
quartz. The order of the contact angle is TIPA/TEA > TIPA > TEA, which
is mainly due to the larger number of non-polar carbon chains in the
TIPA molecule was more than that of TEA under the same dosage.
Similarly, the number of non-polar carbon chains in the TIPA/TEA is
more than that of a single grinding aid. The hydrophobicity of quartz
increases by the non-polar carbon chain. The contact angle of quartz and
DDA is 78.7◦ , meaning excellent floatability. After the introduction of
TIPA/TEA, the contact angle is 84.2◦ , indicating that the TIPA/TEA can
increase the hydrophobicity of quartz under the DDA system and further
improve the floatability of quartz, which is consistent with the conclu­
sion of the quartz flotation experiment under the action of the grinding
aid.
Obviously, DDA in the solution exists in different forms due to the
change of pH . Under the optimal flotation environment of pH = 6.2,
DDA mainly exists in the form of cationic groups such as RNH+
3 or
2+
(RNH+
3 )2 [38]. During the process of wet grinding, the fracture surface
of the quartz mineral particles is -Si-O− , which electrostatically reacted
with the ionized H+ in the water to generate hydroxyl groups, or the
fracture surface is -O-Si2+, which electrostatically reacted with the
ionized OH− in the water to form hydroxyl groups. The -OH was further
ionized to make the surface of the quartz to produce Si-O- [32]. Mean­
while, the cationic group of DDA was adsorbed on the surface of quartz
with negatively charged by electrostatic force. As we all know, both
TIPA and TEA are easily miscible with water, there are lone electrons in
the N atom, which adsorbed H+ in the solution and appeared weakly
alkaline. However, in the flotation environment of weakly acidic with
pH was 6.2, TIPA/TEA was mainly existed in the form of moleculars
[39]. Since the electronegativity of O in its molecule is stronger than that
of N, -OH is the polar group of TIPA/TEA [40]. Based on the FT-IR
spectroscopy and XPS analysis as well as the reported simulation re­
sults [41], it can be found that the adsorption energy of TIPA and TEA on
the surface of mineral particles is 20–50 Kcal/mol, which belongs to the
adsorption range of hydrogen bonds. So, it demonstrates that the polar
group -OH in the TIPA/TEA forms a hydrogen bond with O on the sur­
face of quartz. From the calculation results of the adsorption energy, we
can know that the strength of the hydrogen bond adsorption is weaker
than that of the electrostatic adsorption of DDA, while the adsorption of
DDA is stronger than the grinding aid, Besides, according to the con­
servation of charge, it can be known that the hydrogen bond adsorption
will not offset the negative potential on the surface of quartz, that is to
say, the quartz surface after the adsorption of the TIPA/TEA is still
charged with a negative potential, so TIPA/PEA will not compete with
DDA for adsorption on its surface.
3.8. Surface tension detection
The surface tension of the flotation solution has an important effect
on the flotation behavior, it can cause changes in properties such as the
dissolution and foaming of the flotation reagent [44]. Therefore, under
the respective optimal dosages, the effect of TIPA/TEA on the surface
tension of the DDA solution was studied. The solution temperature
during the test was about 26 ◦ C, and the surface tension of deionized
water was measured as 71.96 mN/m, the test results are shown in
Fig. 12. It can be found that as the concentration of the solution in­
creases, the surface tension of the solutions under the two medicament
environments shows an overall downward trend, and after the addition
of TIPA/TEA, the surface tension of DDA decreases significantly. When
the concentration of DDA is 8.0 × 10− 3 mol/L and no any grinding aids
in the solution, the surface tension declines to the lowest value and re­
mains almost unchanged. It is no longer affected by the concentration of
the reagent, and gradually changing from a downward trend to level off.
