Next Article in Journal
Overprinted Metamorphic Assemblages in High-Alumina Metapelitic Rocks in Contact with Varnous Pluton (NNW Greece)
Previous Article in Journal
Separation of Rare Earth Elements by Ion Exchange Resin: pH Effect and the Use of Fractionation Column
Previous Article in Special Issue
Pyrite–Coal Depressants Interactions During Coal Reverse Flotation
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Minerals
Volume 15
Issue 8
10.3390/min15080822
minerals-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Harnessing Mixed Fatty Acid Synergy for Selective Flotation of Apatite from Calcite and Quartz with Sodium Alginate

by
Imane Aarab
1,*,
Khalid El Amari
2,
Abdelrani Yaacoubi
3,
Abdelaziz Baçaoui
3 and
Abderahman Etahiri
4
1
Laboratory of Mining, Metallurgy & Materials Engineering, Department of Chemical Engineering & Energy, Rabat National School of Mines, Hadj Ahmed Cherkaoui Avenue, Agdal, P.O. Box 753, Rabat 10100, Morocco
2
Laboratory of Georessources, Geoenvironment & Civil Engineering, Department of Earth Sciences, Faculty of Sciences and Technologies of Marrakesh (FSTM), Cadi Ayyad University, Boulevard Abdelkrim Al Khattabi, P.O. Box 549, Marrakesh 40000, Morocco
3
Laboratory of Applied Chemistry and Biomass, Department of Chemistry & Development, Faculty of Sciences Semlalia-Marrakesh (FSSM), Cadi Ayyad University, Boulevard Prince My Abdellah, P.O. Box 2390, Marrakesh 40000, Morocco
4
Laboratory of Analysis of Geological Materials, Department of Geology and Sustainable Mining, Mohammed VI Polytechnic University, Lot 660, Hay Moulay Rachid, BenGuerir 43150, Morocco
*
Author to whom correspondence should be addressed.
Minerals 2025, 15(8), 822; https://doi.org/10.3390/min15080822
Submission received: 4 July 2025 / Revised: 22 July 2025 / Accepted: 29 July 2025 / Published: 1 August 2025
(This article belongs to the Special Issue Surface Chemistry and Reagents in Flotation)
Browse Figures
Versions Notes

Abstract

Maximizing the efficient utilization of critical apatite resources through flotation necessitates the exploration of effective and innovative collectors. This study investigates the potential of a fatty acid mixture (FAM) synthesized from saturated palmitic and stearic acids, monounsaturated oleic and palmitoleic acids, and polyunsaturated linoleic acid. The saponified collector FAM and the depressant sodium alginate (NaAl) achieved a direct flotation of apatite from calcite and quartz (97% apatite, 10% calcite, and 7% quartz). The flotation performance with the tested combination exhibited a highly effective enrichment of apatite, mainly from calcite, which aligns with the surface chemistry assessments. Adsorption tests and zeta potential measurements confirmed the micro-flotation results. They provided compelling evidence of a chemisorption interaction between Ca2+ sites on calcite and the carboxyl and hydroxyl groups of NaAl. FTIR analyses suggested a reaction between the apatite surface and the carboxyl groups of saturated and unsaturated acid groups in FAM, even those conditioned with NaAl before, facilitating the complex formation. Remarkably, the synergistic effect of the functional groups demonstrates dual functionality, serving as both a hydrophilic entity for calcite and a hydrophobic entity for apatite flotation. The universal mechanism unveils substantial potential for the extensive application of FAM within apatite flotation.

1. Introduction

Phosphate ores, which are crucial for producing phosphate fertilizers, are commonly enriched through flotation to maintain food production sustainability [1,2]. As high-grade phosphate reserves continue to decline, there is growing interest in mining and processing low-grade phosphate to meet the rising demand for fertilizers driven by the increasing population [3,4,5,6]. The main components of most sedimentary phosphate ores are calcium minerals, namely apatite, carbonates, and silicates. The selective separation of these minerals is challenging due to their similar surface properties [7,8,9]. Single fatty acids are the commonly used collectors in calcium mineral flotation. However, their effectiveness and selectivity toward specific minerals depend on numerous factors, such as the length of their hydrocarbon chain, degree of unsaturation, and the polar and nonpolar functional groups they contain [10,11,12,13,14,15,16].
Industrial practices and laboratory investigations have shown that a suitable flotation strategy for upgrading a specific phosphate ore may not be so for another. Variations in mineralogical composition and P2O5 content insufficiently explain the different flotation responses of phosphate ores from diverse origins. Several research works have outlined the intrinsic characteristics of the minerals that compose the ore and their interactions with the reagents, such as the chemical heterogeneity, surface texture, crystallinity, and degree of dissolution [17].
Substantial effort has been made in recent decades to tackle the complexity of this particular grade using various technologies and methods [18,19,20,21,22,23,24]. However, their sensitivity to the operating conditions and their limitations due to industrial constraints render them less efficient and not scalable, leading to the prominence of froth flotation as an effective and economical beneficiation technique for apatite recovery.
In the wake of the absence of universal guidelines for the flotation of low-grade phosphate ores, various strategies can be followed, including direct, reverse, or stepwise flotation, also known as the double float process [25,26,27,28,29,30]. It is important to note that the choice of flotation strategy depends on the behavior of the phosphate with respect to the reagents used [31,32]. Direct flotation is suitable for phosphate ores with low apatite grade and high gangue mineral content, as it reduces the consumption of collectors. As a result, it has gained significant attention in recent decades.
The mining industry has dedicated significant efforts to developing potent collectors for apatite and depressants for carbonates in direct flotation processes. Several surfactants, such as sodium oleate [33,34], oleic acid [35,36], linoleic acid [37,38], and hydroxamic acid [39,40], have been used in industrial processes. However, limitations persist regarding selectivity, thus hindering their widespread industrial use unless combined with selective depressants. Single fatty acids grapple with affinity issues toward valuable and accessory minerals, imperiling their selectivity. To address these concerns, researchers have focused on creating more robust collectors. One notable approach involves the design of mixed fatty acids, which has proven essential in improving overall flotation performance, addressing selectivity, adsorption compactness, and excessive consumption [41]. Novel surfactants with multifunctional groups demonstrate the industry’s commitment to constant improvement and offer promising solutions to existing challenges in phosphate flotation.
The performance of mixed collector systems relies on the properties of the reagents, the interaction between the collector and the particles, as well as the ratio and structure of the reagents [42]. Research on combinations of collectors has shown that their synergistic effects offer benefits such as lower reagent dosage, enhanced grade/recovery, increased coverage of mineral surfaces, improved contact angle, and mitigation of the deleterious effect of Ca2+ ions, which cause the collector to precipitate [43,44,45,46,47].
Using mixed collectors in optimal conditions combines the advantages of individual collectors and meets multifaceted requirements [48,49]. For instance, Cao et al. found that a mixture containing 54% oleic acid, 36% linoleic acid, and 10% linolenic acid demonstrated stronger collecting power for apatite than using oleic acid alone. FTIR analyses confirmed improved chemisorption involving the carboxyl groups of each fatty acid and calcium species at the apatite surface [37]. Karlkvist et al. demonstrated the effectiveness of the dicarboxylic collector C12MalNa2 in efficiently floating apatite in the complex apatite/calcite system, despite both minerals having similar types of adsorption sites on their surfaces [50]. Santos et al. discovered that the mixed composition in oil-based Amazonian collectors, mainly composed of oleate and palmitate, affected the critical micelle concentration (CMC), adsorption density, and selective conditions for separating apatite and carbonate minerals [51]. El-Midany and Arafat investigated the reverse apatite flotation using a mixture of oleic acid and sodium dodecyl sulfate at a 1:1 mixing ratio and a pH of 6. A concentrate grade of up to 33% P2O5 with a recovery of 85% at a lower collector dosage was achieved [52]. Filippova et al. highlighted the synergistic effect of combining the anionic reagent D2EHPA (di-2-ethylhexylphosphoric acid) with a nonionic reagent, which was particularly effective in shielding the ionic head groups by reducing the electrostatic repulsion and hydrophobic chain interactions [53]. Farid et al. explored a mixture of soybean and sunflower oil as a collector for the reverse flotation of the apatite/calcite system. A product with 29.57% P2O5 and a recovery rate of 98.82% at a pH of 4 was obtained [54]. However, very few studies have focused on the direct flotation of apatite using mixed collectors, even though choosing the right collector combination is crucial for improving flotation efficiency and reducing costs.
As part of an ongoing research project focused on developing efficient collectors for phosphate mineral flotation, the present work assesses the synergistic effect of the collector FAM featuring saturated and unsaturated fatty acids in the adsorption and recovery of calcium minerals. Micro-flotation experiments were further consolidated with zeta potential measurements, adsorption tests, and FTIR spectra analyses to scrutinize its performance.

