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Article

Mechanisms of Fine Mud Covering and Enhanced Dispersion for a Rutile Middling

1
State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, School of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, China
2
Faculty of Land Resource Engineering, Kunming University of Science and Technology, Kunming 650093, China
3
School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan 430070, China
*
Author to whom correspondence should be addressed.
Metals 2025, 15(10), 1074; https://doi.org/10.3390/met15101074
Submission received: 14 August 2025 / Revised: 19 September 2025 / Accepted: 21 September 2025 / Published: 25 September 2025
(This article belongs to the Special Issue Advances in Sustainable Utilization of Metals: Recovery and Recycling)

Abstract

Electric separation is usually adopted to separate and purify rutile and zircon. However, fine mud covering over the target minerals either reduces the conductivity of rutile or improves the conductivity of zircon. Therefore, the conductivity difference between zircon and rutile becomes smaller, leading to the difficulty of separation and purification of both minerals. In this paper, the mechanisms of fine mud covering and enhanced dispersion for a rutile middling were illustrated by theoretical calculations of Derjaguin–Landau–Verwey–Overbeek (DLVO) and the extended DLVO (EDLVO), respectively. The fine mud was initially characterized by chemical multi-element analysis, X-ray diffractometer (XRD) analysis, electron probe micro analysis (EPMA), and laser particle size analyzer. The results showed that the gangue was mainly composed of goethite, quartz, calcite, and kaolinite and the average particle size of the fine mud reached 11.06 μm. The DLVO theoretical calculation revealed that the covering ability of fine-grained gangue ranked as follows: quartz < goethite < kaolinite < calcite. Compared with the zircon, the fine-grained gangue was more likely to cover the surface of rutile. The EDLVO theoretical calculation suggested that the addition of sodium silicate or sodium hexametaphosphate promoted detachment of the gangue from the surface of rutile and zircon and the shedding order was quartz > kaolinite > calcite > goethite. Moreover, the sodium hexametaphosphate had a better dispersion effect than the sodium silicate.

1. Introduction

Titanium and zirconium are refractory metals and exhibit excellent physical and chemical properties. They are used in various fields, including the chemical, military, and aerospace industries [1,2]. Rutile possesses a high TiO2 content, thus attracting significant attention. Zircon is a common mineral that holds substantial industrial value [3]. The global titanium–zirconium resources, which are concentrated in the Oceania and Africa, are mainly coastal sedimentary placer deposits with high economic value [4]. In contrast, the overall reserves of rutile and zircon in China are relatively small, and the ore is characterized by low grades. Moreover, the target minerals exhibit small grain size and complex mineral composition. Thus, they are difficult to separate and purify [5].
Zirconium–titanium marine placer in China is mainly distributed in the southeast coastal areas such as Hainan Island, southern coast of Guangxi, and Fujian coast [6]. In the mining process of coastal sand, bulldozers are commonly employed to transport ore along the shoreline. The collected ore undergoes a combined treatment of screening and gravity separation process. For sand deposits located in offshore areas, mining is typically conducted by using specialized sand dredgers, which are equipped with mineral processing equipment that allow for pre-concentrating the Ti–Zr bearing minerals [7]. Generally, the marine environment is characterized by complexity and variability caused by waves, tides, and ocean currents. The mineral particles within the seabed sand deposits are continuously disturbed and transported, leading to the formation of finer mud [8]. On the other hand, the ore will be broken into smaller particles, increasing the amounts of slime during the processes of crushing and grinding [9].
The fine mud often covers over the surfaces of rutile and zircon, altering the conductive differences at the surface. Thus, separation performance of rutile and zircon was not satisfactory [10,11]. Moreover, the fine mud easily forms dust during the electric separation, which not only causes severe air pollution in the processing plant but also poses potential health risks to workers [12]. Therefore, seeking to solve the adverse effects of slime on the separation of rutile and zircon is of significant importance for advancing the processing technology in the titanium–zirconium industry. Guangxi Ubridge New Material Technology Co., Ltd., in Fangchenggang City, China, is committed to the production of rutile and zircon products. The feeding was imported from Australia, where a rutile middling approximately containing 30.0% TiO2 and 5.0% ZrO2 was produced [13]. A combined process of desliming–magnetic separation–gravity separation–drying–electric separation was employed for treating the rutile middling. However, the desliming unit faced low desliming efficiency. Even if the existing scrubber could well remove the fine gangue from the surface of rutile and zircon, the detached gangue would cover over their surface again due to the high surface activity. Finally, poor electric separation performances of rutile and zircon were obtained. Therefore, it is essential to investigate the mineralogical characteristics of fine mud and its interaction mechanism with rutile and zircon. Derjaguin–Landau–Verwey–Overbeek (DLVO) theory and the extended DLVO (EDLVO) theory play an important role in understanding the particle interaction and predicting the particle dispersion by introducing surfactants, further optimizing the beneficiation process [14].
In the reported literature, there was an extreme lack of information about fine mud which originated from the beach placer. In this paper, the slime was investigated by chemical analyses, X-ray diffractometer (XRD) analysis, electron probe micro analysis (EPMA), and laser particle size analyzer. Based on the properties of the slime, the van der Waals interaction energy (VW), electrostatic interaction energy (VE), and the total interaction energy (VT) between the rutile/zircon and gangue were calculated by using the DLVO theory to elucidate the aggregation mechanisms. Subsequently, the VW′, VE′, polar interface interaction energy (VH), and VT′ between the rutile/zircon and gangue were investigated in the presence of sodium hexametaphosphate (SHMP) and sodium silicate (SS) by the EDLVO theory to reveal the mechanisms of enhanced dispersion. The goal was to find a new method for efficiently removing fine mud from the rutile middling.

