
==== Front
ACS Omega
ACS Omega
ao
acsodf
ACS Omega
2470-1343
American Chemical Society

10.1021/acsomega.4c05225
Article
Effect of Surfactants on Eliminating Stable Ultrafine Chalcopyrite Froth
https://orcid.org/0009-0004-3610-9566
Xu Shaomei *
Lu Xiangyu
Dai Zhifei
https://orcid.org/0000-0001-5784-0949
Li Shuai
Xiao Gang
Huai Yangyang *
Jiangxi Copper Technology Institute Co., Ltd., Nanchang 330096, China
* Email: 893450636@qq.com.
* Email: huai@jxcc.com.
26 08 2024
10 09 2024
9 36 3808838095
03 06 2024
14 08 2024
11 07 2024
© 2024 The Authors. Published by American Chemical Society
2024
The Authors
https://creativecommons.org/licenses/by-nc-nd/4.0/ Permits non-commercial access and re-use, provided that author attribution and integrity are maintained; but does not permit creation of adaptations or other derivative works (https://creativecommons.org/licenses/by-nc-nd/4.0/).

Chalcopyrite is a primary source of copper in nature. However, with the increasing need to process low-grade and complex chalcopyrite ores, overly stable froth is becoming more and more common and poses operational and safety challenges. No reliable strategy has been developed to address the issue. As a new initiative, this study investigated three different structured surfactants, sodium dodecyl sulfate (SDS), sodium dodecylbenzenesulfonate (SDBS), and pentadecafluorooctanoic acid (PFOA), which vary in hydrophobic group, aiming to modify the surfaces of ultrafine chalcopyrite particles and adjust the interfacial tension at the gas–liquid interface to eliminate stable ultrafine chalcopyrite froth. The fundamental hypothesis was that an ideal surfactant structure could adjust the particle surface wettability and interfacial tension to eliminate overly stable froth. Based on contact angle measurements and interfacial tension measurements using a Theta Flow tensiometer by the pendant drop method and the sessile drop method, it was demonstrated that the contact angle played a dominant role in defoaming, while the reduction of gas–liquid interfacial tension had an adverse effect. Additionally, defoaming tests indicated that SDBS had lower defoaming effectiveness than SDS at low surfactant concentrations due to the steric hindrance in its structure, whereas the addition of SDBS could achieve a froth reduction efficiency as high as 93.75% at higher surfactant concentrations due to its stronger hydrophobicity and adsorption capacity to chalcopyrite particles, which could reduce the contact angle from 70 to 37.62°. However, PFOA exhibited lower defoaming effectiveness than both SDS and SDBS due to its lipophobic fluorocarbon tail of PFOA and weaker adsorption capacity to chalcopyrite particles, making it unsuitable for eliminating stable ultrafine chalcopyrite froth.

Jiangxi Science and Technology Major Program NA 20232ACE01010 document-id-old-9ao4c05225
document-id-new-14ao4c05225
ccc-price
==== Body
pmc1 Introduction

Copper is one of the most essential nonferrous metals required across various modern industries. Due to its excellent thermal and electrical conductivity and high ductility, it is widely used in industrial, agricultural, construction, military, and aerospace sectors. Among industrially valuable copper ores worldwide, over 80% are sulfide copper ores, with chalcopyrite being the most common, constituting approximately 66.7% of the total copper minerals. Its formula is CuFeS2, with a copper content of 34.78%.1,2 Froth flotation is currently one of the most widely used methods for chalcopyrite beneficiation. Its principle is to exploit the hydrophobicity of mineral surfaces to separate and extract chalcopyrite from gangue minerals through froth.3 Typically, coarse-grained minerals lead to unstable froth, while fine-grained minerals cause overly stable froth.4−6 Nowadays, with the increasing need to process low-grade and complex chalcopyrite ores, ultrafine grinding of chalcopyrite ores has become more common to ensure the separation of chalcopyrite, which leads to overly stable froth.7−9 However, the overly stable froth poses various challenges for pumping, defoaming, and dewatering operations. For example, accumulation of overly stable froth on thickener leads to the entry of froth into the circulating water, causing the loss of valuable metal, contamination of the recirculating water, and lower concentration efficiency.10−12 In the dewatering process, overly stable froth results in inefficient pressure and vacuum filtration, leading to a high moisture in filter cakes. Moreover, overly stable froth can affect the pipeline pumping system, reducing pumping efficiency, exacerbating cavitation effects, and decreasing the lifespan of pumps.11

