Fluorite Flotation Research Articles

Evaluation of a novel depressant PMAA for the separation of fluorite from calcite using NaOl as a collector

It is challenging to separate fluorite from calcite due to their same calcium activated sites on their surfaces. The copolymer of maleic and acylic acid (PMAA) was used to inhibit the calcite in the flotation of fluorite. Micro-flotation results exhibited that sodium oleate (NaOl) had a good ability to collect fluorite and calcite in the scope of pH 7-10. The PMAA treatment prior to NaOl selectively depressed the floatability of calcite while allowed the flotation of fluorite, and the artificial minerals mixture plotted that fluorite/calcite could be effectively separated in the presence of PMAA/NaOl. Zeta potential results suggested that NaOl collector was absorbed on the PMAA-conditioned calcite surface but did not adsorb on the PMAA-conditioned fluorite surface. XPS results and calculational chemistry revealed the chemical interaction occurred between calcite surface and PMAA which was attributed to the calcium ions of calcite surface interacting with -COOH group of PMAA.

Study on flotation separation of barite fluorite by citric acid under new collector system

Barite and fluorite have similar physical and chemical properties and floatability, and traditional flotation reagents are difficult to effectively separate these two minerals. In order to realize the effective separation of the two minerals, a new system with high selectivity and strong collecting ability, α-BLA ( bromododecanoic acid) system, was selected in this paper. The system can be applied at a wide range of pH values and can greatly eliminate the interference of metal ions. Therefore, this study selected this stable system to explore the effect of citric acid on barite fluorite flotation, in order to more objectively explain the adsorption mechanism of the agent. The results show that the floatability of the two minerals is quite different under the action of citric acid. Barite concentrate with grade of 81.12% and recovery of 87.74% can be obtained by micro-flotation experiment. On this basis, the interaction mechanism between citric acid and mineral surface was further studied by contact angle test, Zeta potential test, Fourier transform infrared ( FTIR), X-ray photoelectron spectroscopy ( XPS) and density functional theory ( DFT) calculation. The results show that when citric acid reacts on the surface of barite, its adsorption energy increases with the increase of bond number. The reaction on the surface of fluorite produces 3-hydroxyglutaric acid, which transfers a certain amount of electrons to Ca1 and Ca2 ions on the surface of fluorite, enhancing the chemical adsorption of citric acid on the surface of fluorite. This paper provides a theoretical basis and effective guidance for the flotation separation of barite fluorite.

Investigating the Mechanism of Diethylenetriamine Pentamethylene Phosphonic Acid as a Depressant for Calcite Flotation of Fluorite.

Fluorite and calcite have been attracting research attention for a long time. This paper reports on an investigation of the use of diethylene triamine pentamethylphosphonic acid (DTPMPA) as a chelating inhibitor. DTPMPA was used as a chelating inhibitor to study the flotation, separation, and adsorption behaviors of fluorite and calcite minerals. The microflotation experiment showed that the maximum separation of fluorite and calcite can be achieved with a DTPMPA dosage of 1.5 × 10-4 mol/L under weakly alkaline conditions (pH = 8). Zeta potential measurement, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy were used to confirm that DTPMPA was adsorbed on the surface of calcite, inhibiting NaOl adsorption. Additionally, density functional theory calculations showed that oxygen in the DTPMPA phosphate group formed the most stable bidentate binuclear adsorption configuration by chelating with calcium on the calcite surface. Through detection analysis and simulation calculations, the results showed that DTPMPA exhibited significantly weaker adsorption on fluorite compared to that on calcite, highlighting its selective inhibition ability on calcite.