The concentration at the inflection point is the critical micelle concen­
tration of the solution at this temperature (CMC) [45], and the CMC
value of DDA is 8.0 × 10− 3 mol/L, which is in good agreement with the
conclusions of the relevant literature [46]. After the addition of TIPA/
TEA, the CMC value of DDA is 4.0 × 10− 3 mol/L, which shows that the
introduction of grinding aids can reduce the CMC value of DDA solution,
moreover, it can improve the water solubility and dispersibility of DDA,
and thus increase the utilization rate of DDA. Therefore, the recovery of
quartz can be improved by TIPA/TEA.
3.7. Contact angle analysis
In practice, the contact angle was usually used to measure the
wettability of a solid surface [42]. The changes in the contact angle of
different reagents on the surface of quartz under optimal conditions
were tested, and the results are shown in Fig. 11. Without adding re­
agent, the contact angle of quartz is small, indicating that the surface of
quartz has strong hydrophilicity, which means that it has poor natural
floatability [43]. After the reaction of quartz with TIPA, TEA and their
combined grinding aids, the contact angle increases significantly, which
4. Conclusions
This paper focused on the study of the effect of TIPA/TEA combined
grinding aids in the grinding and flotation behavior of quartz. The
Fig. 11. The contact angle of quartz under the action of different reagents.
Fig. 12. Results of surface tension tests.
8
Powder Technology 406 (2022) 117570
Y. Mao et al.
following conclusions can be draw from the experiment.
[6] F. Cheng, Y. Feng, Q.Q. Su, D.D. Wei, B. Wang, Y.W. Huang, Practical strategy to
produce ultrafine ceramic glaze: introducing a polycarboxylate grinding aid to the
grinding process, Adv. Powder Technol. 30 (8) (2019) 1655–1663.
[7] P. Prziwara, A. Kwade, Grinding aids for dry fine grinding processes-part I:
mechanism of action and lab-scale grinding, Powder Technol. 375 (2020) 146–160.
[8] N. Singh, R.S. Chatterjee, D. Kumar, D.C. Panigrahi, Spatio-temporal variation and
propagation direction of coal fire in Jharia coalfield, India by satellite-based multitemporal night-time land surface temperature imaging, Int. J. Min. Sci. Technol. 31
(5) (2021) 765–778.
[9] A.F. Rosa, J. Rubio, On the role of nanobubbles in particle–bubble adhesion for the
flotation of quartz and apatitic minerals, Miner. Eng. 127 (2018) 178–184.
[10] L.Y. Ren, H. Qiu, Y.M. Zang, A.V. Nguyen, M. Zang, P.G. Wei, et al., Effects of alkyl
ether amine and calcium ions on fine quartz flotation and its guidance for
upgrading vanadium from stone coal, Powder Technol. 338 (2018) 180–189.
[11] Y.S. Wang, W.G. Zhou, Y.J. Li, L. Liang, G.Y. Xie, L. PengY, The role of
polyvinylpyrrolidone in the selective separation of coal from quartz and kaolinite
minerals, Colloid Surf. A 626 (2021).
[12] Z.Y. Cheng, Y.M. Zhu, Y.J. Li, S. Butt, Experimental and MD simulation of 3dodecyloxypropanamine and 3-tetradecyloxypropylamine adsorbed onto quartz (1
0 1) surface, Int. J. Min. Sci. Technol. 31 (2) (2021) 153–162.
[13] P. Bulejko, N. Sulekova, J. Vlasak, R. Tuunila, T. Kinnarinen, T. Sverak, et al.,
Ultrafine wet grinding of corundum in the presence of triethanolamine, Powder
Technol. 395 (2022) 556–561.
[14] N.A. Toprak, O. Altun, A.H. Benzer, The effects of grinding aids on modelling of air
classification of cement, Constr. Build. Mater. 160 (2018) 564–573.
[15] J. Yang, S.H. Li, X.S. ChEng, Q. Li, Disturbance rejection of ball mill grinding
circuits using DOB and MPC, Powder Technol. 198 (2010) 219–228.