Currently, defoaming methods mainly fall into two categories: physical defoaming and chemical defoaming. Physical defoaming alters the physical state of froth through methods such as standing, depressurization, heating, mechanical stirring, water spraying, and ultrasonication,13−15 which enhances the permeation rate of air at both ends of the liquid film and facilitate the drainage of the froth, resulting in a decrease in the quantity of froth. The advantages of these methods lie in environmentally friendly and high reusability.14 However, they are limited by some drawbacks, including high energy consumption and low defoaming effectiveness. Chemical defoaming involves adding various defoamers, such as polyether-based defoamers, silicone-based defoamers, and oil-based defoamers.16−18 The mechanism of all of these defoamers involves disrupting and inhibiting the formation of the bubble bimolecular film. When defoamers enter the biomolecularly oriented film of the foam, the adsorbed defoamer molecules replace the collector and foamer molecules, forming a weaker film. Additionally, during the spreading process, defoamers remove some of the solution from the adjacent surface layer, thinning the foam liquid film, reducing its stability, and making it easier to break.17−19 Joshi et al.20 investigated the effect of alkoxylated alcohol block copolymer (BCP, RO-(PO)x-(EO)y, where R represents an alkyl chain and EO and PO correspond to ethylene and propylene oxides, respectively) drops as defoamers. The results showed a significant ability of the BCP to destabilize foam with 20–30 wt % BCP in solution. Perez et al.21 found that silicone oil (polydimethylsiloxane) as a defoamer with molar masses ranging from 8 to 30 kg mol–1 exhibited the highest froth reduction efficiency of 75% for defoamers dosed above 15 ppm. These methods have the advantages of high defoaming effectiveness and ease of use. However, these methods suffer from several limitations such as high cost, poor heat resistance, and insolubility in water, which significantly affect the defoaming performance.19,22 Therefore, it is still important to develop efficient and suitable methods for defoaming in the dewatering processes.

It has been proved that froth stability highly depends on various factors, such as particle size and contact angle, air–liquid interfacial tension, reagent type, and dosage.6,23−26 Liang et al.27 investigated the effect of mineral particles of different sizes and hydrophobicity on froth stability by measuring the maximum froth height and froth half-life time. The results showed that finer particles of higher hydrophobicity contributed to higher levels of froth stability. The degree of hydrophobicity on the particle surfaces is a crucial parameter influencing the froth stability. Studies have shown that stable froth cannot exist in systems with either strongly hydrophilic or strongly hydrophobic particles.28,29 Johansson and Pugh30 discovered that as the hydrophobicity of the particles increased, the froth stability enhanced to reach a peak and then began to decline. It has been reported that the introduction of hydrophobic particles had no effect on the froth stability. Qiu et al.31 investigated the mechanisms of the effects of various structured collectors on the interfacial water at the gas–liquid interface; with the decrease in interfacial tension, the froth became more stable through hydrogen bonding, van der Waals forces, and steric hindrance effects between molecules, leading to water molecule rearrangement in the interface region. Pichot et al.32 investigated the effects of surfactant type and concentration on interfacial tension in the presence of silica particles and found that both particles and surfactants were adsorbed at the interface and strongly affected interfacial tension.

Surfactants typically have a lower cost and higher heat resistance compared to common defoamers and are soluble in water. However, the effectiveness of the same surfactant varies with different types of foamers and collectors, making it crucial to find the appropriate surfactant. They consist of two parts in molecular structure: one end is a hydrophilic polar group, and the other end is a hydrophobic nonpolar group. Surfactants can adsorb on the surface of the liquid film, reducing the surface energy. When surfactants absorb at the gas–liquid interface, they form a monolayer with hydrophilic groups in contact with water and hydrophobic groups exposed to air, affecting the gas–liquid interfacial tension.33,34 Furthermore, surfactants can modify the particle surfaces and alter their hydrophobicity and hydrophilicity. Zhang et al.35 investigated the influence of laponite particles on froth stability in the presence of surfactant cetyltrimethylammonium bromide (CTAB). When the particle concentration was constant, the froth stability increased initially and then decreased with an increasing CTAB concentration. The results showed that the adsorption of CTAB on the surfaces of lithium soapstone increased with concentration at lower CTAB concentrations, leading to froth stability. However, CTAB formed reverse micelles on the particle surfaces at higher CTAB concentrations, causing a decrease in the particle hydrophobicity and froth stability. Sun et al.36 found that the surfactant molecules induced the particles to move to the interface and changed the structure of the surface layer at lower concentrations while promoting the particles to disperse well in the bulk solution at higher concentrations due to the increased hydrophilicity of the particle surface.

To the best of our knowledge, studies of the defoaming effects of surfactants on the overly stable froth generated by ultrafine chalcopyrite have never been reported. In this study, three different structured surfactants were used to modify the surfaces of ultrafine chalcopyrite particles and adjust the gas–liquid interfacial tension, with the aim of destabilizing the overly stable froth. The effects of the contact angle and interfacial tension on froth elimination were investigated, providing insights into the suitable surfactant structure for eliminating overly stable chalcopyrite froth in dewatering processes.