Effect of an Environment-Friendly Depressant on the Flotation of Bastnaesite and Fluorite

To overcome the difficulty of separating bastnaesite from fluorite through the flotation technique, the present study examined the suitability of sodium alginate (SA) as a depressant in the flotation process. The effect of SA on the flotation separation of bastnaesite and fluorite was evaluated using micro-flotation tests, zeta potential measurements, adsorption density measurements, Fourier infrared spectroscopy, and X-ray photoelectron spectroscopy. The micro-flotation results showed that SA exerted a strongly detrimental effect on fluorite flotation, while slightly affecting bastnaesite flotation. The surface chemistry results revealed that the -COO- and HO- functional groups in SA coordinated with Ca2+ on the fluorite surface, which induced hydrophilicity and hindered adsorption in the subsequent octylhydroxamic acid as a collector. However, the interaction of SA with the bastnaesite surface was marginal and did not affect the anchoring of the collector on the surface of bastnaesite. Based on these results, the present study proposes a possible model for the interaction of SA on the surfaces of the two minerals, laying a foundation for the flotation separation of bastnaesite from fluorite with SA as an environmentally benign depressant.

Flotation Separation of Fluorite from Calcite using an Efficient Depressant Nitrilotriacetic Acid in the NaOL System.

Fluorite and calcite were separated with nitrilotriacetic acid (NTA) as a depressant. The single mineral flotation experiment confirmed that with 40 mg/L NaOL and 80 mg/L NTA, the fluorite recovery and calcite recovery were 24.37 and 94.13%, respectively, at pH 9. Meanwhile, in the fluorite-calcite binary mixed ore flotation experiment, the calcite recovery and fluorite recovery were 75.50 and 26.84%, respectively, and the CaCO3 and CaF2 grade in concentrate was 74.32 and 25.61%, respectively. The results confirmed that NTA could be used as a depressant to selectively inhibit fluorite flotation. The mechanism study illustrated that NTA was selectively reacted with fluorite by chemical interaction between O of NTA and Ca of fluorite. The adsorption of NTA on fluorite will impede the interaction between fluorite and NaOL. NTA could adsorb on fluorite in three ways, while the dominant two ways were the complex between double O of NTA and Ca of fluorite in a vertical model and the complex between double O of NTA and Ca of fluorite in a horizontal model.

An integrated experimental and computational investigation of N,9,10-trihydroxyoctadecanamide as a potential collector for the flotation separation of fluorite and calcite

Hydrofluoric acid production heavily depends on fluorite (CaF2), a mineral frequently occurring alongside other calcium-rich minerals such as calcite (CaCO3). To separate fluorite from calcite and other associated minerals, flotation is the primary method employed. Oleic acid serves as the most commonly used collector in fluorite flotation. However, oleic acid exhibits poor selectivity and limited solubility at low temperatures. A novel fluorite flotation collector, N,9,10-trihydroxyoctadecanamide (THODA), is developed through the modification of the polar functional group of oleic acid, carboxyl, to an N-hydroxy amide group. Additionally, two hydroxy groups are introduced at the double bond position of oleic acid. Flotation experiments demonstrate that employing THODA as a collector can yield a fluorite recovery of approximately 90%, while the recovery rate of calcite ranges between 10% and 20%. THODA exhibits a superior selectivity in the flotation separation of fluorite and calcite compared to oleic acid. Zeta potential experiments reveal that following the treatment with oleic acid, the zeta potential of calcite surface rapidly decreases, whereas after the treatment with THODA, the zeta potential of calcite surface decreases to a lesser extent. This suggests that, under identical dosage conditions, THODA adsorbs less onto calcite surface compared to oleic acid. Consequently, THODA exhibits a weaker ability to collect calcite in comparison to oleic acid, thereby resulting in its enhanced selectivity over oleic acid.