2. Materials and Methods

2.1. Materials

2.1.1. The Slime

To investigate the properties of slime which had been separated from the rutile middling by the existing scrubber–desliming process, X-ray fluorescence spectroscopy (XRF) and chemical multi-element analyses were performed. The results are shown in Table 1 and Table 2. From Table 1, it becomes known that the main metal elements in the slime are iron, aluminum, calcium, titanium, and zirconium, and the main non-metallic element is silicon. In addition, trace rare earth elements such as lanthanum, cerium, and yttrium are also present. According to Table 2, the contents of Fe, Ti, and Zr are 16.48%, 2.70%, and 1.78%, respectively, indicating that part of valuable metals is lost in the slime. In addition, the content of Si reaches 7.23%, suggesting that the minerals exist in the form of aluminosilicates or quartz.
Figure 1 shows XRD analysis result of the slime. It is seen that the main minerals in the slime include goethite (FeO(OH)), rutile (TiO2), quartz (SiO2), calcite (CaCO3), and kaolinite (Al4[Si4O10](OH)8). The signal of zircon was not found due to the low zirconium content.
Figure 2 shows EPMA-mapping analyses results of the slime and Table 3 presents the EDS analyses results. It is known that the particles located at position 1, position 2, and position 3 were quartz, Fe-bearing rutile, and zircon, respectively. There were a few Fe-bearing rutile and zircon, which agreed with the results of chemical analyses. The particles located at position 4 and position 5 were aluminosilicates, e.g., kaolinite. In addition, it is found that the aluminosilicate particles exhibited the large size, which was explained by the fact that the slime interacted with each other and then aggregated after dehydration and drying. The results further suggest that the slime presented high surface activity. Combined with the XRD analyses results, the main mineral constituents of the fine mud were quartz, goethite, calcite, and kaolinite.
Figure 3 shows the particle size analysis result of the slime. It is known that average particle size of the slime reached 11.06 μm. Thus, particle sizes of the goethite, quartz, calcite, and kaolinite were set as 11.06 μm in the subsequent calculations.

2.1.2. Experimental Materials

In the DLVO and EDLVO theoretical calculations, it is necessary to obtain key parameters such as the surface wettability and surface potentials of minerals. Accordingly, contact angle and zeta potential measurements were conducted on these minerals including the rutile, zircon, quartz, calcite, kaolinite, and goethite, in which the rutile and zircon were provided by the plant in Guangxi Ubridge New Material Technology Co., Ltd., and the other minerals were purchased from Yunbao Studio in Yunnan (Kunming), China. The XRD analyses results of these minerals are presented in Figure 4. It is observed that there were no other signals in every diffraction pattern, indicating that every mineral exhibited a high purity.

2.2. Experimental Methods

2.2.1. Zeta Potential Measurement

Zeta potentials of the rutile, zircon, goethite, quartz, calcite, and kaolinite before and after treatment with SS or SHMP were measured using a NanoParticle Size and Zeta Potential Analyzer (Zetasizer 3000HS, Malvern Co., Ltd., Worcester, United Kingdom). The background electrolyte, which consisted of 40 mL of 1 × 10−3 mol/L KCl solution, was added into a beaker containing 30.0 mg of powder sample at a particle size less than 2 μm for each measurement. The mixture was magnetically stirred and allowed to stand for 10 min. The upper solution was then collected using a glass syringe for the zeta potential measurement. Subsequently, 1 × 10−4 mol/L SS or SHMP was introduced. After stirring, the pH value was fixed to be 7.0. Each test was repeated five times, and the average value was taken as the final value.