2 Materials and Methods

2.1 Materials

The mineral sample used in this study was chalcopyrite from Jiangxi Province, China. X-ray diffraction (XRD) analysis revealed a high purity of this chalcopyrite sample (Figure 1). The sample was ground to obtain a size fraction of less than 38 μm for flotation tests. According to the size distribution analysis, 50% of chalcopyrite particles were under 8.3 μm and 90% of particles were under 35.3 μm (Figure 2). XRD analysis was conducted using a D8 Advance (Bruker Corporation Inc., Germany), while size distribution was measured using a Bettersize 2600 (Bettersize Instruments Ltd., China). XPS profiles were recorded on a K-Alpha X-ray photoelectron spectrometer (Thermo Fisher Scientific Inc., USA).

Figure 1 XRD spectra of the chalcopyrite sample.

Figure 2 Size distribution of the ground chalcopyrite sample.

To understand the effect of surfactants on froth stability, three various structured surfactants were selected: sodium dodecyl sulfate (SDS, C12H25NaSO4, molecular weight: 288.37 g/mol) with a purity of 99%, sodium dodecylbenzenesulfonate (SDBS, C18H29NaSO3, molecular weight: 348.48 g/mol) with a purity of 95%, and pentadecafluorooctanoic acid (PFOA, C8HF15O2, molecular weight: 414.07 g/mol) with a purity of 96%. SDS, SDBS, and PFOA were purchased from Macklin Biochemical Co., Ltd. (Shanghai, China). EP (yellow liquid) serving as both an oily collector and a foamer was purchased from Beijing General Research Institute of Mining & Metallurgy (Beijing, China) with a purity of 99%. Figure 3 illustrates the structures of the three surfactants. Deionized (DI) water was obtained from a Millipore purification device with a resistivity over 18 MΩ × cm.

Figure 3 Structures of the surfactants: (a) SDS, (b) SDBS, and (c) PFOA.

2.2 Flotation Tests

The flotation tests were conducted through an XFG flotation machine (Jilin Exploration Machinery Inc., China). A 40 g portion of chalcopyrite and 1.3 L of DI water were added to a 1.5 L flotation cell and stirred at 970 rpm for 5 min. Then, 14 mg/L EP (serving as both a collector and a foamer) was added into the cell with a 2 min conditioning time at a flow rate of 1 L/min. Finally, the flotation froth was collected for 1 min for defoaming tests.

2.3 Defoaming Tests

The defoaming tests were quantified using the Bartsch method at room temperature (25 °C).37 The chalcopyrite froth collected from flotation was transferred to a 500 mL measuring cylinder in the presence and absence of various concentrations of surfactant. The cylinder was gently shaken three times, and then, the froth volumes were recorded before placing on a flat bench at room temperature for 20 min. Finally, the froth volumes were recorded again. The froth reduction efficiency (V – V0)/V0 as a criterion was employed to evaluate the defoaming performance, where V and V0 correspond to the froth volumes in the presence and absence of surfactant after settling for 20 min.

2.4 Interfacial Tension Measurements

The interfacial tension was measured using a Theta Flow tensiometer (Biolin Scientific Inc., Finland) by the pendant drop method in the absence and presence of various surfactants with different concentrations at room temperature (25 °C). This method has advantages such as minimal liquid usage, simplicity, and independence from contact angle effects.38 The principle lies in the suspension of a liquid at the pipet tip without detachment, where its size closely correlates to its weight and interfacial tension. The equation governing this measurement is

where W is the mass of the liquid drop, r is the radius of the pipet tip, and γ is the interfacial tension of the liquid. Subsequently, the resulting suspension after defoaming tests was collected and filtered through a 0.22 μm filter membrane to remove particles for interfacial tension measurements. Each measurement was repeated at least three times.

2.5 Contact Angle Measurements

The contact angle of the chalcopyrite surface was measured based on the sessile drop method by using a Theta Flow tensiometer (Biolin Scientific Inc., Finland) at room temperature (25 °C). After the defoaming tests, the resulting suspension was filtered and washed three times to remove excess surfactants. The particles were then dried at room temperature and pressed into pellets under a pressure of 15 MPa for further measurements. Contact angle measurements were conducted by dispensing a DI water droplet onto the presented chalcopyrite surface from a microsyringe. Each measurement was repeated at least three times at different points on each sample surface.

3 Results and Discussion

3.1 Defoaming of Chalcopyrite Froth

As shown in Figure 4, for the same surfactant, the froth reduction efficiency ((V – V0)/V0) improved with increasing concentration, especially for SDBS. The froth reduction efficiency of SDBS increased from 15% when no surfactant was used to 44% at an SDBS concentration of 2 mmol/L. Moreover, at an SDBS concentration of 4 mmol/L, the froth reduction efficiency of SDBS reached as high as 93.75%.