Flotation separation of scheelite from fluorite by new depressant nitrilotriacetic acid and its mechanism

BackgroundFluorite and scheelite are main resources for fluorine and tungsten respectively, which are usually associated with each other, and the separation of them has important strategic meaning. For the first time, scheelite and fluorite were separated by using nitrilotriacetic acid (NTA) as depressant. MethodsThe effects of NTA on the flotation of scheelite and fluorite were investigated by flotation experiments. The selective adsorption mechanism of NTA on fluorite were revealed by atomic force microscope (AFM), zeta potential measurements, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Significant findingsNTA could achieve the efficient separation of scheelite from fluorite. Under the optimal separation conditions, the recovery of scheelite concentrate is 73.59 % and the grade of CaWO4 is 73.19 %, and the recovery and CaF2 grade of fluorite in tailings was 74.71 % and 79.44 % respectively. Mechanism study showed that although NTA had carboxy groups, NTA could not be adsorbed on scheelite surface due to the electrostatic repulsion and steric effect. However, NTA was strongly chemisorbed by calcium on fluorite, covering calcium groups and hiding the further adsorption of NaOL. Thus, NTA selectively disturbed NaOL adsorption and decreased the floatability of fluorite and realized the scheelite-fluorite separation.

Effect of sulfuric acid pretreatment on flotation performance of calcite and fluorite

Difficulty in separating calcite and fluorite owing to their similar surface properties is the focus of research in the field of mineral processing. To increase the selectivity difference between these two minerals, sulfuric acid was introduced as a surface pretreatmentand, and aluminium sulfate was used as the flotation depressant. The effects of H2SO4 pretreatment on calcite and fluorite flotation performance and the mechanisms thereof were studied by combining microflotation experiments, solution chemical calculations, scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS), Fourier transform infrared (FT-IR) spectroscopy, and density functional theory (DFT). Microflotation experiments showed that sulfuric acid pretreatment significantly reduced the flotation recovery of calcite to less than 10%, while it had little effect on fluorite, where the recovery reached greater than 80%. SEM-EDS and FT-IR analyses showed that, after sulfuric acid treatment, the surface composition of calcite was converted from CaCO3 to CaSO4, while the fluorite surface remained almost unchanged. DFT calculations showed that CaSO4 was more hydrophilic than CaCO3; therefore, it was more likely to interact with water molecules. The presence of water molecules affected the adsorption of the sodium oleate (NaOL) collector on the mineral surface. Therefore, the calcite surface adsorption ability of NaOL after sulfuric acid pretreatment was weakened, resulting in a significant decrease in flotation recovery.

The exploration of tannin extract as a green depressant in the flotation separation of fluorite from calcite

In response to the flotation separation issue of fluorite and calcite, the utilization of tannin extract (TE) as a depressant for the feasibility of two minerals separation was studied in this study. Microflotation results revealed that the high floatability of fluorite and calcite was obtained using the sodium oleate (NaOl) as the collector, and the addition of TE could completely depress the calcite flotation while it had small effects on the fluorite flotation. The flotation of artificial mixed fluorite/calcite confirmed that TE had the efficient and selective depressing ability to achieve effective separation performance. The adsorption measurements showed that the adsorption amount of TE on the calcite surface was much higher than that on the fluorite surface. Zeta potential results indicated that NaOl could be adsorbed on the fluorite surface but not on the calcite surface in the presence of TE. X-ray photoelectron spectroscopy illustrated that TE only chemisorbed onto the calcite surface but weakly interact with the fluorite surface. The computational chemistry analysis revealed that the adsorption energy of TE onto the calcite surface was much lower than that onto the fluorite surface. A stable four-member chelating compound was only generated by the chemical interaction between TE and calcite. Thus, TE can act as the potential depressant in the flotation separation of fluorite from calcite.