2. Materials and Methods

2.1. Materials

2.1.1. Pure Mineral Specimens

Pure mineral specimens of fluorapatite (98.34%), calcite (99.03%), and quartz (99.28%), based on the mineralogy of the phosphate ore to be beneficiated, were collected from localities in Morocco. XRD characterization (Figure 1) and XRF analysis (Table 1) double-checked the purity of the pebbles. The measurements were conducted using a PANalytical X’PERT3 Powder diffractometer (Malvern PANalytical, Malvern, Worcestershire, UK) and a PANalytical AxiosMAX sequential spectrometer (Malvern PANalytical, Malvern, Worcestershire, UK), respectively. The specimens were hand-sorted, crushed, then ground with an agate mortar to produce two-size fractions. The [−160 + 125 µm] fraction was intended for micro-flotation tests, whereas the sub-40 µm fraction was reserved for zeta potential measurements, adsorption tests, and FTIR analyses.

2.1.2. Chemical Reagents

The study used reagents purchased from Sigma Aldrich, except for the fatty acids from VWR Chemicals. Table 2 discloses the details. FAM encompasses the fatty acids in the mixing ratio listed in Table 3. The collector’s performance in phosphate ore flotation improves with a predominant concentration of oleic acid over linoleic acid [55].
To synthesize FAM, the fatty acids were mixed with 95% ethanol and NaOH in a 250 mL round-bottom flask and agitated for 2 h under reflux heating at a temperature of 65 °C. Afterward, the crude collector was transferred into a beaker containing a saturated sodium chloride solution, resulting in a layer of soap precipitate floating on the surface of the salted water. The product was then vacuum filtered, washed with distilled water, and dried in a vacuum drying oven at 40 °C for 72 h, resulting in the corresponding collector FAM.

2.2. Experimental Methods

2.2.1. Micro-Flotation Tests

Micro-flotation tests were conducted in a 325 mL Hallimond tube fitted with a sintered glass of porosity three and a magnetic stirrer, using 1 g of pure mineral [−180 + 125 µm], 100 mL of deionized water, and NaOH to adjust the pH. Deionized water was used to provide a chemically stable and controlled medium, free from interfering ionic species that may affect reagent–mineral interactions. The pulp was conditioned with reagents for 3 min each, poured into the Hallimond tube, and nitrogen flowed at 100 mL/min rate, with the micro-flotation test lasting 1 min. The froth products were collected, filtered, dried, and weighed to calculate the recovery rate. Experiments were carried out in triplicate to ensure accuracy and reliability. The average value was the final result, and the error bars display the standard deviation.

2.2.2. Zeta Potential Measurements

The Zeta potential of pure minerals was measured using a Zetasizer Nano ZS (Malvern PANalytical, Malvern, Worcestershire, UK) at room temperature. In so doing, 0.1 g of the sub-40 μm pure mineral fraction was suspended in 50 mL of a 1.0 mM NaCl background electrolyte. The pulp pH was adjusted using HCl/NaOH solutions and then conditioned with reagents at a specific dosage and conditioning time, according to the micro-flotation procedure. After 30 min of settling, 1 mL of the supernatant was derived for measurement. The reported value was the average of three repetitions, and the error bars displayed the standard deviation.

2.2.3. Adsorption Tests

The adsorption of reagents was quantified via the colorimetric method using HITACHI U-3900H spectrophotometer (Hitachi High-Tech Corporation, Tokyo, Japan). The amount of the residual mixed collector in the supernatant was determined through the Gregory method [56] at a wavelength of 435 nm. On the other hand, the Dubois method [57] was called upon to measure the adsorption of organic depressant NaAl at a wavelength of 490 nm.
To conduct adsorption tests, 0.5 g of a pure mineral fraction with a particle size of less than 40 μm was suspended in 50 mL of reagent solution. After pH adjustment, the mixture was stirred for 5 min at room temperature. The supernatant was obtained through solid–liquid separation via centrifugation at 5000 rpm for 5 min.
The specific surface areas of fluorapatite, calcite, and quartz were 6.75 m2/g, 1.97 m2/g, and 2.43 m2/g, respectively, determined by the BET N2 adsorption method using 3Flex 3500 Micrometric (Micromeritics Instrument Corporation, Norcross, GA, USA).

2.2.4. FTIR Spectra Analyses

FTIR spectroscopy was performed using IR VERTEX 70 (Bruker Optics GmbH, Bremen, Germany) to study FAM adsorption onto the mineral surfaces. For this purpose, 0.15 g of sub-40 µm pure mineral underwent the same procedure described in the micro-flotation section. The solid fraction was filtered, gently washed with deionized water, and dried at 80 °C for 24 h. An amount of 1 mg of mineral powder was mixed with 99 mg of KBr and pressed into a thin plate for analysis. The samples were analyzed in transmittance mode within the 4000–400 cm−1 wavenumber range. For each sample, 32 scans were conducted at a 2 cm−1 resolution.