Figure 4 Plots of froth reduction efficiency versus surfactant concentration (SDBS, SDS, and PFOA).

Furthermore, when the surfactant concentration was less than 3 mmol/L, SDS exhibited a better defoaming performance compared with SDBS and PFOA, displaying a higher froth reduction efficiency (Figure 4). Conversely, when the surfactant concentration exceeded 3 mmol/L, SDBS demonstrated superior defoaming effectiveness over SDS and PFOA. Specifically, the froth reduction efficiency of SDBS was approximately 10% higher than that of SDS and 43% higher than that of PFOA at a surfactant concentration of 3 mmol/L. In conclusion, SDBS exhibited a higher defoaming effectiveness than SDS and PFOA at high concentrations, while SDS exhibited a slightly higher defoaming effectiveness compared to SDBS and PFOA at low concentrations.

3.2 Effect of Surfactants on the Interfacial Tension

Surfactants containing both hydrophobic and hydrophilic groups tend to adsorb at the interface. The hydrophobic groups within the surfactant spontaneously drive them from the liquid phase to the gas–liquid interface. As a result, the hydrophobic groups extend toward the gas phase while the hydrophilic groups toward the liquid phase, thereby altering the properties of the interface.39

As illustrated in Figure 5, the interfacial tension of the filtrate decreased with the addition of three various structured surfactants. At a concentration of 3.5 mmol/L, the lowest interfacial tension was recorded in the presence of the surfactant. Subsequently, the interfacial tension remained relatively constant as the surfactant concentration increased. It is because when the surfactant concentration is below the critical micelle concentration (CMC), the adsorption of surfactant at the gas–liquid interface increases with the rising surfactant concentration. Upon reaching the CMC, surfactant molecule adsorption saturates and then forms micelles as the surfactant concentration increases, resulting in no change in adsorption at the gas–liquid interface. Therefore, the ability of the surfactant to reduce interfacial tension is closely related to the adsorption at the interface.

Figure 5 Interfacial tension as a function of surfactant concentration (SDS, SDBS, and PFOA).

Fluorocarbon surfactants are a type of agent where hydrogen atoms in hydrocarbon surfactants are replaced by fluorine. The higher electronegativity and the weaker interactions between carbon–fluorine chains lead to a higher bond energy compared to carbon–hydrogen bonds, thus providing fluorocarbon surfactants with lower interfacial tension than hydrocarbon surfactants.40 Açışlı et al.41 investigated surfactants with five different hydrocarbon chain lengths and found a lower interfacial tension with longer chains. These are consistent with the experimental results (Figure 5): the interfacial tension of PFOA was lower than those of hydrocarbon surfactants (SDS and SDBS), and the interfacial tension of SDBS was lower than that of SDS.

3.3 Effect of Surfactants on the Wettability of Chalcopyrite Particles

To investigate the influence of surfactants on the wettability of chalcopyrite surfaces, contact angle measurements were conducted at room temperature (25 °C) with an EP concentration of 14 mg/L. The correlation between the dosages of three surfactants and the contact angles of chalcopyrite surfaces was examined. Kenzhaliyev et al.42 found that SDS can adsorb onto the surfaces of chalcopyrite, thereby reducing the contact angle of chalcopyrite surfaces to improve the wettability of the mineral surface, which is consistent with the impact of SDBS, SDS, and PFOA in this experimental results in general. As shown in Figure 6, the contact angle of the chalcopyrite surfaces exhibited a decreasing trend as the surfactant concentration increased. For SDBS, SDS, and PFOA, when the surfactant concentration was below 2 mmol/L, the decrease in the contract angle was relatively minor. However, when the surfactant concentration exceeded 2 mmol/L, the trend shifted dramatically, with the contact angle of the chalcopyrite surfaces showing a noticeable decrease along with an increase in surfactant concentration. To confirm the adsorption of the surfactant on the surface of chalcopyrite particles, XPS spectra were recorded and analyzed. According to the XPS C 1s spectrum, the total spectral content of XPS of C (Figure 7b) after the addition of surfactants at a concentration of 3 mmol/L was higher than that without the addition of surfactants, indicating that the surfactants were successfully modified on the surface of the chalcopyrite particles.

Figure 6 Contact angle of the surfactant-modified chalcopyrite surface as a function of surfactant concentration (PFOA, SDS, and SDBS).

Figure 7 XPS spectra of the chalcopyrite in the absence and presence of surfactants: (a) full-scan spectrum and (b) C 1s spectrum.