A novel surfactant N-hydroxy-9,10-epoxy group-octadecanamide. Part Ⅰ. Application in the flotation separation of fluorite/calcite and adsorption selectivity on the mineral surfaces

Oleic acid plays a crucial role as the primary collector in fluorite flotation. N-hydroxy-9,10-epoxy group-octadecanamide (N-OH-9,10-O-ODA) is synthesized by modifying the structure of oleic acid. This modification involves converting the carboxyl group, the polar functional group of oleic acid, into an N-hydroxy amide group and introducing an epoxy group. These modifications are aimed at enhancing the selectivity and collecting ability of oleic acid. Utilizing N-OH-9,10-O-ODA as the collector results in a significantly higher recovery rate of fluorite of approximately 95% compared to only about 20% for calcite. Fluorite surface treated with N-OH-9,10-O-ODA exhibits a more substantial negative shift in its zeta potential, approximately 73 mV, compared to N-OH-9,10-O-ODA-treated calcite surface, which only displays an absolute value of approximately 41 mV. The greater discrepancy suggests a greater adsorption quantity of N-OH-9,10-O-ODA on fluorite surface, thereby enhancing its ability to collect fluorite particles more effectively. First-principles calculations reveal a higher adsorption energy of N-OH-9,10-O-ODA on fluorite surface compared to calcite. The disparity indicates a greater adsorption intensity of N-OH-9,10-O-ODA on fluorite surface, resulting in its higher adsorption amount on fluorite surface.

Selectively separating scheelite from fluorite by using Nitrilotri(methylphosphonic acid) as an efficiency depressant to modify the surface properties of fluorite

Owing to the similar surface properties of scheelite and fluorite, the separation of them is very difficult by only using the traditional collectors of fatty acids. In this study, Nitrilotri(methylphosphonic acid) (ATMP) was used as a depressant to realize the efficient separation of these two minerals. The separation performance and the adsorption mechanism of ATMP on scheelite and fluorite were explored by the flotation experiments and surface analyses. Flotation results indicated that ATMP exhibited strong inhibition on the fluorite flotation but did not affect that of scheelite, and a satisfactory separation of scheelite from fluorite was achieved at the reagent regime of 60 mg/L ATMP, 40 mg/L sodium oleate (NaOL) and pH 10.0. Zeta potential measurements and AFM detections showed that the intense adsorption of ATMP onto fluorite was occurred and which could prevent the subsequent adsorption of NaOL on fluorite, while the adsorption of ATMP onto scheelite was weak and the further interaction between NaOL and scheelite was hardly influenced by it. Moreover, Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses confirmed that the interaction between calcium ions exposed on fluorite surface and the phosphate groups of ATMP accounted for the chemisorption of ATMP on fluorite. As a result, ATMP can be selected as a potential depressant for separating scheelite from fluorite.

Selective adsorption mechanism of SHMP onto fine fluorite in bastnaesite flotation system

The agglomeration of bastnaesite and fine fluorite severely reduces the recovery of bastnaesite, and a method to address this issue is urgently needed. Using measurement techniques such as micro-flotation, contact angle, zeta potential, in situ attenuated total reflectance-Fourier transform infrared (In situ ATR-FTIR) spectroscopy, and extended theory for calculating the stability of solution colloid (E-DLVO theory), this study investigated the selective adsorption mechanism of sodium hexametaphosphate (SHMP). The flotation results indicated that when sodium oleate (NaOL) was used as the collector, SHMP was 2.5 × 10−6 M, showing an outstanding flotation separation of bastnaesite from fine fluorite. The contact angle and zeta potential results showed that SHMP selectively increased the surface hydrophobicity and decreased the surface potential of fluorite. Additionally, in situ ATR-FTIR spectroscopy measurements revealed that HPO42- and H2PO4- of SHMP chemically reacted with Ca2+ ions on the surface of fluorite and finally formed CaHPO4 and Ca(H2PO4)2 stable complexes. However, SHMP was adsorbed by bastnaesite. Furthermore, EDLVO theoretical calculations confirmed that with the addition of SHMP, the electrostatic attraction of the double electric layer between the particles weakened 10 times, hydration repulsion was intense, and the total force between the particles changed from attractive to repulsive. The results also showed that fluorite and bastnaesite dispersed each other. Thus, SHMP can be used as a high-performance selective depressant for the fluorite flotation to realize bastnaesite flotation.