2.2.2. Contact Angle Tests

Pure minerals of rutile, zircon, quartz, goethite, kaolinite, and calcite were ground to a particle size of −74 + 37 μm. The static contact angle measurements were performed with a surface tension tester K 100 KRUSS (KRUS Scientific Instruments Shanghai Co., Ltd., Shanghai, China). Approximately 2.0 g of pure mineral sample was placed into a beaker with 40 mL deionized water each time, stirred for 2 min, and then the surfactants including SHMP and SS were added and further stirred for 3 min. After that, the pulp was filtrated and dried in a vacuum drying oven. The capillary constant was measured by using pure mineral and anhydrous ethanol liquid. The liquid was replaced with deionized water or glycerol for the contact angle experiments. Three experiments were repeated and the average value was taken as the final value. The detection principle is Washburn dynamic pressure method and the contact angle data was fitted by Advance software (version: 1.8.0.4). The equation is as follows:
m 2 t = ρ c σ cos θ η  
where m is the mass (g), c is capillary constant (mm2/s2) of the powder, σ is the surface tension of liquid (mN/m), η is liquid viscosity (mPa·s), ρ is density of the wetting liquid (g/mL), t is flow time (s), θ is powder contact angle (°).

2.2.3. Other Measurements

The mineral phase was analyzed by using an XRD analyzer (D/MAX 115 2200, Rigaku, Kyoto, Japan) operated at 40 kV voltage and 40 mA tube current. The scanning range was set from 10° to 90° with a scanning speed of 5°/min. EPMA analysis was conducted by using an EPMA-1720 series instrument (Shimadzu Corporation) equipped with four wavelength-dispersive spectrometer (WDS) detectors to characterize the chemical composition of minerals in the slime. Particle size distribution of the slime was determined by using a BT-9300Z laser particle size analyzer (Dandong Better Instrument Co., Ltd., Dandong, China).

2.3. Theoretical Calculation Methods of DLVO and EDLVO

To investigate the interaction mechanisms between gangue including quartz, calcite, kaolinite, and goethite and the target minerals including rutile and zircon, eight research systems were established: rutile/zircon–quartz, rutile/zircon–goethite, rutile/zircon–calcite, and rutile/zircon–kaolinite. When there was no addition of reagents, the DLVO theory was applied to calculate the VT between the two particles, as expressed by: VT = VW + VE. When the SS or SHMP was added, the EDLVO theoretical model was used. In this case, the VT between the particles was given by VT′ = VW′ + VE′ + VH.
To simplify the calculation, the adsorption layer was not considered. The VW between particles is calculated by using the following [15]:
V W = A 132 6 H R 1 R 2 R 1 + R 2
where H represents the interaction distance (nm) between the rutile/zircon and gangue in the ore; R1 and R2 correspond to the particle sizes of the rutile/zircon and gangue particles, respectively; A132 is the effective Hamaker constant (J) of mineral in aqueous solution.
Based on our previous research results and the statistical analysis method of ore particle size [13,16], the average particle sizes of rutile and zircon were determined as 99.416 μm and 87.564 μm, respectively. The value of A132 is calculated as the following:
A 132 = ( A 11 A 33 ) ( A 22 A 33 )
where A11, A22, and A33 represent the Hamaker constants of rutile/zircon particle, quartz/kaolinite/calcite/goethite particle, and water in the vacuum, respectively. The Hamaker constants are presented in Table 4.
The calculation formula for the VE is presented in the following [24,25]:
V E = π ε 0 ε r R 1 R 2 R 1 + R 2 2 φ 1 φ 2 ln 1 + e k H 1 e k H + φ 1 2 + φ 2 2 ln 1 e 2 κ H
Among them, φ1 and φ2 correspond to the surface potentials (mV) of rutile/zircon particles and the gangue particles, respectively; ε0 and εr are the permittivity of vacuum and water, respectively, and their values were separately taken as 8.854 × 10−12 C2 J−1 m−1 and 78.5; κ (nm−1) is reciprocal of the Debye length and it is calculated for a 1:1 type electrolyte as following:
κ = c 0.304
where c represents the KCl concentration, which is taken as 0.001 mol/L.
The adsorption of various surfactants onto mineral surfaces unavoidably induces surface charge [26]. Table 5 shows the zeta potentials of various minerals before and after adding SS or SHMP. It is known that surface potentials of minerals shifted toward more negative values, indicating that the reagent could interact with the mineral surface.
The polar interfacial interaction energy is calculated as following [27]:
V H = 2 π R 1 R 2 R 1 + R 2 h 0 V H 0 e x p H 0 H h 0
where h0 denotes the decay length, which is taken as 1 nm [28]; H0 is contact distance (0.2 nm) between the two particles in an equilibrium state; V H 0 represents the polar interfacial interaction energy constant (mJ·m−2) between the two particles and it is calculated as the following [29]:
V H 0 = 2 γ 3 + γ 1 + γ 2 γ 3 + γ 3 γ 1 + + γ 2 + γ 3 + γ 1 + γ 2 γ 1 γ 2 +
where γ 1 + , γ 2 + , and γ 3 + represent electron acceptor components of the rutile/zircon, gangue, and water, respectively, whereas γ 1 , γ 2 and γ 3 represent electron donor components.
Most of the minerals were viewed as unipolar minerals when the water was considered as medium. Therefore, both of the γ 1 + and γ 2 + are taken as zero and both of the γ 3 + and γ 3 are taken as 25.5 mJ·m−2. The V H 0 can be further simplified as following [27]:
V H 0 = 2 γ 3 + γ 1 + γ 2 2 γ 3
where γ 1 and γ 2 can be obtained by using the following formula:
1 + cos θ γ L = 2 γ s d γ L d + γ s γ L +
where θ represents the contact angle between mineral and the liquid phase; γL, γ L d , γ L + , and γ L denote the total surface energy of liquid, dispersion component of surface energy, electron acceptor component and electron donor component, respectively; γ s d , γ s + , and γ s correspond to the dispersion component, electron acceptor component, and electron donor component of the solid surface energy, respectively.
According to Equation (9), the γ s d and γ s can be obtained by introducing two kinds of liquids including water and glycerol. In the reported literature [30], the surface tension parameters of water were as follows: γ w = 72.8 mJ·m−2, γ w d = 21.8 mJ·m−2, γ w + = γ w = 25.5 mJ·m−2. For the glycerol, parameters are as follows: γ = 64 mJ·m−2, γ g d = 34 mJ·m−2, γ g + = 3.92 mJ·m−2, γ g = 57.4 mJ·m−2. The testing results of contact angles for various minerals after treating with SS and SHMP wet by the water or glycerol are presented in Table 6 and Table 7.