3. Results and Discussion

3.1. Single Mineral Flotation

The floatability of apatite, calcite, and quartz was first assessed through micro-flotation tests in the FAM system without depressants at an alkaline pH. Figure 2 shows that pure mineral recoveries increase with increasing FAM concentration, with the apatite recovery reaching the maximum at a concentration of 80 mg/L. Apatite and calcite follow the same pattern, with a slight difference in favor of apatite. Quartz recovery remains well below that of apatite and calcite. Therefore, FAM alone is insufficiently effective to separate apatite and calcite.
Figure 3 displays the effect of pH and reagents on apatite, calcite, and quartz floatability. Both apatite and calcite exhibit notable floatability with a recovery of over 80% at an alkaline pH in the absence of NaAl, which is consistent with the results of previous studies [58,59]. However, when conditioned with NaAl before FAM, the apatite and calcite flotation patterns exhibit significant differences. In the presence of NaAl, calcite recovery gradually decreases with increasing pH until it reaches approximately 10% at a pH of 11. Nonetheless, NaAl barely affected the apatite recovery, which remained up 96%. As for quartz, neither FAM nor NaAl affected its floatability. The differences in the flotation performance of pure minerals make NaAl/FAM an effective combination for separating mainly calcite from apatite at a pH of approximately 11.
The effect of NaAl concentration on pure mineral floatability was investigated at a pH of 11 and 80 mg/L FAM. Figure 4 depicts the findings. As the NaAl concentration rises from 0 to 35 mg/L, calcite recovery declines from 90% to 10%, while apatite recovery remains stable at approximately 97%. Meanwhile, quartz recovery slightly dropped from 9% to 7%. An amount of 30 mg/L of NaAl was optimal to achieve the maximum difference in apatite and calcite recovery. Based on flotation recovery rates of pure minerals under different reagent schemes, a pH of 11, NaAl 30 mg/L (equivalent to ~ 3.0 Kg/t), and FAM 80 mg/L ( ~ 8.0 Kg/t) were identified as optimal conditions for single-mineral flotation tests.
Compared to a previously reported system employing sodium oleate (NaOl) in combination with NaAl as a depressant [58], the current NaAl + FAM scheme demonstrates enhanced reagent efficiency, improved selectivity, and greater cost-effectiveness. Specifically, the required depressant dosage was reduced by approximately 25%, while the recovery of calcite was more effectively suppressed, dropping to around 10%, in contrast to 39% under the NaOl-based formulation. Importantly, apatite recovery remained consistently high at approximately 97%. These results reflect the superior synergistic interaction between NaAl and FAM, and they highlight the potential of this reagent combination as a cost-effective and selective alternative formulation for the flotation of carbonate-rich phosphate ores.
The fundamental mechanism underlying NaAl/FAM flotation selectivity is delved into in the subsequent sections, providing a comprehensive understanding of the surfactants’ effectiveness in the complex apatite/calcite/quartz mineral system.

3.2. Adsorption Behavior and Mechanistic Insights

The adsorption performance was investigated at a pH of 11, NaAl 30 mg/L, and FAM 80 mg/L. Figure 5 shows the adsorption characteristics of minerals and reagents. FAM proved a higher affinity toward calcite (2.853 mg/m2) than apatite (0.522 mg/m2), whereas the adsorption of FAM on quartz (0.083 mg/m2) was far lower than on the two minerals. These findings comply with previous studies and micro-flotation results [58,60], which ascribed this adsorption order to the calcium density at the mineral surface (calcite (8.2 μmol·m−2) > apatite (5.1–6.6 μmol·m−2) as well as the solubility product of minerals: calcite (4.6 × 10−9) > apatite (6.3 × 10−126) [24,33,61]. Moreover, the synergistic effect of fatty acids composing FAM on the adsorption enhancement was patent. The quantity of reagents adsorbed onto the minerals’ surfaces noticeably increased compared to NaOl [58]. Although conditioned with NaAl, FAM adsorbed onto the apatite surface, which managed to float. The observed phenomenon can be explained by the fact that saturated and unsaturated acids adsorb tightly to apatite due to their compact nature and stable affinity.
Furthermore, the NaAl treatment before FAM had minimal effect on the amount of reagents adsorbed onto apatite and quartz. However, FAM adsorption onto the calcite surface decreased significantly from 2.853 mg/m2 to only 1.115 mg/m2. This result further highlights the effectiveness of NaAl as a depressant of calcite, attributed to the chelating mechanism and bulky structure leading to steric hindrance, thus hampering FAM adsorption on Ca2+ [58,59,62].

3.3. Zeta Potential and Surface Charge Behavior

To further clarify the adsorption characteristics, the zeta potentials of pure apatite, calcite, and quartz minerals treated with flotation reagents at different pH values were measured. Figure 6 indicates that the isoelectric points (IEPs) for untreated apatite, calcite, and quartz were 3, 3.5, and 3.4, respectively. These findings are consistent with reported values in the previous studies [47,58,63].
A significant decrease in the zeta potential of pure minerals with increasing pH over the investigated pH range was apparent.
When exposed to NaAl alone, both apatite and calcite exhibited negative shifts. At a pH of 11, the zeta potential of apatite shifted from −25.12 mV to −52.25 mV, while the zeta potential of calcite dropped from −14.8 mV to −37.16 mV. The degree of change in the zeta potential is quasi-comparable for both minerals, as it is slightly superior for apatite, suggesting that the carboxylate species on NaAl were attracted to and adsorbed onto the Ca2+ sites of both minerals.
Similarly, when conditioned with FAM, the intense interaction of the carboxylate and calcium species dissolved from saturated and unsaturated fatty acids of FAM with the calcium sites led to considerable changes in the zeta potentials of apatite and calcite in the negative direction. At a pH of 11, the zeta potentials of apatite (Figure 6a) and calcite (Figure 6b) shifted to −65.03 mV and −52.74 mV, respectively, after treatment with FAM alone. Apatite exhibited a more pronounced negative shift in the zeta potential than calcite.
However, when NaAl and FAM were added, apatite and calcite showed different zeta potential shift trends. Sequentially adding NaAl and FAM to calcite slurry results in similar surface zeta potentials of calcite as adding NaAl alone, indicating that NaAl pre-adsorption on calcite surface hinders subsequent FAM adsorption. In contrast, the zeta potential of apatite further negatively shifted to −62.94 mV upon the sequential addition of NaAl and FAM. These results imply that NaAl exhibits weaker interactions with apatite than calcite, and FAM still can firmly adsorb onto the surface of apatite in the presence of NaAl. The compact and tight adsorption of FAM on the apatite surface can be attributed to a combination of electrostatic shielding between functional groups and the variation in fatty acid chain lengths (C16–C18), which include both saturated and unsaturated components. The presence of heterogeneous chain lengths is known to promote synergistic interactions among the molecules, facilitating closer packing and reducing steric hindrance. As reported in the previous studies [29,51,64,65], this variation enhances the balance between molecular mobility and hydrophobic coverage, thereby increasing the stability and compactness of the adsorption layer. In this context, the synergistic effect of the mixed fatty acids contributes to a more uniform and effective surface coverage, improving the collector’s performance.
Concerning quartz (Figure 6c), either untreated or treated with reagents, the zeta potential had barely shifted, inferring that NaAl and FAM had little effect on the quartz surface [47].
Consistent zeta potential measurements with the adsorption tests and micro-flotation results motivated the FTIR spectra analyses.