Selective Separation of Fluorite from Calcite Using Saponified Tridecanoic Acid as a Novel Collector

ABSTRACT Fluorite, as a vital calcium-containing mineral, usually coexists with calcite. When using the traditional collector sodium oleate (NaOL), froth flotation could not separate fluorite and calcite well on account of their similar surface properties. Meanwhile, a large amount of sodium silicate (SS) needs to be added to depress calcite, resulting in difficulties in tailings settlement and wastewater treatment. Therefore, a nontoxic and inexpensive surfactant saponified tricarboxylic acid (TA) was developed as a new collector. The flotation test results showed that TA had a higher selectivity for fluorite than NaOL, leading to the selective separation of both minerals. Zeta potential measurements indicated that TA was negatively charged and was strongly adsorbed on fluorite due to electrostatic interactions at pH 9.0. FTIR, XPS, DFT, and crystal chemistry calculations revealed TA had a stronger chemical interaction with fluorite due to its higher surface Ca activity and density, forming a TA-Ca complex through the bidentate coordination. In contrast, the interaction of TA with calcite could be ignored. In addition, the results of the surface tension and dynamic foam stability tests revealed that TA possessed the excellent foam performance. Therefore, these properties give TA excessive potential for industrial application and environmental protection in fluorite flotation.

Flotation separation of fluorite and calcite using anhydrous glucose and aluminum sulfate as a combined depressant

The effective flotation separation of fluorite and calcite is a critical problem in the mineral processing industry owing to their similar physicochemical characteristics. In this study, the effect of glucose (Glu) and Al3+ on the flotation separation of fluorite and calcite was studied using micro-flotation experiments, scanning electron microscopy (SEM), solution chemistry calculation, X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT). The micro-flotation experiments demonstrate that the combination of Glu and Al3+ had a significant depression effect on calcite. However, it slightly affected fluorite flotation. The SEM results indicate that Glu and Al3+ had a greater tendency of absorption on the calcite surface than that of fluorite. The solution chemistry calculation and XPS analysis exhibit that the increased selective depression of Glu on calcite with the addition of Al3+ was due to the formation of Al (OH) 3 and Al2O3 on the calcite surface. The DFT results exhibit that Ca-O bonds were formed when Glu interacted with fluorite. Additionally, Ca-O, C–H, and H-O bonds were formed when Glu interacted with the surface of calcite. The surface bonding characteristics of Glu with fluorite and calcite led to a difference in the adsorption energy. The glucose and Al2O3 glucose formed on the surface of calcite improved the adsorption through Al-O bond, which increased the adsorption sites on the surface of calcite and enhanced the depression effect of Glu on calcite.

Fluorite flotation separation from bastnaesite via an eco-friendly polymer as a depressant and insight into its mechanism of adsorption

Fluorite and bastnaesite are significant mineral resources, but they have comparable surface characteristics, making flotation separation challenging. An eco-friendly polymer depressant was used in this study, causticized cassava starch (CS), for flotation separation of fluorite and bastnaesite. Experimentation, molecular dynamics modeling, and characterization evaluation are used to identify the CS flotation adsorption process on minerals. These findings suggest that hydroxyl groups on CS branches can be weakly adsorbed on fluorite and bastnaesite surfaces by forming OH⋯F hydrogen bonds. CS belongs to causticized starch, which may adsorb on surfaces in a specific manner bastnaesite by developing the R′–CH2–O–Ce-R″ complex. Under the action of chemical adsorption and hydrogen bond adsorption, the adsorption energy of CS in bastnaesite is much larger than that in fluorite, which is −83.16 kJ/mol and −28.38 kJ/mol respectively. After a large amount of CS adsorption, the hydrophilicity of bastnaesite is awfully enhanced and the floatability is decreased. With intentionally mixed materials, flotation separation may provide a concentrate with 82.23 % CaF2 grading and 90.04 % CaF2 recovery. This study provides an idea for separating fluorite and rare earth by preferential flotation of fluorite and selective inhibition of bastnaesite.