The contact angle of the chalcopyrite surfaces was 70° in the absence of a surfactant. Upon addition of a surfactant concentration of 2 mmol/L, the contact angle of the chalcopyrite surfaces modified by SDS decreased to 66.86°, while those modified by SDBS and PFOA decreased to 67.5 and 68.1°, respectively. As the surfactant concentration increased to 4 mmol/L, SDBS showed a higher impact on reducing the contact angle of the chalcopyrite surfaces, decreasing it to 37.62°, whereas the SDS- and PFOA-modified chalcopyrite surface contact angles decreased to 42.12 and 47.59°, respectively. Han et al.43 found that SDBS exhibited a significant steric hindrance in its structure through molecular dynamic simulations, which hinders the approach of other molecules at low concentrations. This is consistent with the effect of SDBS on the contact angle of the chalcopyrite surfaces at low concentrations, which could be caused by the steric hindrance of SDBS that impedes the approach of chalcopyrite particles and SDBS molecules to each other at low concentrations.

Because it contains more carbon atoms and benzene ring groups, SDBS possesses a stronger hydrophobicity compared to SDS. The hydrophobic interaction between SDBS and hydrophobic chalcopyrite is stronger compared to that between SDS and hydrophobic chalcopyrite. As the concentration of SDBS continues to increase, the hydrophobic groups of SDBS are promoted to adsorb onto the hydrophobic surfaces of chalcopyrite through the hydrophobic interaction, thereby reducing the contact angle of the chalcopyrite surfaces. Therefore, when the surfactant concentration exceeded 3 mmol/L, SDBS demonstrated a higher defoaming effectiveness over SDS and PFOA. However, due to the steric hindrance of SDBS, it might exhibit a lower adsorption capacity onto chalcopyrite particles than SDS at low surfactant concentrations, leading to a smaller reduction in contact angle compared to that of SDS-modified chalcopyrite surfaces. Nevertheless, as the concentration increased, the adsorption capacity of SDBS to chalcopyrite particles became stronger due to the hydrophobic interaction, resulting in lower contact angles.

The surface of chalcopyrite is typically negatively charged, and the carboxyl group of PFOA is also negatively charged.44 Therefore, PFOA can adsorb onto the negatively charged surfaces of chalcopyrite through electrostatic interaction. As the concentration of PFOA increased, the contact angle on the chalcopyrite surfaces gradually decreased. However, due to the lipophobic nature of the fluorocarbon tail of PFOA, which is attributed to the lower polarizability of fluorocarbon,45 PFOA faces difficulty in adsorbing onto the chalcopyrite surfaces modified with an oily collector (EP). Hence, the reduction in the contact angle of chalcopyrite surfaces modified with PFOA was smaller than that of the chalcopyrite surfaces modified with SDS and SDBS, regardless of whether they were at high or low concentrations.

It is interesting to note that at the same contact angle (47°), the concentrations of SDBS, SDS, and PFOA were 3, 3.5, and 4 mmol/L, respectively, with corresponding froth reduction efficiencies of 81, 77.5, and 75%. This suggests that the defoaming efficiency was influenced not only by the contact angle but also by the interfacial tension, which is another factor influenced by surfactants.

3.4 Effect of the Contact Angle of Chalcopyrite Particles on Defoaming Performance

Previous studies have indicated a correlation between immersion depth and contact angle.46 As depicted in Figure 8, the immersion depth (R × (1 – cos θ)) of a chalcopyrite particle immersed in the gas phase at the gas–liquid interface becomes deeper as the contact angle (θ) increases. Figure 9 illustrates the plots of the froth reduction efficiency factor against cos θ, showing good linearity between the froth reduction efficiency and cos θ (RSDS2 = 0.97, RSDBS2 = 0.98, and RPFOA2 = 0.98), respectively. Therefore, the immersion depth (R × (1 – cos θ)) decreases accordingly as the contact angle decreases, and chalcopyrite particles detach from the surfaces of the bubbles to the liquid phase, thus improving surface wettability and reducing froth stability,11 leading to higher froth reduction efficiency.

Figure 8 Chalcopyrite particle partially immersed in the gas phase at the gas–liquid interface.

Figure 9 Linear correlations between froth reduction efficiency and cos θ with the addition of different surfactants: (a) SDS, (b) SDBS, and (c) PFOA and (d) a comparison of the three surfactants on froth reduction efficiency.

The experimental results reveal that different surfactants exhibited varying defoaming effectiveness under the same immersion depth (Figure 9d). When considering the same immersion depth, the froth reduction efficiency ranking was as follows: SDS > SDBS > PFOA. This ranking corresponds to the order of interfacial tension (SDS > SDBS > PFOA), which is another factor influenced by surfactants, where a decrease in interfacial tension led to a reduction in froth reduction efficiency. With the decrease in interfacial tension, the froth became more stable possibly through hydrogen bonding, van der Waals forces, and steric hindrance effects between molecules, leading to water molecule rearrangement in the interface region.31 Therefore, this demonstrates that the reduction of interfacial tension had an adverse effect on defoaming.

