Mixed Minerals Flotation Research Articles

Selective galena depression mechanism of tea polyphenol in chalcopyrite flotation

In this study, the selective galena depression mechanism of tea polyphenol (TP) was investigated in chalcopyrite flotation. The feasibility of using TP as a galena depressant was studied through flotation experiments, and the depressant mechanism of TP on galena was analyzed using contact angle measurements, zeta potential measurements, adsorption experiments, X-ray photoelectron spectroscopy (XPS) analysis, and time-of-flight secondary ion mass spectrometry (ToF-SIMS) tests. Artificially mixed mineral flotation tests were performed at a pH of 8, TP concentration of 4 × 10–4 mol/L, and SIX concentration of 2 × 10–4 mol/L, resulting in a copper concentrate with a recovery of 83.07 % and a copper grade of 29.32 %. The lead recovery and grade of the copper concentrate were 8.87 % and 7.87 %, respectively, demonstrating the feasibility of using TP as a galena depressant. The zeta potential measurements and adsorption experiments showed that the adsorption of SIX on the surface of chalcopyrite was less affected by the TP treatment, while the TP significantly hindered the adsorption of SIX on the surface of galena, which the galena ToF-SIMS test results further support.

Mechanisms for the selective separation of spodumene from feldspar by sodium N-oleoylsarcosinate as an efficient collector

The primary source of lithium is spodumene, a mineral commonly associated with aluminosilicate minerals like feldspar. Flotation is widely regarded as the most effective method for separating spodumene from feldspar. The efficiency of this separation process is largely dependent on the choice of flotation reagents. In this work, an efficient collector, sodium N-oleoylsarcosinate (SNOS), was employed to achieve the separation of spodumene and feldspar. To investigate the flotation behavior and underlying mechanism, comprehensive approaches involving flotation tests, solution chemical calculation, Fourier transform infrared spectroscopy (FTIR), contact angle measurements, atomic force microscope (AFM), and density functional theory (DFT) calculations were launched. Operating under optimal conditions, Li2O demonstrated a recovery of 88.59% and a concentrate grade of 7.12% in the mixed minerals flotation. Due to more O and Al active sites on spodumene, SNOS exhibited strong chemisorption and multilayer adsorption on Ca(II)-activated spodumene. Remarkably, SNOS, with its three oxygen sites, displayed a robust reaction with Ca(Ⅱ)-activated spodumene, boasting an adsorption energy as substantial as −789.41 kJ/mol. In contrast, the interaction of SNOS with Ca(Ⅱ)-activated feldspar was negligible. Therefore, the proficient SNOS collector with notable selectivity, holds immense potential for practical application in the flotation of real spodumene ores.

Effective Flotation Separation of Chalcopyrite and Graphite Using Eco-Friendly Xanthan Gum as Depressant

ABSTRACT The concentrate grade in chalcopyrite flotation is often compromised by the associated inherently floatable gangue such as graphite. In this study, eco-friendly xanthan gum (XG) was introduced as a graphite depressant in the flotation of chalcopyrite. Single minerals flotation showed that XG strongly reduced the floatability of graphite at pH 7.5 with no significant effect on the flotation of chalcopyrite. Mixed minerals flotation showed that the addition of 20 mg/L XG increased copper grade and selectivity index by 16.83% and 14.23, respectively. This selective depressing behavior of XG was due to the strong affinity between XG and graphite as well as the weak interaction between XG and chalcopyrite, as suggested by electrokinetic and adsorption measurements. FTIR and XPS analyses indicated that the adsorption of XG on the graphite surface could be governed by physical adsorption mechanisms. Furthermore, since the contribution of hydrogen bonding interaction was insignificant, hydrophobic interaction was considered as the dominant driving force in the adsorption process. This investigation demonstrates the promising potential of XG for graphite depression and may contribute to the greening of chalcopyrite flotation process.