3.4. FTIR Interpretation of Reagent-Surface Interactions

FTIR spectroscopy was conducted to investigate the functional groups involved in the adsorption of the NaAl and FAM reagent system on the surfaces of apatite, calcite, and quartz. The analysis aimed to elucidate the chemical interactions underlying the selective adsorption behavior observed in micro-flotation tests. Figure 7 presents the FTIR spectra of each mineral before and after conditioning with FAM and the NaAl + FAM combination.
For apatite (Figure 7a), the spectral region between 3600 and 2700 cm−1, associated with methyl and methylene stretching vibrations of the hydrocarbon chains, displayed distinct peaks at 2988.02 cm−1 and 2878.23 cm−1, corresponding to the asymmetric stretching of CH3 and symmetric stretching of CH2, respectively [66,67,68]. In the region between 1750 and 1400 cm−1, attributed to the carboxylate group, several meaningful shifts were observed. The band at 1629.25 cm−1 shifted to 1635.05 cm−1 after FAM conditioning and shifted slightly back to 1631.18 cm−1 following NaAl + FAM treatment, indicating changes in the asymmetric stretching vibration of the v a s (COO−) group. Similarly, the peak at 1401.73 cm−1, associated with =C–H (cis) bending, shifted to 1384.09 cm−1 after FAM adsorption [69]. The following pronounced shift was also observed in the phosphate region: the P–O asymmetric stretching peak initially at 1042.41 cm−1 moved to 1036.62 cm−1 after FAM treatment and nearly returned to 1042.36 cm−1 after NaAl + FAM conditioning. Minor changes in the P–O bending vibration were also noted, with a shift from 569.46 cm−1 to 567.53 cm−1 with FAM and to 570.03 cm−1 with NaAl + FAM. These spectral variations suggest strong interactions between FAM and phosphate groups, while the minimal differences following NaAl + FAM treatment indicate that sodium alginate does not impede the adsorption of FAM onto apatite surfaces. These observations align well with the adsorption data.
For calcite (Figure 7b), characteristic carbonate bands appeared at 1802.99 cm−1 and 1428.49 cm−1 due to the stretching vibrations of the CO32− group and at 878.33 cm−1 and 706.52 cm−1 due to its deformation vibrations [70]. After FAM treatment, CH2 stretching bands at 2976.67 cm−1 and 2870.50 cm−1 became apparent, indicative of the hydrocarbon tail of the collector. The asymmetric –COO– band at 1428.49 cm−1 broadened and shifted to 1457.45 cm−1, confirming the chemisorption of FAM functional groups on the calcite surface. Upon NaAl + FAM conditioning, the carbonate stretching band at 1802.99 cm−1 shifted to 1799.13 cm−1, while the 1428.49 cm−1 band moved to 1418.84 cm−1 and broadened significantly, reflecting further adsorption of NaAl. These changes suggest a competitive interaction, whereby NaAl adsorbs preferentially or additionally on the calcite surface, reducing FAM coverage. This is consistent with the reduced floatability of calcite observed in flotation experiments.
In the case of quartz (Figure 7c), characteristic silicate vibrations were observed at 465.22 cm−1 (Si–O–Si stretching), 690.74 cm−1 (symmetric Si–O bending), 787.74 cm−1 (Si–O symmetric stretching), and 1084.88 cm−1 (Si–O stretching). After treatment with FAM and NaAl + FAM, these bands exhibited only minor shifts to 471.02, 681.16, 783.74, and 1082.95 cm−1, respectively, indicating negligible interactions between the reagents and the quartz surface [58]. The weak response of quartz to the reagent system further supports its passive behavior in the flotation process.
Overall, the FTIR spectral shifts observed for apatite and calcite, contrasted with the limited spectral changes for quartz, reinforce the selectivity of the NaAl + FAM reagent system. These findings, when considered alongside micro-flotation, zeta potential, and adsorption study results, provide consistent evidence of the mineral-specific interactions governing the adsorption mechanisms and flotation behavior.

4. Conclusions

This study demonstrates the potential of a novel reagent scheme based on a mixed fatty acid collector (FAM) combined with sodium alginate (NaAl) as a selective depressant for the efficient separation of apatite from calcite and quartz. The synergistic interaction of the fatty acid mixture, mainly composed of oleic acid and minor proportions of linoleic, palmitic, stearic, and palmitoleic acids, was systematically investigated through micro-flotation experiments, adsorption studies, zeta potential measurements, and FTIR spectroscopy. The principal findings are as follows:
Micro-flotation experiments confirmed that the NaAl + FAM combination successfully achieved the direct flotation of apatite from calcite and quartz, with a 97% apatite recovery, a 10% calcite recovery, and a 7% quartz recovery at an optimal alkaline pH of 11.
  • Adsorption tests indicated that NaAl efficiently depresses calcite and quartz without interfering with FAM adsorption on apatite surfaces, ensuring mineral-specific separation.
  • Zeta potential measurements revealed a shift toward more negative values after conditioning with NaAl/FAM. The overlapping trends between (i) NaAl and NaAl + FAM curves for calcite and (ii) FAM and NaAl + FAM curves for apatite highlighted distinct adsorption behaviors, supporting the system’s selectivity.
  • FTIR spectral analysis identified characteristic functional groups involved in collector and depressant interactions, further validating the proposed adsorption mechanism and surface affinities.
  • The NaAl + FAM system demonstrated a high flotation selectivity with minimal depressant consumption, achieving effective calcite depression while maintaining high apatite recovery and minimal quartz flotation. This underlines the system’s technical efficiency and economic advantage in processing carbonate-rich phosphate ores.

Author Contributions

Conceptualization, I.A. and K.E.A.; Methodology, I.A. and K.E.A.; Software, I.A.; Validation, K.E.A., A.Y. and A.E.; Formal analysis, I.A. and K.E.A.; Investigation, I.A.; Resources, A.E.; Data curation, A.Y.; Writing—original draft, I.A.; Writing—review & editing, K.E.A., A.Y., A.B. and A.E.; Visualization, I.A.; Supervision, I.A. and K.E.A.; Project administration, A.B.; Funding acquisition, A.B. All authors have read and agreed to the published version of the manuscript.

Funding

The authors gratefully acknowledge the financial support of the R&D Initiative—Call for projects around phosphates APPHOS—sponsored by OCP Foundation, R&D OCP, Mohammed VI Polytechnic University, National Center of Scientific and Technical Research CNRST, and Ministry of Higher Education, Scientific Research, and Professional Training of Morocco MESRSFC, grant number: TRT-BAC-01/2017.