4 Conclusions

In this study, three different structured surfactants were employed to modify the surfaces of ultrafine chalcopyrite particles and adjust the gas–liquid interfacial tension, aiming to eliminate the overly stable froth. At low concentrations, SDS exhibited the highest defoaming effectiveness followed by SDBS and PFOA. Conversely, at high concentrations, SDBS displayed the highest defoaming effectiveness followed by SDS and PFOA. This phenomenon closely correlated with the contact angle of the surfactant-modified chalcopyrite surfaces and the interfacial tension at the gas–liquid interface, with the contact angle playing a dominant role. The contact angle measurements indicated that the immersion depth decreased linearly as the contact angle decreased, allowing the chalcopyrite particles to detach from the surfaces of the bubbles to the liquid phase. This detachment improved surface wettability and reduced froth stability, leading to a higher froth reduction efficiency. Furthermore, the addition of SDBS significantly reduced the contact angle at high concentrations due to its strong hydrophobicity and adsorption capacity to chalcopyrite particles, which could reduce the contact angle from 70 to 37.62°, achieving a froth reduction efficiency as high as 93.75%. Moreover, the froth reduction efficiency of SDBS was approximately 10% higher than that of SDS and 43% higher than that of PFOA at a surfactant concentration of 3 mmol/L. Interfacial tension measurements revealed that the reduction of the interfacial tension at the gas–liquid interface adversely affected the defoaming effectiveness. However, all three surfactants were capable of reducing interfacial tension and stabilizing stable foam, with PFOA being the most effective at reducing interfacial tension. In summary, the addition of surfactants, which can improve the wettability of chalcopyrite particles, may be suitable for defoaming.

The authors declare no competing financial interest.

Acknowledgments

This work was supported by Jiangxi Province Major Science and Technology R&D Special Project (20232ACE01010) and Jiangxi Province Double Thousand Plan (No. S2021LQCQ0128).
==== Refs
References