3. Results and Discussions

3.1. DLVO Theoretical Calculation

3.1.1. Interaction Energy Between Rutile and Gangue

Figure 5 shows the interaction energy between the rutile and gangue. In Figure 5a, the VW between the rutile and gangue was negative when the interparticle distance ranged from 0.2 to 10 nm, indicating that the van der Waals forces promoted attraction of the rutile with the gangue. With increasing the interparticle distance, the VW gradually decreased to zero. From Figure 5b, the VE between the rutile and quartz/kaolinite/goethite was positive, whereas the VE between the rutile and calcite was negative, suggesting that the electrostatic force caused the rutile repel the quartz, kaolinite, and goethite, but attract with the calcite. According to Figure 5c, the VT between the rutile and calcite/kaolinite/goethite was negative within the particle distance range of 0.2–3.0 nm, indicating that these particles exhibited attraction with the rutile. Meanwhile, the total interaction energy between rutile and quartz was positive, revealing that there was a mutual repulsion between the quartz and rutile. Therefore, these minerals such as calcite, kaolinite, and goethite, except for the quartz, were prone to adhere to the surface of rutile. Moreover, it is known that the covering capacity of gangue was as follows: quartz < goethite < kaolinite < calcite.

3.1.2. Interaction Energy Between the Zircon and Gangue

Figure 6 shows the interaction energy between the zircon and gangue. In Figure 6a,b, the VW and VE between the zircon and gangue exhibited the same trends as the rutile system. In Figure 6c, the VT for the zircon–goethite and for the zircon–kaolinite became positive when the particle distance exceeded 0.8 nm and 1.8 nm, respectively, indicating that the interaction force between zircon and goethite/kaolinite varied from attraction to repulsion. However, the interaction force between zircon and quartz was nearly positive, suggesting that the quartz was difficult to adhere to the surface of zircon. In addition, it is observed that the covering capacity of gangue over the zircon was as follows: quartz < goethite < kaolinite < calcite. Compared with Figure 5c, it is concluded that (1) the quartz was difficult to cover over the surface of zircon and rutile; (2) the covering capacity of goethite and kaolinite over the rutile was stronger than that over the zircon; (3) the calcite was prone to adhere to the surface of rutile and zircon.

3.2. EDLVO Theoretical Calculation

3.2.1. Interaction Energy Between the Rutile and Gangue After Adding Surfactants

According to Equation (2), the VW relies on the interparticle distance, the Hamaker constant, and particle size. Without consideration of the effects of addition, the VW′ value was the same as the VW value in the EDLVO theoretical calculations [31]. Therefore, Figure 7a,c,e show the VE′, VH, and VT′ between the rutile and gangue after treatment with the SS, respectively. Figure 7b,d,f show the VE′, VH, and VT′ between the rutile and gangue after treatment with SHMP, respectively.
In Figure 7a,b, all the VE′ between the rutile and gangue after adding reagents were positive, especially for the VE′ between the rutile and calcite, indicating that the electrostatic interaction force caused the particles repel. In Figure 7c,d, all the VH between the rutile and gangue after adding reagents were positive, suggesting that the polar interface interaction force made the particles repel. Generally speaking, the VH between the rutile and gangue after adding SS or SHMP exhibited few differences. According to Figure 7e,f, the VT′ between the rutile and gangue after adding reagents was positive, revealing that the total interaction force made the particles repel. Compared with Figure 5c, the VT′ between the rutile and gangue after adding reagents intensively increased. In addition, either adding the SS or SHMP, the repulsion interaction of rutile with gangue followed the same trend: goethite < calcite < kaolinite < quartz. Moreover, it is found that the SHMP induced stronger repulsion between the rutile and gangue in contrast with the SS, which facilitated the detachment of gangue from the surface of rutile, that is, the addition of SHMP will be more conducive to the subsequent electro-separation purification of rutile.

3.2.2. Interaction Energy Between the Zircon and Gangue After Adding Surfactants

Figure 8a, Figure 8c, and Figure 8e present the VE′, VH, and VT′ between the zircon and gangue after treatment with the SS, respectively. Figure 8b, Figure 8d, and Figure 8f show the VE′, VH, and VT′ between the zircon and gangue after treatment with the SHMP, respectively. Compared with Figure 6b, the VE′ between the zircon and gangue after adding reagents increased, as shown in Figure 8a,b. In addition, it is found that the VH (Figure 8c,d) between the zircon and gangue after adding reagents mainly contributed to the VT′, that is, the fine mud could be well dispersed by introducing the surfactant.
According to Figure 8e,f, the VT′ between the zircon and gangue after adding the SHMP was higher than that after adding the SS, indicating that the dispersion performance of SHMP was superior to the SS. Comparing the rutile with the zircon, the VT′ for the system of zircon and gangue was higher than that for the system of rutile and gangue when the SHMP or SS was added, indicating that the gangue was more prone to detach from the zircon surface.

4. Conclusions

In this paper, the slime was initially investigated by various measurement techniques. Furthermore, mechanisms of fine mud covering over the surface of rutile and zircon were investigated by the DLVO theoretical calculation. The mechanisms of fine mud-enhanced dispersion were further revealed by EDLVO theoretical calculation. Some conclusions were as follows:
(1)
The main gangue in the slime consisted of goethite, quartz, calcite, and kaolinite. In addition, a small amount of rutile and zircon also co-existed. Average particle size of the slime reached 11.06 μm.
(2)
The DLVO theoretical calculations demonstrated that the quartz was difficult to cover over the surface of zircon and rutile, whereas the calcite was prone to adhere to their surface. The covering capacity of goethite and kaolinite over the rutile was stronger than that over the zircon.
(3)
The EDLVO theoretical calculation verified that the addition of SS or SHMP promoted detachment of the gangue from the surface of rutile and zircon. Moreover, the gangue was more prone to detach from the zircon surface in contrast with the rutile. It was also found that the VH between the zircon/rutile and gangue after adding surfactants mainly contributed to the VT′. Comparing the SHMP with the SS, dispersion performance of the former surfactant was superior. These discoveries will provide an excellent theoretical reference for effectively removing fine mud from the surface of rutile ore.

Author Contributions

Conceptualization, Y.W. and Y.Z.; Methodology and calculation, L.R., S.B., L.H. and Y.W.; Software, L.R.; Mechanism investigation and data curation, L.H., S.B. and J.P.; Writing—original draft preparation, Y.W. and J.P.; Review and editing, Y.Z., L.H. and L.R. All authors have read and agreed to the published version of the manuscript.

Funding

This research was supported by the Science and Technology Major Project of Yunnan Province (No. 202202AG050007).

Data Availability Statement

No new data were created or analyzed in this study.