Adsorption mechanisms of activated surface of quartz and feldspar with mixed NaOL/DDA

In this paper, the flotation separation of quartz and feldspar was studied with CaCl2 as activators and mixed sodium oleate/ dodecylamine (NaOL/DDA) collectors under alkaline condition, and the action mechanism of mixed NaOL/DDA collectors on the quartz and feldspar surfaces were systematically explored. The results of micro-flotation test showed that there were 90.98% quartz and 13.08% feldspar were floated with 0.5 mmol/L CaCl2 and 2.8 mmol/L mixed NaOL/DDA collectors with molar ratio of 8/1 at pH 10.0. And the artificial mixed minerals flotation manifested these two minerals were able to efficient separation with CaCl2 and mixed NaOL/DDA collectors at pH 10 ∼ 11. These outcomes indicated that DDA could increase recovery of quartz obviously and reduce about a half dosage of NaOL (from 0.5 mmol/L to 0.25 mmol/L) in flotation under alkaline condition; Meanwhile, mixed NaOL/DDA collectors were able to decreased the flotation separation pH from 12 to 10 on quartz and feldspar. Infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) results revealed that when NaOL collector was added alone, it could adsorb on activated quartz surface but hardly detected on feldspar surface at pH 10. However, they all were found on both quartz and felspar surface when mixed NaOL/DDA collectors were introduced as collectors. Quartz microcrystal balance with dissipation (QCM-D) experiment confirmed that mixed NaOL/DDA collectors showed a higher adsorption mass and more stable adsorption layer on quartz compared with NaOL was introduced as collector alone. In addition, whether CaCl2, NaOL or mixed NaOL/DDA, the adsorption mass on quartz sensor were larger than that on feldspar senor, which might cause difference of hydrophobicity on the surface of quartz and feldspar in flotation. The above experiments showed that the mixed NaOL/DDA collectors can significantly improve hydrophobic difference between quartz and feldspar after activating with CaCl2 and expand the floated pH range of quartz compared with using NaOL as collector alone, which were efficient reagents to separate quartz and feldspar in flotation.

Exploring the effect of a polyacrylic acid-based grinding aid on magnetite-quartz flotation separation

It is well documented that the use of grinding aids (GAs) can reduce milling energy consumption. However, the impact of GAs on downstream processes must be addressed in view of complex processes such as froth flotation separation. This study investigates the effects of polyacrylic-based grinding aids (Zalta™ GR20-587: AAG) on the grinding performance and quartz flotation from magnetite. Various AAG dosages and conditions were examined. The grinding results showed lower energy consumption and a finer, more uniform product size with roughened surfaces for AAG compared to grinding without the grinding aid. Flotation tests of single pure minerals showed that AAG enhanced quartz collection with minimal effect on magnetite. Mixed mineral flotation showed that by using AAG, Fe recovery of 92.1 % and 64.5 % Fe grade could be achieved with a lower collector dosage of 100 g/t compared to 200 g/t in the absence of AAG. Zeta potentials and stability measurements showed that AAG shifts the potential, thus improving the stability and dispersion of the suspension. Adsorption tests illustrated that AAG adsorbed on both quartz and magnetite, the former having a higher capacity. FTIR indicated the physisorption interaction between AAG and the minerals. Therefore, the presence of AAG not only improved grinding efficiency but could potentially decrease the amount of collector required to achieve comparable metallurgical performance.

Efficient separation of magnesite and quartz using eco-friendly Dimethylaminopropyl lauramide experimental and mechanistic studies

To achieve efficient separation of magnesite from quartz, a novel cationic collector—Dimethylaminopropyl lauramide (DPLA), was introduced into the quartz-magnesite reverse flotation system. The flotation performance and adsorption mechanism of DPLA on the minerals surfaces were investigated by micro-flotation tests, contact angle measurements, zeta-potential measurements, Fourier transform infrared spectroscopy (FTIR) analysis, Atomic force microscope (AFM), and Density functional theory (DFT) calculation. The single mineral micro-flotation results showed that when DPLA concentration was 25 mg/L, 94.6% of quartz was removed and 97.14% of magnesite was recovered under natural pulp pH. Further, the artificial mixed mineral flotation results demonstrated that DPLA had a superior selectivity for quartz and the concentrate with 44.36% MgO grade and 98.69% MgO recovery was obtained at 25 mg/L DPLA, and the separation efficiency was 89.52%. Contact angle measurement results suggested that the hydrophobicity of quartz surface increased significantly after treatment with DPLA and indicated the interaction between DPLA and quartz was stronger than that with magnesite. The results of zeta-potential measurements, FTIR, AFM, and DFT calculation revealed that the adsorption of DPLA on the quartz surface was mainly by the electrostatic force and hydrogen bonding interactions. In addition, the advantages of DPLA as the collector were analyzed in terms of environmental aspects and economics. DPLA has great potential for industrial application to effectively separate magnesite from quartz.

Mechanism of HCA and CEPPA in flotation separation of cassiterite and fluorite

As an essential raw material for the tin industry, cassiterite ore needs to be effectively separated and purified, and the removal of impurities such as fluorite becomes the key to cassiterite flotation. In this study, the flotation separation of cassiterite (SnO2) and fluorite (CaF2) was enhanced by using hydroxylcitric acid (HCA) as fluorite inhibitor and 2-carboxyphenyl phosphonic acid (CEPPA) as collector. With a reagent scheme of 120 mg/L CEPPA and 4.5 mg/L HCA at pH 10.0, the flotation recovery of cassiterite and fluorite was 92.80% and 13.57%, respectively. Under the same experimental conditions of artificially mixed mineral flotation, the flotation index of cassiterite concentrate grade 78.19% and recovery 90.29% was obtained. The selective adsorption mechanism of CEPPA and HCA on minerals was investigated by Zeta potential, Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The results showed that CEPPA anions had chemically adsorbed on cassiterite and fluorite, and the adsorption of HCA on fluorite surface was stronger than that on cassiterite surface. XPS analyses further confirmed that Ca sites exposed on fluorite had a stronger affinity for HCA than cassiterite. Furthermore, the addition of HCA had little effect on the adsorption of CEPPA on cassiterite, while the strong chemisorption of HCA on fluorite surface prevented the adsorption of CEPPA on fluorite. These results provide a theoretical basis and promising new strategy for the flotation separation of cassiterite and fluorite.

A novel method to improve the flotation separation of chalcopyrite from arsenopyrite under low-alkalinity conditions

In this paper, we report a novel method to improve the flotation separation of chalcopyrite from arsenopyrite under low-alkalinity conditions. Single mineral flotation experiment results showed that individual use of CTP had weak inhibition on arsenopyrite flotation while no inhibition on chalcopyrite flotation. However, the addition of Ca2+ greatly enhanced the inhibition of CTP on arsenopyrite flotation while slightly affected chalcopyrite flotation. The artificial mixed mineral flotation experiment results showed that a concentrate with Cu grade of 29.01% and As grade of 7.51% was obtained, with Cu recovery of 80.20% and separation efficiency of 41.75%. Compared with no addition of Ca2+ and CTP, the Cu grade in the concentrate was increased by 10.53%, the As grade was decreased by 13.94%, and the separation efficiency was increased by 38.3%. This further demonstrated that utilization of Ca2+ as an assistant depressant of CTP can well improve the flotation separation of chalcopyrite from arsenopyrite, which is consistent with the single mineral flotation experiment results. It is expected that this study will be helpful for the arsenic removal in the industrial production practice of arsenic-bearing copper sulfide ore.

Depressant behavior of crude fucoidan in the separation of talc and molybdenite

Molybdenite is an important strategic resource. In the field of mineral processing, flotation is commonly used to enrich and extract molybdenite in the ore. In the flotation process, it is very difficult to separate talc and molybdenite because of their similar structures and natural floatability. Here a novel depressant CF with rich output and low value was demonstrated, which has never been reported in the field of mineral processing, for flotation separation of talc and molybdenite. In this study, single and manually mixed mineral flotation tests, contact angle tests, adsorption measurements, FTIR and XPS analyses were used. It was found that molybdenite can be separated from talc by reverse flotation with 20 mg/L CF as molybdenite depressant, and it can be determined that CF has the main chemisorption on the surface of molybdenite. This finding has important progressive significance for the flotation separation of molybdenite and talc.

Sodium N-Lauroylsarcosinate (SNLS) as a Selective Collector for Calcareous Phosphate Beneficiation

Sodium N-lauroylsarcosinate (SNLS) was employed as a selective flotation collector for dolomite–apatite separation. The influence of pH, condition time, and collector dose on the flotation performance of both apatite and dolomite minerals was investigated using single mineral and binary mixed mineral flotation experiments. The performance of SNLS was compared to sodium oleate (NaOL), as a standard collector. In this study, the adsorption mechanism of SNLS on both minerals was studied using zeta-potential and FT-IR measurements. The results showed that SNLS prefers to adsorb on the dolomite mineral. The maximum difference in floatability was 83% for single dolomite and apatite minerals at pH 10 in the presence of 0.05 mmol/L SNLS. Binary mixtures of dolomite and apatite minerals of different ratios were applied, to evaluate their separation efficiency. The SNLS could separate dolomite from its mixtures with apatite minerals. Using 0.2 mmol/L of SNLS at pH 10, a concentrate of 30.9% P2O5 and 0.79% MgO was obtained from a natural phosphate ore having 25.8% P2O5 and 5.16% MgO.

The selective depression effect of dextrin on pyrite during the Zn–Fe sulfides flotation under low alkaline conditions

As an environmentally friendly scale inhibitor, characterized by low cost, high efficiency and no secondary pollution, dextrin was utilized as a depressant in the flotation separation of mixed Zn-S concentrate. The microflotation results clearly demonstrate that dextrin exerted a good inhibitory effect on pyrite and sphalerite could be separated successfully from pyrite in low alkaline environment. The mixed mineral flotation results further indicate that sphalerite could be efficiently separated from its synthetic mixture with pyrite via the use of dextrin as the depressant in the pH range of 7–9. The contact Angle test shows that dextrin can be adsorbed on the surface of Cu-activated pyrite to enhance hydrophobicity, but not on the surface of Cu-activated sphalerite. The results of infrared spectroscopy investigations and XPS analyses indicate that under low alkali conditions, copper ions activate sphalerite, and copper sulfide polysulfide forms on sphalerite surface without Cu(OH)2 formation. Cu(OH)2, Fe(OH)2 and CuS were generated on pyrite surface due to the activation of copper ions. The adsorption between dextrin and metal hydroxyl compounds was the main cause of pyrite inhibition， which is attributed to the hydrophilic hydroxyl group in the dextrin molecule. According to these results, dextrin can be used as a selective depressant for pyrite during sphalerite flotation in low alkaline environment.

Investigations of amino trimethylene phosphonic acid as a green and efficient depressant for the flotation separation of apatite from calcite

Flotation separation of apatite from calcite is difficult due to their same activate calcium atoms on the surface. To address this issue, amino trimethylene phosphonic acid (ATMP) was introduced to separate apatite and calcite in this research. The microflotation results showed that NaOl had an excellent collecting ability to apatite and calcite. Meanwhile, the tests also found that ATMP had a strong depression ability to calcite, but it hardly influenced the apatite floatability. The artificial mixed minerals flotation results confirmed that ATMP could be used as a depressant to separate apatite and calcite in the presence of NaOl. Zeta potential measurements illustrated that the addition of ATMP prevented the NaOl adsorption onto the calcite surface, while it hardly affected the interaction of NaOl with the apatite surface. Solution chemistry calculation of ATMP was conducted to reveal the main species of ATMP, while XPS analysis further indicated the strong chemisorption of ATMP onto calcite rather than apatite. Hence, the selective depression ability of ATMP was attributed to the electrostatic repulsion and steric resistance for the apatite surface and the stable adsorption structure at the calcite surface.

Selective depression action of taurine in flotation separation of specularite and chlorite

Chlorite, as the most representative gangue mineral associated with specularite, of which the separation of these two minerals is difficult. This paper investigated the depression effect of taurine on specularite/chlorite separation via flotation experiments, adsorption tests, contact angle measurements, Zeta potential detection, FT-IR measurements, and XPS analyses. The results of single mineral flotation indicated that chlorite could be depressed selectively by taurine with the recovery of less than 30%, but the floatability of specularite remains high with recovery rate of 81.77% at pH 10. The artificial mixed mineral flotation results confirmed the effectiveness of taurine as a depressant. Surface adsorption, contact angle, and Zeta potential detection revealed taurine primarily adsorbs on the chlorite surface, which hampered the DDA’s subsequent adsorption and results in the chlorite’s poor floatability. The FT-IR spectra and XPS analyses provided further proof that taurine adsorbed on chlorite surface as an electron donor, and part of the electrons transferred from the sulfonic acid group of taurine to metal ions during the adsorption process. In addition, the hydrogen bond between amino-group of taurine and O ions in chlorite surface was also formed in the adsorption process. Finally, optimized adsorption configurations of taurine on chlorite surfaces were proposed.

Flotation Separation of Dolomite from Fluorapatite Using Sodium Dodecyl Benzene Sulfonate as the Efficient Collector under Low Temperature

Flotation is the most often employed process to achieve the selective removal of contaminants from the raw materials used in the manufacturing of phosphate fertilizer. However, sodium oleate (NaOL), as a typical collector, is ineffective because of its low collecting ability under low temperature. As a result, developing and implementing feasible alternatives is critical for the long-term output of mines. In this study, sodium dodecyl benzene sulfonate (SDBS), a low-cost and freely soluble reagent under low temperature was used to examine its collecting ability and selectivity in a fluorapatite-dolomite system by means of single and artificially mixed minerals flotation. The adsorption mechanism was evaluated with the help of XPS analyses. The flotation results demonstrate that SDBS could float both fluorapatite and dolomite, but show a higher affinity towards fluorapatite instead of dolomite. Moreover, SDBS could preferred adsorb onto fluorapatite surface when fluorapatite and dolomite coexist. SDBS is more suitable than NaOL for satisfactory recovery of fluorapatite under low temperature in terms of the higher recovery obtained. The XPS analyses results demonstrate that the adsorption of SDBS on fluorapatite surface was more intensively as opposed to that on dolomite surface and Ca active sites on fluorapatite surface are supposed to be the main location for SDBS attachment.

Selective flotation separation of chalcopyrite from talc by a novel depressant: N-methylene phosphonic chitosan

• NMPC can conduct effectively flotation separation of chalcopyrite from talc. • NMPC can selectively adsorb on the surface of talc. • The flocculation effect of NMPC can accelerate the precipitation of talc. • A physisorption process for NMPC– talc interaction is revealed by surface analysis. In this work, we investigated the flotation performance and selective adsorption mechanism of a chitosan derivative NMPC (N-methylene phosphonic chitosan) as an novel talc depressant in the flotation separation of chalcopyrite from talc. The single mineral flotation experiments demonstrated that without the talc depressant, both chalcopyrite and talc showed excellent floatability, thus the separation was difficult in the pH range of 3–11. When NMPC was added, the recovery of talc was reduced drastically but the recovery of chalcopyrite decreased slightly in the pH range of 3–9 at a concentration of 10 mg/L in pulp. Artificial mixed mineral flotation experiments also demonstrated that the effective separation of talc and chalcopyrite could be achieved when NMPC was employed as the depressant. The results showed that better grade and recovery were obtained in different proportions of chalcopyrite and talc, which meant the NMPC is better than CMC, Arabic gum in flotation separation of talc and chalcopyrite. Analysis of adsorption tests, FT-IR measurements, and XPS measurements suggested that NMPC was selectively adsorbed on the talc surface by physical adsorption which might result from the hydrogen bonding and hydrophobic interaction between NMPC and talc. Moreover, the sedimentation experiments disclosed that NMPC plays an important role in the flocculation and settling of fine talc.

Selective flotation separation of bastnaesite from dolomite using β-naphthyl sulfonate formaldehyde condensate as depressant: Experimental and calculational studies

It is difficult to recover bastnaesite from dolomite when using octyl hydroxamic acid (OHA) as collector owing to the similar chemical properties between bastnaesite and dolomite. In this work, β-naphthyl sulfonate formaldehyde condensate (NSFC), as an effective depressant for dolomite has been employed. The flotation performance of NSFC in bastnaesite-dolomite system has been investigated with the help of single minerals flotation and artificially mixed minerals flotation. The depression mechanism has been first proposed from micro level by means of XPS analyses and molecular dynamic simulations. The flotation results demonstrate that NSFC showed a higher affinity towards dolomite instead of bastnaesite, and rare earth element can be effectively recovered using NSFC as depressant in bastnaesite-dolomite system. Mg active sites existing on dolomite surface are more prone to reacting with NSFC depressant through chemical bonding. The distance between Mg active sites on dolomite surface and oxygen components in sulfo groups became closer after interaction, which is opposite to that of Ca active sites, indicating that Mg active sites are the predominant place for NSFC attachment. The findings reveal that NSFC in conjunction with OHA could be used as an effective flotation reagent scheme for satisfactory recovery of bastnaesite when dolomite is the main associated gangue mineral.

Improving the flotation separation of chalcopyrite from galena through high-temperature air oxidation pretreatment

A method of air oxidation pretreatment at 170 °C was developed for the selective separation of chalcopyrite and galena. Single mineral and artificially mixed mineral flotation experiments indicated that the hydrophobicity of chalcopyrite was greatly reduced, and galena maintained outstanding floatability after pretreatment by high-temperature air oxidation. Hence, the efficient flotation separation of chalcopyrite and galena was achieved. Zeta potential and FTIR analysis illustrated that the chemisorption strength of collector sodium butyl xanthate (SBX) on the surface of galena was higher than that on chalcopyrite based on the oxidation pretreatment method. XPS analysis proved that oxidation could occur on the surfaces of chalcopyrite and galena with pretreatment by high-temperature air oxidation, but the oxidation extent of chalcopyrite was greater than that of galena. Moreover, the FeOOH and CuO hydrophilic species formed on the chalcopyrite surface greatly increased the hydrophilicity of chalcopyrite and impeded the adsorption of SBX on the chalcopyrite surface. By contrast, the galena surface was extremely difficult to oxidize to PbO during air oxidation at 170 °C due to the high stability, and the chemical reaction of SBX on the galena surface was still violent. Therefore, the flotation separation of chalcopyrite and galena can be efficiently realized using high-temperature air oxidation method to treat minerals.

Investigation on the flotation separation of smithsonite from calcite using calcium lignosulphonate as depressant

The flotation separation of smithsonite and calcite is difficult due to their similar surface physicochemical characteristics. In this study, calcium lignosulphonate (CLS) was employed as a selective inhibitor for the flotation separation of smithsonite from calcite using sodium oleate (NaOl) as collector. Flotation experiments results indicate that the calcite flotation was strongly depressed by CLS, whereas the smithsonite flotation was barely interfered. The flotation separation of smithsonite from calcite could be achieved at pH 10. A concentrate with zinc grade and recovery of 45.16% and 85.60% respectively was obtained in the artificial mixed minerals flotation experiment in the presence of CLS. The interaction mechanism was investigated by zeta potential measurement, Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) and results suggest that CLS chemically absorbed on the calcite surface in the form of Ca-SO3, which strongly hindered the successive NaOl adsorption on the calcite. However, it barely absorbed on the smithsonite surface, thus exhibiting little influence on the reaction between NaOl and smithsonite. Hence, CLS could be utilized as a selective depressant for calcite in the flotation of smithsonite.

Effect of Na2SO3 on the floatability of chalcopyrite and enargite

The effect of sodium sulfite (Na2SO3) on the floatability of chalcopyrite and enargite was investigated in this work. The micro flotation tests of single and mixed minerals were performed under various concentrations of Na2SO3. The micro flotation tests of single minerals showed that Na2SO3 depressed the floatability of both minerals at pH 9 in the absence of potassium amyl xanthate (PAX). Interestingly, the addition of PAX followed by the Na2SO3 treatment selectively improved the recovery of enargite. On the other hand, the recovery of chalcopyrite remained low under a similar condition. The single mineral flotation results indicate that separation of chalcopyrite and enargite might be possible using PAX and Na2SO3 treatment. Indeed, the mixed mineral flotation results were in agreement with the flotation results of single minerals. The mineral surface was analyzed by X-ray photoelectron spectroscopy (XPS) after the treatments to explain the phenomenon. The XPS results show the presence of sulfate species on both mineral surfaces after the Na2SO3 treatment. The adsorbed PAX could prevent the formation of this sulfate species on the enargite surface and rendered the surface hydrophobic. However, the adsorbed PAX could not prevent the formation of sulfate species on the chalcopyrite surface and rendered the surface hydrophilic.

Effects of barite size on the fluorite flotation using the reagent scheme of GS/NaOl

Barite is easily ground to slime fraction, which may affect the fluorite flotation. The role of barite particle size in the fluorite flotation was studied in this work. Single mineral flotation showed that gelatinized starch (GS) selectively depressed the barite flotation with different size fractions while it had little effect on fluorite flotation using sodium oleate (NaOl) as the collector, suggesting the sufficient separation of fluorite from barite using the reagent scheme of GS/NaOl. However, the flotation of mixed minerals presented that the existing of fine barite particle significantly interfere with the fluorite flotation. Zeta potential measurements, turbidity tests, and light microscope observations revealed that the hetero-coagulation occurred between fluorite and barite slimes, causing the slime coating of barite onto the fluorite surface. GS not only acted as the depressant but also act as the flocculant to improve the apparent size of barite, while it still could not completely eliminate the detrimental effects of slime coating due to the entrainment of fluorite-barite aggregates. The additional methods to obtain the effective flotation separation of fluorite from barite slime were tested and discussed. • Roles of barite size on the fluorite flotation using the reagent scheme of GS/NaOl were studied. • The barite particle size significantly affected the fluorite flotation in mixed mineral flotation. • The hetero-coagulation between fluorite and barite slimes caused the adverse “slime coating”. • GS could act as depressant and flocculant to enhance the flotation separation efficiency. • Additional approaches were tested and discussed to further eliminate the slime coating effects.