Mudd G. M. ; Jowitt S. M. Growing global copper resources, reserves and production: Discovery is not the only control on supply. Econ Geol. 2018, 113 , 1235–1267. 10.5382/econgeo.2018.4590.
Castellon C. I. ; Toro N. ; Galvez E. ; Robles P. ; Leiva W. H. ; Jeldres R. I. Froth Flotation of Chalcopyrite/Pyrite Ore: A Critical Review. Materials. 2022, 15 , 6536 10.3390/ma15196536.36233879
Shean B. J. ; Cilliers J. J. A review of froth flotation control. Int. J. Miner. Process. 2011, 100 , 57–71. 10.1016/j.minpro.2011.05.002.
Neethling S. ; Brito-Parada P. Predicting flotation behaviour–The interaction between froth stability and performance. Miner. Eng. 2018, 120 , 60–65. 10.1016/j.mineng.2018.02.002.
Barbian N. ; Hadler K. ; Cilliers J. J. The froth stability column: measuring froth stability at an industrial scale. Miner. Eng. 2006, 19 , 713–718. 10.1016/j.mineng.2005.09.021.
Fang J. ; Ge Y. ; Yu J. Effects of particle size and wettability on froth stability in a collophane flotation system. Powder Technol. 2021, 379 , 576–584. 10.1016/j.powtec.2020.11.028.
Ahmadi R. ; Khodadadi D. A. ; Abdollahy M. ; Fan M. Nano-microbubble flotation of fine and ultrafine chalcopyrite particles. Int. J. Min. Sci. Techno. 2014, 24 , 559–566. 10.1016/j.ijmst.2014.05.021.
Chen L. ; Xiong T. ; Xiong D. ; Yang R. ; Peng Y. ; Shao Y. ; Xu J. ; Zeng J. Pulsating HGMS for industrial separation of chalcopyrite from fine copper-molybdenun co-flotation concentrate. Miner. Eng. 2021, 170 , 106967 10.1016/j.mineng.2021.106967.
Bilal M. ; Park I. ; Ito M. ; Hassan F. U. ; Aikawa K. ; Jeon S. ; Hiroyoshi N. Carrier flotation using coarse pyrite for improving the recovery of finely ground chalcopyrite: Development of post-process of carrier flotation to separate finely ground chalcopyrite particles from coarse pyrite particles. Minerals. 2023, 13 , 916 10.3390/min13070916.
Zhang N. ; Chen X. ; Nicholson T. ; Peng Y. The effect of froth on the dewatering of coals–An oscillatory rheology study. Fuel. 2018, 222 , 362–369. 10.1016/j.fuel.2018.02.168.
Zhang N. ; Chen X. ; Peng Y. Effects of froth properties on dewatering of flotation products–A critical review. Miner. Eng. 2020, 155 , 106477 10.1016/j.mineng.2020.106477.
Jeldres R. I. ; Uribe L. ; Cisternas L. A. ; Gutierrez L. ; Leiva W. H. ; Valenzuela J. The effect of clay minerals on the process of flotation of copper ores-A critical review. Appl. Clay Sci. 2019, 170 , 57–69. 10.1016/j.clay.2019.01.013.
Pugh R. Foaming, foam films, antifoaming and defoaming. Adv. Colloid Interfac. 1996, 64 , 67–142. 10.1016/0001-8686(95)00280-4.
Kang S. ; Li R. ; Wu Z. ; Guo S. ; Gao Y. Effective improvement of defoaming efficiency using foam breaker with synthetic sponge cylinders in foam fractionation. Chem. Eng. Process. 2016, 106 , 26–32. 10.1016/j.cep.2016.05.001.
Raj A. ; Sathyan D. ; Mini K. Physical and functional characteristics of foam concrete: A review. Constr. Build. Mater. 2019, 221 , 787–799. 10.1016/j.conbuildmat.2019.06.052.
McGee J. B. Selecting chemical defoamers and antifoams. Chem. Eng. 1989, 96 , 131.
Cevada E. ; Hernández E. ; Flores C. ; Zavala G. ; Álvarez F. ; Vázquez F. Novel silicon free defoaming agents, based on alkylacrylates, for petroleum: Effect of the molecular weight on their efficiency. Fuel. 2020, 278 , 118401 10.1016/j.fuel.2020.118401.
Kougias P. G. ; Boe K. ; Angelidaki I. Solutions for foaming problems in biogas reactors using natural oils or fatty acids as defoamers. Energy Fuels. 2015, 29 , 4046–4051. 10.1021/ef502808p.
Denkov N. D. Mechanisms of foam destruction by oil-based antifoams. Langmuir. 2004, 20 , 9463–9505. 10.1021/la049676o.15491178
Joshi K. ; Jeelani S. ; Blickenstorfer C. ; Naegeli I. ; Oliviero C. ; Windhab E. J. Nonionic block copolymer antifoams. Langmuir. 2006, 22 , 6893–6904. 10.1021/la0600797.16863236
Perez R. F. ; Santos I. C. V. M. ; Macedo V. P. ; Mendes M. T. ; Ramalho J. B. V. S. ; Junior O. K. ; Mansur C. R. E. Surface activity of PDMS silicone oil applied as petroleum antifoamer. J. Appl. Polym. Sci. 2024, 141 , e55031 10.1002/app.55031.
Luo Q. ; Deng Y. ; Zhu J. ; Shin W.-T. Foam control using a foaming agent spray: a novel concept for flotation deinking of waste paper. Ind. Eng. Chem. Res. 2003, 42 , 3578–3583. 10.1021/ie021018g.
Mesa D. ; Brito-Parada P. R. Scale-up in froth flotation: A state-of-the-art review. Sep. Purif. Technol. 2019, 210 , 950–962. 10.1016/j.seppur.2018.08.076.
Nowosielska A. M. ; Nikoloski A. N. ; Parsons D. F. Interactions between coarse and fine galena and quartz particles and their implications for flotation in NaCl solutions. Miner. Eng. 2022, 183 , 107591 10.1016/j.mineng.2022.107591.