Data Availability Statement

Data are contained within the article.

Conflicts of Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

References

  1. Manoukian, L.; Metson, G.; Hernández, E.M.; Vaneeckhaute, C.; Frigon, D.; Omelon, S. Forging a Cohesive Path: Integrating Life Cycle Assessments of Primary-Origin Phosphorus Fertilizer Production and Secondary-Origin Recovery from Municipal Wastewater. Resour. Conserv. Recycl. 2023, 199, 107260. [Google Scholar] [CrossRef]
  2. Zhang, J.; Yu, K.; Yu, M.; Dong, X.; Sarwar, M.T.; Yang, H. Facet-Engineering Strategy of Phosphogypsum for Production of Mineral Slow-Release Fertilizers with Efficient Nutrient Fixation and Delivery. Waste Manag. 2024, 182, 259–270. [Google Scholar] [CrossRef]
  3. Bai, Z.; Liu, L.; Kroeze, C.; Strokal, M.; Chen, X.; Yuan, Z.; Ma, L. Optimizing Phosphorus Fertilizer Use to Enhance Water Quality, Food Security and Social Equality. Resour. Conserv. Recycl. 2024, 203, 107400. [Google Scholar] [CrossRef]
  4. Wu, Z.; Feng, X.; Zhang, Y.; Fan, S. Repositioning Fertilizer Manufacturing Subsidies for Improving Food Security and Reducing Greenhouse Gas Emissions in China. J. Integr. Agric. 2024, 23, 430–443. [Google Scholar] [CrossRef]
  5. Kurniawan, T.A.; Othman, M.H.D.; Liang, X.; Goh, H.H.; Chew, K.W. From Liquid Waste to Mineral Fertilizer: Recovery, Recycle and Reuse of High-Value Macro-Nutrients from Landfill Leachate to Contribute to Circular Economy, Food Security, and Carbon Neutrality. Process Saf. Environ. Prot. 2023, 170, 791–807. [Google Scholar] [CrossRef]
  6. Zhu, G.; Sun, Y.; Shakoor, N.; Zhao, W.; Wang, Q.; Wang, Q.; Imran, A.; Li, M.; Li, Y.; Jiang, Y.; et al. Phosphorus-Based Nanomaterials as a Potential Phosphate Fertilizer for Sustainable Agricultural Development. Plant Physiol. Biochem. 2023, 205, 108172. [Google Scholar] [CrossRef] [PubMed]
  7. Ruan, Y.; He, D.; Chi, R. Review on Beneficiation Techniques and Reagents Used for Phosphate Ores. Minerals 2019, 9, 253. [Google Scholar] [CrossRef]
  8. Sajid, M.; Bary, G.; Asim, M.; Ahmad, R.; Ahamad, M.I.; Alotaibi, H.; Rehman, A.; Khan, I.; Guoliang, Y. Synoptic View on P Ore Beneficiation Techniques. Alex. Eng. J. 2022, 61, 3069–3092. [Google Scholar] [CrossRef]
  9. Lamghari, K.; Taha, Y.; Ait-Khouia, Y.; Elghali, A.; Hakkou, R.; Benzaazoua, M. Sustainable Phosphate Mining: Enhancing Efficiency in Mining and Pre-Beneficiation Processes. J. Environ. Manag. 2024, 358, 120833. [Google Scholar] [CrossRef]
  10. Zeng, L.; Ding, K.; Zhang, X.; Zhou, Y.; Han, H. New Insights into the Influence of Mineral Surface Transformation on the Flotation Behavior of Anhydrite/Apatite. Colloids Surf. A Physicochem. Eng. Asp. 2024, 685, 133215. [Google Scholar] [CrossRef]
  11. Gomez-Flores, A.; Heyes, G.W.; Ilyas, S.; Kim, H. Prediction of Grade and Recovery in Flotation from Physicochemical and Operational Aspects Using Machine Learning Models. Miner. Eng. 2022, 183, 107627. [Google Scholar] [CrossRef]
  12. Faramarzpour, A.; Yazdi, M.S.; Mohammadi, B.; Chelgani, S.C. Calcite in Froth Flotation—A Review. J. Mater. Res. Technol. 2022, 19, 1231–1241. [Google Scholar] [CrossRef]
  13. Huang, H.; Gao, W.; Li, X. Effect of SO42- and PO43- on Flotation and Surface Adsorption of Dolomite: Experimental and Molecular Dynamics Simulation Studies. Colloids Surf. A Physicochem. Eng. Asp. 2024, 680, 132699. [Google Scholar] [CrossRef]
  14. Han, H.; Peng, M.; Nguyen, A.V.; Hu, Y.; Sun, W.; Wei, Z. The Interfacial Water Structure at Mineral Surfaces. In Encyclopedia of Solid-Liquid Interfaces, 1st ed.; Wandelt, K., Bussetti, G., Eds.; Elsevier: Oxford, UK, 2024; pp. 552–566. [Google Scholar] [CrossRef]
  15. Molaei, N.; Forster, J.; Shoaib, M.; Wani, O.; Khan, S.; Bobicki, E. Efficacy of Sustainable Polymers to Mitigate the Negative Effects of Anisotropic Clay Minerals in Flotation and Dewatering Operations. Clean. Eng. Technol. 2022, 8, 100470. [Google Scholar] [CrossRef]
  16. Feng, B.; Zhang, L.; Zhang, W.; Wang, H.; Gao, Z. Mechanism of Calcium Lignosulfonate in Apatite and Dolomite Flotation System. Int. J. Miner. Metall. Mater. 2022, 29, 1697–1704. [Google Scholar] [CrossRef]
  17. Li, H.; Chen, Y.; Zheng, H.; Huang, P.; Yang, P.; Chen, Q.; Weng, X.; He, D.; Song, S. Effect of Geological Origin of Apatite on Reverse Flotation Separation of Phosphate Ores Using Phosphoric Acid as Depressant. Miner. Eng. 2021, 172, 107182. [Google Scholar] [CrossRef]
  18. Boucif, R.; Filippov, L.O.; Maza, M.; Benabdeslam, N.; Foucaud, Y.; Marin, J.; Korbel, C.; Demeusy, B.; Diot, F.; Bouzidi, N. Optimizing Liberation of Phosphate Ore through High Voltage Pulse Fragmentation. Powder Technol. 2024, 437, 119549. [Google Scholar] [CrossRef]
  19. He, J.; Huang, S.; Chen, H.; Zhu, L.; Guo, C.; He, X.; Yang, B. Recent Advances in the Intensification of Triboelectric Separation and Its Application in Resource Recovery: A Review. Chem. Eng. Process.-Process Intensif. 2023, 185, 109308. [Google Scholar] [CrossRef]
  20. Hassanzadeh, A.; Safari, M.; Hoang, D.H.; Khoshdast, H.; Albijanic, B.; Kowalczuk, P.B. Technological Assessments on Recent Developments in Fine and Coarse Particle Flotation Systems. Miner. Eng. 2022, 180, 107509. [Google Scholar] [CrossRef]