[16] J.Z. Wang, Y. Mao, Y.Z. Cheng, Y.C. Xiao, Y.X. Zhang, J.Z. Bai, Effect of Pb(II) on
the flotation behavior of scheelite using sodium oleate as collector, Miner. Eng. 136
(2019) 161–167.
[17] C. Han, H. Zhang, R. Tan, Y.B. Shen, D.Z. Wei, W.G. Liu, Effects of monohydric
alcohols of varying chain lengths and isomeric structures on magnesite and
dolomite flotation by dodecylamine, Powder Technol. 374 (2020) 233–240.
[18] Y.B. Shen, S.K. Zhao, J.W. Ma, X.X. Chen, W. Wang, D.Z. Wei, et al., Highly
sensitive and selective room temperature alcohol gas sensors based on TeO2
nanowires, J. Alloys Compd. 664 (2016) 229–234.
[19] W.G. Liu, H. Duan, D.Z. Wei, B.Y. Cui, X.Y. Wang, Stability of diethyl
dithiocarbamate chelates with Cu(II), Zn(II) and Mn(II), J. Mol. Struct. 1184
(2019) 375–381.
[20] X.B. Lu, J.P. Liu, X.W. Xu, Contact angle measurements of pure refrigerants, Int. J.
Heat Mass Transf. 102 (2016) 877–883.
[21] F. Celestini, E. Bormashenko, Propulsion of liquid marbles: a tool to measure their
effective surface tension and viscosity, J. Colloid Interface Sci. 532 (2018) 32–36.
[22] N.A. Toprak, A.H. Benzer, Effects of grinding aids on model parameters of a cement
ball mill and an air classifier, Powder Technol. 344 (2019) 706–718.
[23] X.Q. Zhai, M. Qu, X. Yu, Y. Yang, R.Z. Wang, A review for the applications and
integrated approaches of ground-coupled heat pump systems, Renew. Sust. Energ.
Rev. 15 (6) (2011) 3133–3140.
[24] H. Huang, X.D. Shen, Interaction effect of triisopropanolamine and glucose on the
hydration of Portland cement, Constr. Build. Mater. 65 (2014) 360–366.
[25] X. Zhang, H.R. Hu, Preparation and analysis of a polyacrylate grinding aid for
grinding calcium carbonate (GCC) in an ultrafine wet grinding process, Powder
Technol. 254 (2014) 470–479.
[26] W.B. Liu, W.G. Liu, B.Y. Wang, H. Duan, X.Y. Peng, X.D. Chen, et al., Novel
hydroxy polyamine surfactant N-(2-hydroxyethyl)-N-dodecyl-ethanediamine: its
synthesis and flotation performance study to quartz, Miner. Eng. 142 (2019),
105894.
[27] R.R. Dagastine, D.C. Prieve, L.R. White, Calculations of van der Waals forces in 2dimensionally anisotropic materials and its application to carbon black, J. Colloid
Interface Sci. 249 (1) (2002) 78–83.
[28] L. Wang, G.D. Wang, P. Ge, W. Sun, H.H. Tang, W.J.H. Hu, Activation mechanisms
of quartz flotation with calcium ions and cationic/anionic mixed collectors under
alkalescent conditions, Colloid Surf. A 632 (2022), 127771.
[29] Y.F. Xie, Y.Y. Huang, W.Z. Wang, G.Q. Liu, R. Zhao, Dynamic interaction between
melamine and cyanuric acid in artificial urine investigated by quartz crystal
microbalance, Analyst 136 (12) (2011) 2482–2488.
[30] T. Sato, K. Kunimatsu, K. Okaya, H. Yano, M. Watanabe, H. Uchida, In situ ATRFTIR analysis of the CO-tolerance mechanism on Pt2Ru3/C catalysts prepared by
the nanocapsule method, Energy Environ. Sci. 4 (2) (2011) 433–438.