Effect of Calcium Ion on the Flotation of Fluorite and Calcite Using Sodium Oleate as Collector and Tannic Acid as Depressant

In the flotation of semi-soluble minerals such as calcite and fluorite, Ca2+ is one of the common dissolved components influencing the collector adsorption behaviors on the mineral surfaces. However, there is very limited research focusing on how the dissolved Ca2+ affects the separation of fluorite and calcite. In the study, with sodium oleate (NaOL) as a collector and tannic acid (TA) as a depressant, a flotation test, zeta potential measurement, and adsorption experiment in the presence of Ca2+ were conducted. Flotation tests indicated that in the presence of Ca2+, fluorite and calcite were both significantly depressed by TA, leading to difficulty in the separation of the two minerals. It was also found that the depression effect on fluorite flotation was minimized with a high concentration of NaOL. Zeta potential measurement and the adsorption experiment results are consistent with the flotation results, revealing that it is only in the low concentration of NaOL that the flotation of fluorite was depressed by TA in the presence of Ca2+. Specifically, in the low concentration of NaOL, TA adsorbed on the fluorite surface and depressed the flotation of fluorite due to the preferential interaction between NaOL and Ca2+ in the solution leading to a shortage in the effective NaOL in the solution. In the high concentration of NaOL, the adsorbed TA on the fluorite surface was displaced by the excessive NaOL in the solution; hence, the flotation of fluorite was recovered. In contrast, TA always hinders the interaction of NaOL with calcite regardless of the presence and absence of Ca2+ and NaOL, hence, depressing the flotation of calcite. The study presented that a high concentration of NaOL may mitigate the negative effect of Ca2+ on the fluorite surface and improve the separation of fluorite from calcite.

Utilization of gellan gum as a novel eco-friendly depressant in the flotation separation of fluorite from barite

The relatively similar physicochemical features and floatabilities of fluorite and barite in the flotation process make the separation of these two minerals rather difficult. Exploration and utilization of efficient depressants is vital to improve the flotation separation performance. In this study, gellan gum (GG) was adopted as the depressant in the flotation separation of fluorite and barite with sodium oleate (NaOL) as collector for the first time. The inhibitory impact of gellan gum on the flotation performances of these two minerals was evaluated via flotation tests. The potential inhibiting mechanism of GG was systematically revealed via series of surface analytical measurements. Flotation experiments indicated that GG exhibited strong depressing effect on the barite flotation, whilst it showed little impact on the fluorite flotation. Zeta potential tests and surface wettability analyses demonstrated that GG intensely adhered onto barite and strongly prevented the subsequent NaOL adsorption, while it barely affected the NaOL adsorption onto fluorite. Adsorption capacity measurements confirmed that much higher amount of GG adsorbed onto barite than fluorite. Fourier transform infrared (FTIR) spectroscopy analyses and X-ray photoelectron spectroscopy (XPS) results implied that the quite weak physisorption of GG on the fluorite surface occurred, whereas strong chemical adhesion of GG occurred between GG and barite, which resulted in completely disparate flotation behaviors of these two minerals. As a result, selectively depression of barite flotation and the flotation separation of fluorite from barite were achieved. Therefore, GG can be used as an efficient and eco-friendly depressant to realize the flotation separation of fluorite and barite.

New insights into the role of calcium dioleate in selectively separating fluorite from calcite during cleaning process

Research on fluorite and calcite cleaning process have been ignoring the effects of calcium dioleate in pulp on flotation. In this study, flotation tests showed that flotation separation of fluorite and calcite could be achieved by the cleaning process under acidic conditions. Solution chemistry equilibrium calculations revealed that large amounts of calcium dioleate formed, and this compound was the main component in the cleaning solutions of fluorite and calcite under acidic conditions. Desorption and adsorption tests, contact angle measurements and atomic force microscopy (AFM) revealed the mechanism of selective separation of fluorite and calcite during the cleaning process under acidic conditions. Flotation tests showed that under acidic conditions, calcite flotation was strongly inhibited but fluorite flotation was less affected. Desorption and adsorption measurements and mineral surface contact angle analysis revealed that under acidic conditions, the calcium dioleate on the surface of calcite rough concentrate was desorbed into the solution, whereas the calcium dioleate in the solution did not readily absorb on calcite surface. The calcium dioleate on the surface of fluorite rough concentrate was hardly desorbed, whereas the calcium dioleate in the solution continued to adsorb on the surface. AFM intuitively confirmed the desorption of calcium dioleate from calcite surface and the adsorption of this compound on fluorite surface under acidic conditions. The selective adsorption of calcium dioleate on fluorite rough concentrate is an important factor that promotes the selective separation of fluorite and calcite during the cleaning process.

The role of copper ion and soluble starch used as a combined depressant in the flotation separation of fluorite from calcite: New insights on the application of modified starch in mineral processing

• Cu 2+ and soluble starch (SS) together enhance fluorite/calcite flotation separation. • The mechanism was systematically studied from chemical and atomic perspectives. • Cu SS complex interacts strongly with calcite but only weakly with fluorite . • Metal-ion modified starches are flotation reagents with great potential. The flotation separation of fluorite and calcite poses a long-standing challenge in the mineral processing industry because of their similar physicochemical characteristics. In this study, the effects of Cu 2+ and soluble starch (SS) in the separation of fluorite from calcite by flotation, and the mechanisms behind these effects, were investigated using micro-flotation experiments, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), time of flight secondary ion mass spectrometry (ToF-SIMS) and density functional theory (DFT). The micro-flotation experiments show that the combination of Cu 2+ and SS exhibits a stronger selective depression effect on calcite than that produced by SS alone; in contrast, the effect on fluorite flotation is relatively small. The XPS, FT-IR and ToF-SIMS analyses show that Cu 2+ can react with SS to form a Cu SS complex, which has better selectivity, resulting in the difference in flotation performance between fluorite and calcite. DFT results show that the SS and the Cu-SS complex form different chemical bonds during their interactions with the mineral surfaces: Ca O bond and H F bonds are formed when SS interacts with the fluorite surface, and Ca O and hydrogen bonds are formed when SS interacts with the calcite surface. A Ca Cu bond is formed when the Cu SS complex interacts with the fluorite surface, but both Cu O and Ca Cu bonds are formed when the Cu SS complex interacts with the calcite surface. This causes differences in adsorption energy. The adsorption energies of the interactions between SS or Cu SS complex and the surfaces of fluorite and calcite are ranked as: calcite + Cu SS complex > calcite + SS > fluorite + SS > fluorite + Cu SS complex.

Combined inhibitors of Fe3+, Cu2+ or Al3+ and sodium silicate on the flotation of fluorite and quartz

Fluorite ore, as an essential raw material in the fluorinated chemical industry, required effective separation and purification. The removal of impurities such as quartz becomes the key point in fluorite flotation. In this work, the fluorite flotation tests via adding the different mass ratios of metal ions (Fe3+, Cu2+, Al3+) and sodium silicate (SS) as a combined inhibitor, were carried out on a laboratory scale. Results indicated that when the mass ratio of SS to Fe3+, Cu2+, and Al3+ was 3:1, 1:1, and 3:1, the fluorite recovery reached 75.01%, 83.56%, and 81.84%, while quartz recovery was only 9.20%, 6.09%, and 4.76%, respectively. In addition, the action mechanisms of the combined inhibitors were investigated and evaluated in-depth. Compared with the single inhibitor of SS, the results of contact angle measurements, Zeta potential measurement, and Fourier transform infrared spectroscopy showed that the combined inhibitor could attenuate the activation of Ca2+ on quartz, and therefore to avoid the quartz mismatching into fluorite concentrates. Therefore, it provides an alternative separation method to realize high-efficient flotation of the fluorite and quartz with the presence of metal ion inhibitors.