  21. Lv, X.; Xiang, L.; Wang, T. Intensification of Low-Grade Phosphate Ore Purification Using a Hydrocyclone with Venturi-Style Inlet. J. Ind. Eng. Chem. 2024, 135, 257–269. [Google Scholar] [CrossRef]
  22. Tang, H.; Deng, Z.; Tang, Y.; Tong, X.; Wei, Z. Hotspots and Trends of Sphalerite Flotation: Bibliometric Analysis. Sep. Purif. Technol. 2023, 312, 123316. [Google Scholar] [CrossRef]
  23. Han, J.; Chen, P.; Liu, T.; Li, Y. Research and Application of Fluidized Flotation Units: A Review. J. Ind. Eng. Chem. 2023, 126, 50–68. [Google Scholar] [CrossRef]
  24. Filippov, L.O.; Filippova, I.V.; Fekry, A.M. Evaluation of Interaction Mechanism for Calcite and Fluorapatite with Phosphoric Acid Using Electrochemical Impedance Spectroscopy. J. Mater. Res. Technol. 2024, 29, 2316–2325. [Google Scholar] [CrossRef]
  25. Zhang, W.; Ren, Q.; Tu, R.; Liu, S.; Qiu, F.; Guo, Z.; Liu, P.; Xu, S.; Sun, W.; Tian, M. The Application of a Novel Amine Collector, 1-(Dodecylamino)-2-Propanol, in the Reverse Flotation Separation of Apatite and Quartz. J. Mol. Liq. 2024, 399, 124377. [Google Scholar] [CrossRef]
  26. Lan, S.; Dong, L.; Shen, P.; Zheng, Q.; Qiao, L.; Liu, D. Synergistic Impact of Surfactant and Sodium Oleate on Dolomite Removal from Fluorapatite via Reverse Flotation. Appl. Surf. Sci. 2024, 655, 159504. [Google Scholar] [CrossRef]
  27. Wei, Z.; Zhang, Q.; Wang, X. New Insights on Depressive Mechanism of Citric Acid in the Selective Flotation of Dolomite from Apatite. Colloids Surf. A Physicochem. Eng. Asp. 2022, 653, 130075. [Google Scholar] [CrossRef]
  28. Huang, X.; Zhang, Q. Depression Mechanism of Acid for Flotation Separation of Fluorapatite and Dolomite Using ToF-SIMS and XPS. J. Mol. Liq. 2024, 394, 123584. [Google Scholar] [CrossRef]
  29. Yu, H.; Zhu, Y.; Lu, L.; Hu, X.; Li, S. Removal of Dolomite and Potassium Feldspar from Apatite Using Simultaneous Flotation with a Mixed Cationic-Anionic Collector. Int. J. Min. Sci. Technol. 2023, 33, 783–791. [Google Scholar] [CrossRef]
  30. Singh, A.; Pocock, J. The ‘Crago Process’ and Its Applicability to a South African Sedimentary Phosphate Deposit. Min. Metall. Explor. 2023, 40, 893–900. [Google Scholar] [CrossRef]
  31. Aarab, I.; Derqaoui, M.; El Amari, K.; Yaacoubi, A.; Abidi, A.; Etahiri, A.; Baçaoui, A. Flotation Tendency Assessment Through DOE: Case of Low-Grade Moroccan Phosphate Ore. Min. Metall. Explor. 2022, 39, 1721–1741. [Google Scholar] [CrossRef]
  32. Aarab, I.; El Amari, K.; Yaacoubi, A.; Etahiri, A.; Baçaoui, A. Optimization of the Flotation of Low-Grade Phosphate Ore Using DOE: A Comparative Evaluation of Fatty Acid Formulation to Sodium Oleate. Min. Metall. Explor. 2023, 40, 95–108. [Google Scholar] [CrossRef]
  33. Ding, Z.; Li, J.; Yuan, J.; Yu, A.; Wen, S.; Bai, S. Insights into the Influence of Calcium Ions on the Adsorption Behavior of Sodium Oleate and Its Response to Flotation of Quartz: FT-IR, XPS and AMF Studies. Miner. Eng. 2023, 204, 108437. [Google Scholar] [CrossRef]
  34. He, D.; Zhu, X.; Fu, Y.; Li, Z.; Tang, Y. Effects of Sodium Oleate Surface Properties on the Characteristics of Two-Phase Foam in Froth Flotation. Colloids Surf. A Physicochem. Eng. Asp. 2024, 694, 134119. [Google Scholar] [CrossRef]
  35. Cheng, R.; Li, C.; Liu, X.; Deng, S. Synergism of Octane Phenol Polyoxyethylene-10 and Oleic Acid in Apatite Flotation. Physicochem. Probl. Miner. Process. 2017, 53, 1214–1227. [Google Scholar] [CrossRef]
  36. Jong, K.; Han, Y.; Ryom, S. Flotation Mechanism of Oleic Acid Amide on Apatite. Colloids Surf. A Physicochem. Eng. Asp. 2017, 523, 127–131. [Google Scholar] [CrossRef]
  37. Cao, Q.; Cheng, J.; Wen, S.; Li, C.; Bai, S.; Liu, D. A Mixed Collector System for Phosphate Flotation. Miner. Eng. 2015, 78, 114–121. [Google Scholar] [CrossRef]
  38. Filippova, I.V.; Filippov, L.O.; Lafhaj, Z.; Barres, O.; Fornasiero, D. Effect of Calcium Minerals Reactivity on Fatty Acids Adsorption and Flotation. Colloids Surf. A Physicochem. Eng. Asp. 2018, 545, 157–166. [Google Scholar] [CrossRef]
  39. Eskanlou, A.; Huang, Q.; Foucaud, Y.; Badawi, M.; Romero, A.H. Effect of Al3+ and Mg2+ on the Flotation of Fluorapatite Using Fatty- and Hydroxamic-Acid Collectors—A Multiscale Investigation. Appl. Surf. Sci. 2022, 572, 151499. [Google Scholar] [CrossRef]
  40. Yu, J.; Ge, Y.; Hou, J. Behavior and Mechanism of Collophane and Dolomite Separation Using Alkyl Hydroxamic Acid as a Flotation Collector. Physicochem. Probl. Miner. Process. 2016, 52, 155–169. [Google Scholar] [CrossRef]
  41. Aarab, I.; El Amari, K.; He, D.; Fu, Y.; Boujounoui, K.; Etahiri, A. Eco-Friendly Apatite Flotation: Unlocking the Potential of Spent Coffee Grounds as a Bio-Based Collector. Miner. Eng. 2025, 233, 109652. [Google Scholar] [CrossRef]
  42. Wang, P.; Liu, W.; Zhuo, Q.; Luo, Q.; Sun, X.; Li, J. Mechanism of Interaction between Mixed Collectors and Low-Rank Coal: An Experimental and Simulation Study. Int. J. Coal Prep. Util. 2023, 43, 346–360. [Google Scholar] [CrossRef]