[31] S. Aggoun, M. Cheikh-Zouaoui, N. Chikh, R. Duval, Effect of some admixtures on
the setting time and strength evolution of cement pastes at early ages, Constr.
Build. Mater. 22 (2) (2008) 106–110.
[32] L. Wang, W. Sun, Y.H. Hu, L.H. Xu, Adsorption mechanism of mixed anionic/
cationic collectors in muscovite - quartz flotation system, Miner. Eng. 64 (2014)
44–50.
[33] T. Xu, Y.P. Wu, S. Bhattacharya, Gasification kinetic modelling of Victorian brown
coal chars and validity for entrained flow gasification in CO2, Int. J. Min. Sci.
Technol. 31 (3) (2021) 473–481.
[34] C.L. Peng, G.S. Wang, C.L. Zhang, L. Qin, X. Zhu, S.H. Luo, Molecular dynamics
simulation of NH+
4 -smectite interlayer hydration: influence of layer charge density
and location, J. Mol. Liq. 336 (2021), 116232.
[35] L.P. Luo, H.Q. Wu, L.H. Xu, J.P. Meng, J.H. Lu, H. Zhou, et al., An in situ ATR-FTIR
study of mixed collectors BHA/DDA adsorption in ilmenite-titanaugite flotation
system, Int. J. Min. Sci. Technol. 31 (4) (2021) 689–697.
(1) The suitable dosage of TIPA/PEA combined grinding aid in the
process of quartz grinding can not only significantly improve the
grinding efficiency of quartz, but also increase the flotation re­
covery of quartz.
(2) According to the results of FT-IR spectroscopy and XPS analysis,
TIPA/PEA and DDA have physical and hydrogen bond adsorption
on the surface of quartz, and TIPA/PEA combined grinding aid
can promote the adsorption of collectors on the surface of quartz.
Based on quantum chemistry calculation and chemical analysis of
the solution, it shows that the reagent mainly interacted with the
O on the (101) surface of quartz. After the TIPA/PEA is intro­
duced into the quartz flotation system, the adsorption energy of
DDA on the quartz surface increases. On the (101) surface of
quartz, the collector DDA is mainly adsorbed on the negatively
charged by electrostatic force, and the polar group -OH in the
TIPA/PEA forms a hydrogen bond with O on it. The TIPA/PEA
and collector play a synergistic effect on the surface of quartz
instead of competitive adsorption.
(3) The test results of contact angle and solution surface tension show
that TIPA/PEA can increase the contact angle of quartz under
DDA system and improve the hydrophobicity of quartz. Besides,
TIPA/PEA can reduce the surface tension and CMC value of DDA
solution and increase the water solubility and dispersibility of the
DDA. It can also promote the adsorption of DDA on the surface of
quartz, and thus can improve the recovery of quartz flotation.
CRediT authorship contribution statement
Yong Mao: Investigation, Conceptualization, Methodology, Data
curation, Funding acquisition, Writing – original draft. Zehong Wang:
Supervision, Conceptualization, Project administration. Wengang Liu:
Visualization, Investigation. Pengcheng Tian: Software, Validation.
Declaration of Competing Interest
No conflict of interest exits in the submission of this manuscript, and
manuscript is approved by all authors for publication. I would like to
declare on behalf of my co-authors that the work described was original
research that has not been published previously, and not under
consideration for publication elsewhere, in whole or in part. All the
authors listed have approved the manuscript that is enclosed.
Acknowledgements
This work was supported by the National Natural Science Foundation
of China (51874073) and the Fundamental Research Funds for the
Central Universities (N2101047). The authors would like to thank the
testing service from Analytical and Testing Center, Northeastern Uni­
versity (Shenyang, China).
References
[1] P. Prziwara, S. Breitung-Faes, A. Kwade, Comparative study of the grinding aid
effects for dry fine grinding of different materials, Miner. Eng. 144 (2019), 106030.
[2] Y.H. Tan, L. Sha, J. Qu, J.Q. Jiang, J. Ren, C.J. Wu, et al., Oleic acid as grinding aid
and surface antioxidant for ultrafine zirconium hydride particle preparation, Appl.
Surf. Sci. 535 (2021), 147688.
[3] M. Katsioti, P.E. Tsakiridis, P. Giannatos, Z. Tsibouki, J. Marinos, Characterization
of various cement grinding aids and their impact on grindability and cement
performance, Constr. Build. Mater. 23 (5) (2009) 1954–1959.
[4] T.L. Zhang, J.M. Gao, J.C. Hu, Preparation of polymer-based cement grinding aid
and their performance on grindability, Constr. Build. Mater. 75 (2015) 163–168.
[5] H.X. Li, J.F. Zhao, Y.Y. Huang, Z.W. Jiang, X.J. Yang, Z.H. Yang, et al.,
Investigation on the potential of waste cooking oil as a grinding aid in Portland
cement, J. Environ. Manag. 184 (2016) 545–551.
9
Y. Mao et al.
Powder Technology 406 (2022) 117570
[36] S. Nasirimoghaddam, A. Mohebbi, M. Karimi, M.R. Yarahmadi, Assessment of pHresponsive nanoparticles performance on laboratory column flotation cell applying
a real ore feed, Int. J. Min. Sci. Technol. 30 (2) (2020) 197–205.
[37] H.M. Yu, H.J. Wang, C.Y. Sun, Comparative studies on phosphate ore flotation
collectors prepared by hogwash oil from different regions, Int. J. Min. Sci. Technol.
28 (3) (2018) 453–459.
[38] L. Shen, H.F. Wang, B.L. Guo, H. Wang, The application of fatty acids emulsions in
thermal coal reverse flotation, Int. J. Coal Prep. Util. 36 (3) (2016) 163–173.
[39] Z.P. Sun, Y. Liu, A grindability model for grinding aids and their impact on cement
properties, Adv. Cem. Res. 28 (7) (2016) 475–484.
[40] M. Lenninger, N. Aguilo-Aguayo, T. Bechtold, Quantification of triethanolamine
through measurement of catalytic current in alkaline iron-D-gluconate solution,
J. Electroanal. Chem. 830 (2018) 50–55.
[41] H. Huang, X.D. Shen, Influence of low-dose chemicals on the early strength of
Portland cement: statistical and calorimetric evidence, Adv. Cem. Res. 29 (4)
(2017) 155–165.
[42] P.F. Lv, Y. Liu, Z. Wang, S.Y. Liu, L.L. Jiang, J.L. Chen, Y.C. Song, In situ local
contact angle measurement in a CO2-brine-sand system using microfocused X-ray
CT, Langmuir 33 (14) (2017) 3358–3366.
[43] S. Cicek, I.B. Tulu, M.V. Dyke, T. Klemetti, J. Wickline, Application of the coal
mine floor rating (CMFR) to assess the floor stability in a central Appalachian coal
mine, Int. J. Min. Sci. Technol. 31 (1) (2021) 83–89.
[44] P. Zhou, J. Hou, Y.G. Yan, J.Q. Wang, W. Chen, Effect of aggregation and
adsorption behavior on the flow resistance of surfactant fluid on smooth and rough
surfaces: a many-body dissipative particle dynamics study, Langmuir 35 (24)
(2019) 8110–8120.
[45] W.B. Liu, W.G. Liu, S.J. Dai, T. Yang, Z. Li, P. Fang, Enhancing the purity of
magnesite ore powder using an ethanolamine-based collector: insights from
experiment and theory, J. Mol. Liq. 268 (2018) 215–222.
[46] M.B.M. Monte, J.F. Oliveira, Flotation of sylvite with dodecylamine and the effect
of added long chain alcohols, Miner. Eng. 17 (3) (2004) 425–430.
10