Acknowledgments

Samples are provided by the industrial sponsor Guangxi Ubridge New Material Technology Co., Ltd., Maoming, China.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Srivastava, M.; Jayakumar, V.; Udayan, Y.; SM, M.; Gautam, P.; Nag, A. Additive manufacturing of Titanium alloy for aerospace applications: Insights into the process, microstructure, and mechanical properties. Appl. Mater. Today 2024, 41, 102481. [Google Scholar] [CrossRef]
  2. Karadimas, G.; Salonitis, K. Ceramic matrix composites for aero engine applications—A review. Appl. Sci. 2023, 13, 3017. [Google Scholar] [CrossRef]
  3. Zhu, X.; Geng, Y.; Wu, D.; Houssini, K.; Gao, Z. Evaluating the security of China’s zirconium industry. Resour. Conserv. Recycl. 2023, 199, 107277. [Google Scholar] [CrossRef]
  4. Murty, V.; Upadhyay, R.; Asokan, S. Recovery of zircon from Sattankulam deposit in India-problems and prospects. In The 6th International Heavy Minerals Conference ‘Back to Basics’; The South African Institute of Mining and Metallurgy: Johannesburg, South Africa, 2007; pp. 69–74. [Google Scholar]
  5. Gong, P.; Ren, L.; Bao, S.; Zhang, Y.; Qin, W.; Nguyen, A.V. Flotation separation mechanism of rutile and chlorite using CMC as depressant. Miner. Eng. 2024, 217, 108957. [Google Scholar] [CrossRef]
  6. Liang, Q.-W.; Li, Y.-S.; Sun, Y.-C.; Zhai, D.-G.; Sun, H.-R.; Zhou, S.-X.; Zhang, B.-L.; Lü, X.; Xu, J.-C.; Li, X.-F. Distribution, types, metallogenic regularity and exploration potential analysis of zirconium deposit in China. China Geol. 2025, 8, 408–430. [Google Scholar] [CrossRef]
  7. Zeng, X. The Research of Mining System Scheme of Zr-Ti Placers in Baoding Sea. Master’s Thesis, Central South University, Changsha, China, 2014. [Google Scholar]
  8. Singh, R.; Venkatesh, A.; Sudhakar, C.; Sethy, S.N.; Babu, K.P. Exploration for strategic placer mineral deposits in a fluctuating shoreline: Depositional environment and mineralogical characterization of the NE Odisha coast placers, India. Ore Geol. Rev. 2020, 127, 103850. [Google Scholar] [CrossRef]
  9. Amosah, M.; Yvon, M.; Zhou, J.; Galvin, K. The role of enhanced desliming and gravity separation as a precursor to flotation in the upgrading of cassiterite from tailings. Miner. Eng. 2024, 208, 108581. [Google Scholar] [CrossRef]
  10. Wu, Y.; He, J.; Fan, R.; Wang, Q.; Sun, W.; Ralston, J.; Gao, Z. Effects of surface Chemistry, particle morphology and pretreatment on zircon flotation. Miner. Eng. 2022, 190, 107904. [Google Scholar] [CrossRef]
  11. Nouri, S.; Hoseinian, F.S.; Rezai, B.; Saberyan, K. New pretreatment method for high-tension electrical separation of zircon from quartz. Trans. Nonferrous Met. Soc. China 2019, 29, 1737–1743. [Google Scholar] [CrossRef]
  12. Nzeh, N.S.; Popoola, P.A. Physical beneficiation of heavy minerals–Part 2: A state of the art literature review on magnetic and electrostatic concentration techniques. Heliyon 2024, 10, e32201. [Google Scholar] [CrossRef]
  13. Wang, Z.; Zheng, Y.; Huang, X.; Wang, X.; Peng, J.; Dai, Z. Gravity separation tests of a complex rutile ore. Minerals 2024, 14, 68. [Google Scholar] [CrossRef]
  14. Yu, Y.; Ma, L.; Cao, M.; Liu, Q. Slime coatings in froth flotation: A review. Miner. Eng. 2017, 114, 26–36. [Google Scholar] [CrossRef]
  15. Li, Q.; Huang, L.; Hu, B.; Huang, S.; Zhou, J.; Xu, Y. Synthesis and utilization of a novel amidoxime collector for the flotation separation of cuprite from calcite. Sep. Purif. Technol. 2025, 353, 128447. [Google Scholar] [CrossRef]
  16. Yu, C.; Cai, G.; Hao, S.; Zhao, X.; Luo, X. Fractal characteristics of ore particle crushing under ultrasonic vibration. China Powder Sci. Technol. 2023, 29, 106558. [Google Scholar]
  17. Parsegian, V.A. Van der Waals Forces: A Handbook for Biologists, Chemists, Engineers, and Physicists; Cambridge University Press: Cambridge, UK, 2005. [Google Scholar]
  18. Huang, G.; Pan, Z.; Wang, Y. Dispersion of praseodymium-doped zirconium silicate pigment in aqueous suspension by modified hydroxyl copolymer. Chem. Eng. Res. Des. 2020, 154, 86–100. [Google Scholar] [CrossRef]
  19. Wang, S.; Wang, Y.; Kong, R. New insights into the interaction between low-rank coal particles and clay minerals and its role in flotation responses. Particuology 2024, 94, 48–58. [Google Scholar] [CrossRef]
  20. Wang, C.; Xu, C.; Zhao, S.; Hu, F.; Li, Q. Effect of Organic Matter Removal on Stability of Suspension of Loess Nanoparticles. Acta Pedol. Sin. 2020, 57, 119–129. [Google Scholar]
  21. Xu, D.; Zhu, S.; Zhu, Z.; Cui, H. Influences of sodium hexametaphosphate on interactions of coal and clay particles in flotation. J. Min. Sci. Technol. 2016, 1, 269–276. [Google Scholar]
  22. Wang, Y.; Jiang, W.; Qin, W.; Pan, Z.; Jia, L.; Hong, X.; Song, Z.; Luo, X. The origin of interparticle aggregation: Probing the long-range hydrophobic forces between particles induced by nanobubbles in aqueous solutions. Miner. Eng. 2024, 218, 109030. [Google Scholar] [CrossRef]
  23. Ma, X.; Chen, J.-Y.; Xu, J.-W.; Wu, X.-J.; Chi, H.-D.; Wei, Y.-D. Study on influence factors and mechanism of Floc-Bubble interaction in the flotation treatment of drilling wastewater. Sep. Purif. Technol. 2025, 377, 134300. [Google Scholar] [CrossRef]
  24. Shi, Z.; Ran, B.; Liu, L. Determining the interaction energy of a quartz–kaolinite system at different pH levels by atomic force microscopy and extended DLVO theory. Powder Technol. 2022, 409, 117842. [Google Scholar] [CrossRef]
  25. Gao, N.; Yang, Z.; Teng, Q.; Liu, S. Study on behavior and mechanism of reverse flotation desilication of magnetite enhanced by magnetic amylopectin. Sep. Purif. Technol. 2025, 361, 131286. [Google Scholar] [CrossRef]
  26. Fu, X.; Niu, Z.; Peng, C.; Han, H.; Sun, W.; Yue, T. Quantitative synergistic adsorption affinity of Ca (II) and sodium oleate to predict the surface reactivity of hematite and quartz. Sep. Purif. Technol. 2025, 360, 131196. [Google Scholar] [CrossRef]
  27. Kong, L.; Lv, J.; Li, J.; Ni, L.; Qin, L. The effects of pH regulators on the flotation separation of sphalerite and dolomite and their interaction mechanism. Appl. Surf. Sci. 2025, 680, 161450. [Google Scholar] [CrossRef]
  28. Yan, X.; Wei, L.; Meng, Q.; Wang, J.; Yang, Q.; Zhai, S.; Lu, J. A study on the mechanism of calcium ion in promoting the sedimentation of illite particles. J. Water Process Eng. 2021, 42, 102153. [Google Scholar] [CrossRef]
  29. Chen, Y.; Hu, S.; Li, J.; Weng, L.; Wu, C.; Liu, K. Improvement on combustible matter recovery in coal slime flotation with the addition of sodium silicate. Colloids Surf. A Physicochem. Eng. Asp. 2020, 603, 125220. [Google Scholar] [CrossRef]
  30. Zhou, H.; Xu, L.; Wang, D.; Xue, K.; Tian, J. Selective adsorption mechanism of SHMP onto fine fluorite in bastnaesite flotation system. Colloids Surf. A Physicochem. Eng. Asp. 2023, 670, 131527. [Google Scholar] [CrossRef]
  31. Li, J.; Lv, J.; Kong, L.; Ni, L.; Qin, L. Enhancing flotation separation of fine-grained cassiterite and calcite with cetylpyridine bromide as a dispersant. Adv. Powder Technol. 2024, 35, 104606. [Google Scholar] [CrossRef]
Figure 1. XRD analysis result of the slime.
Figure 1. XRD analysis result of the slime.
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Figure 2. EPMA-mapping analyses results of the slime.
Figure 2. EPMA-mapping analyses results of the slime.
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Figure 3. Particle size analysis of the slime.
Figure 3. Particle size analysis of the slime.
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Figure 4. XRD analyses results of the minerals.
Figure 4. XRD analyses results of the minerals.
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Figure 5. Interaction energy between the rutile and gangue particles: (a) VW; (b) VE; (c) VT.