  43. Xu, Y.; Xu, L.; Wu, H.; Wang, Z.; Shu, K.; Fang, S.; Zhang, Z. Flotation and Co–Adsorption of Mixed Collectors Octanohydroxamic Acid/Sodium Oleate on Bastnaesite. J. Alloys Compd. 2020, 819, 152948. [Google Scholar] [CrossRef]
  44. Buckley, A.N.; Hope, G.A.; Parker, G.K.; Steyn, J.; Woods, R. Mechanism of Mixed Dithiophosphate and Mercaptobenzothiazole Collectors for Cu Sulfide Ore Minerals. Miner. Eng. 2017, 109, 80–97. [Google Scholar] [CrossRef]
  45. Sis, H.; Chander, S. Adsorption and Contact Angle of Single and Binary Mixtures of Surfactants on Apatite. Miner. Eng. 2003, 16, 839–848. [Google Scholar] [CrossRef]
  46. Rao, K.H.; Forssberg, K.S.E. Interactions of Anionic Collectors in Flotation of Semi-Soluble Salt Minerals. In Innovations in Flotation Technology; Mavros, P., Matis, K.A., Eds.; Springer: Dordrecht, The Netherlands, 1992; pp. 331–356. [Google Scholar] [CrossRef]
  47. Aarab, I.; Derqaoui, M.; El Amari, K.; Yaacoubi, A.; Abidi, A.; Etahiri, A.; Baçaoui, A. Influence of Surface Dissolution on Reagents’ Adsorption on Low-Grade Phosphate Ore and Its Flotation Selectivity. Colloids Surf. A Physicochem. Eng. Asp. 2021, 631, 127700. [Google Scholar] [CrossRef]
  48. Liu, S.; Zhang, W.; Ren, Q.; Tu, R.; Qiu, F.; Gao, Z.; Xu, S.; Sun, W.; Tian, M. Innovating an Amphoteric Collector Derived from Dodecylamine Molecular Structure: Facilitating the Selective Flotation Separation of Apatite from Quartz and Dolomite. Miner. Eng. 2024, 215, 108819. [Google Scholar] [CrossRef]
  49. Zhang, W.; Tu, R.; Ren, Q.; Liu, S.; Guo, Z.; Liu, P.; Tian, M. The Selective Flotation Separation of Apatite from Dolomite and Calcite Utilizing a Combination of 2-Chloro-9-Octadecenoic Acid Collector and Sodium Pyrophosphate Depressant. Sep. Purif. Technol. 2025, 353, 128446. [Google Scholar] [CrossRef]
  50. Karlkvist, T.; Patra, A.; Rao, K.H.; Bordes, R.; Holmberg, K. Flotation Selectivity of Novel Alkyl Dicarboxylate Reagents for Apatite–Calcite Separation. J. Colloid Interface Sci. 2015, 445, 40–47. [Google Scholar] [CrossRef]
  51. Santos, L.H.; Santos, A.M.A.; de Magalhães, L.F.; de Souza, T.F.; da Silva, G.R.; Peres, A.E.C. Synergetic Effects of Fatty Acids in Amazon Oil-Based Collectors for Phosphate Flotation. Miner. Eng. 2023, 191, 107932. [Google Scholar] [CrossRef]
  52. El-Midany, A.A.; Arafat, Y. Enhancing Phosphate Grade Using Oleic Acid–Sodium Dodecyl Sulfate Mixtures. Chem. Eng. Commun. 2016, 203, 660–665. [Google Scholar] [CrossRef]
  53. Filippova, I.; Filippov, L.; Duverger, A.; Severov, V. Synergetic Effect of a Mixture of Anionic and Nonionic Reagents: Ca Mineral Contrast Separation by Flotation at Neutral pH. Miner. Eng. 2014, 66–68, 135–144. [Google Scholar] [CrossRef]
  54. Farid, Z.; Abdennouri, M.; Barka, N.; Sadiq, M. Grade-Recovery Beneficing and Optimization of the Froth Flotation Process of a Mid-Low Phosphate Ore Using a Mixed Soybean and Sunflower Oil as a Collector. Appl. Surf. Sci. Adv. 2022, 11, 100287. [Google Scholar] [CrossRef]
  55. Guimarães, R.C.; Araujo, A.C.; Peres, A.E.C. Reagents in Igneous Phosphate Ores Flotation. Miner. Eng. 2005, 18, 199–204. [Google Scholar] [CrossRef]
  56. Gregory, G.R.E.C. The Determination of Residual Anionic Surface-Active Reagents in Mineral Flotation Liquors. Analyst 1966, 91, 251. [Google Scholar] [CrossRef]
  57. DuBois, M.; Gilles, K.A.; Hamilton, J.K.; Rebers, P.A.; Smith, F. Colorimetric Method for Determination of Sugars and Related Substances. Anal. Chem. 1956, 28, 350–356. [Google Scholar] [CrossRef]
  58. Aarab, I.; Derqaoui, M.; Abidi, A.; Yaacoubi, A.; El Amari, K.; Etahiri, A.; Baçaoui, A. Direct Flotation of Low-Grade Moroccan Phosphate Ores: A Preliminary Micro-Flotation Study to Develop New Beneficiation Routes. Arab. J. Geosci. 2020, 13, 1252. [Google Scholar] [CrossRef]
  59. Derqaoui, M.; Aarab, I.; Abidi, A.; Yaacoubi, A.; El Amari, K.; Etahiri, A.; Baçaoui, A. Valorization of Seaweeds Biomass as Source an Eco-Friendly and Efficient Depressant of Calcite in the Flotation of Apatite Containing Ore. Waste Biomass Valorization 2022, 13, 2623–2636. [Google Scholar] [CrossRef]
  60. Gao, Z.; Li, C.; Sun, W.; Hu, Y. Anisotropic Surface Properties of Calcite: A Consideration of Surface Broken Bonds. Colloids Surf. A Physicochem. Eng. Asp. 2017, 520, 53–61. [Google Scholar] [CrossRef]
  61. Antti, B.-M.; Forssberg, E. Pulp Chemistry in Industrial Mineral Flotation. Studies of Surface Complex on Calcite and Apatite Surfaces Using FTIR Spectroscopy. Miner. Eng. 1989, 2, 217–227. [Google Scholar] [CrossRef]
  62. Wang, L.; Lyu, W.; Li, F.; Liu, J.; Zhang, H. Discrepant Adsorption Behavior of Sodium Alginate onto Apatite and Calcite Surfaces: Implications for Their Selective Flotation Separation. Miner. Eng. 2022, 181, 107553. [Google Scholar] [CrossRef]
  63. Owens, C.L.; Nash, G.R.; Hadler, K.; Fitzpatrick, R.S.; Anderson, C.G.; Wall, F. Apatite Enrichment by Rare Earth Elements: A Review of the Effects of Surface Properties. Adv. Colloid Interface Sci. 2019, 265, 14–28. [Google Scholar] [CrossRef]