Norori-McCormac A. ; Brito-Parada P. ; Hadler K. ; Cole K. ; Cilliers J. The effect of particle size distribution on froth stability in flotation. Sep. Purif. Technol. 2017, 184 , 240–247. 10.1016/j.seppur.2017.04.022.
Wang H. ; Brito-Parada P. The role of microparticles on the shape and surface tension of static bubbles. J. Colloid Interface Sci. 2021, 587 , 14–23. 10.1016/j.jcis.2020.11.094.33360886
Liang L. ; Li Z. ; Peng Y. ; Tan J. ; Xie G. Influence of coal particles on froth stability and flotation performance. Miner. Eng. 2015, 81 , 96–102. 10.1016/j.mineng.2015.07.004.
Dippenaar A. The destabilization of froth by solids. I. The mechanism of film rupture. Int. J. Miner. Process. 1982, 9 , 1–14. 10.1016/0301-7516(82)90002-3.
Wang J. ; Nguyen A. V. ; Farrokhpay S. A critical review of the growth, drainage and collapse of foams. Adv. Colloid Interfac. 2016, 228 , 55–70. 10.1016/j.cis.2015.11.009.
Johansson G. ; Pugh R. The influence of particle size and hydrophobicity on the stability of mineralized froths. Int. J. Miner. Process. 1992, 34 , 1–21. 10.1016/0301-7516(92)90012-L.
Qiu H. ; Wu B. ; Deng J. ; Sun X. ; Hu M. ; Cai J. ; Zheng C. The effect of collectors on froth stability of frother: Atomic-scale study by experiments and molecular dynamics simulations. J. Mol. Liq. 2022, 364 , 120035 10.1016/j.molliq.2022.120035.
Pichot R. ; Spyropoulos F. ; Norton I. Competitive adsorption of surfactants and hydrophilic silica particles at the oil–water interface: Interfacial tension and contact angle studies. J. Colloid Interface Sci. 2012, 377 , 396–405. 10.1016/j.jcis.2012.01.065.22487228
Pugh R. J. Bubble and foam chemistry; Cambridge University Press: 2016.
Yang B. ; Yin W. ; Zhu Z. ; Sun H. ; Sheng Q. ; Fu Y. ; Yao J. ; Zhao K. Differential adsorption of hydrolytic polymaleic anhydride as an eco-friendly depressant for the selective flotation of apatite from dolomite. Sep. Purif. Technol. 2021, 256 , 117803 10.1016/j.seppur.2020.117803.
Zhang S. ; Lan Q. ; Liu Q. ; Xu J. ; Sun D. Aqueous foams stabilized by Laponite and CTAB. Colloid. Surface. A 2008, 317 , 406–413. 10.1016/j.colsurfa.2007.11.010.
Sun Q. ; Li Z. ; Wang J. ; Li S. ; Li B. ; Jiang L. ; Wang H. ; Lü Q. ; Zhang C. ; Liu W. Aqueous foam stabilized by partially hydrophobic nanoparticles in the presence of surfactant. Colloid. Surface. A 2015, 471 , 54–64. 10.1016/j.colsurfa.2015.02.007.
Jha B. ; Patist A. ; Shah D. Effect of antifoaming agents on the micellar stability and foamability of sodium dodecyl sulfate solutions. Langmuir. 1999, 15 , 3042–3044. 10.1021/la981523b.
Soori T. ; Rassoulinejad-Mousavi S. M. ; Zhang L. ; Rokoni A. ; Sun Y. A machine learning approach for estimating surface tension based on pendant drop images. Fluid Phase Equilib. 2021, 538 , 113012 10.1016/j.fluid.2021.113012.
Bzdek B. R. ; Reid J. P. ; Malila J. ; Prisle N. L. The surface tension of surfactant-containing, finite volume droplets. P. Natl. Acad. Sci. USA 2020, 117 , 8335–8343. 10.1073/pnas.1915660117.
Chen X. ; Gao J. ; Deng C. ; Ge S. ; Fan C. ; Zhang W. Characterization of the wetting properties of ionic liquids on lignite surfaces: Molecular dynamics simulations. J. Mol. Liq. 2023, 389 , 122886 10.1016/j.molliq.2023.122886.
Açışlı Ö. ; Karaca S. ; Gürses A. Investigation of the alkyl chain lengths of surfactants on their adsorption by montmorillonite (Mt) from aqueous solutions. Appl. Clay Sci. 2017, 142 , 90–99. 10.1016/j.clay.2016.12.009.
Kenzhaliyev B. ; Ketegenov T. ; Kamunur K. ; Batkal A. ; Nadirov R. Efficient copper recovery from chalcopyrite using an ≪Isopropanol–Sulfuric Acid–Sodium Dodecyl Sulfate≫ system. Minerals. 2023, 13 , 1346 10.3390/min13101346.
Han D. ; Wang Y. ; Yang Y. ; Gong T. ; Chen Y. ; Gong J. Revealing the role of a surfactant in the nucleation and crystal growth of thiamine nitrate: experiments and simulation studies. CrystEngComm. 2019, 21 , 3576–3585. 10.1039/C9CE00325H.
Li Y. ; Kawashima N. ; Li J. ; Chandra A. ; Gerson A. R. A review of the structure, and fundamental mechanisms and kinetics of the leaching of chalcopyrite. Adv. Colloid Interfac. 2013, 197 , 1–32. 10.1016/j.cis.2013.03.004.
Štěpánek M. ; Škvarla J. ; Uchman M. ; Procházka K. ; Angelov B. ; Kováčik L. ; Garamus V. M. ; Mantzaridis C. ; Pispas S. Wormlike core–shell nanoparticles formed by co-assembly of double hydrophilic block polyelectrolyte with oppositely charged fluorosurfactant. Soft Matter. 2012, 8 , 9412–9417. 10.1039/c2sm25588j.
Levine S. ; Bowen B. D. ; Partridge S. J. Stabilization of emulsions by fine particles I. Partitioning of particles between continuous phase and oil/water interface. Colloids Surf. 1989, 38 , 325–343. 10.1016/0166-6622(89)80271-9.