Figure 5. Interaction energy between the rutile and gangue particles: (a) VW; (b) VE; (c) VT.
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Figure 6. Interaction energy between the zircon and gangue particles: (a) VW; (b) VE; (c) VT.
Figure 6. Interaction energy between the zircon and gangue particles: (a) VW; (b) VE; (c) VT.
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Figure 7. The interaction energy between rutile and gangue particles in the presence of SS and SHMP: VE′ (a,b), VH (c,d), and VT′ (e,f).
Figure 7. The interaction energy between rutile and gangue particles in the presence of SS and SHMP: VE′ (a,b), VH (c,d), and VT′ (e,f).
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Figure 8. The interaction energy between the zircon and gangue particles in the presence of SS and SHMP: VE′ (a,b), VH (c,d), and VT′ (e,f).
Figure 8. The interaction energy between the zircon and gangue particles in the presence of SS and SHMP: VE′ (a,b), VH (c,d), and VT′ (e,f).
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Table 1. XRF analysis of the sample/%.
Table 1. XRF analysis of the sample/%.
ElementsOFeSiAlCaTiZr
Contents48.0018.649.254.344.374.141.83
ElementsMgKPSCeNaCr
Contents0.480.330.280.190.180.120.12
ElementsNdBaMnThZnLaHf
Contents0.110.090.070.0800.070.070.06
ElementsClCuPbYNbSr
Contents0.060.050.040.030.010.01
Table 2. Results of chemical multi-element analysis/%.
Table 2. Results of chemical multi-element analysis/%.
ElementsFeSiAlCaTiZr
Contents16.487.232.633.402.701.78
Table 3. Results of EDS analyses at the corresponding position.
Table 3. Results of EDS analyses at the corresponding position.
PointsOSiFeTiZrAlCaMg
150.0949.91------
253.33-2.7337.23-1.770.31-
350.8521.02--28.10---
448.5226.314.440.99-18.12-0.88
549.2435.423.951.36-7.840.400.41
Table 4. Hamaker constants.
Table 4. Hamaker constants.
MineralsRutile [17]Zircon [18]Quartz [19]Goethite [20]
Hamaker (J)18.1 × 10−208.86 × 10−206.3 × 10−207.8 × 10−20
MineralsKaolinite [21]Calcite [22]Water [23]
Hamaker (J)3.1 × 10−1912.4 × 10−203.7 × 10−20
Table 5. Results of zeta potential measurement (mV).
Table 5. Results of zeta potential measurement (mV).
Zeta PotentialsRutileZirconQuartzGoethiteKaoliniteCalcite
Without reagent−29.6−25.4−42.4−16.3−27.339.84
With SS−43.0−45.6−51.9−24.8−48.1−32.3
With SHMP−52.0−52.6−61.5−27.5−53.6−44.5
Table 6. Results of the contact angle between minerals and water.
Table 6. Results of the contact angle between minerals and water.
Contact Angle (°)RutileZirconQuartzGoethiteKaoliniteCalcite
With SS30.340.122.421.322.838.2
With SHMP30.039.818.820.322.130.2
Table 7. Results of the contact angle between minerals and glycerol.
Table 7. Results of the contact angle between minerals and glycerol.
Contact Angle (°)RutileZirconQuartzGoethiteKaoliniteCalcite
With SS40.651.133.131.034.149.3
With SHMP40.150.130.830.133.241.9
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Wang, Y.; Zheng, Y.; Ren, L.; Bai, S.; Huang, L.; Peng, J. Mechanisms of Fine Mud Covering and Enhanced Dispersion for a Rutile Middling. Metals 2025, 15, 1074. https://doi.org/10.3390/met15101074

AMA Style

Wang Y, Zheng Y, Ren L, Bai S, Huang L, Peng J. Mechanisms of Fine Mud Covering and Enhanced Dispersion for a Rutile Middling. Metals. 2025; 15(10):1074. https://doi.org/10.3390/met15101074

Chicago/Turabian Style

Wang, Yang, Yongxing Zheng, Liuyi Ren, Shaojun Bai, Lingyun Huang, and Jieli Peng. 2025. "Mechanisms of Fine Mud Covering and Enhanced Dispersion for a Rutile Middling" Metals 15, no. 10: 1074. https://doi.org/10.3390/met15101074

APA Style

Wang, Y., Zheng, Y., Ren, L., Bai, S., Huang, L., & Peng, J. (2025). Mechanisms of Fine Mud Covering and Enhanced Dispersion for a Rutile Middling. Metals, 15(10), 1074. https://doi.org/10.3390/met15101074

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