  64. Jiang, H.; Xu, Y.; Li, M.; Wang, Y. Microscopic Perspective of the Combined Collector CTAB/SPA on the Flotation Separation of Fluorite and Calcite: Adsorption Morphology and Interaction Force. Colloids Surf. A Physicochem. Eng. Asp. 2024, 688, 133534. [Google Scholar] [CrossRef]
  65. Cao, Q.; Luo, B.; Wen, S.; Cheng, J. Influence of Synergistic Effect between Dodecyl Amine and Sodium Oleate on Improving the Hydrophobicity of Fluorapatite. Physicochem. Probl. Miner. Process 2016, 53, 42–55. [Google Scholar] [CrossRef]
  66. Lerma-García, M.; Ramis-Ramos, G.; Herrero-Martinez, J.M.; Simó-Alfonso, E.F. Authentication of Extra Virgin Olive Oils by Fourier-Transform Infrared Spectroscopy. Food Chem. 2010, 118, 78–83. [Google Scholar] [CrossRef]
  67. Zhang, Q.; Liu, C.; Sun, Z.; Hu, X.; Shen, Q.; Wu, J. Authentication of Edible Vegetable Oils Adulterated with Used Frying Oil by Fourier Transform Infrared Spectroscopy. Food Chem. 2012, 132, 1607–1613. [Google Scholar] [CrossRef]
  68. Rohman, A.; Man, Y.B.C. Fourier Transform Infrared (FTIR) Spectroscopy for Analysis of Extra Virgin Olive Oil Adulterated with Palm Oil. Food Res. Int. 2010, 43, 886–892. [Google Scholar] [CrossRef]
  69. Kou, J.; Tao, D.; Xu, G. Fatty Acid Collectors for Phosphate Flotation and Their Adsorption Behavior Using QCM-D. Int. J. Miner. Process. 2010, 95, 1–9. [Google Scholar] [CrossRef]
  70. Chen, W.; Feng, Q.; Zhang, G.; Yang, Q.; Zhang, C. The Effect of Sodium Alginate on the Flotation Separation of Scheelite from Calcite and Fluorite. Miner. Eng. 2017, 113, 1–7. [Google Scholar] [CrossRef]
Minerals 15 00822 g001
Figure 1. XRD patterns of fluorapatite, calcite, and quartz.
Figure 1. XRD patterns of fluorapatite, calcite, and quartz.
Minerals 15 00822 g001
Minerals 15 00822 g002
Figure 2. Apatite, calcite, and quartz flotation as a function of FAM concentration.
Figure 2. Apatite, calcite, and quartz flotation as a function of FAM concentration.
Minerals 15 00822 g002
Minerals 15 00822 g003
Figure 3. Micro-flotation results as a function of pH with/without NaAl (FAM: 80 mg/L; NaAl: 30 mg/L).
Figure 3. Micro-flotation results as a function of pH with/without NaAl (FAM: 80 mg/L; NaAl: 30 mg/L).
Minerals 15 00822 g003
Minerals 15 00822 g004
Figure 4. Micro-flotation results as a function of NaAl concentration (FAM: 80 mg/L; pH: 11).
Figure 4. Micro-flotation results as a function of NaAl concentration (FAM: 80 mg/L; pH: 11).
Minerals 15 00822 g004
Minerals 15 00822 g005
Figure 5. Adsorption of FAM with/without NaAl onto pure minerals.
Figure 5. Adsorption of FAM with/without NaAl onto pure minerals.
Minerals 15 00822 g005
Minerals 15 00822 g006
Figure 6. Zeta potential with/without different reagents: (a) apatite, (b) calcite, and (c) quartz.
Figure 6. Zeta potential with/without different reagents: (a) apatite, (b) calcite, and (c) quartz.
Minerals 15 00822 g006
Minerals 15 00822 g007
Figure 7. FTIR spectra of (a) fluorapatite, (b) calcite, and (c) quartz nonconditioned/conditioned with FAM and NaAl + FAM.
Figure 7. FTIR spectra of (a) fluorapatite, (b) calcite, and (c) quartz nonconditioned/conditioned with FAM and NaAl + FAM.
Minerals 15 00822 g007
Table 1. Chemical composition of pure specimens of fluorapatite, calcite, and quartz.
Table 1. Chemical composition of pure specimens of fluorapatite, calcite, and quartz.
MineralsComposition, %
P2O5CaOSiO2MgOFe2O3Al2O3MnOK2ONa2O
Fluorapatite41.8656.700.720.100.010.120.010.040.63
Calcite0.1399.050.410.040.010.250.020.050.05
Quartz0.010.0799.320.020.350.220.020.020.00
Table 2. Reagents used in the flotation experiments.
Table 2. Reagents used in the flotation experiments.
ReagentRoleFormulaPurity
Sodium alginate (NaAl)Depressant(NaC6H7O6)nAlginic acid sodium salt from brown algae, low viscosity
Methyl isobutyl carbinol (MIBC)FrotherC6H14OAR grade 98%
Sodium hydroxidepH controllerNaOHACS reagent ≥ 97%
Table 3. Composition of FAM.
Table 3. Composition of FAM.
Fatty AcidOleic Acid C18:1Linoleic Acid C18:2Palmitic Acid C16:0Stearic Acid C18:0Palmitoleic Acid C16:1
Content, %wt.811042<1
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Aarab, I.; El Amari, K.; Yaacoubi, A.; Baçaoui, A.; Etahiri, A. Harnessing Mixed Fatty Acid Synergy for Selective Flotation of Apatite from Calcite and Quartz with Sodium Alginate. Minerals 2025, 15, 822. https://doi.org/10.3390/min15080822

AMA Style

Aarab I, El Amari K, Yaacoubi A, Baçaoui A, Etahiri A. Harnessing Mixed Fatty Acid Synergy for Selective Flotation of Apatite from Calcite and Quartz with Sodium Alginate. Minerals. 2025; 15(8):822. https://doi.org/10.3390/min15080822

Chicago/Turabian Style

Aarab, Imane, Khalid El Amari, Abdelrani Yaacoubi, Abdelaziz Baçaoui, and Abderahman Etahiri. 2025. "Harnessing Mixed Fatty Acid Synergy for Selective Flotation of Apatite from Calcite and Quartz with Sodium Alginate" Minerals 15, no. 8: 822. https://doi.org/10.3390/min15080822

APA Style

Aarab, I., El Amari, K., Yaacoubi, A., Baçaoui, A., & Etahiri, A. (2025). Harnessing Mixed Fatty Acid Synergy for Selective Flotation of Apatite from Calcite and Quartz with Sodium Alginate. Minerals, 15(8), 822. https://doi.org/10.3390/min15080822

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop